Conference Programme - INASCON 2017

21-24th August 2017 Wills Hall, Bristol

Conference Programme

Contents

Letter from the Committee

INASCON 2017 Committee

About INASCON

About the University of Bristol

About the BCFN

Wills Hall Information

Our Sponsors

The Royal Society of Chemistry

Evening Activities

Workshops

Invited Speakers

Invited Talks Monday

Tuesday

Wednesday

Friday

Student Talks Tuesday

Wednesday

Student Talks

Thursday

Acknowledgements

Talk Abstracts

22

Silver nanoparticle embedded nucleotide hydrogel networks templated by novel coacervates Sam Briggs1, Avinash J. Patil1, Stephen Mann FRS1 1

Centre for Organised Matter Chemistry, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom

A microdroplet suspension, formed via novel complex coacervation, of a polycation, poly(allylamine hydrochloride) (PAH), and a nucleotide, guanosine monophosphate (GMP); can undergo hydrogelation upon addition of an inorganic stimulus. First, PAH and GMP condense to form spherical droplets of polymer-rich solution within a polymer-poor solution via entropic and electrostatic interactions [1].

Figure 1: Phase contrast and fluoresence micrographs of novel PAH GMP coacervate suspension stained with Hoescht 33258 dye. Subsequent addition of silver ions added to the surrounding polymer-poor phase can abstract protons from the amine groups of the GMP, forming a silver stabilised GMP complex. Self-association of the complexes within the microdroplets leads to the formation of 1D nano-filaments which sequester water as a result of hydrophilic outer moieties, to form a hydrogel network [2]. The GMP, being localised within the coacervate microdroplets, forms spherical micro-hydrogel compartments. Initial results of the hydrogelation of the novel system are presented here utilising NMR and quantitative nanoscale characterisation (QNAFM) to illustrate the formation of the hydrogel, and AFM and TEM to elucidate the structure in the coacervate microdroplets. The system could then be exploited as a functional nanostructure template, as the silver present in the system can be reduced upon exposure to UV light to form anti-microbial nano-particles [2], and as such the system presents itself as an interesting avenue for further anti-microbial and non-membrane bound drug delivery platform technology research. References: [1] John Crosby et al., Chem Commun., 2012, 48, 11832-11834 [2] Jyotirmayee Dash et al., Soft Matter, 2011, 7, 8120-8126

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Exploring the antibacterial property of silver nano-triangles synthesized using biocompatible polymers Sailee Shroff1, Jussi Toppari2 and Leona Gilbert1 1

Department of Biological and Environmental Science, Nanoscience Center, University of Jyväskylä, Finland 2 Department of Physics, Nanoscience Center, University of Jyväskylä, Finland

Hospital acquired infections (HAIs) are becoming a common concern amongst healthcare professionals, largely due to the development of antibiotic resistant organisms. Some of the common preventive strategies listed by the CDC, such as autoclaving cannot be used on all types of devices, ethylene dioxide gas is highly toxic to the hospital patient and staff and ethylene dioxide gas plasma has an extremely expensive set up. Due to these short comings, the above listed sterilants are not able to cater to all class of hospitals and all types of medical devices2. In an attempt to overcome these limitations, silver nano-triangles (AgNTs) were exploited for their inherent anti-microbial property against the most commonly known HAI of Escherichia coli. For their known biocidal activity and lower cytotoxicity, silver nano- triangles were synthesized using biocompatible polymers like polyethylene glycol (PEG) and poly(sodium) styrene sulphonate (PSSS). Characterization with UV-Vis spectroscopy, displayed a broad peak near the infrared end of the visible spectrum due to the in plane dipole resonance and a shoulder between 350-400 nm due to the quadrupole resonance, peculiar to nanotriangles. Transmission electron microscopy was used to physically characterize the particles and confirm their triangular shape. The average edge length of PEG AgNTs varied from 40 to 50 nm and for PSSS AgNTs 20-30 nm (thickness was ~5 nm). The antibacterial property was examined by studying the effect of nanoparticles on growth curve of Escherichia coli. At higher dilution ratios of nanoparticles to media like 3/4, a clear antibacterial effect was observed for both the types of AgNTs. However, lower dilution ratios like 1/2, 1/4 and 1/8 only revealed a reduction in growth. With these positive preliminary results, silver nano-triangles could further be explored for their toxicity and immuno stimulatory effects on cells. References 1. Quinn M. M. and Henneberger P. K, Am. J. Infect. Control. 43(2015), 424 2. Knetsch M.L.W. and Leo H.K, Polymers. 3(2011), 340

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Designing the ideal bactericidal surface Irill Ishak1,2, Angela Nobbs1, Wuge Briscoe2 and Bo Su1 1

2

School of Oral and Dental Sciences School of Chemistry2, University of Bristol

Previous theoretical work by Pogodin et al. and Xue et al. on the mechanics of bactericidal effect on the nanopatterned surfaces show that optimal bactericidal surface can be achieved with specific dimensions of the nanofeatures on the surface. According to Xue et al., sharper pillars and less dense pillars provide better bactericidal activity compared to the one found on cicada wing [1, 2]. Recently, another model on the bactericidal effect of the nanopillars suggests that one can have higher bactericidal properties if the surface has broader and denser pillars. The aim of this project is to understand how the differences in topography effects the bactericidal properties [3]. Anodised alumina oxide (AAO) has been found to be a simple and versatile method to make a reusable template for polymeric nanopillars that mimic the topography found on the cicada wings. To make uniform nanopillars, the aluminium sheet was first polished and anodised. Then, the second anodisation step was performed to create the uniform nanopores. This AAO will be served as the master template, and the pattern is transferred onto the PET sheet using the hot embossing technique. Two samples were designed to have same nanopillar spacing with a different diameter to assess the effects of nanopillars diameter on the bactericidal properties. The spacing of the nanopillars is 100nm while the diameter is 40nm and 80nm. Bactericidal properties of the test surfaces were determined using Live/Dead assay where the percentage of dead cells were calculated. AFM will be used to measure the adhesion energy of the surfaces and to understand how differences in nanotopography affecting the bactericidal properties of the surfaces. References 1. Pogodin, S., Hasan, J., Baulin, V.A., Webb, H.K., Truong, V.K., Nguyen, T.H.P., Boshkovikj, V., Fluke, C.J., Watson, G.S., Watson, J.A. and Crawford, R.J. (2013) Biophysical model of bacterial cell interactions with nanopatterned cicada wing surfaces. Biophysical journal, 104(4) pp.835 – 840 2. Xue, F., Liu, J., Guo, L., Zhang, L. and Li, Q., (2015). Theoretical study on the bactericidal nature of nanopatterned surfaces. Journal of theoretical biology, 385, pp.1-7. 3. Li, X., (2016). Bactericidal mechanism of nanopatterned surfaces. Physical Chemistry Chemical Physics, 18(2), pp.1311-1316.

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Biomimetic extra-cellular matrix for the mechanical modulation of stem cell fate N. Mincy 1 S. Bo2 D. Sean3 M. Paolo4 1

Bristol Centre for Functional Nanomaterials, University of Bristol 2 Oral and Dental Sciences, University of Bristol 3 Department of Chemistry, University of Bristol, 4 Department of Clinical Sciences, University of Bristol

We developed a biomimetic extra-cellular matrix made of gelatin nanofibers for mechanically modulating the cardiac stem cells. Gelatin nanofibers were electrospun in a pure water solvent system by maintaining appropriate humidity and temperature for the first time ever. An in situ cross-linking method with a double barrel syringe was used to cross-link the gelatin nanofibers with 1-Ethyl-3-(3 dimethylaminopropyl) carbodiimide (EDC) in combination with Nhydroxysuccinimide (NHS). Different parameters such as concentration, flow rate, applied voltage and distance between the needle tip and collector were studied to optimize the morphology and size of gelatin nanofibers. The optimized gelatin nanofibers were then crosslinked externally with Glutaraldehyde vapor (Glu) and characterized using Scanning Electron Microscope (SEM). Fourier Transformation Infra-red (FT-IR) spectroscopy analysis was done to confirm the cross-linking and ninhydrin assay was performed to find out the degree of crosslinking. Dissolvability studies were also carried out to confirm the nanofibrous structure of the scaffolds are retaining even after immersed in Phosphate Buffer Saline (PBS). The cardiac pericytes isolated from the surgical leftovers of patients having congenital heart defects were seeded on the scaffolds to study the viability, adhesion and proliferation. Immunocytochemistry assays were also done to check whether the cells are maintaining the stemness and phenotypes. The results showed that the developed gelatin nanofibrous scaffolds were beadles with a diameter of 200nm. The gelatin nanofibers were well cross-linked both internally and externally using EDC/NHS and Glu and were stable enough to be used as a good candidate for mechanically modulating cardiac pericytes. The cell studies showed that the developed gelatin nanofibrous scaffolds were non-toxic and behave as an extra-cellular matrix for the cells to adhere, proliferate and differentiate while maintaining the stemness and phenotype. Keywords: electrospinning, gelatin, stem cells, congenital heart defects, tissue engineering.

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Fibronectin Adsorption as a Key Mediator in the Nanotopographical Control of Cell Behaviour Elie Ngandu Mpoyi1, Marco Cantini1, Paul M. Reynolds1, Nikolaj Gadegaard1, Matthew J. Dalby2, Manuel Salmeron-Sanchez1. 1

Division of Biomedical Engineering, School of Engineering, University of Glasgow, Glasgow G12 8LT, United Kingdom 2 Center for Cell Engineering, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom. Nanotopography surface is widely used to influence cell behaviour and in particular controlled disorder has been shown to be important in cell differentiation/maturation. Nonetheless, extracellular matrix proteins, such as fibronectin (FN), initially adsorbed on a biomaterial surface are known to mediate the interaction of synthetic materials with cells. We examine the effect of nanotopography on cell behaviour through this adsorbed layer of adhesive proteins using a nanostructured polycarbonate surface comprising 150 nm-diameter pits originally defined using electron beam lithography. We address the effect of this nanopitted surface on FN adsorption and subsequently on cell morphology and behaviour using C2C12 myoblasts. Wettability measurements and atomic force microscopy imaging showed that protein is adsorbed both within the interpits spaces and inside the nanopits. Cells responded to this coated nanotopography with the formation of fewer but larger focal adhesions and by mimicking the pit patterns within their cytoskeleton, nanoimprinting, ultimately achieving higher levels of myogenic differentiation compared to a flat control. Both focal adhesion assembly and nanoimprinting were found to be dependent on cell contractility and are adversely affected by the use of blebbistatin. Our results demonstrate the central role of the nanoscale protein interface in mediating cell-nanotopographical interactions and implicate this interface as helping control the mechanotransductive cascade. References 1. Ngandu Mpoyi E, Cantini M, Reynolds PM, Gadegaard N, Dalby MJ, Salmeron-Sanchez M. 2016. Protein Adsorption as a Key Mediator in the Nanotopographical Control of Cell Behavior. ACS Nano 10: 6638-6647.

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Ultrasonic traps for tissue engineering V. Levario-Diaz a, A. Barnes b and M. C. Galan a* School of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, UK. Department of Physics, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK.

a b

Keywords: Acoustic trapping - cell manipulation - tissue engineering The development of techniques for trapping and patterning of cells is of importance in tissue engineering 1 and assessment of cytotoxicity. A definite cellular composition is present in each tissue where inter- and intracellular interactions depend on a specific spatial distribution 2. Current methods for patterning cells rely on magnetic, electrical and optical forces 3,4, though successful, these techniques often employ specialized equipment and are costly. Here, we present a linear array of live cells created with a two-dimensional ultrasonic trapping device. The arrangement is achieved using a square ultrasonic-engineered device with small electronically integrated transducers. By employing acoustic radiation forces, cells are driven to the pressure nodes where alignments are formed. To fully characterise the device, Comsol modelling analysis was employed to simulate the acoustic pressures cells are experiencing. Frequencies and voltages of the piezoceramic transducers are controlled to preserve viability of HeLa cells and optimise cell adherence efficiency. Temperature experiments were performed as a function of time and voltages to have an optimal cell trapping method. Furthermore, we show that the cell alignments are maintain after 24 hours and that ultrasonic trapping is a versatile and non-invasive technique with promising application in tissue engineering and regenerative medicine. References 1 Biomed Microdevices (2012) 14: 559-564. 2 Lab Chip, 2014, 14, 2266. 3 Lab Chip, 2013, 13, 1003. 4 Anal Bioanal Chem (2006) 385: 408-412.

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Isolation and characterization of tumour-derived extracellular vesicles P.Beekman1,2, A. Nguyen1, S. Le Gac2, C.J.M. van Rijn1 1

Organic Chemistry, Wageningen University & Research, Wageningen, The Netherlands 2 MIRA, University of Twente, Enschede, The Netherlands

Realtime monitoring of cancer patients can improve their therapy, compared to body scans (e.g. PET-CT) performed only at a few moments during treatment. A well-established technique is monitoring the concentration of circulating tumour cells (CTC) in a blood sample. However, the robustness of the information obtained from these samples, named liquid biopsies, suffers from the low concentration of CTC (~1/ml). In this project, extracellular vesicles (EVs) are studied as a potential candidate to replace CTC as a screening target in liquid biopsies. EVs are nanoscale bioparticles shed by cells through various processes. There is evidence that the concentration of tumour-cell-derived EVs in metastatic cancer patients is correlated with their prognosis. This suggests that EVs are a promising biomarker. In addition, the abundance of EVs (~103/ml) is much higher than that of CTC, which would greatly improve the predictive power of liquid biopsies. The goal of the project is to develop a device for the isolation of EVs from patient blood and the quantitative characterization of the obtained samples. Isolation of EVs on surface modified microfabricated chips was demonstrated. Porous silicon microfluidic chips were fabricated topdown and grafted with a hydrogel polymer1. Antibodies were covalently conjugated to the polymer. EVs were captured from sample flows and individually detected using confocal microscopy (see Figure 1).

Figure 1: Confocal micrograph of tumor-derived extracellular vesicles captured on antibodygrafted surface

References 1. Nguyen A T, Doorn R van, Baggerman J, Paulusse J M J, Klerks M M, Zuilhof H, Rijn C J M van, Adv. Mat. Interfaces 2 (2015)

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Fluorescent carbon-based multivalent nanoplatforms for glycan presentation Stephen A. Hill1*, Dr. David Benito-Alifonso1, Dr. Sean Davis1, Dr. Monica Berry2, Dr. Carmen Galan1 1

School of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, UK. 2 School of Physics, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK.

*[email protected] Carbohydrates expressed on cellular surfaces are presented in a multivalent fashion. This “cluster-glycoside effect” is used by Nature to compensate for weak-binding events between single saccharides and carbohydrate-binding proteins i.e. lectins.1 Platforms that recreate this multivalent presentation represent a good biomimic of the cell surface, our group recently showed that the type of glycan presented on the surface of a fluorescent CdSe/ZnS quantum dots (QDs) had an effect on intracelular uptake, furthermore a QD coated with lactose and a non-internalisable sugar were up-taken into HeLa and human corneal epithelial cells (Araki-Sasaki).2 Although we showed that glycan density mitigates the inherent toxicity of CdSe QDs, these nanodots remain less than ideal for in vivo applications. To broaden the scope of functional nanomaterials for biomedical applications, it is of the utmost importance to develop non-toxic and stable nanomaterials that can be used over long periods of exposure.3 Carbon-based fluorescent nanomaterials have shown great potential as an alternative. Carbon dots (CDs) are a relatively recent discovery that have QD-analogous photoluminescence properties e.g. tuneable fluorescence, but crucially are also highly water soluble, easily functionalized and have benign toxicity profiles.4 Herein, we report the facile and fast synthesis (three minutes) of a new class of fluorescent CDs using microwave-assisted irridation from simple and cheap molecular precursors, in the presence of surface passivating agents.5 Novel features, not previously described in other CDs were identified including a sp3nanocrystalline core and important incorporation of chlorine into the CD architecture, which contributed to quantum yield. Subsequent surface manipulations on the CD can afford glycancoated CDs (Figure 1) which have been investigated for their cellular uptake, toxicity profile and their potential use as carbohydrate multivalent platforms. Plus, small reaction modifications allow interesting features to be integrated into the system such as tuned fluorescence and sub-cellular localisation.

Figure 1: Synthetic outline for carbohydrate-coated carbon dots Acknowledgements The financial support of the Bristol Chemical Synthesis CDT and EPSRC. References: 1. Lundquist, J. J., Toone, E. J. Chem Rev., 2002, 102, 555 2. Benito-Alifonso, D., Tremel, S., Hou, B., Lockyear, H., Mantell, J., Fermin, D. J., Verkade, P., Berry, M., Carmen Galan, M., Angew. Chem. Int. Ed., 2014, 53, 810. 3. Hardman, R. Environ. Health. Persp., 2006, 114, 2, 165. 4. Baker, S. N., Baker, G. A., Angew. Chem. Int. Ed., 2010, 49, 6726. 5. Hill, S. A., Benito-Alifonso, D., Morgan, D., Davis, S., Berry, M., Carmen Galan, M., Nanoscale, 2016, 8, 18630

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Nanoporous Protein Crystal Biohybrid Materials N. Abu El Magd1 1

School of Chemistry, University of Bristol, Bristol

Host-guest complexation systems have emerged as a means of synthesising novel nanocomposite materials, whereby specific, adaptable hosts form the template for the incorporation and confined synthesis of ‘guest’ species.1 These complexes present much more than a passive template for synthesis; they form structurally-adaptive host-guest systems which are capable of responding to multiple stimuli. As a consequence, they have been developed for many applications, including catalysis, drug-delivery, storage and separation.2 Nanoporous protein single crystals were used as a periodic scaffold and reaction vessel for the synthesis of novel functional composite materials. Unlike conventional porous inorganic solids, protein crystals are held together by non-covalent forces and combine the softness of a structurally adaptive host with the regularity and rigidity of a crystalline material. They possess a regular array of solvent channels, which are 0.5 – 10 nm in size and encompass 30-65% of the total crystal volume, providing very high internal surface areas of 800- 3000 m2g-1.2 These solvent channels exhibit unique, confined environments that can be exploited as discrete reaction vessels. As a result, nanoporous lysozyme single crystals have been utilised as organised templates for the intra-crystalline synthesis of metallic nanoparticles and nanoarrays, conducting polymers and carbon dots. 3–5 References 1. Horike S, Shimomura S, Kitagawa S, Nat. Chem. 1 (2009), 695–704. 2. Guli M, Lambert E, Li M, Mann S, S.Angew. Chemie. 122 (2010), 530 – 533. 3. England M, Patil A, Mann S, Chemistry. 21 (2015), 9008-9013. 4. England M W, Lambert E M, Li M, Turyanska L, Patil A J, Mann S. Nanoscale. 4 (2012), 6710. 5. Muskens O L, England M W, Danos L, Li M, Mann S. Adv.Funct.Mater. 23, (2013), 281-290.

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Sensing of metal cations based on surface enhanced Raman scattering P. Piotrowski1,2, D. Jimenez de Aberasturi2, M. Henriksen-Lacey2, J. Langer2, L. M. Liz-Marzán2,3,4 and J. Bukowska1 1

Faculty of Chemistry, University of Warsaw 2 CIC biomaGUNE 3 Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine, Ciber-BBN, 4 Ikerbasque, Basque Foundation for Science Detection of cations is of great importance from biological point of view. While some play a crucial role in the human body (such as Na(I), K(I), Ca(II), Mg(II)), other are extremely toxic, even in small concentrations (e.g. Pb(II) or Hg(II)). Development of a quantitative and effective way of intracellular metal ion sensing poses a real challenge. Even though some analytical methods based on mass spectrometry or electrochemical techniques have been successfully introduced as techniques for ion determination, their main drawback is that they cannot be easily applied in living cells. This issue can be overcome by optical sensors using surface-enhanced Raman scattering (SERS), where a Raman active molecule, called a Raman reporter, is attached to a metal nanoparticle. The spectrum of the Raman reporter is sensitive to a chosen analytical parameter. In this report, we present the use of silver nanoparticles functionalized with 2-mercaptoethanesulfonate anion (MES) molecules as SERS cation nanosensors. Detection of various cations was possible thanks to two SERS marker bands of MES assigned to SO3- stretching vibrations. Ions were distinguished based on the position of one of the bands (e.g. 1066 cm-1 for Na+, 1076 cm-1 for Ca2+). Moreover, its intensity normalized to the intensity of the second marker band at 1040 cm-1 provided information about the cation concentration1. Mapping of the cell sample resulted in detection of intracellular K+ ions (Figure 1). Differences in ion distribution may be observed: higher concentrations occur in the middle of the cell and lower concentrations towards the cell membrane. This might be connected with dynamics of endosomal ion concentration. Obtained results make our nanosensor a promising candidate for ion sensing in biological and biomedical applications.

Figure 1. Optical image of the cells (left) and the SERS map (right). Green scale shows the intensity ratio of Raman marker bands, spots in the shades of grey mark the areas without MES spectrum. References 1. Piotrowski P and Bukowska J, Sens Actuator B 221 (2015) 700

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Radical induced supramolecular hybrid hydrogelation Mr. Matthew Mulvee1,2, Dr. Natasa Vasiljevic1, Dr. Avinash Patil2 & Prof. Stephen Mann2 1 Bristol Centre for Functional Nanomaterials, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, United Kingdom 2 Centre for Organized Matter Chemistry & Centre for Protocell Research School of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom Hydrogels are comprised of a continuous 3D network of non-fluid, elastic filaments that extend throughout an aqueous solvent and entangle to form a viscoelastic material. These are extremely versatile due to the vast range of materials that can comprise the gel matrix and the many stimuli that can trigger gelation. Due to their remarkable chemical, physical and biological properties, these soft materials are employed in a myriad of applications such as tissue engineering, biosensing, biocatalysis, sustained drug release etc.1,2 Herein, first ever use of radicals to form a supramolecular hydrogel is reported, thereby expanding the synthetic methodologies. The formed hydrogelator self-assembles into highaspect ratio nanofilaments that entangle to form a self-supported viscoelastic hydrogel. The interconnecting nanofilaments were visualised via TEM and high-resolution AFM. The latter surprisingly revealed periodically twisted fibres with left-handed chirality, corroborated with CD analysis, which is uncommon in the hydrogels produced by the same hydrogelator via conventional means. We envisage that this methodology should open new routes to alter the molecular packing of gelator molecules to construct novel chiral supramolecular architectures.

a

b

a) AFM micrograph showing the twisting of individual nanofilaments (arrows indicate the location of twisting) b) CD spectra demonstrating opposite ellipticity between hydrogel samples The cause of the unanticipated helicity will be explored via FT-IR, NMR, SANS and CD studies, while further characterisation of the gel will be achieved using microscopy, rheological techniques, and DSC (1) (2)

Peppas, N. A.; Hilt, J. Z.; Khademhosseini, A.; Langer, R. Adv. Mater. 2006, 18 (11), 1345–1360. Estroff, L. a; Hamilton, A. D. Chem. Rev. 2004, 104 (3), 1201–1217.

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Femtosecond laser induced local functionalization of graphene by oxidizing groups and defects Jyrki Manninen1, Pasi Myllyperkiö2, Jukka Aumanen2, Juha Koivistoinen2, Vesa-Matti Hiltunen1, Pekka Koskinen1, Mika Pettersson2 and Andreas Johansson1, 2 1

2

Nanoscience Center, Department of Physics, University of Jyväskylä, Finland Nanoscience Center, Department of Chemistry, University of Jyväskylä, Finland

Graphene is a two-dimensional conductive material with exotic charge carrier properties and high mechanical strength. The tuning of the properties on a two-dimensional graphene lattice locally can provide wider functionality and new possibilities for graphene based applications. Two patterning methods that allow local functionalization of graphene by femtosecond laser have been developed at University of Jyväskylä. A femtosecond laser induced process can be used to add oxygen groups as functional groups to a graphene lattice1. The method allows gradual treatment and continuous tuning of the conductance of graphene locally from pristine graphene to fully insulating graphene oxide. The method can be used to draw insulating features on graphene without breaking the lattice. Another femtosecond laser induced process can be used to “optically forge” graphene surfaces by laser pulses into 3D structures (graphene blisters)2. The treatment induces defects into the graphene lattice which leads to additional strain and expansion of the graphene layer. The method allows patterning and tuning of 3D graphene structures in height range of a couple of nanometers to hundreds of nanometers. Patterns drawn by both patterning methods are presented in figure 1.

Figure 2: The logo of University of Jyväskylä patterned on graphene by femtosecond laser induced oxidization and 3D forging. a) A femtosecond four-wave mixing signal map of an oxidized logo pattern. b) A scanning electron microscope image of the same oxidized pattern as in a. c) An atomic force image of an optically forged 3D logo. References 1. J. Aumanen et al. Nanoscale 7 (2015) 2851. 2. A. Johansson et al. Submitted (2017).

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In-situ dissolution study of cerium oxide nanoparticles in liquid-cell TEM Muhammad Sajid Ali Asghar1, Beverley Inkson1 and Günter Möbus1 1

Nano LAB Centre, Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD, UK

Ceria nanoparticles are a successful ingredient in many products and devices. Most applications use the nanoparticles suspended in liquid, and therefore the nanoscale behaviour of many particles needs to be studied in-situ with sub-nm resolution in TEM. Here we use a liquid cell in TEM: In this experiment we have selected ceria nanoparticles (CNP) and ceria nanorods (CNR) immersed in de-ionised water. We have explored the movement of CNPs, radiolytic dissolution of CNPs1 as shown in figure 1, and high intensity chemical reactions (generation of new phases and bubble formation)2. The whole process of wet electron irradiation is based on the thickness of water, electron beam changing pH and generating ions or radicals in water. The mentioned results have great importance for different research application fields like biomedical, catalysis, polishing, environmental cleaning (water treatment), nuclear engineering and anti-corrosion coatings.

Figure 1: Life radiolytic dissolution of ceria NPs in water (scale bar of 25nm for (a to d) & 10nm for (e to h)). References: 1. Asghar M. S. A., Inkson B., and Möbus G., ChemPhysChem 18 (2017) 1-6 2. Asghar M. S. A., Inkson B., and Möbus G., (Submitted for publication)

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Covalently linked multimers of thiolate-stabilized gold clusters Karolina Sokołowska1, Tanja Lahtinen1, Eero Hulkko1, Tiia-Riikka Tero1, Ville Saarnio1, Johan Lindgren1, Mika Pettersson1, Hannu Häkkinen1,2, Lauri Lehtovaara1. Departments of Chemistry1 Physics2 Nanoscience Center, University of Jyväskylä P.O. Box 35, 40014, Jyväskylä, Finland We present synthesis, separation, and characterization of covalently-bound multimers of paramercaptobenzoicacid (p-MBA) protected gold nanoclusters.1 The generality of the linking chemistry is proven with multimers of three different sizes of monodisperse pMBA-protected (para-mercaptobenzoic acid) clusters with 102, ~250 and ~500 gold atoms with several different dithiols. Preliminary results demonstrate control over the reaction yields of different superstructures, allowing production of superstructures in optimal conditions. TEM analysis in combination with MD simulations suggests that the nanoclusters are covalently bound via a disulfide bridge between dithiol molecules. Absorption spectroscopic studies of multimers indicate plasmonic coupling over the ~1 nm gap between the linked clusters. This achievement of making well-defined metallic nanoscale superstructures opens new possibilities in rational design of nanoscale devices with the precision of a single atom.

Figure 1: Left: Atomistic view of a linked Au102(p-MBA)44 dimer with biphenyl-4,4’dithiols. Right: TEM images of a) monomeric, b) dimeric and c) trimeric d) tetrameric Au~250 MPCs. References: 1. T. Lahtinen, E. Hulkko, K. Sokołowska, T.-R. Tero, V. Saarnio, J. Lindgren, M. Pettersson, H. Häkkinen, L. Lehtovaara, Nanoscale, 2016, 8, 18665–18674.

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Magnetic field-mediated growth of organic crystals from solution J. Walton1, S. Hall,2 1

Bristol Centre for Functional Nanomaterials, University of Bristol, Bristol 2 School of Chemistry, University of Bristol, Bristol

The crystallisation behaviour of organic molecules is of great relevance to many applications, from the processing and efficacy of pharmaceuticals to the study of materials for organic electronics. Crystallisation from solution or melt under applied electric fields is widely used in industry, whilst the application of magnetic fields is much less widely explored. Recently, an unforeseen polymorph of the polyaromatic hydrocarbon coronene was discover during solution growth at 2 T, illuminating the possibility of controlling the crystal growth of other systems in this manner. This work explores the introduction of static magnetic fields as a means of altering the growth behaviour of organic crystals from solution, in particular the charge-transfer complex TCNQcoronene, investigating the potential to affect the morphology, growth rate and crystal structure by application of magnetic flux densities in the range 1 - 15 T.

Figure: Alignment of crystals under increasing applied magnetic field strengths. References [1] Potticary, J. et al. Nature Communications, 7(May):11555, 2016.

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Ultra-thin film metal nanoparticle composites of benzimidazolium based anion exchange polymers for fuel cell application Bertoncello, Paolo1, Jones, Thomas1, Hernandez, Sandra1, Thomas, Owen2 and Holdcroft, Steven2 1 Swamsea University, Swansea, United Kingdom, SA2 8PP, UK 2 Department of Chemistry, Simon Fraser University, Burnaby, Canada Modification of glassy carbon electrodes (GCE) by films of a soluble and highly conductive benzimidazolium hydroxide based ionomer (PMBI) are reported for the first time. HMT-PMBI was synthesised by the procedure of Holdcroft et. al.[1] Drop cast films of varying concentrations (0.05-5 wt%) were characterized using a variety of electrochemical techniques (Cyclic Voltammetry, CV and Chronocoloumetry, CC). CVs showed the effectiveness of the ionomer films in preconcentrating anionic redox mediators species such as K4Fe(CN)6 and also demonstrated the permselectivity of such films by repelling positively charged redox mediators, such as Ru(bpy)3Cl2. CC was used to estimate the apparent diffusion coefficient and to elucidate the effect of polymer concentration on the charge transport properties within the polymer films. To explore potential electrocatalytic and electroanalytic applications, the PMBI-films were tested towards detection of anionic analytes in food such ascorbic acid and sulphites. Ionomer films were also selected as a template for the synthesis of metallic Pt and Pd nanoparticles (NPs). This was achieved by utilizing the ionomers anion conducting properties to incorporate the anionic salts of the metal within the polymer films, followed by in situ reduction with NaBH4. These Ionomer-metal NP composite electrode materials were investigated towards electrocatalytic reactions, including the oxygen reduction and hydrogen oxidation reactions in alkaline media. Ultra-thin Langmuir-Schaefer (LS) Ionomer films were then fabricated and functionalised using the method developed by Bertoncello et al.[2]. The Langmuir-Schaefer is a precise, versatile and relatively simple method, which allows for the formation of highly ordered molecular architectures with the advantage of controlling the thicknesses up to the molecular level. These ultra-thin films were investigated and compared to their drop cast film counterparts. 50

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E / V vs Ag/AgCl

Figure 1. CV Showing 5Layers of PMBI on ITO loaded Figure 2. CV Showing 20Layers of PMBI on GCE in 5mM K4Fe(CN)6 and scanned in 0.1M NaCl supporting Scanned in 0.5M H2SO4 after incorporation of Pd NPs electrolyte

[1] O. D. Thomas, K. J. W. Y. Soo, T. J. Peckham, M. P. Kulkarni and S. Holdcroft, Polym. Chem., 2011, 2, 1641 [2] P. Bertoncello, M. K. Ram, A. Notargiacomo, C. Nicolini, Phys.Chem.Chem Phys. 2002, 4, 4036

38

Electrochemical design of Au-Ag nanoplasmonic materials 1

V. Cruz San Martin1, N. Fox2, A. Sarua2, N. Vasiljevic2 Bristol Centre for Functional Nanomaterials, H. H. Wills Physics Laboratory, University of Bristol, Bristol 2 H. H. Wills Physics Laboratory, University of Bristol, Bristol

Development of new plasmonic materials is driven by the variety of advanced applications in optics, photovoltaics, and sensing.1-3 One of the most important application has been a large signal enhancement that can be achieved in surface-enhanced Raman spectroscopy (SERS) to probe single molecules and their interaction with the surfaces.4, 5 High signal enhancement occurs on metallic nanostructures of dimensions much smaller than the wavelength of light.1 Nanostructured Ag and Au are considered the best plasmonic materials for SERS. The Ag-Au system is a model system important in many nanotechnology applications such as catalysis, sensing and nanomedicine.6 The recent experimental and theoretical studies on AgxAu1-x nanoalloys and alloy derived nanostructures, i.e. as nanoporous gold (NPG) and nanoporous silver (NPS), suggest that control of the geometry, and composition can lead to discovery of new optical phenomena.3, 6 Here we will present controlled design of AgxAu1-x alloys using electrodeposition. Electrodeposition of AgxAu1-x alloys currently used in industrial/ electronics applications has been based on very harsh and toxic chemicals (such as cyanides).7 In this work, we will show that controlled alloy deposition can be achieved using environmentally friendly thiosulphate based solutions in the low-cost, room temperature set up. We found that the composition of the alloys can be varied by controlling the ratio of Ag and Au ions concentrations in the electrolyte. The microstructure, chemical composition and uniformity of the alloys (~200 nm thickness) have been confirmed by using SEM and AFM respectively. Furthermore, electrochemical treatment of the Au-Ag alloys was used to create more complex nanoporous plasmonic structures such as NPG). Examination of the SERS activity of the developed electrodes was done by using the micro-Raman scattering using chemical markers, such as Rhodamine 6G (R6G). References 1. Barnes, W. L.; Dereux, A.; Ebbsen, T. W., Nature, 2003, 424, 824-830. 2. Jain, P. K.; Huang, X.; El-Sayed, I. H.; El-Sayed, M. A., Accounts of Chemical Research, 2008, 41, 1578-1586. 3. Wang, D.; Ji, R.; Albrecht, A.; Schaaf, P., Beilstein J Nanotechnol, 2012, 3, 651-657. 4. Gong, C.; Leite, M. S., ACS Photonics, 2016, 3, 507−513. 5. Lal, S.; Grady, N. K.; Kundu, J.; Levin, C. S.; Lassiter, J. B.; Halas, N. J., Chem Soc Rev, 2008, 37, 898-911. 6. Biener, J.; Nyce, G. W.; Hodge, A. M.; Biener, M. M.; Hamza, A. V.; Maier, S. A., Adv. Mater., 2008, 20, 1211-1217. 7. Bozzini, B.; De Gaudenzi, G.P.; Mele, C., J. Electroanal. Chem., 2004, 1, Vol. 563, 133143.

39

Investigating the role of the organic cation in hybrid organic-inorganic perovskites using ultrafast infrared spectroscopy of formamidinium lead iodide perovskite V.C.A. Taylor*, D. Tiwari*, M. Duchi*, D.J. Fermin*, P. Donaldson†, I.P. Clark†, T.A.A. Oliver* *

†

School of Chemistry, University of Bristol, Bristol, BS8 1TS Central laser facility, Rutherford Appleton Laboratory, Harwell campus, Oxford

Hybrid organic-inorganic perovskites are remarkable materials with a plethora of unusual properties, including high absorption coefficients over a broad range of wavelengths, tunable bandgaps, long carrier lifetimes, high and balanced charge carrier mobilities, and very low excition binding energies1-3. These properties, combined with low-cost manufacture through solution processing and a resilience to impurities, have led to perovskites becoming a forerunner among novel materials research. Perovskites have potential applications in light emitting devices, thin film transistors, optoelectronics, spintronics and, most notably, photovoltaics. This year a new record for perovskite photovoltaics power conversion efficiency was set at 22.1%4, over a five-fold increase in the 7 years since perovskites were first demonstrated as photovoltaic materials6. This rapid advance is the result of intense work on these materials, however, the underlying reasons for perovskite’s unique properties are still unclear despite extensive study. Hybrid organic-inorganic halide perovskites consist of organic cations caged within an inorganic lattice of metal and halide atoms. It has been shown that the organic cation can modify the lead iodide crystal lattice structure and that perovskites containing the formamidinium cation exhibit a red-shifted bandgap compared to organic halide perovskites containing smaller cations1. Some studies have proposed that the ability of the cations to rotate within the lattice plays an important role in the high efficiency of the charge separation and extraction5, potentially forming ferroelectric domains at room temperatures.6 Ultrafast spectroscopy provides an ideal tool to elucidate these mechanisms as it enables monitoring of materials on timescales commensurate with that of molecular vibrations and rotations. We report the use of 2D infrared spectroscopy to demonstrate the rotation of formamidinium cations within a lead iodide perovskite sample on a picosecond (10-12 s) timescale. The timescale of this motion is significantly greater than those of previously studied systems and may be a key factor in the high power conversion efficiency of formamidinium perovskite over perovskites containing different cations. References 1 G.E. Eperon, S.D. Stranks, C. Menelaou, M.B. Johnston, L.M. Herz, and H.J. Snaith, Energy Environ. Sci. 7, 982 (2014). 2 G. Xing, N. Mathews, S. Sun, S.S. Lim, and Y.M. Lam, Science 342, 344 (2013). 3 P. Gao, M. Grätzel, and M.K. Nazeeruddin, Energy Environ. Science 7, 2448 (2014). 4 W.S. Yang, B.-W. Park, E.H. Jung, N.J. Jeon, Y.C. Kim, D.U. Lee, S.S. Shin, J. Seo, E.K. Kim, J.H. Noh, and S.I. Seok, Science 356, 1376 (2017). 5 M.C. Gélvez-Rueda, D.H. Cao, S. Patwardhan, N. Renaud, C.C. Stoumpos, G.C. Schatz, J.T. Hupp, O.K. Farha, T.J. Savenije, M.G. Kanatzidis, and F.C. Grozema, J. Phys. Chem. C 120, 16577 (2016). 6 J.M. Frost, K.T. Butler, F. Brivio, C.H. Hendon, M. van Schilfgaarde, and A. Walsh, Nano Lett. 14, 2584 (2014).

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Mechanical properties of freestanding ultrathin perovskite membranes Y. A. Birkhölzer1, V. Harbola2, S. S. Hong2, S. Crossley2, D. Lu2, H. Y. Hwang2,3 1

Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands 2 Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA 3 Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA At least since the discovery of monolayer graphene, two-dimensional materials have attracted worldwide attention. Currently a lot of work is being performed on metal dichalcogenides, exciting new physical states and prototype devices with novel functionalities have been shown. The fabrication of freestanding quasi two-dimensional single-crystalline perovskite films, however, proved to be much harder. While the growth of these materials on single crystal substrates has been studied for decades, the challenge remained to separate these layers from the growth substrate, limiting the manipulation capabilities with respect to exfoliated materials. In this talk, I would like to show a new, general synthesis route to produce freestanding perovskite membranes developed by the Hwang group at Stanford University. The key is the epitaxial growth of water-soluble Sr 3Al 2O 6 on perovskite substrates by Pulsed Laser Deposition, followed by in situ growth of functional films and heterostructures. Millimetresize single-crystalline membranes are produced by etching the sacrificial layer in water, providing the opportunity to transfer the films onto arbitrary substrates and integrate them with heterostructures of semiconductors and layered compounds. While our team already published the fabrication route, TEM, electrical and magnetic data1, I will show some yet unpublished data on the mechanical properties of freestanding ultrathin perovskite films. The Young’s modulus of ultrathin strontium titanate (SrTiO3), a model perovskite material, was derived from force-distance curved measured with an Atomic Force Microscope in force mapping mode at ambient conditions. The possibility to manipulate freestanding perovskite structures opens the way to fabricate for instance chemically resistant, piezoelectrically driven, all-oxide MEMS devices for biomedical applications.

Schematic view of the fabrication route. Figure adapted from Lu et al.1 References 1. Lu et al., Nature Materials 15, 1255–1260 (2016). DOI: 10.1038/nmat4749

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Organic Thermoelectric Thin Films based on Polymer/Quantum Dot Hybrids H. Haseeb, H. Karl, W. Brütting Experimental Physics IV, Institute of Physics, University of Augsburg, 86135 Augsburg, Germany Conductive polymers among other energy conversion materials have recently shown great potential for harvesting heat into electrical power for green, flexible wearable electronic gadgets. Thermoelectric materials allow the conversion of a temperature gradient along the material into useful electrical power. Utility of thermoelectric materials originates from the Seebeck effect. A temperature difference impels a flow of charge carriers from the hot to the cold side and generation of an electrical potential. This thermal voltage is dependent on the magnitude of the temperature difference, but also on the intrinsic material properties, such as electrical and thermal conductivity and the Seebeck coefficient. A high electrical and a low thermal conductivity leads to a high conversion efficiency but they cannot be varied independently. Materials with high efficiency developed in the past had been based on inorganic semiconductors or metal alloys and include heavy elements such as bismuth, tellurium, lead and arsenic. Overcoming the scarcity, economic, health and environmental problems of the elements used in past, we attempt to fabricate and characterize organic-inorganic nanocomposite thermoelectric thin films with environmental friendly counterparts. Our hybrid thermoelectric thin films comprise the polymer blend PEDOT: PSS and ZnO nano particles (NPs) yielding a nanocomposite with enhanced thermoelectric properties - allowing it to be a drop-in replacement for many different materials while keeping other properties unaltered. ZnO NPs were prepared by a room temperature solution growth technique. Isocyanato functional groups were hosted on the surface of ZnO NPs by introducing 3isocyanatopropyltriethoxysilane (3-ICPTES) as a coupling agent. ZnO NPs were further bonded to PEDOT: PSS polymer blend via urethane linkages by the reaction of isocyanato caped ZnO NPs and hydroxyl groups from Ethylene Glycol (EG) molecules diffused into PEDOT:PSS during post treatment. Heating up to 200°C and increasing weight percent of mechanically mixed ZnO NPs in PEDOT:PSS increased Seebeck coefficient of thin films to a maximum constant value of 33µV/K at 1 weight percent (Wt%). Enhanced electrical conductivity of 833 S/cm was achieved at 0.1 Wt% of ZnO NPs but indicated a rapid decrease at higher temperature beyond 100°C and at higher weight percent of NPs. Increasing the amount of NPs also increased the viscosity of PEDOT:PSS before spin coating. Subsequently, power factor linearly increased with temperature yielding a maximum value of 21.5 μW/K 2m at 200°C for the EG post treated films without NPs. An optimum power factor of 14 μW/K2m was achieved for 0.1 Wt% of ZnO NPs at room temperature with no prominent change at higher temperature up to 200°C.

42

Hybridization of carbon/metal oxides for electrochemical energy storage S. Fleischmann,1,2 M. Zeiger,1,2 and V. Presser1,2 1

INM – Leibniz Institute for New Materials, Saarbrücken, Germany 2 Saarland University, Saarbrücken, Germany

A successful transition from fossil fuels to renewable energy sources highly depends on the availability of efficient electrochemical energy storage devices to bridge the fluctuations of intermittent wind or solar power. The development of novel electrode materials that enable fast charging/discharging rates and high lifetime is at the focal point of current research activities. Supercapacitors using porous, high surface area carbon electrodes exhibit a rapid and highly efficient charge storage, yet their specific energy is too low to meet requirements for mobile applications and electric vehicles.1 A promising strategy for increasing their specific energy, while maintaining high power and cyclability, is the hybridization of carbon with Faradaic materials that are commonly used in batteries. In this talk, the design strategies for hybrid electrode materials will be laid out and the key findings of our ongoing research will be presented. What is the ideal pore structure of the substrate? Carbon/vanadium oxide hybrid electrodes are synthesized via atomic layer deposition (ALD). We use both activated carbon and carbon onions as representatives of substrate materials with high internal and external surface area, respectively. While internal porosity of activated carbon readily becomes blocked with increasing VOx loading, carbon onions enable continuous deposition of VOx within their large interparticle voids.2 How to further increase the energy storage capacity of Faradaic coatings? Capitalizing on the cyclic character of ALD, we decorate carbon onions with alternating stacks of vanadium oxide and titanium oxide. By inserting a certain amount of TiO2 in between atomic layers of VO2, an expansion of the VO2 unit cell can be achieved. Electrochemical characterization reveals a highly increased lithium intercalation capacity into the mixed oxide structure, effectively increasing the specific capacity of the hybrid electrode from 200 mAh/g to 380 mAh/g.3 References 1. Béguin F, Presser V, Balducci A and Frackowiak E, Adv. Mater. 26 (2014) 2219-2251 2. Fleischmann S, Jäckel N, Zeiger M, Krüner B, Grobelsek I, Formanek P, Choudhury S, Weingarth D and Presser V, Chem. Mater. 28 (2016) 2802-2813 3. Fleischmann S, Tolosa A, Zeiger M, Krüner B, Peter N J, Grobelsek I, Quade A, Kruth A and Presser V, J. Mater. Chem. A 5 (2017) 2792-2801

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Colloidal Particles: One Approach To Study The Structure and Dynamics of Molecular Machines Mauleon-Amieva, A. 1, 2, 3, 4, Hallett, J. 1, 2, Duijneveldt, J. S. 3, and Royall, C. P. 1, 2 1

2

HH Wills Physics Laboratory, University of Bristol, Bristol, UK., BS8 1TL. Centre for Nanoscience and Quantum Information, Tyndall Avenue, Bristol, UK., BS8 1FD. 3 School of Chemistry, Cantock's Close, University of Bristol, Bristol, UK., BS8 1TS. 4 Bristol Centre for Functional Nanomaterials. University of Bristol. Bristol, UK., BS8 1TL. Email: [email protected]

From the estimation of Avogadro's number by Jean Perrin's experiments in 1923, to the study of many fundamental subjects in condensed matter physics, i.e. glass structure, colloidal particles play a crucial role as hard-sphere model systems [1, 2]. Equilibrium statistical mechanics describe the phase behaviour of these colloidal dispersions in the same way as they were atoms or molecules. Furthermore, the interparticle interactions can be modified to obtain fluid, glassy and close-packed structures. In addition, colloidal dispersions are susceptible to external field forces [3], e.g. DC electric fields, displaying phase behaviour far from equilibrium, such as self-propulsion [4]. Here we describe an electric-driven model as an approach to study the dynamics of molecular machines, e.g. flagellar motors, based on a previous model describing torque transmission in soft devices [5]. References 1. Pusey, P. N. & van Megen, W. Phase behaviour of concentrated suspensions of nearly hard colloidal spheres. Nature 320, 340 (1986). 2. Poon, W. PHYSICS: Colloids as Big Atoms. Science (80-.). 304, 830{831. issn: 00368075 (2004). 3. Blaaderen, A. V. Colloids under External Control. MRS Bull. 29, 85{90. issn: 0883-7694 (2004). 4. Bricard, A., Caussin J.-B., Desreumaux, N. & Dauchot O. Bartolo, D. Emergence of macroscopic directed motion in populations of motile colloids. Nature 503, 95{98 (2013). 5. Williams, I. et al. Transmission of torque at the nanoscale. Nat. Phys. 12, 98{103. issn: 1745-2473 (Oct. 2015).

44

Combustion of a hydrogen-oxygen mixture in nano-bubbles as an actuation principle 1

H.Y. Witteveen, 2V.B. Svetovoy and 1G.J.M. Krijnen 1

2

University of Twente, Enschede Rijksuniversiteit Groningen, Groningen

Miniaturization of systems can reduce costs, and may offer properties that larger systems do not have. Micro-actuators are required to drive these systems. Traditional actuators suffer from scaling problems on the microscale. Electromagnetic actuators become relatively weak, and existing combustion engines do not work on the microscale since reactions quench in small volumes. Recently, the reaction between hydrogen and oxygen was observed in nano- and microbubbles.1 The bubbles containing a mixture of gases were produced in microsystems using electrochemical decomposition of water with a fast switching of voltage polarity. It was observed that nano-bubbles could combust spontaneously at room temperature. In Figure 3, bubble generation is shown for alternating polarity pulses of different frequencies. At frequencies of 20 kHz, a large amount of bubbles is generated, comparable to single polarity pulses. At higher frequencies, less bubbles are produced, indicating recombination of H2 and O2. Changing the duty cycle, i.e. the ratio of H2 and O2 generated at one electrode, increases visible gas production, reinforcing the evidence that a reaction between the two gases is responsible for the disappearance of the gas. Using the self-combusting properties of these nano-bubbles, a micro-actuator is fabricated which can deliver high forces by electrochemically producing gas, and can actuate fast by releasing the pressure due to self-combustion of nano-bubbles.2 Figure 4 shows the deflection of an actuator membrane based on this principle. Pressure is increased due to an applied voltage, and is decreased rapidly when the voltage is turned off.

Figure 3: Bubble generation after 1 ms of electrolysis. At high frequencies, gas production is significantly lower.

Figure 4: Deflection of the actuator membrane. At t = 0 s, voltage is turned on and gas production induces deflection of the membrane. At t = 600 µs, the voltage is turned off and the pressure is released swiftly.

References 1. Svetovoy, V., et al., Overcoming the fundamental limit: Combustion of a hydrogenoxygen mixture in micro-and nano-bubbles. Energies, 2016. 9(2): p. 94. 2. Svetovoy, V.B., et al., Combustion of hydrogen-oxygen mixture in electrochemically generated nanobubbles. Physical Review E, 2011. 84(3): p. 035302.

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Nanoscale material characterisation: The use of a modified DVD pickup in High-speed Atomic Force Microscopy Freddie Russell-Pavier,1,2 Oliver Payton1, Loren Picco1, John Day1, Tom Scott1 and Andrew Yacoot2 1

Interface Analysis Centre, University of Bristol, Bristol, UK National Physical Laboratory, Teddington, Middlesex, UK

2

Optical pickups have been developed over several decades for reading and writing of optical discs such as CD, DVD and Blu-ray. In operation, optical pickups are conducting the complex task of automatically 3D tracking and reading a spiral of embedded pits on the underside of the optical disc that can extend up to several tens of kilometers in length and less than 500 nm in width. This is performed with the use of a compact laser and a single quadrant photodiode. The optical system makes use of an astigmatic lens, which has two focal planes in orthogonal axes that focus to different focal lengths. It has been shown in previous studies how optical pickups can be incorporated into a range of experimental set-ups [1-4]. We integrate a DVD optical pickup to monitor the dynamics of a micro-mechanical beam or ‘cantilever’ which has a near atomic ‘sharp’ tip. The tip is traversed across a given surface at high-speeds and can reconstruct a topographical surface map. We demonstrate highspeed atomic force microscopy within a novel instrument with low build cost and increased bandwidth over traditional techniques. This work builds upon the development of the world’s fastest contact mode high-speed atomic force microscope conducted at the University of Bristol.

Figure 1: A instrument schematic of the novel high-speed AFM (middle) with example data presented and labelled (left & right) By making use of the high throughput and the sub-nanometer resolution achieved with a modified optical pickup within a bespoke instrument, outlined in Figure 1, surface properties and nanoparticle identification can be conducted on a sub-second timescale. This rapid analysis generates large statistical datasets allowing sample wide representative properties to be measured quickly. Work with the National Physical Laboratory (NPL) assesses the metrological capabilities of the pickup and seeks to implement measurement traceability. References [1] F.Quecioli et al., Review of Scientific Instruments, 1999, Vol. 70, Issue 9, pp 3620-3624 [2] K.Fan et al., Measurement Science and Technology, 2002, Vol. 14, pp 47-54 [3] E.Hwu et al., Appl. Phys. Letters, Vol. 91, Issue 22, pp 221908:1-3 [4] C.Chu et al., Measurement Science and Technology, 2007 Volume 18, Issue 7, pp 1831-1842

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Additive manufacture of shape-changing soft materials through open source technology K. Oliver1, A. Seddon1,2, R. Trask3 and S. Eichmann4 1

Bristol Centre for Functional Nanomaterials, University of Bristol, Bristol 2 School of Physics, University of Bristol, Bristol 3 Department of Mechanical Engineering, University of Bath, Bath 4 Department of Aerospace Engineering, University of Bristol, Bristol

Nature has many examples of multifunctional, responsive architecture. This work combines additive manufacture, also known as 3D printing, with stimuli responsive materials to emulate this. We aspire to create responsive materials in arbitrary shapes, capable of moving in complex ways, directly from the printer – 4D printing.1 This technology would open up an entirely new design space and many opportunities. Hydrogels are an appealing model material for 4D printing due to their ease of modification and similarity to certain biological tissues. While far from traditional hard engineering materials, their soft compliant properties have potential applications in soft robotics and interfaces, in addition to bioprinting applications.2,3 Our current work focuses on fused filament deposition of thermoresponsive hydrogels using an in-house modified open-source 3D printer. Inspired by the gel structures and composites found in nature, we have developed previous work on poly-isopropyl acrylamide-alginate double network hydrogels4 and incorporated Figure 5. An open-source delta 3D printer producing shaped alginate hydrogels nanoparticles which alter mechanical properties and thermal response. We show that these nanoparticles modify the rate of thermoresponse of the double network gel, and show some examples of printed actuating structures using thermoresponsive gels. References 1. Oliver, K., Seddon, A. & Trask, R. S. Morphing in nature and beyond: a review of natural and synthetic shape-changing materials and mechanisms. J. Mater. Sci. 51, (2016). 2. Bauer, S. et al. 25th anniversary article: A soft future: from robots and sensor skin to energy harvesters. Adv. Mater. 26, 149–61 (2014). 3. Gross, B. C., Erkal, J. L., Lockwood, S. Y., Chen, C. & Spence, D. M. Evaluation of 3D printing and its potential impact on biotechnology and the chemical sciences. Anal. Chem. 86, 3240–53 (2014). 4. Bakarich, S. E. et al. 3D/4D Printing Hydrogel Composites: A Pathway to Functional Devices. MRS Adv. 1–6 (2015). doi:10.1557/adv.2015.9

Poster Abstracts

48

Structural Characterisation of Temperature Sensitive Hierarchical Hydrogels S. Fussell1, J. Van Dejneveldt1 and CP Royall2 1

School of Chemistry, University of Bristol, Bristol 2 School of Physics, University of Bristol, Bristol

Poly(N-isopropylacrylamide) (pNIPAM) is a “smart” microgel that has a volume phase transition temperature (VPTT) around 30°C, making this material of great interest for biomedical applications2. At the VPTT the microgels significantly shrink, up to 100 times in volume, along with a large loss in the volume fraction of water inside the particle1. It was recently discovered that when concentrated mixtures of pNIPAM microgel particles were mixed with a certain polymeric surfactant, a transition occurs where at the VPTT the system changes from a viscous liquid to a solid gel. Although this transition has been identified, the driving forces behind the gel formation and the structure of the network formed are little understood. As part of an initial investigation, at high polymer concentrations a gel network could be observed using fluorescence microscopy. However, the resolution of the technique used was not sufficient to observe the intricate gel structure. As part of this work, super resolution microscopy techniques will be used to obtain high resolution images of the gel network in order to observe finer structural detail. The structure of the gel was investigated initially using dynamic light scattering, to obtain information about the microgel size and the interaction of the microgel with surfactant at low concentrations. Alongside this, the structure of the gel was imaged using a range of techniques including fluorescence, confocal and stimulated emission by depletion (STED) microscopy. References 1. B. Erman and P. J. Flory, Macromolecules, 19 (1986) 2342. 2. Y. Guan and Y. Zhang, Soft Matter, 7 (2011) 6375.

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The “Not So Great” Pyramid of Enschede Henk-Willem Veltkamp1, Xingwu Sun2, Erwin Berenschot2, Han Gardeniers2, Niels Tas2 1

Micro Sensors and Systems Mesoscale Chemical Systems MESA+ Institute for Nanotechnology, University of Twente, Enschede, NL 2

During the 4th dynasty of Egypt, the great pharaoh Khnum-Khufu ordered to build a colossal pyramid-shaped tomb for himself. This is the oldest of the Seven Wonders of the Ancient World and is nowadays known as the Great Pyramid of Giza. Four and a half thousand years later history repeated itself, but now with a drastic miniaturization and opening up of the faces of the pyramid. Instead of using stone, the great nanofabrication pharaoh’s of the University of Twente used silicon and silicon nitride. The quest to make the “Not So Great” Pyramid of Enschede started with the fabrication of a micro-sized pyramid, which was already a splendid seven orders of magnitude smaller than the Great Pyramid of Giza. This pyramid was not used to contain the remains of the nanofabrication pharaoh’s, but for trapping and containing living cells [1] (figure 1, right image). But the journey was not over yet. With the use of the advanced lithography technique laser interference lithography (LIL) [2] a further miniaturization is achieved. This nano-sized pyramid is now a marvelous nine orders of magnitude smaller than the Great Pyramid of Giza (figure 1, left image). We were able to trap gold nanoparticles (NPs) in this membrane with open pyramidal cages (figure 2). These cages ensure a traceable location for the NPs during analysis, even after subsequent processing (i.e. chemical modification). On the poster the fabrication scheme, fabrication results, electron miscopy and elemental analysis studies on the traceable positions of the gold NPs and an outlook to a further miniaturization via Displacement Talbot Lithography is shown.

Figure 1. The two generations of miniaturized pyramids. Right: the micropyramid (107 times smaller than the Great Pyramid of Giza) with trapped cell, and left: the nanopyramid fabricated via LIL (109 times smaller), with a 1:1 size comparison.

Figure 2. Top view electron microscope images of the membrane with trapped Au NP. References 1. E.J.W. Berenschot, N. Burouni, B. Schurink, et al., Small, 24 (2012), 3823-3831 2. X. Sun, H.-W. Veltkamp, E.J.W. Berenschot, et al., MEMS, 29 (2016), 185-188

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Flexible and environmental friendly graphene based smart textiles 1

Gopika Rajan1, Ana Neves1, Monica Craciun1 College of Engineering, Physical Sciences and Mathematics, Univeristy of Exeter, Exeter, UK

The field of wearable electronics is a fast-growing market expected to be worth 50 billion euros in 2025, over three times the current market. The main challenge facing current wearable devices is that intrusive solid electronic attachments limit the usage of established devices in wearable systems. Integration of electronic functions within fabrics, with production methods fully compatible with textiles, is therefore of current interest, to enhance performance and extend functions of textiles. Graphene, which has outstanding mechanical, optical and electronic properties, has been demonstrated as potential candidate for application in smart textiles which are stretchable and flexible. The current study involves the influence of fibre topography and the impact of ultraviolet-ozone treatment on the fibre surface. The various studies involves sheet resistance measurements for graphene coated textile fibres. Tensile strength studies of the textile fibres has also been included in the current study.

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DFT calculations of aluminium on diamond Michael C. James1,2, Paul W. May1 and Neil L. Allan1 1 2

School of Chemistry, University of Bristol, Bristol

Bristol Centre for Functional Nanomaterials, University of Bristol, Bristol

Thin layers of metals deposited on the diamond surface can induce a negative electron affinity (NEA), where the conduction band lies higher in energy than vacuum. The dipole formed between diamond and the electropositive metal causes band bending at the surface. This is of interest for applications including photodiodes, electron emitters and renewable energy generation. Previous experimental and computational studies have looked at group I and II metals [1] and 1st row transition metals [2,3] on the diamond surface. Whilst many of these metals can induce a NEA on diamond, it is also essential to have a stable surface. For instance, whilst Cs on diamond has a large NEA, and work function of just 1.5 eV, it is not thermally stable above 400 °C.[4] This work looks at aluminium as a potential metal. DFT calculations were performed for Al on the bare and O-terminated diamond C(100) surface up to 1 monolayer. Aluminium displays a modest (negative) electron affinity of up to ~ -1 eV, but does have a large adsorption energy, particularly on the O-terminated diamond surface.

Fig. 1. Side and plan view of 1 monolayer of aluminium on O-terminated 2×1 reconstructed C(100) diamond surface. Grey=carbon, red=oxygen, yellow=aluminium.

References 1. K. M. O’Donnell, T. L. Martin and N. L. Allan, Chem. Mater., 2015, 27, 1306–1315. 2. P. K. Baumann and R. J. Nemanich, J. Appl. Phys., 1998, 83, 2072. 3. A. K. Tiwari, J. P. Goss, P. R. Briddon, N. G. Wright, A. B. Horsfall and M. J. Rayson, Phys. Status Solidi, 2012, 209, 1697–1702. 4. K. P. Loh, J. S. Foord, R. G. Egdell and R. B. Jackman, Diam. Relat. Mater., 1997, 5, 874– 878.

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Development of Ultra-Thin Magnetic Films via Surface Limited Redox Replacement Method H. Li and N.Vasiljevic Bristol Center for Functional Nanomaterials, School of Physics, University of Bristol, Bristol

The magnetic properties of ultrathin films depend strongly on their atomic-scale structure. The crystallographic orientation and the presence of atomic defects can have a significant effect on the magnetic behavior such as the atomic spins orientation.1 Therefore, an atomic-scale control of the structure and composition of the interfaces is required in order to develop new magnetic layers for various applications (such as hard disc reading heads, spin valve structures for random-access memories, magneto-optic media).

Here we will present the development of a new electrodeposition method based on the surface limited redox replacement (SLRR) approach. The SLRR method is based on the galvanic replacement of an epitaxial layer of underpotentaily deposited metal by a more noble metal at the open circuit potential (OCP).2 Underpotential deposition (UPD) is a unique electrochemical process of metal ion Mn+ deposition on the substrate at the potential more positive than the equilibrium potential of Mn+/M.3 In this poster, we demonstrated Ni growth by SLRR method on Au thin-film substrates using Zn UPD.

We studied the Zn UPD on Au and Ni in phosphate and boric acid solutions with pH ~4.5. The effect of the crystal structure on the Zn UPD process was studied via cyclic voltammetry. The study has shown that on annealed Au samples the characteristic Zn UPD peaks have more pronounced Au (111) features and the effect of ion adsorption is more pronounced. The Zn UPD in borate solution has been shown to be more suitable for the SLRR growth of Ni. The chronoamperometry was used to establish a suitable potential for forming a complete Zn UPD layer on Au and subsequently to grow Ni layer at OCP. The AFM technique was used to characterize and compare the quality of Ni films before and after the first few cycles of Zn SLRR.

References 1. Tserkovnyak Y, Brataas A and Bauer G E W, Phys. Rev. B. 66 (2002) 224403 2. Vasilic R, Dimitrov N, Electrochem. Sol. Stat. Lett. 8 (2005) C173 3. Takahashi S, Aramata A, Nakamura M, Hasebe K, Taniguchi M, Taguchi S and Yamagishi A, Surf. Sci. 512 (2002) 37-47

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Multifunctionalized Carbon Dots, a suitable target for Drug Delivery Systems Sylvain Penasse, Stephen A. Hill and M. Carmen Galan* School of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, UK

Synthetic strategy for drug delivery systems

Doxorubicin is one of the drug currently used as part of the chemotherapy treatment of cancer patients. However, this compound possesses severe side-effects (ranging from the inconvenient hair loss to detrimental heart attack) due to a lack of selectivity toward cancerous cells. The maximum dosage that can be administered to a given patient is thus restricted and as a result, it is often not sufficiently efficient to treat patients successfully. In recent years, interest in the development of improved therapies to treat cancer in a more selective and efficient manner has grown exponentially. However, the ability to target specific cells or organelles in order to minimise side effects is still a challenge. One of the approaches that has been developed entails the use of delivery systems that carry an inactive drug (prodrug) that can be released and then become active when the desired location has been reached. A number of such delivery systems appear to be promising, however none are currently used as pharmaceuticals, likely due to a lack of solubility of the complex (polymer based nanoparticles), lack of targeting ability and also due to the potential toxicity (Gold or CdSe/ZnS-based nanoparticles) associated with the carriers. Our group has already reported that a carbohydrates coating act as trojan horse for cell internalisation1 and recently reported the practical three-minute synthesis of amine-coated fluorescent CDots ready to be functionalised with a given biomolecule.2-3 Furthermore, we also demonstrated that the CDots exhibit no significant toxicity in cell based studies of a 7 day period of incubation. Herein, we report on the development of a new doxorubicin-delivery system, which employs non-toxic fluorescent carbon-based nanoparticles. Moreover, initial cell internalization studies where carried out which demonstrated the ability of the novel conjugate to be internalised in HeLa cells.

1

Benito-Alifonso D., Tremel S., Hou B., Lockyear H., Mantell J., Fermin D. J., Verkade P., Berry M. and Galan M. C. Angew. Chem. Int. Ed. 53 (2014) 810-814. 2 Hill S. A. and Galan M. C., Beilstein J. Org. Chem. 13 (2017) 675-693. 3 Hill S. A., Benito-Alifonso D., J. Morgan D., Davis S. A., Berry M. and Galan M. C. Nanoscale 8 (2016) 18630-18634.

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Modification of Clay Minerals with ω-Amino Acids for Use in Dental Cements M. L. Sosa Madrid1,2,3, J. S. van Duijneveldt1, M. E. Barbour2 1

2

School of Chemistry, University of Bristol, Bristol. Oral Nanoscience, School of Oral and Dental Sciences, University of Bristol, Bristol. 3 Bristol Centre for Functional Nanomaterials, University of Bristol, Bristol

Amines adsorb strongly to smectites such as montmorillonite resulting in intercalated materials (organoclays). Adsorption of omega-amino acids (ω-aa) has the added interest that the modifier itself can be polymerised into a nylon, thus allowing for in-situ polymerisation resulting in a clay nanocomposite1. The use of polymer nanocomposites as nanofillers for layered silicates (clays) has been developed lately, these materials offer enhancement in several properties for the final application. One potential use of such ω-aa modified clay is as a nanofiller in a dental filling material known as a glass ionomer cement (GIC). A GIC is an acid-base cement composed primarily of alumina-silica-calcium fluoride glass embedded in a polyacrylic acid matrix. GICs are widely used in dentistry and have many clinically favourable properties, but they lack strength and this limits their applications. One of the treatments proposed in the literature works by adding 12aminododecanoic acid (ADA) to a clay, this helped to increase the compressive strength of the GICs. Nevertheless, it has been mentioned that one of the challenges for mixing clays with GICs is the technique used to get the clay well dispersed into the GICs.2,3 The overarching aim of this work is to establish whether ω-aa modified clays could be used to increase tensile and compressive strength of GICs. In this study, we treated clay with ADA and with 6-aminohexanoic acid (AHA) and characterised the organoclays using elemental analysis and X-ray scattering. Treatment is done from an aqueous dispersion of montmorillonite (MMT), either by room temperature mixing or by acid treatment at 80 ºC. Small-angle X-ray scattering (SAXS) revealed that ADA treatment resulted in a larger increase in basal layer spacing than AHA, in line with the difference in chain length. However, for AHA an excess had to be added in order to achieve a good intercalation. In contrast with the ADAMONT, the clay modified with AHA fully exfoliates into water. The compressive strength testing results of GICs modified with 2 wt% of these clays revealed a new challenge. It is necessary to determine the appropriate ratio between the powder and liquid components of the GIC to get a proper specimen that could be comparable to the control, in order to determine if the modification with our nanocomposite material is enhancing the strength. 1

Kato C., Kuroda K., Misawa M. (1978). Preparation of Montmorillonite-Nylon complexes and their thermal properties. Clays and Clay Minerals, 129-136. 2 Dowling, A. H., Fleming, G. J. (2007). The impact of montmorillonite clay addition on the in vitro wear resistance of a glass-ionomer restorative. Journal of Dentistry, 309-317. 3 Dowling, A. H., Stamboulis, A., Fleming, G. J. (2006). The influence of montmorillonite clay reinforcement on the performance of a glass ionomer restorative. Journal of Dentistry, 802810.

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Sticky Stem Cells: Reengineering the Cell Membrane using Nanobiohybrid Materials Rosalia Cuahtecontzi Delint 1,2,3,4, Terry McMaster 2,3, Wael Kafienah1 & Adam Perriman1 1 2

The School of Cellular and Molecular Medicine, University of Bristol, BS8 1TD

The Bristol Centre for Functional Nanomaterials, University of Bristol, BS8 1FD 3 4

The School of Physics, University of Bristol, BS8 1TL

The School of Biochemistry, University of Bristol, BS8 1TD

Email: [email protected]

Regenerative medicine is a rapidly emerging field that commonly involves the integration of synthetic or natural scaffolds and stem cells to provide functional tissue for autologous grafts. One of the challenges in this process is the efficiency of strong, localised and rapid adhesion of stem cells when injected directly or seeded on scaffolds. To address this issue, we describe the rational design of a new type of cell membrane active nanobiohybrid, which can spontaneously insert into the membrane of human mesenchymal stems cells (hMSCs) and provide increased adhesion to both natural and synthetic scaffolds. Significantly, it has recently been shown that a sequence found in a growth factor has an extremely high binding capacity 1 for proteins found in the extracellular matrix (ECM) . This sequence was fused to a charged 2 fluorescent protein (FP), which has shown to actively bind to the hMSC membrane , to build a protein construct. Electrostatic assembly was used to build a polymer surfactant corona at the 34 surface of the construct without the loss of protein function , , which could further increase the cell membrane affinity. By combining these three elements it will be possible to display multiple copies of the nanobiohybrids on the membrane of hMSCs to promote the cell adherence to the ECM proteins including fibronectin, vitronectin, tenascin c, osteopontin and fibrinogen. 1. Martino, M. M. et al. Matrix Enhance Tissue Healing. 343, 885–889 (2014). 
 2. Cronican, J. J. et al. Potent delivery of functional proteins into Mammalian cells in vitro and in vivo using a supercharged protein. ACS Chem. Biol. 5, 747–52 (2010). 
 3. Brogan, A. P. S., Siligardi, G., Hussain, R., Perriman, A. W. & Mann, S. Hyper-thermal stability and unprecedented re-folding of solvent-free liquid myoglobin. Chem. Sci. 3, 1839 (2012). 
 Keywords: Stem cell, adhesion, cartilage, bionanoconjugate, nanobiohybrid.

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Evaluation of semi-conducting diamond films for thermionic emission G. Wan1 1

School of Physics, University of Bristol, Bristol

Thermionic emission occurs when electrons in a heated material gain enough thermal energy to overcome the work function, and are subsequently ejected from the material surface. This phenomenon has applications in energy conversion, vacuum diodes and electron guns. Due to the highly elevated temperatures required for usable thermionic emission current, applications in many devices are typically limited. Therefore, there is a need for low temperature thermionic emitter materials. Diamond has many unique physical and electrical properties such as electrical conductivity, work function and thermal conductivity which can be controlled during its growth. These properties play a crucial role in the thermionic emission of electrons. This poster focuses on determining the work function and the characterization of the dopants and surface terminations of diamond.

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AFM and Raman microspectroscopy study of polyaniline/montmorillonite intercalate and derived nanocomposite containing few-layer graphene P. Vilímová1, P. Peikertová1, J. Tokarský1, L. Kulhánková2 Nanotechnology Centre, VŠB – Technical University of Ostrava; Ostrava, Czech Republic 2 Faculty of Metallurgy and Materials Engineering, VŠB – Technical University of Ostrava; Ostrava, Czech Republic 1

Polyaniline/montmorillonite (PANI/MMT) intercalate is electrically conductive material which combines rheological properties of nonconductive montmorillonite and electrical properties of polyaniline. PANI/MMT intercalates can serve as a precursor for preparation of aluminosilicate nanocomposite containing in situ prepared few-layer graphene resulting in increase of conductivity. Graphene nanocomposites are usually prepared using commercially available graphene while syntheses of nanocomposites containing in situ prepared graphene are less common. In original method recently published by our research group1, the tablets from PANI/MMT intercalate powder compressed at 400 MPa were used and high-temperatureinduced (1400 °C) changes of PANI in the interlayer space of MMT under dynamic argon atmosphere led to aluminosilicate-graphene nanocomposite. In present work, use of the tablets and also PANI/MMT thin films on quartz glass substrate was studied. A cost of preparation was reduced, i.e., tablets and thin films were calcined at lower temperature (1300 °C) in static argon atmosphere. Raman microspectroscopy specified the types of carbon in calcined samples and confirmed the presence of few-layer graphene formed from PANI chains in both cases. Characterization of surface morphology and surface electrical properties of noncalcined and calcined samples were studied using atomic force microscopy and conductive atomic force microscopy. In the case of tablets, differences between internal volume (measured on the fracture of tablets) and surface were observed. Current distribution maps obtained by conductive atomic force microscopy showed an importance of MMT in few-layer graphene formation. Acknowledgement: This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic [grant numbers SP2016/63, SP2017/65]. References 1. P. Čapková, V. Matějka, J. Tokarský, P. Peikertová, L. Neuwirthová, L. Kulhánková, J. Beňo and V. Stýskala, J. Eur. Ceram. Soc. 34 (2014) 3111

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Electrochemically Self-assembled Nanoalloys Alicja Szczepanska1,2, Natasa Vasiljevic1,2 and Neil Fox1,2,3 1

Bristol Centre for Functional Nanomaterials, University of Bristol, United Kingdom 2 School of Physics, University of Bristol, United Kingdom 3 School of Chemistry, University of Bristol, United Kingdom

Electrochemically controlled self-assembled nanoalloys are materials which have not been fully explored yet. They are a great alternative to those produced in Ultra High Vacuum (UHV)1 because of their lower production cost at room temperature and ability to use in both nano- and microscale.2 Research of the surface stress driven self-assembly phenomena have been done on a fundamental level in UHV. However they have not been exploited in practical applications due to the high costs and lack of knowledge in the understanding of the behaviour of these materials outside a controlled vacuum environment. The electrochemical environment is an ideal but not much-explored route3 to design such functional materials because of easy control and scalability that would make the transfer to real and practical systems viable and versatile. These self-assembled structures on the monolayer level have an incredible potential for application in electrocatalysis, electronics and bio-sensing. This poster investigates the surface alloying process during underpotential deposition (UPD) of Pb onto Au(111).4 The UPD is an electrochemical phenomenon in which an epitaxial monolayer of metal (M) is deposited onto a metal substrate (S) at a potential less negative than the equilibrium potential for reduction of the metal M. The aim of the study is to establish the range of potential at which the alloy forms as well as its composition. The electrochemical results suggest that Pb-Au alloying happens during potential cycling at partial monolayer coverage(s) of Pb.3 This is manifested by the differences and irreversibility of the Pb UPD formation and dissolution. Although Pb and Au are two immiscible metals, the surface alloying is driven by a very large lattice mismatch of ~21% and the elastic energy minimisation. The conditions of thermodynamic equilibrium at different coverages of Pb on Au (0-1 ML) during formation and the dissolution of Pb UPD ML have been explored and compared. The effect of time of polarisation on the surface alloy structure and its stability is presented as well. References: 1. Basenbacher F.; Nielsen L.P.; Sprunger P.T., Surface alloying in heteroepitaxial metal-onmetal growth, in The chemical physics of solid surfaces King D.A. and Woodruff D.P., Editors. 1997, Elsevier. 207 2. Schwarzacher, W. Electrochem. Soc. Interface 2006, 15, 32-35. 3. Kukta, R. V.; Vasiljevic, N.; Dimitrov, N.; Sieradzki, K. Phys. Rev. Lett. 2005, 95, 186103. 4. Nutariya J.; Velleuer J.; Schwarzacher W.; Vasiljevic N. ECS Transaction 2006, 28, 15.

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Tamper-indicating materials for nuclear dismantling security A. Suriyakumaran1,2, 3, Dr A.J. Croxford2, Dr S.A. Davis3 1

Bristol Centre for Functional Nanomaterials, School of Physics, University of Bristol

2

Non Destructive Testing, School of Engineering, University of Bristol

3

School of Chemistry, University of Bristol

There are three components being investigated in the project, all of which have functioned so far as standalone concepts. All three components will be investigated for the purpose of tamper indication for nuclear dismantlement (industrial purposes). The three chosen components are as follows: silica sol gel, piezoelectric sensors and ‘shatter’ glass. Sol gel chemistry is a widely used wet chemical technique for synthesising inorganic materials from liquid sources; the samples are highly versatile materials that can be doped with dyes and nanoparticles for various objectives.1 Non-destructive testing can be used to inspect a sample without compromising it and without the need for active components.2 3 The ‘shatter’ glass component allows for the use of stress fields to ensure complete failure of the glass, which would provide a definitive sign for tamper inspection;4 such examples these glass types can be found in everyday use as phone screen protectors and fire alarm safety glass. (1)

Dislich, H.; Hinz, P. J. Non. Cryst. Solids 1982, 48 (1), 11–16.

(2)

Cheng Huan Zhong; Croxford, A. J.; Wilcox, P. D. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 2013, 60 (6), 1115–1125.

(3)

Zhong, C. H.; Croxford, A. J.; Wilcox, P. D. Proc. R. Soc. London A Math. Phys. Eng. Sci. 2014, 471 (2173).

(4)

Zaccaria, M.; Overend, M. In Challenging Glass 4 & COST Action TU0905 Final Conference – Louter, Bos & Belis (Eds); Taylor & Francis: London, 2014.

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Thickness mapping of multilayered nanostructures by Scanning Spectroscopic Ellipsometry (SSE) B. Hicham, Blanco. E and D. Manuel Departamento de Física de la Materia Condensada and Instituto de Microscopía Electrónica y Materiales, Universidad de Cadiz-11510 Puerto Real, Cádiz, Spain The optical response of different types of multilayered nanostructures was studied by means of spectroscopic ellipsometry. A variable angle spectroscopic rotating analyzer ellipsometer, J.A. Woollam V-VASE, was used to measure the ellipsometric angles, amplitude ratio (Ψ) and phase differences (Δ) between the reflected polarized light p and s components at different angles of incidence in the vicinity of the substrate’s Brewster angle. The ellipsometer is equipped with a computer controlled sample positioning system, with vertical sample mounting which allows a scan range of 50 x 50 mm X-Y with 0.1 mm step and spot sizes up to 0.2 mm. The effective optical constants and thicknesses of the films were then determined by constructing the corresponding dielectric function models and numerically fitting the recorded spectra to estimate Ψ and Δ from the selected model. As a result of modeling the whole optical response, nanometric thickness maps were obtained separately for each layer over a large sample area crossing the studied multilayered nanostructures.

Figure 1: Spectroscopic Ellipsometry mapping images of the 3-D periodic discontinous multilayers sample containing (a) one Au–Al2O3 nano-granular metal layer sandwiched between (b) two amorphous Al2O3 layers References [1] Bakkali H, Blanco E and Dominguez M, Nanotechnology 28 (2017) 335704. [2] Bakkali H, Blanco E and Dominguez M, De la Mora M B, Sánchez-Aké C and VillagránMuniz M, Applied Surface Science 405 (2017) 240-246.

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Toward Single Fibre-like Micelle Field-Effect Transistor. B. Flores Gomez1 C.F.J. Faul2 and I. Manners2 1 Bristol Centre for Functional Nanomaterials, University of Bristol, BS8 1TS, UK 2 School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK Nanotechnology and self-assembly polymers give a new point of view for nanoelectronics. While the silicon is the main semiconductor material in these fields, new materials start to emerge and create a new area: organic electronics. An organic field-effect transistor (OFET) has a configuration of a thin film transistor, a substrate (Si) with a thin film of the organic semiconductor (P3HT), an insulator layer and source-drain (S-D) electrodes (gold). The main aspect in the operation of the transistors is the charge carrier transport1. This property is measured by the mobility, µ, which describes how charge carriers move under the influence of an electric field2.The performance of the device depends in the interface between semiconductor and the electrodes and the interface of the semiconductors and insulators, since these interfaces are the place where we have the charge transport3. Polymers have a huge impact in the nanoelectronics fields, since they are being used as an organic material for electronics, in some cases, with same properties as the metal semiconductors and with the advantages of low cost and solution phase fabrication. Poly (3hexylthiophene) P3HT is one of the most used and promising polymers because it shows the highest charge-transport mobilities4. In this study, we focus in the fabrication and characterization of field effected transistors, and the measurements of mobility and conductivity using a single P3HT fibre-like micelle as active layer. P3HT fibres are being synthetized by living crystallization-driven self-assembly (CDSA) method, which allows the control of the length of the fibres.

Organic Field Effect transistor with a thin film of P3HT. a) Structure of the device b) AFM image of P3HT fibres5 References 1. Karl, N., Charge carrier transport in organic semiconductors. Synthetic Metals 2003, 133, 649-657. 2. Reese, C.; Roberts, M.; Ling, M.-m.; Bao, Z., Organic thin film transistors. Materials Today 2004, 7 (9), 20-27. 3. Don Park, Y.; Lim, J. A.; Lee, H. S.; Cho, K., Interface engineering in organic transistors. Materials Today 2007, 10 (3), 46-54. 4. Wöll, D. C., Physical and Chemical Aspects of Organic Electronics. From fundamentals to Functioning Devices. WILEY-VCH Verlag GmbH & Co. KGaA: Federal Republic of Germany, 2009. 5. Li, X., et Al. “Uniform electroactive fibre-like micelle nanowires for organic electronics.” Nature Communications 2017, 8, 15909.

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Characterising the Endocytosis and Intracellular Trafficking of Cylindrical Micelles J. Diego Garcia-Hernandez1, Holly Baum2, George Banting3 and Ian Manners4 1, 4 School of Chemistry, University of Bristol, Bristol. 2, 3 School of Biomedical Sciences, University of Bristol, Bristol. Abstract. Cylindrical micelles have shown to have many advantages for its use as drug delivery vectors (DDV), interestingly, in vivo models exhibit an increased retention time, up to ten times, when rodents are treated with cylindrical micelles, instead of reciprocal polymer spheres1. Endocytosis of cylindrical micelles has not been thoroughly studied, mostly because cylindrical morphologies are difficult to obtain and control2. Their use as potential DDV is being explored in this work, their size, shape and functional groups are key3–5. Herein, water soluble polymers, based on polyferrocenyldimethylsilane (PFS), are being used and preliminary results showed cell internalization, characterising the pathway micelles follow inside the cell is being studied. Synthesis of polymers, crystal driven self-assembly (CDSA), seeded crystal driven selfassembly (SCDSA), cell viability assays, and cellular uptake are presented. a)

b)

b)

d)

Figure 1. Seeded CDSA of a) PFS20-b-P2VP250 at 2 eq.; 5 eq.; 10 eq. b) respective graph of PFS20-bP2VP250 with PDI values for each equivalent, c) PFS29-b-P2VP336 at 2 eq.; 5 eq.; 10 eq. b) respective graph of PFS29-b-P2VP336 with PDI values for each equivalent. References (1) Geng, Y.; Dalhaimer, P.; Cai, S.; Tsai, R.; Tewari, M.; Minko, T.; Discher, D. E. Nat. Nanotechnol. 2007, 2 (4), 249–255. (2) Gilroy, J. B.; Gädt, T.; Whittell, G. R.; Chabanne, L.; Mitchels, J. M.; Richardson, R. M.; Winnik, M. A.; Manners, I. Nat. Chem. 2010, 2 (7), 566–570. (3) Cohen, M. L. Science (80-. ). 1992, 257 (5073), 1050–1055. (4) Kataoka, K.; Harada, A.; Nagasaki, Y. Adv. Drug Deliv. Rev. 2001, 47, 113–131. (5) Rai, M.; Ingle, A. P.; Gupta, I.; Brandelli, A. Int. J. Pharm. 2015, 496 (2), 159–172.

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3D-printed graphene-based electroactive gels for flexible energy storage Christian P Romero1, Jonathan Rossiter2, Charl F J Faul3 1

BCFN, School of Physics, University of Bristol, Bristol, BS8 1TL, UK 2 School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK 3 Dept. of Engineering Mathematics, University of Bristol, Bristol BS8 1TH, UK Conducting polymers (CPs) are synthetic polymers with the ability to conduct electrons and provide flexibility and processability not found in metal conductors. An important application of CPs is their use in electroconductive hydrogels (ECHs), as a single component or as an additive with other components to form 3D hydrogel networks structures.1,2 Poly(aniline), PAni, is a conductive polymer that can be used in different redox states and can be modified to exhibit different functionalities in the preparation of polymer nanocomposites (PNCs). Graphene is a two-dimensional nanostructured sp2 carbon material with fascinating electronic and mechanical properties derived from its unique structure.3 With a single layer of carbon atoms forming a hexagonal lattice, graphene shows excellent mechanical, electronic, and thermal properties.4

Figure 1. Electrodes / Cyclic Voltammetry curves / Galvanostatic charge-discharge curves of PAni-based hydrogel (A / B / C), GO-PAni-based hydrogel (D / E / F), and rGO-PAni-based hydrogel (G / H / I). In this study, graphene oxide (GO) and reduced graphene oxide (rGO) are explored as nano-fillers with PANI to obtain GO/PANI and rGO/PANI hydrogels. The characterisation of the obtained hydrogels is performed using cyclic voltammetry and galvanostatic charge/discharge studies to evaluate the hydrogel specific capacitance. The use of GO/PANI and rGO/PANI hydrogels in supercapacitors is investigated, and the production of soft 3D electrode architectures for use in soft robotics is explored. References 1.

Stejskal. Conducting polymer hydrogels. Chemical Papers. 71, 1-23 (2017).

2.

Mawad et al. Conductive Polymer Hydrogels. Polymeric hydrogels as smart biomaterials. 9, 19-44 (2016).

3.

Yin, et al. Assembly of Graphene Sheets into Hierarchical Structures for HighPerformance Energy Storage. Acs Nano 5, 3831-3838 (2011).

4.

Cong, et al. Macroscopic Multifunctional Graphene-Based Hydrogels and Aerogels by a Metal Ion Induced. Acs Nano 3, 2693-2703 (2012).

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Electroactive amphiphiles for functional templated gels E.J. Townsend1, A.M. Seddon2 and C.F.J. Faul3 1

Bristol Centre for Functional Nanomaterials, University of Bristol, BS8 1TL 2 School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK 3 School of Physics, University of Bristol, Bristol, BS8 1TL, UK

Poly(aniline) (PANI) is a conjugated polymer which can exist in three distinct oxidation states. A fourth conducting state can be accessed either by oxidative or acid doping, with highest recorded measurements on the order of 103 S/cm.1 Tetra(aniline) (TANI) is an oligomer of PANI which exhibits the same redox and conductive properties, as well as being more soluble in common solvents and easier to process. Recently, a TANI-based cationic amphiphile (TANIPTAB), which forms nanowires in aqueous media, has been prepared.2 When doped with camphorsulfonic acid, the nanowires exhibited conductivity around 2.7 mS/cm. Monoolein is a lipid which can form 3D cubic phases with networks of water channels and has been used to template inorganic and organic materials.3–5 It may be possible to use this as a template to further align the nanowires, facilitating the charge transfer and improving the conductivity.

Figure 1. Left: SAXS plots for monoolein (red) and monoolein/TANI-PTAB (1 mM). Right: Structures of TANI-PTAB and MATANI-PTAB.

In this study, a TANI surfactant (TANI-PTAB) has been synthesised and incorporated into 3D cubic phases formed by monoolein. Small-angle X-ray scattering revealed that the addition of the surfactant did not disturb the lipid phase, as shown in Figure 1. UV-Vis spectroscopy analyses showed it could be doped by addition of an acid. Further experiments are being undertaken to prepare an asymmetric TANI-surfactant with a polymerizable group (MATANI-PTAB) to allow the structure to be fixed before removal of the template and further characterisation (eg. TEM, SEM, AFM). References 1.

Lee, K. et al. Metallic transport in polyaniline. Nature 441, 65–68 (2006).

2.

Bell, O. A. et al. Self-assembly of a functional oligo(aniline)-based amphiphile into helical conductive nanowires. J. Am. Chem. Soc. 137, 14288–14294 (2015).

3.

Seddon, A. M., Lotze, G., Plivelic, T. S. & Squires, A. M. A highly oriented cubic phase formed by lipids under shear. J. Am. Chem. Soc. 133, 13860–13863 (2011).

4.

Bennett, N. et al. Mesoporous tertiary oxides via a novel amphiphilic approach. APL Mater. 4, (2016).

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Nanoscale Homing Vectors for Regenerative Engineering C. L. Hicks1 1

Cellular and Molecular Medicine, University of Bristol, Bristol

Despite the continual improvements in treatments and outcomes following myocardial infarction (MI), cardiovascular diseases (CVDs) remain the leading cause of death worldwide. Current treatments of cardiac ischemia involve perfusion, delivery of blood to the heart, and prevention of further scar formation. More recently, stem cell therapies have been investigated for the replacement and restoration of damaged cardiac tissue. Whilst these studies have shown promising results, new evidence has emerged which suggests stem cells themselves do not persist at the damaged site for very long, and instead myocardial repair is stimulated by the paracrine factors secreted by stem cells, such as extracellular vesicles1. It has been demonstrated that through rational design of a polymer surfactant corona on the surface of a fluorescent protein, nanoconstructs are able to insert into the lipid bilayer of human mesenchymal stem cells (hMSCs), without compromising the structure or function of both the protein and cells. In the present study, we look to apply this new technology towards cell-free therapies, with the construction of surface-modified vesicles for in vivo cardiovascular regenerative medicine. Here, the incorporation of a bacterial protein into the nanoconstructs will allow the vesicles to recognise, and be directed towards damaged cardiac tissue. For initial studies, giant unilamella vesicles (GUVs) will be used as their large size makes them suitable for facile assessment of nanoconstruct insertion efficiency via fluorescence microscopy. Future work will involve applying this vesicle-labelling homing methodology to exosome-based therapies. Exosomes are extracellular vesicles that possess unique biological activity, and have been shown to promote angiogenesis and improve blood-flow to damaged cardiac tissue in mice and large animals with both acute and chronic heart disease2. By combining these properties with the aforementioned homing ability, the modified exosomes could have a serious impact in regenerative engineering.

References (1)

De Jong, O. G.; Van Balkom, B. W. M.; Schiffelers, R. M.; Bouten, C. V. C.; Verhaar, M. C. Front. Immunol. 2014, 5, 608.

(2)

Beltrami, C.; Besnier, M.; Shantikumar, S.; Shearn, A.; Rajakaruna, C.; Laftah, A.; Sessa, F.; Spinetti, G.; Petretto, E.; Angelini, G. Mol. Ther. 2017, 25 (3), 679–693.

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A Novel Bactericidal Titanium Surface to Combat Biofilm Associated Infections of Orthopaedic Implants J. Jenkins1, A. Nobbs1, P. Verkade2 B. Su1 School of Oral and Dental Sciences1 & School of Biochemistry, Wolfson Bioimaging Facility2 University of Bristol, Bristol, UK Prosthetic Joint Infections (PJIs) are a well-documented complication following orthopaedic surgery, with a national average between 1 - 4% in the UK. Although incidence is relatively low, the financial burden associated with revising infected joints is extremely high, reaching £70,000 per patient in cases. The impact of PJIs on the NHS is set to rise as an increasing number of patients are referred to orthopaedic care annually and as antimicrobial resistance continues to emergence. With this in mind, it is important to explore alternative approaches to prevent biofilm formation on titanium medical implants. A possible solution to prevent biofilm formation could be found by designing implant surfaces with bactericidal nanotopograhies. This concept has been inspired by surfaces in nature, such as the Cicada and Dragonfly wing which have evolved nanostructures (NS) that kill bacteria upon contact. In this study, a thermal oxidation technique was employed to generate bioinspired and biomimetic titanium dioxide (TiO2) NS on medical grade titanium alloy (Ti-6Al-4V). To advance our understanding of how contact killing occurs, the Gram negative pathogen Klebsiella pneumoniae was incubated on TiO2 NS surfaces. A combination of bacterial viability assays and electron microscopy techniques were used to investigate the integrity of bacterial cells. Scanning Electron Microscopy (SEM) analysis identified multiple indentations across the envelope of K. pneumoniae cells, these regions were observed at points where NS contacted the envelope. Observations made under Transmission Electron microscope (TEM) confirmed that TiO2 NS can puncture the bacterial envelope. These results illustrate the potential of thermal oxidation as a novel approach to generating bactericidal nanotopographies on titanium. The ability of these surfaces to physically rupture and kill K. pneumoniae upon attachment could prove an invaluable alternative to chemical treatment methods that are prone to bacterial resistance. Bandara, C.D. et al., 2017. Bactericidal Effects of Natural Nanotopography of Dragonfly Wing on Escherichia coli. Briggs, T.W., 2011. Improving the Quality of Orthopaedic Care within the National Health Service in England.

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Nanotechnology in Materials and Construction Jonathan Eales Department of Mechanical Engineering Sciences, University of Surrey e-mail: [email protected] Material selection is crucial to all facets of engineering. The suitability of different materials is determined by a range of factors including their durability and tensile properties. The understanding and subsequent integration of nanotechnology has enabled existing materials to develop far superior properties, both in increasing functionality and by improving sustainability and anti-pollution. Nanotechnology has therefore become an integral part of construction, civil and mechanical engineering. Important applications of nanomaterials in construction include the development of self-cleaning structures and the introduction of nanoparticles in cement1. In response to the threat posed by global warming, a great emphasis has been placed in decreasing the energy consumption of our construction industry and modern infrastructure. Nanotechnology has great potential in aiding this endeavour by developing innovative insulation and cooling systems2. In addition, nanotechnology has already shown great promise in enhancing the performance of renewable energy sources such as solar panels. Despite the benefits there are several possible hazards associated with nanomaterials, such as the toxicity of nanoparticles1. Further investigation and research is required to better understand this issue. In this work we report on diversity of applications that nanomaterials can impact and the challenges they must overcome. Further research into these topics could substantially improve the quality of construction and have a profound effect on our ability to combat global warming and conserve the environment for future generations. References 1.

Pacheco-Torgal, F. & Jalali, S. Nanotechnology: Advantages and drawbacks in the field of construction and building materials. Constr. Build. Mater. 25, 582–590 (2011).

2.

Hanus, M. J. & Harris, A. T. Nanotechnology innovations for the construction industry. Prog. Mater. Sci. 58, 1056–1102 (2013).

68

A prototissue model formed from inorganic protocells embedded in a hydrogel 1

J.Sparks1, Dr M.Li1 and Professor S.Mann1 School of Chemistry, University of Bristol, Bristol

One of the aims of synthetic biology is to recreate living systems by using bottom up approaches to create artificial cells (also known as protocells).1,2 Protocell models aid in understanding cell structure and functions in the origin of life, but are also interesting systems in the fields of drug delivery, material science and as microbioreactors. Several different protocell models have been developed.1 This work focuses on colloidosomes, protocells formed using silica nanoparticle stabilised Pickering emulsions.2 Many in the field are beginning to focus on the collective behaviour of protocells, for example by the assembly of protocell communities into primitive tissue models or protoissues.3 Like real tissues, prototissues exhibit emergent properties due to the communication and cooperation between cells.3 Prototissues can be used as living tissue mimics or be exploited as more complex systems of microbioreactors or functional materials than individual protocells. Stimuli responsive protocells aggregated into prototissues could form interesting stimuli responsive materials or soft devices Herein, we report the development of the first prototissue model based on the trapping of inorganic protocells in an agarose hydrogel, where the hydrogel acts as a mimic of the extra cellular matrix. Communication between protocells through the gel matrix is achieved and utilised in working towards emergent properties. We investigated the material properties of the prototissue and developed its use as possible biocomputing system or bioreactor. Figure 1. 3D reconstruction confocal image (left) and scanning electron micrograph (right) of colloidosome protocells embedded in agarose gel to form a prototissue.

References 1. Li, M., Huang, X., Tang, T.-Y. D. & Mann, S. Synthetic cellularity based on non-lipid micro-compartments and protocell models. Curr. Opin. Chem. Biol. 22, 1–11 (2014). 2. Li, M., Green, D. C., Anderson, J. L. R., Binks, B. P. & Mann, S. In vitro gene expression and enzyme catalysis in bio-inorganic protocells. Chem. Sci. 2, 1739 (2011). 3. Mantri, S. & Sapra, K. T. Evolving protocells to prototissues : rational design of a missing link. Biochem. Soc. Trans. 1159–1165 (2013).

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Solvent-free liquid proteases Jonathan H. Furze(1), Adam W. Perriman(2), and Stephen Mann(1) (1)

School of Chemistry

(2)

Faculty of Biomedical Sciences

The solvent-free liquid protein synthesis [1] has been shown to significantly increase the thermal stability of a protein[2] whilst retaining native-like bio-functionality[3] and backbone dynamics[4] despite lacking the required water molecules to form a hydration sphere. Here, we present an in-depth study of the first solvent-free liquid protease and liquid protein substrate (BSA). Specifically, we report on the structures and activities of the solvent-free liquids of proteinase K (PK) and bovine serum albumin (BSA) and their respective aqueous precursors. We demonstrate that protein cationization and subsequent electrostatic addition of an anionic surfactant does not significantly alter the secondary structure of the proteins, although these surface modifications do reduce the rate of proteolytic activity, to ≈10% and ≈1% respectively. This inhibition is rationalised by the increased charge repulsions and steric hindrance between the protease and the BSA. Significantly, we demonstrate protease activity in a solvent-free environment, although at significantly reduced rate, which can be attributed to diffusion restriction by the high viscosity of the polymer melt environment. References [1] Perriman, A. W.; et al, Solvent-Free Protein Liquids and Liquid Crystals. Angewandte Chemie-International Edition 2009, 48 (34), 6242-6246; [2] Brogan, A. P. S.; et al, Hyper-thermal stability and unprecedented re-folding of solventfree liquid myoglobin. Chemical Science 2012, 3 (6), 1839-1846; [3] Brogan, A. P. S.; et al, Enzyme activity in liquid lipase melts as a step towards solventfree biology at 150 degrees C. Nature Communications 2014, 5; [4] Gallat, F.-X.; et al, A Polymer Surfactant Corona Dynamically Replaces Water in Solvent-Free Protein Liquids and Ensures Macromolecular Flexibility and Activity. Journal of the American Chemical Society 2012, 134 (32), 13168-13171;

70 Fundamentals of Nanotoxicity: Interactions between Nanoparticles and Cell Membranes Laura J. Fox1*, Rob M. Richardson2 and Wuge H. Briscoe3 1

Bristol Centre for Functional Nanomaterials, School of Chemistry, University of Bristol, Bristol, England *[email protected] 2 School of Physics, University of Bristol, Bristol, England 3 School of Chemistry, University of Bristol, Bristol, England

Nanoparticles are widely found in modern technologies, ranging from energy conversion to medical applications 1. However, the cytotoxic effects of nanoparticles are not well understood, stimulating a new research area dubbed ‘nanotoxicity’. Nanotoxicity has been found to depend upon the size, shape and surface chemistry of nanoparticles, and can be imparted via a multitude of toxicity pathways 2. The most common method for determining the cytotoxic effects of nanoparticles has been through dye-based cytotoxicity assays that can provide information such as cell proliferation, glucose consumption and membrane permeability 3. However, these assays give little information about the fundamental interactions between nanoparticles and cells that lead to cellular entry (endocytosis) and resulting toxicity. An understanding of nanoparticle interactions with membranes is key to understanding endocytosis, membrane fusion and nanotoxicity, as well as improving drug-deliveryvector design. Due to the complex nature of cells, this is difficult to examine in vitro and so using membrane models represents a promising and important alternative approach. This project aims to explore how the physicochemical properties of nanoparticles influence their interactions with various membrane models. Many self-assembled lipid systems have been used previously to model cell membranes, including bilayers, monolayers, and liposomes (or vesicles) 4. Whilst lipid multilayers have also long been recognised as bearing structural resemblance to cell membranes, they are conventionally prepared by using spincasting from a volatile organic solvent 5, and thus it has been difficult to study the interactions between such lipid multilayers with biomedically relevant nanoparticles often dispersed in aqueous media. We have recently developed a method for preparation of lipid multilayers via dropcasting aqueous DOPC (a common eukaryotic membrane lipid) liposome dispersions on mica substrates that have been characterised using synchrotron X-ray reflectivity (XRR) at the ESRF in Grenoble 6. So far, we have investigated how polyamidoamine (PAMAM) dendritic nanoparticles (dendrimers) of varying size (or generation) and dosage, functionalised with hydrophobic chains, influence d-spacing, coherence length (La) and paracrystalline disorder (g) in DOPC lipid multilayers. Interestingly, multilayer structural disorder is promoted not only by the dendrimer size, but also by the method of dendrimer addition in liposome preparation. This is evident from the shift in the Bragg peak positions, ΔQ, as well as the peak broadening (i.e. widening in the peak full width at half maximum). Co-assembly of the dendrimer with the lipids during the early stage of the liposome formation leads to dendrimer intercalation in the ultimate stacked lipid bilayers, currently being modelled using Parratt’s method 7.

1. 2. 3. 4. 5. 6. 7.

Beddoes, C. M.; Case, C. P.; Briscoe, W. H. Advances in Colloid and Interface Science 2015, 218, 48-68. Mao, Z.; Zhou, X.; Gao, C. Biomaterials Science 2013, 1, (9), 896-911. Mukherjee, S. P.; Lyng, F. M.; Garcia, A.; Davoren, M.; Byrne, H. J. Toxicology and Applied Pharmacology 2010, 248, (3), 259-68. Rascol, E.; Devoisselle, J. M.; Chopineau, J. Nanoscale 2016, 8, (9), 4780-98. Perino-Gallice, L.; Fragneto, G.; Mennicke, U.; Salditt, T.; Rieutord, F. The European Physical Journal E 2002, 8, (3), 275-82. Sironi, B.; Snow, T.; Redeker, C.; Slastanova, A.; Bikondoa, O.; Arnold, T.; Klein, J.; Briscoe, W. H. Soft Matter 2016, 12, (17), 3877-87. Als-Nielsen, J.; McMorrow, D., Elements of modern X-ray physics. Wiley: New York, 2001; p xi, 318 p.

71

Self-Assembly in Non-Aqueous Green Solvents L. Matthews1,2, R. Sochon3, P. Bartlett2, and W. H. Briscoe2 1

Bristol Centre for Functional Nanomaterials, University of Bristol, Bristol 2 School of Chemistry, University of Bristol, Bristol 3 GlaxoSmithKline, St George’s Avenue, Weybridge, Surrey, KT13 0DE

Non-aqueous solvents are widely used in place of aqueous media in many applications due to their availability, low toxicity and low cost, as well as other physical properties (e.g. viscosity and solvency) that are desirable in manufacturing processes1. Glycerol is one such green solvent, produced as a waste product in the bio-esterification of biodiesel2, allowing for glycerol to be a cheap and available solvent, comparable to water. Molecular self-assembly, which has been widely studied in aqueous and nonpolar solvents, is not well understood in polar non-aqueous solvents such as glycerol. Such an understanding is not only important on a fundamental level, but also relevant to product formulations where organisation, complexation and assembly of molecular and particular species play an important role. Glycerol can also form deep eutectic solvents (DES), which typically contain a quaternary ammonium salt and a hydrogen bond donor3, e.g. when combined with choline chloride. The presence of the choline chloride adds further complexity to the intermolecular interactions in molecular self-assembly. DES are becoming more widespread due to some of the benefits they pose over the traditional organic solvents 4, which include biocompatibility, low toxicity and low cost. This work aims to study self-assembly in non-aqueous polar solvents (in particular glycerol) and to evaluate the validity of the theoretical models designed for aqueous self-assembly. The first system to be considered is glyceline (a DES containing glycerol and choline chloride) at different molar ratios with sodium dodecyl sulfate. Initial experiments will involve examining self-assembly of ionic and zwitterionic surfactants at the air-water interface by measuring the surface tension using the Wilhelmy plate and dynamic bubble pressure method. Further investigations of self-assembly of lipids and surfactants in the bulk and at the solid-liquid interface, and formation of structures such as liposomes and lyotropic mesoscopic phases will be pursued using techniques such as polarised light microscopy and X-ray and neutron scattering. The results will allow a critical evaluation of the applicability of self-assembly models in non-aqueous polar solvents such as glycerol and glyceline with hydrogen bonding densities and strengths that are different from water and nonpolar solvents. 1. H. C. Hailes, Org Process Res Dev, 2007, 11, 114-120. 2. Y. L. Gu and F. Jerome, Green Chem, 2010, 12, 1127-1138. 3. A. P. Abbott, D. Boothby, G. Capper, D. L. Davies and R. K. Rasheed, J Am Chem Soc, 2004, 126, 9142-9147. 4. Q. H. Zhang, K. D. Vigier, S. Royer and F. Jerome, Chem Soc Rev, 2012, 41, 7108-7146.

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Imparting structure into hydrogels using acoustic patterning M. Nichols1, B. W. Drinkwater2, A. Barnes3, A. Patil4 and S. Mann4 1

Bristol Centre for Functional Nanomaterials, School of Physics, University of Bristol, Bristol 2

Faculty of Engineering, Queens Building, University of Bristol, Bristol 3 4

School of Physics, University of Bristol, Bristol

School of Chemistry, University of Bristol, Bristol

Construction of ordered materials with interior structures in 3D is essential for the development of new smart materials. Hydrogels are particularly relevant with the potential to tune their chemical and physical properties by choice of components. However, accurate control over organisation within hydrogel networks is limited.1 Recently it was demonstrated that acoustic waves could trap and manipulate populations of coacervate microdroplets into organised patterns.2 Combining this method with a coacervate system capable of undergoing structural transformation into a hydrogel3 presents a method to impart ordered structures into the hydrogel network.

References 1. Texter J., Colloid Polym Sci, 287:313–321(2009) 2. Tian, L. et al. Nat. Commun. 7, 13068 (2016) 3. Kumar, R K et al. Chem. Sci., 7, 5879 (2016)

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Antimicrobial Surfaces Based on Functionalised Nanospikes Marcus Eales1,2, Angela Nobbs2, Wuge Briscoe3 and Bo Su1 1 2

Biomaterials Engineering Group (BioMEG), University of Bristol, Bristol, BS1 2LY, UK Oral Microbiology (Oral and Dental Sciences), University of Bristol, Bristol, BS1 2LY, UK 3 Briscoe Research Group, University of Bristol, Bristol, BS8 1TS, UK

Bacterial infections account for 20 % of premature implant failures resulting in high patient trauma, increased medical costs and an elevated risk of future complications. With escalating implant demand due to rising obesity and ageing populations, together with increasing antimicrobial resistance causing antibiotics to lose their efficacy, it is imperative to develop new strategies to prevent implant infections. Naturally occurring nanopillars on dragonfly, cicada and butterfly wings have been shown to cause bacterial cell death through physical rupturing of the cell envelope. Titanium is widely used in orthopaedic and dental implants due to its favourable mechanical and biocompatible properties. This study investigates the bactericidal efficacy of titanium dioxide nanospikes grown on pure titanium substrates using an alkaline hydrothermal process. Systematic parameter studies in temperature, time duration, volume and molarity of sodium hydroxide revealed TiO2 nanospikes of three different structures. Their growth homogeneity, height, diameter and density were imaged and quantified by SEM optical profilometry and AFM. Crystal structure analysis has been carried out by XRD and TEM. Further AFM investigation of the surface will be carried out by colloid probe and single cell force spectroscopy alongside surface wettability and energy analysis. Ongoing research is being carried out to find alternative methods, to the commonly used by potentially inaccurate and unreliable Live/Dead stain, to quantify the viability of different species of bacteria when adhered to the different surfaces.

1. Diu, T., Faruqui, N., Sjöström, T., Lamarre, B., Jenkinson, H., Su, B. and Ryadnov, M.G. (2014) Cicada-inspired cell-instructive nanopatterned arrays. Scientific reports, 4, p.7122. 2. Tsimbouri, P.M., Fisher, L., Holloway, N., Sjostrom, T., Nobbs, A.H., Meek, R.M.D., Su, B. and Dalby, M.J. (2016) Osteogenic and bactericidal surfaces from hydrothermal titania nanowires on titanium substrates. Scientific Reports, 6(November), p.36857.

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Silk-Bone: Effect of LiBr concentration R. O. Moreno1,2, A. Seddon2 and S. Davis1 1

2

School of Chemistry, University of Bristol, Bristol Department of Physics, University of Bristol, Bristol

The demand for effective bone replacement materials has increased through the years, driven by an aging population1. Most orthopaedic interventions require both bioinert metal implants and bone graft material1–3; the latter is used to secure the implants in place, and to promote proper adhesion, increasing the success rate of the interventions. The mechanical properties of bone are associated with the hierarchical arrangement of nanostructured collagen and hydroxyapatite.4 Whilst many attempts have been made to mimic this structure and composition ,2,5,6most synthetic composites of collagen/hydroxyapatite show poor performance under load. Silk fibroin is a good candidate to replace collagen in these biocomposites, due to its known outstanding mechanical properties and excellent biocompatibility7–9. These materials have already proven useful as cartilage replacements. Previous studies provided proof of concept that cross-linking silk fibroin and mineralizing with calcium phosphate minerals can produce biomaterials with mechanical properties comparable to bone in the dry state10.However, their mechanical properties , in physiological conditions need to be improved to be viable as allograft materials. It is the aim of this project to investigate key steps of the synthesis procedure, aiming to further improve, both, the mechanical properties and clinical application. In this presentation, the effect of the initial concentration of LiBr of the silk fibroin solution is investigated. Once the silk fibroin is extracted from the silkworm cocoons, the LiBr is used to prevent it from folding and gelling11. The effect this parameter has on the mineralization, the folding of the silk fibroin, the microstructure and the mechanical properties of the composite are studied using FTIR, EDX, XRD, SEM and axial compression testing. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Arifin, A. et al. A review. J. Mater. Des. 55, 165–175 (2014). Liao, S. et al. J. Biomed. Mater. Res. 69B, 158–165 (2004). Cao, C. et al. Ceramics International 40, 13987–13993 (2014). Weiner, S. & Wagner, H. D. Annu. Rev. Mater. Sci 28, 271–98 (1998). Zhang, W. et al. Sci. Rep. 5, 11199 (2015). Yunus Basha, R., Sampath, S. K. & Doble, M. Mater. Sci. Eng. C 57, 452–463 (2015). Meinel, L. et al. Bone 37, 688–698 (2005). Melke, J.et al. Acta Biomater. 31, 1–16 (2016). Mottaghitalab, F. et al. J. Control. Release 215, 112–128 (2015). Collins, A. M. et al. Adv. Mater. 21, 75–78 (2009). Sashina, E. et al. J. Appl. Chem. 79, 869–876 (2006).

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Electrolytic Oxygen Generation on Platinum Nanoparticles 1

P. van der Linde1 Mesoscale Chemical Systems, University of Twente, Enschede, The Netherlands

Solar fuels are promising zero CO2 emission candidates to replace fossil fuels. Water splitting driven by sunlight is one of the candidates to produce solar fuels on a large scale. The technique makes use of photo-active electrode materials to absorb photons. The absorbed photons promote electrons from the valence band to the conduction band. This charge separation drives the water splitting reaction that generates hydrogen and oxygen gases by breaking the bonds of water molecules. The formed gases can be used as energy carriers. Catalysts are used to increase the reaction rates and optimize the conversion efficiencies. The water splitting efficiency is reduced by the formation of bubbles on the electrodes. Formed gas bubbles increase the Ohmic resistance of bulk liquid and block the catalytic sites and the electrodes locally for the reaction. Here we aim to create fundamental understanding of how gas is transported at nanosized catalytic sites and understanding about bubble nucleation on such sites. We fabricate a flow cell to study the formation of bubbles and the influence of dissolved oxygen gas in the liquid phase near the electrode surface and catalytic nanoparticles. The nanoparticles are formed on silicon electrodes via photo-assisted electrodeposition of platinum. This method allows for control over the size of the platinum particles and density. To mitigate effects such as light scattering and lensing effects by the bubbles formed in our measurements, we drive the reaction by application of a potential. The oxygen evolution reaction is imaged by fluorescence microscopy. This is achieved by pH sensitive dyes which can change their emission spectra with the local pH changes caused by the evolving oxygen concentration. The gained knowledge of where bubbles form and how they interact with and at the catalytic sites, will be used in designing electrodes for more efficient solar driven water splitting.

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Nitrogen-Containing Porous Organic Materials: Experimental and Computational Approaches P. Boonrod1, C.F.J. Faul2, and N. Fey2 1

Bristol Centre for Functional Nanomaterials, University of Bristol, Bristol, United Kingdom 2

School of Chemistry, University of Bristol, Bristol, United Kingdom

Carbon dioxide, among other gases, is one of the greenhouse gases which accumulates in the atmosphere and causes climate change. Carbon capture and storage (CCS) technology therefore becomes important, and various porous materials have been developed to address this problem.1,2 Nitrogen-containing porous organic materials (NCPOMs) are a group of conjugated microporous polymers (CMPs) that are good candidates for gas adsorption with high affinity toward CO2.3 In this work, both experimental and computational approaches are exploited to begin to propose design rules for NCPOMs to fit the desired applications, such as adsorption of CO2 gas. These materials can be synthesised from Buchwald-Hartwig coupling reaction between cores and linkers, creating arylamine networks as illustrated in Scheme 1. Meanwhile, structural fragments consisting of one core molecule and three linker molecules can be optimised with Density Functional Theory (DFT) methods for both already synthesised materials and those to be synthesised in the future. Experimental characterisation data for synthesised materials can then be combined with calculated parameters to establish structureproperty relationships and so to explain and predict properties of materials prior to synthesis.

Scheme 1. Buchwald-Hartwig coupling reactions to make arylamine frameworks References 1. D’Alessandro D M, Smit B, and Long J R. Angew. Chem. Int. Ed. 49 (2010) 6059 2. Alonso A, Moral-Vico J, Abo Markeb A, Basquets-Fité M, Komilis D, Puntes V, Sánchez A, and Font X. Sci. Total Environ. 595 (2017) 51 3. Liao Y, Weber J, and Faul C F J. Chem. Commun. 50 (2014) 8002

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A nanoparticle coating for titanium exhibiting controlled chlorhexidine release for infection prevention on dental implants S Garner1,2, A Nobbs2, M Barbour1 1 Oral Nanoscience, Bristol Dental School, University of Bristol, Bristol 2 Oral Microbiology, Bristol Dental School, University of Bristol Background Dental implants are an increasingly popular solution to replacing missing teeth; over 1 million are placed annually worldwide1. They are usually manufactured from titanium, which exhibits the property of osseointegration, resulting in a highly resilient bond between implant and bone. In 1.7% of implants2 (4-10% of patients), osseointegration is not achieved, and this is related to competition for colonisation, where oral bacteria outcompete osteoblasts, the cells which carry out the osseointegration process. Failure of the implant to osseointegrate can lead to bone loss and implant failure. This work describes the development of a sparse, homogeneous nanoparticle coating for titanium, which exhibits controlled release of adequate volumes of the antimicrobial chlorhexidine (CHX) to prevent colonisation of a newly placed implant by oral bacteria, whilst still allowing osteoblast colonisation. Methods Titanium substrates were sand blasted and acid etched (SLA) to represent the most common commercial implant surface topography. The substrates were coated with chlorhexidine hexametaphosphate nanoparticles (CHXHMP NPs) produced in a precipitation reaction between sodium hexametaphosphate and chlorhexidine digluconate with 0.5% poloxamer 407 (P407), to reduce aggregation. Surface roughness, contact angle and homogeneity of coating were determined, and chlorhexidine release per unit area was measured using UV spectrophotometry at 255 nm. Results Surface properties of the plain and coated SLA were comparable to those of dental implants in clinical use. Surface roughness of SLA coated with CHXHMP NPs produced with P407 was similar to uncoated SLA (Ra 1.05 µm vs 1.04 µm), and reduced the water contact angle (coated 94.4˚, uncoated 111.3˚). When no P407 was used, surface roughness increased (Ra 1.13 µm) and contact angle remained similar to uncoated SLA (108.4˚). Greater and longer duration CHX release was observed from SLA coated with CHXHMP NPs (260 µmoles/m2 at 30 days) versus a CHXHMP NP coating produced with P407 (19 µmoles/m2), but both released more than SLA coated with aqueous CHX (4 µmoles/m2). Conclusions A CHX releasing nanoparticle coating for titanium has potential in the prevention of immediate colonisation of the implant surface by microbes after surgical placement. The coatings exhibit surface properties comparable to implant surfaces already in use, and the prolonged CHX release could be particularly beneficial during the osseointegration process. Future work will establish the antimicrobial efficacy of this coating versus relevant oral bacteria, and its biocompatibility with osteoblasts.

1. 2.

References Global Business Intelligence. GBI Dental Implants Market to 2018. (2013). Camps-Font, O., Figueiredo, R., Valmaseda-Castellón, E. & Gay-Escoda, C. Postoperative Infections After Dental Implant Placement. Implant Dentistry 24, 1 (2015).

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Smart glyco-nanomaterials as novel anti-cancer drug delivery systems. Sadiyah Sheikh*, a Dr. M. Carmen Galan, b Dr. Henkjan Gersen, b Dr. Monica Berry. a School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS. b School of Physics, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL. *[email protected] Abstract The development of drug delivery systems that can target specific cell lines is of the utmost importance to improve cancer cell targeting for treatment [1]. Cell surface carbohydrates are involved in a myriad of biological processes relevant to both healthy and disease mechanisms which can be exploited for targeting. Our group has shown that glycans conjugated to a nanoparticle can be used to modulate intracellular uptake and localization [2]. More recently, we have reported the synthesis of a novel class of carbon-based fluorescent nanomaterials. These fluorescent nanoparticles are water soluble and can be easily functionalised with a given biomolecule as well as being non-toxic to cells [3]. Herein we report the synthesis and characterization of functionalised carbon dots (Cdots) for use as imaging probes. A series of glycans and lectins were conjugated to the CDots and their physico-chemical properties analysed by Z-potential, DLS, NMR, TEM, SAXS and AFM to gain a better understanding of the structure of the complex and 3D presentation of the biomolecules. The different CDot conjugates were then assayed in a panel of cancer cell lines and their intracellular uptake and toxicity profile evaluated. This work has applications in early cancer diagnostics. Key words: carbon dots, drug delivery, lectin interactions, FRET 1. Xiaojuan, W.; Xing, S.; Jun, L.; Hua, H.; Tiantian, C.; Mingqing, W.; Shengjie, W.; Fang, H. Colloids and Surfaces B: Biointerfaces 2014, 122, 638-644 2. Benito-Alifonso, D.; Tremel, S.; Hou, B.; Lockyear, H.; Mantell, J.; Fermin, D. J.; Verkade, P.; Berry, M.; Galan, M. C. Angewandte Chemie 2014, 53, 810. 3. Hill, S; Benito-Alifonso, D.; Morgan, D; Davis, S; Berry, M; and Galan, M. C. Nanoscale 2016, 8, 18630-18634

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Two-Dimensional Functional Nanostructures Through the Self-Assembly of ChargeTerminated Crystallisable Homopolymers Samuel Pearce1,2, Xiaoming He3, Ian Manners2 1

Bristol Centre for Functional Nanomaterials, HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, BS8 1TL, United Kingdom 2 School of Chemistry, University of Bristol, Cantocks Close, Bristol, BS8 1TS, United Kingdom 3 School of Chemical Science and Engineering, Tongji University, 1239 Siping Rd., Shanghai, China

Two-dimensional (2D) nanostructures, such as graphene, clay nanoplatelets, and metal chalcogenide nanosheets are of interest in a broad range of applications from composite reinforcement to photovoltaics. However, the creation of 2D materials from soft matter by selfassembly represents a substantial challenge. Block copolymers (BCPs) with a crystallisable segment undergo living crystallisation-driven self-assembly (CDSA), resulting in BCP micelle fibres of controlled length and low polydispersity. Amphiphilic 1D BCP micelles have allowed access to complex superstructures, such as “windmill” supermicelles and large micelle superlattices. Processes that allow the formation of 2D nanoplatelets of controlled dimensions and with various compositions by living CDSA, include the use of BCP/homopolymer blends1 and charge-terminated semi-crystalline homopolymers.2 Extension of these methods are currently under investigation, as are the potential applications of the resulting 2D nanomaterials.

Figure 1- Scheme depicting the formation of ribbon-like 2D platelets, with a TEM image displaying the structure and a graph displaying the area dependence on polymer added to seed initiator. References (1)

Qiu, H.; Gao, Y.; Boott, C. E.; Gould, O.; Harniman, R. L.; Richardson, R. M.; Miles, M. J.; Manners, I. Science, 2016, 352, 697.

(2) He, X.; Hsiao, M.-S.; Boott, C. E.; Harniman, R. L.; Nazemi, A.; Li, X.; Winnik, M. A.; Manners, I. Nat Mater, 2017, 16, 481

80

Control and characterisation of the polymorphism and morphology of Indomethacin.

V. Hamilton12, S.R. Hall1 & S. Davis1 1

School of Chemistry, University of Bristol, Bristol Bristol, Bristol

2

School of Physics, University of

More than 50% of all active pharmaceutical ingredients (APIs) demonstrate polymorphism, taking on different crystalline structures or molecular conformations1. This structural change strongly impacts the physio-chemical properties of the API, which can subsequently affect the pharmaceutical’s key properties, including stability, solubility and bioavailability. New polymorphs may offer more favourable properties or even allow previously unviable APIs to be bought to market. Controlling polymorphism is one of the leading issues in the pharmaceutical industry. Indomethacin (IMC) is a common, non-steroidal anti-inflammatory API. IMC is highly polymorphic with 5 known polymorphs and forms many solvates2. In the current work, the growth and characterization of the different polymorphs of IMC are explored. Only two of IMCs polymorphs have known crystalline structures, the aim beyond the current work is to solve the remaining polymorphs “ab inito” using 3D electron tomography3. The project also extends to the prospect of controlling the polymorphism of IMC with magnetic fields, following the discovery of a new polymorph of coronene under field4. References 1.

Karpinski, P. H. Polymorphism of active pharmaceutical ingredients. Chem. Eng. Technol. 29, 233–237 (2006).

2.

Surwase, S. A. et al. Indomethacin: New polymorphs of an old drug. Mol. Pharm. 10, 4472–4480 (2013).

3.

Mugnaioli, E., Gorelik, T. & Kolb, U. ‘Ab initio’ structure solution from electron diffraction data obtained by a combination of automated diffraction tomography and precession technique. Ultramicroscopy 109, 758–765 (2009).

4.

Potticary, J. et al. An unforeseen polymorph of coronene by the application of magnetic fields during crystal growth. Nat. Commun. 7, (2016).

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Role of surfactant concentration, micellar stability and availability of monomers in tuning the size of silver nanoparticles

Vidhi Shah1, Bhavesh Bharatiya1, M. K. Mishra1, Atindra Shukla1, Dinesh. O. Shah1,2,3 1

Shah-Schulman Center for Surface Science and Nanotechnology, Dharmsinh Desai University, Nadiad-387001, Gujarat, India

2

Center for Surface Science and Engineering, Department of Chemical Engineering and Department of Anesthesiology, University of Florida, Gainesville, Florida 32611, USA

3

College of Earth and Environmental Sciences Columbia University, New York, NY 10027, USA [email protected]

Abstract: A typically favourable condition controlling the size of silver nanoparticles (AgNPs) in aqueous sodium dodecyl sulphate (SDS) solutions in presence of Tri-Sodium Citrate (TSC) was investigated by various analytical techniques. The role of SDS as stabilizing agent is investigated in relation to a molecular mechanism, presumably leading to an effective size control and narrow size distribution. Under experimental conditions, the smallest size AgNPs were synthesized for reaction mixtures containing 35 mM SDS. As investigated by PTFE wettability and dynamic surface tension experiments, the role of peculiar SDS concentration in observed size control of AgNPs is attributed to formation of stable mixed aggregates at the given condition and accordingly reduced numbers of free SDS monomers diffusing to the growing AgNP interface. The formation and further growth of AgNPs at the micellar interface is proposed, which is controlled by proposed stable aggregates of SDS:TSC. The smallest size of AgNPs was also confirmed by TEM images, which illustrates mixed morphologies for the nanoparticles in an aggregated state. The NMR experiments reveal strong hydrophobic interactions between the alkyl chains of SDS molecules during the reduction process. These results also indicate that TSC remain in bulk phase without solubilizing in the SDS aggregates. A plausible molecular mechanism is proposed based on the supply of Ag+ ions at the growing AgNP surface by the SDS monomers and submicellar aggregates resulting in formation of bigger size AgNPs. A peculiar size control for AgNP in presence of 35mM SDS is presumably driven by the capping of stable SDS micelles around growing nuclei and restricted number of SDS monomers and submicellar aggregates responsible for supply of Ag+ at the growing AgNP nuclei.

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Synthesis of pH-Sensitive cationic phosphonium AuNPs in aqueous medium Wanisa Abdussalam-Mohammed and Yon Ju-Nam College of Engineering, Swansea Univeristy, Swansea, United Kingdom. E-mail: [email protected] INTRODUCTION Nano-therapeutics is a rapidly progressing area of research and aims to improve therapeutic efficacy with minimal side effects by the selective augmentation of anticancer drug concentrations within tumour tissues thus solving the problems presented by conventional chemotherapy. The main goal of this study describes the further development of phosphonioalkyl ligands to use in functionalised AuNPs. The AuNPs were functionalised with ligands including triphenylphosphoniopropylthiosulfate (4a, b), tri(P-tolyl)-(3-thioacetylpropyl)-phosphonium bromide (5a) and tris(2,4,6-trimethoxyphenyl)(3-thioacetylpropyl)-phosphonium bromide (5b). The functionalised AuNPs were subjected to investigate their stability over time at a pH range of 3-11. AuNPs were primarily characterised by UVVis spectroscopy, (TEM) and (DLS). While, the ligands were characterised by (ATR), (ESIMS) and (NMR). The AuNPs syntheses were conducted in one of two ways with reduction by a biphasic solvent system of DCM / H2O, and monophasic medium DMSO 1.

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Photodynamic Antimicrobial TiO2 Nanosurfaces under Visible Light Xue Dong1 and Bo Su2 1

Bristol Center for Functional Nanomaterials, University of Bristol, Bristol 2

Biomaterials Engineering Group, University of Bristol, Bristol

Abstract: By doping metal to narrow the band gap of anatase titanium oxide (TiO2) is one of the pathway to activate its photocatalytic performance within visible light. With hydrothermal method, the band gap decreases from 3.4eV to 2.4eV in average without the destruction of the nanowires morphology, and doped one performs a better photocatalytic than undoped TiO2 nanowires. Introduction:TiO2 has photocatalytic effect under UV which can be applied for disinfection materials and water treatment. Interestingly, TiO2 nanowires perform a better endurance and efficiency in comparison with particles1. However, only stimulated under UV limits its application, so efforts also put on doping metals to reduce its wide band gap (3.2eV). The same method - hydrothermal method has been used to produce TiO2 nanowires and dope metals. Unfortunately, only Fe doping works compared with Cu and Sr. Moreover,the bleaching of the organic dye p-nitrosodimethylaniline(RNO) is chosen to test the photocatalytic effect. Method: Hydrothemal method2 Result: It turns out that Cu and Sr cannot dope into TiO2 nanowires by this method and only Fe works, decreasing from 3.4eV to 2.4eV in terms of band gap when the concentration is 0.09 mol/L. The images taken from SEM prove that the morphology does not change in comparison with undoped nanowies. Moreover, a relative reduction of RNO concentration has been tested by UV-VIS spectroscopy which demonstrates doped TiO2 nanowires perform a better photocatalytic effeciency.

Reference 1. Tian Y, Xu M, Liu X, et al. Preparation and Photocatalytic Properties of Titania Nanowire Arrays with Shape of String of Candied Haws[J]. Chinese Journal of Catalysis, 2006, 27(8): 703. 2. Liu B, Boercker J E, Aydil E S. Oriented single crystalline titanium dioxide nanowires[J]. Nanotechnology, 2008, 19(50): 505604.

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Improving the medium to high temperature performance of platinum microheaters Yiyuan Zhao Micro Sensors and Systems Group, University of Twente, Netherlands In many microscale sensor applications, such as thermal flow sensors and microheaters in the microfluidic reactors, platinum thin films are widely used to heat the microfluidic channels as well as sense the fluids temperature with high accuracy. However, being subject to the biased voltage over long period of times, usually once reaching the medium to high operation temperatures above 500℃, platinum thin films suffer from poor adhesion from the silicon based substrates. Eventually, platinum would peel off from the substrate and the heat transfer to the surrounding substrate becomes rather poor, platinum thin films start to overheat and breakup. In our microscale methane combustor chip, we encounter the poor adhesion problem of platinum heaters at around 600℃. In this study, several considerations are introduced and summarized to achieve medium to high temperature compatible platinum microheater to preheat the combustor chamber to the methane self-ignition temperature of 600℃. Thin film electromigration and degradation at elevated temperatures are the two main aspects when considering to maintain good mechanical and electrical performances of the platinum microheaters. In the electromigration considerations, [1] two dominant factors include working below the maximum allowed current density limit, and using AC bias voltage with a certain frequency instead of DC current can improve the Mean Time to Failure of a platinum thin film. This can avoid the formation of hillocks and voids, hence the shortcut or breakage of the platinum wires respectively. Special care has to be taken at the wire corners due to the geometric effects on the current density. In the high temperature performance aspect, good adhesion materials at high temperature such as tantalum is a better choice over titanium. [2] An encapsulation layer over the platinum heater thin film would also help to suppress the material diffusion and maintain better adhesion. [3] Moreover, annealing in advance would help to relax the as-deposited stress and defects to improve against the thin film delamination. Experiments with the electrical properties such as resistivity and Temperature Coefficient of Resistance of platinum at medium to high temperatures would give a more realistic prediction of the required power supply to achieve the target temperature. References 1. Lienig, J., introduction to electromigration-aware physical design, in Proceedings of the 2006 international symposium on Physical design. 2006, ACM: San Jose, California, USA. p. 39-46. 2. Tiggelaar, R.M., et al., Stability of thin platinum films implemented in hightemperature microdevices. Sensors and Actuators A: Physical, 2009. 152(1): p. 39-47. 3. Lisker, M., et al., Effect of annealing in oxygen atmosphere on morphological and electrical properties of iridium and ruthenium thin films prepared by liquid delivery MOCVD. Surface and Coatings Technology, 2007. 201(22): p. 9294-9298.