Surface Modification Of Polysulfone Membrane By Low Temperature Plasma And Its Application In Membrane Oxygenator

Artificial lung, also referred to as membrane oxygenator or gas exchange device, is used routinely in cardiopulmonary bypass during thoracotomy to support life. Generally, an eligible artificial lung should at least be able to transport gas well and be biocompatible. Currently, physical or chemical methods have been developed to change the surface properties of materials to improve their biocompatibility. In this thesis, polysulfone(PSF) membrane prepared under optimum conditions was selected as basement membrane for oxygenator. Polyethylene glycol(PEG), heparin, acrylic acid(AA) and polyethylene glycol acrylate(PEGA) were grafted onto the surface of PSF membrane by low temperature plasma technology to improve the biocompatibility. Besides, the results were compared.1. Grafting of PEG and heparin on the surface of PSF membranePEG with different molecular weights and heparin were grafted onto the surface of PSF membrane by low temperature plasma technology. Firstly, the influences of power, treatment time, flow rate of gas and gas type on the material surface modification and blood compatibility were studied. The hydrophilicity of modified PSF membrane was optimized by being treated for 2 min with Ar at 150 W. Then, the influence of molecular weight of PEG was studied. PSF-PEG6000-Hep membrane adsorbed minimum amounts of bovine serum albumin and blood platelets. The modified membrane retained good performance of PSF basement membrane. As suggested by the gas-liquid transport experiments through PSF-PEG6000-Hep membrane oxygenator. When the flow rate of pig blood reached 1.5L/min, the permeation fluxes of O2 and CO2 were 110ml/min and 102ml/min, respectively, which were close to the gas exchange transmission capacity of membrane oxygenator.2. Grafting of PEG and heparin on the surface of PSF membraneAcrylic acid was grafted onto the surface of PSF basement membrane by plasma grafting and plasma polymerization. Grafting was performed in both solution and vapor phase. For the grafting in solution, the influences of temperature and concentration of acrylic acid solution on the material surface property were studied. With 40wt% acrylic acid solution at 60℃, the hydrophilicity of the membrane was obviously augmented and the bovine serum albumin adsorption was significantly reduced, with the adhesion of considerable platelet though. Meanwhile, it was difficult to control the degree of polymerization of acrylic acid. And the gas flux of the membrane grafted in solution was significantly decreased in the presence of over-polymerized acrylic acid. Moreover, in the gas-liquid transport experiments, the permeation fluxes of O2 and CO2 were only 70.36mL/min and 62.79mL/min when the flow rate of pig blood reached 1.5L/min. In contrast, grafting in vapor phase gave satisfactory transmission performance by remedying the deficiency of that in solution.3. Grafting of PEGA and heparin on the surface of PSF membranePEGA was grafted onto the surface of PSF membrane by low temperature plasma technology, yielding a highly hydrophilic and biocompatible modified membrane. By containing double bonds, PEGA was grafted onto the PSF membranes more readily compared to polyethylene glycol was. Therefore, it is reasonable to predict that the PEGA-modified PSF membranes are potentially applicable to the biomedical field. The effects of temperature and concentration of PEGA solution were also studied. When the content of PEGA was 50g/L, the modified membrane had the lowest contact angle, and the amounts of adsorbed bovine serum albumin and adhesive platelets significantly decreased. The permeation of modified membranes was close to that of the basement membrane.