Novel FIA chemiluminescence fiber optic biosensor for urinary and blood glucose

A chemiluminescence fiber optic biosensor system coupled to FIA was developed to measure glucose in bodily fluids. Glucose oxidase was immobilized on a preactivated nylon membrane and attached to the tip of a fiber optic bundle. This enzyme acts on ß-D-glucose to produce hydrogen peroxide which was then reacted with luminol in the presence of ferricyanide to produce a light signal. The sensitivity of the biosensor was determined to be 32 ± 0.65 nV μM^-1 with a minimum detectable level of 5 μM. The addition of a glucose oxidase column with a higher enzyme loading improved the sensitivity by at least 25-fold thus permitting the measurement of the lower glucose levels found in urine. The enzyme membrane could be reused for at least 50 analyses while the glucose oxidase column could be reused for over 500 analyses without losing the original activity. Endogenous ascorbate and urate usually present in urine samples which interfere with the chemiluminescence signal were effectively retained by an upstream ion exchange column. When applied for the determination of urinary and blood glucose levels, the results obtained compared well with those of the widely accepted hexokinase assay.