Sensitive and selective silver nanoparticle-based fluorescence sensor for corticosteroid determination in pharmaceutical formulations

Glucocorticoids play a crucial role in metabolic processes and have potent anti-inflammatory and immunosuppressive properties. Hence, developing a facile, sensitive, selective, and green approach to determine corticosteroids is essential. In this study, silver nanoparticles (Ag-NPs) were synthesized via the chemical reduction of silver nitrate using sodium borohydride in distilled water without using non-environmentally friendly organic stabilizers. The synthesized Ag-NPs exhibited high stability, as evidenced by a zeta potential measuring - 36.8 mV. Also, the average particle size was determined to be 8 ± 2 nm. These Ag-NPs were then employed as a nano fluorescence probe to establish a fluorometric assay for determining prednisolone sodium phosphate (PDN) and dexamethasone sodium phosphate (DXZ). Reduction in fluorescence intensity of Ag-NPs observed at 484 nm following excitation at 242 nm exhibited quantitative quenching upon the incremental addition of the investigated drugs, with limits of detection of 0.178 µg/mL and 0.145 µg/mL for PDN and DXZ, respectively. The quenching mechanisms were examined and explained using the Stern-Volmer and Inner Filter Effect methods. The method's selectivity was also assessed by testing other corticosteroids. The proposed method is suitable for drug testing in pharmaceutical products and quality control labs. It follows ICH guidelines and has been confirmed to be safe and eco-friendly.