Construction Of The Materials Surface Microenvironment Based On ATRP And Its Effects On Cell Behavior

Research background: The ultimate goal of designing biomedical materials for tissue engineering is to prepare scaffolds with suitable biomechanical and biological activity to enable cells have better proliferation,adhesion and differentiation.Therefore,it is very important to construct the microenvironment of materials surface which can support cell growth and differentiation on that.There are many researches to study the interaction of intercellular matrix(ECM)and intercellular,we know that the chemical properties,physical properties and microscopic topologies contained in the extracellular matrix microenvironment have important effects on cell behavior.However,due to the complexity of cell microenvironment,it has hindered people’s understanding of the mechanism of the material surface properties on cell behavior.In recent years,the development of nanotechnology,photolithography and surface induced free radical polymerization(ATRP)has provided a possibility for the construction of bionic surfaces with limited physical or nano patterns.Research objectives: This study will examine the change of cell behavior which affect by the thickness of polymer brushes and RGD modification on the material surface.And we explored that how these two factors affect the different cells which is in different stages of chondrogenic differentiation.We hope this study can be used in the surface modification and clinical application of tissue engineered biological scaffolds.Research methods: This study will design and construct two kinds of material surface microenvironment.By controlling the time of polymerization,we prepared the PHEMA polymer brush with controllable thickness on the surface of glass.Then GRGDS polypeptides were modified on the surface of PHEMA polymer brush by esterification and click chemistry.At last,bone marrow mesenchymal stem cells(BMSC),a chondrogenic progenitor cell(ATDC5)and human chondrocytes(HC)were used to the cell test.The differences in cell proliferation,adhesion and differentiation of these three kinds of cells on the surface of PHEMA polymer brushes with different thickness and on the surface of GRGDS polypeptide were studied.The relationship among the RGD modification,the cell adhesion molecules and the chondrogenic differentiation were discussed.Results: the results of material analysis show that the thickness of PHEMA polymer brush increases with the increase of polymerization reaction time;the change of the thickness of PHEMA polymer brush leads to the change of the modulus of elasticity of the surface,and the thicker the PHEMA polymer brush,the smaller the elastic modulus of the surface,The diversity of composition,wettability and roughness of different thickness PHEMA polymer brush is not significant;the length of PHEMA polymer brush is long,and the thickness is more favorable to the reaction of GRGDS peptide modified with alkynyl,and the clicking efficiency is higher.The cell test results show that the cell culture cells on the thin PHEMA brush surface will promote the spreading of cells and the synthesis of actin fibers.The cell morphology of the cells in the thicker PHEMA polymer brush surface is more round,and the response of the cell to the thickness of the PHEMA polymer brush varies in different stages of chondrogenic differentiation,The adhesion morphology of the HC cells with the PHEMA polymerized brush changes obviously,and high expression of FAK and Integrin beta 1 adhesion molecules on the surface of the thinner PHEMA brush,and the high expression of Sox9 and Col2 cartilage related specific genes in the thicker PHEMA brush surface cells,which is more conducive to the induction of cartilage differentiation and the maintenance of cell phenotype.PHEMA polymer brush surface modified RGD has greater effect on cell proliferation than thickness of PHEMA bursh inhibitory effect on cell proliferation.After grafting RGD polypeptide,the morphology of the cells on the surface of the polymer brush will tend to be more spreading and multi angle,the cell spreading area is increaseing,the adhesion ability is increaseing.The RGD polypeptides from polymer brushes may help cells better perceive the thickness of polymer brushes,thereby regulating cell differentiation.The above results can further understand the effect of surface properties of materials on cell behavior,and provide theoretical guidance for the construction of microenvironment of tissue engineering biomaterial surface.