血浆蛋白在聚苯乙烯—g—（二八烷聚氧乙烯）表面吸…

利用放射碘同位素标记技术研究了三种主要血浆蛋白质（白蛋白、免疫球蛋白或纤维蛋白原）在聚苯乙烯－ｇ－（十八烷聚氧乙烯）接枝共聚物表面的吸附动力学、等温吸附及竞争吸附。表面蛋白质吸附量和表面的ＳＰＥＯ含量非单调关系，与ＳＰＥＯ侧链的疏水末端基效应密切相关。二元蛋白质竞争吸附结果表明这三种蛋白质的相对竞争吸附能力为纤维蛋白原最大，免疫球蛋白次之，白蛋白最小。     

血浆蛋白质在聚苯乙烯-g-(十八烷聚氧乙烯)表面吸附的研究

利用放射碘同位素标记技术研究了三种主要血浆蛋白质（白蛋白、免疫球蛋白或纤维蛋白原）在聚苯乙烯－ｇ－（十八烷聚氧乙烯）接枝共聚物表面的吸附动力学、等温吸附及竞争吸附。表面蛋白质吸附量和表面ＳＰＥＯ含量非单调关系，与ＳＰＥＯ侧链的疏水末端基效应密切相关。二元蛋白质竞争吸附结果表明这三种蛋白质的相对竞争吸附能力为纤维蛋白原最大，免疫球蛋白次之，白蛋白最小。     

用椭圆偏振术研究血清白蛋白和纤维蛋白原在硅片及聚氨酯薄膜表面的吸附行为

用椭圆偏振术研究了牛血清白蛋白（ＢＳＡ）和人纤维蛋白原（ＦＧＮ）在亲水硅片表面上的吸附行为。结果表明：蛋白质浓度大于５μｇ／ｍｌ时，相同蛋白质浓度下，ＢＳＡ的最终吸附量小于ＦＧＮ。在蛋白质浓度变化的情况下，ＢＳＡ在吸附液蛋白质浓度约为１０μｇ／ｍｌ时即达到饱和吸附（即最终吸附量不再随蛋白浓度提高而增加），而ＦＧＮ达到饱和吸附时的吸附液浓度约为２０μｇ／ｍｌ，ＢＳＡ和ＦＧＮ吸附液浓度同时３０μｇ／ｍ     

血浆蛋白分子在单壁碳纳米管无纺膜表面吸附行为的研究

近年来,碳纳米管的独特表面拓扑结构、化学组成和优异的物理性能已经吸引了众多领域的研究兴趣,以生物医学应用为目标的探索性研究正在迅速形成一个新的方向。我们以血液接触环境下的应用为目标,通过扫描电镜观察、表面元素分析、以及利用酶联免疫分析技术,系统研究了与凝血过程密切相关的纤维蛋白原、白蛋白、免疫球蛋白以及新鲜血浆在单壁碳纳米管无纺膜(SWNT膜)表面的吸附行为。实验结果显示,单壁碳纳米管无纺膜对血浆中的纤维蛋白原分子具有强烈的倾向性吸附,对免疫球蛋白也显示出一定的吸附性,但是,对白蛋白分子却几乎不吸附。血浆蛋白分子在SWNT膜表面的吸附行为与其在其它碳材料表面和其它大多数生物材料表面的吸附行为显著不同。SWNT膜对血浆蛋白分子的独特吸附作用有可能对后续的血液细胞响应产生重要影响。     

聚醚型聚氨酯材料表面纤维蛋白原的吸附性研究

本文采用放射性同位素标记的方法研究了嵌段聚醚型聚氨酯在纯纤维蛋白原溶液中和稀释血浆中的表面纤维蛋白原吸附性规律，考察了聚醚型聚氨酯的特性粘数及溶液体系中的ＮａＣｌ浓度对材料表面纤维蛋白原吸附性的影响，结果表明，随着聚合物特性粘数的增大，材料表面的纤维蛋白原吸附量呈降低的趋势；溶液体系中盐浓度的降低导致纤维蛋白原凝固性增强，在纯纤维蛋白原溶液中，材料表面纤维蛋白原的吸附量相应增多，而在稀释血浆中，纤维蛋白原的吸附量相应减少，在达到最低值后又有上升的趋向，表明纤维蛋白原在材料表面的吸附还受血浆中其它大分子的影响。     

纤维蛋白原活性测定在血液流变性中的意义

目的研究血浆中纤维蛋白原活性对血液流变性的影响。方法对３７９例患者进行血浆和血清粘度的测定,应用其结果计算出纤维蛋白原的活性,按照公式;纤维蛋白原活性（ｇ／Ｌ）＝纤维蛋白原量（ｇ／Ｌ）／［血浆粘度（ｍＰａ·ｓ）一血清粘度（ｍＰａ·ｓ）］。结果在纤维蛋白原活性增强时,血浆粘度有所提高,并使全血粘度升高。此纤维蛋白原活性与其含量的增粘作用不成比例。结论临床测定纤维蛋白原活性能提高血液流变学检测的特异性及敏感性。     

用SPR生物传感器研究纤维蛋白原在生物医用材料表面的吸附

材料表面对血浆蛋白的吸附特性 ,是研究和评价生物医用材料血液相容性的重要依据。本文用自制的表面等离激元 (SPR)传感器 ,测量了金膜、磷脂DSPC膜、成都科大Ⅱ型聚氨酯、Pellethane2 36 3 55D聚氨酯及有机玻璃膜表面对纤维蛋白原的动态吸附特性 ,在纤维蛋白原溶液浓度为5mg/ml的相同条件下 ,磷脂DSPC膜表面吸附纤维蛋白原的速度最低 ,饱和吸附浓度也最小 (表面浓度为 1ng/mm2 )。其次是裸金膜 (表面浓度为 3.5ng/mm2 ) ,再其次是成都科大Ⅱ型聚氨酯膜 (表面浓度为 3.8ng/mm2 )和Pellethane 2 36 3 55D聚氨酯 (表面浓度为 4 .3ng/mm2 ) ,吸附速度和吸附量最高的是有机玻璃膜 (表面浓度为 4 .5ng/mm2 )。结果表明 ,材料表面对纤维蛋白原的吸附动力学特性 ,与材料的血液相容性密切相关。表面等离激元技术与本文采用的在金膜上铺展高分子材料的离心铺膜法和LB技术等样品制备技术相结合 ,为生物材料表面对蛋白质吸附特性的实时、动态、原位研究提供了一种新的高灵敏度的方法 ,并可能发展成为一种材料生物相容性的测试和评价的新方法。     

纤维蛋白原活性测定在血液流变学检测中的作用及意义

目的：研究血浆中纤维蛋白原活性对血液流变性的影响。方法：对临床３７９例患者进行血浆和血清粘度的测定,应用其结果计算出纤维蛋白原的活性,按照公式：纤维蛋白原活性（ｇ／Ｌ）＝纤维蛋白原量（ｇ／Ｌ）／［血浆粘度（ｍＰａ·ｓ）－血清粘度（ｍＰａ·ｓ）］。结果：结果显示,只有在纤维蛋白原活性增强时,血浆粘度才有所提高,从而使全血粘度升高,故此纤维蛋白原活性与其含量的增粘作用不成比例。结论：临床测定纤维蛋白原活性能提高血液流变学检查的特异性及敏感性。     

用SPR生物传感器研究纤维蛋白原在生物医用材料表面？…

材料表面对血浆蛋白的吸附特性，是研究和评价生物医用材料血液相容性的重要依据。本文用自制的表面等离激元（ＳＰＲ）传感器，测量了金膜、磷脂ＤＳＰＣ膜、成都科大Ⅱ型聚氨酯、Ｐｅｌｌｅｔｈａｎｅ２３６３－５５Ｄ）聚氨酯及有机玻璃膜表面对纤维蛋白原的动态吸附特性，在纤维蛋白原溶液浓度为５ｍｇ／ｍｌ的相同条件下，磷脂ＤＳＰＣ膜表面吸附纤维蛋白原的速度最低，饱和吸附浓度也最小（表面浓度为１ｎｇ／ｍｍ＾２）。其次     

测定FG—血小板结合亲合力变化的新方法

本研究以单克隆抗体Ｍ１（４Ａ５）为工具，酶联免疫测试技术（ＥＬＩＳＡ）为途径，研究吸附在生物材料表面的纤维蛋白原（ＦＧ）的三个可能位点，与粘附的血小板相结合的结合亲合力（ａｆｉｎｉｔｙ）变化。通过测定一系列不同浓度的Ｍ１（４Ａ５）单克隆抗体同ＦＧ的结合数量变化，利用相应数学模型，可计算出结合亲合常数Ｋａ，从而为深入认识材料表面的血液相容性质，提供了一种定量尺度。该方法比过去仅利用ＦＧ与单一浓度抗体反应，测其被吸附的数量，并用以作为血液相容性的一个定量指标的方法，更为灵敏、准确。     

The Vroman effect in tube geometry: the influence of flow on protein adsorption measurements.

The transient adsorption of fibrinogen from plasma (a manifestation of the Vroman effect), due in large part to displacement by trace proteins such as high-molecular-weight kininogen (HK), factor XII, and plasminogen, has traditionally been studied in nonflowing systems in this laboratory. This paper reports new data on adsorption in tubing geometry under laminar flow. Fibrinogen adsorption from human blood plasma and whole blood diluted to varying exents was measured on glass and polyethylene tubing. The presence of flow did not change the nature of the Vroman effect, except that the processes of adsorption and displacement, which are typically diffusion-limited in static systems, were augmented by convective transport. At the highest applied shear rates of 408 and 510 s-1, the initial adsorption rate of fibrinogen was estimated to be 5.0 X 10(-5) cm/s on both surfaces. The intrinsic rate of displacement of fibrinogen (due to the Vroman effect) at high shear rates was about ten times faster from glass than from polyethylene based on data taken 5 min after the experiment started. The rates of fibrinogen adsorption and displacement were not observed to be significantly augmented by the cellular elements of whole blood at dilutions exceeding 20:1. The consistently observed axial dependence of adsorption in static and flow experiments in tubing geometry was investigated. It was concluded that the effect results, under most conditions, from the creation of a concentration boundary layer during the displacement of the equilibrating buffer by the injected protein solution. The possibility of local depletion due to rapid adsorption during injection or the final displacement of the protein solution was concluded to make lesser contributions to axial variations in measured adsorption.     

Polyethylene oxide surfaces of variable chain density by chemisorption of PEO-thiol on gold: adsorption of proteins from plasma studied by radiolabelling and immunoblotting

The mechanisms involved in the inhibition of protein adsorption by polyethylene oxide (PEO) are not completely understood, but it is believed that PEO chain length, chain density and chain conformation all play a role. In this work, surfaces formed by chemisorption of PEO-thiol to gold were investigated: the effects of PEO chain density, chain length (600, 750, 2000 and 5000 MW) and end-group (-OH, -OCH3) on protein adsorption from plasma are reported. Similar to previous single protein adsorption studies (L.D. Unsworth et al., Langmuir 2005;21:1036-41) it was found that, of the different surfaces investigated, PEO layers formed from solutions near the cloud point adsorbed the lowest amount of fibrinogen from plasma. Layers of hydroxyl-terminated PEO of MW 600 formed under these low solubility conditions showed almost complete suppression (versus controls) of the Vroman effect, with 20+/-1 ng/cm2 adsorbed fibrinogen at the Vroman peak and 6.7+/-0.6 ng/cm2 at higher plasma concentration. By comparison, Vroman peak adsorption was 70+/-20 and 50+/-3 ng/cm2, respectively, for 750-OCH3 and 2000-OCH3 layers formed under low solubility conditions; adsorption on these surfaces at higher plasma concentration was 16+/-9 and 12+/-3 ng/cm2. Thus in addition to the effect of solution conditions noted previously, the results of this study also suggest a chain end group effect which inhibits fibrinogen adsorption to, and/or facilitates displacement from, hydroxyl terminated PEO layers. Fibrinogen adsorption from plasma was not significantly different for surfaces prepared with PEO of molecular weight 750 and 2000 when the chain density was the same ( approximately 0.5 chains/nm2) supporting the conclusion that chain density may be the key property for suppression of protein adsorption. The proteins eluted from the surfaces after contact with plasma were investigated by SDS-PAGE and immunoblotting. A number of proteins were detected on the various surfaces including fibrinogen, albumin, C3 and apolipoprotein A-I. The blot responses were zero or weak for all four proteins of the contact system; some complement activation was observed on all of the surfaces studied.     

Festschrift in honor of the 65th birthday of Dr John L. Brash. Part 2

Adsorption of fibrinogen from buffer as a single protein and from plasma to four materials has been studied. The two NIH-NHLBI primary reference standards, filler free polydimethylsiloxane and low density polyethylene, were used along with polyvinylchloride and cellulose materials supplied by the IUPAC Working Party. The materials were examined in both film and tubing form, except for polydimethylsiloxane which was studied only in tubing form. Adsorption was measured at room temperature using ¹²⁵I-Iabelled fibrinogen. The order of adsorbed amounts in the single protein experiments was found to be: cellulose < PVC < PE = PDMS. Apparent adsorption affinities are in the same order. In plasma, all surfaces except cellulose showed maxima in adsorption as a function of plasma concentration after 5 min contact. This is indicative of initial adsorption followed by displacement of fibrinogen (the Vroman effect). Cellulose showed very low adsorption of fibrinogen from plasma. The Vroman maxima were more pronounced on the tubing samples than on the films, and, as for the single protein experiments, adsorption was found to be less on tubing than on film samples. A tentative interpretation of the Vroman effect data suggests that the order of procoagulant activity of the materials may be: PDMS = PE < PVC < cellulose.     

Detection of surface-adsorbed (lipo)proteins by means of a two-step enzyme-immunoassay: a study on the Vroman effect

In view of reports on the involvement of high-molecular-weight (HMW) kininogen and high-density lipoprotein (HDL) in the Vroman effect, we studied the adsorption of fibrinogen, HMW kininogen, HDL and several other proteins from pooled human plasma and congenitally HMW kininogen-deficient plasma onto glass and low-density polyethylene, both as a function of the plasma concentration and the contact time. Mixtures of purified (lipo)proteins were also included in the study. Protein adsorption was determined by means of a two-step enzyme-immunoassay. Our results support the hypothesis that HMW kininogen is involved in the displacement of fibrinogen, which is almost instantly adsorbed from normal plasma onto glass. On hydrophobic polymers like polyethylene, the low amounts of adsorbed fibrinogen and HMW kininogen from plasma and concentrated plasma solutions may be due to a preferential adsorption of HDL.     

Changes in fibrinogen adsorbed to segmented polyurethanes and hydroxyethylmethacrylate-ethylmethacrylate copolymers.

Fibrinogen adsorption from blood to biomaterials may regulate platelet adhesion and thrombus formation because of fibrinogen's central role in the coagulation cascade and its ability to bind specifically to the platelet membrane glycoprotein (GP) IIb-IIIa. Adsorption of fibrinogen from blood plasma to many materials exhibits a maximum with respect to plasma dilution and exposure time (the Vroman effect). In this study fibrinogen adsorption to several polymers was examined to ascertain the influence of controlled changes in surface chemistry on the Vroman effect. The materials included hydroxyethylmethacrylate-ethylmethacrylate (HEMA/EMA) copolymers, Biomer, and a series of segmented polyurethanes (PEUs), two of which contained fluorinated chain extenders. Each material exhibited maximal adsorption of fibrinogen at intermediate plasma concentrations. Little effect of soft-segment type or molecular weight was observed and no significant differences in fibrinogen adsorption to the fluorinated PEUs were seen. Changes in the strength of fibrinogen attachment to these materials with time after adsorption were also assessed. Fibrinogen adsorbed for 1 min was displaced more readily by blood plasma than that adsorbed for 1 h, regardless of the material. The more hydrophobic polymers exhibited greater retention of adsorbed fibrinogen. In addition, the fraction of fibrinogen retained by polyethylene depended on the amount of fibrinogen adsorbed to the surface, being greatest when the surface loading was the least. These studies indicate that spreading or transition of adsorbed fibrinogen molecules from a weakly to tightly bound state is a general consequence of protein adsorption to solid surfaces.     

Adsorption behavior of fibrinogen to sulfonated polyethyleneoxide-grafted polyurethane surfaces

Fibrinogen adsorptions to surface modified polyurethanes (PU, PU-PEO, and PU-PEO-SO₃) were studied from plasma in vitro. PU and PU-PEO surfaces demonstrated that initial adsorption increases with increasing plasma concentration in kinetic profiles and adsorption time in adsorption profiles as a function of plasma concentration, but after the plateau is reached, its adsorption amount decreases as plasma concentration (0.2-2.0%) and adsorption time (1-120 min) increase, respectively. In contrast, PU-PEO-SO₃ showed that initial adsorption is almost same regardless of plasma concentration and adsorption time, which is due to the high affinity of surface sulfonate group to fibrinogen. All the surfaces indicated the Vroman effect at about 0.6% plasma concentration; however, the displacement was relatively low. Adsorbed amount of fibrinogen at steady state decreased in the order: PU > PU-PEO-SO₃ > PU-PEO, regardless of adsorption time and plasma concentration. The adsorption behavior of PU-PEO-SO₃ is attributed to both effect of low binding affinity of PEO chain and high affinity of pendant sulfonate group toward fibrinogen.     

Adsorption of plasminogen from plasma to lysine-derivatized Polyurethane surfaces

The adsorption of plasminogen, the principal protein of the fibrinolytic pathway in blood, to a number of solid surfaces from plasma was investigated. This study forms part of a larger project to develop a fibrinolytic surface for blood-contacting applications. Polyurethanes incorporating lysine residues were developed in an attempt to promote selective adsorption of plasminogen from plasma through lysine-binding sites in the plasminogen molecule. The adsorption of plasminogen to these surfaces as well as to glass, ‘conventional’ polyurethanes and precursor sulphonated polyurethanes was investigated. Adsorption from citrated human plasma diluted with isotonic Tris buffer (pH 7.4) was measured under static conditions at room temperature using radioiodinated plasminogen. The following trends were observed. (1) Adsorption increases monotonically with increasing plasma concentration and there is no suggestion of transient adsorption (Vroman effect) on any of the surfaces studied. (2) Sulphonate groups appear to have a strong effect on plasminogen adsorption as was found previously for adsorption from buffer. (3) The lysine-derivatized material having the highest lysine content may show a slight increase in plasminogen binding affinity compared to its sulphonated precursor.     

Interactions of proteins in human plasma with modified polystyrene resins

Investigations are reported on the composition of protein layers adsorbed from plasma to various modified polystyrene resins. As well as polystyrene itself, polystyrene bearing sulfonate groups in the benzene rings, and polystyrene sulfonate in which the sulfonate groups were converted to amino acid sulfamide, were investigated. Some of these resins were shown in previous work to have anticoagulant properties. To study the adsorption of proteins from plasma, the resins were exposed to citrate anticoagulated human plasma for 3 h. Adsorbed proteins were then eluted sequentially by 1M Tris buffer and 4% SDS solution, and examined by SDS-PAGE. The gel patterns were similar on all resins except polystyrene. From the MWs of the gel bands, the major protein component appeared to be fibrinogen. Smaller amounts of plasminogen, transferrin, albumin, and IgG were also present. In addition, Ouchterlony immunoassay of the eluates from one resin gave positive identification of complement C3, fibronectin, IgG, and IgM. Many other minor gel bands remain unidentified. A consistent finding for all resins was the presence of plasmin-type fibrinogen degradation products though the amounts varied with resin type. It is concluded from this (and from experiments showing FDP formation when fibrinogen was absorbed to the resins, from buffer containing a trace of plasminogen) that the functional groups in these materials promote the adsorption of plasminogen and its activation to a plasmin-like molecule. It appears from the substantial quantities of fibrinogen adsorbed to these materials after 3 h exposure to plasma that the Vroman effect (giving transient adsorption of fibrinogen) is not operative on these materials. It is hypothesized that specific interactions occur between fibrinogen and sulfonate groups.     

The effects of temperature and buffer on fibrinogen adsorption from blood plasma to glass

[125I]-Fibrinogen was used to measure the adsorption of fibrinogen from baboon plasma to two types of glass (Pyrex and a borosilicate glass) at 25 and 37 degrees C using two different buffers to dilute the plasma, the first being citrate-phosphate buffered saline (CPBSz) and the second isotonic Tris-saline (TRIS), both pH 7.4. In addition, the effects of hydration conditions, rinsing techniques, and glass-cleaning treatments on fibrinogen adsorption were evaluated. The data reveal that lower temperatures and the use of TRIS to dilute the plasma significantly enhance fibrinogen adsorption to both types of glass. As has been observed in the past, fibrinogen adsorption peaked at intermediate plasma concentrations on both Pyrex and borosilicate glass (the so-called Vroman effect), but almost twice as much fibrinogen adsorbed to glass when TRIS was used to dilute the plasma instead of CPBSz. Moreover, up to five times as much fibrinogen adsorbed to both types of glass at 25 degrees C compared with 37 degrees C. No effects of the rinsing technique or glass-cleaning treatment were observed.     

Analysis of proteins adsorbed to glass from human plasma using immunoblotting methods

Glass beads were contacted with heparinized human plasma and the adsorbed proteins eluted sequentially with 1 M tris buffer, pH 7.4, and 2% SDS. The proteins in the eluates were analyzed by SDS-polyacrylamide gel electrophoresis and immunoblotting procedures using antisera to 16 common plasma proteins. All sixteen proteins were found to be present in the eluates. The immunoblots provided evidence of contact phase activation although the role of the surface could not be ascertained since some contact activation was apparent in the starting plasma. Evidence was also obtained for the occurrence of complement activation and the fibrinogen Vroman effect on the glass bead surface. Extensive degradation of high molecular weight proteins observed previously in eluates from clinically used hemodialyzers [3] was not observed in the present in vitro plasma experiments, thus supporting the hypothesis that such degradation is due to enzymes liberated in the in vivo experiments by blood cell damage.