Down-/up-conversion luminescence nanocomposites for dual-modal cell imaging.

Dual-modal luminescence nanocomposites (NCs) were successfully prepared via a facile and versatile strategy by embedding the hydrophobic down-conversion (DC) fluorescence ZnS:Mn2+ quantum dots (QDs) and up-conversion (UC) luminescence NaYF4:Er3+/Yb3+ nanoparticles (NPs) into hydrophilic polymer matrixes through in situ cross-linking polymerization. Due to the enriched carboxylic groups in the polymer matrixes, the as-prepared NCs are highly water-stable and bioconjugatable with chemical and biological moieties. The results of cytotoxicity assay and dual-modal luminescence cell imaging application of DC-UC NCs indicate that the as-prepared NCs are biocompatible and applicable in biomedical fields. The current work paves the way to the fabrication of multifunctional NCs including down- and up-conversion dual-modal luminescence, luminescence-magnetism, magnetic targeted drug vehicles and magnetic recyclable catalyst NCs, and will attract wide attention from the fields of chemistry, materials, catalysis, nanotechnology, nanobiotechnology and nanomedicine.