Antimicrobial efficacy of solar disinfection in cellulose fiber supported photoactive materials

According to the World Health Organization, antimicrobial resistance is one of the emerging threats to global health. Therefore, the development of new strategies to mitigate resistant bacterial strains is highly desirable. Photodynamic inactivation is a promising approach owing to its effectiveness against a broad range of microorganisms irrespective of their antibiotic resistance profile and its multitarget mechanism that hamper the appearance of acquired resistance. In this work, a self-sterilizing and potentially biodegradable material is developed, providing a green alternative for single-use packaging in the medical, food, and cosmetic industry. We demonstrate two synthetic approaches based on covalent linkage of toluidine blue to tempo-oxidized carbon nanofibers, as well as the supramolecular immobilization based on electrostatic self-assembly. The former shows high activity, reaching inactivation rates of 8 Log₁₀ CFU for S. aureus and E. coli after 15 min under 250 W·m⁻² artificial sun irradiation. This simple and facile approach will enable the preparation of composite photoantimicrobial films that are light activated, providing clean and microbiologically safe surfaces, even in challenging situations, such as natural disasters or conflicts, or remote locations with of none or limited access to other forms of energy supply.