Nanoparticles Enhanced Hyperthermia - Intracellular Delivery: Fundamentals and Applications - page 584

4.2 Types of Nanoparticles Enhancing the Conductivity

Nanoparticles with good conductivity properties, such as GNPs and CNTs, are
studied to provide the possibility of more efficient heating under RF field exposure
recently.

4.2.1 Carbon Nanotubes

SWNTs can act efficiently to convert RF irradiation into heat, which is possible due
to their resistive conductivity property (Gannon et al. 2007 ; Cherukuri et al. 2010b ;
Day et al. 2009 ). For SWNTs, the rate of heating depends on the concentration.
Gannon et al. injected SWNTs or control solutions into Hepatic VX2 tumors of
rabbits and the rabbits were treated in the RF field. The RF field induced lethal
thermal injury to the malignant cells under efficient heating of aqueous suspensions
of SWNTs (Gannon et al. 2007 ).

4.2.2 Gold Nanoparticles

GNPs within a tumor can significantly increases the tissue temperature upon expo-
sure to RF energy other than used in the photothermal therapy as the optical sensors
(Cardinal et al. 2008 ; Gannon et al. 2008 ; Curley et al. 2008 ; Glazer et al. 2010 ).
Increasing GNPs concentration and increasing power of RF field both contributed
to increased temperature and rate of heating (Gannon et al. 2008 ).
Cardinal et al. ( 2008 ) directly injected the GNPs into the tumor of rats in vivo
and exposed at 35 W, demonstrating significant temperature increases and thermal
injury at subcutaneous injection sites as compared to water injection controls. Evan
et al. (Glazer et al. 2010 ) use 20-nm gold particle conjugated to cetuximab, which
is an EGFR-1 antibody over expressed by pancreatic carcinoma cells in an RF field
with a generator power of 200 W for 5 min. The results showed that targeted cells
internalized a sufficient amount of antibody-conjugated GNPs to induce injury in a
noninvasive RF field, while the non-targeted cells did not.
When comparing the heating rates under RF field exposure, GNPs seem to
provide a more efficient system over SWNTs. This suggests that GNPs may be better
conductors of RF energy than SWNTs and may provide a better application for RF
tumor ablation.

5 Nanoparticles Enhanced Ultrasound Hyperthermia

Ultrasonic heating method, whose energy is easy to produce and focused, spreading
non-destructively within the organization, has become an important heating means
in tumor hyperthermia. Traditional ultrasound hyperthermia treatment generally