Synthesis of ligand-free colloidally stable water dispersible brightly luminescent lanthanide-doped upconverting nanoparticles.
The synthesis using the thermal decomposition of metal trifluoroacetates is being widely used to prepare oleate-capped lanthanide-doped upconverting NaYF(4):Er(3+)/Yb(3+) nanoparticles (Ln-UCNPs). These nanoparticles have no inherent aqueous dispersibility and inconvenient postsynthesis treatments are required to render them water dispersible. Here, we have developed a novel and facile approach to obtain water-dispersible, ligand-free, brightly upconverting Ln-UCNPs. We show that the upconversion luminescence is affected by the local environment of the lanthanide ions at the surface of the Ln-UCNPs. We observe a dramatic difference of the integrated upconverted red:green emission ratio for Ln-UCNPs dispersed in toluene compared to Ln-UCNPs dispersed in water. We can enhance or deactivate the upconversion luminescence by pH and H/D isotope vibronic control over the competitive radiative and nonradiative relaxation pathways for the red and green excited states. Direct biofunctionalization of the ligand-free, water-dispersible Ln-UCNPs will enable myriad new opportunities in targeting and drug delivery applications.
Department of Chemistry and Biochemistry, Concordia University, Montreal, QC, Canada.
Nicoleta
N
Bogdan
Fiorenzo
F
Vetrone
Geoffrey A
GA
Ozin
John A
JA
Capobianco
D003102:Colloids / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D008024:Ligands; D008163:Luminescent Measurements / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods; D010316:Particle Size; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
D003102:Colloids; D008024:Ligands; D046911:Macromolecular Substances; D014867:Water