Development of a highly sensitive electrochemical sensor for dexamethasone detection using Fe3O4/polyaniline-Cu(II) microspheres and hematite nanoparticles

Dexamethasone, a potent synthetic glucocorticoid, is widely used for its anti-inflammatory and immunosuppressive properties. However, its misuse as a performance-enhancing drug in sports has raised concerns among regulatory authorities. To address this issue, an electrochemical sensor based on Fe 3 O 4 /polyaniline (PANI)-Cu(II) microspheres and hematite nanoparticles was developed for the sensitive and selective detection of dexamethasone. The sensor exhibited excellent electrocatalytic activity towards the oxidation of dexamethasone due to the synergistic effect of the high conductivity and large surface area of the Fe 3 O 4 /PANI composite microspheres, the electrocatalytic properties of the loaded copper(II) ions, and the enhanced electron transfer of the hematite nanoparticles. Under optimized conditions, the sensor showed a wide linear range of 0.05–50 μM, with a detection limit of 0.015 μM. The sensor also demonstrated good selectivity, reproducibility (RSD = 3.2 %, n = 5), and long-term stability (92 % retention after 4 weeks). Furthermore, the sensor was successfully applied for the determination of dexamethasone in spiked human serum and urine samples, with recoveries ranging from 97.5 % to 103.5 % and RSDs less than 3.5 %.