Production of Silver Nanoparticles by Escherichia coli: Green Approach

Abstract

Physical and chemical approaches to synthesize nanoparticles are not suitable for safer medical usage. Thus, green method could be a suitable approach to produce safe and non-toxic nanoparticles. In this study, silver nanoparticles were synthesized by Escherichia coli and its biological activities were determined. The produced bacterial biomass (supernatant) was mixed with silver nitrate to produce silver nanoparticles. Escherichia coli acting as reducing agents to produce nanoparticles. The colour changes from colourless to brown was observed to indicate the formation of silver nanoparticles. It was further reconfirmed using UV-Vis Spectroscopy, where the peak at 300 nm confirmed the formation of AgNPs. The antimicrobial and cytotoxicity activity of synthesized nanoparticles was tested. At 1 mg/ml concentration, the nanoparticles were effective against all the micro-organisms tested, Bacillus subtilis (12.7±2.5 mm) Staphylococcus aureus (13.7±2.3 mm), Pseudomonas aeruginosa (14.3±2.3 mm) and Aspergillus niger (12.7±2.1 mm). With decreasing concentration, the antimicrobial activity also decreased. Similar results were obtained when the nanoparticles were tested for cytotoxicity ability on HeLa cells. With increasing concentration, more of the tumor cells were inhibited. Based on the result obtained, it can be concluded that Escherichia coli can be used in the production of silver nanoparticles. It was found that synthesized nanoparticles possess effective antimicrobial and cytotoxicity activities. Thus, these properties could make them an advancing field in the medical world.