Photothermal MXene-embedded tannin–Eu³⁺ particles as in situ bacterial vaccines for accelerating healing of wounds infected by seawater immersion and providing persistent anti-infection effects

The low temperature, high salt content, and bacterial composition of a seawater environment can induce severe infections in open wounds, thus impending wound healing. To date, numerous wound dressings have been developed to injuries and various antibacterial functions. However, ordinary antibacterial strategies could not provide long-term resistance to infections and could not promote wound healing. Here, we proposed a strategy for enhancing resistance to seawater immersion wound infection by killing bacteria and delivering bacterial antigens in situ. Specifically, MXene-embedded tannin–Eu³⁺ (M@TA–Eu) particles were constructed to effectively alleviate injuries infected through seawater immersion and persistently fight infection by forming in situ bacterial vaccines and immune memory. In the particle, the platform composed of TA and Eu³⁺ exhibited provascularization and antigen presentation effects. MXenes with near-infrared photothermal effect were introduced to kill the bacteria, promote the recruitment of antigen presentation cells, and ultimately enhance vaccination efficacy. Experimental results showed that the particles not only effectively accelerated the healing of injuries by relieving wound inflammation and inhibiting bacteria but also produced a potent vaccination by forming in situ bacterial vaccines. Therefore, the M@TA–Eu particles are novel materials for high-grade anti-infection dressing.