The Development of Reagentless Amperometric Glucose Biosensor Based on Gold Nanostructures, Prussian Blue and Glucose...

Precise blood glucose detection plays a crucial role in diagnosing and medicating diabetes, in addition to aiding diabetic patients in effectively managing their condition. In this research, a first-generation reagentless amperometric glucose biosensor was developed by combining the graphite rod (GR) electrode modification by gold nanostructures (AuNS) and Prussian blue (PB) with glucose oxidase (GOx)-an enzyme that can oxidize glucose and produce H₂O₂. Firstly, AuNS was electrochemically deposited on the GR electrode (AuNS/GR), and then PB was electrochemically synthesized on the AuNS/GR electrode (PB/AuNS/GR). Finally, GOx was immobilized over the PB/AuNS nanocomposite with the assistance of Nafion (Nf) (Nf-GOx/PB/AuNS/GR). An application of PB in the design of a glucose biosensor enables an easy electrochemical reduction and, thus, the determination of the H₂O₂ produced during the GOx-catalyzed oxidation of glucose in the sample at a low operation potential of -0.05 V vs. Ag/AgCl/KCl_{3 mol L}^-1. In addition, AuNS increased the electrochemically active surface area, improved the GOx immobilization and ensured a higher analytical signal. The developed glucose biosensor based on the Nf-GOx/PB/AuNS/GR electrode exhibited a wide linear range, from 0.025 to 1 mmol L^-1 of glucose, with a 0.0088 mmol L^-1 limit of detection, good repeatability and high selectivity over electroactive interfering substances. The developed biosensor is convenient for the determination of glucose in the physiological environment.