Tissue wounds afflict millions of individuals annually, giving rise to significant social and economic concerns. Previous investigations have demonstrated the remarkable potential of hydrogels in wound healing owing to their exceptional capabilities in absorbing wound exudate, moisturizing, facilitating oxygen permeation, and possessing a three-dimensional porous structure[1]. However, natural polymer-based hydrogel dressings for wounds often suffer from susceptibility to bacterial growth and subsequent infection, which represents a major obstacle impeding the wound healing process.
Photothermal therapy (PTT) is a strategy to achieve antibacterial effect through rapid hyperthermia produced by a photothermal agent under near-infrared (NIR) light radiation (700-1100 nm). Compared with conventional antibacterial methods, PTT offers distinct advantages including heightened sterilization potency, reduced treatment duration, and diminished risk of drug-resistant bacteria[2]. We previously synthesized stable tricomplex molecules (PA@Fe) assembled by protocatechualdehyde (PA) and ferric iron, which were subsequently embedded in a gelatin hydrogel (Gel-PA@Fe). The embedded PA@Fe served as a crosslinker to improve the mechanical and adhesive properties of hydrogels through coordination bonds and dynamic Schiff base bonds, meanwhile acting as a photothermal agent to convert NIR light into heart to kill bacteria effectively[3]. The hydrogel was endowed with exceptional hemostatic and antioxidant properties by grafting serotonin onto the gelatin molecular chain, resulting in the preparation of a composite hydrogel (GelS-PA@Fe). As a mediator of blood coagulation, serotonin can interact with catechol-containing PA and chemical hemostatic agents, thereby enhancing the adhesion of more blood cells to the hydrogel surface. The free radical scavenging rate of GelS-PA@Fe (80.49%) exhibited a 1.5-fold increase compared to that of the Gel-PA@Fe hydrogel, indicating enhanced efficacy in neutralizing free radicals. Importantly, the introduction of serotonin did not compromise the biocompatibility and photothermal antibacterial properties of the GelS-PA@Fe hydrogel. Our results indicated the great potential of GelS-PA@Fe hydrogel in promoting infected wound healing.