Evaluations of Antibacterial Activity and Cytotoxicity on Ag Nanoparticles

E. coli and S. aureus were used as model for testing antimicrobial activity, and L-929 cell line was selected for toxicity evaluation by cellular mitochondrial function (MTT assay). The results show that silver nanoparticles (Ag NPs) can significantly increase antibacterial activity with the increasing of concentration of the silver nanoparticles. The lowest effective concentration of silver nanoparticles (30×10−6) which leads to more than 50% of inhibition in liquid medium and agar plate on bacterias is still satisfactory but will produce potential cytotoxicity. Even at 3×10−6 concentration of silver nanoparticles the cytotoxicity still exists with 2 grade which represents 26%-50% of cell growth inhibited, and 30×10−6 displays similar impact.