Physicists at the University of Texas at Arlington have shown that using microwaves to activate photosensitive nanoparticles produces tissue-heating effects that ultimately lead to cell death within solid tumors. The new concept, which combines microwaves with photodynamic therapy, opens new avenues for targeting deeper tumors and has proven effective in rapidly and safely reducing tumor size.
"Our new method using microwaves can propagate through all types of tissues and target deeply situated tumors," said Wei Chen, UTA professor of physics and lead author of the study titled "A new modality of cancer treatment-nanoparticle mediated microwave induced photodynamic therapy."
Photodynamic therapy kills cancer cells when a nanoparticle introduced into tumor tissue generates toxic singlet oxygen after being exposed to light. Singlet oxygen is a highly reactive type of oxygen that irreversibly damages cell mitochondria and eventually causes cell death.
In prior studies, the researchers had identified a new type of nanoparticle, copper-cysteamine or Cu-Cy, that could be activated by X-rays to produce singlet oxygen and slow the growth of tumors. X-ray radiation, however, poses significant risks to patients and can harm healthy tissue.
In this new lab study, the team demonstrated that the nanoparticle Cu-Cy also can be activated by microwaves, which can be targeted directly at the tumor itself without harming surrounding tissue.
"Our new microwave-induced photodynamic therapy offers numerous advantages, the most significant of which is increased safety," Chen said. "Our nanoparticle Cu-Cy also demonstrates very low toxicity, is easy to make and inexpensive, and also emits intense luminescence, which means it can also be used as an imaging agent."