Chemistry Reference
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. reported a hybrid lanthanide nanoparticle consisting of
an upconverting lanthanide-doped NaYF
Li
et al
nanocrystal core and a
Gd-based paramagnetic complex shell [79]. The uniform core-shell
structured NaYF
4
: Yb, Er@Si-DTTA (3-aminopropyl(trimethoxysilyl)
diethylenetriamine tetraacetic acid) nanoparticles were first
prepared, and Gd ions were then loaded into the nanoparticles.
The core/shell nanoparticles had strong fluorescence intensity
and remained stable in water over seven days. Magnetic resonance
relaxivities showed that the nanoparticles had
4
−1
−1
r
of 20.1 mM
s
1
−1
−1
3+
and
-ion basis. Besides,
magnetic resonance signal intensity increased along with increasing
concentration of nanoparticles in the
r
of 55.0 mM
s
on a per milimolar Gd
2
-weighted mode while signal
became weaker with increasing concentration of nanoparticles in
the
T
1
-weighted mode, which suggested that the nanoparticles may
be useful for both
T
2
T
- and
T
- weighted MRI.
1
2
5.2.1.2
SPIO-based multimodal imaging agents
Superparamagnetic
iron
oxide
nanoparticles
(SPIO)
are
MRI contrast agents. Doped with different rare
earth elements or coated with a shell of rare earth elements, the
“two-in-one” bifunctional nanoparticles are
representatives of
T
2
T
as well as fluorescent
2
contrast agents. Yu
: Ce,
Tb nanocrystals with an average diameter around 30 nm [80]. The
Fe
et al
. reported water-soluble Fe
O
@LaF
3
4
3
nanoparticles were prepared by a hydrothermal method. After
fabricating the core nanoparticles, they were further reacted with
cetyltrimethylammnoium bromide (CTAB) to attach hydrophilic
ligands to the surface of the nanoparticles, rendering them water-
soluble. The CTAB-treated Fe
O
3
4
nanoparticles were further coated
with a fluorescent lanthanide ion doped layer (LaF
O
3
4
: Ce, Tb). These
nanoparticles showed strong downconversion luminescence and
good magnetism. Zhang
3
et al
. reported single-phase Tb-doped
nanocrystals, which combined superparamagnetism and
luminescence into the same nanocrystals (Fig. 5.17a,b) [81]. The
Tb-doped γ-Fe
γ-Fe
O
2
3
nanocrystals exhibited green photoluminescence
under 235 nm excitation (Fig. 5.17c). These nanoparticles showed
minimal toxicity to the cells.
O
2
3
