Multifunctional sodium alginate injectable hydrogel based on intelligent cascade dynamic regulation (ICDR) of ROS...

Hydrogel dressings play a crucial role in promoting the healing of wound microenvironments associated with drug-resistant bacterial infections. Herein, a multifunctional injectable hydrogel diagnostic platform (CCAS) was developed based on an intelligent cascade dynamic regulation (ICDR) for reactive oxygen species (ROS) response therapy and inflammation visualization. The strong hydrogen bonding interactions between the natural biopolymer sodium alginate (SA) and the photosensitizer coumarin-based (CCA) improved the solubility of coumarin and improved the mechanical properties of the hydrogel. The three-dimensional network structure of the hydrogel locked the water through hydrogen bonding to maintain a moist environment of the wound, accelerating the migration of epithelial cells and collagen deposition, and avoiding dehydration and crusting due to traditional dressings. Upon blue light irradiation, CCAS generatesd substantial amounts of ROS, demonstrating remarkable antibacterial efficacy against Methicillin-Resistant Staphylococcus aureus (MRSA) and ESBL-producing Escherichia coli (ESBL-E.coli) via photodynamic therapy (PDT), with antibacterial efficiencies reaching 99.94 % and 98.31 %, respectively. Upon removal of external stimulus, CCAS effectively scavenged excess ROS and promoted the differentiation of macrophages into the M2 phenotype, thereby downregulating inflammation levels, reducing pro-inflammatory factors, promoting angiogenesis, and ultimately achieving a healing efficiency of up to 93.60 %. Furthermore, CCAS could monitor inflammation levels in real time by detecting H₂S levels at the wound site, assessing the inflammatory recovery status effectively. This versatile hydrogel system establishes a foundation for next-generation smart wound dressings with dual therapeutic-diagnostic capabilities.