Enhancement of DNA damages by platinum nanoparticle

Abstract

A compound having a relatively heavy atom would be a target molecule of radiotherapy, because of its large X-ray absorption coefficient. We have investigated the mechanisms of enhancement of the radiation biological effect by such a radiosensitizer, mainly using a platinum-containing molecules, chloroterpyridine platinum II (PtTC). The spatial distribution of the compoinds within the cell, is a very important factor for radiosensitization. We found that PtTC was not incorporated in the cell nucleus, although it showed a certain level of enhancement of the cell death. Recently, we started to use platinum-nanoparticle as the one of the candidate of an effective radiosensitizer. The metallic nanoparticle, can be modified its function by changing of the surface molecules. Solution of plasmid DNA, mixed with platinum nanoparticle, was irradiated with carbon ions (HIMAC, NIRS) or monochromatic soft X-rays (Photon Factory, KEK). The enhancement of the DNA strand breaks was almost same level as the PtTC.