Biomedical Engineering Reference
In-Depth Information
Fig. 23
Dimethyl-8,13-divinyl-3,
7,12,17-tetramethyl-21
H
,
23
H
-porphyrine-2,18-dipropyla
midopropyltriethoxysilane
(silyl-PpIX) (Reproduced by
permission of The Royal Society
of Chemistry)
NH
N
N
HN
CONH(CH
2
)
3
Si(OEt)
3
CONH(CH
2
)
3
Si(OEt)
3
(EtO)
3
Si
O
N
H
I
O
N
HN
NH
O
N
Fig. 24
Iodobenzyl-pyro-silane (IPS) (Reproduced by permission of The Royal Society of
Chemistry)
The coprecipitation of IPS with the commonly used ORMOSIL precursor vinyl-
triethoxysilane in the nonpolar core of Tween-80/water microemulsion led to the
formation of a monodispersed aqueous dispersion of ORMOSIL with covalently
linked IP. The particles were of about 20 nm diameter. Since the covalently incor-
porated PS molecules were found to retain their spectroscopic and functional prop-
ertiessuchasabsorptionorfluorescenceindependantlyoftheIPS/vinyltriethoxysilane
ratio used, the authors concluded that no aggregation occurred and that it could be
possible to increase the relative content of IPS within the nanoparticles to obtain
more
1
O
2
. To be sure that the generated
1
O
2
was not deactivated within the nanopar-
ticles, they used the
1
O
2
mediated bleaching of ADPA. They proved that
1
O
2
was
mainly deactivated outside the nanoparticles. Upon photoirradiation, cytotoxic
1
O
2
molecules were generated. Therefore, the nanoparticles were tested for cellular
uptake
in vitro
, on Colon-26 cells and proved to exhibit a manifest phototoxic effect
on the cultured cells proportional to the cellular uptake. In addition, the highest
photodynamic effect was associated to the highest content of the PS within the
nanoparticles, thus demonstrating the potential of the nanoparticles for PDT.
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