Mechanistic Investigation of Photon Upconversion in Nd~(3+)-Sensitized Core-Shell Nanoparticles

摘要

A new type of core-shell upconversion nanoparticles which can be effectively excited at 795 nm has been designed and synthesized through spatially confined doping of neodymium (Nd~(3+)) ions. The use of Nd~(3+) ions as sensitizers facilitates the energy transfer and photon upconversion of a series of lanthanide activators (Er~(3+), Tm~(3+), and Ho~(3+)) at a biocompatible excitation wavelength (795 nm) and also significantly minimizes the overheating problem associated with conventional 980 nm excitation. Importantly, the core-shell design enabled high-concentration doping of Nd~(3+) (～20 mol %) in the shell layer and thus markedly enhanced the upconversion emission from the activators, providing highly attractive luminescent biomarkers for bioimaging without autofluor-escence and concern of overheating.