Xanthine oxidase fluorescence

Several other biosensors have been developed usiag this oxygen-quenched fluorescence approach. Target species iaclude ethanol [64-17-5] hydrogen peroxide [7722-84-17, H2O2, lactate, and xanthine [69-89-6] C H4N402, usiag alcohol oxidase, catalase [9001-05-2] lactate oxidase, and xanthine oxidase, respectively. An additional technique for biocatalytic biosensors iavolves the firefly chemiluminescent reaction (17) ... 

NADH and NADPH, the respective reduced forms of NAD and NADP, are highly fluorescent hence, all NAD" "- and NADP -dependent reactions involved in enzymatic assays can be monitored fluorimetrically with a sensitivity higher than those of absorptiometric techniques by two or three orders of magnitude. Reactants must be used at much lower concentrations, and detection limits of 10 moll or even lower can be achieved. Numerous methods for enzyme determination involve the use of substrates that are transformed into highly fluorescent products. For instance, p-hydroxyphenyl-acetic acid has been used widely as a substrate for the determination of several oxidases such as glucose oxidase and xanthine oxidase. 

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