Chiya Numako

Formation mechanism of TiO2-derived titanate nanotubes prepared by the hydrothermal process.

The structural change on the molecular scale of anatase-type TiO(2) during hydrothermal treatment was investigated in detail by various analytic techniques such as X-ray absorption fine structure and transmission electron microscopy in order to clarify the formation mechanisms of titanate-based nanotubes. It revealed that the nanosheet-like products composed of highly distorted TiO(6) octahedra were generated by hydrothermal treatment of anatase-type TiO(2), and then the anatase-like structures are partially built up with the formative nanotubes by scrolling up these nanosheet-like products and nanosheets.

TiO2-Derived Titanate Nanotubes by Hydrothermal Process with Acid Treatments and Their Microstructural Evaluation

In this study, the effect of post acid treatments with HCl aqueous solutions after the hydrothermal process on the microstructure of TiO2-derived titanate nanotube was investigated. Especially, the relationship between local structural changes with the HCl treatment and their thermal stability were investigated by X-ray absorption fine structure (XAFS). Consequently, it revealed that the replacement of Na+ with H+ (proton exchange) in TiO2-derived titanate nanotubes was caused by the acid treatment with HCl aqueous solutions and the excess acid treatment led to the disordering. Moreover, it was confirmed that the minor change of TiOx polyhedra in TiO2-derived titanate nanotubes was also related with this disordering.

Particle size for photocatalytic activity of anatase TiO2 nanosheets with highly exposed {001} facets

Size-controllable TiO2 nanosheets with highly exposed {001} facets were synthesized by a hydrothermal method. The particle sizes ranged from 25 nm to submicrometres by carefully adjusting the F/Ti molar ratio. TiO2 nanosheets smaller than 100 nm have higher photocatalytic activity and are highly stable in degradation of organic dyes.

Preparation and characterization of Silicalite-1 zeolites with high manganese contents from mechanochemically pretreated reactants

Silicalite-1 zeolites with high manganese contents isomorphously incorporated within the framework were synthesized by using mechanochemical pretreatment. First, manganese and silica sources were mixed in a planetary ball mill to obtain a composite material comprised of Mn, Si, and O. The composite was subsequently hydrothermally treated to crystallize Silicalite-1 zeolites. The synthesis was performed using a condition with a small amount of water to directly convert the composite material into a zeolite crystal while preventing manganese from leaching into water, which may cause manganese oxide/hydroxide species to precipitate. X-ray fluorescence analysis showed that the obtained products displayed a high manganese content of up to 6.3 mol%. The importance of utilizing mechanochemical treatment was confirmed through a number of characterization techniques, such as X-ray diffraction, catalytic activity assessments, diffuse reflectance UV-vis spectroscopy, Raman spectroscopy, and X-ray absorption fine structure analysis. Our findings suggest that this procedure using mechanochemical pretreatment can produce zeolites with various heteroatoms within their framework structures at contents difficult to achieve through conventional methods.

Detection of trace metallic elements in oral lichenoid contact lesions using SR-XRF, PIXE, and XAFS

Oral lichen planus (OLP) and oral lichenoid contact lesions (OLCL) are chronic inflammatory mucocutaneous reactions with a risk of malignant transformation that alter the epithelium. OLP and OLCL have similar clinical and histopathological features and it is difficult to distinguish one from the other. Metallic restorations are suspected to generate OLCLs. Trace metal analysis of OLCL specimens may facilitate the discrimination of symptoms and identification of causative metallic restorations. The purpose of this study was to assess OLCL tissue samples for the prevalence of metallic elements derived from dental restorations, and to discriminate OLCL from OLP by using synchrotron radiation-excited X-ray fluorescence analysis (SR-XRF), particle-induced X-ray emission (PIXE), and X-ray absorption fine structure (XAFS). Typical elements of dental materials were detected in the OLCL, whereas no obvious element accumulation was detected in OLP and negative control specimens. The origin of the detected metallic elements was presumed to be dental alloys through erosion. Therefore, our findings support the feasibility of providing supporting information to distinguish OLCL from OLP by using elemental analysis.

Characterization of titanium dioxide nanoparticles modified with polyacrylic acid and H2O2 for use as a novel radiosensitizer

Abstract An induction of polyacrylic acid-modified titanium dioxide with hydrogen peroxide nanoparticles (PAA-TiO2/H2O2 NPs) to a tumor exerted a therapeutic enhancement of X-ray irradiation in our previous study. To understand the mechanism of the radiosensitizing effect of PAA-TiO2/H2O2 NPs, analytical observations that included DLS, FE-SEM, FT-IR, XAFS, and Raman spectrometry were performed. In addition, highly reactive oxygen species (hROS) which PAA-TiO2/H2O2 NPs produced with X-ray irradiation were quantified by using a chemiluminescence method and a EPR spin-trapping method. We found that PAA-TiO2/H2O2 NPs have almost the same characteristics as PAA-TiO2. Surprisingly, there were no significant differences in hROS generation. However, the existence of H2O2 was confirmed in PAA-TiO2/H2O2 NPs, because spontaneous hROS production was observed w/o X-ray irradiation. In addition, PAA-TiO2/H2O2 NPs had a curious characteristic whereby they absorbed H2O2 molecules and released them gradually into a liquid phase. Based on these results, the H2O2 was continuously released from PAA-TiO2/H2O2 NPs, and then released H2O2 assumed to be functioned indirectly as a radiosensitizing factor.

Uranium XAFS analysis of kidney from rats exposed to uranium

Characterization of uranium accumulated in the micro-regions of renal tubules of rats exposed to uranyl acetate was examined by micro-X-ray absorption fine-structure analysis and the results showed the possible biotransformation of uranium in this in vivo system.

Quenching ilmenite with a high-temperature and high-pressure phase using super-high-energy ball milling

The mass production of highly dense oxides with high-temperature and high-pressure phases allows us to discover functional properties that have never been developed. To date, the quenching of highly dense materials at the gramme-level at ambient atmosphere has never been achieved. Here, we provide evidence of the formation of orthorhombic Fe2TiO4 from trigonal FeTiO3 as a result of the high-temperature (>1250 K) and high-pressure (>23 GPa) condition induced by the high collision energy of 150 gravity generated between steel balls. Ilmenite was steeply quenched by the surrounding atmosphere, when iron-rich ilmenite (Fe2TiO4) with a high-temperature and high-pressure phase was formed by planetary collisions and was released from the collision points between the balls. Our finding allows us to infer that such intense planetary collisions induced by high-energy ball milling contribute to the mass production of a high-temperature and high-pressure phase.

Abstract 3337: Titanium peroxide nanoparticles enhance antitumor efficacy through reactive oxygen species in pancreatic cancer radiation therapy

Purpose: Pancreatic cancer is a highly lethal disease and notoriously resistant to many types of cytotoxic chemotherapy and radiotherapy. A novel strategy should be explored for these radioresistant tumors. We originally synthesized a titanium peroxide nanoparticle (TiOxNP) which had a distinct ability to produce reactive oxygen species (ROS) upon X-ray irradiation (IR). Here, the characterization and efficacy of TiOxNP as radiosensitizer for pancreatic cancer therapy were investigated. Methods: TiOxNPs were synthesized from anatase titanium oxide nanoparticles (TiO2NPs) by H2O2 processing and coated by polyacrylic acid. The ability of TiOxNPs to enhance ROS generation upon X-ray irradiation (IR) was tested by using 3′-(p-Aminophenyl) fluorescein and several antioxidants. A xenograft mouse model using the human pancreatic cancer cell line MIAPaCa-2 was used to evaluate the cytotoxic effects of a combination of TiOxNPs and IR in vivo. MIAPaCa-2 cells were injected subcutaneously into the hind legs of immunodeficient BALB/c mice. Seven days after injection, the tumor was treated with a TiOxNP suspension injected directly into the tumor and application of 5 Gy of IR. Tumor size and health of the mice were monitored for 43 days after the treatment. Induction of apoptosis was evaluated by immunohistochemistry using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling staining. We also characterized TiOxNPs by ESR and XAFS analyses. Results: ROS generation was enhanced dramatically by TiOxNPs in a concentration- and radiation dose- dependent manner compared to enhancement by TiO2NPs. At the highest concentration of TiOxNPs, ROS generation upon an irradiation dose of 30 Gy was enhanced by a factor of more than 10. Also, ROS generated by TiOxNPs upon IR were scavenged by vitamin C or glutathione. Growth inhibition of the tumor in the group receiving both TiOxNP and IR was significantly greater than single treatment subgroups (P Conclusions: TiOxNPs induced remarkable ROS production upon IR. They were safe and effective in a xenograft mouse model using engrafted human pancreatic cancer cells. Further studies would be necessary to elucidate a mechanism of radical generation and long-term toxicity, however our study shows that TiOxNPs are promising radiosensitizers for application in pancreatic cancer therapy. Citation Format: Masao Nakayama, Ryohei Sasaki, Toru Mukohara, Chiaki Ogino, Kenta Morita, Mitsuo Umetsu, Satoshi Ohara, Kazuyoshi Sato, Chiya Numako, Seiichi Takami, Akihiko Kondo. Titanium peroxide nanoparticles enhance antitumor efficacy through reactive oxygen species in pancreatic cancer radiation therapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3337. doi:10.1158/1538-7445.AM2015-3337