A panther chameleon-inspired Vis-NIR light modulation hydrogel with enhanced photothermal effects and pH/temperature monitoring for bacterial infection theranostics

Bacterial infection theranostics combining antibacterial therapy and real-time diagnosis can effectively advance the healing process. Near-infrared (NIR) light has been widely utilized for antibacterial photothermal therapy (PTT) and visible light can provide visual cues for the status of treatment, whereas the lack of modulating light propagation hinders the development of high-performance light-based infection theranostics. Here, inspired by the hierarchical micro/nano-structures of panther chameleon skin composed of deep- and superficial-iridophores responsible for regulating NIR and visible light propagation, respectively, a photonic crystal hydrogel is developed for enhanced antibacterial PTT and colorimetric monitoring of pH and treatment temperature. The deep layer composed of large-sized particles in the hyaluronic acid methacryloyl-polyacrylamide hydrogel matrix exhibits a photonic bandgap overlapping NIR light, acting as a universal platform for boosting the photothermal conversion efficiency (PCE) of embedded photothermal agents. As typical examples, 1.75-, 1.80-, and 1.94-fold increases in PCEs are achieved for embedded carbon black, carbon nanotubes, and MXenes, respectively. The superficial layer consisting of small-sized particles and a poly(2-(dimethylamino)ethyl methacrylate) hydrogel matrix is responsible for visible light modulation, exhibiting rapid, high-sensitivity, and broad-range color variations at different pH/temperatures. Benefiting from these light modulation capabilities, high-efficacy and multifunctional bacterial infection theranostics are realized, synergistically facilitating the healing of infected wounds.