Oxygen optrode for use in a fiber-optic glucose biosensor

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Abstract
An optical fiber oxygen sensor, based on the dynamic quenching of the luminescence of tris(1,10-phenanthroline)-ruthenium(II) cation by molecular oxygen, is presented. The complex is adsorbed onto silica gel, incorporated in a silicone matrix possessing a high oxygen permeability, and placed at the tip of the opical fiber. Oxygen has been monitored continuously in the 0-50 Torr range, with the detection limit being as low as 0.7 Torr. The device has been applied to the development of a fast responding and highly sensitive fiberoptic glucose biosensor based on this highly sensitive (oxygen transducer. The sensor relates oxygen consumption (as a result of enzymatic oxidation) to glucose concentration. The enzyme is immobilized on the surface of the oxygen optrode; carbon black is used as an optical isolation in order to prevent ambient light and sample fluorescence to interfere. Measurements have been performed in a flow-through cell in air-equilibrated qlucose standard solutions of pH 7.0. The Effects of enzyme immobilization procedures (including enzyme immobilization of carbon black) as to response times (around 6 min), analytical ranges (0.06-1 mM glucose), reproducibility in sensor construction, and long-term stability have been studied as well.