Design of an anti-scald photothermal hydrogel for rapid bacteria removal and hemostasis

Applying hydrogels as medical dressing in treating wounds has become a research hotspot in recent years. Photothermal hydrogels with antibacterial properties and favorable biocompatibility offer great potential for treating infected wounds. However, the risks associated with photosensitizer leakage and excessive heat cause edema and vascular damage, cutting off the nutrients and oxygen supply and slowing the wound healing rate. Herein, a bilayer hydrogel (AuDG2) containing the photothermal and heat-absorbing hydrogel layers is developed to generate adequate heat for quick bacteria removal and tissue protection. In this system, Au nanoparticles are firmly fixed to the nano-hydroxyapatite and coated in the photothermal hydrogel layer, effectively avoiding the leakage of the photosensitizer. Near-infrared imaging shows AuDG2 hydrogel maintains 48–50 °C at the wound by heat exchange between the two layers of it. This property enables AuDG2 to have an 89.68 % clearance rate against Staphylococcus aureus (S. aureus) and a 73.03 % removal efficiency of Escherichia coli (E. coli) within 5 min, increasing the healing area of infected wounds by 26.45 % compared to the normal saline treatment group, without adverse effects from burns, and evaporate water from the blood to stop blooding in a very short time. This anti-scald photothermal hydrogel structure is simple in preparation, offering the possibility to mitigate the side effects of photothermal therapy.