A concentration of acetone in blood and urine can be used as a potential biomarker for clinical diagnosis such as diabetes mellitus type 1. In this paper, a fiber-optic biosensor exploiting consumption of nicotinamide adenine dinucleotide (NADH) was developed for determination of acetone concentration in an aqueous solution. An optical system for the biosensor was constructed with an ultraviolet-light emitting diode excitation system, a photomultiplier tube and an optical fiber probe. The biosensor was fabricated by attaching a membrane, where NADH-dependent secondary alcohol dehydrogenase (S-ADH) was immobilized to the fiber probe. Measurement of the acetone concentration was carried out by immersing the sensor probe in phosphate buffer solution, which contained a coenzyme, NADH. NADH was consumed by the enzymatic reaction with S-ADH, and the consumption was proportional to the acetone concentration. Fluorescence light emitted from NADH was then guided to the photomultiplier tube. Effect of the buffer pH and NADH concentration to the sensor performance, and the selectivity to acetone were also evaluated. As a result, the fluorescence intensity decreased as the acetone concentration increased. A relation between the change of fluorescence intensity and the acetone concentration was found from 0.2 to $50~\mu $ mol/L using decrease phenomena of NADH fluorescence for determination of the acetone concentration. The highly sensitive and selective acetone biosensor is the potential tool for diagnosis of diabetes in near future.
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