Xinyu Sun

The deterioration of wound microenvironment, bacterial infection, excessive inflammation, impaired angiogenesis and the loss of extracellular matrix are the key obstacles of wound treatment. We develop a “all-in-one” hydrogel wound dressing integrating the functions of photothermal-cinnamaldehyde synergetic antibacterial, antioxidant, anti-inflammatory and good biocompatibility. First, chitosan-tannic acids block copolymers (CS-TA BCPs) with excellent antibacterial and antioxidant functions are fabricated through the molecular self-assemble strategy. CS-TA BCPs provide two cross-linking sites for zinc acetate (ZA) to trigger the gelation driving force between CS and ZA, and induce the ionic chelation interaction between TA and ZA, for producing CS-TA nano-gel particles (NGPs), which are used for stabilizing CA-loaded Pickering emulsions (CS-TA-CA PEs). Further, combining CS-TA-CA PEs, poly-dopamine (PDA), and through the calcium ions (Ca2+) in-situ exchange strategy from sodium alginate (SA)-calcium carbonate hybrid system, a new type of green and biocompatible PEs/PDA/SA hydrogel with photo-thermal, antibacterial, controlled release CA, antioxidant and anti-inflammatory multiple functions is designed. The PEs/PDA/SA hydrogel can clean the wound microenvironment, resist bacterial invasion, reduce inflammatory response, restore the immune function of damaged tissues, promote cell proliferation and tissue regeneration, and effectively accelerate the healing of S. aureus-infected wounds, showing a great application prospect in the biomedical field.

Hydrogel materials have proven valuable in wound healing, but improving the safety of these hydrogels is still challenging. Therefore, designing multifunctional natural polymeric-based hydrogels with excellent mechanical properties to replace toxic or potentially risky, refractory chemical polymer-based hydrogels such as polyacrylamide and polyethylene glycol is of particular significance. Here, a green starch-based hydrogel (Starch@Ca/CGC hydrogel) with injectability, self-healing, and instant adhesion was constructed by coordination interaction, electrostatic interaction, and intramolecular and intermolecular hydrogen bonds. Therein, natural bioactive small molecules gallic acid (GA) and carvacrol (CA) were coordinated with metal ions by the ultrasonic-triggered self-assembly and ionic cross-linking codriven strategy to prepare Cu-gallic acid-carvacrol nanospheres (CGC NPs), which conferred the hydrogel with near-infrared light (NIR)-controlled CA release and photothermal synergistic sterilization properties, as well as antioxidant and anti-infection capabilities. More importantly, the multifunctional hydrogel platforms could completely cover an irregular wound shape to prevent secondary injury and significantly accelerate wound healing under NIR with more skin appendages like hair follicles and blood vessels appearing. Therefore, it is expected that this starch-based hydrogel could serve as a competitive multifunctional dressing in the biomedical field, including bacteria-derived wound infection and other tissue repair.