Direct Electrochemistry and Electrocatalysis Behaviors of Glucose Oxidase Based on Hyaluronic Acid-Carbon Nanotubes-Ionic Liquid Composite Film

Multi‐walled carbon nanotubes (MWNTs) were dispersed in the ionic liquid [BMIM][BF₄] to form a uniform black suspension. Based on it, a novel glucose oxidase (GOx)‐hyaluronic (HA)‐[BMIM][BF₄]‐MWNTs/GCE modified electrode was fabricated. UV‐vis spectroscopy confirmed that GOx immobilized in the composite film retained its native structure. The experimental results of EIS indicated MWNTs, [BMIM][BF₄] and HA were successfully immobilized on the surface of GCE and [BMIM][BF₄]‐MWNTs could obviously improve the diffusion of ferricyanide toward the electrode surface. The experimental results of CV showed that a pair of well‐defined and quasi‐reversible peaks of GOx at the modified electrode was exhibited, and the redox reaction of GOx at the modified electrode was surface‐confined and quasi‐reversible electrochemical process. The average surface coverage of GOx and the apparent Michaelis‐Menten constant were 8.5×10⁻⁹ mol/cm² and 9.8 mmol/L, respectively. The cathodic peak current of GOx and the glucose concentration showed linear relationship in the range from 0.1 to 2.0 mmol/L with a detection limit of 0.03 mmol/L (S/N=3). As a result, the method presented here could be easily extended to immobilize and obtain the direct electrochemistry of other redox enzymes or proteins.     

Three novel high performance affinity chromatographic media for the separation of antithrombin III from human plasma.

Novel monodisperse, non-porous, cross-linked poly (glycidyl methacrylate) beads (PGMA) were employed as the support for high performance affinity chromatography. Heparin was covalently attached to PGMA beads by three different coupling methods. Heparin-PGMA-I was prepared by directly coupling amino-groups of heparin with PGMA. Heparin-PGMA-II and III were prepared by the coupling of heparin to amino-PGMA, which was obtained by amination of PGMA. Heparin-PGMA-II was prepared by coupling the carboxyl groups of heparin to amino-PGMA by using water-soluble carbodiimide as coupling reagent, and heparin-PGMA-III was prepared by the reductive amination of heparin and amino-PGMA with sodium cyanoborohydride. The heparin contents of heparin-PGMA-I, II and III were 1.6, 10.2 and 1.0 mg/g beads, respectively. Their affinity capacities for antithrombin III were investigated. Their binding activity to antithrombin III was not proportional to the content of heparin immobilized, and heparin-PGMA-I was the most efficient affinity medium for antithrombin III. The resultant affinity media presented minimal non-specific interaction with other proteins and can be used in a wide pH range. All the three heparin-PGMA beads were exploited for the separation of antithrombin III from human plasma. The purity of antithrombin III obtained was higher than 90%, which was confirmed by high performance size exclusion chromatography.     

Direct electrochemistry of glucose oxidase based on its direct immobilization on carbon ionic liquid electrode and glucose sensing

Direct electrochemistry of glucose oxidase (GOx) has been achieved by its direct immobilization on carbon ionic liquid electrode (CILE) with a conductive hydrophobic ionic liquid, 1-butyl pyridinium hexafluophosphate ([BuPy][PF₆]) as binder for the first time. A pair of reversible peaks is exhibited on GOx/CILE by cyclic voltammetry. The peak-to-peak potential separation (ΔE_P) of immobilized GOx is 0.056 V in 0.067 M phosphate buffer solution (pH 6.98) with scan rate of 0.1 V/s. The average surface coverage and the apparent Michaelis–Menten constant are 6.69 × 10⁻¹¹ mol·cm⁻² and 2.47 μM. GOx/CILE shows excellent electrocatalytic activity towards glucose determination in the range of 0.1–800 μM with detection limit of 0.03 μM (S/N = 3). The biosensor has been successfully applied to the determination of glucose in human plasma with the average recoveries between 95.0% and 102.5% for three times determination. The direct electrochemistry of GOx on CILE is achieved without the help of any supporting film or any electron mediator. GOx/CILE is inexpensive, stable, repeatable and easy to be fabricated.     

A new type of capillary column for open-tubular electrochromatography

A new type of open-tubular C(18) ester-bonded electrochromatographic column was prepared with sol-gel technology, followed by an on-column octadecyl silylation reaction. Glycidoxypropyltrimethoxysilane, a widely used and important silane agent, was used as the sol-gel precursor to form a thin coating layer on the wall of the fused-silica capillary. The C(18) groups were introduced into the coating layer by on-column esterification reaction with stearic acid. The electrochromatography behavior of the column was evaluated in terms of the separation of peptides. A high efficiency of 4.8x10(5) plates/m was achieved for a basic pentapeptide using the C(18 )ester-bonded column. In comparison with bare capillaries and glycidoxypropyltrimethoxysilane sol-gel-coated capillaries, the C(18) ester-bonded column showed the best separation of a mixture of seven pentapeptides under identical conditions of buffer, pH, and applied voltage.     

Ex vivo identification of circulating tumor cells in peripheral blood by fluorometric “turn on” aptamer nanoparticles

The detection of the circulating tumor cells (CTCs) detached from solid tumors has emerged as a burgeoning topic for cancer diagnosis and treatment. The conventional CTC enrichment and identification mainly rely on the specific binding of the antibodies on the capture interface of the magnetic nanoparticles with the corresponding biomarkers on the cell membranes. However, these methods could easily generate false-negative results due to the extremely low concentration of CTCs and the internal heterogeneity of the tumor cells. Herein, with the aim of selectively identifying CTCs and improving the detection accuracy in peripheral blood, we designed the fluorometric “turn on” Au nanoparticles (DHANs) with the modification of a tumor-targeted moiety, dehydroascorbic acid (DHA) and a fluorometric aptamer, which could be “switched-on” by an over-expressed intracellular protein, namely hypoxia-inducible factor-1α (HIF 1α). This novel nanoformulated detection platform demonstrated the great capacity for visualizing various CTCs in peripheral blood with significantly improved detection efficiency and sensitivity. As a result, the nanoplatform has a great potential to be further applied for CTC detection in vitro or in vivo, which holds promise for extensive CTC studies.

The detection of the circulating tumor cells (CTCs) detached from solid tumors has emerged as a burgeoning topic for cancer diagnosis and treatment.     

改进遗传算法用于未知组分数的重叠色谱峰的解析

按照指数修正的Gauss卷积色谱峰模型，构造了结合模拟退火及变长染色体的改进遗传算法，并结合爬山法，可以方便快捷地进行数目未知的重叠色谱峰的精确解析；此法成功地应用于大鼠脑微透析液氨基酸定量分析中，解析结果良好。     

铈钼氧化物表面氧性质和催化性能

在甲苯选择性氧化制苯甲醛反应中,Mo基氧化物是一类重要的催化剂[1]．通常的认识是反应物与催化剂表面晶格氧作用,并通过催化剂本身的还原和氧化的循环过程促使反应进行。生成产物．因此,催化剂表面不同氧物种的热脱附性能应与催化反应性能密切相关．对于Ce-Mo氧化物的TPD-MS研究,尚未见文献报导．为了能获得该方面的信息,本文应用程序升温脱附-质谱检测（TP-MS）联用技术,对Ce-Mo氧化物样品进行了表面氧TPD谱测定和动力学参量等计算,并试图与其催化性能进行关联．1实验部分1．1样品的制备和表征分别将一定质量的硝酸铈铵和仲…     

Reaction mechanism of simultaneous catalytic removal of NOx and diesel soot particulates

Reactions of diesel soot and NOx with and without O₂ were carried out over CuFe₂O₄ catalyst. The ignition temperature of soot with the NO+O₂ feed was lower than that in O₂ or NO but close to those in NO₂ and NO₂+O₂, indicating the implication of NO₂ especially in decreasing the ignition temperature. On the other hand, the reduction of NOx into N₂ was enhanced by coexisting O₂. Based on these results and mechanisms of O₂-soot and NO-soot reactions, the possible reaction mechanism of the simultaneous NOx-soot removal with the NO+O₂ feed has been proposed.     

MoO3-x/PCN的原位合成及其增强光催化产氢性能的研究

本文通过简单的一步浸渍煅烧法原位合成了氧化钼纳米晶/聚合物氮化碳复合光催化剂,该不含铂基助催化剂的氧化钼修饰聚合物氮化碳光催化剂在可见光照射下表现出增强的光催化产氢性能,最高产氢速率为15.6 μmol/h,是普通聚合物氮化碳样品的3倍以上. 相应的结构与性能的分析表明,与后浸渍法不同,在原位生长过程中高分散的超小氧化钼纳米晶体与聚合物氮化碳之间形成了紧密的耦合界面结构,可见光产氢活性的提升源自高分散的超小氧化钼纳米晶与聚合物氮化碳之间形成的紧密界面,以及该界面结构形成的肖特基结带来的有效电荷载流子转移.     

β-羧乙基(或α-甲基乙基)锗三氯化物晶体和分子结构及其质谱分析

有机锗化合物的抗癌等广泛生物活性已引起人们对其研究的兴趣。β-羰乙基锗倍半氧化物(Ge-132)的生物活性已有广泛研究,对其衍生物合成及性质研究亦受到重视。作为合成这类衍生物的中间体,β-羧烃基锗三氯化物的结构和性质报道较少。我们制备了两种β-羧烷基锗三氯化物晶体,测定了其晶体和分子结构,研究了质谱裂解机理,讨论了结构和性质问的关系。