| The skin is the largest organ of the human body.It has multiple functions and plays an important role in human body temperature regulation,body fluid balance maintenance,immune barrier,etc.A healthy and intact skin is important for maintaining the body's physiological balance.However,the skin is in direct contact with the external environment,it is easy to be injured and produce defects and form acute wounds.If the wound cannot heal in time,it may develop into a chronic wound that is more difficult to treat.On the other hand,with the aging of the population and the increase in the incidence of some diseases related to the formation of chronic wounds,the number of chronic wound patients has increased sharply.Therefore,it is of great significance to develop a dressing that can accelerate wound healing.The use of electrically active dressings to promote wound healing is the focus of the field of wound dressing research.However,the existing electroactive dressing has a complicated preparation process and high cost,and biotoxic reagents are also used in the preparation process.In order to solve this problem,we proposes a simple,efficient,and biocompatible preparation method for electroactive dressings.In this thesis,the gauze was modified for conductivity,and a chitosan(CS)drug-loaded conductive dressing was prepared by electrophoretic deposition.It is expected that the antibacterial ability and electrical activity of the dressing will act synergistically to promote wound healing.The main research contents and conclusions are as follows:(1)The electrophoretic deposition kinetics of CS and the preparation of CS conductive dressing.Firstly,polypyrrole(PPy)is polymerized on the surface of the gauze to prepare the conductive gauze,and then the conductive gauze is used as the electrode,and the CS hydrogel coating is constructed on the surface of the conductive gauze by electrophoretic deposition in the CS electrolyte.The effects of voltage and Na Cl concentration in the electrolyte on the deposition behavior of CS were studied,and the optimal process parameters for electrophoretic deposition of CS were optimized:the deposition voltage was-3 V,and the concentration of Na Cl in the electrolyte was 10 m M.Under the optimal parameters,the deposition rate of CS hydrogel is faster,and it is easy to maintain a complete structure.The control effect of Na Cl concentration in the electrolyte on the structure and performance of CS hydrogels was studied.The results showed that the pore diameter and porosity of CS hydrogels increased with the increase of Na Cl concentration in the electrolyte,which in turn affected the swelling properties and hydrophilic and hydrophobic properties of CS hydrogels.The conductivity of the prepared chitosan conductive dressing is between 1.0×10-2 S/cm and 2.4×10-2S/cm,and it has good electrical activity.(2)The preparation of CS drug-loaded conductive dressing and its drug controlled release behavior.Ciprofloxacin hydrochloride(CIP)and chitosan were co-deposited into the dressing to prepare CIP/CS/PPy/cotton gauze dressing.The effect of drug concentration on drug loading rate and encapsulation rate was studied,and the controlled release behavior of the dressing under different p H conditions and different electrical signal input conditions was explored.The results showed that with the increase of the drug concentration in the electrolyte,the drug loading rate increased from rapid to slow,and the encapsulation rate first increased and then decreased.The drug loading performance was better when the concentration of ciprofloxacin hydrochloride was 9mg/m L.The drug release rate of the drug-loaded dressing under acidic environment is significantly greater than that under neutral and alkaline conditions,and the dressing exhibits a p H-responsive drug controlled release behavior.When a voltage of+3 V is applied to the dressing,the release of the drug can be promoted.On the contrary,when a voltage of-3 V is applied,the release of the drug can be inhibited.The drug release behavior of the dressing is responsive to electrical signals.(3)Research on the biological properties of CS drug-loaded conductive dressings.The antibacterial properties,blood compatibility and cytotoxicity of the dressings were studied.The full-thickness wound model of bacterial infection was constructed,and the wound healing effect of dressings was verified in vivo.The results showed that the drug-loaded dressing has significant antibacterial effect and can effectively inhibit the growth of Escherichia coli and Staphylococcus aureus.The dressings has excellent blood compatibility and low cytotoxicity,and its hemolysis rate is less than 2%.It did not show obvious cytotoxicity in the 5-day cell proliferation experiment.Chitosan drug-loaded dressings can promote blood coagulation through endogenous pathways.In in vivo experiments,the CIP/CS/PPy/cotton gauze dressing has a promoting effect on wound healing,especially in the early stage of wound healing,it can effectively inhibit bacterial infection and reduce wound inflammation. |
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