Electroactive nanostructured antibacterial materials

Abstract

Thin nanostructured metal (Au, Ag) films, magnetron-sputtered on semiconductor (n-type Si) substrate under 6 V voltage exposure for 15 min, exhibit high antibacterial effect against the food pathogens S. aureus and P. aeruginosa. Nanostructures were formed by femtosecond laser ablation, resulting in an array of microspots. The observed effect is caused by the emergence of submicron, laterally periodical static electric and magnetic fields, adjacent to the metal film, causing the abrupt voltage drops, which induce the hyperpolarization of the cell membrane and increase its permeability, resulting in the formation of pores (electroporation) in the membrane and the subsequent apoptosis of the bacterial cell. Additional factors, which enhance the antibacterial effect of the studied materials, are the volume convection in the liquid drop with bacterial culture, caused by the moderate heating of the substrate to 45 °C–50 °C during the electric current flow and electro-taxis of bacteria to the charged nanostructured metal film.