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Sample records for surfactant micelles affects

  1. Liquid crystalline states of surfactant solutions of isotropic micelles

    International Nuclear Information System (INIS)

    Bagdassarian, C.; Gelbart, W.M.; Ben-Shaul, A.

    1988-01-01

    We consider micellar solutions whose surfactant molecules prefer strongly to form small, globular aggregates in the absence of intermicellar interactions. At sufficiently high volume fraction of surfactant, the isotropic phase of essentially spherical micelles is shown to be unstable with respect to an orientationally ordered (nematic) state of rodlike aggregates. This behavior is relevant to the phase diagrams reported for important classes of aqueous amphiphilic solutions

  2. Critical micelle concentration values for different surfactants measured with solid-phase microextraction fibers

    NARCIS (Netherlands)

    Haftka, Joris J H; Scherpenisse, Peter; Oetter, G??nter; Hodges, Geoff; Eadsforth, Charles V.; Kotthoff, Matthias; Hermens, Joop L M

    The amphiphilic nature of surfactants drives the formation of micelles at the critical micelle concentration (CMC). Solid-phase microextraction (SPME) fibres were used in the present study to measure CMC values of twelve nonionic, anionic, cationic and zwitterionic surfactants. The SPME derived CMC

  3. Effects of surfactant micelles on viscosity and conductivity of poly(ethylene glycol) solutions

    Science.gov (United States)

    Wang, Shun-Cheng; Wei, Tzu-Chien; Chen, Wun-Bin; Tsao, Heng-Kwong

    2004-03-01

    The neutral polymer-micelle interaction is investigated for various surfactants by viscometry and electrical conductometry. In order to exclude the well-known necklace scenario, we consider aqueous solutions of low molecular weight poly(ethylene glycol) (2-20)×103, whose radial size is comparable to or smaller than micelles. The single-tail surfactants consist of anionic, cationic, and nonionic head groups. It is found that the viscosity of the polymer solution may be increased several times by micelles if weak attraction between a polymer segment and a surfactant exists, ɛmicelles. Even though ɛ is small, the interaction energy between a macromolecule and a micelle can be a few kBT due to many contacts, and thus leads to polymer adsorption on micelles' surfaces. The rapid growth of the viscosity with surfactant concentration is therefore attributed to the considerable cross links among micelles and polymers (transient network). In addition to substantial alteration of the transport properties, this weak interaction also influences the onset point of thermodynamic instability associated with polymer-surfactant solutions. The examples include the decrease of critical aggregation concentration for ionic surfactant and clouding point for nonionic surfactant due to PEG addition.

  4. Photophysical study of a charge transfer oxazole dye in micelles: Role of surfactant headgroups

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, Jyotirmay [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India); Sarkar, Yeasmin; Parui, Partha Pratim [Department of Chemistry, Jadavpur University, Kolkata 700032 (India); Chakraborty, Sandipan [Department of Microbiology, University of Calcutta, Kolkata 700019 (India); Biswas, Suman [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India); Das, Ranjan, E-mail: ranjan.das68@gmail.com [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India)

    2015-07-15

    Photophysics of 5-(4′′-dimethylaminophenyl)-2-(4′-sulfophenyl)oxazole, sodium salt (DMO) which undergoes intramolecular charge transfer in the excited state was studied in micelles. In the cationic and the nonionic micelles, significantly higher fluorescence quantum yield is observed in comparison to the anionic micelles, due to much lower accessibility of DMO to the water molecules in the former micelles than the latter. Time-resolved fluorescence decays were characterized by a fast (τ{sub 1}) and a slow (τ{sub 2}) component of decay in all the micelles. The fast decay component (τ{sub 1}) increases significantly in going from the anionic micelles to the cationic micelles, because of the poorly hydrated headgroup region of the latter micelles compared to the former. Furthermore, much higher value of the slow component of decay (τ{sub 2}) is observed for the cationic and the neutral micelles than the anionic micelles. This is attributed to the increased penetration of water molecules into the micellar core of the anionic micelles compared to the cationic and the neutral micelles. - Highlights: • Photophysics of the fluorophore are remarkably different in the cationic and the anionic micelles. • Differential hydration of the surfactant headgroups gives rise to significantly different fluorescence quantum yield and lifetime in oppositely charged micelles. • Electrostatic interactions fine tune location of the fluorophore in the micelle–water interface of ionic micelles.

  5. Persistence length of wormlike micelles composed of ionic surfactants: self-consistent-field predictions

    NARCIS (Netherlands)

    Lauw, Y.; Leermakers, F.A.M.; Cohen Stuart, M.A.

    2007-01-01

    The persistence length of a wormlike micelle composed of ionic surfactants CnEmXk in an aqueous solvent is predicted by means of the self-consistent-field theory where CnEm is the conventional nonionic surfactant and X-k is an additional sequence of k weakly charged (pH-dependent) segments. By

  6. Structure formation in binary mixtures of surfactants: vesicle opening-up to bicelles and octopus-like micelles

    Science.gov (United States)

    Noguchi, Hiroshi

    Micelle formation in binary mixtures of surfactants is studied using a coarse-grained molecular simulation. When a vesicle composed of lipid and detergent types of molecules is ruptured, a disk-shaped micelle, the bicelle, is typically formed. It is found that cup-shaped vesicles and bicelles connected with worm-like micelles are also formed depending on the surfactant ratio and critical micelle concentration. The obtained octopus shape of micelles agree with those observed in the cryo-TEM images reported in [S. Jain and F. S. Bates, Macromol. 37, 1511 (2004).]. Two types of connection structures between the worm-like micelles and the bicelles are revealed.

  7. Interactions of short chain phenylalkanoic acids within ionic surfactant micelles in aqueous media

    Directory of Open Access Journals (Sweden)

    Naeem Kashif

    2012-01-01

    Full Text Available % SDS KR nema Solubilization and interactions of phenylalkanoic acids induced by cationic surfactant, cetyltrimethylammonium bromide (CTAB and an anionic surfactant, sodium dodecyl sulfate (SDS was investigated spectrophotometrically at 25.0°C. The UV spectra of the additives (acids were measured with and without surfactant above and below critical micelle concentration (cmc of the surfactant. The presence of alkyl chain in phenylalkanoic acids is responsible for hydrophobic interaction resulting in shift of the spectra towards longer wavelength (red shift. The value of partition coefficient (Kx between the bulk water and surfactant micelles and in turn standard free energy change of solubilization (ΔGpº were also estimated by measuring the differential absorbance (ΔA of the additives in micellar solutions.

  8. pH dependent fluorescence switching in salicylideneaniline: ‘off–on–off’ operation controlled by surfactant micelles

    Energy Technology Data Exchange (ETDEWEB)

    Das, Diganta Kumar, E-mail: digkdas@yahoo.com; Dutta, Kaku

    2014-01-15

    Salaniline, a condensation product of salicylaldehyde and aniline, shows “off–on” fluorescent behaviour with pH in 1:1 (v/v) CH{sub 3}CN:H{sub 2}O and when 3% (w/v) anionic sodium dodecylsulphate (SDS) surfactant is present. The fluorescent switch behaviour of salaniline is forced to “off–on–off” type by 3% (w/v) neutral triton X-100 (TX-100) and 3% (w/v) cationic cetyltrimethylammonium bromide (CTAB) surfactant. The fluorescent “on” window is observed in the pH range 8.0–12.5 for TX-100 and 7.0–11.0 for CTAB. Different charge nature of the surfactants affects the protonation/deprotonation behaviour of salaniline differently, hence the photoinduced electron transfer (PET) processes and the fluorescent switch behaviour. -- Highlights: • Salicylideneaniline act as pH dependent “off–on” fluorescent switch in 1:1 (v/v) CH{sub 3}CN:H{sub 2}O. • In surfactant micelles TX-100 (neutral) and CTAB (positive) make the fluorescent switch “off–on–off” type while in. • In surfactant micelle SDS (negative) the pH dependent fluorescent switch is “off–on” type.

  9. Micelle formation of nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate: surfactant chain length dependence of the critical micelle concentration.

    Science.gov (United States)

    Inoue, Tohru; Yamakawa, Haruka

    2011-04-15

    Micellization behavior was investigated for polyoxyethylene-type nonionic surfactants with varying chain length (C(n)E(m)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)). Critical micelle concentration (cmc) was determined from the variation of (1)H NMR chemical shift with the surfactant concentration. The logarithmic value of cmc decreased linearly with the number of carbon atoms in the surfactant hydrocarbon chain, similarly to the case observed in aqueous surfactant solutions. However, the slope of the straight line is much smaller in bmimBF(4) than in aqueous solution. Thermodynamic parameters for micelle formation estimated from the temperature dependence of cmc showed that the micellization in bmimBF(4) is an entropy-driven process around room temperature. This behavior is also similar to the case in aqueous solution. However, the magnitude of the entropic contribution to the overall micellization free energy in bmimBF(4) is much smaller compared with that in aqueous solution. These results suggest that the micellization in bmimBF(4) proceeds through a mechanism similar to the hydrophobic interaction in aqueous surfactant solutions, although the solvophobic effect in bmimBF(4) is much weaker than the hydrophobic effect. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Determination of the critical micelle concentration in simulations of surfactant systems.

    Science.gov (United States)

    Santos, Andrew P; Panagiotopoulos, Athanassios Z

    2016-01-28

    Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the "free" (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit).

  11. Biotoxicity and bioavailability of hydrophobic organic compounds solubilized in nonionic surfactant micelle phase and cloud point system.

    Science.gov (United States)

    Pan, Tao; Liu, Chunyan; Zeng, Xinying; Xin, Qiao; Xu, Meiying; Deng, Yangwu; Dong, Wei

    2017-06-01

    A recent work has shown that hydrophobic organic compounds solubilized in the micelle phase of some nonionic surfactants present substrate toxicity to microorganisms with increasing bioavailability. However, in cloud point systems, biotoxicity is prevented, because the compounds are solubilized into a coacervate phase, thereby leaving a fraction of compounds with cells in a dilute phase. This study extends the understanding of the relationship between substrate toxicity and bioavailability of hydrophobic organic compounds solubilized in nonionic surfactant micelle phase and cloud point system. Biotoxicity experiments were conducted with naphthalene and phenanthrene in the presence of mixed nonionic surfactants Brij30 and TMN-3, which formed a micelle phase or cloud point system at different concentrations. Saccharomyces cerevisiae, unable to degrade these compounds, was used for the biotoxicity experiments. Glucose in the cloud point system was consumed faster than in the nonionic surfactant micelle phase, indicating that the solubilized compounds had increased toxicity to cells in the nonionic surfactant micelle phase. The results were verified by subsequent biodegradation experiments. The compounds were degraded faster by PAH-degrading bacterium in the cloud point system than in the micelle phase. All these results showed that biotoxicity of the hydrophobic organic compounds increases with bioavailability in the surfactant micelle phase but remains at a low level in the cloud point system. These results provide a guideline for the application of cloud point systems as novel media for microbial transformation or biodegradation.

  12. Membrane-surfactant interactions. The role of surfactant in mitochondrial complex III-phospholipid-Triton X-100 mixed micelles

    International Nuclear Information System (INIS)

    Valpuesta, J.M.; Arrondo, J.L.; Barbero, M.C.; Pons, M.; Goni, F.M.

    1986-01-01

    Complex III (ubiquinol-cytochrome c reductase) was purified from beef heart mitochondria in the form of protein-phospholipid-Triton X-100 mixed micelles (about 1:80:100 molar ratio). Detergent may be totally removed by sucrose density gradient centrifugation, and the resulting lipoprotein complexes retain full enzyme activity. In order to understand the role of surfactant in the mixed micelles, and the interaction of Triton X-100 with integral membrane proteins and phospholipid bilayers, both the protein-lipid-surfactant mixed micelles and the detergent-free lipoprotein system were examined from the point of view of particle size and ultrastructure, enzyme activity, tryptophan fluorescence quenching, 31P NMR, and Fourier transform infrared spectroscopy. The NMR and IR spectroscopic studies show that surfactant withdrawal induces a profound change in phospholipid architecture, from a micellar to a lamellar-like phase. However, electron microscopic observations fail to reveal the existence of lipid bilayers in the absence of detergent. We suggest that, under these conditions, the lipid:protein molar ratio (80:1) is too low to permit the formation of lipid bilayer planes, but the relative orientation and mobility of phospholipids with respect to proteins is similar to that of the lamellar phase. Protein conformational changes are also detected as a consequence of surfactant removal. Fourier transform infrared spectroscopy indicates an increase of peptide beta-structure in the absence of Triton X-100; changes in the amide II/amide I intensity ratio are also detected, although the precise meaning of these observations is unclear

  13. QUANTITATIVE ANALYSIS OF RELATIONSHIP STRUCTURE AND ANIONIC SURFACTANT MICELLE CONCENTRATION CRITIC WITH SEMIEMPIRIS AM1

    Directory of Open Access Journals (Sweden)

    Eva Vaulina Yulistia Delsy

    2017-05-01

    Full Text Available This research determines the mathematical equation which calculate the Concentration Micelle Critic theoretical anionic surfactant. The research was conducted the depiction of each surfactant anionic three-dimensional compound models, followed by optimizing the model structure anionic surfactant by using AM1 calculation method. Furthermore the calculation of descriptors (QSPR method, then it was analyzed statistically using Multiple Linear Regression (MLR. The results of statistical calculations showed that to calculate the theoretical CMC anionic surfactant can use the QSPR equation: log CMC = 4.157+0.118qC1+7.698qC2+0.425α–0.010µ-0.129RD–0.138 log P+0.021BM–0.034Avdw, n = 100 ; r = 0.927 ; r2 = 0.860 ; SE = 0.352 ; F= 30.888 ; PRESS = 23.506

  14. Effect of surfactants on the properties of hydrotalcites prepared by the reverse micelle method

    Energy Technology Data Exchange (ETDEWEB)

    Holgado, Patricia H., E-mail: h.holgado@usal.es; Holgado, María J., E-mail: holgado@usal.es; San Román, María S., E-mail: sanroman@usal.es; Rives, Vicente, E-mail: vrives@usal.es

    2015-02-01

    Layered double hydroxides with the hydrotalcite-type structure have been prepared by the reverse micelles method. The layer cations were Ni{sup 2+} and Fe{sup 3+} in all cases and the interlayer anion was carbonate. We have studied the effect of the surfactant used (with linear chains of different lengths, or cyclic) and the effect of the pH on the properties of the solids formed. These have been characterized by element chemical analysis, powder X-ray diffraction, thermogravimetric analysis, temperature-programmed reduction, FT-IR and Vis–UV spectroscopies and scanning electron microscopy. It has been found that the samples prepared at pH 9 are more crystalline than those prepared at pH 11 and their crystallite sizes are always larger than for samples prepared by the conventional precipitation method. Surfactants with cyclic organic chains lead to a larger crystallite size, probably because the water pool vesicle where the crystallite grows is larger due to sterical hindrance of the organic chains. - Graphical abstract: Layered double hydroxides with the hydrotalcite-type structure with Ni{sup 2+} and Fe{sup 3+} cations in the layers have been prepared by the reverse micelles method. Different surfactants were used at different pH synthesis. Samples prepared at pH 9 are higher crystalline than those prepared at pH 11. Surfactants with cyclic organic chains lead to a larger crystallite size. - Highlights: • Hydrotalcites were prepared by the micelles reverse method. • Straight alkyl or cyclic chain surfactants were used. • All hydrotalcites are well crystallized at pH = 9 and 11. • The crystallite size depends on the linear/cyclic nature of the surfactant chain.

  15. Effect of surfactants on the properties of hydrotalcites prepared by the reverse micelle method

    International Nuclear Information System (INIS)

    Holgado, Patricia H.; Holgado, María J.; San Román, María S.; Rives, Vicente

    2015-01-01

    Layered double hydroxides with the hydrotalcite-type structure have been prepared by the reverse micelles method. The layer cations were Ni 2+ and Fe 3+ in all cases and the interlayer anion was carbonate. We have studied the effect of the surfactant used (with linear chains of different lengths, or cyclic) and the effect of the pH on the properties of the solids formed. These have been characterized by element chemical analysis, powder X-ray diffraction, thermogravimetric analysis, temperature-programmed reduction, FT-IR and Vis–UV spectroscopies and scanning electron microscopy. It has been found that the samples prepared at pH 9 are more crystalline than those prepared at pH 11 and their crystallite sizes are always larger than for samples prepared by the conventional precipitation method. Surfactants with cyclic organic chains lead to a larger crystallite size, probably because the water pool vesicle where the crystallite grows is larger due to sterical hindrance of the organic chains. - Graphical abstract: Layered double hydroxides with the hydrotalcite-type structure with Ni 2+ and Fe 3+ cations in the layers have been prepared by the reverse micelles method. Different surfactants were used at different pH synthesis. Samples prepared at pH 9 are higher crystalline than those prepared at pH 11. Surfactants with cyclic organic chains lead to a larger crystallite size. - Highlights: • Hydrotalcites were prepared by the micelles reverse method. • Straight alkyl or cyclic chain surfactants were used. • All hydrotalcites are well crystallized at pH = 9 and 11. • The crystallite size depends on the linear/cyclic nature of the surfactant chain

  16. Determination of the critical micelle concentration in simulations of surfactant systems

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Andrew P.; Panagiotopoulos, Athanassios Z., E-mail: azp@princeton.edu [Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    2016-01-28

    Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the “free” (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit)

  17. Determination of the critical micelle concentration in simulations of surfactant systems

    International Nuclear Information System (INIS)

    Santos, Andrew P.; Panagiotopoulos, Athanassios Z.

    2016-01-01

    Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the “free” (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit)

  18. SAXS and SANS studies of surfactants and reverse micelles in supercritical CO2

    International Nuclear Information System (INIS)

    Londono, J.D.; Dharmapurikar, R.S.; Wignall, G.D.; Cochran, H.D.

    1997-01-01

    Surfactants promise to extend the applicability of supercritical CO 2 (SC-CO 2 ) to processing of insoluble materials such as polymers and aqueous systems. In this short paper the authors summarize the techniques for studying surfactants and reverse micelles in SC-CO 2 using SAXS and SANS; they will describe the scattering instruments and the pressure cells for conducting these studies; they will describe the types of measurement that yield the desired characterizations; they will describe the methods of data analysis and interpretation; and they will provide illustrative results from this laboratory. Industry seeks to replace common organic solvents now used in many reaction and separation processes; SC-CO 2 is a potential solvent substitute widely favored by both government and industry. The currently available surfactants are limited in number and performance. In ongoing work the authors are coupling their SAXS and SANS scattering studies with complementary molecular simulations in efforts to understand, at a molecular level, what surfactant characteristics lead to improved performance. They hope that superior surfactants for use in SC-CO 2 can be designed and synthesized based on this new level of understanding

  19. Investigation of extractive microbial transformation in nonionic surfactant micelle aqueous solution using response surface methodology.

    Science.gov (United States)

    Xue, Yingying; Qian, Chen; Wang, Zhilong; Xu, Jian-He; Yang, Rude; Qi, Hanshi

    2010-01-01

    Extractive microbial transformation of L-phenylacetylcarbinol (L-PAC) in nonionic surfactant Triton X-100 micelle aqueous solution was investigated by response surface methodology. Based on the Box-Behnken design, a mathematical model was developed for the predication of mutual interactions between benzaldehyde, Triton X-100, and glucose on L-PAC production. It indicated that the negative or positive effect of nonionic surfactant strongly depended on the substrate concentration. The model predicted that the optimal concentration of benzaldehyde, Triton X-100, and glucose was 1.2 ml, 15 g, and 2.76 g per 100 ml, respectively. Under the optimal condition, the maximum L-PAC production was 27.6 mM, which was verified by a time course of extractive microbial transformation. A discrete fed-batch process for verification of cell activity was also presented.

  20. How Chain Length and Charge Affect Surfactant Denaturation of Acyl Coenzyme A Binding Protein (ACBP)

    DEFF Research Database (Denmark)

    Andersen, Kell Kleiner; Otzen, Daniel

    2009-01-01

    maltoside (DDM). The aim has been to determine how surfactant chain length and micellar charge affect the denaturation mechanism. ACBP denatures in two steps irrespective of surfactant chain length, but with increasing chain length, the potency of the denaturant rises more rapidly than the critical micelle......Using intrinsic tryptophan fluorescence, equilibria and kinetics of unfolding of acyl coenzyme A binding protein (ACBP) have been investigated in sodium alkyl sulfate surfactants of different chain length (8-16 carbon atoms) and with different proportions of the nonionic surfactant dodecyl...... constants increases linearly with denaturant concentration below the cmc but declines at higher concentrations. Both shortening chain length and decreasing micellar charge reduce the overall kinetics of unfolding and makes the dependence of unfolding rate constants on surfactant concentration more complex...

  1. Solubility enhancement of dioxins and PCBs by surfactant monomers and micelles quantified with polymer depletion techniques.

    Science.gov (United States)

    Schacht, Veronika J; Grant, Sharon C; Escher, Beate I; Hawker, Darryl W; Gaus, Caroline

    2016-06-01

    Partitioning of super-hydrophobic organic contaminants (SHOCs) to dissolved or colloidal materials such as surfactants can alter their behaviour by enhancing apparent aqueous solubility. Relevant partition constants are, however, challenging to quantify with reasonable accuracy. Partition constants to colloidal surfactants can be measured by introducing a polymer (PDMS) as third phase with known PDMS-water partition constant in combination with the mass balance approach. We quantified partition constants of PCBs and PCDDs (log KOW 5.8-8.3) between water and sodium dodecyl sulphate monomers (KMO) and micelles (KMI). A refined, recently introduced swelling-based polymer loading technique allowed highly precise (4.5-10% RSD) and fast (KMO. SHOC losses to experimental surfaces were substantial (8-26%) in monomer solutions, but had a low impact on KMO (0.10-0.16 log units). Log KMO for PCDDs (4.0-5.2) were approximately 2.6 log units lower than respective log KMI, which ranged from 5.2 to 7.0 for PCDDs and 6.6-7.5 for PCBs. The linear relationship between log KMI and log KOW was consistent with more polar and moderately hydrophobic compounds. Apparent solubility increased with increasing hydrophobicity and was highest in micelle solutions. However, this solubility enhancement was also considerable in monomer solutions, up to 200 times for OCDD. Given the pervasive presence of surfactant monomers in typical field scenarios, these data suggest that low surfactant concentrations may be effective long-term facilitators for subsurface transport of SHOCs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Extracting Aggregation Free Energies of Mixed Clusters from Simulations of Small Systems: Application to Ionic Surfactant Micelles.

    Science.gov (United States)

    Zhang, X; Patel, L A; Beckwith, O; Schneider, R; Weeden, C J; Kindt, J T

    2017-11-14

    Micelle cluster distributions from molecular dynamics simulations of a solvent-free coarse-grained model of sodium octyl sulfate (SOS) were analyzed using an improved method to extract equilibrium association constants from small-system simulations containing one or two micelle clusters at equilibrium with free surfactants and counterions. The statistical-thermodynamic and mathematical foundations of this partition-enabled analysis of cluster histograms (PEACH) approach are presented. A dramatic reduction in computational time for analysis was achieved through a strategy similar to the selector variable method to circumvent the need for exhaustive enumeration of the possible partitions of surfactants and counterions into clusters. Using statistics from a set of small-system (up to 60 SOS molecules) simulations as input, equilibrium association constants for micelle clusters were obtained as a function of both number of surfactants and number of associated counterions through a global fitting procedure. The resulting free energies were able to accurately predict micelle size and charge distributions in a large (560 molecule) system. The evolution of micelle size and charge with SOS concentration as predicted by the PEACH-derived free energies and by a phenomenological four-parameter model fit, along with the sensitivity of these predictions to variations in cluster definitions, are analyzed and discussed.

  3. The structure of normal ionic micelles by interpretation of small-angle neutron scattering data from selectively labeled (2H, 19F) surfactant solutions

    International Nuclear Information System (INIS)

    Berr, S.S.

    1986-12-01

    We have determined the structure of micelles formed in water by several classes of ionic surfactants under a variety of experimental conditions using small-angle neutron scattering (SANS) techniques. Contrast between the micelles and the solvent was achieved through either selective deuteration or fluorination of the surfactant, or through the use of D 2 O. Interpretation of SANS data was facilitated by the use of Hayter, Penfold, and Hansen's rescaled Mean Spherical Approximation theory to calculate the scattering due to interparticle interactions. We have devised a number of micelle models, both spherical and ellipsoidal, to account for the scattering due to single micelles. It was found that changing the solvent from H 2 O to D 2 O results in the formation of larger micelles due to changes in the solvent-surfactant hydrocarbon interactions. This solvent isotope effect increased as the length of the alkyl chain increased. The fractional micellar charge did not change with respect to isotopic composition of solvent. We found that alkyltrimethylammonium bromide surfactants form drier micelles than do the sodium alkyl sulfate surfactants of equal chain length. Also, all micelles studied were found to be dry near the critical micelle concentration (cmc) and to become increasingly wetter as the concentration increased. The increase in aggregation number with respect to the square root of surfactant concentration was found to be linear for all systems studied. 80 figs

  4. Mixed micelles of polyethylene glycol (23) lauryl ether with ionic surfactants studied by proton 1D and 2D NMR.

    Science.gov (United States)

    Gao, Hong-Chang; Zhao, Sui; Mao, Shi-Zhen; Yuan, Han-Zhen; Yu, Jia-Yong; Shen, Lian-Fang; Du, You-Ru

    2002-05-01

    (1)H NMR chemical shift, spin-lattice relaxation time, spin-spin relaxation time, self-diffusion coefficient, and two-dimensional nuclear Overhauser enhancement (2D NOESY) measurements have been used to study the nonionic-ionic surfactant mixed micelles. Cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) were used as the ionic surfactants and polyethylene glycol (23) lauryl ether (Brij-35) as the nonionic surfactant. The two systems are both with varying molar ratios of CTAB/Brij-35 (C/B) and SDS/Brij-35 (S/B) ranging from 0.5 to 2, respectively, at a constant concentration of 6 mM for Brij-35 in aqueous solutions. Results give information about the relative arrangement of the surfactant molecules in the mixed micelles. In the former system, the trimethyl groups attached to the polar heads of the CTAB molecules are located between the first oxy-ethylene groups next to the hydrophobic chains of Brij-35 molecules. These oxy-ethylene groups gradually move outward from the hydrophobic core of the mixed micelle with an increase in C/B in the mixed solution. In contrast to the case of the CTAB/Triton X-100 system, the long flexible hydrophilic poly oxy-ethylene chains, which are in the exterior part of the mixed micelles, remain coiled, but looser, surrounding the hydrophobic core. There is almost no variation in conformation of the hydrophilic chains of Brij-35 molecules in the mixed micelles of the SDS/Brij-35 system as the S/B increases. The hydrophobic chains of both CTAB and SDS are co-aggregated with Brij-35, respectively, in their mixed micellar cores.

  5. Mixed Micelle System Produced by Interaction Between Transglycosylated Stevia and an Ionic Surfactant Improves Dissolution Profile of Mefenamic Acid.

    Science.gov (United States)

    Fujimori, Miki; Kadota, Kazunori; Tozuka, Yuichi

    2017-04-01

    Transglycosylated stevia (stevia-G) can effectively improve the dissolution and bioavailability of poorly water-soluble drugs. Furthermore, addition of an ionic surfactant to stevia-G solution has been shown to enhance the dissolution effect of stevia-G on flurbiprofen. Herein, 4 surfactants, namely sodium dodecyl sulfate, sodium N-dodecanoylsarcosinate, sodium monododecyl phosphate, and lauryltrimethylammonium chloride (LTAC) were screened to investigate their synergistic effect with stevia-G in enhancing the solubility of mefenamic acid (MFA). The ternary formulation containing LTAC produced the highest increase in solubility, whereas the binary MFA/LTAC formulation did not increase the solubility of MFA. Surface tension was evaluated to analyze the interaction between stevia-G and each ionic surfactant, wherein the Rubingh model was applied to predict mixed micelle formation between stevia-G and LTAC. Interaction parameters calculated by the Rubingh model reflected mixed micelle formation between stevia-G and LTAC relative to the self-interactions of the 2 individual surfactants. All interaction parameters in this system showed negative values, indicating a favorable interaction (e.g., hydrogen bond or electrostatic and dipole) between binary components in the mixed micelles. Spray-dried particles of ternary formulations (MFA/stevia-G/LTAC) were prepared to evaluate the dissolution profile and physicochemical properties. Dissolution profiling showed that the concentration of MFA released from spray-dried particles was significantly higher than untreated MFA. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  6. Critical micelle concentration of surfactants in aqueous buffered and unbuffered systems

    International Nuclear Information System (INIS)

    Fuguet, Elisabet; Rafols, Clara; Roses, Marti; Bosch, Elisabeth

    2005-01-01

    Critical micelle concentration (CMC) of sodium dodecyl sulphate (SDS), lithium perfluorooctanesulfonate (LPFOS), hexadecyltrimethylammonium bromide (HTAB), tetradecyltrimethylammonium bromide (TTAB), and sodium cholate (SC), surfactants commonly used as pseudostationary phases in micellar electrokinetic chromatography (MEKC), have been determined by means of three different methods: MEKC, spectrophotometry, and conductometry. Determinations have been performed in water, and also in different concentrations of phosphate buffer at pH 7.0. CMC values ranging from 8.08 (water) to 1.99 (50 mM phosphate buffer) mM for SDS, from 7.16 (water) to 2,81 (30 mM phosphate buffer) mM for LPFOS, from 3.77 (water) to 1.93 (20 mM phosphate buffer) mM for TTAB, from 0.91 (water) to ∼0.34 (20 mM phosphate buffer) for HTAB, and around 13 mM (20 mM phosphate buffer) for SC, are obtained. The effect of the electrolyte concentration on the CMC, as well as the linear relationship between the electrolyte counter-ion concentration and the CMC are discussed. This linear relationship provides an easy way for users to estimate the CMC of a MEKC system, at a given electrolyte concentration. A comparison between experimental methods, as well as a discussion about the suitability of a given method for the determination of the CMC for a given surfactant system is also provided

  7. Novel sample preparation method for surfactant containing suppositories: effect of micelle formation on drug recovery.

    Science.gov (United States)

    Kalmár, Éva; Ueno, Konomi; Forgó, Péter; Szakonyi, Gerda; Dombi, György

    2013-09-01

    Rectal drug delivery is currently at the focus of attention. Surfactants promote drug release from the suppository bases and enhance the formulation properties. The aim of our work was to develop a sample preparation method for HPLC analysis for a suppository base containing 95% hard fat, 2.5% Tween 20 and 2.5% Tween 60. A conventional sample preparation method did not provide successful results as the recovery of the drug failed to fulfil the validation criterion 95-105%. This was caused by the non-ionic surfactants in the suppository base incorporating some of the drug, preventing its release. As guidance for the formulation from an analytical aspect, we suggest a well defined surfactant content based on the turbidimetric determination of the CMC (critical micelle formation concentration) in the applied methanol-water solvent. Our CMC data correlate well with the results of previous studies. As regards the sample preparation procedure, a study was performed of the effects of ionic strength and pH on the drug recovery with the avoidance of degradation of the drug during the procedure. Aminophenazone and paracetamol were used as model drugs. The optimum conditions for drug release from the molten suppository base were found to be 100 mM NaCl, 20-40 mM NaOH and a 30 min ultrasonic treatment of the final sample solution. As these conditions could cause the degradation of the drugs in the solution, this was followed by NMR spectroscopy, and the results indicated that degradation did not take place. The determined CMCs were 0.08 mM for Tween 20, 0.06 mM for Tween 60 and 0.04 mM for a combined Tween 20, Tween 60 system. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Sugar-based gemini surfactant with a vesicle-to-micelle transition at acidic pH and a reversible vesicle flocculation near neutral pH

    NARCIS (Netherlands)

    Johnsson, M; Wagenaar, A; Engberts, JBFN

    2003-01-01

    A sugar-based (reduced glucose) gemini surfactant forms vesicles in dilute aqueous solution near neutral pH. At lower pH, there is a vesicle-to-micelle transition within a narrow pH region (pH 6.0-5.6). The vesicles are transformed into large cylindrical micelles that in turn are transformed into

  9. Effect of counterions on properties of micelles formed by alkylpyridinium surfactants .1. Conductometry and H-1-NMR chemical shifts

    OpenAIRE

    Bijma, K; Engberts, J.B.F.N.

    1997-01-01

    This paper delineates the influence of counterions on the aggregation behavior of 1-methyl-4-n-dodecylpyridinium surfactants, using conductometry and H-1-NMR spectroscopy. Three types of counterions have been studied: (i) halides, (ii) alkanesulfonates, and (iii) aromatic counterions. The critical. micelle concentration is found to decrease with increasing counterion size and increasing counterion hydrophobicity, whereas the degree of counterion binding increases. The aggregation behavior of ...

  10. Modeling of the Critical Micelle Concentration (CMC) of Nonionic Surfactants with an Extended Group-Contribution Method

    DEFF Research Database (Denmark)

    Mattei, Michele; Kontogeorgis, Georgios; Gani, Rafiqul

    2013-01-01

    , those compounds that exhibit larger correlation errors (based only on first- and second-order groups) are assigned to more detailed molecular descriptions, so that better correlations of critical micelle concentrations are obtained. The group parameter estimation has been performed using a data set......A group-contribution (GC) property prediction model for estimating the critical micelle concentration (CMC) of nonionic surfactants in water at 25 °C is presented. The model is based on the Marrero and Gani GC method. A systematic analysis of the model performance against experimental data...... concentration, and in particular, the quantitative structure−property relationship models, the developed GC model provides an accurate correlation and allows for an easier and faster application in computer-aided molecular design techniques facilitating chemical process and product design....

  11. Determination of the Critical Micelle Concentration of Neutral and Ionic Surfactants with Fluorometry, Conductometry, and Surface Tension-A Method Comparison.

    Science.gov (United States)

    Scholz, Norman; Behnke, Thomas; Resch-Genger, Ute

    2018-01-01

    Micelles are of increasing importance as versatile carriers for hydrophobic substances and nanoprobes for a wide range of pharmaceutical, diagnostic, medical, and therapeutic applications. A key parameter indicating the formation and stability of micelles is the critical micelle concentration (CMC). In this respect, we determined the CMC of common anionic, cationic, and non-ionic surfactants fluorometrically using different fluorescent probes and fluorescence parameters for signal detection and compared the results with conductometric and surface tension measurements. Based upon these results, requirements, advantages, and pitfalls of each method are discussed. Our study underlines the versatility of fluorometric methods that do not impose specific requirements on surfactants and are especially suited for the quantification of very low CMC values. Conductivity and surface tension measurements yield smaller uncertainties particularly for high CMC values, yet are more time- and substance consuming and not suitable for every surfactant.

  12. Kolliphor surfactants affect solubilization and bioavailability of fenofibrate. Studies of in vitro digestion and absorption in rats

    DEFF Research Database (Denmark)

    Berthelsen, Ragna; Holm, Rene; Jacobsen, Jette

    2015-01-01

    formulations only comprised an aqueous micellar solution of the model drug (fenofibrate) in varying concentrations (2–25% (w/v)) of the three tested surfactants. Increased concentrations of Kolliphor ELP and EL led to increased fenofibrate AUC0–24h values. For the Kolliphor RH40 formulations, an apparent...... fenofibrate absorption optimum was seen at 15% (w/v) surfactant, displaying both the highest AUC0–24h and Cmax. The reduced absorption of fenofibrate from the formulation containing the highest level of surfactant (25% w/v) was thought to be caused by some degree of trapping within Kolliphor RH40 micelles....... In vitro, Kolliphor ELP and EL were found to be more prone to digestion than Kolliphor RH40, though not affecting the in vivo results. The highest fenofibrate bioavailability was attained from formulations with high Kolliphor ELP/EL levels (25% (w/v)), indicating that these surfactants are the better...

  13. Indication of critical micelle concentration of nonionic surfactants with large emission change using water-soluble conjugated polymer as molecular light switch

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Lilin, E-mail: sunlilin126@126.com [Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Hao, Dan; Zhang, Ping; Qian, Zhangsheng; Shen, Weili [Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Shao, Taili [Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Department of Pharmacy, Wannan Medical College, Wuhu 241000 (China); Zhu, Changqing, E-mail: zhucq@mail.ahnu.edu.cn [Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China)

    2013-02-15

    A new near-infrared water-soluble conjugated polymer, i.e. poly [2,5-di (propyloxysulfonate)-1,4-phenylene-ethynylene-9,10-anthrylene] (PPEASO3) was synthesized to investigate its interaction with surfactants. It was found that PPEASO3 has only a weak fluorescence emission at about 670 nm due to its self-aggregation in water and in aqueous solution containing a low concentration of nonionic surfactants, i.e. below their critical micelle concentration (CMC). However, a dramatic fluorescence enhancement with a large emission blue-shift (>40 nm) was found once the concentration of nonionic surfactants reached the CMC (especially for Triton X-100). An orange fluorescence could be observed even with naked-eyes under UV-lamp, which gave a direct indication for the micelle forming process and provided a simple method for the CMC determination of the nonionic surfactants. The CMC values determined by this method were in good agreement with those obtained by other techniques. The dramatic emission change observed could be ascribed to the intensive hydrophobic interaction between PPEASO3 and surfactants micelle, which greatly disrupts the aggregation of the polymer and increase the fluorescence efficiency of PPEASO3. Highlights: Black-Right-Pointing-Pointer Investigated the interaction of a new water-soluble conjugated polymer with surfactants. Black-Right-Pointing-Pointer The dramatic fluorescence enhancement and emission blue-shift were observed at the CMC. Black-Right-Pointing-Pointer The obvious emission color change could be observed with naked-eyes under UV-lamp. Black-Right-Pointing-Pointer Gave a direct indication for the micelle forming process. Black-Right-Pointing-Pointer Provided a simple method for the CMC determination of the nonionic surfactants.

  14. Switching wormlike micelles of selenium-containing surfactant using redox reaction.

    Science.gov (United States)

    Zhang, Yongmin; Kong, Weiwei; Wang, Cheng; An, Pengyun; Fang, Yun; Feng, Yujun; Qin, Zhirong; Liu, Xuefeng

    2015-10-14

    A novel redox-switchable wormlike micellar system was developed based on a mixture of selenium-containing zwitterionic surfactant and commercially available anionic surfactant sodium dodecyl sulfate, which reversibly and quickly responds to H2O2 and vitamin C, and shows circulatory gel/sol transition, reflecting changes in aggregate morphology from entangled worms to vesicles.

  15. Conductometric study of sodium dodecyl sulfate - nonionic surfactant (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85 mixed micelles in aqueous solution

    Directory of Open Access Journals (Sweden)

    Ćirin Dejan M.

    2012-01-01

    Full Text Available The present study is concerned with the determination of the critical micelle concentration (cmc of mixed micelles of sodium dodecyl sulfate with one of five nonionic surfactants (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85 from conductance measurements. Based on the calculated values of the β parameters we have noticed that SDS-nonionic surfactants mostly showed strong synergistic effect. It was found that nonionic surfactants with mainly longer and more hydrophobic tail show stronger interactions with hydrophobic part of SDS, thus expressing stronger synergism. In SDS-Tween 80 binary system the strongest synergistic effect was noticed. SDS-Tween 85 micellar system showed antagonistic effect, most probably because the presence of the double bond in its three hydrophobic tails (three C18 tails makes it sterically rigid.

  16. Supramolecular "Big Bang" in a Single-Ionic Surfactant/Water System Driven by Electrostatic Repulsion: From Vesicles to Micelles.

    Science.gov (United States)

    Leclercq, Loïc; Bauduin, Pierre; Nardello-Rataj, Véronique

    2017-04-11

    In aqueous solution, dimethyldi-n-octylammonium chloride, [DiC 8 ][Cl], spontaneously forms dimers at low concentrations (1-10 mM) to decrease the strength of the hydrophobic-water contact. Dimers represent ideal building blocks for the abrupt edification of vesicles at 10 mM. These vesicles are fully characterized by dynamic and static light scattering, self-diffusion nuclear magnetic resonance, and freeze-fracture transmission electron microscopy. An increase in concentration leads to electrostatic repulsion between vesicles that explode into small micelles at 30 mM. These transitions are detected by means of surface tension, conductivity, and solubility of hydrophobic solutes as well as by isothermal titration microcalorimetry. These unusual supramolecular transitions emerge from the surfactant chemical structure that combines two contradictory features: (i) the double-chain structure tending to form low planar aggregates with low water solubility and (ii) the relatively short chains giving high hydrophilicity. The well-balanced hydrophilic-hydrophobic character of [DiC 8 ][Cl] is then believed to be at the origin of the unusual supramolecular sequence offering new opportunities for drug delivery systems.

  17. Revealing New Structural Insights from Surfactant Micelles through DLS, Microrheology and Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Samiul Amin

    2015-06-01

    Full Text Available The correlation between molecular changes and microstructural evolution of rheological properties has been demonstrated for the first time in a mixed anionic/zwitterionic surfactant-based wormlike micellar system. Utilizing a novel combination of DLS-microrheology and Raman Spectroscopy, the effect of electrostatic screening on these properties of anionic (SLES and zwitterionic (CapB surfactant mixtures was studied by modulating the NaCl concentration. As Raman Spectroscopy delivers information about the molecular structure and DLS-microrheology characterizes viscoelastic properties, the combination of data delivered allows for a deeper understanding of the molecular changes underlying the viscoelastic ones. The high frequency viscoelastic response obtained through DLS-microrheology has shown the persistence of the Maxwell fluid response for low viscosity solutions at high NaCl concentrations. The intensity of the Raman band at 170 cm−1 exhibits very strong correlation with the viscosity variation. As this Raman band is assigned to hydrogen bonding, its variation with NaCl concentration additionally indicates differences in water structuring due to potential microstructural differences at low and high NaCl concentrations. The microstructural differences at low and high NaCl concentrations are further corroborated by persistence of a slow mode at the higher NaCl concentrations as seen through DLS measurements. The study illustrates the utility of the combined DLS, DLS-optical microrheology and Raman Spectroscopy in providing new molecular structural insights into the self-assembly process in complex fluids.

  18. Viscoelastic wormlike micelles formed by ionic liquid-type surfactant [C16imC8]Br towards template-assisted synthesis of CdS quantum dots.

    Science.gov (United States)

    Hu, Yimin; Han, Jie; Ge, Lingling; Guo, Rong

    2018-01-31

    In this paper, viscoelastic wormlike micelles consisting of cationic liquid-type surfactant, 1-hexadecyl-3-octyl imidazolium bromide ([C 16 imC 8 ]Br), water and different additives were utilized for the synthesis of CdS quantum dots. First, the influence of different additives, such as [Cd(NH 3 ) 6 ]Cl 2 and ethanethioamid (precursors for the synthesis of CdS quantum dots), and temperature on the viscoelasticity of the [C 16 imC 8 ]Br aqueous solution was studied by dynamic and steady rheology. Furthermore, the synthesized CdS quantum dots and their photoluminescence properties were characterized by transmission electron microscopy (TEM), UV-Vis absorption spectroscopy, X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX). In the end, the mechanism for the synthesis of CdS quantum dots in [C 16 imC 8 ]Br wormlike micelles is proposed.

  19. Calculations of critical micelle concentration by dissipative particle dynamics simulations: the role of chain rigidity.

    Science.gov (United States)

    Lee, Ming-Tsung; Vishnyakov, Aleksey; Neimark, Alexander V

    2013-09-05

    Micelle formation in surfactant solutions is a self-assembly process governed by complex interplay of solvent-mediated interactions between hydrophilic and hydrophobic groups, which are commonly called heads and tails. However, the head-tail repulsion is not the only factor affecting the micelle formation. For the first time, we present a systematic study of the effect of chain rigidity on critical micelle concentration and micelle size, which is performed with the dissipative particle dynamics simulation method. Rigidity of the coarse-grained surfactant molecule was controlled by the harmonic bonds set between the second-neighbor beads. Compared to flexible molecules with the nearest-neighbor bonds being the only type of bonded interactions, rigid molecules exhibited a lower critical micelle concentration and formed larger and better-defined micelles. By varying the strength of head-tail repulsion and the chain rigidity, we constructed two-dimensional diagrams presenting how the critical micelle concentration and aggregation number depend on these parameters. We found that the solutions of flexible and rigid molecules that exhibited approximately the same critical micelle concentration could differ substantially in the micelle size and shape depending on the chain rigidity. With the increase of surfactant concentration, primary micelles of more rigid molecules were found less keen to agglomeration and formation of nonspherical aggregates characteristic of flexible molecules.

  20. Adsorption properties of biologically active derivatives of quaternary ammonium surfactants and their mixtures at aqueous/air interface II. Dynamics of adsorption, micelles dissociation and cytotoxicity of QDLS.

    Science.gov (United States)

    Rojewska, Monika; Prochaska, Krystyna; Olejnik, Anna; Rychlik, Joanna

    2014-07-01

    The main aim of our study was analysis of adsorption dynamics of mixtures containing quaternary derivatives of lysosomotropic substance (QDLS). Two types of equimolar mixtures were considered: the ones containing two derivatives of lysosomotropic substances (DMALM-12 and DMGM-12) as well as the catanionic mixtures i.e. the systems containing QDLS and DBSNa. Dynamic surface tension measurements of surfactant mixtures were made. The results suggested that the diffusivity of the mixed system could be treated as the average value of rates of diffusion of individual components, micelles and ion pairs, which are present in the mixtures studied. Moreover, an attempt was made to explain the influence of the presence of micelles in the mixtures on their adsorption dynamics. The compounds examined show interesting biological properties which can be useful, especially for drug delivery in medical treatment. In vitro cytotoxic activities of the mixtures studied towards human cancer cells were evaluated. Most of the mixtures showed a high antiproliferative potential, especially the ones containing DMALM-12. Each cancer cell line used demonstrated different sensitivity to the same dose of the mixtures tested. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Unusual nanosized associates of carboxy-calix[4]resorcinarene and cetylpyridinium chloride: the macrocycle as a glue for surfactant micelles.

    Science.gov (United States)

    Morozova, Ju E; Syakaev, V V; Shalaeva, Ya V; Ermakova, A M; Nizameev, I R; Kadirov, M K; Voloshina, A D; Zobov, V V; Antipin, I S; Konovalov, A I

    2017-03-08

    The association of cetylpyridinium chloride (CPC) micelles in the presence of octaacetated tetraphenyleneoxymethylcalix[4]resorcinarene (CR) leads to the formation of unusual spherical supramolecular nanoparticles (SNPs). Within the range of CR/CPC molar ratios from 10/1 to 1/10 (except for 1/8), CR, acting as a counterion, decreases the critical micelle concentration of CPC by one order of magnitude and leads to the formation of SNPs with an average hydrodynamic radius of 164 nm and an average zeta potential of -60 mV. The formation of SNPs was studied by NMR FT-PGSE and 2D NOESY, DLS, TEM, fluorimetry, and UV-Vis methods. The stability of SNPs at different temperatures and pH values and in the presence of electrolytes was investigated. The specificity of the interactions of the SNPs with substrates that were preferentially bound by a macrocycle or CPC micelle was studied. The enhancement of cation dye binding in the presence of SNPs is shown. The presented supramolecular system may serve as a nanocapsule for water-soluble and water-insoluble compounds.

  2. Factors affecting responses of infants with respiratory distress syndrome to exogenous surfactant therapy.

    Science.gov (United States)

    Ho, N K

    1993-02-01

    Approximately 20% to 30% of infants with respiratory distress syndrome (RDS) do not respond to surfactant replacement therapy. Unfortunately there is no uniform definition of 'response' or 'non-response' to surfactant therapy. Response was based on improvement in a/A PO2 and/or mean airway pressure (MAP) by some and on improvement in FIO2 and/or MAP by others. Even the point of time at which evaluation of response was done is different in various reports. There is an urgent need to adopt an uniform definition. Most premature babies are surfactant deficient which is the aetiological factor of RDS. Generally good antenatal care and perinatal management are essential in avoidance of premature birth. Babies with lung hypoplasia and who are extremely premature (less than 24 weeks of gestation) do not respond well to exogenous surfactant replacement because of structural immaturity. Prompt management of asphyxiated birth and shock are necessary as there may be negative response to surfactant replacement. Foetal exposure to glucocorticoids improves responsiveness to postnatal administration of surfactant. Antenatal steroid therapy has become an important part of management of RDS with surfactant replacement. The premature lungs with high alveolar permeability tend to develop pulmonary oedema. With the presence of plasma-derived surfactant inhibitors, the response to exogenous surfactant may be affected. These inhibitors may also be released following ventilator barotrauma. The standard of neonatal intensive care such as ventilatory techniques has an important bearing on the outcome of the RDS babies.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Effect of counterions on properties of micelles formed by alkylpyridinium surfactants .1. Conductometry and H-1-NMR chemical shifts

    NARCIS (Netherlands)

    Bijma, K; Engberts, J.B.F.N.

    1997-01-01

    This paper delineates the influence of counterions on the aggregation behavior of 1-methyl-4-n-dodecylpyridinium surfactants, using conductometry and H-1-NMR spectroscopy. Three types of counterions have been studied: (i) halides, (ii) alkanesulfonates, and (iii) aromatic counterions. The critical.

  4. Photophysical properties of pyronin dyes in reverse micelles of AOT

    Energy Technology Data Exchange (ETDEWEB)

    Bayraktutan, Tuğba; Meral, Kadem; Onganer, Yavuz, E-mail: yonganer@atauni.edu.tr

    2014-01-15

    The photophysical properties of pyronin B (PyB) and pyronin Y (PyY) in reverse micelles formed with water/sodium bis (2-ethyl-1-hexyl) sulfosuccinate (AOT)/n-heptane were investigated by UV–vis absorption, steady-state and time-resolved fluorescence spectroscopy techniques. This study was carried out a wide range of reverse micelle sizes, with hydrodynamic radii ranging from 1.85 to 9.38 nm. Significant photophysical parameters as band shifts, fluorescence quantum yields and fluorescence lifetimes were determined to understand how photophysical and spectroscopic features of the dye compounds were affected by the variation of reverse micelle sizes. In this regard, control of reverse micelle size by changing W{sub 0}, the molar ratio of water to surfactant, allowed tuning the photophysical properties of the dyes in organic solvent via reverse micelle. Non-fluorescent H-aggregates of pyronin dyes were observed for the smaller reverse micelles whereas an increase in the reverse micelle size induced an increment in the amount of dye monomers instead of dye aggregates. Thus, the fluorescence intensities of the dyes were improved by increasing W{sub 0} due to the predomination of the fluorescent dye monomers. As a result, the fluorescence quantum yields also increased. The fluorescence lifetimes of the dyes in the reverse micelles were determined by the time-resolved fluorescence decay studies. Evaluation of the fluorescence lifetimes calculated for pyronin dyes in the reverse micelles showed that the size of reverse micelle affected the fluorescence lifetimes of pyronin dyes. -- Highlights: • The photophysical properties of pyronin dyes were examined by spectroscopic techniques. • Optical properties of the dyes were tuned by changing of W{sub 0} values. • The fluorescence lifetime and quantum yield values of the dyes in reverse micelles were discussed.

  5. Factors affecting the stability of drug-loaded polymeric micelles and strategies for improvement

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Weisai; Li, Caibin; Wang, Zhiyu; Zhang, Wenli, E-mail: zwllz@163.com; Liu, Jianping, E-mail: liujianpingljp@hotmail.com [China Pharmaceutical University, Department of Pharmaceutics (China)

    2016-09-15

    Polymeric micelles (PMs) self-assembled by amphiphilic block copolymers have been used as promising nanocarriers for tumor-targeted delivery due to their favorable properties, such as excellent biocompatibility, prolonged circulation time, favorable particle sizes (10–100 nm) to utilize enhanced permeability and retention effect and the possibility for functionalization. However, PMs can be easily destroyed due to dilution of body fluid and the absorption of proteins in system circulation, which may induce drug leakage from these micelles before reaching the target sites and compromise the therapeutic effect. This paper reviewed the factors that influence stability of micelles in terms of thermodynamics and kinetics consist of the critical micelle concentration of block copolymers, glass transition temperature of hydrophobic segments and polymer–polymer and polymer–cargo interaction. In addition, some effective strategies to improve the stability of micelles were also summarized.Graphical Abstract.

  6. Supercritical fluid reverse micelle separation

    Science.gov (United States)

    Fulton, J.L.; Smith, R.D.

    1993-11-30

    A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W[sub o] that determines the maximum size of the reverse micelles. The maximum ratio W[sub o] of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions. 27 figures.

  7. Solvation dynamics in triton-X-100 and triton-X-165 micelles: Effect of micellar size and hydration

    Science.gov (United States)

    Kumbhakar, Manoj; Nath, Sukhendu; Mukherjee, Tulsi; Pal, Haridas

    2004-09-01

    Dynamic Stokes' shift measurements using coumarin 153 as the fluorescence probe have been carried out to study solvation dynamics in two nonionic micelles, viz., triton-X-100 (TX-100) and triton-X-165 (TX-165). In both the micelles, the solvent relaxation dynamics is biexponential in nature. While the fast solvation time τs1 is seen to be almost similar for both the micelles, the slow solvation time τs2 is found to be appreciably smaller in TX-165 than in TX-100 micelle. Dynamic light scattering measurements indicate that the TX-165 micelles are substantially smaller in size than that of TX-100. Assuming similar core size for both the micelles, as expected from the similar chemical structures of the nonpolar ends for both the surfactants, the Palisade layer is also indicated to be substantially thinner for TX-165 micelles than that of TX-100. The aggregation number of TX-165 micelles is also found to be substantially smaller than that of TX-100 micelles. Fluorescence spectral studies of C153 dye in the two micelles indicate that the Palisade layer of TX-165 micelles is more polar than that of TX-100 micelles. Fluorescence anisotropy measurements indicate that the microviscosity in the Palisade layer of TX-165 micelles is also lower than that of TX-100 micelles. Based on these results it is inferred that the structure of the Palisade layer of TX-165 micelles is quite loose and have higher degree hydration in comparison to that of TX-100 micelles. Due to these structural differences in the Palisade layers of TX-165 and TX-100 micelles the solvation dynamics is faster in the former micelles than in the latter. It has been further inferred that in the present systems the collective response of the water molecules at somewhat away from the probes is responsible for the faster component of the solvation time, which does not reflect much of the structural changes of the micellar Palisade layer. On the contrary, the slower solvation time component, which is mainly due to

  8. EPR spin probe and spin label studies of some low molecular and polymer micelles

    Science.gov (United States)

    Wasserman, A. M.; Kasaikin, V. A.; Timofeev, V. P.

    1998-12-01

    The rotational mobility of spin probes of different shape and size in low molecular and polymer micelles has been studied. Several probes having nitroxide fragment localized either in the vicinity of micelle interface or in the hydrocarbon core have been used. Upon increasing the number of carbon atoms in hydrocarbon chain of detergent from 7 to 13 (sodium alkyl sulfate micelles) or from 12 to 16 (alkyltrimethylammonium bromide micelles) the rotational mobility of spin probes is decreased by the factor 1.5-2.0. The spin probe rotational mobility in polymer micelles (the complexes of alkyltrimethylammonium bromides and polymethacrylic or polyacrylic acids) is less than mobility in free micelles of the same surfactants. The study of EPR-spectra of spin labeled polymethacrylic acid (PMA) indicated that formation of water soluble complexes of polymer and alkyltrimethylammonium bromides in alkaline solutions (pH 9) does not affect the polymer segmental mobility. On the other hand, the polymer complexes formation in slightly acidic water solution (pH 6) breaks down the compact PMA conformation, thus increasing the polymer segmental mobility. Possible structures of polymer micelles are discussed.

  9. Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

    Science.gov (United States)

    Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy inputenables the precise contr...

  10. Gemini (dimeric) Surfactants

    Indian Academy of Sciences (India)

    is in turn bonded to an identical hydrocarbon tail; alternatively,. ~. Tail spacer ... formed is dependent on surfactant structure, temperature, ionic strength and pH. The models of GS are .... micelle to the air/water interface. Moreover, GS can be ...

  11. Molecular interactions in a surfactant-water-polyacrylamide system, according to densimetry, viscometry, conductometry, and spectroscopy data

    Science.gov (United States)

    Harutyunyan, R. S.

    2013-08-01

    Molecular interactions in a surfactant-polyacrylamide-water system are investigated. It is established that the interactions affect such physicochemical parameters of the system as viscosity, density, surface tension, conductivity, and critical micelle concentration. It is shown that in a polyacrylamide-water system, raising the polyacrylamide concentration to 0.02% causes conformational changes in its macromolecule.

  12. Small angle neutron scattering study of doxorubicin–surfactant ...

    Indian Academy of Sciences (India)

    The binding affinity of doxorubicin within the micelle carrier is enhanced through complex formation of drug and anionic surfactant, aerosol OT (AOT). Electrostatic binding of doxorubicin with negatively charged surfactants leads to the formation of hydrophobic drug–surfactant complexes. Surfactant-induced partitioning of ...

  13. Temperature-dependent magnetic field effect study on exciplex luminescence: probing the triton X-100 reverse micelle in cyclohexane.

    Science.gov (United States)

    Das, Doyel; Nath, Deb Narayan

    2007-09-20

    The microenvironment within the reverse micelle of the nonionic surfactant Triton X-100 (TX-100) in cyclohexane has been investigated by studying the magnetic field effect (MFE) on pyrene-dimethylaniline exciplex luminescence. The nature of exciplex fluorescence and its behavior in the presence of a magnetic field have been found to vary significantly with the water content of the medium. Results are discussed in light of multiple exciplex formation within the micelle which is further supported by the fluorescence lifetime measurements. Those exciplexes emitting at longer wavelength are found to be magnetic field sensitive while those emitting toward the blue region of the spectrum are insensitive toward magnetic field. Since the exciplex's emission characteristics and magnetic field sensitivity depend on its immediate surrounding, it has been concluded that the environment within the micelle is nonuniform. With an increase in hydration level, different zones of varying polarity are created within the reverse micelle. It has been pointed out that the magnetic field sensitive components reside inside the polar core of the micelle while those located near the hydrocarbon tail are field insensitive. However it has been presumed that an interconversion between the different types of exciplexes is possible. The environment within the reverse micelle is found to be largely affected by the change in temperature, and this is reflected in the exciplex emission property and the extent of magnetic field effect. Interestingly, the variation of MFE with temperature follows different trends in the dry and the wet reverse micelle. A comparison has been drawn with the reverse micelle of the ionic surfactant to get an insight into the difference between the various types of micellar environment.

  14. Use of functionalized surfactants in flame atomic analysis: Final technical report

    International Nuclear Information System (INIS)

    Armstrong, D.W.

    1987-01-01

    Research results in the following areas are briefly summarized: basic properties of surfactants, micelles, and cyclodextrins as they relate to chemical analysis; use of functionalized surfactants, micelles, and cyclodextrins in spectroscopic analysis; macromolecular separation theory and mechanism; use of functionalized surfactants and cyclodextrins in separations; capillary work for future coupling of spectroscopic and LC projects

  15. Micelle fission through surface instability and formation of an interdigitating stalk

    NARCIS (Netherlands)

    Sammalkorpi, M.; Karttunen, M.E.J.; Haataja, M.

    2008-01-01

    We report on the first detailed atomic-scale studies of micelle fission in micellar systems consisting of anionic sodium dodecyl sulfate with explicit solvent. We demonstrate a new micelle fission pathway for ionic surfactants and show how micelle fission can be induced by varying the ionic

  16. Surfactant-aided size exclusion chromatography

    NARCIS (Netherlands)

    Horneman, D.A.; Wolbers, M.; Zomerdijk, M.; Ottens, M.; Keurentjes, J.T.F.; Wielen, van der L.A.M.

    2004-01-01

    The flexibility and selectivity of size exclusion chromatog. (SEC) for protein purifn. can be modified by adding non-ionic micelle-forming surfactants to the mobile phase. The micelles exclude proteins from a liq. phase similar to the exclusion effect of the polymer fibers of the size exclusion

  17. Smart wormlike micelles design, characteristics and applications

    CERN Document Server

    Feng, Yujun; Dreiss, Cécile A

    2015-01-01

    This Brief provides an up-to-date overview of smart surfactants and describes a broad spectrum of triggers that induce the formation of wormlike micelles or reversibly tune the morphology of surfactant aggregates from wormlike micelles to another state, or vice versa. Combining the fields of chemistry, physics, polymer science, and nanotechnology, its primary focus is on the design, formulation, and processing of intelligent viscoelastic surfactant solutions, covering the scientific principles governing responsiveness to one or more particular triggers, down to the end-use-driven functions. The first chapter explains why and how surfactants self-assemble into viscoelastic wormlike micellar solutions reminiscent of polymer solutions, while the following chapters show how the response to a given trigger translates into macroscopic rheological changes, including temperature, light, pH, CO2, redox, hydrocarbon, etc. The last chapter demonstrates the applications of these viscoelastic assemblies in oil and gas pro...

  18. Solubilization of Hydrophobic Dyes in Surfactant Solutions

    Directory of Open Access Journals (Sweden)

    Ali Reza Tehrani-Bagha

    2013-02-01

    Full Text Available In this paper, the use of surfactants for solubilization of hydrophobic organic dyes (mainly solvent and disperse dyes has been reviewed. The effect of parameters such as the chemical structures of the surfactant and the dye, addition of salt and of polyelectrolytes, pH, and temperature on dye solubilization has been discussed. Surfactant self-assemble into micelles in aqueous solution and below the concentration where this occurs—the critical micelle concentration (CMC—there is no solubilization. Above the CMC, the amount of solubilized dye increases linearly with the increase in surfactant concentration. It is demonstrated that different surfactants work best for different dyes. In general, nonionic surfactants have higher solubilization power than anionic and cationic surfactants. It is likely that the reason for the good performance of nonionic surfactants is that they allow dyes to be accommodated not only in the inner, hydrocarbon part of the micelle but also in the headgroup shell. It is demonstrated that the location of a dye in a surfactant micelle can be assessed from the absorption spectrum of the dye-containing micellar solution.

  19. Effect of hydrostatic pressure on gas solubilization in micelles.

    Science.gov (United States)

    Meng, Bin; Ashbaugh, Henry S

    2015-03-24

    Molecular dynamics simulations of anionic sodium decylsulfate and nonionic pentaethylene glycol monodecyl ether micelles in water have been performed to examine the impact of hydrostatic pressure on argon solubilization as a function of pressure. The potential-of-mean force between the micelles and argon demonstrates that nonpolar gases are attracted to the interiors of both micelles. The affinity of argon for micelle interiors, however, decreases with increasing pressure as a result of the comparatively higher molar volume of argon inside assemblies. We evaluate solubility enhancement coefficients, which describe the drop in the solute chemical potential as a function of the micellized surfactant concentration, to quantify the impact of micellization on gas solubilization. While argon is similarly attracted to the hydrophobic cores of both micelles, the gas is more effectively sequestered within nonionic micelles compared with anionic micelles as a result of salting out by charged head groups and accompanying counterions. The solubility enhancement coefficients of both micelles decrease with increasing pressure, reflecting the changing forces observed in the potentials-of-mean force. An analytical liquid drop model is proposed to describe the pressure dependence of argon solubilization within micelles that captures the simulation solubility enhancement coefficients after fitting an effective micelle radius for each surfactant.

  20. Surfactants enhance recovery of poorly soluble drugs during microdialysis sampling

    DEFF Research Database (Denmark)

    Koplin, Sebastian; Kumpugdee-Vollrath, Mont; Bauer-Brandl, Annette

    2017-01-01

    Aim of this project was to investigate the applicability of a recently developed in vitro microdialysis-sampling approach in connection with a dissolution-/permeation (D/P) system, especially the impact of surfactants within the perfusion fluid. The D/P-system is based on side-by-side chambers...... drug-dissolution (-release) and drug permeation. Furthermore, it should allow quantification of the unbound (free) drug concentration. In the first step, it was assessed, if the addition of the anionic surfactant sodium dodecyl sulphate (SDS) to the perfusate of the microdialysis system affects...... celecoxib, i.e. the fraction of drug, which is not associated with taurocholate surfactant micelles. In buffer, the measured concentrations matched the overall CXB concentrations. By the use of SDS-containing perfusates microdialysis sampling enabled reliable quantification of minute amounts of free CXB...

  1. Temperature Effect on Micelle Formation: Molecular Thermodynamic Model Revisited.

    Science.gov (United States)

    Khoshnood, Atefeh; Lukanov, Boris; Firoozabadi, Abbas

    2016-03-08

    Temperature affects the aggregation of macromolecules such as surfactants, polymers, and proteins in aqueous solutions. The effect on the critical micelle concentration (CMC) is often nonmonotonic. In this work, the effect of temperature on the micellization of ionic and nonionic surfactants in aqueous solutions is studied using a molecular thermodynamic model. Previous studies based on this technique have predicted monotonic behavior for ionic surfactants. Our investigation shows that the choice of tail transfer energy to describe the hydrophobic effect between the surfactant tails and the polar solvent molecules plays a key role in the predicted CMC. We modify the tail transfer energy by taking into account the effect of the surfactant head on the neighboring methylene group. The modification improves the description of the CMC and the predicted micellar size for aqueous solutions of sodium n-alkyl sulfate, dodecyl trimethylammonium bromide (DTAB), and n-alkyl polyoxyethylene. The new tail transfer energy describes the nonmonotonic behavior of CMC versus temperature. In the DTAB-water system, we redefine the head size by including the methylene group, next to the nitrogen, in the head. The change in the head size along with our modified tail transfer energy improves the CMC and aggregation size prediction significantly. Tail transfer is a dominant energy contribution in micellar and microemulsion systems. It also promotes the adsorption of surfactants at fluid-fluid interfaces and affects the formation of adsorbed layer at fluid-solid interfaces. Our proposed modifications have direct applications in the thermodynamic modeling of the effect of temperature on molecular aggregation, both in the bulk and at the interfaces.

  2. Shear-driven redistribution of surfactant affects enzyme activity in well-mixed femtoliter droplets.

    Science.gov (United States)

    Liu, Yu; Jung, Seung-Yong; Collier, C Patrick

    2009-06-15

    We developed a microfluidic platform for splitting well-mixed, femtoliter-volume droplets from larger water-in-oil plugs, where the sizes of the daughter droplets were not limited by channel width. These droplets were separated from mother plugs at a microfabricated T-junction, which enabled the study of how increased confinement affected enzyme kinetics in droplets 4-10 microm in diameter. Initial rates for enzyme catalysis in the mother plugs and the largest daughter drops were close to the average bulk rate, while the rates in smaller droplets decreased linearly with increasing surface to volume ratio. Rates in the smallest droplets decreased by a factor of 4 compared to the bulk rate. Traditional methods for detecting nonspecific adsorption at the water-oil interface were unable to detect evidence of enzyme adsorption, including pendant drop tensiometry, laser scanning confocal microscopy of drops containing labeled proteins in microemulsions, and epifluorescence microscopy of plugs and drops generated on-chip. We propose the slowing of enzyme reaction kinetics in the smaller droplets was the result of increased adsorption and inactivation of enzymes at the water-oil interface arising from transient interfacial shear stresses imparted on the daughter droplets as they split from the mother plugs and passed through the constricted opening of the T-junction. Such stresses are known to modulate the interfacial area and density of surfactant molecules that can passivate the interface. Bright field images of the splitting processes at the junction indicate that these stresses scaled with increasing surface to volume ratios of the droplets but were relatively insensitive to the average flow rate of plugs upstream of the junction.

  3. Synergism and Physicochemical Properties of Anionic/Amphoteric Surfactant Mixtures with Nonionic Surfactant of Amine Oxide Type

    Science.gov (United States)

    Blagojević, S. M.; Pejić, N. D.; Blagojević, S. N.

    2017-12-01

    The physicochemical properties of initial formulation, that is anionic/amphoteric surfactants mixture SLES/AOS/CAB (sodium lauryl ether sulfate (SLES), α-olefin sulfonates (AOS) and cocamidopropyl betaine (CAB) at ratio 80 : 15 : 5) with nonionic surfactant of amine oxide type (lauramine oxide (AO)) in various concentration (1-5%) were studied. To characterize the surfactants mixture, the critical micelle concentration (CMC), surface tension (γ), foam volume, biodegradability and irritability were determined. This study showed that adding of AO in those mixtures lowered both γ and CMC as well as enhanced SLES/AOS/CAB foaming properties, but did not significantly affect biodegradability and irritability of initial formulation. Moreover, an increase in AO concentration has a meaningful synergistic effect on the initial formulation properties. All those results indicates that a nonionic surfactant of amine oxide type significantly improves the performance of anionic/amphoteric mixed micelle systems, and because of that anionic/amphoteric/nonionic mixture can be used in considerably lower concentrations as a cleaning formulation.

  4. Splash Dynamics of Falling Surfactant-Laden Droplets

    Science.gov (United States)

    Sulaiman, Nur; Buitrago, Lewis; Pereyra, Eduardo

    2017-11-01

    Splashing dynamics is a common issue in oil and gas separation technology. In this study, droplet impact of various surfactant concentrations onto solid and liquid surfaces is studied experimentally using a high-speed imaging analysis. Although this area has been widely studied in the past, there is still not a good understanding of the role of surfactant over droplet impact and characterization of resulting splash dynamics. The experiments are conducted using tap water laden with anionic surfactant. The effects of system parameters on a single droplet impingement such as surfactant concentration (no surfactant, below, at and above critical micelle concentration), parent drop diameter (2-5mm), impact velocity and type of impact surface (thin and deep pool) are investigated. Image analysis technique is shown to be an effective technique for identification of coalescence to splashing transition. In addition, daughter droplets size distributions are analyzed qualitatively in the events of splashing. As expected, it is observed that the formation of secondary droplets is affected by the surfactant concentration. A summary of findings will be discussed.

  5. Chemical reactions in reverse micelle systems

    Science.gov (United States)

    Matson, Dean W.; Fulton, John L.; Smith, Richard D.; Consani, Keith A.

    1993-08-24

    This invention is directed to conducting chemical reactions in reverse micelle or microemulsion systems comprising a substantially discontinuous phase including a polar fluid, typically an aqueous fluid, and a microemulsion promoter, typically a surfactant, for facilitating the formation of reverse micelles in the system. The system further includes a substantially continuous phase including a non-polar or low-polarity fluid material which is a gas under standard temperature and pressure and has a critical density, and which is generally a water-insoluble fluid in a near critical or supercritical state. Thus, the microemulsion system is maintained at a pressure and temperature such that the density of the non-polar or low-polarity fluid exceeds the critical density thereof. The method of carrying out chemical reactions generally comprises forming a first reverse micelle system including an aqueous fluid including reverse micelles in a water-insoluble fluid in the supercritical state. Then, a first reactant is introduced into the first reverse micelle system, and a chemical reaction is carried out with the first reactant to form a reaction product. In general, the first reactant can be incorporated into, and the product formed in, the reverse micelles. A second reactant can also be incorporated in the first reverse micelle system which is capable of reacting with the first reactant to form a product.

  6. Critical micelle concentrations of allelopathic substances produced by Nannochloris oculata which affect a red tide organism, Gymnodinium breve.

    Science.gov (United States)

    Pérez, E; Martin, D F

    2001-01-01

    Laboratory cultures of the green algae Nannochloris oculata and Nannochloris eucaryotum are known to cause lysis of Gymnodinium breve, which is Florida's red tide organism. Two cytolytic agents were previously identified as methyl palmitate and methyl stearate. In this study, the critical micelle concentrations of these substances were determined by ultraviolet light and turbidimetric methods to be 3.5 +/- 0.3 ppm (methyl stearate) and 4.3 +/- 0.6 (methyl palmitate). There were no significant differences in results obtained using the two methods.

  7. Micelles as Soil and Water Decontamination Agents.

    Science.gov (United States)

    Shah, Afzal; Shahzad, Suniya; Munir, Azeema; Nadagouda, Mallikarjuna N; Khan, Gul Shahzada; Shams, Dilawar Farhan; Dionysiou, Dionysios D; Rana, Usman Ali

    2016-05-25

    Contaminated soil and water pose a serious threat to human health and ecosystem. For the treatment of industrial effluents or minimizing their detrimental effects, preventive and remedial approaches must be adopted prior to the occurrence of any severe environmental, health, or safety hazard. Conventional treatment methods of wastewater are insufficient, complicated, and expensive. Therefore, a method that could use environmentally friendly surfactants for the simultaneous removal of both organic and inorganic contaminants from wastewater is deemed a smart approach. Surfactants containing potential donor ligands can coordinate with metal ions, and thus such compounds can be used for the removal of toxic metals and organometallic compounds from aqueous systems. Surfactants form host-guest complexes with the hydrophobic contaminants of water and soil by a mechanism involving the encapsulation of hydrophobes into the self-assembled aggregates (micelles) of surfactants. However, because undefined amounts of surfactants may be released into the aqueous systems, attention must be paid to their own environmental risks as well. Moreover, surfactant remediation methods must be carefully analyzed in the laboratory before field implementation. The use of biosurfactants is the best choice for the removal of water toxins as such surfactants are associated with the characteristics of biodegradability, versatility, recovery, and reuse. This Review is focused on the currently employed surfactant-based soil and wastewater treatment technologies owing to their critical role in the implementation of certain solutions for controlling pollution level, which is necessary to protect human health and ensure the quality standard of the aquatic environment.

  8. Constraint and flow: Poiseuille shear response of a surfactant ...

    Indian Academy of Sciences (India)

    Abstract. To minimize their free energy in aqueous solution, surfactant molecules self-assemble to form some basic morphologies – globular micelles, highly extended thead- like micelles and membrane bilayers – which themselves order to display a rich variety of mesophase symmetries and properties. In membrane ...

  9. Specific interactions within micelle microenvironment in different charged dye/surfa

    Directory of Open Access Journals (Sweden)

    Adina Roxana Petcu

    2016-01-01

    Full Text Available The interactions of two ionic dyes, Crystal Violet and Methyl Orange, with different charged surfactants and also with a nonionic surfactant were investigated using surface tension measurements and visible spectroscopy in pre-micellar and post-micellar regions. It was found that for the water dominant phase systems the dye was localized between the polar heads, at the exterior of the direct micelle shells for all the systems. For the oil dominant phase systems, in case of the same charged dye/surfactant couples, the dye was localized in the micelle shell between the hydrocarbon chain of the surfactant nearby the hydrophilic head groups while for nonionic surfactant and oppositely charged dye/surfactant, localization of dye was between the oxyethylenic head groups towards the interior of the micelle core. Mixed aggregates of the dye and surfactant (below the critical micellar concentration of cationic surfactant, dye-surfactant ion pair and surfactant-micelles were present. The values of equilibrium constants (for TX-114/MO and TX-114/CV systems were 0.97 and 0.98, respectively, partition coefficients between the micellar and bulk water phases and standard free energy (for the nonionic systems were −12.59 kJ/mol for MO and −10.97 kJ/mol for CV were calculated for all the studied systems. The partition processes were exothermic and occurred spontaneously.

  10. Does Whole-Body Hypothermia in Neonates with Hypoxic-Ischemic Encephalopathy Affect Surfactant Disaturated-Phosphatidylcholine Kinetics?

    Science.gov (United States)

    Nespeca, Matteo; Giorgetti, Chiara; Nobile, Stefano; Ferrini, Ilaria; Simonato, Manuela; Verlato, Giovanna; Cogo, Paola; Carnielli, Virgilio Paolo

    2016-01-01

    It is unknown whether Whole-Body Hypothermia (WBH) affects pulmonary function. In vitro studies, at relatively low temperatures, suggest that hypothermia may induce significant changes to the surfactant composition. The effect of WBH on surfactant kinetics in newborn infants is unknown. We studied in vivo kinetics of disaturated-phosphatidylcholine (DSPC) in asphyxiated newborns during WBH and in normothermic controls (NTC) with no or mild asphyxia. Both groups presented no clinically apparent lung disease. Twenty-seven term or near term newborns requiring mechanical ventilation were studied (GA 38.6±2.2 wks). Fifteen during WBH and twelve NTC. All infants received an intra-tracheal dose of 13C labelled DSPC and tracheal aspirate were performed. DSPC amount, DSPC half-life (HL) and pool size (PS) were calculated. DSPC amount in tracheal aspirates was 0.42 [0.22-0.54] and 0.36 [0.10-0.58] mg/ml in WBH and NTC respectively (p = 0.578). DSPC HL was 24.9 [15.7-52.5] and 25.3 [15.8-59.3] h (p = 0.733) and DSPC PS was 53.2 [29.4-91.6] and 40.2 [29.8-64.6] mg/kg (p = 0.598) in WBH and NTC respectively. WBH does not alter DSPC HL and PS in newborn infants with no clinical apparent lung disease.

  11. Practical Considerations and Challenges Involved in Surfactant Enhanced Bioremediation of Oil

    Directory of Open Access Journals (Sweden)

    Sagarika Mohanty

    2013-01-01

    Full Text Available Surfactant enhanced bioremediation (SEB of oil is an approach adopted to overcome the bioavailability constraints encountered in biotransformation of nonaqueous phase liquid (NAPL pollutants. Fuel oils contain n-alkanes and other aliphatic hydrocarbons, monoaromatics, and polynuclear aromatic hydrocarbons (PAHs. Although hydrocarbon degrading cultures are abundant in nature, complete biodegradation of oil is rarely achieved even under favorable environmental conditions due to the structural complexity of oil and culture specificities. Moreover, the interaction among cultures in a consortium, substrate interaction effects during the degradation and ability of specific cultures to alter the bioavailability of oil invariably affect the process. Although SEB has the potential to increase the degradation rate of oil and its constituents, there are numerous challenges in the successful application of this technology. Success is dependent on the choice of appropriate surfactant type and dose since the surfactant-hydrocarbon-microorganism interaction may be unique to each scenario. Surfactants not only enhance the uptake of constituents through micellar solubilization and emulsification but can also alter microbial cell surface characteristics. Moreover, hydrocarbons partitioned in micelles may not be readily bioavailable depending on the microorganism-surfactant interactions. Surfactant toxicity and inherent biodegradability of surfactants may pose additional challenges as discussed in this review.

  12. Kinetics and mechanism for the sonochemical degradation of a nonionic surfactant.

    Science.gov (United States)

    Singla, Ritu; Grieser, Franz; Ashokkumar, Muthupandian

    2009-03-26

    The sonolytic degradation of the nonionic surfactant, octaethylene glycol monododecyl ether (C(12)E(8)), has been studied at various initial concentrations below and above its critical micelle concentration (CMC). It has been observed that the degradation rate increases with an increase in the initial concentration of the surfactant until the CMC is reached. Above the CMC an almost constant degradation rate is observed, suggesting that the surfactant in its monomer form is involved in the degradation process. The degradation process of C(12)E(8) involves two distinct primary processes occurring at the bubble/solution interface: (a) hydroxylation/oxidation of the surfactant and (b) pyrolytic fragmentation of the surfactant. The oxidative cleavage of ethylene oxide units provides evidence for OH radical attack. Hydroxylation of the ethoxy chain gives rise to various short-chain carboxyalkyl-polyethylene glycol intermediates. The polyethylene glycol chain formed, due to the scission of the C(12)E(8) molecule, undergoes rapid hydroxylation/oxidation to yield simple compounds that have the potential to undergo further degradation. The detection of multiple intermediates indicates that several processes affect the complete degradation pathways of the surfactant molecule. TOC analysis, however, indicates that the sonolytic mineralization of the surfactant is difficult to achieve at reasonable rates due to the relatively low surface activity of the degradation products formed during sonolysis.

  13. Practical Considerations and Challenges Involved in Surfactant Enhanced Bioremediation of Oil

    Science.gov (United States)

    Mohanty, Sagarika; Jasmine, Jublee

    2013-01-01

    Surfactant enhanced bioremediation (SEB) of oil is an approach adopted to overcome the bioavailability constraints encountered in biotransformation of nonaqueous phase liquid (NAPL) pollutants. Fuel oils contain n-alkanes and other aliphatic hydrocarbons, monoaromatics, and polynuclear aromatic hydrocarbons (PAHs). Although hydrocarbon degrading cultures are abundant in nature, complete biodegradation of oil is rarely achieved even under favorable environmental conditions due to the structural complexity of oil and culture specificities. Moreover, the interaction among cultures in a consortium, substrate interaction effects during the degradation and ability of specific cultures to alter the bioavailability of oil invariably affect the process. Although SEB has the potential to increase the degradation rate of oil and its constituents, there are numerous challenges in the successful application of this technology. Success is dependent on the choice of appropriate surfactant type and dose since the surfactant-hydrocarbon-microorganism interaction may be unique to each scenario. Surfactants not only enhance the uptake of constituents through micellar solubilization and emulsification but can also alter microbial cell surface characteristics. Moreover, hydrocarbons partitioned in micelles may not be readily bioavailable depending on the microorganism-surfactant interactions. Surfactant toxicity and inherent biodegradability of surfactants may pose additional challenges as discussed in this review. PMID:24350261

  14. Charging and Screening in Nonpolar Solutions of Nonionizable Surfactants

    Science.gov (United States)

    Behrens, Sven

    2010-03-01

    Nonpolar liquids do not easily accommodate electric charges, but surfactant additives are often found to dramatically increase the solution conductivity and promote surface charging of suspended colloid particles. Such surfactant-mediated electrostatic effects have been associated with equilibrium charge fluctuations among reverse surfactant micelles and in some cases with the statistically rare ionization of individual surfactant molecules. Here we present experimental evidence that even surfactants without any ionizable group can mediate charging and charge screening in nonpolar oils, and that they can do so at surfactant concentrations well below the critical micelle concentration (cmc). Precision conductometry, light scattering, and Karl-Fischer titration of sorbitan oleate solutions in hexane, paired with electrophoretic mobility measurements on suspended polymer particles, reveal a distinctly electrostatic action of the surfactant. We interpret our observations in terms of a charge fluctuation model and argue that the observed charging processes are likely facilitated, but not limited, by the presence of ionizable impurities.

  15. Surfactant Membrane Phases Containing Mixtures of Hydrocarbon and Fluorocarbon Surfactants

    International Nuclear Information System (INIS)

    de Campo, Liliana; Warr, G.G.

    2005-01-01

    Full text: We describe the structure and stability of sponge and lamellar phases comprising mixtures of hydrocarbon and fluorocarbon surfactants. Such mixtures can show limited miscibility with each other, forming for example coexisting populations of hydrocarbon rich and fluorocarbon rich micelles under some circumstances. Our system is based on the well-characterised lamellar and sponge phases of cetylpyridinium chloride, hexanol and 0.2M brine, into which the partially fluorinated surfactant N-1H,1H,2H,2H-tridecafluorooctylpyridinium chloride is incorporated. By probing the structures with SAXS (small angle x-ray scattering) and SANS (small angle neutron scattering) using contrast variation, and by characterizing the dynamic properties with dynamic light scattering, we will describe the effect of incorporating the fluorinated surfactant on the phase equilibria and properties of the surfactant membrane structures. (authors)

  16. Synthesis and immobilization of polystyreneb-polyvinyltriethoxysilane micelles

    KAUST Repository

    Zhu, Saisai

    2018-01-31

    Diblock copolymers polystyrene-block-polyvinyltriethoxysilane (PS-b-PVTES) were synthesized via atom transfer radical polymerization (ATRP), which self-assembled into spherical micelles in solvent of THF-methanol mixtures. The self-assembled micelles were immobilized by cross-linking reaction of VTES in a shell layer of micelles. The chemical structures of block copolymers and morphology of micelles were characterized in detail. It was found that the size of immobilized micelles was strongly affected by the copolymer concentration, composition of mixture solvent, and block ratios.

  17. Dimeric Surfactants: Promising Ingredients of Cosmetics and Toiletries

    Directory of Open Access Journals (Sweden)

    Naveen Kumar

    2013-11-01

    Full Text Available Surfactants are an essential ingredient for cosmetic, toiletries and personal care products for enhancing their performance. Dimeric surfactants demonstrate superiority compared to conventional surfactants in all areas of application. Dimeric surfactants are extremely promising for utilization in various cosmetic formulations viz. shampoo, lotions, creams, conditioners etc. These surfactants possess extremely unique surface properties viz. lower surface tension, unique micellization, low critical micelle concentration (CMC and antimicrobial activity, higher solubilization etc. Dimerics enhance the performances of cosmetics in an extraordinary manner and provide eco-friendly preparations for human epidermis.

  18. Flow of wormlike micelles in an expansion-contraction geometry

    NARCIS (Netherlands)

    Stukan, Mikhail R.; Boek, Edo S.; Boek, E.S.; Padding, J.T.; Briels, Willem J.; Crawshaw, John P.

    2008-01-01

    Recently there has been a great deal of attention, from researchers both in academia and in industry, focused on the rheological properties of solutions of viscoelastic wormlike micelles formed by surfactants. It is particularly vital to understand the properties of these solutions with regard to

  19. 开关型表面活性剂胶束为模板合成CdS量子点%Facile Synthesis of CdS Quantum Dots in Surfactant Micelles

    Institute of Scientific and Technical Information of China (English)

    何艳娥; 张婷; 代利; 蒋建中; 崔正刚

    2013-01-01

    In this article,CdS quantum dots have been synthesized in micelles system.The micelle could be broken easily and CdS quantum dots could be obtained by simple centrifugation and washing.The quantum dots were then characterized by TEM,XRD.The method using micelles as soft template to prepare CdS quantum dots can be widely applied to synthesize other nanoparticles.%以开关型表面活性剂N'-十二烷基-N,N-二甲基乙基脒碳酸氢盐胶束溶液为软模板合成CdS纳米粒子,反应结束后向体系中通入N2并加热至65℃使体系破乳,该过程避免了传统表面活性剂胶束的繁琐破乳过程.合成的CdS纳米粒子通过TEM、XRD进行表征,结果表明以该表面活性剂胶束为软模板可合成粒径在10 nm以下、具有纳米光学效应的CdS量子点.

  20. Interaction of primaquine and chloroquine with ionic micelles: 1 H NMR and electronic absorption spectroscopy

    International Nuclear Information System (INIS)

    Perussi, Janice R.; Monte, Shirley C.; Imasato, Hidetake; Tabak, Marcel; Yushmanov, Victor E.

    1995-01-01

    The characteristic of binding of primaquine (PQ) and chloroquine (CQ) to micelles of surfactants with different charge of headgroups were studied by 1 H-NMR and optical absorption spectroscopy. Cetyltrimethylammonium (CTAC) was used as a cationic surfactant, sodium dodecylsulfate (SDS) as an anionic surfactant and N-hexadecyl-N, N-dimethyl-3-ammonio-1-propanesulfonate (HPS) as zwitterionic. The pK values and binding constants were estimated. (author)

  1. Tunable, antibacterial activity of silicone polyether surfactants.

    Science.gov (United States)

    Khan, Madiha F; Zepeda-Velazquez, Laura; Brook, Michael A

    2015-08-01

    Silicone surfactants are used in a variety of applications, however, limited data is available on the relationship between surfactant structure and biological activity. A series of seven nonionic, silicone polyether surfactants with known structures was tested for in vitro antibacterial activity against Escherichia coli BL21. The compounds varied in their hydrophobic head, comprised of branched silicone structures with 3-10 siloxane linkages and, in two cases, phenyl substitution, and hydrophilic tail of 8-44 poly(ethylene glycol) units. The surfactants were tested at three concentrations: below, at, and above their Critical Micelle Concentrations (CMC) against 5 concentrations of E. coli BL21 in a three-step assay comprised of a 14-24h turbidometric screen, a live-dead stain and viable colony counts. The bacterial concentration had little effect on antibacterial activity. For most of the surfactants, antibacterial activity was higher at concentrations above the CMC. Surfactants with smaller silicone head groups had as much as 4 times the bioactivity of surfactants with larger groups, with the smallest hydrophobe exhibiting potency equivalent to sodium dodecyl sulfate (SDS). Smaller PEG chains were similarly associated with higher potency. These data link lower micelle stability and enhanced permeability of smaller silicone head groups to antibacterial activity. The results demonstrate that simple manipulation of nonionic silicone polyether structure leads to significant changes in antibacterial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Fluorescence imaging of sample zone narrowing and dispersion in a glass microchip: the effects of organic solvent (acetonitrile)-salt mixtures in the sample matrix and surfactant micelles in the running buffer.

    Science.gov (United States)

    Jia, Zhijian; Lee, Yi-kuen; Fang, Qun; Huie, Carmen W

    2006-03-01

    A mismatch in the EOF velocities between the sample zone and running buffer region is known to generate pressure-driven, parabolic flow profile of the sample plug in electrokinetic separation systems. In the present study, video fluorescence microscopy was employed to capture real-time dynamics of the sample plug (containing fluorescein as the probe molecule) in a discontinuous conductivity system within a glass microchip, in which the sample matrix consisted of a mixture of ACN and salt (NaCl), and the running buffer contained sodium cholate (SC) micelles as the pseudo-stationary phase (i.e., performing "ACN stacking" in the mode of MEKC). Upon application of the separation voltage, the video images revealed that zone narrowing and broadening of the probe molecules occurred as the sample plug headed toward the cathode during the initial time period, probably resulting in part from the stacking/sweeping, and destacking of the SC micelles at the boundaries between the sample zone and running buffer. Interestingly, a second sample zone narrowing event can be observed as the sample plug moved further toward the cathode, which could be attributed to the sweeping of the slower moving probe molecules by the faster moving SC micelles that originated from the anode. This phenomenon was studied as a function of pH, sample plug length, as well as the concentration of organic solvent and salt in the sample matrix. The data suggested that the presence of large amounts of an organic solvent (such as ACN or methanol) and salts in the sample matrix not only induces sample dispersion due to the formation of a pressure-driven (hydrodynamic) flow, but may also lead to the formation of a double sample zone narrowing phenomenon by altering the local EOF dynamics within the separation system.

  3. New self-assembled nanocrystal micelles for biolabels and biosensors.

    Energy Technology Data Exchange (ETDEWEB)

    Tallant, David Robert; Wilson, Michael C. (University of New Mexico, Albuquerque, NM); Leve, Erik W. (University of New Mexico, Albuquerque, NM); Fan, Hongyou; Brinker, C. Jeffrey; Gabaldon, John (University of New Mexico, Albuquerque, NM); Scullin, Chessa (University of New Mexico, Albuquerque, NM)

    2005-12-01

    The ability of semiconductor nanocrystals (NCs) to display multiple (size-specific) colors simultaneously during a single, long term excitation holds great promise for their use in fluorescent bio-imaging. The main challenges of using nanocrystals as biolabels are achieving biocompatibility, low non-specific adsorption, and no aggregation. In addition, functional groups that can be used to further couple and conjugate with biospecies (proteins, DNAs, antibodies, etc.) are required. In this project, we invented a new route to the synthesis of water-soluble and biocompatible NCs. Our approach is to encapsulate as-synthesized, monosized, hydrophobic NCs within the hydrophobic cores of micelles composed of a mixture of surfactants and phospholipids containing head groups functionalized with polyethylene glycol (-PEG), -COOH, and NH{sub 2} groups. PEG provided biocompatibility and the other groups were used for further biofunctionalization. The resulting water-soluble metal and semiconductor NC-micelles preserve the optical properties of the original hydrophobic NCs. Semiconductor NCs emit the same color; they exhibit equal photoluminescence (PL) intensity under long-time laser irradiation (one week) ; and they exhibit the same PL lifetime (30-ns). The results from transmission electron microscopy and confocal fluorescent imaging indicate that water-soluble semiconductor NC-micelles are biocompatible and exhibit no aggregation in cells. We have extended the surfactant/lipid encapsulation techniques to synthesize water-soluble magnetic NC-micelles. Transmission electron microscopy results suggest that water-soluble magnetic NC-micelles exhibit no aggregation. The resulting NC-micelles preserve the magnetic properties of the original hydrophobic magnetic NCs. Viability studies conducted using yeast cells suggest that the magnetic nanocrystal-micelles are biocompatible. We have demonstrated, for the first time, that using external oscillating magnetic fields to manipulate

  4. Effect of a cationic surfactant on the volatilization of PAHs from soil.

    Science.gov (United States)

    Lu, Li; Zhu, Lizhong

    2012-06-01

    Cationic surfactants are common in soils because of their use in daily cosmetic and cleaning products, and their use as a soil amendment for the mitigation and remediation of organic contaminated soils has been proposed. Such surfactant may affect the transfer and fate of organic contaminants in the environment. This study investigated the effect of a cationic surfactant, dodecylpyridinium bromide (DDPB), on the volatilization of polycyclic aromatic hydrocarbons (PAHs) from a paddy soil. The volatilization of PAHs from moist soil amended with different concentrations of DDPB was tested in an open system. The specific effects of DDPB on the liquid-vapor and solid-vapor equilibriums of PAHs were separately investigated in closed systems by headspace analysis. DDPB affects both liquid-vapor and solid-vapor processes of PAHs in soil. At DDPB concentrations below the critical micelle concentration (CMC), movement of PAHs from the bulk solution to the gas-liquid interface appeared to be facilitated by interaction between PAHs and the surfactant monomers adsorbed at the gas-liquid interface, promoting the volatilization of PAHs from solution. However, when DDPB was greater than the CMC, volatilization was inhibited due to the solubilization of PAHs by micelles. On the other hand, the formation of sorbed surfactant significantly inhibited the solid-vapor volatilization of PAHs. The overall effect of the two simultaneous effects of DDPB on liquid-vapor and solid-vapor processes was a decreased volatilization loss of PAHs from soil. Inhibition of PAH volatilization was more significant for the soil with a lower moisture content.

  5. Aggregation work at polydisperse micellization: ideal solution and "dressed micelle" models comparing to molecular dynamics simulations.

    Science.gov (United States)

    Burov, S V; Shchekin, A K

    2010-12-28

    General thermodynamic relations for the work of polydisperse micelle formation in the model of ideal solution of molecular aggregates in nonionic surfactant solution and the model of "dressed micelles" in ionic solution have been considered. In particular, the dependence of the aggregation work on the total concentration of nonionic surfactant has been analyzed. The analogous dependence for the work of formation of ionic aggregates has been examined with regard to existence of two variables of a state of an ionic aggregate, the aggregation numbers of surface active ions and counterions. To verify the thermodynamic models, the molecular dynamics simulations of micellization in nonionic and ionic surfactant solutions at two total surfactant concentrations have been performed. It was shown that for nonionic surfactants, even at relatively high total surfactant concentrations, the shape and behavior of the work of polydisperse micelle formation found within the model of the ideal solution at different total surfactant concentrations agrees fairly well with the numerical experiment. For ionic surfactant solutions, the numerical results indicate a strong screening of ionic aggregates by the bound counterions. This fact as well as independence of the coefficient in the law of mass action for ionic aggregates on total surfactant concentration and predictable behavior of the "waterfall" lines of surfaces of the aggregation work upholds the model of "dressed" ionic aggregates.

  6. Electrostatic Screening and Charge Correlation Effects in Micellization of Ionic Surfactants

    KAUST Repository

    Jusufi, Arben; Hynninen, Antti-Pekka; Haataja, Mikko; Panagiotopoulos, Athanassios Z.

    2009-01-01

    We have used atomistic simulations to study the role of electrostatic screening and charge correlation effects in self-assembly processes of ionic surfactants into micelles. Specifically, we employed grand canonical Monte Carlo simulations

  7. Effect of surfactants on the spectrofluorimetric properties of zearalenone

    International Nuclear Information System (INIS)

    Appell, Michael; Bosma, Wayne B.

    2011-01-01

    The chemiluminescent properties of the estrogenic mycotoxin zearalenone in the presence of aqueous micellar media were investigated using steady state fluorescence techniques. Micelles of surfactants sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (CTAB), and non-ionic Triton X-100 enhanced the fluorescence intensity of zearalenone in aqueous solutions. The binding constants have been determined and indicate zearalenone has the highest affinity for Triton X-100, followed by CTAB, and then by SDS. The encapsulation of zearalenone by the micelles studied is spontaneous and exothermic. The selective microenvironments provided by organized micellar systems offer an attractive medium to modulate fluorescence detection of zearalenone. - Highlights: → Surfactants can selectively modulate the fluorescence detection of zearalenone. → Binding studies provide information on the zearalenone-surfactant interactions. → Fluorescence intensity of zearalenone is related to the micelle microenvironment.

  8. Formation of nanoparticles on reverse micelles: SANS studies

    International Nuclear Information System (INIS)

    Sim, Jae-Hyun; Park, Jaejung; Kim, Myungwoong; Hwan Bang, Jeong; Park, Sangwook; Sohn, Daewon

    2006-01-01

    The structure of polymethyl methacrylate (PMMA) on the surface of reverse micelles was investigated by small-angle neutron scattering (SANS). The water-in-oil microemulsion containing initiators in the inner part of reverse micelle was prepared with surfactant, poly(oxyethylene) nonylphenyl ether (NP5, H(CH 2 ) 9 Ph(OC 2 H 4 ) 5 OH), water, cyclohexane and adequate initiators, sodium metabisulfate (SDS) and potassium persulfate (KPS), for aimed polymerization (PMMA). Various model fittings such as the core-shell sphere model and hard sphere model containing smearing effect reveal that polymer shell thickness changes from 52 to 60 A, respectively, with increase of monomer concentration

  9. Polymorphism in SFTPD gene affects assembly and constitutional serum levels of surfactant protein D in a Lebanese population

    DEFF Research Database (Denmark)

    Fakih, Dalia; Chamat, Soulaima; Medlej-Hashim, Myrna

    2014-01-01

    Surfactant protein D (SP-D), an oligomeric lung-derived lectin, has essential roles in innate immunity. It can be measured in serum. Previous studies have shown that constitutional SP-D serum levels and the protein degree of multimerization are genetically influenced. We aimed to establish the di...

  10. Logarithmic Exchange Kinetics in Monodisperse Copolymeric Micelles

    Science.gov (United States)

    García Daza, Fabián A.; Bonet Avalos, Josep; Mackie, Allan D.

    2017-06-01

    Experimental measurements of the relaxation kinetics of copolymeric surfactant exchange for micellar systems unexpectedly show a peculiar logarithmic decay. Several authors use polydispersity as an explanation for this behavior. However, in coarse-grained simulations that preserve microscopic details of the surfactants, we find evidence of the same logarithmic behavior. Since we use a strictly monodisperse distribution of chain lengths such a relaxation process cannot be attributed to polydispersity, but has to be caused by an inherent physical process characteristic of this type of system. This is supported by the fact that the decay is specifically logarithmic and not a power law with an exponent inherited from the particular polydispersity distribution of the sample. We suggest that the degeneracy of the energy states of the hydrophobic block in the core, which is broken on leaving the micelle, can qualitatively explain the broad distribution of energy barriers, which gives rise to the observed nonexponential relaxation.

  11. The role of charge in the surfactant-assisted stabilization of the natural product curcumin.

    Science.gov (United States)

    Wang, Zifan; Leung, Mandy H M; Kee, Tak W; English, Douglas S

    2010-04-20

    Colloidal solutions of surfactants that form micelles or vesicles are useful for solubilizing and stabilizing hydrophobic molecules that are otherwise sparingly soluble in aqueous solutions. In this paper we investigate the use of micelles and vesicles prepared from ionic surfactants for solubilizing and stabilizing curcumin, a medicinal natural product that undergoes alkaline hydrolysis in water. We identify spectroscopic signatures to evaluate curcumin partitioning and deprotonation in surfactant mixtures containing micelles or vesicles. These spectroscopic signatures allow us to monitor the interaction of curcumin with charged surfactants over a wide range of pH values. Titration data are presented to show the pH dependence of curcumin interactions with negatively and positively charged micelles and vesicles. In solutions of cationic micelles or positively charged vesicles, strong interaction between the Cur(-1) phenoxide ion and the positively charged surfactants results in a change in the acidity of the phenolic hydrogen and a lowering of the apparent lowest pK(a) value for curcumin. In the microenvironments formed by anionic micelles or negatively charged bilayers, our data indicates that curcumin partitions as the Cur(0) species, which is stabilized by interactions with the respective surfactant aggregates, and this leads to an increase in the apparent pK(a) values. Our results may explain some of the discrepancies within the literature with respect to reported pK(a) values and the acidity of the enolic versus phenolic protons. Hydrolysis rates, quantum yields, and molar absorption coefficients are reported for curcumin in a variety of solutions.

  12. Influence of surfactants in forced dynamic dewetting.

    Science.gov (United States)

    Henrich, Franziska; Fell, Daniela; Truszkowska, Dorota; Weirich, Marcel; Anyfantakis, Manos; Nguyen, Thi-Huong; Wagner, Manfred; Auernhammer, Günter K; Butt, Hans-Jürgen

    2016-09-20

    In this work we show that the forced dynamic dewetting of surfactant solutions depends sensitively on the surfactant concentration. To measure this effect, a hydrophobic rotating cylinder was horizontally half immersed in aqueous surfactant solutions. Dynamic contact angles were measured optically by extrapolating the contour of the meniscus to the contact line. Anionic (sodium 1-decanesulfonate, S-1DeS), cationic (cetyl trimethylammonium bromide, CTAB) and nonionic surfactants (C 4 E 1 , C 8 E 3 and C 12 E 5 ) with critical micelle concentrations (CMCs) spanning four orders of magnitude were used. The receding contact angle in water decreased with increasing velocity. This decrease was strongly enhanced when adding surfactant, even at surfactant concentrations of 10% of the critical micelle concentration. Plots of the receding contact angle-versus-velocity almost superimpose when being plotted at the same relative concentration (concentration/CMC). Thus the rescaled concentration is the dominating property for dynamic dewetting. The charge of the surfactants did not play a role, thus excluding electrostatic effects. The change in contact angle can be interpreted by local surface tension gradients, i.e. Marangoni stresses, close to the three-phase contact line. The decrease of dynamic contact angles with velocity follows two regimes. Despite the existence of Marangoni stresses close to the contact line, for a dewetting velocity above 1-10 mm s -1 the hydrodynamic theory is able to describe the experimental results for all surfactant concentrations. At slower velocities an additional steep decrease of the contact angle with velocity was observed. Particle tracking velocimetry showed that the flow profiles do not differ with and without surfactant on a scales >100 μm.

  13. Studies of bio-mimetic medium of ionic and non-ionic micelles by a simple charge transfer fluorescence probe N,N-dimethylaminonapthyl-(acrylo)-nitrile

    Science.gov (United States)

    Samanta, Anuva; Paul, Bijan Kumar; Guchhait, N.

    2011-05-01

    In this report we have studied micellization process of anionic, cationic and non-ionic surfactants using N,N-dimethylaminonapthyl-(acrylo)-nitrile (DMANAN) as an external fluorescence probe. Micropolarity, microviscosity, critical micellar concentration of these micelles based on steady state absorption and fluorescence and time resolved emission spectroscopy of the probe DMANAN show that the molecule resides in the micelle-water interface for ionic micelles and in the core for the non-ionic micelle. The effect of variation of pH of the micellar solution as well as fluorescence quenching measurements of DMANAN provide further support for the location of the probe in the micelles.

  14. Characterization of lipase in reversed micelles formulated by Cibacron Blue F-3GA modified Span 85

    DEFF Research Database (Denmark)

    Zhang, Dong Hao; Guo, Zheng; Sun, Yan

    2007-01-01

    Sorbitan trioleate (Span 85) modified by Cibacron Blue F-3GA (CB) was prepared and used as an affinity surfactant to formulate a reversed micellar system for Candida rugosa lipase (CRL) solubilization. The system was characterized and evaluated by employing CRL-catalyzed hydrolysis of olive oil...... of the encapsulated lipase remained unchanged, but the apparent activity was significantly higher than that of the native enzyme in bulk solution. Kinetic studies indicated that the encapsulated lipase in the reversed micelles of CB-formulated Span 85 followed the Michaelis-Menten equation. The Michaelis constant...... was found to decrease with increasing surfactant concentration, suggesting an increase of the enzyme affinity for the substrate. Stability of the lipase in the reversed micelles was negatively correlated to W0. Introduction Reversed micelles are nanometer-scale transparent aggregates of water and surfactant...

  15. Surface properties and aggregate morphology of partially fluorinated carboxylate-type anionic gemini surfactants.

    Science.gov (United States)

    Yoshimura, Tomokazu; Bong, Miri; Matsuoka, Keisuke; Honda, Chikako; Endo, Kazutoyo

    2009-11-01

    Three anionic homologues of a novel partially fluorinated carboxylate-type anionic gemini surfactant, N,N'-di(3-perfluoroalkyl-2-hydroxypropyl)-N,N'-diacetic acid ethylenediamine (2C(n)(F) edda, where n represents the number of carbon atoms in the fluorocarbon chain (4, 6, and 8)) were synthesized. In these present gemini surfactants, the relatively small carboxylic acid moieties form hydrophilic head groups. The surface properties or structures of the aggregates of these surfactants are strongly influenced by the nonflexible fluorocarbons and small head groups; this is because these surfactants have a closely packed molecular structure. The equilibrium surface tension properties of these surfactants were measured at 298.2K for various fluorocarbon chain lengths. The plot of the logarithm of the critical micelle concentration (cmc) against the fluorocarbon chain lengths for 2C(n)(F) edda (n=4, 6, and 8) showed a minimum for n=6. Furthermore, the lowest surface tension of 2C(6)(F) edda at the cmc was 16.4mNm(-1). Such unique behavior has not been observed even in the other fluorinated surfactants. Changes in the shapes and sizes of these surfactant aggregate with concentration were investigated by dynamic light scattering and transmission electron microscopy (TEM). The TEM micrographs showed that in an aqueous alkali solution, 2C(n)(F) edda mainly formed aggregates with stringlike (n=4), cagelike (n=6), and distorted bilayer structures (n=8). The morphological changes in the aggregates were affected by the molecular structure composed of nonflexible fluorocarbon chains and flexible hydrocarbon chains.

  16. Emulsion stability and properties of fish gelatin-based films as affected by palm oil and surfactants.

    Science.gov (United States)

    Nilsuwan, Krisana; Benjakul, Soottawat; Prodpran, Thummanoon

    2016-05-01

    Gelatin films exhibit the poor water vapour barrier properties. The use of palm oil, which is abundant and available in Thailand, can be a means to lower water vapour migration. To disperse oil in film-forming dispersion (FFD), a surfactant along with appropriate homogenization is required. The study aimed to investigate the influence of palm oil level and surfactants in the absence or presence of glycerol on characteristics of FFD and resulting gelatin films. Similar oil droplet sizes, both d32 and d43 values, of FFD containing soy lecithin were observed, regardless of palm oil level used (P > 0.05). FFD with Tween-20 had larger droplet size as the levels of oil increased (P palm oil level increased (P 0.05). FFD containing 500 or 750 g kg(-1) palm oil using soy lecithin as a surfactant in the presence of 300 g kg(-1) glycerol had the enhanced homogeneity and stability of oil droplets. The resulting gelatin film had the improved water vapour barrier properties. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  17. Theoretical and Simulations-Based Modeling of Micellization in Linear and Branched Surfactant Systems

    Science.gov (United States)

    Mendenhall, Jonathan D.

    Surfactants are chemically-heterogeneous molecules possessing hydrophilic (head) and hydrophobic (tail) moieties. This dual nature of surfactants leads to interesting phase behavior in aqueous solution as a function of surfactant concentration, including: (i) formation of surfactant monolayers at surfaces and interfaces, and (ii) self-assembly into finite aggregates (micelles) in the bulk solution beyond the critical micelle concentration (cmc). This concentration-dependent phase behavior induces changes in solution properties. For example, the surface activity of surfactants can decrease the surface tension, and self-assembly in bulk solution can lead to changes in viscosity, equivalent conductivity, solubilization capacity, and other bulk properties. These effects make surfactants quite attractive and unique for use in product formulations, where they are utilized as detergents, dispersants, emulsifiers, solubilizers, surface and interfacial tension modifiers, and in other contexts. The specific chemical structure of the surfactant head and tail is essential in determining the overall performance properties of a surfactant in aqueous media. The surfactant tail drives the self-assembly process through the hydrophobic effect, while the surfactant head imparts a certain extent of solubility to the surfactant in aqueous solution through preferential interactions with the hydrogen-bonding network of water. The interplay between these two effects gives rise to the particular phase diagram of a surfactant, including the specific cmc at which micelles begin to form. In addition to serving as a quantitative indicator of micelle formation, the cmc represents a limit to surface monolayer formation, and hence to surface and interfacial tension reduction, because surfactant adsorption at interfaces remains approximately constant beyond the cmc. In addition, the cmc represents the onset of changes in bulk solution properties. This Thesis is concerned with the prediction of cmc

  18. The interactions between ionic surfactants and phosphatidylcholine vesicles: Conductometry

    Science.gov (United States)

    Tsao, Heng-Kwong; Tseng, Wen Liang

    2001-11-01

    The interaction between ionic surfactants and phosphatidylcholine vesicles, which are prepared without addition of buffer and salt, is investigated by conductivity measurements. On the basis of the vesicle acting as a trap of charge carriers, the bilayer/aqueous phase partition coefficient K and the surfactant/lipid molar ratio Re of nine surfactants are determined. The thermodynamic consistency is satisfied by the measured parameters. The effects of the alkyl chain length (C10-C16) and ionic head group are then studied. The inverse partition coefficient K-1 is linearly related to the critical micelle concentration. The solubilizing ability Reb is a consequence of the competition between the surfactant incorporation into the bilayer and the formation of micelles. Consequently, the K parameter rises whereas the Reb parameter declines as the chain length is increased. The influence due to addition of salt is also discussed.

  19. Liquid-liquid extraction by reversed micelles in biotechnological processes

    Directory of Open Access Journals (Sweden)

    Kilikian B. V.

    2000-01-01

    Full Text Available In biotechnology there is a need for new purification and concentration processes for biologically active compounds such as proteins, enzymes, nucleic acids, or cells that combine a high selectivity and biocompatibility with an easy scale-up. A liquid-liquid extraction with a reversed micellar phase might serve these purposes owing to its capacity to solubilize specific biomolecules from dilute aqueous solutions such as fermentation and cell culture media. Reversed micelles are aggregates of surfactant molecules containing an inner core of water molecules, dispersed in a continuous organic solvent medium. These reversed micelles are capable of selectively solubilizing polar compounds in an apolar solvent. This review gives an overview of liquid-liquid extraction by reversed micelles for a better understanding of this process.

  20. Modification of encapsulation pressure of reverse micelles in liquid ethane.

    Science.gov (United States)

    Peterson, Ronald W; Nucci, Nathaniel V; Wand, A Joshua

    2011-09-01

    Encapsulation within reverse micelles dissolved in low viscosity fluids offers a potential solution to the slow tumbling problem presented by large soluble macromolecules to solution NMR spectroscopy. The reduction in effective macromolecular tumbling is directly dependent upon the viscosity of the solvent. Liquid ethane is of sufficiently low viscosity at pressures below 5000 psi to offer a significant advantage. Unfortunately, the viscosity of liquid ethane shows appreciable pressure dependence. Reverse micelle encapsulation in liquid ethane often requires significantly higher pressures, which obviates the potential advantages offered by liquid ethane over liquid propane. Addition of co-surfactants or co-solvents can be used to manipulate the minimum pressure required to obtain stable, well-behaved solutions of reverse micelles prepared in liquid ethane. A library of potential additives is examined and several candidates suitable for use with encapsulated proteins are described. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Near-Infrared Squaraine Dye Encapsulated Micelles for in Vivo Fluorescence and Photoacoustic Bimodal Imaging.

    Science.gov (United States)

    Sreejith, Sivaramapanicker; Joseph, James; Lin, Manjing; Menon, Nishanth Venugopal; Borah, Parijat; Ng, Hao Jun; Loong, Yun Xian; Kang, Yuejun; Yu, Sidney Wing-Kwong; Zhao, Yanli

    2015-06-23

    Combined near-infrared (NIR) fluorescence and photoacoustic imaging techniques present promising capabilities for noninvasive visualization of biological structures. Development of bimodal noninvasive optical imaging approaches by combining NIR fluorescence and photoacoustic tomography demands suitable NIR-active exogenous contrast agents. If the aggregation and photobleaching are prevented, squaraine dyes are ideal candidates for fluorescence and photoacoustic imaging. Herein, we report rational selection, preparation, and micelle encapsulation of an NIR-absorbing squaraine dye (D1) for in vivo fluorescence and photoacoustic bimodal imaging. D1 was encapsulated inside micelles constructed from a biocompatible nonionic surfactant (Pluoronic F-127) to obtain D1-encapsulated micelles (D1(micelle)) in aqueous conditions. The micelle encapsulation retains both the photophysical features and chemical stability of D1. D1(micelle) exhibits high photostability and low cytotoxicity in biological conditions. Unique properties of D1(micelle) in the NIR window of 800-900 nm enable the development of a squaraine-based exogenous contrast agent for fluorescence and photoacoustic bimodal imaging above 820 nm. In vivo imaging using D1(micelle), as demonstrated by fluorescence and photoacoustic tomography experiments in live mice, shows contrast-enhanced deep tissue imaging capability. The usage of D1(micelle) proven by preclinical experiments in rodents reveals its excellent applicability for NIR fluorescence and photoacoustic bimodal imaging.

  2. Effects of Surfactants on the Rate of Chemical Reactions

    Directory of Open Access Journals (Sweden)

    B. Samiey

    2014-01-01

    Full Text Available Surfactants are self-assembled compounds that depend on their structure and electric charge can interact as monomer or micelle with other compounds (substrates. These interactions which may catalyze or inhibit the reaction rates are studied with pseudophase, cooperativity, and stoichiometric (classical models. In this review, we discuss applying these models to study surfactant-substrate interactions and their effects on Diels-Alder, redox, photochemical, decomposition, enzymatic, isomerization, ligand exchange, radical, and nucleophilic reactions.

  3. Coupled Organoclay/Micelle Action for the Adsorption of Diclofenac.

    Science.gov (United States)

    De Oliveira, Tiago; Guégan, Régis

    2016-09-20

    A Na-smectite clay mineral (Na-Mt) was exchanged with various amounts of benzyldimethyltetradecyl ammonium chloride cationic surfactant (BDTAC) up to four times the cation exchange capacity (CEC). The adsorption properties of these organoclays as well as a coupled micelle/organoclay process were evaluated to remove an anionic pharmaceutical product, the diclofenac (DCF), recognized as a recalcitrant compound for conventional water treatments and to be poorly adsorbed onto untreated clay mineral. The DCF affinity appears to depend on the lipophilic character of organoclays in correlation to the density of intercalated BDTA and is particularly enhanced for sorbent systems with free surfactant or micelle in solution. The combination of both organclay and BDTA in excess or micelle as a one pot adsorption system appears to be the most efficient material for the sequestration of DCF and other pharmaceutical products (PPs) with a KF Freundlich constant of 1.7 L g(-1) and no restriction of the adsorbed DCF amount as the linear adsorption isotherm shows. A BDTA hydrophobic core micelle coupled with a positive electric charge forms an organic complex with DCF that is properly intercalated within the interlayer space of BDTA-Mt organoclays as both Fourier transform infrared (FTIR) and X-ray diffraction (XRD) data supported.

  4. Molecular-thermodynamic theory of micellization of pH-sensitive surfactants.

    Science.gov (United States)

    Goldsipe, Arthur; Blankschtein, Daniel

    2006-04-11

    A predictive, molecular-thermodynamic theory is developed to model the micellization of pH-sensitive surfactants. The theory combines a molecular-thermodynamic description of micellization in binary surfactant mixtures with the protonation equilibrium of the surfactant monomers. The thermodynamic component of the theory models the pH-mediated equilibrium between micelles, surfactant monomers, and counterions. These counterions may originate from the surfactant or from added salt, acid, or base. The molecular component of the theory models the various contributions to the free energy of micellization, which corresponds to the free-energy change associated with forming a mixed micelle from the protonated and deprotonated forms of the surfactant and from the bound counterions. The free energy of micellization includes hydrophobic, interfacial, packing, steric, electrostatic, and entropic contributions, which are all calculated molecularly. The theory also requires knowledge of the surfactant molecular structure and the solution conditions, including the temperature and the amount of any added salt, acid, or base. To account for the pH sensitivity of the surfactant, the theory requires knowledge of the surfactant monomer equilibrium deprotonation constant (pK1), which may be obtained from experimental titration data obtained below the critical micelle concentration (cmc). The theory can be utilized to predict the equilibrium micelle and solution properties, including the cmc, the micelle composition, the micelle shape and aggregation number, the solution pH, and the micelle deprotonation equilibrium constant (pKm). Theoretical predictions of the cmc, the micelle aggregation number, and the pKm compare favorably with the available experimental data for alkyldimethylamine oxide surfactants. This class of pH-sensitive surfactants exhibits a form of self-synergy, which has previously been attributed to hydrogen-bond formation at the micelle interface. Instead, we show that

  5. Effect of surfactant concentration on the evaporation of droplets on cotton (Gossypium hirsutum L.) leaves.

    Science.gov (United States)

    Zhou, Zhaolu; Cao, Chong; Cao, Lidong; Zheng, Li; Xu, Jun; Li, Fengmin; Huang, Qiliang

    2018-04-05

    The evaporation kinetics of pesticide droplets deposited on a leaf surface can affect their application efficiency. Evaporation of droplets on the hydrophobic leaves has received considerable attention, but little is known about hydrophilic leaf surfaces. In this study, the effect of surfactant concentration on the evaporation of droplets deposited on cotton leaves was investigated. The evaporation time is roughly decreased for concentrations ranging from 0% to 0.01% and increased from 0.01% to 0.10%. Contrary to the widely held belief that pesticide retention on target crops can rapidly be formed only with surfactant concentrations exceeding the CMC (critical micelle concentration), this study demonstrates that, on hydrophilic cotton leaves, fast evaporation of the droplet at surfactant concentrations of 0.01% (CMC) can reduce the volume quickly, lower the loss point and enhance pesticide retention. In addition, the evolution of droplet volume, height and contact angle on the cotton leaf surface were measured to confirm this conclusion. The result presented herein can be used to guide the use of surfactants and pesticides in agriculture. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Thermodynamic and Interfacial Properties of DTABr/CTABr Mixed Surfactant Systems in Ethanolamine/Water Mixtures: A Conductometry Study

    OpenAIRE

    Esan, Olaseni Segun; Osundiya, Medinat Olubunmi; Aboluwoye, Christopher Olumuyiwa; Olanrewaju, Owoyomi; Ige, Jide

    2013-01-01

    Mixed-micelle formation in the binary mixtures of dodecyltrimethylammonium bromide (DTABr) and cetyltrimethylammonium bromide (CTABr) surfactants in water-ethanolamine mixed solvent systems has been studied by conductometric method in the temperature range of 298.1 to 313.1 K at 5 K intervals. It was observed that the presence of ethanolamine forced the formation of mixed micelle to lower total surfactant concentration than in water only. The synergistic interaction was quantitatively investi...

  7. NMR study of the dynamics of cationic gemini surfactant 14-2-14 in mixed solutions with conventional surfactants.

    Science.gov (United States)

    Jiang, Yan; Lu, Xing-Yu; Chen, Hong; Mao, Shi-Zhen; Liu, Mai-Li; Luo, Ping-Ya; Du, You-Ru

    2009-06-18

    Three kinds of conventional surfactants, namely, two nonionic surfactants [polyethylene glycol (23) lauryl ether (Brij-35) and Triton X-100 (TX-100)], one cationic surfactant [n-tetradecyltrimethyl ammonium bromide (TTAB)], and an anionic surfactant [sodium n-dodecyl sulfate (SDS)}, were mixed into the quaternary ammonium gemini surfactant [C(14)H(29)N(+)(CH(3))(2)](2)(CH(2))(2).2Br(-) (14-2-14) in aqueous solution. The exchange rate constants between 14-2-14 molecules in the mixed micelles and those in the bulk solution were detected using two nuclear magnetic resonance (NMR) methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). The results obtained from these two methods were consistent. Both showed that mixing a nonionic conventional surfactant, either Brij-35 or TX-100, enhanced the exchange process between the 14-2-14 molecules in the mixed micelles and those in the bulk solution. In contrast, the anionic surfactant SDS and the cationic surfactant TTAB slowed the process slightly.

  8. Synthesis and properties evaluation of sulfobetaine surfactant with double hydroxyl

    Science.gov (United States)

    Zhou, Ming; Luo, Gang; Zhang, Ze; Li, Sisi; Wang, Chengwen

    2017-09-01

    A series of sulfobetaine surfactants {N-[(3-alkoxy-2-hydroxyl)propoxy] ethyl-N,N-dimethyl-N-(2-hydroxyl)propyl sulfonate} ammonium chloride were synthesized with raw materials containing linear saturated alcohol, N,N-dimethylethanolamine, sodium 3-chloro-2-hydroxyl propane sulfonic acid and epichlorohydrin. The molecule structures of sulfobetaine surfactants were characterized by FTIR, 1HNMR and elemental analysis. Surface tension measurements can provide us information about the surface tension at the CMC (γCMC), pC20, Γmax and Amin. The pC20 values of sulfobetaine surfactants increase with the hydrophobic chain length increasing. Amin values of the surfactants decrease with increasing hydrophobic chain length from 10 to 14. The critical micelle concentration (CMC) and surface tension (γCMC) values of the sulfobetaine surfactants decrease with increasing hydrophobic chain length from 10 to 16. The lipophilicity of surfactant was enhanced with the increase of the carbon chain, however, the ability of anti-hard water was weakened. The minimum oil/water interfacial tension of four kinds of sulfobetaine surfactants is 10-2-10-3 mN/m magnitude, which indicates that the synthesized bis-hydroxy sulfobetaine surfactants have a great ability to reduce interfacial tension in the surfactant flooding system. The surface tension (γCMC) values of synthesized surfactants were lower compared with conventional anionic surfactant sodium dodecyl sulfonate.

  9. Study of interactions between hyaluronan and cationic surfactants by means of calorimetry, turbidimetry, potentiometry and conductometry.

    Science.gov (United States)

    Krouská, J; Pekař, M; Klučáková, M; Šarac, B; Bešter-Rogač, M

    2017-02-10

    The thermodynamics of the micelle formation of the cationic surfactants tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB) with and without the addition of hyaluronan of two molecular weights was studied in aqueous solution by titration calorimetry. Macroscopic phase separation, which was detected by calorimetry and also by conductometry, occurs when charges on the surfactant and hyaluronan are balanced. In contrast, turbidimetry and potentiometry showed hyaluronan-surfactant interactions at very low surfactant concentrations. The observed differences between systems prepared with CTAB and TTAB indicate that besides the electrostatic interactions, which probably predominate, hydrophobic effects also play a significant role in hyaluronan interactions with cationic surfactants. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Small-angle neutron scattering studies of nonionic surfactant: Effect ...

    Indian Academy of Sciences (India)

    celle above a concentration called critical micelle concentration (CMC) where their properties are different from those of the ... It is well-known that SANS is an ideal technique to study the micellar structure of surfactants [8,9] and this has also ... ment at the Dhruva reactor, Mumbai [11]. The mean wavelength of the incident.

  11. (Cationic + nonionic) mixed surfactant aggregates for solubilisation of curcumin

    International Nuclear Information System (INIS)

    Kumar, Arun; Kaur, Gurpreet; Kansal, S.K.; Chaudhary, G.R.; Mehta, S.K.

    2016-01-01

    Highlights: • Critical micelle concentration of mixed surfactant has been measured. • Aqueous solubility and alkaline stability of curcumin has been significantly improved. • Location of curcumin within micelles has been evaluated. • Scavenging activity of curcumin has been improved. • Non-intercalative binding with ct-DNA has been observed. - Abstract: Curcumin is a potential drug for variety of diseases. Major limitations of curcumin are low water solubility, rapid hydrolytic degradation in alkaline medium and poor bioavailability. To overcome these limitations, highly potential mixed micellar system has been prepared. In order to reduce inter ionic repulsion and precipitation of surfactants, (cationic + non-ionic) mixed system have been chosen that directly influence its applicability. Hydrophobic chain of non-ionic surfactant significantly influences the cmc of mixed surfactant system as indicated by fluorescence and conductivity data. UV–visible spectroscopy analyses show that solubility, stability and antioxidant property of the curcumin is remarkably improved depending on cmc and aggregation number (N_a_g_g) of mixed surfactants, where N_a_g_g plays crucial role. Generally, curcumin undergoes complete degradation in slight basic medium, but stability has been maintained up to 8 h at pH-13 using formulated mixed micelles (only (20 to 25)% degraded). Location of curcumin which is monitored using emission spectroscopy, fluorescence quenching and "1H NMR spectroscopy techniques play the most important role. Observed results show that the major population of curcumin is located at the polar region and some are in hydrophobic region of the mixed micelles. To ensure the effect of mixed surfactants and curcumin loaded mixed surfactants on DNA, the interaction parameter indicates non-interclative interactions.

  12. Method for the preparation of metal colloids in inverse micelles and product preferred by the method

    Science.gov (United States)

    Wilcoxon, Jess P.

    1992-01-01

    A method is provided for preparing catalytic elemental metal colloidal particles (e.g. gold, palladium, silver, rhodium, iridium, nickel, iron, platinum, molybdenum) or colloidal alloy particles (silver/iridium or platinum/gold). A homogeneous inverse micelle solution of a metal salt is first formed in a metal-salt solvent comprised of a surfactant (e.g. a nonionic or cationic surfactant) and an organic solvent. The size and number of inverse micelles is controlled by the proportions of the surfactant and the solvent. Then, the metal salt is reduced (by chemical reduction or by a pulsed or continuous wave UV laser) to colloidal particles of elemental metal. After their formation, the colloidal metal particles can be stabilized by reaction with materials that permanently add surface stabilizing groups to the surface of the colloidal metal particles. The sizes of the colloidal elemental metal particles and their size distribution is determined by the size and number of the inverse micelles. A second salt can be added with further reduction to form the colloidal alloy particles. After the colloidal elemental metal particles are formed, the homogeneous solution distributes to two phases, one phase rich in colloidal elemental metal particles and the other phase rich in surfactant. The colloidal elemental metal particles from one phase can be dried to form a powder useful as a catalyst. Surfactant can be recovered and recycled from the phase rich in surfactant.

  13. Building a Better Microreactor: Enzyme Catalysis in AOT/Bile Salt Reversed Micelles

    National Research Council Canada - National Science Library

    McGown, Linda

    2001-01-01

    .... We have shown that trihydroxy bile salts modify the interfacial properties of AOT reversed micelles, thereby affecting the reversed micellar structure, the biological activity of entrapped enzymes...

  14. Improving anticancer activity and reducing systemic toxicity of doxorubicin by self-assembled polymeric micelles

    International Nuclear Information System (INIS)

    Gou Maling; Shi Huashan; Guo Gang; Men Ke; Zhang Juan; Li Zhiyong; Luo Feng; Qian Zhiyong; Wei Yuquan; Zheng Lan; Zhao Xia

    2011-01-01

    In an attempt to improve anticancer activity and reduce systemic toxicity of doxorubicin (Dox), we encapsulated Dox in monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelles by a novel self-assembly procedure without using surfactants, organic solvents or vigorous stirring. These Dox encapsulated MPEG-PCL (Dox/MPEG-PCL) micelles with drug loading of 4.2% were monodisperse and ∼ 20 nm in diameter. The Dox can be released from the Dox/MPEG-PCL micelles; the Dox-release at pH 5.5 was faster than that at pH 7.0. Encapsulation of Dox in MPEG-PCL micelles enhanced the cellular uptake and cytotoxicity of Dox on the C-26 colon carcinoma cell in vitro, and slowed the extravasation of Dox in the transgenic zebrafish model. Compared to free Dox, Dox/MPEG-PCL micelles were more effective in inhibiting tumor growth in the subcutaneous C-26 colon carcinoma and Lewis lung carcinoma models, and prolonging survival of mice bearing these tumors. Dox/MPEG-PCL micelles also induced lower systemic toxicity than free Dox. In conclusion, incorporation of Dox in MPEG-PCL micelles enhanced the anticancer activity and decreased the systemic toxicity of Dox; these Dox/MPEG-PCL micelles are an interesting formulation of Dox and may have potential clinical applications in cancer therapy.

  15. Improving anticancer activity and reducing systemic toxicity of doxorubicin by self-assembled polymeric micelles

    Energy Technology Data Exchange (ETDEWEB)

    Gou Maling; Shi Huashan; Guo Gang; Men Ke; Zhang Juan; Li Zhiyong; Luo Feng; Qian Zhiyong; Wei Yuquan [State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu 610041 (China); Zheng Lan; Zhao Xia, E-mail: anderson-qian@163.com [West China Second University Hospital, West China Women' s and Children' s Hospital, Sichuan University, Chengdu 610041 (China)

    2011-03-04

    In an attempt to improve anticancer activity and reduce systemic toxicity of doxorubicin (Dox), we encapsulated Dox in monomethoxy poly(ethylene glycol)-poly({epsilon}-caprolactone) (MPEG-PCL) micelles by a novel self-assembly procedure without using surfactants, organic solvents or vigorous stirring. These Dox encapsulated MPEG-PCL (Dox/MPEG-PCL) micelles with drug loading of 4.2% were monodisperse and {approx} 20 nm in diameter. The Dox can be released from the Dox/MPEG-PCL micelles; the Dox-release at pH 5.5 was faster than that at pH 7.0. Encapsulation of Dox in MPEG-PCL micelles enhanced the cellular uptake and cytotoxicity of Dox on the C-26 colon carcinoma cell in vitro, and slowed the extravasation of Dox in the transgenic zebrafish model. Compared to free Dox, Dox/MPEG-PCL micelles were more effective in inhibiting tumor growth in the subcutaneous C-26 colon carcinoma and Lewis lung carcinoma models, and prolonging survival of mice bearing these tumors. Dox/MPEG-PCL micelles also induced lower systemic toxicity than free Dox. In conclusion, incorporation of Dox in MPEG-PCL micelles enhanced the anticancer activity and decreased the systemic toxicity of Dox; these Dox/MPEG-PCL micelles are an interesting formulation of Dox and may have potential clinical applications in cancer therapy.

  16. Controlling block copolymer phase behavior using ionic surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Ray, D.; Aswal, V. K. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India E-mail: debes.phys@gmail.com (India)

    2016-05-23

    The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO{sub 26}PO{sub 39}EO{sub 26})] in presence of anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution as a function of temperature has been studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactants. Each of the individual components (block copolymer and surfactant) and the nanoparticle–surfactant mixed system have been examined at varying temperature. The block copolymer P85 forms spherical micelles at room temperature whereas shows sphere-to-rod like micelle transition at higher temperatures. On the other hand, SDS surfactant forms ellipsoidal micelles over a wide temperature range. Interestingly, it is found that phase behavior of mixed micellar system (P85 + SDS) as a function of temperature is drastically different from that of P85, giving the control over the temperature-dependent phase behavior of block copolymers.

  17. Weak and saturable protein-surfactant interactions in the denaturation of apo-alpha-lactalbumin by acidic and lactonic sophorolipid

    Directory of Open Access Journals (Sweden)

    Kell K Andersen

    2016-11-01

    Full Text Available Biosurfactants are of growing interest as sustainable alternatives to fossil-fuel-derived chemical surfactants, particularly for the detergent industry. To realize this potential, it is necessary to understand how they affect proteins which they may encounter in their applications. However knowledge of such interactions is limited. Here we present a study of the interactions between the model protein apo-alpha-lactalbumin and the biosurfactant sophorolipid (SL produced by the yeast Starmerella bombicola. SL occurs both as an acidic and a lactonic form; the lactonic form (lactSL is sparingly soluble and has a lower critical micelle concentration than the acidic form (acidSL. We show that acidSL affects apo-aLA in a similar way to the related glycolipid biosurfactant rhamnolipid (RL, with the important difference that RL is also active below the cmc in contrast to acidSL. Using isothermal titration calorimetry data, we show that acidSL has weak and saturable interactions with apo-aLA at low concentrations; due to the relatively low cmc of acidSL (which means that the monomer concentration is limited to ca. 0-1 mM SL, it is only possible to observe interactions with monomeric acidSL at high apo-aLA concentrations. However, the denaturation kinetics of apo-aLA in the presence of acidSL are consistent with a collaboration between monomeric and micellar surfactant species, similar to RL and nonionic or zwitterionic surfactants. Inclusion of lactSL as mixed micelles with acidSL lowers the cmc and this effectively reduces the rate of unfolding, emphasizing that SL like other biosurfactants is a gentle anionic surfactant. Our data highlight the potential of these biosurfactants for future use in the detergent industry.

  18. Probing dynamics and mechanism of exchange process of quaternary ammonium dimeric surfactants, 14-s-14, in the presence of conventional surfactants.

    Science.gov (United States)

    Liu, Jun; Jiang, Yan; Chen, Hong; Mao, Shi Zhen; Du, You Ru; Liu, Mai Li

    2012-12-27

    In this Article, we investigated effects of different types of conventional surfactants on exchange dynamics of quaternary ammonium dimeric surfactants, with chemical formula C(14)H(29)N(+)(CH(3))(2)- (CH(2))(s)-N(+)(CH(3))(2)C(14)H(29)·2Br(-), or 14-s-14 for short. Two nonionic surfactants, TritonX-100 (TX-100) and polyethylene glycol (23) laurylether (Brij-35), and one cationic surfactant, n-tetradecyltrimethyl ammonium bromide (TTAB), and one ionic surfactant, sodium dodecyl sulfate (SDS) were chosen as typical conventional surfactants. Exchange rates of 14-s-14 (s = 2, 3, and 4) between the micelle form and monomer in solution were detected by two NMR methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). Results show that the nonionic surfactants (TX-100 and Brij-35), the cationic surfactant (TTAB), and the ionic surfactant (SDS) respectively accelerated, barely influenced, and slowed the exchange rate of 14-s-14. The effect mechanism was investigated by the self-diffusion experiment, relaxation time measurements (T(2)/T(1)), the fluorescence experiment (I(1)/I(3)) and observed chemical shift variations. Results reveal that, nonionic conventional surfactants (TX-100 and Brij-35) loosened the molecule arrangement and decreased hydrophobic interactions in the micelle, and thus accelerated the exchange rate of 14-s-14. The cationic conventional surfactant (TTAB) barely changed the molecule arrangement and thus barely influenced the exchange rate of 14-s-14. The ionic conventional surfactant (SDS) introduced the electrostatic attraction effect, tightened the molecule arrangement, and increased hydrophobic interactions in the micelle, and thus slowed down the exchange rate of 14-s-14. Additionally, the two-step exchange mechanism of 14-s-14 in the mixed solution was revealed through interesting variation tendencies of exchange rates of 14-s-14.

  19. Structural investigation of diglycerol monolaurate reverse micelles in nonpolar oils cyclohexane and octane

    International Nuclear Information System (INIS)

    Shrestha, Lok Kumar; Aramaki, Kenji

    2009-01-01

    Structure of diglycerol monolaurate (abbreviated as C 12 G 2 ) micelles in nonpolar oils cyclohexane and n-octane as a function of compositions, temperatures, and surfactant chain length has been investigated by small-angle X-ray scattering (SAXS). The SAXS data were evaluated by the generalized indirect Fourier transformation (GIFT) method and real-space structural information of particles was achieved. Conventional poly(oxyethylene) type nonionic surfactants do not form reverse micelles in oils unless a trace water is added. However, present surfactant C 12 G 2 formed reverse micelle (RM) in cyclohexane and n-octane without addition of water at normal room temperature. A clear signature of one dimensional (1-D) micellar growth was found with increasing C 12 G 2 concentration. On the other hand, increasing temperature or hydrocarbon chain length of surfactant shorten the length of RM, which is essentially a cylinder-to-sphere type transition in the aggregate structure. Drastic changes in the structure of RM, namely, transition of ellipsoidal prolate to long rod-like micelles was observed upon changing oil from cyclohexane to octane. All the microstructural transitions were explained in terms of critical packing parameter. (author)

  20. Titration calorimetry of surfactant–drug interactions: Micelle formation and saturation studies

    International Nuclear Information System (INIS)

    Waters, Laura J.; Hussain, Talib; Parkes, Gareth M.B.

    2012-01-01

    Highlights: ► Isothermal titration calorimetry can be used to monitor the saturation of micelles with pharmaceutical compounds. ► The number of drug molecules per micelle varies depending on the drug used and the temperature of the calorimeter. ► The change in enthalpy for the saturation of micelles with drugs can be endothermic or exothermic. ► The critical micellar concentration of an anionic surfactant (SDS) does not appear to vary in the presence of drugs. - Abstract: Isothermal titration calorimetry (ITC) was employed to monitor the addition of five model drugs to anionic surfactant based micelles, composed of sodium dodecyl sulfate (SDS), through to the point at which they were saturated with drug. Analysis of the resultant data using this newly developed method has confirmed the suitability of the technique to acquire such data with saturation limits established in all cases. Values for the point at which saturation occurred ranged from 17 molecules of theophylline per micelle at T = 298 K up to 63 molecules of caffeine per micelle at 310 K. Micellar systems can be disrupted by the presence of additional chemicals, such as the drugs used in this study, therefore a separate investigation was undertaken to determine the critical micellar concentration (CMC) for SDS in the presence of each drug at T = 298 K and 310 K using ITC. In the majority of cases, there was no appreciable alteration to the CMC of SDS with drug present.

  1. Influence of succinylation on physicochemical property of yak casein micelles.

    Science.gov (United States)

    Yang, Min; Yang, Jitao; Zhang, Yuan; Zhang, Weibing

    2016-01-01

    Succinylation is a chemical-modification method that affects the physicochemical characteristics and functional properties of proteins. This study assessed the influence of succinylation on the physicochemical properties of yak casein micelles. The results revealed that surface hydrophobicity indices decreased with succinylation. Additionally, denaturation temperature and denaturation enthalpy decreased with increasing succinylation level, except at 82%. The buffering properties of yak casein micelles were affected by succinylation. It was found that chemical modification contributed to a slight shift of the buffering peak towards a lower pH value and a markedly increase of the maximum buffering values of yak casein micelles at pH 4.5-6.0 and pH casein micellar hydration and whiteness values. The findings obtained from this study will provide the basic information on the physicochemical properties of native and succinylated yak casein micelles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Effects of gamma radiation on phase behaviour and critical micelle concentration of Triton X-100 aqueous solutions

    International Nuclear Information System (INIS)

    Valdes Diaz, G.; Rodriguez-Calvo, S.; Perez-Gramatges, A.; Rapado-Paneque, M.; Fernandez-Lima, F. A.; Ponciano, C. R.; Silveira, E. F. . E-mail. apgram@instec.cu

    2007-01-01

    Ionising radiation used for sterilisation can have an effect on the physico-chemical properties of pharmaceutically relevant excipient systems, affecting therefore the stability of the formulation. The effect of gamma irradiation on the phase behaviour (cloud point - CP) and critical micelle concentration (CMC) of aqueous solutions of Triton X-100, used as a model nonionic surfactant, is investigated in this paper. Micellar solutions irradiated with ?-rays in a dose range between 0 and 70 kGy, including the sterilisation range of pharmaceutical preparations, were analysed using mass spectrometry. Results show a slight shift in molecular mass distribution of ethoxylated surfactant, which indicates degradation of polyethoxylated chains by water radical attacks. This fact, combined with the formation of cross-linked species, is considered to be responsible for the decrease observed in CP and CMC values of micellar solutions at all absorbed doses. There is no spectroscopic evidence of radiation damage to aromatic ring or hydrocarbon tail of surfactant. Models based on Flory-Huggins theory were employed to estimate CP from changes in mass distribution and to obtain cross-linking fractions. (Author)

  3. Novel Pyridinium Surfactants with Unsaturated Alkyl Chains : Aggregation Behavior and Interactions with Methyl Orange in Aqueous Solution

    NARCIS (Netherlands)

    Kuiper, Johanna M.; Buwalda, Rixt T.; Hulst, Ron; Engberts, Jan B.F.N.

    2001-01-01

    This paper presents the synthesis and a study of the aggregation behavior of 4-undecyl-1-methyl- and 4-undecenyl-1-methylpyridinium iodide surfactants. The effect of the position of the double bond in the alkyl chain of the surfactant on the critical micelle concentration (cmc), degree of counterion

  4. Negative adsorption due to electrostatic exclusion of micelles.

    Science.gov (United States)

    Somasundaran, P; Ananthapadmanabhan, K P; Deo, Puspendu

    2005-10-15

    Interactions of surfactants with solid substrates are important in the controlling of processes such as flotation, coating, flocculation and sedimentation. These interactions usually lead to adsorption on solids, but can also result in an exclusion of the reagents with dire consequences. In this work electrostatic exclusion of negatively charged dodecylbenzene sulfonate micelles from quartz/water, Bio-Sil/water and alumina/water interfaces has been investigated as a function of pH and ionic strength. Measurable negative adsorption of these surfactants from similarly charged solid/liquid interface was observed in the micellar region. In the case of porous samples with large surface area, comparison of pore size with the micelle size is necessary to avoid any erroneous conclusions regarding the role of electrostatic exclusion in a given system. A theoretical model for the electrostatic exclusion of micelles is developed and used to calculate the adsorption of negatively charged dodecylbenzene sulfonate on negatively charged quartz (pH 7), silica (Bio-Sil A, pH 3) and alumina (pH 11) in the micellar concentration region. The micellar exclusion values calculated using the model are in excellent agreement with the experimental results.

  5. Use of surfactants for the remediation of contaminated soils: a review.

    Science.gov (United States)

    Mao, Xuhui; Jiang, Rui; Xiao, Wei; Yu, Jiaguo

    2015-03-21

    Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Enhanced hydrogen production by coupled system of Halobacterium halobium and chloroplast after entrapment within reverse micelles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, A.; Dubey, R.S. [Banaras Hindhu University, Varanasi (India). Dept. of Biochemistry; Pandey, K.D. [Banaras Hindhu University, Varanasi (India). Dept. of Botany

    1999-08-01

    Reverse micelles were used for the enhanced rate of photoproduction of hydrogen using the coupled system of Halobacterium halobium and chloroplasts organelles. Different combinations of organic solvents and surfactants were used for generating reverse micelles. A several fold enhancement in the rate of H{sub 2} production was observed when the coupled system was entrapped within reverse micelles as compared to the aqueous suspension where no detectable H{sub 2} was produced. The coupled system immobilized in reverse micelles formed by sodium lauryl sulfate and carbon tetrachloride yielded maximum rate of H{sub 2} evolution. The optimum temperature for such hydrogen production was 40{sup o}C using light of 520-570 nm wavelength and 100 lux intensity. (author)

  7. Synthesis and characterization of Fe colloid catalysts in inverse micelle solutions

    Energy Technology Data Exchange (ETDEWEB)

    Martino, A.; Stoker, M.; Hicks, M. [Sandia National Lab., Alburquerque, NM (United States)] [and others

    1995-12-31

    Surfactant molecules, possessing a hydrophilic head group and a hydrophobic tail group, aggregate in various solvents to form structured solutions. In two component mixtures of surfactant and organic solvents (e.g., toluene and alkanes), surfactants aggregate to form inverse micelles. Here, the hydrophilic head groups shield themselves by forming a polar core, and the hydrophobic tails groups are free to move about in the surrounding oleic phase. The formation of Fe clusters in inverse miscelles was studied.Iron salts are solubilized within the polar interior of inverse micelles, and the addition of the reducing agent LiBH{sub 4} initiates a chemical reduction to produce monodisperse, nanometer sized Fe based particles. The reaction sequence is sustained by material exchange between inverse micelles. The surfactant interface provides a spatial constraint on the reaction volume, and reactions carried out in these micro-heterogeneous solutions produce colloidal sized particles (10-100{Angstrom}) stabilized in solution against flocculation of surfactant. The clusters were stabilized with respect to size with transmission electron microscopy (TEM) and with respect to chemical composition with Mossbauer spectroscopy, electron diffraction, and x-ray photoelectron spectroscopy (XPS). In addition, these iron based clusters were tested for catalytic activity in a model hydrogenolysis reaction. The hydrogenolysis of naphthyl bibenzyl methane was used as a model for coal pyrolysis.

  8. Reactivity in inverse micelles

    International Nuclear Information System (INIS)

    Brochette, Pascal

    1987-01-01

    This research thesis reports the study of the use of micro-emulsions of water in oil as reaction support. Only the 'inverse micelles' domain of the ternary mixing (water/AOT/isooctane) has been studied. The main addressed issues have been: the micro-emulsion disturbance in presence of reactants, the determination of reactant distribution and the resulting kinetic theory, the effect of the interface on electron transfer reactions, and finally protein solubilization [fr

  9. Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants

    Directory of Open Access Journals (Sweden)

    Roza Bouchal

    2016-02-01

    Full Text Available Surface activity and micelle formation of alkylguanidinium chlorides containing 10, 12, 14 and 16 carbon atoms in the hydrophobic tail were studied by combining conductivity and surface tension measurements with isothermal titration calorimetry. The purity of the resulting surfactants, their temperatures of Cr→LC and LC→I transitions, as well as their propensity of forming birefringent phases, were assessed based on the results of 1H and 13C NMR, differential scanning calorimetry (DSC, and polarizing microscopy studies. Whenever possible, the resulting values of Krafft temperature (TK, critical micelle concentration (CMC, minimum surface tension above the CMC, chloride counter-ion binding to the micelle, and the standard enthalpy of micelle formation per mole of surfactant (ΔmicH° were compared to those characterizing alkyltrimethylammonium chlorides or bromides with the same tail lengths. The value of TK ranged between 292 and 314 K and increased strongly with the increase in the chain length of the hydrophobic tail. Micellization was described as both entropy and enthalpy-driven. Based on the direct calorimetry measurements, the general trends in the CMC with the temperature, hydrophobic tail length, and NaCl addition were found to be similar to those of other types of cationic surfactants. The particularly exothermic character of micellization was ascribed to the hydrogen-binding capacity of the guanidinium head-group.

  10. Influence of gold nanoparticles of varying size in improving the lipase activity within cationic reverse micelles.

    Science.gov (United States)

    Maiti, Subhabrata; Das, Dibyendu; Shome, Anshupriya; Das, Prasanta Kumar

    2010-02-08

    Herein, we report the effect of gold nanoparticles (GNPs) in enhancing lipase activity in reverse micelles of cetyltrimethylammonium bromide (CTAB)/water/isooctane/n-hexanol. The size and concentration of the nanoparticles were varied and their specific roles were assessed in detail. An overall enhancement of activity was observed in the GNP-doped CTAB reverse micelles. The improvement in activity becomes more prominent with increasing concentration and size of the GNPs (0-52 microM and ca. 3-30 nm, respectively). The observed highest lipase activity (k(2)=1070+/-12 cm(3) g(-1) s(-1)) in GNP-doped CTAB reverse micelles ([GNP]: 52 microm, ca. 20 nm) is 2.5-fold higher than in CTAB reverse micelles without GNPs. Improvement in the lipase activity is only specific to the GNP-doped reverse micellar media, whereas GNP deactivates and structurally deforms the enzyme in aqueous media. The reason for this activation is probably due to the formation of larger-sized reverse micelles in which the GNP acts as a polar core and the surfactants aggregate around the nanoparticle ('GNP pool') instead of only water. Lipase at the augmented interface of the GNP-doped reverse micelle showed improved activity because of enhancement in both the substrate and enzyme concentrations and increased flexibility in the lipase conformation. The extent of the activation is greater in the case of the larger-sized GNPs. A correlation has been established between the activity of lipase and its secondary structure by using circular dichroism and FTIR spectroscopic analysis. The generalized influence of GNP is verified in the reverse micelles of another surfactant, namely, cetyltripropylammonium bromide (CTPAB). TEM, dynamic light scattering (DLS), and UV/Vis spectroscopic analysis were utilized to characterize the GNPs and the organized aggregates. For the first time, CTAB-based reverse micelles have been found to be an excellent host for lipase simply by doping with appropriately sized GNPs.

  11. Steady state and time-resolved fluorescence spectroscopy of quinine sulfate dication bound to sodium dodecylsulfate micelles: Fluorescent complex formation

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Sunita; Pant, Debi D., E-mail: ddpant@pilani.bits-pilani.ac.in

    2014-01-15

    Interaction of quinine sulfate dication (QSD) with anionic, sodium dodecylsulphate (SDS) surfactant has been studied at different premicellar, micellar and postmicellar concentrations in aqueous phase using steady state, time-resolved fluorescence and fluorescence anisotropy techniques. At premicellar concentrations of SDS, the decrease in absorbance, appearance of an extra fluorescence band at lower wavelengths and tri-exponential decay behavior of fluorescence, are attributed to complex formation between QSD molecules and surfactant monomers. At postmicellar concentrations the red shift in fluorescence spectrum, increase in quantum yield and increase in fluorescence lifetimes are attributed to incorporation of solute molecules to micelles. At lower concentrations of SDS, a large shift in fluorescence is observed on excitation at the red edge of absorption spectrum and this is explained in terms of distribution of ion pairs of different energies in the ground state and the observed fluorescence lifetime behavior corroborates with this model. The temporal fluorescence anisotropy decay of QSD in SDS micelles allowed determination of restriction on the motion of the fluorophore. All the different techniques used in this study reveal that the photophysics of QSD is very sensitive to the microenvironments of SDS micelles and QSD molecules reside at the water-micelle interface. -- Highlights: • Probe molecule is very sensitive to microenvironment of micelles. • Highly fluorescent ion-pair formation has been observed. • Modulated photophysics of probe molecule in micellar solutions has been observed. • Probe molecules strongly bind with micelles and reside at probe–micelle interface.

  12. Interactions between tea catechins and casein micelles and their impact on renneting functionality.

    Science.gov (United States)

    Haratifar, Sanaz; Corredig, Milena

    2014-01-15

    Many studies have shown that tea catechins bind to milk proteins. This research focused on the association of tea polyphenols with casein micelles, and the consequences of the interactions on the renneting behaviour of skim milk. It was hypothesized that epigallocatechin-gallate (EGCG), the main catechin present in green tea, forms complexes with the casein micelles and that the association modifies the processing functionality of casein micelles. The binding of EGCG to casein micelles was quantified using HPLC. The formation of catechin-casein micelles complexes affected the rennet induced gelation of milk, and the effect was concentration dependent. Both the primary as well as the secondary stage of gelation were affected. These experiments clearly identify the need for a better understanding of the effect of tea polyphenols on the processing functionality of casein micelles, before milk products can be used as an appropriate platform for delivery of bioactive compounds. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Micellar solubilization in strongly interacting binary surfactant systems. [Binary surfactant systems of: dodecyltrimethylammonium chloride + sodium dodecyl sulfate; benzyldimethyltetradecylammonium chloride + tetradecyltrimethylammonium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Treiner, C. (Universite Pierre et Marie Curie, Paris (France)); Nortz, M.; Vaution, C. (Faculte de Pharmacie de Paris-sud, Chatenay-Malabry (France))

    1990-07-01

    The apparent partition coefficient P of barbituric acids between micelles and water has been determined in mixed binary surfactant solutions from solubility measurements in the whole micellar composition range. The binary systems chosen ranged from the strongly interacting system dodecyltrimethylammonium chloride + sodium dodecyl sulfate to weakly interacting systems such as benzyldimethyltetradecylammonium chloride + tetradecyltrimethyammonium chloride. In all cases studied, mixed micelle formation is unfavorable to micellar solubilization. A correlation is found between the unlike surfactants interaction energy, as measured by the regular solution parameter {beta} and the solute partition coefficient change upon surfactant mixing. By use of literature data on micellar solubilization in binary surfactant solutions, it is shown that the change of P for solutes which are solubilized by surface adsorption is generally governed by the sign and amplitude of the interaction parameter {beta}.

  14. Magnetic surfactants as molecular based-magnets with spin glass-like properties

    International Nuclear Information System (INIS)

    Brown, Paul; Hatton, T Alan; Smith, Gregory N; Hernández, Eduardo Padrón; James, Craig; Eastoe, Julian; Nunes, Wallace C; Settens, Charles M; Baker, Peter J

    2016-01-01

    This paper reports the use of muon spin relaxation spectroscopy to study how the aggregation behavior of magnetic surfactants containing lanthanide counterions may be exploited to create spin glass-like materials. Surfactants provide a unique approach to building in randomness, frustration and competing interactions into magnetic materials without requiring a lattice of ordered magnetic species or intervening ligands and elements. We demonstrate that this magnetic behavior may also be manipulated via formation of micelles rather than simple dilution, as well as via design of surfactant molecular architecture. This somewhat unexpected result indicates the potential of using novel magnetic surfactants for the generation and tuning of molecular magnets. (paper)

  15. Capillary pressure across a pore throat in the presence of surfactants

    KAUST Repository

    Jang, Junbong

    2016-11-22

    Capillarity controls the distribution and transport of multiphase and immiscible fluids in soils and fractured rocks; therefore, capillarity affects the migration of nonaqueous contaminants and remediation strategies for both LNAPLs and DNAPLs, constrains gas and oil recovery, and regulates CO2 injection and geological storage. Surfactants alter interfacial tension and modify the invasion of pores by immiscible fluids. Experiments are conducted to explore the propagation of fluid interfaces along cylindrical capillary tubes and across pore constrictions in the presence of surfactants. Measured pressure signatures reflect the interaction between surface tension, contact angle, and the pore geometry. Various instabilities occur as the interface traverses the pore constriction, consequently, measured pressure signatures differ from theoretical trends predicted from geometry, lower capillary pressures are generated in advancing wetting fronts, and jumps are prone to under-sampling. Contact angle and instabilities are responsible for pronounced differences between pressure signatures recorded during advancing and receding tests. Pressure signatures gathered with surfactant solutions suggest changes in interfacial tension at the constriction; the transient surface tension is significantly lower than the value measured in quasi-static conditions. Interface stiffening is observed during receding fronts for solutions near the critical micelle concentration. Wetting liquids tend to form plugs at pore constrictions after the invasion of a nonwetting fluid; plugs split the nonwetting fluid into isolated globules and add resistance against fluid flow.

  16. Comprehensive study of tartrazine/cationic surfactant interaction.

    Science.gov (United States)

    Shahir, Afshin Asadzadeh; Javadian, Soheila; Razavizadeh, Bi Bi Marzieh; Gharibi, Hussein

    2011-12-15

    Interaction of a food dye, tartrazine, with some cationic conventional and gemini surfactants, tetradecyltrimethylammonium bromide (TTAB), N,N'-ditetradecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (14,4,14), and N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (12,4,12), were first investigated comprehensively employing conductometry, tensiometry, and UV-visible spectroscopy. Tartrazine was found to behave in the same manner as aromatic counterions. The formation of ion pairs reflected as a considerable increase of the surfactant efficiency in tensiometry plots and their stoichiometry were determined by Job's method of continuous variations. For the tartrazine/TTAB system, nonionic DS(3), ionic DS(2-), and/or DS(2)(-) ion pairs, their small premicelles, and tartrazine-rich micelles were constituted as well as dye-containing TTAB-rich micelles. Insoluble J-aggregates of DS(-) ion pairs and cylindrical surfactant-rich micelles were also formed in tartrazine/gemini surfactant systems and recognized by transmission electron microscopy. The zeta potential and the size of the aggregates were determined using dynamic light scattering and confirmed the suggested models for the processes happening in each system. Cyclic voltammetry was applied successfully to track all of these species using tartrazine's own reduction peak current for the first time.

  17. Lecithin in mixed micelles attenuates the cytotoxicity of bile salts in Caco-2 cells.

    Science.gov (United States)

    Tan, Ya'nan; Qi, Jianping; Lu, Yi; Hu, Fuqiang; Yin, Zongning; Wu, Wei

    2013-03-01

    This study was designed to investigate the cytotoxicity of bile salt-lecithin mixed micelles on the Caco-2 cell model. Cell viability and proliferation after mixed micelles treatments were evaluated with the MTT assay, and the integrity of Caco-2 cell monolayer was determined by quantitating the transepithelial electrical resistance and the flux of tracer, FITC-dextran 4400. The apoptosis induced by mixed micelles treatments was investigated with the annexin V/PI protocol. The particle size of mixed micelles was all smaller than 100 nm. The mixed micelles with lower than 0.2mM sodium deoxycholate (SDC) had no significant effects on cell viability and proliferation. When the level of SDC was higher than 0.4mM and the lecithin/SDC ratio was lower than 2:1, the mixed micelles caused significant changes in cell viability and proliferation. Furthermore, the mixed micelles affected tight junctions in a composition-dependent manner. Specifically, the tight junctions were transiently opened rather than damaged by the mixed micelles with SDC of between 0.2 and 0.6mM. The mixed micelles with more lecithin also induced less apoptosis. These results demonstrate that relatively higher concentrations of mixed micelles are toxic to Caco-2 cells, while phospholipids can attenuate the toxicity of the bile salts. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  18. Understanding thermodynamics of drug partitioning in micelles and delivery to proteins: Studies with naproxen, diclofenac sodium, tetradecyltrimethylammonium bromide, and bovine serum albumin

    International Nuclear Information System (INIS)

    Talele, Paurnima; Choudhary, Sinjan; Kishore, Nand

    2016-01-01

    Highlights: • Interactions of non-steroidal anti-inflammatory drugs studied with TTAB micelles, monomers. • Thermodynamics of drug-surfactant interactions and partitioning in micelles addressed. • Mechanism of drug partitioning addressed based on energetics of interactions. • Partitioning in micelles depends on functional groups on drugs. • Such studies are needed for target oriented synthesis and efficient drug delivery. - Abstract: The use of surfactants in drug delivery has offered several advantages. Quantitative knowledge of the interactions of drugs with micellar systems is essential for deriving guidelines to design efficient drug delivery systems. In this work we have quantitatively addressed the mechanism of interaction of naproxen and diclofenac sodium with the micelles and monomers of tetradecyltrimethylammonium bromide (TTAB) based on thermodynamic studies by using isothermal titration calorimetry. The mechanism of interaction of the drugs with TTAB is based on identification of the nature of interactions of the former with the surfactant micelles and monomers. The values of partitioning constant (which is same as equilibrium constant for the reaction of drugs with the surfactant micelles), enthalpy, entropy and stoichiometry of partitioning have been determined and discussed in terms of possible intermolecular interactions. Further, the interaction of the drug naproxen with bovine serum albumin, when delivered from the micellar media has also been addressed in terms of binding constant, enthalpy and entropy of binding. The results are important in developing improved strategies for effective drug delivery systems.

  19. Micelle swelling agent derived cavities for increasing hydrophobic organic compound removal efficiency by mesoporous micelle@silica hybrid materials

    KAUST Repository

    Shi, Yifeng

    2012-06-01

    Mesoporous micelle@silica hybrid materials with 2D hexagonal mesostructures were synthesized as reusable sorbents for hydrophobic organic compounds (HOCs) removal by a facile one-step aqueous solution synthesis using 3-(trimethoxysily)propyl-octadecyldimethyl-ammonium chloride (TPODAC) as a structure directing agent. The mesopores were generated by adding micelle swelling agent, 1,3,5-trimethyl benzene, during the synthesis and removing it afterward, which was demonstrated to greatly increase the HOC removal efficiency. In this material, TPODAC surfactant is directly anchored on the pore surface of mesoporous silica via SiOSi covalent bond after the synthesis due to its reactive Si(OCH 3) 3 head group, and thus makes the synthesized materials can be easily regenerated for reuse. The obtained materials show great potential in water treatment as pollutants sorbents. © 2011 Elsevier Inc. All rights reserved.

  20. Enzymatic reactions in reversed micelles

    NARCIS (Netherlands)

    Hilhorst, M.H.

    1984-01-01

    It has been recognised that enzymes in reversed micelles have potential for application in chemical synthesis. Before these expectations will be realised many problems must be overcome. This thesis deals with some of them.
    In Chapter 1 the present knowledge about reversed micelles and

  1. Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

    OpenAIRE

    Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

    2014-01-01

    Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each ...

  2. New thermo-sensitive chelating surfactants for selective solvent-free extraction of uranyl nitrate

    International Nuclear Information System (INIS)

    Prevost, S.; Larpent, C.; Testard, F.; Coulombeau, H.; Baczko, K.; Berthon, L.; Desvaux, H.; Madic, C.; Zemb, T.

    2004-01-01

    Functional surfactants were synthesised by grafting a chelating group (amino-acid residue) to the tip of a poly-ethoxylated nonionic surfactant chain (C i E j : C i H 2i +1(OCH 2 CH 2 ) j OH)) or in a branched position. C i E j nonionic surfactants are known to be thermo-reversible and to exhibit a clouding phenomenon associated to phase separation of micelles. The functional surfactants retain both surface-active properties, characteristic thermo-reversible behaviour and have efficient complexing properties toward uranyl. In the presence of uranyl nitrate, small micelles are formed at ambient temperature and the de-mixing leads to a separation of the target ion trapped by the functional surfactant (cloud point extraction). Those surfactants are more efficient than mixture of classical C i E j and complexing agent solubilized in the micelles. This reveals a synergistic effect of the covalent bond between the chelating group and the nonionic surfactant C i E j . This paper presents a systematic study of the extraction and aggregation properties and the influence of the nature of the ions. (authors)

  3. Impact of cationic surfactant on the self-assembly of sodium caseinate.

    Science.gov (United States)

    Vinceković, Marko; Curlin, Marija; Jurašin, Darija

    2014-08-27

    The impact of a cationic surfactant, dodecylammonium chloride (DDACl), on the self-assembly of sodium caseinate (SC) has been investigated by light scattering, zeta potential, and rheological measurements as well as by microscopy (transmission electron and confocal laser scanning microscopy). In SC dilute solutions concentration-dependent self-assembly proceeds through the formation of spherical associates and their aggregation into elongated structures composed of connected spheres. DDACl interacts with SC via its hydrophilic and hydrophobic groups, inducing changes in SC self-assembled structures. These changes strongly depend on the surfactant aggregation states (monomeric or micellar) as well as concentration ratio of both components, leading to the formation of soluble and insoluble complexes of nano- to microdimensions. DDACl monomers interact with SC self-assembled entities in a different way compared to their micelles. Surfactant monomers form soluble complexes (similar to surfactant mixed micelles) at lower SC concentration but insoluble gelatinous complexes at higher SC concentration. At surfactant micellar concentration soluble complexes with casein chains wrapped around surfactant micelles are formed. This study suggests that the use of proper cationic surfactant concentration will allow modification and control of structural changes of SC self-assembled entities.

  4. The Molecular Era of Surfactant Biology

    OpenAIRE

    Whitsett, Jeffrey A.

    2014-01-01

    Advances in the physiology, biochemistry, molecular and cell biology of the pulmonary surfactant system transformed the clinical care and outcome of preterm infants with respiratory distress syndrome. The molecular era of surfactant biology provided genetic insights into the pathogenesis of pulmonary disorders, previously termed “idiopathic” that affect newborn infants, children and adults. Knowledge related to the structure and function of the surfactant proteins and their roles in alveolar ...

  5. Effect of Micellization on the Adsorption Kinetics of Polymeric Surfactants to the Solid/Water Interface

    Science.gov (United States)

    Toomey, Ryan; Tirrell, Matthew

    2002-03-01

    We have studied the adsorption kinetics of two classes of hydrophobic/ionic diblock copolymer surfactants in aqueous environments to understand the role that micellization plays in the adsorption process. The two systems studied were poly(t-butyl styrene)-block-poly(styrene sulfonate) (PtBS-b-PSS) and polystyrene-block-poly(acrylic acid) (PS-b-PAA). It is found that by changing the hydrophobicity of the adsorbing surface, micelle adsorption can be turned on or off. When micelle adsorption occurs, the initial adsorption rate is always slower than the supply rate of micelles to the surface, indicating “reaction-limited” adsorption. Since these micelles have essentially frozen cores, the adsorption cannot be explained by the release of unimers from the micelles. Rather, micelles directly adsorb, and they have to overcome the potential barrier imposed by their corona. Due to micellization, the adsorption rate can also be a complex function of ionic strength. A regime was found where the initial adsorption rate decreased with increasing ionic strength. This anomaly can be explained by the onset of micellization. As the salt concentration is increased, more micelles are formed. However micelles adsorb roughly an order of magnitude slower than free chains. Therefore, if increasing the ionic strength produces more micelles, the adsorption rate will simultaneously decrease.

  6. Use of surfactants for the remediation of contaminated soils: A review

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Xuhui, E-mail: clab@whu.edu.cn [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Jiang, Rui; Xiao, Wei [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

    2015-03-21

    Highlights: • The recent advances in use of surfactant for soil remediation are reviewed. • The mechanisms of surfactant-based soil remediation are discussed. • A review on the application of different types of surfactants is made. • The future research direction of surfactant-based technologies is suggested. - Abstract: Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation.

  7. Use of surfactants for the remediation of contaminated soils: A review

    International Nuclear Information System (INIS)

    Mao, Xuhui; Jiang, Rui; Xiao, Wei; Yu, Jiaguo

    2015-01-01

    Highlights: • The recent advances in use of surfactant for soil remediation are reviewed. • The mechanisms of surfactant-based soil remediation are discussed. • A review on the application of different types of surfactants is made. • The future research direction of surfactant-based technologies is suggested. - Abstract: Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation

  8. The use of isothermal titration calorimetry to assess the solubility enhancement of simvastatin by a range of surfactants

    International Nuclear Information System (INIS)

    Patel, Rajesh; Buckton, Graham; Gaisford, Simon

    2007-01-01

    Surfactants are commonly used to increase the solubility of poorly water soluble drugs but the interactions between drug and surfactant can be complex and quantitative relationships can be hard to derive. One approach is to quantify the thermodynamics of interaction and relate these parameters to known solubility or dissolution rate enhancement data. Isothermal titration calorimetry (ITC) was used to measure the enthalpy and free energy of transfer of a model drug (simvastatin) to a number of surfactant (SDS, HTAB, SDCH and Brij 35) micelles. These data were then compared with the solubility enhancements determined for each surfactant using HPLC assays. As expected, there was correlation between the free energy of transfer for the drug to each surfactant and the solubility enhancement of that surfactant. Although the data set is limited, the results suggest that ITC screening of a range of surfactants against a poorly water soluble drug may allow the selection of the best potential solubilising surfactants

  9. Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

    International Nuclear Information System (INIS)

    Voisin, David

    2002-01-01

    Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each polyelectrolyte-surfactant particle in the region of the CAC, and just beyond, contains many polyelectrolyte chains, held together essentially by micelle bridges. These particles, however, remain net positively charged, and therefore stable. At the other end of the binding range of the surfactant, so many internal micelles are present that the polymer-surfactant particles are now net negatively charged. Indeed binding stops since no further micelles can be accommodated. Again, the particles are stable. However, there exists a range of surfactant concentrations, lying within the range referred to above, where the net charge is reduced sufficiently that the polymer-surfactant particles will flocculate to form much larger structures. The onset of this second range might be termed the 'critical flocculation concentration' (CFC), and the end, the 'critical stabilisation concentration' (CSC). In this work, the CFC and the CSC have been determined for mixtures of

  10. Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Voisin, David

    2002-07-01

    Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each polyelectrolyte-surfactant particle in the region of the CAC, and just beyond, contains many polyelectrolyte chains, held together essentially by micelle bridges. These particles, however, remain net positively charged, and therefore stable. At the other end of the binding range of the surfactant, so many internal micelles are present that the polymer-surfactant particles are now net negatively charged. Indeed binding stops since no further micelles can be accommodated. Again, the particles are stable. However, there exists a range of surfactant concentrations, lying within the range referred to above, where the net charge is reduced sufficiently that the polymer-surfactant particles will flocculate to form much larger structures. The onset of this second range might be termed the 'critical flocculation concentration' (CFC), and the end, the 'critical stabilisation concentration' (CSC). In this work, the CFC and

  11. Micelle-induced depletion interaction and resultant structure in charged colloidal nanoparticle system

    Energy Technology Data Exchange (ETDEWEB)

    Ray, D.; Aswal, V. K., E-mail: vkaswal@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kohlbrecher, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 PSI Villigen (Switzerland)

    2015-04-28

    The evolution of the interaction and the resultant structure in the mixed system of anionic silica nanoparticles (Ludox LS30) and non-ionic surfactant decaethylene glycol monododecylether (C12E10), undergoing phase separation, have been studied using small-angle neutron scattering and dynamic light scattering. The measurements have been carried out for a fixed concentration of nanoparticle (1 wt. %) with varying concentration of surfactant (0 to 1 wt. %), in the absence and presence of an electrolyte. It is found that the micelles of non-ionic surfactant adsorb on the nanoparticle in the absence of electrolyte (form stable system), whereas these micelles become non-adsorbing in the presence of electrolyte (show phase separation). The phase separation arises because of C12E10 micelles, causing depletion interaction between nanoparticles and leading to their aggregation. The interaction is modeled by double Yukawa potential accounting for attractive depletion as well as repulsive electrostatic forces. Both the interactions (attraction and repulsion) are found to be of long-range. The nanoparticle aggregation (phase separation) is governed by the increase in the magnitude and the range of the depletion attraction with the increase in the surfactant concentration. The nanoparticle aggregates formed are quite large in size (order of micron) and are characterized by the surface fractal having simple cubic packing of nanoparticles within the aggregates.

  12. Effect of a Long Chain Carboxylate Acid on Sodium Dodecyl Sulfate Micelle Structure: A Small-angle Neutron Scattering Study

    International Nuclear Information System (INIS)

    Arum Patriati; Edy Giri Rachman Putra

    2009-01-01

    The effect of different hydrocarbon chain length of carboxylate acid, i.e. dodecanoic acid, CH 3 (CH 2 ) 10 COOH and hexadecanoic acid, CH 3 (CH 2 ) 14 COOH as a co-surfactant in the 0.3M SDS micellar solution has been studied using small angle neutron scattering (SANS). Here, the present of dodecanoic acid has induced the SDS structural micelles. The ellipsoid micelles structures changed significantly in length (major axis) from 21.7 Armstrong to 35.5 Armstrong at a fixed minor axis of 16.7 Armstrong in the present of 0.005M to 0.1M dodecanoic acid. Nevertheless, this effect was not shown in the present of hexadecanoic acid with the same concentration range. The present of hexadecanoic acid molecules gave a small effect on growth of SDS micelles where the major axis of the micelle was simply elongated from 21.5 Armstrong to 23.5 Armstrong. It showed that the appropriate hydrocarbon chain length between surfactant and co-surfactant molecules is one of the determining factors in forming a mixed micelles structure. (author)

  13. Influence of system size and solvent flow on the distribution of wormlike micelles in a contraction-expansion geometry

    NARCIS (Netherlands)

    Stukan, M.R.; Boek, E.S.; Padding, J.T.; Crawshaw, J.P.

    2008-01-01

    Viscoelastic wormlike micelles are formed by surfactants assembling into elongated cylindrical structures. These structures respond to flow by aligning, breaking and reforming. Their response to the complex flow fields encountered in porous media is particularly rich. Here we use a realistic

  14. Degradation of surfactants by sono-irradiation

    International Nuclear Information System (INIS)

    Ashokkumar, M.; Grieser, F.; Vinodgopal, K.

    2000-01-01

    Full text: The ultrasound induced decomposition of a commercially available polydisperse nonylphenol ethoxylate surfactant (Teric GN9) has been investigated. Nearly 90% mineralization and/or degradation into volatile products of the surfactant is achieved after sonication for 24 hours. Ultrasound has been found to be a useful tool to achieve a number of chemical processes. Linear and branched alkyl benzene sulfonates and alkyl nonylphenol ethoxylates are widely used surfactants which accumulated in the environment and contribute to a well-recognised pollution problem. We have investigated the use of ultrasound in the degradation of both types of surfactants with the aim of understanding the mechanism of degradation in order to optimise the decomposition process. In this presentation, we report on the sonochemical degradation of Teric GN9- polydisperse, a nonylphenol ethoxylate with an average of 9 ethylene oxide units. The ultrasound unit used for the degradation studies of the surfactant solutions was an Allied Signal (ELAC Nautik) RF generator and transducer with a plate diameter of 54.5 mm operated at 363 kHz in continuous wave mode at an intensity of 2 W/cm 2 . Ultrasound induced cavitation events generate primary radicals inside gas/vapour filled bubbles. Due to the extreme conditions (T ∼ 5000 K; P ∼ 100 atm) generated within the collapsing bubble, H and OH radicals are produced by the homolysis of water molecules, if water is the medium of sonication. These primary radicals attack the surfactant molecules adsorbed at the bubble/water interface. The initial rate of reaction of the surfactant was found to be dependent on the monomer concentration in solution below and above the critical micelle concentration of the surfactants. This result strongly suggests that the initial radical attack on the surfactants occurs at the cavitation bubble/solution interface, followed by oxidative decomposition and pyrolysis of volatile fragments of the surfactant within

  15. Development of lycopene micelle and lycopene chylomicron and a comparison of bioavailability

    International Nuclear Information System (INIS)

    Chen, Yi Jyun; Inbaraj, Baskaran Stephen; Chen, Bing Huei; Pu, Yeong Shiau

    2014-01-01

    The objectives of this study were to develop lycopene micelles and lycopene chylomicrons from tomato extracts for the enhancement and comparison of bioavailability. Lycopene micelles and chylomicrons were prepared by a microemulsion technique involving tomato extract, soybean oil, water, vitamin E and surfactant Tween 80 or lecithin in different proportions. The encapsulation efficiency of lycopene was 78% in micelles and 80% in chylomicrons, with shape being roughly spherical and mean particle size being 7.5 and 131.5 nm. A bioavailability study was conducted in rats by both gavage and i.v. administration, with oral bioavailability of lycopene, phytoene and phytofluene being 6.8, 4.3 and 3.1% in micelles and 9.5, 9.4 and 7.1% in chylomicrons, respectively. This outcome reveals higher lycopene bioavailability through incorporation into micelle or chylomicron systems. Both size and shape should be considered for oral bioavailability determination. For i.v. injection, lycopene micelles should be more important than lycopene chylomicrons for future clinical applications. (paper)

  16. Development of lycopene micelle and lycopene chylomicron and a comparison of bioavailability

    Science.gov (United States)

    Jyun Chen, Yi; Inbaraj, Baskaran Stephen; Shiau Pu, Yeong; Chen, Bing Huei

    2014-04-01

    The objectives of this study were to develop lycopene micelles and lycopene chylomicrons from tomato extracts for the enhancement and comparison of bioavailability. Lycopene micelles and chylomicrons were prepared by a microemulsion technique involving tomato extract, soybean oil, water, vitamin E and surfactant Tween 80 or lecithin in different proportions. The encapsulation efficiency of lycopene was 78% in micelles and 80% in chylomicrons, with shape being roughly spherical and mean particle size being 7.5 and 131.5 nm. A bioavailability study was conducted in rats by both gavage and i.v. administration, with oral bioavailability of lycopene, phytoene and phytofluene being 6.8, 4.3 and 3.1% in micelles and 9.5, 9.4 and 7.1% in chylomicrons, respectively. This outcome reveals higher lycopene bioavailability through incorporation into micelle or chylomicron systems. Both size and shape should be considered for oral bioavailability determination. For i.v. injection, lycopene micelles should be more important than lycopene chylomicrons for future clinical applications.

  17. Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

    Science.gov (United States)

    Smith, Douglas D.; Hiller, John M.

    1998-01-01

    The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration.

  18. Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

    Science.gov (United States)

    Smith, D.D.; Hiller, J.M.

    1998-02-24

    The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration. 1 fig.

  19. Extraction of cobalt ion using reverse-micelle of F-AOT in liquid/supercritical CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ko, M. S.; Jin, Y. W.; Kim, J. R.; Park, K. H.; Kim, H. D.; Kim, H. W. [Kyunghee Univ., Youngin (Korea, Republic of)

    2002-05-01

    A green decontamination method using CO{sub 2} as an environmentally benign solvent has been studied for removal of contaminant in the nuclear power plant. We developed a decontamination technique using CO{sub 2} for removal of contamination in working dresses. Owing to the low solubilizing, A reverse micelle system was developed. Fluorinated AOT was synthesized and used as surfactants forming reverse-micelle with water. Cobalt was extracted by dissolution into reverse-micelle in liquid CO{sub 2}. If this decontamination technique is applied to nuclear industry, the secondary waste during decontamination will be reverentially reduced. Negligibly small amount of water is a net waste, while the surfactants and solvent CO{sub 2} are recovered and reused in the system.

  20. Structure formation of lipid membranes: Membrane self-assembly and vesicle opening-up to octopus-like micelles

    Science.gov (United States)

    Noguchi, Hiroshi

    2013-02-01

    We briefly review our recent studies on self-assembly and vesicle rupture of lipid membranes using coarse-grained molecular simulations. For single component membranes, lipid molecules self-assemble from random gas states to vesicles via disk-shaped clusters. Clusters aggregate into larger clusters, and subsequently the large disks close into vesicles. The size of vesicles are determined by kinetics than by thermodynamics. When a vesicle composed of lipid and detergent types of molecules is ruptured, a disk-shaped micelle called bicelle can be formed. When both surfactants have negligibly low critical micelle concentration, it is found that bicelles connected with worm-like micelles are also formed depending on the surfactant ratio and spontaneous curvature of the membrane monolayer.

  1. Reverse micelles as suitable microreactor for increased biohydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Anjana [Nanotechnology and Molecular Biology Laboratory, Centre of Biotechnology, University of Allahabad, Allahabad 211002 (India); Pandey, Ashutosh [Centre of Energy Studies, MNNIT, Allahabad 211004 (India)

    2008-01-15

    Reverse micelles have been shown to act as efficient microreactors for enzymic reactions and whole cell entrapment in organic (non-aqueous) media wherein the reactants are protected from denaturation by the surrounding organic solvent. These micelles are thermodynamically stable, micrometer sized water droplets dispersed in an organic phase by a surfactant. It has been observed that when whole cells of photosynthetic bacteria (Rhodopseudomonas sphaeroides or Rhodobacter sphaeroides 2.4.1) are entrapped inside these reverse micelles, the H{sub 2} production enhanced from 25 to 35 folds. That is, 1.71mmol(mgprotein){sup -1}h{sup -1} in case of R. sphaeroides which is 25 fold higher in benzene-sodium lauryl sulfate reverse micelles. Whereas, in case of R. sphaeroides 2.4.1 the H{sub 2} production was increased by 35 fold within AOT-isooctane reverse micelles i.e. 11.5mmol(mgprotein){sup -1}h{sup -1}. The observations indicate that the entrapment of whole cells of microbes within reverse micelles provides a novel and efficient technique to produce hydrogen by the inexhaustible biological route. The two microorganisms R. sphaeroides 2.4.1 (a photosynthetic bacteria) and Citrobacter Y19 (a facultative anaerobic bacteria) together are also entrapped within AOT-isooctane and H{sub 2} production was measured i.e. 69mmol(mgprotein){sup -1}h{sup -1}. The nitrogenase enzyme responsible for hydrogen production by R. sphaeroides/R. sphaeroides 2.4.1 cells is oxygen sensitive, and very well protected within reverse micelles by the use of combined approach of two cells (R. sphaeroides 2.4.1 and Citrobacter Y19). In this case glucose present in the medium of Citrobacter Y19 serves double roles in enhancing the sustained production rate of hydrogen. Firstly, it quenches the free O{sub 2}liberated as a side product of reaction catalyzed by nitrogenase, which is O{sub 2} labile. Secondly, organic acid produced by this reaction is utilized by the Citrobacter Y19 as organic substrate in

  2. NMR studies of electrophoretic mobility in surfactant systems

    International Nuclear Information System (INIS)

    Conveney, F.M.; Strange, J.H.; Smith, A.L.; Smith, E.G.

    1989-01-01

    An experimental technique is described in which the flow of electrically charged micelles is measured in the presence of an applied electric field using an NMR technique. The method is used to determine the electrophoretic mobility at ambient temperature of a 5% aqueous solution of sodium dodecyl sulphate and is shown to provide a new technique for the study of electrophoresis in surfactant solutions. (author). 8 refs.; 4 figs

  3. The study of the influence of surfactant charge on alkaline hydrolysis reactions of acetylsalicylic acid (ASA) and triflusal (TFL) using spectrophotometric methods.

    Science.gov (United States)

    Ferrit, Mónica; del Valle, Carmen; Martínez, Fernando

    2007-07-01

    In this research, the effects of micellar systems on alkaline hydrolysis reactions of acetylsalicylic acid (ASA) and triflusal (TFL) were found to be dependant upon the surfactant charge within the micelle. In cationic micelles, there is a catalytic effect at low concentrations of surfactant. However, this reaction is inhibited at higher surfactant concentrations. In anionic micelles, a catalytic effect occurs, while in zwitterionic and non-ionic micelles there is an inhibitory effect. Such reactions are attributable to changes in reactants on the micellar surface, or to the fact that both reactants are found in different microenvironments. The pseudophase (PS) and ion-exchange (PPIE) models were found to be consistent with the experimental result. Furthermore, the association constants for both drugs could be determined together with micellar rate constants in heterogeneous media.

  4. pKa values of hyodeoxycholic and cholic acids in the binary mixed micelles sodium-hyodeoxycholate-Tween 40 and sodium-cholate-Tween 40: Thermodynamic stability of the micelle and the cooperative hydrogen bond formation with the steroid skeleton.

    Science.gov (United States)

    Poša, Mihalj; Pilipović, Ana; Bećarević, Mirjana; Farkaš, Zita

    2017-01-01

    Due to a relatively small size of bile acid salts, their mixed micelles with nonionic surfactants are analysed. Of the special interests are real binary mixed micelles that are thermodynamically more stable than ideal mixed micelles. Thermodynamic stability is expressed with an excess Gibbs energy (G E ) or over an interaction parameter (β ij ). In this paper sodium salts of cholic (C) and hyodeoxycholic acid (HD) in their mixed micelles with Tween 40 (T40) are analysed by potentiometric titration and their pKa values are determined. Examined bile acids in mixed micelles with T40 have higher pKa values than free bile acids. The increase of ΔpKa acid constant of micellary bound C and HD is in a correlation with absolute values of an interaction parameter. According to an interaction parameter and an excess Gibbs energy, mixed micelle HD-T40 are thermodynamically more stable than mixed micelles C-T40. ΔpKa values are higher for mixed micelles with Tween 40 whose second building unit is HD, related to the building unit C. In both micellar systems, ΔpKa increases with the rise of a molar fraction of Tween 40 in binary mixtures of surfactants with sodium salts of bile acids. This suggests that, ΔpKa can be a measure of a thermodynamic stabilization of analysed binary mixed micelles as well as an interaction parameter. ΔpKa values are confirmed by determination of a distribution coefficient of HD and C in systems: water phase with Tween 40 in a micellar concentration and 1-octanol, with a change of a pH value of a water phase. Conformational analyses suggests that synergistic interactions between building units of analysed binary micelles originates from formation of hydrogen bonds between steroid OH groups and polyoxyethylene groups of the T40. Relative similarity and spatial orientation of C 3 and C 6 OH group allows cooperative formation of hydrogen bonds between T40 and HD - excess entropy in formation of mixed micelle. If a water solution of analysed binary

  5. Glycation Reactions of Casein Micelles.

    Science.gov (United States)

    Moeckel, Ulrike; Duerasch, Anja; Weiz, Alexander; Ruck, Michael; Henle, Thomas

    2016-04-13

    After suspensions of micellar casein or nonmicellar sodium caseinate had been heated, respectively, in the presence and absence of glucose for 0-4 h at 100 °C, glycation compounds were quantitated. The formation of Amadori products as indicators for the "early" Maillard reaction were in the same range for both micellar and nonmicellar caseins, indicating that reactive amino acid side chains within the micelles are accessible for glucose in a comparable way as in nonmicellar casein. Significant differences, however, were observed concerning the formation of the advanced glycation end products (AGEs), namely, N(ε)-carboxymethyllysine (CML), pyrraline, pentosidine, and glyoxal-lysine dimer (GOLD). CML could be observerd in higher amounts in nonmicellar casein, whereas in the micelles the pyrraline formation was increased. Pentosidine and GOLD were formed in comparable amounts. Furthermore, the extent of protein cross-linking was significantly higher in the glycated casein micelles than in the nonmicellar casein samples. Dynamic light scattering and scanning electron microscopy showed that glycation has no influence on the size of the casein micelles, indicating that cross-linking occurs only in the interior of the micelles, but altered the surface morphology. Studies on glycation and nonenzymatic cross-linking can contribute to the understanding of the structure of casein micelles.

  6. Effect of chemical structure on the cloud point of some new non-ionic surfactants based on bisphenol in relation to their surface active properties

    Directory of Open Access Journals (Sweden)

    A.M. Al-Sabagh

    2011-06-01

    Full Text Available A series of non-ionic surfactants were prepared from bisphenol derived from acetone (A, acetophenone (AC and cyclohexanone (CH. The prepared bisphenols were ethoxylated at different degrees of ethylene oxide (27, 35, 43. The ethoxylated bisphenols were non-esterified by fatty acids; decanoic, lauric, myristic, palmitic, stearic, oleic, linoloic and linolinic. Some surface active properties for these surfactants were measured and calculated such as, surface tension [γ], critical micelle concentration [CMC], minimum area per molecule [Amin], surface excess [Cmax], free energy of micellization and adsorption [ΔGmic] and [ΔGads]. At a certain temperature, the cloud point was measured for these surfactants. From the obtained data it was found that; the cloud point is very sensitive to the increase of the alkyl chain length, content of ethylene oxide and degree of unsaturation. The core of bisphenol affected the cloud point sharply and they are ranked regarding bisphenol structure as BA > BCH > BAC. By inspection of the surface active properties of these surfactants, a good relation was obtained with their cloud points. The data were discussed on the light of their chemical structures.

  7. Radiochromic leuco dye micelle hydrogels: I. Initial investigation

    International Nuclear Information System (INIS)

    Jordan, Kevin; Avvakumov, Nikita

    2009-01-01

    This investigation reports the use of surfactants and colorless leuco triarylmethane dyes to form a new class of radiochromic micelle hydrogels for three-dimensional (3D) water-equivalent dosimetry. Gelatin gel samples with several surfactants and leuco dyes were prepared and evaluated for optical transparency, dose sensitivity and diffusion rates. The addition of Triton X-100, a non-ionic surfactant, at levels exceeding the critical micelle concentration provides a transparent hydrogel in which the water insoluble leuco Malachite Green (LMG) can dissolve. During irradiation, the LMG dye precursor converts to Malachite Green (MG + ). The most sensitive reported LMG gel formulation contains 0.3 mM LMG leuco dye, 16 mM trichloroacetic acid, 7 mM Triton X-100 and 4% w/w gelatin. A diffusion coefficient of 0.14 mm 2 h -1 was determined for MG + in this gel by fitting the time-dependent degradation of the transmission profile after irradiating half of the sample. The diffusion rate was three times lower than the standard radiochromic ferrous xylenol-orange (FX) gel. The primary feature of this 3D hydrogel is that it introduces transparent, radiochromic, micelle hydrogels. The radiochromic response to dose is instantaneous and images are stable for several hours. A dosimetric characterization revealed that the dose response is reproducible to within 10% over five separate batches and independent of both energy and dose rate. Uniform pre-irradiation of samples to 5 Gy provided a subsequent near linear response to greater than 110 Gy. LMG gels when read with a fast optical CT scanner can provide full 3D dose distributions in less than 30 min post-irradiation. LMG micelle gels scanned with a 633 nm light source are a promising system for quantitative water- or tissue-equivalent 3D dose verification in the 5-100 Gy dose range. These gels are useful for the scanning of larger volume dosimeters (i.e. >15 cm diameter) since they are easily prepared with inexpensive ingredients

  8. Contribution of Seawater Surfactants to Generated Primary Marine Aerosol Particles

    Science.gov (United States)

    Frossard, A. A.; Gerard, V.; Duplessis, P.; Kinsey, J. D.; Lu, X.; Zhu, Y.; Bisgrove, J.; Maben, J. R.; Long, M. S.; Chang, R.; Beaupre, S. R.; Kieber, D. J.; Keene, W. C.; Noziere, B.; Cohen, R. C.

    2017-12-01

    Surfactants account for minor fractions of total organic carbon in the ocean but may have major impacts on the surface tension of bursting bubbles at the sea surface that drive the production of primary marine aerosol particles (PMA). Surfactants associated with marine aerosol may also significantly reduce the surface tension of water thereby increasing the potential for cloud droplet activation and growth. During September and October 2016, PMA were produced from bursting bubbles in seawater using a high capacity generator at two biologically productive and two oligotrophic stations in the western North Atlantic, as part of a cruise on the R/V Endeavor. Surfactants were extracted from paired PMA and seawater samples, and their ionic compositions, total concentrations, and critical micelle concentrations (CMC) were quantified and compared for the four hydrographic stations. Higher surfactant concentrations were determined in the aerosol produced from biologically productive seawater compared to oligotrophic seawater, and the surfactants extracted from productive seawater were stronger (had lower CMCs) than those in the oligotrophic seawater. Surfactants associated with PMA and seawater in productive regions also varied over diel cycles, whereas those in the oligotrophic regions did not. This work demonstrates a direct link between surfactants in seawater and those in PMA.

  9. Effect of Molecular Weight and Molar Ratio of Dextran on Self-Assembly of Dextran Stearate Polymeric Micelles as Nanocarriers for Etoposide

    Directory of Open Access Journals (Sweden)

    Jaleh Varshosaz

    2012-01-01

    Full Text Available Amphiphilic polymer surfactants are composed of hydrophilic and hydrophobic polymers and are widely used in targeted drug delivery. The purpose of this study was the evaluation of the effect of molecular weight and molar ratio of dextran on physicochemical properties of dextran stearate polymeric micelles. Dextran stearate was synthesized by acylation of dextran with stearoyl chloride. Etoposide loaded polymeric micelles were prepared by dialysis method. The resulting micelles were evaluated for particle size, zeta potential, critical micelle concentration (CMC, drug loading capacity, and release efficiency. Cytotoxicity and cellular uptake of micelles were studied in CT-26 colorectal carcinoma cell line. Molecular weight and molar ratio of dextran-stearate were impressive on zeta potential, CMC, drug loading capacity, and release efficiency. Unlike polymer molecular weight, molar ratio of stearate had a significant effect on cytotoxicity and particle size of etoposide loaded micelles. Although molecular weight of dextran had no significant effect on cytotoxicity of micelles on CT-26 cells, it had drastic attributes for stability of polymeric micelles. Consequently, both variables of molecular weight of dextran and molar ratio of stearate should be taken into account to have a stable and effective micelle of dextran-stearate.

  10. Combined ultrasound/ozone degradation of carbazole in APG{sub 1214} surfactant solution

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Guodong, E-mail: jiguodong@iee.pku.edu.cn [Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871 (China); Zhang, Baolong; Wu, Yingchao [Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871 (China)

    2012-07-30

    Highlights: Black-Right-Pointing-Pointer We first describe the role of US/O{sub 3} in promoting carbazole degradation in APG{sub 1214} solution. Black-Right-Pointing-Pointer 20 W ultrasound for 30 min improves the effectiveness of carbazole ozonolysis by 5-10%. Black-Right-Pointing-Pointer 40 W or 80 W only plays a role in promoting degradation of carbazole in the first 5 min. Black-Right-Pointing-Pointer The content of {center_dot}OH radical is inversely proportional to the ultrasound power. Black-Right-Pointing-Pointer Absolute value of zeta potential of APG{sub 1214} micelles is inversely proportional to US power. - Abstract: We examined the effects of power and treatment time on the ultrasonically enhanced ozonation of carbazole dissolved in APG{sub 1214} surfactant solutions, including an analysis of the mechanism of {center_dot}OH radical formation, the zeta potential of the colloidal suspension, the influence of ultrasound on micellar morphology, and the degradation kinetics for carbazole and APG{sub 1214}. A 30 min ultrasound treatment at 28 kHz and 20 W improved the degradation of carbazole by 5-10%, while power levels of 40 W and 80 W provided improvements only during the first 5 min and resulted in reduced degradation after 15 min. The {center_dot}OH concentration was inversely proportional to ultrasound power, and directly proportional to the irradiation time. The absolute value of the APG{sub 1214} micelle zeta potential was inversely proportional to power and decreased with increasing irradiation time. The relationships of {center_dot}OH radical concentration in APG{sub 1214} micelles, the zeta potential, and the micellar dynamic radius (R{sub h}) to ultrasonic power and time are the key factors affecting carbazole degradation in this system.

  11. Combined ultrasound/ozone degradation of carbazole in APG1214 surfactant solution

    International Nuclear Information System (INIS)

    Ji, Guodong; Zhang, Baolong; Wu, Yingchao

    2012-01-01

    Highlights: ► We first describe the role of US/O 3 in promoting carbazole degradation in APG 1214 solution. ► 20 W ultrasound for 30 min improves the effectiveness of carbazole ozonolysis by 5–10%. ► 40 W or 80 W only plays a role in promoting degradation of carbazole in the first 5 min. ► The content of ·OH radical is inversely proportional to the ultrasound power. ► Absolute value of zeta potential of APG 1214 micelles is inversely proportional to US power. - Abstract: We examined the effects of power and treatment time on the ultrasonically enhanced ozonation of carbazole dissolved in APG 1214 surfactant solutions, including an analysis of the mechanism of ·OH radical formation, the zeta potential of the colloidal suspension, the influence of ultrasound on micellar morphology, and the degradation kinetics for carbazole and APG 1214 . A 30 min ultrasound treatment at 28 kHz and 20 W improved the degradation of carbazole by 5–10%, while power levels of 40 W and 80 W provided improvements only during the first 5 min and resulted in reduced degradation after 15 min. The ·OH concentration was inversely proportional to ultrasound power, and directly proportional to the irradiation time. The absolute value of the APG 1214 micelle zeta potential was inversely proportional to power and decreased with increasing irradiation time. The relationships of ·OH radical concentration in APG 1214 micelles, the zeta potential, and the micellar dynamic radius (R h ) to ultrasonic power and time are the key factors affecting carbazole degradation in this system.

  12. Synthesis, surface properties and oil solubilisation capacity of cationic gemini surfactants

    NARCIS (Netherlands)

    Dam, Th.; Engberts, J.B.F.N.; Karthäuser, J.; Karaborni, S.; Os, N.M. van

    1996-01-01

    The critical micelle concentration (CMC) and the surface tension at the CMC have been determined for the gemini surfactants alkanediyl-u,w-bis(dimethyla1kylammoniubmr omide) by means of dynamic surface tension measurements. For the same number of carbon atoms in the hydrophobic chain per hydrophilic

  13. Optimized mixed oils remarkably reduce the amount of surfactants in microemulsions without affecting oral bioavailability of ibuprofen by simultaneously enlarging microemulsion areas and enhancing drug solubility.

    Science.gov (United States)

    Chen, Yizhen; Tuo, Jue; Huang, Huizhi; Liu, Dan; You, Xiuhua; Mai, Jialuo; Song, Jiaqi; Xie, Yanqi; Wu, Chuanbin; Hu, Haiyan

    2015-06-20

    The toxicity and irritation associated with high amounts of surfactants restrict the extensive utilization of microemulsions. To address these shortcomings, employing mixed oils to enlarge microemulsion areas therefore reducing surfactant contents is a promising strategy. However, what kinds of mixed oils are more efficient in enlarging microemulsion areas still remains unclear. In this research, we found that the chain length and degree of unsaturation of oils play a key role in enlarging microemulsion areas. The combination of moderate chain saturated oil caprylic/capric triglyceride (GTCC) with long chain unsaturated oil glycerol trioleate significantly increased the microemulsion areas. Solubility of ibuprofen in the mixed oils was unexpectedly and remarkably increased (almost 300mg/mL) compared with that (around 100mg/mL) of the single oil (GTCC), which also resulted in greatly increased solubility of ibuprofen in mixed oils-containing microemulsions. By optimizing the mixed oil formulation, the absolute amount of surfactant in drug-loaded microemulsions was reduced but increased drug oral bioavailability in rats was maintained. It could be concluded that the combined use of moderate chain oils and long chain unsaturated oils could not only acquire enlarged microemulsion areas but also enhanced drug solubility, therefore doubly reducing surfactant amount, which is extremely beneficial for developing safe microemulsions. Copyright © 2015. Published by Elsevier B.V.

  14. Smart worm-like micelles responsive to CO2/N2 and light dual stimuli.

    Science.gov (United States)

    Jiang, Jianzhong; Wang, Guozheng; Ma, Yuxuan; Cui, Zhenggang; Binks, Bernard P

    2017-04-12

    CO 2 /N 2 and light dual stimuli-responsive worm-like micelles (WLMs) were obtained by addition of a relatively small amount of a switchable surfactant, 4-butyl-4'-(4-N,N-dimethylhexyloxy-amine) azobenzene bicarbonate (AZO-B6-CO 2 ), sensitive to the same triggers to a binary aqueous solution of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal).

  15. Surfactant-enhanced spectrofluorimetric determination of total aflatoxins from wheat samples after magnetic solid-phase extraction using modified Fe3O4 nanoparticles

    Science.gov (United States)

    Manafi, Mohammad Hanif; Allahyari, Mehdi; Pourghazi, Kamyar; Amoli-Diva, Mitra; Taherimaslak, Zohreh

    2015-07-01

    The extraction and preconcentration of total aflatoxins (including aflatoxin B1, B2, G1, and G2) using magnetic nanoparticles based solid phase extraction (MSPE) followed by surfactant-enhanced spectrofluorimetric detection was proposed. Ethylene glycol bis-mercaptoacetate modified silica coated Fe3O4 nanoparticles as an efficient antibody-free adsorbent was successfully applied to extract aflatoxins from wheat samples. High surface area and strong magnetization properties of magnetic nanoparticles were utilized to achieve high enrichment factor (97), and satisfactory recoveries (92-105%) using only 100 mg of the adsorbent. Furthermore, the fast separation time (less than 10 min) avoids many time-consuming cartridge loading or column-passing procedures accompany with the conventional SPE. In determination step, signal enhancement was performed by formation of Triton X-100 micelles around the analytes in 15% (v/v) acetonitrile-water which dramatically increase the sensitivity of the method. Main factors affecting the extraction efficiency and signal enhancement of the analytes including pH of sample solution, desorption conditions, extraction time, sample volume, adsorbent amount, surfactant concentration and volume and time of micelle formation were evaluated and optimized. Under the optimum conditions, wide linear range of 0.1-50 ng mL-1 with low detection limit of 0.03 ng mL-1 were obtained. The developed method was successfully applied to the extraction and preconcentration of aflatoxins in three commercially available wheat samples and the results were compared with the official AOAC method.

  16. Preclinical safety evaluation of intravenously administered mixed micelles.

    Science.gov (United States)

    Teelmann, K; Schläppi, B; Schüpbach, M; Kistler, A

    1984-01-01

    Mixed micelles, with their main constituents lecithin and glycocholic acid, form a new principle for the parenteral administration of compounds which are poorly water-soluble. Their composition of mainly physiological substances as well as their comparatively good stability substantiate their attractivity in comparison to existing solvents. A decomposition due to physical influences such as heat or storage for several years will almost exclusively affect the lecithin component in the form of hydrolysis into free fatty acids and lysolecithin. Their toxicity was examined experimentally in various studies using both undecomposed and artificially decomposed mixed micelles. In these studies the mixed micelles were locally and systemically well tolerated and proved to be neither embryotoxic, teratogenic nor mutagenic. Only when comparatively high doses of the undecomposed mixed micelles were administered, corresponding to approximately 30 to 50 times the anticipated clinical injection volume (of e.g. diazepam mixed micelles), did some vomitus (dogs), slight liver enzyme elevation (rats and dogs), and slightly increased liver weights (dogs) occur. After repeated injections of the artificially decomposed formulation (approximately 25% of lecithin hydrolyzed to free fatty acids and lysolecithin) effects such as intravascular haemolysis, liver enzyme elevations and intrahepatic cholestasis (dogs only) were observed but only when doses exceeding a threshold of approximately 40 to 60 mg lysolecithin/kg body weight were administered. All alterations were reversible after cessation of treatment.

  17. Thermodynamic aspects of polymer–surfactant interactions: Gemini (16-5-16-PVP-water system

    Directory of Open Access Journals (Sweden)

    Naved Azum

    2016-11-01

    Full Text Available The interaction between polyvinylpyrrolidone (PVP and gemini surfactant (16-5-16 in aqueous solution has been analyzed using conductometry. From conductivity data the critical aggregation concentration (cac, critical micelle concentration (cmc, the effective degree of counter-ion binding (β at different temperatures were obtained. The thermodynamic parameters, i.e., Gibbs energy of aggregation and micellization, standard enthalpy of aggregation, and standard entropy of aggregation of surfactant/polymer system were estimated, employing pseudophase separation model. The negative values of Gibbs energy and standard enthalpy suggest that the surfactant/polymer aggregation process is spontaneous and exothermic respectively.

  18. Light and neutron scattering study of strongly interacting ionic micelles

    International Nuclear Information System (INIS)

    Degiorgio, V.; Corti, M.; Piazza, R.

    1989-01-01

    Dilute solutions of ionic micelles formed by biological glycolipids (gangliosides) have been investigated at various ionic strengths by static and dynamic light scaterring and by small-angle neutron scattering. The size and shape of the micelle is not appreciably affected by the added salt concentration in the range 0-100 mM NaCL. From the measured intensity of scattered light we derive the electric charge Z of the micelle by fitting the data to a theoretical calculation which uses a screened Coulomb potential for the intermicellar interaction, and the hypernetted chain approximation for the calculation of the radial distribution function. The correlation function derived from dynamic light scattering shows the long time contribution typical of concentrated polydisperse systems (author). 15 refs.; 6 figs

  19. Alteration in cell surface properties of Burkholderia spp. during surfactant-aided biodegradation of petroleum hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Sagarika; Mukherji, Suparna [Indian Institute of Technology Bombay, Mumbai (India). Centre for Environmental Science and Engineering (CESE)

    2012-04-15

    Chemical surfactants may impact microbial cell surface properties, i.e., cell surface hydrophobicity (CSH) and cell surface charge, and may thus affect the uptake of components from non-aqueous phase liquids (NAPLs). This work explored the impact of Triton X-100, Igepal CA 630, and Tween 80 (at twice the critical micelle concentration, CMC) on the cell surface characteristics of Burkholderia cultures, Burkholderia cepacia (ES1, aliphatic degrader) and Burkholderia multivorans (NG1, aromatic degrader), when grown on a six-component model NAPL. In the presence of Triton X-100, NAPL biodegradation was enhanced from 21% to 60% in B. cepacia and from 18% to 53% in B. multivorans. CSH based on water contact angle (50-52 ) was in the same range for both strains while zeta potential at neutral pH was -38 and -31 mV for B. cepacia and B. multivorans, respectively. In the presence of Triton X-100, their CSH increased to greater than 75 and the zeta potential decreased. This induced a change in the mode of uptake and initiated aliphatic hydrocarbon degradation by B. multivorans and increased the rate of aliphatic hydrocarbon degradation in B. cepacia. Igepal CA 630 and Tween 80 also altered the cell surface properties. For B. cepacia grown in the presence of Triton X-100 at two and five times its CMC, CSH increased significantly in the log growth phase. Growth in the presence of the chemical surfactants also affected the abundance of chemical functional groups on the cell surface. Cell surface changes had maximum impact on NAPL degradation in the presence of emulsifying surfactants, Triton X-100 and Igepal CA630.

  20. Solubilization of docetaxel in poly(ethylene oxide)-block-poly(butylene/styrene oxide) micelles.

    Science.gov (United States)

    Elsabahy, Mahmoud; Perron, Marie-Eve; Bertrand, Nicolas; Yu, Ga-Er; Leroux, Jean-Christophe

    2007-07-01

    Poly(ethylene oxide)-block-poly(styrene oxide) (PEO-b-PSO) and PEO-b-poly(butylene oxide) (PEO-b-PBO) of different chain lengths were synthesized and characterized for their self-assembling properties in water by dynamic/static light scattering, spectrofluorimetry, and transmission electron microscopy. The resulting polymeric micelles were evaluated for their ability to solubilize and protect the anticancer drug docetaxel (DCTX) from degradation. The drug release kinetics as well as the cytotoxicity of the loaded micelles were assessed in vitro. All polymers formed micelles with a highly viscous core at low critical association concentrations (hydrolysis under accelerated stability testing conditions. Only PEO-b-PBO bearing 24 BO units afforded significant protection against degradation. In vitro, DCTX was released slower from the latter micelles, but all formulations possessed a similar cytotoxic effect against PC-3 prostate cancer cells. These data suggest that PEO-b-P(SO/BO) micelles could be used as alternatives to conventional surfactants for the solubilization of taxanes.

  1. Adsorption of anionic surfactants in limestone medium during oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Canbolat, Serhat; Bagci, Suat [Middle East Technical Univ., Dept. of Petroleum and Natural Gas Engineering, Ankara (Turkey)

    2004-07-15

    Foam-forming surfactant performance was evaluated by several experimental methods (interfacial tension, foam stability, corefloods) using commercial surfactants. There is considerable interest in the use of foam-forming surfactants for mobility control in water flood. To provide effective mobility control, the injected surfactant must propagate from the injection well toward the production well. One of the important parameters affecting propagation of foam-forming surfactant through the reservoir is the retention of surfactant due to its adsorption on reservoir rock. The determination of the adsorption of foam-forming surfactants in limestone reservoirs is important for the residual oil recovery efficiency. Adsorption measurements, recovery efficiencies, and surfactant and alkaline flooding experiments carried out with the representative of the selected surfactants alkaline solutions, linear alkyl benzene sulphonic acid (LABSA), sodium lauryl ether sulfate (SLES), and NaOH in a limestone medium. These surfactants were selected with respect to their foaming ability. Calibration curves formed by pH measurements were used to determine the correct adsorption amount of the used surfactants and recovery efficiency of these surfactants compared with base waterflooding. The results showed that LABSA adsorbed more than SLES in limestone reservoirs. The recovery efficiency of SLES was higher than the recovery efficiency of LABSA, and they decreased the recovery efficiency with respect to only the water injection case. (Author)

  2. Alkali/Surfactant/Polymer Flooding in the Daqing Oilfield Class II Reservoirs Using Associating Polymer

    Directory of Open Access Journals (Sweden)

    Ru-Sen Feng

    2013-01-01

    Full Text Available Hydrophobically modified associating polyacrylamide (HAPAM has good compatibility with the Daqing heavy alkylbenzene sulfonate surfactant. The HAPAM alkali/surfactant/polymer (ASP system can generate ultralow interfacial tension in a wide range of alkali/surfactant concentrations and maintain stable viscosity and interfacial tension for 120 days. The HAPAM ASP system has good injectivity for the Daqing class II reservoirs (100–300 × 10−3 μm2 and can improve oil recovery by more than 25% on top of water flooding. In the presence of both the alkali and the surfactant, the surfactant interacts with the associating groups of the polymer to form more micelles, which can significantly enhance the viscosity of the ASP system. Compared with using HPAM (Mw = 2.5 MDa, using HAPAM can reduce the polymer use by more than 40%.

  3. Effect of different reversed micelles on autooxidation and photooxidation of stripped corn oil

    Directory of Open Access Journals (Sweden)

    Schwarz, K.

    2003-03-01

    Full Text Available The effect of reversed micelles (RMs in combination with α -tocopherol and Trolox was evaluated on the autooxidation and photooxidation of stripped corn oil. Oxidation was followed by measuring hydroperoxide and hexanal formation. RMs affected the oil oxidation stability to a degree depending on the surfactant used. Lecithin RMs caused a stronger decrease in oxidation than polyglyceryl-3-oleate RMs and methylglucose dioleate RMs. All RMs reduced the inhibition of oxidation when added in combination with external antioxidant.El efecto de miscelas inversas (RMs en combinación con α-tocoferol y Trolox fue evaluado en la autooxidación y fotooxidación de aceite de maíz libre de antioxidantes. La oxidación fue seguida por la medida de la formación de hexanal e hidroperóxido. Las RMs influyeron en la estabilidad de la oxidación del aceite dependiendo del tensioactivo usado. Las RMs de lecitina causaron una mayor disminución en la oxidación que las RMs de poligliceril-3-oleato y las RMs de metilglucosa dioleato. Todas las RMs redujeron la inhibición de la oxidación cuando se añadieron en combinación con antioxidantes externos.

  4. A Study on Solubilization of Poorly Soluble Drugs by Cyclodextrins and Micelles: Complexation and Binding Characteristics of Sulfamethoxazole and Trimethoprim

    Directory of Open Access Journals (Sweden)

    Sinem Göktürk

    2012-01-01

    > α-CD. With taking into consideration of solubilization capacity of SDS micelles, it has been found that the solubility enhancement of TMP is much higher than that of SMX in the presence of SDS micelles. The binding constants of SMX and TMP obtained from the Benesi-Hildebrand equation are also confirmed by the estimated surface properties of SDS, employing the surface tension measurements. In order to elucidate the solubilization characteristics the surface tension measurements were also performed for nonionic surfactant Triton X-100. Polarity of the microenvironment and probable location of SMX and TMP were also discussed in the presence of various organic solvents.

  5. Atrazine and Diuron partitioning within a soil-water-surfactant system

    Science.gov (United States)

    Wang, P.; Keller, A.

    2006-12-01

    The interaction between pesticide and soil and water is even more complex in the presence of surfactants. In this study, batch equilibrium was employed to study the sorption of surfactants and the partitioning behaviors of Atrazine and Diuron within a soil-water-surfactant system. Five soils and four surfactants (nonionic Triton- 100, cationic Benzalkonium Chloride (BC), anionic Linear Alkylbenzenesulfonate (LAS), and anionic Sodium Dodecyl Sulfate (SDS)) were used. All surfactant sorption isotherms exhibited an initial linear increase at low surfactant concentrations but reached an asymptotic value as the surfactant concentrations increased. Among the surfactants, BC had the highest sorption onto all soils, followed by Triton-100 and then by LAS and SDS, implying that the nature of the charge significantly influences surfactant sorption. Sorption of either Triton-100 or BC was highly correlated with soil Cation Exchange Capacity (CEC) while that of LAS and SDS was complicated by the presence of Ca2+ and Mg2+ in the aqueous phase and the CEC sites. Both LAS and SDS formed complexes with Ca2+ and Mg2+, resulting in a significant decrease in the detergency of the surfactants. At high surfactant concentrations and with micelles present in the aqueous phase, the micelles formed a more competitive partitioning site for the pesticides, resulting in less pesticide sorbed to the soil. At low Triton-100 and BC concentration, the sorption of the surfactants first resulted in less Atrazine sorption but more Diuron sorption, implying competition between the surfactants and Atrazine, which serves as an indirect evidence that there is a different sorption mechanism for Atrazine. Atrazine is a weak base and it protonates and becomes positively charged near particle surfaces where the pH is much lower than in the bulk solution. The protonated Atrazine may then be held on the CEC sites via electrostatic attraction. Triton-100, LAS and SDS sorbed on the soil showed similar

  6. Polymeric micelles for drug targeting.

    Science.gov (United States)

    Mahmud, Abdullah; Xiong, Xiao-Bing; Aliabadi, Hamidreza Montazeri; Lavasanifar, Afsaneh

    2007-11-01

    Polymeric micelles are nano-delivery systems formed through self-assembly of amphiphilic block copolymers in an aqueous environment. The nanoscopic dimension, stealth properties induced by the hydrophilic polymeric brush on the micellar surface, capacity for stabilized encapsulation of hydrophobic drugs offered by the hydrophobic and rigid micellar core, and finally a possibility for the chemical manipulation of the core/shell structure have made polymeric micelles one of the most promising carriers for drug targeting. To date, three generations of polymeric micellar delivery systems, i.e. polymeric micelles for passive, active and multifunctional drug targeting, have arisen from research efforts, with each subsequent generation displaying greater specificity for the diseased tissue and/or targeting efficiency. The present manuscript aims to review the research efforts made for the development of each generation and provide an assessment on the overall success of polymeric micellar delivery system in drug targeting. The emphasis is placed on the design and development of ligand modified, stimuli responsive and multifunctional polymeric micelles for drug targeting.

  7. Molecular recognition of nucleotides in micelles and the development and expansion of a chemistry outreach program

    Science.gov (United States)

    Schechinger, Linda Sue

    I. To investigate the delivery of nucleotide-based drugs, we are studying molecular recognition of nucleotide derivatives in environments that are similar to cell membranes. The Nowick group previously discovered that membrane-like surfactant micelles tetradecyltrimethylammonium bromide (TTAB) micelle facilitate molecular of adenosine monophosphate (AMP) recognition. The micelles bind nucleotides by means of electrostatic interactions and hydrogen bonding. We observed binding by following 1H NMR chemical shift changes of unique hexylthymine protons upon addition of AMP. Cationic micelles are required for binding. In surfactant-free or sodium dodecylsulfate solutions, no hydrogen bonding is observed. These observations suggest that the cationic surfactant headgroups bind the nucleotide phosphate group, while the intramicellar base binds the nucleotide base. The micellar system was optimized to enhance binding and selectivity for adenosine nucleotides. The selectivity for adenosine and the number of phosphate groups attached to the adenosine were both investigated. Addition of cytidine, guanidine, or uridine monophosphates, results in no significant downfield shifting of the NH resonance. Selectivity for the phosphate is limited, since adenosine mono-, di-, and triphosphates all have similar binding constants. We successfully achieved molecular recognition of adenosine nucleotides in micellar environments. There is significant difference in the binding interactions between the adenosine nucleotides and three other natural nucleotides. II. The UCI Chemistry Outreach Program (UCICOP) addresses the declining interest of the nations youth for science. UCICOP brings fun and exciting chemistry experiments to local high schools, to remind students that science is fun and has many practical uses. Volunteer students and alumni of UCI perform the demonstrations using scripts and material provided by UCICOP. The preparation of scripts and materials is done by two coordinators

  8. Influence of stability of polymer surfactant on oil displacement mechanism

    Science.gov (United States)

    Liu, Li; Li, Chengliang; Pi, Yanming; Wu, Di; He, Ying; Geng, Liang

    2018-02-01

    At present, most of the oilfields of China have entered the late stage of high water-cut development, and three oil recovery technique has become the leading technology for improving oil recovery. With the improvement of three oil recovery techniques, the polymer surfactant flooding technology has been widely promoted in oil fields in recent years. But in the actual field experiment, it has been found that the polymer surfactant has chromatographic separation at the extraction end, which indicates that the property of the polymer surfactant has changed during the displacement process. At present, there was few literature about how the stability of polymer surfactant affects the oil displacement mechanism. This paper used HuaDing-I polymer surfactant to conduct a micro photolithography glass flooding experiment, and then compared the oil displacement law of polymer surfactant before and after static setting. Finally, the influence law of stability of polymer surfactant on the oil displacement mechanism is obtained by comprehensive analysis.

  9. Improved microbial growth inhibition activity of bio-surfactant induced Ag–TiO{sub 2} core shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nithyadevi, D. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046 (India); Kumar, P. Suresh [Thin Film and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Mangalaraj, D., E-mail: dmraj800@yahoo.com [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046 (India); Ponpandian, N.; Viswanathan, C. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046 (India); Meena, P. [Department of Physics, PSGR Krishnammal college for women, Coimbatore 641 004 (India)

    2015-02-01

    Graphical abstract: - Highlights: • TiO{sub 2} nanoparticles were synthesized by hydrolysis process and Ag nanoparticles were prepared by using hydrazine reduction method. • Ag–TiO{sub 2} core shell nanoparticles were synthesized by reverse micelle method. • Coatings of TiO{sub 2} shell leads to decrease the usage of silver particles and also it reduces the release of silver ions from the matrix. • Optimum ratio of TiO{sub 2} particles: Ag atoms are needed for better antibacterial activity. • Sodium alginate (Bio-copolymer) induced core shell nanoparticles results 100% cell growth inhibition toward Staphylococcus aureus. - Abstract: Surfactant induced silver–titanium dioxide core shell nanoparticles within the size range of 10–50 nm were applied in the antibacterial agent to inhibit the growth of bacterial cells. The single crystalline silver was located in the core part of the composite powder and the titanium dioxide components were uniformly distributed in the shell part. HRTEM and XRD results indicated that silver was completely covered by titanium dioxide and its crystal structure was not affected after being coated by titanium dioxide. The effect of silver–titanium dioxide nanoparticles in the inhibition of bacterial cell growth was studied by means of disk diffusion method. The inhibition zone results reveal that sodium alginate induced silver–titanium dioxide nanoparticles exhibit 100% more antibacterial activity than that with cetyltrimethylbromide or without surfactant. UV–vis spectroscopic analysis showed a large concentration of silver was rapidly released into phosphate buffer solution (PBS) within a period of 1 day, with a much smaller concentration being released after this 1-day period. It was concluded that sodium alginate induced silver–titanium dioxide core shell nanoparticles could enhance long term cell growth inhibition in comparison with cetyltrimethylbromide or without surfactant. The surfactant mediated core shell

  10. Spectrophotometric determination of molybdenum with non-ionic surfactant and thiocyanate

    International Nuclear Information System (INIS)

    Hayashi, Kenjiro; Yamamoto, Atsuo; Fujimura, Yasue; Ito, Saburo.

    1980-01-01

    Although the molybdenum (V)-thiocyanate complex is quite stable in non-aqueous solvent such as ether, the complex in dilute acidic solution is unstable. However, this unstable complex was stabilized remarkably by addition of some non-ionic surfactant such as Triton X-100 (alkylphenolpolyoxyethylene ether). The application of this stabilizing effect of the surfactant to the photometric determination of trace amounts of molybdenum with thiocyanate resulted in an increase in the sensitivity. The rate of formation of the Mo(V)-SCN complex was affected by the presence of ferrous ion and its rate constant was proportional to the concentration of Fe(II). The stabilizing effect of the surfactant on the yellowish orange coloration can be understood if we assume that the Mo(V)-SCN complex is incorporated into the micelles of Triton X-100 as [H 2 + , MoO(CNS) 5 2- ]. The optimum condition for the determination of molybdenum is as follows: concentration of sulfuric acid, 0.22 mol dm -3 ; Triton X-100, 0.8%; ascorbic acid, 0.32 mol dm -3 ; thiocyanate, 0.30 mol dm -3 ; iron, 40 mg dm -3 ; standing time for coloration, 10 min and more. Beer's law was obeyed over the range (1 -- 233) μg/50 cm 3 . The molar absorption coefficient at 468 nm was 1.7 2 x 10 4 cm -1 mol -1 dm 3 . The maximum permissible limits of foreign ions (mg/50 cm 3 ) were as follows: Ni(30); Co(12); W(VI) (2); Cu, Zn, V(V) (3); Cr(VI) (5). Large amounts of iron interfered, but this interference was removed by addition of the same amount of iron to the reagent blank. Trace amounts of molybdenum in steel was determined by this method with satisfactory results. (author)

  11. The Formation of pH-Sensitive Wormlike Micelles in Ionic Liquids Driven by the Binding Ability of Anthranilic Acid

    Directory of Open Access Journals (Sweden)

    Qing You

    2015-11-01

    Full Text Available Wormlike micelles are typically formed by mixing cationic and anionic surfactants because of attractive interactions in oppositely charged head-groups. The structural transitions of wormlike micelles triggered by pH in ionic liquids composed of N-alkyl-N-methylpyrrolidinium bromide-based ILs (ionic liquids and anthranilic acid were investigated. These structures were found responsible for the variations in flow properties identified by rheology and dynamic light scattering, and account for the structures observed with cryogenic transmission electron microscopy (Cryo-TEM. High-viscosity, shear-thinning behavior, and Maxwell-type dynamic rheology shown by the system at certain pH values suggested that spherical micelles grow into entangled wormlike micelles. Light scattering profiles also supported the notion of pH-sensitive microstructural transitions in the solution. Cryo-TEM images confirmed the presence of spherical micelles in the low-viscosity sample and entangled wormlike micelles in the peak viscosity sample. Nuclear magnetic resonance spectroscopy analysis revealed that the pH sensitivity of ionic liquid systems originated from the pH-dependent binding ability of anthranilic acid to the cationic headgroup of ionic liquids.

  12. Surfactants in tribology

    CERN Document Server

    Biresaw, Girma

    2014-01-01

    Surface science and tribology play very critical roles in many industries. Manufacture and use of almost all consumer and industrial products rely on the application of advanced surface and tribological knowledge. The fourth in a series, Surfactants in Tribology, Volume 4 provides an update on research and development activities connecting surfactants and tribological phenomena. Written by renowned subject matter experts, the book demonstrates how improved design of surfactants can be harnessed to control tribological phenomena. Profusely illustrated and copiously referenced, the chapters also

  13. Effects of Surfactant on Geotechnical Characteristics of Silty Soil

    International Nuclear Information System (INIS)

    Rahman, Z.A.; Sahibin, A.R.; Lihan, T.; Idris, W.M.R.; Sakina, M.

    2013-01-01

    Surfactants are often used as a cleaning agent for restoration of oil-contaminated soil. However the effect of surfactant on the geotechnical properties of soil is not clearly understood. In this study, the effects of surfactant on silty soil were investigated for consistency index, compaction, permeability and shear strength. Sodium dodecyl sulfate (SDS) was used in this study to prepare the surfactant-treated soil. Our results showed that the soil with added surfactant exhibited a decrease in liquid and plastic limit values. Maximum dry densities increased and optimum moisture contents decreased as contents of added surfactant were increased. The presence of surfactant assists the soil to achieve maximum density at lower water content. The addition of surfactant decreased the permeability of soil from 6.29 x 10 -4 to 1.15 x 10 -4 ms -1 . The shear strength of soil with added surfactant was examined using the undrained unconsolidated triaxial tests. The results showed that the undrained shear strength, Cu was significantly affected, decreased from 319 kPa to 50 kPa for soil with 20 % of added surfactant. The results of this study showed that the presence of surfactant in soil can modify the mechanical behaviour of the soil. (author)

  14. Manipulating interfacial polymer structures through mixed surfactant adsorption and complexation.

    Science.gov (United States)

    Cattoz, Beatrice; de Vos, Wiebe M; Cosgrove, Terence; Crossman, Martin; Prescott, Stuart W

    2012-04-17

    The effects of a nonionic alcohol ethoxylate surfactant, C(13)E(7), on the interactions between PVP and SDS both in the bulk and at the silica nanoparticle interface are studied by photon correlation spectroscopy, solvent relaxation NMR, SANS, and optical reflectometry. Our results confirmed that, in the absence of SDS, C(13)E(7) and PVP are noninteracting, while SDS interacts strongly both with PVP and C(13)E(7) . Studying interfacial interactions showed that the interfacial interactions of PVP with silica can be manipulated by varying the amounts of SDS and C(13)E(7) present. Upon SDS addition, the adsorbed layer thickness of PVP on silica increases due to Coulombic repulsion between micelles in the polymer layer. When C(13)E(7) is progressively added to the system, it forms mixed micelles with the complexed SDS, reducing the total charge per micelle and thus reducing the repulsion between micelle and the silica surface that would otherwise cause the PVP to desorb. This causes the amount of adsorbed polymer to increase with C(13)E(7) addition for the systems containing SDS, demonstrating that addition of C(13)E(7) hinders the SDS-mediated desorption of an adsorbed PVP layer. © 2012 American Chemical Society

  15. Flavonoid-surfactant interactions: A detailed physicochemical study

    Science.gov (United States)

    Singh, Onkar; Kaur, Rajwinder; Mahajan, Rakesh Kumar

    2017-01-01

    The aim of this article is to study the interactions between flavonoids and surfactants with attention of finding the probable location of flavonoids in micellar media that can be used for controlling their antioxidant behavior. In present study, the micellar and interfacial behavior of twin tailed anionic surfactants viz. sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP) in the presence of two flavonoids, namely quercetin (QUE) and kaempferol (KFL) have been studied by surface tension measurements. UV-visible, fluorescence and differential pulse voltammetric (DPV) measurements have been employed to predict the probable location of flavonoids (QUE/KFL) within surfactant (AOT/NaDEHP) aggregates. Dynamic light scattering (DLS) measurements further confirmed the solubilization of QUE/KFL in AOT/NaDEHP aggregates deduced from increased hydrodynamic diameter (Dh) of aggregates in the presence of flavonoids. Both radical scavenging activity (RSA) and degradation rate constant (k) of flavonoids are found to be higher in NaDEHP micelles as compared to AOT micelles.

  16. Degradation of Triton X-100 surfactant/lipid regulator systems by ionizing radiation in water

    International Nuclear Information System (INIS)

    Racz, Gergely; Obuda-University, Budapest; Csay, Tamas; Takacs, Erzsebet; Wojnarovits, Laszlo

    2017-01-01

    The radiolytic degradation of Triton X-100 surfactant was investigated at concentrations below and above the critical micelle concentration (CMC, ∼ 0.23 mmol dm -3 ) in air saturated aqueous solutions. At low concentrations the degradation took place both on the aromatic head and on the polyethoxylates chain, while above CMC it was shifted towards the chain. The CMC was higher in irradiated solutions at 10 Gy by a factor of 2, at 20 kGy by a factor of 3 than in the un-irradiated solution. The degradation of clofibric acid in the presence of TX-100 was more effective outside the micelles than inside them. (author)

  17. Single charging events on colloidal particles in a nonpolar liquid with surfactant

    Science.gov (United States)

    Schreuer, Caspar; Vandewiele, Stijn; Brans, Toon; Strubbe, Filip; Neyts, Kristiaan; Beunis, Filip

    2018-01-01

    Electrical charging of colloidal particles in nonpolar liquids due to surfactant additives is investigated intensively, motivated by its importance in a variety of applications. Most methods rely on average electrophoretic mobility measurements of many particles, which provide only indirect information on the charging mechanism. In the present work, we present a method that allows us to obtain direct information on the charging mechanism, by measuring the charge fluctuations on individual particles with a precision higher than the elementary charge using optical trapping electrophoresis. We demonstrate the capabilities of the method by studying the influence of added surfactant OLOA 11000 on the charging of single colloidal PMMA particles in dodecane. The particle charge and the frequency of charging events are investigated both below and above the critical micelle concentration (CMC) and with or without applying a DC offset voltage. It is found that at least two separate charging mechanisms are present below the critical micelle concentration. One mechanism is a process where the particle is stripped from negatively charged ionic molecules. An increase in the charging frequency with increased surfactant concentration suggests a second mechanism that involves single surfactant molecules. Above the CMC, neutral inverse micelles can also be involved in the charging process.

  18. Investigating Block-Copolymer Micelle Dynamics for Tunable Cargo Delivery

    Science.gov (United States)

    Li, Xiuli; Kidd, Bryce; Cooksey, Tyler; Robertson, Megan; Madsen, Louis

    Block-copolymer micelles (BCPMs) can carry molecular cargo in a nanoscopic package that is tunable using polymer structure in combination with cargo properties, as well as with external stimuli such as temperature or pH. For example, BCPMs can be used in targeted anticancer drug delivery due to their biocompatibility, in vivo degradability and prolonged circulation time. We are using NMR spectroscopy and diffusometry as well as SANS to investigate BCPMs. Here we study a diblock poly(ethylene oxide)-b-(caprolactone) (PEO-PCL) that forms spherical micelles at 1% (w/v) in the mixed solvent D2O/THF-d8. We quantify the populations and diffusion coefficients of coexisting micelles and free unimers over a range of temperatures and solvent compositions. We use temperature as a stimulus to enhance unimer exchange and hence trigger cargo release, in some cases at a few degrees above body temperature. We present evidence for dominance of the insertion-expulsion mechanism of unimer exchange in these systems, and we map phase diagrams versus temperature and solvent composition. This study sheds light on how intermolecular interactions fundamentally affect cargo release, unimer exchange, and overall micelle tunability.

  19. Responsive micellar films of amphiphilic block copolymer micelles: control on micelle opening and closing.

    Science.gov (United States)

    Chen, Zhiquan; He, Changcheng; Li, Fengbin; Tong, Ling; Liao, Xingzhi; Wang, Yong

    2010-06-01

    We reported the deliberate control on the micelle opening and closing of amphiphilic polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) micellar films by exposing them to selective solvents. We first treated the micellar films with polar solvents including ethanol and water (pH = 4, 8, and 12) that have different affinities to P2VP. We observed opening of the micelles in all the cases. Both the size of opened pores and the opening rate are dependent on the solvency of different solvents for P2VP. We then explored the closing behavior of the opened micelles using solvents having different affinities to PS. We found that the opened micelles were recovered to their initial closed micelle forms. The recovery was accompanied by a slow micelle disassociation process which gradually reduced the micelle size. The rates of the micelle closing and disassociation are also dependent on the solvency of different solvents for PS.

  20. Fluctuations of wormlike micelle fluids in capillary flow

    Science.gov (United States)

    Salipante, Paul; Meek, Stephen; Hudson, Steven; Polymers; Complex Fluids Group Team

    2017-11-01

    We investigate the effect of entrance geometry on the flow stability of wormlike micelles solutions in capillary flow. These solutions exhibit strong shear thinning behavior resulting from micelle breakage and have been observed to undergo large flow rate fluctuations. We investigate these fluctuations using simultaneous measurements of flow rate and pressure drop across a capillary, and we adjust entrance geometry. With a tapered constriction, we observe large persistent fluctuations above a critical flow rate, characterized by rapid decreases in the pressure drop with corresponding increase in flow rate followed by a period of recovery where pressure increases and flow rate decreases. Flow field observations in the tapered entrance show large flow circulations. An abrupt contraction produces smaller transient fluidized jets forming upstream of the constriction and the magnitude of the fluctuations are significantly diminished. The effect of fluid properties is studied by comparing the magnitude and timescales of the fluctuations for surfactant systems with different relaxation times. The onset of fluctuations is compared to a criterion for the onset of elastic instabilities and the magnitude is compared to estimates for changes in channel resistance. NIST on a Chip.

  1. Modification of shape oscillations of an attached bubble by surfactants

    Directory of Open Access Journals (Sweden)

    Tihon J.

    2013-04-01

    Full Text Available Surface-active agents (surfactants, e.g. washing agents strongly modifies properties of gas-liquid interface. We have carried out extensive experiments, in which we study effect of surfactants on the shape oscillations of a bubble, which is attached at a tip of a capillary. In the experiments, shape oscillations of a bubble are invoked by a motion of a capillary, to which the bubble is injected. Decaying oscillations are recorded and their frequency and damping are evaluated. By changing the excitation frequency, three lowest oscillation modes are studied. Experiments were repeated in aqueous solution of several surfactants (terpineol, SDS, CTAB, Triton X-100, Triton X-45 at various concentrations. Generally, these features are observed: Initially a surfactant addition leads to an increase of the oscillation frequency (though surface tension is decreasing; this effect can be attributed to the increasing interfacial elasticity. The decay time of oscillation is strongly decreasing, as a consequence of energy dissipation linked with Marangoni stresses. At a certain critical concentration, frequency decreases abruptly and the decay time passes by a minimum. With further addition of surfactant, frequency decreases, and the decay time slightly lengthens. Above critical micelle concentration, all these parameters stabilize. Interestingly, the critical concentration, at which frequency drop occurs, depends on mode order. This clearly shows that the frequency drop and minimum decay time are not a consequence of some abrupt change of interfacial properties, but are a consequence of some phenomena, which still need to be explained.

  2. Spectroscopic Analysis of 10MAG/LDAO Reverse Micelles to Determine Characteristic Properties and Behavioral Extrema

    Science.gov (United States)

    Berg, Joshua; Mawson, Cara; Norris, Zach; Nucci, Nathaniel

    Reverse micelles are spontaneously organizing complexes of surfactant that encapsulate a nanoscale pool of water in a bulk non-polar solvent. Reverse micelle (RM) mixtures have a wide range of applications, including biophysical investigation of protein systems. A new RM mixture composed of decyl-1-monoglycerol (10MAG) and lauryldimethylammonium-N-oxide (LDAO) was recently described. This mixture has the potential to prove more widely applicable for use of RMs in applications that involve encapsulation of macromolecules, yet little is known about the phase behavior or size of reverse micelles created by this mixture. Data describing such behaviors for this mixture are presented here. We have used dynamic light scattering (DLS) and fluorescence spectroscopy to investigate the size and partitioning behavior of RMs in varying mixtures of 10MAG, LDAO, water, pentane, and hexanol. These data demonstrate that the 10MAG/LDAO RM mixture exhibits markedly different phase and RM size behavior than that of commonly used RM surfactant mixtures. The implications of these findings for use of the 10MAG/LDAO mix for RM applications will also be addressed. Funding provided by Rowan University.

  3. Phase separation in solution of worm-like micelles: a dilute ? spin-vector model

    Science.gov (United States)

    Panizza, Pascal; Cristobal, Galder; Curély, Jacques

    1998-12-01

    We show how the dilute 0953-8984/10/50/006/img2 spin vector model introduced originally by Wheeler and co-workers for describing the polymerization phenomenon in solutions of liquid sulphur and of living polymers may be conveniently adapted for studying phase separation in systems containing long flexible micelles. We draw an isomorphism between the coupling constant appearing in the exchange Hamiltonian and the surfactant energies in the micellar problem. We solve this problem within the mean-field approximation and compare the main results we have obtained with respect to polymer theory and previous theories of phase separation in micellar solutions. We show that the attractive interaction term 0953-8984/10/50/006/img3 between monomers renormalizes the aggregation energy and subsequently the corresponding size distribution. Under these conditions, we observe that the general aspect of the phase diagram in the 0953-8984/10/50/006/img4 plane (where 0953-8984/10/50/006/img5 is the surfactant concentration) is different from previous results. The spinodal line shows a re-entrant behaviour and, at low concentrations, we point out the possibility of specific nucleation phenomena related to the existence of a metastable transition line between a region composed of spherical micelles and another one corresponding to a dilute solution of long flexible micelles.

  4. Enhancing fluorescence intensity of Ellagic acid in Borax-HCl-CTAB micelles

    Science.gov (United States)

    Wang, Feng; Huang, Wei; Zhang, Shuai; Liu, Guokui; Li, Kexiang; Tang, Bo

    2011-03-01

    Ellagic acid (C 14H 6O 8), a naturally occurring phytochemical, found mainly in berries and some nuts, has anticarcinogenic and antioxidant properties. It is found that fluorescence of Ellagic acid (EA) is greatly enhanced by micelle of cetyltrimethylammonium bromide (CTAB) surfactant. Based on this effect, a sensitive proposed fluorimetric method was applied for the determination of Ellagic acid in aqueous solution. In the Borax-HCl buffer, the fluorescence intensity of Ellagic acid in the presence of CTAB is proportional to the concentration of Ellagic acid in range from 8.0 × 10 -10 to 4.0 × 10 -5 mol L -1; and the detection limits are 3.2 × 10 -10 mol L -1 and 5.9 × 10 -10 mol L -1 excited at 266 nm and 388 nm, respectively. The actual samples of pomegranate rinds are simply manipulated and satisfactorily determined. The interaction mechanism studies argue that the negative EA-Borax complex is formed and solubilized in the cationic surfactant CTAB micelle in this system. The fluorescence intensity of EA enhances because the CTAB micelle provides a hydrophobic microenvironment for EA-Borax complex, which can prevent collision with water molecules and decrease the energy loss of EA-Borax complex.

  5. Photoreduction of viologen with (Zn-TPPS/sub 3/)/sup 3 -/. Triethanolamine- viologen system in the presence of micelles

    Energy Technology Data Exchange (ETDEWEB)

    Kita, Tatsuya; Okura, Ichiro

    1988-04-10

    Photoreduction of viologen was made in the presence of various surfactant micelles by irradading a trinary system of triethanol-amine, zinc meso-tetraphenylporphyrintrisulfonate ; (Zn-TPPS/sub 3/)/sup 3 -/, and viologen with the visible light. Although the rate of photoreduction of viologen was remarkably increased in the presence of either cationic or anionic micelles, it is not noticeably increased in the presence of neutral ones. The elementary reactions were measured by the laser flashing method. The elementary reactions were measured by the laser flashing method. The result indicates that the presence of ionic micelles retards both the quenching reaction of photoexcited (Zn-TPPS/sub 3/)/sup 3 -/ by viologen and the recombination reaction of the oxidative (Zn-TPPS/sub 3/)/sup 3 -/ with the reductive viologen and that the rate of reduction of viologen is much increased by the retardation of the recombination reaction. (6 figs, 1 tab, 16 refs)

  6. SP-A-enriched surfactant for treatment of rat lung transplants with SP-A deficiency after storage and reperfusion

    NARCIS (Netherlands)

    Erasmus, ME; Hofstede, GJH; Petersen, AH; Batenburg, JJ; Haagsman, HP; Oetomo, SB; Prop, J

    2002-01-01

    Background. The function of pulmonary surfactant is affected by lung transplantation, contributing to impaired lung transplant function. A decreased amount of surfactant protein-A (SP-A) after reperfusion is believed to contribute to the impaired surfactant function. Surfactant treatment has been

  7. Dynamic covalent surfactants

    NARCIS (Netherlands)

    Minkenberg, C.B.

    2012-01-01

    In this thesis the development of surfactant aggregates with fast exchange dynamics between the aggregated and non-aggregated state is described. Dynamic surfactant exchange plays an important role in natural systems, for instance in cell signaling, cell division, and uptake and release of cargo.

  8. Recombinant Amphiphilic Protein Micelles for Drug Delivery

    OpenAIRE

    Kim, Wookhyun; Xiao, Jiantao; Chaikof, Elliot L.

    2011-01-01

    Amphiphilic block polypeptides can self-assemble into a range of nanostructures in solution, including micelles and vesicles. Our group has recently described the capacity of recombinant amphiphilic diblock copolypeptides to form highly stable micelles. In this report, we demonstrate the utility of protein nanoparticles to serve as a vehicle for controlled drug delivery. Drug-loaded micelles were produced by encapsulating dipyridamole as a model hydrophobic drug with anti-inflammatory activit...

  9. Radiation-induced crosslinking of polymeric micelles as nanoparticle for immobilization of bioactive compound

    International Nuclear Information System (INIS)

    Rida Tajau; Khairul Zaman Mohd Dahlan; Mohd Hilmi Mahmood; Wan Md Zin Wan Yunus; Kamaruddin Hashim; Nor Azowa Ibrahim; Maznah Ismail; Mek Zah Salleh

    2012-01-01

    The purpose of this study was to develop the bioactive-loaded polymeric nanoparticle by radiation-induced crosslinking technique. The polymeric micelles consist of acrylated palm oil (APO), anionic surfactant and aqueous solution was prepared for immobilization of bioactive compound for example the Thymoquinone (TQ). The TQ-loaded APO micelle was subjected to ionizing radiation to induce crosslinked polymeric structure of the TQ-loaded APO nanoparticle. The formation of TQ-loaded APO micro micelle and nano particle were evaluated by the Dynamic Light Scattering (DLS), the Fourier Transform Infrared (FTIR) Spectroscopy and the Transmission Electron Microscopy (TEM) for characterization the size, the shape, the chemical structure and the irradiation effect of the micelle and the nano particle. The results indicate that the size of APO micro and nano particles varies from 120 to 270 nanometer (nm) upon gamma irradiation at doses ranging from 1 to 25 kilo gray (kGy). In addition, size of the particle was found decreasing upon irradiation due to the crosslinking interaction. The study demonstrated that the APO micro-and nanoparticle can retained and controlled the release rate of the thymoquinone at up to 24 hours as determined using ultraviolet-visible (UV-Vis) spectrophotometer. These findings suggested that the ionizing radiation method can be utilized to prepare nano-size APO particles, with the presence of TQ. (author)

  10. Structure of pure SDS and DTAB micelles in brine determined by small-angle neutron scattering (SANS)

    DEFF Research Database (Denmark)

    Bergström, M.; Pedersen, J.S.

    1999-01-01

    The geometrical structure of pure SDS and DTAB surfactant micelles in the absence of added salt as well as its dependence on the concentration of NaBr have been investigated at 40 degrees C using small-angle neutron scattering (SANS). In contrast to previous SANS measurements on the same systems we...... that ordinary surfactant micelles are shaped as circular or elongated bilayers (tablets). Both SDS and DTAB micelles appeared to be disk-like in pure D2O and the corresponding data were best fitted with a model for (monodisperse) oblate ellipsoids of revolution with half axes a=12.0 Angstrom, b=20.3 Angstrom...... ([SDS]=1.0 wt.%) and a=12.4 Angstrom, b=21.6 Angstrom ([DTAB]=1.0 wt.%). The half axis b related to the disk radius increases in both cases with an increasing amount of added salt to about 23 Angstrom (SDS) and 24 Angstrom (DTAB) at [NaBr]=0.1 M and at about [NaBr]=0.2 M the SDS micelles become tablet...

  11. Incomplete Loading of Sodium Lauryl Sulfate and Fasted State Simulated Intestinal Fluid Micelles Within the Diffusion Layers of Dispersed Drug Particles During Dissolution.

    Science.gov (United States)

    Galipeau, Kendra; Socki, Michael; Socia, Adam; Harmon, Paul A

    2018-01-01

    Poorly water soluble drug candidates have been common in developmental pipelines over the last several decades. This has fueled considerable research around understanding how bile salt and model micelles can improve drug particle dissolution rates and human drug exposure levels. However, in the pharmaceutical context only a single mechanism of how micelles load solute has been assumed, that being the direct loading mechanism put forth by Cussler and coworkers (Am Inst Chem Eng J. 1976;22(6):1006-1012) 40 years ago. In this model, micelles load at the particle surface and will be loaded to their equilibrium loading values. More recently, Kumar and Gandhi and coworkers (Langmuir. 2003;19:4014-4026) developed a comprehensive theory of micelle solubilization which also features an indirect loading mechanism which they argue should operate in ionic surfactant systems. In this mechanism, micelles cannot directly load at the solute particle surface and thus may not reach equilibrium loading values within the particle diffusion layer. In this work, we endeavor to understand if the indirect micelle loading mechanism represents a plausible description in the pharmaceutical context. The overall data in SLS and FaSSIF systems obtained here, as well as several other previously published datasets, can be described by the indirect micelle loading mechanism. Implications for pharmaceutical development of poorly soluble compounds are discussed. Copyright © 2018. Published by Elsevier Inc.

  12. Viscoelastic diamine surfactant for stable carbon dioxide/water foams over a wide range in salinity and temperature.

    Science.gov (United States)

    Elhag, Amro S; Da, Chang; Chen, Yunshen; Mukherjee, Nayan; Noguera, Jose A; Alzobaidi, Shehab; Reddy, Prathima P; AlSumaiti, Ali M; Hirasaki, George J; Biswal, Sibani L; Nguyen, Quoc P; Johnston, Keith P

    2018-07-15

    The viscosity and stability of CO 2 /water foams at elevated temperature can be increased significantly with highly viscoelastic aqueous lamellae. The slow thinning of these viscoelastic lamellae leads to greater foam stability upon slowing down Ostwald ripening and coalescence. In the aqueous phase, the viscoelasticity may be increased by increasing the surfactant tail length to form more entangled micelles even at high temperatures and salinity. Systematic measurements of the steady state shear viscosity of aqueous solutions of the diamine surfactant (C 16-18 N(CH 3 )C 3 N(CH 3 ) 2 ) were conducted at varying surfactant concentrations and salinity to determine the parameters for formation of entangled wormlike micelles. The apparent viscosity and stability of CO 2 /water foams were compared for systems with viscoelastic entangled micellar aqueous phases relative to those with much less viscous spherical micelles. We demonstrated for the first time stable CO 2 /water foams at temperatures up to 120 °C and CO 2 volumetric fractions up to 0.98 with a single diamine surfactant, C 16-18 N(CH 3 )C 3 N(CH 3 ) 2 . The foam stability was increased by increasing the packing parameter of the surfactant with a long tail and methyl substitution on the amine to form entangled viscoelastic wormlike micelles in the aqueous phase. The foam was more viscous and stable compared to foams with spherical micelles in the aqueous lamellae as seen with C 12-14 N(EO) 2 and C 16-18 N(EO)C 3 N(EO) 2 . Copyright © 2018. Published by Elsevier Inc.

  13. Thermodynamics on the micellization of various pure and mixed surfactants: Effects of head- and tail-groups

    International Nuclear Information System (INIS)

    Lee, Nam-Min; Lee, Byung-Hwan

    2016-01-01

    Highlights: • The values of critical micelle concentration of various pure and mixed surfactants are measured. • Thermodynamic parameters’ values are calculated to analyze the effects of head- and tail-groups on the micellization. • All the thermodynamic parameters’ values are decreasing with the increase of temperature. • The thermodynamic parameters’ values are depending severely on the chain length of alkyl group. - Abstract: The values of critical micelle concentration (CMC) for the micellization of various pure and mixed surfactants are determined by the UV–Vis spectrophotometric method. And the effects of temperature on the CMC values have been measured and thermodynamic parameters’ values are calculated to analyse the effects of head- and tail-groups on the micellization of surfactant molecules. The results show that the values of ΔG"o are negative and those of ΔS"o are positive for the micellization of all the surfactants within the measured temperature range. But the values of ΔH"o are positive or negative, depending on the kinds of surfactants. All these thermodynamic parameters’ values are decreasing together with the increase of temperature for all the surfactants. And these thermodynamic parameters’ values are depending severely on the chain length of alkyl group also as much as on the head-groups of surfactant molecules.

  14. Surfactant self-assembly in alcohol-rich solutions

    International Nuclear Information System (INIS)

    Bouguerra, N.; Jebari, M.M.; Gomati, R.; Gharbi, A.

    2005-01-01

    Ionic conductivity and viscosity measurements are achieved along alcohol dilution lines of a single-isotropic phase domain, which extends from the alcohol corner to sponge phase domain to brine corner, of an alcohol-surfactant-brine phase diagram. The results are discussed in terms of amphiphilic self-assembly which leads to stable mixtures of the slightly miscible alcohol and brine used. We show the formation of reverse micelles, whose cores are either dry or charged of brine according to the samples composition, and whose sizes remain small near the sponge phase structure

  15. Interaction between water-soluble rhodium complex RhCl(CO)(TPPTS)₂ and surfactants probed by spectroscopic methods.

    Science.gov (United States)

    Zhou, Li-Mei; Guo, Cai-Hong; Fu, Hai-Yan; Jiang, Xiao-Hui; Chen, Hua; Li, Rui-Xiang; Li, Xian-Jun

    2012-07-01

    The interactions of rhodium complex RhCl(CO)(TPPTS)(2) [TPPTS=P(m-C(6)H(4)SO(3)Na)(3)] with cationic, nonionic, and anionic surfactants have been investigated by UV-vis, fluorescence and (1)H NMR measurements. The presence of four different species of RhCl(CO)(TPPTS)(2) in cationic cetyltrimethylammonium (CTAB) solution has been demonstrated: free rhodium complex, rhodium complex bound to CTAB monomer, rhodium complex bound to CTAB premicelles, rhodium complex bound to CTAB micelles. The spectroscopy data show that RhCl(CO)(TPPTS)(2) can adsorb on the interface of cationic CTAB micelles by strong electrostatic attraction, weakly bind to the nonionic polyoxyethylene (20) sorbitan monolaurate (Tween 20) micelles by hydrophobic interaction, and does not interact with anion sodium dodecyl sulfate (SDS) micelles due to the strong electrostatic repulsion. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Mixed reverse micelles facilitated downstream processing of lipase involving water-oil-water liquid emulsion membrane.

    Science.gov (United States)

    Bhowal, Saibal; Priyanka, B S; Rastogi, Navin K

    2014-01-01

    Our earlier work for the first time demonstrated that liquid emulsion membrane (LEM) containing reverse micelles could be successfully used for the downstream processing of lipase from Aspergillus niger. In the present work, we have attempted to increase the extraction and purification fold of lipase by using mixed reverse micelles (MRM) consisting of cationic and nonionic surfactants in LEM. It was basically prepared by addition of the internal aqueous phase solution to the organic phase followed by the redispersion of the emulsion in the feed phase containing enzyme, which resulted in globules of water-oil-water (WOW) emulsion for the extraction of lipase. The optimum conditions for maximum lipase recovery (100%) and purification fold (17.0-fold) were CTAB concentration 0.075 M, Tween 80 concentration 0.012 M, at stirring speed of 500 rpm, contact time 15 min, internal aqueous phase pH 7, feed pH 9, KCl concentration 1 M, NaCl concentration 0.1 M, and ratio of membrane emulsion to feed volume 1:1. Incorporation of the nonionic surfactant (e.g., Tween 80) resulted in remarkable improvement in the purification fold (3.1-17.0) of the lipase. LEM containing a mixture of nonionic and cationic surfactants can be successfully used for the enhancement in the activity recovery and purification fold during downstream processing of enzymes/proteins. © 2014 American Institute of Chemical Engineers.

  17. Evaporation kinetics of surfactant solution droplets on rice (Oryza sativa) leaves

    Science.gov (United States)

    Cao, Li-Dong; Zheng, Li; Xu, Jun; Li, Feng-Min; Huang, Qi-Liang

    2017-01-01

    The dynamics of evaporating sessile droplets on hydrophilic or hydrophobic surfaces is widely studied, and many models for these processes have been developed based on experimental evidence. However, few research has been explored on the evaporation of sessile droplets of surfactant or pesticide solutions on target crop leaves. Thus, in this paper the impact of surfactant concentrations on contact angle, contact diameter, droplet height, and evolution of the droplets’ evaporative volume on rice leaf surfaces have been investigated. The results indicate that the evaporation kinetics of surfactant droplets on rice leaves were influenced by both the surfactant concentrations and the hydrophobicity of rice leaf surfaces. When the surfactant concentration is lower than the surfactant CMC (critical micelle concentration), the droplet evaporation time is much longer than that of the high surfactant concentration. This is due to the longer existence time of a narrow wedge region under the lower surfactant concentration, and such narrow wedge region further restricts the droplet evaporation. Besides, our experimental data are shown to roughly collapse onto theoretical curves based on the model presented by Popov. This study could supply theoretical data on the evaporation of the adjuvant or pesticide droplets for practical applications in agriculture. PMID:28472108

  18. Structural study of concentrated micelle-solutions of sodium octanoate by light scattering

    International Nuclear Information System (INIS)

    Hayoun, Marc

    1982-05-01

    Structural investigation of sodium octanoate (CH 3 -(CH 2 ) 6 -COONa) by light scattering has been made to study properties of concentrated aqueous micelle-solutions. From static light scattering data, the micellar weight and shape have been determined. The monomer aggregation number and the apparent micellar charge have been confirmed. Quasi-elastic light scattering, has been used to measure the effective diffusion coefficient as a function of the volume fraction. Extrapolation to the c.m.c. give the hydrodynamic radius of the micelles. At low micelle-concentration, strong exchange reaction between monomers and micelles affects the Brownian motion and resulting is an increase in the diffusion coefficient. The experimental data show a strong hydrodynamic contribution to S(q) (factor structure) and D(q) (effective diffusion coefficient) arising from hard spheres interactions with a large repulsive potential. (author) [fr

  19. Micelle-stabilized room-temperature phosphorescence with synchronous scanning

    International Nuclear Information System (INIS)

    Femia, R.A.; Love, L.J.C.

    1984-01-01

    The experimental requirements for synchronous wavelength scanning micelle-stabilized room temperature phosphorescence and the factors affecting peak resolution are presented and compared with those for synchronous wavelength scanning fluorescence. Identification of individual compounds in a four-component mixture is illustrated, and criteria to identify and minimize triplet state energy transfer are given. Considerable improvement in resolution of the synchronous peaks is obtained via second derivative spectra. 20 references, 7 figures, 2 tables

  20. Optimization of protein extraction process from jackfruit seed flour by reverse micelle system

    Directory of Open Access Journals (Sweden)

    Maycon Fagundes Teixeira Reis

    2016-06-01

    Full Text Available The extraction of protein from flour of jackfruit seeds by reverse micelles was evaluated. Reverse micelle system was composed of sodium dodecyl sulfate (SDS as surfactant, butanol as solvent, and water. The effects of stirring time, temperature, molar ratio H2O SDS-1, concentration of butanol (mass percentage and flour mass were tested in batch systems. Based on the adjusted linear regression model, only butanol concentration provided optimum extraction conditions (41.16%. Based on the analysis of surface response, the best extraction yield could be obtained at 25°C, stirring time of 120 min, mass of flour of 100 mg, and a ratio H2O SDS-1 of 50. Experimental results showed that a 79.00% extraction yield could be obtained.

  1. Microencapsulation of superoxide dismutase into poly(epsilon-caprolactone) microparticles by reverse micelle solvent evaporation.

    Science.gov (United States)

    Youan, Bi-Botti Célestin

    2003-01-01

    The aim of this work was to encapsulate superoxide dismutase (SOD) in poly(epsilon-caprolactone) (PCL) microparticles by reverse micelle solvent evaporation. The concentration of PCL, the hydrophile-lipophile balance (HLB), and concentration of the sucrose ester used as surfactant in the organic phase were investigated as formulation variables. Relatively higher encapsulation efficiency (approximately 48%) and retained enzymatic activity (>90%) were obtained with microparticle formulation made from the 20% (w/v) PCL and 0.05% (w/v) sucrose ester of HLB = 6. This formulation allowed the in vitro release of SOD for at least 72 hr. These results showed that reverse micelle solvent evaporation can be used to efficiently encapsulate SOD in PCL microparticles. Such formulations may improve the bioavailability of SOD.

  2. Structure factor of polymers interacting via a short range repulsive potential: Application to hairy wormlike micelles

    International Nuclear Information System (INIS)

    Massiera, Gladys; Ramos, Laurence; Ligoure, Christian; Pitard, Estelle

    2003-01-01

    We use the random phase approximation to compute the structure factor S(q) of a solution of chains interacting through a soft and short range repulsive potential V. Above a threshold polymer concentration, whose magnitude is essentially controlled by the range of the potential, S(q) exhibits a peak whose position depends on the concentration. We take advantage of the close analogy between polymers and wormlike micelles and apply our model, using a Gaussian function for V, to quantitatively analyze experimental small angle neutron scattering profiles of solutions of hairy wormlike micelles. These samples, which consist in surfactant self-assembled flexible cylinders decorated by amphiphilic copolymer, provide indeed an appropriate experimental model system to study the structure of sterically interacting polymer solutions

  3. Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis

    Science.gov (United States)

    Martino, Anthony; Yamanaka, Stacey A.; Kawola, Jeffrey S.; Showalter, Steven K.; Loy, Douglas A.

    1998-01-01

    A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5-10 nm in diameter with a monodisperse size distribution.

  4. Pulmonary surfactant and lung transplantation

    NARCIS (Netherlands)

    Erasmus, Michiel Elardus

    1997-01-01

    Pulmonary surfactant lowers the surface tension at the air-water interface inside the alveolus. This is achieved by adsorption of surfactant phospholipids at the air-water interface, a process controlled by surfactant-associated proteins, such as SP-A. In this way, surfactant prevents collapse of

  5. Micellization and microstructural studies between amphiphilic drug ibuprofen with non-ionic surfactant in aqueous urea solution

    International Nuclear Information System (INIS)

    Rub, Malik Abdul; Azum, Naved; Kumar, Dileep; Asiri, Abdullah M.; Marwani, Hadi M.

    2014-01-01

    Highlights: • Micellization behavior of (ibuprofen + non-ionic surfactant) mixtures has been investigated. • Ion–dipole type of interaction between ibuprofen drug and non-ionic surfactant. • The negative β values propose attractive interactions between the components. • Stern–Volmer binding constants (K sv ) and dielectric constant of mixed systems have also been evaluated. • The results have applicability in drug delivery. - Abstract: Herein, we have accounted for the interaction between a non-steroidal anti-inflammatory drug ibuprofen (IBF) and non-ionic surfactant polyethoxyglycol t-octylphenyl ether (TX-100 (4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol) and TX-114 ((1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol)), in aqueous urea solutions using tensiometric and fluorimetric techniques at T = 298.15 K. Surface tension measurements were carried out to evaluate the critical micelle concentrations (cmc) of the drug and surfactant as well as their mixtures of varying compositions. An increase in the surface charge of the micelles was observed with the addition of urea followed by halt of micelles formation. Various physicochemical parameters, such as, cmc values of the mixture, micellar mass fraction (X 1 Rub ) of surfactants (TX-100/TX-114), interaction parameters (β) at the monolayer air–water interface and in bulk solutions, different thermodynamic parameters and activity coefficients (f 1 m ,f 2 m ) for the non-ionic surfactant and drug in the mixed micelles, were determined by using the approach of Clint, of Rubingh, and of Rosen. All results identified synergism and attractive interactions in the mixed systems of (drug–surfactant) mixtures and showed effective involvement of the non-ionic surfactant (TX-100/TX-114) component in the mixture. Micelle aggregation numbers (N agg ), evaluated by using steady-state fluorescence quenching studies, suggest that the contribution of non-ionic surfactant was always more than that of

  6. Photochemical key steps in the synthesis of surfactants from furfural-derived intermediates.

    Science.gov (United States)

    Gassama, Abdoulaye; Ernenwein, Cédric; Hoffmann, Norbert

    2009-01-01

    Furfural is oxidized to 2[5H]-furanone by using hydrogen peroxide or to 5-hydroxy-2[5H]-furanone by using photo-oxygenation. An amine function is introduced by photochemically induced radical addition of tertiairy amines, some of which carry an n-alkyl side chain as hydrophobic moiety. These amines are produced from fatty aldehydes and cyclic secondary amines. The resulting adducts are transformed into amphoteric surfactants possessing an ammonium and a carboxylate function. Amphoteric (pK(N) and isoelectric point) and surfactant properties such as the critical micelle concentration and the adsorption efficiency are determined.

  7. Vibrational dynamics of ice in reverse micelles

    NARCIS (Netherlands)

    Dokter, A.M.; Petersen, C.; Woutersen, S.; Bakker, H.J.

    2008-01-01

    he ultrafast vibrational dynamics of HDO:D2O ice at 180 K in anionic reverse micelles is studied by midinfrared femtosecond pump-probe spectroscopy. Solutions containing reverse micelles are cooled to low temperatures by a fast-freezing procedure. The heating dynamics of the micellar solutions is

  8. Molecular organization and dynamics of micellar phase of polyelectrolyte-surfactant complexes: ESR spin probe study

    Science.gov (United States)

    Wasserman, A. M.; Kasaikin, V. A.; Zakharova, Yu. A.; Aliev, I. I.; Baranovsky, V. Yu.; Doseva, V.; Yasina, L. L.

    2002-04-01

    Molecular dynamics and organization of the micellar phase of complexes of linear polyelectrolytes with ionogenic and non-ionogenic surfactants was studied by the ESR spin probe method. Complexes of polyacrylic acid (PAA) and sodium polystyrenesulfonate (PSS) with alkyltrimethylammonium bromides (ATAB), as well as complexes of poly- N, N'-dimethyldiallylammonium chloride (PDACL) with sodium dodecylsulfate (SDS) were studied. The micellar phase of such complexes is highly organized molecular system, molecular ordering of which near the polymeric chain is much higher than in the 'center' of the micelle, it depends on the polymer-detergent interaction, flexibility of polymeric chain and length of carbonic part of the detergent molecule. Complexes of polymethacrylic acid (PMAA) with non-ionic detergent (dodecyl-substituted polyethyleneglycol), show that the local mobility of surfactant in such complexes is significantly lower than in 'free' micelles and depends on the number of micellar particles participating in formation of complexes.

  9. Structure of modified [epsilon]-polylysine micelles and their application in improving cellular antioxidant activity of curcuminoids

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hailong; Li, Ji; Shi, Ke; Huang, Qingrong (Rutgers)

    2015-10-15

    The micelle structure of octenyl succinic anhydride modified {var_epsilon}-polylysine (M-EPL), an anti-microbial surfactant prepared from natural peptide {var_epsilon}-polylysine in aqueous solution has been studied using synchrotron small-angle X-ray scattering (SAXS). Our results revealed that M-EPLs formed spherical micelles with individual size of 24-26 {angstrom} in aqueous solution which could further aggregate to form a larger dimension with averaged radius of 268-308 {angstrom}. Furthermore, M-EPL micelle was able to encapsulate curcuminoids, a group of poorly-soluble bioactive compounds from turmeric with poor oral bioavailability, and improve their water solubility. Three loading methods, including solvent evaporation, dialysis, and high-speed homogenization were compared. The results indicated that the dialysis method generated the highest loading capacity and curcuminoids water solubility. The micelle encapsulation was confirmed as there were no free curcuminoid crystals detected in the differential scanning calorimetry analysis. It was also demonstrated that M-EPL encapsulation stabilized curcuminoids against hydrolysis at pH 7.4 and the encapsulated curcuminoids showed elevated cellular antioxidant activity compared with free curcuminoids. This work suggested that M-EPL could be used as new biopolymer micelles for delivering poorly soluble drugs/phytochemicals and improving their bioactivities.

  10. Lowering of the critical concentration for micelle formation in aqueous soap solutions by action of truly dissolved hydrocarbon at various temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Markina, Z.N.; Kostova, N.Z.; Rebinder, P.A.

    1970-03-01

    The effect of dissolved hydrocarbons (octane, benzene, and ethylbenzene) on critical micelle concentration of aqueous solutions of sodium salts of fatty acids from caproate to sodium myristate at various temperatures was studied. Experimental results showed that formation of micelles is promoted by presence of hydrocarbons dissolved in the water phase. Such solutions have below normal critical micelle concentration. The change in critical micelle concentration decreases with increase in length of hydrocarbon chain in the soap molecule and with decrease of hydrocarbon solubility in pure water. The nature of the hydrocarbon also affects the forms and dimension of the micelle. Aromatic hydrocarbons increase micelle volume and greatly decrease C.M.C., while aliphatic hydrocarbons decrease C.M.C. slightly. (12 refs.)

  11. Micelle size modulation and phase behavior in MEGA-10/Triton X-100 mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Naous, M., E-mail: elzahraadz@yahoo.fr; Molina-Bolívar, J.A.; Ruiz, C. Carnero, E-mail: ccarnero@uma.es

    2014-12-20

    Highlights: • The size of micelles was studied as a function of the micellar composition, NaCl addition and temperature. • Cloud point can be modulated by changing both micellar composition and NaCl addition. • The energetic quantities at the cloud point were evaluated and discussed. - Abstract: This paper reports the effect of temperature and NaCl addition on micelle size and phase behavior in mixtures of N-decanoyl-N-methylglucamide (MEGA-10) and p-tert-octyl-phenoxy polyethylene (9.5) ether (Triton X-100 or TX100). The size of mixed micelles, as determined by dynamic light scattering (DLS), was found to increase with temperature but to be less pronounced at higher proportions of MEGA-10 in the solution. The cloud point was found to increase with an initial increase in the percentage of sugar-based surfactant in the mixture. This phase separation was sensitive to the presence of NaCl in the micellar solution, which induced a cloud point depression, thereby suggesting that the presence of electrolyte produces a marked alteration of the hydration layer of micelles. A thermodynamic analysis was performed assuming the clouding phenomenon to be a liquid–liquid phase-separation process. The resulting ΔG{sub CP}{sup 0} values were positive for all solutions. The cloud point process was exothermic in nature for the mixed micellar system, as proven by the negative value of ΔH{sub CP}{sup 0}. The process was more exothermic as the proportion of sugar-based surfactant in the mixed micelle increased (with and without NaCl in the solution). Furthermore, the negative values of ΔS{sub CP}{sup 0} indicate that the association of micelles in the clouding phenomenon is entropically unfavorable. It was observed from the enthalpy–temperature plots that the change in heat capacity is negative, thus indicating the important role played by dehydration in this thermodynamic process. This study found that the enthalpy–entropy compensation relationship holds for this

  12. Extraction and Characterization of Surfactants from Atmospheric Aerosols.

    Science.gov (United States)

    Nozière, Barbara; Gérard, Violaine; Baduel, Christine; Ferronato, Corinne

    2017-04-21

    Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in the Earth's atmosphere, a central process in meteorology, hydrology, and for the climate system. But because specific extraction and characterization of these compounds have been lacking for decades, very little is known on their identity, properties, mode of action and origins, thus preventing the full understanding of cloud formation and its potential links with the Earth's ecosystems. In this paper we present recently developed methods for 1) the targeted extraction of all the surfactants from atmospheric aerosol samples and for the determination of 2) their absolute concentrations in the aerosol phase and 3) their static surface tension curves in water, including their Critical Micelle Concentration (CMC). These methods have been validated with 9 references surfactants, including anionic, cationic and non-ionic ones. Examples of results are presented for surfactants found in fine aerosol particles (diameter <1 μm) collected at a coastal site in Croatia and suggestions for future improvements and other characterizations than those presented are discussed.

  13. Polymeric microcapsules assembled from a cationic/zwitterionic pair of responsive block copolymer micelles.

    Science.gov (United States)

    Addison, Timothy; Cayre, Olivier J; Biggs, Simon; Armes, Steven P; York, David

    2010-05-04

    Using a layer-by-layer (LbL) approach, this work presents the preparation of hollow microcapsules with a membrane constructed entirely from a cationic/zwitterionic pair of pH-responsive block copolymer micelles. Our previous work with such systems highlighted that, in order to retain the responsive nature of the individual micelles contained within the multilayer membranes, it is important to optimize the conditions required for the selective dissolution of the sacrificial particulate templates. Consequently, here, calcium carbonate particles have been employed as colloidal templates as they can be easily dissolved in aqueous environments with the addition of chelating agents such as ethylenediaminetetraacetic acid (EDTA). Furthermore, the dissolution can be carried out in solutions buffered to a desirable pH so not to adversely affect the pH sensitive micelles forming the capsule membranes. First, we have deposited alternating layers of anionic poly[2-(dimethylamino)ethyl methacrylate-block-poly(2-(diethylamino)ethyl methacrylate)] (PDMA-PDEA) and cationic poly(2-(diethylamino)ethyl)methacrylate-block-poly(methacrylic acid) (PDEA-PMAA) copolymer micelles onto calcium carbonate colloidal templates. After deposition of five micelle bilayers, addition of dilute EDTA solution resulted in dissolution of the calcium carbonate and formation of hollow polymer capsules. The capsules were imaged using atomic force microscopy (AFM) and scanning electron microscopy (SEM), which shows that the micelle/micelle membrane is sufficiently robust to withstand dissolution of the supporting template. Quartz crystal microbalance studies were conducted and provide good evidence that the micelle multilayer structure is retained after EDTA treatment. In addition, a hydrophobic dye was incorporated into the micelle cores prior to adsorption. After dissolution of the particle template, the resulting hollow capsules retained a high concentration of dye, suggesting that the core

  14. Dilute Surfactant Methods for Carbonate Formations

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2006-02-01

    There are many fractured carbonate reservoirs in US (and the world) with light oil. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). The process of using dilute anionic surfactants in alkaline solutions has been investigated in this work for oil recovery from fractured oil-wet carbonate reservoirs both experimentally and numerically. This process is a surfactant-aided gravity drainage where surfactant diffuses into the matrix, lowers IFT and contact angle, which decrease capillary pressure and increase oil relative permeability enabling gravity to drain the oil up. Anionic surfactants have been identified which at dilute concentration of 0.05 wt% and optimal salinity can lower the interfacial tension and change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil. The force of adhesion in AFM of oil-wet regions changes after anionic surfactant treatment to values similar to those of water-wet regions. The AFM topography images showed that the oil-wetting material was removed from the surface by the anionic surfactant treatment. Adsorption studies indicate that the extent of adsorption for anionic surfactants on calcite minerals decreases with increase in pH and with decrease in salinity. Surfactant adsorption can be minimized in the presence of Na{sub 2}CO{sub 3}. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (20-42% OOIP in 50 days; up to 60% in 200 days) for initially oil-wet cores through wettability alteration and IFT reduction. Small (<10%) initial gas saturation does not affect significantly the rate of oil recovery in the imbibition process, but larger gas saturation decreases the oil recovery rate. As the core permeability decreases, the rate of oil recovery reduces

  15. Adsorption of dissymmetric cationic gemini surfactants at silica/water interface

    Science.gov (United States)

    Sun, Yuhai; Feng, Yujun; Dong, Hongwei; Chen, Zhi

    2007-05-01

    Adsorption of a series of cationic gemini surfactants 12-2- m ( m = 8, 12, 16) on the surface of silica was investigated. The critical micelle concentrations, cmcs, of cationic gemini surfactants in the initial solutions and in the supernatants were measured by conductometry and tensiometer. The changes in cmc values indicate that the ion exchanges take place between polar groups of gemini surfactants adsorbed and ions bound on the surface of silica. The adsorption isotherms of cationic gemini surfactants were obtained by a solution depletion method. Based on the driving force, the adsorption includes two steps, one of which is ion exchange, and the other is hydrophobic interaction. In each step, the tendency of surfactant molecules in the solution to form aggregates or to be adsorbed on the silica varies with their structures. The maximum adsorption amount of gemini surfactants on the silica, τmax, decreases as increasing in the length of one alkyl chain, m, from 8, 12 to 16. So the results show that the adsorption behaviors of gemini surfactants are closely related to the dissymmetry of gemini molecules.

  16. Surfactant-adsorption-induced initial depinning behavior in evaporating water and nanofluid sessile droplets.

    Science.gov (United States)

    Zhong, Xin; Duan, Fei

    2015-05-19

    A surfactant-induced autophobic effect has been observed to initiate an intense depinning behavior at the initial stage of evaporation in both pure water and nanofluid sessile droplets. The cationic surfactant adsorbing to the negatively charged silicon wafer makes the solid surface more hydrophobic. The autophobing-induced depinning behavior, leading to an enlarged contact angle and a shortened base diameter, takes place only when the surfactant concentration is below its critical micelle concentration (cmc). The initial spreading degree right before the droplet retraction, the retracting velocity of the contact line, and the duration of the initial droplet retraction are shown to depend negatively on the surfactant concentration below the cmc. An unexpected enhancement in the initial depinning has been found in the nanofluid droplets, possibly resulting from the hydrophilic interplay between the graphite nanoparticle deposition and the surfactant molecules. Such promotion of the initial depinning due to the nanoparticle deposition makes the droplet retract even at a surfactant concentration higher than the cmc (1.5 cmc). The resulting deposition formed in the presence of the depinning behavior has great enhancement for coffee-ring formation as compared to the one free of surfactant, implying that the formation of a coffee ring does not require the pinning of the contact line during the entire drying process.

  17. Surfactant-Enhanced Size-Excluded Transport of Bacteria Through Unsaturated Porous Media.

    Science.gov (United States)

    Zhu, J.

    2017-12-01

    US domestic waste water is rich in surfactants because of the intensive usage of surfactants-containing household product. It results in a surfactants presence environment when this untreated waste water released into subsurface. It was reported that surfactants enhance the colloidal transport in porous media, which have significant effect on issues such as subsurface pathogens contamination and biodegradation. In this study, soil column experiments were conducted. The soil column was remained unsaturated and with a steady flow passing through it. Escherichia coli K-12 transported in the soil column and its breakthrough data was collected in presence of surfactant anionic surfactant linear alkylbenzene sulfonate (LAS) concentration range over 0, 0.25, 0.5, 0.75, 1, and 2 times Critical Micelle Concentration (CMC). It was found that the increase in LAS concentration greatly increases breakthrough concentration C/C0 and decreases breakthrough time tb until LAS concentration reaches 1 xCMC. Numerical models were built simulating and investigating this phenomenon. The goodness of model fitting was greatly improved by adding exclusion factor into the model, which indicated that the presence of surfactant might enhance the exclusion effect. The relationships between LAS concentration and the two coefficients, deposition rate coefficient k and exclusion effect coefficient θim, were found can be fitted by a quasi-Langmuir equation. And the model validation with observed data showed that the model has an acceptable reliability.

  18. Casein Micelle Dispersions under Osmotic Stress

    Science.gov (United States)

    Bouchoux, Antoine; Cayemitte, Pierre-Emerson; Jardin, Julien; Gésan-Guiziou, Geneviève; Cabane, Bernard

    2009-01-01

    Abstract Casein micelles dispersions have been concentrated and equilibrated at different osmotic pressures using equilibrium dialysis. This technique measured an equation of state of the dispersions over a wide range of pressures and concentrations and at different ionic strengths. Three regimes were found. i), A dilute regime in which the osmotic pressure is proportional to the casein concentration. In this regime, the casein micelles are well separated and rarely interact, whereas the osmotic pressure is dominated by the contribution from small residual peptides that are dissolved in the aqueous phase. ii), A transition range that starts when the casein micelles begin to interact through their κ-casein brushes and ends when the micelles are forced to get into contact with each other. At the end of this regime, the dispersions behave as coherent solids that do not fully redisperse when osmotic stress is released. iii), A concentrated regime in which compression removes water from within the micelles, and increases the fraction of micelles that are irreversibly linked to each other. In this regime the osmotic pressure profile is a power law of the residual free volume. It is well described by a simple model that considers the micelle to be made of dense regions separated by a continuous phase. The amount of water in the dense regions matches the usual hydration of proteins. PMID:19167314

  19. Casein micelle structure: a concise review

    Directory of Open Access Journals (Sweden)

    Chanokphat Phadungath

    2005-01-01

    Full Text Available Milk is a complex biological fluid with high amount of proteins, lipid and minerals. The function of milk is to supply nutrients such as essential amino acids required for the growth of the newborn. In addition, due to the importance of casein and casein micelles for the functional behavior of dairy products, the nature and structure of casein micelles have been studied extensively. However, the exact structure of casein micelles is still under debate. Various models for casein micelle structure have been proposed. Most of the proposedmodels fall into three general categories, which are: coat-core, subunit (sub-micelles, and internal structure models. The coat-core models, proposed by Waugh and Nobel in 1965, Payens in 1966, Parry and Carroll in 1969, and Paquin and co-workers in 1987, describe the micelle as an aggregate of caseins with outer layer differing in composition form the interior, and the structure of the inner part is not accurately identified. The sub-micelle models, proposed by Morr in 1967, Slattery and Evard in 1973, Schmidt in 1980, Walstra in1984, and Ono and Obata in 1989, is considered to be composed of roughly spherical uniform subunits. The last models, the internal structure models, which were proposed by Rose in 1969, Garnier and Ribadeau- Dumas in 1970, Holt in 1992, and Horne in 1998, specify the mode of aggregation of the different caseins.

  20. Impact of model perfume molecules on the self-assembly of anionic surfactant sodium dodecyl 6-benzene sulfonate.

    Science.gov (United States)

    Bradbury, Robert; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Jones, Craig; Grillo, Isabelle

    2013-03-12

    The impact of two model perfumes with differing degrees of hydrophobicity/hydrophilicity, linalool (LL) and phenylethanol (PE), on the solution structure of anionic surfactant sodium dodecyl 6-benzene sulfonate, LAS-6, has been studied by small angle neutron scattering, SANS. For both types of perfume molecules, complex phase behavior is observed. The phase behavior depends upon the concentration, surfactant/perfume composition, and type of perfume. The more hydrophilic perfume PE promotes the formation of more highly curved structures. At relatively low surfactant concentrations, small globular micelles, L1, are formed. These become perfume droplets, L(sm), stabilized by the surfactant at much higher perfume solution compositions. At higher surfactant concentrations, the tendency of LAS-6 to form more planar structures is evident. The more hydrophobic linalool promotes the formation of more planar structures. Combined with the greater tendency of LAS-6 to form planar structures, this results in the planar structures dominating the phase behavior for the LAS-6/linalool mixtures. For the LAS-6/linalool mixture, the self-assembly is in the form of micelles only at the lowest surfactant and perfume concentrations. Over most of the concentration-composition space explored, the structures are predominantly lamellar, L(α), or vesicle, L(v), or in the form of a lamellar/micellar coexistence. At low and intermediate amounts of LL, a significantly different structure is observed, and the aggregates are in the form of small, relatively monodisperse vesicles (i.e., nanovesicles), L(sv).

  1. BEHAVIOR OF SURFACTANT MIXTURE AT SOLID/LIQUID AND OIL/LIQUID INTERFACE IN CHEMICAL FLOODING SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Prof. P. Somasundaran

    2002-03-01

    The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Preliminary ultra-filtration tests suggest that two kinds of micelles may exist in binary surfactant mixtures at different concentrations. Due to the important role played in interfacial processes by micelles as determined by their structures, focus of the current work is on the delineation of the relationship between such aggregate structures and chemical compositions of the surfactants. A novel analytical centrifuge application is explored to generate information on structures of different surfactants aggregates. In this report, optical systems, typical output of the analytical ultracentrifuge results and four basic experiments are discussed. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. The partial specific volume was calculated to be 0.920. Four softwares: Optima{trademark} XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity experimental data. The sedimentation coefficient and aggregation number of NP-10 micelles obtained using the first three softwares at 25 C are 209, 127, and 111, respectively. The last one is closest to the result from Light Scattering. The reason for the differences in numbers obtained using the three softwares is discussed. Based on these tests, Svedberg and SEDFIT analysis are chosen for further studies. This approach using the analytical ultracentrifugation offers an unprecedented opportunity now to obtain important information on mixed micelles and their role in interfacial processes.

  2. Identifying the Imprint of Surfactant Stabilisation in Whitecap Foam Evolution

    Science.gov (United States)

    Callaghan, A. H.; Deane, G. B.; Stokes, D.

    2016-02-01

    Surfactants are ubiquitous in the world's oceans and can affect climatically-relevant processes such as air-sea gas exchange, sea spray aerosol (SSA) flux, and air-sea momentum transfer. Surfactants are amphiphilic and help form the physically and chemically distinct ocean surface microlayer (SML), however, the spatial distribution, concentration and composition of the SML is not well understood, especially under conditions of vigorous wave breaking. Like the SML, breaking waves also influence physical exchange processes at the air-sea interface, and oceanic whitecap foam coverage is commonly used to quantify bubble-mediated exchange processes. However, surfactants can increase the lifetime of foam over clean water conditions, potentially complicating the use of whitecap coverage to parameterise air-sea gas exchange and SSA production flux. A better understanding of how surfactants affect the evolution of whitecap foam is needed to improve whitecap parameterisations of bubble-mediated processes, and may also provide a remote sensing approach to map the spatial distribution of surfactants at the water surface. Here we present results from a laboratory study that looked at whitecap foam evolution in "clean" and "surfactant-added" seawater regimes. We find that the whitecap foam area growth timescale is largely insensitive to the presence of surfactants, but that surfactant stabilization of whitecap foam becomes important during the whitecap foam area decay phase. The timescale at which this occurs appears to be consistent for breaking waves of different scale and intensity. A simple method is then used to isolate the surfactant signal and derive an equivalent "clean" seawater foam decay time for the whitecaps in the "surfactant-added" regime. The method is applied to oceanic whitecaps and results compared to the laboratory whitecaps from the "clean" and "surfactant-added" regimes.

  3. BINDING OF IONIC SURFACTANTS ON OPPOSITELY CHARGED POLYELECTROLYTES OBSERVED BY FLUORESCENCE METHODS

    Institute of Scientific and Technical Information of China (English)

    Zhen Tong; Chao-yang Wang; Bi-ye Ren; Xin-xing Liu; Fang Zeng

    2003-01-01

    Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observed with fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB),dodecyltrimethylammonium chloride (DTAC), and nonionic surfactant octaethylene glycol monododecyl ether (C12E8) were allowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalene labeled copolymers. The relative excimer emission intensity IE/IM of a cationic probe 1-pyrenemethylamine hydrochloride were chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes. The 1:1aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightly higher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-bound polyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither 1:1polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to its weaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescence results, nonionic surfactant C12E8 did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted the micelle formation for C12E8 at the CAC slightly below its critical micelle concentration (CMC). The solid complex of dansyl labeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of the polyelectrolyte or with alkane tail length of the surfactant. SAXS suggested a lamella structure for the AMPS copolymersurfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively.

  4. Mixed system of ionic liquid and non-ionic surfactants in aqueous media: Surface and thermodynamic properties

    International Nuclear Information System (INIS)

    Bhatt, Darshak; Maheria, Kalpana; Parikh, Jigisha

    2014-01-01

    Highlights: • Interaction of ionic liquid and ethylene oxide based non-ionic surfactants in aqueous media. • Evaluation of various surface properties and thermodynamic parameters. • Micellar growth ensues from exothermic to endothermic with increase in temperature. • Micelle formation is enthalpy driven at low temperature and entropy driven at higher temperature. • The micellization power and adsorption proficiency decreased at high IL concentrations. - Abstract: The mixed system of ionic liquid (IL) tetraethyl ammonium tetrafluoroborate [TEA(BF 4 )] and numerous ethylene oxide based non-ionic surfactants in aqueous media were studied using surface tension, viscosity and dynamic light scattering (DLS) measurements. Various surface properties like critical micelle concentration (cmc), maximum surface excess concentration (Γ max ), minimum surface area per surfactant molecule (A min ), surface tension at the cmc (γ cmc ), adsorption efficiency (pC 20 ), and effectiveness of surface tension reduction (π cmc ) as well as thermodynamic parameters of micellization have been determined. DLS and viscosity measurements revealed that the micellar growth was attributed to the bridged solvophilicity of the POE chain in surfactants at elevated temperatures. In most of the cases, the progression ensues from exothermic to endothermic with increase in temperature of the mixed system. Thermodynamic parameter indicates that the micelle formation process is enthalpy driven at low temperature and entropy driven at higher temperature

  5. In vitro surfactant structure-toxicity relationships: implications for surfactant use in sexually transmitted infection prophylaxis and contraception.

    Directory of Open Access Journals (Sweden)

    Ângela S Inácio

    Full Text Available BACKGROUND: The need for woman-controlled, cheap, safe, effective, easy-to-use and easy-to-store topical applications for prophylaxis against sexually transmitted infections (STIs makes surfactant-containing formulations an interesting option that requires a more fundamental knowledge concerning surfactant toxicology and structure-activity relationships. METHODOLOGY/PRINCIPAL FINDINGS: We report in vitro effects of surfactant concentration, exposure time and structure on the viability of mammalian cell types typically encountered in the vagina, namely, fully polarized and confluent epithelial cells, confluent but non-polarized epithelial-like cells, dendritic cells, and human sperm. Representatives of the different families of commercially available surfactants--nonionic (Triton X-100 and monolaurin, zwitterionic (DDPS, anionic (SDS, and cationic (C(nTAB (n = 10 to 16, C(12PB, and C(12BZK--were examined. Triton X-100, monolaurin, DDPS and SDS were toxic to all cell types at concentrations around their critical micelle concentration (CMC suggesting a non-selective mode of action involving cell membrane destabilization and/or destruction. All cationic surfactants were toxic at concentrations far below their CMC and showed significant differences in their toxicity toward polarized as compared with non-polarized cells. Their toxicity was also dependent on the chemical nature of the polar head group. Our results suggest an intracellular locus of action for cationic surfactants and show that their structure-activity relationships could be profitably exploited for STI prophylaxis in vaginal gel formulations. The therapeutic indices comparing polarized epithelial cell toxicity to sperm toxicity for all surfactants examined, except C(12PB and C(12BZK, does not justify their use as contraceptive agents. C(12PB and C(12BZK are shown to have a narrow therapeutic index recommending caution in their use in contraceptive formulations. CONCLUSIONS

  6. Mineral-Surfactant Interactions for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery

    Energy Technology Data Exchange (ETDEWEB)

    P. Somasundaran

    2008-09-20

    /conformation of the adsorbed layers), as well as precipitation/abstraction characteristics. (3) Investigation of the role of dissolved species, especially multivalent ions, on interactions between reservoir minerals and surfactants and/or polymers leading to surfactant precipitation or activated adsorption. (4) Solution behavior tests--surface tension, interaction, ultra filtration, and other tests. (5) Surfactant-mineral interactions relative to adsorption, wettability, and electrophoresis. (6) Work on the effects of multivalent ions, pH, temperature, salinity, and mixing ratio on the adsorption. Developments of adsorption models to explain interactions between surfactants/polymers/minerals. (7) General guidelines for the use of certain surfactants, polymers and their mixtures in micelle flooding processes.

  7. Removal of cationic surfactant (CTAB from aqueous solution on to activated carbon obtained from corncob.

    Directory of Open Access Journals (Sweden)

    S. M. Yakout

    2009-05-01

    Full Text Available Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before water is released to the environment or delivered for public use. Using powdered activated carbon (PAC as adsorbent may be an effective technique to remove surfactants. In this study, the removal of surfactants by PAC was investigated and the influencesof the operating parameters on the effectiveness on adsorption rate were studied. Cationic surfactant, Cetyl trimethyl ammonium bromide (CTAB was selected for the experiments. A series of batch experiments were performed to determine the sorption isotherms of surfactants to PAC. The results showed that carbon structure affect mainly on the surfactant adsorption. Surfactant equilibrium data fitted very well to the binary langmuir model. The pseudo first-,second- order and intraparticle diffusion kinetic models were applied. Both, the external mass transfer and intraparticle diffusion mechanisms involve in CTAB sorption.

  8. Polysaccharide-Based Micelles for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Nan Zhang

    2013-05-01

    Full Text Available Delivery of hydrophobic molecules and proteins has been an issue due to poor bioavailability following administration. Thus, micelle carrier systems are being investigated to improve drug solubility and stability. Due to problems with toxicity and immunogenicity, natural polysaccharides are being explored as substitutes for synthetic polymers in the development of new micelle systems. By grafting hydrophobic moieties to the polysaccharide backbone, self-assembled micelles can be readily formed in aqueous solution. Many polysaccharides also possess inherent bioactivity that can facilitate mucoadhesion, enhanced targeting of specific tissues, and a reduction in the inflammatory response. Furthermore, the hydrophilic nature of some polysaccharides can be exploited to enhance circulatory stability. This review will highlight the advantages of polysaccharide use in the development of drug delivery systems and will provide an overview of the polysaccharide-based micelles that have been developed to date.

  9. A Spectroscopic and Electrochemical Investigation of Interactions of Anticancer Uracil Derivatives with Cationic and Anionic Surfactants

    International Nuclear Information System (INIS)

    Zafar, F.; Shah, A.; Ahmad, Z.; Siddiq, M.; Ali, S.; Asad Muhammad Khan, A. M.; Rana, U. A.

    2015-01-01

    Interactions of 5-fluorouracil (5-FU), a commercially available anti-cancer drug and two other possibly anti-cancer actives, 2-thiouracil (2-TU) and 2,4-dithiouracil (DTU), with anionic sodium dodecyl sulphate (SDS) and cationic cetlytrimethyl ammonium bromide (CTAB) surfactants were studied using cyclic voltammetry and UV-Visible spectroscopic techniques. The results from both techniques asserted the formation of complex between the drugs and surfactants. In the pre-micellar concentrations, the binding was mainly due to the interactions between the surfactants monomers (electrostatic) and the drug molecules, while in the post-micellar region, drug was encapsulated within the micelle due to electrostatic as well as hydrophobic interactions. The UV-Visible spectroscopic data of the interaction between 5-fluorouracil and the surfactants exhibited an isobestic point which indicated the presence of equilibrium species in bulk and the micellar phase. Binding constant, partition coefficient between bulk and miceller phase, and the number of drug molecules incorporated per micelle were calculated. (author)

  10. Electrostatic self-assembly in polyelectrolyte-neutral block copolymers and oppositely charged surfactant solutions

    International Nuclear Information System (INIS)

    Berret, J.-F.Jean-Francois; Oberdisse, Julian

    2004-01-01

    We report on small-angle neutron scattering (SANS) of colloidal complexes resulting from the electrostatic self-assembly of polyelectrolyte-neutral copolymers and oppositely charged surfactants. The polymers are double hydrophilic block copolymers of low molecular weight (between 5000 and 50 000 g/mol). One block is a polyelectrolyte chain, which can be either positively or negatively charged, whereas the second block is neutral and in good solvent conditions. In aqueous solutions, surfactants with an opposite charge to that of the polyelectrolyte interact strongly with these copolymers. The two species associate into stable 100 nm-colloidal complexes which exhibit a core-shell microstructure. For different polymer/surfactant couples, we have shown that the core is constituted from densely packed surfactant micelles connected by the polyelectrolyte chains. The outer part of the complex is a corona formed by the neutral soluble chains. Using a model of aggregation based on a Monte-Carlo algorithm, we have simulated the internal structure of the aggregates. The model assumes spherical cages containing one to several hundreds of micelles in a closely packed state. The agreement between the model and the data is remarkable

  11. Pluronic®-bile salt mixed micelles.

    Science.gov (United States)

    Patel, Vijay; Ray, Debes; Bahadur, Anita; Ma, Junhe; Aswal, V K; Bahadur, Pratap

    2018-06-01

    The present study was aimed to examine the interaction of two bile salts viz. sodium cholate (NaC) and sodium deoxycholate (NaDC) with three ethylene polyoxide-polypropylene polyoxide (PEO-PPO-PEO) triblock copolymers with similar PPO but varying PEO micelles with a focus on the effect of pH on mixed micelles. Mixed micelles of moderately hydrophobic Pluronic ® P123 were examined in the presence of two bile salts and compared with those from very hydrophobic L121 and very hydrophilic F127. Both the bile salts increase the cloud point (CP) of copolymer solution and decreased apparent micelle hydrodynamic diameter (D h ). SANS study revealed that P123 forms small spherical micelles showing a decrease in size on progressive addition of bile salts. The negatively charged mixed micelles contained fewer P123 molecules but progressively rich in bile salt. NaDC being more hydrophobic displays more pronounced effect than NaC. Interestingly, NaC shows micellar growth in acidic media which has been attributed to the formation of bile acids by protonation of carboxylate ion and subsequent solubilization. In contrast, NaDC showed phase separation at higher concentration. Nuclear Overhauser effect spectroscopy (NOESY) experiments provided information on interaction and location of bile salts in micelles. Results are discussed in terms of hydrophobicity of bile salts and Pluronics ® and the site of bile salt in polymer micelles. Proposed molecular interactions are useful to understand more about bile salts which play important role in physiological processes. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Micelles As Delivery System for Cancer Treatment.

    Science.gov (United States)

    Keskin, Dilek; Tezcaner, Aysen

    2017-01-01

    Micelles are nanoparticles formed by the self-assembly of amphiphilic block copolymers in certain solvents above concentrations called critical micelle concentration (CMC). Micelles are used in different fields like food, cosmetics, medicine, etc. These nanosized delivery systems are under spotlight in the recent years with new achievements in terms of their in vivo stability, ability to protect entrapped drug, release kinetics, ease of cellular penetration and thereby increased therapeutic efficacy. Drug loaded micelles can be prepared by dialysis, oil-in-water method, solid dispersion, freezing, spray drying, etc. The aim of this review is to give an overview of the research on micelles (in vitro, in vivo and clinical) as delivery system for cancer treatment. Passive targeting is one route for accumulation of nanosized micellar drug formulations. Many research groups from both academia and industry focus on developing new strategies for improving the therapeutic efficacy of micellar systems (active targeting to the tumor site, designing multidrug delivery systems for overcoming multidrug resistance or micelles formed by prodrug conjugates, etc). There is only one micellar drug formulation in South Korea that has reached clinical practice. However, there are many untargeted anticancer drug loaded micellar formulations in clinical trials, which have potential for use in clinics. Many more products are expected to be on the market in the near future. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  13. Photolithography and Fluorescence Correlation Spectroscopy used to examine the rates of exchange in reverse micelle systems

    Science.gov (United States)

    Norris, Zach; Mawson, Cara; Johnson, Kyron; Kessler, Sarah; Rebecca, Anne; Wolf, Nathan; Lim, Michael; Nucci, Nathaniel

    Reverse micelles are molecular complexes that encapsulate a nanoscale pool of water in a surfactant shell dissolved in non-polar solvent. These complexes have a wide range of applications, and in all cases, the degree to which reverse micelles (RM) exchange their contents is relevant for their use. Despite its importance, this aspect of RM behavior is poorly understood. Photolithography is employed here to create micro and nano scale fluidic systems in which mixing rates can be precisely measured using fluorescence correlation spectroscopy (FCS). Micro-channel patterns are etched using reactive ion etching process into a layer of silicon dioxide on crystalline silicon substrates. Solutions containing mixtures of reverse micelles, proteins, and fluorophores are placed into reservoirs in the patterns, while diffusion and exchange between RMs is monitored using a FCS system built from a modified confocal Raman spectrometer. Using this approach, the diffusion and exchange rates for RM systems are measured as a function of the components of the RM mixture. Funding provided by Rowan University.

  14. Lipoamino acid-based micelles as promising delivery vehicles for monomeric amphotericin B.

    Science.gov (United States)

    Serafim, Cláudia; Ferreira, Inês; Rijo, Patrícia; Pinheiro, Lídia; Faustino, Célia; Calado, António; Garcia-Rio, Luis

    2016-01-30

    Lipoamino acid-based micelles have been developed as delivery vehicles for the hydrophobic drug amphotericin B (AmB). The micellar solubilisation of AmB by a gemini lipoamino acid (LAA) derived from cysteine and its equimolar mixtures with the bile salts sodium cholate (NaC) and sodium deoxycholate (NaDC), as well as the aggregation sate of the drug in the micellar systems, was studied under biomimetic conditions (phosphate buffered-saline, pH 7.4) using UV-vis spectroscopy. Pure surfactant systems and equimolar mixtures were characterized by tensiometry and important parameters were determined, such as critical micelle concentration (CMC), surface tension at the CMC (γCMC), maximum surface excess concentration (Γmax), and minimum area occupied per molecule at the water/air interface (Amin). Rheological behaviour from viscosity measurements at different shear rates was also addressed. Solubilisation capacity was quantified in terms of molar solubilisation ratio (χ), micelle-water partition coefficient (KM) and Gibbs energy of solubilisation (ΔGs°). Formulations of AmB in micellar media were compared in terms of drug loading, encapsulation efficiency, aggregation state of AmB and in vitro antifungal activity against Candida albicans. The LAA-containing micellar systems solubilise AmB in its monomeric and less toxic form and exhibit in vitro antifungal activity comparable to that of the commercial formulation Fungizone. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Influence of system size and solvent flow on the distribution of wormlike micelles in a contraction-expansion geometry

    Science.gov (United States)

    Stukan, M. R.; Boek, E. S.; Padding, J. T.; Crawshaw, J. P.

    2008-05-01

    Viscoelastic wormlike micelles are formed by surfactants assembling into elongated cylindrical structures. These structures respond to flow by aligning, breaking and reforming. Their response to the complex flow fields encountered in porous media is particularly rich. Here we use a realistic mesoscopic Brownian Dynamics model to investigate the flow of a viscoelastic surfactant (VES) fluid through individual pores idealized as a step expansion-contraction of size around one micron. In a previous study, we assumed the flow field to be Newtonian. Here we extend the work to include the non-Newtonian flow field previously obtained by experiment. The size of the simulations is also increased so that the pore is much larger than the radius of gyration of the micelles. For the non-Newtonian flow field at the higher flow rates in relatively large pores, the density of the micelles becomes markedly non-uniform. In this case, we find that the density in the large, slowly moving entry corner regions is substantially increased.

  16. Reverse micelles in organic solvents: a medium for the biotechnological use of extreme halophilic enzymes at low salt concentration

    Directory of Open Access Journals (Sweden)

    Frutos C. Marhuenda-Egea

    2002-01-01

    Full Text Available Alkaline p-nitrophenylphosphate phosphatase (pNPPase from the halophilic archaeobacterium Halobacterium salinarum (previously halobium was solubilized at low salt concentration in reverse micelles of hexadecyltrimethylammoniumbromide in cyclohexane with 1-butanol as cosurfactant. The enzyme maintained its catalytic properties under these conditions. The thermodynamic “solvation–stabilization hypothesis” has been used to explain the bell-shaped dependence of pNPPase activity on the water content of reverse micelles, in terms of protein–solvent interactions. According to this model, the stability of the folded protein depends on a network of hydrated ions associated with acidic residues at the protein surface. At low salt concentration and low water content (the ratio of water concentration to surfactant concentration; w0, the network of hydrated ions within the reverse micelles may involve the cationic heads of the surfactant. The bell-shaped profile of the relationship between enzyme activity and w0 varied depending on the concentrations of NaCl and Mn2+.

  17. Thermodynamics of self-assembling of mixture of a cationic gemini surfactant and sodium dodecylsulfate in aqueous solution: Calorimetry, conductivity and surface pressure measurements

    International Nuclear Information System (INIS)

    Bai, Guangyue; Wang, Yujie; Ding, Yanhong; Zhuo, Kelei; Wang, Jianji; Bastos, Margarida

    2016-01-01

    Highlights: • ITC provided thermodynamic characterization of self-association of oppositely charged gemini/SDS surfactants. • Phase transitions and corresponding enthalpies were obtained by ITC. • The transitions reflect a change in morphology, supported by Cryo-TEM images. • Conductivity and ITC results show very good agreement. • An asymmetric distribution of surfactants in the aggregates is supported by results. - Abstract: The thermodynamics and phase behavior of mixtures of cationic gemini surfactant decanediyl-α,ω-bis(dodecyldimethylammonium bromide) (12-10-12) and sodium dodecylsulfate (SDS) were studied in the dilute SDS-rich region. The enthalpy of interaction between both surfactant monomers before the critical micelle concentration for the mixture (cmc_m_i_x) was determined by isothermal titration calorimetry (ITC). After the cmc_m_i_x, ITC results exhibited a first process associated with a large endothermic enthalpy change followed by a second one with a very small exothermic enthalpy change. In the same regions, the conductivity curves show an increase in slope after the break, followed by a plateau region, respectively for the two processes. The combined results from the various methodologies used lead us to propose that the first process reflects the formation of non-spherical micelles and the second one the vesicle formation. The area per catanionic complex was obtained through surface pressure measurements, leading to an apparent packing parameter ⩾1. The observed behavior may be rationalized on the basis of the hypothesis that both surfactants distribute asymmetrically in the vesicle bilayers and unevenly in the non-spherical micelle. In order to get structural information Cryo-TEM experiments were performed, which provided images that support this interpretation. From all the information gathered a phase diagram was mapped, including three one-phase regions of spherical micelles, non-spherical micelles and vesicles.

  18. Solubilization and Interaction Studies of Bile Salts with Surfactants and Drugs: a Review.

    Science.gov (United States)

    Malik, Nisar Ahmad

    2016-05-01

    In this review, bile salt, bile salt-surfactant, and bile salt-drug interactions and their solubilization studies are mainly focused. Usefulness of bile salts in digestion, absorption, and excretion of various compounds and their rare properties in ordering the shape and size of the micelles owing to the presence of hydrophobic and hydrophilic faces are taken into consideration while compiling this review. Bile salts as potential bio-surfactants to solubilize drugs of interest are also highlighted. This review will give an insight into the selection of drugs in different applications as their properties get modified by interaction with bile salts, thus influencing their solution behavior which, in turn, modifies the phase-forming behavior, microemulsion, and clouding phenomenon, besides solubilization. Finally, their future perspectives are taken into consideration to assess their possible uses as bio-surfactants without side effects to human beings.

  19. Influence of Valsartan on the thermodynamics of micellization of anionic surfactant Sodium Dodecyl Sulphate

    Directory of Open Access Journals (Sweden)

    Stopková L.

    2016-12-01

    Full Text Available In this manuscript was investigated behaviour of drug valsartan by micellar media of anionic surfactant sodium dodecyl sulphate. As the method was used electrical conductivity for the determination of critical micelle concentration at different temperatures (T = 293.15 - 313.15 K, as well as calculated thermodynamic parameters like standard Gibbs free energy, enthalpy and entropy of micellization. According to contribution of Gibbs free energy is the process of micellization primarily controlled by entropy. Solubilization of valsartan was studied in surfactant system at 298.15 K and physiological conditions pH 7.4 using UV-spectrophotometry at different concentration range (0.001 - 0.07 mol/l of sodium dodecyl sulphate. The solubilization of drug was observed with increasing concentration of surfactant in aqueous solution.

  20. Influence of anionic surfactant on the process of electro-Fenton decolorized methyl orange.

    Science.gov (United States)

    Ren, B X

    2010-01-01

    The electro-Fenton process has been shown to be very successful to remove dyes from water. However, the influence of other constituents in dyeing industry wastewater, such as Sodium Dodecyl Sulfate (SDS) surfactants, has not been investigated. In this study, the effect of SDS surfactant on the kinetics of Methyl Orange degradation undergoing Electro-Fenton process was investigated. Results show that Methyl Orange degradation rate decreased as SDS concentration (below Critical Micelle Concentration, CMC) increased, which was attributed to the consumption of hydroxyl radicals (( )OH) by surfactants. The kinetics modeling indicates the reaction was the first-order reaction to Methyl Orange even SDS existing. The pseudo first-order rate constants decreased as SDS concentration increased.

  1. Separation process for lanthanides based on solvation properties of non ionic surfactants

    International Nuclear Information System (INIS)

    Draye, M.; Favre-Reguillon, A.; Foos, J.; Cote, G.

    2004-01-01

    In the present study, cloud-point extraction is used with a lipophilic chelating agent (8-hydroxyquinoline) to extract and separate lanthanum (III) and gadolinium (III) from an aqueous solution. The methodology used is based on the formation of lanthanide (III) organic complexes that are soluble in a micellar phase of non-ionic surfactant. The lanthanide (III) complexes are then extracted into the surfactant-rich phase at a temperature above the cloud-point temperature. The cloud-point temperature, the structure of the lipophilic part of the nonionic surfactant and the chelating agent - metal molar ratio are identified as factors determining the extraction efficiency and selectivity. With Triton X-114, high selectivity and decontamination factor for Gd(III) is observed indicating that micelle mediated extraction involving cloud-point extraction is promising for the specific separation of actinide ions from nuclear waste solution. (authors)

  2. Recycling of surfactant template in mesoporous MCM-41 synthesis

    Science.gov (United States)

    Lai, J. Y.; Twaiq, F.; Ngu, L. H.

    2017-06-01

    The recycling of surfactant template is investigated through the reuse of the surfactant template in the mesoporous MCM-41 synthesis process. In the synthesis of MCM-41, tetraethylorthosilicate (TEOS) solution in water was utilized as the silica source while hexadecyltrimethylammonium bromide (CTAB) solution in ethyl alcohol was used as a surfactant template. The synthesized gel is formed thoroughly by mixing the two solutions under acid conditions with a pH value of 0.5 for 1 hour and kept for crystallization for 48 hours. The as-synthesized MCM-41 powder is recovered by filtration while the filtrate (mother liquor) was then reused for the second synthesis cycle. The synthesis procedure was repeated till no further solid product was formed. The synthesized gel was not produced in the unifying solution in the fifth cycle of MCM-41 synthesis. The quality of the calcined MCM-41 powder produced in each synthesis cycle was evaluated by calculating the amount of MCM-41 produced and the surface area of the powder product. The result showed that 1.28, 0.37, 1.64, 1.90 and 0.037 g were obtained in the 1st, 2nd, 3rd, 4th and 5th synthesis cycle, respectively. The surface area of the powder produced was found to be 1170, 916, 728, and 508 m2/g for 1st, 2nd, 3rd and 4th respectively. The concentration of the surfactant template has reached value lower than the critical micelle concentration (CMC) and remained constant after the 4th cycle. There was no further formation of gel due to low availability in the interaction between silicate anions and surfactant cations when the amount of TEOS was fixed for every synthesis cycle.

  3. Modulation of the wettability of excipients by surfactant and its impacts on the disintegration and release of tablets.

    Science.gov (United States)

    Yang, Baixue; Xu, Lu; Wang, Qiuxiao; Li, Sanming

    2016-12-01

    To investigate the modulation of the wettability of excipients by different types of surfactants and its impacts on the disintegration of tablets and drug release. The critical micelle concentration (CMC) of surfactants, including sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), dodecyl trimethyl ammonium bromide (DTAB), cetyltrimethyl ammonium bromide (CTAB) and polysorbate (Tween-20 and Tween-80), was obtained using the platinum ring method. Contact angles of surfactant solutions on the excipient compacts and double-distilled water on the mixture of surfactant and the other excipient (magnesium stearate (MgSt) or sodium alginate (SA)) were measured by the sessile drop technique. Besides, surface free energy of excipients was calculated by the Owens method. Finally, the disintegration of tablets and in vitro dissolution testing were performed according to the method described in USP. The wettability of excipients could be enhanced to different extent with low concentration of surfactant solutions and maintained stable basically after CMC. For MgSt (hydrophobic excipient), the shorter the hydrophobic chain (C 12 , including SDS and DTAB), the better the wettability with the addition of surfactant in the formulation, leading to the shorter disintegration time of tablets and higher drug release rate. In contrast, the wettability of SA (hydrophilic excipient) was reduced by adding surfactant, resulting in the longer disintegration time of tablets and lower release rate. The modulation of the wetting of pharmaceutical excipients by surfactant had changed the disintegration time of tablets and drug release rate to a greater extent.

  4. Surfactants from petroleum paraffin wax

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, T.M.; Hussein, M.H.; El Sayed, A.S.

    Paraffin wax from Egyptian petroleum was purified and then oxidized to fatty acids which were esterified to form their methyl esters, fractionated and then hydrolysed. The obtained fatty acids were converted into the corresponding primary amines which were converted with ethylene oxide to form nonionic surfactants. The prepared primary amines were also converted into tertiary amines and then converted into cationic surfactants through condensation with benzyl chloride or 1-chloromethylnaphthalene. Also, amine oxide surfactants were prepared by oxidation of the tertiary amines with hydrogen peroxide. The surface active properties of all the prepared surfactants were determined, and the effect of their chemical structure on the surfactant properties are discussed in this paper.

  5. Microbial surfactant activities from a petrochemical landfarm in a humid tropical region of Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Maciel, B.M.; Dias, J.C.T.; Santos, A.C.F.; Argolo-Filho, R.C.; Fontana, R.; Loguercio, L.L.; Rezende, R.P. [Univ. Estadual de Santa Cruz, Santa Cruz (Brazil). Dept. de Ciencias Biologicas

    2007-08-15

    Studies have suggested that biosurfactants can enhance the biodegradation of almost insoluble organics by increasing cell uptake availability. In this study, micro-organisms were isolated from a soil sample from a Brazilian petrochemical waste landfarm and grown in petroleum as a carbon source in order to assess their surfactant potential. Isolated colonies were inoculated into tubes, and a drop-collapse method was used to select micro-organisms with surfactant activity. Surfactant activity of the isolates was assessed when the activity was detected for the first time in each culture. The supernatant of each micro-organism was then diluted. The surfactant activity of each dilution was then observed via micelles formation. DNA was then extracted from the samples. A total of 60 microbial strains were selected. Results showed that a variety of petroleum-grown micro-organisms obtained from the landfarm soil showed surfactant activity. Results showed that the micro-organisms were able to use petroleum as a sole carbon source. The production of surfactant compounds occurred during the declining stages of microbial culture curves, which suggested that the nutritional stress achieved on the fourth day of the culture induced the synthesis and secretion of biosurfactants by the isolates. It was concluded that micro-organisms derived from soils polluted with hydrocarbons can be used in bioremediation processes. 21 refs., 1 tab., 3 figs.

  6. Surfactant-induced mobilisation of trace metals from estuarine sediment: Implications for contaminant bioaccessibility and remediation

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anu [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Turner, Andrew [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)], E-mail: aturner@plymouth.ac.uk

    2009-02-15

    The mobilisation of metals (Al, Fe, Cd, Cu, Mn, Ni, Pb, Sn, Zn) from contaminated estuarine sediment has been examined using commercially available surfactants. Metal release by the anionic surfactant, sodium dodecyl sulphate (SDS), increased with increasing amphiphile concentration up to and above its critical micelle concentration (CMC). Metal mobilisation by the bile acid salt, sodium taurocholate, and the nonionic surfactant, Triton X-100, however, did not vary with amphiphile concentration. SDS was the most efficient surfactant in mobilising metals from the sample, and Cd, Cu and Ni were released to the greatest extents (12-18% of total metal at [SDS] > CMC). Metal mobilisation appeared to proceed via complexation with anionic amphiphiles and denudation of hydrophobic host phases. Surfactants may play an important role in the solubilisation of metals in the digestive environment of deposit-feeding animals and, potentially, in the remediation of metal-contaminated soil and sediment. - Significant quantities of metals are mobilised from estuarine sediment by commercially available surfactants.

  7. Synthesis, surface properties and antimicrobial activity of some germanium nonionic surfactants.

    Science.gov (United States)

    Zaki, Mohamed F; Tawfik, Salah M

    2014-01-01

    Esterification reaction between different fatty acid namely; lauric, stearic, oleic and linoleic acids and polyethylene glycol-400 were performed. The produced polyethylene glycol ester were reacted with p-amine benzoic acid followed by condensation reaction with germanium dioxide in presence of sodium carbonate to form desired germinate surfactants. The chemical structures of the synthesized surfactants were determined using different spectra tools. The surface parameter including: the critical micelle concentration (CMC), effectiveness (π(cmc)), efficiency (Pc20), maximum surface excess (Γ(max)) and minimum surface area (A(min)), were calculated from the surface tension measurements. The synthesized surfactants showed higher surface activity. The thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the synthesized nonionic surfactants showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. The synthesized surfactants were tested against different strain of bacteria using inhibition zone diameters. The synthesized surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The promising inhibition efficiency of these compounds against the sulfate reducing bacteria facilitates them to be applicable as new categories of sulfate reducing bacteria biocides.

  8. Dilational viscoelastic properties of fluid interfaces - III mixed surfactant systems

    Energy Technology Data Exchange (ETDEWEB)

    Djabbarah, N.F.; Wasan, D.T.

    1982-01-01

    The surface viscosity and elasticity of solutions of mixed surfactants were determined using the longitudinal wave technique combined with tracer particle measurements. The recent analysis of Maru et al., which was restricted to insoluble monolayers and to monolayers adsorbed from a single surfactant solution, has now been extended to multicomponent solutions. This analysis can be used not only to estimate the ''net'' viscoelastic properties at gas-liquid interfaces but also to estimate the composition as well as the intrinsic viscoelastic properties. Furthermore, when accompanied by separate measurements of shear viscoelastic properties, the above analysis can be used for the determination of dilational viscosity and elasticity. Surface viscoelasticity measurements were conducted on aqueous solutions of sodium lauryl sulfate and sodium lauryl sulfate-lauryl alcohol. Net surface viscosity and elasticity of sodium lauryl sulfate solutions increased with bulk concentration and reached a maximum at a concentration in the neighborhood of the critical micelle concentration. The presence of small amount of lauryl alcohol caused almost an order of magnitude increase in intrinsic surface viscosity and a similar increase in compositional surface elasticity. A comparison between the values of intrinsic surface viscosity and those of surface shear viscosity indicated that surface dilational viscosity exceeds surface shear viscosity by at least two orders of magnitude. These appear to be the first set of data presented hitherto for the surface dilational properties in addition to surface shear properties for the same mixed surfactant systems.

  9. Surfactant mediated slurry formulations for Ge CMP applications

    KAUST Repository

    Basim, G. Bahar

    2013-01-01

    In this study, slurry formulations in the presence of self-assembled surfactant structures were investigated for Ge/SiO2 CMP applications in the absence and presence of oxidizers. Both anionic (sodium dodecyl sulfate-SDS) and cationic (cetyl trimethyl ammonium bromide-C12TAB) micelles were used in the slurry formulations as a function of pH and oxidizer concentration. CMP performances of Ge and SiO2 wafers were evaluated in terms of material removal rates, selectivity and surface quality. The material removal rate responses were also assessed through AFM wear rate tests to obtain a faster response for preliminary analyses. The surfactant adsorption characteristics were studied through surface wettability responses of the Ge and SiO2 wafers through contact angle measurements. It was observed that the self-assembled surfactant structures can help obtain selectivity on the silica/germanium system at low concentrations of the oxidizer in the slurry. © 2013 Materials Research Society.

  10. Polymeric micelles for ocular drug delivery: From structural frameworks to recent preclinical studies.

    Science.gov (United States)

    Mandal, Abhirup; Bisht, Rohit; Rupenthal, Ilva D; Mitra, Ashim K

    2017-02-28

    Effective intraocular drug delivery poses a major challenge due to the presence of various elimination mechanisms and physiological barriers that result in low ocular bioavailability after topical application. Over the past decades, polymeric micelles have emerged as one of the most promising drug delivery platforms for the management of ocular diseases affecting the anterior (dry eye syndrome) and posterior (age-related macular degeneration, diabetic retinopathy and glaucoma) segments of the eye. Promising preclinical efficacy results from both in-vitro and in-vivo animal studies have led to their steady progression through clinical trials. The mucoadhesive nature of these polymeric micelles results in enhanced contact with the ocular surface while their small size allows better tissue penetration. Most importantly, being highly water soluble, these polymeric micelles generate clear aqueous solutions which allows easy application in the form of eye drops without any vision interference. Enhanced stability, larger cargo capacity, non-toxicity, ease of surface modification and controlled drug release are additional advantages with polymeric micelles. Finally, simple and cost effective fabrication techniques render their industrial acceptance relatively high. This review summarizes structural frameworks, methods of preparation, physicochemical properties, patented inventions and recent advances of these micelles as effective carriers for ocular drug delivery highlighting their performance in preclinical studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Entropic effects, shape, and size of mixed micelles formed by copolymers with complex architectures

    Science.gov (United States)

    Kalogirou, Andreas; Gergidis, Leonidas N.; Moultos, Othonas; Vlahos, Costas

    2015-11-01

    The entropic effects in the comicellization behavior of amphiphilic A B copolymers differing in the chain size of solvophilic A parts were studied by means of molecular dynamics simulations. In particular, mixtures of miktoarm star copolymers differing in the molecular weight of solvophilic arms were investigated. We found that the critical micelle concentration values show a positive deviation from the analytical predictions of the molecular theory of comicellization for chemically identical copolymers. This can be attributed to the effective interactions between copolymers originated from the arm size asymmetry. The effective interactions induce a very small decrease in the aggregation number of preferential micelles triggering the nonrandom mixing between the solvophilic moieties in the corona. Additionally, in order to specify how the chain architecture affects the size distribution and the shape of mixed micelles we studied star-shaped, H-shaped, and homo-linked-rings-linear mixtures. In the first case the individual constituents form micelles with preferential and wide aggregation numbers and in the latter case the individual constituents form wormlike and spherical micelles.

  12. Antiproliferative activity of tea catechins associated with casein micelles, using HT29 colon cancer cells.

    Science.gov (United States)

    Haratifar, S; Meckling, K A; Corredig, M

    2014-02-01

    Numerous studies have shown that green tea polyphenols display anticancer activities in many organ sites by using different experimental models in rodents and in cultured cell lines in vitro. The present study tested the ability of casein micelles to deliver biologically active concentrations of polyphenols to HT-29 colon cancer cells. Epigallocatechin gallate (EGCG), the major catechin found in green tea, was used as the model molecule, as it has been shown to have antiproliferative activity on colon cancer cells. In the present work, we hypothesized that due to the binding of caseins with EGCG, casein micelles may be an ideal platform for the delivery of this bioactive molecule and that the binding would not affect the bioaccessibility of EGCG. The cytotoxicity and proliferation behavior of HT-29 colon cancer cells when exposed to free EGCG was compared with that of nanoencapsulated EGCG in casein micelles of skim milk. Epigallocatechin gallate-casein complexes were able to decrease the proliferation of HT-29 cancer cells, demonstrating that bioavailability may not be reduced by the nanoencapsulation. As casein micelles may act as protective carriers for EGCG in foods, it was concluded that nanoencapsulation of tea catechins in casein micelles may not diminish their antiproliferative activity on colon cancer cells compared with free tea catechins. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  13. Novel designed polyoxyethylene nonionic surfactant with improved safety and efficiency for anticancer drug delivery

    Directory of Open Access Journals (Sweden)

    Li C

    2014-04-01

    Full Text Available Chang Li,1 Chunmeng Sun,1 Shasha Li,1 Peng Han,2 Huimin Sun,3 Ammar Ouahab,1 Yan Shen,1 Yourui Xu,1 Yerong Xiong,1 Jiasheng Tu11State Key Laboratory of Natural Medicines, Department of Pharmaceutics, China Pharmaceutical University, Nanjing, 2Chinese Pharmacopoeia Commission, Beijing, 3National Institute for Food and Drug Control, Beijing, People's Republic of ChinaAbstract: In order to limit the adverse reactions caused by polysorbate 80 in Taxotere®, a widely used formulation of docetaxel, a safe and effective nanocarrier for this drug has been developed based on micelles formed by a new class of well-defined polyoxyethylene sorbitol oleate (PSO with sorbitol as the matrix in aqueous solution. The physicochemical properties of the amphiphilic surfactant and the resulting micelles can be easily fine-tuned by the homogeneous sorbitol matrix and pure oleic acid. Composition, critical micelle concentration, and entrapment efficiency were investigated by ultraviolet visible spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, fluorospectrophotometry, and high-performance liquid chromatography. In vitro and in vivo evaluation revealed that PSO had exceptionally low hemolysis and histamine release rates compared with commercial polysorbate 80. Moreover, the tumor targeting delivery of PSO was investigated by in vivo imaging in S180 tumor-bearing mice. The results suggest that this novel delivery system, PSO, provides an acceptable alternative to polysorbate 80 for delivery of docetaxel. Further, due to the hypoallergenic nature of PSO, the mechanism of pseudoallergy caused by the polyoxyethylene nonionic surfactant was investigated. Based on in vitro cell analysis, it was assumed that the initial contact of polyoxyethylene nonionic surfactant with mast cells provoked pseudoallergy via polyamine receptor-mediated endocytosis.Keywords: polyoxyethylene nonionic surfactant, sorbitol, isosorbide, pseudoallergy

  14. Evolvement of soft templates in surfactant/cosurfactant system for shape control of ZnSe nanocrystals

    International Nuclear Information System (INIS)

    Hou Bo; Liu Yongjun; Li Yanjuan; Yuan Bo; Jia Mingfen; Jiang Fengzhi

    2012-01-01

    Highlights: ► Soft templates were found in the shape control synthesis of ZnSe nanocrystals. ► Micelle formation model in the soft templates system was proposed and proved. ► Different shapes of ZnSe nanocrystals were prepared and explained by proposed model. - Abstract: The evolution of soft templates in the synthesis of ZnSe nanocrystals realized through a surfactant/cosurfactant system was investigated and a micelle formation process model was proposed. Through freeze-fracture electron microscopy, it was proven that template micelles were formed in the zinc precursors. Furthermore, it was found that a long stirring period was essential for achieving the lowest energy state of the soft templates which were used for synthesizing monodisperse ZnSe quantum dots.

  15. Evolvement of soft templates in surfactant/cosurfactant system for shape control of ZnSe nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hou Bo [Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming 650091 (China); Liu Yongjun [Advanced Analysis and Measurement Center, Yunnan University, Kunming 650091 (China); Li Yanjuan [Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming 650091 (China); Yuan Bo [Advanced Analysis and Measurement Center, Yunnan University, Kunming 650091 (China); Jia Mingfen [Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming 650091 (China); Jiang Fengzhi, E-mail: fengzhij@ynu.edu.cn [Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming 650091 (China); Advanced Analysis and Measurement Center, Yunnan University, Kunming 650091 (China)

    2012-03-25

    Highlights: Black-Right-Pointing-Pointer Soft templates were found in the shape control synthesis of ZnSe nanocrystals. Black-Right-Pointing-Pointer Micelle formation model in the soft templates system was proposed and proved. Black-Right-Pointing-Pointer Different shapes of ZnSe nanocrystals were prepared and explained by proposed model. - Abstract: The evolution of soft templates in the synthesis of ZnSe nanocrystals realized through a surfactant/cosurfactant system was investigated and a micelle formation process model was proposed. Through freeze-fracture electron microscopy, it was proven that template micelles were formed in the zinc precursors. Furthermore, it was found that a long stirring period was essential for achieving the lowest energy state of the soft templates which were used for synthesizing monodisperse ZnSe quantum dots.

  16. Micellization behaviour and thermodynamic parameters of 12-2-12 gemini surfactant in (water + organic solvent) mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Batigoec, Cigdem [Department of Chemistry, Faculty of Sciences, Trakya University, 22030 Edirne (Turkey); Akbas, Halide, E-mail: hakbas34@yahoo.com [Department of Chemistry, Faculty of Sciences, Trakya University, 22030 Edirne (Turkey); Boz, Mesut [Department of Chemistry, Faculty of Sciences, Trakya University, 22030 Edirne (Turkey)

    2011-09-15

    Highlights: > The cmc and {alpha} values of surfactant increased with increasing solvent content and temperature. > The values of ({Delta}G{sub m}{sup 0}) are negative in all cases for the micelle formation becomes less favourable. > The values of negative enthalpy indicate importance of the London dispersion forces for the micellization. > The positive entropy is due to a contribution supplied from the solvent. - Abstract: The effect of organic solvents on micellization behaviour and thermodynamic parameters of a cationic gemini (dimeric) surfactant, C{sub 12}H{sub 25}(CH{sub 3}){sub 2}N{sup +}-(CH{sub 2}){sub 2}-N{sup +}(CH{sub 3}){sub 2}C{sub 12}H{sub 25}.2Br{sup -}, (12-2-12) was studied in aqueous solutions over the range of T = (293.15 to 323.15) K using the conductometric technique. Ethylene glycol (EG), dimethylsulfoxide (DMSO) and 1,4-dioxan (DO) were used as organic solvents with three different contents. The critical micelle concentration (cmc) and the degree of counter ion dissociation ({alpha}) of micelles in the water and in the (water + organic solvent) mixtures including 10%, 20%, and 30% solvent contents were determined. The standard Gibbs free energy ({Delta}G{sub m}{sup 0}), enthalpy ({Delta}H{sub m}{sup 0}) and entropy ({Delta}S{sub m}{sup 0}) of micellization were estimated from the temperature dependence of the cmc values. It was observed that the critical micelle concentration of the gemini surfactant and the degree of counter ion dissociation of the micelle increased as the volume percentage of organic solvent, and temperature increased. The standard Gibbs free energy of micellization was found to be less negative with the increase in the organic solvent content and temperature.

  17. Pressure effects on enzyme reactions in mainly organic media: alpha-chymotrypsin in reversed micelles of Aerosol OT in octane.

    Science.gov (United States)

    Mozhaev, V V; Bec, N; Balny, C

    1994-08-01

    Biocatalytic transformations in reversed micelles formed by anionic surfactant Aerosol OT in octane have been studied at high pressures by an example of alpha-chymotrypsin-catalyzed hydrolysis of N-carbobenzoxy-L-tyrosine p-nitrophenyl ester and N-succinyl-L-phenylalanine p-nitroanilide. For the first time it has been found that the enzyme retains high activity in these water-in-oil microemulsions up to a pressure of 2 kbar. The value of the activation volume (delta V*) for the enzyme reactions shows a dependence on the water content in the system. When the size of the micellar aqueous inner cavity (as evaluated at 1 atm) approaches the molecular size of alpha-chymotrypsin, delta V* becomes significantly different from the value in aqueous solution and in the micelles with a larger size. Possibilities of regulating the enzyme activity by pressure in systems with a low content of water are discussed.

  18. Natural organic matter removal by adsorption onto magnetic permanently confined micelle arrays

    International Nuclear Information System (INIS)

    Wang, Hongtao; Keller, Arturo A.; Clark, Kristin K.

    2011-01-01

    Highlights: → New nanostructured material for removing pollutants from water. → Confined surfactant micelle array allows for reuse of surfactant and reduces loss. → Magnetic core allows easy removal from solution with lower separation costs. → High removal efficiency of natural organic matter. → Low energy use for regeneration of adsorbent. - Abstract: To remove natural organic matter (NOM) from water, magnetic permanently confined micelle arrays (Mag-PCMAs) were synthesized by coating the surface of Fe 3 O 4 particles with a silica/surfactant mesostructured hybrid layer. An environmental scanning electron microscope (ESEM) was used to characterize the particle size and surface morphology of the Mag-PCMAs. The zeta potential was used to assess the surface charge. Batch experiments were performed to investigate the adsorption of NOM by Mag-PCMAs. It was determined that NOM removal efficiency by Mag-PCMAs could be as high as 80% at a wide range of initial pH values (∼6.0-10.0). The adsorption isotherm was fitted well by a Langmuir model. Although Fe 3 O 4 had a high positive charge and Mag-PCMAs a small negative charge, Mag-PCMAs had a higher removal efficiency of NOM than uncoated Fe 3 O 4 particles (which are also magnetic), which indicated that the adsorption of NOM onto Mag-PCMAs was not dominated by electrostatic interactions. Possible mechanisms of the adsorption of NOM onto Mag-PCMAs were hydrophobic interactions and hydrogen bonding. It was feasible to reuse Mag-PCMAs after regeneration. These results indicate that Mag-PCMAs can be very attractive for the removal of NOM from aqueous matrices.

  19. Structural properties of self-assembled polymeric micelles

    DEFF Research Database (Denmark)

    Mortensen, K.

    1998-01-01

    At present, the thermodynamic understanding of complex copolymer systems is undergoing important developments. Block copolymers aggregate in selective solvents into micelles of various form and size depending on molecular architecture and interaction parameters. The micelles constitute the basis ...

  20. In situ electron-beam polymerization stabilized quantum dot micelles.

    Science.gov (United States)

    Travert-Branger, Nathalie; Dubois, Fabien; Renault, Jean-Philippe; Pin, Serge; Mahler, Benoit; Gravel, Edmond; Dubertret, Benoit; Doris, Eric

    2011-04-19

    A polymerizable amphiphile polymer containing PEG was synthesized and used to encapsulate quantum dots in micelles. The quantum dot micelles were then polymerized using a "clean" electron beam process that did not require any post-irradiation purification. Fluorescence spectroscopy revealed that the polymerized micelles provided an organic coating that preserved the quantum dot fluorescence better than nonpolymerized micelles, even under harsh conditions. © 2011 American Chemical Society

  1. Biocatalytic synthesis of polymeric nanowires by micellar templates of ionic surfactants

    International Nuclear Information System (INIS)

    Nazari, K.; Adhami, F.; Najjar-Safari, A.; Salmani, S.; Mahmoudi, A.

    2011-01-01

    Highlights: → Soft-template production of polyguaiacol nanowire was done by peroxidase enzyme. → Main advantage of this simple method is producing soluble encapsulated nanowires. → Nanowire can be easily precipitated and separated by dilution with distilled water. → Size tuned templates of sodium decyl sulfate (d = 2.7 nm) gave nanowires with d = 2-4 nm. → Dried surfactant-coated wires recover freshly on specified and desired applications. -- Abstract: Micelle-templated polyguaiacol nanowires were successfully prepared via polymerization oxidation of guaiacol (o-methoxy phenol) by peroxidase enzyme in the presence of hydrogen peroxide at mild reaction conditions. The dimensions of the prepared nanowires were controlled by tuning the size and shape of the micelle structure via changing and controlling the type, chain length and molar concentrations of the ionic surfactant. The progress of the reaction and estimation of the size of soft micellar templates were followed by UV-Vis spectroscopy and dynamic light scattering (DLS). The resulting micelle encapsulated or purified polyguaiacol nanowires were characterized using transmission electron microscopy (TEM).

  2. Biocatalytic synthesis of polymeric nanowires by micellar templates of ionic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Nazari, K., E-mail: nazarikh@ripi.ir [Research Institute of Petroleum Industry, NIOC, P.O. Box 14665-137, Tehran (Iran, Islamic Republic of); Chemistry Dept., Shahr Rey Islamic Azad University, P.O. Box 18735-334, Tehran (Iran, Islamic Republic of); Adhami, F.; Najjar-Safari, A.; Salmani, S. [Chemistry Dept., Shahr Rey Islamic Azad University, P.O. Box 18735-334, Tehran (Iran, Islamic Republic of); Mahmoudi, A. [Chemistry Dept., Karaj Islamic Azad University, Karaj (Iran, Islamic Republic of)

    2011-07-15

    Highlights: {yields} Soft-template production of polyguaiacol nanowire was done by peroxidase enzyme. {yields} Main advantage of this simple method is producing soluble encapsulated nanowires. {yields} Nanowire can be easily precipitated and separated by dilution with distilled water. {yields} Size tuned templates of sodium decyl sulfate (d = 2.7 nm) gave nanowires with d = 2-4 nm. {yields} Dried surfactant-coated wires recover freshly on specified and desired applications. -- Abstract: Micelle-templated polyguaiacol nanowires were successfully prepared via polymerization oxidation of guaiacol (o-methoxy phenol) by peroxidase enzyme in the presence of hydrogen peroxide at mild reaction conditions. The dimensions of the prepared nanowires were controlled by tuning the size and shape of the micelle structure via changing and controlling the type, chain length and molar concentrations of the ionic surfactant. The progress of the reaction and estimation of the size of soft micellar templates were followed by UV-Vis spectroscopy and dynamic light scattering (DLS). The resulting micelle encapsulated or purified polyguaiacol nanowires were characterized using transmission electron microscopy (TEM).

  3. Surface and micellar properties of Chloroquine Diphosphate and its interactions with surfactants and Human Serum Albumin

    International Nuclear Information System (INIS)

    Usman, Muhammad; Siddiq, Mohammad

    2013-01-01

    Highlights: ► Free energy of adsorption is more negative than free energy of micellization. ► Shifts in UV/Visible spectra in presence of SDS indicated interaction of CLQ with SDS. ► The decrease in fluorescence intensity of HSA by CLQ shows its binding with HSA. -- Abstract: This manuscript addresses the physicochemical behavior of an antimalarial drug Chloroquine Diphosphate (CLQ) as well as its interaction with anionic surfactants and Human Serum Albumin (HSA). Surface tension and specific conductivity were employed to detect the critical micelle concentration (CMC) and thus its surface and thermodynamic parameters were calculated. Solubilization of this drug within micelles of anionic surfactant sodium dodecyl sulfate (SDS) has also been studied. UV/Visible spectroscopy was used to calculate partition coefficient (K x ), free energy of partition and number of drug molecules per micelle. The complexation of drug with HSA at physiological conditions (pH 7.4) has also been analyzed by using UV/Visible and fluorescence spectroscopy. The values of drug-protein binding constant, number of binding sites and free energy of binding were calculated

  4. Dust as a surfactant

    International Nuclear Information System (INIS)

    Ignatov, A M; Schram, P P J M; Trigger, S A

    2003-01-01

    We argue that dust immersed in a plasma sheath acts as a surfactant. By considering the momentum balance in a plasma sheath, we evaluate the dependence of the plasma surface pressure on the dust density. It is shown that the dust may reduce the surface pressure, giving rise to a sufficiently strong tangential force. The latter is capable of confining the dust layer inside the sheath in the direction perpendicular to the ion flow

  5. Investigation of laundering and dispersion approaches for silica and calcium phosphosilicate composite nanoparticles synthesized in reverse micelles

    Science.gov (United States)

    Tabakovic, Amra

    Nanotechnology, the science and engineering of materials at the nanoscale, is a booming research area with numerous applications in electronic, cosmetic, automotive and sporting goods industries, as well as in biomedicine. Composite nanoparticles (NPs) are of special interest since the use of two or more materials in NP design imparts multifunctionality on the final NP constructs. This is especially relevant for applications in areas of human healthcare, where the use of dye or drug doped composite NPs is expected to improve the diagnosis and treatment of cancer and other serious illnesses. Since the physicochemical properties of NP suspensions dictate the success of these systems in biomedical applications, especially drug delivery of chemotherapeutics, synthetic routes which offer precise control of NP properties, especially particle diameter and colloidal stability, are utilized to form a variety of composite NPs. Formation of NPs in reverse, or water-in-oil, micelles is one such synthetic approach. However, while the use of reverse micelles to form composite NPs offers precise control over NP size and shape, the post-synthesis laundering and dispersion of synthesized NP suspensions can still be a challenge. Reverse micelle synthetic approaches require the use of surfactants and low dielectric constant solvents, like hexane and cyclohexane, as the oil phase, which can compromise the biocompatibility and colloidal stability of the final composite NP suspensions. Therefore, appropriate dispersants and solvents must be used during laundering and dispersion to remove surfactant and ensure stability of synthesized NPs. In the work presented in this dissertation, two laundering and dispersion approaches, including packed column high performance liquid chromatography (HPLC) and centrifugation (sedimentation and redispersion), are investigated for silver core silica (Ag-SiO2) and calcium phosphosilicate (Caw(HxPO4)y(Si(OH)zOa) b · cH2O, CPS) composite NP suspensions

  6. MICROBIAL SURFACTANTS. I. GLYCOLIPIDS

    Directory of Open Access Journals (Sweden)

    Pirog T. Р.

    2014-02-01

    Full Text Available The review is devoted to surface-active glycolipids. The general characteristics, the physiological role of the rhamnolipids, trehalose lipids, sophorolipids, mannosylerythritol lipids and their traditional producers — the representatives of the genera Pseudozyma, Pseudomonas, Rhodococcus and Candida are given. The detailed analysis of the chemical structure, the stages of the biosynthesis and the regulation of some low molecular glycolipids are done. The own experimental data concerning the synthesis intensification, the physiological role and the practical use of Rhodococcus erythropolis IMV Ac-5017, Acinetobacter calcoaceticus IMV B-7241 and Nocardia vaccinii IMV B-7405 surfactants, which are a complex of the glyco-, phospho-, amino- and neutral lipids (glycolipids of all strains are presented by trehalose mycolates are summarized. It was found that R. erythropolis IMV Ac-5017, A. calcoaceticus IMV B-7241 and N. vaccinii IMV B-7405 surfactants have protective, antimicrobial and antiadhesive properties. It was shown that R. erythropolis IMV Ac-5017, A. calcoaceticus IMV B-7241 and N. vaccinii IMV B-7405 surfactants preparation of cultural liquid intensified the degradation of oil in water due to the activation of the natural petroleum-oxidizing microflora.

  7. Biodegradability of bacterial surfactants.

    Science.gov (United States)

    Lima, Tânia M S; Procópio, Lorena C; Brandão, Felipe D; Carvalho, André M X; Tótola, Marcos R; Borges, Arnaldo C

    2011-06-01

    This work aimed at evaluating the biodegradability of different bacterial surfactants in liquid medium and in soil microcosms. The biodegradability of biosurfactants by pure and mixed bacterial cultures was evaluated through CO(2) evolution. Three bacterial strains, Acinetobacter baumanni LBBMA ES11, Acinetobacter haemolyticus LBBMA 53 and Pseudomonas sp. LBBMA 101B, used the biosurfactants produced by Bacillus sp. LBBMA 111A (mixed lipopeptide), Bacillus subtilis LBBMA 155 (lipopeptide), Flavobacterium sp. LBBMA 168 (mixture of flavolipids), Dietzia Maris LBBMA 191(glycolipid) and Arthrobacter oxydans LBBMA 201(lipopeptide) as carbon sources in minimal medium. The synthetic surfactant sodium dodecyl sulfate (SDS) was also mineralized by these microorganisms, but at a lower rate. CO(2) emitted by a mixed bacterial culture in soil microcosms with biosurfactants was higher than in the microcosm containing SDS. Biosurfactant mineralization in soil was confirmed by the increase in surface tension of the soil aqueous extracts after incubation with the mixed bacterial culture. It can be concluded that, in terms of biodegradability and environmental security, these compounds are more suitable for applications in remediation technologies in comparison to synthetic surfactants. However, more information is needed on structure of biosurfactants, their interaction with soil and contaminants and scale up and cost for biosurfactant production.

  8. Preparation of Polymeric Micelles for use as Carriers of ...

    African Journals Online (AJOL)

    These micelles were characterized by dynamic light scattering, to measure the micelle diameter; by acid-base titration, to determine the percentage of carboxylic groups occupied by the tuberculostatic; by Sudan III solubility tests, to estimate the critical micelle concentration (CMC); and visual control and spectrophotometric ...

  9. Preparation of Polymeric Micelles for Use as Carriers of ...

    African Journals Online (AJOL)

    Erah

    Tropical Journal of Pharmaceutical Research, December 2007; 6 (4): 815-824 ... by the tuberculostatic; by Sudan III solubility tests, to estimate the critical micelle concentration (CMC); ... Furthermore, the micelles were stable in vitro, exhibiting a low level of CMC and stronger anti- ... that take the form of micelles 5, 6, 7, 8.

  10. "Non-equilibrium" block copolymer micelles with glassy cores: a predictive approach based on theory of equilibrium micelles.

    Science.gov (United States)

    Nagarajan, Ramanathan

    2015-07-01

    Micelles generated in water from most amphiphilic block copolymers are widely recognized to be non-equilibrium structures. Typically, the micelles are prepared by a kinetic process, first allowing molecular scale dissolution of the block copolymer in a common solvent that likes both the blocks and then gradually replacing the common solvent by water to promote the hydrophobic blocks to aggregate and create the micelles. The non-equilibrium nature of the micelle originates from the fact that dynamic exchange between the block copolymer molecules in the micelle and the singly dispersed block copolymer molecules in water is suppressed, because of the glassy nature of the core forming polymer block and/or its very large hydrophobicity. Although most amphiphilic block copolymers generate such non-equilibrium micelles, no theoretical approach to a priori predict the micelle characteristics currently exists. In this work, we propose a predictive approach for non-equilibrium micelles with glassy cores by applying the equilibrium theory of micelles in two steps. In the first, we calculate the properties of micelles formed in the mixed solvent while true equilibrium prevails, until the micelle core becomes glassy. In the second step, we freeze the micelle aggregation number at this glassy state and calculate the corona dimension from the equilibrium theory of micelles. The condition when the micelle core becomes glassy is independently determined from a statistical thermodynamic treatment of diluent effect on polymer glass transition temperature. The predictions based on this "non-equilibrium" model compare reasonably well with experimental data for polystyrene-polyethylene oxide diblock copolymer, which is the most extensively studied system in the literature. In contrast, the application of the equilibrium model to describe such a system significantly overpredicts the micelle core and corona dimensions and the aggregation number. The non-equilibrium model suggests ways to

  11. Stability of casein micelles in milk

    Science.gov (United States)

    Tuinier, R.; de Kruif, C. G.

    2002-07-01

    Casein micelles in milk are proteinaceous colloidal particles and are essential for the production of flocculated and gelled products such as yogurt, cheese, and ice-cream. The colloidal stability of casein micelles is described here by a calculation of the pair potential, containing the essential contributions of brush repulsion, electrostatic repulsion, and van der Waals attraction. The parameters required are taken from the literature. The results are expressed by the second osmotic virial coefficient and are quite consistent with experimental findings. It appears that the stability is mainly attributable to a steric layer of κ-casein, which can be described as a salted polyelectrolyte brush.

  12. Mixed micelles of sodium cholate and sodium dodecylsulphate 1:1 binary mixture at different temperatures--experimental and theoretical investigations.

    Directory of Open Access Journals (Sweden)

    Balázs Jójárt

    Full Text Available Micellisation process for sodium dodecyl sulphate and sodium cholate in 1∶1 molar ratio was investigated in a combined approach, including several experimental methods and coarse grained molecular dynamics simulation. The critical micelle concentration (cmc of mixed micelle was determined by spectrofluorimetric and surface tension measurements in the temperature range of 0-50°C and the values obtained agreed with each other within the statistical error of the measurements. In range of 0-25°C the cmc values obtained are temperature independent while cmc values were increased at higher temperature, which can be explained by the intensive motion of the monomers due to increased temperature. The evidence of existing synergistic effect among different constituent units of the micelle is indicated clearly by the interaction parameter (β1,2 calculated from cmc values according to Rubingh. As the results of the conductivity measurements showed the negative surface charges of the SDS-NaCA micelle are not neutralized by counterions. Applying a 10 µs long coarse-grained molecular dynamics simulation for system including 30-30 SDS and CA (with appropriate number of Na+ cations and water molecules we obtained semi-quantitative agreement with the experimental results. Spontaneous aggregation of the surfactant molecules was obtained and the key steps of the micelle formation are identified: First a stable SDS core was formed and thereafter due to the entering CA molecules the size of the micelle increased and the SDS content decreased. In addition the size distribution and composition as well as the shape and structure of micelles are also discussed.

  13. Preparation and evaluation of icariside II-loaded binary mixed micelles using Solutol HS15 and Pluronic F127 as carriers.

    Science.gov (United States)

    Hou, Jian; Wang, Jing; Sun, E; Yang, Lei; Yan, Hong-Mei; Jia, Xiao-Bin; Zhang, Zhen-Hai

    2016-11-01

    An effective anti-cancer drug, icariside II (IS), has been used to treat a variety of cancers in vitro. However, its poor aqueous solubility and permeability lead to low oral bioavailability. The aim of this work was to use Solutol®HS15 and Pluronic F127 as surfactants to develop novel mixed micelles to enhance the oral bioavailability of IS by improving permeability and inhibiting efflux. The IS-loaded mixed micelles were prepared using the method of ethanol thin-film hydration. The physicochemical properties, dissolution property, oral bioavailability of the male SD rats, permeability and efflux of Caco-2 transport models, and gastrointestinal safety of the mixed micelles were evaluated. The optimized IS-loaded mixed micelles showed that at 4:1 ratio of Solutol®HS15 and Pluronic F127, the particle size was 12.88 nm with an acceptable polydispersity index of 0.172. Entrapment efficiency (94.6%) and drug loading (9.7%) contributed to the high solubility (11.7 mg/mL in water) of IS, which increased about 900-fold. The SF-IS mixed micelle release profile showed a better sustained release property than that of IS. In Caco-2 cell monolayer models, the efflux ratio dramatically decreased by 83.5%, and the relative bioavailability of the mixed micelles (AUC 0-∞ ) compared with that of IS (AUC 0-∞ ) was 317%, indicating potential for clinical application. In addition, a gastrointestinal safety assay also provided reliable clinical evidence for the safe use of this micelle.

  14. Micellar Surfactant Association in the Presence of a Glucoside-based Amphiphile Detected via High-Throughput Small Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Stanic, Vesna [Brazilian Synchrotron Light Source, Campinas (Brazil); Broadbent, Charlotte [Columbia Univ., New York, NY (United States). Engineering Dept.; DiMasi, Elaine [Brookhaven National Lab. (BNL), Upton, NY (United States). Photon Sciences Division; Galleguillos, Ramiro [Lubrizol Advanced Materials, Cleveland, OH (United States); Woodward, Valerie [Lubrizol Advanced Materials, Cleveland, OH (United States)

    2016-11-14

    The interactions of mixtures of anionic and amphoteric surfactants with sugar amphiphiles were studied via high throughput small angle x-ray scattering (SAXS). The sugar amphiphile was composed of Caprate, Caprylate, and Oleate mixed ester of methyl glucoside, MeGCCO. Optimal surfactant interactions are sought which have desirable physical properties, which must be identified in a cost effective manner that can access the large phase space of possible molecular combinations. X-ray scattering patterns obtained via high throughput SAXS can probe a combinatorial sample space and reveal the incorporation of MeGCCO into the micelles and the molecular associations between surfactant molecules. Such data make it possible to efficiently assess the effects of the new amphiphiles in the formulation. A specific finding of this study is that formulations containing comparatively monodisperse and homogeneous surfactant mixtures can be reliably tuned by addition of NaCl, which swells the surfactant micelles with a monotonic dependence on salt concentration. In contrast, the presence of multiple different surfactants destroys clear correlations with NaCl concentration, even in otherwise similar series of formulations.

  15. ''Over the horizon'' SANS: Measurements on near-surface Poiseuille shear-induced ordering of dilute solutions of threadlike micelles

    International Nuclear Information System (INIS)

    Hamilton, W.A.; Butler, P.D.; Hayter, J.B.; Magid, L.J.; Kreke, P.J.

    1995-01-01

    Although the behavior of a fluid under shear near a surface can be expected to be critically important to its drag and lubrication properties, most shear measurements to date have been of the bulk. This paper outlines the use of a specially developed Poiseuille shear cell at grazing incidence to measure the small-angle neutron scattering (SANS) signal from the first few tens of microns in the interfacial region. The authors illustrate the technique with measurements made on the near-surface ordering in flow past a quartz surface of dilute surfactant solutions comprising highly extended self-assembling ''threadlike'' micelles

  16. Surfactant-Mediated Growth Revisited

    International Nuclear Information System (INIS)

    Meyerheim, H. L.; Sander, D.; Popescu, R.; Pan, W.; Kirschner, J.; Popa, I.

    2007-01-01

    The x-ray structure analysis of the oxygen-surfactant-mediated growth of Ni on Cu(001) identifies up to 0.15 monolayers of oxygen in subsurface octahedral sites. This questions the validity of the general view that surfactant oxygen floats on top of the growing Ni film. Rather, the surfactant action is ascribed to an oxygen-enriched zone extending over the two topmost layers. Surface stress measurements support this finding. Our results have important implications for the microscopic understanding of surfactant-mediated growth and the change of the magnetic anisotropy of the Ni films

  17. Spontaneous vesicle phase formation by pseudogemini surfactants in aqueous solutions.

    Science.gov (United States)

    Sun, Nan; Shi, Lijuan; Lu, Fei; Xie, Shuting; Zheng, Liqiang

    2014-08-14

    The phase behavior of a kind of pseudogemini surfactant in aqueous solutions, formed by the mixture of sodium dodecyl benzene sulfonate (SDBS) and butane-1,4-bis (methylimidazolium bromide) ([mim-C4-mim]Br2) or butane-1,4-bis(methylpyrrolidinium bromide) ([mpy-C4-mpy]Br2) in a molar ratio of 2 : 1, is reported in the present work. When [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 is mixed with SDBS in aqueous solutions, one cationic [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 molecule "bridges" two SDBS molecules by noncovalent interactions (e.g. electrostatic, π-π stacking, and σ-π interactions), behaving like a pseudogemini surfactant. Vesicles can be formed by this kind of pseudogemini surfactant, determined by freeze-fracture transmission electron microscopy (FF-TEM) or cryogenic-transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS). The mixed system of sodium dodecyl sulfate (SDS) with [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 was also constructed, and only micelles were observed. We infer that a pseudogemini surfactant is formed under the synergic effect of electrostatic, π-π stacking, and σ-π interactions in the SDBS/[mim-C4-mim]Br2/H2O system, while electrostatic attraction and hydrophobic interactions may provide the directional force for vesicle formation in the SDBS/[mpy-C4-mpy]Br2/H2O system.

  18. Adsorption of surfactants and polymers at interfaces

    Science.gov (United States)

    Rojas, Orlando Jose

    Surface tension and high-resolution laser light scattering experiments were used to investigate the adsorption of isomeric sugar-based surfactants at the air/liquid interface in terms of surfactant surface packing and rheology. Soluble monolayers of submicellar surfactant solutions exhibited a relatively viscous behavior. It was also proved that light scattering of high-frequency thermally-induced capillary waves can be utilized to study surfactant exchange between the surface and the bulk solution. Such analysis revealed the existence of a diffusional relaxation mechanism. A procedure based on XPS was developed for quantification, on an absolute basis, of polymer adsorption on mica and Langmuir-Blodgett cellulose films. The adsorption of cationic polyelectrolytes on negatively-charged solid surfaces was highly dependent on the polymer ionicity. It was found that the adsorption process is driven by electrostatic mechanisms. Charge overcompensation (or charge reversal) of mica occurred after adsorption of polyelectrolytes of ca. 50% charge density, or higher. It was demonstrated that low-charge-density polyelectrolytes adsorb on solid surfaces with an extended configuration dominated by loops and tails. In this case the extent of adsorption is limited by steric constraints. The conformation of the polyelectrolyte in the adsorbed layer is dramatically affected by the presence of salts or surfactants in aqueous solution. The phenomena which occur upon increasing the ionic strength are consistent with the screening of the electrostatic attraction between polyelectrolyte segments and solid surface. This situation leads to polyelectrolyte desorption accompanied by both an increase in the layer thickness and the range of the steric force. Adsorbed polyelectrolytes and oppositely charged surfactants readily associate at the solid/liquid interface. Such association induces polyelectrolyte desorption at a surfactant concentration which depends on the polyelectrolyte charge

  19. Electrostatic Screening and Charge Correlation Effects in Micellization of Ionic Surfactants

    KAUST Repository

    Jusufi, Arben

    2009-05-07

    We have used atomistic simulations to study the role of electrostatic screening and charge correlation effects in self-assembly processes of ionic surfactants into micelles. Specifically, we employed grand canonical Monte Carlo simulations to investigate the critical micelle concentration (cmc), aggregation number, and micellar shape in the presence of explicit sodium chloride (NaCl). The two systems investigated are cationic dodecyltrimethylammonium chloride (DTAC) and anionic sodium dodecyl sulfate (SDS) surfactants. Our explicit-salt results, obtained from a previously developed potential model with no further adjustment of its parameters, are in good agreement with experimental data for structural and thermodynamic micellar properties. We illustrate the importance of ion correlation effects by comparing these results with a Yukawa-type surfactant model that incorporates electrostatic screening implicitly. While the effect of salt on the cmc is well-reproduced even with the implicit Yukawa model, the aggregate size predictions deviate significantly from experimental observations at low salt concentrations. We attribute this discrepancy to the neglect of ion correlations in the implicit-salt model. At higher salt concentrations, we find reasonable agreement of the Yukawa model with experimental data. The crossover from low to high salt concentrations is reached when the electrostatic screening length becomes comparable to the headgroup size. © 2009 American Chemical Society.

  20. Effect of protein-surfactant interactions on aggregation of β-lactoglobulin.

    Science.gov (United States)

    Hansted, Jon G; Wejse, Peter L; Bertelsen, Hans; Otzen, Daniel E

    2011-05-01

    The milk protein β-lactoglobulin (βLG) dominates the properties of whey aggregates in food products. Here we use spectroscopic and calorimetric techniques to elucidate how anionic, cationic and non-ionic surfactants interact with bovine βLG and modulate its heat-induced aggregation. Alkyl trimethyl ammonium chlorides (xTAC) strongly promote aggregation, while sodium alkyl sulfates (SxS) and alkyl maltopyranosides (xM) reduce aggregation. Sodium dodecyl sulfate (SDS) binds to non-aggregated βLG in several steps, but reduction of aggregation was associated with the first binding step, which occurs far below the critical micelle concentration. In contrast, micellar concentrations of xMs are required to reduce aggregation. The ranking order for reduction of aggregation (normalized to their tendency to self-associate) was C10-C12>C8>C14 for SxS and C8>C10>C12>C14>C16 for xM. xTAC promote aggregation in the same ranking order as xM reduce it. We conclude that SxS reduce aggregation by stabilizing the protein's ligand-bound state (the melting temperature t(m) increases by up to 10°C) and altering its charge potential. xM monomers also stabilize the protein's ligand-bound state (increasing t(m) up to 6°C) but in the absence of charged head groups this is not sufficient by itself to prevent aggregation. Although micelles of both anionic and non-ionic surfactants destabilize βLG, they also solubilize unfolded protein monomers, leaving them unavailable for protein-protein association and thus inhibiting aggregation. Cationic surfactants promote aggregation by a combination of destabilization and charge neutralization. The food compatible surfactant sodium dodecanoate also inhibited aggregation well below the cmc, suggesting that surfactants may be a practical way to modulate whey protein properties. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Lateral transport of solutes in microfluidic channels using electrochemically generated gradients in redox-active surfactants.

    Science.gov (United States)

    Liu, Xiaoyang; Abbott, Nicholas L

    2011-04-15

    We report principles for a continuous flow process that can separate solutes based on a driving force for selective transport that is generated by a lateral concentration gradient of a redox-active surfactant across a microfluidic channel. Microfluidic channels fabricated with gold electrodes lining each vertical wall were used to electrochemically generate concentration gradients of the redox-active surfactant 11-ferrocenylundecyl-trimethylammonium bromide (FTMA) in a direction perpendicular to the flow. The interactions of three solutes (a hydrophobic dye, 1-phenylazo-2-naphthylamine (yellow AB), an amphiphilic molecule, 2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine (BODIPY C(5)-HPC), and an organic salt, 1-methylpyridinium-3-sulfonate (MPS)) with the lateral gradients in surfactant/micelle concentration were shown to drive the formation of solute-specific concentration gradients. Two distinct physical mechanisms were identified to lead to the solute concentration gradients: solubilization of solutes by micelles and differential adsorption of the solutes onto the walls of the microchannels in the presence of the surfactant concentration gradient. These two mechanisms were used to demonstrate delipidation of a mixture of BODIPY C(5)-HPC (lipid) and MPS and purification of BODIPY C(5)-HPC from a mixture of BODIPY C(5)-HPC and yellow AB. Overall, the results of this study demonstrate that lateral concentration gradients of redox-active surfactants formed within microfluidic channels can be used to transport solutes across the microfluidic channels in a solute-dependent manner. The approach employs electrical potentials (solutions having high ionic strength (>0.1M), and offers the basis of continuous processes for the purification or separation of solutes in microscale systems. © 2011 American Chemical Society

  2. Surfactant phosphatidylcholine metabolism and surfactant function in preterm, ventilated lambs

    International Nuclear Information System (INIS)

    Jobe, A.H.; Ikegami, M.; Seidner, S.R.; Pettenazzo, A.; Ruffini, L.

    1989-01-01

    Preterm lambs were delivered at 138 days gestational age and ventilated for periods up to 24 h in order to study surfactant metabolism and surfactant function. The surfactant-saturated phosphatidylcholine pool in the alveolar wash was 13 +/- 4 mumol/kg and did not change from 10 min to 24 h after birth. Trace amounts of labeled natural sheep surfactant were mixed with fetal lung fluid at birth. By 24 h, 80% of the label had become lung-tissue-associated, yet there was no loss of label from phosphatidylcholine in the lungs when calculated as the sum of the lung tissue plus alveolar wash. De novo synthesized phosphatidylcholine was labeled with choline given by intravascular injection at 1 h of age. Labeled phosphatidylcholine accumulated in the lung tissue linearly to 24 h, and the labeled phosphatidylcholine moved through lamellar body to alveolar pools. The turnover time for alveolar phosphatidylcholine was estimated to be about 13 h, indicating an active metabolic pool. A less surface-active surfactant fraction recovered as a supernatant after centrifugation of the alveolar washes at 40,000 x g increased from birth to 10 min of ventilation, but no subsequent changes in the distribution of surfactant phosphatidylcholine in surfactant fractions occurred. The results were consistent with recycling pathway(s) that maintained surface-active surfactant pools in preterm ventilated lambs

  3. Reverse micelles as a tool for probing solvent modulation of protein dynamics: Reverse micelle encapsulated hemoglobin☆

    OpenAIRE

    Roche, Camille J.; Dantsker, David; Heller, Elizabeth R.; Sabat, Joseph E.; Friedman, Joel M.

    2013-01-01

    Hydration waters impact protein dynamics. Dissecting the interplay between hydration waters and dynamics requires a protein that manifests a broad range of dynamics. Proteins in reverse micelles (RMs) have promise as tools to achieve this objective because the water content can be manipulated. Hemoglobin is an appropriate tool with which to probe hydration effects. We describe both a protocol for hemoglobin encapsulation in reverse micelles and a facile method using PEG and cosolvents to mani...

  4. Partition thermodynamics of ionic surfactants between phosphatidylcholine vesicle and water phases

    Science.gov (United States)

    Chu, Shin-Chi; Hung, Chia-Hui; Wang, Shun-Cheng; Tsao, Heng-Kwong

    2003-08-01

    The partition of ionic surfactants (sodium alkyl sulfate and alkyl trimethyl ammonium bromide) between phosphatidylcholine vesicles and aqueous phase is investigated by simple conductometry under different temperatures. The experimental results can be well represented by the proposed regular solution theory and the thermodynamic parameters satisfy the thermodynamic consistency. The deviation from ideal partition is manifested through the effective interaction energy between lipid and surfactant wb, which is O(kT) large. It is found that wb rises as the alkyl chain is decreased for a specified head group. This is attributed to significant mismatch of chain lengths between surfactant and lipid molecules. The partition coefficient K declines with increasing temperature. The energy barrier from bilayer to aqueous phase, Δμ/kT∝ln K, is in the range of 16-26 kJ/mol. As the alkyl chain length is decreased for a given head group, Δμ is lowered by 1.3-1.5 kJ/mol per methylene group. Two independent analyses are employed to confirm this result. Using the thermodynamic parameters determined from experiments, the internal energy, entropy, and free energy of the partition process can be derived. Partition is essentially driven by the internal energy gain. The solubilizing ability, which is represented by the maximum surfactant-lipid ratio in the bilayer, Reb also decreases in accord with the K parameter. It is because the change in temperature influences the surfactant incorporation into the bilayer more than the formation of micelles.

  5. Micelle-encapsulated fullerenes in aqueous electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Ala-Kleme, T., E-mail: timo.ala-kleme@utu.fi [Department of Chemistry, University of Turku, 20014 Turku (Finland); Maeki, A.; Maeki, R.; Kopperoinen, A.; Heikkinen, M.; Haapakka, K. [Department of Chemistry, University of Turku, 20014 Turku (Finland)

    2013-03-15

    Different micellar particles Mi(M{sup +}) (Mi=Triton X-100, Triton N-101 R, Triton CF-10, Brij-35, M{sup +}=Na{sup +}, K{sup +}, Cs{sup +}) have been prepared in different aqueous H{sub 3}BO{sub 3}/MOH background electrolytes. It has been observed that these particles can be used to disperse the highly hydrophobic spherical [60]fullerene (1) and ellipsoidal [70]fullerene (2). This dispersion is realised as either micelle-encapsulated monomers Mi(M{sup +})1{sub m} and Mi(M{sup +})2{sub m} or water-soluble micelle-bound aggregates Mi(M{sup +})1{sub agg} and Mi(M{sup +})2{sub agg}, where especially the hydration degree and polyoxyethylene (POE) thickness of the micellar particle seems to play a role of vital importance. Further, the encapsulation microenvironment of 1{sub m} was found to depend strongly on the selected monovalent electrolyte cation, i.e., the encapsulated 1{sub m} is accommodated in the more hydrophobic microenvironment the higher the cationic solvation number is. - Highlights: Black-Right-Pointing-Pointer Different micellar particles is used to disperse [60]fullerene and [70]fullerene. Black-Right-Pointing-Pointer Fullerene monomers or aggregates are dispersed encaging or bounding by micelles. Black-Right-Pointing-Pointer Effective facts are hydration degree and polyoxyethylene thickness of micelle.

  6. Hyaluronan polymeric micelles for topical drug delivery

    Czech Academy of Sciences Publication Activity Database

    Šmejkalová, D.; Muthný, T.; Nešporová, K.; Hermannová, M.; Achbergerová, E.; Huerta-Angelesa, G.; Marek Svoboda, M.; Čepa, M.; Machalová, V.; Luptáková, Dominika; Velebný, V.

    2017-01-01

    Roč. 156, JAN 20 (2017), s. 86-96 ISSN 0144-8617 Institutional support: RVO:61388971 Keywords : Skin penetration * Polymeric micelle * Hyaluronan Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 4.811, year: 2016

  7. SANS analysis of aqueous ionic perfluoropolyether micelles

    CERN Document Server

    Gambi, C M C; Chittofrati, A; Pieri, R; Baglioni, P; Teixeira, J

    2002-01-01

    Preliminary SANS results of ionic chlorine terminated perfluoropolyether micelles in water are given. The experimental spectra have been analyzed by a two-shell ellipsoidal model for the micellar form factor and a screened Coulombic plus hard-sphere repulsion potential for the structure factor. (orig.)

  8. Co-assembly towards Janus micelles

    NARCIS (Netherlands)

    Voets, I.K.; Leermakers, F.A.M.; Keizer, de A.; Charlaganov, M.; Cohen Stuart, M.A.

    2011-01-01

    In this paper, we report on our recent findings concerning the structure of complex coacervate core micelles composed of two types of (complementary) block copolymers. Both copolymers have a polyelectrolyte (one cationic and the other anionic) block combined with a neutral one. The opposite charges

  9. Neutral Polymeric Micelles for RNA Delivery

    Science.gov (United States)

    Lundy, Brittany B.; Convertine, Anthony; Miteva, Martina; Stayton, Patrick S.

    2013-01-01

    RNA interference (RNAi) drugs have significant therapeutic potential but delivery systems with appropriate efficacy and toxicity profiles are still needed. Here, we describe a neutral, ampholytic polymeric delivery system based on conjugatable diblock polymer micelles. The diblock copolymer contains a hydrophilic poly[N-(2-hydroxypropyl) methacrylamide-co-N-(2-(pyridin-2- yldisulfanyl)ethyl)methacrylamide) (poly[HPMA-co-PDSMA]) segment to promote aqueous stability and facilitate thiol-disulfide exchange reactions, and a second ampholytic block composed of propyl acrylic acid (PAA), dimethylaminoethyl methacrylate (DMAEMA), and butyl methacrylate (BMA). The poly[(HPMA-co-PDSMA)-b-(PAA-co-DMAEMA-co-BMA)] was synthesized using Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization with an overall molecular weight of 22,000 g/mol and a PDI of 1.88. Dynamic light scattering and fluorescence measurements indicated that the diblock copolymers self-assemble under aqueous conditions to form polymeric micelles with a hydrodynamic radius and critical micelle concentration of 25 nm and 25 μg/mL respectively. Red blood cell hemolysis experiments show that the neutral hydrophilic micelles have potent membrane destabilizing activity at endosomal pH values. Thiolated siRNA targeting glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was directly conjugated to the polymeric micelles via thiol exchange reactions with the pyridal disulfide groups present in the micelle corona. Maximum silencing activity in HeLa cells was observed at a 1:10 molar ratio of siRNA to polymer following a 48 h incubation period. Under these conditions 90 % mRNA knockdown and 65 % and protein knockdown of at 48 h was achieved with negligible toxicity. In contrast the polymeric micelles lacking a pH-responsive endosomalytic segment demonstrated negligible mRNA and protein knockdown under these conditions. The potent mRNA knockdown and excellent biocompatibility of the neutral siRNA conjugates

  10. Spectroscopic investigation of the pH controlled inclusion of doxycycline and oxytetracycline antibiotics in cationic micelles and their magnesium driven release.

    Science.gov (United States)

    Cesaretti, Alessio; Carlotti, Benedetta; Gentili, Pier Luigi; Clementi, Catia; Germani, Raimondo; Elisei, Fausto

    2014-07-24

    This work presents a steady-state and time-resolved UV-visible spectroscopic investigation of two antibiotics belonging to the family of tetracyclines (doxycycline and oxytetracycline) in the micellar medium provided by p-dodecyloxybenzyltrimethylammonium bromide (pDoTABr). The spectroscopic analysis has been performed in absorption and emission with femtosecond time resolution, and at pH 5.0 and 8.7 where doxycycline and oxytetracycline are present in their neutral-zwitterionic and monoanionic forms, respectively. The experimental data have been processed by sophisticated data mining methods such as global/target analysis and the maximum entropy method. The results unambiguously indicate that, when doxycycline and oxytetracycline are in their zwitterionic form, they are entrapped within the micelle, while when they are in their monoanionic form, they preferentially show a strong one-to-one interaction with the positively charged surfactant heads. Thus, the pH of the solution controls the inclusion of the investigated drugs into the micelle. When the drugs are entrapped inside the micelles, their spectroscopic and dynamical properties after photoexcitation change appreciably. Interestingly, the entrapped drugs are still able to strongly bind Mg(2+) cations, crucial in determining the biological functioning of tetracyclines. The femtosecond resolved measurements reveal that the drugs are efficiently pulled out of the micelles by Mg(2+). In fact, magnesium-tetracycline complexes are detected in the aqueous phase. The present study suggests the potential promising use of ammonium surfactant micelles embedding doxycycline and oxytetracycline as "smart" drug delivery systems allowing their pH controlled inclusion and Mg(2+) induced release.

  11. ADSORPTION OF SURFACTANT ON CLAYS

    Science.gov (United States)

    Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

  12. Perfectly Wetting Mixtures of Surfactants from Renewable Resources: The Interaction and Synergistic Effects on Adsorption and Micellization.

    Science.gov (United States)

    Szumała, Patrycja; Mówińska, Alicja

    This paper presents a study of the surface properties of mixtures of surfactants originating from renewable sources, i.e., alkylpolyglucoside (APG), ethoxylated fatty alcohol (AE), and sodium soap (Na soap). The main objective was to optimize the surfactant ratio which produces the highest wetting properties during the analysis of the solution of the individual surfactants, two- and three-component mixtures, and at different pH values. The results showed the existence of a synergistic effect in lowering the interfacial tension, critical micelle concentration and the formation of mixed micelles in selected solutions. We found that best wetting properties were measured for the binary AE:APG mixtures. It has been demonstrated that slightly lower contact angles values were observed on Teflon and glass surfaces for the AE:APG:soap mixtures but the results were obtained for higher concentration of the components. In addition, all studied solutions have very good surface properties in acidic, basic and neural media. However, the AE:soap (molar ratio of 1:2), AE:APG (2:1) and AE:APG:soap (1:1:1) compositions improved their wetting power at pH 7 on the aluminium and glass surfaces, as compared to solutions at other pH values tested (selected Θ values close to zero-perfectly wetting liquids). All described effects detected would allow less surfactant to be used to achieve the maximum capacity of washing, wetting or solubilizing while minimizing costs and demonstrating environmental care.

  13. Solubilization and mineralization of polycyclic aromatic hydrocarbons by Pseudomonas putida in the presence of surfactant

    International Nuclear Information System (INIS)

    Doong Rueyan; Lei Wengang

    2003-01-01

    The solubilization and mineralization of polycyclic aromatic hydrocarbons (PAHs) in a soil system amended with different surfactants was examined. Mineralization experiments were conducted with the addition of [ 14 C]pyrene. An inoculum of the PAH-degrading microorganism, Pseudomonas putida, was investigated for its sensitivity towards four non-ionic and one anionic surfactants with different polyoxyethylene (POE) chain lengths. The addition of surfactant was found to enhance the bioavailability of naphthalene, phenanthrene and pyrene with efficiencies ranging from 21.1 to 60.6%, 33.3 to 62.8% and 26.8 to 70.9%, respectively. The enhanced efficiency followed the order of Brij 30, Triton X-100, Tween 80, and Brij 35, which is correlated with the polyoxyethylene chain of the surfactants. Brij 35 and Tween 80 inhibited the growth of P. putida. However, microorganisms can utilize Triton X-100 and Brij 30 as the sole carbon and energy sources at concentrations above CMC values. In the aqueous system without the addition of surfactants, microorganisms could mineralize [ 14 C]pyrene to 14 CO 2 which corresponds to 28% of mineralization. The addition of surfactants decreased the mineralization rate of pyrene. Also, the fraction of the micellar-phase pyrene that can be directly biodegraded decreased as the concentration of micelle increases. However, the mineralization rate can be enhanced by the amendment of Brij 30 when soil was applied to the cultures. This suggests that biodegradable surfactants can be applicable for increasing the bioavailability and mineralization of PAHs in soil systems

  14. Affect

    NARCIS (Netherlands)

    Cetinic, M.; Diamanti, J.; Szeman, I.; Blacker, S.; Sully, J.

    2017-01-01

    This chapter historicizes four divergent but historically contemporaneous genres of affect theory – romantic, realist, speculative, and materialist. While critics credited with the turn to affect in the 1990s wrote largely in the wake of poststructuralism from the perspective of gender and queer

  15. Neutron reflectivity studies of electric field driven structural transformations of surfactants

    CERN Document Server

    Majewski, J; Burgess, I; Zamlynny, V; Szymanski, G; Lipkowski, J; Satija, S

    2002-01-01

    We employed electrochemical methods together with in situ neutron reflectometry to describe the aggregation of organic surfactant molecules at a solid-liquid interface. The neutron reflectometry allowed us to determine the surface coverage, thickness, roughness and the relative positions of the aggregates. We found that the applied electric field may be used to reversibly manipulate the architecture of the organic molecules: from uniform monolayers to adsorbed hemi-micelles. These studies are expected to provide a new insight into the roles played by entropic and electrostatic forces in complex fluids or biomaterials. (orig.)

  16. An Asymptotic Theory for the Re-Equilibration of a Micellar Surfactant Solution

    KAUST Repository

    Griffiths, I. M.; Bain, C. D.; Breward, C. J. W.; Chapman, S. J.; Howell, P. D.; Waters, S. L.

    2012-01-01

    Micellar surfactant solutions are characterized by a distribution of aggregates made up predominantly of premicellar aggregates (monomers, dimers, trimers, etc.) and a region of proper micelles close to the peak aggregation number, connected by an intermediate region containing a very low concentration of aggregates. Such a distribution gives rise to a distinct two-timescale reequilibration following a system dilution, known as the t1 and t2 processes, whose dynamics may be described by the Becker-Döring equations. We use a continuum version of these equations to develop a reduced asymptotic description that elucidates the behavior during each of these processes.© 2012 Society for Industrial and Applied Mathematics.

  17. Gemini Surfactants Based on Bis-Imidazolium Alkoxy Derivatives as Effective Agents for Delivery of Nucleic Acids: A Structural and Spectroscopic Study.

    Directory of Open Access Journals (Sweden)

    Zuzanna Pietralik

    Full Text Available The success rate of gene therapy depends on the efficient transfection of genetic material into cells. The golden mean between harmlessness and high effectiveness can be provided by synthetic lipid-like molecules that are similar to the components of biological membranes. Cationic gemini surfactants are one such moiety and because of their favourable physicochemical properties (double positive electric charge, reduced toxicity, low values of critical micelle concentration, they show great potential as delivery system components for genetic material in gene therapy. The aim of this study was to investigate the process of the complexation of cationic gemini surfactants with nucleic acids: double-stranded DNA of different sizes (21 bp, ~185 bp, ~20 kbp and siRNA (21 bp. The tested series of dicationic surfactants consists of bis-imidazolium quaternary salts with varying lengths of hydrophobic side chains (m = 5, 6, 7, 8, 9, 11, 12, 14, 16. On the basis of the data obtained by circular dichroism spectroscopy and electrophoresis, we concluded that the studied gemini surfactants with long side chains effectively bind nucleic acids at low concentrations, which leads to the formation of stable lipoplexes. Images obtained by atomic force microscopy also confirmed the formation of vesicular structures, i.e., complexes between DNA and surfactants. The cytotoxicity of selected surfactants was also tested on HeLa cells. The surfactant toxicity significantly depends on surfactant geometry (the length of hydrophobic chain.

  18. A study on the interaction of horse heart cytochrome c with some conventional and ionic liquid surfactants probed by ultraviolet-visible and fluorescence spectroscopic techniques.

    Science.gov (United States)

    Mondal, Satyajit; Das, Bijan

    2018-06-05

    The interactions of a protein cytochrome c with some selected conventional and ionic liquid surfactants have been investigated at pH7.4 using ultraviolet-visible and fluorescence spectroscopic techniques. We used four conventional surfactants - cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DTAB), sodium N-dodecanoylsarcosinate (SDDS), and N-decanoyl-N-methylglucamine (Mega 10), and a surface active ionic liquid 1-hexadecyl-3-methylimidazolium chloride (C 16 MeImCl). All the investigated surfactants were found to induce an unfolding of the protein cytochrome c. In presence of CTAB, SDDS and C 16 MeImCl, the heme iron atom was found to loose methionine from its axial position. Differential binding of the surfactant monomers and their micelles to the protein molecules was inferred. The ionic surfactants were found to be more effective than the nonionic one in unfolding the investigated protein. However, the extent of binding of CTAB/C 16 MeImCl to cytochrome c reaches a plateau past the critical micellization concentration (cmc) of the surfactant. For each of the cytochrome c-DTAB, cytochrome c-SDDS and cytochrome c-Mega 10 system, although there exists an inflection in the surfactant-binding, saturation point could not be detected. It has been demonstrated from the ultraviolet-visible spectral studies that the oxidation state of iron in cytochrome c does not change when the protein binds with the investigated surfactants. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. A study on the interaction of horse heart cytochrome c with some conventional and ionic liquid surfactants probed by ultraviolet-visible and fluorescence spectroscopic techniques

    Science.gov (United States)

    Mondal, Satyajit; Das, Bijan

    2018-06-01

    The interactions of a protein cytochrome c with some selected conventional and ionic liquid surfactants have been investigated at pH 7.4 using ultraviolet-visible and fluorescence spectroscopic techniques. We used four conventional surfactants - cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DTAB), sodium N-dodecanoylsarcosinate (SDDS), and N-decanoyl-N-methylglucamine (Mega 10), and a surface active ionic liquid 1-hexadecyl-3-methylimidazolium chloride (C16MeImCl). All the investigated surfactants were found to induce an unfolding of the protein cytochrome c. In presence of CTAB, SDDS and C16MeImCl, the heme iron atom was found to loose methionine from its axial position. Differential binding of the surfactant monomers and their micelles to the protein molecules was inferred. The ionic surfactants were found to be more effective than the nonionic one in unfolding the investigated protein. However, the extent of binding of CTAB/C16MeImCl to cytochrome c reaches a plateau past the critical micellization concentration (cmc) of the surfactant. For each of the cytochrome c-DTAB, cytochrome c-SDDS and cytochrome c-Mega 10 system, although there exists an inflection in the surfactant-binding, saturation point could not be detected. It has been demonstrated from the ultraviolet-visible spectral studies that the oxidation state of iron in cytochrome c does not change when the protein binds with the investigated surfactants.

  20. Batch and continuous extraction of bromelain enzyme by reversed micelles

    Directory of Open Access Journals (Sweden)

    Ana Maria Frattini Fileti

    2009-10-01

    Full Text Available The main aim of this study was to optimize the conditions for bromelain extraction by reversed micelles from pineapple juice (Ananas comosus. The purification was carried out in batch extraction and a micro-column with pulsed caps for continuous extraction. The cationic micellar solution was made of BDBAC as a surfactant, isooctane as a solvent and hexanol as a co-solvent. For the batch process, a purification factor of 3 times at the best values of surfactant agent, co-solvent and salt concentrations, pH of the back and forward extractions were, 100 mM, 10% v/v, 1 M, 3.5 and 8, respectively. For the continuous operation, independent variables optimal point was determined: ratio between light phase flow rate and total flow rate equal to 0.67 and 1 second for the time interval between the pulses. This optimal point led to a productivity of 1.29 mL/min and a purification factor of 4.96.Este trabalho teve como objetivo principal otimizar as condições para extração da bromelina do suco do abacaxi (Ananas comosus por micelas reversas. A purificação foi feita usando o processo de extração em batelada e contínuo, este último em uma micro-coluna de campânulas pulsantes. A solução micelar catiônica foi preparada com o surfactante BDBAC, i-octano como solvente e hexanol como co-solvente. Na extração em batelada encontrou-se um fator de purificação de 3 vezes, e seus melhores valores de concentração do agente surfactante, co-solvente e sal, de pH da re-extração e extração, foram respectivamente iguais a: 100 mM, 10% v/v, 1 M, 3,5 e 8. Para a operação contínua, as variáveis independentes ótimas foram: 0,67 para a razão entre as taxas de fluxos da fase leve e a total e 1 s para o intervalo de tempo entre pulsos das campânulas. Este ponto ótimo leva a uma produtividade de 1,29 mL/min e a um fator de purificação igual a 4,96.

  1. A Simple Two-Step Cloud Point Extraction Process for Removing Fluorescent Whitening Agents VBL in Industrial Wastewater and Recycling of Surfactant.

    Science.gov (United States)

    Han, Juan; Tang, Xu; Wang, Yun; Li, Jing; Ni, Liang; Wang, Lei

    2017-03-01

      With the enhancement of people's environmental consciousness, the treatment of wastewater was studied as the focus of this paper. Here we present a simple two-step extraction to realize efficient separation of fluorescent whitening agents VBL and cyclic utilization of surfactant to reduce the cost of wastewater treatment and environmental pollution. Firstly, the removal of VBL has been achieved by CPE using TX-114 as nonionic surfactant. The results showed that complete extraction was possible using 1% (w/w) TX-114 for VBL concentration not exceeding 17.5 mg/L, otherwise using a higher concentration of 1.5% (w/w) TX-114. Then the surfactant from the coacervate phase was recycled by changing the potential difference between phases. The morphology of micelles and solubilization mechanism of VBL were demonstrated through the observation of a fluorescent microscope. This method was successfully used to remove the VBL from wastewater sample and the surfactant could be reused several times.

  2. Comparison of micelle structure of glycolipids with different head groups by small angle neutron scattering

    International Nuclear Information System (INIS)

    He, Lizhong; Middelberg, Anton; Hartmann, Thorsten; Niemeyer, Bernd; Garamus, V.M.; Willumeit, Regine

    2005-01-01

    Full text: Glycolipids such as n-alkyl- beta-D-glucopyranoside and n-alkyl- beta-D-maltopyranoside can self-assemble into different structures depending on solution conditions. Their amphiphilic properties enable them to serve as biosurfactants in biology and biotechnology, especially for solubilizing membrane proteins. The physicochemical properties of glycolipids have attracted attentions from several research groups, aiming to better understand their application in biological and environmental processes. For example, small angle neutron and X-ray scattering have been used to study micelle structures formed by glycolipids. Our previous work has shown that n-octyl-beta- D-glucopyranoside and n-octyl- beta-D-maltopyranoside form micelles with different structure, suggesting an important role of the sugar head group in micelle formation. In the present work, we further compare micelle structures of n-octyl- beta-Dglucopyranoside and n-octyl- beta-D-galactopyranoside. These two glycolipids have the same hydrophobic tail and their head sugar groups differ only in the conformation with one hydroxyl group pointing to different direction. Our SANS data together with phase behaviours reported by other group have suggested that a slight alteration of head group conformation can significantly affect self-assembly of glycolipids. (authors)

  3. MICROBIAL SURFACTANTS IN ENVIRONMENTAL TECHNOLOGIES

    Directory of Open Access Journals (Sweden)

    T. P. Pirog

    2015-08-01

    Full Text Available It was shown literature and own experimental data concerning the use of microbial surface active glycolipids (rhamno-, sophoro- and trehalose lipids and lipopeptides for water and soil purification from oil and other hydrocarbons, removing toxic heavy metals (Cu2+, Cd2+, Ni2+, Pb2+, degradation of complex pollution (oil and other hydrocarbons with heavy metals, and the role of microbial surfactants in phytoremediation processes. The factors that limit the use of microbial surfactants in environmental technologies are discussed. Thus, at certain concentrations biosurfactant can exhibit antimicrobial properties and inhibit microorganisms destructing xenobiotics. Microbial biodegradability of surfactants may also reduce the effectiveness of bioremediation. Development of effective technologies using microbial surfactants should include the following steps: monitoring of contaminated sites to determine the nature of pollution and analysis of the autochthonous microbiota; determining the mode of surfactant introduction (exogenous addition of stimulation of surfactant synthesis by autochthonous microbiota; establishing an optimal concentration of surfactant to prevent exhibition of antimicrobial properties and rapid biodegradation; research both in laboratory and field conditions.

  4. Particle-size dependent sorption and desorption of pesticides within a water-soil-nonionic surfactant system.

    Science.gov (United States)

    Wang, Peng; Keller, Arturo A

    2008-05-01

    Although nonionic surfactants have been considered in surfactant-aided soil washing systems, there is little information on the particle-size dependence of these processes, and this may have significant implications for the design of these systems. In this study, Triton-100 (TX) was selected to study its effect on the sorption and desorption of two pesticides (Atrazine and Diuron) from different primary soil size fractions (clay, silt, and sand fractions) under equilibrium sorption and sequential desorption. Soil properties, TX sorption, and pesticide sorption and desorption all exhibited significant particle-size dependence. The cation exchange capacity (CEC) of the bulk soils and the soil fractions determined TX sorption capacity, which in turn determined the desorption efficiency. Desorption of pesticide out of the clay raction is the limiting factor in a surfactant-aided washing system. The solubilization efficiency of the individual surfactant micelles decreased as the amount of surfactant added to the systems increased. Thus, instead of attempting to wash the bulk soil, a better strategy might be to either (1) use only the amount of surfactant that is sufficient to clean the coarse fraction, then separate the fine fraction, and dispose or treat it separately, or (2) to separate the coarse fractions mechanically and then treatthe coarse and fine fractions separately. These results may be applicable to many other hydrophobic organic compounds such as polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) strongly sorbed onto soils and sediments.

  5. Effect of surfactants on the deformation of single droplet in shear flow studied by dissipative particle dynamics

    Science.gov (United States)

    Zhang, Yuzhou; Xu, Junbo; He, Xianfeng

    2018-07-01

    The behaviour of a single droplet in shear flow is a fundamental problem in immiscible liquid-liquid multiphase fluid systems. In this article, the deformation and inclination angle of single droplet covered with surfactants in shear flow at moderate Reynolds number, when both the inertial effects and interfacial tension are the key governing factors, were simulated by dissipative particle dynamics (DPD). Weber number We was adopted to indicate the force state of the droplet and a linear relationship between the deformation parameter D and We was found when Reynolds number Re is about 1-10, which is similar to the relation of D and Capillary number Ca when Re ≪ 1. When the surfactant concentration is lower than the critical micelle concentration (CMC), the distribution of surfactants, the droplet inclination angle θ and the droplet deformation parameter D were investigated at different surfactant density at interface ds and shear rate ?. When the droplet size is close to the characteristic size of surfactant molecules, phase interfaces of water in oil (W/O) and oil in water (O/W) systems have different microstructures, which result in differences in the surfactant distribution, the droplet inclination angle and deformation of the two systems.

  6. Interactions between Surfactants in Solution and Electrospun Protein Fibers: Effects on Release Behavior and Fiber Properties

    DEFF Research Database (Denmark)

    Boutrup Stephansen, Karen; García-Díaz, María; Jessen, Flemming

    2016-01-01

    , and drug delivery. In the present study, we present a systematic investigation of how surfactants and proteins, as physiologically relevant components, interact with insulin-loaded fish sarcoplasmic protein (FSP) electrospun fibers (FSP-Ins fibers) in solution and thereby affect fiber properties...... such as accessible surface hydrophilicity, physical stability, and release characteristics of an encapsulated drug. Interactions between insulin-loaded protein fibers and five anionic surfactants (sodium taurocholate, sodium taurodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium dodecyl sulfate......), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts...

  7. Phospholipid complex enriched micelles: A novel drug delivery approach for promoting the antidiabetic effect of repaglinide.

    Science.gov (United States)

    Kassem, Ahmed Alaa; Abd El-Alim, Sameh Hosam; Basha, Mona; Salama, Abeer

    2017-03-01

    To enhance the oral antidiabetic effect of repaglinide (RG), a newly emerging approach, based on the combination of phospholipid complexation and micelle techniques, was employed. Repaglinide-phospholipid complex (RG-PLC) was prepared by the solvent-evaporation method then characterized using Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and X-ray powder diffraction (XPRD). The results revealed obvious disappearance of the characteristic peaks of the prepared RG-PLCs confirming the formation of drug-phospholipid complex. RG-PLC enriched micelles (RG-PLC-Ms) were prepared by the solvent-evaporation technique employing poloxamer 188 as surfactant. The prepared RG-PLC-Ms showed high drug encapsulation efficiencies (93.81-99.38%), with nanometric particle diameters (500.61-665.32nm) of monodisperse distribution and high stability (Zeta potential < -29.8mV). The in vitro release of RG from RG-PLC-Ms was pH-dependant according to the release media. A higher release pattern was reported in pH=1.2 compared to a more retarded release in pH=6.8 owing to two different kinetics of drug release. Oral antidiabetic effect of two optimized RG-PLC-M formulations was evaluated in an alloxan-induced diabetic rat model for 7-day treatment protocol. The two investigated formulations depicted normal blood glucose, serum malondialdehyde and insulin levels as well as an improved lipid profile, at the end of daily oral treatment, in contrast to RG marketed tablets implying enhanced antidiabetic effect of the drug. Hence, phospholipid-complex enriched micelles approach holds a promising potential for promoting the antidiabetic effect of RG. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Dominant role of wormlike micelles in temperature-responsive viscoelastic properties of their mixtures with polymeric chains

    KAUST Repository

    Molchanov, Vyacheslav S.

    2013-03-01

    Temperature effects on the rheological properties of viscoelastic solutions containing entangled wormlike micelles of potassium oleate and hydrophobically modified polyacrylamide were studied in a wide range of polymer concentrations. A very pronounced drop of viscosity by four orders of magnitude was observed at heating from 20 to 78 °C both in the presence and in the absence of polymer indicating that the wormlike micelles are mainly responsible for this effect. The highly thermosensitive behavior was attributed to the shortening of micellar chains induced by heating. Although the decrease in viscosity is almost the same for both surfactant and surfactant/polymer systems, the absolute values of the viscosity in the presence of polymer are by few orders of magnitude higher, which is due to the formation of a common network of entangled polymer and micellar chains. As a result, the added polymer allows one to get highly temperature responsive system that keeps viscoelastic properties in a much wider range of temperatures, which makes it very promising for various practical applications. © 2012 Elsevier Inc.

  9. Physico-chemical study of new functionalized surfactants having thermo sensitive de-mixing behaviour: use in extraction of uranyl nitrate

    International Nuclear Information System (INIS)

    Prevost, S.

    2006-04-01

    New thermo-sensitive functionalized surfactants with metal-chelating properties have been developed and their physical-chemistry studied. They associate a polyethoxylated nonionic surfactant (CiEj) block and a amino-acid residue as a chelating group. Functionalization preserves both properties of the thermo-sensitive surfactant moiety and the chelating group, a diamide closed to uranyl ionophore.The complexing group participates to the polar head group of the surfactant, increasing the area per molecule. As a result, functionalized surfactants form spherical micelles when diluted in water, and the concentrated part of their phase diagrams exhibits structures having higher curvatures than the nonionic precursor CiEj. The structure of the uranyl - diamide complex has been elucidated by NMR and ESI-MS and is of the type UO 2 (NO 3 ) 2 .L; the associated complexation constant, which is very low, has been evaluated by 1 H NMR.A nitrate salt, LiNO 3 , is added at high concentration to improve complexation. The effect of this salt has been analyzed, and was found to be rather similar to the effect on classical CiEj. When uranyl nitrate complexation occurs, the cloud point decreases dramatically, together with the reduction of the area per head group at micelle/solution interface. This effect can be minimized by using a nonionic precursor having a larger polar head group. The functionalized surfactants have been tested in the cloud point extraction of uranyl nitrate, and have proved their efficiency. Those results demonstrate the viability of the functionalized surfactants design, with a covalent link between a thermo-sensitive surfactant block and a chelating group. (author)

  10. Anionic Surfactant as a Corrosion Inhibitor for Synthesized Ferrous Alloy in Acidic Solution

    Directory of Open Access Journals (Sweden)

    Farida Kellou-Kerkouche

    2013-01-01

    Full Text Available The effect of temperature on the corrosion behaviour of a synthesized iron-based alloy in 1 N sulphuric acid solution has been examined by means of three electrochemical techniques. Thereafter, we studied the influence of an anionic surfactant (sodium dodecyl benzene sulfonate at various concentrations on the electrochemical behaviour of the ferrous alloy. The obtained results show that the temperature increase reduced the performance of the used alloy, in the acidic environment. Otherwise, the surfactant inhibits the alloy dissolution in the sulphuric acid, through its adsorption on the metal surface without modifying the mechanism of corrosion process. We also noticed that the highest inhibition effect is obtained at a concentration above its critical micelle concentration (CMC. Langmuir adsorption isotherm fits well with the experimental data.

  11. Molecular Dynamics Simulations of Adsorption of Poly(acrylic acid) and Poly(methacrylic acid) on Dodecyltrimethylammonium Chloride Micelle in Water: Effect of Charge Density.

    Science.gov (United States)

    Sulatha, Muralidharan S; Natarajan, Upendra

    2015-09-24

    We have investigated the interaction of dodecyltrimethylammonium chloride (DoTA) micelle with weak polyelectrolytes, poly(acrylic acid) and poly(methacrylic acid). Anionic as well as un-ionized forms of the polyelectrolytes were studied. Polyelectrolyte-surfactant complexes were formed within 5-11 ns of the simulation time and were found to be stable. Association is driven purely by electrostatic interactions for anionic chains whereas dispersion interactions also play a dominant role in the case of un-ionized chains. Surfactant headgroup nitrogen atoms are in close contact with the carboxylic oxygens of the polyelectrolyte chain at a distance of 0.35 nm. In the complexes, the polyelectrolyte chains are adsorbed on to the hydrophilic micellar surface and do not penetrate into the hydrophobic core of the micelle. Polyacrylate chain shows higher affinity for complex formation with DoTA as compared to polymethacrylate chain. Anionic polyelectrolyte chains show higher interaction strength as compared to corresponding un-ionized chains. Anionic chains act as polymeric counterion in the complexes, resulting in the displacement of counterions (Na(+) and Cl(-)) into the bulk solution. Anionic chains show distinct shrinkage upon adsorption onto the micelle. Detailed information about the microscopic structure and binding characteristics of these complexes is in agreement with available experimental literature.

  12. SANS study of coated block copolymer micelles

    Czech Academy of Sciences Publication Activity Database

    Pleštil, Josef; Kříž, Jaroslav; Koňák, Čestmír; Pospíšil, Herman; Kadlec, Petr; Sedláková, Zdeňka; Grillo, I.; Cubitt, R.

    2005-01-01

    Roč. 206, č. 12 (2005), s. 1206-1215 ISSN 1022-1352 R&D Projects: GA ČR GA203/03/0600; GA AV ČR IAA1050201; GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z40500505 Keywords : block copolymer micelles * core-shell polymers * nanoparticles Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.111, year: 2005

  13. Thermoresponsive polymer micelles as potential nanosized cancerostatics

    Czech Academy of Sciences Publication Activity Database

    Laga, Richard; Janoušková, Olga; Ulbrich, Karel; Pola, Robert; Blažková, Jana; Filippov, Sergey K.; Etrych, Tomáš; Pechar, Michal

    2015-01-01

    Roč. 16, č. 8 (2015), s. 2493-2505 ISSN 1525-7797 R&D Projects: GA MŠk(CZ) EE2.3.30.0029; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : RAFT polymerization * polymer therapeutics * thermo-responsive micelles Subject RIV: CE - Biochemistry Impact factor: 5.583, year: 2015

  14. Effects of early surfactant treatment persisting for one week after lung transplantation in rats

    NARCIS (Netherlands)

    Erasmus, ME; Hofstede, GJH; Petersen, AH; Haagsman, HP; Oetomo, SB; Prop, J

    We investigated whether pulmonary surfactant in rat lung transplants recovered during the first week post-transplantation, along with symptoms of the reimplantation response, and whether this recovery was affected by early surfactant treatment. The severity of pulmonary injury was varied by

  15. Influence of corona structure on binding of an ionic surfactant in oppositely charged amphiphilic polyelectrolyte micelles

    Czech Academy of Sciences Publication Activity Database

    Delisavva, F.; Uchman, M.; Škvarla, J.; Wozniak, E.; Pavlova, Ewa; Šlouf, Miroslav; Garamus, V. M.; Procházka, K.; Štěpánek, M.

    2016-01-01

    Roč. 32, č. 16 (2016), s. 4059-4065 ISSN 0743-7463 R&D Projects: GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : amphiphilic polymers * polyelectrolyte * corona structure Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.833, year: 2016

  16. Polymeric micelles as a drug carrier for tumor targeting

    Directory of Open Access Journals (Sweden)

    Neha M Dand

    2013-01-01

    Full Text Available Polymeric micelle can be targeted to tumor site by passive and active mechanism. Some inherent properties of polymeric micelle such as size in nanorange, stability in plasma, longevity in vivo, and pathological characteristics of tumor make polymeric micelles to be targeted at the tumor site by passive mechanism called enhanced permeability and retention effect. Polymeric micelle formed from the amphiphilic block copolymer is suitable for encapsulation of poorly water soluble, hydrophobic anticancer drugs. Other characteristics of polymeric micelles such as separated functionality at the outer shell are useful for targeting the anticancer drug to tumor by active mechanisms. Polymeric micelles can be conjugated with many ligands such as antibodies fragments, epidermal growth factors, α2 -glycoprotein, transferrine, and folate to target micelles to cancer cells. Application of heat and ultrasound are the alternative methods to enhance drug accumulation in tumoral cells. Targeting using micelles can also be done to tumor angiogenesis which is the potentially promising target for anticancer drugs. This review summarizes about recently available information regarding targeting the anticancer drug to the tumor site using polymeric micelles.

  17. Diclofenac/biodegradable polymer micelles for ocular applications

    Science.gov (United States)

    Li, Xingyi; Zhang, Zhaoliang; Li, Jie; Sun, Shumao; Weng, Yuhua; Chen, Hao

    2012-07-01

    In this paper, methoxypoly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelle formulations as promising nano-carriers for poorly water soluble drugs were investigated for the delivery of diclofenac to the eye. Diclofenac loaded MPEG-PCL micelles were prepared by a simple solvent-diffusion method and characterized by dynamic light scattering (DLS), atomic force microscopy (AFM), Fourier transform infra-red (FTIR), X-ray diffraction (XRD), differential scanning calorimetery (DSC), etc. With the analysis of XRD and DSC, the diclofenac was present as an amorphous state in the formulation. The in vitro release profile indicated a sustained release manner of diclofenac from the micelles. Meanwhile, in vivo studies on eye irritation were performed with blank MPEG-PCL micelles (200 mg ml-1). The results showed that the developed MPEG-PCL micelles were non-irritants to the eyes of rabbits. In vitro penetration studies across the rabbit cornea demonstrated that the micelle formulations exhibited a 17-fold increase in penetration compared with that of diclofenac phosphate buffered saline (PBS) solution. The in vivo pharmacokinetics profile of the micelle parent drug in the aqueous humor of the rabbit was evaluated and the data showed that the diclofenac loaded MPEG-PCL micelles exhibited a 2-fold increase in AUC0-24 h than that of the diclofenac PBS solution eye drops. These results suggest a great potential of our micelle formulations as a novel ocular drug delivery system to improve the bioavailability of the drugs.

  18. Stereocomplex-Reinforced PEGylated Polylactide Micelle for Optimized Drug Delivery

    Directory of Open Access Journals (Sweden)

    Chunsheng Feng

    2016-04-01

    Full Text Available The instability of PEGylated polylactide micelles is a challenge for drug delivery. Stereocomplex interaction between racemic polylactide chains with different configurations provides an effective strategy to enhance the stability of micelles as the nanocarriers of drugs. In this work, a stereocomplex micelle (SCM self-assembled from the amphiphilic triblock copolymers comprising poly(ethylene glycol (PEG, and dextrorotatory and levorotatory polylactides (PDLA and PLLA was applied for efficient drug delivery. The spherical SCM showed the smallest scale and the lowest critical micelle concentration (CMC than the micelles with single components attributed to the stereocomplex interaction between PDLA and PLLA. 10-Hydroxycamptothecin (HCPT as a model antitumor drug was loaded into micelles. Compared with the loading micelles from individual PDLA and PLLA, the HCPT-loaded SCM exhibited the highest drug loading efficiency (DLE and the slowest drug release in phosphate-buffered saline (PBS at pH 7.4, indicating its enhanced stability in circulation. More fascinatingly, the laden SCM was demonstrated to have the highest cellular uptake of HCPT and suppress malignant cells most effectively in comparison to the HCPT-loaded micelles from single copolymer. In summary, the stereocomplex-enhanced PLA–PEG–PLA micelle may be promising for optimized drug delivery in the clinic.

  19. Biodegradation of surfactant bearing wastes

    International Nuclear Information System (INIS)

    Chitra, S.; Chandran, S.; Sasidhar, P.; Lal, K.B.; Amalraj, R.V.

    1991-01-01

    In nuclear industry, during decontamination of protective wears and contaminated materials, detergents are employed to bring down the level of radioactive contamination within safe limits. However, the surfactant present in these wastes interferes in the chemical treatment process, reducing the decontamination factor. Biodegradation is an efficient and ecologically safe method for surfactant removal. A surfactant degrading culture was isolated and inoculated separately into simulated effluents containing 1% yeast extract and 5-100 ppm sodium lauryl sulphate (SLS) and 1% yeast extract and 5-100 ppm of commercial detergent respectively. The growth of the bacterial culture and the degradation characteristics of the surfactant in the above effluents were monitored under both dynamic and static conditions. (author). 6 refs., 6 figs., 1 tab

  20. Treatment with exogenous surfactant stimulates endogenous surfactant synthesis in premature infants with respiratory distress syndrome

    NARCIS (Netherlands)

    Bunt, JEH; Carnielli, VP; Janssen, DJ; Wattimena, JLD; Hop, WC; Sauer, PJ; Zimmermann, LJI

    2000-01-01

    Objective: Treatment of preterm infants with respiratory distress syndrome (RDS) with exogenous surfactant has greatly improved clinical outcome. Some infants require multiple doses, and it has not been studied whether these large amounts of exogenous surfactant disturb endogenous surfactant

  1. Effect of presence of benzene ring in surfactant hydrophobic chain on the transformation towards one dimensional aggregate

    Directory of Open Access Journals (Sweden)

    Rabah A. Khalil

    2015-07-01

    Full Text Available The formation of wormlike micelle and the following significant changes in rheological properties suffer misunderstanding from both theoretical and fundamental aspects. Recently, we have introduced a theory for interpreting such important phenomenon which is referred to as critical intermolecular forces (CIF. The theory has stated that the hydrophobic effect is the main factor for the formation of worm-like aggregates. Therefore, it seems interesting to check out the validity of this new physical insight through investigating the presence of benzene ring as less hydrophobic group in contrast to that of alkyl in surfactant tail. The mixture of anionic sodium dodecylbenzenesulphonate (SDBS and cationic cetyltrimethylammonium bromide (CTAB shows a high dynamic viscosity peak at the ratio of 80/20 of 3 wt.% CTAB/SDBS indicating the formation of wormlike micelles. The thermodynamic properties have been evaluated for this mixture exhibiting good agreement with the rheological changes. Interestingly, the results show the presence of benzene ring (in SDBS causing a negative effect towards the formation of one dimensional aggregate in contrast to previous results which support the proposed CIF theory. The presence of nonionic surfactant TritonX-100 in binary and ternary systems of SDBS and CTAB prohibits the formation of wormlike micelles.

  2. Surfactant effect on functionalized carbon nanotube coated snowman-like particles and their electro-responsive characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ke; Liu, Ying Dan [Department of Polymer Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Choi, Hyoung Jin, E-mail: hjchoi@inha.ac.kr [Department of Polymer Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of)

    2012-10-15

    The core–shell structured snowman-like (SL) microparticles coated by functionalized multi-walled carbon nanotube (MWNT) were prepared in the presence of different surfactants including cationic surfactant-cetyl trimethylammonium bromide (CTAB) and anionic surfactant-sodium lauryl sulfate (SDS). The effect of surfactants on adsorption onto SL particles was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and conductivity. The cationic surfactant is found to be more effective than anionic surfactant for helping nanotube adsorbed onto microparticle due to the presence of electrostatic interaction between the functionalized MWNT and the surfactant. Furthermore, the MWNT/SL particles dispersed in silicone oil exhibited a typical fibril structure of the electrorheological characteristics under an applied electric field observed by an optical microscope (OM), in which the state of nanotubes wrapped on the particles strongly affects their electro-responsive characteristics.

  3. Surfactant effect on functionalized carbon nanotube coated snowman-like particles and their electro-responsive characteristics

    International Nuclear Information System (INIS)

    Zhang, Ke; Liu, Ying Dan; Choi, Hyoung Jin

    2012-01-01

    The core–shell structured snowman-like (SL) microparticles coated by functionalized multi-walled carbon nanotube (MWNT) were prepared in the presence of different surfactants including cationic surfactant-cetyl trimethylammonium bromide (CTAB) and anionic surfactant-sodium lauryl sulfate (SDS). The effect of surfactants on adsorption onto SL particles was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and conductivity. The cationic surfactant is found to be more effective than anionic surfactant for helping nanotube adsorbed onto microparticle due to the presence of electrostatic interaction between the functionalized MWNT and the surfactant. Furthermore, the MWNT/SL particles dispersed in silicone oil exhibited a typical fibril structure of the electrorheological characteristics under an applied electric field observed by an optical microscope (OM), in which the state of nanotubes wrapped on the particles strongly affects their electro-responsive characteristics.

  4. Role of surfactant on thermoelectric behaviors of organic-inorganic composites

    Science.gov (United States)

    Shin, Sunmi; Roh, Jong Wook; Kim, Hyun-Sik; Chen, Renkun

    2018-05-01

    Hybrid organic/inorganic composites have recently attracted intensive interests as a promising candidate for flexible thermoelectric (TE) devices using inherently soft polymers as well as for increasing the degree of freedom to control TE properties. Experimentally, however, enhanced TE performance in hybrid composites has not been commonly observed, primarily due to inhomogeneous mixing between the inorganic and organic components which leads to limited electrical conduction in the less conductive component and consequently a low power factor in the composites compared to their single-component counterparts. In this study, we investigated the effects of different surfactants on the uniformity of mixing and the TE behaviors of the hybrid composites consisting of Bi0.5Sb1.5Te3 (BST) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). We found that compared to dimethyl sulfoxide, which is the most widely used surfactant, Triton X-100 (TX-100) can lead to homogenous dispersion of BST in PEDOT:PSS. By systematically studying the effects of the surfactant concentration, we can attribute the better mixing capability of TX-100 to its non-ionic property, which results in homogenous mixing with a lower critical micelle concentration. Consequently, we observed simultaneous increase in electrical conductivity and Seebeck coefficient in the BST/PEDOT:PSS composites with the TX-100 surfactant.

  5. Effect of laundry surfactants on surface charge and colloidal stability of silver nanoparticles.

    Science.gov (United States)

    Skoglund, Sara; Lowe, Troy A; Hedberg, Jonas; Blomberg, Eva; Wallinder, Inger Odnevall; Wold, Susanna; Lundin, Maria

    2013-07-16

    The stability of silver nanoparticles (Ag NPs) potentially released from clothing during a laundry cycle and their interactions with laundry-relevant surfactants [anionic (LAS), cationic (DTAC), and nonionic (Berol)] have been investigated. Surface interactions between Ag NPs and surfactants influence their speciation and stability. In the absence of surfactants as well as in the presence of LAS, the negatively charged Ag NPs were stable in solution for more than 1 day. At low DTAC concentrations (≤1 mM), DTAC-Ag NP interactions resulted in charge neutralization and formation of agglomerates. The surface charge of the particles became positive at higher concentrations due to a bilayer type formation of DTAC that prevents from agglomeration due to repulsive electrostatic forces between the positively charged colloids. The adsorption of Berol was enhanced when above its critical micelle concentration (cmc). This resulted in a surface charge close to zero and subsequent agglomeration. Extended DLVO theory calculations were in compliance with observed findings. The stability of the Ag NPs was shown to depend on the charge and concentration of the adsorbed surfactants. Such knowledge is important as it may influence the subsequent transport of Ag NPs through different chemical transients and thus their potential bioavailability and toxicity.

  6. Synthesis and characterization of dialkanolamides from castor oil (Ricinus communis) as nonionic surfactant

    Science.gov (United States)

    Anwar, M.; Wahyuningsih, T. D.

    2017-12-01

    Nonionic surfactant of dialkanolamide derivates was synthesized and characterized from castor oil (Ricinus comunnis). Ricinoleic acid was isolated from castor oil by hydrolysis in alkaline (KOH) condition at 65 °C. Oxidation of ricinoleic acid by dilute potassium permanganate (KMnO4) in alkaline condition at 75-90 °C gave dicarboxylic acid which was then reacted with ethanolamine at 140-160 °C for 6 hours. The product was recrystallized with isopropanol, and the structure elucidation was performed by FTIR, 1HNMR spectrometer, and GC-MS with silylation method. Characterization of surfactants was carried out by surface tension measurement (capillary rise method), Critical Micelle Concentration (CMC) based on turbidity method and calculation of Hydrophilic-Lipophilic Balance (HLB) value with Griffin method and Bancroft rule. The result showed that ricinoleic acid in castor oil is 86.19 % and it is oxidation give an azelaic acid and octanedioic acid in 53.25 %. Amidation of a dicarboxylic acid and ethanolamine at 140-160 °C for 6 hours yielded of N1,N9-bis(2-hydroxyethyl)nona diamide in 49.35 %. Surfactant characterization indicates that dialkanolamide derivates can be used as a surfactant due to its ability to reduce the surface tension of ethanol with CMC at 1.2 g/L, HLB value is 5.58 and can be used as emulsifier water in oil (W/O).

  7. Effect of surfactants on the aggregation of pyronin B and pyronin Y in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Arik, Mustafa; Meral, Kadem [Department of Chemistry, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey); Onganer, Yavuz, E-mail: yonganer@atauni.edu.t [Department of Chemistry, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey)

    2009-06-15

    Molecular dynamics of pyronin B (PyB) and pyronin Y (PyY) in aqueous solution containing different surfactants were investigated by using absorption and fluorescence spectroscopy techniques. First, the interactions of PyB and PyY with the negatively charged surfactant sodium dodecyl sulphate (SDS) were investigated in the below and above critical micelle concentration (cmc). The H-aggregate formation of the dye compounds was observed for below the cmc of SDS surfactant. The absorbance of H-aggregate absorption band of PyB and PyY decreased according to the aggregate-monomer equilibrium by increasing SDS surfactant concentration towards the cmc. Therefore, equilibrium constants of the aggregate formation and oscillator strengths of monomer and aggregate of the dye compounds were calculated from spectral studies. Moreover, aggregate formation dynamics was discussed in terms of thermodynamic functions by using temperature studies. The interactions of PyB and PyY with the positively charged hexadecyltrimethylammonium bromide (CTAB) and neutral Triton X-100 (TX-100) were also studied and it was observed that there was no aggregate formation on the absorption and fluorescence spectra for below and above the cmc.

  8. Optical transition rates of a meso-substituted thiacarbocyanine in methanol-in-oil reverse micelles

    International Nuclear Information System (INIS)

    Oezcelik, Serdar; Zeynep Atay, N.

    2005-01-01

    We report the photophysical properties of 3,3'-diethyl-5,5'-dichloro-9-phenylthiacarbocyanine (DDPT) in methanol-in-oil (m/o) reverse micellar systems which form methanol droplets stabilized with anionic surfactant aerosol-OT (AOT) in n-heptane. The fluorescence quantum yield of DDPT is enhanced by a factor of 17 in the methanol droplet in comparison with bulk methanol. The fluorescence lifetimes of DDPT in m/o reverse micelles are prolonged up to 2.2 ns with increasing molar ratio of methanol to surfactant (w 0 =[MeOH]/[AOT]), whereas the fluorescence lifetime of DDPT in bulk methanol is 75 ps. The non-radiative rate constants of DDPT in the droplets are decreased by a factor of 40, resulting in a remarkable enhancement in quantum yields, indicating that internal motions of DDPT in the droplets are significantly reduced due to strong electrostatic interactions between the positively charged DDPT and the negatively charged sulfonate head-groups of AOT and the spatial confinement induced by the reverse micellar structure

  9. Synthesis of nanosilver particles by reverse micelle method and study of their bactericidal properties

    Energy Technology Data Exchange (ETDEWEB)

    Tran Thi Ngoc Dung; Ngo Quoc Buu; Dang Viet Quang; Le Anh Bang; Nguyen Hoai Chau; Nguyen Thi Ly [Institute of Environmental Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay Distr., Hanoi (Viet Nam); Huynh Thi Ha [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay Distr., Hanoi (Viet Nam); Nguyen Vu Trung [National Institute for Infectious and Tropical Diseases, 1 Ton That Tung, Dong Da Distr., Hanoi (Viet Nam)], E-mail: ttndzung@yahoo.com, E-mail: buu_nq@yahoo.com

    2009-09-01

    Nanosilver particles have been synthesized by the reverse micelle method, where AgNO{sub 3} was used as a silver ions source, NaBH{sub 4} and quercetin - as reducing agents, CTAB, SDOSS and AOT- as surfactants, while the stabilizer was Vietnamese chitosan. Studying the factors influencing the process of nanosilver particle formation, it was shown that the particle size of the nanosilver products depends on the concentration of the reaction components and their stoichiometric ratio. It was also shown that the reaction system using AOT surfactant is capable of producing nanosilver particles with smallest nanoparticles ({phi}{sub av} {approx} 5 nm) and good particle-size distribution. The study on bactericidal activity of the nanosilver products indicated that the disinfecting solution with a nanosilver concentration of 3 ppm was able to inhibit all E.coli and Coliforms, TPC and fungi at 15 ppm, while Vibrio cholerae cells were inactivated completely with 0.5 ppm of nanosilver after 30 minutes exposition.

  10. Biomimicry of surfactant protein C.

    Science.gov (United States)

    Brown, Nathan J; Johansson, Jan; Barron, Annelise E

    2008-10-01

    Since the widespread use of exogenous lung surfactant to treat neonatal respiratory distress syndrome, premature infant survival and respiratory morbidity have dramatically improved. Despite the effectiveness of the animal-derived surfactant preparations, there still remain some concerns and difficulties associated with their use. This has prompted investigation into the creation of synthetic surfactant preparations. However, to date, no clinically used synthetic formulation is as effective as the natural material. This is largely because the previous synthetic formulations lacked analogues of the hydrophobic proteins of the lung surfactant system, SP-B and SP-C, which are critical functional constituents. As a result, recent investigation has turned toward the development of a new generation of synthetic, biomimetic surfactants that contain synthetic phospholipids along with a mimic of the hydrophobic protein portion of lung surfactant. In this Account, we detail our efforts in creating accurate mimics of SP-C for use in a synthetic surfactant replacement therapy. Despite SP-C's seemingly simple structure, the predominantly helical protein is extraordinarily challenging to work with given its extreme hydrophobicity and structural instability, which greatly complicates the creation of an effective SP-C analogue. Drawing inspiration from Nature, two promising biomimetic approaches have led to the creation of rationally designed biopolymers that recapitulate many of SP-C's molecular features. The first approach utilizes detailed SP-C structure-activity relationships and amino acid folding propensities to create a peptide-based analogue, SP-C33. In SP-C33, the problematic and metastable polyvaline helix is replaced with a structurally stable polyleucine helix and includes a well-placed positive charge to prevent aggregation. SP-C33 is structurally stable and eliminates the association propensity of the native protein. The second approach follows the same design

  11. Tensiometric, fluorescence and 1H NMR study of mixed micellization of non-steroidal anti-inflammatory drug sodium salt of ibuprofen in the presence of non-ionic surfactant in aqueous/urea solutions

    International Nuclear Information System (INIS)

    Rub, Malik Abdul; Khan, Farah; Sheikh, Mohmad Shafi; Azum, Naved; Asiri, Abdullah M.

    2016-01-01

    Highlights: • Interaction between (IBF + TX-100) mixtures has been investigated. • (IBF + TX-100) mixtures exhibit synergistic behavior. • Urea increases the surface charge of the micelles resulting halt of the micelles formation. • N agg , K sv and dielectric constant of mixed systems have also been evaluated. • 1 H NMR data suggested that IBF and TX-100 interacts through hydrophobic as well as hydrophillic interaction. - Abstract: The desirable surface/bulk properties for specific applications of drug sodium salt of ibuprofen (IBF) and Triton X-100 (TX-100) can be achieved by adjusting mainly the composition of these systems. The interactions of anionic drug IBF with non-ionic surfactant TX-100 micelles have been investigated using tensiometry, fluorometry and 1 H NMR in aqueous as well in 250 mmol⋅kg −1 urea solutions. Different theoretical models like Clint, Rubingh, and Rosen, etc. were utilized to get information about the nature of interaction between these two in bulk and at the interface. These models disclose that the non-ideal behavior with attractive interaction in bulk and at the interface exists. The steady-state fluorescence quenching study was employed to evaluate micelle aggregation numbers (N agg ), which signify the involvement of surfactant was forever higher compared to IBF. Stern–Volmer binding constants (K sv ), micropolarity (I 1 /I 3 ) and dielectric constant (D exp ) of the mixtures are also obtained using fluorescence method. By the addition of urea raise in the surface charge of the micelles was observed followed by halt of the micellization of drug and surfactant as well as their mixture, therefore cmc values increases followed by decrease in aggregation number. The 1 H NMR resonance intensity variations were paralleled by upfield shifts in the resonance frequencies, due to an increased shielding of IBF happening from closeness of the non-ionic TX-100 surfactant.

  12. Effects of silica-based nanostructures with raspberry-like morphology and surfactant on the interfacial behavior of light, medium, and heavy crude oils at oil-aqueous interfaces

    Science.gov (United States)

    Bai, Lingyun; Li, Chunyan; Korte, Caroline; Huibers, Britta M. J.; Pales, Ashley R.; Liang, Wei-zhen; Ladner, David; Daigle, Hugh; Darnault, Christophe J. G.

    2017-11-01

    Any efficient exploitation of new petroleum reservoirs necessitates developing methods to mobilize the crude oils from such reservoirs. Here silicon dioxide nanoparticles (SiO2 NPs) were used to improve the efficiency of the chemical-enhanced oil recovery process that uses surfactant flooding. Specifically, SiO2 NPs (i.e., 0, 0.001, 0.005, 0.01, 0.05, and 0.1 wt%) and Tween®20, a nonionic surfactant, at 0, 0.5, and 2 critical micelle concentration (CMC) were varied to determine their effect on the stability of nanofluids and the interfacial tension (IFT) at the oil-aqueous interface for 5 wt% brine-surfactant-SiO2 nanofluid-oil systems for West Texas Intermediate light crude oil, Prudhoe Bay medium crude oil, and Lloydminster heavy crude oil. Our study demonstrates that SiO2 NPs may either decrease, increase the IFT of the brine-surfactant-oil systems, or exhibit no effects at all. For the brine-surfactant-oil systems, the constituents of the oil and aqueous substances affected the IFT behavior, with the nanoparticles causing a contrast in IFT trends according to the type of crude oil. For the light oil system (0.5 and 2 CMC Tween®20), the IFT increased as a function of SiO2 NP concentration, while a threshold concentration of SiO2 NPs was observed for the medium (0.5 and 2 CMC Tween®20) and heavy (2 CMC Tween®20) oil systems in terms of IFT trends. Concentrations below the SiO2 NP threshold concentration resulted in a decrease in IFT, and concentrations above this threshold resulted in an increase in IFT. The IFT decreased until the NP concentration reached a threshold concentration where synergetic effects between nonionic surfactants and SiO2 NPs are the opposite and result in antagonistic effects. Adsorption of both SiO2 NPs and surfactants at an interface caused a synergistic effect and an increased reduction in IFT. The effectiveness of the brine-surfactant-SiO2 nanofluids in decreasing the IFT between the oil-aqueous phase for the three tested crude oils

  13. Surfactant flooding of diesel-contaminated soils

    International Nuclear Information System (INIS)

    Peters, R.W.; Montemagno, C.D.; Shem, L.; Lewis, B.A.

    1991-01-01

    At one installation, approximately 60,000 gallons of No. 2 diesel fuel leaked into the subsurface environment, with contamination at depths of 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. The treatability studies focused on four separate phases: (1) leachability studies on the various contaminated soil borings, (2) air stripping studies, (3) bioremediation studies, and (4) surfactant screening/surfactant flooding studies. This paper summarizes the fourth phase of this research program after initial surfactant screening of 21 surfactants. Three of the surfactants were used for the surfactant flooding studies; the results from that phase of the research program are described

  14. Structural investigations of sodium caseinate micelles in complex environments

    Energy Technology Data Exchange (ETDEWEB)

    Huck Iriart, C.; Herrera, M.L.; Candal, R. [Universidad de Buenos Aires, Buenos Aires (Argentina); Oliveira, C.L.P. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil); Torriani, I. [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil)

    2012-07-01

    Full text: The most frequent destabilization mechanisms in Sodium Caseinate (NaCas) emulsions are creaming and flocculation. Coarse or fine emulsions with low protein con- tent destabilize mainly by creaming. If migration mechanism is suppressed, flocculation may become the main mechanism of destabilization. Small Angle X-Ray Scattering (SAXS) technique was applied to investigate sodium caseinate micelles structure in different environments. As many natural products, Sodium Caseinate samples have large polydisperse size distribution. The experimental data was analyzed using advanced modeling approaches. The Form Factor for the Caseinate micelle subunits was described by an ellipsoidal core shell model and the structure factor was split into two contributions, one corresponding to the particle-particle interactions and another one for the long range correlation of the subunits in the supramolecular structure. For the first term the hard sphere structure factor using the Percus-Yevick approximation for closure relation was used and for the second term a fractal model was applied. Three concentrations of sodium Caseinate (2, 5 and 7.5 %wt.) were measured in pure water, sugar solutions (20 %wt.) and in three different lipid phase emulsions containing 10 %wt. sunflower seed, olive and fish oils. Data analysis provided an average casein subunit radius of 4 nm, an average distance between the subunits of around 20nm and a fractal dimension value of around 3 for all samples. As indicated by the values of the correlation lengths for the set of studied samples, the casein aggregation is strongly affected by simple sugar additions and it is enhanced by emulsion droplets hydrophobic interaction. As will be presented, these nanoscale structural results provided by scattering experiments is consistent with macroscopic results obtained from several techniques, providing a new understanding of NaCas emulsions. (author)

  15. Structural investigations of sodium caseinate micelles in complex environments

    International Nuclear Information System (INIS)

    Huck Iriart, C.; Herrera, M.L.; Candal, R.; Oliveira, C.L.P.; Torriani, I.

    2012-01-01

    Full text: The most frequent destabilization mechanisms in Sodium Caseinate (NaCas) emulsions are creaming and flocculation. Coarse or fine emulsions with low protein con- tent destabilize mainly by creaming. If migration mechanism is suppressed, flocculation may become the main mechanism of destabilization. Small Angle X-Ray Scattering (SAXS) technique was applied to investigate sodium caseinate micelles structure in different environments. As many natural products, Sodium Caseinate samples have large polydisperse size distribution. The experimental data was analyzed using advanced modeling approaches. The Form Factor for the Caseinate micelle subunits was described by an ellipsoidal core shell model and the structure factor was split into two contributions, one corresponding to the particle-particle interactions and another one for the long range correlation of the subunits in the supramolecular structure. For the first term the hard sphere structure factor using the Percus-Yevick approximation for closure relation was used and for the second term a fractal model was applied. Three concentrations of sodium Caseinate (2, 5 and 7.5 %wt.) were measured in pure water, sugar solutions (20 %wt.) and in three different lipid phase emulsions containing 10 %wt. sunflower seed, olive and fish oils. Data analysis provided an average casein subunit radius of 4 nm, an average distance between the subunits of around 20nm and a fractal dimension value of around 3 for all samples. As indicated by the values of the correlation lengths for the set of studied samples, the casein aggregation is strongly affected by simple sugar additions and it is enhanced by emulsion droplets hydrophobic interaction. As will be presented, these nanoscale structural results provided by scattering experiments is consistent with macroscopic results obtained from several techniques, providing a new understanding of NaCas emulsions. (author)

  16. Lactoferrin binding to transglutaminase cross-linked casein micelles

    NARCIS (Netherlands)

    Anema, S.G.; de Kruif, C.G.|info:eu-repo/dai/nl/073609609

    2012-01-01

    Casein micelles in skim milk were either untreated (untreated milk) or were cross-linked using transglutaminase (TGA-milk). Added lactoferrin (LF) bound to the casein micelles and followed Langmuir adsorption isotherms. The adsorption level was the same in both milks and decreased the micellar zeta

  17. Structure and Stability of Complex Coacervate Core Micelles with Lysozyme

    NARCIS (Netherlands)

    Lindhoud, Saskia; de Vries, Renko; Norde, Willem; Cohen Stuart, Martinus Abraham

    2007-01-01

    Encapsulation of enzymes by polymers is a promising method to influence their activity and stability. Here, we explore the use of complex coacervate core micelles for encapsulation of enzymes. The core of the micelles consists of negatively charged blocks of the diblock copolymer PAA42PAAm417 and

  18. Structure and stability of complex coacervate core micelles with lysozyme

    NARCIS (Netherlands)

    Lindhoud, Saskia; de Vries, Renko; Norde, Willem; Cohen Stuart, Martien A.

    Encapsulation of enzymes by polymers is a promising method to influence their activity and stability. Here, we explore the use of complex coacervate core micelles for encapsulation of enzymes. The core of the micelles consists of negatively charged blocks of the diblock copolymer PAA(42)PAAm(417)

  19. Stimuli-responsive biodegradable polymeric micelles for targeted cancer therapy

    NARCIS (Netherlands)

    Talelli, M.A.

    2011-01-01

    Thermosensitive and biodegradable polymeric micelles based on mPEG-b-pHPMAmLacn have shown very promising results during the past years. The results presented in this thesis illustrate the high potential of these micelles for anticancer therapy and imaging and fully justify further pharmaceutical

  20. Characterization of Phospholipid Mixed Micelles by Translational Diffusion

    International Nuclear Information System (INIS)

    Chou, James J.; Baber, James L.; Bax, Ad

    2004-01-01

    The concentration dependence of the translational self diffusion rate, D s , has been measured for a range of micelle and mixed micelle systems. Use of bipolar gradient pulse pairs in the longitudinal eddy current delay experiment minimizes NOE attenuation and is found critical for optimizing sensitivity of the translational diffusion measurement of macromolecules and aggregates. For low volume fractions Φ (Φ ≤ 15% v/v) of the micelles, experimental measurement of the concentration dependence, combined with use of the D s =D o (1-3.2λΦ) relationship, yields the hydrodynamic volume. For proteins, the hydrodynamic volume, derived from D s at infinitely dilute concentration, is found to be about 2.6 times the unhydrated molecular volume. Using the data collected for hen egg white lysozyme as a reference, diffusion data for dihexanoyl phosphatidylcholine (DHPC) micelles indicate approximately 27 molecules per micelle, and a critical micelle concentration of 14 mM. Differences in translational diffusion rates for detergent and long chain phospholipids in mixed micelles are attributed to rapid exchange between free and micelle-bound detergent. This difference permits determination of the free detergent concentration, which, for a high detergent to long chain phospholipid molar ratio, is found to depend strongly on this ratio. The hydrodynamic volume of DHPC/POPC bicelles, loaded with an M2 channel peptide homolog, derived from translational diffusion, predicts a rotational correlation time that slightly exceeds the value obtained from peptide 15 N relaxation data

  1. The thermal signature of wormlike micelles

    International Nuclear Information System (INIS)

    Ito, Thiago Heiji; Clinckspoor, Karl Jan; Nunes de Souza, Renato; Sabadini, Edvaldo

    2016-01-01

    Highlights: • Giant micelle formation has a characteristic exothermic profile, for these systems. • The enthalpy of formation is dependent on the planarity of the co-solute. • The affinity is dependent on the enthalpy and critical concentration of the species. • The higher the affinity, the higher thermal stability and size of the micelles. - Abstract: The variations in enthalpy (Δ f H WLM ) and critical concentrations associated with the formation of wormlike micelles (WLMs) from combinations of tetradecyltrimethylammonium bromide (C 14 TAB) and various aromatic co-solutes were determined using isothermal titration calorimetry (ITC). Three groups of aromatic molecules were investigated: neutral (phenol), benzoate derivatives and cinnamate derivatives. In addition, the thermal stabilities of the WLMs (of hexadecyltrimethylammonium bromide, C 16 TAB) and the aromatic co-solutes of the three groups were investigated by measuring the temperatures at which the WLMs break and lose their ability to produce hydrodynamic drag reduction. A comparison of the results was used to establish correlations between the spontaneity of WLMs formation, their thermal stability and the molecular structure of the aromatic co-solutes. A characteristic thermal pattern with four steps was observed when WLMs are formed, that depended on the co-solute structure. Micellar growth was found to be an exothermic process, related to the fusion of the end caps allied with the incorporation of more co-solutes. The co-solutes that had negative charge and were able to maintain planar configuration demonstrated stronger interactions and also showed higher thermal stability through drag reduction.

  2. pH dependent polymeric micelle adsorption

    Energy Technology Data Exchange (ETDEWEB)

    McLean, S C; Gee, M L [The University of Melbourne, VIC (Australia). School of Chemistry

    2003-07-01

    Full text: Poly(2-vinylpyridine)-poly(ethylene oxide) (P2VP-PEO) shows potential as a possible drug delivery system for anti-tumour drugs since it forms pH dependent polymeric micelles. Hence to better understand the adsorption behaviour of this polymer we have studied the interaction forces between layers of P2VP-PEO adsorbed onto silica as a function of solution pH using an Atomic Force Microscope (AFM). When P2VP-PEO is initially adsorbed above the pKa of the P2VP block, P2VP-PEO adsorbs from solution as micelles that exist as either partially collapsed- or a hemi-micelles at the silica surface. Below the pKa of P2VP, the P2VP-PEO adsorbs as unimers, forming a compact layer with little looping and tailing into solution. When initial adsorption of P2VP-PEO is in the form of unimers, any driving force to self-assembly of the now charge neutral polymer is kinetically hindered. Hence, after initial adsorption at pH 3.6, a subsequent increase in pH to 6.6 results in a slow surface restructuring towards self-assembly and equilibrium. When the pH is increased from pH 6.6 to 9.7 there is a continuation of the evolution of the system to its equilibrium position during which the adsorbed P2VP-PEO unimers continue to 'unravel' from the surface, extending away from it, towards eventual complete surface self-assembly.

  3. A fluorescent molecular sensor for pH windows in traditional and polymeric biocompatible micelles: comicellization of anionic species to shift and reshape the ON window.

    Science.gov (United States)

    Cavallaro, Gennara; Giammona, Gaetano; Pasotti, Luca; Pallavicini, Piersandro

    2011-09-12

    A new approach is presented to obtain fluorescent sensors for pH windows that work in water and under biomimetic conditions. A single molecule that features all-covalently linked components is used, thus making it capable of working as a fluorescent sensor with an OFF/ON/OFF response to pH value. The components are a tertiary amine, a pyridine, and a fluorophore (pyrene). The forms with both protonated bases or both neutral bases quench the pyrene fluorescence, whereas the form with the neutral pyridine and protonated amine groups is fluorescent. The molecular sensor is also equipped with a long alkyl chain to make it highly hydrophobic in all its protonated and unprotonated forms, that is, either when neutral or charged. Accordingly, it can be confined at any pH value either in traditional (i.e., low-molecular-weight) nonionic surfactant micelles or inside polymeric, biocompatible micellar containers. Relevant for future applications in vivo, thanks to its strong hydrophobicity, no leakage of the molecular sensor is observed from the polymeric biocompatible micelles. Due to the proximity of the pyridine and amine functions in the molecular structure and the poor hydration inside the micelles, the observed pK(a) values are low so that the ON window is positioned at very low pH values. However, the window can be shifted to biologically relevant values by comicellization of anionic species. In particular, in the micelles of the nonionic surfactant TritonX-100, a shift of the ON window to pH 4-6 is obtained by addition of the anionic sodium dodecyl sulphate surfactant, whose negative charge promotes the stability of the protonated forms of the pyridine and amine fragments. In the case of the polymeric micelles, we introduce the use of the amphiphilic polystyrene sulfonate anionic polyelectrolyte, the comicellization of which induces a shift and sharpening of the ON window that is centered at pH 4. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Low-Dimensional Nanoparticle Clustering in Polymer Micelles and Their Transverse Relaxivity Rates

    Science.gov (United States)

    Hickey, Robert J.; Meng, Xin; Zhang, Peijun; Park, So-Jung

    2015-01-01

    One- or two-dimensional arrays of iron oxide nanoparticles were formed in colloidal assemblies of amphiphilic polymers. Electron tomography imaging revealed that nanoparticles are arranged into one-dimensional strings in magneto-micelles or two-dimensional sheets in magneto-core/shell assemblies. The distinct directional assembly behavior was attributed to the interparticle interaction relative to the nanoparticle–polymer interaction, which was modulated by varying the cosolvent used for the solution phase self-assembly. Magneto-core/shell assemblies with varying structural parameters were formed with a range of different sized as-synthesized nanoparticles. The transverse magnetic relaxivity rates (r2) of a series of different assemblies were determined to examine the effect of nanoparticle arrangement on the magnetic relaxivity for their potential applications in MRI. The results indicated that the assembly structure of nanoparticles in polymer micelles significantly affects the r2 of surrounding water, providing a way to control magnetic relaxivity. PMID:23731021

  5. Effect of sodium azide addition and aging storage on casein micelle size

    Science.gov (United States)

    Sinaga, H.; Deeth, H.; Bhandari, B.

    2018-02-01

    Casein micelles affected most of milk properties, therefore the use sodium azide as milk preservation is not expected to alter milk properties during storage, including the casein micelle size. The aim of this study was to analyse casein micelle size after the addition of sodium azide during storage. The experiment was performed as a complete block randomised design with three replications. The addition of 0.02-0.10% Na-azide do not lead to any noticeable differences in average casein size at the same day and show similar trend after 14 day-storage. At concentration of 0.02% sodium azide (Na-azide), the size of pasteurised milk did not change up to 12 days, while the size of raw skim milk slightly increased by ageing time at day 5. The treated concentration did not affect the size distribution, except for milk with 0.02% Na-azide which had narrower distribution compared to other treated and control milk. The finding from this study suggests that the role of Na-azide in this experiments during storage at 4°C is only for preventing the microbial growth.

  6. Formation and characterization of zein-propylene glycol alginate-surfactant ternary complexes: Effect of surfactant type.

    Science.gov (United States)

    Dai, Lei; Sun, Cuixia; Wei, Yang; Zhan, Xinyu; Mao, Like; Gao, Yanxiang

    2018-08-30

    In this study, zein, propylene glycol alginate (PGA) and surfactant ternary complexes were fabricated by antisolvent co-precipitation method. Two types of surfactants (rhamnolipid and lecithin) were applied to generate zein-PGA-rhamnolipid (Z-P-R) and zein-PGA-lecithin (Z-P-L) ternary complexes, respectively. Results showed that the surfactant types significantly affected the properties of ternary complexes. The formation of ternary complexes was mainly due to the non-covalent interactions such as hydrogen bonding, electrostatic interaction and hydrophobic interactions among zein, PGA and surfactants. Moreover, the thermal stability of ternary complexes was enhanced with increasing the levels of both surfactants. Notably, ternary complex dispersions exhibited better stability against pH from 2 to 8. Furthermore, a compact network structure was observed in Z-P-R ternary complex, while Z-P-L ternary complex remained the spherical structure. These findings would provide new insights into the development of novel delivery system and expand the options, when zein-based complexes were utilized under different environment conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Effect of solvent and temperature on the size distribution of casein micelles measured by dynamic light scattering.

    Science.gov (United States)

    Beliciu, C M; Moraru, C I

    2009-05-01

    The objectives of this study were to investigate the effect of the solvent on the accuracy of casein micelle particle size determination by dynamic light scattering (DLS) at different temperatures and to establish a clear protocol for these measurements. Dynamic light scattering analyses were performed at 6, 20, and 50 degrees C using a 90Plus Nanoparticle Size Analyzer (Brookhaven Instruments, Holtsville, NY). Raw and pasteurized skim milk were used as sources of casein micelles. Simulated milk ultrafiltrate, ultrafiltered water, and permeate obtained by ultrafiltration of skim milk using a 10-kDa cutoff membrane were used as solvents. The pH, ionic concentration, refractive index, and viscosity of all solvents were determined. The solvents were evaluated by DLS to ensure that they did not have a significant influence on the results of the particle size measurements. Experimental protocols were developed for accurate measurement of particle sizes in all solvents and experimental conditions. All measurements had good reproducibility, with coefficients of variation below 5%. Both the solvent and the temperature had a significant effect on the measured effective diameter of the casein micelles. When ultrafiltered permeate was used as a solvent, the particle size and polydispersity of casein micelles decreased as temperature increased. The effective diameter of casein micelles from raw skim milk diluted with ultrafiltered permeate was 176.4 +/- 5.3 nm at 6 degrees C, 177.4 +/- 1.9 nm at 20 degrees C, and 137.3 +/- 2.7 nm at 50 degrees C. This trend was justified by the increased strength of hydrophobic bonds with increasing temperature. Overall, the results of this study suggest that the most suitable solvent for the DLS analyses of casein micelles was casein-depleted ultrafiltered permeate. Dilution with water led to micelle dissociation, which significantly affected the DLS measurements, especially at 6 and 20 degrees C. Simulated milk ultrafiltrate seemed to give

  8. Desorption of organophosphorous pesticides from soil with wastewater and surfactant solutions

    International Nuclear Information System (INIS)

    Hernandez-Soriano, M. C.; Mingorance, M. D.; Pena, A.

    2009-01-01

    Surfactants can be introduced in the environment by wastewater discharge, point-charge pollution or deliberate action, e. g. to remediate contaminated soil or groundwater. The irrigation of soil with wastewater containing surfactants may modify pesticide desorption from soil, thus affecting their affecting their environmental fate. Desorption from soil of the plain of Granada (South-eastern Spain) of two organophosphorous pesticides, diazinon and dimethoate, differing in solubility and hydrophobicity, has been evaluated in the presence of different surfactant aqueous solutions and municipal wastewater. (Author)

  9. Synthesis of carbohydrate-based surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Pemberton, Jeanne E.; Polt, Robin L.; Maier, Raina M.

    2016-11-22

    The present invention provides carbohydrate-based surfactants and methods for producing the same. Methods for producing carbohydrate-based surfactants include using a glycosylation promoter to link a carbohydrate or its derivative to a hydrophobic compound.

  10. Casein maps: Effect of ethanol, pH, temperature, and CaCl2 on the particle size of reconstituted casein micelles

    Science.gov (United States)

    Ye, Ran; Harte, Federico

    2015-01-01

    Although conditions favoring casein micelle aggregation are well known, factors promoting the dissociation of the casein micelle are not fully understood. It was our objective to investigate the ethanol-induced dissociation of micellar casein as affected by temperature and a wide range of pH, along with the concentrations of calcium and casein. Two different concentrations of casein micelles were dispersed in imidazole buffer with 0 to 80% ethanol (vol/vol) and 2 and 10 mM calcium. Apparent micelle size was determined by dynamic light scattering at 5, 30, and 60°C. In the absence of ethanol, casein precipitation occurred at pH 4.6 in imidazole buffer. Ten to forty percent ethanol promoted casein aggregation (>1,000 nm) and higher temperature (30 and 60°C) enhanced this effect. Higher ethanol concentrations at 50 to 80% induced the dissociation (casein micelle upon acidification (pH 8) in imidazole buffer. In addition, higher concentrations of casein (0.25 mg/mL) and calcium (20 mM) caused the formation of larger aggregates (>1,000 nm) in the presence of ethanol when comparing with the initial lower concentrations of casein (0.1 mg/mL) and calcium (2 mM). Casein micelle dissociation can be achieved near the isoelectric pH by modifying the solvent composition and temperature. PMID:23200467

  11. Neonatal varicella pneumonia, surfactant replacement therapy

    Directory of Open Access Journals (Sweden)

    Mousa Ahmadpour-kacho

    2015-12-01

    Full Text Available Background: Chickenpox is a very contagious viral disease that caused by varicella-zoster virus, which appears in the first week of life secondary to transplacental transmission of infection from the affected mother. When mother catches the disease five days before and up to two days after the delivery, the chance of varicella in neonate in first week of life is 17%. A generalized papulovesicular lesion is the most common clinical feature. Respiratory involvement may lead to giant cell pneumonia and respiratory failure. The mortality rate is up to 30% in the case of no treatment, often due to pneumonia. Treatment includes hospitalization, isolation and administration of intravenous acyclovir. The aim of this case report is to introduce the exogenous surfactant replacement therapy after intubation and mechanical ventilation for respiratory failure in neonatal chickenpox pneumonia and respiratory distress. Case Presentation: A seven-day-old neonate boy was admitted to the Neonatal Intensive Care Unit at Amirkola Children’s Hospital, Babol, north of Iran, with generalized papulovesicular lesions and respiratory distress. His mother has had a history of Varicella 4 days before delivery. He was isolated and given supportive care, intravenous acyclovir and antibiotics. On the second day, he was intubated and connected to mechanical ventilator due to severe pneumonia and respiratory failure. Because of sever pulmonary involvement evidenced by Chest X-Ray and high ventilators set-up requirement, intratracheal surfactant was administered in two doses separated by 12 hours. He was discharged after 14 days without any complication with good general condition. Conclusion: Exogenous surfactant replacement therapy can be useful as an adjunctive therapy for the treatment of respiratory failure due to neonatal chickenpox.

  12. Binding of cationic surfactants to humic substances

    NARCIS (Netherlands)

    Ishiguro, M.; Tan, W.; Koopal, L.K.

    2007-01-01

    Commercial surfactants are introduced into the environment either through waste products or site-specific contamination. The amphiphilic nature of both surfactants and humic substances (HS) leads to their mutual attraction especially when surfactant and HS are oppositely charged. Binding of the

  13. Synthesis and characterization of erbium-doped SiO2 nanoparticles fabricated by using reverse micelle and sol-gel processing

    International Nuclear Information System (INIS)

    Park, Hoyyul; Bae, Dongsik

    2012-01-01

    Erbium-doped SiO 2 nanoparticles have been synthesized using a reverse micelle technique combined with metal-alkoxide hydrolysis and condensation. The sizes and the morphologies of the erbium-doped SiO 2 nanoparticles could be changed by varying the molar ratio of water to surfactant. The sizes and the morphologies of the erbium-doped SiO 2 nanoparticles were examined by using a transmission electron microscope. The average size of synthesized erbium-doped SiO 2 nanoparticles was approximately 20 - 25 nm and that of the erbium particles was 3 - 5 nm. The effects of the synthesis parameters, such as the molar ratio of water to surfactant, are discussed.

  14. Enhanced solubility and targeted delivery of curcumin by lipopeptide micelles.

    Science.gov (United States)

    Liang, Ju; Wu, Wenlan; Lai, Danyu; Li, Junbo; Fang, Cailin

    2015-01-01

    A lipopeptide (LP)-containing KKGRGDS as the hydrophilic heads and lauric acid (C12) as the hydrophobic tails has been designed and prepared by standard solid-phase peptide synthesis technique. LP can self-assemble into spherical micelles with the size of ~30 nm in PBS (phosphate buffer saline) (pH 7.4). Curcumin-loaded LP micelles were prepared in order to increase the water solubility, sustain the releasing rate, and improve the tumor targeted delivery of curcumin. Water solubility, cytotoxicity, in vitro release behavior, and intracellular uptake of curcumin-loaded LP micelles were investigated. The results showed that LP micelles can increase the water solubility of curcumin 1.1 × 10(3) times and sustain the release of curcumin in a low rate. Curcumin-loaded LP micelles showed much higher cell inhibition than free curcumin on human cervix carcinoma (HeLa) and HepG2 cells. When incubating these curcumin-loaded micelles with HeLa and COS7 cells, due to the over-expression of integrins on cancer cells, the micelles can efficiently use the tumor-targeting function of RGD (functionalized peptide sequences: Arg-Gly-Asp) sequence to deliver the drug into HeLa cells, and better efficiency of the self-assembled LP micelles for curcumin delivery than crude curcumin was also confirmed by LCSM (laser confocal scanning microscope) assays. Combined with the enhanced solubility and higher cell inhibition, LP micelles reported in this study may be promising in clinical application for targeted curcumin delivery.

  15. Stereocomplex micelle from nonlinear enantiomeric copolymers efficiently transports antineoplastic drug

    Science.gov (United States)

    Wang, Jixue; Shen, Kexin; Xu, Weiguo; Ding, Jianxun; Wang, Xiaoqing; Liu, Tongjun; Wang, Chunxi; Chen, Xuesi

    2015-05-01

    Nanoscale polymeric micelles have attracted more and more attention as a promising nanocarrier for controlled delivery of antineoplastic drugs. Herein, the doxorubicin (DOX)-loaded poly(D-lactide)-based micelle (PDM/DOX), poly(L-lactide)-based micelle (PLM/DOX), and stereocomplex micelle (SCM/DOX) from the equimolar mixture of the enantiomeric four-armed poly(ethylene glycol)-polylactide (PEG-PLA) copolymers were successfully fabricated. In phosphate-buffered saline (PBS) at pH 7.4, SCM/DOX exhibited the smallest hydrodynamic diameter ( D h) of 90 ± 4.2 nm and the slowest DOX release compared with PDM/DOX and PLM/DOX. Moreover, PDM/DOX, PLM/DOX, and SCM/DOX exhibited almost stable D hs of around 115, 105, and 90 nm at above normal physiological condition, respectively, which endowed them with great potential in controlled drug delivery. The intracellular DOX fluorescence intensity after the incubation with the laden micelles was different degrees weaker than that incubated with free DOX · HCl within 12 h, probably due to the slow DOX release from micelles. As the incubation time reached to 24 h, all the cells incubated with the laden micelles, especially SCM/DOX, demonstrated a stronger intracellular DOX fluorescence intensity than free DOX · HCl-cultured ones. More importantly, all the DOX-loaded micelles, especially SCM/DOX, exhibited potent antineoplastic efficacy in vitro, excellent serum albumin-tolerance stability, and satisfactory hemocompatibility. These encouraging data indicated that the loading micelles from nonlinear enantiomeric copolymers, especially SCM/DOX, might be promising in clinical systemic chemotherapy through intravenous injection.

  16. Nonionic Fluorinated Surfactant Removal from Mesoporous Film Using sc-CO2.

    Science.gov (United States)

    Chavez Panduro, Elvia A; Assaker, Karine; Beuvier, Thomas; Blin, Jean-Luc; Stébé, Marie-José; Konovalov, Oleg; Gibaud, Alain

    2017-01-25

    Surfactant templated silica thin films were self-assembled on solid substrates by dip-coating using a partially fluorinated surfactant R 8 F (EO) 9 as the liquid crystal template. The aim was 2-fold: first we checked which composition in the phase diagram was corresponding to a 2D rectangular highly ordered crystalline phase and second we exposed the films to sc-CO 2 to foster the removal of the surfactant. The films were characterized by in situ X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS) under CO 2 pressure from 0 to 100 bar at 34 °C. GISAXS patterns reveal the formation of a 2-D rectangular structure at a molar ratio R 8 F (EO) 9 /Si equal to 0.1. R 8 F (EO) 9 micelles have a cylindrical shape, which have a core/shell structure ordered in a hexagonal system. The core contains the R 8 F part and the shell is a mixture of (EO) 9 embedded in the silica matrix. We further evidence that the extraction of the template using supercritical carbon dioxide can be successfully achieved. This can be attributed to both the low solubility parameter of the surfactants and the fluorine and ethylene oxide CO 2 -philic groups. The initial 2D rectangular structure was well preserved after depressurization of the cell and removal of the surfactant. We attribute the very high stability of the rinsed film to the large value of the wall thickness relatively to the small pore size.

  17. Persurf, a new method to improve surfactant delivery: a study in surfactant depleted rats.

    Directory of Open Access Journals (Sweden)

    Wolfram Burkhardt

    Full Text Available PURPOSE: Exogenous surfactant is not very effective in adults with ARDS, since surfactant does not reach atelectatic alveoli. Perfluorocarbons (PFC can recruit atelectatic areas but do not replace impaired endogenous surfactant. A surfactant-PFC-mixture could combine benefits of both therapies. The aim of the proof-of-principal-study was to produce a PFC-in-surfactant emulsion (Persurf and to test in surfactant depleted Wistar rats whether Persurf achieves I. a more homogenous pulmonary distribution and II. a more homogenous recruitment of alveoli when compared with surfactant or PFC alone. METHODS: Three different PFC were mixed with surfactant and phospholipid concentration in the emulsion was measured. After surfactant depletion, animals either received 30 ml/kg of PF5080, 100 mg/kg of stained (green dye Curosurf™ or 30 ml/kg of Persurf. Lungs were fixated after 1 hour of ventilation and alveolar aeration and surfactant distribution was estimated by a stereological approach. RESULTS: Persurf contained 3 mg/ml phospholipids and was stable for more than 48 hours. Persurf-administration improved oxygenation. Histological evaluation revealed a more homogenous surfactant distribution and alveolar inflation when compared with surfactant treated animals. CONCLUSIONS: In surfactant depleted rats administration of PFC-in-surfactant emulsion leads to a more homogenous distribution and aeration of the lung than surfactant alone.

  18. Reverse micelles as a tool for probing solvent modulation of protein dynamics: Reverse micelle encapsulated hemoglobin

    Science.gov (United States)

    Roche, Camille J.; Dantsker, David; Heller, Elizabeth R.; Sabat, Joseph E.; Friedman, Joel M.

    2013-08-01

    Hydration waters impact protein dynamics. Dissecting the interplay between hydration waters and dynamics requires a protein that manifests a broad range of dynamics. Proteins in reverse micelles (RMs) have promise as tools to achieve this objective because the water content can be manipulated. Hemoglobin is an appropriate tool with which to probe hydration effects. We describe both a protocol for hemoglobin encapsulation in reverse micelles and a facile method using PEG and cosolvents to manipulate water content. Hydration properties are probed using the water-sensitive fluorescence from Hb bound pyranine and covalently attached Badan. Protein dynamics are probed through ligand recombination traces derived from photodissociated carbonmonoxy hemoglobin on a log scale that exposes the potential role of both α and β solvent fluctuations in modulating protein dynamics. The results open the possibility of probing hydration level phenomena in this system using a combination of NMR and optical probes.

  19. The impact of alkyl sulfate surfactant geometry and electrolyte on the co-adsorption of anionic surfactants with model perfumes at the air-solution interface.

    Science.gov (United States)

    Bradbury, Robert; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Jones, Craig

    2013-08-01

    The impact of surfactant geometry and electrolyte on the co-adsorption of anionic surfactants and model perfumes at the air-solution interface has been studied by neutron reflectivity. The more hydrophobic perfume linalool, competes more favourably for the surface with sodium dodecylsulfate than was previously reported for the anionic surfactant, sodium dodecyl 6-benzenesulfonate. Due to an increase in surface activity of the sodium dodecylsulfate, the addition of electrolyte results in a reduction in the linalool adsorption. Changing the alkyl chain length affects the relative adsorption of linalool and surfactant at the interface. Similar measurements for the different alkyl sulfates and with electrolyte with the more hydrophilic perfume phenyl ethanol, reveal broadly similar trends. Although the relative adsorption of phenyl ethanol with sodium dodecylsulfate is substantially enhanced compared to sodium dodecyl-6-benzenesulfonate the effects are not as significant as was observed with linalool. The variations with alkyl chain geometry show the importance of the hydrophobic interaction between the perfume and surfactant and changes in the packing constraints on the relative adsorption. The results highlight the importance of the specific interaction between the surfactant and perfume, and the surfactant and perfume geometries on the relative adsorption at the interface. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Reactive surfactants in heterophase polymerization

    NARCIS (Netherlands)

    Guyot, A.; Tauer, K.; Asua, J.M.; Es, van J.J.G.S.; Gauthier, C.; Hellgren, A.C.; Sherrington, D.C.; Montoya-Goni, A.; Sjöberg, M.; Sindt, O.; Vidal, F.F.M.; Unzue, M.; Schoonbrood, H.A.S.; Schipper, E.T.W.M.; Lacroix-Desmazes, P.

    1999-01-01

    This paper summarizes the work carried out during 3 years in a Network of the program "Human Capital and Mobility" of the European Union CHRX 93-0159 entitled "Reactive surfactants in heterophase polymerization for high performance polymers". A series of about 25 original papers will be published in

  1. Self-assembly of micelles into designed networks

    Directory of Open Access Journals (Sweden)

    Pyatenko Alexander

    2007-01-01

    Full Text Available AbstractThe EO20PO70EO20(molecular weight 5800 amphiphile as a template is to form dispersed micelle structures. Silver nanoparticles, as inorganic precursors synthesized by a laser ablation method in pure water, are able to produce the highly ordered vesicles detected by TEM micrography. The thickness of the outer layer of a micelle, formed by the silver nanoparticles interacting preferentially with the more hydrophilic EO20block, was around 3.5 nm. The vesicular structure ensembled from micelles is due to proceeding to the mixture of cubic and hexagonal phases.

  2. Depletion interaction of casein micelles and an exocellular polysaccharide

    Science.gov (United States)

    Tuinier, R.; Ten Grotenhuis, E.; Holt, C.; Timmins, P. A.; de Kruif, C. G.

    1999-07-01

    Casein micelles become mutually attractive when an exocellular polysaccharide produced by Lactococcus lactis subsp. cremoris NIZO B40 (hereafter called EPS) is added to skim milk. The attraction can be explained as a depletion interaction between the casein micelles induced by the nonadsorbing EPS. We used three scattering techniques (small-angle neutron scattering, turbidity measurements, and dynamic light scattering) to measure the attraction. In order to connect the theory of depletion interaction with experiment, we calculated structure factors of hard spheres interacting by a depletion pair potential. Theoretical predictions and all the experiments showed that casein micelles became more attractive upon increasing the EPS concentration.

  3. Multi-technique approach on the interaction between sugar-based surfactant n-dodecyl β-D-maltoside and bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Mohd Sajid, E-mail: smsajidali@gmail.com; Al-Lohedan, Hamad A.

    2016-01-15

    A multi-technique approach which comprises various basic and advanced techniques, such as surface tensiometry, synchronous, intrinsic and extrinsic fluorescence, far and near-UV circular dichroism (CD), dynamic light scattering (DLS), Fourier transform infra-red (FTIR) and UV–visible spectrophotometries was applied to understand the interaction between biocompatible sugar-based surfactant n-dodecyl β-D-maltoside (C{sub 12}G{sub 2}) and bovine serum albumin (BSA). Formation of complex between surfactant and protein was initially confirmed by surface tension and UV absorption spectroscopy. The presence of BSA shifted the critical micelle concentration of the surfactant at higher concentration and in a similar way the UV spectrum of the BSA was altered by addition of small amount of surfactant. The interfacial properties of the complex such as π{sub cmc} (the surface pressure at the cmc), Γ{sub max} (the maximum surface excess) and A{sub min} (the minimum surface area per molecule) were also calculated. Addition of surfactant causes the quenching of BSA fluorescence and a large blue-shift at both excitation wavelengths (280 and 295 nm) owing to the hydrophobic interaction between surfactant and protein. The quenching took place via static mechanism. Extrinsic fluorescence of 1-anilino-8-naphthalene sulfonate (ANS) increased as a result of the unfolding of the protein. The secondary and tertiary structure of BSA also influenced as revealed by the collective information obtained by far-UV CD, near-UV CD and FTIR spectroscopies. The increase in the size of the complex as a results of the partial unfolding was also confirmed by DLS measurements as well as resonance Rayleigh scattering (RRS). - Highlights: • In the presence of BSA cmc of sugar surfactant n-dodecyl β-D-maltoside increased due to the binding of BSA with surfactant. • The binding of the surfactant leads to the partial unfolding of BSA. • The conformation of BSA predominately remains the α-helical.

  4. Surfactant screening of diesel-contaminated soil

    International Nuclear Information System (INIS)

    Peters, R.W.; Montemagno, C.D.; Shem, L.; Lewis, B.-A.

    1992-01-01

    At one installation in California, approximately 60,000 gal of No. 2 diesel fuel leaked into the subsurface environment, resulting in contamination at depths from 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. This paper summarizes a surfactant screening/surfactant flooding research program in which 22 surfactants were screened for their effectiveness in mobilizing the organics from the contaminated soil prior to bioremediation. Anionic surfactants resulted in the greatest degree of diesel mobilization. The most promising surfactants will be employed on contaminated soil samples obtained from the site

  5. Surfactant gene polymorphisms and interstitial lung diseases

    Directory of Open Access Journals (Sweden)

    Pantelidis Panagiotis

    2001-11-01

    Full Text Available Abstract Pulmonary surfactant is a complex mixture of phospholipids and proteins, which is present in the alveolar lining fluid and is essential for normal lung function. Alterations in surfactant composition have been reported in several interstitial lung diseases (ILDs. Furthermore, a mutation in the surfactant protein C gene that results in complete absence of the protein has been shown to be associated with familial ILD. The role of surfactant in lung disease is therefore drawing increasing attention following the elucidation of the genetic basis underlying its surface expression and the proof of surfactant abnormalities in ILD.

  6. Iron oxide nanoparticle-micelles (ION-micelles for sensitive (molecular magnetic particle imaging and magnetic resonance imaging.

    Directory of Open Access Journals (Sweden)

    Lucas W E Starmans

    Full Text Available BACKGROUND: Iron oxide nanoparticles (IONs are a promising nanoplatform for contrast-enhanced MRI. Recently, magnetic particle imaging (MPI was introduced as a new imaging modality, which is able to directly visualize magnetic particles and could serve as a more sensitive and quantitative alternative to MRI. However, MPI requires magnetic particles with specific magnetic properties for optimal use. Current commercially available iron oxide formulations perform suboptimal in MPI, which is triggering research into optimized synthesis strategies. Most synthesis procedures aim at size control of iron oxide nanoparticles rather than control over the magnetic properties. In this study, we report on the synthesis, characterization and application of a novel ION platform for sensitive MPI and MRI. METHODS AND RESULTS: IONs were synthesized using a thermal-decomposition method and subsequently phase-transferred by encapsulation into lipidic micelles (ION-Micelles. Next, the material and magnetic properties of the ION-Micelles were analyzed. Most notably, vibrating sample magnetometry measurements showed that the effective magnetic core size of the IONs is 16 nm. In addition, magnetic particle spectrometry (MPS measurements were performed. MPS is essentially zero-dimensional MPI and therefore allows to probe the potential of iron oxide formulations for MPI. ION-Micelles induced up to 200 times higher signal in MPS measurements than commercially available iron oxide formulations (Endorem, Resovist and Sinerem and thus likely allow for significantly more sensitive MPI. In addition, the potential of the ION-Micelle platform for molecular MPI and MRI was showcased by MPS and MRI measurements of fibrin-binding peptide functionalized ION-Micelles (FibPep-ION-Micelles bound to blood clots. CONCLUSIONS: The presented data underlines the potential of the ION-Micelle nanoplatform for sensitive (molecular MPI and warrants further investigation of the FibPep-ION-Micelle

  7. Adsorption of naphthalene and ozone on atmospheric air/ice interfaces coated with surfactants: a molecular simulation study.

    Science.gov (United States)

    Liyana-Arachchi, Thilanga P; Valsaraj, Kalliat T; Hung, Francisco R

    2012-03-15

    The adsorption of gas-phase naphthalene and ozone molecules onto air/ice interfaces coated with different surfactant species (1-octanol, 1-hexadecanol, or 1-octanal) was investigated using classical molecular dynamics (MD) simulations. Naphthalene and ozone exhibit a strong preference to be adsorbed at the surfactant-coated air/ice interfaces, as opposed to either being dissolved into the bulk of the quasi-liquid layer (QLL) or being incorporated into the ice crystals. The QLL becomes thinner when the air/ice interface is coated with surfactant molecules. The adsorption of both naphthalene and ozone onto surfactant-coated air/ice interfaces is enhanced when compared to bare air/ice interface. Both naphthalene and ozone tend to stay dissolved in the surfactant layer and close to the QLL, rather than adsorbing on top of the surfactant molecules and close to the air region of our systems. Surfactants prefer to orient at a tilted angle with respect to the air/ice interface; the angular distribution and the most preferred angle vary depending on the hydrophilic end group, the length of the hydrophobic tail, and the surfactant concentration at the air/ice interface. Naphthalene prefers to have a flat orientation on the surfactant coated air/ice interface, except at high concentrations of 1-hexadecanol at the air/ice interface; the angular distribution of naphthalene depends on the specific surfactant and its concentration at the air/ice interface. The dynamics of naphthalene molecules at the surfactant-coated air/ice interface slow down as compared to those observed at bare air/ice interfaces. The presence of surfactants does not seem to affect the self-association of naphthalene molecules at the air/ice interface, at least for the specific surfactants and the range of concentrations considered in this study.

  8. Surfactant -- Where Are We in 2003?

    Directory of Open Access Journals (Sweden)

    JF Lewis

    2004-01-01

    Full Text Available Surfactant research has progressed over the past several years to the extent that exogenous surfactant administration in patients with the acute respiratory distress syndrome (ARDS is now being evaluated. Unfortunately, clinical responses have been variable, and we now need to take a look at how surfactant is altered in this disease so that more effective treatment strategies can be developed. This review briefly discusses the biophysical and host defense properties of surfactant, the impact of mechanical ventilation (MV on the endogenous surfactant system and the most recent clinical data involving exogenous surfactant administration in patients with ARDS. Discussions regarding future directions of surfactant research both in ARDS and diseases other than acute lung injury are included.

  9. Polysarcosine-Based Lipids: From Lipopolypeptoid Micelles to Stealth-Like Lipids in Langmuir Blodgett Monolayers

    Directory of Open Access Journals (Sweden)

    Benjamin Weber

    2016-12-01

    Full Text Available Amphiphiles and, in particular, PEGylated lipids or alkyl ethers represent an important class of non-ionic surfactants and have become key ingredients for long-circulating (“stealth” liposomes. While poly-(ethylene glycol (PEG can be considered the gold standard for stealth-like materials, it is known to be neither a bio-based nor biodegradable material. In contrast to PEG, polysarcosine (PSar is based on the endogenous amino acid sarcosine (N-methylated glycine, but has also demonstrated stealth-like properties in vitro, as well as in vivo. In this respect, we report on the synthesis and characterization of polysarcosine based lipids with C14 and C18 hydrocarbon chains and their end group functionalization. Size exclusion chromatography (SEC and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS analysis reveals that lipopeptoids with a degree of polymerization between 10 and 100, dispersity indices around 1.1, and the absence of detectable side products are directly accessible by nucleophilic ring opening polymerization (ROP. The values for the critical micelle concentration for these lipopolymers are between 27 and 1181 mg/L for the ones with C18 hydrocarbon chain or even higher for the C14 counterparts. The lipopolypeptoid based micelles have hydrodynamic diameters between 10 and 25 nm, in which the size scales with the length of the PSar block. In addition, C18PSar50 can be incorporated in 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC monolayers up to a polymer content of 3%. Cyclic compression and expansion of the monolayer showed no significant loss of polymer, indicating a stable monolayer. Therefore, lipopolypeptoids can not only be synthesized under living conditions, but my also provide a platform to substitute PEG-based lipopolymers as excipients and/or in lipid formulations.

  10. Acidity Constants Determination of Triazine Dye Derivative in the presence of some Surfactants by Multiwavelength Spectrophotometric and Spectrofluorimetric

    Directory of Open Access Journals (Sweden)

    Ali Yeganeh Faal

    2014-03-01

    Full Text Available In this work, acidity constants protonated form of 4.4'-bis astilbene-2,2'-disulfonic-disodium salts (TRIAZ have been determined spectrophotometrically and spectrofluorimetrically at 25◦C and ionic strength of 0.1M KNO3. A program based on MCR-ALS applied for determination of acidity constants. The results show that the peak values of dye are influenced by the presence of anionic, cationic, and nonionic surfactants. The effects of sodium dodecyl sulfate (SDS, Triton X-100 (TX-100 and cetyl trimethyl ammonium bromide (CTAB as a surface-active agent on the acidic and basic forms, and the spectral properties of dye were studied. Also, we determined the critical micelle concentration (CMC for these surfactants by spectrophotometric and spectrofluorimetric triazine dye probes. In addition, by using of evolving factor analysis (EFA and multivariate curve resolution alternative least squares (MCR-ALS methods, acidity constants were acquired.

  11. A study of correlations between the release of drugs from petrolatum-based gels containing nonionic surfactants and some physical and physico-chemical characteristics of the gel systems.

    Science.gov (United States)

    Colo, G D; Nannipieri, E; Serafini, M F; Vitale, D

    1986-06-01

    Synopsis The in vitro release of benzocaine and 2-ethyIhexyl p-di-methylaminobenzoate (EH-PABA) from petrolatum-based gels either containing two nonionic surfactants, or not, was compared with some physical and/or physico-chemical characteristics of the drugs, the gels and the drug-gel systems. The surfactants had no effect on the release of EH-PABA, the less polar drug, whereas they decreased the release of benzocaine. Moreover, the release data show a complex dependence of diffusive properties of ben-zocaine on drug and surfactant concentration. Benzocaine appears to form mixed micelles with each of the two surfactants and/or undergoes self-aggregation phenomena within surfactant micelles. The results indicate that drug diffusion is influenced by gel porosity, drug molecular size and polarity and molecular interactions. Etude des corrélations entre la disponibilité des medicaments dans les gels a base de vaseline contenant des surfactifs non ioniques et quelques propriétés physiques et physicochimiques des gels.

  12. Small angle neutron scattering study of the gemini nonionic surfactant in heavy water solutions

    International Nuclear Information System (INIS)

    Rajewska, A

    2012-01-01

    The nonionic gemini surfactant α α'-[2,4,7,9-tetramethyl-5-decyne-4,7diyl]bis[ω hydroxyl-polyoxyethylene] (S-10) was investigated in heavy water solutions only for concentrations: 2.3%, 2.5%,3%, 3.4%, 4% and 5% at temperature 25 C with small angle neutron scattering (SANS) method. All of surfactants solutions were prepared using D 2 O (99.9% deuterated, Prikladnaia Chimia, St. Petersburg, Russia) as a solvent. The nonionic gemini surfactant S-10 was obtained from Air Products and Chemicals, Inc., and used without further purification. All SANS measurements were performed on V-4 SANS spectrometer at BENSC, Berlin (Germany). Neutrons were used in wavelength range of 0.02 - 4 nm - 1. For the measurements quartz cells of were used during experiment. Up to 14 such cells were placed in a holder. Results from experiment was calculated and evaluated with PCG 2.0 program from Graz University (Austria). In the investigated solutions two axis ellipsoidal micelles was observed.

  13. Two sides of the coin. Part 1. Lipid and surfactant self-assembly revisited.

    Science.gov (United States)

    Ninham, Barry W; Larsson, Kåre; Lo Nostro, Pierandrea

    2017-04-01

    Hofmeister, specific ion effects, hydration and van der Waals forces at and between interfaces are factors that determine curvature and microstructure in self assembled aggregates of surfactants and lipids; and in microemulsions. Lipid and surfactant head group interactions and between aggregates vary enormously and are highly specific. They act on the hydrophilic side of a bilayer, micelle or other self assembled aggregate. It is only over the last three decades that the origin of Hofmeister effects has become generally understood. Knowledge of their systematics now provides much flexibility in designing nanostructured fluids. The other side of the coin involves equally specific forces. These (opposing) forces work on the hydrophobic side of amphiphilic interfaces. They are due to the interaction of hydrocarbons and other "oils" with hydrophobic tails of surfactants and lipids. The specificity of oleophilic solutes in microemulsions and lipid membranes provides a counterpoint to Hofmeister effects and hydration. Together with global packing constraints these effects determine microstructure. Another factor that has hardly been recognised is the role of dissolved gas. This introduces further, qualitative changes in forces that prescribe microstructure. The systematics of these effects and their interplay are elucidated. Awareness of these competing factors facilitates formulation of self assembled nanostructured fluids. New and predictable geometries that emerge naturally provide insights into a variety of biological phenomena like anaesthetic and pheromone action and transmission of the nervous impulse (see Part 2). Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Field pilot test of surfactant-enhanced remediation of trichloroethane DNAPL in a sand aquifer

    International Nuclear Information System (INIS)

    Jackson, R.E.; Butler, G.W.; Londergan, J.T.; Mariner, P.E.; Pickens, J.F.; Fountain, J.C.

    1994-01-01

    The sequence of lacustrine and outwash deposits beneath a vapor degreasing operation at the Paducah Gaseous Division Plant, Kentucky, is contaminated with trichloroethane due to leakage from a sewer/sump line. A plume of dissolved trichloroethane (TCE) extends throughout an area of approximately 3 km 2 in the Regional Gravel Aquifer (RGA) which is located between 20 and 30 meters below ground surface. It is suspected that some 40,000 liters of TCE might have escaped into the subsurface at Paducah, most of which is still present in the lacustrine deposits and the underlying RGA as DNAPL. A field test to confirm the presence of TCE DNAPL in the sandy, upper portion of the RGA around a monitoring well and to test the efficiency of the surfactant for TCE solubilization is described. The aqueous concentrations of TCE in this well have consistently been measured at 300--550 mg TCE/L over a period of three years. The use of Capillary and Bond numbers to estimate the improbability of mobilization of DNAPL due to the lowering of the interfacial tension is described. The multiphase, multicomponent simulator UTCHEM was used to simulate both the injection and extraction of the surfactant solution and the solubilization of the TCE by the surfactant micelles

  15. Blue-Emitting Small Silica Particles Incorporating ZnSe-Based Nanocrystals Prepared by Reverse Micelle Method

    Directory of Open Access Journals (Sweden)

    Masanori Ando

    2007-01-01

    Full Text Available ZnSe-based nanocrystals (ca. 4-5 nm in diameter emitting in blue region (ca. 445 nm were incorporated in spherical small silica particles (20–40 nm in diameter by a reverse micelle method. During the preparation, alkaline solution was used to deposit the hydrolyzed alkoxide on the surface of nanocrystals. It was crucially important for this solution to include Zn2+ ions and surfactant molecules (thioglycolic acid to preserve the spectral properties of the final silica particles. This is because these substances in the solution prevent the surface of nanocrystals from deterioration by dissolution during processing. The resultant silica particles have an emission efficiency of 16% with maintaining the photoluminescent spectral width and peak wavelength of the initial colloidal solution.

  16. Structure and reactivity in amphiphile-water micelles

    International Nuclear Information System (INIS)

    Chevalier, Yves

    1985-01-01

    Following a review of the general properties of micelles, this report contains two parts: - A structural study of octylphosphate micelles. Important structural changes have been evidenced by mean of small angle neutron scattering as the electrical charge of the interface is varied. The NMR relaxation study of the conformation of the hydrocarbon chains has shown that the micellar core is disordered in contrast with the interface which is rather structured. The diffusion motions in the interface and the segmental motions of the chains are fast. - Studies on the reactivity in micelles have been carried out. A large micellar effect on the complexation of transition ions by amphiphilic ligands is evidenced. The problem of solute localization in micelles is developed with few examples. (author) [fr

  17. Interactions of casein micelles with calcium phosphate particles.

    Science.gov (United States)

    Tercinier, Lucile; Ye, Aiqian; Anema, Skelte G; Singh, Anne; Singh, Harjinder

    2014-06-25

    Insoluble calcium phosphate particles, such as hydroxyapatite (HA), are often used in calcium-fortified milks as they are considered to be chemically unreactive. However, this study showed that there was an interaction between the casein micelles in milk and HA particles. The caseins in milk were shown to bind to the HA particles, with the relative proportions of bound β-casein, αS-casein, and κ-casein different from the proportions of the individual caseins present in milk. Transmission electron microscopy showed no evidence of intact casein micelles on the surface of the HA particles, which suggested that the casein micelles dissociated either before or during binding. The HA particles behaved as ion chelators, with the ability to bind the ions contained in the milk serum phase. Consequently, the depletion of the serum minerals disrupted the milk mineral equilibrium, resulting in dissociation of the casein micelles in milk.

  18. Enzymatically triggered multifunctional delivery system based on hyaluronic acid micelles

    KAUST Repository

    Deng, Lin; Wang, Guangchao; Ren, Jian; Zhang, Bei; Yan, Jingjing; Li, Wengang; Khashab, Niveen M.

    2012-01-01

    (WI38). Higher Ch-HA micelles uptake was seen in cancer cells versus normal cells. Consequently, DOX release was elevated in cancer cells causing higher cytotoxicity and enhanced cell death. © 2012 The Royal Society of Chemistry.

  19. Synthesis and immobilization of polystyreneb-polyvinyltriethoxysilane micelles

    KAUST Repository

    Zhu, Saisai; Zhu, Hui; Xia, Ru; Feng, Xiaoshuang; Chen, Peng; Qian, Jiasheng; Cao, Ming; Yang, Bin; Miao, Jibin; Su, Lifen; Song, Changjiang

    2018-01-01

    Diblock copolymers polystyrene-block-polyvinyltriethoxysilane (PS-b-PVTES) were synthesized via atom transfer radical polymerization (ATRP), which self-assembled into spherical micelles in solvent of THF-methanol mixtures. The self

  20. Study on the surfactants present in atmospheric aerosols collected in the Okinawa Japan

    Science.gov (United States)

    Kamegawa, A.; Kasaba, T.; Shimabukuro, W.; Arakaki, T.

    2017-12-01

    The main constituent of atmospheric aerosols is organic substances, which occupy 20 to 70% of the mass. Organic matters in the aerosols contain organic acids, protein and humic acid, which behave similar to surfactants. Since surfactants contain both hydrophobic and hydrophilic functional groups in the molecule, they can play important roles in cloud formation and can affect climate change, but detailed mechanisms and magnitude are not well understood. In addition, surfactants can cause asthma, allergy, dry eye and so on. In this study, our aim is to characterize surfactants in the aerosols collected in different seasons in Okinawa, Japan. Atmospheric aerosols were collected at Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS) during Sep. 2013 and July 2014. Surfactants in the environment are comprised of artificially synthesized compounds and naturally derived organics so we only differentiate them into anionic and cationic surfactants. Colorimetric methods were used to determine the concentrations of anionic surfactants as methylene blue active substance (MBAS). Cationic surfactants were also measured by colorimetric method as disulfine blue active substance (DBAS) and showed always below detection limit. Thus, we only discuss anionic surfactants measured as MBAS. Water soluble organic carbon (WSOC) and metal concentrations were also measured for the same aerosol samples. Concentrations of MBAS in the studied samples were 2-3 times higher in spring, fall and winter than those collected in summer. MBAS concentration in the aerosols showed strong correlation with sulfate ion and WSOC, and slightly weaker correlation with nss-sulfate ion. Among the metals, only sodium ion showed a relatively strong correlation with MBAS concentrations. It is suggested that the anionic surfactants in the studied aerosols are mainly derived from marine sources.

  1. Seasonal evolution of anionic, cationic and non-ionic surfactant concentrations in coastal aerosols from Askö, Sweden

    Science.gov (United States)

    Gérard, Violaine; Nozière, Barbara; Baduel, Christine

    2015-04-01

    Surfactants present in atmospheric aerosols are expected to enhance the activation into cloud droplets by acting on one of the two key parameters of the Köhler equation: the surface tension, σ. But because the magnitude of this effect and its regional and temporal variability are still highly uncertain [1,2], various approaches have been developed to evidence it directly in the atmosphere. This work presents the analysis of surfactants present in PM2.5 aerosol fractions collected at the coastal site of Askö, Sweden (58° 49.5' N, 17° 39' E) from July to October 2010. The total surfactant fraction was extracted from the samples using an improved double extraction technique. Surface tension measurements performed with the pendant drop technique [3] indicated the presence of very strong surfactants (σ ~ 30 - 35 mN/m) in these aerosols. In addition, these extractions were combined with colorimetric methods to determine the anionic, cationic and non-ionic surfactant concentrations [4,5], and provided for the first time interference-free surfactant concentrations in atmospheric aerosols. At this site, the total surfactant concentration in the PM2.5 samples varied between 7 to 150 mM and was dominated by anionic and non-ionic ones. The absolute surface tension curves obtained for total surfactant fraction displayed Critical Micelle Concentrations (CMC) in the range 50 - 400 uM, strongly suggesting a biological origin for the surfactants. The seasonal evolution of these concentrations and their relationships with environmental or meteorological parameters at the site will be discussed. [1] Ekström, S., Nozière, B. et al., Biogeosciences, 2010, 7, 387 [2] Baduel, C., Nozière, B., Jaffrezo, J.-L., Atmos. Environ., 2012, 47, 413 [3] Nozière, B., Baduel, C., Jaffrezo, J.-L., Nat. Commun., 2014, 5, 1 [4] Latif, M. T.; Brimblecombe, P. Environ. Sci. Technol., 2004, 38, 6501 [5] Pacheco e Silva et al., Method to measure surfactant in fluid, 2013, US 2013/0337568 A1

  2. Nanofiltration: ion exchange system for effective surfactant removal from water solutions

    Directory of Open Access Journals (Sweden)

    I. Kowalska

    2014-12-01

    Full Text Available A system combining nanofiltration and ion exchange for highly effective separation of anionic surfactant from water solutions was proposed. The subjects of the study were nanofiltration polyethersulfone membranes and ion-exchange resins differing in type and structure. The quality of the treated solution was affected by numerous parameters, such as quality of the feed solution, membrane cut-off, resin type, dose and the solution contact time with the resin. A properly designed purification system made it possible to reduce the concentration of anionic surfactant below 1 mg L-1 from feed solutions containing surfactant in concentrations above the CMC value.

  3. Effect of counterion binding efficiency on structure and dynamics of wormlike micelles.

    Science.gov (United States)

    Oelschlaeger, C; Suwita, P; Willenbacher, N

    2010-05-18

    We have studied the effect of counterion binding efficiency on the linear viscoelastic properties of wormlike micelles formed from hexadecyltrimethylammonium bromide (CTAB) in the presence of different nonpenetrating inorganic salts: potassium bromide (KBr), sodium nitrate (NaNO(3)), and sodium chlorate (NaClO(3)). We have varied the salt/surfactant ratio R at fixed surfactant concentration of 350 mM. Results are compared to data for the system cetylpyridinium chloride (CPyCl) and the penetrating counterion sodium salicylate (NaSal) (Oelschlaeger, C.; Schopferer, M.; Scheffold, F.; Willenbacher, N. Langmuir 2009, 25, 716-723). Mechanical high-frequency rheology and diffusing wave spectroscopy (DWS) based tracer microrheology are used to determine the shear moduli G' and G'' in the frequency range from 0.1 Hz up to 1 MHz (Willenbacher, N.; Oelschlaeger, C.; Schopferer, M.; Fischer, P.; Cardinaux, F.; Scheffold, F. Phys. Rev. Lett. 2007, 99, 068302, 1-4). This enables us to determine the plateau modulus G(0), which is related to the cross-link density or mesh size of the entanglement network, the bending stiffness kappa (also expressed as persistence length l(p) = kappa/k(B)T) corresponding to the semiflexible nature of the micelles, and the scission energy E(sciss), which is related to their contour length. The viscosity maximum shifts to higher R values, and the variation of viscosity with R is less pronounced as the binding strength decreases. The plateau modulus increases with R at low ionic strength and is constant around the viscosity maximum; the increase in G(0) at high R, which is presumably due to branching, is weak compared to the system with penetrating counterion. The scission energy E(sciss) approximately = 20 k(B)T is independent of counterion binding efficiency irrespective of R and is slightly higher compared to the system CPyCl/NaSal, indicating that branching may be significant already at the viscosity maximum in this latter case. The micellar

  4. A neutron scattering study of triblock copolymer micelles

    Energy Technology Data Exchange (ETDEWEB)

    Gerstenberg, M.C.

    1997-11-01

    The thesis describes the neutron scattering experiments performed on poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymer micelles in aqueous solution. The studies concern the non-ionic triblock copolymer P85 which consists of two outer segments of 25 monomers of ethylene oxide attached to a central part of 40 monomers of propylene oxide. The amphiphilic character of P85 leads to formation of various structures in aqueous solution such as spherical micelles, rod-like structures, and a BCC liquid-crystal mesophase of spherical micelles. The present investigations are centered around the micellar structures. In the first part of this thesis a model for the micelle is developed for which an analytical scattering form factor can be calculated. The micelle is modeled as a solid sphere with tethered Gaussian chains. Good agreement was found between small-angle neutron scattering experiments and the form factor of the spherical P85 micelles. Above 60 deg. C some discrepancies were found between the model and the data which is possibly due to an elongation of the micelles. The second part focuses on the surface-induced ordering of the various micellar aggregates in the P85 concentration-temperature phase diagram. In the spherical micellar phase, neutron reflection measurements indicated a micellar ordering at the hydrophilic surface of quartz. Extensive modeling was performed based on a hard sphere description of the micellar interaction. By convolution of the distribution of hard spheres at a hard wall, obtained from Monte Carlo simulations, and the projected scattering length density of the micelle, a numerical expression was obtained which made it possible to fit the data. The hard-sphere-hard-wall model gave an excellent agreement in the bulk micellar phase. However, for higher concentrations (25 wt % P85) close to the transition from the micellar liquid into a micellar cubic phase, a discrepancy was found between the model and the

  5. Polymeric micelles for potentiated antiulcer and anticancer activities of naringin

    Science.gov (United States)

    Mohamed, Elham Abdelmonem; Abu Hashim, Irhan Ibrahim; Yusif, Rehab Mohammad; Shaaban, Ahmed Abdel Aziz; El-Sheakh, Ahmed Ramadan; Hamed, Mohammed Fawzy; Badria, Farid Abd Elreheem

    2018-01-01

    Naringin is one of the most interesting phytopharmaceuticals that has been widely investigated for various biological actions. Yet, its low water solubility, limited permeability, and suboptimal bioavailability limited its use. Therefore, in this study, polymeric micelles of naringin based on pluronic F68 (PF68) were developed, fully characterized, and optimized. The optimized formula was investigated regarding in vitro release, storage stability, and in vitro cytotoxicity vs different cell lines. Also, cytoprotection against ethanol-induced ulcer in rats and antitumor activity against Ehrlich ascites carcinoma in mice were investigated. Nanoscopic and nearly spherical 1:50 micelles with the mean diameter of 74.80±6.56 nm and narrow size distribution were obtained. These micelles showed the highest entrapment efficiency (EE%; 96.14±2.29). The micelles exhibited prolonged release up to 48 vs 10 h for free naringin. The stability of micelles was confirmed by insignificant changes in drug entrapment, particle size, and retention (%) (91.99±3.24). At lower dose than free naringin, effective cytoprotection of 1:50 micelles against ethanol-induced ulcer in rat model has been indicated by significant reduction in mucosal damage, gastric level of malondialdehyde, gastric expression of tumor necrosis factor-alpha, caspase-3, nuclear factor kappa-light-chain-enhancer of activated B cells, and interleukin-6 with the elevation of gastric reduced glutathione and superoxide dismutase when compared with the positive control group. As well, these micelles provoked pronounced antitumor activity assessed by potentiated in vitro cytotoxicity particularly against colorectal carcinoma cells and tumor growth inhibition when compared with free naringin. In conclusion, 1:50 naringin–PF68 micelles can be represented as a potential stable nanodrug delivery system with prolonged release and enhanced antiulcer as well as antitumor activities. PMID:29497294

  6. Nanoscale elastic modulus variation in loaded polymeric micelle reactors.

    Science.gov (United States)

    Solmaz, Alim; Aytun, Taner; Deuschle, Julia K; Ow-Yang, Cleva W

    2012-07-17

    Tapping mode atomic force microscopy (TM-AFM) enables mapping of chemical composition at the nanoscale by taking advantage of the variation in phase angle shift arising from an embedded second phase. We demonstrate that phase contrast can be attributed to the variation in elastic modulus during the imaging of zinc acetate (ZnAc)-loaded reverse polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) diblock co-polymer micelles less than 100 nm in diameter. Three sample configurations were characterized: (i) a 31.6 μm thick polystyrene (PS) support film for eliminating the substrate contribution, (ii) an unfilled PS-b-P2VP micelle supported by the same PS film, and (iii) a ZnAc-loaded PS-b-P2VP micelle supported by the same PS film. Force-indentation (F-I) curves were measured over unloaded micelles on the PS film and over loaded micelles on the PS film, using standard tapping mode probes of three different spring constants, the same cantilevers used for imaging of the samples before and after loading. For calibration of the tip geometry, nanoindentation was performed on the bare PS film. The resulting elastic modulus values extracted by applying the Hertz model were 8.26 ± 3.43 GPa over the loaded micelles and 4.17 ± 1.65 GPa over the unloaded micelles, confirming that phase contrast images of a monolayer of loaded micelles represent maps of the nanoscale chemical and mechanical variation. By calibrating the tip geometry indirectly using a known soft material, we are able to use the same standard tapping mode cantilevers for both imaging and indentation.

  7. A neutron scattering study of triblock copolymer micelles

    International Nuclear Information System (INIS)

    Gerstenberg, M.C.

    1997-11-01

    The thesis describes the neutron scattering experiments performed on poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymer micelles in aqueous solution. The studies concern the non-ionic triblock copolymer P85 which consists of two outer segments of 25 monomers of ethylene oxide attached to a central part of 40 monomers of propylene oxide. The amphiphilic character of P85 leads to formation of various structures in aqueous solution such as spherical micelles, rod-like structures, and a BCC liquid-crystal mesophase of spherical micelles. The present investigations are centered around the micellar structures. In the first part of this thesis a model for the micelle is developed for which an analytical scattering form factor can be calculated. The micelle is modeled as a solid sphere with tethered Gaussian chains. Good agreement was found between small-angle neutron scattering experiments and the form factor of the spherical P85 micelles. Above 60 deg. C some discrepancies were found between the model and the data which is possibly due to an elongation of the micelles. The second part focuses on the surface-induced ordering of the various micellar aggregates in the P85 concentration-temperature phase diagram. In the spherical micellar phase, neutron reflection measurements indicated a micellar ordering at the hydrophilic surface of quartz. Extensive modeling was performed based on a hard sphere description of the micellar interaction. By convolution of the distribution of hard spheres at a hard wall, obtained from Monte Carlo simulations, and the projected scattering length density of the micelle, a numerical expression was obtained which made it possible to fit the data. The hard-sphere-hard-wall model gave an excellent agreement in the bulk micellar phase. However, for higher concentrations (25 wt % P85) close to the transition from the micellar liquid into a micellar cubic phase, a discrepancy was found between the model and the

  8. Structure of sodium alkyl sulphate micelles

    International Nuclear Information System (INIS)

    Vass, Sz.

    1990-05-01

    Micellar aggregation numbers of aggregated sodium octyl, decyl, dodecyl and tetradecyl sulphate molecules obtained from small-angle neutron scattering (SANS) measurements are reported. The surfactant concentration and solution temperature were varied systematically. A survey of the physical models and evaluation algorithms applied for SANS are presented. By utilizing a new least square fitting algorithm, the formation and annihilation parameters of orthopositronium in the micellar pseudophase and in the aqueous solvent is deduced by evaluating positron lifetime spectra measured by conventional technqiues. (R.P.) 157 refs.; 10 figs

  9. Structural and Interfacial Properties of Hyperbranched-Linear Polymer Surfactant.

    Science.gov (United States)

    Qiang, Taotao; Bu, Qiaoqiao; Huang, Zhaofeng; Wang, Xuechuan

    2014-01-01

    With oleic acid grafting modification, a series of hyperbranched-linear polymer surfactants (HLPS) were prepared by hydroxyl-terminated hyperbranched polymer (HBP), which was gained through a step synthesis method using trimethylolpropane and AB 2 monomer. The AB 2 monomers were obtained through the Michael addition reaction of methyl acrylate and diethanol amine. The structures of HLPS were characterised by Fourier transform infrared spectrophotometer and nuclear magnetic resonance (NMR), which indicated that HBP was successfully modified by oleic acid. Furthermore, the properties of surface tension and critical micelle concentration of HLPS solution showed that HLPS can significantly reduce the surface tension of water. The morphology of the HLPS solution was characterised by dynamic light scattering, which revealed that HLPS exhibited a nonmonotonic appearance in particle size at different scattering angles owing to the different replaced linear portions. The relationships of the surface pressure to monolayer area and time were measured using the Langmuir-Blodgett instrument, which showed that the surface tension of monolayer molecules increased with the increasing of hydrophobic groups. In addition, the interface conditions of different replaced HLPS solutions were simulated.

  10. Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

    Directory of Open Access Journals (Sweden)

    Mahdi ES

    2011-06-01

    Full Text Available Elrashid Saleh Mahdi1, Mohamed HF Sakeena1, Muthanna F Abdulkarim1, Ghassan Z Abdullah1,3, Munavvar Abdul Sattar2, Azmin Mohd Noor11Department of Pharmaceutical Technology, 2Department of Physiology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia; 3Department of Pharmaceutical Technology, International Medical University, Bukit Jalil, Kuala Lumpur, MalaysiaBackground: The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters.Methods: Nonionic surfactant blends of Tween® and Tween®/Span® series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween® 80 and five blends of Tween® 80/Span® 80 and Tween® 80/Span® 85 in the hydrophilic-lipophilic balance (HLB value range of 10.7–14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature.Results: High solubilization capacity was obtained by Tween® 80 compared with other surfactants of Tween® series. High HLB blends of Tween® 80/Span® 85 and Tween® 80/Span® 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween® 80/Span® 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween® 80 and the oleyl group of the palm kernel oil esters.Conclusion: This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant

  11. Potential application of surfactant systems in formulation of dosage forms with slightly soluble substances

    Directory of Open Access Journals (Sweden)

    Ibrić Svetlana R.

    2012-01-01

    Full Text Available In order to achieve fast release of ibuprofen, slightly soluble model substance (0.52104 mol/l, surfactant systems for oral use with different PEG-40 hydrogenated castor oil (C/diethylene glycol monoethyl ether (T ratios were investigated. Comparison between dissolution profiles for ibuprofen from formulated systems and from two commercial products, film tablets and soft capsules, is presented in this paper. Photon correlation spectroscopy has shown that after high dilution with water, surfactant systems were able to form micellar solutions. The size of micelles varies from 14.8 ± 0,075 nm to 16.2 ± 0,021 nm with increasing C/T ratio from 1:2 to 2:1. Although with increasing content of PEG-40 hydrogenated castor oil larger micelles have formed, lower values of polydispersity index indicated that more homogeneous distribution of micelles size was gained. Conductometric analysis has demonstrated that system composing of C/T ratio 2:1, has shown most pronounced interaction between droplets, which can be seen as high rise of electrical conductivity with increasing water content (% (wwater/wtotal in the sample. No significant difference in percolation threshold between formulations with different C/T ratios was observed. Different surfactant systems were adsorbed on magnesium aluminometasilicate, as adsorbent with high specific active surface (≈300 m2/g, in order to investigate potential influence of adsorbent on ibuprofen dissolution rate. Formulated systems, with or without adsorbent were filled in hard gelatin capsules. The dissolution profiles of ibuprofen from different formulations were obtained in 30 minutes by dissolution apparatus with rotating baskets and compared with dissolution profiles of ibuprofen from commercial products. For formulations without adsorbent faster release of ibuprofen in first minutes of dissolution test, showed formulations with C/T ratio 2:1 and 1:1. Magnesium aluminometasilicate, as adsorbent with high specific

  12. Adsorption of dimeric surfactants in lamellar silicates

    Energy Technology Data Exchange (ETDEWEB)

    Balcerzak, Mateusz; Pietralik, Zuzanna [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Domka, Ludwik [Department of Metalorganic Chemistry, Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań (Poland); Skrzypczak, Andrzej [Institute of Chemical Technology, Poznań University of Technology, Berdychowo 4, 60-965 Poznań (Poland); Kozak, Maciej, E-mail: mkozak@amu.edu.pl [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

    2015-12-01

    Highlights: • The intercalation of dimeric surfactants changed the morphology of MMT samples. • XRD indicated structures formed by surfactant molecules in interlayer space. • The four-step thermal decomposition of dimeric surfactant, confirms intercalation. - Abstract: The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay – hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1′-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d{sub 001}) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH{sub 2} and CH{sub 3} groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

  13. Micelle swelling agent derived cavities for increasing hydrophobic organic compound removal efficiency by mesoporous micelle@silica hybrid materials

    KAUST Repository

    Shi, Yifeng; Li, Bin; Wang, Peng; Dua, Rubal; Zhao, Dongyuan

    2012-01-01

    Mesoporous micelle@silica hybrid materials with 2D hexagonal mesostructures were synthesized as reusable sorbents for hydrophobic organic compounds (HOCs) removal by a facile one-step aqueous solution synthesis using 3-(trimethoxysily)propyl

  14. Synthesis of sol–gel silica particles in reverse micelles with mixed-solvent polar cores: tailoring nanoreactor structure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Bürglová, Kristýna; Hlaváč, Jan [Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry (Czech Republic); Bartlett, John R., E-mail: jbartlett@usc.edu.au [University of the Sunshine Coast, Faculty of Science, Health, Education and Engineering (Australia)

    2015-07-15

    In this paper, we describe a new approach for producing metal oxide nano- and microparticles via sol–gel processing in confined media (sodium bis(2-ethylhexyl)sulfosuccinate reverse micelles), in which the chemical and physical properties of the polar aqueous core of the reverse micelles are modulated by the inclusion of a second polar co-solvent. The co-solvents were selected for their capacity to solubilise compounds with low water solubility and included dimethylsulfoxide, dimethylformamide, ethylene glycol, n-propanol, dimethylacetamide and N-methylpyrrolidone. A broad range of processing conditions across the sodium bis(2-ethylhexyl)sulfosuccinate/cyclohexane/water phase diagram were identified that are suitable for preparing particles with dimensions <50 to >500 nm. In contrast, only a relatively narrow range of processing conditions were suitable for preparing such particles in the absence of the co-solvents, highlighting the role of the co-solvent in modulating the properties of the polar core of the reverse micelles. A mechanism is proposed that links the interactions between the various reactive sites on the polar head group of the surfactant and the co-solvent to the nucleation and growth of the particles.

  15. Adsorption of sugar surfactants at the air/water interface.

    Science.gov (United States)

    Varga, Imre; Mészáros, Róbert; Stubenrauch, Cosima; Gilányi, Tibor

    2012-08-01

    The adsorption isotherms of n-decyl-β-D-glucoside (β-C(10)G(1)) as well as various n-alkyl-β-D-maltosides (β-C(n)G(2)) with n=8, 10, 12 and 14 were determined from surface tension measurements. Based on the analysis of the adsorption isotherms, the total free energy change of adsorption was determined and a novel method was proposed to determine the maximum adsorbed amount of surfactant. It can be concluded that the driving force for adsorption first increases with increasing adsorbed amount of the sugar surfactants and then levels off in a plateau. This peculiar behaviour is interpreted as formation of a thin liquid-like alkane film of overlapping alkyl chains at the air/water interface once a certain adsorbed amount is exceeded. The driving force of adsorption depends on the alkyl chain length only and is not affected by the type of the head group. The hydrophobic contribution to the standard free energy change of adsorption was compared with the values of sodium alkylsulfate and alkyltrimethylammonium bromide surfactants. This comparison reveals that the hydrophobic driving force of adsorption is the largest for the sodium alkylsulfates, whereas it is the same for the sugar surfactants and the alkyltrimethylammonium bromides. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Impact of Surface Active Ionic Liquids on the Cloud Points of Nonionic Surfactants and the Formation of Aqueous Micellar Two-Phase Systems.

    Science.gov (United States)

    Vicente, Filipa A; Cardoso, Inês S; Sintra, Tânia E; Lemus, Jesus; Marques, Eduardo F; Ventura, Sónia P M; Coutinho, João A P

    2017-09-21

    Aqueous micellar two-phase systems (AMTPS) hold a large potential for cloud point extraction of biomolecules but are yet poorly studied and characterized, with few phase diagrams reported for these systems, hence limiting their use in extraction processes. This work reports a systematic investigation of the effect of different surface-active ionic liquids (SAILs)-covering a wide range of molecular properties-upon the clouding behavior of three nonionic Tergitol surfactants. Two different effects of the SAILs on the cloud points and mixed micelle size have been observed: ILs with a more hydrophilic character and lower critical packing parameter (CPP formation of smaller micelles and concomitantly increase the cloud points; in contrast, ILs with a more hydrophobic character and higher CPP (CPP ≥ 1) induce significant micellar growth and a decrease in the cloud points. The latter effect is particularly interesting and unusual for it was accepted that cloud point reduction is only induced by inorganic salts. The effects of nonionic surfactant concentration, SAIL concentration, pH, and micelle ζ potential are also studied and rationalized.

  17. Diketopyrrolopyrrole Amphiphile-Based Micelle-Like Fluorescent Nanoparticles for Selective and Sensitive Detection of Mercury(II) Ions in Water.

    Science.gov (United States)

    Nie, Kaixuan; Dong, Bo; Shi, Huanhuan; Liu, Zhengchun; Liang, Bo

    2017-03-07

    A technique for encapsulating fluorescent organic probes in a micelle system offers an important alternative method to manufacture water-soluble organic nanoparticles (ONPs) for use in sensing Hg 2+ . This article reports on a study of a surfactant-free micelle-like ONPs based on a 3,6-di(2-thienyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (TDPP) amphiphile, (2-(2-(2-methoxyethoxy)ethyl)-3,6-di(2-thiophyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (NDPP) fabricated to monitor Hg 2+ in water. NDPP was synthesized through a simple one-step modification of a commercially available dye TDPP with a flexible and hydrophilic alkoxy. This study reports, for the first time, that TDPP dyes can respond reversibly, sensitively, and selectively to Hg 2+ through TDPP-Hg-TDPP complexation, similar to the well-known thymine(T)-Hg-thymine(T) model and the accompanying molecular aggregation. Interestingly, transmission electron microscopy (TEM) and dynamic light scattering (DLS) confirmed that, in water, NDPP forms loose micelle-like fluorescent ONPs with a hydrohobic TDPP portion encapsulated inside. These micelle-like nanoparticles offer an ideal location for TDPP-Hg complexation with a modest molecular aggregation, thereby providing both clear visual and spectroscopic signals for Hg 2+ sensing. An estimated detection limit of 11 nM for Hg 2+ sensing with this NDPP nanoparticle was obtained. In addition, NDPP ONPs show good water solubility and high selectivity to Hg 2+ in neutral or alkalescent water. It was superior to most micelle-based nanosensors, which require a complicated process in the selection or synthesis of suitable surfactants. The determinations in real samples (river water) were made and satisfactory results were achieved. This study provides a low-cost strategy for fabricating small molecule-based fluorescent nanomaterials for use in sensing Hg 2+ . Moreover, the NDPP nanoparticles show potential ability in Hg 2+ ion adsorption and recognization of cysteine

  18. Effect of Cationic Surfactant Head Groups on Synthesis, Growth and Agglomeration Behavior of ZnS Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mehta SK

    2009-01-01

    Full Text Available Abstract Colloidal nanodispersions of ZnS have been prepared using aqueous micellar solution of two cationic surfactants of trimethylammonium/pyridinium series with different head groups i.e., cetyltrimethylammonium chloride (CTAC and cetyltrimethylpyridinium chloride (CPyC. The role of these surfactants in controlling size, agglomeration behavior and photophysical properties of ZnS nanoparticles has been discussed. UV–visible spectroscopy has been carried out for determination of optical band gap and size of ZnS nanoparticles. Transmission electron microscopy and dynamic light scattering were used to measure sizes and size distribution of ZnS nanoparticles. Powder X-ray analysis (Powder XRD reveals the cubic structure of nanocrystallite in powdered sample. The photoluminescence emission band exhibits red shift for ZnS nanoparticles in CTAC compared to those in CPyC. The aggregation behavior in two surfactants has been compared using turbidity measurements after redispersing the nanoparticles in water. In situ evolution and growth of ZnS nanoparticles in two different surfactants have been compared through time-dependent absorption behavior and UV irradiation studies. Electrical conductivity measurements reveal that CPyC micelles better stabilize the nanoparticles than that of CTAC.

  19. Study of the effect of surfactants on extraction and determination of polyphenolic compounds and antioxidant capacity of fruits extracts.

    Directory of Open Access Journals (Sweden)

    Reza Hosseinzadeh

    Full Text Available Micelle/water mixed solutions of different surface active agents were studied for their effectiveness in the extraction of polyphenolic compounds from various varieties of apples from west Azerbaijan province in Iran. The total content of polyphenolic compound in fruit extracts were determined using ferrous tartrate and Folin-Ciocalteu assays methods and chromatographic methods and compared with theme. High performance liquid chromatography is one of the most common and important methods in biochemical compound identification. The effect of pH, ionic strength, surfactant type, surfactant concentration, extraction time and common organic solvent in the apple polyphenolics extractions was studied using HPLC-DAD. Mixtures of surfactants, water and methanol at various ratios were examined and micellar-water solutions of Brij surfactant showed the highest polyphenol extraction efficiency. Optimum conditions for the extraction of polyphenolic compounds from apple occurred at 7 mM Brij35, pH 3. Effect of ionic strength on extraction was determined and 2% (W/V potassium Chloride was determined to be the optimum salt concentration. The procedure worked well with an ultrasound bath. Total antioxidant capacity also was determined in this study. The method can be safely scaled up for pharmaceutical applications.

  20. Properties of surfactant films in water-in-CO2 microemulsions obtained by small-angle neutron scattering.

    Science.gov (United States)

    Yan, Ci; Sagisaka, Masanobu; James, Craig; Rogers, Sarah; Alexander, Shirin; Eastoe, Julian

    2014-12-01

    The formation, stability and structural properties of normal liquid phase microemulsions, stabilized by hydrocarbon surfactants, comprising water and hydrocarbon oils can be interpreted in terms of the film bending rigidity (energy) model. Here, this model is tested for unusual water-in-CO2 (w/c) microemulsions, formed at high pressure with supercritical CO2 (sc-CO2) as a solvent and fluorinated surfactants as stabilizers. Hence, it is possible to explore the generality of this model for other types of microemulsions. High Pressure Small-Angle Neutron Scattering (HP-SANS) has been used to study w/c microemulsions, using contrast variation to highlight scattering from the stabilizing fluorinated surfactant films: these data show clear evidence for spherical core-shell structures for the microemulsion droplets. The results extend understanding of w/c microemulsions since previous SANS studies are based only on scattering from water core droplets. Here, detailed structural parameters for the surfactant films, such as thickness and film bending energy, have been extracted from the core-shell SANS profiles revealed by controlled contrast variation. Furthermore, at reduced CO2 densities (∼0.7gcm(-3)), elongated cylindrical droplet structures have been observed, which are uncommon for CO2 microemulsions/emulsions. The implications of the presence of cylindrical micelles and droplets for applications of CO2, and viscosity enhancements are discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Surface induced ordering of micelles at the solid-liquid interface

    International Nuclear Information System (INIS)

    Gerstenberg, M.C.; Pedersen, J.S.; Smith, G.S.

    1998-01-01

    The surface induced ordering of triblock copolymer micelles in aqueous solution was measured with neutron reflectivity far above the critical micelle concentration. The scattering length density profiles showed a clear indication of ordered layers of micelles perpendicular to a quartz surface. The structure and interactions of the micelles were modeled in detail. The convolution of the center distribution of the micelles, obtained from Monte Carlo simulations of hard spheres at a hard wall, and the projected density of the micelle showed excellent agreement with the experimental profiles. copyright 1998 The American Physical Society

  2. Surface induced ordering of micelles at the solid-liquid interface

    DEFF Research Database (Denmark)

    Gerstenberg, M.C.; Pedersen, J.S.; Smith, G.S.

    1998-01-01

    The surface induced ordering of triblock copolymer micelles in aqueous solution was measured with neutron reflectivity far above the critical micelle concentration. The scattering length density profiles showed a clear indication of ordered layers of micelles perpendicular to a quartz surface....... The structure and interactions of the micelles were modeled in detail. The convolution of the center distribution of the micelles, obtained from Monte Carlo simulations of hard spheres at a hard wall, and the projected density of the micelle showed excellent agreement with the experimental profiles. [S1063-651X...

  3. Phase transitions in surfactant monolayers

    International Nuclear Information System (INIS)

    Casson, B.D.

    1998-01-01

    Two-dimensional phase transitions have been studied in surfactant monolayers at the air/water interface by sum-frequency spectroscopy and ellipsometry. In equilibrium monolayers of medium-chain alcohols C n H 2n+1 OH (n = 9-14) a transition from a two-dimensional crystalline phase to a liquid was observed at temperatures above the bulk melting point. The small population of gauche defects in the solid phase increased only slightly at the phase transition. A model of the hydrocarbon chains as freely rotating rigid rods allowed the area per molecule and chain tilt in the liquid phase to be determined. The area per molecule, chain tilt and density of the liquid phase all increased with increasing chain length, but for each chain length the density was higher than in a bulk liquid hydrocarbon. In a monolayer of decanol adsorbed at the air/water interface a transition from a two-dimensional liquid to a gas was observed. A clear discontinuity in the coefficient of ellipticity as a function of temperature showed that the transition is first-order. This result suggests that liquid-gas phase transitions in surfactant monolayers may be more widespread than once thought. A solid-liquid phase transition has also been studied in mixed monolayers of dodecanol with an anionic surfactant (sodium dodecyl sulphate) and with a homologous series of cationic surfactants (alkyltrimethylammonium bromides: C n TABs, n = 12, 14, 16). The composition and structure of the mixed monolayers was studied above and below the phase transition. At low temperatures the mixed monolayers were as densely packed as a monolayer of pure dodecanol in its solid phase. At a fixed temperature the monolayers under-went a first-order phase transition to form a phase that was less dense and more conformationally disordered. The proportion of ionic surfactant in the mixed monolayer was greatest in the high temperature phase. As the chain length of the C n TAB increased the number of conformational defects

  4. Effect of surfactants on separate hydrolysis fermentation and simultaneous saccharification fermentation of pretreated lodgepole pine.

    Science.gov (United States)

    Tu, Maobing; Zhang, Xiao; Paice, Mike; McFarlane, Paul; Saddler, Jack N

    2009-01-01

    The effects of surfactants addition on enzymatic hydrolysis and subsequent fermentation of steam exploded lodgepole pine (SELP) and ethanol pretreated lodgepole pine (EPLP) were investigated in this study. Supplementing Tween 80 during cellulase hydrolysis of SELP resulted in a 32% increase in the cellulose-to-glucose yield. However, little improvement was obtained from hydrolyzing EPLP in the presence of the same amount of surfactant. The positive effect of surfactants on SELP hydrolysis led to an increase in final ethanol yield after the fermentation. It was found that the addition of surfactant led to a substantial increase in the amount of free enzymes in the 48 h hydrolysates derived from both substrates. The effect of surfactant addition on final ethanol yield of simultaneous saccharification and fermentation (SSF) was also investigated by using SELP in the presence of additional furfural and hydroxymethylfurfural (HMF). The results showed that the surfactants slightly increased the conversion rates of furfural and HMF during SSF process by Saccharomyces cerevisiae. The presence of furfural and HMF at the experimental concentrations did not affect the final ethanol concentration either. The strategy of applying surfactants in cellulase recycling to reduce enzyme cost is presented. (c) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009.

  5. Numerical Study of Surfactant Dynamics during Emulsification in a T-Junction Microchannel.

    Science.gov (United States)

    Riaud, Antoine; Zhang, Hao; Wang, Xueying; Wang, Kai; Luo, Guangsheng

    2018-04-18

    Microchannel emulsification requires large amounts of surfactant to prevent coalescence and improve emulsions lifetime. However, most numerical studies have considered surfactant-free mixtures as models for droplet formation in microchannels, without taking into account the distribution of surfactant on the droplet surface. In this paper, we investigate the effects of nonuniform surfactant coverage on the microfluidic flow pattern using an extended lattice-Boltzmann model. This numerical study, supported by micro-particle image velocimetry experiments, reveals the likelihood of uneven distribution of surfactant during the droplet formation and the appearance of a stagnant cap. The Marangoni effect affects the droplet breakup by increasing the shear rate. According to our results, surfactant-free and surfactant-rich droplet formation processes are qualitatively different, such that both the capillary number and the Damköhler number should be considered when modeling the droplet generation in microfluidic devices. The limitations of traditional volume and pressure estimation methods for determining the dynamic interfacial tension are also discussed on the basis of the simulation results.

  6. Surfactant proteins gene variants in premature newborn infants with severe respiratory distress syndrome.

    Science.gov (United States)

    Somaschini, Marco; Presi, Silvia; Ferrari, Maurizio; Vergani, Barbara; Carrera, Paola

    2017-12-19

    Genetic surfactant dysfunction causes respiratory failure in term and near-term newborn infants, but little is known of such condition in prematures. We evaluated genetic surfactant dysfunction in premature newborn infants with severe RDS. A total of 68 preterm newborn infants with gestational age ≤32 weeks affected by unusually severe RDS were analysed for mutations in SFTPB, SFTPC and ABCA3. Therapies included oxygen supplementation, nasal CPAP, different modalities of ventilatory support, administration of exogenous surfactant, inhaled nitric oxide and steroids. Molecular analyses were performed on genomic DNA extracted from peripheral blood and Sanger sequencing of whole gene coding regions and intron junctions. In one case histology and electron microscopy on lung tissue was performed. Heterozygous previously described rare or novel variants in surfactant proteins genes ABCA3, SFTPB and SFTPC were identified in 24 newborn infants. In total, 11 infants died at age of 2 to 6 months. Ultrastructural analysis of lung tissue of one infant showed features suggesting ABCA3 dysfunction. Rare or novel genetic variants in genes encoding surfactant proteins were identified in a large proportion (35%) of premature newborn infants with particularly severe RDS. We speculate that interaction of developmental immaturity of surfactant production in association with abnormalities of surfactant metabolism of genetic origin may have a synergic worsening phenotypic effect.

  7. The Biophysical Function of Pulmonary Surfactant

    OpenAIRE

    Rugonyi, Sandra; Biswas, Samares C.; Hall, Stephen B.

    2008-01-01

    Pulmonary surfactant lowers surface tension in the lungs. Physiological studies indicate two key aspects of this function: that the surfactant film forms rapidly; and that when compressed by the shrinking alveolar area during exhalation, the film reduces surface tension to very low values. These observations suggest that surfactant vesicles adsorb quickly, and that during compression, the adsorbed film resists the tendency to collapse from the interface to form a three-dimensional bulk phase....

  8. Acute Pathophysiological Effects of Intratracheal Instillation of Budesonide and Exogenous Surfactant in a Neonatal Surfactant-depleted Piglet Model

    Directory of Open Access Journals (Sweden)

    Chia-Feng Yang

    2010-08-01

    Conclusions: Intratracheal instillation of surfactant or surfactant plus budesonide can improve oxygenation and pulmonary histologic outcome in neonatal surfactant-depleted lungs. The additional use of budesonide does not disturb the function of the exogenous surfactant. Intratracheal administration of a corticosteroid combined with surfactant may be an effective method for alleviating local pulmonary inflammation in severe RDS.

  9. Amphipathic dextran-doxorubicin prodrug micelles for solid tumor therapy.

    Science.gov (United States)

    Jin, Rong; Guo, Xuelian; Dong, Lingli; Xie, Enyuan; Cao, Aoneng

    2017-10-01

    A group of micelles self-assembled from deoxycholic acid-doxorubicin-conjugated dextran (denoted as Dex-DCA-DOX) prodrugs were designed and prepared for pH-triggered drug release and cancer chemotherapy. These prodrugs could be successfully produced by chemically coupling hydrophobic deoxycholic acid (DCA) to dextran hydrazine (denoted as Dex-NHNH 2 ) and hydrazone linker formation between doxorubicin (DOX) and Dex-NHNH 2 . These Dex-DCA-DOX prodrugs self-assembled to form micelles under physiological conditions with varied particle sizes depending on molecular weight of dextran, degree of substitution (DS) of DCA and DOX. After optimization, Dex10k-DCA9-DOX5.5 conjugate comprising dextran of 10kDa, DCA of DS 9 and DOX loading content of 5.5wt%, formed the micelles with the smallest size (110nm). These prodrug micelles could slowly liberate DOX under physiological conditions but efficiently released the drug at an acidified endosomal pH by the hydrolysis of acid-labile hydrazone linker. In vitro cytotoxicity experiment indicated that Dex10k-DCA9-DOX5.5 micelles exerted marked antitumor activity against MCF-7 and SKOV-3 cancer cells. Besides, intravenous administration of the micelles afforded growth inhibition of SKOV-3 tumor bearing in nude mice at a dosage of 2.5mg per kg with anti-cancer efficacy comparable to free DOX-chemotherapy but low systemic toxicity. This study highlights the feasibility of bio-safe and efficient dextran-based prodrug micelles designed for cancer chemotherapy. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Remediation using trace element humate surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Riddle, Catherine Lynn; Taylor, Steven Cheney; Bruhn, Debra Fox

    2016-08-30

    A method of remediation at a remediation site having one or more undesirable conditions in which one or more soil characteristics, preferably soil pH and/or elemental concentrations, are measured at a remediation site. A trace element humate surfactant composition is prepared comprising a humate solution, element solution and at least one surfactant. The prepared trace element humate surfactant composition is then dispensed onto the remediation site whereby the trace element humate surfactant composition will reduce the amount of undesirable compounds by promoting growth of native species activity. By promoting native species activity, remediation occurs quickly and environmental impact is minimal.

  11. Fluorescent visualization of a spreading surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Fallest, David W; Lichtenberger, Adele M; Fox, Christopher J; Daniels, Karen E, E-mail: kdaniel@ncsu.ed [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States)

    2010-07-15

    The spreading of surfactants on thin films is an industrially and medically important phenomenon, but the dynamics are highly nonlinear and visualization of the surfactant dynamics has been a long-standing experimental challenge. We perform the first quantitative, spatiotemporally resolved measurements of the spreading of an insoluble surfactant on a thin fluid layer. During the spreading process, we directly observe both the radial height profile of the spreading droplet and the spatial distribution of the fluorescently tagged surfactant. We find that the leading edge of a spreading circular layer of surfactant forms a Marangoni ridge in the underlying fluid, with a trough trailing the ridge as expected. However, several novel features are observed using the fluorescence technique, including a peak in the surfactant concentration that trails the leading edge, and a flat, monolayer-scale spreading film that differs from concentration profiles predicted by current models. Both the Marangoni ridge and the surfactant leading edge can be described to spread as R{approx}t{sup {delta}}. We find spreading exponents {delta}{sub H}{approx}0.30 and {delta}{sub {Gamma}}{approx}0.22 for the ridge peak and surfactant leading edge, respectively, which are in good agreement with theoretical predictions of {delta}=1/4. In addition, we observe that the surfactant leading edge initially leads the peak of the Marangoni ridge, with the peak later catching up to the leading edge.

  12. Role of adsorbed surfactant in the reaction of aryl diazonium salts with single-walled carbon nanotubes.

    Science.gov (United States)

    Hilmer, Andrew J; McNicholas, Thomas P; Lin, Shangchao; Zhang, Jingqing; Wang, Qing Hua; Mendenhall, Jonathan D; Song, Changsik; Heller, Daniel A; Barone, Paul W; Blankschtein, Daniel; Strano, Michael S

    2012-01-17

    Because covalent chemistry can diminish the optical and electronic properties of single-walled carbon nanotubes (SWCNTs), there is significant interest in developing methods of controllably functionalizing the nanotube sidewall. To date, most attempts at obtaining such control have focused on reaction stoichiometry or strength of oxidative treatment. Here, we examine the role of surfactants in the chemical modification of single-walled carbon nanotubes with aryl diazonium salts. The adsorbed surfactant layer is shown to affect the diazonium derivatization of carbon nanotubes in several ways, including electrostatic attraction or repulsion, steric exclusion, and direct chemical modification of the diazonium reactant. Electrostatic effects are most pronounced in the cases of anionic sodium dodecyl sulfate and cationic cetyltrimethylammonium bromide, where differences in surfactant charge can significantly affect the ability of the diazonium ion to access the SWCNT surface. For bile salt surfactants, with the exception of sodium cholate, we find that the surfactant wraps tightly enough such that exclusion effects are dominant. Here, sodium taurocholate exhibits almost no reactivity under the explored reaction conditions, while for sodium deoxycholate and sodium taurodeoxycholate, we show that the greatest extent of reaction is observed among a small population of nanotube species, with diameters between 0.88 and 0.92 nm. The anomalous reaction of nanotubes in this diameter range seems to imply that the surfactant is less effective at coating these species, resulting in a reduced surface coverage on the nanotube. Contrary to the other bile salts studied, sodium cholate enables high selectivity toward metallic species and small band gap semiconductors, which is attributed to surfactant-diazonium coupling to form highly reactive diazoesters. Further, it is found that the rigidity of anionic surfactants can significantly influence the ability of the surfactant layer to

  13. Surfactant nebulisation : lung function, surfactant distribution and pulmonary blood flow distribution in lung lavaged rabbits

    NARCIS (Netherlands)

    Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

    1997-01-01

    Objective: Surfactant nebulisation is a promising alternative to surfactant instillation in newborns with the respiratory distress syndrome. Although less surfactant is deposited in the lung, it improves gas exchange, probably due to a superior distribution. We hypothesize that a more uniform

  14. Soil remediation: humic acids as natural surfactants in the washings of highly contaminated soils

    International Nuclear Information System (INIS)

    Conte, Pellegrino; Agretto, Anna; Spaccini, Riccardo; Piccolo, Alessandro

    2005-01-01

    The remediation of the highly contaminated site around the former chemical plant of ACNA (near Savona) in Northern Italy is a top priority in Italy. The aim of the present work was to contribute in finding innovative and environmental-friendly technology to remediate soils from the ACNA contaminated site. Two soils sampled from the ACNA site (A and B), differing in texture and amount and type of organic contaminants, were subjected to soil washings by comparing the removal efficiency of water, two synthetic surfactants, sodium dodecylsulphate (SDS) and Triton X-100 (TX100), and a solution of a natural surfactant, a humic acid (HA) at its critical micelle concentration (CMC). The extraction of pollutants by sonication and soxhlet was conducted before and after the soil washings. Soil A was richer in polycyclic aromatic hydrocarbons, whereas soil B had a larger content of thiophenes. Sonication resulted more analytically efficient in the fine-textured soil B. The coarse-textured soil A was extracted with a general equal efficiency also by soxhlet. Clean-up by water was unable to exhaustively remove contaminants from the two soils, whereas all the organic surfactants revealed very similar efficiencies (up to 90%) in the removal of the contaminants from the soils. Hence, the use of solutions of natural HAs appears as a better choice for soil washings of highly polluted soils due to their additional capacity to promote microbial activity, in contrast to synthetic surfactants, for a further natural attenuation in washed soils. - Solutions of natural humic acids appear to be a better choice for washing highly polluted soils

  15. Basic investigations on LCV micelle gel

    International Nuclear Information System (INIS)

    Ebenezer, S B; Rafic, M K; Ravindran, P B

    2013-01-01

    The aim of this study was to investigate the feasibility of using Leuco Crystal Violet (LCV) based micelle gel dosimeter as a quality assurance tool in radiotherapy applications. Basic properties such as absorption coefficient and diffusion of LCV gel phantom over time were evaluated. The gel formulation consisted of 25 mM Trichloroacetic acid, 1mM LCV, 4 mM Triton X-100, 4% gelatin by mass and distilled water. The advantages of using this gel are its tissue equivalence, easy and less preparation time, lower diffusion rate and it can be read with an optical scanner. We were able to reproduce some of the results of Babic et al. The peak absorption was found to be at 600 nm and hence a matrix of yellow LEDs was used as light source. The profiles obtained from projection images confirmed the diffusion of LCV gel after 6 hours of irradiation. Hence the LCV gel phantom should be read before 6 hours post irradiation to get accurate dose information as suggested previously.

  16. Stabilization of α-amylase by using anionic surfactant during the immobilization process

    International Nuclear Information System (INIS)

    El-Batal, A.I.; Atia, K.S.; Eid, M.

    2005-01-01

    This work describes the entrapment of α-amylase into butylacrylate-acrylic acid copolymer (BuA/AAc) using γ irradiation. The effect of an anionic surfactant (AOT), the reuse efficiency, and kinetic behavior of immobilized α-amylase were studied. Covering of α-amylase with bis-(2-ethylhexyl)sulfosuccinate sodium salt (AOT) made the enzyme more stable than the uncovered form. The hydrolytic activity of the pre-coated immobilized α-amylase was increased below the critical micelle concentration (cmc) (10mmol/L). The results showed an increase in the relative activity with increase in the degree of hydration. The pre-coated immobilized α-amylase showed a higher k cat /K m and lower activation energy compared to the free and uncoated-immobilized preparation, respectively. The results suggest that the immobilization of α-amylase is a potentially useful approach for commercial starch hydrolysis in two-phase systems

  17. Red, green, and blue lanthanum phosphate phosphors obtained via surfactant-controlled hydrothermal synthesis

    International Nuclear Information System (INIS)

    Sousa Filho, Paulo C. de; Serra, Osvaldo A.

    2009-01-01

    A new solution route for the obtainment of highly pure luminescent rare-earth orthophosphates in hydrothermal conditions was developed. By starting from soluble precursors (lanthanide tripolyphosphato complexes, i.e. with P 3 O 10 5- as a complexing agent and as an orthophosphate source) and by applying surfactants in a water/toluene medium, the precipitations are confined to reverse micelle structures, thus yielding nanosized and homogeneous orthophosphates. The method was employed to obtain lanthanide-activated lanthanum phosphates, which can be applied as red (LaPO 4 :Eu 3+ ), green (LaPO 4 :Ce 3+ ,Tb 3+ ) and blue (LaPO 4 :Tm 3+ ) phosphors. The produced materials were analyzed by powder X-ray diffractometry, scanning electron microscopy, infrared spectroscopy and luminescence spectroscopy (emission, excitation, lifetimes and chromaticity coordinates).

  18. Stabilization of {alpha}-amylase by using anionic surfactant during the immobilization process

    Energy Technology Data Exchange (ETDEWEB)

    El-Batal, A.I. [National Center for Radiation Research and Technology, P.O. Box 29, Nasr City, Cairo (Egypt); Atia, K.S. [Nuclear Research Center, Radioisotopes Applications Division, Abo-Zable, P.O. Box 13759, Cairo (Egypt)]. E-mail: ks_atia@yahoo.com; Eid, M. [National Center for Radiation Research and Technology, P.O. Box 29, Nasr City, Cairo (Egypt)

    2005-10-01

    This work describes the entrapment of {alpha}-amylase into butylacrylate-acrylic acid copolymer (BuA/AAc) using {gamma} irradiation. The effect of an anionic surfactant (AOT), the reuse efficiency, and kinetic behavior of immobilized {alpha}-amylase were studied. Covering of {alpha}-amylase with bis-(2-ethylhexyl)sulfosuccinate sodium salt (AOT) made the enzyme more stable than the uncovered form. The hydrolytic activity of the pre-coated immobilized {alpha}-amylase was increased below the critical micelle concentration (cmc) (10mmol/L). The results showed an increase in the relative activity with increase in the degree of hydration. The pre-coated immobilized {alpha}-amylase showed a higher k{sub cat}/K{sub m} and lower activation energy compared to the free and uncoated-immobilized preparation, respectively. The results suggest that the immobilization of {alpha}-amylase is a potentially useful approach for commercial starch hydrolysis in two-phase systems.

  19. Stabilization of α-amylase by using anionic surfactant during the immobilization process

    Science.gov (United States)

    El-Batal, A. I.; Atia, K. S.; Eid, M.

    2005-10-01

    This work describes the entrapment of α-amylase into butylacrylate-acrylic acid copolymer (BuA/AAc) using γ irradiation. The effect of an anionic surfactant (AOT), the reuse efficiency, and kinetic behavior of immobilized α-amylase were studied. Covering of α-amylase with bis-(2-ethylhexyl)sulfosuccinate sodium salt (AOT) made the enzyme more stable than the uncovered form. The hydrolytic activity of the pre-coated immobilized α-amylase was increased below the critical micelle concentration (cmc) (10 mmol/L). The results showed an increase in the relative activity with increase in the degree of hydration. The pre-coated immobilized α-amylase showed a higher k/K and lower activation energy compared to the free and uncoated-immobilized preparation, respectively. The results suggest that the immobilization of α-amylase is a potentially useful approach for commercial starch hydrolysis in two-phase systems.

  20. Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method.

    Science.gov (United States)

    Gavrilović, Tamara V; Jovanović, Dragana J; Lojpur, Vesna; Dramićanin, Miroslav D

    2014-02-27

    Synthesis of Eu(3+)- and Er(3+)/Yb(3+)-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu(3+)-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er(3+)/Yb(3+)-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from (2)H11/2 → (2)I15/2 and (4)S3/2 → (4)I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K(-1), which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

  1. Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

    Science.gov (United States)

    Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

    2014-02-01

    Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 --> 2I15/2 and 4S3/2 --> 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K-1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

  2. Stable and biocompatible genipin-inducing interlayer-crosslinked micelles for sustained drug release

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Yu; Zhang, Xiaojin, E-mail: zhangxj@cug.edu.cn [China University of Geosciences, Faculty of Materials Science and Chemistry (China)

    2017-05-15

    To develop the sustained drug release system, here we describe genipin-inducing interlayer-crosslinked micelles crosslinked via Schiff bases between the amines of amphiphilic linear-hyperbranched polymer poly(ethylene glycol)-branched polyethylenimine-poly(ε-caprolactone) (PEG-PEI-PCL) and genipin. The generation of Schiff bases was confirmed by the color changes and UV-Vis absorption spectra of polymeric micelles after adding genipin. The particle size, morphology, stability, in vitro cytotoxicity, drug loading capacity, and in vitro drug release behavior of crosslinked micelles as well as non-crosslinked micelles were characterized. The results indicated that genipin-inducing interlayer-crosslinked micelles had better stability and biocompatibility than non-crosslinked micelles and glutaraldehyde-inducing interlayer-crosslinked micelles. In addition, genipin-inducing interlayer-crosslinked micelles were able to improve drug loading capacity, reduce the initial burst release, and achieve sustained drug release.

  3. Effect of surfactant species and electrophoretic medium composition on the electrophoretic behavior of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis.

    Science.gov (United States)

    Fukai, Nao; Kitagawa, Shinya; Ohtani, Hajime

    2017-07-01

    We have recently demonstrated the separation of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis (NACZE) using a cationic surfactant of cetyltrimethylammonium chloride (CTAC). In this study, eight ionic surfactants were investigated for the separation of four synthetic polymers (polystyrene, polymethylmethacrylates, polybutadiene, and polycarbonate); only three surfactants (CTAC, dimethyldioctadecylammonium bromide, and sodium dodecylsulfate) caused their separation. The order of the interaction between the polymers and the surfactants depended on both the surfactant species and the composition of the electrophoretic medium. Their investigation revealed that the separation is majorly affected by the hydrophobic interactions between the polymers and the ionic surfactants. In addition, the electrophoretic behavior of polycarbonate suggested that electrostatic interaction also affects the selectivity of the polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Controlled Fab installation onto polymeric micelle nanoparticles for tuned bioactivity

    Science.gov (United States)

    Chen, Shaoyi; Florinas, Stelios; Teitgen, Abigail; Xu, Ze-Qi; Gao, Changshou; Wu, Herren; Kataoka, Kazunori; Cabral, Horacio; Christie, R. James

    2017-12-01

    Antibodies and antigen-binding fragments (Fabs) can be used to modify the surface of nanoparticles for enhanced target binding. In our previous work, site-specific conjugation of Fabs to polymeric micelles using conventional methods was limited to approximately 30% efficiency, possibly due to steric hindrance related to macromolecular reactants. Here, we report a new method that enables conjugation of Fabs onto a micelle surface in a controlled manner with up to quantitative conversion of nanoparticle reactive groups. Variation of (i) PEG spacer length in a heterofunctionalized cross-linker and (ii) Fab/polymer feed ratios resulted in production of nanoparticles with a range of Fab densities on the surface up to the theoretical maximum value. The biological impact of variable Fab density was evaluated in vitro with respect to cell uptake and cytotoxicity of a drug-loaded (SN38) targeted polymeric micelle bearing anti-EphA2 Fabs. Fab conjugation increased cell uptake and potency compared with non-targeted micelles, although a Fab density of 60% resulted in decreased uptake and potency of the targeted micelles. Altogether, our findings demonstrate that conjugation strategies can be optimized to allow control of Fab density on the surface of nanoparticles and also that Fab density may need to be optimized for a given cell-surface target to achieve the highest bioactivity.

  5. Light Scattering Characterization of Elastin-Like Polypeptide Trimer Micelles

    Science.gov (United States)

    Tsuper, Ilona; Terrano, Daniel; Maraschky, Adam; Holland, Nolan; Streletzky, Kiril

    The elastin-like polypeptides (ELP) nanoparticles are composed of three-armed star polypeptides connected by a negatively charged foldon. Each of the three arms extending from the foldon domain includes 20 repeats of the (GVGVP) amino acid sequence. The ELP polymer chains are soluble at room temperature and become insoluble at the transition temperature (close to 50 ° C), forming micelles. The size and shape of the micelle are dependent on the temperature and the pH of the solution, and on the concentration of the phosphate buffered saline (PBS). The depolarized dynamic light scattering (DDLS) was employed to study the structure and dynamics of micelles at 62 ° C. The solution was maintained at an approximate pH level of 7.3 - 7.5, while varying PBS concentration. At low salt concentrations (60 mM) displayed an apparent elongation of the micelles evident by a significant VH signal, along with a surge in the apparent Rh. A model of micelle growth (and potential elongation) with increase in salt concentration is considered.

  6. Effect of microfluidization on casein micelle size of bovine milk

    Science.gov (United States)

    Sinaga, H.; Deeth, H.; Bhandari, B.

    2018-02-01

    The properties of milk are likely to be dependent on the casein micelle size, and various processing technologies produce particular change in the average size of casein micelles. The main objective of this study was to manipulate casein micelle size by subjecting milk to microfluidizer. The experiment was performed as a complete block randomised design with three replications. The sample was passed through the microfluidizer at the set pressure of 83, 97, 112 and 126 MPa for one, two, three, four, five and six cycles, except for the 112 MPa. The results showed that microfluidized milk has smaller size by 3% with pressure up to 126 MPa. However, at each pressure, no further reduction was observed after increasing the passed up to 6 cycles. Although the average casein micelle size was similar, elevating pressure resulted in narrower size distribution. In contrast, increasing the number of cycles had little effect on casein micelle distribution. The finding from this study can be applied for future work to characterize the fundamental and functional properties of the treated milk.

  7. Bacterial degradation of emulsified crude oil and the effects of various surfactants

    International Nuclear Information System (INIS)

    Bruheim, P.; Bredholt, H.; Eimhjellen, K.

    1997-01-01

    The effects of surfactants on the oxidation rate of alkanes in crude oil were investigated using a selected bacterial species, Rhodococcus sp., pregrown to various growth stages. Oxidation rates were measured in a three-hour period by Warburg respirometry. Response to emulsified oil was found to be dependent on the physiological state of the bacteria. In the exponential growth phase oxidation rates were negatively affected by surfactant amendment, whereas in the stationary growth phase oxidation rates appear to have been stimulated. The stimulatory effect was attributed to the chemical structure and physico-chemical properties of the surfactants. Surfactants with hydrophilic-lipophilic balance values (HLB) in the intermediate range of 8-12 gave the best values. Neither the commercial dispersants nor the biosurfactants exhibited any stimulative effects. 21 refs., 4 tabs., 1 fig

  8. Production of a biological surfactant

    Directory of Open Access Journals (Sweden)

    N. Gladys Rosero

    2002-01-01

    Full Text Available This paper summarizes the scale up work performed at the Colombian Petroleum Institute on a process to produce at pilot plant level a biosurfactant of the rhamnolipid type. By examination of both the activation conditions of the microorganism and design aspects of the broth, a stable condition was achieved which consistently triggers the production mechanisms and thus it was obtained a significant increment in biosurfactant productivity. The biological surfactant exhibited high efficiency in applications such as hydrocarbon biodegradation in saline environments, corrosion inhibition, and crude oil recovery from storage tank bottom sludges.

  9. Surfactant-assisted dispersion of carbon nanotubes: mechanism of stabilization and biocompatibility of the surfactant

    International Nuclear Information System (INIS)

    Singh, Raman Preet; Jain, Sanyog; Ramarao, Poduri

    2013-01-01

    Nanoparticles (NPs) are thermodynamically unstable system and tend to aggregate to reduce free energy. The aggregation property of NPs results in inhomogeneous exposure of cells to NPs resulting in variable cellular responses. Several types of surfactants are used to stabilize NP dispersions and obtain homogenous dispersions. However, the effects of these surfactants, per se, on cellular responses are not completely known. The present study investigated the application of Pluronic F68 (PF68) for obtaining stable dispersion of NPs using carbon nanotubes as model NPs. PF68-stabilized NP suspensions are stable for long durations and do not show signs of aggregation or settling during storage or after autoclaving. The polyethylene oxide blocks in PF68 provide steric hindrance between adjacent NPs leading to stable NP dispersions. Further, PF68 is biocompatible in nature and does not affect integrity of mitochondria, lysosomes, DNA, and nuclei. Also, PF68 neither induce free radical or cytokine production nor does it interfere with cellular uptake mechanisms. The results of the present study suggest that PF68-assisted dispersion of NPs produced suspensions, which are stable after autoclaving. Further, PF68 does not interfere with normal physiological functions suggesting its application in nanomedicine and nanotoxicity evaluation

  10. Surfactant-assisted dispersion of carbon nanotubes: mechanism of stabilization and biocompatibility of the surfactant

    Science.gov (United States)

    Singh, Raman Preet; Jain, Sanyog; Ramarao, Poduri

    2013-10-01

    Nanoparticles (NPs) are thermodynamically unstable system and tend to aggregate to reduce free energy. The aggregation property of NPs results in inhomogeneous exposure of cells to NPs resulting in variable cellular responses. Several types of surfactants are used to stabilize NP dispersions and obtain homogenous dispersions. However, the effects of these surfactants, per se, on cellular responses are not completely known. The present study investigated the application of Pluronic F68 (PF68) for obtaining stable dispersion of NPs using carbon nanotubes as model NPs. PF68-stabilized NP suspensions are stable for long durations and do not show signs of aggregation or settling during storage or after autoclaving. The polyethylene oxide blocks in PF68 provide steric hindrance between adjacent NPs leading to stable NP dispersions. Further, PF68 is biocompatible in nature and does not affect integrity of mitochondria, lysosomes, DNA, and nuclei. Also, PF68 neither induce free radical or cytokine production nor does it interfere with cellular uptake mechanisms. The results of the present study suggest that PF68-assisted dispersion of NPs produced suspensions, which are stable after autoclaving. Further, PF68 does not interfere with normal physiological functions suggesting its application in nanomedicine and nanotoxicity evaluation.

  11. Surfactant-assisted dispersion of carbon nanotubes: mechanism of stabilization and biocompatibility of the surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Raman Preet, E-mail: ramanpreetsingh@hotmail.com [Evalueserve SEZ (Gurgaon) Pvt. Ltd. (India); Jain, Sanyog [National Institute of Pharmaceutical Education and Research, Centre for Pharmaceutical Nanotechnology, Department of Pharmaceutics (India); Ramarao, Poduri, E-mail: ramaraop@yahoo.com [Central University of Punjab, School of Basic and Applied Sciences (India)

    2013-10-15

    Nanoparticles (NPs) are thermodynamically unstable system and tend to aggregate to reduce free energy. The aggregation property of NPs results in inhomogeneous exposure of cells to NPs resulting in variable cellular responses. Several types of surfactants are used to stabilize NP dispersions and obtain homogenous dispersions. However, the effects of these surfactants, per se, on cellular responses are not completely known. The present study investigated the application of Pluronic F68 (PF68) for obtaining stable dispersion of NPs using carbon nanotubes as model NPs. PF68-stabilized NP suspensions are stable for long durations and do not show signs of aggregation or settling during storage or after autoclaving. The polyethylene oxide blocks in PF68 provide steric hindrance between adjacent NPs leading to stable NP dispersions. Further, PF68 is biocompatible in nature and does not affect integrity of mitochondria, lysosomes, DNA, and nuclei. Also, PF68 neither induce free radical or cytokine production nor does it interfere with cellular uptake mechanisms. The results of the present study suggest that PF68-assisted dispersion of NPs produced suspensions, which are stable after autoclaving. Further, PF68 does not interfere with normal physiological functions suggesting its application in nanomedicine and nanotoxicity evaluation.

  12. Determination of the aggregation number for micelles by isothermal titration calorimetry

    DEFF Research Database (Denmark)

    Olesen, Niels Erik; Holm, Rene; Westh, Peter

    2014-01-01

    Isothermal titration calorimetry (ITC) has previously been applied to estimate the aggregation number (n), Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) of micellization. However, some difficulties of micelle characterization by ITC still remain; most micelles have aggregation numbers...... insight into optimal design of titration protocols for micelle characterization. By applying the new method, the aggregation number of sodium dodecyl sulphate and glycochenodeoxycholate was determined at concentrations around their critical micelle concentration (CMC)...

  13. Hydrolytic Degradation of Poly (ethylene oxide)-block-Polycaprolactone Worm Micelles

    OpenAIRE

    Geng, Yan; Discher, Dennis E.

    2005-01-01

    Spherical micelles and nanoparticles made with degradable polymers have been of great interest for therapeutic application, but degradation induced changes in a spherical morphology can be subtle and mechanism/kinetics appears poorly understood. Here, we report the first preparation of giant and flexible worm micelles self-assembled from degradable copolymer poly (ethylene oxide)-block-polycaprolactone. Such worm micelles spontaneously shorten to generate spherical micelles, triggered by poly...

  14. Interaction between morin and AOT reversed micelles--studies with UV-vis at 25 °C.

    Science.gov (United States)

    Bhattarai, Ajaya; Wilczura-Wachnik, H

    2014-01-30

    The precise measurements of morin absorbance in presence of surfactant/solvent/water systems at 25 °C by UV-vis technique are reported. The surfactant used in presented study was sodium bis(2-ethylhexyl) sulfosuccinate called Aerosol-OT or AOT. The solvents selected were: ethanol, ethylene glycol, and n-decanol. The concentrations of AOT were varied between 0.001 and 0.4 mol/kg. Morin concentration in quvette during UV-vis registration was not equals in all solvent because of its different solubility and absorption intensity depending on the solvent. Water concentration in the studied systems was defined by R parameter according to relation: R=[H2O]/[AOT] and was equal 0, 30 and 40 in ethanol; 0, 10, 20 and 30 in ethylene glycol and 0, 10, 20, 30, and 40 in n-decanol. In presented work a Nernstian distribution of morin between the organic and micellar phases was assumed. The intensity of morin absorbance as a function of AOT concentration was analyzed. Using Non-linear Regression Procedure (NLREG) morin binding constant (K' [mol/kg]), and morin distribution constant (K) between organic phase and AOT micellar phase have been calculated. The experimental results have shown a significant influence of solvent, surfactant and water presence on morin UV-vis spectrum. Calculated data pointed out on different transfer of morin molecules from the organic to micellar phase depending on the solvent. Moreover, results of calculations indicate on competition between morin and water molecules interacting with AOT polar heads. Morin molecules privileged location in AOT reversed micelles strongly depends on the solvent. In case of systems with ethylene glycol as solvent is possible morin molecules location in polar cores of AOT reversed micelles as results of strong interaction between AOT polar heads and morin hydroxyl groups, whereas in case of ethanol and n-decanol morin molecules are located in palisade layer. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Surfactant protein D in newborn infants

    DEFF Research Database (Denmark)

    Dahl, Marianne; Juvonen, Pekka Olavi; Holmskov, Uffe

    2005-01-01

    Surfactant protein D (SP-D) is a collectin that plays an important role in the innate immune system. The role of SP-D in the metabolism of surfactant is as yet quite unclear. The aims of this study were to establish normal values of SP-D in the umbilical cord blood and capillary blood of mature...

  16. Nanoparticle self-assembly in mixtures of phospholipids with styrene/maleic acid copolymers or fluorinated surfactants

    Science.gov (United States)

    Vargas, Carolyn; Arenas, Rodrigo Cuevas; Frotscher, Erik; Keller, Sandro

    2015-12-01

    Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and synthetic membranes and membrane proteins. Considerable efforts are currently underway to replace conventional detergents by milder alternatives such as styrene/maleic acid (SMA) copolymers and fluorinated surfactants. However, these compounds and their nanosized assemblies remain poorly understood as regards their interactions with lipid membranes, particularly, the thermodynamics of membrane partitioning and solubilisation. Using 19F and 31P nuclear magnetic resonance spectroscopy, static and dynamic light scattering, and isothermal titration calorimetry, we have systematically investigated the aggregational state of a zwitterionic bilayer-forming phospholipid upon exposure to an SMA polymer with a styrene/maleic acid ratio of 3 : 1 or to a fluorinated octyl phosphocholine derivative called F6OPC. The lipid interactions of SMA(3 : 1) and F6OPC can be thermodynamically conceptualised within the framework of a three-stage model that treats bilayer vesicles, discoidal or micellar nanostructures, and the aqueous solution as distinct pseudophases. The exceptional solubilising power of SMA(3 : 1) is reflected in very low membrane-saturating and solubilising polymer/lipid molar ratios of 0.10 and 0.15, respectively. Although F6OPC saturates bilayers at an even lower molar ratio of 0.031, this nondetergent does not solubilise lipids even at >1000-fold molar excess, thus highlighting fundamental differences between these two types of mild membrane-mimetic systems. We rationalise these findings in terms of a new classification of surfactants based on bilayer-to-micelle transfer free energies and discuss practical implications for membrane-protein research.Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and

  17. Determination of synthetic phenolic antioxidants in cake by hplc/dad after mixed micelle-mediated cloud point extraction

    International Nuclear Information System (INIS)

    Wang, P.; Liu, C.

    2013-01-01

    A mixed micelle-mediated cloud point extraction (MMCPE) system was developed for the extraction and preconcentration of four synthetic phenolic antioxidants (SPAs) (propyl gallate (PG), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA) and octyl gallate (OG) ) in cake. The mixture of two kinds of non-ionic surfactants polyoxy ethylene nonyl phenyl ether (NP-7) and polyoxy ethylene nonyl phenyl ether (NP-9) was utilized as a suitable micellar medium for preconcentration and extraction of SPAs. The surfactant-rich phase was then analyzed by high performance liquid chromatography-diode array detection (HPLC-DAD). The effect of different parameters such as concentration of surfactants, proportion of NP-7 and NP-9, equilibration time and temperature on the cloud point extraction (CPE) was carefully optimized. Under the studied conditions, four SPAs were successfully separated within 12 min. The relative standard deviations (RSD, n=6) were 1.2-2.0% and the limits of detection (LOD) were 1.5 ng mL-1 for PG, 3.6 ng mL-1 for TBHQ, 2.9 ng mL-1 for BHA, and 0.8 ng mL-1 for OG, respectively. Recoveries of the SPAs in spiked cake samples were in the range of 92% to 99%. The MMCPE method showed potential advantage for the preconcentration of the SPAs, with enrichment factor of 25. Moreover, the method is simple, has high sensitivity, consumes much less solvent, and has significant advantage in extraction efficiency compared to traditional CPE methods. (author)

  18. Biomimetic oral mucin from polymer micelle networks

    Science.gov (United States)

    Authimoolam, Sundar Prasanth

    Mucin networks are formed by the complexation of bottlebrush-like mucin glycoprotein with other small molecule glycoproteins. These glycoproteins create nanoscale strands that then arrange into a nanoporous mesh. These networks play an important role in ensuring surface hydration, lubricity and barrier protection. In order to understand the functional behavior in mucin networks, it is important to decouple their chemical and physical effects responsible for generating the fundamental property-function relationship. To achieve this goal, we propose to develop a synthetic biomimetic mucin using a layer-by-layer (LBL) deposition approach. In this work, a hierarchical 3-dimensional structures resembling natural mucin networks was generated using affinity-based interactions on synthetic and biological surfaces. Unlike conventional polyelectrolyte-based LBL methods, pre-assembled biotin-functionalized filamentous (worm-like) micelles was utilized as the network building block, which from complementary additions of streptavidin generated synthetic networks of desired thickness. The biomimetic nature in those synthetic networks are studied by evaluating its structural and bio-functional properties. Structurally, synthetic networks formed a nanoporous mesh. The networks demonstrated excellent surface hydration property and were able capable of microbial capture. Those functional properties are akin to that of natural mucin networks. Further, the role of synthetic mucin as a drug delivery vehicle, capable of providing localized and tunable release was demonstrated. By incorporating antibacterial curcumin drug loading within synthetic networks, bacterial growth inhibition was also demonstrated. Thus, such bioactive interfaces can serve as a model for independently characterizing mucin network properties and through its role as a drug carrier vehicle it presents exciting future opportunities for localized drug delivery, in regenerative applications and as bio

  19. From micelle supramolecular assemblies in selective solvents to isoporous membranes

    KAUST Repository

    Nunes, Suzana Pereira

    2011-08-16

    The supramolecular assembly of PS-b-P4VP copolymer micelles induced by selective solvent mixtures was used to manufacture isoporous membranes. Micelle order in solution was confirmed by cryo-scanning electron microscopy in casting solutions, leading to ordered pore morphology. When dioxane, a solvent that interacts poorly with the micelle corona, was added to the solution, polymer-polymer segment contact was preferential, increasing the intermicelle contact. Immersion in water gave rise to asymmetric porous membranes with exceptional pore uniformity and high porosity. The introduction of a small number of carbon nanotubes to the casting solution improved the membrane stability and the reversibility of the gate response in the presence of different pH values. © 2011 American Chemical Society.

  20. Artificial Self-Sufficient P450 in Reversed Micelles

    Directory of Open Access Journals (Sweden)

    Teruyuki Nagamune

    2010-04-01

    Full Text Available Cytochrome P450s are heme-containing monooxygenases that require electron transfer proteins for their catalytic activities. They prefer hydrophobic compounds as substrates and it is, therefore, desirable to perform their reactions in non-aqueous media. Reversed micelles can stably encapsulate proteins in nano-scaled water pools in organic solvents. However, in the reversed micellar system, when multiple proteins are involved in a reaction they can be separated into different micelles and it is then difficult to transfer electrons between proteins. We show here that an artificial self-sufficient cytochrome P450, which is an enzymatically crosslinked fusion protein composed of P450 and electron transfer proteins, showed micelle-size dependent catalytic activity in a reversed micellar system. Furthermore, the presence of thermostable alcohol dehydrogenase promoted the P450-catalyzed reaction due to cofactor regeneration.

  1. From micelle supramolecular assemblies in selective solvents to isoporous membranes

    KAUST Repository

    Nunes, Suzana Pereira; Karunakaran, Madhavan; Neelakanda, Pradeep; Behzad, Ali Reza; Hooghan, Bobby; Sougrat, Rachid; He, Haoze; Peinemann, Klaus-Viktor

    2011-01-01

    The supramolecular assembly of PS-b-P4VP copolymer micelles induced by selective solvent mixtures was used to manufacture isoporous membranes. Micelle order in solution was confirmed by cryo-scanning electron microscopy in casting solutions, leading to ordered pore morphology. When dioxane, a solvent that interacts poorly with the micelle corona, was added to the solution, polymer-polymer segment contact was preferential, increasing the intermicelle contact. Immersion in water gave rise to asymmetric porous membranes with exceptional pore uniformity and high porosity. The introduction of a small number of carbon nanotubes to the casting solution improved the membrane stability and the reversibility of the gate response in the presence of different pH values. © 2011 American Chemical Society.

  2. Structural characterization of casein micelles: shape changes during film formation

    International Nuclear Information System (INIS)

    Gebhardt, R; Kulozik, U; Vendrely, C

    2011-01-01

    The objective of this study was to determine the effect of size-fractionation by centrifugation on the film structure of casein micelles. Fractionated casein micelles in solution were asymmetrically distributed with a small distribution width as measured by dynamic light scattering. Films prepared from the size-fractionated samples showed a smooth surface in optical microscopy images and a homogeneous microstructure in atomic force micrographs. The nano- and microstructure of casein films was probed by micro-beam grazing incidence small angle x-ray scattering (μGISAXS). Compared to the solution measurements, the sizes determined in the film were larger and broadly distributed. The measured GISAXS patterns clearly deviate from those simulated for a sphere and suggest a deformation of the casein micelles in the film. (paper)

  3. Charged triblock copolymer self-assembly into charged micelles

    Science.gov (United States)

    Chen, Yingchao; Zhang, Ke; Zhu, Jiahua; Wooley, Karen; Pochan, Darrin; Department of Material Science; Engineering University of Delaware Team; Department of Chemistry Texas A&M University Collaboration

    2011-03-01

    Micelles were formed through the self-assembly of amphiphlic block copolymer poly(acrylic acid)-block-poly(methyl acrylate)-block-polystyrene (PAA-PMA-PS). ~Importantly, the polymer is complexed with diamine molecules in pure THF solution prior to water titration solvent processing-a critical aspect in the control of final micelle geometry. The addition of diamine triggers acid-base complexation ~between the carboxylic acid PAA side chains and amines. ~Remarkably uniform spheres were found to form close-packed patterns when forced into dried films and thin, solvated films when an excess of amine was used in the polymer assembly process. Surface properties and structural features of these hexagonal-packed spherical micelles with charged corona have been explored by various characterization methods including Transmission Electron Microscopy (TEM), cryogenic TEM, z-potential analysis and Dynamic Light Scattering. The forming mechanism for this pattern and morphology changes against external stimulate such as salt will be discussed.

  4. Enzymatically triggered multifunctional delivery system based on hyaluronic acid micelles

    KAUST Repository

    Deng, Lin

    2012-01-01

    Tumor targetability and stimuli responsivity of drug delivery systems (DDS) are key factors in cancer therapy. Implementation of multifunctional DDS can afford targetability and responsivity at the same time. Herein, cholesterol molecules (Ch) were coupled to hyaluronic acid (HA) backbones to afford amphiphilic conjugates that can self-assemble into stable micelles. Doxorubicin (DOX), an anticancer drug, and superparamagnetic iron oxide (SPIO) nanoparticles (NPs), magnetic resonance imaging (MRI) contrast agents, were encapsulated by Ch-HA micelles and were selectively released in the presence of hyaluronidase (Hyals) enzyme. Cytotoxicity and cell uptake studies were done using three cancer cell lines (HeLa, HepG2 and MCF7) and one normal cell line (WI38). Higher Ch-HA micelles uptake was seen in cancer cells versus normal cells. Consequently, DOX release was elevated in cancer cells causing higher cytotoxicity and enhanced cell death. © 2012 The Royal Society of Chemistry.

  5. The effects of exogenous surfactant administration on ventilation-induced inflammation in mouse models of lung injury.

    Science.gov (United States)

    Puntorieri, Valeria; Hiansen, Josh Qua; McCaig, Lynda A; Yao, Li-Juan; Veldhuizen, Ruud A W; Lewis, James F

    2013-11-20

    Mechanical ventilation (MV) is an essential supportive therapy for acute lung injury (ALI); however it can also contribute to systemic inflammation. Since pulmonary surfactant has anti-inflammatory properties, the aim of the study was to investigate the effect of exogenous surfactant administration on ventilation-induced systemic inflammation. Mice were randomized to receive an intra-tracheal instillation of a natural exogenous surfactant preparation (bLES, 50 mg/kg) or no treatment as a control. MV was then performed using the isolated and perfused mouse lung (IPML) set up. This model allowed for lung perfusion during MV. In experiment 1, mice were exposed to mechanical ventilation only (tidal volume =20 mL/kg, 2 hours). In experiment 2, hydrochloric acid or air was instilled intra-tracheally four hours before applying exogenous surfactant and ventilation (tidal volume =5 mL/kg, 2 hours). For both experiments, exogenous surfactant administration led to increased total and functional surfactant in the treated groups compared to the controls. Exogenous surfactant administration in mice exposed to MV only did not affect peak inspiratory pressure (PIP), lung IL-6 levels and the development of perfusate inflammation compared to non-treated controls. Acid injured mice exposed to conventional MV showed elevated PIP, lung IL-6 and protein levels and greater perfusate inflammation compared to air instilled controls. Instillation of exogenous surfactant did not influence the development of lung injury. Moreover, exogenous surfactant was not effective in reducing the concentration of inflammatory cytokines in the perfusate. The data indicates that exogenous surfactant did not mitigate ventilation-induced systemic inflammation in our models. Future studies will focus on altering surfactant composition to improve its immuno-modulating activity.

  6. Surfactant screening of diesel-contaminated soil

    International Nuclear Information System (INIS)

    Peters, R.W.; Shem, L.; Montemagno, C.D.; Lewis, B.

    1991-01-01

    At one installation, approximately 60,000 gal of No. 2 diesel fuel leaked into the subsurface environment, with contamination at depths of 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. The treatability studies focused on four separate phases: (1) leachability studies on the various contaminated soil borings, (2) air stripping studies, (3) bioremediation studies, and (4) surfactant screening/surfactant flooding studies. This paper summarizes the fourth phase of the research program in which 21 surfactants were screened for possible use to mobilize the organics from the contaminated soil prior to bioremediation. Anionic surfactants resulted in the greatest degree of diesel mobilization. The most promising surfactants will be employed on actual contaminated soil samples obtained from the site

  7. The Critical Micelle Concentration of Asphaltenes as Measured by Calorimetry

    DEFF Research Database (Denmark)

    Andersen, Simon Ivar; Christensen, S. D.

    2000-01-01

    Micellization of asphaltenes in solution has been investigated using a micro calorimetric titration procedure (Andersen, S. I.; Birdi, K. S. J Colloid Interface Sci. 1991, 142, 497). The method uses the analysis of heat of dissociation and dilution of asphaltene micelles when a pure solvent (or...... solvent mixture) is titrated with a solution of asphaltene in the same solvent. The asphaltene concentration of the injected solution is at a level above the critical micelle concentration (CMC). In the present paper the procedure is applied in investigation of asphaltenes as well as subfractions...

  8. Core-Shell-Corona Micelles with a Responsive Shell.

    Science.gov (United States)

    Gohy, Jean-François; Willet, Nicolas; Varshney, Sunil; Zhang, Jian-Xin; Jérôme, Robert

    2001-09-03

    A reactor for the synthesis of gold nanoparticles is one of the uses of a poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) triblock copolymer (PS-b-P2VP-b-PEO) which forms core-shell-corona micelles in water. Very low polydispersity spherical micelles are observed that consist of a PS core surrounded by a pH-sensitive P2VP shell and a corona of PEO chains end-capped by a hydroxyl group. The corona can act as a site for attaching responsive or sensing molecules. © 2001 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

  9. Fluorescent supramolecular micelles for imaging-guided cancer therapy

    Science.gov (United States)

    Sun, Mengmeng; Yin, Wenyan; Dong, Xinghua; Yang, Wantai; Zhao, Yuliang; Yin, Meizhen

    2016-02-01

    A novel smart fluorescent drug delivery system composed of a perylene diimide (PDI) core and block copolymer poly(d,l-lactide)-b-poly(ethyl ethylene phosphate) is developed and named as PDI-star-(PLA-b-PEEP)8. The biodegradable PDI-star-(PLA-b-PEEP)8 is a unimolecular micelle and can self-assemble into supramolecular micelles, called as fluorescent supramolecular micelles (FSMs), in aqueous media. An insoluble drug camptothecin (CPT) can be effectively loaded into the FSMs and exhibits pH-responsive release. Moreover, the FSMs with good biocompatibility can also be employed as a remarkable fluorescent probe for cell labelling because the maximum emission of PDI is beneficial for bio-imaging. The flow cytometry and confocal laser scanning microscopy analysis demonstrate that the micelles are easily endocytosed by cancer cells. In vitro and in vivo tumor growth-inhibitory studies reveal a better therapeutic effect of FSMs after CPT encapsulation when compared with the free CPT drug. The multifunctional FSM nanomedicine platform as a nanovehicle has great potential for fluorescence imaging-guided cancer therapy.A novel smart fluorescent drug delivery system composed of a perylene diimide (PDI) core and block copolymer poly(d,l-lactide)-b-poly(ethyl ethylene phosphate) is developed and named as PDI-star-(PLA-b-PEEP)8. The biodegradable PDI-star-(PLA-b-PEEP)8 is a unimolecular micelle and can self-assemble into supramolecular micelles, called as fluorescent supramolecular micelles (FSMs), in aqueous media. An insoluble drug camptothecin (CPT) can be effectively loaded into the FSMs and exhibits pH-responsive release. Moreover, the FSMs with good biocompatibility can also be employed as a remarkable fluorescent probe for cell labelling because the maximum emission of PDI is beneficial for bio-imaging. The flow cytometry and confocal laser scanning microscopy analysis demonstrate that the micelles are easily endocytosed by cancer cells. In vitro and in vivo tumor growth

  10. Micelle-Assisted Synthesis of Al2O3·CaO Nanocatalyst: Optical Properties and Their Applications in Photodegradation of 2,4,6-Trinitrophenol

    Directory of Open Access Journals (Sweden)

    Ayesha Imtiaz

    2013-01-01

    Full Text Available Calcium oxide (CaO nanoparticles are known to exhibit unique property due to their high adsorption capacity and good catalytic activity. In this work the CaO nanocatalysts were prepared by hydrothermal method using anionic surfactant, sodium dodecyl sulphate (SDS, as a templating agent. The as-synthesized nanocatalysts were further used as substrate for the synthesis of alumina doped calcium oxide (Al2O3·CaO nanocatalysts via deposition-precipitation method at the isoelectric point of CaO. The Al2O3·CaO nanocatalysts were characterized by FTIR, XRD, TGA, TEM, and FESEM techniques. The catalytic efficiencies of these nanocatalysts were studied for the photodegradation of 2,4,6-trinitrophenol (2,4,6-TNP, which is an industrial pollutant, spectrophotometrically. The effect of surfactant and temperature on size of nanocatalysts was also studied. The smallest particle size and highest percentage of degradation were observed at critical micelle concentration of the surfactant. The direct optical band gap of the Al2O3·CaO nanocatalyst was found as 3.3 eV.

  11. Role of Marangoni stress during breakup of surfactant-covered liquid threads: Reduced rates of thinning and microthread cascades

    Science.gov (United States)

    Kamat, Pritish M.; Wagoner, Brayden W.; Thete, Sumeet S.; Basaran, Osman A.

    2018-04-01

    Adsorption onto and lowering of surface tension σ of fluid interfaces by surfactants is exploited in drop formation (e.g., inkjet printing) where a thinning liquid thread (radius h ) connects an about-to-form drop to the liquid that remains hanging from the nozzle when the former falls from it. Surfactants can affect thread pinch-off in two ways: first, by lowering σ , they lower capillary pressure (σ /h ), and second, as surfactant concentration along the interface can be nonuniform, they cause the interface to be subjected to a surface tension gradient or Marangoni stress. Recent studies show that the location where the thread breaks is devoid of surfactant, and others assert that the influence of Marangoni stress on pinch-off is negligible. We demonstrate by simulations and experiments that surfactants play a major role in drop formation and that Marangoni stresses acting near but not at the pinch point give rise to reduced rates of thread thinning and formation of multiple microthreads that distinguish pinch-off of surfactant-covered threads from surfactant-free ones. Thinning at finite Reynolds and Peclet numbers, Re and Pe, is shown to exhibit intermediate scaling regimes that have heretofore only been observed during pinch-off of threads undergoing creeping flow (Re=0 ) while convection of surfactant is weak compared to its diffusion (Pe<1 ).

  12. Binding of chloroquine to ionic micelles: Effect of pH and micellar surface charge

    Energy Technology Data Exchange (ETDEWEB)

    Souza Santos, Marcela de, E-mail: marcelafarmausp77@gmail.com [Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Avenida do Café, s/n, Ribeirão Preto, São Paulo 14040-903 (Brazil); Perpétua Freire de Morais Del Lama, Maria, E-mail: mpemdel@fcfrp.usp.br [Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Avenida do Café, s/n, Ribeirão Preto, São Paulo 14040-903 (Brazil); Instituto Nacional de Ciência e Tecnologia de Bioanalítica, Departamento de Química Analítica, Universidade Estadual de Campinas, Cidade Universitária Zeferino Vaz, s/n, Campinas, São Paulo 13083-970 (Brazil); Siuiti Ito, Amando, E-mail: amandosi@ffclrp.usp.br [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes, 3900, Ribeirão Preto, São Paulo 14040-901 (Brazil); and others

    2014-03-15

    The pharmacological action of chloroquine relies on its ability to cross biological membranes in order to accumulate inside lysosomes. The present work aimed at understanding the basis for the interaction between different chloroquine species and ionic micelles of opposite charges, the latter used as a simple membrane model. The sensitivity of absorbance and fluorescence of chloroquine to changes in its local environment was used to probe its interaction with cetyltrimethylammonium micelles presenting bromide (CTAB) and sulfate (CTAS) as counterions, in addition to dodecyl sulfate micelles bearing sodium (SDS) and tetramethylammonium (TMADS) counterions. Counterion exchange was shown to have little effect on drug–micelle interaction. Chloroquine first dissociation constant (pKa{sub 1}) shifted to opposite directions when anionic and cationic micelles were compared. Chloroquine binding constants (K{sub b}) revealed that electrostatic forces mediate charged drug–micelle association, whereas hydrophobic interactions allowed neutral chloroquine to associate with anionic and cationic micelles. Fluorescence quenching studies indicated that monoprotonated chloroquine is inserted deeper into the micelle surface of anionic micelles than its neutral form, the latter being less exposed to the aqueous phase when associated with cationic over anionic assemblies. The findings provide further evidence that chloroquine–micelle interaction is driven by a tight interplay between the drug form and the micellar surface charge, which can have a major effect on the drug biological activity. -- Highlights: • Chloroquine (CQ) pKa{sub 1} increased for SDS micelles and decreased for CTAB micelles. • CQ is solubilized to the surface of both CTAB and SDS micelles. • Monoprotonated CQ is buried deeper into SDS micelles than neutral CQ. • Neutral CQ is less exposed to aqueous phase in CTAB over SDS micelles. • Local pH and micellar surface charge mediate interaction of CQ with

  13. Degradation of soil-sorbed trichloroethylene by stabilized zero valent iron nanoparticles: Effects of sorption, surfactants, and natural organic matter

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Man [Auburn University, Auburn, Alabama; He, Feng [ORNL; Zhao, Dongye [Auburn University, Auburn, Alabama; Hao, Xiaodi [Beijing University of Civil Engineering and Architecture

    2011-01-01

    Zero valent iron (ZVI) nanoparticles have been studied extensively for degradation of chlorinated solvents in the aqueous phase, and have been tested for in-situ remediation of contaminated soil and groundwater. However, little is known about its effectiveness for degrading soil-sorbed contaminants. This work studied reductive dechlorination of trichloroethylene (TCE) sorbed in two model soils (a potting soil and Smith Farm soil) using carboxymethyl cellulose (CMC) stabilized Fe-Pd bimetallic nanoparticles. Effects of sorption, surfactants and dissolved organic matter (DOC) were determined through batch kinetic experiments. While the nanoparticles can effectively degrade soil-sorbed TCE, the TCE degradation rate was strongly limited by desorption kinetics, especially for the potting soil which has a higher organic matter content of 8.2%. Under otherwise identical conditions, {approx}44% of TCE sorbed in the potting soil was degraded in 30 h, compared to {approx}82% for Smith Farm soil (organic matter content = 0.7%). DOC from the potting soil was found to inhibit TCE degradation. The presence of the extracted SOM at 40 ppm and 350 ppm as TOC reduced the degradation rate by 34% and 67%, respectively. Four prototype surfactants were tested for their effects on TCE desorption and degradation rates, including two anionic surfactants known as SDS (sodium dodecyl sulfate) and SDBS (sodium dodecyl benzene sulfonate), a cationic surfactant hexadecyltrimethylammonium (HDTMA) bromide, and a non-ionic surfactant Tween 80. All four surfactants were observed to enhance TCE desorption at concentrations below or above the critical micelle concentration (cmc), with the anionic surfactant SDS being most effective. Based on the pseudo-first-order reaction rate law, the presence of 1 x cmc SDS increased the reaction rate by a factor of 2.5 when the nanoparticles were used for degrading TCE in a water solution. SDS was effective for enhancing degradation of TCE sorbed in Smith Farm

  14. Spectroscopic characterization approach to study surfactants effect on ZnO 2 nanoparticles synthesis by laser ablation process

    Science.gov (United States)

    Drmosh, Q. A.; Gondal, M. A.; Yamani, Z. H.; Saleh, T. A.

    2010-05-01

    Zinc peroxide nanoparticles having grain size less than 5 nm were synthesized using pulsed laser ablation in aqueous solution in the presence of different surfactants and solid zinc target in 3% H 2O 2. The effect of surfactants on the optical and structure of ZnO 2 was studied by applying different spectroscopic techniques. Structural properties and grain size of the synthesized nanoparticles were studied using XRD method. The presence of the cubic phase of zinc peroxide in all samples was confirmed with XRD, and the grain sizes were 4.7, 3.7, 3.3 and 2.8 nm in pure H 2O 2, and H 2O 2 mixed with SDS, CTAB and OGM respectively. For optical characterization, FTIR transmittance spectra of ZnO 2 nanoparticles prepared with and without surfactants show a characteristic ZnO 2 absorption at 435-445 cm -1. FTIR spectrum revealed that the adsorbed surfactants on zinc peroxide disappeared in case of CTAB and OGM while it appears in case of SDS. This could be due to high critical micelles SDS concentration comparing with others which is attributed to the adsorption anionic nature of this surfactant. Both FTIR and UV-vis spectra show a red shift in the presence of SDS and blue shift in the presence of CTAB and OGM. The blue shift in the absorption edge indicates the quantum confinement property of nanoparticles. The zinc peroxide nanoparticles prepared in additives-free media was also characterized by Raman spectra which show the characteristic peaks at 830-840 and 420-440 cm -1.

  15. Spectroscopic characterization approach to study surfactants effect on ZnO{sub 2} nanoparticles synthesis by laser ablation process

    Energy Technology Data Exchange (ETDEWEB)

    Drmosh, Q.A. [Laser Research Group, Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Center of Excellence in Nanotechnology (CENT), King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Gondal, M.A., E-mail: magondal@kfupm.edu.sa [Laser Research Group, Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Center of Excellence in Nanotechnology (CENT), King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Yamani, Z.H. [Laser Research Group, Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Center of Excellence in Nanotechnology (CENT), King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Saleh, T.A. [Center of Excellence in Nanotechnology (CENT), King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Chemistry Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2010-05-01

    Zinc peroxide nanoparticles having grain size less than 5 nm were synthesized using pulsed laser ablation in aqueous solution in the presence of different surfactants and solid zinc target in 3% H{sub 2}O{sub 2}. The effect of surfactants on the optical and structure of ZnO{sub 2} was studied by applying different spectroscopic techniques. Structural properties and grain size of the synthesized nanoparticles were studied using XRD method. The presence of the cubic phase of zinc peroxide in all samples was confirmed with XRD, and the grain sizes were 4.7, 3.7, 3.3 and 2.8 nm in pure H{sub 2}O{sub 2}, and H{sub 2}O{sub 2} mixed with SDS, CTAB and OGM respectively. For optical characterization, FTIR transmittance spectra of ZnO{sub 2} nanoparticles prepared with and without surfactants show a characteristic ZnO{sub 2} absorption at 435-445 cm{sup -1}. FTIR spectrum revealed that the adsorbed surfactants on zinc peroxide disappeared in case of CTAB and OGM while it appears in case of SDS. This could be due to high critical micelles SDS concentration comparing with others which is attributed to the adsorption anionic nature of this surfactant. Both FTIR and UV-vis spectra show a red shift in the presence of SDS and blue shift in the presence of CTAB and OGM. The blue shift in the absorption edge indicates the quantum confinement property of nanoparticles. The zinc peroxide nanoparticles prepared in additives-free media was also characterized by Raman spectra which show the characteristic peaks at 830-840 and 420-440 cm{sup -1}.

  16. Spectroscopic characterization approach to study surfactants effect on ZnO2 nanoparticles synthesis by laser ablation process

    International Nuclear Information System (INIS)

    Drmosh, Q.A.; Gondal, M.A.; Yamani, Z.H.; Saleh, T.A.

    2010-01-01

    Zinc peroxide nanoparticles having grain size less than 5 nm were synthesized using pulsed laser ablation in aqueous solution in the presence of different surfactants and solid zinc target in 3% H 2 O 2 . The effect of surfactants on the optical and structure of ZnO 2 was studied by applying different spectroscopic techniques. Structural properties and grain size of the synthesized nanoparticles were studied using XRD method. The presence of the cubic phase of zinc peroxide in all samples was confirmed with XRD, and the grain sizes were 4.7, 3.7, 3.3 and 2.8 nm in pure H 2 O 2 , and H 2 O 2 mixed with SDS, CTAB and OGM respectively. For optical characterization, FTIR transmittance spectra of ZnO 2 nanoparticles prepared with and without surfactants show a characteristic ZnO 2 absorption at 435-445 cm -1 . FTIR spectrum revealed that the adsorbed surfactants on zinc peroxide disappeared in case of CTAB and OGM while it appears in case of SDS. This could be due to high critical micelles SDS concentration comparing with others which is attributed to the adsorption anionic nature of this surfactant. Both FTIR and UV-vis spectra show a red shift in the presence of SDS and blue shift in the presence of CTAB and OGM. The blue shift in the absorption edge indicates the quantum confinement property of nanoparticles. The zinc peroxide nanoparticles prepared in additives-free media was also characterized by Raman spectra which show the characteristic peaks at 830-840 and 420-440 cm -1 .

  17. One-step synthesis, wettability and foaming properties of high-performance non-ionic hydro-fluorocarbon hybrid surfactants

    Science.gov (United States)

    Peng, Ying-ying; Lu, Feng; Tong, Qing-Xiao

    2018-03-01

    In this work, a series of non-ionic hydro-fluorocarbon hybrid surfactants (C9F19CONH(CH2)3N(CmH2m+1)2, abbreviated as C9F19AM (m = 1), C9F19AE (m = 2) and C9F19AB (m = 4) were easily synthesized by one-step reaction and characterized by 1HNMR, 19FNMR and MS spectroscopy. Unlike conventional non-ionic surfactants (most hydrophilic units consisted of hydroxy or ether groups), their hydrophilic groups were composed of amide group, an eco-friendly unit. The surface activity, wettability, thermal stability and foaming performance were investigated. The results showed that the C9F19AE (C9F19CONH(CH2)3N[CH2CH3]2) had superior surface and interface activities, which could reduce the surface tension of water down to 15.37 mN/m and the interfacial tension (cyclohexane/water/surfactants) to 5.8 mN/m with a low cmc (critical micelle concentration) of 0.12 mmol/L. Through the calculation of Amin (the minimum area occupied per-surfactant molecule), we speculated this higher surface activity was related to the compatibility between hydrocarbon and fluorocarbon chains. When used as wetting and foaming agents, the C9F19AE also outperformed great advantages over conventional non-ionic fluorocarbon and hydrocarbon surfactants, which could decrease the contact angle of water on PTFE plate from 107.7° to 3.6°, and increase the foam integrated value F to 536 500 ± 3066.5 mL s. Moreover, the decomposition temperature (Td) of C9F19AE could reach up to 173 °C. This work demonstrates a valuable strategy to develop a kind of high-efficiency foaming agent via facile synthesis.

  18. Surfactant replacement therapy--economic impact.

    Science.gov (United States)

    Pejaver, R K; al Hifzi, I; Aldussari, S

    2001-06-01

    Surfactant replacement is an effective treatment for neonatal respiratory distress syndrome. (RDS). As widespread use of surfactant is becoming a reality, it is important to assess the economic implications of this new form of therapy. A comparison study was carried out at the Neonatal Intensive Care Unit (NICU) of Northwest Armed Forces Hospital, Saudi Arabia. Among 75 infants who received surfactant for RDS and similar number who were managed during time period just before the surfactant was available, but by set criteria would have made them eligible for surfactant. All other management modalities except surfactant were the same for all these babies. Based on the intensity of monitoring and nursing care required by the baby, the level of care was divided as: Level IIIA, IIIB, Level II, Level I. The cost per day per bed for each level was calculated, taking into account the use of hospital immovable equipment, personal salaries of nursing, medical, ancillary staff, overheads and maintenance, depreciation and replacement costs. Medications used, procedures done, TPN, oxygen, were all added to individual patient's total expenditure. 75 infants in the Surfactant group had 62 survivors. They spent a total of 4300 days in hospital. (av 69.35) Out of which 970 d (av 15.65 per patient) were ventilated days. There were 56 survivors in the non-surfactant group of 75. They had spent a total of 5023 days in the hospital (av 89.69/patient) out of which 1490 were ventilated days (av 26.60 d). Including the cost of surfactant (two doses), cost of hospital stay for each infant taking the average figures of stay would be SR 118, 009.75 per surfactant treated baby and SR 164, 070.70 per non-surfactant treated baby. The difference of 46,061 SR is 39.03% more in non-surfactant group. One Saudi rial = 8 Rs (approx at the time study was carried out.) Medical care cost varies from place to place. However, it is definitely cost-effective where surfactant is concerned. Quality adjusted

  19. Rhamnolipids--next generation surfactants?

    Science.gov (United States)

    Müller, Markus Michael; Kügler, Johannes H; Henkel, Marius; Gerlitzki, Melanie; Hörmann, Barbara; Pöhnlein, Martin; Syldatk, Christoph; Hausmann, Rudolf

    2012-12-31

    The demand for bio-based processes and materials in the petrochemical industry has significantly increased during the last decade because of the expected running out of petroleum. This trend can be ascribed to three main causes: (1) the increased use of renewable resources for chemical synthesis of already established product classes, (2) the replacement of chemical synthesis of already established product classes by new biotechnological processes based on renewable resources, and (3) the biotechnological production of new molecules with new features or better performances than already established comparable chemically synthesized products. All three approaches are currently being pursued for surfactant production. Biosurfactants are a very promising and interesting substance class because they are based on renewable resources, sustainable, and biologically degradable. Alkyl polyglycosides are chemically synthesized biosurfactants established on the surfactant market. The first microbiological biosurfactants on the market were sophorolipids. Of all currently known biosurfactants, rhamnolipids have the highest potential for becoming the next generation of biosurfactants introduced on the market. Although the metabolic pathways and genetic regulation of biosynthesis are known qualitatively, the quantitative understanding relevant for bioreactor cultivation is still missing. Additionally, high product titers have been exclusively described with vegetable oil as sole carbon source in combination with Pseudomonas aeruginosa strains. Competitive productivity is still out of reach for heterologous hosts or non-pathogenic natural producer strains. Thus, on the one hand there is a need to gain a deeper understanding of the regulation of rhamnolipid production on process and cellular level during bioreactor cultivations. On the other hand, there is a need for metabolizable renewable substrates, which do not compete with food and feed. A sustainable bioeconomy approach should

  20. Static structure factor of polymerlike micelles: Overall dimension, flexibility, and local properties of lecithin reverse micelles in deuterated isooctane

    DEFF Research Database (Denmark)

    Jerke, G.; Pedersen, J.S.; Egelhaaf, S.U.

    1997-01-01

    We report a systematic investigation of the static structure factor S(q,c) of polymerlike reverse micelles formed by soybean lecithin and trace amounts of water in deuterated isooctane using small-angle neutron scattering and static light scattering. The experimental data for different concentrat......We report a systematic investigation of the static structure factor S(q,c) of polymerlike reverse micelles formed by soybean lecithin and trace amounts of water in deuterated isooctane using small-angle neutron scattering and static light scattering. The experimental data for different...

  1. Electrostatic Interactions Govern "Odd/Even" Effects in Water-Induced Gemini Surfactant Self-Assembly.

    Science.gov (United States)

    Mantha, Sriteja; McDaniel, Jesse G; Perroni, Dominic V; Mahanthappa, Mahesh K; Yethiraj, Arun

    2017-01-26

    Gemini surfactants comprise two single-tailed surfactants connected by a linker at or near the hydrophilic headgroup. They display a variety of water-concentration-dependent lyotropic liquid crystal morphologies that are sensitive to surfactant molecular structure and the nature of the headgroups and counterions. Recently, an interesting dependence of the aqueous-phase behavior on the length of the linker has been discovered; odd-numbered linker length surfactants exhibit characteristically different phase diagrams than even-numbered linker surfactants. In this work, we investigate this "odd/even effect" using computer simulations, focusing on experimentally studied gemini dicarboxylates with Na + counterions, seven nonterminal carbon atoms in the tails, and either three, four, five, or six carbon atoms in the linker (denoted Na-73, Na-74, Na-75, and Na-76, respectively). We find that the relative electrostatic repulsion between headgroups in the different morphologies is correlated with the qualitative features of the experimental phase diagrams, predicting destabilization of hexagonal phases as the cylinders pack close together at low water content. Significant differences in the relative headgroup orientations of Na-74 and Na-76 compared to those of Na-73 and Na-75 surfactants lead to differences in linker-linker packing and long-range headgroup-headgroup electrostatic repulsion, which affects the delicate electrostatic balance between the hexagonal and gyroid phases. Much of the fundamental insight presented in this work is enabled by the ability to computationally construct and analyze metastable phases that are not observable in experiments.

  2. A Molecular Dynamics Study of Single-Walled Carbon Nanotubes (SWCNTs) Dispersed in Bile Salt Surfactants

    Science.gov (United States)

    Phelan, Frederick, Jr.; Sun, Huai

    2014-03-01

    Single-walled carbon nanotubes (SWNCTs) are materials with structural, electronic and optical properties that make them attractive for a myriad of advanced technology applications. A practical barrier to their use is that SWCNT synthesis techniques produce heterogeneous mixtures of varying lengths and chirality, whereas applications generally require tubes with narrow size distributions and individual type. Most separation techniques currently in use to obtain monodisperse tube fractions rely on dispersion of these materials in aqueous solution using surfactants. The dispersion process results in a mixture of colloidal structures in which individual tubes are dispersed and contained in a surfactant shell. Understanding the structure and properties of the SWCNT-surfactant complex at the molecular level, and how this is affected by chirality, is key to understanding and improving separations processes. In this study, we use molecular dynamics (MD) simulations to study the structure and properties of SWCNT-surfactant colloidal complexes. We tested a number of methods and protocols in order to build an accurate model for simulating SWCNT systems for a variety of bile salt surfactants as well as anionic co-surfactants, components that are widely used and important in experimental separation studies at NIST. The custom force field parameters used here will be stored in WebFF, a Web-hosted smart force-field repository for polymeric and organic materials being developed at NIST for the Materials Genome Initiative.

  3. Surfactants tailored by the class Actinobacteria

    Directory of Open Access Journals (Sweden)

    Johannes H Kügler

    2015-03-01

    Full Text Available Gloablly, the drive towards the establishment of a bio-based economy has resulted in an increased need for bio-based applications. This, in turn, has served as a driving force for the discovery and application of novel biosurfactants. The class Actinobacteria represents a vast group of microorganisms with the ability to produce a diverse range of secondary metabolites, including surfactants. Understanding the extensive nature of the biosurfactants produced by actinobacterial strains can assist in finding novel biosurfactants with new potential applications. This review therefore presents a comprehensive overview of the knowledge available on actinobacterial surfactants, the chemical structures that have been completely or partly elucidated, as well as the identity of the biosurfactant-producing strains. Producer strains of not yet elucidated compounds are discussed, as well as the original habitats of all the producer strains, which seems to indicate that biosurfactant production is environmentally driven. Methodology applied in the isolation, purification and structural elucidation of the different types of surface active compounds, as well as surfactant activity tests, are also discussed. Overall, actinobacterial surfactants can be summarized to include the dominantly occurring trehalose-comprising surfactants, other non-trehalose containing glycolipids, lipopeptides and the more rare actinobacterial surfactants. The lack of structural information on a large proportion of actinobacterial surfactants should be considered as a driving force to further explore the abundance and diversity of these compounds. This would allow for a better understanding of actinobacterial surface active compounds and their potential for biotechnological application.