Catalytic Enantioselective Reaction of α‐Phenylthioacetonitriles with Imines Using Chiral Bis(imidazoline)–Palladium Catalysts

The catalytic enantioselective reaction of α‐phenylthioacetonitriles with imines has been developed. The reaction of various imines proceeds in good yields and diastereo‐ and enantioselectivities in the presence of chiral bis(imidazoline)–palladium catalysts. The obtained products can be converted into β‐aminonitrile or β‐aminoamide compounds without loss of enantiopurity.     

Laplace transform impedance analysis in the two-phase coexistence reaction of spinel Li1 + x Mn2O4 positive electrode

Journal of Solid State Electrochemistry - We demonstrate the Laplace transform (LT) impedance technique for measuring electrochemical lithiation and delithiation in the two-phase system of spinel...     

Influence of biological media on the structure and behavior of ferrocene-containing cationic lipid/DNA complexes used for DNA delivery

Biological media affect the physicochemical properties of cationic lipid-DNA complexes (lipoplexes) and can influence their ability to transfect cells. To develop new lipids for efficient DNA delivery, the influence of serum-containing media on the structures and properties of the resulting lipoplexes must be understood. To date, however, a clear and general picture of how serum-containing media influences the structures of lipoplexes has not been established. Some studies suggest that serum can disintegrate lipoplexes formed using certain types of cationic lipids, resulting in the inhibition of transfection. Other studies have demonstrated that lipoplexes formulated from other lipids are stable in the presence of serum and are able to transfect cells efficiently. In this article, we describe the influence of serum-containing media on lipoplexes formed using the redox-active cationic lipid bis(n-ferrocenylundecyl)dimethylammonium bromide (BFDMA). This lipoplex system promotes markedly decreased levels of transgene expression in COS-7 cells as serum concentrations are increased from 0 to 2, 5, 10, and 50% (v/v). To understand the cause of this decrease in transfection efficiency, we used cryogenic transmission electron microscopy (cryo-TEM) and measurements of zeta potential to characterize lipoplexes in cell culture media supplemented with 0, 2, 5, 10, and 50% serum. Cryo-TEM revealed that in serum-free media BFDMA lipoplexes form onionlike, multilamellar nanostructures. However, the presence of serum in the media caused disassociation of the intact multilamellar lipoplexes. At low serum concentrations (2 and 5%), DNA threads appeared to separate from the complex, leaving the nanostructure of the lipoplexes disrupted. At higher serum concentration (10%), disassociation increased and bundles of multilamellae were discharged from the main multilamellar complex. In contrast, lipoplexes characterized in serum-free aqueous salt (Li(2)SO(4)) medium and in OptiMEM cell culture medium (no serum) did not exhibit significant structural changes. The zeta potentials of lipoplexes in serum-free media (salt medium and cell culture medium) were similar (e.g., approximately -35 mV). Interestingly, the presence of serum caused the zeta potentials to become less negative (about -20 mV in OptiMEM and -10 mV in Li(2)SO(4)), even though serum contains negatively charged entities that have been demonstrated to lead to more negative zeta potentials in other lipoplex systems. The combined measurements of zeta potential and cryo-TEM are consistent with the proposition that DNA threads separate from the lipoplex in the presence of serum, resulting in a decrease in the net negative charge of the surface of the lipoplex.     

Anti-biofouling properties of an amphoteric polymer brush constructed on a glass substrate

An amphoteric copolymer brush of methacrylic acid (MA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) was prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization using both a free chain transfer agent (n-butylsulfanylthiocarbonylsulfanyl-2-methyl propionic acid) and a radical initiator (4,4'-azobis(4-cyanopentanoic acid)) covalently fixed to a glass substrate. An aqueous solution of the copolymer, Poly(MA-r-DMAEMA), which was simultaneously obtained in liquid phase, had a sufficiently small polydispersity in its molecular weight. The copolymer brush showed effective suppression of non-specific adsorption of bovine serum albumin and egg white lysozyme to the brush. In contrast, both negatively charged PolyMA and positively charged PolyDMAEMA brushes significantly adsorbed the proteins irrespective of their net charges. Upon ion beam irradiation, furthermore, a hollow space with a designed shape could be made on the glass substrate, and both HEK293 and HepG2 cells non-specifically adhered to the space, forming aggregates, while no adhesion to the non-treated area on the brush was observed. These results suggest that the amphoteric polymer brushes will be useful materials for biomedical applications.     

Nb2O5·nH2O as a heterogeneous catalyst with water-tolerant Lewis acid sites

Niobic acid, Nb(2)O(5)·nH(2)O, has been studied as a heterogeneous Lewis acid catalyst. NbO(4) tetrahedra, Lewis acid sites, on Nb(2)O(5)·nH(2)O surface immediately form NbO(4)-H(2)O adducts in the presence of water. However, a part of the adducts can still function as effective Lewis acid sites, catalyzing the allylation of benzaldehyde with tetraallyl tin and the conversion of glucose into 5-(hydroxymethyl)furfural in water.     

MOF-on-MOF heteroepitaxy: perfectly oriented [Zn2(ndc)2(dabco)]n grown on [Cu2(ndc)2(dabco)]n thin films

We report the successful heteroepitaxial growth of perfectly oriented hybrid MOF thin films. By employing step-by-step liquid-phase epitaxy (LPE), [Zn(2)(ndc)(2)(dabco)](n) was grown on [Cu(2)(ndc)(2)(dabco)](n), thus demonstrating that the MOF-on-MOF deposition scheme developed for powdered microcrystalline MOF materials can also be applied in connection with LPE for MOF thin films or multilayers. The deposition was monitored by surface plasmon resonance (SPR) spectroscopy, the resulting MOF heterostructures were characterized using IR spectroscopy and different types of X-ray diffraction (XRD)-based techniques. The results suggest that the LPE method is a promising way to fabricate and grow MOF heterostructures, and also demonstrates the potential of [Cu(2)(ndc)(2)(dabco)](n) MOF thin films as substrates for the LPE-based growth of different MOFs on top.     

Derivative spectrum chromatographic method for the determination of trimethoprim in honey samples using an on-line solid-phase extraction technique

A simple, selective and rapid analytical method for determination of trimethoprim (TMP) in honey samples was developed and validated. This method is based on a SPE technique followed by HPLC with photodiode array detection. After dilution and filtration, aliquots of 500 μL honey samples were directly injected to an on-line SPE HPLC system. TMP was extracted on an RP SPE column, and separated on a hydrophilic interaction chromatography column during HPLC analysis. At the first detection step, the noise level of the photodiode array data was reduced with two-dimensional equalizer filtering, and then the smoothed data were subjected to derivative spectrum chromatography. On the second-derivative chromatogram at 254 nm, the limit of detection and the limit of quantification of TMP in a honey sample were 5 and 10 ng/g, respectively. The proposed method showed high accuracy (60-103%) with adequate sensitivity for TMP monitoring in honey samples.     

Image printing on the surface of anti-biofouling zwitterionic polymer brushes by ion beam irradiation

A CMB monomer was polymerized on a glass plate with a surface-confined ATRP initiator containing a 2-bromoisobutyryl group. The glass plate modified with a PCMB brush was highly hydrophilic and showed a strong resistance against non-specific adsorption of proteins and cell adhesion. Upon ion beam irradiation, furthermore, the PCMB brush was ablated and a hollow space with a designed shape could be made to which HEK293 cells (from human embryonic kidney) and Hep G2 (from human hepatoma) cells non-specifically adhered, while no adhesion of these cells to the non-treated area on the brush was observed. The present results clearly indicate the usefulness of ion beam-printed patterns of anti-biofouling zwitterionic polymer brushes in the biomedical field.     

A clinical trial for therapeutic drug monitoring using microchip-based fluorescence polarization immunoassay

Microchip analysis is a promising method for therapeutic drug monitoring. This led us to evaluate a microchip-based fluorescence polarization immunoassay (FPIA) system for point-of-care testing on patients being treated with theophylline. The sera were collected from 20 patients being treated with theophylline. Fluorescence polarization was measured on the microchip and theophylline concentrations in serum were obtained. Regression analysis of the correlations was done between the results given by the microchip-based FPIA and the conventional cloned enzyme donor immunoassay (CEDIA), and between the results given by the microchip-based FPIA and the conventional particle-enhanced turbidimetric inhibition immunoassay (PETINIA). We successfully carried out a quantitative analysis of theophylline in serum at values near its therapeutic range in 65 s. The results obtained by the microchip-based FPIA correlated well with CEDIA and PETINIA results; the correlation coefficients (R ²) were 0.986 and 0.989, respectively. The FPIA system is a simple and rapid method for point-of-care testing of drugs in serum, and its accuracy is the same as the conventional CEDIA and PETINIA. It is essential to use real samples from patients and to confirm good correlations with conventional methods for a study on the realization of microchip.     

Effect of co-adsorbed CO and reaction temperature on the dynamics of N2 desorption under steady-state N2O-CO reaction on Rh(110)

We have investigated the effect of co-absorbed CO and reaction temperature on the angular distribution of N(2) desorption by N(2)O decomposition under the steady state of N(2)O-CO reaction on Rh(110). Spatial distributions of desorbing product N(2) emission have been measured at various surface temperatures and CO coverages. The decomposed N(2) collimates at 48°-61° off normal in the parallel plane to [001] and [110] directions, indicating that adsorbed N(2)O just before the decomposition is oriented along the [001] direction. Although the inclined and collimated N(2) desorption is always observed at any steady-state CO coverage and reaction temperature, the shape of the collimated N(2) distribution varied dependent on the co-adsorbed CO coverage. The distribution becomes sharp and shifts toward the surface normal direction with increasing CO coverage. These effects of adsorbed CO on the angular distribution of N(2) are interpreted by the collision of desorbed N(2) with co-adsorbed CO.