On-chip erythrocyte deformability test under optical pressure

This paper presents a novel method for an on-chip erythrocyte deformability test under optical pressure, especially to enhance the level of sensitivity with respect to the detection of cancerous diseases. To demonstrate the performance and sensitivity of the combined method, we introduce the concept of transit velocity, a modified elongation index, and shape recovery time of individual erythrocytes in a strictly confined region (2 microm deep, 4 microm wide, and 100 microm long). Finally, we investigate a synergy or convergence effect due to the combination of these parameters for in situ detection of cancerous diseases under optical pressure.     

Reductive heterocyclizations via indium-iodine-promoted conversion of 2-nitroaryl imines or 2-nitroarenes to 2,3-diaryl-substituted indazoles

While N-(2-nitrobenzylidene)anilines produced mixtures of 2,1-benzisoxazoles and 3-anilino-2-aryl-2H-indazoles in the presence of indium and iodine in MeOH, N-(2-nitrobenzylidene)anilines were transformed into 3-anilino-2-aryl-2H-indazoles as the predominant major product through the change of the solvent from protic MeOH to aprotic THF. In an indium-mediated one-pot reductive reaction, 2-benzaldehydes and anilines in THF were also successfully transformed into the corresponding indazoles.     

Dynamical characteristics of bacteria clustering by self-generated attractants

Motivated by the recent work on Escherichia coli bacteria clustering [Park, S., Wolanin, P.M., Yuzbashyan, E.A., Lin, H., Darnton, N.C., Stock, J.B., Silberzan, P., Austin, R., 2003. Proc. Natl. Acad. Sci. U.S.A. 100 (24), 13910], we have conducted a computer simulation of E. coli chemotaxis induced by a self-excreted attractant and investigated how bacteria clusters interact through a self-excreted attractant. By modeling the variation of tumbling frequency in the context of phosphorylation rate change, we have investigated the dependency of clustering behavior on the sensitivity of cells to the attractant. We have found that there exists an optimal sensitivity leading to bigger clusters and that the geometry surrounding the cells also plays an important role in localizing the cluster formation. This result suggests that bacterial cluster formation can be reduced by making bacteria more sensitive to attractants, which is opposite to an instinctive way (making them retarded to attractants). In addition, we have studied the effect of an initial cell distribution on clustering.     

Polymeric chiral phase-transfer catalysts derived from cinchona alkaloids for enantioselective synthesis of α-amino acids

A series of dimeric/trimeric chiral quaternary ammonium salts derived from cinchona alkaloids were designed as efficient and practical chiral phase-transfer catalysts (PTCs). Presented are the details on the development of the dimeric PTCs for the synthesis of optically active α-amino acid derivatives and the optimization of the reaction variables suitable for the dimeric PTCs. The 1,3-phenyl- and the 2,7-naphthyl-linked dimeric PTCs showed excellent catalytic capability on the reactivity and enantioselectivity in the catalytic phase-transfer alkylation of N-(diphenylmethylene)glycine tert-butyl ester (1). A variety of α-amino acid derivatives were obtained with high enantiopurities using the dimeric PTCs, especially the 2,7-naphthyl-dimer 41, in a very practical manner.     

TBSOTf-assisted three component coupling of epoxides, THF, and ylides derived from the phosphoniosilylation products of enones and α,β-unsaturated lactones

Ylides 3, derived from the phosphoniosilylation products of enones and α,β-unsaturated lactones, were reacted with epoxides 4 and TBSOTf in THF. Interestingly, the three component coupling products 5-8 were obtained after subsequent desilylation.     

Azobenzene coupled chromogenic receptors for the selective detection of copper(II) and its application as a chemosensor kit

Azobenzene-based receptors 1-4 as colorimetric sensing materials were synthesized and their sensing properties were examined. In solution, the proposed sensing materials give rise to a large cation-induced hypochromic shift for Cu²⁺ resulting in a change from red to pale-yellow, whereas no significant color change was observed upon addition of other selected metal ions. The use of the silica gel plate modified with immobilization of receptor 4 to detect Cu²⁺ was also reported.     

Rhodamine urea derivatives as fluorescent chemosensors for Hg

New rhodamine derivatives bearing urea group have been synthesized for the detection of metal ions. Especially, the dimeric system 2 displayed a selective fluorescent enhancement and colorimetric change upon the addition of Hg²⁺, in which the spirolactam (nonfluorescent) to ring opened amide (fluorescent) process was utilized. The association constant of 2 with Hg²⁺ was calculated as 3.2 × 10⁵ M⁻¹.     

Ultrahigh-pressure dual online solid phase extraction/capillary reverse-phase liquid chromatography/tandem mass spectrometry (DO-SPE/cRPLC/MS/MS): a versatile separation platform for high-throughput and highly sensitive proteomic analyses

Capillary RPLC/ESI-MS (cRPLC/ESI-MS) is one of the most powerful analytical tools for current proteomic research. The development of cRPLC techniques coupled online to a mass spectrometer has focused on increasing the separation efficiency, detection sensitivity, and throughput. Recently, the use of high-pressure (over 10,000 psi) LC systems that utilize long, small inner diameter capillary columns has gained much attention for proteomic analyses. In this study, we developed an ultrahigh-pressure dual online SPE/capillary RPLC (DO-SPE/cRPLC) system. This LC system employs two online SPE columns and two capillary columns (75 microm inner diameter x 1 m length) in a single separation system, and has a maximum operating pressure of 10,000 psi. This DO-SPE/cRPLC system is capable of providing high-resolution separation in addition to several other advantageous features, such as high reproducibility in terms of the LC retention time, rapid sample injection, online desalting, online sample enrichment of dilute samples, and increased throughput as a result of essentially removing the column equilibration time between successive experiments. We coupled the DO-SPE/cRPLC system online to a tandem mass spectrometer to allow high-throughput proteomic analyses. In this paper, we demonstrate the efficiency of this DO-SPE/cRPLC/MS/MS system by its use in the analyses of proteomic samples exhibiting different levels of complexity.