Biomedical Engineering Reference
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Si(OCH
3
)
4
(TMOS)
12 Pd
2+
24
1
2a-c
2a,c
⊃
silica nanoparticle
O
R
N
N
N
N
O
OH
O
OH
O
HO
HO
HO
O
1a
: R =
O
OH
OH
OH
1b
: R = H
3
C
1c
Figure 5.3
Synthesis of silica nanoparticles within self-assembled organo-metallic
nanospheres. Reprinted with permission from Ref. [20]. Copyright 2010 Macmillan
Publishers Limited.
prepared with self-assembled organometallic spheres as endo-templates [20]. In
the presence of metal (Pd) ions, a small-molecular compound with appended sugar
groups (
, Figure 5.3) assembles into nanospheres (nanogels) in dimethyl
sulfoxide (DMSO). The sphere interior lined with sugar residues acts as endo-
template for the sol-gel condensation of tetramethoxysilane (TMOS). Without
sugar groups (
1a
and
1c
, Figure 5.3), the condensation takes place in the bulk solvent. The
size of the silica nanoparticles (2-4 nm) was controlled by varying the size of the
nanospheres, which was achieved by changing the phenylene spacer (
1b
in
Figure 5.3). It was envisioned that this method could be used for the synthesis of
other types of nanoparticles. It is noteworthy that nanogels of polymers have been
used as templates recently for synthesis of nanoparticles [21]. The composites were
envisioned to have important applications such as in drug delivery.
1a
and
1c
5.2.3
Nanofibers/Tubes of Metal/Transition Metal Oxide and Sulfate
Nanostructured oxides of transitionmetals such as titanium (Ti), tantalum (Ta), and
vanadium (V) are generally accepted as the next generation materials in electronics
and advanced catalysts [22]. TiO
2
hollow fibers was first prepared by Kobayashi
et al
.
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