Incorporation of Ln-Doped LaPO(4) Nanocrystals as Luminescent Markers in Silica Nanoparticles

Lanthanide ions are promising for the labeling of silica nanoparticles with a specific luminescent fingerprint due to their sharp line emission at characteristic wavelengths. With the increasing use of silica nanoparticles in consumer products, it is important to label silica nanoparticles in order to trace the biodistribution, both in the environment and living organisms. In this work, we synthesized LaPO(4) nanocrystals (NCs) with sizes ranging from 4 to 8 nm doped with europium or cerium and terbium. After silica growth using an inverse micelle method, monodisperse silica spheres were obtained with a single LaPO(4) NC in the center. We demonstrate that the size of the silica spheres can be tuned in the 25–55 nm range by addition of small volumes of methanol during the silica growth reaction. Both the LaPO(4) core and silica nanocrystal showed sharp line emission characteristic for europium and terbium providing unique optical labels in silica nanoparticles of variable sizes. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s11671-016-1465-y) contains supplementary material, which is available to authorized users.