| Burn and scald refers to the tissue damage caused by physical and chemical factors,which is a common trauma in daily life.In the process of wound healing,zinc has the functions of hemostasis,inflammatory response regulation,and promotion of epithelialization,so as to accelerate wound healing.Epidermal cell growth factor(EGF)is a kind of bioactive peptides,it has also been used in the treatment of various wounds in recent years,in the process of wound repair,EGF can promote epithelial cells and fibroblasts proliferation,promote angiogenesis and adjust the role of inflammation,in the treatment of burns and scald,there are few reports on the preparation of topical preparations by combining zinc with EGF.In order to prepare an easy to use,safe and effective preparation with natural antibacterial activity for the treatment of skin scald of animals,the commonly used chitosan and poloxamer were used as gel materials,and zinc gluconate and recombinant human epidermal cell growth factor(r EGF)were added to prepare a thermo-sensitive hydrogel dressing,by investigating prescription gel preparation,quality evaluation,in vitro antibacterial effect in vitro and effects of bacterial biofilm,the curative effect of scald rats and stimulating,so as to the clinical research lay the foundation for the treatment of burns.1.By preparing rat skin second-degree scald model,using the software Image J to calculate the skin wound area,comparing the skin wound shrinkage rate at different time,by skin wound shrinkage rate to evaluate the treatment effect of gel on scald skin in each group,the prescription of temperature sensitive gel was obtained:the chitosan concentration is 2%,poloxamer 407 concentration is 23%and poloxamer 188concentration is 3%,the zinc gluconate concentration is 0.5%and the recombinant human epidermal cell growth factor is 20μg/ml.2.It was found by direct contact in vitro bacteriostatic experiment that the prepared temperature-sensitive gel had delicate texture and was light yellow.It was in the state of flowing liquid at room temperature and gelation at body temperature.No stratification was observed after centrifugation at 3000r/min for 30min,with good uniformity and good moisturizing effect within 12h.The gelling time of the temperature sensitive gel was about1.6min,the gelling temperature was about 33℃,and the PH value of the gel was between4.5 and 5.0.Through to the gel in vitro dissolution and in vitro release experiments of the r EGF,found within 6 h gel in vitro dissolution rate of 95%,r EGF in vitro release rate of80%,the accumulative release rate of r EGF(X)the cumulative dissolution rate of gel(Y)mapping,regression equation is obtained for Y=1.3826 X-0.0471(R~2=0.9952),its linear relationship,good show that drug release is closely related with the dissolution of the gel.3.Preparation by in vitro bacteriostasis experiment found that the temperature-sensitive gel on E.coli,Staphylococcus aureus and Pseudomonas aeruginosa has inhibition.The effect of the prepared thermo-sensitive gel on bacterial biofilm was investigated by crystal purple staining,it was found that the zinc gluconate/r EGF chitosan thermo-sensitive gel also inhibited the formation of biofilm of single and mixed strains of staphylococcus aureus and pseudomonas aeruginosa,the gel with microbial cultivation for24h,the inhibition rate of Staphylococcus aureus biofilm formation and Pseudomonas aeruginosa biofilm formation were 89.51%and 75.87%respectively,the hybrid strains of bacterial biofilm formation inhibition rate was 79.12%;In addition,it also has a scavenging effect on the bacterial biofilm that has been formed,and the gel acts with the biofilm that has been formed for 24h,the removal rate of the biofilm of staphylococcus aureus was 59.10%,that of pseudomonas aeruginosa was 81.97%,and that of the mixed biofilm of the two strains was 94.29%.4.By scald rat model,the skin wound shrinkage rate at different treatment time was calculated,The kit was used to determine the content of alkaline phosphatase(APK)in serum and HYP,il-6 and TGF-β1 in skin tissue of scald rats at different sampling times.The results show that,in the treatment of 21 d,the skin wound shrinkage rate of three groups of chitosan temperature sensitive gels containing zinc gluconate,r EGF and zinc gluconate/r EGF reached 93%,and the separate temperature-sensitive chitosan gel group(do not take drugs)and model group(do not do any processing)of the skin wound shrinkage rate is approximately 85%,drug-loading show that chitosan temperature-sensitive gel to scald rats cure effect is better;The three groups of chitosan thermperature-sensitive gels added with drugs can increase the hydroxyproline(HYP)content of skin tissues and promote the healing of skin wounds.Chitosan thermperature-sensitive gel with zinc gluconate can increase the content of alkaline phosphatase(APK)in the serum of scald rats to a certain extent and supplement the zinc demand during wound healing.Chitosan temperature-sensitive gels with recombinant human epidermal growth factor(r EGF)were shown to reduce IL-6 levels and increase TGF-βcontent in skin tissues prior to treatment.5.The male New Zealand white rabbit was used as the experimental animal of skin irritation experiment,and the irritation experiment of normal skin and’#’skin injury was carried out.The experiment result expresses the normal skin and’#’damaged skin were consistent with the normal saline control group after continuous application of the drug for7 days,indicating that the drug-loaded chitosan temperature-sensitive gel had no irritation to the damaged skin and normal skin and was safe to use.Zinc gluconate/r EGF chitosan temperature sensitive gel was successfully prepared in the artical,and the experiments of pharmacodynamics experiment and and the skin irritation were carried out.In this paper,The gel prepared has a good antibacterial effect in vitro,and has a good inhibitory effect on escherichia coli,staphylococcus aureus and pseudomonas aeruginosa,effective treatment of scalded rats,and no irritating to the skin,for clinical treatment of burn preparation development provides a new way of thinking. |
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