title: Use of a DNA film on a self-assembled monolayer for investigating the physical process of DNA damage induced by core electron ionization.
abstract: A novel two-layer sample composed of a deoxyribonucleic acid (DNA) film and self-assembled monolayer (SAM) was prepared on an inorganic surface to mimic the processes in which DNA is damaged by soft X-ray irradiation.
  
  
  
  A mercaptopropyltrimethoxysilane (MPTS) SAM was formed on a sapphire surface, then oligonucleotide (OGN) molecules were adsorbed on the MPTS-SAM. The thicknesses and chemical states of the layers were determined by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray fine structure (NEXAFS) around the phosphorus (P) and sulfur (S) K-edges. To induce the damage to the OGN molecules, the sample was irradiated with synchrotron soft X-rays. The chemical state of the OGN molecules before and after irradiation was examined by NEXAFS around the nitrogen (N) K-edge region.
  
  
  
  The thickness of the MPTS-OGN layer was approximately 7.7 nm. The S atom of the OGN molecules was located at the bottom of the OGN layer. The peak shape of the N K-edge NEXAFS spectra of the MPTS-OGN layers clearly changed following irradiation.
  
  
  
  The MPTS-OGN layer formed on the sapphire surface. The chemical states and the structure of the interface were elucidated using synchrotron soft X-rays. The OGN molecules adsorbed on the MPTS films decomposed upon exposure to soft X-ray irradiation.
authors.affiliation: a Japan Atomic Energy Agency , Shirakata, Tokai , Naka , Ibaraki , Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Narita
authors.affiliation: a Japan Atomic Energy Agency , Shirakata, Tokai , Naka , Ibaraki , Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Fujii
authors.affiliation: a Japan Atomic Energy Agency , Shirakata, Tokai , Naka , Ibaraki , Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Baba
authors.affiliation: a Japan Atomic Energy Agency , Shirakata, Tokai , Naka , Ibaraki , Japan.
authors.forename: Iwao
authors.initials: I
authors.lastname: Shimoyama
mesh_terms: D000327:Adsorption; D040761:Biomimetic Materials / Q000138:chemical synthesis / Q000528:radiation effects; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis / Q000528:radiation effects; D004247:DNA / Q000737:chemistry* / Q000528:radiation effects*; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D004583:Electrons; D008422:Materials Testing; D008567:Membranes, Artificial; D017646:Organosilicon Compounds; D011829:Radiation Dosage; D012821:Silanes / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D020099:Coated Materials, Biocompatible; D008567:Membranes, Artificial; D017646:Organosilicon Compounds; D012821:Silanes; C102833:(3-mercaptopropyl)trimethoxysilane; D004247:DNA
keywords: DNA damage; X-ray photoelectron spectroscopy; chromatin structure; near-edge X-ray absorption fine structure; self-assembled monolayer; synchrotron X-ray