INVESTIGATION OF THE FLUORESCENCE QUENCHING DEPENDING ON EXCITATION WAVELENGTHS OF RHODAMINE B TO QUANTIFY SILVER NANOPARTICLES VIA THE INNER FILTER EFFECT

Abstract

Silver nanoparticles (Ag NPs) with a size of around 9 nm were fabricated and quantified through fluorescence quenching of rhodamine B (RhB). A series of solutions composed of RhB with various concentrations of Ag NPs ranging from 0.09 pM to 0.98 pM were prepared, and optical properties were investigated by absorption and fluorescence spectroscopies. The fluorescence quenching of RhB was observed for the mixing solution of RhB and Ag NPs. The fluorescence measurement condition was optimized by controlling excitation wavelengths to obtain the highest efficiency of fluorescence quenching. The examination of the fluorescence quenching depending on excitation wavelengths indicated that under the excitation wavelength of 400 nm, the highest efficiency of fluorescence quenching of RhB was achieved. At this optimized condition, the lowest concentration of Ag NPs that could be quantified reaches 0.09 pM. It shows a good limitation in the detection of Ag NPs in comparison with the previous works. The mechanism of fluorescence quenching of RhB with the presence of Ag NPs has been revealed as the result of the inner filter effect.