Binding interaction of 5-amino-2-mercaptobenzimidazole with Au-TiO₂: inhibition of switch-on fluorescence

Abstract

Gold loaded TiO₂ nanoparticles was synthesized and characterized by powder XRD, HR-TEM, and EDX analysis. The binding interaction of 5-amino-2-mercaptobenzimidazole (fluorochrome) with TiO₂ and gold loaded TiO₂ nanoparticles was discussed herein. The interaction of fluorochrome with TiO₂ and Au-TiO₂ nanoparticles has been studied by UV-visible, fluorescence, and FT-IR spectral techniques. 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 obtained when fluorochrome is binds with TiO₂ nanoparticles. This increase in fluorescence is suppressed when TiO₂ nanoparticles is loaded with gold. This is because of chemo sensing nature of the gold. The strong adsorption of fluorochrome over the surface of nano semiconductor results in the electron transfer between fluorochrome and semiconductor. Further, the binding site of semiconductor with fluorochrome has been studied theoretically by molecular electrostatic potential diagram.

Keywords:

• Fluorochrome
• gold loaded TiO₂ nanoparticles
• fluorescence
• electron transfer