Surface Engineering Of Spongy Bacterial Cellulose Via Constructing Crossed Groove/column Micropattern By Low-energy Co2 Laser Photolithography Toward Scar-free Wound Healing

Objective:Skin is the bigest defense system of human body,it is easy to be invaded and form wounds,such as:abrasions,burns,stab wounds,lacerations,etc.The original collagen fiber and the skin tissue is absent when damage stimulus reach the dermis and below it.Subsequently,it will cause slow healing of the wound,wound infection,and the formation of scar tissue after healing,which will have adverse consequences for the patient’s image and psychology.Therefore,it is extremely important to the earlier use of materials with good biocompatibility and antibacterial,which can provide an advantage for the rapid healing of wounds.However,the formation of scar tissue after healing is not aesthetically pleasing.How to make the newly formed tissue can simulate the original skin tissue structure is a big problem.In recent years,biomaterials have attracted much attention because of their good biocompatibility,and their degraded products are harmless to the body and can even be utilized by the body.As a low-cost,high-yield,non-toxic and harmless material,the use of the bacterial cellulose can also be expanded by physical and chemical modification.The article main discuss the way to achieve wound-free scar healing.Methods:The bacterial cellulose membrane（BC）was formed by G.xylinus（ATCC 700178）is cultured in static medium.The BC material is a porous network biomaterial under the scanning electron microscope（SEM）,the freeze-dried sample can be burned under the high energy laser etching.So the low-energy（10W）CO₂ laser etching machine is used to form a regular pattern structure.Micropatterned bacterial cellulose（MPBC）film has a regular columnar structure and a vertical and horizontal gullies with certain width and depth.Applying the targeted immobilization of a tetrapeptide consisting of Arginine-Glycine-Aspartic acid-Serine（H-Arg-Gly-Asp-Ser-OH,RGDS）as a fibronectin onto the column platform surface.Material characterization of RGDS-MPBC can be confirmed by SEM,3D scanning,infrared,and contact angle（CA）test.The difference is significant compared to materials without modified and unattached RGDS.In vitro and in vivo experiments were used to further confirm the effect of micropatterning and binding of bioactive fibronectin to the surface of BC material on fibroblasts and skin wound healing.Results:Culturing one week,a porous network BC film is formed above the Acetobacter xylinum culture solution.A crossed groove/column micropattern was constructed on BC using low-energy CO₂ laser lithographytechnology.Applying the targeted immobilization of atetrapeptideconsistingofArginine-Glycine-Asparticacid-Serine（H-Arg-Gly-Asp-Ser-OH,RGDS）as a fibronectin onto the column platform surface,the resulting micropatterned BC（RGDS-MPBC）exhibited dual affinities to fibroblasts and collagen.Material characterization of RGDS-MPBC revealed that the micropattern was built by the column part with size of¹00×100μm wide and¹00μm deep,and the groove part with size of¹50μm wide.Cell culture assays revealed that the RGDS-MPBC exhibited an improved cytotoxicity to mouse fibroblasts L929,as compared to the pristine BC.Furthermore,it was observed that the RGDS-MPBC was able to guide the orderly aggregation of human skin fibroblast（HSF）cells on the column platform surface.Over time,it was found that a dense network of collagen was gradually established across the groove channels.Furthermore,the in-vivo animal study preliminarily demonstrated the scar-free healing potential of the micropatterned BC materials.This RGDS-MPBC material exhibited potential in guiding cell migration and collagen distribution.Conclusion:As a potential wound dressing,the surface hydrophobic properties of the MPBC material increase after low-energy laser etching,which is not conducive to cell adhesion and growth.After RGDS combined,the hydrophilic properties of the material are improved and the migration and proliferation of the cells can be guided.So the RGDS-MPBC material is benefical to the wound healing,which could present a prospect in the establishment of“basket-woven”organization of collagen in normal skin tissue against the formation of dense,parallel aggregation of collagen fibers in scar tissue toward scar-free wound healing outcome.