Microanalysis of silica-based adsorbent for effective recovery of radioactive elements

<p>For effective recovery of radioactive elements by adsorbents using polymer-immobilized silica (SiO₂-P) supports, the microstructure of SiO₂-P particles impregnated with octyl(phenyl)-<i>N</i>, <i>N</i>-diisobutylcarbamoylmethylphosphine oxide as extractants and their change with the crosslinking degree of polymer (CDP) were investigated using scanning transmission X-ray microscopy (STXM) and extended X-ray absorption fine structures (EXAFS) analyses; further, their relation with adsorption/elution behavior was discussed. The results of STXM analysis suggested that the polymer is distributed within several hundred nanometers of the pore surface, and its distributions are spread by the increase of CDP. In addition, the capture of impurity molecules such as H₂O by polymers with high CDP was indicated. EXAFS analyses showed that the local structure around adsorbed europium ions is similar irrespective of the CDP. The adsorption/elution tests demonstrated that a higher CDP inhibited the elution of adsorbed europium ions from the adsorbent.</p

Microscopic analyses of complexes formed in adsorbent for Mo and Zr separation chromatography

高レベル放射性廃液(HALW)の処理に於いて、抽出クロマトグラフィーによる高効率なマイナーアクチノイド(MA)の回収にはモリブデン(Mo)及びジルコニウム(Zr)の事前除去が必要である。そこで、MoとZrの除去と回収を目的としてbis(2-ethylhexyl) hydrogen phosphate (HDEHP)を含浸させた吸着材を用いることを考案し、模擬HALWのカラム分離実験で、MoとZrを選択的に吸着させて除去することに成功した。次に、吸着材からそれらを回収するための溶離液として過酸化水素水を用いたところ、Moのみ溶離された。この吸着材のマイクロPIXE、EXAFS及びX線小角散乱法による分析結果は、結晶状のZr-HDEHP複合体が吸着材中に一様に形成されたことを示していたことから、Moは今回の方法で除去・回収できるが、Zrは結合が強く、過酸化水素水では回収できないことがわかった

Extraction Mechanism of Lanthanide Ions into Silica-based Microparticles Studied by Single Microparticle Manipulation and Microspectroscopy

Single porous silica microparticles coated with a styrene-divinylbenzene polymer (SDB) impregnated with octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) were injected into an aqueous 3 mol/L nitric acid solution containing trivalent lanthanide (Ln(III)), as a high-level liquid waste model. We used the microcapillary manipulation-injection technique; and the extraction rate of Ln(III), as an Ln(III)-CMPO complex, into the single microparticles was measured by luminescence microspectroscopy. The extraction rate significantly depended on the Ln(III), CMPO, or NO3− concentration, and was analyzed in terms of diffusion in the pores of the microparticles and the complex formation of Ln(III). The results indicated that the rate-determining step in Ln(III) extraction was diffusion in the pore solution of the microparticles

Low immunogenicity of mouse induced pluripotent stem cell-derived neural stem/progenitor cells

Abstract Resolving the immunogenicity of cells derived from induced pluripotent stem cells (iPSCs) remains an important challenge for cell transplant strategies that use banked allogeneic cells. Thus, we evaluated the immunogenicity of mouse fetal neural stem/progenitor cells (fetus-NSPCs) and iPSC-derived neural stem/progenitor cells (iPSC-NSPCs) both in vitro and in vivo. Flow cytometry revealed the low expression of immunological surface antigens, and these cells survived in all mice when transplanted syngeneically into subcutaneous tissue and the spinal cord. In contrast, an allogeneic transplantation into subcutaneous tissue was rejected in all mice, and allogeneic cells transplanted into intact and injured spinal cords survived for 3 months in approximately 20% of mice. In addition, cell survival was increased after co-treatment with an immunosuppressive agent. Thus, the immunogenicity and post-transplantation immunological dynamics of iPSC-NSPCs resemble those of fetus-NSPCs

Evaluation of the immunogenicity of human iPS cell-derived neural stem/progenitor cells in vitro

To achieve the goal of a first-in-human trial for human induced pluripotent stem cell (hiPSC)-based transplantation for the treatment of various diseases, allogeneic human leukocyte antigen (HLA)-matched hiPSC cell banks represent a realistic tool from the perspective of quality control and cost performance. Furthermore, considering the limited therapeutic time-window for acute injuries, including neurotraumatic injuries, an iPS cell bank is of potential interest. However, due to the relatively immunoprivileged environment of the central nervous system, it is unclear whether HLA matching is required in hiPSC-derived neural stem/progenitor cell (hiPSC-NS/PC) transplantation for the treatment of neurodegenerative diseases and neurotraumatic injuries. In this study, we evaluated the significance of HLA matching in hiPSC-NS/PC transplantation by performing modified mixed lymphocyte reaction (MLR) assays with hiPSC-NS/PCs. Compared to fetus-derived NS/PCs, the expression levels of human leukocyte antigen-antigen D related (HLA-DR) and co-stimulatory molecules on hiPSC-NS/PCs were significantly low, even with the addition of tumor necrosis factor-α (TNFα) and/or interferon-γ (IFNγ) to mimic the inflammatory environment surrounding transplanted hiPSC-NS/PCs in injured tissues. Interestingly, both the allogeneic HLA-matched and the HLA-mismatched responses were similarly low in the modified MLR assay. Furthermore, the autologous response was also similar to the allogeneic response. hiPSC-NS/PCs suppressed the proliferative responses of allogeneic HLA-mismatched peripheral blood mononuclear cells (PBMCs) in a dose-dependent manner. Thus, the low antigen-presenting function and immunosuppressive effects of hiPSC-NS/PCs result in a depressed immune response, even in an allogeneic HLA-mismatched setting. It is crucial to verify whether these in vitro results are reproducible in a clinical setting