Utility of Microwave-Synthesized Silver Nano Particles as Spectrofluorimetric Sensors for the Determination of Nano Concentrations of Favipravir: Application to Dosage Forms and Spiked Human Plasma

A simple and facile microwave-assisted method was developed for the synthesis of highly fluorescent silver-nanoparticles (Ag-NPs). The synthesis of silver-nanoparticles depends on a redox reaction between silver nitrate and ascorbic acid using chitosan as a stabilizing agent. The produced Ag-NPs were characterized using Zeta potential and transmission electron microscope micrograph where they are spherical in shape with smooth surface morphology and size of 26.81 ± 2.2 nm. Favipiravir (FAV) was found to cause an obvious enhancement in the fluorescence of Ag-NPs; hence, they were used for its spectrofluorimetric estimation. The fluorescence intensity was measured at 430 nm after excitation at 360 nm. Under optimum conditions, a good linear relationship was accomplished between the FAV concentration and the fluorescence intensity in a range of (5.0–200.0) ng/mL with a limit of detection of 1.59 ng/mL. The method was successfully applied for the assay of the drug in its commercial tablets and spiked human plasma samples, and the results obtained were satisfactory.