One Step Fabrication of Microbiosensor Prepared by the Codeposition of Enzyme and Platinum Particles

Abstract

Electrochemical incorporation of enzyme molecules into the growing matrix of platinum black particles is employed for the microfabrication of the enzyme electrode. Two electrochemical processes, i.e., electrochemical adsorption of enzyme molecules and electrolytic (reductive) deposition of metallic microparticles from its complex compound, are simultaneously carried out by using a microelectrode whose diameter is below 50 μm. A glucose sensor, a glucose oxidase-incorporated microelectrode, demonstrates high performance with high sensitivity and fast responsiveness.     

Dramatic Effects of Ionic Liquid on Platinum Electrode Surface and Electron‐Transfer Rates of meso‐Tetraphenylporphyrins

The effect of addition of a room temperature ionic liquid, 1‐butyl‐3‐methyl imidazolium hexafluorophosphate [bmim][PF₆], on the electrochemical behavior of different free‐base para‐substituted meso‐tetraphenylporphyrins in dichloromethane solution has been studied using cyclic voltammetric technique. It has been found that the ionic liquid has the ability to regenerate platinum electrode surface and improves the reversibility of electrode processes. This has been true for the case of all the porphyrins studied.     

The Application of an Enzyme Electrode for Blood Glucose Determination in the Automated Flow System

Abstract

An enzyme electrode containing immobilized GOD was utilized in a continuous flow system for the automatical determination of glucose. The advantages of kinetic measurement of H₂ O ₂ are used. Characteristic parameters of device and results in routine are shown. Particular advantages are: low requirement on material (20 μl blood, < l μg GOD/measurement) and time (60 samples/h at 15 sec response time) as well as sufficient precision and accuracy (S % - serial: < 2 %).     

镀铂金电极上电沉积碳纳米管-葡萄糖氧化酶-壳聚糖的新型生物传感器

通过电化学沉积将壳聚糖、葡萄糖氧化酶和碳纳米管固定到镀铂金电极上,制备了一种新型葡萄糖生物传感器.探讨了铂的电沉积时间、壳聚糖化学沉积时间、缓冲溶液pH和工作电位等对该牛物传感器的影响.实验结果表明,该生物传感器线性范围为1×10~(-6)1.2×10~(-2)mol/L,相关系数为0.9974,检测限为5.0×10~(-7)mol/L,响应时间≤8 s;血清中的尿酸、抗坏血酸等对葡萄糖的测定无干扰.利用该生物传感器测定了人血清中的葡萄糖,回收率在97%～105%之间.该生物传感器线性范围较宽,灵敏度高,响应迅速,抗干扰能力强,有望成为一种可推广的新型葡萄糖检测器.     

分子印刷技术铂微粒修饰电极及甲醇的电催化氧化

利用分子印刷技术(Molecular Imprinting Technology,MIT),将铂微粒沉积到谷胱甘肽自组装膜的针孔上,并用循环伏安法研究了甲醇在该电极上的电催化氧化行为。实验结果表明,该电极对甲醇电化学氧化呈现出较高的催化活性,活性高低与载铂量、溶液pH值及电极表面铂微粒所处的微环境有关。     

Adsorption of Carbon Monoxide on Platinized Platinum Electrode with Preadsorbed Iodine and Iodide Anions

Adsorption of carbon monoxide in the presence of adlayers formed upon exposure of Pt/Pt to I^– anions and I₂ (0.5 M ₂SO₄ as the supporting electrolyte) is studied using the method of electrode washing. Transients of current and potentiodynamic curves show that the displacement of iodine adatoms from the Pt/Pt surface by CO is virtually complete when CO is adsorbed in the range of hydrogen adsorption potentials (E 0.35 V (RHE)) and incomplete at higher potentials. It is concluded that the bond formed by iodine adatoms with the surface strengthens with an increase in the potential. Possible reasons for the striking difference in the behavior of adatomic monolayers formed from KI and I₂ solutions is discussed. The surface charge of Pt/Pt is observed to drastically change as a result of the displacement of iodine adatoms by carbon monoxide.     

Electrochemical Behaviour of a Lipid Modified Enzyme Electrode

Abstract

The modification of the surface of a platinum electrode by coating with a layer of a lipid mixture (asolectin), allows the relative measurement of hydrogen peroxide in the presence of interfering analytes. The lipid-enzyme complex and the platinum amperometric sensor offer greater selectivity and extended stability of the resulting probe. Measurements of glucose with the glucose oxidase enzyme and detection of the liberated hydrogen peroxide have been performed as a model system. Linear response of the signal versus glucose concentration was observed in the range of glucose concentration 1.10^?3 ? 1.10^?5 M with a response time of 20 s. The interferences of ascorbic acid, uric acid, iron (II), paracetamol, tyrosine and glutathion can be drastically minimized by appropriate adjustment of the amount of lipid contained in the biocatalyst layer.     

A Creatinine Specific Enzyme Electrode

Abstract

An extremely specific creatinine electrode was successfully developed for selective analysis of aqueous creatinine with a linear response over the range from 5 mg/l to 100 mg/l. The endogenous and exogenous species generally present in the serum do not interfere in the assay with the exception of ammonia. With the use of the electrode serum samples containing high creatinine can be assayed directly after pre-treatment. However, the electrode is not sensitive enough to detect the normal level serum creatinine due to the dilution of the serum after treatment.     

Kinetic Analysis of an Enzyme-containing Polymer Modified Electrode

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Adsorption Pre-Concentration and Analysis of Dopamine at Platinum Electrode Surfaces

Abstract

Studies indicated that dopamine and other catechol-and phenol-containing amines adsorb rapidly onto platinum surfaces. Using this phenomenon to pre-concentrate these compounds at a platinum electrode prior to differential pulse voltammetric analysis, a minimum detectable dopamine concentration of 5 × 10 M can be directly determined.     

脱乙酰壳多糖化学修饰电极测定铂的研究

用脱乙酰壳多糖修饰电极为工作电极，阳极溶出伏安法测定痕量铂。在ｐＨ＝２￣３的ＫＣｌ－ＨＣｌ底液中，－０．３Ｖ富集２ｍｉｎ，静止１５ｓ，以０．２Ｖ／ｓ扫速阳极溶出，峰电位在－０．１６Ｖ（ｖｓ．ＳＣＥ），铂（Ⅳ）离子浓度在０．５￣５．０μｇ／ｍＬ范围内与峰高呈线性关系。富集１０ｍｉｎ后，可检测０．０２５μｇ／ｍＬ铂（Ⅳ）。该法用于贵金属矿样的测定，无需分离，结果满意。用循环伏安法、紫外光谱和拉曼光谱研     

The Potentiodynamic Electrooxidation of Glycerol on Platinized Platinum Electrodes

Abstract

The electrooxidation of adsorbed glycerol species on platinized platinum electrodes in 1 N H₂SO₄ was studied by cyclic voltammetry and the potential step method. The main conclusions are: the electrooxidation of glycerol at potentials lower than 1.2 V (vs, RHE) is a complex reaction in which more than one adsorbed intermediates are probably involved. The adsorbed intermediates exhibit ageing effects, at higher potentials a chemical interaction between glycerol and adsorbed oxygen occurs and the overall process is controlled by mass transfer.     

Platinum Nanoparticles Supported on Graphite Nanofibers Prepared by Microwave Irradiation and Its Electrocatalytic Activity

Platinum nanoparticles supported on graphite nanofibers (GNFs) were prepared by microwave assistant heating polyol process. TEM images showed that microwave prepared Pt nanoparticles supported on GNFs were small and uniform, and the average diameter was about 3.4 nm. Cyclic voltammetric test showed that Pt/GNFs exhibited very high electrocatalytic activity for methanol oxidation.     

Radioactive Tracer Study of the Displacement of Iodine Adatoms from Platinized Platinum Electrode by Carbon Monoxide

Radioactive tracer studies confirm the earlier electrochemical results that carbon monoxide can virtually completely displace iodine adatoms. For the first time, it is found that iodine adatoms are not displaced by carbon monoxide when iodide anions are adsorbed in the presence of an upd silver monolayer. The possible reasons for the effect observed are discussed.     

A Micro Planar Ampehometric Glucose Sensor Using an Isfet as a Reference Electrode

Abstract

A very small glucose sensor has been realized, which consists of a gold working electrode with a glucose oxidase immobilized membrane on it, and a gold counter electrode, all made on a sapphire substrate. By using the pH sensitive ISFET as a reference electrode, the potential for a solution, whose pH is constant, can be measured and irreversible metal electrodes, such as gold or platinum, can be used as working electrode and counter electrode. The sensor is very suitable for miniaturizing and mass production, because the Integrated Circuit (IC) fabrication process can be applied. The glucose oxidase immobilized membrane was also deposited by a lift off method, one of the IC processes. A glucose concentration, from 1 to 100 mg/dl, was measured with good linear current output.     

铂溶胶修饰电极对鲁米诺电化学发光的增敏作用

用化学还原法制备了纳米铂溶胶,透射电鏡显示其粒径约为5 nm,经过电化学沉积可将铂溶胶修饰于铂盘电极上。在中性介质中,铂溶胶修饰电极对溶液中鲁米诺的电化学发光具有明显的增敏作用,且具有较好的稳定性。维生素C对此增敏的电化学发光有强烈的猝灭作用。因此,利用该修饰电极可测定痕量维生素C。灵敏度极高,检出限为2.0×10-13mol/L,并实现了片剂的检测,方法准确、可靠。     

Mediated Enzyme Electrode for the Determination of L-Glutamate

Abstract

A mediated enyme electrode was developed for the determination of L-glutamate, based on the immobilization of L-glutamate oxidase from Streptomyces sp. X 119–6. A graphite working electrode was used with 1,1 dimethylferrocene (DMF) as electron mediator. The electrode responded linearly to L-glutamate over the range 0.2 to 2 mM (0.029–0.29 g/l). The enzyme electrode was applied to the measurement of L-glutamate in various foodstuffs.     

Enzyme Electrode with Collagen-Immobilized Cholesterol Oxidase for the Microdetermination of Free Cholesterol

Abstract

Cholesterol oxidase has been immobililzed on collagen films associated to an electrochemical sensor to form a “cholesterol electrode”. The electrode poised at a potential of + 650 my vs Ag/AgCl detects the hydrogen peroxide produced in the enzymatic reaction. This device presents a very high sensitivity and a wide range of linearity (10^?7 M - 0.8.10^?4 M). The use of a non enzymatic electrode associated with the enzymatic one allowed the detection and correction of electrochemical interferences when applied to human sera for free cholesterol determination.