WorldWideScience

Sample records for dna-based micelles synthesis

  1. Synthesis and immobilization of polystyreneb-polyvinyltriethoxysilane micelles

    KAUST Repository

    Zhu, Saisai

    2018-01-31

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

  2. 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).

  3. Synthesis and agglomeration of gold nanoparticles in reverse micelles

    Science.gov (United States)

    Herrera, Adriana P.; Resto, Oscar; Briano, Julio G.; Rinaldi, Carlos

    2005-07-01

    Reverse micelles prepared in the system water, sodium bis-(2-ethylhexyl) sulfoccinate (AOT), and isooctane were investigated as a templating system for the production of gold nanoparticles from Au(III) and the reducing agent sulfite. A core-shell Mie model was used to describe the optical properties of gold nanoparticles in the reverse micelles. Dynamic light scattering of gold colloids in aqueous media and in reverse micelle solution indicated agglomeration of micelles containing particles. This was verified theoretically with an analysis of the total interaction energy between pairs of particles as a function of particle size. The analysis indicated that particles larger than about 8 nm in diameter should reversibly flocculate. Transmission electron microscopy measurements of gold nanoparticles produced in our reverse micelles showed diameters of 8-10 nm. Evidence of cluster formation was also observed. Time-correlated UV-vis absorption measurements showed a red shift for the peak wavelength. This was interpreted as the result of multiple scattering and plasmon interaction between particles due to agglomeration of micelles with particles larger than 8 nm.

  4. Synthesis and Characterization of a Micelle-Based pH Nanosensor with an Unprecedented Broad Measurement Range

    DEFF Research Database (Denmark)

    Ek, Pramod Kumar; Feldborg, Lise N.; Almdal, Kristoffer

    2013-01-01

    A new cross-linked micelle pH nanosensor design was investigated. The nanosensor synthesis was based on self-assembly of an amphiphilic triblock copolymer, poly(ethylene glycol)-b-poly(2-amino ethyl methacrylate)-b-poly(coumarin methacrylate) (PEG-b-PAEMA-b-PCMA), which was synthesized by isolated...... macroinitiator atom transfer radical polymerization. Micelles were formed by PEG-b-PAEMA-b-PCMA self-assembly in water, giving micelles with an average diameter of 45 nm. The PCMA core was employed to utilize coumarin-based photoinduced cross-linking in the core of the micelles, which was performed by UV...

  5. pH and thermo-responsive tetronic micelles for the synthesis of gold nanoparticles: effect of physiochemical aspects of tetronics.

    Science.gov (United States)

    Singh, Vijender; Khullar, Poonam; Dave, Pragnesh N; Kaura, Aman; Bakshi, Mandeep Singh; Kaur, Gurinder

    2014-03-14

    Micelles of the star shaped block polymers "tetronics" were employed for the synthesis of gold (Au) nanoparticles (NPs) under the effect of pH and temperature variation. The presence of the diamine core in the tetronic macromolecule made its micelles highly pH responsive, thereby dramatically altering the physiochemical properties. Likewise, a high degree of hydration made the micelles temperature sensitive. UV-visible studies, transmission electron microscopy (TEM), gel electrophoresis, and structure optimization by energy minimization were applied to understand the physiochemical aspects of tetronic micelles and their further role in the synthesis of Au NPs. Synthesis of Au NPs was triggered by the surface cavities of the micelles and hence the NPs simultaneously adsorbed on the micelle surface. Low pH induced high hydration and temperature responsive well defined vesicular morphologies bearing Au NPs, while high pH produced mainly large and compact compound micelles carrying NPs. Both pH and temperature responsive behaviors of different tetronics significantly influenced the synthesis of Au NPs and thus demonstrated their ability to act as nanoreactors for the materials synthesis under different experimental conditions.

  6. Synthesis and Characterization of SPIO-loaded PEG-b-PS Micelles ...

    Indian Academy of Sciences (India)

    66

    size of SPIO cluster. However, the relaxivity reaches its maximum in the static dephasing regime (SDR); then, it decreased with increasing clustering size in the echo-limiting regime. (ELR). SPIO loaded PEG-b-PS micelles presented similar phenomena in MAR. The r2* values were linearly increased by the size of micelles ...

  7. 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...

  8. Micelles of poly(styrene-b-2-vinylpyridine-b-ethylene oxide) with blended polystyrene core and their application to the synthesis of hollow silica nanospheres.

    Science.gov (United States)

    Liu, Dian; Sasidharan, Manickam; Nakashima, Kenichi

    2011-06-15

    Core-shell-corona (CSC) micelles of asymmetric triblock copolymer, poly(styrene-b-2-vinylpyridine-b-ethylene oxide) (PS-PVP-PEO), containing polystyrene homopolymer (homo-PS) in the core were successfully prepared in aqueous media. The influence of homo-PS contents over the formation of the micelles was investigated thoroughly by various techniques such as dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fluorescence spectroscopy. It was found that the size of the PS core of the micelle was increased by the addition of homo-PS as observed by DLS and TEM techniques. The SEM and TEM measurements confirm the spherical morphology of the micelles and enlargement of PS core over the addition of homo-PS. The increase in the PS core volume of the PS-PVP-PEO micelles is attributed to the insertion of homo-PS in the PS core. The micelles have also been demonstrated as facile soft templates for synthesis of hollow silica nanospheres. The average diameter of the spherical hollow particles could be tuned between 30.6 and 38.8 nm with cavity sizes ranging from 20.7 to 28.5 nm using tetramethoxysilane as silica precursors under mild acidic conditions. The facile synthesis of hollow silica using the CSC micelles with different homo-PS contents indicates that the hollow void size can be controlled within a range of several nanometers. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Redox-sensitive Pluronic F127-tocopherol micelles: synthesis, characterization, and cytotoxicity evaluation

    Directory of Open Access Journals (Sweden)

    Liu Y

    2017-04-01

    Full Text Available Yuling Liu,1,2,* Sai Fu,1,* Longfei Lin,1 Yuhong Cao,3 Xi Xie,3 Hua Yu,2 Meiwan Chen,2 Hui Li1 1Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 2State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau, People’s Republic of China; 3Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA *These authors contributed equally to the work Abstract: Pluronic F127 (F127, an amphiphilic triblock copolymer, has been shown to have significant potential for drug delivery, as it is able to incorporate hydrophobic drugs and self-assemble into nanosize micelles. However, it suffers from dissociation upon dilution owing to the relatively high critical micelle concentration and lack of stimuli-responsive behavior. Here, we synthesized the α-tocopherol (TOC modified F127 polymer (F127-SS-TOC via a redox-sensitive disulfide bond between F127 and TOC, which formed stable micelles at relatively low critical micelle concentration and was sensitive to the intracellular redox environment. The particle size and zeta potential of the F127-SS-TOC micelles were 51.87±6.39 nm and -8.43±2.27 mV, respectively, and little changes in both particle size and zeta potential were observed within 7 days at room temperature. With 10 mM dithiothreitol stimulation, the F127-SS-TOC micelles rapidly dissociated followed by a significant change in size, which demonstrated a high reduction sensitivity of the micelles. In addition, the micelles showed a high hemocompatibility even at a high micelle concentration (1,000 µg/mL. Low cytotoxicity of the F127-SS-TOC micelles at concentrations ranging from 12.5 µg/mL to 200 µg/mL was also found on both Bel 7402 and L02 cells. Overall, our results demonstrated F127-SS-TOC micelles as a stable and safe aqueous formulation with a considerable potential for drug delivery. Keywords: Pluronic F127

  10. Design, synthesis and evaluation of biotin decorated inulin-based polymeric micelles as long-circulating nanocarriers for targeted drug delivery.

    Science.gov (United States)

    Mandracchia, Delia; Rosato, Antonio; Trapani, Adriana; Chlapanidas, Theodora; Montagner, Isabella Monia; Perteghella, Sara; Di Franco, Cinzia; Torre, Maria Luisa; Trapani, Giuseppe; Tripodo, Giuseppe

    2017-04-01

    Here, long-circulating behaviors of Inulin-based nanomicelles are demonstrated for the first time in vivo. We show the synthesis and evaluation of biotin (BIO)-decorated polymeric INVITE micelles constituted of substances of natural origin, Inulin (INU) and Vitamin E (VITE), as long-circulating carriers for receptor-mediated targeted drug delivery. The resulting INVITE or INVITE-BIO micelles, nanometrically sized, did not reveal any cytotoxicity after 24h of incubation with Caco-2 cells. Moreover, in vitro studies on Caco-2 cells monolayers indicated that the transport of INVITE-BIO micelles was faster than surface unmodified INVITE micelles. In vivo optical imaging studies evidenced that, upon intravenous administration, INVITE-BIO micelles were quantitatively present in the body up to 48h. Instead, after oral administration, the micelles were not found in the systemic circulation but eliminated with the normal intestinal content. In conclusion, INVITE-BIO micelles may enhance drug accumulation in tumor-cells over-expressing the receptor for biotin through receptor mediated endocytosis. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Synthesis and characterization of SPIO-loaded PEG-b-PS micelles ...

    Indian Academy of Sciences (India)

    2018-03-27

    Mar 27, 2018 ... This formulation showed stability over a 10-week period, and the standard deviations of the relaxivities were. 3.0 and 8.0% for 1.5 and 3 T MRI, respectively. Thus, SPIO-loaded PEG-b-PS micelles have a potential to be applied as a contrast agent for nanoparticle-based MRI phantom. Keywords. Iron oxide ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-31

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

  13. 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

  14. Synthesis and characterization of an amphiphilic cyclodextrin, a micelle with two recognition sites.

    Science.gov (United States)

    Silva, O Fernando; Fernández, Mariana A; Pennie, Sarah L; Gil, Roberto R; de Rossi, Rita H

    2008-04-15

    A cyclodextrin derivative (Mod-CD) was synthesized through the monoesterification of beta-cyclodextrin (beta-CD) with 3-((E)-dec-2-enyl)-dihydrofuran-2,5-dione. The compound is an interesting surfactant that can form large aggregates not only through the interaction of the hydrophobic tails as in common amphiphilic compounds but also through the inclusion of the alkenyl chain into the cavity of another Mod-CD molecule. The self-inclusion of the chain in the cavity of cyclodextrin as well as the intermolecular inclusion was demonstrated by 1H NMR measurements that were able to detect methyl groups in three different environments. Besides, in the aggregates of Mod-CD, the cavity is available to interact with external guests such as phenolphthalein, 1-amino adamantane, and Prodan. Phenolphthalein has the same binding constant with Mod-CD and beta-CD, but the equilibrium constant for the interaction with Prodan is about 2 times larger for Mod-CD than for beta-CD. The latter result is attributed to the fact that this probe interacts with the micelle in two binding sites: the cavity of the cyclodextrin and the apolar heart of the micelle as evidenced by the spectrofluorimetric behavior of Prodan in solutions containing different concentrations of Mod-CD.

  15. Synthesis of Titanium Dioxide nanoparticles via sucrose ester micelle-mediated hydrothermal processing route

    International Nuclear Information System (INIS)

    Anwar, N.S.; Kassim, A.; Lim, H.N.; Zakarya, S.A.; Huang, N.M.

    2010-01-01

    Titanium dioxide nanoparticles were synthesized via low-temperature sucrose ester micelle-mediated hydrothermal processing route using titanium isopropoxide as the precursor. X-ray diffractometer revealed that the samples possessed a mixed crystalline phases consisting of anatase and brookite in which anatase was the main phase. Upon increasing the hydrothermal reaction temperature, the degree of crystallinity of the nanoparticles improved and their morphology transformed from bundles of needles to rods and to spheres. Photo catalytic behaviour of the as-synthesized nanoparticles was investigated by photodegradation of methylene blue solution in an ultraviolet A irradiating photo reactor. The as-synthesized nanoparticles exhibited higher photo catalytic performance as compared to the commercial counterpart. (author)

  16. Thermal Decomposition Based Synthesis of Ag-In-S/ZnS Quantum Dots and Their Chlorotoxin-Modified Micelles for Brain Tumor Cell Targeting.

    Science.gov (United States)

    Chen, Siqi; Ahmadiantehrani, Mojtaba; Publicover, Nelson G; Hunter, Kenneth W; Zhu, Xiaoshan

    Cadmium-free silver-indium-sulfide (Ag-In-S or AIS) chalcopyrite quantum dots (QDs) as well as their core-shell structures (AIS/ZnS QDs) are being paid significant attention in biomedical applications because of their low toxicity and excellent optical properties. Here we report a simple and safe synthetic system to prepare high quality AIS and AIS/ZnS QDs using thermal decomposition. The synthetic system simply involves heating a mixture of silver acetate, indium acetate, and oleic acid in dodecanethiol at 170 °C to produce AIS QDs with a 13% quantum yield (QY). After ZnS shell growth, the produced AIS/ZnS QDs achieve a 41% QY. To facilitate phase transfer and bioconjugation of AIS/ZnS QDs for cellular imaging, these QDs were loaded into the core of PLGA-PEG (5k:5k) based micelles to form AIS/ZnS QD-micelles. Cellular imaging studies showed that chlorotoxin-conjugated QD-micelles can be specifically internalized into U-87 brain tumor cells. This work discloses that the scalable synthesis of AIS/ZnS QDs and the facile surface/interface chemistry for phase transfer and bioconjugation of these QDs may open an avenue for the produced QD-micelles to be applied to the detection of endogenous targets expressed on brain tumor cells, or more broadly to cell- or tissue-based diagnosis and therapy.

  17. Synthesis of nanosilver particles by reverse micelle method and study of their bactericidal properties

    Energy Technology Data Exchange (ETDEWEB)

    Tran Thi Ngoc Dung; Ngo Quoc Buu; Dang Viet Quang; Le Anh Bang; Nguyen Hoai Chau; Nguyen Thi Ly [Institute of Environmental Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay Distr., Hanoi (Viet Nam); Huynh Thi Ha [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay Distr., Hanoi (Viet Nam); Nguyen Vu Trung [National Institute for Infectious and Tropical Diseases, 1 Ton That Tung, Dong Da Distr., Hanoi (Viet Nam)], E-mail: ttndzung@yahoo.com, E-mail: buu_nq@yahoo.com

    2009-09-01

    Nanosilver particles have been synthesized by the reverse micelle method, where AgNO{sub 3} was used as a silver ions source, NaBH{sub 4} and quercetin - as reducing agents, CTAB, SDOSS and AOT- as surfactants, while the stabilizer was Vietnamese chitosan. Studying the factors influencing the process of nanosilver particle formation, it was shown that the particle size of the nanosilver products depends on the concentration of the reaction components and their stoichiometric ratio. It was also shown that the reaction system using AOT surfactant is capable of producing nanosilver particles with smallest nanoparticles ({phi}{sub av} {approx} 5 nm) and good particle-size distribution. The study on bactericidal activity of the nanosilver products indicated that the disinfecting solution with a nanosilver concentration of 3 ppm was able to inhibit all E.coli and Coliforms, TPC and fungi at 15 ppm, while Vibrio cholerae cells were inactivated completely with 0.5 ppm of nanosilver after 30 minutes exposition.

  18. Synthesis of in-situ luminescent ZnS nanoparticles facile with CTAB micelles and their properties study

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Vaishali [Centre for Nanoscience, Central University of Gujarat, Gandhinagar (India); Singh, Man [School of Chemical Sciences, Central University of Gujarat, Gandhinagar, India Telephone: 079-23260210, fax: 079-23260076 (India)

    2016-04-13

    Currently, the development of micelles route is thrust area of research in nanoscience for the control particle size and remarkable properties through chemical co-precipitation method. A 0.9 mM aqueous CTAB micellar solution plays a role as capping agent in the homogeneous solution of 0.5 M ZnSO{sub 4} and 0.5 M Na{sub 2}S for synthesis, further precipitates purified with centrifugation in cold ethanol and millipore water to remove unreacted reagents and ionic salt particles. A resultant, white colored luminescent ZnS nanoparticle out with ∼95% yield is reported. The ZnS nanoparticles have been examined by their luminescence properties, optical properties and crystal structure. The mean particle size of ZnS nanoparticles is found to be ∼10 nm in various technical results and UV-absorption was 80 nm blue shifts moved from 345 nm (bulk material) to 265 nm, showing a quantum size impact. The X-ray diffraction (XRD) pattern shows the immaculate cubic phase. Photoluminescence (PL) investigates the recombination mechanism with blue emission from shallow electron traps at 490 nm in ZnS nanoparticles. An FTIR spectrum and Thermal gravimetric analysis (TGA) gives confirmation of CTAB – cationic surfactant on surface of ZnS nanoparticle as capping agent as well thermal stability of CTAB capped ZnS nanoparticles with respect to temperature.

  19. Synthesis, characterisation, photo-physic and photochemistry properties of nanometer particles synthesised 'in situ' in reverse micelles

    International Nuclear Information System (INIS)

    Motte, Laurence

    1994-01-01

    This research thesis reports the use of inverse micelles as chemical micro-reactors for the synthesis of semiconductors of nano-metric size. The author first presents the properties of the inverse micellar system made of water, AOT and oil, and then describes electronic properties of semiconductors with respect to their size. After a bibliographical study on three semiconductors (CdS, AgI, Ag 2 S), the author highlights the presence of at least two types of water in the aqueous core of inverse micelles. She reports the study of the influence of the addition of a surfactant (CTAC, cetyl trimethyl ammonium chloride) on droplet properties, on the interaction between droplets, on reaction kinetics, and on crystallite size depending on the considered semiconductor (CdS, AgI or Ag 2 S) [fr

  20. DNA-based hybrid catalysis.

    Science.gov (United States)

    Rioz-Martínez, Ana; Roelfes, Gerard

    2015-04-01

    In the past decade, DNA-based hybrid catalysis has merged as a promising novel approach to homogeneous (asymmetric) catalysis. A DNA hybrid catalysts comprises a transition metal complex that is covalently or supramolecularly bound to DNA. The chiral microenvironment and the second coordination sphere interactions provided by the DNA are key to achieve high enantioselectivities and, often, additional rate accelerations in catalysis. Nowadays, current efforts are focused on improved designs, understanding the origin of the enantioselectivity and DNA-induced rate accelerations, expanding the catalytic scope of the concept and further increasing the practicality of the method for applications in synthesis. Herein, the recent developments will be reviewed and the perspectives for the emerging field of DNA-based hybrid catalysis will be discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Self-assembly of block copolymer micelles: synthesis via reversible addition-fragmentation chain transfer polymerization and aqueous solution properties.

    Science.gov (United States)

    Mya, Khine Y; Lin, Esther M J; Gudipati, Chakravarthy S; Gose, Halima B A S; He, Chaobin

    2010-07-22

    Poly(hexafluorobutyl methacrylate) (PHFBMA) homopolymer was synthesized by reversible addition-fragmentation chain transfer (RAFT)-mediated living radical polymerization in the presence of cyano-2-propyl dithiobenzoate (CPDB) RAFT agent. A block copolymer of PHFBMA-poly(propylene glycol acrylate) (PHFBMA-b-PPGA) with dangling poly(propylene glycol) (PPG) side chains was then synthesized by using CPDB-terminated PHFBMA as a macro-RAFT agent. The amphiphilic properties and self-assembly of PHFBMA-b-PPGA block copolymer in aqueous solution were investigated by dynamic and static light scattering (DLS and SLS) studies, in combination with fluorescence spectroscopy and transmission electron microscopy (TEM). Although PPG shows moderately hydrophilic character, the formation of nanosize polymeric micelles was confirmed by fluorescence and TEM studies. The low value of the critical aggregation concentration exhibited that the tendency for the formation of copolymer aggregates in aqueous solution was very high due to the strong hydrophobicity of the PHFBMA(145)-b-PPGA(33) block copolymer. The combination of DLS and SLS measurements revealed the existence of micellar aggregates in aqueous solution with an association number of approximately 40 +/- 7 for block copolymer micelles. It was also found in TEM observation that there are 40-50 micelles accumulated into one aggregate and these micelles are loosely packed inside the aggregate.

  2. Chiroplasmonic DNA-based nanostructures

    Science.gov (United States)

    Cecconello, Alessandro; Besteiro, Lucas V.; Govorov, Alexander O.; Willner, Itamar

    2017-09-01

    Chiroplasmonic properties of nanoparticles, organized using DNA-based nanostructures, have attracted both theoretical and experimental interest. Theory suggests that the circular dichroism spectra accompanying chiroplasmonic nanoparticle assemblies are controlled by the sizes, shapes, geometries and interparticle distances of the nanoparticles. In this Review, we present different methods to assemble chiroplasmonic nanoparticle or nanorod systems using DNA scaffolds, and we discuss the operations of dynamically reconfigurable chiroplasmonic nanostructures. The chiroplasmonic properties of the different systems are characterized by circular dichroism and further supported by high-resolution transmission electron microscopy or cryo-transmission electron microscopy imaging and theoretical modelling. We also outline the applications of chiroplasmonic assemblies, including their use as DNA-sensing platforms and as functional systems for information processing and storage. Finally, future perspectives in applying chiroplasmonic nanoparticles as waveguides for selective information transfer and their use as ensembles for chiroselective synthesis are discussed. Specifically, we highlight the upscaling of the systems to device-like configurations.

  3. Synthesis and characterization of erbium-doped SiO2 nanoparticles fabricated by using reverse micelle and sol-gel processing

    International Nuclear Information System (INIS)

    Park, Hoyyul; Bae, Dongsik

    2012-01-01

    Erbium-doped SiO 2 nanoparticles have been synthesized using a reverse micelle technique combined with metal-alkoxide hydrolysis and condensation. The sizes and the morphologies of the erbium-doped SiO 2 nanoparticles could be changed by varying the molar ratio of water to surfactant. The sizes and the morphologies of the erbium-doped SiO 2 nanoparticles were examined by using a transmission electron microscope. The average size of synthesized erbium-doped SiO 2 nanoparticles was approximately 20 - 25 nm and that of the erbium particles was 3 - 5 nm. The effects of the synthesis parameters, such as the molar ratio of water to surfactant, are discussed.

  4. Structure and reactivity in reverse micelles

    International Nuclear Information System (INIS)

    Pileni, M.P.

    1989-01-01

    This book gives an up-to-date, comprehensive assessment of current knowledge in the very fast-moving field of reverse micelles, ranging from physical studies to biotechnological applications. Starting with physical and spectroscopic studies of reverse micelle structure at the macro- and microstructural levels, topics dealt with in detail are the NMR spectroscopy of reverse micells, fluorescence quenching kinetics, photochemical behaviour, role and behaviour of hydrated electrons in reverse micelles, including femtosecond phenomena, reactivity-dependent applications such as microlatex formation, protein partitioning, extraction, and purification. The microreactor characteristics of reverse micelles are shown to allow formation of semiconductor clusters, peptide synthesis through enzyme-catalyzed reactions, reaction product extraction, and enhanced-reactivity phenomena. The reactivity effects and their consequences are particularly highlighted throughout the book

  5. DNA-based machines.

    Science.gov (United States)

    Wang, Fuan; Willner, Bilha; Willner, Itamar

    2014-01-01

    The base sequence in nucleic acids encodes substantial structural and functional information into the biopolymer. This encoded information provides the basis for the tailoring and assembly of DNA machines. A DNA machine is defined as a molecular device that exhibits the following fundamental features. (1) It performs a fuel-driven mechanical process that mimics macroscopic machines. (2) The mechanical process requires an energy input, "fuel." (3) The mechanical operation is accompanied by an energy consumption process that leads to "waste products." (4) The cyclic operation of the DNA devices, involves the use of "fuel" and "anti-fuel" ingredients. A variety of DNA-based machines are described, including the construction of "tweezers," "walkers," "robots," "cranes," "transporters," "springs," "gears," and interlocked cyclic DNA structures acting as reconfigurable catenanes, rotaxanes, and rotors. Different "fuels", such as nucleic acid strands, pH (H⁺/OH⁻), metal ions, and light, are used to trigger the mechanical functions of the DNA devices. The operation of the devices in solution and on surfaces is described, and a variety of optical, electrical, and photoelectrochemical methods to follow the operations of the DNA machines are presented. We further address the possible applications of DNA machines and the future perspectives of molecular DNA devices. These include the application of DNA machines as functional structures for the construction of logic gates and computing, for the programmed organization of metallic nanoparticle structures and the control of plasmonic properties, and for controlling chemical transformations by DNA machines. We further discuss the future applications of DNA machines for intracellular sensing, controlling intracellular metabolic pathways, and the use of the functional nanostructures for drug delivery and medical applications.

  6. Reverse micelles directed synthesis of TiO{sub 2}-CeO{sub 2} mixed oxides and investigation of their crystal structure and morphology

    Energy Technology Data Exchange (ETDEWEB)

    Matejova, Lenka, E-mail: matejova@icpf.cas.cz [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Department of Catalysis and Reaction Engineering, Rozvojova 135, 165 02 Prague 6 (Czech Republic); Vales, Vaclav [Charles University in Prague, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Fajgar, Radek [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Department of Aerosols and Laser Studies, Rozvojova 135, 165 02 Prague 6 (Czech Republic); Matej, Zdenek; Holy, Vaclav [Charles University in Prague, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Solcova, Olga [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Department of Catalysis and Reaction Engineering, Rozvojova 135, 165 02 Prague 6 (Czech Republic)

    2013-02-15

    The synthesis of TiO{sub 2}-CeO{sub 2} mixed oxides based on the sol-gel process controlled within reverse micelles of non-ionic surfactant Triton X-114 in cyclohexane is reported. The crystallization, phase composition, trends in nanoparticles growth and porous structure properties are studied as a function of Ti:Ce molar composition and annealing temperature by in-situ X-ray diffraction, Raman spectroscopy and physisorption. The brannerite-type CeTi{sub 2}O{sub 6} crystallizes as a single crystalline phase at Ti:Ce molar composition of 70:30 and in the mixture with cubic CeO{sub 2} and anatase TiO{sub 2} for composition 50:50. At Ti:Ce molar ratios 90:10 and 30:70 the mixtures of TiO{sub 2} anatase, rutile and cubic CeO{sub 2} appear. In these mixtures TiO{sub 2} rutile is formed at higher temperatures than conventionally. Additionally, the amount of a present amorphous phase in individual mixtures was estimated from diffraction data. The porous structure morphology depends both on molar composition and annealing temperature. This is correlated with the presence of carbon impurities of different character. - Graphical abstract: The phase composition of Ti90--Ce10 and Ti50--Ce50 oxide mixtures as a function of annealing temperature. The amount of the amorphous phase was estimated and attributed to TiO{sub 2}. Highlights: Black-Right-Pointing-Pointer Ti/Ce oxides were prepared using reverse micelles of Triton X-114. Black-Right-Pointing-Pointer Crystallization of TiO{sub 2}, CeO{sub 2} or CeTi{sub 2}O{sub 6} depends on Ti:Ce molar ratio. Black-Right-Pointing-Pointer Amorphous phase attributed to TiO{sub 2} was identified. Black-Right-Pointing-Pointer Metal oxides surface area is influenced by the character of present carbon impurities.

  7. Musk Oxen and Micelles

    Science.gov (United States)

    Hill, John W.

    1996-09-01

    Musk oxen behavior provides an analogy to micelle formation by amphipathic substances. Mature male musk oxen protect their young and females from wolves by forming a protective circle around them. The males stand with their tails to the inside and their heads facing outward. Amphipathic substances such as soap form micelles. The hydrophobic hydrocarbon tails of the soap are turned to the inside of the micelle and the hydrophilic carboxylate heads are on the outside at the interface with the polar water molecules.

  8. Synthesis and in vitro experiments of carcinoma vascular endothelial targeting polymeric nano-micelles combining small particle size and supermagnetic sensitivity.

    Science.gov (United States)

    Zhang, Yi; Pan, Jielin; Xu, Qilan; Li, Hao; Wang, Jianhao; Zhang, Chao; Hong, Guobin

    2018-01-01

    Objective: To construct carcinoma vascular endothelial-targeted polymeric nanomicelles with high magnetic resonance imaging (MRI) sensitivity and to evaluate their biological safety and in vitro tumor-targeting effect, and to monitor their feasibility using clinical MRI scanner. Method: Amphiphilic block copolymer, poly(ethylene glycol)- b -poly(ε-caprolactone) (PEG-PCL) was synthesized via the ring-opening polymerization of ε-caprolactone (CL) initiated by poly(ethylene glycol) (PEG), in which cyclic pentapeptide Arg-Gly-Asp (cRGD) was conjugated with the terminal of hydrophilic PEG block. During the self-assembly of PEG-PCL micelles, superparamagnetic γ-Fe 2 O 3 nanoparticles (11 nm) was loaded into the hydrophobic core. The cRGD-terminated γ-Fe 2 O 3 -loaded polymeric micelles targeting to carcinoma vascular endothelial cells, were characterized in particle size, morphology, loading efficiency and so on, especially high MRI sensitivity in vitro. Normal hepatic vascular endothelial cells (ED25) were incubated with the resulting micelles for assessing their safety. Human hepatic carcinoma vascular endothelial cells (T3A) were cultured with the resulting micelles to assess the micelle uptake using Prussian blue staining and the cell signal intensity using MRI. Results: All the polymeric micelles exhibited ultra-small particle sizes with approximately 50 nm, high relaxation rate, and low toxicity even at high iron concentrations. More blue-stained iron particles were present in the targeting group than the non-targeting and competitive inhibition groups. In vitro MRI showed T 2 WI and T 2 relaxation times were significantly lower in the targeting group than in the other two groups. Conclusion: γ-Fe 2 O 3 -loaded PEG-PCL micelles not only possess ultra-small size and high superparamagnetic sensitivity, also can be actively targeted to carcinoma vascular endothelial cells by tumor-targeted cRGD. It appears to be a promising contrast agent for tumor

  9. DNA-based asymmetric catalysis

    NARCIS (Netherlands)

    Boersma, Arnold J.; Megens, Rik P.; Feringa, Ben L.; Roelfes, Gerard

    2010-01-01

    The unique chiral structure of DNA has been a source of inspiration for the development of a new class of bio-inspired catalysts. The novel concept of DNA-based asymmetric catalysis, which was introduced only five years ago, has been applied successfully in a variety of catalytic enantioselective

  10. 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

  11. Synthesis and Characterization of Micelle-Forming PEG-Poly(Amino Acid) Copolymers with Iron-Hydroxamate Cross-Linkable Blocks for Encapsulation and Release of Hydrophobic Drugs.

    Science.gov (United States)

    Sill, Kevin N; Sullivan, Bradford; Carie, Adam; Semple, J Edward

    2017-06-12

    Described is the development of a polymeric micelle drug delivery platform that addresses the physical property limitations of many nanovectors. The system employs triblock copolymers comprised of a hydrophilic poly(ethylene glycol) (PEG) block, and two poly(amino acid) (PAA) blocks: a stabilizing cross-linking central block, and a hydrophobic drug encapsulation block. Detailed description of synthetic strategies and considerations found to be critical are discussed. Of note, it was determined that the purity of the α-amino acid-N-carboxyanhydrides (NCA) monomers and PEG macroinitiator are ultimately responsible for impurities that arise during the polymerization. Also, contrary to current beliefs in the field, the presence of water does not adversely affect the polymerization of NCAs. Furthermore, we describe the impact of poly(amino acid) conformational changes, through the incorporation of d-amino acids to form mixed stereochemistry PAA blocks, with regard to the physical and pharmacokinetic properties of the resulting micelles.

  12. Reverse Micelles Directed Synthesis of TiO2-CeO2 Mixed Oxides and Investigation of Their Crystal Structure and Morphology

    Czech Academy of Sciences Publication Activity Database

    Matějová, Lenka; Valeš, V.; Fajgar, Radek; Matěj, Z.; Holý, V.; Šolcová, Olga

    2013-01-01

    Roč. 198, FEB (2013), s. 485-495 ISSN 0022-4596 R&D Projects: GA ČR GA203/09/1117; GA TA ČR TA01020804 Grant - others:GA ČR(CZ) GAP204/11/0785 Institutional support: RVO:67985858 Keywords : titania–ceria * cerium titanate * sol-gel preparation * reverse micelle * X-ray diffraction * Raman spectroscopy Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.200, year: 2013

  13. 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.

  14. Stepwise Thermo-Responsive Amino Acid-Derived Triblock Vinyl Polymers: ATRP Synthesis of Polymers, Aggregation, and Gelation Properties via Flower-Like Micelle Formation

    Directory of Open Access Journals (Sweden)

    Nobuyuki Higashi

    2018-03-01

    Full Text Available Novel thermo-responsive ABA-type triblock copolymers (poly(NAAMen-b-NAGMe240-b-NAAMen, n = 18–72 composed of naturally occurring amino acid–based vinyl polymer blocks such as poly(N-acryloyl-l-alanine methyl ester (poly(NAAMe as the A segment and poly(N-acryloyl-glycine methylester(poly(NAGMe as the B segment have been synthesized by the atom transfer radical polymerization (ATRP. Their thermal behaviors were analyzed in dilute aqueous solutions by turbidimetry. The turbidity curves provided two-step LCST transitions, and a flower-like micelle formation was confirmed at the temperature region between the first and second LCST transitions by dynamic light scattering, AFM and TEM. At higher copolymer concentrations, hydrogels were obtained at temperatures above the first LCST due to network formation induced with the flower-like micelles as cross-linker. The hydrogels were found to be switched to a sol state when cooled below the first LCST. These hydrogels also exhibited self-healable and injectable capabilities, which were evaluated by rheological measurements.

  15. DNA based radiological dosimetry technology

    International Nuclear Information System (INIS)

    Diaz Quijada, Gerardo A.; Roy, Emmanuel; Veres, Teodor; Dumoulin, Michel M.; Vachon, Caroline; Blagoeva, Rosita; Pierre, Martin

    2008-01-01

    Full text: The purpose of this project is to develop a personal and wearable dosimeter using a highly-innovative approach based on the specific recognition of DNA damage with a polymer hybrid. Our biosensor will be sensitive to breaks in nucleic acid macromolecules and relevant to mixed-field radiation. The dosimeter proposed will be small, field deployable and will sense damages for all radiation types at the DNA level. The generalized concept for the novel-based radiological dosimeter: 1) Single or double stranded oligonucleotide is immobilized on surface; 2) Single stranded has higher cross-section for fragmentation; 3) Double stranded is more biological relevant; 4) Radiation induces fragmentation; 5) Ultra-sensitive detection of fragments provides radiation dose. Successful efforts have been made towards a proof-of-concept personal wearable DNA-based dosimeter that is appropriate for mixed-field radiation. The covalent immobilization of oligonucleotides on large areas of plastic surfaces has been demonstrated and corroborated spectroscopically. The surface concentration of DNA was determined to be 8 x 1010 molecules/cm 2 from a Ce(IV) catalyzed hydrolysis study of a fluorescently labelled oligonucleotide. Current efforts are being directed at studying radiation induced fragmentation of DNA followed by its ultra-sensitive detection via a novel method. In addition, proof-of-concept wearable personal devices and a detection platform are presently being fabricated. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-12-01

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

  17. Synthesis and characterization of aspartic acid-capped CdS/ZnS quantum dots in reverse micelles and its application to Hg(II) determination

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Mohammad Saeid, E-mail: mshosseini1336@yahoo.com; Kamali, Mohsen

    2015-11-15

    In this work, CdS/ZnS quantum dots (QDs) coated with aspartic acid (AsA) were synthesized in reverse micelles. The synthesized QDs were characterized by XRD, TEM, IR and photoluminescence (PL) spectroscopy. It was found that the intensity of CdS/ZnS QDs coated with AsA is much greater than CdS, and CdS/ZnS QDs. The interaction of some heavy metal ions with CdS/ZnS/AsA QDs was investigated at different buffering pH media. Based on the PL quenching of the QDs in the presence of each one of the metal ions, the feasibility of their determinations was examined according to the Stern–Volmer equation. The investigations showed that Hg(II) ions can be easily determined in contaminated atmospheric environments with the detection limit of 0.05 mg m{sup −3}. The results were satisfactorily confirmed by cold vapor atomic absorption spectrometric method. - Highlights: • A new CdS/ZnS quantum dot capped with aspartic acid (DDBA) was prepared. • The prepared QDs benefit from a favorable fluorescence. • Interaction of some metal ions with the QDs was examined according to the Stern–Volmer equation. • The determination of Hg(II) is feasible in the present of many co-existence metal ions. • The method benefits from a high-speed and considerable simplicity for Hg(II) determination.

  18. Synthesis of visible light driven cobalt tailored Ag2O/TiON nanophotocatalyst by reverse micelle processing for degradation of Eriochrome Black T

    KAUST Repository

    Hussain, Syed Tajammul

    2013-02-01

    An ultra efficient cobalt tailored silver and nitrogen co-doped titania (TiON/Ag2O/Co) visible nanophotocatalyst is successfully synthesized using modified reverse micelle processing. Composition, phase, distribution of dopants, functional group analysis, optical properties and morphology of synthesized materials are investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) based techniques and others. Charge states of titanium (Ti) and silver are explored through core-loss electron energy loss spectroscopy (EELS) analysis and X ray photoelectron spectroscopy (XPS). Our characterization results showed that the synthesized nanophotocatalyst consisted of anatase phased qausispherical nanoparticles that exhibited homogeneous distribution of dopants, large surface area, high quantum efficiency and enhanced optical properties. At lower content of doped Co ions, the TiON/Ag2O responded with extraordinary photocatalytic properties. The cobalt tailored nanophotocatalyst showed remarkable activity against Eriochrome Black T (EBT). Moreover, comparative degradation behavior of EBT with TiON, Ag2O/TiON and Co/Ag2O/TiON is also investigated. © 2012 Elsevier Ltd.

  19. Synthesis of TiO{sub 2} nanoparticles by self-assembling reverse micelle cores of PS-b-PAA for functional textile applications

    Energy Technology Data Exchange (ETDEWEB)

    Akpolat, Leyla Budama; Çakır, Burçin Acar; Topel, Önder, E-mail: ondertopel@akdeniz.edu.tr; Hoda, Numan, E-mail: nhoda@akdeniz.edu.tr

    2015-04-15

    Highlights: • TiO{sub 2} nanoparticles were synthesized within poly(styrene)-b-poly(acrylic acid) micelles. • The copolymer solution including nano TiO{sub 2} was coated onto textile fabrics. • UV-protective factor of nano TiO{sub 2} coated fabrics was estimated as 50+. • Nano TiO{sub 2} coated fabrics was found to exhibit a high photocatalytic activity. - Abstract: Titanium dioxide (i.e., titanium(IV) oxide, TiO{sub 2}) nanoparticles have been fabricated using a copolymer templating technique in micellar solution of poly(styrene)-block-poly(acrylic acid), PS(10912)-b-PAA(4842) synthesized by atom transfer radical polymerization (ATRP). The size and morphology of the synthesized TiO{sub 2} nanoparticles have been characterized via TEM and XRD measurements. The average size of TiO{sub 2} nanoparticles was determined as 13 ± 3 and 13 ± 4 nm for titanium:copolymer ratios of 20:1 and 33:1, respectively. The copolymer solution including nano TiO{sub 2} particles has been coated onto textile fabrics to enhance their UV-blocking and self-cleaning properties. It has been determined that nano TiO{sub 2} coated textile fabrics have very good UV-blocking properties with 50+ of the ultraviolet protecting factor (UPF) and high photocatalytic efficiency with 69.2% of the photodegradation of methylene blue.

  20. 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

  1. On the anomalies in gold nanoparticles prepared by micelle nanolithography and their impact on one-dimensional material synthesis. Role of substrate, size effects and impurity

    Energy Technology Data Exchange (ETDEWEB)

    Mbenkum, B.N.

    2007-07-23

    The synthesis of one-dimensional (1-D) inorganic semiconductor materials such as nanotubes and silicon (Si) nanowires is usually achieved by catalyst nanoparticlemediated synthetic routes. Despite the well-established nature of this technique, problems such as low temperature synthesis and adequate control of catalyst nanoparticle diameter in order to control 1-D material diameter still prevail. Additionally, the expansion of this technology from crystalline to cheaper substrates such as glass remains demanding. This work employs a previously established selfassembly route to produce controlled spatial distribution of substrate anchored small diameter gold nanoparticles with controlled size. This enabled successful synthesis of Si 1-D structures with controlled diameters less than 20 nm. Low temperature synthesis due to enhanced catalytic activity was achieved via introduction of impurity by treatment of gold nanoparticles in different plasma environments. This enabled Si 1-D structure growth on Si, SiO{sub x}/Si and borosilicate glass substrates at 320 C. Substrate-induced stress affected Si diffusion at the gold nanoparticle determining whether Si nanowires or nanotubes were grown. These results are of technological relevance because low temperature synthesis provides an economical approach and controlled diameter enhances material functionality. Additionally, exploiting substrate-induced stress to influence Si diffusion in nanoparticles provides an alternate route to tuning Si 1-D structure. (orig.)

  2. Micelle-Directing Synthesis of Ag-Doped WO3and MoO3Composites for Photocatalytic Water Oxidation and Organic-Dye Adsorption.

    Science.gov (United States)

    Bate, Nasen; Shi, Hongfei; Chen, Li; Wang, Jiabo; Xu, Shasha; Chen, Weilin; Li, Jianping; Wang, Enbo

    2017-10-05

    In this paper, an Ag-doped WO 3 (and MoO 3 ) composite has been prepared by following a simple micelle-directed method and high-temperature sintering route. The as-prepared samples were characterized by X-ray diffraction, inductively coupled plasma, transmission electron microscopy, X-ray photoelectron spectroscopy, UV/Vis diffuse reflectance spectroscopy, Brunauer-Emmett-Teller, photoluminescence spectroscopy, and electrochemical impedance spectroscopy techniques. The photocatalytic experiments reveal that their oxygen-production rates are up to 95.43 μmol (75.45 μmol) for Ag-doped WO 3 (MoO 3 ), which is 9.5 (7.3) times higher than that of pure WO 3 : 9.012 μmol (MoO 3 : 9.00 μmol) under visible-light illumination (λ≥420 nm), respectively. The improvement of their photocatalytic activity is attributed to the enhancement of their visible-light absorption and the separation efficiency of photogenerated carriers by Ag doping. Moreover, Ag-doped WO 3 (MoO 3 ) also shows excellent adsorption of rhodamine B (RhB) and methylene blue (MB) in aqueous solution, with maximum adsorption capacities towards RhB and MB of 822 and 820 mg g -1 for Ag-doped WO 3 , and 642 and 805 mg g -1 for Ag-doped MoO 3 , respectively. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. DNA-based random number generation in security circuitry.

    Science.gov (United States)

    Gearheart, Christy M; Arazi, Benjamin; Rouchka, Eric C

    2010-06-01

    DNA-based circuit design is an area of research in which traditional silicon-based technologies are replaced by naturally occurring phenomena taken from biochemistry and molecular biology. This research focuses on further developing DNA-based methodologies to mimic digital data manipulation. While exhibiting fundamental principles, this work was done in conjunction with the vision that DNA-based circuitry, when the technology matures, will form the basis for a tamper-proof security module, revolutionizing the meaning and concept of tamper-proofing and possibly preventing it altogether based on accurate scientific observations. A paramount part of such a solution would be self-generation of random numbers. A novel prototype schema employs solid phase synthesis of oligonucleotides for random construction of DNA sequences; temporary storage and retrieval is achieved through plasmid vectors. A discussion of how to evaluate sequence randomness is included, as well as how these techniques are applied to a simulation of the random number generation circuitry. Simulation results show generated sequences successfully pass three selected NIST random number generation tests specified for security applications.

  4. 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.

  5. 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.

  6. 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.

  7. Folated Synperonic-Cholesteryl Hemisuccinate Polymeric Micelles for the Targeted Delivery of Docetaxel in Melanoma

    Directory of Open Access Journals (Sweden)

    Jaleh Varshosaz

    2015-01-01

    Full Text Available The objective of this study was the synthesis of folic acid- (FA- targeted polymeric micelles of Synperonic PE/F 127-cholesteryl hemisuccinate (PF127-Chol for specific delivery of docetaxel (DTX. Targeted or nontargeted micelles loaded with DTX were prepared via dialysis method. The effects of processing variables on the physicochemical properties of targeted micelles were evaluated using a full factorial design. After the optimization of the polymer/drug ratio, the organic solvent type used for the preparation of the micelles, and the temperature of dialyzing medium, the in vitro cytotoxicity and cellular uptake of the optimized micelles were studied on B16F10 melanoma cells by flow cytometry and fluorescent microscopy. The anticancer efficacy of DTX-loaded FA-PF127-Chol was evaluated in mice bearing melanoma tumor. Optimized targeted micelles had the particle size of 171.3 nm, zeta potential of −7.8 mV, PDI of 0.325, and a high encapsulation efficiency that released the drug within 144 h. The MTT assay indicated that targeted micelles carrying DTX were significantly more cytotoxic, had higher cellular uptake, and reduced the tumor volume significantly more than the nontargeted micelles and the free drug. FA-PF127-Chol could be, therefore, a promising biomaterial for tumors overexpressing folate receptors.

  8. Synthesis, characterisation, and in vitro cellular uptake kinetics of nanoprecipitated poly(2-methacryloyloxyethyl phosphorylcholine-b-poly(2-(diisopropylaminoethyl methacrylate (MPC-DPA polymeric nanoparticle micelles for nanomedicine applications

    Directory of Open Access Journals (Sweden)

    Jonathan P. Salvage

    2016-01-01

    Full Text Available Abstract Nanoscience offers the potential for great advances in medical technology and therapies in the form of nanomedicine. As such, developing controllable, predictable, and effective, nanoparticle-based therapeutic systems remains a significant challenge. Many polymer-based nanoparticle systems have been reported to date, but few harness materials with accepted biocompatibility. Phosphorylcholine (PC based biomimetic materials have a long history of successful translation into effective commercial medical technologies. This study investigated the synthesis, characterisation, nanoprecipitation, and in vitro cellular uptake kinetics of PC-based polymeric nanoparticle micelles (PNM formed by the biocompatible and pH responsive block copolymer poly(2-methacryloyloxyethyl phosphorylcholine-b-poly(2-(diisopropylaminoethyl methacrylate (MPC-DPA. Atom transfer radical polymerisation (ATRP, and gel permeation chromatography (GPC were used to synthesise and characterise the well-defined MPC100-DPA100 polymer, revealing organic GPC, using evaporative light scatter detection, to be more accurate than aqueous GPC for this application. Subsequent nanoprecipitation investigations utilising photon correlation spectroscopy (PCS revealed PNM size increased with polymer concentration, and conferred Cryo-stability. PNM diameters ranged from circa 64–69 nm, and increased upon hydrophobic compound loading, circa 65–71 nm, with loading efficiencies of circa 60 % achieved, whilst remaining monodisperse. In vitro studies demonstrated that the PNM were of low cellular toxicity, with colony formation and MTT assays, utilising V79 and 3T3 cells, yielding comparable results. Investigation of the in vitro cellular uptake kinetics revealed rapid, 1 h, cellular uptake of MPC100-DPA100 PNM delivered fluorescent probes, with fluorescence persistence for 48 h. This paper presents the first report of these novel findings, which highlight the potential of the system

  9. Random amplified polymorphic DNA based genetic characterization ...

    African Journals Online (AJOL)

    Random amplified polymorphic DNA based genetic characterization of four important species of Bamboo, found in Raigad district, Maharashtra State, India. ... Bambusoideae are differentiated from other members of the family by the presence of petiolate blades with parallel venation and stamens are three, four, six or more, ...

  10. Portable and Error-Free DNA-Based Data Storage.

    Science.gov (United States)

    Yazdi, S M Hossein Tabatabaei; Gabrys, Ryan; Milenkovic, Olgica

    2017-07-10

    DNA-based data storage is an emerging nonvolatile memory technology of potentially unprecedented density, durability, and replication efficiency. The basic system implementation steps include synthesizing DNA strings that contain user information and subsequently retrieving them via high-throughput sequencing technologies. Existing architectures enable reading and writing but do not offer random-access and error-free data recovery from low-cost, portable devices, which is crucial for making the storage technology competitive with classical recorders. Here we show for the first time that a portable, random-access platform may be implemented in practice using nanopore sequencers. The novelty of our approach is to design an integrated processing pipeline that encodes data to avoid costly synthesis and sequencing errors, enables random access through addressing, and leverages efficient portable sequencing via new iterative alignment and deletion error-correcting codes. Our work represents the only known random access DNA-based data storage system that uses error-prone nanopore sequencers, while still producing error-free readouts with the highest reported information rate/density. As such, it represents a crucial step towards practical employment of DNA molecules as storage media.

  11. DNA-Based Applications in Nanobiotechnology

    Directory of Open Access Journals (Sweden)

    Khalid M. Abu-Salah

    2010-01-01

    Full Text Available Biological molecules such as deoxyribonucleic acid (DNA have shown great potential in fabrication and construction of nanostructures and devices. The very properties that make DNA so effective as genetic material also make it a very suitable molecule for programmed self-assembly. The use of DNA to assemble metals or semiconducting particles has been extended to construct metallic nanowires and functionalized nanotubes. This paper highlights some important aspects of conjugating the unique physical properties of dots or wires with the remarkable recognition capabilities of DNA which could lead to miniaturizing biological electronics and optical devices, including biosensors and probes. Attempts to use DNA-based nanocarriers for gene delivery are discussed. In addition, the ecological advantages and risks of nanotechnology including DNA-based nanobiotechnology are evaluated.

  12. Glyco-Nanoparticles Made from Self-Assembly of Maltoheptaose-block-Poly(methyl methacrylate): Micelle, Reverse Micelle, and Encapsulation.

    Science.gov (United States)

    Zepon, Karine M; Otsuka, Issei; Bouilhac, Cécile; Muniz, Edvani C; Soldi, Valdir; Borsali, Redouane

    2015-07-13

    The synthesis and the solution-state self-assembly of the "hybrid" diblock copolymers, maltoheptaose-block-poly(methyl methacrylate) (MH-b-PMMA), into large compound micelles (LCMs) and reverve micelle-type nanoparticles, are reported in this paper. The copolymers were self-assembled in water and acetone by direct dissolution method, and the morphologies of the nanoparticles were investigated by dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), atomic force microscopy (AFM), proton nuclear magnetic resonance ((1)H NMR), and fluorescence spectroscopy as a function of the volume fraction of the copolymer hydrophobic block, copolymer concentration, stirring speed, and solvent polarity. The DLS measurements and TEM images showed that the hydrodynamic radius (Rh) of the LCMs obtained in water increases with the copolymer concentration. Apart from that, increasing the stirring speed leads to polydispersed aggregations of the LCMs. On the other hand, in acetone, the copolymers self-assembled into reverse micelle-type nanoparticles having Rh values of about 6 nm and micellar aggregates, as revealed the results obtained from DLS, AFM, and (1)H NMR analyses. The variation in micellar structure, that is, conformational inversion from LCMs to reverse micelle-type structures in response to polarity of the solvent, was investigated by apparent water contact angle (WCA) and (1)H NMR analyses. This conformational inversion of the nanoparticles was further confirmed by encapsulation and release of hydrophobic guest molecule, Nile red, characterized by fluorescence spectroscopy.

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

    DEFF Research Database (Denmark)

    Ek, Pramod Kumar

    or comicellisation strategy. In this approach, the amphiphilic triblock copolymers synthesized by ATRP were further modified, and conjugated with targeting ligands and fluorophores. The co-micellisation of this functionalized amphiphilic triblock copolymers resulted in functionalized mixed micelle nanosensors. Post......-shellcorona micelle based ratiometric fluorescence pH nanosensor fabrications. Two synthetic strategies such as post micelle modification and mixed micellisation (co-micellisation) were employed for pH nanosensor synthesis. In the post micelle modification strategy, dimensional synthetic modifications on polymer...... synthesized with sensitivity ranges that were appropriate for pH measurements in living cells. The sensitivity ranges of the nanosensors were simply altered by changing the fluorophores conjugated to the shell region. Nanosensors having targeting capabilities were synthesized by mixed micellisation...

  14. Polymeric micelles for drug targeting.

    Science.gov (United States)

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

    2007-11-01

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

  15. Novel Amphiphilic, Biodegradable, Biocompatible, Thermo-Responsive ABA Triblock Copolymers Based on PCL and PEG Analogues via a Combination of ROP and RAFT: Synthesis, Characterization, and Sustained Drug Release from Self-Assembled Micelles

    Directory of Open Access Journals (Sweden)

    Wenyan Ning

    2018-02-01

    Full Text Available Well-defined novel, linear, biodegradable, amphiphilic thermo-responsive ABA-type triblock copolymers, poly[2-(2-methoxyethoxy ethyl methacrylate-co-oligo(ethylene glycol methacrylate]-b-poly(ε-caprolactone-b-poly[2-(2-methoxyethoxy ethyl methacrylate-co-oligo(ethylene glycol methacrylate] [P(MEO2MA-co-OEGMA-b-PCL-b-P(MEO2MA-co-OEGMA] (tBPs, were synthesized via a combination of ring-opening polymerization (ROP of ε-caprolactone (εCL and reversible addition-fragmentation chain transfer polymerization (RAFT of MEO2MA and OEGMA comonomers. The chemical structures and compositions of these copolymers were characterized using Fourier transform infrared spectroscopy (FT-IR and proton nuclear magnetic resonance (1H NMR. The molecular weights of the copolymers were obtained using gel permeation chromatography (GPC measurements. Thermo-responsive micelles were obtained by self-assembly of copolymers in aqueous medium. The temperature sensitivity and micelllization behavior of amphiphilic triblock copolymers solutions were studied by transmittance, fluorescence probe, surface tension, dynamic light scattering (DLS and transmission electron microscopy (TEM. A hydrophobic drug, anethole, was encapsulated in micelles by using the dialysis method. The average particle sizes of drug-loaded micelles were determined by dynamic light scattering measurement. In vitro, the sustained release of the anethole was performed in pH 7.4 phosphate-buffered saline (PBS at different temperatures. Results showed that the triblock copolymer’s micelles were quite effective in the encapsulation and controlled release of anethole. The vial inversion test demonstrated that the triblock copolymers could trigger the sol-gel transition which also depended on the temperature, and its sol-gel transition temperature gradually decreased with increasing concentration. The hydrogel system could also be used as a carrier of hydrophobic drugs in medicine.

  16. Excited state dynamics of DNA bases

    Czech Academy of Sciences Publication Activity Database

    Kleinermanns, K.; Nachtigallová, Dana; de Vries, M. S.

    2013-01-01

    Roč. 32, č. 2 (2013), s. 308-342 ISSN 0144-235X R&D Projects: GA ČR GAP208/12/1318 Grant - others:National Science Foundation(US) CHE-0911564; NASA(US) NNX12AG77G; Deutsche Forschungsgemeinschaft(DE) SFB 663; Deutsche Forschungsgemeinschaft(DE) KI 531-29 Institutional support: RVO:61388963 Keywords : DNA bases * nucleobases * excited state * dynamics * computations * gas phase * conical intersections Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.920, year: 2013

  17. Thermally sensitive dual fluorescent polymeric micelles for probing cell properties

    NARCIS (Netherlands)

    Li Feng, F.; Westphal, A.H.; Marcelis, A.T.M.; Sudhölter, E.J.R.; Cohen Stuart, M.A.; Leermakers, F.A.M.

    2011-01-01

    Dual fluorescent micelles with a hydrophobic probe (HMA) embedded in the micelle core and a hydrophilic probe (TRITC) attached on the micelle corona were prepared. These micelles can act as nanometre-sized thermal sensors. Within a short temperature range, the fluorescent emission of the micelles

  18. Ultrafast dynamics of solvation and charge transfer in a DNA-based biomaterial.

    Science.gov (United States)

    Choudhury, Susobhan; Batabyal, Subrata; Mondol, Tanumoy; Sao, Dilip; Lemmens, Peter; Pal, Samir Kumar

    2014-05-01

    Charge migration along DNA molecules is a key factor for DNA-based devices in optoelectronics and biotechnology. The association of a significant amount of water molecules in DNA-based materials for the intactness of the DNA structure and their dynamic role in the charge-transfer (CT) dynamics is less documented in contemporary literature. In the present study, we have used a genomic DNA-cetyltrimethyl ammonium chloride (CTMA) complex, a technological important biomaterial, and Hoechest 33258 (H258), a well-known DNA minor groove binder, as fluorogenic probe for the dynamic solvation studies. The CT dynamics of CdSe/ZnS quantum dots (QDs; 5.2 nm) embedded in the as-prepared and swollen biomaterial have also been studied and correlated with that of the timescale of solvation. We have extended our studies on the temperature-dependent CT dynamics of QDs in a nanoenvironment of an anionic, sodium bis(2-ethylhexyl)sulfosuccinate reverse micelle (AOT RMs), whereby the number of water molecules and their dynamics can be tuned in a controlled manner. A direct correlation of the dynamics of solvation and that of the CT in the nanoenvironments clearly suggests that the hydration barrier within the Arrhenius framework essentially dictates the charge-transfer dynamics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Controlling lipid micelle stability using oligonucleotide headgroups.

    Science.gov (United States)

    Wilner, Samantha E; Sparks, Samuel E; Cowburn, David; Girvin, Mark E; Levy, Matthew

    2015-02-18

    Lipid-based micelles provide an attractive option for therapeutic and diagnostic applications because of their small size (24 h. Using antisense oligonucleotides we demonstrated that disruption of the quadruplex leads to micelle destabilization and cargo release. The ability to use oligonucleotide interactions to control lipid particle stability represents a new approach in the design of programmed nanoscale devices.

  20. Vibrational dynamics of ice in reverse micelles

    NARCIS (Netherlands)

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

    2008-01-01

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

  1. 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......-linked by an amidation reaction using 3,6,9-trioxaundecandioic acid cross-linker. The cross-linked micelle was functionalized with two pH sensitive fluorophores and one reference fluorophore, which resulted in a highly uniform ratiometric pH nanosensor with a diameter of 29 nm. The use of two sensor fluorophores...... 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....

  2. 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.

  3. 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.

  4. Polymeric Micelles for Acyclovir Drug Delivery

    OpenAIRE

    Sawdon, Alicia J.; Peng, Ching-An

    2014-01-01

    Polymeric prodrug micelles for delivery of acyclovir (ACV) were synthesized. First, ACV was used directly to initiate ring-opening polymerization of ε-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. 1H NMR, FTIR, and gel permeation chromatography were employed to show successful conjugation of MPEG or chitosan to hydrophobic ACV-P...

  5. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Micelles As Delivery System for Cancer Treatment.

    Science.gov (United States)

    Keskin, Dilek; Tezcaner, Aysen

    2017-01-01

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

  7. Natural DNA-Based Nonvolatile Resistive Switching Memory (Preprint)

    Science.gov (United States)

    2017-12-06

    AFRL-RX-WP-JA-2017-0510 NATURAL DNA-BASED NONVOLATILE RESISTIVE SWITCHING MEMORY (PREPRINT) Huei-Yau Jeng, Tzu-Chien Yang , Li...2017 Interim 24 January 2014 – 6 November 2017 4. TITLE AND SUBTITLE NATURAL DNA-BASED NONVOLATILE RESISTIVE SWITCHING MEMORY (PREPRINT) 5a...study, we present a resistive switching memory device based on natural DNA biomaterial. The structure consists of a DNA layer sandwiched by two

  8. Synthesis of star-branched PLA-b-PMPC copolymer micelles as long blood circulation vectors to enhance tumor-targeted delivery of hydrophobic drugs in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Long, Li-xia [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin 300072 (China); Zhao, Jin, E-mail: zhaojin@tju.edu.cn [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin 300072 (China); Li, Ke; He, Li-gang; Qian, Xiao-ming; Liu, Chao-yong; Wang, Li-mei; Yang, Xin-qi [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin 300072 (China); Sun, Jinjin [Department of General Surgery, The Second Hospital of Tianjin Medical University, Tianjin 300211 (China); Ren, Yu [Tianjin Research Center of Basic Medical Science, Tianjin Medical University, Tianjin 300070 (China); Kang, Chun-sheng, E-mail: kang97061@yahoo.com [Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin 300052 (China); Yuan, Xu-bo, E-mail: xbyuan@tju.edu.cn [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin 300072 (China)

    2016-09-01

    Star-branched amphiphilic copolymer nanocarriers with high-density zwitterionic shell show great promise in drug delivery due to their controllable small size and excellent anti-biofouling properties. This gives the hydrophobic cargo with high stability and long blood circulation in vivo. In the present study, star-branched polylactic acid and poly(2-methacryloyloxyethyl phosphorylcholine) copolymers with (AB{sub 3}){sub 3}–type architecture (PLA-b-PMPC{sub 3}){sub 3} were conceived as drug vectors, and the copolymers were synthesized by an “arm-first” approach via the combination of ring opening polymerization (ROP), atom transfer radical polymerization (ATRP) and the click reaction. The self-assembled star-branched copolymer micelles (sCPM) had an average diameter of about 64.5 nm and exhibited an ultra-hydrophilic surface with an ultralow water contact angle of about 12.7°, which efficiently suppressed the adhesion of serum proteins. In vivo experiments showed that the sCPM loading strongly enhanced the blood circulation time of DiI and the plasma half-life of DiI in sCPM was 19.3 h. The relative accumulation concentration in tumor of DiI delivered by sCPM was 2.37-fold higher than that of PLA-PEG, at 4 h after intravenous injection. These results demonstrated that the star-branched copolymer (PLA-b-PMPC{sub 3}){sub 3} is a promising alternative carrier material for intravenous delivery versus classic PEG-modified strategies. - Highlights: • Star-branched amphiphilic copolymer micelles (sCPM) with zwitterionic shells were prepared. • sCPM possess an ultra-hydrophilic surface and thus inhibited the protein absorption. • sCPM can effectively prolong the cargo’s plasma circulation time. • sCPM can enhance the cargo’s passive tumor-targeted delivery.

  9. Synthesis of Zn{sub 1−x}Co{sub x}Fe{sub 2}O{sub 4}/MWCNTs nanocomposites using reverse micelle method: Investigation of their structural, magnetic, electrical, optical and photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Charanjit [Department of Chemistry, Panjab University, Chandigarh 160 014 (India); Bansal, Sandeep [DST, New Delhi (India); Singhal, Sonal, E-mail: sonal1174@gmail.com [Department of Chemistry, Panjab University, Chandigarh 160 014 (India)

    2014-07-01

    Zn{sub 1−x}Co{sub x}Fe{sub 2}O{sub 4}/MWCNTs (x=0.0, 0.2, 0.4, 0.6 and 0.8) nanocomposites have been synthesized via reverse micelle method using functionalized carbon nanotubes. Powder X-ray Diffraction (XRD) patterns revealed the cubic spinel structure with Fd-3m space group without interfering the peak of CNTs. The fundamental Raman scattering peaks at 310, 460 and 662 cm{sup −1} have been observed due to different vibrational frequencies of Fe{sup 3+}, Co{sup 2+} and Zn{sup 2+} cations. Transmission Electron Micrographs (TEM) confirmed the attachment of nanoferrite particles on the surface of negatively charged CNTs. The saturation magnetization increased with Co{sup 2+} doping, however, no pronounced value of coercivity has been observed suggesting the superparamagnetic character. An increase in conductivity with increase in cobalt ion doping has been observed due to increase in hopping of electron between Co{sup 2+}–Co{sup 3+} ion pair. ZnFe{sub 2}O{sub 4}/MWCNTs composite has been found the best suitable visible light driven catalyst for the degradation of Rodhamine B (50 µM) with upto 99% in 5 h.

  10. Amyloid Beta Peptide Folding in Reverse Micelles.

    Science.gov (United States)

    Eskici, Gözde; Axelsen, Paul H

    2017-07-19

    Previously published experimental studies have suggested that when the 40-residue amyloid beta peptide is encapsulated in a reverse micelle, it folds into a structure that may nucleate amyloid fibril formation (Yeung, P. S.-W.; Axelsen, P. H. J. Am. Chem. Soc. 2012, 134, 6061 ). The factors that induce the formation of this structure have now been identified in a multi-microsecond simulation of the same reverse micelle system that was studied experimentally. Key features of the polypeptide-micelle interaction include the anchoring of a hydrophobic residue cluster into gaps in the reverse micelle surface, the formation of a beta turn at the anchor point that brings N- and C-terminal segments of the polypeptide into proximity, high ionic strength that promotes intramolecular hydrogen bond formation, and deformation of the reverse micelle surface to facilitate interactions with the surface along the entire length of the polypeptide. Together, these features cause the simulation-derived vibrational spectrum to red shift in a manner that reproduces the red-shift previously reported experimentally. On the basis of these findings, a new mechanism is proposed whereby membranes nucleate fibril formation and facilitate the in-register alignment of polypeptide strands that is characteristic of amyloid fibrils.

  11. Rearrangement of micelle structures during polymerization

    International Nuclear Information System (INIS)

    Chatjaroenporn, K.; Baker, R.; FitzGerald, P.; Warr, G.

    2009-01-01

    Full text: Using small angle neutron scattering (SANS), we studied the shape transition of micelles of 11(methacryloyloxy)undecyltrimethylammonium bromide (MUTAB) as this tail-polymerisable cationic surfactant polymerized. Previous studies of such systems have suggested kinetic 'locking' of the micelle structure during polymerization. However, we found a transition from spheres (unpolymerised) to rods (at intermediate conversions) back to spheres (fully polymerized), see Figure 1. By comparing these results to the micelle shapes formed by the mixtures of 100% polymerized and unpolymerised MUTAB, we show that the shape transitions observed during polymerization are due to equilibrium structures that undergo rearrangement as the composition changes. In addition, atomic force microscopy (AFM) reveals that besides the monolayer of unpolymerised MUTAB, the rearranged structures of this surfmer in bulk, when polymerization proceeded, retained their shapes after adsorbing at mica/solution interface, providing potential for the manipulating of thin film structures. This understanding assists design of templating or encapsulating nanostructured materials.

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

    African Journals Online (AJOL)

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

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

    NARCIS (Netherlands)

    Yan, Y.; Keizer, de A.; Cohen Stuart, M.A.; Drechsler, M.; Besseling, N.A.M.

    2008-01-01

    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

  14. Estimation of interfacial acidity of sodium dodecyl sulfate micelles

    Indian Academy of Sciences (India)

    on various molecules in micro-heterogeneous media such as micelles,3 cyclodextrins4 and polymer-micelle ... of the micro-heterogenous media such as sodium dode- cyl sulfate (SDS) micelles to enhance the ESPT ...... tations. AD thanks Council of Scientific and Indus- trial Research, New Delhi (CSIR) for junior research.

  15. 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.

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

    Science.gov (United States)

    Nagarajan, Ramanathan

    2015-07-01

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

  17. DNA-based Artificial Nanostructures: Fabrication, Properties, and Applications

    OpenAIRE

    Sun, Young; Kiang, Ching-Hwa

    2005-01-01

    Table of Content 1. Introduction 2. DNA fundamentals 3. Attachment of DNA to surface 4. Fabrication of nanostructures using DNA 4.1 Nanostructures of pure DNA 4.2 DNA-based assembly of metal nanoparticles 4.3 Construction of semiconductor particle arrays using DNA 4.4 DNA-directed nanowires 4.5 DNA-functionalized carbon nanotubes 4.6 Field-transistor based on DNA 4.7 Nanofabrication using artificial DNA 5. DNA-based nanostructures as biosensors 6. Properties of DNA-linked gold nanoparticles 6...

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

    International Nuclear Information System (INIS)

    Ray, D.; Aswal, V. K.

    2015-01-01

    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

  19. 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.

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

    Science.gov (United States)

    Ray, D.; Aswal, V. K.

    2015-06-01

    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.

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

    OpenAIRE

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

    2013-01-01

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

  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. Co-assembly towards Janus micelles

    NARCIS (Netherlands)

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

    2011-01-01

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

  4. Micelle-encapsulated fullerenes in aqueous electrolytes

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-15

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

  5. Hyaluronan polymeric micelles for topical drug delivery

    Czech Academy of Sciences Publication Activity Database

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

    2017-01-01

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

  6. Spontaneous symmetry breaking: formation of Janus micelles

    NARCIS (Netherlands)

    Voets, I.K.; Fokkink, R.G.; Hellweg, T.; King, S.M.; Waard, de P.; Keizer, de A.; Cohen Stuart, M.A.

    2009-01-01

    We describe the preparation and solution properties of Janus micelles, i.e., non-centrosymmetric nanoparticles with compartmentalized shells, via co-assembly of two fully water-soluble block copolymers. They consist of a mixed core of poly(N-methyl-2-vinyl pyridinium iodide) (P2MVP) and poly(acrylic

  7. Colloidal Electrolytes and the Critical Micelle Concentration

    Science.gov (United States)

    Knowlton, L. G.

    1970-01-01

    Describes methods for determining the Critical Micelle Concentration of Colloidal Electrolytes; methods described are: (1) methods based on Colligative Properties, (2) methods based on the Electrical Conductivity of Colloidal Electrolytic Solutions, (3) Dye Method, (4) Dye Solubilization Method, and (5) Surface Tension Method. (BR)

  8. POLYMER MICELLE INTERACTIONS - PHYSICAL ORGANIC ASPECTS

    NARCIS (Netherlands)

    Brackman, J C; Engberts, J B F N

    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

  9. Temperature Effect on the Nanostructure of SDS Micelles in Water.

    Science.gov (United States)

    Hammouda, Boualem

    2013-01-01

    Sodium dodecyl sulfate (SDS) surfactants form micelles when dissolved in water. These are formed of a hydrocarbon core and hydrophilic ionic surface. The small-angle neutron scattering (SANS) technique was used with deuterated water (D2O) in order to characterize the micelle structure. Micelles were found to be slightly compressed (oblate ellipsoids) and their sizes shrink with increasing temperature. Fits of SANS data to the Mean Spherical Approximation (MSA) model yielded a calculated micelle volume fraction which was lower than the SDS surfactant (sample mixing) volume fraction; this suggests that part of the SDS molecules do not participate in micelle formation and remain homogeneously mixed in the solvent. A set of material balance equations allowed the estimation of the SDS fraction in the micelles. This fraction was found to be high (close to one) except for samples around 1 % SDS fraction. The micelle aggregation number was found to decrease with increasing temperature and/or decreasing SDS fraction.

  10. Role of noble metal nanoparticles in DNA base damage and catalysis: a radiation chemical investigation

    International Nuclear Information System (INIS)

    Sharma, Geeta K.

    2011-01-01

    In the emerging field of nanoscience and nanotechnology, tremendous focus has been made by researcher to explore the applications of nanomaterials for human welfare by converting the findings into technology. Some of the examples have been the use of nanoparticles in the field of opto-electronic, fuel cells, medicine and catalysis. These wide applications and significance lies in the fact that nanoparticles possess unique physical and chemical properties very different from their bulk precursors. Numerous methods for the synthesis of noble nanoparticles with tunable shape and size have been reported in literature. The goal of our group is to use different methods of synthesis of noble metal nanoparticles (Au, Ag, Pt and Pd) and test their protective/damaging role towards DNA base damage induced by ionizing radiation (Au and Ag) and to test the catalytic activity of nanoparticles (Pt and Pd) in certain known organic synthesis/electron transfer reactions. Using radiation chemical techniques such as pulse radiolysis and steady state radiolysis complemented by the product analysis using HPLC/LC-MS, a detailed mechanism for the formation of transient species, kinetics leading to the formation of stable end products is studied in the DNA base damage induced by ionizing radiation in presence and absence of Au and Ag nanoparticles. Unraveling the complex interaction between catalysts and reactants under operando conditions is a key step towards gaining fundamental insight in catalysis. The catalytic activity of Pt and Pd nanoparticles in electron transfer and Suzuki coupling reactions has been determined. Investigations are currently underway to gain insight into the interaction between catalysts and reactants using time resolved spectroscopic measurements. These studies will be detailed during the presentation. (author)

  11. Development and in vivo quantitative magnetic resonance imaging of polymer micelles targeted to the melanocortin 1 receptor.

    Science.gov (United States)

    Barkey, Natalie M; Preihs, Christian; Cornnell, Heather H; Martinez, Gary; Carie, Adam; Vagner, Josef; Xu, Liping; Lloyd, Mark C; Lynch, Vincent M; Hruby, Victor J; Sessler, Jonathan L; Sill, Kevin N; Gillies, Robert J; Morse, David L

    2013-08-22

    Recent emphasis has focused on the development of rationally designed polymer-based micelle carriers for drug delivery. The current work tests the hypothesis that target specificity can be enhanced by micelles with cancer-specific ligands. In particular, we describe the synthesis and characterization of a new gadolinium texaphyrin (Gd-Tx) complex encapsulated in an IVECT micellar system, stabilized through Fe(III) cross-linking and targeted with multiple copies of a specific ligand for the melanocortin 1 receptor (MC1R), which has been evaluated as a cell-surface marker for melanoma. On the basis of comparative MRI experiments, we have been able to demonstrate that these Gd-Tx micelles are able to target MC1R-expressing xenograft tumors in vitro and in vivo more effectively than various control systems, including untargeted or un-cross-linked Gd-Tx micelles. Taken in concert, the findings reported herein support the conclusion that appropriately designed micelles are able to deliver contrast agent payloads to tumors expressing the MC1R.

  12. 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.

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

    Science.gov (United States)

    Meng, Bin; Ashbaugh, Henry S

    2015-03-24

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

  14. Controlling charge current through a DNA based molecular transistor

    Energy Technology Data Exchange (ETDEWEB)

    Behnia, S., E-mail: s.behnia@sci.uut.ac.ir; Fathizadeh, S.; Ziaei, J.

    2017-01-05

    Molecular electronics is complementary to silicon-based electronics and may induce electronic functions which are difficult to obtain with conventional technology. We have considered a DNA based molecular transistor and study its transport properties. The appropriate DNA sequence as a central chain in molecular transistor and the functional interval for applied voltages is obtained. I–V characteristic diagram shows the rectifier behavior as well as the negative differential resistance phenomenon of DNA transistor. We have observed the nearly periodic behavior in the current flowing through DNA. It is reported that there is a critical gate voltage for each applied bias which above it, the electrical current is always positive. - Highlights: • Modeling a DNA based molecular transistor and studying its transport properties. • Choosing the appropriate DNA sequence using the quantum chaos tools. • Choosing the functional interval for voltages via the inverse participation ratio tool. • Detecting the rectifier and negative differential resistance behavior of DNA.

  15. 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...

  16. Thermoresponsive polymer micelles as potential nanosized cancerostatics

    Czech Academy of Sciences Publication Activity Database

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

    2015-01-01

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

  17. SANS study of coated block copolymer micelles

    Czech Academy of Sciences Publication Activity Database

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

    2005-01-01

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

  18. 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.

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

    International Nuclear Information System (INIS)

    Talele, Paurnima; Choudhary, Sinjan; Kishore, Nand

    2016-01-01

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

  20. 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....

  1. Self-assembled or mixed peptide amphiphile micelles from Herpes simplex virus glycoproteins as potential immunomodulatory treatment.

    Science.gov (United States)

    Accardo, Antonella; Vitiello, Mariateresa; Tesauro, Diego; Galdiero, Marilena; Finamore, Emiliana; Martora, Francesca; Mansi, Rosalba; Ringhieri, Paola; Morelli, Giancarlo

    2014-01-01

    The use of micelle aggregates formed from peptide amphiphiles (PAs) as potential synthetic self-adjuvant vaccines to treat Herpes simplex virus (HSV) infection are reported here. The PAs were based on epitopes gB409-505 and gD301-309, selected from HSV envelope glycoprotein B (gB) and glycoprotein D (gD), that had their N-terminus modified with hydrophobic moieties containing two C18 hydrocarbon chains. Pure and mixed micelles of gB and/or gD peptide epitopes were easily prepared after starting with the synthesis of corresponding PAs by solid phase methods. Structural characterization of the aggregates confirmed that they were sufficiently stable and compatible with in vivo use: critical micelle concentration values around 4.0 ⋅ 10(-7) mol ⋅ Kg(-1); hydrodynamic radii (RH) between 50-80 nm, and a zeta potential (ζ) around - 40 mV were found for all aggregates. The in vitro results indicate that both peptide epitopes and micelles, at 10 μM, triggered U937 and RAW 264.7 cells to release appreciable levels of cytokines. In particular, interleukin (IL)-23-, IL-6-, IL-8- or macrophage inflammatory protein (MIP)-2-, and tumor necrosis factor (TNF)-α-release increased considerably when cells were treated with the gB-micelles or gD-micelles compared with the production of the same cytokines when the stimulus was the single gB or gD peptide.

  2. Diclofenac/biodegradable polymer micelles for ocular applications

    Science.gov (United States)

    Li, Xingyi; Zhang, Zhaoliang; Li, Jie; Sun, Shumao; Weng, Yuhua; Chen, Hao

    2012-07-01

    In this paper, methoxypoly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelle formulations as promising nano-carriers for poorly water soluble drugs were investigated for the delivery of diclofenac to the eye. Diclofenac loaded MPEG-PCL micelles were prepared by a simple solvent-diffusion method and characterized by dynamic light scattering (DLS), atomic force microscopy (AFM), Fourier transform infra-red (FTIR), X-ray diffraction (XRD), differential scanning calorimetery (DSC), etc. With the analysis of XRD and DSC, the diclofenac was present as an amorphous state in the formulation. The in vitro release profile indicated a sustained release manner of diclofenac from the micelles. Meanwhile, in vivo studies on eye irritation were performed with blank MPEG-PCL micelles (200 mg ml-1). The results showed that the developed MPEG-PCL micelles were non-irritants to the eyes of rabbits. In vitro penetration studies across the rabbit cornea demonstrated that the micelle formulations exhibited a 17-fold increase in penetration compared with that of diclofenac phosphate buffered saline (PBS) solution. The in vivo pharmacokinetics profile of the micelle parent drug in the aqueous humor of the rabbit was evaluated and the data showed that the diclofenac loaded MPEG-PCL micelles exhibited a 2-fold increase in AUC0-24 h than that of the diclofenac PBS solution eye drops. These results suggest a great potential of our micelle formulations as a novel ocular drug delivery system to improve the bioavailability of the drugs.

  3. Stereocomplex-Reinforced PEGylated Polylactide Micelle for Optimized Drug Delivery

    Directory of Open Access Journals (Sweden)

    Chunsheng Feng

    2016-04-01

    Full Text Available The instability of PEGylated polylactide micelles is a challenge for drug delivery. Stereocomplex interaction between racemic polylactide chains with different configurations provides an effective strategy to enhance the stability of micelles as the nanocarriers of drugs. In this work, a stereocomplex micelle (SCM self-assembled from the amphiphilic triblock copolymers comprising poly(ethylene glycol (PEG, and dextrorotatory and levorotatory polylactides (PDLA and PLLA was applied for efficient drug delivery. The spherical SCM showed the smallest scale and the lowest critical micelle concentration (CMC than the micelles with single components attributed to the stereocomplex interaction between PDLA and PLLA. 10-Hydroxycamptothecin (HCPT as a model antitumor drug was loaded into micelles. Compared with the loading micelles from individual PDLA and PLLA, the HCPT-loaded SCM exhibited the highest drug loading efficiency (DLE and the slowest drug release in phosphate-buffered saline (PBS at pH 7.4, indicating its enhanced stability in circulation. More fascinatingly, the laden SCM was demonstrated to have the highest cellular uptake of HCPT and suppress malignant cells most effectively in comparison to the HCPT-loaded micelles from single copolymer. In summary, the stereocomplex-enhanced PLA–PEG–PLA micelle may be promising for optimized drug delivery in the clinic.

  4. Brij-micelle and polyacrylic acid interaction investigated by Cu 2+-induced pyrene fluorescence: Effect of brij-micelle structure

    Science.gov (United States)

    Bandyopadhyay, Prasun; Ghosh, Amit K.; Bandyopadhyay, Sayan

    2009-07-01

    Fluorescence response of pyrene has been studied in the presence of polyacrylic acid (PAA) and brij surfactant micelles with Cu 2+ as an ionic quencher. The quenched pyrene emission is completely recovered with the addition of PAA (conc. 2.4 × 10 -4 M) for brij 35 (poly-oxyethylene-23 lauryl ether) micelle indicating PAA-Cu 2+ complex formation at the micelle-water interface. This could be due to the relatively easier accessibility of PAA polymer chains near poly-oxyethylene chain of brij 35 micelle compared to brij 30 (poly-oxyethylene-4 lauryl ether) micelle. The interaction between brij-micelle and polymer is confirmed by turbidimetry and NMR spectroscopy.

  5. First synthesis of phosphonobile acids and preliminary studies on their aggregation properties.

    Science.gov (United States)

    Maitra, Uday; Babu, Ponnusamy

    2003-05-01

    The synthesis of three novel phosphonobile acids from natural bile acids is reported. The CMC of phosphonodeoxycholic acid (PDCA) at pH 8.2 was found to be lower than that of the parent deoxycholic acid (DCA). PDCA micelles were also found to have higher microviscosity compared to DCA micelles, suggesting higher hydrophobicity and tighter packing in the interior of PDCA micelles. PDCA aggregated further to form an aqueous gel at pH 4.

  6. Effect of Polymer Micelles on Antifungal Activity of Geranylorcinol Compounds against Botrytis cinerea.

    Science.gov (United States)

    Taborga, Lautaro; Díaz, Katy; Olea, Andrés F; Reyes-Bravo, Paula; Flores, Mario E; Peña-Cortés, Hugo; Espinoza, Luis

    2015-08-12

    Herein, we explore the potential use of two micelle-forming block copolymers, i.e., Pluronic F-127 and poly(ethylene oxide)-b-poly(caprolactone), for application of fungicide agents. The polymer effect on the in vitro fungicide activity of a series of geranyl orcinol derivatives against Botrytis cinerea has been assessed. The results show that, for all test compounds, the incorporation into micelles, formed by Pluronic F-127, produces a great enhancement of the inhibitory effect on the growth of B. cinerea. For some compounds, at the lowest tested concentration (50 ppm), the percentage of inhibition increases significantly (from 0-10 to 80-90%) when the application is made using a polymer solution instead of an ethanol/water mixture. The synthesis and structural determination of a series of eight geranylphenols/diacetates, which were used as fungicide agents, are also discussed. These results suggest that polymer micelles are promising systems for application of crop-protecting agents.

  7. Star polymer-based unimolecular micelles and their application in bio-imaging and diagnosis.

    Science.gov (United States)

    Jin, Xin; Sun, Pei; Tong, Gangsheng; Zhu, Xinyuan

    2018-02-03

    As a novel kind of polymer with covalently linked core-shell structure, star polymers behave in nanostructure in aqueous medium at all concentration range, as unimolecular micelles at high dilution condition and multi-micelle aggregates in other situations. The unique morphologies endow star polymers with excellent stability and functions, making them a promising platform for bio-application. A variety of functions including imaging and therapeutics can be achieved through rational structure design of star polymers, and the existence of plentiful end-groups on shell offers the opportunity for further modification. In the last decades, star polymers have become an attracting platform on fabrication of novel nano-systems for bio-imaging and diagnosis. Focusing on the specific topology and physicochemical properties of star polymers, we have reviewed recent development of star polymer-based unimolecular micelles and their bio-application in imaging and diagnosis. The main content of this review summarizes the synthesis of integrated architecture of star polymers and their self-assembly behavior in aqueous medium, focusing especially on the recent advances on their bio-imaging application and diagnosis use. Finally, we conclude with remarks and give some outlooks for further exploration in this field. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Micelle-hosted palladium nanoparticles catalyze citral molecule hydrogenation in supercritical carbon dioxide.

    Science.gov (United States)

    Meric, Pascal; Yu, Kai Man K; Tsang, Shik Chi

    2004-09-28

    A new approach of employing metal particles in micelles for the hydrogenation of organic molecules in the presence of fluorinated surfactant and water in supercritical carbon dioxide has very recently been introduced. This is allegedly to deliver many advantages for carrying out catalysis including the use of supercritical carbon dioxide (scCO2) as a greener solvent. Following this preliminary account, the present work aims to provide direct visual evidence on the formation of metal microemulsions and to investigate whether metal located in the soft micellar assemblies could affect reaction selectivity. Synthesis of Pd nanoparticles in perfluorohydrocarboxylate anionic micelles in scCO2 is therefore carried out in a stainless steel batch reactor at 40 degrees C and in a 150 bar CO2/H2 mixture. Homogeneous dispersion of the microemulsion containing Pd nanoparticles in scCO2 is observed through a sapphire window reactor at W0 ratios (molar water-to-surfactant ratios) ranging from 2 to 30. It is also evidenced that the use of micelle assemblies as new metal catalyst nanocarriers could indeed exert a great influence on product selectivity. The hydrogenation of a citral molecule that contains three reducible groups (aldehyde, double bonds at the 2,3-position and the 6,7-position) is studied. An unusually high selectivity toward citronellal (a high regioselectivity toward the reduction of the 2,3-unsaturation) is observed in supercritical carbon dioxide. On the other hand, when the catalysis is carried out in the conventional liquid or vapor phase over the same reaction time, total hydrogenation of the two double bonds is achieved. It is thought that the high kinetic reluctance for double bond hydrogenation of the citral molecule at the hydrophobic end (the 6,7-position) is due to the unique micelle environment that is in close proximity to the metal surface in supercritical carbon dioxide that guides a head-on attack of the molecule toward the core metal particle.

  9. Inverted Micelle-in-Micelle Configuration in Cationic/Carbohydrate Surfactant Mixtures.

    Science.gov (United States)

    Das, Saikat; Xu, Wenjin; Lehmler, Hans-Joachim; Miller, Anne-Frances; Knutson, Barbara L; Rankin, Stephen E

    2017-01-04

    Nuclear magnetic resonance is applied to investigate the relative positions and interactions between cationic and non-ionic carbohydrate-based surfactants in mixed micelles with D 2 O as the solvent. This is accomplished by using relaxation measurements [spin-lattice (T 1 ) and spin-spin (T 2 ) analysis] and nuclear Overhauser effect spectroscopy (NOESY). This study focuses on the interactions of n-octyl β-d-glucopyranoside (C8G1) and β-d-xylopyranoside (C8X1) with the cationic surfactant hexadecyltrimethylammonium bromide (C 16 TAB). Whereas the interactions between carbohydrate and cationic surfactants are thermodynamically favorable, the NOESY results suggest that both of the sugar head groups are located preferentially at the interior core of the mixed micelles, so that they are not directly exposed to the bulk solution. The more hydrophilic sugar headgroups of C8G1 have more mobility than sugar heads of C8X1 owing to increased hydration. Herein, an inverted carbohydrate configuration in mixed micelles is proposed for the first time and supported by fluorescence spectroscopy experiments. This inverted carbohydrate headgroup configuration would limit the use of these mixed surfactants when access to the carbohydrate headgroup is important, but may present new opportunities where the carbohydrate-rich core of the micelles can be exploited. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. The thermal signature of wormlike micelles

    International Nuclear Information System (INIS)

    Ito, Thiago Heiji; Clinckspoor, Karl Jan; Nunes de Souza, Renato; Sabadini, Edvaldo

    2016-01-01

    Highlights: • Giant micelle formation has a characteristic exothermic profile, for these systems. • The enthalpy of formation is dependent on the planarity of the co-solute. • The affinity is dependent on the enthalpy and critical concentration of the species. • The higher the affinity, the higher thermal stability and size of the micelles. - Abstract: The variations in enthalpy (Δ f H WLM ) and critical concentrations associated with the formation of wormlike micelles (WLMs) from combinations of tetradecyltrimethylammonium bromide (C 14 TAB) and various aromatic co-solutes were determined using isothermal titration calorimetry (ITC). Three groups of aromatic molecules were investigated: neutral (phenol), benzoate derivatives and cinnamate derivatives. In addition, the thermal stabilities of the WLMs (of hexadecyltrimethylammonium bromide, C 16 TAB) and the aromatic co-solutes of the three groups were investigated by measuring the temperatures at which the WLMs break and lose their ability to produce hydrodynamic drag reduction. A comparison of the results was used to establish correlations between the spontaneity of WLMs formation, their thermal stability and the molecular structure of the aromatic co-solutes. A characteristic thermal pattern with four steps was observed when WLMs are formed, that depended on the co-solute structure. Micellar growth was found to be an exothermic process, related to the fusion of the end caps allied with the incorporation of more co-solutes. The co-solutes that had negative charge and were able to maintain planar configuration demonstrated stronger interactions and also showed higher thermal stability through drag reduction.

  11. Treating acute cystitis with biodegradable micelle-encapsulated quercetin

    Science.gov (United States)

    Wang, Bi Lan; Gao, Xiang; Men, Ke; Qiu, Jinfeng; Yang, Bowen; Gou, Ma Ling; Huang, Mei Juan; Huang, Ning; Qian, Zhi Yong; Zhao, Xia; Wei, Yu Quan

    2012-01-01

    Intravesical application of an anti-inflammatory drug is an efficient strategy for acute cystitis therapy. Quercetin (QU) is a potent anti-inflammatory agent; however, its poor water solubility restricts its clinical application. In an attempt to improve water solubility of QU, biodegradable monomethoxy poly(ethylene glycol)-poly(ɛ-caprolactone) (MPEG-PCL) micelles were used to encapsulate QU by self-assembly methods, creating QU/MPEG-PCL micelles. These QU/MPEG-PCL micelles with DL of 7% had a mean particle size of <34 nm, and could release QU for an extended period in vitro. The in vivo study indicated that intravesical application of MPEG-PCL micelles did not induce any toxicity to the bladder, and could efficiently deliver cargo to the bladder. Moreover, the therapeutic efficiency of intravesical administration of QU/MPEG-PCL micelles on acute cystitis was evaluated in vivo. Results indicated that QU/MPEG-PCL micelle treatment efficiently reduced the edema and inflammatory cell infiltration of the bladder in an Escherichia coli-induced acute cystitis model. These data suggested that MPEG-PCL micelle was a candidate intravesical drug carrier, and QU/MPEG-PCL micelles may have potential application in acute cystitis therapy. PMID:22661886

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

    African Journals Online (AJOL)

    Erah

    and, not infrequently, the low water solubility of the carrier itself, can easily result in the precipitation of the polymer derivative, and often does 5, 6, 7, 8. To overcome this problem, a promising technique is to make polymer drugs that take the form of micelles 5, 6, 7, 8. In line with this approach, micelle-forming polymer.

  13. Pressure-induced structural transition of nonionic micelles

    Indian Academy of Sciences (India)

    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. Keywords. Micelles; dynamic light scattering, small angle neutron scattering.

  14. 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

  15. 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

  16. 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)

  17. 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

  18. Characterization of Phospholipid Mixed Micelles by Translational Diffusion

    International Nuclear Information System (INIS)

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

    2004-01-01

    The concentration dependence of the translational self diffusion rate, D s , has been measured for a range of micelle and mixed micelle systems. Use of bipolar gradient pulse pairs in the longitudinal eddy current delay experiment minimizes NOE attenuation and is found critical for optimizing sensitivity of the translational diffusion measurement of macromolecules and aggregates. For low volume fractions Φ (Φ ≤ 15% v/v) of the micelles, experimental measurement of the concentration dependence, combined with use of the D s =D o (1-3.2λΦ) relationship, yields the hydrodynamic volume. For proteins, the hydrodynamic volume, derived from D s at infinitely dilute concentration, is found to be about 2.6 times the unhydrated molecular volume. Using the data collected for hen egg white lysozyme as a reference, diffusion data for dihexanoyl phosphatidylcholine (DHPC) micelles indicate approximately 27 molecules per micelle, and a critical micelle concentration of 14 mM. Differences in translational diffusion rates for detergent and long chain phospholipids in mixed micelles are attributed to rapid exchange between free and micelle-bound detergent. This difference permits determination of the free detergent concentration, which, for a high detergent to long chain phospholipid molar ratio, is found to depend strongly on this ratio. The hydrodynamic volume of DHPC/POPC bicelles, loaded with an M2 channel peptide homolog, derived from translational diffusion, predicts a rotational correlation time that slightly exceeds the value obtained from peptide 15 N relaxation data

  19. The current state of eukaryotic DNA base damage and repair.

    Science.gov (United States)

    Bauer, Nicholas C; Corbett, Anita H; Doetsch, Paul W

    2015-12-02

    DNA damage is a natural hazard of life. The most common DNA lesions are base, sugar, and single-strand break damage resulting from oxidation, alkylation, deamination, and spontaneous hydrolysis. If left unrepaired, such lesions can become fixed in the genome as permanent mutations. Thus, evolution has led to the creation of several highly conserved, partially redundant pathways to repair or mitigate the effects of DNA base damage. The biochemical mechanisms of these pathways have been well characterized and the impact of this work was recently highlighted by the selection of Tomas Lindahl, Aziz Sancar and Paul Modrich as the recipients of the 2015 Nobel Prize in Chemistry for their seminal work in defining DNA repair pathways. However, how these repair pathways are regulated and interconnected is still being elucidated. This review focuses on the classical base excision repair and strand incision pathways in eukaryotes, considering both Saccharomyces cerevisiae and humans, and extends to some important questions and challenges facing the field of DNA base damage repair. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  20. Main features of DNA-based immunization vectors

    Directory of Open Access Journals (Sweden)

    V. Azevedo

    1999-02-01

    Full Text Available DNA-based immunization has initiated a new era of vaccine research. One of the main goals of gene vaccine development is the control of the levels of expression in vivo for efficient immunization. Modifying the vector to modulate expression or immunogenicity is of critical importance for the improvement of DNA vaccines. The most frequently used vectors for genetic immunization are plasmids. In this article, we review some of the main elements relevant to their design such as strong promoter/enhancer region, introns, genes encoding antigens of interest from the pathogen (how to choose and modify them, polyadenylation termination sequence, origin of replication for plasmid production in Escherichia coli, antibiotic resistance gene as selectable marker, convenient cloning sites, and the presence of immunostimulatory sequences (ISS that can be added to the plasmid to enhance adjuvanticity and to activate the immune system. In this review, the specific modifications that can increase overall expression as well as the potential of DNA-based vaccination are also discussed.

  1. A DNA-based semantic fusion model for remote sensing data.

    Science.gov (United States)

    Sun, Heng; Weng, Jian; Yu, Guangchuang; Massawe, Richard H

    2013-01-01

    Semantic technology plays a key role in various domains, from conversation understanding to algorithm analysis. As the most efficient semantic tool, ontology can represent, process and manage the widespread knowledge. Nowadays, many researchers use ontology to collect and organize data's semantic information in order to maximize research productivity. In this paper, we firstly describe our work on the development of a remote sensing data ontology, with a primary focus on semantic fusion-driven research for big data. Our ontology is made up of 1,264 concepts and 2,030 semantic relationships. However, the growth of big data is straining the capacities of current semantic fusion and reasoning practices. Considering the massive parallelism of DNA strands, we propose a novel DNA-based semantic fusion model. In this model, a parallel strategy is developed to encode the semantic information in DNA for a large volume of remote sensing data. The semantic information is read in a parallel and bit-wise manner and an individual bit is converted to a base. By doing so, a considerable amount of conversion time can be saved, i.e., the cluster-based multi-processes program can reduce the conversion time from 81,536 seconds to 4,937 seconds for 4.34 GB source data files. Moreover, the size of result file recording DNA sequences is 54.51 GB for parallel C program compared with 57.89 GB for sequential Perl. This shows that our parallel method can also reduce the DNA synthesis cost. In addition, data types are encoded in our model, which is a basis for building type system in our future DNA computer. Finally, we describe theoretically an algorithm for DNA-based semantic fusion. This algorithm enables the process of integration of the knowledge from disparate remote sensing data sources into a consistent, accurate, and complete representation. This process depends solely on ligation reaction and screening operations instead of the ontology.

  2. Allosterically tunable, DNA-based switches triggered by heavy metals.

    Science.gov (United States)

    Porchetta, Alessandro; Vallée-Bélisle, Alexis; Plaxco, Kevin W; Ricci, Francesco

    2013-09-11

    Here we demonstrate the rational design of allosterically controllable, metal-ion-triggered molecular switches. Specifically, we designed DNA sequences that adopt two low energy conformations, one of which does not bind to the target ion and the other of which contains mismatch sites serving as specific recognition elements for mercury(II) or silver(I) ions. Both switches contain multiple metal binding sites and thus exhibit homotropic allosteric (cooperative) responses. As heterotropic allosteric effectors we employ single-stranded DNA sequences that either stabilize or destabilize the nonbinding state, enabling dynamic range tuning over several orders of magnitude. The ability to rationally introduce these effects into target-responsive switches could be of value in improving the functionality of DNA-based nanomachines.

  3. A Rewritable, Random-Access DNA-Based Storage System

    Science.gov (United States)

    Tabatabaei Yazdi, S. M. Hossein; Yuan, Yongbo; Ma, Jian; Zhao, Huimin; Milenkovic, Olgica

    2015-09-01

    We describe the first DNA-based storage architecture that enables random access to data blocks and rewriting of information stored at arbitrary locations within the blocks. The newly developed architecture overcomes drawbacks of existing read-only methods that require decoding the whole file in order to read one data fragment. Our system is based on new constrained coding techniques and accompanying DNA editing methods that ensure data reliability, specificity and sensitivity of access, and at the same time provide exceptionally high data storage capacity. As a proof of concept, we encoded parts of the Wikipedia pages of six universities in the USA, and selected and edited parts of the text written in DNA corresponding to three of these schools. The results suggest that DNA is a versatile media suitable for both ultrahigh density archival and rewritable storage applications.

  4. Ultraviolet enhancement of DNA base release by bleomycin

    International Nuclear Information System (INIS)

    Kakinuma, J.; Tanabe, M.; Orii, H.

    1984-01-01

    The effect of UV irradiation on base-releasing activity of bleomycin was studied on bleomycin A 2 -DNA reaction mixture in the presence of Fe(II) and 2-mercaptoethanol. This effect was measured by the release of free bases from calf thymus DNA with high-performance liquid chromatography. UV irradiation enhanced DNA base-releasing activity of bleomycin and simultaneously caused disappearance of fluorescence emission maximum at 355 nm assigned to bithiazole rings and increase in the intensity of a peak at 400 nm. UV irradiation at 295 nm, the UV absorption maximum of bleomycin, is the most effective in releasing free bases and in changing fluorescence emission patterns. From these results, we suggest that some alterations in the bithiazole group of bleomycin molecule were initiated by UV irradiation and contributed to increased base-releasing activity of bleomycin through a yet unexplained mechanism, presumably through bleomycin dimer formation. (orig.)

  5. Lamellar Micelles - Mediated Synthesis of Nanoscale Thick Sheets of Titania

    Czech Academy of Sciences Publication Activity Database

    Klusoň, P.; Lusková, H.; Šolcová, Olga; Matějová, Lenka; Cajthaml, Tomáš

    2007-01-01

    Roč. 61, 14-15 (2007), s. 2931-2934 ISSN 0167-577X R&D Projects: GA ČR(CZ) GA104/04/0963; GA ČR(CZ) GD203/03/H140 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z50200510 Keywords : nanostructures * lamellar titania * templating Subject RIV: CA - Inorganic Chemistry Impact factor: 1.625, year: 2007

  6. Synthesis of nanocrystalline materials through reverse micelles: A ...

    Indian Academy of Sciences (India)

    Wintec

    organic solvent) (spectrochem) and aqueous solution were prepared. One microemulsion contained 0⋅1 M Ce(NO3)3⋅6H2O solution, 0⋅1 M zirconyl oxychloride and 0⋅1 M zinc nitrate solution for cerium oxalate, zirconium oxalate and zinc ...

  7. Synthesis of nanocrystalline materials through reverse micelles: A ...

    Indian Academy of Sciences (India)

    Wintec

    of Science and Technology, Govt. of India, for financial support. (TA) and (SV) thank CSIR, Govt. of India, for fellowships. The authors also thank Dr Subhasis Ghosh,. JNU, for the optical studies. References. Ahmad T and Ganguli A K 2006 J. Am. Ceram. Soc. 89 1326. Ahmad T, Ramanujachary K V, Lofland S E and Ganguli ...

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

    Science.gov (United States)

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

    2013-08-01

    Hydration waters impact protein dynamics. Dissecting the interplay between hydration waters and dynamics requires a protein that manifests a broad range of dynamics. Proteins in reverse micelles (RMs) have promise as tools to achieve this objective because the water content can be manipulated. Hemoglobin is an appropriate tool with which to probe hydration effects. We describe both a protocol for hemoglobin encapsulation in reverse micelles and a facile method using PEG and cosolvents to manipulate water content. Hydration properties are probed using the water-sensitive fluorescence from Hb bound pyranine and covalently attached Badan. Protein dynamics are probed through ligand recombination traces derived from photodissociated carbonmonoxy hemoglobin on a log scale that exposes the potential role of both α and β solvent fluctuations in modulating protein dynamics. The results open the possibility of probing hydration level phenomena in this system using a combination of NMR and optical probes.

  9. Anisotropic reversed micelles with fluorocarbon-hydrocarbon hybrid surfactants in supercritical CO2.

    Science.gov (United States)

    Sagisaka, Masanobu; Ono, Shinji; James, Craig; Yoshizawa, Atsushi; Mohamed, Azmi; Guittard, Frédéric; Enick, Robert M; Rogers, Sarah E; Czajka, Adam; Hill, Christopher; Eastoe, Julian

    2017-12-15

    Previous work (M. Sagisaka, et al. Langmuir 31 (2015) 7479-7487), showed the most effective fluorocarbon (FC) and hydrocarbon (HC) chain lengths in the hybrid surfactants FCm-HCn (sodium 1-oxo-1-[4-(perfluoroalkyl)phenyl]alkane-2-sulfonates, where m = FC length and n = HC length) were m and n = 6 and 4 for water solubilization, whereas m 6 and n 6, or m 6 and n 5, were optimal chain lengths for reversed micelle elongation in supercritical CO 2 . To clarify why this difference of only a few methylene chain units is so effective at tuning the solubilizing power and reversed micelle morphology, nanostructures of water-in-CO 2 (W/CO 2 ) microemulsions were investigated by high-pressure small-angle neutron scattering (SANS) measurements at different water-to-surfactant molar ratios (W 0 ) and surfactant concentrations. By modelling SANS profiles with cylindrical and ellipsoidal form factors, the FC6-HCn/W/CO 2 microemulsions were found to increase in size with increasing W 0 and surfactant concentration. Ellipsoidal cross-sectional radii of the FC6-HC4/W/CO 2 microemulsion droplets increased linearly with W 0 , and finally reached ∼39 Å and ∼78 Å at W 0  = 85 (close to the upper limit of solubilizing power). These systems appear to be the largest W/CO 2 microemulsion droplets ever reported. The aqueous domains of FC6-HC6 rod-like reversed micelles increased in size by 3.5 times on increasing surfactant concentration from 35 mM to 50 mM: at 35 mM, FC6-HC5 formed rod-like reversed micelles 5.3 times larger than FC6-HC6. Interestingly, these results suggest that hybrid HC-chains partition into the microemulsion aqueous cores with the sulfonate headgroups, or at the W/CO 2 interfaces, and so play important roles for tuning the W/CO 2 interfacial curvature. The super-efficient W/CO 2 -type solubilizer FC6-HC4, and the rod-like reversed micelle forming surfactant FC6-HC5, represent the most successful cases of low fluorine content additives

  10. Polymeric micelles as a diagnostic tool for image-guided drug delivery and radiotherapy of HER2 overexpressing breast cancer

    Science.gov (United States)

    Hoang, Nu Bryan

    Block copolymer micelles have emerged as a viable formulation strategy with several drugs relying on this technology in clinical evaluation. To date, information on the tumor penetration and intratumoral distribution of block copolymer micelles (BCM) has been quite limited. Thus, there is impetus to develop a radiolabeled formulation that can be used to gain invaluable insight into the intratumoral distribution of the BCMs. This information could then be used to direct formulation strategies as a means to optimize treatment outcomes. This thesis describes the synthesis and characterization of a targeted block copolymer micelle system based on poly(ethylene glycol)-block -poly(epsilon-caprolactone) labeled with the radionuclide Indium-111 (111In). The incorporation of the imageable component, 111In permits pursuit of image-guided drug delivery for real-time monitoring of tumor localization and intratumoral distribution. Intracellular trafficking of drugs and therapies such as Auger electron emitting radionuclides to perinuclear and nuclear regions of cells is critical to realizing their full therapeutic potential. HER2 specific antibodies (trastuzumab fab fragments) and nuclear localization signal peptides were conjugated to the surface of the BCMs to direct uptake in HER2 expressing cells and subsequent localization in the cell nucleus. Cell uptake was HER2 density dependent, confirming receptor-mediated internalization of the BCMs. Importantly, conjugation of NLS resulted in a significant increase in nuclear uptake of the radionuclide 111In. Successful nuclear targeting was shown to improve the antiproliferative effect of the Auger electrons. In addition, a significant radiation enhancement effect was observed by concurrent delivery of low-dose MTX and 111In in all breast cancer cell lines evaluated. Imaging enabled the accurate quantification of the specific tumor uptake of the micelles and visualization of their degree of tumor penetration in relation to

  11. 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.

  12. Probing interaction of charged nanoparticles with uncharged micelles

    Science.gov (United States)

    Kumar, Sugam; Aswal, V. K.; Kohlbrecher, J.

    2013-02-01

    Small-angle neutron scattering (SANS) and dynamic light scattering (DLS) studies have been carried out to study interaction of anionic nanoparticles with uncharged (non-ionic) C12E10 micelles. DLS results show increase in the effective size of nanoparticles on addition of C12E10. Contrast variation SANS confirms the micelles decoration of nanoparticles which is believed to be driven by the hydrogen bonding between them. The number of adsorbed micelles per nanoparticle increases with the increase in the nanoparticle size. Surface number density is also found to be increasing with increase in particle size indicating favored adsorption for larger curvature.

  13. Depletion interaction of casein micelles and an exocellular polysaccharide

    Science.gov (United States)

    Tuinier, R.; Ten Grotenhuis, E.; Holt, C.; Timmins, P. A.; de Kruif, C. G.

    1999-07-01

    Casein micelles become mutually attractive when an exocellular polysaccharide produced by Lactococcus lactis subsp. cremoris NIZO B40 (hereafter called EPS) is added to skim milk. The attraction can be explained as a depletion interaction between the casein micelles induced by the nonadsorbing EPS. We used three scattering techniques (small-angle neutron scattering, turbidity measurements, and dynamic light scattering) to measure the attraction. In order to connect the theory of depletion interaction with experiment, we calculated structure factors of hard spheres interacting by a depletion pair potential. Theoretical predictions and all the experiments showed that casein micelles became more attractive upon increasing the EPS concentration.

  14. Logarithmic Exchange Kinetics in Monodisperse Copolymeric Micelles

    Science.gov (United States)

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

    2017-06-01

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

  15. 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

  16. 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.

  17. Micelles driven magnetite (Fe3O4) hollow spheres and a study on AC magnetic properties for hyperthermia application

    International Nuclear Information System (INIS)

    Goswami, Madhuri Mandal; Dey, Chaitali; Bandyopadhyay, Ayan; Sarkar, Debasish; Ahir, Manisha

    2016-01-01

    Here we have discussed about designing the magnetic particles for hyperthermia therapy and done some studies in this direction. We have used oleylamine micelles as template to synthesize hollow–nanospheres (HNS) of magnetite by solvo-thermal technique. We have shown that oleylamine plays an important role to generate hollow particles. Structural analysis was done by XRD measurement and morphological measurements like SEM and TEM was performed to confirm the shape and size of hollow sphere particles. The detail magnetic measurements give an idea about the application of these HNS for magnetic heating in hyperthermia therapy. In vitro cytotoxicity studies reveal that tolerable dose rate for these particles can be significantly high and particles are non-toxic in nature. Being hollow in structure and magnetic in nature such materials will also be useful in other application fields like in drug delivery, drug release, arsenic and heavy metal removal by adsorption technique, magnetic separation etc. - Graphical abstract: Oleylamine micelles driven easy synthesis of hollow nanosphere (HNS) magnetite for hyperthermia therapy. - Highlights: • We have reported a new method of synthesis of hollow spheres of magnetite using micelles as model core and removal of micelles evolve the hollow like structure by relocating the core particles to the edge one. • Size can be controlled by varying the micellar concentration. • The detail magnetic measurements give an idea of applicability of these nano hollow spheres (NHS) in hyperthermia therapy. • Cyto-toxicity study reveals that these particles are highly biofriendly and dose rate can be increased upto a significant amount.

  18. Structure and reactivity in amphiphile-water micelles

    International Nuclear Information System (INIS)

    Chevalier, Yves

    1985-01-01

    Following a review of the general properties of micelles, this report contains two parts: - A structural study of octylphosphate micelles. Important structural changes have been evidenced by mean of small angle neutron scattering as the electrical charge of the interface is varied. The NMR relaxation study of the conformation of the hydrocarbon chains has shown that the micellar core is disordered in contrast with the interface which is rather structured. The diffusion motions in the interface and the segmental motions of the chains are fast. - Studies on the reactivity in micelles have been carried out. A large micellar effect on the complexation of transition ions by amphiphilic ligands is evidenced. The problem of solute localization in micelles is developed with few examples. (author) [fr

  19. The essential component in DNA-based information storage system: robust error-tolerating module

    Directory of Open Access Journals (Sweden)

    Aldrin Kay-Yuen eYim

    2014-11-01

    Full Text Available The size of digital data is ever increasing and is expected to grow to 40,000EB by 2020, yet the estimated global information storage capacity in 2011 is less than 300EB, indicating that most of the data are transient. DNA, as a very stable nano-molecule, is an ideal massive storage device for long-term data archive. The two most notable illustrations are from Church et al. and Goldman et al., whose approaches are well-optimized for most sequencing platforms – short synthesized DNA fragments without homopolymer. Here we suggested improvements on error handling methodology that could enable the integration of DNA-based computational process, e.g. algorithms based on self-assembly of DNA. As a proof of concept, a picture of size 438 bytes was encoded to DNA with Low-Density Parity-Check error-correction code. We salvaged a significant portion of sequencing reads with mutations generated during DNA synthesis and sequencing and successfully reconstructed the entire picture. A modular-based programming framework - DNAcodec with a XML-based data format was also introduced. Our experiments demonstrated the practicability of long DNA message recovery with high error-tolerance, which opens the field to biocomputing and synthetic biology.

  20. The Essential Component in DNA-Based Information Storage System: Robust Error-Tolerating Module.

    Science.gov (United States)

    Yim, Aldrin Kay-Yuen; Yu, Allen Chi-Shing; Li, Jing-Woei; Wong, Ada In-Chun; Loo, Jacky F C; Chan, King Ming; Kong, S K; Yip, Kevin Y; Chan, Ting-Fung

    2014-01-01

    The size of digital data is ever increasing and is expected to grow to 40,000 EB by 2020, yet the estimated global information storage capacity in 2011 is <300 EB, indicating that most of the data are transient. DNA, as a very stable nano-molecule, is an ideal massive storage device for long-term data archive. The two most notable illustrations are from Church et al. and Goldman et al., whose approaches are well-optimized for most sequencing platforms - short synthesized DNA fragments without homopolymer. Here, we suggested improvements on error handling methodology that could enable the integration of DNA-based computational process, e.g., algorithms based on self-assembly of DNA. As a proof of concept, a picture of size 438 bytes was encoded to DNA with low-density parity-check error-correction code. We salvaged a significant portion of sequencing reads with mutations generated during DNA synthesis and sequencing and successfully reconstructed the entire picture. A modular-based programing framework - DNAcodec with an eXtensible Markup Language-based data format was also introduced. Our experiments demonstrated the practicability of long DNA message recovery with high error tolerance, which opens the field to biocomputing and synthetic biology.

  1. Slow elimination of injured liver DNA bases of γ-irradiated old mice

    International Nuclear Information System (INIS)

    Gaziev, A.I.; Malakhov, L.V.; Fomenko, L.A.

    1982-01-01

    The paper presents a study of the elimination of injured bases from the liver DNA of old and young mice after their exposure to γ rays. The presented data show that if DNA from the liver of irradiated mice is treated with incision enzymes, its priming activity is increased. In the case of enzymatic treatment of DNA isolated 5 h after irradiation we find a great difference between the priming activity of the liver DNA of old and young mice. The reason for this difference is that the liver DNA of 20-month old mice 5 h after irradiation still has many unrepaired injured bases. These data indicated that the rate of incision of γ-injured DNA bases in the liver of old mice is lower than in the liver of young mice. In the liver of mice of different age the rate of restitution of DNA, single-strand breaks induced by γ rays in doses up to 100 Gy is the same. At the same time, the level of induced reparative synthesis of DNA in cells of an old organism is lower than in cells of a young organism. The obtained data suggest that reduction of the rate of elimination of modified bases from the cell DNA of 20-month old mice is due to reduction of the activity of the DNA repair enzymes or to restrictions in the chromatin in the access of these enzymes to the injured regions of DNA in the cells of old animals

  2. A neutron scattering study of triblock copolymer micelles

    International Nuclear Information System (INIS)

    Gerstenberg, M.C.

    1997-11-01

    The thesis describes the neutron scattering experiments performed on poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymer micelles in aqueous solution. The studies concern the non-ionic triblock copolymer P85 which consists of two outer segments of 25 monomers of ethylene oxide attached to a central part of 40 monomers of propylene oxide. The amphiphilic character of P85 leads to formation of various structures in aqueous solution such as spherical micelles, rod-like structures, and a BCC liquid-crystal mesophase of spherical micelles. The present investigations are centered around the micellar structures. In the first part of this thesis a model for the micelle is developed for which an analytical scattering form factor can be calculated. The micelle is modeled as a solid sphere with tethered Gaussian chains. Good agreement was found between small-angle neutron scattering experiments and the form factor of the spherical P85 micelles. Above 60 deg. C some discrepancies were found between the model and the data which is possibly due to an elongation of the micelles. The second part focuses on the surface-induced ordering of the various micellar aggregates in the P85 concentration-temperature phase diagram. In the spherical micellar phase, neutron reflection measurements indicated a micellar ordering at the hydrophilic surface of quartz. Extensive modeling was performed based on a hard sphere description of the micellar interaction. By convolution of the distribution of hard spheres at a hard wall, obtained from Monte Carlo simulations, and the projected scattering length density of the micelle, a numerical expression was obtained which made it possible to fit the data. The hard-sphere-hard-wall model gave an excellent agreement in the bulk micellar phase. However, for higher concentrations (25 wt % P85) close to the transition from the micellar liquid into a micellar cubic phase, a discrepancy was found between the model and the

  3. 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

  4. Polymeric micelles for potentiated antiulcer and anticancer activities of naringin

    Science.gov (United States)

    Mohamed, Elham Abdelmonem; Abu Hashim, Irhan Ibrahim; Yusif, Rehab Mohammad; Shaaban, Ahmed Abdel Aziz; El-Sheakh, Ahmed Ramadan; Hamed, Mohammed Fawzy; Badria, Farid Abd Elreheem

    2018-01-01

    Naringin is one of the most interesting phytopharmaceuticals that has been widely investigated for various biological actions. Yet, its low water solubility, limited permeability, and suboptimal bioavailability limited its use. Therefore, in this study, polymeric micelles of naringin based on pluronic F68 (PF68) were developed, fully characterized, and optimized. The optimized formula was investigated regarding in vitro release, storage stability, and in vitro cytotoxicity vs different cell lines. Also, cytoprotection against ethanol-induced ulcer in rats and antitumor activity against Ehrlich ascites carcinoma in mice were investigated. Nanoscopic and nearly spherical 1:50 micelles with the mean diameter of 74.80±6.56 nm and narrow size distribution were obtained. These micelles showed the highest entrapment efficiency (EE%; 96.14±2.29). The micelles exhibited prolonged release up to 48 vs 10 h for free naringin. The stability of micelles was confirmed by insignificant changes in drug entrapment, particle size, and retention (%) (91.99±3.24). At lower dose than free naringin, effective cytoprotection of 1:50 micelles against ethanol-induced ulcer in rat model has been indicated by significant reduction in mucosal damage, gastric level of malondialdehyde, gastric expression of tumor necrosis factor-alpha, caspase-3, nuclear factor kappa-light-chain-enhancer of activated B cells, and interleukin-6 with the elevation of gastric reduced glutathione and superoxide dismutase when compared with the positive control group. As well, these micelles provoked pronounced antitumor activity assessed by potentiated in vitro cytotoxicity particularly against colorectal carcinoma cells and tumor growth inhibition when compared with free naringin. In conclusion, 1:50 naringin–PF68 micelles can be represented as a potential stable nanodrug delivery system with prolonged release and enhanced antiulcer as well as antitumor activities. PMID:29497294

  5. Treating acute cystitis with biodegradable micelle-encapsulated quercetin

    Directory of Open Access Journals (Sweden)

    Wang BL

    2012-05-01

    Full Text Available Bi Lan Wang1, Xiang Gao1,2, Ke Men1, Jinfeng Qiu1, Bowen Yang3, Ma Ling Gou1, Mei Juan Huang1, Ning Huang2, Zhi Yong Qian1, Xia Zhao1, Yu Quan Wei11State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, 2Department of Pathophysiology, College of Preclinical and Forensic Medical Sciences, 3College of Life Science, Sichuan University, Chengdu, People’s Republic of ChinaAbstract: Intravesical application of an anti-inflammatory drug is an efficient strategy for acute cystitis therapy. Quercetin (QU is a potent anti-inflammatory agent; however, its poor water solubility restricts its clinical application. In an attempt to improve water solubility of QU, biodegradable monomethoxy poly(ethylene glycol-poly(ε-caprolactone (MPEG-PCL micelles were used to encapsulate QU by self-assembly methods, creating QU/MPEG-PCL micelles. These QU/MPEG-PCL micelles with DL of 7% had a mean particle size of ~34 nm, and could release QU for an extended period in vitro. The in vivo study indicated that intravesical application of MPEG-PCL micelles did not induce any toxicity to the bladder, and could efficiently deliver cargo to the bladder. Moreover, the therapeutic efficiency of intravesical administration of QU/MPEG-PCL micelles on acute cystitis was evaluated in vivo. Results indicated that QU/MPEG-PCL micelle treatment efficiently reduced the edema and inflammatory cell infiltration of the bladder in an Escherichia coli-induced acute cystitis model. These data suggested that MPEG-PCL micelle was a candidate intravesical drug carrier, and QU/MPEG-PCL micelles may have potential application in acute cystitis therapy.Keywords: nanomedicine, MPEG-PCL, self-assembly

  6. 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

  7. DNA based random key generation and management for OTP encryption.

    Science.gov (United States)

    Zhang, Yunpeng; Liu, Xin; Sun, Manhui

    2017-09-01

    One-time pad (OTP) is a principle of key generation applied to the stream ciphering method which offers total privacy. The OTP encryption scheme has proved to be unbreakable in theory, but difficult to realize in practical applications. Because OTP encryption specially requires the absolute randomness of the key, its development has suffered from dense constraints. DNA cryptography is a new and promising technology in the field of information security. DNA chromosomes storing capabilities can be used as one-time pad structures with pseudo-random number generation and indexing in order to encrypt the plaintext messages. In this paper, we present a feasible solution to the OTP symmetric key generation and transmission problem with DNA at the molecular level. Through recombinant DNA technology, by using only sender-receiver known restriction enzymes to combine the secure key represented by DNA sequence and the T vector, we generate the DNA bio-hiding secure key and then place the recombinant plasmid in implanted bacteria for secure key transmission. The designed bio experiments and simulation results show that the security of the transmission of the key is further improved and the environmental requirements of key transmission are reduced. Analysis has demonstrated that the proposed DNA-based random key generation and management solutions are marked by high security and usability. Published by Elsevier B.V.

  8. 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.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  10. DNA-based species detection capabilities using laser transmission spectroscopy.

    Science.gov (United States)

    Mahon, A R; Barnes, M A; Li, F; Egan, S P; Tanner, C E; Ruggiero, S T; Feder, J L; Lodge, D M

    2013-01-06

    Early detection of invasive species is critical for effective biocontrol to mitigate potential ecological and economic damage. Laser transmission spectroscopy (LTS) is a powerful solution offering real-time, DNA-based species detection in the field. LTS can measure the size, shape and number of nanoparticles in a solution and was used here to detect size shifts resulting from hybridization of the polymerase chain reaction product to nanoparticles functionalized with species-specific oligonucleotide probes or with the species-specific oligonucleotide probes alone. We carried out a series of DNA detection experiments using the invasive freshwater quagga mussel (Dreissena bugensis) to evaluate the capability of the LTS platform for invasive species detection. Specifically, we tested LTS sensitivity to (i) DNA concentrations of a single target species, (ii) the presence of a target species within a mixed sample of other closely related species, (iii) species-specific functionalized nanoparticles versus species-specific oligonucleotide probes alone, and (iv) amplified DNA fragments versus unamplified genomic DNA. We demonstrate that LTS is a highly sensitive technique for rapid target species detection, with detection limits in the picomolar range, capable of successful identification in multispecies samples containing target and non-target species DNA. These results indicate that the LTS DNA detection platform will be useful for field application of target species. Additionally, we find that LTS detection is effective with species-specific oligonucleotide tags alone or when they are attached to polystyrene nanobeads and with both amplified and unamplified DNA, indicating that the technique may also have versatility for broader applications.

  11. Probing the nature of hydrogen bonds in DNA base pairs.

    Science.gov (United States)

    Mo, Yirong

    2006-07-01

    Energy decomposition analyses based on the block-localized wave-function (BLW-ED) method are conducted to explore the nature of the hydrogen bonds in DNA base pairs in terms of deformation, Heitler-London, polarization, electron-transfer and dispersion-energy terms, where the Heitler-London energy term is composed of electrostatic and Pauli-exchange interactions. A modest electron-transfer effect is found in the Watson-Crick adenine-thymine (AT), guanine-cytosine (GC) and Hoogsteen adenine-thymine (H-AT) pairs, confirming the weak covalence in the hydrogen bonds. The electrostatic attraction and polarization effects account for most of the binding energies, particularly in the GC pair. Both theoretical and experimental data show that the GC pair has a binding energy (-25.4 kcal mol(-1) at the MP2/6-31G** level) twice that of the AT (-12.4 kcal mol(-1)) and H-AT (-12.8 kcal mol(-1)) pairs, compared with three conventional N-H...O(N) hydrogen bonds in the GC pair and two in the AT or H-AT pair. Although the remarkably strong binding between the guanine and cytosine bases benefits from the opposite orientations of the dipole moments in these two bases assisted by the pi-electron delocalization from the amine groups to the carbonyl groups, model calculations demonstrate that pi-resonance has very limited influence on the covalence of the hydrogen bonds. Thus, the often adopted terminology "resonance-assisted hydrogen bonding (RHAB)" may be replaced with "resonance-assisted binding" which highlights the electrostatic rather than electron-transfer nature of the enhanced stabilization, as hydrogen bonds are usually regarded as weak covalent bonds.

  12. 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...

  13. Basic investigations on LCV micelle gel

    Science.gov (United States)

    Ebenezer, S. B.; Rafic, M. K.; Ravindran, P. B.

    2013-06-01

    The aim of this study was to investigate the feasibility of using Leuco Crystal Violet (LCV) based micelle gel dosimeter as a quality assurance tool in radiotherapy applications. Basic properties such as absorption coefficient and diffusion of LCV gel phantom over time were evaluated. The gel formulation consisted of 25 mM Trichloroacetic acid, 1mM LCV, 4 mM Triton X-100, 4% gelatin by mass and distilled water. The advantages of using this gel are its tissue equivalence, easy and less preparation time, lower diffusion rate and it can be read with an optical scanner. We were able to reproduce some of the results of Babic et al. The peak absorption was found to be at 600 nm and hence a matrix of yellow LEDs was used as light source. The profiles obtained from projection images confirmed the diffusion of LCV gel after 6 hours of irradiation. Hence the LCV gel phantom should be read before 6 hours post irradiation to get accurate dose information as suggested previously.

  14. Protein separation using affinity-based reversed micelles

    Science.gov (United States)

    Sun; Gu; Tong; Bai; Ichikawa; Furusaki

    1999-05-01

    Reversed micellar two-phase extraction is a developing technique for protein separation. Introduction of an affinity ligand is considered to be an effective approach to increase the selectivity and capacity of reversed micelles. In this article, Cibacron Blue F3G-A (CB) as an affinity ligand was immobilized to reversed micelles composed of soybean lecithin by a two-phase reaction. The affinity partitioning of lysozyme and bovine serum albumin (BSA) to the CB-lecithin micelles was studied. Formation of mixed micelles by additionally introducing a nonionic surfactant, Tween 85, to the CB-lecithin micelles was effective to increase the solubilization of lysozyme due to the increase of W0 (water/surfactant molar ratio)/micellar size. The partitioning isotherms of lysozyme to the CB-lecithin micelles with and without Tween 85 were expressed by the Langmuir equation. The dissociation constants in the Langmuir equation decreased on addition of Tween 85, indicating the increase of the effectiveness of lysozyme binding to the immobilized CB. On addition of 20 g/L Tween 85 to 50 g/L lecithin/hexane micellar phase containing 0.1 mmol/L CB, the extraction capacity for lysozyme could be increased by 42%. Moreover, the CB-lecithin micelles with or without Tween 85 showed significant size exclusion for BSA due to its high molecular weight. Thus, lysozyme and BSA were separated from artificial solutions containing the two proteins. In addition, the affinity-based reversed micellar phase containing Tween 85 was recycled three times for lysozyme purification from crude egg-white solutions. Lysozyme purity increased by 16-18-fold, reaching 60-70% in the recycled use.

  15. Core-Shell Nanocatalysts Obtained in Reverse Micelles: Structural and Kinetic Aspects

    Directory of Open Access Journals (Sweden)

    Concha Tojo

    2015-01-01

    Full Text Available Ability to control the metal arrangement in bimetallic nanocatalysts is the key to improving their catalytic activity. To investigate how metal distribution in nanostructures can be modified, we developed a computer simulation model on the synthesis of bimetallic nanoparticles obtained in microemulsions by a one-pot method. The calculations allow predicting the metal arrangement in nanoparticle under different experimental conditions. We present results for two couples of metals, Au/Pt (Δε=0.26 V and Au/Ag (Δε=0.19 V, but conclusions can be generalized to other bimetallic pairs with similar difference in standard reduction potentials. It was proved that both surface and interior compositions can be controlled at nanometer resolution easily by changing the initial reactant concentration inside micelles. Kinetic analysis demonstrates that the confinement of reactants inside micelles has a strong effect on the reaction rates of the metal precursors. As a result, the final nanocatalyst shows a more mixed core and a better defined shell as concentration is higher.

  16. PEE-PEO block copolymer exchange rate between micelles is detergent and temperature activated

    Science.gov (United States)

    Schantz, Allen; Saboe, Patrick; Lee, Hee-Young; Sines, Ian; Butler, Paul; Bishop, Kyle; Maranas, Janna; Kumar, Manish

    We examine the kinetics of polymer chain exchange between polymer/detergent micelles, a system relevant to the synthesis of protein-containing biomimetic membranes. Although chain exchange between polymer aggregates in water is too slow to observe, adding detergent allows us to determine chain exchange rates using time-resolved small-angle neutron scattering (TR-SANS). We examine a membrane-protein-relevant, vesicle-forming ultra-short polymer, Poly(ethyl ethylene)20-Poly(ethylene oxide)18 (PEE20-PEO18). PEE20-PEO18 is solubilized in mixed micelles with the membrane-protein-compatible non-ionic detergent octyl- β -D-glucoside (OG). We show that OG activates block copolymer exchange, and obtain rate constants at two detergent concentrations above the CMC (critical micellar concentration) of OG. We find that chain exchange increases two orders of magnitude when temperature increases from 308 to 338 K, and that even a 1 mg/mL increase in OG concentration leads to a noticeable increase in exchange rate. We also calculate the activation energy for chain exchange and find that it is much higher than for lipid exchange. These findings explain the need for high detergent concentration and/or temperature to synthesize densely packed polymer/protein membranes.

  17. Charge transport by inverse micelles in non-polar media

    Science.gov (United States)

    Strubbe, Filip; Neyts, Kristiaan

    2017-11-01

    Charged inverse micelles play an important role in the electrical charging and the electrodynamics of nonpolar colloidal dispersions relevant for applications such as electronic ink displays and liquid toner printing. This review examines the properties and the behavior of charged inverse micelles in microscale devices in the absence of colloidal particles. It is discussed how charge in nonpolar liquids is stabilized in inverse micelles and how conductivity depends on the inverse micelle size, water content and ionic impurities. Frequently used nonpolar surfactant systems are investigated with emphasis on aerosol-OT (AOT) and poly-isobutylene succinimide (PIBS) in dodecane. Charge generation in the bulk by disproportionation is studied from measurements of conductivity as a function of surfactant concentration and from generation currents in quasi steady-state. When a potential difference is applied, the steady-state situation can show electric field screening or complete charge separation. Different regimes of charge transport are identified when a voltage step is applied. It is shown how the transient and steady-state currents depend on the rate of bulk generation, on insulating layers and on the sticking or non-sticking behavior of charged inverse micelles at interfaces. For the cases of AOT and PIBS in dodecane, the magnitude of the generation rate and the type of interaction at the interface are very different.

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

    Science.gov (United States)

    Tabakovic, Amra

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

  19. Stable and biocompatible genipin-inducing interlayer-crosslinked micelles for sustained drug release

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Yu; Zhang, Xiaojin, E-mail: zhangxj@cug.edu.cn [China University of Geosciences, Faculty of Materials Science and Chemistry (China)

    2017-05-15

    To develop the sustained drug release system, here we describe genipin-inducing interlayer-crosslinked micelles crosslinked via Schiff bases between the amines of amphiphilic linear-hyperbranched polymer poly(ethylene glycol)-branched polyethylenimine-poly(ε-caprolactone) (PEG-PEI-PCL) and genipin. The generation of Schiff bases was confirmed by the color changes and UV-Vis absorption spectra of polymeric micelles after adding genipin. The particle size, morphology, stability, in vitro cytotoxicity, drug loading capacity, and in vitro drug release behavior of crosslinked micelles as well as non-crosslinked micelles were characterized. The results indicated that genipin-inducing interlayer-crosslinked micelles had better stability and biocompatibility than non-crosslinked micelles and glutaraldehyde-inducing interlayer-crosslinked micelles. In addition, genipin-inducing interlayer-crosslinked micelles were able to improve drug loading capacity, reduce the initial burst release, and achieve sustained drug release.

  20. 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

  1. Enhanced cytotoxicity of TATp-bearing paclitaxel-loaded micelles in vitro and in vivo

    OpenAIRE

    Sawant, Rupa R.; Torchilin, Vladimir P.

    2009-01-01

    Cell-penetrating peptide (TATp) was attached to the distal tips of polyethylene glycol (PEG) moieties of polyethyleneglycol-phosphatidylethanolamine (PEG-PE) micelles loaded with paclitaxel (PCT). The TATp-modified micelles demonstrated an increased interaction with cancer cells compared to non-modified micelles resulting in a significant increase of the in vitro cytotoxicity to different cancer cells. TATp-modified PCT-loaded micelles were administered intratumorally in mice and the inductio...

  2. Determination of the aggregation number for micelles by isothermal titration calorimetry

    DEFF Research Database (Denmark)

    Olesen, Niels Erik; Holm, Rene; Westh, Peter

    2014-01-01

    Isothermal titration calorimetry (ITC) has previously been applied to estimate the aggregation number (n), Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) of micellization. However, some difficulties of micelle characterization by ITC still remain; most micelles have aggregation numbers...... insight into optimal design of titration protocols for micelle characterization. By applying the new method, the aggregation number of sodium dodecyl sulphate and glycochenodeoxycholate was determined at concentrations around their critical micelle concentration (CMC)...

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    Kilikian B. V.

    2000-01-01

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

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

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  6. 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.

  7. 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.

  8. Enhanced conjugation of Candida rugosa lipase onto multiwalled carbon nanotubes using reverse micelles as attachment medium and application in nonaqueous biocatalysis.

    Science.gov (United States)

    Raghavendra, Tripti; Vahora, Uzma; Shah, Amita R; Madamwar, Datta

    2014-01-01

    Three liquid phases (viz. aqueous, nonaqueous, and reverse micelles) were scrutinized as medium for attachment of the enzyme Candida rugosa lipase (CRL) onto multiwalled carbon nanotubes (CNTs). The nanotubes were functionalized to attain carboxyl and amino groups on their surfaces before enzyme conjugation. Transmission electron microscopy and Fourier transformation infrared spectroscopic studies were used for characterization of the nanotubes during the course of functionalization. High enzyme loadings associated with the functionalized CNTs were observed when reverse micelles were used as the attachment medium. In addition, high activity in terms of ester synthesis in organic solvents was also observed while using those preparations. The nanobioconjugates prepared using reverse micelles were found to be highly sturdy and exhibited appreciable operational stability of around 95 ± 3% at 20th cycle (in case of carboxylated nanotubes) and 90 ± 5% at 10th cycle (in case of aminated nanotubes) for esterification. This shows the potential application of reverse micelles as the attachment medium for surface active enzymes such as CRL onto CNTs. © 2014 American Institute of Chemical Engineers.

  9. Proton transfer in ionic and neutral reverse micelles.

    Science.gov (United States)

    Lawler, Christian; Fayer, Michael D

    2015-05-14

    Proton-transfer kinetics in both ionic and neutral reverse micelles were studied by time-correlated single-photon counting investigations of the fluorescent photoacid 8-hydroxypyrene-1,3,6-trisulfonate (HPTS). Orientational dynamics of dissolved probe molecules in the water pools of the reverse micelles were also investigated by time-dependent fluorescence anisotropy measurements of MPTS, the methoxy derivative of HPTS. These experiments were compared to the same experiments in bulk water. It was found that in ionic reverse micelles (surfactant Aerosol OT, AOT), orientational motion (fluorescence anisotropy decay) of MPTS was relatively unhindered, consistent with MPTS being located in the water core of the reverse micelle away from the water-surfactant interface. In nonionic reverse micelles (surfactant Igepal CO-520, Igepal), however, orientational anisotropy displayed a slow multiexponential decay consistent with wobbling-in-a-cone behavior, indicating MPTS is located at the water-surfactant interface. HPTS proton transfer in ionic reverse micelles followed kinetics qualitatively like those in bulk water, albeit slower, with the long-time power law time dependence associated with recombination of the proton with the dissociated photoacid, suggesting a modified diffusion-controlled process. However, the power law exponents in the ionic reverse micelles are smaller (∼ -0.55) than that in bulk water (-1.1). In neutral reverse micelles, proton-transfer kinetics did not show discernible power law behavior and were best represented by a two-component model with one relatively waterlike population and a population with a faster fluorescence lifetime and negligible proton transfer. We explain the Igepal results on the basis of close association between the probe and the neutral water-surfactant interface, with the probe experiencing a distribution of more and less waterlike environments. In addition, the observation in bulk water of a power law t(-1.1) for diffusion

  10. The Critical Micelle Concentration of Asphaltenes as Measured by Calorimetry

    DEFF Research Database (Denmark)

    Andersen, Simon Ivar; Christensen, S. D.

    2000-01-01

    Micellization of asphaltenes in solution has been investigated using a micro calorimetric titration procedure (Andersen, S. I.; Birdi, K. S. J Colloid Interface Sci. 1991, 142, 497). The method uses the analysis of heat of dissociation and dilution of asphaltene micelles when a pure solvent (or...... solvent mixture) is titrated with a solution of asphaltene in the same solvent. The asphaltene concentration of the injected solution is at a level above the critical micelle concentration (CMC). In the present paper the procedure is applied in investigation of asphaltenes as well as subfractions...

  11. From molecules to management: adopting DNA-based methods for monitoring biological invasions in aquatic environments

    Science.gov (United States)

    Recent technological advances have driven rapid development of DNA-based methods designed to facilitate detection and monitoring of invasive species in aquatic environments. These tools promise to significantly alleviate difficulties associated with traditional monitoring approac...

  12. Binding of chloroquine to ionic micelles: Effect of pH and micellar surface charge

    Energy Technology Data Exchange (ETDEWEB)

    Souza Santos, Marcela de, E-mail: marcelafarmausp77@gmail.com [Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Avenida do Café, s/n, Ribeirão Preto, São Paulo 14040-903 (Brazil); Perpétua Freire de Morais Del Lama, Maria, E-mail: mpemdel@fcfrp.usp.br [Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Avenida do Café, s/n, Ribeirão Preto, São Paulo 14040-903 (Brazil); Instituto Nacional de Ciência e Tecnologia de Bioanalítica, Departamento de Química Analítica, Universidade Estadual de Campinas, Cidade Universitária Zeferino Vaz, s/n, Campinas, São Paulo 13083-970 (Brazil); Siuiti Ito, Amando, E-mail: amandosi@ffclrp.usp.br [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes, 3900, Ribeirão Preto, São Paulo 14040-901 (Brazil); and others

    2014-03-15

    The pharmacological action of chloroquine relies on its ability to cross biological membranes in order to accumulate inside lysosomes. The present work aimed at understanding the basis for the interaction between different chloroquine species and ionic micelles of opposite charges, the latter used as a simple membrane model. The sensitivity of absorbance and fluorescence of chloroquine to changes in its local environment was used to probe its interaction with cetyltrimethylammonium micelles presenting bromide (CTAB) and sulfate (CTAS) as counterions, in addition to dodecyl sulfate micelles bearing sodium (SDS) and tetramethylammonium (TMADS) counterions. Counterion exchange was shown to have little effect on drug–micelle interaction. Chloroquine first dissociation constant (pKa{sub 1}) shifted to opposite directions when anionic and cationic micelles were compared. Chloroquine binding constants (K{sub b}) revealed that electrostatic forces mediate charged drug–micelle association, whereas hydrophobic interactions allowed neutral chloroquine to associate with anionic and cationic micelles. Fluorescence quenching studies indicated that monoprotonated chloroquine is inserted deeper into the micelle surface of anionic micelles than its neutral form, the latter being less exposed to the aqueous phase when associated with cationic over anionic assemblies. The findings provide further evidence that chloroquine–micelle interaction is driven by a tight interplay between the drug form and the micellar surface charge, which can have a major effect on the drug biological activity. -- Highlights: • Chloroquine (CQ) pKa{sub 1} increased for SDS micelles and decreased for CTAB micelles. • CQ is solubilized to the surface of both CTAB and SDS micelles. • Monoprotonated CQ is buried deeper into SDS micelles than neutral CQ. • Neutral CQ is less exposed to aqueous phase in CTAB over SDS micelles. • Local pH and micellar surface charge mediate interaction of CQ with

  13. Amphiphilic block copolymer micelles with hydrophobically modified shells

    Czech Academy of Sciences Publication Activity Database

    Jelínek, K.; Uhlík, F.; Limpouchová, Z.; Matějíček, P.; Humpolíčková, J.; Procházka, K.; Tuzar, Zdeněk; Špírková, Milena; Hof, Martin

    2003-01-01

    Roč. 29, 10-11 (2003), s. 655-660 ISSN 0892-7022 R&D Projects: GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : micelles * conformation * NRET Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.721, year: 2003

  14. Ultrafast energy transfer in water-AOT reverse micelles

    NARCIS (Netherlands)

    Cringus, Dan; Bakulin, Artem; Lindner, Joerg; Voehringer, Peter; Pshenichnikov, Maxim S.; Wiersma, Douwe A.

    2007-01-01

    A spectroscopic investigation of the vibrational dynamics of water in a geometrically confined environment is presented. Reverse micelles of the ternary microemulsion H2O/AOT/n-octane (AOT = bis-2-ethylhexyl sulfosuccinate or aerosol-OT) with diameters ranging from 1 to 10 nm are used as a model

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

    Science.gov (United States)

    De Oliveira, Tiago; Guégan, Régis

    2016-09-20

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

  16. Solvent Effects on the Micelle - Influenced Aquation Reactions of ...

    African Journals Online (AJOL)

    The relative rates of the micelle-catalyzed/inhibited aquation reactions of the complexes: Fe(Ph2Phen), Fe(Me2Phen) and Fe(MePhen were investigated in ethylene glycol, water and aqueous acetone. The pseudo first oder rate constant, K vs (Triton X-100) profiles reveal that at all the (TX-100) concentration ranges ...

  17. 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.

  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. 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 las...

  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. Small angle neutron scattering studies of mixed micelles of sodium

    Indian Academy of Sciences (India)

    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 ...

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

    Science.gov (United States)

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

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

  3. 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

  4. DNA-polymer micelles as nanoparticles with recognition ability.

    Science.gov (United States)

    Talom, Renée Mayap; Fuks, Gad; Kaps, Leonard; Oberdisse, Julian; Cerclier, Christel; Gaillard, Cédric; Mingotaud, Christophe; Gauffre, Fabienne

    2011-11-25

    The Watson-Crick binding of DNA single strands is a powerful tool for the assembly of nanostructures. Our objective is to develop polymer nanoparticles equipped with DNA strands for surface-patterning applications, taking advantage of the DNA technology, in particular, recognition and reversibility. A hybrid DNA copolymer is synthesized through the conjugation of a ssDNA (22-mer) with a poly(ethylene oxide)-poly(caprolactone) diblock copolymer (PEO-b-PCl). It is shown that, in water, the PEO-b-PCl-ssDNA(22) polymer forms micelles with a PCl hydrophobic core and a hydrophilic corona made of PEO and DNA. The micelles are thoroughly characterized using electron microscopy (TEM and cryoTEM) and small-angle neutron scattering. The binding of these DNA micelles to a surface through DNA recognition is monitored using a quartz crystal microbalance and imaged by atomic force microscopy. The micelles can be released from the surface by a competitive displacement event. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Counterion condensation in ionic micelles as studied by a combined ...

    Indian Academy of Sciences (India)

    Abstract. 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 ...

  6. Micelle hydrogels for three-dimensional dose verification

    Science.gov (United States)

    Babic, S.; Battista, J.; Jordan, K.

    2009-05-01

    Gelatin hydrogels form a transparent and colourless matrix for polymerization or chromic reactions initiated by absorption of ionizing radiation. Generally, hydrogel chemistries have been limited to water soluble reactants. Work to adapt a water insoluble colourless leuco dye to coloured dye conversion reaction in hydrogels, led to the idea that micelles (i.e. tiny aggregates of surfactant molecules) may provide the necessary polar and nonpolar hybrid environment. Both leucomalachite green and leuco crystal violet radiochromic gels have been developed as three-dimensional (3-D) radiochromic dosimeters for optical computed tomography (CT) scanners. It has been found that the post-irradiation diffusion rates strongly correlate with the solubility of the leuco dyes. Since the crystal violet dye is more soluble in the micelle than in the surrounding water, the dose distribution degrades at the slower rate of micelle diffusion, thus yielding stable images of dose. A dosimetric characterization of leucomalachite green and leuco crystal violet gels, respectively, reveals that tissue equivalent micelle hydrogels are promising dosimeters for radiation therapy 3-D dose verification.

  7. Degradation patterns of tetracycline antibiotics in reverse micelles and water.

    Science.gov (United States)

    Sah, Hongkee

    2006-11-01

    The objective of this study was to determine the chemical stability of tetracycline and oxytetracycline hydro-chlorides in reverse micelles. Their reverse micellar solutions were prepared using cetyltrimethylammonium bromide, water and ethyl formate. The aqueous solutions of the tetracycline antibiotics were also prepared for comparison. The reverse micellar and aqueous solutions were stored at 37 degrees C. Samples were analyzed by high performance liquid chromatography. When evaluation was performed on an aqueous tetracycline HCl solution, its half-life was estimated to be 329 h. Its chemical stability was not improved after being dissolved in the reverse micelles, and a similar half-life of 330 h was observed. However, there were noticeable differences between the two systems in terms of degradation kinetics and degradation byproducts. On the other hand, oxytetracycline HCl was unstable in water so that its half-life was only 34 h. Very interestingly, pronounced improvement in stability was attained with the reverse micellar system: upon dissolving in the reverse micelles, its half-life was increased to 2402 h. There were also marked differences in degradation patterns and mechanisms of oxytetracycline HCl in water and the reverse micelles. Our study indicates that the reverse micellar system has potential applications in solubilizing and stabilizing oxytetracycline HCl, thereby contributing to the development of its dosage forms. Copyright (c) 2006 John Wiley & Sons, Ltd.

  8. 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

  9. Enhanced cytotoxicity of TATp-bearing paclitaxel-loaded micelles in vitro and in vivo.

    Science.gov (United States)

    Sawant, Rupa R; Torchilin, Vladimir P

    2009-06-05

    Cell-penetrating peptide (TATp) was attached to the distal tips of polyethyleneglycol (PEG) moieties of polyethyleneglycol-phosphatidylethanolamine (PEG-PE) micelles loaded with paclitaxel (PCT). The TATp-modified micelles demonstrated an increased interaction with cancer cells compared to non-modified micelles resulting in a significant increase of the in vitro cytotoxicity to different cancer cells. TATp-modified PCT-loaded micelles were administered intratumorally in mice and the induction of apoptosis in tumor cells was studied after 48h with the Terminal Deoxynucleotidyl Transferase Biotin-dUTP Nick End Labeling (TUNEL) assay using free PCT and TATp-free PCT-loaded PEG-PE micelles as controls. A significant apoptotic cell death was observed in tumors treated with PCT-loaded micelles modified with TATp, while the treatment with free PCT or with non-modified PCT-loaded micelles resulted in much smaller number of TUNEL-positive cells within tumors.

  10. 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

  11. Polysarcosine-Based Lipids: From Lipopolypeptoid Micelles to Stealth-Like Lipids in Langmuir Blodgett Monolayers

    Directory of Open Access Journals (Sweden)

    Benjamin Weber

    2016-12-01

    Full Text Available Amphiphiles and, in particular, PEGylated lipids or alkyl ethers represent an important class of non-ionic surfactants and have become key ingredients for long-circulating (“stealth” liposomes. While poly-(ethylene glycol (PEG can be considered the gold standard for stealth-like materials, it is known to be neither a bio-based nor biodegradable material. In contrast to PEG, polysarcosine (PSar is based on the endogenous amino acid sarcosine (N-methylated glycine, but has also demonstrated stealth-like properties in vitro, as well as in vivo. In this respect, we report on the synthesis and characterization of polysarcosine based lipids with C14 and C18 hydrocarbon chains and their end group functionalization. Size exclusion chromatography (SEC and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS analysis reveals that lipopeptoids with a degree of polymerization between 10 and 100, dispersity indices around 1.1, and the absence of detectable side products are directly accessible by nucleophilic ring opening polymerization (ROP. The values for the critical micelle concentration for these lipopolymers are between 27 and 1181 mg/L for the ones with C18 hydrocarbon chain or even higher for the C14 counterparts. The lipopolypeptoid based micelles have hydrodynamic diameters between 10 and 25 nm, in which the size scales with the length of the PSar block. In addition, C18PSar50 can be incorporated in 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC monolayers up to a polymer content of 3%. Cyclic compression and expansion of the monolayer showed no significant loss of polymer, indicating a stable monolayer. Therefore, lipopolypeptoids can not only be synthesized under living conditions, but my also provide a platform to substitute PEG-based lipopolymers as excipients and/or in lipid formulations.

  12. Synthesis by reverse microemulsion of nano structured ferrite to be utilized in hydrogen production by water

    International Nuclear Information System (INIS)

    Bellusci, M.; Annunziatini, C.; Alvani, C.; Colella, C.; La Barbera, A.; Padella, F.; Seralessandri, L.

    2005-10-01

    Micelle and reverse micelle microemulsions can be favourably utilized in producing nano sized particles. The paper reports a general description of microemulsions systems, as well as their application in materials synthesis. By using one of the described methods, nano structured manganese ferrite, to be utilized in hydrogen production. was synthesized and the produced material was characterized in terms of morphological, microstructure and thermal properties [it

  13. Micelles driven magnetite (Fe{sub 3}O{sub 4}) hollow spheres and a study on AC magnetic properties for hyperthermia application

    Energy Technology Data Exchange (ETDEWEB)

    Goswami, Madhuri Mandal, E-mail: madhuri@bose.res.in [Department of Condensed Matter Physics and Material Science, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106 (India); Dey, Chaitali [Department of Condensed Matter Physics and Material Science, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106 (India); CRNN, University of Calcutta, Block JD, Sector III, Salt Lake, Kolkata 700106 (India); Bandyopadhyay, Ayan [CRNN, University of Calcutta, Block JD, Sector III, Salt Lake, Kolkata 700106 (India); Sarkar, Debasish [Department of Condensed Matter Physics and Material Science, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106 (India); Ahir, Manisha [CRNN, University of Calcutta, Block JD, Sector III, Salt Lake, Kolkata 700106 (India)

    2016-11-01

    Here we have discussed about designing the magnetic particles for hyperthermia therapy and done some studies in this direction. We have used oleylamine micelles as template to synthesize hollow–nanospheres (HNS) of magnetite by solvo-thermal technique. We have shown that oleylamine plays an important role to generate hollow particles. Structural analysis was done by XRD measurement and morphological measurements like SEM and TEM was performed to confirm the shape and size of hollow sphere particles. The detail magnetic measurements give an idea about the application of these HNS for magnetic heating in hyperthermia therapy. In vitro cytotoxicity studies reveal that tolerable dose rate for these particles can be significantly high and particles are non-toxic in nature. Being hollow in structure and magnetic in nature such materials will also be useful in other application fields like in drug delivery, drug release, arsenic and heavy metal removal by adsorption technique, magnetic separation etc. - Graphical abstract: Oleylamine micelles driven easy synthesis of hollow nanosphere (HNS) magnetite for hyperthermia therapy. - Highlights: • We have reported a new method of synthesis of hollow spheres of magnetite using micelles as model core and removal of micelles evolve the hollow like structure by relocating the core particles to the edge one. • Size can be controlled by varying the micellar concentration. • The detail magnetic measurements give an idea of applicability of these nano hollow spheres (NHS) in hyperthermia therapy. • Cyto-toxicity study reveals that these particles are highly biofriendly and dose rate can be increased upto a significant amount.

  14. 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

  15. DNA bases assembled on the Au(110)/electrolyte interface: A combined experimental and theoretical study

    DEFF Research Database (Denmark)

    Salvatore, Princia; Nazmutdinov, Renat R.; Ulstrup, Jens

    2015-01-01

    , accompanied by a pair of strong voltammetry peaks in the double-layer region in acid solutions. Adsorption of the DNA bases gives featureless voltammograms with lower double-layer capacitance, suggesting that all the bases are chemisorbed on the Au(110) surface. Further investigation of the surface structures...... of the adlayers of the four DNA bases by EC-STM disclosed lifting of the Au(110) reconstruction, specific molecular packing in dense monolayers, and pH dependence of the A and G adsorption. DFT computations based on a cluster model for the Au(110) surface were performed to investigate the adsorption energy...... and geometry of the DNA bases in different adsorbate orientations. The optimized geometry is further used to compute models for STM images which are compared with the recorded STM images. This has provided insight into the physical nature of the adsorption. The specific orientations of A, C, G, and T on Au(110...

  16. Self-assembly of star micelle into vesicle in solvents of variable quality: the star micelle retains its core-shell nanostructure in the vesicle.

    Science.gov (United States)

    Liu, Nijuan; He, Qun; Bu, Weifeng

    2015-03-03

    Intra- and intermolecular interactions of star polymers in dilute solutions are of fundamental importance for both theoretical interest and hierarchical self-assembly into functional nanostructures. Here, star micelles with a polystyrene corona and a small ionic core bearing platinum(II) complexes have been regarded as a model of star polymers to mimic their intra- and interstar interactions and self-assembled behaviors in solvents of weakening quality. In the chloroform/methanol mixture solvents, the star micelles can self-assemble to form vesicles, in which the star micelles shrink significantly and are homogeneously distributed on the vesicle surface. Unlike the morphological evolution of conventional amphiphiles from micellar to vesicular, during which the amphiphilic molecules are commonly reorganized, the star micelles still retain their core-shell nanostructures in the vesicles and the coronal chains of the star micelle between the ionic cores are fully interpenetrated.

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

    DEFF Research Database (Denmark)

    Jensen, Andreas Tue Ingemann

    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...... 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......‐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 glycerolipid and a cholesteryl ether were synthesized with free primary alcohols and a series of their sulphonates (Ms, Ts, Tf) were...

  18. Characterization of nanoparticles based on block copolymer micelles

    Czech Academy of Sciences Publication Activity Database

    Pleštil, Josef; Pospíšil, Herman; Kříž, Jaroslav; Kadlec, Petr; Tuzar, Zdeněk; Cubitt, R.

    2001-01-01

    Roč. 17, č. 21 (2001), s. 6699-6704 ISSN 0743-7463 R&D Projects: GA AV ČR KSK4050111; GA ČR GA203/00/1317; GA ČR GA203/01/0536 Institutional research plan: CEZ:AV0Z4050913 Keywords : block copolymer micelles * nanoparticles * small - angle neutron scattering Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.963, year: 2001

  19. Internal dynamics in SDS micelles: neutron scattering study.

    Science.gov (United States)

    Sharma, V K; Mitra, S; Verma, G; Hassan, P A; Garcia Sakai, V; Mukhopadhyay, R

    2010-12-30

    The molecular dynamics of sodium dodecyl sulfate (SDS) micelle has been investigated using high-resolution incoherent quasielastic neutron scattering technique. Data analysis clearly shows presence of two distinct motions: whole micellar motion or global diffusion and faster internal motion of the SDS monomer. The global diffusion associated with the whole micelle is found to be Fickian in nature, and the corresponding diffusion coefficients are found to be consistent with those obtained from dynamic light scattering measurements. The internal motion is described with a model consistent with the structure of the micelle and which accounts for the flexibility of the chains. The SDS monomer consists of a head group, which lies on the surface of the globular micelle, and a tail that hangs from the head toward the center of the globule. Considering various factors like conformational changes of the SDS chains, bending, stretching of the chemical bonds, etc., the dynamics of the SDS molecules is successfully described by a model in which the hydrogen atoms undergo localized translational motion confined within spherical volumes. This volume increases linearly along the SDS chain such that the hydrogen atoms closer to the head group move within smaller spheres with lower diffusion constant than the hydrogen atoms away from the head group. This model is found to be consistent with the data over the whole temperature and concentration range. Diffusivity and the volume of the spheres are also found to increase with temperature. The effect of lowering the SDS concentration is found to be similar to that of increasing the temperature.

  20. Engineering single-polymer micelle shape using nonuniform spontaneous surface curvature

    Science.gov (United States)

    Moths, Brian; Witten, T. A.

    2018-03-01

    Conventional micelles, composed of simple amphiphiles, exhibit only a few standard morphologies, each characterized by its mean surface curvature set by the amphiphiles. Here we demonstrate a rational design scheme to construct micelles of more general shape from polymeric amphiphiles. We replace the many amphiphiles of a conventional micelle by a single flexible, linear, block copolymer chain containing two incompatible species arranged in multiple alternating segments. With suitable segment lengths, the chain exhibits a condensed spherical configuration in solution, similar to conventional micelles. Our design scheme posits that further shapes are attained by altering the segment lengths. As a first study of the power of this scheme, we demonstrate the capacity to produce long-lived micelles of horseshoe form using conventional bead-spring simulations in two dimensions. Modest changes in the segment lengths produce smooth changes in the micelle's shape and stability.

  1. Nanoparticle Contrast Agents for Computed Tomography: A Focus on Micelles

    Science.gov (United States)

    Cormode, David P.; Naha, Pratap C.; Fayad, Zahi A.

    2014-01-01

    Computed tomography (CT) is an X-ray based whole body imaging technique that is widely used in medicine. Clinically approved contrast agents for CT are iodinated small molecules or barium suspensions. Over the past seven years there has been a great increase in the development of nanoparticles as CT contrast agents. Nanoparticles have several advantages over small molecule CT contrast agents, such as long blood-pool residence times, and the potential for cell tracking and targeted imaging applications. Furthermore, there is a need for novel CT contrast agents, due to the growing population of renally impaired patients and patients hypersensitive to iodinated contrast. Micelles and lipoproteins, a micelle-related class of nanoparticle, have notably been adapted as CT contrast agents. In this review we discuss the principles of CT image formation and the generation of CT contrast. We discuss the progress in developing non-targeted, targeted and cell tracking nanoparticle CT contrast agents. We feature agents based on micelles and used in conjunction with spectral CT. The large contrast agent doses needed will necessitate careful toxicology studies prior to clinical translation. However, the field has seen tremendous advances in the past decade and we expect many more advances to come in the next decade. PMID:24470293

  2. Predicting proton titration in cationic micelle and bilayer environments

    Science.gov (United States)

    Morrow, Brian H.; Eike, David M.; Murch, Bruce P.; Koenig, Peter H.; Shen, Jana K.

    2014-08-01

    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 pKa'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 pKa 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 pKa 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.

  3. Uniform electroactive fibre-like micelle nanowires for organic electronics

    Science.gov (United States)

    Li, Xiaoyu; Wolanin, Piotr J.; Macfarlane, Liam R.; Harniman, Robert L.; Qian, Jieshu; Gould, Oliver E. C.; Dane, Thomas G.; Rudin, John; Cryan, Martin J.; Schmaltz, Thomas; Frauenrath, Holger; Winnik, Mitchell A.; Faul, Charl F. J.; Manners, Ian

    2017-06-01

    Micelles formed by the self-assembly of block copolymers in selective solvents have attracted widespread attention and have uses in a wide variety of fields, whereas applications based on their electronic properties are virtually unexplored. Herein we describe studies of solution-processable, low-dispersity, electroactive fibre-like micelles of controlled length from π-conjugated diblock copolymers containing a crystalline regioregular poly(3-hexylthiophene) core and a solubilizing, amorphous regiosymmetric poly(3-hexylthiophene) or polystyrene corona. Tunnelling atomic force microscopy measurements demonstrate that the individual fibres exhibit appreciable conductivity. The fibres were subsequently incorporated as the active layer in field-effect transistors. The resulting charge carrier mobility strongly depends on both the degree of polymerization of the core-forming block and the fibre length, and is independent of corona composition. The use of uniform, colloidally stable electroactive fibre-like micelles based on common π-conjugated block copolymers highlights their significant potential to provide fundamental insight into charge carrier processes in devices, and to enable future electronic applications.

  4. Extraction of DNA by the reverse micelle; Gyaku miseru ni yoru DNA no chushutsu

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Masahiro [Kyushu University, Fukuoka (Japan). Graduate School; Ono, Tsutomu; Horiuchi, Akihiko; Furusaki, Shintaro

    1999-03-05

    Using the reverse micelle which consisted of the surfactant of the cations, it succeeded in DNA extraction of the salmon spermatozoon. The transfer of DNA formed in the isooctane from water phase to the reverse micelle is greatly dependent on type and ionic strength of the surfactant. By the surfactant of quaternary ammonium salt type with two long-chain alkyl units, the DNA which was charged anionic was efficiently extracted in the reverse micelle. (translated by NEDO)

  5. Hydrogen evolution and consumption in AOT–isooctane reverse micelles by Desulfovibrio gigas hydrogenase

    OpenAIRE

    Moura, José J. G.; Andrade, Susana L. A.

    2002-01-01

    The enzyme hydrogenase isolated from the sulphate reducing anaerobic bacterium Desulfovibrio gigas was encapsulated in reverse micelles of AOT–water–isooctane. The enzyme ability to consume molecular hydrogen was studied as a function of the micelle size (given by Wo = [H2O]/[organic solvent]). A peak of catalytic activity was obtained for Wo = 18, a micelle size theoretically fitting the heterodimeric hydrogenase molecule. At this Wo value, the recorded catalytic activity was slightly ...

  6. 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...... 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)....

  7. 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.

  8. Structural changes of a sodium dodecyl sulfate (SDS) micelle induced by alcohol molecules.

    Science.gov (United States)

    Méndez-Bermúdez, Jose G; Dominguez, Hector

    2016-01-01

    Coarse-grained dynamical simulations have been performed to investigate the behavior of a surfactant micelle in the presence of six different alcohols: hexanol, octanol, decanol, dodecanol, tetradecanol, and hexadecanol. The self-assembly of sodium dodecyl sulfate (SDS) is modified by the alcohol molecules into cylindrical and bilayer micelles as a function of the alcohol/SDS mass ratio. Therefore, in order to understand, from a molecular point of view, how SDS and alcohol molecules self-organize to form the new micelles, different studies were carried out. Analysis of micelle structures, density profiles, and parameters of order were conducted to characterize the shape and size of those micelles. The density profiles revealed that the alcohol molecules were located at the water-micelle interface next to the SDS molecules at low alcohol/SDS mass ratio. At high alcohol/SDS mass ratios, alcohol molecules moved to the middle of the micelle by increasing their size and by producing a structural change. Moreover, micelle structures and sizes were influenced not only by the alcohol/SDS mass ratio but also by the order of the SDS and alcohol tails. Finally, the size of the micelles and enthalpy calculations were used as order parameters to determine a structural phase diagram of alcohol/SDS mixtures in water. Graphical Abstract Structural transition of SDS/alcohol mixtures.

  9. 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)

  10. Small angle neutron scattering study of the micelle structure of amphiphilic block copolymers

    International Nuclear Information System (INIS)

    Yamaoka, H.; Matsuoka, H.; Sumaru, K.; Hanada, S.

    1994-01-01

    The amphiphilic block copolymers of vinyl ether were prepared by living cationic polymerization. The partially deuterated copolymers for SANS experiments were especially synthesized by introducing deuterated phenyl units in the hydrophobic chain. SANS measurements were performed for aqueous solutions of these copolymers by changing H 2 O/D 2 O ratios. The SANS profiles indicate that the micelles in the present system exhibit a core-shell structure and that the size and shape of micelles are largely dependent on the length of hydrophobic chain. The micelle of shorter hydrophobic chain was found to be nearly spherical, whereas the micelle of longer hydrophobic chain was confirmed to have an ellipsoidal shape

  11. DNA-based approaches to identify forest fungi in Pacific Islands: A pilot study

    Science.gov (United States)

    Anna E. Case; Sara M. Ashiglar; Phil G. Cannon; Ernesto P. Militante; Edwin R. Tadiosa; Mutya Quintos-Manalo; Nelson M. Pampolina; John W. Hanna; Fred E. Brooks; Amy L. Ross-Davis; Mee-Sook Kim; Ned B. Klopfenstein

    2013-01-01

    DNA-based diagnostics have been successfully used to characterize diverse forest fungi (e.g., Hoff et al. 2004, Kim et al. 2006, Glaeser & Lindner 2011). DNA sequencing of the internal transcribed spacer (ITS) and large subunit (LSU) regions of nuclear ribosomal DNA (rDNA) has proved especially useful (Sonnenberg et al. 2007, Seifert 2009, Schoch et al. 2012) for...

  12. DNA-based identification and phylogeny of North American Armillaria species

    Science.gov (United States)

    Amy L. Ross-Davis; John W. Hanna; Ned B. Klopfenstein

    2011-01-01

    Because Armillaria species display different ecological behaviors across diverse forest ecosystems, it is critical to identify Armillaria species accurately for any assessment of forest health. To further develop DNA-based identification methods, partial sequences of the translation elongation factor-1 alpha (EF-1α) gene were used to examine the phylogenetic...

  13. DNA-based identification of Armillaria isolates from peach orchards in Mexico state

    Science.gov (United States)

    Ruben Damian Elias Roman; Ned B. Klopfenstein; Dionicio Alvarado Rosales; Mee-Sook Kim; Anna E. Case; Sara M. Ashiglar; John W. Hanna; Amy L. Ross-Davis; Remigio A. Guzman Plazola

    2012-01-01

    A collaborative project between the Programa de Fitopatología, Colegio de Postgraduados, Texcoco, Estado de Mexico and the USDA Forest Service - RMRS, Moscow Forest Pathology Laboratory has begun this year (2011) to assess which species of Armillaria are causing widespread and severe damage to the peach orchards from México state, Mexico. We are employing a DNA-based...

  14. DNA-based stable isotope probing: a link between community structure and function

    Czech Academy of Sciences Publication Activity Database

    Uhlík, Ondřej; Ječná, K.; Leigh, M. B.; Macková, Martina; Macek, Tomáš

    2009-01-01

    Roč. 407, č. 12 (2009), s. 3611-3619 ISSN 0048-9697 Grant - others:GA MŠk(CZ) 2B08031 Program:2B Institutional research plan: CEZ:AV0Z40550506 Keywords : DNA-based stable isotope probing * microbial diversity * bioremediation Subject RIV: EI - Biotechnology ; Bionics Impact factor: 2.905, year: 2009

  15. DNA-based asymmetric catalysis : Sequence-dependent rate acceleration and enantioselectivity

    NARCIS (Netherlands)

    Boersma, Arnold J.; Klijn, Jaap E.; Feringa, Ben L.; Roelfes, Gerard

    2008-01-01

    This study shows that the role of DNA in the DNA-based enantioselective Diels-Alder reaction of azachalcone with cyclopentadiene is not limited to that of a chiral scaffold. DNA in combination with the copper complex of 4,4'-dimethyl-2,2'-bipyridine (Cu-L1) gives rise to a rate acceleration of up to

  16. A DNA-based system for selecting and displaying the combined result of two input variables

    DEFF Research Database (Denmark)

    Liu, Huajie; Wang, Jianbang; Song, S

    2015-01-01

    demonstrate this capability in a DNA-based system that takes two input numbers, represented in DNA strands, and returns the result of their multiplication, writing this as a number in a display. Unlike a conventional calculator, this system operates by selecting the result from a library of solutions rather...

  17. Fast parallel DNA-based algorithms for molecular computation: the set-partition problem.

    Science.gov (United States)

    Chang, Weng-Long

    2007-12-01

    This paper demonstrates that basic biological operations can be used to solve the set-partition problem. In order to achieve this, we propose three DNA-based algorithms, a signed parallel adder, a signed parallel subtractor and a signed parallel comparator, that formally verify our designed molecular solutions for solving the set-partition problem.

  18. TAA Polyepitope DNA-Based Vaccines: A Potential Tool for Cancer Therapy

    Directory of Open Access Journals (Sweden)

    Roberto Bei

    2010-01-01

    Full Text Available DNA-based cancer vaccines represent an attractive strategy for inducing immunity to tumor associated antigens (TAAs in cancer patients. The demonstration that the delivery of a recombinant plasmid encoding epitopes can lead to epitope production, processing, and presentation to CD8+ T-lymphocytes, and the advantage of using a single DNA construct encoding multiple epitopes of one or more TAAs to elicit a broad spectrum of cytotoxic T-lymphocytes has encouraged the development of a variety of strategies aimed at increasing immunogenicity of TAA polyepitope DNA-based vaccines. The polyepitope DNA-based cancer vaccine approach can (a circumvent the variability of peptide presentation by tumor cells, (b allow the introduction in the plasmid construct of multiple immunogenic epitopes including heteroclitic epitope versions, and (c permit to enroll patients with different major histocompatibility complex (MHC haplotypes. This review will discuss the rationale for using the TAA polyepitope DNA-based vaccination strategy and recent results corroborating the usefulness of DNA encoding polyepitope vaccines as a potential tool for cancer therapy.

  19. 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

    International Nuclear Information System (INIS)

    Cuong, Nguyen-Van; Jiang, Jian-Lin; Li, Yu-Lun; Chen, Jim-Ray; Jwo, Shyh-Chuan; Hsieh, Ming-Fa

    2010-01-01

    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

  20. 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.

  1. 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.

  2. Micelle-like nanoassemblies based on polymer-drug conjugates as an emerging platform for drug delivery.

    Science.gov (United States)

    Liu, Zhihong; Wang, Yutao; Zhang, Na

    2012-07-01

    During the past decades, polymer-drug conjugates are one of the hottest topics in novel drug development fields. Amphiphilic polymer-drug conjugates in aqueous solution could form micelles or micelle-like nanoassemblies. Compared with polymer-drug conjugates and the micelles into which drugs are physically entrapped, micelles or micelle-like nanoassemblies based on polymer-drug conjugates bring several additional advantages, including increased drug-loading capacity, enhanced intracellular uptake, reduced systemic toxicity, and improved therapeutic efficacy. This review focuses on recent progress achieved in the research field of micelles or micelle-like nanoassemblies based on polymer-drug conjugates. Firstly, properties of polymers, drugs, and linkers which could be used to build polymer-drug conjugate micelles or micelle-like nanoassemblies are summarized. Then, the characterization methods are described. Finally, the drug-targeting mechanisms are discussed. Micelles or micelle-like nanoassemblies based on polymer-drug conjugates as an emerging platform have the potential to achieve medical treatments with enhanced therapeutic effect. The application of micelles or micelle-like nanoassemblies based on polymer-drug conjugates may give new life to old active compounds abandoned due to their low solubility problems. For clinical application, there is a need to further optimize the properties of the polymer, drug, and linker.

  3. Glutathione-responsive core cross-linked micelles for controlled cabazitaxel delivery

    Science.gov (United States)

    Han, Xiaoxiong; Gong, Feirong; Sun, Jing; Li, Yueqi; Liu, XiaoFei; Chen, Dan; Liu, Jianwen; Shen, Yaling

    2018-02-01

    Stimulus-responsive polymeric micelles (PMs) have recently received attention due to the controlled delivery of drug or gene for application in cancer diagnosis and treatment. In this work, novel glutathione-responsive PMs were prepared to encapsulate hydrophobic antineoplastic drug, cabazitaxel (CTX), to improve its solubility and toxicity. These CTX-loaded micelles core cross-linked by disulfide bonds (DCL-CTX micelles) were prepared by a novel copolymer, lipoic acid grafted mPEG-PLA. These micelles had regular spherical shape, homogeneous diameter of 18.97 ± 0.23 nm, and a narrow size distribution. The DCL-CTX micelles showed high encapsulation efficiency of 98.65 ± 1.77%, and the aqueous solubility of CTX was improved by a factor of 1:1200. In vitro release investigation showed that DCL-CTX micelles were stable in the medium without glutathione (GSH), whereas the micelles had burst CTX release in the medium with 10 mM GSH. Cell uptake results implied that DCL-CTX micelles were internalized into MCF-7 cells through clathrin-mediated endocytosis and released cargo more effectively than Jevtana (commercially available CTX) owing to GSH-stimulated degradation. In MTT assay against MCF-7 cells, these micelles inhibited tumor cell proliferation more effectively than Jevtana due to their GSH-responsive CTX release. All results revealed the potency of GSH-responsive DCL-CTX micelles for stable delivery in blood circulation and for intracellular GSH-trigged release of CTX. Therefore, DCL-CTX micelles show potential as safe and effective CTX delivery carriers and as a cancer chemotherapy formulation.

  4. 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)

  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. 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

  7. Self-consistent field modeling of linear non-ionic micelles

    NARCIS (Netherlands)

    Jodar-Reyes, A.B.; Leermakers, F.A.M.

    2006-01-01

    A self-consistent field theory is used to predict structural, mechanical, and thermodynamical properties of linear micelles of selected nonionic surfactants of the type CnEm. Upon increase in surfactant concentration the sudden micelle shape transition from spherical to cylindrical (second critical

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

    Indian Academy of Sciences (India)

    structure factor S(q) is governed by the volume fraction and surface charge of the micelles and the ionic strength of the medium. The ionic strength is fixed by the concentration of unassociated surfactant molecules and counterions arising from added hydrophobic molecules. No accounting of the polydispersity of the micelles.

  9. 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.

  10. Effects of gamma-irradiation on some properties of bovine casein micelles

    International Nuclear Information System (INIS)

    Saito, Zenichi

    1974-01-01

    Sedimentation studies and electron microscopic observations revealed that an association between casein micelles dispersed in water or milk serum was not induced significantly by gamma-irradiation of exposure up to 3 x 10 6 R, whereas a release of nonprotein nitrogen was observed to a certain extent. It was concluded from the results of turbidi-metry and gel filtration using 3 size groups of casein micelles, namely large, medium and small, that an irradiation-induced polymerization or association occurred within individual casein micelles, and strengthend the micelle structure. Thus the irradiated casein micelles resisted, more or less, to the solubilizing effect of NaCl, EDTA, pyrophosphate and urea. Stabilities of casein micelles for ethanol and for acidification to an isoelectric point were decreased and increased, respectively, after irradiation. Gamma irradiation also caused the decrease of glycomacropeptide released from casein micelles by the action of rennin, and this resulted in the delay of rennin-coagulation of casein. There were no essential differences among the 3 size groups of casein micelles concerning the above described tendencies. (auth.)

  11. 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.

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

    NARCIS (Netherlands)

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

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  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, Kim Lambertsen

    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. Radiolabeling polymeric micelles for in vivo evaluation : a novel, fast, and facile method

    NARCIS (Netherlands)

    Laan, A.C.; Santini, Costanza; Jennings, Laurence; de Jong, Marion; Bernsen, Monique R.; Denkova, A.G.

    2016-01-01

    Background: Single photon emission computed tomography (SPECT) is an indispensable tool in the determination of the in vivo fate of polymeric micelles. However, for this purpose, the micelles need to be radiolabeled, and almost all radiolabeling procedures published to date involve the

  16. Radiolabeling polymeric micelles for in vivo evaluation: a novel, fast, and facile method

    NARCIS (Netherlands)

    A.C. Laan (Adrianus C.); C. Santini (Costanza); L. Jennings (Laurence); M. De Jong (Marion); M.R. Bernsen (Monique); A.G. Denkova (Antonia G.)

    2016-01-01

    textabstractBackground: Single photon emission computed tomography (SPECT) is an indispensable tool in the determination of the in vivo fate of polymeric micelles. However, for this purpose, the micelles need to be radiolabeled, and almost all radiolabeling procedures published to date involve the

  17. Radiolabeling polymeric micelles for in vivo evaluation : A novel, fast, and facile method

    NARCIS (Netherlands)

    Laan, A.C.; Santini, C.; Jennings, L.; De Jong, M.; Bernsen, M.R.; Denkova, A.G.

    2016-01-01

    Background Single photon emission computed tomography (SPECT) is an indispensable tool in the determination of the in vivo fate of polymeric micelles. However, for this purpose, the micelles need to be radiolabeled, and almost all radiolabeling procedures published to date involve the conjugation of

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

    NARCIS (Netherlands)

    Lindhoud, Saskia; Cohen Stuart, Martinus Abraham; Norde, Willem; Leermakers, Frans 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

  19. Thermoresponsive hydrolytically degradable polymer micelles intended for radionuclide delivery

    Czech Academy of Sciences Publication Activity Database

    Hrubý, Martin; Koňák, Čestmír; Filippov, Sergey K.; Kučka, Jan; Větvička, David; Macková, Hana; Karlsson, G.; Edwards, K.; Říhová, Blanka; Ulbrich, Karel

    2009-01-01

    Roč. 9, č. 10 (2009), s. 1016-1027 ISSN 1616-5187 R&D Projects: GA AV ČR KAN200200651; GA ČR GA202/09/2078; GA ČR GD310/08/H077; GA MŠk 1M0505 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z50200510; CEZ:AV0Z10480505 Keywords : block-copolymer micelles * drug-delivery * systems Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.108, year: 2009

  20. Folding Behaviors of Protein (Lysozyme) Confined in Polyelectrolyte Complex Micelle.

    Science.gov (United States)

    Wu, Fu-Gen; Jiang, Yao-Wen; Chen, Zhan; Yu, Zhi-Wu

    2016-04-19

    The folding/unfolding behavior of proteins (enzymes) in confined space is important for their properties and functions, but such a behavior remains largely unexplored. In this article, we reported our finding that lysozyme and a double hydrophilic block copolymer, methoxypoly(ethylene glycol)5K-block-poly(l-aspartic acid sodium salt)10 (mPEG(5K)-b-PLD10), can form a polyelectrolyte complex micelle with a particle size of ∼30 nm, as verified by dynamic light scattering and transmission electron microscopy. The unfolding and refolding behaviors of lysozyme molecules in the presence of the copolymer were studied by microcalorimetry and circular dichroism spectroscopy. Upon complex formation with mPEG(5K)-b-PLD10, lysozyme changed from its initial native state to a new partially unfolded state. Compared with its native state, this copolymer-complexed new folding state of lysozyme has different secondary and tertiary structures, a decreased thermostability, and significantly altered unfolding/refolding behaviors. It was found that the native lysozyme exhibited reversible unfolding and refolding upon heating and subsequent cooling, while lysozyme in the new folding state (complexed with the oppositely charged PLD segments of the polymer) could unfold upon heating but could not refold upon subsequent cooling. By employing the heating-cooling-reheating procedure, the prevention of complex formation between lysozyme and polymer due to the salt screening effect was observed, and the resulting uncomplexed lysozyme regained its proper unfolding and refolding abilities upon heating and subsequent cooling. Besides, we also pointed out the important role the length of the PLD segment played during the formation of micelles and the monodispersity of the formed micelles. Furthermore, the lysozyme-mPEG(5K)-b-PLD10 mixtures prepared in this work were all transparent, without the formation of large aggregates or precipitates in solution as frequently observed in other protein

  1. 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...... composition. The data analysis comprises an application from results of conformation space renormalization group theory and a non-linear least-squares fitting procedure based upon a recently developed numerical expression for the scattering function of a worm-like chain with excluded volume effects....

  2. 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

  3. Complex and hierarchical micelle architectures from diblock copolymers using living, crystallization-driven polymerizations

    Science.gov (United States)

    Gädt, Torben; Ieong, Nga Sze; Cambridge, Graeme; Winnik, Mitchell A.; Manners, Ian

    2009-02-01

    Block copolymers consist of two or more chemically distinct polymer segments, or blocks, connected by a covalent link. In a selective solvent for one of the blocks, core-corona micelle structures are formed. We demonstrate that living polymerizations driven by the epitaxial crystallization of a core-forming metalloblock represent a synthetic tool that can be used to generate complex and hierarchical micelle architectures from diblock copolymers. The use of platelet micelles as initiators enables the formation of scarf-like architectures in which cylindrical micelle tassels of controlled length are grown from specific crystal faces. A similar process enables the fabrication of brushes of cylindrical micelles on a crystalline homopolymer substrate. Living polymerizations driven by heteroepitaxial growth can also be accomplished and are illustrated by the formation of tri- and pentablock and scarf architectures with cylinder-cylinder and platelet-cylinder connections, respectively, that involve different core-forming metalloblocks.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-09-15

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

  5. Polyion complex micelles prepared by self-assembly of block-graft polycation and hyperbranched polyanion

    Science.gov (United States)

    Dai, Yu; Wang, Hongquan; Zhang, Xiaojin

    2017-09-01

    Polyion complex (PIC) micelles were prepared by self-assembly of block-graft polycation monomethoxy poly(ethylene glycol)- block-(poly(ɛ-caprolactone)- graft-polyethylenimine) (PEG- b-(PCL- g-PEI)) and hyperbranched polyanion sodium carboxyl-modified hyperbranched polyesters (Hx-COONa, x = 20, 30, 40). The results from commonly used MTT assay indicated that PIC micelles had good biocompatibility. PIC micelles with N/COO- of 8/3 had appropriate size (sub-110 nm) and moderate zeta potential ( 3 mV). PIC micelles were nano-sized spheres, and the average size was about 50 nm. PIC micelles had high drug loading capacity for hydrophilic drugs such as doxorubicin (DOX) hydrochloride and released the drugs under the influence of pH and ionic strength.

  6. From DNA Bases to Ultracold Atoms: Probing Ensembles Using Supersonic Beams

    Science.gov (United States)

    Smith, Valoris Reid

    This thesis discusses two ensembles, the study of which was dependent upon the controllable production of cold gas-phase samples using supersonic beams. The experiments on DNA bases and base clusters were carried out in Germany at the Max Born Institute. The experiments anticipating the construction of a molecular beam slower were carried out in the United States at the University of Texas at Austin. Femtosecond pump-probe techniques were employed to study the dynamics and electronic character of DNA bases, pairs and clusters in the gas phase. Experimentsnon DNA base monomers confirmed the dominance of a particular relaxation pathway, the npi* state. Competition between this state and another proposed relaxation pathway was demonstrated through observations of the DNA base pairs and base-water clusters, settling a recent controversy. Further, it was determined that the excited state dynamics in base pairs is due to intramolecular processes rather than intermolecular processes. Finally, results from base-water clusters confirm that microsolvation permits comparison with biologically relevant liquid phase experiments and with ab initio calculations, bridging a long-standing gap. A purely mechanical technique that does not rely upon quantum or electronic properties to produce very cold, very slow atoms and molecules would be more generally applicable than current approaches. The approach described here uses supersonic beam methods to produce a very cold beam of particles and a rotating paddle-wheel, or rotor, to slow the cold beam. Initial experiments testing the possibility of elastic scattering from a single crystal surface were conducted and the implications of these experiments are discussed.

  7. The role of DNA base excision repair in brain homeostasis and disease

    DEFF Research Database (Denmark)

    Akbari, Mansour; Morevati, Marya; Croteau, Deborah

    2015-01-01

    Chemical modification and spontaneous loss of nucleotide bases from DNA are estimated to occur at the rate of thousands per human cell per day. DNA base excision repair (BER) is a critical mechanism for repairing such lesions in nuclear and mitochondrial DNA. Defective expression or function of p...... energy homeostasis, mitochondrial function and cellular bioenergetics, with especially strong influence on neurological function. Further studies in this area could lead to novel approaches to prevent and treat human neurodegenerative disease....

  8. Quantification of Plasmodiophora brassicae Using a DNA-Based Soil Test Facilitates Sustainable Oilseed Rape Production

    OpenAIRE

    Ann-Charlotte Wallenhammar; Albin Gunnarson; Fredrik Hansson; Anders Jonsson

    2016-01-01

    Outbreaks of clubroot disease caused by the soil-borne obligate parasite Plasmodiophora brassicae are common in oilseed rape (OSR) in Sweden. A DNA-based soil testing service that identifies fields where P. brassicae poses a significant risk of clubroot infection is now commercially available. It was applied here in field surveys to monitor the prevalence of P. brassicae DNA in field soils intended for winter OSR production and winter OSR field experiments. In 2013 in Scania, prior to plantin...

  9. Proton Relaxation and Spin Label Studies of Papaverine Localization in Ionic Micelles

    Science.gov (United States)

    Yushmanov, V. E.; Imasato, H.; Perussi, J. R.; Tabak, M.

    The localization of papaverine (PAV) in micelles of zwitterionic N-hexadecyl- N, N-dimethyl-3-ammonio-1-propanesulfonate (HPS), cationic cetyltrimethylammonium chloride (CTAC), and anionic sodium dodecyl sulfate (SDS) in D 2O was studied by 1H NMR and ESR in the presence and absence of 5-doxyl- or 12-doxyl-stearic acid. PAV, surfactants, and spin probes are characterized by restricted anisotropic motion in micelles. The rotational correlation time of doxyl fragment was in the range of 0.2 to 0.5 nanoseconds. Binding of PAV to micelles decreases the mobility of both probes, suggesting the localization of PAV inside the hydrophobic part of micelles near the micelle-water interface. According to the NOE data, the methoxy groups of PAV are located in the vicinity of the nitrogen atom in CTAC and HPS micelles, the methoxy groups of the PAV heterocycle being immersed slightly deeper inside the micelle. The T1 relaxation enhancements by two different spin probes show that the H5 and methoxy substituents of the PAV heterocycle are in close proximity to the α-CH 2 of acyl chains in all types of micelles, whereas H3 and H12 are the most distant from the α-CH 2. No significant differences were found for the protonated and neutral PAV in SDS micelles at pD 4.9 and 11.2. These data show that the geometry of the PAV-micelle complex is practically independent of the PAV charge and surfactant headgroup.

  10. Correlation dynamics and enhanced signals for the identification of serial biomolecules and DNA bases

    International Nuclear Information System (INIS)

    Ahmed, Towfiq; Haraldsen, Jason T; Balatsky, Alexander V; Rehr, John J; Di Ventra, Massimiliano; Schuller, Ivan

    2014-01-01

    Nanopore-based sequencing has demonstrated a significant potential for the development of fast, accurate, and cost-efficient fingerprinting techniques for next generation molecular detection and sequencing. We propose a specific multilayered graphene-based nanopore device architecture for the recognition of single biomolecules. Molecular detection and analysis can be accomplished through the detection of transverse currents as the molecule or DNA base translocates through the nanopore. To increase the overall signal-to-noise ratio and the accuracy, we implement a new ‘multi-point cross-correlation’ technique for identification of DNA bases or other molecules on the single molecular level. We demonstrate that the cross-correlations between each nanopore will greatly enhance the transverse current signal for each molecule. We implement first-principles transport calculations for DNA bases surveyed across a multilayered graphene nanopore system to illustrate the advantages of the proposed geometry. A time-series analysis of the cross-correlation functions illustrates the potential of this method for enhancing the signal-to-noise ratio. This work constitutes a significant step forward in facilitating fingerprinting of single biomolecules using solid state technology. (paper)

  11. Correlation dynamics and enhanced signals for the identification of serial biomolecules and DNA bases

    Science.gov (United States)

    Ahmed, Towfiq; Haraldsen, Jason T.; Rehr, John J.; Di Ventra, Massimiliano; Schuller, Ivan; Balatsky, Alexander V.

    2014-03-01

    Nanopore-based sequencing has demonstrated a significant potential for the development of fast, accurate, and cost-efficient fingerprinting techniques for next generation molecular detection and sequencing. We propose a specific multilayered graphene-based nanopore device architecture for the recognition of single biomolecules. Molecular detection and analysis can be accomplished through the detection of transverse currents as the molecule or DNA base translocates through the nanopore. To increase the overall signal-to-noise ratio and the accuracy, we implement a new ‘multi-point cross-correlation’ technique for identification of DNA bases or other molecules on the single molecular level. We demonstrate that the cross-correlations between each nanopore will greatly enhance the transverse current signal for each molecule. We implement first-principles transport calculations for DNA bases surveyed across a multilayered graphene nanopore system to illustrate the advantages of the proposed geometry. A time-series analysis of the cross-correlation functions illustrates the potential of this method for enhancing the signal-to-noise ratio. This work constitutes a significant step forward in facilitating fingerprinting of single biomolecules using solid state technology.

  12. Analyte focusing by micelle collapse in CZE: nanopreparation of neutrals.

    Science.gov (United States)

    Quirino, Joselito P

    2009-03-01

    Fundamental studies on the nanopreparation of neutral analytes in CZE by analyte focusing by micelle collapse (AFMC) are presented. The background solution (BGS) is prepared using an electrolyte salt (i.e. sodium or ammonium acetate). The sample solution of the neutral analytes (S) is prepared using SDS at a concentration above the cmc. To induce AFMC, the conductivity of the S must be greater than the BGS. This was achieved by the addition of the electrolyte salt to the S. Dilution of the micellar carrier from the injected S occurs at the BGS zone closest to the boundary between the S and BGS (micellar dilution zone). The dilution of SDS below the cmc causes the collapse of the micelles with subsequent release of previously bound analyte molecules. The continued transport and release causes the analytes to be accumulated at the micellar dilution zone. This nanopreparative technique is compatible with detection using mass spectrometry and can be utilized as a sample injection step for microfluidic devices. The disadvantage of this technique is that the neutral analytes are not separated after concentration. Here, the effect of retention factor of the analyte, conductivity ratio of the S and BGS, SDS concentration in the S, electrolyte salt (i.e. sodium acetate) concentration in the BGS, and organic modifier content in the BGS were examined. A study on the effect of the sample matrix injection prior to the sample injection to the performance of AFMC-CZE to neutral analytes is also presented.

  13. Self-Assembly of Calix[4]arene-Based Amphiphiles Bearing Polyethylene Glycols: Another Example of "Platonic Micelles".

    Science.gov (United States)

    Yoshida, Kenta; Fujii, Shota; Takahashi, Rintaro; Matsumoto, Sakiko; Sakurai, Kazuo

    2017-09-12

    The aggregation number of classical micelles exhibits a certain distribution, which is a recognizable feature of conventional micelles. However, we recently identified perfectly monodisperse calix[4]arene-based micelles whose aggregation numbers agree with the vertex numbers of regular polyhedra, that is, Platonic solids, and thus they are named "Platonic micelles". Regarding our hypothesis of the formation mechanism of Platonic micelles, both repulsive interactions including steric hindrance and electrostatic repulsions among the headgroups are important for determining their aggregation number; however, neither of these is necessarily needed to consider. In this study, we employed polyethylene glycols (PEGs) as the nonionic headgroup of calix[4]arene-based amphiphiles to study the effects of only repulsive interactions caused by steric hindrance on the formation of Platonic micelles. The amphiphiles containing relatively low-molecular-weight PEGs (550 or 1000 g mol -1 ) form dodecamer or octamer micelles, respectively, with no variation in the aggregation number. However, relatively high-molecular-weight PEGs (2000 g mol -1 ) produce polydispersed micelles with a range of aggregation number. PEG 2000 exhibits a greater affinity for water than PEG 550 and 1000, resulting in fewer hydrophobic interactions in micelle formation, as indicated by the drastic increase of the critical micelle concentration (CMC) value in the PEG 2000 system. The instability of the structure of PEG 2k CaL5 micelles might contribute to the higher mobility of PEG in the micellar shell, resulting in a non-Platonic aggregation number with polydispersity.

  14. Biodegradable self-assembled PEG-PCL-PEG micelles for hydrophobic honokiol delivery: I. Preparation and characterization

    International Nuclear Information System (INIS)

    Gong Changyang; Wei Xiawei; Wang Xiuhong; Wang Yujun; Guo Gang; Mao Yongqiu; Luo Feng; Qian Zhiyong

    2010-01-01

    This study aims to develop self-assembled poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) micelles to encapsulate hydrophobic honokiol (HK) in order to overcome its poor water solubility and to meet the requirement of intravenous administration. Honokiol loaded micelles (HK-micelles) were prepared by self-assembly of PECE copolymer in aqueous solution, triggered by its amphiphilic characteristic assisted by ultrasonication without any organic solvents, surfactants and vigorous stirring. The particle size of the prepared HK-micelles measured by Malvern laser particle size analyzer were 58 nm, which is small enough to be a candidate for an intravenous drug delivery system. Furthermore, the HK-micelles could be lyophilized into powder without any adjuvant, and the re-dissolved HK-micelles are stable and homogeneous with particle size about 61 nm. Furthermore, the in vitro release profile showed a significant difference between the rapid release of free HK and the much slower and sustained release of HK-micelles. Moreover, the cytotoxicity results of blank micelles and HK-micelles showed that the PECE micelle was a safe carrier and the encapsulated HK retained its potent antitumor effect. In short, the HK-micelles were successfully prepared by an improved method and might be promising carriers for intravenous delivery of HK in cancer chemotherapy, being effective, stable, safe (organic solvent and surfactant free), and easy to produce and scale up.

  15. Biodegradable self-assembled PEG-PCL-PEG micelles for hydrophobic honokiol delivery: I. Preparation and characterization

    Science.gov (United States)

    Gong, ChangYang; Wei, XiaWei; Wang, XiuHong; Wang, YuJun; Guo, Gang; Mao, YongQiu; Luo, Feng; Qian, ZhiYong

    2010-05-01

    This study aims to develop self-assembled poly(ethylene glycol)-poly(ɛ-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) micelles to encapsulate hydrophobic honokiol (HK) in order to overcome its poor water solubility and to meet the requirement of intravenous administration. Honokiol loaded micelles (HK-micelles) were prepared by self-assembly of PECE copolymer in aqueous solution, triggered by its amphiphilic characteristic assisted by ultrasonication without any organic solvents, surfactants and vigorous stirring. The particle size of the prepared HK-micelles measured by Malvern laser particle size analyzer were 58 nm, which is small enough to be a candidate for an intravenous drug delivery system. Furthermore, the HK-micelles could be lyophilized into powder without any adjuvant, and the re-dissolved HK-micelles are stable and homogeneous with particle size about 61 nm. Furthermore, the in vitro release profile showed a significant difference between the rapid release of free HK and the much slower and sustained release of HK-micelles. Moreover, the cytotoxicity results of blank micelles and HK-micelles showed that the PECE micelle was a safe carrier and the encapsulated HK retained its potent antitumor effect. In short, the HK-micelles were successfully prepared by an improved method and might be promising carriers for intravenous delivery of HK in cancer chemotherapy, being effective, stable, safe (organic solvent and surfactant free), and easy to produce and scale up.

  16. Influence of serum albumin on intracellular delivery of drug-loaded hyaluronan polymeric micelles.

    Science.gov (United States)

    Nešporová, Kristina; Šógorková, Jana; Šmejkalová, Daniela; Kulhánek, Jaromír; Huerta-Angeles, Gloria; Kubala, Lukáš; Velebný, Vladimír

    2016-09-10

    Polymeric micelles are attractive drug delivery systems for intravenously administered nonpolar drugs. Although physical parameters like size, shape and loading capacity are considered as the most important for their efficiency, here we demonstrate that the effects of serum protein interaction and characteristics of loaded compound cannot be neglected during the micelle development and design of experimental set up. Polymeric micelles prepared from amphiphilic hyaluronic acid grafted with short (hexanoic) and long fatty acids (oleic) were tested after loading with two different hydrophobic models, Nile red and curcumin. The composition of micelles affected mainly the loading capacity. Both encapsulated compounds behaved differently in the in vitro cell uptake, which was also influenced by serum concentration, where serum albumin was found to be the primary destabilizing component. This destabilization was found to be influenced by polymeric micelle concentration. Thus, the chemical structure of micelle, the properties of non-covalently loaded substance and serum albumin/polymeric micelle ratio modulate the in vitro intracellular uptake of drugs loaded in nanocarriers. Copyright © 2016. Published by Elsevier B.V.

  17. 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.

  18. 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

    2016-05-25

    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.

  19. In vitro evaluation of antioxidant and neuroprotective effects of curcumin loaded in Pluronic micelles

    Directory of Open Access Journals (Sweden)

    Cvetelina Gorinova

    2016-09-01

    Full Text Available Curcumin is a polyphenolic substance with attractive pharmacological activities (e.g. antioxidant, anti-inflammatory, anticancer. Incorporation of curcumin in polymeric micelles could overcome the problems associated with its instability and low aqueous solubility. The aim of this study was to load curcumin in polymeric micelles based on Pluronic® P 123 or Pluronic® F 127 triblock copolymers and evaluate the antioxidant and neuroprotective effects after micellization. The micelles were prepared and loaded with curcumin by applying the dissolution method. Higher encapsulation efficiency was observed in the micelles formulated with Pluronic® P 123. These micelles were characterized with small size and narrow size distribution. The effects of micellar curcumin were investigated in two in vitro models. First, the capacity of micellar curcumin to inhibit iron/ascorbic acid-induced lipid peroxidation in rat liver microsomes was evaluated. Micellar curcumin and free drug showed similar inhibition of lipid peroxidation. Second, micellar curcumin and free curcumin showed protective potential in a model of 6-hydroxydopamine induced neurotoxicity in rat brain synaptosomes. The results from both methods indicated preservation of antioxidant and neuroprotective activity of curcumin in micelles. The small micellar size, high loading capacity and preservation of antioxidant activity of curcumin into Pluronic micelles, suggested their further evaluation as a curcumin delivery system.

  20. Microstructural observation of casein micelles in milk by cryo-electron microscopy of vitreous sections (CEMOVIS).

    Science.gov (United States)

    Kamigaki, Takamichi; Ito, Yosiko; Nishino, Yuri; Miyazawa, Atsuo

    2018-03-02

    Casein micelles are present in bovine milk as colloidal particles with diameters of 20-600 nm, which are complex macromolecular assemblies composed of four distinct types of casein and colloidal calcium phosphate (CCP). Multiple structural models of casein micelles have been proposed based on their biochemical or physical properties and observed using electron microscopy. However, the CCP distribution and crosslinking structure between CCP and casein remain unclear. Therefore, the internal structure of casein micelles in raw milk was observed using cryo-electron microscopy of vitreous sections (CEMOVIS) with high precision at high resolution. The results confirmed that the average casein micelle diameter was about 140 nm, and that the CCP diameter in casein micelles was about 2-3 nm, with an average diameter of 2.3 nm. The distribution of CCP in casein micelles was not uniform, with an average interval between CCPs of about 5.4 nm. Areas containing no black particles (attributed to CCP) were present, with an average size of about 19.1 nm. Considering previous reports, these areas possibly correspond to pores or cavities filled with water. Based on differences in the density of structures in casein micelles, we estimated that some of the casein aggregates were able to connect with CCP in a string.

  1. pH-Responsive Micelle-Based Cytoplasmic Delivery System for Induction of Cellular Immunity

    Directory of Open Access Journals (Sweden)

    Eiji Yuba

    2017-11-01

    Full Text Available (1 Background: Cytoplasmic delivery of antigens is crucial for the induction of cellular immunity, which is an important immune response for the treatment of cancer and infectious diseases. To date, fusogenic protein-incorporated liposomes and pH-responsive polymer-modified liposomes have been used to achieve cytoplasmic delivery of antigen via membrane rupture or fusion with endosomes. However, a more versatile cytoplasmic delivery system is desired for practical use. For this study, we developed pH-responsive micelles composed of dilauroyl phosphatidylcholine (DLPC and deoxycholic acid and investigated their cytoplasmic delivery performance and immunity-inducing capability. (2 Methods: Interaction of micelles with fluorescence dye-loaded liposomes, intracellular distribution of micelles, and antigenic proteins were observed. Finally, antigen-specific cellular immune response was evaluated in vivo using ELIspot assay. (3 Results: Micelles induced leakage of contents from liposomes via lipid mixing at low pH. Micelles were taken up by dendritic cells mainly via macropinocytosis and delivered ovalbumin (OVA into the cytosol. After intradermal injection of micelles and OVA, OVA-specific cellular immunity was induced in the spleen. (4 Conclusions: pH-responsive micelles composed of DLPC and deoxycholic acid are promising as enhancers of cytosol delivery of antigens and the induction capability of cellular immunity for the treatment of cancer immunotherapy and infectious diseases.

  2. Long circulating micelles of an amphiphilic random copolymer bearing cell outer membrane phosphorylcholine zwitterions.

    Science.gov (United States)

    Zhao, Jing; Chai, Yu-Dong; Zhang, Jing; Huang, Peng-Fei; Nakashima, Kenichi; Gong, Yong-Kuan

    2015-04-01

    Polymeric micelles with cell outer membrane mimetic structure were prepared in water from amphiphilic random copolymers bearing both the hydrophilic phosphorylcholine zwitterions and hydrophobic octadecyl side chains of cell outer membrane. The polymeric micelles showed sizes ranging from 80 nm to 120 nm in hydrodynamic diameter and zeta-potentials from -6.4 mV to -2.4 mV by dynamic light scattering measurements. The micelles loaded with 6-coumarin as a fluorescence probe were stable to investigate their blood circulation and biodistribution. The in vitro phagocytosis results using murine peritoneal macrophages showed 10-fold reduction compared with a reference micelle. The in vivo blood circulation half-life of the polymeric micelles following intravenous administration in New Zealand Rabbits was increased from 0.55 h to 90.5h. More interestingly, tissue distribution results showed that the concentration of the micelles in the kidney is 4-fold higher than that in the liver and other organs 48 h after administration. The results of this work show great promise for designing more effective stealth drug carriers that can minimize reticuloendothelial system clearance and circulate for long time to reach target by using simple cell membrane mimetic random copolymer micelles. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. Micellization of St/MMA gradient copolymers: a general picture of structural transitions in gradient copolymer micelles.

    Science.gov (United States)

    Zheng, Chao; Huang, Haiying; He, Tianbai

    2013-10-01

    In this work, a gradient copolymer of styrene (St) and methyl methacrylate (MMA) is synthesized via reversible addition-fragmentation chain transfer living radical polymerization and its micellization behaviors in an acetone and water mixture are investigated by transmission electron microscopy, light scattering, and NMR spectroscopy. Three different kinds of transitions were found to coexist in a single system for the first time: a unimers to micelles transition, a star-like micelles to crew-cut micelles transition resulting from the shrinkage of micelles, and morphological transitions from spherical micelles to cylindrical micelles to vesicles. Our findings provide a general picture of structural transitions and relaxation processes in gradient copolymer micelles, which can lead to the development of novel materials and applications based on gradient copolymers. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jing; Luan, Shujuan; Qin, Benkai; Wang, Yingying; Wang, Kai; Qi, Peilan; Song, Shiyong, E-mail: pharmsong@henu.edu.cn [Henan University, Institute of Pharmacy (China)

    2016-11-15

    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.

  5. Nanotoxicity comparison of four amphiphilic polymeric micelles with similar hydrophilic or hydrophobic structure.

    Science.gov (United States)

    Zhao, Bo; Wang, Xue-Qing; Wang, Xiao-You; Zhang, Hua; Dai, Wen-Bing; Wang, Jun; Zhong, Zhen-Lin; Wu, Hou-Nan; Zhang, Qiang

    2013-10-03

    Nanocarriers represent an attractive means of drug delivery, but their biosafety must be established before their use in clinical research. Four kinds of amphiphilic polymeric (PEG-PG-PCL, PEEP-PCL, PEG-PCL and PEG-DSPE) micelles with similar hydrophilic or hydrophobic structure were prepared and their in vitro and in vivo safety were evaluated and compared. In vitro nanotoxicity evaluations included assessments of cell morphology, cell volume, inflammatory effects, cytotoxicity, apoptosis and membrane fluidity. An umbilical vein cell line (Eahy.926) and a kind of macrophages (J774.A1) were used as cell models considering that intravenous route is dominant for micelle delivery systems. In vivo analyses included complete blood count, lymphocyte subset analysis, detection of plasma inflammatory factors and histological observations of major organs after intravenous administration to KM mice. All the micelles enhanced inflammatory molecules in J774.A1 cells, likely resulting from the increased ROS levels. PEG-PG-PCL and PEEP-PCL micelles were found to increase the J774.A1 cell volume. This likely correlated with the size of PEG-PG-PCL micelles and the polyphosphoester structure in PEEP-PCL. PEG-DSPE micelles inhibited the growth of Eahy.926 cells via inducing apoptosis. This might relate to the structure of DSPE, which is a type of phospholipid and has good affinity with cell membrane. No evidence was found for cell membrane changes after treatment with these micelles for 24 h. In the in vivo study, during 8 days of 4 time injection, each of the four nanocarriers altered the hematic phase differently without changes in inflammatory factors or pathological changes in target organs. These results demonstrate that the micelles investigated exhibit diverse nanotoxicity correlated with their structures, their biosafety is different in different cell model, and there is no in vitro and in vivo correlation found. We believe that this study will certainly provide more

  6. 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 micelle diameter, diffuses out to the water-SDS interface and stabilizes to an interface-bound steady state in 16.35 ns of simulation. The final conformation, orientation, and the structure of ovispirin are in good agreement with the experimentally observed properties of the peptide in presence of lipid...

  7. 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......, when monitored by conventional stopped-flow. The kinetic data indicate that denaturation occurs around 0.3 mole fraction of SDS, in agreement with CD analysis and acrylamide quenching data. The rate constants have been fit to a three-state folding scheme involving the SDS-denatured state, the native...... state and an unfolding intermediate that accumulates only under unfolding conditions at high mole fractions of SDS. The stability of DsbB is around 4.4 kcal/mol in DM, and this is halved upon reduction of the two periplasmic disulfide bonds, and is sensitive to mutagenesis. With the caveat that kinetic...

  8. 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.

  9. Reverse micelles for the removal of dyes from aqueous solutions.

    Science.gov (United States)

    Majhi, S; Sharma, Y C; Upadhyay, S N

    2009-08-01

    The ability of reverse micelles to solvate organic dyes in the aqueous core was investigated with methyl orange (MO) and methylene blue (MB) using hexadecyl trimethyl ammonium bromide (HTAB) and sodium dodecyl benzene sulphonate (SDBS) surfactants in a polar amyl alcohol medium. The removal trend of the dyes from water was studied with different concentrations of the dyes. The effects of NaCl and CaCl2 salts on removal efficiency of the surfactants were investigated and results were compared. It was observed that the separation of dyes from the aqueous phase to the organic phase depends on the electrostatic interaction between the dye molecule and surfactant head groups. In the case of NaCl, with increasing salt concentration, the removal (%) of dye decreases. For CaCl2, removal of methyl orange shows a gradual increase with increasing dye concentration, whereas, for methylene blue, its removal decreases with increasing dye concentration.

  10. The elasticity of soap bubbles containing wormlike micelles.

    Science.gov (United States)

    Sabadini, Edvaldo; Ungarato, Rafael F S; Miranda, Paulo B

    2014-01-28

    Slow-motion imaging of the rupture of soap bubbles generally shows the edges of liquid films retracting at a constant speed (known as the Taylor-Culick velocity). Here we investigate soap bubbles formed from simple solutions of a cationic surfactant (cetyltrimethylammonium bromide - CTAB) and sodium salicylate. The interaction of salicylate ions with CTAB leads to the formation of wormlike micelles (WLM), which yield a viscoelastic behavior to the liquid film of the bubble. We demonstrate that these elastic bubbles collapse at a velocity up to 30 times higher than the Taylor-Culick limit, which has never been surpassed. This is because during the bubble inflation, the entangled WLM chains stretch, storing elastic energy. This extra energy is then released during the rupture of the bubble, yielding an additional driving force for film retraction (besides surface tension). This new mechanism for the bursting of elastic bubbles may have important implications to the breakup of viscoelastic sprays in industrial applications.

  11. Pseudogenes and DNA-based diet analyses: A cautionary tale from a relatively well sampled predator-prey system

    DEFF Research Database (Denmark)

    Dunshea, G.; Barros, N. B.; Wells, R. S.

    2008-01-01

    Mitochondrial ribosomal DNA is commonly used in DNA-based dietary analyses. In such studies, these sequences are generally assumed to be the only version present in DNA of the organism of interest. However, nuclear pseudogenes that display variable similarity to the mitochondrial versions are com...... be virtually impossible to determine whether a putative prey sequence is actually a pseudogene derived from either the predator or prey DNA. The implications of this for DNA-based dietary studies, in general, are discussed....

  12. 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)

  13. "Bottom-Up" Construction of Hyperbranched Poly(prodrug-co-photosensitizer) Amphiphiles Unimolecular Micelles for Chemo-Photodynamic Dual Therapy.

    Science.gov (United States)

    Sun, Pei; Wang, Nan; Jin, Xin; Zhu, Xinyuan

    2017-10-25

    Despite the great advantages of chemo-photodynamic combination therapy, tedious synthesis steps and laborious purification procedures make the fabrication of chemo-photodynamic combined therapeutic platforms rather difficult. In this study, we develop a facile "bottom-up" strategy to fabricate hyperbranched poly(prodrug-co-photosensitizer) amphiphiles, h-P(CPTMA-co-BYMAI)-b-POEGMA (hPCBE), for chemo-photodynamic dual therapy. The easily prepared hPCBE possess a bottom-up-constructed hydrophobic core h-P(CPTMA-co-BYMAI) (hPCB) direct copolymerized from reduction-responsive CPT prodrug monomer (CPTMA) and boron dipyrromethene-based photosensitizer monomer (BYMAI), as well as a biocompatible shell polymerized from hydrophilic monomers. Because of the covalently interconnected core-shell structure, hPCBE exists as unimolecular micelles in aqueous solution and exhibits excellent structural stability under dilution condition. The hPCBE micelles can be effectively internalized by MCF-7 cells and release CPT triggered by the reductive milieu. In addition, photosensitizer moieties embedded in the hPCB core could generate singlet oxygen ( 1 O 2 ) effectively under irradiation, endowing hPCBE with the boosting of chemotherapeutic efficacy. As compared to the single chemotherapy of hyperbranched polyprodrug amphiphiles h-PCPTMA-b-POEGMA (hPCE) and photodynamic therapy of hyperbranched polyphotosensitizer amphiphiles h-PBYMAI-b-POEGMA (hPBE), hPCBE shows higher in vitro cytotoxicity. We expect that our approach will further boost research on the design of multifunctional drug delivery systems via the facile "bottom-up" strategy.

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

    Science.gov (United States)

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

    2004-09-01

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

  15. Near-infrared light-triggered dissociation of block copolymer micelles for controlled drug release

    Science.gov (United States)

    Cao, Jie; Huang, Shanshan; Chen, Yuqi; Li, Siwen; Achilefu, Samuel; Qian, Zhiyu; Gu, Yueqing

    2013-02-01

    In this manuscript, a new near-infrared (NIR) light-breakable amphiphilic block copolymer containing light-sensitive triggering group on the hydrophobic block was developed. By encapsulating NIR dye cypate inside micelles of poly (N-succinyl-N'-4- (2-nitrobenzyloxy)-succinyl chitosan) and exposing the micellar solution to 765.9 nm light, the photo-cleavage reaction was activated and leading to the dissociation of micelles and release of co-loaded hydrophobic species. The UV-vis absorption spectra, fourier transform infrared (FTIR) spectra and 1H nuclear magnetic resonance (1H NMR) spectra of micelles were characterized. Triggered burst release of the payload upon NIR irradiation and subsequent degradation of the micelles were observed by transmission electron microscopy (TEM). This system represents a general and efficient method to circumvent the need for UV or visible light excitation that is a common drawback for light-responsive polymeric systems developed for potential biomedical applications.

  16. Electron transfer reactions of ruthenium(II) complexes with polyphenolic acids in micelles

    Energy Technology Data Exchange (ETDEWEB)

    Rajeswari, Angusamy [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India); Department of Chemistry, Fatima College, Madurai 625 018 (India); Ramdass, Arumugam [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India); Research Department of Chemistry, Aditanar College of Arts and Science, Tiruchendur 628 216 (India); Muthu Mareeswaran, Paulpandian [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India); Department of Industrial Chemistry, Alagappa University, Karaikudi 630 003 (India); Rajagopal, Seenivasan, E-mail: rajagopalseenivasan@yahoo.com [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India)

    2016-02-15

    The electron transfer in a microhetrogeneous system is a perfect mimic of biological electron transfer. The electron transfer between biologically important phenolic acids and ruthenium (II) complexes is systematically studied in the presence of anionic and cationic micelles. The photophysical properties of these ruthenium (II) complexes with anionic and cationic micelles and their binding abilities with these two type of micelles are also studies using absorption, emission and excited state lifetime spectral techniques. Pseudophase Ion Exchange (PIE) Model is applied to derive mechanism of electron transfer in two types of micelles. - Highlights: • Effect of microhetrogeneous system is studied using ruthenium (II) complexes and gallic acid is studied. • Pseudophase Ion exchange model is applied to derive the mechanism. • Binding constants are in the range of 10{sup 2}–10{sup 4} M{sup −1}.

  17. Influence of serum albumin on intracellular delivery of drug-loaded hyaluronan polymeric micelles

    Czech Academy of Sciences Publication Activity Database

    Nešporová, K.; Sogorková, J.; Smejkalova, D.; Kulhánek, J.; Huerta-Angeles, G.; Kubala, Lukáš; Velebný, V.

    2016-01-01

    Roč. 511, č. 1 (2016), s. 638-647 ISSN 0378-5173 Institutional support: RVO:68081707 Keywords : Polymeric micelle * Hyaluronan * Fatty acid Subject RIV: BO - Biophysics Impact factor: 3.649, year: 2016

  18. Kappa-casein micelles: structure, interaction and gelling studied by small-angle neutron scattering.

    Science.gov (United States)

    de Kruif, C G; May, R P

    1991-09-01

    Small-angle neutron scattering (SANS) measurements on dilute and concentrated dispersions of kappa-casein micelles in a buffer at pH = 6.7 were made using the D11 diffractometer in Grenoble. Results indicate that the micelles have a dense core with a fluffy outer layer. This outer layer appears to give rise to a steeply repulsive interaction on contact. In fact, the hard-sphere model best fits the measured scattering intensities. Adding chymosin to the dispersion initiated a fractal flocculation of the micelles and consecutively a coalescence of the micelles. This unexpected second process resembled that of spinodal demixing. The dispersion phase thus separates into a water and a protein phase on a time scale of hours. The observed phenomona contribute to the understanding of the cheese-making process.

  19. 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.

  20. 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.

  1. 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.

  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. Escape rate of muonium from micelles - as determined by competition kinetics

    International Nuclear Information System (INIS)

    Stadlbauer, J.M.; Venkateswaran, K.; Porter, G.B.; Walker, D.C.

    1994-01-01

    A competition was established for the reaction of muonium atoms (Mu) between nitrate ions in water and benzene or styrene solubilized in micelles. The nitrate was 3.3 - times more efficient at inhibiting muonated free radical formation with benzene than with styrene as the radical-producing solute. Kinetic analysis of this system indicates that Mu emerges from micelles, on average, at least three times during its short (ns) lifetime, these being medium sized micelles carrying on average 3 benzene molecules. So Mu is certainly not trapped, nor even localized. Its escape rate is estimated to be ∼9x10 8 s -1 , which is commensurate with an ordinary diffusion time. The results were obtained by determining the yield of muonated free radicals formed within the micelles using muon-level-crossing-resonance spectroscopy. (orig.)

  4. Removal of Cr(VI) from Aqueous Environments Using Micelle-Clay Adsorption

    Science.gov (United States)

    Qurie, Mohannad; Khamis, Mustafa; Manassra, Adnan; Ayyad, Ibrahim; Nir, Shlomo; Scrano, Laura; Bufo, Sabino A.; Karaman, Rafik

    2013-01-01

    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. PMID:24222757

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-08-01

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

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

    International Nuclear Information System (INIS)

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

    2004-01-01

    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, o-toluidine hydrochloride and m-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. (author)

  7. Micelle Formation of Diblock Copolymers in Thin Film Homopolymers and Homopolymer Blends

    Science.gov (United States)

    Chen, Chelsea; Green, Peter

    2010-03-01

    A-b-B diblock copolymers, at very small concentrations, form micelles in a melt of homopolymer chains of type A or B. In the bulk, the critical micelle concentration, φcmc, is a function of the symmetry of the copolymer chain and exhibits a strong dependence on χN, where χ is the interaction parameter and N is the degree of polymerization of the copolymer. We examined micelle formation in thin film mixtures of: (1) polystyrene-b-poly(2-vinylpyridine) (PS-b-PVP)/polystyrene (PS); (2) PS-b-PVP/ blend of PS and tetramethyl bisphenol-A polycarbonate (TMPC); and (3) polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA)/PS. The critical micelle concentration is found to be orders of magnitude larger than the bulk; it is a strong function of film thickness, the substrate/chain segment interactions and the interactions between the different polymeric segments in the system.

  8. Micelle formation during extraction of alkali elements from strongly alkaline mediums

    International Nuclear Information System (INIS)

    Apanasenko, V.V.; Reznik, A.M.; Bukin, V.I.; Brodskaya, A.V.

    1988-01-01

    Extraction of potassium, rubidium and cesium by phenol reagents in hydrocarbon solvents from strongly alkakine solutions was considered. Tendency of prepared alkali metal phenolates to form micelles in aqueous and organic phases was revealed. Phenolates tendency to form micelles is dictated mainly by the size and position of hydrocarbon substituent in molecule. It is shown that when micelles form in organic phase, alkali elements can be extracted both according to cation-exchange mechanism and according to micellar one. It is noted that alkai element extraction from strongly alkaline media requires the correct choice of extractant: alkali metal phenolate shouldn't form micelles in aqueous solution. n-Alkyl- and arylphenoldisulfides and polysulfides are most preferable for solvent extraction among considered phenol derivatives

  9. 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.

  10. 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.

  11. Ionically conducting Er3+-doped DNA-based biomembranes for electrochromic devices

    International Nuclear Information System (INIS)

    Leones, R.; Fernandes, M.; Sentanin, F.; Cesarino, I.; Lima, J.F.; Zea Bermudez, V. de; Pawlicka, A.; Magon, C.J.; Donoso, J.P.; Silva, M.M.

    2014-01-01

    Biopolymer-based membranes have particular interest due to their biocompatibility, Biodegradability, easy extraction from natural resources and low cost. The incorporation of Er 3+ ions into natural macromolecule hosts with the purpose of producing highly efficient emitting phosphors is of widespread interest in materials science, due to their important roles in display devices. Thus, biomembranes may be viewed as innovative materials for the area of optics. This paper describes studies of luminescent material DNA-based membranes doped with erbium triflate and demonstrates that their potential technological applications may be expanded to electrochromic devices. The sample that exhibits the highest ionic conductivity is DNA 10 Er, (1.17 × 10 −5 and 7.76 × 10 −4 S.cm −1 at 30 and 100 °C, respectively). DSC, XRD and POM showed that the inclusion of the guest salt into DNA does not change significantly its amorphous nature. The overall redox stability was ca. 2.0 V indicating that these materials have an acceptable stability window for applications in solid state electrochemical devices. The EPR analysis suggested that the Er 3+ ions are distributed in various environments. A small ECD comprising a Er 3+ -doped DNA-based membrane was assembled and tested by cyclic voltammetry and chronoamperometry. These electrochemical analyses revealed a pale blue color to transparent color change and a decrease of the charge density from -4.0 to -1.2 mC.cm −2 during 4000 color/bleaching cycles

  12. The Five Immune Forces Impacting DNA-Based Cancer Immunotherapeutic Strategy.

    Science.gov (United States)

    Amara, Suneetha; Tiriveedhi, Venkataswarup

    2017-03-17

    DNA-based vaccine strategy is increasingly realized as a viable cancer treatment approach. Strategies to enhance immunogenicity utilizing tumor associated antigens have been investigated in several pre-clinical and clinical studies. The promising outcomes of these studies have suggested that DNA-based vaccines induce potent T-cell effector responses and at the same time cause only minimal side-effects to cancer patients. However, the immune evasive tumor microenvironment is still an important hindrance to a long-term vaccine success. Several options are currently under various stages of study to overcome immune inhibitory effect in tumor microenvironment. Some of these approaches include, but are not limited to, identification of neoantigens, mutanome studies, designing fusion plasmids, vaccine adjuvant modifications, and co-treatment with immune-checkpoint inhibitors. In this review, we follow a Porter's analysis analogy, otherwise commonly used in business models, to analyze various immune-forces that determine the potential success and sustainable positive outcomes following DNA vaccination using non-viral tumor associated antigens in treatment against cancer.

  13. Copper-Nitrogen-Doped Graphene Hybrid as an Electrochemical Sensing Platform for Distinguishing DNA Bases.

    Science.gov (United States)

    Sun, Shu-Wen; Liu, Hai-Ling; Zhou, Yue; Wang, Feng-Bin; Xia, Xing-Hua

    2017-10-17

    An electrochemical sensor using ultralight and porous copper-nitrogen-doped graphene (CuNRGO) nanocomposite as the electrocatalyst has been constructed to simultaneously determine DNA bases such as guanine (G) and cytosine (C), adenine (A), and thymine (T). The nanocomposite is synthesized by thermally annealing an ice-templated structure of graphene oxide (GO) and Cu(phen) 2 . Because of the unique structure and the presence of Cu 2+ -N active sites, the CuNRGO exhibits outstanding electrocatalytic activity toward the oxidation of free DNA bases. After optimizing the experimental conditions, the CuNRGO-based electrochemical sensor shows good linear responses for the G, A, T, and C bases in the concentration ranges of 0.132-6.62 μM, 0.37-5.18 μM, 198.2-5551 μM, and 270.0-1575 μM, respectively. The results demonstrate that CuNRGO is a promising electrocatalyst for electrochemical sensing devices.

  14. The application of a DNA-based identification technique to over-the-counter herbal medicines.

    Science.gov (United States)

    Kazi, Tazimuddin; Hussain, Nazreen; Bremner, Paul; Slater, Adrian; Howard, Caroline

    2013-06-01

    Reliable methods to identify medicinal plant material are becoming more important in an increasingly regulated market place. DNA-based methods have been recognised as a valuable tool in this area with benefits such as being unaffected by the age of the plant material, growth conditions and harvesting techniques. It is possible that the methods of production used for medicinal plant products will degrade or remove DNA. So how applicable are these techniques to processed medicinal plant products? A simple PCR-based identification technique has been developed for St. John's Wort, Hypericum perforatum L. Thirteen St. John's Wort products were purchased including capsules, tablets and tinctures. DNA was extracted from each product, and the species specific PCR test conducted. DNA was successfully extracted from all thirteen products, using a fast and efficient modified method for extracting DNA from tinctures. Only four products yielded the full length ITS region (850 bp) due to the quality of the DNA. All of the products tested positive for H. perforatum DNA. DNA-based identification methods can complement existing methods of authentication. This paper shows that these methods are applicable to a wide range of processed products, provided that they are designed to account for the possibility of DNA degradation. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. DNA-based stable isotope probing: a link between community structure and function

    International Nuclear Information System (INIS)

    Uhlik, Ondrej; Jecna, Katerina; Leigh, Mary Beth; Mackova, Martina; Macek, Tomas

    2009-01-01

    DNA-based molecular techniques permit the comprehensive determination of microbial diversity but generally do not reveal the relationship between the identity and the function of microorganisms. The first direct molecular technique to enable the linkage of phylogeny with function is DNA-based stable isotope probing (DNA-SIP). Applying this method first helped describe the utilization of simple compounds, such as methane, methanol or glucose and has since been used to detect microbial communities active in the utilization of a wide variety of compounds, including various xenobiotics. The principle of the method lies in providing 13C-labeled substrate to a microbial community and subsequent analyses of the 13C-DNA isolated from the community. Isopycnic centrifugation permits separating 13C-labeled DNA of organisms that utilized the substrate from 12C-DNA of the inactive majority. As the whole metagenome of active populations is isolated, its follow-up analysis provides successful taxonomic identification as well as the potential for functional gene analyses. Because of its power, DNA-SIP has become one of the leading techniques of microbial ecology research. But from other point of view, it is a labor-intensive method that requires careful attention to detail during each experimental step in order to avoid misinterpretation of results.

  16. The Five Immune Forces Impacting DNA-Based Cancer Immunotherapeutic Strategy

    Directory of Open Access Journals (Sweden)

    Suneetha Amara

    2017-03-01

    Full Text Available DNA-based vaccine strategy is increasingly realized as a viable cancer treatment approach. Strategies to enhance immunogenicity utilizing tumor associated antigens have been investigated in several pre-clinical and clinical studies. The promising outcomes of these studies have suggested that DNA-based vaccines induce potent T-cell effector responses and at the same time cause only minimal side-effects to cancer patients. However, the immune evasive tumor microenvironment is still an important hindrance to a long-term vaccine success. Several options are currently under various stages of study to overcome immune inhibitory effect in tumor microenvironment. Some of these approaches include, but are not limited to, identification of neoantigens, mutanome studies, designing fusion plasmids, vaccine adjuvant modifications, and co-treatment with immune-checkpoint inhibitors. In this review, we follow a Porter’s analysis analogy, otherwise commonly used in business models, to analyze various immune-forces that determine the potential success and sustainable positive outcomes following DNA vaccination using non-viral tumor associated antigens in treatment against cancer.

  17. DNA-Based Identification of Forensically Important Blow Flies (Diptera: Calliphoridae) From India.

    Science.gov (United States)

    Bharti, Meenakshi; Singh, Baneshwar

    2017-09-01

    Correct species identification is the first and the most important criteria in entomological evidence-based postmortem interval (PMI) estimation. Although morphological keys are available for species identification of adult blow flies, keys for immature stages are either lacking or are incomplete. In this study, cytochrome oxidase subunit 1 (COI) reference data were developed from nine species (belonging to three subfamilies, namely, Calliphorinae, Luciliinae, and Chrysomyinae) of blow flies from India. Seven of the nine species included in this study were found suitable for DNA-based identification using COI gene, because they showed nonoverlapping intra- (0.0-0.3%) and inter-(1.96-18.14%) specific diversity, and formed well-supported monophyletic clade in phylogenetic analysis. The remaining two species (i.e., Chrysomya megacephala (Fabricius) and Chrysomya chani Kurahashi) cannot be distinguished reliably using our database because they had a very low interspecific diversity (0.11%), and Ch. megacephala was paraphyletic with respect to Ch. chani in the phylogenetic analysis. We conclude that the COI gene is a useful marker for DNA-based identification of blow flies from India. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Density functional MO calculation for stacked DNA base-pairs with backbones.

    Science.gov (United States)

    Kurita, N; Kobayashi, K

    2000-05-01

    In order to elucidate the effect of the sugar and phosphate backbones on the stable structure and electronic properties of stacked DNA base-pairs, we performed ab initio molecular orbital (MO) calculations based on the density functional theory and Slater-type basis set. As a model cluster for stacked base-pairs, we employed three isomers for the dimer unit of stacked guanine-cytosine pairs composed with backbones as well as base-pairs. These structures were fully optimized and their electronic properties were self-consistently investigated. By including the backbones, the difference in total energy among the isomers was largely enhanced, while the trend in relative stability was not changed. The effect of backbones on the electronic properties is remarkable: the MOs with the character of the PO4 parts of backbones appear just below the highest-occupied MO. This result indicates that the PO4 parts might play a rule as a reaction site in chemical processes concerning DNA. Therefore, we conclude that the DNA backbones are indispensable for investigating the stability and electronic properties of the stacked DNA base-pairs.

  19. Augmentation of French grunt diet description using combined visual and DNA-based analyses

    Science.gov (United States)

    Hargrove, John S.; Parkyn, Daryl C.; Murie, Debra J.; Demopoulos, Amanda W.J.; Austin, James D.

    2012-01-01

    Trophic linkages within a coral-reef ecosystem may be difficult to discern in fish species that reside on, but do not forage on, coral reefs. Furthermore, dietary analysis of fish can be difficult in situations where prey is thoroughly macerated, resulting in many visually unrecognisable food items. The present study examined whether the inclusion of a DNA-based method could improve the identification of prey consumed by French grunt, Haemulon flavolineatum, a reef fish that possesses pharyngeal teeth and forages on soft-bodied prey items. Visual analysis indicated that crustaceans were most abundant numerically (38.9%), followed by sipunculans (31.0%) and polychaete worms (5.2%), with a substantial number of unidentified prey (12.7%). For the subset of prey with both visual and molecular data, there was a marked reduction in the number of unidentified sipunculans (visual – 31.1%, combined &ndash 4.4%), unidentified crustaceans (visual &ndash 15.6%, combined &ndash 6.7%), and unidentified taxa (visual &ndash 11.1%, combined &ndash 0.0%). Utilising results from both methodologies resulted in an increased number of prey placed at the family level (visual &ndash 6, combined &ndash 33) and species level (visual &ndash 0, combined &ndash 4). Although more costly than visual analysis alone, our study demonstrated the feasibility of DNA-based identification of visually unidentifiable prey in the stomach contents of fish.

  20. Structuring polymers for delivery of DNA-based therapeutics: updated insights.

    Science.gov (United States)

    Gupta, Madhu; Tiwari, Shailja; Vyas, Suresh

    2012-01-01

    Gene therapy offers greater opportunities for treating numerous incurable diseases from genetic disorders, infections, and cancer. However, development of appropriate delivery systems could be one of the most important factors to overcome numerous biological barriers for delivery of various therapeutic molecules. A number of nonviral polymer-mediated vectors have been developed for DNA delivery and offer the potential to surmount the associated problems of their viral counterpart. To address the concerns associated with safety issues, a wide range of polymeric vectors are available and have been utilized successfully to deliver their therapeutics in vivo. Today's research is mainly focused on the various natural or synthetic polymer-based delivery carriers that protect the DNA molecule from degradation, which offer specific targeting to the desired cells after systemic administration, have transfection efficiencies equivalent to virus-mediated gene delivery, and have long-term gene expression through sustained-release mechanisms. This review explores an updated overview of different nonviral polymeric delivery system for delivery of DNA-based therapeutics. These polymeric carriers have been evaluated in vitro and in vivo and are being utilized in various stages of clinical evaluation. Continued research and understanding of the principles of polymer-based gene delivery systems will enable us to develop new and efficient delivery systems for the delivery of DNA-based therapeutics to achieve the goal of efficacious and specific gene therapy for a vast array of clinical disorders as the therapeutic solutions of tomorrow.

  1. Glucose-installed, SPIO-loaded PEG- b-PCL micelles as MR contrast agents to target prostate cancer cells

    Science.gov (United States)

    Theerasilp, Man; Sunintaboon, Panya; Sungkarat, Witaya; Nasongkla, Norased

    2017-11-01

    Polymeric micelles of poly(ethylene glycol)- block-poly(ɛ-caprolactone) bearing glucose analog encapsulated with superparamagnetic iron oxide nanoparticles (Glu-SPIO micelles) were synthesized as an MRI contrast agent to target cancer cells based on high-glucose metabolism. Compared to SPIO micelles (non-targeting SPIO micelles), Glu-SPIO micelles demonstrated higher toxicity to human prostate cancer cell lines (PC-3) at high concentration. Atomic absorption spectroscopy was used to determine the amount of iron in cells. It was found that the iron in cancer cells treated by Glu-SPIO micelles were 27-fold higher than cancer cells treated by SPIO micelles at the iron concentration of 25 ppm and fivefold at the iron concentration of 100 ppm. To implement Glu-SPIO micelles as a MR contrast agent, the 3-T clinical MRI was applied to determine transverse relaxivities ( r 2*) and relaxation rate (1/ T 2*) values. In vitro MRI showed different MRI signal from cancer cells after cellular uptake of SPIO micelles and Glu-SPIO micelles. Glu-SPIO micelles was highly sensitive with the r 2* in agarose gel at 155 mM-1 s-1. Moreover, the higher 1/ T 2* value was found for cancer cells treated with Glu-SPIO micelles. These results supported that glucose ligand increased the cellular uptake of micelles by PC-3 cells with over-expressing glucose transporter on the cell membrane. Thus, glucose can be used as a small molecule ligand for targeting prostate cancer cells overexpressing glucose transporter.

  2. Vitamin E succinate-conjugated F68 micelles for mitoxantrone delivery in enhancing anticancer activity

    Directory of Open Access Journals (Sweden)

    Liu Y

    2016-07-01

    Full Text Available Yuling Liu,1,* Yingqi Xu,2,* Minghui Wu,3 Lijiao Fan,1 Chengwei He,2 Jian-Bo Wan,2 Peng Li,2 Meiwan Chen,2 Hui Li11Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, People’s Republic of China; 2State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau, People’s Republic of China; 3Department of Cell Biology and Anatomy, School of Medicine, University of Florida, Gainesville, FL, USA *These authors contributed equally to this work Abstract: Mitoxantrone (MIT is a chemotherapeutic agent with promising anticancer efficacy. In this study, Pluronic F68-vitamine E succinate (F68-VES amphiphilic polymer micelles were developed for delivering MIT and enhancing its anticancer activity. MIT-loaded F68–VES (F68–VES/MIT micelles were prepared via the solvent evaporation method with self-assembly under aqueous conditions. F68–VES/MIT micelles were found to be of optimal particle size with the narrow size distribution. Transmission electron microscopy images of F68–VES/MIT micelles showed homogeneous spherical shapes and smooth surfaces. F68–VES micelles had a low critical micelle concentration value of 3.311 mg/L, as well as high encapsulation efficiency and drug loading. Moreover, F68–VES/MIT micelles were stable in the presence of fetal bovine serum for 24 hours and maintained sustained drug release in vitro. Remarkably, the half maximal inhibitory concentration (IC50 value of F68–VES/MIT micelles was lower than that of free MIT in both MDA-MB-231 and MCF-7 cells (two human breast cancer cell lines. In addition, compared with free MIT, there was an increased trend of apoptosis and cellular uptake of F68–VES/MIT micelles in MDA-MB-231 cells. Taken together, these results indicated that F68–VES polymer micelles were able to effectively deliver MIT and largely improve its potency in cancer therapy. Keywords: F68, vitamin E

  3. Therapeutic and scintigraphic applications of polymeric micelles: combination of chemotherapy and radiotherapy in hepatocellular carcinoma

    Directory of Open Access Journals (Sweden)

    Shih YH

    2015-12-01

    Full Text Available Ying-Hsia Shih,1,2 Cheng-Liang Peng,2 Ping-Fang Chiang,1,2 Wuu-Jyh Lin,2 Tsai-Yueh Luo,2,3 Ming-Jium Shieh1,4 1Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan; 2Isotope Application Division, Institute of Nuclear Energy Research, Taoyuan, Taiwan; 3Institute of Radiological Science, Central University, Taichung, Taiwan; 4Department of Oncology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan Abstract: This study evaluated a multifunctional micelle simultaneously loaded with doxorubicin (Dox and labeled with radionuclide rhenium-188 (188Re as a combined radiotherapy and chemotherapy treatment for hepatocellular carcinoma. We investigated the single photon emission computed tomography, biodistribution, antitumor efficacy, and pathology of 188Re-Dox micelles in a murine orthotopic luciferase-transfected BNL tumor cells hepatocellular carcinoma model. The single photon emission computed tomography and computed tomography images showed high radioactivity in the liver and tumor, which was in agreement with the biodistribution measured by γ-counting. In vivo bioluminescence images showed the smallest size tumor (P<0.05 in mice treated with the combined micelles throughout the experimental period. In addition, the combined 188Re-Dox micelles group had significantly longer survival compared with the control, 188ReO4 alone (P<0.005, and Dox micelles alone (P<0.01 groups. Pathohistological analysis revealed that tumors treated with 188Re-Dox micelles had more necrotic features and decreased cell proliferation. Therefore, 188Re-Dox micelles may enable combined radiotherapy and chemotherapy to maximize the effectiveness of treatment for hepatocellular carcinoma. Keywords: 188Re-Dox micelles, radiotherapeutic, chemotherapeutic, hepatocellular carcinoma

  4. Andrographolide-loaded PLGA-PEG-PLGA micelles to improve its bioavailability and anticancer efficacy.

    Science.gov (United States)

    Zhang, Jinming; Li, Yingbo; Gao, Wei; Repka, Michael A; Wang, Yitao; Chen, Meiwan

    2014-09-01

    Andrographolide (ADG) isolated from Andrographis paniculata exhibits anti-inflammatory and anticancer activities, but high hydrophobicity and poor bioavailability greatly restricts its clinical application. In this study, ADG was encapsulated in a micelle formulation based on poly (D,L-lactide-co-glycolide)-b-poly (ethylene glycol)-b-poly (D,L-lactide-co-glycolide) (PLGA-PEG-PLGA) amphiphilic triblock copolymers, in order to enhance the anticancer efficacy and bioavailability in vivo. The physicochemical properties of the ADG-loaded PLGA-PEG-PLGA micelles were investigated for encapsulation efficiency, particle size, zeta potential and critical micelle concentration. These micelles were further evaluated for in vitro cytotoxicity, including proliferation inhibition, cell cycle arrest and pro-apoptosis effects against human breast cancer MAD-MB-231 cells, cellular uptake and pharmacokinetics study in rat. ADG-loaded PLGA-PEG-PLGA micelles had a high encapsulation and loading efficiency of about 92 and 8.4% (w/w), respectively, and a stable particle size of 124.3 ± 6.4 nm. In vitro cytotoxicity testing demonstrated that ADG-loaded PLGA-PEG-PLGA micelles exhibited higher proliferation inhibition, cell cycle arrest at the G2/M phase and pro-apoptosis effects in MAD-MB-231 cells, which would be contributed to higher efficiency of cellular uptake and intracellular transport. Further, the plasma AUC(0 - ∞) and mean resident time of ADG-loaded PLGA-PEG-PLGA micelles were increased by 2.7- and 2.5-fold, respectively, when compared to the raw suspension. All of these investigations suggest that PLGA-PEG-PLGA micelles may be a potential drug delivery strategy for improving ADG bioavailability and efficacy in cancer therapy.

  5. Patchy micelles based on coassembly of block copolymer chains and block copolymer brushes on silica particles.

    Science.gov (United States)

    Zhu, Shuzhe; Li, Zhan-Wei; Zhao, Hanying

    2015-04-14

    Patchy particles are a type of colloidal particles with one or more well-defined patches on the surfaces. The patchy particles with multiple compositions and functionalities have found wide applications from the fundamental studies to practical uses. In this research patchy micelles with thiol groups in the patches were prepared based on coassembly of free block copolymer chains and block copolymer brushes on silica particles. Thiol-terminated and cyanoisopropyl-capped polystyrene-block-poly(N-isopropylacrylamide) block copolymers (PS-b-PNIPAM-SH and PS-b-PNIPAM-CIP) were synthesized by reversible addition-fragmentation chain transfer polymerization and chemical modifications. Pyridyl disulfide-functionalized silica particles (SiO2-SS-Py) were prepared by four-step surface chemical reactions. PS-b-PNIPAM brushes on silica particles were prepared by thiol-disulfide exchange reaction between PS-b-PNIPAM-SH and SiO2-SS-Py. Surface micelles on silica particles were prepared by coassembly of PS-b-PNIPAM-CIP and block copolymer brushes. Upon cleavage of the surface micelles from silica particles, patchy micelles with thiol groups in the patches were obtained. Dynamic light scattering, transmission electron microscopy, and zeta-potential measurements demonstrate the preparation of patchy micelles. Gold nanoparticles can be anchored onto the patchy micelles through S-Au bonds, and asymmetric hybrid structures are formed. The thiol groups can be oxidized to disulfides, which results in directional assembly of the patchy micelles. The self-assembly behavior of the patchy micelles was studied experimentally and by computer simulation.

  6. 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.

  7. 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

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  9. Light-responsive micelles of spiropyran initiated hyperbranched polyglycerol for smart drug delivery.

    Science.gov (United States)

    Son, Suhyun; Shin, Eeseul; Kim, Byeong-Su

    2014-02-10

    Light-responsive polymeric micelles have emerged as site-specific and time-controlled systems for advanced drug delivery. Spiropyran (SP), a well-known photochromic molecule, was used to initiate the ring-opening multibranching polymerization of glycidol to afford a series of hyperbranched polyglycerols (SP-hb-PG). The micelle assembly and disassembly were induced by an external light source owing to the reversible photoisomerization of hydrophobic SP to hydrophilic merocyanine (MC). Transmission electron microscopy, atomic force microscopy, UV/vis spectroscopy, and dynamic light scattering demonstrated the successful assembly and disassembly of SP-hb-PG micelles. In addition, the critical micelle concentration (CMC) was determined through the fluorescence analysis of pyrene to confirm the amphiphilicity of respective SP-hb-PGn (n = 15, 29, and 36) micelles, with CMC values ranging from 13 to 20 mg/L, which is correlated to the length of the polar polyglycerol backbone. Moreover, the superior biocompatibility of the prepared SP-hb-PG was evaluated using WI-38 cells and HeLa cells, suggesting the prospective applicability of the micelles in smart drug delivery systems.

  10. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Capillary electrophoresis study on phase of mixed micelles and its role in transport phenomena of particles.

    Science.gov (United States)

    Oszwałdowski, Sławomir; Kubáň, Pavel

    2015-03-15

    In the present work comprehensive studies on electrophoretic effects induced by a phase of mixed micelles, that migrates surrounded with background electrolyte (BGE) and is denoted as the BGE/segment of mixed micelles/BGE system, were undertaken using capillary electrophoresis coupled with contactless conductivity or UV-vis detector. It was established that mixed micelles under electrophoresis are subject of evolution in terms of mobility, peak area and presence of sub-zones enforced by the composition of micellar phase, segment length and applied voltage. Established features allowed us to explain the electrophoretic behavior of nanoparticles in the system BGE/sample containing nanocrystals/segment of mixed micelles/BGE and it was postulated that a pseudomicellar state of nanoparticles can be useful term in analyzing the migration phenomena of nanoparticles within micellar environment. In contrast to the previous works, where transport of nanocrystals (NCs) within micellar segment or between two micellar segments was analyzed, the present work is focused on the transport of NCs from sample of NCs dispersed in BGE to phase of mixed micelles, i.e., to rear boundary between micellar zone and BGE. Based on these results, systematic studies on transport efficiency for nanoparticles in the system BGE/sample containing nanocrystals/segment of mixed micelles/BGE show that the system assures efficient transport of nanoparticles from BGE based sample to micellar phase and their efficient preconcentration at the micellar segment/BGE rear boundary. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Synthesis of CaCO3 nanoparticles by carbonation of lime solutions in reverse micellar systems

    NARCIS (Netherlands)

    Heeres, H.J.; Jain, R.; Mehra, A.; Dagaonkar, M.V.

    2004-01-01

    Application of reverse micelles for the synthesis of nano-sized calcium carbonate particles in different solvents (cyclohexane, decane and heptane) has been investigated. The effect of the mole ratio of water-to-surfactant (R) and type of solvent has been studied on the size and nature of the

  13. SYNTHESIS AND PHYSICAL-PROPERTIES OF HIGHLY CA2+- TOLERANT DISODIUM 2-(SULFATOMETHYL)-1-ALKYLSULFATE SURFACTANTS

    NARCIS (Netherlands)

    Kooreman, P A; Engberts, J B F N

    The synthesis, critical micelle concentrations (CMC) and Krafft temperatures (T(Krafft)) of a series of disodium 2-(sulfatomethyl)-1-alkylsulfates (2a-d) are presented, with alkyl being n-tetradecyl (C-14), n-hexadecyl (C-16), n-octadecyl (C18) and n-eicosyl(C20). The surfactants exhibit a large

  14. Synthesis and catalytic properties of metal and semiconductor nanoclusters

    Science.gov (United States)

    Wilcoxon, J. P.; Martino, T.; Klavetter, E.; Sylwester, A. P.

    Synthesis of metal or semiconductor nanoclusters in microheterogeneous oil-continuous inverse micelle systems is discussed. We focus on synthesis and catalytic properties of palladium, iron, and iron sulfide nanoclusters. Cluster size-control is achieved by changing the micelle size which is determined by small angle neutron scattering (SANS) and chosen to produce cluster in size range of 1-20 nm. Cluster sizes were determined by either transmission electron microscopy (TEM) or small-angle x-ray scattering (SAXS). Cluster structure was determined by either x-ray or electron diffraction. In the case of Fe nanoclusters, the crystal structure depended on the chemical nature of the surfactant micelle used in the synthesis, illustrating the important role of the surfactant during the growth process. Results of in-situ pyrene hydrogenation using size-selected Pd clusters show a significant increase in activity/total surface area as the size decreases. These clusters also proved effective as unsupported catalysts for direct coal hydropyrolysis, even at very low metal concentrations. Synthesis and optical features of a new semiconductor cluster material, FeS2, are discussed with regard to its use in photocatalysis. Application of FeS2 in coal hydrogenolysis reactions has improved yields of short chain hydrocarbons significantly compared to conventional FeS2 powders.

  15. Polymeric Micelles for Delivery of Poorly Soluble Drugs: Preparation and Anticancer Activity In Vitro of Paclitaxel Incorporated into Mixed Micelles Based on Poly(ethylene Glycol)-Lipid Conjugate and Positively Charged Lipids

    Science.gov (United States)

    WANG, JUNPING; MONGAYT, DIMITRY; TORCHILIN, VLADIMIR P.

    2006-01-01

    Paclitaxel-loaded mixed polymeric micelles consisting of poly(ethylene glycol)-distearoyl phosphoethanolamine conjugates (PEG-PE), solid triglycerides (ST), and cationic Lipofectin® lipids (LL) have been prepared. Micelles with the optimized composition (PEG-PE/ST/LL/paclitaxel = 12/12/2/1 by weight) had an average micelle size of about 100 nm, and zeta-potential of about 26 mV. Micelles were stable and did not release paclitaxel when stored at 4°C in the darkness (just 2.9% of paclitaxel have been lost after 4 months with the particle size remaining unchanged). The release of paclitaxel from such micelles at room temperature was also insignificant. However, at 37°C, approx. 16% of paclitaxel was released from PEG-PE/ST/LL/paclitaxel micelles in 72 h, probably, because of phase transition in the ST-containing micelle core. In vitro anticancer effects of PEG-PE/ST/LL/paclitaxel and control micelles were evaluated using human mammary adenocarcinoma (BT-20) and human ovarian carcinoma (A2780) cell lines. Paclitaxel in PEG-PE/ST/LL micelles demonstrated the maximum anti-cancer activity. Cellular uptake of fluorescently-labeled paclitaxel-containing micelles by BT-20 cells was investigated using a fluorescence microscopy. It seems that PEG-PE/ST/LL micelles, unlike micelles without the LL component, could escape from endosomes and enter the cytoplasm of BT-20 cancer cells thus increasing the anticancer efficiency of the micellar paclitaxel. PMID:15848957

  16. DNA-based nanobiostructured devices: The role of quasiperiodicity and correlation effects

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, E.L., E-mail: eudenilson@gmail.com [Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal-RN (Brazil); Fulco, U.L. [Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal-RN (Brazil); Freire, V.N. [Departamento de Física, Universidade Federal do Ceará, 60455-760, Fortaleza-CE (Brazil); Caetano, E.W.S. [Instituto Federal de Educação, Ciência e Tecnologia do Ceará, 60040-531, Fortaleza-CE (Brazil); Lyra, M.L.; Moura, F.A.B.F. de [Instituto de Física, Universidade Federal de Alagoas, 57072-970, Maceió-AL (Brazil)

    2014-02-01

    The purpose of this review is to present a comprehensive and up-to-date account of the main physical properties of DNA-based nanobiostructured devices, stressing the role played by their quasi-periodicity arrangement and correlation effects. Although the DNA-like molecule is usually described as a short-ranged correlated random ladder, artificial segments can be grown following quasiperiodic sequences as, for instance, the Fibonacci and Rudin–Shapiro ones. They have interesting properties like a complex fractal spectra of energy, which can be considered as their indelible mark, and collective properties that are not shared by their constituents. These collective properties are due to the presence of long-range correlations, which are expected to be reflected somehow in their various spectra (electronic transmission, density of states, etc.) defining another description of disorder. Although long-range correlations are responsible for the effective electronic transport at specific resonant energies of finite DNA segments, much of the anomalous spread of an initially localized electron wave-packet can be accounted by short-range pair correlations, suggesting that an approach based on the inclusion of further short-range correlations on the nucleotide distribution leads to an adequate description of the electronic properties of DNA segments. The introduction of defects may generate states within the gap, and substantially improves the conductance, specially of finite branches. They usually become exponentially localized for any amount of disorder, and have the property to tailor the electronic transport properties of DNA-based nanoelectronic devices. In particular, symmetric and antisymmetric correlations have quite distinct influence on the nature of the electronic states, and a diluted distribution of defects lead to an anomalous diffusion of the electronic wave-packet. Nonlinear contributions, arising from the coupling between electrons and the molecular

  17. DNA micelle flares: a study of the basic properties that contribute to enhanced stability and binding affinity in complex biological systems.

    Science.gov (United States)

    Wang, Yanyue; Wu, Cuichen; Chen, Tao; Sun, Hao; Cansiz, Sena; Zhang, Liqin; Cui, Cheng; Hou, Weijia; Wu, Yuan; Wan, Shuo; Cai, Ren; Liu, Yuan; Sumerlin, Brent; Zhang, Xiaobing; Tan, Weihong

    2016-01-01

    DMFs are spherical DNA-diacyllipid nanostructures formed by hydrophobic effects between lipid tails coupled to single-stranded DNAs. Such properties as high cellular permeability, low critical micelle concentration (CMC) and facile fabrication facilitate intracellular imaging and drug delivery. While the basic properties of NFs have been amply described and tested, few studies have characterized the fundamental properties of DMFs with particular respect to aggregation number, dissociation constant and biostability. Therefore, to further explore their conformational features and enhanced stability in complex biological systems, we herein report a series of characterization studies. Static light scattering (SLS) demonstrated that DMFs possess greater DNA loading capacity when compared to other DNA-based nanostructures. Upon binding to complementary DNA (cDNA), DMFs showed excellent dissociation constants (K d ) and increased melting temperatures, as well as constant CMC (10 nM) independent of DNA length. DMFs also present significantly enhanced stability in aqueous solution with nuclease and cell lysate. These properties make DMFs ideal for versatile applications in bioanalysis and theranostics studies.

  18. DNA-Based Single-Molecule Electronics: From Concept to Function

    Science.gov (United States)

    2018-01-01

    Beyond being the repository of genetic information, DNA is playing an increasingly important role as a building block for molecular electronics. Its inherent structural and molecular recognition properties render it a leading candidate for molecular electronics applications. The structural stability, diversity and programmability of DNA provide overwhelming freedom for the design and fabrication of molecular-scale devices. In the past two decades DNA has therefore attracted inordinate amounts of attention in molecular electronics. This review gives a brief survey of recent experimental progress in DNA-based single-molecule electronics with special focus on single-molecule conductance and I–V characteristics of individual DNA molecules. Existing challenges and exciting future opportunities are also discussed. PMID:29342091

  19. Refined Exercise testing can aid DNA-based Diagnosis in Muscle Channelopathies

    Science.gov (United States)

    Tan, S. Veronica; Matthews, Emma; Barber, Melissa; Burge, James A; Rajakulendran, Sanjeev; Fialho, Doreen; Sud, Richa; Haworth, Andrea; Koltzenburg, Martin; Hanna, Michael G

    2010-01-01

    Objective To improve the accuracy of genotype prediction and guide genetic testing in patients with muscle channelopathies we applied and refined specialised electrophysiological exercise test parameters. Methods We studied 56 genetically confirmed patients and 65 controls using needle electromyography, the long exercise test, and short exercise tests at room temperature, after cooling, and rewarming. Results Concordant amplitude-and-area decrements were more reliable than amplitude-only measurements when interpreting patterns of change during the short exercise tests. Concordant amplitude-and-area pattern I and pattern II decrements of >20% were 100% specific for PMC and MC respectively. When decrements at room temperature and after cooling were 20% allow more reliable interpretation of the short exercise tests and aid accurate DNA-based diagnosis. In patients with negative exercise tests, specific clinical features are helpful in differentiating sodium from chloride channel myotonia. A modified algorithm is suggested.. PMID:21387378

  20. Recent advances in DNA-based electrochemical biosensors for heavy metal ion detection: A review.

    Science.gov (United States)

    Saidur, M R; Aziz, A R Abdul; Basirun, W J

    2017-04-15

    The presence of heavy metal in food chains due to the rapid industrialization poses a serious threat on the environment. Therefore, detection and monitoring of heavy metals contamination are gaining more attention nowadays. However, the current analytical methods (based on spectroscopy) for the detection of heavy metal contamination are often very expensive, tedious and can only be handled by trained personnel. DNA biosensors, which are based on electrochemical transduction, is a sensitive but inexpensive method of detection. The principles, sensitivity, selectivity and challenges of electrochemical biosensors are discussed in this review. This review also highlights the major advances of DNA-based electrochemical biosensors for the detection of heavy metal ions such as Hg 2+ , Ag + , Cu 2+ and Pb 2+ . Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Development of Randomly Amplified Polymorphic DNA Based SCAR Marker for Identification of Ipomoea mauritiana Jacq (Convolvulaceae

    Directory of Open Access Journals (Sweden)

    Kambiranda Devaiah

    2011-01-01

    Full Text Available Vidari is an Ayurvedic herbal drug used as aphrodisiac, galactagogue and is also used in the preparation of Chyavanaprash. Tubers of Ipomoea mauritiana Jacq. (Convolvulaceae, Pueraria tuberosa (Roxb. ex Willd. DC (Fabaceae, Adenia hondala (Gaertn. de Wilde (Passifloraceae and pith of Cycas circinalis L. (Cycadaceae are all traded in the name of Vidari, creating issues of botanical authenticity of the Ayurvedic raw drug. DNA-based markers have been developed to distinguish I. mauritiana from the other Vidari candidates. A putative 600-bp polymorphic sequence, specific to I. mauritiana was identified using randomly amplified polymorphic DNA (RAPD technique. Furthermore, sequence characterized amplified region (SCAR primers (IM1F and IM1R were designed from the unique RAPD amplicon. The SCAR primers produced a specific 323-bp amplicon in authentic I. mauritiana and not in the allied species.

  2. Development of Randomly Amplified Polymorphic DNA Based SCAR Marker for Identification of Ipomoea mauritiana Jacq (Convolvulaceae)

    Science.gov (United States)

    Devaiah, Kambiranda; Balasubramani, Subramani Paranthaman; Venkatasubramanian, Padma

    2011-01-01

    Vidari is an Ayurvedic herbal drug used as aphrodisiac, galactagogue and is also used in the preparation of Chyavanaprash. Tubers of Ipomoea mauritiana Jacq. (Convolvulaceae), Pueraria tuberosa (Roxb. ex Willd.) DC (Fabaceae), Adenia hondala (Gaertn.) de Wilde (Passifloraceae) and pith of Cycas circinalis L. (Cycadaceae) are all traded in the name of Vidari, creating issues of botanical authenticity of the Ayurvedic raw drug. DNA-based markers have been developed to distinguish I. mauritiana from the other Vidari candidates. A putative 600-bp polymorphic sequence, specific to I. mauritiana was identified using randomly amplified polymorphic DNA (RAPD) technique. Furthermore, sequence characterized amplified region (SCAR) primers (IM1F and IM1R) were designed from the unique RAPD amplicon. The SCAR primers produced a specific 323-bp amplicon in authentic I. mauritiana and not in the allied species. PMID:21738554

  3. A DNA-based molecular motor that can navigate a network of tracks.

    Science.gov (United States)

    Wickham, Shelley F J; Bath, Jonathan; Katsuda, Yousuke; Endo, Masayuki; Hidaka, Kumi; Sugiyama, Hiroshi; Turberfield, Andrew J

    2012-01-22

    Synthetic molecular motors can be fuelled by the hydrolysis or hybridization of DNA. Such motors can move autonomously and programmably, and long-range transport has been observed on linear tracks. It has also been shown that DNA systems can compute. Here, we report a synthetic DNA-based system that integrates long-range transport and information processing. We show that the path of a motor through a network of tracks containing four possible routes can be programmed using instructions that are added externally or carried by the motor itself. When external control is used we find that 87% of the motors follow the correct path, and when internal control is used 71% of the motors follow the correct path. Programmable motion will allow the development of computing networks, molecular systems that can sort and process cargoes according to instructions that they carry, and assembly lines that can be reconfigured dynamically in response to changing demands.

  4. Ab initio Calculations of Electronic Fingerprints of DNA bases on Graphene

    Science.gov (United States)

    Ahmed, Towfiq; Rehr, John J.; Kilina, Svetlana; Das, Tanmoy; Haraldsen, Jason T.; Balatsky, Alexander V.

    2012-02-01

    We have carried out first principles DFT calculations of the electronic local density of states (LDOS) of DNA nucleotide bases (A,C,G,T) adsorbed on graphene using LDA with ultra-soft pseudo-potentials. We have also calculated the longitudinal transmission currents T(E) through graphene nano-pores as an individual DNA base passes through it, using a non-equilibrium Green's function (NEGF) formalism. We observe several dominant base-dependent features in the LDOS and T(E) in an energy range within a few eV of the Fermi level. These features can serve as electronic fingerprints for the identification of individual bases from dI/dV measurements in scanning tunneling spectroscopy (STS) and nano-pore experiments. Thus these electronic signatures can provide an alternative approach to DNA sequencing.

  5. Anionic magnetite nanoparticle conjugated with pyrrolidinyl peptide nucleic acid for DNA base discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Khadsai, Sudarat; Rutnakornpituk, Boonjira [Naresuan University, Department of Chemistry and Center of Excellence in Biomaterials, Faculty of Science (Thailand); Vilaivan, Tirayut [Chulalongkorn University, Department of Chemistry, Organic Synthesis Research Unit, Faculty of Science (Thailand); Nakkuntod, Maliwan [Naresuan University, Department of Biology, Faculty of Science (Thailand); Rutnakornpituk, Metha, E-mail: methar@nu.ac.th [Naresuan University, Department of Chemistry and Center of Excellence in Biomaterials, Faculty of Science (Thailand)

    2016-09-15

    Magnetite nanoparticles (MNPs) were surface modified with anionic poly(N-acryloyl glycine) (PNAG) and streptavidin for specific interaction with biotin-conjugated pyrrolidinyl peptide nucleic acid (PNA). Hydrodynamic size (D{sub h}) of PNAG-grafted MNPs varied from 334 to 496 nm depending on the loading ratio of the MNP to NAG in the reaction. UV–visible and fluorescence spectrophotometries were used to confirm the successful immobilization of streptavidin and PNA on the MNPs. About 291 pmol of the PNA/mg MNP was immobilized on the particle surface. The PNA-functionalized MNPs were effectively used as solid supports to differentiate between fully complementary and non-complementary/single-base mismatch DNA using the PNA probe. These novel anionic MNPs can be efficiently applicable for use as a magnetically guidable support for DNA base discrimination.Graphical Abstract.

  6. Fast parallel DNA-based algorithms for molecular computation: quadratic congruence and factoring integers.

    Science.gov (United States)

    Chang, Weng-Long

    2012-03-01

    Assume that n is a positive integer. If there is an integer such that M (2) ≡ C (mod n), i.e., the congruence has a solution, then C is said to be a quadratic congruence (mod n). If the congruence does not have a solution, then C is said to be a quadratic noncongruence (mod n). The task of solving the problem is central to many important applications, the most obvious being cryptography. In this article, we describe a DNA-based algorithm for solving quadratic congruence and factoring integers. In additional to this novel contribution, we also show the utility of our encoding scheme, and of the algorithm's submodules. We demonstrate how a variety of arithmetic, shifted and comparative operations, namely bitwise and full addition, subtraction, left shifter and comparison perhaps are performed using strands of DNA.

  7. Anionic magnetite nanoparticle conjugated with pyrrolidinyl peptide nucleic acid for DNA base discrimination

    Science.gov (United States)

    Khadsai, Sudarat; Rutnakornpituk, Boonjira; Vilaivan, Tirayut; Nakkuntod, Maliwan; Rutnakornpituk, Metha

    2016-09-01

    Magnetite nanoparticles (MNPs) were surface modified with anionic poly( N-acryloyl glycine) (PNAG) and streptavidin for specific interaction with biotin-conjugated pyrrolidinyl peptide nucleic acid (PNA). Hydrodynamic size ( D h) of PNAG-grafted MNPs varied from 334 to 496 nm depending on the loading ratio of the MNP to NAG in the reaction. UV-visible and fluorescence spectrophotometries were used to confirm the successful immobilization of streptavidin and PNA on the MNPs. About 291 pmol of the PNA/mg MNP was immobilized on the particle surface. The PNA-functionalized MNPs were effectively used as solid supports to differentiate between fully complementary and non-complementary/single-base mismatch DNA using the PNA probe. These novel anionic MNPs can be efficiently applicable for use as a magnetically guidable support for DNA base discrimination.

  8. DNA-Based Characterization and Identification of Arbuscular Mycorrhizal Fungi Species.

    Science.gov (United States)

    Senés-Guerrero, Carolina; Schüßler, Arthur

    2016-01-01

    Arbuscular mycorrhizal fungi (AMF) are obligate symbionts of most land plants. They have great ecological and economic importance as they can improve plant nutrition, plant water supply, soil structure, and plant resistance to pathogens. We describe two approaches for the DNA-based characterization and identification of AMF, which both can be used for single fungal spores, soil, or roots samples and resolve closely related AMF species: (a) Sanger sequencing of a 1.5 kb extended rDNA-barcode from clone libraries, e.g., to characterize AMF isolates, and (b) high throughput 454 GS-FLX+ pyrosequencing of a 0.8 kb rDNA fragment, e.g., for in-field monitoring.

  9. Anionic magnetite nanoparticle conjugated with pyrrolidinyl peptide nucleic acid for DNA base discrimination

    International Nuclear Information System (INIS)

    Khadsai, Sudarat; Rutnakornpituk, Boonjira; Vilaivan, Tirayut; Nakkuntod, Maliwan; Rutnakornpituk, Metha

    2016-01-01

    Magnetite nanoparticles (MNPs) were surface modified with anionic poly(N-acryloyl glycine) (PNAG) and streptavidin for specific interaction with biotin-conjugated pyrrolidinyl peptide nucleic acid (PNA). Hydrodynamic size (D h ) of PNAG-grafted MNPs varied from 334 to 496 nm depending on the loading ratio of the MNP to NAG in the reaction. UV–visible and fluorescence spectrophotometries were used to confirm the successful immobilization of streptavidin and PNA on the MNPs. About 291 pmol of the PNA/mg MNP was immobilized on the particle surface. The PNA-functionalized MNPs were effectively used as solid supports to differentiate between fully complementary and non-complementary/single-base mismatch DNA using the PNA probe. These novel anionic MNPs can be efficiently applicable for use as a magnetically guidable support for DNA base discrimination.Graphical Abstract

  10. Insight into the Interaction between DNA Bases and Defective Graphenes: Covalent or Non-covalent

    Science.gov (United States)

    Xu, Zhenfeng; Meher, Biswa Ranjan; Eustache, Darnashley; Wang, Yixuan

    2013-01-01

    Although some metal clusters and molecules were found to more significantly bind to defective graphenes than to pristine graphenes, exhibiting chemisorptions on defective graphenes, the present investigation shows that the adsorption of DNA bases on mono- and di-vacant defective graphenes does not show much difference from that on pristine graphene, and is still dominantly driven by noncovalent interactions. In the present study the adsorptions of the nucleobases, adenine (A), cytosine (C), guanine, (G), and thymine (T) on pristine and defective graphenes, are fully optimized using a hybrid-meta GGA density functional theory (DFT), M06-2X/6-31G*, and the adsorption energies are then refined with both M06-2X and B97-D/6-311++G**. Graphene is modeled as nano-clusters of C72H24, C71H24, and C70H24 for pristine, mono- and divacant defective graphenes, respectively, supplemented by a few larger ones. The result shows that guanine has the maximum adsorption energy in all of the three adsorption systems; and the sequence of the adsorption strength is G>A>T>C on the pristine and di-vacant graphene and G>T>A>C on the mono-vacant graphene. In addition, the binding energies of the DNA bases with the pristine graphene are less than the corresponding ones with di-vacant defective graphene; however, they are greater than those of mono-vacant graphene with guanine and adenine, while it is dramatic that the binding energies of mono-vacant graphene with thymine and cytosine appear larger than those of pristine graphene. PMID:24215998

  11. Preparation, Characterization and Evaluation of α-Tocopherol Succinate-Modified Dextran Micelles as Potential Drug Carriers

    Directory of Open Access Journals (Sweden)

    Jingmou Yu

    2015-09-01

    Full Text Available In the present study, α-tocopherol succinate (TOS conjugated dextran (Dex-TOS was synthesized and characterized by fourier transform infrared (FT-IR spectroscopy, 1H nuclear magnetic resonance (1H NMR, dynamic light scattering (DLS and fluorescence spectroscopy. Dex-TOS could form nanoscaled micelles in aqueous medium. The critical micelle concentration (CMC is 0.0034 mg/mL. Doxorubicin (Dox was selected as a model drug. Dox-loaded Dex-TOS (Dex-TOS/Dox micelles were prepared by a dialysis method. The size of Dex-TOS/Dox micelles increased from 295 to 325 nm with the Dox-loading content increasing from 4.21% to 8.12%. The Dex-TOS/Dox micelles were almost spherical in shape, as determined by transmission electron microscopy (TEM. In vitro release demonstrated that Dox release from the micelles was in a sustained manner for up to 96 h. The cellular uptake of Dex-TOS/Dox micelles in human nasopharyngeal epidermoid carcinoma (KB cells is an endocytic process determined by confocal laser scanning microscopy (CLSM. Moreover, Dex-TOS/Dox micelles exhibited comparable cytotoxicity in contrast with doxorubicin hydrochloride. These results suggested that Dex-TOS micelles could be a promising carrier for drug delivery.

  12. Drug-conjugated PLA-PEG-PLA copolymers: a novel approach for controlled delivery of hydrophilic drugs by micelle formation.

    Science.gov (United States)

    Danafar, H; Rostamizadeh, K; Davaran, S; Hamidi, M

    2017-12-01

    A conjugate of the antihypertensive drug, lisinopril, with triblock poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA) copolymer was synthesized by the reaction of PLA-PEG-PLA copolymer with lisinopril in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine. The conjugated copolymer was characterized in vitro by hydrogen nuclear magnetic resonance (HNMR), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) techniques. Then, the lisinopril conjugated PLA-PEG-PLA were self-assembled into micelles in aqueous solution. The resulting micelles were characterized further by various techniques such as dynamic light scattering (DLS) and atomic force microscopy (AFM). The results revealed that the micelles formed by the lisinopril-conjugated PLA-PEG-PLA have spherical structure with the average size of 162 nm. The release behavior of conjugated copolymer, micelles and micelles physically loaded by lisinopril were compared in different media. In vitro release study showed that in contrast to physically loaded micelles, the release rate of micelles consisted of the conjugated copolymer was dependent on pH of media where it was higher at lower pH compared to the neutral medium. Another feature of the conjugated micelles was their more sustained release profile compared to the lisinopril-conjugated copolymer and physically loaded micelles.

  13. 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.

  14. Block Copolymer Micelles for Photonic Fluids and Crystals.

    Science.gov (United States)

    Poutanen, Mikko; Guidetti, Giulia; Gröschel, Tina I; Borisov, Oleg V; Vignolini, Silvia; Ikkala, Olli; Gröschel, Andre H

    2018-03-15

    Block copolymer micelles (BCMs) are self-assembled nanoparticles in solution with a collapsed core and a brush-like stabilizing corona typically in the size range of tens of nanometers. Despite being widely studied in various fields of science and technology, their ability to form structural colors at visible wavelength has not received attention, mainly due to the stringent length requirements of photonic lattices. Here, we describe the precision assembly of BCMs with superstretched corona, yet with narrow size distribution to qualify as building blocks for tunable and reversible micellar photonic fluids (MPFs) and micellar photonic crystals (MPCs). The BCMs form free-flowing MPFs with an average interparticle distance of 150-300 nm as defined by electrosteric repulsion arising from the highly charged and stretched corona. Under quiescent conditions, millimeter-sized MPCs with classical FCC lattice grow within the photonic fluid-medium upon refinement of the positional order of the BCMs. We discuss the generic properties of MPCs with special emphasis on surprisingly narrow reflected wavelengths with full width at half-maximum (fwhm) as small as 1 nm. We expect this concept to open a generic and facile way for self-assembled tunable micellar photonic structures.

  15. Different Types of Charged-Inverse Micelles in Nonpolar Media.

    Science.gov (United States)

    Prasad, Manoj; Strubbe, Filip; Beunis, Filip; Neyts, Kristiaan

    2016-06-14

    Over the last few years, the electrodynamics of charged inverse micelles (CIMs) in nonpolar liquids and the generation mechanism and properties of newly generated CIMs have been studied extensively for the model system of polyisobutylene succinimide in dodecane. However, the newly generated CIMs, which accumulate at the electrodes when a continuous voltage is applied, behave differently compared to the regular CIMs present in equilibrium in the absence of a field. In this work, we use transient current measurements to investigate the behavior of the newly generated CIMs when the field is reduced to zero or reversed. We demonstrate that the newly generated CIMs do not participate in the diffuse double layer near the electrode formed by the regular CIMs but form an interface layer at the electrode surface. A fraction of the newly generated negative CIMs can be released from this interface layer when the field there becomes zero. The findings of this study provide a better understanding of fundamental processes in nonpolar liquids and are relevant for applications such as electronic ink displays and liquid toner printing.

  16. Switching of charged inverse micelles in non-polar liquids.

    Science.gov (United States)

    Prasad, Manoj; Beunis, Filip; Neyts, Kristiaan; Strubbe, Filip

    2015-11-15

    The electrodynamics of micellar ions in nonpolar liquids are well understood for the case that a voltage is applied or switched off. In this work, the electrodynamics of charged inverse micelles (CIMs) are studied when the applied voltage is switched to the opposite polarity, which is relevant for applications such as electrophoretic displays and liquid toner printing. Transient current measurements are used to characterize the switching of CIMs formed in a solution of surfactant polyisobutylene succinimide in n-dodecane. For reverse voltages with amplitude below 10V the measurements are in good agreement with a drift and diffusion model, confirming the established understanding of CIMs in nonpolar liquids. When the charge content is high, the reversal current shows a characteristic peak which is explained on the basis of dynamic space-charge effects. However, for reverse voltages larger than 10V, the transient currents are influenced by electrohydrodynamic flow in the liquid causing the CIMs to switch faster than predicted by the model. The occurrence of electrohydrodynamic flow is verified by optical tracking of tracer particles. Also, when the polarizing voltage is applied for longer times, an additional current peak emerges which is due to the accumulation of newly generated charges at the electrodes. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. 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.

  18. Competitive and Synergistic Interactions between Polymer Micelles, Drugs, and Cyclodextrins: The Importance of Drug Solubilization Locus.

    Science.gov (United States)

    Valero, Margarita; Castiglione, Franca; Mele, Andrea; da Silva, Marcelo A; Grillo, Isabelle; González-Gaitano, Gustavo; Dreiss, Cécile A

    2016-12-13

    Polymeric micelles, in particular PEO-PPO-based Pluronic, have emerged as promising drug carriers, while cyclodextrins (CD), cyclic oligosaccharides with an apolar cavity, have long been used for their capacity to form inclusion complexes with drugs. Dimethylated β-cyclodextrin (DIMEB) has the capacity to fully breakup F127 Pluronic micelles, while this effect is substantially hindered if drugs are loaded within the micellar aggregates. Four drugs were studied at physiological temperature: lidocaine (LD), pentobarbital sodium salt (PB), sodium naproxen (NP), and sodium salicylate (SAL); higher temperatures shift the equilibrium toward higher drug partitioning and lower drug/CD binding compared to 25 °C ( Valero, M.; Dreiss, C. A. Growth, Shrinking, and Breaking of Pluronic Micelles in the Presence of Drugs and/or β-Cyclodextrin, a Study by Small-Angle Neutron Scattering and Fluorescence Spectroscopy . Langmuir 2010 , 26 , 10561 - 10571 ). The impact of drugs on micellar structure was characterized by small-angle neutron scattering (SANS), while their solubilization locus was revealed by 2D NOESY NMR. UV and fluorescence spectroscopy, Dynamic and Static Light Scattering were employed to measure a range of micellar properties and drug:CD interactions: binding constant, drug partitioning within the micelles, critical micellar concentration of the loaded micelles, aggregation number (N agg ). Critically, time-resolved SANS (TR-SANS) reveal that micellar breakup in the presence of drugs is substantially slower (100s of seconds) than for the free micelles (<100 ms) ( Valero, M.; Grillo, I.; Dreiss, C. A. Rupture of Pluronic Micelles by Di-Methylated β-Cyclodextrin Is Not Due to Polypseudorotaxane Formation . J. Phys. Chem. B 2012 , 116 , 1273 - 1281 ). These results combined together give new insights into the mechanisms of protection of the drugs against CD-induced micellar breakup. The outcomes are practical guidelines to improve the design of drug delivery systems

  19. Tamoxifen-loaded polymeric micelles: preparation, physico-chemical characterization and in vitro evaluation studies.

    Science.gov (United States)

    Cavallaro, Gennara; Maniscalco, Laura; Licciardi, Mariano; Giammona, Gaetano

    2004-11-20

    Several samples of polymeric micelles, formed by amphiphilic derivatives of PHEA, obtained by grafting into polymeric backbone of PEGs and/or hexadecylamine groups (PHEA-PEG-C(16) and PHEA-C(16)) and containing different amount of Tamoxifen, were prepared. All Tamoxifen-loaded polymeric micelles showed to increase drug water solubility. TEM studies provided evidence of the formation of supramolecular core/shell architectures containing drug, in the nanoscopic range and with spherical shape. Samples with different amount of encapsulated Tamoxifen were subjected to in vitro cytotoxic studies in order to evaluate the effect of Tamoxifen micellization on cell growth inhibition. All samples of Tamoxifen-loaded polymeric micelles showed a significantly higher antiproliferative activity in comparison with free drug, probably attributable to fluidification of cellular membranes, caused by amphiphilic copolymers, that allows a higher penetration of the drug into tumoral cells. To gain preliminary information about the potential use of prepared micelles as Tamoxifen drug delivery systems, studies evaluating drug release ability of micelle systems in media mimicking biological fluids (buffer solutions at pH 7.4 and 5.5) and in human plasma were carried out. These studies, performed evaluating the amount of Tamoxifen that remains in solution as a function of time, showed that at pH 7.4, as well as in plasma, PHEA-C(16) polymeric micelles were able to release lower drug amounts than PHEA-PEG(5000)-C(16) ones, while at pH 5.5, the behavior difference between two kind of micelles was less pronounced.

  20. Dependence of micelle size and shape on detergent alkyl chain length and head group.

    Science.gov (United States)

    Oliver, Ryan C; Lipfert, Jan; Fox, Daniel A; Lo, Ryan H; Doniach, Sebastian; Columbus, Linda

    2013-01-01

    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.

  1. 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.

  2. 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.

  3. Arborescent Unimolecular Micelles: Poly(γ-Benzyl l-Glutamate Core Grafted with a Hydrophilic Shell by Copper(I-Catalyzed Azide–Alkyne Cycloaddition Coupling

    Directory of Open Access Journals (Sweden)

    Mario Gauthier

    2017-10-01

    Full Text Available Amphiphilic copolymers were obtained by grafting azide-terminated polyglycidol, poly(ethylene oxide, or poly(2-hydroxyethyl acrylate chain segments onto alkyne-functionalized arborescent poly(γ-benzyl l-glutamate (PBG cores of generations G1–G3 via copper(I-catalyzed azide–alkyne Huisgen cycloaddition (CuAAC coupling. The alkyne functional groups on the arborescent PBG substrates were either distributed randomly or located exclusively at the end of the chains added in the last grafting cycle of the core synthesis. The location of these coupling sites influenced the ability of the arborescent copolymers to form unimolecular micelles in aqueous environments: The chain end grafting approach provided enhanced dispersibility in aqueous media and favored the formation of unimolecular micelles in comparison to random grafting. This is attributed to a better defined core-shell morphology for the copolymers with end-grafted shell segments. Aqueous solubility also depended on the type of material used for the shell chains. Coupling by CuAAC opens up possibilities for grafting a broad range of polymers on the arborescent substrates under mild conditions.

  4. Ring-Opening Polymerization of ε-Caprolactone Initiated by Ganciclovir (GCV for the Preparation of GCV-Tagged Polymeric Micelles

    Directory of Open Access Journals (Sweden)

    Alicia J. Sawdon

    2015-02-01

    Full Text Available Ganciclovir (GCV is a nucleoside analogue with antiviral activity against herpes viral infections, and the most widely used antiviral to treat cytomegalovirus infections. However, the low bioavailability and short half-life of GCV necessitate the development of a carrier for sustained delivery. In this study, guanosine-based GCV was used as the initiator directly in ring-opening polymerization of ε-caprolactone (ε-CL to form hydrophobic GCV-poly(caprolactone (GCV-PCL which was then grafted with hydrophilic chitosan to form amphiphilic copolymers for the preparation of stable micellar nanoparticles. Successful synthesis of GCV-PCL and GCV-PCL-chitosan were verified by 1H-NMR analysis. Self-assembled micellar nanoparticles were characterized by dynamic light scattering and zetasizer with an average size of 117 nm and a positive charge of 24.2 mV. The drug release kinetics of GCV was investigated and cytotoxicity assay demonstrated that GCV-tagged polymeric micelles were non-toxic. Our results showed that GCV could be used directly in the initiation of ring-opening polymerization of ε-CL and non-toxic polymeric micelles for GCV delivery can be formed.

  5. Direct Visualization of Conformation and Dense Packing of DNA-Based Soft Colloids

    Science.gov (United States)

    Zhang, Jing; Lettinga, Paul M.; Dhont, Jan K. G.; Stiakakis, Emmanuel

    2014-12-01

    Soft colloids—such as polymer-coated particles, star polymers, block-copolymer micelles, microgels—constitute a broad class of materials where microscopic properties such as deformability and penetrability of the particle play a key role in tailoring their macroscopic properties which is of interest in many technological areas. The ability to access these microscopic properties is not yet demonstrated despite its great importance. Here we introduce novel DNA-coated colloids with star-shaped architecture that allows accessing the above local structural information by directly visualizing their intramolecular monomer density profile and arm's free-end locations with confocal fluorescent microscopy. Compression experiments on a two-dimensional hexagonal lattice formed by these macromolecular assemblies reveal an exceptional resistance to mutual interpenetration of their charged corona at pressures approaching the MPa range. Furthermore, we find that this lattice, in a close packing configuration, is surprisingly tolerant to particle size variation. We anticipate that these stimuli-responsive materials could aid to get deeper insight in a wide range of problems in soft matter, including the study and design of biomimetic lubricated surfaces.

  6. Self-assembled micelles of amphiphilic poly(L-phenylalanine)-b-poly(L-serine) polypeptides for tumor-targeted delivery.

    Science.gov (United States)

    Zhao, Ziming; Wang, Yu; Han, Jin; Wang, Keli; Yang, Dan; Yang, Yihua; Du, Qian; Song, Yuanjian; Yin, Xiaoxing

    2014-01-01

    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 α-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 a positive role in the internalization of PFS. The more interesting thing was that the uptake inhibition impacted on normal cells but not on tumor cells at the physiological concentration of serine. The difference in the uptake of PFS micelles was fourfold as high between the tumor cells and the normal cells, which indicated that PFS micelles had good tumor targeting in vitro. In conclusion, PFS

  7. Cellular internalization of doxorubicin loaded star-shaped micelles with hydrophilic zwitterionic sulfobetaine segments.

    Science.gov (United States)

    Cao, Jun; Xie, Xiaoxiong; Lu, Aijing; He, Bin; Chen, Yuanwei; Gu, Zhongwei; Luo, Xianglin

    2014-05-01

    Four arm star-shaped poly(ε-caprolactone)-b-poly((N,N-diethylaminoethyl methacrylate)-r-(N-(3-sulfopropyl)-N-methacryloxyethy-N,N-diethylammoniumbetaine)) (4sPCLDEAS) micelles were loaded with anticancer drug doxorubicin to track their endocytosis in Hela cancer cell line. The effects of mean diameters and surface charges of the drug loaded micelles on the cellular uptake were studied in details. The results demonstrated that the internalization of micelles was both time and energy dependent process. Endocytic pathways including clathrin-mediated endocytosis, caveolae-mediated endocytosis and macropinocytosis were all involved in the internalization; caveolae-mediated endocytosis was the main pathway for the internalization of 4sPCLDEAS micelles. The assays for cell apoptosis and growth inhibition of tumor spheroids identified that these doxorubicin loaded micelles could induce cell apoptosis and inhibit tumor spheroids growth efficiently, which was even equal to free DOX·HCl. This study provided a rational design strategy for fabricating diverse micellar drug delivery systems with high anticancer efficiency. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Modulation of partition and localization of perfume molecules in sodium dodecyl sulfate micelles.

    Science.gov (United States)

    Fan, Yaxun; Tang, Haiqiu; Strand, Ross; Wang, Yilin

    2016-01-07

    The influence of perfume molecules on the self-assembly of the anionic surfactant sodium dodecyl sulfate (SDS) and their localization in SDS micelles have been investigated by ζ potential, small angle X-ray scattering (SAXS), one- and two-dimensional NMR and isothermal titration microcalorimetry (ITC). A broad range of perfume molecules varying in octanol/water partition coefficients P are employed. The results indicate that the surface charge, size and aggregation number of the SDS micelles strongly depend on the hydrophobicity/hydrophilicity degree of perfume molecules. Three distinct regions along the log P values are identified. Hydrophilic perfumes (log P perfumes (log P > 3.5) are solubilized close to the end of the hydrophobic chains in the SDS micelles and enlarge the micelles with higher ζ potential and a larger aggregation number. The incorporated fraction and micelle properties show increasing tendency for the perfumes in the intermediate log P region (2.0 perfume molecules also affects these properties. The perfumes with a linear chain structure or an aromatic group can penetrate into the palisade layer and closely pack with the SDS molecules. Furthermore, the thermodynamic parameters obtained from ITC show that the binding of the perfumes in the intermediate log P region is more spontaneous than those in the other two log P regions, and the micellization of SDS with the perfumes is driven by entropy.

  9. Hydrazone-Containing Triblock Copolymeric Micelles for pH-Controlled Drug Delivery

    Directory of Open Access Journals (Sweden)

    Peilan Qi

    2018-01-01

    Full Text Available In this study, the structure–activity relationship of amphiphilic block copolymer micelles as nanosized drug delivery system was revealed. Firstly, a biodegradable triblock polymers PEG-DiHyd-PLA containing hydrazone bond was synthesized through the ring-opening polymerization. In this method, PEG-DiHyd-Phenol was used as the initiator and L-lactide as the monomer. Then, the polymeric micelles were formed and used as nano-drug carriers with pH sensitivity. The structure and composition of the polymer were characterized by infrared (IR, nuclear magnetic resonance (1H-NMR, and gel permeation chromatography (GPC, we characterized the self-assembling process of the triblock polymers and the pH sensitivity of the micelles by the means of transmission electron microscopy (TEM, dynamic light scattering method (DLS. Doxorubicin (DOX acts as the model drug, and we researched the capacities of drug loading and release in vitro of the micelles. MTT experiments showed that the blank micelles of PEG-DiHyd-PLA were not cytotoxic to tumor cells (HepG-2, MCF-7 and normal cell (L-02 cells, but the DOX loaded ones displayed more toxicity than the ones without hydrazone, which was consistent to the further confocal laser scanning microscopy and flow cytometry study.

  10. Titration of fatty acids solubilized in cationic and anionic micelles. Calorimetry and thermodynamic modeling.

    Science.gov (United States)

    Söderman, Olle; Jönsson, Bengt; Olofsson, Gerd

    2006-02-23

    The electrostatic properties of charged surfactant micelles are investigated through titrations of fatty acid probes solubilized in the micelles. The titration process is followed by means of calorimetric measurements and by determining the pH values as a function of added base. This approach yields a complete thermodynamic description of the titration process. In particular, we find that the process is endothermic at 298 K. This is contrary to the titration of carboxylic acids in water, where DeltaH is approximately 0. To identify the main effect underlying the difference in DeltaH between titration in a micelle and water, a thermodynamic model has been developed which focuses on the transfer properties of charged and uncharged species from bulk water to the surface of a micelle and which incorporates a dielectric discontinuity at the micellar surface. The model relies on the use of the Poisson-Boltzmann equation which is solved using a finite element method. Experimental results and the model calculations imply that the dielectric discontinuity at (or near) the micellar surface plays a major role and hence must be included when analyzing the titration behavior of an acid functionality at the surface of a charged micelle.

  11. Fabrication of thermo-sensitive complex micelles for reversible cell targeting.

    Science.gov (United States)

    Wu, Yukun; Yang, Chengling; Lai, Quanyong; Zhang, Qian; Wang, Wei; Yuan, Zhi

    2015-11-01

    To ideally solve the contradiction between enhanced cellular uptake and prolonged blood circulation, reversible targeting polymeric micelles based on the expanding and shrinking behavior of a temperature-responsive polymer were developed. The micelle contained a hydrophobic PCL core and a mixed shell consisting of poly(N-isopropylacrylamide) (PNIPAAm) and biotin-terminated poly(ethylene glycol) (Biotin-PEG), and its targeting ability could be switched on/off by temperature. The cellular uptake of the complex polymeric micelles was studied. The results from a quantitative enzyme-linked immunosorbent assay (ELISA) indicated that the surface biotin content increased by as much as 11.6-fold when the temperature increased above the lower critical solution temperature (LCST). More importantly, the ELISA confirmed that biotin-mediated targeting on the surface was reversibly switched on and off for at least five cycles. In addition, the results from quantitative flow cytometry and confocal spectroscopy indicated that the cellular uptake of the targeted micelles at temperatures above the LCST was much higher than that at temperatures below the LCST. This complex polymeric micelle with reversible targeting property could be a promising alternative for drug delivery.

  12. Polymeric micelles for apoptosis-targeted optical imaging of cancer and intraoperative surgical guidance.

    Directory of Open Access Journals (Sweden)

    Hyunah Cho

    Full Text Available In a two-step strategy, an intraperitoneal (IP injection of poly(ethylene glycol-block-poly(ε-caprolactone (PEG-b-PCL micelles containing paclitaxel (PTX, cyclopamine (CYP, and gossypol (GSP at 30, 30, and 30 mg/kg, respectively, debulked tumor tissues by 1.3-fold, based on loss of bioluminescence with <10% body weight change, and induced apoptosis in peritoneal tumors when used as neoadjuvant chemotherapy (NACT in an ES-2-luc-bearing xenograft model for ovarian cancer. In a second step, a single intravenous (i.v. injection of apoptosis-targeting GFNFRLKAGAKIRFGS-PEG-b-PCL micelles containing a near-infrared (NIR fluorescence probe, DiR (1,1'-dioctadecyltetramethyl indotricarbocyanine iodide, resulted in increased peritoneal DiR accumulation in apoptosis-induced ES-2-luc tumor tissues (ex vivo by 1.5-fold compared with DiR molecules delivered by methoxy PEG-b-PCL micelles (non-targeted at 48 h after i.v. injection in a second step. As a result, a tandem of PEG-b-PCL micelles enabled high-resolution detection of ca. 1 mm diameter tumors, resulting in resection of approximately 90% of tumors, and a low peritoneal cancer index (PCI of ca. 7. Thus, a tandem of PEG-b-PCL micelles used for NCAT and NIR fluorescence imaging of therapy-induced apoptosis for intraoperative surgical guidance may be a promising treatment strategy for metastatic ovarian cancer.

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

    International Nuclear Information System (INIS)

    Tinoco, Luzineide W.; Gomes-Neto, Francisco; Valente, Ana Paula; Almeida, Fabio C. L.

    2007-01-01

    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 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

  14. 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.

  15. Polymeric topology and composition constrained polyether-polyester micelles for directional antitumor drug delivery.

    Science.gov (United States)

    Li, Di; Sun, Hai; Ding, Jianxun; Tang, Zhaohui; Zhang, Ying; Xu, Weiguo; Zhuang, Xiuli; Chen, Xuesi

    2013-11-01

    Amphiphilic linear and dumbbell-shaped poly(ethylene glycol)-poly(lactide-co-glycolide) (PEG-PLGA) copolymers were simply synthesized by the ring-opening polymerization of lactide and glycolide using PEG or tetrahydroxyl-functionalized PEG as the macroinitiator and stannous octoate as the catalyst. The copolymers spontaneously self-assembled into spherical micelles in phosphate-buffered saline at pH 7.4. The self-assembly behavior was dependent on both the polymeric topology and composition. Doxorubicin (DOX), an anthracycline antitumor drug, was loaded into micelles through nanoprecipitation. The in vitro release behavior could be adjusted by regulating the topology or composition of the copolymer, or the pH of the release medium. The effective intracellular DOX release from DOX-loaded micelles was confirmed by confocal laser scanning microscopy and flow cytometry in vitro. DOX-loaded micelles displayed great cellular proliferation inhibition efficacies after incubation for 24, 48 or 72 h. The hemolysis ratio of DOX was significantly reduced by the presence of copolymer. These properties indicated that the micelles derived from linear or dumbbell-shaped copolymers were promising candidates as smart antitumor drug carriers for malignancy therapy. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Olmesartan medoxomil-loaded mixed micelles: Preparation, characterization and in-vitro evaluation

    Directory of Open Access Journals (Sweden)

    Mohamed A. El-Gendy

    2017-12-01

    Full Text Available Olmesartan medoxomil (OLM is highly lipophilic in nature (log p = 4.31 which attributes to its low aqueous solubility contributing to its low bioavailability 25.6%. OLM was loaded into mixed micelles carriers in a trial to enhance its solubility, thus improving its oral bioavailability. OLM-loaded mixed micelles were prepared, using a Pluronic® mixture of F127 and P123, adopting the thin-film hydration method. Three drug: Pluronic® mixture ratios (1:40, 1:50and 1: 60 and various F127: P123 ratios were prepared. OLM Loaded mixed micelles showed stability up to 12 h. The particle size of the systems varied from 364.00 nm (F3 to 13.73 nm (F18 with accepted Poly dispersity index (PDI values. The in-vitro release studies of OLM from mixed micelles versus drug aqueous suspension were assessed using the reverse dialysis technique in a USP Dissolution tester apparatus (type II. The highest RE% (43% was achieved with OLM-loaded mixed micelles (F8 when compared to (35% of drug suspension.

  17. Membranes with charged nanopores from the assembly of random copolymer micelles

    Science.gov (United States)

    Asatekin, Ayse

    In this study, we aimed to prepare synthetic polymer membranes that can separate small molecule solutes based on charge by mimicking biological pores like ion channels: Pores 1-5 nm in diameter, lined with functional groups that interact with the target. We found that random copolymers that combine highly hydrophobic fluorinated repeat units of trifluoroethyl methacrylate with ionizable repeat units of methacrylic acid form micelles and vesicles in methanol. When these micelles are coated onto the surface of a porous support membrane whose pores are smaller than the micelles and then immersed into water, a selective layer of micelles packed together is formed. The gaps between the micelles act as carboxylate-functional nanochannels. The membrane showed charge-based selectivity between organic molecules, rejecting anionic solutes while passing neutral ones. The carboxyl groups can be post-functionalized to alter the selectivity of the membrane for desired separations. This shows the potential of using polymer self-assembly and functionality to design membranes that mimic biological pores while maintaining scalable manufacturing methods. We believe these approaches will eventually lead to novel membranes that can separate molecules of similar size but different chemical structure. We gratefully acknowledge financial support from Tufts University, the Tufts Collaborates program, and the National Science Foundation (NSF) under Grant No. CBET-1553661.

  18. IT-141, a Polymer Micelle Encapsulating SN-38, Induces Tumor Regression in Multiple Colorectal Cancer Models.

    Science.gov (United States)

    Carie, Adam; Rios-Doria, Jonathan; Costich, Tara; Burke, Brian; Slama, Richard; Skaff, Habib; Sill, Kevin

    2011-01-01

    Polymer micelles are promising drug delivery vehicles for the delivery of anticancer agents to tumors. Often, anticancer drugs display potent cytotoxic effects towards cancer cells but are too hydrophobic to be administered in the clinic as a free drug. To address this problem, a polymer micelle was designed using a triblock copolymer (ITP-101) that enables hydrophobic drugs to be encapsulated. An SN-38 encapsulated micelle, IT-141, was prepared that exhibited potent in vitro cytotoxicity against a wide array of cancer cell lines. In a mouse model, pharmacokinetic analysis revealed that IT-141 had a much longer circulation time, plasma exposure, and tumor exposure compared to irinotecan. IT-141 was also superior to irinotecan in terms of antitumor activity, exhibiting greater tumor inhibition in HT-29 and HCT116 colorectal cancer xenograft models at half the dose of irinotecan. The antitumor effect of IT-141 was dose-dependent and caused complete growth inhibition and tumor regression at well-tolerated doses. Varying the specific concentration of SN-38 within the IT-141 micelle had no detectible effect on this antitumor activity, indicating no differences in activity between different IT-141 formulations. In summary, IT-141 is a potent micelle-based chemotherapy that holds promise for the treatment of colorectal cancer.

  19. IT-141, a Polymer Micelle Encapsulating SN-38, Induces Tumor Regression in Multiple Colorectal Cancer Models

    Directory of Open Access Journals (Sweden)

    Adam Carie

    2011-01-01

    Full Text Available Polymer micelles are promising drug delivery vehicles for the delivery of anticancer agents to tumors. Often, anticancer drugs display potent cytotoxic effects towards cancer cells but are too hydrophobic to be administered in the clinic as a free drug. To address this problem, a polymer micelle was designed using a triblock copolymer (ITP-101 that enables hydrophobic drugs to be encapsulated. An SN-38 encapsulated micelle, IT-141, was prepared that exhibited potent in vitro cytotoxicity against a wide array of cancer cell lines. In a mouse model, pharmacokinetic analysis revealed that IT-141 had a much longer circulation time, plasma exposure, and tumor exposure compared to irinotecan. IT-141 was also superior to irinotecan in terms of antitumor activity, exhibiting greater tumor inhibition in HT-29 and HCT116 colorectal cancer xenograft models at half the dose of irinotecan. The antitumor effect of IT-141 was dose-dependent and caused complete growth inhibition and tumor regression at well-tolerated doses. Varying the specific concentration of SN-38 within the IT-141 micelle had no detectible effect on this antitumor activity, indicating no differences in activity between different IT-141 formulations. In summary, IT-141 is a potent micelle-based chemotherapy that holds promise for the treatment of colorectal cancer.

  20. Effects of sampling conditions on DNA-based estimates of American black bear abundance

    Science.gov (United States)

    Laufenberg, Jared S.; Van Manen, Frank T.; Clark, Joseph D.

    2013-01-01

    DNA-based capture-mark-recapture techniques are commonly used to estimate American black bear (Ursus americanus) population abundance (N). Although the technique is well established, many questions remain regarding study design. In particular, relationships among N, capture probability of heterogeneity mixtures A and B (pA and pB, respectively, or p, collectively), the proportion of each mixture (π), number of capture occasions (k), and probability of obtaining reliable estimates of N are not fully understood. We investigated these relationships using 1) an empirical dataset of DNA samples for which true N was unknown and 2) simulated datasets with known properties that represented a broader array of sampling conditions. For the empirical data analysis, we used the full closed population with heterogeneity data type in Program MARK to estimate N for a black bear population in Great Smoky Mountains National Park, Tennessee. We systematically reduced the number of those samples used in the analysis to evaluate the effect that changes in capture probabilities may have on parameter estimates. Model-averaged N for females and males were 161 (95% CI = 114–272) and 100 (95% CI = 74–167), respectively (pooled N = 261, 95% CI = 192–419), and the average weekly p was 0.09 for females and 0.12 for males. When we reduced the number of samples of the empirical data, support for heterogeneity models decreased. For the simulation analysis, we generated capture data with individual heterogeneity covering a range of sampling conditions commonly encountered in DNA-based capture-mark-recapture studies and examined the relationships between those conditions and accuracy (i.e., probability of obtaining an estimated N that is within 20% of true N), coverage (i.e., probability that 95% confidence interval includes true N), and precision (i.e., probability of obtaining a coefficient of variation ≤20%) of estimates using logistic regression. The capture probability

  1. Development of plumbagin-loaded phospholipid-Tween® 80 mixed micelles: formulation, optimization, effect on breast cancer cells and human blood/serum compatibility testing.

    Science.gov (United States)

    Bothiraja, Chellampillai; Kapare, Harshad S; Pawar, Atmaram P; Shaikh, Karimunnisa S

    2013-10-01

    Phospholipid and Tween(®) 80 mixed micelles were investigated as injectable nanocarriers for the natural anticancer compound, plumbagin (PBG), with the aim to improve anticancer efficiency. PBG-loaded mixed micelles were fabricated by self-assembly; composition being optimized using 3(2) factorial design. Optimized mixed micelles were spherical and 46 nm in size. Zeta potential, drug loading and encapsulation efficiency were 5.04 mV, 91.21 and 98.38% respectively. Micelles demonstrated sustained release of PBG. Micelles caused a 2.1-fold enhancement in vitro antitumor activity of PBG towards MCF-7 cells. Micelles proved safe for intravenous injection as PBG was stable at high pH; micelle size and encapsulation efficiency were retained upon dilution. Developed mixed micelles proved potential nanocarriers for PBG in cancer chemotherapy.

  2. 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...

  3. Environmental applications of lanthanide counterions bound to reverse micelles

    International Nuclear Information System (INIS)

    Warner, I.M.; Mwalupindi, A.G.; Ndou, T.T.

    1992-01-01

    The lanthanide surfactants of the formula [Ln(EHS) 3 ] [where EHS - bis(2-ethylhexyl) sulfosuccinate and Ln = Tb(III)or Eu(III)] have been synthesized from aerosol OT, and used to detect select organic analytes. This technique is based on the ability of the lanthanide ions to transform the energy absorbed by the organic compounds into a visible lanthanide ion emission via intermolecular energy transfer. When dissolved in an organic solvent, the surfactants form reverse micelles which provide molecular organization of the donor and acceptor species to come into close contact for energy transfer. An enhancement of the sensitized luminescence of the lanthanide counterions have been demonstrated in the presence of many organic analytes. The results show that a significant enhancement can be achieved by using an organic analyte containing a polar substituent. The observed efficient sensitization of the lanthanide ions is used for the determination of select organic analytes. Many of the organic analytes used are potential pollutants and carcinogens. Therefore, this procedure is more likely to provide a detection scheme to selectively analyze water for environmentally important pollutants such as polychlorobiphenyls. 1 H NMR spectroscopy has been used to establish the interaction between the organic analyte donor and lanthanide ion acceptor and then examine the relative locations of various photosensitive species present in the reverse micellar solution. This information was derived from changes in the chemical shift and resolution of both the analyte and the surfactant protons upon solubilization of the donor in the micellar solution. These data are used to estimate the average distance between the donor and the acceptor in this analytical scheme. The ability and the effectiveness of these surfactants to act as NME shift reagents is discussed

  4. Potential for DNA-based identification of Great Lakes fauna: Match and mismatch between taxa inventories and DNA barcode libraries

    Science.gov (United States)

    DNA-based identification of mixed-organism samples offers the potential to greatly reduce the need for resource-intensive morphological identification, which would be of value both to biotic condition assessment and non-native species early-detection monitoring. However, the abi...

  5. Oxidative DNA Base Damage in MCF-10A Breast Epithelial Cells at Clinically Achievable Concentrations of Doxorubicin

    Science.gov (United States)

    Gajewski, Ewa; Gaur, Shikha; Akman, Steven A.; Matsumoto, Linda; van Balgooy, Josephus N.A.; Doroshow, James H.

    2009-01-01

    The cellular metabolism of doxorubicin generates reactive oxygen species with significant potential to damage DNA. Such DNA damage can result in mutations if not adequately repaired by cellular DNA repair pathways. Secondary malignancies have been reported in patients who have received doxorubicin-containing chemotherapeutic regimens; however, the underlying molecular mechanism(s) to explain the development of these tumors remains under active investigation. We have previously demonstrated the presence of DNA bases modified by oxidation in the peripheral blood mononuclear cells of patients with breast cancer following treatment with doxorubicin. In those studies, doxorubicin was administered by continuous infusion over 96 hours to minimize the risk of cardiac toxicity. To evaluate potential mechanisms underlying doxorubicin-induced DNA base oxidation in non-malignant tissues, MCF-10A breast epithelial cells were cultured for 96 hours with the same doxorubicin concentration achieved in vivo (0.1 μM). During doxorubicin exposure, MCF-10A cells underwent growth arrest and apoptosis, developed elevated levels of reactive oxygen species, and demonstrated a time-dependent and significant increase in the levels of 11 oxidized DNA bases, as determined by gas chromatography/mass spectroscopy. Diminished expression of DNA repair enzymes was also observed over the same time course. Thus, clinically achievable concentrations of doxorubicin induce a level of oxidative stress in MCF-10A cells that is capable of oxidizing DNA bases and significantly altering cellular proliferation. PMID:17445777

  6. A Ligand Structure-Activity Study of DNA-Based Catalytic Asymmetric Hydration and Diels-Alder Reactions

    NARCIS (Netherlands)

    Rosati, F.; Roelfes, J.G.

    A structure-activity relationship study of the first generation ligands for the DNA-based asymmetric hydration of enones and Diels-Alder reaction in water is reported. The design of the ligand was optimized resulting in a maximum ee of 83% in the hydration reaction and 75% in the Diels-Alder

  7. Traditional Mold Analysis Compared to a DNA-based Method of Mold Analysis with Applications in Asthmatics' Homes

    Science.gov (United States)

    Traditional environmental mold analysis is based-on microscopic observations and counting of mold structures collected from the air on a sticky surface or culturing of molds on growth media for identification and quantification. A DNA-based method of mold analysis called mol...

  8. 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.

  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. Structure of the C-terminal Region of the Frizzled Receptor 1 in Detergent Micelles

    Directory of Open Access Journals (Sweden)

    CongBao Kang

    2013-07-01

    Full Text Available The C-terminal domains of the Frizzleds (FZDs contain a short conserved motif (KTXXXW. It has been demonstrated that FZDs interacted with the PDZ domain of the cytoplasmic proteins such as Dishevelled through this motif and mutations in this motif disrupted Wnt/β-catenin signaling. We carried out structural studies for a peptide derived from the C-terminal domain of the FZD1 in different solvents using circular dichroism and solution NMR spectroscopy. Our results showed that this domain was unstructured in an aqueous solution and formed a helical structure in detergent micelles. Fluorescence studies suggested that the tryptophan residue (W630 in the motif interacted with micelles. The solution structure of the peptide in sodium dodecyl sulfate micelles was determined and an amphipathic helix was identified. This helix may have similar function to the helix 8 of other G protein-coupled receptors.

  11. Pseudo-biphasic extraction and liquid membrane transport of ionic solutes using micelle-based processes

    International Nuclear Information System (INIS)

    Tondre, Ch.

    1995-01-01

    Different aspects between micellar extraction and solvent extraction were discussed. One way of using micellar systems to perform metal ion extraction consists in solubilizing lipophilic complexing agents in the hydrophobic core of the micelles, similarly to their solubilization in the organic phase in classical biphasic extraction. Metal ions dissolved in the continuous phase will be complexed or not, depending on their affinity for the micelle-solubilized extractant, the microscopic micelle/water interface playing a part analogous to the macroscopic organic/water interface in biphasic extraction. The yields of extraction (after ultrafiltration of the micellar pseudo-phase) when parameters such as the extractant/metal ratio or the extractant hydrophobicity are changed, show similar trends as those reported in the case of solvent extraction, but only diluted solutions can be treated that way. 14 refs

  12. Study of the interaction of potassium ion channel protein with micelle by molecular dynamics simulation

    Science.gov (United States)

    Shantappa, Anil; Talukdar, Keka

    2018-04-01

    Ion channels are proteins forming pore inside the body of all living organisms. This potassium ion channel known as KcsA channel and it is found in the each cell and nervous system. Flow of various ions is regulated by the function of the ion channels. The nerve ion channel protein with protein data bank entry 1BL8, which is basically an ion channel protein in Streptomyces Lividans and which is taken up to form micelle-protein system and the system is analyzed by using molecular dynamics simulation. Firstly, ion channel pore is engineered by CHARMM potential and then Micelle-protein system is subjected to molecular dynamics simulation. For some specific micelle concentration, the protein unfolding is observed.

  13. Polymeric micelles as a drug delivery system enhance cytotoxicity of vinorelbine through more intercellular accumulation.

    Science.gov (United States)

    Lu, Xiaoyan; Zhang, Fayun; Qin, Lei; Xiao, Fengying; Liang, Wei

    2010-05-01

    Polymeric micelles had been used as an efficacious carrier system for anti-cancer drug delivery. However, it is not clear whether the molecular mechanism of drug encapsulated in micelles is same as free drug. In this study, the mechanism of vinorelbine loaded in glycol-phosphatidylethanolamine (PEG-PE) micelles (M-Vino) on tumor cells was investigated. Compared with free vinorelbine (Free Vino), M-Vino was more effective in inhibiting the growth of tumor cells in vitro, inducing G(2)/M phase arrest and apoptosis of tumor cells. M-Vino showed a faster entry and higher accumulation in 4T1 cells than free vinorelbine. Therefore, M-Vino destabilized microtubules, induced cell death, and enhanced its cytotoxicity through more intercellular accumulation of vinorelbine.

  14. Phase behavior of casein micelles/exocellular polysaccharide mixtures: Experiment and theory

    Science.gov (United States)

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

    1999-05-01

    Dispersions of casein micelles and an exocellular polysaccharide (EPS), obtained from Lactococcus lactis subsp. cremoris NIZO B40 EPS, show a phase separation. The phase separation is of the colloidal gas-liquid type. We have determined a phase diagram that describes the separation of skim milk with EPS into a casein-micelle rich phase and an EPS rich phase. We compare the phase diagram with those calculated from theories developed by Vrij, and by Lekkerkerker and co-workers, showing that the experimental phase boundary can be predicted quite well. From dynamic light scattering measurements of the self-diffusion of the casein micelles in the presence of EPS the spinodal could be located and it corresponds with the experimental phase boundary.

  15. Biocompatible Polyhydroxyethylaspartamide-based Micelles with Gadolinium for MRI Contrast Agents

    Directory of Open Access Journals (Sweden)

    Kim Hyo Jeong

    2010-01-01

    Full Text Available Abstract Biocompatible poly-[N-(2-hydroxyethyl-d,l-aspartamide]-methoxypoly(ethyleneglycol-hexadecylamine (PHEA-mPEG-C16 conjugated with 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid-gadolinium (DOTA-Gd via ethylenediamine (ED was synthesized as a magnetic resonance imaging (MRI contrast agent. Amphiphilic PHEA-mPEG-C16-ED-DOTA-Gd forms micelle in aqueous solution. All the synthesized materials were characterized by proton nuclear magnetic resonance (1H NMR. Micelle size and shape were examined by dynamic light scattering (DLS and atomic force microscopy (AFM. Micelles with PHEA-mPEG-C16-ED-DOTA-Gd showed higher relaxivities than the commercially available gadolinium contrast agent. Moreover, the signal intensity of a rabbit liver was effectively increased after intravenous injection of PHEA-mPEG-C16-ED-DOTA-Gd.

  16. The α-chymotrypsin and its hydrophobic derivatives in inverse micelles

    International Nuclear Information System (INIS)

    Pitre, Franck

    1993-01-01

    The α-chymotrypsin is among the most used enzymes, notably and particularly in medicine for therapeutic treatments as well as in biochemistry to determine the amine acid sequence of proteins. This research thesis addresses the study of interactions between a micro-emulsion system and an enzymatic system, and more particularly the behaviour of α-chymotrypsin in AOT inverse micelles. After a brief description of the inverse micellar system and of previously obtained results on the solubilisation of α-chymotrypsin in inverse micelles, the author reports the study of the inverse micellar phase in presence of α-chymotrypsin at the vicinity of the maximum solubility. Various techniques are used for this purpose: UV-visible absorption spectrophotometry, conductometry, and X ray scattering. Then, the author describes the chemical modification of α-chymotrypsin, and reports the study of structural as well as reaction modifications introduced during the solubilisation of α-chymotrypsin modified in inverse micelles [fr

  17. Morphology, stability, and X-ray absorption spectroscopic study of iron oxide (Hematite) nanoparticles prepared by micelle nanolithography

    Science.gov (United States)

    Bera, Anupam; Bhattacharya, Atanu; Tiwari, N.; Jha, S. N.; Bhattacharyya, D.

    2018-03-01

    Currently, considerable effort is being made towards synthesis and characterization of iron oxide nanoparticles. In this article, we report on the preparation and characterization of iron oxide nanoparticle (NP) arrays supported on natively oxidized Si(100) surface. The NPs are synthesized by reverse micelle nanolithography technique and are then deposited onto natively oxidized Si(100) surface via spin-coating. Plasma oxidation followed by high temperature annealing results in a unimodal size distribution of pseudohexagonally-ordered array of iron oxide NPs (with ∼14 nm mean diameter and ∼5 nm mean height). High temperature annealing does not fragment the NPs. Particles are sinter-resistant: the unimodal arrays are robust with respect to thermal treatment. X-ray absorption spectroscopy (XAS), including X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS), reveals that structure of the iron oxide particle resembles closely the hematite α-Fe2O3 structure. Furthermore, with the help of EXAFS spectra, we eliminate the possibility of γ-Fe2O3, Fe3O4, FeO and FeO(OH) structures for the NPs.

  18. Use of H19 Gene Regulatory Sequences in DNA-Based Therapy for Pancreatic Cancer

    Directory of Open Access Journals (Sweden)

    V. Scaiewicz

    2010-01-01

    Full Text Available Pancreatic cancer is the eighth most common cause of death from cancer in the world, for which palliative treatments are not effective and frequently accompanied by severe side effects. We propose a DNA-based therapy for pancreatic cancer using a nonviral vector, expressing the diphtheria toxin A chain under the control of the H19 gene regulatory sequences. The H19 gene is an oncofetal RNA expressed during embryo development and in several types of cancer. We tested the expression of H19 gene in patients, and found that 65% of human pancreatic tumors analyzed showed moderated to strong expression of the gene. In vitro experiments showed that the vector was effective in reducing Luciferase protein activity on pancreatic carcinoma cell lines. In vivo experiment results revealed tumor growth arrest in different animal models for pancreatic cancer. Differences in tumor size between control and treated groups reached a 75% in the heterotopic model (P=.037 and 50% in the orthotopic model (P=.007. In addition, no visible metastases were found in the treated group of the orthotopic model. These results indicate that the treatment with the vector DTA-H19 might be a viable new therapeutic option for patients with unresectable pancreatic cancer.

  19. Dihydropyridines decrease X-ray-induced DNA base damage in mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Wojewodzka, M., E-mail: marylaw@ichtj.waw.pl [Center of Radiobiology and Biological Dosimetry, Institute of Nuclear Chemistry and Technology, Warszawa (Poland); Gradzka, I.; Buraczewska, I.; Brzoska, K.; Sochanowicz, B. [Center of Radiobiology and Biological Dosimetry, Institute of Nuclear Chemistry and Technology, Warszawa (Poland); Goncharova, R.; Kuzhir, T. [Institute of Genetics and Cytology, Belarussian National Academy of Sciences, Minsk (Belarus); Szumiel, I. [Center of Radiobiology and Biological Dosimetry, Institute of Nuclear Chemistry and Technology, Warszawa (Poland)

    2009-12-01

    Compounds with the structural motif of 1,4-dihydropyridine display a broad spectrum of biological activities, often defined as bioprotective. Among them are L-type calcium channel blockers, however, also derivatives which do not block calcium channels exert various effects at the cellular and organismal levels. We examined the effect of sodium 3,5-bis-ethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine-4-carboxylate (denoted here as DHP and previously also as AV-153) on X-ray-induced DNA damage and mutation frequency at the HGPRT (hypoxanthine-guanine phosphoribosyl transferase) locus in Chinese hamster ovary CHO-K1 cells. Using formamido-pyrimidine glycosylase (FPG) comet assay, we found that 1-h DHP (10 nM) treatment before X-irradiation considerably reduced the initial level of FPG-recognized DNA base damage, which was consistent with decreased 8-oxo-7,8-dihydro-2'-deoxyguanosine content and mutation frequency lowered by about 40%. No effect on single strand break rejoining or on cell survival was observed. Similar base damage-protective effect was observed for two calcium channel blockers: nifedipine (structurally similar to DHP) or verapamil (structurally unrelated). So far, the specificity of the DHP-caused reduction in DNA damage - practically limited to base damage - has no satisfactory explanation.

  20. Mitochondrial DNA-based identification of some forensically important blowflies in Thailand.

    Science.gov (United States)

    Preativatanyou, Kanok; Sirisup, Nantana; Payungporn, Sunchai; Poovorawan, Yong; Thavara, Usavadee; Tawatsin, Apiwat; Sungpradit, Sivapong; Siriyasatien, Padet

    2010-10-10

    Accurate identification of insects collected from death scenes provides not only specific developmental data assisting forensic entomologists to determine the postmortem interval more precisely but also other kinds of forensic evidence. However, morphological identification can be complicated due to the similarity among species, especially in the early larval stages. To simplify and make the species identification more practical and reliable, DNA-based identification is preferentially considered. In this study, we demonstrate the application of partial mitochondrial cytochrome oxidase I (COI) and cytochrome oxidase II (COII) sequences for differentiation of forensically important blowflies in Thailand; Chrysomya megacephala, Chrysomya rufifacies and Lucilia cuprina by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The PCR yields a single 1324bp-sized amplicon in all blowfly specimens, followed by direct DNA sequencing. Taq(α)I and VspI predicted from the sequencing data provide different RFLP profiles among these three species. Sequence analysis reveals no significant intraspecific divergence in blowfly specimens captured from different geographical regions in Thailand. Accordingly, neighbor-joining tree using Kimura's 2-parameter model illustrates reciprocal monophyly between species. Thus, these approaches serve as promising tools for molecular identification of these three common forensically important blowfly species in Thailand. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  1. From Pharmacognosia to DNA-Based Medicinal Plant Authentication - Pharmacognosy through the Centuries.

    Science.gov (United States)

    Heinrich, Michael; Anagnostou, Sabine

    2017-10-01

    For centuries, pharmacognosy was essential for the identification, quality, purity, and, until the end of the 18th century, even for the efficacy of medicinal plants. Since the 19th century, it concentrated on authenticity, purity, quality and the analysis of active substances, and was established as an academic branch discipline within pharmacy and continuously developed into a modern, highly sophisticated science. Even though the paradigm in pharmacy changed in the 19th century with the discovery of morphine and concentrated on single substances that could be synthesized fast by the upcoming industry, medicinal plants always remained an important element of the Materia medica, and during the last decades, medicinal plants continue to be a source of remedies, and natural products are an inspiration for new medicine. In this research, pharmacognostic skills remain an essential element, both with regards to identity, quality assurance of botanicals (both herbal medicines and supplements), and the discovery and development of new medicines. Over the years, the specific pharmacognostical tools have changed dramatically, and most recently, DNA-based techniques have become another element of our spectrum of scientific methods. Georg Thieme Verlag KG Stuttgart · New York.

  2. A new multilocus approach for a reliable DNA-based identification of Armillaria species.

    Science.gov (United States)

    Tsykun, Tetyana; Rigling, Daniel; Prospero, Simone

    2013-01-01

    In this paper we highlight and critically discuss limitations to molecular methods for identification of fungi via the example of the basidiomycete genus Armillaria. We analyzed a total of 144 sequences of three DNA regions commonly used for identifying fungi (ribosomal IGS-1 and ITS regions, translation elongation factor-1 alpha gene) from 48 specimens of six Armillaria species occurring in Europe (A. cepistipes, A. ostoyae, A. gallica, A. borealis, A. mellea, A. tabescens). Species were identified by comparing newly obtained sequences with those from the NCBI database, phylogenetic analyses and PCR-RFLP analyses of the three regions considered. When analyzed separately, no single gene region could unambiguously identify all six Armillaria species because of low interspecific and high intrasequence variability. We therefore developed a multilocus approach, which involves the stepwise use of the three regions. Following this scheme, all six species could be clearly discriminated. Our study suggests that, to improve the reliability of DNA-based techniques for species identification, multiple genes or intergenic regions should be analyzed.

  3. Horses for courses: a DNA-based test for race distance aptitude in thoroughbred racehorses.

    Science.gov (United States)

    Hill, Emmeline W; Ryan, Donal P; MacHugh, David E

    2012-12-01

    Variation at the myostatin (MSTN) gene locus has been shown to influence racing phenotypes in Thoroughbred horses, and in particular, early skeletal muscle development and the aptitude for racing at short distances. Specifically, a single nucleotide polymorphism (SNP) in the first intron of MSTN (g.66493737C/T) is highly predictive of best race distance among Flat racing Thoroughbreds: homozygous C/C horses are best suited to short distance races, heterozygous C/T horses are best suited to middle distance races, and homozygous T/T horses are best suited to longer distance races. Patent applications for this gene marker association, and other linked markers, have been filed. The information contained within the patent applications is exclusively licensed to the commercial biotechnology company Equinome Ltd, which provides a DNA-based test to the international Thoroughbred horse racing and breeding industry. The application of this information in the industry enables informed decision making in breeding and racing and can be used to assist selection to accelerate the rate of change of genetic types among distinct populations (Case Study 1) and within individual breeding operations (Case Study 2).

  4. Self-assembling of calcium salt of the new DNA base 5-carboxylcytosine

    Energy Technology Data Exchange (ETDEWEB)

    Irrera, Simona [Department of Chemistry, SAPIENZA University of Rome, Piazzale A. Moro 5, 00185 Rome (Italy); Department of Chemistry, University College London, 20 Grodon Street, WC1H0AJ London (United Kingdom); Ruiz-Hernandez, Sergio E. [School of Chemistry, Cardiff University Main Building, Park Place, CF103AT Cardiff (United Kingdom); Reggente, Melania [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Passeri, Daniele, E-mail: daniele.passeri@uniroma1.it [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Natali, Marco [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Gala, Fabrizio [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Department of Medical-Surgical, Techno-Biomedical Sciences and Translational Medicine of SAPIENZA University of Rome, Sant’Andrea Hospital, Rome (Italy); Zollo, Giuseppe [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Rossi, Marco [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Research Center for Nanotechnology applied to Engineering of SAPIENZA University of Rome (CNIS), Piazzale A. Moro 5, 00185 Rome (Italy); Portalone, Gustavo, E-mail: gustavo.portalone@uniroma1.it [Department of Chemistry, SAPIENZA University of Rome, Piazzale A. Moro 5, 00185 Rome (Italy)

    2017-06-15

    Highlights: • Ca salt of 5-carboxylcytosine has been deposited on HOPG substrate. • Molecules self-assembled in monolayers and filaments. • Height of the features were measured by atomic force microscopy. • Ab-initio calculations confirmed the AFM results. - Abstract: Supramolecular architectures involving DNA bases can have a strong impact in several fields such as nanomedicine and nanodevice manufacturing. To date, in addition to the four canonical nucleobases (adenine, thymine, guanine and cytosine), four other forms of cytosine modified at the 5 position have been identified in DNA. Among these four new cytosine derivatives, 5-carboxylcytosine has been recently discovered in mammalian stem cell DNA, and proposed as the final product of the oxidative epigenetic demethylation pathway on the 5 position of cytosine. In this work, a calcium salt of 5-carboxylcytosine has been synthesized and deposited on graphite surface, where it forms self-assembled features as long range monolayers and up to one micron long filaments. These structures have been analyzed in details combining different theoretical and experimental approaches: X-ray single-crystal diffraction data were used to simulate the molecule-graphite interaction, first using molecular dynamics and then refining the results using density functional theory (DFT); finally, data obtained with DFT were used to rationalize atomic force microscopy (AFM) results.

  5. Self-assembling of calcium salt of the new DNA base 5-carboxylcytosine

    Science.gov (United States)

    Irrera, Simona; Ruiz-Hernandez, Sergio E.; Reggente, Melania; Passeri, Daniele; Natali, Marco; Gala, Fabrizio; Zollo, Giuseppe; Rossi, Marco; Portalone, Gustavo

    2017-06-01

    Supramolecular architectures involving DNA bases can have a strong impact in several fields such as nanomedicine and nanodevice manufacturing. To date, in addition to the four canonical nucleobases (adenine, thymine, guanine and cytosine), four other forms of cytosine modified at the 5 position have been identified in DNA. Among these four new cytosine derivatives, 5-carboxylcytosine has been recently discovered in mammalian stem cell DNA, and proposed as the final product of the oxidative epigenetic demethylation pathway on the 5 position of cytosine. In this work, a calcium salt of 5-carboxylcytosine has been synthesized and deposited on graphite surface, where it forms self-assembled features as long range monolayers and up to one micron long filaments. These structures have been analyzed in details combining different theoretical and experimental approaches: X-ray single-crystal diffraction data were used to simulate the molecule-graphite interaction, first using molecular dynamics and then refining the results using density functional theory (DFT); finally, data obtained with DFT were used to rationalize atomic force microscopy (AFM) results.

  6. DNA-based construction at the nanoscale: emerging trends and applications

    Science.gov (United States)

    Lourdu Xavier, P.; Chandrasekaran, Arun Richard

    2018-02-01

    The field of structural DNA nanotechnology has evolved remarkably—from the creation of artificial immobile junctions to the recent DNA-protein hybrid nanoscale shapes—in a span of about 35 years. It is now possible to create complex DNA-based nanoscale shapes and large hierarchical assemblies with greater stability and predictability, thanks to the development of computational tools and advances in experimental techniques. Although it started with the original goal of DNA-assisted structure determination of difficult-to-crystallize molecules, DNA nanotechnology has found its applications in a myriad of fields. In this review, we cover some of the basic and emerging assembly principles: hybridization, base stacking/shape complementarity, and protein-mediated formation of nanoscale structures. We also review various applications of DNA nanostructures, with special emphasis on some of the biophysical applications that have been reported in recent years. In the outlook, we discuss further improvements in the assembly of such structures, and explore possible future applications involving super-resolved fluorescence, single-particle cryo-electron (cryo-EM) and x-ray free electron laser (XFEL) nanoscopic imaging techniques, and in creating new synergistic designer materials.

  7. Advanced DNA-Based Point-of-Care Diagnostic Methods for Plant Diseases Detection

    Directory of Open Access Journals (Sweden)

    Han Yih Lau

    2017-12-01

    Full Text Available Diagnostic technologies for the detection of plant pathogens with point-of-care capability and high multiplexing ability are an essential tool in the fight to reduce the large agricultural production losses caused by plant diseases. The main desirable characteristics for such diagnostic assays are high specificity, sensitivity, reproducibility, quickness, cost efficiency and high-throughput multiplex detection capability. This article describes and discusses various DNA-based point-of care diagnostic methods for applications in plant disease detection. Polymerase chain reaction (PCR is the most common DNA amplification technology used for detecting various plant and animal pathogens. However, subsequent to PCR based assays, several types of nucleic acid amplification technologies have been developed to achieve higher sensitivity, rapid detection as well as suitable for field applications such as loop-mediated isothermal amplification, helicase-dependent amplification, rolling circle amplification, recombinase polymerase amplification, and molecular inversion probe. The principle behind these technologies has been thoroughly discussed in several review papers; herein we emphasize the application of these technologies to detect plant pathogens by outlining the advantages and disadvantages of each technology in detail.

  8. Release, Partitioning, and Conjugation Stability of Doxorubicin in Polymer Micelles Determined by Mechanistic Modeling

    Science.gov (United States)

    Ponta, Andrei; Fugit, Kyle D.; Anderson, Bradley D.; Bae, Younsoo

    2014-01-01

    Purpose To better understand the mechanistic parameters that govern drug release from polymer micelles with acid-labile linkers. Methods A mathematical model was developed to describe drug release from block copolymer micelles composed of a poly(ethylene glycol) shell and a poly(aspartate) core, modified with drug binding linkers for pH-controlled release [hydrazide (HYD), aminobenzoate-hydrazide (ABZ), or glycine-hydrazide (GLY)]. Doxorubicin (Dox) was conjugated to the block copolymers through acid-labile hydrazone bonds. The polymer drug conjugates were used to prepare three polymer micelles (HYD-M, ABZ-M, and GLY-M). Drug release studies were performed to identify the factors governing pH-sensitive release of Dox. The effect of prolonged storage of copolymer material on release kinetics was also observed. Results Biphasic drug release kinetics were observed for all three micelle formulations. The developed model was able to quantify observed release kinetics upon the inclusion of terms for unconjugated Dox and two populations of conjugated Dox. Micelle/water partitioning of Dox was also incorporated into the model and found significant in all micelles under neutral conditions but reduced under acidic conditions. The drug binding linker played a major role in drug release as the extent of Dox release at specific time intervals was greater at pH 5.0 than at pH 7.4 (HYD-M > ABZ-M > GLY-M). Mathematical modeling was also able correlate changes in release kinetics with the instability of the hydrazone conjugation of DOX during prolonged storage. Conclusion These results illustrate the potential utility of mechanistic modeling to better assess release characteristics intrinsic to a particular drug/nanoparticle system. PMID:25407546

  9. mPEG-PLA Micelle for Delivery of Effective Parts of Andrographis Paniculata.

    Science.gov (United States)

    Yao, Hailu; Song, Shiyong; Miao, Xiaolu; Liu, Xiao; Wang, Zhen; Shao, Xiaoting; Zhang, Yu; Han, Guang

    2017-11-19

    Many studies have shown that Andrographis paniculata (Burm. f.) Nees has a good anti-tumor effect, but poor solubility in water and poor bioavailability hinder the modernization of it. To formulate the effective parts (mainly diterpene lactones) of Andrographis paniculata (AEP) into targeting drug delivery system, a series of poly(ethylene glycol)-poly(D.L-lactic acid)(mPEG-PLA) with different ratio of hydrophilic and hydrophobic segment were synthetized to encapsulate AEP. AEP micelles were prepared by a simple solvent-evaporation method. According to the loading capacity, the best polymer was chosen. mPEG-PLA micelles were characterized in terms of drug entrapping efficiency, loading capacity, size, the crystalline state of AEP, stability and release profile. Meanwhile the cytotoxicity of micelles on mouse breast cancer 4T-1 was investigated. These micelle (mPEG-PLA-AEP) particles had a size of (92.84±5.63) nm and a high entrapping efficiency and loading capacity of (91.00±11.53)% and (32.14±3.02)%(w/w), respectively. The powder DSC showed that drugs were well encapsulated in the core of micelles. mPEG-PLA-AEP had a good stability against salt dissociation, protein adsorption and anion substitution and the solubility of andrographolide (AG) and 14-deoxy-11,12-didehydroandrographolide(DDAG) in AEP increased 4.51 times and 2.12 times in water, and the solubility of DAG has no difference. mPEG-PLA-AEP had the same release profile in different dissolution medium. Cytotoxicity testing in vitro demonstrated that mPEG-PLA-AEP exhibited higher cell viability inhibition in mouse breast cancer 4T-1 than free AEP. mPEG-PLA micelles offer a promising alternative for TCM therapy with higher solubility and improved antitumor effect. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  10. Biodegradable micelles enhance the antiglioma activity of curcumin in vitro and in vivo

    Directory of Open Access Journals (Sweden)

    Zheng S

    2016-06-01

    Full Text Available Songping Zheng,1,* Xiang Gao,1,2,* Xiaoxiao Liu,1 Ting Yu,1 Tianying Zheng,1 Yi Wang,1 Chao You1 1Department of Neurosurgery, West China Hospital, West China Medical School, Sichuan University, Chengdu, People’s Republic of China; 2Department of Pharmacology, Yale School of Medicine, Yale University, New Haven, CT, USA *These authors contributed equally to this work Abstract: Curcumin (Cur, a natural polyphenol of Curcuma longa, has been recently reported to possess antitumor activities. However, due to its poor aqueous solubility and low biological availability, the clinical application of Cur is quite limited. The encapsulation of hydrophobic drugs into nanoparticles is an effective way to improve their pharmaceutical activities. In this research, nanomicelles loaded with Cur were formulated by a self-assembly method with biodegradable monomethoxy poly(ethylene glycol-poly(lactide copolymers (MPEG-PLAs. After encapsulation, the cellular uptake was increased and Cur could be released from MPEG-PLA micelles in a sustained manner. The Cur-loaded MPEG-PLA micelles (Cur/MPEG-PLA micelles exhibited an enhanced toxicity on C6 and U251 glioma cells and induced more apoptosis on C6 glioma cells compared with free Cur. Moreover, the therapy efficiency of Cur/MPEG-PLA micelles was evaluated at length on a nude mouse model bearing glioma. The Cur/MPEG-PLA micelles were more effective on suppressing tumor growth compared with free Cur, which indicated that Cur/MPEG-PLA micelles improved the antiglioma activity of Cur in vivo. The results of immunohistochemical and immunofluorescent analysis indicated that the induction of apoptosis, antiangiogenesis, and inhibition of cell proliferation may contribute to the improvement in antiglioma effects. Our data suggested that Cur/MPEG-PLA may have potential clinic applications in glioma therapy. Keywords: curcumin, glioma, cell apoptosis, cell proliferation, angiogenesis 

  11. Multicompartment micelles with adjustable poly(ethylene glycol) shell for efficient in vivo photodynamic therapy.

    Science.gov (United States)

    Synatschke, Christopher V; Nomoto, Takahiro; Cabral, Horacio; Förtsch, Melanie; Toh, Kazuko; Matsumoto, Yu; Miyazaki, Kozo; Hanisch, Andreas; Schacher, Felix H; Kishimura, Akihiro; Nishiyama, Nobuhiro; Müller, Axel H E; Kataoka, Kazunori

    2014-02-25

    We describe the preparation of well-defined multicompartment micelles from polybutadiene-block-poly(1-methyl-2-vinyl pyridinium methyl sulfate)-block-poly(methacrylic acid) (BVqMAA) triblock terpolymers and their use as advanced drug delivery systems for photodynamic therapy (PDT). A porphyrazine derivative was incorporated into the hydrophobic core during self-assembly and served as a model drug and fluorescent probe at the same time. The initial micellar corona is formed by negatively charged PMAA and could be gradually changed to poly(ethylene glycol) (PEG) in a controlled fashion through interpolyelectrolyte complex formation of PMAA with positively charged poly(ethylene glycol)-block-poly(L-lysine) (PLL-b-PEG) diblock copolymers. At high degrees of PEGylation, a compartmentalized micellar corona was observed, with a stable bottlebrush-on-sphere morphology as demonstrated by cryo-TEM measurements. By in vitro cellular experiments, we confirmed that the porphyrazine-loaded micelles were PDT-active against A549 cells. The corona composition strongly influenced their in vitro PDT activity, which decreased with increasing PEGylation, correlating with the cellular uptake of the micelles. Also, a PEGylation-dependent influence on the in vivo blood circulation and tumor accumulation was found. Fully PEGylated micelles were detected for up to 24 h in the bloodstream and accumulated in solid subcutaneous A549 tumors, while non- or only partially PEGylated micelles were rapidly cleared and did not accumulate in tumor tissue. Efficient tumor growth suppression was shown for fully PEGylated micelles up to 20 days, demonstrating PDT efficacy in vivo.

  12. Molecular dynamics studies of PEGylated α-helical coiled coils and their self-assembled micelles.

    Science.gov (United States)

    Woo, Sun Young; Lee, Hwankyu

    2014-07-29

    We performed coarse-grained (CG) molecular dynamics simulations of trimeric α-helical coiled coils grafted with poly(ethylene glycol) (PEG) of different sizes and conjugate positions and the self-assembled micelle of amphiphilic trimers. The CG model for the trimeric coiled coil is verified by comparing the α-helical structure and interhelical distance with those calculated from all-atom simulations. In CG simulations of PEGylated trimers, the end-to-end distances and radii of gyration of PEGs grafted to the sides of peptides become shorter than those of free PEGs in water, which agrees with experiments. This shorter size of the grafted PEGs is also confirmed by calculating the thickness of the PEG layer, which is less than the size of the mushroom. These indicate the adsorption of PEG chains onto coiled coils since hydrophobic residues in the exterior sites of coiled coils tend to be less exposed to water and thus interact with PEGs, leading to the compact conformation of adsorbed PEGs. Simulations of the self-assembly of amphiphilic trimers show that the randomly distributed trimers self-assemble to micelles. The outer radius and hydrodynamic radius of the micelle, which were calculated respectively from radial densities and diffusion coefficients, are ∼7 nm, in agreement with the experimental value of ∼7.5 nm, while the aggregation number of amphiphilic molecules per micelle is lower than the experimentally proposed value. These simulations predict the experimentally measured size of PEGs grafted to the trimeric coiled coils and their self-assembled amphiphilic micelles and suggest that the aggregation number of the micelle may be lower, which needs to be confirmed by experiments.

  13. Improving aqueous solubility and antitumor effects by nanosized gambogic acid-mPEG2000 micelles

    Directory of Open Access Journals (Sweden)

    Cai LL

    2013-12-01

    Full Text Available Lulu Cai,1,* Neng Qiu,2,* Mingli Xiang,3,* Rongsheng Tong,1 Junfeng Yan,1 Lin He,1 Jianyou Shi,1 Tao Chen,4 Jiaolin Wen,3 Wenwen Wang,3 Lijuan Chen31Department of Pharmacy, Sichuan Academy of Medical Science and Sichuan Provincial People's Hospital, 2College of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, 3State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu, People's Republic of China; 4Faculty of Pharmacy, University of Montreal, Montreal, QC, Canada *These authors contributed equally to this paperAbstract: The clinical application of gambogic acid, a natural component with promising antitumor activity, is limited due to its extremely poor aqueous solubility, short half-life in blood, and severe systemic toxicity. To solve these problems, an amphiphilic polymer-drug conjugate was prepared by attachment of low molecular weight (ie, 2 kDa methoxy poly(ethylene glycol methyl ether (mPEG to gambogic acid (GA-mPEG2000 through an ester linkage and characterized by 1H nuclear magnetic resonance. The GA-mPEG2000 conjugates self-assembled to form nanosized micelles, with mean diameters of less than 50 nm, and a very narrow particle size distribution. The properties of the GA-mPEG2000 micelles, including morphology, stability, molecular modeling, and drug release profile, were evaluated. MTT (3-(4,5-dimethylthiazol-2-yl-2,5 diphenyl tetrazolium bromide tests demonstrated that the GA-mPEG2000 micelle formulation had obvious cytotoxicity to tumor cells and human umbilical vein endothelial cells. Further, GA-mPEG2000 micelles were effective in inhibiting tumor growth and prolonged survival in subcutaneous B16-F10 and C26 tumor models. Our findings suggest that GA-mPEG2000 micelles may have promising applications in tumor therapy.Keywords: gambogic acid, poly(ethylene glycol-drug conjugate, micelle, antitumor, toxicity

  14. Supersaturation induced by Itraconazole/Soluplus® micelles provided high GI absorption in vivo

    Directory of Open Access Journals (Sweden)

    Yue Zhong

    2016-04-01

    Full Text Available To investigate the effect of supersaturation induced by micelle formation during dissolution on the bioavailability of itraconazole (ITZ/Soluplus® solid dispersion. Solid dispersions prepared by hot melt extrusion (HME were compressed into tablets directly with other excipients. Dissolution behavior of ITZ tablets was studied by dissolution testing and the morphology of micelles in dissolution media was studied using transmission electron microscopy (TEM. Drug transferring from stomach into intestine was simulated to obtain a supersaturated drug solution. Bioavailability studies were performed on the ITZ tablets and Sporanox® in beagle dogs. The morphology of micelles in the dissolution media was observed to be spherical in shape, with an average size smaller than 100 nm. The supersaturated solutions formed by Soluplus® micelles were stable and no precipitation took place over a period of 180 min. Compared with Sporanox®, ITZ tablets exhibited a 2.50-fold increase in the AUC(0–96 of ITZ and a 1.95-fold increase in its active metabolite hydroxyitraconazole (OH-ITZ in the plasma of beagle dogs. The results obtained provided clear evidence that not only the increase in the dissolution rate in the stomach, but also the supersaturation produced by micelles in the small intestine may be of great assistance in the successful development of poorly water-soluble drugs. The micelles formed by Soluplus® enwrapped the molecular ITZ inside the core which promoted the amount of free drug in the intestinal cavity and carried ITZ through the aqueous boundary layer (ABL, resulting in high absorption by passive transportation across biological membranes. The uptake of intact micelles through pinocytosis together with the inhibition of P-glycoprotein-mediated drug efflux in intestinal epithelia contributed to the absorption of ITZ in the gastrointestinal tract. These results indicate that HME with Soluplus®, which can induce supersaturation by micelle

  15. 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...... 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...

  16. Polymeric micelles for drug delivery : from synthesis to in vivo studies

    NARCIS (Netherlands)

    Shi, Yang

    2014-01-01

    Drug delivery systems have been extensively utilized to increase water-solubility of hydrophobic chemotherapeutic drugs and target the drugs to tumors, which enhances the efficacy of chemotherapy and simultaneously decreases non-specific disposition of cytostatic drugs in healthy organ/tissues, and

  17. Enhanced effect of folated pluronic F87-PLA/TPGS mixed micelles on targeted delivery of paclitaxel.

    Science.gov (United States)

    Xiong, Xiang Yuan; Pan, Xiaoqian; Tao, Long; Cheng, Feng; Li, Zi Ling; Gong, Yan Chun; Li, Yu Ping

    2017-10-01

    Targeted drug delivery systems have great potential to overcome the side effect and improve the bioavailability of conventional anticancer drugs. In order to further improve the antitumor efficacy of paclitaxel (PTX) loaded in folated Pluronic F87/poly(lactic acid) (FA-F87-PLA) micelles, D-α-tocopheryl poly(ethylene glycol) 1000 succinate (TPGS or Vitamin E TPGS) were added into FA-F87-PLA to form FA-F87-PLA/TPGS mixed micelles. The LE of PTX-loaded mixed micelles (13.5%) was highest in the mass ratio 5 to 3 of FA-F87-PLA to TPGS. The in vitro cytotoxicity assays indicated that the IC50 values for free PTX injections, PTX-loaded FA-F87-PLA micelles and PTX-loaded FA-F87-PLA/TPGS mixed micelles after 72h of incubation were 1.52, 0.42 and 0.037mg/L, respectively. The quantitative cellular uptake of coumarin 6-loaded FA-F87-PLA/TPGS and FA-F87-PLA micelles showed that the cellular uptake efficiency of mixed micelles was higher for 2 and 4h incubation, respectively. In vivo pharmacokinetic studies found that the AUC of PTX-loaded FA-F87-PLA/TPGS mixed micelles is almost 1.4 times of that of PTX-loaded FA-F87-PLA micelles. The decreased particle size and inhibition of P-glycoprotein effect induced by the addition of TPGS could result in enhancing the cellular uptake and improving the antitumor efficiency of PTX-loaded FA-F87-PLA/TPGS mixed micelles. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. RAFT Synthesis and Self-Assembly of Free-Base Porphyrin Cored Star Polymers

    Directory of Open Access Journals (Sweden)

    Lin Wu

    2011-01-01

    Full Text Available Reversible addition fragmentation chain transfer (RAFT synthesis and self-assembly of free-base porphyrin cored star polymers are reported. The polymerization, in the presence of a free-base porphyrin cored chain transfer agent (CTA-FBP, produced porphyrin star polymers with controlled molecular weights and narrow polydispersities for a number of monomers including N, N-dimethylacrylamide (DMA and styrene (St. Well-defined amphiphilic star block copolymers, P-(PS-PDMA4 and P-(PDMA-PS4 (P: porphyrin, were also prepared and used for self-assembly studies. In methanol, a selective solvent for PDMA, spherical micelles were observed for both block copolymers as characterized by TEM. UV-vis studies suggested star-like micelles were formed from P-(PS-PDMA4, while P-(PDMA-PS4 aggregated into flower-like micelles. Spectrophotometric titrations indicated that the optical response of these two micelles to external ions was a function of micellar structures. These structure-related properties will be used for micelle studies and functional material development in the future.

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

    Directory of Open Access Journals (Sweden)

    Ana Maria Frattini Fileti

    2009-10-01

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

  20. DNA-Based Identification and Chemical Characteristics of Hypnea musciformis from Coastal Sites in Ghana

    Directory of Open Access Journals (Sweden)

    Marcel Tutor Ale

    2016-06-01

    Full Text Available This work reveals new, important insights about the influence of broad spatial variations on the phylogenetic relationship and chemical characteristics of Ghanaian Hypnea musciformis—a carrageenan-containing red seaweed. DNA barcoding techniques alleviate the difficulty for accurate morphological identification. COI barcode sequences of the Ghanaian H. musciformis showed <0.7% intraspecies divergence, indicating no distinct phylogenetic variation, suggesting that they actually belong to the same species. Thus, the spatial distribution of the sampling sites along the coast of Ghana did not influence the phylogenetic characteristics of H. musciformis in the region. The data also showed that the Ghanaian Hypnea sp. examined in this work should be regarded as the same species as the H. musciformis collected in Brazilian Sao Paulo (KP725276 with only 0.8%–1.3% intraspecies divergence. However, the comparison of COI sequences of Ghanaian H. musciformis with the available COI sequence of H. musciformis from other countries showed intraspecies divergences of 0%–6.9% indicating that the COI sequences for H. musciformis in the GenBank may include different subspecies. Although samples did not differ phylogenetically, the chemical characteristics of the H. musciformis differed significantly between different sampling locations in Ghana. The levels of the monosaccharides, notably galactose (20%–30% dw and glucose (10%–18% dw, as well as the seawater inorganic salt concentration (21–32 mg/L and ash content (19%–33% dw, varied between H. musciformis collected at different coastal locations in Ghana. The current work demonstrated that DNA-based identification allowed a detailed understanding of H. musciformis phylogenetic characteristics and revealed that chemical compositional differences of H. musciformis occur along the Ghanaian coast which are not coupled with genetic variations among those samples.

  1. Perceptions of genetic testing for personalized nutrition: a randomized trial of DNA-based dietary advice.

    Science.gov (United States)

    Nielsen, Daiva E; Shih, Sarah; El-Sohemy, Ahmed

    2014-01-01

    Direct-to-consumer (DTC) genetic tests have facilitated easy access to personal genetic information related to health and nutrition; however, consumer perceptions of the nutritional information provided by these tests have not been evaluated. The objectives of this study were to assess individual perceptions of personalized nutrition and genetic testing and to determine whether a personalized nutrition intervention modifies perceptions. A double-blind, parallel-group, randomized controlled trial was conducted among healthy men and women aged 20-35 years (n = 138). Participants in the intervention group (n = 92) were given a report of DNA-based dietary advice and those in the control group (n = 46) were given a general dietary advice report. A survey was completed at baseline and 3 and 12 months after distributing the reports to assess perceptions between the two groups. No significant differences in perceptions of personalized nutrition and genetic testing were observed between the intervention and control group, so responses of both groups were combined. As compared to baseline, participant responses increased significantly toward the positive end of a Likert scale at 3 months for the statement 'I am interested in the relationship between diet and genetics' (mean change ± SD: 0.28 ± 0.99, p = 0.0002). The majority of participants indicated that a university research lab (47%) or health care professional (41%) were the best sources for obtaining accurate personal genetic information, while a DTC genetic testing company received the fewest selections (12%). Most participants (56%) considered dietitians to be the best source of personalized nutrition followed by medical doctors (27%), naturopaths (8%) and nurses (6%). These results suggest that perceptions of personalized nutrition changed over the course of the intervention. Individuals view a research lab or health care professional as better providers of genetic information than a DTC genetic testing company

  2. Genomic DNA-based absolute quantification of gene expression in Vitis.

    Science.gov (United States)

    Gambetta, Gregory A; McElrone, Andrew J; Matthews, Mark A

    2013-07-01

    Many studies in which gene expression is quantified by polymerase chain reaction represent the expression of a gene of interest (GOI) relative to that of a reference gene (RG). Relative expression is founded on the assumptions that RG expression is stable across samples, treatments, organs, etc., and that reaction efficiencies of the GOI and RG are equal; assumptions which are often faulty. The true variability in RG expression and actual reaction efficiencies are seldom determined experimentally. Here we present a rapid and robust method for absolute quantification of expression in Vitis where varying concentrations of genomic DNA were used to construct GOI standard curves. This methodology was utilized to absolutely quantify and determine the variability of the previously validated RG ubiquitin (VvUbi) across three test studies in three different tissues (roots, leaves and berries). In addition, in each study a GOI was absolutely quantified. Data sets resulting from relative and absolute methods of quantification were compared and the differences were striking. VvUbi expression was significantly different in magnitude between test studies and variable among individual samples. Absolute quantification consistently reduced the coefficients of variation of the GOIs by more than half, often resulting in differences in statistical significance and in some cases even changing the fundamental nature of the result. Utilizing genomic DNA-based absolute quantification is fast and efficient. Through eliminating error introduced by assuming RG stability and equal reaction efficiencies between the RG and GOI this methodology produces less variation, increased accuracy and greater statistical power. © 2012 Scandinavian Plant Physiology Society.

  3. A DNA-based registry for all animal species: the barcode index number (BIN system.

    Directory of Open Access Journals (Sweden)

    Sujeevan Ratnasingham

    Full Text Available Because many animal species are undescribed, and because the identification of known species is often difficult, interim taxonomic nomenclature has often been used in biodiversity analysis. By assigning individuals to presumptive species, called operational taxonomic units (OTUs, these systems speed investigations into the patterning of biodiversity and enable studies that would otherwise be impossible. Although OTUs have conventionally been separated through their morphological divergence, DNA-based delineations are not only feasible, but have important advantages. OTU designation can be automated, data can be readily archived, and results can be easily compared among investigations. This study exploits these attributes to develop a persistent, species-level taxonomic registry for the animal kingdom based on the analysis of patterns of nucleotide variation in the barcode region of the cytochrome c oxidase I (COI gene. It begins by examining the correspondence between groups of specimens identified to a species through prior taxonomic work and those inferred from the analysis of COI sequence variation using one new (RESL and four established (ABGD, CROP, GMYC, jMOTU algorithms. It subsequently describes the implementation, and structural attributes of the Barcode Index Number (BIN system. Aside from a pragmatic role in biodiversity assessments, BINs will aid revisionary taxonomy by flagging possible cases of synonymy, and by collating geographical information, descriptive metadata, and images for specimens that are likely to belong to the same species, even if it is undescribed. More than 274,000 BIN web pages are now available, creating a biodiversity resource that is positioned for rapid growth.

  4. DNA-based prediction of human externally visible characteristics in forensics: motivations, scientific challenges, and ethical considerations.

    Science.gov (United States)

    Kayser, Manfred; Schneider, Peter M

    2009-06-01

    There will always be criminal cases, where the evidence DNA sample will not match either a suspect's DNA profile, or any in a criminal DNA database. In the absence of DNA-based mass intelligence screenings, including familial searching (both of which may be restricted by legislation), there is only one option to potentially avoid or retrospectively solve "cold cases": the DNA-based prediction of human externally visible characteristics of an unknown person based on the crime scene sample left behind. Predictive DNA markers are expected to be available for some group-specific appearance traits in the near future; although it is unlikely that we will soon be able to understand the biological complexity of individual-specific appearance. In suspect-less cases reliable DNA-based prediction of broader externally visible characteristics from crime scene samples are expected to reduce the potential pool of suspects by allowing police investigations to concentrate on specific groups of people. Here, we aim to describe the forensic motivations for DNA-based prediction of human externally visible traits as well as the scientific challenges of finding predictive DNA markers, and will discuss examples with promising (e.g. sex, eye color and hair color), as well as less promising expectations (e.g. adult body height), in the foreseen future. Despite the complex ethical and legal implications arising from DNA-based prediction of externally visible characteristics, we argue that their use does not lead to a violation of privacy. We suggest that likelihood-based results, rather than DNA data itself, should be provided to the police for investigative purposes avoiding data protection issues. Furthermore, we note that the risk of exacerbating social pressure on minority groups due to DNA-based prediction of externally visible traits in crime cases may be reduced rather than increased compared to a conventional eyewitness testimony. A firm legal basis will need to be established for

  5. The structure of P85 pluronic block copolymer micelles determined by small-angle neutron scattering

    DEFF Research Database (Denmark)

    Pedersen, J.S.; Gerstenberg, M.C.

    2003-01-01

    a spherical core of poly(propylene oxide) (PPO) with some water surrounded by a corona of the poly(ethylene oxide) (PEO) block. The latter are non-interacting and obey Gaussian statistics, but are expelled from the core region. The analysis shows that the micelles are fairly concentration and temperature...

  6. Shape-designed single-polymer micelles: a proof-of-concept simulation

    Science.gov (United States)

    Moths, Brian; Witten, Thomas A.

    Much effort has been directed towards self-assembling nanostructures. Strong, local interactions between specific building blocks often determine these structures (e.g., globular proteins). We seek to produce designed structures that are instead determined by collective effects of weak interactions (e.g., surfactant self-assembly). Such structures may reversibly change conformation or disassemble in response to changing solvent conditions, and, being soft, have potential to adapt to fluctuating or unknown application-imposed shape requirements. Concretely, we aim to realize such a structure in the form of a single polymer micelle--an amphiphilic polymer exhibiting a condensed, phase-segregated conformation when immersed in solvent. Connecting all amphiphiles into a single chain provides geometric constraints controlling the surface curvature profile, thus dictating a non-trivial shape. We present 2D Monte Carlo simulation results demonstrating the feasibility of such soft, shape-designed micelles. Preliminary results demonstrate a stable concave ``dimple'' in a micelle composed of a single A-B multiblock linear copolymer. We discuss both current limitations on shape robustness and effects of block asymmetry, block molecular weights and overall chain length on micelle shape. This work was supported in part by the National Science Foundation's MRSEC Program under Award Number DMR-1420709.

  7. Molecular variations in aromatic cosolutes: critical role in the rheology of cationic wormlike micelles.

    Science.gov (United States)

    Ito, Thiago H; Miranda, Paulo C M L; Morgon, Nelson H; Heerdt, Gabriel; Dreiss, Cécile A; Sabadini, Edvaldo

    2014-10-07

    Wormlike micelles formed by the addition to cetyltrimethylammonium bromide (CTAB) of a range of aromatic cosolutes with small molecular variations in their structure were systematically studied. Phenol and derivatives of benzoate and cinnamate were used, and the resulting mixtures were studied by oscillatory, steady-shear rheology, and the microstructure was probed by small-angle neutron scattering. The lengthening of the micelles and their entanglement result in remarkable viscoelastic properties, making rheology a useful tool to assess the effect of structural variations of the cosolutes on wormlike micelle formation. For a fixed concentration of CTAB and cosolute (200 mmol L(-1)), the relaxation time decreases in the following order: phenol > cinnamate> o-hydroxycinnamate > salicylate > o-methoxycinnamate > benzoate > o-methoxybenzoate. The variations in viscoelastic response are rationalized by using Mulliken population analysis to map out the electronic density of the cosolutes and quantify the barrier to rotation of specific groups on the aromatics. We find that the ability of the group attached to the aromatic ring to rotate is crucial in determining the packing of the cosolute at the micellar interface and thus critically impacts the micellar growth and, in turn, the rheological response. These results enable us for the first time to propose design rules for the self-assembly of the surfactants and cosolutes resulting in the formation of wormlike micelles with the cationic surfactant CTAB.

  8. Block and Gradient Copoly(2-oxazoline) Micelles: Strikingly Different on the Inside.

    Science.gov (United States)

    Filippov, Sergey K; Verbraeken, Bart; Konarev, Petr V; Svergun, Dmitri I; Angelov, Borislav; Vishnevetskaya, Natalya S; Papadakis, Christine M; Rogers, Sarah; Radulescu, Aurel; Courtin, Tim; Martins, José C; Starovoytova, Larisa; Hruby, Martin; Stepanek, Petr; Kravchenko, Vitaly S; Potemkin, Igor I; Hoogenboom, Richard

    2017-08-17

    Herein, we provide a direct proof for differences in the micellar structure of amphiphilic diblock and gradient copolymers, thereby unambiguously demonstrating the influence of monomer distribution along the polymer chains on the micellization behavior. The internal structure of amphiphilic block and gradient co poly(2-oxazolines) based on the hydrophilic poly(2-methyl-2-oxazoline) (PMeOx) and the hydrophobic poly(2-phenyl-2-oxazoline) (PPhOx) was studied in water and water-ethanol mixtures by small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS), static and dynamic light scattering (SLS/DLS), and 1 H NMR spectroscopy. Contrast matching SANS experiments revealed that block copolymers form micelles with a uniform density profile of the core. In contrast to popular assumption, the outer part of the core of the gradient copolymer micelles has a distinctly higher density than the middle of the core. We attribute the latter finding to back-folding of chains resulting from hydrophilic-hydrophobic interactions, leading to a new type of micelles that we refer to as micelles with a "bitterball-core" structure.

  9. The pressure-induced, lactose-dependent changes in the composition and size of casein micelles.

    Science.gov (United States)

    Wang, Pengjie; Jin, Shaoming; Guo, Huiyuan; Zhao, Liang; Ren, Fazheng

    2015-04-15

    The effects of lactose on the changes in the composition and size of casein micelles induced by high-pressure treatment and the related mechanism of action were investigated. Dispersions of ultracentrifuged casein micelle pellets with 0-10% (w/v) lactose were subjected to high pressure (400 MPa) at 20 °C for 40 min. The results indicated that the level of non-sedimentable caseins was positively related to the amount of lactose added prior to pressure treatment, and negatively correlated to the size. A mechanism for the pressure-induced, lactose-dependent changes in the casein micelles is proposed. Lactose inhibits the hydrophobic interactions between the micellar fragments during or after pressure release, through the hydrophilic layer formed by their hydrogen bonds around the micellar fragments. In addition, lactose does not favour the association between calcium and the casein aggregates after pressure release. Due to these two functions, lactose inhibited the formation of larger micelles after pressure treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Preventing Small Molecule Nucleation and Crystallization by Sequestering in a Micelle Corona

    Science.gov (United States)

    Li, Ziang; Johnson, Lindsay; Ricarte, Ralm; Yao, Letitia; Hillmyer, Marc; Bates, Frank; Lodge, Timothy

    We exploited a blend of hydroxypropyl methylcellulose acetate succinate and poly(N-isopropylacrylamide) (PNIPAm) to improve the solubility and dissolution of a rapidly crystallizing model drug molecule phenytoin and observed synergistic effect in vitro at constant drug loading by varying the blending ratio. Dynamic and static light scattering experiments showed that PNIPAm self-assembled into micelles in aqueous solution. We believe that adding these PNIPAm micelles inhibited both nucleation and crystal growth of phenytoin based on the polarized light micrographs taken from the dissolution media. The drug-polymer intermolecular interaction was revealed by nuclear Overhauser effect spectroscopy and further quantified by diffusion ordered spectroscopy. We found that the phenytoin molecules were sequestered in aqueous solution by partitioning into the corona of the micelle. The blend strategy through the use of self-assembled micelles showcased in this study offers a new platform for designing advanced excipients for oral drug delivery. This study was funded by The Dow Chemical Company through Agreement 224249AT with the University of Minnesota.

  11. Micelle-Mediated Extraction and Cloud Point Pre-concentration for ...

    African Journals Online (AJOL)

    NICO

    Micelle-Mediated Extraction and Cloud Point. Pre-concentration for the Spectrophotometric. Determination of Phenol in Water Samples. Ali Reza Zarei*, Forouzan Gholamian and Soheila Chalavi. Department of Chemistry, Faculty of Materials, Malek Ashtar University of Technology, Tehran, Iran. Received 6 September ...

  12. Terbium Functionalized Micelle Nanoprobe for Ratiometric Fluorescence Detection of Anthrax Spore Biomarker.

    Science.gov (United States)

    Luan, Ke; Meng, Ruiqian; Shan, Changfu; Cao, Jing; Jia, Jianguo; Liu, Weisheng; Tang, Yu

    2018-03-06

    Rapid, sensitive, and selective quantitative detection of pyridine dicarboxylic acid (DPA) as biomarker of anthrax spores is in great demand since anthrax spores are highly lethal to human beings and animals and also potential biological warfare agents. Herein, we prepared a ratiometric fluorescence lanthanide functionalized micelle nanoprobe by "one-pot" self-assembly, with an amphiphilic ligand containing β-diketone derivative which can "immobilize" terbium ions through the coordination interaction and a fluorophore as fluorescence reference (FR). The detection strategy was ascribed to Tb 3+ ions in lanthanide functionalized micelle, which can be sensitized to emit the intrinsic luminescence upon addition of DPA due to the presence of energy transfer when DPA chromophore coordinated with Tb 3+ ion. The fluorescence intensity of FR remained essentially constant, leading to ratiometric fluorescence response toward DPA. The results demonstrate that the terbium functionalized micelle was able to sensitively detect DPA with a linear relation in the range of 0 μM to 7.0 μM in aqueous solution, which also showed remarkable selectivity to DPA over other aromatic ligands. Our work paves a new way in the design of ratiometric fluorescence lanthanide functionalized micelle nanoprobes which can be promising for selective and sensitive detection of bacterial spores or biomolecules.

  13. Hydrolytically degradable polymer micelles for drug delivery: a SAXS/SANS kinetic study

    Czech Academy of Sciences Publication Activity Database

    Filippov, Sergey K.; Franklin, J. M.; Konarev, P. V.; Chytil, Petr; Etrych, Tomáš; Bogomolova, Anna; Dyakonova, M.; Papadakis, C. M.; Radulescu, A.; Ulbrich, Karel; Štěpánek, Petr; Svergun, D. I.

    2013-01-01

    Roč. 14, č. 11 (2013), s. 4061-4070 ISSN 1525-7797 R&D Projects: GA ČR GAP208/10/1600 Institutional support: RVO:61389013 Keywords : HPMA * micelles * drug release Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.788, year: 2013

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

    International Nuclear Information System (INIS)

    Friedrich, Leidi C.; Silva, Volnir O.; Quina, Frank H.; Moreira Junior, Paulo F.; Tcacenco, Celize M.

    2013-01-01

    Aggregation numbers (N 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 (γ = 0.11-0.15, where γ is the slope of a plot of log aggregation number vs. log [Y aq ] and [Y 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 (γ ca. 0.25), a difference attributed to the larger headgroup size of SLES. The I 1 /I 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)

  15. 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)

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

    Directory of Open Access Journals (Sweden)

    Adina Roxana Petcu

    2016-01-01

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

  17. Photoenhanced gene transfection by a curcumin loaded CS-g-PZLL micelle.

    Science.gov (United States)

    Lin, Jian-Tao; Pan, Wen-Jia; Zhang, Jun-Ai; Wang, Wei; Zhong, Jia; Su, Jia-Min; Li, Tong; Zou, Ying; Wang, Guan-Hai

    2017-09-01

    The codelivery of drug and gene is a promising method for cancer treatment. In our previous works, we prepared a cationic micelles based on chitosan and poly-(N-3-carbobenzyloxylysine) (CS-g-PZLL), but transfection ratio of CS-g-PZLL to Hela cell was low. Herein, to improve the transfection efficiency of CS-g-PZLL, curcumin was loaded in the CS-g-PZLL micelle. After irradiation, the obtained curcumin loaded micelle showed a better transfection, and the p53 protein expression in Hela cells was higher. The apoptosis assay showed that the complex could induce a more significant apoptosis to Hela cells than that of curcumin or p53 used alone, and the curcumin loaded micelle inducing apoptosis was best after irradiation. Therefore, CS-g-PZLL is a safe and effective carrier for the codelivery of drug/gene, and curcumin could be used as a photosensitizer to induce a photoenhanced gene transfection, which should be encouraged in improving transfection and tumor therapy. Copyright © 2017. Published by Elsevier B.V.

  18. Corrosion Performance of Carbon Steel in Simulated Pore Solution in the Presence of Micelles

    NARCIS (Netherlands)

    Hu, J.; Koleva, D.A.; De Wit, J.H.W.; Kolev, H.; Van Breugel, K.

    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

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  20. Micelles versus Ribbons: How Congeners Drive the Self-Assembly of Acidic Sophorolipid Biosurfactants.

    Science.gov (United States)

    Dhasaiyan, Prabhu; Le Griel, Patrick; Roelants, Sophie; Redant, Emile; Van Bogaert, Inge N A; Prevost, Sylvain; Prasad, B L V; Baccile, Niki

    2017-03-17

    Sophorolipids (SLs), a class of microbially derived biosurfactants, are reported by different research groups to have different self-assembled structures (either micelles or giant ribbons) under the same conditions. Here we explore the reasons behind these contradictory results and attribute these differences to the role of specific congeners that are present in minute quantities. We show that a sample composed of a majority of oleic acid (C18:1) sophorolipid in the presence of only 0.5 % (or more) of congeners with stearic acid (C18:0) or linoleic acid (C18:2) results in the formation of micelles that are stable over long periods of time. Conversely, the presence of only 10 to 15 % of congeners with a stearic acid chain gives fibrillar structures instead of micelles. To study the mechanisms responsible, oleic acid SLs devoid of any other congeners were prepared. Very interestingly, this sample can self-assemble into either micelles or fibers depending on minute modifications to the self-assembly conditions. The findings are supported by light scattering, small-angle X-ray scattering, transmission electron microscopy under cryogenic conditions, high-pressure liquid chromatography, and NMR spectroscopy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. An application of micelle solubilization spectrophotometry in the determination of thorium

    International Nuclear Information System (INIS)

    Peng Changhai; Zeng Xiaoming

    1988-01-01

    In this review article the characteristics of the analytical method of Th by means of micelle solubilization spectrophotometry are described and the mechanism of the solubilization and chemical reactions involved is discussed. Also the various color-developing reagents that have been used for this determination are described and compared

  2. Detergent properties influence the stability of the glycophorin A transmembrane helix dimer in lysophosphatidylcholine micelles.

    Science.gov (United States)

    Stangl, Michael; Veerappan, Anbazhagan; Kroeger, Anja; Vogel, Peter; Schneider, Dirk

    2012-12-19

    Detergents might affect membrane protein structures by promoting intramolecular interactions that are different from those found in native membrane bilayers, and fine-tuning detergent properties can be crucial for obtaining structural information of intact and functional transmembrane proteins. To systematically investigate the influence of the detergent concentration and acyl-chain length on the stability of a transmembrane protein structure, the stability of the human glycophorin A transmembrane helix dimer has been analyzed in lyso-phosphatidylcholine micelles of different acyl-chain length. While our results indicate that the transmembrane protein is destabilized in detergents with increasing chain-length, the diameter of the hydrophobic micelle core was found to be less crucial. Thus, hydrophobic mismatch appears to be less important in detergent micelles than in lipid bilayers and individual detergent molecules appear to be able to stretch within a micelle to match the hydrophobic thickness of the peptide. However, the stability of the GpA TM helix dimer linearly depends on the aggregation number of the lyso-PC detergents, indicating that not only is the chemistry of the detergent headgroup and acyl-chain region central for classifying a detergent as harsh or mild, but the detergent aggregation number might also be important. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  3. Isomerization of Orthogonal Molecular Switches Encapsulated within Micelles Solubilizing Carbon Nanotubes

    DEFF Research Database (Denmark)

    Kreft, Stefanie K.; Petersen, Michael Åxman; Nielsen, Mogens Brøndsted

    2015-01-01

    We study the effects of the proximity of the orthogonal dipole-switching moiety dihydroazulene/vinylheptafulvene (DHA/VHF) to carbon nanotubes (CNTs). The switches are introduced into a micelle surrounding the CNTs, thereby achieving very close proximity between the molecules and the CNTs...... of the CNTs and the resulting reversible redshift of the nanotubes' emission by the change of the molecules' conformation....

  4. Effect of Admixed Micelles on the Microstructure Alterations of Reinforced Mortar Subjected to Chloride Induced Corrosion

    NARCIS (Netherlands)

    Hu, J.; Koleva, D.A.; Van Breugel, K.

    2011-01-01

    This paper reports the main results from the influence of the initially admixed nano-aggregates (0.5 g/l PEO113-b-PS70 micelles previously dissolved in demi-water) on microstructural alterations of the reinforced mortar subjected to chloride induced corrosion. The morphology of hydration/corrosion

  5. Novel Brassinosteroid-Modified Polyethylene Glycol Micelles for Controlled Release of Agrochemicals.

    Science.gov (United States)

    Pérez Quiñones, Javier; Brüggemann, Oliver; Kjems, Jørgen; Shahavi, Mohammad Hassan; Peniche Covas, Carlos

    2018-02-21

    Two synthetic analogues of brassinosteroids (DI31 and S7) exhibit good plant growth enhancer activity. However, their hydrophobicity and quick metabolism in plants have limited their application and benefits in agriculture. Our objective was to prepare novel brassinosteroid-modified polyethylene glycol (PEG) micelles to achieve controlled release with extended stability while retaining agrochemical activity. Spectroscopic studies confirmed quantitative disubstitution of studied PEGs with the brassinosteroids, while elemental analysis assessed purity of the synthesized conjugates. Conjugates were also characterized by X-ray diffraction and thermal analysis. Dynamic and static light scattering showed stable and homogeneous approximately spherical micelles with average hydrodynamic diameters of 22-120 nm and almost neutral ζ potential. Spherical 30-140 nm micelles were observed by electron microscopy. Sustained in vitro releases at pH 5.5 were extended up to 96 h. Prepared PEG micelles showed good agrochemical activity in the radish seed bioassay and no cytotoxicity to the human microvascular endothelial cell line in the MTS test.

  6. Light scattering evidence of selective protein fouling on biocompatible block copolymer micelles

    Czech Academy of Sciences Publication Activity Database

    Giacomelli, F. C.; Štěpánek, Petr; Schmidt, V.; Jäger, Eliezer; Jäger, Alessandro; Giacomelli, C.

    2012-01-01

    Roč. 4, č. 15 (2012), s. 4504-4514 ISSN 2040-3364 R&D Projects: GA ČR GAP208/10/1600 Institutional research plan: CEZ:AV0Z40500505 Keywords : copolymer micelles * protein fouling * light scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.233, year: 2012

  7. Internal structural characterization of triblock copolymer micelles with looped corona chains

    Czech Academy of Sciences Publication Activity Database

    Giacomelli, F. C.; Riegel, I. C.; Petzhold, C. L.; Silveira, N.; Štěpánek, Petr

    2009-01-01

    Roč. 25, č. 6 (2009), s. 3487-3493 ISSN 0743-7463 R&D Projects: GA ČR GA202/09/2078 Institutional research plan: CEZ:AV0Z40500505 Keywords : block copolymers * micelles * angle neutron - scattering Subject RIV: BO - Biophysics Impact factor: 3.898, year: 2009

  8. Cylindrical micelles of a POSS amphiphilic dendrimer as nano-reactors for polymerization.

    Science.gov (United States)

    Weng, Jing-Ting; Yeh, Tso-Fan; Samuel, Ashok Zachariah; Huang, Yi-Fan; Sie, Jyun-Hao; Wu, Kuan-Yi; Peng, Chi-How; Hamaguchi, Hiro-O; Wang, Chien-Lung

    2018-02-15

    A low generation amphiphilic dendrimer, POSS-AD, which has a POSS core and eight amphiphilic arms, was synthesized and used as a nano-reactor to produce well-defined polymer nano-cylinders. Confirmed by small-angle X-ray scattering (SAXS), Raman and NMR spectrometry, monodispersed cylindrical micelles that contain a hydrophilic cavity with a diameter of 2.09 nm and a length of 4.26 nm were produced via co-assembling POSS-AD with hydrophilic liquids, such as H 2 O and HEMA in hydrophobic solvents. Taking the HEMA/POSS-AD cylindrical micelles as nano-reactors, polymerization of HEMA within the micelles results in polymer nano-cylinders (POSS-ADNPs) with a diameter of 2.24 nm and a length of 5.02 nm. The study confirmed that despite the inability to maintain specific shape in solution, low generation dendrimers form well-defined nano-containers or nano-reactors, which relies on co-assembling with hydrophilic guest molecules. These nano-reactors are robust enough to maintain their shape during the polymerization of the guest molecules. Polymer nano-cylinders with dimensions less than 10 nm can thus be produced from the HEMA/POSS-AD micelles. Since the chemical structure of low-generation dendrimers and the contents of the co-assembled nano-reactors can be easily adjusted, the concept holds the potential for the further developments of low-generation amphiphilic dendrimers.

  9. Salt-Induced Disintegration of Lysozyme-Containing Polyelectrolyte Complex Micelles

    NARCIS (Netherlands)

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

    2009-01-01

    The salt-induced disintegration of lysozyme-filled polyelectrolyte complex micelles, consisting of positively charged homopolymers (PDMAEMA(150)), negatively charged diblock copolymers (PAA(42)-PAAm(417)) and lysozyme, has been Studied with dynamic light scattering (DL) and small-angle neutron

  10. Salt-Induced Disintegration of Lysozyme-Containing Polyelectrolyte Complex Micelles

    NARCIS (Netherlands)

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

    2009-01-01

    The salt-induced disintegration of lysozyme-filled polyelectrolyte complex micelles, consisting of positively charged homopolymers (PDMAEMA150), negatively charged diblock copolymers (PAA42-PAAm417), and lysozyme, has been studied with dynamic light scattering (DLS) and small-angle neutron

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

    Indian Academy of Sciences (India)

    Small-angle neutron scattering (SANS) measurements were carried out on sodium dodecyl sulfate (SDS) micelles in the presence of three different hydrophobic salts, ... Novel Materials and Structural Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India; Solid State Physics Division, Bhabha Atomic ...

  12. RELATION BETWEEN SURFACTANT STRUCTURE AND PROPERTIES OF SPHERICAL MICELLES - 1-ALKYL-4-ALKYLPYRIDINIUM HALIDE SURFACTANTS

    NARCIS (Netherlands)

    NUSSELDER, JJH; ENGBERTS, JBFN

    1991-01-01

    This paper describes a detailed study of the properties of spherical micelles formed from 18 1-alkyl-4-alkylpyridinium iodides. Structural variations in the surfactants include (i) branching of the 4-alkyl chain while keeping the number of carbons in the chain invariant and (ii) variation of the

  13. Analysis of small-angle scattering data from micelles and microemulsions

    DEFF Research Database (Denmark)

    Pedersen, J.S.

    1999-01-01

    The free-form methods for analyzing small-angle scattering data have, during the last years, found more widespread use for micelles and microemulsions. Recent developments have made them applicable also to systems with size polydispersity and particle correlations, however, model fitting still...

  14. Study of the emission oxidative reactions of ruthenium (II) complex by cationic compounds in anionic micelles

    International Nuclear Information System (INIS)

    Bonilha, J.B.S.

    1985-01-01

    The oxidative quenching of the emission of the tetraanionic complex tris (4,4' dicarboxylate - 2,2' - bipyridine ruthenium (II) in aqueous solution, by both organic and inorganic compounds in presence of anionic detergents, above and below the critical micelle concentration is studied. The organic cations, the inorganic ion and detergents used are shown. (M.J.C.) [pt

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

    International Nuclear Information System (INIS)

    Shrestha, Lok Kumar; Aramaki, Kenji

    2009-01-01

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

  16. The Production of Nanoparticulate Ceria Using Reverse Micelle Sol-Gel Techniques

    Czech Academy of Sciences Publication Activity Database

    Mason, S.; Holliman, P.; Kalaji, M.; Klusoň, Petr

    2009-01-01

    Roč. 19, č. 21 (2009), s. 3517-3522 ISSN 0959-9428 Institutional research plan: CEZ:AV0Z40720504 Keywords : ceria * reverse micelles * alkoxide Subject RIV: CC - Organic Chemistry Impact factor: 4.795, year: 2009

  17. Thermodynamic profiling of Peptide membrane interactions by isothermal titration calorimetry: a search for pores and micelles

    DEFF Research Database (Denmark)

    Henriksen, Jonas Rosager; Andresen, Thomas Lars

    2011-01-01

    in mixed peptide-lipid micelles. We have investigated the mode of action of the antimicrobial peptide mastoparan-X using isothermal titration calorimetry (ITC) and cryo-transmission electron microscopy (cryo-TEM). The results show that mastoparan-X induces a range of structural transitions of POPC/POPG (3...

  18. CTAB/water/chloroform reverse micelles: a closed or open association model?

    Czech Academy of Sciences Publication Activity Database

    Klíčová, L.; Šebej, P.; Štacko, P.; Filippov, Sergey K.; Bogomolova, Anna; Padilla, M.; Klán, P.

    2012-01-01

    Roč. 28, č. 43 (2012), s. 15185-15192 ISSN 0743-7463 R&D Projects: GA ČR GAP108/12/0640 Institutional support: RVO:61389013 Keywords : CTAB * reverse micelles * AFM Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.187, year: 2012

  19. Micelle System Based on Molecular Economy Principle for Overcoming Multidrug Resistance and Inhibiting Metastasis.

    Science.gov (United States)

    Qi, Yan; Qin, Xianya; Yang, Conglian; Wu, Tingting; Qiao, Qi; Song, Qingle; Zhang, Zhiping

    2018-03-05

    The high mortality of cancer is mainly attributed to multidrug resistance (MDR) and metastasis. A simple micelle system was constructed here to codeliver doxorubicin (DOX), adjudin (ADD), and nitric oxide (NO) for overcoming MDR and inhibiting metastasis. It was devised based on the "molecular economy" principle as the micelle system was easy to fabricate and exhibited high drug loading efficiency, and importantly, each component of the micelles would exert one or more active functions. DOX acted as the main cell killing agent supplemented with ADD, NO, and d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS). MDR was overcome by synergistic effects of mitochondria inhibition agents, TPGS and ADD. A TPGS-based NO donor can be used as a drug carrier, and it can release NO to enhance drug accumulation and penetration in tumor, resulting in a positive cycle of drug delivery. This DOX-ADD conjugate self-assembly system demonstrated controlled drug release, increased cellular uptake and cytotoxicity, enhanced accumulation at tumor site, and improved in vivo metastasis inhibition of breast cancer. The micelles can fully take advantage of the functions of each component, and they provide a potential strategy for nanomedicine design and clinical cancer treatment.

  20. Local chemistry of the surfactant's head groups determines protein stability in reverse micelles.

    Science.gov (United States)

    Senske, Michael; Xu, Yao; Bäumer, Alexander; Schäfer, Sarah; Wirtz, Hanna; Savolainen, Janne; Weingärtner, Hermann; Havenith, Martina

    2018-03-28

    When comparing protein folding in vitro and in vivo significant differences have been found. This has been attributed to crowding and confinement effects. Using a combination of GHz- and THz-dielectric relaxation spectroscopy and MD simulations, we studied hydration dynamics and reviewed protein stability data inside sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and cetyltrimethylammonium bromide (CTAB) reverse micelles which are model systems for confinement. We find that water inside anionic AOT and cationic CTAB reverse micelles is characterized by a strong dielectric depolarization giving rise to a very low relative permittivity compared to an unconfined solution. Despite differences in the hydration dynamics of the surfactant's head groups, simulations using the two-phase thermodynamics method predict a similar reduction in water entropy for both reverse micelle systems compared to bulk water. When we compare the stability data of proteins in these reverse micelles we find that in contrast to our initial expectation, protein stability correlates rather with the local chemistry of the hydrated head groups than with the excluded volume effect or the low global permittivity.

  1. Intrinsically active nanobody-modified polymeric micelles for tumor-targeted combination therapy

    Czech Academy of Sciences Publication Activity Database

    Talelli, M.; Oliveira, S.; Rijcken, C. J. F.; Pieters, E. H. E.; Etrych, Tomáš; Ulbrich, Karel; van Nostrum, R. C. F.; Storm, G.; Hennink, W. E.; Lammers, T.

    2013-01-01

    Roč. 34, č. 4 (2013), s. 1255-1260 ISSN 0142-9612 R&D Projects: GA AV ČR IAA400500806; GA ČR GAP301/11/0325 Institutional research plan: CEZ:AV0Z40500505 Keywords : polymeric micelle * doxorubicin * active targeting Subject RIV: CD - Macromolecular Chemistry Impact factor: 8.312, year: 2013

  2. Core-cross-linked polymeric micelles: a versatile nanomedicine platform with broad applicability

    NARCIS (Netherlands)

    Hu, Q.

    2015-01-01

    This dissertation addresses the broad applicability of the nanomedicine platform core-cross-linked polymeric micelles (CCL-PMs) composed of thermosensitive mPEG-b-pHPMAmLacn block copolymers. In Chapter 1, a general introduction to nanomedicines is provided, with a particular focus on polymeric

  3. Tailoring the physicochemical properties of core-crosslinked polymeric micelles for pharmaceutical applications

    Czech Academy of Sciences Publication Activity Database

    Hu, Q.; Rijcken, C. J. F.; van Gaal, E.; Brundel, P.; Kostková, Hana; Etrych, Tomáš; Weber, B.; Barz, M.; Kiessling, F.; Prakash, J.; Storm, G.; Hennink, W. E.; Lammers, T.

    2016-01-01

    Roč. 244, Part B (2016), s. 314-325 ISSN 0168-3659. [European Symposium on Controlled Drug Delivery /14./. Egmond aan Zee, 13.04.2016-15.04.2016] Institutional support: RVO:61389013 Keywords : nanomedicine * drug targeting * polymeric micelles Subject RIV: CD - Macromolecular Chemistry Impact factor: 7.786, year: 2016

  4. Core-crosslinked polymeric micelles with controlled release of covalently entrapped doxorubicin

    Czech Academy of Sciences Publication Activity Database

    Talelli, M.; Iman, M.; Varkouhi, A. K.; Rijcken, C. J. F.; Schiffelers, R. M.; Etrych, Tomáš; Ulbrich, Karel; van Nostrum, C. F.; Lammers, T.; Storm, G.; Hennink, W. E.

    2010-01-01

    Roč. 31, č. 30 (2010), s. 7797-7804 ISSN 0142-9612 R&D Projects: GA AV ČR KAN200200651; GA AV ČR IAA400500806 Institutional research plan: CEZ:AV0Z40500505 Keywords : doxorubicin * cancer therapy * polymeric micelle Subject RIV: CD - Macromolecular Chemistry Impact factor: 7.883, year: 2010

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  6. Polymeric Micelle-Mediated Delivery of DNA-Targeting Organometallic Complexes for Resistant Ovarian Cancer Treatment.

    Science.gov (United States)

    Duan, Xiaopin; Liu, Demin; Chan, Christina; Lin, Wenbin

    2015-08-26

    Three half-sandwich iridium and ruthenium organometallic complexes with high cytotoxicity are synthesized, and their anticancer mechanisms are elucidated. The organometallic complexes can interact with DNA through coordination or intercalation, thereby inducing apoptosis and inhibiting proliferation of resistant cancer cells. The organometallic complexes are then incorporated into polymeric micelles through the polymer-metal coordination between poly(ethylene glycol)-b-poly(glutamic acid) [PEG-b-P(Glu)] and organometallic complexes to further enhance their anticancer effects as a result of the enhanced permeability and retention effect. The micelles with particle sizes of ≈60 nm are more efficiently internalized by cancer cells than the corresponding complexes, and selectively dissociate and release organometallic anticancer agents within late endosomes and lysosomes, thereby enhancing drug delivery to the nuclei of cancer cells and facilitating their interactions with DNA. Thus, the micelles display higher antitumor activity than the organometallic complexes alone with a lack of the systemic toxicity in a mouse xenograft model of cisplatin-resistant human ovarian cancer. These results suggest that the polymeric micelles carrying anticancer organometallic complexes provide a promising platform for the treatment of resistant ovarian cancer and other hard-to-treat solid tumors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

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

    2017-06-01

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

  8. 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.

  9. Sub-20 nm Stable Micelles Based on a Mixture of Coiled-Coils: A Platform for Controlled Ligand Presentation.

    Science.gov (United States)

    Ang, JooChuan; Ma, Dan; Jung, Benson T; Keten, Sinan; Xu, Ting

    2017-11-13

    Ligand-functionalized, multivalent nanoparticles have been extensively studied for biomedical applications from imaging agents to drug delivery vehicles. However, the ligand cluster size is usually heterogeneous and the local valency is ill-defined. Here, we present a mixed micelle platform hierarchically self-assembled from a mixture of two amphiphilic 3-helix and 4-helix peptide-polyethylene glycol (PEG)-lipid hybrid conjugates. We demonstrate that the local multivalent ligand cluster size on the micelle surface can be controlled based on the coiled-coil oligomeric state. The oligomeric states of mixed peptide bundles were found to be in their individual native states. Similarly, mixed micelles indicate the orthogonal self-association of coiled-coil amphiphiles. Using differential scanning calorimetry, fluorescence recovery spectroscopy, and coarse-grained molecular dynamics simulation, we studied the distribution of coiled-coil bundles within the mixed micelles and observed migration of coiled-coils into nanodomains within the sub-20 nm mixed micelle. This report provides important insights into the assembly and formation of nanophase-separated micelles with precise control over the local multivalent state of ligands on the micelle surface.

  10. Conjugation of Lectin to Poly(ε-caprolactone-block-glycopolymer Micelles for In Vitro Intravesical Drug Delivery

    Directory of Open Access Journals (Sweden)

    Ning Ning Li

    2016-10-01

    Full Text Available Amphiphilic poly(ε-caprolactone-block-poly[2-(α-d-mannopyranosyloxy ethyl acrylamide] (PCL-b-PManEA block copolymers were synthesized via a combination of ring-opening polymerization (ROP, reversible addition-fragmentation chain transfer (RAFT polymerization and reactive ester-amine reaction. The PCL-b-PManEA block copolymers can self-assemble into micelles and encapsulate anticancer drug doxorubicin (DOX. To enhance mucoadhesive property of the resulting DOX-loaded PCL-b-PManEA micelles, Concanavalin A (ConA lectin was further conjugated with the micelles. Turbidimetric assay using mucin shows that the DOX-loaded PCL-b-PManEA@ConA micelles are mucoadhesive. DOX release from the DOX-loaded PCL-b-PManEA@ConA micelles in artificial urine at 37 °C exhibits an initial burst release, followed by a sustained and slow release over three days. Confocal laser scanning microscope (CLSM images indicate that the DOX-loaded PCL-b-PManEA@ConA micelles can be effectively internalized by UMUC3 human urothelial carcinoma cells. The DOX-loaded PCL-b-PManEA@ConA micelles exhibit significant cytotoxicity to these cells.

  11. Bioreducible Micelles Self-Assembled from Poly(ethylene glycol-Cholesteryl Conjugate As a Drug Delivery Platform

    Directory of Open Access Journals (Sweden)

    Chulsu Baek

    2015-11-01

    Full Text Available The ability of polymeric micelles to self-assemble into nanosized particles has created interest in their application as potential anticancer drug delivery systems. A poly(ethylene glycol-cholesteryl conjugate (Chol-ss-PEG-ss-Chol connected by cleavable disulfide linkages was synthesized and used as a nanocarrier for in vitro release of doxorubicin (DOX. Owing to its amphiphilic structure, Chol-ss-PEG-ss-Chol was able to self-assemble into micelles with an average diameter 18.6 nm in aqueous solution. The micelles formed large aggregates due to the shedding of the PEG shell through cleavage of disulfide bonds in a reductive environment. The in vitro release studies revealed that Chol-ss-PEG-ss-Chol micelles released 80% and approximately 9% of the encapsulated DOX within 6 h under reductive and non-reductive conditions, respectively. The glutathione (GSH-mediated intracellular drug delivery was investigated in a KB cell line. The cytotoxicity of DOX-loaded micelles indicated a higher cellular anti-proliferative effect against GSH-pretreated than untreated KB cells. Furthermore, confocal laser scanning microscopy (CLSM measurement demonstrated that Chol-ss-PEG-ss-Chol micelles exhibited faster drug release in GSH-pretreated KB cells than untreated KB cells. These results suggest the potential usefulness of disulfide-based polymeric micelles as controlled drug delivery carriers.

  12. Effects of temperature on the rheological behavior of worm-like micelles in a mixed nonionic surfactant system.

    Science.gov (United States)

    Hashizaki, Kaname; Taguchi, Hiroyuki; Saito, Yoshihiro

    2009-01-01

    We examined the effects of temperature on the rheological behavior of worm-like micelles in a nonionic surfactant system consisting of polyoxyethylene (10) phytosterol (PhyEO(10))/glyceryl monocaprylate (GFA-C(8))/Water. First, the phase diagram of a PhyEO(10)/GFA-C(8)/Water system was examined when the weight ratio, R, of GFA-C(8) to the total surfactants was changed keeping the total concentration of the surfactants at 5 wt%. The formation of worm-like micelles was confirmed over a wide temperature range. Next, the effect of temperature on the rheological properties of the worm-like micelles was examined. From steady-flow viscosity measurements of the worm-like micelles, it was found that the zero-shear viscosity (eta(0)) gave a maximum value more than 1,000 times greater than the minimum value in the temperature range 20-50 degrees C. Further, the temperature at which the maximum eta(0) was observed decreased with increasing R value. These results indicate that there is an optimal temperature at which the entanglement of worm-like micelles is at its greatest. From dynamic viscoelasticity measurements, it was shown that the viscoelastic behavior observed for the worm-like micelles was consistent with the Maxwell model, which is the basic model for a viscoelastic body. In addition, the plateau modulus (G(0)), which reflects the volume fraction of entangled worm-like micelles, gradually increased with increasing temperature, while the relaxation time (tau), which reflects the disentanglement time of the worm-like micelles, rapidly decreased with increasing temperature. From these results, it was clarified that, for a nonionic worm-like micelle, tau influences the change in eta(0) more strongly than G(0).

  13. Spectroscopic investigation of the aggregation state of amphotericin B during loading, freeze-drying, and reconstitution of polymeric micelles.

    Science.gov (United States)

    Adams, Monica; Kwon, Glen S

    2004-11-22

    To investigate the relative aggregation state of amphotericin B (AmB) during loading and reconstitution of polymeric micelles. Hexanoate and stearate derivatives of PEO-b-p (L-Asp) were prepared. The polymers and AmB were dissolved in methanol (MeOH). Milli-Q water was then added slowly, and the MeOH was removed via rotary evaporation. The solutions were freeze-dried in the presence of trehalose. During micelle preparation, the aggregation state of AmB was assessed using absorption spectroscopy. Upon reconstitution, the samples were analyzed using vapor-pressure osmometry, size-exclusion chromatography (SEC), and absorption spectroscopy. The absorption spectrum of AmB in the presence of the block copolymers was compared to that of AmB alone under the same conditions. AmB was loaded into micelles prepared from acyl derivatives of PEO-b-p (L-Asp). Absorption spectroscopy indicated that the aggregation state was preserved during the loading process. AmB exists in a self-aggregated state in polymeric micelles containing hexanoate ester cores and in a relatively monomeric state in polymeric micelles containing stearate ester cores. Vapor-pressure osmometry confirmed the isotonicity of the formulations, while SEC indicated that the micelles were approximately 10(6) g/mol. Depending on the polymer structure and assembly conditions, it is possible to encapsulate AmB in a relatively nonaggregated or aggregated state in micelles prepared from acyl derivatives of PEO-b-p (L-Asp). In polymeric micelles containing stearate side chains, AmB was loaded in a nearly monomeric state, possibly due to interaction with the stearate side chains. The final aggregation state of the drug is preserved during lyophilization and reconstitution of polymeric micelles prepared by a novel solvent evaporation procedure.

  14. The effect of block copolymer structure on the internalization of polymeric micelles by human breast cancer cells.

    Science.gov (United States)

    Mahmud, Abdullah; Lavasanifar, Afsaneh

    2005-10-10

    The objective of this study was to assess the effect of hydrophilic/hydrophobic block chain lengths on the internalization of poly(ethylene oxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL) micelles by cancer cells. PEO-b-PCL block copolymers with varied PEO and PCL chain lengths were synthesized, assembled to polymeric micelles and loaded with a hydrophobic fluorescent probe (DiI) through a co-solvent evaporation method of physical encapsulation. The slow release of the fluorescent probe from the micellar structure was evidenced following DiI transfer to lipid vesicles. The extent of micellar uptake by cancer cells was investigated through their incubation with MCF-7 cells followed by measurement of the fluorescent emission intensity of DiI (lambda=550 nm) in separated lysed cells. Cellular internalization of polymeric micelles was confirmed by laser scanning microscopy. The mechanism of micellar uptake was investigated by pretreatment of MCF-7 cells with chlorpromazine and cytochalasin B. Encapsulation of DiI in PEO-b-PCL micelles lowered the extent and rate of hydrophobic probe internalization by cancer cells. For polymeric micelles with 5000 gmol(-1) of PCL and varied PEO molecular weights of 2000, 5000 and 13,000 gmol(-1), maximum uptake was observed at a PEO molecular weight of 5000 gmol(-1). For polymeric micelles with 5000 gmol(-1) of PEO and varied PCL molecular weights of 5000, 13,000 and 24,000 gmol(-1), maximum uptake was observed at 13,000 gmol(-1) of PCL. Chlorpromazine reduced the cellular uptake of PEO-b-PCL micelles independent from the block copolymer structure, pointing to the involvement of clathrin mediated endocytosis mechanisms in the uptake of polymeric micelles by cancer cells. Inhibition of cellular uptake of PEO-b-PCL micelles by cytochalasin B, on the other hand, was found to be dependent on the chemical structure of the core/shell forming blocks.

  15. Anticancer effect and mechanism of polymer micelle-encapsulated quercetin on ovarian cancer

    Science.gov (United States)

    Gao, Xiang; Wang, Bilan; Wei, Xiawei; Men, Ke; Zheng, Fengjin; Zhou, Yingfeng; Zheng, Yu; Gou, Maling; Huang, Meijuan; Guo, Gang; Huang, Ning; Qian, Zhiyong; Wei, Yuquan

    2012-10-01

    Encapsulation of hydrophobic agents in polymer micelles can improve the water solubility of cargos, contributing to develop novel drugs. Quercetin (QU) is a hydrophobic agent with potential anticancer activity. In this work, we encapsulated QU into biodegradable monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelles and tried to provide proof-of-principle for treating ovarian cancer with this nano-formulation of quercetin. These QU loaded MPEG-PCL (QU/MPEG-PCL) micelles with drug loading of 6.9% had a mean particle size of 36 nm, rendering the complete dispersion of quercetin in water. QU inhibited the growth of A2780S ovarian cancer cells on a dose dependent manner in vitro. Intravenous administration of QU/MPEG-PCL micelles significantly suppressed the growth of established xenograft A2780S ovarian tumors through causing cancer cell apoptosis and inhibiting angiogenesis in vivo. Furthermore, the anticancer activity of quercetin on ovarian cancer cells was studied in vitro. Quercetin treatment induced the apoptosis of A2780S cells associated with activating caspase-3 and caspase-9. MCL-1 downregulation, Bcl-2 downregulation, Bax upregulation and mitochondrial transmembrane potential change were observed, suggesting that quercetin may induce apoptosis of A2780S cells through the mitochondrial apoptotic pathway. Otherwise, quercetin treatment decreased phosphorylated p44/42 mitogen-activated protein kinase and phosphorylated Akt, contributing to inhibition of A2780S cell proliferation. Our data suggested that QU/MPEG-PCL micelles were a novel nano-formulation of quercetin with a potential clinical application in ovarian cancer therapy.

  16. PSMA ligand conjugated PCL-PEG polymeric micelles targeted to prostate cancer cells.

    Directory of Open Access Journals (Sweden)

    Jian Jin

    Full Text Available In this content, a small molecular ligand of prostate specific membrane antigen (SMLP conjugated poly (caprolactone (PCL-b-poly (ethylene glycol (PEG copolymers with different block lengths were synthesized to construct a satisfactory drug delivery system. Four different docetaxel-loaded polymeric micelles (DTX-PMs were prepared by dialysis with particle sizes less than 60 nm as characterized by dynamic light scattering (DLS and transmission electron microscope (TEM. Optimization of the prepared micelles was conducted based on short-term stability and drug-loading content. The results showed that optimized systems were able to remain stable over 7 days. Compared with Taxotere, DTX-PMs with the same ratio of hydrophilic/hydrophobic chain length displayed similar sustained release behaviors. The cytotoxicity of the optimized targeted DTX-PCL12K-PEG5K-SMLP micelles (DTX-PMs2 and non-targeted DTX-PCL12K-mPEG5K micelles (DTX-PMs1 were evaluated by MTT assays using prostate specific membrane antigen (PSMA positive prostate adenocarcinoma cells (LNCaP. The results showed that the targeted micelles had a much lower IC50 than their non-targeted counterparts (48 h: 0.87 ± 0.27 vs 13.48 ± 1.03 µg/ml; 72 h: 0.02 ± 0.008 vs 1.35 ± 0.54 µg/ml. In vitro cellular uptake of PMs2 showed 5-fold higher fluorescence intensity than that of PMs1 after 4 h incubation. According to these results, the novel nano-sized drug delivery system based on DTX-PCL-PEG-SMLP offers great promise for the treatment of prostatic cancer.

  17. Sodium deoxycholate mediated enhanced solubilization and stability of hydrophobic drug Clozapine in pluronic micelles

    Science.gov (United States)

    Singla, Pankaj; Singh, Onkar; Chabba, Shruti; Aswal, V. K.; Mahajan, Rakesh Kumar

    2018-02-01

    In this report, the solubilization behaviour of a hydrophobic drug Clozapine (CLZ) in micellar suspensions of pluronics having different hydrophilic lipophilic balance (HLB) ratios viz. P84, F127 and F108 in the absence and presence of bile salt sodium deoxycholate (SDC) has been studied. UV-Vis spectroscopy has been exploited to determine the solubilization capacity of the investigated micellar systems in terms of drug loading efficiency, average number of drug molecules solubilized per micelle (ns), partition coefficient (P) and standard free energy of solubilization (Δ G°). The morphological and structural changes taking place in pluronics in different concentration regimes of SDC and with the addition of drug CLZ has been explored using dynamic light scattering (DLS) and small angle neutron scattering (SANS) measurements. The SANS results revealed that aggregation behaviour of pluronic-SDC mixed micelles gets improved in the presence of drug. The micropolarity measurements have been performed to shed light on the locus of solubilization of the drug in pure and mixed micellar systems. The compatibility between CLZ and drug carriers (pluronics and SDC) was confirmed using powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Among the investigated systems, P84-SDC mixed system was found to be highly efficient for CLZ loading. The long term stability data indicated that CLZ loaded P84-SDC mixed micellar formulation remained stable for 3 months at room temperature. Further, it was revealed that the CLZ loaded P84-SDC mixed micelles are converted into CLZ loaded pure P84 micelles at 30-fold dilutions which remain stable up to 48-fold dilutions. The results from the present studies suggest that P84-SDC mixed micelles can serve as suitable delivery vehicles for hydrophobic drug CLZ.

  18. Radiochromic leuco dye micelle hydrogels: II. Low diffusion rate leuco crystal violet gel

    Energy Technology Data Exchange (ETDEWEB)

    Babic, Steven; Battista, Jerry; Jordan, Kevin [Department of Physics and Engineering, London Regional Cancer Program at London Health Sciences Centre, 790 Commissioners Road East, London, Ontario, N6A 4L6 (Canada)

    2009-11-21

    Radiation-sensitive hydrogels offer the capability of verifying intricate dose distributions in three-dimensional (3D) space conveniently in a single measurement with sub-millimetre spatial resolution. In this study, a new radiochromic hydrogel called leuco crystal violet (LCV) micelle gel is introduced. Upon irradiation, LCV converts to crystal violet (CV{sup +}). Triton X-100 micelles are used to provide the required hybrid-interfacing environment to dissolve LCV. The diffusion coefficient of the LCV gel has been measured to be 0.036 {+-} 0.001 mm{sup 2} h{sup -1}, which is a factor of 25 times less than the standard radiochromic ferrous xylenol-orange (FX) gel; LCV gels without Triton X-100 micelles have a diffusion coefficient of 0.33 {+-} 0.02 mm{sup 2} h{sup -1}. The LCV gel formulation contains: 1 mM LCV, 25 mM trichloroacetic acid, 4 mM Triton X-100 and 4% w/w gelatin. The primary innovative feature of this 3D hydrogel is that the radiation-induced CV{sup +} dye is more soluble in the Triton X-100 micelles than in the surrounding water which consequently leads to more stable post-irradiation dose distributions. A dosimetric characterization revealed that the dose response is reproducible to within 1% over three separate batches, independent of energy, dose rate and dose fractionation but is affected by the temperature ({approx}4% per deg. C) during irradiation. LCV micelle gels scanned optically with a yellow light source are a promising system for 3D dose verification. They may prove to be, especially, useful for scanning large volume dosimeters (i.e. 20 cm) since they are easily manufactured, transparent and near colourless prior to irradiation.

  19. Radiochromic leuco dye micelle hydrogels: II. Low diffusion rate leuco crystal violet gel

    Science.gov (United States)

    Babic, Steven; Battista, Jerry; Jordan, Kevin

    2009-11-01

    Radiation-sensitive hydrogels offer the capability of verifying intricate dose distributions in three-dimensional (3D) space conveniently in a single measurement with sub-millimetre spatial resolution. In this study, a new radiochromic hydrogel called leuco crystal violet (LCV) micelle gel is introduced. Upon irradiation, LCV converts to crystal violet (CV+). Triton X-100 micelles are used to provide the required hybrid-interfacing environment to dissolve LCV. The diffusion coefficient of the LCV gel has been measured to be 0.036 ± 0.001 mm2 h-1, which is a factor of 25 times less than the standard radiochromic ferrous xylenol-orange (FX) gel; LCV gels without Triton X-100 micelles have a diffusion coefficient of 0.33 ± 0.02 mm2 h-1. The LCV gel formulation contains: 1 mM LCV, 25 mM trichloroacetic acid, 4 mM Triton X-100 and 4% w/w gelatin. The primary innovative feature of this 3D hydrogel is that the radiation-induced CV+ dye is more soluble in the Triton X-100 micelles than in the surrounding water which consequently leads to more stable post-irradiation dose distributions. A dosimetric characterization revealed that the dose response is reproducible to within 1% over three separate batches, independent of energy, dose rate and dose fractionation but is affected by the temperature (~4% per °C) during irradiation. LCV micelle gels scanned optically with a yellow light source are a promising system for 3D dose verification. They may prove to be, especially, useful for scanning large volume dosimeters (i.e. 20 cm) since they are easily manufactured, transparent and near colourless prior to irradiation.

  20. Detecting frogs as prey in the diets of introduced mammals: a comparison between morphological and DNA-based diet analyses.

    Science.gov (United States)

    Egeter, Bastian; Bishop, Phillip J; Robertson, Bruce C

    2015-03-01

    Amphibians are currently the most threatened group of vertebrates worldwide, and introduced fauna play a major role in their decline. The control of introduced predators to protect endangered species is often based on predation rates derived from diet studies of predators, but prey detection probabilities using different techniques are variable. We measured the detectability of frogs as prey, using morphological and DNA-based diet analyses, in the stomachs and faeces of four mammal species that have been introduced to many areas of the world. Frogs (Litoria raniformis) were fed to rats (Rattus norvegicus and R. rattus), mice (Mus musculus) and hedgehogs (Erinaceus europaeus). DNA-based analysis outperformed morphological analysis, increasing the prey detection rate from 2% to 70% in stomachs and from 0% to 53% in faeces. In most cases, utilizing either stomachs or faeces did not affect the success of prey DNA detection; however, using faeces extended the detectability half-life from 7 to 21 h. This study is the first to measure prey DNA detection periods in mammalian stomachs, and the first to compare prey DNA detection periods in the stomachs and faeces of vertebrates. The results indicate that DNA-based diet analysis provides a more reliable approach for detecting amphibians as prey and has the potential to be used to estimate the rate of predation by introduced mammals on endangered amphibians. © 2014 John Wiley & Sons Ltd.

  1. A molecular dynamics study of local pressures and interfacial tensions of SDS micelles and dodecane droplets in water.

    Science.gov (United States)

    Kitabata, Masahiro; Fujimoto, Kazushi; Yoshii, Noriyuki; Okazaki, Susumu

    2016-06-14

    To obtain the radial (normal) and lateral (transverse) components of the local pressure tensor, PN(R) and PT(R), respectively, and the interfacial tension of micelles, molecular dynamics (MD) calculations were performed for spherical sodium dodecyl sulfate (SDS) micelles. The local pressure tensor was calculated as a function of radial distance R using the Irving-Kirkwood formula. Similar MD calculations were also carried out for an n-dodecane droplet in water to compare the differences in the local pressure and interfacial tension values with those of the micelles. The calculated interfacial tensions were 20 ± 5 and 44 ± 10 mN/m for the SDS micelles and dodecane droplets, respectively. The excess free energies due to the interfacial tension were 340 and 1331 kJ/mol for the SDS micelle and dodecane droplet, respectively. The micelles are stabilized by 991 kJ/mol by covering their hydrophobic cores with hydrophilic groups. The dodecane droplet has a large interfacial tension caused by the zero or positive values of PN(R) - PT(R) at all values of R. In contrast, the small interfacial tension in the SDS micelles comes from the negative PN(R) - PT(R) values over a wide range of R. The pressure difference between the inside and outside of the oil droplet and its interfacial tension well satisfies the Laplace equation. However, the hydrophobic core of the SDS micelle is quite different from the liquid alkane, and the SDS micelles do not follow Laplace's picture. Decomposing the interfacial tension into contributions from various interactions, it is found that those between charged and polar groups dominate the interfacial tension of the SDS micelles. The positive electrostatic potential (1.3 V) on the micelle surface and the negative potential (-0.15 V) on the oil droplet contribute to the interfacial tensions by 19 and 0.5 mN/m, respectively. Thus, the interfacial tension of the SDS micelles is produced by electrostatic interactions, in contrast to the dodecane

  2. Evaluating the statistical power of DNA-based identification, exemplified by 'The missing grandchildren of Argentina'.

    Science.gov (United States)

    Kling, Daniel; Egeland, Thore; Piñero, Mariana Herrera; Vigeland, Magnus Dehli

    2017-11-01

    Methods and implementations of DNA-based identification are well established in several forensic contexts. However, assessing the statistical power of these methods has been largely overlooked, except in the simplest cases. In this paper we outline general methods for such power evaluation, and apply them to a large set of family reunification cases, where the objective is to decide whether a person of interest (POI) is identical to the missing person (MP) in a family, based on the DNA profile of the POI and available family members. As such, this application closely resembles database searching and disaster victim identification (DVI). If parents or children of the MP are available, they will typically provide sufficient statistical evidence to settle the case. However, if one must resort to more distant relatives, it is not a priori obvious that a reliable conclusion is likely to be reached. In these cases power evaluation can be highly valuable, for instance in the recruitment of additional family members. To assess the power in an identification case, we advocate the combined use of two statistics: the Probability of Exclusion, and the Probability of Exceedance. The former is the probability that the genotypes of a random, unrelated person are incompatible with the available family data. If this is close to 1, it is likely that a conclusion will be achieved regarding general relatedness, but not necessarily the specific relationship. To evaluate the ability to recognize a true match, we use simulations to estimate exceedance probabilities, i.e. the probability that the likelihood ratio will exceed a given threshold, assuming that the POI is indeed the MP. All simulations are done conditionally on available family data. Such conditional simulations have a long history in medical linkage analysis, but to our knowledge this is the first systematic forensic genetics application. Also, for forensic markers mutations cannot be ignored and therefore current models and

  3. Quantification of Plasmodiophora brassicae Using a DNA-Based Soil Test Facilitates Sustainable Oilseed Rape Production.

    Science.gov (United States)

    Wallenhammar, Ann-Charlotte; Gunnarson, Albin; Hansson, Fredrik; Jonsson, Anders

    2016-04-22

    Outbreaks of clubroot disease caused by the soil-borne obligate parasite Plasmodiophora brassicae are common in oilseed rape (OSR) in Sweden. A DNA-based soil testing service that identifies fields where P. brassicae poses a significant risk of clubroot infection is now commercially available. It was applied here in field surveys to monitor the prevalence of P. brassicae DNA in field soils intended for winter OSR production and winter OSR field experiments. In 2013 in Scania, prior to planting, P. brassicae DNA was detected in 60% of 45 fields on 10 of 18 farms. In 2014, P. brassicae DNA was detected in 44% of 59 fields in 14 of 36 farms, in the main winter OSR producing region in southern Sweden. P. brassicae was present indicative of a risk for >10% yield loss with susceptible cultivars (>1300 DNA copies g soil(-1)) in 47% and 44% of fields in 2013 and 2014 respectively. Furthermore, P. brassicae DNA was indicative of sites at risk of complete crop failure if susceptible cultivars were grown (>50 000 copies g(-1) soil) in 14% and 8% of fields in 2013 and 2014, respectively. A survey of all fields at Lanna research station in western Sweden showed that P. brassicae was spread throughout the farm, as only three of the fields (20%) showed infection levels below the detection limit for P.brassicae DNA, while the level was >50,000 DNA copies g(-1) soil in 20% of the fields. Soil-borne spread is of critical importance and soil scraped off footwear showed levels of up to 682 million spores g(-1) soil. Soil testing is an important tool for determining the presence of P. brassicae and providing an indication of potential yield loss, e.g., in advisory work on planning for a sustainable OSR crop rotation. This soil test is gaining acceptance as a tool that increases the likelihood of success in precision agriculture and in applied research conducted in commercial oilseed fields and at research stations. The present application highlights the importance of prevention of

  4. Quantification of Plasmodiophora brassicae Using a DNA-Based Soil Test Facilitates Sustainable Oilseed Rape Production

    Directory of Open Access Journals (Sweden)

    Ann-Charlotte Wallenhammar

    2016-04-01

    Full Text Available Outbreaks of clubroot disease caused by the soil-borne obligate parasite Plasmodiophora brassicae are common in oilseed rape (OSR in Sweden. A DNA-based soil testing service that identifies fields where P. brassicae poses a significant risk of clubroot infection is now commercially available. It was applied here in field surveys to monitor the prevalence of P. brassicae DNA in field soils intended for winter OSR production and winter OSR field experiments. In 2013 in Scania, prior to planting, P. brassicae DNA was detected in 60% of 45 fields on 10 of 18 farms. In 2014, P. brassicae DNA was detected in 44% of 59 fields in 14 of 36 farms, in the main winter OSR producing region in southern Sweden. P. brassicae was present indicative of a risk for >10% yield loss with susceptible cultivars (>1300 DNA copies g soil−1 in 47% and 44% of fields in 2013 and 2014 respectively. Furthermore, P. brassicae DNA was indicative of sites at risk of complete crop failure if susceptible cultivars were grown (>50 000 copies g−1 soil in 14% and 8% of fields in 2013 and 2014, respectively. A survey of all fields at Lanna research station in western Sweden showed that P. brassicae was spread throughout the farm, as only three of the fields (20% showed infection levels below the detection limit for P.brassicae DNA, while the level was >50,000 DNA copies g−1 soil in 20% of the fields. Soil-borne spread is of critical importance and soil scraped off footwear showed levels of up to 682 million spores g−1 soil. Soil testing is an important tool for determining the presence of P. brassicae and providing an indication of potential yield loss, e.g., in advisory work on planning for a sustainable OSR crop rotation. This soil test is gaining acceptance as a tool that increases the likelihood of success in precision agriculture and in applied research conducted in commercial oilseed fields and at research stations. The present application highlights the importance of

  5. Quantitative correlation between counterion (X binding affinity to cationic micelles and X – Induced micellar growth for substituted iodobenzoates (X

    Directory of Open Access Journals (Sweden)

    Nor Saadah M. Yusof

    2017-05-01

    Full Text Available A new semi-empirical kinetic (SEK method has been used to calculate the values of KXBr or RXBr (X represents substituted iodobenzoates, with KX and KBr representing CTABr micellar binding constants of counterions X− (in the presence of either spherical or non-spherical micelles and Br− (in the presence of only spherical micelles, respectively. Steady-shear rheological properties of mixed 0.015 M CTABr/[MX] aqueous solutions reveal the presence of flexible wormlike micelles where MX represents sodium 3- and 4-iodobenzoates. The maxima of the plots of viscosity vs. [MX] at 0.015 M CTABr for MX representing sodium 3- and 4-iodobenzoates support the presence of long linear and entangled wormlike micelles.

  6. Structure of polymer micelles close to the solid interface. A grazing incidence small angle neutron scattering study.

    Science.gov (United States)

    Wolff, M; Magerl, A; Zabel, H

    2005-02-01

    Block copolymers are widely used in industry. For scientific interests their aqueous solutions offer a model system for the investigation of crystallisation as the macromolecules agglomerate for elevated concentrations into micelles, which crystallise when a critical volume fraction is reached. We report on grazing incidence small angle neutron scattering (GISANS) or near surface small angle neutron scattering (NS-SANS) as an experimental tool to investigate the micelle crystallisation close to interfaces with different chemical termination. We find that in general crystallization is suppressed at a repulsive surface and favoured at an attractive one. Furthermore we show that the crystallization close the interface can be controlled by the micelle stability, resulting from the different composition and length of the monomers. The effect of the interface is found more important for a high micelle stability, whereas for a low stability it is shadowed by adsorbed monomers.

  7. Fabrication and characterization of nuclear localization signal-conjugated glycol chitosan micelles for improving the nuclear delivery of doxorubicin

    Directory of Open Access Journals (Sweden)

    Zhao J

    2012-09-01

    Full Text Available Jingmou Yu,1 Xin Xie,1 Meirong Zheng,1 Ling Yu,2 Lei Zhang,1 Jianguo Zhao,1 Dengzhao Jiang,1 Xiangxin Che11Key Laboratory of Systems Biology Medicine of Jiangxi Province, College of Basic Medical Science, Jiujiang University, Jiujiang, 2Division of Nursing, 2nd Affiliated Hospital, Yichun University, Yichun, People's Republic of ChinaBackground: Supramolecular micelles as drug-delivery vehicles are generally unable to enter the nucleus of nondividing cells. In the work reported here, nuclear localization signal (NLS-modified polymeric micelles were studied with the aim of improving nuclear drug delivery.Methods: In this research, cholesterol-modified glycol chitosan (CHGC was synthesized. NLS-conjugated CHGC (NCHGC was synthesized and characterized using proton nuclear magnetic resonance spectroscopy, dynamic light scattering, and fluorescence spectroscopy. Doxorubicin (DOX, an anticancer drug with an intracellular site of action in the nucleus, was chosen as a model drug. DOX-loaded micelles were prepared by an emulsion/solvent evaporation method. The cellular uptake of different DOX formulations was analyzed by flow cytometry and confocal laser scanning microscopy. The cytotoxicity of blank micelles, free DOX, and DOX-loaded micelles in vitro was investigated by 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay in HeLa and HepG2 cells.Results: The degree of substitution was 5.9 cholesterol and 3.8 NLS groups per 100 sugar residues of the NCHGC conjugate. The critical aggregation concentration of the NCHGC micelles in aqueous solution was 0.0209 mg/mL. The DOX-loaded NCHGC (DNCHGC micelles were observed as being almost spherical in shape under transmission electron microscopy, and the size was determined as 248 nm by dynamic light scattering. The DOX-loading content of the DNCHGC micelles was 10.1%. The DOX-loaded micelles showed slow drug-release behavior within 72 hours in vitro. The DNCHGC micelles exhibited greater

  8. Solubilized delivery of paliperidone palmitate by D-alpha-tocopheryl polyethylene glycol 1000 succinate micelles for improved short-term psychotic management.

    Science.gov (United States)

    Muthu, Madaswamy S; Sahu, Ashish K; Sonali; Abdulla, Allabakshi; Kaklotar, Dhansukh; Rajesh, Chellappa V; Singh, Sanjay; Pandey, Bajarangprasad L

    2016-01-01

    The objective of this work was to formulate paliperidone palmitate-loaded d-alpha-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS or TPGS) micelles for improved antipsychotic effect during short-term management of psychotic disorders. Vitamin E TPGS micelles containing paliperidone palmitate were prepared by the solvent casting method and control paliperidone palmitate formulations were prepared by simple sonication method. The prepared micelles and control paliperidone palmitate formulations were evaluated for different parameters. Particle sizes of prepared micelles, control paliperidone palmitate formulations were determined at 25 °C by dynamic light scattering technique and external surface morphology was determined by transmission electron microscopy analysis. The encapsulation efficiency was determined by spectrophotometery. In-vitro release studies of micelles and control formulations were carried out by dialysis bag diffusion method. The particle sizes of the paliperidone palmitate-loaded TPGS micelles were 26.5 nm. About 92% of drug encapsulation efficiency was achieved with micelles. The drug release from paliperidone palmitate-loaded TPGS micelles was sustained for more than 24 h with 40% of drug release. The TPGS product, i.e. paliperidone palmitate-loaded micelles, resulted in nano-sized delivery, solubility enhancement and permeability of the micelles which provided an improved and prolonged anti-psychotic effect in comparison to control paliperidone palmitate formulation.

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

    Directory of Open Access Journals (Sweden)

    Guo Q

    2016-11-01

    Full Text Available Qin Guo,1,* Jie Cai,1,2,* Pengyu Li,1 Dongling Xu,1 Xiaomin Ni,1 Hui Wen,3 Dan Liu,3 Suizhen Lin,3 Haiyan Hu1 1School of Pharmaceutical Sciences, Sun Yat-sen University, 2Guangzhou First People’s Hospital, Guangzhou Medical University, 3Guangzhou Cellprotek Pharmaceutical Co., Ltd., Science Park, Guangzhou, People’s Republic of China *These authors contributed equally to this work Abstract: 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

  10. Stepwise-activable multifunctional peptide-guided prodrug micelles for cancerous cells intracellular drug release

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing, E-mail: zhangjing@zjut.edu.cn; Li, Mengfei [Zhejiang University of Technology, College of Materials Science and Engineering (China); Yuan, Zhefan [Zhejiang University, Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Department of Chemical and Biological Engineering (China); Wu, Dan; Chen, Jia-da; Feng, Jie, E-mail: fengjie@zjut.edu.cn [Zhejiang University of Technology, College of Materials Science and Engineering (China)

    2016-10-15

    A novel type of stepwise-activable multifunctional peptide-guided prodrug micelles (MPPM) was fabricated for cancerous cells intracellular drug release. Deca-lysine sequence (K{sub 10}), a type of cell-penetrating peptide, was synthesized and terminated with azido-glycine. Then a new kind of molecule, alkyne modified doxorubicin (DOX) connecting through disulfide bond (DOX-SS-alkyne), was synthesized. After coupling via Cu-catalyzed azide–alkyne cycloaddition (CuAAC) click chemistry reaction, reduction-sensitive peptide-guided prodrug was obtained. Due to the amphiphilic property of the prodrug, it can assemble to form micelles. To prevent the nanocarriers from unspecific cellular uptake, the prodrug micelles were subsequently modified with 2,3-dimethyl maleic anhydride to obtain MPPM with a negatively charged outer shell. In vitro studies showed that MPPM could be shielded from cells under psychological environment. However, when arriving at mild acidic tumor site, the cell-penetrating capacity of MPPM would be activated by charge reversal of the micelles via hydrolysis of acid-labile β-carboxylic amides and regeneration of K{sub 10}, which enabled efficient internalization of MPPM by tumor cells as well as following glutathione- and protease-induced drug release inside the cancerous cells. Furthermore, since the guide peptide sequences can be accurately designed and synthesized, it can be easily changed for various functions, such as targeting peptide, apoptotic peptide, even aptamers, only need to be terminated with azido-glycine. This method can be used as a template for reduction-sensitive peptide-guided prodrug for cancer therapy.Graphical abstractA novel type of stepwise-activable multifunctional peptide-guided prodrug micelles (MPPM) was fabricated for selective drug delivery in cancerous cells. MPPM could be shielded from cells under psychological environment. However, when arriving at mild acidic tumor site, the cell-penetrating capacity of MPPM would

  11. TNYL peptide functional chitosan-g-stearate conjugate micelles for tumor specific targeting

    Directory of Open Access Journals (Sweden)

    Chen FY

    2014-09-01

    Full Text Available Feng-Ying Chen,1 Jing-Jing Yan,1 Han-Xi Yi,2 Fu-Qiang Hu,2 Yong-Zhong Du,2 Hong Yuan,2 Jian You,2 Meng-Dan Zhao1 1Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, People’s Republic of China; 2College of Pharmaceutical Science, Zhejiang University, Hangzhou, People’s Republic of China Abstract: Nowadays, a real challenge in cancer therapy is to design drug delivery systems that can achieve high concentrations of drugs at the target site for improved therapeutic effect with reduced side effects. In this research, we designed and synthesized a homing peptide-(TNYLFSPNGPIA, TNYL modified chitosan-g-stearate (CS polymer micelle (named T-CS for targeting delivery. The peptide displayed specific binding affinity to EphB4 which is a member of the Eph family of receptor tyrosine protein kinases. The amphiphilic polymer T-CS can gather into micelles by themselves in an aqueous environment with a low critical micelle concentration value (91.2 µg/L and nano-scaled size (82.1±2.8 nm. The drug encapsulation efficiency reached 86.43% after loading the hydrophobic drug doxorubicin (DOX. The cytotoxicity of T-CS/DOX against SKOV3 cells was enhanced by approximately 2.3-fold when compared with CS/DOX. The quantitative and qualitative analysis for cellular uptake indicated that TNYL modification can markedly increase cellular internalization in the EphB4-overexpressing SKOV3 cell line, especially with a short incubation time. It is interesting that relatively higher uptake of the T-CS/DOX micelles by SKOV3 cells (positive-EphB4 than A549 cells (negative-EphB4 was observed when the two cells were co-incubated. Furthermore, in vivo distribution experiment using a bilateral-tumor model showed that there was more fluorescence accumulation in the SKOV3 tumor than in the A549 tumor over the whole experiment. These results suggest that TNYL-modified CS micelles may be promising drug carriers as targeting therapy for the EphB4-overexpressing

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-20

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

  13. Glioma-targeting micelles for optical/magnetic resonance dual-mode imaging

    Directory of Open Access Journals (Sweden)

    Zhou Q

    2015-03-01

    Full Text Available Qing Zhou,1,* Ketao Mu,2,* Lingyu Jiang,1 Hui Xie,3 Wei Liu,1 Zhengzheng Li,1 Hui Qi,1 Shuyan Liang,1 Huibi Xu,1 Yanhong Zhu,1 Wenzhen Zhu,2 Xiangliang Yang11National Engineering Research Center for Nanomedicine, College of Life Science and Technology, 2Radiology Department, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 3Department of Information Processing, China Patent Information Center, Wuhan, People’s Republic of China*These authors contributed equally to this workAbstract: Surgical resection is the primary mode for glioma treatment, while gross total resection is difficult to achieve, due to the invasiveness of the gliomas. Meanwhile, the tumor-resection region is closely related to survival rate and life quality. Therefore, we developed optical/magnetic resonance imaging (MRI bifunctional targeted micelles for glioma so as to delineate the glioma location before and during operation. The micelles were constructed through encapsulation of hydrophobic superparamagnetic iron oxide nanoparticles (SPIONs with polyethylene glycol-block-polycaprolactone (PEG-b-PCL by using a solvent-evaporation method, and modified with a near-infrared fluorescent probe, Cy5.5, in addition to the glioma-targeting ligand lactoferrin (Lf. Being encapsulated by PEG-b-PCL, the hydrophobic SPIONs dispersed well in phosphate-buffered saline over 4 weeks, and the relaxivity (r2 of micelles was 215.4 mM–1·s–1, with sustained satisfactory fluorescent imaging ability, which might have been due to the interval formed by PEG-b-PCL for avoiding the fluorescence quenching caused by SPIONs. The in vivo results indicated that the nanoparticles with Lf accumulated efficiently in glioma cells and prolonged the duration of hypointensity at the tumor site over 48 hours in the MR image compared to the nontarget group. Corresponding with the MRI results, the margin of the glioma was clearly demarcated in the fluorescence image

  14. Fluorescence of aminofluoresceins as an indicative process allowing one to distinguish between micelles of cationic surfactants and micelle-like aggregates

    Science.gov (United States)

    Mchedlov-Petrossyan, Nikolay O.; Cheipesh, Tatiana A.; Roshal, Alexander D.; Doroshenko, Andrey O.; Vodolazkaya, Natalya A.

    2016-09-01

    Among the vast set of fluorescein derivatives, the double charged R2- anions of aminofluoresceins are known to exhibit only low quantum yields of fluorescence, \\varphi . The \\varphi value becomes as high as that of the fluorescein dianion when the lone electron pair of the amino group is involved in a covalent bond. According to Munkholm et al (1990 J. Am. Chem. Soc. 112 2608-12), a much smaller increase in the emission intensity can be observed in the presence of surfactant micelles. However, all these observations refer to aqueous or alcoholic solvents. In this paper, we show that in the non-hydrogen bond donor (or ‘aprotic’) solvents DMSO and acetone, the quantum yields, φ, of the 4‧- (or 5‧)-aminofluorescein R2- species amount to 61-67% and approach that of fluorescein (φ  =  87%), whereas in water φ is only 0.6-0.8%. In glycerol, a solvent with an extremely high viscosity, the φ value is only 6-10%. We report on the enhancement of the fluorescence of the aminofluorescein dianions as an indicative process, which allows us to distinguish between the micelle-like aggregates of cationic dendrimers of low generation, common spherical surfactant micelles, and surfactant bilayers. Some of these colloidal aggregates partly restore the fluorescence of aminofluoresceins in aqueous media. By contrast, other positively charged micellar-like aggregates do not enhance the quantum yield of aminofluorescein R2- species. Results for several related systems, such as CTAB-coated SiO2 particles and reverse microemulsions, are briefly described, and the possible reasons for the observed phenomena are discussed.

  15. Micelle-vesicle-micelle transition in aqueous solution of anionic surfactant and cationic imidazolium surfactants: Alteration of the location of different fluorophores.

    Science.gov (United States)

    Dutta, Rupam; Ghosh, Surajit; Banerjee, Pavel; Kundu, Sangita; Sarkar, Nilmoni

    2017-03-15

    The presence of different surfactants can alter the physicochemical behaviors of aqueous organized assemblies. In this article, we have investigated the location of hydrophobic molecule (Coumarin 153, C153) and hydrophilic molecule (Rhodamine 6G perchlorate, R6G) during micelle-vesicle-micelle transition in aqueous medium in presence of anionic surfactant, sodium dodecylbenzenesulfonate (SDBS) and cationic imidazolium-based surfactant, 1-alkyl-3-methylimidazolium chloride (C n mimCl; n=12, 16). Initially, the physicochemical properties of anionic micellar solution of SDBS has been investigated in presence of imidazolium-based surfactant, C n mimCl (n=12, 16) in aqueous medium by visual observation, turbidity measurement, zeta potential (ζ), dynamics light scattering (DLS), and transmission electron microscopy (TEM). Zeta potential (ζ) measurement clearly indicates that the incorporation efficiency of C 16 mimCl in SDBS micelle is better than the other one due to the involvement of strong hydrophobic as well as electrostatic interaction between the two associated molecules. Turbidity and DLS measurements clearly suggest the formation of vesicles over a wide range of concentration. Finally, the rotational motion of C153 and R6G has also been monitored at different mole fractions of C n mimCl in SDBS-C n mimCl (n=12, 16) solution mixtures. The hydrophobic C153 molecules preferentially located in the bilayer region of vesicle, whereas hydrophilic R6G can be solubilized at surface of the bilayer, inner water pool or outer surface of vesicles. It is observed that rotational motion of R6G is altered significantly in SDBS-C n mimCl solution mixtures in presence of different mole fractions of C n mimCl. Additionally, the translational diffusion motion of R6G is monitored using fluorescence correlation spectroscopy (FCS) techniques to get a complete scenario about the location and translational diffusion of R6G. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Detection of Human Sewage in Urban Stormwater Using DNA Based Methods and Stable Isotope Analysis

    Science.gov (United States)

    McLellan, S. L.; Malet, N.; Sauer, E.; Mueller-Spitz, S.; Borchardt, M.

    2008-12-01

    related to the mixed organic matter sources in polluted stormwater runoff, and that this signal will distinct from untreated sanitary sewage. Stable isotope signatures of stormwater and untreated sewage were determined and compared with the rivers. Isotopic values of stormwater was delta 15N = 1.1 ± 2 %; delta 13C = -25.5 ± 3 % and sewage was delta 15N = -1.9 ± 0.2 %; delta 13C = -23.6 ± 0.3. Suspended particular organic matter (SPOM) of Milwaukee River showed depleted delta 13C (-28.6 ± 1.6 %) and enriched delta 15N (7.7 ± 1.9 %) values. SPOM of the KK River exhibited the most depleted delta 15N (0.2 ± 1.6 %) and enriched delta 13C (-24.8 ± 1.8 %) isotopic values. Menomonee River SPOM showed intermediate isotopic values. The delta 13C values of each river and the estuary enriched significantly throughout the summer storm periods. The isotope signals in the KK and Menomonee were indicative of stormwater runoff and sewage contamination. These results suggest that unrecognized sewage inputs are chronically present and may be delivered through urban stormwater systems. DNA based methods combined with isotope analysis may provide a useful tool for urban watershed assessments and to identify sewage inputs. Delineating the relative contribution of stormwater and sewage to overall degraded water quality might give the first indication of the impact of these sources on the Michigan Lake waters.

  17. Biochemical characterization of the interactions between doxorubicin and lipidic GM1 micelles with or without paclitaxel loading

    Directory of Open Access Journals (Sweden)

    Leonhard V

    2015-05-01

    Full Text Available Victoria Leonhard,1,2 Roxana V Alasino,1,2 Ismael D Bianco,1–3 Ariel G Garro,1 Valeria Heredia,1 Dante M Beltramo1,2,4 1Centro de Excelencia en Productos y Procesos de Córdoba (CEPROCOR, Córdoba, Argentina; 2Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, Buenos Aires, Argentina; 3Departamento de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de La Rioja, La Rioja, Argentina; 4Laboratorio de Biotecnología, Facultad de Ciencias Químicas, Universidad Católica de Córdoba, Córdoba, Argentina Abstract: 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

  18. Surfactant-Free Vanadium Oxides from Reverse Micelles and Organic Oxidants: Solution Processable Nanoribbons with Potential Applicability as Battery Insertion Electrodes Assembled in Different Configurations.

    Science.gov (United States)

    Tartaj, Pedro; Amarilla, Jose M; Vazquez-Santos, Maria B

    2015-11-17

    Vanadium oxides similar to other metal transition oxides are prototypes of multifunctionality. Implementing new synthesis routes that lead to dry vanadium oxide nanomaterials with good functional and structural properties as well as good processing capabilities is thus of general interest. Here we report a facile method based on reverse micelles for the growth at room temperature and atmospheric pressure of surfactant-free vanadium oxide nanoribbons that retain after drying excellent solution-processable capabilities. Essential for the success of the method is the use of a soluble organic oxidant that acts as oxidant and cosurfactant during the synthesis, and facilitates surfactant removal with a simple washing protocol. Interestingly, this simple surfactant removal protocol could be of general applicability. As a proof-of-concept of the functional, structural, and processing capabilities of the dry vanadium oxide nanoribbons here prepared, we have checked their lithium insertion capabilities as battery cathodes built upon different configurations. Specifically, we show efficient insertion both in dry nanoribbons processed as films using doctor blade and organic solvents and in dry nanoribbons infiltrated in three-dimensional metal collectors from aqueous suspensions.

  19. Competitive and Synergistic Interactions between Polymer Micelles, Drugs, and Cyclodextrins:The Importance of Drug Solubilization Locus

    OpenAIRE

    Valero, Margarita; Castiglione, Franca; Mele, Andrea; Da Silva, Marcelo A.; Grillo, Isabelle; González-Gaitano, Gustavo; Dreiss, Cécile A.

    2016-01-01

    Polymeric micelles, in particular PEO-PPO-based Pluronic, have emerged as promising drug carriers, while cyclodextrins (CD), cyclic oligosaccharides with an apolar cavity, have long been used for their capacity to form inclusion complexes with drugs. Dimethylated β-cyclodextrin (DIMEB) has the capacity to fully breakup F127 Pluronic micelles, while this effect is substantially hindered if drugs are loaded within the micellar aggregates. Four drugs were studied at physiological temperature: li...

  20. Effect of the additives on clouding behavior and thermodynamics of coenzyme Q10-Kolliphor HS15 micelle aqueous solutions

    Science.gov (United States)

    Hu, Li; Zhang, Jing; Zhu, Chao; Pan, Hong-chun; Liu, Hong

    2017-11-01

    Herein we investigate the effect of different additives (electrolytes, amino acids, PEG, and sugars) on the cloud points (CP) of coenzyme Q10 (CoQ10) - Kolliphor HS15 (HS15) micelle aqueous solutions. The CP values were decreased with the increase of electrolytes and sugars, following: CPAl3+ reduced the CP. A depression of CP for CoQ10-HS15 micelle solution with PEG was molecular weight of PEG dependent. The significant thermodynamic parameters were also evaluated and discussed.

  1. Preparation of stable micelle-like particles with rigid backbones based on pyridyl-terminated poly (aryl ether ketone)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuling; Liu, Lingzhi; Zhang, Limei; Jiang, Zhenhua [Alan G. MacDiarmid Institute, College of Chemistry, Jilin University, Changchun 130012 (China); Wang, Guibin, E-mail: wgb@jlu.edu.cn [Alan G. MacDiarmid Institute, College of Chemistry, Jilin University, Changchun 130012 (China)

    2012-10-15

    A new pyridyl-containing phenol (3-(2-hydroxyphenylimine) pyridine, PY-PH) and pyridyl-terminated poly(aryl ether ketone) (PAEK-py) were first synthesized. Furthermore, micelle-like particles were successfully prepared in a selective solvent (water, H{sub 2}O) based on the graft-like complexes formed by hydrogen-bonding interactions between pyridyl groups of rigid PAEK-py and carboxyl groups of flexible poly(acrylic acid) (PAA) in their common solvent (tetrahydrofuran, THF), as proven by the measurements of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and surface tension. The diameters of the resulted micelle-like particles with PAEK-py as the inner core and PAA as the outer shell were about 100-350 nm. It was found that the formation and size of micelle-like particles depended on pH value and weight ratio of PAEK-py to PAA, respectively. The structure of the micelle-like particles could be stabilized by the cross-linking reaction between pyridyl groups of PAEK-py and 1,4-dibromobutane, and the diameters of the micelle-like particles obviously decreased after the cross-linking reaction due to falling off of the PAA shell of the micelle-like particles. -- Highlights: Black-Right-Pointing-Pointer A new pyridyl-terminated poly(aryl ether ketone) (PAEK-py) were first synthesized. Black-Right-Pointing-Pointer Micelle-like particles based on rigid PAEK-py and flexible PAA were successfully prepared. Black-Right-Pointing-Pointer The structure of the micelle-like particles could be stabilized by the cross-linking reaction.

  2. Bioavailability Enhancement of Paclitaxel via a Novel Oral Drug Delivery System: Paclitaxel-Loaded Glycyrrhizic Acid Micelles

    Directory of Open Access Journals (Sweden)

    Fu-Heng Yang

    2015-03-01

    Full Text Available Paclitaxel (PTX, taxol, a classical antitumor drug against a wide range of tumors, shows poor oral bioavailability. In order to improve the oral bioavailability of PTX, glycyrrhizic acid (GA was used as the carrier in this study. This was the first report on the preparation, characterization and the pharmacokinetic study in rats of PTX-loaded GA micelles The PTX-loaded micelles, prepared with ultrasonic dispersion method, displayed small particle sizes and spherical shapes. Differential scanning calorimeter (DSC thermograms indicated that PTX was entrapped in the GA micelles and existed as an amorphous state. The encapsulation efficiency was about 90%, and the drug loading rate could reach up to 7.90%. PTX-loaded GA micelles displayed a delayed drug release compared to Taxol in the in vitro release experiment. In pharmacokinetic study via oral administration, the area under the plasma concentration-time curve (AUC0→24 h of PTX-loaded GA micelles was about six times higher than that of Taxol (p < 0.05. The significant oral absorption enhancement of PTX from PTX-loaded GA micelles could be largely due to the increased absorption in jejunum and colon intestine. All these results suggested that GA would be a promising carrier for the oral delivery of PTX.

  3. Redox-responsive core cross-linked prodrug micelles prepared by click chemistry for pH-triggered doxorubicin delivery

    Directory of Open Access Journals (Sweden)

    X. T. Cao

    2017-10-01

    Full Text Available A pH-triggered drug delivery system of degradable core cross-linked (CCL prodrug micelles was prepared by click chemistry. Doxorubicin conjugated block copolymers of azido functional poly(ethylene oxide-b-poly(glycidyl methacrylate were synthesized by the combination of RAFT polymerization, epoxide ring-opening reaction, and acid-cleavable hydrazone linkages. The CCL prodrug micelles were produced by the reaction of dipropargyl 3,3′-dithiodipropionate and dipropargyl adipate cross-linking agents with the azido groups of the micellar core via alkyne-azide click reaction, which were denoted as CCL/SS and CCL/noSS, respectively. The TEM images of CCL/SS prodrug micelles showed a spherical shape with the average diameter of 61.0 nm from water, and the shape was maintained with an increased diameter upon dilution with 5-fold DMF. The high DOX conjugation efficiency was 88.4%. In contrast to a very slow DOX release from CCL/SS prodrug micelles under the physiological condition (pH 7.4, the drug release is much faster (90% at pH 5.0 and 10 mM of GSH after 96 h. The cytotoxicity test and confocal laser scanning microscopy analysis revealed that CCL/SS prodrug micelles had much enhanced intracellular drug release capability in HepG2 cells than CCL/noSS prodrug micelles.

  4. Micelle formation of amphiphilic polystyrene-b-poly(N-vinylpyrrolidone) diblock copolymer in methanol and water-methanol binary mixtures.

    Science.gov (United States)

    Hussain, H; Tan, B H; Gudipati, C S; He, C B; Liu, Y; Davis, Thomas P

    2009-05-19

    The micelle formation by the amphiphilic polystyrene-block-poly(N-vinylpyrrolidone) (PS48-b-PNVP99) copolymer is investigated in methanol and water-methanol binary mixtures of various compositions using 1H NMR, fluorescence spectroscopy, static/dynamic light scattering (SLS/DLS), and transmission electron microscopy (TEM). Critical micelle concentrations (cmc) are determined by employing fluorescence spectroscopy and DLS measurements. The cmc of the PS48-b-PNVP99 block copolymer increases with increasing methanol content in the water-methanol binary mixtures, suggesting that methanol is a better solvent for the PS48-b-PNVP99 block copolymer than water-methanol mixtures or pure water. The amphiphilic PS48-b-PNVP99 diblock copolymer forms spherical micelles of Rh approximately 16 nm in pure methanol solution as revealed by DLS measurements. In contrast, significantly larger micelles having higher aggregation numbers are formed in water-methanol binary mixtures. Temperature dependent data reveal an increase in aggregation number and radius of gyration (Rg) concomitantly with temperature (10-40 degrees C). In contrast, the overall size (Rh) of the micelles remains almost constant over the same temperature range. An explanation is tendered that PNVP coronas dehydrate/desolvate at higher temperatures counteracting the increase in micelle size (Rh) caused by increased aggregation numbers (Nagg).

  5. Design strategy of pH-sensitive triblock copolymer micelles for efficient cellular uptake by computer simulations

    Science.gov (United States)

    Xia, Qiang-sheng; Ding, Hong-ming; Ma, Yu-qiang

    2018-03-01

    Efficient delivery of nanoparticles into specific cell interiors is of great importance in biomedicine. Recently, the pH-responsive micelle has emerged as one potential nanocarrier to realize such purpose since there exist obvious pH differences between normal tissues and tumors. Herein, by using dissipative particle dynamics simulation, we investigate the interaction of the pH-sensitive triblock copolymer micelles composed of ligand (L), hydrophobic block (C) and polyelectrolyte block (P) with cell membrane. It is found that the structure rearrangement of the micelle can facilitate its penetration into the lower leaflet of the bilayer. However, when the ligand-receptor specific interaction is weak, the micelles may just fuse with the upper leaflet of the bilayer. Moreover, the ionization degree of polyelectrolyte block and the length of hydrophobic block also play a vital role in the penetration efficiency. Further, when the sequence of the L, P, C beads in the copolymers is changed, the translocation pathways of the micelles may change from direct penetration to Janus engulfment. The present study reveals the relationship between the molecular structure of the copolymer and the uptake of the pH-sensitive micelles, which may give some significant insights into the experimental design of responsive micellar nanocarriers for highly efficient cellular delivery.

  6. A versatile polymer micelle drug delivery system for encapsulation and in vivo stabilization of hydrophobic anticancer drugs.

    Science.gov (United States)

    Rios-Doria, Jonathan; Carie, Adam; Costich, Tara; Burke, Brian; Skaff, Habib; Panicucci, Riccardo; Sill, Kevin

    2012-01-01

    Chemotherapeutic drugs are widely used for the treatment of cancer; however, use of these drugs is often associated with patient toxicity and poor tumor delivery. Micellar drug carriers offer a promising approach for formulating and achieving improved delivery of hydrophobic chemotherapeutic drugs; however, conventional micelles do not have long-term stability in complex biological environments such as plasma. To address this problem, a novel triblock copolymer has been developed to encapsulate several different hydrophobic drugs into stable polymer micelles. These micelles have been engineered to be stable at low concentrations even in complex biological fluids, and to release cargo in response to low pH environments, such as in the tumor microenvironment or in tumor cell endosomes. The particle sizes of drugs encapsulated ranged between 30-80 nm, with no relationship to the hydrophobicity of the drug. Stabilization of the micelles below the critical micelle concentration was demonstrated using a pH-reversible crosslinking mechanism, with proof-of-concept demonstrated in both in vitro and in vivo models. Described herein is polymer micelle drug delivery system that enables encapsulation and stabilization of a wide variety of chemotherapeutic drugs in a single platform.

  7. A Versatile Polymer Micelle Drug Delivery System for Encapsulation and In Vivo Stabilization of Hydrophobic Anticancer Drugs

    Directory of Open Access Journals (Sweden)

    Jonathan Rios-Doria

    2012-01-01

    Full Text Available Chemotherapeutic drugs are widely used for the treatment of cancer; however, use of these drugs is often associated with patient toxicity and poor tumor delivery. Micellar drug carriers offer a promising approach for formulating and achieving improved delivery of hydrophobic chemotherapeutic drugs; however, conventional micelles do not have long-term stability in complex biological environments such as plasma. To address this problem, a novel triblock copolymer has been developed to encapsulate several different hydrophobic drugs into stable polymer micelles. These micelles have been engineered to be stable at low concentrations even in complex biological fluids, and to release cargo in response to low pH environments, such as in the tumor microenvironment or in tumor cell endosomes. The particle sizes of drugs encapsulated ranged between 30–80 nm, with no relationship to the hydrophobicity of the drug. Stabilization of the micelles below the critical micelle concentration was demonstrated using a pH-reversible crosslinking mechanism, with proof-of-concept demonstrated in both in vitro and in vivo models. Described herein is polymer micelle drug delivery system that enables encapsulation and stabilization of a wide variety of chemotherapeutic drugs in a single platform.

  8. Low-Dimensional Nanoparticle Clustering in Polymer Micelles and Their Transverse Relaxivity Rates

    Science.gov (United States)

    Hickey, Robert J.; Meng, Xin; Zhang, Peijun; Park, So-Jung

    2015-01-01

    One- or two-dimensional arrays of iron oxide nanoparticles were formed in colloidal assemblies of amphiphilic polymers. Electron tomography imaging revealed that nanoparticles are arranged into one-dimensional strings in magneto-micelles or two-dimensional sheets in magneto-core/shell assemblies. The distinct directional assembly behavior was attributed to the interparticle interaction relative to the nanoparticle–polymer interaction, which was modulated by varying the cosolvent used for the solution phase self-assembly. Magneto-core/shell assemblies with varying structural parameters were formed with a range of different sized as-synthesized nanoparticles. The transverse magnetic relaxivity rates (r2) of a series of different assemblies were determined to examine the effect of nanoparticle arrangement on the magnetic relaxivity for their potential applications in MRI. The results indicated that the assembly structure of nanoparticles in polymer micelles significantly affects the r2 of surrounding water, providing a way to control magnetic relaxivity. PMID:23731021

  9. Removal of perfluoroalkyl sulfonates (PFAS) from aqueous solution using permanently confined micelle arrays (PCMAs)

    KAUST Repository

    Wang, Fei

    2014-12-01

    One new sorbent with permanently confined micelle arrays (PCMAs) has been synthesized to remove PFAS compounds from aquatic solutions. The TEM and SEM studies showed that large particle sizes with lots of macro-pores and highly order hexagonal structure of cylindrical micelle had been formed in the sorbent. The FTIR spectrums demonstrated the formation of Si-O-Si covalent bond in the new material. The kinetic study showed that the sorption of PFOS, PFHxS, and PFBuS by PCMAs reached equilibrium within 5 min. The pH and salts in solution are found to have limited effects on sorption of PFOS on the new sorbent, and regeneration experiments revealed that PFAS removal efficiencies by the PCMAs did not decrease after 5 cycle regenerations. The high capabilities of PCMAs make it a potentially attractive sorbent for the removal of PFCs from aqueous solution.

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    as a model reaction. The micellar hydrodynamic radius results reflected, to some extent, the redistribution of surfactant and water after enzyme addition, and the correlation between surfactant formulation, water content (W0), micellar size, and enzyme activity. An adequate modification density of CB......Sorbitan trioleate (Span 85) modified by Cibacron Blue F-3GA (CB) was prepared and used as an affinity surfactant to formulate a reversed micellar system for Candida rugosa lipase (CRL) solubilization. The system was characterized and evaluated by employing CRL-catalyzed hydrolysis of olive oil...... was found to be important for the reversed micelles to retain enough hydration capacity and achieve high enzyme activity. Compared with the results in AOT-based reversed micelles, CRL in this micellar system exhibited a different activity behavior versus W0. The optimal pH and temperature...

  11. Assessment of Palmitoyl and Sulphate Conjugated Glycol Chitosan for Development of Polymeric Micelles

    Directory of Open Access Journals (Sweden)

    Ikram Ullah Khan

    2013-06-01

    Full Text Available Introduction: Amphiphilic copolymers are capable of forming core shell-like structures at the critical micellar concentration (CMC; hence, they can serve as drug carriers. Thus, in the present work, polymeric micelles based on novel chitosan derivative were synthesized. Methods: Block copolymer of palmitoyl glycol chitosan sulfate (PGCS was prepared by grafting palmitoyl and sulfate groups serving as hydrophobic and hydrophilic fractions, respectively. Then, fourier transform infrared spectra (FTIR and spectral changes in iodine/iodide mixture were carried out. Results: FTIR studies confirmed the formation of palmitoyl glycol chitosan sulfate (PGCS and spectral changes in iodine/iodide mixture indicated CMC which lies in the range of 0.003-0.2 mg/ml. Conclusion: Therefore, our study indicated that polymeric micelles based on palmitoyl glycol chitosan sulphate could be used as a prospective carrier for water insoluble drugs.

  12. 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.

  13. 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...... associated with the micellar cubic phase, Pm3n and Fd3m. The micellar volumes calculated for these space groups are similar and are consistent with a change in micellar geometry from spherical to prolate....

  14. Polymeric micelles: Theranostic co-delivery system for poorly water-soluble drugs and contrast agents.

    Science.gov (United States)

    Upponi, Jaydev R; Jerajani, Kaushal; Nagesha, Dattatri K; Kulkarni, Praveen; Sridhar, Srinivas; Ferris, Craig; Torchilin, Vladimir P

    2018-03-31

    Interest in theranostic agents has continued to grow because of their promise for simultaneous cancer detection and therapy. A platform-based nanosized combination agent suitable for the enhanced diagnosis and treatment of cancer was prepared using polymeric polyethylene glycol-phosphatidylethanolamine-based micelles loaded with both, poorly soluble chemotherapeutic agent paclitaxel and hydrophobic superparamagnetic iron oxide nanoparticles (SPION), a Magnetic Resonance Imaging contrast agent. The co-loaded paclitaxel and SPION did not affect each other's functional properties in vitro. In vivo, the resulting paclitaxel-SPION-co-loaded PEG-PE micelles retained their Magnetic Resonance contrast properties and apoptotic activity in breast and melanoma tumor mouse models. Such theranostic systems are likely to play a significant role in the combined diagnosis and therapy that leads to a more personalized and effective form of treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. The Organization of Nanoporous Structure Using Controlled Micelle Size from MPEG-b-PDLLA Block Copolymers

    International Nuclear Information System (INIS)

    Chang, Jeong Ho; Kim, Kyung Ja; Shin, Young Kook

    2004-01-01

    Selected MPEG-b-PDLLA block copolymers have been synthesized by ring-opening polymerization with systematic variation of the chain lengths of the resident hydrophilic and hydrophobic blocks. The size and shape of the micelles that spontaneously form in solution are then controlled by the characteristics of the block copolymer template. All the materials prepared in this study showed the tunable pore size of 20-80 A with the increase of hydrophobic chain lengths and up to 660 m 2 /g of specific surface area. The formation mechanism of these nanoporous structures obtained by controlling the micelle size has been confirmed using both liquid and solid state 13 C and 29 Si NMR techniques. This work verifies the formation mechanism of nanoporous structures in which the pore size and wall thickness are closely dependent on the size of hydrophobic cores and hydrophilic shells of the block copolymer templates

  16. Time-resolved small-angle neutron scattering of a micelle-to-vesicle transition

    Energy Technology Data Exchange (ETDEWEB)

    Egelhaaf, S.U. [Institut Max von Laue - Paul Langevin (ILL), 38 -Grenoble (France); Schurtenberger, P. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-04-01

    Amphiphilic molecules spontaneously self-assemble in solution to form a variety of aggregates. Only limited information is available on the kinetics of the structural transitions as well as on the existence of non-equilibrium or metastable states. Aqueous mixtures of lecithin and bile salt are very interesting biological model-systems which exhibit a spontaneous transition from polymer-like mixed micelles to vesicles upon dilution. The small-angle neutron scattering (SANS) instrument D22, with its very high neutron flux and the broad range of scattering vectors covered in a single instrumental setting, allowed us for the first time to perform time-resolved scattering experiments in order to study the micelle-to-vesicle transition. The temporal evolution of the aggregate structures were followed and detailed information was obtained even on molecular length-scales. (author). 5 refs.

  17. DNA Base Excision Repair (BER) and Cancer Gene Therapy: Use of the Human N-mythlpurien DNA Glycosylase (MPG) to Sensitize Breast Cancer Cells to Low Dose Chemotherapy

    National Research Council Canada - National Science Library

    Harvey, Tia

    2003-01-01

    The DNA Base Excision Repair (PER) pathway is responsible for the repair of alkylation and oxidative DNA damage resulting in protection against the deleterious effects of endogenous and exogenous agents encountered on a daily basis...

  18. Pulse radiolysis studies of electron migration in DNA from DNA base-radical anions to nitroacridine intercalators in aqueous solution

    International Nuclear Information System (INIS)

    Anderson, R.F.; Patel, K.B.

    1991-01-01

    The reactions of the aquated electron (e aq - ) with intercalators of high reduction potential (nitracrine and related basic nitroacridines) has been investigated by pulse radiolysis in the presence of DNA in aqueous solution. Under conditions where the majority of the e aq - species react initially with DNA bases (high DNA:drug ratios) a slower subsequent electron transfer to the intercalator was observed. The rate of this intra-complex transfer, expressed as DNA base pairs traversed per second, was in the range (1.2-3.1) x 10 5 base pairs s -1 and increased in order of the one-electron reduction potentials of the DNA-bound intercalators. No transfer was seen to the much less electron affinic des-nitro analogue of the nitroacridines. Only a small proportion of the initial DNA base radicals (≤50%) underwent this intra-complex electron transfer. Even for the most efficient electron trap, nitracrine, the apparent mean electron migration distance was only three base pairs. A slow secondary reduction of nitroacridines [(0.08-5.0) x 10 4 base pairs s -1 ] was also observed with a proportion of the essentially immobile . OH-induced DNA radicals. This secondary reaction may well serve as a measure of the mobility of the DNa-bound intercalators. This study therefore implies a lack of extensive migration of DNA-associated electrons in aqueous solution, although it does not exclude the possibility that more mobile electrons produced by direct ionization of DNA might migrate over large distances. (author)

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

    Science.gov (United States)

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

    2017-04-12

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

  20. Ionic micelles and aromatic additives: a closer look at the molecular packing parameter.

    Science.gov (United States)

    Lutz-Bueno, Viviane; Isabettini, Stéphane; Walker, Franziska; Kuster, Simon; Liebi, Marianne; Fischer, Peter

    2017-08-16

    Wormlike micellar aggregates formed from the mixture of ionic surfactants with aromatic additives result in solutions with impressive viscoelastic properties. These properties are of high interest for numerous industrial applications and are often used as model systems for soft matter physics. However, robust and simple models for tailoring the viscoelastic response of the solution based on the molecular structure of the employed additive are required to fully exploit the potential of these systems. We address this shortcoming with a modified packing parameter based model, considering the additive-surfactant pair. The role of charge neutralization on anisotropic micellar growth was investigated with derivatives of sodium salicylate. The impact of the additives on the morphology of the micellar aggregates is explained from the molecular level to the macroscopic viscoelasticity. Changes in the micelle's volume, headgroup area and additive structure are explored to redefine the packing parameter. Uncharged additives penetrated deeper into the hydrophobic region of the micelle, whilst charged additives remained trapped in the polar region, as revealed by a combination of 1 H-NMR, SAXS and rheological measurements. A deeper penetration of the additives densified the hydrophobic core of the micelle and induced anisotropic growth by increasing the effective volume of the additive-surfactant pair. This phenomenon largely influenced the viscosity of the solutions. Partially penetrating additives reduced the electrostatic repulsions between surfactant headgroups and neighboring micelles. The resulting increased network density governed the elasticity of the solutions. Considering a packing parameter composed of the additive-surfactant pair proved to be a facile means of engineering the viscoelastic response of surfactant solutions. The self-assembly of the wormlike micellar aggregates could be tailored to desired morphologies resulting in a specific and predictable