Dual-crosslinked injectable polysaccharide-based hydrogel with synergistic photothermal-controlled release of black phosphorus-baicalein for accelerating wound healing

A key challenge in multifunctional injectable wound dressings is the lack of integration between the appropriate mechanical strength, the effects of antibacterial, antioxidant and pro-healing properties. In this study, a pioneering research has been designed with the polymerization between oxidized dextran (ODex) and carboxymethyl chitosan (CMCS) to develop a double cross-linked injectable hydrogel (OD/CM/BP@Bai). This hierarchical structure combines a physically entangled network (providing immediate mechanical integrity) and a dynamic covalent network (enabling self-healing and injectability), resulting in a composite hydrogel with a storage modulus (G') approximately twenty times higher than that of single-network ODex pre-gel. Innovatively, black phosphorus nanosheets (BPNS) were incorporated as dual-functional elements, acting concurrently as photothermal conversion agents and nanoscale drug reservoirs. Through π–π stacking interactions, a high drug loading rate of 5.6 % was achieved for the hydrophobic drug baicalein (Bai). Incorporation of the nanoparticles further enhanced the overall mechanical properties of the hydrogel. Under near-infrared (NIR) irradiation, the hydrogel enabled synergistic and on-demand therapy. The photothermal effect not only directly eradicated bacteria but also triggered rapid Bai release. Through the synergistic interaction of functional components (CMCS/Bai/BPNS), a responsive hydrogel integrating antibacterial, anti-inflammatory, and pro-regenerative performances was constructed, which provides an innovative solution for wound treatment.