Nitrogen- and Sulfur-Co-Doped Reduced Graphene Oxide-Based Antifouling Electrochemical Sensor for the Detection of l -Tyrosine

Abstract Electrochemical sensing of l-tyrosine is challenging because its oxidation products and other biomolecules can adsorb onto the electrode surface, resulting in electrode fouling and deterioration of sensing performance. To address this limitation, nitrogen- and sulfur-co-doped reduced graphene oxide (NS-rGO) is proposed as a dual-functional antifouling and electrocatalytic platform for l-tyrosine sensing. In this work, NS-rGO was used to modify the glassy carbon electrode (GCE), and its electrochemical performance was investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The introduction of N and S heteroatoms into the rGO framework provides an electrode surface that combines enhanced electrocatalytic activity with improved resistance to non-specific surface adsorption. The NS-rGO/GCE exhibited enhanced electrocatalytic activity towards l-tyrosine and effectively suppressed fouling caused by its oxidation products. Furthermore, the modified electrode maintained a stable current response even after 120 min of exposure to bovine serum albumin (BSA), demonstrating its ability to retain its sensing performance under a protein-rich fouling environment. The limit of detection of the sensor was found to be 0.23 ± 0.02 μM, with a sensitivity of 0.457 ± 0.01 μA μM–1 cm–2 (n = 3). These findings demonstrate the significance of NS-rGO as an antifouling sensing interface that can simultaneously address electrocatalytic activity and electrode fouling, providing a promising strategy for more stable electrochemical detection of l-tyrosine in complex matrices.