A Photothermal-Responsive, Self-Contractile, and Highly Adhesive Double-Network Hydrogel

Existing dressings primarily rely on biochemical mechanisms, such as protective functions and drug loading, to promote healing; however, they are often suboptimal in chronic wound repair. PNIPAm-based hydrogels, with their thermo-responsive self-contraction properties, offer a non-pharmaceutical, mechanically regulated repair solution. However, their contraction behavior is highly dependent on body temperature conduction, which can be intermittent, making it difficult to meet the repair needs of complex wounds. To address this issue, in this study, a photothermal dual-responsive PNIPAm-CMCS@TA-Mg²⁺ (PCTM) dual-network hydrogel was developed. The TA-Mg²⁺ complex network provides precise temperature control through photothermal conversion and enhances adhesion and structural stability in collaboration with CMCS. The PNIPAm network achieves photothermal self-contraction and volume regulation through thermally sensitive phase transitions. Through the synergistic effect of photothermal regulation and thermally sensitive phase transitions, the hydrogel achieved a volume contraction of 54.8% and its swelling ratio decreased by 32.41% at 37°C, with an adhesion strength of up to 42.8 kPa. After 10 min of near-infrared (808 nm) light irradiation, the volume contraction rate increased to 65.78%. This study provides an intelligent material solution for complex wound repair through a photothermal-thermally sensitive synergistic mechanism, significantly enhancing the precision and adaptability of mechanically regulated repair.