Enhancement of Light Absorption Ability of Synthetic Chlorophyll Derivatives by Conjugation with a Difluoroboron Diketonate Group

The enhancement of the light absorption ability of synthetic chlorophyll derivatives is demonstrated. Chlorophyll derivatives directly conjugated with a difluoroboron 1,3‐diketonate group at the C3 position were synthesized from methyl pyropheophorbide‐d through Barbier acylmethylation of the C3‐formyl moiety, oxidation of the C3‐carbinol, and difluoroboron complexation of the diketonate. Electronic absorption spectra in a diluted solution showed that the synthetic conjugates gave an absorption band at λ=400–500 nm, with a Qy band shifted to a longer wavelength of λ≈700 nm. DFT calculations demonstrated that the absorption bands and redshifts were ascribable to the coupling of the LUMO of chlorin with that of the difluoroboron diketonate moiety. The introduction of a pyrenyl group at the C3³‐position of the conjugate afforded an additional charge‐transfer band over λ=500 nm, producing a pigment that bridged the green gap in standard chlorophylls.     

Thiol-terminated hydroxy-functional polymer as a transtab toward polymer latex particles

Hydroxy-functional macrodisulfides have been synthesized by atom transfer radical polymerization of 2-hydroxyethyl methacrylate or 2-hydroxypropyl methacrylate in 2-propanol. Mean degrees of polymerization of the polymer chains beside the disulfide were fixed at 30, 60, and 90; since ATRP has reasonably good living character, the molecular weight distribution is relatively narrow. Furthermore, the macrodisulfides were reduced to synthesize corresponding thiol-terminated polymers with relatively narrow molecular weight distributions. ¹H nuclear magnetic resonance and gel permeation chromatography were used to characterize the macrodisulfides and thiol-terminated polymers in terms of their chemical structure, molecular weight, and polydispersity, respectively. Dispersion polymerizations of styrene using the thiol-terminated hydroxy-functional polymers as a transtab (chain transfer agent + colloidal stabilizer) in ethanol resulted in colloidally stable submicrometer-sized polystyrene latex particles. Scanning electron microscopy, Fourier transform infrared spectroscopy, and elemental microanalysis were used to characterize the particles in terms of their morphologies, particle sizes and their distributions, and chemical compositions.     

Stereoscopic story visualization in literary works demonstrated by Shakespeare’s plays

Abstract  

A stereoscopic method of identifying story patterns in literary works is newly developed. The pattern is extracted from textual information by the detection of thematically assigned keywords, and depicted as visual imageries. The applicability of the method is demonstrated in several of Shakespeare’s plays. The complex scenario patterns in Shakespeare’s tragedies are successfully captured with applying the method for two different themes in each play. As the result, the organization of story accompanying multiple themes in a single play has been obtained as a pair of visual imageries, i.e. stereoscopic story visualization. This approach, in combination with a quadrant analysis of the plots, allows us in interpretation further complexity of human psychology in the characters and scene-by-scene transitions in each play.     

Synthesis and Cytotoxic Activity of Oxidized Galactomannan/ADR Conjugate

Abstract

Many polysaccharides are expected to apply as biomaterials because they generally show good biocompatibilities and biodegradabilities. It has recently been reported that the saccharides play important roles in biological recognition and the transmission of biological information on a cellar surface. Galactomannan (GalM) is a polysaccharide whose main chain is composed of β-1,4-linked mannose units only. It has some branching α-galactose residues at the C-6 position of mannose units. Therefore, it was of interest of us to use GalM as a drug carrier which was targeted to hepatocyte having a galactose receptor on its cellar surface. Dicarboxy-galactomannan (DC-GalM), which has reactive functional groups and is a carboxylic acid derivative of galactomannan, was prepared by IO^4-/CIO^2- oxidation of GalM. The obtained DC-GalM showed specific binding with maclura pomifera (MPA) [1] which has a specificity to α-galactose. Moreover, DC-GalM showed selective incorporation into hepatocyte. Adriamycine (ADR), which is one of the most prominent anticancer agents, was immobilized to DC-GalM. The DC-GalM/ADR conjugate showed specific cytotoxic activity against HepG2 human hepatoma cells which have a galactose receptor on the cell surface, compared with Hela utrocervical carcinoma cells which have no galactose receptor.     

Sequence Dependence of Fluorescent Quenching of Chromophores Covalently Bonded to Oligo-DNAs before and after Duplex Formation

The labeling of oligo- and polynucleotides with fluorescent probes is an important technique for the analysis of DNAs and RNAs. The effect of duplex formation with complementary oligo-DNA on the quenching behavior of two fluorescent chromophores (eosin, Eo and tetramethylrhodamine, TMR) attached to the 5′-terminal of various 10mer oligo-DNAs was investigated and the dependence of the quenching on DNA base sequence is discussed. We found that guanine residues played a major role in the quenching of the fluorescence of the chromophores. Guanine residues on the complementary DNA near the chromophores, in particular, had a significant influence on the quenching.     

Discovery of Oxysterol-Derived Pharmacological Chaperones for NPC1: Implication for the Existence of Second Sterol-Binding Site

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Highlights? Niemann-Pick disease type C is caused by folding defect in NPC1 protein ? Oxysterols and chemically optimized derivatives act as pharmacological chaperones ? Defects in localization, stability, maturation, and function were corrected in cell ? These derivatives bind to second sterol-binding site on NPC1 protein     

Spectroscopic Analysis of Two Distinct Equilibrium States for the Exchange Reaction of Sodium Cholate and Oligo‐DNA on Single‐Walled Carbon Nanotubes

Understanding the quantitative analysis of the transition adsorption structures of molecules on single‐walled carbon nanotubes (SWNTs) is of importance from the point of view of both fundamental science and applications of nanotubes. Absorption spectroscopy reveals that two different equilibrium states are existent for the exchange reaction of sodium cholate (SC) and oligo‐DNA (single‐stranded 20‐mer cytosine) on SWNTs. This is derived from the transitions of the adsorption structures of different chirality‐types of SWNTs and SC/DNA at certain SC concentrations below the critical micelle concentration of SC.     

Ionization of pesticides using a far-ultraviolet femtosecond laser in gas chromatography/time-of-flight mass spectrometry

The fourth harmonic emission (200 nm) of a femtosecond Ti:sapphire laser (35 fs) was generated and used in the multiphoton ionization of 49 pesticides in gas chromatography/time-of-flight mass spectrometry. The limit of detection was improved when the ionization source from the third harmonic emission (267 nm) was replaced with the fourth harmonic emission for several pesticide molecules that contained no conjugated double bonds since their absorption bands are located in the far-ultraviolet region. This analytical instrument was used in the analysis of a series of real samples including potatoes, carrots, and cabbage, and a signal suspected to arise from di-allate was observed for the potato sample.