Oligonucleotide ligation assay-based DNA chip for multiplex detection of single nucleotide polymorphism

An oligonucleotide ligation assay-based DNA chip has been developed to detect single nucleotide polymorphism. Synthesized nonamers, complementary to the flanking sequences of the mutation sites in target DNA, were immobilized onto glass slides through disulfide bonds on their 5' terminus. Allele-specific pentamers annealed adjacent to the nonamers on the complementary target DNA, containing 5'-phosphate groups and biotin labeled 3'-ends, were mixed with the target DNA in tube. Ligation reactions between nonamers and pentamers were carried out on chips in the presence of T4 DNA ligase. Ligation products were directly visualized on chips through enzyme-linked assay. The effect of G:T mismatch at different positions of pentamers on the ligation were evaluated. The results showed that any mismatch between pentamer and the target DNA could lead to the decrease of ligation, which can be detected easily. The established approach was further used for multiplex detection of mutations in rpoB gene of rifampin-resistant Mycobacterium tuberculosis clinical isolates. (C) 2003 Elsevier B.V. All rights reserved.

H+ISFET-based biosensor for determination of penicillin G

A biosensor based on an H+ ion sensitive field effect transistor (H+-ISFET) and penicillin G acylase has been developed. The response time of the sensor to different concentrations of penicillin G was 30 s. In a 20 mM phosphate buffer at pH 7.0, the linear range of the calibration curve was from 0.5 to 8 mM. The coefficients of variation for three samples with 20 repeated measurements were below 5%. Stability of the sensor could reach about 6 months and more than 1000 runs were performed without a significant decrease of the output value. The sensor was tested for measurement of the penicillin G content in penicillin fermentation broth. Forty samples with low and high concentrations of penicillin G were chosen for the correlation test. The values assayed by the sensor method were compared with the values assayed by HPLC method, the correlation coefficient (r) was 0.9944 and the regression equation was y = 1.034X - 2083.7 respectively. The different measuring methods are discussed in the text. (C) 1998 Published by Elsevier Science S.A. All rights reserved.

Liquid-filled microstructured polymer fibers as monolithic liquid-core array fibers

Liquid-filled microstructured polymer optical fibers (MPOFs) as monolithic liquid-core array fiber are proposed and prepared by injecting high-refractive-index liquid into the holes array of the MPOFs. One example for potential applications is demonstrated as a new kind of coherent imaging fiber. It provides great potential for applications in chemical sensing, biosensors, and endoscopy, particularly in bifunctional detection. (C) 2009 Optical Society of America

新型溶胶-凝胶电化学生物传感器的制备

发展电化学生物传感器是化学传感器研究的一个重要领域，也是人们一直感兴趣的一个研究方向。而且人们一直在探求，在生物传感器的制备过程中将生物活性分子和电子媒介体有效地固定于电极基质材料中的新型固定化方法。溶胶-凝胶材料所具有的诸多特性，如可低温包埋、孔径可控性、不溶胀性、化学惰性、物理刚性、光透性、易于制备以及良好的生物相容性，赋予了溶胶-凝胶过程有效地固定化各种敏感试剂的能力，基于溶胶-凝胶技术的各种传感器也随之蓬勃发展起来。在本论文的工作中，主要是通过利用新型溶胶-凝胶复合材料以及将溶胶-凝胶技术与其它固定化技术相结合，来制备各种新型电化学生物传感器。主要内容如下：1．首次将HRP和聚毗咯共同电沉积到二茂铁梭酸修饰的碳陶瓷电极表面，制备了过氧化氢生物传感器。实验结果表明，这种将表面修饰和碳陶瓷电极相结合的方法，能够有效地应用于各种生物传感器的制备。而且这种方法也为异相双酶生物传感器的制备提供了可能性。2．将含有葡萄糖氧化酶的聚毗咯薄膜修饰到含有HRP和媒介体的碳陶瓷电极表面，发展了一种新型双酶安培检测葡萄糖传感器。在这种传感器的异相双层结构中，各种酶均保持了良好的生物活性，而且所得传感器也具有良好的抗干扰能力以及对底物检测的高灵敏度。这种方法有望于将各种H_2O_2生成酶与HRP相结合，制备具有高选择性的其它生物传感器。3．以铱超微粉为导电介质，将其与溶胶-凝胶过程相结合，首次制备了新型铱陶瓷电极。溶胶一凝胶铱复合材料表现出了良好的催化活性，过氧化氢既可以在铱陶瓷电极上被电化学氧化，也可以在低电位下被电化学还原。并利用溶胶一凝胶铱复合材料进一步制备了第一代铱陶瓷葡萄糖生物传感器。由于H_2O_2检测过程中所需要的低工作电位，使得铱陶瓷酶电极具有对底物的高度选择性。4．利用双相还原法制备并表征了铱纳米粒子，并将纳米技术、自组装技术以及溶胶-凝胶技术相结合，制备了溶胶-凝胶铱复合电极。实验结果表明，琉基功能化烷氧基硅烷能够组装到金电极表面形成凝胶薄膜修饰电极，通过铱纳米粒子与凝胶薄膜中自由疏基间的吸附作用，铱纳米粒子能够被容易地固定到凝胶薄膜中。所制备的铱陶瓷电极同样表现出了对H_2O_2高度的灵敏度以及选择性。5．利用二氧化硅凝胶的自组装技术构建了甲苯胺蓝修饰电极，并用于电化学催化氧化NADH的测定。实验中，详细探讨了甲苯胺蓝在凝胶组装修饰电极中的电化学行为。结果表明，此类修饰电极的双层结构有效地防止了催化剂的渗漏以及NADH检测过程中由于吸附作用而造成的电极污染问题。

新型安培生物传感器的研制

由于生物传感器在临床、环境、食品等领域具有广阔的应用前景，近年来发展迅速。本论文从合成新型溶胶-凝胶衍生的生物相容性固定化载体和在碳基底表面构筑有序的低聚苯胺分子线两方面对安培酶电极进行了研究。主要结果如下：1．利用溶胶-凝胶／水凝胶复合材料作为载体固定辣根过氧化物酶，构造了无试剂、高稳定的过氧化氢生物传感器。该传感器有望应用于实际在线检测过氧化氢。2．合成了新型功能化溶胶-凝胶／EastmanAQ聚合物复合材料，成功地固定了带正电荷的媒介体，构造了一种响应快速，灵敏度高的无试剂过氧化氢传感器。该功能化复合材料可应用于其它分析检测中。3．合成了钛溶胶-凝胶／聚乙烯醇接枝4-乙烯吡啶复合材料。以该材料为基础制备的酪氨酸生物传感器和葡萄糖生物传感器均表现出高灵敏度，好长期稳定性等优点。该复合材料可应用于其它生物分子的固定。4，合成了有机修饰的溶胶-凝胶／壳聚糖复合材料。由于该材料生物相容性好且价格低廉，因此以其为固定化载体制备的葡萄糖生物传感器有望实现商品化。5．利用电化学还原重氮盐法在碳电极表面构筑了有序的低聚苯胺分子线。利用循环伏安法、X-射线光电子能谱法、扫描隧道显微镜法进行了表征。该设计在传感器、诊断及分子电子领域具有潜在应用前景。

Detection of avian influenza virus subtype H5 using a biosensor based on imaging ellipsometry

A novel method is reported for the detection of avian influenza virus subtype H5 using a biosensor based on high spatial resolution imaging ellipsometry (IE). Monoclonal antibodies specific to H5 hemagglutinin protein were immobilized on silicon wafers and used to capture virus particles. Resultant changes on the surface of the wafers were visualized directly in gray-scale on an imaging ellipsometry image. This preliminary study has shown that the assay is rapid and specific for the identification of avian influenza virus subtype H5. Compared with lateral-flow immunoassays, this biosensor not only has better sensitivity, but can also simultaneously perform multiplexed tests. These results suggest that this biosensor might be a valuable diagnostic toot for avian influenza virus detection. (c) 2009 Elsevier B.V. All rights reserved.

Determination of urinary oxidative DNA damage marker 8-hydroxy-2 '-deoxyguanosine and the association with cigarette smoking

8-hydroxy-2'-deoxyguanosine (8OHdG) has been widely used as a biomarker of oxidative DNA damage in both animal models and human studies. To evaluate the effect of cigarette smoking on oxidative stress, we studied the levels of urinary 8OHdG from smokers and non-smokers and investigated the association with cigarette smoking. The urinary 8OHdG concentrations were determinated by capillary electrophoresis with end-column amprometric detection (CE-AD) after a single-step solid phase extraction (SPE), and then quantitatively expressed as a function of creatinine excretion. To increase the concentration sensitivity, a dynamic pH junction was used and the focusing effect was obvious when using 30 mM phosphate (pH 6.50) as sample matrix. The limit of detection is 4.3 nM (signal-to-noise ratio S/N = 3). The relative standard deviation (R.S.D.) was 1.1% for peak current, and 2.3% for migration time. Based on the selected CE-AD method, it was found that the mean value of urinary 8OHdG levels in the smokers significantly higher than that in non-smokers (31.4 +/- 18.9 nM versus 14.4 +/- 7.6 nM, P = 0.0004; 23.5 +/- 21.3 mug g(-1) creatinine versus 12.6 +/- 13.2 mug g(-1) creatinine, P = 0.028). (C) 2004 Elsevier B.V. All rights reserved.

Study of urinary 8-hydroxydeoxyguanosine as a biomarker of oxidative DNA damage in diabetic nephropathy patients

Increased oxidative stress induced by hyperglycemia may contribute to the pathogenesis of diabetic complications. Urinary 8-hydroxydeoxyguanosine (8-OHdG) has been reported to serve as a sensitive biomarker of oxidative DNA damage and also of oxidative stress. This article studied oxidative DNA damage in patients with diabetic nephropathy and in healthy control subjects by urinary 8-OHdG evaluations. Contents of 8-OHdG in urine were analyzed by capillary electrophoresis with end-column amperometric detection (CE-AD) after a single-step solid-phase extraction (SPE). Levels of urinary 8-OHdG in diabetic nephropathy patients with macroalbuminuria was significant higher than in control subjects (5.72 +/- 6.89 mumol/mol creatinine versus 2.33 +/- 2.83 mumol/mol creatinine, P = 0.018). A significant difference of 24 h urinary 8-OHdG excretions exists between the patients with macroalbuminuria and the patients with nonnoalbuminuria (19.2 +/- 16.8 mug/24 h versus 8.1 +/- 1.7 mug/24 h, P = 0.015). There was a positive correlation between urinary excretion of 8-OHdG and glycosylated hemoglobin (HbA(1)c) (r = 0.287, P = 0.022). A weak correlation exists between the levels of 8-OHdG and triglyceride (r = 0.230, P = 0.074). However, the urinary 8-OHdG contents are not correlated with blood pressure and total cholesterol. The increased excretion of urinary 8-OHdG is seen as indicating an increased systemic level of oxidative DNA damage in diabetic nephropathy patients. (C) 2004 Elsevier B.V. All rights reserved.

Potentiometric glucose sensors

The determination of glucose is possible with the enzymatic reaction of glucose oxidase and potentiometric detection. The signal is proportional to the concentration up to 50 mg/dl. This value is fixed by the concentration of oxygen in the sample. By adding catalase, concentrations up to 2000 mg/dl are detectable. The steepness of the calibration curve is not affected by oxygen concentrations greater than 4 mg/l. In contrast to amperometric sensors, an influence of deposits on the electrodes surface on the signal cannot be found with potentiometric sensors

Amplified electrochemical aptasensor taking AuNPs based sandwich sensing platform as a model

Here, we report a sensitive amplified electrochemical impedimetric aptasensor for thrombin, a kind of serine protease that plays important role in thrombosis and haemostasis. For improving detection sensitivity, a sandwich sensing platform is fabricated, in which the thiolated aptamers are firstly immobilized on a gold substrate to capture the thrombin molecules, and then the aptamer functionalized Au nanoparticles (AuNPs) are used to amplify the impedimetric signals.

A biofuel cell with enhanced performance by multilayer biocatalyst immobilized on highly ordered macroporous electrode

A one-compartment glucose/O-2. biofuel cell based on an electrostatic layer-by-layer (LbL) technique on three-dimensional ordered macroporous (3DOM) gold electrode was described. A 3DOM gold electrode was synthesized electrochemically by an inverted colloidal crystal template technique. Then the macroporous gold electrodes were functionalized with Au nanoparticles (AuNPs) and enzyme, glucose dehydrogenase (GDH) or laccase.

A sensitive NADH and glucose biosensor tuned by visible light based on thionine bridged carbon nanotubes and gold nanoparticles multilayer

A NADH and glucose biosensor based on thionine cross-linked multiwalled carbon nanotubes (MWNTs) and Au nanoparticles (Au NPs) multilayer functionalized indium-doped tin oxide (ITO) electrode were presented in this paper. The effect of light irradiation on the enhancement of bioelectrocatalytic processes of the biocatalytic systems by the photovoltaic effect was investigated.

Electrochemical characteristics of mediated laccase-catalysis and electrochemical detection of environmental pollutants

Laccase has been immobilized on the carbon nanotubes modified glassy carbon electrode surface by adsorption. As-prepared laccase retains good electrocatalytic activity to oxygen reduction by using 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) as the mediator. It can be used as a biosensor for the determination of catechol with broad linear range.

Utilizing a CdTe quantum dots-enzyme hybrid system for the determination of both phenolic compounds and hydrogen peroxide

In this paper, we attempt to construct a simple and sensitive detection method for both phenolic compounds and hydrogen peroxide, with the successful combination of the unique property of quantum dots and the specificity of enzymatic reactions. In the presence Of H2O2 and horseradish peroxidase, phenolic compounds can quench quantum dots' photoluminescence efficiently, and the extent of quenching is severalfold to more than 100-fold increase. Quinone intermediates produced from the enzymatic catalyzed oxidation of phenolic compounds were believed to play the main role in the photoluminescence quenching.