Dual emissive nanoprobe for reliable detection of antipsychotic drug fluphenazine using silicon nanoparticles and eosin dye

Fluphenazine (FLU) is a widely used antipsychotic drug associated with significant extrapyramidal side effects, including dystonia, akathisia, and Parkinsonism. As such, the development of innovative and reliable sensors for its precise determination is of critical importance. In this study, a robust ratiometric fluorescent sensor was designed for accurate sensing of FLU. The probe utilizes a combination of fluorescent silicon nanoparticles (fSiNPs) and eosin, which exhibit dual emissions at 430 nm (blue) and 512 nm (green) upon excitation at 330 nm. The addition of FLU resulted in a significant quenching of eosin fluorescence at 512 nm, attributed to electrostatic interactions, hydrogen bonding, and π–π stacking interactions between the aromatic systems. Meanwhile, the fluorescence emission of the silicon nanoparticles (fSiNPs) at 430 nm remained unaffected, serving as a stable internal reference signal for ratiometric measurements. The fluorescence intensity ratio (F430/F512) exhibited a linear response to FLU concentrations in the range of 0–400 µM, with a calculated detection limit of 1.5 nM (S/N = 3). The fluorescent system was successfully applied for the detection of FLU in pharmaceutical tablets and human biological fluids, including serum and urine samples. The method achieved recovery rates ranging from 95.5 % to 103.7 %, with RSDs between 2.54 % and 4.03 %. The results highlight the high accuracy, precision, and reproducibility of the method for FLU quantification across diverse sample matrices. This robust performance underscores the system’s potential as a reliable analytical tool for pharmaceutical quality control and clinical diagnostics.