Biosynthesis and characterization of silver nanoparticles using extract

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Ravishankar Bhat1, Sharanabasava V. Ganachari1, Raghunandan Deshpande2, ... Department of Materials Science,Gulbarga University, Gulbarga- 585 106 ...
Inernational Journal of Science Research Volume 01, Issue 04

Biosynthesis and characterization of silver nanoparticles using extract of fungi Acremonium diospyri Ravishankar Bhat1, Sharanabasava V. Ganachari1, Raghunandan Deshpande2, Mahesh D. Bedre1, A. Venkataraman*1 1 Materials Chemistry Laboratory, Department of Materials Science,Gulbarga University, Gulbarga- 585 106 Karnataka, (India) 2 H.K.E.S’s Matoshree Taradevi Rampure Institute of Pharmaceutical Sciences, Sedam Road, Gulbarga 585105, Karnataka, (India) *Author for correspondence, Ph. No.: +91-8472-263295 (O), +91-8472-245995 (R), +91-9880801017 (Mobile), Fax: +91-8472-263206.

e-mail: [email protected]

Abstract: Nanotechnology is gaining remarkable importance in the present century due to its capability of modulating metals into nano form, which changes the chemical, physical and optical properties of metals. The development of techniques for the controlled synthesis of nanoparticles with well-defined size, morphology and composition, to be used in the biomedical application and areas such as optics and electronics, has become a challenge. Development of reliable and eco-friendly processes for synthesis of such metallic nanoparticles has gained significance in recent times. One of the options to attain this objective is to use natural sources such as biological systems. The present study reports the synthesis of silver nanoparticles (AgNPs) through Ag+ ion reduction employing extract of fungi Acremonium diospyri. The nanoparticles obtained are characterized by UV–vis spectroscopy, energy-dispersive spectroscopy (EDX), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). UV-vis results showed characteristic surface plasmon resonance peak at 425nm. EDX study confirmed the presence of elemental silver along with organic moiety. From AFM, FESEM, and TEM study it is observed that particles are irregular in shape and size are approximately 40nms in size. The synthetic method employed in the present study is a simple, cost effective and a green chemistry approach. Keywords: Nanotechnology, Biosynthesis, Silver nanoparticles, Acremonium diospyri, energy-dispersive spectroscopy. 1. INTRODUCTION

2. EXPERIMENTAL

Nanoparticle research is inevitable today not because of only application and also by the way of synthesis [1]. Route of synthesis of nanoparticles by physical and chemical methods may have considerable environmental defect, technically laborious and economically expensive [2]. Currently, there is a growing need to develop a green chemistry approach towards nanoparticle synthesis process that does not use toxic chemicals in the synthesis protocols [3-4]. The secrets gleaned from nature have led to the development of biomimetic approaches to the growth of advanced nanomaterials [5]. Biological synthesis of nanoparticles has gained more attention by the researchers for its potential applications [6-7]. Almost all type of biological entity has been used for the synthesis of nanoparticles with different size and shape [8-12].

2.1 Materials and Methods The fungus culture, Acremonium diospyri (1316T strain) was obtained from IMTEC; Chandigarh, All chemicals used were of analytical grade. Acremonium diospyri was grown in potato dextrose broth (potato starch 4 g/l, dextrose 20g/l). The pH was attuned approximately for inhibition of bacterial growth. The flasks were incubated in the environmental shaker at 200 rpm at 25°C. Silver nitrate AgNO3, 10-3M final concentration was mixed with 50 ml of cell filtrate in a 250 ml Erlenmeyer flask and agitated at 250C in dark. Control (without the silver ion, only biomass) was also run along with the experimental flask. Change in color was observed in the silver nitrate solution incubated with the A. diospyri. 2.2 Characterization

In the present report, we report the synthesis and characterization of silver nanoparticles using fungi Acremonium diospyri, belongs to the Phylum Ascomyta and family Hypocreaceae. Furthermore, this green biogenic approach is cost-effective and simple and can become alternative to chemical synthesis [13].

The formation of AgNP is verified by using UV-vis 5704SS ECIL spectrophotometer operated at 1nm resolution with an optical length of 10 mm. UV-vis analysis of the reaction mixture was observed for a period of 300 sec. For the study of crystallinity, films of colloidal AgNP formed on Si (III) substrates by drop coating were

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Inernational Journal of Science Research Volume 01, Issue 04 preliminary identification of formation of silver nanoparticles [14].

used for X-Ray-diffraction (XRD) study. The data were obtained using Siemens X-Ray diffractrometer (Japan), operated at 30 kV and 20mA current with CuKá (I=1.54Ao).The structural morphology of AgNP formed was examined by using Field Emission Scanning Electron Microscopy (FESEM, FEI Nova nano 600, Netherlands) and these images were operated at 15 KV on 0o tilt position. The Transmission Electron Microscopy (TEM) images were obtained using Technai-20 Philips instrument operated at 190 Kev. Sample for this analysis were prepared by coating the aqueous AgNP on carbon coated copper grids, kept for 5 min; the extra solution was removed using blotting paper. The film of TEM grid is exposed to IR light for drying. The images of Atomic Force Microscope (AFM) were collected under ambient conditions on a Veeco-Innova scanning probe microscope, etched Si – nano probe tips (RTESPA-M) were used for the same

Figure 2: UV-vis spectra of silver nanoparticles showing characteristic surface plasmon peak at 425nm

3. RESULTS AND DISCUSSION The detailed study on biosynthesis of functionalized silver nanoparticles by A.diospyri was carried out. Fig. 1 shows conical flasks containing the filtrate of A.diospyri biomass with silver ions at the beginning and after 24h of the reaction, respectively.

A characteristic surface plasmon peak is observed at 425 nm after 24h of reaction and is shown in Fig.2. The peak at 290nm is because of organic moieties present in the reaction mixture. This observation matches with the results of EDAX were ‘C’ and ‘O’ peak is occurred due to organic moieties as shown in Fig. 3. It is also confirmed from the ‘Ag’ peak that nanoparticles formed are indeed silver nanoparticles and are in crystalline nature. The presence of ‘Al’ peak is occurred due to the aluminum grid used for the EDAX study.

Figure 1: Picture of conical flasks containing the filtarate of Acrremonium diospyri biomass in aqueous solution of 10-3 M AgNO3 at the beginning of the rection (flask 1) and after 24h of reaction (flask 2)

Figure 3 : Energy Dispersive X-Ray spectrum (EDAX) of metallic silver nanoparticles Fig. 4 is AFM 3D image shows irregular shapes of nanoparticles with organic capping. From the AFM results the average height of the nanoparticles are found to be 26nm.

It is observed that color of the solution is changed from colorless to dark reddish brown color and this is

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Inernational Journal of Science Research Volume 01, Issue 04 Furthermore we are trying to determine the complete aspects of proper identification and isolation of compounds that are rresponsible for the reduction and capping of the nanoparticles. 4. ACKNOWLEDGEMENT Authors are grateful to DAE-BRNS Project (No.2009/ 34/14/BRNS), UGC Major Research Project (F: 41-101/ 2012) and VGST (D38-7), Bangalore for financial assistances. Authors thank Prof. G.U. Kulkarni and Mrs.Selvi Rajan JNCASR, Bangalore for providing FESEM facility.

Fig. 4 : AFM 3D image of biofunctionalized Silver nanoparticles.

5. REFERENCES

The FESEM image of silver nanoparticles is shown in Fig.5 on nanometric scale. It can be observed that the surface morphology nanoparticles biosynthesized from A.diospyri biomass clearly indicates that they are irregular in shapes. There are few traces of silver nanoparticles clusters which may contribute for the variation of particle size.

Figure 5: FESEM images of Silver nanoparticles.

Figure 6: TEM images of Silver nanoparticles.

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