WorldWideScience

Sample records for dodecylphosphocholine micelles sodium

  1. Modeling the Interaction of Dodecylphosphocholine Micelles with the Anticoccidial Peptide PW2 Guided by NMR Data

    Directory of Open Access Journals (Sweden)

    Francisco Gomes-Neto

    2013-08-01

    Full Text Available Antimicrobial peptides are highly dynamic entities that acquire structure upon binding to a membrane interface. To better understand the structure and the mechanism for the molecular recognition of dodecylphosphocholine (DPC micelles by the anticoccidial peptide PW2, we performed molecular dynamics (MD simulations guided by NMR experimental data, focusing on strategies to explore the transient nature of micelles, which rearrange on a millisecond to second timescale. We simulated the association of PW2 with a pre-built DPC micelle and with free-DPC molecules that spontaneously forms micelles in the presence of the peptide along the simulation. The simulation with spontaneous micelle formation provided the adequate environment which replicated the experimental data. The unrestrained MD simulations reproduced the NMR structure for the entire 100 ns MD simulation time. Hidden discrete conformational states could be described. Coulomb interactions are important for initial approximation and hydrogen bonds for anchoring the aromatic region at the interface, being essential for the stabilization of the interaction. Arg9 is strongly attached with phosphate. We observed a helix elongation process stabilized by the intermolecular peptide-micelle association. Full association that mimics the experimental data only happens after complete micelle re-association. Fast micelle dynamics without dissociation of surfactants leads to only superficial binding.

  2. Oligomeric structure of a cathelicidin antimicrobial peptide in dodecylphosphocholine micelle determined by NMR spectroscopy.

    Science.gov (United States)

    Saravanan, Rathi; Bhattacharjya, Surajit

    2011-01-01

    The broad spectrum of antibacterial activities of host defense cationic antimicrobial peptides (AMPs) arises from their ability to perturb membrane integrity of the microbes. The mechanisms are often thought to require assembly of AMPs on the membrane surface to form pores. However, three dimensional structures in the oligomeric form of AMPs in the context of lipid membranes are largely limited. Here, we demonstrate that a 22-residue antimicrobial peptide, termed VK22, derived from fowlicidin-1, a cathelicidin family of AMP from chicken oligomerizes into a predominantly tetrameric state in zwitterionic dodecylphosphocholine (DPC) micelles. An ensemble of NMR structures of VK22 determined in 200mM perdeuterated DPC, from 755 NOE constrains including 19 inter-helical NOEs, had revealed an assembly of four helices arranged in anti-parallel fashion. Hydrogen bonds, C(α)H-O=C types, and van der Waals interactions among the helical sub-units appear to be involved in the stabilization of the quaternary structures. The central region of the barrel shaped tetrameric bundle is non-polar with clusters of aromatic residues, whereas all the cationic residues are positioned at the termini. Paramagnetic spin labeled NMR experiments indicated that the tetrameric structure is embedded into micelles such that the non-polar region located inside the lipid acyl chains. Structure and micelle localization of a monomeric version, obtained from substitution of two Tyr residues with Ala, of the peptide is also compared. The mutated peptide VK22AA has been found be localized at the surface of the micelles. The tetrameric structure of VK22 delineates a small water pore that can be larger in the higher order oligomers. As these results provide structural insights, at atomic resolution, into the oligomeric states of a helical AMP in lipid environment, the structural details may be further utilized for the design of novel self-assembled membrane protein mimics.

  3. Solution structure of the antimicrobial peptide ranalexin and a study of its interaction with perdeuterated dodecylphosphocholine micelles.

    Science.gov (United States)

    Vignal, E; Chavanieu, A; Roch, P; Chiche, L; Grassy, G; Calas, B; Aumelas, A

    1998-04-01

    Ranalexin, a 20-residue peptide isolated from the skin of the bullfrog Rana catesbeiana displays antimicrobial activity. This peptide contains two cysteine residues in positions 14 and 20 linked by a disulphide bridge. Ranalexin was chemically synthesised and close antimicrobial activities were measured for the reduced and oxidised forms. The solution structure of ranalexin was determined by using circular dichroism, proton NMR spectroscopy and molecular modelling techniques. The reduced and oxidised forms of ranalexin are mainly unstructured in water but display an alpha-helical structure spanning residues 8-15 and 8-17, respectively, in a trifluoroethanol/water mixture (3:7, by vol.). Ranalexin was found to interact with micelles of dodecylphosphocholine and to adopt a similar helical structure. Moreover, slow-exchanging amide protons located on the same side of the helix suggest that the hydrophobic face of the helix lies on the micelle surface. Hydrophobic residues of the poorly structured N-terminal part which are important for the biological activity are also involved in the interaction with micelles. Taken together, the results suggest that the disulphide bond does not strongly affect either the conformation or the antimicrobial activity of ranalexin.

  4. Molecular dynamics simulations of the helical antimicrobial peptide ovispirin-1 in a zwitterionic dodecylphosphocholine micelle

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Kaznessis, Yiannis N

    2005-01-01

    We have carried out a 40-ns all-atom molecular dynamics simulation of the helical antimicrobial peptide ovispirin-1 (OVIS) in a zwitterionic diphosphocholine (DPC) micelle. The DPC micelle serves as an economical and effective model for a cellular membrane owing to the presence of a choline...... headgroup, which resembles those of membrane phospholipids. OVIS, which was initially placed along a micelle diameter, diffuses out to the water-DPC interface, and the simulation stabilizes to an interface-bound steady state in 40 ns. The helical content of the peptide marginally increases in the process...... in the micellar core and the polar side chains protruding into the aqueous phase. There is overwhelming evidence that points to the significant and indispensable participation of hydrophobic residues in binding to the zwitterionic interface. The simulation starts with a conformation that is unbiased toward...

  5. CHARMM-GUI micelle builder for pure/mixed micelle and protein/micelle complex systems.

    Science.gov (United States)

    Cheng, Xi; Jo, Sunhwan; Lee, Hui Sun; Klauda, Jeffery B; Im, Wonpil

    2013-08-26

    Micelle Builder in CHARMM-GUI, http://www.charmm-gui.org/input/micelle , is a web-based graphical user interface to build pure/mixed micelle and protein/micelle complex systems for molecular dynamics (MD) simulation. The robustness of Micelle Builder is tested by simulating four detergent-only homogeneous micelles of DHPC (dihexanoylphosphatidylcholine), DPC (dodecylphosphocholine), TPC (tetradecylphosphocholine), and SDS (sodium dodecyl sulfate) and comparing the calculated micelle properties with experiments and previous simulations. As a representative protein/micelle model, Pf1 coat protein is modeled and simulated in DHPC micelles with three different numbers of DHPC molecules. While the number of DHPC molecules in direct contact with Pf1 protein converges during the simulation, distinct behavior and geometry of micelles lead to different protein conformations in comparison to that in bilayers. It is our hope that CHARMM-GUI Micelle Builder can be used for simulation studies of various protein/micelle systems to better understand the protein structure and dynamics in micelles as well as distribution of detergents and their dynamics around proteins.

  6. How can a beta-sheet peptide be both a potent antimicrobial and harmfully toxic? Molecular dynamics simulations of protegrin-1 in micelles

    DEFF Research Database (Denmark)

    Langham, Allison A; Khandelia, Himanshu; Kaznessis, Yiannis N

    2006-01-01

    In this work, the naturally occurring beta-hairpin antimicrobial peptide protegrin-1 (PG-1) is studied by molecular dynamics simulation in all-atom sodium dodecylsulfate and dodecylphosphocholine micelles. These simulations provide a high-resolution picture of the interactions between the peptide...

  7. Ionic quenching of naphthalene fluorescence in sodium dodecyl sulfate micelles.

    Science.gov (United States)

    Silva, Alessandra F; Fiedler, Haidi D; Nome, Faruk

    2011-03-31

    Micellar effects on luminescense of organic compounds or probes are well established, and here we show that quenching is highly favored in aqueous sodium dodecyl sulfate (SDS) micelles, which concentrate a naphthalene probe and cations of lanthanides, transition metals, and noble metals. Interactions have been studied by steady state and time-resolved fluorescence in examining the fluorescence suppression of naphthalene by metal ions in anionic SDS micelles. The quenching is collisional and correlated with the unit charge and the reduction potential of the metal ion. The rate constants, calculated in terms of local metal ion concentrations, are close to the diffusion control limit in the interior of SDS micelles, where the microscopic viscosity decreases the transfer rate, following the Stokes-Einstein relation.

  8. Estimation of interfacial acidity of sodium dodecyl sulfate micelles

    Indian Academy of Sciences (India)

    Arghya Dey; G Naresh Patwari

    2011-11-01

    An enhancement in the excited state proton transfer (ESPT) processes of coumarin-102 (C-102) dye was observed upon addition of salicylic acid and hydrochloric acid in sodium dodecyl sulfate (SDS) micellar solution. The phenomenon was observed only in the micellar medium of anionic surfactant SDS and not in case of cationic (CTAB) or neutral (Trition X -100) surfactants. ESPT of C-102 was also observed in aqueous solutions but on addition of very high concentrations of hydrochloric acid. However, on comparing the ratio of the protonated species from the emission spectra in the presence and absence of SDS micelle, a conclusive estimation of the local proton concentration at the Stern layer of SDS micelles could be evaluated.

  9. 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)

  10. Thermodynamics of micelle formation in a water-alcohol solution of sodium tetradecyl sulfate

    Science.gov (United States)

    Shilova, S. V.; Tret'yakova, A. Ya.; Barabanov, V. P.

    2016-01-01

    The effects of addition of ethanol and propan-1-ol on sodium tetradecyl sulfate micelle formation in an aqueous solution are studied via microprobe fluorescence microscopy and conductometry. The critical micelle concentration, quantitative characteristics of micelles, and thermodynamic parameters of micelle formation are determined. Addition of 5-15 vol % of ethanol or 5-10 vol % of propan-1-ol is shown to result in a lower critical micelle concentration than in the aqueous solution, and in the formation of mixed spherical micelles whose sizes and aggregation numbers are less than those for the systems without alcohol. The contribution from the enthalpy factor to the free energy of sodium tetradecyl sulfate micelle formation is found to dominate in mixed solvents, in contrast to aqueous solutions.

  11. Small angle neutron scattering studies of mixed micelles of sodium cumene sulphonate with cetyl trimethylammonium bromide and sodium dodecyl sulphate

    Indian Academy of Sciences (India)

    K V Padalkar; V G Gaikar; V K Aswal

    2008-11-01

    The aqueous solutions of sodium cumene sulphonate (NaCS) and its mixtures with each of cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) are characterized by small angle neutron scattering (SANS). NaCS when added to CTAB solution leads to the formation of long rod-shaped micelles with a dramatic increase in the CTAB aggregation number. Its addition to SDS on the other hand results in the formation of smaller mixed micelles where part of SDS molecules in the micelle is replaced by NaCS molecules.

  12. Atomistic Simulation of Solubilization of Polycyclic Aromatic Hydrocarbons in a Sodium Dodecyl Sulfate Micelle.

    Science.gov (United States)

    Liang, Xujun; Marchi, Massimo; Guo, Chuling; Dang, Zhi; Abel, Stéphane

    2016-04-19

    Solubilization of two polycyclic aromatic hydrocarbons (PAHs), naphthalene (NAP, 2-benzene-ring PAH) and pyrene (PYR, 4-benzene-ring PAH), into a sodium dodecyl sulfate (SDS) micelle was studied through all-atom molecular dynamics (MD) simulations. We find that NAP as well as PYR could move between the micelle shell and core regions, contributing to their distribution in both regions of the micelle at any PAH concentration. Moreover, both NAP and PYR prefer to stay in the micelle shell region, which may arise from the greater volume of the micelle shell, the formation of hydrogen bonds between NAP and water, and the larger molecular volume of PYR. The PAHs are able to form occasional clusters (from dimer to octamer) inside the micelle during the simulation time depending on the PAH concentration in the solubilization systems. Furthermore, the micelle properties (i.e., size, shape, micelle internal structure, alkyl chain conformation and orientation, and micelle internal dynamics) are found to be nearly unaffected by the solubilized PAHs, which is irrespective of the properties and concentrations of PAHs.

  13. Thermo-sensitive complex micelles from sodium alginate-graft-poly(N-isopropylacrylamide) for drug release.

    Science.gov (United States)

    Yu, Nana; Li, Guiying; Gao, Yurong; Jiang, Hua; Tao, Qian

    2016-05-01

    Polymer micelles with environmentally sensitive properties have potential applications in biomedicine. In this paper, thermo-sensitive complex micelles assembled from biocompatible graft copolymers sodium alginate-graft-poly(N-isopropylacrylamide) (SA-g-PNIPAM) and divalent metal ions were prepared for controlled drug release. The polymer micelles had core-corona structure, which was constituted by metal ions (Ba(2+), Zn(2+), Co(2+)) cross-linked sodium alginate as the core and thermo-sensitive PNIPAM chains as the corona. Formation of polymer micelles was determined by Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The polymer micelles were observed as regular spheres with good polydispersity and excellent performance on drug encapsulation and release ability. The cumulative release of 5-fluorouracil (5-FU) from micelles was controlled by pH, ionic strength or temperature of surroundings. The superior properties of sensitive polymer micelles induced by metal ions are expected to be utilized in controlled drug delivery systems.

  14. Study of sodium dodecyl sulfate-poly(propylene oxide) methacrylate mixed micelles.

    Science.gov (United States)

    Bastiat, Guillaume; Grassl, Bruno; Khoukh, Abdel; François, Jeanne

    2004-07-01

    Sodium dodecyl sulfate (SDS)-poly(propylene oxide) methacrylate (PPOMA) (of molecular weight M(w) = 434 g x mol(-1)) mixtures have been studied using conductimetry, static light scattering, fluorescence spectroscopy, and 1H NMR. It has been shown that SDS and PPOMA form mixed micelles, and SDS and PPOMA aggregation numbers, N(ag SDS) and N(ag PPOMA), have been determined. Total aggregation numbers of the micelles (N(ag SDS) + N(ag PPOMA)) and those of SDS decrease upon increasing the weight ratio R = PPOMA/SDS. Localization of PPOMA inside the mixed micelles is considered (i) using 1H NMR to localize the methacrylate function at the hydrophobic core-water interface and (ii) by studying the SDS-PPO micellar system (whose M(w) = 400 g x mol(-1)). Both methods have indicated that the PPO chain of the macromonomer is localized at the SDS micelle surface. Models based on the theorical prediction of the critical micellar concentration of mixed micelles and structural model of swollen micelles are used to confirm the particular structure proposed for the SDS-PPOMA system, i.e., the micelle hydrophobic core is primarily composed of the C12 chains of the sodium dodecyl sulfate, the hydrophobic core-water interface is made up of the SDS polar heads as well as methacrylate functions of the PPOMA, the PPO chains of the macromonomer are adsorbed preferentially on the surface, i.e., on the polar heads of the SDS.

  15. Rheological properties of wormlike micelles formed in the sodium oleate/trisodium phosphate aqueous solution

    Institute of Scientific and Technical Information of China (English)

    Yong Qiang Ji; Wei Shan Wang; Gan Zuo Li; Li Qiang Zheng

    2008-01-01

    Aqueous solution of anionic surfactant,sodium oleate (NaOA),was studied by means of steady-state shear rheology and dynamic oscillatory technique.The system of NaOA/Na3PO4 showed high viscosity,strong viscoelasticity and good ability of countering Ca2+,Mg2+.The Maxwell model and Cole-Cole plot were applied to study the dynamic viscoelasticity of wormlike micelles.The microstructures of the wormlike micelles were characterized by FF-TEM.

  16. Small-angle neutron scattering study of sodium cholate and sodium deoxycholate interacting micelles in aqueous medium

    Indian Academy of Sciences (India)

    J Santhanalakshmi; G Shantha Lakshmi; V K Aswal; P S Goyal

    2001-02-01

    Small angle neutron scattering (SANS) measurements of D2O solutions (0 1 M) of sodium cholate (NaC) and sodium deoxycholate (NaDC) were carried out at = 298 K. Under compositions very much above the critical micelle concentration (CMC), the bile salt micelle size growths were monitored by adopting Hayter-Penfold type analysis of the scattering data. NaC and NaDC solutions show presence of correlation peaks at = 0 12 and 0 1 Å-1 respectively. Monodisperse ellipsoids of the micelles produce best fits. For NaC and NaDC systems, aggregation number (9 0, 16 0), fraction of the free counterions per micelle (0 79, 0 62), semi-minor (8 0 Å) and semi-major axes (18 4, 31 7 Å) values for the micelles were deduced. Extent of micellar growth was studied using ESR correlation time measurements on a suitable probe incorporating NaC and NaDC micelles. The growth parameter (axial ratio) values were found to be 2 3 and 4 0 for NaC and NaDC systems respectively. The values agree with those of SANS.

  17. Time-resolved fluorescence quenching studies of sodium lauryl ether sulfate micelles

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Leidi C.; Silva, Volnir O.; Quina, Frank H., E-mail: quina@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Quimica; Moreira Junior, Paulo F. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Escola Politecnica. Departamento de Engenharia Quimica; Tcacenco, Celize M. [Fundacao Instituto de Ensino para Osasco (FIEO/UNIFIEO), SP (Brazil). Centro Universitario FIEO. Centro de Estudos Quimicos

    2013-02-15

    Aggregation numbers (N{sub Ag}) of micelles of the commercial anionic detergent sodium lauryl ether sulfate (SLES), with an average of two ethylene oxide subunits, were determined at 30 and 40 deg C by the time-resolved fluorescence quenching method with pyrene as the fluorescent probe and the N-hexadecylpyridinium ion as the quencher. The added-salt dependent growth of SLES micelles ({gamma} = 0.11-0.15, where {gamma} is the slope of a plot of log aggregation number vs. log [Y{sub aq}] and [Y{sub aq}] is the sodium counterion concentration free in the intermicellar aqueous phase) is found to be significantly lower than that of sodium alkyl sulfate micelles ({gamma} ca. 0.25), a difference attributed to the larger headgroup size of SLES. The I{sub 1}/I{sub 3} vibronic intensity ratio and the rate constant for intramicellar quenching of pyrene show that the pyrene solubilization microenvironment and the intramicellar microviscosity are insensitive to micelle size or the presence of added salt. (author)

  18. Time-resolved fluorescence quenching studies of sodium lauryl ether sulfate micelles

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Leidi C.; Silva, Volnir O.; Quina, Frank H., E-mail: quina@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Quimica; Moreira Junior, Paulo F. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Escola Politecnica. Departamento de Engenharia Quimica; Tcacenco, Celize M. [Fundacao Instituto de Ensino para Osasco (FIEO/UNIFIEO), SP (Brazil). Centro Universitario FIEO. Centro de Estudos Quimicos

    2013-02-15

    Aggregation numbers (N{sub Ag}) of micelles of the commercial anionic detergent sodium lauryl ether sulfate (SLES), with an average of two ethylene oxide subunits, were determined at 30 and 40 deg C by the time-resolved fluorescence quenching method with pyrene as the fluorescent probe and the N-hexadecylpyridinium ion as the quencher. The added-salt dependent growth of SLES micelles ({gamma} = 0.11-0.15, where {gamma} is the slope of a plot of log aggregation number vs. log [Y{sub aq}] and [Y{sub aq}] is the sodium counterion concentration free in the intermicellar aqueous phase) is found to be significantly lower than that of sodium alkyl sulfate micelles ({gamma} ca. 0.25), a difference attributed to the larger headgroup size of SLES. The I{sub 1}/I{sub 3} vibronic intensity ratio and the rate constant for intramicellar quenching of pyrene show that the pyrene solubilization microenvironment and the intramicellar microviscosity are insensitive to micelle size or the presence of added salt. (author)

  19. Solubilization of benzene and cyclohexane by sodium deoxycholate micelles

    Energy Technology Data Exchange (ETDEWEB)

    Christian, S.D.; Smith, L.S.; Bushong, D.S.; Tucker, E.E.

    1982-10-01

    Vapor pressure-solubility data were obtained for the aqueous systems benzene-sodium deoxycholate and cyclohexane- sodium deoxycholate at 25/sup 0/C. The results are consistent with a mass action model similar to the BET equation. Equilibrium constants are inferred to characterize interactions of hydrocarbons with solubilization sites assumed to consist of units of four deoxycholate anions. Although addition of sodium chloride increases the middle aggregation number, solubilization results are affected very little by variation in salt concentration. When pure liquid hydrocarbon standard states are employed, solubilization results for benzene and cyclohexane (at varying salt concentrations) are quite similar. 26 references.

  20. Effect of A Long Chain Carboxylate Acid on Sodium Dodecyl Sulfate Micelle Structure: A SANS Study

    Science.gov (United States)

    Patriati, Arum; Giri Rachman Putra, Edy; Seok Seong, Baek

    2010-01-01

    The effect of a different hydrocarbon chain length of carboxylate acid, i.e. dodecanoic acid, CH3(CH)10COOH or lauric acid and hexadecanoic acid, CH3(CH2)14COOH or palmitic acid as a co-surfactant in the 0.3 M sodium dedecyl sulfate, SDS micellar solution has been studied using small angle neutron scattering (SANS). The present of lauric acid has induced the SDS structural micelles. The ellipsoid micelles structures changed significantly in length (major axis) from 22.6 Å to 37.1 Å at a fixed minor axis of 16.7 Å in the present of 0.005 M to 0.1 M lauric acid. Nevertheless, this effect did not occur in the present of palmitic acid with the same concentration range. The present of palmitic acid molecules performed insignificant effect on the SDS micelles growth where the major axis of the micelle was elongated from 22.9 Å to 25.3 Å only. It showed that the appropriate hydrocarbon chain length between surfactant and co-surfactant molecules emerged as one of the determining factors in forming a mixed micelles structure.

  1. Free Energy of Scission for Sodium Laureth-1-Sulfate Wormlike Micelles.

    Science.gov (United States)

    Vogtt, Karsten; Jiang, Hanqiu; Beaucage, Gregory; Weaver, Michael

    2017-02-28

    Wormlike micelles (WLMs) are nanoscale, self-assembled components of many products from shampoos to fracking fluids due to their viscoelasticity. Their rheological behavior is largely governed by the contour length of the micelles and the concomitant propensity of the micelles to overlap and entangle. The large contour lengths, on the order of micrometers, is the result of a delicate balance between the scission enthalpy of the wormlike micelles on the one hand and entropic factors such as the mixing entropy of dispersion, the ordering of water molecules and counterions, and the mobility of branch points on the other hand. The structure and contour length of wormlike micelles assembled from sodium laureth-1-sulfate was determined at various temperatures using small-angle neutron scattering. The results allow the calculation of the enthalpy and entropy as well as the free energy of scission and are employed to critically evaluate the common methods to determine micellar scission energy from mean-field theory. Interesting behavior is observed when comparing branched and unbranched WLMs that may reflect on mechanistic differences in chain scission.

  2. Combined Quenching Mechanism of Anthracene Fluorescence by Cetylpyridinium Chloride in Sodium Dodecyl Sulfate Micelles.

    Science.gov (United States)

    Soemo, Angela R; Pemberton, Jeanne E

    2014-03-01

    The Stern-Volmer quenching constant (KSV) for quenching of anthracene fluorescence in sodium dodecyl sulfate (SDS) micelles by pyridinium chloride has been reported previously to be 520 M(-1) based on steady state fluorescence measurements. However, such measurements cannot distinguish static versus dynamic contributions to the overall quenching. In the work reported here, the quenching dynamics of anthracene in SDS micelles by cetylpyridinium chloride (CPC), an analogue of pyridinium chloride, were investigated using both steady state and time resolved fluorescence quenching. Concurrent measurement of the decrease in fluorescence intensity and lifetime of anthracene provide a quantitative evaluation of collision induced (i.e. dynamic) versus complex formation (i.e. static) quenching of the anthracene fluorophore. The results reveal that a combined quenching mechanism is operative with approximately equal constants of 249 ± 6 M(-1) and 225 ± 12 M(-1) for dynamic and static quenching, respectively.

  3. Thermodynamic analysis of unimer-micelle and sphere-to-rod micellar transitions of aqueous solutions of sodium dodecylbenzenesulfonate

    OpenAIRE

    2014-01-01

    Temperature dependence of specific conductivity of sodium dodecylbenzenesulfonate (NaDBS) aqueous solutions was analyzed. Two breaks on the plot appeared for all temperature, which suggest two micellar transitions. This has been corroborated by surface tension measurements. The first transition concentration occurs at the critical micelle concentration (CMC), whilst the second critical concentration (so-called transition micellar concentration, TMC) is due to a sphere-to-rod micelles transiti...

  4. A small-angle neutron scattering study of sodium dodecyl sulfate-poly(propylene oxide) methacrylate mixed micelles.

    Science.gov (United States)

    Bastiat, Guillaume; Grassl, Bruno; Borisov, Oleg; Lapp, Alain; François, Jeanne

    2006-03-15

    Mixed micelle of protonated or deuterated sodium dodecyl sulfate (SDS and SDSd25, respectively) and poly(propylene oxide) methacrylate (PPOMA) are studied by small-angle neutron scattering (SANS). In all the cases the scattering curves exhibit a peak whose position changes with the composition of the system. The main parameters which characterize mixed micelles, i.e., aggregation numbers of SDS and PPOMA, geometrical dimensions of the micelles and degree of ionisation are evaluated from the analysis of the SANS curves. The position q(max) of the correlation peak can be related to the average aggregation numbers of SDS-PPOMA and SDSd25-PPOMA mixed micelles. It is found that the aggregation number of SDS decreases upon increasing the weight ratio PPOMA/SDS (or SDSd25). The isotopic combination, which uses the "contrast effect" between the two micellar systems, has allowed us to determine the mixed micelle composition. Finally, the SANS curves were adjusted using the RMSA for the structure factor S(q) of charged spherical particles and the form factor P(q) of spherical core-shell particle. This analysis confirms the particular core-shell structure of the SDS-PPOMA mixed micelle, i.e., a SDS "core" micelle surrounded by the shell formed by PPOMA macromonomers. The structural parameters of mixed micelles obtained from the analysis of the SANS data are in good agreement with those determined previously by conductimetry and fluorescence studies.

  5. Correlation of Critical Micelle Concentration of Sodium Alkyl Benzenesulfonates with Molecular Descriptors

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The hydrophobic-hydrophilic segment geometries of 36 sodium alkyl benzenesulfonates were fully optimized and calculated by abini-tio RHF/6-31G(d), quantum chemical data such as the charge density, the energy of molecular orbital and the dipole moment were obtained. Based on two topological descriptors and one quantum chemical descriptor, a significant quantitative structure-property relationship (QSPR) model for the critical micelle concentration (cmc) of sodium alkyl benzenesulfonate surfactants was obtained by using the multiple linear regression technique. The good correlation coefficient of R2 (0.980) and cross-validation correlation coefficient R2cv (0.974) indicate the excellent capability and stability of the regression equation developed. In addition, linear relationships between logarithm of cmc and the dipole moment of surfactant hydrophobic hydrophilic segments for each homologous series have also been established with high correlation coefficient.

  6. Structure and dynamics of cholic acid and dodecylphosphocholine-cholic acid aggregates.

    Science.gov (United States)

    Sayyed-Ahmad, Abdallah; Lichtenberger, Lenard M; Gorfe, Alemayehu A

    2010-08-17

    Bile acids are powerful detergents that emulsify and solubilize lipids, vitamins, cholesterol and other molecules in the biliary tract and intestines. It has long been known that bile acids form soluble mixed micelles with lipids. However, the detailed thermodynamic and structural properties of these micelles are not fully understood. This study sheds light on this issue based on results from multiple molecular dynamics simulations of cholic acid (CA) and dodecylphosphocholine (DPC) mixed micelles. We found that CA molecules form aggregates of up to 12 monomers with a mean size of 5-6. In agreement with several previous simulations and earlier predictions, the overall shape of these CA clusters is oblate disk-like such that the methyl groups point toward the core of the aggregate and the hydroxyl groups point away from it. The self-aggregation behavior of the CA clusters in the DPC-CA mixture is similar to the pure CA. Furthermore, the sizes and aggregation numbers of the DPC-CA mixed micelles are linearly dependent on CA molarity. In agreement with the radial shell model of Nichols and Ozarowski [Nichols, J. W.; Ozarowski, J. Biochemistry 1990, 29, 4600], our results demonstrate that CA molecules form a wedge between the DPC molecules with their hydroxyl and carboxyl groups facing the aqueous phase while their methyl groups are buried in and face the hydrocarbon core of the DPC micelle. The DPC-CA micelles simulated here tend to be spherical to prolate in shape, with the deviation from spherical geometry significantly increasing with increasing CA:DPC ratio.

  7. 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.

  8. Stopped-flow kinetic studies of sphere-to-rod transitions of sodium alkyl sulfate micelles induced by hydrotropic salt.

    Science.gov (United States)

    Zhang, Jingyan; Ge, Zhishen; Jiang, Xiaoze; Hassan, P A; Liu, Shiyong

    2007-12-15

    The kinetics and mechanism of sphere-to-rod transitions of sodium alkyl sulfate micelles induced by hydrotropic salt, p-toluidine hydrochloride (PTHC), were investigated by stopped-flow with light scattering detection. Spherical sodium dodecyl sulfate (SDS) micelles transform into short ellipsoidal shapes at low salt concentrations ([PTHC]/[SDS], chi(PTHC)=0.3 and 0.4). Upon stopped-flow mixing aqueous solutions of spherical SDS micelles with PTHC, the scattered light intensity gradually increases with time. Single exponential fitting of the dynamic traces leads to characteristic relaxation time, tau(g), for the growth process from spherical to ellipsoidal micelles, and it increases with increasing SDS concentrations. This suggests that ellipsoidal micelles might be produced by successive insertion of unimers into spherical micelles, similar to the case of formation of spherical micelles as suggested by Aniansson-Wall (A-W) theory. At chi(PTHC) > or = 0.5, rod-like micelles with much higher axial ratio form. The scattered light intensity exhibits an initially abrupt increase and then levels off. The dynamic curves can be well fitted with single exponential functions, and the obtained tau(g) decreases with increasing SDS concentration. Thus, the growth from spherical to rod-like micelles might proceed via fusion of spherical micelles, in agreement with mechanism proposed by Ikeda et al. At chi(PTHC)=0.3 and 0.6, the apparent activation energies obtained from temperature dependent kinetic studies for the micellar growth are 40.4 and 3.6 kJ/mol, respectively. The large differences between activation energies for the growth from spherical to ellipsoidal micelles at low chi(PTHC) and the sphere-to-rod transition at high chi(PTHC) further indicate that they should follow different mechanisms. Moreover, the sphere-to-rod transition kinetics of sodium alkyl sulfate with varying hydrophobic chain lengths (n=10, 12, 14, and 16) are also studied. The longer the carbon chain

  9. Micelles in mixtures of sodium dodecyl sulfate and a bolaform surfactant.

    Science.gov (United States)

    Muzzalupo, Rita; Gente, Giacomo; La Mesa, Camillo; Caponetti, Eugenio; Chillura-Martino, Delia; Pedone, Lucia; Saladino, Maria Luisa

    2006-07-04

    Mixtures composed of water, sodium dodecyl sulfate (SDS), and a bolaform surfactant with two aza-crown ethers as polar headgroups (termed Bola C-16) were investigated by modulating the mole ratios between the components. The two surfactants have ionic and nonionic, but ionizable, headgroups, respectively. The ionization is due to the complexation of alkali ions by the aza-crown ether unit(s). Structural, thermodynamic, and transport properties of the above mixtures were investigated. Results from surface tension, translational self-diffusion, and small angle neutron scattering (SANS) are reported and discussed. Interactions between the two surfactants to form mixed micelles result in a combination of electrostatic and hydrophobic contributions. These effects are reflected in the size and shape of the aggregates as well as in transport properties. The translational diffusion of the components in mixed micelles, in particular, depends on the Bola C-16/SDS mole ratio. Nonideality of mixing of the two components was inferred from the dependence of the critical micelle concentration, cmc, on the mole fraction of Bola C-16. This behavior is also reflected in surface adsorption and in the area per polar headgroup at the air-water interface. SANS data analysis for the pure components gives results in good agreement with previous findings. An analysis of data relative to mixed systems allows us to compute some structural parameters of the mixed aggregates. The dependence of aggregation numbers, nu(T), on the Bola C-16/SDS mole ratio displays a maximum that depends on the overall surfactant content and is rationalized in terms of the nonideality of mixing. Aggregates grow perpendicularly to the major rotation axis, as formerly observed in the Bola C-16 system, and become progressively ellipsoidal in shape.

  10. Phospholipid containing mixed micelles. Characterization of diheptanoyl phosphatidylcholine (DHPC) and sodium dodecyl sulfate and DHPC and dodecyl trimethylammonium bromide.

    Science.gov (United States)

    Ranganathan, Radha; Vautier-Giongo, Carolina; Bakshi, Mandeep Singh; Bales, Barney L; Hajdu, Joseph

    2005-05-01

    Mixed micelles of l,2-diheptanoyl-sn-grycero-3-phosphocholine (DHPC) with ionic detergents were prepared to develop well characterized substrates for the study of lipolytic enzymes. The aggregates that formed on mixing DHPC with the anionic surfactant sodium dodecyl sulfate (SDS) and with the positively charged dodecyl trimethylammonium bromide (DTAB) were investigated using time-resolved fluorescence quenching (TRFQ) to determine the aggregation numbers and bimolecular collision rates, and electron spin resonance (ESR) to measure the hydration index and microviscosity of the micelles at the micelle-water interface. Mixed micelles between the phospholipid and each of the detergents formed in all compositions, yielding interfaces with varying charge, hydration, and microviscosity. Both series of micelles were found to be globular up to 0.7 mole fraction of DHPC, while the aggregation numbers varied within the same concentration range of the components less than 15%. Addition of the zwitterionic phospholipid component increased the degree of counterion dissociation as measured by the quenching of the fluorescence of pyrene by the bromide ions bound to DHPC/DTAB micelles, showing that at 0.6 mole fraction of DHPC 80% of the bromide ions are dissociated from the micelles. The interface water concentration decreased significantly on addition of DHPC to each detergent. For combined phospholipid and detergent concentration of 50 mM the interface water concentration decreased, as measured by ESR of the spin-probes, from 38.5 M/L of interface volume in SDS alone to 9 M/L when the phospholipid was present at 0.7 mole fraction. Similar addition of DHPC to DTAB decreased the interfacial water concentration from 27 M/L to 11 M/L. Determination of the physicochemical parameters of the phospholipid containing mixed micelles here presented are likely to provide important insight into the design of assay systems for kinetic studies of phospholipid metabolizing enzymes.

  11. Fabrication and study of properties of magnetite nanoparticles in hybrid micelles of polystyrene-block-polyethylene oxide and sodium dodecyl sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Loginova, T. P., E-mail: tlg@ineos.ac.ru; Timofeeva, G. I.; Lependina, O. L.; Shandintsev, V. A. [Russian Academy of Sciences, Nesmeyanov Institute of Organoelement Compounds (Russian Federation); Matyushin, A. A. [Ministry of Public Health of the Russian Federation, First Moscow State Medical University (Russian Federation); Khotina, I. A. [Russian Academy of Sciences, Nesmeyanov Institute of Organoelement Compounds (Russian Federation); Shtykova, E. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2016-01-15

    Magnetite nanoparticles have been formed for the first time in hybrid micelles of polystyrene-block-polyethylene oxide and sodium dodecyl sulfate in water by ultrasonic treatment at room temperature. An analysis by small-angle X-ray scattering and transmission electron microscopy (TEM) showed that magnetite nanoparticles in hybrid micelles of block copolymer and sodium dodecyl sulfate are polydesperse (have sizes from 0.5 to 20 nm). The specific magnetization of solid samples has been measured.

  12. Aggregation number-based degrees of counterion dissociation in sodium n-alkyl sulfate micelles.

    Science.gov (United States)

    Lebedeva, Nataly V; Shahine, Antoine; Bales, Barney L

    2005-10-27

    Values of the degree of counterion dissociation, alpha, for sodium n-alkyl sulfate micelles, denoted by SN(c)S, where N(c) is the number of carbon atoms in the alkyl chain, are defined by asserting that the aggregation number, N, is dependent only on the concentration, C(aq), of counterions in the aqueous pseudophase. By using different combinations of surfactant and added salt concentrations to yield the same value of N, alpha can be determined, independent of the experimental method. Electron paramagnetic resonance measurements of the hyperfine spacings of two nitroxide spin probes, 16- and 5-doxylstearic acid methyl ester (16DSE and 5DSE, respectively), are employed to determine whether micelles from two samples have the same value of N to high precision. The EPR spectra are different for the two spin probes, but the values of alpha are the same, within experimental error, as they must be. In agreement with recent work on S12S and with prevailing thought in the literature, values of alpha are constant as a function of N. This implies that the value of alpha is constant whether the surfactant or added electrolyte concentrations are varied. Interestingly, alpha varies with chain length as follows: N(c) = 8, alpha = 0.42 +/- 0.03; N(c) = 9, alpha = 0.41 +/- 0.03; N(c) = 10, alpha = 0.35 +/- 0.02; N(c) = 11, alpha = 0.30 +/- 0.02 at 25 degrees C and N(c) = 13, alpha = 0.22 +/- 0.02; and N(c) = 14, alpha = 0.19 +/- 0.01 at 40 degrees C. A simple electrostatic theoretical description, based on the nonlinear Poisson-Boltzmann equation for the ion distribution around a charged sphere, was compared with the experimental results. The theory predicts values of alpha that are in reasonable agreement with experiment, nicely predicting the decrease of alpha as N(c) increases. However, the theory also predicts that, for a given value of N(c), alpha decreases as N increases. Moreover, this decrease is predicted to be different if N is increased by adding salt or by increasing

  13. Temperature and Concentration Effects of Aqueous Solution of Sodium Octanoate on Micelle Formation Measured by Small angle X-ray Scattering

    Directory of Open Access Journals (Sweden)

    A.P. Kuzmenko

    2014-07-01

    Full Text Available Characteristic sizes of sodium octanoate micelles have been determined (by nucleus radius with the use of small angle X-ray scattering technique at various molar concentrations, which are for a spherical shape 1 and nonspherical 1.2 nm, respectively. The value of the critical concentration for micelle formation (CMC2 has been also found equal to 0.7 M.

  14. 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

    OpenAIRE

    Ćirin Dejan M; Poša Mihalj M.; Krstonošić Veljko S.; Milanović Maja Lj.

    2012-01-01

    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 s...

  15. Integral physicochemical properties of reverse micelles of sodium bis(2-ethylhexyl) sulfosuccinate (AOT)

    Science.gov (United States)

    Fedyaeva, O. A.; Shubenkova, E. G.; Poshelyuzhnaya, E. G.; Lutaeva, I. A.

    2016-08-01

    The effect the degree of hydration has on optical and electrophysical properties of water/AOT/ n-hexane system is studied. It is found that AOT reverse micelles form aggregates whose dimensions grow along with the degree of hydration and temperature. Aggregation enhances their electrical conductivity and shifts the UV spectrum of AOT reverse emulsions to the red region. Four states of water are found in the structure of AOT reverse micelles.

  16. Effect of 1-Butyl-3-methylimidazolium Halide on the Relative Stability between Sodium Dodecyl Sulfate Micelles and Sodium Dodecyl Sulfate-Poly(ethylene oxide) Nanoaggregates.

    Science.gov (United States)

    Ferreira, Gabriel M Dias; Ferreira, Guilherme M Dias; Agudelo, Álvaro J Patiño; Hespanhol da Silva, Maria C; Rezende, Jaqueline de Paula; Pires, Ana Clarissa Dos Santos; da Silva, Luis Henrique Mendes

    2015-12-24

    It is well-known that ionic liquids (ILs) alter the properties of aqueous systems containing only surfactants. However, the effect of ILs on polymer-surfactant systems is still unknown. Here, the effect of 1-butyl-3-methylimidazolium bromide (bmimBr) and chloride (bmimCl) on the micellization of sodium dodecyl sulfate (SDS) and its interaction with poly(ethylene oxide) (PEO) was evaluated using conductimetry, fluorimetry, and isothermal titration calorimetry. The ILs decreased the critical micellar concentration (cmc) of the surfactant, stabilizing the SDS micelles. A second critical concentration (c2thc) was verified at high SDS concentrations, due to the micelle size decrease. The stability of PEO/SDS aggregates was also affected by ILs, and the critical aggregation concentration (cac) of SDS increased. Integral aggregation enthalpy changed from -0.72 in water to 2.16 kJ mol(-1) in 4.00 mM bmimBr. IL anions did not affect the SDS micellization or the beginning of PEO/SDS aggregation. Nevertheless, when chloride was replaced with bromide, the amount of SDS bound to the polymer increased. At 100.0 mM IL, the PEO-SDS interaction vanished. We suggest that the effect of ILs comes from participating in the structure of the formed aggregates, interacting with the SDS monomers at the core/interface of the micelles, and promoting preferential solvation of the polymer.

  17. Effect of Vesicle-to-Micelle Transition on the Interactions of Phospholipid/Sodium Cholate Mixed Systems with Curcumin in Aqueous Solution.

    Science.gov (United States)

    Zhang, Sha; Wang, Xiaoyong

    2016-08-01

    The role of vesicle-to-micelle transition has been investigated in the interactions of phospholipid vesicles, phospholipid/sodium cholate (NaC) mixed vesicles, and phospholipid/NaC mixed micelles with curcumin in aqueous solution. The addition of NaC causes phospholipid vesicles to transit into phospholipid/NaC mixed vesicles and phospholipid/NaC mixed micelles. Turbidity measurement reveals that the presence of curcumin increases the NaC concentration for the solubilization of phospholipid vesicles, which indicates that the bound curcumin tends to suppress the vesicle-to-micelle transition. The pyrene polarity index and curcumin fluorescence anisotropy measurements suggest that phospholipid/NaC mixed micelles have a more compact structure than that of phospholipid vesicles and phospholipid/NaC mixed vesicles. Curcumin associated with phospholipid vesicles, phospholipid/NaC mixed vesicles, and phospholipid/NaC mixed micelles often results in higher intensities of absorption and fluorescence than those of free curcumin. However, phospholipid/NaC mixed vesicles lead to the highest values of absorption and fluorescence intensities, binding constant, and radical-scavenging capacity with curcumin. The different structures in the phospholipid bilayer of phospholipid/NaC mixed vesicles and the hydrophobic part of phospholipid/NaC mixed micelles where curcumin located are discussed to explain the interaction behaviors of phospholipid/NaC mixed systems with curcumin.

  18. Micelle enhanced and native spectrofluorimetric methods for determination of sertindole using sodium dodecyl sulfate as sensitizing agent.

    Science.gov (United States)

    El-Kosasy, Amira M; Hussein, Lobna A; Sedki, Nehal G; Salama, Nahla N

    2016-01-15

    Two stability indicating spectrofluorimetric methods were developed and validated for the determination of sertindole (SER) in the presence of its acid and oxidative degradates at λ(ex) 257 nm and λ(em) 335 nm. Method A was based on measuring the native fluorescence of SER using isopropanol as solvent. Method B was based on the enhancement of native fluorescence of SER quenched in aqueous media by using micellar microenvironment created by sodium dodecyl sulfate (SDS) anionic micelles using Britton Robinson Buffer (BRB) pH3.29 as solvent. Different factors affecting fluorescence intensity; both native and enhanced, were carefully studied to reach the optimum conditions of measurements. The proposed spectrofluorimetric methods were validated in accordance with ICH guidelines and were successfully applied for the determination of SER in bulk powder and pharmaceutical preparation with high sensitivity and stability indicating power. They were also statistically compared to the manufacturer methods with no significant difference in performance.

  19. Characterizing interfacial friction in bis(2-ethylhexyl) sodium sulfosuccinate reverse micelles from photoisomerization studies of carbocyanine derivatives

    Science.gov (United States)

    Gangamallaiah, V.; Dutt, G. B.

    2011-01-01

    Photoisomerization of two carbocyanine derivatives has been examined in bis(2-ethylhexyl) sodium sulfosuccinate (AOT) reverse micelles to understand the factors that govern this process in the interfacial region of organized assemblies. To this effect, fluorescence lifetimes and quantum yields of 3,3'-diethyloxadicarbocyanine iodide and merocyanine 540 have been measured in AOT/isooctane/water and AOT/cyclohexane/water reverse micellar systems as a function of the mole ratio of water to the surfactant, W. The nonradiative rate constants, which have been identified as the rates of photoisomerization for these solutes, were obtained from the experimentally measured parameters. The steady rise and subsequent saturation observed in the nonradiative rate constants upon increasing W has been rationalized in terms of micellar packing. An inverse correlation has been obtained between the nonradiative rate constants and the critical packing parameter, indicating that the interfacial friction experienced by the solute molecule is essentially described by this parameter.

  20. Comparison of microenvironments of aqueous sodium dodecyl sulfate micelles in the presence of inorganic and organic salts: a time-resolved fluorescence anisotropy approach.

    Science.gov (United States)

    Dutt, G B

    2005-11-08

    Microenvironments of aqueous sodium dodecyl sulfate (SDS) micelles was examined in the presence of additives such as sodium chloride and p-toluidine hydrochloride (PTHC) by monitoring the fluorescence anisotropy decays of two hydrophobic probes, 2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DMDPP) and coumarin 6 (C6). It has been well-established that SDS micelles undergo a sphere-to-rod transition and that their mean hydrodynamic radius increases from 19 to 100 A upon the addition of 0.0-0.7 M NaCl at 298 K. A similar size and shape transition is induced by PTHC at concentrations that are 20 times lower compared to that of NaCl. This study was undertaken to find out how the microviscosity of the micelles is influenced under these circumstances. It was noticed that the microviscosity of the SDS/NaCl system increased by approximately 45%, whereas there was a less than 10% variation in the microviscosity of the SDS/PTHC system. The large increase in the microviscosity of the former system with salt concentration has been rationalized on the basis of the high concentration of sodium ions in the headgroup region of the micelles and their ability to strongly coordinate with the water present in this region, which decreases the mobility of the probe molecules.

  1. Micellar copolymerization of associative polymers: study of the effect of acrylamide on sodium dodecyl sulfate-poly(propylene oxide) methacrylate mixed micelles.

    Science.gov (United States)

    Bastiat, Guillaume; Grassl, Bruno; François, Jeanne

    2005-09-15

    Mixed micelles of sodium dodecyl sulfate (SDS) and poly(propylene oxide) methacrylate (PPOMA) have been studied in the presence of acrylamide using conductimetry, fluorescence spectroscopy, and small-angle neutron scattering (SANS) under the following conditions: (i) the SDS-acrylamide binary system in water; (ii) the SDS-acrylamide-PPOMA ternary system in water. The addition of acrylamide in SDS solutions perturbs the micellization of the surfactant by decreasing the aggregation number of the micelles and increasing their ionization degree. The variations of the various micellar parameters versus the weight ratio R=PPOMA/SDS are different in the presence of acrylamide or in pure water. These differences are much more pronounced for the lower than for the higher PPOMA concentrations. There is competition between acrylamide and PPOMA and at higher PPOMA concentration, acrylamide tends to be released from SDS micelles and is completely replaced by PPOMA.

  2. Micelle bound structure and DNA interaction of brevinin-2-related peptide, an antimicrobial peptide derived from frog skin.

    Science.gov (United States)

    Bandyopadhyay, Susmita; Ng, Boon Yee; Chong, Charmaine; Lim, Ming Zhen; Gill, Sonia Kiran; Lee, Ke Hui; Sivaraman, J; Chatterjee, Chiradip

    2014-10-01

    Brevinin-2-related peptide (BR-II), a novel antimicrobial peptide isolated from the skin of frog, Rana septentrionalis, shows a broad spectrum of antimicrobial activity with low haemolytic activity. It has also been shown to have antiviral activity, specifically to protect cells from infection by HIV-1. To understand the active conformation of the BR-II peptide in membranes, we have investigated the interaction of BR-II with the prokaryotic and eukaryotic membrane-mimetic micelles such as sodium dodecylsulfate (SDS) and dodecylphosphocholine (DPC), respectively. The interactions were studied using fluorescence and circular dichroism (CD) spectroscopy. Fluorescence experiments revealed that the N-terminus tryptophan residue of BR-II interacts with the hydrophobic core of the membrane mimicking micelles. The CD results suggest that interactions with membrane-mimetic micelles induce an α-helix conformation in BR-II. We have also determined the solution structures of BR-II in DPC and SDS micelles using NMR spectroscopy. The structural comparison of BR-II in the presence of SDS and DPC micelles showed significant conformational changes in the residues connecting the N-terminus and C-terminus helices. The ability of BR-II to bind DNA was elucidated by agarose gel retardation and fluorescence experiments. The structural differences of BR-II in zwitterionic versus anionic membrane mimics and the DNA binding ability of BR-II collectively contribute to the general understanding of the pharmacological specificity of this peptide towards prokaryotic and eukaryotic membranes and provide insights into its overall antimicrobial mechanism.

  3. Interaction of quinine sulfate with anionic micelles of sodium dodecylsulfate: A time-resolved fluorescence spectroscopy at different pH

    Science.gov (United States)

    Joshi, Sunita; Pant, Debi D.

    2015-09-01

    Photophysical behavior and rotational relaxation dynamics of quinine sulfate (QS) in anionic surfactant, sodium dodecylsulfate (SDS) at different pH have been studied using steady state and time resolved fluorescence spectroscopy. It has been observed that the cationic form of quinine sulfate (at pH 2) forms a fluorescent ion pair complex with the surfactant molecules at lower concentrations of surfactant. However, for higher concentrations of SDS, the probe molecules bind strongly with the micelles and reside at the water-micelle interface. At pH 7, QS is singly protonated in bulk aqueous solution. At lower concentrations of SDS aggregation between probe and surfactant molecules has been observed. However, for higher concentrations of SDS, an additional fluorescence peak corresponding to dicationic form of QS appears and this has been attributed to double protonation of the QS molecule in micellar solution. At pH 7, in the presence of SDS micelles, the photophysical properties of QS showed substantial changes compared to that in the bulk water solution. At pH 12, an increase in fluorescence intensity and lifetime has been observed and this has been attributed to the increase in radiative rate due to the incorporation of QS at the micelle-water interface. The local pH at micellar surface has been found different from the pH of bulk solution.

  4. Rheologycal properties of sodium carboxymethylcellulose in the presence of electrolyte and mixed micelle of surfactants

    Directory of Open Access Journals (Sweden)

    Sovilj Verica J.

    2003-01-01

    Full Text Available One of the most significant aspects of polymer-surfactant interaction, from the practical point of view, is that of rheology control and viscosity enhancement. In the oppositely charged polyelectrolyte-surfactant system strong ionic interaction often leads to precipitation of the formed complex yielding serious problems. In this paper the interaction between anionic polyelectrolyte - sodium carboxymethylcellulose (NaCMC and cationic surfactant - cethyltrimethylammonium bromide (CTMAB has been investigated by rheological measurements. Addition of electrolyte NaBr and nonionic surfactant - Tween 80 reduced the binding strength, prevented the precipitation of the complex and increased the viscosity of the system. It was found that rheological properties are strong influenced by NaCMC-CTMAB interaction and the system exhibits either pseudoplastic or thixotropic or rheopectic behavior according to the intensity of interaction.

  5. 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.

  6. Thermodynamics and Structural Evolution during a Reversible Vesicle-Micelle Transition of a Vitamin-Derived Bolaamphiphile Induced by Sodium Cholate.

    Science.gov (United States)

    Tian, Jun-Nan; Ge, Bing-Qiang; Shen, Yun-Feng; He, Yu-Xuan; Chen, Zhong-Xiu

    2016-03-09

    Interaction of endogenous sodium cholate (SC) with dietary amphiphiles would induce structural evolution of the self-assembled aggregates, which inevitably affects the hydrolysis of fat in the gut. Current work mainly focused on the interaction of bile salts with classical double-layered phospholipid vesicles. In this paper, the thermodynamics and structural evolution during the interaction of SC with novel unilamellar vesicles formed from vitamin-derived zwitterionic bolaamphiphile (DDO) were characterized. It was revealed that an increased temperature and the presence of NaCl resulted in narrowed micelle-vesicle coexistence and enlarged the vesicle region. The coexistence of micelles and vesicles mainly came from the interaction of monomeric SC with DDO vesicles, whereas micellar SC contributed to the total solubilization of DDO vesicles. This research may enrich the thermodynamic mechanism behind the structure transition of the microaggregates formed by amphiphiles in the gut. It will also contribute to the design of food formulation and drug delivery system.

  7. The effect of linoleic acid on pH inside sodium bis(2-ethylhexyl)sulfosuccinate reverse micelles in isooctane and on the enzymic activity of soybean lipoxygenase.

    Science.gov (United States)

    Rodakiewicz-Nowak, J; Maślakiewicz, P; Haber, J

    1996-06-01

    The effective pH of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles (pHrm), containing buffers of different pH (pHst) and various amounts of linoleic acid, was studied within the range of compositions used to study the activity of soybean lipoxygenase in reverse micelles. Significant shifts of pHrm versus pHst were observed for the solutions of relatively higher pHst, dependent on linoleic acid and buffer concentrations. The effect diminished as pHst became closer to 7. When low-ionic-strength buffers were added to AOT solutions in isooctane, a significant buffering effect of linoleic acid in reverse micelles was observed. Solubilization of > 3 mM linoleic acid in micellar solutions containing 25 mM buffers gave the observed pHrm values almost independent of pHst. This effect diminished with the ionic strength of the buffering solution, but did not vanish even at 200 mM buffer. The observed effects result from the balance between ionization of linoleic acid and its partition between the water pool and the micellar interface. The enzymic activity of soybean lipoxygenase in the AOT reverse micellar solutions of the determined pHrm values was also studied. A significant reduction of the kinetics of the enzymic activity was observed, for all studied reverse micellar solutions. Changes of pHrm, caused by the presence of acidic substrate (linoleic acid) do not explain the observed reduction of activity directly through the effect on the enzyme. Due to unfavourable partition of the substrate between the microphases present in the systems, enhanced by reduction of pH at higher total concentrations of linoleic acid, the saturation of the enzyme with the substrate was not observed in the system and is difficult to attain experimentally in reverse micelles. A shift of the lipoxygenase activity/pHrm profile but negligible shift of the activity/pHst profile, with respect to aqueous buffer solutions, were observed. This indicates that either the information given

  8. Polymerization of anionic wormlike micelles.

    Science.gov (United States)

    Zhu, Zhiyuan; González, Yamaira I; Xu, Hangxun; Kaler, Eric W; Liu, Shiyong

    2006-01-31

    Polymerizable anionic wormlike micelles are obtained upon mixing the hydrotropic salt p-toluidine hydrochloride (PTHC) with the reactive anionic surfactant sodium 4-(8-methacryloyloxyoctyl)oxybenzene sulfonate (MOBS). Polymerization captures the cross-sectional radius of the micelles (approximately 2 nm), induces micellar growth, and leads to the formation of a stable single-phase dispersion of wormlike micellar polymers. The unpolymerized and polymerized micelles were characterized using static and dynamic laser light scattering, small-angle neutron scattering, 1H NMR, and stopped-flow light scattering. Stopped-flow light scattering was also used to measure the average lifetime of the unpolymerized wormlike micelles. A comparison of the average lifetime of unpolymerized wormlike micelles with the surfactant monomer propagation rate was used to elucidate the mechanism of polymerization. There is a significant correlation between the ratio of the average lifetime to the monomer propagation rate and the average aggregation number of the polymerized wormlike micelles.

  9. Dynamic and spectroscopic studies of nano-micelles comprising dye in water/ dioctyl sodium sulfosuccinate /decane droplet microemulsion at constant water content

    Science.gov (United States)

    Rahdar, Abbas; Almasi-Kashi, Mohammad

    2017-01-01

    In the present work, the dynamic and spectroscopic properties of water-in-decane dioctyl sodium sulfosuccinate (AOT) microemulsions comprising dye, Rhodamine B (RB), were studied by varying content of decane at the constant water content (W = 20), by using dynamic light scattering (DLS), UV/visible, and fluorescence techniques. The characterization results of DLS of AOT micelles showed that by decreasing concentration of Rhodamine B in the water/AOT/decane microemulsion, the inter-droplet interactions changed from attractive to repulsive as the mass fraction of nano-droplets (MFD) increased. A deviation in the absorption spectra of Rhodamine B from the Beer's law at the high Rhodamine B concentration (0.001) was observed in the AOT reversed micelles. The Quenching in the emission intensity of AOT droplets comprising Rhodamine B and red shift in λmax of fluorescence of dye was observed as a function of concentration of RB in AOT RMs. The Stokes shift of AOT droplets containing the high concentration of RB, increased with mass fraction of nano-droplet (MFD), whereas at the low Rhodamine B concentration, its variation remained constant up to MFD = 0.07, and then increased.

  10. THE PREPARATION OF LIPOSOMES DERIVED FROM MIXED MICELLES OF LECITHIN ADDED BY SODIUM CHOLATE, FOLLOWED BY DIALYSING USING HEMOFLOW HIGH FLUX F60S

    Directory of Open Access Journals (Sweden)

    Rolf Schubert

    2004-12-01

    Full Text Available Liposomes are used for drug carriers meaning that drugs are incorporated in the membrane or the vesicle of the liposomes. In this study, liposomes were prepared from mixed micelles, consisting of phosphatidylcholine, without or with cholesterol and sodium cholate was added in several ratios namely 0.44; 0.55; 0.63; 0.70; 0.90 and 1.10. After the preparation, the sodium cholate has been removed by a dialysis membrane, using the Hemoflow High Flux, which is generally used for haemodialysis. The Hemoflow High Flux is a tool in an effort to obtain a simple, quick, effective method for removing sodium cholate in the process of preparing liposomes. The effectiveness of this tool was proved by the particle size of the liposome which was measured by the Malvern Particle Sizer. The particle size of the liposome consisting of phosphatidylcholine (PC without cholesterol and with cholesterol was 63-68 nm at all ratios and approximately 125 nm at the ratio of 0.55; 0.63; 0.70, respectively. The particle size of the liposome tended to be smaller after dialyzing, although the concentration of lipids tended to increase. However, a large amount of buffer solution has to be used with this method.

  11. Micelles Hydrodynamics

    CERN Document Server

    Svintradze, David V

    2016-01-01

    A micelle consists of monolayer of lipid molecules containing hydrophilic head and hydrophobic tail. These amphiphilic molecules in aqueous environment aggregate spontaneously into monomolecular layer held together due to hydrophobic effect by weak non-covalent forces. Micelles are flexible surfaces that show variety of shapes of different topology, but remarkably in mechanical equilibrium conditions they are spherical in shape. The shape and size of a micelle are functions of many variables such as lipid concentration, temperature, ionic strength, etc. Addressing the question, why the shape of micelles is sphere in mechanical equilibrium conditions, analytically proved to be a difficult problem. In the following paper we offer the shortest and elegant analytical proof of micelles spheroidal nature when they are thermodynamically equilibrated with solvent. The formalism presented in this paper can be readily extended to any homogenous surfaces, such are vesicles and membranes.

  12. 分子动力学模拟研究盐离子对十二烷基硫酸钠胶束溶液中亲水亲油协调机制的影响%Molecular Dynamics Simulation of Effect of Salt on the Compromise of Hydrophilic and Hydrophobic Interactions in Sodium Dodecyl Sulfate Micelle Solutions

    Institute of Scientific and Technical Information of China (English)

    高健; 任瑛; 葛蔚

    2009-01-01

    The presence of salt has a profound effect on the size, shape and structure of sodium dodecyl sulfate (SDS) micelles. There have been a great number of experiments on SDS micelles in the presence and absence of salt to study this complex problem. Unfortunately, it is not clear yet how electrolyte ions influence the structure of micelles. By describing the compromise between dominant mechanisms, a simplified atomic model of SDS in presence of salt has been developed and the molecular dynamics (MD) simulations of two series of systems with different concentrations of salt and charges of ion have been performed. Polydispersity of micelle size is founded at relatively high concentration of SDS and low charge of cation. Although the counter-ion pairs with head groups are formed, the transition of micelle shape is not observed because the charge of cation is not enough to neutralize the polar of micelle surface.

  13. Temperature-dependent solvation dynamics of water in sodium bis(2-ethylhexyl)sulfosuccinate/isooctane reverse micelles.

    Science.gov (United States)

    Mitra, Rajib Kumar; Sinha, Sudarson Sekhar; Pal, Samir Kumar

    2008-01-01

    In this paper, for the first time, we report a detailed study of the temperature-dependent solvation dynamics of a probe fluorophore, coumarin-500, in AOT/isooctane reverse micelles (RMs) with varying degrees of hydration (w0) of 5, 10, and 20 at four different temperatures, 293, 313, 328, and 343 K. The average solvation time constant becomes faster with the increase in w0 values at a particular temperature. The solvation dynamics of a RM with a fixed w0 value also becomes faster with the increase in temperature. The observed temperature-induced faster solvation dynamics is associated with a transition of bound- to free-type water molecules, and the corresponding activation energy value for the w0 = 5 system has been found to be 3.4 kcal mol-1, whereas for the latter two systems, it is approximately 5 kcal mol-1. Dynamic light scattering measurements indicate an insignificant change in size with temperature for RMs with w0 = 5 and 10, whereas for a w0 = 20 system, the hydrodynamic diameter increases with temperature. Time-resolved fluorescence anisotropy studies reveal a decrease in the rotational restriction on the probe with increasing temperature for all systems. Wobbling-in-cone analysis of the anisotropy data also supports this finding.

  14. Dancing retro: solution structure and micelle interactions of the retro-SH3-domain, retro-SHH-'Bergerac'.

    Science.gov (United States)

    Kutyshenko, Victor P; Prokhorov, Dmitry A; Molochkov, Nikolaj V; Sharapov, Mars G; Kolesnikov, Igor; Uversky, Vladimir N

    2014-01-01

    A protein with the reversed direction of its polypeptide chain, retro-SHH, was analyzed by several spectroscopic techniques including circular dichroism and high-resolution NMR to understand its solution structure and structural consequences of interaction with the micelles formed by the zwitterionic detergent dodecylphosphocholine (DPC). This analysis revealed that retro-SHH does not contain rigid 3-D structure, but is characterized by the presence of residual secondary structure. Intriguingly, interaction with the DPC micelles affected the structures of SHH and retro-SHH very differently. In fact, micelles induce pronounced folding of retro-SHH, whereas micelle-bound SHH was noticeably disordered. Finally, we performed a disorder prediction with the PONDR-FIT algorithm and discovered that the reversal of the chain direction almost does not affect the propensity of a polypeptide for intrinsic disorder, since the disorder plot for retro-SHH was almost a mirror image of that for the normal SHH.

  15. New Insights into the Dynamics of Zwitterionic Micelles and Their Hydration Waters by Gigahertz-to-Terahertz Dielectric Spectroscopy

    CERN Document Server

    George, Deepu K; Hull, Olivia A; Mishra, Archana; Capelluto, Daniel G S; Mitchell-Koch, Katie R; Vinh, Nguyen Q

    2016-01-01

    Gigahertz-to-terahertz spectroscopy of macromolecules in aqueous environments provides an important approach for identifying their global and transient molecular structures, as well as directly assessing hydrogen-bonding. We report dielectric properties of zwitterionic dodecylphosphocholine (DPC) micelles in aqueous solutions over a wide frequency range, from 50 MHz to 1.12 THz. The dielectric relaxation spectra reveal different polarization mechanisms at the molecular level, reflecting the complexity of DPC micelle-water interactions. We have made a deconvolution of the spectra into different components and combined them with the effective-medium approximation to separate delicate processes of micelles in water. Our measurements demonstrate reorientational motion of the DPC surfactant head groups within the micelles, and two levels of hydration water shells, including tightly- and loosely-bound hydration water layers. From the dielectric strength of bulk water in DPC solutions, we found that the number of wa...

  16. Micelle Catalysis of an Aromatic Substitution Reaction

    Science.gov (United States)

    Corsaro, Gerald; Smith J. K.

    1976-01-01

    Describes an experiment in which the iodonation of aniline reaction is shown to undergo catalysis in solution of sodium lauryl sulfate which forms micelles with negatively charged pseudo surfaces. (MLH)

  17. Formação de micelas mistas entre o sal biliar colato de sódio e o surfactante aniônico dodecanoato de sódio Mixed micelles formation between bile salt sodium cholate and the anionic surfactant sodium dodecanoate

    Directory of Open Access Journals (Sweden)

    Renato Eising

    2008-01-01

    Full Text Available Mixed-micelle formation between sodium chlolate (NaC and the anionic surfactant sodium dodecanoate (SDoD in Tris-HCl buffer solutions, pH 9.00, varying the molar fraction of the surfactants, was investigated by means of electrical conductivity and steady-state fluorescence of pyrene. The critical micelar concentration (cmc was measured from the equivalent conductance versus the square root of the molar surfactant concentration plots and the regular solution theory (RST was used to predict the mixing behavior. The I1/I3 pyrene ratio-surfactant concentration plots were used as an additional technique to follow the behavior and the changes in the micropolarity of the mixed micelles.

  18. Solution structures of the cytoplasmic linkers between segments S4 and S5 (S4-S5) in domains III and IV of human brain sodium channels in SDS micelles.

    Science.gov (United States)

    Miyamoto, K; Nakagawa, T; Kuroda, Y

    2001-09-01

    The two cytoplasmic linkers connecting segment S4 and segment S5 (S4-S5 linker) of both domain III (III/S4-S5) and IV (IV/S4-S5) of the sodium channel alpha-subunit are considered to work as a hydrophobic receptor for the inactivation particle because of the three hydrophobic amino acids of Ile-Phe-Met (IFM motif) in the III-IV linker of the sodium channel alpha-subunit. To date, the solution structures of the peptides related to III/S4-S5 (MP-D3: A1325-M1338) and IV/S4-S5 (MP-D4: T1648-L1666) of human brain sodium channels have been investigated using CD and (1)H NMR spectroscopies. SDS micelles were employed as a solvent. The micelles mimic either biological membranes or the interior of a protein and can be a relevant environment at the inactivated state of the channels. It was found that the secondary structures of both MP-D3 and MP-D4 assume alpha-helical conformations around the N-terminal half-side of the sequences, i.e. the residues between V1326 and L1331 in MP-D3 and between L1650 and S1656 in MP-D4. Residue A1329 in MP-D3, which is considered to interact with F1489 of the IFM motif, was found to be located within the alpha-helix. Residues F1651, M1654, M1655, L1657 and A1669 in MP-D4, which also play an important role in inactivation, formed a hydrophobic cluster on one side of the helix. This cluster was concluded to interact with the hydrophobic cluster due to the III-IV linker before the inactivation gate closes.

  19. Effect of micelle interface on the binding of anticoccidial PW2 peptide

    Energy Technology Data Exchange (ETDEWEB)

    Tinoco, Luzineide W. [Universidade Federal do Rio de Janeiro, Nucleo de Pesquisas de Produtos Naturais (Brazil); Gomes-Neto, Francisco; Valente, Ana Paula; Almeida, Fabio C. L. [Universidade Federal do Rio de Janeiro, Centro Nacional de Ressonancia Magnetica Nuclear Jiri Jonas, Instituto de Bioquimica Medica, Programa de Biologia Estrutural (Brazil)], E-mail: falmeida@cnrmn.bioqmed.ufrj.br

    2007-12-15

    PW2 is an anticoccidial peptide active against Eimeria acervulina and Eimeria tenella. We determined the structure of PW2 in dodecylphosphocholine micelles. The structure showed two distinct regions: an amphipathic N-terminal 3{sub 10} helix and an aromatic region containing WWR interface-binding motif. The aromatic region acted as a scaffold of the protein in the interface and shared the same structure in both DPC and SDS micelles. N-terminal helix interacted with DPC but not with SDS interface. Chemical shift change was slow when SDS was added to PW2 in DPC and fast when DPC was added to PW2 in SDS, indicating that interaction with DPC micelles was kinetically more stable than with SDS micelles. Also, DPC interface was able to accommodate PW2, but it maintained the conformational arrangement in the aromatic region observed for SDS micelles. This behavior, which is different from that observed for other antimicrobial peptides with WWR motif, may be associated with the absence of PW2 antibacterial activity and its selectivity for Eimeria parasites.

  20. Oligomerization of protegrin-1 in the presence of DPC micelles. A proton high-resolution NMR study.

    Science.gov (United States)

    Roumestand, C; Louis, V; Aumelas, A; Grassy, G; Calas, B; Chavanieu, A

    1998-01-16

    Protegrins are members of a family of five Cys-rich naturally occurring cationic antimicrobial peptides. The NMR solution structure of protegrin-1 (PG-1) has been previously determined as a monomeric beta-hairpin both in water and in dimethylsulfoxide solution. Protegrins are bactericidal peptides but their mechanism of action is still unknown. In order to investigate the structural basis of their cytotoxicity, we studied the effect of lipid micelles on the structure of PG-1. The NMR study reported in the present work indicates that PG-1 adopts a dimeric structure when it binds to dodecylphosphocholine micelles. Moreover, the amide proton exchange study suggests the possibility of an association between several dimers.

  1. Solution structure of the transmembrane domain of the insulin receptor in detergent micelles.

    Science.gov (United States)

    Li, Qingxin; Wong, Ying Lei; Kang, CongBao

    2014-05-01

    The insulin receptor (IR) binds insulin and plays important roles in glucose homeostasis by regulating the tyrosine kinase activity at its C-terminus. Its transmembrane domain (TMD) is shown to be important for transferring conformational changes induced by insulin across the cell membrane to regulate kinase activity. In this study, a construct IR(940-988) containing the TMD was expressed and purified for structural studies. Its solution structure in dodecylphosphocholine (DPC) micelles was determined. The sequence containing residues L962 to Y976 of the TMD of the IR in micelles adopts a well-defined helical structure with a kink formed by glycine and proline residues present at its N-terminus, which might be important for its function. Paramagnetic relaxation enhancement (PRE) and relaxation experimental results suggest that residues following the TMD are flexible and expose to aqueous solution. Although purified IR(940-988) in micelles existed mainly as a monomeric form verified by gel filtration and relaxation analysis, cross-linking study suggests that it may form a dimer or oligomers under micelle conditions.

  2. 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.

  3. N-椰油酰基复合氨基酸钠的胶束化热力学特性的研究%Thermodynamic properties of micelle of N-coconut oil acyl amino acids sodium

    Institute of Scientific and Technical Information of China (English)

    程海涛

    2011-01-01

    The equilibrium and dynamic surface tensions of sodium N-coconut oil acyl amino acids,which were synthesized using waste silk as raw material,were measured by wilhelmy plate method.At the same time,both the critical micelle concentrations(cmc)and standard thermodynamical functions such asΔGθm,ΔHθmandΔSθm at temperatures of 30 ℃,35 ℃,40 ℃,45 ℃ were calculated respectively.The results showed that the process is driven byΔSθm.The equation of CMC-T was obtained.Average value of the ion binding constant between micelle and reverse ions K0 is 0.874 3.Meanwhile,the effects of temperature and concentration on diffusion constant Da and Ea were studied and adsorption process model was discussed.%用Wilhelmy法测定了实验室以废丝为原料制备的氨基酸型表面活性剂N-椰油酰基复合氨基酸钠溶液的平衡和动态表面张力,计算得出N-椰油酰基复合氨基酸钠溶液在30℃、35℃、40℃和45℃时的cmc值和其胶束形成的标准热力学函数ΔGθm、ΔHθm和ΔSθm,说明该胶束的形成是熵驱动过程。得到临界胶束浓度cmc与温度T的回归方程。胶束和反离子结合常数K0平均值为0.874 3。同时,研究了浓度及温度对扩散常数Da和Ea的影响及吸附过程模型。

  4. 光度法研究十二烷基硫酸钠的临界胶束浓度%Determination of critical micelle concentration of sodium dodecyl sulfate by using spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    王新红; 戴兢陶; 顾云兰

    2011-01-01

    Critical micelle concentrations (CMC) of sodium dodecyl sulfate (SDS) in aqueous solution of io dine and I-3 solution were determined, and two salts, sodium sulfate and potassium chloride on the impact of CMC of SDS in the aqueous solution of iodine in different concentrations of iodine were also discussed.The CMC of SDS obtained in two different systems are different by using spectrophotometry. Sodium sul fate salts on the impact of the surface activity of SDS are greater than potassium chloride in I-3 solution, and with the increasing concentration of iodine, the CMC of SDS show the trend of increasing in the aqueous so lution of iodine.%在碘的水溶液和I-3溶液2种体系中测定了十二烷基硫酸钠(SDS)的临界胶束浓度(CMC),讨论了在I-3体系中,不同硫酸钠和氯化钾对测定结果的影响,在碘的水溶液中研究了不同碘浓度对SDS的CMC的影响.采用分光光度法求得SDS在两种体系中的CMC值,硫酸钠与氯化钾对CMC的值有影响,且硫酸钠对SDS的表面活性影响大于氯化钾;在碘的水溶液中,随碘的浓度增大,CMC呈增大趋势.

  5. Regulation of sodium channel function by bilayer elasticity: the importance of hydrophobic coupling. Effects of Micelle-forming amphiphiles and cholesterol

    DEFF Research Database (Denmark)

    Lundbæk, Jens August; Birn, Pia; Hansen, Anker J

    2004-01-01

    be a general mechanism regulating membrane protein function, we examined whether voltage-dependent skeletal-muscle sodium channels, expressed in HEK293 cells, are regulated by bilayer elasticity, as monitored using gramicidin A (gA) channels. Nonphysiological amphiphiles (beta-octyl-glucoside, Genapol X-100...

  6. Study of the interaction between glucosamine hydrochloride and sodium dodecylsulphate micelles using conductometric, isothermal calorimetry, zeta-potential titrations, and NMR NOESY

    OpenAIRE

    Alves,Marcos Roberto de Abreu; VIRTUOSO, Luciano Sindra

    2014-01-01

    The aim of this work was to investigate the influence of an anti-inflammatory agent, the bulky counterion named glucosamine (Gl+), in sodium dodecylsulphate (SDS) in 2 ways: 1) by titration of SDS solutions with different concentrations of Gl+; and 2) by titration of Gl+ with SDS solution with concentration close to the critical micellar concentration (cmc) (7.7 mM). In procedure 1, micellisation study by isothermal titration calorimetry (ITC) showed that the increase in Gl+ concentrat...

  7. Kinetic analysis of hydrogen production using anaerobic bacteria in reverse micelles

    Energy Technology Data Exchange (ETDEWEB)

    Zhi, Xiaohua; Yang, Haijun; Yuan, Zhuliang; Shen, Jianquan [Beijing National Laboratory for Molecular Sciences (BNLMS), Laboratory of New Materials, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun North First Street 2, Beijing 100190 (China)

    2010-04-15

    The micellar formation and entrapment of bacteria cell in reverse micelles were investigated by ultraviolet spectrum (UV), fluorescence spectrum, and scanning electron microscope (SEM). The hydrogen production in reverse micelles was confirmed. The Gompertz equation was employed to evaluate the hydrogen-producing behavior in reverse micellar systems. Different systems including dioctyl sulfosuccinate sodium salt (AOT)-isooctane, sodium dodecyl sulfate (SDS)-benzene and SDS-carbon tetrachloride (CCl{sub 4}) reverse micelles were analysized. The results revealed that the maximum rate of hydrogen production (R{sub m}) was also suitable to formulate the relationship between hydrogen-producing rate and hydrogen productivity in reverse micelles. (author)

  8. Highly Viscoelastic Worm-Like Micelle Solution of Sodium Hexadecyl Sulfate Induced by Bolaform Counterions%Bola反离子诱导的高粘弹十六烷基硫酸钠蠕虫胶束溶液

    Institute of Scientific and Technical Information of China (English)

    赵剑曦; 杨铎平

    2012-01-01

    利用稳态和频率扫描研究了十六烷基硫酸钠(SHS)与Bola盐(N,N'-双乙基二甲基-α,ω-乙烷溴化铵(Bola2Et)或N,N'-三甲基-α,ω-丁烷溴化铵(Bola4)混合体系的流变行为.实验结果表明两个体系均在45℃时形成了长蠕虫胶束,溶液呈现出高粘弹性,尤其是SHS/Bola2Et溶液表现出很高的弹性,零剪接粘度高达2520 Pa·s,表观上呈现胶状.这些结果归因于在Bola反离子诱导下,表面活性剂SHS与Bola反离子形成了静电吸引的2:1结构复合物.由于这两个Bola反离子的联接链长度均短于季铵离子的静电平衡距离,因此形成的复合物在形状上有利于蠕虫胶束生成.作为对比,添加简单的四甲基铵反离子无法诱导SHS形成蠕虫胶束,溶液仅呈现低粘度.%The rheological behaviors of mixed aqueous solutions of sodium hexadecyl sulfate (SHS) and a bolaform salt,either N,N'-ethanediyl-α,ω-bis(ethyldimethylammonium bromide) (Bola2Et) or N,N'-propanediyl-α,ω-bis(trimethylammonium bromide) (Bola4),were investigated by steady-state and frequencysweep measurements.The results showed that long worm-like micelles were formed in both systems at 45 ℃,and the solutions exhibited high viscoelasticities,especially the SHS/Bola2Et system in which the solution had very high elasticity.The zero-shear viscosity of SHS/Bola2Et was as high as 2520 Pa· s,and the system was gel-like.These results were attributed to the formation of 2:1 complexes by electrostatic attraction.Since the spacers of both Bola counterions were shorter than the distance between quaternary ammonium ions under electrostatic equilibrium,the generated complex in shape favored formation of worm-like micelles.In comparison,it was difficult to induce SHS to form worm-like micelles by the addition of tetramethylammonium counterions,and the solution exhibited low viscosity.

  9. 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.

  10. Effect of Micelle Composition on Acidic Drugs Separation Behavior by Micellar Electrokinetic Capillary Chromatography

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Micellar electrokinetic capillary chromatography (MECC) separation of four acidic drugs similar in structure was studied. Both anionic surfactant sodium dodecyl sulfate (SDS) and nonionic surfactant Tween 20 were used to form single micelles and mixed micelles as pseudostationary phases. The effects of the composition of micellar solution on retention behaviors were studied. The results indicate that there is markedly different selectivity among SDS, Tween 20 and the mixed micelles systems.

  11. Complex coacervate core micelles.

    Science.gov (United States)

    Voets, Ilja K; de Keizer, Arie; Cohen Stuart, Martien A

    2009-01-01

    In this review we present an overview of the literature on the co-assembly of neutral-ionic block, graft, and random copolymers with oppositely charged species in aqueous solution. Oppositely charged species include synthetic (co)polymers of various architectures, biopolymers - such as proteins, enzymes and DNA - multivalent ions, metallic nanoparticles, low molecular weight surfactants, polyelectrolyte block copolymer micelles, metallo-supramolecular polymers, equilibrium polymers, etcetera. The resultant structures are termed complex coacervate core/polyion complex/block ionomer complex/interpolyelectrolyte complex micelles (or vesicles); i.e., in short C3Ms (or C3Vs) and PIC, BIC or IPEC micelles (and vesicles). Formation, structure, dynamics, properties, and function will be discussed. We focus on experimental work; theory and modelling will not be discussed. Recent developments in applications and micelles with heterogeneous coronas are emphasized.

  12. Precipitate-Coacervate Transformation in Polyelectrolyte-Mixed Micelle Systems.

    Science.gov (United States)

    Comert, Fatih; Nguyen, Duy; Rushanan, Marguerite; Milas, Peker; Xu, Amy Y; Dubin, Paul L

    2017-05-04

    The polycation/anionic-nonionic mixed micelle, poly(diallyldimethylammonium chloride)-sodium dodecyl sulfate/Triton X-100 (PDADMAC-SDS/TX100), is a model polyelectrolyte-colloid system in that the micellar mole fraction of SDS (Y) controls the micelle surface charge density, thus modulating the polyelectrolyte-colloid interaction. The exquisite temperature dependence of this system provides an important additional variable, controlling both liquid-liquid (L-L) and liquid-solid (L-S) phase separation, both of which are driven by the entropy of small ion release. In order to elucidate these transitions, we applied high-precision turbidimetry (±0.1 %), isothermal titration calorimetry, and epifluorescence microscopy which demonstrates preservation of micelle structure under all conditions. The L-S region at large Y including precipitation displays a remarkable linear, inverse Y-dependence of the L-S transition temperature Ts. In sharp contrast, the critical temperature for L-L coacervation Tφ, shows nearly symmetrical effects of positive and negative deviations in Y from the point of soluble complex neutrality, which is controlled in solution by the micelle charge and the number of micelles bound per polymer chain n (Zcomplex = Zpolymer + nZmicelle). In solid-like states, n no longer signifies the number of micelles bound per polymer chain, since the proximity of micelles inverts the host-guest relationship with each micelle binding multiple PE chains. This intimate binding goes hand-in-hand with the entropy of release of micelle-localized charge-compensating ions whose concentration depends on Y. These ions need not be released in L-L coacervation, but during L-S transition their displacement by PE accounts for the inverse dependence of Ts on micelle charge, Y.

  13. 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

  14. High-resolution NMR structure of the antimicrobial peptide protegrin-2 in the presence of DPC micelles

    Energy Technology Data Exchange (ETDEWEB)

    Usachev, K. S., E-mail: k.usachev@kpfu.ru; Efimov, S. V.; Kolosova, O. A.; Filippov, A. V.; Klochkov, V. V. [Kazan Federal University (Russian Federation)

    2015-04-15

    PG-1 adopts a dimeric structure in dodecylphosphocholine (DPC) micelles, and a channel is formed by the association of several dimers but the molecular mechanisms of the membrane damage by non-α-helical peptides are still unknown. The formation of the PG-1 dimer is important for pore formation in the lipid bilayer, since the dimer can be regarded as the primary unit for assembly into the ordered aggregates. It was supposed that only 12 residues (RGGRL-CYCRR-RFCVC-V) are needed to endow protegrin molecules with strong antibacterial activity and that at least four additional residues are needed to add potent antifungal properties. Thus, the 16-residue protegrin (PG-2) represents the minimal structure needed for broad-spectrum antimicrobial activity encompassing bacteria and fungi. As the peptide conformation and peptide-to-membrane binding properties are very sensitive to single amino acid substitutions, the solution structure of PG-2 in solution and in a membrane mimicking environment are crucial. In order to find evidence if the oligomerization state of PG-1 in a lipid environment will be the same or not for another protegrins, we investigate in the present work the PG-2 NMR solution structure in the presence of perdeuterated DPC micelles. The NMR study reported in the present work indicates that PG-2 form a well-defined structure (PDB: 2MUH) composed of a two-stranded antiparallel β-sheet when it binds to DPC micelles.

  15. On the composition fluctuations of reverse micelles.

    Science.gov (United States)

    Tovstun, Sergey A; Razumov, Vladimir F

    2010-11-15

    The polydispersity of the reverse micelles is determined mainly by the fluctuations of their composition. The composition of the reverse micelle is a two-dimensional random variable whose components are the numbers of water (i) and surfactant (j) molecules. In this study the fluctuations of the composition of the reverse micelles are considered in the Gaussian approximation. It is shown that the standard deviation of the quantity w=i/j may be calculated from the dependence of the water vapor pressure above the microemulsion on the molar ratio W=[water]/[surfactant]. The estimation based on the literature data for microemulsion system sodium bis(2-ethylhexyl)sulfosuccinate/water/isooctane at 37°C in the range W=0-18 has shown that the relative standard deviation of the quantity w is about 10%. It is shown that the value of the composition fluctuations is related to the dependence of average composition on the concentration of reverse micelles at constant parameter W.

  16. Effect of compressed CO2 on the critical micelle concentration and aggregation number of AOT reverse micelles in isooctane.

    Science.gov (United States)

    Chen, Jing; Zhang, Jianling; Han, Buxing; Feng, Xiaoying; Hou, Minqiang; Li, Wenjing; Zhang, Zhaofu

    2006-10-25

    The effect of compressed CO2 on the critical micelle concentration (cmc) and aggregation number of sodium bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles in isooctane solution was studied by UV/Vis and fluorescence spectroscopy methods in the temperature range of 303.2-318.2 K and at different pressures or mole fractions of CO2 (X(CO2)). The capacity of the reverse micelles to solubilize water was also determined by direct observation. The standard Gibbs free energy (DeltaGo(m)), standard enthalpy (DeltaHo(m)), and standard entropy (DeltaSo(m)) for the formation of the reverse micelles were calculated by using the cmc data determined. It was discovered that the cmc versus X(CO2) curve and the DeltaGo(m) versus X(CO2) curve for a fixed temperature have a minimum, and the aggregation number and water-solubilization capacity of the reverse micelles reach a maximum at the X(CO2) value corresponding to that minimum. These results indicate that CO2 at a suitable concentration favors the formation of and can stabilize AOT reverse micelles. A detailed thermodynamic study showed that the driving force for the formation of the reverse micelles is entropy.

  17. Effect of calcium chelators on physical changes in casein micelles in concentrated micellar casein solutions

    NARCIS (Netherlands)

    Kort, de E.J.P.; Minor, M.; Snoeren, T.H.M.; Hooijdonk, van A.C.M.; Linden, van der E.

    2011-01-01

    The effect of calcium chelators on physical changes of casein micelles in concentrated micellar casein solutions was investigated by measuring calcium-ion activity, viscosity and turbidity, and performing ultracentrifugation. The highest viscosities were measured on addition of sodium

  18. Molecular dynamics simulation and NMR investigation of the association of the β-blockers atenolol and propranolol with a chiral molecular micelle

    Science.gov (United States)

    Morris, Kevin F.; Billiot, Eugene J.; Billiot, Fereshteh H.; Hoffman, Charlene B.; Gladis, Ashley A.; Lipkowitz, Kenny B.; Southerland, William M.; Fang, Yayin

    2015-08-01

    Molecular dynamics simulations and NMR spectroscopy were used to compare the binding of two β-blocker drugs to the chiral molecular micelle poly-(sodium undecyl-(L)-leucine-valine). The molecular micelle is used as a chiral selector in capillary electrophoresis. This study is part of a larger effort to understand the mechanism of chiral recognition in capillary electrophoresis by characterizing the molecular micelle binding of chiral compounds with different geometries and charges. Propranolol and atenolol were chosen because their structures are similar, but their chiral interactions with the molecular micelle are different. Molecular dynamics simulations showed both propranolol enantiomers inserted their aromatic rings into the molecular micelle core and that (S)-propranolol associated more strongly with the molecular micelle than (R)-propranolol. This difference was attributed to stronger molecular micelle hydrogen bonding interactions experienced by (S)-propranolol. Atenolol enantiomers were found to bind near the molecular micelle surface and to have similar molecular micelle binding free energies.

  19. Fluorescence dynamics of green fluorescent protein in AOT reversed micelles

    NARCIS (Netherlands)

    Uskova, M.A.; Borst, J.W.; Hink, M.A.; Hoek, van A.; Schots, A.; Klyachko, N.L.; Visser, A.J.W.G.

    2000-01-01

    We have used the enhanced green fluorescent protein (EGFP) to investigate the properties of surfactant-entrapped water pools in organic solvents (reversed micelles) with steady-state and time-resolved fluorescence methods. The surfactant used was sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and the

  20. Insight into the modulation of Shaw2 Kv channels by general anesthetics: structural and functional studies of S4-S5 linker and S6 C-terminal peptides in micelles by NMR.

    Science.gov (United States)

    Zhang, Jin; Qu, Xiaoguang; Covarrubias, Manuel; Germann, Markus W

    2013-02-01

    The modulation of the Drosophila Shaw2 Kv channel by 1-alkanols and inhaled anesthetics is correlated with the involvement of the S4-S5 linker and C-terminus of S6, and consistent with stabilization of the channel's closed state. Structural analysis of peptides from S4-S5 (L45) and S6 (S6c), by nuclear magnetic resonance and circular dichroism spectroscopy supports that an α-helical conformation was adopted by L45, while S6c was only in an unstable/dynamic partially folded α-helix in dodecylphosphocholine micelles. Solvent accessibility and paramagnetic probing of L45 revealed that L45 lies parallel to the surface of micelles with charged and polar residues pointing towards the solution while hydrophobic residues are buried inside the micelles. Chemical shift perturbation introduced by 1-butanol on residues Gln320, Thr321, Phe322 and Arg323 of L45, as well as Thr423 and Gln424 of S6c indicates possible anesthetic binding sites on these two important components in the channel activation apparatus. Diffusion measurements confirmed the association of L45, S6c and 1-butanol with micelles which suggests the capability of 1-butanol to influence a possible interaction of L45 and S6c in the micelle environment.

  1. Extraction of lysozyme, alpha-chymotrypsin, and pepsin into reverse micelles formed using an anionic surfactant, isooctane, and water.

    Science.gov (United States)

    Chang, Q; Liu, H; Chen, J

    1994-11-01

    The extraction of lysozyme, alpha-chymotrypsin, and pepsin from buffered salt solutions into reverse micelles was examined at different pH values and surfactant concentrations. The reverse micelles was formed by mixing aqueous buffer supplemented with KCl and an organic phase of isooctane(2,2,4-trimethylpentane), containing the anionic surfactant, Aerosol O. T. (dioctyl ester of sodium sulfosuccinic acid). The technique of dynamic laser scattering was used to measure the size of reverse micelles which were in equilibrium with the aqueous phase. It was found that the size of the reverse micelles decreased with increasing ionic strength but increased with increasing AOT concentration. In the process of extraction, the reverse micelles might have rearranged themselves to host the protein. The sizes of protein-filled and -unfilled reverse micelles were different, and an open equilibrium could be reached between them. Under the extraction conditions, only a small number of micelles were found to contain protein.

  2. Rheology and phase behavior of dense casein micelle dispersions

    Science.gov (United States)

    Bouchoux, A.; Debbou, B.; Gésan-Guiziou, G.; Famelart, M.-H.; Doublier, J.-L.; Cabane, B.

    2009-10-01

    Casein micelle dispersions have been concentrated through osmotic stress and examined through rheological experiments. In conditions where the casein micelles are separated from each other, i.e., below random-close packing, the dispersions have exactly the flow and dynamic properties of the polydisperse hard-sphere fluid, demonstrating that the micelles interact only through excluded volume effects in this regime. These interactions cause the viscosity and the elastic modulus to increase by three orders of magnitude approaching the concentration of random-close packing estimated at Cmax≈178 g/l. Above Cmax, the dispersions progressively turn into "gels" (i.e., soft solids) as C increases, with elastic moduli G' that are nearly frequency independent. In this second regime, the micelles deform and/or deswell as C increases, and the resistance to deformation results from the formation of bonds between micelles combined with the intrinsic mechanical resistance of the micelles. The variation in G' with C is then very similar to that observed with concentrated emulsions where the resistance to deformation originates from a set of membranes that separate the droplets. As in the case of emulsions, the G' values at high frequency are also nearly identical to the osmotic pressures required to compress the casein dispersions. The rheology of sodium caseinate dispersions in which the caseins are not structured into micelles is also reported. Such dispersions have the behavior of associative polymer solutions at all the concentrations investigated, further confirming the importance of structure in determining the rheological properties of casein micelle systems.

  3. Cysteine modified and bile salt based micelles: preparation and application as an oral delivery system for paclitaxel.

    Science.gov (United States)

    Xu, Wei; Fan, Xiaohui; Zhao, Yanli; Li, Lingbing

    2015-04-01

    The aim of the present study is to construct a cysteine modified polyion complex micelles made of Pluronic F127-chitosan (PF127-CS), Pluronic F127-cysteine (PF127-cysteine) and sodium cholate (NaC) and to evaluate the potential of the micelles as an oral drug delivery system for paclitaxel. Systematic studies on physicochemical properties including size distribution, zeta-potential and morphology were conducted to validate the formation of micelle structure. Compared with Pluronic micelles, drug-loading capacity of PF127-CS/PF127-cysteine/NaC micelles was increased from 3.35% to 12.77%. Both the critical micelle concentration and the stability test confirmed that the PF127-CS/PF127-cysteine/NaC micelles were more stable in aqueous solution than sodium cholate micelles. Pharmacokinetic study demonstrated that when oral administration the area under the plasma concentration-time curve (AUC0-∞) and the absolute bioavailability of paclitaxel-loaded micelles were five times greater than that of the paclitaxel solution. In general, PF127-CS/PF127-cysteine/NaC micelles were proven to be a potential oral drug delivery system for paclitaxel.

  4. Folding of DsbB in mixed micelles

    DEFF Research Database (Denmark)

    Otzen, Daniel

    2003-01-01

    is sensitive to changes in lipid and detergent composition. As an attempt to overcome this problem, I present a kinetic analysis of the folding of a membrane protein, disulfide bond reducing protein B (DsbB), in a mixed micelle system consisting of varying molar ratios of sodium dodecyl sulfate (SDS...... data are always open to alternative interpretations, time-resolved studies in mixed micelles provide a useful approach to measure membrane protein stability over a wide range of concentrations of SDS and DM, as well as a framework for the future characterization of the DsbB folding mechanism....

  5. Thermodynamics of Sodium Dodecyl Sulfate (SDS) Micellization: An Undergraduate Laboratory Experiment

    Science.gov (United States)

    Marcolongo, Juan P.; Mirenda, Martin

    2011-01-01

    An undergraduate laboratory experiment is presented that allows a thermodynamic characterization of micelle formation of sodium dodecyl sulfate (SDS) in aqueous solutions. The critical micelle concentration (CMC) and the degree of micelle ionization (alpha) are obtained at different temperatures by conductimetry. The molar standard free energy…

  6. Micelle structural studies on oil solubilization by a small-angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Putra, Edy Giri Rachman [Neutron Science Division, HANARO Center, Korea Atomic Energy Research Institute (KAERI), 1045 Daedok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Neutron Scattering Laboratory, National Nuclear Energy Agency of Indonesia (BATAN), Gedung 40 Kawasan Puspiptek Serpong, Tangerang 15314 (Indonesia)], E-mail: giri@batan.go.id; Seong, Baek Seok [Neutron Science Division, HANARO Center, Korea Atomic Energy Research Institute (KAERI), 1045 Daedok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Ikram, Abarrul [Neutron Scattering Laboratory, National Nuclear Energy Agency of Indonesia (BATAN), Gedung 40 Kawasan Puspiptek Serpong, Tangerang 15314 (Indonesia)

    2009-02-21

    A small-angle neutron scattering (SANS) technique was applied to reveal the micelle structural changes. The micelle structural changes of 0.3 M sodium dodecyl sulfate (SDS) concentration by addition of various oil, i.e. n-hexane, n-octane, and n-decane up to 60% (v/v) have been investigated. It was found that the size, aggregation number and the structures of the micelles changed exhibiting that the effective charge on the micelle decreases with an addition of oil. There was a small increase in minor axis of micelle while the correlation peak shifted to a lower momentum transfer Q and then to higher Q by a further oil addition.

  7. 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 micellar enzymo

  8. Enzyme recovery using reversed micelles.

    NARCIS (Netherlands)

    Dekker, M.

    1990-01-01

    The objective of this study was to develop a liquid-liquid extraction process for the recovery of extracellular enzymes. The potentials of reaching this goal by using reversed micelles in an organic solvent have been investigated.Reversed micelles are aggregates of surfactant molecules containing an

  9. Sphere-to-rod transition of triblock copolymer micelles at room temperature

    Indian Academy of Sciences (India)

    R Ganguly; V K Aswal; P A Hassan; I K Gopalakrishnan; J V Yakhmi

    2004-08-01

    A room temperature sphere-to-rod transition of the polyethylene oxide-polypropylene oxide-polyethylene oxide-based triblock copolymer, (PEO)20 (PPO)70 (PEO)20 micelles have been observed in aqueous medium under the influence of ethanol and sodium chloride. Addition of 5-10% ethanol induces a high temperature sphere-to-rod transition of the micelles, which is brought to room temperature upon addition of NaCl. The inference about the change in the shape of the micelles has been drawn from small-angle neutron scattering (SANS) and viscosity studies.

  10. Pharmacokinetics and biodistribution of polymeric micelles of paclitaxel with Pluronic P123

    Institute of Scientific and Technical Information of China (English)

    Li-mei HAN; Lie GUO; Li-jun ZHANG; Qing-song WANG; Xiao-ling FANG

    2006-01-01

    Aim: To investigate the preparation, in vitro release, in vivo pharmacokinetics and tissue distribution of a novel polymeric micellar formulation of paclitaxel (PTX) with Pluronic P123. Methods: The polymeric micelles of paclitaxel with Pluronic PI23 were prepared by a solid dispersion method. The characteristics of micelles including particle size distribution, morphology and in vitro release of PTX from micelles were carried out. PTX-loaded micellar solutions were administered through the tail vein to healthy Sprague-Dawley rats and Kunming strain mice to assess the pharmacokinetics and tissue distribution of PTX, respectively. Taxol, the commercially available intravenous formulation of PTX, was also administered as control. Results: By using a dynamic light scattering sizer and a transmission electron microscopy, it was shown that the PTX-loaded micelles had a mean size of approximately 25 nm with narrow size distribution and a spherical shape. PTX was continuously released from Pluronic PI23 micelles in release medium containing 1 mol/L sodium salicylate for 24 h at 37℃. In the pharmacokinetic assessment, t1/2β and AUC of micelle formulation were 2.3 and 2.9-fold higher than that of Taxol injection. And the PTX-loaded micelles increased the uptake of PTX in the plasma, ovary and uterus, lung, and kidney, but decreased uptake in the liver and brain in the biodistribution study. Conclusion: Polymeric micelles using Pluronic P123 can effectively solubilize PTX, prolong blood circulation time and modify the biodistribution of PTX.

  11. Supercritical fluid reverse micelle separation

    Science.gov (United States)

    Fulton, John L.; Smith, Richard D.

    1993-01-01

    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.

  12. 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.

  13. Effect of concentration on surfactant micelle shapes--A molecular dynamics study

    Institute of Scientific and Technical Information of China (English)

    GAO Jian; GE Wei; LI Jinghai

    2005-01-01

    Many aspects of the behavior of surfactants have not been well understood due to the coupling of many different mechanisms. Computer simulation is, therefore, attractive in the sense that it can explore the effect of different mechanisms separately. In this paper, the shapes, structures and sizes of sodium dodecylbenzenesulfonate (SDBS) micelles under different concentrations in an oil/water mixture were studied via molecular dynamics (MD) simulations using a simplified atomistic model which basically maintains the hydrophile and lipophile properties of the surfactant molecules. Above the critical micellar concentration (cmc), surfactant molecules aggregate spontaneously to form a wide variety of assemblies, from spherical to rodlike, wormlike and bilayer micelles. Changes in their ratios of the principle moments of inertia (g1/g3, g2/g3) indicated the transition of micelle shapes at different concentrations. The aggregation number of micelle is found to have a power-law dependence on surfactant concentration.

  14. Effect of substitution on aniline in inducing growth of anionic micelles

    Indian Academy of Sciences (India)

    Gunjan Garg; V K Aswal; S K Kulshreshtha; P A Hassan

    2004-08-01

    Small-angle neutron scattering (SANS) measurements were carried out on sodium dodecyl sulfate (SDS) micelles in the presence of three different hydrophobic salts, i.e. aniline hydrochloride, -toluidine hydrochloride and -toluidine hydrochloride. All these salts induce a uniaxial growth of micelles to form prolate ellipsoidal structures. A progressive decrease in the surface charge of the micelles was observed with the addition of salts followed by a rapid growth of the micelles. The presence of a methyl substitution at the ortho position of aniline does not alter the growth behavior significantly. However, when the substitution is at meta position micellar growth is favored at lower salt concentration than that is observed for aniline. This can be explained in terms of the difference in the chemical environments of the substituents at the ortho and meta positions.

  15. Recovery of proteins and amino acids from reverse micelles by dehydration with molecular sieves.

    Science.gov (United States)

    Gupta, R B; Han, C J; Johnston, K P

    1994-09-20

    A new method is presented to precipitate proteins and amino acids from reverse micelles by dehydrating the micelles with molecular sieves. Nearly complete precipitation is demonstrated for alpha-chymotrypsin, cytochromec, and trytophan from 2-ethylhexyl sodium sulfosuccinate (AOT)/isooctane/water reverse micelle solutions. The products precipitate as a solid powder, which is relatively free of surfactant. The method does not require any manipulation of pH, ionic strength, temperature, pressure, or solvent composition, and is applicable over a broad range of these properties. This general approach is compared with other techniques. This general approach is compared with other techniques for the recovery of biomolecules from reverse micelles. (c) 1994 John Wiley & Sons, Inc.

  16. 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...... > 4 and its mathematical implementation is therefore not straight-forward. It seems as if all of these difficulties can be traced back to the aggregation number. In this work a new principle of data quantification is derived which is easy to apply, interpret and will provide statistical reliable...... 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)...

  17. Formation of Polyion Complex (PIC) Micelles and Vesicles with Anionic pH-Responsive Unimer Micelles and Cationic Diblock Copolymers in Water.

    Science.gov (United States)

    Ohno, Sayaka; Ishihara, Kazuhiko; Yusa, Shin-Ichi

    2016-04-26

    A random copolymer (p(A/MaU)) of sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS) and sodium 11-methacrylamidoundecanate (MaU) was prepared via conventional radical polymerization, which formed a unimer micelle under acidic conditions due to intramolecular hydrophobic interactions between the pendant undecanoic acid groups. Under basic conditions, unimer micelles were opened up to an expanded chain conformation by electrostatic repulsion between the pendant sulfonate and undecanoate anions. A cationic diblock copolymer (P163M99) consisting of poly(3-(methacrylamido)propyl)trimethylammonium chloride (PMAPTAC) and hydrophilic polybetaine, 2-(methacryloyloxy)ethylphosphorylcholine (MPC), blocks was prepared via controlled radical polymerization. Mixing of p(A/MaU) and P163M99 in 0.1 M aqueous NaCl under acidic conditions resulted in the formation of spherical polyion complex (PIC) micelles and vesicles, depending on polymer concentration before mixing. Shapes of the PIC micelles and vesicles changed under basic conditions due to collapse of the charge balance between p(A/MaU) and P163M99. The PIC vesicles can incorporate nonionic hydrophilic guest molecules, and the PIC micelles and vesicles can accept hydrophobic guest molecules in the hydrophobic core formed from p(A/MaU).

  18. Thermodynamics of hexadecyltrimethylammonium bromide micelle formation

    Science.gov (United States)

    Velikov, A. A.

    2017-07-01

    The thermodynamic parameters for CTAB micelle formation (Δ H, Δ G, Δ S) are calculated at different temperatures. Critical micelle concentrations CMC1 are determined. The possibility of determining CMC2 is demonstrated.

  19. Achieving micelle control through core crystallinity.

    Science.gov (United States)

    Glavas, Lidija; Olsén, Peter; Odelius, Karin; Albertsson, Ann-Christine

    2013-11-11

    We have designed a pathway for controlling the critical micelle concentration and micelle size of polyester-based systems. This was achieved by creating an array of different copolymers with semicrystalline or amorphous hydrophobic blocks. The hydrophobic block was constructed through ring-opening polymerization of ε-caprolactone, L-lactide, and ε-decalactone, either as homopolymers or random copolymers, using PEG as both the initiator and the hydrophilic block. Micelles formed with amorphous cores exhibited considerably higher critical micelle concentrations than those with semicrystalline cores. Micelles with amorphous cores also became larger in size with an increased molecular weight of the hydrophobic bock, in contrast to micelles with semicrystalline cores, which displayed the opposite behavior. Hence, core crystallinity was found to be a potent tool for tailoring micelle properties and thereby facilitating the optimization of drug delivery systems. The introduction of PEG-PεDL also proved to be a valuable asset in the tuning of micelle properties.

  20. Polymer micelles with hydrophobic core and ionic amphiphilic corona. 1. Statistical distribution of charged and nonpolar units in corona.

    Science.gov (United States)

    Lysenko, Evgeny A; Kulebyakina, Alevtina I; Chelushkin, Pavel S; Rumyantsev, Artem M; Kramarenko, Elena Yu; Zezin, Alexander B

    2012-12-11

    Polymer micelles with hydrophobic polystyrene (PS) core and ionic amphiphilic corona from charged N-ethyl-4-vinylpyridinium bromide (EVP) and uncharged 4-vinylpyridine (4VP) units spontaneously self-assembled from PS-block-poly(4VP-stat-EVP) macromolecules in mixed dimethylformamide/methanol/water solvent. The fraction of statistically distributed EVP units in corona-forming block is β = [EVP]/([EVP]+[4VP]) = 0.3-1. Micelles were transferred into water via dialysis technique, and pH was adjusted to 9, where 4VP is insoluble. Structural characteristics of micelles were investigated both experimentally and theoretically as a function of corona composition β. Methods of dynamic and static light scattering, electrophoretic mobility measurements, sedimentation velocity, transmission electron microscopy, and UV spectrophotometry were applied. All micelles possessed spherical morphology. The aggregation number, structure, and electrophoretic mobility of micelles changed in a jumplike manner near β ~ 0.6-0.75. Below and above this region, micelle characteristics were constant or insignificantly changed upon β. Theoretical dependencies for micelle aggregation number, corona dimensions, and fraction of small counterions outside corona versus β were derived via minimization the micelle free energy, taking into account surface, volume, electrostatic, and elastic contributions of chain units and translational entropy of mobile counterions. Theoretical estimations also point onto a sharp structural transition at a certain corona composition. The abrupt reorganization of micelle structure at β ~ 0.6-0.75 entails dramatic changes in micelle dispersion stability in the presence of NaCl or in the presence of oppositely charged polymeric (sodium polymethacrylate) or amphiphilic (sodium dodecyl sulfate) complexing agents.

  1. Formation of wormlike micelles in anionic surfactant AES aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The growth and structure of anionic micelles of sodium dodecyl trioxyethylene sulfate (AES) in the presence 3+of multivalent counterion Al were investigated by means of dynamic rheological methods. It has been obtained by the measurements of shear viscosity, complex viscosity and dynamic moduli, as well as the application of Cox-Merz rule and Cole-Cole plot that wormlike micelle and network structure could be formed in AES/AlCl3 aqueous solutions.The structure was of a character of nonlinear viscoelastic fluid and departure from the simple Maxwell model. The technique of freeze-fracture transmission electron microscopy (FF-TEM) was also used to confirm the formation of this interesting structure.``

  2. 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

  3. Study of the formation and solution properties of worm-like micelles formed using both N-hexadecyl-N-methylpiperidinium bromide-based cationic surfactant and anionic surfactant.

    Directory of Open Access Journals (Sweden)

    Zhihu Yan

    Full Text Available The viscoelastic properties of worm-like micelles formed by mixing the cationic surfactant N-hexadecyl-N-methylpiperidinium bromide (C16MDB with the anionic surfactant sodium laurate (SL in aqueous solutions were investigated using rheological measurements. The effects of sodium laurate and temperature on the worm-like micelles and the mechanism of the observed shear thinning phenomenon and pseudoplastic behavior were systematically investigated. Additionally, cryogenic transmission electron microscopy images further ascertained existence of entangled worm-like micelles.

  4. Porphyrins in Reverse Micelles:the Side-chain Length and the Triplet-state Lifetime

    Institute of Scientific and Technical Information of China (English)

    Jun Hua YU; Yu Xiang WENG; Xue Song WANG; Lei ZHANG; Bao Wen ZHANG; Yi CAO

    2003-01-01

    Using bis(2-ethylhexyl) sodium sulfosuccinate (AOT) as surfactant, two amphiphilic porphyrin terminated with imidazole were studied in AOT/iso-octane/water reverse micelles, intending to mimic the relationship between microenvironments in organism and the amphiphilic properties of porphyrins for photodynamic therapy drugs.

  5. Irreversible structural transitions in mixed micelles of oppositely charged diblock copolymers in aqueous solution

    NARCIS (Netherlands)

    Voets, I.K.; Keizer, de A.; Cohen Stuart, M.A.; Justynska, J.; Schlaad, H.

    2007-01-01

    Using light scattering (titration) measurements, we have shown that micelles can be formed in aqueous solutions of a mixture of poly(4-(2-amino hydrochloride-ethylthio)butylene)-block-poly(ethylene oxide), PAETB(49)-b-PEO212, and poly(4-(2-sodium carboxylate-ethylthio)butylene)-block-poly(ethylene

  6. 十二烷基苯磺酸钠-异辛烷-正辛醇反胶束萃取苦参生物碱的研究%Extraction of Alkaloids in Sophora Flavescens Ait by Reverse Micelle of Sodium Dodecyl Benzene Sulfonate/Isooctane/n-Octanol

    Institute of Scientific and Technical Information of China (English)

    刘小琴; 范华均; 佘旭辉; 张来凤; 王李平

    2012-01-01

    利用阴离子表面活性剂十二烷基苯磺酸钠(SDBS)与溶剂异辛烷和助溶剂正辛醇形成反胶束体系,用于苦参生物碱的萃取分离.研究了pH值、表面活性剂浓度、增溶水量W0、盐种类及浓度等因素对萃取的影响.结果表明:SDBS-异辛烷-正辛醇反胶束体系对苦参生物碱具有良好的选择性和较高萃取率,在pH 5.0,增溶水量W0 25,0.05 mol/L SDBS,0.05 mol/L KCl,室温,萃取时间5 min,反萃取时间20 min的最佳萃取条件下,氧化苦参碱、氧化槐果碱、槐定碱、苦参碱、槐果碱5种生物碱及总生物碱的萃取率和RSD分别在74.1%~87.2%和0.63%~3.0%之间.本方法选择性高,操作简便.%A method of reverse micelle extraction of alkaloids in Sophora Flavescens Ait has been developed using the reverse micelle system of sodium dodecyl benzene sulfonate(SDBS)/isooctane/ n-octanol. The experimental conditions such as pH, water content Wo, extraction time and temperature, the concentration of surfactant and salts were optimized. With the help of high performance liquid chromatography, the results showed that the reverse micelle formed by SDBS, isooctane and n-octanol can more effectively extract alkaloids than others. The optimum extraction conditions were as follows: pH 5. 0, 25 of water content Wo, 0. 05 mol/L of SDBS concentration, 0. 05 mol/L of KC1 concentration, 5 min of forward-extraction time and 20 min of backward-extraction time at room temperature. The method has been applied to separate and purify alkaloids from the extract by water with pressurized microwave-assisted extraction. Under the optimum conditions, the extraction yields of oxymatrine, n-oxysophocarpine, sophoridine, matrine, sophocarpine and total alkaloids in Sophora Flavescens Ait were between 74. 1% and 87. 2%, RSDs of their reproducibility were from 0. 6% to 3. 0%. The method is higher selectivity, and easy to operate.

  7. Dielectric relaxation spectroscopy shows a sparingly hydrated interface and low counterion mobility in triflate micelles.

    Science.gov (United States)

    Lima, Filipe S; Chaimovich, Hernan; Cuccovia, Iolanda M; Buchner, Richard

    2013-08-13

    The properties of ionic micelles are affected by the nature of the counterion. Specific ion effects can be dramatic, inducing even shape and phase changes in micellar solutions, transitions apparently related to micellar hydration and counterion binding at the micellar interface. Thus, determining the hydration and dynamics of ions in micellar systems capable of undergoing such transitions is a crucial step in understanding shape and phase changes. For cationic micelles, such transitions are common with large organic anions as counterions. Interestingly, however, phase separation also occurs for dodecyltrimethylammonium triflate (DTATf) micelles in the presence of sodium triflate (NaTf). Specific ion effects for micellar solutions of dodecyltrimethylammonium chloride (DTAC), bromide (DTAB), methanesulfonate (DTAMs), and triflate (DTATf) were studied with dielectric relaxation spectroscopy (DRS), a technique capable of monitoring hydration and counterion dynamics of micellar aggregates. In comparison to DTAB, DTAC, and DTAMs, DTATf micelles were found to be considerably less hydrated and showed reduced counterion mobility at the micellar interface. The obtained DTATf and DTAMs data support the reported central role of the anion's -CF3 moiety with respect to the properties of DTATf micelles. The reduced hydration observed for DTATf micelles was rationalized in terms of the higher packing of this surfactant compared to that of other DTA-based systems. The decreased mobility of Tf(-) anions condensed at the DTATf interface strongly suggests the insertion of Tf(-) in the micellar interface, which is apparently driven by the strong hydrophobicity of -CF3.

  8. Thermostability of Cromobacterium viscosum lipase in AOT/isooctane reverse micelle.

    Science.gov (United States)

    Talukder, M M R; Zaman, M M; Hayashi, Y; Wu, J C; Kawanishi, T

    2007-04-01

    The thermostability of Cromobacterium viscosum lipase (EC 3.1.1.3) entrapped in AOT (sodium bis-[2-ethylhexyl] sulfosuccinate) reverse micelles was increased by the addition of short-chain polyethylene glycol (PEG 400). Two different approaches were considered: (1) the determination of half-life time and (2) the mechanistic analysis of deactivation kinetics. The half-life of lipase entrapped in AOT/isooctane reverse micelles with PEG 400 at 60 degrees C was 28 h, ninefold higher than that in reverse micelles without PEG 400. The lipase entrapped in both reverse micellar systems followed a series-type deactivation mechanism involving two first-order steps. The deactivation constant for the first step at 60 degrees C in PEG containing reverse micelles was 0.055 h!1, 11-fold lower than that in reverse micelles without PEG, whereas it remained almost constant for the second step. The inactivation energy of the lipase entrapped in reverse micelles with and without PEG 400 was 88.12 and 21.97 kJ/mol, respectively.

  9. Interaction of the antibiotic norfloxacin with ionic micelles: pH-dependent binding.

    Science.gov (United States)

    Muniz, Gabriel Silva Vignoli; Teixeira, Letícia Regina; Louro, Sonia Renaux Wanderley

    2014-11-01

    The interaction of the antimicrobial drug norfloxacin (NFX) with anionic sodium dodecyl sulfate (SDS) and cationic cetyltrimethylammonium bromide (CTAB) micelles was studied using the intrinsic spectroscopic properties of NFX to obtain association constants and molecular modifications. Nonionic Tween(®) 20 micelles were also investigated, but the spectroscopic properties of NFX did not detect interactions with these micelles, and quenching by iodide suggested a weak association constant around 47 M(-1). For SDS and CTAB, UV-Vis absorption spectroscopy, steady-state and time-resolved fluorometry were monitored as a function of surfactant concentration ranging from the premicellar to micellar region. It was found that cationic (pH 4.0) and zwitterionic NFX (pH 7.4) associate with SDS micelles, with binding constants equal to 5.4 × 10(3) and 1.7 × 10(3) M(-1), respectively. Premicellar interaction slightly decreases the critical micelle concentration of SDS. Association of anionic NFX (pH 10.6) is very weak. The fluorescence spectrum and lifetime showed that SDS-associated NFX is cationic and that the heterocycle penetrates the interfacial environment of decreased polarity. Cationic CTAB micelles do not bind cationic NFX, and the association constant with zwitterionic NFX is two orders of magnitude lower than that of SDS micelles. From a pharmacological point of view, it is important that at neutral pH, NFX presented a two orders of magnitude higher affinity for anionic than for cationic sites, and did not interact significantly with nonionic or zwitterionic micelle interfaces.

  10. Solute partitioning in aqueous surfactant assemblies: comparison of hydrophobic-hydrophilic interactions in micelles, alcohol-swollen micelles, microemulsions, and synthetic vesicles

    Energy Technology Data Exchange (ETDEWEB)

    Russell, J.C.; Whitten, D.G.

    1982-11-03

    The structures of anionic assemblies including sodium lauryl sulfate (SLS) micelles, alcohol-swollen SLS micelles, microemulsions, and vesicles of a mixture of dipalmitoyllecithin and dicetyl phosphate are investigated by using the ground-state complexation of a hydrophilic quencher (methyl viologen) with several hydrophobic fluorescent probes, including surfactant stilbenes and 1,4-diphenylbutadiene. In SLS micelles this complexation can be decreased nearly an order of magnitude by addition of 1-heptanol, indicating that the structure of the micelle can be adjusted from the highly open structure of the pure micelle to a much more closed structure in which hydrophobic solubilizates can be sequestered from hydrophilic reagents bound to the surface. The fluorescence quenching process in anionic vesicles is strongly dependent on temperature; at low temperatures quenching occurs, while at higher temperatures addition of methyl viologen appears to increase the stilbene fluorescence, indicating that the dicationic quencher binds to the vesicle surface, increasing the order of the system. These results indicate that the degree of organization of surfactant systems can be adjusted by simple changes in composition. 33 references.

  11. Kinetics of Oxidation of Glutathione by Micelle Trapped Tris(benzhydroxamatoiron(III

    Directory of Open Access Journals (Sweden)

    B. L. Hiran

    2007-01-01

    Full Text Available Kinetics of the oxidation of glutathione (GSH by micelle Sodium dodecyl sulphate (SDS trapped tris(benzhydroxamatoiron(III (TBH at pH 3.3 and at 298 K has been described. The reaction is first order in TBS and GSH. Increase in pH decreased the rate. Order in H+ is one The reaction between TBH and GSH on micellar surface (Stern layer differs from that occurring in bulk aqueous phase in absence of micelle (SDS. Reactive FeL3 species on micellar surface is FeL2+.

  12. Simultaneous determination of content and related substances in diclofenac sodium injection by micelle capillary electrophoresis%胶束毛细管电泳同时测定双氯芬酸钠注射液的含量及有关物质

    Institute of Scientific and Technical Information of China (English)

    杨直; 林丽琴; 吴好好

    2013-01-01

    Objective: To establish a micelle capillary electrophoresis method for simultaneous determination of di-clofenac sodium content and 1 - (2,6 -dichlorophenyl) - 1,3 -dihydro -2H - indol -2 - one in diclofenac sodium injection. Methods: The analysis was performed on an extended light path (Bubble Cell) bare fused - silica capillary of 75 μm × 72 cm (200 μm of light path ) with sodium dodecyl sulfate ( SDS ) - borate buffer solution ( pH 9. 0) . The injection pressure was 5. 0 kPa for 3 s,the separation voltage was 30 KV and the wavelength of detection was 242 nm. The column temperature was controlled at 30 ℃. Results: Linear calibration curves were obtained when diclofenac sodium ranged in 0. 1498 mg · mL-1 - 1. 498 mg · mL-1 (r = 0. 9999, n = 8) and 1 - (2,6 - dichlorophenyl) -1,3 -dihydro -2H-indol -2 -one ranged between 0. 9210-9. 210 μg · mL-1 (r =0. 9997,n = 8 ) , the LOD of diclofenac sodium and 1 -(2,6- dichlorophenyl) -1,3- dihydro -2H - indol - 2 - one was 0. 25 and 0. 35 μg · mL-1 Respectively. The average recovery was 100.1% for diclofenac sodium and 99. 7% for 1 - (2, 6 - dichlorophenyl) - 1,3 - dihydro -2H - indol -2 - one. The repeatability was 0. 81% for diclofenac sodium and 0. 95 % for 1 - ( 2,6 - dichlorophenyl) -1,3- dihydro -2H - indol - 2 - one. Conclusion: The method is simple, accurate and economic, which is suitable for the determination of diclofenac sodium and 1 - (2,6 -dichlorophenyl) - 1,3 - dihydro -2H - indol -2 - one in diclofenac sodium injection.%目的:建立胶束毛细管电泳法测定双氯芬酸钠注射液的含量以及双氯芬酸杂质A[1-(2,6-二氯苯基)-1,3-二氢-2H-吲哚-2-酮]的含量.方法:采用扩展光程(鼓泡检测池)未涂渍熔融石英毛细管(有效长度:72 cm;内径:75 μm;光程:200 μm);以十二烷基硫酸钠-硼酸盐缓冲液(pH 9.0)为运行缓冲液;压力进样:5.0 kPa(3 s);操作电压:30kV;检测波长:242nm;毛细管柱温:30℃.结果:双氯芬酸钠和1-(2,6-

  13. Molecular Simulation of Reverse Micelles

    Science.gov (United States)

    Chowdhary, Janamejaya; Ladanyi, Branka

    2009-03-01

    Reverse micelles (RM) are surfactant assemblies containing a nanosized water pool dissolved in a hydrophobic solvent. Understanding their properties is crucial for insight into the effect of confinement on aqueous structure, dynamics as well as physical processes associated with solutes in confinement. We perform molecular dynamics simulations for the RM formed by the surfactant Aerosol-OT (AOT) in isooctane (2,2,4-trimethyl pentane) in order to study the effect of reverse micelle size on the aqueous phase. The structure of the RM is quantified in terms of the radial and pair density distributions. Dynamics are studied in terms of the mean squared displacements and various orientational time correlation functions in different parts of the RM so as to understand the effect of proximity to the interface on aqueous dynamics. Shape fluctuations of the RM are also analyzed.

  14. Vapor pressure studies of the solubilization of hydrocarbons by surfactant micelles. Final report, April 1, 1984-December 31, 1984. [Solubilization data for system benzene/sodium octylsulfate/sodium chloride/water at 15/sup 0/, 25/sup 0/, 35/sup 0/ and 45/sup 0/C

    Energy Technology Data Exchange (ETDEWEB)

    Christian, S.D.; Tucker, E.E.

    1985-04-01

    This final report describes vapor pressure studies of the solubilization of hydrocarbons and hydrocarbon derivatives by aqueous micellar solutions. An automated vapor pressure apparatus and a manual apparatus incorporating a mercury-covered sintered-glass disk inlet valve were used to obtain highly precise data for the solubilization of hydrocarbons and aliphatic alcohols into aqueous solutions of the ionic surfactants sodium octylsulfate and n-hexadecylpyridinium chloride (cetylpyridinium chloride). A mass-action model based on a modification of the Poisson distribution equations has been developed and applied to data for the system benzene/sodium octylsulfate/sodium chloride/water at 15/sup 0/, 25/sup 0/, 35/sup 0/, and 45/sup 0/C. An excellent goodness of fit is achieved with the model. Tabulated experimental results (485 sets of activity and concentration data) are included in this report. 12 references, 2 figures.

  15. Ultrasound-Mediated Polymeric Micelle Drug Delivery.

    Science.gov (United States)

    Xia, Hesheng; Zhao, Yue; Tong, Rui

    2016-01-01

    The synthesis of multi-functional nanocarriers and the design of new stimuli-responsive means are equally important for drug delivery. Ultrasound can be used as a remote, non-invasive and controllable trigger for the stimuli-responsive release of nanocarriers. Polymeric micelles are one kind of potential drug nanocarrier. By combining ultrasound and polymeric micelles, a new modality (i.e., ultrasound-mediated polymeric micelle drug delivery) has been developed and has recently received increasing attention. A major challenge remaining in developing ultrasound-responsive polymeric micelles is the improvement of the sensitivity or responsiveness of polymeric micelles to ultrasound. This chapter reviews the recent advance in this field. In order to understand the interaction mechanism between ultrasound stimulus and polymeric micelles, ultrasound effects, such as thermal effect, cavitation effect, ultrasound sonochemistry (including ultrasonic degradation, ultrasound-initiated polymerization, ultrasonic in-situ polymerization and ultrasound site-specific degradation), as well as basic micellar knowledge are introduced. Ultrasound-mediated polymeric micelle drug delivery has been classified into two main streams based on the different interaction mechanism between ultrasound and polymeric micelles; one is based on the ultrasound-induced physical disruption of the micelle and reversible release of payload. The other is based on micellar ultrasound mechanochemical disruption and irreversible release of payload.

  16. Single step purification of lactoperoxidase from whey involving reverse micelles-assisted extraction and its comparison with reverse micellar extraction.

    Science.gov (United States)

    Nandini, K E; Rastogi, Navin K

    2010-01-01

    The extraction of lactoperoxidase (EC 1.11.1.7) from whey was studied using single step reverse micelles-assisted extraction and compared with reverse micellar extraction. The reverse micelles-assisted extraction resulted in extraction of contaminating proteins and recovery of lactoperoxidase in the aqueous phase leading to its purification. Reverse micellar extraction at the optimized condition after forward and backward steps resulted in activity recovery of lactoperoxidase and purification factor of the order of 86.60% and 3.25-fold, respectively. Whereas reverse micelles-assisted extraction resulted in higher activity recovery of lactoperoxidase (127.35%) and purification factor (3.39-fold). The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) profiles also evidenced that higher purification was obtained in reverse micelles-assisted extraction as compared of reverse micellar extracted lactoperoxidase.

  17. Non-spherical micelles in an oil-in-water cubic phase

    DEFF Research Database (Denmark)

    Leaver, M.; Rajagopalan, V.; Ulf, O.

    2000-01-01

    The cubic phase formed between the microemulsion and hexagonal phases of the ternary pentaethylene glycol dodecyl ether (C12E5)-decane-water system and that doped with small amounts of sodium dodecylsulfate (SDS) have been investigated. The presence of discrete oil-swollen micelles in the cubic...... phase, both with and without SDS, was established by NMR self-diffusion. In addition H-2 NMR relaxation experiments have demonstrated that the micelles in the cubic phase are non-spherical, having grown and changed shape upon formation of the cubic phase from the micellar solution. Small angle...... scattering experiments indicate that the lattice parameter for the cubic phase is inconsistent with a simple packing of micelles. Whilst insufficient reflections were observed to establish the space group of the cubic phase uniquely, those that were are consistent with two commonly observed space groups...

  18. Formation of reverse micelles in supercritical carbon dioxide and its thermodynamics

    Institute of Scientific and Technical Information of China (English)

    WEN Zhen; DANG Zhi; ZONG Minhua; ZHU Zhixin

    2007-01-01

    The solubilization behavior of methyl orange as a solvation probe in multiple systems composed of supercritical carbon dioxide,surfactants and co-solvents,is studied.It is coneluded that some surfactants,such as sodium bis-(2-ethylhexyl)sulfosuccinate(AOT)and isooctyl phenol polyethoxylate (TX-10),could form reverse micelles in supercritical carbon dioxide under the action of butanol.The formation of reverse micelles is a spontaneous process thermodynamically.Specifically for the nonionic surfactant TX-10,the formation of reverse micelles is dependent on the entropy increase in the system,while for the anionic surfactant AOT,the micellization is mainly dominated by the increase in enthalpy at higher temperatures,but by the increase in entropy at lower temperatures.

  19. [Preparation and characterization of cucurbitacin B sodium deoxycholate/phospholipid-mixed oral fast dissolving film and antitumor activity study].

    Science.gov (United States)

    Yu, Chao; Xiao, Yun-Zhi; Xun, Ping-Hua; Dai, Ling; Han, Jin; Yuan, Hai-Long

    2014-05-01

    A novel drug delivery system combining oral fast dissolving film with sodium deoxycholate/phospholipid mixed micelles was prepared to increase the absorption of cucurbitacin B that is a poor aqueous solubility substance. Encapsulation efficiency, particle size, zeta potential, polydispersity coefficient, investigated the morphology, disintegration time of oral fast dissolving film and the pharmacodynamic properties of cucurbitacin B sodium deoxycholate/phospholipid-mixed micelles before and after solidified in mice were evaluated and compared. The oral fast dissolving film prepared in this study showed a homogeneous pale yellow and could completely disintegrated in the 30 s. It could meet the requirements of rapidly disintegrating fully. The encapsulation efficiency, particle size, zeta potential, polydispersity coefficient of cucurbitacin B sodium deoxycholate/phospholipid-mixed micelles loaded in oral fast dissolving film were (43.36 +/- 2.12)%, (108.82 +/- 5.2) nm, (-34.18 +/- 1.07) mV, 0.088 +/- 0.012, respectively. The encapsulation efficiency, particle size, zeta potential, polydispersity coefficient of cucurbitacin B sodium deoxycholate/phospholipid-mixed micelles in solution were (41.26 +/- 2.22)%, (181.82 +/- 4.48) nm, (-30.67 +/- 0.81) mV, 0.092 +/- 0.012, respectively. The difference of pharmacodynamics among film of cucurbitacin B-loaded micelles, cucurbitacin B-loaded micelles and free cucurbitacin B in vivo was compared. Solubility of cucurbitacin B loaded in sodium deoxycholate/phospholipid-mixed micelles has also been greatly improved. The tumor inhibition rate of cucurbitacin B loaded in sodium deoxycholate/phospholipid-mixed micelles was significantly improved and did not change significantly before and after solidified. These showed that the sodium deoxycholate/phospholipid-mixed micelles could enhance the antitumor activities of cucurbitacin B and the stability of cucurbitacin B sodium deoxycholate/phospholipid-mixed micelles was improved

  20. Temperature and pressure based NMR studies of detergent micelle phase equilibria.

    Science.gov (United States)

    Alvares, Rohan; Gupta, Shaan; Macdonald, Peter M; Prosser, R Scott

    2014-05-29

    Bulk thermodynamic and volumetric parameters (ΔGmic°, ΔHmic°, ΔSmic°, ΔCp,mic°, ΔVmic°, and Δκmic°) associated with the monomer–micelle equilibrium, were directly determined for a variety of common detergents [sodium n-dodecyl sulfate (SDS), n-dodecyl phosphocholine (DPC), n-dodecyl-β-d-maltoside (DDM), and 7-cyclohexyl-1-heptyl phosphocholine (CyF)] via 1H NMR spectroscopy. For each temperature and pressure point, the critical micelle concentration (cmc) was obtained from a single 1H NMR spectrum at a single intermediate concentration by referencing the observed chemical shift to those of pure monomer and pure micellar phases. This permitted rapid measurements of the cmc over a range of temperatures and pressures. In all cases, micelle formation was strongly entropically favored, while enthalpy changes were all positive, with the exception of SDS, which exhibited a modestly negative enthalpy of micellization. Heat capacity changes were also characteristically negative, while partial molar volume changes were uniformly positive, as expected for an aggregation process dictated by hydrophobic effects. Isothermal compressibility changes were found to be consistent with previous measurements using other techniques. Thermodynamic measurements were also related to spectroscopic studies of topology and micelle structure. For example, paramagnetic effects resulting from the addition of dioxygen provided microscopic topological details concerning the hydrophobicity gradient along the detergent chains within their respective micelles as detected by 1H NMR. In a second example, combined 13C and 1H NMR chemical shift changes arising from application of high pressure, or upon micellization, of CyF provided site-specific details regarding micelle topology. In this fashion, bulk thermodynamics could be related to microscopic topological details within the detergent micelle.

  1. Direct Measurement of the Thermodynamics of Chiral Recognition in Bile Salt Micelles.

    Science.gov (United States)

    Anderson, Shauna L; Rovnyak, David; Strein, Timothy G

    2016-04-01

    Isothermal titration calorimetry (ITC) is shown to be a sensitive reporter of bile salt micellization and chiral recognition. Detailed ITC characterization of bile micelle formation as well as the chiral recognition capabilities of sodium cholate (NaC), deoxycholate (NaDC), and taurodeoxycholate (NaTDC) micelle systems are reported. The ΔH(demic) of these bile salt micelle systems is directly observable and is strongly temperature-dependent, allowing also for the determination of ΔCp(demic). Using the pseudo-phase separation model, ΔG(demic) and TΔS(demic) were also calculated. Chirally selective guest-host binding of model racemic compounds 1,1'-bi-2-napthol (BN) and 1,1'-binaphthyl-2,2'-diylhydrogenphosphate (BNDHP) to bile salt micelles was then investigated. The S-isomer was shown to bind more tightly to the bile salt micelles in all cases. A model was developed that allows for the quantitative determination of the enthalpic difference in binding affinity that corresponds to chiral selectivity, which is on the order of 1 kJ mol(-1).

  2. A Self-Assembled Nano-Structrured Peroxidase Based on Sodium Dodecyl Sulfate Nano-Micelle and Cytochrome c%十二烷基磺酸钠纳米胶团-细胞色素c自组装高效纳米结构过氧化物酶

    Institute of Scientific and Technical Information of China (English)

    黄琨; 洪军; 王玮; 肖保林; 赵莹雪; 杨卫云; 高云飞

    2012-01-01

    用阴离子表面活性剂十二烷基磺酸钠与细胞色素c自组装的方法构建了一种纳米超分子结构,观察到其具有显著的过氧化物酶活性,且在pH为10.5时达到最高.这种纳米结构过氧化物酶的催化效率为0.0219μmol/L·s.电化学方法测得其电子传递速率常数ks为0.586 s-1.这种以自组装方法构建的超分子结构不仅具有较高活性,可在天然过氧化物酶自杀性失活底物浓度较高时运用,且可固定化于电极上,实现与电极间的直接电子传递.%A nano-structured supermolecule or artificial enzyme was built self-assembly based on sodium dodecyl sulfate nano-micelle and cytochrome c. A significant peroxidase activity was observed and reached the maximum value at pH 10.5. Its catalytic efficiency was evaluated to be 0.0219 μmol/L·s. The immobilized nano-structured peroxidase modified electrode showed quasi-reversible electrochemical redox behaviors with a formal potential of (-38 ± 5) mV (vs. Ag/AgCI) at a scan rate of 0.05 V/s. The cathodic transfer coefficient and electron transfer rate constant were evaluated to be 0.51 and 0.59 s-1 respectively. The apparent Michaelis-Menten constant (Kmapp) was calculated to be 0.14 mmol/L. These results suggest that the nano-structured peroxidase not only perform a high activity as peroxidase and can be used in high concentration of hydrogen peroxide,but also can be immobilized on the electrode and realize direct electrochemical behavior.

  3. Stable Polymer Micelles Formed by Metal Coordination

    NARCIS (Netherlands)

    Wang, Junyou; Stuart, Martien A. Cohen; Marcelis, Antonius T. M.; Colomb-Delsuc, Mathieu; Otto, Sijbren; van der Gucht, Jasper

    2012-01-01

    Metal-containing polymer micelles have attracted much attention due to their potential for medical and nanotechnological applications. In this paper, we present a method to prepare stable metal-containing polymer micelles. A diblock copolymer poly(4-vinylpyridine)-b-poly(ethylene oxide) (P4VP(48)-b-

  4. Synthesis of photolabile fluorescent polymeric micelles.

    Science.gov (United States)

    Park, Teahoon; You, Jungmok; Oikawa, Hidetoshi; Kim, Eunkyoung

    2014-11-01

    A new amphiphilic block copolymers were synthesized with the atom transfer radical polymerization (ATRP) method. Then, the micelle structures were fabricated with a self-assembly method for application in nanocarriers and sensing. The fluorescent intensity was increased by a factor of 4 in the micelle solution due to more stacked pyrene moieties. The core-shell structure of the micelle was confirmed by HR-TEM images. The pyrene moieties were positioned in the core of the micelle, and the surface consisted of hydrophilic PMMA blocks. The ester bond of the polymer backbone was breakable by irradiation with UV light. Therefore, the micelle structure was deformed after UV irradiation, and the excimer peak was drastically reduced as the monomer peak appeared. The deformation of micelle structures was clearly confirmed by FE-SEM and NMR analysis. These photolabile polymeric micelles may be widely useful for photo-stimulative nanocarriers as well as for the design of new functional micelles with many other chromophores.

  5. Formation of micelles with complex coacervate cores.

    NARCIS (Netherlands)

    Cohen Stuart, M.A.; Besseling, N.A.M.; Fokkink, R.G.

    1998-01-01

    Micelles are commonly regarded as colloidal structures spontaneously formed by amphiphilic molecules, that is, molecules consisting of two distinct parts of which one is soluble and the other is insoluble. This definition is too restrictive: other kinds of molecules can also form micelles. We report

  6. Comparison of bile salt/phosphatidylcholine mixed micelles in solubilization to sterols and stability.

    Science.gov (United States)

    Guo, Qin; Cai, Jie; Li, Pengyu; Xu, Dongling; Ni, Xiaomin; Wen, Hui; Liu, Dan; Lin, Suizhen; Hu, Haiyan

    2016-01-01

    Androst-3β,5α,6β-triol (Triol) is a promising neuroprotective agent, but its poor solubility restricts its development into parenteral preparations. In this study, Triol is significantly solubilized by bile salt/phosphatidylcholine mixed micelles (BS/PC-MM). All BS/PC-MM systems are tested to remarkably improve the drug solubility with various stabilities after drug loading. Among them, the sodium glycocholate (SGC)/egg phosphatidylcholine (EPC) system with 2:1 ratio in weight and the total concentration of SGC and EPC of 100 mg/mL is proved to produce stable mixed micelles with high drug loading. It is found that the stability of drug-loaded mixed micelles is quite different, which might be related to the change in critical micelle concentration (CMC) after incorporating drugs. SGC/EPC and SGC/soya phosphatidylcholine (SPC) remain transparent under accelerated conditions and manifest a decreased CMC (dropping from 0.105 to 0.056 mg/mL and from 0.067 to 0.024 mg/mL, respectively). In contrast, swine bile acid-sodium salt (SBA-Na)/PC and sodium deoxycholate (SDC)/PC are accompanied by drug precipitation and reached the maximum CMC on the first and the third days, respectively. Interestingly, the variation of CMC under accelerated testing conditions highly matches the drug-precipitating event in the primary stability experiment. In brief, the bile salt/phosphatidylcholine system exists as a potential strategy of improving sterol drug solubility. CMC variation under accelerated testing conditions might be a simple and easy method to predict the stability of drug-loaded mixed micelles.

  7. Exploring the potential of self-assembled mixed micelles in enhancing the stability and oral bioavailability of an acid-labile drug.

    Science.gov (United States)

    Zhang, Xingwang; Wang, Huan; Zhang, Tianpeng; Zhou, Xiaotong; Wu, Baojian

    2014-10-01

    Oral delivery of many drugs is plagued with limited solubility and/or poor stability. This paper aimed to explore the performance of polymeric mixed micelles on solubilization, stabilization and bioavailability enhancement with stiripentol as model drug. Stiripentol-loaded mixed micelles were prepared by solvent-diffusion method: rapid dispersion of an ethanol solution containing stiripentol, monomethoxy poly(ethylene glycol)-b-poly(ε-caprolactone) and sodium oleate into water. Stiripentol micelles were characterized by the particle size, entrapment efficiency, in vitro drug release, TEM, DSC and FTIR. The pharmacokinetic profile of stiripentol was determined in rats after oral administration of stiripentol micelles. The obtained stiripentol micelles were 44.2 nm in size with an entrapment efficiency over 90%. It was shown that micelles substantially improved the solubility and gastric stability of stiripentol. The oral absorption of stiripentol was also enhanced to a great extent with a relative bioavailability of 157% and 444% to the commercial formulation (Diacomit®) and in-house suspensions. Mixed micelles assembled by di-block copolymer/sodium oleate exhibited a good potential in the improvement of drug stability and bioavailability. It should be a promising carrier for oral delivery of therapeuticals with solubility and stability issues.

  8. Micelle-bound structures and dynamics of the hinge deleted analog of melittin and its diastereomer: implications in cell selective lysis by D-amino acid containing antimicrobial peptides.

    Science.gov (United States)

    Saravanan, Rathi; Bhunia, Anirban; Bhattacharjya, Surajit

    2010-02-01

    Melittin, the major component of the honey bee venom, is a 26-residue hemolytic and membrane active peptide. Structures of melittin determined either in lipid environments by NMR or by use of X-ray demonstrated two helical regions at the N- and C-termini connected by a hinge or a bend at the middle. Here, we show that deletion of the hinge residues along with two C-terminal terminal Gln residues (Q25 and Q26), yielding a peptide analog of 19-residue or Mel-H, did not affect antibacterial activity but resulted in a somewhat reduced hemolytic activity. A diastereomer of Mel-H or Mel-(d)H containing d-amino acids [(d)V5, (d)V8, (d)L11 and (d)K16] showed further reduction in hemolytic activity without lowering antibacterial activity. We have carried out NMR structures, dynamics (H-D exchange and proton relaxation), membrane localization by spin labeled lipids, pulse-field-gradient (PFG) NMR and isothermal titration calorimetry (ITC) in dodecylphosphocholine (DPC) micelles, as a mimic to eukaryotic membrane, to gain insights into cell selectivity of these melittin analogs. PFG-NMR showed Mel-H and Mel-(d)H both were similarly partitioned into DPC micelles. ITC demonstrated that Mel-H and Mel-(d)H interact with DPC with similar affinity. The micelle-bound structure of Mel-H delineated a straight helical conformation, whereas Mel-(d)H showed multiple beta-turns at the N-terminus and a short helix at the C-terminus. The backbone amide-proton exchange with solvent D(2)O demonstrated a large difference in dynamics between Mel-H and Mel-(d)H, whereby almost all backbone protons of Mel-(d)H showed a much faster rate of exchange as compared to Mel-H. Proton T(1) relaxation had suggested a mobile backbone of Mel-(d)H peptide in DPC micelles. Resonance perturbation by paramagnetic lipids indicated that Mel-H inserted deeper into DPC micelles, whereas Mel-(d)H is largely located at the surface of the micelle. Taken together, results presented in this study demonstrated that the

  9. Polar Solvents Trigger Formation of Reverse Micelles.

    Science.gov (United States)

    Khoshnood, Atefeh; Firoozabadi, Abbas

    2015-06-09

    We use molecular dynamics simulations and molecular thermodynamics to investigate the formation of reverse micelles in a system of surfactants and nonpolar solvents. Since the early observation of reverse micelles, the question has been whether the existence of polar solvent molecules such as water is the driving force for the formation of reverse micelles in nonpolar solvents. In this work, we use a simple coarse-grained model of surfactants and solvents to show that a small number of polar solvent molecules triggers the formation of large permanent aggregates. In the absence of polar molecules, both the thermodynamic model and molecular simulations show that small aggregates are more populated in the solution and larger ones are less frequent as the system evolves over time. The size and shape of reverse micelles depend on the size of the polar core: the shape is spherical for a large core and ellipsoidal for a smaller one. Using the coarse-grained model, we also investigate the effect of temperature and surfactant tail length. Our results reveal that the number of surfactant molecules in the micelle decreases as the temperature increases, but the average diameter does not change because the size of the polar core remains invariant. A reverse micelle with small polar core attracts fewer surfactants when the tail is long. The uptake of solvent particles by a micelle of longer surfactant tail is less than shorter ones when the polar solvent particles are initially distributed randomly.

  10. 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.

  11. 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.

  12. Lysophosphatidylcholine enhances carotenoid uptake from mixed micelles by Caco-2 human intestinal cells.

    Science.gov (United States)

    Sugawara, T; Kushiro, M; Zhang, H; Nara, E; Ono, H; Nagao, A

    2001-11-01

    Despite the interest in the beneficial roles of dietary carotenoids in human health, little is known about their solubilization from foods to mixed bile micelles during digestion and the intestinal uptake from the micelles. We investigated the absorption of carotenoids solubilized in mixed micelles by differentiated Caco-2 human intestinal cells, which is a useful model for studying the absorption of dietary compounds by intestinal cells. The micelles were composed of 1 micromol/L carotenoids, 2 mmol/L sodium taurocholate, 100 micromol/L monoacylglycerol, 33.3 micromol/L fatty acid and phospholipid (0-200 micromol/L). The phospholipid content of micelles had profound effects on the cellular uptake of carotenoids. Uptake of micellar beta-carotene and lutein was greatly suppressed by phosphatidylcholine (PC) in a dose-dependent manner, whereas lysophosphatidylcholine (lysoPC), the lipolysis product of PC by phospholipase A2 (PLA2), markedly enhanced both beta-carotene and lutein uptake. The addition of PLA2 from porcine pancreas to the medium also enhanced the uptake of carotenoids from micelles containing PC. Caco-2 cells could take up 15 dietary carotenoids, including epoxy carotenoids, such as violaxanthin, neoxanthin and fucoxanthin, from micellar carotenoids, and the uptakes showed a linear correlation with their lipophilicity, defined as the distribution coefficient in 1-octanol/water (log P(ow)). These results suggest that pancreatic PLA2 and lysoPC are important in regulating the absorption of carotenoids in the digestive tract and support a simple diffusion mechanism for carotenoid absorption by the intestinal epithelium.

  13. Micelle assisted structural conversion with fluorescence modulation of benzophenanthridine alkaloids

    Science.gov (United States)

    Pradhan, Ankur Bikash; Bhuiya, Sutanwi; Haque, Lucy; Tiwari, Richa; Das, Suman

    2017-01-01

    In this study we have reported the anionic surfactant (Sodium dodecyl sulfate, SDS) driven structural conversion of two benzophenanthridine plant alkaloids namely Chelerythrine (herein after CHL) and Sanguinarine (herein after SANG). Both the alkaloids exist in two forms: the charged iminium and the neutral alkanolamine form. The iminium form is stable at low pH ( 10.1). The fluorescence intensity of the alkanolamine form is much stronger than the iminium form. The iminium form of both the alkaloids remains stable whereas the alkanolamine form gets converted to the iminium form in the SDS micelle environment. The iminium form possesses positive charge and it seems that electrostatic interaction between the positively charged iminium and negatively charged surfactant leads to the stabilization of the iminium form in the Stern layer of the anionic micelle. Whereas the conversion of the alkanolamine form into the iminium form takes place and that can be monitored in naked eye since the iminium form is orange in colour and the alkanolamine form has blue violet emission. Such a detail insight about the photophysical properties of the benzophenanthridine alkaloids would be a valuable addition in the field of alkaloid-surfactant interaction.

  14. 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.

  15. Casein Micelle Dispersions under Osmotic Stress

    OpenAIRE

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

    2009-01-01

    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 press...

  16. Adsorption characteristics of uranyl ions onto micelle surface for treatment of radioactive liquid wastes by micelle enhanced ultrafiltration technique

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K. W.; Choi, W. K.; Jeong, K. H.; Lee, D. K.; Jeong, K. J. [KAERI, Taejon (Korea, Republic of)

    2001-10-01

    The objective of this investigation is to establish the rejection behavior of uranium bearing waste water by micelle enhanced ultrafiltration technique. An extensive experimental investigation was conducted with uranium only and uranium in the presence of electrolyte, utilizing ultrasfiltration stirred cell. The effects of experimental parameters such as solution pH and concentration of uranium on rejection were examined from the change of micelle concentration. The rejection dependence of the uranium was found to be a function of pH and uranium to surfactant concentration ratio. Over 95% removal was observed at pH 3 {approx} 5 and SDS concentration of 40 mM. In the presence of electrolytes, the rejection of uranium was observed to decrease significantly, the addition of cobalt ion showed more reduction than that obtained by presence of sodium and cesium ions on rejection of uranium. The rejection behavior was explained in terms of apparent distribution constants. The rejection efficiencies of uranyl ions was significantly affected by the chemical species of the given system. For all cases, the rejection was highly dependent on uranium complex species.

  17. Polymeric micelles for acyclovir drug delivery.

    Science.gov (United States)

    Sawdon, Alicia J; Peng, Ching-An

    2014-10-01

    Polymeric prodrug micelles for delivery of acyclovir (ACV) were synthesized. First, ACV was used directly to initiate ring-opening polymerization of ɛ-caprolactone to form ACV-polycaprolactone (ACV-PCL). Through conjugation of hydrophobic ACV-PCL with hydrophilic methoxy poly(ethylene glycol) (MPEG) or chitosan, polymeric micelles for drug delivery were formed. (1)H NMR, FTIR, and gel permeation chromatography were employed to show successful conjugation of MPEG or chitosan to hydrophobic ACV-PCL. Through dynamic light scattering, zeta potential analysis, transmission electron microscopy, and critical micelle concentration (CMC), the synthesized ACV-tagged polymeric micelles were characterized. It was found that the average size of the polymeric micelles was under 200nm and the CMCs of ACV-PCL-MPEG and ACV-PCL-chitosan were 2.0mgL(-1) and 6.6mgL(-1), respectively. The drug release kinetics of ACV was investigated and cytotoxicity assay demonstrates that ACV-tagged polymeric micelles were non-toxic.

  18. Nonionic reverse micelles near the critical point.

    Science.gov (United States)

    Shrestha, Lok Kumar; Shrestha, Rekha Goswami

    2013-01-01

    We report shape, size, and internal cross-sectional structure of diglycerol monomyristate (C₁₄G₂) reverse micelles in n-hexadecane near the critical point using small-angle X-ray scattering (SAXS). Pair-distance distribution function, p(r), which gives structural information in real-space, was obtained by indirect Fourier transformation (IFT) method. The p(r) showed a clear picture of rodlike micelles at higher temperatures well above the critical point (micellar solution phase separates into two immiscible liquids at ~ 48°C). At a fixed surfactant concentration (5% C₁₄G₂), decrease in temperature increases the micellar size monotonously and surprisingly shape of the p(r) curve at 50°C; close to the critical point, mimics the shape of the two dimensional disk-like micelles indicating the onset of critical fluctuations (attractive interactions among rodlike micelles forming a weak network). A similar behavior has been observed with normal micelles in aqueous system near the critical point. When the system is heated to 60°C, shape of the p(r) curve regains rodlike structure. At fixed temperature of 60°C, increase in C₁₄G₂ concentration induced one dimensional micellar growth. Maximum length of micelles increases from ca. 23.5 to 46.0 nm upon increasing concentration from 1 to 12% keeping cross section diameter apparently unchanged at ca. 4.0 nm.

  19. Structure and dynamics of the conserved protein GPI anchor core inserted into detergent micelles.

    Science.gov (United States)

    Chevalier, Franck; Lopez-Prados, Javier; Groves, Patrick; Perez, Serge; Martín-Lomas, Manuel; Nieto, Pedro M

    2006-10-01

    A suitable approach which combines nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations have been used to study the structure and the dynamics of the glycosylphosphatidylinositol (GPI) anchor Manalphal-2Manalpha1-6Manalphal -4GlcNalpha1-6myo-inositol-1-OPO(3)-sn-1,2-dimyristoylglycerol (1) incorporated into dodecylphosphatidylcholine (DPC) micelles. The results have been compared to those previously obtained for the products obtainable from (1) after phospholipase cleavage, in aqueous solution. Relaxation and diffusion NMR experiments were used to establish the formation of stable aggregates and the insertion of (1) into the micelles. MD calculations were performed including explicit water, sodium and chloride ions and using the Particle Mesh Ewald approach for the evaluation of the electrostatic energy term. The MD predicted three dimensional structure and dynamics were substantiated by nuclear overhauser effect (NOE) measurements and relaxation data. The pseudopentasaccharide structure, which was not affected by incorporation of (1) into the micelle, showed a complex dynamic behaviour with a faster relative motion at the terminal mannopyranose unit and decreased mobility close to the micelle. This motion may be better described as an oscillation relative to the membrane rather than a folding event.

  20. 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.

  1. The aqueous catanionic system sodium perfluorooctanoate-dodecyltrimethylammonium bromide at low concentration.

    Science.gov (United States)

    López-Fontán, José Luis; Blanco, Elena; Ruso, Juan M; Prieto, Gerardo; Schulz, Pablo C; Sarmiento, Félix

    2007-08-15

    The interaction between sodium perfluorooctanoate (SPFO) and dodecyltrimethylammonium bromide (DTAB) was studied by several methods and it was found strongly synergistic. Above a mole fraction of SPFO in the surfactant mixture (alpha(SPFO))=0.38, the interaction is repulsive and increases with the content of SPFO in both, the overall mixture and micelles, whereas the interaction is attractive if DTAB is in excess. At alpha(SPFO)=0.38 the low miscibility between hydrocarbon and fluorocarbon is counterbalanced by the electrostatic attraction between the opposite charged head groups, and the micelle composition is ideal (i.e., the mole fraction of SPFO in micelles X(SPFO)=alpha(SPFO)=0.38). The solubility of fluorocarbon in hydrocarbon is lower than that of hydrocarbon in fluorocarbon. Micelles of DTAB act as a solvent for SPFO without important structural changes, whilst micelles of SPFO undergo important changes when dissolve DTAB. This asymmetry may be interpreted as caused by the difference in chain length that favors the inclusion of the shorter chain in micelles of the longer surfactant, but disfavors the opposite process. Above X(SPFO)=0.5 there is an excess adsorption of bromide ions on the mixed micelles surface, giving rise to a high zeta potential. Micelles of pure SPFO or pure DTAB show an important energy barrier which prevents micelle flocculation. The inclusion of SPFO in DTAB micelles produces a reduction of the energy barrier, which disappeared when alpha(SPFO)=0.5. This produces the flocculation of micelles giving rise to the formation of a non-birefringent coacervate, which is probably formed by unordered isometric clusters of micelles.

  2. Molecular Exchange in Ordered Diblock Copolymer Micelles

    Science.gov (United States)

    Choi, Soo-Hyung; Lodge, Timothy; Bates, Frank

    2011-03-01

    Previously, molecular exchange between spherical micelles in dilute solution (1 vol% polymer) was investigated using time-resolved small-angle neutron scattering (TR-SANS). As the concentration of spherical micelles formed by the diblock copolymers increases, the micelles begin to overlap and eventually pack onto body-centered cubic (BCC) lattice. In this study, concentrated, ordered micelles (15 vol% polymers) prepared by dispersing isotopically labeled poly(styrene- b -ethylene-alt-propylene) in an isotopic squalane mixture was investigated to understand the micellar concentration dependence of the molecular exchange. Perfectly random mixing of isotopically labeled micelles on the BCC lattice was confirmed by SANS patterns where the interparticle contribution vanishes, resulting in an intensity that directly relates to the exchange kinetics. The measured molecular exchange process for the concentrated, ordered system is qualitatively consistent with the previous observations, but the rate is more than an order of magnitude slower than that for the dilute, disordered system. Infineum(IPrime), MRSEC(NSF), NIST.

  3. MOLECULAR THERMODYNAMICS OF MICELLIZATION: MICELLE SIZE DISTRIBUTIONS AND GEOMETRY TRANSITIONS

    Directory of Open Access Journals (Sweden)

    M. S. Santos

    Full Text Available Abstract Surfactants are amphiphilic molecules that can spontaneously self-assemble in solution, forming structures known as micelles. Variations in temperature, pH, and electrolyte concentration imply changes in the interactions between surfactants and micelle stability conditions, including micelle size distribution and micelle shape. Here, molecular thermodynamics is used to describe and predict conditions of micelle formation in surfactant solutions by directly calculating the minimum Gibbs free energy of the system, corresponding to the most stable condition of the surfactant solution. In order to find it, the proposed methodology takes into account the micelle size distribution and two possible geometries (spherical and spherocylindrical. We propose a numerical optimization methodology where the minimum free energy can be reached faster and in a more reliable way. The proposed models predict the critical micelle concentration well when compared to experimental data, and also predict the effect of salt on micelle geometry transitions.

  4. Efficient deacylation of N-acylimidazoles by functionalized surfactant micelles

    OpenAIRE

    Ihara, Yasuji; Nango, Mamoru; Koga, Joichi; ナンゴ, マモル; 南後, 守

    1989-01-01

    Hydroxylated surfactant micelles are powerful catalysts for the deacylation of N-acylimidazoles under neutral conditions; the deacylation rates of hydrophobia acylimidazoles are accelerated remarkably by functionalized micelles containing three hydroxy groups at the polar head.

  5. 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.

  6. 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.

  7. Mechanism of Molecular Exchange in Copolymer Micelles

    Science.gov (United States)

    Choi, Soo-Hyung; Lodge, Timothy; Bates, Frank

    2010-03-01

    Compared to thermodynamic structure, much less has been known about the kinetics of block copolymer micelles which should underlay the attainment of thermodynamic equilibrium. In this presentation, molecular exchange between spherical micelles formed by isotopically labeled diblock copolymers was investigated using time-resolved small-angle neutron scattering. Two pairs of structurally matched poly(styrene-b-ethylene-alt-propylene) (PS-PEP) were synthesized and dispersed in isotopic mixture of squalane, highly selective to PEP block. Each pair includes polymers with fully deuterated (dPS-PEP) and a normal (hPS-PEP) PS blocks. Temperature dependence of the micelle exchange rate R(t) is consistent with melt dynamics for the core polymer. Furthermore, R(t) is significantly sensitive to the core block length N due to the thermodynamic penalty associated with ejecting a core block into the solvent. This hypersensitivity, combined with modest polydispersity in N, leads to an approximately logarithmic decay in R(t).

  8. Coal desulfurization through reverse micelle biocatalysis process

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.; Yen, T.F.

    1988-01-01

    A novel bioprocess using micelle biocatalysis has been attempted to minimize several disadvantages of conventional microbial coal desulfurization scale-up processes. The reverse micelle biocatalysis process consists of a water-immiscible organic medium, a surfactant, an aqueous phase and sulfur-oxidizing bacteria or enzymes. This process has been successful for removing sulfur from bituminous coal (Illinois coal 5). The preliminary results showed that coal desulfurization through the use of cell-free enzyme extracts of Thiobacillus ferrooxidans ATCC 19859 was better than that of bacteria itself. The use of enzymes has shown potential for commercial coal desulfurization process as well. This same process is being applied to the thermophillic bacteria Sulfolobus acidocaldarius ATCC 33909. The implications of these experimental results are discussed, including a hypothetical mechanism using reverse micelle biocatalytical process for coal desulfurization.

  9. Salt-induced release of lipase from polyelectrolyte complex micelles

    NARCIS (Netherlands)

    Lindhoud, Saskia; de Vries, Renko; Schweins, Ralf; Stuart, Martien A. Cohen; Norde, Willem

    2009-01-01

    With the aim to gain insight into the possible applicability of protein-filled polyelectrolyte complex micelles under physiological salt conditions, we studied the behavior of these micelles as a function of salt concentration. The micelles form by electrostatically driven co-assembly from strong ca

  10. 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.

  11. Statistical crystallography of surface micelle spacing

    Science.gov (United States)

    Noever, David A.

    1992-01-01

    The aggregation of the recently reported surface micelles of block polyelectrolytes is analyzed using techniques of statistical crystallography. A polygonal lattice (Voronoi mosaic) connects center-to-center points, yielding statistical agreement with crystallographic predictions; Aboav-Weaire's law and Lewis's law are verified. This protocol supplements the standard analysis of surface micelles leading to aggregation number determination and, when compared to numerical simulations, allows further insight into the random partitioning of surface films. In particular, agreement with Lewis's law has been linked to the geometric packing requirements of filling two-dimensional space which compete with (or balance) physical forces such as interfacial tension, electrostatic repulsion, and van der Waals attraction.

  12. Polymeric micelles as carriers of diagnostic agents.

    Science.gov (United States)

    Trubetskoy

    1999-04-01

    This review deals with diagnostic applications of polymeric micelles composed of amphiphilic block-copolymers. In aqueous solutions these polymers spontaneously form particles with diameter 20-100 nm. A variety of diagnostic moieties can be incorporated covalently or non-covalently into the particulates with high loads. Resulting particles can be used as particulate agents for diagnostic imaging using three major imaging modalities: gamma-scintigraphy, magnetic resonance imaging and computed tomography. The use of polyethyleneoxide-diacyllipid micelles loaded with chelated (111)In/Gd(3+) as well as iodine-containing amphiphilic copolymer in percutaneous lymphography and blood pool/liver imaging are discussed as specific examples.

  13. Reduction of protein adsorption to a solid surface by a coating composed of polymeric micelles with a glass-like core

    NARCIS (Netherlands)

    Hofs, B.; Brzozowska, A.; de Keizer, A.; Norde, W.; Stuart, Martien A. Cohen

    2008-01-01

    Adsorption studies by optical reflectometry show that complex coacervate core micelles (C3Ms) composed of poly([4-(2-amino-ethylthio)-butylene]hydrochloride)(49)-block-poly(ethylene oxide)(212) and poly([4-(2carboxy-ethylthio)-butylene] sodium salt)(47)-block-poly(ethylene oxide)(212) adsorb in equa

  14. Spectroscopic studies of interaction of Safranine T with nonionic micelles and mixed micelles.

    Science.gov (United States)

    Chatterjee, Sujan; Bhattacharya, Subhash Chandra

    2006-05-15

    The visible spectra of Safranine T (ST) in micellar solution of Brij 58, Tween 20 and Tween 40 and mixed micellar solution of Brij 58/Tween 20 and Brij 58/Tween 40 indicate formation of 1:1 charge transfer (CT) complex between acceptor ST and donor nonionic micelles and mixed micelles. The experimental CT transition energies are well correlated (through Mulliken's equation) with the vertical ionization potential of the donors. The solvent parameters, i.e. the intramolecular charge transfer energy ET(30) have been determined from the Stokes spectral shift. Variations of ionization potential and micropolarity in the mixed micellar region have been investigated as a function of surfactant composition and the obtained results in mixed micellar medium has been compared to the normal micelles. The critical micelle concentration (CMC) values determined at various surfactant compositions are lower than the ideal values indicating a synergistic interaction. The interaction parameter (beta) and micellar stability has been calculated using regular solution theory.

  15. Micelle depletion-induced vs. micelle-mediated aggregation in nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-24

    The phase behavior anionic silica nanoparticle (Ludox LS30) with non-ionic surfactants decaethylene glycol monododecylether (C12E10) and cationic dodecyltrimethyl ammonium bromide (DTAB) in aqueous electrolyte solution has been studied by small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations of nanoparticle (1 wt%), surfactants (1 wt%) and electrolyte (0.1 M NaCl). Each of these nanoparticle–surfactant systems has been examined for different contrast conditions where individual components (nanoparticle or surfactant) are made visible. It is observed that the nanoparticle-micelle system in both the cases lead to the aggregation of nanoparticles. The aggregation is found to be micelle depletion-induced for C12E10 whereas micelle-mediated aggregation for DTAB. Interestingly, it is also found that phase behavior of mixed surfactant (C12E10 + DTAB) system is similar to that of C12E10 (unlike DTAB) micelles with nanoparticles.

  16. Structure and physico-chemical properties in mixed aqueoussolution of sodium alkylcarboxylate-alkyltrimethylammoniumbromide

    Institute of Scientific and Technical Information of China (English)

    HUANG, Jian-Bin(黄建滨); ZHAO, Guo-Xi(赵国玺); HE, Xu(何煦); ZHU, Bu-Yao(朱步瑶); FU, Hong-Lan(付宏兰)

    2000-01-01

    The physico-chemical properties of organized assemblies (micelle or vesicle) from sodium alkylcarboxylate-alkyltrimethyl-ammonium bromide mixture have been investigated systematically. In different mixed cationic-anionic surfactant systems, micelles and vesicles can coexist or be transformed into each other on different conditions. The experimental results are explained prelimilarily from the viewpoint of molecular packing geometry. The solubilization of organic compound in the mixed surfactant system was also studied in detail.

  17. Applications of micelle enhancement in luminescence-based analysis.

    Science.gov (United States)

    Alarfaj, Nawal A; El-Tohamy, Maha F

    2015-02-01

    Micelles are self-assembled aggregates that arrange themselves into spheres in aqueous media. When the surfactant concentration reaches the critical micelle concentration, extensive aggregation of the surfactant monomers occurs to form micelles. A micelle has both a hydrophilic and a hydrophobic part. This allows them to form a spherical shape and for their glycolipid and phospholipid components to form lipid bilayers. The importance of micelles is increasing because of their wide analytical applications. Recently, colloidal carrier systems have received much attention in the field of analytical chemistry, especially in luminescence enhancement applications.

  18. Molecular Exchange Dynamics in Block Copolymer Micelles

    Science.gov (United States)

    Bates, Frank; Lu, Jie; Choi, Soohyung; Lodge, Timothy

    2012-02-01

    Poly(styrene-b-ethylene propylene) (PS-PEP) diblock copolymers were mixed with squalane (C30H62) at 1% by weight resulting in the formation of spherical micelles. The structure and dynamics of molecular exchange were characterized by synchrotron small-angle x-ray scattering (SAXS) and time resolved small-angle neutron scattering (TR-SANS), respectively, between 100 C and 160 C. TR-SANS measurements were performed with solutions initially containing deuterium labeled micelle cores and normal cores dispersed in a contrast matched squalane. Monitoring the reduction in scattering intensity as a function of time at various temperatures revealed molecular exchange dynamics highly sensitive to the core molecular weight and molecular weight distribution. Time-temperature superposition of data acquired at different temperatures produced a single master curve for all the mixtures. Experiments conducted with isotopically labeled micelle cores, each formed from two different but relatively mondisperse PS blocks, confirmed a simple dynamical model based on first order kinetics and core Rouse single chain relaxation. These findings demonstrate a dramatic transition to nonergodicity with increasing micelle core molecular weight and confirm the origins of the logarithmic exchange kinetics in such systems.

  19. Chain exchange in block copolymer micelles

    Science.gov (United States)

    Lu, Jie; Bates, Frank; Lodge, Timothy

    2014-03-01

    Block copolymer micelles are aggregates formed by self-assembly of amphiphilic copolymers dispersed in a selective solvent, driven by unfavorable interactions between the solvent and the core-forming block. Due to the relatively long chains being subject to additional thermodynamic and dynamic constraints (e.g., entanglements, crystallinity, vitrification), block copolymer micelles exhibit significantly slower equilibration kinetics than small molecule surfactants. As a result, details of the mechanism(s) of equilibration in block copolymer micelles remain unclear. This present works focuses on the chain exchange kinetics of poly(styrene-b-ethylenepropylene) block copolymers in squalane (C30H62) using time-resolved small angle neutron scattering (TR-SANS). A mixture of h-squalane and d-squalane is chosen so that it contrast matches a mixed 50/50 h/d polystyrene micelle core. When the temperature is appropriate and isotopically labeled chains undergo mixing, the mean core contrast with respect to the solvent decreases, and the scattering intensity is therefore reduced. This strategy allows direct probing of chain exchange rate from the time dependent scattering intensity I(q, t).

  20. POLYMER MICELLE INTERACTIONS - PHYSICAL ORGANIC ASPECTS

    NARCIS (Netherlands)

    BRACKMAN, JC; ENGBERTS, JBFN

    1993-01-01

    This review presents a summary of attempts to characterize the morphology of the complexes formed between ionic and non-ionic surfactants and water-soluble polymers. It is now generally accepted that complex formation involves the binding of micelles to the macromolecule. This binding process modifi

  1. Non-diffusing radiochromic micelle gel

    Science.gov (United States)

    Jordan, Kevin; Sekimoto, Masaya

    2010-11-01

    The addition of Laponite, a synthetic clay nanoparticle material to radiochromic leuco Malachite Green micelle hydrogel eliminates diffusion of the cationic dye by electrostatic binding. The clay nanoparticles also increased dose sensitivity ten-fold relative to the parent gel formulation. This material is a suitable 3D water equivalent dosimeter with optical CT readout.

  2. 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.)

  3. Acid Hydrolysis of Bromazepam Catalyzed by Micelles, Reverse Micelles, and Microemulsions

    Directory of Open Access Journals (Sweden)

    Ferdousi Begum

    2015-01-01

    Full Text Available Kinetics of the acid hydrolysis of bromazepam (Bz has been investigated in micelles, reverse micelles, and microemulcions of cetyltrimethylammonium bromide (CTAB by spectrophotometric method. The rate of the acid hydrolysis of Bz was found to be enhanced both below and above the critical micelle concentration (CMC of CTAB in aqueous solution. The pseudo-first-order rate constant (k′ shows an initial decrease for both low and high H+ concentrations. With further increase in [CTAB], at low [H+], the k′ attains an almost constant value, while, at high [H+], the k′ passes through a maximum and then decreases. The kinetic data for catalysis by micelles of CTAB was interpreted with the pseudophase ion exchange (PIE model. In CTAB/cyclohexane/1-butanol/water microemulsions, as the water to surfactant ratio (wo increases, the physicochemical properties and droplet sizes of microemulsions significantly change and distinct changes in reaction environment can be marked. The rate of the hydrolysis reaction exhibits excellent correlation with the physicochemical properties and droplet sizes of the microemulsions and reverse micelles of CTAB. At [H+] = 0.001 M, in reverse micelles and microemulsions of CTAB, the k′ of the acid hydrolysis of Bz decreases sharply followed by a slight increase with increasing wo.

  4. Delivery of phytochemical thymoquinone using molecular micelle modified poly(D, L lactide-co-glycolide) (PLGA) nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ganea, Gabriela M; Warner, Isiah M [Department of Chemistry, Louisiana State University, 434 Choppin Hall, Baton Rouge, LA 70803 (United States); Fakayode, Sayo O [Department of Chemistry, Anderson Center Modular Unit 244-B, Winston-Salem State University, Winston Salem, NC 27110 (United States); Losso, Jack N [Food Science Department, Louisiana State University Agricultural Center, 111 Food Science Building, Baton Rouge, LA 70803 (United States); Van Nostrum, Cornelus F [Department of Pharmaceutics, Utrecht Institute of Pharmaceutical Sciences (UIPS), Utrecht University, Sorbonnelaan 16, 3508 TB Utrecht (Netherlands); Sabliov, Cristina M, E-mail: iwarner@lsu.edu [Biological and Agricultural Engineering Department, Louisiana State University Agricultural Center, 141 E B Doran Building, Baton Rouge, LA 70803 (United States)

    2010-07-16

    Continuous efforts have been made in the development of potent benzoquinone-based anticancer drugs aiming for improved water solubility and reduced adverse reactions. Thymoquinone is a liposoluble benzoquinone-based phytochemical that has been shown to have remarkable antioxidant and anticancer activities. In the study reported here, thymoquinone-loaded PLGA nanoparticles were synthesized and evaluated for physico-chemical, antioxidant and anticancer properties. The nanoparticles were synthesized by an emulsion solvent evaporation method using anionic molecular micelles as emulsifiers. The system was optimized for maximum entrapment efficiency using a Box-Behnken experimental design. Optimum conditions were found for 100 mg PLGA, 15 mg TQ and 0.5% w/v poly(sodium N-undecylenyl-glycinate) (poly-SUG). In addition, other structurally related molecular micelles such as poly(sodium N-heptenyl-glycinate) (poly-SHG), poly(sodium N-undecylenyl-leucinate) (poly-SUL), and poly(sodium N-undecylenyl-valinate) (poly-SUV) were also examined as emulsifiers. All investigated molecular micelles provided excellent emulsifier properties, leading to maximum optimized TQ entrapment efficiency, and monodispersed particle sizes below 200 nm. The release of TQ from molecular micelle modified nanoparticles was investigated by dialysis and reached lower levels than the free drug. The antioxidant activity of TQ-loaded nanoparticles, indicated by IC50 (mg ml{sup -1} TQ for 50% 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity), was highest for poly-SUV emulsified nanoparticles (0.030 {+-} 0.002 mg ml{sup -1}) as compared to free TQ. In addition, it was observed that TQ-loaded nanoparticles emulsified with poly-SUV were more effective than free TQ against MDA-MB-231 cancer cell growth inhibition, presenting a cell viability of 16.0 {+-} 5.6% after 96 h.

  5. Delivery of phytochemical thymoquinone using molecular micelle modified poly(D, L lactide-co-glycolide) (PLGA) nanoparticles

    Science.gov (United States)

    Ganea, Gabriela M.; Fakayode, Sayo O.; Losso, Jack N.; van Nostrum, Cornelus F.; Sabliov, Cristina M.; Warner, Isiah M.

    2010-07-01

    Continuous efforts have been made in the development of potent benzoquinone-based anticancer drugs aiming for improved water solubility and reduced adverse reactions. Thymoquinone is a liposoluble benzoquinone-based phytochemical that has been shown to have remarkable antioxidant and anticancer activities. In the study reported here, thymoquinone-loaded PLGA nanoparticles were synthesized and evaluated for physico-chemical, antioxidant and anticancer properties. The nanoparticles were synthesized by an emulsion solvent evaporation method using anionic molecular micelles as emulsifiers. The system was optimized for maximum entrapment efficiency using a Box-Behnken experimental design. Optimum conditions were found for 100 mg PLGA, 15 mg TQ and 0.5% w/v poly(sodium N-undecylenyl-glycinate) (poly-SUG). In addition, other structurally related molecular micelles such as poly(sodium N-heptenyl-glycinate) (poly-SHG), poly(sodium N-undecylenyl-leucinate) (poly-SUL), and poly(sodium N-undecylenyl-valinate) (poly-SUV) were also examined as emulsifiers. All investigated molecular micelles provided excellent emulsifier properties, leading to maximum optimized TQ entrapment efficiency, and monodispersed particle sizes below 200 nm. The release of TQ from molecular micelle modified nanoparticles was investigated by dialysis and reached lower levels than the free drug. The antioxidant activity of TQ-loaded nanoparticles, indicated by IC50 (mg ml - 1 TQ for 50% 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity), was highest for poly-SUV emulsified nanoparticles (0.030 ± 0.002 mg ml - 1) as compared to free TQ. In addition, it was observed that TQ-loaded nanoparticles emulsified with poly-SUV were more effective than free TQ against MDA-MB-231 cancer cell growth inhibition, presenting a cell viability of 16.0 ± 5.6% after 96 h.

  6. Casein micelles and their internal structure

    Energy Technology Data Exchange (ETDEWEB)

    De Kruif, Cornelis G [ORNL; Huppertz, Thom [NIZO Food Research; Urban, Volker S [ORNL; Petukhov, Andrei V [Van ' t Hoff laboratory for Physical and Colloid Chemistry, Utrecht University, The Netherlands

    2012-01-01

    The internal structure of casein micelles was studied by calculating the small-angle neutron and X-ray scattering and static light scattering spectrum (SANS, SAXS, SLS) as a function of the scattering contrast and composition. We predicted experimental SANS, SAXS, SLS spectra self consistently using independently determined parameters for composition size, polydispersity, density and voluminosity. The internal structure of the casein micelles, i.e. how the various components are distributed within the casein micelle, was modeled according to three different models advocated in the literature; i.e. the classical sub-micelle model, the nanocluster model and the dual binding model. In this paper we present the essential features of these models and combine new and old experimental SANS, SAXS, SLS and DLS scattering data with new calculations that predict the spectra. Further evidence on micellar substructure was obtained by internally cross linking the casein micelles using transglutaminase, which led to casein nanogel particles. In contrast to native casein micelles, the nanogel particles were stable in 6 M urea and after sequestering the calcium using trisodium citrate. The changed scattering properties were again predicted self consistently. An important result is that the radius of gyration is independent of contrast, indicating that the mass distribution within a casein micelle is homogeneous. Experimental contrast is predicted quite well leading to a match point at a D{sub 2}O volume fraction of 0.41 ratio in SANS. Using SANS and SAXS model calculations it is concluded that only the nanocluster model is capable of accounting for the experimental scattering contrast variation data. All features and trends are predicted self consistently, among which the 'famous' shoulder at a wave vector value Q = 0.35 nm{sup -1}. In the nanocluster model, the casein micelle is considered as a (homogeneous) matrix of caseins in which the colloidal calcium phosphate (CCP

  7. Sodium Test

    Science.gov (United States)

    ... low levels of cortisol, aldosterone and sex hormones ( Addison disease ) Drinking too much water as might occur during ... urinary sodium levels may indicate diuretic use or Addison disease. Sodium levels are often evaluated in relation to ...

  8. Sodium Phosphate

    Science.gov (United States)

    Sodium phosphate is used in adults 18 years of age or older to empty the colon (large intestine, bowel) ... view of the walls of the colon. Sodium phosphate is in a class of medications called saline ...

  9. Sodium Oxybate

    Science.gov (United States)

    Sodium oxybate is used to prevent attacks of cataplexy (episodes of muscle weakness that begin suddenly and ... urge to sleep during daily activities, and cataplexy). Sodium oxybate is in a class of medications called ...

  10. Small angle neutron scattering study of mixed micelles of oppositely charged surfactants

    Indian Academy of Sciences (India)

    J V Joshi; V K Aswal; P S Goyal

    2008-11-01

    Structures of mixed micelles of oppositely charged surfactants dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulphate (SDS) have been studied using small angle neutron scattering. The concentration of one of the components was kept fixed (0.3 M) and that of another varied in the range 0 to 0.1 M. The aggregation number and micellar size increase and fractional charge decreases dramatically with the addition of small amount of oppositely charged surfactant. The effect of addition of SDS on DTAB is significantly different from that of the addition of DTAB on SDS. The contrast variation SANS experiments using deuterated surfactant suggests the homogeneous mixing of two components in mixed micellar system.

  11. Formation and Fluorimetric Characterization of Micelles in a Micro-flow Through System with Static Micro Mixer

    Directory of Open Access Journals (Sweden)

    J. Michael Köhler

    2007-10-01

    Full Text Available The formation and behaviour of micelles of sodium dodecylsulfate in water byuse of a static micro mixer were studied. Trisbipyridylruthenium(II was applied asindicator dye, 9-methylanthracene was used for fluorescence quenching. All experimentswere carried out by a micro fluid arrangement with three syringe pumps, a 2 1 two-stepstatic micro mixer (IPHT Jena and a on-line micro fluorimetry including a luminescencediode for excitation, a blue glass filter (BG 7, Linos, two edge filters (RG 630, Linos anda photo counting module (MP 900, Perkin Elmer. It was possible to measure thefluorescence inside the PTFE tube (inner diameter 0.5 mm directly. A linear dependenceof fluorescence intensity from dye concentration was observed in absence of quencher andsurfactant as expected. An aggregation number of about 62 was found in the flow raterange between 300 and 800 μL/min. The fluorescence intensity increases slightly, butsignificant with increasing flow rate, if no quencher is present. In the presence of quencher,the fluorescence intensity decreases with decreasing surfactant concentration and withenhanced flow rate. The strength of the flow rate effect on the fluorescence increases withdecreasing surfactant concentration. The size of micelles was determined in micro channelsby the micro fluorimetric method in analogy to the conventional system. The micellesextract the quencher from the solution and lower, this way, the quenching effect. The sizeof micelles was estimated and it could be shown, that the flow rate has only low effect onthe aggregation number at the investigated flow rates. The effect of flow rate andsurfactant concentration on the fluorescence in the presence of quencher was interpreted asa shift in the micelle concentration due to the shear forces. It is expected, that thefluorescence intensity is lowered, if more quencher molecules are molecular disperse distributed inside the solution. Obviously, the lowered fluorescence

  12. Catalytic activity of lignin peroxidase and partition of veratryl alcohol in AOT/isooctane/toluene/water reverse micelles.

    Science.gov (United States)

    Zhang, Wenjuan; Huang, Xirong; Li, Yuezhong; Qu, Yinbo; Gao, Peiji

    2006-04-01

    The activity of lignin peroxidase (LiP) and the partition of its optimum substrate veratryl alcohol (VA) in sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane/toluene/water reverse micelles were studied in this paper to understand the microheterogeneous effect of the medium on the catalytic properties of LiP hosted in the reverse micelle. Results showed that LiP from Phanerochaete chrysosporium could express its activity in the reverse micelles, but its activity depended, to a great extent, on the composition of the reverse micelles. Optimum activity occurred at a molar ratio of water to AOT (omega0) of 11, a pH value of 3.6, and a volume ratio of isooctane to toluene of 7-9. Under optimum conditions, the half-life of LiP was circa 12 h. The dependence of LiP activity on the volume fraction of water in the medium (theta), at a constant omega0 value of 11, indicated that VA was mainly solubilized in the pseudophase of the reverse micelle. Based on the pseudobiphasic model and the corresponding kinetic method, a linear line can be obtained in a plot of apparent Michaelis constant of VA vs theta, and the partition coefficient of VA between the pseudophase and the organic solvent phase was determined to be 35.8, which was higher than that (22.3) between bulk water and the corresponding mixed organic solvent. H2O2 inhibited LiP at concentrations higher than 80 microM; this concentration value seems to be different from that in aqueous solution (about 3 mM). The differences mentioned above should be ascribed to the microheterogeneity and the interface of the AOT reverse micelle.

  13. Cation-pi interactions stabilize the structure of the antimicrobial peptide indolicidin near membranes: molecular dynamics simulations

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Kaznessis, Yiannis N

    2007-01-01

    We implemented molecular dynamics simulations of the 13-residue antimicrobial peptide indolicidin (ILPWKWPWWPWRR-NH2) in dodecylphosphocholine (DPC) and sodium dodecyl sulfate (SDS) micelles. In DPC, a persistent cation-pi interaction between TRP11 and ARG13 defined the structure of the peptide...... near the interface. A transient cation-pi interaction was also observed between TRP4 and the choline group on DPC lipids. We also implemented simulation of a mutant of indolicidin in the DPC micelle where TRP11 was replaced by ALA11. As a result of the mutation, the boat-shaped conformation is lost...

  14. Acid-base properties and solubility of pindolol, diazepam and chlordiazepoxide in SDS micelles.

    Science.gov (United States)

    de Castro, B; Domingues, V; Gameiro, P; Lima, J L; Oliveira, A; Reis, S

    1999-09-30

    The effect of sodium dodecyl sulphate (SDS) on the acid-base properties and on the solubility of a beta-blocker (pindolol) and of two benzodiazepines (diazepam and chlordiazepoxide) has been assessed. The study was performed by potentiometric and spectrophotometric determinations of the acidity constants and by spectrophotometric evaluation of the solubilities of the pharmaceutical drugs in aqueous solution and in solutions to which was added SDS with concentrations below and above the critical micelle concentration (cmc), at 25 degrees C and at an ionic strength 0.1 M (NaCl). The effect of the organized assemblies on the pKa values was quantified by the application of two theoretical models that differ in the inclusion of ionic exchange between positively charged species in solution. These models have allowed the determination of the binding constants for drug/micelle and yielded values in good agreement with those obtained by the solubility method, and in addition provide a more detailed picture of the effect of drug charge on its partition. The results can be taken to evidence different interaction modes of the drugs with the SDS micelles.

  15. Preparation and Evaluation of Inhalable Itraconazole Chitosan Based Polymeric Micelles

    Directory of Open Access Journals (Sweden)

    Esmaeil Moazeni

    2012-12-01

    Full Text Available Background: This study evaluated the potential of chitosan based polymeric micelles as a nanocarrier system for pulmonary delivery of itraconazole (ITRA.Methods: Hydrophobically modified chitosan were synthesized by conjugation of stearic acid to the hydrophilic depolymerized chitosan. FTIR and 1HNMR were used to prove the chemical structure and physical properties of the depolymerized and the stearic acid grafted chitosan. ITRA was entrapped into the micelles and physicochemical properties of the micelles were investigated. Fluorescence spectroscopy, dynamic laser light scattering andtransmission electron microscopy were used to characterize the physicochemical properties of the prepared micelles. The in vitro pulmonary profile of polymeric micelles was studied by an air-jet nebulizer connected to a twin stage impinger.Results: The polymeric micelles prepared in this study could entrap up to 43.2±2.27 μg of ITRA per milliliter. All micelles showed mean diameter between 120–200 nm. The critical micelle concentration of the stearic acid grafted chitosan was found to be 1.58×10-2 mg/ml. The nebulization efficiency was up to 89% and the fine particle fraction (FPF varied from 38% to 47%. The micelles had enough stability to remain encapsulation of the drug during nebulization process.Conclusions: In vitro data showed that stearic acid grafted chitosan based polymeric micelles has a potential to be used as nanocarriers for delivery of itraconazole through inhalation.

  16. Preparation of ZrO2 nano-particles by the hydrolysis of ZrOCl2 solution in the reverse micelles

    Institute of Scientific and Technical Information of China (English)

    Chensha Li; Tongxiang Liang; Tianyong Luo

    2006-01-01

    Zirconia nano-particles have been produced by the hydrolysis of ZrOGl2 solution in the reverse micelles of a liquid-liquid two-phase system, in which sodium bis(2-ethylhexyl) sulfosuccinite (AOT) and toluene were chosen as the surfactant and organic phase, respectively. The reverse micelles prevented the aggregation of primary particles and reduced the diameters of zirconia nanoparticles. Superfine zirconia powders soft-aggregated by the zirconia nano-particles were obtained. The diameters of zirconia nanoparticles were influenced by the quantity of the surfactant.

  17. On the stability and morphology of complex coacervate core micelles: from spherical to wormlike micelles.

    Science.gov (United States)

    van der Kooij, Hanne M; Spruijt, Evan; Voets, Ilja K; Fokkink, Remco; Cohen Stuart, Martien A; van der Gucht, Jasper

    2012-10-01

    We present a systematic study of the stability and morphology of complex coacervate core micelles (C3Ms) formed from poly(acrylic acid) (PAA) and poly(N-methyl-2-vinylpyridinium)-b-poly(ethylene oxide) (PM2VP-b-PEO). We use polarized and depolarized dynamic and static light scattering, combined with small-angle X-ray scattering, to investigate how the polymer chain length and salt concentration affect the stability, size, and shape of these micelles. We show that C3Ms are formed in aqueous solution below a critical salt concentration, which increases considerably with increasing PAA and PM2VP length and levels off for long chains. This trend is in good agreement with a mean-field model of polyelectrolyte complexation based on the Voorn-Overbeek theory. In addition, we find that salt induces morphological changes in C3Ms when the PAA homopolymer is sufficiently short: from spherical micelles with a diameter of several tens of nanometers at low salt concentration to wormlike micelles with a contour length of several hundreds of nanometers just before the critical salt concentration. By contrast, C3Ms of long PAA homopolymers remain spherical upon addition of salt and shrink slightly. A critical review of existing literature on other C3Ms reveals that the transition from spherical to wormlike micelles is probably a general phenomenon, which can be rationalized in terms of a classical packing parameter for amphiphiles.

  18. Differential refractometric determination of binding of sodium dodecyl sulfate to protein using high-performance gel chromatography.

    Science.gov (United States)

    Rao, P F; Takagi, T

    1988-10-01

    When sodium dodecyl sulfate (SDS) is added to a high-performance gel chromatographic column equilibrated with a buffer solution containing SDS at a level above the critical micelle concentration, the surplus SDS migrates as micelles giving a sharp peak. The presence of an unfolded protein in the sample solution gives a polypeptide peak in advance of the SDS micelle peak. As the result of SDS binding to the polypeptide, the SDS micelle peak is attenuated in comparison to that in the absence of protein. Thus the amount of SDS bound to the polypeptide can be determined accurately and simply from the decrease in the area of the SDS micelle peak. This approach is particularly useful for precise determination of bound SDS, which is pertinent to understanding the state of the protein polypeptide-SDS complex under the conditions of SDS-polyacrylamide gel electrophoresis.

  19. 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...

  20. Sucrose monoester micelles size determined by Fluorescence Correlation Spectroscopy (FCS.

    Directory of Open Access Journals (Sweden)

    Susana A Sanchez

    Full Text Available One of the several uses of sucrose detergents, as well as other micelle forming detergents, is the solubilization of different membrane proteins. Accurate knowledge of the micelle properties, including size and shape, are needed to optimize the surfactant conditions for protein purification and membrane characterization. We synthesized sucrose esters having different numbers of methylene subunits on the substituent to correlate the number of methylene groups with the size of the corresponding micelles. We used Fluorescence Correlation Spectroscopy (FCS and two photon excitation to determine the translational D of the micelles and calculate their corresponding hydrodynamic radius, R(h. As a fluorescent probe we used LAURDAN (6-dodecanoyl-2-dimethylaminonaphthalene, a dye highly fluorescent when integrated in the micelle and non-fluorescent in aqueous media. We found a linear correlation between the size of the tail and the hydrodynamic radius of the micelle for the series of detergents measured.

  1. Chain exchange in triblock copolymer micelles

    Science.gov (United States)

    Lu, Jie; Lodge, Timothy; Bates, Frank

    2015-03-01

    Block polymer micelles offer a host of technological applications including drug delivery, viscosity modification, toughening of plastics, and colloidal stabilization. Molecular exchange between micelles directly influences the stability, structure and access to an equilibrium state in such systems and this property recently has been shown to be extraordinarily sensitive to the core block molecular weight in diblock copolymers. The dependence of micelle chain exchange dynamics on molecular architecture has not been reported. The present work conclusively addresses this issue using time-resolved small-angle neutron scattering (TR-SANS) applied to complimentary S-EP-S and EP-S-EP triblock copolymers dissolved in squalane, a selective solvent for the EP blocks, where S and EP refer to poly(styrene) and poly(ethylenepropylene), respectively. Following the overall SANS intensity as a function of time from judiciously deuterium labelled polymer and solvent mixtures directly probes the rate of molecular exchange. Remarkably, the two triblocks display exchange rates that differ by approximately ten orders of magnitude, even though the solvophobic S blocks are of comparable size. This discovery is considered in the context of a model that successfully explains S-EP diblock exchange dynamics.

  2. 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...... for a variety of novel mesophases, including biocontinuous phases and networks of ordered cross-linking micelles. Research has focused on structural studies of block copolymer systems, using small-angle scattering of X-rays and neutrons....

  3. Application of thermodynamic models to study micellar properties of sodium perfluoroalkyl carboxylates in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Perez, Alfredo [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain)], E-mail: alf@usc.es; Ruso, Juan M. [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Romero, Maria J. [Department of Inorganic Chemistry, Faculty of Chemistry, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Blanco, Elena [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Prieto, Gerardo [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Sarmiento, Felix [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain)

    2005-06-27

    Sodium perfluoroalkyl carboxylates (CnFONa) with n = 6, 9, 10 have been studied by conductivity measurements at different temperatures. The Krafft point was determined for C9FONa and C10FONa at the highest concentration studied by measuring the temperature dependence of the specific conductivity. The critical micelle concentration (cmc) and the ionization degree of the micelle ({beta}) were estimated from conductivity vs. molality plots at different temperatures. Using these data and previous results on temperature dependence of cmc and {beta} of sodium perfluoroheptanoate and perfluorooctanoate, different models were applied to obtain the thermodynamic properties of micellization. The results are discussed in terms of alkyl chain length.

  4. The critical micelle concentration of tetraethylammonium perfluorooctylsulfonate in water.

    Science.gov (United States)

    López-Fontán, José L; González-Pérez, Alfredo; Costa, Julian; Ruso, Juan M; Prieto, Gerardo; Schulz, Pablo C; Sarmiento, Félix

    2006-02-15

    The aggregation characteristics of tetraethylammonium perfluorooctylsulfonate in water were studied by several techniques: conductivity, pH, ion-selective electrodes, and surface tension. It was concluded that the aggregation process is gradual and starts with the formation of oligomers such as ion pairs that grow to give spherical micelles, which become wormlike with increasing concentration. Because of the size and hydrophobicity of the counterion, micelles quickly increase in ionization degree up to about 0.5. Differences among different critical micelle concentration values in the literature are explained on the basis of the gradual formation of micelles.

  5. Preparation of Nd2O3 nanorods in SDBS micelle system

    Institute of Scientific and Technical Information of China (English)

    吴萍萍; 张之魁; 宋根萍

    2014-01-01

    Well-crystallized Nd2O3 nanorods were prepared in the aqueous solution containing neodymium nitrate, sodium hydroxide (dissolved in ethanol) and sodium dodecyl benzene sulfonate (SDBS). One dimensional nanorods of neodymium hydroxide were synthesized first, which was then placed at different temperatures (600 and 800 °C) in a calcar for 10 h to form Nd2O3 nanorods. The morphology and crystal structure of the products were investigated by X-ray diffraction, transmission electron microscopy, field emission transmission electron microscopy, Fourier transform infrared spectroscopy and fluorescence spectrometry. By using SDBS micelles as a template, this method manufactured uniform morphology of hexagonal one-dimensional neodymium oxide nanorods with a diameter ranging from 20 to 70 nm. The length of the nanorods increased with prolonged reaction time.

  6. Sodium and Food Sources

    Science.gov (United States)

    ... Sources Top 10 Sources of Sodium How to Reduce Sodium Sodium Reduction Resources for Everyone Sodium Reduction Fact ... in processed food [PDF-867K] and how to reduce sodium. Sodium Reduction Is Challenging Types of food matter: ...

  7. Sodium in diet

    Science.gov (United States)

    Diet - sodium (salt); Hyponatremia - sodium in diet; Hypernatremia - sodium in diet; Heart failure - sodium in diet ... The body uses sodium to control blood pressure and blood volume. Your body also needs sodium for your muscles and nerves to work ...

  8. Hidden Sodium

    Centers for Disease Control (CDC) Podcasts

    2013-03-04

    In this podcast, learn about reducing sodium intake by knowing what to eat and the main sources of sodium in the diet. It's important for a healthy lifestyle.  Created: 3/4/2013 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 3/4/2013.

  9. Dietary sodium

    DEFF Research Database (Denmark)

    Graudal, Niels

    2015-01-01

    The 2013 Institute of Medicine (IOM) report "Sodium Intake in Populations: Assessment of Evidence" did not support the current recommendations of the IOM and the American Heart Association (AHA) to reduce daily dietary sodium intake to below 2,300 mg. The report concluded that the population...... Control (CDC), other public health advisory bodies, and major medical journals have continued to support the current policy of reducing dietary sodium.......-based health outcome evidence was not sufficient to define a safe upper intake level for sodium. Recent studies have extended this conclusion to show that a sodium intake below 2,300 mg/day is associated with increased mortality. In spite of this increasing body of evidence, the AHA, Centers for Disease...

  10. 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

  11. DEFORMATION OF COPOLYMER MICELLES INDUCED BY AMPHIPHILIC DIMER PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Xiao-chun Qin; Chun-lai Ren

    2012-01-01

    Combining self-consistent-field theory and density-functional theory,we systematically study the deformation of copolymer micelles induced by the presence of amphiphilic dimer particles.Due to the amphiphilic nature,dimer particles tend to accumulate onto the interface of the copolymer micelle.With increasing concentration of the symmetric dimer particles,which are made of two identical spherical particles,the micelle deforms from the initial sphere to ellipse,dumbbell,and finally separates into two micelles.Furthermore,asymmetric dimer particles,composed by two particles with different sizes,are considered to investigate the influence of geometry of dimer particles on the deformation of the micelle.It is found that the micelle inclines to deform into dumbbell due to the additional curvature originating in the gathering of asymmetric dimer particles onto the interface of the micelle.The present study on the deformation of micelles is useful to understand the possible shape variation in the course of cell division/fusion.

  12. Absorption Complex between Porphyrin and Phenothiazine in Reverse Micelles

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The interaction between amphiphilic porphyrin and phenothiazine in AOT/isooctane/ water reverse micelle was investigated by UV-Vis spectra. A new absorption complex between the two species is formed in such circumstances, which is ascribed to the enrichment of the components by the reverse micelle. The fluorescence quenching of CHTTP by PTH becomes more efficient after the formation of the absorption complex.

  13. Anthracene functionalized thermosensitive and UV-crosslinkable polymeric micelles

    NARCIS (Netherlands)

    Shi, Yang; Cardoso, Renata M.; Van Nostrum, Cornelus F.; Hennink, Wim E.

    2015-01-01

    An anthracene-functionalized thermosensitive block copolymer was synthesized, which formed micelles by heating its aqueous solution above the lower critical solution temperature (LCST). The micelles were subsequently crosslinked by UV illumination at 365 nm with a normal handheld UV lamp. The micell

  14. 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)

  15. 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

  16. Structure and stability of complex coacervate core micelles with lysozyme

    NARCIS (Netherlands)

    Lindhoud, S.; Vries, de R.J.; Norde, W.; Cohen Stuart, M.A.

    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 th

  17. Characterization of phospholipid mixed micelles by translational diffusion.

    Science.gov (United States)

    Chou, James J; Baber, James L; Bax, Ad

    2004-07-01

    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 Phi (Phi\\\\ le 15% v/v) of the micelles, experimental measurement of the concentration dependence, combined with use of the D (s)= D (o)(1-3.2lambdaPhi) 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.

  18. Characterization of Phospholipid Mixed Micelles by Translational Diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Chou, James J. [Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology (United States); Baber, James L.; Bax, Ad [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States)], E-mail: bax@nih.gov

    2004-07-15

    The concentration dependence of the translational self diffusion rate, D{sub 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 {phi} ({phi} {<=} 15% v/v) of the micelles, experimental measurement of the concentration dependence, combined with use of the D{sub s}=D{sub o}(1-3.2{lambda}{phi}) relationship, yields the hydrodynamic volume. For proteins, the hydrodynamic volume, derived from D{sub 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 {sup 15}N relaxation data.

  19. Chirality-mediated polypeptide micelles for regulated drug delivery.

    Science.gov (United States)

    Ding, Jianxun; Li, Chen; Zhang, Ying; Xu, Weiguo; Wang, Jincheng; Chen, Xuesi

    2015-01-01

    Two kinds of triblock poly(ethylene glycol)-polyleucine (PEG-PLeu) copolymers were synthesized through the ring-opening polymerization of L-Leu N-carboxyanhydride (NCA), or equivalent D-Leu NCA and L-Leu NCA with amino-terminated PEG as a macroinitiator. The amphiphilic copolymers spontaneously self-assembled into spherical micellar aggregations in an aqueous environment. The micelle with a racemic polypeptide core exhibited smaller critical micelle concentration and diameter compared to those with a levorotatory polypeptide core. A model anthracycline antineoplastic agent, i.e., doxorubicin (DOX), was loaded into micelles through nanoprecipitation, and the PEG-P(D,L-Leu) micelle exhibited higher drug-loading efficacy than that with a P(L-Leu) core-this difference was attributed to the flexible and compact P(L-Leu) core. Sustained in vitro DOX release from micelles with both levorotatory and racemic polypeptide cores was observed, and the DOX-loaded PEG-P(D,L-Leu) micelle exhibited a slower release rate. More interestingly, DOX-loaded micelles exhibited chirality-mediated antitumor efficacy in vitro and in vivo, which are all better than that of free DOX. Furthermore, both enhanced tumor inhibition and excellent security in vivo were confirmed by histopathological or in situ cell apoptosis analyses. Therefore, DOX-loaded PEG-PLeu micelles appear to be an interesting nanoscale polymeric formulation for promising malignancy chemotherapy.

  20. Designing Dendrimers to Offer Micelle-Type Nanocontainers

    Science.gov (United States)

    King, Angela G.

    2005-01-01

    The properties of a dendrimer with hydrophobic and hydrophilic substituents on an orthogonal plane is synthesized and studied. The resulting polymer contains one of the substituents in its concave interior and the other at the convex surface and the design promotes micelle-like behavior in polar solvent and inverted micelle arrangement in…

  1. Lactoferrin binding to transglutaminase cross-linked casein micelles

    NARCIS (Netherlands)

    Anema, S.G.; de Kruif, C.G.

    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

  2. Structure and Stability of Complex Coacervate Core Micelles with Lysozyme

    NARCIS (Netherlands)

    Lindhoud, Saskia; Vries, de Renko; Norde, Willem; Cohen Stuart, Martien A.

    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 th

  3. Structure and stability of complex coacervate core micelles with lysozyme

    NARCIS (Netherlands)

    Lindhoud, Saskia; de Vries, Renko; Norde, Willem; Cohen Stuart, Martien A.

    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 PAA(42)PAAm(417) an

  4. Photoinduced charge separation and enzyme reactions in reversed micelles.

    NARCIS (Netherlands)

    Verhaert, R.M.D.

    1989-01-01

    In this thesis the performance and coupling of two types of reaction, photoinduced charge separation and enzymatic conversion were studied in reversed micelles. Reversed micelles are 1 to 10 nm sized water droplets dispersed in an organic solution. The dispersant is a detergent (cationogenic, nonion

  5. Magainin II modified polydiacetylene micelles for cancer therapy

    Science.gov (United States)

    Yang, Danling; Zou, Rongfeng; Zhu, Yu; Liu, Ben; Yao, Defan; Jiang, Juanjuan; Wu, Junchen; Tian, He

    2014-11-01

    Polydiacetylene (PDA) micelles have been widely used to deliver anticancer drugs in the treatment of a variety of tumours and for imaging living cells. In this study, we developed an effective strategy to directly conjugate magainin II (MGN-II) to the surface of PDA micelles using a fluorescent dye. These stable and well-defined PDA micelles had high cytotoxicity in cancer cell lines, and were able to reduce the tumour size in mice. The modified PDA micelles improved the anticancer effects of MGN-II in the A549 cell line only at a concentration of 16.0 μg mL-1 (IC50). In addition, following irradiation with UV light at 254 nm, the PDA micelles gave rise to an energy transfer from the fluorescent dye to the backbone of PDA micelles to enhance the imaging of living cells. Our results demonstrate that modified PDA micelles can not only be used in the treatment of tumors in vitro and in vivo in a simple and directed way, but also offer a new platform for designing functional liposomes to act as anticancer agents.Polydiacetylene (PDA) micelles have been widely used to deliver anticancer drugs in the treatment of a variety of tumours and for imaging living cells. In this study, we developed an effective strategy to directly conjugate magainin II (MGN-II) to the surface of PDA micelles using a fluorescent dye. These stable and well-defined PDA micelles had high cytotoxicity in cancer cell lines, and were able to reduce the tumour size in mice. The modified PDA micelles improved the anticancer effects of MGN-II in the A549 cell line only at a concentration of 16.0 μg mL-1 (IC50). In addition, following irradiation with UV light at 254 nm, the PDA micelles gave rise to an energy transfer from the fluorescent dye to the backbone of PDA micelles to enhance the imaging of living cells. Our results demonstrate that modified PDA micelles can not only be used in the treatment of tumors in vitro and in vivo in a simple and directed way, but also offer a new platform for

  6. Polymer Micelles Laden Hydrogel Contact Lenses for Ophthalmic Drug Delivery.

    Science.gov (United States)

    Hu, Xiaohong; Tan, Huaping; Chen, Pin; Wang, Xin; Pang, Juan

    2016-06-01

    Hydrogel contact lens is an attractive drug carrier for the delivery of ophthalmic drugs. But limited drug loading capacity and burst release restricted its application in this field. Polymer micelle laden hydrogel contact lenses were designed for ophthalmic drug delivery in the work. β-CD/PAA/PEG ternary system was chosen to form polymer micelle. The micelle size could be adjusted by β-CD content and PAA/PEG concentration. The zeta potential of micelle was irrelevant to β-CD content, but influenced by PAA/PEG concentration. The absorbed drug concentration in micelle solution depended on both β-CD content and PAA/PEG concentration. Polymer micelle laden hydrogels were obtained by radical polymerization in situ. The transparency of polymer micelle laden hydrogel declined with PAA/PEG concentration increasing. The equilibrium water content and water loss showed that polymer micelle laden hydrogel with higher PAA/PEG concentration was in a higher swollen state. The dynamic viscoelastic properties howed that all polymer micelle laden hydrogels had some characteristics of crosslinked elastomers. The surface structure of freeze dried composite hydrogels was different from freeze dried pure hydrogel. The drug loading and releasing behaviors were detected to evaluate the drug loading and releasing capacity of hydrogels using orfloxacin and puerarin as model drugs. The results indicated the polymer micelle in hydrogel could hold or help to hold some ophthalmic drugs, and slow down orfloxacin release speed or keep puerarin stably stay for a time in hydrogels. In the end, it was found that the transparency of composite hydrogel became better after the hydrogel had been immersed in PBS for several weeks.

  7. Therapeutic surfactant-stripped frozen micelles

    Science.gov (United States)

    Zhang, Yumiao; Song, Wentao; Geng, Jumin; Chitgupi, Upendra; Unsal, Hande; Federizon, Jasmin; Rzayev, Javid; Sukumaran, Dinesh K.; Alexandridis, Paschalis; Lovell, Jonathan F.

    2016-05-01

    Injectable hydrophobic drugs are typically dissolved in surfactants and non-aqueous solvents which can induce negative side-effects. Alternatives like `top-down' fine milling of excipient-free injectable drug suspensions are not yet clinically viable and `bottom-up' self-assembled delivery systems usually substitute one solubilizing excipient for another, bringing new issues to consider. Here, we show that Pluronic (Poloxamer) block copolymers are amenable to low-temperature processing to strip away all free and loosely bound surfactant, leaving behind concentrated, kinetically frozen drug micelles containing minimal solubilizing excipient. This approach was validated for phylloquinone, cyclosporine, testosterone undecanoate, cabazitaxel and seven other bioactive molecules, achieving sizes between 45 and 160 nm and drug to solubilizer molar ratios 2-3 orders of magnitude higher than current formulations. Hypertonic saline or co-loaded cargo was found to prevent aggregation in some cases. Use of surfactant-stripped micelles avoided potential risks associated with other injectable formulations. Mechanistic insights are elucidated and therapeutic dose responses are demonstrated.

  8. Sodium - blood

    Science.gov (United States)

    ... gland problems such as Cushing syndrome or hyperaldosteronism Diabetes insipidus (type of diabetes in which kidneys are not able to conserve water) Too much salt or sodium bicarbonate in the diet Use of certain medicines, including corticosteroids, laxatives, lithium, ...

  9. Ultrasonic transformation of micelle structures: effect of frequency and power.

    Science.gov (United States)

    Yusof, Nor Saadah Mohd; Ashokkumar, Muthupandian

    2015-05-01

    A comprehensive investigation on the effect of ultrasonic frequency and power on the structural transformation of CTABr/NaSal micelles has been carried out. Sonication of this micelle system at various ultrasonic frequencies and power resulted in the formation and separation of two types of micelles. High viscoelastic threadlike micelles of ∼ 2 nm in diameter and several μm in length and tubular micelles possessing a viscosity slightly above that of water with ∼ 30-50 nm diameter and few hundred nm length. The structural transformation of micelles was induced by the shear forces generated during acoustic cavitation. At a fixed acoustic power of 40 W, the structural transformation was found to decrease from 211 to 647 kHz frequency due to the decreasing shear forces generated, as evidenced by rheological measurements and cryo-TEM images. At 355 kHz, an increase in the structural transformation was observed with an increase in acoustic power. These findings provide a knowledge base that could be useful for the manipulation of viscosity of micelles that may have applications in oil industry.

  10. 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.

  11. Encapsulation of Antifungals in Micelles Protects Candida albicans during Gall-Bladder Infection

    Science.gov (United States)

    Hsieh, Shih-Hung; Brunke, Sascha; Brock, Matthias

    2017-01-01

    Candida albicans is a dimorphic fungus that colonizes human mucosal surfaces with the potential to cause life-threatening invasive candidiasis. Studies on systemic candidiasis in a murine infection model using in vivo real-time bioluminescence imaging revealed persistence of C. albicans in the gall bladder under antifungal therapy. Preliminary analyses showed that bile conferred resistance against a wide variety of antifungals enabling survival in this cryptic host niche. Here, bile and its components were studied for their ability to reduce antifungal efficacy in order to elucidate the underlying mechanism of protection. While unconjugated bile salts were toxic to C. albicans, taurine, or glycine conjugated bile salts were well tolerated and protective against caspofungin and amphotericin B when exceeding their critical micellar concentration. Microarray experiments indicated that upregulation of genes generally known to mediate antifungal protection is not involved in the protection process. In contrast, rhodamine 6G and crystal violet in- and efflux experiments indicated encapsulation of antifungals in micelles, thereby reducing their bioavailability. Furthermore, farnesol sensing was abolished in the presence of conjugated bile salts trapping C. albicans cells in the hyphal morphology. This suggests that bioavailability of amphiphilic and hydrophobic compounds is reduced in the presence of bile. In contrast, small and hydrophilic molecules, such as cycloheximide, flucytosine, or sodium azide kept their antifungal properties. We therefore conclude that treatment of gall bladder and bile duct infections is hampered by the ability of bile salts to encapsulate antifungals in micelles. As a consequence, treatment of gall bladder or bile duct infections should favor the use of small hydrophilic drugs that are not solubilised in micelles. PMID:28203228

  12. 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.

  13. Pressure-induced structural transition of nonionic micelles

    Indian Academy of Sciences (India)

    V K Aswal; R Vavrin; J Kohlbrecher; A G Wagh

    2008-11-01

    We report dynamic light scattering and small angle neutron scattering studies of the pressure-induced structural transition of nonionic micelles of surfactant polyoxyethylene 10 lauryl ether (C12E10) in the pressure range 0 to 2000 bar. Measurements have been performed on 1 wt% C12E10 in aqueous solution with and without the addition of KF. Micelles undergo sphere to lamellar structural transitions as the pressure is increased. On addition of KF, rod-like micelles exist at ambient pressure, which results in rod-like to lamellar structural transition at a much lower pressure in the presence of KF. Micellar structural transitions have been observed to be reversible.

  14. Anion Exchange on Cationic Surfactant Micelles, and a Speciation Model for Estimating Anion Removal on Micelles during Ultrafiltration of Water.

    Science.gov (United States)

    Chen, Ming; Jafvert, Chad T

    2017-07-05

    Surfactant micelles combined with ultrafiltration can partially, or sometimes nearly completely, separate various ionic and nonionic pollutants from water. To this end, the selectivity of aqueous micelles composed of either cetyltrimethylammonium (CTA(+)) bromide or cetylpyridinium (CP(+)) chloride toward many environmentally relevant anions (IO3(-), F(-), Cl(-), HCO3(-), NO2(-), Br(-), NO3(-), H2PO4(-), HPO4(2-), SO4(2-), and CrO4(2-)) was investigated. Selectivity coefficients of CTA(+) micelles (with respect to Br(-)) and CP(+) micelle (with respect to Cl(-)) for these anions were evaluated using a simple thermodynamic ion exchange model. The sequence of anion affinity for the CTA(+) micelles and for the CP(+) micelles were the same, with decreasing affinity occurring in the order of: CrO4(2-) > SO4(2-) > HPO4(2-) > NO3(-) > Br(-) > NO2(-) > Cl(-) > HCO3(-) > H2PO4(-) ≈ F(-). From the associated component mass balance and ion exchange (i.e., mass action) equations, an overall speciation model was developed to predict the distribution of all anions between the aqueous and micellar pseudophase for complex ionic mixtures. Experimental results of both artificial and real surface waters were in good agreement to model predictions. Further, the results indicated that micelles combined with ultrafiltration may be a potential technology for nutrient and other pollutant removal from natural or effluent waters.

  15. 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

  16. Multicompartmental Microcapsules from Star Copolymer Micelles

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Ikjun; Malak, Sidney T.; Xu, Weinan; Heller, William T.; Tsitsilianis, Constantinos; Tsukruk, Vladimir V.

    2013-02-26

    We present the layer-by-layer (LbL) assembly of amphiphilic heteroarm pH-sensitive star-shaped polystyrene-poly(2-pyridine) (PSnP2VPn) block copolymers to fabricate porous and multicompartmental microcapsules. Pyridine-containing star molecules forming a hydrophobic core/hydrophilic corona unimolecular micelle in acidic solution (pH 3) were alternately deposited with oppositely charged linear sulfonated polystyrene (PSS), yielding microcapsules with LbL shells containing hydrophobic micelles. The surface morphology and internal nanopore structure of the hollow microcapsules were comparatively investigated for shells formed from star polymers with a different numbers of arms (9 versus 22) and varied shell thickness (5, 8, and 11 bilayers). The successful integration of star unimers into the LbL shells was demonstrated by probing their buildup, surface segregation behavior, and porosity. The larger arm star copolymer (22 arms) with stretched conformation showed a higher increment in shell thickness due to the effective ionic complexation whereas a compact, uniform grainy morphology was observed regardless of the number of deposition cycles and arm numbers. Small-angle neutron scattering (SANS) revealed that microcapsules with hydrophobic domains showed different fractal properties depending upon the number of bilayers with a surface fractal morphology observed for the thinnest shells and a mass fractal morphology for the completed shells formed with the larger number of bilayers. Moreover, SANS provides support for the presence of relatively large pores (about 25 nm across) for the thinnest shells as suggested from permeability experiments. The formation of robust microcapsules with nanoporous shells composed of a hydrophilic polyelectrolyte with a densely packed hydrophobic core based on star amphiphiles represents an intriguing and novel case of compartmentalized microcapsules with an ability to simultaneously store different hydrophilic, charged, and hydrophobic

  17. Mixed micelle cloud point-magnetic dispersive μ-solid phase extraction of doxazosin and alfuzosin.

    Science.gov (United States)

    Gao, Nannan; Wu, Hao; Chang, Yafen; Guo, Xiaozhen; Zhang, Lizhen; Du, Liming; Fu, Yunlong

    2015-01-01

    Mixed micelle cloud point extraction (MM-CPE) combined with magnetic dispersive μ-solid phase extraction (MD-μ-SPE) has been developed as a new approach for the extraction of doxazosin (DOX) and alfuzosin (ALF) prior to fluorescence analysis. The mixed micelle anionic surfactant sodium dodecyl sulfate and non-ionic polyoxyethylene(7.5)nonylphenylether was used as the extraction solvent in MM-CPE, and diatomite bonding Fe₃O₄ magnetic nanoparticles were used as the adsorbent in MD-μ-SPE. The method was based on MM-CPE of DOX and ALF in the surfactant-rich phase. Magnetic materials were used to retrieve the surfactant-rich phase, which easily separated from the aqueous phase under magnetic field. At optimum conditions, a linear relationship between DOX and ALF was obtained in the range of 5-300 ng mL(-1), and the limits of detection were 0.21 and 0.16 ng mL(-1), respectively. The proposed method was successfully applied for the determination of the drugs in pharmaceutical preparations, urine samples, and plasma samples.

  18. Mixed micelle cloud point-magnetic dispersive μ-solid phase extraction of doxazosin and alfuzosin

    Science.gov (United States)

    Gao, Nannan; Wu, Hao; Chang, Yafen; Guo, Xiaozhen; Zhang, Lizhen; Du, Liming; Fu, Yunlong

    2015-01-01

    Mixed micelle cloud point extraction (MM-CPE) combined with magnetic dispersive μ-solid phase extraction (MD-μ-SPE) has been developed as a new approach for the extraction of doxazosin (DOX) and alfuzosin (ALF) prior to fluorescence analysis. The mixed micelle anionic surfactant sodium dodecyl sulfate and non-ionic polyoxyethylene(7.5)nonylphenylether was used as the extraction solvent in MM-CPE, and diatomite bonding Fe3O4 magnetic nanoparticles were used as the adsorbent in MD-μ-SPE. The method was based on MM-CPE of DOX and ALF in the surfactant-rich phase. Magnetic materials were used to retrieve the surfactant-rich phase, which easily separated from the aqueous phase under magnetic field. At optimum conditions, a linear relationship between DOX and ALF was obtained in the range of 5-300 ng mL-1, and the limits of detection were 0.21 and 0.16 ng mL-1, respectively. The proposed method was successfully applied for the determination of the drugs in pharmaceutical preparations, urine samples, and plasma samples.

  19. Fluorophotometric determination of critical micelle concentration (CMC) of ionic and non-ionic surfactants with carbon dots via Stokes shift.

    Science.gov (United States)

    Lavkush Bhaisare, Mukesh; Pandey, Sunil; Shahnawaz Khan, M; Talib, Abou; Wu, Hui-Fen

    2015-01-01

    A new and facile method for the determination of critical micelle concentration (CMC) of ionic and non-ionic surfactants is proposed in this article. Carbon dots exhibited substantial fluorescence and therefore enhanced the sensitivity of this evaluation. Understanding the formation of surfactant micelles is vital for the applications of biomedicine such as drug fabrication and smart molecular vehicles in delivering therapeutic dosage to various molecular sites. The fluorescence property of carbon dots was utilized for the first time to estimate the critical micelle concentration of surfactants. The central concept of the approach is based on the Stokes shift determination of a system composed of constant amount of carbon dots with varying concentrations of ionic and non-ionic surfactants. The synthesized carbon dots were characterized by FTIR, TEM, XRD, Raman, UV, and fluorescence spectroscope. The carbon dots were excited at 280 nm so as to obtain maximum emission for the Stokes shift measurement. The CMC value of cetyltrimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), Triton X-100, dodecyldimethyl(3-sulfopropyl)ammonium hydroxide (SB-12) evaluated by this approach was found to be 0.98, 7.3, 0.19, and 3.5mM, respectively. The signals of spectra were assigned and explained in terms of both electron transitions between specific molecular orbital and the interaction with solvent.

  20. Encapsulation into complex coacervate core micelles promotes EGFP dimerization

    NARCIS (Netherlands)

    Nolles, A.; Dongen, Van N.J.E.; Westphal, A.H.; Visser, A.J.W.G.; Kleijn, J.M.; Berkel, Van W.J.H.; Borst, J.W.

    2017-01-01

    Complex coacervate core micelles (C3Ms) are colloidal structures useful for encapsulation of biomacromolecules. We previously demonstrated that enhanced green fluorescent protein (EGFP) can be encapsulated into C3Ms using the diblock copolymer

  1. Enantiomer separation by ultrafiltration of enantioselective micelles in multistage systems

    NARCIS (Netherlands)

    Overdevest, P.E.M.

    2000-01-01

    The Food and Bioprocess Engineering Group of Wageningen University, The Netherlands, is developing a new enantiomer separation system that is based on ultrafiltration (UF) of enantioselective micelles containing chiral selector molecules. Enantiomer molecules are optical isomers (mirror images), and

  2. 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

  3. Effects of copolymer component on the properties of phosphorylcholine micelles

    Directory of Open Access Journals (Sweden)

    Wu Z

    2017-01-01

    Full Text Available Zhengzhong Wu,1 Mengtan Cai,1 Jun Cao,2 Jiaxing Zhang,1 Xianglin Luo1,3 1College of Polymer Science and Engineering, 2National Engineering Research Center for Biomaterials, 3State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, People’s Republic of China Abstract: Zwitterionic polymers have unique features, such as good compatibility, and show promise in the application of drug delivery. In this study, the zwitterionic copolymers, poly(ε-caprolactone-b-poly(2-methacryloyloxyethyl phosphorylcholine with disulfide (PCL-ss-PMPC or poly(ε-caprolactone-b-poly(2-methacryloyloxyethyl phosphorylcholine or without disulfide (PCL-PMPC and with different block lengths in PCL-ss-PMPC, were designed. The designed copolymers were obtained by a combination of ring-opening polymerization and atom transferring radical polymerization. The crystallization properties of these polymers were investigated. The micelles were prepared based on the obtained copolymers with zwitterionic phosphorylcholine as the hydrophilic shell and PCL as the hydrophobic core. The size distributions of the blank micelles and the doxorubicin (DOX-loaded micelles were uniform, and the micelle diameters were <100 nm. In vitro drug release and intracellular drug release results showed that DOX-loaded PCL-ss-PMPC micelles could release drugs faster responding to the reduction condition and the intracellular microenvironment in contrast to PCL-PMPC micelles. Moreover, in vitro cytotoxicity evaluation revealed that the designed copolymers possessed low cell toxicity, and the inhibiting effect of DOX-loaded phosphorylcholine micelles to tumor cells was related to the components of these copolymers. These results reveal that the reduction-responsive phosphorylcholine micelles with a suitable ratio of hydrophilic/hydrophobic units can serve as promising drug carriers. Keywords: zwitterionic, reduction-sensitive, disulfide, phosphorylcholine

  4. Atomic Model and Micelle Dynamics of QS-21 Saponin

    Directory of Open Access Journals (Sweden)

    Conrado Pedebos

    2014-03-01

    Full Text Available QS-21 is a saponin extracted from Quillaja saponaria, widely investigated as a vaccine immunoadjuvant. However, QS-21 use is mainly limited by its chemical instability, significant variety in molecular composition and low tolerance dose in mammals. Also, this compound tends to form micelles in a concentration-dependent manner. Here, we aimed to characterize its conformation and the process of micelle formation, both experimentally and computationally. Therefore, molecular dynamics (MD simulations were performed in systems containing different numbers of QS-21 molecules in aqueous solution, in order to evaluate the spontaneous micelle formation. The applied methodology allowed the generation of micelles whose sizes were shown to be in high agreement with small-angle X-ray scattering (SAXS. Furthermore, the ester linkage between fucose and acyl chain was less solvated in the micellar form, suggesting a reduction in hydrolysis. This is the first atomistic interpretation of previous experimental data, the first micellar characterization of saponin micelles by SAXS and first tridimensional model of a micelle constituted of saponins, contributing to the understanding of the molecular basis of these compounds.

  5. Structure and stability of complex coacervate core micelles with lysozyme.

    Science.gov (United States)

    Lindhoud, Saskia; Vries, Renko de; Norde, Willem; Stuart, Martien A Cohen

    2007-07-01

    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 the positively charged homopolymer PDMAEMA150. For encapsulation, part of the positively charged homopolymer was replaced by the positively charged globular protein lysozyme. We have studied the formation, structure, and stability of the resulting micelles for three different mixing ratios of homopolymer and lysozyme: a system predominantly consisting of homopolymer, a system predominantly consisting of lysozyme, and a system where the molar ratio between the two positively charged molecules was almost one. We also studied complexes made of only lysozyme and PAA42PAAm417. Complex formation and the salt-induced disintegration of the complexes were studied using dynamic light-scattering titrations. Small-angle neutron scattering was used to investigate the structures of the cores. We found that micelles predominantly consisting of homopolymer are spherical but that complex coacervate core micelles predominantly consisting of lysozyme are nonspherical. The stability of the micelles containing a larger fraction of lysozyme is lower.

  6. [Strengthening Effects of Sodium Salts on Washing Kerosene Contaminated Soil with Surfactants].

    Science.gov (United States)

    Huang, Zhao-lu; Chen, Quan-yuan; Zhou, Juan; Xie, Mo-han

    2015-05-01

    The impact of sodium salt on kerosene contaminated soil washing with surfactants was investigated. The results indicated that sodium silicate greatly enhanced the washing efficiency of SDS. Sodium tartrate can largely enhance the washing efficiency of SDBS and Brij35. Sodium salts can enhance the washing efficiency on kerosene contaminated with TX-100. No significant differences were observed between different sodium salts. Sodium salt of humic acid and sodium silicate had similar enhancement on kerosene contaminated soil washing with saponin. Sodium humate can be a better choice since its application can also improve soil quality. The enhancement of sodium silicate on kerosene contaminated soil washing with Tw-80 increased with the increase of Tw-80 dosage. However, the impact of sodium chloride and sodium tartrate was opposite to sodium silicate. Sodium salts can reduce surface tension and critical micelle concentration of ionic surfactants to enhance the washing. Sodium salts can also reduce re-adsorption of oil to soil with nonionic surfactants to enhance the washing. Kerosene contamination can increase the contact angle of soil, which indicated the increase of hydrophilicity of soil. Washing with surfactants can reduce the hydrophilicitiy of soil according to contact angle measurement, which indicated that kerosene contaminated soil remediation with surfactant can also benefit nutrient and water transportation in the contaminated soil.

  7. Adsorption characteristics of zinc ions on sodium dodecyl sulfate in process of micellar-enhanced ultrafiltration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    To separate zinc ions from aqueous solution efficiently, micellar-enhanced ultrafiltration(MEUF) of hollow ultrafiltration membrane was used with sodium dodecyl sulfate(SDS) as surfactant. The formation of micellar and the adsorption mechanism were investigated, including the influence of the ratio of SDS to zinc ions on the micelle quantity, the micelle ratio, the gross adsorptive capacity, the rejection of zinc ions and the adsorption isotherm law. The results show that the rejection rate of zinc ions reaches 97% and the adsorption of zinc ions on SDS conforms to the Langmuir adsorption isotherm and the adsorption is a chemical adsorption process.

  8. Test Your Sodium Smarts

    Science.gov (United States)

    ... You may be surprised to learn how much sodium is in many foods. Sodium, including sodium chloride ... foods with little or no salt. Test your sodium smarts by answering these 10 questions about which ...

  9. Micelles and reverse micelles in the nickel bis(2-ethylhexyl) sulfosuccinate/water/isooctane microemulsion.

    Science.gov (United States)

    Garza, Cristina; Carbajal-Tinoco, Mauricio D; Castillo, Rolando

    2004-12-01

    The ternary system Ni(2+)(AOT)(2) (nickel 2-bis[2-ethylhexyl] sulfosuccinate)/water/isooctane presents w/o and o/w microemulsions with a Winsor progression (2Phi-3Phi-2Phi), without the addition of salt; the "fish diagram" was obtained for alpha=0.5 and gamma=0.02-0.22. Using static and dynamic light scattering the micellar size, the ratio of water to surfactant, and the density of micelles for this system were estimated. In addition, the mean interfacial curvature as a function of temperature was obtained.

  10. 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...

  11. Low sodium diet (image)

    Science.gov (United States)

    ... for you. Look for these words on labels: low-sodium, sodium-free, no salt added, sodium-reduced, or ... for you. Look for these words on labels: low-sodium, sodium-free, no salt added, sodium-reduced, or ...

  12. 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.

  13. Applications of polymeric micelles with tumor targeted in chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Ding Hui; Wang Xiaojun; Zhang Song; Liu Xinli, E-mail: Vip.lxl@163.com [Shandong Polytechnic University, Shandong Provincial Key Laboratory of Microbial Engineering (China)

    2012-11-15

    Polymeric micelles (PMs) have gained more progress as a carrier system with the quick development of biological and nanoparticle techniques. In particular, PMs with smart targeting can deliver anti-cancer drugs directly into tumor cells at a sustained rate. PMs with core-shell structure (with diameters of 10 {approx} 100 nm) have been prepared by a variety of biodegradable and biocompatible polymers via a self-assembly process. The preparation of polymeric micelles with stimuli-responsive block copolymers or modification of target molecules on polymeric micelles' surface are able to significantly improve the efficiency of drug delivery. Polymeric micelles, which have been considered as a novel promising drug carrier for cancer therapeutics, are rapidly evolving and being introduced in an attempt to overcome several limitations of traditional chemotherapeutics, including water solubility, tumor-specific accumulation, anti-tumor efficacy, and non-specific toxicity. This review describes the preparation of polymeric micelles and the targeted modification which greatly enhance the effects of chemotherapeutic agents.

  14. Stability of complex coacervate core micelles containing metal coordination polymer.

    Science.gov (United States)

    Yan, Yun; de Keizer, Arie; Cohen Stuart, Martien A; Drechsler, Markus; Besseling, Nicolaas A M

    2008-09-01

    We report on the stability of complex coacervate core micelles, i.e., C3Ms (or PIC, BIC micelles), containing metal coordination polymers. In aqueous solutions these micelles are formed between charged-neutral diblock copolymers and oppositely charged coordination polymers formed from metal ions and bisligand molecules. The influence of added salt, polymer concentration, and charge composition was investigated by using light scattering and cryo-TEM techniques. The scattering intensity decreases strongly with increasing salt concentration until a critical salt concentration beyond which no micelles exist. The critical micelle concentration increases almost exponentially with the salt concentration. From the scattering results it follows that the aggregation number decreases with the square root of the salt concentration, but the hydrodynamic radius remains constant or increases slightly. It was concluded that the density of the core decreases with increasing ionic strength. This is in agreement with theoretical predictions and is also confirmed by cryo-TEM measurements. A complete composition diagram was constructed based on the composition boundaries obtained from light scattering titrations.

  15. A novel temperature-responsive micelle for enhancing combination therapy

    Directory of Open Access Journals (Sweden)

    Peng CL

    2016-07-01

    Full Text Available Cheng-Liang Peng,1,* Yuan-I Chen,2,3,* Hung-Jen Liu,2 Pei-Chi Lee,2 Tsai-Yueh Luo,1 Ming-Jium Shieh2,3 1Isotope Application Division, Institute of Nuclear Energy Research, Taoyuan, 2Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, 3Department of Oncology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan *These authors contributed equally to this work Abstract: A novel thermosensitive polymer p(N-isopropylacrylamide-co-poly[ethylene glycol] methyl ether acrylate-block-poly(epsilon-caprolactone, p(NIPAAM-co-PEGMEA-b-PCL, was synthesized and developed as nanomicelles. The hydrophobic heat shock protein 90 inhibitor 17-allylamino-17-demethoxygeldanamycin and the photosensitizer cyanine dye infrared-780 were loaded into the core of the micelles to achieve both chemotherapy and photothermal therapy simultaneously at the tumor site. The release of the drug could be controlled by varying the temperature due to the thermosensitive nature of the micelles. The micelles were less than 200 nm in size, and the drug encapsulation efficiency was >50%. The critical micelle concentrations were small enough to allow micelle stability upon dilution. Data from cell viability and animal experiments indicate that this combination treatment using photothermal therapy with chemotherapy had synergistic effects while decreasing side effects. Keywords: thermosensitive, photothermal therapy, chemotherapy, nanocarrier, control release, synergistic effect

  16. 硫酸溶液中胶束催化Ce(IV)氧化D-甘露糖%Micelle Catalyzed Oxidation of D-Mannose by Cerium (Ⅳ) in Sulfuric Acid

    Institute of Scientific and Technical Information of China (English)

    KABIR-UD-DIN; ALI Mohd. Sajid; KHAN Zaheer

    2008-01-01

    Kinetics of D-mannose oxidation by cerium (IV) was studied in a sulfuric acid medium at 40℃ both in absence and presence of ionic micelles. In both cases, the rate of the reaction was first-order in D-mannose and in cerium(Ⅳ), which decreased with increasing [H2SO4]. This suggested that the redox reaction followed the same mechanism. The reaction proceeded through formation of an intermediate complex, which was proved by kinetic method. The complex underwent slow unimolecular decomposition to a free radical that reacted with cerium (Ⅳ) to afford the product. The catalytic role of cationic cetyltrimethylammonium bromide (CTAB) micelles was best explained by the Menger-Portnoy model. The study of the effect of CTAB also indicated that a negatively charged species was reactive form of cerium (Ⅳ). From the kinetic data, micelle-cerium (Ⅳ) binding and rate constants in micellar medium were evaluated.The anionic micelle of sodium dodecyl sulfate plays no catalytic role. The oxidation has the rate expression: --d[Ce(Ⅳ)]= k1Kcl[D-mannose] [Ce(Ⅳ)]dt Different activation parameters for micelle catalyzed and uncatalyzed paths were also calculated and discussed.

  17. 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

  18. Mixed micelles of 7,12-dioxolithocholic acid and selected hydrophobic bile acids: interaction parameter, partition coefficient of nitrazepam and mixed micelles haemolytic potential.

    Science.gov (United States)

    Poša, Mihalj; Tepavčević, Vesna

    2011-09-01

    The formation of mixed micelles built of 7,12-dioxolithocholic and the following hydrophobic bile acids was examined by conductometric method: cholic (C), deoxycholic (D), chenodeoxycholic (CD), 12-oxolithocholic (12-oxoL), 7-oxolithocholic (7-oxoL), ursodeoxycholic (UD) and hiodeoxycholic (HD). Interaction parameter (β) in the studied binary mixed micelles had negative value, suggesting synergism between micelle building units. Based on β value, the hydrophobic bile acids formed two groups: group I (C, D and CD) and group II (12-oxoL, 7-oxoL, UD and HD). Bile acids from group II had more negative β values than bile acids from group I. Also, bile acids from group II formed intermolecular hydrogen bonds in aggregates with both smaller (2) and higher (4) aggregation numbers, according to the analysis of their stereochemical (conformational) structures and possible structures of mixed micelles built of these bile acids and 7,12-dioxolithocholic acid. Haemolytic potential and partition coefficient of nitrazepam were higher in mixed micelles built of the more hydrophobic bile acids (C, D, CD) and 7,12-dioxolithocholic acid than in micelles built only of 7,12-dioxolithocholic acid. On the other hand, these mixed micelles still had lower values of haemolytic potential than micelles built of C, D or CD. The mixed micelles that included bile acids: 12-oxoL, 7-oxoL, UD or HD did not significantly differ from the micelles of 7,12-dioxolithocholic acid, observing the values of their haemolytic potential.

  19. 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.

  20. Multicompartment Micelles From π-Shaped ABC Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    XIA Jun; ZHONG Chong-Li

    2007-01-01

    Dissipative particle dynamics simulations were performed on the morphology and structure of multicompartment micelles formed from n-shaped ABC block copolymers in water. The influences of chain architectures were studied in a systematic way, and a rich variety of morphologies were observed, such as spherical, wormlike,X-shaped, Y-shaped, ribbon-like, layered rod-like, layered disk-like, as well as network morphologies. The simulations show that the distance between the two grafts plays an important role in control of the morphology. Since π-shaped ABC block copolymers can be reduced to linear ABC and star ABC block copolymers, they are good model copolymers for studying the self-assembly of complex block copolymers into micelles. The knowledge obtained in this work as well as the new morphologies identified provide useful information for future rational design and synthesis of novel multicompartment micelles.

  1. 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.

  2. From micelle supramolecular assemblies in selective solvents to isoporous membranes.

    Science.gov (United States)

    Nunes, Suzana P; Karunakaran, Madhavan; Pradeep, Neelakanda; Behzad, Ali Reza; Hooghan, Bobby; Sougrat, Rachid; He, Haoze; Peinemann, Klaus-Viktor

    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.

  3. 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.

  4. Casein micelles: size distribution in milks from individual cows.

    Science.gov (United States)

    de Kruif, C G Kees; Huppertz, Thom

    2012-05-09

    The size distribution and protein composition of casein micelles in the milk of Holstein-Friesian cows was determined as a function of stage and number of lactations. Protein composition did not vary significantly between the milks of different cows or as a function of lactation stage. Differences in the size and polydispersity of the casein micelles were observed between the milks of different cows, but not as a function of stage of milking or stage of lactation and not even over successive lactations periods. Modal radii varied from 55 to 70 nm, whereas hydrodynamic radii at a scattering angle of 73° (Q² = 350 μm⁻²) varied from 77 to 115 nm and polydispersity varied from 0.27 to 0.41, in a log-normal distribution. Casein micelle size in the milks of individual cows was not correlated with age, milk production, or lactation stage of the cows or fat or protein content of the milk.

  5. Anomalous diffusion and stress relaxation in surfactant micelles

    Science.gov (United States)

    Dhakal, Subas; Sureshkumar, Radhakrishna

    2017-07-01

    We investigate the mechanisms of anomalous diffusion in cationic surfactant micelles using molecular dynamics simulations in the presence of explicit salt and solvent-mediated interactions. Simulations show that when the counterion density increases, saddle-shaped branched interfaces manifest. In experiments, branched structures exhibit lower viscosity as compared to linear and wormlike micelles. This has long been attributed to stress relaxation arising from the sliding motion of branches along the main chain. Our simulations reveal a mechanism of branch motion resulting from an enhanced counterion condensation at the branched interfaces and provide quantitative evidence of stress relaxation facilitated by branched sliding. Furthermore, depending on the surfactant and salt concentrations, which in turn determine the microstructure, we observe normal, subdiffusive, and superdiffusive motions of surfactants. Specifically, superdiffusive behavior is associated with branch sliding, breakage and recombination of micelle fragments, as well as constraint release in entangled systems.

  6. COMPARISON OF DRUG DELIVERY PROPERTIES OF PEG-b-PDHPC MICELLES WITH DIFFERENT COMPOSITIONS

    Institute of Scientific and Technical Information of China (English)

    Chun-yan Long; Ming-ming Sheng; Bin He; Yao Wu; Gang Wang; Zhong-wei Gu

    2012-01-01

    An anti-tumor drug doxombicin was encapsulated in micelles of poly(ethylene glycol)-b-poly(2,2-dihydroxyl-methyl propylene carbonate) (PEG-b-PDHPC) diblock copolymers.The morphology of both blank micelles and drug loaded micelles was characterized by TEM.The in vitro drug release profiles of micelles were investigated.The cytotoxicity of the micelles was evaluated by incubating with Hela tumor cells and 3T3 fibroblasts.The drug loaded micelles were co-cultured with HepG2 cells to evaluate the in vitro anti-tumor efficacies.The results showed that the mean sizes of both micelles with different copolymer compositions increased after being loaded with drugs.The drug release rate of PEG45-b-PDHPC34 micelles was faster than that of rnPEG114-b-PDHPC26 micelles.Both of the two block copolymers were non-toxic.The confocal laser scanning microscopy and flow cytometry results showed that both the drug loaded micelles could be internalized efficiently in HepG2 cells.The PEG45-b-PDHPC34 micelles exhibited higher anti-tumor activity comparing to mPEG114-b-PDHPC26 micelles.

  7. Controlled mixing of lanthanide(III) ions in coacervate core micelles.

    Science.gov (United States)

    Wang, Junyou; Velders, Aldrik H; Gianolio, Eliana; Aime, Silvio; Vergeldt, Frank J; Van As, Henk; Yan, Yun; Drechsler, Markus; de Keizer, Arie; Cohen Stuart, Martien A; van der Gucht, Jasper

    2013-05-01

    This article presents a facile strategy to combine Eu(3+) and Gd(3+) ions into coacervate core micelles in a controlled way with a statistical distribution of the ions. Consequently, the formed micelles show a high tunability between luminescence and relaxivity. These highly stable micelles present great potential for new materials, e.g. as bimodal imaging probes.

  8. Shell and core cross-linked poly(L-lysine)/poly(acrylic acid) complex micelles.

    Science.gov (United States)

    Hsieh, Yi-Hsuan; Hsiao, Yung-Tse; Jan, Jeng-Shiung

    2014-12-21

    We report the versatility of polyion complex (PIC) micelles for the preparation of shell and core cross-linked (SCL and CCL) micelles with their surface properties determined by the constituent polymer composition and cross-linking agent. The negatively and positively charged PIC micelles with their molecular structure and properties depending on the mixing weight percentage and polymer molecular weight were first prepared by mixing the negatively and positively charged polyions, poly(acrylic acid) (PAA) and poly(L-lysine) (PLL). The feasibility of preparing SCL micelles was demonstrated by cross-linking the shell of the negatively and positively charged micelles using cystamine and genipin, respectively. The core of the micelles can be cross-linked by silica deposition to stabilize the assemblies. The shell and/or core cross-linked micelles exhibited excellent colloid stability upon changing solution pH. The drug release from the drug-loaded SCL micelles revealed that the controllable permeability of the SCL micelles can be achieved by tuning the cross-linking degree and the SCL micelles exhibited noticeable pH-responsive behavior with accelerated release under acidic conditions. With the versatility of cross-linking strategies, it is possible to prepare a variety of SCL and CCL micelles from PIC micelles.

  9. Improvement in enzyme activity and stability by addition of low molecular weight polyethylene glycol to sodium bis(2-ethyl-L-hexyl)sulfosuccinate/isooctane reverse micellar system.

    Science.gov (United States)

    Talukder, M M R; Takeyama, T; Hayashi, Y; Wu, J C; Kawanishi, T; Shimizu, N; Ogino, C

    2003-08-01

    The activity and stability of Chromobacterium viscosum lipase (glycerolester hydrolase, EC 3.1.1.3)-catalyzed olive oil hydrolysis in sodium bis (2-ethyl-l-hexyl)sulfosuccinate (AOT)/isooctane reverse micelles is increased appreciably when low molecular weight polyethylene glycol (PEG 400) is added to the reverse micelles. To understand the effect of PEG 400 on the phase behavior of the reverse micellar system, the phase diagram of AOT/ PEG 400/water/isooctane system was studied. The influences of relevant parameters on the catalytic activity in AOT/PEG 400 reverse micelles were investigated and compared with the results in the simple AOT reverse micelles. In the presence of PEG 400, the linear decreasing trend of the lipase activity with AOT concentration, which is observed in the simple AOT reverse micelles, disappeared. Enzyme entrapped in AOT/PEG reverse micelles was very stable, retaining >75% of its initial activity after 60 d, whereas the half-life in simple AOT reverse micelles was 38 d. The kinetics parameter maximum velocity (Vmax) exhibiting the temperature dependence and the activation energy obtained by Arrhenius plot was suppressed significantly by the addition of PEG 400.

  10. Interactions between selected bile salts and Triton X-100 or sodium lauryl ether sulfate

    Directory of Open Access Journals (Sweden)

    Ćirin Dejan M

    2011-12-01

    Full Text Available Abstract Background In order to develop colloidal drug carriers with desired properties, it is important to determine physico-chemical characteristics of these systems. Bile salt mixed micelles are extensively studied as novel drug delivery systems. The objective of the present investigation is to develop and characterize mixed micelles of nonionic (Triton X-100 or anionic (sodium lauryl ether sulfate surfactant having oxyethylene groups in the polar head and following bile salts: cholate, deoxycholate and 7-oxodeoxycholate. Results The micellization behaviour of binary anionic-nonionic and anionic-anionic surfactant mixtures was investigated by conductivity and surface tension measurements. The results of the study have been analyzed using Clint's, Rubingh's, and Motomura's theories for mixed binary systems. The negative values of the interaction parameter indicate synergism between micelle building units. It was noticed that Triton X-100 and sodium lauryl ether sulfate generate the weakest synergistic interactions with sodium deoxycholate, while 7-oxodeoxycholate creates the strongest attractive interaction with investigated co-surfactants. Conclusion It was concluded that increased synergistic interactions can be attributed to the larger number of hydrophilic groups at α side of the bile salts. Additionally, 7-oxo group of 7-oxodeoxycholate enhance attractive interactions with selected co-surfactants more than 7-hydroxyl group of sodium cholate.

  11. Bile salt/phospholipid mixed micelle precursor pellets prepared by fluid-bed coating

    Directory of Open Access Journals (Sweden)

    Dong F

    2013-04-01

    Full Text Available Fuxia Dong,1,2 Yunchang Xie,1 Jianping Qi,1 Fuqiang Hu,3 Yi Lu,1 Sanming Li,2 Wei Wu1 1School of Pharmacy, Fudan University, Key Laboratory of Smart Drug Delivery of Ministry of Education and PLA, Shanghai, People’s Republic of China; 2School of Pharmacy, Shenyang Pharmaceutical University, Liaoning, People’s Republic of China; 3School of Pharmacy, Zhejiang University, Hangzhou, People’s Republic of China Abstract: Bile salt/phospholipid mixed micelles (MMs are potent carriers used for oral absorption of drugs that are poorly soluble in water; however, there are many limitations associated with liquid formulations. In the current study, the feasibility of preparing bile salt/phospholipid MM precursor (preMM pellets with high oral bioavailability, using fluid-bed coating technology, was examined. In this study, fenofibrate (FB and sodium deoxycholate (SDC were used as the model drug and the bile salt, respectively. To prepare the MMs and to serve as the micellular carrier, a weight ratio of 4:6 was selected for the sodium deoxycholate/phospholipids based on the ternary phase diagram. Polyethylene glycol (PEG 6000 was selected as the dispersion matrix for precipitation of the MMs onto pellets, since it can enhance the solubilizing ability of the MMs. Coating of the MMs onto the pellets using the fluid-bed coating technology was efficient and the pellets were spherical and intact. MMs could be easily reconstituted from preMM pellets in water. Although they existed in a crystalline state in the preMM pellets, FB could be encapsulated into the reconstituted MMs, and the MMs were redispersed better than solid dispersion pellets (FB:PEG = 1:3 and Lipanthyl®. The redispersibility of the preMM pellets increased with the increase of the FB/PEG/micellar carrier. PreMM pellets with a FB:PEG:micellar carrier ratio of 1:1.5:1.5 showed 284% and 145% bioavailability relative to Lipanthyl® and solid dispersion pellets (FB:PEG = 1:3, respectively. Fluid

  12. Curcumin and Osteosarcoma: Can Invertible Polymeric Micelles Help?

    Directory of Open Access Journals (Sweden)

    Avudaiappan Maran

    2016-06-01

    Full Text Available Systematic review of experimental and clinical data on the use of curcumin in the treatment of osteosarcoma is presented. The current status of curcumin’s therapeutic potential against bone cancer is analyzed in regard to using polymeric micelles (including recently developed invertible, responsive, micelles as a platform for curcumin delivery to treat osteosarcoma. The potential of micellar assemblies from responsive macromolecules in a controlled delivery of curcumin to osteosarcoma cells, and the release using a new inversion mechanism is revealed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Fuguet, Elisabet [Departament de Quimica Analitica, Universitat de Barcelona, Facultat de Quimica, Marti i Franques 1-11, 08028 Barcelona (Spain); Rafols, Clara [Departament de Quimica Analitica, Universitat de Barcelona, Facultat de Quimica, Marti i Franques 1-11, 08028 Barcelona (Spain); Roses, Marti [Departament de Quimica Analitica, Universitat de Barcelona, Facultat de Quimica, Marti i Franques 1-11, 08028 Barcelona (Spain); Bosch, Elisabeth [Departament de Quimica Analitica, Universitat de Barcelona, Facultat de Quimica, Marti i Franques 1-11, 08028 Barcelona (Spain)]. E-mail: e.bosch@ub.edu

    2005-08-29

    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 {approx}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.

  14. 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...

  15. Interaction between zwitterionic surface activity ionic liquid and anionic surfactant: Na(+)-driven wormlike micelles.

    Science.gov (United States)

    Wang, Xiaoqing; Wang, Ruitao; Zheng, Yan; Sun, Limei; Yu, Li; Jiao, Jingjing; Wang, Rui

    2013-02-14

    The physicochemical properties of the mixed zwitterionic surface activity ionic liquid/anionic surfactant (N-alkyl-N'-carboxymethyl imidazolium inner salts/sodium dodecyl sulfate, [N-C(12), N'-CO(2)-Im]/SDS) at various molar ratios (R(1) = C([N-C(12),N'-CO(2)-Im])/(C([N-C(12),N'-CO(2)-Im]) + C(SDS)) were investigated by surface tension and steady-state fluorescence measurements. The results show that the mixed [N-C(12), N'-CO(2)-Im]/SDS system has a much lower cmc value and higher surface activity than individual surfactant. Compared with the mixed zwitterionic betaine surfactant/SDS system, the mixture studied exhibits a stronger synergism, i.e., more negative interaction parameters (β(m) and β(σ)). Through addition of NaCl, the wormlike micelles (WMs) could be formed in a [N-C(12), N'-CO(2)-Im]/SDS system. Steady and dynamic rheology was employed to characterize the WMs with different surfactant ratio (R(1)), NaCl concentration, and temperature. An optimal composition, viz., C(T) = 60 mM, R(1) = 0.45, and C(NaCl) = 0.10 M, was detected to form the strongest and longest wormlike micelles. Compared with the WMs formed by a traditional zwitterionic C(12) betaine/anionic surfactant mixture (e.g., laurylamidopropyl betaine/SDS), the WMs studied have a stronger network structure, which is expected to have potential applications in some fields, such as in nanomaterials synthesis, personal care products, and flooding liquid for tertiary oil recovery.

  16. Role of Synthetic and Dimensional Synthetic Organic Chemistry in Block Copolymer Micelle Nanosensor Engineering

    DEFF Research Database (Denmark)

    Ek, Pramod Kumar

    micelles. Shell cross-linking on PEG-b-PAEMA-b-PS micelles was performed by amidation reactions between the amino groups of PAEMA blocks using a di-carboxylic acid cross-linker. Also a dendritic cross-linker based click chemistry was used to stabilize the PEG-b-PAEMA-b-PES micelle having click readied PES...... micellisation of these functionalized unimers followed by dendritic click shell cross-linking resulted in a stable cRGDfK targeted mixed micelle pH nanosensor. Thus, the engineerability of triblock core-shell-corona micelle was utilized for the synthesis of ratiometric pH nanosensor having desired p...

  17. Biodegradable polymeric micelle-encapsulated doxorubicin suppresses tumor metastasis by killing circulating tumor cells

    Science.gov (United States)

    Deng, Senyi; Wu, Qinjie; Zhao, Yuwei; Zheng, Xin; Wu, Ni; Pang, Jing; Li, Xuejing; Bi, Cheng; Liu, Xinyu; Yang, Li; Liu, Lei; Su, Weijun; Wei, Yuquan; Gong, Changyang

    2015-03-01

    Circulating tumor cells (CTCs) play a crucial role in tumor metastasis, but it is rare for any chemotherapy regimen to focus on killing CTCs. Herein, we describe doxorubicin (Dox) micelles that showed anti-metastatic activity by killing CTCs. Dox micelles with a small particle size and high encapsulation efficiency were obtained using a pH-induced self-assembly method. Compared with free Dox, Dox micelles exhibited improved cytotoxicity, apoptosis induction, and cellular uptake. In addition, Dox micelles showed a sustained release behavior in vitro, and in a transgenic zebrafish model, Dox micelles exhibited a longer circulation time and lower extravasation from blood vessels into surrounding tissues. Anti-tumor and anti-metastatic activities of Dox micelles were investigated in transgenic zebrafish and mouse models. In transgenic zebrafish, Dox micelles inhibited tumor growth and prolonged the survival of tumor-bearing zebrafish. Furthermore, Dox micelles suppressed tumor metastasis by killing CTCs. In addition, improved anti-tumor and anti-metastatic activities were also confirmed in mouse tumor models, where immunofluorescent staining of tumors indicated that Dox micelles induced more apoptosis and showed fewer proliferation-positive cells. There were decreased side effects in transgenic zebrafish and mice after administration of Dox micelles. In conclusion, Dox micelles showed stronger anti-tumor and anti-metastatic activities and decreased side effects both in vitro and in vivo, which may have potential applications in cancer therapy.

  18. Polymeric micelles in anticancer therapy : Targeting, imaging and triggered release

    NARCIS (Netherlands)

    Oerlemans, Chris; Bult, Wouter; Bos, Mariska; Storm, Gert; Nijsen, J. Frank W.; Hennink, Wim E.

    2010-01-01

    Micelles are colloidal particles with a size around 5-100 nm which are currently under investigation as carriers for hydrophobic drugs in anticancer therapy. Currently, five micellar formulations for anticancer therapy are under clinical evaluation, of which Genexol-PM has been FDA approved for use

  19. Monitoring the aggregation of single casein micelles using fluorescence microscopy

    DEFF Research Database (Denmark)

    Bomholt, Julie; Moth-Poulsen, Kasper; Harboe, Marianne

    2011-01-01

    The aggregation of casein micelles (CMs) induced by milk-clotting enzymes is a process of fundamental importance in the dairy industry for cheese production; however, it is not well characterized on the nanoscale. Here we enabled the monitoring of the kinetics of aggregation between single CMs (30...

  20. Complex coacervate core micelles with a lysozyme-modified corona

    NARCIS (Netherlands)

    Danial, M.; Klok, H.A.; Norde, W.; Cohen Stuart, M.A.

    2007-01-01

    This paper describes the preparation, characterization, and enzymatic activity of complex coacervate core micelles (C3Ms) composed of poly(acrylic acid) (PAA) and poly(N-methyl-2-vinyl pyridinium iodide)-b-poly(ethylene oxide) (PQ2VP-PEO) to which the antibacterial enzyme lysozyme is end-attached.

  1. Dynamics of Chain Exchange in Block Copolymer Micelles

    Science.gov (United States)

    Lodge, Timothy

    Block copolymer micelles are rarely at equilibrium. The primary reason is the large number of repeat units in the insoluble block, Ncore, which makes the thermodynamic penalty for extracting a single chain (``unimer exchange'') substantial. As a consequence, the critical micelle concentration (CMC) is rarely accessed experimentally; however, in the proximity of a critical micelle temperature (CMT), equilibration is possible. We have been using time-resolved small angle neutron scattering (TR-SANS) to obtain a detailed picture of the mechanisms and time scales for chain exchange, at or near equilibrium. Our model system is poly(styrene)-block-poly(ethylene-alt-propylene)) (PS-PEP), in the PEP-selective solvent squalane (C30H62) . Equivalent micelles with either normal (hPS) or perdeuterated (dPS) cores are initially mixed in a blend of isotopically substituted squalane, designed to contrast-match a 50:50 hPS:dPS core. Samples are then annealed at a target temperature, and chain exchange is revealed quantitatively by the temporal decay in scattered intensity. The rate of exchange as function of concentration, temperature, Ncore, Ncorona, and chain architecture (diblock versus triblock) will be discussed.

  2. In vivo toxicity of cationic micelles and liposomes

    DEFF Research Database (Denmark)

    Knudsen, Kristina Bram; Northeved, Helle; Ek, Pramod Kumar

    2015-01-01

    This study investigated toxicity of nanocarriers comprised of cationic polymer and lipid components often used in gene and drug delivery, formulated as cationic micelles and liposomes. Rats were injected intravenously with 10, 25 or 100 mg/kg and sacrificed after 24 or 48 h, or 24 h after the last...

  3. Polymeric micelles in anticancer therapy : Targeting, imaging and triggered release

    NARCIS (Netherlands)

    Oerlemans, Chris; Bult, Wouter; Bos, Mariska; Storm, Gert; Nijsen, J. Frank W.; Hennink, Wim E.

    2010-01-01

    Micelles are colloidal particles with a size around 5-100 nm which are currently under investigation as carriers for hydrophobic drugs in anticancer therapy. Currently, five micellar formulations for anticancer therapy are under clinical evaluation, of which Genexol-PM has been FDA approved for use

  4. Structure and flexibility of worm-like micelles

    DEFF Research Database (Denmark)

    Jerke, G.; Pedersen, J.S.; Egelhaaf, S.U.

    1997-01-01

    Small-angle neutron scattering and static light scattering experiments have been performed on worm-like micelles formed by soybean lecithin and trace amounts of water in deuterated iso-octane. The structure and flexibility of the aggregates have been investigated as a function of solution...

  5. 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 s...

  6. Extraction of L-Aspartic Acid with Reverse Micelle System

    Directory of Open Access Journals (Sweden)

    Özlem AYDOĞAN

    2009-02-01

    Full Text Available The aim of this study is to investigate the extraction L-aspartic acid which is a hydrophobic amino acid with reverse micelle system. Production of amino acids by fermentation has been more important in recent years. These amino acids are obtained in dilute aqueous solutions and have to be separated from excess substrate, inorganic salts and by-products. Recently, separation of amino acids from fermentation media by reverse micelle extraction has received a great deal of attention. In this study, reverse micelle phase includes aliquat-336 as a surfactant, 1-decanol as a co-surfactant and isooctane as an apolar solvent. Experiments were performed at 150 rpm stirring rate, at 30 oC, for 30 min extraction time with equal volumes of reverse micelle and aqueous phases. Concentration of L-aspartic acid was analyzed by liquid chromatography (HPLC. The extraction yield increased with increasing pH and aliquat-336 concentration and with decreasing initial amino acid concentration. Maximum ekstraction yield (68 % was obtained at pH of 12, surfactant concentration of 200 mM and an initial amino acid concentration of 5 mM.

  7. Complex coacervation core micelles. Colloidal stability and aggregation mechanism

    NARCIS (Netherlands)

    Burgh, van der S.; Keizer, de A.; Cohen Stuart, M.A.

    2004-01-01

    Complex coacervation core micelles were prepared with various polyelectrolytes and oppositely charged diblock copolymers. The diblock copolymers consist of a charged block and a water-soluble neutral block. Our experimental technique was dynamic light scattering in combination with titrations. At

  8. Complex coacervate core micelles from iron-based coordination polymers.

    Science.gov (United States)

    Wang, Junyou; de Keizer, Arie; Fokkink, Remco; Yan, Yun; Cohen Stuart, Martien A; van der Gucht, Jasper

    2010-07-01

    Complex coacervate core micelles (C3Ms) from cationic poly(N-methyl-2-vinyl-pyridinium iodide)-b-poly(ethylene oxide) (P2MVP(41)-b-PEO(205)) and anionic iron coordination polymers are investigated in the present work. Micelle formation is studied by light scattering for both Fe(II)- and Fe(III)-containing C3Ms. At the stoichiometric charge ratio, both Fe(II)-C3Ms and Fe(III)-C3Ms are stable for at least 1 week at room temperature. Excess of iron coordination polymers has almost no effect on the formed Fe(II)-C3Ms and Fe(III)-C3Ms, whereas excess of P2MVP(41)-b-PEO(205) copolymers in the solution can dissociate the formed micelles. Upon increasing salt concentration, the scattering intensity decreases. This decrease is due to both a decrease in the number of micelles (or an increase in CMC) and a decrease in aggregation number. The salt dependence of the CMC and the aggregation number is explained using a scaling argument for C3M formation. Compared with Fe(II)-C3Ms, Fe(III)-C3Ms have a lower CMC and a higher stability against dissociation by added salt.

  9. Molecular dynamics simulation of a polysorbate 80 micelle in water

    NARCIS (Netherlands)

    Amani, Amir; York, Peter; de Waard, Hans; Anwar, Jamshed

    2011-01-01

    The structure and dynamics of a single molecule of the nonionic surfactant polysorbate 80 (POE (20) sorbitan monooleate; Tween 80 (R)) as well as a micelle comprising sixty molecules of polysorbate 80 in water have been investigated by molecular dynamics simulation. In its free state in water the po

  10. Casein Micelles: Size Distribution in Milks from Individual Cows

    NARCIS (Netherlands)

    de Kruif, C.G.; Huppertz, T.

    2012-01-01

    The size distribution and protein composition of casein micelles in the milk of Holstein-Friesian cows was determined as a function of stage and number of lactations. Protein composition did not vary significantly between the milks of different cows or as a function of lactation stage. Differences i

  11. Biochemical characterization of GM1 micelles-Amphotericin B interaction.

    Science.gov (United States)

    Leonhard, Victoria; Alasino, Roxana V; Bianco, Ismael D; Garro, Ariel G; Heredia, Valeria; Beltramo, Dante M

    2015-01-01

    In this work a thorough characterization of the GM1 micelle-Amphotericin B (AmB) interaction was performed. The micelle formation as well as the drug loading occurs spontaneously, although influenced by the physicochemical conditions, pH and temperature. The chromatographic profile of GM1-AmB complexes at different molar ratios shows the existence of two populations. The differential absorbance of GM1, monomeric and aggregate AmB, allowed us to discriminate the presence of all of them in both fractions. Thus, we noted that at higher proportion of AmB in the complex, increases the larger population which is composed mainly of aggregated AmB. The physical behavior of these micelles shows that both GM1- AmB complexes were stable in solution for at least 30 days. However upon freeze-thawing or lyophilization-solubilization cycles, only the smallest population, enriched in monomeric AmB, showed a complete solubilization. In vitro, GM1-AmB micelles were significantly less toxic on cultured cells than other commercial micellar formulations as Fungizone, but had a similar behavior to liposomal formulations as Ambisome. Regarding the antifungal activity of the new formulation, it was very similar to that of other formulations. The characterization of these GM1-AmB complexes is discussed as a potential new formulation able to improve the antifungal therapeutic efficiency of AmB.

  12. Kinetic investigation of the oxidation of N-alkyl anilines by peroxomonophosphoric acid in anionic surfactant sodium lauryl sulphate

    Indian Academy of Sciences (India)

    G P Panigrahi; Jagannath Panda

    2000-12-01

    Kinetics of oxidation of N-methyl and N-ethyl aniline by peroxomono-phosphoric acid (PMPA) in aqueous and 5% (v/v) acetonitrile medium respectively have been studied in presence of anionic micelles of sodium lauryl sulphate (SLS) at different H. Oxidation rate of both the substrates increases up to a certain [SLS] much below the critical micellar concentration (cmc) after which the rate is retarded. Kinetic data have been used to compute the binding constants of both substrate and oxidant with the micelle. A scheme explaining the kinetic data has been proposed.

  13. Targeted therapy of colorectal neoplasia with rapamycin in peptide-labeled pegylated octadecyl lithocholate micelles.

    Science.gov (United States)

    Khondee, Supang; Rabinsky, Emily F; Owens, Scott R; Joshi, Bishnu P; Qiu, Zhen; Duan, Xiyu; Zhao, Lili; Wang, Thomas D

    2015-02-10

    Many powerful drugs have limited clinical utility because of poor water solubility and high systemic toxicity. Here, we formulated a targeted nanomedicine, rapamycin encapsulated in pegylated octadecyl lithocholate micelles labeled with a new ligand for colorectal neoplasia, LTTHYKL peptide. CPC;Apc mice that spontaneously develop colonic adenomas were treated with free rapamycin, plain rapamycin micelles, and peptide-labeled rapamycin micelles via intraperitoneal injection for 35days. Endoscopy was performed to monitor adenoma regression in vivo. We observed complete adenoma regression at the end of therapy. The mean regression rate for peptide-labeled rapamycin micelles was significantly greater than that for plain rapamycin micelles, Prapamycin micelles compared to that of free drug, and no other toxicities were found on chemistries. Together, this unique targeted micelle represents a potential therapeutic for colorectal neoplasia with comparable therapeutic efficacy to rapamycin free drug and significantly less systemic toxicity.

  14. Polymeric micelles based on poly(ethylene oxide) and α-carbon substituted poly(ɛ-caprolactone): An in vitro study on the effect of core forming block on polymeric micellar stability, biocompatibility, and immunogenicity.

    Science.gov (United States)

    Garg, Shyam M; Vakili, Mohammad Reza; Lavasanifar, Afsaneh

    2015-08-01

    A series of block copolymers based on methoxy poly(ethylene oxide)-block-poly(ɛ-caprolactone) (PEO-b-PCL), PEO-b-PCL bearing side groups of benzyl carboxylate (PEO-b-PBCL), or free carboxyl (PEO-b-PCCL) on the PCL backbone with increasing degrees of polymerization of the PCL backbone were synthesized. Prepared block copolymers assembled to polymeric micelles by co-solvent evaporation. The physical stability of prepared micelles was assessed by measuring their tendency toward aggregation over time using dynamic light scattering (DLS). The resistance of micelles against dissociation in the presence of a micelle destabilizing agent, i.e., sodium dodecyl sulfate (SDS), was also investigated using DLS. The rate of micellar core degradation was determined using (1)H NMR for polymer molecular weight measurement upon incubation of micelles in PBS (pH=7.4) at 37°C followed by dialysis of the remaining polymer at different time intervals. The effect of pendent group chemistry in the micellar core on the adsorption of serum proteins to micellar structure was then evaluated using Bradford Protein assay kit. Finally, the effect of micellar core structure on the induction of bone marrow derived dendritic cell (BMDC) maturation and secretion of IL-12 was studied as a measure of micellar immunogenicity. The results showed micelle structures from polymers with higher degree of polymerization in the hydrophobic block and/or those with more hydrophobic substituents on the core-forming block, to be more stable. This was reflected by a decreased tendency for micellar aggregation, reduced dissociation of micelles in the presence of SDS, and diminished core degradation. All micelles were shown to have insignificant adsorption of serum protein suggesting that the hydrophilic PEO shell provided sufficient protection of the core. However, the protein adsorption increased with increase in the hydrophobicity and molecular weight of the core-forming block. Irrespective of the micellar core

  15. Bile salt/phospholipid mixed micelle precursor pellets prepared by fluid-bed coating.

    Science.gov (United States)

    Dong, Fuxia; Xie, Yunchang; Qi, Jianping; Hu, Fuqiang; Lu, Yi; Li, Sanming; Wu, Wei

    2013-01-01

    Bile salt/phospholipid mixed micelles (MMs) are potent carriers used for oral absorption of drugs that are poorly soluble in water; however, there are many limitations associated with liquid formulations. In the current study, the feasibility of preparing bile salt/phospholipid MM precursor (preMM) pellets with high oral bioavailability, using fluid-bed coating technology, was examined. In this study, fenofibrate (FB) and sodium deoxycholate (SDC) were used as the model drug and the bile salt, respectively. To prepare the MMs and to serve as the micellular carrier, a weight ratio of 4:6 was selected for the sodium deoxycholate/phospholipids based on the ternary phase diagram. Polyethylene glycol (PEG) 6000 was selected as the dispersion matrix for precipitation of the MMs onto pellets, since it can enhance the solubilizing ability of the MMs. Coating of the MMs onto the pellets using the fluid-bed coating technology was efficient and the pellets were spherical and intact. MMs could be easily reconstituted from preMM pellets in water. Although they existed in a crystalline state in the preMM pellets, FB could be encapsulated into the reconstituted MMs, and the MMs were redispersed better than solid dispersion pellets (FB:PEG = 1:3) and Lipanthyl®. The redispersibility of the preMM pellets increased with the increase of the FB/PEG/micellar carrier. PreMM pellets with a FB:PEG:micellar carrier ratio of 1:1.5:1.5 showed 284% and 145% bioavailability relative to Lipanthyl® and solid dispersion pellets (FB:PEG = 1:3), respectively. Fluid-bed coating technology has considerable potential for use in preparing sodium deoxycholate/phospholipid preMM pellets, with enhanced oral bioavailability for poorly water-soluble drugs.

  16. Structural micellar transition for fluorinated and hydrogenated sodium carboxylates induced by solubilization of benzyl alcohol.

    Science.gov (United States)

    González-Pérez, Alfredo; Ruso, Juan M; Prieto, Gerardo; Sarmiento, Félix

    2004-09-28

    The solubility of benzyl alcohol in micellar solutions of sodium octanoate and sodium perfluorooctanoate was studied. From the isotherms of specific conductivity versus molality at different alcohol concentrations, the critical micelle concentration and the degree of ionization of the micelles were determined. The cmc linearly decreases upon increasing the amount of benzyl alcohol present in aqueous solutions with two distinct slopes. This phenomenon was interpreted as a clustering of alcohol molecules above a critical point, around 0.1 mol kg(-1). Attending to the equivalent conductivity versus square root of molality, the presence of a second micellar structure for the fluorinated compound was assumed. The thermodynamic parameters associated with the process of micellization were estimated by applying Motomura's model for binary surfactant mixtures, modified by Pérez-Villar et al. (Colloid Polym. Sci 1990, 268, 965) for the case of alcohol-surfactant solutions. A comparison of the hydrogenated and fluorinated compounds was carried out and discussed.

  17. Electrochemical Oxidation of L-Cysteine in Sodium Dodecyl Sulfate Admicelles

    Institute of Scientific and Technical Information of China (English)

    李中春; 刘天晴; 郭荣

    2005-01-01

    The electrochemical oxidation of L-cysteine can be catalyzed by sodium dodecyl sulfate (SDS) admicelles. The catalytic efficiency increases hardly when SDS concentration is lower than the critical admicelle concentration (CAC) and increases rapidly when SDS concentration is between CAC and the critical micelle concentration (CMC), but decreases when SDS concentration is higher than CMC. Both results of rate constant k0 and Gibbs free energy ΔGck accord with that of catalytic efficiency.

  18. Radiolabeling of liposomes and polymeric micelles with PET-isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ingemann Jensen, A.T.

    2013-06-01

    This thesis is divided into three separate chapters that can be read independently. Chapter 1 is a general introduction, touching upon liposomes and polymeric micelles and radiolabeling with 18F and 64Cu. Chapter 2 and 3 address two separate research projects, each described below. A complete reference list is compiled in the end, immediately after the three chapters. This is followed by the supplementary information, divided into appropriate sections. Finally, the two first-authored manuscripts are attached as appendices. Chapter 1. The field of nanoparticulate drug delivery has been hailed as a revolution in modern therapeutics, especially in chemotherapy. A major reason is the ability of nanoparticles to accumulate in tumor tissue. Liposomes are the classic nanoparticle, consisting of a lipid membrane with an aqueous core. Polymeric micelles are made from amphiphilic detergent-like copolymers, that self-assemble in water. Therapy with nanoparticles is hampered by often poor tumor accumulation, combined with massive uptake by macrophages in the liver and spleen. For this reason, visualizing nanoparticle pharmacokinetics in-vivo is a valuable tool in the on-going research. Such visualization can be done by labeling with radio isotopes. Isotopes that emit positrons (PET-isotopes) can be detected by PET (positron emission tomography) technology, an accurate technique that has gained popularity in recent years. PET-isotopes of interest include 18F and 64Cu. In addition to being a research tool, radiolabeled nanoparticles hold promise as a radiopharmaceutical in themselves, as a means of imaging tumor tissue, aiding in diagnosis and surgery. Chapter 2. A method for labeling liposomes with 18F (97% positron decay, T = 110 min) was investigated. 18F is widely available, but is hampered by a short half-life only allowing up to 8 hours scans. 18F must be covalently attached to components of the liposome. By binding to a lipid, it can be stably lodged in the membrane. A

  19. Determination of ofloxacin and gatifloxacin by mixed micelle-mediated cloud point extraction-fluorimetry combined methodology

    Science.gov (United States)

    Wu, Hao; Zhao, Guo-yan; Du, Li-ming

    2010-05-01

    A cloud point extraction process using mixed micelle of the anionic surfactant sodium dodecyl sulfate (SDS) and the non-ionic surfactant polyoxyethylene(7.5)nonylphenylether (PONPE 7.5) to extract two fluoroquinolone antimicrobial agents, ofloxacin and gatifloxacin, from aqueous media was investigated. The method is based on the mixed micelle-mediated extraction of fluoroquinolones in the presence of NaCl as an inducing agent in phase separation, followed by spectrofluorimetric determination. The effect of different variables such as pH, PONPE7.5 concentration, SDS concentration, NaCl concentration, cloud point temperature, and time was investigated, and optimum conditions were established. At optimum conditions, the rectilinear calibration graphs were obtained in the concentration range of 0.1-150 and 0.1-250 ng mL -1 for ofloxacin and gatifloxacin, and the limits of detection were 0.04 and 0.06 ng mL -1, respectively. The proposed procedure was applied successfully for the detection of the investigated drugs in their pharmaceutical dosage forms, in spiked plasma, spiked urine, and urine samples, with good precision and accuracy.

  20. Development of separation systems for polynuclear aromatic hydrocarbon environmental contaminants using micellar electrokinetic chromatography with molecular micelles and free zone electrophoresis.

    Science.gov (United States)

    Moy, T W; Ferguson, P L; Grange, A H; Matchett, W H; Kelliher, V A; Brumley, W C; Glassman, J; Farley, J W

    1998-09-01

    Of four systems available from the literature, based on cyclodextrins, dioctylsulfosuccinate, bile salts, and molecular micelles consisting of oligomers of undecylenic acid, the most successful separation system in our hands is based on the molecular micelles, oligomers of sodium undecylenic acid (OSUA). We have employed organic additives of acetonitrile, acetone, and tetrahydrofuran in achieving separations of polyaromatic hydrocarbons (PNAs) using molecular micelles. Generally, successful separations are achieved with 20-40% composition as the organic additive in an 8 mM borate buffer. We separated 16 PNAs with 20% tetrahydrofuran in a system of 8 mM borate and 0.125 g/10 mL (ca. 6.25 mM) of OSUA. Typical extracts of environmental samples contain additional analytes besides the typical 16 target compounds. Among these are the nitrogen-containing aromatics that can act as cations under conditions of low pH and additional compounds that can act as anions under basic conditions in free-zone electrophoresis. These additional classes of analytes are separated by capillary zone electrophoresis/laser-induced fluorescence detection using a frequency-doubled laser operated at 257 nm.

  1. 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.

  2. Effects of architecture on the stability of thermosensitive unimolecular micelles.

    Science.gov (United States)

    Steinschulte, Alexander A; Schulte, Bjoern; Rütten, Stephan; Eckert, Thomas; Okuda, Jun; Möller, Martin; Schneider, Stefanie; Borisov, Oleg V; Plamper, Felix A

    2014-03-14

    The influence of architecture on polymer interactions is investigated and differences between branched and linear copolymers are found. A comprehensive picture is drawn with the help of a fluorescence approach (using pyrene and 4HP as probe molecules) together with IR or NMR spectroscopy and X-ray/light scattering measurements. Five key aspects are addressed: (1) synergistic intramolecular complexation within miktoarm stars. The proximity of thermoresponsive poly(propylene oxide) (PPO) and poly(dimethylaminoethyl methacrylate) (PDMAEMA) within a miktoarm star leads to complexation between these weakly interacting partners. Consequently, the original properties of the constituents are lost, showing hydrophobic domains even at low temperatures, at which all homopolymers are water soluble. (2) Unimolecular micelles for miktoarm stars. The star does not exhibit intermolecular self-assembly in a large temperature range, showing unimers up to 55 °C. This behavior was traced back to a reduced interfacial tension between the PPO-PDMAEMA complex and water (PDMAEMA acts as a "microsurfactant"). (3) Unimolecular to multimolecular micelle transition for stars. The otherwise stable unimolecular micelles self-assemble above 55 °C. This aggregation is not driven by PPO segregation, but by collapse of residual PDMAEMA. This leads to micrometer-sized multilamellar vesicles stabilized by poly(ethylene oxide) (PEO). (4) Prevention of pronounced complexation within diblock copolymers. In contrast to the star copolymers, PPO and PDMAEMA adapt rather their homopolymer behavior within the diblock copolymers. Then they show their immanent LCST properties, as PDMAEMA turns insoluble at elevated temperatures, whereas PPO becomes hydrophobic below room temperature. (5) Two-step micellization for diblock copolymers. Upon heating of linear copolymers, the dehydration of PPO is followed by self-assembly into spherical micelles. An intermediate prevalence of unimolecular micelles is revealed

  3. Two distinct mechanisms of vesicle-to-micelle and micelle-to-vesicle transition are mediated by the packing parameter of phospholipid-detergent systems

    NARCIS (Netherlands)

    Stuart, Marc C. A.; Boekema, Egbert J.

    2007-01-01

    The detergent solubilization and reformation of phospholipid vesicles was studied for various detergents. Two distinct mechanisms of vesicle-to-micelle and micelle-to-vesicle transition were observed by turbidimetry and cryo-electron microscopy. The first mechanism involves fast solubilization of ph

  4. Large magnetic anisotropy in ferrihydrite nanoparticles synthesized from reverse micelles

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, E L [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, Sao Paulo, 05315-970 (Brazil); Itri, R [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, Sao Paulo, 05315-970 (Brazil); Jr, E Lima [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, Sao Paulo, 05315-970 (Brazil); Baptista, M S [Instituto de Quimica, Universidade de Sao Paulo, Avenida Professor Lineu Prestes 748, Sao Paulo (Brazil); Berquo, T S [Institute for Rock Magnetism, University of Minnesota, 100 Union Street SE, Minneapolis, MN 55455-0128 (United States); Goya, G F [Instituto de Nanociencias de Aragon (INA), Universidad de Zaragoza, Pedro Cerbuna 12 (50009), Zaragoza (Spain)

    2006-11-28

    Six-line ferrihydrite (FH) nanoparticles have been synthesized in the core of reverse micelles, used as nanoreactors to obtain average particle sizes {approx} 2-4 nm. The blocking temperatures T{sub B}{sup m} extracted from magnetization data increased from {approx}10 to 20 K for increasing particle size. Low-temperature Moessbauer measurements allowed us to observe the onset of differentiated contributions from the particle core and surface as the particle size increases. The magnetic properties measured in the liquid state of the original emulsion showed that the ferrihydrite phase is not present in the liquid precursor, but precipitates in the micelle cores after the free water is freeze-dried. Systematic susceptibility {chi}{sub ac}(f,T) measurements showed the dependence of the effective magnetic anisotropy energies E{sub a} with particle volume, and yielded an effective anisotropy value of K{sub eff} = 312 {+-} 10 kJ m{sup -3}.

  5. Flavonoid glycosides from Persea caerulea. Unraveling their interactions with SDS-micelles through matrix-assisted DOSY, PGSE, mass spectrometry, and NOESY.

    Science.gov (United States)

    Álvarez, Juan M; Raya-Barón, Álvaro; Nieto, Pedro M; Cuca, Luis E; Carrasco-Pancorbo, Alegría; Fernández-Gutiérrez, Alberto; Fernández, Ignacio

    2016-04-13

    Two flavonoid glycosides derived from rhamnopyranoside (1) and arabinofuranoside (2) have been isolated from leaves of Persea caerulea for the first time. The structures of 1 and 2 have been established by (1) H NMR, (13) C NMR, and IR spectroscopy, together with LC-ESI-TOF and LC-ESI-IT MS spectrometry. From the MS and MS/MS data, the molecular weights of the intact molecules as well as those of quercetin and kaempferol together with their sugar moieties were deduced. The NMR data provided information on the identity of the compounds, as well as the α and β configurations and the position of the glycosides on quercetin and kaempferol. We have also explored the application of sodium dodecyl sulfate (SDS) normal micelles in binary aqueous solution, at a range of concentrations, to the diffusion resolution of these two glycosides, by the application of matrix-assisted diffusion ordered spectroscopy (DOSY) and pulse field gradient spin echo (PGSE) methodologies, showing that SDS micelles offer a significant resolution which can, in part, be rationalized in terms of differing degrees of hydrophobicity, amphiphilicity, and steric effects. In addition, intra-residue and inter-residue proton-proton distances using nuclear Overhauser effect build-up curves were used to elucidate the conformational preferences of these two flavonoid glycosides when interacting with the micelles. By the combination of both diffusion and nuclear Overhauser spectroscopy techniques, the average location site of kaempferol and quercetin glycosides has been postulated, with the former exhibiting a clear insertion into the interior of the SDS-micelle, whereas the latter is placed closer to the surface. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Biosensors with reversed micelle-enzyme sensitive membrane

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effect of reversed micelle on the conformation of enzyme was studied by sensor techniques. By means of measurement of the response current of GOD enzyme membrane electrode, the effects of enzyme embedded in AOT reversed micellar on GOD conformation and catalytic activity are discussed. The results show that the response current increased greatly with decreasing ratio of GOD/AOT, meaning that the catalytic activity and the conformation stability of enzyme were enhanced.

  7. Gold-Loaded Polymeric Micelles with Temperature-Modulated Catalytic Activity

    Institute of Scientific and Technical Information of China (English)

    HU Na; SHI Dongjian; LI Jihang; LI Junfeng; CHEN Mingqing

    2015-01-01

    Four-armed amphiphilic block copolymers, polystyrene-b-poly(N-isopropylacrylamide) (PS-b-PNIPAM)4, were synthesized by atom transfer radical polymerization (ATRP). (PS-b-PNIPAM)4 self-assembled into micelles with PS block as core and thermoresponsive PNIPAM block as corona. The gold nanoparticles (Au NPs) with average diameter about 5.8 nm were immobilized on the surfaces of the micelles by the reduction of the corresponding ions. The micelle-supported gold nanoparticles (Au-micelles) were applied to catalyze the reduction ofp-nitrophenol. Moreover, the activity of the Au-micelle catalyst could be modulated by the temperature and the Au-micelles could be easily recovered by changing the temperature and recycled four times with high catalytic activity.

  8. Construction of the Active Site of Metalloenzyme on Au NC Micelles

    Institute of Scientific and Technical Information of China (English)

    ZHANG, Zhiming; FU, Qiuan; HUANG, Xin; XU, Jiayun; LIU, Junqiu; SHEN, Jiacong

    2009-01-01

    For developing an efficient nanoenzyme system with self-assembly strategy, gold nanocrystal micelles (Au NC micelles) with inserted catalytic Zn(Ⅱ) centers were constructed by self-assembly of a catalytic ligand [N,N-bis(2-aminoethyl)-N'dodecylethylenediamine] Zn(Ⅱ) complexes (Zn(Ⅱ)L) on the surface of Au NC via hy- drophobic interaction. The functionalized Au NC micelles acted as an excellent nanoenzyme model for imitating ribonuclease. The catalytic capability of the Au NC micelles was evaluated by accelerating the cleavage of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP). These functionalized Au NC micelles exhibited considerable ri- bonuclease-like activities by a factor of 4.9×104 (kcat/kuncat) for the cleavage of HPNP in comparison to the sponta- neous cleavage of HPNP at 37℃. The catalytic capability of the functionalized Au NC micelles can be considera- bly compared to other models reported previously as nanoenzymes under the comparable conditions.

  9. Development of the simple and sensitive method for lipoxygenase assay in AOT/isooctane reversed micelles.

    Science.gov (United States)

    Park, Kyung Min; Kim, Yu Na; Choi, Seung Jun; Chang, Pahn-Shick

    2013-06-01

    In this study, we investigated the possibility of reversed micelles, widely used as an enzyme reactor for lipases, for the determination of lipoxygenase activity. Although it is rapid and simple, reversed micelles have some limitations, such as interference by UV-absorbing materials and surfactant. Lipoxygenase activity in the reversed micelles was determined by reading the absorbance of the lipid hydroperoxidation product (conjugated diene) at 234 nm. Among surfactants and organic media, AOT and isooctane were most effective for the dioxygenation of linoleic acid in reversed micelles. The strong absorbance of AOT in the UV region is a major obstacle for the direct application of the AOT/isooctane reversed micelles to lipoxygenase activity determination. To prevent interference by AOT, we added an AOT removal step in the procedure for lipoxygenase activity determination in reversed micelles. The lipoxygenase activity was dependent on water content, and maximum activity was obtained at an R-value of 10.

  10. Predicting proton titration in cationic micelle and bilayer environments

    Energy Technology Data Exchange (ETDEWEB)

    Morrow, Brian H.; Shen, Jana K. [Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201 (United States); Eike, David M.; Murch, Bruce P.; Koenig, Peter H. [Computational Chemistry, Modeling and Simulation GCO, Procter and Gamble, Cincinnati, Ohio 45201 (United States)

    2014-08-28

    Knowledge of the protonation behavior of pH-sensitive molecules in micelles and bilayers has significant implications in consumer product development and biomedical applications. However, the calculation of pK{sub a}’s in such environments proves challenging using traditional structure-based calculations. Here we apply all-atom constant pH molecular dynamics with explicit ions and titratable water to calculate the pK{sub a} of a fatty acid molecule in a micelle of dodecyl trimethylammonium chloride and liquid as well as gel-phase bilayers of diethyl ester dimethylammonium chloride. Interestingly, the pK{sub a} of the fatty acid in the gel bilayer is 5.4, 0.4 units lower than that in the analogous liquid bilayer or micelle, despite the fact that the protonated carboxylic group is significantly more desolvated in the gel bilayer. This work illustrates the capability of all-atom constant pH molecular dynamics in capturing the delicate balance in the free energies of desolvation and Coulombic interactions. It also shows the importance of the explicit treatment of ions in sampling the protonation states. The ability to model dynamics of pH-responsive substrates in a bilayer environment is useful for improving fabric care products as well as our understanding of the side effects of anti-inflammatory drugs.

  11. Polymeric micelles encapsulating photosensitizer: structure/photodynamic therapy efficiency relation.

    Science.gov (United States)

    Gibot, Laure; Lemelle, Arnaud; Till, Ugo; Moukarzel, Béatrice; Mingotaud, Anne-Françoise; Pimienta, Véronique; Saint-Aguet, Pascale; Rols, Marie-Pierre; Gaucher, Mireille; Violleau, Frédéric; Chassenieux, Christophe; Vicendo, Patricia

    2014-04-14

    Various polymeric micelles were formed from amphiphilic block copolymers, namely, poly(ethyleneoxide-b-ε-caprolactone), poly(ethyleneoxide-b-d,l-lactide), and poly(ethyleneoxide-b-styrene). The micelles were characterized by static and dynamic light scattering, electron microscopy, and asymmetrical flow field-flow fractionation. They all displayed a similar size close to 20 nm. The influence of the chemical structure of the block copolymers on the stability upon dilution of the polymeric micelles was investigated to assess their relevance as carriers for nanomedicine. In the same manner, the stability upon aging was assessed by FRET experiments under various experimental conditions (alone or in the presence of blood proteins). In all cases, a good stability over 48 h for all systems was encountered, with PDLLA copolymer-based systems being the first to release their load slowly. The cytotoxicity and photocytotoxicity of the carriers were examined with or without their load. Lastly, the photodynamic activity was assessed in the presence of pheophorbide a as photosensitizer on 2D and 3D tumor cell culture models, which revealed activity differences between the 2D and 3D systems.

  12. Hydrotropy: monomer-micelle equilibrium and minimum hydrotrope concentration.

    Science.gov (United States)

    Shimizu, Seishi; Matubayasi, Nobuyuki

    2014-09-01

    Drug molecules with low aqueous solubility can be solubilized by a class of cosolvents, known as hydrotropes. Their action has often been explained by an analogy with micelle formation, which exhibits critical micelle concentration (CMC). Indeed, hydrotropes also exhibit "minimum hydrotrope concentration" (MHC), a threshold concentration for solubilization. However, MHC is observed even for nonaggregating monomeric hydrotropes (such as urea); this raises questions over the validity of this analogy. Here we clarify the effect of micellization on hydrotropy, as well as the origin of MHC when micellization is not accompanied. On the basis of the rigorous Kirkwood-Buff (KB) theory of solutions, we show that (i) micellar hydrotropy is explained also from preferential drug-hydrotrope interaction; (ii) yet micelle formation reduces solubilization effeciency per hydrotrope molecule; (iii) MHC is caused by hydrotrope-hydrotrope self-association induced by the solute (drug) molecule; and (iv) MHC is prevented by hydrotrope self-aggregation in the bulk solution. We thus need a departure from the traditional view; the structure of hydrotrope-water mixture around the drug molecule, not the structure of the aqueous hydrotrope solutions in the bulk phase, is the true key toward understanding the origin of MHC.

  13. Micelles and nanoparticles for ultrasonic drug and gene delivery.

    Science.gov (United States)

    Husseini, Ghaleb A; Pitt, William G

    2008-06-30

    Drug delivery research employing micelles and nanoparticles has expanded in recent years. Of particular interest is the use of these nanovehicles that deliver high concentrations of cytotoxic drugs to diseased tissues selectively, thus reducing the agent's side effects on the rest of the body. Ultrasound, traditionally used in diagnostic medicine, is finding a place in drug delivery in connection with these nanoparticles. In addition to their non-invasive nature and the fact that they can be focused on targeted tissues, acoustic waves have been credited with releasing pharmacological agents from nanocarriers, as well as rendering cell membranes more permeable. In this article, we summarize new technologies that combine the use of nanoparticles with acoustic power both in drug and gene delivery. Ultrasonic drug delivery from micelles usually employs polyether block copolymers and has been found effective in vivo for treating tumors. Ultrasound releases drug from micelles, most probably via shear stress and shock waves from the collapse of cavitation bubbles. Liquid emulsions and solid nanoparticles are used with ultrasound to deliver genes in vitro and in vivo. The small packaging allows nanoparticles to extravasate into tumor tissues. Ultrasonic drug and gene delivery from nanocarriers has tremendous potential because of the wide variety of drugs and genes that could be delivered to targeted tissues by fairly non-invasive means.

  14. Chain exchange kinetics of block copolymer micelles in ionic liquids

    Science.gov (United States)

    Ma, Yuanchi; Lodge, Timothy

    The chain exchange kinetics of block copolymer micelles has been studied using time-resolved small-angle neutron scattering (TR-SANS), a key tool in determining the average micelle composition in contrast-matched solvents. In this work, PMMA-block-PnBMA was selected as the model block copolymer, which has a LCST behavior in the common ionic liquids, [EMIM][TFSI] and [BMIM][TFSI]. We examined the chain exchange kinetics of three PMMA-block-PnBMA copolymers, with identical PMMA block length (MPMMA = 25000) and different PnBMA block lengths (MPnBMA = 24000, 35000 and 53000); the Flory-Huggins interaction parameter (χ) between the core (PnBMA) and the solvent were varied by mixing [EMIM][TFSI] and [BMIM][TFSI] in different ratios. We found that the relaxation of the initial segregation of h- and d- micelles followed the same form with the time as previously developed by our group. Assuming that single chain expulsion is the rate limiting step, the thermal barrier was found to depend linearly on the core block length (Ncore) . Furthermore, the effect of χ on the chain exchange kinetics will also be discussed.

  15. Enhancing oral bioavailability of quercetin using novel soluplus polymeric micelles

    Science.gov (United States)

    Dian, Linghui; Yu, Enjiang; Chen, Xiaona; Wen, Xinguo; Zhang, Zhengzan; Qin, Lingzhen; Wang, Qingqing; Li, Ge; Wu, Chuanbin

    2014-12-01

    To improve its poor aqueous solubility and stability, the potential chemotherapeutic drug quercetin was encapsulated in soluplus polymeric micelles by a modified film dispersion method. With the encapsulation efficiency over 90%, the quercetin-loaded polymeric micelles (Qu-PMs) with drug loading of 6.7% had a narrow size distribution around mean size of 79.00 ± 2.24 nm, suggesting the complete dispersibility of quercetin in water. X-ray diffraction (XRD) patterns illustrated that quercetin was in amorphous or molecular form within PMs. Fourier transform infrared spectroscopy (FTIR) indicated that quercetin formed intermolecular hydrogen bonding with carriers. An in vitro dialysis test showed the Qu-PMs possessed significant sustained-release property, and the formulation was stable for at least 6 months under accelerated conditions. The pharmacokinetic study in beagle dogs showed that absorption of quercetin after oral administration of Qu-PMs was improved significantly, with a half-life 2.19-fold longer and a relative oral bioavailability of 286% as compared to free quercetin. Therefore, these novel soluplus polymeric micelles can be applied to encapsulate various poorly water-soluble drugs towards a development of more applicable therapeutic formulations.

  16. Infrared spectrophotometric analysis of acidified aqueous sodium oleate solutions

    Science.gov (United States)

    Drzymala, Jan; Kielkowska, M. M.

    Infrared spectroscopy was applied to the analysis of 10 -3 M aqueous sodium oleate solutions titrated with 0.2 M HCl. From characteristic absorption bands of sodium oleate at 1560 cm -1 and oleic acid at 1710 cm -1 the degree of oleate ion neutralization in the titrated system at varying pH was calculated.It was found that the pH-metric titration curve of oleate ions differs considerably from the theoretical curve calculated for the reaction Ol -aq + H + = HOl liq, taking the solubility product of oleic acid equal to 12.5. Most likely aggregates of oleate ons (micelles) are formed during titration and account for the deviation of the titration curves from theory.

  17. Microwave-assisted Palladium-micelle-catalyzed Suzuki Cross-coupling Reaction in Water

    Institute of Scientific and Technical Information of China (English)

    LIN Li; LI Sheng-hai; JIANG Ri-hua

    2011-01-01

    A microwave-accelerated Suzuki coupling procedure was developed via guanidinium ionic liquids(GILs)stabilized Pd-micelle.The Pd micelle/GILs play a key role in enhancing the activity,due to the highly dispersed Pd active sites and the phase transfer function of GILs,which ensures the adsorption of reactants and facilitates the translation of the intermediates to the surface of the micelle.

  18. Structure of phosphate fluorosurfactant based reverse micelles in supercritical carbon dioxide

    OpenAIRE

    Senapati, S; Keiper, J. S.; de Simone, J. M.; Wignall, G. D.; Melnichenko, Y. B.; Frielinghaus, H; Berkowitz, M. L.

    2002-01-01

    The existence of microemulsions in the system composed of phosphate-based fluorosurfactant, water, and supercritical CO2 is demonstrated by small-angle neutron scattering experiments. A computer simulation study performed on a reverse micelle created in this system shows that the micelle remains stable over a 4 ns time period of the simulation. While the data obtained from the experiments provide information about the size of the reverse micelle, the data obtained from the simulations provide...

  19. How to Squeeze a Sponge: Casein Micelles under Osmotic Stress, a SAXS Study

    OpenAIRE

    Bouchoux, Antoine; Gésan-Guiziou, Geneviève; Pérez, Javier; Cabane, Bernard

    2010-01-01

    By combining the osmotic stress technique with small-angle x-ray scattering measurements, we followed the structural response of the casein micelle to an overall increase in concentration. When the aqueous phase that separates the micelles is extracted, they behave as polydisperse repelling spheres and their internal structure is not affected. When they are compressed, the micelles lose water and shrink to a smaller volume. Our results indicate that this compression is nonaffine, i.e., some p...

  20. 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.

  1. 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.

  2. Molecular Dynamics Simulations of Cytochrome c un-folding in AOT Reverse Micelles: the first steps

    CERN Document Server

    Abel, Stéphane; Marchi, Massimo

    2009-01-01

    This paper explores the reduced form of horse cytochrome c confined in reverse micelles (RM) of so-dium bis-(2-ethylhexyl) sulfosuccinate (AOT) in isooctane by molecular dynamics simulation. RMs of two sizes were constructed at a water content of Wo = [H2O]/[AOT] = 5.5 and 9.1. Our results show that the protein secondary structure and the heme conformation both depend on micellar hydration. At low hydration, the protein structure and the heme moiety remain stable, whereas at high water content the protein becomes unstable and starts to unfold. At Wo = 9.1, according to the X-ray structure, conforma-tional changes are mainly localized on protein loops and around the heme moiety, where we observe a partial opening of the heme crevice. These findings suggest that within our time window (10 ns), the structural changes observed at the heme level are the first steps of the protein denaturation process, pre-viously described experimentally in micellar solutions. In addition, a specific binding of AOT molecules to a ...

  3. Synthesis of single-walled carbon nanotube networks using monodisperse metallic nanocatalysts encapsulated in reverse micelles

    Directory of Open Access Journals (Sweden)

    Gayduchenko Igor A.

    2016-01-01

    Full Text Available We report on a method of synthesis of single-walled carbon nanotubes percolated networks on silicon dioxide substrates using monodisperse Co and Ni catalyst. The catalytic nanoparticles were obtained by modified method of reverse micelles of bis-(2-ethylhexyl sulfosuccinate sodium in isooctane solution that provides the nanoparticle size control in range of 1 to 5 nm. The metallic nanoparticles of Ni and Co were characterized using transmission electron microscopy (TEM and atomic-force microscopy (AFM. Carbon nanotubes were synthesized by chemical vapor deposition of CH4/H2 composition at temperature 1000 °С on catalysts pre-deposited on silicon dioxide substrate. Before temperature treatment during the carbon nanotube synthesis most of the catalyst material agglomerates due to magnetic forces while during the nanotube growth disintegrates into the separate nanoparticles with narrow diameter distribution. The formed nanotube networks were characterized using AFM, scanning electron microscopy (SEM and Raman spectroscopy. We find that the nanotubes are mainly single-walled carbon nanotubes with high structural perfection up to 200 μm long with diameters from 1.3 to 1.7 nm consistent with catalyst nanoparticles diameter distribution and independent of its material.

  4. Effect of CTAB and SDS micelles on the excited state equilibria of some indole probes

    Science.gov (United States)

    Sharma, Neera; Jain, Sapan K.; Rastogi, Ramesh C.

    2007-11-01

    The absorption and fluorescence spectral characteristics of some biologically active indoles have been studied as a function of acidity and basicity (H_/pH/H o) in cationic (cetyltrimethylammonium bromide, CTAB), anionic (sodium dodecylsulphate, SDS) and aqueous phases at a given surfactant concentration. The prototropic equilibrium reactions of these probes have been studied in aqueous and micellar phases and apparent excited state acidity constant (pKa*) values are calculated. The probes show formation of different species on changing pH. Various species present in water, CTAB and SDS have been identified and the equilibrium constants have been determined by Fluorimetric Titration method. The fluorescence spectral data suggest the formation of oxonium ion through the excited state proton transfer reaction in highly acidic media and formation of photoproducts due to the base catalyzed auto-oxidative reaction in basic aqueous solutions. Variations in the apparent pKa* value have been observed in different media. The change in the apparent p Ka values depends upon the solubilising power of the micelles, as well as on the location of the protonating site in the molecule. The observation about increase in pKa* values in SDS and decrease in CTAB compared to pure water for various equilibria is consistent with the pseudophase ion-exchange (PIE) model.

  5. Molecular simulation study of water mobility in aerosol-OT reverse micelles.

    Science.gov (United States)

    Chowdhary, Janamejaya; Ladanyi, Branka M

    2011-06-16

    In this work, we present results from molecular dynamics simulations on the single-molecule relaxation of water within reverse micelles (RMs) of different sizes formed by the surfactant aerosol-OT (AOT, sodium bis(2-ethylhexyl)sulfosuccinate) in isooctane. Results are presented for RM water content w(0) = [H(2)O]/[AOT] in the range from 2.0 to 7.5. We show that translational diffusion of water within the RM can, to a good approximation, be decoupled from the translation of the RM through the isooctane solvent. Water translational mobility within the RM is restricted by the water pool dimensions, and thus, the water mean-squared displacements (MSDs) level off in time. Comparison with models of diffusion in confined geometries shows that a version of the Gaussian confinement model with a biexponential decay of correlations provides a good fit to the MSDs, while a model of free diffusion within a sphere agrees less well with simulation results. We find that the local diffusivity is considerably reduced in the interfacial region, especially as w(0) decreases. Molecular orientational relaxation is monitored by examining the behavior of OH and dipole vectors. For both vectors, orientational relaxation slows down close to the interface and as w(0) decreases. For the OH vector, reorientation is strongly affected by the presence of charged species at the RM interface and these effects are especially pronounced for water molecules hydrogen-bonded to surfactant sites that serve as hydrogen-bond acceptors. For the dipole vector, orientational relaxation near the interface slows down more than that for the OH vector due mainly to the influence of ion-dipole interactions with the sodium counterions. We investigate water OH and dipole reorientation mechanisms by studying the w(0) and interfacial shell dependence of orientational time correlations for different Legendre polynomial orders.

  6. Polymer micelles for delayed release of therapeutics from drug-releasing surfaces with nanotubular structures.

    Science.gov (United States)

    Sinn Aw, Moom; Addai-Mensah, Jonas; Losic, Dusan

    2012-08-01

    A new approach to engineer a local drug delivery system with delayed release using nanostructured surface with nanotube arrays is presented. TNT arrays electrochemically generated on a titanium surface are used as a model substrate. Polymer micelles as drug carriers encapsulated with drug are loaded at the bottom of the TNT structure and their delayed release is obtained by loading blank micelles (without drug) on the top. The delayed and time-controlled drug release is successfully demonstrated by controlling the ratio of blank and drug loaded-micelles. The concept is verified using four different polymer micelles (regular and inverted) loaded with water-insoluble (indomethacin) and water-soluble drugs (gentamicin).

  7. Rheological properties of novel viscoelastic micelle systems containing anionic-nonionic dimeric surfactant

    Institute of Scientific and Technical Information of China (English)

    方波; 曹丹红; 江体乾

    2008-01-01

    The viscoelastic micelle systems formed by novel anionic-nonionic dimeric surfactant and conventional cationic surfactant cetyltrimethylammonium(1631) were studied.The viscoelasticity,thixotropy,flow curves and constitutive equation for the novel viscoelastic micelle systems were investigated.The results show that the micelle systems possess viscoelasticity,thixotropy,and shear thinning property.Some micelle systems possess hysteresis loops showing both viscoelasticity and thixotropy.It is proved that the flow curves are characterized by the co-rotational Jeffreys constitutive equation correctly.

  8. ADVANCES IN MICROEMULSION PHASE ON SELF-ASSEMBLY AND MICELLE EXTRACTION WITH BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Chen Guo; Hao Wen; Huizhou Liu

    2005-01-01

    In this paper we review our work on self-assembly of the system, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers, which is a kind of macromolecular complex fluids. The control of self-assembly could be obtained by adding inorganic salts or aliphatic alcohols. By self-assembly of amphiphilic block copolymers, a microemulsion phase is formed, which could be applied in micelle extraction, such as hollow-fiber membrane micelle extraction, magnetic micelle extraction and immobilized micelle extraction.

  9. 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.

  10. Naturally derived micelles for rapid in vitro screening of potential cholesterol-lowering bioactives.

    Science.gov (United States)

    Kirana, Chandra; Rogers, Paul F; Bennett, Louise E; Abeywardena, Mahinda Y; Patten, Glen S

    2005-06-01

    A high plasma cholesterol level, especially low-density lipoprotein cholesterol, indicates increased risk of cardiovascular diseases. Plasma cholesterol levels are influenced by diet and cholesterol biosynthesis, uptake, and secretion. Cholesterol uptake involves solubilization into complex phospholipid spherical bodies termed micelles that facilitate the transport of lipids through the gut brush border membrane into enterocytes. In vitro assays reported to date to determine potential cholesterol-lowering effects of various compounds require artificial micelle preparations that are elaborate and time-consuming to prepare. The aims of this study were to compare the efficacy of artificially prepared micelles with naturally derived micelles from pig's bile and to test their ability to assess potential inhibitors of cholesterol uptake. The suitability of pig's bile-derived micelles was tested both at the level of the micelle and at cellular uptake using cultured Caco-2 cells. Known cholesterol uptake inhibitors at the micelle (green tea catechins) and at the Caco-2 cell (beta-lactoglobulin-derived peptide, IIAEK) were used as reference inhibitory compounds. It was concluded that pig's bile was a rapid, reproducible, convenient, and cost-effective source of micelles for cholesterol micelle solubility and cellular uptake assay systems and is suitable for screening purposes focused on identifying potential cholesterol-lowering agents.

  11. Doxorubicin-Loaded PEG-PCL-PEG Micelle Using Xenograft Model of Nude Mice: Effect of Multiple Administration of Micelle on the Suppression of Human Breast Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Cuong, Nguyen-Van [Department of Biomedical Engineering, Chung Yuan Christian University, 200, Chung Pei Rd., Chung Li, Taiwan (China); Department of Chemical Engineering, Ho Chi Minh City University of Industry, 12 Nguyen Van Bao St, Ho Chi Minh (Viet Nam); Jiang, Jian-Lin; Li, Yu-Lun [Department of Biomedical Engineering, Chung Yuan Christian University, 200, Chung Pei Rd., Chung Li, Taiwan (China); Chen, Jim-Ray [Department of Pathology, Chang Gung Memorial Hospital at Keelung, Taiwan and Chang Gung University, College of Medicine, Taoyuan, Taiwan (China); Jwo, Shyh-Chuan [Division of General Surgery, Chang Gung Memorial Hospital at Keelung, Taiwan and Chang Gung University, College of Medicine, Taoyuan, Taiwan (China); Hsieh, Ming-Fa, E-mail: mfhsieh@cycu.edu.tw [Department of Biomedical Engineering, Chung Yuan Christian University, 200, Chung Pei Rd., Chung Li, Taiwan (China)

    2010-12-28

    The triblock copolymer is composed of two identical hydrophilic segments Monomethoxy poly(ethylene glycol) (mPEG) and one hydrophobic segment poly(ε-caprolactone) (PCL); which is synthesized by coupling of mPEG-PCL-OH and mPEG-COOH in a mild condition using dicyclohexylcarbodiimide and 4-dimethylamino pyridine. The amphiphilic block copolymer can self-assemble into nanoscopic micelles to accommodate doxorubixin (DOX) in the hydrophobic core. The physicochemical properties and in vitro tests, including cytotoxicity of the micelles, have been characterized in our previous study. In this study, DOX was encapsulated into micelles with a drug loading content of 8.5%. Confocal microscopy indicated that DOX was internalized into the cytoplasm via endocystosis. A dose-finding scheme of the polymeric micelle (placebo) showed a safe dose of PEG-PCL-PEG micelles was 71.4 mg/kg in mice. Importantly, the circulation time of DOX-loaded micelles in the plasma significantly increased compared to that of free DOX in rats. A biodistribution study displayed that plasma extravasation of DOX in liver and spleen occurred in the first four hours. Lastly, the tumor growth of human breast cancer cells in nude mice was suppressed by multiple injections (5 mg/kg, three times daily on day 0, 7 and 14) of DOX-loaded micelles as compared to multiple administrations of free DOX.

  12. Doxorubicin-Loaded PEG-PCL-PEG Micelle Using Xenograft Model of Nude Mice: Effect of Multiple Administration of Micelle on the Suppression of Human Breast Cancer

    Directory of Open Access Journals (Sweden)

    Ming-Fa Hsieh

    2010-12-01

    Full Text Available The triblock copolymer is composed of two identical hydrophilic segments: Monomethoxy poly(ethylene glycol (mPEG and one hydrophobic segment poly(ε‑caprolactone (PCL; which is synthesized by coupling of mPEG-PCL-OH and mPEG‑COOH in a mild condition using dicyclohexylcarbodiimide and 4-dimethylamino pyridine. The amphiphilic block copolymer can self-assemble into nanoscopic micelles to accommodate doxorubixin (DOX in the hydrophobic core. The physicochemical properties and in vitro tests, including cytotoxicity of the micelles, have been characterized in our previous study. In this study, DOX was encapsulated into micelles with a drug loading content of 8.5%. Confocal microscopy indicated that DOX was internalized into the cytoplasm via endocystosis. A dose-finding scheme of the polymeric micelle (placebo showed a safe dose of PEG-PCL-PEG micelles was 71.4 mg/kg in mice. Importantly, the circulation time of DOX-loaded micelles in the plasma significantly increased compared to that of free DOX in rats. A biodistribution study displayed that plasma extravasation of DOX in liver and spleen occurred in the first four hours. Lastly, the tumor growth of human breast cancer cells in nude mice was suppressed by multiple injections (5 mg/kg, three times daily on day 0, 7 and 14 of DOX-loaded micelles as compared to multiple administrations of free DOX.

  13. Diclofenac sodium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002630.htm Diclofenac sodium overdose To use the sharing features on this page, please enable JavaScript. Diclofenac sodium is a prescription medicine used to relieve pain ...

  14. Naproxen sodium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002507.htm Naproxen sodium overdose To use the sharing features on this page, please enable JavaScript. Naproxen sodium is a nonsteroidal anti-inflammatory drug (NSAID) used ...

  15. Docusate Sodium and Pregnancy

    Science.gov (United States)

    ... live chat Live Help Fact Sheets Share Docusate Sodium Friday, 01 April 2016 In every pregnancy, a ... This sheet talks about whether exposure to docusate sodium may increase the risk for birth defects over ...

  16. Sodium carbonate poisoning

    Science.gov (United States)

    Sodium carbonate (known as washing soda or soda ash) is a chemical found in many household and ... products. This article focuses on poisoning due to sodium carbonate. This article is for information only. Do ...

  17. Sodium Ferric Gluconate Injection

    Science.gov (United States)

    Sodium ferric gluconate injection is used to treat iron-deficiency anemia (a lower than normal number of ... are also receiving the medication epoetin (Epogen, Procrit). Sodium ferric gluconate injection is in a class of ...

  18. Determining the critical micelle concentration of a novel lipid-lowering agent, disodium ascorbyl phytostanyl phosphate (FM-VP4), using a fluorescence depolarization procedure.

    Science.gov (United States)

    Wasan, Kishor M; Choo, Eugene; Sivak, Olena; Wallis, Simon; Letchford, Kevin; Burt, Helen M; Stewart, David J; Lukic, Tatjana

    2004-08-01

    The objective of this study was to determine the critical micelle concentration (CMC) of a novel water-soluble plant sterol derivative (FM-VP4) using a fluorescence depolarization method. The CMC was determined by 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence depolarization. Test solutions of various concentrations of sodium dodecylsulphate (SDS) as a positive control or FM-VP4 in water were spiked with 2 microL of 4 mM DPH in tetrahydrofuran (THF) and left overnight to equilibrate in a dark chamber. Fluorescence of each solution was measured at room temperature using a Perseptive Biosystems Cytofluor Series 4000 multi-well plate reader. Fluorescence intensity increases as DPH is incorporated into the hydrophobic core of micelles. Thus, the CMC is the value at which an abrupt increase in intensity is observed. These points were observed at 8 mM and 0.014 mM for SDS and FM-VP4, respectively. Sodium dodecylsulphate was used as a positive control and supports the validity of our results, as the literature values of SDS are reported to be between 8-8.3 mM. The CMC of FM-VP4 is reported to be 0.014 mM.

  19. Sodium sieving in children.

    NARCIS (Netherlands)

    Rusthoven, E.; Krediet, R.T.; Willems, H.L.; Monnens, L.A.H.; Schroder, C.H.

    2005-01-01

    Sodium sieving is a consequence of dissociation between the amount of water and sodium transported over the peritoneal membrane. This dissociation occurs in the presence of aquaporin-mediated water transport. Sieving of sodium can be used as a rough measure for aquaporin-mediated water transport. Ic

  20. Development, Characterization, and Evaluation of PSMA-Targeted Glycol Chitosan Micelles for Prostate Cancer Therapy

    Directory of Open Access Journals (Sweden)

    Jing Xu

    2014-01-01

    Full Text Available Prostate cancer-binding peptides- (PCP- modified polymeric micelles were prepared and used for the treatment of prostate-specific membrane antigen- (PSMA- expressing prostate cancer in a target-specific manner. Cholesterol-modified glycol chitosan (CHGC was synthesized. PCP-conjugated CHGC (PCP-CHGC micelles were fabricated and characterized. The degree of substitution was 5.2 PCP groups and 5.8 cholesterol groups per 100 sugar residues of glycol chitosan. The critical aggregation concentration (CAC of PCP-CHGC copolymer was 0.0254 mg/mL. Doxorubicin (DOX was chosen as a model antitumor drug. The DOX-loaded micelles were prepared by an o/w method. The mean diameter of DOX-loaded PCP-CHGC (DOX-PCP-CHGC micelles was 293 nm determined by dynamic light scattering (DLS. DOX released from drug-loaded micelles was in a biphasic manner. DOX-PCP-CHGC micelles exhibited higher cytotoxicity in vitro against PSMA-expressing LNCaP cells than DOX-loaded CHGC (DOX-CHGC micelles. Moreover, the cellular uptake of DOX-PCP-CHGC micelles determined by confocal laser scanning microscopy (CLSM and flow cytometry was higher than that of DOX-CHGC micelles in LNCaP cells. Importantly, DOX-PCP-CHGC micelles demonstrated stronger antitumor efficacy against LNCaP tumor xenograft models than doxorubicin hydrochloride and DOX-CHGC micelles. Taken together, this study provides a potential way in developing PSMA-targeted drug delivery system for prostate cancer therapy.

  1. Block copolymer micelles as nanocontainers for controlled release of proteins from biocompatible oil phases.

    Science.gov (United States)

    Miller, Andrew C; Bershteyn, Anna; Tan, Wuisiew; Hammond, Paula T; Cohen, Robert E; Irvine, Darrell J

    2009-04-13

    Biocompatible oils are used in a variety of medical applications ranging from vaccine adjuvants to vehicles for oral drug delivery. To enable such nonpolar organic phases to serve as reservoirs for delivery of hydrophilic compounds, we explored the ability of block copolymer micelles in organic solvents to sequester proteins for sustained release across an oil-water interface. Self-assembly of the block copolymer, poly(-caprolactone)-block-poly(2-vinyl pyridine) (PCL-b-P2VP), was investigated in toluene and oleic acid, a biocompatible naturally occurring fatty acid. Micelle formation in toluene was characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM) imaging of micelles cast onto silicon substrates. Cryogenic transmission electron microscopy confirmed a spherical morphology in oleic acid. Studies of homopolymer solubility implied that micelles in oleic acid consist of a P2VP corona and a PCL core, while P2VP formed the core of micelles assembled in toluene. The loading of two model proteins (ovalbumin (ova) and bovine serum albumin (BSA)) into micelles was demonstrated with loadings as high as 7.8% wt of protein per wt of P2VP in oleic acid. Characterization of block copolymer morphology in the two solvents after protein loading revealed spherical particles with similar size distributions to the as-assembled micelles. Release of ova from micelles in oleic acid was sustained for 12-30 h upon placing the oil phase in contact with an aqueous bath. Unique to the situation of micelle assembly in an oily phase, the data suggest protein is sequestered in the P2VP corona block of PCL-b-P2VP micelles in oleic acid. More conventionally, protein loading occurs in the P2VP core of micelles assembled in toluene.

  2. Sodium in feline nutrition.

    Science.gov (United States)

    Nguyen, P; Reynolds, B; Zentek, J; Paßlack, N; Leray, V

    2016-08-23

    High sodium levels in cat food have been controversial for a long time. Nonetheless, high sodium levels are used to enhance water intake and urine volume, with the main objective of reducing the risk of urolithiasis. This article is a review of current evidence of the putative risks and benefits of high dietary sodium levels. Its secondary aim is to report a possible safe upper limit (SUL) for sodium intake. The first part of the manuscript is dedicated to sodium physiology, with a focus on the mechanisms of sodium homeostasis. In this respect, there is only few information regarding possible interactions with other minerals. Next, the authors address how sodium intake affects sodium balance; knowledge of these effects is critical to establish recommendations for sodium feed content. The authors then review the consequences of changes in sodium intake on feline health, including urolithiasis, blood pressure changes, cardiovascular alterations and kidney disease. According to recent, long-term studies, there is no evidence of any deleterious effect of dietary sodium levels as high as 740 mg/MJ metabolizable energy, which can therefore be considered the SUL based on current knowledge.

  3. Unimolecular micelles and electrostatic nanoassemblies stemming from hyperbranched polyethyleneimine

    Energy Technology Data Exchange (ETDEWEB)

    Picco, A.; Azzaroni, O.; Ceolin, M. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplic, La Plata, BA (Argentina); Silbestri, G.F. [Universidad Nacional del Sur, Bahia Blanca Bueno (Argentina)

    2012-07-01

    Full text: Hyperbranched polyethyleneimine (HPEI) was used as a building block to construct different self-assembled soft nanomaterials. This was accomplished via covalent linkage of carboxylic acids (CA) of different chain lengths to terminal amino groups of HPEI, thus leading to the formation of reverse unimolecular micelles constituted of a hydrophilic core and a hydrophobic shell. On the other hand, acid base interactions in organic solvents between CAs and peripheral amino groups of HPEI also facilitated the formation of electrostatic assemblies with reverse micellar properties. In this work we describe the formation of both structures as well as their characterization using diverse techniques including SAXS, NMR, IR, and fluorescence spectroscopy, among others. Unimolecular micelles were synthesized through the reaction of HPEI (Mn= 10 KDa) and acyl chlorides with different chain lengths (C8, C10, C12, C14, C16, C18). Depending on the chain length, the solvent and the temperature, a broad variety of supra macromolecular assemblies can be observed by SAXS measurements, including structured aggregation, and gelation. Hyperbranched electrostatic assemblies were simply produced by mixing HPEI with selected carboxylic acids (C8, C10, C12, C14, C16, C18) in an appropriate solvent, which dissolves the CA, or both reactants, i.e. chloroform, toluene or THF. The formation of the assemblies was corroborated using FT-IR by monitoring the appearance of the carboxylate bands. SAXS experiments of electrostatically assembled micelles showed globular, core-shell structures, whose characteristics are similar, in many cases, to their covalent counterparts prepared using the same chain length CA shells. (author)

  4. Preparation and evaluation of novel mixed micelles as nanocarriers for intravenous delivery of propofol

    Science.gov (United States)

    Li, Xinru; Zhang, Yanhui; Fan, Yating; Zhou, Yanxia; Wang, Xiaoning; Fan, Chao; Liu, Yan; Zhang, Qiang

    2011-12-01

    Novel mixed polymeric micelles formed from biocompatible polymers, poly(ethylene glycol)-poly(lactide) (mPEG-PLA) and polyoxyethylene-660-12-hydroxy stearate (Solutol HS15), were fabricated and used as a nanocarrier for solubilizing poorly soluble anesthetic drug propofol. The solubilization of propofol by the mixed micelles was more efficient than those made of mPEG-PLA alone. Micelles with the optimized composition of mPEG-PLA/Solutol HS15/propofol = 10/1/5 by weight had particle size of about 101 nm with narrow distribution (polydispersity index of about 0.12). Stability analysis of the mixed micelles in bovine serum albumin (BSA) solution indicated that the diblock copolymer mPEG efficiently protected the BSA adsorption on the mixed micelles because the hydrophobic groups of the copolymer were efficiently screened by mPEG, and propofol-loaded mixed micelles were stable upon storage for at least 6 months. The content of free propofol in the aqueous phase for mixed micelles was lower by 74% than that for the commercial lipid emulsion. No significant differences in times to unconsciousness and recovery of righting reflex were observed between mixed micelles and commercial lipid formulation. The pharmacological effect may serve as pharmaceutical nanocarriers with improved solubilization capacity for poorly soluble drugs.

  5. Peptide-conjugated micelles as a targeting nanocarrier for gene delivery

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wen Jen, E-mail: wjlin@ntu.edu.tw; Chien, Wei Hsuan [National Taiwan University, School of Pharmacy, Graduate Institute of Pharmaceutical Sciences (China)

    2015-09-15

    The aim of this study was to develop peptide-conjugated micelles possessing epidermal growth factor receptor (EGFR) targeting ability for gene delivery. A sequence-modified dodecylpeptide, GE11(2R), with enhancing EGF receptor binding affinity, was applied in this study as a targeting ligand. The active targeting micelles were composed of poly(d,l-lactide-co-glycolide)-poly(ethylene glycol) (PLGA-PEG) copolymer conjugated with GE11(2R)-peptide. The particle sizes of peptide-free and peptide-conjugated micelles were 277.0 ± 5.1 and 308.7 ± 14.5 nm, respectively. The peptide-conjugated micelles demonstrated the cellular uptake significantly higher than peptide-free micelles in EGFR high-expressed MDA-MB-231 and MDA-MB-468 cells due to GE11(2R)-peptide specificity. Furthermore, the peptide-conjugated micelles were able to encapsulate plasmid DNA and expressed cellular transfection higher than peptide-free micelles in EGFR high-expressed cells. The EGFR-targeting delivery micelles enhanced DNA internalized into cells and achieved higher cellular transfection in EGFR high-expressed cells.

  6. Tuneable & degradable polymeric micelles for drug delivery: from synthesis to feasibility in vivo

    NARCIS (Netherlands)

    Rijcken, C.J.F.

    2007-01-01

    In recent years, colloidal systems (e.g. liposomes, nanoparticles and micelles) are increasingly applied as vehicles for controlled drug delivery purposes. Ideally, the encapsulation of hydrophobic drugs in a micellar core prolongs the systemic circulation and drug-loaded micelles selectively accumu

  7. Effect of Spacers on CMCs and Micelle-forming Enthalpies of Gemini Surfactants by Titration Microcalorimetry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The critical micelle concentrations (CMC) and the micelle-forming enthalpies (D Hmic) of gemini surfactants were first measured by the precise titration microcalorimetry. The results showed that D Hmic values are negative, and there is an exothermal minimum between s=4 and s=6. Furthermore, the CMCs of the surfactants are in good agreement with literature values.

  8. Comprehensive theory for star-like polymer micelles: combining classical nucleation and polymer brush theory

    NARCIS (Netherlands)

    Sprakel, J.H.B.; Leermakers, F.A.M.; Cohen Stuart, M.A.; Besseling, N.A.M.

    2008-01-01

    A comprehensive theory is proposed that combines classical nucleation and polymer brush theory to describe star-like polymer micelles. With a minimum of adjustable parameters, the model predicts properties such as critical micelle concentrations and micellar size distributions. The validity of the p

  9. Histological study on side effects and tumor targeting of a block copolymer micelle on rats.

    Science.gov (United States)

    Kawaguchi, Takanori; Honda, Takashi; Nishihara, Masamichi; Yamamoto, Tatsuhiro; Yokoyama, Masayuki

    2009-06-19

    Histological examinations were performed with polymeric micelle-injected rats for evaluations of possible toxicities of polymeric micelle carriers. Weight of major organs as well as body weight of rats was measured after multiple intravenous injections of polymeric micelles forming from poly(ethylene glycol)-b-poly(aspartate) block copolymer. No pathological toxic side effects were observed at two different doses, followed only by activation of the mononuclear phagocyte system (MPS) in the spleen, liver, lung, bone marrow, and lymph node. This finding confirms the absence of--or the very low level of--in vivo toxicity of the polymeric micelle carriers that were reported in previous animal experiments and clinical results. Then, immunohistochemical analyses with a biotinylated polymeric micelle confirmed specific accumulation of the micelle in the MPS. The immunohistochemical analyses also revealed, first, very rapid and specific accumulation of the micelle in the vasculatures of tumor capsule of rat ascites hepatoma AH109A, and second, the micelle's scanty infiltration into tumor parenchyma. This finding suggests a unique tumor-accumulation mechanism that is very different from simple EPR effect-based tumor targeting.

  10. Design of block-copolymer-based micelles for active and passive targeting

    NARCIS (Netherlands)

    Lebouille, Jérôme G.J.L.; Leermakers, Frans A.M.; Cohen Stuart, Martien A.; Tuinier, Remco

    2016-01-01

    A self-consistent field study is presented on the design of active and passive targeting block-copolymeric micelles. These micelles form in water by self-assembly of triblock copolymers with a hydrophilic middle block and two hydrophobic outer blocks. A minority amount of diblock copolymers with the

  11. Green synthetic, multifunctional hybrid micelles with shell embedded magnetic nanoparticles for theranostic applications.

    Science.gov (United States)

    Li, Yongyong; Ma, Junping; Zhu, Haiyan; Gao, Xiaolong; Dong, Haiqing; Shi, Donglu

    2013-08-14

    The objective of this study is to design and develop a green-synthetic, multifunctional hybrid micelles with shell embedded magnetic nanoparticles for theranostic applications. The hybrid micelles were engineered based on complex micelles self-assembled from amphiphilic block copolymers Pluronic F127 and peptide-amphiphile (PA) pal-AAAAHHHD. The reason to choose PA is due to its amphiphilic character and the coordination capability for Fe(3+) and Fe(2+). The PA incorporation allows the in situ growth of the magnetic iron oxide nanoparticles onto the complex micelles, to yield the nanostructures with shell embedded magnetic nanoparticles at an ambient condition without any organic solvents. The anticancer drug doxorubicin (DOX) can be efficiently loaded into the hybrid micelles. Interestingly, the magnetic nanoparticles anchored on the shell were found to significantly retard the DOX release behavior of the drug loaded hybrid micelles. It was proposed that a cross-linking effect of the shell by magnetic nanoparticles is a key to underlie the above intriguing phenomenon, which could enhance the stability and control the drug diffusion of the hybrid micelles. Importantly, in vitro and in vivo magnetic resonance imaging (MRI) revealed the potential of these hybrid micelles to be served as a T2-weighted MR imaging contrast enhancer for clinical diagnosis.

  12. Preparation and evaluation of novel mixed micelles as nanocarriers for intravenous delivery of propofol

    Directory of Open Access Journals (Sweden)

    Li Xinru

    2011-01-01

    Full Text Available Abstract Novel mixed polymeric micelles formed from biocompatible polymers, poly(ethylene glycol-poly(lactide (mPEG-PLA and polyoxyethylene-660-12-hydroxy stearate (Solutol HS15, were fabricated and used as a nanocarrier for solubilizing poorly soluble anesthetic drug propofol. The solubilization of propofol by the mixed micelles was more efficient than those made of mPEG-PLA alone. Micelles with the optimized composition of mPEG-PLA/Solutol HS15/propofol = 10/1/5 by weight had particle size of about 101 nm with narrow distribution (polydispersity index of about 0.12. Stability analysis of the mixed micelles in bovine serum albumin (BSA solution indicated that the diblock copolymer mPEG efficiently protected the BSA adsorption on the mixed micelles because the hydrophobic groups of the copolymer were efficiently screened by mPEG, and propofol-loaded mixed micelles were stable upon storage for at least 6 months. The content of free propofol in the aqueous phase for mixed micelles was lower by 74% than that for the commercial lipid emulsion. No significant differences in times to unconsciousness and recovery of righting reflex were observed between mixed micelles and commercial lipid formulation. The pharmacological effect may serve as pharmaceutical nanocarriers with improved solubilization capacity for poorly soluble drugs.

  13. The association of low-molecular-weight hydrophobic compounds with native casein micelles in bovine milk.

    Science.gov (United States)

    Cheema, M; Mohan, M S; Campagna, S R; Jurat-Fuentes, J L; Harte, F M

    2015-08-01

    The agreed biological function of the casein micelles in milk is to carry minerals (calcium, magnesium, and phosphorus) from mother to young along with amino acids for growth and development. Recently, native and modified casein micelles were used as encapsulating and delivery agents for various hydrophobic low-molecular-weight probes. The ability of modified casein micelles to bind certain probes may derive from the binding affinity of native casein micelles. Hence, a study with milk from single cows was conducted to further elucidate the association of hydrophobic molecules into native casein micelles and further understand their biological function. Hydrophobic and hydrophilic extraction followed by ultraperformance liquid chromatography-high resolution mass spectrometry analysis were performed over protein fractions obtained from size exclusion fractionation of raw skim milk. Hydrophobic compounds, including phosphatidylcholine, lyso-phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin, showed strong association exclusively to casein micelles as compared with whey proteins, whereas hydrophilic compounds did not display any preference for their association among milk proteins. Further analysis using liquid chromatography-tandem mass spectrometry detected 42 compounds associated solely with the casein-micelles fraction. Mass fragments in tandem mass spectrometry identified 4 of these compounds as phosphatidylcholine with fatty acid composition of 16:0/18:1, 14:0/16:0, 16:0/16:0, and 18:1/18:0. These results support that transporting low-molecular-weight hydrophobic molecules is also a biological function of the casein micelles in milk.

  14. The Role of Decorated SDS Micelles in Sub-CMC Protein Denaturation and Association

    DEFF Research Database (Denmark)

    Andersen, Kell; Oliveira, Cristiano Luis Pinto De; Larsen, K.L.;

    2009-01-01

    . Our data provide key structural insights into decorated micelle complexes with proteins, revealing a remarkable diversity in the different conformations they can stabilize. The data highlight that a minimum decorated micelle size, which may be a key driving force for intermolecular protein association...

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

    Science.gov (United States)

    Gou, MaLing; Shi, HuaShan; Guo, Gang; Men, Ke; Zhang, Juan; Zheng, Lan; Li, ZhiYong; Luo, Feng; Qian, ZhiYong; Zhao, Xia; Wei, YuQuan

    2011-03-01

    In an attempt to improve anticancer activity and reduce systemic toxicity of doxorubicin (Dox), we encapsulated Dox in monomethoxy poly(ethylene glycol)-poly(ɛ-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.

  16. Molecular dynamics simulations of helical antimicrobial peptides in SDS micelles: what do point mutations achieve?

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Kaznessis, Yiannis N

    2005-01-01

    We report long time scale simulations of the 18-residue helical antimicrobial peptide ovispirin-1 and its analogs novispirin-G10 and novispirin-T7 in SDS micelles. The SDS micelle serves as an economical and effective model for a cellular membrane. Ovispirin, which is initially placed along a mic...

  17. Separation of racemic mixture by ultrafiltration of enantioselective micelles. 2 (De) complexation kinetics

    NARCIS (Netherlands)

    Overdevest, P.E.M.; Schutyser, M.A.I.; Bruin, de T.J.M.; Riet, van 't K.; Keurentjes, J.T.F.; Padt, van der A.

    2001-01-01

    The application of enantioselective micelles in ultrafiltration systems can be an alternative route to meet the increasing demand for enantiopure products. We have studied the separation of D,L-phenylalanine (Phe) by cholesteryl-L-glutamate:CuII (CLG:CuII) anchored in nonionic micelles (intrinsic en

  18. Deoxycholic acid-grafted PEGylated chitosan micelles for the delivery of mitomycin C.

    Science.gov (United States)

    Zhang, Xiu-Rong; Shi, Nian-Qiu; Zhao, Yang; Zhu, He-Yun; Guan, Jiao; Jin, Ying

    2015-06-01

    Mitomycin C (MTC) was incorporated to a micelle system preparing from a polymer named deoxycholic acid chitosan-grafted poly(ethylene glycol) methyl ether (mPEG-CS-DA). mPEG-CS-DA was synthesized and characterized by (1)H nuclear magnetic resonance ((1)H-NMR) and Fourier transform infrared spectroscopy. mPEG-CS-DA formed a core-shell micellar structure with a critical micelle concentration of 6.57 µg/mL. The mPEG-CS-DA micelles were spherical with a hydrodynamic diameter of about 231 nm. After poly(ethylene glycol)ylation of deoxycholic acid chitosan (CS-DA), the encapsulation efficiency and drug loading efficiency increased from 50.62% to 56.42% and from 20.51% to 24.13%, respectively. The mPEG-CS-DA micelles possessed a higher drug release rate than the CS-DA micelles. For pharmacokinetics, the area under the curve (AUC) of the mPEG-CS-DA micelles was 1.5 times higher than that of MTC injection, and these micelles can enhance the bioavailability of MTC. mPEG-CS-DA micelles reduced the distribution of MTC in almost all normal tissues and had the potential to improve the kidney toxicity caused by MTC injection.

  19. 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.

  20. Delivery of the photosensitizer Pc 4 in PEG-PCL micelles for in vitro PDT studies.

    Science.gov (United States)

    Master, Alyssa M; Rodriguez, Myriam E; Kenney, Malcolm E; Oleinick, Nancy L; Gupta, Anirban Sen

    2010-05-01

    The silicon phthalocyanine Pc 4 is a second-generation photosensitizer that has several properties superior to other photosensitizers currently approved by the FDA, and it has shown significant promise for photodynamic therapy (PDT) in several cancer cells in vitro and model tumor systems in vivo. However, because of the high hydrophobicity of Pc 4, its formulation for in vivo delivery and favorable biodistribution become challenging. To this end, we are studying encapsulation and delivery of Pc 4 in block copolymer micelles. Here, we report the development of biocompatible PEG-PCL micelle nanoparticles, encapsulation of Pc 4 within the micelle core by hydrophobic association with the PCL block, and in vitro PDT studies of the micelle-formulated Pc 4 in MCF-7c3 human breast cancer cells. Our studies demonstrate efficient encapsulation of Pc 4 in the micelles, intracellular uptake of the micelle-formulated Pc 4 in cells, and significant cytotoxic effect of the formulation upon photoirradiation. Quantitative estimation of the extent of Pc 4 loading in the micelles and the photocytotoxicity of the micelle-incorporated Pc 4 demonstrate the promise of our approach to develop a biocompatible nanomedicine platform for tumor-targeted delivery of Pc 4 for site-selective PDT.

  1. Self-consistent-field calculations of proteinlike incorporations in polyelectrolyte complex micelles

    NARCIS (Netherlands)

    Lindhoud, S.; Cohen Stuart, M.A.; Norde, W.; Leermakers, F.A.M.

    2009-01-01

    Self-consistent field theory is applied to model the structure and stability of polyelectrolyte complex micelles with incorporated protein (molten globule) molecules in the core. The electrostatic interactions that drive the micelle formation are mimicked by nearest-neighbor interactions using

  2. Shaping and patterning gold nanoparticles via micelle templated photochemistry

    Science.gov (United States)

    Kundrat, F.; Baffou, G.; Polleux, J.

    2015-09-01

    Shaping and positioning noble metal nanostructures are essential processes that still require laborious and sophisticated techniques to fabricate functional plasmonic interfaces. The present study reports a simple photochemical approach compatible with micellar nanolithography and photolithography that enables the growth, arrangement and shaping of gold nanoparticles with tuneable plasmonic resonances on glass substrates. Ultraviolet illumination of surfaces coated with gold-loaded micelles leads to the formation of gold nanoparticles with micro/nanometric spatial resolution without requiring any photosensitizers or photoresists. Depending on the extra-micellar chemical environment and the illumination wavelength, block copolymer micelles act as reactive and light-responsive templates, which enable to grow gold deformed nanoparticles (potatoids) and nanorings. Optical characterization reveals that arrays of individual potatoids and rings feature a localized plasmon resonance around 600 and 800 nm, respectively, enhanced photothermal properties and high temperature sustainability, making them ideal platforms for future developments in nanochemistry and biomolecular manipulation controlled by near-infrared-induced heat.Shaping and positioning noble metal nanostructures are essential processes that still require laborious and sophisticated techniques to fabricate functional plasmonic interfaces. The present study reports a simple photochemical approach compatible with micellar nanolithography and photolithography that enables the growth, arrangement and shaping of gold nanoparticles with tuneable plasmonic resonances on glass substrates. Ultraviolet illumination of surfaces coated with gold-loaded micelles leads to the formation of gold nanoparticles with micro/nanometric spatial resolution without requiring any photosensitizers or photoresists. Depending on the extra-micellar chemical environment and the illumination wavelength, block copolymer micelles act as

  3. Mechano-responsive hydrogels crosslinked by reactive block copolymer micelles

    Science.gov (United States)

    Xiao, Longxi

    Hydrogels are crosslinked polymeric networks that can swell in water without dissolution. Owing to their structural similarity to the native extracelluar matrices, hydrogels have been widely used in biomedical applications. Synthetic hydrogels have been designed to respond to various stimuli, but mechanical signals have not incorporated into hydrogel matrices. Because most tissues in the body are subjected to various types of mechanical forces, and cells within these tissues have sophisticated mechano-transduction machinery, this thesis is focused on developing hydrogel materials with built-in mechano-sensing mechanisms for use as tissue engineering scaffolds or drug release devices. Self-assembled block copolymer micelles (BCMs) with reactive handles were employed as the nanoscopic crosslinkers for the construction of covalently crosslinked networks. BCMs were assembled from amphiphilic diblock copolymers of poly(n-butyl acrylate) and poly(acrylic acid) partially modified with acrylate. Radical polymerization of acrylamide in the presence of micellar crosslinkers gave rise to elastomeric hydrogels whose mechanical properties can be tuned by varying the BCM composition and concentration. TEM imaging revealed that the covalently integrated BCMs underwent strain-dependent reversible deformation. A model hydrophobic drug, pyrene, loaded into the core of BCMs prior to the hydrogel formation, was dynamically released in response to externally applied mechanical forces, through force-induced reversible micelle deformation and the penetration of water molecules into the micelle core. The mechano-responsive hydrogel has been studied for tissue repair and regeneration purposes. Glycidyl methacrylate (GMA)-modified hyaluronic acid (HA) was photochemically crosslinked in the presence of dexamethasone (DEX)-loaded crosslinkable BCMs. The resultant HA gels (HAxBCM) contain covalently integrated micellar compartments with DEX being sequestered in the hydrophobic core. Compared

  4. A comparison study between sodium dodecyl sulfate and sodium dodecyl sulfonate with respect to the thermodynamic properties, micellization, and interaction with poly(ethylene glycol) in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Rahmat, E-mail: rsadeghi@uok.ac.ir [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Shahabi, Somayyeh [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

    2011-09-15

    Graphical abstract: Apparent molar volume against molality: o, {center_dot}, and {Delta}, respectively in water, (1 and 4) wt% PEG solution at 293.15 K; x, {Delta}, and lozenge, respectively in water, (1 and 4) wt% PEG solution at 313.15 K. Research Highlights: > C{sub 12}H{sub 25}SO{sub 3}Na(SDSn) was seen to interact with PEG more weakly than C{sub 12}H{sub 25}SO{sub 4}Na(SDS). > The constraints on molecular mobility of SDS micelles are larger than those of SDSn. > Entropy change on micellization for SDSn is larger than those for SDS. > Micelle formation of SDS is less endothermic and more spontaneous than that of SDSn. > Micelles of SDS have smaller aggregation number than that of SDSn. - Abstract: The density, sound velocity, and conductivity measurements were performed on aqueous solutions of sodium dodecyl sulfate (C{sub 12}H{sub 25}SO{sub 4}Na) or sodium dodecyl sulfonate (C{sub 12}H{sub 25}SO{sub 3}Na) in the absence and presence of poly(ethylene glycol) (PEG) at different temperatures. Changes in the apparent molar volumes and isentropic compressibilities upon micellization were derived using a pseudophase-transition approach and the infinite dilution apparent molar properties of the monomer and micellar form of C{sub 12}H{sub 25}SO{sub 4}Na and C{sub 12}H{sub 25}SO{sub 3}Na were determined. Variations of the critical micelle concentrations (CMCs) of both surfactants in the solutions investigated with temperature were obtained from which thermodynamic parameters of micellization were estimated. It was found that at low temperature the micelle formation process is endothermic and therefore, this process must be entropically driven. However, upon increasing the temperature, the enthalpic factor becomes more significant and, at temperatures higher than 303.15 K the micellization is enthalpy driven. The interactions between C{sub 12}H{sub 25}SO{sub 4}Na/C{sub 12}H{sub 25}SO{sub 3}Na and PEG were studied and it was found that sodium alkyl sulfonates were seen

  5. Factors influencing casein micelle size in milk of individual cows: Genetic variants and glycosylation of k-casein

    NARCIS (Netherlands)

    Bijl, E.; Vries, de R.F.M.; Valenberg, van H.J.F.; Huppertz, T.; Hooijdonk, van A.C.M.

    2014-01-01

    The average casein micelle size varies widely between milk samples of individual cows. The factors that cause this variation in size are not known but could provide more insight into casein micelle structure and into the physiology of casein micelle formation. The objective of this research was ther

  6. Lung surfactant protein A (SP-A) interactions with model lung surfactant lipids and an SP-B fragment.

    Science.gov (United States)

    Sarker, Muzaddid; Jackman, Donna; Booth, Valerie

    2011-06-07

    Surfactant protein A (SP-A) is the most abundant protein component of lung surfactant, a complex mixture of proteins and lipids. SP-A performs host defense activities and modulates the biophysical properties of surfactant in concerted action with surfactant protein B (SP-B). Current models of lung surfactant mechanism generally assume SP-A functions in its octadecameric form. However, one of the findings of this study is that when SP-A is bound to detergent and lipid micelles that mimic lung surfactant phospholipids, it exists predominantly as smaller oligomers, in sharp contrast to the much larger forms observed when alone in water. These investigations were carried out in sodium dodecyl sulfate (SDS), dodecylphosphocholine (DPC), lysomyristoylphosphatidylcholine (LMPC), lysomyristoylphosphatidylglycerol (LMPG), and mixed LMPC + LMPG micelles, using solution and diffusion nuclear magnetic resonance (NMR) spectroscopy. We have also probed SP-A's interaction with Mini-B, a biologically active synthetic fragment of SP-B, in the presence of micelles. Despite variations in Mini-B's own interactions with micelles of different compositions, SP-A is found to interact with Mini-B in all micelle systems and perhaps to undergo a further structural rearrangement upon interacting with Mini-B. The degree of SP-A-Mini-B interaction appears to be dependent on the type of lipid headgroup and is likely mediated through the micelles, rather than direct binding.

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

    Science.gov (United States)

    Zhou, Weisai; Li, Caibin; Wang, Zhiyu; Zhang, Wenli; Liu, Jianping

    2016-09-01

    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.

  8. Dissipative Particle Dynamics Study on Aggregation of MPEG- PAE-PLA Block Polymer Micelles Loading Doxorubicine

    Institute of Scientific and Technical Information of China (English)

    杨楚芬; 孙尧; 章莉娟; 朱国典; 张灿阳; 钱宇

    2012-01-01

    To guide the molecular design of the pH-sensitive triblock amphiphilic polymer MPEG-PAE-PLA and the for- mula design of its doxorubicine (DOX)-loaded micelles, dissipative particle dynamics (DPD) simulations are em- ployed to investigate the aggregation behaviors of the DOX-loaded micelles. The simulation results showed that the aggregate morphologies of micelles and DOX distribution are influenced by degree of polymerization of blocks, and the proposed structure of polymer is MPEG44-PAE3-PLA4. With different contents of polymer or DOX, differ- ent aggregate morphologies of the micelles, like microsphere, spindle/column, reticulation or lamella are observed. To prepare the micro-spherical DOX-loaded micelles, the polymer content is proposed as 10%--15%, and the DOX content less than 10%.

  9. Effective repair of traumatically injured spinal cord by nanoscale block copolymer micelles

    Science.gov (United States)

    Shi, Yunzhou; Kim, Sungwon; Huff, Terry B.; Borgens, Richard B.; Park, Kinam; Shi, Riyi; Cheng, Ji-Xin

    2010-01-01

    Spinal cord injury results in immediate disruption of neuronal membranes, followed by extensive secondary neurodegenerative processes. A key approach for repairing injured spinal cord is to seal the damaged membranes at an early stage. Here, we show that axonal membranes injured by compression can be effectively repaired using self-assembled monomethoxy poly(ethylene glycol)-poly(D,L-lactic acid) di-block copolymer micelles. Injured spinal tissue incubated with micelles (60 nm diameter) showed rapid restoration of compound action potential and reduced calcium influx into axons for micelle concentrations much lower than the concentrations of polyethylene glycol, a known sealing agent for early-stage spinal cord injury. Intravenously injected micelles effectively recovered locomotor function and reduced the volume and inflammatory response of the lesion in injured rats, without any adverse effects. Our results show that copolymer micelles can interrupt the spread of primary spinal cord injury damage with minimal toxicity.

  10. The influence of bile acids on the oral bioavailability of vitamin K encapsulated in polymeric micelles.

    Science.gov (United States)

    van Hasselt, P M; Janssens, G E P J; Slot, T K; van der Ham, M; Minderhoud, T C; Talelli, M; Akkermans, L M; Rijcken, C J F; van Nostrum, C F

    2009-01-19

    The purpose of this study was to assess the ability of polymeric micelles to enable gastrointestinal absorption of the extremely hydrophobic compound vitamin K, by comparison of its absorption in bile duct ligated and sham operated rats. Hereto, vitamin K was encapsulated in micelles composed of mPEG(5000)-b-p(HPMAm-lac(2)), a thermosensitive block copolymer. Vitamin K plasma levels rose significantly upon gastric administration of 1 mg vitamin K encapsulated in polymeric micelles in sham operated rats, but not after bile duct ligation (AUC 4543 and 1.64 ng/mL/h respectively, pvitamin K from polymeric micelles is mediated by free bile and that uptake of intact micelles through pinocytosis is insignificant.

  11. Tumor homing indocyanine green encapsulated micelles for near infrared and photoacoustic imaging of tumors.

    Science.gov (United States)

    Uthaman, Saji; Bom, Joon-suk; Kim, Hyeon Sik; John, Johnson V; Bom, Hee-Seung; Kim, Seon-Jong; Min, Jung-Joon; Kim, Il; Park, In-Kyu

    2016-05-01

    Photoacoustic imaging (PAI) is an emerging analytical modality that is under intense preclinical development for the early diagnosis of various medical conditions, including cancer. However, the lack of specific tumor targeting by various contrast agents used in PAI obstructs its clinical applications. In this study, we developed indocyanine green (ICG)-encapsulated micelles specific for the CD 44 receptor and used in near infrared and photoacoustic imaging of tumors. ICG was hydrophobically modified prior to loading into hyaluronic acid (HA)-based micelles utilized for CD 44 based-targeting. We investigated the physicochemical characteristics of prepared HA only and ICG-encapsulated HA micelles (HA-ICG micelles). After intravenous injection of tumor-bearing mice, the bio-distribution and in vivo photoacoustic images of ICG-encapsulated HA micelles accumulating in tumors were also investigated. Our study further encourages the application of this HA-ICG-based nano-platform as a tumor-specific contrast agent for PAI.

  12. Tuning intermicellar potential of Triton X-100– anthranilic acid mixed micelles

    Indian Academy of Sciences (India)

    Gunjan Verma; V K Aswal; S K Kulshreshtha; C Manohar; P A Hassan; Eric W Kaler

    2008-11-01

    Structural parameters of micelles formed by Triton X-100 in the presence of solubilized anthranilic acid at different pH values was investigated using light scattering and small angle neutron scattering. Analysis of the SANS data indicate that micelles are oblate ellipsoidal in nature with little variation in the dimensions, in the investigated pH range (from 0.5 to 6.0). The interaction potential of the micelles shows a minimum closer to the isoelectric point of anthranilic acid. A similar variation is observed in the cloud point of the micelles with pH. The observed variation in the interaction potential with pH of the micellar solution can be explained in terms of the reversal of charge on anthranilic acid due to shift in the acid–base equilibrium. The variation in interaction potential and cloud point with pH is modelled using Coulombic repulsion of charged molecules at the micelle interface.

  13. Effective repair of traumatically injured spinal cord by nanoscale block copolymer micelles.

    Science.gov (United States)

    Shi, Yunzhou; Kim, Sungwon; Huff, Terry B; Borgens, Richard B; Park, Kinam; Shi, Riyi; Cheng, Ji-Xin

    2010-01-01

    Spinal cord injury results in immediate disruption of neuronal membranes, followed by extensive secondary neurodegenerative processes. A key approach for repairing injured spinal cord is to seal the damaged membranes at an early stage. Here, we show that axonal membranes injured by compression can be effectively repaired using self-assembled monomethoxy poly(ethylene glycol)-poly(d,l-lactic acid) di-block copolymer micelles. Injured spinal tissue incubated with micelles (60 nm diameter) showed rapid restoration of compound action potential and reduced calcium influx into axons for micelle concentrations much lower than the concentrations of polyethylene glycol, a known sealing agent for early-stage spinal cord injury. Intravenously injected micelles effectively recovered locomotor function and reduced the volume and inflammatory response of the lesion in injured rats, without any adverse effects. Our results show that copolymer micelles can interrupt the spread of primary spinal cord injury damage with minimal toxicity.

  14. Crafting threads of diblock copolymer micelles via flow-enabled self-assembly.

    Science.gov (United States)

    Li, Bo; Han, Wei; Jiang, Beibei; Lin, Zhiqun

    2014-03-25

    Hierarchically assembled amphiphilic diblock copolymer micelles were exquisitely crafted over large areas by capitalizing on two concurrent self-assembling processes at different length scales, namely, the periodic threads composed of a monolayer or a bilayer of diblock copolymer micelles precisely positioned by flow-enabled self-assembly (FESA) on the microscopic scale and the self-assembly of amphiphilic diblock copolymer micelles into ordered arrays within an individual thread on the nanometer scale. A minimum spacing between two adjacent threads λmin was observed. A model was proposed to rationalize the relationship between the thread width and λmin. Such FESA of diblock copolymer micelles is remarkably controllable and easy to implement. It opens up possibilities for lithography-free positioning and patterning of diblock copolymer micelles for various applications in template fabrication of periodic inorganic nanostructures, nanoelectronics, optoelectronics, magnetic devices, and biotechnology.

  15. Synthesis of Cross-Linked Polymeric Micelle pH Nanosensors

    DEFF Research Database (Denmark)

    Ek, Pramod Kumar; Jølck, Rasmus Irming; Andresen, Thomas Lars

    2015-01-01

    at the micelle shell using CuAAC results in a stabilized micelle pH nanosensor. Compared to the postmicelle modification strategy, the mixed-micellization approach increases the control of the overall composition of the nanosensors.Both approaches provide stable nanosensors with similar pKa profiles and thereby......The design flexibility that polymeric micelles offer in the fabrication of optical nanosensors for ratiometric pH measurements is investigated. pH nanosensors based on polymeric micelles are synthesized either by a mixed-micellization approach or by a postmicelle modification strategy. In the mixed......-micellization approach, self-assembly of functionalized unimers followed by shell cross-linking by copper-catalyzed azide-alkyne cycloaddition (CuAAC) results in stabilized cRGD-functionalized micelle pH nanosensors. In the postmicelle modification strategy, simultaneous cross-linking and fluorophore conjugation...

  16. Renal sodium handling and sodium sensitivity

    Directory of Open Access Journals (Sweden)

    Alissa A. Frame

    2017-06-01

    Full Text Available The pathophysiology of hypertension, which affects over 1 billion individuals worldwide, involves the integration of the actions of multiple organ systems, including the kidney. The kidney, which governs sodium excretion via several mechanisms including pressure natriuresis and the actions of renal sodium transporters, is central to long term blood pressure regulation and the salt sensitivity of blood pressure. The impact of renal sodium handling and the salt sensitivity of blood pressure in health and hypertension is a critical public health issue owing to the excess of dietary salt consumed globally and the significant percentage of the global population exhibiting salt sensitivity. This review highlights recent advances that have provided new insight into the renal handling of sodium and the salt sensitivity of blood pressure, with a focus on genetic, inflammatory, dietary, sympathetic nervous system and oxidative stress mechanisms that influence renal sodium excretion. Increased understanding of the multiple integrated mechanisms that regulate the renal handling of sodium and the salt sensitivity of blood pressure has the potential to identify novel therapeutic targets and refine dietary guidelines designed to treat and prevent hypertension.

  17. Preparation of stable spherical micelles with rigid backbones based on polyaryletherketone copolymers containing lateral pyridyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuling; Liu, Lingzhi; Guo, Yunliang; Jiang, Zhenhua; Wang, Guibin, E-mail: wgb@jlu.edu.cn

    2013-07-15

    A new bisphenol monomer, 3-(3,4-dihydroxyphenylimine) pyridine (PYPH), was synthesized via a deoxidization reaction of an amine. A series of novel polyaryletherketone copolymers containing lateral pyridyl groups (PY-PAEKs) based on PYPH, 2,2-di(4-hydroxyphenyl)propane and 4,4′-difluorobenzophenone were prepared by nucleophilic aromatic substitution polycondensation reactions. Furthermore, spherical micelles with rigid PY-PAEKs as the inner cores and flexible polyacrylic acid (PAA) as the outer shells were obtained in a selective solvent (H{sub 2}O) successfully. The formation of the spherical micelles was confirmed by scanning electron and transmission electron microscopy as well as by surface tension measurements. The formation and size of the spherical micelles depended on the weight ratio of PAA/PY-PAEK, the concentration and pH value of the mixed solution containing the PY-PAEK and PAA, and the number of pyridyl groups in the PY-PAEK. The structure of the spherical micelles could be stabilized by a cross-linking reaction between the pyridyl groups of the PY-PAEKs and 1,4-dibromobutane. The diameter of the spherical micelles decreased because of the removal of the PAA shell from the PY-PAEK core after the cross-linking reaction. The resulting stable spherical micelles with rigid backbones did not dissolve in a number of polar solvents and remained unaffected by changes in the pH values. - Graphical abstract: Display Omitted - Highlights: • Polyaryletherketone copolymers containing lateral pyridyl groups were synthesized. • Spherical micelles were prepared using these copolymers and polyacrylic acid. • The copolymers and polyacrylic acid formed the core and the shell of the micelles, respectively. • The obtained micelles were stabilized by a cross-linking reaction. • The cross-linked micelles had rigid backbones, independent of solvents and pH values.

  18. Curcumin-loaded biodegradable polymeric micelles for colon cancer therapy in vitro and in vivo

    Science.gov (United States)

    Gou, Maling; Men, Ke; Shi, Huashan; Xiang, Mingli; Zhang, Juan; Song, Jia; Long, Jianlin; Wan, Yang; Luo, Feng; Zhao, Xia; Qian, Zhiyong

    2011-04-01

    Curcumin is an effective and safe anticancer agent, but its hydrophobicity inhibits its clinical application. Nanotechnology provides an effective method to improve the water solubility of hydrophobic drug. In this work, curcumin was encapsulated into monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelles through a single-step nano-precipitation method, creating curcumin-loaded MPEG-PCL (Cur/MPEG-PCL) micelles. These Cur/MPEG-PCL micelles were monodisperse (PDI = 0.097 +/- 0.011) with a mean particle size of 27.3 +/- 1.3 nm, good re-solubility after freeze-drying, an encapsulation efficiency of 99.16 +/- 1.02%, and drug loading of 12.95 +/- 0.15%. Moreover, these micelles were prepared by a simple and reproducible procedure, making them potentially suitable for scale-up. Curcumin was molecularly dispersed in the PCL core of MPEG-PCL micelles, and could be slow-released in vitro. Encapsulation of curcumin in MPEG-PCL micelles improved the t1/2 and AUC of curcuminin vivo. As well as free curcumin, Cur/MPEG-PCL micelles efficiently inhibited the angiogenesis on transgenic zebrafish model. In an alginate-encapsulated cancer cell assay, intravenous application of Cur/MPEG-PCL micelles more efficiently inhibited the tumor cell-induced angiogenesisin vivo than that of free curcumin. MPEG-PCL micelle-encapsulated curcumin maintained the cytotoxicity of curcumin on C-26 colon carcinoma cellsin vitro. Intravenous application of Cur/MPEG-PCL micelle (25 mg kg-1curcumin) inhibited the growth of subcutaneous C-26 colon carcinoma in vivo (p colon carcinoma through inhibiting angiogenesis and directly killing cancer cells.

  19. PEG-OCL micelles for quercetin solubilization and inhibition of cancer cell growth.

    Science.gov (United States)

    Khonkarn, Ruttiros; Mankhetkorn, Samlee; Hennink, Wim E; Okonogi, Siriporn

    2011-10-01

    In this study, quercetin (QCT), a flavonoid with high anticancer potential, was loaded into polymeric micelles of PEG-OCL (poly(ethylene glycol)-b-oligo(ε-caprolactone)) with naphthyl or benzyl end groups in order to increase its aqueous solubility. The cytostatic activity of the QCT-loaded micelles toward different human cancer cell lines and normal cells was investigated. The results showed that the solubility of QCT entrapped in mPEG750-b-OCL micelles was substantially increased up to 1 mg/ml, which is approximately 110 times higher than that of its solubility in water (9 μg/ml). The average particle size of QCT-loaded micelles ranged from 14 to 19 nm. The QCT loading capacity of the polymeric micelles with naphthyl groups was higher than that with benzyl groups (10% and 6%, respectively). QCT-loaded, benzyl- and naphthyl-modified micelles effectively inhibited the growth of both sensitive and resistance cancer cells (human erythromyelogenous leukemia cells (K562) and small lung carcinoma cells (GLC4)). However, the benzyl-modified micelles have a good cytocompatibility (in the concentration range investigated (up to 100 μg/ml), they are well tolerated by living cells), whereas their naphthyl counterparts showed some cytotoxicity at higher concentrations (60-100 μg/ml). Flow cytometry demonstrated that the mechanism underlying the growth inhibitory effect of QCT in its free form was inducing cell cycle arrest at the G2/M phase. Benzyl-modified micelles loaded with QCT also exhibited this cycle arresting the effect of cancer cells. In conclusion, this paper shows the enhancement of solubility and cell cycle arrest of QCT loaded into micelles composed of mPEG750-b-OCL modified with benzyl end groups. These micelles are therefore considered to be an attractive vehicle for the (targeted) delivery of QCT to tumors.

  20. Cerebrospinal fluid sodium rhythms

    Directory of Open Access Journals (Sweden)

    Johnson Benjamin

    2010-01-01

    Full Text Available Abstract Background Cerebrospinal fluid (CSF sodium levels have been reported to rise during episodic migraine. Since migraine frequently starts in early morning or late afternoon, we hypothesized that natural sodium chronobiology may predispose susceptible persons when extracellular CSF sodium increases. Since no mammalian brain sodium rhythms are known, we designed a study of healthy humans to test if cation rhythms exist in CSF. Methods Lumbar CSF was collected every ten minutes at 0.1 mL/min for 24 h from six healthy participants. CSF sodium and potassium concentrations were measured by ion chromatography, total protein by fluorescent spectrometry, and osmolarity by freezing point depression. We analyzed cation and protein distributions over the 24 h period and spectral and permutation tests to identify significant rhythms. We applied the False Discovery Rate method to adjust significance levels for multiple tests and Spearman correlations to compare sodium fluctuations with potassium, protein, and osmolarity. Results The distribution of sodium varied much more than potassium, and there were statistically significant rhythms at 12 and 1.65 h periods. Curve fitting to the average time course of the mean sodium of all six subjects revealed the lowest sodium levels at 03.20 h and highest at 08.00 h, a second nadir at 09.50 h and a second peak at 18.10 h. Sodium levels were not correlated with potassium or protein concentration, or with osmolarity. Conclusion These CSF rhythms are the first reports of sodium chronobiology in the human nervous system. The results are consistent with our hypothesis that rising levels of extracellular sodium may contribute to the timing of migraine onset. The physiological importance of sodium in the nervous system suggests that these rhythms may have additional repercussions on ultradian functions.

  1. Vesicle formation and stability in the surfactant sodium 4-(1'-heptylnonyl) benzenesulfonate

    Energy Technology Data Exchange (ETDEWEB)

    Franses, E.I.; Talmon, Y.; Scriven, L.E.; Davis, H.T.; Miller, W.G.

    1982-04-01

    Surfactants composed of a hydrophilic moiety covalently attached to the end of a hydrocarbon chain (e.g., sodium dodecyl sulfate), spontaneously form micelles, equilibrium aggregates, in solution if the surfactant concentration exceeds a critical value called the CMC. Naturally occurring double-tail surfactants (e.g., phospholipids) are not known to form micelles. Over a considerable range in surfactant concentration, 2 phases coexist in equilibrium: a hydrated, multilamellar (smectic) surfactant phase and an aqueous phase saturated with surfactant. In this report the preparation of vesicles, their direct, unstained visualization by electron microscopy, and investigation of their stability and structure by turbidimetry, conductimetry, light microscopy, densitometry, scanning calorimetry, and nuclear magnetic resonance spectroscopy are discussed. Dispersed liquid crystal was studied by the same means. For comparison, parallel studies on bovine lecithin are presented. From the results, it is concluded that these vesicles may be stable for many months, but eventually revert to multilamellar liquid crystals.

  2. Molecular exchange in block copolymer micelles: when corona chains overlap

    Science.gov (United States)

    Lu, Jie; Lodge, Timothy; Bates, Frank; Choi, Soohyung

    2013-03-01

    The chain exchange kinetics of poly(styrene-b-ethylenepropylene) (PS-PEP) diblock copolymer micelles in squalane (C30H62) was investigated using time-resolved small angle neutron scattering (TR-SANS). The solvent is a mixture of h-squalane and d-squalane that contrast-matches a mixed 50/50 h/d PS micelle core. As isotope labeled chains exchange, the core contrast decreases, leading to a reduction in scattering intensity. This strategy therefore allows direct probing of the chain exchange rate. Separate copolymer micellar solutions containing either deuterium labeled (dPS) or normal (hPS) poly(styrene) core blocks were prepared and mixed at room temperature, below the core glass transition temperature. The samples were heated to several temperatures (around 100 °C) and monitored by TR-SANS every 5 min. As polymer concentration was increased from 1% to 15% by volume, we observed a significant slowing down of chain exchange rate. Similar retarded kinetics was found when part of the solvent in the 1% solution was replaced by homopolymer PEP (comparable size as corona block). Furthermore, if all the solvent is replaced with PEP, no exchange was detected for up to 3hr at 200 °C. These results will be discussed in terms of a molecular model for chain exchange Infineum, Iprime, NIST, ORNL

  3. Modulation of ROS production in human leukocytes by ganglioside micelles

    Directory of Open Access Journals (Sweden)

    M. Gavella

    2010-10-01

    Full Text Available Recent studies have reported that exogenous gangliosides, the sialic acid-containing glycosphingolipids, are able to modulate many cellular functions. We examined the effect of micelles of mono- and trisialoganglioside GM1 and GT1b on the production of reactive oxygen species by stimulated human polymorphonuclear neutrophils using different spectroscopic methods. The results indicated that exogenous gangliosides did not influence extracellular superoxide anion (O2.- generation by polymorphonuclear neutrophils activated by receptor-dependent formyl-methionyl-leucyl-phenylalanine. However, when neutrophils were stimulated by receptor-bypassing phorbol 12-myristate 13-acetate (PMA, gangliosides above their critical micellar concentrations prolonged the lag time preceding the production in a concentration-dependent way, without affecting total extracellular O2.- generation detected by superoxide dismutase-inhibitable cytochrome c reduction. The effect of ganglioside GT1b (100 µM on the increase in lag time was shown to be significant by means of both superoxide dismutase-inhibitable cytochrome c reduction assay and electron paramagnetic resonance spectroscopy (P < 0.0001 and P < 0.005, respectively. The observed phenomena can be attributed to the ability of ganglioside micelles attached to the cell surface to slow down PMA uptake, thus increasing the diffusion barrier and consequently delaying membrane events responsible for PMA-stimulated O2.- production.

  4. Encapsulation of GFP in Complex Coacervate Core Micelles.

    Science.gov (United States)

    Nolles, Antsje; Westphal, Adrie H; de Hoop, Jacob A; Fokkink, Remco G; Kleijn, J Mieke; van Berkel, Willem J H; Borst, Jan Willem

    2015-05-11

    Protein encapsulation with polymers has a high potential for drug delivery, enzyme protection and stabilization. Formation of such structures can be achieved by the use of polyelectrolytes to generate so-called complex coacervate core micelles (C3Ms). Here, encapsulation of enhanced green fluorescent protein (EGFP) was investigated using a cationic-neutral diblock copolymer of two different sizes: poly(2-methyl-vinyl-pyridinium)41-b-poly(ethylene-oxide)205 and poly(2-methyl-vinyl-pyridinium)128-b-poly(ethylene-oxide)477. Dynamic light scattering and fluorescence correlation spectroscopy (FCS) revealed a preferred micellar composition (PMC) with a positive charge composition of 0.65 for both diblock copolymers and micellar hydrodynamic radii of approximately 34 nm. FCS data show that at the PMC, C3Ms are formed above 100 nM EGFP, independent of polymer length. Mixtures of EGFP and nonfluorescent GFP were used to quantify the amount of GFP molecules per C3M, resulting in approximately 450 GFPs encapsulated per micelle. This study shows that FCS can be successfully applied for the characterization of protein-containing C3Ms.

  5. Compound exocytosis of casein micelles in mammary epithelial cells.

    Science.gov (United States)

    Dylewski, D P; Keenan, T W

    1983-07-01

    Ultrastructure of lactating bovine and rat mammary epithelial cells was studied with emphasis on secretory vesicle interactions. In the apical zone of the cell, adjacent secretory vesicles formed ball and socket configurations at their points of apposition. Similar configurations were formed between plasma membrane and secretory vesicle membrane. These structures may be formed by the diffusion of water between vesicles with different osmotic potentials. Frequently, vesicular chains consisting of 10 or more linked secretory vesicles were observed. Prior to the exocytotic release of casein micelles, adjacent vesicles fused through fragmentation of the ball and socket membrane. These membrane fragments and the casein micelles appeared to be secreted into the alveolar lumen after passing from one vesicle into another and finally through a pore in the apical plasma membrane. Emptied vesicular chains appeared to collapse and fragmentation of their membrane was observed. Based on these observations, we suggest that most vesicular membrane does not directly contact or become incorporated into the plasma membrane during secretion of the nonfat phase of milk.

  6. Effect of sodium deoxycholate and sodium cholate on DPPC vesicles: A fluorescence anisotropy study with diphenylhexatriene

    Indian Academy of Sciences (India)

    Usharani Subuddhi; Ashok K Mishra

    2007-03-01

    Effects of two bile salts, namely sodium deoxycholate (NaDC) and sodium cholate (NaC), on DPPC small unilamellar vesicles have been investigated using the steady-state fluorescence anisotropy () of diphenylhexatriene (DPH) as a tool. It was found that the variation of is sensitive enough to monitor different stages of interaction of bile salts with DPPC vesicles. NaDC induced significant changes in the membrane well below its CMC (6 mM). Even at 4 mM, which is still lower than the CMC, the phospholipids were completely solubilised by the NaDC micelles. The effect of NaC on DPPC vesicles, however, was much less significant, especially in the sub-micellar concentration regime. Being more hydrophilic NaC does not interact with the membrane efficiently. Complete solubilisation of phospholipids took place only when the concentration of NaC was above its CMC (16 mM). The experiments also showed that the bile salt-induced changes of vesicle structure were strongly dependent on the concentration of the bile salt and not on the molar ratio of lipid and bile salt.

  7. Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, D.A.; Herting, D.L.

    1984-09-01

    Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables.

  8. Production of Fluconazole-Loaded Polymeric Micelles Using Membrane and Microfluidic Dispersion Devices

    Directory of Open Access Journals (Sweden)

    Yu Lu

    2016-05-01

    Full Text Available Polymeric micelles with a controlled size in the range between 41 and 80 nm were prepared by injecting the organic phase through a microengineered nickel membrane or a tapered-end glass capillary into an aqueous phase. The organic phase was composed of 1 mg·mL−1 of PEG-b-PCL diblock copolymers with variable molecular weights, dissolved in tetrahydrofuran (THF or acetone. The pore size of the membrane was 20 μm and the aqueous/organic phase volumetric flow rate ratio ranged from 1.5 to 10. Block copolymers were successfully synthesized with Mn ranging from ~9700 to 16,000 g·mol−1 and polymeric micelles were successfully produced from both devices. Micelles produced from the membrane device were smaller than those produced from the microfluidic device, due to the much smaller pore size compared with the orifice size in a co-flow device. The micelles were found to be relatively stable in terms of their size with an initial decrease in size attributed to evaporation of residual solvent rather than their structural disintegration. Fluconazole was loaded into the cores of micelles by injecting the organic phase composed of 0.5–2.5 mg·mL−1 fluconazole and 1.5 mg·mL−1 copolymer. The size of the drug-loaded micelles was found to be significantly larger than the size of empty micelles.

  9. Spectral Properties and Solubilization Location of 2'-Ethylhexyl 4-(N,N-Dimethylamino)benzoate in Micelles

    Institute of Scientific and Technical Information of China (English)

    Ning Ding; Xin-zhen Du; Chun Wang; Xiao-quan Lu

    2008-01-01

    Dual fluorescence and UV absorption of 2'-ethylhexyl 4-(N,N-dimethylamino)benzoate (EHDMAB) were investigated in cationic,non-ionic and anionic miceUes.When EHDMAB was solubilized in different micellss, the UV absorption of EHDMAB was enhanced.Twisted intramolecular charge transfer (TICT) emission with longer wavelength was observed in ionic micelles,whereas TICT emission with shorter wavelength was obtained in non-ionic micelles.In particular,dual fluorescence of EHDMAB was significantly quenched by the positively charged pyridinium ions arranged in the Stern layer of cationic micelles.UV radiation absorbed mainly decays via TICT emission and radiationless deactivation.The dimethylamino group of EHDMAB experiences different polar environments in ionic and non-ionic micelles according to the polarity dependence of TICT emission of EHDMAB in organic solvents.In terms of the molecular structures and sizes of EHDMAB and surfactants,each individual EHDMAB molecule should be buried in micelles with its dimethylamino group toward the polar head groups of different micelles and with its 2'-ethylhexyl chain toward the hydrophobic micellar core.Dynamic fluorescence quenching measurements of EHDMAB provide further support for the location of EHDMAB in different micelles.

  10. A micelle-like structure of poloxamer-methotrexate conjugates as nanocarrier for methotrexate delivery.

    Science.gov (United States)

    Ren, Jin; Fang, Zhengjie; Yao, Li; Dahmani, Fatima Zohra; Yin, Lifang; Zhou, Jianping; Yao, Jing

    2015-06-20

    The purpose of this study was to develop a novel featured and flexible methotrexate (MTX) formulation, in which MTX was physically entrapped and chemically conjugated in the same drug delivery system. A series of poloxamer-MTX (p-MTX) conjugates was synthesized, wherein MTX was grafted to poloxamer through an ester bond. p-MTX conjugates could self-assemble into micelle-like structures in aqueous environment and the MTX end was in the inner-core of micelles. Moreover, free MTX could be physically entrapped into p-MTX micelles hydrophobic core region to increase the total drug loading. Importantly, the resulting MTX-loaded p-MTX micelles showed a biphasic release of MTX, with a relative fast release of the entrapped MTX (about 6-7h) followed by a sustained release of the conjugated MTX. The pharmacokinetics study showed that the mean residence time (MRT) was extended in the case of MTX-loaded p-MTX micelles, indicating a delayed MTX elimination from the bloodstream and prolonged in vivo residence time. Besides, the area under curve (AUC) of MTX-loaded p-MTX micelles was greater than free MTX, indicating a drug bioavailability improvement. Overall, MTX-loaded p-MTX micelles might be a promising nanosized drug delivery system for the cancer therapy.

  11. Bone-targeted acid-sensitive doxorubicin conjugate micelles as potential osteosarcoma therapeutics.

    Science.gov (United States)

    Low, Stewart A; Yang, Jiyuan; Kopeček, Jindřich

    2014-11-19

    Osteosarcoma is a malignancy of the bone that primarily affects adolescents. Current treatments retain mortality rates, which are higher than average cancer mortality rates for the adolescent age group. We designed a micellar delivery system with the aim to increase drug accumulation in the tumor and potentially reduce side effects associated with chemotherapy. The design features are the use of the hydrophilic D-aspartic acid octapeptide as both the effective targeting agent as well as the hydrophilic micelle corona. Micelle stabilization was accomplished by binding of model drug (doxorubicin) via an acid-sensitive hydrazone bond and incorporating one to four 11-aminoundecanoic acid (AUA) moieties to manipulate the hydrophobic/hydrophilic ratio. Four micelle-forming unimers have been synthesized and their self-assembly into micelles was evaluated. Size of the micelles could be modified by changing the architecture of the unimers from linear to branched. The stability of the micelles increased with increasing content of AUA moieties. Adsorption of all micelles to hydroxyapatite occurred rapidly. Doxorubicin release occurred at pH 5.5, whereas no release was detected at pH 7.4. Cytotoxicity toward human osteosarcoma Saos-2 cells correlated with drug release data.

  12. Production of Fluconazole-Loaded Polymeric Micelles Using Membrane and Microfluidic Dispersion Devices

    Science.gov (United States)

    Lu, Yu; Chowdhury, Danial; Vladisavljević, Goran T.; Koutroumanis, Konstantinos; Georgiadou, Stella

    2016-01-01

    Polymeric micelles with a controlled size in the range between 41 and 80 nm were prepared by injecting the organic phase through a microengineered nickel membrane or a tapered-end glass capillary into an aqueous phase. The organic phase was composed of 1 mg·mL−1 of PEG-b-PCL diblock copolymers with variable molecular weights, dissolved in tetrahydrofuran (THF) or acetone. The pore size of the membrane was 20 μm and the aqueous/organic phase volumetric flow rate ratio ranged from 1.5 to 10. Block copolymers were successfully synthesized with Mn ranging from ~9700 to 16,000 g·mol−1 and polymeric micelles were successfully produced from both devices. Micelles produced from the membrane device were smaller than those produced from the microfluidic device, due to the much smaller pore size compared with the orifice size in a co-flow device. The micelles were found to be relatively stable in terms of their size with an initial decrease in size attributed to evaporation of residual solvent rather than their structural disintegration. Fluconazole was loaded into the cores of micelles by injecting the organic phase composed of 0.5–2.5 mg·mL−1 fluconazole and 1.5 mg·mL−1 copolymer. The size of the drug-loaded micelles was found to be significantly larger than the size of empty micelles. PMID:27231945

  13. Effect of the lipid chain melting transition on the stability of DSPE-PEG(2000) micelles.

    Science.gov (United States)

    Kastantin, Mark; Ananthanarayanan, Badriprasad; Karmali, Priya; Ruoslahti, Erkki; Tirrell, Matthew

    2009-07-01

    Micellar nanoparticles are showing promise as carriers of diagnostic and therapeutic biofunctionality, leading to increased interest in their properties and behavior, particularly their size, shape, and stability. This work investigates the physical chemistry of micelles formed from DSPE-PEG(2000) monomers as it pertains to these properties. A melting transition in the lipid core of spheroidal DSPE-PEG(2000) micelles is observed as an endothermic peak at 12.8 degrees C upon heating in differential scanning calorimetry thermograms. Bulky PEG(2000) head groups prevent regular crystalline packing of lipids in both the low-temperature glassy and high-temperature fluid phases, as evidenced by wide-angle X-ray scattering. Equilibrium micelle geometry is spheroidal above and below the transition temperature, indicating that the entropic penalty to force the PEG brush into flat geometry is greater than the enthalpic benefit to the glassy core to pack in an extended configuration. Increased micelle stability is seen in the glassy phase with monomer desorption rates significantly lower than in the fluid phase. Activation energies for monomer desorption are 156+/-6.7 and 79+/-5.0 kJ/mol for the glassy and fluid phases, respectively. The observation of a glass transition that increases micelle stability but does not perturb micelle geometry is useful for the design of more effective biofunctional micelles.

  14. How to squeeze a sponge: casein micelles under osmotic stress, a SAXS study.

    Science.gov (United States)

    Bouchoux, Antoine; Gésan-Guiziou, Geneviève; Pérez, Javier; Cabane, Bernard

    2010-12-01

    By combining the osmotic stress technique with small-angle x-ray scattering measurements, we followed the structural response of the casein micelle to an overall increase in concentration. When the aqueous phase that separates the micelles is extracted, they behave as polydisperse repelling spheres and their internal structure is not affected. When they are compressed, the micelles lose water and shrink to a smaller volume. Our results indicate that this compression is nonaffine, i.e., some parts of the micelle collapse, whereas other parts resist deformation. We suggest that this behavior is consistent with a spongelike casein micelle having a triple hierarchical structure. The lowest level of the structure consists of the CaP nanoclusters that serve as anchors for the casein molecules. The intermediate level consists of 10- to 40-nm hard regions that resist compression and contain the nanoclusters. Those regions are connected and/or partially merged with each other, thus forming a continuous and porous material. The third level of structure is the casein micelle itself, with an average size of 100 nm. In our view, such a structure is consistent with the observation of 10- to 20-nm casein particles in the Golgi vesicles of lactating cells: upon aggregation, those particles would rearrange, fuse, and/or swell to form the spongelike micelle.

  15. Octreotide-functionalized and resveratrol-loaded unimolecular micelles for targeted neuroendocrine cancer therapy

    Science.gov (United States)

    Xu, Wenjin; Burke, Jocelyn F.; Pilla, Srikanth; Chen, Herbert; Jaskula-Sztul, Renata; Gong, Shaoqin

    2013-09-01

    Medullary thyroid cancer (MTC) is a neuroendocrine tumor (NET) that is often resistant to standard therapies. Resveratrol suppresses MTC growth in vitro, but it has low bioavailability in vivo due to its poor water solubility and rapid metabolic breakdown, as well as lack of tumor-targeting ability. A novel unimolecular micelle based on a hyperbranched amphiphilic block copolymer was designed, synthesized, and characterized for NET-targeted delivery. The hyperbranched amphiphilic block copolymer consisted of a dendritic Boltorn® H40 core, a hydrophobic poly(l-lactide) (PLA) inner shell, and a hydrophilic poly(ethylene glycol) (PEG) outer shell. Octreotide (OCT), a peptide that shows strong binding affinity to somatostatin receptors, which are overexpressed on NET cells, was used as the targeting ligand. Resveratrol was physically encapsulated by the micelle with a drug loading content of 12.1%. The unimolecular micelles exhibited a uniform size distribution and spherical morphology, which were determined by both transmission electron microscopy (TEM) and dynamic light scattering (DLS). Cellular uptake, cellular proliferation, and Western blot analyses demonstrated that the resveratrol-loaded OCT-targeted micelles suppressed growth more effectively than non-targeted micelles. Moreover, resveratrol-loaded NET-targeted micelles affected MTC cells similarly to free resveratrol in vitro, with equal growth suppression and reduction in NET marker production. These results suggest that the H40-based unimolecular micelle may offer a promising approach for targeted NET therapy.

  16. Thermal responsive micelles for dual tumor-targeting imaging and therapy

    Science.gov (United States)

    Chen, Haiyan; Li, Bowen; Qiu, Jiadan; Li, Jiangyu; Jin, Jing; Dai, Shuhang; Ma, Yuxiang; Gu, Yueqing

    2013-11-01

    Two kinds of thermally responsive polymers P(FAA-NIPA-co-AAm-co-ODA) and P(FPA-NIPA-co-AAm-co-ODA) containing folate, isopropyl acrylamide and octadecyl acrylate were fabricated through free radical random copolymerization for targeted drug delivery. Then the micelles formed in aqueous solution by self-assembly and were characterized in terms of particle size, lower critical solution temperature (LCST) and a variety of optical spectra. MTT assays demonstrated the low cytotoxicity of the control micelle and drug-loaded micelle on A549 cells and Bel 7402 cells. Then fluorescein and cypate were used as model drugs to optimize the constituents of micelles for drug entrapment efficiency and investigate the release kinetics of micelles in vitro. The FA and thermal co-mediated tumor-targeting efficiency of the two kinds of micelles were verified and compared in detail at cell level and animal level, respectively. These results indicated that the dual-targeting micelles are promising drug delivery systems for tumor-targeting therapy.

  17. Cholesterol-Enhanced Polylactide-Based Stereocomplex Micelle for Effective Delivery of Doxorubicin

    Directory of Open Access Journals (Sweden)

    Jixue Wang

    2015-01-01

    Full Text Available Nanoscale micelles as an effective drug delivery system have attracted increasing interest in malignancy therapy. The present study reported the construction of the cholesterol-enhanced doxorubicin (DOX-loaded poly(D-lactide-based micelle (CDM/DOX, poly(L-lactide-based micelle (CLM/DOX, and stereocomplex micelle (CSCM/DOX from the equimolar enantiomeric 4-armed poly(ethylene glycol–polylactide copolymers in aqueous condition. Compared with CDM/DOX and CLM/DOX, CSCM/DOX showed the smallest hydrodynamic size of 96 ± 4.8 nm and the slowest DOX release. The DOX-loaded micelles exhibited a weaker DOX fluorescence inside mouse renal carcinoma cells (i.e., RenCa cells compared to free DOX·HCl, probably because of a slower DOX release. More importantly, all the DOX-loaded micelles, especially CSCM/DOX, exhibited the excellent antiproliferative efficacy that was equal to or even better than free DOX·HCl toward RenCa cells attributed to their successful internalization. Furthermore, all of the DOX-loaded micelles exhibited the satisfactory hemocompatibility compared to free DOX·HCl, indicating the great potential for systemic chemotherapy through intravenous injection.

  18. Inhibited phenol ionization in reverse micelles: confinement effect at the nanometer scale.

    Science.gov (United States)

    Silva, O Fernando; Fernández, Mariana A; Silber, Juana J; de Rossi, Rita H; Correa, N Mariano

    2012-01-16

    We found that the absorption spectra of 2-acetylphenol (2-HAP), 4-acetylphenol (4-HAP), and p-nitrophenol (p-NPh) in water/sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT)/n-heptane reverse micelles (RMs) at various W(0) (W(0) = [H(2)O]/[surfactant]) values studied changed with time if (-)OH ions were present in the RM water pool. There is an evolution of ionized phenol (phenolate) bands to nonionized phenol absorption bands with time and this process is faster at low W(0) values and with phenols with higher bulk water pK(a) values. That is, in bulk water and at the hydroxide anion concentration used, only phenolate species are observed, whereas in AOT RMs at this fixed hydroxide anion concentration, ionized phenols convert into nonionized phenol species over time. Furthermore, we demonstrate that, independent of the (-)OH concentration used to prepare the AOT RMs, the nonionized phenols are the more stable species in the RM media. We explain our results by considering that strong hydrogen-bonding interactions between phenols and the AOT polar head groups result in the existence of only nonionized phenols at the AOT RM interface. The situation is quite different when the phenols are dissolved in cationic benzyl-n-hexadecyldimethylammonium chloride RMs. Therein, only phenolates species are present at the (-)OH concentrations used. The results clearly demonstrate that the classical definition of pH does not apply in a confined environment, such as in the interior of RMs and challenge the general idea that pH can be determined inside RMs.

  19. Extraction of monoclonal antibodies (IgG1) using anionic and anionic/nonionic reverse micelles.

    Science.gov (United States)

    George, Daliya A; Stuckey, David C

    2010-01-01

    Purification schemes for antibody production based on affinity chromatography are trying to keep pace with increases in cell culture expression levels and many current research initiatives are focused on finding alternatives to chromatography for the purification of Monoclonal antibodies (MAbs). In this article, we have investigated an alternative separation technique based on liquid-liquid extraction called the reverse micellar extraction. We extracted MAb (IgG1) using reverse micelles of an anionic surfactant, sodium bis 2-ethyl-hexyl sulfosuccinate (AOT) and a combination of anionic (AOT) and nonionic surfactants (Brij-30, Tween-85, Span-85) using isooctane as the solvent system. The extraction efficiency of IgG1 was studied by varying parameters, such as pH of the aqueous phase, cation concentration, and type and surfactant concentration. Using the AOT/Isooctane reverse micellar system, we could achieve good overall extraction of IgG1 (between 80 and 90%), but only 30% of the bioactivity of IgG1 could be recovered at the end of the extraction by using its binding to affinity chromatography columns as a surrogate measure of activity. As anionic surfactants were suspected as being one of the reasons for the reduced activity, we decided to combine a nonionic surfactant with an anionic surfactant and then study its effect on the extraction efficiency and bioactivity. The best results were obtained using an AOT/Brij-30/Isooctane reverse micellar system, which gave an overall extraction above 90 and 59% overall activity recovery. An AOT/Tween-85/Isooctane reverse micellar system gave an overall extraction of between 75 and 80% and overall activity recovery of around 40-45%. The results showed that the activity recovery of IgG1 can be significantly enhanced using different surfactant combination systems, and if the recovery of IgG1 can be further enhanced, the technique shows considerable promise for the downstream purification of MAbs.

  20. Backbone-hydrazone-containing biodegradable copolymeric micelles for anticancer drug delivery

    Science.gov (United States)

    Xu, Jing; Luan, Shujuan; Qin, Benkai; Wang, Yingying; Wang, Kai; Qi, Peilan; Song, Shiyong

    2016-11-01

    Well-defined biodegradable, pH-sensitive amphiphilic block polymers, poly(ethylene glycol)-Hyd-poly(lactic acid) (mPEG-Hyd-PLA) which have acid-cleavable linkages in their backbones, were synthesized via ring-opening polymerization initiated from hydrazone-containing macroinitiators. Introducing a hydrazone bond onto the backbone of an amphiphilic copolymer will find a broad-spectrum encapsulation of hydrophobic drugs. Dynamic light scattering (DLS) and transmission electron microscopy showed that the diblock copolymers self-assembled into stable micelles with average diameters of 100 nm. The mean diameters and size distribution of the hydrazone-containing micelles changed obviously in mildly acidic pH (multiple peaks from 1 to 202 nm appeared under a pH 4.0 condition) than in neutral, while there were no changes in the case of non-sensitive ones. Doxorubicin (DOX) and paclitaxel (PTX) were loaded with drug loading content ranging from 2.4 to 3.5 %, respectively. Interestingly, the anticancer drugs released from mPEG-Hyd-PLA micelles could also be promoted by the increased acidity. An in vitro cytotoxicity study showed that the DOX-loaded mPEG-Hyd-PLA micelles have significantly enhanced cytotoxicity against HepG2 cells compared with the non-sensitive poly(ethylene glycol)-block-poly(lactic acid) (mPEG-PLA) micelles. Confocal microscopy observation indicated that more DOX were delivered into the nuclei of cells following 6 or 12 h incubation with DOX-loaded mPEG-Hyd-PLA micelles. In vivo studies on H22-bearing Swiss mice demonstrated the superior anticancer activity of DOX-loaded mPEG-Hyd-PLA micelles over free DOX and DOX-loaded mPEG-PLA micelles. These hydrazone-containing pH-responsive degradable micelles provide a useful strategy for antitumor drug delivery.

  1. Catalytic performance and thermostability of chloroperoxidase in reverse micelle: achievement of a catalytically favorable enzyme conformation.

    Science.gov (United States)

    Wang, Yali; Wu, Jinyue; Ru, Xuejiao; Jiang, Yucheng; Hu, Mancheng; Li, Shuni; Zhai, Quanguo

    2011-06-01

    The catalytic performance of chloroperoxidase (CPO) in peroxidation of 2, 2'-azinobis-(-3 ethylbenzothiazoline-6-sulfononic acid) diammonium salt (ABTS) and oxidation of indole in a reverse micelle composed of surfactant-water-isooctane-pentanol was investigated and optimized in this work. Some positive results were obtained as follows: the peroxidation activity of CPO was enhanced 248% and 263%, while oxidation activity was enhanced 215% and 222% in cetyltrimethylammonium bromide (CTABr) reverse micelle medium and dodecyltrimethylammonium bromide (DTABr) medium, respectively. Thermostability was also greatly improved in reverse micelle: at 40 °C, CPO essentially lost all its activity after 5 h incubation, while 58-76% catalytic activity was retained for both reactions in the two reverse micelle media. At 50 °C, about 44-75% catalytic activity remained for both reactions in reverse micelle after 2 h compared with no observed activity in pure buffer under the same conditions. The enhancement of CPO activity was dependent mainly on the surfactant concentration and structure, organic solvent ratio (V(pentanol)/V(isooctane)), and water content in the reverse micelle. The obtained kinetic parameters showed that the catalytic turnover frequency (k(cat)) was increased in reverse micelle. Moreover, the lower K(m) and higher k(cat)/K(m) demonstrated that both the affinity and specificity of CPO to substrates were improved in reverse micelle media. Fluorescence, circular dichroism (CD) and UV-vis spectra assays indicated that a catalytically favorable conformation of enzyme was achieved in reverse micelle, including the strengthening of the protein α-helix structure, and greater exposure of the heme prosthetic group for easy access of the substrate in bulk solution. These results are promising in view of the industrial applications of this versatile biological catalyst.

  2. Novel micelle formulation of curcumin for enhancing antitumor activity and inhibiting colorectal cancer stem cells

    Directory of Open Access Journals (Sweden)

    Wang K

    2012-08-01

    Full Text Available Ke Wang,1 Tao Zhang,1 Lina Liu,2 Xiaolei Wang,1 Ping Wu,1 Zhigang Chen,1 Chao Ni,1 Junshu Zhang,1 Fuqiang Hu,4 Jian Huang1,31Cancer Institute, 2Department of Pharmacy, Second Affiliated Hospital (Binjiang Branch, 3Department of Oncology, Second Affiliated Hospital, Zhejiang University School of Medicine, 4College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, ChinaBackground and methods: Curcumin has extraordinary anticancer properties but has limited use due to its insolubility in water and instability, which leads to low systemic bioavailability. We have developed a novel nanoparticulate formulation of curcumin encapsulated in stearic acid-g-chitosan oligosaccharide (CSO-SA polymeric micelles to overcome these hurdles.Results: The synthesized CSO-SA copolymer was able to self-assemble to form nanoscale micelles in aqueous medium. The mean diameter of the curcumin-loaded CSO-SA micelles was 114.7 nm and their mean surface potential was 18.5 mV. Curcumin-loaded CSO-SA micelles showed excellent internalization ability that increased curcumin accumulation in cancer cells. Curcumin-loaded CSO-SA micelles also had potent antiproliferative effects on primary colorectal cancer cells in vitro, resulting in about 6-fold greater inhibition compared with cells treated with a solution containing an equivalent concentration of free curcumin. Intravenous administration of curcumin-loaded CSO-SA micelles marginally suppressed tumor growth but did not increase cytotoxicity to mice, as confirmed by no change in body weight. Most importantly, curcumin-loaded CSO-SA micelles were effective for inhibiting subpopulations of CD44+/CD24+ cells (putative colorectal cancer stem cell markers both in vitro and in vivo.Conclusion: The present study identifies an effective and safe means of using curcumin-loaded CSO-SA micelles for cancer therapy.Keywords: chitosan oligosaccharide, polymeric micelle, curcumin, drug delivery, colorectal cancer, cancer stem cells

  3. The Effect of Hydrophilic and Hydrophobic Structure of Amphiphilic Polymeric Micelles on Their Transportation in Rats.

    Science.gov (United States)

    Deng, Feiyang; Yu, Chao; Zhang, Hua; Dai, Wenbing; He, Bing; Zheng, Ying; Wang, Xueqing; Zhang, Qiang

    2016-01-01

    In the previous study, we have clarified how the hydrophilic and hydrophobic structures of amphiphilic polymers impact the transport of their micelles (PEEP-PCL, PEG-PCL and PEG-DSPE micelles) in epithelial MDCK cells (Biomaterials 2013, 34: 6284-6298). In this study, we attempt to clarify the behavior of the three micelles in rats. Coumarin-6 loaded micelles were injected into different sections of intestine of rats and observed by confocal laser scanning microscope (CLSM) or orally administrated and conducted pharmacokinetic study. All of the three kinds of micelles were able to cross the intestinal epithelial cells and enter blood circulation. The PEEP-PCL micelles demonstrated the fastest distribution mainly in duodenum, while the PEGDSPE micelles showed the longest distribution with the highest proportion in ileum of the three. No significant difference was observed among the pharmacokinetic parameters of the three micelles. The results were consistent in the two analysis methods mentioned above, yet there were some differences between in vivo and in vitro results reported previously. It might be the distinction between the environments in MDCK model and intestine that led to the discrepancy. The hydrophobicity of nanoparticles could both enhance uptake and hinder the transport across the mucus. However, there was no intact mucus in MDCK model, which preferred hydrophobic nanoparticles. PEEP was the most hydrophilic material constructing the micelles in the study and its uptake would be increased in rats compared to that in MDCK model, while DSPE was more hydrophobic than the others and MDCK model would be more ideal for its uptake. Considering the inconsistency of the results in the two models, whether the methods researchers were generally using at present were reasonable needs further investigation.

  4. pH-responsive layer-by-layer films of zwitterionic block copolymer micelles

    OpenAIRE

    Demirel, Adem Levent; Yusan, Pelin; Tuncel, İrem; Bütün, Vural; Erel-Goktepe, İrem

    2014-01-01

    We report a strategy to incorporate micelles of poly[3-dimethyl (methacryloyloxyethyl) ammonium propane sulfonate]-block-poly[2-(diisopropylamino) ethyl methacrylate] (beta PDMA-b-PDPA) into electrostatic layer-by-layer (LbL) films. We obtained micelles with pH-responsive PDPA-cores and zwitterionic bPDMA-coronae at pH 8.5 through pH-induced self-assembly of bPDMA-b-PDPA in aqueous solution. To incorporate bPDMA-b-PDPA micelles into LbL films, we first obtained a net electrical charge on bPDM...

  5. Counterion condensation in ionic micelles as studied by a combined use of SANS and SAXS

    Indian Academy of Sciences (India)

    V K Aswal; P S Goyal; H Amenitsch; S Bernstorff

    2004-08-01

    We report a combined use of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) to the study of counterion condensation in ionic micelles. Small-angle neutron and X-ray scattering measurements have been carried out on two surfactants cetyltrimethylammonium bromide (CTABr) and cetyltrimethylammonium chloride (CTACl), which are similar but having different counterions. SANS measurements show that CTABr surfactant forms much larger micelles than CTACl. This is explained in terms of higher condensation of Br0 counterions than Cl- counterions. SAXS data on these systems suggest that the Br- counterions are condensed around the micelles over smaller thickness than those of Cl- counterions.

  6. Dissipative particle dynamics simulation on paclitaxel loaded PEO-PPO-PEO block copolymer micelles.

    Science.gov (United States)

    Wang, Zhigao; Jiang, Jie

    2014-03-01

    Self-assembly behavior of the polymer drug loading micelle PEO-PPO-PEO was studied using dissipative particle dynamics (DPD) simulation method with various simulation steps. The distributions of drugs in polymer carriers were also investigated with different drug feed ratios. Polymer carriers distributed on the surface of the spherical micelle, and drugs were almost encapsulated in the inner of the micelle. Our simulation work demonstrates that the DPD simulation is effective to study the drug loaded systems and can give useful guidance on the design and preparation of new drug carriers with tailored properties.

  7. Cation-π Interaction between the Aromatic Organic Counterion and DTAB Micelle in Mixed Solvents

    Institute of Scientific and Technical Information of China (English)

    DENG,Dong-Shun(邓东顺); LI,Hao-Ran(李浩然); LIU,Di-Xia(刘迪霞); HAN,Shi-Jun(韩世钧)

    2004-01-01

    The cation-π interaction between the aromatic organic counterion potassium hydrogen phthalate (KHP) and DTAB micelle in aqueous mixture of EG was investigated, using the techniques of conductivity measurements, UV absorption spectrum and NMR spectrum. The conductivity and UV spectrum studies were with respect to the effect of KHP on DTAB and that of DTAB micelle on KHP, respectively. According to the chemical shift changes of the aromatic ring and the surfactant methylene protons, it can be assumed that KHP penetrated into DTAB micelle with its carboxylic group protruding out of the micellar surface. And the strength of the interaction became weaker with the content of EG in the mixed solvent increasing.

  8. Complement monitoring of Pluronic 127 gel and micelles

    DEFF Research Database (Denmark)

    Hamad, Islam; Hunter, A Christy; Moghimi, Seyed Moien

    2013-01-01

    Poloxamer 407 is a non-ionic polyethylene oxide (PEO)/polypropylene oxide (PPO) block copolymer, which exhibits reversible thermogelation properties. Poloxamer gel has attracted many applications for controlled release of therapeutic agents as well as in surgical interventions such as controlled...... vascular occlusion. We show that poloxamer gel can trigger the complement system, which is an integral part of innate immunity and its inadvertent activation can induce clinically significant anaphylaxis. Complement activation by the poloxamer gel is through the alternative pathway, but material...... transformations from gel to the solution state further incite complement through calcium-sensitive pathways, where a role for C1q and antibodies has been eliminated. Poloxamer addition to plasma/serum (at levels above its critical micelle concentration, cmc) induced formation of large and diffused structures...

  9. Cooperative catalysis with block copolymer micelles: a combinatorial approach.

    Science.gov (United States)

    Bukhryakov, Konstantin V; Desyatkin, Victor G; O'Shea, John-Paul; Almahdali, Sarah R; Solovyeva, Vera; Rodionov, Valentin O

    2015-02-09

    A rapid approach to identifying complementary catalytic groups using combinations of functional polymers is presented. Amphiphilic polymers with "clickable" hydrophobic blocks were used to create a library of functional polymers, each bearing a single functionality. The polymers were combined in water, yielding mixed micelles. As the functional groups were colocalized in the hydrophobic microphase, they could act cooperatively, giving rise to new modes of catalysis. The multipolymer "clumps" were screened for catalytic activity, both in the presence and absence of metal ions. A number of catalyst candidates were identified across a wide range of model reaction types. One of the catalytic systems discovered was used to perform a number of preparative-scale syntheses. Our approach provides easy access to a range of enzyme-inspired cooperative catalysts.

  10. Cooperative catalysis with block copolymer micelles: A combinatorial approach

    KAUST Repository

    Bukhryakov, Konstantin V.

    2015-02-09

    A rapid approach to identifying complementary catalytic groups using combinations of functional polymers is presented. Amphiphilic polymers with "clickable" hydrophobic blocks were used to create a library of functional polymers, each bearing a single functionality. The polymers were combined in water, yielding mixed micelles. As the functional groups were colocalized in the hydrophobic microphase, they could act cooperatively, giving rise to new modes of catalysis. The multipolymer "clumps" were screened for catalytic activity, both in the presence and absence of metal ions. A number of catalyst candidates were identified across a wide range of model reaction types. One of the catalytic systems discovered was used to perform a number of preparative-scale syntheses. Our approach provides easy access to a range of enzyme-inspired cooperative catalysts.

  11. Structure-Property Relationships for Branched Worm-Like Micelles

    Science.gov (United States)

    Beaucage, Gregory; Rai, Durgesh

    2013-03-01

    Micellar solutions can display a wide range of phase structure as a function of counter ion content, surfactant concentration, and the presence of ternary components. Under some conditions, common to consumer products, extended cylindrical structures that display persistence and other chain features of polymers are produced. These worm-like micelles (WLMs) can form branched structures that dynamically change under shear and even in quiescent conditions. The rheology of these branched WLMs is strongly dependent on migration of the branch points, and the dynamics of branch formation and removal. Persistence and other polymer-based descriptions are also of importance. We have recently developed a scattering model for branched polyolefins and other topologically complex materials that can quantify the branching density, branch length, branch functionality and the hyperbranch (branch-on-branch) content of polymers. This work is being extended to study branching in WLMs in work coupled with Ron Larson at UMich to predict rheological properties.

  12. Thermodynamics of sodium dodecyl sulphate-salicylic acid based micellar systems and their potential use in fruits postharvest.

    Science.gov (United States)

    Cid, A; Morales, J; Mejuto, J C; Briz-Cid, N; Rial-Otero, R; Simal-Gándara, J

    2014-05-15

    Micellar systems have excellent food applications due to their capability to solubilise a large range of hydrophilic and hydrophobic substances. In this work, the mixed micelle formation between the ionic surfactant sodium dodecyl sulphate (SDS) and the phenolic acid salicylic acid have been studied at several temperatures in aqueous solution. The critical micelle concentration and the micellization degree were determined by conductometric techniques and the experimental data used to calculate several useful thermodynamic parameters, like standard free energy, enthalpy and entropy of micelle formation. Salicylic acid helps the micellization of SDS, both by increasing the additive concentration at a constant temperature and by increasing temperature at a constant concentration of additive. The formation of micelles of SDS in the presence of salicylic acid was a thermodynamically spontaneous process, and is also entropically controlled. Salicylic acid plays the role of a stabilizer, and gives a pathway to control the three-dimensional water matrix structure. The driving force of the micellization process is provided by the hydrophobic interactions. The isostructural temperature was found to be 307.5 K for the mixed micellar system. This article explores the use of SDS-salicylic acid based micellar systems for their potential use in fruits postharvest.

  13. Decode the Sodium Label Lingo

    Science.gov (United States)

    ... For Preschooler For Gradeschooler For Teen Decode the Sodium Label Lingo Published January 24, 2013 Print Email Reading food labels can help you slash sodium. Here's how to decipher them. "Sodium free" or " ...

  14. Kinetic Studies on the Lignin Peroxidase Catalyzed Oxidation of Veratryl Alcohol by H2O2 in AOT/Isooctane/Toluene/Water Reverse Micelles

    Institute of Scientific and Technical Information of China (English)

    LIU Jin-Ting; HUANG Xi-Rong; GAO Pei-ji

    2007-01-01

    The steady state kinetics of the lignin peroxidase (LIP) catalyzed oxidation of veratryl alcohol (VA) by H2O2 in a sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane/toluene/water reverse micellar medium was studied and a comparison with the corresponding aqueous medium was made to understand the effect of the reverse micellar medium on the catalytic mechanism and kinetic parameters. Results indicated that the model reaction in the AOT medium were the same as those in bulk aqueous medium, but the kinetic parameters except Km,H2O2 were greatly different in the two media. The kcat and Ki values in the reverse micelle were approximately 2 and 20 times smaller than the corresponding values in the aqueous solution, but the Michaelis constant of VA was approximately 100times greater than that in the aqueous solution. The above mentioned differences in the kinetic parameters were caused by the microheterogeneity and the interface of the AOT reverse micelle, which resulted in the partitioning of VA and H2O2, and by the changes of the conformation of LiP and the reactivity of the substrates.

  15. Location of ethanol in sodium dodecyl sulfate aggregates

    Institute of Scientific and Technical Information of China (English)

    LIU, Tian-Qing; YU, Wei-Li; GUO, Rong

    2000-01-01

    The hexagonal liquid crystalline phase of SDS ( Sodium dodecyl sulfate)/H2O system changes into lamellar liquid crystal and the effective length of surfactant molecule d0/2 in the lamellar liquid crystal decreases with the addition of ethanol.The micellar aggregation number N of SDS decreases and the micellar diffusion coefficient increases with the added ethanol.Under a constant concentration of SDS, the molecule number ratio of ethanol to SDS in the micelle increases with the concentration of ethanol and even exceeds 10 when ethanol concentration is 1.085 mol/L. All these results show that ethanol, even though a short chain alcohol and soluble in water, can partly exist in the interphase of the amphiphilic aggregates showing some properties of co-surfactant.

  16. Biodegradable polymeric micelle-encapsulated quercetin suppresses tumor growth and metastasis in both transgenic zebrafish and mouse models

    Science.gov (United States)

    Wu, Qinjie; Deng, Senyi; Li, Ling; Sun, Lu; Yang, Xi; Liu, Xinyu; Liu, Lei; Qian, Zhiyong; Wei, Yuquan; Gong, Changyang

    2013-11-01

    Quercetin (Que) loaded polymeric micelles were prepared to obtain an aqueous formulation of Que with enhanced anti-tumor and anti-metastasis activities. A simple solid dispersion method was used, and the obtained Que micelles had a small particle size (about 31 nm), high drug loading, and high encapsulation efficiency. Que micelles showed improved cellular uptake, an enhanced apoptosis induction effect, and stronger inhibitory effects on proliferation, migration, and invasion of 4T1 cells than free Que. The enhanced in vitro antiangiogenesis effects of Que micelles were proved by the results that Que micelles significantly suppressed proliferation, migration, invasion, and tube formation of human umbilical vein endothelial cells (HUVECs). Subsequently, transgenic zebrafish models were employed to investigate anti-tumor and anti-metastasis effects of Que micelles, in which stronger inhibitory effects of Que micelles were observed on embryonic angiogenesis, tumor-induced angiogenesis, tumor growth, and tumor metastasis. Furthermore, in a subcutaneous 4T1 tumor model, Que micelles were more effective in suppressing tumor growth and spontaneous pulmonary metastasis, and prolonging the survival of tumor-bearing mice. Besides, immunohistochemical and immunofluorescent assays suggested that tumors in the Que micelle-treated group showed more apoptosis, fewer microvessels, and fewer proliferation-positive cells. In conclusion, Que micelles, which are synthesized as an aqueous formulation of Que, possess enhanced anti-tumor and anti-metastasis activity, which can serve as potential candidates for cancer therapy.

  17. Development and evaluation of N-naphthyl-N,O-succinyl chitosan micelles containing clotrimazole for oral candidiasis treatment.

    Science.gov (United States)

    Tonglairoum, Prasopchai; Woraphatphadung, Thisirak; Ngawhirunpat, Tanasait; Rojanarata, Theerasak; Akkaramongkolporn, Prasert; Sajomsang, Warayuth; Opanasopit, Praneet

    2017-03-01

    Clotrimazole (CZ)-loaded N-naphthyl-N,O-succinyl chitosan (NSCS) micelles have been developed as an alternative for oral candidiasis treatment. NSCS was synthesized by reductive N-amination and N,O-succinylation. CZ was incorporated into the micelles using various methods, including the dropping method, the dialysis method, and the O/W emulsion method. The size and morphology of the CZ-loaded micelles were characterized using dynamic light scattering measurements (DLS) and a transmission electron microscope (TEM), respectively. The drug entrapment efficiency, loading capacity, release characteristics, and antifungal activity against Candida albicans were also evaluated. The CZ-loaded micelles prepared using different methods differed in the size of micelles. The micelles ranged in size from 120 nm to 173 nm. The micelles prepared via the O/W emulsion method offered the highest percentage entrapment efficiency and loading capacity. The CZ released from the CZ-loaded micelles at much faster rate compared to CZ powder. The CZ-loaded NSCS micelles can significantly hinder the growth of Candida cells after contact. These CZ-loaded NSCS micelles offer great antifungal activity and might be further developed to be a promising candidate for oral candidiasis treatment.

  18. Preparation and Characterization of Copolymer Micelles Formed by Poly(ethylene glycol)-Polylactide Block Copolymers as Novel Drug Carriers

    Institute of Scientific and Technical Information of China (English)

    姜维; 王运东; 甘泉; 张建铮; 赵秀文; 费维扬; 贝建中; 王身国

    2006-01-01

    Diblock copolymer poly(ethylene glycol) methyl ether-polylactide (MePEG-PLA) micelles were prepared by dialysis against water. Indomethacin (IMC) as a model drug was entrapped into the micelles by dialysis method. The critical micelle concentration (CMC) of the prepared micelles in distilled water investigated by fluorescence spectroscopy was 0.0051mg/mL which is lower than that of common low molecular weight surfactants. The diameters of MePEG-PLA micelles and IMC loaded MePEG-PLA micelles in a number-averaged scale measured by dynamic light scattering were 52.4 and 53.7 nm respectively. The observation with transmission electron microscope and scanning electron microscope showed that the appearance of MePEG-PLA micelles was in a spherical shape. The content of IMC incorporated in the core portion of the micelles was 18% (ω). The effects of the synthesis method of the copolymer on the polydispersity of the micelles and the yield of the micelles formation were discussed.

  19. Use of Magnetic Folate-Dextran-Retinoic Acid Micelles for Dual Targeting of Doxorubicin in Breast Cancer

    Directory of Open Access Journals (Sweden)

    J. Varshosaz

    2013-01-01

    Full Text Available Amphiphilic copolymer of folate-conjugated dextran/retinoic acid (FA/DEX-RA was self-assembled into micelles by direct dissolution method. Magnetic iron oxide nanoparticles (MNPs coated with oleic acid (OA were prepared by hydrothermal method and encapsulated within the micelles. Doxorubicin HCl was loaded in the magnetic micelles. The characteristics of the magnetic micelles were determined by Fourier transform infrared (FT-IR spectroscopy, thermogravimetric analysis (TGA, transmission electron microscopy (TEM, and vibrating sample magnetometer (VSM. The crystalline state of OA-coated MNPs and their heat capacity were analyzed by X-ray diffraction (XRD and differential scanning calorimetry (DSC methods, respectively. The iron content of magnetic micelles was determined using inductively coupled plasma optical emission spectrometry (ICP-OES. Bovine serum albumin (BSA was used to test the protein binding of magnetic micelles. The cytotoxicity of doxorubicin loaded magnetic micelles was studied on MCF-7 and MDA-MB-468 cells using MTT assay and their quantitative cellular uptake by fluorimetry method. TEM results showed the MNPs in the hydrophobic core of the micelles. TGA results confirmed the presence of OA and FA/DEX-RA copolymer on the surface of MNPs and micelles, respectively. The magnetic micelles showed no significant protein bonding and reduced the IC50 of the drug to about 10 times lower than the free drug.

  20. Characteristic of core materials in polymeric micelles effect on their micellar properties studied by experimental and dpd simulation methods.

    Science.gov (United States)

    Cheng, Furong; Guan, Xuewa; Cao, Huan; Su, Ting; Cao, Jun; Chen, Yuanwei; Cai, Mengtan; He, Bin; Gu, Zhongwei; Luo, Xianglin

    2015-08-15

    Polymeric micelles are one important class of nanoparticles for anticancer drug delivery, but the impact of hydrophobic segments on drug encapsulation and release is unclear, which deters the rationalization of drug encapsulation into polymeric micelles. This paper focused on studying the correlation between the characteristics of hydrophobic segments and encapsulation of structurally different drugs (DOX and β-carotene). Poly(ϵ-caprolactone) (PCL) or poly(l-lactide) (PLLA) were used as hydrophobic segments to synthesize micelle-forming amphiphilic block copolymers with the hydrophilic methoxy-poly(ethylene glycol) (mPEG). Both blank and drug loaded micelles were spherical in shape with sizes lower than 50 nm. PCL-based micelles exhibited higher drug loading capacity than their PLLA-based counterparts. Higher encapsulation efficiency of β-carotene was achieved compared with DOX. In addition, both doxorubicin and β-carotene were released much faster from PCL-based polymeric micelles. Dissipative particle dynamics (DPD) simulation revealed that the two drugs tended to aggregate in the core of the PCL-based micelles but disperse in the core of PLLA based micelles. In vitro cytotoxicity investigation of DOX loaded micelles demonstrated that a faster drug release warranted a more efficient cancer-killing effect. This research could serve as a guideline for the rational design of polymeric micelles for drug delivery.

  1. Enhancement of bioavailability by formulating rhEPO ionic complex with lysine into PEG-PLA micelle

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yanan; Sun, Fengying; Wang, Dan; Zhang, Renyu [Jilin University, College of Life Science (China); Dou, Changlin; Liu, Wanhui; Sun, Kaoxiang, E-mail: sunkx@ytu.edu.cn [Yantai University, School of Pharmacy (China); Li, Youxin, E-mail: liyouxin@jlu.edu.cn [Jilin University, College of Life Science (China)

    2013-10-15

    A composite micelle of ionic complex encapsulated into poly(ethylene glycol)-poly(d,l-lactide) (PEG-PLA) di-block copolymeric micelles was used for protein drug delivery to improve its pharmacokinetic performance. In this study, recombinant human erythropoietin (rhEPO, as a model protein) was formulated with lysine into composite micelles at a diameter of 71.5 nm with narrow polydispersity indices (PDIs < 0.3). Only a trace amount of protein was in aggregate form. The zeta potential of the spherical micelles was ranging from -0.54 to 1.39 mv, and encapsulation efficiency is high (80 %). The stability of rhEPO was improved significantly in composite micelles in vitro. Pharmacokinetic studies in rats showed significant, enhanced plasma retention of the composite micelles in comparison with native rhEPO. Areas under curve (AUCs) of the rhEPO released from the composite micelles were 4.5- and 2.3-folds higher than those of the native rhEPO and rhEPO-loaded PEG-PLA micelle, respectively. In addition, the composite micelles exhibited good biocompatibility using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay with human embryonic kidney (HEK293T) cells. All these features are preferable for utilizing the composite micelles as a novel protein delivery system.

  2. Gold nanorod in reverse micelles: a fitting fusion to catapult lipase activity.

    Science.gov (United States)

    Maiti, Subhabrata; Ghosh, Moumita; Das, Prasanta Kumar

    2011-09-21

    Lipase solubilized within gold nanorod doped CTAB reverse micelles exhibited remarkable improvement in its activity mainly due to the enhanced interfacial domain of newly developed self-assembled nanocomposites.

  3. THERMOSENSITIVE POLYION COMPLEX MICELLES PREPARED BY SELF-ASSEMBLY OF TWO OPPOSITELY CHARGED DIBLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Pan He; Chang-wen Zhao; Chun-sheng Xiao; Zhao-hui Tang; Xue-si Chen

    2013-01-01

    Polyion complex (PIC) micelles were spontaneously formed in aqueous solutions through electrostatic interaction between two oppositely charged block copolymers,poly(N-isopropylacrylamide)-b-poly(L-glutamic acid) and poly(N-isopropylacrylamide)-b-poly(L-lysine).Their controlled synthesis was achieved via the ring opening polymerization of N-carboxyanhydrides (NCA),ε-benzyloxycarbonyl-L-lysine (Lys(Z)-NCA) or γ-benzyl-L-glutamate (BLG-NCA) with amino-terminated poly(N-isopropylacrylamide) macroinitiator and the subsequent deprotection reaction.The formation of PIC micelles was confirmed by dynamic light scattering and transmission electron microscopy.Turbidimetric characterization suggested that the formed PIC micelles had a concentration-dependent thermosensitivity and their phase transition behaviors could be easily adjusted either by the block length of coplymers or the concentration of micelles.

  4. CD and 31P NMR studies of tachykinin and MSH neuropeptides in SDS and DPC micelles

    Science.gov (United States)

    Schneider, Sydney C.; Brown, Taylor C.; Gonzalez, Javier D.; Levonyak, Nicholas S.; Rush, Lydia A.; Cremeens, Matthew E.

    2016-02-01

    Secondary structural characteristics of substance P (SP), neurokinin A (NKA), neurokinin B (NKB), α-melanocyte stimulating hormone peptide (α-MSH), γ1-MSH, γ2-MSH, and melittin were evaluated with circular dichroism in phosphite buffer, DPC micelles, and SDS micelles. CD spectral properties of γ1-MSH and γ2-MSH as well as 31P NMR of DPC micelles with all the peptides are reported for the first time. Although, a trend in the neuropeptide/micelle CD data appears to show increased α-helix content for the tachykinin peptides (SP, NKA, NKB) and increased β-sheet content for the MSH peptides (α-MSH, γ1-MSH, γ2-MSH) with increasing peptide charge, the lack of perturbed 31P NMR signals for all neuropeptides could suggest that the reported antimicrobial activity of SP and α-MSH might not be related to a membrane disruption mode of action.

  5. Exploring Polymeric Micelles for Improved Delivery of Anticancer Agents: Recent Developments in Preclinical Studies

    Directory of Open Access Journals (Sweden)

    Wei Fan

    2013-03-01

    Full Text Available As versatile drug delivery systems, polymeric micelles have demonstrated particular strength in solubilizing hydrophobic anticancer drugs while eliminating the use of toxic organic solvents and surfactants. However, the true promise of polymeric micelles as drug carriers for cancer therapy resides in their potential ability to preferentially elevate drug exposure in the tumor and achieve enhanced anticancer efficacy, which still remains to be fully exploited. Here, we review various micellar constructs that exhibit the enhanced permeation and retention effect in the tumor, the targeting ligands that potentiate the anticancer efficacy of micellar drugs, and the polyplex micelle systems suitable for the delivery of plasmid DNA and small interference RNA. Together, these preclinical studies in animal models help us further explore polymeric micelles as emerging drug carriers for targeted cancer therapy.

  6. Removal of Cr(VI from Aqueous Environments Using Micelle-Clay Adsorption

    Directory of Open Access Journals (Sweden)

    Mohannad Qurie

    2013-01-01

    Full Text Available Removal of Cr(VI from aqueous solutions under different conditions was investigated using either clay (montmorillonite or micelle-clay complex, the last obtained by adsorbing critical micelle concentration of octadecyltrimethylammonium ions onto montmorillonite. Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI from aqueous solutions. Langmuir adsorption isotherm fitted the experimental data giving significant results. Filtration experiments using columns filled with micelle-clay complex mixed with sand were performed to assess Cr(VI removal efficiency under continuous flow at different pH values. The micelle-clay complex used in this study was capable of removing Cr(VI from aqueous solutions without any prior acidification of the sample. Results demonstrated that the removal effectiveness reached nearly 100% when using optimal conditions for both batch and continuous flow techniques.

  7. [Study on the backward extraction of cellulase in rhamnolipid reverse micelles].

    Science.gov (United States)

    Zhao, Yan-Ge; Yuan, Xing-Zhong; Huang, Hua-Jun; Cui, Kai-Long; Peng, Xin; Peng, Zi-Yuan; Zeng, Guang-Ming

    2014-02-01

    This paper studied the backward extraction of cellulase in RL/isooctane/n-hexanol reverse micelles system. Several key parameters influencing the backward extraction efficiency and activity recovery of cellulase were investigated, including stripping aqueous pH, stripping time, salt type and ionic strength, and addition of alcohols. The experiment results indicated that the optimal parameter values as follows: stripping aqueous pH 7.0, stripping time 30 min, 0.15 mol x L(-1) of KCl, dosage of n-butanol 2%. Under above optimum conditions, the backward extraction efficiency and activity recovery were up to 76.22% and 93.39%, respectively. The backward extraction of cellulase using reverse micelles based on biosurfactant RL performs well. Furthermore, RL has many advantages such as high biodegradability, low critical micelle concentration, etc. The application prospects of RL reverse micelles are extensive.

  8. New Strategies for Constructing Polymeric Micelles and Hollow Spheres Via Self-Assembly

    Institute of Scientific and Technical Information of China (English)

    Ming Jiang

    2005-01-01

    @@ 1Introduction In recent years, self-assembly of block copolymers leading to micelles in selective solvents, which dissolve only one of the blocks, has developed rapidly because the micelles are very strong candidates for potential applications in advanced technologies. The micelles usually have core-shell structure which are connected by covalent bonds. Based on our long-term research on interpolymer complexation due to hydrogen bonding, where we noticed that the complexation often led to the formation of irregular aggregates, we succeeded recently in developing a series of new approaches to polymeric micelles and hollow spheres via specific intermolecular interactions. As in these approaches, a variety of polymers with interacting groups i.e. homopolymers, random copolymers, graft copolymers as well as low mass compounds (LMC), can be used as building blocks, our research strategies have substantially extended the field of self-assembly.

  9. Effect of water on the local electric potential of simulated ionic micelles

    Energy Technology Data Exchange (ETDEWEB)

    Brodskaya, Elena N.; Vanin, Alexander A., E-mail: alexvanin@yandex.ru [Institute of Chemistry, St. Petersburg State University, Universitetskiy pr. 26, Petrodvoretz, St. Petersburg 198504 (Russian Federation)

    2015-07-28

    Ionic micelles in an aqueous solution containing single-charged counter-ions have been simulated by molecular dynamics. For both cationic and anionic micelles, it has been demonstrated that explicit description of solvent has strong effect on the micelle’s electric field. The sign of the local charge alters in the immediate vicinity of the micellar crown and the electric potential varies nonmonotonically. Two micelle models have been examined: the hybrid model with a rigid hydrocarbon core and the atomistic model. For three molecular models of water (Simple Point Charge model (SPC), Transferable Intermolecular Potential 5- Points (TIP5P) and two-centered S2), the results have been compared with those for the continuum solvent model. The orientational ordering of solvent molecules has strong effect on the local electric field surprisingly far from the micelle surface.

  10. Nanostructured oxygen sensor--using micelles to incorporate a hydrophobic platinum porphyrin.

    Directory of Open Access Journals (Sweden)

    Fengyu Su

    Full Text Available Hydrophobic platinum(II-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl-porphyrin (PtTFPP was physically incorporated into micelles formed from poly(ε-caprolactone-block-poly(ethylene glycol to enable the application of PtTFPP in aqueous solution. Micelles were characterized using dynamic light scattering (DLS and atomic force microscopy (AFM to show an average diameter of about 140 nm. PtTFPP showed higher quantum efficiency in micellar solution than in tetrahydrofuran (THF and dichloromethane (CH₂Cl₂. PtTFPP in micelles also exhibited higher photostability than that of PtTFPP suspended in water. PtTFPP in micelles exhibited good oxygen sensitivity and response time. This study provided an efficient approach to enable the application of hydrophobic oxygen sensors in a biological environment.

  11. Multifunctional targeting micelle nanocarriers with both imaging and therapeutic potential for bladder cancer

    Directory of Open Access Journals (Sweden)

    Lin TY

    2012-06-01

    Full Text Available Tzu-yin Lin,1 Hongyong Zhang,1 Juntao Luo,2,5 Yuanpei Li,2 Tingjuan Gao,3 Primo N Lara Jr,1,4,6 Ralph de Vere White,4 Kit S Lam,1,2 Chong-Xian Pan,1,3,61Division of Hematology and Oncology, Department of Internal Medicine, 2Department of Biochemistry and Molecular Medicine, 3NSF Center for Biophotonics Science and Technology, School of Medicine, 4Department of Urology, University of California-Davis, Sacramento, CA, 5Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, 6VA Northern California Health Care System, Mather, CA, USABackground: We previously developed a bladder cancer-specific ligand (PLZ4 that can specifically bind to both human and dog bladder cancer cells in vitro and in vivo. We have also developed a micelle nanocarrier drug-delivery system. Here, we assessed whether the targeting micelles decorated with PLZ4 on the surface could specifically target dog bladder cancer cells.Materials and methods: Micelle-building monomers (ie, telodendrimers were synthesized through conjugation of polyethylene glycol with a cholic acid cluster at one end and PLZ4 at the other, which then self-assembled in an aqueous solution to form micelles. Dog bladder cancer cell lines were used for in vitro and in vivo drug delivery studies.Results: Compared to nontargeting micelles, targeting PLZ4 micelles (23.2 ± 8.1 nm in diameter loaded with the imaging agent DiD and the chemotherapeutic drug paclitaxel or daunorubicin were more efficient in targeted drug delivery and more effective in cell killing in vitro. PLZ4 facilitated the uptake of micelles together with the cargo load into the target cells. We also developed an orthotopic invasive dog bladder cancer xenograft model in mice. In vivo studies with this model showed the targeting micelles were more efficient in targeted drug delivery than the free dye (14.3×; P < 0.01 and nontargeting micelles (1.5×; P < 0.05.Conclusion: Targeting micelles decorated with PLZ4 can selectively

  12. Bioreducible unimolecular micelles based on amphiphilic multiarm hyperbranched copolymers for triggered drug release

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel type of bioreducible amphiphilic multiarm hyperbranched copolymer (H40-star-PLA-SS-PEG) based on Boltorn H40 core,poly(L-lactide) (PLA) inner-shell,and poly(ethylene glycol) (PEG) outer-shell with disulfide-linkages between the hydrophobic and hydrophilic moieties was developed as unimolecular micelles for controlled drug release triggered by reduction.The obtained H40-star-PLA-SS-PEG was characterized in detail by nuclear magnetic resonance (NMR),Fourier transform infrared (FTIR),gel permeation chromatography (GPC),differential scanning calorimeter (DSC),and thermal gravimetric analysis (TGA).Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses suggested that H40-star-PLA-SS-PEG formed stable unimolecular micelles in aqueous solution with an average diameter of 19 nm.Interestingly,these micelles aggregated into large particles rapidly in response to 10 mM dithiothreitol (DTT),most likely due to shedding of the hydrophilic PEG outer-shell through reductive cleavage of the disulfide bonds.As a hydrophobic anticancer model drug,doxorubicin (DOX) was encapsulated into these reductive unimolecular micelles.In vitro release studies revealed that under the reduction-stimulus,the detachment of PEG outer-shell in DOX-loaded micelles resulted in a rapid drug release.Flow cytometry and confocal laser scanning microscopy (CLSM) measurements indicated that these DOX-loaded micelles were easily internalized by living cells.Methyl tetrazolium (MTT) assay demonstrated a markedly enhanced drug efficacy of DOX-loaded H40-star-PLA-SS-PEG micelles as compared to free DOX.All of these results show that these bioreducible unimolecular micelles are promising carriers for the triggered intracellular delivery of hydrophobic anticancer drugs.

  13. Micellar lipid composition affects micelle interaction with class B scavenger receptor extracellular loops.

    Science.gov (United States)

    Goncalves, Aurélie; Gontero, Brigitte; Nowicki, Marion; Margier, Marielle; Masset, Gabriel; Amiot, Marie-Josèphe; Reboul, Emmanuelle

    2015-06-01

    Scavenger receptors (SRs) like cluster determinant 36 (CD36) and SR class B type I (SR-BI) play a debated role in lipid transport across the intestinal brush border membrane. We used surface plasmon resonance to analyze real-time interactions between the extracellular protein loops and various ligands ranging from single lipid molecules to mixed micelles. Micelles mimicking physiological structures were necessary for optimal binding to both the extracellular loop of CD36 (lCD36) and the extracellular loop of SR-BI (lSR-BI). Cholesterol, phospholipid, and fatty acid micellar content significantly modulated micelle binding to and dissociation from the transporters. In particular, high phospholipid micellar concentrations inhibited micelle binding to both receptors (-53.8 and -74.4% binding at 0.32 mM compared with 0.04 mM for lCD36 and lSR-BI, respectively, P < 0.05). The presence of fatty acids was crucial for micelle interactions with both proteins (94.4 and 81.3% binding with oleic acid for lCD36 and lSR-BI, respectively, P < 0.05) and fatty acid type substitution within the micelles was the component that most impacted micelle binding to the transporters. These effects were partly due to subsequent modifications in micellar size and surface electric charge, and could be correlated to micellar vitamin D uptake by Caco-2 cells. Our findings show for the first time that micellar lipid composition and micellar properties are key factors governing micelle interactions with SRs.

  14. Improvement of in vivo efficacy of recombinant human erythropoietin by encapsulation in PEG–PLA micelle

    Directory of Open Access Journals (Sweden)

    Shi YN

    2012-12-01

    Full Text Available Yanan Shi,1,2,* Wan Huang,1,* Rongcai Liang,1–3 Kaoxiang Sun,2,3 Fangxi Zhang,2,3 Wanhui Liu,2,3 Youxin Li1–31College of Life Science, Jilin University, Changchun, China; 2State Key Laboratory of Long-acting and Targeting Drug Delivery System, Luye Pharmaceutical Co, Ltd, Yantai, China; 3School of Pharmacy, Yantai University, Yantai, China*These authors contributed equally to this workAbstract: To improve the pharmacokinetics and stability of recombinant human erythropoietin (rhEPO, rhEPO was successfully formulated into poly(ethylene glycol–poly(d,l-lactide (PEG–PLA di-block copolymeric micelles at diameters ranging from 60 to 200 nm with narrow polydispersity indices (PDIs; PDI < 0.3 and trace amount of protein aggregation. The zeta potential of the spherical micelles was in the range of −3.78 to 4.65 mV and the highest encapsulation efficiency of rhEPO in the PEG–PLA micelles was about 80%. In vitro release profiles indicated that the stability of rhEPO in the micelles was improved significantly and only a trace amount of aggregate was found. Pharmacokinetic studies in rats showed highly enhanced plasma retention time of the rhEPO-loaded PEG-PLA micelles in comparison with the native rhEPO group. Increased hemoglobin concentrations were also found in the rat study. Native polyacrylamide gel electrophoresis results demonstrated that rhEPO was successfully encapsulated into the micelles, which was stable in phosphate buffered saline with different pHs and concentrations of NaCl. Therefore, PEG–PLA micelles can be a potential protein drug delivery system.Keywords: rhEPO, PEG–PLA micelle, in vitro, pharmacokinetics, pharmacodynamics

  15. Multifunctional polymeric micelles for delivery of drugs and siRNA

    Directory of Open Access Journals (Sweden)

    Aditi M. Jhaveri

    2014-04-01

    Full Text Available Polymeric micelles, self-assembling nano-constructs of amphiphilic copolymers with a core-shell structure have been used as versatile carriers for delivery of drugs as well as nucleic acids. They have gained immense popularity owing to a host of favorable properties including their capacity to effectively solubilize a variety of poorly soluble pharmaceutical agents, biocompatibility, longevity, high stability in vitro and in vivo and the ability to accumulate in pathological areas with compromised vasculature. Moreover, additional functions can be imparted to these micelles by engineering their surface with various ligands and cell-penetrating moieties to allow for specific targeting and intracellular accumulation, respectively, to load them with contrast agents to confer imaging capabilities, and incorporating stimuli-sensitive groups that allow drug release in response to small changes in the environment. Recently, there has been an increasing trend towards designing polymeric micelles which integrate a number of the above functions into a single carrier to give rise to smart, multifunctional polymeric micelles. Such multifunctional micelles can be envisaged as key to improving the efficacy of current treatments which have seen a steady increase not only in hydrophobic small molecules, but also in biologics including therapeutic genes, antibodies and small interfering RNA (siRNA. The purpose of this review is to highlight recent advances in the development of multifunctional polymeric micelles specifically for delivery of drugs and siRNA. In spite of the tremendous potential of siRNA, its translation into clinics has been a significant challenge because of physiological barriers to its effective delivery and the lack of safe, effective and clinically suitable vehicles. To that end, we also discuss the potential and suitability of multifunctional polymeric micelles, including lipid-based micelles, as promising vehicles for both siRNA and drugs.

  16. Multimodality CT/SPECT Evaluation of Micelle Drug Carriers for Treatment of Breast Tumors

    Science.gov (United States)

    2008-07-01

    TEM), dynamic light scattering (DLS), and NMR to examine morphology, size, and drug encapsulation . The in vitro efficacy of the micelles was then...be seen in Figure 2, β-lap PEG-PLA micelles were core-shell in nature, possessing a PEG hydrated layer on the surface, all the while encapsulating ...hydroxypropyl-β- cyclodextrin (HPβ-CD). However, the clinical trials show that a large number of patients suffer from high levels of hemolysis and anemia

  17. Corrosion Performance of Carbon Steel in Simulated Pore Solution in the Presence of Micelles

    OpenAIRE

    Hu, J; Koleva, D. A.; Wit, J.H.W. de; Kolev, H.; Breugel, K. van

    2011-01-01

    This study presents the results on the investigation of the corrosion behavior of carbon steel in model alkaline medium in the presence of very low concentration of polymeric nanoaggregates [0.0024 wt % polyethylene oxide (PEO)113-b-PS70 micelles]. The steel electrodes were investigated in chloride free and chloride-containing cement extracts. The electrochemical measurements (electrochemical impedance spectroscopy and potentiodynamic polarization) indicate that the presence of micelles alter...

  18. Peptide crosslinked micelles: a new strategy for the design and synthesis of peptide vaccines

    OpenAIRE

    Hao, Jihua; Kwissa, Marcin; Pulendran, Bali; Murthy, Niren

    2006-01-01

    This report presents a new and simple methodology for the synthesis of multicomponent peptide vaccines, named the peptide crosslinked micelles (PCMs). The PCMs are core shell micelles designed to deliver peptide antigens and immunostimulatory DNA to antigen-presenting cells (APCs). They are composed of immunostimulatory DNA, peptide antigen, and a thiopyridal derived poly(ethylene glycol)-polylysine block copolymer. The peptide antigen acts as a crosslinker in the PCM strategy, which allows t...

  19. A 502-Base Free-Solution Electrophoretic DNA Sequencing Method Using End-Attached Wormlike Micelles.

    Science.gov (United States)

    Istivan, Stephen B; Bishop, Daniel K; Jones, Angela L; Grosser, Shane T; Schneider, James W

    2015-11-17

    We demonstrate that the use of wormlike nonionic micelles as drag-tags in end-labeled free-solution electrophoresis ("micelle-ELFSE") provides single-base resolution of Sanger sequencing products up to 502 bases in length, a nearly 2-fold improvement over reported ELFSE separations. "CiEj" running buffers containing 48 mM C12E5, 6 mM C10E5, and 3 M urea (32.5 °C) form wormlike micelles that provide a drag equivalent to an uncharged DNA fragment with a length (α) of 509 bases (effective Rh = 27 nm). Runtime in a 40 cm capillary (30 kV) was 35 min for elution of all products down to the 26-base primer. We also show that smaller Triton X-100 micelles give a read length of 103 bases in a 4 min run, so that a combined analysis of the Sanger products using the two buffers in separate capillaries could be completed in 14 min for the full range of lengths. A van Deemter analysis shows that resolution is limited by diffusion-based peak broadening and wall adsorption. Effects of drag-tag polydispersity are not observed, despite the inherent polydispersity of the wormlike micelles. We ascribe this to a stochastic size-sampling process that occurs as micelle size fluctuates rapidly during the runtime. A theoretical model of the process suggests that fluctuations occur with a time scale less than 10 ms, consistent with the monomer exchange process in nonionic micelles. The CiEj buffer has a low viscosity (2.7 cP) and appears to be semidilute in micelle concentration. The large drag-tag size of the CiEj buffers leads to steric segregation of the DNA and tag for short fragments and attendant mobility shifts.

  20. [Sodium and hypertension].

    Science.gov (United States)

    de Wardener, H E

    1996-09-01

    Over several million years the human race was programmed to eat a diet which contained about 15 mmol of sodium (1 g of sodium chloride) per day. It is only five to ten thousand years ago that we became addicted to salt. Today we eat about 150 mmol of sodium (9-12 g of salt) per day. It is now apparent that this sudden rise in sodium intake (in evolutionary terms) is the most likely cause for the rise in blood pressure with age that occurs in the majority of the world's population. Those which consume less than 60 mmol/day do not develop hypertension. The reason for the rise in sodium intake is not known but it is probable that an important stimulus was the discovery that meat could be preserved by immersion into a concentrated salt solution. This seemingly miraculous power endowed salt with such magical and medicinal qualities that it became a symbol of goodness and health. It was not until 1904 Ambard and Beaujard suggested that on the contrary dietary salt could be harmful and raise the blood pressure. At first the idea did not prosper and it continues to be opposed by a diminishing band. The accumulated evidence that sodium intake is related to the blood pressure in normal man and animals and in inherited forms of hypertension has been obtained from experimental manipulations and studies of human populations. The following observation links sodium and hypertension. An increase in sodium intakes raises the blood pressure of the normal rat, dog, rabbit, baboon, chimpanzee and man. Population studies have demonstrated a significant correlation between sodium intake and the customary rise in blood pressure with age. The development of hypertensive strains of rats has revealed that the primary genetic lesion which gives rise to hypertension resides in the kidney where it impairs the urinary excretion of sodium. There is similar but less convincing evidence in essential hypertension. The kidney in both essential hypertension and hypertensive strains of rats share a

  1. A study on organized assemblies in the sodium alkylcarboxylate/ fatty alcohol/water systems

    Institute of Scientific and Technical Information of China (English)

    MAO, Mina; FU, Hong-Lanb; ZHU, Bu-Yaoa; HE, Xua; SHI, Hong-Taoa; HUANG, Jian-Bin

    2000-01-01

    The phase behavior and evolution of self-organized assembling sttructures in the sodium allkylcarboxylate/fatty alcohol systems were investigated by TEM. With increasing concentration of fatty alcohd, the micelles transform into lamellar- La phase, sponge L3 phase, multilamellar vesicle, and transform back to lamellar La phase. At higher alcohol concentration, a stable two aqueous phase coexisting region has been observed in this kind of systems after aged two months. Unilamellar vesicles were found both in two separated phases but the vesicle densi ty ofthe upper phase is much higher than that of the bottom phase.

  2. Micelle Enhanced Fluorimetric and Thin Layer Chromatography Densitometric Methods for the Determination of (± Citalopram and its S – Enantiomer Escitalopram

    Directory of Open Access Journals (Sweden)

    Elham A. Taha

    2009-01-01

    Full Text Available Two sensitive and validated methods were developed for determination of a racemic mixture citalopram and its enantiomer S-(+ escitalopram. The first method was based on direct measurement of the intrinsic fluorescence of escitalopram using sodium dodecyl sulfate as micelle enhancer. This was further applied to determine escitalopram in spiked human plasma, as well as in the presence of common and co-administerated drugs. The second method was TLC densitometric based on various chiral selectors was investigated. The optimum TLC conditions were found to be sensitive and selective for identification and quantitative determination of enantiomeric purity of escitalopram in drug substance and drug products. The method can be useful to investigate adulteration of pure isomer with the cheap racemic form.

  3. Hydrolytic cleavage of bis(-nitrophenyl) phosphate by Schiff base MnIII complexes containing morpholine pendants in Gemini 16-6-16 micelles

    Indian Academy of Sciences (India)

    Weidong Jiang; Bin Xu; Junbo Zhong; Jianzhang Li; Fuan Liu

    2008-07-01

    Catalytic efficiency of two Schiff base manganese(III) complexes toward the hydrolysis of bis(-nitrophenyl) phosphate (BNPP) was evaluated in a micellar media formed by bis(hexadecyldimethylammonium) hexane bromide (abbr.16-6-16, 2Br-) at 25°C. Effects of various reaction conditions on the hydrolysis of BNPP were systematically investigated. The observations obtained indicate that the two Mn(III) catalysts can efficiently promote hydrolysis of BNPP with a six order of magnitude rate enhancement relative to the background rate constant (k0). Different structures of the two complexes lend to their distinguishing activities each other. Furthermore, rates of BNPP hydrolysis in Gemini 16-6-16 micellar medium are much higher than that in hexadecyltrimethylammonium bromide (CTAB) and -lauroylsarcosine sodium (LSS) micelles.

  4. Covalent attachment of mechanoresponsive luminescent micelles to glasses and polymers in aqueous conditions.

    Science.gov (United States)

    Sagara, Yoshimitsu; Komatsu, Toru; Ueno, Tasuku; Hanaoka, Kenjiro; Kato, Takashi; Nagano, Tetsuo

    2014-03-19

    Covalent attachment of mechanoresponsive luminescent organic or organometallic compounds to other materials is a promising approach to develop a wide variety of mechanoresponsive luminescent materials. Here, we report covalently linkable mechanoresponsive micelles that change their photoluminescence from yellow to green in response to mechanical stimulation under aqueous conditions. These micelles are composed of a dumbbell-shaped amphiphilic pyrene derivative having amine groups at the peripheral positions of its dendrons. Using a well-established cross-linker, the micelles were covalently linked via their peripheral amine groups to the surface of glass beads, polylactic acid (PLA) beads, and living cells under aqueous conditions. Vortexing of glass beads bearing the micelles in a glass vial filled with water caused a photoluminescence color change from yellow to green. PLA beads bearing the micelles showed no change in photoluminescence color under the same conditions. We ascribe this result to the lower density and stiffness of the PLA beads, because the color of the PLA beads changed on vortexing in the presence of bare glass beads. HeLa cells and HL-60 cells bearing the micelles showed no obvious photoluminescence color change under vortexing. The structure, photophysical properties, and mechanism of photoluminescence color change of the micellar assemblies were examined.

  5. Binary-component micelle and vesicle: Free energy and asymmetric distributions of amphiphiles between vesicle monolayers

    Institute of Scientific and Technical Information of China (English)

    Zhang Qi-Yi; Xiang Xun

    2013-01-01

    The real-space two-dimensional self-consistent field theory (SCFT) is employed to study the free energies of micelles and vesicles constituted by binary amphiphilic diblock copolymer AB in homopolymer A.With an increasing volume fraction of copolymer AB,there are morphological transitions from circle micelles to oblate circle-like micelles,to a compound structure with inverted micelles in the inner center and micelles outer layer,and to vesicles.Special attention is paid to the role of the copolymer AB in controlling the free energies of the micelles and vesicles by examining the effect of the length ratio of A/B with the fixed whole chain length of the AB copolymer,the length effect of A or B block with the corresponding fixed length of B or A block,for one component of copolymer,and the effect of different amphiphile compositions for a binary-component copolymer system.The quantity η is provided to describe the asymmetric density distribution of amphiphiles between the inner and outer monolayers of vesicles,and to quantify the relative asymmetric extent of the density distribution between two species of copolymers in binary component vesicles.

  6. Magnetothermally responsive star-block copolymeric micelles for controlled drug delivery and enhanced thermo-chemotherapy.

    Science.gov (United States)

    Deng, Li; Ren, Jie; Li, Jianbo; Leng, Junzhao; Qu, Yang; Lin, Chao; Shi, Donglu

    2015-06-07

    Magnetothermally responsive drug-loaded micelles were designed and prepared for cancer therapy. These specially designed micelles are composed of the thermo-responsive star-block copolymer poly(ε-caprolactone)-block-poly(2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene glycol)methacrylate) and Mn, Zn doped ferrite magnetic nanoparticles (MZF-MNPs). The thermo-responses of 6sPCL-b-P(MEO2MA-co-OEGMA) copolymers were shown to be dependent on the MEO2MA to OEGMA ratio. The lower critical solution temperature (LCST) of the star-block copolymers was controlled at 43 °C by adjusting the feed molar ratios of MEO2MA/OEGMA at 92 : 8. With the anti-tumor drug doxorubicin (DOX) self-assembling into the carrier system, the thermo-responsive micelles exhibited excellent temperature-triggered drug release behavior. In vitro cytotoxicity results showed high biocompatibility of the polymer micelles. Efficient cellular proliferation inhibition by the drug-loaded micelles was found on the HepG2 cells under different treatments. The thermo-responsive polymer micelles are promising for controlled drug delivery in tumor therapy under an alternating magnetic field.

  7. Cross-linked self-assembled micelle based nanosensor for intracellular pH measurements

    DEFF Research Database (Denmark)

    Ek, Pramod Kumar; Søndergaard, Rikke Vicki; Windschiegl, Barbara

    2014-01-01

    A micelle based nanosensor was synthesized and investigated as a ratiometric pH sensor for use in measurements in living cells by fluorescent microscopy. The nanosensor synthesis was based on self-assembly of an amphiphilic triblock copolymer, which was chemically cross-linked after micelle forma...... provided a sensor with a very broad measurement range that seems to be influenced by the chemical design of the sensor. Cell experiments show that the sensor is capable of monitoring the pH distributions in HeLa cells.......A micelle based nanosensor was synthesized and investigated as a ratiometric pH sensor for use in measurements in living cells by fluorescent microscopy. The nanosensor synthesis was based on self-assembly of an amphiphilic triblock copolymer, which was chemically cross-linked after micelle...... formation. The copolymer, poly(ethylene glycol)-b-poly(2-aminoethyl methacrylate)-b-poly(styrene) (PEG-b-PAEMA-b-PS), was synthesized by isolated macroinitiator atom transfer radical polymerization that forms micelles spontaneously in water. The PAEMA shell of the micelle was hereafter cross...

  8. [Construction of biotin-modified polymeric micelles for pancreatic cancer targeted photodynamic therapy].

    Science.gov (United States)

    Deng, Chun-yue; Long, Ying-ying; Liu, Sha; Chen, Zhang-bao; Li, Chong

    2015-08-01

    In this study, we explored the feasibility of biotin-mediated modified polymeric micelles for pancreatic cancer targeted photodynamic therapy. Poly (ethylene glycol)-distearoyl phosphatidyl ethanolamine (mPEG2000-DSPE) served as the drug-loaded material, biotin-poly(ethylene glycol)-distearoyl phosphatidyl ethanolamine (Biotin-PEG3400-DSPE) as the functional material and the polymeric micelles were prepared by a thin-film hydration method. The targeting capability of micelles was investigated by cell uptake assay in vitro and fluorescence imaging in vivo and the amounts of Biotin-PEG-DSPE were optimized accordingly. Hypocrellin B (HB), a novel photosensitizer was then encapsulated in biotinylated polymeric micelles and the anti-tumor efficacy was evaluated systemically in vitro and in vivo. The results showed that micelles with 5 mol % Biotin-PEG-DSPE demonstrated the best targeting capability than those with 20 mol % or 0.5 mol % of corresponding materials. This formulation has a small particle size [mean diameter of (36.74 ± 2.16) nm] with a homogeneous distribution and high encapsulation efficiency (80.06 ± 0.19) %. The following pharmacodynamics assays showed that the biotinylated micelles significantly enhanced the cytotoxicity of HB against tumor cells in vitro and inhibited tumor growth in vivo, suggesting a promising potential of this formulation for treatment of pancreatic cancer, especially those poorly permeable, or insensitive to radiotherapy and chemotherapy.

  9. PCP copolymers grafted with RGD enhance the rates of RGD-PCP micelles internalized into cells.

    Science.gov (United States)

    Chung, Tze-Wen; Tyan, Yu-Chang; Yang, Jean-Dean

    2010-01-01

    RGD-PCP copolymers were fabricated by grafting Arg-Gly-Asp (RGD) peptide to poly(epsilon-caprolactone)-b-chitooligosaccharide-b-poly(ethylene glycol) (PCP) copolymers and the rate of internalization of RGD-PCP micelles by PC 12 cells were examined. Increasing intensity of the absorbance of amine groups in FT-IR spectra of RGD-PCP copolymers compared with those of PCP copolymers indicated the presence of RGD in new copolymers. Moreover, the grafting efficiency and molar ratio of RGD peptides to PCP copolymers were 88.2% and 0.45, respectively, analysed with HPLC. The RGD-PCP copolymers self-assemble to micelles at the critical micelle concentration (CMC) of 0.018 wt% (178 mg L(-1)) and with a mean diameter of 90 nm using a dynamic light-scattering (DLS) analyser. Interestingly, the internalization of DPH-loaded RGD-PCP micelles into PC 12 cells is much faster (e.g. within 5 min) than that of PCP micelles. The new RGD-PCP micelles may potentially be used in cellular drug delivery.

  10. 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.

  11. Physical characterization and antioxidant activity of thymol solubilized Tween 80 micelles

    Science.gov (United States)

    Deng, Ling-Li; Taxipalati, Maierhaba; Que, Fei; Zhang, Hui

    2016-12-01

    Attempts were made to solubilize thymol in Tween 80 micelle to study the solubilization mechanism of thymol and the effect of solubilization on its antioxidant activity. The maximum solubilized concentration of thymol in a 2.0% (w/v) Tween 80 micelle solution is 0.2 wt%. There was no significant difference in Z-average diameter between the empty micelles and thymol solubilized micelles. 1H NMR spectra indicated that 3-H and 4-H on the benzene ring of thymol interacted with the ester group between the hydrophilic head group and the hydrophobic tail group of Tween 80 by Van der Waals’ force. Ferric reducing antioxidant potential (FRAP) and cupric ion reducing antioxidant capacity (CUPRAC) assays showed that the reducing antioxidant activity of free thymol did not change after solubilized in Tween 80 micelles. Compared to free thymol, the solubilized thymol showed higher activities to scavenge DPPH (2,2-diphenyl-1-picrylhydrazyl) and hydroxyl radicals. The present study suggested a possible preparation of thymol-carrying micelles with enhanced antioxidant activities that could be applied in food beverages.

  12. Complete regression of xenograft tumors using biodegradable mPEG-PLA-SN38 block copolymer micelles.

    Science.gov (United States)

    Lu, Lu; Zheng, Yan; Weng, Shuqiang; Zhu, Wenwei; Chen, Jinhong; Zhang, Xiaomin; Lee, Robert J; Yu, Bo; Jia, Huliang; Qin, Lunxiu

    2016-06-01

    7-Ethyl-10-hydroxy-comptothecin (SN38) is an active metabolite of irinotecan (CPT-11) and the clinical application of SN38 is limited by its hydrophobicity and instability. To address these issues, a series of novel amphiphilic mPEG-PLA-SN38-conjugates were synthesized by linking SN38 to mPEG-PLA-SA, and they could form micelles by self-assembly. The effects of mPEG-PLA composition were studied in vitro and in vivo. The mean diameters of mPEG2K-PLA-SN38 micelles and mPEG4K-PLA-SN38 micelles were 10-20nm and 120nm, respectively, and mPEG2K-PLA-SN38 micelles showed greater antitumor efficacy than mPEG4K-PLA-SN38 micelles both in vitro and in vivo. These data suggest that the lengths of mPEG and PLA chains had a major impact on the physicochemical characteristics and antitumor activity of SN38-conjugate micelles.

  13. New shell crosslinked micelles from dextran with hydrophobic end groups and their interaction with bioactive molecules.

    Science.gov (United States)

    Mocanu, Georgeta; Nichifor, Marieta; Stanciu, Magdalena C

    2015-03-30

    Micelles formed in aqueous solution by dextran with hydrophobic (alkyl) end-groups were stabilized through divinyl sulfone crosslinking of the dextran shell. The efficacy of the crosslinking reaction was influenced by the divinyl sulfone amount, the pH and micelle concentration. Crosslinked micelles with a moderate crosslinking degree were further functionalized by attachment of 10 and 17 moles% N-(2-hydroxypropyl)-N,N-dimethyl-N-benzylammonium chloride groups along the dextran chain. The size and shape of both crosslinked micelles and their cationic derivatives were analyzed by DLS and TEM. The prepared micelles were able to bind anionic diclofenac (60-370 mg/g), hydrophobic anionic indometacin (70-120 mg/g), and hydrophobic alpha-tocopherol (170-220 mg/g) or ergocalciferol (90-110 mg/g) by hydrophobic or/and electrostatic forces. The release experiments and the antioxidant activity of bound alpha-tocopherol highlighted the potential of the new nano-sized micelles mainly as carriers for prolonged and controlled delivery of hydrophobic drugs.

  14. Bending energetics of tablet-shaped micelles: a novel approach to rationalize micellar systems.

    Science.gov (United States)

    Bergström, L Magnus

    2007-02-19

    A novel approach to rationalize micellar systems is expounded in which the structural behavior of tablet-shaped micelles is theoretically investigated as a function of the three bending elasticity constants: spontaneous curvature (H0), bending rigidity (k(c)), and saddle-splay constant (k(c)). As a result, experimentally accessible micellar properties, such as aggregation number, length-to-width ratio, and polydispersity, may be related to the different bending elasticity constants. It is demonstrated that discrete micelles or connected cylinders form when H0 > 1/4xi, where xi is the thickness of a surfactant monolayer, whereas various bilayer structures are expected to predominate when H0 bending rigidity is lowered, approaching the critical point at k(c) = 0, whereas monodisperse globular micelles (small length-to-width ratio) are expected to be present at large k(c) values. The spontaneous curvature mainly determines the width of tablet-shaped or ribbonlike micelles, or the radius of disklike micelles, whereas the saddle-splay constant primarily influences the size but not the shape of the micelles.

  15. Reserch on backward extraction of soy protein by differentreverse micelle systems%不同反胶束体系萃取大豆蛋白研究

    Institute of Scientific and Technical Information of China (English)

    杨光胜; 陈复生; 张丽芬; 布冠好; 刘昆仑

    2014-01-01

    利用 AOT/异辛烷/KCl 溶液,SDS/异辛烷-正辛醇/KCL 溶液,CTAB/异辛烷-正辛醇/KCL 溶液三种反胶束体系前萃取大豆蛋白质,针对影响大豆蛋白萃取率的各种因素如 W0、缓冲溶液 pH、萃取温度、萃取时间、离子强度进行了研究,得到了三种反胶束前萃取的最佳工艺:W0均取16;缓冲溶液 pH 分别为6.5、6.5、10;萃取温度分别为45、45、35℃;萃取时间均取30 min;离子强度均取0.05 mol/L。试验结果表明 AOT 和 SDS 反胶束最佳前萃取条件相同,CTAB 反胶束最佳前萃条件中 pH 和萃取温度与以上两种体系不同,其它条件相同。%Sulphosuccinic acid bis(2-ethylhexyl)estersodium salt(AOT),isooctane and KCl solution reverse micelle system,sodium dodecyl sulfate(SDS)/isooctane /n-octyl alcohol and KCl solution reverse micelle system and cetyltrimethyl ammonium bromide(CTAB)/isooctane-heptylane capryl alcohol/KCl buffer solution revese micelle system were used to backward extract soy protein. The effects of W0,pH,temperature,time,ionic strength were analyzed and the optimal conditions were obtained:W 0=16;pH=6.5、6.5、10;temperature=45 ℃、45 ℃、35 ℃ ;time=30 min;ionic strength=0.05 mol/L. The experimental results showed that the highest forward extraction conditions of SDS and AOT reverse micelle were the same,the pH and temperature of CTAB highest forward extraction conditions were different from the above two systems.

  16. Methodology for Extraction of Remaining Sodium of Used Sodium Containers

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Minhwan; Kim, Jongman; Cho, Youngil; Jeong, Jiyoung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Sodium used as a coolant in the SFR (Sodium-cooled Fast Reactor) reacts easily with most elements due to its high reactivity. If sodium at high temperature leaks outside of a system boundary and makes contact with oxygen, it starts to burn and toxic aerosols are produced. In addition, it generates flammable hydrogen gas through a reaction with water. Hydrogen gas can be explosive within the range of 4.75 vol%. Therefore, the sodium should be handled carefully in accordance with standard procedures even though there is a small amount of target sodium remainings inside the containers and drums used for experiment. After the experiment, all sodium experimental apparatuses should be dismantled carefully through a series of draining, residual sodium extraction, and cleaning if they are no longer reused. In this work, a system for the extraction of the remaining sodium of used sodium drums has been developed and an operation procedure for the system has been established. In this work, a methodology for the extraction of remaining sodium out of the used sodium container has been developed as one of the sodium facility maintenance works. The sodium extraction system for remaining sodium of the used drums was designed and tested successfully. This work will contribute to an establishment of sodium handling technology for PGSFR. (Prototype Gen-IV Sodium-cooled Fast Reactor)

  17. A conductometric investigation of hydroxypropylmethyl cellulose/sodium dodecyl sulfate/nonionic surfactant systems

    Directory of Open Access Journals (Sweden)

    Petrović Lidija B.

    2014-01-01

    Full Text Available Surfactant mixtures are very often used in various cosmetic and pharmaceutical products because they commonly act in synergism and provide more favorable properties than the single surfactants. At the same time, the 9 presence of polymers in mixtures of surfactants may lead to molecular interactions thereby affecting product stability and activity. For these reasons it is very important to determine the surfactant interactions influence on 1micellization and mixed micellization, as well as polymer-surfactants mixed micelles interactions. In this work we examined self-aggregation of nonionic surfactants, polysorbate 20 (Tween 20, polyoxyethylene octylphenyl ether (Triton X100 and polyoxyethylene-polyoxypropylene block copolymer (Pluronic F68 with ionic surfactant, sodium dodecylsulfate, in aqueous solution at 40ºC using conductometric titration method. It was found that concentration region for mixed micelle formation depends on nonionic surfactant characteristics and its concentration. Formation of surfactants mixed micelles in the presence of nonionic polymer, hydroxypropylmethyl cellulose, and their binding to polymer hydrophobic sites, were investigated too. Analysis of obtained results points to different kinds of interactions in investigated systems, which are crucial for their application. [Projekat Ministarstva nauke Republike Srbije, br. III 46010

  18. 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.

  19. Sodium urine test

    Science.gov (United States)

    ... urine sodium level may be a sign of: Adrenal glands releasing too much hormone ( hyperaldosteronism ) Not enough fluid in the body (dehydration) Diarrhea and fluid loss Heart failure Kidney problems, such as chronic kidney disease or ...

  20. Brain-targeting study of stearic acid–grafted chitosan micelle drug-delivery system

    Directory of Open Access Journals (Sweden)

    Xie YT

    2012-06-01

    Full Text Available Yi-Ting Xie, Yong-Zhong Du, Hong Yuan, Fu-Qiang HuCollege of Pharmaceutical Sciences, Zhejiang University, Hangzhou, ChinaPurpose: Therapy for central nervous system disease is mainly restricted by the blood–brain barrier. A drug-delivery system is an effective approach to overcome this barrier. In this research, the potential of polymeric micelles for brain-targeting drug delivery was studied.Methods: Stearic acid–grafted chitosan (CS-SA was synthesized by hydrophobic modification of chitosan with stearic acid. The physicochemical characteristics of CS-SA micelles were investigated. bEnd.3 cells were chosen as model cells to evaluate the internalization ability and cytotoxicity of CS-SA micelles in vitro. Doxorubicin (DOX, as a model drug, was physically encapsulated in CS-SA micelles. The in vivo brain-targeting ability of CS-SA micelles was qualitatively and quantitatively studied by in vivo imaging and high-performance liquid chromatography analysis, respectively. The therapeutic effect of DOX-loaded micelles in vitro was performed on glioma C6 cells.Results: The critical micelle concentration of CS-SA micelles with 26.9% ± 1.08% amino substitute degree was 65 µg/mL. The diameter and surface potential of synthesized CS-SA micelles in aqueous solution was 22 ± 0.98 nm and 36.4 ± 0.71 mV, respectively. CS-SA micelles presented excellent cellular uptake ability on bEnd.3 cells, the IC50 of which was 237.6 ± 6.61 µg/mL. DOX-loaded micelles exhibited slow drug-release behavior, with a cumulative release up to 72% within 48 hours in vitro. The cytotoxicity of DOX-loaded CS-SA micelles against C6 was 2.664 ± 0.036 µg/mL, compared with 0.181 ± 0.066 µg/mL of DOX • HCl. In vivo imaging results indicated that CS-SA was able to transport rapidly across the blood–brain barrier and into the brain. A maximum DOX distribution in brain of 1.01%/g was observed 15 minutes after administration and maintained above 0.45%/g within 1 hour

  1. 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...... have analysed the scattering data in the entire regime of scattering vectors that are relevant for determining the structure of the micelles. Our obtained results for pure surfactant micelles, as well as those of mixed catanionic micelles presented in a recent study, show somewhat unexpectedly...... 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...

  2. Investigation of thermo-sensitive amphiphilic micelles as drug carriers for chemotherapy in cholangiocarcinoma in vitro and in vivo.

    Science.gov (United States)

    Wang, Xuefeng; Li, Songgang; Wan, Ziwei; Quan, Zhiwei; Tan, Qinggang

    2014-03-10

    Cholangiocarcinoma is an epithelial cancer of the bile ducts with poor prognosis and, in recent years, a rapidly increasing incidence. In this study, nano-sized thermo-sensitive micelles were investigated as drug carriers to improve chemotherapy in cholangiocarcinoma. Thermo-sensitive amphiphilic block copolymer, P-(N,N-isopropylacrylamide-co-N-hydroxymethylacrylamide)-b-caprolactone [P-(NIPAAm-co-NHMAAm)-b-PCL] with lower critical solution temperature (LCST) at about 38°C was synthesized. Doxorubicin (DOX)-loaded micelles were prepared by dialysis method. The micelles exhibited a sustained and temperature-dependent DOX release. Toxicity of the blank micelles for human cholangiocarcinoma (QBC939) cells was minimal both in vitro and in vivo. In contrast, the DOX-loaded micelles effectively inhibited proliferation and induced apoptosis of QBC939 cells in vitro (pthermo-sensitive amphiphilic micelles are a promising and effective drug carrier, and show potential for improving chemotherapy for cholangiocarcinoma.

  3. Adsorption behavior of pH-dependent phytic acid micelles at the copper surface observed by Raman and electrochemistry

    Science.gov (United States)

    Shen, Shu; Du, Juan; Guo, Xiao-yu; Wen, Ying; Yang, Hai-Feng

    2015-02-01

    As heated at 90 °C, phytic acid (PA) molecules in the solution self-organized to form the PA micelles. The size of PA micelles could be tuned by varying pH of the solutions. The adsorption behavior of the different micelles at the copper surface and their corrosion inhibition mechanisms in 0.5 M H2SO4 solution were studied by using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and surface-enhanced Raman scattering (SERS) spectroscopy. Raman studies showed that the bigger micelles anchoring on the copper surface via P27sbnd O28, P43sbnd O42 and P35sbnd O36 groups, while the smaller PA micelles formed at pH 9 adsorbed at the surface through P35sbnd O36 group. The electrochemical measurements demonstrated that the copper modified with the smaller micelles presented the best inhibition efficiency in 0.5 M H2SO4 solution.

  4. Skeletal muscle sodium channelopathies.

    Science.gov (United States)

    Nicole, Sophie; Fontaine, Bertrand

    2015-10-01

    This is an update on skeletal muscle sodium channelopathies since knowledge in the field have dramatically increased in the past years. The relationship between two phenotypes and SCN4A has been confirmed with additional cases that remain extremely rare: severe neonatal episodic laryngospasm mimicking encephalopathy, which should be actively searched for since patients respond well to sodium channel blockers; congenital myasthenic syndromes, which have the particularity to be the first recessive Nav1.4 channelopathy. Deep DNA sequencing suggests the contribution of other ion channels in the clinical expressivity of sodium channelopathies, which may be one of the factors modulating the latter. The increased knowledge of channel molecular structure, the quantity of sodium channel blockers, and the availability of preclinical models would permit a most personalized choice of medication for patients suffering from these debilitating neuromuscular diseases. Advances in the understanding of the molecular structure of voltage-gated sodium channels, as well as availability of preclinical models, would lead to improved medical care of patients suffering from skeletal muscle, as well as other sodium channelopathies.

  5. 硫酸存在时N-溴代苯二甲酰亚胺对甘露糖的胶束催化氧化%Micelle Catalyzed Oxidation of Mannose by N-Bromophthalimide in the Presence of Sulfuric Acid

    Institute of Scientific and Technical Information of China (English)

    KATRE Yokraj; SINGH Minu; PATIL Sangeeta; SINGH Ajaya K

    2009-01-01

    The kinetics of micellar-catalyzed oxidation of mannose by N-bromophthalimide was studied in the presence of sulfuric acid at 313 K. The orders of reaction with respect to [mannose], [oxidant], and [H+] were found to be fractional, first, and negative fractional order, respectively. Anionic micelles of sodium dodecyl sulfate showed a partial inhibitory effect, while cationic micelles of cetyltrimethylammonium bromide increased the reaction rate with the same kinetic behavior. The reaction was catalyzed by cationic micelles, because of favorable electrostatic/thermodynamic/ hydrophobic/hydrogen bonding between reactants and cationic micelles. Their catalytic roles are best explained by Berezin's model. A variation of [phthalimide] showed that the rate of reaction decreased with increasing [phthalimide]. It was observed that, an increase of [mercuric acetate] had no effect on reaction velocity. The influence of salts on the reaction rate was also studied. The rate constant (kw), binding constants (Ks+Ko), and corresponding activation parameters (Ea, △H#, △S#, and △G#) were determined. A detailed mechanism with associated reaction kinetics is presented and discussed.

  6. Study on Osmotic Pressure and Liquid-Liquid Equilibria for Micelle, Colloid and Microemulsion Systems by Yukawa Potential

    Institute of Scientific and Technical Information of China (English)

    FU,Dong(付东); LU,Jiu-Fang(陆九芳); WU,Wei(吴畏); Li,Yi-Gui(李以圭)

    2004-01-01

    An equation of state (EOS) was established to study the osmotic pressure and liquid-liquid equilibria for micelle,colloid and microemulsion systems. The Carnahan-Starling equation was used for the hard sphere repulsion. The Yukawa potential was used to describe both the attractive dispersion and the double-layer repulsion. By using the established EOS, the osmotic pressures for charged colloid, uncharged micelle, uncharged and weakly charged microemuslion, the phase equilibria for uncharged micelle and charged colloid systems were studied.

  7. Drug-loaded pseudo-block copolymer micelles with a multi-armed star polymer as the micellar exterior

    Science.gov (United States)

    Xie, Chen; Zhang, Peng; Zhang, Zhengkui; Yang, Chenchen; Zhang, Jialiang; Wu, Wei; Jiang, Xiqun

    2015-07-01

    Supramolecular constructed pseudo block copolymer micelles based on β-cyclodextrin terminated 4 and 7 armed star poly(N-vinylpyrrolidone) and adamantane terminated linear poly(ε-caprolactone) were prepared. The size, morphology, stability and protein adsorption were experimentally examined. The micelles with 7 armed PVP chains as the micellar exterior showed the lowest amount of protein adsorption and the best stability in media. When cabazitaxel, a new taxane, was loaded into the micelles, 14.4% drug loading content and 85% encapsulation efficacy were achieved. In vitro cytotoxicity studies demonstrated that the cabazitaxel-loaded micelles show significant cytotoxicity against drug-resistant A2780/T cell lines. Biodistribution studies showed that the micelles can almost double the content of cargo in tumor sites compared with the free cargo. In vivo antitumor activity examinations indicated that cabazitaxel-loaded micelles show superior antitumor activity over free paclitaxel and free cabazitaxel.Supramolecular constructed pseudo block copolymer micelles based on β-cyclodextrin terminated 4 and 7 armed star poly(N-vinylpyrrolidone) and adamantane terminated linear poly(ε-caprolactone) were prepared. The size, morphology, stability and protein adsorption were experimentally examined. The micelles with 7 armed PVP chains as the micellar exterior showed the lowest amount of protein adsorption and the best stability in media. When cabazitaxel, a new taxane, was loaded into the micelles, 14.4% drug loading content and 85% encapsulation efficacy were achieved. In vitro cytotoxicity studies demonstrated that the cabazitaxel-loaded micelles show significant cytotoxicity against drug-resistant A2780/T cell lines. Biodistribution studies showed that the micelles can almost double the content of cargo in tumor sites compared with the free cargo. In vivo antitumor activity examinations indicated that cabazitaxel-loaded micelles show superior antitumor activity over free

  8. Enhanced solubilization and desorption of organochlorine pesticides (OCPs) from soil by oil-swollen micelles formed with a nonionic surfactant.

    Science.gov (United States)

    Zheng, Guanyu; Selvam, Ammaiyappan; Wong, Jonathan W C

    2012-11-06

    The effect of oil-swollen micelles formed with nonionic surfactant polyoxyethylene sorbitan monooleate (Tween 80), cosurfactant 1-pentanol, and linseed oil on the solubilization and desorption of organochlorine pesticides (OCPs) including DDT and γ-HCH from both loam soil and clay soil were investigated. Results showed that the solubilizing capacities of oil-swollen micelles were dependent on the critical micelle concentration (CMC) of Tween 80. Once the concentrations of oil-swollen micelles exceeded the CMC of Tween 80, the oil-swollen micelles exhibited much higher solubilizing capacity than empty Tween 80 micelles for the two OCPs. Desorption tests revealed that oil-swollen micelles could successfully enhance desorption of OCPs from both loam soil and clay soil. However, compared with the efficiencies achieved by empty Tween 80 micelles, oil-swollen micelles exhibited their superiority to desorb OCPs only in loam soil-water system while was less effective in clay soil-water system. Distribution of Tween 80, 1-pentanol and linseed oil in soil-water system revealed that the difference in the sorption behavior of linseed oil onto the two soils is responsible for the different effects of oil-swollen micelles on the desorption of OCPs in loam soil and clay soil systems. Therefore, oil-swollen micelles formed with nonionic surfactant Tween 80 are better candidates over empty micelle counterparts to desorb OCPs from soil with relatively lower sorption capacity for oil fraction, which may consequently enhance the availability of OCPs in soil environment during remediation processes of contaminated soil.

  9. Theranostic reduction-sensitive gemcitabine prodrug micelles for near-infrared imaging and pancreatic cancer therapy

    Science.gov (United States)

    Han, Haijie; Wang, Haibo; Chen, Yangjun; Li, Zuhong; Wang, Yin; Jin, Qiao; Ji, Jian

    2015-12-01

    A biodegradable and reduction-cleavable gemcitabine (GEM) polymeric prodrug with in vivo near-infrared (NIR) imaging ability was reported. This theranostic GEM prodrug PEG-b-[PLA-co-PMAC-graft-(IR820-co-GEM)] was synthesized by ring-opening polymerization and ``click'' reaction. The as-prepared reduction-sensitive prodrug could self-assemble into prodrug micelles in aqueous solution confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). In vitro drug release studies showed that these prodrug micelles were able to release GEM in an intracellular-mimicking reductive environment. These prodrug micelles could be effectively internalized by BxPC-3 pancreatic cancer cells, which were observed by confocal laser scanning microscopy (CLSM). Meanwhile, a methyl thiazolyl tetrazolium (MTT) assay demonstrated that this prodrug exhibited high cytotoxicity against BxPC-3 cells. The in vivo whole-animal near-infrared (NIR) imaging results showed that these prodrug micelles could be effectively accumulated in tumor tissue and had a longer blood circulation time than IR820-COOH. The endogenous reduction-sensitive gemcitabine prodrug micelles with the in vivo NIR imaging ability might have great potential in image-guided pancreatic cancer therapy.A biodegradable and reduction-cleavable gemcitabine (GEM) polymeric prodrug with in vivo near-infrared (NIR) imaging ability was reported. This theranostic GEM prodrug PEG-b-[PLA-co-PMAC-graft-(IR820-co-GEM)] was synthesized by ring-opening polymerization and ``click'' reaction. The as-prepared reduction-sensitive prodrug could self-assemble into prodrug micelles in aqueous solution confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). In vitro drug release studies showed that these prodrug micelles were able to release GEM in an intracellular-mimicking reductive environment. These prodrug micelles could be effectively internalized by BxPC-3 pancreatic cancer cells, which

  10. Improved hydrogen production by coupled systems of hydrogenase negative photosynthetic bacteria and fermentative bacteria in reverse micelles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anita [Centre for Biotechnology, University of Allahabad, Allahabad 211002 (India); Misra, Krishna [Indo-Russian Center for Bioinformatics, Indian Institute of Information Technology, Allahabad 211011 (India)

    2008-11-15

    Significant improvement in biological hydrogen production is achieved by the use of coupled bacterial cells in reverse micellar systems. Two coupled systems (a) Rhodopseudomonas palustris CGA009/Citrobacter Y19, and (b) Rhodobacter sphaeroides 2.4.1/Citrobacter Y19 bacteria have been immobilized separately in aqueous pool of the reverse micelles fabricated by various surfactants (AOT, CBAC and SDS) and apolar organic solvents (benzene and isooctane). The gene for uptake hydrogenase enzyme has been manipulated further for hydrogen generation. Mutants deficient in uptake hydrogenase (Hup{sup -}) were obtained from R. palustris CGA009 and R. sphaeroides 2.4.1, and entrapped with Citrobacter Y19 in the reverse micellar systems. More than two fold increase in hydrogen production was obtained by the use of Hup{sup -} mutants instead of wild-type photosynthetic bacteria together with Citrobacter Y19. Addition of sodium dithionite, a reducing agent to AOT/H{sub 2}O/isooctane reverse micellar system with the coupled systems of wild-type photosynthetic bacteria and fermentative bacterium Y19 effected similar increase in hydrogen production rate as it is obtained by the use of mutants. CBAC/H{sub 2}O/isooctane reverse micellar system is used for the first time for hydrogen production and is as promising as AOT/H{sub 2}O/isooctane reverse micellar system. All reverse micellar systems of coupled bacterial cultures gave encouraging hydrogen production (rate as well as yield) compared to uncoupled bacterial culture. (author)

  11. Interaction between cationic and conventional nonionic surfactants in the mixed micelle and monolayer formed in aqueous medium

    Directory of Open Access Journals (Sweden)

    Nabel A. Negm

    2011-01-01

    Full Text Available Mixed micellization and surface properties of cationic and nonionic surfactants dimethyl decyl-, tetradecyl- and hexadecyl phosphineoxide mixtures are studied using conductivity and surface tension measurements. The models of Rubingh, Rosen, and Clint, are used to obtain the interaction parameter, minimum area per molecule, mixed micelle composition, free energies of mixing and activity coefficients. The micellar mole fractions were always higher than ideal values indicating high contributions of cationics in mixed micelles. Activity coefficients were less than unity indicating synergism in micelles. The negative free energies of mixing showed the stability of the surfactants in the mixed micelles.

  12. Mixed micelles of lipoic acid-chitosan-poly(ethylene glycol) and distearoylphosphatidylethanolamine-poly(ethylene glycol) for tumor delivery.

    Science.gov (United States)

    Elsaid, Zeeneh; Taylor, Kevin M G; Puri, Sanyogitta; Eberlein, Cath A; Al-Jamal, Khuloud; Bai, Jie; Klippstein, Rebecca; Wang, Julie Tzu-Wen; Forbes, Ben; Chana, Jasminder; Somavarapu, Satyanarayana

    2017-04-01

    Many chemotherapeutics suffer from poor aqueous solubility and tissue selectivity. Distearoylphosphatidylethanolamine-poly(ethylene glycol) (DSPE-PEG) micelles are a promising formulation strategy for the delivery of hydrophobic anticancer drugs. However, storage and in vivo instability restrict their use. The aim of this study was to prepare mixed micelles, containing a novel polymer, lipoic acid-chitosan-poly(ethylene glycol) (LACPEG), and DSPE-PEG, to overcome these limitations and potentially increase cancer cell internalisation. Drug-loaded micelles were prepared with a model tyrosine kinase inhibitor and characterized for size, surface charge, stability, morphology, drug entrapment efficiency, cell viability (A549 and PC-9 cell lines), in vivo biodistribution, ex vivo tumor accumulation and cellular internalisation. Micelles of size 30-130nm with entrapment efficiencies of 46-81% were prepared. LACPEG/DSPE-PEG mixed micelles showed greater interaction with the drug (condensing to half their size following entrapment), greater stability, and a safer profile in vitro compared to DSPE-PEG micelles. LACPEG/DSPE-PEG and DSPE-PEG micelles had similar entrapment efficiencies and in vivo tumor accumulation levels, but LACPEG/DSPE-PEG micelles showed higher tumor cell internalisation. Collectively, these findings suggest that LACPEG/DSPE-PEG mixed micelles provide a promising platform for tumor delivery of hydrophobic drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Self-assembled micelles of amphiphilic poly(L-phenylalanine-b-poly(L-serine polypeptides for tumor-targeted delivery

    Directory of Open Access Journals (Sweden)

    Zhao ZM

    2014-12-01

    Full Text Available Ziming Zhao,1,2,* Yu Wang,1,2,* Jin Han,1,2 Keli Wang,1 Dan Yang,1,2 Yihua Yang,1,2 Qian Du,1,2 Yuanjian Song,3 Xiaoxing Yin1,2 1Department of Pharmacy, 2Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, 3Department of Basic Medical Sciences, Xuzhou Medical College, Xuzhou, People’s Republic of China *These authors contributed equally to this work Abstract: The aim of this work was to design, synthesize, and characterize self-assembled micelles based on polypeptides as a potential antitumor drug carrier. Amphiphilic poly(L-phenylalanine-b-poly(L-serine (PFS polypeptides were obtained through the polymerization of N-carboxyanhydride. As a novel hydrophilic segment, poly(L-serine was utilized to enhance tumor targeting due to a large demand of tumors for serine. PFS could self-assemble into micelles with an average diameter of 110–240 nm and a slightly negative charge. PFS polypeptides adopted random coil in pH 7.4 phosphate-buffered saline and could partly transform to a-helix induced by trifluoroethanol. PFS micelles with a low critical micelle concentration of 4.0 µg mL-1 were stable in pH 5–9 buffers and serum albumin solution. PFS micelles had a loading capacity of 3.8% for coumarin-6 and exhibited a sustained drug release. Coumarin-6 loaded rhodamine B isothiocyanate-labeled PFS micelles were incubated with Huh-7 tumor cells to study the correlation between drugs and carriers during endocytosis. The uptake of drugs was consistent with the micelles, illustrating that the intracellular transport of drugs highly depended on the micelles. PFS micelles diffused in whole cytoplasm while coumarin-6 assumed localized distribution, suggesting that the micelles could release the loaded drugs in particular areas. The internalization mechanism of PFS micelles was involved with clathrin-mediated endocytosis and macropinocytosis. Excess serine inhibited the uptake of PFS micelles, which demonstrated that serine receptors played

  14. Phase Behavior and Aggregate Structure in Aqueous Mixtures of Sodium Cholate and Glycerol Monooleate.

    Science.gov (United States)

    Gustafsson; Nylander; Almgren; Ljusberg-Wahren

    1999-03-15

    The phase behavior of the glycerol monooleate (GMO)-sodium cholate-water (or 0.9 wt% NaCl) system has been examined in the solvent-rich part, using small-angle X-ray scattering and conventional methods. Addition of cholate up to 7% of the total amphiphile swells the cubic phase of the binary GMO-water system so that it takes up almost 70% of water in the salt-free case and 55% in salt. With more bile salt the lamellar phase also appears highly swollen (up to 85% in water, 75% in brine). In the salt solution a small isotropic L3-phase region replaces the lamellar phase at a solvent content of about 79%. The lamellar phase can accept only about 0.2 cholate molecule per GMO, in both water and brine, and a phase with globular micelles (L1) follows and dominates the diagram. No threadlike micelles appear in this system. Investigation of the particle structures with cryo-transmission electron microscopy (TEM) in dilute systems (99% solvent) show globular micelles and coexisting vesicles and globular micelles. In the presence of salt, dilution of the L3 phase results in dispersed globular particles with an irregular internal morphology that suggests they are a dispersed L3 phase. These particles coexist with faceted particles having an inner structure giving a hexagonal pattern in projection, suggested to derive from the cubic phase. The cubic phase in the salt-free systems did not give dispersions stable enough for cryo-TEM examination. Copyright 1999 Academic Press.

  15. Cardiac sodium channelopathies.

    Science.gov (United States)

    Amin, Ahmad S; Asghari-Roodsari, Alaleh; Tan, Hanno L

    2010-07-01

    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (INa) during phase 0 of the cardiac action potential. The importance of INa for normal cardiac electrical activity is reflected by the high incidence of arrhythmias in cardiac sodium channelopathies, i.e., arrhythmogenic diseases in patients with mutations in SCN5A, the gene responsible for the pore-forming ion-conducting alpha-subunit, or in genes that encode the ancillary beta-subunits or regulatory proteins of the cardiac sodium channel. While clinical and genetic studies have laid the foundation for our understanding of cardiac sodium channelopathies by establishing links between arrhythmogenic diseases and mutations in genes that encode various subunits of the cardiac sodium channel, biophysical studies (particularly in heterologous expression systems and transgenic mouse models) have provided insights into the mechanisms by which INa dysfunction causes disease in such channelopathies. It is now recognized that mutations that increase INa delay cardiac repolarization, prolong action potential duration, and cause long QT syndrome, while mutations that reduce INa decrease cardiac excitability, reduce electrical conduction velocity, and induce Brugada syndrome, progressive cardiac conduction disease, sick sinus syndrome, or combinations thereof. Recently, mutation-induced INa dysfunction was also linked to dilated cardiomyopathy, atrial fibrillation, and sudden infant death syndrome. This review describes the structure and function of the cardiac sodium channel and its various subunits, summarizes major cardiac sodium channelopathies and the current knowledge concerning their genetic background and underlying molecular mechanisms, and discusses recent advances in the discovery of mutation-specific therapies in the management of these channelopathies.

  16. Low Critical Micelle Concentration Discrepancy between Theory and Experiment.

    Science.gov (United States)

    García Daza, Fabián A; Mackie, Allan D

    2014-06-05

    Experimental measurements for a variety of surfactants unexpectedly show that the critical micelle concentration (CMC) becomes constant with respect to increasing the size of the hydrophobic tail. This observation disagrees with theoretical models where it is expected to continue to decrease exponentially. Because of the lack of a satisfactory explanation for such a discrepancy from theory, we have studied these systems using a coarse-grained model within the single-chain mean field (SCMF) theory combined with relevant micellar kinetic effects. In particular, a microscopic model for poly(ethylene oxide) alkyl ether was applied to describe a series of nonionic gemini surfactants. When kinetic effects are used to correct the equilibrium CMC values from the SCMF scheme together with the loss of surfactants due to adsorption on the experimental recipient, it is possible to reproduce the correct order of magnitude of the experimental CMC results. Hence it appears that the experimental values disagree with the theoretical predictions because they are not true equilibrium values due to the fact that the time scales for these low CMC values become astronomically large.

  17. Determination of critical micelle concentration with the rotating sample system.

    Science.gov (United States)

    Kao, Linus T; Shetty, Gautam N; Gratzl, Miklós

    2008-12-01

    A novel experimental approach using the rotating sample system (RSS) is proposed here for the determination of the critical micelle concentration (CMC) of surfactants. The RSS has been conceived in our laboratory as a convection platform for physicochemical studies and analyses in microliter-sized sample drops. The scheme allows for vigorous rotation of the drop despite its small size through efficient air-liquid mechanical coupling. Thus, changes in surface properties of aqueous samples result in corresponding modulation of the hydrodynamic performance of the RSS, which can be utilized to investigate interfacial phenomena. In this work, we demonstrate that the RSS can be used to study the effects of surfactants on the surface and in the bulk of very small samples with hydrodynamic electrochemistry. Potassium ferrocyanide is employed here with cyclic voltammetry to probe the air-water interface of solutions containing Triton X-100. The CMC of this surfactant determined using this approach is 140 ppm, which agrees well with reported values obtained with conventional methods in much larger samples. The results also demonstrate that besides the CMC, variations in bulk rheological properties can also be investigated in very small specimens using the RSS with a simple method.

  18. Crystalline free energies of micelles of diblock copolymer solutions

    CERN Document Server

    D'Adamo, Giuseppe; 10.1063/1.3509391

    2012-01-01

    We report a characterization of the relative stability and structural behavior of various micellar crystals of an athermal model of AB-diblock copolymers in solution. We adopt a previously devel- oped coarse-graining representation of the chains which maps each copolymer on a soft dumbbell. Thanks to this strong reduction of degrees of freedom, we are able to investigate large aggregated systems, and for a specific length ratio of the blocks f = MA/(MA + MB) = 0.6, to locate the order-disorder transition of the system of micelles. Above the transition, mechanical and thermal properties are found to depend on the number of particles per lattice site in the simulation box, and the application of a recent methodology for multiple occupancy crystals (B.M. Mladek et al., Phys. Rev. Lett. 99, 235702 (2007)) is necessary to correctly define the equilibrium state. Within this scheme we have performed free energy calculations at two reduced density {\\rho}/{\\rho}\\ast = 4,5 and for several cubic structures as FCC,BCC,A1...

  19. Biochemical synthesis of gold and zinc nanoparticles in reverse micelles

    Science.gov (United States)

    Egorova, E. M.

    2010-04-01

    Gold and zinc nanoparticles were obtained in AOT reverse micelles in isooctane by reduction of the corresponding metal ions by the natural pigment quercetin (the biochemical synthesis technique). Gold and zinc ions were introduced into the micellar solution of quercetin in the form of aqueous solutions, HAuCl4 and [Zn(NH3)4]SO4, to the water to AOT molar ratios 1-3 and 3-4, respectively. The process of nanoparticle formation was investigated by spectrophotometry. Nanoparticle size and shape were determined by transmission electron microscopy. The data obtained allow to conclude that there are two steps in metal ion-quercetin interaction: (1) complex formation, and (2) complex dissociation with subsequent formation of nanoparticles and a second product, presumably oxidized quercetin. Gold nanoparticles were found to be of various shapes (spheres, hexahedrons, triangles, and cylinders) and sizes, mainly in the 10-20 nm range; zinc nanoparticles are chiefly spherical and ˜5 nm in size. In both cases, the nanoparticles are stable in the air in micellar solution over long periods of time (from a several months to a several years).

  20. Atorvastatin-loaded micelles with bone-targeted ligand for the treatment of osteoporosis.

    Science.gov (United States)

    Xie, Yonghui; Tan, Xueying; Huang, Jian; Huang, Hongwei; Zou, Ping; Hu, Jingbo

    2017-11-01

    Osteoporosis is a common bone disorder where the declined bone mass is far more than normal physiological status and usually associated with enhanced fracture risk, reduced bone strength and even deteriorated quality of life. Recent studies showed that statins could exert beneficial effects on bones via promoting osteoblastic activity mediated by increased expression of bone morphogenetic protein 2 and also by suppressing osteoclast proliferation. In this study, we developed atorvastatin-loaded tetracycline-poly (ethylene glycol)-poly(lactic-co-glycolic acid) (TC-PEG-PLGA/ATO) micelles for the targeted treatment of osteoporosis. The TC-PEG-PLGA was synthesized under the action of coupling reagents and then ATO was encapsulated through solvent diffusion method with encapsulation efficiency and drug loading of 89.32 ± 2.48% and 8.20 ± 0.53%, respectively. The release of ATO from micelles could be maintained for more than 48 h in pH 7.4 PBS. Pharmacokinetic results further demonstrated that TC-PEG-PLGA micelles could effectively shield ATO leakage from micelles and prolong their circulation time. Benefiting from TC specifically binding to hydroxyapatite (HAp), TC-PEG-PLGA/ATO micelles exerted good bone-targeted ability, as demonstrated by in vitro HAp affinity assay and biodistribution. Pharmacodynamic studies showed that TC-PEG-PLGA/ATO micelles could effectively improve bone mineral density and bone mechanical strength in osteoporotic rats. These results suggest that TC-PEG-PLGA/ATO micelles hold significant promise for the targeted treatment of osteoporosis.

  1. Investigations on the lyophilisation of MPEG-hexPLA micelle based pharmaceutical formulations.

    Science.gov (United States)

    Di Tommaso, Claudia; Como, Caterina; Gurny, Robert; Möller, Michael

    2010-04-16

    Lyophilisation is a common procedure to increase the long-term stability of pharmaceutical formulations. Its applicability to polymeric micelles is usually an issue because of the aggregation of materials during freeze-drying steps. The feasibility of this process was studied on polymeric micelles based on methoxy poly(ethylene glycol)-poly(hexyl-lactide) (MPEG-hexPLA) with and without Cyclosporin A, in order to increase the stability of these pharmaceutical formulations. Freeze-thawing tests were carried out to determine the protective effect of various excipients on the freezing step. Mannitol, trehalose, glucose and sucrose showed the best effectiveness in micelle protection. The lyophilisation process was optimised by thermal analysis (DSC) on excipients to determine the glass transition temperature of the cryoconcentrate solutions (T(g)') and their glass transition temperature (T(g)). The freeze-dried powders were characterized in terms of morphology (SEM) and of moisture content (Karl Fisher titration). The reconstituted micelle formulations were analysed for size by DLS with and without goniometer, for morphology by TEM, for drug loading by HPLC. The formulation presenting the best characteristics before and after reconstitution contained 10% (w/v) sucrose in phosphate buffer. This lyophilised formulation was constituted of a brittle and white cake, with a residual water content of around 2% and it was easily reconstituted in a transparent and clear solution giving back a colloidal system with spherical micelles in the submicron range (study showed that the MPEG-hexPLA micelles can be efficiently lyophilised and this process can be usefully applied to increase the pharmaceutical stability of these pharmaceutical micelle formulations. 2010 Elsevier B.V. All rights reserved.

  2. pH-sensitive micelles for targeted drug delivery prepared using a novel membrane contactor method.

    Science.gov (United States)

    Laouini, Abdallah; Koutroumanis, Konstantinos P; Charcosset, Catherine; Georgiadou, Stella; Fessi, Hatem; Holdich, Richard G; Vladisavljević, Goran T

    2013-09-25

    A novel membrane contactor method was used to produce size-controlled poly(ethylene glycol)-b-polycaprolactone (PEG-PCL) copolymer micelles composed of diblock copolymers with different average molecular weights, Mn (9200 or 10,400 Da) and hydrophilic fractions, f (0.67 or 0.59). By injecting 570 L m(-2) h(-1) of the organic phase (a 1 mg mL(-1) solution of PEG-PCL in tetrahydrofuran) through a microengineered nickel membrane with a hexagonal pore array and 200 μm pore spacing into deionized water agitated at 700 rpm, the micelle size linearly increased from 92 nm for a 5-μm pore size to 165 nm for a 40-μm pore size. The micelle size was finely tuned by the agitation rate, transmembrane flux and aqueous to organic phase ratio. An encapsulation efficiency of 89% and a drug loading of ~75% (w/w) were achieved when a hydrophobic drug (vitamin E) was entrapped within the micelles, as determined by ultracentrifugation method. The drug-loaded micelles had a mean size of 146 ± 7 nm, a polydispersity index of 0.09 ± 0.01, and a ζ potential of -19.5 ± 0.2 mV. When drug-loaded micelles where stored for 50 h, a pH sensitive drug release was achieved and a maximum amount of vitamin E (23%) was released at the pH of 1.9. When a pH-sensitive hydrazone bond was incorporated between PEG and PCL blocks, no significant change in micelle size was observed at the same micellization conditions.

  3. Cytotoxicity Study on Luminescent Nanocrystals Containing Phospholipid Micelles in Primary Cultures of Rat Astrocytes

    Science.gov (United States)

    Valente, Gianpiero; Fanizza, Elisabetta; Laquintana, Valentino; Denora, Nunzio; Fasano, Anna; Striccoli, Marinella; Colella, Matilde; Agostiano, Angela; Curri, M. Lucia; Liuzzi, Grazia Maria

    2016-01-01

    Luminescent colloidal nanocrystals (NCs) are emerging as a new tool in neuroscience field, representing superior optical probes for cellular imaging and medical diagnosis of neurological disorders with respect to organic fluorophores. However, only a limited number of studies have, so far, explored NC applications in primary neurons, glia and related cells. Indeed astrocytes, as resident cells in the central nervous system (CNS), play an important pathogenic role in several neurodegenerative and neuroinflammatory diseases, therefore enhanced imaging tools for their thorough investigation are strongly amenable. Here, a comprehensive and systematic study on the in vitro toxicological effect of core-shell type luminescent CdSe@ZnS NCs incorporated in polyethylene glycol (PEG) terminated phospholipid micelles on primary cultures of rat astrocytes was carried out. Cytotoxicity response of empty micelles based on PEG modified phospholipids was compared to that of their NC containing counterpart, in order to investigate the effect on cell viability of both inorganic NCs and micelles protecting NC surface. Furthermore, since the surface charge and chemistry influence cell interaction and toxicity, effect of two different functional groups terminating PEG-modified phospholipid micelles, namely amine and carboxyl group, respectively, was evaluated against bare micelles, showing that carboxyl group was less toxic. The ability of PEG-lipid micelles to be internalized into the cells was qualitatively and quantitatively assessed by fluorescence microscopy and photoluminescence (PL) assay. The results of the experiments clearly demonstrate that, once incorporated into the micelles, a low, not toxic, concentration of NCs is sufficient to be distinctly detected within cells. The overall study provides essential indications to define the optimal experimental conditions to effectively and profitably use the proposed luminescent colloidal NCs as optical probe for future in vivo

  4. Dependence of micelle size and shape on detergent alkyl chain length and head group.

    Directory of Open Access Journals (Sweden)

    Ryan C Oliver

    Full Text Available Micelle-forming detergents provide an amphipathic environment that can mimic lipid bilayers and are important tools for solubilizing membrane proteins for functional and structural investigations in vitro. However, the formation of a soluble protein-detergent complex (PDC currently relies on empirical screening of detergents, and a stable and functional PDC is often not obtained. To provide a foundation for systematic comparisons between the properties of the detergent micelle and the resulting PDC, a comprehensive set of detergents commonly used for membrane protein studies are systematically investigated. Using small-angle X-ray scattering (SAXS, micelle shapes and sizes are determined for phosphocholines with 10, 12, and 14 alkyl carbons, glucosides with 8, 9, and 10 alkyl carbons, maltosides with 8, 10, and 12 alkyl carbons, and lysophosphatidyl glycerols with 14 and 16 alkyl carbons. The SAXS profiles are well described by two-component ellipsoid models, with an electron rich outer shell corresponding to the detergent head groups and a less electron dense hydrophobic core composed of the alkyl chains. The minor axis of the elliptical micelle core from these models is constrained by the length of the alkyl chain, and increases by 1.2-1.5 Å per carbon addition to the alkyl chain. The major elliptical axis also increases with chain length; however, the ellipticity remains approximately constant for each detergent series. In addition, the aggregation number of these detergents increases by ∼16 monomers per micelle for each alkyl carbon added. The data provide a comprehensive view of the determinants of micelle shape and size and provide a baseline for correlating micelle properties with protein-detergent interactions.

  5. Development of casein microgels from cross-linking of casein micelles by genipin.

    Science.gov (United States)

    Silva, Naaman F Nogueira; Saint-Jalmes, Arnaud; de Carvalho, Antônio F; Gaucheron, Frédéric

    2014-09-02

    Casein micelles are porous colloidal particles, constituted of casein molecules, water, and minerals. The vulnerability of the supramolecular structure of casein micelles face to changes in the environmental conditions restrains their applications in other domains besides food. Thus, redesigning casein micelles is a challenge to create new functionalities for these biosourced particles. The objective of this work was to create stable casein microgels from casein micelles using a natural cross-linker, named genipin. Suspensions of purified casein micelles (25 g L(-1)) were mixed with genipin solutions to have final concentrations of 5, 10, and 20 mM genipin. Covalently linked casein microgels were formed via cross-linking of lysyl and arginyl residues of casein molecules. The reacted products exhibited blue color. The cross-linking reaction induced gradual changes on the colloidal properties of the particles. The casein microgels were smaller and more negatively charged and presented smoother surfaces than casein micelles. These results were explained based on the cross-linking of free NH2 present in an external layer of κ-casein. Light scattering and rheological measurements showed that the reaction between genipin and casein molecules was intramicellar, as one single population of particles was observed and the values of viscosity (and, consequently, the volume fraction of the particles) were reduced. Contrary to the casein micelles, the casein microgels were resistant to the presence of dissociating agents, e.g., citrate (calcium chelating) and urea, but swelled as a consequence of internal electrostatic repulsion and the disruption of hydrophobic interactions between protein chains. The casein microgels did not dissociate at the air-solution interface and formed solid-like interfaces rather than a viscoelastic gel. The potential use of casein microgels as adaptable nanocarriers is proposed in the article.

  6. Development of sodium technology

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Sung Tai; Nam, H. Y.; Choi, Y. D. [and others

    2000-05-01

    The objective of present study is to produce the experimental data for development and verification of computer codes for development of LMR and to develop the preliminary technologies for the future large scale verification experiments. A MHD experimental test loop has been constructed for the quantitative analysis of the effect of magnetic field on the sodium flow and experiments are carried out for three EM pumps. The previous pressure drop correlations are evaluated using the experimental data obtained from the pressure drop experiment in a 19-pin fuel assembly with wire spacer. An dimensionless variable is proposed to describe the amplitude and frequency of the fluctuation of free surface using the experimental data obtained from free surface experimental apparatus and an empirical correlation is developed using this dimensionless variable. An experimental test loop is constructed to measure the flow characteristics in IHX shell side and the local pressure drop in fuel assembly, and to test the vibration behaviour of fuel pins due to flow induced vibration. The sodium two-phase flow measuring technique using the electromagnetic flowmeter is developed and the sodium differential pressure drop measuring technique using the method of direct contact of sodium and oil is established. The work on the analysis of sodium fire characteristics and produce data for vlidation of computer code is performed. Perfect reopen time of self plugged leak path was observed to be about 130 minutes after water leak initiation. Reopen shape of a specimen appeared to be double layer of circular type, and reopen size of this specimen surface was about 2mm diameter on sodium side. In small water leakage experiments, the following correlation equation about the reopen time between sodium temperature and initial leak rate was obtained, {tau}{sub c} = {delta}{center_dot}g{sup -0.83}{center_dot}10{sup (3570/T{sub Na}-3.34)}, in 400-500 deg C of liquid sodium atmosphere. The characteristics

  7. Melting of sodium clusters

    CERN Document Server

    Reyes-Nava, J A; Beltran, M R; Michaelian, K

    2002-01-01

    Thermal stability properties and the melting-like transition of Na_n, n=13-147, clusters are studied through microcanonical molecular dynamics simulations. The metallic bonding in the sodium clusters is mimicked by a many-body Gupta potential based on the second moment approximation of a tight-binding Hamiltonian. The characteristics of the solid-to-liquid transition in the sodium clusters are analyzed by calculating physical quantities like caloric curves, heat capacities, and root-mean-square bond length fluctuations using simulation times of several nanoseconds. Distinct melting mechanisms are obtained for the sodium clusters in the size range investigated. The calculated melting temperatures show an irregular variation with the cluster size, in qualitative agreement with recent experimental results. However, the calculated melting point for the Na_55 cluster is about 40 % lower than the experimental value.

  8. Static structure factor of polymerlike micelles: Overall dimension, flexibility, and local properties of lecithin reverse micelles in deuterated isooctane

    Science.gov (United States)

    Jerke, Götz; Pedersen, Jan Skov; Egelhaaf, Stefan Ulrich; Schurtenberger, Peter

    1997-11-01

    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 concentrations in the dilute and semidilute regime cover approximately three decades of scattering vectors. The data have been analyzed using polymer renormalization-group theory and a nonlinear least-squares fitting procedure based upon a numerical expression for the single chain scattering function of a wormlike chain with excluded-volume effects. Furthermore, the influence of interaction effects on the static structure factor have been successfully examined within a modified random-phase approximation. Additional information on the local scale has been extracted by applying indirect Fourier transformation and square-root deconvolution techniques. We demonstrate that we can determine structural properties such as the micellar cross-section profile and flexibility as well as quantitatively incorporate the influence of micellar growth and excluded-volume effects on S(q,c).

  9. Biochemical characterization of the interactions between doxorubicin and lipidic GM1 micelles with or without paclitaxel loading

    Science.gov (United States)

    Leonhard, Victoria; Alasino, Roxana V; Bianco, Ismael D; Garro, Ariel G; Heredia, Valeria; Beltramo, Dante M

    2015-01-01

    Doxorubicin (Dox) is an anthracycline anticancer drug with high water solubility, whose use is limited primarily due to significant side effects. In this study it is shown that Dox interacts with monosialoglycosphingolipid (GM1) ganglioside micelles primarily through hydrophobic interactions independent of pH and ionic strength. In addition, Dox can be incorporated even into GM1 micelles already containing highly hydrophobic paclitaxel (Ptx). However, it was not possible to incorporate Ptx into Dox-containing GM1 micelles, suggesting that Dox could be occupying a more external position in the micelles. This result is in agreement with a higher hydrolysis of Dox than of Ptx when micelles were incubated at alkaline pH. The loading of Dox into GM1 micelles was observed over a broad range of temperature (4°C–55°C). Furthermore, Dox-loaded micelles were stable in aqueous solutions exhibiting no aggregation or precipitation for up to 2 months when kept at 4°C–25°C and even after freeze–thawing cycles. Upon exposure to blood components, Dox-containing micelles were observed to interact with human serum albumin. However, the amount of human serum albumin that ended up being associated to the micelles was inversely related to the amount of Dox, suggesting that both could share their binding sites. In vitro studies on Hep2 cells showed that the cellular uptake and cytotoxic activity of Dox and Ptx from the micellar complexes were similar to those of the free form of these drugs, even when the micelle was covered with albumin. These results support the idea of the existence of different nano-domains in a single micelle and the fact that this micellar model could be used as a platform for loading and delivering hydrophobic and hydrophilic active pharmaceutical ingredients. PMID:26005348

  10. Synthesis, Surface Active Properties and Cytotoxicity of Sodium N-Acyl Prolines.

    Science.gov (United States)

    Sreenu, Madhumanchi; Narayana Prasad, Rachapudi Badari; Sujitha, Pombala; Kumar, Chityal Ganesh

    2015-01-01

    Sodium N-acyl prolines (NaNAPro) were synthesized using mixture of fatty acids obtained from coconut, palm, karanja, Sterculia foetida and high oleic sunflower oils via Schotten-Baumann reaction in 58-75% yields to study the synergetic effect of mixture of hydrophobic fatty acyl functionalities like saturation, unsaturation and cyclopropene fatty acids with different chain lengths and aliphatic hetero cyclic proline head group on their surface and cytotoxicity activities. The products were characterized by chromatographic and spectral techniques. The synthesized products were evaluated for their surface active properties such as surface tension, wetting power, foaming characteristics, emulsion stability, calcium tolerance, critical micelle concentration (CMC) and thermodynamic properties. The results revealed that all the products exhibited superior surface active properties like CMC, calcium tolerance and emulsion stability as compared to the standard surfactant, sodium lauryl sulphate (SLS). In addition, palm, Sterculia foetida and high oleic sunflower fatty N-acyl prolines exhibited promising cytotoxicity against different tumor cell lines.

  11. Synthesis of the Hemoglobin-Conjugated Polymer Micelles by Thiol Michael Addition Reactions.

    Science.gov (United States)

    Qi, Yanxin; Li, Taihang; Wang, Yupeng; Wei, Xing; Li, Bin; Chen, Xuesi; Xie, Zhigang; Jing, Xiabin; Huang, Yubin

    2016-06-01

    Amphiphilic triblock copolymers mPEG-b-PMAC-b-PCL are synthesized using methoxyl poly(ethylene glycol), cyclic carbonic ester monomer including acryloyl group, and ε-caprolactone. Copolymers are self-assembled into core-shell micelles in aqueous solution. Thiolated hemoglobin (Hb) is conjugated with micelles sufficiently through thiol Michael addition reaction to form hemoglobin nanoparticles (HbNs) with 200 nm in diameter. The conjugation of Hb onto the micelle surface is further confirmed by X-ray photoelectron spectroscopy. Feeding ratio of copolymer micelles to Hb at 1:3 would lead to the highest hemoglobin loading efficiency 36.7 wt%. The UV results demonstrate that the gas transporting capacity of HbNs is well remained after Hb is conjugated with polymeric micelles. Furthermore, the obtained HbNs have no obvious detrimental effects on blood components in vitro. This system may thus have great potential as one of the candidates to be developed as oxygen carriers and provide a reference for the modification of protein drugs.

  12. Oleyl-hyaluronan micelles loaded with upconverting nanoparticles for bio-imaging

    Energy Technology Data Exchange (ETDEWEB)

    Pospisilova, Martina, E-mail: martina.pospisilova@contipro.com; Mrazek, Jiri; Matuska, Vit; Kettou, Sofiane; Dusikova, Monika; Svozil, Vit; Nesporova, Kristina; Huerta-Angeles, Gloria; Vagnerova, Hana; Velebny, Vladimir [Contipro Biotech (Czech Republic)

    2015-09-15

    Hyaluronan (HA) represents an interesting polymer for nanoparticle coating due to its biocompatibility and enhanced cell interaction via CD44 receptor. Here, we describe incorporation of oleate-capped β–NaYF{sub 4}:Yb{sup 3+}, Er{sup 3+} nanoparticles (UCNP-OA) into amphiphilic HA by microemulsion method. Resulting structures have a spherical, micelle-like appearance with a hydrodynamic diameter of 180 nm. UCNP-OA-loaded HA micelles show a good stability in PBS buffer and cell culture media. The intensity of green emission of UCNP-OA-loaded HA micelles in water is about five times higher than that of ligand-free UCNP, indicating that amphiphilic HA effectively protects UCNP luminescence from quenching by water molecules. We found that UCNP-OA-loaded HA micelles in concentrations up to 50 μg mL{sup −1} increase cell viability of normal human dermal fibroblasts (NHDF), while viability of human breast adenocarcinoma cells MDA–MB–231 is reduced at these concentrations. The utility of UCNP-OA-loaded HA micelles as a bio-imaging probe was demonstrated in vitro by successful labelling of NHDF and MDA–MB–231 cells overexpressing the CD44 receptor.

  13. Comparative evaluation of polymersome versus micelle structures as vehicles for the controlled release of drugs

    Energy Technology Data Exchange (ETDEWEB)

    Alibolandi, Mona [Mashhad University of Medical Sciences, Biotechnology Research Center, School of Pharmacy (Iran, Islamic Republic of); Ramezani, Mohammad; Abnous, Khalil [Mashhad University of Medical Sciences, Pharmaceutical Research Center, School of Pharmacy (Iran, Islamic Republic of); Sadeghi, Fatemeh, E-mail: sadeghif@mums.ac.ir [Mashhad University of Medical Sciences, Targeted Drug Delivery Research Center, School of Pharmacy (Iran, Islamic Republic of); Hadizadeh, Farzin, E-mail: hadizadehf@mums.ac.ir [Mashhad University of Medical Sciences, Biotechnology Research Center, School of Pharmacy (Iran, Islamic Republic of)

    2015-02-15

    Di-block copolymers composed of two biocompatible polymers, poly(ethylene glycol) and poly(d,l-lactide), were synthesized by ring-opening polymerization for the preparation of doxorubicin-loaded self-assembled nanostructures, including polymeric vesicles (polymersomes) and micelles. The capability and stability of the nanostructures prepared for the controlled release of DOX are discussed in this paper. The in vitro drug release at 37 °C was evaluated up to 6 days at pH 7.4 and 5.5 and in the presence of 50 % FBS. The cellular uptake and cytotoxicity effect of both formulations were also evaluated in the MCF-7 cell line. The SEM and AFM images confirmed the hollow spherical structure of the polymersomes and the solid round structures of the micelles. The TEM results also revealed the uniformity in size and shape of the drug-loaded micelle and polymersome nanostructures. The DOX-loaded micelles and polymersomes presented efficient anticancer performance, as verified by flow cytometry and MTT assay tests. The most important finding of this study is that the prepared nanopolymersomes presented significant increases in the doxorubicin encapsulation efficiency and the stability of the formulation in comparison with the micelle formulation. In vitro studies revealed that polymersomes may be stable in the blood circulation and meet the requirements for an effective drug delivery system.

  14. Preparation and Characterization of a pH-Responsive Core Cross-linked Polymer Micelle

    Energy Technology Data Exchange (ETDEWEB)

    Kousaka, Shouta; Sugahara, Makoto; Endo, Tatsuya; Yusa, Shin-ichi, E-mail: yusa@eng.u-hyogo.ac.jp [Department of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan)

    2011-01-01

    Poly(ethylene glycol)-b-poly(2-(diethylamino) ethyl methacrylate-co-2-cinnamoyl-oxyethyl acrylate) (PEG-b-P(DEA/CEA)) was prepared by reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization. pH-responsive association behaviour of PEG-b-P(DEA/CEA) in 0.1 M NaCl was characterized by dynamic light scattering (DLS). As solution pH is increased from an acidic pH, the hydrodynamic radius (R{sub h}) increases, indicative of the polymer micelle formation. The formation of a micelle was also supported by static light scattering (SLS) data. The cinnamoyl groups in the core of the polymer micelle undergo photodimerization, yielding cross-links between polymer chains. The core of the polymer micelle was fixed, which was confirmed by DLS, SLS, and small angle X-ray scattering (SAXS) techniques. When pH is decreased to 3, R{sub h} of the core cross-linked (CCL) polymer micelle slightly increases due to the protonation of the DEA unit in the cross-linked core. The reversible pH-induced swelling and shrinking behaviour can be observed.

  15. NMR characterization of membrane protein-detergent micelle solutions by use of microcoil equipment.

    Science.gov (United States)

    Stanczak, Pawel; Horst, Reto; Serrano, Pedro; Wüthrich, Kurt

    2009-12-30

    Using microcoil NMR technology, the uniformly (2)H,(15)N-labeled integral membrane protein OmpX, and the phosphocholine derivative detergent Fos-10 (n-decylphosphocholine), we investigated solutions of mixed protein-detergent micelles to determine the influence of the detergent concentration on the NMR spectra of the protein. In a first step, we identified key parameters that influence the composition of the micelle solutions, which resulted in a new protocol for the preparation of well-defined concentrated protein solutions. This led to the observation that high-quality 2D [(15)N,(1)H]-transverse relaxation-optimized spectroscopy (TROSY) spectra of OmpX reconstituted in mixed micelles with Fos-10 were obtained only in a limited range of detergent concentrations. Outside of this range from about 90-180 mM, we observed a significant decrease of the average peak intensity. Relaxation-optimized NMR measurements of the rotational and translational diffusion coefficients of the OmpX/Fos-10 mixed micelles, D(r) and D(t), respectively, then showed that the stoichiometry and the effective hydrodynamic radius of the protein-containing micelles are not significantly affected by high Fos-10 concentrations and that the deterioration of NMR spectra is due to the increased viscosity at high detergent concentrations. The paper thus provides a basis for refined guidelines on the preparation of integral membrane proteins for structural studies.

  16. Preparation of novel ferrocene-based shell cross-linked thermoresponsive hybrid micelles with antitumor efficacy.

    Science.gov (United States)

    Wei, Hua; Quan, Chang-Yun; Chang, Cong; Zhang, Xian-Zheng; Zhuo, Ren-Xi

    2010-04-29

    The shell cross-linked (SCL) thermoresponsive hybrid poly(N-isopropylacrylamide-co-aminoethyl methacrylate)-b-polymethyl methacrylate (P(NIPAAm-co-AMA)-b-PMMA) micelle consisting of a cross-linked thermoresponsive hybrid shell and a hydrophobic core domain was fabricated via a two-step process: micellization of P(NIPAAm-co-AMA)-b-PMMA in aqueous solution followed by cross-linking of the hydrophilic shell layer via the amidation reaction between the amine groups of AMA units and the carboxylic acid functions of 1,1'-ferrocenedicarboxylic acid. The SCL micelle showed reversible dispersion/aggregation in response to the temperature cycles through the lower critical solution temperature (LCST) of the thermoresponsive hybrid shell at around 36 degrees C, observed by turbidity measurements and dynamic light scattering (DLS). Besides the usage as an inorganic difunctional cross-linker, the inorganic ferrocene segment further endowed the SCL hybrid micelle with the antitumor efficacy, namely, the resulting SCL micelle exhibited a remarkable cytotoxic effect for HeLa cells with a very low IC50. The results showed that the SCL hybrid micelle developed in this study could be potentially used as an antitumor agent, which is unique compared to the conventional tumor therapy by using the antitumor drug loaded in the micellar core.

  17. Micelles assembled with carbocyanine dyes for theranostic near-infrared fluorescent cancer imaging and photothermal therapy.

    Science.gov (United States)

    Yang, Hong; Mao, Huajian; Wan, Zhihui; Zhu, Aijun; Guo, Miao; Li, Yanli; Li, Xinming; Wan, Jiangling; Yang, Xiangliang; Shuai, Xintao; Chen, Huabing

    2013-12-01

    It is an emerging focus to explore a theranostic nanocarrier for simultaneous cancer imaging and therapy. Herein, we demonstrate a theranostic micelle system for cancer near infrared fluorescent (NIRF) imaging with enhanced signal to noise ratio and superior photothermal therapy. The copolymers consisting of monomethoxy poly(ethylene glycol) and alkylamine-grafted poly(L-aspartic acid) are assembled with carbocyanine dyes into theranostic micelles, which exhibit small size, high loading capacity, good stability, sustained release behavior, and enhanced cellular uptake. The micelles achieve the preferable biodistribution and long-term retention of carbocyanine dyes at tumor, which result in enhanced NIRF imaging by generating stable retention of NIRF signals at both hypervascular and hypovascular tumors during a long-term imaging period of up to 8 day, accompanying with negligible noise at normal tissues. The photostability of carbocyanine dye (Cypate) plays an important role for long-term cancer imaging with enhanced SNR. Moreover, the micelles exhibit severe photothermal damage on cancer cells via the destabilization of subcellular organelles upon photoirradiation, causing superior photothermal tumor regress. The micelles act as a powerful theranostic nanocarrier for simultaneous cancer imaging with high contrast and superior photothermal therapy.

  18. Small angle neutron scattering study of doxorubicin–surfactant complexes encapsulated in block copolymer micelles

    Indian Academy of Sciences (India)

    Jayita Bhattacharjee; Gunjan Verma; V K Aswal; P A Hassan

    2008-11-01

    Self-assembling behaviour of block copolymers and their ability to evade the immune system through polyethylene oxide stealth makes it an attractive candidate for drug encapsulation. Micelles formed by polyethylene oxide–polypropylene oxide–polyethylene oxide triblock copolymers (PEO–PPO–PEO), pluronic P123, have been employed for encapsulating the anti-cancer drug doxorubicin hydrochloride. 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 the anti-cancer drug into nonpolar solvents such as chloroform is investigated. SANS measurements were performed on pluronic P123 mi-celles in the presence of drug–surfactant complex. No significant changes in the structure of the micelles are observed upon drug encapsulation. This demonstrates that surfactant–drug complexes can be encapsulated in block copolymer micelles without disrupting the structure of aggregates.

  19. Thermal deactivation kinetics of Pseudomonas fluorescens lipase entrapped in AOT/isooctane reverse micelles.

    Science.gov (United States)

    Park, Kyung Min; Kwon, Chang Woo; Choi, Seung Jun; Son, Young-Hwan; Lim, Seokwon; Yoo, Yoonjung; Chang, Pahn-Shick

    2013-10-02

    Thermostability of the lipase (EC 3.1.1.3) was found to be increased by the enzyme-entrapment in 50 mM AOT/isooctane reverse micelles. The half-life (15.75 h) of Pseudomonas fluorescens lipase entrapped in reverse micelles at 70 °C was 9.72- and 11.41-fold longer than those solubilized in a glycerol pool or in 10 mM phosphate buffer (pH 8.0), respectively. The enzyme deactivation model considering a two-step series-type was employed, and deactivation constants for the second step (k₂) at all temperatures were drastically decreased after the lipase was entrapped in reverse micelles. In particular, k₂ (0.0354 h⁻¹) at 70 °C in reverse micelles was 12.33- and 13.14-fold lower than in a glycerol pool or in the phosphate buffer, respectively. The deactivation energies (from k₁, k₂) for the lipase entrapped in the reverse micelles, solubilized in a glycerol pool, or in the aqueous buffer were 7.51, 26.35 kcal/mol, 5.93, 21.08 kcal/mol, and 5.53, 17.57 kcal/mol, respectively.

  20. Reverse micelles: inert nano-reactors or physico-chemically active guides of the capped reactions.

    Science.gov (United States)

    Uskoković, Vuk; Drofenik, Miha

    2007-05-31

    Reverse micelles present self-assembled multi-molecular entities formed within specific compositional ranges of water-in-oil microemulsions. The structure of a reverse micelle is typically represented as nano-sized droplet of a polar liquid phase, capped by a monolayer of surfactant molecules, and uniformly distributed within a non-polar, oil phase. Although their role in serving as primitive membranes for encapsulation of primordial self-replicating chemical cycles that anticipated the very origins of life has been proposed, their first application for 'parent(hesis)ing' chemical reactions with an aim to produce 'templated' 2D arrays of nanoparticles dates back to only 25 years ago. Reverse micelles have since then been depicted as passive nano-reactors that via their shapes template the growing crystalline nuclei into narrowly dispersed or even perfectly uniform nano-sized particles. Despite this, numerous examples can be supported, where from deviations from the simple unilateral correlations between size and shape distribution of reverse micelles and the particles formed within may be reasonably implied. A rather richer, dynamical role of reverse micelles, with potential significance in the research and design of complex, self-assembly synthesis pathways, as well as possible adoption of their application as an aspect of biomimetic approach, is suggested herein.

  1. H2S-Releasing Polymer Micelles for Studying Selective Cell Toxicity.

    Science.gov (United States)

    Foster, Jeffrey C; Radzinski, Scott C; Zou, Xianlin; Finkielstein, Carla V; Matson, John B

    2017-04-03

    We report the preparation of S-aroylthiooxime (SATO) functionalized amphiphilic block copolymer micelles that release hydrogen sulfide (H2S), a gaseous signaling molecule of relevance to various physiological and pathological conditions. The micelles release H2S in response to cysteine with a half-life of 3.3 h, which is substantially slower than a related small molecule SATO. Exogenous administration of H2S impacts growth and proliferation of cancer cells; however, the limited control over H2S generation from inorganic sulfide sources results in conflicting reports. Therefore, we compare the cellular cytotoxicity of SATO-functionalized micelles, which release H2S in a sustained manner, to Na2S, which releases H2S in a single dose. Our results show that H2S-releasing micelles significantly reduce the survival of HCT116 colon cancer cells relative to Na2S, GYY4137, and a small molecule SATO, indicating that release kinetics may play an important role in determining toxicity of H2S toward cancer cells. Furthermore, H2S-releasing micelles are well tolerated by immortalized fibroblasts (NIH/3T3 cells), suggesting a selective toxicity of H2S toward cancer cells.

  2. Biodegradable stereocomplex micelles based on dextran-block-polylactide as efficient drug deliveries.

    Science.gov (United States)

    Zhao, Ziwei; Zhang, Zhe; Chen, Li; Cao, Yue; He, Chaoliang; Chen, Xuesi

    2013-10-22

    Biodegradable stereocomplex micelles (SCMs) based on amphiphilic dextran-block-polylactide (Dex-b-PLA) were designed and used for efficient intracellular drug deliveries. The Dex-b-PLA copolymers were successfully synthesized by click reaction. The structures of the resultant copolymers were verified by (1)H NMR and FT-IR spectra. The formation of stable micelles through self-assembly driven by the stereocomplexation between enantiomeric l- and d-PLA blocks was characterized by transmission electron microscopy (TEM), dynamic laser scattering (DLS), and fluorescence techniques. It was interesting to observe that the SCMs showed lower critical micelle concentration values (CMCs) because of the stereocomplex interaction between PLLA and PDLA. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis provided information on the thermal and crystal properties of the copolymers and SCMs. The improved stability of SCMs should be attractive for intracellular drug delivery. Thus, a model anticancer drug doxorubicin (DOX) was loaded into micelles, and the in vitro drug release in was also studied. The release kinetics of DOX showed DOX-loaded SCMs exhibited slower DOX release. Confocal laser scanning microscopy (CLSM) and flow cytometry studies also showed that the DOX-loaded SCMs exhibited a slower drug release behavior. Meanwhile, the MTT assay demonstrated that DOX-loaded SCMs show lower cellular proliferation inhibition against HepG2. In sum, the micelles through self-assembly driven by stereocomplex interaction would have great potential to be used as stable delivery vehicles for pharmaceutical and biomedical applications.

  3. Electrical conductivity study on micelle formation of long-chain imidazolium ionic liquids in aqueous solution.

    Science.gov (United States)

    Inoue, Tohru; Ebina, Hayato; Dong, Bin; Zheng, Liqiang

    2007-10-01

    Electrical conductivity was measured for aqueous solutions of long-chain imidazolium ionic liquids (IL), 1-alkyl-3-methylimidazolium bromides with C(12)-C(16) alkyl chains. The break points appeared in specific conductivity (kappa) vs concentration (c) plot indicates that the molecular aggregates, i.e., micelles, are formed in aqueous solutions of these IL species. The critical micelle concentration (cmc) determined from the kappa vs c plot is somewhat lower than those for typical cationic surfactants, alkyltrimethylammonium bromides with the same hydrocarbon chain length. The electrical conductivity data were analyzed according to the mixed electrolyte model of micellar solution, and the aggregation number, n, and the degree of counter ion binding, beta, were estimated. The n values of the present ILs are somewhat smaller than those reported for alkyltrimethylammonium bromides, which may be attributed to bulkiness of the cationic head group of the IL species. The thermodynamic parameters for micelle formation of the present ILs were estimated using the values of cmc and beta as a function of temperature. The contribution of entropy term to the micelle formation is superior to that of enthalpy term below about 30 degrees C, and it becomes opposite at higher temperature. This coincides with the picture drawn for the micelle formation of conventional ionic surfactants.

  4. Too Much Sodium

    Centers for Disease Control (CDC) Podcasts

    2012-02-07

    This podcast is based on the February 2012 CDC Vital Signs report. Ninety percent of Americans age two and older eat too much sodium which can increase your risk for high blood pressure and often leads to heart disease and stroke, two leading causes of death in the US. Learn several small steps you can take to reduce the amount of sodium in your diet.  Created: 2/7/2012 by Centers for Disease Control and Prevention (CDC).   Date Released: 2/7/2012.

  5. DEVELOPMENT OF SEPARATION SYSTEMS FOR POLYNUCLEAR AROMATIC HYDROCARBON ENVIRONMENTAL CONTAMINANTS USING MICELLAR ELECTROKINETIC CHROMATOGRAPHY WITH MOLECULAR MICELLES AND FREE ZONE ELECTROPHORESIS

    Science.gov (United States)

    Of four systems available from the literature, based on cyclodextrins, dioctylsulfosuccinate, bile salts, and molecular micelles consisting of oligomers of undecylenic acid, the most successful separation system in our hands is based on the molecular micelles, oligomers of sodiu...

  6. Complex coacervate core micelles with a lysozyme-modified corona.

    Science.gov (United States)

    Danial, Maarten; Klok, Harm-Anton; Norde, Willem; Stuart, Martien A Cohen

    2007-07-17

    This paper describes the preparation, characterization, and enzymatic activity of complex coacervate core micelles (C3Ms) composed of poly(acrylic acid) (PAA) and poly(N-methyl-2-vinyl pyridinium iodide)-b-poly(ethylene oxide) (PQ2VP-PEO) to which the antibacterial enzyme lysozyme is end-attached. C3Ms were prepared by polyelectrolyte complex formation between PAA and mixtures containing different ratios of aldehyde and hydroxyl end-functionalized PQ2VP-PEO. This resulted in the formation of C3Ms containing 0-40% (w/w) of the aldehyde end-functionalized PQ2VP-PEO block copolymer (PQ2VP-PEO-CHO). Chemical conjugation of lysozyme was achieved via reductive amination of the aldehyde groups, which are exposed at the surface of the C3M, with the amine groups present in the side chains of the lysine residues of the protein. Dynamic and static light scattering indicated that the conjugation of lysozyme to C3Ms prepared using 10 and 20% (w/w) PQ2VP-PEO-CHO resulted in the formation of unimicellar particles. Multimicellar aggregates, in contrast, were obtained when lysozyme was conjugated to C3Ms prepared using 30 or 40% (w/w) PQ2VP-PEO-CHO. The enzymatic activity of the unimicellar lysozyme-C3M conjugates toward the hydrolysis of the bacterial substrate Micrococcus lysodeikticus was comparable to that of free lysozyme. For the multimicellar particles, in contrast, significantly reduced enzymatic rates of hydrolysis, altered circular dichroism, and red-shifted tryptophan fluorescence spectra were measured. These results are attributed to the occlusion of lysozyme in the interior of the multimicellar conjugates.

  7. pH-Responsive Hyaluronic Acid-Based Mixed Micelles for the Hepatoma-Targeting Delivery of Doxorubicin

    Directory of Open Access Journals (Sweden)

    Jing-Liang Wu

    2016-03-01

    Full Text Available The tumor targetability and stimulus responsivity of drug delivery systems are crucial in cancer diagnosis and treatment. In this study, hepatoma-targeting mixed micelles composed of a hyaluronic acid–glycyrrhetinic acid conjugate and a hyaluronic acid-l-histidine conjugate (HA–GA/HA–His were prepared through ultrasonic dispersion. The formation and characterization of the mixed micelles were confirmed via 1H-NMR, particle size, and ζ potential measurements. The in vitro cellular uptake of the micelles was evaluated using human liver carcinoma (HepG2 cells. The antitumor effect of doxorubicin (DOX-loaded micelles was investigated in vitro and in vivo. Results indicated that the DOX-loaded HA–GA/HA–His micelles showed a pH-dependent controlled release and were remarkably absorbed by HepG2 cells. Compared with free DOX, the DOX-loaded HA–GA/HA–His micelles showed a higher cytotoxicity to HepG2 cells. Moreover, the micelles effectively inhibited tumor growth in H22 cell-bearing mice. These results suggest that the HA–GA/HA–His mixed micelles are a good candidate for drug delivery in the prevention and treatment of hepatocarcinoma.

  8. Thermo-responsive shell cross-linked PMMA-b-P(NIPAAm-co-NAS) micelles for drug delivery.

    Science.gov (United States)

    Chang, Cong; Wei, Hua; Wu, De-Qun; Yang, Bin; Chen, Ni; Cheng, Si-Xue; Zhang, Xian-Zheng; Zhuo, Ren-Xi

    2011-11-28

    Thermo-responsive amphiphilic poly(methyl methacrylate)-b-poly(N-isopropylacrylamide-co-N-acryloxysuccinimide) (PMMA-b-P(NIPAAm-co-NAS)) block copolymer was synthesized by successive RAFT polymerizations. The uncross-linked micelles were facilely prepared by directly dissolving the block copolymer in an aqueous medium, and the shell cross-linked (SCL) micelles were further fabricated by the addition of ethylenediamine as a di-functional cross-linker into the micellar solution. Optical absorption measurements showed that the LCST of uncross-linked and cross-linked micelles was 31.0°C and 40.8°C, respectively. Transmission electron microscopy (TEM) showed that both uncross-linked and cross-linked micelles exhibited well-defined spherical shape in aqueous phase at room temperature, while the SCL micelles were able to retain the spherical shape with relatively smaller dimension even at 40°C due to the cross-linked structure. In vitro drug release study demonstrated a slower and more sustained drug release behavior from the SCL micelles at high temperature as compared with the release profile of uncross-linked micelles, indicating the great potential of SCL micelles developed herein as novel smart carriers for controlled drug release.

  9. Preparation of core-crosslinked linear-dendritic copolymer micelles with enhanced stability and their application for drug solubilisation.

    Science.gov (United States)

    Zhou, Zhengyuan; Forbes, Robert T; D'Emanuele, Antony

    2017-05-15

    In this study we explore the preparation of core-crosslinked micelles of linear-dendritic methoxy-poly(ethylene glycol) (MPEG)-co-poly(ester-sulfide) (PES) polymers to improve the stability of such polymeric micelle systems against premature disintegration and drug release. A series of MPEG-PES copolymers were synthesised via stepwise reactions of acetylation and thiol-ene photoreaction. Surface tension measurement showed that the copolymers with ethenyl surface groups could self-associate in dilute aqueous solutions to form micelles. Crosslinking within the micelle cores in the presence of dithioerythritol (DTT) linker was initiated under UV radiation. The formation of core-crosslinked micelles was confirmed by HPLC in combination with charged aerosol detection (CAD). The copolymers were found to readily hydrolyse under acidic conditions due to the ester-containing dendrons. Drug solubilisation capacities of the micellar solutions were determined using griseofulvin as a poorly water-soluble model drug. The solubility of griseofulvin showed a 10-fold enhancement in 1% w/v micelle solution and increased with the concentration of the copolymers. Drug release studies indicated that a more sustained release of griseofulvin was achieved for the core-crosslinked micelles compared to the non-crosslinked micelles, attributable to greater stability of the crosslinked core structure. The findings of this study present a new pathway towards developing biodegradable polymeric nanocarriers. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Doxorubicin-mediated radiosensitivity in multicellular spheroids from a lung cancer cell line is enhanced by composite micelle encapsulation

    Science.gov (United States)

    Xu, Wen-Hong; Han, Min; Dong, Qi; Fu, Zhi-Xuan; Diao, Yuan-Yuan; Liu, Hai; Xu, Jing; Jiang, Hong-Liang; Zhang, Su-Zhan; Zheng, Shu; Gao, Jian-Qing; Wei, Qi-Chun

    2012-01-01

    Background The purpose of this study is to evaluate the efficacy of composite doxorubicinloaded micelles for enhancing doxorubicin radiosensitivity in multicellular spheroids from a non-small cell lung cancer cell line. Methods A novel composite doxorubicin-loaded micelle consisting of polyethylene glycolpolycaprolactone/Pluronic P105 was developed, and carrier-mediated doxorubicin accumulation and release from multicellular spheroids was evaluated. We used confocal laser scanning microscopy and flow cytometry to study the accumulation and efflux of doxorubicin from A549 multicellular spheroids. Doxorubicin radiosensitization and the combined effects of irradiation and doxorubicin on cell migration and proliferation were compared for the different doxorubicin delivery systems. Results Confocal laser scanning microscopy and quantitative flow cytometry studies both verified that, for equivalent doxorubicin concentrations, composite doxorubicin-loaded micelles significantly enhanced cellular doxorubicin accumulation and inhibited doxorubicin release. Colony-forming assays demonstrated that composite doxorubicin-loaded micelles are radiosensitive, as shown by significantly reduced survival of cells treated by radiation + composite micelles compared with those treated with radiation + free doxorubicin or radiation alone. The multicellular spheroid migration area and growth ability verified higher radiosensitivity for the composite micelles loaded with doxorubicin than for free doxorubicin. Conclusion Our composite doxorubicin-loaded micelle was demonstrated to have radiosensitization. Doxorubicin loading in the composite micelles significantly increased its cellular uptake, improved drug retention, and enhanced its antitumor effect relative to free doxorubicin, thereby providing a novel approach for treatment of cancer. PMID:22679376

  11. Pluronic-poly (acrylic acid)-cysteine/Pluronic L121 mixed micelles improve the oral bioavailability of paclitaxel.

    Science.gov (United States)

    Zhao, Yanli; Li, Yanli; Ge, Jianjun; Li, Na; Li, Ling-Bing

    2014-11-01

    The aim of the study is to synthesize a thiolated Pluronic copolymer, Pluronic-poly (acrylic acid)-cysteine copolymer, to construct a mixed micelle system with the Pluronic-poly (acrylic acid)-cysteine copolymer and Pluronic L121 (PL121) and to evaluate the potential of these mixed micelles as an oral drug delivery system for paclitaxel. Compared with Pluronic-poly (acrylic acid)-cysteine micelles, drug-loading capacity of Pluronic-poly (acrylic acid)-cysteine/PL121 mixed micelles was increased from 0.4 to 2.87%. In vitro release test indicated that Pluronic-poly (acrylic acid)-cysteine/PL121 mixed micelles exhibited a pH sensitivity. The permeability of drug-loaded micelles in the intestinal tract was studied with an in situ perfusion method in rats. The presence of verapamil and Pluronic both improved the intestinal permeability of paclitaxel, which further certified the inhibition effect of thiolated Pluronic on P-gp. In pharmacokinetic study, the area under the plasma concentration-time curve (AUC0→∞) of paclitaxel-loaded mixed micelles was four times greater than that of the paclitaxel solution (p cysteine/PL121 micelles were proven to be a potential oral drug delivery system for paclitaxel.

  12. Enhanced effect in combination of curcumin- and ketoconazole-loaded methoxy poly (ethylene glycol)-poly (ε-caprolactone) micelles.

    Science.gov (United States)

    Teng, Fangfang; Deng, Peizong; Song, Zhimei; Zhou, Feilong; Feng, Runliang

    2017-04-01

    In order to enhance water-solubility and realize controlled release while keeping synergistic effects of ketoconazole and curcumin, drug-loaded methoxy poly (ethylene glycol)-b-poly (ε-caprolactone) micelles were prepared through thin membrane hydration method. Transmission electric microscopy and dynamitic light scattering characterization revealed the formation of ketoconazole- and curcumin-loaded micelles with an average size of 44.70nm and 39.56nm, respectively. The drug-loaded micelles endowed the two drugs' slow controlled release with water-solubility enhanced to 85 and 82000 folds higher than the corresponding raw drugs, respectively. In vitro antifungal activity test, chequerboard test and inhibition zone test indicated that efficacy of ketoconazole-loaded micelles was improved by introduction of curcumin-loaded micelles with a low fractional inhibitory concentration index (0.073). Biofilm formation inhibition assay also demonstrated that participation of curcumin-loaded micelles obviously strengthened the inhibition of fungal biofilms formation induced by ketoconazole-loaded micelles. The high synergistic activity of combinations is encouraging and the MPEG-PCL micelle is a potential drug delivery system for the combination of ketoconazole and curcumin. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  13. Photothermal Ablation of in Situ Renal Tumor by PEG-IR780-C13 Micelles and Near-Infrared Irradiation.

    Science.gov (United States)

    Qiu, Xuefeng; Xu, Linfeng; Zhang, Yanting; Yuan, Ahu; Wang, Kaikai; Zhao, Xiaozhi; Wu, Jinhui; Guo, Hongqian; Hu, Yiqiao

    2016-03-07

    PEG-IR780-C13 micelles have been demonstrated to be a novel photothermal agent with tumor-targeting property. This study was designed to explore the feasibility of applying PEG-IR780-C13 micelles and near-infrared (NIR) irradiation for thermal ablation of renal tumor by using an in situ tumor model. In addition, the potential thermal injury to normal renal tissue was evaluated. PEG-IR780-C13 micelles were intended to accumulate in renal tumor after systemic delivery. In vitro results revealed that PEG-IR780-C13 micelles were uptaken by RENCA cells mainly through caveola-mediated endocytosis and mainly distributed in late endosomes and lysosomes. Upon NIR irradiation, PEG-IR780-C13 micelles generated heat effectively both in vitro and in vivo, exhibiting a promising photothermal therapeutic property. The photothermal effect of PEG-IR780-C13 micelles could effectively destroy RENCA cells in vitro and adequately inhibit growth of in situ renal tumor in vivo. Meanwhile, PEG-IR780-C13 micelles mediated photothermal therapy (PTT) resulting in only limited injury to normal renal tissue surrounding tumor sites. Our data indicated that PEG-IR780-C13 micelles mediating PTT could generate tumor-specific heat for destruction of renal tumor in a minimally invasive way, providing a novel strategy for thermal ablation of renal tumor.

  14. Cardiac sodium channelopathies

    NARCIS (Netherlands)

    Amin, A.S.; Asghari-Roodsari, A.; Tan, H.L.

    2010-01-01

    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (I-Na) during phase 0 of the cardiac action potential. The importance of I-Na for normal cardiac electrical activity is reflected by the high incidence of

  15. Cardiac sodium channelopathies

    NARCIS (Netherlands)

    Amin, A.S.; Asghari-Roodsari, A.; Tan, H.L.

    2010-01-01

    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (I-Na) during phase 0 of the cardiac action potential. The importance of I-Na for normal cardiac electrical activity is reflected by the high incidence of

  16. Sodium fluxes in sweet pepper exposed to varying sodium concentrations

    NARCIS (Netherlands)

    Blom-Zandstra, M.; Vogelzang, S.A.; Veen, B.W.

    1998-01-01

    The sodium transport and distribution of sweet pepper (Capsicum annuum L.) under saline conditions were studied after transferring the plants to a sodium-free nutrient solution. Sodium stress up to 60 mM did not affect the growth of sweet pepper, as it appears able to counteract the unfavourable phy

  17. Sodium fluxes in sweet pepper exposed to varying sodium concentrations

    NARCIS (Netherlands)

    Blom-Zandstra, M.; Vogelzang, S.A.; Veen, B.W.

    1998-01-01

    The sodium transport and distribution of sweet pepper (Capsicum annuum L.) under saline conditions were studied after transferring the plants to a sodium-free nutrient solution. Sodium stress up to 60 mM did not affect the growth of sweet pepper, as it appears able to counteract the unfavourable

  18. Reverse micelles extraction of nattokinase: From model system to real system

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nattokinase is a novel fibrinolytic enzyme, which is homologous to Subtilisin Carlsberg. In this paper, Subtilisin Carlsberg was taken as a model protein of nattokinase. Effects of pH, ionic strength, concentration of isopropanol on the extraction of Subtilisin Carlsberg with AOT/isooctane reverse micelles system were investigated. Further, the process of reverse micelles extraction of nattokinase from fermentation broth was studied. By taking the reverse micelles of AOT/isooctane as extractant to perform a full extraction cycle, it was found that about eighty percent of the total activity of nattokinase in the fermentation broth could be recovered and the purification factor was about 2.5. Homologous protein could be reasonably used as model protein of a target protein.

  19. Polymerization of o-Phenylenediamine Catalyzed by Hemeproteins Encapsulated in Reversed Micelle

    Institute of Scientific and Technical Information of China (English)

    YANG Yong; MAO Lu-yuan; LI Liu-zhu; LIU Xiao-guang; SHI Jun; CAO Shao-kui

    2004-01-01

    Hemeproteins encapsulated in reversed micelle formulated with di-2-ethylhexyl sulfosuccinate (AOT)was found to catalyze the polymerization of o-phenylenediamine (o-PDA) with hydrogen peroxide, whereas o-PDA catalyzed by hemeproteins dissolved in water could only form its trimers. As the nanostructural environment in reversed micelle acts as a certain orientation surrounding medium, it offers a strong electrostatic field that alters the reductive potential of Fe3+/Fe2+ (Em7) in the heme of hemeproteins and thus increases the catalytic activity of peroxidase accordingly. According to the results of UV-Vis, 1H NMR and FTIR, the polymer catalyzed by hemoglobin(Hb) in reversed micelle was presumed to be constructed of lines and trapeziforms alternatively.

  20. Bile Salt Micelles and Phospholipid Vesicles Present in Simulated and Human Intestinal Fluids

    DEFF Research Database (Denmark)

    Elvang, Philipp A; Hinna, Askell H; Brouwers, Joachim

    2016-01-01

    Knowledge about colloidal assemblies present in human intestinal fluids (HIFs), such as bile salt micelles and phospholipid vesicles, is regarded of importance for a better understanding of the in vivo dissolution and absorption behavior of poorly soluble drugs (Biopharmaceutics Classification...... distinct size fraction of colloidal assemblies, whereas FeSSIF contained 2 fractions of colloidal species with significantly different sizes. These size fractions likely represent (1) mixed taurocholate-phospholipid-micelles, as indicated by a size range up to 70 nm (in diameter) and a strong UV absorption...... sizes of approximately 50 and 200 nm, respectively (intensity-weighted mean diameter, Dz), likely representing mixed cholate/phospholipid micelles and phospholipid vesicles, respectively. The sizes of the smaller 2 fractions being below the size range of multiangle laser light scattering analysis (