Biomedical Engineering Reference
In-Depth Information
Fig. 3
Encapsulated silicon
phthalocyanine 4 (
Pc
4)
N
N
N
HO
N
Si
N
O
Si
N
N
N
N
Fig. 4
Silicon
phthalocyanine 219
(
Pc
219)
Si
SH
O
N
N
N
N
Si
N
N
N
N
HO
cytoplasm. Knowing that few AuNPs were taken up into the cells, this implied that
most
Pc
4 molecules were released from the NPs before cellular uptake and were
delivered in the cells without the NPs at the cell membrane surface.
In vivo
experi-
ments on nude mice showed that the AuNP-
Pc
4 conjugates were accumulated
within 2 h at the tumor site.
Pc
4 molecules were also observed in the lung and the
kidneys (observation usually made with phthalocyanine photosensitizers). The
PEGylated AuNP nanocarriers accelerated the
Pc
4 administration by two orders of
magnitude without apparent side effects and modification of the distribution pattern
of
Pc
4 (similar to that of
Pc
4 free), and the effectiveness of the PDT treatment can
be deduced by observing a decrease of the size of the tumor which became necrotic.
Cheng et al. also showed that the delivery of the drug, and thus the PDT efficiency
are strongly affected by the nature of the bond between the photosensitizer and the
AuNPs (Cheng et al.
2010
). Here, AuNPs act as delivery vehicles for loosely bound
Pc
4 molecules which are then released in cancer cells. They carried out the same
kind of experiment with
Pc
219 which is the thiolated analogue of
Pc
4. (Fig.
4
) The
S-Au bonds (47 kcal/mol) are much more stable compared to the N-Au bonds, and
thus the released
Pc
219 molecules should be very low compared to the release of
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