Keywords: Antimicrobial copper; copper coating; electrodeposition; nanostructured coating

Abstract

Antimicrobial copper is beneficial in reducing hospital-acquired infections. Alteration of stainless steel by coating with copper makes the top surface antimicrobially active. In this study, nanostructured copper-coated stainless steel (Cu/SS) with excellent physicochemical properties and outstanding antibacterial activity was successfully prepared by electrodeposition technique. The physicochemical properties of the copper coating such as ultrafine nanostructured particles with grain diameter of 25 nm to 42 nm, rough surface with 24.23 nm, and low water contact angle (82o) would contribute in enhancing the antibacterial activity of the coating. Adhesion strength between the coating and stainless steel substrate is very good, as indicated by 100% of retainment of copper on the stainless steel surface tested using Scotch® tape. The antibacterial activity showed no significant difference between nanostructured copper-coated stainless steel and C11000 copper in terms of reduction of Staphylococcus aureus (S. aureus). However, only 5 minutes was required to completely kill Escherichia coli (E. coli) using nanostructured Cu/, while longer time (i.e., 10 minutes) using solid copper. The dissolution rate of nanostructured Cu/SS in simulated hand sweat solution was 0.08048 mm/year. The nanostructured copper coating also has high surface roughness and low surface wettability (i.e., high hydrophobicity). These findings indicate that the modification of stainless steel with copper nanostructures can improve the antibacterial activity of stainless steel. The Cu/SS coating can be an ideal material to be used as touch surface in combating bacterial infection, especially in hospitals and public areas.