Potentiometric and Spectroscopic Investigations of the Reaction of Fluorescein Isothiocyanate with an Amine Chemically Bound on Solid Surfaces

Abstract

Titanium electrode surface was chemically modified with an aminosilane. The potential of the electrode was shifted to the negative direction by a reaction of fluorescein isothiocyanate in solution with the amine on the electrode surface. The absorption and emission spectra were measured for the fluorescein isothiocyanate, fixed by the reaction with the aminosilane which was chemically bound on the surfaces of tin oxide, titanium oxide and quartz, in solutions and in air. In an alkaline solution, the absorption and emission spectra showed the band ascribable to the dianion of the fluorescein. A peak, attributable to the monoanion, was observed in both absorption and emission spectra measured for the samples kept in air. The surface coverage of the dye was estimated from the absorbances to be about 10−6 mol m−2 for both tin oxide and quartz. The bound dye fluoresced under exposure to ultraviolet light, due probably to the energy transfer from tin oxide to the dye.

Adsorption and Encapsulation of Fluorescent Probes in Nanoparticles

“…5 × 10 -7 M (for 5 × 10 -5 M Au). Above 5 × 10 -7 M of FITC, the gold plasmon absorption band undergoes no further changes, but the absorption band characteristic for FITC in alkaline solution at about 491 nm , becomes visible. Observations similar to these were reported by Kerker for the absorption spectra of silver particles coated with rhodamine B.…”