Preparation of europium-quantum dots and europium-fluorescein composite nanoparticlesavailable for ratiometric luminescent detection of metal ions

Abstract

The silica-encapsulated luminescent lanthanide nanoparticles have beendeveloped for the selective tagging of a wide range of important targets inrecent years, however, they are mainly limited to europium and terbiumcompounds. In this work, two types of europium-containing dual-luminophore silicananoparticles, silica-encapsulated CdTe quantum dots (CdTe QDs)–BHHCT–Eu3 + complex nanoparticlesand BHHCT–Eu3 + surface-bound silica-encapsulated fluorescein isothiocyanate (FITC) nanoparticles (BHHCT:4, 4′-bis(1′′, 1′′, 1′′, 2′′, 2′′, 3′′, 3′′-heptafluoro-4′′, 6′′-hexanedion-6′′-yl)chlorosulfo-o-terphenyl), were successfully prepared using a water-in-oil (W/O) reversemicroemulsion method. The results of transmission electron microscopyand luminescence spectroscopy characterizations indicate that the twotypes of nanoparticles are all monodisperse, spherical and uniform in size (∼50 nm indiameter), and have well-resolved and stable dual luminescence emission properties. The CdTe QDs–BHHCT–Eu3 + nanoparticles can be excited at 365 nm to give dual-emission peaks at 535 and 610 nm, and the FITC–BHHCT–Eu3 + nanoparticles can be excited at 335 nm to give dual-emission peaks at 515and 610 nm. The luminescence response investigations of the nanoparticlesto different metal ions indicate that the new nanoparticles can be usedas ratiometric luminescent sensing probes for the selective detection ofCu2 + andFe2 + ions, respectively. The performance of the nanoparticle probe for metal ion detection wasinvestigated.