NIR/glucose stimuli-responsive multifunctional smart hydrogel wound dressing with NO/O2 dual gas-releasing property promotes infected diabetic wound healing

It is still challenging to design stimuli-responsive smart hydrogel dressing to promote bacteria-infected diabetic wound healing from the whole healing stage by intelligently responding to external stimuli or wound microenvironment. In addition, nitric oxide (NO) and oxygen (O2) have been shown to accelerate diabetic wound healing by promoting angiogenesis and alleviating hypoxia. A series of NIR/glucose stimuli-responsive multifunctional smart hydrogels with NO/O2 dual gas-releasing properties was designed based on N-carboxyethyl chitosan-grafted-phenylboronic acid (CECP), oxidized dextran (OD), ε-polylysine (EPL)-coated manganese dioxide (EMn), and β-cyclodextrin-reduced graphene oxide/N, N'-di-sec-butyl-N, N'-dinitroso-1,4-phenylenediamine (rGB) via dual dynamic crosslinking to promote bacteria-infected diabetic wound healing. The added rGB and EMn as photothermal agents rapidly kill bacteria through photothermal therapy. Meanwhile, rGB endows CECP/OD/EMn/rGB hydrogels to release NO under NIR stimulation to promote angiogenesis. Nanozyme EMn with catalase (CAT)/superoxide dismutase (SOD)-like activity can scavenge ROS and release O2 to alleviate hypoxia and oxidative stress. The phenylboronic acid in CECP forming phenylboronate ester structure endows hydrogel with glucose-controlled release of doxycycline. NIR/glucose stimuli-responsive CECP/OD/EMn/rGB hydrogels with NO/O2 dual gas-releasing property in a full-thickness skin wound-infected diabetic model reduced the inflammation, promoted wound contraction, collagen deposition, angiogenesis, and alleviated wound hypoxia, providing new ideas for treating bacteria-infected diabetic wounds.