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Conventional wound closure and dressing are two crucial, time-consuming but isolated principles in wound care. Even though tissue adhesive opens a new era for wound closure, the method and biomaterial that can simultaneously achieve noninvasive wound closure and promote wound healing are highly appreciated. Herein, a novel supramolecular poly(N-isopropylacrylamide) hybrid hydrogel dressing composed of quaternized chitosan-graft-𝜷-cyclodextrin, adenine, and polypyrrole nanotubes via host-guest interaction and hydrogen bonds is developed. The hydrogel demonstrates thermal contraction of 47% remaining area after 2 h at 37 °C and tissue adhesion of 5.74 kPa, which are essential for noninvasive wound closure, and multiple mechanical and biological properties including suitable mechanical properties, self-healing, on-demand removal, antioxidant, hemostasis, and photothermal/intrinsic antibacterial activity (higher 99% killing ratio within 5 min after irradiation). In both full-thickness skin incision and excision wound models, the hydrogel reveals significant wound closure after 24 h post-surgery. In acute and methicillin-resistant Staphylococcus aureus-infected wound and photothermal/intrinsic antibacterial activity assays, wounds treated with the hydrogel demonstrate enhanced wound healing with rapid wound closure rate, mild inflammatory response, advanced angiogenesis, and well-arranged collagen fibers. Altogether, the results indicate the hydrogel is promising in synchronously noninvasive wound closure and enhanced wound healing.

Wound with drug-resistant bacterial infections has become a serious challenge for the healthcare system, and designing wound dressing to self-adapt to the need of different stage of wound healing remains challenging. Herein, self-adaptive wound dressings with multiple stimuli-responsiveness and antibacterial activity are developed. Specifically, MoS 2 carrying a reactive oxygen species (ROS) responsive nitric oxide (NO) release precursor L-arginine (MSPA) is designed and incorporated into carboxymethyl chitosan/poly(Nisopropylacrylamide) based cryogels (CMCS/PNIPAM) with multiple responsiveness (pH, near infrared (NIR), and temperature) to form self-adaptive antibacterial cryogels that adapt to the therapeutic needs of different stages in infected wound healing. In response to the slightly acidic environment of bacterial infection, the cryogels assist the bacterial capture capacity through acid-triggered protonation behavior, and effectively enhance the photodynamic antibacterial efficiency. Controllable on-demand delivery of ROS, NO, and remote management of infected biofluid are achieved with NIR light as a trigger switch. The multiple stimuli-responsive nanozyme-based cryogels efficiently eliminate MRSA bacterial biofilm through NO assisted photodynamicand photothermal therapy (PDT&PTT). The multiple enzyme-like activities of the cryogels effectively relieved oxidative damage. Notably, these cryogels effectively reduce wound infection, alleviated oxidative stress, and accelerate collagen deposition and angiogenesis in infected wounds, indicating that multiple stimuli-responsive self-adaptive wound dressings provide new ideas for infected wound treatment.

Wound refers to the place where human body is injured and ruptured. So, wounds in a broad sense include not only skin wounds, but also damages of muscle, corneal, heart, and lung, etc. As "gold standard" of wound closure, suture and staple cause secondary damage to the tissue, and require professional skills and equipment, so noninvasive hydrogel adhesives have been developed as an alternative to close and treat different kinds of wounds. However, the existing reviews mainly discussed the research of hydrogel adhesives for skin wounds, and the focus is mostly on its types and adhesion mechanisms, but a review comprehensively discusses the design and application of hydrogel adhesives on generalized wounds for wound closure and wound healing and the unique needs of various wounds for hydrogel adhesives is still lacking. In this review, the types and adhesion mechanisms of hydrogel adhesives will be briefly described, then the research progress of hydrogel adhesives in wound treatment is reviewed in detail from two aspects: the comprehensive design principles and the unique requirements of different types of wounds. Overall, we expect that this review will provide guidance for the development of hydrogel adhesives as new avenues for generalized wound care and treatment.

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