Use of a DNA film on a self-assembled monolayer for investigating the physical process of DNA damage induced by core electron ionization

• Published in: International journal of radiation biology 2016-11, Vol.92 (11), p.733-738
• Main Authors: Narita, Ayumi, Fujii, Kentaro, Baba, Yuji, Shimoyama, Iwao
• Format: Article
• Language: English
• Subjects: Adsorption; Biomimetic Materials - chemical synthesis; Biomimetic Materials - radiation effects; chromatin structure; Coated Materials, Biocompatible - chemical synthesis; Coated Materials, Biocompatible - radiation effects; DNA - chemistry; DNA - radiation effects; DNA Damage; Dose-Response Relationship, Radiation; Electrons; Materials Testing; Membranes, Artificial; near-edge X-ray absorption fine structure; Radiation Dosage; self-assembled monolayer; Silanes - chemistry; Silanes - radiation effects; Space life sciences; synchrotron X-ray; X-ray photoelectron spectroscopy
• ISSN: 0955-3002; 1362-3095
• DOI: 10.1080/09553002.2016.1179812

Purpose: 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. Materials and methods: 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. Results: 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. Conclusions: 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.