多巴胺在硫堇衍生化自组装膜修饰金电极上的伏安行为及其安培测定

研究了多巴胺在硫堇衍生化自组装膜修饰电极上的电化学行为。ＤＡ在该修饰电极上的ΔＥｐ－７０ｍＶ，循环伏安峰形对称，氧还峰电流之比接近１，为准可逆反应。研究了温度，Ｐｈ对ＤＡ氧还原的影响，并求得了其热力学参数。     

乙酰半胱氨铜自组装修饰金电极作为生物传感器测定一氧化氮

将铜离子共价键合到自组装在Au电极表面的乙酰半胱胺单分子层上,获得了乙酰半胱胺铜自组装单分子膜修饰电极(CuACYS CME),研究了它的电化学性质,并采用扫描电子显微镜(SEM),X射线荧光仪(XRFS),X射线光电子能仪(XPS)以及循环伏安法(CV)对该电极表面进行了表征。在pH 3.0时,循环伏安图显示Cu修饰层存在一对氧化还原峰,其峰电位分别为Vp1a=246 mV,Vp1c=101 mV(vs.SCE)。它的表面电子转移系数α为0.52,速率常数Ks=0.04 s-1,表面覆盖度Γ=1.2×10-10mol/cm2,属于单分子层吸附。在pH 2.0~5.0的NaAc底液中,该电极对NO的还原有催化作用,pH 3.0时NO的还原过电位为VpcⅡ=-672 mV,较在裸电极上(-1.1V)降低了约600 mV,采用示差脉冲伏安法(DPV)测定催化电流与NO的浓度在3.1×10-9~4.7×10-8mol/L范围内呈良好的线性关系。NO催化还原过程的异相电子转移速率常数为3.12×10-3cm/s。     

邻氨基硫酚自组装膜修饰电极测定多巴胺

邻氨基硫酚自组装膜修饰电极测定多巴胺;多巴胺;邻氨基硫酚;自组装膜;金电极;方波伏安法     

维生素B_1自组装膜修饰金电极对多巴胺、尿酸的电催化作用

用维生素B1(VB1)在金电极上进行自组装,制备了VB1自组装膜修饰金电极(VB1-Au/SAMs/CME).利用循环伏安法初步研究了此自组装单分子膜修饰电极的电化学行为.结果表明: VB1在金电极表面具有特性吸附.以\3-/ 4-氧化还原电对为探针,考察了VB1自组装膜修饰金电极的电化学性质, VB1自组装膜的存在对\3-/4-的电子转移具有明显的阻碍作用.研究了多巴胺(DA)和尿酸(UA)在此电极上的电化学行为.实验结果表明, DA和UA在此电极上均可被电催化氧化.差分脉冲伏安(DPV)氧化峰电流与DA浓度在2.0×10-5～4.0×10-4 mol/L范围内呈线性关系;测定UA的线性范围为6.0×10-5～2.2×10-4 mol/L,而且可实现这两种物质的同时测定.     

二乙腈基二硫纶自组装膜修饰金电极对多巴胺的电化学催化作用

将经抛光清洗的金电极置于5mmol·L-1 cis-1,2-二腈基乙烯-1,2-二硫醇钠(简称二腈基二硫纶,Na2mnt)溶液中浸泡24h,制得Na2mnt自组装膜修饰的金电极mnt-SAM/Au,用电化学方法研究了上述修饰电极的电化学性质。结果表明:多巴胺在mnt-SAM/Au修饰电极上的氧化还原可逆性显著变好,峰电流增加;此氧化还原过程受扩散控制,多巴胺在电极上无吸附,电极不受污染。由于多巴胺是生物物质,选用在pH 7.00的磷酸盐介质中检测。在所选定的条件下,多巴胺的浓度在4.0×10-6~2.0×10-4 mol·L-1之间与其相应的峰电流(i/nA)之间呈线性关系。     

硫堇衍生化自组装膜修饰金电极的电化学性质及其对抗坏血…

将硫堇共价键合到自组装在金电极表面的半胱胺单分子层上，制成了衍生化自组装单分子膜修饰电极，并用电化学方法研究了它的电化学性质，循环伏安图显示其在ｐＨ＝７．７的磷酸盐缓冲液中，于－０．４５～＋０．５０Ｖ（ｖｓ．ＳＣＥ）范围内有２对氧化还原峰，峰电位分别为Ｅｐａ＝２１４ｍＶ，Ｅｐｃ＝８２ｍＶ，Ｅ＾２ｐａ＝－７５ｍＶ，Ｅ＾２ｐｃ－－１６０ｍＶ（ｖｓ．ＳＣＥ），ｐＨ在５．０～９．０范围内，峰１有２个质子参     

铜氮杂配合物修饰金电极对抗坏血酸的分析测定

本实验制备了一种新型的氮杂铜配合物修饰金电极,该电极可用于抗坏血酸的测定。采用循环伏安法和扫描电化学显微镜技术对电极进行了表征。该修饰电极可催化氧化抗坏血酸,相对于裸电极抗坏血酸在修饰电极上氧化电位移动了250mV,并且氧化电流在抗坏血酸的浓度为5.0×10−7 to 4.0×10−5 mol/L时呈线性关系,检测限为4.8×10-8 mol/L。用此方法测定抗坏血酸与文献报道的测定结果一致,这表明该电极可用作抗坏血酸测定的电化学传感器。     

Cu(CMQA)(H2O)配合物修饰电极作为识别和测定变性核酸的电化学探针

合成了N-羧甲基-L-蛋氨酸-N-′8-喹啉酰胺与铜(Ⅱ)的配合物[Cu(CMQA)(H2O)],并将它修饰于玻碳电极上。用循环伏安法检验了该修饰电极的电化学特性,发现在pH 5.0的乙酸盐缓冲底液中,电极对变性核酸(ssDNA)具有电化学活性;在循环伏安图上于(Epa)180 mV及(Epc)320 mV处出现氧化还原电位峰;并发现ssDNA的浓度变化引起其峰电流的变化。当用差示脉冲伏安法(DPV)试验ssDNA浓度与峰电流的关系时,结果表示随ssDNA浓度的增加,峰电流(ip)也随之增加,且ssDNA浓度在0.05~9.0 mg.L-1范围内与ip值的增加呈线性关系。但以小牛胸腺DNA(ctDNA)及鱼精RNA(yRNA)作试验时,其浓度变化不引起峰电流的变化,在此基础上建立了一种测定ssDNA的新方法。应用于合成试样分析时,根据结果算得方法的检出限(3σ)为25μg.L-1,回收率在95%~105%之间。     

多巴胺在电沉积石墨烯修饰碳分子线电极上的电化学测定

以分子线二苯乙炔为修饰剂和粘合剂制备了一种新型的碳糊电极-碳分子线电极(CMWE),并以其为基底电极采用电化学还原法将石墨烯(GR)沉积到CMWE表面得到电沉积石墨烯修饰碳分子线电极(GR/CMWE)。考察了多巴胺(DA)在该修饰电极上的电化学行为。实验结果显示DA在GR/CMWE上出现了1对峰形良好的氧化还原峰,与裸电极相比,该氧化还原峰的电流增大,峰电位差减小,表明修饰电极对DA的电化学反应有催化作用。在最佳实验条件下峰电流与DA浓度在8.0×10-7~2.0×10-3mol/L范围内呈良好的线性关系,检出限(3σ)为2.55×10-7mol/L。将该电极用于多巴胺注射液样品的检测,结果满意。     

Cu(CMQA)(H2O)配合物修饰电极作为识别和测定变性核酸的电化学探针

合成了N-羧甲基-L-蛋氨酸-N'-8-喹啉酰胺与铜(Ⅱ)的配合物[Cu(CMQA)(H2O)],并将它修饰于玻碳电极上.用循环伏安法检验了该修饰电极的电化学特性,发现在pH 5.0的乙酸盐缓冲底液中,电极对变性核酸(ssDNA)具有电化学活性;在循环伏安图上于(Epa)180 mV及(Epc)320 mV处出现氧化还原电位峰;并发现ssDNA的浓度变化引起其峰电流的变化.当用差示脉冲伏安法(DPV)试验ssDNA浓度与峰电流的关系时,结果表示随ssDNA浓度的增加,峰电流(ip)也随之增加,且ssDNA浓度在0.05～9.0 mg·L-1范围内与ip值的增加呈线性关系.但以小牛胸腺DNA(ctDNA)及鱼精RNA(yRNA)作试验时,其浓度变化不引起峰电流的变化,在此基础上建立了一种测定ssDNA的新方法.应用于合成试样分析时,根据结果算得方法的检出限(3σ)为25μg·L-1,回收率在95%～105%之间.     

芦丁在铂纳米/碳纳米管修饰电极上电化学行为研究

通过电沉积的方式在多壁碳纳米管(MWCNTs)修饰玻碳电极表面上沉积铂(pt)纳米粒子,并运用循环伏安法(CV)、示差脉冲伏安法(DPV)探讨了芦丁在铂纳米/碳纳米管/玻碳电极上的电化学行为.实验结果表明,芦丁在该修饰电极上呈现一对良好氧化还原峰,其氧化峰电流与浓度在3.2×10(-8)～1.2×10(-5)mol/L...     

Electrochemical Determination of Capsaicin and Silymarin Using a Glassy Carbon Electrode Modified by Gold Nanoparticle Decorated Multiwalled Carbon Nanotubes

The goal of this study was to develop a suitable electroanalytical method for the determination of primary compounds in the extracts of capsaicin and silymarin. For this purpose, a glassy carbon electrode immobilized with multiwalled carbon nanotubes decorated with gold nanoparticles was characterized by high resolution transmission electron microscopy and attenuated total reflectance infrared spectroscopy. The developed electrochemical sensor had a linear dynamic range from 0.15 to 35.0 µM. In addition, the limits of quantification for silymarin and capsaicin with the gold nanoparticle decorated multiwalled carbon nanotubes were 0.1564 and 0.2761 µg L^?1 with relative standard deviations (n = 3) of 1.65% and 2.09% and equivalent mass percentages of 93.33% and 62.02%, respectively. The methodology may be employed for the determination of capsaicin and silymarin in pharmaceutical and food products.     

Determination of Tetracycline at a UV‐Irradiated DNA Film Modified Glassy Carbon Electrode

In this study, interaction of tetracycline (TC) and DNA in the Britton? Robinson buffer solution (BR) was studied by cyclic voltammetry. The experimental results reveal that TC can bind strongly to DNA and the association constant and binding number between TC and DNA was obtained. Then DNA was immobilized on a glassy carbon electrode by UV‐irradiation. Through this process, water‐soluble DNA was converted into insoluble materials, and a stable DNA film was formed on the electrode. The electrochemical oxidation behavior of TC was studied at UV‐irradiated DNA film modified glassy carbon electrode (UV‐DNA‐GCE). The response of modified electrode was optimized with respect to pH, accumulation time, ionic strength, drug concentration and other variables. TC at the surface of modified electrode showed a linear dynamic range of 0.30–90.00 µM and a detection limit of 0.27 µM. To demonstrate the applicability of the modified electrode, it was used for the analysis of real samples such as pharmaceutical formulations and milk.     

Anodic Stripping Voltammetric Determination of Iron(II) at a Carbon Paste Electrode Modified with Dithiodianiline (DTDA) and Gold Nanoparticles (GNP)

A differential pulse anodic stripping voltammetric procedure was developed for the determination of trace amounts of iron(II) in the presence of iron(III) at a carbon paste electrode (CPE) modified with dithiodianiline and gold nanoparticle. At the pH working of 3.0, a wide concentration range from 0.1 nM to 100 nM was observed with the detection limit of 0.05 nM. The relative standard deviation for a solution containing 50 nM of iron(II) was found to be 3.11 % (n=9). Possible interferences from the coexisting ions were also investigated. The validity of the method and applicability of the sensor were successfully tested by determining of iron(II) in lentil, wheat seed and barley seed samples.     

Studies of an Alkaline Activated Glassy Carbon Electrode on the Determination of Purines and DNA

Performance of glassy carbon electrode on the determination of purines and DNA was found to be improved dramatically by activating the GCE with a simple but effective electrochemical pretreatment. Characteristics such as lowering of oxidation potential, enhancement of peak current and elimination of fouling effect were found for the activated GCE. By flow injection analysis, good reproducibility with relative standard deviations of 0.59 and 2.01% (n = 11) and rather low detection limits of 0.6 + 0.1 and 3.0 ± 0.4 nM can be obtained for the analysis of guanine and adenine. Solutions of denatured calf thymus DNA were analyzed by differential pulse voltammetry with the activated GCE. Good agreement between the obtained results and the known values confirms the feasibility of the activated GCE for DNA analysis.     

聚邻氨基对酚磺酸修饰电极测定尿酸

尿酸(UA)是核蛋白和核酸的代谢产物,人体内尿酸的水平与肝脏疾患[1]、肾病[2]以及心血管疾病[3]等有着密切的关系.因此,对人体体液中尿酸的定量分析无论在药物控制方面还是在临床诊断方面都具有重要意义.     

Electrochemical behavior of dopamine at a quercetin-SAM-modified gold electrode and analytical application

A stable quercetin–thioglycolic acid-modified gold electrode (Qu–TCA/Au) was prepared as a self-assembled monolayer (SAM) and its electrochemical behavior was investigated by electrochemical methods. In 0.05-M phosphate buffer solution (pH 7.0) quercetin exhibits quasi-reversible signals at the Qu–TCA/Au electrode. The stability of the quercetin-modified gold electrode is very good. The quercetin self-assembled monolayer is an effective mediator for the oxidation of dopamine, which was investigated by cyclic voltammetry and differential pulse voltammetry. Ascorbic acid does not interfere with determination of dopamine at an electrode modified with a mixture of quercetin–thioglycolic acid and quercetin–11-mercaptoundecanoic acid. This modification allows dopamine to be determined in the presence of ascorbic acid in the range from 3×10^–5 to 3×10^–4 M. The detection limit is 1×10^–6 M. Scanning electrochemical microscopy (SECM) was employed to study the electrochemical performances of the modified gold electrode indicating different feedback modes at differently modified surfaces.     

Differential Pulse Voltammetric Determination of Uric Acid on Carbon‐Coated Iron Nanoparticle Modified Glassy Carbon Electrodes

A carbon‐coated iron nanoparticles (CIN, a new style fullerence related nanomaterial) modified glassy carbon electrode (CIN/GCE) has been developed for the determination of uric acid (UA). Electrochemical behaviors of UA on CIN/GCE were explored by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that the voltammetric response of UA on CIN/GC was enhanced dramatically because of the strong accumulation effect of CIN and the large working area of the CIN/GC electrode. The parameters including the pH of supporting electrolyte, accumulation potential and time, that govern the analytical performance of UA have been studied and optimized. The DPV signal of UA on CIN/GCE increased linearly with its concentration in the range from 5.0×10^?7 to 2.0×10^?5 M, with a detection limit of 1.5×10^?7 M (S/N=3). The CIN/GCE was used for the determination of UA in samples with satisfactory results. The proposed CIN/GCE electrochemical sensing platform holds great promise for simple, rapid, and accurate detection of UA.     

聚苏木精修饰玻碳电极测定酪氨酸

通过在玻碳电极上电聚合聚苏木精的方法制备了聚苏木精修饰电极,研究了酪氨酸在修饰电极上的电化学行为。在0.1 mol/L磷酸盐缓冲溶液(pH3.0)中,富集电位为-0.3 V,富集时间为180 s,氧化峰电流与酪氨酸的浓度在5.0×10-6～1.0×10-4mol/L的范围内呈良好的线性关系,检出限为3.0×10-7mo...