Abstract

Development of biologically inspired experimental processes for the biosynthesis of nanoparticles (NPs) is an evolving important branch of nanotechnology. In the present work, we studied the potential of four bacterial species for extracellular production of nanosilver (AgNPs) from 3 mM concentration of silver nitrate (AgNO3) after incubation for 4h at 85°C. Biosynthesized AgNPs were characterized by using different methods such as; UV/vis spectroscopy, Transmission electron microscope (TEM), X-Ray Diffraction (XRD) and Fourier Transform Infra-red (FTIR) spectroscopy. Results of UV–vis spectroscopy showed maximum absorption at 401-432 nm, which represents the characteristic surface plasmon resonance of AgNPs. TEM demonstrated that the size range of these NPs ranged approximately from 7.8- 13.4 nm. Representing the XRD pattern obtained for the AgNPs, a number of Fcc structures of silver Bragg reflections corresponding to (100), (110), (111), (200) and (220) planes were observed. FTIR results recorded a downward shift of absorption bands between 400–4000 cm −1 indicating the formation of AgNPs. Finally we concluded that the extracellular biosynthesis of AgNPs by the four bacterial species; Ochrobactrum sp. (MAM-C9), Achromobacter xylosoxidans (MAM-29), Pseusomonas aeruginosa (MAM-42) and Bacillus cereus (MAM-I.11) were confirmed. This study recorded that bacterial biosynthesis of AgNPs is useful to avoid adverse effects of chemical and physical methods that are non-suitable for medical applications.

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