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Sample records for copolymer micelle-like nanoparticles

  1. PEG-PLA diblock copolymer micelle-like nanoparticles as all-trans-retinoic acid carrier: in vitro and in vivo characterizations

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Qi, Xian Rong; Maitani, Yoshie; Nagai, Tsuneji

    2009-02-01

    The purpose of this study was to characterize the properties in vitro, i.e. release, degradation, hemolytic potential and anticancer activity, and in vivo disposition of all-trans-retinoic acid (ATRA) in rats after administration of ATRA-loaded micelle-like nanoparticles. The amphiphilic block copolymers consisted of a micellar shell-forming mPEG block and a core-forming PLA block. The mPEG-PLA nanoparticles prepared by an acetone volatilization dialysis procedure were identified as having core-shell structure by 1H NMR spectroscopy. Critical association concentration, drug contents, loading efficiency, particle size and ξ potential were evaluated. The release of ATRA from the nanoparticles and the degradation of PLA were found to be mostly associated with the compositions of the nanoparticles. ATRA release was faster at smaller molecular weight of copolymer and lower drug contents. In vitro, the incorporation of ATRA in mPEG-PLA nanoparticles reduced the hemolytic potential of ATRA. Furthermore, anticancer activity of ATRA against HepG2 cell was increased by encapsulation, which showed an enhancement of tumor treatment of ATRA. In vivo, after intravenous injection to rats, the levels of ATRA in the blood stream and the bioavailability were higher for ATRA-loaded mPEG-PLA nanoparticles than those for ATRA solution. In conclusion, the structure of the mPEG-PLA diblock copolymer could be modulated to fit the demand of in vitro and in vivo characterizations of nanoparticles. The mPEG-PLA nanoparticles' loading ATRA have a promising future for injection administration.

  2. Self-assembly of amphiphilic plasmonic micelle-like nanoparticles in selective solvents.

    PubMed

    He, Jie; Huang, Xinglu; Li, Yan-Chun; Liu, Yijing; Babu, Taarika; Aronova, Maria A; Wang, Shouju; Lu, Zhongyuan; Chen, Xiaoyuan; Nie, Zhihong

    2013-05-29

    Amphiphilic plasmonic micelle-like nanoparticles (APMNs) composed of gold nanoparticles (AuNPs) and amphiphilic block copolymers (BCPs) structurally resemble polymer micelles with well-defined architectures and chemistry. The APMNs can be potentially considered as a prototype for modeling a higher-level self-assembly of micelles. The understanding of such secondary self-assembly is of particular importance for the bottom-up design of new hierarchical nanostructures. This article describes the self-assembly, modeling, and applications of APMN assemblies in selective solvents. In a mixture of water/tetrahydrofuran, APMNs assembled into various superstructures, including unimolecular micelles, clusters with controlled number of APMNs, and vesicles, depending on the lengths of polymer tethers and the sizes of AuNP cores. The delicate interplay of entropy and enthalpy contributions to the overall free energy associated with the assembly process, which is strongly dependent on the spherical architecture of APMNs, yields an assembly diagram that is different from the assembly of linear BCPs. Our experimental and computational studies suggested that the morphologies of assemblies were largely determined by the deformability of the effective nanoparticles (that is, nanoparticles together with tethered chains as a whole). The assemblies of APMNs resulted in strong absorption in near-infrared range due to the remarkable plasmonic coupling of Au cores, thus facilitating their biomedical applications in bioimaging and photothermal therapy of cancer. PMID:23642094

  3. Micelle-like Nanoparticles as Carriers for DNA and siRNA

    PubMed Central

    Navarro, Gemma; Pan, Jiayi; Torchilin, Vladimir P.

    2015-01-01

    Gene therapy represents a potential efficient approach of disease prevention and therapy. However, due to their poor in vivo stability, gene molecules need to be associated with delivery systems to overcome extracellular and intracellular barriers and allow access to the site of action. Cationic polymeric nanoparticles are popular carriers for small interfering RNA (siRNA) and DNA-based therapeutics for which efficient and safe delivery are important factors that need to be optimized. Micelle-like nanoparticles (MNP) (half micelles, half polymeric nanoparticles) can overcome some of the disadvantages of such cationic carriers by unifying in one single carrier the best of both delivery systems. In this review, we will discuss how the unique properties of MNP including self-assembly, condensation and protection of nucleic acids, improved cell association and gene transfection, and low toxicity may contribute to the successful application of siRNA- and DNA-based therapeutics into the clinic. Recent developments of MNP involving the addition of stimulus-sensitive functions to respond specifically to pathological or externally applied “triggers” (e.g., temperature, pH or enzymatic catalysis, light, or magnetic fields) will be discussed. Finally, we will overview the use of MNP as two-in-one carriers for the simultaneous delivery of different agents (small molecules, imaging agents) and nucleic acid combinations. PMID:25557580

  4. Flt1 peptide-hyaluronate conjugate micelle-like nanoparticles encapsulating genistein for the treatment of ocular neovascularization.

    PubMed

    Kim, Hyemin; Choi, Jun-Sub; Kim, Ki Su; Yang, Jeong-A; Joo, Choun-Ki; Hahn, Sei Kwang

    2012-11-01

    Flt1 peptide of GNQWFI is an antagonistic peptide for vascular endothelial growth factor receptor 1 (VEGFR1 or Flt1). In this work, Flt1 peptide-hyaluronate (HA) conjugates were successfully synthesized and the resulting micelle-like nanoparticles were exploited to encapsulate genistein, an inhibitor of tyrosine-specific protein kinases, for the treatment of ocular neovascularization. The mean diameter of genistein-loaded Flt1 peptide-HA conjugate micelles was measured to be 172.0±18.7 nm, with a drug-loading efficiency of 40-50%. In vitro release tests of genistein from the genistein-loaded Flt1 peptide-HA conjugate micelles exhibited the controlled release for longer than 24h. In vitro biological activity of genistein/Flt1 peptide-HA micelles was corroborated from the synergistic anti-proliferation of human umbilical vein endothelial cells (HUVECs). Furthermore, we could confirm the anti-angiogenic effect of genistein/Flt1 peptide-HA micelles from the statistically significant suppression of corneal neovascularization in silver nitrate cauterized corneas of SD rats. The retinal vascular hyperpermeability was also drastically reduced by the treatment in diabetic retinopathy model rats. PMID:22824530

  5. Large Amplitude Oscillatory Shear of Block Copolymer Spheres on a Body-Centered Cubic Lattice: Are Micelles Like Metals?

    SciTech Connect

    Torija, Maria A.; Choi, Soo-Hyung; Lodge, Timothy P.; Bates, Frank S.

    2013-03-07

    Small-angle X-ray diffraction experiments have uncovered a remarkable mechanism of grain alignment during plastic deformation of ordered sphere-forming diblock copolymer micelles when subjected to large amplitude dynamic shearing. A nearly monodisperse poly(styrene-b-ethylene-alt-propylene) (SEP) diblock copolymer with block molecular weights of 42,000 and 60,000 was mixed with squalane (C{sub 30}H{sub 62}), an EP selective solvent, at a concentration of 10 wt %. After high temperature annealing, the sample formed an ordered polydomain morphology containing glassy S cores at room temperature. SAXS powder patterns confirm body-centered cubic (BCC) symmetry and reveal the development of a complex array of two-dimensionally resolved Bragg reflections following the application, and cessation, of oscillatory shearing. These diffraction results are interpreted on the basis of the classic mechanism of crystalline slip, which accounts for plastic deformation of ductile materials such as metals. Four distinct slip systems are shown to be active in this work, suggesting a robust basis for deforming and mixing of soft ordered solids.

  6. Skin delivery by block copolymer nanoparticles (block copolymer micelles).

    PubMed

    Laredj-Bourezg, Faiza; Bolzinger, Marie-Alexandrine; Pelletier, Jocelyne; Valour, Jean-Pierre; Rovère, Marie-Rose; Smatti, Batoule; Chevalier, Yves

    2015-12-30

    Block copolymer nanoparticles often referred to as "block copolymer micelles" have been assessed as carriers for skin delivery of hydrophobic drugs. Such carriers are based on organic biocompatible and biodegradable materials loaded with hydrophobic drugs: poly(lactide)-block-poly(ethylene glycol) copolymer (PLA-b-PEG) nanoparticles that have a solid hydrophobic core made of glassy poly(d,l-lactide), and poly(caprolactone)-block-poly(ethylene glycol) copolymer (PCL-b-PEG) nanoparticles having a liquid core of polycaprolactone. In vitro skin absorption of all-trans retinol showed a large accumulation of retinol in stratum corneum from both block copolymer nanoparticles, higher by a factor 20 than Polysorbate 80 surfactant micelles and by a factor 80 than oil solution. Additionally, skin absorption from PLA-b-PEG nanoparticles was higher by one order of magnitude than PCL-b-PEG, although their sizes (65nm) and external surface (water-swollen PEG layer) were identical as revealed by detailed structural characterizations. Fluorescence microscopy of histological skin sections provided a non-destructive picture of the storage of Nile Red inside stratum corneum, epidermis and dermis. Though particle cores had a different physical states (solid or liquid as measured by (1)H NMR), the ability of nanoparticles for solubilization of the drug assessed from their Hildebrand solubility parameters appeared the parameter of best relevance regarding skin absorption. PMID:26602293

  7. Temperature and anion responsive self-assembly of ionic liquid block copolymers coating gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Junbo; Zhao, Jianlong; Wu, Wenlan; Liang, Ju; Guo, Jinwu; Zhou, Huiyun; Liang, Lijuan

    2016-04-01

    In this paper, double hydrophilic ionic liquid block copolymers (ILBCs), poly poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine)]-block-(N-isopropylacrylamide) (PMMPImB-b-PNIPAAm) was first synthesized by reversible additionfragmentation chain transfer (RAFT) and then attached on the surface of gold nanoparticles (Au NPs) via a strong gold-sulfur bonding for preparing hybrid nanoparticles (PMMPImB-b-PNIPAAm-@-Au NPs). The hybrid NPs had a three layers micelle-like structure, including a gold core, thermo-responsive inner shell and anion responsive outer corona. The self-assembling behavior of thermal- and anion-response from shell and corona were respectively investigated by change of temperature and addition of (CF3SO2)2N-. The results showed the hybrid NPs retained a stable dispersion beyond the lower critical solution temperature (LCST) because of the space or electrostatic protecting by outer PMMPImB. However, with increasing concentration of (CF3SO2)2N-, the micellization of self-assembling PMMPImB-b-PNIPAAm-@-Au NPs was induced to form micellar structure containing the core with hydrophobic PMMPImB- (CF3SO2)2N- surrounded by composite shell of Au NPs-PNIPAAm via the anionresponsive properties of ILBCs. These results indicated that the block copolymers protected plasmonic nanoparticles remain self-assembling properties of block copolymers when phase transition from outer corona polymer.

  8. Temperature and anion responsive self-assembly of ionic liquid block copolymers coating gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Junbo; Zhao, Jianlong; Wu, Wenlan; Liang, Ju; Guo, Jinwu; Zhou, Huiyun; Liang, Lijuan

    2016-06-01

    In this paper, double hydrophilic ionic liquid block copolymers (ILBCs), poly poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine)]- block-(N-isopropylacrylamide) (PMMPImB- b-PNIPAAm) was first synthesized by reversible additionfragmentation chain transfer (RAFT) and then attached on the surface of gold nanoparticles (Au NPs) via a strong gold-sulfur bonding for preparing hybrid nanoparticles (PMMPImB- b-PNIPAAm-@-Au NPs). The hybrid NPs had a three layers micelle-like structure, including a gold core, thermo-responsive inner shell and anion responsive outer corona. The self-assembling behavior of thermal- and anion-response from shell and corona were respectively investigated by change of temperature and addition of (CF3SO2)2N-. The results showed the hybrid NPs retained a stable dispersion beyond the lower critical solution temperature (LCST) because of the space or electrostatic protecting by outer PMMPImB. However, with increasing concentration of (CF3SO2)2N-, the micellization of self-assembling PMMPImB- b-PNIPAAm-@-Au NPs was induced to form micellar structure containing the core with hydrophobic PMMPImB-(CF3SO2)2N- surrounded by composite shell of Au NPs-PNIPAAm via the anionresponsive properties of ILBCs. These results indicated that the block copolymers protected plasmonic nanoparticles remain self-assembling properties of block copolymers when phase transition from outer corona polymer.

  9. Block copolymer/ferroelectric nanoparticle nanocomposites

    NASA Astrophysics Data System (ADS)

    Pang, Xinchang; He, Yanjie; Jiang, Beibei; Iocozzia, James; Zhao, Lei; Guo, Hanzheng; Liu, Jin; Akinc, Mufit; Bowler, Nicola; Tan, Xiaoli; Lin, Zhiqun

    2013-08-01

    Nanocomposites composed of diblock copolymer/ferroelectric nanoparticles were formed by selectively constraining ferroelectric nanoparticles (NPs) within diblock copolymer nanodomains via judicious surface modification of ferroelectric NPs. Ferroelectric barium titanate (BaTiO3) NPs with different sizes that are permanently capped with polystyrene chains (i.e., PS-functionalized BaTiO3NPs) were first synthesized by exploiting amphiphilic unimolecular star-like poly(acrylic acid)-block-polystyrene (PAA-b-PS) diblock copolymers as nanoreactors. Subsequently, PS-functionalized BaTiO3 NPs were preferentially sequestered within PS nanocylinders in the linear cylinder-forming polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer upon mixing the BaTiO3 NPs with PS-b-PMMA. The use of PS-b-PMMA diblock copolymers, rather than traditional homopolymers, offers the opportunity for controlling the spatial organization of PS-functionalized BaTiO3 NPs in the PS-b-PMMA/BaTiO3 NP nanocomposites. Selective solvent vapor annealing was utilized to control the nanodomain orientation in the nanocomposites. Vertically oriented PS nanocylinders containing PS-functionalized BaTiO3 NPs were yielded after exposing the PS-b-PMMA/BaTiO3 NP nanocomposite thin film to acetone vapor, which is a selective solvent for PMMA block. The dielectric properties of nanocomposites in the microwave frequency range were investigated. The molecular weight of PS-b-PMMA and the size of BaTiO3 NPs were found to exert an apparent influence on the dielectric properties of the resulting nanocomposites.Nanocomposites composed of diblock copolymer/ferroelectric nanoparticles were formed by selectively constraining ferroelectric nanoparticles (NPs) within diblock copolymer nanodomains via judicious surface modification of ferroelectric NPs. Ferroelectric barium titanate (BaTiO3) NPs with different sizes that are permanently capped with polystyrene chains (i.e., PS-functionalized BaTiO3NPs) were

  10. Effective Interactions and Miscibility of Nanoparticles in Multiblock Copolymer Melts

    DOE PAGESBeta

    Banerjee, Debapriya; Schweizer, Kenneth S

    2015-01-01

    The microscopic Polymer Reference Interaction Site Model theory is employed to study, for the first time, the effective interactions, spatial organization, and miscibility of dilute spherical nanoparticles in non-microphase separating, chemically heterogeneous, compositionally symmetric AB multiblock copolymer melts of varying monomer sequence or architecture. The dependence of nanoparticle wettability on copolymer sequence and chemistry results in interparticle potentials-of-mean force that are qualitatively different from homopolymers. An important prediction is the ability to improve nanoparticle dispersion via judicious choice of block length and monomer adsorption-strengths which control both local surface segregation and chain connectivity induced packing constraints and frustration. The degreemore » of dispersion also depends strongly on nanoparticle diameter relative to the block contour length. Small particles in copolymers with longer block lengths experience a more homopolymer-like environment which renders them relatively insensitive to copolymer chemical heterogeneity and hinders dispersion. Larger particles (sufficiently larger than the monomer diameter) in copolymers of relatively short block lengths provide better dispersion than either a homopolymer or random copolymer. The theory also predicts a novel widening of the miscibility window for large particles upon increasing the overall molecular weight of copolymers composed of relatively long blocks. The influence of a positive chi-parameter in the pure copolymer melt is briefly studied. Quantitative application to fullerenes in specific copolymers of experimental interest is performed, and miscibility predictions are made.« less

  11. Effective Interactions and Miscibility of Nanoparticles in Multiblock Copolymer Melts

    SciTech Connect

    Banerjee, Debapriya; Schweizer, Kenneth S

    2015-01-01

    The microscopic Polymer Reference Interaction Site Model theory is employed to study, for the first time, the effective interactions, spatial organization, and miscibility of dilute spherical nanoparticles in non-microphase separating, chemically heterogeneous, compositionally symmetric AB multiblock copolymer melts of varying monomer sequence or architecture. The dependence of nanoparticle wettability on copolymer sequence and chemistry results in interparticle potentials-of-mean force that are qualitatively different from homopolymers. An important prediction is the ability to improve nanoparticle dispersion via judicious choice of block length and monomer adsorption-strengths which control both local surface segregation and chain connectivity induced packing constraints and frustration. The degree of dispersion also depends strongly on nanoparticle diameter relative to the block contour length. Small particles in copolymers with longer block lengths experience a more homopolymer-like environment which renders them relatively insensitive to copolymer chemical heterogeneity and hinders dispersion. Larger particles (sufficiently larger than the monomer diameter) in copolymers of relatively short block lengths provide better dispersion than either a homopolymer or random copolymer. The theory also predicts a novel widening of the miscibility window for large particles upon increasing the overall molecular weight of copolymers composed of relatively long blocks. The influence of a positive chi-parameter in the pure copolymer melt is briefly studied. Quantitative application to fullerenes in specific copolymers of experimental interest is performed, and miscibility predictions are made.

  12. Computer simulations of block copolymer tethered nanoparticle self-assembly

    NASA Astrophysics Data System (ADS)

    Chan, Elaine R.; Ho, Lin C.; Glotzer, Sharon C.

    2006-08-01

    We perform molecular simulations to study the self-assembly of block copolymer tethered cubic nanoparticles. Minimal models of the tethered nanoscale building blocks (NBBs) are utilized to explore the structures arising from self-assembly. We demonstrate that attaching a rigid nanocube to a diblock copolymer affects the typical equilibrium morphologies exhibited by the pure copolymer. Lamellar and cylindrical phases are observed in both systems but not at the corresponding relative copolymer tether block fractions. The effect of nanoparticle geometry on phase behavior is investigated by comparing the self-assembled structures formed by the tethered NBBs with those of their linear ABC triblock copolymer counterparts. The tethered nanocubes exhibit the conventional triblock copolymer lamellar and cylindrical phases when the repulsive interactions between different blocks are symmetric. The rigid and bulky nature of the cube induces interfacial curvature in the tethered NBB phases compared to their linear ABC triblock copolymer counterparts. We compare our results with those structures obtained from ABC diblock copolymer tethered nanospheres to further elucidate the role of cubic nanoparticle geometry on self-assembly.

  13. Defect Structures in Block Copolymer/Nanoparticle Blends

    NASA Astrophysics Data System (ADS)

    Ryu, Hyung Ju; Bockstaller, Michael

    2009-03-01

    We present a systematic study of the implications of nanoparticle additives on the defect formation in block copolymer/nanoparticle blends (BCP). The morphology of lamellar styrene/isoprene-based di- and triblock copolymers blended with polystyrene-coated gold nanocrystals at various filling fractions was analyzed using electron microscopy using stereology and image reconstruction. Three structural characteristics, i.e. the grain size distribution, grain orientation distribution and grain boundary structure, were analyzed as a function of polymer chain architecture, particle filling fraction and film processing conditions. With increasing particle filling fraction the average anisotropy as well as average grain size is observed to decrease as is the rate of grain growth during thermal annealing. The results are interpreted in terms of the stabilization of grain boundary structures through segregation of particle fillers to the grain boundary regions.

  14. Structural characterization of copolymer embedded magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Nedelcu, G. G.; Nastro, A.; Filippelli, L.; Cazacu, M.; Iacob, M.; Rossi, C. Oliviero; Popa, A.; Toloman, D.; Dobromir, M.; Iacomi, F.

    2015-10-01

    Small magnetic nanoparticles (Fe3O4) were synthesized by co-precipitation and coated by emulsion polymerization with poly(methyl methacrylate-co-acrylic acid) (PMMA-co-AAc) to create surface functional groups that can attach drug molecules and other biomolecules. The coated and uncoated magnetite nanoparticles were stored for two years in normal closed ships and than characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and electron paramagnetic resonance spectroscopy. The solid phase transformation of magnetite to maghemite, as well as an increase in particle size were evidenced for the uncoated nanoparticles. The coated nanoparticles preserved their magnetite structure and magnetic properties. The influences of monomers and surfactant layers on interactions between the magnetic nanoparticles evidenced that the thickness of the polymer has a significant effect on magnetic properties.

  15. Sulfur copolymer for the direct synthesis of ligand-free CdS nanoparticles.

    PubMed

    Martin, Trevor R; Mazzio, Katherine A; Hillhouse, Hugh W; Luscombe, Christine K

    2015-06-30

    Organic coordinating ligands are ubiquitously used to solubilize, stabilize and functionalize colloidal nanoparticles. Aliphatic organic ligands are typically used to control size during the nanoparticle growth period and are used as a high boiling point solvent for solution-based synthesis procedures. However, these aliphatic ligands are typically not well suited for the end use of the nanoparticles, so additional ligand exchange or ligand stripping procedures must be implemented after the nanoparticle synthesis. Herein we present a ligand-free CdS nanoparticle synthesis procedure using a unique sulfur copolymer. The sulfur copolymer is derived from elemental sulfur, which is a cheap and abundant material. This copolymer is used as a sulfur source and high boiling point solvent, which produces stabilized metal-sulfide nanoparticles that are suspended within a sulfur copolymer matrix. The copolymer can then be removed, thereby yielding ligand-free metal-sulfide nanoparticles. PMID:26077505

  16. Sprayable Elastic Conductors Based on Block Copolymer Silver Nanoparticle Composites

    PubMed Central

    2015-01-01

    Block copolymer silver nanoparticle composite elastic conductors were fabricated through solution blow spinning and subsequent nanoparticle nucleation. The reported technique allows for conformal deposition onto nonplanar substrates. We additionally demonstrated the ability to tune the strain dependence of the electrical properties by adjusting nanoparticle precursor concentration or localized nanoparticle nucleation. The stretchable fiber mats were able to display electrical conductivity values as high as 2000 ± 200 S/cm with only a 12% increase in resistance after 400 cycles of 150% strain. Stretchable elastic conductors with similar and higher bulk conductivity have not achieved comparable stability of electrical properties. These unique electromechanical characteristics are primarily the result of structural changes during mechanical deformation. The versatility of this approach was demonstrated by constructing a stretchable light emitting diode circuit and a strain sensor on planar and nonplanar substrates. PMID:25491507

  17. Responsive Block Copolymer and Gold Nanoparticle Hybrid Nanotubes.

    NASA Astrophysics Data System (ADS)

    Chang, Sehoon; Singamaneni, Srikanth; Young, Seth; Tsukruk, Vladimir

    2009-03-01

    We demonstrate the facile fabrication of responsive polymer and metal nanoparticle composite nanotube structures. The nanotubes are comprised of responsive block copolymer, polystyrene-block-poly (2-vinylpyridine) (PS-b-P2VP), and gold nanoparticles. PS-b-P2VP nanotubes were fabricated using porous alumina template and in situ reduction of the gold nanoparticles in P2VP domains. Owing to the pH sensitive nature of P2VP (anionic polymer with a pKa of 3.8), the nanotubes exhibit a dramatic change in topology in response to the changes in the external pH. Furthermore, the gold nanoparticles in the responsive block exhibit a reversible aggregation, causing a reversible change in optical properties such as absorption.

  18. Enzyme cleavable nanoparticles from peptide based triblock copolymers

    NASA Astrophysics Data System (ADS)

    Fuchs, Adrian V.; Kotman, Niklas; Andrieu, Julien; Mailänder, Volker; Weiss, Clemens K.; Landfester, Katharina

    2013-05-01

    A solid-phase synthesis based approach towards protease cleavable polystyrene-peptide-polystyrene triblock copolymers and their formulation to nanoparticulate systems is presented. These nanoparticles are suitable for the optical detection of an enzyme and have the potential for application as a drug delivery system. Two different peptide sequences, one cleaved by trypsin (GFF), the other by hepsin (RQLRVVGG), a protease overexpressed in early stages of prostate cancer, are used as the central part of the triblock. For optical detection a fluorophore-quencher pair is introduced around the cleavage sequence. The solid phase synthesis is conduced such that two identical sequences are synthesized from one branching point. Eventually, carboxy-terminated polystyrene is introduced into the peptide synthesizer and coupled to the amino-termini of the branched sequence. Upon cleavage, a fragment is released from the triblock copolymer, which has the potential for use in drug delivery applications. Conducting the whole synthesis on a solid phase in the peptide synthesizer avoids solubility issues and post-synthetic purification steps. Due to the hydrophobic PS-chains, the copolymer can easily be formulated to form nanoparticles using a nanoprecipitation process. Incubation of the nanoparticles with the respective enzymes leads to a significant increase of the fluorescence from the incorporated fluorophore, thereby indicating cleavage of the peptide sequence and decomposition of the particles.A solid-phase synthesis based approach towards protease cleavable polystyrene-peptide-polystyrene triblock copolymers and their formulation to nanoparticulate systems is presented. These nanoparticles are suitable for the optical detection of an enzyme and have the potential for application as a drug delivery system. Two different peptide sequences, one cleaved by trypsin (GFF), the other by hepsin (RQLRVVGG), a protease overexpressed in early stages of prostate cancer, are used as the

  19. Geometric frustration phases of diblock copolymers in nanoparticles.

    PubMed

    Li, Shiben; Chen, Peng; Zhang, Linxi; Liang, Haojun

    2011-04-19

    The geometric frustration phases are investigated for diblock copolymers in nanoparticles with neutral surfaces using real-space self-consistent field theory. First, a rich variety of geometric frustration phases with specific symmetries are observed in the polymer nanoparticles with invariable diameters by constructing the phase diagrams arranged as the volume fraction and Flory-Huggins interaction parameter. Most of the space in the phase diagram is filled with phases with strong symmetries, such as spherical or cubic symmetries, while a number of asymmetric or axisymmetric phases are located in a narrow space in the diagram. Then the geometric frustration phases are examined systematically for the diblock copolymers with special polymer parameters, and a rich variety of novel frustration phases with multilayered structures are observed by varying the diameters of the nanoparticles. Furthermore, the investigations on the free energies indicate that the transitions between these frustrated phases are first-order, and the formation mechanism of the frustration phases is reasonably elucidated. PMID:21417241

  20. Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix.

    PubMed

    Martin, Trevor R; Mazzio, Katherine A; Hillhouse, Hugh W; Luscombe, Christine K

    2016-01-01

    Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature solvents. These coordinating ligands help solubilize and stabilize the nanoparticles while in solution, and can influence the resulting size and reactivity of the nanoparticles during their formation. Despite the ubiquity of using ligands during synthesis, the presence of aliphatic ligands on the nanoparticle surface can result in a number of problems during the end use of the nanoparticles, necessitating further ligand stripping or ligand exchange procedures. We have developed a way to synthesize cadmium sulfide (CdS) nanoparticles using a unique sulfur copolymer. This sulfur copolymer is primarily composed of elemental sulfur, which is a cheap and abundant material. The sulfur copolymer has the advantages of operating both as a high temperature solvent and as a sulfur source, which can react with a cadmium precursor during nanoparticle synthesis, resulting in the generation of ligand free CdS. During the reaction, only some of the copolymer is consumed to produce CdS, while the rest remains in the polymeric state, thereby producing a nanocomposite material. Once the reaction is finished, the copolymer stabilizes the nanoparticles within a solid polymeric matrix. The copolymer can then be removed before the nanoparticles are used, which produces nanoparticles that do not have organic coordinating ligands. This nascent synthesis technique presents a method to produce metal-sulfide nanoparticles for a wide variety of applications where the presence of organic ligands is not desired. PMID:27167155

  1. Electric-Field-Induced Alignment of Block Copolymer/Nanoparticle Blends

    SciTech Connect

    Liedel, Clemens; Schindler, Kerstin; Pavan, Mariela J.; Lewin, Christian; Pester, Christian W; Ruppel, Markus A; Urban, Volker S; Shenhar, Roy; Boker, Alexander

    2013-01-01

    External electric fi elds readily align birefringent block-copolymer mesophases. In this study the effect of gold nanoparticles on the electric-fi eld-induced alignment of a lamellae-forming polystyrene- block -poly(2-vinylpyridine) copolymer is assessed. Nanoparticles are homogeneously dispersed in the styrenic phase and promote the quantitative alignment of lamellar domains by substantially lowering the critical field strength above which alignment proceeds. The results suggest that the electric-fi eldassisted alignment of nanostructured block copolymer/nanoparticle composites may offer a simple way to greatly mitigate structural and orientational defects of such fi lms under benign experimental conditions.

  2. Morphological Characteristics and Phase Behavior of Nanoparticle-Modified Block Copolymers

    NASA Astrophysics Data System (ADS)

    Bowman, Michelle; Bockstaller, Michael; Rasmussen, Kim; Samseth, Jon; Smith, Steven; Thompson, Russell; Spontak, Richard

    2007-03-01

    Block copolymers exhibit a wealth of nanoscale morphologies that continue to find use in a diverse variety of emergent (nano)technologies. While numerous studies have explored the effects of molecular confinement on such copolymers, few have examined the use of such objects to modify the morphological characteristics and phase behavior of microphase-ordered block copolymers. In this work, a poly(styrene-b-methyl methacrylate) (SM) diblock copolymer has been modified with surface-functionalized fumed silica (FS) and colloidal silica (CS). Dynamic rheological measurements have been conducted on the neat and nanoparticle-modified copolymer to generate a quantitative comparison with SM/FS and SM/CS nanocomposites. Transmission electron microscopy (TEM) and self-consistent field theory (SCFT) calculations have also been performed to further elucidate results obtained via dynamic rheology by establishing the morphological characteristics of the copolymer and the dispersion of the functionalized nanoparticles within the resultant nanocomposites.

  3. Multiscale Control of Hierarchical Structure in Crystalline Block Copolymer Nanoparticles Using Microfluidics.

    PubMed

    Bains, Aman; Cao, Yimeng; Moffitt, Matthew G

    2015-11-01

    Hierarchical semicrystalline block copolymer nanoparticles are produced in a segmented gas-liquid microfluidic reactor with top-down control of multiscale structural features, including nanoparticle morphologies, sizes, and internal crystallinities. Control of multiscale structure on disparate length scales by a single control variable (flow rate) enables tailoring of drug delivery nanoparticle function including release rates. PMID:26305569

  4. Metal Nanoparticle/Block Copolymer Composite Assembly and Disassembly.

    PubMed

    Li, Zihui; Sai, Hiroaki; Warren, Scott C; Kamperman, Marleen; Arora, Hitesh; Gruner, Sol M; Wiesner, Ulrich

    2009-01-01

    Ligand-stabilized platinum nanoparticles (Pt NPs) were self-assembled with poly(isoprene-block-dimethylaminoethyl methacrylate) (PI-b-PDMAEMA) block copolymers to generate organic-inorganic hybrid materials. High loadings of NPs in hybrids were achieved through usage of N,N-di-(2-(allyloxy)ethyl)-N-3-mercaptopropyl-N-3-methylammonium chloride as the ligand, which provided high solubility of NPs in various solvents as well as high affinity to PDMAEMA. From NP synthesis, existence of sub-1 nm Pt NPs was confirmed by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. Estimations of the Pt NP ligand head group density based on HAADF-STEM images and thermogravimetric analysis (TGA) data yielded results comparable to what has been found for alkanethiol self-assembled monolayers (SAMs) on flat Pt {111} surfaces. Changing the volume fraction of Pt NPs in block copolymer-NP composites yielded hybrids with spherical micellar, wormlike micellar, lamellar and inverse hexagonal morphologies. Disassembly of hybrids with spherical, wormlike micellar, and lamellar morphologies generated isolated metal-NP based nano-spheres, cylinders and sheets, respectively. Results suggest the existence of powerful design criteria for the formation of metal-based nanostructures from designer blocked macromolecules. PMID:21103025

  5. Tuning of Polymeric Nanoparticles by Coassembly of Thermoresponsive Polymers and a Double Hydrophilic Thermoresponsive Block Copolymer.

    PubMed

    Zhang, Qilu; Voorhaar, Lenny; Filippov, Sergey K; Yeşil, Berin Fatma; Hoogenboom, Richard

    2016-05-26

    The coassembly behavior of thermoresponsive statistical copolymers and a double hydrophilic block copolymer having a permanently hydrophilic block and a thermoresponsive block is investigated. By adjusting the hydrophilicity of the thermoresponsive statistical copolymers, hybrid nanoparticles are obtained with various ratios of the two species. Importantly, the size of these nanoparticles can be controlled in between 40 and 250 nm dependent on the TCP and the amount of statistical copolymers in the solution. Simultaneous analysis of static and dynamic light scattering data indicates that the possible structure of nanoparticles varies from hard sphere to less compact architecture and most probably depends on a difference between cloud point temperatures of individual components. This developed coassembly method provides a simple platform for the preparation of defined polymeric nanoparticles. PMID:27144970

  6. Star-like copolymer stabilized noble-metal nanoparticle powders.

    PubMed

    Cao, Peng-Fei; Yan, Yun-Hui; Mangadlao, Joey Dacula; Rong, Li-Han; Advincula, Rigoberto

    2016-03-31

    The amphiphilic star-like copolymer polyethylenimine-block-poly(ε-caprolactone) (PEI-b-PCL) was utilized to transfer the pre-synthesized citrate-capped noble metal nanoparticles (NMNPs) from an aqueous layer to an organic layer without any additional reagents. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were utilized to study the assembly of the polymers coated on the surface of the citrate-capped NMNPs. After removing the organic solvent, the polymer-coated NMNPs in powder form (PCP-NMNPs) were obtained. The excellent solubility of the PEI-b-PCL allows the PCP-NMNPs to be easily dispersed in most of the organic solvents without any significant aggregation. Moreover, the good thermal stability and long-term stability make PCP-NMNPs an excellent NMNP-containing hybrid system for different specific applications, such as surface coating, catalysis and thermoplastic processing of nanocomposite materials. PMID:26659728

  7. Ordered porous mesostructured materials from nanoparticle-block copolymer self-assembly

    SciTech Connect

    Warren, Scott; Wiesner, Ulrich; DiSalvo, Jr., Francis J

    2013-10-29

    The invention provides mesostructured materials and methods of preparing mesostructured materials including metal-rich mesostructured nanoparticle-block copolymer hybrids, porous metal-nonmetal nanocomposite mesostructures, and ordered metal mesostructures with uniform pores. The nanoparticles can be metal, metal alloy, metal mixture, intermetallic, metal-carbon, metal-ceramic, semiconductor-carbon, semiconductor-ceramic, insulator-carbon or insulator-ceramic nanoparticles, or combinations thereof. A block copolymer/ligand-stabilized nanoparticle solution is cast, resulting in the formation of a metal-rich (or semiconductor-rich or insulator-rich) mesostructured nanoparticle-block copolymer hybrid. The hybrid is heated to an elevated temperature, resulting in the formation of an ordered porous nanocomposite mesostructure. A nonmetal component (e.g., carbon or ceramic) is then removed to produce an ordered mesostructure with ordered and large uniform pores.

  8. Novel docetaxel-loaded nanoparticles based on PCL-Tween 80 copolymer for cancer treatment

    PubMed Central

    Ma, Yuandong; Zheng, Yi; Zeng, Xiaowei; Jiang, Liqin; Chen, Hongbo; Liu, Ranyi; Huang, Laiqiang; Mei, Lin

    2011-01-01

    Background The formulation of docetaxel available for clinical use (Taxotere®) contains a high concentration of polysorbate 80 (Tween 80). After incorporation of Tween 80 into poly-ɛ-caprolactone (PCL)-Tween 80 copolymer, the relative amount of Tween 80 should be decreased and the advantages of PCL and Tween 80 should be combined. Methods A novel PCL-Tween 80 copolymer was synthesized from ɛ-caprolactone and Tween 80 in the presence of stannous octoate as a catalyst via ring opening polymerization. Two types of nanoparticle formulation were made from commercial PCL and a self-synthesized PCL-Tween 80 copolymer using a modified solvent extraction/evaporation method. Results The nanoparticles were found by field emission scanning electron microscopy to have a spherical shape and be 200 nm in diameter. The copolymers could encapsulate 10% of the drug in the nanoparticles and release 34.9% of the encapsulated drug over 28 days. PCL-Tween 80 nanoparticles could be internalized into the cells and had higher cellular uptake than the PCL nanoparticles. The drug-loaded PCL-Tween 80 nanoparticles showed better in vitro cytotoxicity towards C6 cancer cells than commercial Taxotere at the same drug concentration. Conclusion Nanoparticles using PCL-Tween 80 copolymer as drug delivery vehicles may have a promising outcome for cancer patients. PMID:22114498

  9. Additive-Driven Assembly of Block Copolymer and Nanoparticles: Influence of Nanoparticle Size and Loading

    NASA Astrophysics Data System (ADS)

    Gai, Yue; Lin, Ying; Watkins, James

    2015-03-01

    Additive-driven assembly of block copolymer (BCP)/nanoparticle (NP) composites in which functionalized NPs exhibiting strong hydrogen bond interactions with one domain of the BCP has been shown to strengthen phase segregation and yield well-ordered materials at high NP loadings. Here we report a systemic study of how phase behavior and NP distribution in BCP/ Au NP composites are influenced by the NP size, NP loading and block copolymer domain size. 2nm, 5nm, 9nm and 15nm diameter Au nanoparticles at loadings ranging from 10% to 50% weight percent, in polystyrene-block-poly (2-vinyl pyridine) block copolymers with domain spacing ranging from 14 nm to 75 nm were used in the investigation. We find that strong interactions enable the incorporation of larger diameter NPs with respect to domain size as compared to systems in which interactions between the NP and BCP are weak or enthalpically neutral. This work was supported by NSF Center for Hierarchical Manufacturing at the University of Massachusetts, Amherst.

  10. Nano- and microstructures of magnetic field-guided maghemite nanoparticles in diblock copolymer films.

    PubMed

    Yao, Yuan; Metwalli, Ezzeldin; Niedermeier, Martin A; Opel, Matthias; Lin, Chen; Ning, Jing; Perlich, Jan; Roth, Stephan V; Müller-Buschbaum, Peter

    2014-04-01

    The control over the alignment of nanoparticles within a block copolymer matrix was investigated for different external magnetic fields with respect to producing well-aligned, highly oriented metal-oxide-polymer nanopatterns. Hybrid films were prepared by solution casting under a range of external magnetic fields. The nano- and microstructure of maghemite nanoparticles within poly(styrene-b-methyl methacrylate) diblock copolymer films as a function of the nanoparticle concentration was studied using optical microscopy, atomic force microscopy, scanning electron microscopy, and grazing incidence small-angle X-ray scattering. Because of a polystyrene (PS) coating, the nanoparticles are incorporated in the PS domains of the diblock copolymer morphology. At higher nanoparticle concentrations, nanoparticle aggregates perturb the block copolymer structure and accumulate at the films surface into wire-shaped stripes. These wire-shaped nanoparticle aggregates form mainly because of the competition between nanoparticle-polymer friction and magnetic dipolar interaction. The magnetic behavior of the hybrid films was probed at different temperatures for two orthogonal directions (with the line-shaped particle aggregates parallel and perpendicular to the magnetic field). The hybrid film systems show superparamagnetic behavior and remarkable shape anisotropy that render them interesting for magnetic applications. PMID:24621173

  11. Star-like copolymer stabilized noble-metal nanoparticle powders

    NASA Astrophysics Data System (ADS)

    Cao, Peng-Fei; Yan, Yun-Hui; Mangadlao, Joey Dacula; Rong, Li-Han; Advincula, Rigoberto

    2016-03-01

    The amphiphilic star-like copolymer polyethylenimine-block-poly(ε-caprolactone) (PEI-b-PCL) was utilized to transfer the pre-synthesized citrate-capped noble metal nanoparticles (NMNPs) from an aqueous layer to an organic layer without any additional reagents. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were utilized to study the assembly of the polymers coated on the surface of the citrate-capped NMNPs. After removing the organic solvent, the polymer-coated NMNPs in powder form (PCP-NMNPs) were obtained. The excellent solubility of the PEI-b-PCL allows the PCP-NMNPs to be easily dispersed in most of the organic solvents without any significant aggregation. Moreover, the good thermal stability and long-term stability make PCP-NMNPs an excellent NMNP-containing hybrid system for different specific applications, such as surface coating, catalysis and thermoplastic processing of nanocomposite materials.The amphiphilic star-like copolymer polyethylenimine-block-poly(ε-caprolactone) (PEI-b-PCL) was utilized to transfer the pre-synthesized citrate-capped noble metal nanoparticles (NMNPs) from an aqueous layer to an organic layer without any additional reagents. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were utilized to study the assembly of the polymers coated on the surface of the citrate-capped NMNPs. After removing the organic solvent, the polymer-coated NMNPs in powder form (PCP-NMNPs) were obtained. The excellent solubility of the PEI-b-PCL allows the PCP-NMNPs to be easily dispersed in most of the organic solvents without any significant aggregation. Moreover, the good thermal stability and long-term stability make PCP-NMNPs an excellent NMNP-containing hybrid system for different specific applications, such as surface coating, catalysis and thermoplastic processing of nanocomposite materials. Electronic supplementary information (ESI) available: Synthesis scheme and the 1H NMR spectrum of PEI

  12. Hydrophilic Monodisperse Magnetic Nanoparticles Protected by an Amphiphilic Alternating Copolymer

    PubMed Central

    Shtykova, Eleonora V.; Huang, Xinlei; Gao, Xinfeng; Dyke, Jason C.; Schmucker, Abrin L.; Dragnea, Bogdan; Remmes, Nicholas; Baxter, David V.; Stein, Barry; Konarev, Peter V.; Svergun, Dmitri I.; Bronstein, Lyudmila M.

    2009-01-01

    Iron oxide nanoparticles (NPs) with diameters of 16.1, 20.5, and 20.8 nm prepared from iron oleate precursors were coated with poly(maleic acid-alt-1-octadecene) (PMAcOD). The coating procedure exploited hydrophobic interactions of octadecene and oleic acid tails while hydrolysis of maleic anhydride moieties allowed the NP hydrophilicity. The PMAcOD nanostructure in water and the PMAcOD-coated NPs were studied using transmission electron microscopy, ζ-potential measurements, small-angle X-ray scattering, and fluorescence measurements. The combination of several techniques suggests that independently of the iron oxide core and oleic acid shell structures, PMAcOD encapsulates NPs, forming stable hydrophilic shells which withstand absorption of hydrophobic molecules, such as pyrene, without shell disintegration. Moreover, the PMAcOD molecules are predominantly attached to a single NP instead of self-assembling into the PMAcOD disklike nanostructures or attachment to several NPs. This leads to highly monodisperse aqueous samples with only a small fraction of NPs forming large aggregates due to cross-linking by the copolymer macromolecules. PMID:19194520

  13. Aluminum nanoparticle/acrylate copolymer nanocomposites for dielectric elastomers with high dielectric constants

    NASA Astrophysics Data System (ADS)

    Hu, Wei; Zhang, Suki N.; Niu, Xiaofan; Liu, Chao; Pei, Qibing

    2014-03-01

    Dielectric elastomers are useful for large-strain actuation and energy harvesting. Their application has been limited by their low dielectric constants and consequently high driving voltage. Various fillers with high dielectric constants have been incorporated into different elastomer systems to improve the actuation strain, force output and energy density of the compliant actuators and generators. However, agglomeration may happen in these nanocomposites, resulting in a decrease of dielectric strength, an increase of leakage current, and in many instances the degree of enhancement of the dielectric constant. In this work, we investigated aluminum nanoparticles as nanofillers for acrylate copolymers. This metallic nanoparticle was chosen because the availability of free electrons could potentially provide an infinite value of dielectric constant as opposed to dielectric materials including ferroelectric nanocrystals. Moreover, aluminum nanoparticles have a self-passivated oxide shell effectively preventing the formation of conductive path. The surfaces of the aluminum nanoparticles were functionalized with methacrylate groups to assist the uniform dispersion in organic solutions and additionally enable copolymerization with acrylate copolymer matrix during bulk polymerization, and thus to suppress large range drifting of the nanoparticles. The resulting Al nanoparticle-acrylate copolymer nanocomposites were found to exhibit higher dielectric constant and increased stiffness. The leakage current under high electric fields were significantly lower than nanocomposites synthesized without proper nanoparticle surface modification. The dielectric strengths of the composites were comparable with the pristine polymers. In dielectric actuation evaluation, the actuation force output and energy specific work density were enhanced in the nanocomposites compared to the pristine copolymer.

  14. Structure, Mechanics, and Transport in Block Copolymer-Nanoparticle Composites at the Macroscopic and Nanometer Lengthscales

    NASA Astrophysics Data System (ADS)

    Cheng, Vicki Alice

    2013-08-01

    Pluronic triblock copolymers self-assemble in water to form thermoreversible soft solids that comprise of periodically spaced micelles. The interstitial spacings of these micellar crystals are on the order of tens of nanometers, and have been used to template comparably sized nanoparticles with hydrodynamic diameters (Dh) ranging from 4-7 nm. Here, nanoparticle diffusivity is studied and modeled in these self-assembling block copolymers across a range of polymer concentrations. Transport in the disordered micellar solution is described as diffusion through a polymer solution, while diffusive behavior in the structured micellar phase is modeled as an activated hopping process. The effects of protein loading, shear alignment, particle type, and block copolymer composition on particle transport are also examined, and they affect particle diffusivity to varying degrees. Block copolymer architecture influences the micellar structure and dimensions, which in turn affects protein templating and protein aggregation behavior. The overall micellar dimensions are smaller in block copolymers with shorter block lengths, and efforts to template particles which are larger than the interstitial spacings result in changes to the block copolymer structure and mechanics. It is possible, however, for block copolymers to accommodate a limited amount of particles which are larger than the estimated micellar interstitial site. When examining protein aggregation behavior in block copolymers with varying PEO chain lengths, striking differences in aggregation behavior are observed as well. Ultimately, this work underscores the interplay between the structure, mechanics, and transport behavior in nanoparticle-block copolymer composites, and this knowledge can be applied towards the design of self-assembling nanoscale materials.

  15. Organization of nanoparticles on hard substrates using block copolymer films as templates.

    PubMed

    Minelli, Caterina; Geissbuehler, Isabelle; Hinderling, Christian; Heinzelmann, Harry; Vogel, Horst; Pugin, Raphael; Liley, Martha

    2006-06-01

    We present a technique for the organization of pre-synthesized nanoparticles on hard substrates, using block copolymer films as sacrificial templates. A thin block copolymer film is dip-coated on the substrate of interest and the sample is exposed to a solution containing nanoparticles. Spontaneous preferential adsorption of the nanoparticles on one phase of the block copolymer film results in their lateral organization. An oxygen plasma etch is used to remove the polymer film; the nanoparticles end up organized on the substrate. We demonstrate that this is a general approach for the patterning of inorganic nanoparticles on hard substrates, showing the organization of metal and semiconductor nanoparticles having different chemistries at the particle/solvent and solvent/polymer interfaces. The nanoparticle patterns that we present have typical periodicities in the nanometer scale. In some cases, microcontact printing is used to create a double length scale of organization, on the micrometer and on the nanometer level. The characteristic periodicity of the template is studied with respect to the nanoparticle size in order to optimize the organization. Finally, we describe how to extend this technique for the production of continuous gold nanowires on hard substrates. We expect that the flexibility of this approach and the degree of control that can be obtained over nanoparticle organization should make it a powerful tool for nanoscale fabrication. PMID:17025059

  16. Drug nanoparticles by emulsion-freeze-drying via the employment of branched block copolymer nanoparticles.

    PubMed

    Wais, Ulrike; Jackson, Alexander W; Zuo, Yanming; Xiang, Yu; He, Tao; Zhang, Haifei

    2016-01-28

    A large percentage of drug compounds exhibit low water solubility and hence low bioavailability and therapeutic efficacy. This may be addressed by preparation of drug nanoparticles, leading to enhanced dissolution rate and direct use for treatment. Various methods have been developed to produce drug nanocrystals, including wet milling, homogenization, solution precipitation, emulsion diffusion, and the recently developed emulsion freeze-drying. The drawback for these methods may include difficult control in particles size, use of surfactants & polymer, and low ratio of drug to stabilizer. Here, biocompatible branched block copolymer nanoparticles with lightly-crosslinked hydrophobic core and hydrophilic surface groups are synthesized by the direct monomer-to-particle methodology, characterized, and then used as scaffold polymer/surfactant to produce drug nanoparticles via the emulsion-freeze-drying approach. This method can be used for model organic dye and different poorly water-soluble drugs. Aqueous drug nanoparticle dispersions can be obtained with high ratio of drug to stabilizer and relatively uniform nanoparticle sizes. PMID:26704935

  17. Preparation of transition metal nanoparticles and surfaces modified with (co)polymers synthesized by RAFT

    DOEpatents

    McCormick, III, Charles L.; Lowe, Andrew B.; Sumerlin, Brent S.

    2011-12-27

    A new, facile, general one-phase method of generating thiol-functionalized transition metal nanoparticles and surfaces modified by (co)polymers synthesized by the RAFT method is described. The method includes the steps of forming a (co)polymer in aqueous solution using the RAFT methodology, forming a colloidal transition metal precursor solution from an appropriate transition metal; adding the metal precursor solution or surface to the (co)polymer solution, adding a reducing agent into the solution to reduce the metal colloid in situ to produce the stabilized nanoparticles or surface, and isolating the stabilized nanoparticles or surface in a manner such that aggregation is minimized. The functionalized surfaces generated using these methods can further undergo planar surface modifications, such as functionalization with a variety of different chemical groups, expanding their utility and application.

  18. Preparation of transition metal nanoparticles and surfaces modified with (CO)polymers synthesized by RAFT

    DOEpatents

    McCormick, III., Charles L.; Lowe, Andrew B.; Sumerlin, Brent S.

    2006-11-21

    A new, facile, general one-phase method of generating thio-functionalized transition metal nanoparticles and surfaces modified by (co)polymers synthesized by the RAFT method is described. The method includes the stops of forming a (co)polymer in aqueous solution using the RAFT methodology, forming a colloidal transition metal precursor solution from an appropriate transition metal; adding the metal precursor solution or surface to the (co)polymer solution, adding a reducing agent into the solution to reduce the metal colloid in situ to produce the stabilized nanoparticles or surface, and isolating the stabilized nanoparticles or surface in a manner such that aggregation is minimized. The functionalized surfaces generated using these methods can further undergo planar surface modifications, such as functionalization with a variety of different chemical groups, expanding their utility and application.

  19. From multi-responsive tri- and diblock copolymers to diblock-copolymer-decorated gold nanoparticles: the effect of architecture on micellization behaviors in aqueous solutions.

    PubMed

    Song, Lichun; Sun, Hui; Chen, Xiaolu; Han, Xia; Liu, Honglai

    2015-06-28

    This work reports on the aqueous stimuli-responsive behaviors of an ABA triblock copolymer, a BAB triblock copolymer, an AB diblock copolymer and citrate-based gold nanoparticles decorated with AB diblock copolymers (where A is the pH- and thermo-responsive poly[N,N-(dimethylamino)ethyl methacrylate] (PDMAEMA) and B is the thermo-responsive poly[2-(2-methoxyethoxy)ethyl methacrylate] (PMEO2MA)). The symmetric triblock polymers were synthesized via sequential atom transfer radical polymerization (ATRP) using a disulfide-functionalized initiator. Subsequently, the thiol-ended diblock copolymers were facilely obtained by reducing these triblock copolymers and were grafted onto gold nanoparticle (AuNP) surfaces via ligand exchange to yield stimuli-sensitive gold nanoparticles (Au@AB and Au@BA). The ABA and BAB triblock copolymers exhibited two-step thermo-induced aggregation behavior in water at a pH near the isoelectric point (IEP), which resulted in the formation of micelles after the first lower critical solution temperature (LCST) and large aggregates consisting of clustered micelles above the second LCST transition. The significant difference between the micelle sizes of the ABA and BAB copolymers, such that the micelle size of the BAB copolymer was smaller than that of the ABA copolymer although both had a similar unit composition, suggests a distinction between the micelle structures. The "branch" and "flower-like" micelles that are formed in the ABA and BAB aqueous solutions, respectively, ultimately governed the phase transition behaviors. The AB diblock copolymer exhibited similar micellization behavior and a micelle size roughly similar to that of the ABA triblock copolymer, although the chain length of the AB copolymer is only half that of the ABA copolymer. Both Au@PDMAEMA-PMEO2MA and Au@PMEO2MA-PDMAEMA showed similar dual LCST behaviors and pH-responsive behaviors in aqueous solutions without the addition of salt. A significant difference was observed

  20. Biological materials: Part A. tuning LCST of raft copolymers and gold/copolymer hybrid nanoparticles and Part B. Biobased nanomaterials

    NASA Astrophysics Data System (ADS)

    Chen, Ning

    The research described in this dissertation is comprised of two major parts. The first part studied the effects of asymmetric amphiphilic end groups on the thermo-response of diblock copolymers of (oligo/di(ethylene glycol) methyl ether (meth)acrylates, OEGA/DEGMA) and the hybrid nanoparticles of these copolymers with a gold nanoparticle core. Placing the more hydrophilic end group on the more hydrophilic block significantly increased the cloud point compared to a similar copolymer composition with the end group placement reversed. For a given composition, the cloud point was shifted by as much as 28 °C depending on the placement of end groups. This is a much stronger effect than either changing the hydrophilic/hydrophobic block ratio or replacing the hydrophilic acrylate monomer with the equivalent methacrylate monomer. The temperature range of the coil-globule transition was also altered. Binding these diblock copolymers to a gold core decreased the cloud point by 5-15 °C and narrowed the temperature range of the coil-globule transition. The effects were more pronounced when the gold core was bound to the less hydrophilic block. Given the limited numbers of monomers that are approved safe for in vivo use, employing amphiphilic end group placement is a useful tool to tune a thermo-response without otherwise changing the copolymer composition. The second part of the dissertation investigated the production of value-added nanomaterials from two biorefinery "wastes": lignin and peptidoglycan. Different solvents and spinning methods (melt-, wet-, and electro-spinning) were tested to make lignin/cellulose blended and carbonized fibers. Only electro-spinning yielded fibers having a small enough diameter for efficient carbonization (≤ 5-10 μm), but it was concluded that cellulose was not a suitable binder. Cellulose lignin fibers before carbonization showed up to 90% decrease in moisture uptake compared to pure cellulose. Peptidoglycan (a bacterial cell wall

  1. "Hairy" Nanoparticles in Block Copolymers and Homopolymers: Modeling using Hybrid Self-Consistent Field Theory

    NASA Astrophysics Data System (ADS)

    Ginzburg, Valeriy

    2011-03-01

    Today, dispersed nanoparticles play important role in various applications (toughened plastics, healthcare, personal care, etc.) Mesoscale simulations and theory are important in understanding what governs the morphology of nanoparticles under various conditions. In particular, for nanoparticle/block copolymer mixtures, two popular simulation methods are Self-Consistent Field/Density Functional Theory (SCF-DFT) (Thompson, Ginzburg, Matsen, and Balazs, Science 292, 2469 [2001]), and Hybrid Self-Consistent Field Theory (HSCFT) (Sides et al., Phys Rev Lett 96, 250601 [2006]). The two methods are shown to be very similar in their assumptions and end-results; the choice of the method to be used can depend on the specific problem. Here, we use modified HSCFT to explicitly account for the complicated role of short-chain ligands grafted onto nanoparticles to promote dispersion. In particular, we discuss the phase diagrams of such ``hairy'' nanoparticles in diblock copolymers as function of diblock composition, nanoparticle volume fraction, and ligand length. Depending on the particle size and ligand coverage, particles could segregate into favorable domain, stay close to the interface, or phase-separate from the block copolymer altogether. We also consider the dispersion of ``hairy'' nanoparticles in a homopolymer and analyze the morphologies of particle clusters as function of ligand length. The results could have interesting implications for the design of new nanocomposite materials.

  2. Assembly of diblock copolymer grafted nanoparticles in a homopolymer blend matrix

    NASA Astrophysics Data System (ADS)

    Estridge, Cara; Jayaraman, Arthi

    2014-03-01

    Hybrid materials comprised of nanoscale fillers embedded in a polymer matrix, also terms polymer nanocomposites, are used in many applications, such as photovoltaics, photonics, automobile parts, where their macroscopic properties are governed by the nanocomposite morphology. The structure and composite morphology is controlled by the interactions of the nanoscale fillers and the polymer matrix. In this talk we show using molecular simulations that functionalization of the nanoparticle surface with AB diblock copolymer grafts is a way to tune the interactions between the grafted particle and the A and B homopolymer blend matrix. Specifically, our work demonstrates that by tailoring the copolymer composition and the copolymer grafting density one can tune the location of the copolymer grafted particles in the matrix, (e.g. within a domain versus interface of two domains). Additionally, in the case where the grafted particles locate themselves at the interface between the two domains, the interfacial tension is reduced below that possible with bare ungrafted particles at the interface.

  3. Functionalized organic nanoparticles from core-crosslinked poly(4-vinylbenzocyclobutene-b-butadiene) diblock copolymer micelles

    SciTech Connect

    Sakellariou, Georgios; Avgeropoulos, Apostolos; Hadjichristidis, Nikos; Mays, Jimmy; Baskaran, Durairaj

    2009-01-01

    Sufface-functionalized polymeric nanoparticles were prepared by: a) self~assembly of poly(4-vinylbenzocyclobutene-b-butadiene) diblock copolymer (PVBCB-b-PB) to form spherical micelles (diameter:15-48 nm) in decane, a selective solvent for PB, b) crosslinking of the PVBCB core through thermal dimerization at 200-240 ~ C, and c) cleavage of the PB corona via ozonolysis and addition of dimethyl sulfide to afford aldehyde-functionalized nanoparticles (diameter: -16-20 nm), along with agglomerated nanoparticles ranging from - 30 to -100 nm in diameter. The characterization of the diblock copolymer precursors. the intermediate micelles and the final surface-functionalized crosslinked nanoparticles was carried alit by a combination of size exclusion chromatography, static and dynamic light scattering, viscometry, thermogravimetric analysis, 1 H NMR and FfIR spectroscopy and transmission electron microscopy.

  4. Poly(trimethylene carbonate)/Poly(malic acid) Amphiphilic Diblock Copolymers as Biocompatible Nanoparticles.

    PubMed

    Barouti, Ghislaine; Khalil, Ali; Orione, Clement; Jarnouen, Kathleen; Cammas-Marion, Sandrine; Loyer, Pascal; Guillaume, Sophie M

    2016-02-18

    Amphiphilic polycarbonate-poly(hydroxyalkanoate) diblock copolymers, namely, poly(trimethylene carbonate) (PTMC)-b-poly(β-malic acid) (PMLA), are reported for the first time. The synthetic strategy relies on commercially available catalysts and initiator. The controlled ring-opening polymerization (ROP) of trimethylene carbonate (TMC) catalyzed by the organic guanidine base 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), associated with iPrOH as an initiator, provided iPrO-PTMC-OH, which served as a macroinitiator in the controlled ROP of benzyl β-malolactonate (MLABe) catalyzed by the neodymium triflate salt (Nd(OTf)3). The resulting hydrophobic iPrO-PTMC-b-PMLABe-OH copolymers were then hydrogenolyzed into the parent iPrO-PTMC-b-PMLA-OH copolymers. A range of well-defined copolymers, featuring different sizes of segments (Mn,NMR up to 9300 g mol(-1) ; ÐM =1.28-1.40), were thus isolated in gram quantities, as evidenced by NMR spectroscopy, size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry, and contact angle analyses. Subsequently, PTMC-b-PMLA copolymers with different hydrophilic weight fractions (11-75 %) self-assembled in phosphate-buffered saline upon nanoprecipitation into well-defined nano-objects with Dh =61-176 nm, a polydispersity index <0.25, and a negative surface charge, as characterized by dynamic light scattering and zeta-potential analyses. In addition, these nanoparticles demonstrated no significant effect on cell viability at low concentrations, and a very low cytotoxicity at high concentrations only for PTMC-b-PMLA copolymers exhibiting hydrophilic fractions over 47 %, thus illustrating the potential of these copolymers as promising nanoparticles. PMID:26791328

  5. Bimetallic PdAg nanoparticle arrays from monolayer films of diblock copolymer micelles

    NASA Astrophysics Data System (ADS)

    Ehret, E.; Beyou, E.; Mamontov, G. V.; Bugrova, T. A.; Prakash, S.; Aouine, M.; Domenichini, B.; Cadete Santos Aires, F. J.

    2015-07-01

    The self-assembly technique provides a highly efficient route to generate well-ordered structures on a nanometer scale. In this paper, well-ordered arrays of PdAg alloy nanoparticles on flat substrates with narrow distributions of particle size (6-7 nm) and interparticle spacing (about 60 nm) were synthesized by the block copolymer micelle approach. A home-made PS-b-P4VP diblock copolymer was prepared to obtain a micellar structure in toluene. Pd and Ag salts were then successfully loaded in the micellar core of the PS-b-P4VP copolymer. A self-assembled monolayer of the loaded micelles was obtained by dipping the flat substrate in the solution. At this stage, the core of the micelles was still loaded with the metal precursor rather than with a metal. Physical and chemical reducing methods were used to reduce the metal salts embedded in the P4VP core into PdAg nanoparticles. HRTEM and EDX indicated that Pd-rich PdAg alloy nanoparticles were synthesized by chemical or physical reduction; UV-visible spectroscopy observations confirmed that metallic PdAg nanoparticles were quickly formed after chemical reduction; XPS measurements revealed that the PdAg alloy nanoparticles were in a metallic state after a short time of exposure to O2 plasma and after hydrazine reduction.

  6. Effect of copolymer composition on the physicochemical characteristics, in vitro stability, and biodistribution of PLGA-mPEG nanoparticles.

    PubMed

    Avgoustakis, K; Beletsi, A; Panagi, Z; Klepetsanis, P; Livaniou, E; Evangelatos, G; Ithakissios, D S

    2003-06-18

    The physicochemical properties, the colloidal stability in vitro and the biodistribution properties in mice of different PLGA-mPEG nanoparticle compositions were investigated. The nanoparticles were prepared by a precipitation-solvent evaporation technique. The physical characteristics and the colloidal stability of the PLGA-mPEG nanoparticles were significantly influenced by the composition of the PLGA-mPEG copolymer used to prepare the nanoparticles. PLGA-mPEG nanoparticles prepared from copolymers having relatively high mPEG/PLGA ratios were smaller and less stable than those prepared from copolymers having relatively low mPEG/PLGA ratios. All PLGA-mPEG nanoparticle compositions exhibited prolonged residence in blood, compared to the conventional PLGA nanoparticles. The composition of the PLGA-mPEG copolymer affected significantly the blood residence time and the biodistribution of the PLGA-mPEG nanoparticles in liver, spleen and bones. The in vivo behavior of the different PLGA-mPEG nanoparticle compositions did not appear to correlate with their in vitro stability. Optimum mPEG/PLGA ratios appeared to exist leading to long blood circulation times of the PLGA-mPEG nanoparticles. This may be associated with the effects of the mPEG/PLGA ratio on the density of PEG on the surface of the nanoparticles and on the size of the nanoparticles. PMID:12787641

  7. Synthesis and graphoepitaxial placement control of block copolymer mediated silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Kim, Dong Wook; Arellano, Noel; Rettner, Charles; Krupp, Leslie; Topuria, Teya; Rice, Philip; Raino, Gabriele; Stoferle, Thilo; Mahrt, Rainer; Kim, Ho-Cheol; Krict Team; Ibm Zurich Research Center Team

    2011-03-01

    The strong interactions of plasmons in metal nanoparticle assemblies can render many possible applications ranging from sensors to imaging and information technology. To realize such applications, synthesis of well defined metal nanoparticles and precise control over assembly are critical. In this paper, we report a synthetic scheme of silver nanoparticles and their combination with dielectrics and/or gain media and their assembly on substrates. Silver nanoparticles are synthesized using a block copolymer of polystyrene and poly(4-vinyl pyridine) (PS-b-P4VP). Well defined nanoparticles were assembled on substrates using a graphoepitaxial approach with topographic patterns prepared by E-beam lithography. The effect of shapes and scales of topographic patterns on the nanoparticle assembly was investigated. Careful optical characterization and potential applications will be discussed.

  8. Block copolymer mediated stabilization of sub-5 nm superparamagnetic nickel nanoparticles in an aqueous medium

    NASA Astrophysics Data System (ADS)

    Bala, Tanushree; Gunning, Robert Denis; Venkatesan, Munuswamy; Godsell, Jeffrey F.; Roy, Saibal; Ryan, Kevin M.

    2009-10-01

    This paper presents a facile method for decreasing the size of water dispersible Ni nanoparticles from 30 to 3 nm by the incorporation of a passivating surfactant combination of pluronic triblock copolymer and oleic acid into a wet chemical reduction synthesis. A detailed study revealed that the size of the Ni nanoparticles is not only critically governed by the concentration of the triblock copolymers but also dependent on the hydrophobic nature of the micelle core formed. The synthesized Ni nanoparticles were thoroughly characterized by means of transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and temperature and field dependent magnetic measurements, along with a comprehensive Fourier transform infrared spectroscopy analysis, in order to predict a possible mechanism of formation.

  9. Phase Transitions and Spatial Organization in Nanoparticle-Block Copolymer Mixtures

    NASA Astrophysics Data System (ADS)

    Kim, Jaeup

    2005-03-01

    Introducing nanoparticles into nanostructured block copolymer phases can dramatically influence the polymer host. Computer simulations [Balazs et al., PRL, 89, 155503 (2002)] suggest inclusions can actually trigger transitions from one polymer phase to another. Simultaneously, the nanoparticles can be organized into complex superstructures, giving composite materials with novel mechanical, electrical and optical properties. Potential applications include catalysts, selective membranes and optical filters. We have developed a first principles theory predicting polymer phases and nanoparticle distributions. We find modification by nanoinclusions of the free energy of stretched polymer domains in lamellar, cylindrical or spherical geometries triggers structural changes and determines particle distributions. Our framework builds on Semenov's description of AB copolymers in the strongly stretched limit by incorporating nanoinclusions. Energy favors segregation into particle-rich regions, while entropy favors particle mixing into the energetically preferred block, say A. When entropy wins (small particles), an A-core cylindrical-to-lamellar phase transition is induced. Interestingly, large particles by contrast microphase separate into copolymer domains (analogous to Semenov's conclusions for homopolymer-copolymer mixtures) triggering reverse phase transitions (e.g. lamellar to A-core cylindrical). We present our results as a complete phase diagram.

  10. “Smart” Diblock Copolymers as Templates for Magnetic-Core Gold-Shell Nanoparticle Synthesis

    SciTech Connect

    Nash, Michael A.; Lai, James J.; Hoffman, Allan S.; Yager, Paul; Stayton, Partick S.

    2010-01-13

    We report a new strategy for synthesizing temperature-responsive γ-Fe2O3-core/Au-shell nanoparticles (Au-mNPs) from diblock copolymer micelles. The amphiphilic diblock copolymer chains were synthesized using reversible addition-fragmentation chain-transfer (RAFT) with a thermally responsive “smart” poly(N-isopropylacrylamide) (pNIPAAm) block and an amine-containing poly(N,N-dimethylaminoethylacrylamide) (DMAEAm) block that acted as a reducing agent during gold shell formation. The Au-mNPs reversibly aggregated upon heating the solution above the transition temperature of pNIPAAm, resulting in a red-shifted localized surface plasmon resonance.

  11. Nanoparticle Formation from Hybrid, Multiblock Copolymers of Poly(Acrylic Acid) and VPGVG Peptide

    PubMed Central

    Grieshaber, Sarah E.; Paik, Bradford A.; Bai, Shi; Kiick, Kristi L.; Jia, Xinqiao

    2012-01-01

    Elastin-mimetic hybrid copolymers with an alternating molecular architecture were synthesized via the step growth polymerization of azide-functionalized, telechelic poly(tert-butyl acrylate) (PtBA) and an alkyne-terminated, valine and glycine-rich peptide with a sequence of (VPGVG)2 (VG2). The resultant hybrid copolymer, [PtBA-VG2]n, contains up to six constituent building blocks and has a polydispersity index (PDI) of ~1.9. Trifluoroacetic acid (TFA) treatment of [PtBA-VG2]n gave rise to an alternating copolymer of poly(acrylic acid) (PAA) and VG2 ([PAA-VG2]n). The modular design permits facile adjustment of the copolymer composition by varying the molecular weight of PAA (22 and 63 repeat units). Characterization by dynamic light scattering indicated that the multiblock copolymers formed discrete nanoparticles at room temperature in aqueous solution at pH 3.8, with an average diameter of 250-270 nm and a particle size distribution of 0.34 for multiblock copolymers containing PAA22 and 0.17 for those containing PAA63. Upon increasing the pH to 7.4, both types of particles were able to swell without being disintegrated, reaching an average diameter of 285-300 nm for [PAA22-VG2]n and 330-350 nm for [PAA63-VG2]n, respectively. The nanoparticles were not dissociated upon the addition of urea, further confirming their unusual stability. The nanoparticles were capable of sequestering a hydrophobic fluorescent dye (pyrene), and the critical aggregation concentration (CAC) was determined to be 1.09 × 10-2 or 1.05 × 10-2 mg/mL for [PAA22-VG2]n and [PAA63-VG2]n, respectively. We suggest that the multiblock copolymers form through collective H-bonding and hydrophobic interactions between the PAA and VG2 peptide units, and that the unusual stability of the multiblock nanoparticles is conferred by the multiblock architecture. These hybrid multiblock copolymers are potentially useful as pH-responsive drug delivery vehicles, with the possibility of drug loading through

  12. Nanoparticles of Poly(Lactide-Co-Glycolide)-d-a-Tocopheryl Polyethylene Glycol 1000 Succinate Random Copolymer for Cancer Treatment

    NASA Astrophysics Data System (ADS)

    Ma, Yuandong; Zheng, Yi; Liu, Kexin; Tian, Ge; Tian, Yan; Xu, Lei; Yan, Fei; Huang, Laiqiang; Mei, Lin

    2010-07-01

    Cancer is the leading cause of death worldwide. Nanomaterials and nanotechnologies could provide potential solutions. In this research, a novel biodegradable poly(lactide-co-glycolide)-d-a-tocopheryl polyethylene glycol 1000 succinate (PLGA-TPGS) random copolymer was synthesized from lactide, glycolide and d-a-tocopheryl polyethylene glycol 1000 succinate (TPGS) by ring-opening polymerization using stannous octoate as catalyst. The obtained random copolymers were characterized by 1H NMR, FTIR, GPC and TGA. The docetaxel-loaded nanoparticles made of PLGA-TPGS copolymer were prepared by a modified solvent extraction/evaporation method. The nanoparticles were then characterized by various state-of-the-art techniques. The results revealed that the size of PLGA-TPGS nanoparticles was around 250 nm. The docetaxel-loaded PLGA-TPGS nanoparticles could achieve much faster drug release in comparison with PLGA nanoparticles. In vitro cellular uptakes of such nanoparticles were investigated by CLSM, demonstrating the fluorescence PLGA-TPGS nanoparticles could be internalized by human cervix carcinoma cells (HeLa). The results also indicated that PLGA-TPGS-based nanoparticles were biocompatible, and the docetaxel-loaded PLGA-TPGS nanoparticles had significant cytotoxicity against Hela cells. The cytotoxicity against HeLa cells for PLGA-TPGS nanoparticles was in time- and concentration-dependent manner. In conclusion, PLGA-TPGS random copolymer could be acted as a novel and promising biocompatible polymeric matrix material applicable to nanoparticle-based drug delivery system for cancer chemotherapy.

  13. Hyaluronic acid grafted PLGA copolymer nanoparticles enhance the targeted delivery of Bromelain in Ehrlich's Ascites Carcinoma.

    PubMed

    Bhatnagar, Priyanka; Pant, Aditya Bhushan; Shukla, Yogeshwer; Panda, Amulya; Gupta, Kailash Chand

    2016-08-01

    Rapidly increasing malignant neoplastic disease demands immediate attention. Several dietary compounds have recently emerged as strong anti-cancerous agents. Among, Bromelain (BL), a protease from pineapple plant, was used to enhance its anti-cancerous efficacy using nanotechnology. In lieu of this, hyaluronic acid (HA) grafted PLGA copolymer, having tumor targeting ability, was developed. BL was encapsulated in copolymer to obtain BL-copolymer nanoparticles (NPs) that ranged between 140 to 281nm in size. NPs exhibited higher cellular uptake and cytotoxicity in cells with high CD44 expression as compared with non-targeted NPs. In vivo results on tumor bearing mice showed that NPs were efficient in suppressing the tumor growth. Hence, the formulation could be used as a self-targeting drug delivery cargo for the remission of cancer. PMID:27287553

  14. Mesostructured Block Copolymer Nanoparticles: Versatile Templates for Hybrid Inorganic/Organic Nanostructures

    PubMed Central

    Connal, Luke A.; Lynd, Nathaniel A.; Robb, Maxwell J.; See, Kimberly A.; Jang, Se Gyu; Spruell, Jason M.

    2012-01-01

    We present a versatile strategy to prepare a range of nanostructured poly(styrene)-block-poly(2-vinyl pyridine) copolymer particles with tunable interior morphology and controlled size by a simple solvent exchange procedure. A key feature of this strategy is the use of functional block copolymers incorporating reactive pyridyl moieties which allow the absorption of metal salts and other inorganic precursors to be directed. Upon reduction of the metal salts, well-defined hybrid metal nanoparticle arrays could be prepared, while the use of oxide precursors followed by calcination permits the synthesis of silica and titania particles. In both cases, ordered morphologies templated by the original block copolymer domains were obtained. PMID:23335837

  15. Preparation and in vitro evaluation of doxorubicin-loaded Fe3O4 magnetic nanoparticles modified with biocompatible copolymers

    PubMed Central

    Akbarzadeh, Abolfazl; Mikaeili, Haleh; Zarghami, Nosratollah; Mohammad, Rahmati; Barkhordari, Amin; Davaran, Soodabeh

    2012-01-01

    Background Superparamagnetic iron oxide nanoparticles are attractive materials that have been widely used in medicine for drug delivery, diagnostic imaging, and therapeutic applications. In our study, superparamagnetic iron oxide nanoparticles and the anticancer drug, doxorubicin hydrochloride, were encapsulated into poly (D, L-lactic-co-glycolic acid) poly (ethylene glycol) (PLGA-PEG) nanoparticles for local treatment. The magnetic properties conferred by superparamagnetic iron oxide nanoparticles could help to maintain the nanoparticles in the joint with an external magnet. Methods A series of PLGA:PEG triblock copolymers were synthesized by ring-opening polymerization of D, L-lactide and glycolide with different molecular weights of polyethylene glycol (PEG2000, PEG3000, and PEG4000) as an initiator. The bulk properties of these copolymers were characterized using 1H nuclear magnetic resonance spectroscopy, gel permeation chromatography, Fourier transform infrared spectroscopy, and differential scanning calorimetry. In addition, the resulting particles were characterized by x-ray powder diffraction, scanning electron microscopy, and vibrating sample magnetometry. Results The doxorubicin encapsulation amount was reduced for PLGA:PEG2000 and PLGA:PEG3000 triblock copolymers, but increased to a great extent for PLGA:PEG4000 triblock copolymer. This is due to the increased water uptake capacity of the blended triblock copolymer, which encapsulated more doxorubicin molecules into a swollen copolymer matrix. The drug encapsulation efficiency achieved for Fe3O4 magnetic nanoparticles modified with PLGA:PEG2000, PLGA:PEG3000, and PLGA:PEG4000 copolymers was 69.5%, 73%, and 78%, respectively, and the release kinetics were controlled. The in vitro cytotoxicity test showed that the Fe3O4-PLGA:PEG4000 magnetic nanoparticles had no cytotoxicity and were biocompatible. Conclusion There is potential for use of these nanoparticles for biomedical application. Future work

  16. Fabrication of platinum nanoparticles in aqueous solution and solid phase using amphiphilic PB-b-PEO copolymer nanoreactors

    SciTech Connect

    Hoda, Numan; Budama, Leyla; Çakır, Burçin Acar; Topel, Önder; Ozisik, Rahmi

    2013-09-01

    Graphical abstract: TEM image of Pt nanoparticles produced by reducing by NaBH{sub 4} within PB-b-PEO micelles in aqueous media (scale bar 1 nm). - Highlights: • Pt nanoparticles were synthesized within amphiphilic diblock copolymer micelles. • The effects of reducing agents and precursor dose on Pt np size were investigated. • The effect on fabrication of Pt np by reducing in aqueous and solid phases was compared. • The size of nanoparticles was about 1.4 nm for all doses and reducing agents types. - Abstract: Fabrication of Pt nanoparticles using an amphiphilic copolymer template in aqueous solution was achieved via polybutadiene-block-polyethyleneoxide copolymer micelles, which acted as nanoreactors. In addition, Pt nanoparticles were synthesized using hydrogen gas as the reducing agent in solid state for the first time to compare against solution synthesis. The influences of loaded precursor salt amount to micelles and the type of reducing agent on the size of nanoparticles were investigated through transmission electron microscopy. It was found that increasing the ratio of precursor salt to copolymer and using different type of reducing agent, even in solid phase reduction, did not affect the nanoparticle size. The average size of Pt nanoparticles was estimated to be 1.4 ± 0.1 nm. The reason for getting same sized nanoparticles was discussed in the light of nucleation, growth process, stabilization and diffusion of nanoparticles within micelles.

  17. Sulfate-based anionic diblock copolymer nanoparticles for efficient occlusion within zinc oxide

    NASA Astrophysics Data System (ADS)

    Ning, Y.; Fielding, L. A.; Andrews, T. S.; Growney, D. J.; Armes, S. P.

    2015-04-01

    Occlusion of copolymer particles within inorganic crystalline hosts not only provides a model for understanding the crystallisation process, but also may offer a direct route for the preparation of novel nanocomposite materials with emergent properties. In the present paper, a series of new well-defined anionic diblock copolymer nanoparticles are synthesised by polymerisation-induced self-assembly (PISA) via reversible addition-fragmentation chain transfer (RAFT) aqueous emulsion polymerisation and then evaluated as crystal habit modifiers for the in situ formation of ZnO in aqueous solution. Systematic studies indicate that both the chemical nature (i.e. whether sulfate-based or carboxylate-based) and the mean degree of polymerisation (DP) of the anionic stabiliser block play vital roles in determining the crystal morphology. In particular, sulfate-functionalised nanoparticles are efficiently incorporated within the ZnO crystals whereas carboxylate-functionalised nanoparticles are excluded, thus anionic character is a necessary but not sufficient condition for successful occlusion. Moreover, the extent of nanoparticle occlusion within the ZnO phase can be as high as 23% by mass depending on the sulfate-based nanoparticle concentration. The optical properties, chemical composition and crystal structure of the resulting nanocomposite crystals are evaluated and an occlusion mechanism is proposed based on the observed evolution of the ZnO morphology in the presence of sulfate-based anionic nanoparticles. Finally, controlled deposition of a 5 nm gold sol onto porous ZnO particles (produced after calcination of the organic nanoparticles) significantly enhances the rate of photocatalytic decomposition of a model rhodamine B dye on exposure to a relatively weak UV source.Occlusion of copolymer particles within inorganic crystalline hosts not only provides a model for understanding the crystallisation process, but also may offer a direct route for the preparation of novel

  18. Aqueous Solution Behavior and Metal Nanoparticle Formation in pH-responsive Amphiphilic Diblock Copolymers

    NASA Astrophysics Data System (ADS)

    Anastasiadis, Spiros H.; Katsamanis, Vasileios; Afchoudia, Theodora; Vamvakaki, Maria; Sidorov, Stanislav; Kostylev, Maxim; Bronstein, Lyudmila

    2004-03-01

    Dynamic light scattering, pH-metry, 1H-NMR, transmission electron microscopy, and atomic force microscopy have been used to investigate the micellar behavior and metal-nanoparticle formation in poly(2-diethylamino ethylmethacrylate)-block-poly(hexa(ethylene glycol) methacrylate), PDEAEMA-b-PHEGMA, amphiphilic block copolymers in aqueous media. The hydrophobic PDEAEMA block of these copolymers is pH-sensitive: at low pH it can be protonated and it becomes partially or completely hydrophilic leading to molecular solubility whereas at higher pH micelles are formed. The micelle formation is studied as a function of the diblock copolymer characteristics. The micelles consist of a PDEAEMA core and a PHEGMA corona, where the core can dissolve metal compounds due to coordination. Moreover, incorporation of metal compounds (even at low pH) results in self-assembling of the block copolymer molecules and formation of micelles. In all these micellar nanoreactors, metal nanoparticles nucleate and grow upon reduction with sizes in the range of a few nanometers as observed by TEM. These particles exhibit significantly enhanced catalytic properties for hydrogenation and oxidation reactions.

  19. Computer Simulation of Drug-Encapsulating Copolymer Nanoparticles for Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Woodhead, Jeffrey Laurence

    2011-12-01

    Copolymer nanoparticles are being investigated as drug delivery agents, and hold great promise for increasing the solubility and improving the targeting of anti-cancer drugs. However, results from encapsulation experiments are inconsistent, and a theoretical framework for understanding drug encapsulation within block copolymer nanoparticles is necessary. Our goal is to provide some understanding of how block copolymer nanoparticles assemble in the presence of drugs and what changes in system variables improve drug encapsulation efficiency. We perform discontinuous molecular dynamics (DMD) computer simulations on a model copolymer/drug/solvent system, where the drug is modeled as a generic solventphobic solute. We investigate the dependence of the structural phase behavior and encapsulation efficiency of the copolymer/solute/solvent system on the system packing fraction, the copolymer volume fraction, the head-solute interaction strength, and the head-head interaction strength. We determine what changes in these variables produce desirable solute encapsulation behavior and what changes in these variables improve the encapsulation efficiency of the system. We find that varying our system variables produces five different structural phases. Three of these phases do not encapsulate solute: the "micelle + dispersed solute" phase, the "micelle + solute cluster" phase, and the "solute + drug cluster" phase. Two of these phases encapsulate solute: the "micelle encapsulating drug aggregate" phase and the "micelles encapsulating dispersed solute" phase. This latter phase is the ideal phase for effective drug encapsulation. We find that the head-solute interaction strength serves as a coupling parameter linking the copolymer and solute systems and thus dictating the encapsulating ability of the system. We investigate the encapsulation efficiency of the system at various values of the packing fraction, polymer volume fraction, and head-head interaction strength. We find that

  20. Preparation and catalytic ability to reduce hydrogen peroxide of Ag nanoparticles highly dispersed via hyperbranched copolymer

    NASA Astrophysics Data System (ADS)

    Yao, Lu; Yang, Weiying; Yang, Jie; He, Linghao; Sun, Jing; Song, Rui; Ma, Zhi; Huang, Wei

    2011-03-01

    Highly dispersed Ag nanoparticles, stabilized by hyperbranched copolymers (HPCs), were prepared by chemical reduction in toluene. These Ag NPs were used further for the fabrication of a hydrogen peroxide (H2O2) sensor, by which a good catalytic ability for the reduction of H2O2 was found.Highly dispersed Ag nanoparticles, stabilized by hyperbranched copolymers (HPCs), were prepared by chemical reduction in toluene. These Ag NPs were used further for the fabrication of a hydrogen peroxide (H2O2) sensor, by which a good catalytic ability for the reduction of H2O2 was found. Electronic supplementary information (ESI) available: Structure and structure parameters of the HPCs, and UV-vis and XPS spectra of the NPs . See DOI: 10.1039/c0nr00567c

  1. Nanomanufacturing of Gold Nanoparticle Arrays Using Peptide-Derivatized Block Copolymer Templates

    NASA Astrophysics Data System (ADS)

    Rao, Tingling; Singh, Gurpreet; Xie, Sibai; Karim, Alamgir; Becker, Matthew

    2013-03-01

    Collective surface plasmons (SPs) displayed by two-dimensional (2-D) Au nanostructures are important for applications such as plasmonics and plasmonic sensing. However, methods for fabricating programmable highly-ordered arrays of Au nanoparticles with nanoscale precision are limited. Here, we report a peptide--derivated block copolymer based rout towards continuous fabrication of Au nanoparticle superlatice with tunable structures. We successfully obtain discrete, hexagonally-packed Au nanoparticle hierarchical structures where Au-to-Au nanoparticle spacing is precisely controlled by the underlying PMMA cylindrical phase of the block copolymer (BCP). Dynamic thermal field processing techniques offer a facile and continuous rout to tune the BCP assembly, thus enabling versatile arrangement of Au nanostructures from Au-dots to Au-lines. Our method may open a cost-effective way towards assembly of 2-D Au nanoparticles with tunable structures by carefully tuning molecular parameters - a promising step to novel nanodevices. Akron Functional Materials Center (AFMC) and The University of Akron Research Foundation

  2. Construction and characterization of hybrid nanoparticles via block copolymer blends and kinetic control of solution assembly

    NASA Astrophysics Data System (ADS)

    Chen, Yingchao

    Amphiphilic block copolymers are able to self-assemble into well-defined nanostructures in aqueous solutions or aqueous/miscible organic solutions. These structures include traditional spheres, cylinders and vesicles, which mimic nanostructures formed by small molecule analogs like lipids and surfactants. The large molecular weight and complex macromolecular architectures provide several advantages over small molecule amphiphiles, including the large chemical versatility, control over the size and shape of the solution assemblies, unique slow chain exchange and exceptional increased versatility in possible nanostructures. These advantages have motivated the noteworthy study of constructing well-defined, controlled and, especially, multicompartment and multigeometry polymeric nanoobjects for potential multiple nanotechnology applications. To reach complexity and well-controlled nanostructures, the facile utility and fundamental understanding of the parameters that influence the effective construction of solution assemblies needs to be continued. Given these motivations, this dissertation demonstrated the design of block copolymers, manipulation of kinetic control parameters of solution assembly, and characterization of hybrid nanostructures with the aim of creating new, well-defined nanostructures. The first objective of this dissertation was to explore the effects of solvent processing rates in influencing multicompartment and multigeometry nanoparticle construction, structure evolution over long-time aging and nanoparticle formation mechanisms. The noticeable effects of water addition rates on the formation of various nanostructures were studied by cryogenic transmission electron microscopy, selective staining and small angle scattering. It was revealed that the water addition rate have significant influence over the final assemblies in block copolymer blends. New shapes of multicompartment and multigeometry nanoparticles have been constructed including hybrid

  3. Role of defects on self-assembly of nanoparticles in block copolymer thin film

    NASA Astrophysics Data System (ADS)

    Kim, Jenny; Green, Peter

    2011-03-01

    The structure of A-b-B block copolymer (BCP) thin films is often exploited as scaffolds for directing nanoparticles into various, long-range ordered geometries. Depending on the affinity between nanoparticles and block chains, nanoparticles preferentially segregate to either A or B domains. We show that dislocations may play a dominant role in the assembly of large nanoparticles in BCP thin film that order at suboptimal thicknesses. Edge dislocations are ubiquitous in lamellar BCP thin films forming a partial surface layer, i.e. holes or island structures. When the ratio of the nanoparticle diameter, d, to the domain dimension, L, d/L 0.15, the nanoparticles were distributed uniformly throughout the film. However for larger values of d/L, the nanoparticles reside primarily at the dislocation cores. In the case of films of initial film thicknesses between L h < 3L the nanoparticles self-assemble into 2-dimensional planar shapes at the boundaries of holes or islands where edge dislocations are located.

  4. Oligothiol Graft-Copolymer Coatings Stabilize Gold Nanoparticles Against Harsh Experimental Conditions

    PubMed Central

    Kang, Jun Sung; Taton, T. Andrew

    2013-01-01

    We report that poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) copolymers that bear multiple thiol groups on the polymer backbone are exceptional ligands for gold nanoparticles (AuNPs). In general, these graft copolymer ligands stabilize AuNPs against environments that would ordinarily lead to particle aggregation. To characterize the effect of copolymer structure on AuNP stability, we synthesized thiolated PLL-g-PEGs (PLL-g-[PEG:SH]) with different backbone lengths, PEG grafting densities, and number of thiols per polymer chain. AuNPs were then combined with these polymer ligands, and the stabilities of the resulting AuNP@PLL-g-[PEG:SH] particles against high temperature, oxidants, and competing thiol ligands were characterized using dynamic light scattering, visible absorption spectroscopy, and fluorescence spectrophotometry. Our observations indicate that thiolated PLL-g-PEG ligands combine thermodynamic stabilization via multiple Au-S bonds and steric stabilization by PEG grafts, and the best graft copolymer ligands balance these two effects. We hope that this new ligand system enables AuNPs to be applied to biotechnological applications that require harsh experimental conditions. PMID:22957513

  5. Sulfate-based anionic diblock copolymer nanoparticles for efficient occlusion within zinc oxide.

    PubMed

    Ning, Y; Fielding, L A; Andrews, T S; Growney, D J; Armes, S P

    2015-04-21

    Occlusion of copolymer particles within inorganic crystalline hosts not only provides a model for understanding the crystallisation process, but also may offer a direct route for the preparation of novel nanocomposite materials with emergent properties. In the present paper, a series of new well-defined anionic diblock copolymer nanoparticles are synthesised by polymerisation-induced self-assembly (PISA) via reversible addition-fragmentation chain transfer (RAFT) aqueous emulsion polymerisation and then evaluated as crystal habit modifiers for the in situ formation of ZnO in aqueous solution. Systematic studies indicate that both the chemical nature (i.e. whether sulfate-based or carboxylate-based) and the mean degree of polymerisation (DP) of the anionic stabiliser block play vital roles in determining the crystal morphology. In particular, sulfate-functionalised nanoparticles are efficiently incorporated within the ZnO crystals whereas carboxylate-functionalised nanoparticles are excluded, thus anionic character is a necessary but not sufficient condition for successful occlusion. Moreover, the extent of nanoparticle occlusion within the ZnO phase can be as high as 23% by mass depending on the sulfate-based nanoparticle concentration. The optical properties, chemical composition and crystal structure of the resulting nanocomposite crystals are evaluated and an occlusion mechanism is proposed based on the observed evolution of the ZnO morphology in the presence of sulfate-based anionic nanoparticles. Finally, controlled deposition of a 5 nm gold sol onto porous ZnO particles (produced after calcination of the organic nanoparticles) significantly enhances the rate of photocatalytic decomposition of a model rhodamine B dye on exposure to a relatively weak UV source. PMID:25799462

  6. Paclitaxel-incorporated nanoparticles using block copolymers composed of poly(ethylene glycol)/poly(3-hydroxyoctanoate).

    PubMed

    Kim, Hyun Yul; Ryu, Je Ho; Chu, Chong Woo; Son, Gyung Mo; Jeong, Young-Il; Kwak, Tae-Won; Kim, Do Hyung; Chung, Chung-Wook; Rhee, Young Ha; Kang, Dae Hwan; Kim, Hyung Wook

    2014-01-01

    Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a (1)H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.) was analyzed with gel permeation chromatography (GPC). Paclitaxel as a model anticancer drug was incorporated into the nanoparticles of PHO/PEG block copolymer. They have spherical shapes and their particle sizes were less than 100 nm. In a (1)H-NMR study in D2O, specific peaks of PEG solely appeared while peaks of PHO disappeared, indicating that nanoparticles have core-shell structures. The higher M.W. of PEG decreased loading efficiency and particle size. The higher drug feeding increased drug contents and average size of nanoparticles. In the drug release study, the higher M.W. of PEG block induced the acceleration of drug release rate. The increase in drug contents induced the slow release rate of drug. In an antitumor activity study in vitro, paclitaxel nanoparticles have practically similar anti-proliferation activity against HCT116 human colon carcinoma cells. In an in vivo animal study using HCT116 colon carcinoma cell-bearing mice, paclitaxel nanoparticles have enhanced antitumor activity compared to paclitaxel itself. Therefore, paclitaxel-incorporated nanoparticles of PHO/PEG block copolymer are a promising vehicle for antitumor drug delivery. PMID:25288916

  7. Paclitaxel-incorporated nanoparticles using block copolymers composed of poly(ethylene glycol)/poly(3-hydroxyoctanoate)

    PubMed Central

    2014-01-01

    Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a 1H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.) was analyzed with gel permeation chromatography (GPC). Paclitaxel as a model anticancer drug was incorporated into the nanoparticles of PHO/PEG block copolymer. They have spherical shapes and their particle sizes were less than 100 nm. In a 1H-NMR study in D2O, specific peaks of PEG solely appeared while peaks of PHO disappeared, indicating that nanoparticles have core-shell structures. The higher M.W. of PEG decreased loading efficiency and particle size. The higher drug feeding increased drug contents and average size of nanoparticles. In the drug release study, the higher M.W. of PEG block induced the acceleration of drug release rate. The increase in drug contents induced the slow release rate of drug. In an antitumor activity study in vitro, paclitaxel nanoparticles have practically similar anti-proliferation activity against HCT116 human colon carcinoma cells. In an in vivo animal study using HCT116 colon carcinoma cell-bearing mice, paclitaxel nanoparticles have enhanced antitumor activity compared to paclitaxel itself. Therefore, paclitaxel-incorporated nanoparticles of PHO/PEG block copolymer are a promising vehicle for antitumor drug delivery. PMID:25288916

  8. Polyaspartamide-Polylactide Graft Copolymers with Tunable Properties for the Realization of Fluorescent Nanoparticles for Imaging.

    PubMed

    Craparo, Emanuela Fabiola; Porsio, Barbara; Mauro, Nicolò; Giammona, Gaetano; Cavallaro, Gennara

    2015-08-01

    Here, the synthesis and the characterization of novel amphiphilic graft copolymers with tunable properties, useful in obtaining polymeric fluorescent nanoparticles for application in imaging, are described. These copolymers are obtained by chemical conjugation of rhodamine B (RhB) moieties, polylactic acid (PLA), and O-(2-aminoethyl)-O'-methyl poly(ethylene glycol) (PEG) on α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA). In particular, PHEA is first functionalized with RhB to obtain PHEA-RhB with a derivatization degree in RhB (DDRhB ) equal to 0.55 mol%. By varying the reaction conditions, different amounts of PLA are grafted on PHEA-RhB to obtain PHEA-RhB-PLA with DDPLA equal to 1.9, 4.0, and 6.2 mol%. Then, PEG chains are grafted on PHEA-RhB-PLA derivatives to obtain PHEA-RhB-PLA-PEG graft copolymers. The preparation of polymeric fluorescent nanoparticles with tunable properties and spherical shape is described by using PHEA-RhB-PLA-PEG with DD in PLA and PEG equal to 4.0 and 4.9 mol%, by following easily scaling up processes, such as emulsion-solvent evaporation and high pressure homogenization (HPH)-solvent evaporation techniques. PMID:26010226

  9. Photo, pH, and thermo triple-responsive spiropyran-based copolymer nanoparticles for controlled release.

    PubMed

    Chen, Shuo; Jiang, Fengjuan; Cao, Ziquan; Wang, Guojie; Dang, Zhi-Min

    2015-08-14

    A spiropyran-based amphiphilic random copolymer was synthesized and self-assembled into photo-, pH-, and thermo-responsive micellar nanoparticles. The triple-stimuli triggered morphological changes of the nanoparticles were revealed by TEM and DLS. Highly efficient controlled release of encapsulated molecules, coumarin 102, from the nanoparticles under stimulation of UV light, acid and the combined stimuli could be realized. PMID:26160558

  10. Functional block copolymer nanoparticles: toward the next generation of delivery vehicles†

    PubMed Central

    Robb, Maxwell J.; Connal, Luke A.; Lee, Bongjae F.; Lynd, Nathaniel A.; Hawker, Craig J.

    2014-01-01

    The self-assembly of functional block copolymers (BCPs) into dispersed nanoparticles is a powerful technique for the preparation of novel delivery vehicles with precise control of morphology and architecture. Well-defined BCPs containing an alkyne-functional, biodegradable polylactide (PLA) block were synthesized and conjugated with azide-functional coumarin dyes via copper catalyzed azide alkyne cycloaddition ‘click’ chemistry. Self-assembled nanoparticles with internal nanophase-separated morphologies could then be accessed by carefully controlling the composition of the BCPs and release of the covalently attached model payload was shown to occur under physiological conditions via the degradation of the PLA scaffold. These results demonstrate the potential of self-assembled nanoparticles as modular delivery vehicles with multiple functionalities, nanostructures, and compartmentalized internal morphology. PMID:25484930

  11. Biocompatible zwitterionic sulfobetaine copolymer-coated mesoporous silica nanoparticles for temperature-responsive drug release.

    PubMed

    Sun, Jiao-Tong; Yu, Zhi-Qiang; Hong, Chun-Yan; Pan, Cai-Yuan

    2012-05-14

    A novel nanocontainer, which could regulate the release of payloads, has been successfully fabricated by attaching zwitterionic sulfobetaine copolymer onto the mesoporous silica nanoparticles (MSNs). RAFT polymerization is employed to prepare the hybrid poly(2-(dimethylamino)ethyl methacrylate)-coated MSNs (MSN-PDMAEMA). Subsequently, the tertiary amine groups in PDMAEMA are quaternized with 1,3-propanesultone to get poly(DMAEMA-co-3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate)-coated MSNs [MSN-Poly(DMAEMA-co-DMAPS)]. The zwitterionic PDMAPS component endows the nanocarrier with biocompatibility, and the PDMAEMA component makes the copolymer shell temperature-responsive. Controlled release of loaded rhodamine B has been achieved in the saline solutions. PMID:22488562

  12. A Comparative Study of Interfacial Slip in Polymer Blends with Nanoparticles and Diblock Copolymer Compatibilizers

    NASA Astrophysics Data System (ADS)

    Ortiz, Joseph; Gersappe, Dilip

    2012-02-01

    The interfacial region in polymer blends has been identified as a low viscosity region in which considerable slip can occur when the blend is subjected to shear forces. Here we use Molecular Dynamics simulations to establish and compare the roles that added nanoparticle fillers and diblock copolymers play in modifying the interfacial rheology. By choosing conditions under which the fillers and diblocks are localized, either in the two phases or at the interface, we can look at the interplay between their strengthening capabilities and the change in the interfacial slip behavior. We examine particle size, attraction between the particle and the polymer component, and the amount of filler in the material and compared this to systems including diblock copolymers at the same volume fraction. Our studies are performed, for a variety of shear values, both above and below the point at which the filler particles form a transient network in the blend.

  13. Controllable Heparin-Based Comb Copolymers and Their Self-assembled Nanoparticles for Gene Delivery.

    PubMed

    Nie, Jing-Jun; Zhao, Weiyi; Hu, Hao; Yu, Bingran; Xu, Fu-Jian

    2016-04-01

    Polysaccharide-based copolymers have attracted much attention due to their effective performances. Heparin, as a kind of polysaccharide with high negative charge densities, has attracted much attention in biomedical fields. In this work, we report a flexible way to adjust the solubility of heparin from water to oil via the introduction of tetrabutylammonium groups for further functionalization. A range of heparin-based comb copolymers with poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMEMA), poly(dimethylaminoethyl methacrylate) (PDMAEMA), or PPEGMEMA-b-PDMAEMA side chains were readily synthesized in a MeOH/dimethylsulfoxide mixture via atom-transfer radical polymerization. The heparin-based polymer nanoparticles involving cationic PDMAEMA were produced due to the electrostatic interaction between the negatively charged heparin backbone and PDMAEMA grafts. Then the pDNA condensation ability, cytotoxicity, and gene transfection efficiency of the nanoparticles were characterized in comparison with the reported gene vectors. The nanoparticles were proved to be effective gene vectors with low cytotoxicity and high transfection efficiency. This study demonstrates that by adjusting the solubility of heparin, polymer graft functionalization of heparin can be readily realized for wider applications. PMID:26947134

  14. Synthesis of magnetic composite nanoparticles enveloped in copolymers specified for scale inhibition application

    NASA Astrophysics Data System (ADS)

    Do, Bao Phuong Huu; Dung Nguyen, Ba; Duy Nguyen, Hoang; Nguyen, Phuong Tung

    2013-12-01

    We report the synthesis of magnetic iron oxide nanoparticles encapsulated in maleic acid-2-acrylamido-2-methyl-1-propanesulfonate based polymer. This composite nanoparticle is specified for the high-pressure/high-temperature (HPHT) oilfield scale inhibition application. The process includes a facile-ultrasound-supported addition reaction to obtain iron oxide nanoparticles with surface coated by oleic acid. Then via inverse microemulsion polymerization with selected monomers, the specifically designed copolymers have been formatted in nanoscale. The structure and morphology of obtained materials were characterized by transmission electron microscopy (TEM), x-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and the thermal stability. The effectiveness of synthesized compounds as a carbonate scale inhibitor was investigated by testing method NACE standard TM 03-074-95 at aging temperature of 70, 90 and 120 °C. The magnetic nanocomposite particles can be easily collected and detected demonstrating their superior monitoring ability, which is absent in the case of conventional copolymer-based scale inhibitor.

  15. Hierarchically Ordered Polymer/Block Copolymer/Nanoparticle Systems Enabled via Holographic Photopolymerization

    NASA Astrophysics Data System (ADS)

    Bunning, Timothy

    2010-03-01

    Combining top-down and bottom-up methods in one process step creates novel hierarchical nanostructures with tailored properties. We demonstrate the ability to spatially pattern block copolymers or nanoparticles into periodic volume gratings using a one-step holographic patterning (HP) technique. The confinement of the second phase (e.g. block copolymer or nanoparticle) within the grating results in local preferential ordering of that phase, enabling single-step fabrication of complex hierarchical structures. As an example, this simple interfering photopolymer `writing' technique was utilized to generate a layer-in-layer structure of poly(ethylene oxide-b-epsilon-caprolactone) confined between crosslinked resin. The period of the volume grating was 200 nm, with the BCP occupying 100 nm of the 1-D structure. The BCP crystallized/phase separated to produce a lamellar structure with a 21 nm periodicity. This system exhibits interesting thermo-optical behavior during heating/cooling cycles. Alternatively, a layered polymer/nanoparticle composite was created through a one-step two-beam interference lithographic exposure of a dispersion of silica nanoparticles within a photopolymerizable mixture at a wavelength of 532 nm. The effects of exposure time and power, nanoparticle size, and periodicity on the nanocomposite structure were measured with transmission electron microscopy. The optical properties of the formed gratings were probed in real-time during formation. Collaborators on this work include M. Birnkrant and C. Li from Drexel University, A. Juhl and P. Braun from UIUC, and L. Natarajan, V. Tondiglia, and R. Vaia from AFRL.

  16. Paclitaxel-loaded nanoparticles of star-shaped cholic acid-core PLA-TPGS copolymer for breast cancer treatment

    NASA Astrophysics Data System (ADS)

    Tang, Xiaolong; Cai, Shuyu; Zhang, Rongbo; Liu, Peng; Chen, Hongbo; Zheng, Yi; Sun, Leilei

    2013-10-01

    A system of novel nanoparticles of star-shaped cholic acid-core polylactide- d-α-tocopheryl polyethylene glycol 1000 succinate (CA-PLA-TPGS) block copolymer was developed for paclitaxel delivery for breast cancer treatment, which demonstrated superior in vitro and in vivo performance in comparison with paclitaxel-loaded poly( d, l-lactide- co-glycolide) (PLGA) nanoparticles and linear PLA-TPGS nanoparticles. The paclitaxel- or couramin 6-loaded nanoparticles were fabricated by a modified nanoprecipitation method and then characterized in terms of size, surface charge, surface morphology, drug encapsulation efficiency, and in vitro drug release. The CA-PLA-TPGS nanoparticles were found to be spherical in shape with an average size of around 120 nm. The nanoparticles were found to be stable, showing no change in the particle size and surface charge during 90-day storage of the aqueous solution. The release profiles of the paclitaxel-loaded nanoparticles exhibited typically biphasic release patterns. The results also showed that the CA-PLA-TPGS nanoparticles have higher antitumor efficacy than the PLA-TPGS nanoparticles and PLGA nanoparticles in vitro and in vivo. In conclusion, such nanoparticles of star-shaped cholic acid-core PLA-TPGS block copolymer could be considered as a potentially promising and effective strategy for breast cancer treatment.

  17. Microspheres Assembled from Chitosan-Graft-Poly(lactic acid) Micelle-Like Core-Shell Nanospheres for Distinctly Controlled Release of Hydrophobic and Hydrophilic Biomolecules.

    PubMed

    Niu, Xufeng; Liu, Zhongning; Hu, Jiang; Rambhia, Kunal J; Fan, Yubo; Ma, Peter X

    2016-07-01

    To simultaneously control inflammation and facilitate dentin regeneration, a copolymeric micelle-in-microsphere platform is developed in this study, aiming to simultaneously release a hydrophobic drug to suppress inflammation and a hydrophilic biomolecule to enhance odontogenic differentiation of dental pulp stem cells in a distinctly controlled fashion. A series of chitosan-graft-poly(lactic acid) copolymers is synthesized with varying lactic acid and chitosan weight ratios, self-assembled into nanoscale micelle-like core-shell structures in an aqueous system, and subsequently crosslinked into microspheres through electrostatic interaction with sodium tripolyphosphate. A hydrophobic biomolecule either coumarin-6 or fluocinolone acetonide (FA) is encapsulated into the hydrophobic cores of the micelles, while a hydrophilic biomolecule either bovine serum albumin or bone morphogenetic protein 2 (BMP-2) is entrapped in the hydrophilic shells and the interspaces among the micelles. Both hydrophobic and hydrophilic biomolecules are delivered with distinct and tunable release patterns. Delivery of FA and BMP-2 simultaneously suppresses inflammation and enhances odontogenesis, resulting in significantly enhanced mineralized tissue regeneration. This result also demonstrates the potential for this novel delivery system to deliver multiple therapeutics and to achieve synergistic effects. PMID:26987445

  18. Semiconductor nanoparticles in poly((2-dimethylamino)ethyl methacrylate-co-acrylic acid) co-polymers

    NASA Astrophysics Data System (ADS)

    Trandafilović, L. V.; Bibić, N.; Georges, M. K.; Blanuša, J.; Radhakrishnan, T.; Djoković, V.

    2013-11-01

    Nanostructured cadmium selenide (CdSe) and lead sulfide (PbS) semiconductors were prepared in a poly(2-(dimethylamino)ethyl methacrylate-co-acrylic acid) matrix. The obtained nanoparticles were characterized by using optical and structural methods. Co-polymers were synthesized in two different molar ratios of pDMAEMA:acrylic acid monomer units (1:2, 1:1). Transmission electron microscopy analysis confirmed the presence of nano-sized CdSe and PbS particles. In the case of CdSe, a shift of the onset of the optical absorption toward lower wavelengths was observed. X-ray diffraction analysis revealed that both CdSe and PbS nanoparticles have cubic crystal structure.

  19. Nanoparticle-Induced Ellipse-to-Vesicle Morphology Transition of Rod-Coil-Rod Triblock Copolymer Aggregates.

    PubMed

    Yang, Chaoying; Li, Qing; Cai, Chunhua; Lin, Jiaping

    2016-07-12

    Cooperative self-assembly behavior of rod-coil-rod poly(γ-benzyl-l-glutamate)-block-poly(ethylene glycol)-block-poly(γ-benzyl-l-glutamate) (PBLG-b-PEG-b-PBLG) amphiphilic triblock copolymers and hydrophobic gold nanoparticles (AuNPs) was investigated by both experiments and dissipative particle dynamics (DPD) simulations. It was discovered that pure PBLG-b-PEG-b-PBLG copolymers self-assemble into ellipse-like aggregates, and the morphology transforms into vesicles as AuNPs are introduced. When the hydrophobicity of AuNPs is close to that of the copolymers, AuNPs are homogeneously distributed in the vesicle wall. While for the AuNPs with higher hydrophobicity, they are embedded in the vesicle wall as clusters. In addition to the experimental observations, DPD simulations were performed on the self-assembly behavior of triblock copolymer/nanoparticle mixtures. Simulations well reproduced the morphology transition observed in the experiments and provided additional information such as chain packing mode in aggregates. It is deduced that the main reason for the ellipse-to-vesicle transition of the aggregates is attributed to the breakage of ordered and dense packing of PBLG rods in the aggregate core by encapsulating AuNPs. This study deepens our understanding of the self-assembly behavior of rod-coil copolymer/nanoparticle mixtures and provides strategy for designing hybrid polypeptide nanostructures. PMID:27314970

  20. How Do Spherical Diblock Copolymer Nanoparticles Grow during RAFT Alcoholic Dispersion Polymerization?

    PubMed Central

    2015-01-01

    A poly(2-(dimethylamino)ethyl methacrylate) (PDMA) chain transfer agent (CTA) is used for the reversible addition–fragmentation chain transfer (RAFT) alcoholic dispersion polymerization of benzyl methacrylate (BzMA) in ethanol at 70 °C. THF GPC analysis indicated a well-controlled polymerization with molecular weight increasing linearly with conversion. GPC traces also showed high blocking efficiency with no homopolymer contamination apparent and Mw/Mn values below 1.35 in all cases. 1H NMR studies confirmed greater than 98% BzMA conversion for a target PBzMA degree of polymerization (DP) of up to 600. The PBzMA block becomes insoluble as it grows, leading to the in situ formation of sterically stabilized diblock copolymer nanoparticles via polymerization-induced self-assembly (PISA). Fixing the mean DP of the PDMA stabilizer block at 94 units and systematically varying the DP of the PBzMA block enabled a series of spherical nanoparticles of tunable diameter to be obtained. These nanoparticles were characterized by TEM, DLS, MALLS, and SAXS, with mean diameters ranging from 35 to 100 nm. The latter technique was particularly informative: data fits to a spherical micelle model enabled calculation of the core diameter, surface area occupied per copolymer chain, and the mean aggregation number (Nagg). The scaling exponent derived from a double-logarithmic plot of core diameter vs PBzMA DP suggests that the conformation of the PBzMA chains is intermediate between the collapsed and fully extended state. This is in good agreement with 1H NMR studies, which suggest that only 5−13% of the BzMA residues of the core-forming chains are solvated. The Nagg values calculated from SAXS and MALLS are in good agreement and scale approximately linearly with PBzMA DP. This suggests that spherical micelles grow in size not only as a result of the increase in copolymer molecular weight during the PISA synthesis but also by exchange of individual copolymer chains between micelles

  1. Effect of monomer sequences on conformations of copolymers grafted on spherical nanoparticles: A Monte Carlo simulation study

    SciTech Connect

    Seifpour, Arezou; Spicer, Philip; Nair, Nitish; Jayaraman, Arthi

    2010-04-28

    Functionalizing nanoparticles with organic ligands, such as oligomers, polymers, DNA, and proteins, is an attractive way to manipulate the interfacial interactions between the nanoparticles and the medium the particles are placed in, and thus control the nanoparticle assembly. In this paper we have conducted a Monte Carlo simulation study on copolymer grafted spherical nanoparticles to show the tremendous potential of using monomer sequence on the copolymers to tune the grafted chain conformation, and thus the effective interactions between copolymer grafted nanoparticles. We have studied AB copolymers with alternating, multiblock, or diblock sequences, where either A monomers or B monomers have monomer-monomer attractive interactions. Our focus has been to show the nontrivial effect of monomer sequence on the conformations of the grafted copolymers at various particle diameters, grafting densities, copolymer chain lengths, and monomer-monomer interactions in an implicit small molecule solvent. We observe that the monomer sequence, particle diameter, and grafting density dictate whether (a) the grafted chains aggregate to bring attractive monomers from multiple grafted chains together (interchain and intrachain monomer aggregation) if the enthalpy gained by doing so offsets the entropic loss caused by stretching of chains, or (b) each grafted chain folds onto itself to bring its attractive monomers together (only intrachain monomer aggregation) if the entropic loss from interchain aggregation cannot be overcome by the enthalpic gain. For six copolymers of chain length N=24 grafted on a spherical particle of diameter D=4, interchain and intrachain monomer aggregation occurs, and the radius of gyration varies nonmonotonically with increasing blockiness of the monomer sequence. At larger particle diameters the grafted chains transition to purely intrachain monomer aggregation. The radius of gyration varies monotonically with monomer sequence for intrachain monomer

  2. Biodegradable nanoparticles of amphiphilic triblock copolymers based on poly(3-hydroxybutyrate) and poly(ethylene glycol) as drug carriers.

    PubMed

    Chen, Cheng; Yu, Chung Him; Cheng, Yin Chung; Yu, Peter H F; Cheung, Man Ken

    2006-09-01

    New amorphous amphiphilic triblock copolymers of poly(3-hydroxybutyrate)-poly(ethylene glycol)-poly(3-hydroxybutyrate) (PHB-PEG-PHB) were synthesized using the ring-opening copolymerization of beta-butyrolactone monomer. They were characterized by fluorescence, SEM and (1)H NMR. These triblock copolymers can form biodegradable nanoparticles with core-shell structure in aqueous solution. Comparing to the poly(ethylene oxide)-PHB-poly(ethylene oxide) (PEO-PHB-PEO) copolymers, these nanoparticles exhibited much smaller critical micelle concentrations and better drug loading properties, which indicated that the nanoparticles were very suitable for delivery carriers of hydrophobic drugs. The drug release profile monitored by fluorescence showed that the release of pyrene from the PHB-PEG-PHB nanoparticles exhibited the second-order exponential decay behavior. The initial biodegradation rate of the PHB-PEG-PHB nanoparticles was related to the enzyme amount, the initial concentrations of nanoparticle dispersions and the PHB block length. The biodegraded products detected by (1)H NMR contained 3HB monomer, dimer and minor trimer, which were safe to the body. PMID:16740306

  3. An amphiphilic graft copolymer-based nanoparticle platform for reduction-responsive anticancer and antimalarial drug delivery

    NASA Astrophysics Data System (ADS)

    Najer, Adrian; Wu, Dalin; Nussbaumer, Martin G.; Schwertz, Geoffrey; Schwab, Anatol; Witschel, Matthias C.; Schäfer, Anja; Diederich, François; Rottmann, Matthias; Palivan, Cornelia G.; Beck, Hans-Peter; Meier, Wolfgang

    2016-08-01

    Medical applications of anticancer and antimalarial drugs often suffer from low aqueous solubility, high systemic toxicity, and metabolic instability. Smart nanocarrier-based drug delivery systems provide means of solving these problems at once. Herein, we present such a smart nanoparticle platform based on self-assembled, reduction-responsive amphiphilic graft copolymers, which were successfully synthesized through thiol-disulfide exchange reaction between thiolated hydrophilic block and pyridyl disulfide functionalized hydrophobic block. These amphiphilic graft copolymers self-assembled into nanoparticles with mean diameters of about 30-50 nm and readily incorporated hydrophobic guest molecules. Fluorescence correlation spectroscopy (FCS) was used to study nanoparticle stability and triggered release of a model compound in detail. Long-term colloidal stability and model compound retention within the nanoparticles was found when analyzed in cell media at body temperature. In contrast, rapid, complete reduction-triggered disassembly and model compound release was achieved within a physiological reducing environment. The synthesized copolymers revealed no intrinsic cellular toxicity up to 1 mg mL-1. Drug-loaded reduction-sensitive nanoparticles delivered a hydrophobic model anticancer drug (doxorubicin, DOX) to cancer cells (HeLa cells) and an experimental, metabolically unstable antimalarial drug (the serine hydroxymethyltransferase (SHMT) inhibitor (+/-)-1) to Plasmodium falciparum-infected red blood cells (iRBCs), with higher efficacy compared to similar, non-sensitive drug-loaded nanoparticles. These responsive copolymer-based nanoparticles represent a promising candidate as smart nanocarrier platform for various drugs to be applied to different diseases, due to the biocompatibility and biodegradability of the hydrophobic block, and the protein-repellent hydrophilic block.Medical applications of anticancer and antimalarial drugs often suffer from low aqueous

  4. Amphiphilic copolymer coated upconversion nanoparticles for near-infrared light-triggered dual anticancer treatment

    NASA Astrophysics Data System (ADS)

    Yang, Shun; Li, Najun; Liu, Zhuang; Sha, Wenwei; Chen, Dongyun; Xu, Qingfeng; Lu, Jianmei

    2014-11-01

    The light-triggered controlled release of anticancer drugs accompanied with NIR-responsive photodynamic therapy was prepared via a self-assembly process. Firstly, Mn2+-doped upconversion nanoparticles (UCNPs) were coated with a mesoporous silica shell and modified with photosensitizer (Chlorin e6) and long alkyl chains. And then the NIR light-responsive amphiphilic copolymer containing 9,10-dialkoxyanthracene groups was synthesized and then coated as the outermost layer. Upon irradiation with a 980 nm laser, the CCUCNPs@PM would absorb and then convert the NIR light to higher-energy visible red light (660 nm) via the UCNPs-based core, which could excite Chlorin e6 (Ce-6) to produce singlet oxygen (1O2). Then the 1O2-sensitive dialkoxyanthracene group in the amphiphilic copolymer would be degraded and detach from the surface of the CCUCNPs@PM, followed by the controlled release of the pre-loaded drugs and the photodynamic therapy for cancer cells caused by the excess 1O2. In vitro and in vivo experiments also demonstrated that the drug-loaded CCUCNPs@PM possessed better therapeutic efficacy compared with vacant ones. Therefore, the NIR light-controlled chemotherapy and photodynamic therapy could be realized simultaneously by CCUCNPs@PM.The light-triggered controlled release of anticancer drugs accompanied with NIR-responsive photodynamic therapy was prepared via a self-assembly process. Firstly, Mn2+-doped upconversion nanoparticles (UCNPs) were coated with a mesoporous silica shell and modified with photosensitizer (Chlorin e6) and long alkyl chains. And then the NIR light-responsive amphiphilic copolymer containing 9,10-dialkoxyanthracene groups was synthesized and then coated as the outermost layer. Upon irradiation with a 980 nm laser, the CCUCNPs@PM would absorb and then convert the NIR light to higher-energy visible red light (660 nm) via the UCNPs-based core, which could excite Chlorin e6 (Ce-6) to produce singlet oxygen (1O2). Then the 1O2-sensitive

  5. Combination chemotherapy using core-shell nanoparticles through the self-assembly of HPMA-based copolymers and degradable polyester.

    PubMed

    Jäger, Eliézer; Jäger, Alessandro; Chytil, Petr; Etrych, Tomáš; Ríhová, Blanka; Giacomelli, Fernando Carlos; Stěpánek, Petr; Ulbrich, Karel

    2013-01-28

    The preparation of core-shell polymeric nanoparticles simultaneously loaded with docetaxel (DTXL) and doxorubicin (DOX) is reported herein. The self-assembly of the aliphatic biodegradable copolyester PBS/PBDL (poly(butylene succinate-co-butylene dilinoleate)) and HPMA-based copolymers (N-(2-hydroxypropyl)methacrylamide-based copolymers) hydrophobically modified by the incorporation of cholesterol led to the formation of narrow-size-distributed (PDI<0.10) sub-200-nm polymeric nanoparticles suitable for passive tumor-targeting drug delivery based on the size-dependent EPR (enhanced permeability and retention) effect. The PHPMA provided to the self-assembled nanoparticle stability against aggregation as evaluated in vitro. The highly hydrophobic drug docetaxel (DTXL) was physically entrapped within the PBS/PBDL copolyester core and the hydrophilic drug doxorubicin hydrochloride (DOX·HCl) was chemically conjugated to the reactive PHPMA copolymer shell via hydrazone bonding that allowed its pH-sensitive release. This strategy enabled the combination chemotherapy by the simultaneous DOX and DTXL drug delivery. The structure of the nanoparticles was characterized in detail using static (SLS), dynamic (DLS) and electrophoretic (ELS) light scattering besides transmission electron microscopy (TEM). The use of nanoparticles simultaneously loaded with DTXL and DOX provided a more efficient suppression of tumor-cell growth in mice bearing EL-4 T cell lymphoma when compared to the effect of nanoparticles loaded with either DTXL or DOX separately. Additionally, the obtained self-assembled nanoparticles enable further development of targeting strategies based on the use of multiple ligands attached to an HPMA copolymer on the particle surface for simultaneous passive and active targeting and different combination therapies. PMID:23178950

  6. An amphiphilic graft copolymer-based nanoparticle platform for reduction-responsive anticancer and antimalarial drug delivery.

    PubMed

    Najer, Adrian; Wu, Dalin; Nussbaumer, Martin G; Schwertz, Geoffrey; Schwab, Anatol; Witschel, Matthias C; Schäfer, Anja; Diederich, François; Rottmann, Matthias; Palivan, Cornelia G; Beck, Hans-Peter; Meier, Wolfgang

    2016-08-21

    Medical applications of anticancer and antimalarial drugs often suffer from low aqueous solubility, high systemic toxicity, and metabolic instability. Smart nanocarrier-based drug delivery systems provide means of solving these problems at once. Herein, we present such a smart nanoparticle platform based on self-assembled, reduction-responsive amphiphilic graft copolymers, which were successfully synthesized through thiol-disulfide exchange reaction between thiolated hydrophilic block and pyridyl disulfide functionalized hydrophobic block. These amphiphilic graft copolymers self-assembled into nanoparticles with mean diameters of about 30-50 nm and readily incorporated hydrophobic guest molecules. Fluorescence correlation spectroscopy (FCS) was used to study nanoparticle stability and triggered release of a model compound in detail. Long-term colloidal stability and model compound retention within the nanoparticles was found when analyzed in cell media at body temperature. In contrast, rapid, complete reduction-triggered disassembly and model compound release was achieved within a physiological reducing environment. The synthesized copolymers revealed no intrinsic cellular toxicity up to 1 mg mL(-1). Drug-loaded reduction-sensitive nanoparticles delivered a hydrophobic model anticancer drug (doxorubicin, DOX) to cancer cells (HeLa cells) and an experimental, metabolically unstable antimalarial drug (the serine hydroxymethyltransferase (SHMT) inhibitor (±)-1) to Plasmodium falciparum-infected red blood cells (iRBCs), with higher efficacy compared to similar, non-sensitive drug-loaded nanoparticles. These responsive copolymer-based nanoparticles represent a promising candidate as smart nanocarrier platform for various drugs to be applied to different diseases, due to the biocompatibility and biodegradability of the hydrophobic block, and the protein-repellent hydrophilic block. PMID:27452350

  7. Growth of ordered silver nanoparticles in silica film mesostructured with a triblock copolymer PEO-PPO-PEO

    SciTech Connect

    Bois, L.; Chassagneux, F.; Parola, S.; Bessueille, F.; Battie, Y.; Destouches, N.; Boukenter, A.; Moncoffre, N.

    2009-07-15

    Elaboration of mesostructured silica films with a triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide, (PEO-PPO-PEO) and controlled growth of silver nanoparticles in the mesostructure are described. The films are characterized using UV-visible optical absorption spectroscopy, TEM, AFM, SEM, X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Organized arrays of spherical silver nanoparticles with diameter between 5 and 8 nm have been obtained by NaBH{sub 4} reduction. The size and the repartition of silver nanoparticles are controlled by the film mesostructure. The localization of silver nanoparticles exclusively in the upper-side part of the silica-block copolymer film is evidenced by RBS experiment. On the other hand, by using a thermal method, 40 nm long silver sticks can be obtained, by diffusion and coalescence of spherical particles in the silica-block copolymer layer. In this case, migration of silver particles toward the glass substrate-film interface is shown by the RBS experiment. - Graphical abstract: Growth of silver nanoparticles in a mesostructured block copolymer F127-silica film is performed either by a chemical route involving NaBH{sub 4} reduction or by a thermal method. An array of spherical silver nanoparticles with 10 nm diameter on the upper-side of the mesostructured film or silver sticks long of 40 nm with a preferential orientation are obtained according to the method used. a: TEM image of the Fag5SiNB sample illustrating the silver nanoparticles array obtained by the chemical process; b: HR-TEM image of the Fag20Sid2 sample illustrating the silver nanosticks obtained by the thermal process.

  8. Development of pH Sensitive Nanoparticles for Intestinal Drug Delivery Using Chemically Modified Guar Gum Co-Polymer.

    PubMed

    Varma, Vegesna Naga Sravan Kumar; Shivakumar, Hosakote Gurumalappa; Balamuralidhara, Veerna; Navya, Manne; Hani, Umme

    2016-01-01

    The aim of the research work was to chemically modify guargum (GG) as a pH sensitive co-polymer and formulating intestinal targeting ESO nanoparticles (NPs) using the synthesized co-polymer. Poly acrylamide-grafted-guar gum (PAAm-g-GG) co-polymer was synthesized by free radical polymerization. Chemical modification of PAAm-g-GG by alkaline hydrolysis results in formation of a pH-sensitive co-polymer. The effect of GG and acryl amide (AAm) on grafting was studied. Esomeprazole magnesium (ESO) loaded pH sensitive NPs were prepared by nano-emulsification polymer crosslinking method and characterized. Sixteen formulations were prepared and the concentration of process variables wasvaried to obtain nanoparticles of 200-600 nm. The NPs were found to be homogenous in size distribution. The encapsulation efficiency and drug loading ranged from 33.2% to 50.1% and 12.2% to 17.2% respectively. Particle size, encapsulation efficiency and drug loading increasedalong with co-polymer concentration. In-vitro release studies at pH 1.2 for 2 h, followed by pH 6.8 showed that environment pH significantly affected the drug release. SEM has shown that NPsare spherical with smooth surface. The pH sensitive PAAm-g-GGNPs resisted the initial release of the drug from the drug loaded NPs in acidic pH and delayed the release process to a longer period in alkaline environment. PMID:27610149

  9. Development of pH Sensitive Nanoparticles for Intestinal Drug Delivery Using Chemically Modified Guar Gum Co-Polymer

    PubMed Central

    Varma, Vegesna Naga Sravan Kumar; Shivakumar, Hosakote Gurumalappa; Balamuralidhara, Veerna; Navya, Manne; Hani, Umme

    2016-01-01

    The aim of the research work was to chemically modify guargum (GG) as a pH sensitive co-polymer and formulating intestinal targeting ESO nanoparticles (NPs) using the synthesized co-polymer. Poly acrylamide-grafted-guar gum (PAAm-g-GG) co-polymer was synthesized by free radical polymerization. Chemical modification of PAAm-g-GG by alkaline hydrolysis results in formation of a pH-sensitive co-polymer. The effect of GG and acryl amide (AAm) on grafting was studied. Esomeprazole magnesium (ESO) loaded pH sensitive NPs were prepared by nano-emulsification polymer crosslinking method and characterized. Sixteen formulations were prepared and the concentration of process variables wasvaried to obtain nanoparticles of 200-600 nm. The NPs were found to be homogenous in size distribution. The encapsulation efficiency and drug loading ranged from 33.2% to 50.1% and 12.2% to 17.2% respectively. Particle size, encapsulation efficiency and drug loading increasedalong with co-polymer concentration. In-vitro release studies at pH 1.2 for 2 h, followed by pH 6.8 showed that environment pH significantly affected the drug release. SEM has shown that NPsare spherical with smooth surface. The pH sensitive PAAm-g-GGNPs resisted the initial release of the drug from the drug loaded NPs in acidic pH and delayed the release process to a longer period in alkaline environment. PMID:27610149

  10. Effect of molecular properties of block copolymers and nanoparticles on the morphology of self-assembled bulk nanocomposites.

    SciTech Connect

    Lo, C.-T.; Lee, B.; Dietz Rago, N. L.; Seifert, S.; Winans, R. E.; Thiyagarajan, P.

    2007-11-13

    Self-assembly of thiol-terminated polystyrene-tethered Au nanoparticles in microphase-separated diblock copolymers composed of poly(styrene-b-2vinylpyridine) (PS-PVP) as a function of particle concentration and composition of block copolymers was investigated using anomalous small-angle X-ray scattering (ASAXS) and transmission electron microscopy (TEM). Results reveal that the self-assembly of nanoparticles in the PS domain causes swelling and increases the interfacial curvature that, in turn, induces order-order transitions. At intermediate loading, the presence of nanoparticles amplifies the local compositional fluctuations, hence the roughness at the PS and PVP interface, which creates conditions to induce disorder in the polymer morphology. The system thus undergoes an order-disorder transition. At high particle loading, packing constraints prevent all particles from assembling in the PS domain, and the excess nanoparticles undergo macrophase separation. The present systematic study augments experimental data to the scarce literature on the phase behavior of bulk nanocomposites. We present a generalized phase map for the bulk composites as a function of effective volume fraction of PS (F{sub PS}) for a given nanoparticle size. We believe that the results from this study will enable comparison of the phase maps from various studies and will serve to validate the simulation studies of inorganic particle/block copolymer composites.

  11. Effects of amphiphilic diblock copolymer on drug nanoparticle formation and stability

    PubMed Central

    Zhu, Zhengxi

    2013-01-01

    This study systematically compares the effects of amphiphilic diblock copolymer (di-BCP) on stabilizing hydrophobic drug nanoparticles formed by flash nanoprecipitation (FNP), and provides a guideline on choosing suitable di-BCPs. Four widely used di-BCPs, i.e., polystyrene-block-poly(ethylene glycol) (PS-b-PEG), polycaprolactone-block-poly(ethylene glycol) (PCL-b-PEG), polylactide-block-poly(ethylene glycol) (PLA-b-PEG), and poly(lactic-co-glycolic acid) (PLGA-b-PEG), and β-carotene as a model drug were used. The study showed that PLGA-b-PEG was the most suitable one, whose hydrophobic block was biodegradable and noncrystallizable as well as had relatively high glass transition temperature (Tg) and a right solubility parameter (δ). The molecular weight of PLGA block over the range from 5k to 15k showed an insignificant effect on controlling the particle size. Amorphous drug particles with a high drug loading of over 83 wt% can be achieved. Much remarkable evidence supported the nanoparticles with kinetically frozen and nonequilibrium packing structures of polymer chains rather than either the micelles or micellar nanoparticles with two well segregated polymer blocks. The thermodynamic effects of the drug and BCP on the particle stability, size and structures were discussed by using solubility parameters. PMID:24070569

  12. Robustness of Pluronic Block Copolymer Nanostructure to Structural Changes in Dispersed Nanoparticles

    NASA Astrophysics Data System (ADS)

    Lafollette, Theresa A.; Walker, Lynn M.

    2009-03-01

    Thermoreversible block copolymers [(PEO)n-(PPO)m-(PEO)n; trade name Pluronic] self assemble into ordered micelle gels. Nanoparticles (3-10nm) are templated in the interstitial spaces of Pluronic micelle gels to form nanocomposite systems. Globular hydrophilic proteins have served as model monodisperse nanoparticles in this work. We have shown that these proteins are templated in the interstitial sites of the cubic packed micelle gels at room temperature. By raising the temperature, the proteins are denatured to study the robustness of the micelle gel to structural changes due to the unfolded protein. Nanoscale structure is determined from small angle neutron scattering (SANS). It was expected that any change in the nanoparticle size would cause a change in the packing of the Pluronic micelle gel. However in SANS experiments, the FCC and BCC Pluronic templates show no nanoscale structural differences between a room temperature sample and a sample that has been heated to denature the protein and then cooled back to room temperature. There is a change in the template at longer length scales as evidenced by a low q upturn in the scattered intensity. The robustness of the micelle gel at different length scales will be discussed.

  13. Controlled assembly of plasmonic nanoparticles using neutral-charged diblock copolymers.

    PubMed

    Yin, Quanyi; Han, Xia; Ponsinet, Virginie; Liu, Honglai

    2014-10-01

    In this study, our aim was to control the assembly of plasmonic nanoparticles by using the electrostatic assembly of oppositely charged colloidal species. Gold nanoparticles (Au NPs) were modified with a carboxyl-terminated polymeric ligand, O-(2-carboxyethyl)-O'-(2-mercaptoethyl) heptaethylene glycol (SH-PEG7-COOH), so that they are negatively charged on the pH range 5-10 and they stand elevated ionic strength (up to 1M NaCl) without loss of colloidal stability. Block copolymers poly[(ethylene glycol) methyl ether-block-(N,N-dimethylamino-2-ethyl methacrylate)] (mPEG-PDMAEMA), with a neutral mPEG block and a pH-sensitive positively charged PDMAEMA block were synthesized by atom transfer radical polymerization (ATRP). The formation of complexes, driven by the electrostatic attraction between opposite charges and by the release of the condensed counter ions, was investigated using dynamic light scattering and spectrophotometry. The relative quantities of polymer chains and nanoparticles in the suspension were shown to affect the size of the formed complexes. In this report, it is also shown that the complex formation is reversible. Stable complexes of typical size 400 nm were formed, which could be used as building blocks for new optical materials. PMID:24992300

  14. Thermoresponsive Nanoparticles of Self-Assembled Block Copolymers as Potential Carriers for Drug Delivery and Diagnostics.

    PubMed

    Rahikkala, Antti; Aseyev, Vladimir; Tenhu, Heikki; Kauppinen, Esko I; Raula, Janne

    2015-09-14

    Thermally responsive hydrogel nanoparticles composed of self-assembled polystyrene-b-poly(N-isopropylacrylamide)-b-polystyrene block copolymers and fluorescent probe 1-anilinonaphthalene-8-sulfonic acid have been prepared by aerosol flow reactor method. We aimed exploring the relationship of intraparticle morphologies, that were, PS spheres and gyroids embedded in PNIPAm matrix, as well PS-PNIPAm lamellar structure, to probe release in aqueous solution below and above the cloud point temperature (CPT) of PNIPAm. The release was detected by fluorescence emission given by the probe binding to bovine serum albumin. Also, the colloidal behavior of hydrogel nanoparticles at varying temperatures were examined by scattering method. The probe release was faster below than above the CPT from all the morphologies of which gyroidal morphology showed the highest release. Colloidal behavior varied from single to moderately aggregated particles in order spheres-gyroids-lamellar. Hydrogel nanoparticles with tunable intra particle self-assembled morphologies can be utilized designing carrier systems for drug delivery and diagnostics. PMID:26207325

  15. Preventing corona effects: multiphosphonic acid poly(ethylene glycol) copolymers for stable stealth iron oxide nanoparticles.

    PubMed

    Torrisi, V; Graillot, A; Vitorazi, L; Crouzet, Q; Marletta, G; Loubat, C; Berret, J-F

    2014-08-11

    When dispersed in biological fluids, engineered nanoparticles are selectively coated with proteins, resulting in the formation of a protein corona. It is suggested that the protein corona is critical in regulating the conditions of entry into the cytoplasm of living cells. Recent reports describe this phenomenon as ubiquitous and independent of the nature of the particle. For nanomedicine applications, however, there is a need to design advanced and cost-effective coatings that are resistant to protein adsorption and that increase the biodistribution in vivo. In this study, phosphonic acid poly(ethylene glycol) copolymers were synthesized and used to coat iron oxide particles. The copolymer composition was optimized to provide simple and scalable protocols as well as long-term stability in culture media. It is shown that polymers with multiple phosphonic acid functionalities and PEG chains outperform other types of coating, including ligands, polyelectrolytes, and carboxylic acid functionalized PEG. PEGylated particles exhibit moreover exceptional low cellular uptake, of the order of 100 femtograms of iron per cell. The present approach demonstrates that the surface chemistry of engineered particles is a key parameter in the interactions with cells. It also opens up new avenues for the efficient functionalization of inorganic surfaces. PMID:25046557

  16. Magnetic nanoparticles (MNPs) covalently coated by PEO-PPO-PEO block copolymer for drug delivery.

    PubMed

    Wang, Ning; Guan, Yueping; Yang, Liangrong; Jia, Lianwei; Wei, Xuetuan; Liu, Huizhou; Guo, Chen

    2013-04-01

    A stable drug carrier has been prepared by covalently coating magnetic nanoparticles (MNPs) with PEO-PPO-PEO block copolymer Pluronic P85. The particles were characterized by TEM, XRD, DLS, VSM, FTIR, and TGA. A typical product has a 15 nm magnetite core and a 100 nm hydrodynamic diameter with a narrow size distribution and is superparamagnetic with large saturation magnetization (57.102 emu/g) at room temperature. The covalently-coated Pluronic-MNPs (MagPluronics) were proven to be stable in different conditions, such as aqueous solution, 0.2 M PBS solution, and pH 13.5 solution, which would be significant for biological applications. Furthermore, MagPluronics also possess temperature-responsive property acquired from the Pluronic copolymer layer on their surface, which can cause conformational change of Pluronics and improve load and delivery efficiency of the particles. The temperature-controlled loading and releasing of hydrophobic model drug curcumin were tested with these particles. A loading efficiency of 81.3% and a sustained release of more than 4 days were achieved in simulated human body condition. It indicates that the covalently-coated MagPluronics are stable carriers with good drug-loading capacity and controlled-release property. PMID:23305884

  17. Monte Carlo Study of Degenerate Behavior of AB Diblock Copolymer/Nanoparticle under Cylindrical Confinement.

    PubMed

    Wang, Yingying; Han, Yuanyuan; Cui, Jie; Jiang, Wei; Sun, Yingchun

    2016-08-23

    Degenerate behavior (i.e., forming different self-assembled structures for a given block copolymer (BCP) under the same confinement) commonly exists in various confined systems. Understanding degenerate behavior is crucial for precise control over the structures formed by self-assembly systems under confinement. In this study, the degenerate behavior of a self-assembled AB diblock copolymer/nanoparticle (NP) mixture in a cylindrical pore is studied using Monte Carlo simulation. We find that the degenerate behavior of such a mixture depends on the introduction of the NP. Under different pore sizes, four typical degenerate structures [i.e., single helices (S-helices), double helices (D-helices), parallel cylinders, and stacked toroids] can be obtained if the NP content is zero. However, when the NP content in the mixture is increased, it is found that the number of degenerate structures decreases, that is, only blocky structures can be obtained in the case of high NP content. Moreover, the probability of forming S-helices decreases, whereas the probability of forming D-helices increases with increase in the NP content. Analysis of the interactive enthalpy densities and the chain conformation of the systems indicates that entropy plays an important role in the degenerate structure formation. This study provides some new insights into the degenerate behavior of a BCP/NP mixture under confinement, which can offer a theoretical reference for further experiments. PMID:27459708

  18. Development of stevioside Pluronic-F-68 copolymer based PLA-nanoparticles as an antidiabetic nanomedicine.

    PubMed

    Barwal, Indu; Sood, Anil; Sharma, Mohit; Singh, Bikram; Yadav, Subhash C

    2013-01-01

    Stevioside (FDA approved nontoxic natural non-caloric sweetener) has been reported to have very good antidiabetic potential but its use as therapeutic drug is restricted in human due to its deprived intestinal absorption and poor bioavailability. We have nano-bioconjugated this molecule on biodegradable Pluronic-F-68 copolymer based PLA nanoparticles by nanoprecipitation method (spherical, size range 110-130 nm) to overcome deprived intestinal absorption and to enhance the bioavailability. The drug loading calculated by the standard calibrated HPLC was 16.32±4% (w/w). The in vitro release study showed the initial burst followed by the sustained release. The half release and complete release were observed on 25±4 h and 200±10 h respectively. This newly formulated nanostevioside showed very high potential to be used as antidiabetic nanomedicine for safe and effective use in vivo. PMID:23022553

  19. Hollow Block Copolymer Nanoparticles through a Spontaneous One-Step Structural Reorganization

    PubMed Central

    Petzetakis, Nikos; Robin, Mathew P.; Patterson, Joseph P.; Kelley, Elizabeth G.; Cotanda, Pepa; Bomans, Paul H. H.; Sommerdijk, Nico A. J. M.; Dove, Andrew P.; Epps, Thomas H.; O'Reilly, Rachel K.

    2013-01-01

    The spontaneous one-step synthesis of hollow nanocages and nanotubes from spherical and cylindrical micelles based on poly(acrylic acid)-b-polylactide (P(AA)-b-P(LA)) block copolymers (BCPs) has been achieved. This structural reorganization, which occurs simply upon drying of the samples, was elucidated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). We show that it was necessary to use stain-free imaging to examine these nanoscale assemblies, as the hollow nature of the particles was obscured by application of a heavy metal stain. Additionally, the internal topology of the P(AA)-b-P(LA) particles could be tuned by manipulating the drying conditions to give solid or compartmentalized structures. Upon re-suspension, these reorganized nanoparticles retain their hollow structure and can be display significantly enhanced loading of a hydrophobic dye compared to the original cylinders. PMID:23391297

  20. Preparation and photocatalytic activity of eccentric Au-titania core-shell nanoparticles by block copolymer templates.

    PubMed

    Li, Xue; Fu, Xiaoning; Yang, Hui

    2011-02-21

    A novel route for a preparation of eccentric Au-titania core-shell nanoparticles using gold nanoparticles (AuNPs) with block copolymer shells as a template is reported. AuNPs with poly(2-vinyl pyridine)-block-poly(ethylene oxide) (PVP-b-PEO) block copolymer shells are first prepared by UV irradiation of the solution of PVP-b-PEO/HAuCl(4) complexes. Then the sol-gel reaction of titanium tetra-isopropoxide (TTIP) selectively on the surfaces of AuNPs leads to Au-titania core-shell composite nanoparticles. The eccentric Au-titania core-shell nanoparticles are obtained from the Au-titania core-shell composite nanoparticles by removal of organic interlayer by UV treatment. Photocatalytic activities of the resulting eccentric core-shell nanoparticles are investigated in terms of the degradation of methylene blue (MB). The results show that the eccentric core-shell structures endow the catalyst with greatly enhanced photocatalytic activity. PMID:21157597

  1. Thermally Tunable Metallodielectric Photonic Crystals from Self-assembly of Brush Block Copolymers and Gold Nanoparticles

    NASA Astrophysics Data System (ADS)

    Song, Dongpo; Li, Cheng; Colella, Nicholas; Lu, Xuemin; Watkins, James

    2015-03-01

    Photonic crystals (PCs) based on the self-assembly of block copolymers (BCPs) are under intense investigations, providing new opportunities for simple fabrication of flexible photonic devices or coatings in an inexpensive and scalable way. The precise control and selective incorporation of inorganic nanoparticles (NPs) into specific domains of the microphase separated BCPs can be used to tune the optical constant of the target domains and create hybrid materials with unique optical properties. In this work, we demonstrate a simple strategy for rapid fabrication of well-ordered metallodielectric 1-D PCs using PS- b-PEO brush BCPs as the templates and H-bonding as the driving force for selective incorporation of phenol-coated gold nanoparticles (NPs) into PEO domains. By varying gold NP loading or molecular weight of the brush BCP, periodic layered metallodielectric structures with the domain spacing controlled from 120 nm to 261 nm were readily created resulting in reflection of light widely tunable from the visible to near IR regions (458-1010 nm). The control over size as well as the distribution of the gold NPs in the well-ordered structure was realized through simple thermal treatment, showing significant effects on the optical properties. This work was supported by the NSF Center for Hierarchical Manufacturing at the University of Massachusetts (CMMI-1025020).

  2. Incorporating Diblock Copolymer Nanoparticles into Calcite Crystals: Do Anionic Carboxylate Groups Alone Ensure Efficient Occlusion?

    PubMed Central

    2016-01-01

    New spherical diblock copolymer nanoparticles were synthesized via RAFT aqueous dispersion polymerization of 2-hydroxypropyl methacrylate (HPMA) at 70 °C and 20% w/w solids using either poly(carboxybetaine methacrylate) or poly(proline methacrylate) as the steric stabilizer block. Both of these stabilizers contain carboxylic acid groups, but poly(proline methacrylate) is anionic above pH 9.2, whereas poly(carboxybetaine methacrylate) has zwitterionic character at this pH. When calcite crystals are grown at an initial pH of 9.5 in the presence of these two types of nanoparticles, it is found that the anionic poly(proline methacrylate)-stabilized particles are occluded uniformly throughout the crystals (up to 6.8% by mass, 14.0% by volume). In contrast, the zwitterionic poly(carboxybetaine methacrylate)-stabilized particles show no signs of occlusion into calcite crystals grown under identical conditions. The presence of carboxylic acid groups alone therefore does not guarantee efficient occlusion: overall anionic character is an additional prerequisite. PMID:27042383

  3. Bespoke contrast-matched diblock copolymer nanoparticles enable the rational design of highly transparent Pickering double emulsions

    NASA Astrophysics Data System (ADS)

    Rymaruk, Matthew J.; Thompson, Kate L.; Derry, Matthew J.; Warren, Nicholas J.; Ratcliffe, Liam P. D.; Williams, Clive N.; Brown, Steven L.; Armes, Steven P.

    2016-07-01

    We report the preparation of highly transparent oil-in-water Pickering emulsions using contrast-matched organic nanoparticles. This is achieved via addition of judicious amounts of either sucrose or glycerol to an aqueous dispersion of poly(glycerol monomethacrylate)56-poly(2,2,2-trifluoroethyl methacrylate)500 [PGMA-PTFEMA] diblock copolymer nanoparticles prior to high shear homogenization with an equal volume of n-dodecane. The resulting Pickering emulsions comprise polydisperse n-dodecane droplets of 20-100 μm diameter and exhibit up to 96% transmittance across the visible spectrum. In contrast, control experiments using non-contrast-matched poly(glycerol monomethacrylate)56-poly(benzyl methacrylate)300 [PGMA56-PBzMA300] diblock copolymer nanoparticles as a Pickering emulsifier only produced conventional highly turbid emulsions. Thus contrast-matching of the two immiscible phases is a necessary but not sufficient condition for the preparation of highly transparent Pickering emulsions: it is essential to use isorefractive nanoparticles in order to minimize light scattering. Furthermore, highly transparent oil-in-water-in-oil Pickering double emulsions can be obtained by homogenizing the contrast-matched oil-in-water Pickering emulsion prepared using the PGMA56-PTFEMA500 nanoparticles with a contrast-matched dispersion of hydrophobic poly(lauryl methacrylate)39-poly(2,2,2-trifluoroethyl methacrylate)800 [PLMA39-PTFEMA800] diblock copolymer nanoparticles in n-dodecane. Finally, we show that an isorefractive oil-in-water Pickering emulsion enables fluorescence spectroscopy to be used to monitor the transport of water-insoluble small molecules (pyrene and benzophenone) between n-dodecane droplets. Such transport is significantly less efficient than that observed for the equivalent isorefractive surfactant-stabilized emulsion. Conventional turbid emulsions do not enable such a comparison to be made because the intense light scattering leads to substantial spectral

  4. Bespoke contrast-matched diblock copolymer nanoparticles enable the rational design of highly transparent Pickering double emulsions.

    PubMed

    Rymaruk, Matthew J; Thompson, Kate L; Derry, Matthew J; Warren, Nicholas J; Ratcliffe, Liam P D; Williams, Clive N; Brown, Steven L; Armes, Steven P

    2016-08-14

    We report the preparation of highly transparent oil-in-water Pickering emulsions using contrast-matched organic nanoparticles. This is achieved via addition of judicious amounts of either sucrose or glycerol to an aqueous dispersion of poly(glycerol monomethacrylate)56-poly(2,2,2-trifluoroethyl methacrylate)500 [PGMA-PTFEMA] diblock copolymer nanoparticles prior to high shear homogenization with an equal volume of n-dodecane. The resulting Pickering emulsions comprise polydisperse n-dodecane droplets of 20-100 μm diameter and exhibit up to 96% transmittance across the visible spectrum. In contrast, control experiments using non-contrast-matched poly(glycerol monomethacrylate)56-poly(benzyl methacrylate)300 [PGMA56-PBzMA300] diblock copolymer nanoparticles as a Pickering emulsifier only produced conventional highly turbid emulsions. Thus contrast-matching of the two immiscible phases is a necessary but not sufficient condition for the preparation of highly transparent Pickering emulsions: it is essential to use isorefractive nanoparticles in order to minimize light scattering. Furthermore, highly transparent oil-in-water-in-oil Pickering double emulsions can be obtained by homogenizing the contrast-matched oil-in-water Pickering emulsion prepared using the PGMA56-PTFEMA500 nanoparticles with a contrast-matched dispersion of hydrophobic poly(lauryl methacrylate)39-poly(2,2,2-trifluoroethyl methacrylate)800 [PLMA39-PTFEMA800] diblock copolymer nanoparticles in n-dodecane. Finally, we show that an isorefractive oil-in-water Pickering emulsion enables fluorescence spectroscopy to be used to monitor the transport of water-insoluble small molecules (pyrene and benzophenone) between n-dodecane droplets. Such transport is significantly less efficient than that observed for the equivalent isorefractive surfactant-stabilized emulsion. Conventional turbid emulsions do not enable such a comparison to be made because the intense light scattering leads to substantial spectral

  5. Block Copolymer-Encapsulated CaWO4 Nanoparticles: Synthesis, Formulation, and Characterization.

    PubMed

    Lee, Jaewon; Rancilio, Nicholas J; Poulson, Jean M; Won, You-Yeon

    2016-04-01

    We envision that CaWO4 (CWO) nanocrystals have the potential for use in biomedical imaging and therapy because of the unique ways this material interacts with high-energy radiation. These applications, however, require development of nanoparticle (NP) formulations that are suitable for in vivo applications; primarily, the formulated nanoparticles should be sufficiently small, chemically and biologically inert, and stable against aggregation under physiological conditions. The present study demonstrates one such method of formulation, in which CWO nanoparticles are encapsulated in bioinert block copolymer (BCP) micelles. For this demonstration, we prepared three different CWO nanocrystal samples having different sizes (3, 10, and 70 nm in diameter) and shapes (elongated vs truncated rhombic). Depending on the specific synthesis method used, the as-synthesized CWO NPs contain different surfactant materials (citric acid or cetyltrimethylammonium bromide or a mixture of oleic acid and oleylamine) in the coating layers. Regardless of the type of surfactant, the original surfactant coating can be replaced with a new enclosure formed by BCP materials using a solvent-exchange method. Two types of BCPs have been tested: poly(ethylene glycol-block-n-butyl acrylate) (PEG-PnBA) and poly(ethylene glycol-block-d,l-lactic acid) (PEG-PLA). Both BCPs are able to produce fully PEGylated CWO NPs that are stable against aggregation under physiological salt conditions for very long periods of time (at least three months). The optical and radio luminescence properties of both BCP-encapsulated and surfactant-coated CWO NPs were extensively characterized. The study confirms that the BCP coating structure does not influence the luminescence properties of CWO NPs. PMID:26998964

  6. Peptide-directed self-assembly of functionalized polymeric nanoparticles part I: design and self-assembly of peptide-copolymer conjugates into nanoparticle fibers and 3D scaffolds.

    PubMed

    Ding, Xiaochu; Janjanam, Jagadeesh; Tiwari, Ashutosh; Thompson, Martin; Heiden, Patricia A

    2014-06-01

    A robust self-assembly of nanoparticles into fibers and 3D scaffolds is designed and fabricated by functionalizing a RAFT-polymerized amphiphilic triblock copolymer with designer ionic complementary peptides so that the assembled core-shell polymeric nanoparticles are directed by peptide assembly into continuous "nanoparticle fibers," ultimately leading to 3D fiber scaffolds. The assembled nanostructure is confirmed by FESEM and optical microscopy. The assembly is not hindered when a protein (insulin) is incorporated within the nanoparticles as an active ingredient. MTS cytotoxicity tests on SW-620 cell lines show that the peptides, copolymers, and peptide-copolymer conjugates are biocompatible. The methodology of self-assembled nanoparticle fibers and 3D scaffolds is intended to combine the advantages of a flexible hydrogel scaffold with the versatility of controlled release nanoparticles to offer unprecedented ability to incorporate desired drug(s) within a self-assembled scaffold system with individual control over the release of each drug. PMID:24610743

  7. Thin polymer films of block copolymers and blend/nanoparticle composites

    NASA Astrophysics Data System (ADS)

    Kalloudis, Michail

    In this thesis, atomic force microscopy (AFM), transmission electron microscopy (TEM) and optical microscopy techniques were used to investigate systematically the self-assembled nanostructure behaviour of two different types of spin-cast polymer thin films: poly(isoprene-b-ethylene oxide), PI-b-PEO diblock copolymers and [poly(9,9-dioctylfluorene-co-benzothiadiazole)]:poly[9,9- dioctyfluorene-co-N-(4-butylphenyl)-diphenylamine], F8BT:TFB conjugated polymer blends. In the particular case of the polymer blend thin films, the morphology of their composites with cadmium selenide (CdSe) quantum dot (QD) nanoparticles was also investigated. For the diblock copolymer thin films, the behaviour of the nanostructures formed and the wetting behaviour on mica, varying the volume fraction of the PEO block (fPEO) and the average film thickness was explored. For the polymer blend films, the effect of the F8BT/TFB blend ratio (per weight), spin-coating parameters and solution concentration on the phase-separated nanodomains was investigated. The influence of the quantum dots on the phase separation when these were embedded in the F8BT:TFB thin films was also examined. It was found that in the case of PI-b-PEO copolymer thin films, robust nanostructures, which remained unchanged after heating/annealing and/or ageing, were obtained immediately after spin coating on hydrophilic mica substrates from aqueous solutions. The competition and coupling of the PEO crystallisation and the phase separation between the PEO and PI blocks determined the ultimate morphology of the thin films. Due to the great biocompatible properties of the PEO block (protein resistance), robust PEO-based nanostructures find important applications in the development of micro/nano patterns for biological and biomedical applications. It was also found that sub-micrometre length-scale phase-separated domains were formed in F8BT:TFB spin cast thin films. The nanophase-separated domains of F8BT-rich and TFB-rich areas

  8. Thermally-induced transition of lamellae orientation in block-copolymer films on ‘neutral’ nanoparticle-coated substrates

    DOE PAGESBeta

    Yager, Kevin G.; Forrey, Christopher; Singh, Gurpreet; Satija, Sushil K.; Page, Kirt A.; Patton, Derek L.; Jones, Ronald L.; Karin, Alamgir; Douglas, Jack F.

    2015-06-01

    Block-copolymer orientation in thin films is controlled by the complex balance between interfacial free energies, including the inter-block segregation strength, the surface tensions of the blocks, and the relative substrate interactions. While block-copolymer lamellae orient horizontally when there is any preferential affinity of one block for the substrate, we recently described how nanoparticle-roughened substrates can be used to modify substrate interactions. We demonstrate how such ‘neutral’ substrates can be combined with control of annealing temperature to generate vertical lamellae orientations throughout a sample, at all thicknesses. We observe an orientational transition from vertical to horizontal lamellae upon heating, as confirmedmore » using a combination of atomic force microscopy (AFM), neutron reflectometry (NR) and rotational small-angle neutron scattering (RSANS). Using molecular dynamics (MD) simulations, we identify substrate-localized distortions to the lamellar morphology as the physical basis of the novel behavior. In particular, under strong segregation conditions, bending of horizontal lamellae induce a large energetic cost. At higher temperatures, the energetic cost of conformal deformations of lamellae over the rough substrate is reduced, returning lamellae to the typical horizontal orientation. Thus, we find that both surface interactions and temperature play a crucial role in dictating block-copolymer lamellae orientation. As a result, our combined experimental and simulation findings suggest that controlling substrate roughness should provide a useful and robust platform for controlling block-copolymer orientation in applications of these materials.« less

  9. Thermally-induced transition of lamellae orientation in block-copolymer films on ‘neutral’ nanoparticle-coated substrates

    SciTech Connect

    Yager, Kevin G.; Forrey, Christopher; Singh, Gurpreet; Satija, Sushil K.; Page, Kirt A.; Patton, Derek L.; Jones, Ronald L.; Karin, Alamgir; Douglas, Jack F.

    2015-06-01

    Block-copolymer orientation in thin films is controlled by the complex balance between interfacial free energies, including the inter-block segregation strength, the surface tensions of the blocks, and the relative substrate interactions. While block-copolymer lamellae orient horizontally when there is any preferential affinity of one block for the substrate, we recently described how nanoparticle-roughened substrates can be used to modify substrate interactions. We demonstrate how such ‘neutral’ substrates can be combined with control of annealing temperature to generate vertical lamellae orientations throughout a sample, at all thicknesses. We observe an orientational transition from vertical to horizontal lamellae upon heating, as confirmed using a combination of atomic force microscopy (AFM), neutron reflectometry (NR) and rotational small-angle neutron scattering (RSANS). Using molecular dynamics (MD) simulations, we identify substrate-localized distortions to the lamellar morphology as the physical basis of the novel behavior. In particular, under strong segregation conditions, bending of horizontal lamellae induce a large energetic cost. At higher temperatures, the energetic cost of conformal deformations of lamellae over the rough substrate is reduced, returning lamellae to the typical horizontal orientation. Thus, we find that both surface interactions and temperature play a crucial role in dictating block-copolymer lamellae orientation. As a result, our combined experimental and simulation findings suggest that controlling substrate roughness should provide a useful and robust platform for controlling block-copolymer orientation in applications of these materials.

  10. Amphiphilic block copolymer-stabilized PtRu nanoparticles highly dispersed on multi-walled carbon nanotube for methanol oxidation.

    PubMed

    Guo, Dao-Jun; Cai, Peng; You, Jin-Mao

    2012-02-15

    We report a one-pot synthesis of amphiphilic block copolymer-stabilized PtRu nanoparticle modified multi-walled carbon nanotubes (MWCNTs) using RuCl(3)·xH(2)O and H(2)PtCl(6)·6H(2)O as ruthenium and platinum sources, and block copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) as stabilizer agent. PtRu alloyed nanoparticles with an average diameter of 4.6nm are well decorated homogeneously on the exterior surfaces of the MWCNTs. The electrochemical catalytic activity for methanol oxidation of PtRu/MWCNTs and commercial PtRu/C (E-TEK) is comparatively investigated using cyclic voltammetry and chronoamperometry. It is revealed that the PtRu nanoparticle modified MWCNT samples display an enhanced electrochemical catalytic activity than commercial PtRu/C electrode. These results show that PtRu nanoparticles may find applications to fuel cells. PMID:22104276

  11. Hierarchical Nanoparticle Topography in Amphiphilic Copolymer Films Controlled by Thermodynamics and Dynamics

    PubMed Central

    Caporizzo, M. A.; Ezzibdeh, R. M.

    2016-01-01

    This study systematically investigates how polymer composition changes nanoparticle (NP) grafting and diffusion in solvated random copolymer thin films. By thermal annealing from 135 to 200 °C, thin films with a range of hydrophobicity are generated by varying acrylic acid content from 2% (SAA2) to 29% (SAA29). Poly(styrene-random-tert butyl acrylate) films, 100 nm thick, that are partially converted to poly(styrene-random-acrylic acid), SAA, reversibly swell in ethanol solutions containing amine-functionalized SiO2 nanoparticles with a diameter of 45 nm. The thermodynamics and kinetics of NP grafting are directly controlled by the AA content in the SAA films. At low AA content, namely SAA4, NP attachment saturates at a monolayer, consistent with a low solubility of NPs in SAA4 due to a weakly negative χ parameter. When the AA content exceeds 4%, NPs sink into the film to form multilayers. These films exhibit hierarchical surface roughness with a RMS roughness greater than the NP size. Using a quartz crystal microbalance, NP incorporation in the film is found to saturate after a mass equivalence of about 3 close-packed layers of NPs have been incorporated within the SAA. The kinetics of NP grafting is observed to scale with AA content. The surface roughness is greatest at intermediate times (5–20 min) for SAA13 films, which also exhibit superhydrophobic wetting. Because clustering and aggregation of the NPs within SAA29 films reduce film transparency, SAA13 films provide both maximum hydrophobicity and transparency. The method in this study is widely applicable because it can be applied to many substrate types, can cover large areas, and retains the amine functionality of the particles which allows for subsequent chemical modification. PMID:25689222

  12. Hierarchical nanoparticle topography in amphiphilic copolymer films controlled by thermodynamics and dynamics.

    PubMed

    Caporizzo, M A; Ezzibdeh, R M; Composto, R J

    2015-03-17

    This study systematically investigates how polymer composition changes nanoparticle (NP) grafting and diffusion in solvated random copolymer thin films. By thermal annealing from 135 to 200 °C, thin films with a range of hydrophobicity are generated by varying acrylic acid content from 2% (SAA2) to 29% (SAA29). Poly(styrene-random-tert butyl acrylate) films, 100 nm thick, that are partially converted to poly(styrene-random-acrylic acid), SAA, reversibly swell in ethanol solutions containing amine-functionalized SiO2 nanoparticles with a diameter of 45 nm. The thermodynamics and kinetics of NP grafting are directly controlled by the AA content in the SAA films. At low AA content, namely SAA4, NP attachment saturates at a monolayer, consistent with a low solubility of NPs in SAA4 due to a weakly negative χ parameter. When the AA content exceeds 4%, NPs sink into the film to form multilayers. These films exhibit hierarchical surface roughness with a RMS roughness greater than the NP size. Using a quartz crystal microbalance, NP incorporation in the film is found to saturate after a mass equivalence of about 3 close-packed layers of NPs have been incorporated within the SAA. The kinetics of NP grafting is observed to scale with AA content. The surface roughness is greatest at intermediate times (5-20 min) for SAA13 films, which also exhibit superhydrophobic wetting. Because clustering and aggregation of the NPs within SAA29 films reduce film transparency, SAA13 films provide both maximum hydrophobicity and transparency. The method in this study is widely applicable because it can be applied to many substrate types, can cover large areas, and retains the amine functionality of the particles which allows for subsequent chemical modification. PMID:25689222

  13. Size selective incorporation of gold nanoparticles in diblock copolymer vesicle wall.

    PubMed

    Xu, Jiangping; Han, Yuanyuan; Cui, Jie; Jiang, Wei

    2013-08-20

    A systematic study is conducted to reveal how far the polymeric vesicle wall can embed gold nanoparticles (AuNPs) with different sizes by combining experiments and self-consistent field simulations. Both the experimental and simulative results indicate that the location of AuNPs in vesicle wall or in spherical micelle is heavily size dependent. Whether the AuNPs enter the vesicle wall or not is determined by a ratio of the diameter of AuNPs (D0) to the thickness of the vesicle wall (d(w0)). The 1-dodecanethiol-coated AuNPs (Au(x)R) with D0/d(w0) < 0.3 will stably disperse in the vesicle walls. For polystyrene-coated AuNPs (Au(x)S), a criterion of D0/d(w0) is proposed based on the phase diagram; i.e., the Au(x)S with D0/d(w0) < 0.5 can be located in the vesicle wall. Otherwise, the Au(x)R and the Au(x)S prefer to locate in spherical micelles. Moreover, the contributions of enthalpy and entropy to the total free energy of the system are respectively calculated to reveal the mechanism of the size selective distribution of AuNPs. The results demonstrate that the escape of AuNPs from vesicle walls and their selective distribution in spherical micelles is an entropy-driven process. Our study provides an important guideline for fabricating nanoparticle/block copolymer hybrid vesicles in dilute solution. PMID:23875535

  14. Solvent-induced size reduction of self-assembled siRNA/copolymer nanoparticles

    NASA Astrophysics Data System (ADS)

    Qu, Wei; Wu, Juan; Mao, Hai-Quan; Luijten, Erik

    2013-03-01

    Small interfering RNA (siRNA) therapeutics has a demonstrated potential for treating numerous liver diseases. However, traditional polycation vectors used for siRNA delivery typically produce siRNA-containing particles of large size (> 100 nm), along with high cytotoxicity and low colloidal stability. Inspired by earlier work on nanoparticles for plasmid DNA delivery, we graft hydrophilic and biocompatible polyethylene glycol (PEG) blocks to the polycation vector to overcome these limitations. We find that the PEG-grafted polycations result in slightly larger particle size, even though the hydrophilic PEG blocks are expected to hinder the formation of larger aggregates. To explain this observation, we investigate siRNA/copolymer self-assembly via computer simulations of coarse-grained polymer and siRNA models. Our calculations suggest that hydrogen bonding between PEG and the polycation leads to the increased particle size, and that smaller particles can be obtained by inhibiting hydrogen bonding in such system. Subsequent experiments employing solvents of lower polarity indeed lead to particles with smaller size.

  15. Self-assembly of inorganic nanoparticle vesicles and tubules driven by tethered linear block copolymers.

    PubMed

    He, Jie; Liu, Yijing; Babu, Taarika; Wei, Zengjiang; Nie, Zhihong

    2012-07-18

    Controllable self-assembly of nanoscale building blocks into larger specific structures provides an effective route for the fabrication of new materials with unique optical, electronic, and magnetic properties. The ability of nanoparticles (NPs) to self-assemble like molecules is opening new research frontiers in nanoscience and nanotechnology. We present a new class of amphiphilic "colloidal molecules" (ACMs) composed of inorganic NPs tethered with amphiphilic linear block copolymers (BCPs). Driven by the conformational changes of tethered BCP chains, such ACMs can self-assemble into well-defined vesicular and tubular nanostructures comprising a monolayer shell of hexagonally packed NPs in selective solvents. The morphologies and geometries of these assemblies can be controlled by the size of NPs and molecular weight of BCPs. Our approach also allows us to control the interparticle distance, thus fine-tuning the plasmonic properties of the assemblies of metal NPs. This strategy provides a general means to design new building blocks for assembling novel functional materials and devices. PMID:22746265

  16. Mechanistic Investigation of Seeded Growth in Triblock Copolymer Stabilized Gold Nanoparticles

    PubMed Central

    Sabir, Theodore S.; Rowland, Leah; Milligan, Jamie R.; Yan, Dong; Aruni, A. Wilson; Chen, Qiao; Boskovic, Danilo S.; Kurti, R. Steven; Perry, Christopher C.

    2015-01-01

    We report the seeded synthesis of gold nanoparticles (GNPs) via the reduction of HAuCl4 by (L31 and F68) triblock copolymer (TBP) mixtures. In the present study, we focused on [TBP]/[Au(III)] ratios of 1–5 (≈ 1 mM HAuCl4) and seed sizes ~ 20 nm. Under these conditions, the GNP growth rate is dominated by both the TBP and seed concentrations. With seeding, the final GNP size distributions are bimodal. Increasing the seed concentration (up to ~ 0.1 nM) decreases the mean particle sizes 10-fold, from ~1000 to 100 nm. The particles in the bimodal distribution are formed by the competitive direct growth in solution and the aggregative growth on the seeds. By monitoring kinetics of GNP growth, we propose that (1) the surface of the GNP seeds embedded in the TBP cavities form catalytic centers for GNP growth and; (2) large GNPs are formed by the aggregation of GNP seeds in an autocatalytic growth process. PMID:23473268

  17. Poly(styrene)-b-poly(DL-lactide) copolymer-based nanoparticles for anticancer drug delivery.

    PubMed

    Lee, Jae-Young; Kim, Jung Sun; Cho, Hyun-Jong; Kim, Dae-Duk

    2014-01-01

    Poly(styrene)-b-poly(DL-lactide) (PS-PDLLA) copolymer-based nanoparticles (NPs) of a narrow size distribution, negative zeta potential, and spherical shape were fabricated for the delivery of docetaxel (DCT). The particle size was consistently maintained in serum for 24 hours and a sustained drug release pattern was observed for 10 days in the tested formulations. The cytotoxicity of the developed blank NPs was negligible in prostate cancer (PC-3) cells. Cellular uptake and distribution of the constructed NPs containing a hydrophobic fluorescent dye was monitored by confocal laser scanning microscopy (CLSM) for 24 hours. Anti-tumor efficacy of the PS-PDLLA/DCT NPs in PC-3 cells was significantly more potent than that of the group treated with commercially available DCT, Taxotere (P<0.05). Blood biochemistry tests showed that no serious toxicity was observed with the blank NPs in the liver and kidney. In a pharmacokinetic study of DCT in rats, in vivo clearance of PS-PDLLA/DCT NPs decreased while the half-life in blood increased compared to the Taxotere-treated group (P<0.05). The PS-PDLLA NPs are expected to be a biocompatible and efficient nano-delivery system for anticancer drugs. PMID:24940058

  18. Nature of the Enhancement in Ferroelectric Properties by Gold Nanoparticles in Vinylidene Fluoride and Trifluoroethylene Copolymer.

    PubMed

    Tsutsumi, Naoto; Kosugi, Ryusei; Kinashi, Kenji; Sakai, Wataru

    2016-07-01

    Ferroelectric polymers are a candidate for versatile and cheap data storage memory devices, with easy processing for a large-scale device. Easy switching and large remanent polarization of preferentially formed β-crystal dipoles in a copolymer of vinylidene fluoride and trifluoroethylene (P(VDF-TrFE)) are promising properties for versatile memory devices. At higher frequency switching, however, the remanent polarization is reduced and a high coercive field, an electric field for polarization switching is required. The addition of a small amount of nanoparticles (NPs) significantly improves these ferroelectric properties in fluoropolymers. Here, we show that the addition of NPs of gold (Au), silver (Ag), and silicon oxide (SiO2) enhanced the ferroelectric properties in P(VDF-TrFE). AuNPs significantly affected a 40% increase of the remanent polarization, 14% reduction of the coercive field, and 100% increase of the switching speed of ferroelectric polarization. The nature of these enhancements due to the addition of NPs is verified. A higher shift of the binding energy of Au (4f7/2 and 4f5/2) and an increase of the fluorine ion (F(-)) was observed in AuNP-doped P(VDF-TrFE). Strong interactions between the AuNPs and the ferroelectric backbone gave rise to the formation of the interfacial polarization, which induced the local electric field to enhance the ferroelectric properties of the increment of the remanent polarization, the reduction of the coercive field, and faster switching speed. PMID:27309153

  19. Poly(styrene)-b-poly(DL-lactide) copolymer-based nanoparticles for anticancer drug delivery

    PubMed Central

    Lee, Jae-Young; Kim, Jung Sun; Cho, Hyun-Jong; Kim, Dae-Duk

    2014-01-01

    Poly(styrene)-b-poly(DL-lactide) (PS-PDLLA) copolymer-based nanoparticles (NPs) of a narrow size distribution, negative zeta potential, and spherical shape were fabricated for the delivery of docetaxel (DCT). The particle size was consistently maintained in serum for 24 hours and a sustained drug release pattern was observed for 10 days in the tested formulations. The cytotoxicity of the developed blank NPs was negligible in prostate cancer (PC-3) cells. Cellular uptake and distribution of the constructed NPs containing a hydrophobic fluorescent dye was monitored by confocal laser scanning microscopy (CLSM) for 24 hours. Anti-tumor efficacy of the PS-PDLLA/DCT NPs in PC-3 cells was significantly more potent than that of the group treated with commercially available DCT, Taxotere® (P<0.05). Blood biochemistry tests showed that no serious toxicity was observed with the blank NPs in the liver and kidney. In a pharmacokinetic study of DCT in rats, in vivo clearance of PS-PDLLA/DCT NPs decreased while the half-life in blood increased compared to the Taxotere-treated group (P<0.05). The PS-PDLLA NPs are expected to be a biocompatible and efficient nano-delivery system for anticancer drugs. PMID:24940058

  20. Self-assembly of diblock copolymer-maghemite nanoparticle hybrid thin films.

    PubMed

    Yao, Yuan; Metwalli, Ezzeldin; Moulin, Jean-François; Su, Bo; Opel, Matthias; Müller-Buschbaum, Peter

    2014-10-22

    The arrangement of maghemite (γ-Fe2O3) nanoparticles (NPs) in poly(styrene-d8-block-n-butyl methacrylate) P(Sd-b-BMA) diblock copolymer (DBC) films via a self-assembly process was investigated toward the fabrication of highly ordered maghemite-polymer hybrid thin films. The resulting thin films exhibited a perforated lamella with an enrichment layer containing NPs as investigated with X-ray reflectometry, scanning electron microscopy, atomic force microscopy, and time-of-flight grazing incidence small angle neutron scattering as a function of the NP concentrations. The NPs were selectively deposited in the PSd domains of the DBC during the microphase separation process. At low NP concentrations, the incorporation of the NPs within the DBC thin films resulted in an enhanced microphase separation process and formation of highly oriented and ordered nanostructured hybrid films. At higher NP concentrations, the aggregation of the NPs was dominating and large sized metal oxide clusters were observed. The superparamagnetic properties of the metal oxide-polymer hybrid films at various NP concentrations were probed by a superconducting quantum interference device magnetometer, which shows that the hybrid films are highly attractive for optical devices, magnetic sensors, and magnetic recording devices. PMID:25243575

  1. Dexamethasone-loaded Block Copolymer Nanoparticles Induce Leukemia Cell Death and Enhances Therapeutic Efficacy: A Novel Application in Pediatric Nanomedicine

    PubMed Central

    Krishnan, Vinu; Xu, Xian; Barwe, Sonali P.; Yang, Xiaowei; Czymmek, Kirk; Waldman, Scott A.; Mason, Robert W.; Jia, Xinqiao; Rajasekaran, Ayyappan K.

    2014-01-01

    Nanotechnology approaches have tremendous potential for enhancing treatment efficacy with lower doses of chemotherapeutics. Nanoparticle-based drug delivery approaches are poorly developed for childhood leukemia. Dexamethasone (Dex) is one of the most common chemotherapeutic drugs used in the treatment of childhood leukemia. In this study, we encapsulated Dex in polymeric nanoparticles and validated their anti-leukemic potential in vitro and in vivo. Nanoparticles (NPs) with an average diameter of 110 nm were assembled from amphiphilic block copolymers poly (ethylene glycol) (PEG) and poly (ε-caprolactone) (PCL) bearing pendant cyclic ketals. The blank nanoparticles were non-toxic to cultured cells in vitro and to mice in vivo. Encapsulation of Dex into the nanoparticles (Dex-NP) did not compromise the bioactivity of the drug. Dex-NPs induced glucocorticoid phosphorylation and showed cytotoxicity similar to the free Dex in leukemic cells. Studies using nanoparticles labeled with fluorescent dyes revealed leukemic cell surface binding and internalization. In vivo biodistribution studies showed NP accumulation in the liver and spleen with subsequent clearance of the particles with time. In a pre-clinical model of leukemia, Dex-NPs significantly improved the quality of life and survival of mice compared to the free drug. To our knowledge, this is the first report showing the efficacy of polymeric nanoparticles to deliver Dex to potentially treat childhood leukemia and reveals that low dose of Dex should be sufficient for inducing cell death and improve survival. PMID:23194373

  2. Self-Assembly of Oligosaccharide-b-PMMA Block Copolymer Systems: Glyco-Nanoparticles and Their Degradation under UV Exposure.

    PubMed

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

    2016-05-10

    This paper discusses the self-assembly of oligosaccharide-containing block copolymer and the use of ultraviolet (UV) to obtain nanoporous glyco-nanoparticles by photodegradation of the synthetic polymer block. Those glyco-nanoparticles consisting of oligosaccharide-based shell and a photodegradable core domain were obtained from the self-assembly of maltoheptaose-block-poly(methyl methacrylate) (MH-b-PMMA48) using the nanoprecipitation protocol. MH-b-PMMA48 self-assembled into well-defined spherical micelles (major compound) with a hydrodynamic radius (Rh) of ca. 10 nm and also into large compound micellar aggregates (minor compound) with an Rh of ca. 65 nm. The oligosaccharide shells of these glyco-nanoparticles were cross-linked through the Michael-type addition of divinyl sulfone under dilute conditions to minimize the intermicellar cross-linking. The core domain photodegradation of the cross-linked glyco-nanoparticles was induced under exposure to 254 nm UV radiation, resulting in porous glyco-nanoparticles with an Rh of ca. 44 nm. The morphology of the cross-linked shell and the core photodegradation of these glyco-nanoparticles were characterized using static light scattering, dynamic light scattering, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, field-emission gun-scanning electron microscopy, and transmission electron microscopy. The innovative aspect of this approach concerns the fact that after removing the PMMA domains the porous nanoparticles are mostly composed of biocompatible and nontoxic oligosaccharides. PMID:27054350

  3. The heat-chill method for preparation of self-assembled amphiphilic poly(ε-caprolactone)-poly(ethylene glycol) block copolymer based micellar nanoparticles for drug delivery.

    PubMed

    Payyappilly, Sanal Sebastian; Dhara, Santanu; Chattopadhyay, Santanu

    2014-04-01

    A new method is developed for preparation of amphiphilic block copolymer micellar nanoparticles and investigated as a delivery system for celecoxib, a hydrophobic model drug. Biodegradable block copolymers of poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) were synthesized by ring opening copolymerization and characterized thoroughly using FTIR, (1)H NMR and GPC. The block copolymer was dispersed in distilled water at 60 °C and then it was chilled in an ice bath for the preparation of the micellar nanoparticles. Polymers self-assembled to form micellar nanoparticles (<50 nm) owing to their amphiphilic nature. The prepared micellar nanoparticles were analyzed using HR-TEM, DLS and DSC. The cytotoxicity of the polymer micellar nanoparticles was investigated against HaCaT cell lines. The study of celecoxib release from the micellar nanoparticles was carried out to assess their suitability as a drug delivery vehicle. Addition of the drug to the system at low temperature is an added advantage of this method compared to the other temperature assisted nanoparticle preparation techniques. In a nutshell, polymer micellar nanoparticles prepared using the heat-chill method are believed to be promising for the controlled drug release system of labile drugs, which degrade in toxic organic solvents and at higher temperatures. PMID:24651872

  4. Internal Nanoparticle Structure of Temperature-Responsive Self-Assembled PNIPAM-b-PEG-b-PNIPAM Triblock Copolymers in Aqueous Solutions: NMR, SANS, and Light Scattering Studies.

    PubMed

    Filippov, Sergey K; Bogomolova, Anna; Kaberov, Leonid; Velychkivska, Nadiia; Starovoytova, Larisa; Cernochova, Zulfiya; Rogers, Sarah E; Lau, Wing Man; Khutoryanskiy, Vitaliy V; Cook, Michael T

    2016-05-31

    In this study, we report detailed information on the internal structure of PNIPAM-b-PEG-b-PNIPAM nanoparticles formed from self-assembly in aqueous solutions upon increase in temperature. NMR spectroscopy, light scattering, and small-angle neutron scattering (SANS) were used to monitor different stages of nanoparticle formation as a function of temperature, providing insight into the fundamental processes involved. The presence of PEG in a copolymer structure significantly affects the formation of nanoparticles, making their transition to occur over a broader temperature range. The crucial parameter that controls the transition is the ratio of PEG/PNIPAM. For pure PNIPAM, the transition is sharp; the higher the PEG/PNIPAM ratio results in a broader transition. This behavior is explained by different mechanisms of PNIPAM block incorporation during nanoparticle formation at different PEG/PNIPAM ratios. Contrast variation experiments using SANS show that the structure of nanoparticles above cloud point temperatures for PNIPAM-b-PEG-b-PNIPAM copolymers is drastically different from the structure of PNIPAM mesoglobules. In contrast with pure PNIPAM mesoglobules, where solidlike particles and chain network with a mesh size of 1-3 nm are present, nanoparticles formed from PNIPAM-b-PEG-b-PNIPAM copolymers have nonuniform structure with "frozen" areas interconnected by single chains in Gaussian conformation. SANS data with deuterated "invisible" PEG blocks imply that PEG is uniformly distributed inside of a nanoparticle. It is kinetically flexible PEG blocks which affect the nanoparticle formation by prevention of PNIPAM microphase separation. PMID:27159129

  5. Role of block copolymer adsorption versus bimodal grafting on nanoparticle self-assembly in polymer nanocomposites.

    PubMed

    Zhao, Dan; Di Nicola, Matteo; Khani, Mohammad M; Jestin, Jacques; Benicewicz, Brian C; Kumar, Sanat K

    2016-09-14

    We compare the self-assembly of silica nanoparticles (NPs) with physically adsorbed polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymers (BCP) against NPs with grafted bimodal (BM) brushes comprised of long, sparsely grafted PS chains and a short dense carpet of P2VP chains. As with grafted NPs, the dispersion state of the BCP NPs can be facilely tuned in PS matrices by varying the PS coverage on the NP surface or by changes in the ratio of the PS graft to matrix chain lengths. Surprisingly, the BCP NPs are remarkably better dispersed than the NPs tethered with bimodal brushes at comparable PS grafting densities. We postulate that this difference arises because of two factors inherent in the synthesis of the NPs: In the case of the BCP NPs the adsorption process is analogous to the chains being "grafted to" the NP surface, while the BM case corresponds to "grafting from" the surface. We have shown that the "grafted from" protocol yields patchy NPs even if the graft points are uniformly placed on each particle. This phenomenon, which is caused by chain conformation fluctuations, is exacerbated by the distribution function associated with the (small) number of grafts per particle. In contrast, in the case of BCP adsorption, each NP is more uniformly coated by a P2VP monolayer driven by the strongly favorable P2VP-silica interactions. Since each P2VP block is connected to a PS chain we conjecture that these adsorbed systems are closer to the limit of spatially uniform sparse brush coverage than the chemically grafted case. We finally show that the better NP dispersion resulting from BCP adsorption leads to larger mechanical reinforcement than those achieved with BM particles. These results emphasize that physical adsorption of BCPs is a simple, effective and practically promising strategy to direct NP dispersion in a chemically unfavorable polymer matrix. PMID:27502154

  6. Enhancing Therapeutic Effects of Docetaxel-Loaded Dendritic Copolymer Nanoparticles by Co-Treatment with Autophagy Inhibitor on Breast Cancer

    PubMed Central

    Zhang, Xudong; Yang, Ying; Liang, Xin; Zeng, Xiaowei; Liu, Zhigang; Tao, Wei; Xiao, Xiaojun; Chen, Hongbo; Huang, Laiqiang; Mei, Lin

    2014-01-01

    Dendrimers are synthetic nanocarriers that comprise a highly branched spherical polymer as new, efficient tools for drug delivery. However, the fate of nanocarriers after being internalized into cells has seldom been studied. Docetaxel loaded dendritic copolymer H40-poly(D,L-lactide) nanoparticles, referred to as “DTX-H40-PLA NPs”, were prepared and used as a model to evaluate whether the NPs were sequestered by autophagy and fused with lysosomes. Besides being degraded through the endolysosomal pathway, the DTX-loaded H40-PLA NPs were also sequestered by autophagosomes and degraded through the autolysosomal pathway. DTX-loaded H40-PLA NPs may stop exerting beneficial effects after inducing autophagy of human MCF-7 cancer cells. Co-delivery of autophagy inhibitor such as chloroquine and chemotherapeutic drug DTX by dendritic copolymer NPs greatly enhanced cancer cell killing in vitro, and decreased both the volume and weight of the tumors in severe combined immunodeficient mice. These findings provide valuable evidence for development of nanomedicine such as dendritic copolymer NPs for clinical application. PMID:25285162

  7. In-situ formation of silver nanoparticles stabilized by amphiphilic star-shaped copolymer and their catalytic application

    NASA Astrophysics Data System (ADS)

    Huang, Xiujuan; Xiao, Yan; Zhang, Wei; Lang, Meidong

    2012-01-01

    Silver nanoparticles (Ag NPs) were prepared via in situ reduction of silver nitrate (AgNO3) using polymeric micelles as nanoreactors without any additional reductant. The micelles were constructed from the amphiphilic star-shaped copolymer composed of poly(ɛ-caprolactone) (PCL) segment, 2-(dimethylamino)ethyl methacrylate (DMAEMA or DMA) units and oligo(ethylene glycol)monomethyl ether methacrylate (OEGMA or OEG) units. The Ag NPs stabilized by those star-shaped copolymers were characterized using UV-vis spectrum, DLS, TEM and FTIR. It confirmed that PDMAEMA exhibited the reducing property unless pH was above 7. The Ag NPs were sphere-like with a diameter of 10-20 nm, which was independent of the architecture of the copolymer and AgNO3 concentration. Furthermore, the catalytic activity of these Ag NPs was investigated by monitoring the reduction of p-nitrophenol (4-NP) by NaBH4. The result showed that the Ag NPs formed by coordination reduction can be effectively applied in catalytic reaction.

  8. Fabrication of periodic arrays of metallic nanoparticles by block copolymer templates on HfO2 substrates.

    PubMed

    Frascaroli, Jacopo; Seguini, Gabriele; Spiga, Sabina; Perego, Michele; Boarino, Luca

    2015-05-29

    Block copolymer-based templates can be exploited for the fabrication of ordered arrays of metal nanoparticles (NPs) with a diameter down to a few nanometers. In order to develop this technique on metal oxide substrates, we studied the self-assembly of polymeric templates directly on the HfO₂ surface. Using a random copolymer neutralization layer, we obtained an effective HfO₂ surface neutralization, while the effects of surface cleaning and annealing temperature were carefully examined. Varying the block copolymer molecular weight, we produced regular nanoporous templates with feature size variable between 10 and 30 nm and a density up to 1.5 × 10¹¹ cm⁻². With the adoption of a pattern transfer process, we produced ordered arrays of Pt and Pt/Ti NPs with diameters of 12, 21 and 29 nm and a constant size dispersion (σ) of 2.5 nm. For the smallest template adopted, the NP diameter is significantly lower than the original template dimension. In this specific configuration, the granularity of the deposited film probably influences the pattern transfer process and very small NPs of 12 nm were achieved without a significant broadening of the size distribution. PMID:25948389

  9. PEI-PEG-Chitosan Copolymer Coated Iron Oxide Nanoparticles for Safe Gene Delivery: synthesis, complexation, and transfection**

    PubMed Central

    Kievit, Forrest M.; Veiseh, Omid; Bhattarai, Narayan; Fang, Chen; Gunn, Jonathan W.; Lee, Donghoon; Ellenbogen, Richard G.; Olson, James M.

    2009-01-01

    Gene therapy offers the potential of mediating disease through modification of specific cellular functions of target cells. However, effective transport of nucleic acids to target cells with minimal side effects remains a challenge despite the use of unique viral and non-viral delivery approaches. Here we present a non-viral nanoparticle gene carrier that demonstrates effective gene delivery and transfection both in vitro and in vivo. The nanoparticle system (NP-CP-PEI) is made of a superparamagnetic iron oxide nanoparticle (NP), which enables magnetic resonance imaging, coated with a novel copolymer (CP-PEI) comprised of short chain polyethylenimine (PEI) and poly(ethylene glycol) (PEG) grafted to the natural polysaccharide, chitosan (CP), which allows efficient loading and protection of the nucleic acids. The function of each component material in this nanoparticle system is illustrated by comparative studies of three nanoparticle systems of different surface chemistries, through material property characterization, DNA loading and transfection analyses, and toxicity assessment. Significantly, NP-CP-PEI demonstrates an innocuous toxic profile and a high level of expression of the delivered plasmid DNA in a C6 xenograft mouse model, making it a potential candidate for safe in vivo delivery of DNA for gene therapy. PMID:20160995

  10. Bespoke contrast-matched diblock copolymer nanoparticles enable the rational design of highly transparent Pickering double emulsions

    NASA Astrophysics Data System (ADS)

    Rymaruk, Matthew J.; Thompson, Kate L.; Derry, Matthew J.; Warren, Nicholas J.; Ratcliffe, Liam P. D.; Williams, Clive N.; Brown, Steven L.; Armes, Steven P.

    2016-07-01

    We report the preparation of highly transparent oil-in-water Pickering emulsions using contrast-matched organic nanoparticles. This is achieved via addition of judicious amounts of either sucrose or glycerol to an aqueous dispersion of poly(glycerol monomethacrylate)56-poly(2,2,2-trifluoroethyl methacrylate)500 [PGMA-PTFEMA] diblock copolymer nanoparticles prior to high shear homogenization with an equal volume of n-dodecane. The resulting Pickering emulsions comprise polydisperse n-dodecane droplets of 20-100 μm diameter and exhibit up to 96% transmittance across the visible spectrum. In contrast, control experiments using non-contrast-matched poly(glycerol monomethacrylate)56-poly(benzyl methacrylate)300 [PGMA56-PBzMA300] diblock copolymer nanoparticles as a Pickering emulsifier only produced conventional highly turbid emulsions. Thus contrast-matching of the two immiscible phases is a necessary but not sufficient condition for the preparation of highly transparent Pickering emulsions: it is essential to use isorefractive nanoparticles in order to minimize light scattering. Furthermore, highly transparent oil-in-water-in-oil Pickering double emulsions can be obtained by homogenizing the contrast-matched oil-in-water Pickering emulsion prepared using the PGMA56-PTFEMA500 nanoparticles with a contrast-matched dispersion of hydrophobic poly(lauryl methacrylate)39-poly(2,2,2-trifluoroethyl methacrylate)800 [PLMA39-PTFEMA800] diblock copolymer nanoparticles in n-dodecane. Finally, we show that an isorefractive oil-in-water Pickering emulsion enables fluorescence spectroscopy to be used to monitor the transport of water-insoluble small molecules (pyrene and benzophenone) between n-dodecane droplets. Such transport is significantly less efficient than that observed for the equivalent isorefractive surfactant-stabilized emulsion. Conventional turbid emulsions do not enable such a comparison to be made because the intense light scattering leads to substantial spectral

  11. Growth of block copolymer stabilized metal nanoparticles probed simultaneously by in situ XAS and UV-Vis spectroscopy.

    PubMed

    Nayak, C; Bhattacharyya, D; Jha, S N; Sahoo, N K

    2016-01-01

    The growth of Au and Pt nanoparticles from their respective chloride precursors using block copolymer-based reducers has been studied by simultaneous in situ measurement of XAS and UV-Vis spectroscopy at the energy-dispersive EXAFS beamline (BL-08) at INDUS-2 SRS at RRCAT, Indore, India. While the XANES spectra of the precursor give real-time information on the reduction process, the EXAFS spectra reveal the structure of the clusters formed at the intermediate stages of growth. The growth kinetics of both types of nanoparticles are found to be almost similar and are found to follow three stages, though the first stage of nucleation takes place earlier in the case of Au than in the case of Pt nanoparticles due to the difference in the reduction potential of the respective precursors. The first two stages of the growth of Au and Pt nanoparticles as obtained by in situ XAS measurements could be corroborated by simultaneous in situ measurement of UV-Vis spectroscopy also. PMID:26698077

  12. Distribution of phenanthrene between soil and an aqueous phase in the presence of anionic micelle-like amphiphilic polyurethane particles.

    PubMed

    Lee, Kangtaek; Choi, Heon-Sik; Kim, Ju-Young; Ahn, Ik-Sung

    2003-12-12

    Sorption of micelle-like amphiphilic polyurethane (APU) particles to soil was studied and compared to that of a model anionic surfactant, sodium dodecyl sulfate (SDS). Three types of APU particles with different hydrophobicity were synthesized from urethane acrylate anionomers (UAA) and used in this study. Due to the chemically cross-linked structure, APU exhibited less sorption to the soil than SDS and a greater reduction in the sorption of phenanthrene, a model soil contaminant, to the soil was observed in the presence of APU than SDS even though the solubility of phenanthrene was higher in the presence of SDS than APU. A mathematical model was developed to describe the phenanthrene distribution between soil and an aqueous phase containing APU particles. The sorption of phenanthrene to the test soil could be well described by Linear isotherm. APU sorption to the soil was successfully described by Langmuir and Freundlich isotherms. The partition of phenanthrene between water and APU were successfully explained with a single partition coefficient. The model, which accounts for the limited solubilization of phenanthrene in sorbed APU particles, successfully described the experimental data for the distribution of phenanthrene between the soil and the aqueous phase in the presence of APU. PMID:14623427

  13. Facile Synthesis of Thiol-terminated Poly(styrene-ran-vinyl phenol) (PSVPh) Copolymers via Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization and Their Use in the Synthesis of Gold Nanoparticles with Controllable Hydrophilicity

    SciTech Connect

    Lee, Chang-Uk; Roy, Debashish; Dadmun, Mark D

    2010-01-01

    A facile approach to prepare thiol-terminated poly(styrene-ran-vinyl phenol) (PSVPh) copolymers and PSVPh-coated gold nanoparticles is reported with the goal of creating stabilizing ligands for nanoparticles with controlled hydrophilicity. Dithioester-terminated poly(styrene-ran-acetoxystyrene) copolymers were synthesized via RAFT polymerization using cumyl dithiobenzoate as a chain transfer agent. These copolymers were converted to thiol-terminated PSVPh copolymers by a one step hydrazinolysis reaction using hydrazine hydrate to simultaneously convert dithioester-terminal and acetoxypendant groups to thiol-terminal and hydroxyl-pendant groups, respectively. Spectroscopic observations including NMR and IR confirm end- and pendant-group conversion. PSVPh-coated gold nanoparticles were synthesized in the presence of a mixture of thiol-terminated PSVPh and PSVPh copolymers containing disulfides as stabilizing ligands in a water/toluene, two-phase system. The size and size distribution of core gold nanoparticles were determined by TEM and image analysis. The hydrodynamic radius of PSVPh-coated gold nanoparticles was also determined by dynamic light scattering experiment, which confirms the particle analysis by TEM. This procedure provides a facile technique to control the polarity and hydrophilicity of metal nanoparticle surfaces and could prove critical in advancing the control of nanoparticle placement in biological and hierarchically ordered systems, such as diblock copolymers.

  14. Synthesis, characterization and in vitro studies of doxorubicin-loaded magnetic nanoparticles grafted to smart copolymers on A549 lung cancer cell line

    PubMed Central

    2012-01-01

    Background The aim of present study was to develop the novel methods for chemical and physical modification of superparamagnetic iron oxide nanoparticles (SPIONs) with polymers via covalent bonding entrapment. These modified SPIONs were used for encapsulation of anticancer drug doxorubicin. Method At first approach silane–grafted magnetic nanoparticles was prepared and used as a template for polymerization of the N-isopropylacrylamide (NIPAAm) and methacrylic acid (MAA) via radical polymerization. This temperature/pH-sensitive copolymer was used for preparation of DOX–loaded magnetic nanocomposites. At second approach Vinyltriethoxysilane-grafted magnetic nanoparticles were used as a template to polymerize PNIPAAm-MAA in 1, 4 dioxan and methylene-bis-acrylamide (BIS) was used as a cross-linking agent. Chemical composition and magnetic properties of Dox–loaded magnetic hydrogel nanocomposites were analyzed by FT-IR, XRD, and VSM. Results The results demonstrate the feasibility of drug encapsulation of the magnetic nanoparticles with NIPAAm–MAA copolymer via covalent bonding. The key factors for the successful prepardtion of magnetic nanocomposites were the structure of copolymer (linear or cross-linked), concentration of copolymer and concentration of drug. The influence of pH and temperature on the release profile of doxorubicin was examined. The in vitro cytotoxicity test (MTT assay) of both magnetic DOx–loaded nanoparticles was examined. The in vitro tests showed that these systems are no toxicity and are biocompatible. Conclusion IC50 of DOx–loaded Fe3O4 nanoparticles on A549 lung cancer cell line showed that systems could be useful in treatment of lung cancer. PMID:23244711

  15. Correlating bulk properties and nanoscale rearrangement during UV-initiated gelation of hybrid nanoparticle/ block copolymer systems

    NASA Astrophysics Data System (ADS)

    Juggernauth, K. Anne; Seifert, Soenke; Love, Brian

    2013-03-01

    We use rheology and Small Angle X-Ray Scattering (SAXS) to investigate UV initiated gel formation in aqueous dispersions of clay nanoparticles in the presence of poly(ethyleneoxide-b-propyleneoxide-b-ethyleneoxide) block copolymer surfactants (Pluronics®) and small amounts of a photoacid generator (PAG). This material system demonstrates stable liquid-like behavior in the absence of UV but undergoes bulk gelation upon UV exposure. Rheology was used to monitor the bulk properties of a series of samples undergoing UV exposure and confirm bulk gel formation. We further probe nanoparticle rearrangement using time resolved synchrotron SAXS with simultaneous UV exposure. Time dependent SAXS indicate an absence of long range order and crystallinity while changes in the scattering profile are related to short range interparticle interactions leading to a stable or arrested structure. Finally, we compare the time scales for structural rearrangement of nanoparticles with the bulk gelation behavior. Our results show that the kinetics for local structural changes between particles and bulk gelation from UV exposure are strongly correlated.

  16. Large Volume Self-Organization of Polymer/Nanoparticle Hybrids with Millimeter Scale Grain Sizes using Brush Block Copolymers

    NASA Astrophysics Data System (ADS)

    Song, Dongpo; Watkins, James

    The lack of sufficient long-range order in self-assembled nanostructures is a bottleneck for many nanotechnology applications. In this work, we report that exceptionally large volume of highly ordered arrays (single grains) on the order of millimeters in scale can be rapidly created through a unique innate guiding mechanism of brush block copolymers (BBCPs). The grain volume is over 1 billion times larger relative to that of typical self-assembled linear BCPs (LBCPs). The use of strong interactions between nanoparticles (NPs) and BBCPs enables the high loadings of functional materials, up to 76 wt% (46 vol%) in the target domain, while maintaining excellent long-range order. Overall this work provides a simple route to precisely control the spatial orientation of functionalities at nanometer length scales over macroscopic volumes, thereby enabling the production of hybrid materials for many important applications.

  17. Simulation study on the structure of rod-coil-rod triblock copolymer and nanoparticle mixture within slit.

    PubMed

    Huang, Jian-Hua; Fan, Zhong-Xiang; Luo, Meng-Bo

    2013-11-28

    Self-assembly structures of rod-coil-rod ABA triblock copolymer and nanoparticle mixture within a slit are simulated by dissipative particle dynamics method. Results show that the structures are dependent on the rigidity of the rod block kθ, the interaction between the rod block and slit a(wA), the fraction of rod block f(A), and the slit height H. With an increase in kθ, we observe a transition from parallel lamellae to hexagonal cylinders. While with the increase in a(wA), the parallel lamellae at small kθ and hexagonal cylinders at large kθ change to perpendicular lamellae at large a(wA) close to a(As). At last, we present a phase diagram of structure with respect to f(A) and H at large kθ. PMID:24289376

  18. Synthesis and Characterization of Silicate Ester Prodrugs and Poly(ethylene glycol)-b-poly(lactic-co-glycolic acid) Block Copolymers for Formulation into Prodrug-Loaded Nanoparticles

    NASA Astrophysics Data System (ADS)

    Wohl, Adam Richard

    Fine control of the physical and chemical properties of customized materials is a field that is rapidly advancing. This is especially critical in pursuits to develop and optimize novel nanoparticle drug delivery. Specifically, I aim to apply chemistry concepts to test the hypothesis "Silicate ester prodrugs of paclitaxel, customized to have the proper hydrophobicity and hydrolytic lability, can be formulated with well-defined, biocompatible, amphiphilic block copolymers into nanoparticles that are effective drugs." Chapter 1 briefly describes the context and motivation of the scientific pursuits described in this thesis. In Chapter 2, a family of model silicate esters is synthesized, the hydrolysis rate of each compound is benchmarked, and trends are established based upon the steric bulk and leaving group ability of the silicate substituents. These trends are then applied to the synthesis of labile silicate ester prodrugs in Chapter 3. The bulk of this chapter focuses on the synthesis, hydrolysis, and cytotoxicity of prodrugs based on paclitaxel, a widely used chemotherapeutic agent. In Chapter 4, a new methodology for the synthesis of narrowly dispersed, "random" poly(lactic-co-glycolic acid) polymers by a constant infusion of the glycolide monomer is detailed. Using poly(ethylene glycol) as a macroinitiator, amphiphilic block copolymers were synthesized. Co-formulating a paclitaxel silicate and an amphiphilic block copolymer via flash nanoprecipitation led to highly prodrug-loaded, kinetically trapped nanoparticles. Studies to determine the structure, morphology, behavior, and efficacy of these nanoparticles are described in Chapter 5. Efforts to develop a general strategy for the selective end-functionalization of the polyether block of these amphiphilic block copolymers are discussed in Chapter 6. Examples of this strategy include functionalization of the polyether with an azide or a maleimide. Finally, Chapter 7 provides an outlook for future development of

  19. Synthesis of biocompatible poly(ɛ-caprolactone)- block-poly(propylene adipate) copolymers appropriate for drug nanoencapsulation in the form of core-shell nanoparticles

    PubMed Central

    Nanaki, Stavroula G; Pantopoulos, Kostas; Bikiaris, Dimitrios N

    2011-01-01

    Poly(propylene adipate)-block-poly(ɛ-caprolactone) copolymers were synthesized using a combination of polycondensation and ring-opening polymerization of ɛ-caprolactone in the presence of poly(propylene adipate). Gel permeation chromatography was used for molecular weight determination, whereas hydrogen-1 nuclear magnetic resonance and carbon-13 nuclear magnetic resonance spectroscopy were employed for copolymer characterization and composition evaluation. The copolymers were found to be block while their composition was similar to the feeding ratio. They formed semicrystalline structures, while only poly(ɛ-caprolactone) formed crystals, as shown by wide angle X-ray diffraction. Differential scanning calorimetry data suggest that the melting point and heat of fusion of copolymers decreased by increasing the poly(propylene adipate) amount. The synthesized polymers exhibited low cytotoxicity and were used to encapsulate desferrioxamine, an iron-chelating drug. The desferrioxamine nanoparticles were self-assembled into core shell structures, had mean particle size <250 nm, and the drug remained in crystalline form. Further studies revealed that the dissolution rate was mainly related to the melting temperature, as well as to the degree of crystallinity of copolymers. PMID:22162656

  20. Thermal annealing as an easy tool for the controlled arrangement of gold nanoparticles in block-copolymer thin films

    NASA Astrophysics Data System (ADS)

    Ledo-Suárez, Ana; Hoppe, Cristina Elena; Lazzari, Massimo; Lopez Quintela, M. Arturo; Zucchi, Ileana Alicia

    2013-06-01

    Thermal annealing was used for the bottom-up fabrication of morphologically controlled gold-block-copolymer (Au-BC) nanocomposites. Three different blends formed by polystyrene (PS) homopolymer and PS-coated gold nanoparticles (PSSH@Au) were used as modifiers of asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA): PS26/PS26SH@Au, PS75/PS75SH@Au and PS167/PS167SH@Au (where the subscripts refer to the number of styrene monomeric units). The results indicated that all three blends used as modifiers (PSn/PSnSH@Au) were successfully located in the PS phase during thermally induced BC self-assembly for a composition range from 5 to 43 wt% without macro-phase separation. The PSnSH@Au moiety experienced molecular desorption, nanocrystal core coalescence and partial molecular re-encapsulation processes during thermal annealing, leading to sphere-like gold NPs with a larger average size (without exceeding an interdomain distance). Ligand chain length regulated the degree of coalescence and re-encapsulation, defining ultimate core size. Furthermore, proper combination of chain length and composition enabled tuning of NP partitioning and arrangement on different length scales through thermally activated cooperative assembly processes. These results have not only significant impact for establishing thermal processing as a useful tool for the precise control of NP size and distribution, but also much broader implications for many nanoparticle-based technologies.

  1. Composite Polylactic-Methacrylic Acid Copolymer Nanoparticles for the Delivery of Methotrexate

    PubMed Central

    Sibeko, Bongani; Choonara, Yahya E.; du Toit, Lisa C.; Modi, Girish; Naidoo, Dinesh; Khan, Riaz A.; Kumar, Pradeep; Ndesendo, Valence M. K.; Iyuke, Sunny E.; Pillay, Viness

    2012-01-01

    The purpose of this study was to develop poly(lactic acid)-methacrylic acid copolymeric nanoparticles with the potential to serve as nanocarrier systems for methotrexate (MTX) used in the chemotherapy of primary central nervous system lymphoma (PCNSL). Nanoparticles were prepared by a double emulsion solvent evaporation technique employing a 3-Factor Box-Behnken experimental design strategy. Analysis of particle size, absolute zeta potential, polydispersity (Pdl), morphology, drug-loading capacity (DLC), structural transitions through FTIR spectroscopy, and drug release kinetics was undertaken. Molecular modelling elucidated the mechanisms of the experimental findings. Nanoparticles with particle sizes ranging from 211.0 to 378.3 nm and a recovery range of 36.8–86.2 mg (Pdl ≤ 0.5) were synthesized. DLC values were initially low (12 ± 0.5%) but were finally optimized to 98 ± 0.3%. FTIR studies elucidated the comixing of MTX within the nanoparticles. An initial burst release (50% of MTX released in 24 hours) was obtained which was followed by a prolonged release phase of MTX over 84 hours. SEM images revealed near-spherical nanoparticles, while TEM micrographs revealed the presence of MTX within the nanoparticles. Stable nanoparticles were formed as corroborated by the chemometric modelling studies undertaken. PMID:22919501

  2. Enhancement of Airway Gene Transfer by DNA Nanoparticles Using a pH-Responsive Block Copolymer of Polyethylene Glycol and Poly-L-lysine

    PubMed Central

    Boylan, Nicholas J.; Kim, Anthony J.; Suk, Jung Soo; Adstamongkonkul, Pichet; Simons, Brian W.; Lai, Samuel K.; Cooper, Mark J.; Hanes, Justin

    2011-01-01

    Highly compacted DNA nanoparticles, composed of single molecules of plasmid DNA compacted with block copolymers of polyethylene glycol and poly-L-lysine (PEG-CK30), have shown considerable promise in human gene therapy clinical trials in the nares, but may be less capable of transfecting cells that lack surface nucleolin. To address this potential shortcoming, we formulated pH-responsive DNA nanoparticles that mediate gene transfer via a nucleolin-independent pathway. Poly-L-histidine was inserted between PEG and poly-L-lysine to form a triblock copolymer system, PEG-CH12K18. Inclusion of poly-L-histidine increased the buffering capacity of PEG-CH12K18 to levels comparable with branched polyethyleneimine. PEG-CH12K18 compacted DNA into rod-shaped DNA nanoparticles with similar morphology and colloidal stability as PEG-CK30 DNA nanoparticles. PEG-CH12K18 DNA nanoparticles entered human bronchial epithelial cells (BEAS-2B) that lack surface nucleolin by a clathrin-dependent endocytic mechanism followed by endo-lysosomal processing. Despite trafficking through the degradative endo-lysosomal pathway, PEG-CH12K18 DNA nanoparticles improved the in vitro gene transfer by ~ 20-fold over PEG-CK30 DNA nanoparticles, and in vivo gene transfer to lung airways in BALB/c mice by ~ 3-fold, while maintaining a favorable toxicity profile. These results represent an important step toward the rational development of an efficient gene delivery platform for the lungs based on highly compacted DNA nanoparticles. PMID:22182747

  3. Enhancement of airway gene transfer by DNA nanoparticles using a pH-responsive block copolymer of polyethylene glycol and poly-L-lysine.

    PubMed

    Boylan, Nicholas J; Kim, Anthony J; Suk, Jung Soo; Adstamongkonkul, Pichet; Simons, Brian W; Lai, Samuel K; Cooper, Mark J; Hanes, Justin

    2012-03-01

    Highly compacted DNA nanoparticles, composed of single molecules of plasmid DNA compacted with block copolymers of polyethylene glycol and poly-L-lysine (PEG-CK(30)), have shown considerable promise in human gene therapy clinical trials in the nares, but may be less capable of transfecting cells that lack surface nucleolin. To address this potential shortcoming, we formulated pH-responsive DNA nanoparticles that mediate gene transfer via a nucleolin-independent pathway. Poly-L-histidine was inserted between PEG and poly-L-lysine to form a triblock copolymer system, PEG-CH(12)K(18). Inclusion of poly-L-histidine increased the buffering capacity of PEG-CH(12)K(18) to levels comparable with branched polyethyleneimine. PEG-CH(12)K(18) compacted DNA into rod-shaped DNA nanoparticles with similar morphology and colloidal stability as PEG-CK(30) DNA nanoparticles. PEG-CH(12)K(18) DNA nanoparticles entered human bronchial epithelial cells (BEAS-2B) that lack surface nucleolin by a clathrin-dependent endocytic mechanism followed by endo-lysosomal processing. Despite trafficking through the degradative endo-lysosomal pathway, PEG-CH(12)K(18) DNA nanoparticles improved the in vitro gene transfer by ~20-fold over PEG-CK(30) DNA nanoparticles, and in vivo gene transfer to lung airways in BALB/c mice by ~3-fold, while maintaining a favorable toxicity profile. These results represent an important step toward the rational development of an efficient gene delivery platform for the lungs based on highly compacted DNA nanoparticles. PMID:22182747

  4. Phase behavior of nanoparticle/diblock copolymer in a selective solvent.

    SciTech Connect

    Lo, C.-T.; Lee, B.; Winans, R. E.; Thiyagarajan, P.

    2007-01-01

    Solvents used for controlling the self-assembly of polymer nanocomposites have a strong influence on the order-disorder and order-order transition temperatures. We have investigated the phase behavior of complexes composed of poly(styrene-b-2-vinylpyridine) (PS-PVP) and thiol-terminated PS stabilized Au nanoparticles in toluene-d (a good solvent for PS) by using small-angle neutron scattering. We observe that the morphologies of the neat and nanoparticle-containing polymer solutions strongly depend on the concentration of nanoparticles and temperature. Comparison of the phase diagrams of the neat and nanoparticle-containing polymer solutions as a function of temperature clearly shows dramatic shifts in the order-disorder and order-order transition temperatures. This dramatic effect can be understood by a model wherein the added nanoparticles that sequester in the preferred PS domains increase the interfacial curvature, leading to the observed changes in the nanostructure of the complex. Some effects are similar to those of the selective solvent such as toluene on the nanostructure of PS-PVP. Knowledge gained from these studies on the effects of nanoparticle concentration and temperature on the phase behavior of the polymer nanocomposites will be valuable for tailoring the physical properties of novel nanocomposites.

  5. Directed Nanoparticle Assembly onto Random Copolymer Templates: Kinetics and Surface Considerations

    NASA Astrophysics Data System (ADS)

    McConnell, Marla; Yang, Shu; Composto, Russell

    2008-03-01

    Recent efforts have focused on the development of nanoparticle arrays with controlled spacing. In this study, poly(styrene-ran-acrylic acid) films were prepared by spin-casting poly(styrene-ran-t-butyl acrylate), followed by thermal deprotection. Silica nanoparticles (10-15 nm in diameter) coated with self-assembled monolayers (SAMs) of (3-aminopropyl)triethoxysilane were covalently attached to the PS-ran-PAA films with an EDC/NHS coupling reaction. To measure the kinetics of nanoparticle attachment, films of either 25 or 50 weight percent acrylic acid were reacted with nanoparticle suspensions from 0.005 to 0.1 weight percent for varying lengths of time. SEM imaging of the nanoparticle surfaces showed that the particles were well dispersed, and that particle coverage increased with increasing AA and nanoparticle concentration, and time. SAMs containing an acrylic acid moiety were used as a non-swelling control surface, and particle attachment to these surfaces follow different kinetics than those observed for the polymeric substrates. The swelling of the polymeric substrates under the reaction conditions was found to influence the observed coverage kinetics, so film swelling was monitored with environmental AFM.

  6. Self-aggregated nanoparticles based on amphiphilic poly(lactic acid)-grafted-chitosan copolymer for ocular delivery of amphotericin B

    PubMed Central

    Zhou, Wenjun; Wang, Yuanyuan; Jian, Jiuying; Song, Shengfang

    2013-01-01

    Background The purpose of this study was to develop a self-aggregated nanoparticulate vehicle using an amphiphilic poly(lactic acid)-grafted-chitosan (PLA-g-CS) copolymer and to evaluate its potential for ocular delivery of amphotericin B. Methods A PLA-g-CS copolymer was synthesized via a “protection-graft-deprotection” procedure and its structure was confirmed by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, and X-ray diffraction spectra. Amphotericin B-loaded nanoparticles based on PLA-g-CS (AmB/PLA-g-CS) were prepared by the dialysis method and characterized for particle size, zeta potential, and encapsulation efficiency. Studies of these AmB/PLA-g-CS nanoparticles, including their mucoadhesive strength, drug release properties, antifungal activity, ocular irritation, ocular pharmacokinetics, and corneal penetration were performed in vitro and in vivo. Results Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, and X-ray diffraction spectra showed that the PLA chains were successfully grafted onto chitosan molecules and that crystallization of chitosan was suppressed. The self-aggregated PLA-g-CS nanoparticles had a core-shell structure with an average particle size of approximately 200 nm and zeta potentials higher than 30 mV. Amphotericin B was incorporated into the hydrophobic core of the nanoparticles with high encapsulation efficiency. Sustained drug release from the nanoparticles was observed in vitro. The ocular irritation study showed no sign of irritation after instillation of the PLA-g-CS nanoparticles into rabbit eyes. The minimal inhibitory concentration of the AmB/PLA-g-CS nanoparticles showed antifungal activity similar to that of free amphotericin B against Candida albicans. The in vivo ocular pharmacokinetic study suggested that the PLA-g-CS nanoparticles have the advantage of prolonging residence time at the ocular surface. The corneal penetration study showed that the PLA-g-CS nanoparticles

  7. Needlelike and spherical polyelectrolyte complex nanoparticles of poly(l-lysine) and copolymers of maleic acid.

    PubMed

    Müller, M; Reihs, T; Ouyang, W

    2005-01-01

    We report on the bulk and surface properties of dispersions consisting of nonstoichiometric polyelectrolyte complex (PEC) nanoparticles. PEC nanoparticles were prepared by mixing poly(l-lysine) (PLL) or poly(diallyldimethylammonium chloride) (PDADMAC) with poly(maleic acid-co-alpha-methylstyrene) (PMA-MS) or poly(maleic acid-co-propylene) (PMA-P). The monomolar mixing ratio was n-/n+ = 0.6, and the concentration ranged from 1 to 6 mmol/L. Subsequent centrifugation enabled the separation of the excess polycation, resulting in a stable coacervate phase further used in the experiments. The bulk phase parameters turbidity and hydrodynamic radius (R(h)) of the PEC nanoparticles showed a linear dependence on the total polymer content independently of the mixed polyelectrolytes. This can be interpreted by the increased collision probability of the polyelectrolyte chains when the overlap concentration is approached or exceeded. Different morphologies of the cationic PEC nanoparticles, which were solution-cast onto Si supports, were obtained by atomic force microscopy (AFM). The combinations of PLL/PMA-MS and PDADMAC/PMA-MS revealed more or less hemispherical particle shapes, whereas that of PLL/PMA-P revealed an elongated needlelike particle shape. Circular dichroism and attenuated total reflection Fourier transform infrared (ATR-FTIR) measurements proved the alpha-helical conformation for the PEC PLL/PMA-P and the random coil conformation for the PEC PLL/PMA-MS. We conclude that stiff alpha-helical PLL induces anisotropic elongated PEC nanoparticles, whereas randomly coiled PLL forms isotropic spherical PEC nanoparticles. PMID:15620340

  8. Diblock-copolymer-mediated self-assembly of protein-stabilized iron oxide nanoparticle clusters for magnetic resonance imaging.

    PubMed

    Tähkä, Sari; Laiho, Ari; Kostiainen, Mauri A

    2014-03-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) can be used as efficient transverse relaxivity (T2 ) contrast agents in magnetic resonance imaging (MRI). Organizing small (D<10 nm) SPIONs into large assemblies can considerably enhance their relaxivity. However, this assembly process is difficult to control and can easily result in unwanted aggregation and precipitation, which might further lead to lower contrast agent performance. Herein, we present highly stable protein-polymer double-stabilized SPIONs for improving contrast in MRI. We used a cationic-neutral double hydrophilic poly(N-methyl-2-vinyl pyridinium iodide-block-poly(ethylene oxide) diblock copolymer (P2QVP-b-PEO) to mediate the self-assembly of protein-cage-encapsulated iron oxide (γ-Fe2 O3 ) nanoparticles (magnetoferritin) into stable PEO-coated clusters. This approach relies on electrostatic interactions between the cationic N-methyl-2-vinylpyridinium iodide block and magnetoferritin protein cage surface (pI≈4.5) to form a dense core, whereas the neutral ethylene oxide block provides a stabilizing biocompatible shell. Formation of the complexes was studied in aqueous solvent medium with dynamic light scattering (DLS) and cryogenic transmission electron microcopy (cryo-TEM). DLS results indicated that the hydrodynamic diameter (Dh ) of the clusters is approximately 200 nm, and cryo-TEM showed that the clusters have an anisotropic stringlike morphology. MRI studies showed that in the clusters the longitudinal relaxivity (r1 ) is decreased and the transverse relaxivity (r2 ) is increased relative to free magnetoferritin (MF), thus indicating that clusters can provide considerable contrast enhancement. PMID:24523066

  9. Thermosensitive hydrogel system assembled by PTX-loaded copolymer nanoparticles for sustained intraperitoneal chemotherapy of peritoneal carcinomatosis.

    PubMed

    Xu, Shuxin; Fan, Hongxia; Yin, Li; Zhang, Jianhua; Dong, Anjie; Deng, Liandong; Tang, Hua

    2016-07-01

    Intraperitoneal (IP) chemotherapy is a preferable treatment option for peritoneal carcinomatosis of malignancies by delivering chemotherapeutic drugs into the abdominal cavity. A persistent major challenge in IP chemotherapy is the need to provide effective drug concentration in the peritoneal cavity for an extended period of time. In the present work, the thermosensitive hydrogel system (PTX/PECT(gel)) assembled by PTX (paclitaxel)-loaded amphiphilic copolymer (PECT, poly (ε-caprolactone-co-1,4,8-trioxa [4.6]spiro-9-undecanone)-poly(ethylene glycol)-poly (ε-caprolactone-co-1,4,8-trioxa [4.6]spiro-9-undecanone)) nanoparticles was developed for sustained IP chemotherapy of peritoneal carcinomatosis model. Cytotoxicity assay indicated that PECT hydrogel was biocompatible with very low cytotoxicity and PTX/PECT(gel) had enhanced cytotoxicity than free PTX. In vivo toxicity study demonstrated the biocompatibility and biosafety of PECT hydrogel as an IP chemotherapy carrier. The fluorescence imaging method was employed to monitor the intraperitoneal degradation of PECT hydrogel by labeling PECT with rhodamine B. PECT hydrogel with the dose of 200μL showed about 8days' retention time and most of the injected hydrogel was located in the intestine. The anti-tumor efficacy study was carried out in mice bearing CT26 intraperitoneal ascites fluid as colorectal peritoneal carcinomatosis model. The result showed that intraperitoneal administration of PTX/PECT(gel) could effectively suppress growth and metastasis of CT26 peritoneal carcinomatosis in vivo, compared with Taxol® group. The pharmacokinetic studies demonstrated that PTX/PECT(gel) could improve the bioavailability of PTX by being formulated in PECT hydrogel. Overall, sustained drug concentration at peritoneal levels in combination with drug in the form of nanoparticle contributes to the enhanced anti-tumor efficacy. Thus, our results suggested that PTX/PECT(gel) may have great potential applications in IP

  10. Selective confinement of oleylamine capped Au nanoparticles in self-assembled PS-b-PEO diblock copolymer templates.

    PubMed

    Di Mauro, A Evelyn; Striccoli, Marinella; Depalo, Nicoletta; Fanizza, Elisabetta; Cano, Laida; Ingrosso, Chiara; Agostiano, Angela; Curri, M Lucia; Tercjak, Agnieszka

    2014-03-21

    Amphiphilic polystyrene-block-polyethylene oxide (PS-b-PEO) block copolymers (BCPs) have been demonstrated to be effective in directing organization of colloidal Au nanoparticles (NPs). Au NPs have been incorporated into the polymer and the different chemical affinity between the NP surface and the two blocks of the BCP has been used as a driving force of the assembling procedure. The morphology of the nanocomposites, prepared and fabricated as thin films, has been investigated by means of atomic force and scanning electron microscopies as a function of the NP content and BCP molecular weight. NPs have been effectively dispersed in PS-b-PEO hosts at any investigated content (up to 17 wt%) and a clear effect of the BCP properties on the final nanocomposite morphology has been highlighted. Finally, electrostatic force microscopy has demonstrated the conductive properties of the nanocomposite films, showing that the embedded Au NPs effectively convey their conductive properties to the film. The overall investigation has confirmed the selective confinement of the as-prepared surfactant-coated metal NPs in the PS block of PS-b-PEO, thus proposing a very simple and prompt assembling tool for nanopatterning, potentially suitable for optoelectronic, sensing and catalysis applications. PMID:24800269

  11. Multidentate block-copolymer-stabilized ultrasmall superparamagnetic iron oxide nanoparticles with enhanced colloidal stability for magnetic resonance imaging.

    PubMed

    Chan, Nicky; Laprise-Pelletier, Myriam; Chevallier, Pascale; Bianchi, Andrea; Fortin, Marc-André; Oh, Jung Kwon

    2014-06-01

    Ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) with diameters <5 nm hold great promise as T1-positive contrast agents for in vivo magnetic resonance imaging. However, control of the surface chemistry of USPIOs to ensure individual colloidal USPIOs with a ligand monolayer and to impart biocompatibility and enhanced colloidal stability is essential for successful clinical applications. Herein, an effective and versatile strategy enabling the development of aqueous colloidal USPIOs stabilized with well-defined multidentate block copolymers (MDBCs) is reported. The multifunctional MDBCs are designed to consist of an anchoring block possessing pendant carboxylates as multidentate anchoring groups strongly bound to USPIO surfaces and a hydrophilic block having pendant hydrophilic oligo(ethylene oxide) chains to confer water dispersibility and biocompatibility. The surface of USPIOs is saturated with multiple anchoring groups of MDBCs, thus exhibiting excellent long-term colloidal stability as well as enhanced colloidal stability at biologically relevant electrolyte, pH, and temperature conditions. Furthermore, relaxometric properties as well as in vitro and in vivo MR imaging results demonstrate that the MDBC-stabilized USPIO colloids hold great potential as an effective T1 contrast agent. PMID:24785001

  12. Arrangement of Maghemite Nanoparticles via Wet Chemical Self-Assembly in PS-b-PNIPAM Diblock Copolymer Films.

    PubMed

    Yao, Yuan; Metwalli, Ezzeldin; Su, Bo; Körstgens, Volker; Moseguí González, Daniel; Miasnikova, Anna; Laschewsky, Andre; Opel, Matthias; Santoro, Gonzalo; Roth, Stephan V; Müller-Buschbaum, Peter

    2015-06-17

    The structure and magnetic behavior of hybrid films composed of maghemite (γ-Fe2O3) nanoparticles (NPs) and an asymmetric diblock copolymer (DBC) polystyrene61-block-polyN-isopropylacrylamide115 are investigated. The NPs are coated with PS chains, which allow for a selective incorporation inside the PS domains at different NP concentrations. Upon incorporation of low amounts of NPs into the DBC thin films, the initial parallel (to film surface) cylinder morphology changes to a well ordered, perpendicularly oriented one. The characteristic domain distance of the DBC is increased due to the swelling of the PS domains with NPs. At higher NP concentrations, the excess NPs which can no longer be embedded in the PS domains, are accumulated at the film surface, and NP aggregates form. Irrespective of NP concentration, a superparamagnetic behavior of the metal oxide-DBC hybrid films is found. Such superparamagnetic properties make the established hybrid films interesting for high density magnetic storage media and thermoresponsive magnetic sensors. PMID:26001128

  13. Hydrogen bonding strength of diblock copolymers affects the self-assembled structures with octa-functionalized phenol POSS nanoparticles.

    PubMed

    Lu, Yi-Syuan; Yu, Chia-Yu; Lin, Yung-Chih; Kuo, Shiao-Wei

    2016-02-28

    In this study, the influence of the functional groups by the diblock copolymers of poly(styrene-b-4-vinylpyridine) (PS-b-P4VP), poly(styrene-b-2-vinylpyridine) (PS-b-P2VP), and poly(styrene-b-methyl methacrylate) (PS-b-PMMA) on their blends with octa-functionalized phenol polyhedral oligomeric silsesquioxane (OP-POSS) nanoparticles (NPs) was investigated. The relative hydrogen bonding strengths in these blends follow the order PS-b-P4VP/OP-POSS > PS-b-P2VP/OP-POSS > PS-b-PMMA/OP-POSS based on the Kwei equation from differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopic analyses. Small-angle X-ray scattering and transmission electron microscopic analyses show that the morphologies of the self-assembly structures are strongly dependent on the hydrogen bonding strength at relatively higher OP-POSS content. The PS-b-P4VP/OP-POSS hybrid complex system with the strongest hydrogen bonds shows the order-order transition from lamellae to cylinders and finally to body-centered cubic spheres upon increasing OP-POSS content. However, PS-b-P2VP/OP-POSS and PS-b-PMMA/OP-POSS hybrid complex systems, having relatively weaker hydrogen bonds, transformed from lamellae to cylinder structures at lower OP-POSS content (<50 wt%), but formed disordered structures at relatively high OP-POSS contents (>50 wt%). PMID:26781581

  14. Core-Corona Functionalization of Diblock Copolymer Micelles by Heterogeneous Metal Nanoparticles for Dual Modality in Chemical Reactions.

    PubMed

    Jo, Seong Ho; Kim, Hyun Woo; Song, Minkyung; Je, Nam Jin; Oh, Sung-Hoon; Chang, Byoung-Yong; Yoon, Jinhwan; Kim, Joo Hyun; Chung, Bonghoon; Yoo, Seong Il

    2015-08-26

    Nanoscale assemblies composed of different types of nanoparticles (NPs) can reveal interesting aspects about material properties beyond the functions of individual constituent NPs. This research direction may also represent current challenges in nanoscience toward practical applications. With respect to the assembling method, synthetic or biological nanostructures can be utilized to organize heterogeneous NPs in specific sites via chemical or physical interactions. However, those assembling methods often encounter uncontrollable particle aggregation or phase separation. In this study, we anticipated that the self-segregating properties of block copolymer micelles could be particularly useful for organizing heterogeneous NPs, because the presence of chemically distinct domains such as the core and the corona can facilitate the selective placement of constituent NPs in separate domains. Here, we simultaneously functionalized the core and the corona of micelles by Au NPs and Ag NPs, which exhibited plasmonic and catalytic functions, respectively. Our primary question is whether these plasmonic and catalytic functions can be combined in the assembled structures to engineer the kinetics of a model chemical reaction. To test this hypothesis, the catalytic reduction of 4-nitrophenol was selected to evaluate the collective properties of the micellar assemblies in a chemical reaction. PMID:26241213

  15. Preparation and optical properties of CdS nanoparticles dispersed in poly(2-(dimethylamino)ethyl methacrylate-co-acrylic acid) co-polymers

    NASA Astrophysics Data System (ADS)

    Trandafilović, L. V.; Djoković, V.; Bibić, N.; Georges, M. K.; Radhakrishnan, T.

    2008-03-01

    CdS/poly(2-(dimethylamino)ethyl methacrylate-co-acrylic acid) nanocomposites were prepared and characterized using structural, optical and thermal methods. Co-polymers used as the matrices were synthesized by radical polymerization of the co-monomers in different mol ratios (1:1, 2:1 and 1:2, DMAEMA:acrylic acid). The presence of the nanostructured CdS was confirmed by TEM analysis as well as by the shift of the onset of the optical absorption towards lower wavelengths. XRD spectra showed the cubic crystal phase of the obtained CdS nanoparticles. TGA measurements revealed improved thermal stability of the nanocomposite with respect to pure co-polymer matrix.

  16. Magnetic studies of iron oxide nanoparticles coated with oleic acid and Pluronic® block copolymer

    NASA Astrophysics Data System (ADS)

    Morales, M. A.; Jain, Tapan Kumar; Labhasetwar, V.; Leslie-Pelecky, D. L.

    2005-05-01

    We have prepared and studied iron-oxide nanoparticles coated with oleic acid (OA) and Pluronic® polymer. The mean diameter of the iron-oxide nanoparticles was 9.3(±)0.8nm. Saturation magnetization values measured at 10K varied from 66.1(±0.7)emu/gto98.7(±0.5)emu/g. At 300K the loops showed negligible coercive field. The peaks in zero-field-cooled susceptibility decreased from 280to168K with increasing OA concentration up to 10.6wt%, and remained nearly constant for higher concentrations. This suggests that incomplete coverage of the OA allows small, interacting agglomerates to form.

  17. Structural effects on the biodistribution and positron emission tomography (PET) imaging of well-defined (64)Cu-labeled nanoparticles comprised of amphiphilic block graft copolymers.

    PubMed

    Pressly, Eric D; Rossin, Raffaella; Hagooly, Aviv; Fukukawa, Ken-Ichi; Messmore, Benjamin W; Welch, Michael J; Wooley, Karen L; Lamm, Matthew S; Hule, Rohan A; Pochan, Darrin J; Hawker, Craig J

    2007-10-01

    The synthesis of poly(methyl methacrylate-co-methacryloxysuccinimide-graft-poly(ethylene glycol)) (PMMA-co-PMASI-g-PEG) via living free radical polymerization provides a convenient route to well-defined amphiphilic graft copolymers having a controllable number of reactive functional groups, variable length PEG grafts, and low polydispersity. These copolymers were shown to form PMMA-core/PEG-shell nanoparticles upon hydrophobic collapse in water, with the hydrodynamic size being defined by the molecular weight of the backbone and the PEG grafts. Functionalization of these polymeric nanoparticles with a 1,4,7,10-tetraazacyclododecanetetraacetic acid (DOTA) ligand capable of chelating radioactive 64Cu nuclei enabled the biodistribution and in vivo positron emission tomography of these materials to be studied and directly correlated to the initial structure. Results indicate that nanoparticles with increasing PEG chain lengths show increased blood circulation and low accumulation in excretory organs, suggesting the possible use of these materials as stealth carriers for medical imaging and systemic administration. PMID:17880180

  18. Loading of Silica Nanoparticles in Block Copolymer Vesicles during Polymerization-Induced Self-Assembly: Encapsulation Efficiency and Thermally Triggered Release

    PubMed Central

    2015-01-01

    Poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) diblock copolymer vesicles can be prepared in the form of concentrated aqueous dispersions via polymerization-induced self-assembly (PISA). In the present study, these syntheses are conducted in the presence of varying amounts of silica nanoparticles of approximately 18 nm diameter. This approach leads to encapsulation of up to hundreds of silica nanoparticles per vesicle. Silica has high electron contrast compared to the copolymer which facilitates TEM analysis, and its thermal stability enables quantification of the loading efficiency via thermogravimetric analysis. Encapsulation efficiencies can be calculated using disk centrifuge photosedimentometry, since the vesicle density increases at higher silica loadings while the mean vesicle diameter remains essentially unchanged. Small angle X-ray scattering (SAXS) is used to confirm silica encapsulation, since a structure factor is observed at q ≈ 0.25 nm–1. A new two-population model provides satisfactory data fits to the SAXS patterns and allows the mean silica volume fraction within the vesicles to be determined. Finally, the thermoresponsive nature of the diblock copolymer vesicles enables thermally triggered release of the encapsulated silica nanoparticles simply by cooling to 0–10 °C, which induces a morphological transition. These silica-loaded vesicles constitute a useful model system for understanding the encapsulation of globular proteins, enzymes, or antibodies for potential biomedical applications. They may also serve as an active payload for self-healing hydrogels or repair of biological tissue. Finally, we also encapsulate a model globular protein, bovine serum albumin, and calculate its loading efficiency using fluorescence spectroscopy. PMID:26600089

  19. Loading of Silica Nanoparticles in Block Copolymer Vesicles during Polymerization-Induced Self-Assembly: Encapsulation Efficiency and Thermally Triggered Release.

    PubMed

    Mable, Charlotte J; Gibson, Rebecca R; Prevost, Sylvain; McKenzie, Beulah E; Mykhaylyk, Oleksandr O; Armes, Steven P

    2015-12-30

    Poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) diblock copolymer vesicles can be prepared in the form of concentrated aqueous dispersions via polymerization-induced self-assembly (PISA). In the present study, these syntheses are conducted in the presence of varying amounts of silica nanoparticles of approximately 18 nm diameter. This approach leads to encapsulation of up to hundreds of silica nanoparticles per vesicle. Silica has high electron contrast compared to the copolymer which facilitates TEM analysis, and its thermal stability enables quantification of the loading efficiency via thermogravimetric analysis. Encapsulation efficiencies can be calculated using disk centrifuge photosedimentometry, since the vesicle density increases at higher silica loadings while the mean vesicle diameter remains essentially unchanged. Small angle X-ray scattering (SAXS) is used to confirm silica encapsulation, since a structure factor is observed at q ≈ 0.25 nm(-1). A new two-population model provides satisfactory data fits to the SAXS patterns and allows the mean silica volume fraction within the vesicles to be determined. Finally, the thermoresponsive nature of the diblock copolymer vesicles enables thermally triggered release of the encapsulated silica nanoparticles simply by cooling to 0-10 °C, which induces a morphological transition. These silica-loaded vesicles constitute a useful model system for understanding the encapsulation of globular proteins, enzymes, or antibodies for potential biomedical applications. They may also serve as an active payload for self-healing hydrogels or repair of biological tissue. Finally, we also encapsulate a model globular protein, bovine serum albumin, and calculate its loading efficiency using fluorescence spectroscopy. PMID:26600089

  20. Hybrid micellar hydrogels of a thermosensitive ABA triblock copolymer and hairy nanoparticles: effect of spatial location of hairy nanoparticles on gel properties.

    PubMed

    Hu, Bin; Henn, Daniel M; Wright, Roger A E; Zhao, Bin

    2014-09-23

    This article reports a method for control of spatial location of nanoparticles (NPs) in hybrid micellar hydrogels of a thermosensitive ABA triblock copolymer and polymer brush-grafted NPs (hairy NPs), either inside or outside the core of micelles, and the study of the effect of different locations of NPs on gel properties. Two batches of thermosensitive polymer brush-grafted, 17 nm silica NPs with different lower critical solution temperatures (LCSTs) and a thermosensitive ABA triblock copolymer composed of a poly(ethylene oxide) central block and thermosensitive outer blocks (ABA-D) were synthesized. The different locations of NPs were achieved by controlling the LCST of hairy NPs (LCST(NP)) relative to that of the thermosensitive outer blocks of ABA-D (LCST(ABA)). When the LCST(NP) and LCST(ABA) were similar, the NPs resided in the core of micelles upon heating from below the LCST(NP) and LCST(ABA). When the LCST(NP) was significantly higher, the NPs were located outside the core of micelles as confirmed by fluorescent resonance energy transfer. The effects of different locations of hairy NPs and NP-to-polymer mass ratio on properties of hybrid micellar hydrogels formed from aqueous solutions of ABA-D with a concentration of 10 wt % and various amounts of hairy NPs were studied by rheological measurements. The sol-gel transition temperature (T(sol-gel)) and dynamic storage modulus G' of the gels with NPs inside the core of micelles did not change much with increasing the NP-to-polymer mass ratio. In contrast, the T(sol-gel) of gels with NPs in the interstitial space among micelles increased slightly and the G' decreased significantly with the increase of the NP-to-polymer ratio. The hairy NPs in the interstitial space appeared to affect the formation of polymer networks and increase the fraction of polymer loops, resulting in a lower density of bridging chains and thus a lower G'. In addition, for gels with NPs in the interstitial space, a noticeable increase in

  1. Development and performance evaluation of novel nanoparticles of a grafted copolymer loaded with curcumin.

    PubMed

    Mutalik, Srinivas; Suthar, Neelam A; Managuli, Renuka S; Shetty, Pallavi K; Avadhani, Kiran; Kalthur, Guruprasad; Kulkarni, Raghavendra V; Thomas, Ranjeny

    2016-05-01

    Inflammatory bowel disease (IBD) is an inflammatory condition with mucosal ulceration, edema and hemorrhage of gastrointestinal tract. Curcumin has been shown to mitigate colitis in animal models. However, its usefulness is reduced due to poor pharmacokinetic behavior and low oral bioavailability. To address this, novel pH-sensitive hydrolyzed polyacrylamide-grafted-xanthan gum (PAAm-g-XG) nanoparticles (NPs) loaded with curcumin were prepared for colonic delivery. Optimized nanoparticles (CN20) were spherical, with an average size of 425 nm. A negligible amount of curcumin (≈8%) was released from CN20 NPs in pH 1.2 and 4.5 solutions. When the pH was increased to 7.2, curcumin release was comparatively faster than that observed with pH 1.2 and 4.5 collectively. In pH 6.8 solution, excellent release of curcumin was observed. Highest curcumin release was observed when rat caecal contents were incorporated in pH 6.8 solution, indicating microflora-dependent drug release property of NPs. In acetic acid-induced IBD in rats, curcumin NPs reduced myeloperoxidase and nitrite levels, prevented weight loss and attenuated colonic inflammation. Curcumin was better absorbed systemically in nanoparticulate form with increased Cmax (∼3 fold) and AUC (∼2.5 fold) than when delivered as free curcumin. We demonstrate successful development of grafted co-polymeric NPs containing drug suitable for colon targeting. PMID:26851203

  2. Polyelectrolyte induced formation of silver nanoparticles in copolymer hydrogel and their application as catalyst

    SciTech Connect

    He, Yongqiang; Huang, Guanbo; Pan, Zeng; Liu, Yue; Gong, Qiaojuan; Yao, Chenzhong; Gao, Jianping

    2015-10-15

    Highlights: • A simple route for the in situ preparation of Ag nanoparticles has been developed. • The Ag loaded hydrogel showed catalytic activity for reduction of 4-nitrophenol. • The catalyst can be recovered by simple separation and showed good recyclability. - Abstract: A simple route for the in situ preparation of catalytically active Ag nanoparticles (NPs) in hydrogel networks has been developed. The electronegativity of the amide and carboxyl groups on the poly(acrylamide-co-acryl acid) chains caused strong binding of the Ag{sup +} ions which made the ions distribute uniformly inside the hydrogels. When the Ag{sup +} loaded hydrogels were immersed in NaBH{sub 4} solution, the Ag{sup +} ions on the polymer networks were reduced to Ag NPs. The resultant hydrogel showed good catalytic activity for the reduction of a common organic pollutant, 4-nitrophenol, with sodium borohydride. A kinetic study of the catalytic reaction was carried out and a possible reason for the decline of the catalytic performance with reuse is proposed.

  3. Co-delivery of cisplatin and paclitaxel by folic acid conjugated amphiphilic PEG-PLGA copolymer nanoparticles for the treatment of non-small lung cancer

    PubMed Central

    He, Zelai; Huang, Jingwen; Xu, Yuanyuan; Zhang, Xiangyu; Teng, Yanwei; Huang, Can; Wu, Yufeng; Zhang, Xi; Zhang, Huijun; Sun, Wenjie

    2015-01-01

    An amphiphilic copolymer, folic acid (FA) modified poly(ethylene glycol)-poly(lactic-co-glycolic acid) (FA-PEG-PLGA) was prepared and explored as a nanometer carrier for the co-delivery of cisplatin (cis-diaminodichloroplatinum, CDDP) and paclitaxel (PTX). CDDP and PTX were encapsulated inside the hydrophobic inner core and chelated to the middle shell, respectively. PEG provided the outer corona for prolonged circulation. An in vitro release profile of the CDDP + PTX-encapsulated nanoparticles revealed that the PTX chelation cross-link prevented an initial burst release of CDDP. After an incubation period of 24 hours, the CDDP+PTX-encapsulated nanoparticles exhibited a highly synergistic effect for the inhibition of A549 (FA receptor negative) and M109 (FA receptor positive) lung cancer cell line proliferation. Pharmacokinetic experiment and distribution research shows that nanoparticles have longer circulation time in the blood and can prolong the treatment times of chemotherapeutic drugs. For the in vivo treatment of A549 cells xeno-graft lung tumor, the CDDP+PTX-encapsulated nanoparticles displayed an obvious tumor inhibiting effect with an 89.96% tumor suppression rate (TSR). This TSR was significantly higher than that of free chemotherapy drug combination or nanoparticles with a single drug. For M109 cells xeno-graft tumor, the TSR was 95.03%. In vitro and in vivo experiments have all shown that the CDDP+PTX-encapsulated nanoparticles have better targeting and antitumor effects in M109 cells than CDDP+PTX-loaded PEG-PLGA nanoparticles (p < 0.05). In addition, more importantly, the enhanced anti-tumor efficacy of the CDDP+PTX-encapsulated nanoparticles came with reduced side-effects. No obvious body weight loss or functional changes occurred within blood components, liver, or kidneys during the treatment of A549 and M109 tumor-bearing mice with the CDDP+PTX-encapsulated nanoparticles. Thus, the FA modified amphiphilic copolymer-based combination of CDDP and

  4. Influence of magnetic nanoparticle size on the particle dispersion and phase separation in an ABA triblock copolymer.

    PubMed

    Wu, Jinrong; Li, Hui; Wu, Siduo; Huang, Guangsu; Xing, Wang; Tang, Maozhu; Fu, Qiang

    2014-02-27

    Oleic acid modified iron oxide nanoparticles (IONs) with different sizes were synthesized and mixed with styrene-butadiene-styrene block copolymer (SBS) with a lamellar structure. The octadecene segments on the oleic acid molecules have chemical affinity with the polybutadiene (PB) blocks, which makes IONs tend to be selectively confined in the microphase-separated PB domains. However, the dispersion state strongly depends on the ratio of the particle diameter (d) to the lamellar thickness (l) of the PB domains, which further changes the phase separation of SBS. When d/l ∼0.5, most of IONs are concentrated in the middle of the PB layers at low particle loading. Upon increasing the particle loading, part of IONs contact each other to form long strings due to their strong magnetic interactions. Away from the strings, IONs are either selectively dispersed in the middle and at the interfaces of the PB domains, or randomly distributed at some regions in which the phase separation of SBS is suppressed. The phase separation of SBS transforms from the lamellar structure to a cylinder structure when the IONs loading is higher than 16.7 wt %. As d is comparable to l, IONs aggregate to form clusters of 100 to 300 nm in size, but within the clusters IONs are still selectively dispersed in the PB domains instead of forming macroscopic phase separation. It is interpreted in terms of the relatively small conformational entropy of the middle blocks of SBS; thus, incorporation of nanoparticles does not lead to much loss of conformational entropy. Although incorporation of IONs with d/l ∼1 significantly increases the interfacial curvature and roughness, it has less influence on the phase separation structure of SBS due to the inhomogeneous dispersion. When d is larger than l, IONs are macroscopically separated from the SBS matrix to form clusters of hundreds of nanometers to several micrometers. More interestingly, the phase separation of SBS transforms from the lamellar

  5. Doped copolymer of polyanthranilic acid and o-aminophenol (AA-co-OAP): Synthesis, spectral characterization and the use of the doped copolymer as precursor of α-Fe2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Hosny, Nasser Mohammed; Nowesser, Nourhan; Al-Hussaini, A. S.; Zoromba, Mohamed Shafick

    2016-02-01

    The copolymer of anthranilic acid and o-aminophenol (AA-co-OAP) was synthesized and characterized by IR, UV-Vis. and thermal analyses (TGA). Linear chain mode was suggested for the pure (AA-co-OAP). The effect of inclusion of MnCl2, CoCl2, NiCl2, CuCl2 and FeCl3 on the spectral, thermal and optical properties of AA-co-OAP has been studied. Octahedral stereochemistry was suggested for Fe, Mn and Ni doped AA-co-OAP, while tetrahedral and square-planar geometries were suggested for Co and Cu doped AA-co-OAP, respectively. Fe doped AA-co-OAP has been used as a precursor for α-Fe2O3 nanoparticles by thermal decomposition route at 800 °C. The obtained hematite has been characterized by XRD and TEM. The average size of the prepared nanoparticles was estimated as 34 nm. The optical band gap of the synthesized hematite nanoparticles was measured and compared with the bulk.

  6. pH-induced vesicle-to-micelle transition in amphiphilic diblock copolymer: investigation by energy transfer between in situ formed polymer embedded gold nanoparticles and fluorescent dye.

    PubMed

    Maiti, Chiranjit; Banerjee, Rakesh; Maiti, Saikat; Dhara, Dibakar

    2015-01-01

    The ability to regulate the formation of nanostructures through self-assembly of amphiphilic block copolymers is of immense significance in the field of biology and medicine. In this work, a new block copolymer synthesized by using reversible addition-fragmentation chain transfer (RAFT) polymerization technique from poly(ethylene glycol) monomethyl ether acrylate (PEGMA) and Boc-l-tryptophan acryloyloxyethyl ester (Boc-l-trp-HEA) was found to spontaneously form pH-responsive water-soluble nanostructures after removal of the Boc group. While polymer vesicles or polymerosomes were formed at physiological pH, the micelles were formed at acidic pH (< 5.2), and this facilitated a pH-induced reversible vesicle-to-micelle transition. Formation of these nanostructures was confirmed by different characterization techniques, viz. transmission electron microscopy, dynamic light scattering, and steady-state fluorescence measurements. Further, these vesicles were successfully utilized to reduce HAuCl4 and stabilize the resulting gold nanoparticles (AuNPs). These AuNPs, confined within the hydrophobic shell of the vesicles, could participate in energy transfer process with fluorescent dye molecules encapsulated in the core of the vesicles, thus forming a nanometal surface energy transfer (NSET) pair. Subsequently, following the efficiency of energy transfer between this pair, it was possible to monitor the process of transition from vesicles to micelles. Thus, in this work, we have successfully demonstrated that NSET can be used to follow the transition between nanostructures formed by amphiphilic block copolymers. PMID:25494810

  7. Improved anti-glioblastoma efficacy by IL-13Rα2 mediated copolymer nanoparticles loaded with paclitaxel

    PubMed Central

    Wang, Baoyan; Lv, Lingyan; Wang, Zhi; Jiang, Yan; Lv, Wei; Liu, Xin; Wang, Zhongyuan; Zhao, Yue; Xin, Hongliang; Xu, Qunwei

    2015-01-01

    Glioma presents one of the most malignant brain tumors, and the therapeutic effect is often limited due to the existence of brain tumor barrier. Based on interleukin-13 receptor α2 (IL-13Rα2) over-expression on glioma cell, it was demonstrated to be a potential receptor for glioma targeting. In this study, Pep-1-conjugated PEGylated nanoparticles loaded with paclitaxel (Pep-NP-PTX) were developed as a targeting drug delivery system for glioma treatment. The Pep-NP-PTX presented satisfactory size of 95.78 nm with narrow size distribution. Compared with NP-PTX, Pep-NP-PTX exhibited significantly enhanced cellular uptake in C6 cells (p < 0.001). The in vitro anti-proliferation evaluation showed that the IC50 were 146 ng/ml and 349 ng/ml of Pep-NP-PTX and NP-PTX, respectively. The in vivo fluorescent image results indicated that Pep-NP had higher specificity and efficiency in intracranial tumor accumulation. Following intravenous administration, Pep-NP-PTX could enhance the distribution of PTX in vivo glioma section, 1.98, 1.91 and 1.53-fold over that of NP-PTX group after 0.5, 1 and 4 h, respectively. Pep-NP-PTX could improve the anti-glioma efficacy with a median survival time of 32 days, which was significantly longer than that of PTX-NP (23 days) and Taxol® (22 days). In conclusion, Pep-NP-PTX is a potential targeting drug delivery system for glioma treatment. PMID:26567528

  8. Direct hierarchical assembly of nanoparticles

    DOEpatents

    Xu, Ting; Zhao, Yue; Thorkelsson, Kari

    2014-07-22

    The present invention provides hierarchical assemblies of a block copolymer, a bifunctional linking compound and a nanoparticle. The block copolymers form one micro-domain and the nanoparticles another micro-domain.

  9. The effect of the processing and formulation parameters on the size of nanoparticles based on block copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide) with and without hydrolytically sensitive groups.

    PubMed

    Neradovic, D; Soga, O; Van Nostrum, C F; Hennink, W E

    2004-05-01

    Block copolymers of poly(ethylene glycol) (PEG) as a hydrophilic block and N-isopropylacrylamide (PNIPAAm) or poly (NIPAAm-co-N-(2-hydroxypropyl) methacrylamide-dilactate) (poly(NIPAAm-co-HPMAm-dilactate)) as a thermosensitive block, are able to self-assemble in water into nanoparticles above the cloud point (CP) of the thermosensitive block. The influence of processing and the formulation parameters on the size of the nanoparticles was studied using dynamic light scattering. PNIPAAm-b-PEG 2000 polymers were not suitable for the formation of small and stable particles. Block copolymers with PEG 5000 and 10000 formed relatively small and stable particles in aqueous solutions at temperatures above the CP of the thermosensitive block. Their size decreased with increasing molecular weight of the thermosensitive block, decreasing polymer concentration and using water instead of phosphate buffered saline as solvent. Extrusion and ultrasonication were inefficient methods to size down the polymeric nanoparticles. The heating rate of the polymer solutions was a dominant factor for the size of the nanoparticles. When an aqueous polymer solution was slowly heated through the CP, rather large particles (> or = 200 nm) were formed. Regardless the polymer composition, small nanoparticles (50-70 nm) with a narrow size distribution were formed, when a small volume of an aqueous polymer solution below the CP was added to a large volume of heated water. In this way the thermosensitive block copolymers rapidly pass their CP ('heat shock' procedure), resulting in small and stable nanoparticles. PMID:14741606

  10. Reversible sol-gel transitions of aqueous dispersions of silica nanoparticles grafted with diblock copolymer brushes composed of a thermosensitive inner block and a charged outer block.

    PubMed

    Wright, Roger A E; Hu, Bin; Henn, Daniel M; Zhao, Bin

    2015-09-14

    We report in this article that aqueous dispersions of thermosensitive diblock copolymer brush-grafted 17 nm silica nanoparticles (hairy NPs) can undergo in situ, reversible sol-gel transitions in response to temperature changes. The brushes consisted of a thermosensitive poly(methoxydi(ethylene glycol) methacrylate) (PDEGMMA) inner block and a charge-carrying, poly(DEGMMA-co-2-(methacryloyloxy)ethyltrimethylammonium iodide) outer block, which were prepared by a one-pot, surface-initiated atom transfer radical polymerization and subsequent quaternization of tertiary amine moieties in the second block with iodomethane. Above a critical concentration, the aqueous dispersion of hairy NPs with an appropriate block copolymer composition exhibited a reversible transition from a free flowing liquid to a free standing hydrogel upon cooling from elevated temperatures, which was driven by the lower critical solution temperature transition of the thermosensitive inner block of hairy NPs as confirmed by dynamic light scattering study. At the same concentration of hairy NPs, the sol-gel transition temperature was higher when the highly hydrated, charged outer block was longer. The transition temperature decreased with decreasing the concentration of hairy NPs in the dispersion; reversible gelation was achieved with a concentration of hairy NPs in water as low as 5.5 wt%. Interestingly, the LCST transition of the inner thermosensitive PDEGMMA block disappeared and no sol-gel transition was observed in the studied temperature range when the charged outer block was sufficiently long. PMID:26223449

  11. Biodegradable Nanoparticles of mPEG-PLGA-PLL Triblock Copolymers as Novel Non-Viral Vectors for Improving siRNA Delivery and Gene Silencing

    PubMed Central

    Du, Jing; Sun, Ying; Shi, Qiu-Sheng; Liu, Pei-Feng; Zhu, Ming-Jie; Wang, Chun-Hui; Du, Lian-Fang; Duan, You-Rong

    2012-01-01

    Degradation of mRNA by RNA interference is one of the most powerful and specific mechanisms for gene silencing. However, insufficient cellular uptake and poor stability have limited its usefulness. Here, we report efficient delivery of siRNA via the use of biodegradable nanoparticles (NPs) made from monomethoxypoly(ethylene glycol)-poly(lactic-co-glycolic acid)-poly-l-lysine (mPEG-PLGA-PLL) triblock copolymers. Various physicochemical properties of mPEG-PLGA-PLL NPs, including morphology, size, surface charge, siRNA encapsulation efficiency, and in vitro release profile of siRNA from NPs, were characterized by scanning electron microscope, particle size and zeta potential analyzer, and high performance liquid chromatography. The levels of siRNA uptake and targeted gene inhibition were detected in human lung cancer SPC-A1-GFP cells stably expressing green fluorescent protein. Examination of the cultured SPC-A1-GFP cells with fluorescent microscope and flow cytometry showed NPs loading Cy3-labeled siRNA had much higher intracellular siRNA delivery efficiencies than siRNA alone and Lipofectamine-siRNA complexes. The gene silencing efficiency of mPEG-PLGA-PLL NPs was higher than that of commercially available transfecting agent Lipofectamine while showing no cytotoxicity. Thus, the current study demonstrates that biodegradable NPs of mPEG-PLGA-PLL triblock copolymers can be potentially applied as novel non-viral vectors for improving siRNA delivery and gene silencing. PMID:22312268

  12. Gas phase infrared multiple photon dissociation spectra of positively charged sodium bis(2-ethylhexyl)sulfosuccinate reverse micelle-like aggregates.

    PubMed

    Giorgi, Gianluca; Ceraulo, Leopoldo; Berden, Giel; Oomens, Jos; Liveri, Vincenzo Turco

    2011-03-17

    The capability of infrared multiple photon dissociation (IRMPD) spectroscopy to gain structural information on surfactant-based supramolecular aggregates has been exploited to elucidate intermolecular interactions and local organization of positively charged sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) aggregates in the gas phase. A detailed analysis of the stretching modes of the AOTNa CO and SO(3)(-) head groups allows one to directly probe their interactions with sodium counterions and to gain insight in their organization within the aggregate. Similarities and differences of the IRMPD spectra as compared to the infrared absorption spectrum of micellized AOTNa in CCl(4) have been analyzed. They strongly suggest a reverse micelle-like organization of AOTNa charged aggregates in the gas phase. Apart from low-abundance fragmentation channels of the AOTNa (molecule) itself, the main dissociation pathway of singly charged surfactant aggregates is the loss of neutral surfactant molecules, while doubly charged aggregates dissociate preferentially by charge separation forming singly charged species. In both cases, decomposition leads to the formation of the most energetically stable charged fragments. PMID:21341816

  13. A novel paclitaxel-loaded poly(d,l-lactide-co-glycolide)-Tween 80 copolymer nanoparticle overcoming multidrug resistance for lung cancer treatment

    PubMed Central

    Yuan, Xun; Ji, Wenxiang; Chen, Si; Bao, Yuling; Tan, Songwei; Lu, Shun; Wu, Kongming; Chu, Qian

    2016-01-01

    Drug resistance has become a main obstacle for the effective treatment of lung cancer. To address this problem, a novel biocompatible nanoscale package, poly(d,l-lactide-co-glycolide)-Tween 80, was designed and synthesized to overcome paclitaxel (PTX) resistance in a PTX-resistant human lung cancer cell line. The poly(d,l-lactide-co-glycolide) (PLGA)-Tween 80 nanoparticles (NPs) could efficiently load PTX and release the drug gradually. There was an increased level of uptake of PLGA-Tween 80 in PTX-resistant lung cancer cell line A549/T, which achieved a significantly higher level of cytotoxicity than both PLGA NP formulation and Taxol®. The in vivo antitumor efficacy also showed that PLGA-Tween 80 NP was more effective than Taxol®, indicating that PLGA-Tween 80 copolymer was a promising carrier for PTX in resistant lung cancer. PMID:27307727

  14. Amphiphilic poly{[α-maleic anhydride-ω-methoxy-poly(ethylene glycol)]-co-(ethyl cyanoacrylate)} graft copolymer nanoparticles as carriers for transdermal drug delivery

    PubMed Central

    Xing, Jinfeng; Deng, Liandong; Li, Jun; Dong, Anjie

    2009-01-01

    In this study, the transdermal drug delivery properties of D,L-tetrahydropalmatine (THP)-loaded amphiphilic poly{[α-maleic anhydride-ω-methoxy-poly(ethylene glycol)]-co-(ethyl cyanoacrylate)} (PEGECA) graft copolymer nanoparticles (PEGECAT NPs) were evaluated by skin penetration experiments in vitro. The transdermal permeation experiments in vitro were carried out in Franz diffusion cells using THP-loaded PEGECAT NPs as the donor system. Transmission electron microscopy and Fourier transform infrared spectroscopy were used to characterize the receptor fluid. The results indicate that the THP-loaded PEGECAT NPs are able to penetrate the rat skin. Fluorescent microscopy measurements demonstrate that THP-loaded PEGECAT NPs can penetrate the skin not only via appendage routes but also via epidermal routes. This nanotechnology has potential application in transdermal drug delivery. PMID:19918369

  15. Arylenesiloxane copolymers

    NASA Technical Reports Server (NTRS)

    Breed, L. W.; Elliott, R. L.

    1967-01-01

    Arylenesiloxane copolymers with regularly ordered structures were discovered during efforts to develop organosilicon polymers. Arylenesilane and siloxane monomers were both synthesized in these experiments.

  16. Physiologically Based Pharmacokinetic Modeling of Fluorescently Labeled Block Copolymer Nanoparticles for Controlled Drug Delivery in Leukemia Therapy.

    PubMed

    Gilkey, M J; Krishnan, V; Scheetz, L; Jia, X; Rajasekaran, A K; Dhurjati, P S

    2015-03-01

    A physiologically based pharmacokinetic (PBPK) model was developed that describes the concentration and biodistribution of fluorescently labeled nanoparticles in mice used for the controlled delivery of dexamethasone in acute lymphoblastic leukemia (ALL) therapy. The simulated data showed initial spikes in nanoparticle concentration in the liver, spleen, and kidneys, whereas concentration in plasma decreased rapidly. These simulation results were consistent with previously published in vivo data. At shorter time scales, the simulated data predicted decrease of nanoparticles from plasma with concomitant increase in the liver, spleen, and kidneys before decaying at longer timepoints. Interestingly, the simulated data predicted an unaccounted accumulation of about 50% of the injected dose of nanoparticles. Incorporation of an additional compartment into the model justified the presence of unaccounted nanoparticles in this compartment. Our results suggest that the proposed PBPK model can be an excellent tool for prediction of optimal dose of nanoparticle-encapsulated drugs for cancer treatment. PMID:26225236

  17. Physiologically Based Pharmacokinetic Modeling of Fluorescently Labeled Block Copolymer Nanoparticles for Controlled Drug Delivery in Leukemia Therapy

    PubMed Central

    Gilkey, MJ; Krishnan, V; Scheetz, L; Jia, X; Rajasekaran, AK; Dhurjati, PS

    2015-01-01

    A physiologically based pharmacokinetic (PBPK) model was developed that describes the concentration and biodistribution of fluorescently labeled nanoparticles in mice used for the controlled delivery of dexamethasone in acute lymphoblastic leukemia (ALL) therapy. The simulated data showed initial spikes in nanoparticle concentration in the liver, spleen, and kidneys, whereas concentration in plasma decreased rapidly. These simulation results were consistent with previously published in vivo data. At shorter time scales, the simulated data predicted decrease of nanoparticles from plasma with concomitant increase in the liver, spleen, and kidneys before decaying at longer timepoints. Interestingly, the simulated data predicted an unaccounted accumulation of about 50% of the injected dose of nanoparticles. Incorporation of an additional compartment into the model justified the presence of unaccounted nanoparticles in this compartment. Our results suggest that the proposed PBPK model can be an excellent tool for prediction of optimal dose of nanoparticle-encapsulated drugs for cancer treatment. PMID:26225236

  18. Fluorescence of aminofluoresceins as an indicative process allowing one to distinguish between micelles of cationic surfactants and micelle-like aggregates

    NASA Astrophysics Data System (ADS)

    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.

  19. Transferrin conjugated poly (γ-glutamic acid-maleimide-co-L-lactide)-1,2-dipalmitoylsn-glycero-3-phosphoethanolamine copolymer nanoparticles for targeting drug delivery.

    PubMed

    Zhao, Caiyan; Liu, Xiaoguang; Liu, Junxing; Yang, Zhiwei; Rong, Xianghui; Li, Mingjun; Liang, Xingjie; Wu, Yan

    2014-11-01

    Targeted drug delivery strategies have shown great potential in solving some problems of chemotherapy, such as non-selectivity and severe side effects, thus enhancing the anti-tumor efficiency of chemotherapeutic agents. In this work, we have prepared a novel nanoparticle consisted of amphiphilic poly(γ-glutamic acid-maleimide-co-L-lactide)-1,2-dipalmitoylsn-glycero-3-phosphoethanolamine (γ-PGA-MAL-PLA-DPPE) copolymer decorated with transferrin (Tf), which can specifically deliver anti-cancer drug paclitaxel (PTX) to the tumor cells for targeting chemotherapy. These nanoparticles (NPs) have preferable particle size, high encapsulation efficiency and a pH-dependent release profile. As expected, The Tf modification mediate specific targeting to nasopharyngeal carcinoma (C666-1) cells and human cervical carcinoma (Hela) cells with the transferrin receptor (TfR) overexpressed and enhance cellular uptake of the NPs, as demonstrated by flow cytometry and confocal microscopy assays. In vitro cytotoxicity studies reveal that the NPs have excellent biocompatibility, and the presence of Tf enhance the activity of PTX to the targeted cells. All these results prove that Tf modified γ-PGA-MAL-PLA-DPPE NPs could facilitate the tumor-specific therapy. Therefore, such a targeting drug delivery system provides significant advances toward cancer therapy. PMID:25454663

  20. Dual Stimuli-Responsive Hybrid Polymeric Nanoparticles Self-Assembled from POSS-Based Starlike Copolymer-Drug Conjugates for Efficient Intracellular Delivery of Hydrophobic Drugs.

    PubMed

    Yang, Qingqing; Li, Lian; Sun, Wei; Zhou, Zhou; Huang, Yuan

    2016-06-01

    To further fine tune drug release and enhance therapeutic effects of polyhedral oligomericsilsesquioxane (POSS)-based nanomedicine, a starlike organic-inorganic conjugate was synthesized by grafting semitelechelic N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers to a POSS rigid core through reductively degradable disulfide bonds. The hydrophobic docetaxel (DTX) was attached to the grafts by pH-sensitive hydrazone bonds and also encapsulated into the POSS core (SP-DTX). Thus, the final amphiphilic star-shaped conjugates could self-assemble into nanoparticles and exhibited conspicuous drug-loading capacity (20.1 wt %) based on the covalently conjugated accompanied by physically encapsulated DTX. The stimuli-responsive DTX release under acidic lysosomal and reducing cytoplasmic environments was verified, leading to enhanced cytotoxicity against PC-3 human prostate carcinoma cells. To evaluate the in vivo therapeutic effects of the DTX-loaded nanovehicles objectively, a stroma-rich, prostate xenograft tumor model was generated. SP-DTX displayed uniform tumor distribution and suppressed tumor growth to a more pronounced level (tumor inhibition of 78.9%) than nonredox-sensitive SP-DTX-A (67.4%), SP-DTX-C contained DTX only in the core (65.5%) or linear P-DTX (60.7%) through enhanced depletion of cancer-associated fibroblasts and induction of apoptosis. The hybrid POSS-based polymeric nanoparticles offer an efficient approach to transport hydrophobic drugs for cancer therapy. PMID:27167898

  1. Self-assembly of Random Copolymers

    PubMed Central

    Li, Longyu; Raghupathi, Kishore; Song, Cunfeng; Prasad, Priyaa; Thayumanavan, S.

    2014-01-01

    Self-assembly of random copolymers has attracted considerable attention recently. In this feature article, we highlight the use of random copolymers to prepare nanostructures with different morphologies and to prepare nanomaterials that are responsive to single or multiple stimuli. The synthesis of single-chain nanoparticles and their potential applications from random copolymers are also discussed in some detail. We aim to draw more attention to these easily accessible copolymers, which are likely to play an important role in translational polymer research. PMID:25036552

  2. The systematic tunability of nanoparticle dimensions through the controlled loading of surface-deposited diblock copolymer micelles.

    PubMed

    Krishnamoorthy, S; Pugin, R; Hinderling, C; Brugger, J; Heinzelmann, H

    2008-04-30

    The continuous tunability of iron oxide nanoparticle dimensions is demonstrated using the pH controlled loading of ferric nitrate from aqueous solution into polystyrene-block-polyacrylic acid reverse micelles deposited on a silicon substrate. Quasi-hexagonally ordered two-dimensional arrays of iron oxide nanoparticles with a systematic tunability of particle heights in the sub-10 nm regime and a constant periodicity are obtained and characterized with atomic force microscopy and x-ray photoelectron spectroscopy. PMID:21825665

  3. Effect of geochemical properties on degradation of trichloroethylene by stabilized zerovalent iron nanoparticle with Na-acrylic copolymer.

    PubMed

    Chen, Meng-yi; Su, Yuh-fan; Shih, Yang-hsin

    2014-11-01

    Stable nanoscale zero-valent iron (NZVI) particles have been developed to remediate chlorinated compounds. The degradation kinetics and efficiency of trichloroethylene (TCE) by a commercial stabilized NZVI with Na-acrylic copolymer (acNZVI) were investigated and compared with those by laboratory-synthesized NZVI and carboxymethyl cellulose (CMC)-stabilized NZVI particles. Results show that the degradation of TCE by acNZVI was faster than that by NZVI and CMC-NZVI. Increase in temperature enhanced the degradation rate and efficiency of TCE with acNZVI. The activation energy of TCE degradation by acNZVI was estimated to be 23 kJ/mol. The degradation rate constants of TCE decreased from 0.064 to 0.026 min(-1) with decrease in initial pH from 9.03 to 4.23. Common groundwater anions including NO3(-), Cl(-), HCO3(-), and SO4(2-) inhibited slightly the degradation efficiencies of TCE by acNZVI. The Na-acrylic copolymer-stabilized NZVI, which exhibited high degradation kinetics and efficiency, could be a good remediation agent for chlorinated organic compounds. PMID:24929499

  4. Engineered nanoparticles of Efavirenz using methacrylate co-polymer (Eudragit-E100) and its biological effects in-vivo.

    PubMed

    Hari, B N Vedha; Narayanan, N; Dhevendaran, K; Ramyadevi, D

    2016-10-01

    Nanotechnology in drug delivery is explored widely to improve therapeutic efficacy and minimize undesirable effects of several anti-HIV drugs. Efavirenz is a non-nucleoside reverse transcriptase inhibitor, prescribed as first-line drug of choice for treatment of AIDS. It is poorly soluble and exhibits variable bioavailability hence, a high oral dose is recommended for therapy. The present work focuses on improving the dissolution and bioavailability of Efavirenz through nano drug delivery approach. Polymeric nanoparticles were developed using Eudragit E100 and characterized for size, stability, morphology, cytotoxicity (MTT assay in T-lymphatic (C8166) cell lines) and in-vivo biodistribution in mice models. The optimized nanoparticles exhibited average particle size of 110nm, zeta potential of -33mV and entrapment efficiency 99%. The SEM images displayed the formation of nano-size particles. The cell viability was significantly improved in the nanoparticles (99%) compared to pure drug (15%) at the concentration of 8μg/mL. The in-vivo biodistribution profile of the nanoparticles showed considerably higher drug concentration in serum and major organs, especially in the brain compared to the free drug. The optimized Efavirenz loaded nanoparticles clearly demonstrated an increase in dissolution, drug distribution, and bioavailability, which implies better control over the therapeutic dosing. PMID:27287151

  5. Order and phase behavior of diblock copolymers and nano-particles mixture in confinement : A Molecular Dynamics study

    NASA Astrophysics Data System (ADS)

    Shagolsem, Lenin S.; Sommer, Jens-Uwe

    2010-03-01

    Diblock copolymers(DBC) and nano-particles(NP) composite show new structures apart from that of a pure DBC. Interesting effects are observed when such composite are in confined geometries. For example, morphology changes, inhomogeneous NP distribution and its effect on the formation of ordered structures. We study, via MD simulation, a coarse grained model of cylinder forming DBC and NP composite confined between walls (which can be neutral or selective) with a particular focus towards an understanding of its order and phase behavior in this restricted environment. In particular, we investigate the effect of temperature on the NP enrichment near the walls also orientation of cylinders for different wall separation. Further, we study how the variation of NP volume fraction affects segregation and morphology.

  6. Superparamagnetic iron oxide--loaded poly(lactic acid)-D-alpha-tocopherol polyethylene glycol 1000 succinate copolymer nanoparticles as MRI contrast agent.

    PubMed

    Prashant, Chandrasekharan; Dipak, Maity; Yang, Chang-Tong; Chuang, Kai-Hsiang; Jun, Ding; Feng, Si-Shen

    2010-07-01

    We developed a strategy to formulate supraparamagnetic iron oxides (SPIOs) in nanoparticles (NPs) of biodegradable copolymer made up of poly(lactic acid) (PLA) and d-alpha-tocopherol polyethylene glycol 1000 succinate (TPGS) for medical imaging by magnetic resonance imaging (MRI) of high contrast and low side effects. The IOs-loaded PLA-TPGS NPs (IOs-PNPs) were prepared by the single emulsion method and the nanoprecipitation method. Effects of the process parameters such as the emulsifier concentration, IOs loading in the nanoparticles, and the solvent to non-solvent ratio on the IOs distribution within the polymeric matrix were investigated and the formulation was then optimized. The transmission electron microscopy (TEM) showed direct visual evidence for the well dispersed distribution of the IOs within the NPs. We further investigated the biocompatibility and cellular uptake of the IOs-PNPs in vitro with MCF-7 breast cancer cells and NIH-3T3 mouse fibroblast in close comparison with the commercial IOs imaging agent Resovist. MRI imaging was further carried out to investigate the biodistribution of the IOs formulated in the IOs-PNPs, especially in the liver to understand the liver clearance process, which was also made in close comparison with Resovist. We found that the PLA-TPGS NPs formulation at the clinically approved dose of 0.8 mg Fe/kg could be cleared within 24 h in comparison with several weeks for Resovist. Xenograft tumor model MRI confirmed the advantages of the IOs-PNPs formulation versus Resovist through the enhanced permeation and retention (EPR) effect of the tumor vasculature. PMID:20434210

  7. Development of chitosan graft pluronic®F127 copolymer nanoparticles containing DNA aptamer for paclitaxel delivery to treat breast cancer cells

    NASA Astrophysics Data System (ADS)

    Thach Nguyen, Kim; Le, Duc Vinh; Do, Dinh Ho; Huan Le, Quang

    2016-06-01

    HER-2/ErbB2/Neu(HER-2), a member of the epidermal growth factor receptor family, is specifically overexpressed on the surface of breast cancer cells and serves a therapeutic target for breast cancer. In this study, we aimed to isolate DNA aptamer (Ap) that specifically bind to a HER-2 overexpressing SK-BR-3 human breast cancer cell line, using SELEX strategy. We developed a novel multifunctional composite micelle with surface modification of Ap for targeted delivery of paclitaxel. This binary mixed system consisting of Ap modified pluronic®F127 and chitosan could enhance PTX loading capacity and increase micelle stability. Polymeric micelles had a spherical shape and were self-assemblies of block copolymers of approximately 86.22 ± 1.45 nm diameter. PTX could be loaded with high encapsulation efficiency (83.28 ± 0.13%) and loading capacity (9.12 ± 0.34%). The release profile were 29%–35% in the first 12 h and 85%–93% after 12 d at pH 7.5 of receiving media. The IC50 doses by MTT assay showed the greater activity of nanoparticles loaded paclitaxel over free paclitaxel and killed cells up to 95% after 6 h. These results demonstrated unique assembly with the capacity to function as an efficient detection and delivery vehicle in the biological living system.

  8. Efficient anti-tumor effect of photodynamic treatment with polymeric nanoparticles composed of polyethylene glycol and polylactic acid block copolymer encapsulating hydrophobic porphyrin derivative.

    PubMed

    Ogawara, Ken-ichi; Shiraishi, Taro; Araki, Tomoya; Watanabe, Taka-ichi; Ono, Tsutomu; Higaki, Kazutaka

    2016-01-20

    To develop potent and safer formulation of photosensitizer for cancer photodynamic therapy (PDT), we tried to formulate hydrophobic porphyrin derivative, photoprotoporphyrin IX dimethyl ester (PppIX-DME), into polymeric nanoparticles composed of polyethylene glycol and polylactic acid block copolymer (PN-Por). The mean particle size of PN-Por prepared was around 80nm and the zeta potential was determined to be weakly negative. In vitro phototoxicity study for PN-Por clearly indicated the significant phototoxicity of PN-Por for three types of tumor cells tested (Colon-26 carcinoma (C26), B16BL6 melanoma and Lewis lung cancer cells) in the PppIX-DME concentration-dependent fashion. Furthermore, it was suggested that the release of PppIX-DME from PN-Por would gradually occur to provide the sustained release of PppIX-DME. In vivo pharmacokinetics of PN-Por after intravenous administration was evaluated in C26 tumor-bearing mice, and PN-Por exhibited low affinity to the liver and spleen and was therefore retained in the blood circulation for a long time, leading to the efficient tumor disposition of PN-Por. Furthermore, significant and highly effective anti-tumor effect was confirmed in C26 tumor-bearing mice with the local light irradiation onto C26 tumor tissues after PN-Por injection. These findings indicate the potency of PN-Por for the development of more efficient PDT-based cancer treatments. PMID:26593985

  9. Construction of paclitaxel-loaded poly (2-hydroxyethyl methacrylate)-g-poly (lactide)-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine copolymer nanoparticle delivery system and evaluation of its anticancer activity

    PubMed Central

    Ma, Xiaowei; Wang, Huan; Jin, Shubin; Wu, Yan; Liang, Xing-Jie

    2012-01-01

    Background There is an urgent need to develop drug-loaded biocompatible nanoscale packages with improved therapeutic efficacy for effective clinical treatment. To address this need, a novel poly (2-hydroxyethyl methacrylate)-poly (lactide)-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine [PHEMA-g-(PLA-DPPE)] copolymer was designed and synthesized to enable these nanoparticles to be pH responsive under pathological conditions. Methods The structural properties and thermal stability of the copolymer was measured and confirmed by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and thermogravimetric analysis. In order to evaluate its feasibility as a drug carrier, paclitaxel-loaded PHEMA-g-(PLA-DPPE) nanoparticles were prepared using the emulsion-solvent evaporation method. Results The PHEMA-g-(PLA-DPPE) nanoparticles could be efficiently loaded with paclitaxel and controlled to release the drug gradually and effectively. In vitro release experiments demonstrated that drug release was faster at pH 5.0 than at pH 7.4. The anticancer activity of the PHEMA-g-(PLA-DPPE) nanoparticles was measured in breast cancer MCF-7 cells in vivo and in vitro. In comparison with the free drug, the paclitaxel-loaded PHEMA-g-(PLA-DPPE) nanoparticles could induce more significant tumor regression. Conclusion This study indicates that PHEMA-g-(PLA-DPPE) nanoparticles are promising carriers for hydrophobic drugs. This system can passively target cancer tissue and release drugs in a controllable manner, as determined by the pH value of the area in which the drug accumulates. PMID:22419875

  10. Nanoparticle self-assembly in mixtures of phospholipids with styrene/maleic acid copolymers or fluorinated surfactants

    NASA Astrophysics Data System (ADS)

    Vargas, Carolyn; Arenas, Rodrigo Cuevas; Frotscher, Erik; Keller, Sandro

    2015-12-01

    Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and synthetic membranes and membrane proteins. Considerable efforts are currently underway to replace conventional detergents by milder alternatives such as styrene/maleic acid (SMA) copolymers and fluorinated surfactants. However, these compounds and their nanosized assemblies remain poorly understood as regards their interactions with lipid membranes, particularly, the thermodynamics of membrane partitioning and solubilisation. Using 19F and 31P nuclear magnetic resonance spectroscopy, static and dynamic light scattering, and isothermal titration calorimetry, we have systematically investigated the aggregational state of a zwitterionic bilayer-forming phospholipid upon exposure to an SMA polymer with a styrene/maleic acid ratio of 3 : 1 or to a fluorinated octyl phosphocholine derivative called F6OPC. The lipid interactions of SMA(3 : 1) and F6OPC can be thermodynamically conceptualised within the framework of a three-stage model that treats bilayer vesicles, discoidal or micellar nanostructures, and the aqueous solution as distinct pseudophases. The exceptional solubilising power of SMA(3 : 1) is reflected in very low membrane-saturating and solubilising polymer/lipid molar ratios of 0.10 and 0.15, respectively. Although F6OPC saturates bilayers at an even lower molar ratio of 0.031, this nondetergent does not solubilise lipids even at >1000-fold molar excess, thus highlighting fundamental differences between these two types of mild membrane-mimetic systems. We rationalise these findings in terms of a new classification of surfactants based on bilayer-to-micelle transfer free energies and discuss practical implications for membrane-protein research.Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and

  11. Nanoparticle self-assembly in mixtures of phospholipids with styrene/maleic acid copolymers or fluorinated surfactants.

    PubMed

    Vargas, Carolyn; Arenas, Rodrigo Cuevas; Frotscher, Erik; Keller, Sandro

    2015-12-28

    Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and synthetic membranes and membrane proteins. Considerable efforts are currently underway to replace conventional detergents by milder alternatives such as styrene/maleic acid (SMA) copolymers and fluorinated surfactants. However, these compounds and their nanosized assemblies remain poorly understood as regards their interactions with lipid membranes, particularly, the thermodynamics of membrane partitioning and solubilisation. Using (19)F and (31)P nuclear magnetic resonance spectroscopy, static and dynamic light scattering, and isothermal titration calorimetry, we have systematically investigated the aggregational state of a zwitterionic bilayer-forming phospholipid upon exposure to an SMA polymer with a styrene/maleic acid ratio of 3 : 1 or to a fluorinated octyl phosphocholine derivative called F(6)OPC. The lipid interactions of SMA(3 : 1) and F(6)OPC can be thermodynamically conceptualised within the framework of a three-stage model that treats bilayer vesicles, discoidal or micellar nanostructures, and the aqueous solution as distinct pseudophases. The exceptional solubilising power of SMA(3 : 1) is reflected in very low membrane-saturating and solubilising polymer/lipid molar ratios of 0.10 and 0.15, respectively. Although F(6)OPC saturates bilayers at an even lower molar ratio of 0.031, this nondetergent does not solubilise lipids even at >1000-fold molar excess, thus highlighting fundamental differences between these two types of mild membrane-mimetic systems. We rationalise these findings in terms of a new classification of surfactants based on bilayer-to-micelle transfer free energies and discuss practical implications for membrane-protein research. PMID:26599076

  12. Enhanced Antifungal Activity by Ab-Modified Amphotericin B-Loaded Nanoparticles Using a pH-Responsive Block Copolymer

    NASA Astrophysics Data System (ADS)

    Tang, Xiaolong; Dai, Jingjing; Xie, Jun; Zhu, Yongqiang; Zhu, Ming; Wang, Zhi; Xie, Chunmei; Yao, Aixia; Liu, Tingting; Wang, Xiaoyu; Chen, Li; Jiang, Qinglin; Wang, Shulei; Liang, Yong; Xu, Congjing

    2015-06-01

    Fungal infections are an important cause of morbidity and mortality in immunocompromised patients. Amphotericin B (AMB), with broad-spectrum antifungal activity, has long been recognized as a powerful fungicidal drug, but its clinical toxicities mainly nephrotoxicity and poor solubility limit its wide application in clinical practice. The fungal metabolism along with the host immune response usually generates acidity at sites of infection, resulting in loss of AMB activity in a pH-dependent manner. Herein, we developed pH-responsive AMB-loaded and surface charge-switching poly( d, l-lactic- co-glycolic acid)- b-poly( l-histidine)- b-poly(ethylene glycol) (PLGA-PLH-PEG) nanoparticles for resolving the localized acidity problem and enhance the antifungal efficacy of AMB. Moreover, we modified AMB-encapsulated PLGA-PLH-PEG nanoparticles with anti- Candida albicans antibody (CDA) (CDA-AMB-NPs) to increase the targetability. Then, CDA-AMB-NPs were characterized in terms of physical characteristics, in vitro drug release, stability, drug encapsulation efficiency, and toxicity. Finally, the targetability and antifungal activity of CDA-AMB-NPs were investigated in vitro /in vivo. The result demonstrated that CDA-AMB-NPs significantly improve the targetability and bioavailability of AMB and thus improve its antifungal activity and reduce its toxicity. These NPs may become a good drug carrier for antifungal treatment.

  13. Iron oxide nanoparticles grafted with sulfonated copolymers are stable in concentrated brine at elevated temperatures and weakly adsorb on silica.

    PubMed

    Bagaria, Hitesh G; Xue, Zheng; Neilson, Bethany M; Worthen, Andrew J; Yoon, Ki Youl; Nayak, Susheela; Cheng, Victoria; Lee, Jae Ho; Bielawski, Christopher W; Johnston, Keith P

    2013-04-24

    Magnetic nanoparticles that can be transported in subsurface reservoirs at high salinities and temperatures are expected to have a major impact on enhanced oil recovery, carbon dioxide sequestration, and electromagnetic imaging. Herein we report a rare example of steric stabilization of iron oxide (IO) nanoparticles (NPs) grafted with poly(2-acrylamido-2-methylpropanesulfonate-co-acrylic acid) (poly(AMPS-co-AA)) that not only display colloidal stability in standard American Petroleum Institute (API) brine (8% NaCl + 2% CaCl2 by weight) at 90 °C for 1 month but also resist undesirable adsorption on silica surfaces (0.4% monolayer NPs). Because the AMPS groups interacted weakly with Ca(2+), they were sufficiently well solvated to provide steric stabilization. The PAA groups, in contrast, enabled covalent grafting of the poly(AMPS-co-AA) chains to amine-functionalized IO NPs via formation of amide bonds and prevented polymer desorption even after a 40,000-fold dilution. The aforementioned methodology may be readily adapted to stabilize a variety of other functional inorganic and organic NPs at high salinities and temperatures. PMID:23527819

  14. Morphology diagrams for A2B copolymer melts: real-space self-consistent field theory

    SciTech Connect

    Kumar, Rajeev; Sides, Scott; Mays, Jimmy; Li, Yige; Sumpter, Bobby G

    2012-01-01

    Morphology diagrams for A2B copolymer melts are constructed using real-space self-consistent field theory (SCFT). In particular, the effect of architectural asymmetry on the morphology diagram is studied. It is shown that asymmetry in the lengths of A arms in the A2B copolymer melts aids in the microphase separation. As a result, the disorder-order transition boundaries for the A2B copolymer melts are shown to shift downward in terms of N, and N being the Flory s chi parameter and the total number of the Kuhn segments,respectively, in comparison with the A2B copolymers containing symmetric A arms. Furthermore, perforated lamellar (PL) and a micelle-like (M) microphase segregated morphologies are found to compete with the classical morphologies namely, lamellar, cylinders, spheres and gyroid. The PL morphology is found to be stable for A2B copolymers containing asymmetric A arms and M is found to be metastable for the parameter range explored in this work.

  15. Lysine-tagged peptide coupling onto polylactide nanoparticles coated with activated ester-based amphiphilic copolymer: a route to highly peptide-functionalized biodegradable carriers.

    PubMed

    Handké, Nadège; Ficheux, Damien; Rollet, Marion; Delair, Thierry; Mabrouk, Kamel; Bertin, Denis; Gigmes, Didier; Verrier, Bernard; Trimaille, Thomas

    2013-03-01

    Efficient biomolecule conjugation to the surface of biodegradable colloidal carriers is crucial for their targeting efficiency in drug/vaccine delivery applications. We here propose a potent strategy to drastically improve peptide immobilization on biodegradable polylactide (PLA) nanoparticles (NPs). Our approach particularly relies on the use of an amphiphilic block copolymer PLA-b-poly(N-acryloxysuccinimide-co-N-vinylpyrrolidone) (PLA-b-P(NAS-co-NVP)) as NP surface modifier, whose the N-succinimidyl (NS) ester functions of the NAS units along the polymer chain ensure N-terminal amine peptide coupling. The well-known immunostimulatory peptide sequence derived from the human interleukin 1β (IL-1β), VQGEESNDK, was coupled on the NPs of 169 nm mean diameter in phosphate buffer (pH 8, 10 mM). A maximum amount of 2 mg immobilized per gram of NPs (i.e. 0.042 peptidenm(-2)) was obtained. Introduction of a three lysine tag at the peptide N-terminus (KKKVQGEESNDK) resulted in a dramatic improvement of the immobilized peptide amounts (27.5 mg/g NP, i.e. 0.417 peptidenm(-2)). As a comparison, the density of tagged peptide achievable on surfactant free PLA NPs of similar size (140 nm), through classical EDC or EDC/NHS activation of the surface PLA carboxylic end-groups, was found to be 6 mg/g NP (i.e. 0.075 peptidenm(-2)), showing the decisive impact of the P(NAS-co-NVP)-based hairy corona for high peptide coupling. These results demonstrate that combined use of lysine tag and PLA-b-P(NAS-co-NVP) surfactant represents a valuable platform to tune and optimize surface bio-functionalization of PLA-based biodegradable carriers. PMID:23277324

  16. Using silver nano-particle ink in electrode fabrication of high frequency copolymer ultrasonic transducers: modeling and experimental investigation.

    PubMed

    Decharat, Adit; Wagle, Sanat; Jacobsen, Svein; Melandsø, Frank

    2015-01-01

    High frequency polymer-based ultrasonic transducers are produced with electrodes thicknesses typical for printed electrodes obtained from silver (Ag) nano-particle inks. An analytical three-port network is used to study the acoustic effects imposed by a thick electrode in a typical layered transducer configuration. Results from the network model are compared to experimental findings for the implemented transducer configuration, to obtain a better understanding of acoustical effects caused by the additional printed mass loading. The proposed investigation might be supportive of identification of suitable electrode-depositing methods. It is also believed to be useful as a feasibility study for printed Ag-based electrodes in high frequency transducers, which may reduce both the cost and production complexity of these devices. PMID:25903552

  17. Using Silver Nano-Particle Ink in Electrode Fabrication of High Frequency Copolymer Ultrasonic Transducers: Modeling and Experimental Investigation

    PubMed Central

    Decharat, Adit; Wagle, Sanat; Jacobsen, Svein; Melandsø, Frank

    2015-01-01

    High frequency polymer-based ultrasonic transducers are produced with electrodes thicknesses typical for printed electrodes obtained from silver (Ag) nano-particle inks. An analytical three-port network is used to study the acoustic effects imposed by a thick electrode in a typical layered transducer configuration. Results from the network model are compared to experimental findings for the implemented transducer configuration, to obtain a better understanding of acoustical effects caused by the additional printed mass loading. The proposed investigation might be supportive of identification of suitable electrode-depositing methods. It is also believed to be useful as a feasibility study for printed Ag-based electrodes in high frequency transducers, which may reduce both the cost and production complexity of these devices. PMID:25903552

  18. Block copolymer investigations

    NASA Astrophysics Data System (ADS)

    Yufa, Nataliya A.

    The research presented in this thesis deals with various aspects of block copolymers on the nanoscale: their behavior at a range of temperatures, their use as scaffolds, or for creation of chemically striped surfaces, as well as the behavior of metals on block copolymers under the influence of UV light, and the healing behavior of copolymers. Invented around the time of World War II, copolymers have been used for decades due to their macroscopic properties, such as their ability to be molded without vulcanization, and the fact that, unlike rubber, they can be recycled. In recent years, block copolymers (BCPs) have been used for lithography, as scaffolds for nano-objects, to create a magnetic hard drive, as well as in photonic and other applications. In this work we used primarily atomic force microscopy (AFM) and transmission electron microscopy (TEM), described in Chapter II, to conduct our studies. In Chapter III we demonstrate a new and general method for positioning nanoparticles within nanoscale grooves. This technique is suitable for nanodots, nanocrystals, as well as DNA. We use AFM and TEM to demonstrate selective decoration. In Chapters IV and V we use AFM and TEM to study the structure of polymer surfaces coated with metals and self-assembled monolayers. We describe how the surfaces were created, exhibit their structure on the nanoscale, and prove that their macroscopic wetting properties have been altered compared to the original polymer structures. Finally, Chapters VI and VII report out in-situ AFM studies of BCP at high temperatures, made possible only recently with the invention of air-tight high-temperature AFM imaging cells. We locate the transition between disordered films and cylinders during initial ordering. Fluctuations of existing domains leading to domain coarsening are also described, and are shown to be consistent with reptation and curvature minimization. Chapter VII deals with the healing of PS-b-PMMA following AFM-tip lithography or

  19. Chondroitin sulfate-polyethylenimine copolymer-coated superparamagnetic iron oxide nanoparticles as an efficient magneto-gene carrier for microRNA-encoding plasmid DNA delivery

    NASA Astrophysics Data System (ADS)

    Lo, Yu-Lun; Chou, Han-Lin; Liao, Zi-Xian; Huang, Shih-Jer; Ke, Jyun-Han; Liu, Yu-Sheng; Chiu, Chien-Chih; Wang, Li-Fang

    2015-04-01

    MicroRNA-128 (miR-128) is an attractive therapeutic molecule with powerful glioblastoma regulation properties. However, miR-128 lacks biological stability and leads to poor delivery efficacy in clinical applications. In our previous study, we demonstrated two effective transgene carriers, including polyethylenimine (PEI)-decorated superparamagnetic iron oxide nanoparticles (SPIONs) as well as chemically-conjugated chondroitin sulfate-PEI copolymers (CPs). In this contribution, we report optimized conditions for coating CPs onto the surfaces of SPIONs, forming CPIOs, for magneto-gene delivery systems. The optimized weight ratio of the CPs and SPIONs is 2 : 1, which resulted in the formation of a stable particle as a good transgene carrier. The hydrodynamic diameter of the CPIOs is ~136 nm. The gel electrophoresis results demonstrate that the weight ratio of CPIO/DNA required to completely encapsulate pDNA is >=3. The in vitro tests of CPIO/DNA were done in 293 T, CRL5802, and U87-MG cells in the presence and absence of an external magnetic field. The magnetofection efficiency of CPIO/DNA was measured in the three cell lines with or without fetal bovine serum (FBS). CPIO/DNA exhibited remarkably improved gene expression in the presence of the magnetic field and 10% FBS as compared with a gold non-viral standard, PEI/DNA, and a commercial magnetofection reagent, PolyMag/DNA. In addition, CPIO/DNA showed less cytotoxicity than PEI/DNA and PolyMag/DNA against the three cell lines. The transfection efficiency of the magnetoplex improved significantly with an assisted magnetic field. In miR-128 delivery, a microRNA plate array and fluorescence in situ hybridization were used to demonstrate that CPIO/pMIRNA-128 indeed expresses more miR-128 with the assisted magnetic field than without. In a biodistribution test, CPIO/Cy5-DNA showed higher accumulation at the tumor site where an external magnet is placed nearby.MicroRNA-128 (miR-128) is an attractive therapeutic molecule

  20. Amphiphilic PEO-b-PBLG diblock and PBLG-b-PEO-b-PBLG triblock copolymer based nanoparticles: doxorubicin loading and in vitro evaluation.

    PubMed

    Kakkar, Dipti; Mazzaferro, Silvia; Thevenot, Julie; Schatz, Christophe; Bhatt, Anant; Dwarakanath, Bilikere S; Singh, Harpal; Mishra, Anil K; Lecommandoux, Sebastien

    2015-01-01

    Huisgen's 1,3-dipolar cycloaddition ("Click Chemestry") has been used to prepare amphiphilic PEO-b-PBLG diblock and PBLG-b-PEO-b-PBLG triblock copolymers as potential carriers of anticancer drugs. Spherical and flower shaped micelles (D ≈ 100 nm) were obtained from diblock and triblock copolymers respectively. DOX was effectively encapsulated up to 18 wt.% and 50-60% of it was steadily released from the micelles over a period of 7 d. Flow cytometry and fluorescence microscopy confirmed the effective intracellular uptake as well as the sustained release of DOX from micelles. These results suggest that the diblock as well as triblock copolymers are promising carriers for intra-cellular drug delivery. PMID:25557884

  1. Junction-Controlled Elasticity of Single-Walled Carbon Nanotube Dispersions in Acrylic Copolymer Gels and Solutions

    SciTech Connect

    Schoch, Andrew B.; Shull, Kenneth R.; Brinson, L. Catherine

    2008-08-26

    Oscillatory shear rheometry is used to study the mechanical response of single-walled carbon nanotubes dispersed in solutions of acrylic diblock or triblock copolymers in 2-ethyl-1-hexanol. Thermal transitions in the copolymer solutions provide a route for the easy processing of these composite materials, with excellent dispersion of the nanotubes as verified by near-infrared photoluminescence spectroscopy. The nanotube dispersions form elastic networks with properties that are controlled by the junction points between nanotubes, featuring a temperature-dependent elastic response that is controlled by the dynamic properties of the matrix copolymer solution. The data are consistent with the formation of micelle-like aggregates around the nanotubes. At low temperatures the core-forming poly(methyl methacrylate) blocks are glassy, and the overall mechanical response of the composite does not evolve with time. At higher temperatures the enhanced mobility of the core-forming blocks enables the junctions to achieve more intimate nanotube-nanotube contact, and the composite modulus increases with time. These aging effects are observed in both diblock and triblock copolymer solutions but are partially reversed in the triblock solutions by cooling through the gel transition of the triblock copolymer. This result is attributed to the generation of internal stresses during gelation and the ability of these stresses to break or weaken the nanotube junctions.

  2. Block Copolymer Nanocomposites in Electric Fields: Kinetics of Alignment

    SciTech Connect

    Liedel, Clemens; Pester, Christian; Ruppel, Markus A; Lewin, Christian; Pavan, Mariela J.; Urban, Volker S; Shenhar, Roy; Bosecke, Peter; Boker, Alexander

    2013-01-01

    We investigate the kinetics of block copolymer/nanoparticle composite alignment in an electric field using in situ transmission small-angle X-ray scattering. As a model system, we employ a lamellae forming polystyrene-block-poly(2-vinyl pyridine) block copolymer with different contents of gold nanoparticles in thick films under solvent vapor annealing. While the alignment improves with increasing nanoparticle fraction, the kinetics slows down. This is explained by changes in the degree of phase separation and viscosity. Our findings provide extended insights into the basics of nanocomposite alignment.

  3. Phase separations in a copolymer copolymer mixture

    NASA Astrophysics Data System (ADS)

    Zhang, Jin-Jun; Jin, Guojun; Ma, Yuqiang

    2006-01-01

    We propose a three-order-parameter model to study the phase separations in a diblock copolymer-diblock copolymer mixture. The cell dynamical simulations provide rich information about the phase evolution and structural formation, especially the appearance of onion-rings. The parametric dependence and physical reason for the domain growth of onion-rings are discussed.

  4. Probing nanoparticle effect in protein-surfactant complexes

    NASA Astrophysics Data System (ADS)

    Mehan, Sumit; Aswal, V. K.; Kohlbrecher, J.

    2015-06-01

    SANS experiments have been carried to probe the role of anionic silica nanoparticles in the anionic BSA protein-cationic DTAB surfactant complexes. In protein-surfactant complex, surfactant molecules aggregate to form micelle-like clusters along the unfolded polypeptide chains of the protein. The nanoparticle aggregation mediated by oppositely charged protein-surfactant complex coexists with the free protein-surfactant complexes in the nanoparticle-protein-surfactant system. There is rearrangement of micelles in adsorbed protein-surfactant complex on nanoparticles in leading to their (nanoparticle) aggregation. On the other hand, the unfolding of protein in free protein-surfactant complex is found to be significantly enhanced in presence of nanoparticles.

  5. Solvent enhanced block copolymer ordering in thin films

    NASA Astrophysics Data System (ADS)

    Misner, Matthew J.

    Diblock copolymer self-assembly of materials is emerging as a key element in the fabrication of functional nanostructured materials. By solvent casting or solvent annealing block copolymer thin films, we have demonstrated methods to produce diblock copolymer films with highly oriented, close-packed arrays of nanoscopic cylindrical domains with a high degree of long-range lateral order with few defects. The solvent imparts a high degree of mobility in the microphase-separated copolymer that enables a rapid removal of defects and a high degree of lateral order. Though the use of a selective cosolvent during solvent casting, it was found that the microdomain size and spacing could be increased, leading to a size-tunable system. Additionally, the presence of water also led to the ability to control the microdomain orientation during solvent annealing. Ionic complexation within cylinder-forming PS- b-EO block copolymer thin films was also investigated, where added salts bind PEO block as the minor component. Small amounts of added salts, on the order a few ions per chain, show large effects on the ordering of the copolymer films during solvent annealing. By using gold or cobalt salts, well-organized patterns of nanoparticles can be generated in the copolymer microdomains. Topographically and chemically patterned surfaces were used as a route to sectorizing and controlling the lattice orientation of copolymer films. Topographically patterned surfaces allow well-defined boundaries to confine the copolymer microdomains on a surface and effectively direct the ordering and grain orientation of the copolymer microdomains. Chemically patterned surfaces provide a route to direct the block copolymer ordering on completely flat surface, which may have advantages in applications where adding additional topography may be undesirable. To generate nanoporous templates from PS-b-PEO bases materials several routs were followed. The first route was through the addition and selective

  6. Subchronic toxicity and immunotoxicity of MeO-PEG-poly(D,L-lactic-co-glycolic acid)-PEG-OMe triblock copolymer nanoparticles delivered intravenously into rats

    NASA Astrophysics Data System (ADS)

    Liao, Longfei; Zhang, Mengtian; Liu, Huan; Zhang, Xuanmiao; Xie, Zhaolu; Zhang, Zhirong; Gong, Tao; Sun, Xun

    2014-06-01

    Although monomethoxy(polyethyleneglycol)-poly (D,L-lactic-co-glycolic acid)-monomethoxy (PELGE) nanoparticles have been widely studied as a drug delivery system, little is known about their toxicity in vivo. Here we examined the subchronic toxicity and immunotoxicity of different doses of PELGE nanoparticles with diameters of 50 and 200 nm (PELGE50 and PELGE200) in rats. Neither size of PELGE nanoparticles showed obvious subchronic toxic effects during 28 d of continuous intravenous administration based on clinical observation, body weight, hematology parameters and histopathology analysis. PELGE200 nanoparticles showed no overt signs of immunotoxicity based on organ coefficients, histopathology analysis, immunoglobulin levels, blood lymphocyte subpopulations and splenocyte cytokines. Conversely, PELGE50 nanoparticles were associated with an increased organ coefficient and histopathological changes in the spleen, increased serum IgM and IgG levels, alterations in blood lymphocyte subpopulations and enhanced expression of spleen interferon-γ. Taken together, these results suggest that PELGE nanoparticles show low subchronic toxicity but substantial immunotoxicity, which depends strongly on particle size. These findings will be useful for safe application of PELGE nanoparticles in drug delivery systems.

  7. Are block copolymer worms more effective Pickering emulsifiers than block copolymer spheres?

    PubMed

    Thompson, K L; Mable, C J; Cockram, A; Warren, N J; Cunningham, V J; Jones, E R; Verber, R; Armes, S P

    2014-11-21

    RAFT-mediated polymerisation-induced self-assembly (PISA) is used to prepare six types of amphiphilic block copolymer nanoparticles which were subsequently evaluated as putative Pickering emulsifiers for the stabilisation of n-dodecane-in-water emulsions. It was found that linear poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) (PGMA-PHPMA) diblock copolymer spheres and worms do not survive the high shear homogenisation conditions used for emulsification. Stable emulsions are obtained, but the copolymer acts as a polymeric surfactant; individual chains rather than particles are adsorbed at the oil-water interface. Particle dissociation during emulsification is attributed to the weakly hydrophobic character of the PHPMA block. Covalent stabilisation of these copolymer spheres or worms can be readily achieved by addition of ethylene glycol dimethacrylate (EGDMA) during the PISA synthesis. TEM studies confirm that the resulting cross-linked spherical or worm-like nanoparticles survive emulsification and produce genuine Pickering emulsions. Alternatively, stabilisation can be achieved by either replacing or supplementing the PHPMA block with the more hydrophobic poly(benzyl methacrylate) (PBzMA). The resulting linear spheres or worms also survive emulsification and produce stable n-dodecane-in-water Pickering emulsions. The intrinsic advantages of anisotropic worms over isotropic spheres for the preparation of Pickering emulsions are highlighted. The former particles are more strongly adsorbed at similar efficiencies compared to spheres and also enable smaller oil droplets to be produced for a given copolymer concentration. The scalable nature of PISA formulations augurs well for potential applications of anisotropic block copolymer nanoparticles as Pickering emulsifiers. PMID:25254485

  8. Protein based Block Copolymers

    PubMed Central

    Rabotyagova, Olena S.; Cebe, Peggy; Kaplan, David L.

    2011-01-01

    Advances in genetic engineering have led to the synthesis of protein-based block copolymers with control of chemistry and molecular weight, resulting in unique physical and biological properties. The benefits from incorporating peptide blocks into copolymer designs arise from the fundamental properties of proteins to adopt ordered conformations and to undergo self-assembly, providing control over structure formation at various length scales when compared to conventional block copolymers. This review covers the synthesis, structure, assembly, properties, and applications of protein-based block copolymers. PMID:21235251

  9. Low-cost nanoparticles sorbent from modified rice husk and a copolymer for efficient removal of Pb(II) and crystal violet from water.

    PubMed

    Masoumi, Arameh; Hemmati, Khadijeh; Ghaemy, Mousa

    2016-03-01

    In this work, preparation of adsorbent nanoparticles based on treated low-value agricultural by-product rice husk (TARH), and poly(methylmethacrylate-co-maleic anhydride), poly(MMA-co-MA), is reported for the removal of Pb(II) ion and Crystal violet dye from water. The prepared adsorbent was characterized by FT-IR, SEM, AFM, DLS, BET and Zeta potential. The metal ion adsorption capability was determined for rice husk (RH), TARH, crosslinked poly(MMA-co-MA) (CNR), and CNR@TARH nanoparticles. Different factors affecting the adsorption of Pb(II) such as pH, contact time, initial metal ion concentration and also temperature were studied to investigate adsorption isotherms, kinetics and thermodynamics. For the four tested adsorption isotherm models, the equilibrium sorption data for CNR@TARH nanoparticles obeyed the Langmuir isotherm equation with maximum sorption capacity of 93.45 mg g(-1). The kinetic adsorption data fitted best the Lagergren pseudo-second order model. Regeneration of adsorbent was easily performed by adsorption/desorption experiments followed for 4 cycles. Finally, the ability of the nanoparticles to remove Crystal violet dye from aqueous solution was also investigated by varying the initial dye concentration, pH and immersion time and the adsorption mechanism followed the second-order kinetic model. PMID:26735725

  10. Interfacial functionalization and engineering of nanoparticles

    NASA Astrophysics Data System (ADS)

    Song, Yang

    also of the metal elements in the nanoparticle cores, in contrast to the bulk-exchange counterparts where these distributions were homogeneous within the nanoparticles, as manifested in contact angle, UV--vis, XPS, and TEM measurements. More interestingly, the electrocatalytic performance of the Janus nanoparticles was markedly better than the bulk-exchange ones, suggesting that the segregated distribution of the polar ligands from the apolar ones might further facilitate charge transfer from Ag to Au in the nanoparticle cores, leading to additional improvement of the adsorption and reduction of oxygen. This interfacial protocol was then adopted to prepare trimetallic Ag AuPt Neapolitan nanoparticles by two sequential galvanic exchange reactions of 1-hexanethiolate-capped silver nanoparticles with gold(I)-thiomalic acid and platinum(II)-hexanethiolate complexes. As both reactions were confined to an interface, the Au and Pt elements were situated on two opposite poles of the original Ag nanoparticles, which was clearly manifested in elemental mapping of the nanoparticles, and consistent with the damping and red-shift of the nanoparticle surface plasmon resonance. As nanoscale analogs to conventional amphiphilic molecules, the resulting Janus nanoparticles were found to form oil-in-water micelle-like or water-in-oil reverse micelle-like superparticulate structures depending on the solvent media. These unique characteristics were exploited for the effective transfer of diverse guest nanoparticles between organic and water phase. The transfer of hydrophobic nanoparticles from organic to water media or water-soluble nanoparticles to the organic phase was evidenced by TEM, DLS, UV-Vis, and PL measurements. In particular, line scans based on EDS analysis showed that the vesicle-like structures consisted of multiple layers of the Janus nanoparticles, which encapsulated the guest nanoparticles in the cores. The results highlight the unique effectiveness of using Janus

  11. Silicone/Acrylate Copolymers

    NASA Technical Reports Server (NTRS)

    Dennis, W. E.

    1982-01-01

    Two-step process forms silicone/acrylate copolymers. Resulting acrylate functional fluid is reacted with other ingredients to produce copolymer. Films of polymer were formed by simply pouring or spraying mixture and allowing solvent to evaporate. Films showed good weatherability. Durable, clear polymer films protect photovoltaic cells.

  12. Confinement of block copolymers

    SciTech Connect

    1995-12-31

    The following were studied: confinement of block copolymers, free surface confinement, effects of substrate interactions, random copolymers at homopolymer interfaces, phase separation in thin film polymer mixtures, buffing of polymer surfaces, and near edge x-ray absorption fine structure spectroscopy.

  13. Final Report: Grant DE-FG02-05ER15682. Simulation of Complex Microphase Formation in Pure and Nanoparticle-filled Diblock Copolymers

    SciTech Connect

    Fernando A. Escobedo

    2009-11-18

    The goal of this project was to use molecular simulation to quantify the impact of additives on the onset and structure of bicontinuous phases in linear diblock copolymers (DBC). The focus was on understanding how additives with selective affinity for a given block will distribute and perturb the structure of complex bicontinuous phases (like gyroid, double diamond, and plumbers nightmare whose minority component block forms two interweaving 3D networks) in DBCs; it was hypothesized that a suitable choice of additive type, size, affinity, and concentration may suppress or stabilize a particular bicontinuous phase. The ultimate goal in this line of investigation is to elucidate the rational design of the optimal additive for which the composition range of stability of a particular bicontinuous phase is maximized. Ours are the first published simulation studies to report on the formation of the gyroid phase in DBC melts and of other bicontinuous phases in DBC-modified by homopolymer. The following tasks were carried out: (i) simulation of bicontinuous phases of pure DBCs via both on-lattice Monte Carlo simulations and continuum-space Monte Carlo and molecular dynamics simulations, (ii) determination of the effect of selective additives (homopolymer) of different sizes on such bicontinuous phases, and (iii) development of novel Monte Carlo methods to map out reliable phase diagrams and improve ergodic sampling; in particular, optimized expanded-ensemble techniques for measuring free-energies and for chemical potential equilibration.

  14. Sequence-Specific Copolymer Compatibilizers designed via a Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Meenakshisundaram, Venkatesh; Patra, Tarak; Hung, Jui-Hsiang; Simmons, David

    For several decades, block copolymers have been employed as surfactants to reduce interfacial energy for applications from emulsification to surface adhesion. While the simplest approach employs symmetric diblocks, studies have examined asymmetric diblocks, multiblock copolymers, gradient copolymers, and copolymer-grafted nanoparticles. However, there exists no established approach to determining the optimal copolymer compatibilizer sequence for a given application. Here we employ molecular dynamics simulations within a genetic algorithm to identify copolymer surfactant sequences yielding maximum reductions the interfacial energy of model immiscible polymers. The optimal copolymer sequence depends significantly on surfactant concentration. Most surprisingly, at high surface concentrations, where the surfactant achieves the greatest interfacial energy reduction, specific non-periodic sequences are found to significantly outperform any regularly blocky sequence. This emergence of polymer sequence-specificity within a non-sequenced environment adds to a recent body of work suggesting that specific sequence may have the potential to play a greater role in polymer properties than previously understood. We acknowledge the W. M. Keck Foundation for financial support of this research.

  15. Effect of cationic grafted copolymer structure on the encapsulation of bovine serum albumin.

    PubMed

    Flynn, Nicholas; Topal, Ç Özge; Hikkaduwa Koralege, Rangika S; Hartson, Steve; Ranjan, Ashish; Liu, Jing; Pope, Carey; Ramsey, Joshua D

    2016-05-01

    The aim of the present study was to evaluate a library of poly-L-lysine (PLL)-graft (g)-polyethylene glycol (PEG) copolymers for the ability to encapsulate effectively a model protein, bovine serum albumin (BSA), and to characterize the stability and protein function of the resulting nanoparticle. A library of nine grafted copolymers was produced by varying PLL molecular weight and PEG grafting ratio. Electrostatic self-assembly of the protein and the grafted copolymer drove encapsulation. The formation of protein/polymer nanoparticles with a core/shell structure was confirmed using PAGE, dynamic light scattering, and electron microscopy. Encapsulation of the BSA into nanoparticles was strongly dependent on the copolymer-to-protein mass ratio, PEG grafting ratio, and PLL molecular weight. A copolymer-to-protein mass ratio of 7:1 and higher was generally required for high levels of encapsulation, and under these conditions, no loss of protein activity was observed. Copolymer characteristics also influenced nanoparticle resistance to polyanions and protease degradation. The results indicate that a copolymer of 15-30 kDa PLL, with a PEG grafting ratio of 10:1, is most promising for protein delivery. PMID:26952455

  16. Antimicrobial Graft Copolymer Gels.

    PubMed

    Harvey, Amanda C; Madsen, Jeppe; Douglas, C W Ian; MacNeil, Sheila; Armes, Steven P

    2016-08-01

    In view of the growing worldwide rise in microbial resistance, there is considerable interest in designing new antimicrobial copolymers. The aim of the current study was to investigate the relationship between antimicrobial activity and copolymer composition/architecture to gain a better understanding of their mechanism of action. Specifically, the antibacterial activity of several copolymers based on 2-(methacryloyloxy)ethyl phosphorylcholine [MPC] and 2-hydroxypropyl methacrylate (HPMA) toward Staphylococcus aureus was examined. Both block and graft copolymers were synthesized using either atom transfer radical polymerization or reversible addition-fragmentation chain transfer polymerization and characterized via (1)H NMR, gel permeation chromatography, rheology, and surface tensiometry. Antimicrobial activity was assessed using a range of well-known assays, including direct contact, live/dead staining, and the release of lactate dehydrogenase (LDH), while transmission electron microscopy was used to study the morphology of the bacteria before and after the addition of various copolymers. As expected, PMPC homopolymer was biocompatible but possessed no discernible antimicrobial activity. PMPC-based graft copolymers comprising PHPMA side chains (i.e. PMPC-g-PHPMA) significantly reduced both bacterial growth and viability. In contrast, a PMPC-PHPMA diblock copolymer comprising a PMPC stabilizer block and a hydrophobic core-forming PHPMA block did not exhibit any antimicrobial activity, although it did form a biocompatible worm gel. Surface tensiometry studies and LDH release assays suggest that the PMPC-g-PHPMA graft copolymer exhibits surfactant-like activity. Thus, the observed antimicrobial activity is likely to be the result of the weakly hydrophobic PHPMA chains penetrating (and hence rupturing) the bacterial membrane. PMID:27409712

  17. Bismaleimide Copolymer Matrix Resins

    NASA Technical Reports Server (NTRS)

    Parker, John A.; Heimbuch, Alvin H.; Hsu, Ming-Ta S.; Chen, Timothy S.

    1987-01-01

    Graphite composites, prepared from 1:1 copolymer of two new bismaleimides based on N,N'-m-phenylene-bis(m-amino-benzamide) structure have mechanical properties superior to those prepared from other bismaleimide-type resins. New heat-resistant composites replace metal in some structural applications. Monomers used to form copolymers with superior mechanical properties prepared by reaction of MMAB with maleic or citraconic anhydride.

  18. Biodegradable Self-Assembled Nanoparticles of Galactose-Containing Amphiphilic Triblock Copolymers for Targeted Delivery of Paclitaxel to HepG2 Cells.

    PubMed

    Wang, Tieshi; Tang, Xinde; Han, Jingtian; Ding, Yuanyuan; Guo, Wenjuan; Pei, Meishan

    2016-05-01

    Biodegradable self-assembled polymeric nanoparticles (NPs) composed of poly(6-O-methacryloyl-D-galactopyranose)-b-poly(L-lactide)-b-poly(6-O-methacryloyl-D-galactopyranose) (PMAGP-b-PLA-b-PMAGP) are prepared as carriers for the hydrophobic anticancer drug paclitaxel (PTX), to achieve target delivery to hepatoma cells. PTX can be encapsulated by the NPs with various molar ratios of L-lactide (LA) and 6-O-methacryloyl-D-galactopyranose (MAGP) during the process of self-assembly, and the resulting NPs exhibit high drug loading efficacy and substantial stability in aqueous solution. The size, size distribution, and morphology of the NPs are characterized using a Zetasizer Nano ZS and transmission electron microscopy. The hemolysis assay and cell cytotoxicity assay indicate that the polymeric NPs are biocompatible and non-toxic. The cellular uptake assay demonstrates that the galactose-containing NPs can be selectively recognized and subsequently accumulate in HepG2 cells. All of these results demonstrate that galactose-containing polymeric NPs are potential carriers for hepatoma-targeted drug delivery and liver cancer therapy in clinical medicine. PMID:26833548

  19. nanoparticles

    NASA Astrophysics Data System (ADS)

    Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J. Enrique

    2014-10-01

    Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.

  20. In Vitro Biocompatibility and Antibacterial Efficacy of a Degradable Poly(L-lactide-co-epsilon-caprolactone) Copolymer Incorporated with Silver Nanoparticles

    PubMed Central

    Samberg, Meghan E.; Mente, Peter; He, Ting; King, Martin W.; Monteiro-Riviere, Nancy A.

    2014-01-01

    Silver nanoparticles (Ag-nps) are currently used as a natural biocide to prevent undesired bacterial growth in clothing, cosmetics and medical products. The objective of the study was to impart antibacterial properties through the incorporation of Ag-nps at increasing concentrations to electrospun degradable 50:50 poly(L-lactide-co-epsilon-caprolactone) scaffolds for skin tissue engineering applications. The biocompatibility of the scaffolds containing Ag-nps was evaluated with human epidermal keratinocytes (HEK); cell viability and proliferation were evaluated using Live/Dead and alamarBlue viability assays following 7 and 14 days of cell culture on the scaffolds. Significant decreases in cell viability and proliferation were noted for the 1.0 mg(Ag) g(scaffold)−1 after 7 and 14 days on Ag-nps scaffolds. After 14 days, scanning electron microscopy revealed a confluent layer of HEK on the surface of the 0.0 and 0.1 mg(Ag) g(scaffold)−1. Both 0.5 and 1.0 mg(Ag) g(scaffold)−1 were capable of inhibiting both Gram positive and negative bacterial strains. Uniaxial tensile tests revealed a significant (p < 0.001) decrease in the modulus of elasticity following Ag-nps incorporation compared to control. These findings suggest that a scaffold containing between 0.5 and 1.0 mg(Ag) g(scaffold)−1 is both biocompatible and antibacterial, and is suitable for skin tissue engineering graft scaffolds. PMID:24150238

  1. In vitro biocompatibility and antibacterial efficacy of a degradable poly(L-lactide-co-epsilon-caprolactone) copolymer incorporated with silver nanoparticles.

    PubMed

    Samberg, Meghan E; Mente, Peter; He, Ting; King, Martin W; Monteiro-Riviere, Nancy A

    2014-07-01

    Silver nanoparticles (Ag-nps) are currently used as a natural biocide to prevent undesired bacterial growth in clothing, cosmetics and medical products. The objective of the study was to impart antibacterial properties through the incorporation of Ag-nps at increasing concentrations to electrospun degradable 50:50 poly(L-lactide-co-epsilon-caprolactone) scaffolds for skin tissue engineering applications. The biocompatibility of the scaffolds containing Ag-nps was evaluated with human epidermal keratinocytes (HEK); cell viability and proliferation were evaluated using Live/Dead and alamarBlue viability assays following 7 and 14 days of cell culture on the scaffolds. Significant decreases in cell viability and proliferation were noted for the 1.0 mg(Ag) g(scaffold)(-1) after 7 and 14 days on Ag-nps scaffolds. After 14 days, scanning electron microscopy revealed a confluent layer of HEK on the surface of the 0.0 and 0.1 mg(Ag) g(scaffold)(-1). Both 0.5 and 1.0 mg(Ag) g(scaffold)(-1) were capable of inhibiting both Gram positive and negative bacterial strains. Uniaxial tensile tests revealed a significant (p < 0.001) decrease in the modulus of elasticity following Ag-nps incorporation compared to control. These findings suggest that a scaffold containing between 0.5 and 1.0 mg(Ag) g(scaffold)(-1) is both biocompatible and antibacterial, and is suitable for skin tissue engineering graft scaffolds. PMID:24150238

  2. Bactericidal block copolymer micelles.

    PubMed

    Vyhnalkova, Renata; Eisenberg, Adi; van de Ven, Theo

    2011-05-12

    Block copolymer micelles with bactericidal properties were designed to deactivate pathogens such as E. coli bacteria. The micelles of PS-b-PAA and PS-b-P4VP block copolymers were loaded with biocides TCMTB or TCN up to 20 or 30 wt.-%, depending on the type of antibacterial agent. Bacteria were exposed to loaded micelles and bacterial deactivation was evaluated. The micelles loaded with TCN are bactericidal; bacteria are killed in less than two minutes of exposure. The most likely interpretation of the data is that the biocide is transferred to the bacteria by repeated micelle/bacteria contacts, and not via the solution. PMID:21275041

  3. Self-assembly of a series of random copolymers bearing amphiphilic side chains.

    PubMed

    Wu, Xu; Qiao, Yingjie; Yang, Hui; Wang, Jinben

    2010-09-15

    A novel series of comb-like random copolymers were prepared by polymerization of amphiphilic macromonomers, 2-(acrylamido)-octane sulfonic acid (AMC(8)S), 2-(acrylamido)-dodecane sulfonic acid (AMC(12)S), and 2-(acrylamido)-hexadecane sulfonic acid (AMC(16)S), with 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS) respectively. The synthesis of the polymers with the same contents of amphiphilic units as side chains, but different chain length, enabled us to study the chain length dependence of their association in salt solution. Steady-state fluorescence measurements with pyrene as a polarity probe, quasielastic light scattering techniques (QELS) and transmission electron micrograph (TEM) were employed to investigate the associative properties of the system. The above investigations showed that all kinds of side chains begin to assemble at certain polymer concentrations and the critical aggregation concentration (CAC) decrease dramatically with the increase in the length and content of alkyl. An interesting phenomenon is that the assembly tends more favorably to occur among different molecules rather than within single molecule when the number of carbon atoms in the alkyl groups or the polymer concentration increases, leading to the formation of larger multimolecular micelle-like aggregate. The aim of the present work is to establish the fundamental preconditions of intramolecular and intermolecular association fashions for the polymers, which is useful for the exploitation of functional groups and contributes to the development of amphiphilic random polymers. PMID:20576273

  4. Patterned silica films using microphase separation of a block copolymer

    NASA Astrophysics Data System (ADS)

    Kataoka, Sho; Takeuchi, Yasutaka; Endo, Akira

    2014-11-01

    Block copolymers exhibit various nanoscale ordered morphologies induced by microphase separation. Here, we present a method for providing two types of patterned silica films on Si wafer substrates simply by shifting the phase equilibrium of a block copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-P4VP). In this method, siloxane is adsorbed onto poly(4-vinylpyridine) blocks of PS-P4VP whose structure varies with solvent polarity and is calcined to remove the block copolymer. Siloxane is in a dispersed phase with toluene as a solvent resulting in silica nanoparticle arrays, while siloxane is in a continuous phase with N, N-dimethylformamide (DMF) resulting in silica films with ordered mesopores. Since the pore size of silica films prepared in DMF is approximately 20 nm, the film has the ability to serve as a support for enzymes such as laccase.

  5. Field-Based Simulations of Confined Block Copolymers

    NASA Astrophysics Data System (ADS)

    Fredrickson, Glenn

    2009-03-01

    This presentation will discuss field-theoretic simulation methods that can be used to analyze the self-assembly behavior of thin block copolymer films, including films that are laterally confined on a flat substrate and curved films on a spherical manifold. Our studies of lateral confinement have revealed strategies for epitaxially templating microdomain patterns with long-range in-plane order and minimal defects (``graphoepitaxy"), and methods for diversifying the set of stable 2D lattice structures. On the sphere, we have found defective ground state block copolymer morphologies that are analogous to spherical crystalline packings in other contexts, e.g. the Thompson problem and viruses. The methods and findings have applications in block copolymer lithography and in dispersion technology of polymer-stabilized nanoparticles and colloids.

  6. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G.; Matzger, Adam J.; Benin, Annabelle I.; Willis, Richard R.

    2012-12-04

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  7. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2012-11-13

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  8. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2014-11-11

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  9. Ultraviolet absorbing copolymers

    DOEpatents

    Gupta, Amitava; Yavrouian, Andre H.

    1982-01-01

    Photostable and weather stable absorping copolymers have been prepared from acrylic esters such as methyl methacrylate containing 0.1 to 5% of an 2-hydroxy-allyl benzophenone, preferably the 4,4' dimethoxy derivative thereof. The pendant benzophenone chromophores protect the acrylic backbone and when photoexcited do not degrade the ester side chain, nor abstract hydrogen from the backbone.

  10. Observation of two different fractal structures in nanoparticle, protein and surfactant complexes

    SciTech Connect

    Mehan, Sumit Kumar, Sugam Aswal, V. K.

    2014-04-24

    Small angle neutron scattering has been carried out from a complex of nanoparticle, protein and surfactant. Although all the components are similarly (anionic) charged, we have observed strong interactions in their complex formation. It is characterized by the coexistence of two different mass fractal structures. The first fractal structure is originated from the protein and surfactant interaction and second from the depletion effect of first fractal structure leading the nanoparticle aggregation. The fractal structure of protein-surfactant complex represents to bead necklace structure of micelle-like clusters of surfactant formed along the unfolded protein chain. Its fractal dimension depends on the surfactant to protein ratio (r) and decreases with the increase in r. However, fractal dimension of nanoparticle aggregates in nanoparticle-protein complex is found to be independent of protein concentration and governed by the diffusion limited aggregation like morphology.

  11. Observation of two different fractal structures in nanoparticle, protein and surfactant complexes

    NASA Astrophysics Data System (ADS)

    Mehan, Sumit; Kumar, Sugam; Aswal, V. K.

    2014-04-01

    Small angle neutron scattering has been carried out from a complex of nanoparticle, protein and surfactant. Although all the components are similarly (anionic) charged, we have observed strong interactions in their complex formation. It is characterized by the coexistence of two different mass fractal structures. The first fractal structure is originated from the protein and surfactant interaction and second from the depletion effect of first fractal structure leading the nanoparticle aggregation. The fractal structure of protein-surfactant complex represents to bead necklace structure of micelle-like clusters of surfactant formed along the unfolded protein chain. Its fractal dimension depends on the surfactant to protein ratio (r) and decreases with the increase in r. However, fractal dimension of nanoparticle aggregates in nanoparticle-protein complex is found to be independent of protein concentration and governed by the diffusion limited aggregation like morphology.

  12. Dynamics of Block Copolymer Nanocomposites

    SciTech Connect

    Mochrie, Simon G. J.

    2014-09-09

    A detailed study of the dynamics of cadmium sulfide nanoparticles suspended in polystyrene homopolymer matrices was carried out using X-ray photon correlation spectroscopy for temperatures between 120 and 180 °C. For low molecular weight polystyrene homopolymers, the observed dynamics show a crossover from diffusive to hyper-diffusive behavior with decreasing temperatures. For higher molecular weight polystyrene, the nanoparticle dynamics appear hyper-diffusive at all temperatures studied. The relaxation time and characteristic velocity determined from the measured hyper-diffusive dynamics reveal that the activation energy and underlying forces determined are on the order of 2.14 × 10-19 J and 87 pN, respectively. We also carried out a detailed X-ray scattering study of the static and dynamic behavior of a styrene– isoprene diblock copolymer melt with a styrene volume fraction of 0.3468. At 115 and 120 °C, we observe splitting of the principal Bragg peak, which we attribute to phase coexistence of hexagonal cylindrical and cubic double- gyroid structure. In the disordered phase, above 130 °C, we have characterized the dynamics of composition fluctuations via X-ray photon correlation spectroscopy. Near the peak of the static structure factor, these fluctuations show stretched-exponential relaxations, characterized by a stretching exponent of about 0.36 for a range of temperatures immediately above the MST. The corresponding characteristic relaxation times vary exponentially with temperature, changing by a factor of 2 for each 2 °C change in temperature. At low wavevectors, the measured relaxations are diffusive with relaxation times that change by a factor of 2 for each 8 °C change in temperature.

  13. Theory of the Miscibility of Fullerenes in Random Copolymer Melts

    SciTech Connect

    Dadmun, Mark D; Sumpter, Bobby G; Schweizer, Kenneth; Banerjee, Debapriya

    2013-01-01

    We combine polymer integral equation theory and computational chemistry methods to study the interfacial structure, effective interactions, miscibility and spatial dispersion mechanism of fullerenes dissolved in specific random AB copolymer melts characterized by strong non-covalent electron donor-acceptor interactions with the nanofiller. A statistical mechanical basis is developed for designing random copolymers to optimize fullerene dispersion at intermediate copolymer compositions. Pair correlation calculations reveal a strong sensitivity of interfacial packing near the fullerene to copolymer composition and adsorption energy mismatch. The potential of mean force between fullerenes displays rich trends, often non-monotonic with copolymer composition, reflecting a non-additive competition between direct filler attractions and polymer-mediated bridging and steric stabilization. The spinodal phase diagrams are in qualitative agreement with recent solubility limit experimental observations on three systems, and testable predictions are made for other random copolymers. The distinctive non-monotonic variation of miscibility with copolymer composition is found to be primarily a consequence of composition-dependent, spatially short-range attractions between the A and B monomers with the fullerene. A remarkably rich, polymer-specific temperature dependence of the spinodal diagram is predicted which reflects the thermal sensitivity of spatial correlations which can result in fullerene miscibility either increasing or decreasing with cooling. The calculations are contrasted with a simpler effective homopolymer model and the random structure Flory-Huggins model. The former appears to be qualitatively reasonable but can incur large quantitative errors since it misses preferential packing of monomers near nanoparticles, while the latter appears to fail qualitatively due to its neglect of all spatial correlations.

  14. Development of polymeric–cationic peptide composite nanoparticles, a nanoparticle-in-nanoparticle system for controlled gene delivery

    PubMed Central

    Jain, Arvind K; Massey, Ashley; Yusuf, Helmy; McDonald, Denise M; McCarthy, Helen O; Kett, Vicky L

    2015-01-01

    We report the formulation of novel composite nanoparticles that combine the high transfection efficiency of cationic peptide-DNA nanoparticles with the biocompatibility and prolonged delivery of polylactic acid–polyethylene glycol (PLA-PEG). The cationic cell-penetrating peptide RALA was used to condense DNA into nanoparticles that were encapsulated within a range of PLA-PEG copolymers. The composite nanoparticles produced exhibited excellent physicochemical properties including size <200 nm and encapsulation efficiency >80%. Images of the composite nanoparticles obtained with a new transmission electron microscopy staining method revealed the peptide-DNA nanoparticles within the PLA-PEG matrix. Varying the copolymers modulated the DNA release rate >6 weeks in vitro. The best formulation was selected and was able to transfect cells while maintaining viability. The effect of transferrin-appended composite nanoparticles was also studied. Thus, we have demonstrated the manufacture of composite nanoparticles for the controlled delivery of DNA. PMID:26648722

  15. Controlling block copolymer phase behavior using ionic surfactant

    NASA Astrophysics Data System (ADS)

    Ray, D.; Aswal, V. K.

    2016-05-01

    The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO26PO39EO26)] in presence of anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution as a function of temperature has been studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactants. Each of the individual components (block copolymer and surfactant) and the nanoparticle-surfactant mixed system have been examined at varying temperature. The block copolymer P85 forms spherical micelles at room temperature whereas shows sphere-to-rod like micelle transition at higher temperatures. On the other hand, SDS surfactant forms ellipsoidal micelles over a wide temperature range. Interestingly, it is found that phase behavior of mixed micellar system (P85 + SDS) as a function of temperature is drastically different from that of P85, giving the control over the temperature-dependent phase behavior of block copolymers.

  16. Controlling sub-microdomain structure in microphase-ordered block copolymers and their nanocomposites

    NASA Astrophysics Data System (ADS)

    Bowman, Michelle Kathleen

    poly(styrene-b-methyl methacrylate) (SM) diblock copolymer with an order-disorder transition temperature (TODT) of 186°C, we find that the addition of clustered and discrete nanoparticles of varying size and surface selectivity can cause T ODT to generally decrease, but occasionally increase. Also experimenting with a poly(styrene-b-isoprene) (SI) diblock copolymer with an TODT of 116°C, we find that the addition of smaller nanoparticles at small volume fractions effect the TODT more profoundly. The latter unexpected results are likewise predicted by SCFT and provide a unique strategy by which to improve the nanostructure stability of block copolymers by physical means.

  17. Imide/arylene ether copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J. (Inventor); Hergenrother, Paul M. (Inventor); Bass, Robert G. (Inventor)

    1992-01-01

    Imide/arylene ether block copolymers are prepared by reacting anhydride terminated poly(amic acids) with amine terminated poly(arylene ethers) in polar aprotic solvents and by chemically or thermally cyclodehydrating the resulting intermediate poly(amic acids). The resulting block copolymers have one glass transition temperature or two, depending upon the particular structure and/or the compatibility of the block units. Most of these block copolymers form tough, solvent resistant films with high tensile properties.

  18. Block copolymer battery separator

    DOEpatents

    Wong, David; Balsara, Nitash Pervez

    2016-04-26

    The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.

  19. Adsorption and desorption phenomena of PEO-PPO-PEO triblock copolymer systems on model surfaces

    NASA Astrophysics Data System (ADS)

    Brandani, Pietro

    This thesis reports on the kinetic and equilibrium behavior for the adsorption from solution of a family of copoly(ethyleneoxide-propyleneoxide-ethyleneoxide), PEO-PPO-PEO, triblock copolymers on gold surfaces modified by a methyl terminated self-assembled monolayer of a long chain alkanethiol (CH3(CH 2)10SH) and by a long chain mercaptoalkanoic acid (HOOC(CH 2)10SH). Events at the surface were monitored with a surface plasmon resonance technique with a high time resolution (0.1 s). Atomic force microscopy (AFM) in the liquid environment was conducted on a selected number of cases to discern the morphology of the copolymer coated surfaces. The data were analyzed in the context a mass transfer corrected Langmuir kinetics model. The model is only able to reproduce the observations for very dilute solutions, or for the initial stages of the process, but it allows to better discriminate the onset of the different mechanisms of adsorption. For the hydrophobic surface, the adsorbed amounts go through a maximum near the critical micelle concentration (CMC) and thus the process is not consistent with a Langmuir isotherm; in addition we the process is partially irreversible. The kinetics show that, for a series of compounds with the same length of the PPO block, the character of the adsorption process is affected by the relative balance of the hydrophilic and hydrophobic content within the copolymer: higher hydrophobic content leads to enhanced adsorption rates past the CMC. AFM observations confirm that globular micelle-like aggregates are present at the surface for the more hydrophobic species. In contrast, a uniform monolayer-like morphology is observed for the more hydrophilic species. For the hydrophilic surface, it is again found that the adsorbed amounts go through a maximum near the critical micelle concentration (CMC), however, in this case, the process is reversible. Enhanced adsorption rates past the CMC are observed irrespective of the relative balance of the

  20. Partial Miscibility in Copolymer Blends

    NASA Astrophysics Data System (ADS)

    Clark, Elizabeth; Lipson, Jane

    2011-03-01

    Copolymers can be used to affect the miscibility of otherwise immiscible polymer blends by acting as compatibilizers. To better understand the energetics of these types of systems, we use a simple lattice model to study phase separation in binary copolymer/homopolymer blends. We focus on a copolymer that contains both A and B type monomers and a homopolymer that contains purely A type monomer. An example of a system that we are investigating is polyethylene mixed with either random or alternating poly(ethylene-co-propylene). The sequence effect on miscibility as the copolymer microstructure is varied from random to alternating is investigated as well. The support of GAANN is gratefully acknowledged.

  1. Imide/Arylene Ether Copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Hergenrother, Paul M.; Bass, Robert G.

    1991-01-01

    New imide/arylene ether copolymers prepared by reacting anhydride-terminated poly(amic acids) with amine-terminated poly(arylene ethers) in polar aprotic solvents. Each resulting copolymer may have one glass-transition temperature or two, depending on chemical structure and/or compatibility of block units. Most of copolymers form tough, solvent-resistant films with high tensile properties. Films cast from solution tough and flexible, and exhibit useful thermal and mechanical properties. Potentially useful as moldings, adhesives, or composite matrices. Because of flexible arylene ether blocks, these copolymers easier to process than polyimides.

  2. Ferromagnetic resonance spectroscopy of carboxylated cobalt-containing nanocomposite ethyl methacrylate/acrylic acid copolymers

    NASA Astrophysics Data System (ADS)

    Voytsihovskaya, S. A.; Sokolov, M. E.; Panyushkin, V. T.; Gromov, P. Yu.; Shcherbina, A. A.; Matveev, V. V.

    2013-01-01

    We have used ferromagnetic resonance spectroscopy to study the effect of the concentration of cobalt nanoparticles (5-9 nm) incorporated into ethyl methacrylate/acrylic acid copolymers (monomer ratios 100:1 and 10:1) on the magnitude of the resonant field in ferromagnetic resonance and on the effective magnetization of thin-film samples of these nanocomposite polymer materials. The cobalt nanoparticles were obtained by thermolysis of Co2(CO)8 in 5% solutions of the indicated copolymers in toluene. From the solutions obtained, we prepared films of thickness 1 μm on aluminum substrates.

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

    PubMed

    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. PMID:25811763

  4. Polyether/Polyester Graft Copolymers

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L., Jr.; Wakelyn, N.; Stoakley, D. M.; Proctor, K. M.

    1986-01-01

    Higher solvent resistance achieved along with lower melting temperature. New technique provides method of preparing copolymers with polypivalolactone segments grafted onto poly (2,6-dimethyl-phenylene oxide) backbone. Process makes strong materials with improved solvent resistance and crystalline, thermally-reversible crosslinks. Resulting graft copolymers easier to fabricate into useful articles, including thin films, sheets, fibers, foams, laminates, and moldings.

  5. Poly(ethylene glycol) grafted chitosan as new copolymer material for oral delivery of insulin

    NASA Astrophysics Data System (ADS)

    Ho, Thanh Ha; Thanh Le, Thi Nu; Nguyen, Tuan Anh; Chien Dang, Mau

    2015-09-01

    A new scheme of grafting poly (ethylene glycol) onto chitosan was proposed in this study to give new material for delivery of insulin over oral pathway. First, methoxy poly(ethylene glycol) amine (mPEGa MW 2000) were grafted onto chitosan (CS) through multiples steps to synthesize the grafting copolymer PEG-g-CS. After each synthesis step, chitosan and its derivatives were characterized by FTIR, 1H NMR Then, insulin loaded PEG-g-CS nanoparticles were prepared by cross-linking of CS with sodium tripolyphosphate (TPP). Same insulin loaded nanoparticles using unmodified chitosan were also prepared in order to compare with the modified ones. Results showed better protecting capacity of the synthesized copolymer over original CS. CS nanoparticles (10 nm of size) were gel like and high sensible to temperature as well as acidic environment while PEG-g-CS nanoparticles (200 nm of size) were rigid and more thermo and pH stable.

  6. Assembly of Double-Hydrophilic Block Copolymers Triggered by Gadolinium Ions: New Colloidal MRI Contrast Agents.

    PubMed

    Frangville, Camille; Li, Yichen; Billotey, Claire; Talham, Daniel R; Taleb, Jacqueline; Roux, Patrick; Marty, Jean-Daniel; Mingotaud, Christophe

    2016-07-13

    Mixing double-hydrophilic block copolymers containing a poly(acrylic acid) block with gadolinium ions in water leads to the spontaneous formation of polymeric nanoparticles. With an average diameter near 20 nm, the nanoparticles are exceptionally stable, even after dilution and over a large range of pH and ionic strength. High magnetic relaxivities were measured in vitro for these biocompatible colloids, and in vivo magnetic resonance imaging on rats demonstrates the potential utility of such polymeric assemblies. PMID:27224089

  7. Non-equilibrium self-assembly of metals on diblock copolymer templates

    NASA Astrophysics Data System (ADS)

    Lopes, Ward Antone

    Typically, the most perfectly ordered, self-assembled structures correspond to equilibrium states of the system. Here, I show that a high degree of order can arise out of strongly non-equilibrium conditions. I report on a systematic study of non-equilibrium aspects of the decoration of diblock copolymer ultrathin films by evaporated metals. I observe two distinct behaviors for selectively decorating the diblock copolymer: either the metal decorates the diblock copolymer template with nanoparticles or the metal decorates the template with nanowires. Remarkably, these nanowires remain stable under non-equilibrium conditions. I focus on results obtained with evaporated gold and silver on asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA). Gold and a number of other metals (indium, tin, lead, bismuth, aluminum) decorate the diblock copolymer with chains of nanoparticles and don't form wires. Silver forms chains of nanoparticles at low coverage (<30 A), but at high coverage (>100 A), silver forms nanowires. One can understand the formation of the chains of nanoparticles by understanding the equilibrium state of the system (metal + polymer). The silver nanowires, however, are highly non-equilibrium structures. To understand their formation, I modeled the self-assembly of the nanowires with a Monte Carlo simulation. This Monte Carlo simulation qualitatively agrees with the formation of the silver nanowires and their relaxation to equilibrium upon moderate heating.

  8. Colouring crystals with inorganic nanoparticles.

    PubMed

    Kulak, Alexander N; Yang, Pengcheng; Kim, Yi-Yeoun; Armes, Steven P; Meldrum, Fiona C

    2014-01-01

    A simple, one-pot method is presented whereby gold nanoparticles coated with a zwitterionic diblock copolymer are incorporated within single crystals of calcite. This may provide a versatile alternative to dyeing crystal with organic molecules and could be extended to create a series of new nanocomposite crystals with novel properties. PMID:24202647

  9. Synthesis and characterization of thermoresponsive copolymers for drug delivery.

    PubMed

    Aerry, Swati; De, Arnab; Kumar, Ajeet; Saxena, Amit; Majumdar, D K; Mozumdar, Subho

    2013-07-01

    We report the synthesis and characterization of two nontoxic, thermogelling drug delivery systems which are liquid at room temperatures but become a gel at physiological temperature (37°C) potentially leading to release of a drug molecule. We selected temperature as the stimulus for drug release as it is physiologically invariant. A free radical polymerization of N-isopropylacrylamide (NIPAM) and N-vinylpyrrolidone (VP) was carried out under nitrogen atmosphere in double-distilled water at two different temperatures (30°C and 70°C), and the copolymers obtained were characterized by various analytical techniques. The molar ratios of the two monomers were altered with increasing NIPAM content and their cloud point temperature or least critical solution temperature (LCST) was determined. The copolymer at 9:1 ratio of NIPAM to VP resulted in the formation of nanoparticle-based gel (NG1) at 30°C; however, at 70°C, a microgel (MG1) was formed. The LCST of the nanogel and microgel was 33.5-34°C and 36.5-37°C, respectively. Thus, both the copolymers are water soluble at room temperature, but distinct phases appear at physiological temperatures. We hypothesized that these copolymers on entrapment with a drug could be used for topical application to the skin or eye for controlled drug delivery applications. Toxicological studies revealed that the copolymers are nontoxic in HeLa cells. Finally, our experiments show that a model drug [bovine serum albumin (BSA)] is released at 37°C with zero-order kinetics and confirmed using multiple well-known mathematical models. PMID:23255175

  10. Polymer Functionalized Nanoparticles in Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Jayaraman, Arthi

    2013-03-01

    Significant interest has grown around the ability to control spatial arrangement of nanoparticles in a polymer nanocomposite to engineer materials with target properties. Past work has shown that one could achieve controlled assembly of nanoparticles in the polymer matrix by functionalizing nanoparticle surfaces with homopolymers. This talk will focus on our recent work using Polymer Reference Interaction Site Model (PRISM) theory and Monte Carlo simulations and GPU-based molecular dynamics simulations to specifically understand how heterogeneity in the polymer functionalization in the form of a) copolymers with varying monomer chemistry and monomer sequence, and b) polydispersity in homopolymer grafts can tune effective interactions between functionalized nanoparticles, and the assembly of functionalized nanoparticles.

  11. Self-assembly of ABC triblock copolymers under 3D soft confinement: a Monte Carlo study.

    PubMed

    Yan, Nan; Zhu, Yutian; Jiang, Wei

    2016-01-21

    Under three-dimensional (3D) soft confinement, block copolymers can self-assemble into unique nanostructures that cannot be fabricated in an un-confined space. Linear ABC triblock copolymers containing three chemically distinct polymer blocks possess relatively complex chain architecture, which can be a promising candidate for the 3D confined self-assembly. In the current study, the Monte Carlo technique was applied in a lattice model to study the self-assembly of ABC triblock copolymers under 3D soft confinement, which corresponds to the self-assembly of block copolymers confined in emulsion droplets. We demonstrated how to create various nanostructures by tuning the symmetry of ABC triblock copolymers, the incompatibilities between different block types, and solvent properties. Besides common pupa-like and bud-like nanostructures, our simulations predicted various unique self-assembled nanostructures, including a striped-pattern nanoparticle with intertwined A-cages and C-cages, a pyramid-like nanoparticle with four Janus B-C lamellae adhered onto its four surfaces, an ellipsoidal nanoparticle with a dumbbell-like A-core and two Janus B-C lamellae and a Janus B-C ring surrounding the A-core, a spherical nanoparticle with a A-core and a helical Janus B-C stripe around the A-core, a cubic nanoparticle with a cube-shape A-core and six Janus B-C lamellae adhered onto the surfaces of the A-cube, and a spherical nanoparticle with helical A, B and C structures, from the 3D confined self-assembly of ABC triblock copolymers. Moreover, the formation mechanisms of some typical nanostructures were also examined by the variations of the contact numbers with time and a series of snapshots at different Monte Carlo times. It is found that ABC triblock copolymers usually aggregate into a loose aggregate at first, and then the microphase separation between A, B and C blocks occurs, resulting in the formation of various nanostructures. PMID:26571300

  12. Superparamagnetic-oil-filled nanocapsules of a ternary graft copolymer.

    PubMed

    Miao, Lei; Liu, Feng; Lin, Shudong; Hu, Jiwen; Liu, Guojun; Yang, Yang; Tu, Yuanyuan; Hou, Chengmin; Li, Fei; Hu, Meilong; Luo, Hongsheng

    2014-04-15

    Stearic and oleic acid-coated Fe3O4 nanoparticles were dispersed in decahydronaphthalene (DN). This oil phase was dispersed in water using ternary graft copolymer poly(glycidyl methacrylate)-graft-[polystyrene-ran-(methoxy polyethylene glycol)-ran-poly(2-cinnamoyloxyethyl methacrylate)] or PGMA-g-(PS-r-MPEG-r-PCEMA) to yield capsules. The walls of these capsules were composed of PCEMA chains that were soluble in neither water nor DN, and the DN-soluble PS chains stretched into the droplet phase and the water-soluble MPEG chains extended into the aqueous phase. Structurally stable capsules were prepared by photolyzing the capsules with UV light to cross-link the PCEMA layer. Both the magnetite particles and the magnetite-containing capsules were superparamagnetic. The sizes of the capsules increased as they were loaded with more magnetite nanoparticles, reaching a maximal loading of ~0.5 mg of ligated magnetite nanoparticles per mg of copolymer. But the radii of the capsules were always <100 nm. Thus, a novel nanomaterial--superparamagnetic-oil-filled polymer nanocapsules--was prepared. The more heavily loaded capsules were readily captured by a magnet and could be redispersed via shaking. Although the cross-linked capsules survived this capturing and redispersing treatment many times, the un-cross-linked capsules ruptured after four cycles. These results suggest the potential to tailor-make capsules with tunable wall stability for magnetically controlled release applications. PMID:24684287

  13. Hemocompatibility of folic-acid-conjugated amphiphilic PEG-PLGA copolymer nanoparticles for co-delivery of cisplatin and paclitaxel: treatment effects for non-small-cell lung cancer.

    PubMed

    He, Zelai; Shi, Zengfang; Sun, Wenjie; Ma, Jing; Xia, Junyong; Zhang, Xiangyu; Chen, Wenjun; Huang, Jingwen

    2016-06-01

    In this study, we used folic-acid-modified poly(ethylene glycol)-poly(lactic-co-glycolic acid) (FA-PEG-PLGA) to encapsulate cisplatin and paclitaxel (separately or together), and evaluated their antitumor effects against lung cancer; this study was conducted in order to investigate the antitumor effects of the co-delivery of cisplatin and paclitaxel by a targeted drug delivery system. Blood compatibility assays and complement activation tests revealed that FA-PEG-PLGA nanoparticles did not induce blood hemolysis, blood clotting, or complement activation. The results also indicated that FA-PEG-PLGA nanoparticles had no biotoxic effects, the drug delivery system allowed controlled release of the cargo molecules, and the co-delivery of cisplatin and paclitaxel efficiently induces cancer cell apoptosis and cell cycle retardation. In addition, co-delivery of cisplatin and paclitaxel showed the ability to suppress xenograft lung cancer growth and prolong the survival time of xenografted mice. These results implied that FA-PEG-PLGA nanoparticles can function as effective carriers of cisplatin and paclitaxel, and that co-delivery of cisplatin and paclitaxel by FA-PEG-PLGA nanoparticles results in more effective antitumor effects than the combination of free-drugs or single-drug-loaded nanoparticles. PMID:26695149

  14. Imide/arylene ether copolymers. I

    NASA Technical Reports Server (NTRS)

    Jensen, B. J.; Hergenrother, P. M.; Bass, R. G.

    1991-01-01

    The preparation of a series of novel imide/arylene ether copolymers is described together with the results of viscosity and DSC Tg(Tm) measurements. The copolymers were synthesized from an arylene ether block and either an amorphous or semicrystalline imide block. One block copolymer was end-capped, and the molecular weight was controlled to improve compression moldability. The paper also presents results of mechanical properties tests on copolymer samples.

  15. Molecular Dynamics Simulations of Silica-Filled Copolymers with Variable Sequence for Applications in Tire Treads

    NASA Astrophysics Data System (ADS)

    Trazkovich, Alex J.; Hall, Lisa M.

    We simulate a simple nanocomposite relevant to tire tread compounds consisting of a single spherical nanoparticle surrounded by coarse-grained polymer chains. The polymers are composed of two different monomer types, which have different interaction strengths with the nanoparticle. The monomer sequence can be varied to model different copolymer configurations. We study the polymer end-to-end vector autocorrelation functions to obtain relaxation times of adsorbed and bulk polymer, showing how the interphase is affected by the polymer type and the monomer-nanoparticle interaction strengths. An understanding of the effect of copolymer sequence on the range of the polymer interphase and the magnitude of the effect on chain dynamics is critical to tire tread material design since the primary polymer component of modern tire tread is styrene-butadiene rubber (SBR) copolymer, which may be synthesized in primarily random or in various blocky copolymer configurations. Macromolecular adsorption to and desorption from filler surfaces has a significant effect on hysteresis, and in tire treads, hysteresis must be controlled to optimize the tradeoff between traction and rolling resistance. Superior tire tread materials must have high hysteresis under the operating conditions of traction while maintaining low hysteresis under the operating conditions of rolling resistance. An opportunity exists to control hysteresis through the use of SBR with specific monomer sequences.

  16. Magnetic silica hybrids modified with guanidine containing co-polymers for drug delivery applications.

    PubMed

    Timin, Alexander S; Khashirova, Svetlana Yu; Rumyantsev, Evgeniy V; Goncharenko, Alexander A

    2016-07-01

    Guanidine containing co-polymers grafted onto silica nanoparticles to form core-shell structure were prepared by sol-gel method in the presence of γ-Fe2O3 nanoparticles. The morphological features for uncoated and coated silica particles have been characterized with scanning electron microscopy. The results show that the polymer coated silicas exhibit spherical morphology with rough polymeric surface covered by γ-Fe2O3 nanoparticles. The grafting amount of guanidine containing co-polymers evaluated by thermogravimetric analysis was in the range from 17 to 30%. Then, the drug loading properties and cumulative release of silica hybrids modified with guanidine containing co-polymers were evaluated using molsidomine as a model drug. It was shown that after polymer grafting the loading content of molsidomine could reach up to 3.42±0.21 and 2.34±0.14mg/g respectively. The maximum drug release of molsidomine is achieved at pH1.6 (approximately 71-75% release at 37°C), whereas at pH7.4 drug release is lower (50.4-59.6% release at 37°C). These results have an important implication that our magneto-controlled silica hybrids modified with guanidine containing co-polymers are promising as drug carriers with controlled behaviour under influence of magnetic field. PMID:27127024

  17. Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.

    PubMed

    Worm, Matthias; Kang, Biao; Dingels, Carsten; Wurm, Frederik R; Frey, Holger

    2016-05-01

    Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand." PMID:27000789

  18. Fractionation of salivary micelle-like structures by gel chromatography.

    PubMed

    Rykke, M; Young, A; Devold, T; Smistad, G; Rölla, G

    1997-10-01

    Globular structures have been demonstrated in human parotid saliva by transmission electron microscopy and photon correlation spectroscopy. The aim of this study was to fractionate these salivary globular structures for analytical and preparative purposes using a gel-filtration material capable of separating spherical particles up to 300-400 nm in diameter. Freshly obtained parotid saliva was applied to a Sephacryl S-1000 column. Peak fractions were collected and prepared for transmission electron microscopy (TEM) or for amino acid analysis. Bovine milk was included as the casein micelles by TEM appear to be similar to the salivary aggregates and their elution profiles are known. The salivary globular structures were eluted in one major peak. TEM of negatively stained samples from the peak fractions demonstrated globular protein aggregates consistent with the salivary structures in parotid saliva. Amino acid analysis showed characteristic amino acid profiles with unusual high levels of proline, 40-45%. The casein micelles were eluted in one major peak and separated from the whey proteins. This study indicates that the salivary globular structures can be isolated by gel chromatography. The amino acid analysis indicates that proline-rich proteins may be an important fraction of the salivary globular structures. PMID:9395115

  19. Copolymers For Capillary Gel Electrophoresis

    DOEpatents

    Liu, Changsheng; Li, Qingbo

    2005-08-09

    This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

  20. A slow-release system of bacterial cellulose gel and nanoparticles for hydrophobic active ingredients.

    PubMed

    Numata, Yukari; Mazzarino, Leticia; Borsali, Redouane

    2015-01-01

    A combination of bacterial cellulose (BC) gel and amphiphilic block copolymer nanoparticles was investigated as a drug delivery system (DDS) for hydrophobic active ingredients. Poly(ethylene oxide)-b-poly(caprolactone) (PEO-b-PCL) and retinol were used as the block copolymer and hydrophobic active ingredient, respectively. The BC gel was capable of incorporating copolymer nanoparticles and releasing them in an acetic acid-sodium acetate buffer solution (pH 5.2) at 37 °C. The percentage of released copolymer reached a maximum value of approximately 60% after 6h and remained constant after 24h. The percentage of retinol released from the copolymer-containing BC gel reached a maximum value at 4h. These results show that the combination of BC gel and nanoparticles is a slow-release system that may be useful in the cosmetic and biomedical fields for skin treatment and preparation. PMID:25840273

  1. Emulsifying properties of biodegradable polylactide-grafted dextran copolymers.

    PubMed

    Raynaud, J; Choquenet, B; Marie, E; Dellacherie, E; Nouvel, C; Six, J-L; Durand, A

    2008-03-01

    Amphiphilic glycopolymers, polylactide-grafted dextran copolymers (Dex-g-PLA), were synthesized with a well-controlled architecture obtained through a three-step procedure: partial silylation of the dextran hydroxyl groups, ring-opening polymerization of D,L-lactide initiated from remaining hydroxyl groups, silylether deprotection under very mild conditions. Depending on their proportion in polylactide (PLA), these copolymers exhibited solubility either in water or in organic solvents. The emulsifying properties of these glycopolymers were studied: depending on their PLA-to-dextran ratio, they were able to stabilize either direct or inverse emulsions. Droplet size was related to the amount of amphiphilic copolymer in the continuous phase. The aging mechanism of both direct and inverse emulsions was shown to be Ostwald ripening in the first weeks following preparation. Finally inverse miniemulsion copolymerization of acrylamide and N, N'-methylenebisacrylamide was performed in the presence of an amphiphilic Dex-g-PLA stabilizer. Polyacrylamide hydrogel nanoparticles were prepared in that way. PMID:18271550

  2. Crystalline imide/arylene ether copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J. (Inventor); Hergenrother, Paul M. (Inventor); Bass, Robert G. (Inventor)

    1995-01-01

    Crystalline imide/arylene ether block copolymers are prepared by reacting anhydride terminated poly(amic acids) with amine terminated poly)arylene ethers) in polar aprotic solvents and chemically or thermally cyclodehydrating the resulting intermediate poly(amic acids). The block copolymers of the invention have one glass transition temperature or two, depending on the particular structure and/or the compatibility of the block units. Most of these crystalline block copolymers for tough, solvent resistant films with high tensile properties. While all of the copolymers produced by the present invention are crystalline, testing reveals that copolymers with longer imide blocks or higher imide content have increased crystallinity.

  3. A self-consistent field study of diblock copolymer/charged particle system morphologies for nanofiltration membranes

    SciTech Connect

    Zhang, Bo; Ye, Xianggui; Edwards, Brian J.

    2013-12-28

    A combination of self-consistent field theory and density functional theory was used to examine the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Both neutral and interacting particles were examined, with and without favorable/unfavorable energetic potentials between the particles and the block segments. The phase diagrams of the various systems were constructed, allowing the identification of three types of ordered mesophases composed of lamellae, hexagonally packed cylinders, and spheroids. In particular, we examined the conditions under which the mesophases could be generated wherein the tethered particles were primarily located within the interface between the two blocks of the copolymer. Key factors influencing these properties were determined to be the particle position along the diblock chain, the interaction potentials of the blocks and particles, the block copolymer composition, and molecular weight of the copolymer.

  4. A self-consistent field study of diblock copolymer/charged particle system morphologies for nanofiltration membranes

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Ye, Xianggui; Edwards, Brian J.

    2013-12-01

    A combination of self-consistent field theory and density functional theory was used to examine the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Both neutral and interacting particles were examined, with and without favorable/unfavorable energetic potentials between the particles and the block segments. The phase diagrams of the various systems were constructed, allowing the identification of three types of ordered mesophases composed of lamellae, hexagonally packed cylinders, and spheroids. In particular, we examined the conditions under which the mesophases could be generated wherein the tethered particles were primarily located within the interface between the two blocks of the copolymer. Key factors influencing these properties were determined to be the particle position along the diblock chain, the interaction potentials of the blocks and particles, the block copolymer composition, and molecular weight of the copolymer.

  5. Polyether-polyester graft copolymer

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L. (Inventor)

    1987-01-01

    Described is a polyether graft polymer having improved solvent resistance and crystalline thermally reversible crosslinks. The copolymer is prepared by a novel process of anionic copolymerization. These polymers exhibit good solvent resistance and are well suited for aircraft parts. Previous aromatic polyethers, also known as polyphenylene oxides, have certain deficiencies which detract from their usefulness. These commercial polymers are often soluble in common solvents including the halocarbon and aromatic hydrocarbon types of paint thinners and removers. This limitation prevents the use of these polyethers in structural articles requiring frequent painting. In addition, the most popular commercially available polyether is a very high melting plastic. This makes it considerably more difficult to fabricate finished parts from this material. These problems are solved by providing an aromatic polyether graft copolymer with improved solvent resistance and crystalline thermally reversible crosslinks. The graft copolymer is formed by converting the carboxyl groups of a carboxylated polyphenylene oxide polymer to ionic carbonyl groups in a suitable solvent, reacting pivalolactone with the dissolved polymer, and adding acid to the solution to produce the graft copolymer.

  6. In vivo nanotoxicology of hybrid systems based on copolymer/silica/anticancer drug

    NASA Astrophysics Data System (ADS)

    Silveira, C. P.; Paula, A. J.; Apolinário, L. M.; Fávaro, W. J.; Durán, N.

    2015-05-01

    One of the major problems in cancer therapies is the high occurrence of side effects intrinsic of anticancer drugs. Doxorrubicin is a conventional anticancer molecule used to treat a wide range of cancer, such as breast, ovarian and prostate. However, its use is associated with a number of side effects like multidrug resistance and cardiotoxicity. The association with nanomaterials has been considered in the past decade to overcome the high toxicity of these drugs. In this context, mesoporous silica nanoparticles are great candidates to be used as carriers once they are very biocompatible. Taking into account the combination of nanoparticles and doxorrubicin, we treated rats with chemically induced prostate cancer with systems based on mesoporous silica nanoparticles and a thermoreversible block copolymer (Pluronic F-127) containing doxorrubicin. Preliminary results show a possible improvement in tumor conditions proportional to the concentration of the nanoparticles, opening a perspective to use mesoporous silica nanoparticles as carrier for doxorrubicin in prostate cancer treatment.

  7. Apoptosis induced by paclitaxel-loaded copolymer PLA–TPGS in Hep-G2 cells

    NASA Astrophysics Data System (ADS)

    Nguyen, Hoai Nam; Tran Thi, Hong Ha; Le Quang, Duong; Nguyen Thi, Toan; Tran Thi, Nhu Hang; Huong Le, Mai; Thu Ha, Phuong

    2012-12-01

    Paclitaxel is an important anticancer drug in clinical use for treatment of a variety of cancers. The clinical application of paclitaxel in cancer treatment is considerably limited due to its serious poor delivery characteristics. In this study paclitaxel-loaded copolymer poly(lactide)–d-α-tocopheryl polyethylene glycol 1000 succinate (PLA–TPGS) nanoparticles were prepared by a modified solvent extraction/evaporation technique. The characteristics of the nanoparticles, such as surface morphology, size distribution, zeta potential, solubility and apoptosis were investigated in vitro. The obtained spherical nanoparticles were negatively charged with a zeta potential of about ‑18 mV with the size around 44 nm and a narrow size distribution. The ability of paclitaxel-loaded PLA–TPGS nanoparticles to induce apoptosis in human hepatocellular carcinoma cell line (Hep-G2) indicates the possibility of developing paclitaxel nanoparticles as a potential universal cancer chemotherapeutic agent.

  8. Behavior of temperature-responsive copolymer microgels at the oil/water interface.

    PubMed

    Wu, Yaodong; Wiese, Susanne; Balaceanu, Andreea; Richtering, Walter; Pich, Andrij

    2014-07-01

    Herein, we investigate the interfacial behavior of temperature-sensitive aqueous microgels on the toluene/water interface. Copolymer microgels based on N-vinylcaprolactam (VCL) and two acrylamides, N-isopropylacrylamide (NIPAm) and N-isopropylmethacrylamide (NIPMAm), with various copolymer compositions were used in this study. It is revealed that these copolymer microgels have the similar internal structure, regardless of the chemical composition. A classic kinetics of interfacial tension with three distinct regimes is found in the dynamic interfacial tension plots of copolymer microgels, which is similar to inorganic nanoparticles and proteins. The influences of the copolymer composition and the temperature on the interfacial behavior of microgels are investigated. The results show that the interfacial behavior of copolymer microgels at the toluene/water interface follows exactly the trend of the volume phase behavior of microgels but, on the other hand, strongly depends upon the chemical compositions of copolymer microgels. In contrast, with respect to the size range of microgels studied here (50-500 nm), the size of the microgel has no influence on the interfacial tension. Below the volume phase transition temperature (VPTT), the equilibrium interfacial tensions of all microgel systems decrease as the temperature increases. Above VPTT, the equilibrium interfacial tension remains at a certain level for poly(N-vinylcaprolactam) (PVCL)- and poly(N-isopropylmethacrylamide) (PNIPMAm)-rich microgel systems and increases slightly for poly(N-isopropylacrylamide) (PNIPAm)-rich microgel systems. The evolution of dynamic interfacial tension for microgel solutions against toluene at T < VPTT is faster than that at T > VPTT, because of the reduced deformability of the microgel with the increase of the temperature. The softer microgels with lower cross-linking degrees exhibit faster kinetics of reduction of interfacial tension compared to those with more cross-linked degrees

  9. Direct Immersion Solvent Annealing of Nano-filled Block Copolymer Films

    NASA Astrophysics Data System (ADS)

    Longanecker, Melanie; Modi, Arvind; Yuan, Guangcui; Satija, Sushil; Bang, Joona; Karim, Alamgir; University of Akron Team; National Institute of Technology Collaboration; Korea University Collaboration

    The addition of nanoparticles to polymer films is a strategic approach to enhance film properties such as optical, thermal, hardness, conductivity, permeability etc. with inorganic components while maintaining an easily processable polymer matrix. To this end, the ``annealing'' of block copolymers while immersed directly in a chamber of solvent is examined to determine its efficacy in ordering nano-filled block copolymer films. Previously we have shown that it is possible to order neat block copolymer films in a mixture of solvents, and this research follows up that work. Specifically, we observe and utilize the effects of direct immersion solvent annealing (DIA) on lamellar poly(styrene-b-methyl methacrylate) thin films with loadings of gold nanoparticles as high as 25 percent by mass. Neutron reflection confirms that DIA is a viable technique applicable to ordering these highly loaded, nano-filled block copolymer systems. Some notable differences exist with respect to results on conservation of domain spacing that may be beneficial to film barrier properties, accomplished with minimal disruption of order and fast kinetics that is compatible with roll-to-roll techniques.

  10. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    .../acrylic copolymers shall not be used as polymer modifiers in vinyl chloride homo- or copolymers. (e... (other than articles composed of vinyl chloride homo- or copolymers) intended for use in contact with...

  11. Amphiphilic Copolymers of Polyfluorene Methacrylates Exhibiting Tunable Emissions for Ink-Jet Printing.

    PubMed

    Deng, Chao; Ling, Jun

    2016-08-01

    Functionalized polyfluorene receives more and more attention due to its wide applications. Here, the syntheses of three novel polyfluorene-based methacrylate macromonomers exhibiting a vast flexibility for further applications are reported. Their emissions strongly depend on the end groups and thus the macromonomers provide blue, green, and red emissions simultaneously with the same excitation light of 365 nm. Their well-defined copolymers with 2-(dimethylamino) ethyl methacrylate via reversible addition-fragmentation chain transfer polymerization are investigated in detail. These copolymers exhibit high quantum yields in solid film (up to 0.8), and self-assemble into photoluminescent nanoparticles in aqueous solutions with pure blue, green, and red emissions. By simply mixing them, perfect white light emission with high quality is obtained. These aqueous nanoparticles solutions are ready for ink-jet printing to produce exquisite bright and colorful fluorescent pictures. PMID:27310485

  12. Crystalline Imide/Arylene Ether Copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Hergenrother, Paul M.; Bass, Robert G.

    1991-01-01

    Series of imide/arylene ether block copolymers prepared by using arylene ether blocks to impart low melt viscosity, and imide blocks to provide high strength and other desirable mechanical properties. Work represents extension of LAR-14159 on imide/arylene ether copolymers in form of films, moldings, adhesives, and composite matrices. Copolymers potentially useful in variety of high-temperature aerospace and microelectronic applications.

  13. Protein-based nanoparticles for hydrophilic coating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cyanoacrylate nanoparticles have been studied in great detail over the past three decades. Conventionally, the mechanism of polymerization is anionic where the initiating species is the hydroxyl anion that was derived from dissociation of water. In the current research, amphiphilic copolymers were s...

  14. Barite formation in the presence of a commercial copolymer

    NASA Astrophysics Data System (ADS)

    Ruiz-Agudo, Cristina; Putnis, Christine; Ruiz-Agudo, Encarnacion; Putnis, Andrew

    2015-04-01

    early stages of barite precipitation in the presence and absence of this copolymer. With this purpose, barite was precipitated by mixing of BaCl2 and Na2SO4 solutions (with copolymer previously added to the sulphate solution). The process was quenched with ethanol at different times and the particles obtained were observed ex-situ using TEM. According to our observations, the organic molecule seems to be incorporated into barite nanoparticles, hindering or delaying their recrystallization into micron-sized crystals and stabilizing barite mesocrystals. Benton,W.J.; Collins, I.R.; Grimsey, I.M.; Parkinson, G.M.; Rodger, S.A. Faraday Discussions 1993, 95, 281-297. L. Qi; H. Cölfen; M. Antonietti. Angew. Chem. Int. Ed. 2000, 39 (3), 604-607. Wang, T.; Coelfen, H. Langmuir 2006, 22, 8975-8985. Mavredaki, E.; Neville, A.; Sorbie, K. S. Cryst. Growth Des. 2011, 11, 4751-4758. Acknowledgement: C.R-A. acknowledges a Marie Curie Fellowship: EU ITN MINSC (Mineral Scale Formation, PITN-GA-2011-290040).

  15. Segmented polyether-ester copolymers

    SciTech Connect

    Souffie, R.D.

    1982-08-01

    This article touches on the chemistry of manufacture and structure of thermoplastic elastomers. The physical properties and environmental resistance characteristics of these copolymers are related to their molecular makeup. Results indicate that segmented polyether esters, because of their basic chemical structure, are resistant to a wide range of oils, solvents and chemicals. They are also highly elastic, resilient polymers which can be both cost and performance effective when used in a number of industrial applications.

  16. Copolymers of fluorinated polydienes and sulfonated polystyrene

    DOEpatents

    Mays, Jimmy W.; Gido, Samuel P.; Huang, Tianzi; Hong, Kunlun

    2009-11-17

    Copolymers of fluorinated polydienes and sulfonated polystyrene and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization.

  17. Phase Behavior of Symmetric Sulfonated Block Copolymers

    SciTech Connect

    Park, Moon Jeong; Balsara, Nitash P.

    2008-08-21

    Phase behavior of poly(styrenesulfonate-methylbutylene) (PSS-PMB) block copolymers was studied by varying molecular weight, sulfonation level, and temperature. Molecular weights of the copolymers range from 2.9 to 117 kg/mol. Ordered lamellar, gyroid, hexagonally perforated lamellae, and hexagonally packed cylinder phases were observed in spite of the fact that the copolymers are nearly symmetric with PSS volume fractions between 0.45 and 0.50. The wide variety of morphologies seen in our copolymers is inconsistent with current theories on block copolymer phase behavior such as self-consistent field theory. Low molecular weight PSS-PMB copolymers (<6.2 kg/mol) show order-order and order-disorder phase transitions as a function of temperature. In contrast, the phase behavior of high molecular weight PSS-PMB copolymers (>7.7 kg/mol) is independent of temperature. Due to the large value of Flory-Huggins interaction parameter, x, between the sulfonated and non-sulfonated blocks, PSS-PMB copolymers with PSS and PMB molecular weights of 1.8 and 1.4 kg/mol, respectively, show the presence of an ordered gyroid phase with a 2.5 nm diameter PSS network. A variety of methods are used to estimate x between PSS and PMB chains as a function of sulfonation level. Some aspects of the observed phase behavior of PSS-PMB copolymers can be rationalized using x.

  18. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) The acrylate ester copolymer is a fully polymerized copolymer of ethyl acrylate, methyl methacrylate... emulsion defoamer. Disodium hydrogen phosphate Do. Formaldehyde Glyceryl monostearate Methyl...

  19. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) The acrylate ester copolymer is a fully polymerized copolymer of ethyl acrylate, methyl methacrylate... emulsion defoamer. Disodium hydrogen phosphate Do. Formaldehyde Glyceryl monostearate Methyl...

  20. Interfaces between Block Copolymer Domains

    NASA Astrophysics Data System (ADS)

    Kim, Jaeup; Jeong, Seong-Jun; Kim, Sang Ouk

    2011-03-01

    Block copolymers naturally form nanometer scale structures which repeat their geometry on a larger scale. Such a small scale periodic pattern can be used for various applications such as storage media, nano-circuits and optical filters. However, perfect alignment of block copolymer domains in the macroscopic scale is still a distant dream. The nanostructure formation usually occurs with spontaneously broken symmetry; hence it is easily infected by topological defects which sneak in due to entropic fluctuation and incomplete annealing. Careful annealing can gradually reduce the number of defects, but once kinetically trapped, it is extremely difficult to remove all the defects. One of the main reasons is that the defect finds a locally metastable morphology whose potential depth is large enough to prohibit further morphology evolution. In this work, the domain boundaries between differently oriented lamellar structures in thin film are studied. For the first time, it became possible to quantitatively study the block copolymer morphology in the transitional region, and it was shown that the twisted grain boundary is energetically favorable compared to the T-junction grain boundary. [Nano Letters, 9, 2300 (2010)]. This theoretical method successfully explained the experimental results.

  1. Homo- and co-polymerization of polysytrene-block-poly(acrylic acid)-coated metal nanoparticles.

    PubMed

    Wang, Hong; Song, Xiaohui; Liu, Cuicui; He, Jiating; Chong, Wen Han; Chen, Hongyu

    2014-08-26

    Amphiphilic block copolymers such as polystyrene-block-poly(acrylic acid) (PSPAA) give micelles that are known to undergo sphere-to-cylinder shape transformation. Exploiting this polymer property, core-shell nanoparticles coated in PSPAA can be "polymerized" into long chains following the chain-growth polymerization mode. This method is now extended to include a variety of different nanoparticles. A case study on the assembly process was carried out to understand the influence of the PAA block length, the surface ligand, and the size and morphology of the monomer nanoparticles. Shortening the PAA block promotes the reorganization of the amphiphilic copolymer in the micelles, which is essential for assembling large Au nanoparticles. Small Au nanoparticles can be directly "copolymerized" with empty PSPAA micelles into chains. The reaction time, acid quantity, and the [Au nanoparticles]/[PSPAA micelles] concentration ratio played important roles in controlling the sphere-cylinder-vesicle conversion of the PSPAA micelles, giving rise to different kinds of random "copolymers". With this knowledge, a general method is then developed to synthesize homo, random, and block "copolymers", where the basic units include small Au nanoparticles (d = 16 nm), large Au nanoparticles (d = 32 nm), Au nanorods, Te nanowires, and carbon nanotubes. Given the lack of means for assembling nanoparticles, advancing synthetic capabilities is of crucial importance. Our work provides convenient routes for combining nanoparticles into long-chain structures, facilitating rational design of complex nanostructures in the future. PMID:25000121

  2. Magnetic properties of barium ferrite dispersed within polystyrene-butadiene-styrene block copolymers.

    PubMed

    Chipara, M; Skomski, R; Ali, N; Hui, D; Sellmyer, D J

    2009-06-01

    Magnetic properties of nanocomposite materials obtained by dispersing barium ferrite nanoparticles within polystyrene-butadiene-styrene block copolymer, in the temperature range, 300 to 500 K are reported. The temperature dependence of the magnetization at saturation, averaged uniaxial magnetocrystalline anisotropy, and coercive field of thick films are analyzed. A "matrix effect" was noticed within the glass transition range of the hard component (polystyrene) of the polymeric matrix. The reported modifications of the magnetic properties were assigned to the competition between the magnetic and mechanical reorientation of nanoparticles within the polymeric matrix. Such modifications were not observed in barium ferrite dispersed in cement. PMID:19504902

  3. Transiently Responsive Block Copolymer Micelles Based on N-(2-Hydroxypropyl)methacrylamide Engineered with Hydrolyzable Ethylcarbonate Side Chains.

    PubMed

    Kasmi, Sabah; Louage, Benoit; Nuhn, Lutz; Van Driessche, Alexandra; Van Deun, Jan; Karalic, Izet; Risseeuw, Martijn; Van Calenbergh, Serge; Hoogenboom, Richard; De Rycke, Riet; De Wever, Olivier; Hennink, Wim E; De Geest, Bruno G

    2016-01-11

    The lack of selectivity and low solubility of many chemotherapeutics impels the development of different biocompatible nanosized drug carriers. Amphiphilic block copolymers, composed of a hydrophilic and hydrophobic domain, show great potential because of their small size, large solubilizing power and loading capacity. In this paper, we introduce a new class of degradable temperature-responsive block copolymers based on the modification of N-(2-hydroxypropyl)methacrylamide (HPMA) with an ethyl group via a hydrolytically sensitive carbonate ester, polymerized by radical polymerization using a PEG-based macroinitiatior. The micellization and temperature-responsive behavior of the PEG-poly(HPMA-EC) block copolymer were investigated by dynamic light scattering (DLS). We observed that the polymer exhibits lower critical solution temperature (LCST) behavior and that above the cloud point (cp) of 17 °C the block copolymer self-assembles in micelles with a diameter of 40 nm. Flow cytometry analysis and confocal microscopy show a dose-dependent cellular uptake of the micelles loaded with a hydrophobic dye. The block copolymer nanoparticles were capable of delivering the hydrophobic payload into cancer cells in both 2D and 3D in vitro cultures. The block copolymer has excellent cytocompatibility, whereas loading the particles with the hydrophobic anticancer drug paclitaxel results in a dose-dependent decrease in cell viability. PMID:26650350

  4. Thermosensitive AB4 four-armed star PNIPAM-b-HTPB multiblock copolymer micelles for camptothecin drug release.

    PubMed

    Luo, Yan-Ling; Fu, Jing-Yu; Xu, Feng; Chen, Ya-Shao; Zhang, Bin

    2014-01-01

    Thermo-sensitive poly(N-isoproplacrylamide)m-block-hydroxyl-terminated polybutadiene-block-poly(N-isoproplacrylamide)m (PNIPAMm-b-HTPB-b-PNIPAMm, m = 1 or 2) block copolymers, AB4 four-armed star multiblock and linear triblock copolymers, were synthesized by ATRP with HTPB as central blocks, and characterization was performed by (1)H NMR, Fourier transform infrared, and size exclusion chromatography. The multiblock copolymers could spontaneously assemble into more regular spherical core-shell nanoscale micelles than the linear triblock copolymer. The physicochemical properties were detected by a surface tension, nanoparticle analyzer, transmission electron microscope (TEM), dynamic light scattering, and UV-vis measurements. The multiblock copolymer micelles had lower critical micelle concentration than the linear counterpart, TEM size from 100 to 120 nm, and the hydrodynamic diameters below 150 nm. The micelles exhibited thermo-dependent size change, with low critical solution temperature of about 33-35 °C. The characteristic parameters were affected by the composition ratios, length of PNIPAM blocks, and molecular architectures. The camptothecin release demonstrated that the drug release was thermo-responsive, accompanied by the temperature-induced structural changes of the micelles. MTT assays were performed to evaluate the biocompatibility or cytotoxicity of the prepared copolymer micelles. PMID:24236748

  5. Synthesis and in vivo magnetic resonance imaging evaluation of biocompatible branched copolymer nanocontrast agents.

    PubMed

    Jackson, Alexander W; Chandrasekharan, Prashant; Shi, Jian; Rannard, Steven P; Liu, Quan; Yang, Chang-Tong; He, Tao

    2015-01-01

    Branched copolymer nanoparticles (D(h) =20-35 nm) possessing 1,4,7, 10-tetraazacyclododecane-N,N',N″,N‴-tetraacetic acid macrocycles within their cores have been synthesized and applied as magnetic resonance imaging (MRI) nanosized contrast agents in vivo. These nanoparticles have been generated from novel functional monomers via reversible addition-fragmentation chain transfer polymerization. The process is very robust and synthetically straightforward. Chelation with gadolinium and preliminary in vivo experiments have demonstrated promising characteristics as MRI contrast agents with prolonged blood retention time, good biocompatibility, and an intravascular distribution. The ability of these nanoparticles to perfuse and passively target tumor cells through the enhanced permeability and retention effect is also demonstrated. These novel highly functional nanoparticle platforms have succinimidyl ester-activated benzoate functionalities within their corona, which make them suitable for future peptide conjugation and subsequent active cell-targeted MRI or the conjugation of fluorophores for bimodal imaging. We have also demonstrated that these branched copolymer nanoparticles are able to noncovalently encapsulate hydrophobic guest molecules, which could allow simultaneous bioimaging and drug delivery. PMID:26425088

  6. Synthesis and in vivo magnetic resonance imaging evaluation of biocompatible branched copolymer nanocontrast agents

    PubMed Central

    Jackson, Alexander W; Chandrasekharan, Prashant; Shi, Jian; Rannard, Steven P; Liu, Quan; Yang, Chang-Tong; He, Tao

    2015-01-01

    Branched copolymer nanoparticles (Dh =20–35 nm) possessing 1,4,7, 10-tetraazacyclododecane-N,N′,N″,N‴-tetraacetic acid macrocycles within their cores have been synthesized and applied as magnetic resonance imaging (MRI) nanosized contrast agents in vivo. These nanoparticles have been generated from novel functional monomers via reversible addition–fragmentation chain transfer polymerization. The process is very robust and synthetically straightforward. Chelation with gadolinium and preliminary in vivo experiments have demonstrated promising characteristics as MRI contrast agents with prolonged blood retention time, good biocompatibility, and an intravascular distribution. The ability of these nanoparticles to perfuse and passively target tumor cells through the enhanced permeability and retention effect is also demonstrated. These novel highly functional nanoparticle platforms have succinimidyl ester-activated benzoate functionalities within their corona, which make them suitable for future peptide conjugation and subsequent active cell-targeted MRI or the conjugation of fluorophores for bimodal imaging. We have also demonstrated that these branched copolymer nanoparticles are able to noncovalently encapsulate hydrophobic guest molecules, which could allow simultaneous bioimaging and drug delivery. PMID:26425088

  7. Stable, polymer-directed and SPION-nucleated magnetic amphiphilic block copolymer nanoprecipitates with readily reversible assembly in magnetic fields.

    PubMed

    Giardiello, Marco; Hatton, Fiona L; Slater, Rebecca A; Chambon, Pierre; North, Jocelyn; Peacock, Anita K; He, Tao; McDonald, Tom O; Owen, Andrew; Rannard, Steve P

    2016-03-24

    The formation of inorganic-organic magnetic nanocomposites using reactive chemistry often leads to a loss of super-paramagnetisim when conducted in the presence of iron oxide nanoparticles. We present here a low energy and chemically-mild process of co-nanoprecipitation using SPIONs and homopolymers or amphiphilic block copolymers, of varying architecture and hydrophilic/hydrophobic balance, which efficiently generates near monodisperse SPION-containing polymer nanoparticles with complete retention of magnetism, and highly reversible aggregation and redispersion behaviour. When linear and branched block copolymers with inherent water-solubility are used, a SPION-directed nanoprecipitation mechanism appears to dominate the nanoparticle formation presenting new opportunities for tailoring and scaling highly functional systems for a range of applications. PMID:26973155

  8. Effect of chain topology of block copolymer on micellization: ring vs linear block copolymer

    NASA Astrophysics Data System (ADS)

    Kim, Kwang Hee; Huh, June; Jo, Won Ho

    2003-03-01

    The aggregation of amphiphilic block copolymers in solution to form micelles has attracted great interest in recent years because of its importance in industrial applications. Many studies on these systems have mainly focused on a di- or triblock copolymer and much less attention was given to other architectures such as ring block copolymer. Recent experimental work has extended those works to include ring block copolymer, made by end-linking the triblock copolymer. Although the micellization of the ring block copolymer seemed to be favored over that of the linear triblock copolymer, two block copolymers showed similar values of cmc in experiments. In the present work, micellization of ring block copolymer (ring-B9A8) was simulated by Brownian dyanmics and micellar behavior is compared with triblock copolymer (A4B9A4) to investigate more systematically the effect of molecular architecture. Critical micelle concentration (cmc), average aggregation number and micellar distribution are compared with corresponding quantities measured for linear triblock copolymers having the same chain length and composition. Simulation results show that the cmc of ring-B9A8 is smaller than that of A4B9A4. The difference is explained by simple mean-field type theory.

  9. Stable, polymer-directed and SPION-nucleated magnetic amphiphilic block copolymer nanoprecipitates with readily reversible assembly in magnetic fields

    NASA Astrophysics Data System (ADS)

    Giardiello, Marco; Hatton, Fiona L.; Slater, Rebecca A.; Chambon, Pierre; North, Jocelyn; Peacock, Anita K.; He, Tao; McDonald, Tom O.; Owen, Andrew; Rannard, Steve P.

    2016-03-01

    The formation of inorganic-organic magnetic nanocomposites using reactive chemistry often leads to a loss of super-paramagnetisim when conducted in the presence of iron oxide nanoparticles. We present here a low energy and chemically-mild process of co-nanoprecipitation using SPIONs and homopolymers or amphiphilic block copolymers, of varying architecture and hydrophilic/hydrophobic balance, which efficiently generates near monodisperse SPION-containing polymer nanoparticles with complete retention of magnetism, and highly reversible aggregation and redispersion behaviour. When linear and branched block copolymers with inherent water-solubility are used, a SPION-directed nanoprecipitation mechanism appears to dominate the nanoparticle formation presenting new opportunities for tailoring and scaling highly functional systems for a range of applications.The formation of inorganic-organic magnetic nanocomposites using reactive chemistry often leads to a loss of super-paramagnetisim when conducted in the presence of iron oxide nanoparticles. We present here a low energy and chemically-mild process of co-nanoprecipitation using SPIONs and homopolymers or amphiphilic block copolymers, of varying architecture and hydrophilic/hydrophobic balance, which efficiently generates near monodisperse SPION-containing polymer nanoparticles with complete retention of magnetism, and highly reversible aggregation and redispersion behaviour. When linear and branched block copolymers with inherent water-solubility are used, a SPION-directed nanoprecipitation mechanism appears to dominate the nanoparticle formation presenting new opportunities for tailoring and scaling highly functional systems for a range of applications. Electronic supplementary information (ESI) available: Additional experimental details, NMR spectra, GPC chromatograms, kinetics experiments, graphs of nanopreciptate aggregation and cycling studies and SPION characterisation. See DOI: 10.1039/c6nr00788k

  10. 21 CFR 180.22 - Acrylonitrile copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... ADDITIVES PERMITTED IN FOOD OR IN CONTACT WITH FOOD ON AN INTERIM BASIS PENDING ADDITIONAL STUDY Specific Requirements for Certain Food Additives § 180.22 Acrylonitrile copolymers. Acrylonitrile copolymers may be... uses subject to the denial are thereafter unapproved food additives and consequently unlawful. (3)...

  11. Dimensionally Stable Ether-Containing Polyimide Copolymers

    NASA Technical Reports Server (NTRS)

    Fay, Catharine C. (Inventor); St.Clair, Anne K. (Inventor)

    1999-01-01

    Novel polyimide copolymers containing ether linkages were prepared by the reaction of an equimolar amount of dianhydride and a combination of diamines. The polyimide copolymers described herein possess the unique features of low moisture uptake, dimensional stability, good mechanical properties, and moderate glass transition temperatures. These materials have potential application as encapsulants and interlayer dielectrics.

  12. Imide/arylene ether block copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, B. J.; Hergenrother, P. M.; Bass, R. G.

    1991-01-01

    Two series of imide/arylene either block copolymers were prepared using an arylene ether block and either an amorphous or semi-crystalline imide block. The resulting copolymers were characterized and selected physical and mechanical properties were determined. These results, as well as comparisons to the homopolymer properties, are discussed.

  13. Thermochemical characteristics of chitosan-polylactide copolymers

    NASA Astrophysics Data System (ADS)

    Goruynova, P. E.; Larina, V. N.; Smirnova, N. N.; Tsverova, N. E.; Smirnova, L. A.

    2016-05-01

    The energies of combustion of chitosan and its block-copolymers with different polylactide contents are determined in a static bomb calorimeter. Standard enthalpies of combustion and formation are calculated for these substances. The dependences of the thermochemical characteristics on block-copolymer composition are determined and discussed.

  14. 21 CFR 173.65 - Divinylbenzene copolymer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Adjuvants for Food Treatment § 173.65 Divinylbenzene copolymer. Divinylbenzene copolymer may be used for the... extraction with a water soluble alcohol until the level of divinylbenzene in the extract is less than 50... is then treated with water according to the manufacturer's recommendation to remove the...

  15. Nanoparticle-Reinforced Associative Network Hydrogels

    PubMed Central

    Agrawal, Sarvesh K.; Sanabria-DeLong, Naomi; Tew, Gregory N.; Bhatia, Surita R.

    2009-01-01

    ABA triblock copolymers in solvents selective for the midblock are known to form associative micellar gels. We have modified the structure and rheology of ABA triblock copolymer gels comprising poly(lactide)-poly(ethylene oxide)-poly(lactide) (PLA-PEO-PLA) through addition of a clay nanoparticle, laponite. Addition of laponite particles resulted in additional junction points in the gel via adsorption of the PEO corona chains onto the clay surfaces. Rheological measurements showed that this strategy led to a significant enhancement of the gel elastic modulus with small amounts of nanoparticles. Further characterization using SAXS and DLS confirmed that nanoparticles increase the intermicellar attraction and result in aggregation of PLA-PEO-PLA micelles. PMID:18947244

  16. Processible Polyaniline Copolymers and Complexes.

    NASA Astrophysics Data System (ADS)

    Liao, Yun-Hsin

    1995-01-01

    Polyaniline (PANI) is an intractable polymer due to the difficulty of melt processing or dissolving it in common solvents. The purpose of the present investigation was to prepare a new class of conducting polyanilines with better solubility both in base and dope forms by (1) adding external salt to break aggregated chains, (2) introducing ring substituted units onto the backbone without disturbing the coplanar structure, and (3) complexing with polymeric dopants to form a soluble polymer complex. Aggregation of PANI chains in dilute solution was investigated in N-methyl-2-pyrrolidinone (NMP) by light scattering, gel permeation chromatography, and viscosity measurements. The aggregation of chains resulted in a negative second virial coefficient in light scattering measurement, a bimodal molecular weight distribution in gel permeation chromatography, and concave reduced viscosity curves. The aggregates can be broken by adding external salt, which resulting in a higher reduced viscosity. The driving force for aggregation is assumed to be a combination of hydrogen bonding between the imine and amine groups, and the rigidity of backbone. The aggregation was modeled to occur via side-on packing of PANI chains. The ring substituted PANI copolymers, poly(aniline -co-phenetidine) were synthesized by chemical oxidation copolymerization using ammonium persulfate as an oxidant. The degree of copolymerization declined with an increasing feed of o-phenetidine in the reaction mixture. The o-phenetidine had a higher reactivity than aniline in copolymerization resulting in a higher content of o-phenetidine in copolymers. The resulting copolymers can be readily dissolved in NMP up to 20% (w/w), and other common solvents, and solutions possess a longer gelation time. The highly soluble copolymer with 20 mole % o-phenetidine in the backbone has same order of conductivity as the unsubstituted PANI after it is doped by HCl. Complexation of PANI and polymeric dopant, poly

  17. Pattern transfer using block copolymers.

    PubMed

    Gu, Xiaodan; Gunkel, Ilja; Russell, Thomas P

    2013-10-13

    To meet the increasing demand for patterning smaller feature sizes, a lithography technique is required with the ability to pattern sub-20 nm features. While top-down photolithography is approaching its limit in the continued drive to meet Moore's law, the use of directed self-assembly (DSA) of block copolymers (BCPs) offers a promising route to meet this challenge in achieving nanometre feature sizes. Recent developments in BCP lithography and in the DSA of BCPs are reviewed. While tremendous advances have been made in this field, there are still hurdles that need to be overcome to realize the full potential of BCPs and their actual use. PMID:24000358

  18. Combinatorial Block Copolymer Ordering on Tunable Rough

    SciTech Connect

    Kulkarni M. M.; Yager K.; Sharma, A.; Karim, A.

    2012-05-01

    Morphology control of block copolymer (BCP) thin films through substrate interaction via controlled roughness parameters is of significant interest for numerous high-tech applications ranging from solar cells to high-density storage media. While effects of substrate surface energy (SE) and roughness (R) on BCP morphology have been individually investigated, their synergistic effects have not been explored in any systematic manner. Interestingly, orientation response of BCP to changes in SE can be similar to what can be accomplished with variations in R. Here we present a novel approach for orienting lamellar BCP films of poly(styrene)-block-poly(methyl methacrylate) (PS-PMMA) on spin-coated xerogel (a dried gel of silica nanoparticle network) substrate with simultaneously tunable surface energy, {gamma}{sub s} {approx} 29-53 mJ/m{sup 2}, by UVO exposure and roughness, R{sub rms} {approx} 0.5-30 nm, by sol-gel processing steps of regulating the catalyst concentration and sol aging time. As in previous BCP orientation studies on 20 nm diameter monodisperse silica nanoparticle coated surface, we find a similar but broadened oscillatory BCP orientation behavior with film thickness due to the random rather than periodic rough surfaces. We also find that higher random roughness amplitude is not the necessary criteria for obtaining a vertical orientation of BCP lamellae. Rather, a high surface fractal dimension (D{sub f} > 2.4) of the rough substrate in conjunction with an optimal substrate surface energy {gamma}{sub s} 29 mJ/m{sup 2} results in 100% vertically oriented lamellar microdomains. The AFM measured film surface microstructure correlates well with the internal 3D BCP film structure probed by grazing incidence small-angle X-ray scattering (GISAXS) and rotational small-angle neutron scattering (SANS). In contrast to tunable self-assembled monolayer (SAM)-coated substrates, the xerogel films are very durable and retain their chemical properties over period of

  19. Rapid self-assembly of block copolymers to photonic crystals

    DOEpatents

    Xia, Yan; Sveinbjornsson, Benjamin R; Grubbs, Robert H; Weitekamp, Raymond; Miyake, Garret M; Atwater, Harry A; Piunova, Victoria; Daeffler, Christopher Scot; Hong, Sung Woo; Gu, Weiyin; Russell, Thomas P.

    2016-07-05

    The invention provides a class of copolymers having useful properties, including brush block copolymers, wedge-type block copolymers and hybrid wedge and polymer block copolymers. In an embodiment, for example, block copolymers of the invention incorporate chemically different blocks comprising polymer size chain groups and/or wedge groups that significantly inhibit chain entanglement, thereby enhancing molecular self-assembly processes for generating a range of supramolecular structures, such as periodic nanostructures and microstructures. The present invention also provides useful methods of making and using copolymers, including block copolymers.

  20. The Interaction of CORM-2 with Block Copolymers Containing Poly(4-vinylpyridine): Macromolecular Scaffolds for Carbon Monoxide Delivery in Biological Systems.

    PubMed

    Nguyen, Diep; Adnan, Nik Nik M; Oliver, Susan; Boyer, Cyrille

    2016-05-01

    CORM-2, tricarbonyldichlororuthenium(II) dimer (Ru2 Cl4 (CO)6 ), is a common carbon monoxide releasing molecule (CORM) studied both in vitro and in vivo, but this compound possesses poor water solubility and a short half-life, which hinders its clinical development. Herein, for the first time the conjugation of CORM-2 is reported with a copolymer containing poly(4-vinylpyridine) to yield water-soluble CO-releasing polymeric nanoparticles. CORM-2 is rapidly conjugated to copolymers through pyridine groups as confirmed by inductively coupled plasma-optical emission spectroscopy and infrared spectroscopy. In comparison with free CORM-2, the copolymers functionalized with CORM-2 display better water solubility and the CO release from the polymer-based CORM is slow and sustained. This study paves the way for the potential use of a copolymer encapsulating CORM-2 as a therapeutic agent. PMID:26945898

  1. Application of poly(ethylene glycol)-distearoylphosphatidylethanolamine (PEG-DSPE) block copolymers and their derivatives as nanomaterials in drug delivery.

    PubMed

    Wang, Rongrong; Xiao, Renzhong; Zeng, Zhaowu; Xu, Lili; Wang, Junjie

    2012-01-01

    Poly(ethylene glycol)-distearoylphosphatidylethanolamine (PEG-DSPE) block copolymers are biocompatible and amphiphilic polymers that can be widely utilized in the preparation of liposomes, polymeric nanoparticles, polymer hybrid nanoparticles, solid lipid nanoparticles, lipid-polymer hybrid nanoparticles, and microemulsions. Particularly, the terminal groups of PEG can be activated and linked to various targeting ligands, which can prolong the circulation time, improve the drug bioavailability, reduce undesirable side effects, and especially target specific cells, tissues, and even the intracellular localization in organelles. This review herein aims to describe recent developments in drug carriers exploiting PEG-DSPE block copolymers and their derivatives, and the incorporation of different ligands to the end groups of PEG-DSPE to target delivery, focusing on their modification approaches, advantages, applications, and the probable associated drawbacks. PMID:22904628

  2. Lateral structuring and stability phenomena induced by block copolymers and core-shell nanogel particles at immiscible polymer/polymer interfaces

    NASA Astrophysics Data System (ADS)

    Gozen, Arif Omer

    We have investigated the parameters such as copolymer/nanoparticle concentration, architecture and molecular weight combined with film thickness, time and temperature in order to develop a molecular-level insight on how lateral interfacial structuring occurs at immiscible polymer/polymer interfaces. I order to develop a molecular-level understanding of how these 'smart' self-assembling materials and core-shell nanogel particles interact both intra- and inter-molecularly and form ordered structures in bulk, as well as at immiscible interfaces, we first focused on the response of core-shell polymer nanoparticles, designated CSNGs, composed of a cross-linked divinylbenzene core and poly(methyl methacrylate) (PMMA) arms as they segregate from PMMA homopolymer. We have demonstrated that these nanogel particles exhibit autophobic character when dispersed in high molecular weight homopolymer matrices and segregate to the interface with another fluid. We have further explored the migration of these new-generation nanogel particles (CSNG-Rs) segregating from PS homopolymer to PS/PMMA interfaces. Unlike the instability patterns observed with the CSNGs, which exhibit classical nucleation and growth mechanism with circular hole formation, we have observed an intriguing dewetting pattern and CSNG-Rs forming lateral aggregates and tentacle-like structures at the interface. In parallel with our core-shell particle studies, we have also explored the structuring of copolymer molecules that are far from equilibrium in bulk and complex laminate of polymer thin films. Our early triblock copolymer studies have proven that molecular asymmetry has a profound effect on order-disorder transition temperature. We focused primarily on the effect of the copolymer chemical composition (i.e., block sizes) on the dewetting behavior of PS/SM thin films on PMMA. We elucidate the interfacial segregation and concurrent micellization of diblock copolymers in a dynamically evolving environment with

  3. Magnetic Hydrogels from Alkyne/Cobalt Carbonyl-Functionalized ABA Triblock Copolymers.

    PubMed

    Jiang, Bingyin; Hom, Wendy L; Chen, Xianyin; Yu, Pengqing; Pavelka, Laura C; Kisslinger, Kim; Parise, John B; Bhatia, Surita R; Grubbs, Robert B

    2016-04-01

    A series of alkyne-functionalized poly(4-(phenylethynyl)styrene)-block-poly(ethylene oxide)-block-poly(4-(phenylethynyl)styrene) (PPES-b-PEO-b-PPES) ABA triblock copolymers was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. PESn[Co2(CO)6]x-EO800-PESn[Co2(CO)6]x ABA triblock copolymer/cobalt adducts (10-67 wt % PEO) were subsequently prepared by reaction of the alkyne-functionalized PPES block with Co2(CO)8 and their phase behavior was studied by TEM. Heating triblock copolymer/cobalt carbonyl adducts at 120 °C led to cross-linking of the PPES/Co domains and the formation of magnetic cobalt nanoparticles within the PPES/Co domains. Magnetic hydrogels could be prepared by swelling the PEO domains of the cross-linked materials with water. Swelling tests, rheological studies and actuation tests demonstrated that the water capacity and modulus of the hydrogels were dependent upon the composition of the block copolymer precursors. PMID:26958699

  4. Degradation behavior and biosafety studies of the mPEG-PLGA-PLL copolymer.

    PubMed

    He, Zelai; Sun, Ying; Cao, Jun; Duan, Yourong

    2016-04-28

    In a previous study, a novel biodegradable multiblock copolymer, monomethoxy(poly-ethylene glycol)-poly(d,l-lactide-co-glycolide)-poly(l-lysine) (PEAL), was developed as a new drug carrier material. It is imperative to study the biocompatibility and degradation behavior of PEAL to pave the way for clinical applications. Here, we systematically demonstrated that the PEAL copolymer has the appropriate hydrophilicity and biosafety. The degradation rate of the PEAL films was obtained by observing changes in mass, molecular weight (Mw), Mw distribution and degradation products. The degradation rate was observed to have a highly positive correlation with the pH of the medium and negative correlation with the ratio of lactic acid to glycolic acid (LA/GA). Cytotoxicity tests indicated that the degradation products of the copolymer were non-toxic to cells. In zebrafish embryos, the PEAL nanoparticles had no obvious impact on heart rate, production of reactive oxygen species, mortality, or cell apoptosis, and they were observed to have a long circulation time. Therefore, the PEAL copolymer has great potential for use as a drug carrier material. PMID:27067001

  5. Instantaneous Directional Growth of Block Copolymer Nanowires During Heterogeneous Radical Polymerization (HRP).

    PubMed

    Lu, Chunliang; Urban, Marek W

    2016-04-13

    Polymeric nanowires that consist of ultrahigh molecular weight block copolymers were instantaneously prepared via one-step surfactant-free heterogeneous radical polymerization (HRP). Under heterogeneous reaction and initiator-starvation conditions, the sequential copolymerization of hydrophilic and hydrophobic monomers facilitates the formation of amphiphilic ultrahigh molecular weight block copolymers, which instantaneously assemble to polymeric nanowires. As polymerization progresses, initially formed nanoparticles exhibit the directional growth due to localized repulsive forces of hydrophilic blocks and confinement of the hydrophobic blocks that adopt favorable high aspect ratio nanowire morphologies. Using one-step synthetic approach that requires only four ingredients (water as a solvent, two polymerizable monomers (one hydrophilic and one hydrophobic), and water-soluble initiator), block copolymer nanowires ∼70 nm in diameter and hundreds of microns in length are instantaneously grown. For example, when 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) and styrene (St) were copolymerized, high aspect ratio nanowires consist of ultrahigh (>10(6) g/mol) molecular weight pDMAEMA-b-St block copolymers and the presence of temperature responsive pDMAEMA blocks facilitates nanowire diameter changes as a function of temperature. These morphologies may serve as structural components of the higher order biological constructs at micro and larger length scales, ranging from single strand nanowires to engineered biomolecular networks capable of responding to diverse and transient environmental signals, and capable of dimensional changes triggered by external stimuli. PMID:27002238

  6. Aqueous worm gels can be reconstituted from freeze-dried diblock copolymer powder.

    PubMed

    Kocik, M K; Mykhaylyk, O O; Armes, S P

    2014-06-14

    Worm-like diblock copolymer nanoparticles comprising poly(glycerol monomethacrylate) (PGMA) as a stabilizer block and poly(2-hydroxypropyl methacrylate) (PHPMA) as a core-forming block were readily synthesized at 10% w/w solids via aqueous dispersion polymerization at 70 °C using Reversible Addition-Fragmentation chain Transfer (RAFT) chemistry. On cooling to 20 °C, soft transparent free-standing gels are formed due to multiple inter-worm interactions. These aqueous PGMA-PHPMA diblock copolymer worms were freeze-dried, then redispersed in water with cooling to 3-5 °C before warming up to 20 °C; this protocol ensures molecular dissolution of the copolymer chains, which aids formation of a transparent aqueous gel. Rheology, SAXS and TEM studies confirm that such reconstituted gels comprise formed PGMA-PHPMA copolymer worms and they possess essentially the same physical properties determined for the original worm gels prior to freeze-drying. Such worm gel reconstitution is expected to be highly beneficial in the context of various biomedical applications, since it enables worm gels to be readily prepared using a wide range of cell growth media as the continuous aqueous phase. PMID:24733440

  7. Morphology and Dynamic Mechanical Properties of Styrene Containing Tri-Block Copolymers for Electromagnetic Wave Interaction Applications

    NASA Astrophysics Data System (ADS)

    Peddini, S.; Mauritz, K.; Nikles, D.; Weston, J.

    2008-03-01

    Styrene containing triblock copolymers, namely poly(styrene-ethylene/butylene-styrene) (SEBS) and poly(styrene-butadiene-styrene)] (SBS), were selectively modified by attaching polar groups to facilitate the in-growth of an inorganic component. In case of SEBS, the styrene block was sulfonated, and in SBS, the butadiene block was hydroxylated. The extent of modification was determined by analytical and spectroscopic methods. This presentation shows the morphology and dynamical mechanical properties of both block copolymers before and after modification. Nanocomposites of these block copolymers were prepared by inclusion of magnetic metal oxides via an in-situ precipitation and self assembly processes and their morphology and dynamical mechanical properties were studied. Magnetic properties of these polymers filled with iron oxide nanoparticles were measured using an alternating gradient magnetometer (AGM) at room temperature to observe the magnetic hysteresis.

  8. Preparation of superhydrophobic films based on the diblock copolymer P(TFEMA-r-Sty)-b-PCEMA.

    PubMed

    Zhang, Ganwei; Hu, Jiwen; Tu, Yuanyuan; He, Guping; Li, Fei; Zou, Hailiang; Lin, Shudong; Yang, Gonghua

    2015-07-15

    The diblock copolymer poly[2,2,2-trifluoroethyl methacrylate-r-styrene]-block-poly[(2-cinnamoyloxyethyl methacrylate)] [P(TFEMA-r-Sty)-b-PCEMA] was synthesized via atom transfer radical polymerization. The copolymer underwent self-assembly in TFEMA/CH2Cl2 to form spherical micelles. Photo-cross-linking of the PCEMA domains of these micelles yielded cross-linked nanoparticles. The cross-linked nanoparticles were subsequently cast from CH2Cl2/methanol solvent mixtures at methanol volume fractions of more than 30% to yield rough surfaces bearing small nanobumps on micron-sized aggregations that were connected together to form cross-linked nanoparticles. These surfaces were superhydrophobic with a water contact angle of 161 ± 1° and a sliding angle of 6 ± 1°. Spraying these nanoparticles onto substrates exhibiting microscale roughness, such as filter paper, by a traditional coating technique also created superhydrophobic surfaces. A thin layer of nanoscale spherical protrusions was observed on the microscale fibers of filter paper by scanning electron microscopy. The coated filter paper samples exhibited a water contact angle and a sliding angle of 153 ± 1° and 9 ± 1°, respectively. PMID:26145165

  9. Combination of magnetic and enhanced mechanical properties for copolymer-grafted magnetite composite thermoplastic elastomers.

    PubMed

    Jiang, Feng; Zhang, Yaqiong; Wang, Zhongkai; Wang, Wentao; Xu, Zhaohua; Wang, Zhigang

    2015-05-20

    Composite thermoplastic elastomers (CTPEs) of magnetic copolymer-grafted nanoparticles (magnetite, Fe3O4) were synthesized and characterized to generate magnetic CTPEs, which combined the magnetic property of Fe3O4 nanoparticles and the thermoplastic elasticity of the grafted amorphous polymer matrix. Fe3O4 nanoparticles served as stiff, multiple physical cross-linking points homogeneously dispersed in the grafted poly(n-butyl acrylate-co-methyl methacrylate) rubbery matrix synthesized via the activators regenerated by electron transfer for atom transfer radical polymerization method (ARGET ATRP). The preparation technique for magnetic CTPEs opened a new route toward developing a wide spectrum of magnetic elastomeric materials with strongly enhanced macroscopic properties. Differential scanning calorimetry (DSC) was used to measure the glass transition temperatures, and thermogravimetric analysis (TGA) was used to examine thermal stabilities of these CTPEs. The magnetic property could be conveniently tuned by adjusting the content of Fe3O4 nanoparticles in CTPEs. Compared to their linear copolymers, these magnetic CTPEs showed significant increases in tensile strength and elastic recovery. In situ small-angle X-ray scattering measurement was conducted to reveal the microstructural evolution of CTPEs during tensile deformation. PMID:25954980

  10. Block copolymers encapsulated poly (aryl benzyl ether) dendrimer silicon (IV) phthalocyanine for in vivo and in vitro photodynamic efficacy of choroidal neovascularization

    NASA Astrophysics Data System (ADS)

    Wang, Xiongwei; Chen, Kuizhi; Huang, Zheng; Peng, Yiru

    2015-03-01

    A novel series of poly (aryl benzyl ether) dendrimer silicon phthalocyanines loaded block copolymers ethoxypoly(ethylene glycol)-poly (lactic-co-glycolic acid) (MPEG-PLGA)were formed. The time-dependent intracellular uptake of nanoparticles in HUVECs cells increased as they were incorporated into nanoparticles. With its highly effective selective accumulation on choroidal neovascularization(CNV). This treatment resulted in a efficacious choroidal neovascularization (CNV) occlusion with minimal unfavorable phototoxicity.

  11. Injectible bodily prosthetics employing methacrylic copolymer gels

    DOEpatents

    Mallapragada, Surya K.; Anderson, Brian C.

    2007-02-27

    The present invention provides novel block copolymers as structural supplements for injectible bodily prosthetics employed in medical or cosmetic procedures. The invention also includes the use of such block copolymers as nucleus pulposus replacement materials for the treatment of degenerative disc disorders and spinal injuries. The copolymers are constructed by polymerization of a tertiary amine methacrylate with either a (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) polymer, such as the commercially available Pluronic.RTM. polymers, or a poly(ethylene glycol) methyl ether polymer.

  12. Block Copolymer Membranes for Biofuel Purification

    NASA Astrophysics Data System (ADS)

    Evren Ozcam, Ali; Balsara, Nitash

    2012-02-01

    Purification of biofuels such as ethanol is a matter of considerable concern as they are produced in complex multicomponent fermentation broths. Our objective is to design pervaporation membranes for concentrating ethanol from dilute aqueous mixtures. Polystyrene-b-polydimethylsiloxane-b-polystyrene block copolymers were synthesized by anionic polymerization. The polydimethylsiloxane domains provide ethanol-transporting pathways, while the polystyrene domains provide structural integrity for the membrane. The morphology of the membranes is governed by the composition of the block copolymer while the size of the domains is governed by the molecular weight of the block copolymer. Pervaporation data as a function of these two parameters will be presented.

  13. LaRC-ITPI/arylene ether copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Working, Dennis C.

    1991-01-01

    As part of an effort to develop high performance structural resins for aerospace applications, work has continued on block copolymers containing imide and arylene ether segments. The arylene ether block used in this study contains a bulky fluorene group in the polymer backbone while the imide block contains an arylene ketone segment similar to that in the arylene ether block and has been named LaRC-ITPI. A series of imide/arylene ether block and segmented copolymers were prepared and characterized. Films were prepared from these copolymers and mechanical properties were measured.

  14. Formation of interconnected morphologies via nanorod inclusion in the confined assembly of symmetric block copolymers.

    PubMed

    Park, Jay Hoon; Joo, Yong Lak

    2014-05-21

    We have investigated the effect of nanorods on the symmetry breaking of a model diblock copolymer under cylindrical confinement using coarse-grained molecular dynamics. Unlike nanoparticles, nanorods can readily be interconnected with each other and also induce connection across self-assembly domains at much lower loading than nanoparticles. Such interconnecting nanorods, when incorporated within the nanofiber confined assembled block copolymer, have great potential for providing highly conductive pathways for energy applications, such as battery electrodes and separators. Symmetric block copolymers (BCP) under cylindrical confinement with a nanorod aspect ratio (N) of 1, 5, and 10 are examined with three different types of nanorod-BCP attractions: (a) neutral nanorods, (b) A (wall-attractive phase)-attractive nanorods, and (c) B (wall-repulsive phase)-attractive nanorods. The system was studied with both selective and neutral walls, which affect the orientation of the interconnected nanorod network. Upon close examination of the BCP-nanorod self-assembly, we discovered that the ratio of the interphase distance to the nanorod aspect ratio (I/N) can be correlated to the onset of nanorod interconnectivity and formation of asymmetrical interconnected BCP morphology. By developing a phase diagram with respect to I/N, one can predict the formation of desired BCP morphology and the critical loading of nanorods for connected morphologies in cylindrical confinement. PMID:24682243

  15. Block Copolymers with a Twist

    SciTech Connect

    Ho, R.; Chiang, Y; Chen, C; Wang, H; Hasegawa, H; Akasaka, S; Thomas, E; Burger, C; Hsiao, B

    2009-01-01

    Chiral block copolymers (BCPs*) comprising chiral entities were designed to fabricate helical architectures (i.e., twisted morphologies) from self-assembly. A new helical phase (H*) with P622 symmetry was discovered in the self-assembly of poly(styrene)-b-poly(l-lactide) (PS-PLLA) BCPs*. Hexagonally packed, interdigitated PLLA helical microdomains in a PS matrix were directly visualized by electron tomography. The phase diagram of the PS-PLLA BCPs* was also established. Phase transitions from the H* phase to the stable cylinder and gyroid phases were found after long-time annealing, suggesting that the H* is a long-lived metastable phase. In contrast to racemic poly(styrene)-b-poly(d,l-lactide) BCPs, chiral interaction significantly enhances the incompatibility between achiral PS and chiral PLLA blocks in the PS-PLLA BCPs* and can be estimated through the determination of the interaction parameter.

  16. Arbitrary lattice symmetries via block copolymer nanomeshes

    PubMed Central

    Majewski, Pawel W.; Rahman, Atikur; Black, Charles T.; Yager, Kevin G.

    2015-01-01

    Self-assembly of block copolymers is a powerful motif for spontaneously forming well-defined nanostructures over macroscopic areas. Yet, the inherent energy minimization criteria of self-assembly give rise to a limited library of structures; diblock copolymers naturally form spheres on a cubic lattice, hexagonally packed cylinders and alternating lamellae. Here, we demonstrate multicomponent nanomeshes with any desired lattice symmetry. We exploit photothermal annealing to rapidly order and align block copolymer phases over macroscopic areas, combined with conversion of the self-assembled organic phase into inorganic replicas. Repeated photothermal processing independently aligns successive layers, providing full control of the size, symmetry and composition of the nanoscale unit cell. We construct a variety of symmetries, most of which are not natively formed by block copolymers, including squares, rhombuses, rectangles and triangles. In fact, we demonstrate all possible two-dimensional Bravais lattices. Finally, we elucidate the influence of nanostructure on the electrical and optical properties of nanomeshes. PMID:26100566

  17. Block copolymer structures in nano-pores

    NASA Astrophysics Data System (ADS)

    Pinna, Marco; Guo, Xiaohu; Zvelindovsky, Andrei

    2010-03-01

    We present results of coarse-grained computer modelling of block copolymer systems in cylindrical and spherical nanopores on Cell Dynamics Simulation. We study both cylindrical and spherical pores and systematically investigate structures formed by lamellar, cylinders and spherical block copolymer systems for various pore radii and affinity of block copolymer blocks to the pore walls. The obtained structures include: standing lamellae and cylinders, ``onions,'' cylinder ``knitting balls,'' ``golf-ball,'' layered spherical, ``virus''-like and mixed morphologies with T-junctions and U-type defects [1]. Kinetics of the structure formation and the differences with planar films are discussed. Our simulations suggest that novel porous nano-containers can be formed by confining block copolymers in pores of different geometries [1,2]. [4pt] [1] M. Pinna, X. Guo, A.V. Zvelindovsky, Polymer 49, 2797 (2008).[0pt] [2] M. Pinna, X. Guo, A.V. Zvelindovsky, J. Chem. Phys. 131, 214902 (2009).

  18. Phase behaviors of cyclic diblock copolymers.

    PubMed

    Zhang, Guojie; Fan, Zhongyong; Yang, Yuliang; Qiu, Feng

    2011-11-01

    A spectral method of self-consistent field theory has been applied to AB cyclic block copolymers. Phase behaviors of cyclic diblock copolymers, such as order-disorder transition, order-order transition, and domain spacing size, have been studied, showing good consistency with previous experimental and theoretical results. Compared to linear diblocks, cyclic diblocks are harder to phase separate due to the topological constraint of the ring structure. A direct disorder-to-cylinder transition window is observed in the phase diagram, which is significantly different from the mean field phase diagram of linear diblock copolymers. The domain spacing size ratio between cyclic and linear diblock copolymers is typically close to 0.707, indicating in segregation that the cyclic polymer can be considered to be made up of linear diblocks with half of the original chain length. PMID:22070321

  19. Electrostatic control of block copolymer morphology

    NASA Astrophysics Data System (ADS)

    Sing, Charles E.; Zwanikken, Jos W.; Olvera de La Cruz, Monica

    2014-07-01

    Energy storage is at present one of the foremost issues society faces. However, material challenges now serve as bottlenecks in technological progress. Lithium-ion batteries are the current gold standard to meet energy storage needs; however, they are limited owing to the inherent instability of liquid electrolytes. Block copolymers can self-assemble into nanostructures that simultaneously facilitate ion transport and provide mechanical stability. The ions themselves have a profound, yet previously unpredictable, effect on how these nanostructures assemble and thus the efficiency of ion transport. Here we demonstrate that varying the charge of a block copolymer is a powerful mechanism to predictably tune nanostructures. In particular, we demonstrate that highly asymmetric charge cohesion effects can induce the formation of nanostructures that are inaccessible to conventional uncharged block copolymers, including percolated phases desired for ion transport. This vastly expands the design space for block copolymer materials and is informative for the versatile design of battery electrolyte materials.

  20. Hydrotropic polymeric mixed micelles based on functional hyperbranched polyglycerol copolymers as hepatoma-targeting drug delivery system.

    PubMed

    Zhang, Xuejiao; Zhang, Xinge; Yu, Peien; Han, Yucai; Li, Yangguang; Li, Chaoxing

    2013-01-01

    Mixed copolymer nanoparticles (NPs) self-assembled from β-cyclodextrin-grafted hyperbranched polyglycerol (HPG-g-CD) and lactobionic acid (LA)-grafted hyperbranched polyglycerol (HPG-g-LA) were applied as carriers for a hydrophobic antitumor drug, paclitaxel (PTX), achieving hepatocellular carcinoma-targeted delivery. The resulting NPs exhibited high drug loading capacity and substantial stability in aqueous solution. In vitro drug release studies demonstrated a controlled drug release profile with increased release at acidic pH. Remarkably, tumor proliferation assays showed that PTX-loaded mixed copolymer NPs inhibited asialoglycoprotein (ASGP) receptor positive HepG2 cell proliferation in a concentration-dependent manner in comparison with ASGP receptor negative BGC-823 cells. Moreover, the competition assay demonstrated that the small molecular LA inhibited the cellular uptake of the PTX-loaded mixed copolymer NPs, indicating the ASGP receptor-mediated endocytosis in HepG2 cells. In addition, the intracellular uptake tests by confocal laser scanning microscopy showed that the mixed copolymer NPs were more efficiently taken up by HepG2 cells compared with HPG-g-CD NPs. These results suggest a feasible application of the mixed copolymer NPs as nanocarriers for hepatoma-targeted delivery of potent antitumor drugs. PMID:23132353

  1. Method for making block siloxane copolymers

    DOEpatents

    Butler, Nora; Jessop, Edward S.; Kolb, John R.

    1982-01-01

    A method for synthesizing block polysiloxane copolymers. Diorganoscyclosiloxanes and an end-blocking compound are interacted in the presence of a ring opening polymerization catalyst, producing a blocked prepolymer. The prepolymer is then interacted with a silanediol, resulting in condensation polymerization of the prepolymers. A second end-blocking compound is subsequently introduced to end-cap the polymers and copolymers formed from the condensation polymerization.

  2. Method for making block siloxane copolymers

    DOEpatents

    Butler, N.L.; Jessop, E.S.; Kolb, J.R.

    1981-02-25

    A method for synthesizing block polysiloxane copolymers is disclosed. Diorganoscyclosiloxanes and an end-blocking compound are interacted in the presence of a ring opening polymerization catalyst, producing a blocked prepolymer. The prepolymer is then interacted with a silanediol, resulting in condensation polymerization of the prepolymers. A second end-blocking compound is subsequently introduced to end-cap the polymers and copolymers formed from the condensation polymerization.

  3. Responsive Copolymers for Enhanced Petroleum Recovery

    SciTech Connect

    McCormick, C.; Hester, R.

    2001-02-27

    The objectives of this work was to: synthesize responsive copolymer systems; characterize molecular structure and solution behavior; measure rheological properties of aqueous fluids in fixed geometry flow profiles; and to tailor final polymer compositions for in situ rheology control under simulated conditions. This report focuses on the synthesis and characterization of novel stimuli responsive copolymers, the investigation of dilute polymer solutions in extensional flow and the design of a rheometer capable of measuring very dilute aqueous polymer solutions at low torque.

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

    PubMed

    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. PMID:25974198

  5. Molecular simulations of assembly of functionalized spherical nanoparticles

    NASA Astrophysics Data System (ADS)

    Seifpour, Arezou

    Precise assembly of nanoparticles is crucial for creating spatially engineered materials that can be used for photonics, photovoltaic, and metamaterials applications. One way to control nanoparticle assembly is by functionalizing the nanoparticle with ligands, such as polymers, DNA, and proteins, that can manipulate the interactions between the nanoparticles in the medium the particles are placed in. This thesis research aims to design ligands to provide a new route to the programmable assembly of nanoparticles. We first investigate using Monte Carlo simulation the effect of copolymer ligands on nanoparticle assembly. We first study a single nanoparticle grafted with many copolymer chains to understand how monomer sequence (e.g. alternating ABAB, or diblock AxBx) and chemistry of the copolymers affect the grafted chain conformation at various particle diameters, grafting densities, copolymer chain lengths, and monomer-monomer interactions in an implicit small molecule solvent. We find that the size of the grafted chain varies non-monotonically with increasing blockiness of the monomer sequence for a small particle diameter. From this first study, we selected the two sequences with the most different chain conformations---alternating and diblock---and studied the effect of the sequence and a range of monomer chemistries of the copolymer on the characteristics of assembly of multiple copolymer-functionalized nanoparticles. We find that the alternating sequence produces nanoclusters that are relatively isotropic, whereas diblock sequence tends to form anisotropic structures that are smaller and more compact when the block closer to the surface is attractive and larger loosely held together clusters when the outer block is attractive. Next, we conduct molecular dynamics simulations to study the effect of DNA ligands on nanoparticle assembly. Specifically we investigate the effect of grafted DNA strand composition (e.g. G/C content, placement and sequence) and

  6. Polycatechol Nanoparticle MRI Contrast Agents.

    PubMed

    Li, Yiwen; Huang, Yuran; Wang, Zhao; Carniato, Fabio; Xie, Yijun; Patterson, Joseph P; Thompson, Matthew P; Andolina, Christopher M; Ditri, Treffly B; Millstone, Jill E; Figueroa, Joshua S; Rinehart, Jeffrey D; Scadeng, Miriam; Botta, Mauro; Gianneschi, Nathan C

    2016-02-01

    Amphiphilic triblock copolymers containing Fe(III) -catecholate complexes formulated as spherical- or cylindrical-shaped micellar nanoparticles (SMN and CMN, respectively) are described as new T1-weighted agents with high relaxivity, low cytotoxicity, and long-term stability in biological fluids. Relaxivities of both SMN and CMN exceed those of established gadolinium chelates across a wide range of magnetic field strengths. Interestingly, shape-dependent behavior is observed in terms of the particles' interactions with HeLa cells, with CMN exhibiting enhanced uptake and contrast via magnetic resonance imaging (MRI) compared with SMN. These results suggest that control over soft nanoparticle shape will provide an avenue for optimization of particle-based contrast agents as biodiagnostics. The polycatechol nanoparticles are proposed as suitable for preclinical investigations into their viability as gadolinium-free, safe, and effective imaging agents for MRI contrast enhancement. PMID:26681255

  7. Macromolecular Brushes as Stabilizers of Hydrophobic Solute Nanoparticles.

    PubMed

    Luo, Hanying; Raciti, David; Wang, Chao; Herrera-Alonso, Margarita

    2016-06-01

    Macromolecular brushes bearing poly(ethylene glycol) and poly(d,l-lactide) side chains were used to stabilize hydrophobic solute nanoparticles formed by a rapid change in solvent quality. Unlike linear diblock copolymers with the same hydrophilic and hydrophobic block chemistries, the brush copolymer enabled the formation of ellipsoidal β-carotene nanoparticles, which in cosolvent mixtures developed into rod-like structures, resulting from a combination of Ostwald ripening and particle aggregation. The stabilizing ability of the copolymer was highly dependent on the mobility of the hydrophobic component, influenced by its molecular weight. As shown here, asymmetric amphiphilic macromolecular brushes of this type may be used as hydrophobic drug stabilizers and potentially assist the shape control of nonspherical aggregate morphologies. PMID:27035279

  8. Structure-directing star-shaped block copolymers: supramolecular vesicles for the delivery of anticancer drugs.

    PubMed

    Yang, Chuan; Liu, Shao Qiong; Venkataraman, Shrinivas; Gao, Shu Jun; Ke, Xiyu; Chia, Xin Tian; Hedrick, James L; Yang, Yi Yan

    2015-06-28

    Amphiphilic polycarbonate/PEG copolymer with a star-like architecture was designed to facilitate a unique supramolecular transformation of micelles to vesicles in aqueous solution for the efficient delivery of anticancer drugs. The star-shaped amphipilic block copolymer was synthesized by initiating the ring-opening polymerization of trimethylene carbonate (TMC) from methyl cholate through a combination of metal-free organo-catalytic living ring-opening polymerization and post-polymerization chain-end derivatization strategies. Subsequently, the self-assembly of the star-like polymer in aqueous solution into nanosized vesicles for anti-cancer drug delivery was studied. DOX was physically encapsulated into vesicles by dialysis and drug loading level was significant (22.5% in weight) for DOX. Importantly, DOX-loaded nanoparticles self-assembled from the star-like copolymer exhibited greater kinetic stability and higher DOX loading capacity than micelles prepared from cholesterol-initiated diblock analogue. The advantageous disparity is believed to be due to the transformation of micelles (diblock copolymer) to vesicles (star-like block copolymer) that possess greater core space for drug loading as well as the ability of such supramolecular structures to encapsulate DOX. DOX-loaded vesicles effectively inhibited the proliferation of 4T1, MDA-MB-231 and BT-474 cells, with IC50 values of 10, 1.5 and 1.0mg/L, respectively. DOX-loaded vesicles injected into 4T1 tumor-bearing mice exhibited enhanced accumulation in tumor tissue due to the enhanced permeation and retention (EPR) effect. Importantly, DOX-loaded vesicles demonstrated greater tumor growth inhibition than free DOX without causing significant body weight loss or cardiotoxicity. The unique ability of the star-like copolymer emanating from the methyl cholate core provided the requisite modification in the block copolymer interfacial curvature to generate vesicles of high loading capacity for DOX with significant

  9. Single-molecule protein arrays enabled by scanning probe block copolymer lithography.

    PubMed

    Chai, Jinan; Wong, Lu Shin; Giam, Louise; Mirkin, Chad A

    2011-12-01

    The ability to control the placement of individual protein molecules on surfaces could enable advances in a wide range of areas, from the development of nanoscale biomolecular devices to fundamental studies in cell biology. Such control, however, remains a challenge in nanobiotechnology due to the limitations of current lithographic techniques. Herein we report an approach that combines scanning probe block copolymer lithography with site-selective immobilization strategies to create arrays of proteins down to the single-molecule level with arbitrary pattern control. Scanning probe block copolymer lithography was used to synthesize individual sub-10-nm single crystal gold nanoparticles that can act as scaffolds for the adsorption of functionalized alkylthiol monolayers, which facilitate the immobilization of specific proteins. The number of protein molecules that adsorb onto the nanoparticles is dependent upon particle size; when the particle size approaches the dimensions of a protein molecule, each particle can support a single protein. This was demonstrated with both gold nanoparticle and quantum dot labeling coupled with transmission electron microscopy imaging experiments. The immobilized proteins remain bioactive, as evidenced by enzymatic assays and antigen-antibody binding experiments. Importantly, this approach to generate single-biomolecule arrays is, in principle, applicable to many parallelized cantilever and cantilever-free scanning probe molecular printing methods. PMID:22106270

  10. Ion and temperature sensitive polypeptide block copolymer.

    PubMed

    Joo, Jae Hee; Ko, Du Young; Moon, Hyo Jung; Shinde, Usha Pramod; Park, Min Hee; Jeong, Byeongmoon

    2014-10-13

    A poly(ethylene glycol)/poly(L-alanine) multiblock copolymer incorporating ethylene diamine tetraacetic acid ([PA-PEG-PA-EDTA(m)) was synthesized as an ion/temperature dual stimuli-sensitive polymer, where the effect of different metal ions (Cu(2+), Zn(2+), and Ca(2+)) on the thermogelation of the polymer aqueous solution was investigated. The dissociation constants between the metal ions and the multiblock copolymer were calculated to be 1.2 × 10(-7), 6.6 × 10(-6), and 1.2 × 10(-4) M for Cu(2+), Zn(2+), and Ca(2+), respectively, implying that the binding affinity of the multiblock copolymer for Cu(2+) is much greater than that for Zn(2+) or Ca(2+). Atomic force microscopy and dynamic light scattering of the multiblock copolymer containing metal ions suggested micelle formation at low temperature, which aggregated as the temperature increased. Circular dichroism spectra suggested that changes in the α-helical secondary structure of the multiblock copolymer were more pronounced by adding Cu(2+) than other metal ions. The thermogelation of the multiblock copolymer aqueous solution containing Cu(2+) was observed at a lower temperature, and the modulus of the gel was significantly higher than that of the system containing Ca(2+) or Zn(2+), in spite of the same concentration of the metal ions and their same ionic valence of +2. The above results suggested that strong ionic complexes between Cu(2+) and the multiblock copolymer not only affected the secondary structure of the polymer but also facilitated the thermogelation of the polymer aqueous solution through effective salt-bridge formation even in a millimolar range of the metal ion concentration. Therefore, binding affinity of metal ions for polymers should be considered first in designing an effective ion/temperature dual stimuli-sensitive polymer. PMID:25178662

  11. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... vinyl chloride homo- or copolymers. (e) Conditions of use. The n-alkylglutarimide/acrylic copolymers are used as articles or components of articles (other than articles composed of vinyl chloride homo-...

  12. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... vinyl chloride homo- or copolymers. (e) Conditions of use. The n-alkylglutarimide/acrylic copolymers are used as articles or components of articles (other than articles composed of vinyl chloride homo-...

  13. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... vinyl chloride homo- or copolymers. (e) Conditions of use. The n-alkylglutarimide/acrylic copolymers are used as articles or components of articles (other than articles composed of vinyl chloride homo-...

  14. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... vinyl chloride homo- or copolymers. (e) Conditions of use. The n-alkylglutarimide/acrylic copolymers are used as articles or components of articles (other than articles composed of vinyl chloride homo-...

  15. Initiator Effects in Reactive Extrusion of Starch Graft Copolymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Graft copolymers of starch with water-soluble polymers such as polyacrylamide have potential applications including hydrogels, superabsorbents, and thickening agents. Reactive extrusion is a rapid, continuous method for production of starch graft copolymers with high reaction and grafting efficienc...

  16. Hydrogen-bonded aggregates in precise acid copolymers

    SciTech Connect

    Lueth, Christopher A.; Bolintineanu, Dan S.; Stevens, Mark J. Frischknecht, Amalie L.

    2014-02-07

    We perform atomistic molecular dynamics simulations of melts of four precise acid copolymers, two poly(ethylene-co-acrylic acid) (PEAA) copolymers, and two poly(ethylene-co-sulfonic acid) (PESA) copolymers. The acid groups are spaced by either 9 or 21 carbons along the polymer backbones. Hydrogen bonding causes the acid groups to form aggregates. These aggregates give rise to a low wavevector peak in the structure factors, in agreement with X-ray scattering data for the PEAA materials. The structure factors for the PESA copolymers are very similar to those for the PEAA copolymers, indicating a similar distance between aggregates which depends on the spacer length but not on the nature of the acid group. The PEAA copolymers are found to form more dimers and other small aggregates than do the PESA copolymers, while the PESA copolymers have both more free acid groups and more large aggregates.

  17. Diblock Copolymers for Nanoscale Patterning

    NASA Astrophysics Data System (ADS)

    Russell, Thomas

    2006-03-01

    As the size scale of device features becomes increasingly smaller, conventional lithographic processes become increasingly more difficult and expensive, especially at a minimum feature size of less than 50 nm. Consequently, to achieve higher density circuits, storage devices or displays, it is evident that alternative routes need to be developed to circumvent both cost and manufacturing issues. An ideal process would be compatible with existing technological processes/manufacturing techniques and these strategies, together with novel materials, could allow significant advances to be made in meeting both short-term and long-term demands for higher density and faster devices. The self-assembly of block copolymers (BCP), two polymer chains covalently linked together at one end, provides a robust solution to these challenges. As thin films, immiscible BCP self-assemble into a range of highly-ordered morphologies where with size scale of the features is limited to the size of the polymers chains and are, therefore, nanoscopic in size. While self-assembly alone is sufficient for a number of applications in fabricating advanced microelectronics, directed self-orienting self-assembly processes are also required to produce complex devices with the required density and addressability of elements to meet future demands. By combining tailored self-assembly processes, a bottom-up approach, with micro-fabrication processes, a top-down approach, the ever-present thirst of the consumer for faster, better and cheaper devices can be met in very simple, yet robust, ways.

  18. Random Copolymer: Gaussian Variational Approach

    NASA Astrophysics Data System (ADS)

    Moskalenko, A.; Kuznetsov, Yu. A.; Dawson, K. A.

    1997-03-01

    We study the phase transitions of a random copolymer chain with quenched disorder. We calculate the average over the quenched disorder in replica space and apply a Gaussian variational approach based on a generic quadratic trial Hamiltonian in terms of the correlation functions of monomer Fourier coordinates. This has the advantage that it allows us to incorporate fluctuations of the density, determined self-consistently, and to study collapse, phase separation transitions and the onset of the freezing transition within the same mean field theory. The effective free energy of the system is derived analytically and analyzed numerically in the one-step Parisi scheme. Such quantities as the radius of gyration, end-to-end distance or the average value of the overlap between different replicas are treated as observables and evaluated by introducing appropriate external fields to the Hamiltonian. As a result we obtain the phase diagram in terms of model parameters, scaling for the freezing transition and the dependence of correlation functions on the chain index.

  19. Cobalt silica magnetic nanoparticles with functional surfaces

    NASA Astrophysics Data System (ADS)

    Vadala, Michael L.; Zalich, Michael A.; Fulks, David B.; St. Pierre, Tim G.; Dailey, James P.; Riffle, Judy S.

    2005-05-01

    Cobalt nanoparticles encased in polysiloxane block copolymers have been heated at 600-700 °C to form protective shells around the particles, which contain crosslinked Si-O structures, and to anneal the cobalt. Methods to functionalize and modify the surfaces of the pyrolyzed/annealed silica-cobalt complexes with amines, isocyanates, poly(ethylene oxide), poly( L-lactide) and polydimethylsiloxane (PDMS) are presented.

  20. Dynamic Processes in Diblock Copolymer Micelles

    NASA Astrophysics Data System (ADS)

    Robertson, Megan; Singh, Avantika

    2013-03-01

    Diblock copolymers, which form micelle structures in selective solvents, offer advantages of robustness and tunability of micelle characteristics as compared to small molecule surfactants. Diblock copolymer micelles in water have been a subject of great interest in drug delivery applications based on their high loading capacity and targeted drug delivery. The aim of this work is to understand the dynamic processes which underlie the self-assembly of diblock copolymer micelle systems which have a semi-crystalline core. Due to the large size of the molecules, the self-assembly of block copolymer micelles occurs on significantly longer time scales than small molecule analogues. The present work focuses on amphiphilic diblock copolymers containing blocks of poly(ethylene oxide) (a hydrophilic polymer) and polycaprolactone (a hydrophobic, semi-crystalline polymer), which spontaneously self-assemble into spherical micelles in water. A variety of experimental techniques are used to probe the kinetic processes relevant to micelle self-assembly, including time-resolved neutron scattering, dynamic light scattering, pulsed field gradient nuclear magnetic resonance, and fluorescence resonance energy transfer experiments.

  1. Patterned Diblock Co-Polymer Thin Films as Templates for Advanced Anisotropic Metal Nanostructures.

    PubMed

    Roth, Stephan V; Santoro, Gonzalo; Risch, Johannes F H; Yu, Shun; Schwartzkopf, Matthias; Boese, Torsten; Döhrmann, Ralph; Zhang, Peng; Besner, Bastian; Bremer, Philipp; Rukser, Dieter; Rübhausen, Michael A; Terrill, Nick J; Staniec, Paul A; Yao, Yuan; Metwalli, Ezzeldin; Müller-Buschbaum, Peter

    2015-06-17

    We demonstrate glancing-angle deposition of gold on a nanostructured diblock copolymer, namely polystyrene-block-poly(methyl methacrylate) thin film. Exploiting the selective wetting of gold on the polystyrene block, we are able to fabricate directional hierarchical structures. We prove the asymmetric growth of the gold nanoparticles and are able to extract the different growth laws by in situ scattering methods. The optical anisotropy of these hierarchical hybrid materials is further probed by angular resolved spectroscopic methods. This approach enables us to tailor functional hierarchical layers in nanodevices, such as nanoantennae arrays, organic photovoltaics, and sensor electronics. PMID:25635697

  2. Targeted drug delivery nanosystems based on copolymer poly(lactide)-tocopheryl polyethylene glycol succinate for cancer treatment

    NASA Astrophysics Data System (ADS)

    Thu Ha, Phuong; Nguyen, Hoai Nam; Doan Do, Hai; Thong Phan, Quoc; Nguyet Tran Thi, Minh; Phuc Nguyen, Xuan; Nhung Hoang Thi, My; Huong Le, Mai; Nguyen, Linh Toan; Quang Bui, Thuc; Hieu Phan, Van

    2016-03-01

    Along with the development of nanotechnology, drug delivery nanosystems (DDNSs) have attracted a great deal of concern among scientists over the world, especially in cancer treatment. DDNSs not only improve water solubility of anticancer drugs but also increase therapeutic efficacy and minimize the side effects of treatment methods through targeting mechanisms including passive and active targeting. Passive targeting is based on the nano-size of drug delivery systems while active targeting is based on the specific bindings between targeting ligands attached on the drug delivery systems and the unique receptors on the cancer cell surface. In this article we present some of our results in the synthesis and testing of DDNSs prepared from copolymer poly(lactide)-tocopheryl polyethylene glycol succinate (PLA-TPGS), which carry anticancer drugs including curcumin, paclitaxel and doxorubicin. In order to increase the targeting effect to cancer cells, active targeting ligand folate was attached to the DDNSs. The results showed copolymer PLA-TPGS to be an excellent carrier for loading hydrophobic drugs (curcumin and paclitaxel). The fabricated DDNSs had a very small size (50-100 nm) and enhanced the cellular uptake and cytotoxicity of drugs. Most notably, folate-decorated paclitaxel-loaded copolymer PLA-TPGS nanoparticles (Fol/PTX/PLA-TPGS NPs) were tested on tumor-bearing nude mice. During the treatment time, Fol/PTX/PLA-TPGS NPs always exhibited the best tumor growth inhibition compared to free paclitaxel and paclitaxel-loaded copolymer PLA-TPGS nanoparticles. All results evidenced the promising potential of copolymer PLA-TPGS in fabricating targeted DDNSs for cancer treatment.

  3. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylate ester copolymer coating. 175.210 Section... COATINGS Substances for Use as Components of Coatings § 175.210 Acrylate ester copolymer coating. Acrylate ester copolymer coating may safely be used as a food-contact surface of articles intended for...

  4. pH-sensitive methacrylic copolymers and the production thereof

    DOEpatents

    Mallapragada, Surya K.; Anderson, Brian C.; Bloom, Paul D.; Sheares Ashby, Valerie V.

    2006-02-14

    The present invention provides novel multi-functional methacrylic copolymers that exhibit cationic pH-sensitive behavior as well as good water solubility under acidic conditions. The copolymers are constructed from tertiary amine methacrylates and poly(ethylene glycol) containing methacrylates. The copolymers are useful as gene vectors, pharmaceutical carriers, and in protein separation applications.

  5. 21 CFR 177.1820 - Styrene-maleic anhydride copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... sieve No. 20. 2. Styrene-maleic anhydride copolymer modified with butadiene, (CAS Reg. No. 27288-99-9... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Styrene-maleic anhydride copolymers. 177.1820... Use Food Contact Surfaces § 177.1820 Styrene-maleic anhydride copolymers. Styrene-maleic...

  6. 21 CFR 177.1820 - Styrene-maleic anhydride copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... units by weight and not more than 20 percent styrene-butadiene and/or butadiene rubber units by weight... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Styrene-maleic anhydride copolymers. 177.1820... copolymers. Styrene-maleic anhydride copolymers identified in paragraph (a) of this section may be...

  7. 21 CFR 177.1820 - Styrene-maleic anhydride copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... units by weight and not more than 20 percent styrene-butadiene and/or butadiene rubber units by weight... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Styrene-maleic anhydride copolymers. 177.1820... copolymers. Styrene-maleic anhydride copolymers identified in paragraph (a) of this section may be...

  8. pH-sensitive methacrylic copolymers and the production thereof

    DOEpatents

    Mallapragada, Surya K.; Anderson, Brian C.; Bloom, Paul D.; Sheares Ashby, Valerie V.

    2007-01-09

    The present invention provides novel multi-functional methacrylic copolymers that exhibit cationic pH-sensitive behavior as well as good water solubility under acidic conditions. The copolymers are constructed from tertiary amine methacrylates and poly(ethylene glycol) containing methacrylates. The copolymers are useful as gene vectors, pharmaceutical carriers, and in protein separation applications.

  9. 40 CFR 721.484 - Fluorinated acrylic copolymer (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Fluorinated acrylic copolymer (generic... Specific Chemical Substances § 721.484 Fluorinated acrylic copolymer (generic name). (a) Chemical substance... fluorinated acrylic copolymer (PMN P-95-1208) is subject to reporting under this section for the...

  10. 40 CFR 721.484 - Fluorinated acrylic copolymer (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Fluorinated acrylic copolymer (generic... Specific Chemical Substances § 721.484 Fluorinated acrylic copolymer (generic name). (a) Chemical substance... fluorinated acrylic copolymer (PMN P-95-1208) is subject to reporting under this section for the...

  11. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the...

  12. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Methacrylic acid-divinylbenzene copolymer. 172.775... Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may... produced by the polymerization of methacrylic acid and divinylbenzene. The divinylbenzene functions as...

  13. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the...

  14. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be...

  15. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be...

  16. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the...

  17. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be...

  18. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be...

  19. 21 CFR 173.60 - Dimethylamine-epichlorohydrin copolymer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Dimethylamine-epichlorohydrin copolymer. 173.60... HUMAN CONSUMPTION Polymer Substances and Polymer Adjuvants for Food Treatment § 173.60 Dimethylamine-epichlorohydrin copolymer. Dimethylamine-epichlorohydrin copolymer (CAS Reg. No. 25988-97-0) may be safely used...

  20. 21 CFR 173.60 - Dimethylamine-epichlorohydrin copolymer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Dimethylamine-epichlorohydrin copolymer. 173.60... HUMAN CONSUMPTION Polymer Substances and Polymer Adjuvants for Food Treatment § 173.60 Dimethylamine-epichlorohydrin copolymer. Dimethylamine-epichlorohydrin copolymer (CAS Reg. No. 25988-97-0) may be safely used...

  1. 21 CFR 173.60 - Dimethylamine-epichlorohydrin copolymer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Dimethylamine-epichlorohydrin copolymer. 173.60... HUMAN CONSUMPTION Polymer Substances and Polymer Adjuvants for Food Treatment § 173.60 Dimethylamine-epichlorohydrin copolymer. Dimethylamine-epichlorohydrin copolymer (CAS Reg. No. 25988-97-0) may be safely used...

  2. Theranostic nanoparticles for the treatment of cancer

    NASA Astrophysics Data System (ADS)

    Moore, Thomas Lee

    The main focus of this research was to evaluate the ability of a novel multifunctional nanoparticle to mediate drug delivery and enable a non-invasive approach to measure drug release kinetics in situ for the treatment of cancer. These goals were approached by developing a nanoparticle consisting of an inorganic core (i.e. gadolinium sulfoxide doped with europium ions or carbon nanotubes). This was coated with an external amphiphilic polymer shell comprised of a biodegradable polyester (i.e. poly(lactide) or poly(glycolide)), and poly(ethylene glycol) block copolymer. In this system, the inorganic core mediates the imaging aspect, the relatively hydrophobic polyester encapsulates hydrophobic anti-cancer drugs, and poly(ethylene glycol) stabilizes the nanoparticle in an aqueous environment. The synthesis of this nanoparticle drug delivery system utilized a simple one-pot room temperature ring-opening polymerization that neglected the use of potentially toxic catalysts and reduced the number of washing steps. This functionalization approach could be applied across a number of inorganic nanoparticle platforms. Coating inorganic nanoparticles with biodegradable polymer was shown to decrease in vitro and in vivo toxicity. Nanoparticles could be further coated with multiple polymer layers to better control drug release characteristics. Finally, loading polymer coated radioluminescent nanoparticles with photoactive drugs enabled a mechanism for measuring drug concentration in situ. The work presented here represents a step forward to developing theranostic nanoparticles that can improve the treatment of cancer.

  3. Block copolymer blend phase behavior: Binary diblock blends and amphiphilic block copolymer/epoxy mixtures

    NASA Astrophysics Data System (ADS)

    Lipic, Paul Martin

    The phase behavior of block copolymers and block copolymer blends has provided an extensive amount of exciting research and industrial applications for over thirty years. However, the unique nanoscale morphologies of microphase separated block copolymer systems is still not completely understood. This thesis examines the phase behavior of diblock copolymers and binary diblock copolymer blends in the strong segregation limit (SSL), and blends of an amphiphilic diblock copolymer with an epoxy resin. Studies of high molecular weight (˜84,000 g/mole) poly(ethylene)-poly(ethyl ethylene) (PE-PEE) diblock copolymers probed the ability of block copolymers to reach equilibrium in the SSL. Samples of pure diblocks or binary diblock blends prepared using different preparation techniques (solvent casting or precipitation) had different phase behaviors, as identified with transmission electron microscopy (TEM) and small-angle x-ray scattering (SAXS), confirming non-equilibrium phase behavior. This non-equilibrium behavior was metastable, and these results identify the caution that should be used when claiming equilibrium phase behavior in the SSL. Blends of an amphiphilic diblock copolymer, poly(ethylene oxide)-poly(ethylene-alt-propylene) (PEO-PEP) with a polymerizable epoxy resin selectively miscible with PEO, poly(Bisphenol-A-co-epichlorohydrin), supported theoretical calculations and increased the understanding of block copolymer/homopolymer blends. These blends formed different ordered structures (lamellae, bicontinuous cubic gyroid, hexagonally packed cylinders, cubic and hexagonally packed spheres) as well as a disordered spherical micellar structure, identified with SAXS and rheological measurements. Addition of hardener, methylene dianiline, to the system resulted in cross-linking of the epoxy resin and formation of a thermoset material. Macrophase separation between the epoxy and block copolymer did not occur, but local expulsion of the PEO from the epoxy was

  4. Thermodynamic Interactions in Organometallic Block Copolymers

    SciTech Connect

    Pople, John A

    2002-08-06

    The thermodynamic interactions in anionically synthesized poly(styrene-block-ferrocenyldimethylsilane) (SF) copolymers were examined using birefringence, small angle X-ray and neutron scattering (SAXS and SANS). We show that birefringence detection of the order-disorder transition is possible in colored samples provided the wavelength of the incident beam is in the tail of the absorption spectrum. The location of the order-disorder transition was confirmed by SAXS. The temperature-dependence of the Flory-Huggins parameter, {chi}, of SF copolymers, determined by SAXS, is similar in magnitude to that between polystyrene and polyisoprene chains. We find that {chi} is independent of block copolymer composition (within experimental error). We also demonstrate that the neutron scattering length densities of styrene and ferrocenyldimethylsilane moieties are identical due to a surprising cancellation of factors related to density and atomic composition.

  5. Rod-Coil Block Polyimide Copolymers

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B. (Inventor); Kinder, James D. (Inventor)

    2005-01-01

    This invention is a series of rod-coil block polyimide copolymers that are easy to fabricate into mechanically resilient films with acceptable ionic or protonic conductivity at a variety of temperatures. The copolymers consist of short-rigid polyimide rod segments alternating with polyether coil segments. The rods and coil segments can be linear, branched or mixtures of linear and branched segments. The highly incompatible rods and coil segments phase separate, providing nanoscale channels for ion conduction. The polyimide segments provide dimensional and mechanical stability and can be functionalized in a number of ways to provide specialized functions for a given application. These rod-coil black polyimide copolymers are particularly useful in the preparation of ion conductive membranes for use in the manufacture of fuel cells and lithium based polymer batteries.

  6. Graft copolymer separators — development and use

    NASA Astrophysics Data System (ADS)

    Lovell, K. V.; Adams, L. B.

    Graft copolymer membranes have been used for a number of years as interelectrode separators in alkaline batteries either singly, laminated to cellophane, or in conjunction with other materials such as felts. The preparation details of some of the Royal Military College of Science's copolymers are summarised with emphasis on the production of commercial quantities having a high degree of uniformity and reproducibility. Important properties in a battery environment are discussed and, where possible, compared with other separator materials; notably cellophane. The use of graft copolymers in a number of primary and secondary alkaline battery systems is reported and test data given. Conclusions are drawn relating the properties of these separators to their performance in cells.

  7. Polyimide nanofoams from aliphatic polyester based copolymers

    SciTech Connect

    Hedrick, J.L.; Carter, K.R.; Richter, R.; Russell, T.P.

    1996-10-01

    High temperature polymer foams were prepared using microphase separated block copolymers where the major component is thermally stable block and the minor component is thermally labile. Upon thermal treatment, the dispersed minor component undergoes thermolysis leaving pores the size and shape of which are dictated by the initial copolymer morphology. The driving force behind the survey of aliphatic polyesters as possible labile blocks stems from their quantitative degradation into low boiling, polar degradation products via a backbiting process. Block copolymers were prepared using either a monofunctional caprolactone or a valerolactone oligomer and a high T. polyimide. Microphase morphologies were observed in each case. Thermal decomposition of the polyester blocks was accomplished by a thermal treatment at 370{degrees}C for 5 h. Significant density reductions were measured, and the resulting foams showed pore sizes in the 60-70 {Angstrom} range.

  8. [Hydrodynamic properties of exopolysaccharide-acrylamide copolymer].

    PubMed

    Votselko, S K

    2000-01-01

    The method for producing copolymer EPAA of exopolysaccharide (EPS)--polyacrylamide (PAA) has been presented which was based on microbial exopolysaccharides (enposane, xampane), their mixture and model EPS (xanthane sigma, rodopol P-23). The copolymer was produced by acrylamide polymerization in 1-2% water solutions of polysaccharides, the concentration of acrylamide in the reaction mixture being 4.7-2% and that of polysaccharides 0.1-1% of the weight. Hydrodynamic parameters of the studied polymers have been determined, their heterogenity as to molecular-weight characteristics has been demonstrated. Molecular-weight distribution of copolymers showed that the content of low-molecular fractions decreased, thus the Mw values were (0.08-0.2) x 10(6) Da in contrast to that of exopolysaccharides possessing Mw (1.2-0.4) x 10(6) Da and of polyacrylamide possessing Mw within (2-30) x 10(6) Da. The value of efficient viscosity of copolymers ranged from 120 to 131 mPa.s that was lower than that of polyacrylamide (500 mPa.s), and higher than that of exopolysaccharides (42 mPa.s), and it depended on the sample, raw material, production conditions. A possibility has been shown to produce a new copolymer based on microbial polysaccharides enposane and xampane in the process of acrylamide polymerization. It has been found out that the studied copolymers EPAA differ from initial ones as to their hydrodynamical properties, which determines their preference: better solubility, good glueing properties, prolonged term of preservation, resistance to bacterial pollution. PMID:11300081

  9. Morphologies of poly(cyclohexadiene) diblock copolymers

    SciTech Connect

    Kumar, Rajeev; Mays, Jimmy; Sides, Scott; Goswami, Monojoy; Sumpter, Bobby G; Hong, Kunlun; Avgeropoulos, Apostolos; Russell, Thomas P; Gido, Samuel; Tsoukatos, Thodoris; Beyer, Fredrick

    2012-01-01

    Concerted experimental and theoretical investigations have been carried out to understand the micro-phase separation in diblock copolymer melts containing poly (1,3-cyclohexadiene), PCHD, as one of the constituents. In particular, we have studied diblock copolymer melts containing polystyrene (PS), polybutadiene (PB), and polyisoprene (PI) as the second block. We have systematically varied the ratio of 1,2- /1,4-microstructures of poly (1,3-cyclohexadiene) to tune the conformational asymmetry between the two blocks and characterized the effects of these changes on the morphologies using transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). Our experimental investigations reveal that the melts of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing nearly equal fractions of each component and high percentage of 1,4-microstructures in the PCHD block form cylindrical rather than lamellar morphologies as expected in symmetric diblock copolymers. In contrast, the morphologies of PCHD-b-PB, PCHD-b-PS and PCHD-b-PI containing PCHD block with higher 1,2-microstructure are found to be disordered at 110 C. The change in the morphological behavior is in good agreement with our numerical calculations using the random phase approximation and self-consistent field theory for conformationally asymmetric diblock copolymer melts. Also, the effects of composition fluctuations are studied by extending the Brazovskii-Leibler-Fredrickson-Helfand (J. Chem. Phys. 87, 697 (1987)) theory to conformationally asymmetric diblock copolymer melts. These results allow the understanding of the underlying self-assembly process that highlights the importance of the conformational asymmetry in tuning the morphologies in block copolymers.

  10. Preparation of transition metal nanoparticles and surfaces modified with (CO) polymers synthesized by RAFT

    DOEpatents

    McCormick, III, Charles L.; Lowe, Andrew B.; Sumerlin, Brent S.

    2006-10-25

    A new, facile, general one-phase method of generating thiol-functionalized transition metal nanoparticles and surface modified by (co)polymers synthesized by the RAFT method is described. The method includes the steps of forming a (co)polymer in aqueous solution using the RAFT methodology, forming a collidal transition metal precursor solution from an appropriate transition metal; adding the metal precursor solution or surface to the (co)polymer solution, adding a reducing agent into the solution to reduce the metal colloid in situ to produce the stabilized nanoparticles or surface, and isolating the stabilized nanoparticles or surface in a manner such that aggregation is minimized. The functionalized surfaces generated using these methods can further undergo planar surface modifications, such as fuctionalization with a variety of different chemical groups, expanding their utility and application.

  11. Microphase separation in a model graft copolymer

    SciTech Connect

    Dozier, W.D.; Thiyagarajan, P.; Peiffer, D.G.

    1993-10-01

    We present a preliminary overview of our work on a series of graft copolymers having poly(ethyl acrylate) backbones with pendant chains of polystyrene (PS). The copolymer system appeared to be in the strong segregation limit and exhibited evidence of ordered structures. The morphology of these structures can apparently be very different from what would be expected. For instance, we observed a lamellar structure in a material containing 28 wt.% PS grafts. Samples under uniaxial strain showed either conventional (i.e., affine deformation) and anomalous ({open_quotes}butterfly{close_quotes} isointensity patterns) behavior in small-angle neutron scattering.

  12. Substrate tolerant direct block copolymer nanolithography.

    PubMed

    Li, Tao; Wang, Zhongli; Schulte, Lars; Ndoni, Sokol

    2016-01-01

    Block copolymer (BC) self-assembly constitutes a powerful platform for nanolithography. However, there is a need for a general approach to BC lithography that critically considers all the steps from substrate preparation to the final pattern transfer. We present a procedure that significantly simplifies the main stream BC lithography process, showing a broad substrate tolerance and allowing for efficient pattern transfer over wafer scale. PDMS-rich poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) copolymers are directly applied on substrates including polymers, silicon and graphene. A single oxygen plasma treatment enables formation of the oxidized PDMS hard mask, PS block removal and polymer or graphene substrate patterning. PMID:26606904

  13. Co-polymer Films for Sensors

    NASA Technical Reports Server (NTRS)

    Ryan, Margaret A. (Inventor); Homer, Margie L. (Inventor); Yen, Shiao-Pin S. (Inventor); Kisor, Adam (Inventor); Jewell, April D. (Inventor); Shevade, Abhijit V. (Inventor); Manatt, Kenneth S. (Inventor); Taylor, Charles (Inventor); Blanco, Mario (Inventor); Goddard, William A. (Inventor)

    2012-01-01

    Embodiments include a sensor comprising a co-polymer, the co-polymer comprising a first monomer and a second monomer. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is polystyrene and the second monomer is poly-2-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium benzylamine chloride. Other embodiments are described and claimed.

  14. Co-polymer films for sensors

    NASA Technical Reports Server (NTRS)

    Ryan, Margaret A. (Inventor); Homer, Margie L. (Inventor); Yen, Shiao-Pin S. (Inventor); Kisor, Adam (Inventor); Jewell, April D. (Inventor); Shevade, Abhijit V. (Inventor); Manatt, Kenneth S. (Inventor); Taylor, Charles (Inventor); Blanco, Mario (Inventor); Goddard, William A. (Inventor)

    2010-01-01

    Embodiments include a sensor comprising a co-polymer, the co-polymer comprising a first monomer and a second monomer. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is polystyrene and the second monomer is poly-2-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium benzylamine chloride. Other embodiments are described and claimed.

  15. Tailor-made pentablock copolymer based formulation for sustained ocular delivery of protein therapeutics.

    PubMed

    Patel, Sulabh P; Vaishya, Ravi; Mishra, Gyan Prakash; Tamboli, Viral; Pal, Dhananjay; Mitra, Ashim K

    2014-01-01

    The objective of this research article is to report the synthesis and evaluation of novel pentablock copolymers for controlled delivery of macromolecules in the treatment of posterior segment diseases. Novel biodegradable PB copolymers were synthesized by sequential ring-opening polymerization. Various ratios and molecular weights of each block (polyglycolic acid, polyethylene glycol, polylactic acid, and polycaprolactone) were selected for synthesis and to optimize release profile of FITC-BSA, IgG, and bevacizumab from nanoparticles (NPs) and thermosensitive gel. NPs were characterized for particle size, polydispersity, entrapment efficiency, and drug loading. In vitro release study of proteins from NPs alone and composite formulation (NPs suspended in thermosensitive gel) was performed. Composite formulations demonstrated no or negligible burst release with continuous near zero-order release in contrast to NPs alone. Hydrodynamic diameter of protein therapeutics and hydrophobicity of PB copolymer exhibited significant effect on entrapment efficiency and in vitro release profile. CD spectroscopy confirmed retention of structural conformation of released protein. Biological activity of released bevacizumab was confirmed by in vitro cell proliferation and cell migration assays. It can be concluded that novel PB polymers can serve a platform for sustained delivery of therapeutic proteins. PMID:25045540

  16. Hierarchical assembly of block copolymer micelles into reversible networks: MC simulations

    NASA Astrophysics Data System (ADS)

    Wang, Zilu; Dormidontova, Elena

    2015-03-01

    The rapid development of nanoscience has considerably expanded the range of building blocks for complex self-assembled nanostructure formation, which show great potential for numerous advanced applications. We apply Monte Carlo simulations to gain understanding of molecular mechanism of self-assembly of nanostructures formed by diblock copolymer micelles interconnected by means of metal-ligand complexation. These systems exhibit interesting chemical and mechanical stimuli-responsive behavior and possess two levels of self-assembly: 1) self-assembly of diblock copolymers into micelles and 2) reversible inter-micelle bridging by coordination bonding between metal ions and ligands attached to the corona of nanoparticles, which is responsible for the network viscoelastic properties. Using MC simulations we investigate the effect of metal-ligand complexation on diblock-copolymer micelle formation and vice versa. We analyze the extent of intra- and inter-micelle loops and bridges formed by metal-ligand complexation in relation to the degree of crosslinking and elastic properties of the network. The effect of polymer concentration, hydrophilic block length, metal to oligomer ratio and type of complexation (2:1 or 3:1) on equilibrium properties of reversible networks will be discussed.

  17. Synthesis of amphiphilic diblock copolymer for surface modification of Ethylene-Norbornene Copolymers

    NASA Astrophysics Data System (ADS)

    Levinsen, Simon; Svendsen, Winnie Edith; Horsewell, Andy; Almdal, Kristoffer

    2014-03-01

    The aim of this work is to produce polymer modifiers in order to develop hydrophilic polymeric surfaces for use in microfluidics. The use of hydrophilic polymers in microfluidics will have many advantages e.g. preventing protein absorbance. Here we present an amphiphilic diblock copolymer consisting of a bulk material compatible block and a hydrophilic block. To utilize the possibility of incorporating diblock copolymers into ethylene-norbornene copolymers, we have in this work developed a model poly(ethylene-1-butene) polymer compatible with the commercial available ethylene-norbornene copolymer TOPAS. Through matching of the radius of gyration for the model polymer and TOPAS the miscibility was achieved. The poly(ethylene-1-butene) polymer was synthesized from a hydrogenated anionic polymerized polybutadiene polymer. As hydrophilic block poly(ethylene oxide) was subsequently added also with anionic polymerization. Recent miscibility results between the model polymer and TOPAS will be presented, as well ongoing efforts to study the hydrophilic surface.

  18. Molecular Interaction Control in Diblock Copolymer Blends and Multiblock Copolymers with Opposite Phase Behaviors

    NASA Astrophysics Data System (ADS)

    Cho, Junhan

    2014-03-01

    Here we show how to control molecular interactions via mixing AB and AC diblock copolymers, where one copolymer exhibits upper order-disorder transition and the other does lower disorder-order transition. Linear ABC triblock copolymers possessing both barotropic and baroplastic pairs are also taken into account. A recently developed random-phase approximation (RPA) theory and the self-consistent field theory (SCFT) for general compressible mixtures are used to analyze stability criteria and morphologies for the given systems. It is demonstrated that the copolymer systems can yield a variety of phase behaviors in their temperature and pressure dependence upon proper mixing conditions and compositions, which is caused by the delicate force fields generated in the systems. We acknowledge the financial support from National Research Foundation of Korea and Center for Photofunctional Energy Materials.

  19. Water-soluble copolymers. IV. Random copolymers of acrylamide with sulfonated comonomers

    SciTech Connect

    McCormick, C.L.; Chen, G.S.

    1982-03-01

    Random copolymers of acrylamide with sodium-2-sulfoethyl methacrylate and with sodium-2-acrylamido-2-methylpropane sulfonate were synthesized in aqueous solutions utilizing persulfate initiators. Copolymer compositions were determined by elemental analysis and by infrared spectroscopic methods. Monomer reactivity ratios were calculated using Fineman-Ross, Kelen-Tuedos, and/or Mayo-Lewis techniques at appropriate conversions. The copolymer microstructure, including mean sequence length distributions, was calculated from reactivity ratios. Membrane osmometry and viscometry measurements were utilized to estimate molecular weight and size. The large dimensions of these polyelectrolytes in aqueous solutions, as well as their inherent hydrogen bonding capacity and pseudoplasticity, make these copolymers excellent candidates for application as mobility control agents in enhanced oil recovery.

  20. Mixing thermodynamics of block-random copolymers

    NASA Astrophysics Data System (ADS)

    Beckingham, Bryan Scott

    Random copolymerization of A and B monomers represents a versatile method to tune interaction strengths between polymers, as ArB random copolymers will exhibit a smaller effective Flory interaction parameter chi; (or interaction energy density X) upon mixing with A or B homopolymers than upon mixing A and B homopolymers with each other, and the ArB composition can be tuned continuously. Thus, the incorporation of a random copolymer block into the classical block copolymer architecture to yield "block-random" copolymers introduces an additional tuning mechanism for the control of structure-property relationships, as the interblock interactions and physical properties can be tuned continuously through the random block's composition. However, typical living or controlled polymerizations produce compositional gradients along the "random" block, which can in turn influence the phase behavior. This dissertation demonstrates a method by which narrow-distribution copolymers of styrene and isoprene of any desired composition, with no measurable down-chain gradient, are synthesized. This synthetic method is then utilized to incorporate random copolymers of styrene and isoprene as blocks into block-random copolymers in order to examine the resulting interblock mixing thermodynamics. A series of well-defined near-symmetric block and block-random copolymers (S-I, Bd-S, I-SrI, S-SrI and Bd-S rI diblocks, where S is polystyrene, I is polyisoprene and Bd is polybutadiene), with varying molecular weight and random-block composition are synthesized and the mixing thermodynamics---via comparison of their interaction energy densities, X---of their hydrogenated derivatives is examined through measurement of the order-disorder transition (ODT) temperature. Hydrogenated derivatives of I-SrI and S-SrI block-random copolymers, both wherein the styrene aromaticity is retained and derivatives wherein the styrene units are saturated to vinylcyclohexane (VCH), are found to hew closely to the

  1. Shape Control in Engineering of Polymeric Nanoparticles for Therapeutic Delivery

    PubMed Central

    Williford, John-Michael; Santos, Jose Luis; Shyam, Rishab; Mao, Hai-Quan

    2015-01-01

    Nanoparticle-mediated delivery of therapeutics holds great potential for the diagnosis and treatment of a wide range of diseases. Significant advances have been made in the design of new polymeric nanoparticle carriers through modulation of their physical and chemical structures and biophysical properties. Nanoparticle shape has been increasingly proposed as an important attribute dictating their transport properties in biological milieu. In this review, we highlight three major methods for preparing polymeric nanoparticles that allow for exquisite control of particle shape. Special attention is given to various approaches to controlling nanoparticle shape by tuning copolymer structural parameters and assembly conditions. This review also provides comparisons of these methods in terms of their unique capabilities, materials choices, and specific delivery cargos, and summarizes the biological effects of nanoparticle shape on transport properties at the tissue and cellular levels. PMID:26146550

  2. Block copolymer nanolithography for the fabrication of patterned media.

    SciTech Connect

    Warke, Vishal V; Bakker, Martin G; Hong, Kunlun; Mays, Jimmy; Britt, Phillip F; Li, Xuefa; Wang, Jin

    2008-01-01

    Abstract Bit patterned perpendicular media has the potential to increase the density of magnetic recording beyond what can be achieved by granular media. Self assembling diblock copolymers are of interest as templates for patterned media, as they potentially provide a low cost fabrication route. A method to fabricate the desired pattern using cylinder forming diblock copolymers of (PS-b-PMMA) as template is reported. Upon phase separation hexagonally packed cylinders of the minority phase (PMMA) surrounded by the continuous majority phase (PS) are obtained. The processing sequence began with spin coating the block copolymer on a suitable substrate, followed by annealing the block copolymer thin film in vacuum to orient it perpendicular to the substrate. Block copolymer templates were obtained by glacial acetic acid treatment which opened the pores in the block copolymer thin film. Ni was electrodeposited in the block copolymer templates and this pattern was then transferred onto the underlying substrate by ion milling

  3. Nanostructured Colloidal Particles by Confined Self-Assembly of Block Copolymers in Evaporative Droplets

    NASA Astrophysics Data System (ADS)

    Kim, Minsoo; Yi, Gi-Ra

    2015-06-01

    Block copolymers (BCPs) can create various morphology by self-assembly in bulk or film. Recently, using BCPs in confined geometries such as thin film (one-dimension), cylindrical template (two-dimension), or emulsion droplet (three-dimension), nanostructured BCP particles have been prepared, in which unique nanostructures of the BCP are formed via solvent annealing process and can be controlled depending on molecular weight ratio and interaction parameter of the BCPs, and droplet size. Moreover, by tuning interfacial property of the BCP particles, anisotropic particles with unique nanostructures have been prepared. Furthermore, for practical application such as drug delivery system, sensor, self-healing, metamaterial, and optoelectronic device, functional nanoparticles can be incorporated inside BCP particles. In this article, we summarize recent progress on the production of structured BCP particles and composite particles with metallic nanoparticles.

  4. Bragg Reflectors Based on Block Copolymer/Polyhedral Oligomeric Silsesquioxanes (POSS) and TiO2 Hybrid Nanocomposites

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Colella, Nicholas; Watkins, James

    2014-03-01

    Maleamic acid functionalized polyhedral oligomeric silsesquioxanes (POSS) can interact with the poly (ethylene oxide) (PEO) block in Pluronics F108 block copolymer via hydrogen bonding to form well-ordered block copolymer nanocomposites. In this study, the block copolymer composites are spin coated into thin films and maleamic acid groups are thermal crosslinked to stabilize the nanocomposite structure. High temperature calcination of the stabilized nanocomposite yields a robust mesoporous silica thin film. By adjusting the loading of POSS into the block copolymer prior to calcination, the refractive index (RI) of mesoporous silica films can be tuned between 1.13 and 1.18. We show these low RI films can be sequentially layered with hybrid TiO2 nanocomposite films that exhibit a RI of approximately 2.0 to yield efficient Bragg reflectors. The TiO2 films are prepared by the calcinations of polymer/anatase TiO2 nanoparticle composites with NP loadings as high as 90wt%. Due to the porosity existing in each layer, the wavelength of the reflected light is sensitive to the adsorption of solvent vapors such as toluene, isopropanol, and tetrahydrofuran, or analytes, which suggest applications in sensors. Acknowledge The Center for Hierarchical Manufacturing.

  5. Particle formation and aggregation-collapse behavior of poly(N-isopropylacrylamide) and poly(ethylene glycol) block copolymers in the presence of cross-linking agent.

    PubMed

    Zhu, Peng-Wei

    2004-05-01

    The effect of feed molar ratio of N-isopropylacrylamide (NIPAM) to poly(ethylene oxide) (PEO) on the particle formation of poly(N-isopropylacrylamide) (PNIPAM) and PEO block copolymers (PNIPAM-b-PEO) and their aggregation-collapse behavior have been studied in aqueous solutions. It is found that in the presence of cross-linking agent N,N'-methylenebisacryla-mide (BIS), different morphologies of PNIPAM-b-PEO copolymers can be obtained, including a grafting-like structure, a hemispherical core-shell structure and a well-defined core-shell nanoparticle, as the feed molar amount of NIPAM in the copolymerization is increased. The increase in temperature causes the self-aggregation of grafting-like copolymers and hemispherical particles due to the hydrophobic interaction between locally unshielded PNIPAM blocks prior to the conformational transition of PNIPAM. When the feed molar ratio of NIPAM to PEO exceeds a certain value, a well-defined core-shell nanoparticle can be produced during the copolymerization. At low concentrations, PNIPAM cores of single core-shell nanoparticles can undergo the conformational transition without aggregation. The increase in the concentration of the well-defined core-shell nanoparticles, however, results in a week aggregation at temperatures lower than the theta-temperature of pure PNIPAM due to the association of methyl groups at the periphery of PEO shells. PMID:15386964

  6. Timed-release polymer nanoparticles.

    PubMed

    Tran, Nguyen T D; Truong, Nghia P; Gu, Wenyi; Jia, Zhongfan; Cooper, Matthew A; Monteiro, Michael J

    2013-02-11

    Triggered-release of encapsulated therapeutics from nanoparticles without remote or environmental triggers was demonstrated in this work. Disassembly of the polymer nanoparticles to unimers at precise times allowed the controlled release of oligo DNA. The polymers used in this study consisted of a hydrophilic block for stabilization and second thermoresponsive block for self-assembly and disassembly. At temperatures below the second block's LCST (i.e., below 37 °C for in vitro assays), the diblock copolymer was fully water-soluble, and when heated to 37 °C, the polymer self-assembled into a narrow size distribution of nanoparticles with an average diameter of approximately 25 nm. The thermoresponsive nature of the second block could be manipulated in situ by the self-catalyzed degradation of cationic 2-(dimethylamino)ethyl acrylate (DMAEA) units to negatively charged acrylic acid groups and when the amount of acid groups was sufficiently high to increase the LCST of the second block above 37 °C. The disassembly of the nanoparticles could be controlled from 10 to 70 h. The use of these nanoparticles as a combined therapy, in which one or more agents can be released in a predetermined way, has the potential to improve the personal point of care treatment of patients. PMID:23298322

  7. New Nanoporous Carbon Materials from Block Copolymer Precursors for Supercapacitor Applications

    NASA Astrophysics Data System (ADS)

    Kim, Eun Kyung

    This dissertation explores the physicochemical characterization of nanoporous carbon materials obtained by the pyrolysis of PAN-b-PBA block copolymers and their application to supercapacitor electrodes. The introductory chapter provides an overview of porous carbon materials and their application as supercapacitor electrodes. Chapter 2 demonstrated that block copolymers containing a source of carbon (PAN) and a sacrificial block (PBA) can be converted into porous carbons with nanostructure faithfully molded by the nanostructure of the block copolymer. An unusually high capacitance per unit area (>30 microF/cm 2) of the supercapacitors fabricated from such prepared carbon was attributed to the pseudocapacitance, which was a result of the high content of nitrogen atoms originating from the PAN precursor. In Chapter 3, the concomitant decrease of capacitance per unit area and of nitrogen content with the increase of pyrolysis temperature/time further confirmed the role of nitrogen atoms as a source of pseudocapacitance. In Chapter 4, it was proven that the pore size distribution of nanoporous carbon is directly determined by the length of PBA block in block copolymer, which also affects the supercapacitor performance. In Chapter 5, the nanoporous carbon underwent CO2, and KOH activation treatment. Although the total surface area increased two-fold and five-fold, respectively, there was little difference in the mass-normalized capacitance values, which was explained by the reduced nitrogen content after the activation treatment. In Chapter 6, three kinds of silica nanoparticle-templated nanoporous carbon showed capacitance values of 40 ˜ 100 F/g in three aqueous electrolytes. In Chapter 7, various resistance-capacitance circuit models were built and simulated electrochemical data.

  8. Copolymer sealant compositions and method for making

    NASA Technical Reports Server (NTRS)

    Singh, Navjot (Inventor); Leman, John Thomas (Inventor); Whitney, John M. (Inventor); Krabbenhoft, Herman Otto (Inventor)

    2002-01-01

    Condensation curable poly(fluoroorgano)siloxane-poly(silarylene)siloxane block copolymer compositions having a glass transition temperature not exceeding about -54.degree. C. and excellent solvent resistance have been found useful as sealants. Polyalkoxysilylorgano compounds, such as 1,4-bis[trimethoxysilyl(ethyl)]benzene have been found to be effective as cross-linkers.

  9. Copolymer sealant compositions and method for making

    NASA Technical Reports Server (NTRS)

    Singh, Navjot (Inventor); Leman, John Thomas (Inventor); Whitney, John M. (Inventor); Krabbenhoft, Herman Otto (Inventor)

    2004-01-01

    Condensation curable poly(fluoroorgano)siloxane-poly(silarylene)siloxane block copolymer compositions having a glass transition temperature not exceeding about -54.degree. C. and excellent solvent resistance have been found useful as sealants. Polyalkoxysilylorgano compounds, such as 1,4-bis[trimethoxysilyl(ethyl)]benzene have been found to be effective as cross-linkers.

  10. Copolymer sealant compositions and method for making

    NASA Technical Reports Server (NTRS)

    Singh, Navjot (Inventor); Leman, John Thomas (Inventor); Whitney, John M. (Inventor); Krabbenhoft, Herman Otto (Inventor)

    2003-01-01

    Condensation curable poly(fluoroorgano)siloxane-poly(silarylene)siloxane block copolymer compositions having a glass transition temperature not exceeding about -54.degree. C. and excellent solvent resistance have been found useful as sealants. Polyalkoxysilylorgano compounds, such as 1,4-bis[trimethoxysilyl(ethyl)]benzene have been found to be effective as cross-linkers.

  11. 21 CFR 173.65 - Divinylbenzene copolymer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Divinylbenzene copolymer. 173.65 Section 173.65 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Polymer Substances and Polymer Adjuvants...

  12. 21 CFR 173.65 - Divinylbenzene copolymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Divinylbenzene copolymer. 173.65 Section 173.65 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Polymer Substances and Polymer Adjuvants...

  13. 21 CFR 173.65 - Divinylbenzene copolymer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Divinylbenzene copolymer. 173.65 Section 173.65 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Polymer Substances and Polymer Adjuvants...

  14. Fungal biodegradation of lignopolystyrene graft copolymers.

    PubMed Central

    Milstein, O; Gersonde, R; Huttermann, A; Chen, M J; Meister, J J

    1992-01-01

    White rot basidiomycetes were able to biodegrade styrene (1-phenylethene) graft copolymers of lignin containing different proportions of lignin and polystyrene [poly(1-phenylethylene)]. The biodegradation tests were run on lignin-styrene copolymerization products which contained 10.3, 32.2, and 50.4% (wt/wt) lignin. The polymer samples were incubated with the white rot fungi Pleurotus ostreatus, Phanerochaete chrysosporium, and Trametes versicolor and the brown rot fungus Gloeophyllum trabeum. White rot fungi degraded the plastic samples at a rate which increased with increasing lignin content in the copolymer sample. Both polystyrene and lignin components of the copolymer were readily degraded. Polystyrene pellets were not degradable in these tests. Degradation was verified for both incubated and control samples by weight loss, quantitative UV spectrophotometric analysis of both lignin and styrene residues, scanning electron microscopy of the plastic surface, and the presence of enzymes active in degradation during incubation. Brown rot fungus did not affect any of the plastics. White rot fungi produced and secreted oxidative enzymes associated with lignin degradation in liquid media during incubation with lignin-polystyrene copolymer. Images PMID:1444360

  15. 21 CFR 177.2470 - Polyoxymethylene copolymer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ....2470 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use Only as... copolymer identified in this section may be safely used as an article or component of articles intended...

  16. 21 CFR 177.2470 - Polyoxymethylene copolymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ....2470 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use Only as... copolymer identified in this section may be safely used as an article or component of articles intended...

  17. Block copolymers for enhanced oil recovery

    SciTech Connect

    Wu, M.M.; Ball, L.E.

    1987-05-19

    A water soluble block copolymer is described comprising two or more water soluble polymer blocks, wherein the water soluble polymer blocks comprise polymerized monomers. The monomers are selected from the group consisting of acrylamide, methacrylamide, vinyl methyl ether, acrylic and methacrylic acid and their water soluble salts and N-substituted acrylamides.

  18. Molecular transfer printing using block copolymers.

    PubMed

    Ji, Shengxiang; Liu, Chi-Chun; Liu, Guoliang; Nealey, Paul F

    2010-02-23

    Soft lithographic techniques augment or enhance the capabilities of traditional patterning processes and expand the diversity of materials that can be patterned. Realization of robust parallel techniques for creating chemical patterns at the nanoscale has been challenging. Here we present a method for creating and replicating chemical patterns that uses functionalized homopolymer inks that are preferentially segregated into the nanodomains of phase-separated diblock copolymer films. The inks are transferred by reaction to substrates that are brought into contact with block copolymer films, creating chemical patterns on the substrate that mirror the domain structure present at the film surface with high fidelity and resolution. In addition to printing from self-assembled domain structures, we can also direct the assembly of the block copolymer films from which transfer occurs using lithographically defined masters so as to replicate and transfer patterns of inks with controlled and well-defined geometries. The transferred patterns may be at higher resolution than the lithographically defined master, and the process can be repeated to create multiple copies of identical replicas. Transfer of one ink from one block of the copolymer is also possible, and filling the interspatial regions of the pattern with a second ink provides a pathway toward creating patterns with diverse chemical functionalities. PMID:20041629

  19. Amphiphilic block copolymer nanocontainers as bioreactors

    NASA Astrophysics Data System (ADS)

    Nardin, C.; Widmer, J.; Winterhalter, M.; Meier, W.

    2001-04-01

    Self-assembly of an amphiphilic triblock copolymer carrying polymerizable end-groups is used to prepare nanometer-sized vesicular structures in aqueous solution. The triblock copolymer shells of the vesicles can be regarded as a mimetic of biological membranes although they are 2 to 3 times thicker than a conventional lipid bilayer. Nevertheless, they can serve as a matrix for membrane-spanning proteins. Surprisingly, the proteins remain functional despite the extreme thickness of the membranes and that even after polymerization of the reactive triblock copolymers. This opens a new field to create mechanically stable protein/polymer hybrid membranes. As a representative example we functionalize (polymerized) triblock copolymer vesicles by reconstituting a channel-forming protein from the outer cell wall of Gram-negative bacteria. The protein used (OmpF) acts as a size-selective filter, which allows only for passage of molecules with a molecular weight below 400 g mol^{-1}. Therefore substrates may still have access to enzymes encapsulated in such protein/polymer hybrid nanocontainers. We demonstrate this using the enzyme β -lactamase which is able to hydrolyze the antibiotic ampicillin. In addition, a transmembrane voltage above a given threshold causes a reversible gating transition of OmpF. This can be used to reversibly activate or deactivate the resulting nanoreactors.

  20. Oral Delivery of DMAB-Modified Docetaxel-Loaded PLGA-TPGS Nanoparticles for Cancer Chemotherapy

    NASA Astrophysics Data System (ADS)

    Chen, Hongbo; Zheng, Yi; Tian, Ge; Tian, Yan; Zeng, Xiaowei; Liu, Gan; Liu, Kexin; Li, Lei; Li, Zhen; Mei, Lin; Huang, Laiqiang

    2011-12-01

    Three types of nanoparticle formulation from biodegradable PLGA-TPGS random copolymer were developed in this research for oral administration of anticancer drugs, which include DMAB-modified PLGA nanoparticles, unmodified PLGA-TPGS nanoparticles and DMAB-modified PLGA-TPGS nanoparticles. Firstly, the PLGA-TPGS random copolymer was synthesized and characterized. DMAB was used to increase retention time at the cell surface, thus increasing the chances of particle uptake and improving oral drug bioavailability. Nanoparticles were found to be of spherical shape with an average particle diameter of around 250 nm. The surface charge of PLGA-TPGS nanoparticles was changed to positive after DMAB modification. The results also showed that the DMAB-modified PLGA-TPGS nanoparticles have significantly higher level of the cellular uptake than that of DMAB-modified PLGA nanoparticles and unmodified PLGA-TPGS nanoparticles. In vitro, cytotoxicity experiment showed advantages of the DMAB-modified PLGA-TPGS nanoparticle formulation over commercial Taxotere® in terms of cytotoxicity against MCF-7 cells. In conclusion, oral chemotherapy by DMAB-modified PLGA-TPGS nanoparticle formulation is an attractive and promising treatment option for patients.

  1. Synthesis of polysaccharide-block-polypeptide copolymer for potential co-delivery of drug and plasmid DNA.

    PubMed

    Li, Qianqian; Liu, Wenya; Dai, Jian; Zhang, Chao

    2015-06-01

    A pH-sensitive, biodegradable, and biocompatible polysaccharide-block-polypeptide Copolymer derivative {Ac-Dex-b-PAsp(DET)} is synthetized from acetal-modified dextran (Ac-Dex) and diethylenetriamine (DET) grafted poly(L-aspartic acid) {PAsp(DET)} by using click and aminolysis reaction. The copolymer can self-assemble into cationic nanopaticles for potential co-delivery of plasmid DNA (pEGFP-N3) and anticancer drug (doxorubicin, DOX), by using water/oil/water (w/o/w) emulsion method. Gel retardation assay reveals that pDNA can be effectively complexed into cationic nanoparticles at N/P ratio = 12. In vitro drug release behavior of DOX-NPs and DOX/pDNA-NPs is achieved by using fluorescence spectra and UV-Vis spectra and confocal laser scanning microscopy (CLSM). And, pEGFP-N3-NPs at N/P ratio = 42 presents the considerable potential in cell transfection. Cell viability assay shows that nanoparticles exhibit low cell cytotoxicity. These results suggest that the copolymer has excellent performance and potential for the co-delivery of gene and drugs. PMID:25761094

  2. Micellization of pH-responsive Amphiphilic Diblock Copolymers in Aqueous Media and the Formation of Metal Nanocrystals

    NASA Astrophysics Data System (ADS)

    Anastasiadis, Spiros H.

    2005-03-01

    External-stimuli responsive block copolymers, usually known as double-hydrophilic copolymers, respond to changes in their environment such as pH, temperature and salt concentration and undergo micellization in aqueous media. Micellization induced by controlling the solution pH is advantageous for certain applications in particular when fully hydrophobic cores are required. A category of such systems comprise a pH-sensitive (weak) basic or acidic block that forms the micelle core surrounded by a corona formed by a neutral hydrophilic block. In this work we investigate the micellization behavior and the metal-nanoparticle formation in poly(2-(diethylamino)ethyl methacrylate)-block-poly(hexa(ethylene glycol) methacrylate), PDEAEMA-b-PHEGMA, amphiphilic block copolymers in aqueous media. The hydrophobic PDEAEMA block is pH-sensitive: at low pH it can be protonated and it becomes partially or completely hydrophilic, leading to molecular solubility, whereas at higher pH micelles are formed; the behavior is studied by dynamic light scattering, 1H-NMR and atomic force microscopy. The micelles consist of a PDEAEMA core and a PHEGMA corona, where the core can dissolve metal compounds due to coordination. In all these micellar nanoreactors, metal nanoparticles nucleate and grow upon reduction with sizes in the range of a few nanometers as observed by transmission electron microscopy whereas X-ray diffraction verifies their nanocrystalline structure. These particles exhibit significantly enhanced catalytic properties for hydrogenation and oxidation reactions.

  3. Tartaric Acid-Assisted Self-Assembly of Hybrid Block Copolymer Composites

    NASA Astrophysics Data System (ADS)

    Yao, Li; Lin, Ying; Watkins, James

    2014-03-01

    Enantiopure tartaric acid was used as an additive to increase the segregation strength of poly(ethylene oxide-block-tert-butyl acrylate) (PEO-b-PtBA) copolymers through strong, selective interactions with one of the polymer chain segments. Addition of tartaric acid to PEO-b-PtBA exhibiting cylindrical morphologies resulted in the formation of helical superstructures as observed by transmission electron microscopy. It was also found that this small acid additive can also enable phase-selective ultra-high loading of nanoparticles (NPs) into target domains of the block copolymer composites. The loading of tartaric acid can increase enthalpically favorable interactions between the nanoparticle ligands and the host domain and mitigate entropic penalties associated with NP incorporation into the target domain. A metal content of over 40 weight percent by mass of the resulting well ordered composites was achieved as measured by thermal gravimetric analysis in PEO-b-PtBA/tartaric acid/4-hydroxythiophenol functionalized Au NP hybrid system. Funding from Center for Hierarchical Manufacturing (CHM); Facility support from Materials Research Science and Engineering Center at UMass Amherst.

  4. Directed Self-Assembly of Block Copolymers in Thin Films on Polymer Nano-Stripes

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Eun; Kang, Ho-Jong; Lee, Dong Hyun; Nano Functional Materials Lab. Team

    In this study, we report directed self-assembly (DSA) of block copolymers in thin films on nano-stripes of polymers. Unique nano-stripes of poly(tetrafluoro ethylene) (PTFE) having ~20 nm of amplitude and ~200 nm of pitch were simply generated by physically rubbing a PTFE bar on various substrates like Si wafers, glass, and polyimide due to its low friction coefficient and high wear rate. The resulting nano-stripes were extremely oriented along the rubbing direction. Then, various asymmetric polystyrene-block-poly(2-vinylpyridine) copolymers (PS- b-P2VP) were directly self-assembled on the nano-stripes of PTFE by solvent-annealing in vapor of tetrahydrofuran (THF). As a result, PS- b-P2VP exhibited extremely ordered P2VP cylinders oriented normal to the surface in large area on the underlying nano-stripes of PTFE. In addition, as utilizing the BCPs as templates, hexagonal arrays of metal nanoparticles were generated in large area for further application. BCP thin films and arrays of metal nanoparticles were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM).

  5. Thermal Conductivity of Ethylene Vinyl Acetate Copolymer/Nanofiller Blends

    NASA Technical Reports Server (NTRS)

    Ghose, S.; Watson, K. A.; Working, D. C.; Connell, J. W.; Smith, J. G., Jr.; Lin, Y.; Sun, Y. P.

    2007-01-01

    To reduce weight and increase the mobility, comfort, and performance of future spacesuits, flexible, thermally conductive fabrics and plastic tubes are needed for the Liquid Cooling and Ventilation Garment. Such improvements would allow astronauts to operate more efficiently and safely for extended extravehicular activities. As an approach to raise the thermal conductivity (TC) of an ethylene vinyl acetate copolymer (Elvax 260), it was compounded with three types of carbon based nanofillers: multi-walled carbon nanotubes (MWCNTs), vapor grown carbon nanofibers (CNFs), and expanded graphite (EG). In addition, other nanofillers including metallized CNFs, nickel nanostrands, boron nitride, and powdered aluminum were also compounded with Elvax 260 in the melt at various loading levels. In an attempt to improve compatibility between Elvax 260 and the nanofillers, MWCNTs and EG were modified by surface coating and through noncovalent and covalent attachment of organic molecules containing alkyl groups. Ribbons of the nanocomposites were extruded to form samples in which the nanofillers were aligned in the direction of flow. Samples were also fabricated by compression molding to yield nanocomposites in which the nanofillers were randomly oriented. Mechanical properties of the aligned samples were determined by tensile testing while the degree of dispersion and alignment of nanoparticles were investigated using high-resolution scanning electron microscopy. TC measurements were performed using a laser flash (Nanoflash ) technique. TC of the samples was measured in the direction of, and perpendicular to, the alignment direction. Additionally, tubing was also extruded from select nanocomposite compositions and the TC and mechanical flexibility measured.

  6. Two-Dimensional Confinement of Nanorods in Block Copolymer Domains

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Deshmukh, Ranjan; Composto, Russell

    2008-03-01

    To control their unique electrical and optical properties, one-dimensional metallic/semiconductor nanoparticles need to be aligned and assembled within a host material. In our research, we investigated the assembly of gold nanorods (NRs) in films of a symmetric diblock copolymer, poly(styrene-b-methyl methacrylate), PS-b-PMMA (211kg/mol). The NR length and diameter was 42nm and 13nm, respectively. The NRs were grafted with a short PEG-brush (5kg/mol). During solvent annealing, the NRs become oriented as the PS-b-PMMA chains assemble into a parallel lamellar morphology. The NRs are selectively sequestered and confined in the PMMA domains, which are narrower than the NR length, due to the favorable interaction between the PEG brush and PMMA block. This confinement orients 71% of NRs within ± 5^o of the lamella plane. This route to produce alternating layers containing conducting NRs separated by dielectric domains has the potential for fabricating self-assembled nanodevices. The thermal stability of the NRs in PS-b-PMMA and homo PMMA films will also be discussed.

  7. Direct Immersion Annealing of Block Copolymer Thin Films

    NASA Astrophysics Data System (ADS)

    Karim, Alamgir

    We demonstrate ordering of thin block copolymer (BCP) films via direct immersion annealing (DIA) at enhanced rate leading to stable morphologies. The BCP films are immersed in carefully selected mixtures of good and marginal solvents that can impart enhanced polymer mobility, while inhibiting film dissolution. DIA is compatible with roll-to-roll assembly manufacturing and has distinct advantages over conventional thermal annealing and batch processing solvent-vapor annealing methods. We identify three solvent composition-dependent BCP film ordering regimes in DIA for the weakly interacting polystyrene -poly(methyl methacrylate) (PS -PMMA) system: rapid short range order, optimal long-range order, and a film instability regime. Kinetic studies in the ``optimal long-range order'' processing regime as a function of temperature indicate a significant reduction of activation energy for BCP grain growth compared to oven annealing at conventional temperatures. An attractive feature of DIA is its robustness to ordering other BCP (e.g. PS-P2VP) and PS-PMMA systems exhibiting spherical, lamellar and cylindrical ordering. Inclusion of nanoparticles in these films at high concentrations and fast ordering kinetics study with neutron reflectivity and SANS will be discussed. This is (late) Contributed Talk Abstract for Dillon Medal Symposium at DPOLY - discussed with DPOLY Chair Dvora Perahia.

  8. Hybrid nanoparticle architecture for cellular uptake and bioimaging: direct crystallization of a polymer immobilized with magnetic nanoparticles on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Depan, D.; Misra, R. D. K.

    2012-09-01

    We describe here the success of an innovative approach of direct immobilization of magnetic nanoparticles (MNPs) onto carbon nanotubes (CNTs). The approach involved functionalization of magnetic nanoparticles and consequent covalent linkage to a copolymer (PE-b-PEG). Next, the immobilized magnetic nanoparticles on the copolymer were directly crystallized on the long axis of CNTs, where the interfacial adhesion comes from electrostatic and van der Waals interaction. The intracellular trafficking of a hybrid nanoparticle system [(PE-b-PEG)-MNP-CNT-FITC] in HeLa cells was monitored using a fluorescent marker, FITC, conjugated to the nanoparticle system. The distribution of the nanoparticle system inside cells was studied by fluorescence microscopy in a time and dose dependent manner, and it was observed that the nanoparticles are located in the cytoplasm and no apparent cell death was observed at the concentration studied. Also, the effect of an externally applied magnetic field on actin cytoskeleton, cell morphology and intracellular uptake of iron was studied. The approach described here is promising for simultaneous imaging and monitoring intracellular uptake.

  9. Structure property relations in glassy-semicrystalline block copolymers

    NASA Astrophysics Data System (ADS)

    Khanna, Vikram

    The ability of block copolymers to segregate into nanoscale morphologies makes them a versatile class of engineering materials. This work investigates the relation between the block copolymer structure and its mechanical properties, film dynamics and diffusion kinetics. The first part investigates the influence of structure on the mechanical properties of poly(cyclohexylethylene)-poly(ethylene) (PCHE-PE) block copolymer films. For lamellar block copolymers the mechanical properties depend significantly on the chain architecture (diblock, triblock and pentablock). Diblock copolymer films show complete failure at small strains and pentablock copolymer films show the toughest, response. Moreover, the orientation of the cylinders in a cylinder forming pentablock copolymer affects the toughness of the block copolymer films. In the second part, the effect of surface energy and chain architecture on the orientation of microdomains in the same block copolymer films is investigated. Cylindrical and lamellar triblock copolymers with a PE midblock orient their microdomains normal to the surface. However, a lamellar diblock copolymer prefers a parallel orientation of the sheets with an E surface. Moreover, a cylindrical triblock copolymer with a reduced surface energy poly(ethylene-butylene) midblock orders with the cylinder domains oriented parallel to the surface. Self-consistent field theory calculations suggest that the entropic cost of forming a wetting layer comprised entirely of looping blocks for the triblock architecture, a constraint absent in diblock copolymers, stabilizes the perpendicular orientation. Thus in triblock copolymers, parallel orientations are only stabilized when the surface energy of the midblock is small enough to compensate for this conformational penalty. Finally, a study of the diffusion kinetics of cylinder forming poly(styrene)-poly(ethylene) triblock (SES) and pentablock (SESES) copolymers suggests that for similar molecular weights SESES

  10. Phase behavior of model ABC triblock copolymers

    NASA Astrophysics Data System (ADS)

    Chatterjee, Joon

    The phase behavior of poly(isoprene-b-styrene- b-ethylene oxide) (ISO), a model ABC triblock copolymer has been studied. This class of materials exhibit self-assembly, forming a large array of ordered morphologies at length scales of 5-100 nm. The formation of stable three-dimensionally continuous network morphologies is of special interest in this study. Since these nanostructures considerably impact the material properties, fundamental knowledge for designing ABC systems have high technological importance for realizing applications in the areas of nanofabrication, nanoporous media, separation membranes, drug delivery and high surface area catalysts. A comprehensive framework was developed to describe the phase behavior of the ISO triblock copolymers at weak to intermediate segregation strengths spanning a wide range of composition. Phases were characterized through a combination of characterization techniques, including small angle x-ray scattering, dynamic mechanical spectroscopy, transmission electron microscopy, and birefringence measurements. Combined with previous investigations on ISO, six different stable ordered state symmetries have been identified: lamellae (LAM), Fddd orthorhombic network (O70), double gyroid (Q230), alternating gyroid (Q214), hexagonal (HEX), and body-centered cubic (BCC). The phase map was found to be somewhat asymmetric around the fI = fO isopleth. This work provides a guide for theoretical studies and gives insight into the intricate effects of various parameters on the self-assembly of ABC triblock copolymers. Experimental SAXS data evaluated with a simple scattering intensity model show that local mixing varies continuously across the phase map between states of two- and three-domain segregation. Strategies of blending homopolymers with ISO triblock copolymer were employed for studying the swelling properties of a lamellar state. Results demonstrate that lamellar domains swell or shrink depending upon the type of homopolymer that

  11. Fabrication, modeling and characterization of multi-crosslinked methacrylate copolymeric nanoparticles for oral drug delivery.

    PubMed

    Ngwuluka, Ndidi C; Pillay, Viness; Choonara, Yahya E; Modi, Girish; Naidoo, Dinesh; du Toit, Lisa C; Kumar, Pradeep; Ndesendo, Valence M K; Khan, Riaz A

    2011-01-01

    Nanotechnology remains the field to explore in the quest to enhance therapeutic efficacies of existing drugs. Fabrication of a methacrylate copolymer-lipid nanoparticulate (MCN) system was explored in this study for oral drug delivery of levodopa. The nanoparticles were fabricated employing multicrosslinking technology and characterized for particle size, zeta potential, morphology, structural modification, drug entrapment efficiency and in vitro drug release. Chemometric Computational (CC) modeling was conducted to deduce the mechanism of nanoparticle synthesis as well as to corroborate the experimental findings. The CC modeling deduced that the nanoparticles synthesis may have followed the mixed triangular formations or the mixed patterns. They were found to be hollow nanocapsules with a size ranging from 152 nm (methacrylate copolymer) to 321 nm (methacrylate copolymer blend) and a zeta potential range of 15.8-43.3 mV. The nanoparticles were directly compressible and it was found that the desired rate of drug release could be achieved by formulating the nanoparticles as a nanosuspension, and then directly compressing them into tablet matrices or incorporating the nanoparticles directly into polymer tablet matrices. However, sustained release of MCNs was achieved only when it was incorporated into a polymer matrix. The experimental results were well corroborated by the CC modeling. The developed technology may be potentially useful for the fabrication of multi-crosslinked polymer blend nanoparticles for oral drug delivery. PMID:22016653

  12. Fabrication, Modeling and Characterization of Multi-Crosslinked Methacrylate Copolymeric Nanoparticles for Oral Drug Delivery

    PubMed Central

    Ngwuluka, Ndidi C.; Pillay, Viness; Choonara, Yahya E.; Modi, Girish; Naidoo, Dinesh; du Toit, Lisa C.; Kumar, Pradeep; Ndesendo, Valence M.K.; Khan, Riaz A.

    2011-01-01

    Nanotechnology remains the field to explore in the quest to enhance therapeutic efficacies of existing drugs. Fabrication of a methacrylate copolymer-lipid nanoparticulate (MCN) system was explored in this study for oral drug delivery of levodopa. The nanoparticles were fabricated employing multicrosslinking technology and characterized for particle size, zeta potential, morphology, structural modification, drug entrapment efficiency and in vitro drug release. Chemometric Computational (CC) modeling was conducted to deduce the mechanism of nanoparticle synthesis as well as to corroborate the experimental findings. The CC modeling deduced that the nanoparticles synthesis may have followed the mixed triangular formations or the mixed patterns. They were found to be hollow nanocapsules with a size ranging from 152 nm (methacrylate copolymer) to 321 nm (methacrylate copolymer blend) and a zeta potential range of 15.8–43.3 mV. The nanoparticles were directly compressible and it was found that the desired rate of drug release could be achieved by formulating the nanoparticles as a nanosuspension, and then directly compressing them into tablet matrices or incorporating the nanoparticles directly into polymer tablet matrices. However, sustained release of MCNs was achieved only when it was incorporated into a polymer matrix. The experimental results were well corroborated by the CC modeling. The developed technology may be potentially useful for the fabrication of multi-crosslinked polymer blend nanoparticles for oral drug delivery. PMID:22016653

  13. 40 CFR 721.10523 - Perfluoroalkylethyl methacrylate copolymer with hydroxymethyl acrylamide, vinyl chloride and long...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... copolymer with hydroxymethyl acrylamide, vinyl chloride and long chain fatty alkyl acrylate (generic). 721... methacrylate copolymer with hydroxymethyl acrylamide, vinyl chloride and long chain fatty alkyl acrylate (PMN P... Substances § 721.10523 Perfluoroalkylethyl methacrylate copolymer with hydroxymethyl acrylamide,...

  14. 40 CFR 721.10523 - Perfluoroalkylethyl methacrylate copolymer with hydroxymethyl acrylamide, vinyl chloride and long...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... copolymer with hydroxymethyl acrylamide, vinyl chloride and long chain fatty alkyl acrylate (generic). 721... methacrylate copolymer with hydroxymethyl acrylamide, vinyl chloride and long chain fatty alkyl acrylate (PMN P... Substances § 721.10523 Perfluoroalkylethyl methacrylate copolymer with hydroxymethyl acrylamide,...

  15. 21 CFR 872.3500 - Polyvinylmethylether maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... Polyvinylmethylether maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium (NACMC) denture adhesive is a device composed of polyvinylmethylether maleic anhydride, acid copolymer, and... maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium (NACMC) denture...

  16. 21 CFR 872.3500 - Polyvinylmethylether maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... Polyvinylmethylether maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium (NACMC) denture adhesive is a device composed of polyvinylmethylether maleic anhydride, acid copolymer, and... maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium (NACMC) denture...

  17. 21 CFR 872.3500 - Polyvinylmethylether maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    .... Polyvinylmethylether maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium (NACMC) denture adhesive is a device composed of polyvinylmethylether maleic anhydride, acid copolymer, and... maleic anhydride (PVM-MA), acid copolymer, and carboxymethylcellulose sodium (NACMC) denture...

  18. Theory of Chirality Transfer in Block Copolymer Melts

    NASA Astrophysics Data System (ADS)

    Prasad, Ishan; Grason, Gregory

    Block copolymers assemble into a rich spectrum of ordered phases, with complexity driven by asymmetry in copolymer architecture. Despite decades of study, influence of intrinsic chirality on equilibrium mesophase assembly of block copolymers is not well understood and largely unexplored. Self-consistent field theory has been largely instrumental in prediction of physical properties of polymeric systems. Recently, a polar orientational self-consistent field (oSCF) theory was adopted to model chiral block copolymers having a thermodynamic preference for cholesteric ordering in chiral segments, and which confirmed the equilibrium stability of a helical cylinder morphology observed for chiral diblocks. Here, I describe a newly developed oSCF theory for chiral nematic copolymers, where segment orientations are characterized by quadrupolar interactions, and focus our study on intra-domain nematic ordering in flexible block copolymer assemblies, and in particular, mechanisms of transfer of segment chirality to mesochiral symmetries of self-assembled bicontinuous network morphologies.

  19. Synthesis and Characterization of New Poly(silole-fluorene) Copolymers.

    PubMed

    Lee, Yun-Ji; Park, Jeong Cheol; Yun, Hui-Jun; Park, Jong-Man; Kim, Yun-Hi

    2015-02-01

    New poly(silole-fluorene) copolymers were designed and synthesized. Copolymers were obtained by Suzuki coupling reaction with different ratio of fluorene and silole. The obtained copolymers were characterized by the spectroscopic methods such as FT-IR and 1H-NMR spectroscopies. The resulting copolymers were soluble in common organic solvents such as toluene, tetrahydrofurane, chloroform, chlorobenzene, etc. The obtained copolymers showed thermal stabilities, which were characterized by TGA and DSC. PLEDs with device configurations of ITO/PEDOT:PSS/Copolymer I~VI/LiF/AI. The best device performances, with maximum brightness of 231.5 cd/m2 at a current density (J) of 408.3 mA/cm2, and a maximum luminance efficiency of 0.115 cd/A, were achieved in the composition of fluorene and silole moiety (0.9:0.1). PMID:26353724

  20. Oxygen plasma resistant phosphine oxide containing imide/arylene copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.

    1993-01-01

    A series of oxygen plasma resistant imide/arylene ether copolymers were prepared by reacting anhydride-terminated poly(amide acids) and amine-terminated polyarylene ethers containing phosphine oxide units. Inherent viscosities for these copolymers ranged from 0.42 to 0.80 dL/g. After curing, the resulting copolymers had glass transition temperatures ranging from 224 C to 228 C. Solution cast films of the block copolymers were tough and flexible with tensile strength, tensile moduli, and elongation at break up to 16.1 ksi, 439 ksi, and 23 percent, respectively at 25 C and 9.1 ksi, 308 ksi and 97 percent, respectively at 150 C. The copolymers show a significant improvement in resistance to oxygen plasma when compared to the commercial polyimide Kapton. The imide/arylene ether copolymers containing phosphine oxide units are suitable as coatings, films, adhesives, and composite matrices.

  1. Phase Behavior of Neat Triblock Copolymers and Copolymer/Homopolymer Blends Near Network Phase Windows

    SciTech Connect

    M Tureau; L Rong; B Hsiao; T Epps

    2011-12-31

    The phase behavior of poly(isoprene-b-styrene-b-methyl methacrylate) (ISM) copolymers near the styrene-rich network phase window was examined through the use of neat triblock copolymers and copolymer/homopolymer blends. Both end-block and middle-block blending protocols were employed using poly(isoprene) (PI), poly(methyl methacrylate) (PMMA), and poly(styrene) (PS) homopolymers. Blended specimens exhibited phase transformations to well-ordered nanostructures (at homopolymer loadings up to 26 vol % of the total blend volume). Morphological consistency between neat and blended specimens was established at various locations in the ISM phase space. Copolymer/homopolymer blending permitted the refinement of lamellar, hexagonally packed cylinder, and disordered melt phase boundaries as well as the identification of double gyroid (Q{sup 230}), alternating gyroid (Q{sup 214}), and orthorhombic (O{sup 70}) network regimes. Additionally, the experimental phase diagram exhibited similar trends to those found in a theoretical ABC triblock copolymer phase diagram with symmetric interactions and statistical segments lengths generated by Tyler et al.

  2. Synthesis and characterization of functionalized magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Biswal, Dipti; Peeples, Brianna N.; Spence, Destiny D.; Peeples, Caryn; Bell, Crystal N.; Pradhan, A. K.

    2012-04-01

    Magnetic nanoparticles have been used in a wide array of industrial and biomedical applications due to their unique properties at the nanoscale level. They are extensively used in magnetic resonance imaging (MRI), magnetic hyperthermia treatment, drug delivery, and in assays for biological separations. Furthermore, superparamagnetic nanoparticles are of large interest for in vivo applications. However, these unmodified nanoparticles aggregate and consequently lose their superparamagnetic behaviors, due to high surface to volume ratio and strong dipole to dipole interaction. For these reasons, surface coating is necessary for the enhancement and effectiveness of magnetic nanoparticles to be used in various applications. In addition to providing increased stability to the nanoparticles in different solvents or media, stabilizers such as surfactants, organic/inorganic molecules, polymer and co-polymers are employed as surface coatings, which yield magnetically responsive systems. In this work we present the synthesis and magnetic characterization of Fe3O4 nanoparticles coated with 3-aminopropyltriethoxy silane (APS) and citric acid. The particles magnetic hysteresis was measured by a superconducting quantum interference device (SQUID) magnetometer with an in-plane magnetic field. The uncoated and coated magnetic nanoparticles were characterized by using fourier transform infrared (FTIR), UV-vis, X-ray diffraction, transmission electron microscopy, and thermo-gravimetric analysis.

  3. On the birefringence of multilayered symmetric diblock copolymer films

    SciTech Connect

    Kim, J.; Chin, I.; Smith, B.A.; Russell, T.P. ); Mays, J.W. . Dept. of Chemistry)

    1993-09-27

    The chain extension at lamellar interfaces was studied in thin films of symmetric diblock copolymers on gold substrates. The first copolymer consisted of blocks of polystyrene (PS) and poly(2-vinylpyridine) (P2VP), denoted P(S-b-2VP). The second was a diblock copolymer of PS and poly(methyl methacrylate) (PMMA), denoted P(S-b-MMA), on a gold substrate. Using attenuated total reflectance spectroscopy, the refractive indices parallel, n[sub [parallel

  4. Reversible geling co-polymer and method of making

    DOEpatents

    Gutowska, Anna

    2005-12-27

    The present invention is a thereapeutic agent carrier having a thermally reversible gel or geling copolymer that is a linear random copolymer of an [meth-]acrylamide derivative and a hydrophilic comonomer, wherein the linear random copolymer is in the form of a plurality of linear chains having a plurality of molecular weights greater than or equal to a minimum geling molecular weight cutoff and a therapeutic agent.

  5. Diblock Copolymers under Nano-Confinement

    NASA Astrophysics Data System (ADS)

    Meng, Dong; Yin, Yuhua; Wang, Qiang

    2009-03-01

    Nano-confinement strongly affects and can thus be used to control the self-assembled morphology of block copolymers. Understanding such effects is of both fundamental and practical interest. In this work, we use real-space self-consistent field calculations with high accuracy to study the self-assembled morphology of diblock copolymers (DBC) under nano-confinement for several systems, including 1D lamellae-forming DBC confined between two homogeneous and parallel surfaces, in nano-pores, and on topologically patterned substrates; 2D cylinder-forming DBC on chemically strip-patterned substrates; and 3D gyroid- forming DBC confined between two homogeneous and parallel surfaces. The stable phases are identified through free-energy comparison, and our SCF results are compared with available experiments and Monte Carlo simulations in each case.

  6. Photothermal degradation of ethylene/vinylacetate copolymer

    NASA Technical Reports Server (NTRS)

    Liang, R. H.; Chung, S.; Clayton, A.; Di Stefano, S.; Oda, K.; Hong, S. D.; Gupta, A.

    1983-01-01

    Photothermal degradation studies were conducted on a 'stabilized' formulation of ethylene/vinyl acetate copolymer (EVA) in the temperature range 25-105 C under three different oxygen environments (in open air, with limited access to O2, and in a dark closed stagnant oven). These studies were performed in order to evaluate the utility of EVA as an encapsulation material for photovoltaic modules. Results showed that at low temperature (25 C), slow photooxidation of the polymer occurred via electronic energy transfer involving the UV absorber incorporated in the polymer. However, no changes in the physical properties of the bulk polymer were detected up to 1500 hours of irradiation. At elevated temperatures, leaching and evaporation of the additives occurred, which ultimately resulted in the chemical crosslinking of the copolymer and the formation of volatile photoproducts such as acetic acid.

  7. Rapid ordering of block copolymer thin films.

    PubMed

    Majewski, Pawel W; Yager, Kevin G

    2016-10-12

    Block-copolymers self-assemble into diverse morphologies, where nanoscale order can be finely tuned via block architecture and processing conditions. However, the ultimate usage of these materials in real-world applications may be hampered by the extremely long thermal annealing times-hours or days-required to achieve good order. Here, we provide an overview of the fundamentals of block-copolymer self-assembly kinetics, and review the techniques that have been demonstrated to influence, and enhance, these ordering kinetics. We discuss the inherent tradeoffs between oven annealing, solvent annealing, microwave annealing, zone annealing, and other directed self-assembly methods; including an assessment of spatial and temporal characteristics. We also review both real-space and reciprocal-space analysis techniques for quantifying order in these systems. PMID:27537062

  8. Hierarchical porous polymer scaffolds from block copolymers.

    PubMed

    Sai, Hiroaki; Tan, Kwan Wee; Hur, Kahyun; Asenath-Smith, Emily; Hovden, Robert; Jiang, Yi; Riccio, Mark; Muller, David A; Elser, Veit; Estroff, Lara A; Gruner, Sol M; Wiesner, Ulrich

    2013-08-01

    Hierarchical porous polymer materials are of increasing importance because of their potential application in catalysis, separation technology, or bioengineering. Examples for their synthesis exist, but there is a need for a facile yet versatile conceptual approach to such hierarchical scaffolds and quantitative characterization of their nonperiodic pore systems. Here, we introduce a synthesis method combining well-established concepts of macroscale spinodal decomposition and nanoscale block copolymer self-assembly with porosity formation on both length scales via rinsing with protic solvents. We used scanning electron microscopy, small-angle x-ray scattering, transmission electron tomography, and nanoscale x-ray computed tomography for quantitative pore-structure characterization. The method was demonstrated for AB- and ABC-type block copolymers, and resulting materials were used as scaffolds for calcite crystal growth. PMID:23908232

  9. Phase Behavior of Gradient Copolymer Solution

    NASA Astrophysics Data System (ADS)

    Pandav, Gunja; Gallow, Keith; Loo, Yueh-Lin; Ganesan, Venkat

    2012-02-01

    We study the behavior of amphiphilic linear gradient copolymer chains under poor solvent conditions. Using Bond Fluctuation model and parallel tempering algorithm, we explore qualitative behavior of this class of polymers with varying gradient strength; which is the largest difference in the instantaneous composition along the polymer chain. Under poor solvent conditions, the chains collapse to form micelles. We find a linear dependence of hydrophilic to hydrophobic transition temperature on gradient strength. Systematic analysis of these clusters reveals a strong dependence of micelle properties on gradient strength. Also, we discuss our results with reference to recent experiments on synthesis and cloud point depression in gradient copolymers confirming gradient strength as key parameter in tuning micelle properties.

  10. Multigraft Copolymer Superelastomers: Synthesis Morphology, and Properties

    SciTech Connect

    Uhrig, David; Schlegel, Ralf; Weidisch, Roland; Mays, Jimmy

    2011-01-01

    The synthesis of well-defined multigraft copolymers having a polydiene backbone with polystyrene side chains is briefly reviewed, with particular focus on controlling branch point spacing and branch point functionality. Use of living anionic polymerization and chlorosilane linking chemistry has led to the synthesis of series of materials having regularly spaced trifunctional (comb), tetrafunctional (centipede), and hexafunctional (barbwire) branch points. The morphologies of these materials were characterized by transmission electron microscopy and small-angle X-ray scattering, and it was found that the morphologies were controlled by the local architectural asymmetry associated with each branch point. Mechanical properties studies revealed that such multigraft copolymers represent a new class of thermoplastic elastomers (TPEs) with superior elongation at break and low residual strains as compared to conventional TPEs.

  11. Structure Formation of Block Copolymer Membranes

    NASA Astrophysics Data System (ADS)

    Abetz, Volker

    2013-03-01

    Isoporous membranes have received increasing attention during the last couple of years. The advantage of these materials is to give access to membranes with a very high number density of pores with controlled diameters, thus leading to ultrafiltration membranes with a very high permeability, and simultaneously also with a very high selectivity in terms of size exclusion. Different approaches have been reported, which typically involve the transfer of a thin block copolymer film from a solid to a porous support, eventually followed by an edging step. An alternative strategy is to form integral asymmetric membranes, where the thin top layer is continuously changing into a spongy support layer, thus avoiding the build-up of mechanical stresses. This happens by subjecting the cast polymer solution film into a precipitant, inducing the so-called phase inversion by exchange of solvent with the non-solvent. Here it is important to have a system where solvent and nonsolvent are fully miscible. This strategy also enables the direct formation of open pores without a subsequent edging step, if the solvents and nonsolvents are appropriately chosen. Different types of amphiphilic block copolymers based on styrene, 2- or 4-vinyl pyridine, and ethylene oxide with various compositions and molecular weights will be discussed. These block copolymers were dissolved at different concentrations in various solvent mixtures, and then cast on a non-woven support, which was either pretreated with a liquid, or not. Varying the time before the cast solution was subjected to phase inversion, as well as choosing the temperature of the precipitation bath, are further parameters having strong influence on the obtained membrane film structure. Membranes with pore forming blocks showing pH or temperature sensitive behaviour can be reversibly switched from an open state to a closed state. The size of the pores can be controlled by both molecular weight and composition of the block copolymers.

  12. Critical adsorption of copolymer tethered on selective surfaces

    NASA Astrophysics Data System (ADS)

    Li, Hong; Qian, Chang-Ji; Luo, Meng-Bo

    2016-04-01

    Critical adsorption behaviors of flexible copolymer chains tethered to a flat homogeneous surface are studied by using Monte Carlo simulations. We have compared the critical adsorption temperature Tc, estimated by a finite-size scaling method, for different AB copolymer sequences with A the attractive monomer and B the inert monomer. We find that Tc increases with an increase in the fraction of monomers A, fA, in copolymers, and it increases with an increase in the length of block A for the same fA. In particular, Tc of copolymer (AnBn)r can be expressed as a function of the block length, n, and Tc of copolymer (AnB)r and (ABm)r can be expressed as a linear function of fA. Tc of random copolymer chains also can be expressed as a linear function of fA and it can be estimated by using weight-average of Tc of different diblocks in the random copolymer. However, the crossover exponent is roughly independent of AB sequence distributions either for block copolymers or for random copolymers.

  13. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... polymerized copolymer of ethyl acrylate, methyl methacrylate, and methacrylic acid applied in emulsion form to... Glyceryl monostearate Methyl cellulose Mineral oil Paraffin wax Potassium hydroxide Potassium...

  14. Plasmonic nanoparticles tuned thermal sensitive photonic polymer for biomimetic chameleon

    NASA Astrophysics Data System (ADS)

    Yan, Yang; Liu, Lin; Cai, Zihe; Xu, Jiwen; Xu, Zhou; Zhang, Di; Hu, Xiaobin

    2016-08-01

    Among many thermo-photochromic materials, the color-changing behavior caused by temperature and light is usually lack of a full color response. And the study on visible light-stimuli chromic response is rarely reported. Here, we proposed a strategy to design a thermo-photochromic chameleon biomimetic material consisting of photonic poly(N-isopropylacrylamide-co-methacrylic acid) copolymer and plasmonic nanoparticles which has a vivid color change triggered by temperature and light like chameleons. We make use of the plasmonic nanoparticles like gold nanoparticles and silver nanoparticles to increase the sensitivity of the responsive behavior and control the lower critical solution temperature of the thermosensitive films by tuning the polymer chain conformation transition. Finally, it is possible that this film would have colorimetric responses to the entire VIS spectrum by the addition of different plasmonic nanoparticles to tune the plasmonic excitation wavelength. As a result, this method provides a potential use in new biosensors, military and many other aspects.

  15. Gyroid nickel nanostructures from diblock copolymer supramolecules.

    PubMed

    Vukovic, Ivana; Punzhin, Sergey; Voet, Vincent S D; Vukovic, Zorica; de Hosson, Jeff Th M; ten Brinke, Gerrit; Loos, Katja

    2014-01-01

    Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex - polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template's channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology. PMID:24797367

  16. Crystallization in Ordered Polydisperse Polyolefin Diblock Copolymers

    SciTech Connect

    Li, Sheng; Register, Richard A.; Landes, Brian G.; Hustad, Phillip D.; Weinhold, Jeffrey D.

    2010-12-07

    The morphologies of polydisperse ethylene-octene diblock copolymers, synthesized via a novel coordinative chain transfer polymerization process, are examined using two-dimensional synchrotron small-angle and wide-angle X-ray scattering on flow-aligned specimens. The diblock copolymers comprise one amorphous block with high 1-octene content and one semicrystalline block with relatively low 1-octene content, and each block ideally exhibits the most-probable distribution. Near-symmetric diblocks with a sufficiently large octene differential between the amorphous and semicrystalline blocks show well-ordered lamellar domain structures with long periods exceeding 100 nm. Orientation of these domain structures persists through multiple melting/recrystallization cycles, reflecting a robust structure which self-assembles in the melt. The domain spacings are nearly 3-fold larger than those in near-monodisperse polyethylene block copolymers of similar molecular weights. Although the well-ordered lamellar domain structure established in the melt is preserved in the solid state, the crystallites are isotropic in orientation. These materials display crystallization kinetics consistent with a spreading growth habit, indicating that the lamellae do not confine or template the growing crystals. The exceptionally large domain spacings and isotropic crystal growth are attributed to interblock mixing resulting from the large polydispersity; short hard blocks dissolved in the soft-block-rich domains swell the domain spacing in the melt and allow hard block crystallization to proceed across the lamellar domain interfaces.

  17. Sulfonated Polymerized Ionic Liquid Block Copolymers.

    PubMed

    Meek, Kelly M; Elabd, Yossef A

    2016-07-01

    The successful synthesis of a new diblock copolymer, referred to as sulfonated polymerized ionic liquid (PIL) block copolymer, poly(SS-Li-b-AEBIm-TFSI), is reported, which contains both sulfonated blocks (sulfonated styrene: SS) and PIL blocks (1-[(2-acryloyloxy)ethyl]-3-butylimidazolium: AEBIm) with both mobile cations (lithium: Li(+) ) and mobile anions (bis(trifluoromethylsulfonyl)imide: TFSI(-) ). Synthesis consists of polymerization via reversible addition-fragmentation chain transfer, followed by post-functionalization reactions to covalently attach the imidazolium cations and sulfonic acid anions to their respective blocks, followed by ion exchange metathesis resulting in mobile Li(+) cations and mobile TFSI(-) anions. Solid-state films containing 1 m Li-TFSI salt dissolved in ionic liquid result in an ion conductivity of >1.5 mS cm(-1) at 70 °C, where small-angle X-ray scattering data indicate a weakly ordered microphase-separated morphology. These results demonstrate a new ion-conducting block copolymer containing both mobile cations and mobile anions. PMID:27125600

  18. Block and Graft Copolymers of Polyhydroxyalkanoates

    NASA Astrophysics Data System (ADS)

    Marchessault, Robert H.; Ravenelle, François; Kawada, Jumpei

    2004-03-01

    Polyhydroxyalkanoates (PHAs) were modified for diblock copolymer and graft polymer by catalyzed transesterification in the melt and by chemical synthesis to extend the side chains of the PHAs, and the polymers were studied by transmission electron microscopy (TEM) X-ray diffraction, thermal analysis and nuclear magnetic resonance (NMR). Catalyzed transesterification in the melt is used to produce diblock copolymers of poly[3-hydroxybutyrate] (PHB) and monomethoxy poly[ethylene glycol] (mPEG) in a one-step process. The resulting diblock copolymers are amphiphilic and self-assemble into sterically stabilized colloidal suspensions of PHB crystalline lamellae. Graft polymer was synthesized in a two-step chemical synthesis from biosynthesized poly[3-hydroxyoctanoate-co-3-hydroxyundecenoate] (PHOU) containing ca. 25 mol chains. 11-mercaptoundecanoic acid reacts with the side chain alkenes of PHOU by the radical addition creating thioether linkage with terminal carboxyl functionalities. The latter groups were subsequently transformed into the amide or ester linkage by tridecylamine or octadecanol, respectively, producing new graft polymers. The polymers have different physical properties than poly[3-hydroxyoctanoate] (PHO) which is the main component of the PHOU, such as non-stickiness and higher thermal stability. The combination of biosynthesis and chemical synthesis produces a hybrid thermoplastic elastomer with partial biodegradability.

  19. Regulating block copolymer phases via selective homopolymers.

    PubMed

    Yang, Shuang; Lei, Zhen; Hu, Nan; Chen, Er-Qiang; Shi, An-Chang

    2015-03-28

    The phase behavior of strongly segregated AB diblock copolymer and selective C homopolymer blends is examined theoretically using a combination of strong stretching theory (SST) and self-consistent field theory (SCFT). The C-homopolymer is immiscible with the B-blocks but strongly attractive with the A-blocks. The effect of homopolymer content on the order-order phase transitions is analyzed. It is observed that, for AB diblock copolymers with majority A-blocks, the addition of the C-homopolymers results in lamellar to cylindrical to spherical phase transitions because of the A/C complexation. For diblock copolymers with minor A-blocks, adding C-homopolymers leads to transitions from spherical or cylindrical morphology with A-rich core to lamellae to inverted cylindrical and spherical morphologies with B-rich core. The results from analytical SST and numerical SCFT are in good agreement within most regions of the phase diagram. But the deviation becomes more obvious when the composition of A-blocks is too small and the content of added C-homopolymers is large enough, where the SCFT predicts a narrow co-existence region between different ordered phases. Furthermore, it is found that the phase behavior of the system is insensitive to the molecular weight of C-homopolymer. PMID:25833605

  20. Gyroid Nickel Nanostructures from Diblock Copolymer Supramolecules

    PubMed Central

    Vukovic, Ivana; Punzhin, Sergey; Voet, Vincent S. D.; Vukovic, Zorica; de Hosson, Jeff Th. M.; ten Brinke, Gerrit; Loos, Katja

    2014-01-01

    Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex - polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template's channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology. PMID:24797367

  1. Regulating block copolymer phases via selective homopolymers

    SciTech Connect

    Yang, Shuang E-mail: eqchen@pku.edu.cn; Lei, Zhen; Hu, Nan; Chen, Er-Qiang E-mail: eqchen@pku.edu.cn; Shi, An-Chang

    2015-03-28

    The phase behavior of strongly segregated AB diblock copolymer and selective C homopolymer blends is examined theoretically using a combination of strong stretching theory (SST) and self-consistent field theory (SCFT). The C-homopolymer is immiscible with the B-blocks but strongly attractive with the A-blocks. The effect of homopolymer content on the order-order phase transitions is analyzed. It is observed that, for AB diblock copolymers with majority A-blocks, the addition of the C-homopolymers results in lamellar to cylindrical to spherical phase transitions because of the A/C complexation. For diblock copolymers with minor A-blocks, adding C-homopolymers leads to transitions from spherical or cylindrical morphology with A-rich core to lamellae to inverted cylindrical and spherical morphologies with B-rich core. The results from analytical SST and numerical SCFT are in good agreement within most regions of the phase diagram. But the deviation becomes more obvious when the composition of A-blocks is too small and the content of added C-homopolymers is large enough, where the SCFT predicts a narrow co-existence region between different ordered phases. Furthermore, it is found that the phase behavior of the system is insensitive to the molecular weight of C-homopolymer.

  2. Comparing Fluid and Elastic Block Copolymer Shells

    NASA Astrophysics Data System (ADS)

    Rozairo, Damith; Croll, Andrew B.

    2014-03-01

    Emulsions can be stabilized with the addition of an amphiphilic diblock copolymer, resulting in droplets surrounded and protected by a polymer monolayer. Such droplets show considerable promise as advanced cargo carriers in pharmaceuticals or cosmetics due to their strength and responsiveness. Diblock copolymer interfaces remain mostly fluid and may not be able to attain the mechanical performance desired by industry. To strengthen block copolymer emulsion droplets we have developed a novel method for creating thin elastic shells using polystyrene-b-poly(acrylic acid)-b-polystyrene (PS-PAA-PS). Characterization of the fluid filled elastic shells is difficult with traditional means which lead us to develop a new and general method of mechanical measurement. Specifically, we use laser scanning confocal microscopy to achieve a high resolution measure of the deformation of soft spheres under the influence of gravity. To prove the resilience of the technique we examine both a polystyrene-b-poly(ethylene oxide) (PS-PEO) stabilized emulsion and the PS-PAA-PS emulsion. The mechanical measurement allows the physics of the polymer at the interface to be examined, which will ultimately lead to the rational development of these technologies.

  3. Sulfur copolymers for infrared optical imaging

    NASA Astrophysics Data System (ADS)

    Namnabat, S.; Gabriel, J. J.; Pyun, J.; Norwood, R. A.; Dereniak, E. L.; van der Laan, J.

    2014-06-01

    The development of organic polymers with low infrared absorption has been investigated as a possible alternative to inorganic metal oxide, semiconductor, or chalcogenide-based materials for a variety of optical devices and components, such as lenses, goggles, thermal imaging cameras and optical fibers. In principle, organic-based polymers are attractive for these applications because of their low weight, ease of processing, mechanical toughness, and facile chemical variation using commercially available precursors. Herein we report on the optical characterization of a new class of sulfur copolymers that are readily moldable, transparent above 500 nm, possess high refractive index (n > 1.8) and take advantage of the low infrared absorption of S-S bonds for potential use in the mid-infrared at 3-5 microns. These materials are largely made from elemental sulfur by an inverse vulcanization process; in the current study we focus on the properties of a chemically stable, branched copolymer of poly(sulfur-random-1,3-diisopropenylbenzene) (poly(S-r- DIB). Copolymers with elemental sulfur content ranging from 50% to 80% by weight were studied by UV-VIS spectroscopy, FTIR, and prism coupling for refractive index measurement. Clear correlation between material composition and the optical properties was established, confirming that the high polarizability of the sulfur atom leads to high refractive index while also maintaining low optical loss in the infrared.

  4. Tunable assembly of nanoparticles on patterned porous film.

    PubMed

    Ke, Bei-Bei; Wan, Ling-Shu; Chen, Peng-Cheng; Zhang, Lu-Yao; Xu, Zhi-Kang

    2010-10-19

    This paper describes an approach to fully selective assembly of nanoparticles on patterned porous surface. Copolymers of polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) synthesized by atom transfer radical polymerization were used to prepare honeycomb-patterned porous films by the breath figure method. The regularity and pore size of the films can be modulated by changing the polymer composition and casting conditions such as concentration and airflow speed. Positively charged films were fabricated directly from the quaternized copolymers or by surface quaternization. X-ray photoelectron spectroscopy and adsorption of negatively charged fluorescein sodium salt confirmed the quaternization. Then assembly of negatively charged silica nanoparticles from its aqueous dispersion was performed. Results indicate that they assemble on the external surface of patterned porous films that without prewetting. For prewetted films, the nanoparticles assemble both on the external surface and in the pores. Poly(acrylic acid) deposited from its aqueous solution can serve as an effective blocking layer, which directs the selective assembly of nanoparticles into the pores, instead of the external surface of the film. It is concluded that the Cassie-Wenzel transition is the key to the selective assembly on the highly porous films. The well-defined selective assembly forms unique hierarchical structures of nanoparticles and greatly enlarges the diversity of structures of nanoparticle aggregates. This general approach also opens a straightforward route to the selective modification of patterned porous films. PMID:20849141

  5. In situ nanofabrication of hybrid PEG-dendritic-inorganic nanoparticles and preliminary evaluation of their biocompatibility.

    PubMed

    Sousa-Herves, Ana; Sánchez Espinel, Christian; Fahmi, Amir; González-Fernández, África; Fernandez-Megia, Eduardo

    2015-03-01

    An in situ template fabrication of inorganic nanoparticles using carboxylated PEG-dendritic block copolymers of the GATG family is described as a function of the dendritic block generation, the metal (Au, CdSe) and metal molar ratio. The biocompatibility of the generated nanoparticles analysed in terms of their aggregation in physiological media, cytotoxicity and uptake by macrophages relates to the PEG density of the surface of the hybrids. PMID:25530028

  6. Developing Precisely Defined Drug-Loaded Nanoparticles by Ring-Opening Polymerization of a Paclitaxel Prodrug.

    PubMed

    Liu, Jinyao; Pang, Yan; Bhattacharyya, Jayanta; Liu, Wenge; Weitzhandler, Isaac; Li, Xinghai; Chilkoti, Ashutosh

    2016-08-01

    Nanoparticles with high paclitaxel (PTX) loading and low systemic toxicity are prepared in scalable and versatile manner via one-step ring-opening polymerization of a prodrug monomer consisting of PTX that is appended to a cyclic carbonate through a hydrolysable ester linker. Initiating this monomer from a hydrophilic macroinitiator results in an amphiphilic diblock copolymer that spontaneously self-assembles into well-defined nanoparticles with tunable size. PMID:27111757

  7. Anionic synthesis of block copolymers for photonics applications

    NASA Astrophysics Data System (ADS)

    Garces Cortes, Camila

    Anionic synthesis of well-defined polystyrene-block-polyvinylpyridine copolymers required the use of special conditions including lithium chloride and 1,1-diphenylethylene as additives, low temperature of reaction (-78°C), highly diluted monomer at -78°C and efficient stirring (Morton-type, creased reactor). Low molecular weight polystyrene-block-poly(2-vinylpyridine) copolymers (Mn = 6000 g/mol) were synthesized with average-molecular weights in agreement with the theoretically calculated Mns and narrow Mw/Mns (≤1.1). Polystyrene-block-polyvinylpyridine copolymers were selected for the fabrication of uniformly dispersed metal oxide nanoparticles (cobalt and iron oxides) due to the coordinating ligand character of the vinylpyridine units. The incorporation of the inorganic salts (1 mol-eq of inorg. salt per mol of vinylpyridine units) was 57 wt% when polystyrene- block-poly(2-vinylpyridine-co-4-vinylpyridine) (M n = 59,000 g/mol, Mw/Mn = 1.09, fv PVP = 0.19) was used and 18 wt% when polystyrene-block-poly(2-vinylpyridine) (Mn = 39,000 g/mol, Mw/Mn = 1.07, f v PVP = 0.14) was used. The end-capping reaction of polymeric chain-ends with 1,1-diphenylethylene (DPE) was studied using 2D NMR spectroscopic and MALDI-TOF mass spectrometric analyses. Oligomerization of DPE was observed using a 15-fold excess of DPE in the end-capping of poly(butadienyl)lithium (Mn = 2,200 g/mol, Mw/Mn = 1.06) but not in the case of poly(styryl)lithium (Mn = 2,000 g/mol, Mw/Mn = 1.02). Although oligomerization of DPE has been previously reported in the synthesis of 1,1-diphenylhexyllithium (6-11% oligomer with 5.4-fold excess of DPE), there are no studies showing the presence of DPE oligomer in the end-capping reaction of polymeric living carbanions. Additionally, the synthesis of poly(para-phenylene) has been studied using different precursor polymers [poly(1,3-cyclohexadienes) (Mn = 1,600 and 3,100 g/mol, Mw/Mn = 1.1 and 1.03) and poly(2-phenyl-1,3-cyclohexadiene) (Mn = 10,000 g/mol, Mw

  8. Soft-shear induced phase-separated nanoparticle string-structures in polymer thin films.

    PubMed

    Zhang, Ren; Lee, Bongjoon; Bockstaller, Michael R; Al-Enizi, Abdullah M; Elzatahry, Ahmed; Berry, Brian C; Karim, Alamgir

    2016-04-12

    Application of shear stress has been shown to unidirectionally orient the microstructures of block copolymers and polymer blends. In the present work, we study the phase separation of a novel nanoparticle (NP)-polymer blend thin film system under shear using a soft-shear dynamic zone annealing (DZA-SS) method. The nanoparticles are densely grafted with polymer chains of chemically dissimilar composition from the matrix polymer, which induces phase separation upon thermal annealing into concentrated nanoparticle domains. We systematically examine the influence of DZA-SS translation speed and thus the effective shear rate on nanoparticle domain elongation and compare this with the counterpart binary polymer blend behavior. Unidirectionally aligned nanoparticle string-domains are fabricated in the presence of soft-shear in confined thin film geometry. We expect this DZA-SS method to be applicable to various NP-polymer blends towards unidirectionally aligned nanoparticle structures, which are important to functional nanoparticle structure fabrication. PMID:26814827

  9. In situ nanofabrication of hybrid PEG-dendritic-inorganic nanoparticles and preliminary evaluation of their biocompatibility

    NASA Astrophysics Data System (ADS)

    Sousa-Herves, Ana; Sánchez Espinel, Christian; Fahmi, Amir; González-Fernández, África; Fernandez-Megia, Eduardo

    2015-02-01

    An in situ template fabrication of inorganic nanoparticles using carboxylated PEG-dendritic block copolymers of the GATG family is described as a function of the dendritic block generation, the metal (Au, CdSe) and metal molar ratio. The biocompatibility of the generated nanoparticles analysed in terms of their aggregation in physiological media, cytotoxicity and uptake by macrophages relates to the PEG density of the surface of the hybrids.An in situ template fabrication of inorganic nanoparticles using carboxylated PEG-dendritic block copolymers of the GATG family is described as a function of the dendritic block generation, the metal (Au, CdSe) and metal molar ratio. The biocompatibility of the generated nanoparticles analysed in terms of their aggregation in physiological media, cytotoxicity and uptake by macrophages relates to the PEG density of the surface of the hybrids. Electronic supplementary information (ESI) available: Structure of carboxylated PEG-GATG copolymers, aggregation of CdSe NPs in serum, and cytotoxicity of PEG-GATG copolymers. See DOI: 10.1039/c4nr06155a

  10. RAFT polymerization kinetics and polymer characterization of P3HT rod-coil block copolymers and their uses to prepare hybrid nanocomposites

    NASA Astrophysics Data System (ADS)

    Kern, Melissa Robin

    group reactions result in P3HT homopolymer in the final sample. Therefore accurate characterization requires molecular weight determination of the block copolymer and quantification of the sample composition. Also presented in this work is the synthesis of amphiphilic rod-coil block copolymers of P3HT with poly(4-vinyl pyridine) (4VP) and poly(acrylic acid) (AA). Here, P3HT-b-PAA is prepared by the direct synthesis of acrylic acid with the macroRAFT agent using a binary solvent system of trichlorobenzene and dioxane to maintain polymer solubility throughout the polymerization. The micelle formation of the resulting block copolymer is detailed as the transparent micelle solution of P3HT-b-PAA exhibits the optical behavior of solid-state P3HT. Finally, the preparation of various nanocomposites from the synthesized P3HT homopolymer and block copolymers is presented. In the first method, the RAFT end group of the P3HT macroRAFT agent and the P3HT block copolymers is reduced to a thiol to allow for attachment to Au nanoparticles. While Au nanoparticles are not useful for photovoltaic applications, the surface modification demonstrates the utility of the P3HT macroRAFT agent, which is used to modify the surface with P3HT homopolymer and P3HT block copolymers. The second method to prepare P3HT hybrid nanocomposites is in-situ growth of CdS in P3HT-b-P4VP. With analysis by dynamic light scattering (DLS), Fourier-transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM), it is concluded that a majority of the CdS growth in the P3HT-b-P4VP was confined to the P4VP block.

  11. Piezoelectric Properties of Non-Polar Block Copolymers

    SciTech Connect

    Pester, Christian; Ruppel, Markus A; Schoberth, Heiko; Schmidt, K.; Liedel, Clemens; Van Rijn, Patrick; Littrell, Ken; Schindler, Kerstin; Hiltl, Stephanie; Czubak, Thomas; Mays, Jimmy; Urban, Volker S; Boker, Alexander

    2011-01-01

    Piezoelectric properties in non-polar block copolymers are a novelty in the field of electroactive polymers. The piezoelectric susceptibility of poly(styrene-b-isoprene) block copolymer lamellae is found to be up to an order of magnitude higher when compared to classic piezoelectric materials. The electroactive response increases with temperature and is found to be strongest in the disordered phase.

  12. Morphological studies on block copolymer modified PA 6 blends

    SciTech Connect

    Poindl, M. E-mail: christian.bonten@ikt.uni-stuttgart.de; Bonten, C. E-mail: christian.bonten@ikt.uni-stuttgart.de

    2014-05-15

    Recent studies show that compounding polyamide 6 (PA 6) with a PA 6 polyether block copolymers made by reaction injection molding (RIM) or continuous anionic polymerization in a reactive extrusion process (REX) result in blends with high impact strength and high stiffness compared to conventional rubber blends. In this paper, different high impact PA 6 blends were prepared using a twin screw extruder. The different impact modifiers were an ethylene propylene copolymer, a PA PA 6 polyether block copolymer made by reaction injection molding and one made by reactive extrusion. To ensure good particle matrix bonding, the ethylene propylene copolymer was grafted with maleic anhydride (EPR-g-MA). Due to the molecular structure of the two block copolymers, a coupling agent was not necessary. The block copolymers are semi-crystalline and partially cross-linked in contrast to commonly used amorphous rubbers which are usually uncured. The combination of different analysis methods like atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) gave a detailed view in the structure of the blends. Due to the partial cross-linking, the particles of the block copolymers in the blends are not spherical like the ones of ethylene propylene copolymer. The differences in molecular structure, miscibility and grafting of the impact modifiers result in different mechanical properties and different blend morphologies.

  13. 40 CFR 721.10213 - Polyether polyester copolymer phosphate (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... phosphate (generic). 721.10213 Section 721.10213 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10213 Polyether polyester copolymer phosphate (generic). (a) Chemical... as polyether polyester copolymer phosphate (PMN P-09-253) is subject to reporting under this...

  14. Morphological studies on block copolymer modified PA 6 blends

    NASA Astrophysics Data System (ADS)

    Poindl, M.; Bonten, C.

    2014-05-01

    Recent studies show that compounding polyamide 6 (PA 6) with a PA 6 polyether block copolymers made by reaction injection molding (RIM) or continuous anionic polymerization in a reactive extrusion process (REX) result in blends with high impact strength and high stiffness compared to conventional rubber blends. In this paper, different high impact PA 6 blends were prepared using a twin screw extruder. The different impact modifiers were an ethylene propylene copolymer, a PA PA 6 polyether block copolymer made by reaction injection molding and one made by reactive extrusion. To ensure good particle matrix bonding, the ethylene propylene copolymer was grafted with maleic anhydride (EPR-g-MA). Due to the molecular structure of the two block copolymers, a coupling agent was not necessary. The block copolymers are semi-crystalline and partially cross-linked in contrast to commonly used amorphous rubbers which are usually uncured. The combination of different analysis methods like atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) gave a detailed view in the structure of the blends. Due to the partial cross-linking, the particles of the block copolymers in the blends are not spherical like the ones of ethylene propylene copolymer. The differences in molecular structure, miscibility and grafting of the impact modifiers result in different mechanical properties and different blend morphologies.

  15. 40 CFR 721.484 - Fluorinated acrylic copolymer (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Fluorinated acrylic copolymer (generic name). 721.484 Section 721.484 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.484 Fluorinated acrylic copolymer (generic name). (a) Chemical...

  16. 40 CFR 721.4700 - Metalated alkylphenol copolymer (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Metalated alkylphenol copolymer (generic name). 721.4700 Section 721.4700 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4700 Metalated alkylphenol copolymer (generic name). (a)...

  17. 40 CFR 721.4700 - Metalated alkylphenol copolymer (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Metalated alkylphenol copolymer (generic name). 721.4700 Section 721.4700 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4700 Metalated alkylphenol copolymer (generic name). (a)...

  18. 40 CFR 721.336 - Perfluoroalkylethyl acrylate copolymer (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Perfluoroalkylethyl acrylate copolymer (generic name). 721.336 Section 721.336 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.336 Perfluoroalkylethyl acrylate copolymer (generic name). (a)...

  19. 21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... weight of aqueous sodium chloride solution at 20 °C for 24 hours. The low molecular weight extractives... applied mass). The solvent used shall be at least 60 milliliters aqueous sodium chloride solution per gram... polyacrylate copolymers consist of: (1) The grafted copolymer of cross-linked sodium polyacrylate identified...

  20. 21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... weight of aqueous sodium chloride solution at 20 °C for 24 hours. The low molecular weight extractives... applied mass). The solvent used shall be at least 60 milliliters aqueous sodium chloride solution per gram... polyacrylate copolymers consist of: (1) The grafted copolymer of cross-linked sodium polyacrylate identified...

  1. 21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... weight of aqueous sodium chloride solution at 20 °C for 24 hours. The low molecular weight extractives... applied mass). The solvent used shall be at least 60 milliliters aqueous sodium chloride solution per gram... polyacrylate copolymers consist of: (1) The grafted copolymer of cross-linked sodium polyacrylate identified...

  2. 21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... weight of aqueous sodium chloride solution at 20 °C for 24 hours. The low molecular weight extractives... applied mass). The solvent used shall be at least 60 milliliters aqueous sodium chloride solution per gram... polyacrylate copolymers consist of: (1) The grafted copolymer of cross-linked sodium polyacrylate identified...

  3. 21 CFR 181.32 - Acrylonitrile copolymers and resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acrylonitrile copolymers and resins. 181.32 Section 181.32 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PRIOR-SANCTIONED FOOD INGREDIENTS Specific Prior-Sanctioned Food Ingredients § 181.32 Acrylonitrile copolymers and resins. (a)...

  4. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section... Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid... for use in contact with food subject to the provisions of this section. (a) The ethylene-acrylic...

  5. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the American Society for... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ethylene-carbon monoxide copolymers. 177.1312... Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon...

  6. 21 CFR 173.60 - Dimethylamine-epichlorohydrin copolymer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Polymer Adjuvants for Food Treatment § 173.60 Dimethylamine-epichlorohydrin copolymer. Dimethylamine... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Dimethylamine-epichlorohydrin copolymer. 173.60... epichlorohydrin in which not more than 5 mole-percent of dimethylamine may be replaced by an equimolar amount...

  7. Imide/arylene ether copolymers with pendent trifluoromethyl groups

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Havens, Stephen J.

    1992-01-01

    A series of imide/arylene ether block copolymers were prepared using an arylene ether block containing a hexafluoroisopropylidene group and an imide block containing a hexafluoroisopropylidene and a trifluoromethyl group in the polymer backbone. The copolymers were characterized and mechanical properties were determined and compared to the homopolymers.

  8. 40 CFR 721.10213 - Polyether polyester copolymer phosphate (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... phosphate (generic). 721.10213 Section 721.10213 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10213 Polyether polyester copolymer phosphate (generic). (a) Chemical... as polyether polyester copolymer phosphate (PMN P-09-253) is subject to reporting under this...

  9. 40 CFR 721.10213 - Polyether polyester copolymer phosphate (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... phosphate (generic). 721.10213 Section 721.10213 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10213 Polyether polyester copolymer phosphate (generic). (a) Chemical... as polyether polyester copolymer phosphate (PMN P-09-253) is subject to reporting under this...

  10. 40 CFR 721.10213 - Polyether polyester copolymer phosphate (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... phosphate (generic). 721.10213 Section 721.10213 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10213 Polyether polyester copolymer phosphate (generic). (a) Chemical... as polyether polyester copolymer phosphate (PMN P-09-253) is subject to reporting under this...

  11. Block Copolymer Templates for Optical Materials and Devices

    NASA Astrophysics Data System (ADS)

    Urbas, Augustine; Martin, Maldovan; Carter, W. C.; Thomas, E. L.; Fasolka, Michael; Fraser, Cassandra

    2002-03-01

    Block copolymers can act as super-lattices for creating novel optical structures. We have fabricated block copolymer photonic crystals from one, two and three dimensionally periodic systems and have enhanced their dielectric properties towards creating complete 3D band gaps. By using carefully selected blends of linear and star block copolymers, we are able to create hierarchical blends which exhibit precise molecular positioning of fluorescent molecules. We are exploring these unique patterning capabilities of block copolymer systems for the formation of ordered arrays of optically active components within a photonic crystal. Precise location of both fluorescent and nonlinear components within block copolymer photonic crystals affords new opportunities for creating low threshold, upconverting and array lasers as well as optical modulators and other photonic devices.

  12. Light-emitting block copolymers composition, process and use

    DOEpatents

    Ferraris, John P.; Gutierrez, Jose J.

    2006-11-14

    Generally, and in one form, the present invention is a composition of light-emitting block copolymer. In another form, the present invention is a process producing a light-emitting block copolymers that intends polymerizing a first di(halo-methyl) aromatic monomer compound in the presence of an anionic initiator and a base to form a polymer and contacting a second di(halo-methyl) aromatic monomer compound with the polymer to form a homopolymer or block copolymer wherein the block copolymer is a diblock, triblock, or star polymer. In yet another form, the present invention is an electroluminescent device comprising a light-emitting block copolymer, wherein the electroluminescent device is to be used in the manufacturing of optical and electrical devices.

  13. Crystallization and Solid State Structure of Poly(lactide) Copolymers

    NASA Astrophysics Data System (ADS)

    Baratian, S.; Runt, J.; Hall, E.; Lin, J. S.

    2000-03-01

    A series of random poly(lactide) copolymers was synthesized from L-lactide and D,L lactide using a tin (II) octanoate catalyst. The copolymers contained from 1.7 to 6.2 percent R stereochemical defects in otherwise S stereoisomer chains. Small-angle x-ray scattering experiments were used to determine the final lamellar microstructure of the copolymers. Lamellar thicknesses were strongly dependent on R co-unit concentration and it was concluded that the final structure contains significant pockets of non-crystalline material between spherulite fibrils. Equilibrium melting temperatures were estimated using the Gibbs-Thomson approach and their variation with comonomer content suggests that there is significant exclusion of R stereochemical defects from crystalline regions. Spherulite growth rates of the D-lactide copolymers were found to be larger than L-lactide/meso-lactide copolymers at equivalent optical composition.

  14. Preparation and Morphology of ABn Mictoarm Block Copolymers

    NASA Astrophysics Data System (ADS)

    Takano, Atsushi; Watanabe, Momoka; Asai, Yusuke; Suzuki, Jiro; Matsushita, Yushu

    A series of ABn mictoarm block copolymers (bottle brush copolymers) consisting of polystyrene (S) as a backbone and polyisoprenes (I) as grafts were precisely synthesized by an anionic polymerization, and their microphase-separated structures were investigated by transmission electron microscopy (TEM) and small-angle X-ray scattering(SAXS). A copolymer with composition of φS =0.57 and number of grafts(n) of 10 shows characteristic cylindrical structure, where microdomains of S reveals hexagonal cross section with non-constant mean curvature interface. While a sample with composition of φS =0.37 and number of grafts(n) of 40 shows spherical structure with rather large S isolated domains and characteristic domain packing manner was found. Furthermore composition dependence of microphase-separated structures for SIn mictoarm block copolymers were investigated and compared to SI diblock copolymer system.

  15. Directed Ordering of Block Copolymer Thin Films with Flexible Interfaces for Functional Materials

    NASA Astrophysics Data System (ADS)

    Karim, Alamgir

    2012-02-01

    Orientation control of block copolymer (BCP) films is important for advanced technological applications. We present studies on directed ordering of block copolymer thin films on rigid substrates such as quartz to elastomeric PDMS and flexible Kapton substrates for tunable orientation of microphase separated poly (styrene) -- block -poly (methylmethacrylate) (PS-PMMA) cylinder and lamellae forming BCP films. Although the crosslinked PDMS has low surface energy, its surface energy can be tuned by exposing to UV-Ozone (UVO) that presents an opportunity to change BCP-PDMS interfacial energy to control BCP orientation across full range of orientation and film wettability. On the other hand, Kapton offers a near neutral surface for PS-PMMA without surface modification. Via a modified version of a dynamic thermal processing termed cold zone annealing-sharp (CZA-S), we obtain a wide range of orientations of the block copolymer films in unfilled and nanoparticle filled systems with an interest in photovoltaic systems. With CZA-S, vertical orientation of PS-PMMA can be obtained in films as thick as 1 micron with etchable PMMA domains for membrane applications. GISAXS characterization of these etched BCP membranes reveals up to 5 orders of diffraction indicating hexagonally packed vertical nanopores that extend throughout the film. Under similar thermal gradient, but static conditions, temporally stable vertical cylinders form only within a narrow zone of maximum temperature gradient. Primary CZA-S ordering mechanism thus involves propagating this narrow vertically oriented zone of BCP cylinders created at the maximum thermal gradient section, across the film. An optimal speed is needed since the process competes with preferential surface wetting dynamics that favors parallel orientation. These results are reproduced on large area flexible films on a prototype dynamic R2R assembly platform with incorporated multi-CZA gradient for thin (100 nm) BCP films currently.

  16. Materials Design for Block Copolymer Lithography

    NASA Astrophysics Data System (ADS)

    Sweat, Daniel Patrick

    Block copolymers (BCPs) have attracted a great deal of scientific and technological interest due to their ability to spontaneously self-assemble into dense periodic nanostructures with a typical length scale of 5 to 50 nm. The use of self-assembled BCP thin-films as templates to form nanopatterns over large-area is referred to as BCP lithography. Directed self-assembly of BCPs is now viewed as a viable candidate for sub-20 nm lithography by the semiconductor industry. However, there are multiple aspects of assembly and materials design that need to be addressed in order for BCP lithography to be successful. These include substrate modification with polymer brushes or mats, tailoring of the block copolymer chemistry, understanding thin-film assembly and developing epitaxial like methods to control long range alignment. The rational design, synthesis and self-assembly of block copolymers with large interaction parameters (chi) is described in the first part of this dissertation. Two main blocks were chosen for introducing polarity into the BCP system, namely poly(4-hydroxystyrene) and poly(2-vinylpyridine). Each of these blocks are capable of ligating Lewis acids which can increase the etch contrast between the blocks allowing for facile pattern transfer to the underlying substrate. These BCPs were synthesized by living anionic polymerization and showed excellent control over molecular weight and dispersity, providing access to sub 5-nm domain sizes. Polymer brushes consist of a polymer chain with one end tethered to the surface and have wide applicability in tuning surface energy, forming responsive surfaces and increasing biocompatibility. In the second part of the dissertation, we present a universal method to grow dense polymer brushes on a wide range of substrates and combine this chemistry with BCP assembly to fabricate nanopatterned polymer brushes. This is the first demonstration of introducing additional functionality into a BCP directing layer and opens up

  17. Thermal Conductivity of Ethylene Vinyl Acetate Copolymer/Nanofiller Blends

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Connell, John W.; Smith, Joseph G., Jr.; Lin, Y.; Sun, Y. P.

    2007-01-01

    To reduce weight and increase the mobility, comfort, and performance of future spacesuits, flexible, thermally conductive fabrics and plastic tubes are needed for the Liquid Cooling and Ventilation Garment. Such improvements would allow astronauts to operate more efficiently and safely for extended extravehicular activities. As an approach to raise the thermal conductivity (TC) of an ethylene vinyl acetate copolymer (Elvax(TM)260), it was compounded with three types of carbon based nanofillers: multi-walled carbon nanotubes (MWCNTs), vapor grown carbon nanofibers (CNFs), and expanded graphite (EG). In addition, other nanofillers including metallized CNFs, nickel nanostrands, boron nitride, and powdered aluminum were also compounded with Elvax(TM) 260 in the melt at various loading levels. In an attempt to improve compatibility between Elvax 260 and the nanofillers, MWCNTs and EG were modified by surface coating and through noncovalent and covalent attachment of organic molecules containing alkyl groups. Ribbons of the nanocomposites were extruded to form samples in which the nanofillers were aligned in the direction of flow. Samples were also fabricated by compression molding to yield nanocomposites in which the nanofillers were randomly oriented. Mechanical properties of the aligned samples were determined by tensile testing while the degree of dispersion and alignment of nanoparticles were investigated using high-resolution scanning electron microscopy. TC measurements were performed using a laser flash (Nanoflash(TM)) technique. TC of the samples was measured in the direction of, and perpendicular to, the alignment direction. Additionally, tubing was also extruded from select nanocomposite compositions and the TC and mechanical flexibility measured.

  18. Thermoreversible hydroferrogels with tunable mechanical properties utilizing block copolymer mesophases as template.

    PubMed

    Krekhova, Marina; Lang, Tobias; Richter, Reinhard; Schmalz, Holger

    2010-12-21

    Thermoreversible hydroferrogels (FGs) have been prepared via gelation of aqueous maghemite ferrofluids (FFs) using the triblock copolymer Pluronic P123 as gelator. In the investigated concentration range of 28-42 wt % P123, long-term stable homogeneous FGs can be prepared from FFs with a maximum maghemite content of 14 wt %. For higher FF concentrations up to 29 wt %, however, homogeneous FGs were formed only for gelator contents up to ca. 33 wt %. A combination of rheology and μ-DSC was applied as an alternative method to construct the P123 phase diagram, without the need for visual methods or scattering techniques. Using this procedure, we could show that maghemite nanoparticles can be effectively templated by the cubic and hexagonal P123 mesophases in a concentration range of 33-38 wt % P123 and FF concentrations up to 14 wt %, respectively. Most importantly, the phase behavior and the corresponding phase-transition temperatures of P123 were not significantly altered. As a result, the FGs show a reversible temperature-triggered transition from a cubic hard gel to a hexagonal gel, which is linked with a softening of the gel. Furthermore, this concept can be applied to template cobalt ferrite nanoparticle effectively, too. Magnetization experiments revealed that the superparamagnetic behavior of the maghemite nanoparticles, which show a Néel type relaxation, is not altered in the corresponding FGs. In contrast, FGs based on blocked cobalt ferrite nanoparticles show a hysteretic behavior, which indicates a strong mechanical coupling between the P123 mesophase and the magnetic nanoparticles. PMID:21090823

  19. Fluctuation Dynamics of Block Copolymer Vesicles

    SciTech Connect

    Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.

    2010-07-13

    X-ray photon correlation spectroscopy was used to characterize the wave-vector- and temperature-dependent dynamics of spontaneous thermal fluctuations in a vesicle (L4) phase that occurs in a blend of a symmetric poly(styrene-ethylene/butylene-styrene) triblock copolymer with a polystyrene homopolymer. Measurements of the intermediate scattering function reveal stretched-exponential behavior versus time, with a stretching exponent slightly larger than 2/3. The corresponding relaxation rates show an approximate q{sup 3} dependence versus wave vector. Overall, the experimental measurements are well described by theories that treat the dynamics of independent membrane plaquettes.

  20. Oriented Protein Nanoarrays on Block Copolymer Template.

    PubMed

    Shen, Lei; Zhu, Jintao

    2016-03-01

    Here, a simple yet robust method is developed to fabricate oriented protein nanoarrays by employing a block copolymer (BCP) template, which presents nano-scaled spot areas at high-density arrays. Unlike the conventional BCP nanolithography, the BCP platform described here resists nonspecific protein adsorption and prevents the denaturation of immobilized proteins in aqueous solution. The orderly arranged array areas are functionalized by linking chemistry which allows for the precise control of protein orientation. This approach allows us to generate potentially oriented protein nanoarrays at high-density array spots, which is useful for miniaturized nanoarrays within high-throughput proteomic applications. PMID:26785818

  1. A amphoteric copolymer profile modification agent

    SciTech Connect

    Wang HongGuan; Yu LianCheng; Tian HongKun

    1995-11-01

    This report provides a new gel profile modification agent prepared by an amphoteric copolymer (FT-213) and a novel crosslinking agent (BY), and introduces the preparations of the amphoteric polymer, the crosslinking agent and the profile modification agent, the action mechanism, the test conditions and the evaluations of the performance of the agent. The 45 well treatments in oilfields demonstrate that the agent can be prepared conveniently, the agent has better compatibility and application performances, and the treatment life is longer with the use of the agent. 80,000 tons incremental oil and 60,000 m{sup 3} decreasing water production have been achieved.

  2. 21 CFR 175.365 - Vinylidene chloride copolymer coatings for polycarbonate film.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Vinylidene chloride copolymer coatings for... chloride copolymer coatings for polycarbonate film. Vinylidene chloride copolymer coatings identified in... chapter. (b) The coatings are prepared from vinylidene chloride copolymers produced by...

  3. 21 CFR 175.365 - Vinylidene chloride copolymer coatings for polycarbonate film.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Vinylidene chloride copolymer coatings for... chloride copolymer coatings for polycarbonate film. Vinylidene chloride copolymer coatings identified in... chapter. (b) The coatings are prepared from vinylidene chloride copolymers produced by...

  4. 21 CFR 175.365 - Vinylidene chloride copolymer coatings for polycarbonate film.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Vinylidene chloride copolymer coatings for... chloride copolymer coatings for polycarbonate film. Vinylidene chloride copolymer coatings identified in... chapter. (b) The coatings are prepared from vinylidene chloride copolymers produced by...

  5. The effect of particle size on the morphology and thermodynamics of diblock copolymer/tethered-particle membranes

    SciTech Connect

    Zhang, Bo; Edwards, Brian J.

    2015-06-07

    A combination of self-consistent field theory and density functional theory was used to examine the effect of particle size on the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Particle size was varied between one and four tenths of the radius of gyration of the diblock polymer chain for neutral particles as well as those either favoring or disfavoring segments of the copolymer blocks. Phase diagrams were constructed and analyzed in terms of thermodynamic diagrams to understand the physics associated with the molecular-level self-assembly processes. Typical morphologies were observed, such as lamellar, spheroidal, cylindrical, gyroidal, and perforated lamellar, with the primary concentration region of the tethered particles being influenced heavily by particle size and tethering location, strength of the particle-segment energetic interactions, chain length, and copolymer radius of gyration. The effect of the simulation box size on the observed morphology and system thermodynamics was also investigated, indicating possible effects of confinement upon the system self-assembly processes.

  6. Biomimetic mucin modified PLGA nanoparticles for enhanced blood compatibility.

    PubMed

    Thasneem, Y M; Rekha, M R; Sajeesh, S; Sharma, Chandra P

    2013-11-01

    Efforts to develop long circulating polymeric nanoparticles have propelled many strategies in nanoparticle surface modification to bypass immune surveillance and systemic clearance. In this context, our present study reports on the preparation and evaluation of mucin functionalized poly lactic-co-glycolic acid (PLGA) nanoparticles as hemocompatible, cell penetrating nanoparticulate drug delivery system. Amino groups of mucin were conjugated to the terminal carboxylic acid groups on PLGA to be followed by nanoparticle synthesis via standard solvent evaporation technique. Detailed in vitro experiments were performed to illustrate the significance of alternating copolymer structured mucin modified PLGA nanoparticles in terms of enhanced hemocompatibility and cellular uptake. Mucylation proved promising in controlling PLGA nanoparticle- interaction with plasma proteins (opsonins) and blood components via hemolysis, thrombogenecity and complement activation. Besides hemocompatibility, the modified and unmodified nanoparticles were also found to be cytocompatible with L929 and C6 cell lines. The fluorescent and confocal image analysis evaluated the extent of cellular uptake of nanoparticles into C6 cells. Specifically the combination of stealth properties and cellular internalization capacity of mucin modified PLGA nanoparticle (PLGA-Mucin) lead us to propose it as a safe, efficient and multifunctional nanoplatform for disease specific intravenous drug delivery applications as far as in vitro experiments are concerned. PMID:23978287

  7. Bioadhesive properties and biodistribution of cyclodextrin-poly(anhydride) nanoparticles.

    PubMed

    Agüeros, Maite; Areses, Paloma; Campanero, Miguel Angel; Salman, Hesham; Quincoces, Gemma; Peñuelas, Ivan; Irache, Juan Manuel

    2009-06-28

    This work describes the preparation, characterization and evaluation of the nanoparticles formed by the copolymer of methyl vinyl ether and maleic anhydride (Gantrez) AN) and cyclodextrins, including beta-cyclodextrin (CD) hydroxypropyl-beta-cyclodextrin (HPCD) and 6-monodeoxy-6-monoamino-beta-cyclodextrin (NHCD). The cyclodextrin-poly(anhydride) nanoparticles were prepared by a solvent displacement method and characterized by measuring the size, zeta potential, morphology and composition. For bioadhesion studies, nanoparticles were fluorescently labelled with rhodamine B isothiocianate (RBITC). For in vivo imaging biodistribution studies, (99m)Tc-labelled nanoparticles were used. Nanoparticles displayed a size of about 150nm and a cyclodextrin content which was found optimal under the following experimental conditions: cyclodextrin/poly(anhydride) ratio of 0.25 by weight, 30min of incubation time between the cyclodextrin and the polymer. Moreover, the oligosaccharide content was higher with CD than with NHCD and HPCD. Overall, cyclodextrin-poly(anhydride) nanoparticles displayed homogeneous bioadhesive interactions within the gut. The intensity of these interactions was higher than for control nanoparticles. The high bioadhesive capacity was observed for HPCD-NP and NHCD-NP which can be related with their rough morphology and, thus, a higher specific surface than for smooth nanoparticles (CD-NP). Finally, from in vivo studies, no evidence of translocation of distribution to other organs was observed when these nanoparticles were orally administered. PMID:19491010

  8. Spiropyran-based hyperbranched star copolymer: synthesis, phototropy, FRET, and bioapplication.

    PubMed

    Wang, Ying; Hong, Chun-Yan; Pan, Cai-Yuan

    2012-08-13

    Photo- and pH-responsive amphiphilic hyperbranched star copolymers, poly(6-O-methacryloyl-1,2;3,4-di-O-isopropylidene-d-galactopyranose)[poly(2-(N,N-dimethylaminoethyl) methacrylate)-co-poly(1'-(2-methacryloxyethyl)-3',3'-dimethyl-6-nitro-spiro(2H-1-benzo-pyran-2,2'-indoline))](n)s [HPMAlpGP(PDMAEMA-co-PSPMA)(n)], were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of the DMAEMA and the SPMA using hyperbranched PMAlpGP as a macro RAFT agent. In aqueous solution, the copolymers self-assembled to form core-shell micelles with HPMAlpGP core and PDMAEMA-co-PSPMA shell. The hydrophobic fluorescent dye nitrobenzoxadiazolyl derivative (NBD) was loaded into the spiropyran-containing micelles. The obtained micelles not only have the photochromic properties, but also modulate the fluorescence of NBD through fluorescence resonance energy transfer (FRET), which was also observed in living cells. Slight fluorescence intensity decrease of the spiropyran in merocyanine (ME) form was observed after five UV-visible light irradiation cycles. The cytotoxicity of the HPMAlpGP(PDMAEMA-co-PSPMA)(n) micelles was lower than that of 25k PEI. All the results revealed that these photoresponsive nanoparticles are a good candidate for cell imaging and may find broad applications in biological areas such as biological diagnosis, imaging, and detection. PMID:22759087

  9. Hierarchical pattern formation through photo-induced disorder in block copolymer/additive composite films

    NASA Astrophysics Data System (ADS)

    Yao, Li; Watkins, James

    2013-03-01

    Segregation strength in hybrid materials can be increased through selective hydrogen bonding between organic or nanoparticle additives and one block of weakly segregated block copolymers to generate well ordered hybrid materials. Here, we report the use of enantiopure tartaric acid as the additive to dramatically improve ordering in poly(ethylene oxide-block-tert-butyl acrylate) (PEO-b-PtBA) copolymers. Phase behavior and morphologies within both bulk and thin films were studied by TEM, AFM and X-ray scattering. Suppression of PEO crystallization by the interaction between tartaric acid and the PEO block enables the formation of well ordered smooth thin films. With the addition of a photo acid generator, photo-induced disorder in PEO-b-PtBA/tartaric acid composite system can be achieved upon UV exposure to deprotect PtBA block to yield poly(acrylic acid) (PAA), which is phase-miscible with PEO. Due to the strong interaction of tartaric acid with both blocks, the system undergoes a disordering transition within seconds during a post-exposure baking. With the assistance of trace-amounts of base quencher, high resolution, hierarchical patterns of sub-micron regions of ordered and disordered domains were achieved in thin films through area-selective UV exposure using a photo-mask. Funding from Center for Hierarchical Manufacturing (CHM); Facility support from Materials Research Science and Engineering Center at UMass Amherst and Cornell High Energy Synchrotron Source

  10. Mechanism of co-nanoprecipitation of organic actives and block copolymers in a microfluidic environment.

    PubMed

    Capretto, Lorenzo; Cheng, Wei; Carugo, Dario; Katsamenis, Orestis L; Hill, Martyn; Zhang, Xunli

    2012-09-21

    Microreactors have been shown to be a powerful tool for the production of nanoparticles (NPs); however, there is still a lack of understanding of the role that the microfluidic environment plays in directing the nanoprecipitation process. Here we investigate the mechanism of nanoprecipitation of block copolymer stabilized organic NPs using a microfluidic-based reactor in combination with computational fluid dynamics (CFD) modelling of the microfluidic implementation. The latter also accounts for the complex interplay between molecular and hydrodynamic phenomena during the nanoprecipitation process, in order to understand the hydrodynamics and its influence on the NP formation process. It is demonstrated that the competitive reactions result in the formation of two types of NPs, i.e., either with or without loading organic actives. The obtained results are interpreted by taking into consideration a new parameter representing the mismatching between the aggregations of the polymers and actives, which plays a decisive role in determining the size and polydispersity of the prepared hybrid NPs. These results expand the current understanding of the co-nanoprecipitation mechanism of active and block copolymer stabilizer, and on the role exerted by the microfluidic environment, giving information that could be translated to the emerging fields of microfluidic formation of NPs and nanomedicine. PMID:22922560

  11. Tuning Ordered Pattern of Pd Species through Controlled Block Copolymer Self-Assembly.

    PubMed

    De Rosa, Claudio; Auriemma, Finizia; Malafronte, Anna; Di Girolamo, Rocco; Lazzari, Massimo; Nieto-Suárez, Marina; Hermida-Merino, Daniel; Hamley, Ian William; Portale, Giuseppe

    2016-07-14

    We report a method for the preparation of ordered patterns of Pd species on a substrate based on the use of polystyrene-block-poly(ethylene oxide) copolymer (PS-b-PEO) templates and selective inclusion of palladium (Pd) species in the PEO domains. PS-b-PEO samples of different total molecular masses self-assemble in a cylindrical microphase-separated morphology, in which vertically aligned PEO cylinders, with different diameters depending on the molecular mass, are organized in a hexagonal array of different lateral spacings. The cylindrical nanostructure is maintained after the selective inclusion of Pd species (Pd acetate and Pd nanoparticles (NPs) after reduction of Pd ions of the salt) in the PEO cylinders so that the characteristic sizes (diameters and lateral spacings) of the included Pd species are tuned by the characteristic sizes of the block copolymer (BCP) template, which are regulated by molecular mass. Treatment of nanocomposites at elevated temperatures in air removes the polymer matrix and leads to the formation of arrays of palladium oxide (PdO) NPs covering a solid support. The patterns of PdO NPs are characterized by different particle diameters and gap distances, mirroring the patterns and characteristic nanodimensions of the parent BCPs used as templates. PMID:27286502

  12. Novel Injectable Pentablock Copolymer Based Thermoresponsive Hydrogels for Sustained Release Vaccines.

    PubMed

    Bobbala, Sharan; Tamboli, Viral; McDowell, Arlene; Mitra, Ashim K; Hook, Sarah

    2016-01-01

    The need for multiple vaccinations to enhance the immunogenicity of subunit vaccines may be reduced by delivering the vaccine over an extended period of time. Here, we report two novel injectable pentablock copolymer based thermoresponsive hydrogels made of polyethyleneglycol-polycaprolactone-polylactide-polycaprolactone-polyethyleneglycol (PEG-PCL-PLA-PCL-PEG) with varying ratios of polycaprolactone (PCL) and polylactide (PLA), as single shot sustained release vaccines. Pentablock copolymer hydrogels were loaded with vaccine-encapsulated poly lactic-co-glycolic acid nanoparticles (PLGA-NP) or with the soluble vaccine components. Incorporation of PLGA-NP into the thermoresponsive hydrogels increased the complex viscosity of the gels, lowered the gelation temperature, and minimized the burst release of antigen and adjuvants. The two pentablock hydrogels stimulated both cellular and humoral responses. The addition of PLGA-NP to the hydrogels sustained immune responses for up to 49 days. The polymer with a higher ratio of PCL to PLA formed a more rigid gel, induced stronger immune responses, and stimulated effective anti-tumor responses in a prophylactic melanoma tumor model. PMID:26589309

  13. The effects of poly(zwitterions)s versus poly(ethylene glycol) surface coatings on the biodistribution of protein nanoparticles.

    PubMed

    Wang, Jing; Yuan, Shanmei; Zhang, Yajun; Wu, Wei; Hu, Yong; Jiang, Xiqun

    2016-08-16

    Zwitterionic poly(carboxybetaine) (PCB), poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and non-ionic poly(ethylene glycol) (PEG), which have similar degrees of polymerization, were grafted to branched polyethyleneimine (PEI) to generate PCB-grafted PEI (PEI-PCB), PMPC-grafted PEI (PEI-PMPC) and PEG-grafted PEI (PEI-PEG) copolymers, respectively. These grafted PEI copolymers with almost the same grafting number were coated on the surface of 110 nm bovine serum albumin-poly(N-3-acrylamidophenylboronic acid) (BSA-PAPBA) nanoparticles to make a comparison of the surface decoration effect on the biodistribution of nanoparticles. Compared to the nanoparticles without surface decoration, surface decoration with the copolymers significantly prolonged the circulation time of BSA-PAPBA nanoparticles, leading to remarkable enhancement of tumor uptake of the nanoparticles. The drug accumulation at the tumor site reached more than 10% injected dose per gram of tumor. Among them, the PEI-PMPC-decorated nanoparticles exhibited the best performance in tumor accumulation and anticancer ability. Thus, these surface-decorated nanoparticles may serve as a strong candidate for high tumor accumulation of drug delivery systems. PMID:27426309

  14. Combinatorial Block Copolymer Ordering on Tunable Rough Substrates

    SciTech Connect

    Kulkarni, Manish M.; Yager, Kevin G.; Sharma, Ashutosh; Karim, Alamgir

    2012-10-25

    Morphology control of block copolymer (BCP) thin films through substrate interaction via controlled roughness parameters is of significant interest for numerous high-tech applications ranging from solar cells to high-density storage media. While effects of substrate surface energy (SE) and roughness (R) on BCP morphology have been individually investigated, their synergistic effects have not been explored in any systematic manner. Interestingly, orientation response of BCP to changes in SE can be similar to what can be accomplished with variations in R. Here we present a novel approach for orienting lamellar BCP films of poly(styrene)-block-poly(methyl methacrylate) (PS-PMMA) on spin-coated xerogel (a dried gel of silica nanoparticle network) substrate with simultaneously tunable surface energy, {gamma}{sub s} {approx} 29-53 mJ/m{sup 2}, by UVO exposure and roughness, R{sub rms} {approx} 0.5-30 nm, by sol-gel processing steps of regulating the catalyst concentration and sol aging time. As in previous BCP orientation studies on 20 nm diameter monodisperse silica nanoparticle coated surface, we find a similar but broadened oscillatory BCP orientation behavior with film thickness due to the random rather than periodic rough surfaces. We also find that higher random roughness amplitude is not the necessary criteria for obtaining a vertical orientation of BCP lamellae. Rather, a high surface fractal dimension (D{sub f} > 2.4) of the rough substrate in conjunction with an optimal substrate surface energy {gamma}{sub s} {approx} 29 mJ/m{sup 2} results in 100% vertically oriented lamellar microdomains. The AFM measured film surface microstructure correlates well with the internal 3D BCP film structure probed by grazing incidence small-angle X-ray scattering (GISAXS) and rotational small-angle neutron scattering (SANS). In contrast to tunable self-assembled monolayer (SAM)-coated substrates, the xerogel films are very durable and retain their chemical properties over period

  15. Aqueous self-assembly of poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) copolymers: disparate diblock copolymer compositions give rise to nano- and meso-scale bilayered vesicles

    NASA Astrophysics Data System (ADS)

    Qi, Wei; Ghoroghchian, P. Peter; Li, Guizhi; Hammer, Daniel A.; Therien, Michael J.

    2013-10-01

    Nanoparticles formed from diblock copolymers of FDA approved PEO and PCL have generated considerable interest as in vivo drug delivery vehicles. Herein, we report the synthesis of the most extensive family PEO-b-PCL copolymers that vary over the largest range of number-average molecular weights (Mn: 3.6-57k), PEO weight fractions (fPEO: 0.08-0.33), and PEO chain lengths (0.75-5.8k) reported to date. These polymers were synthesized in order to establish the full range of aqueous phase behaviours of these diblock copolymers and to specifically identify formulations that were able to generate bilayered vesicles (polymersomes). Cryogenic transmission electron microscopy (cryo-TEM) was utilized in order to visualize the morphology of these structures upon aqueous self-assembly of dry polymer films. Nanoscale polymersomes were formed from PEO-b-PCL copolymers over a wide range of PEO weight fractions (fPEO: 0.14-0.27) and PEO molecular weights (0.75-3.8k) after extrusion of aqueous suspensions. Comparative morphology diagrams, which describe the nature of self-assembled structures as a function of diblock copolymer molecular weight and PEO weight fraction, show that in contrast to micron-scale polymersomes, which form only from a limited range of PEO-b-PCL diblock copolymer compositions, a multiplicity of PEO-b-PCL diblock copolymer compositions are able to give rise to nanoscale vesicles. These data underscore that PEO-b-PCL compositions that spontaneously form micron-sized polymersomes, as well as those that have previously been reported to form polymersomes via a cosolvent fabrication system, provide only limited insights into the distribution of PEO-b-PCL diblocks that give rise to nanoscale vesicles. The broad range of polymersome-forming PEO-b-PCL compositions described herein suggest the ability to construct extensive families of nanoscale vesicles of varied bilayer thickness, providing the ability to tune the timescales of vesicle degradation and encapsulant

  16. Red Blood Cell Membrane-Cloaked Nanoparticles For Drug Delivery

    NASA Astrophysics Data System (ADS)

    Carpenter, Cody Westcott

    Herein we describe the development of the Red Blood Cell coated nanoparticle, RBC-NP. Purified natural erythrocyte membrane is used to coat drug-loaded poly(lacticco-glycolic acid) (PLGA). Synthetic PLGA co-polymer is biocompatible and biodegradable and has already received US FDA approval for drug-delivery and diagnostics. This work looks specifically at the retention of immunosuppressive proteins on RBC-NPs, right-sidedness of natural RBC membranes interfacing with synthetic polymer nanoparticles, sustained and retarded drug release of RBC-NPs as well as further surface modification of RBC-NPs for increased targeting of model cancer cell lines.

  17. Bimetallic nanoparticles: Preparation, properties, and biomedical applications.

    PubMed

    Nasrabadi, Hamid Tayefi; Abbasi, Elham; Davaran, Soodabeh; Kouhi, Mohammad; Akbarzadeh, Abolfazl

    2016-01-01

    Many studies of non-supported bimetallic nanoparticle (BMNP) dispersions, stabilized by ligands or polymers, and copolymers, were started only about 10 years ago. Several preparative procedures have been proposed, and full characterizations on BMNPs have been approved. Studies on BMNPs received huge attention from both scientific and technological communities because most of the NPs' catalytic activity depends on their structural aspects. In this study, we focus on the preparation, properties, and bio-application of BMNPs and introduction of the recent advance in these NPs. PMID:25203939

  18. Self-Assembly of Pluronic Block Copolymers in Solutions: Simulation and Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Zhang, Zhe; Hong, Kunlun; Do, Changwoo; Biology and Soft-Matter Division, Oak Ridge National Laboratory Team; Chemical Science Division, Oak Ridge National Laboratory Team

    2014-03-01

    Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers in water solution display various phase behaviors such as micellar, lamellar, and hexagonal phases and have been of great interest to researchers for their wide range of applications including templates of various nanostructures in solar cell and transportation of nanoparticles in drug delivery. In this study, we combined density functional theory-based mesoscale simulation and small-angle neutron scattering (SANS) experiments to investigate equilibrium structures of L62/water systems at different concentrations. Various simulation parameters found in the literature have been revisited with the experimental findings. Scattering experiments were found to be an excellent. This research is supported by the U.S. Department of Energy, Basic Energy Sciences, Materials Sciences and Energy Division.

  19. Biomimetic block copolymer particles with gated nanopores and ultrahigh protein sorption capacity

    NASA Astrophysics Data System (ADS)

    Yu, Haizhou; Qiu, Xiaoyan; Nunes, Suzana P.; Peinemann, Klaus-Viktor

    2014-06-01

    The design of micro- or nanoparticles that can encapsulate sensitive molecules such as drugs, hormones, proteins or peptides is of increasing importance for applications in biotechnology and medicine. Examples are micelles, liposomes and vesicles. The tiny and, in most cases, hollow spheres are used as vehicles for transport and controlled administration of pharmaceutical drugs or nutrients. Here we report a simple strategy to fabricate microspheres by block copolymer self-assembly. The microsphere particles have monodispersed nanopores that can act as pH-responsive gates. They contain a highly porous internal structure, which is analogous to the Schwarz P structure. The internal porosity of the particles contributes to their high sorption capacity and sustained release behaviour. We successfully separated similarly sized proteins using these particles. The ease of particle fabrication by macrophase separation and self-assembly, and the robustness of the particles makes them ideal for sorption, separation, transport and sustained delivery of pharmaceutical substances.

  20. Single step synthesis and organization of gold colloids assisted by copolymer templates

    NASA Astrophysics Data System (ADS)

    Sarrazin, Aurélien; Gontier, Arthur; Plaud, Alexandre; Béal, Jérémie; Yockell-Lelièvre, Hélène; Bijeon, Jean-Louis; Plain, Jérôme; Adam, Pierre-Michel; Maurer, Thomas

    2014-06-01

    We report here an original single-step process for the synthesis and self-organization of gold colloids by simply incorporating gold salts into a solution prepared using polystyrene (PS)-polymethylmethacrylate copolymer and thiolated PS with propylene glycol methyl ether acetate as a solvent. The spin-coating and annealing of this solution then allows the formation of PS domains. Depending on the polymer concentration of the as-prepared solution, there can be either one or several gold nanoparticles (Au NPs) per PS domain. For high concentrations of Au NPs in PS domains, the coupling between plasmonic NPs leads to the observation of a second peak in the optical extinction spectrum. Such a collective effect could be relevant for the development of optical strain sensors in the near future.