Oxidase, intrinsic fluorescence

Trettnak W., Wolfbeis O.S., A fully reversible fibre optic glucose biosensor based on the intrinsic fluorescence of glucose oxidase, Anal. Chim. Acta 1989 221 195. 

Trettnak, W., Wolfbeis, O. S., Fully Reversible Fibre-Optic Glucose Biosensor Based on the Intrinsic Fluorescence of Glucose Oxidase , AnaL Chim. Acta 221 (1989) 195-203. 

Schematic diagram of a singlefiber biosensor based on measurement of the intrinsic fluorescence of an oxidase. From [79].

Schmid et al. used the same principle to develop sensors to be incorporated into FI systems for the determination of ascorbic acid in fruit juices [38] and that of lactic acid in dairy products [39]. The membrane used in both applications consisted of decacyclene dissolved in silicone rubber that was treated similarly as the membrane in glucose sensors (Fig. 3.4.B). The oxygen optrode was coated with a sheet of carbon black as optical insulation in order to protect it from ambient light or intrinsic sample fluorescence. Ascorbic acid oxidase or lactic acid oxidase was immobilized by adsorbing it onto carbon black and cross-linking it with glutaraldehyde. The FI system automatically buffered and diluted the food samples, thereby protecting the biosensor from a low pH and interferents. 

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