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Luminescence-based fibre optic bisensors take advantage of the great sensitivity provided by the bioluminescence and chemiluminescence reactions. The general design of such a biosensor includes an enzymatic system immobilized at the distal end of a fibre optic which catalyses a light-emitting reaction. This sensing layer was obtained by the covalent attachment of enzymes on preactivated polyamide membranes. Batchwise systems have been first developed for ATP, NADH and H202 measurements at the picomole level, using the luciferin-luciferase system, the bacterial oxidoreductase-luciferase system and the luminol-peroxidase system, respectively. To facilitate the automation of analytical procedures, the fibre optic sensor was incorporated in a flow injection analysis (FIA) system and a specially designed flow-cell was then constructed.
A more versatile sensor was developed allowing the determination of either ATP or NADH with the same fibre optic probe. For that purpose, the firefly luciferase and the bacterial bi-enzyme system were co-immobilized on the same membrane, and one bioluminescent system or the other was functioning depending on the composition of the reaction medium.
The use of coupled reactions can greatly extend the potentialities of these sensors to other analytes. This was made possible by co-immobilizing either a dehydrogenase with the bacterial oxidoreductaseluciferase system or a HzOz-generating oxidase with peroxidase. Ethanol, sorbitol and oxaloacetate have been then assayed using the suitable dehydrogenase immobilized with the bacterial bioluminescence system as well as glucose and lactate using glucose oxidase and lactate oxidase, respectively, co-immobilized with horseradish peroxidase.
Beside metabolite detections, enzyme activity measurements can be also performed and the possibility of measuring a dehydrogenase activity with the NADH fibre optic sensor was investigated with lactate dehydrogenase as a model enzyme.
To operate the enzyme-based fibre optic sensor, co-substrates of the reaction are classically supplied by the reaction medium. Another way that has been investigated for NADH measurements is to design a self-contained fibre optic sensor in which the co-reactants, FMN and decanal, are non-covalently immobilized in the vicinity of the bound enzymes and are continuously released in the sensing layer.
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between 26 and 29 May 1998. This edition was organized by the University of Las Palmas de Gran Canaria (Spain) in collaboration with the Universities of Ghent (Belgium), Tokyo (Japan) and the Complutense of Madrid (Spain). One hundred and thirty eight delegates participated in the event. There were
which has organized it in cooperation with the Universities of Antwerp (RUCA), Brussels (VUB), Leuven (KUL), and Lie `ge (ULg) and with KaHo St.-Lieven (Dept. KIHO) (Ghent). Special attention will be given to the development and application of sensitive detection techniques (luminescence, electroche