On-demand release of CO2 from photothermal hydrogels for accelerating skin wound healing

[Display omitted] •Carbon nanoparticles (CNPs) obtained from chitosan for the loading of bicarbonate.•Immobilization of CNPs within thermosensitive hydrogels.•On-demand delivery of CO2 triggered by light for enhanced wound healing efficiency.•Composite hydrogels showing good biocompatibility and antibacterial capability. Acceleration of skin wound healing is an important aspect of wound treatment. The use of carbon dioxide (CO2) has been recognized as one of the most effective ways to improve microcirculation and to benefit wound healing, while the need of the specialized equipment and the uncontrollable delivery of gas CO2 might restrict such strategy in wide applications. Herein, we develop a photothermal hydrogel for the on-demand and localized delivery of CO2 to accelerate skin wound healing by combining thermoresponsive block copolymer (BCP) of Pluronic F127 and carbon nanoparticles (CNPs) with amino groups, which can be used for loading CO2 precursor of bicarbonate for controlled release. We show that by rationally optimizing the content of the thermoresponsive BCP in the photothermal hydrogel, a liquid-to-solid transition triggered by the body temperature can be achieved. Under light irradiation, the CNPs can convert light into heat, triggering the decomposition of the bicarbonate, and the photothermal hydrogel can thus locally release CO2 in the wound site. Wound healing can be accelerated by improving local microcirculation disturbance and increasing tissue oxygen concentration. This study provides a new opportunity for local CO2 supplement for accelerating wound healing.