Composite multilayer nanomaterials for photothermal sterilization of pathogenic bacteria in milk and water

Sterilization technologies for microorganisms in food are limited by safety and antibiotic residue concerns and resistance, creating an urgent need for novel sterilization methods. Photothermal conversion nanomaterials can rapidly convert near-infrared light into thermal energy, offering fast, efficient, and environmentally friendly sterilization, leading to their increasing application. Herein, we designed and prepared a composite multilayer photothermal nanomaterial (MCOF@Au@PEI NPs), integrating “capture-photothermal sterilization-separation and recycling” functions and achieving rapid and efficient sterilization. The material maintains high photothermal conversion efficiency even after multiple cycles and exhibits excellent biocompatibility. Using Escherichia coli and Staphylococcus aureus as model bacteria in milk and drinking water, the material achieves a 100% bacterial sterilization rate within 435 seconds under irradiation, equivalent to pasteurization. Moreover, the material exhibits potent destructive effects on bacterial biofilms, showing broad application prospects in developing novel nano-photothermal sterilization methods and antibiotic alternative therapies.