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NAN048A: Nanotechnology in Coatings and Adhesive Applications: Global Markets

TABLE OF CONTENTS TABLE OF CONTENTS ............................................................................................... I LIST OF TABLES ................................................................................................... VIII INTRODUCTION ......................................................................................................... 1 STUDY GOALS AND OBJECTIVES ................................................................ 1 REASONS FOR DOING THIS STUDY ............................................................ 2 SCOPE AND FORMAT ..................................................................................... 2 METHODOLOGY .............................................................................................. 2 INFORMATION SOURCES .............................................................................. 3 RELATED BCC WORK CREDENTIALS ......................................................... 3 DISCLAIMER .................................................................................................... 4 BCC ON-LINE SERVICES................................................................................ 5 NANOTECHNOLOGY: BRIEF HISTORY, CURRENT STATUS, AND FUTURE PROJECTIONS............................................................................ 6 NANOCOATINGS AND NANOADHESIVES: BRIEF HISTORY, CURRENT STATUS, AND FUTURE PROJECTIONS ............................... 7 TABLE 1 ................................................................................................................... 8 GLOBAL MARKET FOR NANOCOATINGS .......................................................... 8 AND NANOADHESIVES THROUGH 2015 ($ MILLIONS) ................................. 8 Challenges for the Implementation of Nanocoatings .................. 8 Brief History of Coatings .............................................................. 9 TABLE 2 ................................................................................................................. 10 OVERALL GLOBAL MARKET FOR COATINGS ................................................ 10 AND ADHESIVES THROUGH 2015 ($ MILLIONS) .......................................... 10 TABLE 3 ................................................................................................................. 10 MARKET SECTORS FOR CONVENTIONAL ..................................................... 10 COATINGS AND ADHESIVES (2009) ($ MILLIONS) ........................................ 10 TABLE 4 ................................................................................................................. 11 OVERVIEW OF GLOBAL COATINGS MARKET ................................................ 11 TOP COMPANIES WITH EARNINGS OVER $100M (2009) .............................. 11 NANOCOATINGS ...................................................................................................... 15 TABLE 5 ................................................................................................................. 16 GLOBAL NANOCOATINGS MARKET ................................................................ 16 BY REGION THROUGH 2015 ($ MILLIONS) .................................................... 16 TABLE 6 ................................................................................................................. 16 GLOBAL NANOCOATINGS MARKET ................................................................ 16 BY SECTOR THROUGH 2015 ($ MILLIONS) .................................................... 16 NANOCOATINGS IN MEDICAL APPLICATIONS ....................................... 17 Nanoparticle Coatings in Medicine ............................................ 17 TABLE 7 GLOBAL NANOCOATINGS MARKET IN THE ............................... 18 Copyright© BCC Research, Wellesley, MA USA, Web: www.bccresearch.com/

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HEALTH CARE SECTOR THROUGH 2015 ($ MILLIONS) .............................. 18 Silica Nanocoatings for Core-Shell Nanoparticles ..................... 18 Nanocoatings for Quantum Dots ................................................ 19 Alkanethiol Self Assembled Monolayers (SAMs)....................... 20 Nanocoating Methods for SAMs ................................................. 21 Crystal Seeding with SAMs ....................................................... 22 Biosurfaces Enabled with SAMs ................................................ 22 SAMs-Based Biosensors ............................................................. 23 BIOMEDICAL IMPLANTS .................................................................. 23 TABLE 8 GLOBAL NANOCOATINGS MARKET FOR MEDICAL/DENTAL ........................................................................................ 24 IMPLANTS AND ARTIFICIAL JOINTS THROUGH 2015 ($ MILLIONS) ....... 24 Nanostructured Diamond Coatings for Biomedical Implants ................................................................................ 25 Implanted Orthopedic Monitoring Devices ................................ 26 Nanostructured Metalloceramic Coatings ................................. 26 Dental Implant Nanocoatings .................................................... 27 Biocompatible and Corrosion Resistant Diamond Coated Implants ................................................................................ 27 Hydroxyapatite Nanocoatings .................................................... 28 Polyelectrolyte Multilayer Orthopedic Nanocoatings ................ 29 Synthetic Diamond Nanocoatings .............................................. 29 TABLE 9 ................................................................................................................. 30 CVD DIAMOND FILM PROPERTIES.................................................................. 30 Carbon Nanotube Coatings ........................................................ 32 Infection Resistant Ventricular Assist Driveline....................... 33 On-Q-SilverSoaker Catheter Coating ........................................ 34 PLASM/PLASF Biomedical Device Coatings ............................. 35 NanoCOAT, NanoFUSE and NanoDOX .................................... 35 Antibacterial Surface Nanocoatings .......................................... 36 Bioactive Implant Nanocoatings ................................................ 37 Nanoemulsive Burn Treatment ................................................. 37 Nanomatrix Stent Coating ......................................................... 37 Polyzene-F Nanocoated Cardiac Stents ..................................... 38 Biliary Stent Clogging Solved by Nanotechnology .................... 38 Antimicrobial Barrier Dressings ................................................ 39 Nanofilms for Scar Free Surgery ............................................... 40 Nanocoatings for Hearing Aids .................................................. 40 Nanocoating for Cochlear Implant ............................................. 41 Nanocoating for Dermal Patch ................................................... 41 Analyte Biosensor for Detection of Drug Abuse ........................ 42 Carbon Nanotube Coatings for Bone Tissue Engineering ......... 42 FILMskin Project ........................................................................ 43 Cubosome Artificial Vernix ........................................................ 43

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Titania Nanotube Drug-Eluting Coatings ................................. 43 Carbon Nanotube Coated Brain Probe Electrodes .................... 44 Nanobiomaterial Coating for Brain Implant Electrodes ........... 45 Nanocoating for Surgical Blades ................................................ 46 Nanocoated Ibuprofen Tablets ................................................... 47 NANOCOATING SYNTHESIS TECHNIQUES................................... 47 Chemical Vapor Deposition (CVD) ............................................. 47 TABLE 10 ............................................................................................................... 48 TYPES OF CHEMICAL VAPOR DEPOSITION (CVD) ....................................... 48 Pulsed Laser Deposition ............................................................. 50 Layer by Layer Self-Assembly.................................................... 50 Langmuir-Blodgett Nanoarchitectures ...................................... 51 Ultrasonic Nanocoating .............................................................. 52 Glancing Angle Deposition (GLAD) ........................................... 52 TABLE 11 ............................................................................................................... 53 TYPES OF CONVENTIONAL INDUSTRIAL COATINGS ................................. 53 TABLE 12 EXEMPLAR TYPES OF NANOCOMPOSITE................................... 54 COATINGS AND ADHESIVES............................................................................. 54 TABLE 13 ............................................................................................................... 54 NANOCOATING ADDITIVES .............................................................................. 54 CHARACTERIZATION OF NANOCOATINGS ................................... 56 X-ray Diffraction ......................................................................... 56 Scanning Probe Microscopy ........................................................ 56 Scanning Tunneling Microscope (STM) ..................................... 57 Atomic Force Microscope (AFM) ................................................ 57 Raman Spectroscopy ................................................................... 58 NANOCOATINGS IN THE CONSTRUCTION SECTOR ................... 59 Antimicrobial Wall Paint............................................................ 59 Silver Nanoparticle Surface Coating.......................................... 59 Diamon-Fusion for Silica-Based Surfaces .................................. 60 Fire Protective Nanocoatings ..................................................... 60 Anti-Graffiti Nanocoating .......................................................... 61 Ceramic Thin Film Electrochromic Windows ............................ 61 Nansulate Nanocoatings ............................................................ 61 TABLE 14 GLOBAL NANOCOATINGS MARKET IN THE ............................. 63 CONSTRUCTION SECTOR THROUGH 2015 ($ MILLIONS) .......................... 63 NANOCOATINGS IN THE TEXTILE SECTOR.................................. 64 Nanocoatings in Textile Finishing ............................................. 64 Self-Assembled Nanolayers on Textile Fibers ........................... 65 Nanosilver Textile Finishing ...................................................... 66 Zinc Oxide Nanoparticle Textile Finishing ................................ 66 Dyeable Polypropylene Fibers .................................................... 67 Magnetite Nanoparticle Coated Paper....................................... 67 Sewing Needle Nanocoating ....................................................... 68


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Nanocoatings for Yarn Dyehouse Machinery ............................ 68 TABLE 15 GLOBAL NANOCOATINGS MARKET IN THE ............................. 69 TEXTILE SECTOR THROUGH 2015 ($ MILLIONS) ........................................ 69 NANOCOATINGS IN THE MILITARY AND SECURITY SECTORS ......................................................................................... 69 Glass Nanocoating for US Army Military Vehicles ................... 70 Nanocoatings for Aerospace Composite Tooling ........................ 70 Localized Interleukin-12 Delivery.............................................. 70 Chemical Decontaminating Nanocoating .................................. 71 Self-healing Nanocoating ........................................................... 71 Anti-Counterfeiting Nanocoating ............................................... 72 TABLE 16 GLOBAL NANOCOATINGS MARKET IN THE ............................. 72 MILTARY AND SECURITY SECTORS THROUGH 2015 ($ MILLIONS) ........ 72 NANOCOATINGS IN THE ENERGY SECTOR .................................. 73 Silicon Ink for Solar Cells ........................................................... 73 Anti-Reflective Nanocoatings ..................................................... 74 Nanocoating for High Temperature Tolerant Electronics ......... 75 Advanced Catalytic Coatings in Olefin Production ................... 76 Oil Lubricant Additive ................................................................ 76 Oil and Gas Drill Pipe Corrosion Control .................................. 77 Biofuel Cell Nanocoating ............................................................ 77 TABLE 17 GLOBAL NANOCOATINGS MARKET IN THE ENERGY SECTOR THROUGH 2015 ($ MILLIONS) .................................................... 78 NANOCOATINGS IN THE ELECTRONICS SECTOR ....................... 79 Barium Strontium Titanate Nanocoatings for DRAM Devices ................................................................................... 79 Microcantilever Biosensor Nanocoatings ................................... 79 Multi-Layered Nanocoatings for Optical Applications .............. 80 Antimicrobial Nanocoating for Computer Accessories .............. 81 Liquid Nanotechnology ............................................................... 81 Anti-Radiation Nanocoatings ..................................................... 82 Shielding for Electromagnetic Interference Gaskets ................. 82 Switchable Radio Frequency Shield ........................................... 82 Grown in Place Carbon Nanotube and Nanowire Electronics ............................................................................. 83 Protein Coated Nanostructured Surfaces for Nanociruitry....... 83 Nanostructured Zeolite-Based Coatings .................................... 85 TABLE 18 GLOBAL NANOCOATINGS MARKET IN THE ............................ 86 ELECTRONICS SECTOR THROUGH 2015 ($ MILLIONS) .............................. 86 NANOCOATINGS IN THE TRANSPORTATION SECTOR ............... 87 Anti-Fogging Nanocoating.......................................................... 87 Zyvere Multi-Application Nanocoating ...................................... 88 Ultralow-Friction Diamond-Like Carbon................................... 88 Anti-Corrosion Nanodiamond Coating ....................................... 89


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NanoLub Solid Lubricant ........................................................... 89 Anti-Fouling Nanocoatings ........................................................ 90 Anti-Icing Nanocoating .............................................................. 91 Scratch Resistant Nanoparticle Paint ....................................... 91 Erosion-Resistant Nanocoatings for Gas Turbine Engines ....... 92 Zeolite-Based Hydrophilic Nanocoating..................................... 92 Zeolite-Based Anti-Corrosion Nanocoatings .............................. 92 TABLE 19 GLOBAL NANOCOATINGS MARKET IN THE ............................. 93 TRANSPORTATION SECTOR THROUGH 2015 ($ MILLIONS) ...................... 93 TABLE 20 MARKET SEGMENTS FOR NANOCOATINGS IN THE ............... 94 TRANSPORATION SECTOR THROUGH 2015 ($ MILLIONS) ........................ 94 NANOCOATINGS IN THE FOOD SECTOR ....................................... 95 Edible Inorganic Nanocoatings .................................................. 96 Nanocoatings in Food Packaging ............................................... 97 Nanocomposite polymers ............................................................ 97 Embedded or Printed Nanosensors for Food Packaging ........... 98 Salmonella Bacteria Detection ................................................... 98 Multiple Pathogen Detection...................................................... 99 BioMark Pathogen Detection Spray........................................... 99 Electric Tongue ........................................................................... 99 Biogenic Amine Detection ........................................................ 100 Nanoscale Printed Bar Code Systems ...................................... 100 Ripesense Ripeness Indicator Label ........................................ 100 NanoBioswitch ”Release on Command” Preservatives ............ 101 Nanolok High Barrier Nanocomposite Coating ....................... 101 Silver Nanocoated Refrigerators .............................................. 102 Polymer Opal Films .................................................................. 102 Color Changing Indicators ....................................................... 103 Antimicrobial Food Packaging ................................................. 103 TABLE 21 GLOBAL NANOCOATINGS MARKET IN FOOD ........................ 104 AND BEVERAGE SECTORS THROUGH 2015 ($ MILLIONS) ....................... 104 NANOCOATINGS IN THE COMMERCIAL SECTOR ...................... 105 NanoNuno Umbrella ................................................................ 105 ÆGIS Microbial Shield ............................................................. 105 Anti-Friction Nanocoating for Pump Vanes and Tools ............ 106 Hydrophobic Coated Sand ........................................................ 106 Optical Nanocoating for Fishing Tackle .................................. 107 Nanocoated Guitar Strings....................................................... 107 Nanocoated Sports Balls .......................................................... 107 TABLE 22 GLOBAL NANOCOATINGS MARKET IN THE .......................... 108 COMMERICIAL SECTOR THROUGH 2015 ($ MILLIONS) ........................... 108 SAMPLE OF NANOCOATINGS AND NANOADHESIVES .................................. 109 COMPANY PROFILES ............................................................................................ 109 Copyright© BCC Research, Wellesley, MA USA, Web: www.bccresearch.com/

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ACRYMED, INC. 9560 SW Nimbus Avenue Beaverton, Oregon, USA ........................................................................ 109 97008 Phone: (503) 624-9830 Fax: (503) 639-0846 Email: [email protected] ......................................................... 109 ACULON, INC. .............................................................................................. 109 ADVANCED COATING ................................................................................ 110 ADVANCED DIAMOND TECHNOLOGIES, INC. ...................................... 111 ADVANCED NANO COATINGS, INC. ........................................................ 112 AEONCLAD COATINGS .............................................................................. 113 AFE TECHNOLOGY COATINGS, LTD. ...................................................... 113 AMBIT CORPORATION ............................................................................... 114 APPLIED THIN FILMS, INC. ...................................................................... 115 CG2 NANOCOATINGS, INC. ....................................................................... 116 CHAMELIC, LTD. ......................................................................................... 117 CLEANCORP NANOCOATINGS ................................................................. 117 COATING SYSTEMS LABORATORIES INC. ............................................. 118 CONCENTRIS GMBH................................................................................... 119 COTEC GMBH .............................................................................................. 120 DERN LIN TEXTILE CO., LTD. ................................................................... 120 DFI- DIAMON-FUSION INTERNATIONAL, INC. ..................................... 121 DURASEAL PIPE COATING COMPANY .................................................... 122 ECOLOGY COATINGS, INC. ....................................................................... 123 ECOSYNTHETIX .......................................................................................... 124 EVINCE TECHNOLOGY .............................................................................. 124 EVONIK INDUSTRIES AG .......................................................................... 125 HARMAN TECHNOLOGY, LTD. ................................................................. 126 INDUSTRIAL NANOTECH, INC. ................................................................ 127 INFRAMAT CORPORATION ....................................................................... 128 INNOVALIGHT, INC., .................................................................................. 128 LAAMSCIENCE, INC. .................................................................................. 129 NANO CHEM TECH INC. ............................................................................ 130 NANOCOATINGS PTY, LTD........................................................................ 131 NANO-TEX .................................................................................................... 132 NANOTHERAPEUTICS, INC. ...................................................................... 132 NANOVATIONS PTY, LTD. ......................................................................... 134 NANOVERE TECHNOLOGIES, INC. .......................................................... 135 NATURALNANO, INC. ................................................................................. 136 NCOAT ........................................................................................................... 136 NERITES ....................................................................................................... 137 P2I, LTD......................................................................................................... 138 SPIRE BIOMEDICAL ................................................................................... 139 SUB-ONE TECHNOLOGY, INC. .................................................................. 140 TOPCHIM ...................................................................................................... 140 ZYVEX PERFORMANCE MATERIALS ....................................................... 141


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NANOADHESIVES.................................................................................................. 143 TABLE 23 ............................................................................................................. 144 GLOBAL NANOADHESIVES MARKET ............................................................ 144 BY REGION THROUGH 2015 ($ MILLIONS) ................................................... 144 TABLE 24 GLOBAL NANOADHESIVES MARKET BY SECTOR ................. 144 THROUGH 2015 ($ MILLIONS) ......................................................................... 144 A BRIEF HISTORY OF ADHESIVES ................................................ 145 TABLE 25 ............................................................................................................. 145 SURVEY OF CONVENTIONAL ADHESIVES................................................... 145 TABLE 26 POLYMERS USED IN TRADITIONAL ADHESIVES................... 146 TABLE 27 ............................................................................................................. 147 TYPES OF NANOADHESIVES .......................................................................... 147 BIOMIMETIC NANOADHESIVES .............................................................. 148 DRY NANOADHESION ..................................................................... 148 Gecko Inspired Carbon Nanotube Arrays ................................ 148 Directional Adhesion Carbon Nanotube Arrays ...................... 149 Janus-Faced Nanopillars.......................................................... 150 Biomimetic Mushroom Fibrillar Adhesive ............................... 150 WET NANOADHESION ..................................................................... 151 Biomimetic Mussel Adhesion ................................................... 151 Reversible “Geckel” Nanoadhesive ........................................... 152 Super Adhesion of Bacterial Cells ............................................ 153 MEDICAL NANOADHESIVES .......................................................... 154 Duraseal Spine Sealant System ............................................... 154 Nano-Velcro Bio-bandage ......................................................... 154 Dental Poss Nanoadhesive ....................................................... 155 Nano-Adhesive Plaster ............................................................. 155 TABLE 28 GLOBAL NANOADHESIVES MARKET IN THE .......................... 156 HEALTH CARE SECTOR THROUGH 2015 ($ MILLIONS) ............................ 156 NANOADHESIVES IN ELECTRONICS ........................................... 157 Electrically Conductive Adhesive for Microelectronics ........... 157 Nanomaterials Enhancement of Epoxy Adhesives .................. 157 Biomimetic Nacre using Marine Bioadhesive .......................... 157 Nano-Alumina Modified Epoxy-Based Adhesives ................... 158 Nano-Imprint Resists for Adhesive Wafer Bonding ................ 159 ADDITIONAL TYPES OF NANOADHESIVES ................................. 159 Nanoadhesive for Pressure Sensitive Labels ........................... 159 Magnetically Activated Iron Oxide and Silicon Dioxide .......... 160 Epovex Adhesive for Aerospace ................................................ 160 Aluminum Oxide Nanoparticle Enhanced Epoxy .................... 161 Nanocomposite Pressure Sensitive Adhesives ......................... 161 DNA “Glue” for Nanostructure Assembly ................................ 162 High Temperature Organosilane Nanoadhesive ..................... 162 TABLE 29 ............................................................................................................. 163


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SURVEY OF GLOBAL NANOADHESIVE RESEARCH ................................... 163 (2009) .................................................................................................................... 163 TABLE 30 ............................................................................................................. 164 NANOADHESIVE ADDITIVES .......................................................................... 164 PATENT SURVEY AND ANALYSIS ...................................................................... 166 TABLE 31 ............................................................................................................. 167 SURVEY OF PATENTS AND PATENT APPLICATIONS FOR NANOCOATINGS AND NANOADHESIVES FROM 1976 TO 2009 ........... 167 CONCLUSION............................................................................................... 169

LIST OF TABLES


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INTRODUCTION STUDY GOALS AND OBJECTIVES This report will focus on the application of nanotechnologies in the coating and adhesive industries and will quantify their current and projected global markets to 2015. These nanomaterials-based products are enabled by unique constituent nanoparticulate, nanocrystalline, or colloidal compositions, dimensions, geometries, molecular-scale electronic properties, as well as other inbuilt nanometric processes and kinetics. Combinations of these elements have strong potential for enabling significantly improved, or entirely new and novel capabilities. These competencies would have likely been deemed as unattainable in the recent past. The report will also touch on the roles that nanostructured surface features and their resulting properties may play when they work in conjunction with these coatings and adhesives. A myriad of important capabilities can be enabled by nanotechnology-based coatings and adhesives (for simplicity’s sake, henceforth, these will be referred to as nanocoatings and nanoadhesives). There will undoubtedly be a number of “crossapplication” nanocoating and nanoadhesive formulations, which when reconfigured will have the potential for diverse applications across several market sectors. For example, self-cleaning nanocoating products for the automotive industry are likely to be specifically formulated for this sector, and will exhibit properties that are different from the self-cleaning nanocoating products that are designed for construction/architectural applications. Antimicrobial nanocoating formulations utilized to keep hospital surfaces free from bacteria, will likely be much different that the antimicrobial nanocoating formulations used for in vivo catheters or stents. In addition, there are likely to be a number of nuances where nanocoatings or nanoadhesives may be valid in both categories. For example, certain nanocoatings that serve to functionalize the bare surfaces of given material; making it more receptive to further modification, may also function as an adhesive undercoat. A full range of distinctive nanocoatings and nanoadhesives that are currently on the market, as well as various “products in progress”, which show promise for beneficial future applications will be explored. A survey of relevant patents, companies that manufacture and market these products, and research groups that are engaged in the development of next generation nanocoatings and nanoadhesives will be conducted.


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REASONS FOR DOING THIS STUDY Robust potential markets for nanocoatings and nanoadhesive products exist worldwide for a myriad of applications spanning medical and health care, electronics, energy, transportation, construction, packaging, forestry, textile, and homeland security sectors to name a few. These innovative nanotechnologies have the capacity for enabling a wide range of “smart” functional surfaces and interfaces as well as the development of advanced, highly effective, yet economical bonding, and connection capabilities. This report will serve to elucidate the latest developments in these fascinating areas, survey a range of products that are already impacting specific market sectors, and explore how these particular innovative nanotechnologies will contribute to the reshaping of our world. SCOPE AND FORMAT This report will be divided into two primary sections (nanocoatings and nanoadhesives) to survey existing and emerging technologies in these markets worldwide; survey and provide an analysis on relevant patents, as well as to profile the key companies involved with the development of products in these areas. Current and projected global markets for these particular nanotechnologies will be elucidated and segmented into geographical regions and countries. (note: all revenue figures are in U.S. dollars) METHODOLOGY The methodology involved in the compilation of this report included extensive literature searches, and the assimilation and distillation of global scale nanocoatings and nanoadhesives related research. Where clarification or additional information was required to further elucidate specific technologies, individual researchers were contacted. Companies were consulted when a more in-depth description of their processes, products and perceived markets was warranted. The market values expressed within this report include those attributed to the dedicated research involved for specific items, as well as the valuation of finished products. Nanotechnology may be perceived as a fundamentally enabling and valueadding platform with the potential capacity for encompassing virtually every business/market sector. Therefore, when describing various facets of the nanocoatings and nanoadhesives applications market, the author feels that a distinction should not be made between the worth of particular products and/or processes, and those of the integrated nanomaterials explicitly, which serve to improve their quality and performance.


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The rationale here is that many products and processes that have been, or will be, enhanced and further functionalized via nanotechnology might be less, or not at all, likely to be considered for purchase were it not for their value-added “nanoness” factor. The markets for these goods themselves may be generated, to a significant degree, by virtue of the nanomaterials, nanoscale engineering, and/or nanodevices that they contain, and the added benefits that they convey. Hence, a blended value for these markets seems appropriate. INFORMATION SOURCES The majority of information sources used in this report were derived from online literature searches, journal-published scientific papers, editorials, news articles, and government as well as global databases, reports and briefings. Numerous books and magazines were consulted for relevant technological information, or for background sections. Information from researchers that are considered as experts in their respective fields, and from nanocoating and nanoadhesive producing companies was also consulted. RELATED BCC WORK CREDENTIALS The author has been involved with intensive research related to nanotechnology and nanomedicine since 1996. He has conceptualized and designed many nanomedical components, devices, and systems, and generated potential nanodevice deployment and retrieval strategies. Over the years he has managed to engage a number of international nanotechnology and nanomedicine researchers in collaborating on these projects. In 2008 he incorporated a startup company called NanoApps Medical, Inc. along with these researchers with the aim of developing innovative and advanced nanomedical diagnostic and therapeutic components, devices, and systems. The author has been involved with journal article and book chapter contributions as relates to various aspects of nanomedicine in regard to device concepts, designs, and envisaged nanodevice functionality. He has written a research report for the Center for Responsible Nanotechnology on the topic of DNA-based manufacturing, and is in the process of preparing a manuscript for a book on the topic of nanomedical component, device and systems design for CRC Press. Cumulative work to date has provided the author with a unique perspective and focused background with which to approach many aspects of nanotechnology. There are myriad, frequently overlapping, and complex pathways that nanotechnologies are most likely to follow toward their anticipated beneficial applications in many diverse areas. It is hoped that this report will assist in elucidating how


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nanotechnology applications in the coating and adhesive sectors may be of benefit to us all. DISCLAIMER This report provides informative material of a professional nature. It does not constitute managerial, legal, or accounting advice nor should it serve as a corporate, company, or investment policy guide, or an endorsement of any given product or company. The information is intended to be as accurate as possible at the time it was written. The author assumes no responsibility for any losses or damages that might result because of reliance on this material. Note: As with any new technology, especially for nanotechnology, which is widely anticipated to be fundamentally disruptive and enabling, it can be challenging to estimate quantitatively how new nano-enhanced products and processes will fare in the marketplace. Although a number of nanocoating and nanoadhesive technologies have been introduced to market, the commercialization timeline of others is less clear, as they are either still at the laboratory research or testing/trial stages. Others will remain queued for release pending further development to address issues such as cost effectiveness and high volume manufacturing, functional verification, appropriate packaging, and the mounting of a reasonable assurance of safety as relates to human health and the environment at large. Market estimates presented via the tables within this research report are derived from current and projected nanocoating and nanoadhesive markets and facets thereof. Perceived demand for these enhanced products is based on certain criteria such as their current levels of development and maturity, specific functionality, available quantity, and potential for overlap, (e.g., self-assembling monolayers might be used as both nanocoatings and nanoadhesives). Nanocoating and nanoadhesive technologies included in the tables below are shown to be either under development (UD) or in production (IP) for the particular application. All figures shown (especially for 2010 - 2015) include estimated research funding aimed at their development. All estimates will undoubtedly be subject to vagaries in demand and to the uncertainties inherent to the markets themselves, and therefore should be construed as relatively fluid.


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BCC ON-LINE SERVICES  Copyright 2009 by Business Communications Co. Inc. Norwalk CT 06855. Reproduction of any material in this report is strictly forbidden without express permission of the Publisher. To receive a complete catalog of BCC studies, please complete the order form at the back of this report or visit our Web site at www.bccresearch.com.


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NANOTECHNOLOGY: BRIEF HISTORY, CURRENT STATUS, AND FUTURE PROJECTIONS Nanotechnology is a nascent, vibrant, and burgeoning scientific discipline that is predicted to have important implications for an extraordinarily broad array of applications encompassing almost every market sector. It is surmised that virtually no facet of industry will be left uninfluenced by its seemingly ubiquitous reach. Nanotechnology is defined as the capacity for the controllable manipulation of matter at the molecular and atomic levels, typically from 1 nm to 100 nm. It allows for and encompasses the fundamental ability to synthesize novel materials and to create devices that exhibit extraordinary properties with enhanced functionality. One compelling driver of this technology lies in the premise that matter behaves in radically different ways for nanoscale materials in contrast their bulk material counterparts. Nanoscale materials can possess innumerable components that are endowed with exponentially greater surface areas, which are critical in many industrial processes such as chemical catalysis or when endeavoring to design biomimetic dry glues to emulate the remarkable adhesive kinetics of the gecko foot. Richard Feynman gave flight to the concept of nanotechnology via his 1959 introductory lecture “There’s Plenty of Room at the Bottom.” In 1987 K. Eric Drexler’s book Engines of Creation articulated the promise of this new science in diverse range of future scenarios. An important development that transitioned many “nanovisions” into tangible reality was the development of Scanning Tunneling microscopy (1981) and Atomic Force microscopy (1986). These instruments enabled imaging at nanometric resolution and the manipulation of individual atoms. Since then there has been a virtual explosion of nanotechnology research. In its 2008 Nanotechnology Opportunity Report, Cientifica Ltd estimated that the value of nanotechnology enabled products stood at $166.6 billion, while funding for nanotechnology worldwide amounted to $25 billion. In 2009, U.S. President Barack Obama sent a budget request to Congress calling for a sum of $1.5 billion for the National Nanotechnology Initiative (NNI). A 2010 budget of $1.64 billion is proposed for the NNI. The cumulative value of nano-enhanced products and processes is slated by some estimates to reach as high as $3 trillion by 2015, which represents about 15% of the worlds product output.


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NANOCOATINGS AND NANOADHESIVES: BRIEF HISTORY, CURRENT STATUS, AND FUTURE PROJECTIONS Many companies have begun to evaluate and implement nanocoatings and nanoadhesives into their product portfolios as they have demonstrated the capacity for imparting many attractive benefits for improved performance and added value for their customers. These nascent markets are just beginning to emerge, but have been constrained somewhat. According to the ChemQuest Group, the recent tenuous economy has initiated about a 10% drop in the conventional coatings and adhesives markets, which is likely to continue through 2009. However, the nanotechnology market has continued to develop, with estimates of global nanoenhanced products and services attaining $3 trillion by 2015, which translates to approximately 15% of the global output of goods. Table 1 gives an overview of the global market estimates for the nanocoating and nanoadhesive segments of this business. The decimated U.S. housing market, shaky automotive sector, beleaguered airline industry, an increase in the price for raw materials, and tighter environmental regulations have not factored positively to bolster the coatings and adhesives sector. This, along with a general sense of unease as the unemployment figures in the U.S. hover at ~9.5%, and in some metropolitan areas, as high as 15%. Though a slow recovery seems inevitable as the economy struggles to finds its feet, there appear to be glimmers on the horizon. There are a number of attractive criteria that the producers of nanocoatings and nanoadhesives are aiming to satisfy, which may serve as potent market drivers.

 Environmentally friendly/green, recyclable, helps to impact climate change.  Far less bulk material required and hence less processing time and energy           

expenditure. Enhanced functionality. Simple application, far less re-application. Low or no maintenance for extended time periods. New, novel and “Wow” factors. Improved efficiency, multi-functional/multi-application. Lower cost of production, storage, shipping, use, disposal. No toxic ingredients and replacement of existing toxic ingredients. Reduction in required production real estate in manufacturing facilities. Simple to diversify/tune functional properties. Smart/intelligent coatings, self healing, can be embedded with nanosensors. Energy harvesting/generating.


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 Need for increased use in defense and security to maintain lead in advanced technologies.  Reversible adhesion.  Wet adhesion, never before possible.  Greatly enhanced quick release dry adhesion. TABLE 1 GLOBAL MARKET FOR NANOCOATINGS AND NANOADHESIVES THROUGH 2015 ($ MILLIONS)

Category

2008

Nanocoatings 1,382.0 Nanoadhesives 81.6 Total 1,463.6 Source: BCC, Inc., Nanoposts

2009

2010

2015

2,139.5 171.4 2,310.9

3,395.0 257.0 3,652.0

17,956.0 1,213.3 19,169.3

CAGR% 2010-2015 39.5 36.4 39.3

Challenges for the Implementation of Nanocoatings Although there exists an ongoing flurry of exciting and promising research activity as relates to the functional modification of material surfaces, there remains a definite necessity for the development of straightforward and adaptable approaches to surface modification. There are a number of issues that will need to be resolved prior to the widespread practical implementation of nanocoatings. Some of these items include evolving the capacity for repeatably producing high caliber chemical specificity between interfacial modifiers and surfaces (e.g., alkanethiols on noble metal and silanes on oxides) at commercial scale fabrication volumes, a requirement for the use of complex instrumentation, current limits on substrate size and shape, and synthesis protocols requiring multi-step procedures. The estimation of global markets for nanocoatings and nanoadhesives is somewhat elusive as many of these nanotechnologies are still sequestered in laboratories, undergoing preliminary trials, or are just emerging into the marketplace. Hence in the tables that follow, nanocoating or nanoadhesive applications will be denoted as either under development (UD) or in production (IP).


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Brief History of Coatings

 350,000 - 400,000 BC – Evidence of pigment and paint grinding equipment in                  

Zambia. 28,000 BC – Earliest painting activity in caves of southern France using earth and natural pigments (ochre). 5000 BC – Lacquer originates in China derived from tree sap for protective coatings. 3000 BC - Varnishes and enamels made from beeswax, gelatin, and clay were in use, and then pitch and balsam for waterproofing wooden boats. 1200 BC – Lacquered coffin of Fu Hao - consort to Shang Dynasty Emperors. 1000 BC - Egyptians developed varnishes made from gum Arabic. 300 BC - Druids develop durable protective coatings using ox blood and lime. 200 BC - Independent development of lacquers and varnishes in China, Japan and Korea. 600-800 AD - Pre-Columbian use of Maya Blue pigment, made of indigo and palygorskite clay. Resists humidity, biodegradation, and damage by acids alkalis, and chemical solvents. 1700 – Earliest known paint mill in the U.S. using large round milling stones. 1837 - Sorel (Paris, France) patents a process for coating iron by dipping into molten zinc (galvanizing). 1850 – First lacquer for inside surfaces of cans (France). 1867 – First generation of ready mix paints for residences. 1869 – British patent issued for corrosion protection treatment for iron by dipping hot iron into phosphoric acid. 1906 - British patent issued for iron and steel treatment by immersion in phosphoric acid and iron filings. 1923 – Development of first known test method for harness of paints using pencils. 1926 – Metal anodized coatings. 1935 – First protective coating for commercial beer cans. 1941 - Pearson Survey technique for the detection of coating defects on buried pipelines. An AC signal is propagated onto the pipeline and compared with the potential gradient along the pipeline spanning two mobile earth contacts.

Table 2 provides an overview of the global coatings and adhesives markets, whereas Table 3 categorizes the primary market sectors involved. The main corporate entities involved in the traditional coatings market are depicted in Table 4. These corporations may likely play a significant role toward the introduction and eventual widespread acceptance of nanocoatings and nanoadhesives, as they undoubtedly are


9


or soon will be fully cognizant of the potential value of these new and rapidly growing markets. TABLE 2 OVERALL GLOBAL MARKET FOR COATINGS AND ADHESIVES THROUGH 2015 ($ MILLIONS) Category

2008

Coatings 92,144 Adhesives 40,777 Total 132,921 Source: BCC, Inc., ChemQuest

2009

2010

2015

95,000 42,000 137,000

96,995 42,840 139,835

119,708 49,662 169,370

CAGR% 2010-2015 4.3 3.0 3.9

TABLE 3 MARKET SECTORS FOR CONVENTIONAL COATINGS AND ADHESIVES (2009) ($ MILLIONS) Market Construction Product Sector Assembly Coatings 54,150 25,650 ($) Coatings 57.0 27.0 (%) Adhesives 10,500 7,560 ($) Adhesives 25.0 18.0 (%) Total ($) 64,650 33,210 Total (%) 47.2 24.2 Source: BCC, Inc., ChemQuest

Packaging

Transportation

Other

Total

2,375

11,400

1,425

95,000

2.5

12.0

1.5

100.0

15,960

5,040

2,940

42,000

38.0

12.0

7.0

100.0

18,335 13.4

16,440 12.0

4,365 3.2

137,000 100.0


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TABLE 4 OVERVIEW OF GLOBAL COATINGS MARKET TOP COMPANIES WITH EARNINGS OVER $100M (2009) (#) Company

(1) AkzoNobel N.V. (2) PPG Industries (3) Henkel AG & Co. KGaA (4) The Sherwin-Williams Company (5) DuPont

Location

Amsterdam, Netherlands Pittsburgh, PA/USA

Coatings Revenues ($ millions) (2008) 14,124 10,935

Coatings Related Market Segments (% where available) Decorative Paints:34% Performance Coatings:29% Performance Coatings:30% Industrial Coatings:25% Architectural Coatings:14% Adhesives Technologies:47%

Düsseldorf, Germany Cleveland, OH/USA Wilmington, DE/USA Ludwigshafen, Germany

9,849

Medina, OH/USA Minneapolis, MN/USA Baar, Switzerland Osaka, Japan Osaka, Japan

3,643

St. Paul, MN/USA

2,200

(13) Jotun AS

Sandefjord, Norway

1,870

(14) DAW

OberRamstadt, Germany Taylor, MI/USA

1,471 1,440

Decorative Architectural Products:17%

(16) The Comex Group

Mexico City, Mexico

1,400

(17) H.B. Fuller Company

St. Paul,

1,391

Architectural: 75% Industrial: 15% OEM: 5% Auto refinish: 5% North America:45%

(6) BASF Group (7) RPM International Inc. (8) The Valspar Corporation (9) Sika AG (10) Kansai Paint Co., Ltd. (11) Nippon Paint Co., Ltd. (12) 3M

(15) Masco Corporation

6,521 4,300 3,729

3,168 2,356 2,299 2,276

Paint Stores Group:61% Global Finishes Group:23% DuPont Coatings & Color Technologies:22% Chemicals:17% Plastics: 16% Performance Products:14% Functional Solutions:15% Industrial Segment: 63% Consumer Segment: 37% Coatings Segment:59% Paints Segment:32% Construction Segment:80% Industry Segment:20% Paint Segment:100% Coatings Materials: 95% Industrial & Transportation Health Care Safety, Security & Protection Consumer & Office Decorative :14% Paints:28% Coatings:47% Powder Coatings: 11% Architectural/Decorative: 100%


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MN/USA (18) Hempel A/S

Kgs. Lyngby, Denmark

1,347

(19) Beckers

Hoganas, Sweden Mumbai, India

1,316

Toronto, Ontario, Canada Tokyo, Japan

1,053

(20) Asian Paints Limited

(21) Shawcor (22) Chugoku Marine Paints

1,062

1,036

(23) Kemira Oyj (Tikkurila)

Helsinki, Finland

953

(24) Benjamin Moore

Montvale, NJ/USA

835

(25) Dai Nippon Toryo

Osaka, Japan

802

(26) Brillux GmbH and Co. KG

Muenster, Germany

662

(27) Forbo

Baar, Switzerland

606

(28) Orica

Melbourne, Australia

555

(29) Helios

Domzale, Slovenia

520

(30) Fujikura Kasei Co. Ltd.

Tokyo, Japan

500

(31) Arch Chemicals, Inc.

Norwalk, CT/USA

463

Europe:30% Latin America:16% Asia Pacific:8% Marine Protective Container Yacht Decorative Industrial Coatings: 81% Art Materials: 19% Architectural/Decorative: 90% Industrial & Automotive: 10% Pipeline & Pipe Services Petrochemical & Industrial Marine Paints Industrial Paints Container Paints Adhesive Coatings:23% Pulp & Paper:37% Specialty:13% Architectural Paint Industrial Automtove OEM Auto refinish Marine Decorative/architectural Paints Lacquers Varnishes Adhesives Flooring Systems: 46.5% Bonding Systems: 34.1% Mining Services Chemicals Consumer Products Decorative coatings: 27% Synthetic resins: 22% Car refinishes: 14% Metal coatings: 13% Coatings for plastics Architectural coatings Electronic materials Polymers and resins Industrial Biocides: 21% Wood Protection/Industrial Coatings: 31%


12


(32) Freeworld Coatings

Johannesburg, South Africa North Ryde, Australia

364

(34) Berger Paints India Ltd.

Kolkata, India

352

(35) Teknos Group Oy

Helsinki, Finland Surrey, British Columbia, Canada Philedelphia, PA/USA Los Angeles, CA/USA Abu Alanda, Jordan

346

(40) JW Ostendorf GmbH & Co. KG

Coesfeld, Germany

320

(41) CIN Group

Maia, Portugal

319

(42) Dyrup A/S

Soborg, Denmark Wesel, Germany

316

(44) Kelly-Moore

San Carlos, CA/USA

281

(45) Flugger Group

Roedovre, Denmark Wels, Austria

281

Bangkok, Thailand

227

(48) Industrias Titan S.A.

Barcelona, Spain

223

(49) Shinto Paint Co. Ltd.

Amagasaki, Japan

220

(33) The Wattyl Group

(36) Cloverdale Paint Inc. (37) Rohm & Haas Co. (38) Dunn Edwards Corp. (39) National Paints

(43) Altana AG

(46) Tiger Coatings GmbH & Co. KG (47) TOA Group

359

340 330 329 328

315

250

Performance Products: 14% Decorative Coatings Performance Coatings Industrial Marine Decorative/architectural Decorative Automotive Industrial Industrial coatings Architectural coatings Architectural coatings Wood coatings Powder coatings Powder coatings Architectural coatings Industrial coatings Architectural/decorative Industrial Automotive Marine Decorative Coatings Architectural/decorative: 59% Auto refinish: 3% Industrial: 18% Protective: 16% Other: 4% Decorative coatings Wood coatings Coatings & Sealants Effect Pigments Architectural coatings: 80% Industrial coatings: 10% Non-auto OEM: 10% Architectural/decorative: 100% Powder coatings Masterbatches Architectural/decorative Protective coatings Marine coatings Wood coatings Decorative/architectural Industrial maintenance Marine coatings Powder coatings Fine arts products Architectural/decorative Industrial maintenance


13


(50) Rock Paint

Osaka, Japan

219

(51) KCC

Seoul, South Korea

211

(52) Yasar

Izmir, Turkey

200

(53) Renner Sayerlack

Cajamar, Brazil

197

(54) FLH Group

Arbon, Switzerland

190

(55) Yung Chi

Kaohsiung, Taiwan

189

(56) Boero Group

Genoa, Italy

186

(57) Boysen

Quezon City, Phillipines

183

(58) Grebe Group

Weilburg, Germany

178

(59) Tambour

Netanya Souty, Israel

170

(60) ICA Group

Civitanova Marche, Italy

154

(61) Inver SpA

Bologna, Italy

153

(62) Tohpe (63) Diamond Vogel Paints

Osaka, Japan Orange City, IA/USA

152 145

(64) Empils

Rostov-onDon, Russia

141

Other Total Source: Coatings World

2,150 95,000

Automotive OEM Automotive coatings Industrial coatings Marine & container Automotive Industrial Decorative Architectural coatings Industrial Automotive OEM Auto refinish Wood coatings Architectural coatings: 5% Industrial coatings: 15% Automotive OEM: 1% Auto refinish: 2% Wood coatings: 50% Non-stick coatings: 10% Packaging coatings: 17% Architectural/decorative Marine Industrial Arch./Deco.: 64% Yacht: 19% Marine: 17% Architectural/decorative Industrial coatings: 40% OEM (non-auto): 40% Rail & defense: 20% Decorative paints Industrial paints Marine paints Sealants Adhesives Industrial wood coatings: 95% Industrial: 95% Architectural/decorative: 5% Paints, Lacquers, Adhesives Architectural coatings Industrial coatings Heavy duty coatings Traffic coatings Arch./Deco coatings: 81% Industrial: 9% Various


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NANOCOATINGS Nanocoatings have the potential for enhancing the performance and durability of an extensive array of manufacturing processes, in addition to improving the items that they produce. They may thus enable significant energy savings to be realized across just about every market sector. With mounting concerns in regard to global warming and a myriad of other serious environmental issues there is a strong push toward the rapid development of many alternatives energy harvesting and generating technologies to displace fossil fuels. In the face of the dire predictions espoused by thousands of scientists worldwide indicating that we must act directly to have any hope of reversing the impending catastrophes that they articulate, we will most likely require any and all alternatives. The author feels that these factors in combination with the fact that anything we manufacture and almost every service that is provided requires some form of energy expenditure, will constitute a powerful driver for the nanocoatings markets, especially in the energy sector. Table 5 presents the global nanocoatings markets by region, and Table 6 displays these markets by business sector. Beyond the scope of the energy markets, nanocoatings will impart multifunctional attributes to many everyday consumer products. For instance, nanocoatings on cell phones may keep them waterproof combined the ability for harvesting power from ambient light. Smart nanocoatings on food packaging may convey the level of freshness of a contained product; release a preservative if required to maintain the integrity of the product; as well as to record and transmit tracking data in regard to the product’s shipping status, condition, and location. Nanocoatings on implanted medical devices may serve to render them biocompatible in conjunction with the selective release of therapeutic drugs should the nanosensors embedded within them be alerted to indications of infection. As the technology behind nanocoatings advances, we are likely to see increasing expectations that multi-applicability and multi-functionality will be considered the norm.


15


TABLE 5 GLOBAL NANOCOATINGS MARKET BY REGION THROUGH 2015 ($ MILLIONS) Region North America Central America South America European Union and ROE Middle East East and Southeast Asia Central Asia South Asia Africa Oceania Total Source: BCC, Inc.

CAGR% 2010-2015

2008

2009

2010

2015

353.1 12.4 80.2 316.5

540.4 23.7 126.1 483.4

869.1 30.5 196.9 777.4

4,680.0 78.8 655.0 4,740.0

40.0 20.9 27.2 43.6

70.5 348.3

109.5 531.6

173.1 855.5

657.7 4,652.0

30.6 40.3

50.5 81.5 49.7 19.3 1,382.0

82.3 128.2 80.1 34.2 2,139.5

129.0 200.3 122.2 47.5 3,395.0

675.9 902.4 568.2 346.0 17,956.0

39.3 35.1 36.0 48.8 39.5

TABLE 6 GLOBAL NANOCOATINGS MARKET BY SECTOR THROUGH 2015 ($ MILLIONS) Sector Under Development (UD) In Production (IP) Transportation (IP) Construction (IP) Health Care (IP) Electronics (IP) Energy (IP) Military and Security (IP) Textiles (IP) Commercial (IP) Total Source: BCC, Inc.

2008

2009

2010

2015

306.8 64.9 79.9 34.5 164.9 158.9 218.3 353.8 1,382.0

503.7 129.6 149.8 52.2 209.0 250.8 321.9 522.5 2,139.5

651.8 234.2 352.4 101.8 275.8 404.0 600.9 774.1 3,395.0

2,154.7 987.6 2,354.0 610.5 4,307.7 1,993.1 2,477.9 3,070.5 17,956.0


CAGR% 2010-2015 27.0 33.4 46.2 43.1 73.3 37.6 32.8 31.7 39.5

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NANOCOATINGS IN MEDICAL APPLICATIONS Applications for nanocoatings in the medical sector are likely to grow at a significant rate as they might be engineered to have profound benefits. Contingent on the specific application, they may quite literally make the difference between life and death. Rapid advances are being made in the development of dynamic nanocoated surfaces for orthopedic and other biomedical implants, biocompatible and drug eluting stents, as well as powerful antimicrobials, surgical, burn and wound closure. Table 7 gives a view of the global market for nanocoatings in the medical sector. Nanoparticle Coatings in Medicine The potential applications of nanoparticles in many facets of medicine are significantly enhanced when their surfaces are appropriately modified. These surface treatments are also useful in associated biological domains such as gene therapies, biosensor development, bioseparation, the immobilization of enzymes, and cell-recognition and targeting. State of the art nanoparticle surface modification can be accomplished via three different methods.

 In situ during synthesis.  Post synthesis by the appropriate addition (e.g., electrostatic binding) of

biomolecules. Limiting factors for this method are that the biomolecules may be stripped from nanoparticle surfaces under certain conditions, such as when they are immersed in environments that contain high salt concentrations or have high temperatures.  Chemical modification of nanoparticle surfaces utilizing the covalent binding of functional hydroxyl, carboxyl, and amino groups. To achieve specific molecular scale biological/chemical surface modifications, components with high affinities for one another are employed. Examples of these pairings include biotin/streptavidin, antibodies/antigens, and ligands/receptors.


17


TABLE 7 GLOBAL NANOCOATINGS MARKET IN THE HEALTH CARE SECTOR THROUGH 2015 ($ MILLIONS) Category Under Development (UD) In Production (IP) Antimicrobial Surfaces (IP) Antimicrobial Textiles (IP) Artificial Joints (UD) Catheters (temporary and implanted) (UD) Dermal Patches (UD) Endoscopes (UD) Medical/Dental Implants (UD) Plastic Surgery (UD) Stents (UD) Surgical Instruments (IP) Wound Dressings (IP) Wound/Surgical Closure (UD) Total Source: BCC, Inc.

CAGR% 2010-2015

2008

2009

2010

2015

11.7 8.9 9.1 6.3

19.2 15.2 15.9 10.0

49.5 30.1 35.5 23.0

288.9 207.7 312.5 193.2

42.3 47.2 54.5 53.1

2.0 4.5 9.6

6.5 10.3 15.7

17.1 21.5 36.7

112.1 94.4 318.0

45.7 34.4 54.0

1.2 6.1 3.2 9.3 8.0 79.9

5.3 11.2 6.5 18.5 15.5 149.8

12.4 44.3 12.8 37.3 32.2 352.4

94.5 272.3 98.7 250.5 111.2 2,354.0

50.1 43.8 50.5 46.4 28.1 46.2

Silica Nanocoatings for Core-Shell Nanoparticles Nanocoatings have vital roles to play in the medical applications of core/shell nanoparticles as the surface properties of nanoparticles are critical in medical diagnostics and therapeutics. Inert protective or specifically functionalized nanocoated “shells” are critical for imparting biocompatibility to their “core” nanoparticles when exposed to the multifarious in vivo environment of the human body. They can also serve to increase the chemical stability of, and confer unique optical, magnetic and mechanical properties to nanoparticles. Both organic and inorganic materials may be employed as nanocoatings and stable core-shell structure synthesis is dependant on the specific electronic charges of both the core and shell materials. These nanometric protective coatings impart photochemical stability to nanoparticles as well, whereby they act to limit the potential destructive effects on the core payloads (e.g., via photobleaching, oxidation, biodegradation). In gene and drug delivery they can retard nanoparticle clearance form the blood and provide them with stealth in regard to the immune system. Genetic material can easily be degraded by enzymes prior to arriving at its target site if it is not adequately Copyright© BCC Research, Wellesley, MA USA, Web: www.bccresearch.com/

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protected. These coatings are also imperative for medical applications that incorporate dyes, genes, and drug molecules, as there are a number of fluorescence “quenching” substances including oxygen and iodide ion that act to reduce nanoparticle fluorescence. Silica coated biocompatible nanoparticles can be synthesized via a water in oil microemulsion whereby silica shells are formed through the hydrolysis of tetraethoxysilane. These coatings can maintain the integrity of hollow “nanocarrier” encapsulated drugs in vivo as well as protect surrounding healthy cells from the toxicity of these drugs. Nanocoatings for Quantum Dots The surfaces of quantum dot semiconducting nanocrystal in vivo imaging agents (2 to 10 nm in diameter) can be coated to enable their targeting and binding to specific cells or tissues and to simultaneously offer visible evidence of their binding location within a patient. This verification can be relayed by color changes or through light diffraction and can serve as an enhanced alternative to conventional organic dyes for a myriad of fluorescence-based biosensing applications. Uncoated quantum dots are considered as toxic to biological systems, and hence negate their use for in vivo applications and biological assays in their unaltered state. For example, biologically toxic cadmium telluride (CdTe) quantum dots may be utilized as microscopic fluorescent beacons for imaging, drug delivery monitoring, and also to facilitate the controlled alteration of cellular components. In one study by researchers in Ireland, it was shown that the toxicity of the quantum dots could be diminished by incorporating gelatin during their synthesis; resulting in a more tolerable nanocomposite. Surface coatings are therefore important for reducing or ideally eliminating any toxic effects on cells both in vitro and in vivo, and any initiation of immune response. Quantum dots can be PEGylated, whereby poly(ethylene glycol) polymer chains are covalently bound to their surfaces to impart stealth capabilities, and hence can go undetected by the immune system A research team that is based in Switzerland has coated PEGylated quantum dots with sugar molecules (d-mannose and d-galactosamine) to selectively target the liver. This strategy has promising implications for the direct targeting of chemotherapeutic drugs to specific organs without accumulating elsewhere in the body. The group that is lead by Peter H. Seeberger conducted the study with mouse models and found that these sugars have affinities for receptors in the liver. In trials involving coated and uncoated quantum dots it was observed that the sugar molecule coated quantum dots accumulated in the liver at a three fold higher rate than the uncoated quantum dots.


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Quantum Dot Brain Probes In China, researchers have developed a means by which quantum dots coated with biodegradable poly(ethylene glycol)−poly(lactic acid) polymers may permeate the blood brain barrier and be employed for precise drug delivery to, and imaging of the brain. The polymer coated quantum dots were further endowed with targeting molecules from wheat germ agglutinin (a carbohydrate-binding protein) and conveyed into the brain via the nasal passage. The resulting nanoscale probes demonstrated good stability, high drug payload capacity and water-solubility, as well as safe and effective abilities for brain targeting and imaging. Utilizing the terminal groups that are made available via the quantum dot adhered polymers, many types of targeting, drug delivery, and imaging strategies might be realized to address numerous diseases of the central nervous system. Alkanethiol Self Assembled Monolayers (SAMs) Nature employs many spontaneous self-assembly strategies for the fabrication of molecular machines, from simple proteins such as globulins or histones to sophisticated and elegant DNA structures. Self-assembly processes require no outside intervention once they have commenced. Inherent organizational rules are “programmed” within the molecular structures of the components themselves, and are facilitated by local in vivo thermodynamics. The constituent parts of a given structure to be assembled have potent mutual affinities that utilize molecular recognition with a high degree of selectivity. Hence, the molecular subunits of the DNA duplex are spontaneously formed via self-assembly through the binding of complementary oligonucleotides (single strands of DNA). Self Assembled Monolayers (SAMs) are ultrathin (~1nm) self-assembling films that are automatically coated onto solid substrates when they are submerged in a solution that includes amphifunctional molecules. These molecules contain a head group, which has a strong affinity for solid surfaces, a tail (e.g., alkyl chain hydrocarbon), and a terminal group, which can be tailored to exhibit the desired surface attributes of the resulting monolayer. The molecular forces that exist between the tails are the main drivers toward the organization of the monolayer. Both the head and tail end groups can be chemically customized, thereby facilitating the generation of a wide variety of useful surface applications with molecular level control. Additionally, as molecular scale self-assembly can thus occur on large scale surfaces it follows that SAMs may serve as a relatively straightforward, albeit essential interface for connecting the nanoscale world with our macroscale world. The potential applications of SAMs, when applied to a myriad of substrate surfaces are quite diverse. They may include highly improved corrosion and wear resistance,


20


and enable highly sensitive biological and chemical sensing. SAMs might be particularly desirable when utilized for providing an interface between components in molecular electronics. The two most analyzed SAMs to date are silanes, which are employed to modify hydroxyl terminated surfaces (hydroxyls are molecules comprised of only an oxygen and hydrogen atom connected by a single covalent bond), and organosulphur compounds, which take advantage of sulfur’s affinity for noble metals such as gold, platinum, and silver. These metals make excellent electrodes for electrochemical sensors, especially gold. In medical applications, alkanethiol modified surfaces impart biocompatibility; can be used as an analogue biomembrane material; facilitate data acquisition and feedback related to electron transfer processes (molecular electronics); enable the fabrication of sensors; and can serve as a “molecular glue” for adhering nanometric components. SAMs can also provide a fundamental layer upon which multilayered molecular systems may be fabricated to include such elements as DNA, nanotubes and other fullerene species, as well as quantum dots and a variety of nanoparticles. Nanocoating Methods for SAMs There are several strategies for the application of SAMs to surfaces. These include:

 Micro Contact Printing: Used to transfer SAMs patterns to surfaces using a polydimethylsiloxane (silicon-based organic polymer) stamp which transfers a thiol “ink” to metals in a few seconds.  Patterning: The SAMs deposition of nanoscale features and patterns having varied surface chemistries are a critical requirement for nanotechnology applications, which encompass biosensors, micro/nanoelectronics, and optical mechanisms such as displays and waveguides. The majority of these applications necessitate the fabrication of the smallest possible features sizes ranging from centimeters to 20 nm. There are two approaches to patterning: a) Composition: SAMs features/patterns can be integrated during assembly via dip-pen lithography or micro contact printing. b) Decomposition: Sections of pre-deposited SAMs materials are judiciously removed (e.g., by photolithography, electron beam writing, or micromachining), to allow additional components to be added. c) Nanoshaving: A newer technology that can achieve selective mechanical breaking of molecular bonds in SAMs using an Atomic Force Microscope tip. Partial or complete displacement of the SAMs (to bare metal) can be accomplished with a resolution of 20 nm. If the nanoshaving is conducted in a solution containing a second alkanethiol, the exposed metal will be coated with the second component. This is known as nanografting.


21


Crystal Seeding with SAMs SAMs makes possible a means for controlling the nucleation and growth of single crystals. This enables capabilities for directing the position of individual crystals and even the organization of crystal species on SAMS modified substrates. This capacity may be of considerable value for the fabrication of ordered arrays of nanoparticles. Researchers at Georgetown University, in Washington DC used SAMs templates that were submerged sequentially in two types of solutions for the oriented growth of crystals. The 4'-iodo-4'-nitrobiphenyl (INBP) polar crystals they employed grew into different shapes depending on the crystal growth solution used. In this study the crystals formed prisms in an ethanol/methylene chloride solution, and elongated needles developed in a benzene solution. This work demonstrated that crystals with predictable geometries can be synthesized by utilizing SAM templates that have chemical and geometric compatibilities. Biosurfaces Enabled with SAMs Nanostructured surfaces that are engineered to operate with biological entities will be in great demand for applications such as medical implants, biosensors, and the development of drugs. SAMs can serve as a crucial model system for increasing our knowledge of protein adsorption kinetics, as its surface properties can be well defined and modified in a controllable way. Protein adsorption plays a fundamental role as a precursor for cell adhesion, which is essential for implants and for the controlled growth of cells on surfaces. The careful adhesion of proteins to substrates that allows them to maintain their natural states and functions will be of significant value toward the development of advanced biosensors. The direct contact of proteins to metal surfaces will initiate denaturation. Hence, for the synthesis of active protein surfaces SAMs may facilitate molecular control over their immobilization, as well as to provide an insulating layer between the proteins and the metal. SAMs can make possible the immobilization of large numbers of cells as well as organize their distribution and orientation on surfaces. This can be accomplished by first adsorbing one or more proteins of the extracellular matrix, which may include fibronectin, elastin, laminin, herapin, tenascin, vitronectin, or collagen to a SAM surface to assist with the attachment of cells. Many types of cells bind to the extracellular matrix by employing specific surface cellular adhesion molecules that reside on their exteriors called integrins. A number of important applications may then be made possible utilizing the individual cells that are tethered to SAM protein surfaces. Examples include investigations into how cells interact with target molecules for the testing of drug candidates, genetic engineering, and toxicological studies.


22


SAMs-Based Biosensors The most prevalent applications of SAMs in the biosensing field are in electrochemical diagnostic sensors, which involve the coating of organosulfur SAMs on electrodes. A typical biosensor entails the integration of recognition molecules with (usually) a gold signal transducer, whereby the attached and immobilized recognition elements endow the sensor with the capacity for precise discrimination between analyte species to be sensed. Examples of biological recognition elements are macrocyclic or other types of ligands, microbes, enzymes, receptors, DNA, antibodies, organelles, membranes, cells, and tissues. Transducers include electrochemical, bulk or surface acoustic wave, optical, calorimetric, surface force charges, or mechanical stress. A process that is critical for the fabrication of biosensors is the immobilization of the recognition elements. This is typically achieved by either capturing or chemically binding the recognition molecules within a polymeric membrane. This technique is left wanting, however, as its lacks specificity insofar as the control of the location and concentration of the recognition elements. When an electrodes are coated with SAMs on the other hand, they permit the molecular level structuring of the interface; the precise positioning of recognition elements; and hence the ability to sense analytes with a high degree of resolution. BIOMEDICAL IMPLANTS The medical implant market in the U.S. is estimated to be $23 billion per year and is expected to grow at a rate of 10% per annum over the next several years. The range of implants encompasses implantable cardioverter defribrillators, cardiac resynchronization devices, stents, heart valves, pacemakers, tissue and orthopedic spinal implants, hip and knee replacements, and intraocular lens implants. Materials that are selected for use in biomedical implants possess the desired attributes of mechanical strength and biocompatibility. Table 8 depicts the perceived global markets for nanocoatings applied to medical and dental implants, and artificial joints In the case of orthopedic implants, (e.g., knee and hip replacements, shoulder and thoracolumbar implants, spinal spacers), their wear properties at interfacing surfaces are currently inadequate. This can lead to the localized generation of particulates near to the wear interface, increased discomfort or pain for the patient, and eventual implant failure, which involves the surgical removal and replacement of the implant. Orthopedic implant surfaces can be modified by techniques that involve the deposition of additional material such as thin coatings, or the implantation of energetic ions to alter local atomic bonding. Functionally graduated and/or multilayered nanocoatings can be applied to provide a gradual transition


23


from the bulk material to a very smooth and tough wear surface. These nanostructured materials exhibit enhanced mechanical, electronic, optical, and magnetic attributes in contrast to their corresponding bulk forms. Nanoscale materials contain a large proportion (50%) of defects such as grain and interphase boundaries, and dislocations that strongly impact their physical and chemical characteristics. For example, the hardness of electrodeposited nickel (as calculated by the Vickers hardness test) increases from 140 to 650 when the grain size is reduced from the microcrystalline size range (from tens of nanometers to microns), to nanocrystalline (10 nm). Likewise, nanostructured ceramics are stronger and tougher than their larger grained counterparts. A hard composite coating comprised of nanocrystalline (10-50 nm) grains of titanium carbide (TiC) that were embedded within a amorphous carbon matrix (at 30%) exhibited a fourfold increase in toughness over single-phase nanocrystalline TiC. For medicine, the controllable synthesis of materials at the nanoscale makes available a diverse range of new properties that were previously thought as unachievable. Hence, intense efforts are proceeding with global scope to take advantage of the potential opportunities that are presented through the use of nanomaterials and nanocoatings. TABLE 8 GLOBAL NANOCOATINGS MARKET FOR MEDICAL/DENTAL IMPLANTS AND ARTIFICIAL JOINTS THROUGH 2015 ($ MILLIONS) Implant Type Under Development (UD) In Production (IP) Biliary Stent (UD)

CAGR% 2010-2015

2008

2009

2010

2015

1.1

1.5

11.4

74.1

45.4

Catheter (cardiovascular) (UD)

3.5

5.0

9.9

95.2

57.3

Catheter (temporary) (UD)

1.6

2.6

6.4

52.9

52.6

Catheter (urinary) (UD)

1.2

2.4

6.7

45.1

46.4

Cochlear Implant (UD)

1.0

1.9

3.0

22.4

49.5

Coronary Stent (UD)

5.0

9.7

32.9

198.2

43.2

Dental Implant (UD)

2.3

3.5

10.2

86.5

53.3

Drug Pump (UD)

0.7

1.1

3.5

25.8

49.1

Heart Valve (UD)

1.4

2.0

4.2

47.3

62.3

Hip Replacement (UD)

2.2

6.4

12.2

105.0

53.8

Intraocular Lens Implant (UD)

1.5

2.2

3.6

21.8

43.4

Knee Replacement (UD)

4.2

7.2

14.3

136.7

57.1

Orthopedic Pins, Rods, Screws,

1.1

1.5

3.7

38.4

59.7


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and Plates (UD) Pacemaker (UD)

1.7

2.2

3.5

48.5

69.2

Plastic Surgery Implant (UD)

0.9

1.3

5.5

27.3

37.8

Spinal Implant (UD)

1.7

2.3

9.0

70.8

51.1

31.1

52.8

139.5

1,096.0

51.0

Total Source: BCC, Inc

Nanostructured Diamond Coatings for Biomedical Implants The global artificial joints market was valued at $12.2 billion in 2008 and is expected to grow by more than 9% annually to reach $22.2 billion by 2015. The number of total hip implants in the U.S. was about 250,000 in 2008. The number of revision total hip replacements is expected to increase at a rate of from approximately 47,500 in 2008 to 96,700 in 2030 accounting for over a 103% increase. The number of revision total knee replacements is expected to increase at a rate of from 65,900 in 2008 to 268,200 in 2030, accounting for a 307% increase. These increases may be attributed to the growing ranks of aging baby boomers, additional younger individuals who are increasingly opting for these procedures, combined with new innovations related to these implants that are making them more attractive. There are approximately 150-200 types of hip prostheses on the market, and an uninsured individual in the U.S. today will pay about $45,000 for a total hip replacement procedure. There is a large demand for coatings technologies for artificial joints that might reduce the friction and wear at the interfaces of mating components and to increase the service lifetimes of the implants. The current typical hip prosthesis lifetime is about 10-15 years, with most complications being associated with the loosening of components, the formation of small gaps between natural bone and the implant leading to lack of mechanical stability, reduced joint movement and “squeaking”, osteolysis, negative bioreactions, and pain increases, leading to implant failure. In many instances hip joint resurfacing or revision surgery is required, particularly in younger more active patients. Significant improvements in the long term prognosis for many hip and knee replacement patients could be realized if the wear surface lifetimes of the implants could be increased by diamond or diamond-like nanocoatings. In the U.S., the hip resurfacing market was $57.3.million in 2008, and is predicted to increase by 36% per year toward $483 million by 2015. It has been demonstrated that the wear on implant component surfaces is noticeably reduced when coated with ceramic materials such as zirconium dioxide in contrast to metal materials. There exist a number of shortcomings, however, that are inherent to ceramic-based implant devices, which include fragility, cracking, structural fabrication limitations, and instances of complete failure. Nanostructured bioengineered diamond coatings on cobalt/chrome/titanium alloys may increase Copyright© BCC Research, Wellesley, MA USA, Web: www.bccresearch.com/

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biomedical implant device lifetimes for up to 40 years due to their extreme hardness, low friction, wear resistance, and biocompatibility Implanted Orthopedic Monitoring Devices Researchers led by Dr. Tom Webster at Brown University (Providence, RI) are investigating carbon nanotube coated titanium orthopedic implants that might monitor the healing process and expedite bone growth. A battery operated titanium implant could run a low level current between the surface bound nanotubes, which can be quantified. Depending on the degree of resistance between the nanotubes a correlation could be made as to the healing status of an injured or post operative site. For example, the existence of healthy bone material might be indicated by strong conduction between the nanotubes, whereas infection might be revealed by a greater resistance and scar tissue even more so. The coating process involved anodizing the surface of the titanium implant with hydrofluoric acid and then applying an electric current, which caused the formation of 100nm deep pits. A cobalt catalyst was then added to the surface and heated, which initiated the nanotube growth. It was found that when human bone cells (osteoblasts) were added to the coated implant they grew twice as fast as for the uncoated titanium, which may have been due to the electric current. The nanotubes also had the capacity for identifying what was growing on the implant. This data may be conveyed to a handheld device using radio frequencies. Contemporary methods for monitoring implants include the relatively infrequent use of X-rays, which do not have the sensitivity required to distinguish new bone growth. When this technology matures, it might be able to monitor new bone growth in real time and have the ability to controllably elute drugs to speed the healing process as well. The implant has not as yet, however, been tested in vivo. Extensive testing for safety must be first undertaken in animal models to ensure that no nanotubes are released from the implant. Nanostructured Metalloceramic Coatings The primary components used in a total hip replacement include an ultrahigh molecular weight polyethylene acetabular cup interfaced with a metallic (Co-Cr-Mo alloy) femoral head. Although this combination has been employed for the last 30 years, premature wear has been an issue. A novel functionally graded nanocrystalline coating called IonGuard® for Co-Cr-Mo components has been developed by Spire Corporation (Bedford, MA). A multilayered transitional coating is applied by ion beam assisted deposition, which consists of initial metallic layers that are capped by a hard, 10 nm thick nanocrystalline ceramic outer coating. An


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initial metallic layer at the substrate interface increases adhesion to the cobalt chrome surface, while the covalently bonded outer layer facilitates scratch and wear resistance. Thin interleaved chromium deposits increase adhesion between the layers to increase the strength of the overall coating; acting as a barrier to prevent crack development and propagation. Dental Implant Nanocoatings It is estimated that there are approximately 10 to 15 million individuals in the U.S. that suffer pain and dysfunction due to temporomandibular joint and muscle disorders (TMJ). TMJ refers to a medical/dental condition in which pain and discomfort affect the temporomandibular joint and/or the connecting muscles and adjacent tissues that connect the upper and lower jaw. In total TMJ replacement both the upper temporal bone socket (articular fossa) and the mating ball-shaped ends (condyles) of the jawbone are replaced. From 1988 to 1998, an estimated 100,000 TMJ patients received implanted plastic alloy implants devices. However, they have shown very high failure rates. Hence new designs will require the incorporation of highly wear resistant surfaces in conjunction with materials that are biocompatible with existing bone. Nanostructured diamond coatings that are synthesized via CVD show particular promise as they are ultra hard and tough and have good adhesion to titanium alloys. Hence, significant improvements may be seen by coating the ball and socket wear surfaces of TMJ implants with very hard and smooth diamond nanocoatings. A condoyle implant made of Ti-6Al-4V alloy coated with 3 µm thick layer of nanostructured diamond was subjected to 400,000 load cycles (equivalent to 4.4 years normal use) in a mandibular movement simulator. The root mean square (statistical calculation for determining the extent of a changing quantity) surface roughness of the uncoated control varied from 50.3 nm to 248.4 nm, whereas the diamond coated surface varied from 61.5 nm to 122.7 nm. A scanning electron microscope verified that there was far greater wear on the uncoated titanium surface than the diamond coated surface. Biocompatible and Corrosion Resistant Diamond Coated Implants A number of attractive features inherent to diamond nanocoatings are that they have high electrochemical resistance and show stability in corrosive environments. When the coatings are doped with boron they exhibit quasi-metal electrical activity. Using a scanning reference electrode technique, Dowling and co-workers at the Ceramics Research Centre, (Dublin, Ireland) discovered that a diamond-like carbon coating on AISI 316L surgical grade stainless steel showed more than a fourfold greater electrochemical resistive capacity than an uncoated sample.


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To determine the in vivo biocompatibility of diamond nanocoatings on the Ti-6Al-4V alloy a study was conducted by J. E. Lemons at the University of Alabama (Birmingham, AL) using four New Zealand white rabbits. It was demonstrated that the diamond coating had outstanding biocompatibility. Living tissue had grown across its surface; there was no fibrous granulation tissue; foreign body reactions; or abnormalities in the bone or bone marrow spaces. In biocompatibility trials using Tyrode’s solution (a salty fluid that has properties similar to that which exist within the human body) Mitura et al, at the Technical University of Lodz, (Lodz, Poland), showed that nanocrystalline diamond coatings had a high tolerance against chemical attack. In another set of trials to validate biotolerance, diamond coated AISI-316L stainless steel discs were implanted into the chest muscles of guinea pigs. The results indicated good biotolerance and compatibility with tissues with effective shielding against corrosion. Hydroxyapatite Nanocoatings Hydroxyapatite (HA) is a bioactive calcium phosphate ceramic that has a crystal structure similar to that of natural teeth and bone materials. Nanocoatings comprised of HA are therefore ideal for applying to the surfaces of ceramics and metallic implant components as they will promote improved attachment and bonding to bone and surrounding tissues. The high density makeup of the nanostructured HA coating demonstrates good osteoconductive properties (e.g., promotes bone formation around an implant), cilitates the binding of specific proteins, and mineralization. Zirconia nanocrystals may be added to further reinforce the HA compound and increase its fracture and bending strength for load bearing implants. Almost all conventional bioceramic coatings for dental implants are plasma sprayed, but are prone to inherent fracturing, porosity, and random dissolution rates. These relatively thick coatings (40-80 µm) are subject to fragmentation upon insertion of implant anchor screws. This is due to the exceedingly high temperatures (>10,000°C) that are necessary for melting the raw material. Two new potential techniques exist (ion beam sputtering and pulsed laser deposition) for the application of high quality HA coatings in a vacuum chamber. Ion beam sputtering gives superior bond strength and density and allows for the creation of nanocrystalline coatings when followed by proper heat treating. Advantages of synthesizing these coatings under vacuum are that they can be built up in very small increments, even by individual atoms. In both methods material is detached from a pressed HA target via beam bombardment (e.g., by an argon ion beam or by laser) to grow nano-sized crystals instead of micro-sized particles as in the plasma spray process.


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Researchers at the University of Alabama have employed multilayered nanostructured coatings to improve the wear lifetimes of TMJ implants by gradually transitioning from a metal core to a smooth nanostructured ceramic surface. The screws that attach the implant to the bone was treated with a nanostructured hydroxyapatite coating to facilitate better implant adhesion to existing bone, to accommodate shear stresses, and to assist with the generation of new bone. Polyelectrolyte Multilayer Orthopedic Nanocoatings Investigations into the wear properties of conformal polyelectrolyte multilayer (PEM) nanocoatings were conducted by Pavoor et al, at MIT, (Cambridge, MA). Their structures can be simply tuned and they showed good adherence to most metal, plastic, and ceramic surfaces. The several hundred nanometer thick coatings were fabricated via the sequential adsorption of poly(acrylic acid) and poly(allylamine hydrochloride). The researchers noted that care must taken in the formulation of the nanocoatings to endow them with resistance to potential degradation by in vivo physiological pH and ions. The wear strength of these coatings was validated by using a pin-on-disk test whereby a stationary spherical "pin" is in contact with a rotating disc under an adjustable applied load. After 500,000 cycles of bi-directional motion it was found that the nanocoating reduced wear by up to 33% in contrast to an uncoated control. Hence, these trials show promise for their use in a wide range of orthopedic implant applications. Synthetic Diamond Nanocoatings The first atomic resolution of a diamond coated surface was by Tsuno, et al in 1991. Synthetic diamond coatings (thin films) may be grown by chemical vapor deposition (CVD) that hold an extensive range of promising nanotechnology applications when integrated into sensors, electronic circuitry, and microelectromechnical systems (MEMS), and as field emitting electron sources. Diamond coatings are currently applied commercially to cutting tools, heat dissipaters, optical windows and the diaphragms of speakers. The surface attributes of diamond include extreme hardness, high thermal conductivity, wide bandgap, optical transparency (infrared to UV), high field emission current, and low frictional coefficient. Table 9 details the primary properties of diamond.


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TABLE 9 CVD DIAMOND FILM PROPERTIES Property Hardness (Knoop) Strength, Compression Strength, Fracture Strength, Tensile Atom Density Density Young's Modulus Poisson's Ratio Coefficient of Friction Sound Velocity (20°C) Debye Temperature (0-800°C) Electron Mobility (25°C) Dielectric Constant (45MHz-20GHz) Hole Mobility Band Gap Loss Tangent Electrical Resistivity Dielectric Strength 105V/cm Heat Capacity (25°C) Thermal Conductivity (25°C) High Grade Medium Grade Low Grade Graphitization in inert atmosphere (or vacuum) Oxidation Refractive Index Optical Dispersion Optical Absorption Source: Applied Diamond, Inc.

Value Mechanical Properties 5,700 >110 1,000 0.5-1.4 1.77x1023 3.515 900-1,100 0.069 0.035-0.30 Electronic Properties 17,500 1,860 480 5.6

Units kg/mm2 GPa MPa GPa cm3 gm/cm3 GPa dimensionless dimensionless m/s °K cm2/Vs dimensionless

1,600 5.45 tan d = 2×105 at100 Electrical Properties >1014 107 Thermal Properties 0.510 ASTM Flash Method 1,800 1,100 700 1,500 600 Optical Properties 2.417 0.044 < 0.04 (10.6)

cm2/Vs eV GHz ohm-cm V/cm J/g-K W/mk W/mk W/mk °C °C

dimensionless dimensionless cm-1 (µm)

A variety of pathways exist for the synthesis CVD nanostructured diamond films, but what they all share is the deposition of nanometric grains and a resulting coating surface that is an order of magnitude smoother than that of microcrystalline coatings. A typical impurity in natural diamond is nitrogen, which can impact its transparency and conduction of electricity and heat. However, for CVD diamond nanocoatings the addition of minute volumes of nitrogen at concentrations of about Copyright© BCC Research, Wellesley, MA USA, Web: www.bccresearch.com/

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40-200 ppm, enhances their properties insofar as enhancing field emission and toughness. The coatings can also be tailored to have superior adhesion on metallic surfaces and extreme hardness in the range of 10-100 GPa (gigapascal). A method for the production of diamond was developed by GE in 1955. This technique involved the introduction of solid carbon into a liquid melt at high temperatures (1,500-2000°C) and high pressures (50-100 kbar, or 725,188.71,450,377.4 lbs/sq2). These synthetic diamond coatings were used primarily in abrasive and cutting tool applications. The chemical vapor deposition technique was first demonstrated by W.G. Eversol at Union Carbide Corp. in 1952. Diamond was grown on diamond seeds using carbon monoxide gas at temperatures of 900-1000°C with pressures of 1,469-4,407 lbs/sq2. The implementation of chemical vapor deposition for the growth of diamond films/coatings began in earnest during the 1970’s and 1980’s. At this stage the growth of diamond was possible in high volumes at lower temperatures (7001000°C) under vacuum pressures of (30 Torr, or 0.039 atmospheres), utilizing hydrogen and a carbon containing gas like methane. This method of diamond synthesis is compatible with microfabrication techniques and is scalable to large areas. Additionally, the growth parameters of CVD (e.g., gas species, substrate temperature, and bias-enhanced nucleation, which controls surface roughness and morphology) can be tailored to synthesize a range of carbon based coatings with useful properties including amorphous diamond, amorphous carbon, tetrahedral amorphous diamond, diamond-like carbon, and nanocrystalline diamond film. The last two decades have seen a significant spike in the interest of possibilities for the growth and control of properties in diamond coatings. Diamond growth thickness rates have increased from 1 µm/hr in the 1980’s at a cost of $5,000/carat to 150 µm/hr (300 µm/hr has been attained, and 1mm/hr may be achievable) at a cost of below $5/carat in 2009. High quality and free standing polycrystalline diamond films can be grown on a wide assortment of substrates including silicon, silicon dioxide, molybdenum, tungsten, nickel, copper, and tantalum at thicknesses of up to 2mm and 6” in diameter. The diamond coatings market has been limited by several factors including the high cost of growing and polishing, and poor coating adhesion and roughness. Poor adhesion is caused by differences in thermal expansion coefficients between diamond and tool substrates. There have been improvements, however, via the lowering of growth temperatures and the utilization of diffusion barriers. Thick high quality polycrystalline diamond or single crystal diamond coatings include cutting tool inserts, metal cutting, wire drawing, drilling, and as wear parts,


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optical, and electronics applications. Thin film diamond coatings have applications in UV photodetectors, electrodes, surface acoustic wave (SAW) and field emission devices, pressure and acceleration sensors, microelectromechanical systems (MEMs), Xray lithography masks, and Atomic Force Microscope (AFM) probes. Diamond films used for hydrogen, oxygen, and carbon monoxide sensors can operate in extreme environments at high temperatures. Boron doped diamond films exhibit piezoelectric resistance that is altered with mechanical strain. The surfaces of diamond coatings are known to be hydrogen terminated after growth, which resists wear and friction. They therefore have potential for medical implants. In Russia, in the 1970’s, Fedseev et al in showed that atomic hydrogen could simultaneously stabilize the diamond growth surface, selectively remove graphitic and other non-diamond carbon, and create new growth sites on the surface. These conditions enable much higher growth rates and allow the nucleation of new diamond nanocrystals on surfaces other than diamond. When the coating is annealed at 1,000°C in ultra high vacuum the hydrogen termination will be eliminated to result in a clean surface. Oxygen terminated diamond surfaces are non-conducting and hence, can be used as field effect transistors. Clean diamond surfaces on the other hand, are highly reactive and can be adsorbed with organic molecules to enable chemical and biological sensors and molecular electronics. Carbon Nanotube Coatings Chemical vapor deposition is amenable for the growth of carbon nanotube coatings comprised of single walled nanotubes (SWNT), multi-walled nanotubes (MWNTs) or multi-walled nanofibers (MWNFs), as free standing microscopic “mats” or “towers” on a variety of homogeneous substrates (e.g., silicon, quartz, mica, and pyrolytic graphite). Carbon nanotubes can also be grown on patterned surfaces, allowing for the fabrication of field emitters, sensors, and other electronic devices. MWNFs can be physically isolated and mechanically stabilized when silicon dioxide is used to fill the spaces between them. They can then be utilized as biosensors whereby DNA strands are attached to the tips of the individual fibers. One method for the thermal CVD growth of carbon nanotubes occurs when a hollow quartz tube that is 1” or 2” in diameter, is inserted into a tubular furnace at 5001,000°C. A substrate is placed inside the quartz tube while a hydrocarbon gas (e.g., carbon monoxide, methane, ethane, ethylene, or acetylene) is metered through the system. Typical nanotube growth rates can range from a few nm/min to 2-5 µm/min and can be directed by an electric field in situ to form, for instance, a connector between two electrodes in a microcircuit. Hot filament, microwave plasma-assisted CVD (MPCVD), as well as plasma enhanced CVD (PECVD) systems have been show to successfully grow multi-walled


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nanotubes (MWNTs) and multi-walled nanofibers (MWNFs). Transition metal “seeds” (e.g., Fe, Ni, Co, or Mo) are bound to the surface of a substrate and serve as the catalysts required for the growth of single walled nanotubes (SWNT), MWNT, and MWNF. There is a correlation between the dimensions of the catalysts and the diameters of the resulting nanotubes. When a hydrocarbon (e.g., methane) is adsorbed by a catalyst particle residing on the substrate surface, carbon is released upon decomposition, which is then dissolved and dispersed into the particle surface. When a supersaturated state is attained the carbon atoms self-assemble into a crystalline tubular structure. There have been two potential strategies put forward as relates to the ensuing growth kinetics: 1) If the catalyst particle is strongly bound to the substrate surface the carbon atoms, comprising the nanotube, emanate from the top surface of the particle, which remains anchored to the surface. (base growth model) 2) If the catalyst particle is not securely bound to the substrate surface the carbon atoms emanate from the bottom of the particle, which is then lifted from the surface as the nanotube grows. (top growth model) Infection Resistant Ventricular Assist Driveline There are about one million people worldwide who suffer from end-stage heart failure. For the many patients awaiting donor hearts and transplantation, the use of ventricular assist devices (VADs) has become an ideal interim, or in some cases, alternative treatment for these patients. According to a report by Global Industry Analysts, Inc., the global market for ventricular assist devices is estimated to be $1.2 Billion by 2014. NanoDynamics Life Sciences and the University of Pittsburg have evolved an infection resistant nanocoating for the drivelines of ventricular assist devices. The drivelines are the entry point components of these devices that make the transition from the outside to the in vivo environment of the patient, and are the most prone to the bacteria and fungi instigated growth of biofilms. This situation can dramatically restrict the benefits of antibiotics. The active ingredients of the NanoDynamics NDSilver coating are silver nanoparticles, which have large surface areas to effectively inhibit bacterial adhesion to the surfaces of indwelling medical devices, and to promote biocompatibility. Of all the metallic ions, silver has the most robust toxicity against microorganisms without negatively impacting healthy cells. The nanocoating also has the capacity for being dispersed uniformly within the coating to effectively


33


generate silver ions at appropriate concentrations to fend off the bacteria and the formation of biofilms. According to Ventracor there are an estimated 11.2 million sufferers of congestive heart failure worldwide, a total that is increasing by 10 per cent each year. Only about 3000 people receive a heart transplant each year. On-Q-SilverSoaker Catheter Coating According to the Centers for Disease Control and Prevention, more than 1.7 million patients in the U.S. alone are afflicted by nosocomial (hospital acquired) infections that result in ~90,000 fatalities annually. Of these infections, 32% involve the urinary tract, 22% involve surgical sites, 15% are lung-related, and 14% are bloodstream-related. The New York State Health Department, estimates that these infections reflect an additional, and in many cases avoidable, expenditure of over $4.5 billion. On a worldwide basis, approximately 5% to 10% of patients develop nosocomial infections during their hospital stay. A report from Global Industry Analysts estimates that the global market for autoimmune disease therapeutics will attain $49.8 billion by 2015. Therapeutics aimed at nosocomial infections will account for about 30% of this market, or ~$15.0 billion. I-Flow Corporation is employing nanoscale silver as an antimicrobial agent to potentially reduce infections for its ON-Q-Painbuster and ON-Q-SilverSoaker antimicrobial catheter combination. ON-Q-SilverSoaker is a Soaker catheter (used to deliver local anesthetic to surgical sites for post-operative pain reduction) that is treated with a nanosilver-based coating called SilvaGard. SilvaGard was developed by AcryMed, a maker of advanced infection control and wound care technologies. It is effective against a host of microorganisms and pathogens that can impact surgical sites, including penicillin resistant Staphylococcus aureus or “golden staph”, which typically causes staph infections. A 2007 multi-center colorectal study revealed that patients who received the ON-Q-Painbuster with the ON-QSilverSoaker had a significantly lower risk of developing surgical site infections and had shorter hospital stays. This innovation was supported by a study published in the Journal of Antimicrobial Chemotherapy, which confirmed the potential utility of nanosilver coated plastic catheters, and their role in the reduction of infectious events in patients with implanted catheters. A thin coating of sustained release silver nanoparticles was analyzed for its effects against the formation of biofilms and other pathogen-related catheter infections over a 90 day trial period. It was found that the nanocoated catheters showed considerable antimicrobial activity in vitro, and repressed the biofilm formation of Escherichia coli, Enterococcus, Staphylococcus and other strains of bacteria.


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These types of novel nanocoatings may have the potential for alleviating much suffering and saving many lives. From a business perspective, since October the 1st of 2008, Medicare decided that it would no longer compensate hospitals for the extra costs accumulated by patients who develop catheter or surgery-related infections. Hence, there are strong incentives to expeditiously move these types of advances forward. PLASM/PLASF Biomedical Device Coatings A company called Nanotherapeutics (Alachua, FL) has evolved a process called PLASM (Pulsed Laser Assisted Surface Modification) for applying fast drying and very thin coatings to the surfaces of biomedical devices. The company employs a technique whereby the surfaces of medical devices are modified via the deposition of ultra thin layers of polymers at near atmospheric pressure. According to the company website PLASM has utility for applying, “biocompatible coatings onto medical devices such as stents, catheters, vascular grafts, contact lenses, ocular implants, oral implants, hip implants, pacemakers/defibrillators, and bone fixation devices.” This coating technique involves the use of pulsed laser initiated vapor deposition, which allows for a high level of control over both the thickness and homogeny of the coatings. The process can also facilitate the incorporation of sustained release drugs; embedded within biocompatible and biodegradable polymers that can elute from the polymeric matrix over a number of days. The company has also developed an enhanced coating process called Pulsed Laser Assisted Surface Functionalization (PLASF), by which more specialized and complex surfaces might be synthesized (e.g., enzymes or active proteins tethered to a polymeric substrate). The PLASF process may enable unique surface attributes such as increased hydrophobic, hydrophilic, or adhesive capabilities. An additional attractive feature inherent to both coating processes is that medical devices of various sizes can be coated rapidly, within minutes. NanoCOAT, NanoFUSE and NanoDOX Additional nanocoating products in the pipeline for Nanotherapeutics include a coating process, which it calls NanoCOAT that can encapsulate nanoparticle or microparticle nuclei within thin coatings of biodegradable polymers or surfactants to, “slow the rate of release of an active component, improve the dispersion/flow properties, or increase the absorption into the systemic circulation.” This technique gives the ability for the dynamic release of encapsulated drugs, which may be controlled through the use of coatings compounds with specific degradation or permeability profiles.


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NanoFUSE is the first synthetic bioactive glass bone graft material that creates a direct bond with natural human bone materials when exposed to in vivo physiological fluids. It also had the capacity for controlling the formation of bone building osteoblasts, thus facilitating bone formation and the repair of damaged or injured sites. NanoDOX is a topical doxycycline monohydrate hydrogel for addressing “partial and full thickness diabetic, chronic cutaneous (dermal) ulcers”. The active ingredient is the antibiotic doxycycline, which is a molecule that lessens inflammation and encourages healing at the cellular level. The NanoDOX topical gel is applied directly to completely coat a wound, which is then covered by gauze dressing to afford a moist, optimal wound healing milieu. Antibacterial Surface Nanocoatings An anti-infective nanocoating called SilvaGard has been developed by AcryMed, Inc., (Beaverton, OR) that offers protection against infection arising from implanted medical devices. The company uses a proprietary technique whereby nanoparticles of silver, ranging in size from 2 to 20 nm, are created on the surfaces of implantable devices to prevent the formation of infective biofilms. This nanoscale coating can be tailored to be active for various durations; from weeks to many months. There are no undercoat layers required as silver nanoparticles adhere strongly and uniformly to the substrate. Researchers at the University of Kiel, (Kiel, Germany) have come up with a new strategy for the fabrication of antibacterial metal/polymer nanocomposite coatings whereby silver and gold nanoparticles are incorporated within only a thin surface layer, to impart greatly enhanced antibacterial efficacy. Dr. Vladimir Zaporojtchenko and co-workers have developed a new co-deposition sputtering method to protect surfaces against bacterial growth by depositing a thin composite layer comprised of silver nanoparticles in a fluoropolymer matrix. Interestingly, the antibacterial effect of the silver was greatly enhanced by then depositing an additional very thin layer of gold clusters. The much more effective release of silver ions is attributed to the combination of consumable silver nanoparticles with the gold clusters, which are not consumed. In many other antibacterial nanocoatings the silver nanoparticles are embedded and encased, for the most part, within the carrier matrix and are not therefore available at the surface where they can freely release silver ions. This co-sputtering technique can potentially synthesize composite nanocoatings with controllable thicknesses that draw from a large selection of metal fillings.


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Bioactive Implant Nanocoatings It has been discovered that when biologically active nanopatterned coatings are added to implant surfaces, they can enhance biocompatibility. Researchers at the Radboud University Nijmegen Medical Center, (Nijmegen, Netherlands) have proposed a straightforward and cost-effective alternative to conventional biomedical coatings for bone implants. A simple single step process utilizes the enzyme alkaline phosphatase (ALD) to create a unique biomedical coating that stimulates biomineralization at the implant/bone interface. Thus a relatively rapid and secure fixation of bone implants might be realized with beneficial clinical outcomes. The research team employed an electrospraying method to apply a uniform bioactive coating onto titanium implant surfaces. They are also exploring the feasibility of organic/inorganic composite coatings for improve bone response. The premise behind a composite approach is that a solitary class of materials does not come close to replicating the inherently highly complex structure of human tissues. It follows that more diverse hybrid surfaces will be required to properly mesh with these biomaterials. Nanoemulsive Burn Treatment Scientists at the University of Michigan (Dearborn, MI) and NanoBio Corporation have formulated a nanoemulsive lotion that dramatically inhibits the growth of bacteria and inflammation in second degree burn victims and has the capacity for more deeply permeating the skin to kill subdermal bacteria than do current creams for burn treatment. The nanoemulsion, which has also been shown to be effective against fungi and bacteria, is comprised of soybean oil, alcohol, water and detergents that are emulsified, giving constituents that are 400 nm in diameter. When applied to partial thickness (second degree) burns this formulation acts to decrease the activity of two inflammatory agents (cytokines) that are instrumental in cell signaling events. Thus, early burn damage might not progress as quickly, thereby diminishing skin graft requirements. Nanomatrix Stent Coating University of Alabama at Birmingham (Birmingham, AL) researcher Dr. Ho-Wook Jun and coworkers have created a synthetic nanomatrix stent coating that mimics natural endothelium; the thin layer of cells that comprises the inner lining of blood vessels. This discovery has prospects for the prevention of post operative scarring along blood vessel walls, thus significantly decreasing the risk of future thrombosis events or the formation of obstructions at the stent site. This biomimetic stent coating could be applied to drug eluting stents, which are currently being implanted


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at a rate of 1 million per year worldwide. According to a report by Research Facts, “the global stent market has an estimated value of US $6.4 billion, of which 37% is generated in the United States.” This innovative coating might enable blood vessels to recover completely, in contrast to existing stents. Beyond its use in stents this nanocoating might also be a practical solution for a range of cardiovascular devices encompassing vascular grafts and prosthetic heart valves. Polyzene-F Nanocoated Cardiac Stents A study was presented at the 20th International Symposium on Endovascular Therapy to describe a cobalt chromium stent nanocoated in poly[bis(trifluroexthoxy) phospazene] or Polyzene-F. This nanocoating has the potential for opening and healing blocked heart arteries, while eliminating the sometimes life-threatening risks associated with drug eluting stents. Polyzene-F is a product of CeloNova Biosciences, Inc., (Newman, GA), which allows a diverse range of applications on a multitude of substrates including polymers, metals, and ceramics. The nanocoating, with thicknesses that range from less than 50 nm to 150 or 200 nm, can be applied by a variety of methods that are tailored to optimize its performance for a given application, while retaining its beneficial properties. Additional advantages that are promoted for this nanocoating include its biocompatibility, anti-inflammatory attributes, and the promotion of endothelial cell growth. It negates inflammatory cell reactions and the surface acts to impede the adhesion of platelets that can lead to blood coagulation and thrombosis. Alternate nanocoatings for stents that are being investigated by other researchers include amorphous hydrogenated carbon and titanium nitride, which have unique properties such as great hardness, chemical stability, and superior resistance against wear. Two of the primary objectives for stent nanocoatings are the effective interference of the adsorption of proteins and the disruption of cellular adhesion processes. Biliary Stent Clogging Solved by Nanotechnology Plastic stents that are utilized for biliary (bile ducts) drainage tend to clog with an accumulation of “sludge” comprised of proteins, glycoproteins, or bacteria that adhere to the stent. The bile flow is not swift enough to clean the surface. An effort was undertaken to optimize the biliary stent surface such that it would easily release any potential accumulating detritus. Researchers at the University Medical Center Eppendorf, (Hamburg, Germany) modified plastic biliary stents with two types of organic/inorganic sol-gel coatings


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and incubated them for 35 days with sterilized human bile and Escherichia coli. The coating candidates included Teflon coated with hydrophobic Clearcoat, and Teflon with a sol-gel coating synthesized of organic epoxides and propylaminosilane. Scanning electron microscopy was employed to determine the amount of sludge that had accumulated on the surfaces of the samples. It was revealed that the sludge accumulation was reduced on the stents that were coated with the custom sol-gel coated Teflon in comparison to the Teflon with Clearcoat. Hence it seems plausible that biliary stent clogging might prevented through the use of sol-gel nanocoatings. Antimicrobial Barrier Dressings The company NUCRYST Pharmaceuticals (Princeton, NJ) has introduced a medical nanocoating platform called SILCRYST, which is incorporated into Smith & Nephew's (London, UK) Acticoat antimicrobial barrier dressings. Nanocrystalline silver is deposited on substrates like high-density polyethylene to produce nonadherent wound care dressings, using a process called magnetron sputtering (a type of physical vapor deposition). Pure bulk silver is bombarded with positive ions with in a vacuum chamber, which releases individual silver atoms that are then activated by plasma (partially ionized gas that contains free electrons). The silver atoms are then reformed on a substrate as highly energized nanocrystalline structures. Bulk silver is composed of microcrystals (1-2 µm), which are slow to dissolve, thus making limited amounts of silver ions available. When the silver is reduced to nanocrystal size (~1-100 nm) it exists in a much higher energy state with a far greater surface area, giving a increased level of dissolution with which to enable antimicrobial properties. The SILCRYST nanocrystals adsorbed to the Acticoat medical dressings rapidly deliver the sustained release of antimicrobial silver ions for up to 7 days, which translates to fewer dressing changes and less pain for burn patients. This silver-based nanocoating is highly toxic to, and acts as a barrier against 150 potential wound pathogens. The first topical antimicrobial gel to incorporate ionic silver is called SilvaSorb, which was developed by AcryMed, Inc., (Beaverton, OR). The gel can be applied directly to burns, scrapes, and other wounds to provide protection from infection brought on by Methicillin-resistant Staphylococcus aureus as well as a range of antibiotic-resistant organisms. SilvaSorb has been integrated into a number of other AcryMed products as well, including its MicroLattice wound dressings that regulate moisture at the wound site to optimize the local healing environment in conjunction with supplying broad spectrum antimicrobial protection over a seven day period. Two other SilvaSorb-based products having seven day effectiveness timelines are a wound cavity dressing to disinfect and control heavy drainage, and dressings that are specifically designed to keep the insertion sites of indwelling medical components free from infection


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Nanofilms for Scar Free Surgery At Waseda University (Tokyo, Japan) Dr. Shinji Takeoka has developed biodegradable free standing 20 nm thick nanofilms for biomedical applications that may one day replace surgical stitches. The nanofilms were comprised of poly-Llactide (PLLA) (a biocompatible/biodegradable thermoplastic derived from corn starch or sugar cane) and fabricated using a spin coating and peeling process that employed polyvinyl alcohol (PVA) as a foundation film. This ultra thin film has superior sealing utility for gastric incisions and as an efficient adhesive free wound dressing. It serves as an advantageous candidate for the replacement of many conventional suture or ligation procedures as it is minimally invasive and simple to apply, which can translate to considerable time savings. This nanofilm would be an important boon for the plastic surgery sector as it will apparently leave no scar tissue behind. In instances of severe trauma involving internal organs and tissues, suturing can be arduous, and having sometimes questionable results. Another issue is that post operative internal scarring can manifest into unsafe tissue adhesions whereby sites that are supposed to be separate under normal conditions are fused by scar tissue. The nanofilms have a high binding affinity to tissues despite being free of any adhesives. This action could be seen as analogous to the application of gold leaf to a surface as it is so thin that it will immediately gravitate toward a surface to which it is being applied. Dissolving stitches made of PLLA are commercially available. However, no one to date has configured this material as ultra thin sheets. Although human clinical trials with this nanomaterial may still be several years away, additional applications are envisaged for these nanofilms that include endoscopic surgery, regenerative medicine, tissue engineering, and to assist with the healing of external burns and wounds. Nanocoatings for Hearing Aids Siemens Hearing Instruments (SHI) (Cambridge, ON, Canada) is marketing its Intuis BTE hearing aids that are treated with its anti-adhesive hydrophobic lacquer nano coatings to prevent the ingress of water, perspiration, and dirt into the devices, as well as to resist corrosion. According to the company description, this coating applied to the hearing aid housing at a high temperature serves to increase product reliability and lifetime. Another SHI device is called CENTRA Active, which incorporates its AquaProtect hydrophobic and oleophobic nanocoating. An additional feature of AquaProtect, in addition to its providing a water and oil repellant surface, is that it actively reduces capillary action, whereby liquids typically tend to fill small crevices or minute openings in a surface. It also resists dirt and debris and dissuades microbial growth.


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Starkey Laboratories (Eden Prairie, MN) has developed a potent water repellent nanocoating for its hearing aids that it calls Advanced HydraShield. Company president Jerry Ruzicka states that “you can literally throw the aid in a bucket of water, leave it there for hours, pull it out and it still works. We apply a nanocoating to the device that not only protects it against from water, but it also provides a unique corrosion resistance throughout the life of the device.” Nanocoating for Cochlear Implant The European Commission has funded the NanoEar Project, which will endeavor to “develop novel multifunctional nanoparticles (MFNPs), which are targetable to selected cell populations, biodegradable, traceable in-vivo, and equipped with controlled drug release. With over 44 million EU citizens with hearing loss and 40 000 profoundly deaf who could immediately benefit from a MFNP-based novel drug carrier system and drug coated cochlear implant, the inner ear is a unique target.” One of the aims of the consortium is to test biodegradable biomaterials such as poly(lactic-co-glycolic acid) (PLGA), Poly(ε-caprolactone) (PCL), chitosan, and silica for their drug payload and release capacities when embedded within cochlear implant electrode coatings. On of the stated milestones will be to “produce a novel human cochlear implant promoting improved cochlear nerve-implant integration. In this novel demonstration the implant will include a MFNP drug reservoir providing continuous drug delivery and MFNP electrode coating providing targets for nerve growth.” The group is exploring a variety of nanocoating methods that will facilitate the surface attachment of different ligands, signaling molecules and markers. Nanocoating for Dermal Patch MIT (Cambridge, MA) researcher Xingfang Su and coworkers assembled a layer-bylayer lamination of protein and CpG oligonucleotide (a type of single stranded DNA) loaded films that integrating a hydrolytically degradable polymer for potential use in a transcutaneous (dermal patch) drug and vaccine delivery device. The nanofilms were constructed via electrostatic interactions and loaded with an analog drug; dried ovalbumin protein (ova), the main protein in egg white, and single stranded DNA. When rehydrated in a saline solution, the ova was released in a form that was not degraded and the proteins did not aggregate. Thus, the structure of the biomolecules remained intact during release. By employing confocal fluorescence microscopy and the ear skin of a mouse model it was shown that there was a rapid transfer of the ova from the nanolayered coating into the disrupted skin and uptake of the protein into skin resident cells. The CgP,


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however was release in a more stable and sustained manner. When adhered to the skin as dermal patches, the nanocoating delivered both the ova and the CgP to Langerhans skin cells, whose typical function is to take up and process microbial antigens. This technique and process may serve as a novel method for the efficient storage and delivery of drugs or vaccines across the skin barrier. Analyte Biosensor for Detection of Drug Abuse Researchers at the University of Vigo (Vigo, Galicia, Spain) have developed nanoparticles that are coated with antibodies to identify bioanalytes associated with drug abuse. They attached antibodies that have an affinity for a key cocaine metabolite called benzoylecgonine (which is generated in the liver) to the surfaces of silver nanoparticles that were adhered to carbon nanotube substrates. When a solution containing the metabolite was mixed with and bound to the antibodies their structure was altered. The researchers then employed Raman Surface Enhanced Spectroscopy to establish the exact structural changes and hence could determine the overall concentration of the metabolites. This technique may be carried out using urine or saliva to effectively reveal the existence and concentration of the drug and the system can be modified to disease related molecules. Carbon Nanotube Coatings for Bone Tissue Engineering A nanocoated foam that may have utility as a scaffold for bone tissue engineering was investigated by Ewelina Zawadzak (Warsaw University of Technology, Warsaw, Poland) and associates. Carbon nanotubes were coated onto a polyurethane foam surface using electrophoresis; a coating method whereby charged colloidal particles migrate in solution via a submerged electrode to a substrate under an applied electric field. A simulated body fluid was used for in vitro trials to elucidate the effect of the presence of the carbon nanotube coating on the surface bioactivity of the polyurethane (PUR) based scaffold. This was determined by the accumulation of calcium phosphate (CaP) compounds (hydroxyapatite) on the foam substrates. The results showed that the nanotubes hastened the build up of the CaP on the foam due to the much higher prevalence of available nucleation sites to spur the growth of the crystal in contrast to the controls. The researchers concluded that the PUR foam enhanced with the coating of carbon nanotubes has the potential for serving as effective bioactive scaffolds for the generation of engineered bone tissues.


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FILMskin Project An innovative pliable multifunctional synthetic skin for prosthetic hands and arms is under development at the Oak Ridge National Laboratory (ORNL) in conjunction with the National Aeronautics and Space Administration (NASA). This artificial skin technology could incorporate sophisticated nanosensors into its matrix; enabling its wearers to potentially feel heat, cold, and touch. Researchers involved with the FILMskin project at the ORNL Nanomaterials Synthesis and Properties Group and NASA’s National Institute of Aerospace hope to develop a multifunctional material that will closely resemble the thermal attributes of real human skin, which will then be interfaced with advanced nanoscale temperature and pressure sensors. The high thermal conductivity of carbon nanotubes may facilitate the creation of a nanocomposite that can emulate the nuances of heat distribution that exists between muscle, fat and skin. It was learned that a polymeric composite could be made that allows for higher heat conductivities than those in different human tissues. The initial aim is to fabricate a small section of the thermally conductive synthetic skin and then to integrate vertically aligned carbon nanotubes to quickly transmit heat to temperature sensors. Heat was shown to conduct through the nanotube infused polymer at a rate that was 20 times faster than through the neat polymer. This will facilitate rapid response times from the surface of the synthetic skin to the temperature sensors. The next stage will include the design of nanosensors that can distinguish between temperature and pressure variations. Cubosome Artificial Vernix An advanced therapeutic nanomedical dermal coating for premature infants that are born without a completely formed outer skin layer is being investigated by researchers with Proctor & Gamble and the University of Cincinnati (Cincinnati, OH). Cubosomes are oil and water based nanocrystalline particles (~50-200 nm), which because of their novel morphology, exhibit nanoporosity when they selfassemble. Because of the way they interact with each other and with neighboring water and oil molecules, they can cumulatively form a “breathing layer” for skin at the nanoscale. In contrast to the protective coating that is formed by Vaseline, cubosomes have the ability to not only protect the skin from external elements, but can permit respiration and moisture exchange with the environment. Titania Nanotube Drug-Eluting Coatings University of California, San Francisco, (San Francisco, CA) investigators have developed nanocoatings comprised of titania nanotubes that may have potential for


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the elution of drugs from the surfaces of implanted biomedical devices. They fabricated well aligned titania nanotube arrays via anodization and could precisely control their diameters and lengths while preserving their mechanical properties. The nanotube coatings can be deposited on any three dimensional surface, making them readily amenable for application to biomedical implant surfaces. The diameters of the nanotubes, their wall thicknesses and lengths can be modified simply to conform to specifications of the particular drug molecules that are intended for encapsulation and delivery. It has been demonstrated that there is a good degree of dimensional flexibility for these nanotube arrays, as the pore diameters can be varied from 12 nm to 180 nm, the thickness of the walls from 5 nm to 34 nm, and lengths from 200 nm to 360 mm. Thus, the drug release kinetics can be finely regulated by appropriately configuring the dimensions of the nanotubes. Their surfaces are very hydrophilic, but can be tuned with the addition of organic molecules. Features like these make the titania nanotube arrays very attractive as drug eluting coatings, not only for the surfaces of orthopedic implants, but for dental implants and stents as well. Carbon Nanotube Coated Brain Probe Electrodes Considerable improvements might be seen in the sensitivity of brain function probes by coating metal neural electrodes with carbon nanotubes. This capacity may enable a deeper understanding of brain diseases such as Parkinson’s and epilepsy, which arise from electrical impulse aberrations in the brain. The electrodes that are currently in use for the acquisition of neural activity data are restricted by their inherent electrical impedance, which impairs their capacity for the generation of highly accurate readouts. Impedance also limits their usefulness when they are used for the in vitro simulation of brain activity, where the efficient conveyance of voltage for the stimulation of neurons is required. The excellent electrical properties of carbon nanotubes have the potential for radically improving the performance of implanted electrodes by increasing their sensitivity and hence, the probe/brain cell interface. It was estimated by Edward Keefer at the University of Texas Southwestern Medical School and fellow researchers that when the probes were coated with carbon nanotubes their efficiency could be increased by over a thousand times. The researchers assessed two commercially available electrodes made of tungsten and stainless steel wire with two animal models; within the motor cortex of rats under anesthesia, and within the visual cortex of conscious rhesus macaque monkeys. Using nanotube coated and uncoated probes they discovered that in both instances the carbon nanotube coated probes generated far better measurements,


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and when the nanotubes were embedded within a conductive polymer coating, their performance was further improved. A scanning electron microscope revealed that the nanocoating was not compromised by the monkey’s robust outer brain layer, known as the dura mater. Although the probes fared well in the animal models they are not yet ready for human use. This is because additional studies are required to learn how the probes will hold up over lengthy exposures to human neural tissue. Other benefits of these nanocoated probes include their biocompatibility, potential use as dynamic substrates for the growth of neurons, and their seamless integration into existing brain/machine devices. Nanobiomaterial Coating for Brain Implant Electrodes There are a range of brain implants that are currently in use, which include brain pacemakers toward the alleviation of epilepsy symptoms, Parkinson’s disease, and depression, and retinal implants (e.g., arrays of electrodes that are implanted behind the retina). One critical challenge is that the surfaces of these electrodes, which serve as the neural interfaces for implants with expected functional lifetimes of from hours to years, are still quite rudimentary. As are their compatibility with complex brain tissues and capacity for the intimate interaction with neurons and other species of brain cells. University of Michigan (Dearborn, MI) researcher Mohammad Reza Abidian has devised a strategy for the fabrication of multifunctional nanobiomaterials that can be utilized for the coating microelectrode arrays toward improving their biocompatibility, performance, and for the potential release of drugs. The nanocoating is comprised of three complimentary elements that work cooperatively to allow the electrodes to interface more seamlessly with the brain. The nanobiomaterial coating consists of an electrically conductive polymer (poly(3,4ethylenedioxythiophene) (PEDOT)), a natural gel-like buffer (alginate hydrogel) that is partially derived from algae, and biodegradable nanofibers that are loaded with a controlled release anti-inflammatory drug (dixamethasone). The biodegradable nanofibers are fabricated via electrospinning, during which the dixamethasone is incorporated. They are then encapsulated within the polymer hydrogel matrix. It was found that the electrical properties of the resulting neural microelectrodes were significantly improved with these nanocoatings. The PEDOT polymer worked to enhance the electrode/neuron interaction due to a diminished electrical resistance. The hydrogel component of the electrodes has mechanical properties that are more amenable to being interfaced with brain tissues than their conventional counterparts. Hence, the nanocoated electrodes are less likely to cause damage. It also provides a scaffold through which the conductive polymer can


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permeate and establish itself. A reconfigured version of the electrodes incorporates PEDOT nanotubes and further enhances the signal to noise ratio by about 30% over the uncoated electrodes. The drug loaded nanofibers function to prevent the encapsulation of the electrodes, which occurs when the immune system signals the body to envelop foreign materials. The nanofibers can negate this response effectively as they work with the diffusion barrier that is formed by the alginate hydrogel matrix to release the anti-inflammatory drugs on a controlled and sustainable way as function of their biodegradation. Immune system mediated brain electrode encapsulation is one the primary causes of degradation and loss of function as the communication between the electrode and neurons is thus effectively stopped. Nanocoating for Surgical Blades Advanced fabrication techniques have allowed for improvements in the manufacture of surgical blades, resulting in cutting edge diameters of from 5 nm to 1 μm. Surgical blades that are utilized in ophthalmology are machined from crystalline or polycrystalline silicon wafers and can have cutting edge radii of from 5-500 nm, with a similar quality as a diamond cutting edge. However, stability can be an issue as the blades can flex under pressure, which may lead to potential tissue damage. Nanostructured carbon coatings have been deposited on trephines (cylindrical blades for the removal of tissue such as that of the cornea) that resulted in the formation of cutting edges with enhanced stability with diamond-like attributes. It was found in efficacy studies with pig cornea that the nanocarbon coated blade had improved cut surfaces that untreated edges due to a lower coefficient of friction. An added advantage is that the coated blades demonstrated a biologically inert surface, which acted to decrease the physical adhesion to tissues. The nanocoating, which may be composed of any material that is harder than silicon can be deposited by chemical vapor deposition and can range in thickness from 10 nm to 2 μm. Deposited materials may include silicon nitride, titanium nitride, titanium carbide, aluminum titanium nitride, silicon dioxide, silicon carbide, boron nitride, and diamond-like nanocrystals. Surgical blades made of carbide have been coated with diamond to thicknesses of from 5 μm to 25 μm by GFD Gmbh, (Ulm, Germany). A plasma process is then employed to sharpen the blades giving a surface roughness of from 20 - 40 nm and a durability that is 10 times that of normal blades.


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Nanocoated Ibuprofen Tablets An increase in production and a reduction in downtimes have been achieved through the use of a nanocoating by chemical company BASF for the manufacture of its Ibuprofen DC 85 (analgesic and anti-inflammatory) tablets. By applying a nanocoating to the Ibuprofen crystals, high speed tablet presses can produce up to 700,000 tablets per hour in contrast to the typical 200,000 tablets per hour. As the melting point of the Ibuprofen it quite low, it has a tendency to stick to the surfaces of the tablet punches, which leads to multiple downtimes for their cleaning. Thus the nanocoating reduces production and labor costs; savings that can be transferred to the consumer. The exact nature of the nanocoating is not revealed, however it does function as a shield against the heat that is generated by the tablet presses. Other advantages imparted by the nanocoating are that smaller tablets can be manufactured because the volume of lubricants that are commonly included in the formulation can be decreased, and it helps to dissolve the tablets more quickly once ingested permitting the drug to take effect much more rapidly.

NANOCOATING SYNTHESIS TECHNIQUES There are a variety of techniques that have been developed to fabricate nanocoatings that have unique nanostructures with diverse functionality. In some cases the specific geometries if the nanocoatings facilitate or enable its functionality. For instance, nanocoatings can be made to exhibit superhydrophobicity if they are constructed such as to present micron scale bumps combined with nanoscale bumps on their surfaces. This composite geometry is what enables the superhydrophobic “Lotus Effect” on natural lotus (Nelumbo) leaves. Below are described a number of methods by which nanocoatings are synthesized. Subsequently, Table 11 briefly surveys the traditional types of coatings that are utilized in industry, whereas Table 12 describes the types of materials used in composite nanocoatings and nanoadhesives, and Table 13 lists some of nanomaterials that are integrated into nanocoatings. Chemical Vapor Deposition (CVD) Chemical Vapor Deposition (CVD) is a commonly utilized technique for depositing an extensive array of nanocoatings onto diverse substrates. In operation, room temperature mixtures of gases are introduced into a reaction chamber, which is typically under some degree of vacuum. When the reactant gases come into close proximity to the deposition surface they are heated, and contingent on the operating parameters these gases undergo chemical reactions while in the vapor state prior to adhering to the deposition surface. There are many configurations of CVD and Table 10 lists some the primary methods in use today. Copyright© BCC Research, Wellesley, MA USA, Web: www.bccresearch.com/

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TABLE 10 TYPES OF CHEMICAL VAPOR DEPOSITION (CVD) Type Atmospheric Pressure CVD (APCVD)

Temperature/ Pressure Range 150-550°C/ ~1 atm

Atomic Layer CVD (ALCVD) (aka Atomic Layer Epitaxy and Atomic Layer Deposition)

275–400°C/ ~1 atm

Hot-Wall Thermal CVD

800-2000°C/ 1 atm to several mTorr 700-1000°C (substrate) 2000-2300°C (filament)/ 10-100 Torr

Hot Wire CVD (HWCVD) (aka Hot Filament CVD (HFCVD) or Thermocatalytic Decomposition) Hybrid Physical CVD (HPCVD) Plasma Assisted CVD (PACVD)/ Plasma Enhanced CVD (PECVD) RF Plasma Assisted CVD (RFPACVD)

600-5000°C/ 100 mTorr-500 Torr 800-1000°C/ 1-30 Torr

DC Plasma Assisted CVD (DCPACVD)

600-800°C/ 200 Torr

Aerosol Assisted CVD (AACVD)

650-815°C/ 3.2 Torr

Direct Liquid Injection CVD

530-925°C/ 1atm-18 Torr

Low-Pressure CVD (LPCVD)

100-1300 °C/ 20 Torr

Metal-Organic CVD (MOCVD)

200-450 °C/ 2 Torr 700-1000°C/ 5-100 Torr

Microwave Plasma-Assisted CVD (MPCVD)

Process Description Deposition of coatings possible at atmospheric pressures. Inferior coating quality in comparison to other CVD methods. Two complementary precursors are alternatively introduced into reaction chamber. Allows extremely precise control of film thickness and uniformity. Batch operation in hot wall or cold wall reactors. Feedstock gases are very efficiently decomposed into atomic radicals at the surface of a hot filament (typically tungsten or tantalum) high substrate deposition rate. Can be enhanced with electron bombardment. Precursor gas is decomposed in conjunction with the vaporization of a solid element. Utilizes plasmas to enhance precursor reaction rates. Couples RF power to the plasma gas to produce diamond coatings with small crystal grains and good adhesion. A DC voltage is discharged between an opposing cathode and anode in a reaction chamber, whereby an introduced reaction gas decomposes and is deposited on a substrate that is mounted on the anode. Precursors transported to substrates by an ultrasonically generated sub-micrometersized liquid/gas aerosol droplets Provides accurate, stable delivery and control of precursor. Multiple precursor compounds can combined into a single solution including solids and other compounds not suitable for vapor delivery. Operates at sub-atmospheric pressures and thus reduces undesired gas phase reactions for improved uniformity of coating. Utilizes metal-organic precursors such as alkyls and hydrides. Electrodeless process that avoids electrode erosion contamination, and produces higher plasma concentrations.


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Rapid Thermal CVD (RTCVD)

400-1300 °C/

Remote plasma-enhanced CVD (RPECVD)

650°-850°C/ 10-1000 mTorr

Ultra-High Vacuum CVD (UHVCVD)

500°-900°C/ 10-3-10-8 Torr

Molecular Beam Epitaxy (MBE) Chemical Beam Epitaxy (CBE) Polysilicon Deposition

TEOS Deposition

580 to 650°C/ 0.2-1.0 Torr 650-750°C/ 200-760 Torr

Arc Bond Sputtering (ABS)

High Power Impulse Magnetron Sputtering (HIPIMS)

1-10 mTorr

Superlattice Coating Deposition (SCD)

260 °C/ 8-10-6 Torr

Uses heating lamps or other means to rapidly heat the wafer substrate to reduce undesired gas phase reactions. Comparable to PECVD but wafer substrate is positioned away from the plasma region to allow room temperature processing. Amenable for batch processing with exceptional control of doping and thickness with very background low oxygen and carbon concentrations.

Deposition of polycrystalline silicon on semiconductor wafers at a growth rate of 10-20 nm/min. Uniformity of thickness is at +/- 5%. Low pressure pyrolytic decomposition of tetraethoxysilane (TEOS) for deposition of high quality economical SiO coatings on silicon wafers. Combines Arc Evaporation (highly ionized metal plasma) and Unbalanced Magnetron Sputtering (high deposition rate and macro defects-free structure) to produce a large variety of metal and ceramic coatings 3 - 4 nm in thickness. The multi-target arrangement allows production of nanoscale multilayer coatings or multicomponent coatings at high production output. Utilizes extremely high power density pulsed magnetron discharge, which is distributed over the target area. Applied to nitride coating deposition and the pretreatment of substrates to enhance adhesion. Nanoscale multilayer structured coating is deposited by unbalanced magnetron sputtering. The interfaces between the individual layers in the superlattice coating act as barriers to prevent atomic dislocation across the layers, which results in a superhard material. Layers are ~3nm thick and thousands of layers may be applied.

Source: BCC, Inc.


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Pulsed Laser Deposition Pulsed laser deposition (PLD) is a flexible and powerful technique for the synthesis of nanostructures such as oxide thin films, giving good control of grain size, coating density, and surface smoothness. These are essential characteristics for thin film coatings; in particular for those that are superconducting or ferroelectric. The PLD process involves directing intense laser pulses through the optical window of an ultra high vacuum chamber to strike the surface of an internal solid or liquid target. Above a certain power threshold the target material is vaporized to produce a highly energetic plume that is directed at a substrate where the material undergoes recomposition to form a thin film coating. A reactive gas may also be introduced so as to enhance the growth process. The plume may be a composite of macroparticulates, molecules, atoms, or ions. Layer by Layer Self-Assembly Layer by Layer (LbL) self-assembly techniques are increasingly being utilized because of their capacity for the synthesis of nanometrically precise and complex multifunctional films/coatings on surfaces. This is made possible through the sequential adsorption of polycations, polyanions, or nanoparticles, which allows for an intimate control over their composition and properties. Most LbL coatings consist of polyelectrolytes that electrostatically self-assemble into layers. They can, however, also be synthesized via the hydrogen bonding of polymers and inorganic nanoparticles to achieve enhanced control over mechanical, chemical, thermal, electrical, optical, and magnetic attributes. Hierarchical constructs can be realized that display novel characteristics, which are not present in the constituent building materials. LbL can be carried out on a myriad of substrates such as noble metals such as gold and platinum, oxides, including mica and quartz, or synthetic polymers like poly(methyl 2methylpropenoate) (PMMA) or polyethylene terephthalate (PET). A number of polymers such as polytetrafluoroethylene (PTFE) and polyethylene (PE) are difficult to coat; necessitating the use of a primer. Adhesive mussel proteins are rich in catechol and amine functional groups that promote adhesion to almost any type of organic or inorganic substrate. Synthetic analogs of these proteins, such as low molecular weight dopamine, form sticky polymeric coatings on a wide array of surfaces at alkaline pH. Thus it may be possible to formulate adherent synthetic primer coatings to further enhance LbL capabilities. These versatile multilayered nanocoatings are not restricted to planar surfaces but can also be applied to colloidal substrates, nano/microparticles, and hollow cavities. Thus an extensive range of applications can be envisaged.


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Langmuir-Blodgett Nanoarchitectures The Langmuir-Blodgett technique is well recognized for the spontaneous assembly of single-dimensional monolayered nanometric building blocks that are comprised of organic molecules. This process can be used to construct multilayered nanocoatings (each several nanometers thick) of amphiphilic (both hydrophilic and lipophilic) molecules via the transference of monolayers from a water surface to a solid substrate in a layer by layer manner. A variety of potential geometries may be possible, as the synthesis process is driven by interactions between different layers and constituents thereof under varied surface pressures. This method is appropriate primarily for water soluble charged particles including polyelectrolytes, proteins, DNA, viruses, sugars, colloidal particles, dyes, and molecular assemblies such as bolaamphiphile monolayers and lipid bilayers. The polyelectrolytes typically used in this nanocoating assembly method are: (Polycations)

 Polycyclic aromatic hydrocarbon (PAH)  Poly(diallyl dimethylammonium) chloride (PDDA)  Polyethylenimine (PEI) (Polyanions)

 Poly(styrene sulfonate) (PSS)  PANi–poly(vinylsulfonate) (PVS) An alternating layer by layer architecture is typically based on electrostatic interactions, although stereo-complexation, charge-transfer, and biospecific assembly strategies might also be employed. The relatively straightforward technique for building up nanoscale coatings on a substrate involves the immersing of a solid support with a charged surface in a solution containing an oppositely charged polyelectrolyte. After the support is rinsed in pure water it is immersed again in a solution of oppositely charged solution. This process is repeated until the desired number of monolayers is reached. The adsorption amount can be determined by ultraviolet-visible or fourier transform infrared spectroscopy, and the layer thicknesses can be elucidated via Xray reflectometry, surface plasmon resonance, or scanning angle reflectometry. In order to create quality multilayered assemblies, drying is not recommended between each layer absorption step. This will act to increase the thickness of adsorbed layers due to an increase in surface coarseness. The assembly of UV reactive polyelectrolytes can be utilized to construct micropatterned thin film coatings. Multilayers of diazo resin (a photosensitive Copyright© BCC Research, Wellesley, MA USA, Web: www.bccresearch.com/

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polymer that degrades easily under exposure to UV light) and poly(acrylic acid) (PAA) can be assembled by electrostatic attractive adsorption. When the completed assembly is irradiated by UV light the two components undergo covalent bonding via the formation of esters. When the assembled film is irradiated by UV light through a patterned mask, micron scale patterns with defined thicknesses can be created. A surfactant solution can then be employed to dissolve any non-irradiated portions of the film, but it will not affect the irradiated covalently bonded portion. Ultrasonic Nanocoating Sonotek Corp. (Milton, NY) is offering its precision ultrasonic nanocoating systems for the deposition of uniform nanolayers from solution feedstock onto a wide range of industrial, commercial, and other specialty/functional glasses. The company claims that savings of up to 80% in coating materials might be realized and that the ultrasonic atomizing nozzles used in the system will not clog. The droplet sizes can be correlated to different ultrasonic frequencies and can range from 18 to 49 microns, and the system is amenable to nanosuspensions typically employed for glass coating to impart properties such as low emission, anti-glare, anti-reflection, photoresist, superhydrophobic self-cleaning, touch screen (carbon nanotubes), solar cell compounds, as well as additional passive and active coatings. The ultrasonic nozzles ensure that the aqueous nanoparticle feedstock does not aggregate during the nanocoating procedure. This is of particular importance when coating with carbon nanotubes and other colloidal suspension that tend to agglomerate. Glancing Angle Deposition (GLAD) A proprietary nancoating technique called GLancing Angle Deposition (GLAD) has been developed by the Canadian company Micralyne, Inc., (Edmonton, AB, Canada) and the GLAD Laboratory at the University of Alberta, (Edmonton, AB) that is capable of depositing highly defined nanostructured coatings/films for a myriad of applications. This ultra-high vacuum deposition technique involves the precise control and orientation of the growth substrate at an oblique or glancing angle in relation to the vapor source. This nanostructured coating process operates under phenomena called atomic shadowing, whereby substrate nucleation sites can be induced to grow into exotic slanted, zigzag, helical, or other columnar geometries. In addition, the substrate rotate, which gives a resulting nanocoating that is not solid but rather appears (in one form under an electron microscope) as tightly-packed arrays of spiral noodles. The GLAD technique can accommodate a variety of organic and inorganic materials, thus multilayered composite nanostructures are possible. GLAD


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nanocoatings can impart added value to optical films, chemical and gas sensors, solar cells thermal barriers, catalysts, and polarization filters. TABLE 11 TYPES OF CONVENTIONAL INDUSTRIAL COATINGS Coating Type Corrosion resistant Ethylene-Chlorotrifluoro-Ethylene (ECTFE) (Halar) Epoxy Fluoropolymer Galvanizing High Velocity Oxy-Fuel (HVOF) Non-Stick Phenolic Plastic Powder Protective Rubber Elastomer

Thermal spray

Description Serves as barrier that prevents chemicals and other corrosive elements from contacting substrates. Protection against caustic chemicals and abrasion resistance. Thermosetting polymers that cure when mixed with a catalyst or hardener. Resistance to solvents, acids, and bases. Molten zinc coating for iron and steel to protect surfaces against corrosion. High velocity combusted gas technique employed to increase the hardness and bonding attributes of many coatings Polytetrafluoroethylene (PTFE) (Teflon) imparts anti-adhesive surfaces that are easy to clean. Thermoset plastic with low thermal expansion, high a resistance against abrasion and wear and friction. Applied to preheated parts, which are dipped into the molten plastic the post heated to create a uniform/smooth coating. Applied to parts via electrostatic or compressed air then cured to the melting point of the powder, which forms a smooth thin coating. Applied to isolate base materials from reacting with external gasses, liquids, or solids. For frequent but cushioned contact levels and holding friction. Molten powder is combusted or wire feedstock is applied by electric arc onto substrate.

Source: Engineers Edge


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TABLE 12 EXEMPLAR TYPES OF NANOCOMPOSITE COATINGS AND ADHESIVES

Nanocomposite

Enhancement

Surfmer-modified nanosilicate platelets into acrylic resins. Superparamagnetic metallic nanoparticles in monomers and/or a polymers. Epoxy resin modified with fumed silica nanoparticles. Nanocrystalline transitionmetal nitrides (e.g., titanium nitride (TiN), tungsten nitride (WN2), or vanadium nitride, (VN)), with amorphous silicon nitride (Si3N4) or boron nitride (BN). Gold and silver nanoparticles with polytetrafluorethylene (PTFE). Purely organic/hybrid organicinorganic polymeric matrices and anisotropic synthetic and natural clays. Iron oxide embedded silicon dioxide in adhesive polymer matrix. Source: BCC, Inc.

Enhances UV polymer curing technologies. Adhesive composition. Increases fracture toughness and inhibits crack propagation. Capacity for achieving coating hardness exceeding 40–50 GPa.

Enhanced antibacterial activity. Improved barrier properties, decreased permeability of oxygen and water, improved corrosion resistance and thermal stability. Magnetically toggled and reversible adhesive for metal and plastics.

TABLE 13 NANOCOATING ADDITIVES Nanomaterial Tin dioxide

Europium Oxide (Eu2O3)

Application Method/ Substrate Direct current (DC) electrodeposition method and thermal oxidation technique/ Titanium electrode Sol-gel method/Silicagermania photonic core

Enhancement Improved electrocatalytic characteristics by increasing adsorbed oxygen.

Emission intensity is improved.


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Silica nanoparticles Titanium dioxide nanoparticles Aluminium (III) oxide (Al2O3 )

Ultrasound initiated sol–gel reaction/Titania nanoparticles Hydrothermal process/Acidtreated multi-walled carbon nanotubes Polymeric precursor method in aqueous solution/Zirconia ceramic particles

Cellulose polymer

Cross-linked absorption via bifunctional compounds/ Macroporous silica

Silica nanoparticles

Water in oil microemulsion/Various nanoparticles Chemical absorption/ Semiconducting quantum dots

Poly(ethylene glycol) (PEG) polymer Biodegradable poly(ethylene glycol)poly(lactic acid)

Chemical absorption/ Semiconducting quantum dots

Self Assembled Monolayers (SAMs) (e.g. ,alkanethiols, silanes)

Self assembly/Various

Diamond and diamondlike carbon

Chemical vapor deposition, and other deposition methods/Various

Carbon nanotubes

Anodizing, electric current and heating/Titanium

Nanocrystalline metalloceramic

Ion beam assisted deposition/ cobalt-chromium-molybdenum alloy

Hydroxyapatite with zirconia nanocrystals

Ion beam sputtering or pulsed laser deposition/ceramics and metallic implant components Chemical adsorption/ metal, plastic, and ceramic Chemical vapor deposition/ Silicon, quartz, mica, and pyrolytic graphite

Conformal polyelectrolyte multilayers Single walled nanotubes (SWNT) Multi-walled nanotubes (MWNTs) Multi-walled nanofibers (MWNFs) Silver nanoparticles Gold nanoparticles Titania nanotubes

Chemical vapor deposition, codeposition sputtering/Various Anodization/Various implant

New nanocoating technique Enhanced photocatalytic activity Modifies sintering process, retards shrinkage temperature of pure zirconia. Show promise for the separation and purification of proteins via hydrophobic interaction chromatography. Imparts biocompatibility photochemical stability to nanoparticles Reduces/eliminates toxicity of quantum dots that are used for medical imaging. May permeate the blood brain barrier to allow drug delivery to brain and brain imaging. Improved corrosion and wear resistance. Enables highly sensitive biological and chemical sensing. Increased biocompatibility, wear properties and general longevity of medical implants. Monitor healing process and expedite bone growth for orthopedic implants. Prevents crack development and propagation for hip replacement surfaces. Promotes bone formation around an implant. Reduces wear for orthopedic implants. Allows fabrication of field emitters, sensors, and other electronic devices.

Potent antimicrobial properties. Drug eluting implanted


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Electrospun nanofibers in hydrogel matrix

materials Tungsten and stainless steel

devices. Prevents encapsulation of implanted brain electrodes and enhances the signal to noise ratio.

Source: BCC Inc.

CHARACTERIZATION OF NANOCOATINGS The multifaceted atomic level characterization of nanocoatings is, and will be critical for acquiring detailed information about their mechanical, chemical, electronic, biological attributes toward the synthesis of superior nanocoatings with very specific functionalities. X-ray Diffraction X-ray diffraction is a useful tool for the analysis of nanocoatings as it reveals lattice as well as crystal structures. When x-rays are directed at a crystalline material they are diffracted by the planes, atoms, or ions that reside within the crystal. Scanning Probe Microscopy Scanning probe microscopy (SPM) is a category of surface and interfacial characterization techniques that is utilized to investigate a material’s physical, chemical, or electrical properties at the nanometric and micro scales. This set of microscopy techniques employ a physical probe that scans a sample line by line in raster fashion. It enables the measurement of three dimensional surface topologies; the atomic resolution imaging of conductive and non-conductive materials; probing of various types of surface forces (e.g., friction, magnetic, electric); and the novel analysis of surface attributes (e.g., electrochemical reactions, hardness, elasticity, adhesion, charge density and energy, viscoelastic properties) as well as enabling potential surface manipulation and modification. Various SPM imaging modes encompass contact, non-contact, tapping mode, and scanning tunneling to allow for the highly adaptable nondestructive analysis of a wide range of material surfaces such as metals, ceramics, polymers, composites, biomolecules, semiconductors, ferroelectrics, and superconductors. The imaging of nanostructures involves the scanning of an exceedingly sharp tip within a very close distance of a sample to allow the specific probing of the surface for particular attributes via the specific interactions between the tip and the material surface. The resolution of the resulting images is contingent on the geometry and sharpness


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of the tip. Sharper tips scan a smaller segment of surface area to give an improved lateral topographic resolution. Scanning Tunneling Microscope (STM) The resolution for a scanning tunneling microscope is about 0.1nm in both the lateral (x,y axes) and vertical (z-axis) directions. To image a material the STM tip is brought to within 0.1 nm of a conductive surface and a voltage in the range of 0.1-1 volts is applied between the tip and the sample surface. At this close proximity the orbitals of the outermost electrons on the tip and those on the sample overlap. The applied voltage initiates a tunneling current whereby electrons from the STM tip tunnels into unoccupied energetic states of the sample. This technique is used to image the topography of the sample and can be run in either of two modes: 1) Constant Height Mode: The tip scans the surface at a constant height as the current is measured. The separation relationship of the tip to the sample provides data with which to produce a topographical image. 2) Constant Current Mode: The tip to sample separation is varied by utilizing a feedback loop to sustain a constant current. The position of the tip as it moves across the surface provides the data from which an image is formed. The STM allows sub-angstrom resolution but is confined to the imaging of conductive materials Atomic Force Microscope (AFM) The atomic force microscope is capable of imaging both conductive and nonconductive materials, at sub-nanometer resolution, in three dimensions. It utilizes a cantilever comprised of silicon nitride or monolithic silicon with a very sharp (2 nm radius) tip. Recently, single or double-walled carbon nanotubes have been employed to enhance AFM imaging by bonding them to the apex of the cantilever tip. The single-walled nanotube has a radius of 0.6 nm and the double-walled nanotube has a radius of 1.2 nm. The two most common AFM imaging techniques are: 1) Contact Mode: The tip moves along the sample surface and deviations in the force between the tip and sample are measured by monitoring the deflection of the cantilever when the tip is pushed against the surface of the sample. As scanning proceeds, the interactions between the tip and


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sample surface are recorded by reflecting a laser beam from the back surface of the cantilever into a sensitive photodiode detector. Any cantilever movements are quantified by variances in voltage outputs related to the changing positions of the laser beam on the photodetector. These movements are monitored in both horizontal and vertical directions and are translated electronically into topographic images. 2) Tapping Mode: The cantilever is induced to oscillate at its resonant frequency whereby the tip lightly taps the surface of the sample during scanning. This technique is favored when imaging soft and fragile samples such as biomolecules, polymers, and adhesives and removes the potentially damaging lateral shear forces that can take place during contact mode scannning. The tapping mode can also be employed for imaging other classes of materials such as silicon wafers, superconductors, metals, and insulators. Raman Spectroscopy Raman spectroscopy detects and processes the scattered radiation that is generated by molecules when they are illuminated with monochromatic laser light. This method identifies molecular species when a spectrometer collects and disperses this radiation onto a sensitive detector. Subsequent to the detector signal being processed, it is translated to a distinctive Raman spectrum. This technique may be employed for the investigation of solids, liquids, slurries, and gels.


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NANOCOATINGS IN THE CONSTRUCTION SECTOR Building materials are increasing in sophistication and are beginning to be imbued with novel and “smart” functions as are wall coverings, bathroom tiles, counter tops, and windows. Nanocoatings will contribute considerably to the enhancement of these items; making them more environmentally friendly, dynamic, and durable than standard materials. We may look forward to many nano-enabled innovations in the construction industry as competitors vie for the edge in the market. Table 14 reviews the global market for nanocoatings in this sector. Antimicrobial Wall Paint An emissions free antibacterial paint called Bioni Hygenic has been developed by researchers at the Fraunhafer Institute for Chemical Technology in collaboration with Bioni CS GmbH. This wall covering is infused with silver nanoparticles and is offered as a permanent alternative to biocide-based coatings. The silver nanoparticles in the paint prevent the formation of mould on building interiors and the growth of algae on exterior walls. Bacteria, germs, or fungal spores that come into contact with surfaces that are coated with the paint are rapidly eliminated. This is due to the action of silver ions that interfere with the cell metabolism of many types of microorganisms and thus remove opportunities for the microbes to develop resistance. Levels of hygiene are purportedly improved when these paints are applied to protect against mould and mildew in medical and other health facilities, food processing plants, and domestically in kitchens and bathrooms. Bacterial growth can easily be initiated and will propagate on the surfaces of walls and ceilings when contacted with microscopic aerosol droplets, dust deposition, when splashed by organic liquids, and via contact with human skin. The longevity of the adsorbed bacteria can range from days to years. Unlike biocidal paints, Bioni Hygenic does not emit substances into the air as the active silver nanoparticles (~13nm in diameter) are solid bodies that are embedded within and bound to the paint compounds. This has additional advantages insofar as there are no substance released during its formulation, or when applying the paint. Silver Nanoparticle Surface Coating A new silver nanoparticle based surface coating that eradicates fungi and bacteria has been developed by workers at the Institute for New Materials (Saarbrücken, Germany). The researcher’s claim that within every square centimeter of the material, there exists more than 1 billion silver ion releasing nanoparticles. The


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nanocoating can apparently be applied to virtually any metal, glass, or plastic surface within hospitals, public buildings, factories, and homes. Diamon-Fusion for Silica-Based Surfaces Diamon-Fusion International, Inc. (DFI) (San Clemente, CA) has developed a multi- purpose nanocoating product called Diamon-Fusion that seals and protects most surfaces that contain silicon dioxide (e.g., ceramic tile, porcelain, glass, granite). The company employs a two-step chemical vapor deposition process; the first step grows a cross-linked silicone film from just below a surface outward to which a second proprietary vapor is introduced. The second step functions to cap all of the exposed “dangling” atom chains that exist on the surface to significantly increase its hydrophobicity and durability. This chemical reaction ensures that no points of attachment remain, providing an ultra thin, optically clear, and highly resilient surface. The nanostructured coating is covalently bound to the surface, which means that it shares electrons with the surface material itself, and forms one of the strongest bonds possible. Water repellent coatings typically employ hydrogen-bridge bonds, which bind it to a surface, whereas covalent bonds have ten times this strength. A hand applied solution was formulated by DFI for the quick and simple application of its Diamon-Fusion nanocoating in the field. It purportedly functions in the same manner and has the same quality as the vapor deposition process. Fire Protective Nanocoatings A nanocoating made up of silicon dioxide (SiO2) nanoparticles was developed by workers at the Institute of Material Research at the Chinese Academy of Sciences (Shenyang, China) that exhibited outstanding fire resistance. The nanocoating showed continued resilience against fire in tests that were conducted after it was immersed in water. Flame retardant nanoparticles were also produced by adding nanolyered double hydroxides and titanium dioxide nanoparticles to ammoniumpolyphosphate-pentaerythritol-melamine. Auburn University (Auburn, AL) researchers have investigated the thermal stability and degradation of heat and fire resistance of a polymeric composite with embedded nanoscale hard particles. Interest in nanocomposites continues to grow due to their enhanced thermal and barrier properties over conventional larger scale counterparts. Flame retardancy has been demonstrated in polymers that are filled with nanoparticles such as clay, carbon nanotubes, or silica (e.g., Nylon 6/montmorillonite and polypropylene/grafted polypropylene fumed silica fiber).


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Anti-Graffiti Nanocoating A nanotechnology enabled anti-graffiti coating called NANOSTONE ANTIGRAFFITI has been formulated by NANOBIZ.PL Ltd., (Warsaw, Poland). The coating is applied and polished on nonporous surfaces and can be sprayed on porous surfaces of almost any building material. It consists of hydrophobic nanoparticles that are formulated within a solution having low viscosity. When applied to porous substrates they can reach and chemically bind to the inner pore surfaces within building materials, rendering them hydrophobic to external moisture, yet porous enough at the microscopic level, to allow the release of vapors that are generated by the building materials themselves. Thus an edifice maintains breathablility. In addition to offering protection for buildings against graffiti spray paints and markers, the manufacturer states that NANOSTONE ANTIGRAFFITI can also shield against soil and water stains, posters, gums, tags, algae, mold, dust, soot as well as oil and aqueous substances. The solvent free, environmentally compatible, and UV resistant coating is durable for 6 years and resistant up to 10 graffiti removal events. Ceramic Thin Film Electrochromic Windows SAGE Electrochromics, Inc., (Faribault, MN) incorporates a vacuum sputtered five layered solid state coating infused with nanoscale electrochromic metal oxides onto its SageGlass windows. The cumulative thickness of the multilayer is about 2 microns. When a “clear state” window is activated by a low-voltage current (