Electrochemical Tryptophan Sensor Depending on the Electrodeposition of Au Nanoparticles on the Activated Glassy Carbon Electrode

Abstract

In the present work, a novel electrochemical sensor was designed for the electrochemical detection of tryptophan (Trp). With this object in our mind, the glassy carbon electrode (GCE), utilized as the working electrode for Trp detection, was first activated in 0.1 M phosphate buffer solution (pH 7.0) by means of cyclic voltammetry. Subsequently, gold (Au) nanoparticles were electrochemically deposited on the activated GCE (AGCE) electrode in 0.1 M NaNO₃ (pH 3.0). The obtained Au@AGCE was performed for the determination of Trp. After optimizing the working conditions, electrochemical performance factors of the sensor, such as linear detection range, sensitivity, limit of detection (LOD), repeatability, selectivity, and reproducibility were investigated. The sensor showed two dynamic detection ranges for Trp. The first range, with a sensitivity of 2280.79 µA µM⁻¹ cm⁻², was between 0.4–75.8 µM, and the second range, with a sensitivity of 260.1 µA µM⁻¹ cm⁻², was between 75.8–175 µM. For the repeatability, the relative standard deviation (RSD) values were found to be in the range of 0.29%–5.26%. For reproducibility, the RSD values ranged from 3.43% to 6.03%. Additionally, Trp tablets were used to determine Trp as the real sample. The results indicated that the sensor had satisfactory performance factors.