X-ray-Fluorescence-Based Screening Method for Uranium in Contaminated Brackish Water Using Graphene Oxide Nanosheets.

In the event of uranium release into the environment due to an accident, confirming the presence of uranium contamination is difficult because uranium is a naturally occurring element. In this study, we developed a method based on X-ray fluorescence (XRF) for the facile screening of uranium in brackish water samples in the event of an accident in a coastal area. Graphene oxide nanosheets were added to uncontaminated brackish water sampled from different sites to adsorb the uranium present in the samples, if any. The graphene oxide nanosheets were then collected using a membrane filter and analyzed using XRF. The results revealed that the signal intensity of the U Lα peak was proportional to the salinity. Hence, uranium contamination could be confirmed when the intensity of the U Lα peak was significantly greater than that derived from the background uranium content, as estimated from the salinity value. Thus, in the event of an accident, the salinity of the collected brackish water should be measured, and XRF analysis should be performed using our developed method. This method is useful for screening brackish water for uranium contamination.

Quality evaluation of cell spheroids for transplantation by monitoring oxygen consumption using an on-chip electrochemical device.

Three-dimensional cell spheroids are superior cell-administration form for cell-based therapy which generally exhibit superior functionality and long-term survival after transplantation. Here, we nondestructively measured the oxygen consumption rate of cell spheroids using an on-chip electrochemical device (OECD) and examined whether this rate can be used as a marker to estimate the quality of cell spheroids. Cell spheroids containing NanoLuc luciferase-expressing mouse mesenchymal stem cell line C3H10T1/2 (C3H10T1/2/Nluc) were prepared. Spheroids of high or low quality were prepared by altering the medium change frequency. After transplantation into mice, the high-quality C3H10T1/2/Nluc spheroids exhibited a higher survival rate than the low-quality ones. The oxygen consumption rate of the high-quality C3H10T1/2/Nluc spheroids was maintained at high levels, whereas that of the low-quality spheroids decreased with time. These results indicate that OECD-based measurement of the oxygen consumption rate can be used to estimate the quality of cell spheroids without destructive analysis of the spheroids.

Rapid detection of plutonium contamination with and without uranium contamination in wounds by x-ray fluorescence.

In the event of an accident at a nuclear fuel handling facility, the wounds of affected workers may be contaminated with plutonium. The current approach for identifying plutonium contamination is by detecting α-particles in the blood stream. However, the applicability of this approach is impeded due to the α-particles being easily shielded by the bodily fluid components. In this study, we investigate a contamination testing method for such cases that involves the collection of blood with a small piece of filter paper, sealing the sample with thin films, and performing x-ray fluorescence analysis. Our previous study on collecting uranium-contaminated blood with filter paper and performing x-ray fluorescence analysis revealed that the effects arising from blood components could be completely removed by peak fitting, and thus water instead of blood was used as a solvent here. Samples containing various amounts of plutonium as well as samples with 150 Bq of plutonium and uranium were prepared with a mass ratio of 0 to 500 times greater than that of plutonium. x-ray fluorescence measurements showed a high linearity and reproducibility of the Pu Lα peak intensity and plutonium radioactivity, and it was clarified that the signal intensity of the Pu Lα peak did not depend on the amount of coexisting uranium. This method will allow for the simple and rapid assessment of plutonium contamination in wounds.