Amperometric enzyme electrodes. Part 8. Enzyme electrodes for choline + betaine aldehyde and hypoxanthine + xanthine. A kinetic model for a one-enzyme sequential substrate system

Conductive Organic Complex Salt TTF‐TCNQ as a Mediator for Biosensors. An Overview

“…The lethal dose (LD 50 ) and the maximum tolerated dose (MTD) of TTF and TCNQ have been determined by single use administration to CBA-line mice and guinea pigs. The LD 50 was found to be 710 mg kg À1 for TTF and 1225 mg kg…”

“…Such an electrode can be widely used for different electrochemical applications due to a convenient potential window (from À 0.50 to þ 0.25 V vs. Ag/AgCl) [2,24]. A complex organic salt paste has already been applied to various assays, in particular, electrocatalytic oxidation of ascorbic acid (AA) [24,38,47,48], catechol [23], b-NADH [50,51], NO 2 sensing [35]; it has also been used for the development of various biosensors [7].…”

Amplification of Amperometric Biosensor Responses by Electrochemical Substrate Recycling. 3. Theoretical and Experimental Study of the Phenol−Polyphenol Oxidase System Immobilized in Laponite Hydrogels and Layer-by-Layer Self-Assembled Structures

“…In view of the numerous applications of such biosensors with amplified responses, we are interested in investigating the rate-limiting steps of these kinds of device in order to improve their metrological characteristics further. Such a theoretical and kinetic analysis is a powerful approach to rationalize biosensors functioning as demonstrated by the important work already reported in the literature. − In contrast, the amplification of biosensor responses has not yet been fully considered and only few kinetic studies have been reported. − Gorton et al theoretically considered and experimentally demonstrated the various rate-limiting steps involved for tyrosinase-modified electrodes of various configurations in the presence of catechol substrate. This model was developed for a very thin enzyme layer, and internal diffusional constraints were not considered.…”

Development of a bienzymic graphite–Teflon composite electrode for the determination of hypoxanthine in fish

“…2,3 Hence the determination of Hx is usually carried out in the course of the analysis of fish and fish products. 4 Most of the methods used for the determination of Hx are based on the enzymic reaction of the Hx oxidation catalysed by xanthine oxidase (XOD), and different biosensors have been developed for this application [5][6][7][8][9][10][11][12][13] and for the determination of the freshness index in fish. [14][15][16][17][18][19] We have demonstrated recently that graphite-Teflon composite enzyme electrodes, constructed by simple physical inclusion of the enzyme in the bulk of a graphite-Teflon pellet with no need for covalent attachments, constitute robust and practicable amperometric biosensors under both batch and flow-through conditions.…”