Decyltrimethylammonium Bromide Research Articles

Impact of Different Surfactants and their Mixtures on Methane‐Hydrate Formation

AbstractGas hydrates can be used as a potential means for natural gas storage. Design of a gas‐hydrate‐based unit requires accurate knowledge of hydrate‐formation kinetics especially in the presence of promoters. In this study, the effects of sodium dodecyl sulfate (SDS), hexa decyl trimethyl ammonium bromide (HTABr), polyoxy ethylene(20) cetyl ether (Brij‐58) and mixtures of SDS with HTABr and Brij‐58 have been investigated to determine their influence on the methane‐hydrate‐formation kinetics and thermodynamics. The study on the kinetics of hydrate formation is focused on the induction time and hydrate‐formation rate. It is found that induction time of hydrate formation in the presence of a promoter is reduced considerably for each test compared with a pure water test. The minimum value of the induction time is found for a mixture of SDS (500 ppm) with HTABr (700 ppm). All of the surfactants and their mixtures can be designated as hydrate‐formation promoters in the concentration ranges studied in the present work and can increase the hydrate‐formation rate. SDS at a concentration of 500 ppm is determined to be the best hydrate‐formation promoter among the surfactants tested. The percent conversion of methane to hydrate is increased in the presence of these surfactants at the end of hydrate formation. The maximum value of the conversion is observed for the 500 ppm concentration of SDS. The results demonstrate that these surfactants and their corresponding mixtures have no significant effect on the thermodynamics of methane hydrate formation.

An economic method for synthesis of highly ordered porous silica

We report an economic method for synthesis of highly ordered silica with a mixing surfactant system containing short-chain cationic surfactant (decyltrimethyl ammonium bromide, denoted C10TMAB) and short-chain anionic surfactant (sodium octyl sulfate, denoted SOS) as the templating agents. Highly ordered supermicroporous silica was synthesized by judiciously chosen mixing ratio of surfactants. The samples were characterized by small-angle X-ray diffraction, transmission electron microscopy, and N2 adsorption–desorption. The results showed that the pore structure of the resulting silica belongs to the two-dimensional hexagonal structure (space group 2D-p6mm) with a pore size of ca. 2.2nm. Moreover, the method proposed herein is expected to facilitate the synthesis of not only porous silicas but also materials with other framework compositions.

Investigation of factors that affect cationic surfactant loading on activated carbon and perchlorate adsorption

Five cationic surfactants were employed to modify activated carbon for the purpose of comparing the impacts of surfactant properties and operational parameters on modification. Surfactants under study included cetylpyridinium chloride monohydrate (CPC), hexadecyltrimethylammonium bromide (HDTMA), cetyltrimethylammonium chloride (CTAC), myristyltrimethylammonium bromide (MTAB), and decyltrimethylammonium bromide (DTAB). Results revealed that, properties of surfactants (critical micelle concentration, chemical configuration), initial loading concentration, pH of solution and carbon type all had significant impacts on surfactant loading. In general, surfactants with smaller micelle structures were more easily loaded than those with larger micelles. For all cationic surfactants tested here, loading is optimal around neutral pH. After surfactant loading, activated carbon presented a much positively charged surface and this is manifested in obvious improvement in perchlorate adsorption. Perchlorate was mainly adsorbed through ion exchange with surfactant-loaded activated carbon.

Monodisperse spherical mesoporous silica particles: fast synthesis procedure and fabrication of photonic-crystal films

A procedure for the synthesis of monodisperse spherical mesoporous silica particles (MSMSPs) via the controlled coagulation of silica/surfactant clusters into spherical aggregates with mean diameters of 250–1500 nm has been developed. The synthesis is fast (taking less than 1 h) because identical clusters are simultaneously formed in the reaction mixture. The results of microscopic, x-ray diffraction, adsorption and optical measurements allowed us to conclude that the clusters are ∼15 nm in size and have hexagonally packed cylindrical pore channels. The channel diameters in MSMSPs obtained with cethyltrimethylammonium bromide and decyltrimethylammonium bromide as structure-directing agents were 3.1 ± 0.15 and 2.3 ± 0.12 nm, respectively. The specific surface area and the pore volume of MSMSP were, depending on synthesis conditions, 480–1095 m2 g−1 and 0.50–0.65 cm3 g−1. The MSMSP were used to grow opal-like photonic-crystal films possessing a hierarchical macro-mesoporous structure, with pores within and between the particles. A selective filling of mesopore channels with glycerol, based on the difference between the capillary pressures in macro- and mesopores, was demonstrated. It is shown that this approach makes it possible to control the photonic bandgap position in mesoporous opal films by varying the degree of mesopore filling with glycerol.

Is the Activation Gate Closed in Kv Channel Closed-State Inactivation?

Kv4.x channel complexes including auxiliary subunits such as DPP6-S and KChIP1 undergo preferential closed-state inactivation (CSI; Baehring and Covarrubias, 2011, J Physiol, 589.3:461-479; Fineberg et al., 2012, J Gen Physiol, in press). However, the molecular basis of CSI in Kv4.x channels remains poorly understood. A key unanswered question of this problem is whether the channel's activation is actually closed, as CSI implies. We have previously proposed that CSI results when the activated channel fails to open or simply prefers to close. This hypothesis specifically suggests that the intracellular activation gate may adopt a stable closed conformation, even under depolarized conditions that would initially favor the activated “up” state of the voltage sensors. To test this hypothesis, we are exploiting the trapping paradigm previously investigated by Holmgren et al. to test the state of the intracellular activation gate (1997, J Gen Physiol, 109:527-535). Essentially, if the activation gate closes behind a quaternary ammonium (QA) blocker inside the pore, the blocker cannot exit the pore; effectively, it is trapped. We are expressing the ternary Kv4.1/I400C channels (this mutation favors trapping) including DPP6-S and KChIP1 in Xenopus oocytes. Then, in the inside-out patch-clamp configuration, we are using a computer-controlled perfusion system to deliver the QA derivative decyltrimethylammonium bromide (C10) to the bath and probe the ability of the channel's activation gate to trap C10 in the closed, open and inactivated states. Preliminary results show that the trapping paradigm may yield an answer to the central question of this study. If the activation gate is indeed closed during CSI, C10 trapping will only occur when the drug is applied to the conducting channel, but no trapping of C10 will be observed in the closed and inactivated states. Supported by NIH grant R01 NS032337 (MC).

Development of ethosome-like catanionic vesicles for dermal drug delivery

A carrier for enhanced skin delivery of drugs has ever been discovered and named “ethosomes,” which are phospholipid vesicular systems embodying ethanol in relatively high concentrations. This work aims at developing competent ethosome-like catanionic vesicles for dermal drug delivery. The preparation of double-chained catanionic surfactant (or ion-pair-amphiphile, IPA) DeTMA-DS from single-chained cationic surfactant (decyltrimethylammonium bromide, DeTMAB) and anionic surfactant (sodium dodecyl sulfate, SDS) by the precipitation method was demonstrated first. This lipid-like surfactant was thereafter used as the material to prepare the catanionic vesicles with the aid of ethanol as the cosolvent in aqueous buffer solution by a simple semispontaneous process. Formability and physical stability of the as-prepared catanionic vesicles were discussed based on the viewpoint of mixed solvent dielectric constant. The potential application of the catanionic vesicles as nano-carriers in dermal drug delivery was demonstrated by the encapsulation of vitamin E acetate (α-tocopherol acetate, α-TA). Furthermore, effects of cholesterol addition on physical stability, bilayer membrane rigidity, and encapsulation efficiency of the catanionic vesicles with 20% ethanol, in which the most stable vesicle can be formed, was systematically studied. The experimental results revealed that vesicle stability can be enhanced further by the addition of cholesterol. The vesicle membrane rigidity and encapsulation efficiency are both increased with the increase of cholesterol addition. It is, therefore, suggested that the encapsulation efficiency of α-TA in the catanionic vesicles is dependent on the vesicle membrane rigidity. Finally, the results of gelation of catanionic vesicles by a water soluble polymer with hydrophobical modification were also reported and the role played by the vesicular bilayer rigidity in the interaction between catanionic vesicles and polymer molecules were discussed. The phase maps and the rheological properties obtained for mixtures of catanionic vesicles and polymer molecules may provide useful information for practical use of the catanionic vesicles in dermal delivery of drugs.

Novel method to synthesize and characterize Zinc Sulfide nanoparticles

Zinc sulfide nanoparticles were fabricated by solvent evaporation method with and without using capping agent, Hexa decyltrimethyl ammonium bromide (CTAB) at room temperature. The product was received in powder form. The structure and composition of the resultant product was characterized by means of UV and FTIR spectrophotometric studies. FTIR analysis showed peaks at 352.02 cm -1 and 611.46 cm -1 for Zinc Sulfide with CTAB, corresponding to Zinc and Sulfide stretching. For Zinc Sulfide without CTAB, the same stretching frequencies were observed at 315.10 cm -1 and 615.32 cm -1 . UV spectrophotometer study determined the band gap of nanocrystalline Zinc Sulfide (with and without CTAB) as 5.48 eV and 5.99 eV, respectively. The optical absorption edge exhibited a blue shift with respect to that of the bulk sample. The blue shift with the decrease in crystalline size was attributed to the quantum size effects. When ZnS was prepared without CTAB, there was decrease in the size of the nanoparticle than when it was prepared with CTAB. Even though no capping agent (CTAB) was used in preparing ZnS, the particle size was well reduced. It was achieved by stirring the solutions during preparation. No

SURFACTANT-ASSISTED SOL-GEL AUTO-COMBUSTION SYNTHESIS OF SR-HEXAFERRITE NANOPOWDER USING DIFFERENT FUELS AND BASIC AGENTS

In this research Sr -hexaferrite powder was synthesized by a sol–gel auto-combustion route using two different fuels (glycine and citric acid) and two different basic agents (ammonia and trimethylamine). N -decyltrimethylammonium bromide ( C 13 H 30 BrN ) was also employed as a cationic surfactant. The results showed the finest crystallite size and the lowest calcination temperature have been obtained as 27.2 nm and 800 °C respectively, in the presence of citric acid, trimethylamine and surfactant.

Comparative analysis of genomic DNA isolation procedures; hexa decyltrimethylammonium bromide (CTAB) and liquid detergent (morning fresh) methods from Samsorg 41 (icsv 400)

Genomic DNA was prepared from germinating seeds of a variety of sorghum in Nigeria (Samsorg 41) using two different isolation protocols (CTAB and morning fresh® method). Highest quantity of DNA was obtained from Samsorg 41 using the morning fresh® method. Genomic DNA obtained using this method had a much lower purity as compared with that obtained using the CTAB method. Both methods produced genomic DNA of high integrity with minimum shearing. Key words: Genomic DNA, CTAB, morning fresh®, isolation, Samsorg 41, Nigeria.

A Bioassay for the Detection of Perchlorate in the ppb Range

A bioassay for the determination of ppb (μg·L(-1)) concentrations of perchlorate has been developed and is described herein. The assay uses the enzyme perchlorate reductase (PR) from the perchlorate-reducing organism Dechloromonas agitata in purified and partially purified forms to detect perchlorate. The redox active dye phenazine methosulfate (PMS) is shown to efficiently shuttle electrons to PR from NADH. Perchlorate can be determined indirectly by monitoring NADH oxidization by PR. To lower the detection limit, we have shown that perchlorate can be concentrated on a solid-phase extraction (SPE) column that is pretreated with the cation decyltrimethylammonium bromide (DTAB). Perchlorate is eluted from these columns with a solution of 2 M NaCl and 200 mM morpholine propane sulfonic acid (MOPS, pH 12.5). By washing these columns with 15 mL of 2.5 mM DTAB and 15% acetone, contaminating ions, such as chlorate and nitrate, are removed without affecting the bioassay. Because of the effect of complex matrices on the SPE columns, the method of standard additions is used to analyze tap water and groundwater samples. The efficacy of the developed bioassay was demonstrated by analyzing samples from 2-17000 ppb in deionized lab water, tap water, and contaminated groundwater.

Osmotic and Activity Coefficients of Trimethyloctylammonium Bromide and Decyltrimethylammonium Bromide in Aqueous Solutions as a Function of Temperature

Osmotic coefficients of aqueous solutions of trimethyloctylammonium bromide and decyltrimethylammonium bromide were measured by the isopiestic method at the following temperatures: 298.15, 293.15, 288.15 and 283.15 K. Activity coefficients of the solutes were calculated from the osmotic coefficients. The results were compared with the Debye-Huckel limiting law and analyzed according to their variation with the alkyl chain length of the cation and with the change in temperature.

Structural investigation of viscoelastic micellar water/CTAB/NaNO3 solutions

A highly viscoelastic worm-like micellar solution is formed in hexa- decyltrimethylammonium bromide (CTAB) in the presence of sodium nitrate (NaNO3). A gradual increase in micellar length with increasing NaNO3 was assumed from the rhe- ological measurements where the zero-shear viscosity (·0) versus NaNO3 concentration curve exhibits a maximum. However, upon increase in temperature, the viscosity de- creases. Changes in the structural parameters of the micelles with addition of NaNO3 were inferred from small angle neutron scattering measurements (SANS). The intensity of scattered neutrons in the low q region was found to increase with increasing NaNO3 concentration. This suggests an increase in the size of the micelles and/or decrease of intermicellar interaction with increasing salt concentration. Analysis of the SANS data using prolate ellipsoidal structure and Yukawa form of interaction potential between mi- celles indicate that addition of NaNO3 leads to a decrease in the surface charge of the ellipsoidal micelles which induces micellar growth. Cryo-TEM measurements support the presence of thread-like micelles in CTAB and NaNO3.

Study of the binding between lysozyme and C 10-TAB: Determination and interpretation of the partial properties of protein and surfactant at infinite dilution

This work examines the binding in aqueous solution, through the experimental determination of specific volumes and specific adiabatic compressibility coefficients, of decyltrimethylammonium bromide to lysozyme and to non-charged polymeric particles (which have been specially synthesized by emulsion polymerization). A method was developed to calculate the specific partial properties at infinite dilution and it was shown that a Gibbs–Duhem type equation holds at this limit for two solutes. With this equation, it is possible to relate the behavior of the partial properties along different binding types at a constant temperature. It was found that the first binding type, specific with high affinity, is related to a significant reduction of surfactant compressibility. The second binding type is accompanied by the unfolding of the protein and the third one is qualitatively identical to the binding of the surfactant to non-charged polymeric particles.

Discovery of synergistic permeation enhancers for oral drug delivery

Oral drug delivery offers an attractive method of needle-free drug administration. Unfortunately, oral delivery is often hampered by the poor permeability of drugs across the intestinal epithelium. Although several single chemical permeation enhancers have been shown to alleviate permeability difficulties, this often occurs at the expense of safety. This in vitro study demonstrates the use of binary and ternary combinations of permeation enhancers to create synergistic enhancer formulations (SEFs) that offer a high level of potency while inducing very little toxicity in Caco-2 cells. Although relatively rare in the explored formulation space, SEFs were abundant enough to significantly increase the repertoire of permeation enhancers that are safe and effective in vitro. The most promising enhancers from the binary study led to easily identifiable ternary SEFs, thus increasing the efficiency of the discovery process. Some of the best performers of the study included binary combinations of hexylamine and chembetaine and ternary combinations of sodium laureth sulfate, decyltrimethyl ammonium bromide, and chembetaine, all at a total concentration of 0.1% (w/v). Furthermore, several SEFs were shown to be capable of increasing mannitol and 70 kDa dextran permeability across Caco-2 monolayers 15- and 8-fold, respectively. These results encourage further exploration of several leading formulations for in vivo applications in oral drug delivery.

NEW PROBES FOR SURFACTANT SOLUTIONS: PHOSPHORESCENT LABELLED DETERGENTS

— A series of alkyltrimethylammonium bromides containing terminal phosphorescent chromo-phores have been prepared and characterized. 10-(4-bromo, l-naphthoyl)decyltrimethylammonium bromide(BND–10) has a critical micelle concentration (CMC) of 14 mM and a micellar mean aggregation number () of 105. Analogous detergents,BND–11, -8, and -5 have also been prepared; in each case, the naphthoyl group is located at the terminal carbon of an alkyl chain of the indicated length. The normal behavior of increasing and decreasing CMC with increasing aliphatic chain length is observed. When compared with unsubstituted alkyltrimethylammonium bromides, the 4-bromo, 1-naphthoyl chromo-phore is roughly equivalent to 6 methylenes with respect to hydrophobic contribution. A broad phosphorescence maximizing at about 590 nm is readily detected upon photoexcitation of the BND molecules in various solvents. The weak fluorescence of the probes is consistent with efficient intersystem crossing of the BND molecules. BND–10 has a phosphorescence yield of 0.023 and a lifetime of 1 ms in water at 250C. The probes are useful for the study of micelle-detergent exchange dynamics.

Morphology and photoluminescence of colloidal polypyrrole nanoparticles

In order to elucidate the origin of the photoluminescence (PL) of polypyrrole (PPy) colloids, several PPy colloidal samples were prepared under various emulsifying conditions and their PL properties were correlated with the particle morphologies. While highly aggregated fibril- or sheet-like PPy particles were obtained when a cationic surfactant [decyltrimethyl ammonium bromide (DeTAB)] and metal halide oxidant (CuCl 2) were used, employment of anionic surfactant and non-metallic oxidant [sodium di(2-ethyl-1-hexyl)sulfosuccinate (DEHSNa) and ammonium persulfate (APS)] afforded spherical PPy nanoparticles with more regularity. PL measurements of these samples indicated that the highest PL intensity is obtained from the less aggregated and smaller PPy nanoparticles. It was presumed that the smaller particles generate more localized excitons due to shorter π-conjugation length, thereby resulting in stronger PL intensity.

Surface and bulk properties of aqueous decyltrimethylammonium bromide–hexadecyltrimethylammonium bromide mixed system

The aqueous mixed system decyltrimethylammonium bromide (C 10TAB)–hexadecyltrimethylammonium bromide (C 16TAB) was studied by conductivity, ion-selective electrodes, surface tension, and fluorescence spectroscopy techniques. The mixture critical micelle concentration, cmc*, aggregation number, N ∗ , and micelle molar conductivity, Λ M cmc , showed that the system aggregation is strongly nonideal. Both cmc* and N ∗ results were analyzed with two different procedures: (i) the regular solution theory on mixed micelles or Rubingh's theory, and (ii) by the determination of the partial critical micelle concentration of the amphiphile component i in the presence of a constant concentration of the other amphiphile component, cmc i ∗ . The Rubingh procedure gives micelles richer in C 16TAB than the overall mixtures, while procedure (ii) gives micelles having the same composition as in the complete surfactant mixture ( α C 10 TAB ). Mixed micelles are larger than pure surfactant ones, with nonspherical shape. Using a literature model, the cause of the synergistic effect seems to be a reduction of the hydrocarbon/water contact at the micelle surface when mixed micelles form. Conductivity and ion-selective electrodes indicate that highly ionized premicelles form immediately before the cmc*. The air/solution interface is strongly nonideal and much richer in C 16 TAB than the composition in the bulk. When micelles form there is a strong desorption from the air/solution interface because micelles are energetically favored when compared with the monolayer.

Synthesis and Layer‐by‐Layer Deposition of Spherical Poly(3,4‐ethylenedioxythiophene) Nanoparticles ‐ Toward Fast Switching Times between Reduced and Oxidized States

AbstractA microemulsion polymerization for the synthesis of poly(3,4‐ethylenedioxythiophene) (PEDOT) nanoparticles is described. Spherical and electrically conducting PEDOT particles with diameters as small as 27 ± 8 nm were obtained by using decyltrimethylammonium bromide as a cationic surfactant. PEDOT nanoparticle multilayers, alternated with poly(styrene sulfonate), were prepared by the layer‐by‐layer deposition technique. Electrochemical surface plasmon resonance experiments revealed a ten‐fold increase in the switching time between redox states as compared with Baytron P/poly(ethyleneimine) multilayers. The enhanced charge transport can be attributed to an improved diffusion of the charge‐balancing counterions into the PEDOT nanoparticles.magnified image

Self-Aggregation of Ionic C10 Surfactants Having Different Headgroups with Special Reference to the Behavior of Decyltrimethylammonium Bromide in Different Salt Environments: A Calorimetric Study with Energetic Analysis

Self-aggregation of C10 ionic surfactants with different head groups, viz., decylpyridinium chloride, sodium decylsulfate, decylammonium bromide, decyldimethylammonium bromide, and decyltrimethylammonium bromide, was studied in the aqueous medium by microcalorimetric and conductometric methods. The effects of temperature and different salts (NaF, NaCl, NaBr, NaI, Na2SO4, Na2S2O7, Na-benzoate, and Na-salicylate) were also studied on decyltrimethylammonium bromide representatives. The cmc, counterion binding, and energetics of micellization were evaluated and discussed. The energetic parameters, enthalpy, entropy, and specific heat of micellization obtained from direct calorimetry and the indirect van't Hoff method were compared and discussed.

Density, Kinematic Viscosity, Speed of Sound, and Surface Tension of Hexyl, Octyl, and Decyl Trimethyl Ammonium Bromide Aqueous Solutions

Density, kinematic viscosity, surface tension, and speed of sound of hexyl, octyl, and decyl trimethylammonium bromide aqueous solutions have been determined. The influence of each surfactant concentration upon these physical properties has also been studied at 298 K. The experimental values of these physical properties have been employed to determine the critical micellar concentration for each surfactant as well as to analyze the effect of chain length upon this characteristic parameter.