Covalent modification of ordered mesoporous carbon with glucose oxidase for fabrication of glucose biosensor

• The electrochemistry of glucose oxidase covalently attached to ordered mesoporous carbon is investigated.
• The biosensor has response to glucose in the presence of a mediator even though the DET of enzyme is observed.
• The biosensor retains 94.3% of its initial activity after 30 days.

In this paper, a new methodology is developed for the modification of glassy carbon electrode (GCE) with covalently modified ordered mesoporous carbon (OMC) with glucose oxidase (GOD) as a model of electroactive biomolecules. In this methodology the following steps were followed: (1) preparing the OMC modified GCE (OMC/GCE) by simple casting, (2) functionalization of OMC/GCE with 4-nitrophenyl (NP) group by electrochemical reduction of 4-nitrobenzenediazonium salt in nonaqueous media, (3) converting the surface NP to aminophenyl (AP) through electrochemical reduction, (4) covalent attachment of 2,4,6-trichloro-1,3,5-triazine (TCT) to the surface of electrode through its reaction with AP and (5) enzyme immobilization through reaction between GOD and surface TCTs. The direct electrochemistry and catalytic activity of the immobilized GOD on OMC are investigated. Although the cyclic voltammetry (CV) revealed direct electron transfer (DET) between GOD and the OMC modified electrode, however, the biosensor shows response to glucose only in the presence of oxygen, indicating the DET capability and enzymatic activity occurred on different immobilized GODs. The surface coverage of GOD with DET property and GOD with enzymatic activity are 2.94 × 10−10 and 6.87 × 10−12 mol cm−2, respectively. The obtained glucose biosensor shows excellent analytical performance for glucose determination.