Plasma-surface Modification Of Polysulfone Membrane And Its Application In Membrane Type Oxygenator

Artificial lung,also referred to as membrane oxygenator or gas exchange device,is commonly used in cardiopulmonary bypass of thoracotomy to support life,during which it expels the CO2 generated in the metabolic process from the body and takes in necessary O2.Generally,an eligible artificial lung has very stringent requirements on gas permeability and blood compatibility.In this thesis,polysulfone(PSF)hollow fiber membrane was selected as basement membrane for oxygenator and was prepared by optimizing experimental condition.Acrylic acid(AA)-heparin,phosphorylcholine(MPC)and collagen were firstly grafted onto the surface of PSF membrane by low temperature plasma technology to improve its biocompatibility,and gas transfer capability have reached the standard of commercial artificial lung,which have provided technological foundation for the development of industrialization.1.Preparation and optimization of PSF hollow fiber membraneIn this study,the nonsolvent-induced phase separation was used to produce PSF hollow fiber membrane.To optimize polysulfone concentration,coagulation bath temperature and dry-spinning distance,porosity of membrane was measured to verify it,and results showed that the gas flux and porosity optimized when polysulfone concentration was 15%,coagulation bath temperatures was 50℃ and dry-spinning distance was 1 cm.Then influences of PEG with different molecular weight were used as additive were investigated by SEM,porosity,gas flux and contact angles Results shows that the hydrophily of membranes was improved when PEG was added.The cross-section was sponge structure and the porosity and gas flux optimized when the molecular weight of PEG was 1000.2.Grafting of AA and heparin on the surface of PSF membraneAA and heparin were grafted onto the surface of PSF membrane by low temperature plasma technology for the first time.Fourier transform infrared spectroscopy(FTIR)and X-ray photoelectron spectroscopy(XPS)were used to verify the results of plasma modification.The optimal hydrophilicity of the PSF-AA membrane was achieved.by being treated by low temperature plasma technology with Ar as gas source,microwave power of 40 W,treatment time of 50 s,total gas flow rate of 40 4mL/min,exposure time in air of 5 minutes as well as AA concentration of 70%.Also experiments of bovine serum albumin adsorption and platelet adhesion showed significant improvement of PSF-AA-Hep membranes in hemocompatibility.Pure gas permeation test and gas-liquid transport experiments showed that PSF-AA-Hep membranes retained excellent performance compared with PSF membranes.When the flow rate of pig blood reached 5 L/min,the permeation fluxes of O2 and CO2 were 192.6 mL/min and 166.9 mL/min respectively,which were close to the gas exchange transmission standard of membrane oxygenator.3.Grafting of MPC on the surface of PSF membraneMPC were firstly grafted onto the surface of PSF membrane by low temperature plasma technology.FTIR and XPS were used to verify the results of plasma modification.The optimal grafting degree of the PSF-MPC membrane was achieved.by being treated with grafting concentration of 3%as well as grafting temperature of 40℃.Also experiments of bovine serum albumin adsorption and platelet adhesion demonstrated significant improvement of PSF-MPC membranes in hemocompatibility Pure gas permeation test and gas-liquid transport experiments showed that PSF-MPC membranes retained excellent performance compared with PSF membranes.When the flow rate of pig blood reached 5 L/min,the permeation fluxes of O2 and CO2 were 196.3 mL/min and 172.5 mL/min respectively,which were close to the gas exchange transmission standard of membrane oxygenator.4.Grafting of collagen on the surface of PSF membraneCollagen were grafted onto the surface of PSF membrane by low temperature plasma technology for the first time.FTIR were used to verify the results of plasma modification.Meanwhile,experiments of bovine serum albumin adsorption and platelet adhesion exhibited certain improvement of PSF-Col membranes in hemocompatibility.The grafting degree test and pure gas permeation test showed that the optimal grafting condition was being treated with grafting concentration of 20 g/L as well as grafting temperature of 40℃.Pure gas permeation test and gas-liquid transport experiments showed that gas flux of PSF-Col was decreased.When the flow rate of pig blood reached 5 L/min,the permeation fluxes of O2 and CO2 were 148.1 mL/min and 120.2 mL/min respectively,which were lower than gas exchange transmission standard of membrane oxygenator.