Direct electron transfer of glucose oxidase and dual hydrogen peroxide and glucose detection based on water-dispersible carbon nanotubes derivative

A water-dispersible multi-walled carbon nanotubes (MWCNTs) derivative, MWCNTs-1-one-dihydroxypyridine (MWCNTs-Py) was synthesis via Friedel-Crafts chemical acylation. Raman spectra demonstrated the conjugated level of MWCNTs-Py was retained after this chemical modification. MWCNTs-Py showed dual hydrogen peroxide (H₂O₂) and glucose detections without mutual interference by adjusting pH value. It was sensitive to H₂O₂ in acidic solution and displayed the high performances of sensitivity, linear range, response time and stability; meanwhile it did not respond to H₂O₂ in neutral solution. In addition, this positively charged MWCNTs-Py could adsorb glucose oxidase (GOD) by electrostatic attraction. MWCNTs-Py-GOD/GC electrode showed the direct electron transfer (DET) of GOD with a pair of well-defined redox peaks, attesting the bioactivity of GOD was retained due to the non-destroyed immobilization. The high surface coverage of active GOD (3.5×10^-9molcm^-2) resulted in exhibiting a good electrocatalytic activity toward glucose. This glucose sensor showed high sensitivity (68.1μAmM^-1cm^-2) in a linear range from 3μM to 7mM in neutral buffer solution. The proposed sensor could distinguish H₂O₂ and glucose, thus owning high selectivity and reliability.