The Study On Electrochemical Deposition Of Salicylate Derivatives To Improve Biological Performance Of Stainless Steel Surface

The medical 316 L stainless steel has been widely used as implant devices materials, such as vascular stent, artificial joints due to the excellent mechanical properties. However, the hemocompatibility of these biomedical metals is insufficient for the long-term corrosion resistance and antithrombogenic demand in vivo applications. So the methods on improving the properties of surface of medical metallic materials are attracting attention of researchers. Salicylic acid, as a derivative of phenol, researchers pay little attention to its similar property of the electro oxidative polymerization like phenol. In this paper, three different salicylate derivatives were respectively synthesized through the reactive carboxyl group of salicylic acid: dextran salicylate(DEX-S), poly(2-hydroxyethyl methacrylate-glycidyl methacrylate- salicylate)(PHEMA-GMA-S) and β-cyclodextrin salicylate(β-CD-S). The electrodeposition of the derivatives onto the surface of 316 L stainless steel to improve the properties of stainless steel, such as corrosion resistance,biocompatibility, blood compatibility, were studied. The main work as follows:The methyl salicylate was electrodeposited on the surface of stainless steel foil by the anodic electrooxidation polymerization. FT-IR spectra were applied for verifying the existence of the electrodeposited methyl salicylate layer on the SS surface. Tafel plots and EIS technologies were used to estimate the corrosion resistance of salicylate-modified stainless steel. The modified stainless steel exhibited better corrosion resistance and hydrophoic than the virgin one..The surface properties of the stainless steel were modified by dextran on the purpose of corrosion resistance and hemocompatibility for the biomedical application. Biocompatible and poor soluble dextran was coupled with salicylate by transesterification in DMSO in one step. And then the dextran-salicylate was electrodeposited on the surface of stainless steel foil by the anodic electrooxidation polymerization of the salicylate. 1H NMR spectrum was used to determine thestructure of the compound and its degree of substitution. FT-IR spectra were applied for verifying the dextran-salicylate and the existence of the electrodeposited layer on the SS surface, respectively. Tafel plots and EIS technologies were used to estimate the corrosion resistance of dextran-modified stainless steel. The dextran-modified stainless steel exhibited better hemocompatibility compared with unmodified counterpart in the processes of BSA adsorption test, platelet adhesion test and hemolytic test.The surface properties of the stainless steel were modified by PHEMA on the purpose of corrosion resistance and hemocompatibility for the biomedical application. The PHEMA-GMA-S copolymer was synthesized by precipitation polymerization in ethyl acetate and then coupled with salicylic acid by ring opening reaction of epoxy group. Molecular weight and distribution of polymer before and after reaction by gel permeation chromatography(GPC). The grafting rate of PHEMA-GMA-S was calculated by ultraviolet spectrum. The copolymer was immobilized on the surface of stainless steel foil by the anodic electrooxidation polymerization of the salicylate. FT-IR and UV spectra were applied for verifying the p HEMA-GMA-SA copolymer and the existence of the electrodeposited layer on the SS surface, respectively. Tafel plots and EIS technologies were used to estimate the corrosion resistance of p HEMA-modified stainless steel. The hemocompatibility of p HEMA-modified stainless steel was determined by BSA adsorption, platelet adhesion and hemolytic test.The surface properties of the stainless steel were modified by β-cyclodextrin(β-CD) on the purpose of corrosion resistance and drug release for the biomedical application. Biocompatible and poor soluble β-CD was coupled with salicylate by transesterification in DMSO in one step and then the β-cyclodextrin-salicylate(β-CD-S) was electrodeposited on the surface of stainless steel foil by the anodic electrooxidation polymerization of the salicylate. 1H NMR spectrum was used to determine the structure of the β-CD-S compound and its degree of substitution.FT-IR spectra were applied for verifying the synthesized β-CD-S and the existenceof the electrodeposited layer on the SS surface, respectively. Tafel plots and EIS technologies were used to estimate the corrosion resistance of β-CD-covered stainless steel. Chloramphenicol was selected as a model drug in this paper.Electrochemical quartz crystal microbalance(EQCM) was applied for determining the drug adsorbability of the stainless foil before and after modification. E. coli was selected as a harmful microbe to evaluate the antibacterial properties of the stainless steel foil samples with the comparison of optical density(OD) values.