Département de chimie moléculaire

Two new inorganic-organic hybrid materials based on heteropolyoxometalates (POMs): (C₄H₁₀N)₆[P₂Mo₁₈O₆₂].4H₂O (P₂Mo₁₈) and (C₆H₈NO)₄[H₂P₂W₁₈O₆₂].6H₂O (P₂W₁₈) are reported as mediators for electron transfer between FAD-dependent glucose dehydrogenase (FAD-GDH) and a multiwalled carbon nanotube (MWCNT) matrix for glucose biofuel cell and biosensor applications. These polyoxometalates were chosen due to their promising redox behavior in a potential range for mediated electron transfer with the glucose oxidizing enzyme, FAD-GDH.P₂Mo₁₈ and P₂W₁₈ were immobilized on 1-pyrenemethylamine (PMA) functionalized MWCNT deposits. After immobilization of FAD-GDH, the P₂W₁₈-modified MWCNT electrode demonstrated mediated electron transfer and provided a catalytic current density of 0.34mAcm^-2 at 0.2V vs SCE with an open circuit potential (OCP) of -0.08V vs SCE. A 10-fold increase in catalytic current to 4.7mAcm^-2 at 0.2V vs SCE and a slightly lower OCP of -0.10V vs SCE was observed for an equivalent electrode modified with P₂Mo₁₈.The apparent superiority of P₂Mo₁₈ is related, at least in part, to its improved incorporation in the MWCNT matrix compared to P₂W₁₈. Both POM-modified bioanodes showed exceptional stabilities with 45% of their initial performances remaining after 15 days. The mediated electron transfer capacities of the POMs were also evaluated in a glucose sensor setup and showed very satisfying performances for glucose detection, including a sensitivity of 0.198 mAmolL^-1 cm^-2, a satisfying linear range between 1mmolL^-1 and 20mmolL^-1, and good reproducibility for the P₂Mo₁₈ electrode.