Dopamine-polyphenol self-assembled nanoparticle functionalized soy protein isolate films

To overcome the instability and rapid release of natural antimicrobial agents, a photothermal-responsive soy protein isolate (SPI) film was developed by incorporating polydopamine–tea polyphenol nanoparticles (PDA@TP NPs). PDA@TP NPs were synthesized via dopamine self-polymerization and Michael addition, achieving 86.82 % tea polyphenol (TP) encapsulation. Under 808 nm near-infrared (NIR) irradiation, the film rapidly reached 61 °C, enhancing antibacterial activity (99.2 % and 95.3 % inhibition against S. aureus and E. coli ) and enabling controlled TP release. Compared to direct TP addition, PDA@TP NPs improved thermal stability and sustained-release efficiency. The nanocomposite film exhibited enhanced tensile strength (13.5 % increase), reduced water vapor permeability (10.33 × 10 −10  g·m·m −2 ·Pa −1 ·s −1 ), and UV-blocking properties. In strawberry preservation trials, the film extended shelf life from 4 to 8 days under ambient conditions while maintaining fruit quality. This work provides a biodegradable, multifunctional packaging solution integrating photothermal antibacterial action and on-demand release for sustainable food preservation.