Fe3O4 nanoparticle-modified exfoliated carbon paste electrode for enhanced electrochemical detection of dopamine

Abstract

An exfoliated carbon paste electrode modified with Fe 3 O 4 (CPE/Fe) has been developed as an advanced electrochemical sensor for detecting dopamine in aqueous solutions. The structural and morphological characteristics of the modified electrode were investigated using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). A series of CPE/Fe were fabricated with varying concentrations (10–30 wt.%) of Fe 3 O 4 . Among these, the electrode containing 20 wt.% Fe 3 O 4 and exfoliated under the optimal conditions [CPE/Fe-20% (5V; 1s)], demonstrated the highest electrochemical area (0.323 cm 2 ), as evaluated using the Ferri/Ferrocyanide redox system. DPV was identified as the best electrochemical technique for dopamine detection, showing a pronounced response of 34 μA for 0.5 μM DA in phosphate-buffered saline (PBS, pH 7.0). The sensor exhibited a wide linear detection range (1–1000 μM), with a limit of detection (LOD) of 0.024 μM and a limit of quantification (LOQ) of 0.081 μM. Importantly, the sensor demonstrated excellent selectivity for dopamine, with minimal interference (%RSD) from common compounds found in biological matrices such as uric acid (±3.1%), ascorbic acid (±4.2%), alanine (±5.3%), and adenine (±9.1%). It also effectively detected dopamine (DA) in human serum, highlighting its practical applicability. The CPE/Fe-20% (5V; 1s) electrode enables precise dopamine detection with high sensitivity and stability. This fusion supports advanced applications in neuroprosthetics and brain-machine interfaces driven by intelligent feedback systems. Schematic illustration of the Fe 3 O 4 -modified carbon paste electrode used for dopamine sensing. The optimized sensor (20% Fe 3 O 4 , 5V, 1s) enables sensitive detection with a wide linear range (1–1000 μM) and low detection limit (0.024 μM). • Fe 3 O 4 nanoparticle-modified carbon paste electrode (CPE) developed for ultrasensitive dopamine detection. • Optimized composite electrode (20% Fe 3 O 4 , 5V, 1s) exhibits a high electroactive surface area of 0.323 cm 2 . • Demonstrates a wide linear detection range (1–1000 μM) with a low detection limit of 0.024 μM. • Maintains excellent selectivity in the presence of common biological interferents.