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内容記述 |
Gold Nanoparticles (GNPs) are known as a radiosensitizer. The increase of the biological effectiveness due to GNPs has been reported, but the mechanisms are not satisfactory understood. To unveil the enhancement mechanisms, we evaluate changes in yields of water radiolysis species (hydrogen peroxide and OH radicals) under X-rays, protons and heavy ions.One of the enhancement mechanisms has been considered as the increase of reactive oxygen species formed by water radiolysis. Previously, using plasmid DNA, it was reported that the decomposition of hydrogen peroxide in the presence of GNPs led to the increase of OH radicals. To verify the relation between hydrogen peroxide decomposition and OH radical increase, we evaluate yields of hydrogen peroxide formed by water radiolysis in the presence and in the absence of GNPs. Hydrogen peroxide is quantified using Ghomley technique and OH radicals are measured by Amplex Red solutions.Hydrogen peroxide formed by water radiolysis species is completely decomposed in the presence of GNPs. In the case of X-rays, hydrogen peroxide formed increase with dose above 25 Gy. As the decomposition of hydrogen peroxide, yields of OH radicals increase significantly in the presence of GNPs, compared to that in the absence of them. Similar trends are seen under protons and heavy ions. Indeed, GNPs have been inactivated above certain doses under the irradiation. Thus, hydrogen peroxide could be decomposed by redox reactions in the presence of GNPs, leading to the increase of OH radicals. In the presentation, we will present our recent advances of biological experiments using living cells. |
