Nanoparticles Enhanced Hyperthermia - Intracellular Delivery: Fundamentals and Applications - page 583

mass in vivo. Upon irradiation of DNA-encased MWNTs, heat is generated with a
linear dependence on irradiation time and laser power (Ghosh et al. 2009 ).

3.3.2 Theoretical Modeling on Temperature Fields During

Gold Nanoshells Enhanced Optical Hyperthermia

There are many experiments in vivo or vitro on the nanoparticles used in the PTT
currently. However, there is a strong lack of understanding the energy distribution
and the transient temperature field in the tissues due to addition of nanoparticles.
Recent efforts were made on theoretical modeling the optical and temperature fields
during gold nanoshells enhanced hyperthermia through combining the Monte-Carlo
simulation strategy and the Pennes bioheat transfer equation. Effects of size, con-
centration of the nanoshells to the heating behaviors were predicted and the method
would serve well for future treatment planning for the nanoshells enhanced LITT
on target tumor tissues (Wang et al. 2010 ).

4 Nanoparticles Enhanced Electrical Hyperthermia

4.1 Basic Features

RF ablation is another type of tumor hyperthermia therapy relying on the adminis-
tration of RF irradiation. RF ablation inserts an electrode into the tumor and applies
a RF current, which induces agitation of the ions within the tissue, leading to fric-
tional heating. As is well known, for a given RF power output, the power deposition
at each point in space is strongly dependent on the local electrical conductivity. RF
frequency and amplitude, and the electrical conductivity of the tissue determined
the SAR which is expressed as

= ò

SAR s | E |

2

/

r dr (8)

sample

Thus, improving the conductivity around the tumor tissue is the way to enhance
the RF ablation effect. it has been demonstrated that altering electrical conductivity
of tissue through saline injection prior to or during RF ablation can increase RF
tissue coagulation volume (Lobo et al. 2004 ).
Recently, it was further demonstrated that nanoparticles with high electrical
conductivity can be used as effective adjuvants to induce hyperthermia in vitro and
in vivo upon irradiation with an external 13.56 MHz RF field (Gach et al. 2010 ).
The presence of nanoparticles can be targeted to malignant cells and provide a
possibility of non-invasive RF treatment, compared with traditional RF treatment
which will insert an electrode into the tumor.
RF ablation is now used in clinical practice to treat some malignant tumors, yet
nanoparticles enhanced radiofrequency is still a new method and need more studies.