Akihiko Ishida

The combination of a microfluidic paper-based analytical device (μPAD) and digital image analysis is widely used for quantitative analysis with μPADs because of its easy and simple operation. Herein, we have demonstrated a quantitative analysis based on multiple color changes on a μPAD. The CIE L*a*b* color system was employed to analyse the digital images obtained with the μPAD. We made pH measurements using a universal pH-indicator showing multiple color changes for various pH values of aqueou

Abstract Dienoxysilanes (2) react with acetals in the presence of TiCl4 and also in the coexistence of TiCl4 and Ti(OiPr)4 to give δ-alkoxy-α,β-unsaturated aldehydes (3–5) in good yields. In the presence of 1,8-diazabicyclo[5.4.0] undec-7-ene or 1,5-diazabicyclo[4.3.0]non-5-ene and molecular sieves 3A or 4A, the elimination reaction of δ-alkoxyl group of α,β-unsaturated aldehydes (3–5) proceeds smoothly to afford the corresponding polyenals in good yields.

Ochratoxin A (OTA) is one of the most abundant food-contaminating mycotoxins that is also a potential carcinogen and responsible for many diseases affecting humans. Consequently, a sensitive, portable device for the detection of OTA is highly desirable. In this study, a miniaturized electrochemical aptamer-based sensor was developed for the label-free, sensitive detection of OTA. For the construction of the sensor, a gold thin-film three-electrode system was fabricated using standard microfabric

Abstract Various carbonyl compounds undergo the reductive dimerization to produce symmetrical olefins in high yields on treatment with low valent titanium compounds, formed in situ from TiCl4 and LiAlH4, in the presence of a tertiary amine such as 1,8-bis(dimethylamino)-naphthalene or tri-n-butylamine. This method is successfully applied to the direct synthesis of β-carotene (6) from retinal (5).

Abstract 1-Sorboyl-2-pyrrolidone was prepared from sorbic acid and 2-ethoxy-1-pyrroline using 1-methyl-2-chloropyridinium iodide as a coupling reagent. Variotin and its analogs were similarly synthesized from lactim ethers and (2E,4E,6E)-8-hydroxy-2,4,6-dodecatrienoic acids without protecting the hydroxyl group at C-8. (2E,4E,6E)-8-Hydroxy-6-methyl-2,4,6-dodecatrienal, a precursor of trienoic acid, was synthesized by the elimination of methanol from (2E,6E)-8-acetoxy-5-methoxy-6-methyl-2,6-dodec

N-Alkylthiocarbonyltryptophan (2a-i) and tryptamine (2j-m) derivatives can be converted into the corresponding 3, 4-dihydro-β-carbolines (3) under mild conditions by the use of alkylating or acylating agents. The NaBH4 reduction of 1, 3-disubstituted 3, 4-dihydro-β-carbolines (3a-i) gave cis- (5) or trans-1, 2, 3, 4-tetrahydro-β-carbolines (6) with satisfactory stereoselectivity. The synthesis of optically active 3a, b and 5a, b is also described.

The development of low-cost, user-friendly paper-based analytical devices (PADs) that can easily measure target chemicals is attracting attention. However, most PADs require manipulation of the sample using sophisticated micropipettes for quantitative analyses, which restricts their user-friendliness. In addition, immobilization of detection molecules to cellulose fibers is essential for achieving good measuring ability as it ensures the homogeneity of color development. Here, we have described