Biosensors specificity

Many different polymer matrices have been reported in the literature. The use of polyvinyl alcohol (PVA) as a matrix has been reported in the construction of a biosensor specific toNADH.(71) A detailed summary of the polymerization of PVA and the attachment of fluorescein to this polymer was reported by Seitz. 22 Plasticized polyvinyl chloride (PVC) has been used for the detection of lead. 72 PVC was also... 

The developed biosensor should be, in principle, applicable to any sample suspicious of containing microcystins. This includes water samples, cyanobacterial cells and infected organisms. Whereas water samples could be directly applied to the biosensor, specific extraction protocols are required for the detection of the toxin in cyanobacteria and other organisms. In all the cases, matrix effects should be evaluated. 

Microbial biosensors have been developed based on key hydrocarbon degradation pathways. These biosensors can be used as tools to examine the regulation of the degradation pathways. In addition to the use of empirically derived data from laboratory studies, a selective meta-analysis of published data from literature sources using catabolic hydrocarbon biosensors was conducted. The aim of this work was to demonstrate that biosensor specific QSARs may be developed to first assess the specificity of degradation pathways and then to assess the possibility of predicting analyte-specific degradation characteristics. 

Biosensors are being increasingly used as detectors in FIA systems [284,285, 322, 379, 476]. The drawbacks of biosensors as direct in situ sensors, namely their low dynamic range, their lack of ability to survive sterilization, their limited lifetime, etc. are no longer valid ex situ because the analyzer interfaces the biosensor which can be changed at any time and FIA can provide samples in optimal dilution. The need for chemicals and reagents can be drastically reduced when employing biosensors, specifically when the entire system is miniaturized [48]. 

In the future, spiropyrans most likely will be used chiefly in biochemistry and image technology or optical physics, in ways in which their inherent fatigue can be neglected (not overcome - merely neglected). The potential applications of properly designed spiropyrans as biosensors specific for cations and nucleotides has already been described. 

Korpan YI, Gonchar MV, Starodub NF, et al. 1993. A cell biosensor specific for formaldehyde based on pH-sensitive transistors coupled to methylotrophic yeast cells with genetically adjusted metabolism. Anal Biochem 215 216-222. 

To make the biosensor specific for an analyte, a membrane is generally used that contains a recognition layer trapping the specific enzyme that catalyses the... 

In any case the stabilization of the biosensor specification is of outstanding importance. Not only enzyme stabihty but also the reaction products of enzymatic processes have to be taken into account because they will be enriched at the location of enzymes, can change pH and also attack the microenvironment of the enzymes chemically. Therefore, diffusion and permeation of these products are very important to deal with (Bakker 2004 Asberg and Inganas 2003). First priority is given in any way to stabilize enzymes in an appropriate matrix. Here the thermodynamic stability of enzymes in a hydrogel has to be taken into consideration. 

The goal of the present review is an analysis of the electrochemical sensor approaches used for the detection of hydrogen peroxide. Due to similarity of the subjects the present review discusses both, the development of the biosensors where hydrogen peroxide is a product/substrate of enzynutic reaction and also the development of chemical sensors/biosensors specifically designed for the detection of this analyte. Several rechnical aspects of the development of sensors for hydrogen peroxide are reviewed in the following chapters the choice of physical transducer, the choice of enzyme and immobilisation method, and the performance of sensors with respect to response time, sensitivity, linear range, detection limit and operational stability. 

Table 18. Biosensor specification according to the nature of the primary sensing reaction (356)...

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). 

Entrapment of biochemically reactive molecules into conductive polymer substrates is being used to develop electrochemical biosensors (212). This has proven especially useful for the incorporation of enzymes that retain their specific chemical reactivity. Electropolymerization of pyrrole in an aqueous solution containing glucose oxidase (GO) leads to a polypyrrole in which the GO enzyme is co-deposited with the polymer. These polymer-entrapped GO electrodes have been used as glucose sensors. A direct relationship is seen between the electrode response and the glucose concentration in the solution which was analyzed with a typical measurement taking between 20 to 40 s. 

The work presented is part of a European project (Biosensors for Effective Environmental Protection BEEP) which is aimed at the assembly and application of Photosystem II (PS II)-based biosensors for large scale environmental screening of specific herbicides and heavy metals. 

Biosensor An electronic device that transforms signals produced by biological molecules to detect concentration or transport of specific compounds. 

Electrochemical biosensors combine die analytical power of electrochemical techniques with the specificity of biological recognition processes. The aim is to... 

Sequence-specific biosensor, 183, 185 Selectivity, 92, 143, 147, 155 Selectivity coefficient, 143 Self-assembled monolayers, 39, 118 Selenium, 85 Sensor, 171 Silver halide, 159 Simulation, 35... 

There are also RMs which are prepared for a specific application and are used for validation of relevant methods. Cobbaert et al. (1999) made use of Ion Selective Electrode (ISE)-protein-based materials when evaluating a procedure which used an electrode with an enzyme-linked biosensor to determine glucose and lactate in blood. Chance et al. (1999) are involved with the diagnosis of inherited disorders in newborn children and they prepared a series of reference materials consisting of blood spotted onto filter paper and dried, from which amino-acids can be eluted and... 

It is critical to keep in mind that existing reagents can be used for multiple formats. Eor example, polyclonal antibodies dominate the environmental field because they generally provide greater sensitivity and specificity for small molecules at a much lower cost than do monoclonal or recombinant antibodies. With some biosensors monoclonal or engineered antibodies or recombinant binding proteins may offer advantages. 

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