硫堇与DNA分子相互作用的电化学方法研究

采用交流阻抗技术和循环伏安法 ,研究了在硫堇自组装膜修饰金电极上 ,以及在硫堇或DNA吸附修饰的玻碳电极上 ,硫堇与DNA分子的相互作用;硫堇自组装膜修饰金电极与DNA分子作用后 ,阻抗增大 ,表明它们之间发生了作用 ;吸附在玻碳电极上的硫堇 (DNA)与DNA(硫堇 )作用后 ,峰电位和峰电流均发生了变化 ,结合光谱测定结果 ,表明硫堇与DNA分子间存在着嵌插、静电等作用 ,二者作用的反应速度与分子在电极上固定的位置有关;在PBS缓冲液中硫堇 -DNA的表观结合常数为4.9×104L·mol -1 ;交流阻抗技术和循环伏安法是研究小分子与DNA分子间相互作用的经济、快速、简便的方法     

溶胶-凝胶法修饰的一次性氯离子选择性电极的研究

溶胶-凝胶法(sol-gel)对固定试剂的种类和数量具有可调性,又具有保持性能稳定的潜在优势;一些小分子离子可以自由进出sol-gel的孔径,使得sol-gel基质内外浓度相等,因而可制备化学电极。本文通过正硅酸乙酯[TEOS]在适宜的酸催化下,水解制得电极材料,采用溶胶．凝胶掺杂技术,成功地修饰了新型氯离子选择性电极,这种电极的线性范围和AgCl-AgS2固态膜电极、     

基于纳米自组装技术的功能化溶胶-凝胶过氧化氢生物传感器

结合功能化溶胶-凝胶(sol-gel)网络结构、自组装技术和纳米粒子效应,提出一种生物传感界面构建方法.利用自组装技术在玻碳电极表面组装氨基化sol-gel膜,通过与自组装膜间的强烈作用将纳米金粒子固定于sol-gel网络中,再通过静电吸附作用实现辣根过氧化物酶(HRP)在纳米金粒子表面的固定化,构建纳米自组装HRP传感界面.将制备的传感器用于对H2O2的催化还原,很好地保持了酶的生物活性,改善了传感器的灵敏度.     

超薄硅溶胶-凝胶修饰膜的制备与表征

报道了一种制备硅溶胶－凝胶膜（sol-gel)的新方法。通过对形成溶胶和凝胶化过程的控制，获得了制备超薄溶胶－凝胶膜的最佳条件，并对膜的性质进行了一系列表征。实验表明，所得溶胶－凝胶膜具有良好的结构特征。采用光度法、电化学方法可有效地对膜的厚度进行表征。     

硅溶胶-凝胶包埋纳米金和酶的葡萄糖生物传感器

采用溶胶-凝胶技术将金纳米粒子和葡萄糖氧化酶一次性固定于硅溶胶-凝胶的网络结构中,制备了葡萄糖生物电化学传感器并优化了传感器的制备条件。酶电极对葡萄糖具有良好的电化学响应,葡萄糖浓度在0.02~2.0 mmol/L范围内和催化电流呈线性关系,检出限为0.005 mmol/L。酶电极在4 ℃下贮存100 d后对葡萄糖的响应仅下降8%。该酶电极灵敏度高、响应快、稳定性好。     

聚亚甲基蓝和纳米金修饰玻碳电极的葡萄糖生物传感器

用循环伏安法在玻碳电极上电聚合一层稳定的亚甲蓝聚合物膜,研究了这层膜在0.1mol/L磷酸缓冲溶液(pH7.0)中的电化学性质。用纳米金溶胶与聚乙烯醇缩丁醛(PVB)构成复合固酶基质,采用溶胶-凝胶法固定葡萄糖氧化酶(GOD)于亚甲蓝修饰的玻碳电极表面,制成了新型葡萄糖生物传感器。实验发现,加入纳米金后提高了酶电极对葡萄糖的电流响应,所制备的传感器具有响应快、灵敏度高、稳定性好,对葡萄糖的线性响应范围为1×10-6~3×10-3mol/L,检出限为5×10-7mol/L。并具有抗尿酸、抗坏血酸干扰的特点。     

基于纳米金与碳纳米管-纳米铂-壳聚糖纳米复合物固定癌胚抗原免疫传感器的研究

采用纳米金(nano-Au)、多壁碳纳米管-纳米铂-壳聚糖的纳米复合物(MWNT-Pt-CS)及电子媒介体硫堇(Th)固载抗体制得高灵敏癌胚抗原免疫传感器．首先, 于壳聚糖溶液中用NaBH4还原H2PtCl6, 并将多壁碳纳米管分散于其中制得碳纳米管-纳米铂-壳聚糖纳米复合物, 并将其滴涂在玻碳电极上成膜; 然后, 吸附电子媒介体硫堇制得硫堇/碳纳米管-纳米铂-壳聚糖(Th/MWNT-Pt-CS)修饰电极．利用壳聚糖和硫堇分子中大量的氨基固定纳米金并吸附癌胚抗体(anti-CEA); 最后, 用辣根过氧化物酶(HRP)封闭活性位点从而制得高灵敏电流型免疫传感器．在优化的实验条件下, 该传感器响应的峰电流值与癌胚抗原(carcinoembryonic antigen)浓度在0.5～10和10～120 ng/mL的范围内保持良好的线性关系, 检测限为0.2 ng/mL．     

纳米TiO2膜电极的电化学阻抗谱

纳米TiO2膜电极的电化学阻抗谱;纳米TiO2膜;电化学阻抗谱;催化电极;异相氧化还原电对     

聚硫堇修饰微带金电极的性质及对NADH的催化氧化

报道了硫堇在微带金电极上的电化学聚合过程，用红外光谱对聚硫堇进行了表征；研究了聚硫堇的电化学性质，发现聚硫堇在＋０．５～－０．７Ｖ（ｖｓ．ＳＣＥ）电位范围内有两对氧化还原峰，峰电位分别为：Ｅ＝－０．０３Ｖ、Ｅ＝０．０５Ｖ，Ｅ＝－０．２４Ｖ、Ｅ＝－０．１７Ｖ（ｖｓ．ＳＣＥ）。它们的式量电位Ｅ~（ｏ＇）随ｐＨ而变化，在弱酸性溶液中，Ｅ~（ｏ＇）／ｐＨ为－２９ｍＶ／ｐＨ（２５℃）；而在弱碱性溶液中则为－５６ｍＶ／ｐＨ。聚硫堇修饰微带金电极对ＮＡＤＨ的氧化具有催化作用，文中对电催化过程进行了探讨。     

CeO2—TiO2复合纳米晶多孔膜的光电化学行为

用溶胶凝胶法制备了CeO2－TiO2复合纳米晶多孔膜电极，并用XRD及原子力显微镜（AFM）进行表征．通过光电化学研究，发现了CeO2-TiO2复合纳米晶电极光响应的p型和n型转换现象．结果表明，随着CeO2含量的不同及外电场的变化，CeO2－TiO2复合纳米晶电极可以呈现不同的光响应．     

Study of the Nano-Size Silica Sol–Gel Film as the Matrix of Chemically Modified Electrode

This paper reports a new method to make the sol–gel film from silicate. It provided more profitable conditions than hydrolysis of alkoxyl silane to prepare the high-quality nanometers thin film. The thin film could be applied as the matrix to directly modify the molecules of methylene blue on electrode surface and kept their electrochemical activity excellently. It exhibited the remarkable catalytic activity for the oxidation of NADH or reduction of hemoglobin while severally embedding them in the sol–gel film together with methylene blue.     

Preparation,Electrochemistry, and Electrocatalytic Activity of Lead Pentacyanonitrosylferrate Film Immobilized on Carbon Ceramic Electrode

Lead pentacyanonitrosylferrate (PbPCNF), a new Prussian blue analog, was immobilized on the surface of a carbon ceramic electrode (CCE) prepared by sol‐gel method. The immobilization process consists of adding a certain amount of metallic lead to the electrode matrix before gelation, and chemical derivatization of Pb on the electrode surface to a PbPCNF solid film by immersing the electrode in a solution of sodium pentacyanonitrosylferrate (PCNF). The composition of the synthesized PbPCNF was characterized by FTIR, scanning electron microscopy (SEM), and energy‐dispersive X‐ray (EDX) techniques. The resulting modified electrode showed electroactivity at two redox centers. The electrochemical behavior of the PbPCNF modified carbon ceramic electrode (PbPCNF|CCE) was studied by cyclic voltammetry. Under optimized conditions the peak‐to‐peak separation is only 39 mV, indicative of a surface reaction. Ion effects of the supporting electrolyte suggest that cations have a considerable effect on the electrochemical behavior of the modified electrode. The transfer coefficient (α) and the charge transfer rate constant at the modifying film|electrode interface (k_s) were calculated. The electrocatalytic activity of the modified electrode toward the electro‐reduction of peroxodisulfate was studied in details.     

基于溶胶-凝胶技术的磷钨杂多酸化学修饰电极的组装及其电催化

将 Dawson型磷钨杂多酸盐 K6 P2 W1 8O6 2 · 1 0 H2 O( P2 W1 8)掺杂到溶胶 -凝胶中 ,滴涂在碳糊电极表面 ,制备成化学修饰电极 .并对该化学修饰电极的电化学行为 ,包括溶液 p H值的影响和电极稳定性等进行了详细的研究 .结果表明 ,此电极既保持了该杂多酸的电化学活性和电催化性能 ,又具有良好的稳定性和灵敏度 .实验发现 ,在 0 .5mol/L H2 SO4溶液中 ,掺杂在溶胶 -凝胶膜中的 P2 W1 8的第 3、第 4个还原峰对 NO- 2 离子具有很好的电催化活性 ,且催化电流同 NO- 2 浓度呈线性关系 .同时 ,P2 W1 8的第 3、第 4个还原峰对分子氧也具有很好的电催化活性 .     

Direct Electrochemistry of Cytochrome c on a Silica Sol‐Gel Film Modified Electrode

Dilute silica sol‐gel was simply dropped on the surface of a basal plane graphite electrode (BPGE) to form a silica sol‐gel film modified electrode. Direct electrochemical response of cytochrome c (Cyt c) on the modified electrode was observed by cyclic voltammetry (CV). The results suggested that Cyt c could be tightly adsorbed on the surface of the silica sol‐gel film modified electrode. A couple of well‐defined and nearly reversible redox peaks can be observed in a phosphate buffer solution (pH 7.0), which anodic and cathodic peak potentials were at ?0.243 and ?0.306 V (vs. Ag/AgCl), respectively. Cyt c adsorbed on the surface of silica sol‐gel film shows a remarkable electrocatalytic activity for the reduction of oxygen. Based on these, a third‐generation biosensor could be constructed to detect the concentration of oxygen in aqueous solution.     

A Novel Photo‐Induced Electrochemical Biosensing Method Based on Fluorescent Labeled Molecular Beacon

A novel photo‐induced electrochemical biosensing method has been developed based on fluorescence quenching effect and electrochemical method. In this sensing strategy, the molecular beacon probes labeled with methylene blue were immobilized on the gold nanoparticles modified gold electrode surface firstly; then dopamine was assembled on the electrode surface through electrostatic interaction with gold nanoparticles. Under the continuous illumination, the fluorescence of the methylene blue was quenched by the gold nanoparticles before hybridization; after hybridization with the complementary DNA, methylene blue was far away from the gold nanoparticles and the fluorescence recovered, and then singlet oxygen was generated in the photosensitive reaction of methylene blue in the presence of dissolved oxygen. Singlet oxygen reacted with dopamine, which resulted in the reduction of concentration of the dopamine on the electrode surface. The current of the dopamine on the electrode was used for the sensing of the conformational change of molecular beacon and hence for the detection of target DNA.     

Preparation of GOD/Sol‐Gel Silica Film on Prussian Blue Modified Electrode for Glucose Biosensor Application

A novel amperometric glucose biosensor was fabricated by in situ incorporating glucose oxidase (GOD) within the sol‐gel silica film on a Prussian blue (PB) modified electrode. The method is simple and controllable, which combined the merits of in situ immobilizing biomolecules in sol‐gel silica film by electrochemical method and the synergic catalysis effects of PB and GOD molecules. Scanning electron microscopy (SEM) showed that the GOD/sol‐gel silica film was homogeneous with a large number of three‐dimensional nanopores, which not only enhanced mass transport, but also maintained the active configuration of the enzyme molecule and prevented the leakage of enzyme, therefore improved the stability and sensitivity of the biosensor. The fabricated biosensor showed fast response time (10 s), high sensitivity (26.6 mA cm^?2 M^?1), long‐term stability, good suppression of interference, and linear range of 0.01 mM–5.8 mM with a low detection limit of 0.94 μM for the detection of glucose. In addition, the biosensor was successfully applied to determine glucose in human serum samples.     

A bifunctional electrochemical aptasensor based on AuNPs-coated ERGO nanosheets for sensitive detection of adenosine and thrombin

A simple and sensitive bifunctional electrochemical aptasensor for detection of adenosine and thrombin has been developed using gold nanoparticles–electrochemically reduced graphene oxide (AuNPs-ERGO) composite film-modified electrode. Firstly, the reduced graphene oxide film and AuNPs were sequentially immobilized on glassy carbon electrode (GCE) surface. Secondly, thrombin aptamer was immobilized on the modified electrode. Finally, adenosine aptamer was hybridized with it to serve as a recognition element and methylene blue (MB) as electrochemical signal indicator. In the presence of adenosine or thrombin, the sensor recognized it and a conformational change was induced in aptamer, resulting in decrease of the peak current of MB. The linear relation between concentration of adenosine or thrombin and peak current of MB allowed quantification of them. Thanks to the special electronic characteristic of AuNPs-ERGO composite film, sensitivity of sensor was greatly improved. Under optimal conditions, the proposed aptasensor presented an excellent performance in a linear range of 25 nM to 750 nM for adenosine and 0.5 nM to 10 nM for thrombin. Detection limits were estimated to be 8.3 nM for adenosine and 0.17 nM for thrombin, respectively. Moreover, dual-analyte detection of adenosine and thrombin was achieved without potentially increasing the complexity and cost of the assay.

     

基于聚苯胺掺杂乙醇胺固定DNA电化学传感器的研究

本研究以电化学聚合法制备了聚苯胺掺杂乙醇胺修饰电极,并成功固定了DNA探针。文中对修饰电极的制备和DNA的固定杂交条件进行了探讨,并利用循环伏安法测定嵌入双链DNA(dsDNA)分子碱基对中的亚甲基蓝的氧化还原峰电流,识别和测定溶液中互补的单链DNA(ssDNA)片段,从而实现对溶液中不同基因片段的检测。     

基于聚亚甲基蓝-碳纳米管复合膜固载血红蛋白的H2O2生物传感器

采用吸附和电化学聚合修饰方法,制得了聚亚甲基蓝-碳纳米管聚合膜玻碳电极(PMB-MWNTs/GCE),再将血红蛋白(Hb)固定在PMB-MwNTs/GCE表面,制备了稳定的Hb/PMB-MwNTs//GCE的H2O2生物传感器,并用循环伏安法对修饰电极的生物电催化行为进行了表征.研究结果表明,固定在PMB-MWNTs/...     

Evaluation of Meldola Blue‐Carbon Nanotube‐Sol‐Gel Composite for Electrochemical NADH Sensors and Their Application for Lactate Dehydrogenase‐Based Biosensors

A novel MB‐SWNT‐sol‐gel nanocomposite material was prepared by the sol‐gel process incorporating a redox mediator and carbon nanotubes. The electrocatalytic properties of the nanomaterial based sensor toward NADH oxidation were studied by electrochemical measurements. Significant enhancement of oxidation current is obtained at electrodes modified by MB‐SWNT‐sol‐gel in comparison with the analogous carbon black and/or graphite composite modified electrode. The usefulness of the nanocomposite material as a matrix for immobilizing enzymes is also demonstrated. Analytical parameters of D ‐lactate biosensors with and without SWNT in the hybrid film were compared demonstrating that performance of the biosensor was significantly improved when introducing SWNT.