Preparation And Characterization Of Antimicrobial Artificial Dermal Scaffold

Objective:Evaluation of the antimicrobial effect of hypertonic sodium solution and gallium ion solution against bacteria encountered in burn wound infection.Preparetion of antimicrobial artificial dermal scaffold to prevent wound infection,providing an experimental foundation for the preparation of related antimicrobial artificial dermal scaffolds,and experimental basis for further study and clinical transformation.Methods:Standard strains of bacteria common in burn wound infections were selected,including Staphylococcus aureus?ATCC25923?,Staphylococcus epidermidis?FSCC223011?,and Enterococcus faecalis?FSCC146002?,and Gram-negative:Escherichia coli?ATCC25922?,Pseudomonas aeruginosa?ATCC27853?,Klebsiella pneumoniae?FSCC167002?,Enterobacter cloacae?FSCC145003?,Acinetobacter baumannii?ATCC19606?,and Stenotrophomonas maltophilia?ATCC51331?.Agar medium plates with different concentrations of sodium ions were prepared,and the antibacterial evaluation of hypertonic sodium was conducted in vitro.The minimum inhibitory concentration?MIC?of gallium nitrate against bacteria that are common in infected burn wounds was determined with a Microbial Viability Assay Kit-WST.The microstructure and morphology of Escherichia coli and Staphylococcus aureus after contact with gallium ion were observed by transmission electron microscope?TEM?.A gallium-loaded antimicrobial artificial dermal scaffold was prepared by gallium ions and collagen solution guided by the bionic design principle,and characterization and biological evaluation in vitro and in vivo was carried out.Alginate was selected as the carrier,and gallium alginate composite carrier and its related dermal scaffold were constructed by several immersion freeze-drying and gelation reactions.The material was characterized and its antibacterial properties were evaluated.Results:The results showed that hypertonic saline solution inhibit bacterial growth including Acinetobacter baumannii,Escherichia coli,Pseudomonas aeruginosa,Enterococcus faecalis,Stenotrophomonas maltophilia when concentration of sodium chloride was 4%,and Klebsiella pneumoniae,Enterobacter cloacae,Staphylococcus aureus,Staphylococcus epidermidis were added to the antibacterial spectrum when concentration reached 8%.The results showed that the MIC of Ga?NO₃?₃ against E.coli and E.faecalis was 256?g/ml,and it was 512?g/ml against P.aeruginosa,K.pneumonia,E.cloacae,A.baumannii,S.maltophilia,S.aureus and S.epidermidis.Meanwhile,transmission electron microscopy?TEM?found similar visual evidence of the mechanism by which the gallium ion attacks both Gram-negative and Gram-positive bacteria,which was in agreement with the MIC results.By TEM observation,it was found that detachment of the cell membrane and wall and the appearance of an electron-light region containing condensed substances occurred in both Ga³⁺-treated E.coli and Ga³⁺-treated S.aureus cells,with smaller morphological changes in Ga³⁺-treated S.aureus compared with E.coli.The characterization results showed a porous structure with pore sizes ranging from 50-150?m and a large porosity value of 97.4%.The enzymatic degradation rate in vitro was 19 and 28%after 12 and 24 h,respectively.In vitro antimicrobial testing revealed that the 1 h antibacterial rate against S.aureus and P.aeruginosa was close to 90%,which indicated its great antimicrobial activity.The results of the cytological evaluation showed no cytotoxicity,with a relative growth rate?RGR?value of 80%and great cytocompatibility with cultured cells according to laser scanning confocal microscopy?LSCM?and scanning electron microscope?SEM?.Furthermore,the successful prevention of wound infections in SD rats was confirmed with an in vivo antimicrobial evaluation,and the artificial dermal scaffolds also demonstrated great biocompatibility.gallium alginate composite carrier and its related dermal scaffolds were successfully constructed by gallium ion solution,alginate and collagen solution,including the dermal scaffold coated with gallium alginate,gallium alginate particles and its composite dermal scaffold.The characterations shows a good three-dimensional pore structure and excellent antibacterial performance.Conclusion:The hypertonic sodium solution has good antibacterial ability against bacteria common in burn infected wound,which can provide a good therapeutic plan for the local treatment of burn infected wound.This research shows the effective and wide-spectrum antimicrobial properties of gallium nitrate against most bacteria encountered in burn wound infections.A gallium-loaded antimicrobial artificial dermal scaffold was successfully prepared,a three-dimensional porous structure,suitable pore size,high porosity,excellent enzymatic degradation performance and gallium ion release were demonstrated,and excellent antimicrobial activity in vitro and in vivo,great biocompatibility and no cytotoxicity were found.This gallium-loaded antimicrobial artificial dermal scaffold could effectively prevent the infection of wounds and implants and warrants further research for future clinical applications.The preparation of gallium ion-related composite carrier and dermal scaffold was preliminarily realized,which provided the experimental basis for the further study of gallium ion releasing carrier.