Inhibition of Switch-on Fluorescence of Fluorochrome on Loading TiO2 with Gold

Abstract

Gold loaded TiO2 nanoparticles have been synthesized and characterized by powder XRD, HR-TEM, and EDX analysis. The binding interaction of fluorescent sensor 5-amino-2-mercaptobenzimidazole (fluorochrome) with TiO2 and gold loaded TiO2 nanoparticles has been discussed herein. The interaction of fluorochrome with TiO2 and gold loaded TiO2 nanoparticles has been studied by UV-visible, fluorescence, and FT-IR spectral techniques. The fluorescence emission occurs at 421 nm and this has been selectively enhanced by TiO2 nano semiconductor. This technique is sensitive to detect and estimate TiO2 nano semiconductor at a micromolar level. This switch-on fluorescence is suppressed when it is loaded with gold. The strong adsorption of fluorochrome over the surface of nano semiconductor results in the electron transfer between fluorochrome and nano semiconductor. Further, the binding site of nano semiconductor with fluorochrome has been studied theoretically by using the molecular electrostatic potential (MEP). The results show higher electron density at the azomethine nitrogen atom.