Anodized Aluminum with Nanoholes Impregnated with Quaternary Ammonium Compounds Can Kill Pathogenic Bacteria within Seconds of Contact

Bacterial contamination of surfaces results in the spread of pathogens in public spaces such as hospitals and public transport. The development of antibacterial surfaces that rapidly kill bacteria is therefore highly desirable. Here, we investigate the antibacterial efficacy of a novel anodized aluminum surface featuring nanoholes impregnated with quaternary ammonium compounds, referred to as A3S. The antimicrobial activity of A3S was assessed using both Gram-positive and Gram-negative bacteria in a novel assay which simulates pathogen transfer from a contaminated finger to a clean finger in a real-world scenario. Enumeration of colony-forming units shows that the number of viable bacteria on the second finger contacting A3S is significantly reduced compared to a control surface. Furthermore, bacterial contact with the A3S material results in compromised cell membranes in less than 1 min, and a kill zone assay shows that an exposure time as short as 5 s is sufficient to kill pathogenic bacteria. The rapid antimicrobial action of A3S was particularly evident against Gram-positive bacteria, that account for more than 70% of nosocomial infections. Taken together, these findings demonstrate that A3S is a promising candidate for the fabrication of antibacterial surfaces that can be used in a wide range of clinical and commercial applications to stop the spread of harmful bacteria.