Near-infrared to visible and near-infrared upconversion of monoclinic Gd2O3:Yb3+/Tm3+ nanoparticles prepared by laser ablation in liquid for fluorescence imaging

Upconversion nanoparticles (UCNPs) possess great potential for application in fluorescence imaging. Here, the high crystalline Gd2O3:Yb3+/Tm3+ UCNPs with the average diameter of 7.18 nm were fabricated by laser ablation in liquid (LAL). Under excitation at 980 nm, visible blue fluorescence of the LAL-derived Gd2O3:Yb3+/Tm3+ UCNPs is obtained and can be used for live cells imaging. Meanwhile, more efficient near-infrared (NIR) emission (∼800 nm) than the visible fluorescence is observed. The excitation and emission of Gd2O3:Yb3+/Tm3+ UCNPs are both within the “optical transmission window” of biological tissue, capable of great potential for deep tissues imaging.