Département de chimie moléculaire

Strategies to maximize direct electron transfer (DET) between redox enzymes and electrodes include the oriented immobilization of enzymes onto an electroactive surface. Here, we present a strategy for achieving a controlled orientation of a fungal laccase on carbon nanotube-based electrodes. A homogeneous population of pyrene-modified laccase is obtained via the reductive amination of a unique surface accessible lysine residue engineered near the T1 copper center of the enzyme. Immobilization of the site-specific functionalized enzyme is achieved either via $π$-stacking of pyrene on pristine CNT electrodes or through pyrene/$\beta$-cyclodextrin host guest interactions on $\beta$-cyclodextrin-modified gold nanoparticles ($\beta$-CD-AuNPs). Contrasting with unmodified and nonspecifically modified (pyrene-NHS) laccase-electrodes, an efficient DET is obtained at these nanostructured assemblies. Modeling the direct bioelectrocatalysis of dioxygen redn. reveals a heterogeneity in ET rates on MWCNT electrodes wheras $\beta$-CD-AuNPs act as efficient electronic bridges, lowering ET rate dispersion and achieving a highly efficient redn. of O2 at low overpotential (≈80 mV) accompanied by high catalytic current densities of almost 3 mA cm-2. [on SciFinder(R)]