Surface decoration of functionalized carbon black nanoparticles with nanosized gold particles for electrochemical sensing of diuretic spironolactone in patient plasma

Spironolactone (SPL) is the most important drug of antimineralocorticods group that is widely used in the treatment of primary aldosteronism. Hence, the quantification of SPL in the human plasma of patients needs to be controlled more strictly. To investigate this critical point, we constructed a novel electrochemical sensor based on anchoring nanosized gold particles (AuNPs) on functionalized carbon black nanoparticles (FCBN) for SPL detection. The resulting [email protected] paste electrode ([email protected]) has an enriched electroactive surface area, a high standard heterogeneous rate constant (ket), and a small charge resistance (Rct) as compared with the bare FCBN-PE, which authenticates its good catalytic activity. The unique surface chemistry of the developed sensor allowed the ultrasensitive and selective detection of SPL with a linear range of 12–1200 nM, a low limit of detection (3.34 nM), and high sensitivity (92.7 μA μM−1 cm−2). Furthermore, electrosensing of steroidal diuretic SPL in the presence of loop diuretic torasemide (TRM) was explored, and simultaneous detection of the two diuretics was achieved. The fabricated sensor is proved to be highly reliable for the detection of SPL in tablets, human fluids, and patient plasma. The results obtained were compared with UHPLC analysis to prove the reliability of the proposed method using the designed sensor.