Cofactor optical sensor

Xiao, Y., Pavlov, V., Levine, S., Niazov, T., Markovich, G., and Willner, I., Catalytic growth of Au-nanoparticles by NAD(P)H cofactors optical sensors for NAD(P) -dependent biocatalyzed transformations, Angew. Chem. Int. Ed., 43, 4519M 522, 2004. 

Gautier S.M., Blum L.J., Coulet P.R., Cofactor-containing bioluminescent fiber-optic sensor new developments with poly(vinyl) alcohol matrices, Anal. Chim. Acta, 1991 255 253-258. 

The creation of an optical sensor that detects the cofactors on which many enzymes dqiend is a much massociated with many enzymes, particularly dehydrogenases. This cofactor has a maximal absorption at 340 nm and a maximal fluorescence emission at 400 nm, which is easily detectable with a photomultiplier. NADH also has the advantage that it can be immobilized on the same support as the enzyme (see 3.3.1.e). nber-optic biosensors based on the fluorimetric detection of NADH have been constructed for the determination of lactate and pyruvate [208]. These sensors use inunobilized lactate dehydrogenase AD) to catalyse the following equilibrium reaction ... 

Anions play key roles in chemical and biological processes. Many anions act as nucleophiles, bases, redox agents or phase transfer catalysts. Most enzymes bind anions as either substrates or cofactors. The chloride ion is of special interest because it is crucial in several phases of human biology and in disease regulation. Moreover, it is of great interest to detect anionic pollutants such as nitrates and phosphates in ground water. Design of selective anion molecular sensors with optical or electrochemical detection is thus of major interest, however it has received much less attention than molecular sensors for cations. 

Enzyme sensors can measure analytes that are the substrates of enzymatic reactions. Thermometric sensors can measure the heat produced by the enzyme reaction [31], while optical or electrochemical transducers measure a product produced or cofactor consumed in the reaction. For example, several urea sensors are based on the hydrolysis of urea by urease producing ammonia, which can be detected by an ammonium ion-selective ISE or ISFET [48] or a conductometric device [49]. Amperometric enzyme sensors are based on the measurement of an electroactive product or cofactor [50] an example is the glucose oxidase-based sensor for glucose, the most commercially successful biosensor. Enzymes are incorporated in amperometric sensors in functionalised monolayers [51], entrapped in polymers [52], carbon pastes [53] or zeolites [54]. Other catalytic biological systems such as micro-organisms, abzymes, organelles and tissue slices have also been combined with electrochemical transducers. 

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