# Injectable carbon dioxide controlled releasing and photothermal carboxymethyl chitosan-alginate-black tea carbon hydrogel dressing for diabetic wound healing

## TL;DR

A new injectable hydrogel dressing uses CO2 release and photothermal effects to improve diabetic wound healing and reduce infection risks.

## Contribution

A novel injectable hydrogel that combines CO2 release via the Bohr effect, photothermal conversion, and antimicrobial properties for diabetic wound healing.

## Key findings

- The hydrogel released CO2 under near-infrared light, enhancing oxygen availability in wounds.
- The dressing showed antimicrobial activity and promoted cell migration and collagen deposition in diabetic mice.
- In vivo experiments confirmed accelerated wound recovery and angiogenesis in diabetic models.

## Abstract

The microenvironment of diabetic wounds is at risk of slow recovery, scarring and infection in medical treatment. Although many hydrogel dressings combine photothermal and gas therapies, few use CO2’s Bohr effect to enhance oxygen release while offering precise, in situ control over gas and drug release. To address this, we designed an injectable multifunctional hydrogel dressing with photothermal, antibacterial, and near-infrared (NIR) - induced CO2 properties. In this work, we developed carboxymethyl chitosan-alginate-black tea carbon conjugated with CO2-precursors (CMCS/Alginate/BTC-CO2) dressing. The black tea hydrothermal carbon nanoparticles attached CO2 precursors on the surface, thermally decomposed under near-infrared irradiation to release CO2 gas. Meanwhile, the excellent photothermal conversion efficiency enabled the hydrogel complex to demonstrate antimicrobial function. The high absorption in the UV range prevents the deposition of melanin. The CMCS/Alginate/BTC-CO2 hydrogels exhibited good cytocompatibility and synergistically promoted NIH/3T3 cell migration. In vivo experiments in diabetic model mice verified that treatment of NIR-conjugated CMCS/Alginate/BTC-CO2 hydrogels accelerated wound recovery, angiogenesis, and collagen deposition. Overall, we designed and verified the combination of stimuli-responsive photothermal CO2 release from NIR, antimicrobial, and injectable multifunctional hydrogels, providing an effective solution for promoting diabetic wound healing both in vivo and in vitro. Such multifunctional dressing is expected to accelerate the process of wound treatment and alleviate the adverse reactions after recovery.