Construction Of Antibacterial Hydrogels Based On Engineered Photothermal Bacteria For Infected Wounds Healing

Skin wound infection is a common condition caused by the invasion of skin tissue by microorganisms such as bacteria,viruses and fungi.In recent years,researchers have begun to explore and develop a new type of antibacterial material for skin wounds to deal with the problems of traditional treatment methods.Such materials should possess good biocompatibility,biodegradability,and antibacterial properties to promote skin wound healing and repair.Microorganisms have become potential therapeutic agents or drug delivery vehicles due to their living characteristics.Using synthetic biology technology to synthesize engineered bacteria and endow them with photothermal effects,the modified microorganisms are encapsulated in hydrogel as a"living material",which can be used to treat diseases such as skin wound infections and tumors.However,photosensitive bacteria still face some challenges,including single and easily attenuated photothermal effect,high bacterial dose or radiation intensity due to low photosensitizer loading,and the need for multiple irradiations to achieve photothermal therapy.The aim of this study is to prepare a"living"photothermal bacterium-based multiple joint protein water by combining photothermal therapy（PTT）with photodynamic therapy（PDT）and chemical dynamics（CDT）of engineered photothermal bacteria.Gel antibacterial materials to improve their antibacterial performance,biocompatibility and stability,and explore their application prospects in the field of skin wound treatment.The specific work is as follows:1.Construction of antibacterial hydrogels based on engineered photothermal bacteriaThe Escherichia coli BL21 strain expresses melanin（Mel）through genetic engineering,which has a certain PTT effect under laser irradiation and has good photothermal stability.Tetramethylpyridine porphyrin（TMPy P）with PDT properties is selected to generate singlet oxygen（¹O₂）to kill bacteria.As a raw material for CDT,laccase（Lac）not only has good enzymatic activity when immobilized in the hydrogel environment,but also generates reactive oxygen species（ROS）by catalyzing lignin in an aerobic environment.As a protein,bovine serum albumin（BSA）is not only an enzyme stabilizer,but also has abundant amine groups to form protein hydrogel（Gel）by reacting with glutaraldehyde through Schiff base.In addition,a series of characterizations were performed on the properties of the materials,and multiple joint antibacterial effects based on photothermal,photodynamic and chemical dynamics could be achieved.The effect of the hydrogel in the repair of infected wounds was further evaluated through in vitro and in vivo experiments.2.Antibacterial hydrogels for antibacterial in vitro and for repairing infected wounds.Multiple joint antibacterial protein hydrogels exhibited excellent antibacterial activity against Gram-negative and Gram-positive bacteria.In the mouse skin wound infection model,compared with the control group,the healing rate of the wound area was more than that of the control group.After 12 days,only 7%of the wound area in the combined antibacterial group was 38%higher than the 45%in the control group,indicating that the combination The antimicrobial group had the best effect on the bacterial treatment of the mouse wounds.Histological analysis of the wound skin revealed more neogranulation,hair follicles,collagen deposition,and thicker epithelium.It shows that the hydrogel has strong advantages in wound healing treatment of skin infection.The biosafety of the hydrogel was also evaluated.In vitro,the MTT experiment proved that the combined antibacterial hydrogel has good biocompatibility.In vivo,no abnormalities and inflammation were found in the heart,liver,spleen,lung,and kidney of the experimental group of mice,which proved that the hydrogel The gel has good biological safety and wide application prospects.