Development And Study Of Zwitterionic Hydrogel Wound Dressings

Skin traumas are among the most common health problems in the world.It has been attracting great attentions to develop wound care management and wound dressing materials.Traditional dressings such as bandages and gauze are typically made of dry cotton,which can protect the wound and absorb exudate.However,these dry dressings might impede the wound healing process due to their intrinsic limitation.With the development of wound healing theory and biomedical materials,it has been found that wet dressings can provide a moist environment for better healing.Here,based on the concept of moist wound healing and hydrophilic anti-biofouling zwitterionic material,we designed a series of zwitterionic hydrogel wound dressings and investigated their effect on both acute and chronic wound healing to achieve ideal wound dressings.In this work,we used zwitterionic hydrogel as wound dressing for the first time and evaluated its effect on burn wound treatment.PHEMA,PCB and PSB hydrogels were synthesized and compared with a commercial product-Duoderm^?.Results showed that PCB hydrogel based dressings with a high water content could provide a moist environment for wound healing,and enhance epithelialization while avoiding wound adhesion.The burn wound healing rate was promoted by 1/3 compared with that of Duoderm^?dressing.Moreover,we modified the two most commonly used dressings,gauze and bandage pads with zwitterionic hydrogels for convenient storage,handling,and application.These prepared forms could efficiently prevent the contamination of protein,cell,blood and avoid wound adhesion.Bacterial invasion is an essential factor resulting in wound infection and healing delay.Zwitterionic materials are well known for their excellent anti-biofouling properties to resist the bacterial attachment and adhesion,but antimicrobial ability is still needed to avoid/treat infections.Via a one-step in situ photopolymerization reaction,Ag NPs and the PCB hydrogel were formed simultaneously.Results showed that the resulting PCB-Ag NP hydrogel(formed with10 m M Ag NO₃)could effectively kill both E.coli and S.aureus bacteria while maintaining a satisfactory cytocompatibility.More importantly,in vivo tests revealed that it could efficiently treat S.aureus wound infection,promote epithelial regeneration and complete the healing process within two weeks.In this thesis,we also developed and synthesized a class of new antibacterial agents(Ga PP and Ga MP)with dual antibacterial functions.Via combining the porphyrin derivatives with Ga,the new regents could kill bacteria by photodynamic therapy as well as the strategy of Ga to interdict the Fe metabolism.Results showed that compared with the groups without photodynamic treatment,the antibacterial efficiency was enhanced by?2000 fold towards E.coli and?200 fold towards S.aureus.Aimed to solve the halt or deceleration problems in diabetic wound healing,a multifunctional zwitterionic hydrogel was developed to simultaneously detect two fluctuant wound parameters,p H and glucose level,to monitor the diabetic wound status.A p H indicator dye(phenol red)and two glucose sensing enzymes,glucose oxidase(GOx)and horseradish peroxidase(HRP),are encapsulated in the PCB hydrogel matrix.Results show that the activity and stability of both two enzymes are improved within PCB hydrogel,and the K_cat/K_m value of PCB-GOx and PCB-HRP is?5.5 fold and?1.7fold of free HRP in artificial wound exudate,respectively.This novel wound dressing can successfully monitor the p H range of 4-8 and glucose level of 0.1-10 m M.The visible images were collected by a smartphone and transformed into RGB signals to quantify the wound parameters non-invasively and could also promote the diabetic wound healing.