An analysis of avidin, biotin and their interaction at attomole levels by voltammetric and chromatographic techniques

The electroanalytical determination of avidin in solution, in a carbon paste, and in a transgenic maize extract was performed in acidic medium at a carbon paste electrode (CPE). The oxidative voltammetric signal resulting from the presence of tyrosine and tryptophan in avidin was observed using square-wave voltammetry. The process could be used to determine avidin concentrations up to 3 fM (100 amol in 3 l drop) in solution, 700 fM (174 fmol in 250 l solution) in an avidin-modified electrode, and 174 nM in a maize seed extract. In the case of the avidin-modified CPE, several parameters were studied in order to optimize the measurements, such as electrode accumulation time, composition of the avidin-modified CPE, and the elution time of avidin. In addition, the avidin-modified electrode was used to detect biotin in solution (the detection limit was 7.6 pmol in a 6 l drop) and to detect biotin in a pharmaceutical drug after various solvent extraction procedures. Comparable studies for the detection of biotin were developed using HPLC with diode array detection (HPLC-DAD) and flow injection analysis with electrochemical detection, which allowed biotin to be detected at levels as low as 614 pM and 6.6 nM, respectively. The effects of applied potential, acetonitrile content, and flow rate of the mobile phase on the FIA-ED signal were also studied.     

低钴AB5型稀土系贮氢电极合金的研究

为了进一步降低AB5型混合稀土系贮氢合金的成本,采用Cr,Si,Cu替代Co和调节化学计量比的方法制备低钴AB5型贮氢合金。结果表明:3种取代元素在寿命方面的效果依次为Si>Cr>Cu,在放电容量和活化性能方面依次是Cu>Cr>Si。Cr,Cu,Si只有少量的替代才可能发挥其有利影响;通过非化学计量比的调节,低钴混合稀土系贮氢电极合金的放电容量、活化性能及倍率放电能力都能较好地达到实用要求,但是循环寿命有待提高。     

Fluorescence Analysis in Microarray Technology

Fluorescence has been the preferred choice for data quantification in biomedical microarray formats since their earliest days. As much as the formats have grown and evolved over the years, the methods in optical analysis have become ever more sophisticated and complex in order to produce more and better output. This review will provide an insight into the most common methods and the state-of-the-art of all areas in microarray fluorescence analysis. Starting with an overview on microarray formats with a focus on their demands on the readout, the most common and useful organic fluorescent stains are discussed before proceeding on to other approaches; the use of semiconductor nanocrystals (quantum dots), polymer and silica nanoparticles and fluorescent proteins. Ways to enhance the intrinsically low signal on biochips have become increasingly important as they offer a sound approach towards the detection of low concentration sample content. The three main categories are presented: amplification using DNA, enzymes, and dendrimers. As much diversity as on the microarrays themselves can be found at the detection device. Standard optical microarray detectors, and non-standard methods using fluorescence anisotropy, fluorescence lifetime imaging (FLIM) and fluorescence resonance energy transfer (FRET), and their advantages and disadvantages are discussed.     

液相组合合成的纯化方法

综述了近8年来液相平行合成和组合合成中应用的不同技术, 包括可溶性载体、氟合成技术、离子液体、固相试剂树脂以及低聚乙烯二醇(OEG)衍生物的应用等几方面内容. 论述了它们的基本原理以及相关的应用实例, 并着重强调了目标化合物的分离纯化方法.     

基于支持向量机的羰基化合物红外光谱研究

设计了一个4层分等级分类系统，通过支持向量机技术对羰基化合物的红外光谱成功地进行了信息分类和提取，并与人工神经网络进行比较，结果表明：支持向量机对羰基类化合物红外光谱分类效果优于人工神经网络；另外详细探讨了表征酰胺类化合物的特征光谱峰片段对识圳伯仲叔酰胺的影响，证明了酰胺的N-H伸缩振动峰对识别伯仲叔酰胺贡献最大，为构建红外光谱智能解析系统提供了定量依据。     

Piezoelectric Fiber－optic Spectroelectrochemistry──A New Technique of Spectroelectrochemistry in Combination With Piezoelectric Quartz Crystal Detection

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Coated-wire organic ion-selective electrodes in titrations based on ion-pair formation : Determination of arenediazonium salts with sodium tetraphenylborate

Titrimetric determinations of arenediazonium salts can be based on ion-pair formation between the diazonium cation and tetraphenylborate. Titrations are done under cooling with ice and are followed potentiometrically with organic ion-selective electrodes comprising PVC membranes plasticized with polar solvents and coated on aluminium wires. The method was tested in determinations of arenediazonium salts derived from 20 aromatic amines, including aniline, toluidines, naphthylamines and their derivatives. Except for compounds containing hydrophylic groups such as —COOH and —OH, the potentiometric titration curves have well defined end-points. The results are reproducible, with relative standard deviations in the range 0.4–1.4% at the millimolar level. The method can be used for reliable determinations of arenediazonium salts in analytical control of azo dyestuff production.     

Application of an Ion Beam Technique for the Design of Visible Light-Sensitive, Highly Efficient and Highly Selective Photocatalysts: Ion-Implantation and Ionized Cluster Beam Methods

As a new concept for the design of effective photocatalysts, an ion beam technology using accelerated metal ions, a metal ion implantation and an ionized cluster beam (ICB) method, have been applied to design unique photocatalysts. The metal ion implantation of TiO₂ and Ti-containing zeolites with highly accelerated metal ions (V⁺, Cr⁺, etc.) is useful in designing photocatalysts that can operate efficiently under visible light irradiation. Also, an ICB method with a low acceleration energy is useful in preparing transparent TiO₂ thin films on various types of substrates for the efficient photocatalytic degradation of pollutants diluted in water and air. The combination of the ICB method and metal ion implantation can develop the TiO₂ thin films that are able to operate not only under UV light but also under visible light irradiation.     

口腔癌相关唾液肿瘤生物标志物的分析检测研究进展

口腔癌系头颈部癌，癌组织均位于口腔内，其非侵入性早期诊断是减少该病死亡的有效手段.唾液系口腔癌变相关物质首先释放进入的体液，取材方便，安全无创，是口腔癌普查筛选、早期诊断的首选指标.本文对唾液肿瘤生物标志物的种类、目前国内外常用的检测方法进行概述，重点阐述新型电化学生物传感方法在口腔癌相关唾液肿瘤生物标志物检测方面的相关应用及其最新研究进展.并对口腔癌相关唾液肿瘤生物标志物电化学传感技术的未来发展方向提出展望，拟为其深入研究与应用提供参考.     

微视频技术在基础化学实验教学中的实践应用

以高校基础化学实验"从海带中提取碘""三草酸合铁（Ⅲ）酸钾的制备"为例，分别探讨了微视频技术在化学基本操作实验和综合设计型实验中的具体应用；此外，举例说明利用Flash软件制作的虚拟微视频可以在仪器分析实验中清晰地再现仪器真实操作中的每一个步骤，弥补了学生在实验前无法实际操作仪器的不足。实践证明，微视频技术的应用，丰富了基础化学实验教学模式，增强了学生自主学习的能力和动手能力，提高了实验成功率和实验教学效果。