基于纳米金胶标记DNA探针的电化学DNA传感器研究

以纳米金胶为标记物,将其标记于人工合成的5-端巯基修饰的寡聚核苷酸片段上,制成了具有电化学活性的金胶标记DNA电化学探针;在一定条件下,使其与固定在玻碳电极表面的靶序列进行杂交反应,利用ssDNA与其互补链杂交的高度序列选择性和极强的分子识别能力,以及纳米金胶的电化学活性,实现对特定序列DNA片段的电化学检测以及对DNA碱基突变的识别.     

基于硫化镉纳米团簇标记DNA电化学传感的研究

合成了表面具有自由羧基的硫化镉纳米团簇，以乙基-（3-二甲基丙基）碳二 亚胺盐酸盐为偶联活化剂，将其标记于人工合成的5'端氨基修饰的寡聚核苷酸片段 上，制备成CdS纳米团簇标记DNA探针，该寡聚核苷酸片段与大肠杆菌肠毒素基因相 关。在一定的条件下，使基与固定晨玻碳电极表面的待测DNA序列进行杂交反应， 利用阳极溶出示差脉冲伏安法（ASDPV）间接测定Cd的量，实现对互补、非互补 DNA片段的识别和电化学检测，从而对大肠杆菌肠毒素基因片段识别和检测。     

二茂铁标记DNA电化学探针的研制及性质研究

以乙基－（3－二甲基丙基）碳化二亚胺盐酸(EDC)为偶联活化剂,利用缩合反应分别将电化学活性物质氨基二茂铁（Aminoferrocene,AFC)和苯基二茂铁（Ferrocencearboxadehyde,FCA)成功地标记在变性小牛胸腺DNBA片段上,制备成二茂铁标记DNA探针,分别采用电化学,紫外,红外光谱等方法研究了二茂铁标记DAN探针的性质,计算了二茂铁的标记效率,变性小牛胸腺DNA的反应效率以及二茂铁化合物与变性小牛胸腺DNA的反应比率,实验表明,氨基二茂铁和醛基二茂铁与DNA上的磷酸基是以1：1比率进行的反应,该标记反应不影响DNA链碱基的紫外吸收,二茂铁标记DNA探针在石墨电极上有良好的电化学影响,将制备好的二茂铁标记DNA电化学探置于冰箱中冷冻（温度低于－15度）保存3个月后用于测定,峰电流仅下降1．2％。     

电化学DNA生物传感器定量检测根癌农杆菌终止子基因片段

通过自组装法及共价法固定单链脱氧核糖核酸(ssDNA),制备了电化学DNA生物传感器。将巯基丙酸(MPA)自组装于金电极表面形成单分子膜,再利用1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDC)和N-羟基琥珀酰亚胺(NHS)的活化作用将ssDNA探针序列固定于金电极表面。将ssDNA修饰的电极与待测溶液中人工合成的转基因食品中常有的根癌农杆菌终止子(NOS)基因片段进行杂交,在[Fe(CN)6]3-/4-溶液中进行循环伏安和电化学阻抗谱扫描,表征ssDNA固定及杂交过程。优化了ssDNA固定条件。待测溶液中DNA浓度在1.0×10-7～1.0×10-10mol/L范围时,其浓度的对数值和ssDNA/Au电极与dsDNA/Au电极峰电流差值的变化值呈线性相关关系,相关系数为0.9822,检出限为8.1×10-11mol/L。     

纳米探针芯片技术用于微量乙肝病毒DNA的检测

利用两组探针修饰的微粒:(1)表面标记有可与待测乙肝病毒(HBV) DNA另一端结合的纳米金探针1(信号探针)以及可与信号探针部分结合的纳米金探针2(检测探针);(2)表面标记有可与待测HBV DNA一端结合的磁珠探针(捕捉探针1).检测靶HBV DNA时,磁珠探针与信号探针在液相中可分别与HBV DNA靶序列一端结合最终形成三明治样结构.再以磁场将三明治样复合物从反应液中分离,以DTT溶液将信号探针从纳米金颗粒上洗脱.洗脱后的信号探针数量反映靶基因的多寡,信号探针一段与预先点样的基因芯片上的捕捉探针2结合,检测探针与信号探针另一段相结合,最后用银染液将检测探针显色从而得到靶目标DNA相对定量信息.结果表明,本检测方法的检测灵敏度达到10-15 mol/L水平.检测时间少于1.5 h,检测结果与HBV DNA水平呈现较好的线性关系且无假阳性结果;本方法有望用于乙肝病人血清中HBV DNA的快速筛测及其它微生物基因的检测.     

基于纳米ZnO/壳聚糖复合膜DNA电化学传感器用于HIV基因的免标记检测

以室温固相合成法制备纳米ZnO,通过壳聚糖(CHIT)的成膜效应将纳米ZnO固定在玻碳电极(GCE)表面,制得的ZnO/CHIT/GCE电极成为DNA固定和杂交的良好平台。DNA的固定和杂交通过电化学交流阻抗进行表征。以电化学交流阻抗免标记法检测目标DNA,固定于电极表面的DNA探针与目标DNA杂交后使电极表面的电子传递电阻增大,以此作为检测信号可以高灵敏度地测定目标DNA。电化学阻抗谱检测人类免疫缺陷病毒(HIV)基因片段的线性范围为2.0×10-11~2.0×10-6mol/L,检出限为2.0×10-12mol/L。     

DNA电化学传感器在DNA损伤研究中的应用

利用单链DNA分子共价固定在石墨电极表面,采用核酸分子杂交技术,以道诺霉素作为杂交指示剂形成DNA电化学传感器.研究了在不同致突变剂的作用下,特定碱基序列的DNA在电极表面能否杂交及杂交程度的差异,探讨了DNA突变情况及可能的突变机理.     

SERS标记的金纳米棒探针用于免疫检测

报道了基于金纳米棒表面增强拉曼散射(SERS)的免疫检测. 将拉曼活性分子对巯基苯甲酸吸附于金纳米棒表面, 制备出SERS标记的金纳米棒探针. 该探针和蛋白抗体结合形成SERS标记抗体. 通过SERS标记抗体、待测抗原和俘获抗体(固体基底上修饰的抗体, 即俘获抗体)之间的免疫应答反应, 将金纳米棒探针组装到固体基底上, 形成SERS标记抗体-抗原-俘获抗体 “三明治”夹心复合体. 待测抗原浓度越大, 固体基底上俘获的金纳米棒探针的数目越多, 从而可通过SERS信号的强弱来检测待测抗原的浓度. 由于金纳米棒的表面等离子体共振(SPR)峰位置可以在较宽的范围内调控, 可通过激发光和SPR的耦合来提高SERS信号, 从而提高免疫检测的灵敏度. 单组分抗原可检出的浓度范围高于1×10－8 mg/mL.     

电化学石英晶体微天平实时表征和定量检测短序列DNA

利用电化学石英晶体微天平(EQCM)这一灵敏的质量和电化学传感器测定特定序列DNA。应用自组装膜技术在压电石英晶振表面自组装一带羧基的α－硫辛酸单层膜,通过盐酸1-乙基-3-(3-二甲基氨基丙基)碳二亚胺(EDC)及N-羟基琥珀酰亚胺(NHS)共价固化寡聚核苷酸为探针,用于测定与其碱基序列互补的DNA。实验中EQCM实时监测了α-硫辛酸的自组装过程、探针固化过程及其与cDNA杂交过程。定量得出了探针固化量及cDNA杂交量。在酸性、中性和碱性条件下,分别对固化和杂交过程进行表征,实验发现探针固化及DNA杂交都受pH影响,本文对此现象进行了解释。同时,利用染料Hoechst33258的电化学活性,使其与双链DNA嵌合,通过测量Hoechst33258的电化学信息进一步验证了DNA杂交关键步骤。     

电化学发光和电化学生物传感器的研究

本研究小组近年来在电化学发光DNA和适体传感器研究和无标记以及阵列电化学DNA和适体传感器方面进行了一些工作,重点介绍如何提高生物传感器灵敏度进行传感界面设计的一些思路.利用纳米粒子提高灵敏度和再现性的途径主要有三种,一是用纳米材料修饰电极上,提高待测物或探针在电极表面的固定量;二是用纳米材料作为信号分子的载体或信号粒子, 以提高检测信号的强度~([1]);三是纳米材料直接作为信号物质~([2]).     

Electrodeposition of manganese dioxide: effect of quaternary amines

The effect of quaternary ammonium salts (tetraethyl ammonium bromide, tetrapropyl ammonium bromide, and tetrabutyl ammonium bromide) on the structural, morphological, and electrochemical characteristics of electrolytic manganese dioxide (EMD) obtained from acidic aqueous sulfate solution has been investigated. Physical characterization of the EMD was achieved by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis, and Fourier transform infrared spectroscopy. The charge–discharge profile of the materials was determined to evaluate their potential for alkaline battery applications. The presence of these quaternary ammonium salts as organic additives in the solution increased the current efficiency while decreasing energy consumption during electrochemical deposition of manganese dioxide (MnO₂). All the additives influenced the discharge characteristics of the EMD samples significantly, producing a cathode material with increased cumulative discharge capacity relative to EMD prepared in the absence of additives. This is attributed to the ability of the additives to affect the particle size and morphology, and therefore electrochemical activity, of electrodeposited materials; the effects in the case of the additives investigated in this work were positive, producing a material with potential application to battery technology.     

味觉电化学传感器的研究——Ⅰ.甜、酸、苦、咸物质对模拟生物膜电位振动频率的影响

本文以十六烷基三甲基溴化铵/含苦味酸的硝基苯/蔗糖溶液为研究体系,发现甜、酸、苦、咸物质均能使体系的振动波形和频率发生变化,初步建立了测定有味物质的定性、定量方法,并对该味觉电化学传感器的响应机理进行了探讨。     

Electrochemically Activated Reaction of Benzoyl Halides with Carbon Dioxide

The electrochemical activation and carboxylation of benzoyl halides (benzoyl bromide, chloride, and fluoride) were studied. It was found that the yield of phenylglyoxylic acid increases from zero to 88% in the transition from benzoyl fluoride to the chloride and bromide. The effect of the nature of the halogen atom in the benzoyl halide and also the nature of the supporting electrolyte and the electrode material on the electrochemical reduction and carboxylation of benzoyl halides was studied.     

由抑制剂引起的高反差机理研究

本文利用吸附曲线及电化学的方法,研究了一系列抑制剂在银及溴化银上的吸附行为,将这些吸附性质与显影过程中相应的抑制剂存在时的显影结果对比,实验表明:只有当抑制剂在银上为中等的吸附,而在溴化银上吸附很小时,才可能利用抑制剂达到高反差。相应的机理及抑制剂在银上的吸附性质在文中也作了讨论。     

Spectroelectrochemistry study on the electrochemical reduction of ethidium bromide.

The electrochemical reduction mechanism of ethidium bromide was first studied by spectroelectrochemistry. This reduction was proved to be a two-step process by cyclic voltammetry, differential pulse voltammetry and spectroelectrochemistry, in which each step was proved to be a one-electron transfer process by a spectropotentiostatic fluorescence technique. Hydroethidine was confirmed to be the final product by comparing the spectrum of the product of the electrochemical reduction to that of the product of the chemical reduction of ethidium bromide, and a carbon-centered radical was concluded to be a reasonable intermediate product during the electrochemical reduction of ethidium bromide.     

Electrochemical behaviour of triphenylgermanium bromide

The electrochemical behaviour of triphenylgermanium bromide has been thoroughly investigated using various electrochemical techniques including polarography, cyclic voltammetry and controlled potential coulometry. It has been found that in non-aqueous solvents triphenylgermanium bromide gives only one small drawn-out wave, while in aqueous-organic media two reduction waves are observed. The first wave has been ascribed to adsorption of the products of the reduction step II. The triphenylgermanium free radicals have been postulated to combine rapidly with protons in acidic media or to abstract hydrogen from water in alkaline media. The protonated species has been found to be reduced at potentials at which normal reduction of triphenylgermanium bromide takes place giving rise to a superimposed catalytic proton-discharge wave. A mechanism of reduction of triphneylgermanium bromide at the DME has been postulated and analytical methods for the determination of triphenylgermanium compounds at the formulation and trace analysis levels have been developed.     

Fabrication and Characterization of a Thin-Layer Electrochemical Flow Cell and Its Application for Flow Analysis

The design and fabrication of a home-made thin-layer electrochemical flow cell are reported. The performance and electrochemical characteristics of thin-layer cells are evaluated in terms of flow rate and channel thickness. The adaptability of the flow cell for amperometric and electrochemiluminescence measurements is demonstrated. Also, a flow injection method comprising electrochemical generation followed by spectrophotometric detection is proposed for determination of bromide using the fabricated cell. The influence of chemical, electrochemical, and flow parameters on the absorbance and current signals are investigated, and under optimized conditions, the analytical features of the proposed method with respect to bromide detection are evaluated.     

Non-destructive radioanalytical technique in characterization of anion exchangers Amberlite IRN78 and Indion H-IP

The present study deals with characterization of industrial grade anion exchange resins Amberlite IRN78 and Indion H-IP for which non-destructive radiotracer technique using ¹³¹I and ⁸²Br was used. The radioisotopes were used to trace the kinetics of iodide and bromide ion-isotopic exchange reactions taking place in the two resins. It was observed that under identical experimental conditions of 40.0 °C, 1.000 g of ion exchange resins and 0.003 M labeled iodide ion solution for iodide ion-isotopic exchange reaction, the values of specific reaction rate (min^?1), amount of iodide ion exchanged (mmol), initial rate of iodide ion exchange (mmol min^?1) and log K _d were 0.285, 0.544, 0.155 and 12.6 respectively for Amberlite IRN78 resin, which was higher than 0.093, 0.315, 0.029 and 4.9 respectively as that obtained by using Indion H-IP resins. Also at a constant temperature of 40.0 °C, as the concentration of labeled iodide ion solution increases 0.001–0.004 M, the percentage of iodide ions exchanged increases from 68.10 to 74.00 % for Amberlite IRN78 resin, which was higher than the increase of 40.20–42.80 % as observed for Indion H-IP resins. The identical trend was observed for the two resins during bromide ion-isotopic exchange reaction. The overall results indicate that that under identical experimental conditions Amberlite IRN78 resins shows superior performance over Indion H-IP resins.     

Electrochemical liquid-membrane micro-extraction of bromide into an ethyl benzoate membrane supported on a graphite-epoxy composite electrode by cyclic voltammetry

Electrochemical liquid-membrane micro-extraction is a new sample preparation strategy, which combines liquid-membrane extraction with electrochemical detection. The introduction of electrochemistry can be used to control the redox states of analytes and thereby manipulate the extraction process. The bromide in aqueous solution was electrochemically oxidized to bromine and extracted into a liquid membrane composed of ethyl benzoate supported on a graphite-epoxy composite electrode with induction of iodide redox reactions. The technique enables concentrations as low as 1 nM of bromide to be determined by cyclic voltammetry by measuring the reduction current of extracted bromine. The reduction peak current is proportional to the logarithm of bromide concentration in the range from 1 nM to 10 μM under the optimal conditions. The extraction method offers a powerful way for the electrochemical detection of trace bromide.