Development and characterization of ss-DNA/RGO/MoS2 modified carbon paste electrode for highly sensitive detection of capecitabine

Capecitabine (CAP) is a chemotherapeutic agent used in cancer treatment, necessitating the development of sensitive and selective detection methods for its analysis in clinical samples. The present research utilized a simplified procedure for developing a novel electrochemical sensor based on a carbon paste electrode (CPE) modified with single-stranded DNA (ss-DNA), reduced graphene oxide (RGO), and molybdenum disulfide (MoS2). Unmodified (bare CPE) and modified (ss-DNA/RGO/MoS₂/CPE) electrodes were characterized by scanning electron microscopy (SEM), EDX analysis, and cyclic voltammetry (CV). Characterization data confirm the good conductivity and electrocatalytic nature with more electrochemically active sites in ss-DNA/RGO/MoS₂/CPE compared to bare CPE in the determination of CAP in real samples. Two linear ranges were obtained for CAP concentration within the ranges of 0.01–10.00 μM and 10.00–60.00 μM, with a detection limit of 0.0108 μM and a limit of quantification of 0.036 μM. The lower linear concentration range of 0.01–10.00 μM showed a sensitivity of 276.85 AM⁻¹ cm⁻², while the range of 10–60 μM had a sensitivity of 5.88 AM⁻¹ cm⁻². The performance of the modified electrode was tested in human serum samples, yielding satisfactory recovery results. The selectivity and practical ability of ss-DNA/RGO/MoS₂/CPE to determine CAP in the presence of different interfering species were investigated, demonstrating the sensor's selective, reliable, and accurate response.