Transient phase calibration of tyrosinase-based carbaryl biosensor

The inhibition of tyrosinase, used as a selective compound in amperometric biosensor for the detection of carbaryl and the possibilities of calibration of carbaryl biosensor have been studied. The kinetic analysis of biosensor data was based on the application of the biosensor dynamic model, allowing a quick calculation of independent on each other kinetic and steady-state parameters. It was found that carbaryl acts as an inhibiting substrate of tyrosinase and at low concentrations accelerates the tyrosinase-catalyzed oxidation of tyrosine by dissolved oxygen. The reaction mechanism is analogous to that usually considered for uncompetitive inhibition and the plot of kinetic parameter as a function of carbaryl concentration has a flat asymmetric maximum. Consequently, the kinetic parameter alone is not sufficient for the calibration of carbaryl biosensor and simultaneous application of other carbaryl-dependent parameters, like steady-state parameter, is essential.