含1,2,3-三氮唑官能团嵌段共聚物的制备及其蛋白质的吸附

通过"点击化学"反应合成了含1,2,3-三氮唑官能团的单体(VBTM),再采用可逆加成-断裂链转移(RAFT)活性自由基聚合法,制备了含有1,2,3-三氮唑官能团的聚苯乙烯(PS-b-PVBTM)两嵌段共聚物。将PS-b-PVBTM旋涂于金片表面成膜,形成以聚苯乙烯链段为核、PVBTM链段为冠的胶束结构;此薄膜于90℃退火24 h后,球状结构转变为表面富集PS的环状结构。采用表面等离子体谐振仪(SPR)原位检测蛋白质在PS-b-PVBTM上的吸附动力学。结果表明,当缓冲液为中性时,聚合物薄膜对牛血清蛋白(BSA)和肌红蛋白(Myoglobin)没有吸附,而对等电点为11的溶菌酶(Lysozyme)则有吸附;经退火处理后的聚合物薄膜对Lysozyme的吸附量减少了0.26 ng/mm2;当缓冲液为酸性时,该聚合物薄膜对BSA产生吸附,且吸附量随缓冲液pH值的降低而增加。PS-b-PVBTM对以上3种蛋白质的吸附为静电吸附。     

聚丙烯酰吡咯作为蛋白质吸附材料的研究

近些年, 具有电活性的聚合物在生物分子吸附材料方面的应用越来越广. 而导电聚合物的前聚体化合物的合成(如带吡咯基团的聚合物)对于生物分子的吸附研究非常重要. 详细研究了牛血清白蛋白(BSA)在导电聚合物前聚体—聚丙烯酰吡咯(PAP)表面上的吸附规律. 首先, 采用自由基聚合方法合成PAP, 通过spin-coating方法将PAP涂覆到50 nm厚的金膜上, 制备出均匀聚合物薄膜. 然后, 采用傅立叶转换红外光谱(FT-IR)和X射线光电子能谱(XPS)对PAP的化学结构及元素构成进行了分析, 同时考察了PAP膜在不同pH值的生物缓冲液环境中的水接触角. 在详细研究了聚合物膜的化学结构和表面性质之后, 采用表面等离子体谐振仪(SPR)原位监测BSA在PAP上的吸附动力学过程, 发现其吸附行为主要受缓冲液的pH值和BSA浓度的影响. 在不同生物缓冲液环境下, 蛋白质和聚合物膜之间的各种作用力会发生变化, 最终导致蛋白质吸附行为以及吸附量的不同, 这为以后制备更加敏感的导电蛋白质芯片奠定了基础.     

Desorption Potentials of Alkyl Alcohols and Specific Adsorption of Anions

Abstract

The potentials of desorption of various alkyl alcohols have been studied as a function of concentration of alcohol and of the nature and concentration of various electrolytes. Specific adsorption of the electrolyte ions is reflected in shifts of the desorption peaks of the alcohols. At anodic potentials, the order of specific adsorption appears to be chloride > sulfate >perchlorate > fluoride, and at cathodic potentials (vs. S. C. E.), chloride > perchlorate > sulfate > fluoride.     

微多相聚氨酯大孔树脂吸附细胞色素c的研究

微多相聚氨酯大孔树脂吸附细胞色素ｃ的研究史林启＊何炳林（南开大学吸附分离功能高分子材料国家重点实验室、高分子化学研究所天津３０００７１）关键词微多相聚氨脂大孔树脂，细胞色素ｃ，吸附选择性１９９６－０７－１５收稿，１９９６－１０－２４修回国家自然科学基...     

壳聚糖共混微球的制备及吸附性能测试

壳聚糖（CS）分子中含有游离态的氨基和羟基,是一种高效的离子吸附剂,而且氨基可质子化形成阳离子,使得壳聚糖对阴离子及两性化合物都具有较强的吸附能力.壳聚糖引入羧甲基后水溶性和反应活性大大增强.实验中以乳化-化学交联法制备壳聚糖/羧甲基壳聚糖（CMC）四种共混微球,通过对比,发现当CS与CMC的质量比为4∶1、2∶3时,成球硬度好,形状明显,大小均匀.随着CMC含量的增加,所成微球对牛血清白蛋白（BSA）的吸附能力逐渐增强.因此,当CS与CMC质量比为2∶3时共混微球自身的物理形态与吸附性能均达到良好状态,是共混高效离子吸附剂的最佳比例选择.     

Quantitative Assessment of Protein Adsorption by Combination of the Enzyme-Linked Immunosorbent Assay with Radioisotope-Based Studies

Protein adsorption at polymer surfaces has been investigated by means of both ELISA and radiolabeling techniques. Most of the data obtained are linearly related to each other for protein concentrations between 0.01 and 1 μg/ml, i.e., the concentration range in which the maximum amount of adsorbed active protein (ELISA) is achieved. The correlation of ELISA data with radioisotope-based measurements allows quantification of the former. Specific correlation factors are described. Adsorption is shown to be strongly dependent on the polymer/protein system.     

聚丙烯酸酯改性水性聚氨酯的制备

在回顾聚丙烯酸酯改性水性聚氨酯的研究历史基础上，系统地介绍了聚丙烯酸酯改性水性聚氨酯乳液（PUA）的制备方法，其中包括聚氨酯（PU）和聚丙烯酯（PA）的直接掺混法、PU和PA的乳液共聚法，接枝法，互穿网络法，核壳聚合法，对这些方法做了简单的评述，对其应用范围及前景进行了初步探讨。     

Study of Protein Adsorption/Adhesion Behaviors on Solid Beads Surface with Different Surface Properties

Three kinds of chitosan (CS) derivatives have been prepared via polyethyleneimine (PEI) or polyethylene glycol (PEG) together with PEI modified chitosan. FTIR, x-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA)/differential thermal analysis (DTA) proved the successful linkage, and XPS and zeta potential analysis show that these derivatives beads possess different surface nature. The PEI modified chitosan derivative is made in acid solution (A-PEI-CS) and the one added with additional PEG (PEG–CS-PEI) has showed higher swelling degree than their counterpart derivative prepared at basic condition (B-PEI-CS). Although the nitrogen content of A-PEI-CS is higher than that of B-PEI-CS, due to the better surface hydrophilicity, the B-PEI-CS beads are more capable of adsorbing bovine serum albumin (BSA) protein. Electrostatic attraction facilitates protein adsorption in a narrow acidic pH range while hydrophilicity hinders protein adhering to the beads’ surface at any pH.     

Protein Adsorption on Derivatives of Hyaluronan

Summary: Serum protein adsorption and fibroblast cell adhesion on photo reactive hyaluronic acid (Hyal-N₃) and its sulfated derivative (HyalS-N₃₎ was analysed using a combination of quartz crystal microbalance (QCM) and cell adhesion assays. There was no significant differences in the amount of protein adsorbed onto the two polymers, however proteins were found to be more loosely bound to HyalS-N₃ compared with Hyal-N₃. Approximately 17% and 31% of the fibronectin interacting with Hyal-N₃ and HyalS-N₃ respectively was found to be irreversibly bound after rinsing with MilliQ water, SDS and urea. Proteins were exposed to the polymers before cell adhesion was monitored for a period of 2 hours in serum free conditions. Minimal cell adhesion was observed on albumin-coated materials as well as serum precoated Hyal-N₃. Precoating the materials with fibronectin enhanced cell adhesion, although HyalS-N₃ experienced higher levels of cell adhesion than Hyal-N₃ and similar results were found for the serum precoated materials.     

Adsorption of Phenylalanine from Casein Hydrolysates

The specific diet therapy for phenylalaninemies requires special hydrolysates of proteins where phenylalanine content is reduced to approx 0.53% of the amino acids present. In previous work, Amberlite XAD-4 resin was used to retain phenylalanine from an acid hydrolysate of casein. It was also observed that the adsorption isotherm of phenylalanine on the resin showed a convex pattern that allowed a frontal chromatography. In the present study, this technique was improved, aiming at the processing of larger hydrolysates volumes. This was achieved with the use of two sequential columns (50 × 1 cm), each containing 34 cm³ of the resin, and joined through a 1-cm long tygon, tube 1 mm diameter. This system was used to process 100 mL of casein acid hydrolysate containing 12 g of free amino acid and allowed the reduction of phenylalanine content from 4.39 to 0.14% of the total amino acids present, within 1 h. It was also observed that this technique could not be directly applied to enzymatic hydrolysates of casein unless they were especially produced for this purpose, which means that in this kind of hydrolysate, phenylalanine should be free or linked in small adsorptive peptides.     

阴离子特性吸附和Pt(111)电极表面结构对乙二醇解离吸附动力学的影响

运用电化学循环伏安和程序电位阶跃方法研究了阴离子特性吸附和Pt(111)电极表面结构对乙二醇解离吸附反应动力学的影响. 结果表明, 阴离子特性吸附显著影响乙二醇的解离吸附, 在高氯酸介质中(无特性吸附)测得乙二醇解离吸附反应的初始速率vi以及解离吸附物种(DA)的饱和覆盖度均明显大于硫酸溶液(发生SO2-4/HSO-4特性吸附)中的相应值; 其平均速率v随电极电位的变化呈类似火山型分布, 最大值位于0.22 V(vs SCE)附近. 还发现通过不同处理获得的Pt(111)电极的不同表面结构对这一表面过程也具有显著的影响.     

Specific Features of the Adsorption of Carbon Monoxide on a Smooth Polycrystalline Platinum Electrode Modified with Adsorbed Silver Atoms

The adsorption of carbon monoxide at the surface of smooth polycrystalline platinum (smPt) is studied in conditions of a preliminary accumulation of various quantities of silver (θ_Ag) on the surface. A comparison with similar data obtained previously for Pt/Pt is conducted. It is discovered that on smPt, exactly as in the case of Pt/Pt, carbon monoxide undergoes adsorption at sites that are not occupied by adsorbed silver, without forcing the preliminarily adsorbed silver out. At small and intermediate Ag_ad, as opposed to Pt/Pt, a mere two peaks are observed in a voltametric curve in the region of electrodesorption of the mixed layer on smPt. It is shown that, in the region of potentials of the first peak, there occurs practically no transition of silver into solution in the course of oxidation of the mixed layer. Specific features that characterize the behavior of the CO_ads + Ag_ad mixed layer are discussed under the assumption about an “islet” character of the adsorption of silver.     

带正电荷蛋白在纳米/微米草酸钙晶体上的吸附特性及其与带负电荷蛋白吸附的比较

研究尺寸分别为100 nm和3 μm的一水草酸钙（COM）和二水草酸钙（COD）晶体对带正电荷的蛋白溶菌酶（LSZ）的吸附差异,并与带负电荷的蛋白牛血清白蛋白（BSA）的吸附进行了比较。LSZ在纳米/微米COM和COD晶体上的吸附都很好的拟合了Langmuir模型,属于单分子层吸附。纳米/微米COM和COD对LSZ的最大吸附量顺序为COD-100 nm >COM-100 nm >COD-3 μm >COM-3 μm;晶体的比表面积越大,曲率越小,晶体表面所带电荷越负,晶体结晶水越多,均导致LSZ吸附量越大。体系离子强度和pH值亦影响LSZ的吸附。随着NaCl浓度增加,LSZ的吸附量减小,说明Na⁺离子能与带正电荷的蛋白LSZ竞争晶体表面的吸附位点,导致晶体表面吸附LSZ的位点减少。晶体对LSZ的最大吸附量都出现在LSZ的等电点附近（pH=10.7）;在pH=5~8（生理条件）时,LSZ的吸附量随pH值的增大而增大。本文结果提示,通过减小尿液的pH值或者适当增大尿液的离子强度,可以减小LSZ在尿微晶上的吸附量,有可能达到抑制草酸钙结石的效果。     

In-vitro hemocompatibility evaluation of a thermoplastic polyurethane membrane with surface-immobilized water-soluble chitosan and heparin

The surface of a thermoplastic polyurethane (TPU) membrane was treated with low temperature plasma (LTP) and was then grafted with poly(acrylic acid) (PAA), followed by the grafting of water-soluble chitosan (WSC) and heparin (HEP). The surface was characterized with static contact-angle and X-ray photoelectron spectroscopy (XPS). The results showed that the surface densities of peroxides and PAA reached a maximum when treated with LTP for 90 s. A higher pH of the reacting solution led to higher graft densities of WSC and HEP. After WSC and HEP grafting, the hydrophilicity of the TPU membrane was increased. The adsorption of proteins on HEP-grafted TPU membranes was effectively curtailed. In addition, HEP grafting also reduced platelet adhesion, elevated thrombin inactivation, and prolonged the blood coagulation time. According to the L929 fibroblast cell growth inhibition index, the HEP-grafted TPU membranes exhibited non-cytotoxicity. Overall results demonstrated that the HEP immobilization could not only improve the hydrophilicity but also the hemocompatibility of the TPU membrane, while maintaining the ascendant biocompatibility.     

带正电荷蛋白在纳米/微米草酸钙晶体上的吸附特性及其与带负电荷蛋白吸附的比较

研究尺寸分别为100 nm和3μm的一水草酸钙(COM)和二水草酸钙(COD)晶体对带正电荷的蛋白溶菌酶(LSZ)的吸附差异,并与带负电荷的蛋白牛血清白蛋白(BSA)的吸附进行了比较。LSZ在纳米/微米COM和COD晶体上的吸附都很好的拟合了Langmuir模型,属于单分子层吸附。纳米/微米COM和COD对LSZ的最大吸附量顺序为COD-100 nmCOM-100 nmCOD-3μmCOM-3μm;晶体的比表面积越大,曲率越小,晶体表面所带电荷越负,晶体结晶水越多,均导致LSZ吸附量越大。体系离子强度和p H值亦影响LSZ的吸附。随着Na Cl浓度增加,LSZ的吸附量减小,说明Na+离子能与带正电荷的蛋白LSZ竞争晶体表面的吸附位点,导致晶体表面吸附LSZ的位点减少。晶体对LSZ的最大吸附量都出现在LSZ的等电点附近(p H=10.7);在p H=5~8(生理条件)时,LSZ的吸附量随p H值的增大而增大。本文结果提示,通过减小尿液的p H值或者适当增大尿液的离子强度,可以减小LSZ在尿微晶上的吸附量,有可能达到抑制草酸钙结石的效果。     

An Algorithm for Simulating Equilibrium Adsorption Characteristics of Branched Copolymer Chains at Solid‐Liquid Interface

An algorithm is developed for simulating adsorption of tree type block‐branched copolymer chains, of arbitrary architecture, from dilute solutions to solid surfaces. A continuum form of the self‐consistent field (SCF) theory is used. The chain architecture is first represented by a convergent tree‐graph, which is then converted into a special type of the connectivity matrix. This matrix is used for computing the configurational statistics of the chains in the adsorbed layer. The crucial step in the algorithm is to compute the junction (branch point) probability weights. A stepwise procedure for computing these probability weights is described. The capability of the algorithm has been demonstrated using illustrative examples.

     

Crystal Structures of 2-Aminobenzothiazole-based Inhibitors in Complexes with Urokinase-type Plasminogen Activator

Urokinase-type plasminogen activator （uPA） plays a crucial role in the regulation of plasminogen activation, tumor cell adhesion and migration. The inhibition of uPA activity is a promising mechanism for anti-cancer therapy. Most current uPA inhibitors employ a highly basic group （either amidine or guanidine group） to target the S1 pocket of uPA active site, which leads to poor oral bioavailability. Here we study the possibility of using less basic 2-aminobenzothiazole （ABT） as S1 pocket binding group. We report the crystal structures of uPA complexes with ABT or 2-amino-benzothiazole-6-carboxylic acid ethyl ester （ABTCE）. The inhibitory constants of these two inhibitors were measured by a chromogenic competitive assay, and it was found that ABTCE is a better inhibitor for uPA （Ki = 656 μM） than ABT （Ki = 5.03 mM）. This work shows that 2-amniobenzothiazole can be used as P1 group which may have better oral bioavailability than the commonly used amidine or guanidine group. We also found the ethyl ester group occupies the characteristic oxyanion hole and contacts to uPA 37- and 60-loops. Such work provides structural information for further improvements of potency and selectivity of this new class of uPA inhibitor.     

Adsorption of Mussel Protein on Polymer Antifouling Membranes: A Molecular Dynamics Study

Biofouling is one of the most difficult problems in the field of marine engineering. In this work, molecular dynamics simulation was used to study the adsorption process of mussel protein on the surface of two antifouling films—hydrophilic film and hydrophobic film—trying to reveal the mechanism of protein adsorption and the antifouling mechanism of materials at the molecular level. The simulated conclusion is helpful to design and find new antifouling coatings for the experiments in the future.     

PNIPAAm改性表面对蛋白质吸附的调控及其应用

根据不同领域的需要,控制蛋白质在材料表面的吸附是一个具有重要应用价值的课题。聚（N-异丙基丙烯酰胺）（PNIPAAm）改性表面能够响应外界温度变化从而改变其表面性质,这一特点为调控蛋白质的吸附提供了可能。近年来,研究者们应用多种表征方法考察了不同温度下蛋白质在PNIPAAm改性表面的吸附,并试图从分子水平上深入理解其吸附机制及影响因素。本文综述了近年来应用PNIPAAm改性表面对蛋白质吸附的研究及其最新进展。发现当PNIPAAm层厚度处于一定范围内时,PNIPAAm改性表面表现出对蛋白质吸附的温度敏感性,并可以利用这一性质将其应用于蛋白质纯化及分离和生物传感器等领域。而当PNIPAAm层厚度超过一个临界值时,PNIPAAm改性表面表现出良好的阻抗血浆蛋白质的性质,使其有望在血液相容性表面领域得到应用。最后,就PNIPAAm改性表面调控蛋白质吸附的未来发展方向简要地进行了展望。