Fabrication of antibacterial nanopillar surface on AISI 316 stainless steel through argon plasma etching with direct current discharge

Abstract

The present study demonstrated that argon (Ar) plasma etching with direct current (DC) discharge leads to the formation of antibacterial nanopillars on AISI 316 stainless steel with a comparatively short processing duration. Small protrusions appeared initially, and then transformed into nanopillars of hundreds of nanometers in size with prolonged plasma etching durations up to 60 min. The dimensions of the nanopillars could be controlled by adjusting the applied current to generate the plasma. The height and the base and cap diameters of the nanopillars increased with increasing applied current, whereas an excessively high current reduced the density of the nanopillars. The fabricated nanopillars functioned as an antibacterial surface, which reduced the survival rates of bacterial strains; however, the reduction in the survival rate of gram-positive Staphylococcus epidermidis was mitigated compared to that of gram-negative Escherichia coli. Moreover, the degree of antibacterial activity varied depending on the dimensions of the nanopillars. In conclusion, Ar plasma etching with DC discharge is an effective method for the rapid fabrication of antibacterial nanopillars with optimal dimensions on AISI 316 stainless steel surfaces.