Performance and Mechanism of Self-Oxygenated Perfluorohexane Nanosystem for Combined Photothermal/Photodynamic Bacterial Inhibition

Biofilms are responsible for most bacterial infections and significantly threaten human health. Designing effective and less harmful materials to inhibit and remove biofilms remains a significant challenge. Complex biofilm structures make conventional antibiotic treatments ineffective, and in recent years, photothermal therapy (PTT) and photodynamic therapy (PDT) have attracted attention for their ability to treat drug-resistant bacterial infections effectively. Therefore, a synergistic nanoantimicrobial system (PFH/TCPP@SL@PDA) enhances the effect through PTT and PDT. It is synthesized by loading meso-tetra(4-carboxyphenyl) porphine (TCPP) on soybean lecithin (SL), further coating perfluorohexane (PFH) and finally coating polydopamine (PDA) on the outer layer. The designed nanoantimicrobial system alleviates the hypoxic properties of the biofilm microenvironment by loading oxygen and enhances the effect of PDT to generate more reactive oxygen species. It significantly enhanced biofilm permeability and improved antimicrobial properties, with over 95% inhibition of multidrug-resistant (MDR) Escherichia coli and MDR Staphylococcus aureus while inhibiting and removing over 90% of biofilms. PDA not only acts as a good nanoshell but also induces relatively mild PTT and can facilitate the reaction of PDT. PFH/TCPP@SL@PDA has good biocompatibility, and the hemolysis test showed less than 5% hemolysis of erythrocytes, effectively relieving inflammatory symptoms and accelerating wound healing in mice model. In conclusion, this study provides an efficient and safe combined therapeutic strategy for the bacterial inhibition, suppression, and removal of biofilms.