We have developed an electrochemical biologic small molecule sensor that can detect superoxide anion radicals (O2−•) and nitric oxide (NO). The dual O2−•/NO sensor was fabricated by surface modification of plastic foamed carbon (PFC) electrodes with polymerized iron tetrakis(3-thienyl)porphyrin (FeT3ThP) with 1-methylimidazole; it can detect O2−• and NO at the same time. Furthermore, we fabricated a sensor having improved selectivity by coating a Nafion® film onto the sensor. Current response at the O2−•/NO sensor exhibited good linearity in the O2−• and NO concentration ranges of 1.3–4.1 μmol L−1, and 7 nmol L–1–0.14 μmol L–1, respectively. The O2−•/NO sensor is highly versatile, because these electrodes can detect O2−• and NO by the same fabrication procedure. Since the O2−•/NO sensor contains no bio-derived compounds, it should be safe, even when it is used in vivo.
To date, chemosensors have been vigorously researched in the field of supramolecular analytical chemistry because they can read out molecular recognition phenomena as visible optical changes. However, the synthesis of highly selective receptors, such as antibodies and enzymes, is not amenable, which might prevent the popularity of artificial receptors for use in practical analytical assessments. In that regard, an “array of chemosensors” can offer a high-throughput, accurate and simultaneous detections of multi-analytes, because the cross-reactivity of chemosensors is suitable to obtain information-rich data for pattern-recognition analysis. The problem of a high synthetic effort for a number of chemosensors for an array, however, still remains. Toward that end, we attempted to achieve multi-analyte detection using only a small number of chemosensors. In other words, the employment of intramolecular and/or intermolecular interactions for the fabrication of sensor arrays is a powerful method to simplify the sensing system. Because simpler arrays using intramolecular/intermolecular interactions can detect various types of analytes, even in biological fluids, our proposed systems of supramolecular sensors will be valuable tools in many fields in the near future.
Although non-coding small RNAs were believed to be non-functional “junk” in the genome, recent studies have now highlighted their key roles in regulating gene expression in various biological processes. In this paper, we describe the current methods for analysis of microRNAs and small interfering RNAs (siRNAs), representatives of small RNAs, including our approaches based on RNA-binding fluorescent probes.
We are pursuring research on an analytical method for measuring multiple organic compounds that combines quantitative nuclear magnetic resonance spectroscopy (qNMR) and chromatography. Combining qNMR and chromatography provides two advantages: qNMR that reference materials corresponding to each analyte are not required, and that this method can measure concentrations in multi-component solutions in which signals overlap each other in qNMR. In this study, this method was applied to measure the concentration of non-ionic surfactant standard solutions that are difficult to measure in isolation by 1H qNMR alone because of usually contain impurities, such as similar components of different chain lengths. However, heptaoxyethylene dodecyl ether, which was used in this study as one of the non-ionic surfactants, had no characteristic absorption in the ultraviolet wavelength band for which ultraviolet adsorption detectors was widely used, so the vacuum ultraviolet band was adopted to detect heptaoxyethylene dodecyl ether. In addition, a refractive-index detector was used in tandem with an ultraviolet adsorption detector to verify the measured values. By using this method, a certified reference material of 1000 mg L−1 of heptaoxyethylene dodecyl ether standard solution was measured. As a result, measurements could be performed with a relative expanded uncertainty of 1.5 % (k = 2); the obtained concentration matches the certified value.
Tokakujokito is a Kampo medicine for women’s illnesses (e.g., menstrual pain and menstrual irregularity). The Japanese Pharmacopoeia lists it as a Kampo formula that is composed of Persicae semen, Cinnamomi cortex, Rhei rhizoma, Glycyrrhizae radix, and sal mirabilis. Two methods for identifying the Cinnamomi cortex in Tokakujokito Extract are available. One involves simple extraction, while the other requires complicated, laborious extraction. In order to simplify selection for identification, we investigated whether an assay for (E)-cinnamic acid could be used. We discovered that the Cinnamomi cortex could be identified by the presence or absence of a peak for (E)-2-methoxycinnamaldehyde in the HPLC chromatogram. This method will make identification of the Cinnamomi cortex easy, which may greatly contribute to the efficiency of testing Tokakujokito Extracts in the future.
Sakata lagoon, a sand-dammed dune lake fed by only spring water and precipitation, is located in Niigata City. The inflow water from the upper lagoon, Kami-sakata, and the outflow water to the general river, were collected biweekly 152 times over a period ranging from February 2011 to January 2017, respectively. The total arsenic (T-As) and other parameters (temperature, pH, ORP, main ionic components including HCO3−, iron, and manganese) were measured. Based on the temporal variations, seasonal comparisons and factor analysis, the following conclusions were obtained: 1) The concentration of T-As increased in the warm season, and sometimes exceeded the environmental standard value of 10 μg L−1. Approximately, 80 % of the T-As is present in the soluble form. 2) The ORP of outflow water decreased during the warm seasons to approximately 86 % of that during the cold seasons. Further, during warm seasons, the concentrations of NO3− and SO42− significantly decreased, and the concentrations of HCO3− in both the inflow and outflow water remarkably increase during warm season. 3) The increase in the concentration of T-As during the warm season is considered to be caused by the reduced adsorption affinity of As onto the organic matter and/or Fe(III) hydroxide in the lake sediments. Biological activities in the sediments may induce the decomposition of organic matter and a decreased ORP; the increased concentration of HCO3− and pH occurred mainly in outflow water, which affords the following decreased adsorption affinity of As.
Terahertz spectroscopy enables to detect relative weak energy such as hydrogen bonding and intermolecular vibration. Therefore it is possible to identify the crystalline state of some material, such as quality of a crystal, and polymorphism. However, quantitative analyses have not been achieved in terahertz spectroscopy since an influence involving the scattering of terahertz waves is unavoidable. Only a few papers reported on quantitative analysis. In this study, we intend to establish a method for quantitative and high sensitive determination of a component from the mixed samples using pretreatment and a principal component analysis of terahertz spectra.