Publications by authors named "Takuya Yokokita"

At, an α-particle emitter, has recently attracted attention for radioimmunotherapy of intractable cancers. However, our sodium dodecyl sulfate polyacrylamide gel electrophoresis and flow cytometry analyses revealed that At-labeled immunoconjugates are easily disrupted. Luminol assay revealed that reactive oxygen species generated from radiolysis of water caused the disruption of At-labeled immunoconjugates.

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Tissue factor (TF), the trigger protein of the extrinsic blood coagulation cascade, is abundantly expressed in various cancers including gastric cancer. Anti-TF monoclonal antibodies (mAbs) capable of targeting cancers have been successfully applied to armed antibodies such as antibody-drug conjugates (ADCs) and molecular imaging probes. We prepared an anti-TF mAb, clone 1084, labeled with astatine-211 ( At), as a promising alpha emitter for cancer treatment.

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Article Synopsis
  • All superheavy elements (SHEs) have been created one atom at a time, and their chemical properties remain largely unexplored due to their short lifetimes and low production rates.
  • Researchers examined the precipitation properties of Rf (Z=104) by using a co-precipitation method with samarium hydroxide, focusing on its behavior in basic solutions with NH or NaOH.
  • The study found that Rf does not strongly coordinate with NH but forms a hydroxide precipitate, likely Rf(OH), and comparisons were made with lighter homologues Zr and Hf, as well as pseudo-homologue Th.
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Article Synopsis
  • The metastable first excited state of thorium-229 is only a few electronvolts above its nuclear ground state and can be manipulated using vacuum ultraviolet lasers.
  • Researchers have achieved optical pumping into thorium using synchrotron radiation, allowing them to accurately determine the resonance energy and measure the isomer's half-life.
  • New measurements help clarify the energy of the Th isomer and improve our understanding of its nuclear structure, with potential applications in fundamental physics and the development of a nuclear clock.
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A gas-phase chemical study of rhenium carbonyls was carried out using short-lived radioisotopes produced at a heavy-ion accelerator. The Re isotopes produced in the nuclear reactions of natGd(23Na,xn)172-177Re were pre-separated with a gas-filled recoil ion separator and their carbonyls were synthesized in a mixture of inert gas and carbon monoxide. Using a low temperature isothermal chromatography apparatus, the adsorption enthalpies of Re carbonyls were derived to be ΔHads = -42 ± 2 kJ mol-1 on a Teflon® surface by fitting the external chromatograms with a Monte Carlo simulation program.

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α-Emission radiotherapeutics has potential to be one of most effective cancer therapeutics. Herein, we report a facile synthesis of an At-labeled immunoconjugate for use as an α-emission molecular targeting therapy. We synthesized a tetrazine probe modified with -decaborate(2-), a prosthetic group that forms a bioavailable stable complex with At.

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We successfully observed the equilibrium state of the chemical reactions for superheavy elements on a one-atom-at-a-time scale; we investigated the time dependence of the extraction behaviour of element 104, Rf. The distribution coefficient of Rf in 9 M HCl was found to be higher than those of its homologous elements, probably due to differences in the chloride complexation of Rf.

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To establish a new methodology for superheavy element chemistry, the coprecipitation behaviors of 34 elements with samarium hydroxide were investigated using multitracer produced by a spallation of Ta. The chemical reactions were rapidly equilibrated within 10s for many elements. In addition, these elements exhibited individual coprecipitation behaviors, and the behaviors were qualitatively related to their hydroxide precipitation behaviors.

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