镀金和碳纳米管修饰金电极上吸附态葡萄糖氧化酶比活性的EQCM研究

采用石英晶体微天平(EQCM)技术监测了裸金电极、镀金和碳纳米管修饰金电极上葡萄糖氧化酶(GOD)的吸附过程. 通过EQCM测量吸附固定的GOD质量, 并实时检测酶反应产物H2O2的氧化电量, 求算了各表面上吸附态GOD的比活性(ESAi). 结果表明, 各表面上均可吸附一定的GOD, 且吸附态GOD均有一定的酶活性; 修饰CNTs可增大酶吸附量和酶电极对葡萄糖的响应电流, 但ESAi随CNTs修饰量的增大而降低; Au电极上电镀金后, 酶吸附量和酶电极对葡萄糖的响应电流亦增大, 但ESAi与裸金电极上的基本一致.     

Pt电极上吸附原子对仲丁醇电催化氧化性能的影响

运用电化学循环伏安和石英晶体微天平研究了HClO4溶液中仲丁醇在Pt电极及以Sb和S吸附原子修饰的Pt(Pt/Sbad和Pt/Sad)电极上的电催化氧化过程 .从电极表面质量变化可以看出 ,仲丁醇的氧化与电极表面的氧物种有着极其密切的关系 .Pt电极表面Sb吸附原子可在较低的电位下吸附氧 ,明显提高仲丁醇的氧化活性 .与Pt电极相比 ,Sb吸附原子修饰的Pt电极使仲丁醇氧化的峰电位负移约 10 0mV .相反 ,Pt电极表面S吸附原子的氧化会消耗表面氧物种 ,抑制仲丁醇的氧化 .从电极表面质量变化提供了吸附原子电催化作用的数据     

电化学石英晶体微天平研究界面电场对DNA杂交的影响

采用电化学石英晶体微天平, 现场监测不同界面电场下完全匹配的靶标DNA和不完全匹配的靶标DNA分别与寡聚核苷酸探针分子杂交的过程. 结果表明, 电极表面荷正电时DNA表观杂交效率比电极表面荷负电时高, 但假阳性比较显著; 而电极表面荷负电时能有效地抑制错配杂交. 探讨了引入界面电场后探针分子取向和微观作用力对DNA杂交的影响.     

Electrochemical piezoelectric quartz crystal impedance study on the interaction between concanavalin A and glycogen at Au electrodes

The carbohydrate research has emerged as a "new frontier" in chemical/biological field. The binding of lectin with carbohydrate is one of the important courses of life activities. The report studies concanavalin A (Con A)-glycogen interaction on gold electrode surfaces by electrochemical piezoelectric quartz crystal impedance (EPQCI) method. The piezoelectric quartz crystal (PQC) parameters, resonant frequency shift (Deltaf(0)) and the motional resistance change (DeltaR(1)), and the electrochemical impedance (EI) parameters, electrolyte resistance change (DeltaR(s)) and the double layer capacitance change (DeltaC(s)), were measured and discussed simultaneously. Two methods were adopted for measuring the Con A-glycogen association. Based on EPQCI measurement during Con A reaction with glycogen adsorbed on Au electrode, association constant K(a) and the amount of the binding sites s calculated are 1.48 x 10(6) M(-1) and 4.09, respectively. Based on single PQC measurement of glycogen reaction with Con A assembled on Au electrode, K(a) was estimated to be 1.26 x 10(6) M(-1).     

卵磷脂抗石英毒作用的研究

本文采用家兔肺泡巨噬细胞(AM)体外培养法,以细胞内游离钙浓度([Ca~(2+)]_i)、细胞存活率、乳酸脱氢酶(LDH)和酸性磷酸酶(ACP)活性为指标,观察了卵磷脂、脑磷脂及现用防治硅肺药物克矽平(PVPNO)、柠檬酸铝等抗石英毒效果。结果表明:卵磷脂在所试各药物中效果最佳.初步探讨了卵磷脂拮抗石英细胞毒性的机理.卵磷脂有成为防治硅肺药物的可能性.     

Aspects of thermal conductivity relative to heat flow

Summary The various techniques and methodologies of thermal conductivity measurement have been conventionally based on the determination of the rate of directional heat flow through a material having a unit temperature differential between its opposing faces. The constancy of this rate depends on the material density, its thermal resistance and the heat flow path itself. The last of these variables contributes most significantly to the true value of steady-state axial and radial heat dissipation depending on the magnitude of transient thermal diffusivity along these directions. The purpose of this paper is to exemplify the above features by defined parameters of heat flow measurement by existing methodologies. No new method is proposed here. Importantly, the relationship between the rate of heat transfer, total heat transferred and thermal conductivity at a given temperature under steady-state conditions for a fixed heat flow path will be illustrated.     

The preparation of thick-film glass capillary columns

A detailed method for the routine preparation of glass capillary columns is presented. The method consists of coating a glass tube with quartz powder prior to pulling the tube into a capillary. The inner surface of the capillary consists of an even distribution of quartz particles fused to the walls. This surface has been found readily deactivated by standard procedures and ideal for the preparation of thick-film glass capillary columns. The method has been thoroughly tested in two independent laboratories to ensure that the procedures described are reproducible.     

Biomimetic piezoelectric quartz sensor for caffeine based on a molecularly imprinted polymer

A piezoelectric quartz sensor coated with molecularly imprinted polymer (MIP) for caffeine was developed. The MIP was prepared by co-polymerizing methacrylic acid (MAA) and ethylene glycol dimethacrylate (EDMA) in the presence of azobis(isobutyronitrile) as initiator, caffeine as template molecule, and chloroform as solvent. The MIP suspension in polyvinyl chloride/tetrahydrofuran (6:2:1 w/w/v) solution was spin coated onto the surface of the electrode of a 10 MHz AT-cut quartz crystal. The sensor exhibited a linear relationship between the frequency shift and caffeine concentration in the range of 1×10^–7 mg mL^–1 up to 1x10^–3 mg mL^–1 [correlation coefficient (r)=0.9935] in a stopped flow measurement mode. It has a sensitivity of about 24 Hz/ln(concentration, mg mL^–1). A steady-state response was achieved in less than 10 min. The performance characteristic of the sensor shows a promising and inexpensive alternative method of detecting caffeine. Surface studies were carried out for the reagent phase of the sensor using SEM, AFM, and XPS analysis in order to elucidate the imprinting of the caffeine molecule. The SEM micrograph, AFM image, and XPS spectra confirmed the removal of caffeine by Soxhlet extraction in the imprinting process and the rebinding of caffeine to the MIP sensing layer during measurement.     

Transport of ionic charge and solvent in poly(3-octylthiophene) films: An electrochemical quartz crystal microbalance study

The results of a study of poly(3-octylthiophene) films with the aid of an electrochemical quartz microbalance are presented. The effect of the nature of the electrolyte anion on the determined weights of mobile species that are transported through the film/electrolyte interface is discussed. The obtained results point to a substantial role played by the solvent transport in the course of the electrode reaction. The results concerning the influence exerted by the electrode material on the observed regularities are presented.     

A novel piezoelectric immunosensor for the detection of malarial Plasmodium falciparum histidine rich protein-2 antigen

A novel piezoelectric (PZ) immunosensor for the direct detection of malarial Plasmodium falciparum histidine rich protein-2 (PfHRP-2) antigen was developed. The mixed self-assembled monolayers (SAMs) of thioctic acid and 1-dodecanethiol were formed on gold surface of quartz crystal. Cyclic voltammetry, electrochemical impedance spectroscopy and surface Raman spectroscopy techniques were used to characterize the mixed SAMs. The rabbit anti-PfHRP-2 antibodies were coupled on mixed SAM modified gold surface of quartz crystal via NHS/EDC activation method. The PZ immunosensor was applied to detect PfHRP-2 in the linear range of 15-60 ng/ml with a detection limit of 12 ng/ml. It was also found that even after 14 days of storage, 50% of the activity still remained. Clinical human serum samples were tested with this method, and the results were in agreement with those obtained from commercially available ICT kit (NOW^® Malaria).