A thermosensitive chitin hydrogel with mild photothermal-chemotherapy for facilitating multidrug-resistant bacteria infected wound healing

Bacterial infection of skin wounds leads to serious health problems, including skin defects, inflammatory pain, and even death. To meet the requirements for successful treatment of complicated wounds, a multifunctional dressing is thus highly desirable. In this work, a thermosensitive hydrogel dressing (HBCA) exhibiting injectability, adaptiveness and mild photothermal antibacterial activity was developed for effective infected wound treatment. The HBCA hydrogel was constructed by integrating Ag NPs-incorporated quaternized chitin (DQCA) into the matrix of hydroxybutyl chitin. Laser irradiation could activate the photothermal DQCA to generate heat and rapidly induce the destruction of the bacterial integrity. Meanwhile, the release of DQCA can be accelerated by laser-mediated heating in a controllable manner, quickly reaching the effective concentration and leading to bacterial inactivation in a combined way. The HBCA hydrogel possessed broad-spectrum antibacterial and antibiofilm effect under mild temperature (similar to 48 degrees C), through combining photothermal therapy (PTT) with chemotherapeutic DQCA. Furthermore, the mouse full-thickness MRSA-infected wound healing test demonstrated that the HBCA hydrogel could accelerate wound regeneration by reducing the inflammatory response, promoting re-epithelialization as well as collagen maturation. This work presents an efficacious and straightforward antibacterial hydrogel dressing that incorporates mild-temperature PTT, particularly in the realm of multidrug-resistant bacterial infection therapies.