Enhancing the contact-killing effect of copper by surface laser texturing

Abstract

Copper is a metal well known for its antimicrobial properties. However, copper-made structures such as pipes and clinical supplies are prone to be colonized by copper-tolerant bacteria. Recent works have shown that modifications of the topography and surface chemistry of metals using direct laser interference patterning (DLIP) affect bacterial settlement. In this work, DLIP was used to texture copper surfaces with parallel line patterns on the size scale of a bacterium. The effects of texturing on the copper surface were characterized by scanning electron microscopy, atomic force microscopy, contact angle and corrosion analyses, and X-ray photoelectron spectroscopy. The antimicrobial properties were assessed by using the live/dead test. Experiments were performed on both the copper-tolerant bacterium Variovorax sp. and the noncopper-resistant bacterium Escherichia coli. Our results indicate that although the increase in Cu(OH)2 might influence the toxicity of the surface, the controlling factor of the antimicrobial activity of laser-textured copper surfaces is the contact area per bacterium. This work highlights the application of laser texturing technologies to enhance the antimicrobial behavior of metals.