Enhanced Photosensitizer Wettability via Anchoring Competition of Violet Phosphorus Quantum Dots for Breakthroughs in Photodynamic Film Sterilization

Wettability is important for photodynamic film sterilization since higher wettability enhances the capture of bacteria in contact with photosensitizers. Herein, a small number of violet phosphorus quantum dots (VPQDs) are anchored into hypericin bacterial cellulose films (VP/Hy-BC films) to improve wettability, reducing the water contact angle from 56.8° to 33.0°. This modification facilitated more effective interactions between the bacteria and photosensitizers, rapidly inactivating 7 log₁₀ CFU/mL of Staphylococcus aureus within 60 min. First-principles calculations and molecular dynamics simulations reveal that VPQDs, with their low spatial site resistance, reduced the intermolecular Hy self-aggregation force. This increased the solvent-accessible surface area of VP/Hy by ≈25.7%, thereby decreasing hydrophobic photosensitizer aggregation. Consequently, more active sites are exposed, remarkably improving the photoelectron transfer efficiency. VP/Hy-BC demonstrated exceptional efficacy in inhibiting bacterial proliferation; for instance, it extended beef shelf life by up to 10 days. The findings of this study will aid the development of health-conscious, eco-friendly, and efficient antimicrobial packaging films.