Fullerene/cobalt porphyrin hybrid nanosheets with ambipolar charge transporting characteristics

A novel supramolecular nanoarchitecture, comprising C(60)/Co porphyrin nanosheets, was prepared by a simple liquid-liquid interfacial precipitation method and fully characterized by means of optical microscopy, AFM, STEM, TEM, and XRD. It is established that the highly crystalline C(60)/Co porphyrin nanosheets have a simple (1:1) stoichiometry, and when incorporated in bottom-gate, bottom-contact field-effect transistors (FETs), they show ambipolar charge transport characteristics.     

Sabiperones A-F, new diterpenoids from Juniperus sabina

Six new diterpenoids, sabiperones A-F (1-6) have been isolated from the aerial part of Juniperus sabina. Their structures were elucidated by spectroscopic methods including 2D NMR techniques. Sabiperone F showed moderate cell growth inhibitory activities against five human cancer cell lines.     

Preliminary Studies for Cephamycin C Purification Technique

A study was made for purification of cephamycin C from fermentation of Streptomyces clavuligerus. Initially, the culture broth was clarified by microfiltration and ultrafiltration, after which the resulting permeates were subjected to nonspecific adsorption and ion-exchange chromatography on resin columns. The antibiotic activity was measured by the biological method at each stage by assaying its activity against the Escherichia coli ESS, super sensitive to β-lactam antibiotic. The purification processes were assessed in relation to the variables affecting each step. The purification efficiency by nonspecific adsorption was monitored by UV spectrophotometry, while the ion-exchange adsorption fractions were assessed by NMR spectroscopy. Some of the fractions obtained during purification were also analyzed by mass spectrometry (LC/MS and LC/MS/MS) to identify the cephamycin C molecule. These preliminary results proved the process feasibility.     

Solid phase extraction using a sulfoxide adsorbent for preconcentration and separation of Hg(II) in natural water followed by ICP-MS measurements

A separation and preconcentration method based on solid-phase extraction using sulfoxide adsorbent was developed for the determination of Hg(II) in natural water samples by inductively coupled plasma mass spectrometry (ICP-MS). The sulfoxide adsorbent was packed into a commercially available syringe-driven column (with a bed volume of 1.0 mL), which permitted off-line sample loading and on-line elution/measurement. The optimized operating conditions were as follows: sample condition for Hg(II) adsorption, 0.5% HCl; sample-loading flow rate, 10 mL min(-1); eluent for recovering Hg(II), 1% cysteine water solution. A test using multi-element mixed solution showed that most trace elements in natural water, except for Bi, could be completely separated from Hg(II). The recoveries of Hg(II) were 99.0 ± 3.2 and 100.7 ± 4.3%, respectively, when 0.64 and 0.16 ng mL(-1) of Hg(II) were added into the test sample. The detection limit of Hg(II) using a quadrupole ICP-MS after 10-fold preconcentration was 1.5 pg mL(-1). The blank value was 2.8 ± 0.5 pg mL(-1).     

Multiplexed assay for proteins based on sequestration electrochemistry using the protein binding electroactive magnetic microbeads

The paramagnetic microbead-based electrochemical binding assay was demonstrated for detecting two kinds of protein simultaneously. The principle of this assay is based on the sequestration electrochemistry. The protein binding electroactive magnetic microbeads which are conjugated with an electroactive compound and a ligand to bind specifically with a target protein were prepared. The avidin-biotin and soybean agglutinin (SBA)-galactosamine were chosen as model protein-ligand systems. The avidin binding electroactive magnetic microbead (ABEMMb) and SBA binding electroactive magnetic microbead (SBEMMb) are constructed by biotin/thionine and galactosamine/ferrocene modified on paramagnetic microbeads. The voltammetric response for these functionalized microbeads was measured by the Nd-Fe-B magnet-incorporating carbon paste rotating disk electrode. The measurements were performed in a microliter droplet using a rotating disk electrode system. Avidin and SBA were simultaneously detected by the decrease in the current responses from the reduction of ABEMMb and SBEMMb that was caused by the binding with target proteins. The limits of detection for avidin and SBA were 4 × 10(-10) and 2 × 10(-10) M, respectively.     

Novel megastigmanes with lipid accumulation inhibitory and lipid metabolism-promoting activities in HepG2 cells from Sedum sarmentosum

Four novel megastigmanes, neosedumosides I (1), II (2), III (3), and IV (4) were isolated from the whole plant of Sedum sarmentosum (Crassulaceae). Absolute stereostructures of these constituents were determined on the basis of chemical and physicochemical evidence. Among them, 1-3 were found to show lipid accumulation inhibitory activity in HepG2 cells. Furthermore, 2 and 3 were found to also show lipid metabolism-promoting activity.     

Langmur monolayers of cerebroside with different head groups originated from sea cucumber: Binary systems with dipalmitoylphosphatidylcholine (DPPC)

Surface properties (Langmuir monolayer) of two different cerebrosides which are extracted from the sea cucumber (Bohadschia argus) were investigated. A main difference in chemical structure of cerebroside between BAC-2a and BAC-4 is their head groups (glucose and galactose, respectively). Furthermore, miscibility and interaction between dipalmitoylphosphatidylcholine (DPPC) and cerebrosides (BAC-2a and BAC-4) in the monolayer have been systematically examined. The surface pressure (π)−area (A), the surface potential (ΔV)−A, and the dipole moment (μ)−A isotherms for monolayers of DPPC, cerebrosides, and their binary combinations have been measured using the Wilhelmy method and the ionizing electrode method. BAC-4 forms a stable liquid-expanded (LE) monolayer, whereas BAC-2a has a first-order phase transition from the LE phase to the liquid-condensed (LC) state on 0.15 M NaCl at 298.2 K. The fundamental properties for each cerebroside monolayer were elucidated in terms of the surface dipole moment based on the three-layer model [R.J. Demchak, T. Fort Jr., J. Colloid Interface Sci. 46 (1974) 191–202] for both cerebrosides and the apparent molar quantity change (Δs^γ, Δh^γ, and Δu^γ) for BAC-2a. In addition, their miscibility with DPPC was examined by the variation of the molecular areas and the surface potentials as a function of cerebroside mole fractions, the additivity rule. The miscibility was also confirmed by constructing the two-dimensional phase diagrams. The phase diagrams for the both binary systems were of negative azeotropic type. That is, the two-component DPPC/BAC-2a and DPPC/BAC-4 monolayers are miscible. Furthermore, the Joos equation for the analysis of the collapse pressure of binary monolayers allowed calculation of the interaction parameter and the interaction energy between the DPPC and cerebroside monolayers. The miscibility in the monolayer state was also confirmed by the morphological observation with Brewster angle microscopy (BAM), fluorescence microscopy (FM), and atomic force microscopy (AFM).     

Direct profiling of phytochemicals in tulip tissues and in vivo monitoring of the change of carbohydrate content in tulip bulbs by probe electrospray ionization mass spectrometry

Probe electrospray ionization (PESI) is a recently developed ESI-based ionization technique which generates electrospray from the tip of a solid needle. In this study, we have applied PESI interfaced with a time of flight mass spectrometer (TOF-MS) for direct profiling of phytochemicals in a section of a tulip bulb in different regions, including basal plate, outer and inner rims of scale, flower bud and foliage leaves. Different parts of tulip petals and leaves have also been investigated. Carbohydrates, amino acids and other phytochemicals were detected. A series of in vivo PESI-MS experiments were carried out on the second outermost scales of four living tulip bulbs to monitoring the change of carbohydrate content during the first week of initial growth. The breakdown of carbohydrates was observed which was in accordance with previous reports achieved by other techniques. This study has indicated that PESI-MS can be used for rapid and direct analysis of phytochemicals in living biological systems with advantages of low sample consumption and little sample preparation. Therefore, PESI-MS can be a new choice for direct analysis/profiling of bioactive compounds or monitoring metabolic changes in living biological systems.     

Characteristic alkaline catalyzed degradation of kotalanol, a potent α-glucosidase inhibitor isolated from Ayurvedic traditional medicine Salacia reticulata, leading to anhydroheptitols: another structural proof

Stereochemical structure of kotalanol (2), a highly potent α-glucosidase inhibitor isolated from an Ayurvedic traditional medicine Salacia reticulata, was proved by alkaline catalyzed degradation of natural kotalanol (2), in which characteristic stereospecific cyclization of the degradative side chain leading to anhydroheptitols (10 and 11) was involved.     

Creation of unique supramolecular nanoarchitectures utilizing natural polysaccharide as a one-dimensional host

We recently revealed that β-1,3-glucans act as unique natural nanotubes, which can accept functional polymers and molecular assemblies in an induced-fit manner. A variety of individual conjugated polymers or molecular assemblies can be incorporated into the one-dimensional hollow constructed by the helical superstructure of β-1,3-glucans to create water-soluble one-dimensional nanocomposites. The advantageous point of the present hosting system is that the selective modification of β-1,3-glucans leads to the creation of various functional one-dimensional nanocomposites in a supramolecular manner. Furthermore, the composites with functional surfaces can act as one-dimensional building blocks toward further hierarchical self-assembles, leading to the creation of two- or three-dimensional nanoarchitectures, which are applicable for fundamental nanomaterials.