Glucose oxidase and graphene bionanocomposite bridged by ionic liquid unit for glucose biosensing application

Ionic liquid functionalized graphene (IL-graphene) composite was synthesized successfully through an epoxide ring-opening reaction between graphene oxide (GO) and amine-terminated ionic liquid (NH2-IL). The IL-graphene exhibited good electronic conductivity, stability and electrocatalytical activity towards the reduction of O2 and H2O2. Then negatively charged glucose oxidase (GOD) was immobilized onto the composite matrix simply by ionic exchange. The ionic liquid here could improve the dispersibility of graphene and provide a favorable conductive microenvironment for the immobilized GOD, thus promote its direct electron transfer at the GC electrode. This novel IL-graphene–GOD bionanocomposite could act as a biosensor towards the detection of glucose with a linear response up to 16 mM. In this report, the method for immobilizing GOD by ionic interaction is of universality and has widespread use, even in other biological systems, which brings a forceful combination between GOD and IL-graphene. Besides, the biosensor is easy to prepare, have good stability, and will have potential application in glucose detection.