Light-Driven Antimicrobial Cotton Fabric: Multilayer Dye-Finishing Design and Hospital Environment Validation

A sequential ionic multilayer finishing strategy enabled the stable co-immobilization of two photosensitizing dyes-cationic methylene blue (MB) and anionic Rose Bengal (RB)-onto cotton fabrics, overcoming cellulose-dye incompatibility through chitosan interlayers and cyanoguanidine fixation. The resulting multifunctional fabric (MF) preserved fiber integrity, while the dual-dye assembly broadened visible-light absorption and maintained the independent photosensitizing activity of each dye, enabling rapid and broadband antimicrobial action under white light. The material achieved complete inactivation of E. coli and E. faecalis within 60 and 20 min, respectively, ∼6-log suppression of C. albicans after 3 h, and ∼6-log inactivation of rAd5 within 60 min. Antimicrobial performance remained durable after repeated washing, consistently exceeding standard antimicrobial benchmarks. A pilot hospital validation further confirmed its translational potential, showing a 75% reduction in microbial load under ambient lighting, particularly against Gram-positive species (77.5%), and outperforming dark controls. Taken together, this architecture provides durable, resistance-free, self-disinfecting performance compatible with clinical workflows, offering a promising strategy to reduce microbial persistence in healthcare environments.