Dual-Responsive Nanocomposites for Synergistic Antibacterial Therapies Facilitating Bacteria-Infected Wound Healing

The rising dangers of bacterial infections have created an urgent need for the development of a new generation of antibacterial technologies and therapeutics. Antibacterial photodynamic therapy (PDT), considered as a noninvasive treatment with no drug resistance, has become a new promising photochemistry-involved treatment strategy. Titanium oxide (TiO₂ ) is proved to be a very efficient PDT agent among the photosensitive materials, while the property of a large bandgap of TiO₂ makes it only be excited by ultraviolet light, which is harmful to organisms. In this work, a novel ligand-to-metal charge transfer (LMCT) mediated TiO₂ PDT strategy is proposed via the harmless near-infrared light irradiation. By choosing a mussel-inspired material, polydopamine (PDA) is involved in forming mesoporous TiO₂ @PDA nanoparticles (mTiO₂ @PDA NPs). The catechol groups of PDA can attach the TiO₂ tightly even in colloidal environments, and can also form the LMCT bridge, exciting TiO₂ to exert PDT function via 808 nm irradiation. Combining the sonodynamic therapy (SDT) of TiO₂ and the photothermal therapy properties of PDA, this simple structure mTiO₂ @PDA enables synergistic antibacterial applications with multiple functions under the dual excitation of NIR and ultrasound. This reliable all-in-one NPs can achieve great antibacterial effect and a rapid repair of infected wounds.