Preparation Of A Beta-tricalcium Phosphate Nanocoating By Electrophoretic Deposition And Its Protein Adsorption Behaviour

Beta-tricalcium phosphate(?-TCP),with excellent biocompatibility and biodegradability,has been extensively applied inorthopaedics as implant materials.Proteins in surrounding body fluids of implanted biomaterials are rapidly adsorbed on the surface.The protein adsorption layer on the surface affects the subsequent interaction of cells with the implant material and the biomineralization process.The interaction between materials and proteins has become one of the hot topics in the field of biomaterials.Thus far,most of the work concerned the study on adsorption behaviour of a small number of single proteins on material surface.The body fluids contain a large number of proteins.Different kinds of proteins compete for adsorption on the surface of materials and interact with the surface of the materials,thus affecting the cell adhesion behavior and mineralization behavior on the surface of the materials.In this paper,the adsorption behaviors of single bovine serum albumin(BSA)and single lysozyme(LSZ)on the surface of ?-TCP and the competitive adsorption behaviors between them on the surface of ?-TCP were studied by using quartz crystal microbalance with the dissipation(QCM-D),and the mechanism was also studied.First,the electrophoretic deposition(EPD)was used to prepare the ?-TCP nanocoating on Au surface for QCM-D,and the influence of the electric field intensity,deposition time and additive on the preparation of the nanocoating were investigated.The results show that the size and quantity of particles on the coating surface increased along with the increase of the electric field intensity,and the surface roughness also increased.The size and quantity of particles and the surface roughness increased along with the increase of deposition time,but the deposition rate decreased along with the prolongation of the deposition time.With the addition of trace hydrochloric acid in the suspension,the conductivity of the suspension increased significantly,the aging time shortened significantly,and the deposition rate decreased more obviously along with the prolongation of the deposition time.The best condition of the preparation of ?-TCP nanocoating for QCM-D was the electric field intensity of 25 V/cm and the deposition time of 5 min.The adsorption behaviors of single BSA and single LSZ with different concentrations on the surface of ?-TCP were studied by QCM-D.It is found that the adsorption capacities of BSA and LSZ increased with the increase of the concentration of protein solution,and the adsorption processes were basically not affected by the concentration of protein solution.The adsorption behaviors of BSA and LSZ on the same surface were different,which was mainly due to the differences in protein properties.The differences in adsorption capacities of BSA or LSZ on the different material surfaces mainly due to the different properties of material surfaces,especially the difference of surface potential.The competitive adsorption behaviors of BSA and LSZ on the surface of ?-TCP were studied by QCM-D.The results show that BSA could replace the LSZ adsorbed on the material surfaces,and the substitution rate increased with the increase of the BSA concentration;LSZ could not replace the BSA adsorbed on the material surfaces,and the higher concentration of the LSZ also not replaced BSA.This was mainly due to the fact that BSA has more action sites with materials than LSZ.When BSA and LSZ were simultaneously contained in the solution,they were adsorbed on the material surface in the form of BSA-LSZ,which was mainly due to the opposite charge of the two proteins in the solution.