Protein-resistant and fibrinolytic polyurethane surfaces

Surfaces with resistance to non-specific protein adsorption and a high capacity to bind plasminogen from plasma are developed for application as fibrinolytic surfaces in blood contact. A new method is reported for grafting poly(OEGMA-co-HEMA) copolymers on polyurethane surfaces. The OEGMA provides effective protein resistance due to the PEG side chains and the HEMA provides a high density of OH groups for attachment of lysine. Adsorption of fibrinogen from buffer and plasma to these surfaces is low, indicating significant protein resistance. Plasminogen binding from plasma is high, and clot dissolution on surfaces where plasminogen adsorbed from plasma is converted to plasmin is rapid.     

聚(N-异丙基丙烯酰胺)改性硅表面与血浆蛋白质的相互作用

通过表面引发原子转移自由基聚合(ATRP)在硅表面接枝了聚(N-异丙基丙烯酰胺)(PNIPAAm)聚合物刷,并考察了PNIPAAm改性表面在单一蛋白质溶液以及血浆中与血浆蛋白质之间的相互作用.蛋白质吸附测试表明,与未改性的硅表面相比,改性后的表面对纤维蛋白原的吸附量大大降低,特别是在血浆中纤维蛋白原吸附量小于5ng/c...     

Bioinert surface to protein adsorption with higher generation of dendrimer SAMs

Interactions between proteins and biomaterial surfaces correlate with many important phenomena in biological systems. Such interactions have been used to develop various artificial biomaterials and applications, in which regulation of non-specific protein adsorption has been achieved with bioinert properties. In this research, we investigated the protein adsorption behavior of polymer brushes of dendrimer self-assembled monolayers (SAMs) with other generations. The surface adsorption properties of proteins with different pI values were examined on gold substrates modified with poly(amidoamine) dendrimer SAMs. The amount of fibrinogen adsorption was greater than that of lysozyme, potentially because of the surface electric charge. However, as the generations increased, protein adsorption decreased regardless of the surface charge, suggesting that protein adsorption was also affected by density of terminal group.     

Poly(N-vinylpyrrolidone)-modified surfaces repel plasma protein adsorption

The present work aimed to study the interaction between plasma proteins and PVP-modified surfaces under more complex protein conditions.In the competitive adsorption of fibrinogen(Fg) and human serum albumin(HSA),the modified surfaces showed preferential adsorption of HSA.In 100%plasma,the amount of Fg adsorbed onto PVP-modified surfaces was as low as 10 ng/cm~2,suggesting the excellent protein resistance properties of the modified surfaces.In addition, immunoblots of proteins eluted from the modified surfaces after plasma contact confirmed that PVP-modified surfaces can repel most plasma proteins,especially proteins that play important roles in the process of blood coagulation.     

能够促进细胞黏附的生物活性表面的制备

报道了一种能够促进细胞黏附的生物活性表面的制备方法.首先通过表面引发原子转移自由基聚合方法在硅表面接枝了聚(N-甲基丙烯酰氧基琥珀酰亚胺)(PNMASI)聚合物刷.随着反应时间的增加,接枝层厚度基本呈线性增长,表明聚合反应具有一定的可控性.蛋白质吸附测试表明PNMASI改性后的表面具有高密度固定生物分子的能力.同时,通...     

Specific and non-specific interactions of procaine with activated carbon surfaces

The adsorption of procaine on eight activated carbon surfaces from simulated intestinal fluid (SIF) was evaluated using a rotating bottle method and isoperibol calorimetry. The adsorption data were fit using the modified Langmuir-like equation to calculate the non-specific and specific adsorption capacities. The surface atomic compositions were determined by X-ray photoelectron spectroscopy (XPS). A linear relationship was found between the relative non-specific adsorption capacity and the unoxidized hydrocarbon content of the activated carbon surfaces, which indicated that the non-specific adsorption site for procaine is the bare carbon surface. The apparent area occupied per procaine molecule, calculated from the specific capacity, was linearly correlated to the sum of the relative percentages of the C-O and O-C=O functional states on the surfaces. This suggested that the primary adsorption sites for procaine on the activated carbon surfaces were the oxygen-containing functional states of C-O and O-C=O, where procaine was adsorbed via hydrogen bonding. The differential heats of displacement for procaine on the four activated carbon surfaces are approximately equal to each other, which indicated that the interactions between procaine and the functional states on all surfaces are energetically equivalent.     

Hemocompatible polyurethane surfaces

With the aim of improving the hemocompatibility of blood‐contacting devices, antithrombotic or fibrinolytic biological molecules‐containing polyurethane (PU) materials have been developed. Cationic PU surfaces were prepared by grafting poly(dimethylaminoethyl methacrylate) and quaternizing the tertiary amino groups with iodomethane. The surfaces were characterized by water contact angles and X‐ray photoelectron spectroscopy. The materials (PU‐CH₃I) were treated with antithrombotic or fibrinolytic drugs, such as hirudin or tissue plasminogen activator (tPA) in Tris‐buffered saline (pH 9.0) to yield hirudin‐loaded or tPA‐loaded PU surfaces. The hirudin and tPA quantity of the surfaces was observed using a radiolabeling method. The quantities of hirudin and tPA taken up by the cationic surfaces were significantly greater than those on the unmodified PU: approximately 200‐fold greater for hirudin and 10‐fold for tPA. The release of the bound hirudin and tPA from the materials in contact with plasma was slow, and at 48 h, ~78% of the initial hirudin and ~26% of the initial tPA remained bound. The activity of the bound hirudin and tPA, as measured by a plasma recalcification assay, was largely preserved. This approach may have potential for the development of surfaces having antithrombotic or fibrinolytic properties. Copyright © 2011 John Wiley & Sons, Ltd.     

蛋白A连续床亲和毛细管色谱柱的制备及性能考察

人免疫球蛋白 G(HIg G)是一种重要的生物大分子 ,是人血浆中的主要成分之一 ,通常采用免疫学的方法测定 .蛋白 A(Protein A)与免疫球蛋白 (HIg G)的 Fc区之间具有很强的特异性亲和作用 ,因而固载蛋白 A的亲和介质可用于免疫球蛋白及单克隆抗体的分离、纯化和分析测定[1～ 3 ] .根据固定相存在形式的不同 ,毛细管色谱柱主要有开管、填充和连续床柱 3种方式 .连续床具有相比高、易制备 (一步合成 )、孔径易控制、不需烧塞子和易改性等优点 .连续床与其它常用的亲和介质 (如球型凝胶颗粒、灌流色谱基质 [4、 5] 、膜介质 [6,7] 等 )相比具…     

Regenerable electrochemical immunological sensing at DNA nanostructure-decorated gold surfaces

A regenerable electrochemical immunosensor with novel 3D DNA nanostructure-decorated gold surfaces was developed by taking advantage of DNA-directed antibody conjugation and high resistance to non-specific protein adsorption.     

Development of a fibrinolytic surface: specific and non-specific binding of plasminogen

Plasminogen is the primary zymogen in the fibrinolytic pathway, and its primary function involves degradation of fibrin. Biomaterials often show adsorption of fibrinogen and subsequent formation of fibrin. Plasminogen's function in vivo could be adapted to facilitate its activation and fibrinolytic function on a biomaterial surface. In order to elucidate plasminogen function adsorbed to a model fibrinolytic surface ligands known to affect plasminogen properties in solution were attached to model silica surfaces to study the effects of immobilized ligands as fibrinolytic activators. Model silica surfaces were synthesized which contained covalently attached lysine moieties (surface I), sulfonate moieties (surface II) or a combination of both (surface III). Lysine moieties on these model surfaces interact specifically with multiple lysine-binding sites of plasminogen and induce a number of changes in conformation and function. Sulfonate moieties interact non-specifically with accessible lysine and arginine residues of plasminogen and also affect the function of plasminogen. Inherent physico-chemical properties monitored following plasminogen adsorption were activation to plasmin, enzymatic activity, fluorescent intensity, and fluorescent polarization, monitored by total internal reflection fluorescence, each of which are affected by plasminogen conformation.

Correlations were as follows: increased fluorescent intensity and decreased fluorescent polarization were indicative of plasminogen conformational changes and are correlated to increased enzymatic activity of plasmin. Surfaces I and III showed a 20% increase in fluorescent intensity, and a 25% and 8% decrease in fluorescent polarization, respectively, in comparison to surface II. The specific activity for surfaces I and III was increased 11.3 and 1.8 fold above that found for surface II. Plasminogen incubated with sulfonate groups in solution resulted in no increase in fluorescent intensity and a slight decrease in fluorescent polarization as compared with plasminogen alone and reduced specific activity of plasmin in the presence of sulfonate as compared with plasmin alone. Lysine or ε-aminocaproic acid (ACA) incubated with plasmin in solution showed a 30% and 10% increase in fluorescent intensity, a 24% and 5% decrease in fluorescent intensity, and maximum specific activity increased 3.6 and 2.5 fold, respectively, over plasminogen alone.

Interactions of plasminogen with ligands for its lysine-binding sites produced dramatic effects both in solution and adsorbed to model fibrinolytic surfaces. The characterization of these interactions along with known fibrin interactions will allow selection of appropriate surface modifications to enhance the fibrinolysis of thrombus formed at a biomaterial interface. These modifications may lead to a native-like surface structure to protein and cellular components of blood and create a more biocompatible surface.     

Phenobarbital interactions with derivatized activated carbon surfaces

The interactions between phenobarbital and activated carbon surfaces were studied in detail in this work. This was accomplished by utilizing different reagents to manipulate the surface polar functional group compositions of different activated carbons, and determining how those modifications changed phenobarbital adsorption. Oxidation of an activated carbon surface caused a systematic decrease in the basal carbon surface, resulting in a concurrent systematic decrease in the non-specific adsorption of phenobarbital. Even more interesting, it was shown for the first time that chemical reduction of some of the carbonyl-containing functional groups on the activated carbon surface caused a significant increase in the specific adsorption of phenobarbital without any significant effect on the non-specific adsorption. These results support the notion that the OH groups on activated carbon surfaces are the specific adsorption sites for phenobarbital from aqueous solutions, and that the basal carbon surface is the region where non-specific adsorption takes place.     

Colloid probe AFM investigation of interactions between fibrinogen and PEG-like plasma polymer surfaces

Interaction forces between surfaces designed to be protein resistant and fibrinogen (Fg) were investigated in phosphate-buffered saline with colloid probe atomic force microscopy. The surfaces of the silica probes were coated with a layer of fibrinogen molecules by adsorption from the buffer. The technique of low-power, pulsed AC plasma polymerization was used to make poly(ethylene glycol) (PEG)-like coatings on poly(ethylene teraphthalate) by using diethylene glycol vinyl ether as the monomer gas. The degree of PEG-like nature of the films was controlled by use of a different effective plasma power in the chamber for each coating, ranging from 0.6 to 3.6 W. This produced a series of thin films with a different number of ether carbons, as assessed by X-ray photoelectron spectroscopy. The interaction force measurements are discussed in relation to trends observed in the reduction of fibrinogen adsorption, as determined quantitatively by (125)I radio-labeling. The plasma polymer coatings with the greatest protein-repelling properties were the most PEG-like in nature and showed the strongest repulsion in interaction force measurements with the fibrinogen-coated probe. Once forced into contact, all the surfaces showed increased adhesion with the protein layer on the probe, and the strength and extension length of adhesion was dependent on both the applied load and the plasma polymer surface chemistry. When the medium was changed from buffer to water, the adhesion after contact was eliminated and only appeared at much higher loads. This indicates that the structure of the fibrinogen molecules on the probe is changed from an extended conformation in buffer to a flat conformation in water, with the former state allowing for stronger interaction with the polymer chains on the surface. These experiments underline the utility of aqueous surface force measurements toward understanding protein-surface interactions, and developing nonfouling surfaces that confer a steric barrier against protein adsorption.     

Use of cellulose derivatives on gold surfaces for reduced nonspecific adsorption of immunoglobulin G

This study addresses the design of protein-repellent gold surfaces using hydroxyethyl- and ethyl(hydroxyethyl) cellulose (HEC and EHEC) and hydrophobically modified analogues of these polymers (HM-HEC and HM-EHEC). Adsorption behavior of the protein immunoglobulin G (IgG) onto pure gold and gold surfaces coated with cellulose polymers was investigated and described by quartz crystal microbalance with dissipation monitoring (QCM-D), atomic force microscopy (AFM) and contact angle measurements (CAM). Surfaces coated with the hydrophobically modified cellulose derivatives were found to significantly outperform a reference poly(ethylene glycol) (PEG) coating, which in turn prevented 90% of non-specific protein adsorption as compared to adsorption onto pure gold. HEC and EHEC prevented around 30% and 60% of the IgG adsorption observed on pure gold, while HM-HEC and HM-EHEC were both found to completely hinder biofouling when deposited on the gold substrates. Adsorption behavior of IgG has been discussed in terms of polymer surface coverage and roughness of the applied surfaces, together with hydrophobic interactions between protein and gold, and also polymer-protein interactions.     

Self-assembly of poly(ethylene glycol)-based block copolymers for biomedical applications

Nanostructure fabrication from block copolymers is discussed in this review paper. Particularly, novel approaches for the construction of functionalized poly(ethylene glycol) (PEG) layers on surfaces were focused to attain the specific adsorption of a target protein through PEG-conjugated ligands with a minimal non-specific adsorption of other proteins. Furthermore, surface organization of block copolymer micelles with cross-linking cores was described from the standpoint of preparation of a new functional surface-coating with a unique macromolecular architecture. The micelle-attached surface and the thin hydrogel layer made by layered micelles exhibited non-fouling properties and worked as a reservoir for hydrophobic reagents. These PEG-functionalized surface in brush form or in micelle form can be used in diverse fields of medicine and biology to construct high-performance medical devices including scaffolds for tissue engineering and matrices for drug delivery systems.     

Chitosan-N-poly(ethylene oxide) brush polymers for reduced nonspecific protein adsorption

The possibility of using a novel comb polymer consisting of a chitosan backbone with grafted 44 units long poly(ethylene oxide) side chains for reducing nonspecific protein adsorption to gold surfaces functionalized by COOH-terminated thiols has been explored. The comb polymer was attached to the surface in three different ways: by solution adsorption, covalent coupling, and microcontact printing. The protein repellent properties were tested by monitoring the adsorption of bovine serum albumin and fibrinogen employing surface plasmon resonance and imaging null ellipsometry. It was found that a significant reduction in protein adsorption is achieved as the comb polymer layer is sufficiently dense. For solution adsorption this was achieved by adsorption from high pH solutions. On the other hand, the best performance of the microcontact printed surfaces was obtained when the stamp was inked either at low or at high pH. For a given comb polymer layer thickness/poly(ethylene oxide) density, significant differences in protein repellent properties were observed between the different preparation methods, and it is suggested that a reduction in the mobility of the comb polymer layer generated by covalent attachment favors a reduced protein adsorption.     

Multiscale modeling and simulations of protein adsorption: progresses and perspectives

Protein adsorption, which shows wide prospects in many practical applications such as biosensors, biofuel cells, and biomaterials, has long been identified as a very complex problem in interface science. Here, we present a review on the multiscale modeling and simulation methods of protein adsorption on surfaces with different properties. First, various simulation algorithms (replica exchange, metadynamics, TIGER2A, and PSOVina) and protein models (colloidal, coarse-grained, and all-atom models) are introduced. Then, recent molecular simulation progresses about protein adsorption on different material surfaces (such as charged, hydrophobic, hydrophilic, and responsive surfaces) are retrospected. It has been demonstrated that the adsorption orientation of proteins on charged surfaces and hydrophobic surfaces can be controlled by the electrical dipole and the hydrophobic dipole of proteins, respectively. Superhydrophilic zwitterionic surfaces can resist protein adsorption because of the strong hydration. Under the stimuli of external conditions, the surface properties of materials can be modulated, and thus, the adsorption/desorption of proteins on responsive surfaces can be controlled. Finally, the future directions of molecular simulation study of protein adsorption are discussed.     

聚苯乙烯-g-聚氧乙烯接枝共聚物表面阻抗蛋白质吸附的研究

利用放射性碘标记技术研究了血浆蛋白质-缓冲溶液体系在聚苯乙烯-g-聚氧乙烯接枝共聚物表面的等温吸附和吸附动力学。材料表面蛋白质等温吸附量或平衡吸附量随表面PEO含量增加而下降;吸附量最低值小于0.25μg,cm^-2;同时探讨了材料表面”梳状“结构对材料表面PEO侧链阻抗蛋白质性能的影响。     

Studies of electroosmotic flow and the effects of protein adsorption in plasma‐polymerized microchannel surfaces

This paper presents a study of EOF properties of plasma‐polymerized microchannel surfaces and the effects of protein (fibrinogen and lysozyme) adsorption on the EOF behavior of the surface‐modified microchannels. Three plasma polymer surfaces, i.e. tetraglyme, acrylic acid and allylamine, are tested. Results indicate EOF suppression in all plasma‐coated channels compared with the uncoated glass microchannel surfaces. The EOF behaviors of the modified microchannels after exposure to protein solutions are also investigated and show that even low levels of protein adsorption can significantly influence EOF behavior, and in some cases, result in the reversal of flow. The results also highlight that EOF measurement can be used as a method for detecting the presence of proteins within microchannels at low surface coverage (<1 ng/cm² on glass). Critically, the results illustrate that the non‐fouling tetraglyme plasma polymer is able to sustain EOF. Comparison of the plasma‐polymerized surfaces with conventionally grafted polyelectrolyte surfaces demonstrates the stabilities of the plasma polymer films, enabling multiple EOF runs over 3 days without deterioration in performance. The results of this study clearly demonstrate that plasma polymers enable the surface chemistry of microfluidic devices to be tailored for specific applications. Critically, the deposition of the non‐fouling tetraglyme coating enables stable EOF to be induced in the presence of protein.     

Protein adsorption on to low-temperature isotropic carbon 4. Competitive adsorption on carbon and silica studied by two-dimensional electrophoresis

Two-dimensional polyacrylamide gel electrophoresis (2D PAGE) was applied to the study of competitive protein adsorption from diluted human plasma. We obtained the depletion (adsorption) of some 25 plasma proteins in the presence of low-temperature isotropic carbon (LTIC) or silica powders. The depletion data are used as a measure of protein adsorptivity. Generally, proteins of lowest abundance have the highest tendency to associate with the two solid surfaces studied. The adsorptivity of a protein is largely determined by its solubility. Most proteins detected exhibit similar depletion behavior on both adsorbents, suggesting a multilayer adsorption process. Three proteins, hemopexin, apolipoprotein A I, and apolipoprotein A II, are depleted differently in the presence of LTIC and silica powders.     

蛋白A高效亲和膜色谱法测定人血浆中免疫球蛋白G的含量

 研究了蛋白Ａ高效亲和膜色谱对水溶液及人血浆中人免疫球蛋白Ｇ（ＨＩｇＧ）的特异性吸附和定量测定。方法具有较高的精确度和较好的重复性：ＨＩｇＧ标样５次重复进样的相对标准偏差为１．５％，人血浆样品３次重复进样的相对标准偏差为３．６％；所测得的定量标定曲线的线性相关系数达到０．９９９３；不含己二胺间隔臂的亲和介质的非特异性吸附极低，基本检测不出来。快速实验中，一次分析可在０．５ｍｉｎ内完成。实验表明，利用所建立的方法对人血浆中的ＨＩｇＧ进行定量测定可以得到较为满意的结果。