ZnO nanoparticle and multiwalled carbon nanotubes for glucose oxidase direct electron transfer and electrocatalytic activity investigation

A new amperometric enzyme biosensor for the determination of glucose has been constructed. Firstly, multiwalled carbon nanotubes (MWCNTs) were modified on the surface of a glassy carbon electrode (GCE). Then, the first layer of glucose oxidase (GOx) was assembled onto it. Subsequently, ZnO nanoparticles (nano-ZnO) were electrodeposited onto the electrode to immobilize the second layer of GOx. The assembly processes were characterized with cyclic voltammetry (CV), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The direct electron transfer (DET) of immobilized GOx displays a pair of well defined and nearly reversible redox peaks with a formal potential (E0′) of −0.434 V in pH 7.0 phosphate buffer solution. The electrochemical parameters including apparent heterogeneous electron transfer rate constant (ks), charge transfer coefficient (α) and surface coverage (Γ) were estimated. The proposed enzyme biosensor showed a rapid and highly sensitive amperometric response to glucose in the range of 6.67 μM to 1.29 mM with a detection limit of 2.22 μM (S/N = 3). The apparent Michaelis–Menten constant (KMapp) was calculated to be 2.48 mM. Furthermore, the biosensor showed an acceptable stability and reproducibility.

MWCNTs and nano-ZnO were applied to construct a new amperometric enzyme biosensor for the determination of glucose. The MWCNTs and ZnO/GOx/MWCNTs modified films were investigated by SEM.Figure optionsDownload as PowerPoint slideHighlights
► Double layers of glucose oxidase have been immobilized onto the electrode by using ZnO nanoparticle and multi-walled carbon nanotubes.
► Electrocatalytic activity of the direct electron transfer of glucose oxidase was investigated.
► SEM and AFM are employed in the research.
► Compare the performance of the biosensor with other glucose biosensors.