E-mail address:ishihara @bmw.mm.t.u-tokyo.ac.jp (K.
Preparation and performance of protein-adsorption-resistant
asymmetric porous membrane composed of polysulfone/phospholipid polymer blend
Takashi Hasegawa ,Yasuhiko Iwasaki ,Kazuhiko Ishihara *
Department of Materials Science,Graduate School of Engineering,The Uni v ersity of Tokyo,7-3-1Hongo,Bunkyo-ku,Tokyo 113-8656,Japan Institute of Biomaterials and Bioengineering,Tokyo Medical and Dental Uni v ersity,2-3-10Kanda-surugadai,Chiyoda-ku,Tokyo 101-0062,Japan
Received 15March 2000;accepted 11May 2000
To obtain protein-adsorption-resistant membrane for hemodialysis,we prepared a polymer blend composed of polysulfone and 2-methacryloyloxyethyl phosphorylcholine (MPC)polymer (PSf/MPC polymer).The content of the MPC polymer in the PSf was 7and 15wt%.The asymmetric porous membrane was obtained by the dry/wet membrane processing method.The surface characterization of the PSf/MPC polymer membrane by X-ray photoelectron spectroscopy revealed that the MPC polymer located at the surface.The mechanical strength of the PSf/MPC polymer membrane did not change compared with that of the PSf membrane.On the other hand,the permeability of solute below a molecular weight (Mw)of 2.0;10 through the PSf membrane increased with the addition of the MPC polymer,which is considered to be an e !ect of the hydrophilic character of the MPC polymer.The amount of protein adsorbed on the PSf membrane from plasma was reduced by the addition of the MPC polymer.The permeability of low-molecular-weight protein (Mw "1.2;10 )did not change even after the PSf/MPC polymer membrane was contacted with plasma protein solution for 4h,whereas it decreased dramatically in the case of the PSf membrane.Platelet adhesion was also e !ectively suppressed on the PSf/MPC polymer membrane.Based on these results,the MPC polymer could serve as a doubly functional polymeric additive,that is,to generate a protein-adsorption-resistant characteristic and to render the membrane hydrophilic. 2000Elsevier Science Ltd.All rights reserved.
Keywords:Hemodialysis;Polysulfone;Blood compatibility;2-Methacryloyloxyethyl phosphorylcholine;Polymer blend;Doubly functional polymer
Polysulfone (PSf)is widely used as one of the poly-meric materials for manufacturing hollow "ber mem-branes for hemodialyzers 。The PSf can be formed as an asymmetric membrane with a skin layer,which deter-mines the permeability for solutes,and a porous struc-ture as a support。Therefore,the PSf membrane has both good permeability for solutes including low-molecular-weight ((2;10 )proteins and good mechanical strength。However,when the PSf membrane contacts the whole blood,protein adsorption occurs on the surface of the membrane and causes serious problems,i。e。,a de-crease in the permeability of the membrane and clot
formation.When the hemodialysis membranes,including the PSf membrane,are used clinically,infusion of an anticoagulant into the patient is required.If the adsorp-tion of the protein on the surface of the hemodialysis membrane could be inhibited,these serious problems will be solved at the same time,and steady and safe hemodialysis treatment will be realized.Therefore,we tried to prepare a novel material for making the hemodialysis membrane with a protein-adsorption-resistant surface using the PSf as a base material.
Many studies have been reported to modify the surfa-ces of the biomedical devices with other polymers by physical adsorption,graft polymerization,or interpenet-rated network formation.To obtain excellent biocom-patible and blood compatible surfaces,we considered that a biomembrane-like structure made by the arrangement of the phospholipid polar groups may be a good technique.Thus,we synthesized polymers having a phospholipid polar group in the side chain,
0142-9612/01/$-see front matter 2000Elsevier Science Ltd。All rights reserved。PII:S 0142-9612(00)00180-0