Clinical biosensors

Environmental Applications Although ion-selective electrodes find use in environmental analysis, their application is not as widespread as in clinical analysis. Standard methods have been developed for the analysis of CN , F , NH3, and in water and wastewater. Except for F , however, other analytical methods are considered superior. By incorporating the ion-selective electrode into a flow cell, the continuous monitoring of wastewater streams and other flow systems is possible. Such applications are limited, however, by the electrode s response to the analyte s activity, rather than its concentration. Considerable interest has been shown in the development of biosensors for the field screening and monitoring of environmental samples for a number of priority pollutants. 

Individual polyethers exhibit varying specificities for cations. Some polyethers have found appHcation as components in ion-selective electrodes for use in clinical medicine or in laboratory studies involving transport studies or measurement of transmembrane electrical potential (4). The methyl ester of monensin [28636-21 -7] i2ls been incorporated into a membrane sHde assembly used for the assay of semm sodium (see Biosensors) (5). Studies directed toward the design of a lithium selective electrode resulted in the synthesis of a derivative of monensin lactone that is highly specific for lithium (6). 

Vol. 148. Commercial Biosensors Applications to Clinical, Bioprocess and Environmental Samples. Edited by Graham Ramsay... 

Muller C., Hitzmann B., Schubert F., Scheper T., Optical chemo- and biosensors for use in clinical applications, Sensor Actuat B-Chem. 1997 40 71-77... 

D Orazio P., Biosensors in Clinical Chemistry, Clin. Chim. Acta 2003 334 41-69. 

R D Orazio, Biosensors in clinical chemistry. Clin. Chim. Acta 334, 41-59 (2003). 

S. Brahim, D. Narinesingh, and A. Guiseppi-Elie, Polypyrrole-hydrogel composites for the construction of clinically important biosensors. Biosens. Bioelectron. 17, 53-59 (2002). 

Accurate, rapid, cheap, and selective analysis is required nowadays for clinical and industrial laboratories. Electrochemical biosensors seem to accomplish this function. 

The determination of H202 is very important in many different fields, such as in clinical, food, pharmaceutical, and environmental analyses [202], Many techniques such as spectrophotometry, chemiluminesence, fluorimetry, acoustic emission, and electrochemistry methods have been employed to determine H202. Electrochemical methods are often used because of their advantages. Among these electrochemical methods, the construction of the mediator-free enzyme-based biosensors based on the direct electrochemistry of redox proteins has been reported over the past decade [203— 204], The enzyme-based biosensors, which use cyt c as biocatalyzer to catalyze H202, were widely studied. 

In conclusion, more than 40 years after the first electrode with an immo-bilized-enzyme membrane was produced, future developments in biosensor design will inevitably focus upon the technology of new materials, especially the new copolymers that promise to solve the biocompatibility problem and offer the prospect of more widespread use of biosensors in clinical (and environmental) monitoring [80]. 

As far as the use of ferrocene molecules as amperometric sensors is concerned, they have found wide use as redox mediators in the so-called enzymatic electrodes, or biosensors. These are systems able to determine, in a simple and rapid way, the concentration of substances of clinical and physiological interest. The methodology exploits the fact that, in the presence of enzyme-catalysed reactions, the electrode currents are considerably amplified.61 Essentially it is an application of the mechanism of catalytic regeneration of the reagent following a reversible charge transfer , examined in detail in Chapter 2, Section 1.4.2.5 ... 

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