Optical isopropanol biosensor using NADH-dependent secondary alcohol dehydrogenase (S-ADH)

•An isopropanol (IPA) biosensor using NADH-dependent secondary alcohol dehydrogenase.•The biosensor measured IPA level according to the fluorescence intensity of NADH.•The analysis ability of IPA biosensor was confirmed by measuring of cosmetics.

Isopropanol (IPA) is an important solvent used in industrial activity often found in hospitals as antiseptic alcohol rub. Also, IPA may have the potential to be a biomarker of diabetic ketoacidosis. In this study, an optical biosensor using NADH-dependent secondary alcohol dehydrogenase (S-ADH) for IPA measurement was constructed and evaluated. An ultraviolet light emitting diode (UV-LED, λ=340 nm) was employed as the excitation light to excite nicotinamide adenine dinucleotide (NADH). A photomultiplier tube (PMT) was connected to a two-way branch optical fiber for measuring the fluorescence emitted from the NADH. S-ADH was immobilized on the membrane to catalyze IPA to acetone and reduce NAD+ to be NADH. This IPA biosensor shows highly sensitivity and selectivity, the calibration range is from 500 nmol L−1 to 1 mmol L−1. The optimization of buffer pH, temperature, and the enzyme-immobilized method were also evaluated. The detection of IPA in nail related cosmetic using our IPA biosensor was also carried out. The results showed that large amounts of IPA were used in these kinds of cosmetics. This IPA biosensor comes with the advantages of rapid reaction, good reproducibility, and wide dynamic range, and is also expected to use for clinical IPA detections in serum or other medical and health related applications.

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