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Comparison of Effects of Plateau Carbon-Ion Beams and X-rays on the Redox States of Aqueous and Organic Solutions of 2,2-Diphenyl-1-picrylhydrazyl Radical
利用統計を見る
Carbon-ion (C-ion) beams are known to exhibit a sharp maximum of the energy deposition, called as a Bragg peak, at a certain penetration depth. Thus, the cancer cells are precisely killed by adjusting the Bragg peak to a tumor. However, the dose in the plateau region of the C-ion beams before the Bragg peak is not necessarily zero. In this study, the redox states of aqueous and organic solutions
after irradiation by the plateau C-ion beams were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical as a redox probe.
Irradiation of the C-ion beams (290 MeV per nucleon, 13 keV/mum) was carried out using the Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences, Japan. A Shimadzu Pantak HF-320 was used for X-irradiation (X-ray tube voltage: 200 kV, X-ray tube current: 20 mA, pre-filter: 0.5 mm Cu + 0.5 mm Al, dose rate: 1.78 Gy/min).
C-ion irradiation of aqueous solutions of the DPPH radical solubilized by beta-cyclodextrin in water resulted in the decrease in the absorption band at 527 nm due to the DPPH radical. The absorbance at 527 nm linearly decreased with increasing the radiation dose. When C-ion beams were replaced by X-rays, the slope of the linear plot is about the same as that in the case of C-ion beams. Similar results were obtained
when H2O was replaced by methanol or acetonitrile without beta-cyclodextrin, although the slope values were twice larger as compared to the cases in H2O. On the other hand, the DPPH radical was more susceptible to the C-ion beams or X-rays in isopropyl myristate (IPM), a saturated fatty acid ester, than in H2O, methanol, and acetonitrile. Furthermore, the C-ion beams consumed the DPPH radical more effectively than X-rays in IPM, suggesting that lipid molecules may be more susceptible to the effectively than X-rays in IPM, suggesting that lipid molecules may be more susceptible to the C-ion beams than to X-rays. The mechanism will also be discussed based on the product analysis by the electron spin resonance (ESR) spin-trapping.
会議概要（会議名, 開催地, 会期, 主催者等）
25th Annual Conference of the Society for Redox Biology and Medicine (SfRBM 2018)
Comparison of Effects of Plateau Carbon-Ion Beams and X-rays on the Redox States of Aqueous and Organic Solutions of 2,2-Diphenyl-1-picrylhydrazyl Radical
