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The C 60 -γ-cyclodextrin and Nafion chemically modified electrode exhibits two redox waves by cyclic voltammetry. Such an electrode will effect reduction and oxidation of cytochrome c and be capable of mediating the electron transfer to cytochrome c.
A stable electroactive thin film of poly(toluidine blue o) (PTOB) has been deposited on the surface of a glassy carbon electrode by cyclic voltammetry from an aqueous solution containing toluidine blue o (TOB). Cyclic voltammograms of PTOB indicate the presence of two redox couples and the formal potential shifts linearly in the negative direction with increasing solution pH with a slope of 58 and...
The coupling of adsorptive accumulation with catalytic reactions results in remarkably low (sub-picomolar) detection limits. This review assesses various strategies for attaining such dual-amplification effects, that lead to the most sensitive voltammetric technique, adsorptive-catalytic stripping voltammetry (AdCtSV).
Biomembrane-like polyionic complex, 2C 12 N + PA - , was prepared by reacting sodium polyacrylate (Na + PA - ) with didodecyldimethylammonium bromide (2C 12 N + Br - ). Stable thin films made from 2C 12 N + PA - , with incorporated myoglobin (Mb), on pyrolytic graphite (PG) electrodes were then characterized...
An electrocatalytic amperometric detector for the ion chromatographic determination of CN - is described. A conducting composite that is based on a graphite-loaded sol-gel material comprises the working electrode. The composite is doped with a Ru II metallodendrimer which is demonstrated to promote the electrochemical oxidation of CN - at potentials positive of 0.5 V vs...
Oxidation of a variety of compounds, including methionine (Met), using a complex formed between dirhodium(II) acetate and the lacunary form of phosphotungstic acid as the catalyst is effective over a wide range of conditions, including pH 2-10. Thus, amperometric detection at a composite in which this complex is immobilized in a sol-gel material does not place restrictions on selection of conditions...
Square-wave (SW) voltammetry in connection with a hanging mercury drop electrode has been applied for studying the reduction of Ge(IV) catalyzed by o-catechol after adsorptive preconcentration. Acetate buffer solutions with low and high analytical concentrations of o-catechol [with respect to that of Ge(IV)] have been used. Dependences of SW catalytic peaks on accumulation conditions have been attributed...
The C 60 -[dimethyl-(β-cyclodextrin)] 2 and nafion chemically modified electrode (CME) exhibits one electroreduction peak and two electro-oxidation peaks in a mixed solvent of water and acetonitrile (3:2, v/v) containing tetra-butylammonium perchlorate. The reduction of chloroacetic acids (mono-, di- and tri-) can be electrocatalyzed at this electrode, indicating that C 6...
2,2,6,6-Tetramethyl-4-hydroxypiperidine-1-oxyl (TMHPO) shows catalytic electroactivity in homogeneous oxidation of benzoyl hydrazine (BH) on a glassy carbon electrode. The catalytic current is affected by the concentration of TMHPO and the pH of the solution. A possible catalytic reaction mechanism is proposed and a non-toxic, convenient method for the determination of BH in the concentration range...
The thiolactic acid (TLA) self-assembled monolayer modified gold electrode (TLA/Au) is demonstrated to catalyze the electrochemical response of norepinephrine (NE) by cyclic voltammetry. A pair of well-defined redox waves were obtained and the calculated standard rate constant (k s ) is 5.11x10 -3 cm s -1 at the self-assembled electrode. The electrode reaction is...
We have developed a nucleic acid (NA) sensor based on mediated electrochemical oxidation of guanine residues. In this method, oligonucleotide probes are bound to a tin-doped indium oxide (ITO) electrode through a self-assembled phosphonate monolayer. The end carboxyl moiety of the monolayer is activated with carbodiimide and reacted with the amine group of a C6 alkyl linker which has been added to...
Electrochemical behavior of myoglobin (Mb) incorporated in polyacrylamide (PAM) hydrogel films cast on pyrolytic graphite (PG) electrodes were investigated. Mb-PAM film electrodes showed a pair of well-defined and nearly reversible cyclic voltammetric peaks for Mb Fe(III)/Fe(II) redox couple at about -0.27 (vs. SCE) in pH 5.5 buffers. The electron exchange of Mb with PG electrodes was greatly enhanced...
Metallophthalocyanine (MPc) and metalloporphyrin complexes as well as some metalloproteins including myoglobin, hemoglobin, cyanocobalamin and cytochrome c catalyse the detection of nitric oxide (NO). The catalytic process often involve changes in the oxidation state of the catalyst. These complexes catalyse both the reduction and oxidation of NO. MPc complexes containing electroactive central metals...
Electrochemistry and electrocatalysis of binuclear cobalt phthalocyaninehexasulfonate sodium salt (bi-CoPc) were investigated successfully in liquid crystal films of didodecyldimethylammonium bromide (DDAB) on pyrolytic graphite (PG) electrodes in aqueous solution. This new bi-CoPc-surfactant film modified electrode could reduce aggregation of bi-CoPc in aqueous solution, which was confirmed by the...
A reliable and very sensitive procedure for the determination of ultra trace of molybdenum is proposed. Molybdenum was determined by cathodic stripping differential pulse voltammetry based on the adsorption collection of the Mo(VI)–Tiron complex on a hanging mercury drop electrode (HMDE). The variation of peak current with pH, concentration of Tiron and chlorate, plus several instrumental parameters...
We propose a procedure to assemble monolayers of redox mediator, coenzyme, enzyme and stabilizing polyelectrolyte on an electrode surface using essentially electrostatic and complexing interactions. In a first step a monolayer of redox mediator, substituted nitrofluorenones, is adsorbed. In a second step, a layer of calcium cations is immobilized at the interface. It establishes a bridge between the...
The present paper describes the modification of hemoglobin (Hb)–octadecylamine (ODA) Langmuir–Blodgett (LB) film on a gold electrode surface to develop a novel electrochemical biosensor for the detection of hydrogen peroxide. Atomic force microscopy (AFM) image of Hb–ODA LB film indicated Hb molecules existed in ODA layer in a well-ordered and compact form. The immobilized Hb displayed a couple of...
Electrocatalytic oxidation and detection of hydrazine in pH 7.0 conditions were studied by using gold electrode modified with self-assembled monolayer (SAM) films of iron phthalocyanine (FePc) complex axially ligated to a preformed 4-mercaptopyridine SAMs. The anodic oxidation of hydrazine in neutral pH conditions with FePc-linked-mercaptopyridine-SAM-modified gold electrode occurred at low overpotential...
A new amperometric biosensor for hydrogen peroxide was developed based on cross-linking horseradish peroxidase (HRP) by glutaraldehyde with multiwall carbon nanotubes/chitosan (MWNTs/chitosan) composite film coated on a glassy carbon electrode. MWNTs were firstly dissolved in a chitosan solution. Then the morphology of MWNTs/chitosan composite film was characterized by field-emission scanning electron...
C 60 -modified glassy carbon electrode has been found to exhibit excellent electrocatalytic activity towards atenolol oxidation for its voltammetric determination at physiological pH. Lowering of overpotential associated with atenolol oxidation indicates electrocatalytic nature of electrode. Determination of atenolol was carried out at pH 7.2 at modified electrode and a well-defined oxidation...
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