A Versatile and Bioinspired Hierarchical Nanoflower Coating for Enhanced Photodriven Antimicrobial Efficacy against Foodborne Pathogens

Contamination by pathogenic microbes frequently occurs on the surfaces of solid materials, posing serious threats to food safety and human health. To mitigate the spread of pathogens and reduce the risk of antimicrobial resistance, there is an urgent need for nanostructured surface modification materials that offer high bactericidal efficiency without relying on conventional antimicrobial agents or antibiotics. In this study, we report a green and facile approach for fabricating antimicrobial nanoflower (PDA-Cu NFs) coatings on solid substrates, including polystyrene, glass, and stainless steel via one-step biomimetic mineralization. The resulting coatings exhibited uniform nanoflower morphology, strong substrate adhesion, and superhydrophilicity (contact angle = 0°). Under ultraviolet A (UV-A) irradiation, the PDA-Cu NFs coatings demonstrated excellent bactericidal efficacy against <i>Listeria innocua</i> and <i>Escherichia coli</i>, achieving more than 4 log CFU/cm² of reduction within 1 h of treatment. This enhanced antimicrobial performance is attributed to a triple-mode synergistic combination of photothermal effects, photoinduced reactive oxygen species generation, and the hierarchical nanoflower structure, which increases bacterial contact with copper ions and induces physical membrane disruption. Durability testing revealed that the coatings maintained their hydrophilic properties even after five cycles of mechanical abrasion with only partial structural damage observed. These findings present a robust and substrate-independent strategy for developing durable, superhydrophilic, and UV-activated antimicrobial coatings, offering significant potential for applications in healthcare, food processing, and environmental sanitation.