Design And Preparation Of Multifunctional Polymer Hydrogels And Their Application In Chronic Wound Dressings

The nursing and treatment of chronic wound is one of the most intractable problems in clinical skin injury repair.The presence of inflammatory cytokines,high levels of reactive oxygen species(ROS)and protease,and repeated bacterial infections are key factors in the development of chronic wounds.Traditional dry wound dressings,such as gauze,bandages and cotton sheets,can protect the wound and absorb some exudate,but they have many disadvantages that are not conducive to wound healing,such as easy adhesion to the wound,secondary injury caused by dressing change,and failure to prevent infection.With the development of biomedical materials and the deepening of wound healing theory,researchers have found that moist environment is more beneficial to the wound healing.In recent years,hydrogel dressings have attracted extensive attention from researchers because they can provide a moist healing environment for wounds,prevent secondary infection of bacteria,do not adhere to new tissues,and are easy to modify.Taking the polymer hydrogel with good mechanical properties as the main line,this paper is committed to developing new multifunctional hydrogel dressings that can specifically solve the influencing factors of chronic wound healing,and improve the efficiency of wound repair.The specific work is as follows:Firstly,a temperature-resistant antibacterial moisturizing dual network(DN)hydrogel dressing(G-PAGL)with water/glycerol binary solvent was prepared by embedding the inherent antibacterial ε-PL chain segment into a crosslinking network with PAM and GT as the main skeleton structure.The combination of rigid and flexible chain segments gives the hydrogel dressing good mechanical properties.In addition,G-PAGL retains its excellent adhesion over a wide temperature range(-20-60 ℃),as well as its broad and persistent antibacterial activity against E.coli(Gram-negative bacteria)and S.aureus(Gram-positive bacteria).The versatile hydrogel dressing successfully promoted DFUs healing by promoting granulation tissue formation,collagen deposition and angiogenesis,as well as preventing bacterial infection.This work extends the application environment of DFUs wound dressings to extreme temperature conditions,and providing a new option for antimicrobial dressings in clinical application.Secondly,we complex the electroactive substance into the hydrogel system,and design a multifunctional conductive hydrogel patch with adjustable transparency,strong tensile,good adhesion,and rapid hemostasis.A hydrogel patch named P(PyTa)/CHA was prepared by one-step polymerization of acrylamide(AM)and acrylated adenine(Aa)using in situ polytannin-doped polypyrrole P(Py-TA)nanofibers.Notably,when used as wound dressing,P(Py-TA)/CHA hydrogel shows good therapeutic effect on DFUs by enhancing information exchange between cells,rapidly hemostasis,promoting angiogenesis and accelerating collagen deposition.In addition,the smart multifunctional hydrogel patch enables the monitoring of wound healing status through surface electromyography(s EMG)and real-time detection of human movement.This work opens a new way for conducting hydrogel dressings,flexible biological electrodes and adhesive epidermal sensors for biomedical engineering applications.Finally,we further simplified the synthesis of hydrogel,combined the conductive hydrogel with electric stimulation(ES)to prepare an MXene-based "nano-enzyme" autocatalytic multifunctional conductive hydrogel system(PMTA),and explored its promoting effect on infection chronic wound healing.The conductive hydrogel has excellent mechanical properties,good adhesion,effective antioxidant and antibacterial activity.In vivo and in vitro experimental results showed that the combination of conductive hydrogel and ES could significantly promote the collagen deposition,vascularization and epidermal remodeling at the wound site accompanied by the effects of anti-inflammatory,antioxidant and anti-infection,and further accelerate the wound healing.This study provides new potential directions for the design of novel wound dressings and the clinical treatment of chronic infected wounds.