Biomedical Engineering Reference
In-Depth Information
O
Ab1
N
H
O
Ab2
N
H
18
19
= PEG
= phospholipid-PEG-FITC
= phospholipid-PEG-Folic acid
Figure 3.12
Structures of compounds
18
and
19
. See also Colour Insert.
functionalising CNTs with 1-pyrenebutanoyl succinimmide, which can stack
to the aromatic surface of the nanotubes by π-π interaction and which bears
a group for the attachment of the antibodies.
62
Cells incubated with
19
were
then excited by 808 nm photons at 800 mW/cm
2
for 3 minutes. This treatment
induced nanotube heating, with the consequent death of the cells, which had
internalised CNTs. All cells incubated with
19
were destroyed, while 80%
of the cells treated with non-speciic antibody-SWCNT constructs survived,
indicating selective CNT internalisation due to speciic receptor recognition
on cancer cells.
In another recent work, SWCNTs conjugated with a speciic monoclonal
Ab were prepared and delivered to human cells bearing a speciic antigen for
the Ab.
63
Subsequently, they were treated with an NIR laser (808 nm, 5 W/
cm
2
for 7 minutes), resulting in a signiicant decrease in cell viability.
MWCNTs are expected to be more eficient than SWCNTs in adsorbing
NIR radiation and inducing the heating-up process because of more electrons
available for absorption per particle and more metallic tubes than SWCNTs. So,
they were chosen to treat renal cancer (RENCA) cells, and a 62-fold reduction
in cell viability was obtained when the cultures were exposed to NIR laser
illumination for 45 seconds. The experiments were also performed
in vivo
,
demonstrating that the tumour tissue heated up to 74°C in the presence of
MWCNTs (100 μg) and laser illumination (30 seconds, 3W/cm
2
, 1064 nm
continuous-wave), with a consistent decrease in tumour volume, while 46°C
was reached after the tissue was exposed to simple laser illumination.
64
The same authors studied this effect using nitrogen-doped MWCNTs, which
present pyridine-like rings within their structure. This chemical composition
results in better conduction properties due to the subsequent illing of the
small band gap in MWCNTs.
65
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