Glucose determination by means of steady-state and time-course UV fluorescence in free or immobilized glucose oxidase

Changes in steady-state UV fluorescence emission from free or immobilized glucose oxidase have been investigated as a function of glucose concentration. Immobilized GOD has been obtained by entrapment into a gelatine membrane. Changes in steady-state UV fluorescence have been quantitatively characterized by means of optokinetic parameters and their values have been compared with those previously obtained for FAD fluorescence in the visible range. The results confirmed that greater calibration ranges are obtained from UV signals both for free and immobilized GOD in respect to those obtained under visible fluorescence excitation. An alternative method to the use UV fluorescence for glucose determination has been investigated by using time course measurements for monitoring the differential fluorescence of the redox forms of the FAD in GOD. Also in this case quantitative analysis have been carried out and a comparison with different experimental configurations has been performed. Time coarse measurements could be particularly useful for glucose monitoring in complex biological fluids in which the intrinsic UV fluorescence of GOD could be not specific by considering the presence of numerous proteins.