Poly(dicarbazole-N-hydroxysuccinimide) film: A new polymer for the reagentless grafting of enzymes and redox mediators

Upon oxidative electropolymerisation of a new dicarbazole derivative functionalised by a N-hydroxysuccinimide group in acetonitrile, electroactive poly(dicarbazole) films were formed on electrodes. The subsequent chemical functionalisation of the poly(dicarbazole) film was easily performed by successive immersions in aqueous enzyme and mediator solutions. Investigations by cyclic voltammetry showed that thionine and toluidine blue o have been irreversible bound to the poly(dicarbazole) backbone. The amperometric responses of the poly(dicarbazole) films grafted with polyphenol oxidase (PPO) and thionine to catechol were then investigated at -0.2 V vs. SCE. The catechol sensitivity and the maximum current at saturating catechol concentrations were 14.57 mA M^-1cm^-2 and 15.43 μA cm^-2 respectively. The comparison of this catechol sensitivity with that of a poly(dicarbazole) film only modified with PPO (3.40 mA M^-1 cm^-2) highlighted the improvement of the biosensor performance brought by thionine as immobilised redox mediator.