Peelable gelatin-based silver nanoparticle-decorated antimicrobial coatings for post-contamination surface sterilization

Abstract Surface contamination by pathogenic microorganisms poses a persistent challenge in healthcare, food processing, and public environments, where contaminated fomites serve as infection reservoirs. While most antimicrobial coatings aim to prevent contamination, the ability to actively decontaminate already-contaminated surfaces remains largely unmet. Here, a novel peelable gelatin-based silver nanoparticle (Ag@Gelatin) coating designed for post-contamination sterilization is reported. Silver nanoparticles (AgNPs) were synthesized via a green method, yielding an average diameter of 55.3 ± 7.1 nm, and subsequently embedded within a gelatin matrix confirmed by morphological and chemical analyses. The coatings exhibited significant antimicrobial activity against Escherichia coli , Staphylococcus aureus , and Candida albicans . Colloidal nanoparticles showed low minimal inhibitory concentrations (7.8–31.25 μg/mL), while the films achieved > 7 log reductions for all tested microorganisms. Time-resolved assays demonstrated complete surface decontamination within 4 h, characterized by a biphasic inactivation profile: an initial rapid phase (> 99% inhibition within 30 min) followed by a slower decline until full elimination. The coatings effectively sterilized various materials, including plastic, stainless steel, glass, ceramic, copper, and paper, and retained high efficacy over ten reusability cycles with minimal decline. Overall, Ag@Gelatin films represent a versatile, peelable, and reusable antimicrobial coating offering rapid and complete microbial eradication from contaminated surfaces.