Enhanced sensitivity electrochemical sensor for melatonin detection using Antibody-Anchored RGO and silver nanoparticles

Melatonin (MT) is a hormone regulating the sleep-wake cycle and serves as a potential biomarker for various physiological and pathological conditions. Traditional MT detection methods, such as HPLC and MS, face challenges including complex processing, low sensitivity, and the inability to provide real-time monitoring, limiting their clinical applicability. Electrochemical sensors offer advantages like simplicity, high sensitivity, and real-time detection; however, issues such as insufficient selectivity, poor stability, and limited reproducibility in complex biological matrices persist. To address these challenges, we developed an Ab-MEL/AR/ITO electrochemical sensor by integrating AgNPs@RGO (AR) composites, synthesized using a dopamine in situ reduction method, with the MEL-1A-R (B-10) antibody (Ab-MEL) as a selective molecular recognition element for MT detection. The sensor exhibited a linear response to MT concentrations ranging from 0.01 to 1000 μM, with an exceptionally low limit of detection (LOD) of 0.0016 μM. It demonstrated excellent selectivity, maintaining performance in the presence of interferents like NaCl, glucose, and dopamine, and exhibited high reproducibility and long-term stability, with only a 5.68 % decrease in response after 28 days. The sensor achieved recovery rates of 98.10 % to 106.30 % in synthetic urine, human serum, and commercial MT capsules, underscoring its robustness and precision. By addressing the limitations of conventional methods, this Ab-MEL/AR/ITO sensor provides a highly sensitive, selective, and stable platform for MT detection, offering significant potential for clinical diagnostics and biomedical research applications.