Nonenzymatic Sweat-Based Glucose Sensing by Flower-like Au Nanostructures/Graphene Oxide

The development of a nonenzymatic glucose sensor working in real human body conditions through a noninvasive sampling approach has attracted considerable attention. Hence, this work focuses on the development of a new nonenzymatic glucose sensor based on flower-like Au nanostructures (F-AuNTs) and graphene oxide (GO) as a supporting matrix. The F-AuNTs–GO hybrid was synthesized by simple drop casting of the GO suspension onto the graphite sheet (GS) followed by electrodeposition of F-AuNTs on GO nanosheets at 3 V in a two-electrode system. The electrocatalytic activity of the F-AuNTs–GO/GS sensor toward glucose electrooxidation was initially evaluated in a 0.1 M buffer phosphate solution (pH 7.4). The fabricated electrode shows a linear range (5 nM to 5 μM), a fast response time (6 s), a low detection limit (385 nM), and high sensitivity (162,210 μA mM–1 cm–2). Furthermore, this sensor exhibits very good selectivity in the presence of interferences such as lactic acid, uric acid, NaCl, dopamine, ascorbic acid, and inorganic salts. After obtaining the desired results, a screen-printed electrode (SPE) modified by the F-AuNTs–GO hybrid was prepared for the determination of glucose concentration from artificial sweat to evaluate the noninvasive capability of the proposed sensor. The F-AuNTs–GO/SPE exhibits good behavior for glucose detection with a long linear range of 160 nM to 82 μM and 160 μM to 5 mM, a high sensitivity of 474,617 μA mM–1 cm–1, and a low detection limit of 123 μM. Therefore, the electrochemical experiments demonstrated that F-AuNTs–GO possessed the excellent ability for electrochemically catalysis of glucose oxidation in both buffer solution and artificial sweat. Finally, the capability of the fabricated electrode was successfully investigated for glucose measurement in sweat samples. The outstanding performance of the F-AuNTs–GO-based sensor can be attributed to the superior catalytic activity of the F-AuNTs well dispersing onto GO nanosheets, which provides an excellent sensing platform owing to the enhanced electrical conductivity and large surface area. This study demonstrates that the F-AuNTs–GO hybrid is a promising candidate for the detection of glucose in sensor applications.