Functional Modification Of Central Venous Catheter And Its Performance Research

With the continuous advancement of medical technology,central venous catheters（CVC）have gradually become one of the preferred tools for implanted medicine.CVC is generally extruded from polyurethane（PU）,and the hydrophobicity of the PU surface may cause serious catheter complications,which restricts its application in the medical field.Many scholars have devoted themselves to the modification of PU,but for anticoagulation and antibacterial properties,more in-depth research is still needed.In this paper,the surface of the polycationic structure was first constructed,and the acryloyloxyethyltrimethylammonium chloride（DAC）and diallyldimethylammonium chloride（DMDAAC）were grafted onto the PU membrane surface by the surface initiated atom transfer radical polymerization（SI-ATRP）.Different cationic quaternary ammonium salts have different graft densities as variables.ATR-FTIR,XPS and WCA were used to characterize the properties of the samples after modification.At the same time,biocompatibility experiments were carried out on PU samples with different graft densities to determine the optimal graft density.The results show that it is feasible to introduce cationic quaternary ammonium salt using SI-ATRP method,and the quaternary ammonium salt effectively improved the wettability of PU.The water contact angle after grafting was reduced by about 30°compared with before grafting,and the modified PU samples became hydrophilic.Different graft densities not only affect wettability,but also have different effects on biocompatibility.When the graft density is low,the biocompatibility will increase with the increase of the cationic graft density.When the graft density is greater than a certain critical value,the positive surface charge attracts protein adsorption,which reduces biocompatibility.Therefore,the graft density should not be too large,and 80-100μg/cm² is more suitable.Secondly,a lubricating surface was constructed,and polyvinylpyrrolidone（PVP）hydrogel was grafted onto the PU membrane surface using a Fenton-like reaction.The effects of different experimental conditions on the amount of surface hydrogel coating were investigated,and the samples before and after modification were characterized using ATR-FTIR,XPS and water contact angle.The friction of the modified PU was investigated,and the performance of the grafted PU was explored through biocompatibility experiments.The results show that when the concentration of the crosslinking agent is 10%,the concentration of PVP is 10%,the concentration of tert-butyl hydroperoxide（TBHP）is 8%,and the concentration of Fe²⁺is 0.1%,the grafting amount of the hydrogel is large.The PVP hydrogel grafted on the PU surface can greatly reduce the water contact angle and friction coefficient of the PU,and the hydrophilicity and lubricity are significantly improved.The biocompatibility of PVP itself does not disappear due to grafting,so that PU has good anticoagulant properties,and different EDGMA concentrations have little effect on biocompatibility.Finally,combined with the above two conclusions,CVC was functionally modified to enhance its dual-antibody performance,using Fenton-like reaction grafted polyvinylpyrrolidone-chitosan（PVP-CS）hydrogel.The effects of different reaction conditions on the amount of hydrogel coating were investigated.SEM,water contact angle test and friction coefficient test were used to compare the changes before and after grafting.The firmness of PVP-CS hydrogel was determined by UV characterization of the soaking solution.The relative molecular weight of PVP will affect the formation of hydrogels,and the effect of biocompatibility is investigated by changing the relative molecular weight of PVP.The results show that when the CS concentration is 1%and PVP（K23-K27）is used,the grafting amount of the hydrogel is optimal.After grafting,the surface morphology of CVC changed,the water contact angle became smaller,the friction coefficient became smaller,and CVC did not fall off after soaking for 3 days.After CVC is coated with PVP（K23-K27）,the biocompatibility is significantly enhanced,and the anticoagulant performance is also greatly improved.