LACCASE－BASED MICELLAR ENHANCED SPECTROFLUORIMETRIC DETERMINATION OF L－ASCORBIC ACID

ＬＡＣＣＡＳＥ－ＢＡＳＥＤ ＭＩＣＥＬＬＡＲ ＥＮＨＡＮＣＥＤ ＳＰＥＣＴＲＯＦＬＵＯＲＩＭＥＴＲＩＣ ＤＥＴＥＲＭＩＮＡＴＩＯＮ ＯＦ Ｌ－ＡＳＣＯＲＢＩＣ ＡＣＩＤ￥ＨｏｕＰｉｎｇＨＵＡＮＧ；ＲｕＸｉｕＣＡＩ；ＹｕＭｉｎＤＵａｎｄＹｕｎＥＺＥＮＧ...     

PHOTOINDUCED INTRAMOLECULAR CHARGE TRANSFER IN SELF－ASSEMBLY．1．AGGREGATION AND DUAL FLUORESCENCE OF ETHYL P－DIDECYLAMINOBENZOATE IN DIOXANE－WATER BINARY SOLVENT

ＰＨＯＴＯＩＮＤＵＣＥＤＩＮＴＲＡＭＯＬＥＣＵＬＡＲＣＨＡＲＧＥＴＲＡＮＳＦＥＲＩＮＳＥＬＦ－ＡＳＳＥＭＢＬＹ．１．ＡＧＧＲＥＧＡＴＩＯＮＡＮＤＤＵＡＬＦＬＵＯＲＥＳＣＥＮＣＥＯＦＥＴＨＹＬＰ－ＤＩＤＥＣＹＬＡＭＩＮＯＢＥＮＺＯＡＴＥＩＮＤＩＯＸＡＮ...     

DIRECT FORMATION OF TETRAQUINANE SKELETON BY INTRAMOLECULAR ARENE－OLEFIN meta－CYCLOADDITION

ＤＩＲＥＣＴＦＯＲＭＡＴＩＯＮＯＦＴＥＴＲＡＱＵＩＮＡＮＥＳＫＥＬＥＴＯＮＢＹＩＮＴＲＡＭＯＬＥＣＵＬＡＲＡＲＥＮＥ－ＯＬＥＦＩＮｍｅｔａ－ＣＹＣＬＯＡＤＤＩＴＩＯＮ￥ＣｏｎｇＺＨＡＮＧ；ＳｏｎｇＦｕＷＵａｎｄＸｉａｏｃｈｕａｎＧＵＯ（Ｉｎｓｔｉｔｕ...     

PREPARATION OF HETEROBIMETALLIC COMPLEXES BRIDGING WITH π，π－BOUND PHENYLCYCLOPENTADIENYL LIGAND AND X－RAY CRYSTAL STRUCTURE OF （TRICARBONYL－π－CHROMIUM）PHENYLCYCLOPENTADIENYLCOBALT DICARBONYL

ＰＲＥＰＡＲＡＴＩＯＮＯＦＨＥＴＥＲＯＢＩＭＥＴＡＬＬＩＣＣＯＭＰＬＥＸＥＳＢＲＩＤＧＩＮＧＷＩＴＨπ，π－ＢＯＵＮＤＰＨＥＮＹＬＣＹＣＬＯＰＥＮＴＡＤＩＥＮＹＬＬＩＧＡＮＤＡＮＤＸ－ＲＡＹＣＲＹＳＴＡＬＳＴＲＵＣＴＵＲＥＯＦ（ＴＲＩＣＡＲＢＯＮＹＬ...     

BIOTRANSFORMATION OF 2α，5α，10β，14β－TETRA－ACETOXY－4（20），11－TAXADIENE BY THE FUNGIJS CUNNINGHAMELLA ECHINULATA

ＢＩＯＴＲＡＮＳＦＯＲＭＡＴＩＯＮＯＦ２α，５α，１０β，１４β－ＴＥＴＲＡ－ＡＣＥＴＯＸＹ－４（２０），１１－ＴＡＸＡＤＩＥＮＥ　ＢＹ　ＴＨＥ　ＦＵＮＧＩＪＳ　ＣＵＮＮＩＮＧＨＡＭＥＬＬＡ　ＥＣＨＩＮＵＬＡＴＡＳｈａｎｇＨｕｔＨＵ；ＸｕＦａｎｇＴＩ...     

SYNTHESIS， STRUCTURE AND THERMOREANGEMENT OF TRTRA METHYLDISILANDIYL BIS（1－INDENYL） TETRACARBONYL DI－IRON

ＳＹＮＴＨＥＳＩＳ，ＳＴＲＵＣＴＵＲＥＡＮＤＴＨＥＲＭＯＲＥＡＮＧＥＭＥＮＴＯＦＴＲＴＲＡＭＥＴＨＹＬＤＩＳＩＬＡＮＤＩＹＬＢＩＳ（１－ＩＮＤＥＮＹＬ）ＴＥＴＲＡＣＡＲＢＯＮＹＬＤＩ－ＩＲＯＮ￥ＸｉｕＺｈｏｎｇＺＨＯＵ；ＢａｉＱｕａｎＷＡＮＧ；Ｓｈａ...     

IMFLUEHCE OF EDTA ON THE VOLTAMMETRIC RESPONSES OF IRONAND THE PITTING EFFECT OF CI－IOH IN BEUTRAL SODIUM SULFATE SOLUTION

ＩＭＦＬＵＥＨＣＥＯＦＥＤＴＡＯＮＴＨＥＶＯＬＴＡＭＭＥＴＲＩＣＲＥＳＰＯＮＳＥＳＯＦＩＲＯＮＡＮＤＴＨＥＰＩＴＴＩＮＧＥＦＦＥＣＴＯＦＣＩ－ＩＯＨＩＮＢＥＵＴＲＡＬＳＯＤＩＵＭＳＵＬＦＡＴＥＳＯＬＵＴＩＯＮＱｉａｎｇＳＨＥＨ；ＳｈｅｎＨａｏＣＨＥＮ...     

（E）－β，γ－UNSATURATED NITRILES FROM DIMETHYLSULFONIUM CYANOMETHYLIDE AND 9－ALKENYL－9－BORABICYCLO［3，3，1］NONANES

（Ｅ）－β，γ－ＵＮＳＡＴＵＲＡＴＥＤＮＩＴＲＩＬＥＳＦＲＯＭＤＩＭＥＴＨＹＬＳＵＬＦＯＮＩＵＭＣＹＡＮＯＭＥＴＨＹＬＩＤＥＡＮＤ９－ＡＬＫＥＮＹＬ－９－ＢＯＲＡＢＩＣＹＣＬＯ［３，３，１］ＮＯＮＡＮＥＳＮａｎＳｈｅｎｇＬＩ；ＭｉｎＺｈｉＤＥＮＧ；Ｙ...     

NEW OSCILLATING REACTIONS CATALYZED BY TETRAMETHYLTETRAAZACYCLOTETRAENE （TIM）NICKEL（Ⅱ）COMPLEX IN BROMATE－PYRUVIC ACID ──SULFURIC ACID SYSTEM

ＮＥＷ　ＯＳＣＩＬＬＡＴＩＮＧ　ＲＥＡＣＴＩＯＮＳ　ＣＡＴＡＬＹＺＥＤ　ＢＹ　ＴＥＴＲＡＭＥＴＨＹＬＴＥＴＲＡＡＺＡＣＹＣＬＯＴＥＴＲＡＥＮＥ　（ＴＩＭ）ＮＩＣＫＥＬ（Ⅱ）ＣＯＭＰＬＥＸ　ＩＮ　ＢＲＯＭＡＴＥ－ＰＹＲＵＶＩＣ　ＡＣＩＤ　──ＳＵＬＦＵ...     

STUDIES ON DOPAMINE RECEPTORS AND TETRAHYDROPROTOBERBERINES．Ⅱ．QUANTUM CHEMISTRY OF LIGAND－RECEPTOR INTERACTION

ＳＴＵＤＩＥＳＯＮＤＯＰＡＭＩＮＥＲＥＣＥＰＴＯＲＳＡＮＤＴＥＴＲＡＨＹＤＲＯＰＲＯＴＯＢＥＲＢＥＲＩＮＥＳ．Ⅱ．ＱＵＡＮＴＵＭＣＨＥＭＩＳＴＲＹＯＦＬＩＧＡＮＤ－ＲＥＣＥＰＴＯＲＩＮＴＥＲＡＣＴＩＯＮ￥ＹｕｎＴＡＮＧ；ＫａｉＸｉａｎＣＨＥＮ；Ｈｕａ...     

Reagentless enzyme electrode based on phenothiazine mediation of horseradish peroxidase for subnanomolar hydrogen peroxide determination

The development and characterization of a highly sensitive enzyme immobilized carbon based electrode for the determination of subnanomolar concentrations of hydrogen peroxide in aqueous samples is described. The biosensor consists of horseradish peroxidase (HRP) immobilized in solid carbon paste along with a suitable redox mediator. The latter allows the acceleration of the electroreduction of HRP in the presence of hydrogen peroxide. Several phenothiazines as mediators are investigated in a comparative manner and with respect to dimethylferrocene using cyclic voltammetry and amperometry. Insolubilization of the HRP in the solid carbon paste is achieved by cross-linking the enzyme with glutaraldehyde and bovine serum albumin. Several experimental parameters such as pH, mediator and enzyme content are considered. The hydrogen peroxide determination is better carried out in 0.1 M acetate buffer, pH 4.5, by amperometry at an applied potential of 0.0 V versus Ag/AgCl, 3 M NaCl concentration and by using the phenothiazine base as redox mediator. The biosensor response is linear over the concentration range 2 nM-10 microM with a detection limit of 1 nM. The linear range of the hydrogen peroxide response without a mediator in the biosensor is found between 2 and 40 microM. The biosensor can be used for more than 180 measurements. Additional modification of the electrode by incorporation of Nafion SAC-13 microparticles in the solid carbon paste allows detection of concentrations of hydrogen peroxide as low as 0.1 nM.     

Renewable silica sol–gel derived carbon composite based glucose biosensor

An amperometric mediated glucose biosensor has been developed based on a sol–gel derived carbon composite material. Glucose oxidase and the mediator vinylferrocene have been immobilised within the porous, rigid and organically modified silicate network in the composite material. The organic group in the silicate network controls the hydrophobicity of the electrode surface and thus limits the wettability of the electrode surface. Various important fabrication factors controlling the biosensor performance have been investigated systematically. The glucose biosensor can be renewed easily in a reproducible manner by a simple polishing step and it has a long operational lifetime. Applicability of the biosensor has been demonstrated in real samples and the results obtained by this biosensor corroborate well with a classical UV spectrophotometric technique.     

A Mediator‐Free Bienzyme Amperometric Biosensor Based on Horseradish Peroxidase and Glucose Oxidase Immobilized on Carbon Nanotube Modified Electrode

Multiwalled carbon nanotube (CNT) modified glassy carbon electrode immobilized with horseradish peroxidase (HRP) in Nafion coating showed direct electron transfer between HRP enzyme and the CNT‐modified electrode. A mediator‐free bienzyme glucose biosensor based on horseradish peroxidase and glucose oxidase was constructed. The bienzyme biosensor exhibited a high sensitivity for glucose detection at zero applied potential.     

Effects of nonionic surfactants on electrochemical behavior of ubiquinone and menaquinone incorporated in a carbon paste electrode

A carbon paste electrode, in which the carbon particles were coated with a thin layer of a nonionic surfactant (NIS), was constructed with a pasting liquid containing ubiquinone (UQ) or menaquinone (MQ). It has revealed that the layer acts not only as a diffusion barrier but also as a matrix for the redox reaction of quinones at electrode surface, and its effects on the electrochemical behavior of quinones depend on both the physico-chemical structure of a surfactant and the kind of quinones. Further, such a modification was applied to the preparation of an enzyme electrode in which the quinone molecule act as a redox mediator and the influences on the sensitivity of the glucose biosensor was demonstrated.     

Electrochemical performances of C/Fe nanocomposite and its use for mediator-free glucose biosensor preparation

C/Fe nanocomposite (CFN) was synthesized by a procedure similar to an exfoliation/adsorption process to intercalate Fe³⁺ into graphite oxide (GO) layers and would be reduced in a H₂ atmosphere. The results of X-ray diffractometry (XRD) and transimission electron microscopy (TEM) show that the form of CFN is carbon nanotube-Fe nanoparticle composite with α-Fe distributed on the nanotube wall. Paste electrode has been constructed using CFN mixed with paraffin. The electrochemical characteristics of such carbon-Fe nanocomposite paste electrode (CFNPE) has been compared with that of carbon paste electrode (CPE) and evaluated with respect to the electrochemistry of potassium ferricyanide, ascorbic acid and cysteine by cyclic voltammetry. CFNPE can accelerate the electron-transfer to improve the electrochemical reaction reversibility. To fabricate the third-generation glucose biosensor, glucose oxidase (GOD) was immobilized on CFNPE surface with Nafion covered after a pretreatment. Oxygen, ascorbic acid and uric acid have no interference with the glucose detection. The biosensor displays a remarkable sensitivity and stability and the results used in the determination of glucose in the human serum samples are satisfactory.     

Amperometric Cholinesterase Biosensors with Carbon Paste Electrodes Modified with Cobalt Phthalocyanine

Biosensors based on a carbon paste electrode with immobilized cholinesterase and cobalt(II) phthalocyanine as a mediator are studied. Electrochemical characteristics of the biosensors are investigated in relation to the carbon paste composition, the enzyme and mediator immobilization procedures, nature of the protective film and procedure of its application, and also storage conditions of the electrodes. A method is suggested for fabricating a cholinesterase biosensor with cobalt(II) phthalocyanine mediator, providing the maximum electrocatalytic response in electrooxidation of butyrylthiocholine iodide (substrate for cholinesterase).     

A Novel Amperometric Hydrogen Peroxide Biosensor Based on Horseradish Peroxidase Incorporated in Organically Modified Sol-Gel Glass Matrix/Graphite Paste with Multiwalled Carbon Nanotubes

We herein report an electrochemical hydrogen peroxide sensor based on horseradish peroxidase immobilized in organically modified sol-gel glass (ormosil) with mediator ferricyanide along with multiwalled carbon nanotubes (mwcnts). The ormosil material is converted to fine powder followed by incorporation within graphite paste electrode. The electrochemistry of redox materials encapsulated within ormosil has been studied. The requirement of mwcnts is examined. The ormosil prepared with optimum concentration of mwcnts shows better redox electrochemistry as compared to that made without mwcnts. The biosensor has been characterized by cyclic voltammetry and chroanoamperometry. The performance, stability, and reproducibility of a new peroxide biosensor are reported.     

Amperometric Lactate Biosensor Based on Carbon Paste Electrode Modified with Benzo[c]cinnoline and Multiwalled Carbon Nanotubes

Amperometric lactate biosensor based on a carbon paste electrode modified with benzo[c]cinnoline and multiwalled carbon nanotubes is reported. Incorporation of benzo[c]cinnoline acting as a mediator and multiwalled carbon nanotubes providing a conduction pathway to accelerate electron transfer due to their excellent conductivity into carbon paste matrix resulted in a high performance lactate biosensor. The resulting biosensor exhibited a fast response, high selectivity, good repeatability and storage stability. Under the optimal conditions, the enzyme electrode showed the detection limit of 7.0×10^?8 M with a linear range of 2.0×10^?7 M–1.1×10^?4 M. The usefulness of the biosensor was demonstrated in serum samples.     

Mediatorless amperometric bienzyme glucose biosensor based on horseradish peroxidase and glucose oxidase cross-linked to multiwall carbon nanotubes

We report on a bienzyme-channeling sensor for sensing glucose without the aid of mediator. It was fabricated by cross-linking horseradish peroxidase (HRP) and glucose oxidase (GOx) on a glassy carbon electrode modified with multiwalled carbon nanotubes (MWNTs). The bienzyme was cross-linked with the MWNTs by glutaraldehyde and bovine serum albumin. The MWNTs were employed to accelerate the electron transfer between immobilized HRP and electrode. Glucose was sensed by amperometric reduction of enzymatically generated H₂O₂ at an applied voltage of ?50 mV (vs. Ag/AgCl). Factors influencing the preparation and performance of the bienzyme electrode were investigated in detail. The biosensor exhibited a fast and linear response to glucose in the concentration range from 0.4 to 15 mM, with a detection limit of 0.4 mM. The sensor exhibited good selectivity and durability, with a long-term relative standard deviation of <5 %. Analysis of glucose-spiked human serum samples yielded recoveries between 96 and 101 %.

Amperometric Glucose Biosensor Based on Glucose Oxidase Encapsulated in Carbon Nanotube–Titania–Nafion Composite Film on Platinized Glassy Carbon Electrode

A highly sensitive and selective glucose biosensor has been developed based on immobilization of glucose oxidase within mesoporous carbon nanotube–titania–Nafion composite film coated on a platinized glassy carbon electrode. Synergistic electrocatalytic activity of carbon nanotubes and electrodeposited platinum nanoparticles on electrode surface resulted in an efficient reduction of hydrogen peroxide, allowing the sensitive and selective quantitation of glucose by the direct reduction of enzymatically‐liberated hydrogen peroxide at ?0.1 V versus Ag/AgCl (3 M NaCl) without a mediator. The present biosensor responded linearly to glucose in the wide concentration range from 5.0×10^?5 to 5.0×10^?3 M with a good sensitivity of 154 mA M^?1cm^?2. Due to the mesoporous nature of CNT–titania–Nafion composite film, the present biosensor exhibited very fast response time within 2 s. In addition, the present biosensor did not show any interference from large excess of ascorbic acid and uric acid.