Preparation Of Amphiphilic Amino Acid Modified Polyvinylidene Fluoride Membrane And Its Blood Compatibility Study

Polyvinylidene fluoride(PVDF)is widely used for blood purification and filtration.However,due to the hydrophobic PVDF membrane,it is easily adsorbed proteins and its poor hemocompatibility is not completely thrombosis resistant and needs to be improved for more demanding biomedical applications.Grafting modification is a common method to improve the he mo co impa t ib il it y PVDF membrane,but the existing grafting modification only can form a single lager.Because of the limited grafting density,we try to build the complex structure zwitterions as functional layer on the membrane surface in a efficient and convenient way.Herein,we aim to graft zwitterions onto PVDF membranes through two routes as follows:(1)PVDF membrane was pretreated with sodium hydroxide for introducing carbon-carbon double bond.And then,a cross-linked hydrogel was grafted on the membrane surface.Finally,zwitterionic cysteine(Cys)was grafted by an interfacial polymerization based on the thiol-epoxy ring-opening between diethylene glycol dialycigyl ether(PEGDG)and Cys.(2)PVDF membrane was pretreated with sodium hydroxide for introducing carbon-carbon double bond.Then,hyperbrached polymer was polymerized on the surface of PVDF membrane for forming a hyperbranched carbon-carbon double bond layer via ATRP method.Followed by Michael addition reaction,Lysine(Lys)is fixed on the surface of PVDF membrane.The structure and hydrophilic property of grafted membrane were characterized by attenuated total reflection Fourier transform infrared spectroscopy(ATR-FTIR),water contact angle measurement(WCA),and X-ray photoelectron spectroscopy(XPS).The antifouling property of grafted membrane was studied by static protein adsorption experiment and dynamic protein pollution test.The biological properties of the membrane were studied by platelet adhesion test,red blood cell adhesion test and anticoagulant test.The results showed that the anion acid successfully grafted on the PVDF membrane surface.Compared with pristine PVDF membrane,the PVDFA-g-Cys and PVDFA-g-Lys membranes showed better hydrophilicity,more negatively charged surface,low lower protein adsorption,and better suppressed platelet adhesion and red blood cell adhesion.Furthermore,the increase of activated partial thromboplastin time(APTT)and Thrombin time(TT)indicated that hemocompatibility of the PVDFA-g-Cys and PVDFA-g-Lys membranes had been improved.In this workp the zwitterionic amino acid with good hemocompatibility was successfully grafted on the PVDF membrane surface,which provided a reliable basis for further study of zwitterionic modified separation membrane materials.