Biogenic synthesis of antimicrobial silver nanoparticles capped with l-cysteine

Abstract

The number of medical applications of silver nanoparticles is constantly expanding due to their high bactericidal properties coupled with low toxicity towards mammalian cells. Because of this expanding use of silver nanoparticles, novel methods of synthesis have been developed in order to achieve nanoparticles preparation through inexpensive and environmentally friendly processes; biogenic synthesis of silver nanoparticles is an approach that meets those requirements.In this work, Escherichia coli cultures centrigugates were used to synthesis l-cysteine capped silver nanoparticles. The ratio between AgNO3 and l-cysteine has been proven to affect the size of the nanoparticles: higher amount of l-cysteine returns smaller nanoparticles, but does not affect the percentage of organic matter in the nanoparticles as determined through TGA.The silver nanoparticles prepared had antimicrobial activity against E. coli and Staphylococcus aureus with Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) independent of the nanoparticles size; for both bacterial species the values of MIC and MBC were the same, 0.0432mg/ml for E. coli and 0.0216mg/ml for S. aureus.