Electrochemical detection of agomelatine using a high-performance FeZn LDH/graphene/polyaniline nanocomposite sensor for clinical and pharmaceutical analysis.

Therapeutic monitoring of agomelatine (AG), an antidepressant with significant pharmacokinetic variability, is hindered by the complexity and cost of conventional methods. This work presents a novel electrochemical sensor employing a ternary FeZn-layered double hydroxide (LDH)/graphene/polyaniline nanocomposite for sensitive AG detection in biological and pharmaceutical samples. The synergistic properties of the nanocomposite-combining catalytic activity, high conductivity, and electrochemical stability-were confirmed through XRD, FESEM-EDS, and XPS characterization. Electrochemical analysis showed a 65% reduction in charge transfer resistance and a 21-fold increase in electroactive surface area (0.576 cm2) compared with unmodified electrodes. Using square-wave voltammetry, the sensor achieved a broad linear detection range (5-140 nM), high sensitivity (950.7 nA nM-1 cm-2), and a low detection limit. It demonstrated excellent reproducibility (< 2.5% RSD) and high recoveries (96.9-102.9%) in human urine and commercial tablets, surpassing existing nanocomposite sensors. The sensor maintained performance against 100-fold excesses of common interferents (e.g., glucose, ascorbic acid, Na+, Ca2+). By overcoming key limitations in plasma compatibility and sensitivity, this FeZn LDH/graphene/polyaniline sensor offers a robust, sustainable platform for real-time AG monitoring, directly applicable in clinical diagnostics and pharmaceutical quality control.