Fully reversible fibre-optic glucose biosensor based on the intrinsic fluorescence of glucose oxidase

In a new type of glucose biosensor, the intrinsic green fluorescence of glucose oxidase (GOD) is used to provide the analytical information. It was found that the fluorescence of GOD changes during interaction with glucose. Fluorescence is excited at 450 nm and measured at ? 500 nm, which is a wavelength range that is compatible with glass and plastic fibres. The signal response is fully reversible because oxygen is a second substrate. A major feature of this sensor relies on the fact that the recognition element is identical with the transducer element.Enzyme solutions are entrapped at the fibre end within a semipermeable membrane. The change in fluorescence occurs over a small glucose concentration range (typically 1.5–2 mM), the signal at lower and higher glucose levels being unaffected by changes in glucose concentration. Response times of 2–30 min and regeneration times of 1–10 min are observed. Effects of pH and oxygen concentrations are also investigated. To achieve as extended analytical range (e.g., 2.5–10 mM) and shorter response times, kinetic measurements are suggested.