Long-lifetime luminescence of lanthanide-doped gadolinium oxide nanoparticles for immunoassays

This paper reports the luminescence spectra and lifetimes of lanthanide-doped Gd2O3 nanoparticles to identify long-lifetime luminescent reporters for immunoassays. The particles were prepared by gas-phase condensation and then annealed to obtain crystalline single-phase particles. Tb3+, Dy3+, and Eu3+ provide strong emission lines at 544, 573, and 611 nm, respectively. Of these three dopants, Dy3+ was the most sensitive to concentration quenching, but retained a lifetime of 120 μs at a concentration of ∼1%.