Sensitivity enhancement in an in-vitro glucose sensor using gold nanoelectrode ensembles

Enzymatic electrochemical sensor for glucose detection is fabricated based on hydrothermally grown zinc oxide (ZnO) nanorods. The conception of gold (Au) nanoelectrode ensembles (NEEs) is applied to enhance the sensitivity of the electrochemical sensor under investigation. The characterization of as-synthesized ZnO nanorods on Au and indium tin oxide substrates is performed using X-ray diffraction, scanning electron microscopy, and micro-Raman spectroscopy. The current sensitivity of sensors with and without Au NEEs are computed using the cyclic voltammetry and amperometric tests executed for the glucose level ranging from 0.01 to 11.00 mM/L. Current sensitivity of 7.5 µA/mM for a linear range of glucose concentration from 0.01 to 6.5 mM is testified. Response time of 1 s and a low limit of detection of 0.065 mM is reported for the sensor based on Au NEEs. The need of ZnO nanorods in the sensor working electrode, to immobilize enzyme glucose oxidase is justified. The presence of Au NEEs boost the sensor current sensitivity by enhancing the rate of electron transfer during the electrochemical reaction.