Protoporphyrin IX-modified chitosan/sodium alginate based cryogels for rapid hemostasis and antibacterial photodynamic therapy of infected wound healing

Due to the porous and interconnected structure, cryogels significantly facilitate blood exudate absorption and support rapid hemostasis as novel wound dressings. However, cryogels suffer from insufficient inherent antibacterial properties, which seriously limits their clinical applications. Herein, we developed a chitosan (CHI) and sodium alginate (SA) composite-based antibacterial photodynamic therapy (aPDT) cryogel for rapid hemostasis and infected wound healing. In this cryogel, the photosensitizer protoporphyrin IX (PpIX) was chemically immobilized onto CHI (CHI-PpIX), while the phenylboronic acid (PBA) molecules were coupled onto SA (SA-PBA). The resulting CHI-PpIX/SA-PBA (CPSP) hydrogel was created by mixing CHI-PpIX and SA-PBA, followed by freeze-drying to form the CPSP cryogel. Through forming dynamic boronic ester bonds between PBA and diol groups on bacterial cell walls, CPSP was endowed with bacterial capturing capacity and enhanced aPDT. In vitro antibacterial experiments revealed its enhanced aPDT efficiency owing to PBA-mediated bacterial targeting. In addition, in vivo assays demonstrated its effective hemostatic, antibacterial and wound healing-promoting capacities. By effectively integrating aPDT with bacterial capturing capabilities and addressing the limitations of existing wound dressings, the CPSP cryogel offers a promising solution for rapid hemostasis and the treatment of infected wounds.