# Magnesium phosphate mineralized Ce6 composite hydrogel with photodynamic therapy-mediated antibacterial, anti-inflammatory, and pro-angiogenic properties for application in infected wound healing

## TL;DR

A new hydrogel dressing uses light to kill bacteria and speed up wound healing by combining a photosensitizer with magnesium phosphate nanoparticles.

## Contribution

A novel mineralization approach encapsulates Ce6 in magnesium phosphate nanoparticles for sustained photodynamic therapy and wound healing.

## Key findings

- CMP/Gel generates reactive oxygen species to effectively eradicate bacteria upon light irradiation.
- Mg2+ ions released from CMP NPs reduce inflammation and promote angiogenesis and cell proliferation.
- In vitro and in vivo experiments confirm CMP/Gel's efficacy in accelerating infected wound repair.

## Abstract

Wound infection remains a significant clinical challenge, exacerbated by the growing prevalence of bacterial resistance due to the overuse of conventional antibiotics. Photodynamic therapy (PDT) offers a promising approach for wound sterilization that circumvents the issue of antibiotic resistance. However, conventional photosensitizers are prone to inactivation and exhibit poor retention at the wound site, limiting their clinical efficacy. To overcome these limitations, we developed a biomimetic mineralization approach to encapsulate the small-molecule photosensitizer chlorin e6 (Ce6) within magnesium phosphate nanoparticles (CMP NPs), preserving its photodynamic activity. This mineralized CMP NPs were further integrated with gelatin and natural moisturizing factor to fabricate a composite hydrogel dressing (CMP/Gel) for infected wound healing. Gelatin functions as a structural matrix that prolongs the local retention of CMP NPs, while the natural moisturizing factor enhances the hydration capacity and mechanical integrity of the dressing. Notably, magnesium ions released during the degradation of CMP NPs contribute to accelerated wound healing through multiple therapeutic effects, including antioxidant, anti-inflammatory, and pro-angiogenic activities following PDT-mediated bacterial eradication. Both in vitro and in vivo experimental results demonstrate that CMP/Gel effectively promotes infected wound repair, highlighting its potential as a novel and multifunctional therapeutic strategy for infected wound management.

Herein, we report a novel composite hydrogel dressing (CMP/Gel) for the treatment of infected wounds. Upon light irradiation, CMP/Gel generates a substantial amount of reactive oxygen species (ROS) to achieve efficient bacterial eradication. Concurrently, the sustained release of Mg2+ ions during nanoparticle degradation contributes to accelerated wound repair by mitigating residual oxidative stress, promoting cell proliferation and migration, and stimulating angiogenesis. Therefore, the CMP/Gel hydrogel dressing represents a promising and multifunctional therapeutic strategy for infected wound management, with high translational potential.Image 1