An Engineered Nanocomposite Copper Coating with Enhanced Antibacterial Efficacy

Abstract

Contaminated surfaces are a major source of nosocomial infection. To reduce microbial bioburden and surface-based transmission of infectious disease, the use of antibacterial and self-sanitizing surfaces, such as copper (Cu), is being explored in clinical settings. Cu has long been known to have antimicrobial activity. However, Gram-positive microorganisms, a class that includes pathogens commonly responsible for hospital-acquired infection such as Staphylococcus aureus and Clostridioides difficile, are more resilient to its biocidal effect. Inspired by inherently bactericidal nanostructured surfaces found in nature, we have developed an improved Cu coating, engineered to contain nanoscale surface features and thus increase its antibacterial activity against a broader range of organisms. In addition, we have established a new method for facilitating the rapid and continuous release of biocidal metal ions from the coating, through incorporation of an antibacterial metal salt (ZnCl2) with a lower reduction potential than Cu. Electrophoretic deposition (EPD) was used to fabricate our coatings, which serves as a low-cost and scalable route for modifying existing conductive surfaces with complex shape. By tuning both the surface morphology and chemistry, we were able to create a nanocomposite Cu coating that decreased the microbial bioburden of Gram-positive S.aureus by 94% compared to unmodified Cu.

Corrosion behavior of Cu in accelerated hydrogen peroxide-based disinfectants

“…The surface morphology and chemistry of the Cu coupons after 7 days of immersion were analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Details of the XPS analysis are described elsewhere [27]. Before and after the immersion tests the pH of the solutions was measured using an Oakton Instruments pH 110 Meter.…”