A NADH-dependent fiber-optic biosensor for ethanol determination with a UV-LED excitation system
ABSTRACT A fluorometric fiber-optic biosensor for ethanol determination was constructed and tested. An ultraviolet light emitting diode (UV-LED) was used as a fluorescence excitation source for nicotinamide adenine dinucleotide (NADH). The use of a UV-LED conferred the advantages of low power consumptions and the potential for portable application. The biosensor consists of a UV-LED based portable excitation system (λ = 340 nm), fiber optic spectrometer and an optical fiber probe with an alcohol dehydrogenase immobilized membrane. These instruments were connected using a Y-shaped optical fiber assembly. According to the experimental assessment, the power consumption was reduced to one percent of general UV light source. The measurement system was useful for 1.00–300 μmol L−1 of NADH. EtOH measurement test was also carried out. The wide calibration range of the EtOH biosensor was 0.10–100.00 mmol L−1, with high selectivity versus other chemical substances. The biosensing system is simplified and miniaturized by use of LED in compare with previous methods. For this advantage, the biosensing system is expected to be used for point-of-care testing applications or daily health care tests.
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ABSTRACT: A new amperometric biosensor for ethanol monitoring has been developed and optimised. The biosensor uses poly(neutral red) (PNR), as redox mediator, which is electropolymerised on carbon film electrodes and alcohol oxidase (AlcOx) from Hansenula polymorpha as recognition element, immobilised by cross-linking with glutaraldehyde (GA) in the presence of bovine serum albumin (BSA) as carrier protein. Optimisation of variables affecting the system was performed and, for chronoamperometric measurements, a potential of -0.300 V versus saturated calomel electrode was chosen in 0.1M sodium phosphate buffer saline at pH 7.5. The optimised biosensor showed a good sensitivity of 171.8+/-14.8nAmM(-1) and the corresponding detection limit (signal-to-noise-ratio=3) of 29.7+/-1.5 microM. Stability studies showed a good preservation of the bioanalytical properties of the sensor, 57.6% of its initial sensitivity remaining after 3 weeks (the sensor was used two to three times per week). No significant interferences were found from compounds usually present in wine. The biosensor was used for the determination of ethanol in Portuguese red and white wines.Talanta 03/2008; 74(5):1505-10. · 3.50 Impact Factor
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ABSTRACT: We have investigated highly selective and ultrasensitive biosensors based on luminescent enzyme systems linked to optical transducers. A fibre-optic sensor with immobilized enzymes was designed; the solid-phase bioreagent was maintained in close contact contact with the tip of a glass fibre bundle connected to the photomultiplier tube of a luminometer. A bacterial luminescence fibre-optic sensor was used for the microdetermination of NADH. Various NAD(P)-dependent enzymes, sorbitol dehydrogenase, alcohol dehydrogenase and malate dehydrogenase, were co-immobilized on preactivated polyamide membranes with the bacterial system and used for the microdetermination of sorbitol, ethanol and oxaloacetate at the nanomolar level with a good precision.Journal of Bioluminescence and Chemiluminescence 01/1990; 5(1):57-63.
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ABSTRACT: Using low defect density n+-Al0.4Ga0.6N buffer layers we fabricated AlGaN p-n junction light emitting diodes over sapphire substrates with peak emission at 285 nm. Powers as high as 0.15 mW were measured at 400 mA pulse pumping.Japanese Journal of Applied Physics 01/2002; 41. · 1.07 Impact Factor