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further functionalized with glutaraldehyde and used in streptavidin
immobilization. In another report, Gai
. [87] used a sol-gel
method to fabricate a magnetic-luminescent core-shell Fe
et al
O
@
3
4
3+
3+
3+
SiO
nanocomposite. The mesoporous,
upconversion luminescent and magnetic nanocomposites (Fig.
2.19b) act as a multifunctional drug carrier system. Zhang
@NaYF
:Yb
,
Er
/Tm
2
4
et al
.
[93] reported hydrothermally synthesized Fe
O
and Y
O
:Tb
2
3
2
3
shell to fabricate multifunctional
nanocomposite for potential simultaneous diagnosis and therapy
(Fig. 2.19c).
nanoparticles embedded in a SiO
2
(a)
(b)
(c)
Figure 2.19
TEM image of (a) upconversion fluorescent (NaYF
)-magnetic
nanoparticles (iron oxide) with surface-coated silica shells
[85]; (b) multifunctional Fe
4
3+
O
@nSiO
@mSiO
@NaYF
: Yb
,
3
4
2
2
4
Er
3+
nanocomposties [87]; (c) Fe
O
@silica/Y
O
:Tb hybrid
3
4
2
3
multifunctional nanostructures [93].
In many cases, highly monodisperse and uniform nanocrystals
are synthesized in organic solvents. To use them in biological
study, it is essential to render them water-dispersible. Coating
these nanoparticles with polymer and/or silica shell renders the
nanoparticles water dispersible and provides a further platform for
bioconjugation. Das
. [84] demonstrated a strategy of putting
a thin layer of silica onto Y
et al
nanomaterials to render them
water dispersible (Fig. 2.20a), while in another study, Zhong
O
2
3
.
[94] demonstrated a hydrothermal method to synthesize PVP/
silica-coated water dispersible particles to be used as biolabels
(Fig. 2.20b).
et al
