Anti-Acanthamoeba effect of potassium isostearate for use as a multipurpose solution.

Acanthamoeba is one of the organisms that cause corneal infection. In this study, attention was focused on potassium isostearate (iso-C18K, a branched chain fatty acid salt) for use in a multipurpose solution (MPS) against Acanthamoeba. An anti-amoebic test against Acanthamoeba castellanii ATCC 30010 (trophozoites type) was conducted. As a result, a growth reduction effect of 4 log units (99.99% suppression) was observed after incubation with 150 mM (5.0 w/v%) iso-C18K for 10 minutes. Furthermore, after the amoeba suspension was mixed with iso-C18K, disruption of cell membranes were observed, and the minimum amoebacidal concentration (MAC) at that time was 9.6 mM (0.31 w/v%). To evaluate the effectiveness as an MPS, assessment by verification tests was conducted using contact lenses. Reducing the concentration of iso-C18K caused a decrease in the number of viable cells, which was confirmed at a MAC of 1.2 mM (0.039 w/v%).

Linear symmetric liquid crystal trimers exhibiting supramolecular chiral architectures.

We prepared a homologous series of achiral liquid crystal trimers (I-n) in which two phenylpyrimidine units and one biphenyl unit were connected via flexible spacers, and investigated the physical properties. All the trimers possessing odd-numbered methylene spacers exhibited soft crystalline chiral conglomerate phases. X-ray diffraction measurements reveal that they have an intercalated layer structure. On the other hand, the trimers possessing even-numbered spacers showed nematic and smectic C phases. We investigated the surface structures of odd-membered trimers in the soft crystalline phases using scanning electron microscopy. Trimers I-3 and I-5 were found to form cylindrical tubes, whereas trimers I-7, I-9 and I-11 toroidal pits. We discuss the formation of diverse supramolecular architectures in terms of the anisotropy of the chirality transfer.

Optimization of single strand DNA incorporation reaction by Moloney murine leukaemia virus reverse transcriptase.

In this study, we investigated CIS reaction (clamping-mediated incorporation of single-stranded DNA with concomitant DNA syntheses) of Moloney murine leukaemia virus reverse transcriptase (MMLV-RT), and established a set of conditions with which single-stranded DNA is ligated to a G-tailed model substrate DNA at efficiencies close to 100%. Prior to the CIS reaction, a target blunt-end DNA was 3' G-tailed by MMLV-RT in the presence of a tailing enhancer, deoxycytidine. In the CIS reaction, the G-tail reacted with a single-stranded DNA carrying a stretch of Cs on its 3' end (termed as GAO for guide adaptor oligonucleotide), and MMLV-RT performed DNA polymerization, starting from the 3' overhang, using the GAO as a template. We could append a given nucleotide sequence of as long as 72 nucleotides, which would be sufficient for various NGS-sequencing platforms. The high efficiency and the unique features of this MMLV-RT activity that enables the labelling of each DNA molecule with a unique degenerate sequence as a molecular identifier has many potential uses in biotechnology.

Versatile Amine-Promoted Mild Methanolysis of 3,5-Dinitrobenzoates and Its Application to the Synthesis of Colorado Potato Beetle Pheromone.

A mild deacylation method for 3,5-dinitrobenzoates using methanolic solutions of amines, such as dialkylamines, was developed. The method's versatility was confirmed by applying it to synthesizing a key intermediate for Colorado potato beetle pheromone.

Achiral flexible liquid crystal trimers exhibiting gyroid-like surfaces in chiral conglomerate phases.

Chiral conglomerate phases have attracted much attention not only for the spontaneous mirror symmetry breaking but also for their nanostructures. We investigated both surface and bulk structures of a homologues series of an achiral liquid crystal trimer I-(n,m) exhibiting soft crystalline chiral conglomerate phases by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The trimers were found to form bicontinuous networks. In particular, trimer I-(9,9) exhibited a single gyroid-like surface accompanying periodic distribution of dimples with a size of about 100 nm. It showed a sponge-like structure in the bulk of the material. The twist conformation of the flexible trimer I-(n,m) can cause layer deformation, which produces bicontinuous networks exhibiting optical activity.

Optically Isotropic Homochiral Structure Produced by Intercalation of Achiral Liquid Crystal Trimers.

Dark conglomerates of domains with opposite handedness, which are designated dark conglomerate phases (DC phases), have attracted much attention. We prepared an achiral liquid crystal trimer, 4,4'-bis{9-[4-(5-octyloxypyrimidin-2-yl)phenyloxy]nonyloxy}biphenyl (I-9), and investigated the physical properties. A droplet of trimer I-9 formed a conventional nematic phase on cooling from the isotropic liquid, and then changed to an optical isotropic phase with homochirality. X-ray diffraction measurements reveal that the isotropic phase has an intercalated layer structure with a correlation length of 95 nm. We prepared binary mixtures with a nematic liquid crystal, 4'-hexyloxy-4-cyanobiphenyl (6OCB). The mixtures containing 30-75 mol % of 6OCB exhibited smectic phases above the isotropic phase. We investigated mesogenic properties of trimer I-n (n = 5-9) depending on the parity of the linking group. Only trimer I-9 possessing the longest odd-numbered spacers showed the chiral isotropic phase, suggesting that a rigid bent structure is not necessary for the appearance of the isotropic phase. The experimental results reveal that trimer I-9 exhibits a soft crystalline DC phase representing a new modification of chiral symmetry breaking in lamellar liquid crystal phases.

Achiral flexible liquid crystal trimers exhibiting chiral conglomerates.

Chiral conglomerates of domains with opposite handedness have attracted much attention from researchers. We prepared a homologous series of achiral liquid crystal trimers in which two phenylpyrimidine units and one biphenyl unit were connected via flexible methylene spacers. We investigated their phase transition behaviour. Some trimers possessing odd-numbered spacers were found to exhibit a nematic phase and a dark chiral conglomerate phase possessing a layered structure. The chiral characteristics were confirmed by uncrossing the polarizers in opposite directions. The layer spacing detected using X-ray diffraction was about 80% of the molecular length. The structure-property relations indicate that intermolecular interactions cause a conformational change in the trimers possessing flexible odd-numbered methylene spacers to form helical conformers with axial chirality, which might induce chiral segregation and layer deformation to drive the chiral conglomerates.

Chiral conglomerates observed for a binary mixture of a nematic liquid crystal trimer and 6OCB.

Dark conglomerates of domains with opposite handedness, which are designated as dark conglomerate phases (DC phases), have attracted much attention. After designing an achiral liquid crystal trimer, 4,4'-bis{7-[4-(5-octyloxypyrimidin-2-yl)phenyloxy]heptyloxy}biphenyl (1), which exhibits only a nematic phase, we prepared binary mixtures with some typical rod-like nematic liquid crystals, i.e., 4'-hexyloxy-4-cyanobiphenyl (6OCB), 2-(4-hexyloxyphenyl)-5-pentyloxypyrimidine (PPY), or 4-methyloxyphenyl 4-hexyloxycyclohexanecarboxylate (PCA), and investigated their phase transition behaviour. The binary mixtures containing 55­90 mol% of 6OCB were found to exhibit a nematic phase and a DC phase of chiral domains with opposite handedness. However, neither PPY nor PCA induced such a chiral conglomerate phase in the mixture with trimer 1. We discuss how core­core interactions contribute to produce such a chiral conglomerate phase.

Supermolecular bent configuration composed of achiral flexible liquid crystal trimers exhibiting chiral domains with opposite handedness.

Chirality's effects on physical properties of materials and how chirality arises have persisted as attractive issues in chemistry. We prepared a homologous series of achiral liquid crystal trimers in which three phenylpyrimidine units are connected via flexible heptamethylene spacers. An equimolecular mixture of a trimer with a nematic (N) phase and that with smectic A (SmA), smectic C (SmC), and smectic B phases was found to exhibit an N phase, a SmC phase, and a B4 phase composed of chiral domains with opposite handedness. The chiral characteristics of the B4 phase were confirmed by uncrossing the polarizers in opposite directions. XRD measurements reveal that both SmC and B4 phases have an interdigitated layer structure. That molecular interdigitation might form a supermolecular bent configuration that can produce saddle splay curvature to drive the B4 phase.