Surface Modification Of Biomedical Materials And Their Biocompatibility Evaluation

The Layer-by-Layer self-assembly (LBL) of polycations and polyanions into multilayers has emerged as an efficient, versatile, and simple method to create biologically active surface. By controlling the assembling condition and the bioactive molecules used, biomaterials' surfaces with required biological activities can be obtained. The LBL technique has been recognized as an important means in the modulation of the surface properties of biomaterials. In this paper, LBL self-assembly method has been integrated with other surface modification methods like atmospheric plasma treatment and biomineralization to satisfy the biocompatibility requirements of different biomaterials in different applications. The following are the main results:1) A biomacromolecular Layer-by-Layer self-assembly process of chitosan/heparin onto both 316L bare-metal stent and repamycin eluting stent is designed for the acceleration of the re-endothelizlization and healing process after coronary stent deployment. The cytocompatibilities and blood compatibilities of both kinds of stents were improved by the LBL process. The combination of LBL self-assembly and asymmetric rapamycin/PLGA coating contributed to a new generation of drug-elution stent aiming at rapid re-endothelialization which could provide protection against thrombus-formation as well as minimizing restenosis. From the vitro haemocompatibility evaluation and arteriovenous shunt model, the new drug-elution stent showed well anticoagulation effects. Both of the rapid re-endothelization and minimizing restenosis effects have been proven from the histological analysis and SEM analysis results from animinal experiments.2) Atmospheric plasma treatment and LBL self-assembly of chitosan/heparin was combined to modify the surface of PTFE artificial blood vessel. After the plasma grafting of different silane coupling agents, amino-group was coupled onto the PTFE surface. The biomacromolucular layer-by-layer self-assembly of chitasan/heprain was also used to obtain a pro-endothelialization and anticoagulation surface. The modified surface was characterized with FTIR. The improvement of cytocompatibility and blood compatibility had been proven by the vitro endothelial cell culture and haemocompatibility evaluation..3) Chitosan/hyaluronic acid layer-by-layer coating was applied on clinically used PET artificial ligament as the template to inspire the biomineralization of calcium phosphate, for the improvement of its osteoconduction. Firstly, PET surface was modified with atmosphere plasma/silane coupling agent and chitosan/hyaluronic acid LBL coating. Then calcium pohsphate was deposited onto the PET surface through the biomineralization process. FTIR results confirmed the grafting of silane coupling agent and the LBL coating on the PET surface. EDX and XRD results gave evidence of the PET surface mineralization with calcium pohsphate. The improvement of PET surface osteoplast affinity by the biomineralization process was proven by the vitro cell culture of MC3T3. These results gave confidence to the future animal experiments of the novel artificial ligament with better healing between ligament-bone.