Nanoparticles Enhanced Hyperthermia - Intracellular Delivery: Fundamentals and Applications - page 568

MW Microwave

MWNT Multi-walled carbon nanotubes

NIR Near-infrared

PTT Photothermal therapy

PVA Polyvinyl alcohol

RF Radiofrequency

SAR Specific absorption rate

SPM Superparamagnetic

SWNT Single-walled carbon nanotube

UCA Ultrasound contrast agents

UHF Ultra high frequency

VHF Very high frequency

1 Background

Hyperthermia (Liu and Deng 2008 ; Alpard et al. 1996 ), one of newly emerging
approaches currently being tested for cancer therapy, is known as “green therapy”
for cancer treatment compared with conventional resection surgery, chemotherapy,
and radiotherapy. It is a procedure of heating tissues to a higher temperature level than
that of normal tissues in order to kill tumor (Alpard et al. 1996 ). There are generally
two kinds of heating strategies. One is mild hyperthermia performed between
41°C and 46°C to stimulate the immune response for non-specific immunotherapy
of cancers. Another is thermal ablation (more than 46°C, even much higher) leading
to tumor destruction by direct cell necrosis, coagulation or carbonization. In a con-
ventional hyperthermia, however, due to difficulty to precisely control heating, low
accuracy in temperature measurement and possibility of damaging healthy tissues due
to overheating, it often leads to survival, transfer, diffusion, or even re-generation
of tumor cells. To tackle such tough technical barriers, nano-hyperthermia was
recently identified as a promising way to improve conventional heating. Its basic
idea is to load nanoparticles with specific functions into tissues to help achieve the
desired heating on the target tissues. This is because the nanoparticles can help
induce much larger heat and thus higher temperature. Particularly, selectively loading
particles to carefully designed tissue site will enable a conformal heating. This would
expand the scope of conventional hyperthermia heating equipment. In addition,
it can administrate a more accurate treatment on cells and in sub-cellular scale.
In general, controlling temperature range, heating time, and heating rate can be well
improved after loading nanoparticles.
Since Gilchrist et al. ( 1957 ) proposed the concept of magnetically mediated
hyperthermia and proved that magnetic particles can be selectively deposited in
the body and heat tumor tissue, researchers throughout the world have made
unremitting efforts. Particularly in recent years, Jordan et al. successfully lead nano-
particle enhanced hyperthermia to clinical trials. In addition, many labs are also