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.
"Prakash et al. (2008) immobilized Stirre Dark chamber Sample Fiber-optic cable to detector Beads with biocomponents fixed through a membrane Probe cell Fiber-optic cable from light source Fig. 1 Schematic diagram of fiber optic probe cell for batch measurement Table 1 Advantages and challenges associated with optical biosensors Advantages over other biosensors Challenges High sensitivity and specificity Miniaturization for mass production at affordable costs Mostly label free detection (exception: Quantum dots and fluorescence based methods) Photo bleaching of marker/tag molecule and indicator wash out Isolation from electromagnetic interference Background absorption, fluorescence and Raman scattering of fiber Possibility of multiplexing by carrying signals of different wavelengths for multiparameter detection Enhancing stability of immobilized biocomponent Isolation from electromagnetic interferences Strategies to reduce long response times in mass transfer limited reactions Compact design and minimally invasive Remote monitoring in hazardous/inaccessible spots is possible J Food Sci Technol pumpkin urease in calcium alginate beads and used for detecting mercuric ions by its inhibition. A probe consisting of an alcohol dehydrogenase immobilized membrane with fiber optic spectrometer was used for measuring ethanol (Kudo et al. 2009). Zhong et al. (2011) built an enzymatic biosensor using toluene orthomono oxygenase to detect toluene. "
[Show abstract][Hide abstract] ABSTRACT: Food quality and safety is a scientific discipline describing handling, preparation and storage of food in ways that prevent food borne illness. Food serves as a growth medium for microorganisms that can be pathogenic or cause food spoilage. Therefore, it is imperative to have stringent laws and standards for the preparation, packaging and transportation of food. The conventional methods for detection of food contamination based on culturing, colony counting, chromatography and immunoassay are tedious and time consuming while biosensors have overcome some of these disadvantages. There is growing interest in biosensors due to high specificity, convenience and quick response. Optical biosensors show greater potential for the detection of pathogens, pesticide and drug residues, hygiene monitoring, heavy metals and other toxic substances in the food to check whether it is safe for consumption or not. This review focuses on optical biosensors, the recent developments in the associated instrumentation with emphasis on fiber optic and surface plasmon resonance (SPR) based biosensors for detecting a range of analytes in food samples, the major advantages and challenges associated with optical biosensors. It also briefly covers the different methods employed for the immobilization of bio-molecules used in developing biosensors.
Journal of Food Science and Technology -Mysore- 08/2012; 49(4):383-406. DOI:10.1007/s13197-011-0437-6 · 2.20 Impact Factor
"Figure 2. Schematic illustration of the fluorometric fiber-optic ethanol biosensor and the enzyme immobilization method. 30 times higher output for ethanol than that of methanol . According to the result, the fiber-optic biosensor for ethanol solution was considered to be useful for gas monitoring use. "
[Show abstract][Hide abstract] ABSTRACT: A fiber optic bio-sniffer (biochemical gas sensor) for alcohol gas monitoring with high sensitivity and high selectivity was fabricated and tested. The bio-sniffer is a gas sensor that uses molecular recognition of enzyme to improve selectivity. Usually, enzyme loses activity in the gas phase. Applying a flow-cell with a gas-intake window to the sensing probe, enzyme immobilized at the sensing region was kept in the sufficient wet condition to maintain activity. The bio-sniffer measures ethanol (EtOH) vapor by measuring fluorescence of nicotinamide adenine dinucleotide (NADH), which is produced by enzymatic reaction at the flow-cell. In order to construct a simplified system suitable for on-site applications, a high-intensity ultraviolet light emitting diode (UV-LED) was utilized as an excitation light. Owing to low power consumption comparing with previous light sources, the bio-sniffer was considered to be suitable for laptop applications such as on-site monitoring. According to the characterization, the bio-sniffer for was useful for continuous alcohol monitoring and showed high selectivity. The calibration range was 0.30-300 ppm which is suitable for evaluation of capacity to metabolize alcohol.
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