Copper-nanoparticle-coated fabrics for rapid and sustained antibacterial activity applications

The scientific community has recognized that copper can kill bacteria; however, the effect of the particle size, concentration, and oxidation state on antibacterial activity remains unclear for copper and its nanoparticles (NPs), in particular. In this study, copper NP coatings with extremely fast and sustained antibacterial activity are reported. It is found that coating with cuprous oxide (Cu2O) NPs (∼150 nm) and coating with metallic copper NPs (∼50 nm) on commonly used fabrics for cleaning and masks can kill bacteria within 45 s. Our bacterial study was conducted using Staphylococcus aureus as a Gram-positive bacterium and Klebsiella pneumoniae and Pseudomonas aeruginosa as Gram-negative bacteria. Scanning electron micrographs suggest bacterial damage, and bacterial DNA harvested after interaction with copper-coated fabrics indicates DNA fragmentation. On top of this, significantly higher levels of 8-hydroxy-2′-deoxyguanosine are also detected in DNA after interaction with coated fabrics, signifying that both copper and Cu2O NPs rapidly induce oxidative stress. Furthermore, cumulative inoculations with K. pneumoniae for 144 h show excellent sustained bacterial killing in the presence of Cu2O NPs. Using a combination of detailed physical and chemical analysis of the NPs and a study of how bacteria interact with the coated substrate, it is possible to establish the parameters that resulted in speedy and robust antibacterial properties in Cu2O-coated fabrics. This study offers a rational strategy on how to slow down or even halt the transmission of infectious pathogens. Ministry of Education (MOE) This research was supported by the Ministry of Education, Singapore, under its Academic Research Fund Tier 1 (Project RG98/19). Y.-H.G. acknowledges financial support given by Kuprion, Inc. (USA), for this work.