Biomedical Engineering Reference
In-Depth Information
Fig. 17
Zinc (II)
phthalocyanine (ZnPc)
(Reproduced by permission
of The Royal Society of
Chemistry)
N
N
N
N
Zn
N
N
N
N
markers or drug and gene delivery platform. MSN possess advantages such as large
surface area and pore volume, as well as uniform pore size. They are both a suitable
carrier for hydrophobic molecules and a way to protect the PS from degradation.
ZnPc - and Fe
3
O
4
-loaded MSN (ZnPc or Fe
3
O
4
/MSN) were prepared through a
one-pot
procedure under basic conditions in the presence of cetyltrimethylammo-
nium bromide CTAB as structurating agent and Fe
3
O
4
nanoparticles. Near spherical
or rounded cubic nanoparticles were obtained with a size in the range of 60-120 nm.
According to narrow-angle X-ray diffraction pattern of MSN and ZnPc or Fe
3
O
4
/
MSN, a slightly disordered mesoporous structure was observed. A widening of the
pore size from 3.6 to ~4 nm was also calculated. Wide-angle X-ray diffraction pat-
tern of ZnPc or Fe
3
O
4
/MSN displayed the characteristic peaks of the amorphous
silica matrix and the cubic inverse spinel Fe
3
O
4
. Magnetic measurements showed a
superparamagnetic behavior at 1.0 T, which is enough for MRI and magnetic
hyperthermia applications. UV-visible spectroscopy showed the presence of non-
aggregated ZnPc molecules entrapped in the silica matrix. However, experiments
concerning singlet oxygen generation or PDT still have to be carried out. Drug
delivery experiments were performed with ibuprofen as guest molecules. The load-
ing of ibuprofen was realized by dispersing and stirring MSN or ZnPc/Fe
3
O
4
/MSN
in a solution of ibuprofen in hexane and the release of ibuprofen in distilled water
could be monitored by UV-visible spectroscopy. It appeared that ZnPc/Fe
3
O
4
/MSN
showed a more delayed and steady release of ibuprofen compared to MSN. This
effect could be attributed to the interaction between ibuprofen and the ZnPc
entrapped in the silica matrix.
Liu et al. (
2009
) described the preparation of photodynamic drug nanocarriers
consisting of magnetite and photosensitizer (PHPP, Fig.
14
), surrounded by a silica
shell through a sol-gel process in a micellar media. TEM analyses showed nanocar-
riers with a nearly spherical shape in the range of 30-50 nm which tend to aggre-
gate. XRD analyses showed the typical patterns of magnetite in addition to the
broad diffraction band at ca. 2q = 20° corresponding to the amorphous silica matrix.
The photosensitizer entrapped in the silica matrix was detected by FT-IR and
UV-visible spectroscopy. Upon irradiation using 637 nm laser,
1
O
2
was produced
and released from the nanocarriers. The RNO-bleaching method, allowed the deter-
mination the
1
O
2
generating efficiency. Compared to the free PHPP, the results
obtained showed that: (1) the photosensitivity of the nanocarriers was less but still
effective for potential PDT applications and (2) the presence of Fe
3
O
4
and silica
shell had no critical effect on the production and release of
1
O
2
.
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