The formation of isomeric pair in the natTi(3He,x)44m,gSc reactions: Effect of spin cut-off parameter on the isomeric ratio

Excitation functions for the natTi(3He, x)44g,mSc nuclear reactions were measured from respective threshold up to 55 MeV by using a conventional stacked-foil activation technique combined with HPGe γ-ray spectroscopy. Individual cross-section values for the production of 44mSc and 44gSc were separated using a proper mathematical method on the basis of their individual gamma lines and the data for 44gSc are reported here for the first time. The default parameters of TALYS-1.8 are unable to provide the 44mSc/44gSc isomeric cross-section ratio values consistent with those obtained experimentally. However, an adjustment of the level density model and optical model potentials together with some other relevant parameters, especially the spin cut-off parameter with the variation of η (=Ieff/Irigid) were found to be effective to reproduce the measured cross-sections. A similar parameter adjustment could be useful for accurate prediction of other medium mass isomeric pairs (i.e., when the metastable state is longer-lived than the ground state) where either experimental data are not available, or an expensive experiment is required to obtain them

Development of radio-Pt-based agents for targeted Auger electron therapy ~from radionuclide production to radio-labeling and biological evaluation

Recently, targeted radionuclide therapy (TRT) with radionuclide-derived short-range radiation has been growing rapidly. Due to their nano-scale range (2–500 nm), Auger electrons (Auger e−) have the potential to induce physiochemical damage to biomolecules smaller than a single cell, meaning that it is necessary to transport Auger e−-emitting radiopharmaceuticals to cellular regions that are sensitive to Auger e−. DNA is a prime target of Auger e− TRT; however, proper drug design has remained elusive. The DNA-damaging effect of Auger e− is maximized by an efficient interaction with DNA when Auger e− emitters are as close as possible to DNA. In this regard, radio-Pt is suitable for Auger e− TRT targeting DNA efficiently because of the unique DNA-binding ability of Pt. We have established a novel production method of no-carrier–added radio-Pt (n.c.a. 191Pt emitting Auger electrons) and developed labeling methods for n.c.a. 191Pt. In this presentation, I will introduce the series of research on 191Pt from the development of 191Pt-labeled agents to their biological evaluation.On the Horizon: Novel Isotopes and Future Leader

Development of Radio-Pt-labeled Agents Targeting DNA for Auger Electron Therapy

Recently, targeted radionuclide therapy (TRT) with radionuclide-derived short-range radiation has been growing rapidly. Due to their nano-scale range (2–500 nm), Auger electrons (Auger e−) have the potential to induce physiochemical damage to biomolecules smaller than a single cell, meaning that it is necessary to transport Auger e−-emitting radiopharmaceuticals to cellular regions that are sensitive to Auger e−. DNA is a prime target of Auger e− TRT; however, proper drug design has remained elusive. The DNA-damaging effect of Auger e− is maximized by an efficient interaction with DNA when Auger e− emitters are as close as possible to DNA. In this regard, radio-Pt is suitable for Auger e− TRT targeting DNA efficiently because of the unique DNA-binding ability of Pt. We have established a novel production method of no-carrier–added radio-Pt (n.c.a. 191Pt emitting Auger electrons) and developed labeling methods for n.c.a. 191Pt. In this presentation, I will introduce the series of research on 191Pt from the development of 191Pt-labeled agents to their biological evaluation.第２回　GSD/GI-CoRE国際シンポジウ

Transition-metal-free Nucleophilic 211At-astatination of Spirocyclic Aryliodonium Ylides

The transition-metal-free At-211-astatination of spirocyclic aryliodonium ylides via a nucleophilic aromatic substitution reaction is described. This method enables the preparation of At-211-radiolabeled compounds derived from multi-functionalized molecules and heteroarenes in good to excellent radiochemical yields

Production of 191Pt from an iridium target by vertical beam irradiation and simultaneous alkali fusion

We have developed a new method for producing 191Pt from an iridium target. Alkali fusion of iridium was successfully performed using a vertical beam irradiation method and a mixed target of Ir and Na2O2, which resulted in easy dissolution of the irradiated iridium target. A trace amount of PtⅣCl62- was isolated from bulk IrⅣCl62- by solvent extraction and anion exchange chromatography. The production yield of 191Pt was 7.1 ± 0.4 (MBq/μA h, EOB) by proton irradiation at 30 MeV. The radioplatinum product (n.c.a.) was prepared at a radiochemical purity of 97% for PtⅣCl62-, and 95% for PtⅡCl42-, respectively

Synthesis of no-carrier-added [188, 189, 191Pt]cisplatin from a cyclotron produced 188, 189, 191PtCl42- complex

We developed a novel method for production of no-carrier-added (n.c.a.) [188, 189, 191Pt]PtⅡCl42- from an Ir target material, and then synthesized n.c.a. [*Pt]cis-[PtⅡCl2(NH3)2] ([*Pt]cisplatin) from [*Pt]PtⅡCl42-. [*Pt]PtⅡCl42- was prepared as a synthetic precursor of n.c.a. *Pt complex by a combination of resin extraction and anion-exchange chromatography after the selective reduction of IrⅣCl62- with ascorbic acid. The ligand-substitution reaction of Cl with NH3 was promoted by treating n.c.a. [*Pt]PtⅡCl42- with excess NH3 and heating the reaction mixture, and n.c.a. [*Pt]cisplatin was successfully produced without employing precipitation routes. After this treatment, [*Pt]cisplatin was isolated through preparative HPLC with a radiochemical purity of 99+% at the end of synthesis (EOS)