Enhanced electrochemical oxygen reduction-based glucose sensing using glucose oxidase on nanodendritic poly[ meso-tetrakis(2-thienyl)porphyrinato]cobalt(II)-SWNTs composite electrodes

Abstract

The direct electrochemistry of glucose oxidase immobilized on a nanodendritic poly[ meso-tetrakis(2-thienyl)porphyrinato]cobalt(II)-single walled carbon nanotube modified glassy carbon electrode (pCoTTP-SWNTs-Nafion-GOD/GCE) is reported. The immobilized GOD retained its activity and exhibited a surface controlled, reversible two-proton and two-electron transfer reaction with a fast heterogeneous electron transfer rate constant ( k s) of 1.01 s −1. The pCoTTP-SWNTs-Nafion matrix also showed an extremely low peak potential of −0.2 V vs. Ag/AgCl and strong response with respect to oxygen reduction. This forms the basis for the use of the pCoTTP-SWNTs-Nafion-GOD composite as a sensing platform for oxygen reduction-based glucose detection. The apparent Michaelis–Menten constant ( K m,app) was estimated to be as low as 0.98 mM. A linear range up to 1 mM glucose with a low detection limit of 5.33 μM (S/N = 3) and a high sensitivity of 16.57 μA mM −1 cm −2 was achieved. The biosensor also shows excellent selectivity against 0.2 mM uric acid and ascorbic acid. These results indicate that the pCoTTP-SWNTs-Nafion-GOD/GCE has potential application in sensitive and selective glucose detection.