Electrochemically Engineered Gold Nanostructures for Selective Detection of Glucose and Ascorbic Acid

This study reports the development and characterization of modified screen-printed carbon electrodes (SPCE) for the non-enzymatic simultaneous detection of glucose and ascorbic acid. The electrodes were modified with gold nanoparticles (AuNPs) using a cyclic voltammetry electrodeposition process. The morphological and topographical evolution of the AuNPs layer was systematically investigated for 5, 10, and 15 deposition cycles using scanning electron microscopy and confocal microscopy. The key contribution of this work lies in correlating the electrodeposition-driven morphological evolution of gold nanostructures with analyte-specific oxidation behavior and electrochemical signal discrimination under mutual interference conditions. The electrochemical performance of the SPCE/15AuNPs electrode was evaluated showing an enhanced electrochemically active surface area of 1.154 mm². The optimized platform demonstrated excellent electrocatalytic activity towards the oxidation of glucose and ascorbic acid in individual and mixed solutions. Analytical validation in a 0.1 M NaOH/PBS matrix showed that the sensor maintains high selectivity and sensitivity even in the presence of significant interference. For glucose detection in a 10 mM ascorbic acid background, the sensor exhibited a linear range of 0.1–10 mM with a sensitivity of 0.03 mA/mM and a limit of detection (LOD) of 1.46 mM. Conversely, for ascorbic acid detection in a 10 mM glucose background, a linear response was obtained from 0.1 to 7 mM with a sensitivity of 0.02 mA/mM and an LOD of 1.02 mM. Interference studies with urea, sucrose, and histidine further confirmed the robust selectivity of the hierarchical AuNP surface. These results suggest that the developed SPCE/15AuNPs electrode is a promising, low-cost tool for multi-analyte sensing in complex biological fluids.