Biomedical Engineering Reference
In-Depth Information
(a)
CTAB
TEOS
Extraction
and TEOS
of CTAB
Fe
3
O
4
@nSiO
2
@CTAB/SiO
2
Fe
3
O
4
@nSiO
2
@mSiO
2
Fe
3
O
4
Fe
3
O
4
@nSiO
2
(c)
(d)
(b)
100 nm
100 nm
200 nm
200 nm
(e)
(f )
(g)
nSiO
2
Fe
3
O
4
2 µm
mSiO
2
50 nm
10 nm
FIGURE 3.6
(a) The formation of Fe
3
O
4
@nSiO
2
@mSiO
2
nanoparticles. TEM images of (b) Fe
3
O
4
particles, (c)
Fe
3
O
4
@nSiO
2
, (d-f) Fe
3
O
4
@nSiO
2
@mSiO
2
nanoparticles, and (g) SEM image of Fe
3
O
4
@nSiO
2
@
mSiO
2
nanoparticles. (Reprinted with permission from Deng Y., Qi D., Deng C., et al.,
J. Am.
Chem. Soc.
130: 28-29, Copyright 2008, American Chemical Society.)
of TEOS and
n
-octadecyltrimethoxysilane (C18TMS) followed by the
removal of the organic group. Finally, α-Fe
2
O
3
cores of the nanoparticles
were reduced in a flowing H
2
/N
2
gas mixture to produce the final mag-
netic mesoporous silica nanoparticles with a core-shell structure (Fe
3
O
4
/
Fe@nSiO
2
@mSiO
2
nanoparticles). Using IBU as a model drug to explore the
capability as drug carriers, the loading amount of IBU was ca. 12 wt%, as
assessed by TG analysis, and the release in a simulated body fluid (SBF)
can keep over 70 h, allowing for the potential application in targeting drug
delivery. The prepared magnetic mesoporous silica nanoparticles have a
high magnetization value (27.3 emu/g), but its ferromagnetic property may
limit its practical application in some areas. Deng et al. (2008) synthesized
superparamagnetic particles with Fe
3
O
4
cores and perpendicularly aligned
mesoporous silica shells through a three-step process (see Figure 3.6). First,
nonporous silica/Fe
3
O
4
nanoparticles were prepared by coating a thin silica
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