MEASUREMENT OF GLUCOSE USING FLUORESCENCE QUENCHING

A new spectroscopic procedure for the measurement of glucose concentra tions is described which is based on substrate induced quenching (SIQ) of an indicator florescence. The method exploits a novel photo reacti on between thionine and NADH, the latter being generated due to the re duction of NAD+ in an enzymic reaction between glucose dehydrogenase ( GDH) and glucose. The observed SIQ data was analysed using an empirica l relation. A quenching constant of 1.8x10(3) (+/-100) M-1 is obtained for the substrate induced quenching of thionine by glucose. The repor ted method, which was investigated over the range 0-1000 muM, offers a glucose detection limit of 2.2 muM. Various applications of the propo sed scheme are discussed, including its use to construct a fibre optic biosensor for glucose.