Chemistry Reference
In-Depth Information
an ideal platform for the development of magnetic resonance-
enhancing hybrid materials due to their high surface areas, tunable
pore structure, rigid structure, larger pore volume, great surface-
modification capability, and good biocompatibility.
3+
-dye@mesoporous
silica nanorods (MSN-R) for multifunctional cell imaging [59]. Dye@
MSN-R nanoparticles were first synthesized in the presence of the
surfactant cetyltrimethylammonium bromide (CTAB). After the
removal of the surfactant, the nanorods reacted with GdCl
Tsai
et al
. fabricated paragmagnetic Gd
O to
form the multifunctional nanorods Gd-Dye@ MSN-R. The nanorods
displayed relaxivities with
·6H
3
2
−1
−1
−1
−1
at
0.47 T, which were about five and ten times higher than the values
of the complex [Gd(DTPA)]
r
= 22 mM
s
and
r
= 41 mM
s
1
2
2−
ratio suggested that Gd-
dye@ MSN-R served as a good dual-contrast agent for both
.
The low
r
:
r
2
1
T
- and
1
T
T2-weighted MRI. Cell viability and cell function were performed to
examine its function as a cell marker, and there was no adverse effect
on cell viability. High nanorod uptake by the cells was observed
without the use of any transfection agent.
2
. reported another type of mesoporous silica
nanoparticles as a delivery system of gadolinium for effective human
stem cell tracking [60]. Gd-fluorescein isothiocyanate mesoporous
silica nanoparticles (Gd-Dye@MSN) possessed both green
fluorescence and paramagnetism. Human mesenchymal stem cells
(hMSCs) were labeled with Gd-Dye@MSN via endocytosis. An MRI
was undertaken by a clinical 1.5 T MRI system, and a low incubation
dosage of Gd, low detection cell numbers, and short incubation
times were demonstrated on both loaded cells and hMSC-injected
mouse brain. The result indicated that MSN may be an ideal vector
of
Hsiao
et al
agent for stem cell tracking with MRI. In another example, a
different Gd-Si-DTTA complex was grafted onto MSNs via siloxane
linkage [61]. The magnetic resonance relaxivities of the particles
were measured using both 3.0 T and 9.4 T magnetic resonance
scanners. On a per millimolar Gd basis, the particles showed
T
1
r
values
1
−1
−1
−1
−1
of 28.8 mM
s
at 3 T and 10.2 mM
s
at 9.4 T, while
r
relaxivities
2
−1
−1
−1
−1
were 65.5 mM
at 9.4 T, respectively.
They attributed the relative larger relaxivities to the ready access of
water molecules through the nanochannels of the MSN-Gd particles.
Their utility as contrast agent for optical imaging and MRI were also
demonstrated
s
at 3 T and 110.8 mM
s
in vitro
. MSN-Gd showed a highly efficient
T
contrast
1
