Engineering wettability-controlled copper surfaces to mitigate airborne bacterial contamination in hospitals

Abstract

Hospital-acquired infections remain a critical challenge in healthcare, with pathogens often proliferating via contaminated surfaces and aerosol transmission through ventilation systems. While copper-based materials are recognized for their intrinsic antimicrobial properties, their real-world efficacy in clinical settings – where factors like surface contamination, exploitation wear, and sanitization protocols interact dynamically – remains underexplored. This study investigates the long-term antimicrobial performance of copper-coated ventilation grates with engineered wettability (ranging from superhydrophilic to superhydrophobic) in the intensive care unit over 325 days. By comparing these surfaces to steel counterparts, we evaluated microbial colonization dynamics under operational conditions, including aerosol-deposited contaminants and routine swab sampling. The analysis of surface wettability and roughness to assess the degradation of deposited coatings and its impact on antibacterial activity showed that for all grates significant alterations in the contact angles from these for the freshly fabricated grates were observed. For the initially superhydrophilic substrate, the contact angle approached 90°, while for the superhydrophobic coating, it deteriorated from 162° to 150°. Results revealed that with respect to various bacterial strains, superhydrophilic and superhydrophobic copper surfaces outperformed both the smoother sputtered copper and the steel, highlighting the efficiency of the extreme wettability surfaces in reducing microbial contamination in clinical settings. After 325 days of clinical exposure, the cumulative number of swabs contaminated with microorganisms from the steel grate was found to be 2.7, 2.3, and 1.4 times higher than the corresponding values for the superhydrophobic, superhydrophilic, and smooth copper grates, respectively. This work bridges the gap between laboratory studies and real-world application and offers a strategy to curb nosocomial infections without disrupting clinical workflows.