Nanofibrillated collagen fiber networks for enhanced air purification.

Air filtration is essential for protecting human health, but commercial synthetic microfiber filters face challenges like complex manufacturing, poor biodegradability, limited biocidal properties, and reduced efficacy against volatile organic compounds and nanoscale particulates. Collagen fiber networks derived from animal hides offer a sustainable alternative due to their hierarchical structure and diverse surface functionalities. However, their thick fiber bundles (>5 μm) hinder filtration performance. Here we introduce a facile strategy combining physical processing and zwitterionic copolymer functionalization to disperse fibrils, followed by zirconium treatment for stabilization. The resulting filters, with finely dispersed nanofibrils (~120 nm) and increased exposure of functional groups, significantly enhance air purification, achieving 97% PM0.3 removal and nearly doubling formaldehyde elimination. These filters also exhibit robust antimicrobial properties, capturing and inactivating over 99% of bacterial aerosols. Life-cycle assessments demonstrate their biodegradability and cost-effectiveness, showcasing strong potential for large-scale production. This approach not only advances the use of nature-derived collagen fibers for air purification but also opens possibilities for broader applications, including nanomaterial separation and water purification.