Adsorption of bovine serum albumin at solid/aqueous interfaces

Adsorption of soluble serum proteins on hydrophilic and hydrophobic solid surfaces is important for biomaterials and chromatographic separations of proteins. The adsorption of bovine serum albumin (BSA) from aqueous solutions was studied with in situ ATR-IR spectroscopy, and with ex situ ATR-IR, ellipsometry, and water wettablity measurements. The results were used to quantitatively determine the adsorbed film thickness and surface density of BSA on hydrophilic silicon oxide/silicon surfaces, and on these surfaces covered with a hydrophobic lipid monolayer of dipalmitoylphosphatidylcholine (DPPC). The water contact angles were 5° for silicon oxide, 47° ± 1° for the DDPC monolayer, and 53° ± 1° for the BSA monolayers. At 25 °C, and with 0.01–1 wt% BSA in water, the surface densities range from Γ = 2.6–5.0 mg/m², and the film thicknesses range from d = 2.0–3.8 nm, on the assumption that the film is as dense as bulk protein. These results, and certain changes in the IR amide I and II bands of the protein, indicate that the protein adsorbs as a side-on monolayer, with some flattening due to unfolding or denaturation. The estimated -helical content for protein in buffer solutions is 15% higher than for solutions in water. The adsorption density reaches a steady-state value within 10 min for the lowest concentration, but does not appear to reach a steady-state value after 3 h f‘or the higher concentrations. Adsorption of BSA on a silicon oxide surface covered with a monolayer of DPPC leads to an adsorbed protein film of about half the thickness and surface density than on silicon oxide, but the same contact angle, indicating more protein unfolding on the hydrophobic than on the hydrophilic surface.     

Electrostatic interaction between chitosan-modified latex particles and bovine serum albumin

Electrostatic interaction between poly(methyl methacrylate) latex particles with different levels of chitosan modification and bovine serum albumin (BSA) was investigated. The critical flocculation concentration is in the range 5–15 nmol dm⁻³ for these latex products toward added BSA. A series of isothermal equilibrium adsorption experiments shows that the adsorption process is divided into two distinct intervals. Adsorption of BSA on latex particles in intervals I and II is primarily controlled by charge neutralization and hydrophobic interaction, respectively. Intervals I and II can be reasonably described by an empirical parabola equation and the Langmuir isotherm model, respectively. The maximum amount of BSA adsorbed per unit weight of polymer particles was observed at pH ≅ 5. A maximum elution yield of about 80% can be achieved using NaSCN as the elution electrolyte, and NaSCN is more effective in inducing desorption of BSA from the particle surface than NaCl. The chitosan content has very little effect on the interaction between latex particles and BSA. By contrast, the influence of the content of 2,2′-azobis(2-amidinopropane) dihydrochloride, a cationic initiator used in preparing the chitosan-modified latex products, on the BSA adsorption process is significant. Received: 26 March 1999 Accepted in revised form: 3 June 1999     

Evaluation of the adsorption affinity of proteins to calcium hydroxyapatites by desorption and pre-adsorption methods

The adsorption affinity of bovine serum albumin (BSA) and lysozyme (LSZ) to calcium hydroxyapatite (CaHAP) was evaluated by desorption and two step adsorption methods. These experiments were carried out at 15°C in a 1×10⁻⁴ mol dm⁻³ KCl solution of pH 6.0. BSA molecules were scarcely desorbed, exhibiting an irreversible adsorption of BSA, though LSZ slightly desorbed. This result supports our previous findings that LSZ adsorbs weakly onto phosphate ions exposed on ac or bc faces of CaHAP while BSA adsorbs strongly onto positively charged sites on ac or bc faces of CaHAP. The amount of adsorbed LSZ was markedly increased by the pre-adsorption of BSA, where LSZ was adsorbed onto BSA-covered CaHAP. On the other hand, the amount of adsorbed BSA was not changed by the pre-adsorption of LSZ. In both pre-adsorption systems it was confirmed by an HPLC method that no protein molecule pre-adsorbed was desorbed after the post-adsorption procedure. Therefore, it was interpreted that the enhancement of adsorption of positively charged LSZ is induced by an electrostatic attractive force through pre-adsorption of negatively charged BSA molecules with a high coverage. However, since the coverage of LSZ onto CaHAP is considerably low, no stimulation of BSA adsorption occurred on the LSZ-covered surface. The formation of double protein adsorbed layers consisting of pre- and post-adsorbed proteins was proposed.     

Adsorption of bovine serum albumin to acrylamide–itaconic acid hydrogels

In this study, acrylamide–itaconic acid hydrogels containing different amounts of itaconic acid prepared by irradiating with γ radiation are discussed. They have been used in experiments of swelling, diffusion and bovine serum albumin (BSA) adsorption. Maximum and minimum swellings were observed with water (1520%) and BSA (890%), respectively. Diffusion of water, NaCl and BSA within hydrogels were found to be non-Fickian in character. In the experiments of BSA adsorption, type III adsorption was found. The hydrogel prepared with 60 mg itaconic acid and irradiated at 2.00 kGy was found to be the best adsorption system for BSA. The adsorption capacity of acrylamide–itaconic acid hydrogel was found to exceed that of acrylamide hydrogel by more than 80–100%.     

6-苄氨基嘌呤与牛血清白蛋白作用荧光特性的研究

应用荧光光谱法研究了6-苄氨基嘌呤（6-BA）与牛血清白蛋白（BSA）相互作用的荧光特性。测得了6-BA与BSA在10、27、40℃温度下的结合常数KA为：0.21×10^5、1.37×10^5、5.53×10^5L/mol,结合位点数n为：1.0、1.2、1.3。6-BA对BSA内源荧光的猝灭机理主要为静态猝灭,6-BA主要以疏水作用与BSA相互作用,BSA的荧光主要源于色氨酸残基,6-BA对BSA的构象有影响。     

Interaction of magnolol with bovine serum albumin: a fluorescence-quenching study

The interaction of magnolol with bovine serum albumin(BSA) was studied using fluorescence spectroscopy under physiological conditions. The binding constants, K, and the ratio of quantum yields of protein fluorescence for complex and free protein, f, at 298 K, 304 K, and 310 K were obtained; the values were 6.799×10⁵ L mol^–1, 5.541×10⁵ L mol^–1, and 4.344×10⁵ L mol^–1 and 0.17, 0.30, and 0.34, respectively. The standard enthalpy change (H°) and the standard entropy change (S°) were calculated to be –28.53 kJ mol^–1 and 15.88 J mol^–1 K^–1, which indicated that hydrophobic forces played major role in the interaction of magnolol and BSA. The binding average distance between magnolol and BSA (4.32 nm) was obtained on the basis of the theory of Förster energy transfer.     

溴甲酚绿分光光度法测定牛血清白蛋白

在pH 3.3的Britton-Robinson (B-R)缓冲溶液中, 对溴甲酚绿(BCG)与牛血清白蛋白(BSA)相互作用的吸收光谱进行了初步研究. 结果表明: BCG与BSA作用在室温下能迅速结合成复合物, 并且随着BSA的浓度增大, 在444 nm处的吸收峰降低, 618 nm处吸收峰升高并红移至628 nm. 在此波长下测定其复合物的吸光度, 其吸光度的增加值(ΔA)与BSA的质量浓度在8～260 μg/mL范围内呈良好的线性关系(r=0.9996), 检出限为4 μg/mL. 该方法应用于鲜奶粉和液态纯牛奶样品中总蛋白的测定, 回收率分别为92.7%, 95.5%, 结果与考马斯亮蓝G250法基本一致.     

2,4-二硝基苯胺与牛血清白蛋白相互作用的研究

通过荧光和紫外光谱法研究了2,4-二硝基苯胺同牛血清白蛋白(BSA)的相互作用. 2,4-二硝基苯胺对牛血清白蛋白的内源荧光具有强烈的猝灭作用. 二者之间形成不发荧光的复合物是导致荧光猝灭的主要原因. 计算了其结合常数和结合位点数. 紫外光谱法进一步证明了其猝灭机理为静态猝灭. 根据能量转移理论计算了作用距离(3.13 nm). 同步荧光的结果表明2,4-二硝基苯胺的存在改变了牛血清白蛋白的分子构象.     

卡络磺钠与牛血清蛋白荧光光谱的研究

采用荧光光谱法研究了卡络磺钠CSS (Carbazochrome Sodium Sulfonate)与牛血清蛋白(BSA)结合反应的特征, 测定了结合常数(K=1.32×105 L/mol) 和结合位点数(n=1.28). 依据Foster非辐射能量转移理论, 确定了给体-受体间的结合距离(r=4.896 nm)和能量转移效率, 采用同步荧光技术考察了CSS对BSA构象的影响.     

金丝桃苷与牛血清白蛋白相互作用的研究

采用荧光共振能量转移法研究了金丝桃苷与牛血清白蛋白的相互作用.金丝桃苷对牛血清白蛋白(BSA)的荧光猝灭类型是静态猝灭,25℃时的结合位点数为0.5451.并依据F(o)ster非辐射能量转移理论,研究了给体(牛血清白蛋白)--受体(金丝桃苷)间的结合距离R.和能量转移效率E分别为2.04nm和0.66.同时,采用同步...     

二氢氯噻与牛血清白蛋白的相互作用特征

利用荧光技术研究了在生理酸度条件下,二氢氯噻与牛血清白蛋白相互作用,发现二氢氯噻对牛血清白蛋白有较强的荧光猝灭作用,用Stern-Volmer和Line weaver-Burk方程处理荧光猝灭数据,得到了反应的结合常数、结合热力学性质等参数。根据热力学参数确定了该药物与血清白蛋白之间的作用力类型,在此基础上依据福斯特F rster非辐射能量转移理论探讨了二氢氯噻与BSA相互结合时其供体-受体间的距离。与人血清蛋白[1]比较,牛血清白蛋白与二氢氯噻的结合较弱,体现了二氢氯噻与血清蛋白结合的动物间的差异性。同时考察了中药活性成分和金属离子对结合的影响,结果显示甘草次酸对结合的影响较大,提示同时给药时应该注意它们之间的血清药物相互作用。     

秋水仙碱与牛血清白蛋白相互作用的电化学研究

以电化学方法对秋水仙碱与牛血清白蛋白的相互作用进行了研究。在0.3 mol/L H2SO4底液中,秋水仙碱在玻碳电极上产生一不可逆的氧化峰,峰电位为1.18 V(vs.SCE),加入表面活性剂四丁基氯化铵后,秋水仙碱的峰信号得到明显提高。在上述条件下,加入BSA后秋水仙碱的氧化峰电位正移,峰电流下降,峰电流下降值与BSA加入的浓度在1.5×10-7～2×10-6mol/L(r=0.9978)范围内有良好的线性关系,检出限达4.0×10-8mol/L。进一步探讨了秋水仙碱与BSA的结合数和结合常数,得到结合数为1,结合常数为2.40×105L/mol。     

基于分子印迹技术的牛血清白蛋白电位式传感器的研究

以牛血清白蛋白(BSA)为模板,合成了分子印迹聚合物凝胶(MIP),进而制得了以聚氯乙烯(PVC)为支撑膜的BSA电位式传感器。采用直接电位法测得BSA在浓度0.1～1.0 mg/mL范围内与电位呈线性关系。此电极制作简单,可用于BSA的测定。     

Electrochemistry of the interaction of furazolidone and bovine serum albumin

The electrochemical behavior of the interaction of furazolidone (Fu) with bovine serum albumin (BSA) was investigated by cyclic voltammetry and differential pulse voltammetry at a glassy carbon electrode. Fu shows an irreversible reduction at − 0.34 V in pH 4.0 Britton–Robinson buffer (B–R) buffer–10% DMF solution. After the addition of BSA into the Fu solution, the reductive peak currents decreased without any significant shift of the peak potential and the appearance of new peaks. The electrochemical parameters of the interaction system were calculated in the absence and presence of BSA. This electrochemical method was further applied to the determination of BSA samples and the results were in good agreement with the traditional cellulose acetate electrophoresis. The linear dynamic range was between 10.0 and 80.0 mg l^− 1. The detection limit was 7.6 mg l^− 1 and the recoveries were obtained from 97.0% to 104.0%.     

牛血清白蛋白与光谱探针相互作用机理的研究

在酸性条件下研究了考马斯亮蓝光谱探针与牛血清白蛋白结合物的光学性质,探讨了考马斯亮蓝染料和蛋白质的相互作用机理。研究结果表明染料考马斯亮蓝的疏水作用和亲水作用的协调作用以及与生物大分子蛋白质具有相反电荷的静电作用,是光谱探针与生物大分子形成大分子聚集体的必要因素。     

Adsorption of bovine serum albumin at the air/water interface and its effect on the formation of DPPC surface film

The adsorption of bovine serum albumin (BSA) at the air/water interface and its effect on the transport of dipalmitoylphosphatidylcholine (DPPC) to form a surface film were studied with tensiometry, infrared reflection absorption spectroscopy (IRRAS), and ellipsometry. For 1, 10, 100, and 1000 ppm BSA solutions, the steady-state tension ranges from 55 to 50 mN m⁻¹. At pulsating area (at 20 cycles min⁻¹), both the minimum and maximum tensions decrease with increasing bulk concentration. Even though the steady-state tension is similar for 100 and 1000 ppm BSA, IRRAS and ellipsometry results indicate that the adsorbed density is higher for 1000 ppm BSA. For 1000 ppm/1000 ppm BSA/DPPC mixture, the tension behavior was found to be similar to that of 1000 ppm BSA when alone. Results from IRRAS and ellipsometry also demonstrate that BSA is the dominant adsorbed component at the air/water interface. Thus, at 1000 ppm, by adsorbing fast and possibly irreversibly, BSA interferes with the transport and adsorption of DPPC and inhibits its ability to lower the surface tension. However, when DPPC is introduced via a spread monolayer mechanism, DPPC expels partly or completely the adsorbed BSA monolayer and then controls the tension behavior with little or no inhibition by BSA. Thus, the competitive adsorption of DPPC and BSA depends strongly on the path or mechanism of introducing DPPC to the surface and involves path-dependent nonequilibrium adsorption phenomena.     

硫唑嘌呤与牛血清白蛋白相互作用的热力学研究

用荧光光谱法和紫外-可见光谱法研究了在模拟人体生理条件下,硫唑嘌呤和牛血清白蛋白（BSA）结合反应的特征,发现硫唑嘌呤对BSA有较强的荧光猝灭作用,且硫唑嘌呤的紫外吸收光谱和BSA的荧光光谱有一定程度的重叠,由此可得出其作用距离和结合过程的基本热力学参数。     

Spectroscopic investigation of interaction between mangiferin and bovine serum albumin

The mechanism of interaction between mangiferin (MA) and bovine serum albumin (BSA) in aqueous solution was investigated by fluorescence spectra, synchronous fluorescence spectra, absorbance spectra and Fourier transform infrared (FT-IR) spectroscopy. The binding constants and binding sites of MA to BSA at different reaction times were calculated. And the distance between MA and BSA was estimated to be 5.20 nm based on Föster's theory. In addition, synchronous fluorescence and FT-IR measurements revealed that the secondary structures of the protein changed after the interaction of MA with BSA. As a conclusion, the interaction between the anti-diabetes Chinese medicine MA and BSA may provide some significant information for the mechanism of the traditional chinese medicine MA on the protein level to cure diabetes or other diseases.     

胡椒酸丁二醇单脂与牛血清白蛋白相互作用的研究

运用荧光及紫外-可见吸收光谱法研究了胡椒酸丁二醇单酯(简称BPM)与牛血清白蛋白(BSA)的相互作用。实验结果表明,胡椒酸丁二醇单酯与BSA形成基态复合物导致BSA内源性荧光猝灭,猝灭机理主要为静态猝灭和非辐射能量转移,其猝灭速率常数为Kq为1.077×1013L/(mol.s)(25℃)、0.946×1013L/(mol.s)(37℃)。利用荧光猝灭反应测得结合常数KA为2.6×106(25℃)、3.4×106(37℃),结合位点数n为1.30(25℃)、1.33(37℃)。根据Frster能量转移理论得到结合距离r=2.92nm(25℃)、2.66nm(37℃)和能量转移效率E=0.45(25℃)、0.43(37℃)。通过热力学参数计算,确定胡椒酸丁二醇单酯与BSA的相互作用是熵增加和吉布斯自由能降低的自发过程,主要作用力是疏水作用力。