A highly sensitive glucose biosensor based on a micro disk array electrode design modified with carbon quantum dots and gold nanoparticles

A miniaturised biosensor for glucose was prepared by immobilizing glucose oxidase (GOx) onto a carbon quantum dots (CQDs)-gold nanoparticles (AuNPs) nanohybrid material which was in turn attached to gold micro disk array electrodes. The gold micro disk array electrodes (GDAE) were microfabricated on Si substrate using electronics-standard lithography, deposition and etching techniques. Each microelectrode consisted of 85 gold disk electrodes with 20 μm diameter and 200 μm inter-electrode distance and were located hexagonally. The electrodes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and cyclic voltammetry (CV). CV of the bare electrodes showed a symmetrical sigmoidal voltammogram arising from their radial diffusion profile. The electrodes developed were used to fabricate a miniaturised glucose biosensor. The resulting biosensor exhibited a high sensitivity of 626.06 μA mM⁻¹ cm⁻² towards glucose detection with excellent reproducibility and reusability. The superior performance of the biosensor is discussed in relation to the use of the micron-sized low density disk array electrodes.