posted on 2016-07-01, 00:00authored byYing Li, Yuyang Gu, Wei Yuan, Tianye Cao, Kai Li, Shiping Yang, Zhiguo Zhou, Fuyou Li
To circumvent the defects of different
bioimaging techniques, the development of multifunctional probes for
multimodality bioimaging is required. In the present study, a lanthanide-based
core–shell–shell nanocomposite NaYbF4:Tm@CaF2@NaDyF4 composed of an ∼9.5 nm NaYbF4:Tm nanocrystal as the core, ∼2 nm CaF2 as
the middle layer, and 1–2 nm NaDyF4 as the outermost
shell was designed and synthesized. Following surface modification
with the ligand, citrate acid, this nanocomposite was hydrophilic,
emitted intense upconversion luminescence (UCL), and displayed a high
X-ray computed tomography (CT) value of ∼490 Hounsfield units
(HU) and excellent r2 relaxivity of 41.1
mM–1 s–1. These results confirmed
that the introduction of a middle CaF2 layer was necessary
as a barrier to reduce cross-relaxation and the surface quenching
effect, thus enhancing the upconversion emission of Tm3+. This citrate-modified NaYbF4:Tm@CaF2@NaDyF4 nanocomposite was used as a multifunctional contrast agent
for trimodal lymphatic bioimaging with T2-weighted magnetic
resonance imaging (MRI), CT, and UCL imaging. The concept of fabricating
a core–multishell nanostructure and the introduction of a Dy3+-based host as an outer layer is a useful strategy and can
be used to develop a novel multifunctional nanoprobe for multimodality
bioimaging.