The construction of molecularly imprinted electrochemical biosensor for selective glucose sensing based on the synergistic enzyme-enzyme mimic catalytic system

It is generally accepted that glucose oxidase (GOx) shows unique specificity in β-d-glucose catalysis. However, it has been found that GOx can catalyze diverse monosaccharides. Therefore, the sensing accuracy for glucose biosensors using GOx as probes will be largely compromised by the presence of other monosaccharides. Herein, multifunctional bi-nanospheres (Fe3O4@Au NCs), which show both peroxidase-like and catalase-like catalytic activities in different working conditions, are successfully constructed and served as desirable platform with huge surface area for the immobilization of large amount of GOx probes. In acidic environment, hydroxyl radicals could be generated via the cascaded catalysis of β-d-glucose by Fe3O4@Au-GOx, and then employed to initiate the polymerization of boric acid derivative to prepare molecularly imprinted polymers (MIPs) on the surface of GOx using β-d-glucose as template. Then, the molecularly imprinted GOx are immobilized on the surface of highly oriented pyrolytic graphite (HOPG) electrode and an electrochemical biosensor (Fe3O4@Au-GOx-HOPG) for glucose sensing is successfully obtained. Interestingly, the as-prepared biosensors could selectively detect glucose in the range of 10.0 μM - 5.0 mM with a LOD = 5.0 μM with the help of MIPs, which is comparable or better than other glucose sensors reported recently.