A New Electrochemical Sensor for Dopamine Detection Based on Reduced Graphene Oxide Modified with Samarium Oxide Nanoparticles

This work reports the fabrication of a novel electrochemical sensor leveraging reduced graphene oxide (rGO) modified with samarium oxide (Sm₂O₃) nanoparticles to enhance dopamine (DA) detection. The primary goal was to create a sensitive and selective platform capable of distinguishing DA in complex biological environments. The sensor was synthesized using a hydrothermal method to form rGO/Sm₂O₃ composites, followed by characterization employing scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HR-TEM) and Raman spectroscopy to confirm morphological and structural integrity. Electrochemical assessments were conducted via cyclic voltammetry and square wave voltammetry, with the latter exhibiting an optimal response characterized by a linear range from 0.5 to 20.0 μmol L^-1 and a limit of detection (LOD) of 0.030 μmol L^-1. Comparative analyses highlighted the sensor's enhanced performance over conventional materials, with a 10-fold improvement in electron transfer rate, resulting from the higher electroactive area and the inherent functional properties of Sm₂O₃. The high selectivity was confirmed by testing against common interfering substances, and the sensor demonstrated reliable DA detection in synthetic human serum, achieving recovery rates between 95.27% and 99.39%. The findings suggested that the rGO/Sm₂O₃ sensor offers a robust, low-cost, and effective solution for DA detection with potential applications in clinical diagnostics and real-time monitoring of neurotransmitter levels in complex biological systems. This advancement underscores the relevance of integrating rare-earth oxides in sensors technology to address selectivity and sensitivity challenges in neurochemical analysis.