Water dispersible ultra-small multifunctional KGdF4:Tm3+, Yb3+nanoparticles with near-infrared to near-infrared upconversion

Hon Tung Wong, Fiorenzo Vetrone, Rafik Naccache, Helen Lai Wa Chan, Jianhua Hao, John A. Capobianco

Research output: Journal article publicationJournal articleAcademic researchpeer-review

147 Citations (Scopus)


Ultra-small multifunctional KGdF4:Tm3+,Yb3+nanoparticles with near-infrared to near-infrared upconversion are synthesized. The average sizes of KGdF4:Tm3+2%, Yb3+20% core-only and KGdF4:Tm3+2%, Yb3+20%/KGdF4core-shell nanoparticles are ∼3.7 nm and ∼7.4 nm, respectively, which fall within the reported optimal sizes (<10 nm) for bioimaging probes. The excitation and emission at 980 and 803 nm are favorable to deeper tissue penetration and reduced autofluorescence. The weak upconversion luminescence of the ultra-small core-only nanoparticles is overcome by the use of the core-shell approach. The magnetic mass susceptibility and magnetization of the ultra-small core-only and core-shell nanoparticles were determined, and are close to those of large nanoparticles (26 and 50 nm) used for magnetic resonance imaging and bio-separation. There is no variation in the magnetic properties with the nanoparticles' sizes between the core-only (∼3.7 nm) and core-shell (∼7.4 nm) nanoparticles, which differs from the size-dependent luminescence. The oleate-capped core-shell nanoparticles were further encapsulated with a PEG-phospholipid shell to endow them with dispersibility in water, which is indispensable for future biological applications.
Original languageEnglish
Pages (from-to)16589-16596
Number of pages8
JournalJournal of Materials Chemistry
Issue number41
Publication statusPublished - 7 Nov 2011

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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