Biomedical Engineering Reference
In-Depth Information
Microemulsion technique was performed with AOT and butanol as surfactants
and vinyltriethoxysilane and aminopropyltriethoxysilane as the reagents for the
gelation procedure. The nanoparticles exhibited a diameter of 30 nm which is
smaller than in previously described procedures.
1
O
2
production measured by its
emission at 1,270 nm and by reaction with ADPA was very efficient. The nanopar-
ticles were taken up by HeLa and UCI-107 cancer cells as confirmed by fluores-
cence of HPPH at 665 nm. The nanoparticles were very efficient in killing cancer
cells after irradiation at 650 nm as analyzed by MTT assay.
Qian et al. encapsulated Protoporphyrin IX (PpIX, Fig.
7
) in silica nanoparticles
(Qian et al.
2009b
), following Prasad's method. Monodispersed and spherical nano-
particles with a 25 nm diameter were obtained. Absorption and fluorescence spec-
tra of free PpIX in DMSO and encapsulated PpIX were similar, even if PpIX
encapsulating nanoparticles had a non negligible scattering efficiency (due to the
25 nm diameter) and the fluorescence was 2 nm red-shifted due to the different
surroundings.
1
O
2
was detected indirectly with 1,3 diphenylisobenzofuran (DPBF).
In vitro
PDT was performed on HeLa cells by a 532 nm light source irradiation
(2 mW/cm
2
, 2 min). After 8 min of irradiation, changes could be observed in the
HeLa cells and the cell structures were destroyed.
The team of Reddi investigated the encapsulation of
m
-THPC into organic-
modified silica nanoparticles of 33 ± 9 nm diameter following Prasad's method
(Compagnin et al.
2009
). They showed that
m
-THPC was entrapped in a mono-
meric form and produced
1
O
2
with a high efficiency. In aqueous media with high
salt concentrations, the nanoparticles underwent aggregation and precipitation but
their stability could be preserved in the presence of foetal bovine serum (3%). The
cellular uptake of
m
-THPC (Fig.
10
) entrapped in organically modified silica nano-
particles was shown to be mediated by serum proteins. The
in vitro
studies were
realized on human oesophageal cancer cells KYSE 510 and the entrapped
m
-THPC
was compared to
m
-THPC diluted into the standard solvent ethanol/
poly(ethyleneglycol) 400/water (20:30:50, by vol). In the absence of light, the two
formulations did not affect the viability of the cells up to a
m
-THPC concentration
of 1.75 mM. Phototoxicity was determined after 24 h dark incubation and irradia-
tion with a light (600-700 nm, PTL Penta quartz halogen lamp, 2 mW cm
−2
) of
0.12 J.cm
−2
. All cells were killed after incubation with 1.25 mM
m
-THPC. The dose-
response curves obtained by incubating the cells with increasing concentrations of
m
-THPC delivered by the two formulations were identical but the nanoparticles
formulation reduced the cellular uptake of
m
-THPC by about 50% in comparison
to standard solvent. With an elegant Förster Resonance Energy Transfer (FRET)
approach, using a cyanine as an acceptor covalently linked to the nanoparticles, the
authors demonstrated that
m
-THPC is transferred from the nanoparticles to serum
proteins of the medium. To prevent this transfer to proteins it was necessary to coat
the nanoparticles surface with poly(ethylene glycol).
Another type of PS based on hydrophobic silicon phthalocyanine
Pc
4 (Fig.
3
)
was encapsulated in ORMOSIL by the method originally developed by Prasad's
group with some modifications (replacement of AOT by Tween 80 as surfactant)
which led to nanoparticles with a 25-30 nm diameter (Zhao et al.
2009
). Compared
Search WWH ::
Custom Search