Direct electrochemistry of glucose oxidase immobilized on Au nanoparticles-functionalized 3D hierarchically ZnO nanostructures and its application to bioelectrochemical glucose sensor

Three-dimensional (3D) hierarchically ZnO nanoarchitecture with controlled morphology and dimensions was synthesized by trisodium citrate-assisted solution phase method and functionalized by Au nanoparticles (AuNPs) via in situ reduction of HAuCl₄. The as-prepared AuNPs-functionalized 3D hierarchically ZnO nanostructure (Au–ZnO nanocomposite) were used as a novel immobilization matrix for glucose oxidase (GOD) and exhibited excellent direct electron transfer properties for GOD. The AuNPs-functionalized 3D hierarchically ZnO nanostructure (Au–ZnO nanocomposite) favored the immobilization of the glucose oxidase (GOD) and the penetration of water-soluble glucose molecules, which helped efficiently catalyze the oxidation of glucose and facile direct electron transfer for GOD. The as-fabricated glucose biosensor exhibited satisfactory analytical performance with a low detection limit (0.02 mM) and an acceptable linear range from 1 to 20 mM. These results indicated that AuNPs-functionalized 3D hierarchically ZnO nanomaterial is a promising candidate material for high-performance glucose biosensors.