Functionalized Graphene Oxide Bridging between Enzyme and Au-Sputtered Screen-Printed Interface for Glucose Detection

This work reports the fabrication of an electrochemical glucose biosensor based on functionalized graphene, assembled onto a gold-sputtered screen-printed electrode. With the aim of simplicity, versatility, and low cost, biosensors dually functionalized with graphene oxide containing excess carboxylic acids and thiol functionality were synthesized and characterized by Fourier transform infrared, Raman, and UV–vis spectroscopy. The increased carboxylic groups of the graphene backbone provided more active sites for the remote functional groups of glucose oxidase during 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide-assisted immobilization. The modified electrode interface was characterized by scanning electron microscopy, atomic force microscopy, and cyclic voltammetry. This hybrid electrode interface showed higher sensitivity for glucose (3.1732 μA mM–1 cm–2) with a detection limit of 0.3194 mM (S/N = 3). Furthermore, the fabricated biosensor demonstrated a linear response in 3–9 mM glucose concentration with the correlation coefficient of 0.94693, a performance well beyond that of the similarly fabricated electrode interfaces in terms of selectivity and efficiency. The enhanced electrochemical performance is assumed to originate simultaneously from sputtered morphology of Au and the bifunctionality of the graphene backbone. This work highlights the significant potential for Au-sputtered electrode interfaces coupled with a bifunctional graphene backbone toward several biomedical applications.