Biofunctionalizable flexible bucky paper by combination of multi-walled carbon nanotubes and polynorbornene-pyrene - Application to the bioelectrocatalytic reduction of oxygen

Owing to their conductivity, carbon nanotubes (CNTs) coatings are widely used for modifying electrode surfaces. In particular, the formation of bucky papers (BP) based on CNT assemblies obtained by filtration, represents an attractive way of creating a new kind of electrode. However, these BP are brittle and difficult to manipulate, hence their applications remain limited due to their fragility and lack of flexibility. Notably, their use for “in vivo” experiments is markedly hampered by the potential release of CNTs. The strengthening of the mechanical stability of BP has hereby been explored by the combination of BP and linear polymeric chains displaying non-covalent π-interactions with CNTs. These organic polymers act as a cross-linking agent throughout the BP assembly thus conferring stability and flexibility. Flexible BP electrodes were produced by simply mixing poly(norbornene) bearing pyrene groups and multi-walled CNTs, both dispersed in dimethylformamide followed by filtration through a PTFE membrane. The immobilization of laccase as a model protein was achieved on the resulting BP electrodes by adsorption or chemical grafting. These biocathodes displayed a direct electrical communication with laccase, allowing the reduction of oxygen in water (pH 5) with maximum current densities of ca 1.1 mA cm⁻² at 0.4 V vs. SCE.