# NIR Light‐Driven Photocatalytic Antibacterial Hydrogels for Synergistic MRSA Biofilm Eradication and Wound Regeneration

## TL;DR

A new hydrogel uses light to kill drug-resistant bacteria and promote wound healing, offering a promising treatment for infected wounds.

## Contribution

The first synthesis of Fe-Bi2O2-S nanoflowers for NIR light-driven antibacterial and wound regeneration applications.

## Key findings

- Fe-BOS@C/H Gel eliminates 97% of MRSA biofilms under NIR light.
- The hydrogel promotes cell proliferation and wound healing without light.
- Transcriptomic analysis reveals multiple antibacterial mechanisms of the hydrogel.

## Abstract

The treatment of drug‐resistant bacterial biofilm infections remains a significant challenge in clinical practice. To address this challenge, 3D oxygen vacancy (OV)‐rich iron‐doped Bi2O2S (Fe‐Bi2O2‐XS, Fe‐BOS) nanoflowers (NFs) are synthesized for the first time via an ion‐exchange method. The resulting material exhibits a small band gap, abundant OVs, and favorable charge‐transfer properties. It also shows robust photothermal performance and strong photocatalytic reactive oxygen species (ROS)‐generation ability. Fe‐BOS@C/H Gel is subsequently prepared by crosslinking hydrazide‐modified chondroitin sulfate, the Fe‐BOS NFs, and oxidized hyaluronic acid via a dynamic Schiff reaction. Fe‐BOS@C/H Gel not only shows good hemostasis and injectability, but also achieves 97% methicillin‐resistant Staphylococcus aureus (MRSA) biofilm elimination. Transcriptomic analyses reveal that Fe‐BOS@C/H Gel operates through multiple antibacterial mechanisms, including the destruction of bacterial membranes and the regulation of oxidative stress pathways and metabolic networks. In vitro cell experiments show that Fe‐BOS@C/H Gel promotes cell proliferation and migration. In a mouse model of MRSA biofilm‐infected wounds, Fe‐BOS@C/H Gel under NIR light eliminates MRSA biofilm through localized high temperature and ROS storms, and promotes collagen deposition and angiogenesis without NIR light. This study provides an innovative solution that utilizes the synergistic strategy of “light‐driven antibacterial performance and pro‐regeneration” to treat drug‐resistant bacterial‐infected wounds.

The nanohybrid hydrogel (Fe‐BOS@C/H Gel) is composed of Fe‐Bi2O2‐XS (Fe‐BOS) photocatalysts and CS‐ADH/OHA (C/H) hydrogel. Fe‐BOS photocatalysts achieve near‐infrared (NIR) light‐driven antibacterial photocatalytic/mild photothermal therapy (APCT/MPTT), effectively eliminating methicillin‐resistant Staphylococcus aureus (MRSA) biofilms. The degradation products of C/H Gel (chondroitin sulfate/hyaluronic acid) promote cell proliferation, accelerate angiogenesis, and accelerate collagen deposition in the absence of light. Fe‐BOS@C/H Gel exhibits a “NIR light‐driven antibacterial‐promoting regeneration” synergistic therapy, accelerating the healing of MRSA biofilm‐infected wounds.