| Aug 04, 2012 |
Ultra sensitive nanobiosensors for detection of ethanol
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(Nanowerk News) A team of researchers from the University of Kurdistan (UOK), led by Dr. Abdollah Salimi, developed a glassy carbon (GC) electrode modified with a nanocomposite comprised of multi-walled carbon nanotubes which enables low concentration detection of ethanol in different environments (see paper in Talanta: "Electrocatalytic oxidation of NADH at electrogenerated NAD+ oxidation product immobilized onto multiwalled carbon nanotubes/ionic liquid nanocomposite: Application to ethanol biosensing").
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The fermentation of food products usually leads to the liberation of minute amounts of ethanol. Thus, the detection of ethanol at low levels provides a practical means for identification of food spoilage caused by food-borne pathogenic bacteria. In addition, ethanol, at low concentrations, appears as an ingredient in the composition of many pharmaceutical drugs and hence its precise measurement can serve as a criterion for quality analysis of these products.
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By preparing a platform to immobilize the electrogenerated NAD+ oxidation products (Ox-P(NAD+)) occurring at potentials as high as 1.2 V, the UOK researchers have obtained a quinone-diimine species which plays an influential role as an intermediate in the electrocatalytic oxidation of NADH. Finally, the members of the mentioned research group have appraised the ethanol sensing performance of their proposed biosensor by taking alcohol dehydrogenase (ADH) as a model enzyme.
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“The utilization of a nanocomposite constituting multi-walled carbon nanotubes and an ionic liquid furnishes a desirable platform for immobilization of the NAD+ oxidation products and allows the realization of a highly sensitive electrocatalytic system with a considerably lowered overpotential of the NADH oxidation process.” Dr. Salimi stated, highlighting the innovative features of their experimental work.
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Furthermore, the inclusion of the carbon nanotubes improves the mechanical stability of the system and accelerates the electron-transfer processes at the electrode surface thanks to the unique electronic properties of the CNTs.
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Moreover, the MWCNTs/ionic liquid nanocomposite as the platform for immobilization of the electron-transfer mediators (i.e. NAD+ oxidation products) minimizes the superficial contaminations due to its anti-fouling property and as a result, the operational and storage stability of the system is enhanced.
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