Synergic effect studies of the bi-enzymatic system laccase-peroxidase in a voltammetric biosensor for catecholamines

Several bi-enzymatic carbon paste biosensors modified with enzymes laccase from Pleurotus ostreatus fungi and peroxidase from zucchini (Cucurbita pepo) were constructed for evaluating the synergic effect of the two enzymes on the voltammetric biosensor response for various catecholamines. Initially was investigated the effect of pH from 5.0 to 7.5, temperature from 25 to 50 degrees C, initial stirring time from 30 to 150 s, scan rate from 10 to 60 mVs(-1) and potential pulse amplitude from 10 to 60 mV on the biosensor response for several catecholamines such as dopamine, adrenaline, isoprenaline and l-dopa. It was observed a biosensor signal increase employing both enzymes, indicating thus there is a synergic effect between laccase and peroxidase, verified also in spectrophotometric studies, in the determination of these catecholamines.