Biomedical Engineering Reference
In-Depth Information
considering a possible
in vivo
application, the CNTs were completely
destroyed with this treatment, thereby avoiding any problem associated with
their intrinsic toxicity.
The modulation of NIR pulses can induce a controlled local heating without
killing the cells but enhancing the permeability of tumour vasculature, with
the possibility of ameliorating the drug delivery in a combined chemotherapy
approach
64
or inducing endosomal disruption with the consequent release of
cargos (as oligonucleotides) linked to nanotubes.
61
Another very interesting possibility in the thermal ablation treatment of
cancer is given by the use of a non-invasive radiofrequency (RF) ield, instead
of NIR irradiation.
71
Gannon
et al.
reported the heating of the SWCNT solution
when exposed to a RF ield. It is important to point out that the RF wavelength
exceeds the CNTs' length too much to give rise to resonance and the energy
is too small to excite electronic transitions. So, this thermal effect could be
due to the resistive conductivity of SWCNTs and their high aspect ratio. In
this study, both
in vitro
and
in vivo
experiments have been carried out. For
the former, cytotoxicity was observed for CNT-treated cells exposed to a RF
ield. This effect resulted to be dependent on the SWCNTs concentration and
on the duration of RF exposure. For the
in vivo
studies, solutions of nanotubes
were administered via intratumor injection into tumour-bearing rabbits. The
animals were then treated with an RF ield, leading to necrosis of the tumour
tissue. In both sets of experiments, control treatments, i.e., a RF ield without
SWCNTs and SWCNTs without a RF ield, were unable to exert any toxicity on
the tumours. This inding opens a new perspective in the application of CNTs
for cancer treatment.
Magnetic luid hyperthermia, induced by an alternating current magnetic
ield in the presence of magnetic nanoparticles, can be exploited for cancer
therapy, and CNTs can be really useful in this ield. The preparation of CNTs
encapsulating ferromagnetic particles was achieved by pyrolysis of ferrocene,
resulting in the formation of forests where the tubes are vertically aligned.
Adherent human bladder cancer cells (EJ28) were incubated in the presence
of a suspension of CNTs with and without cationic lipids. In the irst case
no adhesion was found, while the presence of lipids helped the entrance of
CNTs into cells with a cytoplasmatic localisation.
72
Borowiak-Palen, instead,
reported the preparation of CNTs illed with
α
-Fe (iron allotrope with a body-
centred cubic lattice) using a different procedure. The SWCNTs produced
by laser ablation were irst puriied and subsequently illed with FeCl
3
and,
inally, washed to remove the externally deposited iron.
73
These compounds,
variously modiied and bearing anticancer drugs, can be used to target
lymphatic tissues.
74
No real application of this approach has been reported up to now, but
Pensabene
et al.
reported that by catalytic chemical vapour deposition,
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