The Design Of Chitosan/silk Fibroin-alginate Laminated Film And Its Biological Evaluation

Background:Because of the special physiological structure of tendon,adhesion with surrounding tissues is often formed after tendon injuries.The repair of tendon injury includes endogenous healing and exogenous healing.The former shows better biomechanical properties and mild dysfunction,and the latter is easier to form scar for the growth of surrounding sheath and synovial membrane,resulting in tendon adhesion.Therefore,it is an reasonable method to prevent tendon adhesion by controlling exogenous healing and promoting endogenous healing.It was reported that alginate(Alg)can inhibit the adhesion of fibroblasts.Silk fibroin(SF)film owns strong mechanical strength and good tissue inducibility,but it is fragile.Chitosan(CS)film has good elasticity,blended with silk fibroin can be prepared a biomembrane with high tenacity.Objective:Preparing a biofilm that can not only promote the repair of tendon,but also inhibit tendon adhesion.Methods:the preparation of chitosan/silk fibroin(CS/SF)hybrid membrane was formed after natural drying.Then the sodium alginate film(Alg)was com’bined on the CS/SF film by coating to prepare the double layer composite membrane.The structure was characterized by infrared spectroscopy(FT-IR).The surface morphology was observed by scanning electron microscope(SEM),and its swelling property,mechanical property,surface hydrophilicity and in vitro degradation property were also detected.The inhibitory effect of A1g membrane on L929 cells and the effect of CS/SF membrane on the tendon cells were evaluated by cytological test.Finally,the CS/SF-Alg membrane was applied to the rat Achilles tendon repair model.Results:FT-IR shows that the mixture of SF and CS promotes the beta folding of silk fibroin,and there is electrostatic adsorption between CS and Alg.SEM shows that the CS/SF membrane has ravine surface morphology and nano mesoporous structure,and the Alg membrane has a loose hydrogel like structure.The mechanical properties test showed that the elongation at break of CS/SF8:2 film reached the maximum value of 46.85%.The tensile strength of CS/SF7:3 film reaches the maximum value of 21.19 Mpa.The hydrophilic test shows that the contact angle of the CS/SF film is about 70°,and the contact angle of the Alg film is also about 70°.The swelling rate CS/SF 3:7 film is about 70%,and the swelling rate of the Alg film is more than 120%.In vitro degradation experiment showed that the residual mass fraction of CS/SF membrane was 82%～85%after 4 weeks.The residual mass fraction of Alg membrane was 55%.Cytological experiments showed that L929 cells were round on the Alg membrane,and the number of cells was less,and the growth of tendon cells on the CS/SF membrane was faster than that of the control group.Cell migration experiments showed that the migration speed of L929 on the CS/SF membrane was faster than that on the CS membrane.After 4 weeks of subcutaneous implantation,the double layer structure of the CS/SF-Alg bilayer was still visible,and there was a light inflammatory reaction in first weeks and then disappeared.Conclusions:A double functional membrane with complex layer structure was prepared by using CS,SF and Alg.It has strong mechanical properties,suitable swelling properties,good hydrophilic property and reasonable degradation performance.Further more,the bilayer film possesses good biocompatibility or histocompatibility.The CS/SF membrane can promote the growth and migration of tenocytes,whereas the Alg membrane is suppressing to fibroblasts.It is potential for the repairing of tendon injuries.