Chirality is widely expressed in organic materials, perhaps most notably in biological molecules such as DNA, and in proteins, owing to the homochirality of their components (d-sugars and l-amino acids). But the occurrence of large-scale chiral pores in inorganic materials is rare1. Although some progress has been made in strategies to synthesize helical and chiral zeolite-like materials1,2,3, the synthesis of enantiomerically pure mesoporous materials is a challenge that remains unsolved4. Here we report the surfactant-templated synthesis of ordered chiral mesoporous silica, together with a general approach for the structural analysis of chiral mesoporous crystals by electron microscopy. The material that we have synthesized has a twisted hexagonal rod-like morphology, with diameter 130–180 nm and length 1–6 µm. Transmission electron microscopy combined with computer simulations confirm the presence of hexagonally ordered chiral channels of 2.2 nm diameter winding around the central axis of the rods. Our findings could lead to new uses for mesoporous silica and other chiral pore materials in, for example, catalysis and separation media, where both shape selectivity and enantioselectivity5 can be applied to the manufacturing of enantiomerically pure chemicals and pharmaceuticals.

Synthesis and characterization of chiral mesoporous silica

A novel anionic gemini-type surfactant with no spacer group, disodium 2,3-didodecyl-1,2,3,4-butanetetracarboxylate (GS), was investigated for its phase behavior in water, water/decane, and water/cosurfactant systems in a wide range of compositions. At low surfactant concentration in the GS−water binary system, a micellar solution phase is formed which transforms to a hexagonal (H1) phase, as in conventional ionic surfactant systems. At high GS concentration, however, the H1 phase transforms to the rectangular-ribbon (R1) liquid−crystal phase. Since the GS molecule has no spacer group, a small cross-sectional area of the headgroup and closely packed hydrophobic chain tend to increase the packing constraints of the lipophilic core with increasing surfactant concentration, thereby inducing the H1−R1 phase transition. In the presence of a normal hydrocarbon like decane, the H1 phase is changed to a micellar cubic phase. On the other hand, the surfactant layer curvature becomes less positive upon addition of a...

Phase and Rheological Behavior of Novel Gemini-Type Surfactant Systems

Self-assembly in Solution and adsorption at the air-water interface and at Solid Surfaces were investigated for two amino-acid-based surfactants with conductimetry, NMR, tensiometry, quartz crystal microbalance with monitoring or the dissipation (QCM-D), and surface plasmon resonance (SPR). The surfactants studied were sodium N-lauroylglycinate and sodium N-lauroylsarcosinate, differing only in a methyl group on the amide nitrogen for the sarcosinate. Thus, the glycinate but not the surfactant is capable of forming intermolecular hydrogen bonds via the amide group. It was found that the amide bond, N-methylated or not, gave a substantial contribution to the hydrophilicity of the amphiphile. The ability to form intermolecular hydrogen bonds led to tighter packing at the air-water interface and ill a hydrophobic surface. It also increased the tendency for precipitation as all acid-soap pair oil addition of acid. Adsorption of the surfactants at a gold surface Was also investigated and gave unexpected results. The sarcosine-based surfactant seemed to give bilayer adsorption, while the glycine derivative adsorbed as a monolayer.

Role of an amide bond for self-assembly of surfactants.

Although dynamic stress changes associated with the passage of seismic waves are thought to trigger earthquakes at great distances, more than 60 per cent of all aftershocks appear to be triggered by static stress changes within two rupture lengths of a mainshock. The observed distribution of aftershocks may thus be used to infer details of mainshock rupture geometry. Aftershocks following large mid-continental earthquakes, where background stressing rates are low, are known to persist for centuries, and models based on rate-and-state friction laws provide theoretical support for this inference. Most past studies of the New Madrid earthquake sequence have indeed assumed ongoing microseismicity to be a continuing aftershock sequence. Here we use instrumentally recorded aftershock locations and models of elastic stress change to develop a kinematically consistent rupture scenario for three of the four largest earthquakes of the 1811-1812 New Madrid sequence. Our results suggest that these three events occurred on two contiguous faults, producing lobes of increased stress near fault intersections and end points, in areas where present-day microearthquakes have been hitherto interpreted as evidence of primary mainshock rupture. We infer that the remaining New Madrid mainshock may have occurred more than 200 km north of this region in the Wabash Valley of southern Indiana and Illinois--an area that contains abundant modern microseismicity, and where substantial liquefaction was documented by historic accounts. Our results suggest that future large mid-plate earthquake sequences may extend over a much broader region than previously suspected.

Analysing the 1811–1812 New Madrid earthquakes with recent instrumentally recorded aftershocks

L-Citrulline is a naturally occurring non-essential amino acid, an intermediate in urea cycle and conditionally essential in intestinal pathology. It is a potent hydroxyl radical scavenger and much more effective precursor of arginine and nitric oxide (NO) than arginine itself so exploited in therapeutics. Plasma citrulline concentration is used by clinicians to assess functional enterocyte mass in various chronic and acute small bowel pathologies like short bowel syndrome that has become an indication in clinical practice. Its supplementation is likely to be used in conditions like erectile dysfunction, sickle cell anemia, short bowel syndrome (to restore nitrogen balance), hyperlipidemia, cancer chemotherapy, hypercholestremia, in hyperoxic lung damage, urea cycle disorders, Alzheimers disease, multi-infarct dementia and as an immunomodulator. Its emerging role as a biomarker in intestinal pathology and early diagnosis of Rheumatoid arthritis has spread considerable interest. Antibody detection to Anti-cyclic citrullinated peptide (ACCP) antibodies can be recommended for early detection of RA decreasing joint damage and deformity, because these are detected well before the onset of disease manifestations of RA. The test is highly specific than RF (Rheumatoid factor), with moderate sensitivity, but much useful in differentiating RA from other disorders. Further studies and exploration is required in these areas.

Citrulline: pharmacological perspectives and its role as an emerging biomarker in future.

The phase behavior in the brine/sodium N-dodecanoyl sarcosinate (Sar)/isopropyl N-dodecanoyl sarcosinate (SLIP) system has been investigated by means of phase study, static light scattering, and small-angle X-ray scattering. The liquid crystal phases, hexagonal (H(1)) and discontinuous cubic (I(1)), melt upon the addition of NaCl, which shows the similar effect to the increasing of temperature. The addition of SLIP to the brine/Sar solution at high Sar concentration induces the phase transition from H(1) to I(1) via the isotropic micellar solution (W(m2)). The micellar structure in the W(m2) phase also changes from the wormlike to the globular micelle with SLIP concentration. Adding NaCl reduces the repulsive force between the Sar head groups and simultaneously the space of the solubilized SLIP in the palisade layer, leading SLIP to shift their location further into the micelle core. As a consequence, the hexagonal symmetry breaks into the micelle solution and the liquid crystal order is destabilized entropically.

Formation of intermediate micellar phase between hexagonal and discontinuous cubic liquid crystals in brine/N-acylamino acid surfactant/N-acylamino acid oil system

The phase behavior of potassium N-dodecanoyl-DL-alaninate (DL-KDA) and potassium N-dodecanoyl-L-alaninate (L-KDA) in water and water/decanol systems have been investigated. In the DL-KDA/water binary system, normal micellar solution (Wm), hexagonal (H1), bicontinuous cubic (V1) phase with Ia3d symmetry, and hydrated solid (S) phases are formed successively with increase in surfactant concentration at 25 °C. The phase behavior of L-KDA is essentially similar to that of the DL-KDA system except that the melting temperature of solid phase is high. In the DL-KDA/water/1-decanol system, lamellar (Lα), reverse hexagonal (H2) and reverse micellar (Om) phases are formed successively at 25 °C with increase in 1-decanol concentrations. Addition of decanol to the H1 phase induced a H1-Lα transformation via intermediate phases. At lower surfactant concentrations, nematic (N) and discotic lamellar (LαD) phases are found, whereas at higher surfactant concentrations rectangular ribbon (R1) and defected lamellar (LαH) phases are observed. The L-KDA/water/1-decanol system shows that a chiral nematic or cholesteric (Ch) phase is present (instead of the N phase observed in the DL-KDA system) at low decanol concentrations. However, a similar phase behavior is observed at high decanol concentrations for both surfactant systems. Hence, the optical activity of the surfactant has a significant effect on the phase behavior only in the presence of a low amount of decanol. This phenomenon has been explained by the change in the effective cross-sectional area at the aggregate interfaces.

Phase Behavior and Effect of Enantiomerism on Potassium N -Dodecanoyl Alaninate/Water/Decanol Systems

The interaction and the function of some amino acids in hair care applications are discussed. When amino acids are applied to hair in the form of simple aqueous solution, uptake of the amino acids is mainly controlled by ionic equilibrium. When amino acids were incorporated in a hair conditioner, the result was quite different, suggesting the importance of interaction between the amino acids and the cationic surfactants. Uptake of pyrrolidone carboxylic acid (PCA), a derivative of glutamic acid, is enhanced by combining with arginine, an amino with strong affinity towards hair. Effects of some amino acids on bleached/dyed hair are described. A hair conditioner incorporated with alanine improves hair surface hydrophobicity of bleach-damaged hair. Histidine and phenylalanine improve tensile strength. PCA was proved to be effective to improve color-retention of dyed hair.

Hair and amino acids: the interactions and the effects.

The purpose of this study was to measure the protective effects of arginine in oxidative coloring or bleaching process. Contact angle measurement, tensile measurement and amino acid analysis were employed. As the first step, it was shown that oxidative coloring or bleaching process decreases hair surface hydrophobicity and tensile strength in wet condition. Next the study has been conducted with coloring agents in which part of the ammonia was replaced with arginine, to find that arginine reduced the oxidative change in contact angle and tensile strength. These results suggest that arginine prevents the undesirable attack by hydrogen peroxide on hair proteins and hair surface lipids. Furthermore, it is also suggested from amino acid analysis that a considerable amount of arginine is deposited on, or in hair fibers from coloring agents.

Effects of arginine on hair damage via oxidative coloring process.

Aqueous preservative solutions with a high amino acid content which is excellent in preservation, particularly a preservative effect on fungi, and safety, and is excellent in storage stability so as not to cause a problem such as depositing, coloring or smelling even when it is stored for a long time, and when incorporated in a cosmetic, is capable of imparting a high moisturizing effect without causing a sticky feeling, and imparting an effect of preventing dyed hair from color fading, can be achieved by incorporating pyrrolidone carboxylic acid and/or a salt thereof (Component A), a basic amino acid and/or a salt thereof (Component B), an acidic amino acid and/or a salt thereof (Component C), a neutral amino acid and/or a salt thereof (Component D) and lactic acid and/or a salt thereof (Component E) at a specific incorporation ratio and at a specific pH.

Eiko Oshimura

Papers

Formation of intermediate micellar phase between hexagonal and discontinuous cubic liquid crystals in brine/N-acylamino acid surfactant/N-acylamino acid oil system

Phase Behavior and Effect of Enantiomerism on Potassium N -Dodecanoyl Alaninate/Water/Decanol Systems

Hair and amino acids: the interactions and the effects.

Effects of arginine on hair damage via oxidative coloring process.

Aqueous preservative solution with high amino acid content