Jyothi Hiremath, Vandana Rathod, Shivaraj Ninganagouda, Dattu Singh, K. Prema, Studies on Biosynthesis of Silver Nanoparticles Using Rhizopus sp. and its Antibacterial Efficacy on E. coli MDR Strains, ILNS Volume 23, International Letters of Natural Sciences (Volume 23)
    Nanotechnology is a field that is burgeoning day by day, making an impact in all spheres of human life. Biological methods of synthesis have paved way for the “greener synthesis” of nanoparticles and these have proven to be better methods due to slower kinetics, they offer better manipulation and control over crystal growth and their stabilization. In this context we have investigated extracellular biosynthesis of silver nanoparticles (AgNP<sub>s</sub>) using cell-free extract of<i> Rhizopus spp</i>.. Formation of AgNP<sub>s</sub> was indicated by the change in the colour of the cellfree extract from yellow to dark brown under static condition after 48 hrs of incubation. Characterization of AgNP<sub>s</sub> was carried out by UV-Vis Spectroscopy which gave sharp plasmon resonance peak at 429 nm corresponding to spherical shaped nanoparticles. Transmission electron microscopy (TEM) micrograph showed formation of well-dispersed AgNP<sub>s</sub> in the range of 25-50 nm. Scanning electron microscopy (SEM) showed the particles to be uniformly dispersed without agglomeration with smooth morphology. EDS showed the presence of elemental silver at 3kev. X-ray diffraction (XRD)-spectrum of the AgNP<sub>s</sub> exhibited 2θ¸ values corresponding to nanocrystal. These biosynthesized AgNP<sub>s</sub> were used to study their antimicrobial activity against Multi-drug resistant (MDR)<i> E. coli</i> strains, by Agar diffusion method. Zone of inhibition was measured. Synthesis of nanosized particles with antibacterial properties, which are called "nanoantibiotics", is of great interest in the development of new pharmaceutical products.
    EDS, Multi Drug Resistance (MDR), <i>Rhizopus spp</i>, SEM, Silver Nanoparticles, TEM, XRD