Bandgap-level engineered photodynamic antibacterial film with boosting ROS production for long-term fruit preservation

The growing demands for fruit preservation have inspired researchers to concentrate on developing advanced food packaging films with sustained and efficient antimicrobial properties. Herein, a visible light-powered photodynamic antimicrobial packaging system with enhanced reactive oxygen species (ROS) production capability (Bi/BiOI 1-x -CS) was developed by demand-driven engineering of the bandgap structure of the photo-responsive filler (Bi/BiOI 1-x ) and the ingenious selection of chitosan matrix (CS) with bacteria capture and killing capabilities. This film displayed excellent photocatalytic killing performance against Staphylococcus aureus ( S. aureus ) and Escherichia coli ( E. coli ) under the visible light, with the bactericidal efficiency up to 99.36 % and 99.54 %, respectively. The enhancement stemmed from the reasonable optimization of the following two aspects: (i) The iodine defects and lateral modification of pure bismuth jointly optimized the electronic band structure of BiOI and significantly boosted the ROS production level, and (ii) The capturing characteristic of CS on bacteria might shorten the diffusion distance between ROS and bacteria, thus further amplifying the bactericidal effect of ROS. As a result, the as-prepared Bi/BiOI 0.20 1-x -CS film (0.20 shows the Bi/BiOI 1-x amount in film solution) exhibited enhanced preservation ability, significantly extending the shelf life of kumquats from 18 to 27 days. Meanwhile, the introduction of Bi/BiOI 1-x successfully promoted the mechanical properties, ultraviolet-barrier performance, and hydrophobicity of CS film. The enhancement of comprehensive performance underscores the potential application of Bi/BiOI 1-x -CS film in the field of fruit preservation.