Biomedical Engineering Reference
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(a)
(b)
Fe(acac)
3
+ROH+RCOOH+RNH
2
+Ph
2
O
Heating
Size decrease
(c)
(d)
4nm
nm
9nm 2nm
25 nm
(e)
T
2
-weighted
MRI signal
High
R2
Color
mapping
2.8 nm
Low
(f)
250
200
150
100
50
0
150
100
5
50
10
15
0
fIgure 2.4
(a) Schematic illustration of size-induced surface spin-canting effect in MNPs.
(b) The synthesis of Fe
3
O
4
NPs
via
thermal decomposition of Fe(acac)
3
and (c) the HRTEM
image of a 16 nm Fe
3
O
4
NP. (d)-(f) Size effect on MRI contrast: (d) TEM images of Fe
3
O
4
NPs
with different sizes, (e) the relevant
T
2
-weighted MR images and color-coded maps, and (f)
relation of size, saturation magnetization, and relaxivity
r
2
. (Reprinted with permission from
Refs. [32] and [33]. © american chemical Society). (
See insert for color representation of the
figure.)
)
ether with benzyl ether, a solvent with higher boiling point (300°c), 6 nm Fe
3
O
4
NPs could be produced. larger Fe
3
O
4
NPs were also made
via
the seed-mediated
growth. For instance, 8 nm Fe
3
O
4
NPs were produced by thermally decomposing
Fe(acac)
3
in the presence of 6 nm Fe
3
O
4
NP seeds. Varying the seeds with different
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