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Light-Activated Cancer Therapy Isn’t Just Skin Deep

Nanoparticles used in combination with X-rays can be used to kill cancer cells deep within the body, according to research published in Scientific Reports (

The research is based on the successful quantification of singlet oxygen, a highly reactive form of oxygen that has been used in photodynamic therapy to kill or inhibit the growth of cancer cells. “Photodynamic therapy is where light-sensitive compounds are placed near diseased cells, then activated by light, producing short-lived molecular by-products that can destroy or damage the cells being targeted,” explains Prof Ewa Goldys of Macquarie University.

“In this case, X-rays were used to stimulate cerium fluoride (CeF3) nanoparticles which had been placed near a group of cells. Singlet oxygen was produced as a by-product of the X-ray and CeF3 interaction, which was then successfully measured.

“Singlet oxygen molecules are a far more reactive form of oxygen but they can only kill cancer cells if generated in sufficient quantity”, said Goldys. “In our testing we established that therapeutic radiation dose X-rays produce enough singlet oxygen molecules to be effective in photodynamic therapy.”

Goldys says photodynamic therapy has traditionally used near-infrared or visible light, but this has been unable to penetrate far into the body, limiting its use to cancer treatment on or near the surface of the skin. “We’re looking to target cancer cells deeper in the body, hence the use of X-rays, which can really penetrate into deeper levels of tissue, and which are already used in medical diagnosis and therapy. The beauty of this type of treatment is that it uses different biological pathways to kill cells as compared to chemotherapy, radiotherapy and other current cancer practices.”

Different nanoparticles will next be tested for their effectiveness in producing singlet oxygen.