Cancer cell death is triggered within three days when X-rays are shone onto tumor tissue containing iodine-carrying nanoparticles. The iodine releases electrons that break the tumor’s DNA, leading to cell death. The findings, by scientists at Kyoto University’s Institute for Integrated Cell-Material Sciences (iCeMS) and colleagues in Japan and the US, were published in the journal Scientific Reports.

“Exposing a metal to light leads to the release of electrons, a phenomenon called the photoelectric effect. An explanation of this phenomenon by Albert Einstein in 1905 heralded the birth of quantum physics,” says iCeMS molecular biologist Fuyuhiko Tamanoi, who led the study. “Our research provides evidence that suggests it is possible to reproduce this effect inside cancer cells.”

A long-standing problem with cancer radiation therapy is that it is not effective at the center of tumors where oxygen levels are low due to the lack of blood vessels penetrating deeply into the tissue. X-ray irradiation needs oxygen to generate DNA-damaging reactive oxygen when the rays hit molecules inside the cell.