Biomedical Engineering Reference
In-Depth Information
tumor effects of sodium and its controllability as an economic, safe and efficient
thermochemical agent in targeted tumor treatment were disclosed. Followed their
work, Cressman et al. evaluated exothermic permanganate redox chemistry for
utility in tumour ablation and proved it a powerful system with potential to
increase tumor temperature. The maximum temperature could reach 97.4°C in the
experiments. They also used different reagent volumes, concentrations, injection
order, and substrate choice to study the parametric effect over the reaction
(Cressman et al.
2010
).
Similarly, nanoparticles can also be combined with thermochemical reaction
method to enhance the effect of cancer treatment. For one hand, nanoparticles could
be used as the catalysts to accelerate the reactions. They have small size and large
ratio of surface area to volume. And the bonding states and the valence states for
surface atoms are different with that of inner atoms resulting in increased surface
activity. Therefore, nanocatalytic activity and selectivity are much higher than that
of traditional catalysts. For example, CuO at micro-level does not have catalytic
activity for decomposition of H
2
O
2
, while when the particle size is reduced to
nanometer grade, it shows high catalytic activity. Besides, metal nanoparticles can
fracture catalytically H-H, C-C, C-H and C-O bond, so that speeding up response
time. Wu et al. showed that for the ethane oxidation dehydrogenation reaction,
nano-NiO catalyst play better role than conventional NiO catalyst at lower tempe-
rature (Cao et al.
2005
). Bennett loaded nano-Pd on TiO2 and catalyzed 1-hexene
hydrogenation reaction to produce more hexane than conventional palladium cata-
lysts (Bennett
1989
).
On the other hand, some nanoparticles could be used as mediums involved in
chemical reactions to produce heat. Nano-materials have small size, large percent-
age of surface atoms, superior adsorption ability and high surface reactivity. Metal
nanocrystals are easy to oxidize; even corrosion-resistant nitride ceramic materials
are also unstable when their diameters reduce to nanoscale.
7
Other Heating Methods Through Delivering Heat Directly
The common purpose for all the heating methods is to convert other forms of
energy into heat at tumor tissue. Therefore, if one could inject heat energy directly,
the effect may be better.
The electrothermal needle mainly used in traditional Chinese medicine is
such a heating method. It is originated from fire needle, and can insert directly
into the central of tumor. When energy reaches 165 cal and lasts for 40 min, the
central temperature can reach 56°C while the surrounding tissue stays at only
44°C ~ 47°C. Apart from this, the temperature of electrothermal needle can
adjust by changing electric current, so it can extend the treatment time to
enhance the effect. Electrothermal needle method is more easily operated than
other hyperthermia approaches to reduce tumor proliferation and metastasis.
Maybe there are still other ways similar to electrothermal needle to provide heat
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