Surface Modification Of Medical Interventiongal Catheter Polypropylene For Improvement Of Hydrophilicity And Biocompatibility

Surface hydrophilicity of interventional catheter is an important property for clinical application since it will directly affects lubricity and blood compatibility of interventional catheter. However, surface hydrophilicity is always decided by surface characteristics, so surface modification is a useful method to improve hydrophilicity. Polyvinylpyrrolidone (PVP) is a water-soluble polymer and it can form hydrogel by hydrogen bond complexation with water, so PVP is often used to modify the material surface to improve the hydrophilicity.The research described in this paper presents three kinds of surface modification method of polypropylene(PP) which are completely physical coating of PVP, plasma pre-modification combined with physical coating of PVP, and plasma grafting of PVP.With the decreased degree of water contact angle as the evaluation standard, the plasma treatment parameters were optimized. The final paramenters were argon flow was 80 sccm, treatment time was 10 minute, and power was 100 W. It was also decided that optimal concentration of PVP was 2%, and PVP molecular weight was 360,000.Based on the result of water contact angle, completely physical coating of PVP was proved to be inefficient because there was only van der waals force between PVP and PP, and this interaction was too weak to have the good binding force.The analysis of attenuated total reflection fourier transform infrared spectroscopy (FTIR-ATR) indicated that the chains of PVP had successfully coated or grafted onto the PP surface by plasma pre-modification combined with physical coating of PVP and plasma grafting of PVP. The result of X-ray photoelectron spectroscopy (XPS) showed that the peak of N_1s appeared in two kinds of modified surface and this also showed that the PVP chains were introduced onto the PP surface. Curve fitting of XPS indicated that content of nitrogen element on the two kinds of modified PP surface. The stability of PVP on the modified surface on the water was investigated, and the result displayed that the content of oxygen and nitrogen on the modified by plasma pre-modification combined with physical coating of PVP decreased, but the content of carbon, oxygen and nitrogen on the samples modified by plasma grafting of PVP kept stable. This could be explained by the different existing ways of PVP moleculaes on the diffferent modified surface. The interaction of PVP molecules with the surface modified by plasma pre-modification combined with physical coating of PVP was van der waals force and hydrogen bond, and this interaction is relatively weak, so some of PVP molecules were dissolved after being immersed in water. The interaction of PVP molecules with the surface modified by plasma grafting of PVP was chemical bonding, and this interaction is stronger, so PVP molecules could stably exist in the water.The evaluation of blood compatibility and endothelial cells adhesion illustrated that the anticoagulant property and endothelialization on the surfaces of PP modified by plasma grafting of PVP and plasma pre-modification combined with physical coating of PVP were both improved, but the former was superior. The results of in vitro platelet adhesion test and lactic dehydrogenase(LDH) test showed that the numbers of adhered platelets were less and the activation of platelets degree was lower on PP surface modified by plasma grafting of PVP compared with PP surface modified by plasma pre-modification combined with physical coating of PVP. The adhesion and proliferation of endothelial cells were better on the PP surface modified by plasma grafting of PVP, and this was probably because PVP chains were grafted onto PP effectively by plasma grafting. The grafted PVP chains could form hydrogel with water and change microdynamics environment between blood and material, which could inhibit adhesion and activation of platelets. This good hydrophilicity was beneficial to adhesion and proliferation of endothelial cells.