Alginate Cryogels for Rapid Hemostasis and Toluidine Blue-Mediated Photodynamic Inactivation of Bacteria

The development of new wound dressings with fast hemostatic and bactericidal properties for prehospital care is critical. Antibacterial photodynamic therapy (aPDT) has attracted attention due to its broad-spectrum antibacterial activity and minimal bacterial resistance. However, photosensitizers used in aPDT often face issues such as poor water solubility, short-lived singlet oxygen (¹O₂), and limited ¹O₂ diffusion range. In this study, sodium alginate was covalently modified with the photosensitizer toluidine blue O (TBO) and phenylboronic acid (PBA). The modified alginate was then cross-linked with Ca(II) ions and lyophilized to form a cryogel, named SA@Ca(II)@TBO@PBA (SCTP). This cryogel functions as an antibacterial photodynamic wound dressing. The chemical immobilization of TBO and PBA enhanced the cryogel's targeting ability. PBA formed reversible covalent bonds with diol groups on bacterial cell surfaces, allowing the cryogel to capture bacteria effectively and enhance aPDT. The bactericidal efficiency of the cryogel was tested through in vitro antibacterial assays, and its hemostatic properties were confirmed in vivo. The results indicate that this cryogel has excellent hemostatic and antibacterial capabilities, showing great promise as a wound dressing for clinical applications.