Synthesis of Streptomycin Conjugated Silver Nanoparticles using Azadirachta indica (neem) Leaf Extract and their Antimicrobial Potency of against Multidrug Resistant Staphylococcus aureus

The emergence of multidrug resistant (MDR) pathogenic microbes against typical antibiotics is a global problem. Novel and effective strategies are being employed to treat various disease causing MDR pathogens. In this direction, we prepared silver nanoparticles (AgNPs) conjugated to streptomycin which exhibited significantly enhanced antibacterial effect against MDR Staphylococcus aureus. The aqueous Azadirachta indica (Neem) leaf extract was used for the synthesis of AgNPs and Streptomycin conjugated silver nanoparticles (St-AgNPs). The synthesized nanoparticles were characterized by different analytical techniques to establish the formation, size, shape and the presence of functional groups. The antimicrobial activity of AgNPs and St-AgNPs was examined by using the agar-well plate method against MDR Staphylococcus aureus. The UV-visible spectra indicating absorbance at 450 and 440nm confirmed the formation of AgNPs and St-AgNPs, respectively. The scanning electron microscopic images showed that nanoparticles are spherical in shape and the size in the range of 21- 30nm and 29 - 43nm, respectively. The X-ray diffraction pattern of AgNPs and St-AgNPs showed peaks establishing the crystalline nature of the particles with characteristic peaks of 2θ for (111), (200), (220) and (311) planes. The FTIR spectrum of synthesized AgNPs and St-AgNPs showed typical absorption peaks corresponding to the groups present in both AgNPs and streptomycin. The analysis of antimicrobial activity against MDR S. aureus indicated that St-AgNPs exhibited ~50% higher activity as compared to streptomycin alone. Further detailed studies are in progress to confirm the utility of antibiotic conjugated AgNPs.