Since disease-related marker substances in living organisms exist in extremely small amounts, the development of new analysis and evaluation techniques is required. Novel fluorescence analysis reagents have been developed and the reagents with high affinity for disease-related substances have been and immobilized on the surface of magnetic particles that facilitate B/F separation. The reagents are highly versatile in applications that require automation and high throughput, enabling highly sensitive detection of disease-related substances. In this paper, these fluorescent magnetic nanoparticles are described with an emphasis on applications from the viewpoint of analytical chemistry.

Inductively coupled plasma mass-spectrometry has been commonly applied to determine the elemental concentrations of human fingernails. However, the obtained values are averaged quantitative values and elemental distributions in the plane and depth of nail samples have not been reported. In this study, we applied micro-X-ray fluorescence analysis equipped with a capillary optic for obtaining elemental distributions in the plane of a nail sample. The results showed that S and Ca were almost homogeneously distributed, while K and Zn were confirmed to be concentrated near the tip of the fingernail. Furthermore, confocal micro-X-ray fluorescence (CMXRF) analysis was employed nondestructively to obtain elemental depth distributions. As a result of analyzing the XRF intensity distribution of Ca after correcting for the absorption of the XRF inside the nail sample, the result suggesting that Ca distributed not only near the surface of the sample but also inside the nail was obtained.

A large amount of radiocesium spread into the environment during the accident at the Fukushima Dai-ichi Nuclear Power Plant in Japan. Radiocesium entered into houses around the plant and formed radiocesium-containing indoor dust. Physical and chemical properties of radiocesium-bearing particles, such as solubility, size distribution and their radioactivity, are important for the estimation and reduction of inhalation doses from indoor dust. It is not possible to obtain samples such as ceiling boards or floor panels from inhabited houses which were potential sources of radiocesium-containing dust. Therefore, on-site measurement is required instead of sample collection. An imaging plate (IP) can be used to visualize the distribution information of radioactive substances on ceiling boards or floor panels. Information on the number density and radioactivity of substances containing radiocesium can be obtained by using IPs. The analytical conditions (selection of geometry of radiation sources, correction of signal attenuation during measurement and transport, evaluation of background radiation and so on) were optimized for the quantitative measurement using IPs in the houses under relatively high air doses. Consequently, it was shown that particles with radioactivity of about 0.1–0.7 Bq were distributed on the ceiling boards of houses under evacuation.

Biological samples such as blood and urine contain a useful information indicating the health status of individuals. Therefore, the measurement of these biomolecules is widely used to diagnose diseases. To develop a new glucagon detection method that does not rely on antibodies, we focused on the glucagon receptor. The glucagon receptor, which is the G protein-coupled receptor (GPCR), is widely expressed in whole tissue. Since the glucagon receptor recognizes glucagon with high specificity and sensitivity, we thought that using its recognition site would be suitable for creating a novel glucagon-sensing probe. In this study, glucagon-binding peptides were screened from a peptide library of about 20 residues selected from the glucagon receptor sequence. We developed a glucagon-sensing probe by modifying the glucagon-binding peptides with a fluorescent dye that increases fluorescence intensity in response to environmental conditions. Further optimizing the amino acid sequence of the probe is expected to further improve the sensitivity and specificity. In the future, the probe is expected to be applied to a diagnostic method for blood glucagon that is more specific and more easily applied than conventional methods using antibodies.