Construction of Vine-Inspired Antimicrobial Filter with Multiscale 3D Nanonetwork for High-Efficiency Air Filtration

Enhancing the antimicrobial activity of high-efficiency particulate air (HEPA) filters while maintaining filtration efficiency and pressure drop is currently an urgent issue for preventing the spread of pathogenic microorganisms. Herein, inspired by vines which can enwind fences to fix as well as decorate them, a flexible antimicrobial chitin nanofiber (ChNF@CuO_x) was fabricated and loaded onto the rigid glass fiber (GF) skeleton of a HEPA filter. Through the physical interaction, ChNF@CuO_x was spontaneously enwound on GF, and ChNF@CuO_x itself interweaved to form a new nanonetwork between the GF skeleton. The obtained antimicrobial air filter (ChNF@CuO_x/GF) with a unique nanonetwork increased the filtration efficiency of the HEPA filter. Meanwhile, it possessed excellent inactivation ability against Staphylococcus aureus, Escherichia coli, and Candida albicans due to the urchin-like in situ grown CuO_x on the ChNF. In particular, the oxygen vacancies generated unexpectedly in CuO_x enabled it to produce reactive oxygen species. After eight cycles of antimicrobial assays, the antimicrobial rates of bacteria were higher than 99.5%, and those of fungi were greater than 98.3%. The successful synthesis of antimicrobial fibers and the construction of multidimensional nanoscale structures through a simple postprocessing method provide a new design mentality for antimicrobial functionalization for HEPA filters.