Sonocatalytic damage of bovine serum albumin (BSA) under ultrasonic irradiation by mixed TiO2/SiO2 powder

BACKGROUND: In order to effectively damage some biomolecules under ultrasonic irradiation, a mixed TiO₂/SiO₂ powder with high catalytic activity and selectivity was used as a sonocatalyst. RESULTS: The mixed TiO₂/SiO₂ powder heat treated at 450 °C for 30 min was adopted as a sonocatalyst and the damage to BSA molecules under ultrasonic irradiation was assessed. In addition, the effects of such variables as molar ratio of TiO₂ and SiO₂, treatment temperature and time, ultrasonic irradiation time, catalyst amount, solution acidity, ionic nature and strength, ultrasonic irradiation power and D₂O concentration on the damage to BSA molecules were studied by means of UV‐visible and fluorescence spectra. The results showed that the degree of damage was aggravated by an increase in ultrasonic irradiation time, catalyst amount, solution acidity, ultrasonic irradiation power and D₂O concentration, but was reduced by an increase in ionic strength. CONCLUSION: The results indicated that the mixed TiO₂/SiO₂ powder displayed higher activity and selectivity compared with nano‐sized TiO₂ and SiO₂ powders during the sonocatalytic damage of BSA. The extent of the damage decreased in the order TiO₂/SiO₂ > nano‐sized TiO₂ > nano‐sized SiO₂. These results are of great significance for applying sonocatalytic methods to treat tumours. Copyright © 2008 Society of Chemical Industry     

光谱法研究迷迭香酸和牛血清白蛋白的相互作用

利用荧光和圆二色光谱研究了迷迭香酸(RA)与牛血清白蛋白(BSA)之间的相互作用.通过荧光猝灭测得在301、308和315 K时,RA与BSA的结合常数K分别为4.18×10~4、3.62×10~4和2.52×10~4 L/mol,表明RA与BSA间具有较强的结合作用,属于静态猝灭.热力学参数计算结果表明RA与BSA相互作用力以范德华力及氢键作用力为主.圆二色光谱、红外及拉曼光谱、荧光同步光谱研究表明相互作用后BSA的二级结构发生微小变化.此外,常见金属离子对结合有较为显著的影响.     

Tailorable polyelectrolyte protein complex based on poly(aspartic acid) and bovine serum albumin

Protein–polyelectrolyte complexes (PPC) are playing an important role in a variety of chemical and biological processes, such as protein separation, enzyme stabilization, and polymer drug delivery. The present investigation is focused on evaluation of the PPC formation between a synthetic polypeptide (poly(aspartic acid) – PAS) and a natural protein (bovine serum albumin – BSA). The PPC obtained from PAS and BSA in different ratio was investigated by corroboration of various techniques of characterization as: spectroscopy, microscopy, thermogravimetric analysis, dynamic light scattering (DLS), and zeta potential determination, measurements which were performed in static and/or dynamic conditions. The static contact angle of the sample films was also determined in order to evaluate the changes brought upon surface free energy of the prepared PPCs in interdependence with the complexes composition. The critical conditions for complex formation in BSA–polyelectrolyte systems were underlined. The phenomenon was better evidenced in case of a ratio of 1/1 wt between the two polymers, both in static and/or dynamic conditions.     

Synthesis and characterization of poly(N-vinyl pyrrolidone-alt-maleic anhydride): Conjugation with bovine serum albumin

Alternate N-vinyl pyrrolidone/maleic anhydride (NVPMA) copolymers were obtained by radical solution polymerization in dioxane with various MA contents in the monomer feed. The conversion of each monomer was monitored by proton nuclear magnetic resonance spectroscopy (¹H NMR), and the kinetics investigation showed that both monomers had identical polymerization rates if both monomers were present in the reaction mixture. The presence of excess NVP in the polymerization medium increased the kinetics of the polymerization and the molar masses of the resulting polymers. This increase was attributed to a cosolvent effect due to NVP, which is a better solvent for the polymer than dioxane. The hydrolysis rate constant of the polymers increased with pH, and NVPMA copolymers were more prone to hydrolysis (by a factor 10) than the methyl vinyl ether ones. Finally, the immobilization of bovin serum albumin (BSA) was investigated. A 25 mM phosphate buffer (pH 5.5) was the best medium to covalently bind 5 BSA molecules onto a 29 kDa NVPMA copolymer and 13 BSA molecules onto a 58 kDa sample, with grafting efficiencies > 90%. Noncovalent interactions with the hydrolyzed form of the polymer and BSA occured at pHs lower than the isoelectric point of BSA, and the resulting complexes were insoluble in water. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3327–3337, 2001     

6-甲基-4-(4-氨基苯基)-5-乙氧基羰基-3,4-二氢嘧啶酮的晶体结构及与牛血清白蛋白的相互作用

本文合成了6-甲基-4-(4-氨基苯基)-5-乙氧基羰基-3,4-二氢嘧啶酮(AEMD),通过X射线单晶衍射对结构进行了确认。该晶体属于单斜晶系,P2(1) / c空间群,晶胞参数a=11.237(4)nm,b=5.799(2)nm,c=22.394(7)nm,α=90o,β=91.048(5)o,γ= 90o,Z=4。用荧光光谱法研究了AEMD与牛血清白蛋白(BSA)的相互作用,结果表明：AEMD对BSA有荧光猝灭作用;热力学参数(ΔH?0 and ΔS?0)表明：AEMD与BSA之间的主要作用力为氢键和范德华力;根据F?rster’s非辐射能量转移理论,AEMD与BSA的结合距离为2.19nm;同步荧光结果表明：AEMD使BSA分子构象发生了改变。     

Fabrication and characterization of TiO2/poly(dimethyl siloxane) composite fibers with thermal and mechanical stability

The mechanical stability of titania (TiO₂) nanofibers was improved by fabricating TiO₂/poly(dimethyl siloxane) (PDMS) composite fibers using a combination of hybrid electrospinning and sol‐gel methods, followed by heat treatment at 250°C for 3 h. The compositions (90/10, 80/20, and 70/30, w/w) of the TiO₂/PDMS composite fibers were varied by adjusting the flow rate of the PDMS sol with the flow rate of TiO₂ sol fixed. There was no significant change in morphology and average diameter of the as‐spun TiO₂/PDMS fibers after heat treatment. Both the tensile strength and modulus of the TiO₂/PDMS composite fibers increased gradually with increasing PDMS content up to 30 wt %. In addition, from the photo‐degradation reaction of methylene blue, the photocatalytic activity of TiO₂/PDMS composite fibers was strongly dependent on the TiO₂ content (%) in the composite fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

蒙脱石/TiO2复合材料制备及其光催化性能研究

以蒙脱土和钛酸丁酯为原料,采用溶胶凝胶法制备出蒙脱石/TiO2复合材料,利用XRD、SEM、光催化亚甲基蓝溶液对其物相组成、晶体结构、微观结构和光催化性能进行了研究.结果表明:TiO2以锐钛矿相分布于蒙脱石的层间域和表面,并使蒙脱石d001有不同程度的增大.蒙脱石/TiO2复合材料的加入量和Ti/蒙脱石比值、亚甲基蓝溶液的初始质量浓度对蒙脱石/TiO2复合材料的吸附和光催化效率均有影响.     

膨胀石墨／二氧化钛复合材料的制备与性能研究

本文主要研究了膨胀石墨／二氧化钛复合材料的制备,采用直接膨化的膨胀石墨与钛酸丁酯的醇溶液混合法制备膨胀石墨／二氧化钛复合材料,并分析了膨胀石墨／二氧化钛复合材料的物理性能,以甲基橙溶液的光催化降解反应为探针反应,评价了该复合材料的催化性能。     

Electrochemical cleaning of microporous metallic filters fouled with bovine serum albumin and phosphate under low cross-flow velocities

A three-electrode electrochemical cell has been designed to test the cleaning efficiency of applying potentials or currents to 0.2 m pore size silver membranes fouled with bovine serum albumin and phosphate under low cross-flow velocities. It was found that with the improved electrochemical efficiency of the three-electrode design (compared to two-electrode cells) only relatively small current densities (about –40 A cm^–2) needed to be applied in order to charge the membranes sufficiently to cause the reduction of water. The best results for electrochemically cleaning fouled membranes were obtained when negative currents were applied to membranes in a moderate strength acid environment. It was found that the interfacial pH changes associated with the reduction of water were important in cleaning the membranes in addition to the agitation action of bubbles of hydrogen gas.     

Study of the adsorption process of bovine serum albumin on passivated surfaces of CoCrMo biomedical alloy

Adsorption of bovine serum albumin (BSA) on CoCrMo surface was studied by electrochemical techniques in order to determine the mechanism of protein adsorption at different surface conditions (which are reached by considering different passivation times) in phosphate buffered solution (PBS). At open circuit potential (OCP), adsorption kinetic was influenced by surface passivation when passivation time was lower than 1 h, whereas, at higher passivation times, no apparent modification in the kinetic mechanisms of adsorption was observed. On the other hand, at a passive applied potential, the BSA addition decreased the passivation kinetics of the process at all the passivation times.     

牛血清白蛋白纳米球接枝杨梅单宁的制备以及吸附去除水体中Pb2+的性能

采用去溶剂法和杨梅单宁-戊二醛固化接枝制备得到杨梅单宁（BT）接枝牛血清白蛋白（BSA）纳米球（BSA-BT-NSs）吸附材料，并系统探讨了其在不同吸附条件下对水体中Pb²⁺的吸附去除性能。研究结果表明：50%用量杨梅单宁（基于BSA-NSs量）接枝固化得到的BSA-BT-NSs具有较好的球形结构和良好的分散性。在吸附实验中，Pb²⁺初始浓度为250mg/L、pH 5.0、温度为298K 条件下吸附20min，BSA-BT-NSs（0.4g/L）对Pb²⁺的吸附效果最佳，最大吸附容量为76mg/g，优于多数同类型吸附材料。BSA-BT-NSs对Pb²⁺吸附过程符合Langmuir方程和准二级吸附动力学模型，且吸附后的BSA-BT-NSs经0.1mol/L 硝酸进行解吸取得了92.04％的良好解吸效果，并可再次重复使用。进一步分析其Pb²⁺吸附机理，表明BSA-BT-NSs中的氨基氮原子、羟基和羧基氧原子作为电子供体参与了与Pb²⁺的空轨道发生配位作用。     

TiO2/SiO2复合薄膜的制备及其自清洁性能

利用热陈化法得到的纳米TiO2粒子及SiO2聚合物胶粒通过浸渍-提拉技术制备了具有自清洁功能的TiO2/SiO2复合薄膜。考察了SiO2的复合比例对薄膜的表面形貌、透光率、光致亲水及自清洁性能的影响。随着SiO2复合体积分数的增大,薄膜的表面粗糙度、可见光透过率、光致亲水及自清洁性能显示了相似的变化规律。即在V(SiO2)=25%左右时,薄膜的各项特性或性能达到最大值或最小值。该薄膜在室外放置28天后,仍能显示超亲水性能。     

Photocatalytic activity of AgBr/TiO2 in water under simulated sunlight irradiation

In this paper, the synthesis of AgBr/TiO₂ catalyst and the photocatalytic activity in water under simulated sunlight irradiation were studied. The influence of AgBr content in catalyst and the incident light intensity on the degradation of methyl orange (MO) was investigated. It was found that the initial reaction rate constant was dependent on the relative levels of AgBr content and incident light intensity, ranging between 0.008 min⁻¹ and 0.023 min⁻¹. At higher levels of AgBr content (>9 wt%), MO degradation was exclusively dependent on the incident light intensity, which implied that the excessive AgBr in catalyst had negligible effect on catalyst activity. However, at lower AgBr contents, the reaction rate increased with the increase of incident light intensity, and eventually reached a plateau level, indicating that the degradation of MO was limited by AgBr content. The results from powder X-ray diffraction (XRD) analysis showed that more than 80% of AgBr remained intact after 14 h of irradiation, although metallic silver was also detected.     

聚对苯撑乙烯类共聚物／TiO2复合材料光物理性能的研究

两种经过化学修饰的PPV（聚对苯撑乙烯）类共轭高分子共聚物分别与纳米TiO2复合，作为有机／无机复合材料进行研究。这两 人聚物在乙醇、二氯甲烷溶液中分别与以Sol-Gel法、反胶束法制得的TiO2共混得到均匀分散的体系而不出现相分离，用共聚物与TiO2的复合液可以在石英基底上制成均匀的复合膜，结果表明，高聚物／TiO2复合物的光物理特性与单纯的高聚物相比呈现明显的差异；不同粒径的纳米TiO2以复合物性能的影响不同；中间苯环的聚代基对共聚物的性质影响明显，共轭高分子与纳米TiO2复合涂膜后其发光性能明显改善，有作为发光器件的应用前景。     

Separation of bovine serum albumin (BSA) using γ‐Al2O3–clay composite ultrafiltration membrane

BACKGROUND: Ceramic membranes have received more attention than polymeric membranes for the separation and purification of bio‐products owing to their superior chemical, mechanical and thermal properties. Commercially available ceramic membranes are too expensive. This could be overcome by fabricating membranes using low‐cost raw materials. The aim of this work is to fabricate a low‐cost γ‐Al₂O₃–clay composite membrane and evaluate its potential for the separation of bovine serum albumin (BSA) as a function of pH, feed concentration and applied pressure. To achieve this, the membrane support is prepared using low‐cost clay mixtures instead of very expensive alumina, zirconia and titania materials. The cost of the membrane can be further reduced by preparing a γ‐alumina surface layer on the clay support using boehmite sol synthesized from inexpensive aluminium chloride instead of expensive aluminium alkoxide using a dip‐coating technique. RESULTS: The pore size distribution of the γ‐Al₂O₃‐clay composite membrane varied from 5.4–13.6 nm. The membrane was prepared using stable boehmite sol of narrow particle size distribution and mean particle size 30.9 nm. Scanning electron microscopy confirmed that the surface of the γ‐Al₂O₃–clay composite membrane is defect‐free. The pure water permeability of the support and the composite membrane were found to be 4.838 × 10^?6 and 2.357 × 10^?7 m³ m^?2 s^?1 kPa^?1, respectively. The maximum rejection of BSA protein was found to be 95%. It was observed that the separation performance of the membrane in terms of flux and rejection strongly depends on the electrostatic interaction between the protein and charged membrane. CONCLUSION: The successively prepared γ‐Al₂O₃‐clay composite membrane proved to possess good potential for the separation of BSA with high yield and could be employed as a low cost alternate to expensive ceramic membranes. Copyright © 2009 Society of Chemical Industry     

TiO2/AC复合材料的制备及其对孔雀石绿的光催化降解

以活性炭为载体,用溶胶-凝胶法制备了不同TiO2负载量的TiO2/AC复合光催化剂,运用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和红外光谱仪(FT-IR)对该催化剂进行表征.探讨了TiO2的负载量、光催化剂质量浓度、溶液的初始质量浓度等因素对孔雀石绿降解效率的影响,并对催化剂进行了回收再生实验.结果表明,TiO2负载量为30％时的复合催化剂为锐钛矿相,对孔雀石绿的降解具有良好的光催化活性,且回收7次重复使用降解效果仍在95％以上.     

Preparation of bovine serum albumin‐imprinted calcium polyacrylate/alginate hybrid microspheres via Ca2+ crosslinking

Macromolecularly imprinted calcium polyacrylate/alginate hybrid polymer microspheres with the imprinting of bovine serum albumin were prepared with sodium alginate and sodium polyacrylate by using CaCl₂ as a gelling agent in inverse‐phase suspension. Infrared spectrum and conductance titration demonstrated that hybrid components were produced in these microspheres. Rebinding isotherms of the microspheres proved a greater bovine serum albumin affinity for imprinted microspheres relative to nonimprinted ones. Selectivity tests indicated that calcium polyacrylate/alginate hybrid polymer microspheres exhibited good recognition properties for the template protein with the separation factor over 5.30 comparing to the competitive proteins with a similar M_w. The influence of cross‐linker CaCl₂ concentration on the imprinting efficiency (IE) and rebinding capacity was researched. It was found that the cross‐linking density and imprinting efficiency of the hybrid hydrogel could be improved simultaneously. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

多孔TiO_2/SiO_2复合薄膜的制备及其超亲水性机理

采用溶胶-凝胶法,以钛酸四丁酯和正硅酸乙酯为前驱体,利用乙酰丙酮和二乙醇胺为络合剂,制备多孔TiO2/SiO2复合薄膜。通过扫描电子显微镜(SEM)、原子力显微镜(AFM)、傅里叶变换红外光谱(FTIR)、X射线衍射分析(XRD)、接触角测试仪(WCA)等对薄膜的结构和性能进行了表征。结果表明,TiO2/SiO2复合薄膜表面相对孤立或连通的孔结构是由缩聚反应诱导的相分离以及溶胶-凝胶转化过程同步作用产生的。多孔复合薄膜具有优异的超亲水性能,自然条件下与水接触角仅为2.5°,而普通致密TiO2薄膜在相同条件下接触角为19.3°。复合薄膜的超亲水性是由多孔结构和SiO2复合的共同作用产生,受到表面微观形貌和表面化学组成(羟基含量)的共同影响。     

聚硅硫酸钛制备复合光催化剂及降解甲基橙的研究

以无机钛盐、硅酸盐为原料,制备了聚硅硫酸钛絮凝剂,然后利用其水溶液水解产物制备复合光催化剂,考察了钛与硅摩尔比、水解pH值、调节pH值所用碱的种类、煅烧温度和煅烧时间对该复合光催化剂降解甲基橙时活性的影响,并利用扫描电镜（SEM）和X射线衍射（XRD）对其进行了物性测试分析。结果表明：n（Ti）：n（Si）=12：1的聚硅酸硫酸钛,以NH3.H2O调节pH值,在pH值为6时水解,产物在650℃煅烧1.5h后制得的复合光催化剂活性最高,当其投加量为0.5g.L-1时,光催化反应30min后,甲基橙的脱色率可达100%。物性分析表明,聚硅钛制备的复合光催化剂是一种以锐钛矿为主、分散均匀的纳米级球形颗粒。     

微波辐射离子液体中TiO2/PS-PEMA复合材料的制备及其性能

以钛酸丁酯为前驱物,在离子液体([Bmim]BF_4)中采用微波辐射加热法合成了TiO_2/PS-PEMA复合材料。通过测试复合材料在乙酸乙酯中的吸光度以及对甲基橙溶液的降解率,考察了离子液体用量、微波功率、反应温度和反应时间等因素对复合材料分散性和光催化活性的影响。结果表明,制备TiO_2/PS-PEMA复合材料的最佳条件为:离子液体用量2.0 mL,微波功率700 w,反应温度70℃,反应时间45 min和引发剂过硫酸钾用量0.10 g。制得的复合材料亲油性大大提高,在乙酸乙酯中有较好的分散性,对甲基橙具有较高的光催化降解活性。