Enzyme sensor based on carbon nanotubes/cobalt(II) phthalocyanine and tyrosinase used in pharmaceutical analysis

A multicomponent enzyme sensor was used to evaluate phenolic compounds in plant-based pharmaceutical formulations. Multiwall carbon nanotubes were used as carbonaceous material used for the electrode construction. Cobalt phthalocyanine was used as electron mediator and tyrosinase as biocatalyst. The enzyme sensor performance was analyzed by cyclic voltammetry and amperometry in model solution of catechol and catechin. The cyclic voltammograms and the amperometric curves show an intense cathodic peak depending on the concentration of thephenolic compound. The cathodic peak was attributed to the reduction of enzymatically produced o-quinone at the enzyme sensor surface. For the model phenolics analyzed, the kinetics of the enzymatic reaction fitted into a Michaelis-Menten type kinetics, as confirmed by the h parameter close to 1 obtained from the Hill's plot. The detection limits were in the range of 1.66-6.32 mu M demonstrating good quality performances of the enzyme sensor. Pharmaceutical samples were analyzed with multi-component biocomposite enzyme sensor to evaluate its real feasibility in pharmaceutical analysis. (c) 2012 Elsevier B.V. All rights reserved.