Immobilization Via Polydopamine Of IGF-1/BMP-2 Dual Growth Factors On Polyetheretherketone:Improvement Of Cell Adhesion,Proliferation,and Osteo-differentiation

Polyetheretherketone(PEEK)is a promising biomedical material in orthopedic and dental applications owing to its excellent mechanical properties,near absent immune toxicity,and X-radiolucency,but suffers from bio-inertness and inferior osteoconduction.Surface modification of PEEK can effectively solve this problem,retaining most of its advantageous properties.The main aim of this study is constructed a bioactive surface on PEEK implants through surface modification.In this study,surface 3D porous structure was fabricated by immersed in concentrated sulfuric acid and washed by distilled water.Then,IGF-1/BMP-2 dual growth factor was immobilized onto the porous structure through an intermediate layer of p DA to construct a bioactive PEEK implants.At the first part of this study,the surface morphological characteristics,porous size distribution,surface elements,hydrophilic,immobilization efficiency of growth factor and tensile mechanical properties of the modificated PEEK implants was systematic evaduated.The results of our study indicated: 1)the surface porous structure with most of the pores size distributed between 0.24 ?m and 0.74 ?m and 3.5 ?m thick was fabricated on PEEK implants by immersed in concentrated sulfuric acid according to the analysis using SEM and Image J software;2)XPS analysis showed that very few of SO3 H group was introduced onto the surface of PEEK implants after immersed in concentrated sulfuric acid.The peek of N element demonstrating p DA was successfully coated onto the surface of PEEK implant;3)the hydrophobicity of the PEEK implants coud be decrease by the surface porous structure,while p DA coating could significantly improve the hydrophobicity of the samples;4)surface p DA coating could allow greater protein adsorption capacity of the samples;5)the analysis of ELISA easy showed that,quantitative of immobilized IGF-1 on PEEK-P/p DA was 7.82 ng,43.94 ng,and 86.54 ng for the corresponding treatment concentrations of 10 ng/ml,50 ng/ml,and 100 ng/ml,respectively.The amount of BMP-2 immobilized onto PEEK-P/p DA was 8.02 ng,48.16 ng,and 91.86 ng for the corresponding treatment concentrations of 10 ng/ml,50 ng/ml,and 100 ng/ml,respectively;6)the excellent bone like elastic modulus property of PEEK materials could be preserved by this surface modification approach.However,yield strength was decreased from 100.2 ± 3.8 MPa to 81.9 ± 1.3 MPa after fabricating surface porous structure on PEEK implants and breaking elongation of pure PEEK was reduced from 226.9 ± 4.6 % to 216.1 ± 2.5 % after the porous fabricating process.In the second part of the studies,in vitro study was employed.The influence of varying doses of IGF-1 or BMP-2 on MC3T3-E1 cell proliferation was explored in order to determine the suitable dosage for application in subsequent dual growth factor combining utilization experiments.The doses of 50 ng/ml IGF-1 and 50 ng/ml BMP-2 could efficiently endow PEEK with improved bioactivity.The comparison of cell adhesion,proliferation,extracellular matrix secretion and osteo-differentiation on the IGF-1/BMP-2 dual loaded samples and other samples was estimated.The result of our study showed: 1)surface 3D porous structure could improve bioactive to some extent;2)surface p DA coating could be used either as immobilizated interface layer of IGF-1/BMP-2 and could enhance the bioactive of PEEK implants;3)the decoration of single BMP-2 could significant enhance adhesion,spreading,extracellular matrix secretion and osteo-differentiation of MC3T3-E1 cells.However,it showed no significant difference for the cell proliferation;4)samples decorated with single IGF-1 could enhance adhesion,spreading,proliferation,extracellular matrix secretion and osteo-differentiation of MC3T3-E1 cells.However,the ability of the single IGF-1 for the cell adhesion and osteo-differentiation was lower than BMP-2;5)samples decorated with IGF-1/BMP-2 dual growth factor could significantly enhance MC3T3-E1 cell adhesion,spreading,proliferation,extracellular matrix secretion and osteo-differentiation compared with other groups.In conclusion,surface 3D porous PEEK implants decorated with IGF-1/BMP-2 dual growth factor via p DA coating could significantly improve the hydrophobicity,protein adsorption capacity and bioactive of the PEEK implants.MC3T3-E1 cell adhesion,spreading,proliferation,extracellular matrix secretion and osteo-differentiation was significantly enhanced,a larger amount of bone tissues around the implants and robust bone-implant bonding in vivo was expected,and the the failure of the implant after implantion would be reduced.