Preparation And Properties Of Silk Fibroin/Wool Keratin Composite Scaffold

Injury and defects of human organs or tissues caused by congenital defects or infections,trauma and tumor resection induce great pain and burden to patients.It is crucial to develop the repaired materials that meet the requirements of transplantation.Good biocompatibility,biodegradability,uniform pore size distribution and porosity,and excellent mechanical properties are important performance requirements for repair materials.As a natural polymer material,silk fibroin(SF)has good biocompatibility,mechanical properties and biodegradability,and has been used in repair materials widely.The arginine-glycine-aspartate(RGD)tripeptide sequence which can promote the adsorption of cells existing in the amino acid sequence of wool keratin,it has good biocompatibility and promotes cell attachment and growth positively.Recent studies demonstrated that when wool keratin(WK)is added into the SF tissue engineering materials,the ?-sheet structure of SF is more favorable,and the biocompatibility of the composite porous material is improved significantly.In the present work,SF and WK were used as the basic materials,and the double-protein composite porous scaffold was prepared by freeze-drying technology and investigate its physical,biodegradability and biocompatibility,systematically.Firstly,WK solution was prepared using alkaline method and reduction method respectively,and the secondary structure,thermal stability and molecular weight were tested and analyzed.Then,different protein concentrations(6%and 9%)and different protein ratios(SF:WK=10:0,8:2 and 6:4)were selected,and SF/WK composite porous scaffold was prepared by freeze-drying method.,tested the pore size distribution,secondary structure,mechanical properties,thermal stability and water swelling properties of the scaffold.Degradation experiments were performed in PBS buffer and protease XIV solution by selecting three protein ratio scaffolds(protein concentration of 9 wt%).Finally,mouse fibroblasts were cultured in vitro,and the cell proliferation and adhesion on the composite porous scaffold were observed to evaluate the cytocompatibility of the composite porous scaffold material.The results showed that the preparation of WK by the reduction method had higher protein molecular weight and thermal stability,the internal structure was more stable,which was more suitable for the preparation of WK.The SF/WK composite porous scaffold had a stable secondary structure,a suitable internal pore size(?150 ?m)and porosity(?80%),the dry and wet compressive strength were 1.48 ± 0.15 MPa and 0.26 ± 0.04 MPa,respectively.Furthermore,it is of good thermal stability and water-swell ability.The internal pore size,porosity and water-swell ability of the composite porous scaffold increased with the increase of WK ratio(p<0.05).When the WK reached a certain ratio,the composite porous scaffold showed a pore size of above 600 ?m and a porosity rate of above 90%.The SF/WK composite porous scaffold had better compression resilience than the pure SF porous scaffold.By examining the degradation properties of SF/WK composite porous scaffold,it was found that the addition of WK accelerated the degradation of composite scaffolds,and the degradation process was mainly metastable structure(meta-stable structure in SF silk I mainly).The composite porous scaffold was cultured with cells in vitro,and it was confirmed that the addition of WK promoted the growth and proliferation of cells in the scaffold(p<0.05).In summary,the SF/WK composite porous scaffold has good uniform pore size distribution,porosity,mechanical properties,structural stability,degradation performance and biocompatibility,and it has great potential in the application of scaffold materials.