Ultrasmall monodisperse NaYF(4):Yb(3+)/Tm(3+) nanocrystals with enhanced near-infrared to near-infrared upconversion photoluminescence.
Photoluminescent NaYF(4):Yb(3+)/Tm(3+) nanocrystals are ideally suited for in vitro and in vivo photoluminescence (PL) bioimaging due to their virtue of near-infrared to near-infrared (NIR-to-NIR) upconversion (UC); they display PL with a peak at approximately 800 nm if excited at approximately 980 nm. Here, we report the synthesis of monodisperse NaYF(4):Yb(3+)/Tm(3+) nanocrystals of ultrasmall size (7-10 nm) with high UC efficiency. The intensity of their NIR UC emission was demonstrated to increase by up to 43 times along with an increase in the relative content of Yb(3+) ions from 20 to 100%, with a corresponding decrease in the Y(3+) content from 80 to 0%. The achieved ultrasmall NaYbF(4):2% Tm(3+) nanocrystals manifest NIR PL emission, which is 3.6 times more intense than that from 25-30 nm sized NaYF(4):20% Yb(3+)/2% Tm(3+) nanocrystals, previously synthesized and used for in vitro and in vivo bioimaging. An optimization of both size and UC PL efficiency of NIR-to-NIR nanocrystals provides us with highly efficient optical imaging probes for bioapplications.
Chen
Guanying
G
Institute for Lasers, Photonics, and Biophotonics, The State University of New York at Buffalo, Buffalo, New York 14260, USA.
Ohulchanskyy
Tymish Y
TY
Kumar
Rajiv
R
Agren
Hans
H
Prasad
Prasas N
PN
D003460:Crystallization / Q000379:methods*; D005459:Fluorides / Q000138:chemical synthesis*; 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; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013499:Surface Properties; D015019:Yttrium
D046911:Macromolecular Substances; C525362:sodium yttriumtetrafluoride; D015019:Yttrium; D005459:Fluorides