Antibacterial activities of polyethylene glycol, tween 80 and sodium dodecyl sulphate coated silver nanoparticles in normal and multi-drug resistant bacteria.

Antibacterial activity of silver nanoparticles coated with different functionalizing agents i.e., polyethylene glycol, tween 80 and sodium dodecyl sulphate were evaluated on both normal and multi-drug resistant strains of bacteria. Under the same reaction conditions, these functionalizing agents were added separately to coat silver nanoparticles. Among these, polyethylene glycol coated nanoparticles were most effective in killing all the bacterial strains which includes Escherichia coli DH5a, Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus and multi-drug resistant clinical isolates of Shigella spp. (flexneri, boydii, sohnea) and Vibrio cholerae. The minimum inhibitory concentration of polyethylene glycol coated silver nanoparticles was also less compared to the other two sets of nanoparticles. Consistence with that polyethylene glycol coated nanoparticles produced more intracellular reactive oxygen species in bacteria. Moreover, when human cell lines MCF7 and Chang Liver were incubated in presence of these nanoparticles for 18 h with same concentrations as used for bacteria, no toxicity was observed. But significant increase in cell killing was observed with longer incubation time. Thus our present investigation implicates the potential therapeutic use of silver nanoparticles as antibacterial agent particularly the polyethylene glycol coated one.