Influence of the immobilization procedures on the electroanalytical performances of Trametes versicolor laccase based bioelectrode

In this work three different immobilization methods (physico-chemical, electrostatic and covalent) of fungal laccase from Trametes versicolor (TvL) on multi-walled carbon nanotubes electrodes (MWCNTs) have been characterized and compared. To this aim, in particular, the following immobilization agents were used: polyazetidine prepolymer (PAP), Nafion solution and succinimide-carbodiimide (EDC-NHS). The comparison of these procedures has been realized by evaluating the enzymatic activity of the resulting bioelectrodes and their catalytic efficiency for oxygen reduction in the presence of the 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS) as non-phenolic redox mediator and catechol as phenolic one. Another aspect taken into account was the diffusion evaluation of several mediators as ABTS, dopamine, catechol and caffeic acid across the immobilizing layer at the pH range where the enzyme shows the maximum activity. The experimental results put in evidence the better performances of TvL-PAP-MWCNTs biosensor in terms of bioelectrochemical and diffusion properties, allowing us to asses that PAP is the best immobilizing agent thanks to its good permeability to mediators and the ability to keep the enzyme bioelectrochemical properties. (C) 2011 Elsevier B.V. All rights reserved.