Amphiphilic Organic Molecules Research Articles

Generation of long-chain fatty acids by hydrogen-driven bicarbonate reduction in ancient alkaline hydrothermal vents

The origin of life required membrane-bound compartments to allow the separation and concentration of internal biochemistry from the external environment and establish energy-harnessing ion gradients. Long-chain amphiphilic molecules, such as fatty acids, appear strong candidates to have formed the first cell membranes although how they were first generated remains unclear. Here we show that the reaction of dissolved hydrogen and bicarbonate with the iron-rich mineral magnetite under conditions of continuous flow, alkaline pH and relatively low temperatures (90 °C) generate a range of functionalised long-chain aliphatic compounds, including mixed fatty acids up to 18 carbon atoms in length. Readily generated membrane-forming amphiphilic organic molecules in the first cellular life may have been driven by similar chemistry generated from the mixing of bicarbonate-rich water (equilibrated with a carbon dioxide-enriched atmosphere) with alkaline hydrogen-rich fluids fed by the serpentinisation of the Earth’s iron-rich early crust.

Smart synthesis of highly porous metal oxide powders with the self-assembly of amphiphilic organic compounds.

Supramolecular chemistry-mediated synthesis has thus far been employed for the design of ordered mesoporous structures surrounded by various metal oxides that are helpful as nanometer-scaled unique reaction containers with high specific surface area, large pore volume and uniform mesopores useful for the storage and mass transport of large-sized molecules. The evaporation-induced self-assembly (EISA) process is very powerful for fabricating mesoporous metal oxide films with the rapid evaporation of solvents. Although a similar EISA process is also applied to synthesize mesoporous metal oxide powders using the room-temperature drying process with slow evaporation of solvents, the control of the evaporation rate should be quantified for the complete reproduction of high-quality metal oxide powders. In this feature article, I introduce our recent challenge in synthesizing highly porous metal oxides in powder form with the smart optimization of synthetic conditions by combining several EISA processes to eliminate the mismatch of the rate of solvent evaporation, inducing the self-assembly of amphiphilic organic molecules.

Neutralization-mediated extraction of amphiphilic organic molecules for obtaining high-quality mesoporous alumina.

A solvent extraction method was improved using organic bases such as triethylamine (Et3N) that neutralize HCl effectively and stabilize sol-gel derivative alumina frameworks as insoluble species, thereby achieving removal of EOnPOmEOn at a rate higher than 90% to obtain high-quality mesoporous alumina.

Roles of hydrogen bonding interactions and hydrophobic effects on enhanced water structure in aqueous solutions of amphiphilic organic molecules

Insights into the solute-induced water structural transformations are essential to understand the role of water in biological and chemical reaction processes. Herein, the structural changes in water induced by amphiphilic organic molecules were investigated using concentration-dependent derivative Raman spectroscopy (DRS) combined with two-dimensional Raman correlation spectroscopy (2D Raman-COS). We shall restrict our attention in this work to binary mixtures of water with dimethyl sulfoxide (DMSO), acetone, and isopropanol (IPA), all of which have similar chemical structures. The spectral changes in O:H and OH stretching modes illustrate that the solute molecules induce an enhancement of the water structure in dilute solutions, where the enhanced degree of water structure is closely related to the size of the dipole moment of organic molecules. In addition, the transformations of solute-induced water-specific structures were evaluated by 2D Raman-COS, which shows that the strong hydrogen bond (H-bond) structure of water is more sensitive to organic molecules and induces a transition to the weak H-bond structure of water.

Porous materials fabricated from Pickering foams stabilized by natural plant of Angelica sinensis for removal of Cd (II) and Cu (II)

The emulsion or foam templating applied in the preparation of porous materials have been widely studied. As the enhancement of the green and environmental protection awareness in preparation process, the stabilization of the emulsion or foam with the natural matter has been attracted extensive attention. In this work, a high stable Pickering water-based foams was stabilized by the natural plant Angelica sinensis, and a novel porous material of Polyacrylic acid-Angelica sinensis (PAA-AS) was fabricated from the Pickering foam via a thermally-initiated polymerization. Duo to the amphiphilic organic molecules was rich in AS, such as phenolic acids, saponins, etc., the water-based foam can be stabilized by the AS particles alone. The as-prepared porous materials had sufficient pore structure, and the pore size could be controlled by changing the dosage of AS. PAA-AS was applied to remove heavy metal ions from water, and the adsorption capacities for Cd2+ and Cu2+ could be reached to 372.74 mg/g and 186.83 mg/g, respectively. In brief, this research provided a new approach to prepare environmentally friendly porous materials, and the materials has the applications potential in water treatment.

Understanding of NOx storage property of impregnated Ba species after crystallization of mesoporous alumina powders

The regulation of automobile exhaust gas, especially that concerning hazardous nitrogen oxide (called as NOx) becomes stricter year-by-year, which should be urgently corresponded for cleaning the NOx containing emission. According to surface affinity of γ-alumina to metal catalysts and its thermal stability, crystalline γ-alumina has been frequently utilized as catalyst supports showing relatively high specific surface area. From the viewpoint, we consider that highly porous alumina powders prepared using amphiphilic organic molecules are potential as such a catalyst support for improving NOx removing property. In this study, we report surface property of the mesoporous alumina powders against NOx molecules after crystallizing to its γ-phase and NOx storage property after impregnation of barium (Ba) acetate in the mesopores. Adsorption of NO with O2 on mesoporous γ-alumina powders without Ba species were more likely to be bridging bidentate than chelating bidentate nitrates (NO3−) with comparing to commercially available γ-alumina powders. After impregnating the Ba species, admitted NO molecules were oxidized with enough O2 and stored very strongly as ionic nitrate (NO3−) onto the Ba species even after heating at 500 °C. This preliminary study is helpful for designing mesoporous deNOx catalysts combined with unique storage/adsorption property.

Further Understanding of the Reactivity Control of Bisphosphonates to a Metal Source for Fabricating Highly Ordered Mesoporous Films.

Mesoporous metal organophosphonates having embedded organic functions are a promising platform to hybridize organics and non-siliceous inorganic frameworks in their molecular scale. However, the reactivity between a bisphosphonate and a metal source is dramatically different for their combination and then hampers to construct ordered mesoporous structures even when using amphiphilic organic molecules. By proposing an advanced method to adjust such reactivity, we recently succeeded in fabricating ordered mesoporous aluminum organophosphonate (AOP) films with chemically designable benzene units inside their hybrid frameworks. The reactivity of the organically bridged bisphosphonates has been controlled by utilizing dissimilar reactivities of acid-base pairs like P-OH and P-OEt groups to AlCl3 . Here, we further prove our reactivity-control concept through the introduction of organic groups, such as those having symmetric thiophene, asymmetric amide, and hydrophilic ether units. Liquid-state 31 P NMR measurements further clarified the usefulness of the control of the -OH/ -OEt ratio in the same bisphosphonate molecules for obtaining highly ordered mesostructured AOP films.

Infrared external reflection spectra of Janus gold nanoparticle monolayers prepared at the air–water interface

Abstract. Nanoparticle monolayers at the air–water interface have received broad attention because of their potential applications owing to the tunability of their surface properties. We prepared gold nanoparticle monolayers by adsorption of hydrophilized nanoparticles from solution onto Langmuir monolayers of amphiphilic organic molecules (polyion complexes of deuterated stearic acid and polyallylamine) at the air–water interface, followed by adsorption of dodecyltrimethylammonium bromide onto the underside of these particles. The infrared external reflection spectra of the monolayers recorded both during and after preparation showed that the adsorption of gold nanoparticles on the Langmuir monolayers and that of dodecyltrimethylammonium bromide on the nanoparticles occurred in several tens of minutes. The infrared spectra also showed that both stearic acid and dodecyltrimethylammonium bromide molecules were highly ordered on the gold nanoparticles at the air–water interface. These results suggested that this preparation procedure is a useful fabrication method for Janus particles.

Поверхневий плазмонний резонанс: підходи і перспективи використання для дослідження вірус-специфічних взаємодій

In the review the published data on the use of surface plasmon resonance methods for the study of individual viral proteins as well as intact viruses are reviewed. . The principles of the method, its benefits and peculiarities of its use to study viruses are introduced. Particular attention is paid to the requirements to the sensor surface and the methods of its modification, including the formation self assembled monolayers of amphiphilic organic molecules containing functional groups to connect to the surface, creating of the intermediate protective thiocyanate layer between protein and metal, forming of the favorable microenvironment using dextran hydrogels around biomolecules, immobilization of proteins on the surface of the sensor using streptavidin-biotin system, use of protein A Staphylococcus aureus as an sensitive element of the sensory system structure. The approaches to enhance the signal used in virological studies, including the use of labeled antibodies, using competitive analysis for the detection of small molecules, the formation of a complex directly on the sensor surface, and immobilization on the surface of the sensor previously obtained complex receptor-analyte are considered. The conclusion is that the SPR method contains many potential opportunities to study various aspects of the interaction of viruses with specific agents, and changes in the structure of viruses caused by various external factors.

Evaporation-induced Self-assembly Process Controlled for Obtaining Highly Ordered Mesoporous Materials with Demanded Morphologies.

A large number of periodic mesoporous materials have been reported using amphiphilic organic molecules with increasing development of synthetic methods for mesostructural, morphological, and compositional designs. The evaporation-induced self-assembly (ESIA) process to fabricate ordered mesoporous films is one of the most essential synthetic methods, which has extensively been applied for obtaining a wide variety of samples (e.g., films and monoliths, including powders). It contains complicated physical variations and chemical reactions, but has been simply explained by several research groups. However, a current, exact understanding of such complicated systems should be given with respect to all the variations and reactions. In this article, I have mainly surveyed the exact EISA process by considering the difference between simple and controlled EISA processes on the basis of my own experiments. I believe that the insights are consequently helpful for obtaining highly ordered mesoporous materials with demanded morphologies.

Liquid-phase exfoliation of expanded graphites into graphene nanoplatelets using amphiphilic organic molecules

Graphenes with a two-dimensional lattice of carbons have been widely employed in diverse applications owing to their excellent electrical, thermal, mechanical, and gas-barrier properties. However, the frequently-used reduced graphene oxide (rGO), which is synthesized from natural graphites by strong oxidation and subsequent reduction via highly toxic components, exhibits imperfect characteristics because of remaining defect sites on its basal planes. Therefore, in this work, we present a convenient way to prepare graphene nanoplatelets (GNPs) with minimized defect sites on their basal planes employing liquid-phase exfoliation of edge-functionalized expanded graphites (EGs) with amphiphilic organic molecules. Exfoliated GNPs revealed approximately sub-7-nm-thickness and showed stable dispersibility in an organic media during 9months. Furthermore, spray-coated GNP films presented homogeneously stacked morphologies without noticeable agglomerations.

Selective adsorption and chiral amplification of amino acids in vermiculite clay-implications for the origin of biochirality

Smectite clays are hydrated layer silicates that, like micas, occur naturally in abundance. Importantly, they have readily modifiable interlayer spaces that provide excellent sites for nanochemistry. Vermiculite is one such smectite clay and in the presence of small chain-length alkyl-NH3Cl ions, forms sensitive, 1-D ordered model clay systems with expandable nano-pore inter-layer regions. These inter-layers readily adsorb organic molecules. N-propyl NH3Cl vermiculite clay gels were used to determine the adsorption of alanine, lysine and histidine by chiral HPLC. The results show that during reaction with fresh vermiculite interlayers, significant chiral enrichment of either L- and D-enantiomers occurs depending on the amino acid. Chiral enrichment of the supernatant solutions is up to about 1% per pass. In contrast, addition to clay interlayers already reacted with amino acid solutions resulted in little or no change in D/L ratio during the time of the experiment. Adsorption of small amounts of amphiphilic organic molecules in clay inter-layers is known to produce Layer-by-Layer or Langmuir-Blodgett films. Moreover atomistic simulations show that self-organization of organic species in clay interlayers is important. These non-centrosymmetric, chirally active nanofilms may cause clays to act subsequently as chiral amplifiers, concentrating organic material from dilute solution and having different adsorption energetics for D- and L-enantiomers. The additional role of clays in RNA oligimerization already postulated by Ferris and others, together with the need for the organization of amphiphilic molecules and lipids noted by Szostak and others, suggests that such chiral separation by clays in lagoonal environments at normal biological temperatures might also have played a significant role in the origin of biochirality.

Effects of Atmospherically Important Solvated Ions on Organic Acid Adsorption at the Surface of Aqueous Solutions

The effects of salts on the solubility of amphiphilic organic molecules are of importance to numerous atmospheric, environmental, and biological systems. A detailed picture of the influence of dissolved atmospheric salts, NaCl and Na(2)SO(4), on the adsorption of hexanoic acid at the vapor/water interface is developed using vibrational sum-frequency spectroscopy and surface tension measurements as a function of time, organic concentration, and solution pH. We have found that for hexanoic acid adsorption at the vapor/water interface, a fast initial adsorption is followed by two considerably slower processes: a reorientation of the polar headgroup and a restructuring of the headgroup solvation shell. The addition of salts affects this restructuring by reducing the range of water--headgroup interactions immediately upon surface adsorption for ion containing solutions. Reorientation of the organic headgroup with time occurs at the surface of both salt-containing and salt-free solutions, but the most stable orientation differs with the added ions. The dissolved salts also enhance the interfacial concentration of hexanoic acid, consistent with the known salting-out behavior of Cl(-) and SO(4)(2-) anions.

Effect of surfactant in a modified sol on the physicochemical properties and photocatalytic activity of crystalline TiO2 nanoparticles

This study describes the effect of amphiphilic organic molecules (surfactants) in a sol on the physicochemical properties and photocatalytic activity of crystalline TiO2 nanoparticles prepared via a simple sol–gel route at high temperatures from 400 to 800 °C. Addition of polyoxyethylenesorbitan surfactant and polyethylene oxide and polypropylene oxide triblock copolymer as particle size inhibitors and pore directing agents into a stable titania sol affected the physicochemical properties of TiO2 nanoparticles such as their crystallographic structure, morphology, and defect structure. With the addition of the surfactants, the ratio of anatase and rutile crystal phases of TiO2 was controlled and an active anatase crystal phase was maintained during heat treatment up to 800 °C. Decrease in the sintering rate and inhibition in crystal growth were also observed, which resulted in higher surface area and inhibition of crystallite aggregation. Bulk defects in TiO2 were reduced while surface defects were increased as a result of the addition of surfactants. These physicochemical properties of TiO2 nanoparticles were correlated with photocatalytic degradation of 4-chlorophenol in water. The results revealed that high crystallinity, anatase crystal phase, high specific surface area, surface defects, and segregated morphology of TiO2 nanoparticles, which were induced by the addition of surfactants, were more advantageous for enhancing photocatalytic destruction of the model organic compound tested in the study.

A nanohybrid membrane with lipid bilayer-like properties utilized as a conductimetric saccharin sensor

Since their introduction, artificial lipid bilayer membranes were used in a wide array of applications, such as sensors, biocompatible materials and study-models of the cell's outer boundary. Here, we present a nanohybrid membrane using an inorganic host and amphiphilic organic molecules with lipid bilayer-like properties. The stability of the presented mimetic membrane is significantly improved when compared to existing methods. The nanohybrid membrane exhibited two thermotropic phases corresponding to the Lα and Lβ phases that lipid bilayer membranes are known to adopt. Integration of cholesterol molecules into the nanohybrid membrane lead to the same qualitative effects as in lipid bilayers, including expansion of the bilayer spacing and decrease of the Lα to Lβ transition enthalpy. To further illustrate the similarities of the synthesized membrane with a lipid bilayer, the ability of the nanohybrid membrane to function as saccharin conductimetric sensor was evaluated. The lower limit of detection of the sensor was 6μM and the linear range of response was from 20 to 400μM.

Microemulsions as microreactors in physical organic chemistry

Abstract Microemulsions are very versatile reaction media which nowadays find many applications, ranging from nanoparticle templating to preparative organic chemistry. The thermodynamically stable and microheterogeneous nature of microemulsions, used as reaction media, induces drastic changes in the reagent concentrations, and this can be specifically used for tuning the reaction rates. In particular, amphiphilic organic molecules can accumulate and orient at the oil-water interface, inducing regiospecificity in organic reactions. In this review, we will show the recent tendencies of the use of microemulsions as organic reaction media.

Mechanism of Hydroxyapatite Mineralization in Biological Systems(Review)

The formation process of inorganic crystals in biological systems (biomineralization) is the fruitage of an extended period of fine-tuning by evolution and is replete with material scientific key considerations. In this article, our recent attempts to elucidate the mineralization mechanism of hydroxyapatite (HAp) in natural bodies are described. It has been known that inorganic crystals precipitate onto organic matrix surfaces in biomineralization processes. Amphiphilic organic molecules assembled to monolayer films were employed to reproduce the organic matrices and the HAp precipitation process onto the monolayers were subjected to spectroscopic and structural analyses. We also determined the interfacial atomic structure of HAp {100} facet by using high-resolution transmission electron microscopy. A mechanism of HAp mineralization was proposed in view of the experimental results to determine the underlying reasons for refinement in structures of biominerals.

Hexagonal Nanoporous Germanium Through Surfactant‐Driven Self‐Assembly of Zintl Clusters.

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Hexagonal nanoporous germanium through surfactant-driven self-assembly of Zintl clusters

Surfactant templating is a method that has successfully been used to produce nanoporous inorganic structures from a wide range of oxide-based material. Co-assembly of inorganic precursor molecules with amphiphilic organic molecules is followed first by inorganic condensation to produce rigid amorphous frameworks and then, by template removal, to produce mesoporous solids. A range of periodic surfactant/semiconductor and surfactant/metal composites have also been produced by similar methods, but for virtually all the non-oxide semiconducting phases, the surfactant unfortunately cannot be removed to generate porous materials. Here we show that it is possible to use surfactant-driven self-organization of soluble Zintl clusters to produce periodic, nanoporous versions of classic semiconductors such as amorphous Ge or Ge/Si alloys. Specifically, we use derivatives of the anionic Ge9(4-) cluster, a compound whose use in the synthesis of nanoscale materials is established. Moreover, because of the small size, high surface area, and flexible chemistry of these materials, we can tune optical properties in these nanoporous semiconductors through quantum confinement, by adsorption of surface species, or by altering the elemental composition of the inorganic framework. Because the semiconductor surface is exposed and accessible in these materials, they have the potential to interact with a range of species in ways that could eventually lead to new types of sensors or other novel nanostructured devices.

Hierarchically helical mesostructured silica nanofibers templated by achiral cationic surfactant

Recently, ordered chiral mesoporous silica with a twisted hexagonal rod-like morphology and hexagonally ordered chiral channels has been synthesized by using chiral anionic surfactants as a liquid crystal template (S. Che, Z. Liu, T. Ohsuna, K. Sakamoto, O. Terasaki and T. Tatsumi, Nature, 2004, 429, 281). In this work, we report an observation of hierarchically helical mesoporous silica nanofibers organized by the achiral cationic surfactant cetyltrimethylammonium bromide (CTAB). These nanofibers (diameter ranging around 100–300 nm) grew from a two-phase system (H2O, CTAB, HCl for the aqueous phase and tetraethylsiloxane (TEOS) in hexane for the oil phase). SEM and TEM characterizations were performed and the results indicate that these nanofibers possess rope-like twisted hexagonal morphology and helical (chiral) mesoporous channels running inside winding around the fiber axis. These twisted hexagonal nanofibers could further curve spirally to form a second-level helical morphology (hierarchically helical morphology). As no chiral molecules are used in the synthesis, the hierarchically helical morphology of nanofibers could be explained by the different kinds of topological defects existing in the silicate liquid crystal seeds formed in a diffusion-controlled kinetic process, and these defects could initiate and direct the growth of particular forms of mesostructured silica. Formation of the ordered chiral mesorporous silica would be expected to be a general phenomenon in the cooperative assembly between amphiphilic organic molecules (templates) and inorganic species, no matter whether the templates are chiral or achiral.