Surface Modification And Cytocompatibility Of Biomimetic Silk Fibroin Artificial Ligament Materials

The artificial ligament woven with polyester fiber has played an important role in clinic,but because of its non-degradability and biological inertia,it is prone to fatigue relaxation,instability of knee joint and poor healing of tendon and bone.Therefore,a kind of silk fibroin artificial ligament material with bionic and degradable structure was designed and prepared by referring to the structure of human knee anterior cruciate ligament.Moreover,the cell compatibility was further improved by surface modification,which laid a foundation for the regeneration of ligament tissue in vivo.The main contents of this study include: 1.Design the silk fibroin artificial ligament material with bionic structure,and prepare the braided "shell" artificial ligament material(B-AL)and woven "shell" artificial ligament material(W-AL)by combining different textile forming methods.2.Two methods were used to modify the surface of silk fibroin artificial ligament materials.One was direct chemical grafting of protein(EDC/NHS),the other was low temperature oxygen plasma combined with chemical grafting(O2 & EDC/NHS).Collagen I(Col I),human fibrinogen(Fg)and transforming growth factor TGF-?1 binding peptide(Pep)were grafted onto the surface of silk fibroin artificial ligament materials and characterized.3.Before and after the surface modification,human skin fibroblasts(HFF)and mouse fibroblasts(L929)were inoculated on the surface of the material.The cell compatibility of the materials were characterized,and the cell growth,distribution and collagen secretion were investigated.The main results and conclusions of this study are as follows:1.The artificial ligament material based on silk fibroin has degradability,controllable shape,structure,scale and good mechanical properties.It is feasible to prepare the artificial ligament material with "shell-core" structure by covering the collagen fiber structure with the fascia of bionic natural ligament tissue.2.The tensile breaking strength of W-AL reached 1284.4±72.7 N and 77.3 ± 4.4 MPa.This is twice the value of anterior cruciate ligament(38.0±9.0 MPa).The mechanical properties of W-AL are better than those of B-AL.3.After surface modification,the micro morphology of fibroin fiber artificial ligament materials changed,but the overall structure of fibroin was retained;the water contact angle became smaller,the hydrophilicity was improved;the mechanical properties of the modified materials decreased,but the overall mechanical properties of the ligament materials were not affected.4.The biocompatibility of silk fibroin artificial ligament materials were improved by surface modification.Cells can enter the pores of materials for growth and proliferation,and secrete collagen at the same time.Compared with the two modified methods,the cells proliferated better on the materials modified by O2 & EDC/NHS.The HFF had higher activity on SF-O2-Fg,while the L929 had better proliferation on SF-O2-Col I.This shows that different cells have different response to materials.In a word,the silk fibroin artificial ligament materials with bionic structure,controllable size and excellent mechanical properties were prepared by using natural silk as raw material.After surface modification,the cell compatibility was improved,which can provide reference for the development of artificial ligament with high strength,degradability and good cell compatibility.