Poly(hydroxyethyl methacrylate-co-methacrylamidoalanine) membranes and their utilization as metal-chelate affinity adsorbents for lysozyme adsorption

Different adsorbents have been reported in the literature for protein purification. The authors have developed a novel and new approach to obtain high protein adsorption capacity utilizing a 2-methacrylamidoalanine-containing membrane. Amino acid ligand 2-methacrylamidoalanine (MAAL) monomer was synthesized using methacryloyl chloride and alanine. Poly(2-hydroxyethylmethacrylate-co-2-methacrylamidoalanine) [p(HEMA-co-MAAL)] membranes were then prepared by UV-initiated photopolymerization of HEMA and MAAL in the presence of an initiator (azobisisobutyronitrile, AIBN). The synthesized MAAL monomer was characterized by NMR. p(HEMA-coMAAL) membranes were characterized by swelling studies, porosimeter, SEM, FTIR, and elemental analysis. These membranes have macropores in the size range of 5-10 μm. Cu(II) ions (25.9 mmol/m²) were chelated on these membranes. p(HEMA-co-MAAL) membranes were used to study the adsorption of lysozyme from aqueous media containing different amounts of lysozyme (0.1-3.0 mg/l) and at different pH values (4.0-8.0). The non-specific adsorption of lysozyme on the pHEMA membranes was negligible (0.9 μg/cm²). Incorporation of MAAL increased the lysozyme adsorption significantly up to 2.96 mg/cm². The lysozyme adsorption capacity of the Cu(II) incorporated membranes (9.98 mg/cm²) was greater than that of the p(HEMA-co-MAAL) membranes. More than 90% of the adsorbed lysozyme was desorbed in 1 h in the desorption medium containing 1.0 M NaCl and 0.025 M EDTA. The metal-chelate affinity membranes are suitable for repeated use for more than ten cycles without a noticeable loss of capacity.     

Poly(hydroxyethyl methacrylate-co-methacrylamidoalanine) membranes and their utilization as metal-chelate affinity adsorbents for lysozyme adsorption

Different adsorbents have been reported in the literature for protein purification. The authors have developed a novel and new approach to obtain high protein adsorption capacity utilizing a 2-methacrylamidoalanine-containing membrane. Amino acid ligand 2-methacrylamidoalanine (MAAL) monomer was synthesized using methacryloyl chloride and alanine. Poly(2-hydroxyethylmethacrylate-co-2-methacrylamidoalanine) [p(HEMA-co-MAAL)] membranes were then prepared by UV-initiated photopolymerization of HEMA and MAAL in the presence of an initiator (azobisisobutyronitrile, AIBN). The synthesized MAAL monomer was characterized by NMR. p(HEMA-co-MAAL) membranes were characterized by swelling studies, porosimeter, SEM, FTIR, and elemental analysis. These membranes have macropores in the size range of 5-10 microm. Cu(II) ions (25.9 mmol/m2) were chelated on these membranes. p(HEMA-co-MAAL) membranes were used to study the adsorption of lysozyme from aqueous media containing different amounts of lysozyme (0.1-3.0 mg/l) and at different pH values (4.0-8.0). The non-specific adsorption of lysozyme on the pHEMA membranes was negligible (0.9 microg/cm2). Incorporation of MAAL increased the lysozyme adsorption significantly up to 2.96 mg/cm2. The lysozyme adsorption capacity of the Cu(II) incorporated membranes (9.98 mg/cm2) was greater than that of the p(HEMA-co-MAAL) membranes. More than 90% of the adsorbed lysozyme was desorbed in 1 h in the desorption medium containing 1.0 M NaCl and 0.025 M EDTA. The metal-chelate affinity membranes are suitable for repeated use for more than ten cycles without a noticeable loss of capacity.     

Binding affinity of surface functionalized gold nanoparticles to hydroxyapatite

Gold nanoparticles (Au NPs) have been investigated for a number of biomedical applications, including drug and gene delivery vehicles, thermal ablation therapy, diagnostic sensors, and imaging contrast agents. Surface functionalization with molecular groups exhibiting calcium affinity can enable targeted delivery of Au NPs to calcified tissue, including damaged bone tissue. Therefore, the objective of this study was to investigate the binding affinity of functionalized Au NPs for targeted delivery to bone mineral, using hydroxyapatite (HA) crystals as a synthetic analog in vitro. Au NPs were synthesized to a mean particle size of 10-15 nm and surface functionalized with either L-glutamic acid, 2-aminoethylphosphonic acid, or alendronate, which exhibit a primary amine for binding gold opposite carboxylate, phosphonate, or bisphosphonate groups, respectively, for targeting calcium. Bisphosphonate functionalized Au NPs exhibited the most rapid binding kinetics and greatest binding affinity to HA, followed by glutamic acid and phosphonic acid. All functional groups reached complete binding after 24 h. Equilibrium binding constants in de-ionized water, determined by nonlinear regression of Langmuir isotherms, were 3.40, 0.69, and 0.25 mg/L for bisphosphonate, carboxylate, and phosphonate functionalized Au NPs, respectively. Functionalized Au NPs exhibited lower overall binding in fetal bovine serum compared to de-ionized water, but relative differences between functional groups were similar.     

PEG对肝素化PCL/PEG人工血管膜材料中肝素释放的影响

目的 研究聚乙二醇(PEG)的加入对肝素化聚己内酯/聚乙二醇(PCL/PEG)人工血管膜材料中肝素体外释放的影响.方法 通过共混法和冷冻干燥技术制备不同PEG质量分数(0、5％、10％、15％)的肝素化PCL/PEG膜材料,并通过体外释放实验考察PEG的加入对肝素释放性能的影响.同时,通过X射线衍射、傅里叶红外光谱和差示扫描热分析仪探究PEG的加入对基体结构性能的影响.结果 PEG的加入降低了肝素从基体释放的难度,提高了肝素第1天的平均释放速率和34 d内的累积释放率,且两者在一定程度上随着PEG质量分数的增加而增大.X射线衍射、傅里叶红外光谱和差示扫描热分析结果均表明,肝素的加入会使PCL膜的结晶度在一定程度上有所增大,但整体影响并不显著,且肝素的加入会促进PEG晶粒的生长,肝素和PEG在基体中呈现共域化分布.结论 利用共混法和冷冻干燥技术制备了肝素化PCL/PEG膜材料,并可通过调控PEG的质量分数在一定程度上实现对肝素释放行为的控制,进而预测试样在一定程度上具有抗凝作用,该材料有望用作小口径人工血管膜材料.     

Cellular responses to electrospun membranes made from blends of PLLGA with PEG and PLLGA-b-PEG

Control of cellular responses is crucial for the use of electrospun membranes in biomedical applications, including tissue engineering or biomedical devices. However, it is still unclear whether adhesion and proliferation of fibroblasts is stimulated or inhibited on polyethylene glycol (PEG)-modified electrospun membranes. In this study, poly(L-lactide-co-glycolide) (PLLGA)-PEG copolymer and pure PEG were blended with PLLGA, and then electrospun onto nonwoven membranes. The effects of blending of PLLGA-PEG or pure PEG on the adsorption of proteins, and further on the adhesion and proliferation of L929 fibroblasts on the electrospun membranes were investigated. Addition of PLLGA-PEG or PEG significantly improved the hydrophilicity of the electrospun membranes. Pure PEG had no obvious effects on the growth of L929 fibroblasts; in contrast, PLLGA-PEG significantly inhibited the adsorption of proteins and the proliferations of the cells on the electrospun membranes. In response to diminished protein adsorption, mRNA expression of genes related to cell adhesion and migration was up-regulated. The limited effects of pure PEG were probably caused by its preferential dissolution, whereas membrane-confined PLLGA-PEG displayed excellent performance on the inhibition of protein adsorption and cell proliferation. ? 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:2897-2904, 2012.     

PEG adsorption of autoantibodies causes loss of concomitant alloantibody

Use of polyethylene glycol (PEG) to promote adsorption of autoantibodies is reported to give good recovery of concomitant alloantibodies. In initial experiments, PEG and ZZAP (Ficin and DTT) adsorption procedures were compared for removal of autoantibody and recovery of alloantibody. Postadsorption studies (n = 11) were performed and hemagglutination scores compared. In subsequent studies, equal volumes of alloantibody containing sera, PEG, and antigen-negative red blood cells (RBCs) were used in twofold adsorption experiments. Saline was substituted for PEG for control purposes. Postadsorption titers and immunoglobulin levels were determined. Autoantibodies were completely removed by both methods (n = 5); better by PEG (n = 3); better by ZZAP (n = 1); and not adsorbed (n = 1), and partially adsorbed by both (n = 1). Alloantibody recovery was comparable in three cases (E, K, Jka) but weaker by at least one reaction grade in four (K,E, Jka, and antibody to low-frequency antigen). The latter anti-Jka reacted 1+ with Jk(a+b+) RBCs after ZZAP adsorption but was nonreactive with the same RBCs following PEG adsorption. Titers of six alloantibodies adsorbed with antigen-negative RBCs in PEG were markedly weaker (range 2 to 8) compared to saline controls (range 4 to 32). IgG levels for PEG adsorbed (range 128 to 243 mg/dL) were 50% lower than controls (range 265 to 505 mg/dL). Although PEG adsorption is effective in removing autoantibody, the precipitation of immunoglobulin by PEG may result in failure to detect underlying alloantibody.     

Crystal structure and mesophase morphology of MBPE polyethers containing odd-number methylene spacers

A series of polyethers was synthesized from 4-[2-(4-hydroxyphenyl)ethyl]-3-methylphenol and α, ω-dibromoalkenes, MBPE-n. The polymers with odd-numbered methylene spacers show a monotropic mesophase behavior during cooling from the isotropic melt before crystallization. The crystal structures of MBPE (n = odd) polyethers have been investigated through wide angle X-ray diffraction fiber patterns. Two crystallographic periods along the c-axis are found, one of which corresponds to the length of methylene spacers, and the other is close to an integral number times the length of the repeating unit. Polarized light microscopy observations of the uniaxially oriented samples obtained through mechanical shear show a banded texture, which is a typical morphology found in liquid crystal polymers. Transmission electron microscopy experiments provide morphological evidence to identify that this mesophase is a nematic liquid crystal state based on the disclination defect patterns defined by Frank. A relationship between splay elastic constant k₁₁ and bend elastic constant k₃₃ is discussed through lamellar decoration of disclination defects.     

The use of polyethylene glycol (PEG) to enhance the adsorption of autoantibodies

The use of polyethylene glycol (PEG) to enhance the adsorption of warm autoantibodies on red blood cells (RBCs) was evaluated in our laboratory in an effort to reduce the time and cost associated with routine differential adsorptions. Sera from 19 patients with warm autoantibodies were tested. Fourteen of these sera contained alloantibodies or additional autoantibody specificities underlying the dominant autoantibody. The sera were differentially adsorbed using equal volumes of serum, reagent RBCs, and PEG for 15 minutes at 37 degrees C. The PEG/serum mixture was harvested and used for testing. Six drops of the PEG/serum mixture were tested against reagent RBCs for 15 minutes at 37 degrees C. An antiglobulin test was then performed using anti-IgG. The PEG adsorption technique took a total of 10 hours to completely eliminate autoantibody reactivity in all 19 samples. The reference method required a total of 59.5 hours to adsorb the autoantibodies in all 19 samples. Two weak alloantibody specificities (anti-K, anti-Jkb), known to be present in the serum, were not detected in the PEG tests. Four specificities were weaker with the PEG adsorbed serum. All other alloantibody specificities (13) were detected with equal or greater strength in the PEG adsorbed serum. The use of PEG to enhance the adsorption of autoantibodies should be considered as an option to reduce the time and cost of labor-intensive differential adsorptions. Laboratories should be cautioned that weak alloantibodies may not be detected using this method.     

Fibrinogen adsorption and platelet interactions on polymer membranes

The hemocompatibility of four different wettable polymer membranes, namely Cuprophan (CE), polyether-polycarbonate (PC-PE), polysulfone (PSU), and polyetherimide (PEI), was investigated with respect to flbrinogen (Fng) adsorption and platelet adhesion/activation. In order to estimate the polar and dispersion components of the surface free energy, contact angles using water/vapor and water/n-hexadecane systems were measured. Adsorption of flbrinogen was studied using fluorescence-labeled protein. The adsorption isotherms showed that the amount and the affinity of adsorbed Fng increased with decreasing surface wettability of the membranes, which correlates with the dispersion and polar components of the surface free energy. The conformational changes of adsorbed Fng were detected by measuring the difference between monoclonal antibody binding to the conformation-sensitive epitope in the D-domain and the binding of polyclonal anti-Fng antibody. The anticipated conformational/orientational changes were greater for PEI and PSU membranes (the least wettable membranes) and negligible for the more wettable PC-PE and CE membranes. In addition, a possible relationship with the degree of platelet activation was found, showing negligible platelet adhesion on PC-PE and CE, but high platelet adhesion on PEI and PSU. Furthermore, platelets were spread to a large extent on PEI, while the formation of aggregates was observed on PSU. This may correspond to the anticipated differences in the conformational state of Fng on both membranes.     

Fibrinogen adsorption and platelet interactions on polymer membranes

The hemocompatibility of four different wettable polymer membranes, namely Cuprophan (CE), polyether-polycarbonate (PC-PE), polysulfone (PSU), and polyetherimide (PEI), was investigated with respect to fibrinogen (Fng) adsorption and platelet adhesion/activation. In order to estimate the polar and dispersion components of the surface free energy, contact angles using water/vapor and water/n-hexadecane systems were measured. Adsorption of fibrinogen was studied using fluorescence-labeled protein. The adsorption isotherms showed that the amount and the affinity of adsorbed Fng increased with decreasing surface wettability of the membranes, which correlates with the dispersion and polar components of the surface free energy. The conformational changes of adsorbed Fng were detected by measuring the difference between monoclonal antibody binding to the conformation-sensitive epitope in the D-domain and the binding of polyclonal anti-Fng antibody. The anticipated conformational/orientational changes were greater for PEI and PSU membranes (the least wettable membranes) and negligible for the more wettable PC-PE and CE membranes. In addition, a possible relationship with the degree of platelet activation was found, showing negligible platelet adhesion on PC-PE and CE, but high platelet adhesion on PEI and PSU. Furthermore, platelets were spread to a large extent on PEI, while the formation of aggregates was observed on PSU. This may correspond to the anticipated differences in the conformational state of Fng on both membranes.     

Synthesis,characterization and properties of liquid crystalline bismaleimides containing phenylbenzoate mesogens and polymethylenic spacers

This paper describes the synthesis and characterization of four bismaleimides containing a phenylbenzoate mesogenic group and differing by the length of the polymethylenic spacers. They were prepared by reacting 4‐maleimidobenzoyl chloride with diphenols containing methylene bridges. The cured resins are stable up to 380°C in air. Smectic liquid crystalline behavior was observed in those materials. Two of them could be crosslinked in either smectic or isotropic phase. We have also found that the degree of cure can affect the formation of a liquid crystalline phase. Isothermal cure of initially isotropic material can form a material that exhibits a liquid crystalline phase.     

Effect of flexible spacers in liquid crystalline copolyesters containing a non-linear biphenol moiety

A series of copolyesters 2 containing both linear mesogenic and non-linear non-mesogenic aromatic ester units was prepared and characterized for the ability of the latter to either modify or destabilize the liquid-crystalline (LC) properties of the former. The mesogenic units were formed from the reaction of 1,4-phenylene diacetate ( 3 ) with 4,4′-decamethylenedioxydibenzoic acid ( 5 ), whereas the non-mesogenic units were formed from reaction of the latter monomer with the diacetate of the non-linear biphenol, sulfonylbis(1,4′-phenylene) diacetate ( 4 ). The presence of the flexible spacer in each unit allows the copolyesters to form a nematic phase even at a content of non-mesogenic units as high as approximately 80 mole-%. Copolyester compositions with mesogenic unit contents approaching this limit for LC behavior appear to form melts which contain both nematic and isotropic phases below the isotropization transitions.     

Heparin functionalized PEG gels that modulate protein adsorption for hMSC adhesion and differentiation

Heparin was modified with methacrylate groups, copolymerized with dimethacrylated poly(ethylene glycol), and analyzed as a localized delivery vehicle for bFGF and synthetic extracellular matrix for the differentiation of hMSCs. By deriving cues from molecules normally present in the extracellular matrix (ECM), a complex network of collagens, laminin, fibronectin, glycosaminoglycans, and growth factors, synthetic cell scaffolds can be designed that actively sequester important bioactive signals. Among the glycosaminoglycans, heparin binds reversibly with many proteins, therefore, poly(ethylene glycol) based biomaterials, normally resistant to cell adhesion, functionalized with heparin in order to sequester important proteins, can actively and selectively stimulate desired cell functions. Results demonstrate that methacrylate-modified heparin retained its ability to bind heparin-binding proteins both in solution and when copolymerized with dimethacrylated PEG in a hydrogel. In addition, the heparin functionalized gels can deliver biologically active bFGF for up to 5 weeks. Finally, the gels were examined as a potential scaffold for hMSC culture and were found to promote adhesion, proliferation, and osteogenic differentiation.     

Binding of bovine factor VIII-coated colloidal gold particles to receptors on platelet membranes

Bovine factor VIII/platelet aggregating factor was adsorbed onto gold granules and the protein-gold complex added to either formalin-fixed or fresh washed human platelets. Following aggregation, binding of gold granules to the platelets was measured by monitoring the optical density of colloidal gold remaining in the supernatant. Scatchard analysis of binding data indicated that multiple classes of binding sites were present. The number of high affinity binding sites per formalin-fixed platelet dependend on the concentration of ristocetin: 420 gold granules were calculated to bind at 1.4 mg/ml of ristocetin, 610 at 0.6 mg/ml of ristocetin and 875 when no ristocetin was added. Fresh washed platelets bound 1350 granules per cell in the absence of ristocetin. We conclude that during platelet aggregation, induced by bovine factor VIII, the binding sites on the platelet surface are only partially occupied.     

Equilibrium and kinetic adsorption of bacteria on alluvial sand and surface thermodynamic interpretation

Equilibrium and kinetic adsorption of Escherichia coli HB 101, E. coli JM 109, Pseudomonas fluorescens, Pseudomonas putida and Pseudomonas sp. on alluvial sand from the Canadian River alluvium (Norman, OK) was investigated through column experiments. Equilibrium adsorption of these five bacterial strains followed the Freundlich expression and was a function of zero energy points, an indication of the zero energy buffer zone. Among the microorganisms studied, P. putida had the greatest equilibrium adsorption (162.4 x 10(8) cell/g sediment with a microbial injectate concentration of 10(8) cell/ml), followed by Pseudomonas sp. (127.9 x 10(8) cell/g sediment), E. coli HB 101 (62.8 x 10(8) cell/g sediment), E. coli JM 109 (58.4 x 10(8) cell/g sediment), and P. fluorescens (42.6 x 10(8) cell/g sediment). The first-order kinetic adsorption rate coefficient was an exponential function of the total interaction free energy between the bacteria and sediment evaluated at the primary minimum, Delta G(132)(TOT) (PM). E. coli HB 101 had the greatest kinetic adsorption rate coefficient on the sediment (5.10 h(-1)), followed by E. coli JM 109 (4.52 h(-1)), P. fluorescens (2.12 h(-1)), P. putida (2.04 h(-1)), and Pseudomonas sp. (1.34 h(-1)).     

Evaluation of microparticle leakage during DALI LDL adsorption in a simulated clinical setting

The aim of the present study was to investigate microparticle (Mp) leakage during simulated LDL-hemoperfusion using 12 DALI 750 adsorbers and the original DALI hardware under conditions strictly comparable to the clinical situation. Thus, the sessions were divided into 4 sections, i.e. priming and preparation of the adsorber followed by treatment (6-7 L at a flow rate of 60 ml/min) and reinfusion. As Mp counts can be performed only in clear, cell-free media, blood was replaced by normal saline in sections 2-4 of the simulated sessions. Mp counts were analysed for > or = 2, > or = 5, > or = 10 and > or = 25 microm particle sizes in the efferent line post adsorber using a standard light blockage method. As there are no official thresholds for particle release in extracorporeal circuits, the limits for infusion of large fluid volumes of 500, 100 (80), 25 and 5 (3) Mp/ml according to the Europ?ische Arzneimittelbuch, the British and American Pharmacopoeias were used. Mean particle counts for the sections 3 and 4 in which the patient is connected to the efferent line were 19, 7, 2 and 0 Mp/ml and amounted to < 10% of the above mentioned limits. Modifications of the standard simulation procedure by inserting additional pump stops or using different flow rates during the treatment phase slightly increased Mp leakage, but never exceeded the prescribed limits. In summary, no undue particle release could be detected during simulations of the clinical DALI LDL-adsorption procedure.     

Serum protein adsorption and platelet adhesion on aspartic-acid-immobilized polysulfone membranes

Polysulfone (PSf) membranes that covalently conjugated with aspartic acid (ASP-PSf) were prepared and analyzed for hemocompatability. Compared to PSf or other types of surface-modified PSf membranes, the ASP-PSf membranes had a reduced ability to adsorb protein from either a plasma solution or a mixed solution of albumin, globulin and fibrinogen. This appears to be due to the creation of a hydrophilic surface by the aspartic acid zwitterion immobilized on the ASP-PSf membranes. Furthermore, the analyses of membrane protein adsorption showed that a mixed protein solution recapitulates the cooperative adsorption of proteins that occurs in plasma. We also found that the number of adhering platelets was the lowest on the ASP-PSf membranes and, in general, that platelet adhesion decreased in parallel with fibrinogen adsorption. In summary, aspartic acid immobilized on the ASP-PSf membranes, which have zwitterions with a net zero charge, effectively contributes to the hydrophilic and hemocompatible sites on the surface of the hydrophobic PSf membranes.     

Serum protein adsorption and platelet adhesion on pluronic-adsorbed polysulfone membranes

We examined plasma protein adsorption and platelet adhesion to polysulfone (PSf) flat membranes coated with Pluronic with varying polyethylene oxide (PEO) block length. Adsorption of albumin, globulin and fibrinogen to Pluronic-coated PSf membranes was independent of plasma dilution when concentrations of human blood plasma above 20% were applied. Increasing coating concentrations of aqueous Pluronic solution resulted in decreased protein adsorption by the PSf membranes. Pluronic F68, which was more hydrophilic than Pluronic L62 or L64 and had 80% of PEO content, was the most effective at suppressing the adsorption of plasma proteins and platelet adhesion to PSf membranes. We developed a mixed protein solution containing human albumin, gamma-globulin and fibrinogen to attempt to mimic the competitive and cooperative binding effects found in plasma. Fibrinogen adsorption from plasma could be recapitulated by the mixed protein solution. The number of platelets adhering to the PSf membranes decreased as the coating concentration of Pluronic solution was increased, and platelet adhesion decreased in parallel with fibrinogen adsorption. These results suggest that the bioinert property of PEO segments in the Pluronic, which is ascribed to their high flexibility in aqueous media, suppresses the adsorption of plasma proteins and platelets to the Pluronic-coated PSf membranes.     

Protein adsorption and separation on amphoteric chitosan/carboxymethylcellulose membranes

This article reported the preparation of an amphoteric natural polymeric membrane-macroporous chitosan (CS)/carboxymethylcellulose (CMC) blend membrane and the utilization of such a membrane on the membrane chromatography for bioseparation. The membranes were prepared by solution blending of CS and CMC solution, and using silica particles as porogen. Both glutaraldehyde and epichlorohydrin were used as crosslinking agent to increase its chemical stability in aqueous solution. Such a natural polymeric membrane can be served as an amphoteric membrane because of the amino group on CS and the carboxymethyl group on CMC, in which the surface charge can be changed with the environmental pH. Ovalbumin (pI = 4.6) and lysozyme (pI = 11) were selected as model proteins. These two proteins adsorption on different CS/CMC blend membranes with different initial protein concentrations at different pH values were investigated in batch systems. The results indicated that the maximum adsorption for lysozyme and ovalbumin was at pH 9.2 and 4.8 respectively, and the adsorption capacity on the membrane both increased with the increase of initial protein concentration. Though the adsorption mechanism of lysozyme and ovalbumin was found not the same, the maximum adsorption capacity of two proteins on the membranes was quite similar (about 250 mg/g). Moreover, the desorption ratio of both proteins was found to be more than 90% that implied CS/CMC blend membrane could separate proteins by adsorption-desorption process. Finally, both lysozyme and ovalbumin were successfully separated from their binary mixture only by adjusting the pH of the feed and the desorption solution.     

Serum protein adsorption and platelet adhesion on aspartic-acid-immobilized polysulfone membranes

Polysulfone (PSf) membranes that covalently conjugated with aspartic acid (ASP-PSf) were prepared and analyzed for hemocompatability. Compared to PSf or other types of surface-modified PSf membranes, the ASP-PSf membranes had a reduced ability to adsorb protein from either a plasma solution or a mixed solution of albumin, globulin and fibrinogen. This appears to be due to the creation of a hydrophilic surface by the aspartic acid zwitterion immobilized on the ASP-PSf membranes. Furthermore, the analyses of membrane protein adsorption showed that a mixed protein solution recapitulates the cooperative adsorption of proteins that occurs in plasma. We also found that the number of adhering platelets was the lowest on the ASP-PSf membranes and, in general, that platelet adhesion decreased in parallel with fibrinogen adsorption. In summary, aspartic acid immobilized on the ASP-PSf membranes, which have zwitterions with a net zero charge, effectively contributes to the hydrophilic and hemocompatible sites on the surface of the hydrophobic PSf membranes.