The Auger electron therapy of cancer driven by mono-energetic X-rays with the vector nanoparticles loaded with Iodine

Irradiation of high Z elements with monoenergetic X-rays causes photoelectric effects that include the release of Auger electrons. These electrons have strong DNA damaging effects including double strand DNA cleavage. This approach has been explored as a potential cancer therapy (the Auger therapy). We first developed gadolinium loaded mesoporous silica nanoparticles (Gd-MSN) and demonstrated their ability to destroy tumor spheroids upon irradiation with synchrotron generated (SG) monochromatic X-rays of 50.25 keV. We now tried Iodine with a K-edge energy of 33.2 keV. We show that the destruction was dependent on the presence of iodine and that the destruction effect is highly dependent on monochromatic X-ray energy. Results of experiments using three different energy levels (33.0, 33.2 and 33.4 keV) demonstrated that spheroid destruction, apoptosis induction and double strand DNA breaks occurred with the 33.2 keV X-ray irradiation, but not with 33.0 keV irradiation and less with 33.4 keV irradiation.