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Sample records for amphiphilic poly caprolactone-b-polyacrylic

  1. Gold Nanoparticles Protected with Thiol-Derivatized Amphiphilic Poly(epsilon-caprolactone)-b-poly(acrylic acid)

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Hvilsted, Søren

    2009-01-01

    Amphiphilic poly(epsilon-caprolactone)-b-poly(acrylic acid) (HS-PCL-b-PAA) with a thiol functionality in the PCL terminal has been prepared in a novel synthetic cascade. Initially, living anionic ring-opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL) employing the difunctional...

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

    Science.gov (United States)

    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 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.

  3. Sustained release of protein from poly(ethylene glycol) incorporated amphiphilic comb like polymers.

    Science.gov (United States)

    Srividhya, M; Preethi, S; Gnanamani, A; Reddy, B S R

    2006-12-01

    Amphiphilic comb like macromonomer containing hydrophilic poly(ethylene glycol) groups covalently linked to poly(hydromethyl siloxane) (PHMS) were prepared by hydrosilylation reaction. The epoxy reacting sites were introduced to this amphiphilic system by the reaction with allyl epoxy propyl ether (AEPE). Bovine serum albumin (BSA), a model protein drug was loaded to the PEG-PDMS system and very thin membranes were made from this macromonomer adopting solution casting technique. The in vitro protein release studies at various pH conditions showed a controlled release profile without exhibiting any initial burst. The control of the initial burst might be due to the strong linkages of the protein with the membrane and the aggregation of the protein at the surface. The morphology of the membrane before and after the protein release, and the mechanical strength were evaluated. The surface properties of the membrane were studied using the contact angle measurements. PMID:16930885

  4. Syntheses of amphiphilic biodegradable copolymers of poly(ethyl ethylene phosphate) and poly(3-hydroxybutyrate) for drug delivery

    Institute of Scientific and Technical Information of China (English)

    CHENG Jing; WANG Jun

    2009-01-01

    Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (PEEP-b-PHB-b-PEEP) have been successfully synthesized through ring-opening polymerization.The structures are confirmed by gel permeation chromatography and NMR analyses.Crystallization investigated by X-ray diffraction reveals that the block copolymer with higher content of poly(ethyl ethylene phosphate) (PEEP) is more amorphous,showing decreased crystallizability.The obtained copolymers self-assemble into biodegradable nanoparticles with a coreshell micellar structure in aqueous solution,verified by the probe-based fluorescence measurements and transmission electronic microscopy (TEM) observation.The hydrophobic poly(3-hydroxybutyrate) (PHB) block serves as the core of the micelles and the micelles are stabilized by the hydrophilic PEEP block.The size and size distribution are related to the compositions of the copolymers.Paclitaxel (PTX) has been encapsulated into the micelles as a model drug and a sustained drug release from the micelles is observed.MTT assay also demonstrates that the block copolymers are biocompatible,rendering these copolymers attractive for drug delivery.

  5. Syntheses of amphiphilic biodegradable copolymers of poly(ethyl ethylene phosphate) and poly(3-hydroxybutyrate) for drug delivery

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (PEEP-b-PHB-b-PEEP) have been successfully synthesized through ring-opening polymerization. The structures are confirmed by gel permeation chromatography and NMR analyses. Crystallization investigated by X-ray diffraction reveals that the block copolymer with higher content of poly(ethyl ethylene phosphate) (PEEP) is more amorphous, showing decreased crystallizability. The obtained copolymers self-assemble into biodegradable nanoparticles with a coreshell micellar structure in aqueous solution, verified by the probe-based fluorescence measurements and transmission electronic microscopy (TEM) observation. The hydrophobic poly(3-hydroxybutyrate) (PHB) block serves as the core of the micelles and the micelles are stabilized by the hydrophilic PEEP block. The size and size distribution are related to the compositions of the copolymers. Paclitaxel (PTX) has been encapsulated into the micelles as a model drug and a sustained drug release from the micelles is observed. MTT assay also demonstrates that the block copolymers are biocompatible, rendering these copolymers attractive for drug delivery.

  6. Novel 4-Arm Poly(Ethylene Glycol)-Block-Poly(Anhydride-Esters) Amphiphilic Copolymer Micelles Loading Curcumin: Preparation, Characterization, and In Vitro Evaluation

    OpenAIRE

    Li Lv; Yuanyuan Shen; Min Li; Xiaofen Xu; Mingna Li; Shengrong Guo; Shengtang Huang

    2013-01-01

    A novel 4-arm poly(ethylene glycol)-block-poly(anhydride-esters) amphiphilic copolymer (4-arm PEG-b-PAE) was synthesized by esterization of 4-arm poly(ethylene glycol) and poly(anhydride-esters) which was obtained by melt polycondensation of α -, ω -acetic anhydride terminated poly(L-lactic acid). The obtained 4-arm PEG-b-PAE was characterized by 1H-NMR and gel permeation chromatography. The critical micelle concentration of 4-arm PEG-b-PAE was 2.38  μ g/mL. The curcumin-loaded 4-arm PEG-b-PA...

  7. Preparation of poly (acrylic acid)-modified chitosan amphiphilic gels by γ-rays irradiation

    International Nuclear Information System (INIS)

    Poly (acrylic acid)-modified chitosan amphiphilic gels were prepared via O-maleoyl-N-phthaloyl- chitosan as an intermediate by grafting with poly (acrylic acid). The reaction was carried out in a homogeneous sys- tem by γ-ray irradiation. Evidence of grafting was obtained from FTIR spectroscopy. The effects for grafting reaction were investigated systematically. Results show that the grafting degree depends on monomer concentration and ab- sorbed dose. The swelling behavior of chitosan samples with different grafting degree was studied in different buffers as a function of pH. It can be found that all the samples swollen slightly at low pH but very well at high pH. More- over, the swelling behavior of chitosan samples in DMF has been evaluated. (authors)

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

    Directory of Open Access Journals (Sweden)

    Zhao ZM

    2014-12-01

    Full Text Available Ziming Zhao,1,2,* Yu Wang,1,2,* Jin Han,1,2 Keli Wang,1 Dan Yang,1,2 Yihua Yang,1,2 Qian Du,1,2 Yuanjian Song,3 Xiaoxing Yin1,2 1Department of Pharmacy, 2Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, 3Department of Basic Medical Sciences, Xuzhou Medical College, Xuzhou, People’s Republic of China *These authors contributed equally to this work Abstract: The aim of this work was to design, synthesize, and characterize self-assembled micelles based on polypeptides as a potential antitumor drug carrier. Amphiphilic poly(L-phenylalanine-b-poly(L-serine (PFS polypeptides were obtained through the polymerization of N-carboxyanhydride. As a novel hydrophilic segment, poly(L-serine was utilized to enhance tumor targeting due to a large demand of tumors for serine. PFS could self-assemble into micelles with an average diameter of 110–240 nm and a slightly negative charge. PFS polypeptides adopted random coil in pH 7.4 phosphate-buffered saline and could partly transform to a-helix induced by trifluoroethanol. PFS micelles with a low critical micelle concentration of 4.0 µg mL-1 were stable in pH 5–9 buffers and serum albumin solution. PFS micelles had a loading capacity of 3.8% for coumarin-6 and exhibited a sustained drug release. Coumarin-6 loaded rhodamine B isothiocyanate-labeled PFS micelles were incubated with Huh-7 tumor cells to study the correlation between drugs and carriers during endocytosis. The uptake of drugs was consistent with the micelles, illustrating that the intracellular transport of drugs highly depended on the micelles. PFS micelles diffused in whole cytoplasm while coumarin-6 assumed localized distribution, suggesting that the micelles could release the loaded drugs in particular areas. The internalization mechanism of PFS micelles was involved with clathrin-mediated endocytosis and macropinocytosis. Excess serine inhibited the uptake of PFS micelles, which demonstrated that serine receptors played

  9. Structure-property relationship in cytotoxicity and cell uptake of poly(2-oxazoline) amphiphiles

    KAUST Repository

    Luxenhofer, Robert

    2011-07-01

    The family of poly(2-oxazoline)s (POx) is being increasingly investigated in the context of biomedical applications. We tested the relative cytotoxicity of POx and were able to confirm that these polymers are typically not cytotoxic even at high concentrations. Furthermore, we report structure-uptake relationships of a series of amphiphilic POx block copolymers that have different architectures, molar mass and chain termini. The rate of endocytosis can be fine-tuned over a broad range by changing the polymer structure. The cellular uptake increases with the hydrophobic character of the polymers and is observed even at nanomolar concentrations. Considering the structural versatility of this class of polymers, the relative ease of preparation and their stability underlines the potential of POx as a promising platform candidate for the preparation of next-generation polymer therapeutics.

  10. Amphiphilic graft copolymer based on poly(styrene-co-maleic anhydride) with low molecular weight polyethylenimine for efficient gene delivery

    OpenAIRE

    Duan XP; Xiao JS; Yin Q; Zhang ZW; Mao SR; Li YP

    2012-01-01

    Xiaopin Duan,1,2 Jisheng Xiao,2 Qi Yin,2 Zhiwen Zhang,2 Shirui Mao,1 Yaping Li21School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, 2Center of Pharmaceutics, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, ChinaBackground and methods: A new amphiphilic comb-shaped copolymer (SP) was synthesized by conjugating poly(styrene-co-maleic anhydride) with low molecular weight polyethyleneimine for gene delivery. Fourier transform infrared spectrum, 1H nuclea...

  11. Self-assembled amphiphilic polyhedral oligosilsesquioxane (POSS) grafted poly(vinyl alcohol) (PVA) nanoparticles

    International Nuclear Information System (INIS)

    In the present study, spherical nanoparticles (NPs) containing polyhedral oligosilsesquioxane (POSS) as an inner hydrophobic core and poly(vinyl alcohol) PVA as a hydrophilic outer shell were prepared by dialysis approach. Preparation of amphiphilic POSS-grafted-PVA co-polymer was characterized by 1H NMR and FT-IR. The results indicated urethane linkage between monoisocyanate group of POSS macromer and the hydroxyl groups of PVA. The dynamic light scattering (DLS) and electrophoretic light scattering (ELS) of the NPs revealed that they have an average hydrodynamic diameter and negative zeta (ζ)-potential of 215 nm and - 161 mV, respectively. Atomic force microscopy (AFM) and bio-transmission electron microscope (BIO-TEM) have shown unagglomerated NPs within a diameter range of 60-90 nm. The prepared NPs were investigated to improve the control release of anticancer drug; paclitaxel as a model drug. Due to drug loading, the hydrodynamic diameter and negative zeta (ζ)-potential have changed to 325 nm and - 14 mV, respectively. In addition, in-vitro drug release experiments were conducted; the obtained results explicated continuous release for over 40 days. However, in case of using pure drug only, the drug completely released within 1 h.

  12. Synthesis, Micellization and Characterization of Novel Amphiphilic β-Cyclodextrin/Poly(L-aspartate) Copolymer

    Institute of Scientific and Technical Information of China (English)

    GUO Yan-ling; CUI Zhao-shan; HAN Min

    2013-01-01

    A novel amphiphilic β-cyclodextrin/poly(L-aspartate)(β-CD-PASP) copolymer was prepared by ringopening polymerization of polysuccinimide(PSI).This copolymer bears β-CD units along the macromolecular chain and the structure was characterized by infrared(IR) and proton nuclear magnetic resonance(1H NMR).The molecular weight of the copolymer was determined by gel permeation chromatography(GPC).The copolymer micelle were prepared by direct dissolution method.The critical micelle concentration(CMC) of the copolymer micelle was measured by flourescence technique with pyrene as probe.The size distribution of micelle was characterized on a dynamic laser light scattering particle size analyzer and its shape was observed by transmission electron microscopy(TEM).The results show that the copolymer could self-assemble into micelle with a low CMC,and the effective diameter of the micelle was 116.3 nm.The methotrexate(MTX)-loaded micelle were prepared and the drug loading content(DLC) was 22.86%.The MTX-loaded copolymer exhibited a better water-solubility than the free drug.

  13. Ultralow Oil-Fouling Heterogeneous Poly(ether sulfone) Ultrafiltration Membrane via Blending with Novel Amphiphilic Fluorinated Gradient Copolymers.

    Science.gov (United States)

    Zhang, Guangfa; Jiang, Jingxian; Zhang, Qinghua; Gao, Fan; Zhan, Xiaoli; Chen, Fengqiu

    2016-02-01

    A novel amphiphilic fluorinated gradient copolymer was prepared by semibatch reversible addition-fragmentation chain transfer (RAFT) method using poly(ethylene glycol) methyl ether methacrylate (PEGMA) and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate (TFOA) as monomers. The resultant amphiphilic copolymers were then incorporated into the poly(ether sulfone) (PES) to fabricate PES blend membranes via the non-solvent-induced phase separation method (NIPS). During the phase inversion process, both hydrophilic (PEGMA) and low surface energy (TFOA) segments significantly enriched on the membrane surface by surface segregation to form an amphiphilic surface, which was demonstrated by surface wetting properties and X-ray photoelectron spectroscopy (XPS) measurements. According to the filtration experiments of oil-in-water emulsion, the heterogeneous membranes exhibited superior oil-fouling resistant properties, that is, low flux decay (as low as 15.4%) and high flux recovery (almost 100%), compared to the pure PES membrane. The synergistic effect of fouling-resistant and fouling-release mechanisms was found to be responsible for the excellent antifouling capacities. The findings of this study offer a facile and robust strategy for fabricating ultralow oil-fouling membranes that might be used for effective oil/water separation. PMID:26780307

  14. Synthesis and self-assembly of amphiphilic poly(acrylicacid)-poly(ɛ-caprolactone)-poly(acrylicacid) block copolymer as novel carrier for 7-ethyl-10-hydroxy camptothecin.

    Science.gov (United States)

    Djurdjic, Beti; Dimchevska, Simona; Geskovski, Nikola; Petrusevska, Marija; Gancheva, Valerya; Georgiev, Georgi; Petrov, Petar; Goracinova, Katerina

    2015-01-01

    The process of molecular self-assembly plays a crucial role in formulation of polymeric nanoparticulated drug delivery carriers as it creates the possibility for enhanced drug encapsulation and carrier surface engineering. This study aimed to develop a novel self-assembled polymeric micelles for targeted delivery in tumor cells in order to overcome not only various drawbacks of 7-ethyl-10-hydroxy camptothecin (SN-38) but also various reported limitations of other drug delivery systems, especially low drug loading and premature release. Custom synthesized amphiphilic triblock copolymer poly(acrylic acid)-poly(ɛ-caprolactone)-poly(acrylic acid) (PAA(13)-PCL(35)-PAA(13)) was used to prepare kinetically stable micelles by nanoprecipitation and modified nanoprecipitation procedure. Core-shell micelles with diameter of 120-140 nm, negative zeta potential and satisfactory drug loading were produced. The prepared formulations were stable in pH range of 3-12 and in media with NaCl concentration <1 mol/l. Screening mixed level factorial 3 × 2(2) design identified that the process temperature as well as the type of organic solvent has influence upon the efficacy of encapsulation, particle size, dissolution rate and burst release. Fourier transform infrared and differential scanning calorimetry analyses confirmed the entrapment of the active substance into the micelles. The kinetic analysis of dissolution studies revealed that the main mechanism of drug release from the prepared formulations is Fickian diffusion. Growth inhibition studies as well as DNA fragmentation assay performed on SW-480 cell lines clearly demonstrated increased growth inhibition effect and presence of fragmented DNA in cells treated with loaded micelles compared to SN-38 solution. Altogether, these results point out to potential biomedical and clinical application of PAA-PCL-PAA systems in the future.

  15. Thermo-Responsive Polyurethane Hydrogels Based on Poly(ε-caprolactone Diol and Amphiphilic Polylactide-Poly(Ethylene Glycol Block Copolymers

    Directory of Open Access Journals (Sweden)

    Shan-hui Hsu

    2016-07-01

    Full Text Available Waterborne polyurethane (PU based on poly(ε-caprolactone (PCL diol and an amphiphilic polylactide-poly(ethylene glycol (PLA-PEG diblock copolymer was synthesized. The molar ratio of PCL/PLA-PEG was 9:1 with different PLA chain lengths. The PU nanoparticles were characterized by dynamic light scattering (DLS, small angle X-ray scattering (SAXS and rheological analysis. The water contact angle measurement, infrared spectroscopy, wide angle X-ray scattering (WAXS, thermal and mechanical analyses were conducted on PU films. Significant changes in physio-chemical properties were observed for PUs containing 10 mol % of amphiphilic blocks. The water contact angle was reduced to 12°–13°, and the degree of crystallinity was 5%–10%. The PU dispersions underwent sol-gel transition upon the temperature rise to 37 °C. The gelation time increased as the PLA chain length increased. In addition, the fractal dimension of each gel was close to that of a percolation cluster. Moreover, PU4 with a solid content of 26% could support the proliferation of human mesenchymal stem cells (hMSCs. Therefore, thermo-responsive hydrogels with tunable properties are promising injectable materials for cell or drug delivery.

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

    OpenAIRE

    Dong, Anjie

    2009-01-01

    Jinfeng Xing, Liandong Deng, Jun Li, Anjie DongDepartment of Polymer Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, People’s Republic of ChinaAbstract: 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 b...

  17. Polystyrene-Poly(sodium methacrylate) Amphiphilic Block Copolymers by ATRP : Effect of Structure, pH, and Ionic Strength on Rheology of Aqueous Solutions

    NARCIS (Netherlands)

    Raffa, Patrizio; Brandenburg, Piter; Wever, Diego A. Z.; Broekhuis, Antonius A.; Picchioni, Francesco

    2013-01-01

    Three well-defined polystyrene-poly(sodium methacrylate) amphiphilic block copolymers characterized by different molecular architecture (diblock, triblock, and four-arm star) have been synthesized by ATRP. The rheology of their water solutions has been evaluated by measuring dynamic moduli and shear

  18. Amphiphilic poly(D- or L-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) block copolymers: controlled synthesis, characterization, and stereocomplex formation.

    Science.gov (United States)

    Spasova, Mariya; Mespouille, Laetitia; Coulembier, Olivier; Paneva, Dilyana; Manolova, Nevena; Rashkov, Iliya; Dubois, Philippe

    2009-05-11

    Novel well-defined amphiphilic poly(D-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) (PDLA-b-PDMAEMA) and poly(L-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) (PLLA-b-PDMAEMA) copolymers were obtained. The synthesis strategy consisted of a three-step procedure: (i) controlled ring-opening polymerization (ROP) of (D- or L-)lactide initiated by Al(O(i)Pr)(3), followed by (ii) quantitative conversion of the polylactide (PLA) hydroxyl end-groups with bromoisobutyryl bromide and (iii) atom transfer radical polymerization (ATRP) of DMAEMA. The PLA block molecular weight was kept below 5000 g/mol. The macromolecular parameters of the (co)polymers were determined by (1)H NMR spectroscopy and size exclusion chromatography (SEC). The stereocomplexes of PDLA-b-PDMAEMA/PLLA-b-PDMAEMA diblock copolymers were prepared via solvent casting. The stereocomplex formation was evidenced by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses. The obtained stereocomplexes had melting temperature of about 65 degrees C above that of the individual copolymers and exhibited diffraction patterns assigned to the stereocomplex crystallites. In addition, for the first time it was shown that the replacement of one of the PLA partners with high molecular weight PLLA or PDLA did not hamper the stereocomplex formation. The presence of PDMAEMA blocks proved to impart hydrophilicity of the synthesized copolymers and related stereocomplexes, as determined by static water contact angle measurements. PMID:19331403

  19. Synthesis of Amphiphilic Poly(2-(1-Pyrrolidonyl)-Ethylvinylether-b-Isobutylvinylether)

    NARCIS (Netherlands)

    Nuyken, O.; Rieß, G.; Loontjens, J.A.; Linde, R. van der

    1995-01-01

    Block copolymers consisting of isobutyl vinylether (IBVE) and 2-(1-pyrrolidonyl)-ethylvinylether (PEVE) were synthesized by the nucleophilic substitution of poly(2-chloroethylvinylether-b-isobutylvinylether) (poly(CEVE-b-IBVE)) by the anion of pyrrolidone. The poly(CEVE-b-IBVE) was obtained by seque

  20. Novel 4-Arm Poly(Ethylene Glycol-Block-Poly(Anhydride-Esters Amphiphilic Copolymer Micelles Loading Curcumin: Preparation, Characterization, and In Vitro Evaluation

    Directory of Open Access Journals (Sweden)

    Li Lv

    2013-01-01

    Full Text Available A novel 4-arm poly(ethylene glycol-block-poly(anhydride-esters amphiphilic copolymer (4-arm PEG-b-PAE was synthesized by esterization of 4-arm poly(ethylene glycol and poly(anhydride-esters which was obtained by melt polycondensation of α-, ω-acetic anhydride terminated poly(L-lactic acid. The obtained 4-arm PEG-b-PAE was characterized by 1H-NMR and gel permeation chromatography. The critical micelle concentration of 4-arm PEG-b-PAE was 2.38 μg/mL. The curcumin-loaded 4-arm PEG-b-PAE micelles were prepared by a solid dispersion method and the drug loading content and encapsulation efficiency of the micelles were 7.0% and 85.2%, respectively. The curcumin-loaded micelles were spherical with a hydrodynamic diameter of 151.9 nm. Curcumin was encapsulated within 4-arm PEG-b-PAE micelles amorphously and released from the micelles, faster in pH 5.0 than pH 7.4, presenting one biphasic drug release pattern with rapid release at the initial stage and slow release later. The hemolysis rate of the curcumin-loaded 4-arm PEG-b-PAE micelles was 3.18%, which was below 5%. The IC50 value of the curcumin-loaded micelles against Hela cells was 10.21 μg/mL, lower than the one of free curcumin (25.90 μg/mL. The cellular uptake of the curcumin-loaded micelles in Hela cell increased in a time-dependent manner. The curcumin-loaded micelles could induce G2/M phase cell cycle arrest and apoptosis of Hela cells.

  1. Effects of amphiphilic chitosan-g-poly(ε-caprolactone) polymer additives on paclitaxel release from drug eluting implants

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Weibin [Department of General Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092 (China); Gu, Chunhua [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Jiang, Han [Department of General Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092 (China); Zhang, Mengru [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Lang, Meidong, E-mail: mdlang@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2014-12-01

    Bioresorbable polymer stents have been proposed as promising medical implants to avoid long-term safety concerns and other potential issues caused by traditional materials. As an important member, poly(ε-caprolactone) (PCL) was used as the implant matrix with different drug loadings. To better regulate drug release rate, the hydrophilicity of PCL was adjusted by addition of amphiphilic graft copolymers, chitosan-g-poly(ε-caprolactone) (CP). The in vitro release results indicated that the improvement of bulk hydrophilicity could accelerate drug release better than that of surface coating. The optimum additive amount was 25% with CP9. Further study showed that the effect of aspirin molecules displayed no obvious difference to that of CP macromolecules on drug release rate. Moreover, these release profiles were fitted with mathematical models. The similarities were evaluated with similarity factors. Scanning electron microscopy (SEM) images displayed surface/cross-section morphologies of pure PCL and modified implants before and after release. - Highlights: • The improvement of bulk hydrophilicity better accelerated drug release. • The higher weight ratio of CP implants had, the faster the drug released. • The shorter PCL chain in CP graft coploymers, the faster the drug released. • The optimum additive amount was 25% with CP9. • Drug release profile conformed to controllable Fick diffusional release mechanism.

  2. Effects of amphiphilic chitosan-g-poly(ε-caprolactone) polymer additives on paclitaxel release from drug eluting implants

    International Nuclear Information System (INIS)

    Bioresorbable polymer stents have been proposed as promising medical implants to avoid long-term safety concerns and other potential issues caused by traditional materials. As an important member, poly(ε-caprolactone) (PCL) was used as the implant matrix with different drug loadings. To better regulate drug release rate, the hydrophilicity of PCL was adjusted by addition of amphiphilic graft copolymers, chitosan-g-poly(ε-caprolactone) (CP). The in vitro release results indicated that the improvement of bulk hydrophilicity could accelerate drug release better than that of surface coating. The optimum additive amount was 25% with CP9. Further study showed that the effect of aspirin molecules displayed no obvious difference to that of CP macromolecules on drug release rate. Moreover, these release profiles were fitted with mathematical models. The similarities were evaluated with similarity factors. Scanning electron microscopy (SEM) images displayed surface/cross-section morphologies of pure PCL and modified implants before and after release. - Highlights: • The improvement of bulk hydrophilicity better accelerated drug release. • The higher weight ratio of CP implants had, the faster the drug released. • The shorter PCL chain in CP graft coploymers, the faster the drug released. • The optimum additive amount was 25% with CP9. • Drug release profile conformed to controllable Fick diffusional release mechanism

  3. Amphiphilic graft copolymer based on poly(styrene-co-maleic anhydride with low molecular weight polyethylenimine for efficient gene delivery

    Directory of Open Access Journals (Sweden)

    Duan XP

    2012-09-01

    Full Text Available Xiaopin Duan,1,2 Jisheng Xiao,2 Qi Yin,2 Zhiwen Zhang,2 Shirui Mao,1 Yaping Li21School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, 2Center of Pharmaceutics, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, ChinaBackground and methods: A new amphiphilic comb-shaped copolymer (SP was synthesized by conjugating poly(styrene-co-maleic anhydride with low molecular weight polyethyleneimine for gene delivery. Fourier transform infrared spectrum, 1H nuclear magnetic resonance, and gel permeation chromatography were used to characterize the graft copolymer.Results: The buffering capability of SP was similar to that of polyethyleneimine within the endosomal pH range. The copolymer could condense DNA effectively to form complexes with a positive charge (13–30 mV and a small particle size (130–200 nm at N/P ratios between 5 and 20, and protect DNA from degradation by DNase I. In addition, SP showed much lower cytotoxicity than polyethyleneimine 25,000. Importantly, the gene transfection activity and cellular uptake of SP-DNA complexes were all markedly higher than that of complexes of polyethyleneimine 25,000 and DNA in MCF-7 and MCF-7/ADR cell lines.Conclusion: This work highlights the promise of SP as a safe and efficient synthetic vector for DNA delivery.Keywords: poly(styrene-co-maleic anhydride, polyethylenimine, DNA, gene delivery

  4. Swelling behaviour of amphiphilic poly (methacryloxyethl dimethylalkane ammonium bromide) gels in alcohol/water solvent systems

    International Nuclear Information System (INIS)

    Three kinds of amphiphilic PMADAB gels were prepared through radiation-induced polymerization and crosslinking of methacryloxyethyl dimethylalkane ammonium bromide (MADAB) with different alkyl side chains (butyl, octyl and dodecyl). The length of alkyl side chains had significant influence on swelling behavior of the PMADAB gels in alcohol/water solvent. Equilibrium swelling degree (EDS) of PMBDAB (butyl) gel in water was ca. 160 and decreased with increasing alcohol content (x), whereas EDS of PMODAB (octyl) and PMDDDAB (dodecyl) gels showed a convex-upward function of x, i.e., these two gels barely swelled in pure water and swelled with increasing x and then shrank gradually. This phenomenon was explained by the hydrophobic association of long alkyl chains and a cosolvency effect of PMADAB in alcohol and water. The swelling behavior of PMADAB gels in methanol, ethanol and isopropanol were similar, and their EDS are related with the dielectric constant of alcohol solvents. The results suggest that PMADAB gels may be potential absorbents for various kinds of alcohols. (authors)

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

    Directory of Open Access Journals (Sweden)

    Jinfeng Xing

    2009-10-01

    Full Text Available Jinfeng Xing, Liandong Deng, Jun Li, Anjie DongDepartment of Polymer Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, People’s Republic of ChinaAbstract: 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. Keywords: poly{[α-maleic anhydride-ω-methoxy-poly(ethylene glycol]-co-(ethyl cyanoacrylate}, nanoparticles, transdermal drug delivery, D,L-tetrahydropalmatine

  6. Poly(dimethyl siloxane) (PDMS) network blends of amphiphilic acrylic copolymers with poly(ethylene glycol)-fluoroalkyl side chains for fouling-release coatings. II. Laboratory assays and field immersion trials.

    Science.gov (United States)

    Martinelli, Elisa; Sarvothaman, Mahesh K; Galli, Giancarlo; Pettitt, Michala E; Callow, Maureen E; Callow, James A; Conlan, Sheelagh L; Clare, Anthony S; Sugiharto, Albert B; Davies, Cait; Williams, David

    2012-01-01

    Amphiphilic copolymers containing different amounts of poly(ethylene glycol)-fluoroalkyl acrylate and polysiloxane methacrylate units were blended with a poly(dimethyl siloxane) (PDMS) matrix in different proportions to investigate the effect of both copolymer composition and loading on the biological performance of the coatings. Laboratory bioassays revealed optimal compositions for the release of sporelings of Ulva linza, and the settlement of cypris larvae of Balanus amphitrite. The best-performing coatings were subjected to field immersion tests. Experimental coatings containing copolymer showed significantly reduced levels of hard fouling compared to the control coatings (PDMS without copolymer), their performance being equivalent to a coating based on Intersleek 700™. XPS analysis showed that only small amounts of fluorine at the coating surface were sufficient for good antifouling/fouling-release properties. AFM analyses of coatings under immersion showed that the presence of a regular surface structure with nanosized domains correlated with biological performance.

  7. Molecular Differentiated Initiator Reactivity in the Synthesis of Poly(caprolactone-Based Hydrophobic Homopolymer and Amphiphilic Core Corona Star Polymers

    Directory of Open Access Journals (Sweden)

    Eileen Deng

    2015-11-01

    Full Text Available Macromolecules that possess three-dimensional, branched molecular structures are of great interest because they exhibit significantly differentiated application performance compared to conventional linear (straight chain polymers. This paper reports the synthesis of 3- and 4-arm star branched polymers via ring opening polymerisation (ROP utilising multi-functional hydroxyl initiators and Sn(Oct2 as precatalyst. The structures produced include mono-functional hydrophobic and multi-functional amphiphilic core corona stars. The characteristics of the synthetic process were shown to be principally dependent upon the physical/dielectric properties of the initiators used. ROP’s using initiators that were more available to become directly involved with the Sn(Oct2 in the “in-situ” formation of the true catalytic species were observed to require shorter reaction times. Use of microwave heating (MWH in homopolymer star synthesis reduced reaction times compared to conventional heating (CH equivalents, this was attributed to an increased rate of “in-situ” catalyst formation. However, in amphiphilic core corona star formation, the MWH polymerisations exhibited slower propagation rates than CH equivalents. This was attributed to macro-structuring within the reaction medium, which reduced the potential for reaction. It was concluded that CH experiments were less affected by this macro-structuring because it was disrupted by the thermal currents/gradients caused by the conductive/convective heating mechanisms. These gradients are much reduced/absent with MWH because it selectively heats specific species simultaneously throughout the entire volume of the reaction medium. These partitioning problems were overcome by introducing additional quantities of the species that had been determined to selectively heat.

  8. Synthesis and self-assembly behavior of amphiphilic diblock copolymer dextran-block-poly(ε-caprolactone (DEX-b-PCL in aqueous media

    Directory of Open Access Journals (Sweden)

    2010-10-01

    Full Text Available An amphiphilic diblock copolymer, dextran-block-poly(ε-caprolactone (DEX-b-PCL, with a series of welldefined chain lengths of each block was prepared by conjugating a dextran chain with a PCL block via aza-Michael addition reaction under mild conditions. For the dextran block, samples with relatively uniform molecular weight, 3.5 and 6.0 kDa, were used, and the PCL blocks were prepared via ring-opening polymerization at defined ratios of ε-caprolactone to initiator in order to give copolymers with mass fraction of dextran (fDEX ranging from 0.16 to 0.45. When these copolymers were allowed to self-assemble in aqueous solution, the morphology of assembled aggregates varied as a function of fDEX when characterized by transmission electron microscope (TEM, fluorescence microscope (FM and dynamic laser scattering (DLS. As fDEX decreases gradually from 0.45 to 0.16, the morphology of the copolymer assembly changes from spherical micelles to worm-like micelles and eventually to polymersomes, together with an increase in particle sizes.

  9. Self-Assembly of Amphiphilic Block Copolymers Containing Poly(n-octadecyl acrylate) Block in Aqueous Solution

    Energy Technology Data Exchange (ETDEWEB)

    Akiba, Isamu; Akino, Yusuke; Masunaga, Hiroyasu; Sakurai, Kazuo, E-mail: akiba@env.kitakyu-u.ac.jp

    2010-11-15

    Synchrotron small-angle X-ray scattering (SAXS) experiments were carried out for poly(acrylic acid)-block-poly(n-octadecyl acrylate) (PAA-b-PODA) and PAA-b-PODA-b-PAA micelles in aqueous solutions. SAXS results indicated that PAA-b-PODA and PAA-b-PODA-b-PAA formed core-shell micelles with disk-like morphology below melting temperature of PODA in aqueous solutions. The thickness of PAA-b-PODA (diblock copolymer) micelle was larger than that of PAA-b-PODA-b-PAA (triblock copolymer) micelle. The difference of sizes between these micelles was related to difference of molecular architectures of PAA-b-PODA and PAA-b-PODA-b-PAA. PAA-b-PODA micelle showed morphological transition from disk to spherical shape with elevating temperature. On the contrary, PAA-b-PODA-b-PAA micelle maintained disk-like shape above melting temperature, although enlargement of micelle thickness is caused.

  10. Self-Assembly of Amphiphilic Block Copolymers Containing Poly(n-octadecyl acrylate) Block in Aqueous Solution

    Science.gov (United States)

    Akiba, Isamu; Akino, Yusuke; Masunaga, Hiroyasu; Sakurai, Kazuo

    2010-11-01

    Synchrotron small-angle X-ray scattering (SAXS) experiments were carried out for poly(acrylic acid)-block-poly(n-octadecyl acrylate) (PAA-b-PODA) and PAA-b-PODA-b-PAA micelles in aqueous solutions. SAXS results indicated that PAA-b-PODA and PAA-b-PODA-b-PAA formed core-shell micelles with disk-like morphology below melting temperature of PODA in aqueous solutions. The thickness of PAA-b-PODA (diblock copolymer) micelle was larger than that of PAA-b-PODA-b-PAA (triblock copolymer) micelle. The difference of sizes between these micelles was related to difference of molecular architectures of PAA-b-PODA and PAA-b-PODA-b-PAA. PAA-b-PODA micelle showed morphological transition from disk to spherical shape with elevating temperature. On the contrary, PAA-b-PODA-b-PAA micelle maintained disk-like shape above melting temperature, although enlargement of micelle thickness is caused.

  11. Synthesis and characterization of a novel amphiphilic biodegradable β-cyclodextrin/poly(γ-benzyl L-glutamate) copolymer

    Institute of Scientific and Technical Information of China (English)

    Qiu Hua Wu; Fang Liang; Tian Zhu Wei; Xi Ming Song; Shu Yao Wu; Guo Lin Zhang

    2009-01-01

    β-Cyclodextrin/poly(γ-benzyl L-glutamate) (β-CD-PBLG) copolymers were synthesized by ring-opening polymerization of N-carboxy-γ-benzyl L-glutamate anhydride (BLG-NCA) in N,N-dimethylformamide (DMF) initiated by mono-amino-β-cyclodex-trin(H2N-β-CD). The structures of the copolymers were confirmed by IR, 1H NMR and GPC. The fluorescence technique was used to determine the critical micelle concentrations (CMC) of copolymer miceU solution, the diameter and the distribution of micelles were characterized by DLS. The results showed that BLG-NCA could be initiated by H2N-β-CD to produce copolymer. The nano-micells were formed by these copolymers in water.

  12. ANTIFOULING PROPERTIES OF POLY(VINYL CHLORIDE) MEMBRANES MODIFIED BY AMPHIPHILIC COPOLYMERS P(MMA-b-MAA)

    Institute of Scientific and Technical Information of China (English)

    Wei-dong Liu; Yong-hua Zhang; Li-feng Fang; Bao-ku Zhu; Li-ping Zhu

    2012-01-01

    Three well-defined diblock copolymers ofpoly(methyl methacrylate-b-methaerylic acid) (P(MMA-b-MAA)) were synthesized using atom transfer radical polymerization method and varying poly(methacrylic acid) (PMAA) chain lengths.These copolymers were blended with PVC to fabricate porous membranes via phase inversion process.Membrane morphologies were observed by scanning electron microscopy (SEM),and chemical composition changes of the membrane surfaces were measured by X-ray photoelectron spectroscopy (XPS).Static and dynamic protein adsorption experiments were used to evaluate antifouling properties of the blend membranes.It was found that,the blend membranes containing longer PMAA arm length showed lower static protein adsorption,higher water permeation flux and better protein solution flux recovery.

  13. Preparation and self-assembly behavior of polystyrene-block-poly (dimethylaminoethyl methacrylate amphiphilic block copolymer using atom transfer radical polymerization

    Directory of Open Access Journals (Sweden)

    2008-03-01

    Full Text Available Asymmetric and semi-symmetric amphiphilic diblock copolymers polystyrene-block-poly (dimethylaminoethyl methacrylate (PS-b-PDMAEMA with the same PS block length of 62 repeat units and quite short (3 repeat units or equivalent (47 repeat units length of PDMAEMA have been prepared simply by varying the ratio of the bromine-terminated macroinitiator polystyrene (PS-Br to DMAEMA using atom transfer radical polymerization (ATRP. The chemical structures and compositions of the PS-b-PDMAEMA block copolymers are studied by nuclear magnetic resonance (NMR spectroscopy, gel permeation chromatography (GPC, and elementary analysis (EA. The self-assembly behaviors of copolymers in N,N-dimethyl formamide (DMF with different pH and dioxane/water binary solvent mixture by direct dissolution method (DD, are studied by transmission electron microscopy (TEM, electron diffracting analysis (EDA, and energy-dispersive analysis of X-rays (EDAX techniques. Transmission electron microscopy results suggest that asymmetric block copolymer PS62-b-PDMAEMA3 (the numbers in the form of footnotes represent repeated units of each monomer in the copolymer can form spherical core-shell micelles, large compound reverse micelles (LCRMs, hexagonal/rhombic phases, reverse hexagonal/rhombic phases, vesicles, reverse vesicles and necklace-like reverse micelles, controlled by common or selective solvent and pH, while most of the aggregates of semi-symmetric PS62-b-PDMAEMA47 are simply spherical, such as spherical core-shell micelles and reverse spherical core-shell micelles, besides hexagonal/rhombic phases. All above structures are controlled by three components of the free energy of aggregation: core-chain stretching, interfacial energy and intercoronal chain interaction.

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

    Directory of Open Access Journals (Sweden)

    Zhou WJ

    2013-09-01

    Full Text Available Wenjun Zhou,1 Yuanyuan Wang,2 Jiuying Jian,2 Shengfang Song1 1Department of Ophthalmology, Yongchuan Hospital, Chongqing Medical University, Chongqing, People’s Republic of China; 2College of Life Science, Chongqing Medical University, Chongqing, People’s Republic of China 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

  15. Synthesis and characterization of a poly(dimethylsiloxane)-poly(ethylene oxide) block copolymer for fabrication of amphiphilic surfaces on microfluidic devices.

    Science.gov (United States)

    Klasner, Scott A; Metto, Eve C; Roman, Gregory T; Culbertson, Christopher T

    2009-09-01

    A poly(dimethylsiloxane)-poly(ethylene oxide) (PDMS-PEO) vinyl terminated block copolymer has been synthesized via a simple hydrosilylation reaction between hydride-terminated PDMS and PEO divinyl ether. This prepolymer can be subsequently cross-linked into an elastomer in a second hydrosilylation reaction involving a methylhydrosiloxane-dimethylsiloxane copolymer, forming a material suitable for the purposes of fabricating microfluidic devices. The presence of the PEO block in the prepolymer chain results in a much more hydrophilic material following cross-linking. The surface water contact angle of the PDMS-PEO material is 65 degrees +/- 3 (n = 6), as opposed to approximately 110 degrees for native PDMS. Droplets of water straddled by air within molded channels of the PDMS-PEO are concave in shape with contact angles where the fluid meets the side walls of 32 degrees +/- 4 (n = 8), while droplets in PDMS microchannels are more convex with contact angles of 95 degrees +/- 6 (n = 6). The length of the PDMS-PEO prepolymer chain and the multifunctional hydride cross-linker chains appear to dictate the durability of the elastomeric material. Young's modulus measurements yielded values of 0.94 +/- 0.08, 2.6 +/- 0.8, and 1.91 +/- 0.06 MPa for a [5% vinyl excess prepolymer and 10-fold excess of cross-linker], [10% vinyl excess prepolymer and 5-fold excess of cross-linker], and 10:1 PDMS, respectively, confirming that the elasticity of the cross-linked PDMS-PEO is similar to that of PDMS (Sylgard 184:10:1 mixture of elastomeric base to elastomer curing agent). The PDMS-PEO material still possesses enough PDMS character to allow molded channel architectures to be sealed between two pieces of the block copolymer by conformal contact. As a result of the more hydrophilic nature of the material, the channels of devices fabricated from this polymer are self-filling when using aqueous buffers, making it more user-friendly than PDMS for applications calling for background

  16. Multifunctional Poly(methyl vinyl ether-co-maleic anhydride)-graft-hydroxypropyl-β-cyclodextrin Amphiphilic Copolymer as an Oral High-Performance Delivery Carrier of Tacrolimus.

    Science.gov (United States)

    Zhang, Dong; Pan, Xiaolei; Wang, Shang; Zhai, Yinglei; Guan, Jibin; Fu, Qiang; Hao, Xiaoli; Qi, Wanpeng; Wang, Yingli; Lian, He; Liu, Xiaohong; Wang, Yongjun; Sun, Yinghua; He, Zhonggui; Sun, Jin

    2015-07-01

    In order to improve oral bioavailability of tacrolimus (FK506), a novel poly(methyl vinyl ether-co-maleic anhydride)-graft-hydroxypropyl-β-cyclodextrin amphiphilic copolymer (CD-PVM/MA) is developed, combining the bioadhesiveness of PVM/MA, P-glycoprotein (P-gp), and cytochrome P450-inhibitory effect of CD into one. The FK506-loaded nanoparticles (CD-PVM/MA-NPs) were obtained by solvent evaporation method. The physiochemical properties and intestinal absorption mechanism of FK506-loaded CD-PVM/MA-NPs were characterized, and the pharmacokinetic behavior was investigated in rats. FK506-loaded CD-PVM/MA-NPs exhibited nanometer-sized particles of 273.7 nm, with encapsulation efficiency as high as 73.3%. FK506-loaded CD-PVM/MA-NPs maintained structural stability in the simulated gastric fluid, and about 80% FK506 was released within 24 h in the simulated intestinal fluid. The permeability of FK506 was improved dramatically by CD-PVM/MA-NPs compared to its solution, probably due to the synergistic inhibition effect of P-gp and cytochrome P450 3A (CYP3A). The intestinal biodistribution of fluorescence-labeled CD-PVM/MA-NPs confirmed its good bioadhesion to the rat intestinal wall. Two endocytosis pathways, clathrin- and caveolae-mediated endocytosis, were involved in the cellular uptake of CD-PVM/MA-NPs. The important role of lymphatic transport in nanoparticles' access to the systemic circulation, about half of the contribution to oral bioavailability, was observed in mesenteric lymph duct ligated rats. The AUC0-24 of FK506 loaded in nanoparticles was enhanced up to 20-fold compared to FK506 solutions after oral administration. The present study suggested that the novel multifunctional CD-PVM/MA is a promising efficient oral delivery carrier for FK506, due to its ability in solubilization, inhibitory effects on both P-gp and CYP 3A, high bioadhesion, and sustained release capability. PMID:26024817

  17. Self-assembly behavior of amphiphilic C₆₀-end-capped poly(vinyl ether)s in water and dissociation of the aggregates by the complexing of the C₆₀ moieties with externally added γ-cyclodextrins.

    Science.gov (United States)

    Motoyanagi, Jin; Kurata, Akihiro; Minoda, Masahiko

    2015-03-01

    C60-end-capped polymers consisting of an amphiphilic poly(2-methoxyethyl vinyl ether) (PMOVE) main chain were synthesized by living cationic polymerization using a C60-functionalized initiator (C60VE-TFA) in the presence of EtAlCl2 as an activator and dioxane as an added base. The obtained polymers (C60-PMOVE) dissolved in a wide range of solvents including water and exhibited solvatochromism depending on the polarity of the media employed. This phenomenon was attributed to self-assembly in polar media due to hydrophobicity of the C60 moieties at the terminus of the amphiphilic polymer chain. Furthermore, the addition of γ-cyclodextrin (γ-CD), a strong host molecule for fullerenes, to the self-assembled system brought about the dissociation of the aggregates into molecularly dispersed free polymer chains. Titration of the aqueous solution of the self-assembly of C60-PMOVE with γ-CD indicated the possible formation of inclusion complexes of C60-PMOVE and γ-CD, and this binding process occurs in a positive cooperative manner. PMID:25658224

  18. Neutral, anionic, cationic, and zwitterionic diblock copolymers featuring poly(2-methoxyethyl acrylate) hydrophobic segments

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Jankova Atanasova, Katja; Hvilsted, Søren

    2013-01-01

    Amphiphilic diblock copolymers incorporating hydrophobic poly(2-methoxyethyl acrylate) (PMEA) and hydrophilic neutral poly(ethylene glycol) monomethyl ether (mPEG), anionic poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA), cationic poly(2-dimethylaminoethyl methacrylate) (PDMAEMA...

  19. Amphiphilic vinyl polymers effectively prolong liposome circulation time in vivo.

    Science.gov (United States)

    Torchilin, V P; Shtilman, M I; Trubetskoy, V S; Whiteman, K; Milstein, A M

    1994-10-12

    Newly synthesized amphiphilic polyacrylamide and poly(vinyl pyrrolidone), single terminus-modified with long-chain fatty acyl groups, are able to incorporate into the liposomal membrane, and similar to poly(ethylene glycol) prolong liposome circulation in vivo and decrease liposome accumulation in the liver. Protective efficacy of modified polymers increases with the increase in the length of acyl moiety and decreases for higher molecular weight polymers. The data on amphiphilic polymer-modified liposome biodistribution are presented.

  20. Synthèse, auto-assemblage et libération contrôlée de principes actifs des nouveaux copolymères à blocs thermo-sensibles et amphiphiles à base de polylactide, de polyacrylamide et de poly(oligo(éthylène glycol) méthacrylate)

    OpenAIRE

    Hu, Yanfei

    2015-01-01

    Deux séries de copolymères tribloc thermo-sensibles et amphiphiles, à savoir poly(L-lactide)/poly(N-isopropylacrylamide-co-N,N-diméthylacrylamide) et poly(L-lactide)/poly(2-(2-méthoxyéthoxy) éthyl méthacrylate-co-oligo(éthylène glycol) méthacrylate) ont été synthétisées par polymérisation radicalaire par transfert d'atomes en utilisant le Br-PLLA-Br comme macroamorceur dans des conditions douces. Les copolymères obtenus présentent une structure de chaînes bien définie avec une dispersité étro...

  1. In vivo pharmacokinetics, biodistribution and antitumor effect of amphiphilic poly(L-amino acids) micelles loaded with a novel all-trans retinoic acid derivative.

    Science.gov (United States)

    Tang, Jihui; Wang, Xinqun; Wang, Ting; Chen, Feihu; Zhou, Jianping

    2014-01-23

    Poly(amino acid)s are well-known as biodegradable and environmentally acceptable materials. In this study, a series of poly(L-aspartic acid)-b-poly(L-phenylalanine) (PAA-PPA) compounds with different degrees of polymerization were used to prepare copolymer micelles for a poorly water-soluble drug 4-amino-2-trifluoromethyl-phenyl retinate (ATPR, a novel all-trans retinoic acid derivative) and in vivo pharmacokinetics, biodistribution and antitumor efficacy of ATPR delivered by PAA-PPA micelles were evaluated. The area under the plasma concentration time curve AUC0→∞ of ATPR-loaded PAA20PPA20 micelles was 2.23 and 1.97 times higher than that of ATPR solution and ATPR CrmEL solution, respectively; In addition, the mean residence time (MRT) was increased 1.67 and 1.97-fold, respectively and the total body clearance (CL) was reduced 2.25 and 1.98-fold, respectively. The biodistribution study indicated that most of the ATPR in the ATPR-M group was distributed in the liver and there was delayed liver aggregation compared with the ATPR solution and ATPR CrmEL solution groups. Furthermore, the antitumor efficacy of ATPR-loaded PAA20PPA20 micelles was demonstrated in in vivo antitumor models involving mice inoculated with the human gastric cancer cell line SGC-7901. At the same dose of 7mg/kg, the ATPR-loaded micelles group demonstrated a better tumor growth inhibition and induced differentiation than the groups given ATPR solution and ATPR CrmEL solution. Therefore, the ATPR-loaded PAA-PPA micelles appear to be a potentially useful drug delivery system for ATPR and suitable for the chemotherapy of gastric cancer.

  2. The role of amphiphiles

    NARCIS (Netherlands)

    Hoekstra, F.A.; Golovina, E.A.

    2002-01-01

    This paper reviews our work on the partitioning of amphiphilic compounds from the cytoplasm into membranes during drying of plant systems, and discusses how relevant this phenomenon might be for anhydrobiosis. Amphiphilic guest molecules do partition into membranes and oil bodies, as demonstrated by

  3. Conjugates of Superoxide Dismutase 1 with Amphiphilic Poly(2-oxazoline) Block Copolymers for Enhanced Brain Delivery: Synthesis, Characterization and Evaluation in Vitro and in Vivo

    KAUST Repository

    Tong, Jing

    2013-01-07

    Superoxide dismutase 1 (SOD1) efficiently catalyzes dismutation of superoxide, but its poor delivery to the target sites in the body, such as brain, hinders its use as a therapeutic agent for superoxide-associated disorders. Here to enhance the delivery of SOD1 across the blood-brain barrier (BBB) and in neurons the enzyme was conjugated with poly(2-oxazoline) (POx) block copolymers, P(MeOx-b-BuOx) or P(EtOx-b-BuOx), composed of (1) hydrophilic 2-methyl-2-oxazoline (MeOx) or 2-ethyl-2-oxazoline (EtOx) and (2) hydrophobic 2-butyl-2-oxazoline (BuOx) repeating units. The conjugates contained from 2 to 3 POx chains joining the protein amino groups via cleavable -(ss)- or noncleavable -(cc)- linkers at the BuOx block terminus. They retained 30% to 50% of initial SOD1 activity, were conformationally and thermally stable, and assembled in 8 or 20 nm aggregates in aqueous solution. They had little if any toxicity to CATH.a neurons and displayed enhanced uptake in these neurons as compared to native or PEGylated SOD1. Of the two conjugates, SOD1-(cc)-P(MeOx-b-BuOx) and SOD1-(cc)-P(EtOx-b-BuOx), compared, the latter was entering cells 4 to 7 times faster and at 6 h colocalized predominantly with endoplasmic reticulum (41 ± 3%) and mitochondria (21 ± 2%). Colocalization with endocytosis markers and pathway inhibition assays suggested that it was internalized through lipid raft/caveolae, also employed by the P(EtOx-b-BuOx) copolymer. The SOD activity in cell lysates and ability to attenuate angiotensin II (Ang II)-induced superoxide in live cells were increased for this conjugate compared to SOD1 and PEG-SOD1. Studies in mice showed that SOD1-POx had ca. 1.75 times longer half-life in blood than native SOD1 (28.4 vs 15.9 min) and after iv administration penetrated the BBB significantly faster than albumin to accumulate in brain parenchyma. The conjugate maintained high stability both in serum and in brain (77% vs 84% at 1 h postinjection). Its amount taken up by the brain

  4. Synthesis of silver nanoparticles in melts of amphiphilic polyesters

    International Nuclear Information System (INIS)

    The current work presents a one-step procedure for the synthesis of amphiphilic silver nanoparticles suitable for production of silver-filled polymeric materials. This solvent free synthesis via reduction of Tollens’ reagent as silver precursor in melts of amphiphilic polyesters consisting of hydrophilic poly(ethylene glycol) blocks and hydrophobic alkyl chains allows the production of silver nanoparticles without any by-product formation. This makes them especially interesting for the production of medical devices with antimicrobial properties. In this article the influences of the chain length of the hydrophobic block in the amphiphilic polyesters and the process temperature on the particle size distribution (PSD) and the stability of the particles against agglomeration are discussed. According to the results of spectroscopic and viscosimetric investigations the silver precursor is reduced to elemental silver nanoparticles by a single electron transfer process from the poly(ethylene glycol) chain to the silver ion. (paper)

  5. Synthesis of Amphiphilic Block Copolymers for Use in Biomedical Applications

    OpenAIRE

    Carmichael-Baranauskas, Anita Yvonne

    2010-01-01

    The research presented in this thesis focuses on the synthesis of three amphiphilic block copolymer systems containing poly(ethylene oxide) (PEO) blocks. The polymer systems were developed for use in biomedical applications. The first of these is a series of poly(ethylene oxide-b¬-oxazoline) (PEO-b-POX) diblock copolymers for use in the progress towards novel non-viral gene transfer vectors. Poly(ethylene oxide-b¬-2-ethyl-2-oxazoline) (PEO-b-PEOX) and poly(ethylene oxide-b¬-2-methyl-2-o...

  6. Preparation and Characterization of Amphiphilic Triblock Terpolymer-Based Nanofibers as Antifouling Biomaterials

    KAUST Repository

    Cho, Youngjin

    2012-05-14

    Antifouling surfaces are critical for the good performance of functional materials in various applications including water filtration, medical implants, and biosensors. In this study, we synthesized amphiphilic triblock terpolymers (tri-BCPs, coded as KB) and fabricated amphiphilic nanofibers by electrospinning of solutions prepared by mixing the KB with poly(lactic acid) (PLA) polymer. The resulting fibers with amphiphilic polymer groups exhibited superior antifouling performance to the fibers without such groups. The adsorption of bovine serum albumin (BSA) on the amphiphilic fibers was about 10-fold less than that on the control surfaces from PLA and PET fibers. With the increase of the KB content in the amphiphilic fibers, the resistance to adsorption of BSA was increased. BSA was released more easily from the surface of the amphiphilic fibers than from the surface of hydrophobic PLA or PET fibers. We have also investigated the structural conformation of KB in fibers before and after annealing by contact angle measurements, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and coarse-grained molecular dynamics (CGMD) simulation to probe the effect of amphiphilic chain conformation on antifouling. The results reveal that the amphiphilic KB was evenly distributed within as-spun hybrid fibers, while migrated toward the core from the fiber surface during thermal treatment, leading to the reduction in antifouling. This suggests that the antifouling effect of the amphiphilic fibers is greatly influenced by the arrangement of amphiphilic groups in the fibers. © 2012 American Chemical Society.

  7. Poly(dimethylsiloxane)-poly(ethylene oxide)-heparin block copolymers II: Surface characterization and in vitro assessments

    NARCIS (Netherlands)

    Grainger, D.W.; Knutson, K.; Kim, S.W.; Feijen, J.

    1990-01-01

    Amphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), as well as heparin-coated glass beads and tubes were evaluated for the amounts and activities of surface-immobilized heparin. Because the amphiphilic copolymer system is thermodynanmcally predicted to demonstrate l

  8. Synthesis, Characterization, and Aqueous Lubricating Properties of Amphiphilic Graft Copolymers Comprising 2-Methoxyethyl Acrylate

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Røn, Troels; Jankova Atanasova, Katja;

    2014-01-01

    reversible addition–fragmentation chain transfer (RAFT) polymerization, copper-mediated atom transfer radical polymerization (ATRP), and a selective deprotection reaction. Initially, multifunctional ATRP macroinitiators based on PHEMA backbone are prepared by RAFT polymerization. Then ATRP......Amphiphilic anionic and cationic graft copolymers possessing poly(2-hydroxyethyl methacrylate) (PHEMA) backbone and poly(methacrylic acid), poly(2-methoxyethyl acrylate-co-methacrylic acid), and poly(2-methoxyethyl acrylate-co-2-(dimethylamino)ethyl methacrylate) grafts are constructed by merging...

  9. Unimolecular micelles of amphiphilic cyclodextrin-core star-like block copolymers for anticancer drug delivery.

    Science.gov (United States)

    Xu, Zhigang; Liu, Shiying; Liu, Hui; Yang, Cangjie; Kang, Yuejun; Wang, Mingfeng

    2015-11-11

    Well-defined star-like amphiphilic polymers composed of a β-cyclodextrin core, from which 21 hydrophobic poly(lactic acid) arms and hydrophilic poly(ethylene glycol) arms are grafted sequentially, form robust and uniform unimolecular micelles that are biocompatible and efficient in the delivery of anticancer drugs. PMID:26121632

  10. Synthesis of Bioinspired Carbohydrate Amphiphiles that Promote and Inhibit Biofilms.

    Science.gov (United States)

    Dane, Eric L; Ballok, Alicia E; O'Toole, George A; Grinstaff, Mark W

    2014-02-01

    The synthesis and characterization of a new class of bioinspired carbohydrate amphiphiles that modulate Pseudomonas aeruginosa biofilm formation are reported. The carbohydrate head is an enantiopure poly-amido-saccharide (PAS) prepared by a controlled anionic polymerization of β-lactam monomers derived from either glucose or galactose. The supramolecular assemblies formed by PAS amphiphiles are investigated in solution using fluorescence assays and dynamic light scattering. Dried samples are investigated using X-ray, infrared spectroscopy, and transmission electron microscopy. Additionally, the amphiphiles are evaluated for their ability to modulate biofilm formation by the Gram-negative bacterium Pseudomonas aeruginosa. Remarkably, from a library of eight amphiphiles, we identify a structure that promotes biofilm formation and two structures that inhibit biofilm formation. Using biological assays and electron microscopy, we relate the chemical structure of the amphiphiles to the observed activity. Materials that modulate the formation of biofilms by bacteria are important both as research tools for microbiologists to study the process of biofilm formation and for their potential to provide new drug candidates for treating biofilm-associated infections.

  11. Long-Circulating 15 nm Micelles Based on Amphiphilic 3-Helix Peptide-PEG Conjugates

    OpenAIRE

    Dong, He; Dube, Nikhil; Shu, Jessica Y.; Seo, Jai W.; Mahakian, Lisa M; Ferrara, Katherine W.; Xu, Ting

    2012-01-01

    Generating stable, multi-functional organic nanocarriers will have a significant impact on drug formulation. However, it remains a significant challenge to generate organic nanocarriers with a long circulation half-life, effective tumor penetration and efficient clearance of metabolites. We have advanced this goal by designing a new family of amphiphiles based on coiled-coil 3-helix bundle forming peptide-poly(ethylene glycol) conjugates. The amphiphiles self-assemble into monodisperse micell...

  12. SYNTHESIS OF AMPHIPHILIC COMB-SHAPED COPOLYMERS USED FOR SURFACE MODIFICATION OF PVDF MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    徐又一

    2009-01-01

    The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4- hydroxyphenyl) maleimide)(SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate(PEGMA) side groups was achieved by atom transfer radical polymerization(ATRP).The amphiphilic copolymers were characterized by ~1H-NMR, Fourier transform infrared(FTIR) spectroscopy and gel permeation chromatography(GPC).From thermogravimetric analysis (TGA),the decomposition temperature of SHMI-g-PEGMA is low...

  13. New synthetic amphiphilic polymers for steric protection of liposomes in vivo.

    Science.gov (United States)

    Torchilin, V P; Trubetskoy, V S; Whiteman, K R; Caliceti, P; Ferruti, P; Veronese, F M

    1995-09-01

    Carboxy group-terminated synthetic polymers--branched poly(ethylene glycol), poly(acryloylmorpholine), and poly(vinylpyrrolidone)--were made amphiphilic by derivatization with phosphatidyl ethanolamine via the terminal carboxy group and then incorporated into lecithin-cholesterol liposomes prepared by the detergent dialysis method. Following the biodistribution of liposomes in mice, all three polymers were shown to be effective steric protectors for liposomes and were able to sharply increase liposome circulation times in a concentration-dependent manner. The accumulation of liposomes in the liver decreases. The effects observed are similar to those found for liposomes modified with linear poly(ethylene glycol). At low polymer concentration, amphiphilic branched poly(ethylene glycol) seems to be the most effective liposome protector, most probably, because at the same molar content of anchoring groups, each attachment point carries two polymeric chains and doubles the quantity of liposome-grafted polymer comparing to linear poly(ethylene glycol).

  14. Amphiphilic dendronized homopolymers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of second generation of amphiphilic dendronized homopolymers are efficiently synthesized,and their thermoresponsiveness in aqueous solutions and secondary structures in methanol solutions are described.These polymers are constructed in each repeat unit with various generations of hydrophobic 4-aminoproline and hydrophilic oligoethylene glycol (OEG)-based dendrons,and their over-all hydrophilicity is tuned by varying these dendron generations.Polymers with or without the first generation of proline dendron show good water solubility at room temperature,but exhibit typical thermoresponsive behaviors at elevated temperatures as characterized by turbidity measurements using UV-vis spectroscopy,while the polymer with the secondary generation of proline dendron is not soluble in water.All polymers show ordered secondary structures as evidenced by the optical rotation and circular dichroism experiments.Finally,assembly of these amphiphilic homopolymers into porous films via breath figure (BF) technique is described,and polymer structures are found to show significant influence on the morphology of porous film.

  15. Micro- and nanophase separations in hierarchical self-assembly of strongly amphiphilic block copolymer-based ionic supramolecules

    DEFF Research Database (Denmark)

    Ayoubi, Mehran Asad; Zhu, Kaizheng; Nyström, Bo;

    2013-01-01

    block), a class of ionic supramolecules are successfully synthesized whose molecular architecture consists of a poly(styrene) PS block (Linear block) covalently connected to a strongly amphiphilic comb-like block (AmphComb block), i.e. Linear-b-AmphComb. In the melt state, these ionic supramolecules can......By a selective complexation between different alkyltrimethylammonium amphiphiles (C8, C12 and C16) and three different diblock copolymer systems of poly(styrene)-b-poly(methacrylic acid) at various grafting densities X (X = number of alkyl chains per acidic group of the poly(methacrylic acid) PMAA...... supramolecules, based on complexation between a homopolymer of PMAA and the various alkyltrimethylammonium amphiphiles, were prepared, which nanophase separated into S (C8) or C (C12 and C16) domains....

  16. Poly(dimethylsiloxane)-poly(ethyleneoxide)-heparin block copolymers. I. Synthesis and characterization

    NARCIS (Netherlands)

    Grainger, D.W.; Kim, S.W.; Feijen, J.

    1988-01-01

    Amphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), and heparin (PDMS-PEO-Hep) have been prepared via a series of coupling reactions using functionalized prepolymers, diisocyanates, and derivatized heparins. All intermediate steps of the synthesis yield quantifiable

  17. AMPHIPHILIC STAR-BLOCK COPOLYMERS BY IODIDE-MEDIATED RADICAL POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Amphiphilic star-block copolymers composed of polystyrene and poly(acrylic acid) were synthesized by iodidemediated radical polymerization. Firstly, free radical polymerization of styrene was carried out with AIBN as initiator and 1,1,1-trimethyolpropane tri(2-iodoisobutyrate) as chain transfer agent, giving iodine atom ended star-shaped polystyrene with three arm chains, R(polystyrene)3. Secondly, tert-butyl acrylate was polymerization using polystyrene obtained as macro-chain transfer agent, and star-block copolymer, R(polystyrene-b-poly(tert-butyl acrylate))3 with controlled molecular weight was obtained. Finally, amphiphilic star-block copolymer, R(polystyrene-b-poly(acrylic acid))3 was obtained by hydrolysis of R(polystyrene-b-poly(tert-butyl acrylate))3 under acidic condition.

  18. Single-chain crosslinked star polymers via intramolecular crosslinking of self-folding amphiphilic copolymers in water

    OpenAIRE

    Terashima, Takaya; Sugita, Takanori; Sawamoto, Mitsuo

    2015-01-01

    Single-chain crosslinked star polymers with multiple hydrophilic short arms and a hydrophobic core were created as novel microgel star polymers of single polymer chains. The synthetic process involves the intramolecular crosslinking of self-folding amphiphilic random copolymers in water. For this process, amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic olefin pendants were synthesized by ruthenium-catalyzed living radical copolymerization of PEG m...

  19. Structure of adsorption layers of amphiphilic copolymers on inorganic or organic particle surfaces

    OpenAIRE

    Bulychev, Nikolay; Dervaux, Bart; Dimberger, Klaus; Zubov, Vitali; Du Prez, Filip; Eisenbach, Claus D

    2010-01-01

    The structure of adsorption layers of amphiphilic block and block-like copolymers of poly(isobornyl acrylate) and poly(acrylic acid) on the surface of hydrophilic titanium dioxide and hydrophobic copper phthalocyanine (CuPc) pigments in an aqueous studied by the electrokinetic sonic amplitude (ESA) method. The electroacoustic behaviour of the polyelectrolyte block copolymer-coated particles could be described in the context of the polymer gel layer theory. The polymer layer around the particl...

  20. Aggregate of Amphiphilic Block Copolymer as a Pseudo-Stationary Phase in Capillary Electrophoresis

    OpenAIRE

    Nakamura, Tohru; OHKI, Akira; Mishiro, Masaki; Tsuyashima, Osamu; Maeda, Shigeru; ナカムラ, トオル; オオキ, アキラ; ミシロ, マサキ; ツヤシマ, オサム; マエダ, シゲル; 中村, 透; 大木, 章; 艶島, 修; 前田, 滋

    1999-01-01

    The use of an aggregate of amphiphilic block copolymer 1, which consists of poly[(N-acetylimino)ethylene] and poly[(N-pentanoylimino)ethylene], for a pseudo-stationary phase in capillary electrophoresis has been examined. From gel-filtration chromatography, the aggregate from 1 (1-AG) was found to incorporate phenol. When the running solution contains 1-AG and sodium dodecyl sulfate (SDS), the electrophoretic mobility becomes nearly zero. Thus, it is found that when 1-AG and SDS are added to ...

  1. Bilayer Vesicles of Amphiphilic Cyclodextrins: Host Membranes That Recognize Guest Molecules

    NARCIS (Netherlands)

    Falvey, Patrick; Lim, Choon Woo; Darcy, Raphael; Revermann, Tobias; Karst, Uwe; Giesbers, Marcel; Marcelis, Antonius T.M.; Lazar, Adina; Coleman, Anthony W.; Reinhoudt, David N.; Ravoo, Bart Jan

    2005-01-01

    A family of amphiphilic cyclodextrins (6, 7) has been prepared through 6-S-alkylation (alkyl=n-dodecyl and n-hexadecyl) of the primary side and 2-O-PEGylation of the secondary side of a-, B-, and Y-cyclodextrins (PEG=poly(ethylene glycol)). These cyclodextrins form nonionic bilayer vesicles in aqueo

  2. Self-assembly of block copolymer-based ionic supramolecules based upon multi-tail amphiphiles

    DEFF Research Database (Denmark)

    Asad Ayoubi, M.; Almdal, Kristoffer; Zhu, K.;

    2015-01-01

    Utilising simple acid-base titration chemistry, a new family of Linear-b-Amphiphilic Comb (L-b-AC) ionic supramolecules [Soft Matter 2013, 9, 1540-1555] featuring multi-tail side-chains have been synthesized and examined by synchrotron SAXS. To three different parent diblock copolymers of poly(st...

  3. Bilayer vesicles of amphiphilic cyclodextrines: host membranes that recognize guest molecules

    NARCIS (Netherlands)

    Falvey, P.; Lim, C.W.; Darcy, R.; Revermann, T.; Karst, U.; Marcelis, A.T.M.; Coleman, A.W.; Reinhoudt, D.N.; Ravoo, B.J.

    2005-01-01

    A family of amphiphilic cyclodextrins (6, 7) has been prepared through 6-S-alkylation (alkyl=n-dodecyl and n-hexadecyl) of the primary side and 2-O-PEGylation of the secondary side of alpha-, beta-, and gamma-cyclodextrins (PEG=poly(ethylene glycol)). These cyclodextrins form nonionic bilayer vesicl

  4. Amphiphiles for protein solubilization and stabilization

    Science.gov (United States)

    Gellman, Samuel Helmer; Chae, Pil Seok; Laible, Philip D.; Wander, Marc J.

    2012-09-11

    The invention provides amphiphiles for manipulating membrane proteins. The amphiphiles can feature carbohydrate-derived hydrophilic groups and branchpoints in the hydrophilic moiety and/or in a lipophilic moiety. Such amphiphiles are useful as detergents for solubilization and stabilization of membrane proteins, including photosynthetic protein superassemblies obtained from bacterial membranes.

  5. Electrochemical redox responsive polymeric micelles formed from amphiphilic supramolecular brushes.

    Science.gov (United States)

    Feng, Anchao; Yan, Qiang; Zhang, Huijuan; Peng, Liao; Yuan, Jinying

    2014-05-11

    The end-decorated homopolymer poly(ε-caprolactone)-ferrocene threaded onto a β-cyclodextrin-functionalized main-chain polymer can form a class of amphiphilic noncovalent graft copolymers based on the host-guest interactions of the terminal groups on the side chains. These new supramolecular polymer brushes can further self-assemble into micellar aggregates that exhibit reversible assembly and disassembly behavior under an electrochemical redox trigger, which opens up a new route to building dynamic block copolymer topologies. PMID:24681929

  6. High-Capacity Drug Carriers from Common Polymer Amphiphiles.

    Science.gov (United States)

    Zhou, Zhun; Munyaradzi, Oliver; Xia, Xin; Green, Da'Sean; Bong, Dennis

    2016-09-12

    We report herein a dual-purpose role for polyacidic domains in an aqueous-phase polymer amphiphile assembly. In addition to their typical role as ionized water-solubilizing and self-repulsive motifs, we find that polycarboxylic acid domains uniquely enable high levels of hydrophobic drug encapsulation. By attenuated total reflectance infrared spectroscopy, we find significant differences in the carbonyl stretching region of the nanoparticles formed by polyacidic amphiphiles relative to those in soluble, single-domain poly(acrylic acid), suggesting that stabilization may be derived from limited ionization of the carboxylate groups upon assembly. Acidic-hydrophobic diblock polyacrylates were prepared and coassembled with up to 60 wt % camptothecin (CPT) into nanoparticles, the highest loading reported to date. Controlled release of bioactive CPT from polymer nanoparticles is observed, as well as protection from human serum albumin-induced hydrolysis. Surface protection with PEG limits uptake of the CPT-loaded nanoparticles by MCF-7 breast cancer cells, as expected. Acidic-hydrophobic polymer amphiphiles thus have the hallmarks of a useful and general drug delivery platform and are readily accessible from living radical polymerization of cheap, commercially available monomers. We highlight here the potential utility of this common polymer design in high-capacity, controlled-release polymer nanoparticle systems. PMID:27476544

  7. Bulk modification of PDMS microchips by an amphiphilic copolymer.

    Science.gov (United States)

    Xiao, Yan; Yu, Xiao-Dong; Xu, Jing-Juan; Chen, Hong-Yuan

    2007-09-01

    A simple and rapid bulk-modification method based on adding an amphiphilic copolymer during the fabrication process was employed to modify PDMS microchips. Poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) was used as the additive substance. Compared to the native PDMS microchips, both the contact angle and the EOF of the bulk-modified PDMS microchips decreased. The effects of the additive loading and the pH on the EOF were investigated in detail. The bulk-modified PDMS microchips exhibited reproducible and stable EOF behavior. The application of the bulk-modified PDMS microchips was also studied and the results indicated that they could be successfully used to separate amino acids and to suppress protein adsorption.

  8. Synthesis of Dumbbell-shaped Hyperbranched Amphiphilic Block Copolymer by Controlled Atom Transfer Radical Polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Kyoung; An, Sung Guk; Cho, Chang Gi [Center for Advanced Functional Polymers, Department of Fiber and Polymer Science, Hanyang University, Seoul (Korea); Noh, Si Tae [Department of Chemical Engineering, Hanyang University, Ansan (Korea)

    2001-04-01

    Amphiphilic block copolymers containing hydrophilic ethylene glycol core and hyperbranched polystyrene (PS) arm were synthesized by atom transfer radical polymerization using hydrophilic macroinitiator and p-chloromethyl styrene (CMS) as AB type monomer. Hydrophilic poly(ethylene glycol)(PEG) macroinitiators with difuntional groups were synthesized by reacting PEG and 2-bromopropionyl bromide. The chemical structure, molecular weight, and polydispersity index of the amphiphilic block copolymer were characterized by {sup 1}H-NMR spectroscopy and GPC analysis. The molecular weight increased as the reaction time increased. Polydispersity index of the obtained polymer was relatively narrow (below 1.39). To control chain density of the hyperbranched PS, styrene and CMS were copolymerized. It was found that amphiphilic block copolymer molecule underwent conformational change in different solvents based on the result for {sup 1}H-NMR spectroscopic analysis. 29 refs., 8 figs., 2 tabs.

  9. Nanostructured Amphiphilic Star-Hyperbranched Block Copolymers for Drug Delivery.

    Science.gov (United States)

    Seleci, Muharrem; Seleci, Didem Ag; Ciftci, Mustafa; Demirkol, Dilek Odaci; Stahl, Frank; Timur, Suna; Scheper, Thomas; Yagci, Yusuf

    2015-04-21

    A robust drug delivery system based on nanosized amphiphilic star-hyperbranched block copolymer, namely, poly(methyl methacrylate-block-poly(hydroxylethyl methacrylate) (PMMA-b-PHEMA) is described. PMMA-b-PHEMA was prepared by sequential visible light induced self-condensing vinyl polymerization (SCVP) and conventional vinyl polymerization. All of the synthesis and characterization details of the conjugates are reported. To accomplish tumor cell targeting property, initially cell-targeting (arginylglycylaspactic acid; RGD) and penetrating peptides (Cys-TAT) were binding to each other via the well-known EDC/NHS chemistry. Then, the resulting peptide was further incorporated to the surface of the amphiphilic hyperbranched copolymer via a coupling reaction between the thiol (-SH) group of the peptide and the hydroxyl group of copolymer by using N-(p-maleinimidophenyl) isocyanate as a heterolinker. The drug release property and targeting effect of the anticancer drug (doxorobucin; DOX) loaded nanostructures to two different cell lines were evaluated in vitro. U87 and MCF-7 were chosen as integrin αvβ3 receptor positive and negative cells for the comparison of the targeting efficiency, respectively. The data showed that drug-loaded copolymers exhibited enhanced cell inhibition toward U87 cells in compared to MCF-7 cells because targeting increased the cytotoxicity of drug-loaded copolymers against integrin αvβ3 receptor expressing tumor cells. PMID:25816726

  10. Self-assembly behavior of a linear-star supramolecular amphiphile based on host-guest complexation.

    Science.gov (United States)

    Wang, Juan; Wang, Xing; Yang, Fei; Shen, Hong; You, Yezi; Wu, Decheng

    2014-11-01

    A star polymer, β-cyclodextrin-poly(l-lactide) (β-CD-PLLA), and a linear polymer, azobenzene-poly(ethylene glycol) (Azo-PEG), could self-assemble into a supramolecular amphiphilic copolymer (β-CD-PLLA@Azo-PEG) based on the host-guest interaction between β-CD and azobenzene moieties. This linear-star supramolecular amphiphilic copolymer further self-assembled into a variety of morphologies, including sphere-like micelle, carambola-like micelle, naan-like micelle, shuttle-like lamellae, tube-like fiber, and random curled-up lamellae, by tuning the length of hydrophilic or hydrophobic chains. The variation of morphology was closely related to the topological structure and block ratio of the supramolecular amphiphiles. These self-assembly structures could disassemble upon an ultraviolet (UV) light irradiation. PMID:25310380

  11. Amphiphilic γ-PGA nanoparticles administered on rat middle ear mucosa produce adjuvant-like immunostimulation in vivo

    DEFF Research Database (Denmark)

    Nilsson, Johan S; Broos, Sissela; Akagi, Takami;

    2014-01-01

    CONCLUSION: Amphiphilic biodegradable nanoparticles (NPs) composed of poly(γ-glutamic acid) conjugated with L-phenylalanine ethylester (γ-PGA-Phe NPs) applied on the rat middle ear mucosa produce an inflammatory type 1 response. The observation is of relevance for the use of γ-PGA-Phe NPs...

  12. Synthesis of an amphiphilic dendrimer-like block copolymer and its application on drug delivery

    KAUST Repository

    Wang, Shuaipeng

    2014-10-27

    Dendrimer-like amphiphilic copolymer is a kind of three-dimensional spherical structure polymer. An amphiphilic dendrimer-like diblock copolymer, PEEGE-G2-b-PEO(OH)12, constituted of a hydrophobic poly(ethoxyethyl glycidol ether) inner core and a hydrophilic poly(ethylene oxide) outer layer, has been successfully synthesized by the living anionic ring-opening polymerization method. The intermediates and targeted products were characterized with 1H NMR spectroscopy and gel permeation chromatography. The application on drug delivery of dendrimer-like diblock copolymer PEEGE-G2-b-PEO(OH)12 using DOX as a model drug was also studied. The drug loading content and encapsulation efficiency were found at 13.07% and 45.75%, respectively. In vitro release experiment results indicated that the drug-loaded micelles exhibited a sustained release behavior under acidic media.

  13. Synthesis and Characterization of Cross-linked Poly (β-Cyclodextin) Graft Poly(lactic acid) through Direct Polycondensation

    Institute of Scientific and Technical Information of China (English)

    Z.L.Ren; D.D.Lu; Z.Q.Lei

    2007-01-01

    1 Results Polylactide or polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA) have been utilized as bioabsorbable materials in the medical and pharmaceutical fields due to their biodegradable and biocompatible properties[1].However,due to its hydrophobicity and free carboxylic group,PLA or PLGA was not suitable for use to encapsulate the protein.Recently,poly (ε-caprolactone) and poly (D,L-lactide) were respectively grafted onto hydrophilic dextrin and gelatin to obtain the amphiphilic biodeg...

  14. Tandem Facial Amphiphiles for Membrane Protein Stabilization

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Gotfryd, Kamil; Pacyna, Jennifer;

    2010-01-01

    We describe a new type of synthetic amphiphile that is intended to support biochemical characterization of intrinsic membrane proteins. Members of this new family displayed favorable behavior with four of five membrane proteins tested, and these amphiphiles formed relatively small micelles....

  15. Comparison of Facially Amphiphilic versus Segregated Monomers in the Design of Antibacterial Copolymers

    OpenAIRE

    Gabriel, Gregory J.; Maegerlein, Janet A.; Nelson, Christopher F.; Dabkowski, Jeffrey M.; Eren, Tarik; Nüsslein, Klaus; Tew, Gregory N.

    2009-01-01

    A direct comparison of two strategies for designing antimicrobial polymers is presented. Previously, we published several reports on the use of facially amphiphilic (FA) monomers which led to polynorbornenes with excellent antimicrobial activities and selectivities. Our polymers obtained by copolymerization of structurally similar segregated monomers, in which cationic and non-polar moieties reside on separate repeat units, led to polymers with less pronounced activities. A wide range of poly...

  16. Dynamic Ordering Transitions of Liquid Crystals Driven by Interfacial Complexes Formed Between Polyanions and Amphiphilic Polyamines

    OpenAIRE

    Kinsinger, Michael I.; Buck, Maren E.; de Campos, Fernando; Lynn, David M.; Abbott, Nicholas L.

    2008-01-01

    We report the design of an amphiphilic polyamine based on poly(2-alkenyl azlactone) (polymer 1) that strongly couples the formation of polyelectrolyte complexes at aqueous/liquid crystal (LC) interfaces to ordering transitions in the LC. We demonstrate that the addition of a strong anionic polyelectrolyte to aqueous solutions in contact with polymer 1-laden LC interfaces (prepared by Langmuir-Schaefer transfer of monolayers of polymer 1 onto micrometer-thick films of nematic LC) triggers orde...

  17. Novel amphiphilic diblock copolymers by RAFT-polymerization, their self-organization and surfactant properties

    OpenAIRE

    Garnier, Sébastien

    2006-01-01

    The Reversible Addition Fragmentation Chain Transfer (RAFT) process using the new RAFT agent benzyldithiophenyl acetate is shown to be a powerful polymerization tool to synthesize novel well-defined amphiphilic diblock copolymers composed of the constant hydrophobic block poly(butyl acrylate) and of 6 different hydrophilic blocks with various polarities, namely a series of non-ionic, non-ionic comb-like, anionic and cationic hydrophilic blocks. The controlled character of the polymerizations ...

  18. Screening Nylon-3 Polymers, a New Class of Cationic Amphiphiles, for siRNA Delivery

    OpenAIRE

    Nadithe, Venkatareddy; Liu, Runhui; Killinger, Bryan A.; Movassaghian, Sara; Kim, Na Hyung; Moszczynska, Anna B.; Masters, Kristyn S.; Gellman, Samuel H.; Merkel, Olivia M

    2014-01-01

    Amphiphilic nucleic acid carriers have attracted strong interest. Three groups of nylon-3 copolymers (poly-β-peptides) possessing different cationic/hydrophobic content were evaluated as siRNA delivery agents in this study. Their ability to condense siRNA was determined in SYBR Gold assays. Their cytotoxicity was tested by MTT assays, their efficiency of delivering Alexa Fluor-488-labeled siRNA intracellularly in the presence and absence of uptake inhibitors was assessed by flow cytometry, an...

  19. Poly(dimethylsiloxane)-poly(ethyleneoxide)-heparin block copolymers. I. Synthesis and characterization

    OpenAIRE

    D.W. Grainger; S. W. Kim; Feijen, J.

    1988-01-01

    Amphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), and heparin (PDMS-PEO-Hep) have been prepared via a series of coupling reactions using functionalized prepolymers, diisocyanates, and derivatized heparins. All intermediate steps of the synthesis yield quantifiable products with reactive end-groups, while the final products demonstrate bioactive, covalently bound heparin moieties. Due to the solvent systems required, commercial sodium heparin was converted t...

  20. Synthesis and Characterization of Brush Copolymer Poly (propylene oxide)-graft-Poly(N,N-dimethylaminoethyl methacrylate)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wen-qian

    2016-01-01

    In this paper, a amphiphilic brush copolymer poly (propylene oxide)-graft -poly (N,N-dimethylaminoethyl methacrylate) (PPO-g-PDMAEMA) was successfully prepared via the combine of anionic ring opening polymerization and atom transfer radical polymerization(ATRP). The target products were confirmed by GPC and 1H NMR. This well-defined copolymer can supply a promising material as drug and gene carriers and protective materials.

  1. Micellar interactions in water-AOT based droplet microemulsions containing hydrophilic and amphiphilic polymers

    Science.gov (United States)

    Appel, Markus; Spehr, Tinka Luise; Wipf, Robert; Moers, Christian; Frey, Holger; Stühn, Bernd

    2013-11-01

    We investigate the influence of addition of hydrophilic and amphiphilic polymer on percolation behavior and micellar interactions in AOT-based water-in-oil droplet microemulsions. We focus on two series of samples having constant molar water to surfactant ratio W = 20 and constant droplet volume fraction Φ = 30%, respectively. From dielectric spectroscopy experiments, we extract the bending rigidity of the surfactant shell by percolation temperature measurements. Depending on droplet size, we find stabilization and destabilization of the surfactant shell upon addition of hydrophilic poly(ethylene glycol) (PEG) (Mn = 3100 g mol-1) and amphiphilic poly(styrene)-b-poly(ethylene glycol) copolymer with comparable length of the hydrophilic block. Complementary small angle X-ray scattering experiments corroborate the finding of stabilization for smaller droplets and destabilization of larger droplets. Subsequent analysis of dielectric spectra enables us to extract detailed information about micellar interactions and clustering by evaluating the dielectric high frequency shell relaxation. We interpret the observed results as a possible modification of the inter-droplet charge transfer efficiency by addition of PEG polymer, while the amphiphilic polymer shows a comparable, but dampened effect.

  2. Novel thermogelling poly(ε-caprolactone-co-lactide)-poly(ethylene glycol)-poly(ε-caprolactone-co-lactide) aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    Zhi Qiang Jiang; Xian Mo Deng; Jian Yuan Hao

    2007-01-01

    The aqueous solutions of poly(ε-caprolactone-co-lactide)-poly(ethylene glycol)poly(ε-caprolactone-co-lactide) undergoing sol-gel transition as the temperature increases from 20 to 50℃ were successfully prepared.The thermogelling triblock copolymers were synthesized by subtle tuning of the chemical composition and the hydrophilicity/hydrophobicity balance.The sol-gel transition was studied focusing on structure-property relationship.The amphiphilic copolymer formed micelles in aqueous solutions.It is believed to have potential applications in drug delivery and tissue engineering.

  3. Self-assembling Behavior of Amphiphilic Copolymer Containing Cross-linked Hydrophilic Block in Ethanol

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The self-assembly behavior of the amphiphilic block copolymer poly( methyl methacrylate)-block-poly( lead dimethacrylate) (PMMA-b-PLDMA) with cross-linked hydrophilic block (PLDMA) in ethanol was investigated. The results show that the size and morphology of the resulting micelle or micellar aggregates are ascribed to the content of ethanol and the nature of the solvent mixture. PbS nanoparticles were formed in the micelle by in situ reaction with H2S gas. The morphology and size of the self-assembly objects were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  4. Periodically Grafted Amphiphilic Copolymers: Effects of Steric Crowding and Reversal of Amphiphilicity.

    Science.gov (United States)

    Mandal, Joydeb; Ramakrishnan, S

    2015-06-01

    Two series of periodically clickable polyesters were prepared; one of them carries alkylene segments along its backbone, whereas the other carries poly(ethylene glycol) (PEG) segments. These polyesters were clicked with either MPEG-350 azide or docosyl (C22) azide to yield periodically grafted amphiphilic copolymers (PGACs) carrying either flexible hydrophilic or crystallizable hydrophobic backbone segments. The immiscibility between hydrocarbon and PEG segments causes both of these systems to fold in either a zigzag or hairpin-like conformation; the hairpin-like conformation appears to be preferred when flexible PEG segments are present in the backbone. The folded chains further reorganize in the solid state to develop a lamellar morphology that permits the collocation of the PEG and hydrocarbon (HC) segments within alternate domains; evidence for the self-segregation was gained from DSC, SAXS, and AFM studies. SAXS studies revealed the formation of an extended lamellar structure, whereas AFM images showed uniform layered morphology with layer heights that matched reasonably well with the interlamellar spacing obtained from the SAXS study. Labeling one representative PGAC, carrying crystallizable long alkylene segments in the backbone and pendant PEG-350 side chains, with a small mole fraction of pyrene fluorophore permitted the examination of the conformational transition that occurs upon going from a good to a poor solvent; this single-chain folded conformation, we postulate, is the intermediate that organizes into the lamellar morphology.

  5. Amphiphilic Soft Janus Particles as Interfacial Stabilizers

    Science.gov (United States)

    Wang, Wenda; Niu, Sunny; Sosa, Chris; Prud'Homme, Robert; Priestley, Rodney; Priestley Polymer group Team; Prud'homme Research Group Team

    Janus particles, which incorporate two or more ``faces'' with different chemical functionality, have attracted great attention in scientific research. Amphiphilic Janus particles have two faces with distinctly different hydrophobicity. This can be thought of as colloidal surfactants. Theoretical studies on the stabilization of emulsions using Janus particles have confirmed higher efficiency. Herein we synthesize the narrow distributed amphiphilic polymeric Janus particles via Precipitation-Induced Self-Assembly (PISA). The efficiency of the amphiphilic Janus particles are tested on different oil/water systems. Biocompatible polymers can also be used on this strategy and may potentially have wide application for food emulsion, cosmetics and personal products.

  6. Nanocapsules templated on liquid cores stabilized by graft amphiphilic polyelectrolytes

    Science.gov (United States)

    Szafraniec, Joanna; Janik, Małgorzata; Odrobińska, Joanna; Zapotoczny, Szczepan

    2015-03-01

    A surfactant-free method of preparation of nanocapsules templated on liquid cores using amphiphilic graft polyelectrolytes was developed. A model photoactive copolymer, poly(sodium 2-acrylamido-2-methyl-1-propanesulfonate) with grafted poly(vinylnaphthalene) chains (PAMPS-graft-PVN) was used to stabilize toluene droplets in an aqueous emulsion. The macromolecules, due to their amphiphilic character and the presence of strong ionic groups, tend to undergo intramolecular aggregation in water but at the water-oil interface less compact conformation is preferred with PVN grafts anchoring in the oil phase and the charged PAMPS main chains residing in the aqueous phase, thus stabilizing the nanoemulsion droplets. Formation of such nanocapsules was confirmed by dynamic light scattering measurements as well as SEM and cryo-TEM imaging. Grafting density and content of the chromophores in the graft copolymers were varied in order to achieve high stability of the coated nanodroplets. It was shown that the capsules are better stabilized by the copolymers with many short hydrophobic grafts than with fewer but longer ones. Use of photoactive polyelectrolytes enabled spectroscopic investigation of the relationship between conformation of the macromolecules and stabilization of the oil-core nanocapsules. Long-term stability of the nanocapsules was achieved and further increased by multilayer shell formation using polyelectrolytes deposited via the layer-by-layer approach. The obtained capsules served as efficient nanocontainers for a hydrophobic fluorescent probe. The proposed strategy of nanocapsule preparation may be easily extended to biologically relevant polymers and applied to fabricate liquid core nanodelivery systems without the need of using low molecular weight additives which may have adverse effects in numerous biomedical applications.A surfactant-free method of preparation of nanocapsules templated on liquid cores using amphiphilic graft polyelectrolytes was developed

  7. Aminoglycoside-derived amphiphilic nanoparticles for molecular delivery.

    Science.gov (United States)

    Miryala, Bhavani; Godeshala, Sudhakar; Grandhi, Taraka Sai Pavan; Christensen, Matthew D; Tian, Yanqing; Rege, Kaushal

    2016-10-01

    The development of effective drug carriers can lead to improved outcomes in a variety of disease conditions. Aminoglycosides have been used as antibacterial therapeutics, and are attractive as monomers for the development of polymeric materials in various applications. Here, we describe the development of novel aminoglycoside-derived amphiphilic nanoparticles for drug delivery, with an eye towards ablation of cancer cells. The aminoglycoside paromomycin was first cross-linked with resorcinol diglycidyl ether leading to the formation of a poly (amino ether), PAE. PAE molecules were further derivatized with methoxy-terminated poly(ethylene glycol) or mPEG resulting in the formation of mPEG-PAE polymer, which self-assembled to form nanoparticles. Formation of the mPEG-PAE amphiphile was characterized using (1)H NMR, (13)C NMR, gel permeation chromatography (GPC) and FTIR spectroscopy. Self-assembly of the polymer into nanoparticles was characterized using dynamic light scattering, zeta potential analyses, atomic force microscopy (AFM) and the pyrene fluorescence assay. mPEG-PAE nanoparticles were able to carry significant amounts of doxorubicin (DOX), presumably by means of hydrophobic interactions between the drug and the core. Cell-based studies indicated that mPEG-PAE nanoparticles, loaded with doxorubicin, were able to induce significant loss in viabilities of PC3 human prostate cancer, MDA-MB-231 human breast cancer, and MB49 murine bladder cancer cells; empty nanoparticles resulted in negligible losses of cell viability under the conditions investigated. Taken together, our results indicate that the mPEG-PAE nanoparticle platform is attractive for drug delivery in different applications, including cancer. PMID:27472455

  8. SYNTHESIS OF AMPHIPHILIC COMB-SHAPED COPOLYMERS USED FOR SURFACE MODIFICATION OF PVDF MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    Jian-hua Li; You-yi Xu; Jian-hua Wang; Chun-hui Du

    2009-01-01

    The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4-hydroxyphenyl) maleimide) (SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate (PEGMA) side groups was achieved by atom transfer radical polymerization (ATRP). The amphiphilic copolymers were characterized by ~1H-NMR, Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). From thermogravimetric analysis (TGA), the decomposition temperature of SHMI-g-PEGMA is lower than that of SHMI, and the graft ratio of PEGMA in the SHMI is 18.6%. The experimental results of solubilities showed that SHMI, SHMI-Br and SHMI-g-PEGMA had excellent solubility in polar solvents, such as DMF, DMSO and NMP. SHMI-g-PEGMA had higher solubilities in H_2O and methanol, while lower solubility in CHCl_3 than SHMI and SHMI-Br. PVDF blend membranes were prepared via the standard immersion precipitation phase inversion process, using amphiphilic SHMI-g-PEGMA copolymer as additives. The morphology and hydrophilicity of the blend membrane surfaces were characterized by SEM and water contact angle. It is demonstrated that the blend membranes display enhanced hydrophilicity compared to unmodified PVDF membranes. Finally, the permeation and anti-fouling properties were investigated. The result shows that amphiphilic SHMI-g-PEGMA copolymer increases the permeatability and anti-fouling property of PVDF membranes greatly.

  9. Characterization of Fe3O4/P(St-MPEO) Amphiphilic Magnetic Polymer Microspheres

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Amphiphilic magnetic microspheres consisting of styrene and poly(ethylene oxide) macromonomer(MPEO) were prepared by dispersion copolymerization in the presence of Fe3O4 magnetic fluid in an ethanol/water medium. The sizes of the magnetic microspheres and their distribution were characterized by means of scanning electron microscopy(SEM). The surface morphology and the average surface roughness of the microspheres were investigated by virtue of atomic force microscopy(AFM). It was found that the microspheres exhibit microscopic phase-separate and the mean square surface roughness of the microspheres increases with increasing MPEO used in the copolymerization. The amphiphilic magnetic microspheres containing 0.4-3.5 mg/g hydroxyl groups could be prepared from MPEO with different concentrations and styrene.

  10. Novel fluorescent amphiphilic block copolymers: photophysics behavior and interactions with DNA

    Directory of Open Access Journals (Sweden)

    2007-06-01

    Full Text Available In this study, novel amphiphilic fluorescent copolymers poly(N-vinylpyrrolidone-b-poly(N-methacryloyl-N'-(α-naphthylthiourea (PVP-b-PNT were synthesized via ATRP with poly(N-vinylpyrrolidone-Cl as macroinitiator and N-methacryloyl-N'-α-naphthylthiourea (NT as hydrophobic segment. PVP-b-PNT copolymers were characterized by 1H NMR, GPC-MALLS and fluorescence measurements. The aggregation behavior of PVP-b-PNT in water was investigated by transmission electron microscope (TEM and dynamic light scattering (DLS measurement. The photophysics behavior of PVP-b-PNT showed that block copolymer formed strong excimer. The interaction of DNA with the block copolymer made the excimer of block copolymer quench. The cytotoxicity result of PVP-b-PNT in cell culture in vitro indicated that this copolymer PVP-b-PNT had good biocompatibility.

  11. High-performance Polymer Membranes with Multi-functional Amphiphilic Micelles for CO2 Capture.

    Science.gov (United States)

    Kim, Sang Jin; Jeon, Harim; Kim, Dong Jun; Kim, Jong Hak

    2015-11-01

    Herein, we report a high performance polymer membrane with simultaneously large improvements in the CO2 permeability and CO2/N2 selectivity. These improvements are obtained by incorporation of a multi-functional amphiphilic comb copolymer micelle, that is, poly(dimethylsiloxane)-g-poly(oxyethylene methacrylate) (PDMS-g-POEM), into a poly(amide-b-ethylene oxide) (Pebax) matrix. Both CO2 and N2 permeabilities continuously increased with PDMS-g-POEM content, whereas the CO2/N2 selectivity increased up to 40 wt % of PDMS-g-POEM, which enabled the maximum performance to approach the upper bound limit (2008). The membranes with PDMS-g-POEM exhibited greater CO2 permeability and CO2/N2 selectivity than those with a zeolitic imidazolate framework (ZIF-8), a well-known expensive inorganic filler, indicating the effectiveness of PDMS-g-POEM micelles for CO2 capture.

  12. Computational Amphiphilic Materials for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Naresh eThota

    2015-10-01

    Full Text Available Amphiphilic materials can assemble into a wide variety of morphologies and have emerged as a novel class of candidates for drug delivery. Along with a large number of experiments reported, computational studies have been also conducted in this field. At an atomistic/molecular level, computations can facilitate quantitative understanding of experimental observations and secure fundamental interpretation of underlying phenomena. This review summarizes the recent computational efforts on amphiphilic copolymers and peptides for drug delivery. Atom-resolution and time-resolved insights are provided from bottom-up to microscopically elucidate the mechanisms of drug loading/release, which are indispensable in the rational screening and design of new amphiphiles for high-efficacy drug delivery.

  13. Nanostructured assemblies from amphiphilic ABC multiblock polymers

    Science.gov (United States)

    Hillmyer, Marc A.

    2012-02-01

    Amphiphilic AB diblock copolymers containing a water compatible segment can self-assemble in aqueous media to give supramolecular structures that include simple spherical micelles and macromolecular vesicles termed polymersomes. Amphiphilic ABA triblocks with hydrophobic end blocks can adopt analogous structures but can also form gels at high polymer concentrations. The structural and chemical diversity demonstrated in block copolymer micelles and gels makes them attractive for applications ranging from drug delivery to personal care products to nanoreactors. The inclusion of a third block in amphiphilic ABC triblock systems can lead to a much wider array of self-assembled structures that depend not only on composition but also on block sequence, architecture and incompatibility considerations. I will present our recent efforts on tuning micelle and gel structure and behavior using controlled architecture ABC triblocks. The combination of diverse polymer segments into a single macromolecule is a powerful method for development of self-assembled structures with both new form and new function.

  14. Prediction on amphiphilicity of hypocrellin derivatives

    Institute of Scientific and Technical Information of China (English)

    谢杰; 马江华; 赵井泉

    2002-01-01

    Hypocrellins are most suitable for photodynamic therapy (PDT) of the diseases occurring in the superficial layer, such as microvascular diseases, because of their special absorption spectral properties. However, hypocrellins and most of their derivatives are basically lipophilic, while the hydrophilic derivatives lose the PDT activity in vivo. Therefore, the key problem for practical application of PDT of microvascular diseases focuses on finding the derivatives which possess optimized amphiphilicity. Herein, we developed a theoretical method to estimate the amphi-philicity of a molecule by the calculated average polarity. Compared with the experimentally measured results, the method is proved to be applicable. Based on the computation and available experimental results, it can be concluded that the derivative must have the polarities around C.22 for optimized amphiphilicity.

  15. Prediction on amphiphilicity of hypocrellin derivatives

    Institute of Scientific and Technical Information of China (English)

    谢杰; 马江华; 赵井泉

    2002-01-01

    Hypocrellins are most suitable for photodynamic therapy (PDT) of the diseases occurring in the superficial layer, such as microvascular diseases, because of their special absorption spectral properties. However, hypocrellins and most of their derivatives are basically lipophilic, while the hydrophilic derivatives lose the PDT activity in vivo. Therefore, the key problem for practical application of PDT of microvascular diseases focuses on finding the derivatives which possess optimized amphiphilicity. Herein, we developed a theoretical method to estimate the amphiphilicity of a molecule by the calculated average polarity. Compared with the experimentally measured results, the method is proved to be applicable. Based on the computation and available experimental results, it can be concluded that the derivative must have the polarities around 0.22 for optimized amphiphilicity.

  16. Non-Surface Activity of Cationic Amphiphilic Diblock Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, Rati Ranjan; Yamada, Tasuku; Matsuoka, Hideki, E-mail: ratiranjan@immt.res.in, E-mail: matsuoka@star.polym.kyoto-u.ac.jp [Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2011-09-19

    Cationic amphiphilic diblock copolymers containing quaternized poly (2-vinylpyridine) chain as a hydrophilic segment (PIp-b-PNMe2VP) were synthesized by living anionic polymerization. By IR measurement, we confirmed the quaternization of the polymer (PIp-b-PNMe2VP), and determined the degree of quaternization by conductometric titration. The surface tension experiment showed that the polymers are non-surface active in nature. The foam formation of the polymer solutions was also investigated with or without added salt. Almost no foam formation behavior was observed without added salt, while a little foam was observed in the presence of 1M NaCl. The critical micelle concentration (cmc) of the diblock copolymers with 3 different chain lengths was measured by the static light scattering method. The cmc values obtained in this study were much lower than the values obtained for anionic non-surface active diblock polymers studied previously. The hydrodynamic radii of the polymer micelle increased slightly in the presence of 1 M NaCl. The transmission electron microscopic images revealed spherical micelles in pure water. In the presence of salt, the cmc values increased as was the case for anionic polymers, which is unlike conventional surfactant systems but consistent with non-surface active anionic block copolymers. The microviscosity of the micelle core was evaluated using Coumarin-153 as a fluorescent anisotropy probe using steady-sate fluorescence depolarization. Non-surface activity has been proved to be universal for ionic amphiphilic block copolymers both for anionic and cationic. Hence, the origin of non-surface activity is not the charged state of water surface itself, but should be an image charge repulsion at the air/water interface.

  17. Synthesis of Thermoresponsive Amphiphilic Polyurethane Gel as a New Cell Printing Material near Body Temperature.

    Science.gov (United States)

    Tsai, Yi-Chun; Li, Suming; Hu, Shiaw-Guang; Chang, Wen-Chi; Jeng, U-Ser; Hsu, Shan-hui

    2015-12-23

    Waterborne polyurethane (PU) based on poly(ε-caprolactone) (PCL) diol and a second oligodiol containing amphiphilic blocks was synthesized in this study. The microstructure was characterized by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and rheological measurement of the PU dispersion. The surface hydrophilicity measurement, infrared spectroscopy, wide-angle X-ray diffraction, mechanical and thermal analyses were conducted in solid state. It was observed that the presence of a small amount of amphiphilic blocks in the soft segment resulted in significant changes in microstructure. When 90 mol % PCL diol and 10 mol % amphiphilic blocks of poly(l-lactide)-poly(ethylene oxide) (PLLA-PEO) diol were used as the soft segment, the synthesized PU had a water contact angle of ∼24° and degree of crystallinity of ∼14%. The dispersion had a low viscosity below room temperature. As the temperature was raised to body temperature (37 °C), the dispersion rapidly (∼170 s) underwent sol-gel transition with excellent gel modulus (G' ≈ 6.5 kPa) in 20 min. PU dispersions with a solid content of 25-30% could be easily mixed with cells in sol state, extruded by a 3D printer, and deposited layer by layer as a gel. Cells remained alive and proliferating in the printed hydrogel scaffold. We expect that the development of novel thermoresponsive PU system can be used as smart injectable hydrogel and applied as a new type of bio-3D printing ink.

  18. Self-Assembly and Hydrogelation of Peptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Wahyudi Priyono Suwarso

    2012-04-01

    Full Text Available Seven peptide amphiphiles were successfully synthesized using solid phase peptide synthesis method. Peptide amphiphiles were characterized using matrix assisted laser desorption/ionization (MALDI. Atomic force microscopy (AFM study showed that peptide amphiphiles having glycine, valine, or proline as linker, self-assembled into 100-200 nm nanofibers structure. According to our research, both peptide amphiphile with positive and negative charges bear similar self-assembly properties. Peptide amphiphile also showed its capability as low molecular weight gelator (LMWG. Peptide amphiphiles bearing C-16 and C-12 as alkyl showed better hydrogelation properties than C-8 alkyl. Five out of seven peptide amphiphiles have minimum gelation concentration (MGC lower than 1% (w/v.

  19. Investigation on the ion pair amphiphiles and their in vitro release of amantadine drug based on PLGA–PEG–PLGA gel

    International Nuclear Information System (INIS)

    The amantadine drug and oleic acid surfactant are used to form amantadine-based ion pair amphiphiles based on proton transfer reaction between the drug and the surfactant molecules. The ion pair amphiphiles are characterized by 1H-nuclear magnetic resonance, Fourier transform infrared spectroscopy, and X-ray diffraction. Self-assembly properties of amantadine-based ion pair amphiphiles are studied by surface tension determination, transmission electron microscopy, zeta potential, and dynamic light scattering. The aggregation behavior studies indicate that the as-prepared ion pair amphiphiles can self-assemble into vesicles with the size of 200–300 nm in aqueous solution. The drug release results show that the amantadine release rate could be well controlled by incorporating the amantadine-based ion pair vesicles in poly (lactic-co-glycolic acid)-poly (ethylene glycol)-poly (lactic-co-glycolic acid) (PLGA–PEG–PLGA) copolymer hydrogel. The drug release from the AT–OA vesicle-loaded PLGA–PEG–PLGA hydrogel is significantly inhibited in comparison with the AT-loaded PLGA–PEG–PLGA hydrogel. The present work thus demonstrates that the vesicle-loaded hydrogel is a good candidate for the drug delivery system with long-term controlled drug release behavior

  20. Investigation on the ion pair amphiphiles and their in vitro release of amantadine drug based on PLGA–PEG–PLGA gel

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaoxia, E-mail: yxx-678@163.com; Ji, Xiaoqing; Shi, Chunhuan; Liu, Jing [Shandong University, School of Pharmaceutical Science and Center for Pharmaceutical Research & Drug Delivery Systems (China); Wang, Haiyang [Institute of Materia Medica Shandong Academy of Medical Sciences, Shandong Taitian Newdrug Discovery Co.Ltd (China); Luan, Yuxia, E-mail: yuxialuan@sdu.edu.cn [Shandong University, School of Pharmaceutical Science and Center for Pharmaceutical Research & Drug Delivery Systems (China)

    2014-12-15

    The amantadine drug and oleic acid surfactant are used to form amantadine-based ion pair amphiphiles based on proton transfer reaction between the drug and the surfactant molecules. The ion pair amphiphiles are characterized by {sup 1}H-nuclear magnetic resonance, Fourier transform infrared spectroscopy, and X-ray diffraction. Self-assembly properties of amantadine-based ion pair amphiphiles are studied by surface tension determination, transmission electron microscopy, zeta potential, and dynamic light scattering. The aggregation behavior studies indicate that the as-prepared ion pair amphiphiles can self-assemble into vesicles with the size of 200–300 nm in aqueous solution. The drug release results show that the amantadine release rate could be well controlled by incorporating the amantadine-based ion pair vesicles in poly (lactic-co-glycolic acid)-poly (ethylene glycol)-poly (lactic-co-glycolic acid) (PLGA–PEG–PLGA) copolymer hydrogel. The drug release from the AT–OA vesicle-loaded PLGA–PEG–PLGA hydrogel is significantly inhibited in comparison with the AT-loaded PLGA–PEG–PLGA hydrogel. The present work thus demonstrates that the vesicle-loaded hydrogel is a good candidate for the drug delivery system with long-term controlled drug release behavior.

  1. Designing new symmetrical facial oligothiophene amphiphiles

    NARCIS (Netherlands)

    Janeliunas, Dainius; Eelkema, Rienk; Nieto-Ortega, Belén; Ramírez Aguilar, Francisco J; López Navarrete, Juan T; van der Mee, Lars; Stuart, Marc C A; Casado, Juan; van Esch, Jan H

    2013-01-01

    In this study we designed a new class of symmetrical facial oligothiophene amphiphiles, which could be obtained in fewer steps than for previously reported analogues, but still possess the specific substituent sequence to control their backbone curvature. This novel design allows the late-stage intr

  2. Bola-amphiphile self-assembly

    DEFF Research Database (Denmark)

    Svaneborg, Carsten

    2012-01-01

    Bola-amphiphiles are rod-like molecules where both ends of the molecule likes contact with water, while the central part of the molecule dislikes contact with water. What do such molecules do when they are dissolved in water? They self-assemble into micelles. This is a Dissipartive particle dynam...

  3. Peptide Amphiphiles in Corneal Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Martina Miotto

    2015-08-01

    Full Text Available The increasing interest in effort towards creating alternative therapies have led to exciting breakthroughs in the attempt to bio-fabricate and engineer live tissues. This has been particularly evident in the development of new approaches applied to reconstruct corneal tissue. The need for tissue-engineered corneas is largely a response to the shortage of donor tissue and the lack of suitable alternative biological scaffolds preventing the treatment of millions of blind people worldwide. This review is focused on recent developments in corneal tissue engineering, specifically on the use of self-assembling peptide amphiphiles for this purpose. Recently, peptide amphiphiles have generated great interest as therapeutic molecules, both in vitro and in vivo. Here we introduce this rapidly developing field, and examine innovative applications of peptide amphiphiles to create natural bio-prosthetic corneal tissue in vitro. The advantages of peptide amphiphiles over other biomaterials, namely their wide range of functions and applications, versatility, and transferability are also discussed to better understand how these fascinating molecules can help solve current challenges in corneal regeneration.

  4. Synthesis and characterization of PEG-coated poly(ethyl cyanoacrylate) nanoparticles

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jin-hua; SUN Duo-xian

    2001-01-01

    Injectable nanoparticle carrier, poly (ethylene glycol)-coated poly (ethyl cyanoacrylate) has been prepared by a simple method. At First, synthesizing PEG macromonomer of poly(ethylene glycol) monomethyl ether with acryloyl chlo ride, then graft copolymer of poly(ethyl cyanoacrylate) and poly(ethylene glycol)was yield by free radical polymerization of ethyl cyanoacrylate with PEG macromonomer in toluene solvent. Characterization of the copolymer has been per formed by FTIR, 1H-NMR and GPC analysis. Nanoparticles were easily prepared from the obtained amphiphilic copolymer.

  5. Poly(glycerol adipate)-fatty acid esters as versatile nanocarriers

    DEFF Research Database (Denmark)

    Weiss, Verena M; Naolou, Toufik; Hause, Gerd;

    2012-01-01

    Poly(glycerol adipate) (PGA) is a biodegradable polymer with promising features for nanoparticulate drug carrier systems. By acylation of PGA with fatty acids, composite systems with amphiphilic properties can be obtained. Variation of the fatty acid (laurate, stearate and behenate) and their sub......Poly(glycerol adipate) (PGA) is a biodegradable polymer with promising features for nanoparticulate drug carrier systems. By acylation of PGA with fatty acids, composite systems with amphiphilic properties can be obtained. Variation of the fatty acid (laurate, stearate and behenate...

  6. ANIONIC SYNTHESIS OF A "CLICKABLE" MIDDLE-CHAIN AZIDEFUNCTIONALIZED POLYSTYRENE AND ITS APPLICATION IN SHAPE AMPHIPHILES

    Institute of Scientific and Technical Information of China (English)

    Kan Yue; Jinlin He; Chang Liu; Mingjun Huang; Xue-Hui Dong; Kai Guo; Peihong Ni

    2013-01-01

    "Click chemistry" is,by definition,a general functionalization methodology (GFM) and its marriage with living anionic polymerization is particularly powerful in precise macromolecular synthesis.This paper reports the synthesis of a "clickable" middle-chain azide-functionalized polystyrene (mPS-N3) by anionic polymerization and its application in the preparation of novel shape amphiphiles based on polyhedral oligomeric silsesquioxane (POSS).The mPS-N3 was synthesized by coupling living poly(styryl)lithium chains (PSLi) with 3-chloropropylmethyldichlorosilane and subsequent nucleophilic substitution of the chloro group in the presence of sodium azide.Excess PSLi was end-capped with ethylene oxide to facilitate its removal by flash chromatography.The mPS-N3 was then derived into a giant lipid-like shape amphiphile in two steps following a sequential "click" strategy.The copper(I)-catalyzed azide-alkyne cycloaddition between mPS-N3 and alkyne-functionalized vinyl-substituted POSS derivative (VPOSS-alkyne) ensured quantitative ligation to give polystyrene with VPOSS tethered at the middle of the chain (mPS-VPOSS).The thiol-ene reaction with 1-thioglycerol transforms the vinyl groups on the POSS periphery to hydroxyls,resulting in an amphiphilic shape amphiphile,mPS-DPOSS.This synthetic approach is highly efficient and modular.It demonstrates the "click" philosophy of facile complex molecule construction from a library of simple building blocks and also suggests that mPS-N3 can be used as a versatile "clickable" motif in polymer science for the precise synthesis of complex macromolecules.

  7. Perfluorocyclobutyl-containing Amphiphilic Block Copolymers Synthesized by RAFT Polymerization

    Institute of Scientific and Technical Information of China (English)

    LI, Yongjun; ZHANG, Sen; FENG, Chun; ZHANG, Yaqin; LI, Qingnuan; LI, Wenxin; HUANG, Xiaoyu

    2009-01-01

    Amphiphilic block copolymers containing hydrophobic perfluorocyclobutyl-based (PFCB) polyacrylate and hydrophilic poly(ethylene glycol) (PEG) segments were prepared via reversible addition-fragmentation chain transfer (RAP-T) polymerization. The PFCB-containing acrylate monomer, p-(2-(p-tolyloxy)perfluorocyclobutoxy)phenyl acrylate, was first synthesized from commercially available compounds in good yields, and this kind of acrylate monomer can be homopolymerized by free radical polymerization or RAFT polymerization. Kinetic study showed the 2,2'-azobis(isobutyronitrile) (AIBN) initiated and cumyl dithiobenzoate (CDB) mediated RAFT polymerization was in a living fashion, as suggested by the fact that the number-average molecular weights (M_n) increased linearly with the conversions of the monomer, while the polydispersity indices kept less than 1.10. The block polymers with narrow molecular weight distributions (M_w/M_n≤1.21) were prepared through RAFT polymerization using PEG monomethyl ether capped with 4-cyanopentanoic acid dithiobenzoate end group as the macro chain transfer agent (mPEG-CTA). The length of the hydrophobic segment can be tuned by the feed ratio of the PFCB-based acrylate monomer and the extending of the polymerization time. The micellization behavior of the block copolymers in aqueous media was investigated by the fluorescence probe technique.

  8. Biodegradable amphiphilic block copolymers containing functionalized PEO blocks:Controlled synthesis and biomedical potentials

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of controllable amphiphilic block copolymers composed of poly(ethylene oxide)(PEO) as the hydrophilic block and poly(ε-caprolactone)(PCL) as the hydrophobic block with the amino terminal group at the end of the PEO chain(PCL-b-PEO-NH2) were synthesized.Based on the further reaction of reactive amino groups,diblock copolymers with functional carboxyl groups(PCL-b-PEO-COOH) and functional compounds RGD(PCL-b-PEO-RGD) as well as the triblock copolymers with thermosensitive PNIPAAm blocks(PCL-b-PEO-b-PNIPAAM) were synthesized.The well-controlled structures of these copolymers with functional groups and blocks were characterized by gel permeation chromatography(GPC) and 1H NMR spectroscopy.These copolymers with functionalized hydrophilic blocks were fabricated into microspheres for the examination of biofunctions via cell culture experiments and in vitro drug release.The results indicated the significance of introducing functional groups(e.g.,NH2,COOH and RGD) into the end of the hydrophilic block of amphiphilic block copolymers for biomedical potentials in tissue engineering and controlled drug release.

  9. Amphiphilic Beads as Depots for Sustained Drug Release Integrated into Fibrillar Scaffolds

    Science.gov (United States)

    Gaharwar, Akhilesh K.; Mihaila, Silvia M.; Kulkarni, Ashish A.; Patel, Alpesh; Di Luca, Andrea; Reis, Rui L.; Gomes, Manuela E.; van Blitterswijk, Clemens; Moroni, Lorenzo; Khademhosseini, Ali

    2014-01-01

    Native extracellular matrix (ECM) is a complex fibrous structure loaded with bioactive cues that affects the surrounding cells. A promising strategy to mimicking native tissue architecture for tissue engineering applications is to engineer fibrous scaffolds using electrospinning. By loading appropriate bioactive cues within these fibrous scaffolds, various cellular functions such as cell adhesion, proliferation and differentiation can be regulated. Here, we report on the encapsulation and sustained release of model hydrophobic drug (dexamethasone (Dex)) within beaded fibrillar scaffold of poly(ethylene oxide terephthalate)-poly(butylene terephthalate) (PEOT/PBT), a polyether-ester multiblock copolymer to direct differentiation of human mesenchymal stem cells (hMSCs). The amphiphilic beads act as depots for sustained drug release that is integrated into the fibrillar scaffolds. The entrapment of Dex within the beaded structure results in sustained release of drug over the period of 28 days. This is mainly attributed to the diffusion driven release of Dex from the amphiphilic electrospun scaffolds. In vitro results indicate that hMSCs cultured on Dex containing beaded fibrillar scaffolds exhibit an increase in osteogenic differentiation potential, as evidenced by increased alkaline phosphatase (ALP) activity, compared to the direct infusion of Dex in culture medium. The formation of mineralized matrix is also significantly enhanced due to the controlled Dex release from the fibrous scaffolds. This approach can be used to engineer scaffolds with appropriate chemical cues to direct tissue regeneration. PMID:24794894

  10. Hydration-Induced Phase Separation in Amphiphilic Polymer Matrices and its Influence on Voclosporin Release

    Energy Technology Data Exchange (ETDEWEB)

    Khan, I. John [The State Univ. of New Jersey, Piscataway, NJ (United States); Murthy, N. Sanjeeva [The State Univ. of New Jersey, Piscataway, NJ (United States); Kohn, Joachim [The State Univ. of New Jersey, Piscataway, NJ (United States)

    2015-10-30

    Voclosporin is a highly potent, new cyclosporine -- a derivative that is currently in Phase 3 clinical trials in the USA as a potential treatment for inflammatory diseases of the eye. Voclosporin represents a number of very sparingly soluble drugs that are difficult to administer. It was selected as a model drug that is dispersed within amphiphilic polymer matrices, and investigated the changing morphology of the matrices using neutron and x-ray scattering during voclosporin release and polymer resorption. The hydrophobic segments of the amphiphilic polymer chain are comprised of desaminotyrosyl-tyrosine ethyl ester (DTE) and desaminotyrosyl-tyrosine (DT), and the hydrophilic component is poly(ethylene glycol) (PEG). Water uptake in these matrices resulted in the phase separation of hydrophobic and hydrophilic domains that are a few hundred Angstroms apart. These water-driven morphological changes influenced the release profile of voclosporin and facilitated a burst-free release from the polymer. No such morphological reorganization was observed in poly(lactide-co-glycolide) (PLGA), which exhibits an extended lag period, followed by a burst-like release of voclosporin when the polymer was degraded. An understanding of the effect of polymer composition on the hydration behavior is central to understanding and controlling the phase behavior and resorption characteristics of the matrix for achieving long-term controlled release of hydrophobic drugs such as voclosporin.

  11. Gold Nanoparticles Protected with Thiol-Derivatized Amphiphilic Poly( -caprolactone)-b-poly(acrylic acid)

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Hvilsted, Søren

    2008-01-01

    )2 catalysed ATRP of tBA. ATRP of tBA provided diblock copolymers with low polydispersity index (1.17-1.39) while preserving the protected thiol function. Sequential or simultaneous removal of 2,4-dinitrophenyl or 4-methoxytrityl and tert-butyl ester groups resulted in HS-PCL-b-PAA. The PCL backbone remained...... chromatography (SEC), nuclear magnetic resonance eR NMR) and infrared (FT IR) spectroscopy. The capacity of the resulting block copolymer in preparation of monolayer-protected gold nanoparticles has been examined by reduction of a gold salt in the presence of this macroligand under thiol-deficient conditions...

  12. Self-Assembly of Novel Amphiphilic 21-Arm, Star-Like Coil-Rod Diblock Copolymers at Interfaces

    Science.gov (United States)

    Lin, Zhiqun; Zhao, Lei; Pang, Xinchang; Feng, Chaowei

    2012-02-01

    A series of novel amphiphilic 21-arm, star-like diblock copolymers, poly(acrylic acid)-b-poly(3-hexylthiophene) (PAA-b-P3HT) based on β-cyclodextrin (β-CD) with well defined molecular architectures and ratio of two chemically distinct blocks were prepared, for the first time, via a combination of quasi-living Grignard metathesis method (GRIM), click reaction, and atom transfer radical polymerization (ATRP). The star-like PAA-b-P3HT diblock copolymers consist of hydrophilic coil-like PAA cores and hydrophobic rod-like P3HT shells with narrow molecular weight distribution and controllable molecular weight of each block. Owing to the compact structure, the amphiphilic star-like PAA-b-P3HT formed a unimolecular micelle. Vesicles based on these novel amphiphilic star-like, coil-rod diblock copolymers were readily produced at the oil/water interface by crosslinking hydrophilic coil-like PAA cores with a bifunctional crosslinker, ethylenediamine. They also self-assembled into a nanotubular structure at the air/water interface.

  13. Amphiphilic block copolymers as flexible membrane materials generating structural and functional mimics of green bacterial antenna complexes.

    Science.gov (United States)

    Collins, A M; Timlin, J A; Anthony, S M; Montaño, G A

    2016-08-11

    We describe the ability of a short-chain amphiphilic block copolymer to self-assemble to form an artificial supramolecular light-harvesting system. Specifically, we demonstrate that the 2.5 kDa, poly(ethylene oxide)-block-poly(butadiene) (PEO-b-PBD), exhibits sufficient morphological flexibility as a membrane material and enables generation of mimics of three-dimensional chlorosomes as well as supported membrane bilayers containing energy acceptors. This overall architecture replicates green bacterial light-harvesting function whereby these assemblies exhibit long-range order and three-dimensional morphology similar to native chlorosomes and are capable of energy transfer internally and to external acceptors, located in a supporting biomimetic polymer membrane. Unlike native green bacterial systems that use multiple lipids as a matrix to generate the appropriate environment for chlorosome assembly and function, the described system matrix is comprised entirely of a single polymer amphiphile. This work demonstrates the potential of short-chain amphiphilic block copolymers in generating self-assembled, bio-mimetic membrane architectures, and in doing so, generates scalable, spatial-energetic landscapes for photonic applications. Finally, the results presented provide evidence of minimal requirements to induce chlorosome-like organization and function. PMID:27481550

  14. Real-time monitoring of the penetration of amphiphilic acrylate copolymer in leather using a fluorescent copolymer as tracer.

    Science.gov (United States)

    Du, Jin-Xia; Shi, Lu; Peng, Bi-Yu

    2015-12-01

    A fluorescent tracer, poly (acrylic-co-stearyl acrylate-co-3-acryloyl fluorescein) [poly (AA-co-SA-co-Ac-Flu)], used for real-time monitoring the penetration of amphiphilic acrylate copolymer, poly (acrylic-co-stearyl acrylate) [poly (AA-co-SA)], in leather was synthesized by radical polymerization of acrylic, stearyl acrylate and fluorescent monomer, 3-acryloyl fluorescein (Ac-Flu). The structure, molecular weight, introduced fluorescent group content and fluorescent characteristics of the fluorescent tracer and target copolymer, amphiphilic acrylate copolymer, were also characterized. The results show that the tracer presents the similar structural characteristics to the target and enough fluorescence intensity with 1.68 wt % of the fluorescent monomer introduced amount. The vertical section of the leather treated with the target copolymer mixing with 7% of the tracer exhibits evident fluorescence, and the change of fluorescence intensity along with the vertical section with treating time increasing can reflect the penetration depth of the target copolymer. The introduction of the fluorescent group in polymer structure through copolymerization with a limited amount of fluorescent monomer, Ac-Flu, is an effective way to make a tracer to monitor the penetration of the target in leather, which provides a new thought for the penetration research of syntans such as vinyl copolymer materials in leather manufacture.

  15. Foams Stabilized by Tricationic Amphiphilic Surfactants

    OpenAIRE

    Heerschap, Seth; Marafino, John N.; McKenna, Kristin; Caran, Kevin L.; Feitosa, Klebert

    2015-01-01

    The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. Novel surfactant architectures with multi-cephalic and multi-tailed molecules have reportedly enhanced their anti-bacterial activity in connection with tail length and the nature of the head group, but their ability to produce and stabilize foam is mostly unknown. Here we report on experiments with tris-cationic, triple-headed, double- a...

  16. Amphiphilic Fullerenes for Biomedical and Optoelectronical Applications

    OpenAIRE

    Witte, Patrick

    2009-01-01

    Fullerenes have an enormous potential in applications to physics and biology. Specifically [60]fullerene with its unique electronic, optical and structural properties has attracted considerable attention for its application in biomedical materials and optoelectronic devices. In this context the selective functionalization of C60, which allows to combine the parent properties with new attributes like water-solubility or amphiphilicity is still a challenging topic for the synthetic chemist. In ...

  17. Prebiotic Lipidic Amphiphiles and Condensing Agents on the Early Earth

    OpenAIRE

    Michele Fiore; Peter Strazewski

    2016-01-01

    It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of ...

  18. Living Polymerization of N -Substituted β-Alanine N -Carboxyanhydrides: Kinetic Investigations and Preparation of an Amphiphilic Block Copoly-β-Peptoid

    KAUST Repository

    Grossmann, Arlett

    2012-07-03

    Poly(α-peptoid)s (N-substituted polyglycines) are interesting peptidomimetic biomaterials that have been discussed for many applications. Poly(β-peptoid)s (N-substituted poly-β-alanines), although equally intriguing, have received much less attention. Here we present results that suggest that while N-substituted β-alanine N-carboxyanhydrides can undergo a living nucleophilic ring-opening polymerization, the solubility of poly(β-peptoid)s can be very poor, which contributes to the limited accessibility using other synthetic approaches. The living character of the polymerization was utilized for the preparation of the first polymerized amphiphilic block copoly-β-peptoid. Our results may open a new route towards highly defined functional poly(β-peptoid)s which could represent biomaterials. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Adsorption and Aqueous Lubricating Properties of Charged and Neutral Amphiphilic Diblock Copolymers at a Compliant, Hydrophobic Interface

    DEFF Research Database (Denmark)

    Røn, Troels; Javakhishvili, Irakli; Jankova Atanasova, Katja;

    2013-01-01

    We have investigated the adsorption and lubricating properties of neutral and charged amphiphilic diblock copolymers at a hydrophobic polydimethylsiloxane (PDMS) interface in an aqueous environment. The diblock copolymers consist of a hydrophilic block of either neutral poly(ethylene glycol) (PEG......) or negatively charged poly(acrylic acid) (PAA) and of a hydrophobic block of polystyrene (PS) or poly(2-methoxyethyl acrylate) (PMEA), thus generating PEG-b-X or PAA-b-X, where X block is either PS or PMEA. The molecular weight ratios were roughly 1:1 with each block ca. 5 kDa. Comparing the neutral PEG...... and charged PAA buoyant blocks with all other conditions identical, the former showed superior adsorption onto nonpolar, hydrophobic PDMS surfaces from a neutral aqueous solution. PEGbased copolymers showed substantial adsorption for both PS and PMEA as the anchoring block, whereas PAA-based copolymers showed...

  20. Fluctuations and structure of amphiphilic films; Fluctuations et structure de films d`amphiphiles

    Energy Technology Data Exchange (ETDEWEB)

    Gourier, CH

    1996-07-01

    This thesis is divided in three parts.The first part exposes in a theoretical point of view, how the fluctuations spectrum of an amphiphilic film is governed by its properties and its bidimensional characteristics.The measurements of fluctuations spectra of an interface are accessible with the measurement of intensity that interface diffuses out of the specular angle, we present in the second chapter the principles of the X rays diffusion by a real interface and see how the diffuse diffusion experiments allow to determine the fluctuations spectrum of an amphiphilic film. The second part is devoted to the different experimental techniques that have allowed to realize the study of fluctuation as well as the structural study.The third part is devoted to experimental results concerning the measurements of fluctuations spectra and to the study of the structure of amphiphilic films. We show that it is possible by using an intense source of X rays (ESRF: European Synchrotron Radiation Facility) to measure the water and amphiphilic films fluctuations spectra until molecular scales. The last chapter is devoted to the structural study and film fluctuations made of di-acetylenic molecules. (N.C.)

  1. Water Diffusion Dependence on Amphiphilic Block Design in (Amphiphilic-Hydrophobic) Diblock Copolymer Membranes.

    Science.gov (United States)

    Dorenbos, Gert

    2016-06-30

    Polyelectrolyte membranes (PEMs) are applied in polyelectrolyte fuel cells (PEFC). The proton conductive pathways within PEMs are provided by nanometer-sized water containing pores. Large-scale application of PEFC requires the production of low-cost membranes with high proton conductivity and therefore good connected pore networks. Pore network formation within four alternative model diblock (hydrophobic_amphiphilic) copolymers in the presence of water is studied by dissipative particle dynamics. Each hydrophobic block contains 50 consecutively connected hydrophobic (A) fragments, and amphiphilic blocks contain 40 hydrophobic A beads and 10 hydrophilic C beads. For one amphiphilic block the C beads are distributed uniformly along the backbone. For the other architectures C beads are located at the end of the side chains attached at regular intervals along the backbone. Water diffusion through the pores is modeled by Monte Carlo tracer diffusion through mapped morphologies. Diffusion is highest for the grafted architectures and increases with increase of length of the side chains. A consistent picture emerges in which diffusion strongly increases with the value of ⟨Nbond⟩ within the amphiphilic block, where ⟨Nbond⟩ is the average number of bonds between hydrophobic A beads and the nearest C bead. PMID:27266679

  2. Glucose-neopentyl glycol (GNG) amphiphiles for membrane protein study

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Rana, Rohini R; Gotfryd, Kamil;

    2013-01-01

    The development of a new class of surfactants for membrane protein manipulation, "GNG amphiphiles", is reported. These amphiphiles display promising behavior for membrane proteins, as demonstrated recently by the high resolution structure of a sodium-pumping pyrophosphatase reported by Kellosalo et...

  3. Amphiphile nanoarchitectonics: from basic physical chemistry to advanced applications.

    Science.gov (United States)

    Ramanathan, Muruganathan; Shrestha, Lok Kumar; Mori, Taizo; Ji, Qingmin; Hill, Jonathan P; Ariga, Katsuhiko

    2013-07-14

    Amphiphiles, either synthetic or natural, are structurally simple molecules with the unprecedented capacity to self-assemble into complex, hierarchical geometries in nanospace. Effective self-assembly processes of amphiphiles are often used to mimic biological systems, such as assembly of lipids and proteins, which has paved a way for bottom-up nanotechnology with bio-like advanced functions. Recent developments in nanostructure formation combine simple processes of assembly with the more advanced concept of nanoarchitectonics. In this perspective, we summarize research on self-assembly of amphiphilic molecules such as lipids, surfactants or block copolymers that are a focus of interest for many colloid, polymer, and materials scientists and which have become increasingly important in emerging nanotechnology and practical applications, latter of which are often accomplished by amphiphile-like polymers. Because the fundamental science of amphiphiles was initially developed for their solution assembly then transferred to assemblies on surfaces as a development of nanotechnological techniques, this perspective attempts to mirror this development by introducing solution systems and progressing to interfacial systems, which are roughly categorized as (i) basic properties of amphiphiles, (ii) self-assembly of amphiphiles in bulk phases, (iii) assembly on static surfaces, (iv) assembly at dynamic interfaces, and (v) advanced topics from simulation to application. This progression also represents the evolution of amphiphile science and technology from simple assemblies to advanced assemblies to nanoarchitectonics.

  4. Incorporation of Amphiphilic Cyclodextrins into Liposomes as Artificial Receptor Units

    NARCIS (Netherlands)

    Kauscher, Ulrike; Stuart, Marc C. A.; Druecker, Patrick; Galla, Hans-Joachim; Ravoo, Bart Jan

    2013-01-01

    In this article, we describe the introduction of amphiphilic beta-cyclodextrins into liposomes to act as artificial receptor units. Using dynamic light scattering, dye encapsulation, and cryogenic transmission electron microscopy, we show that amphiphilic beta-cyclodextrins can be mixed in any propo

  5. New Phase Transfer Agent for Dye:Application for Hyperbranched Poly(ester-amine)

    Institute of Scientific and Technical Information of China (English)

    Teng QIU; Li Ming TANG; Xin Lin TUO; De Shan LIU

    2004-01-01

    Hydrophilic hyperbranched poly(ester-amine) (HPEA) synthesized from diethanolamine and methyl acrylate was used as phase transfer agent for the first time to transfer methyl orange (MO) from water into chloroform.This process was quantified by UV-Vis spectra.A possible mechanism was put forward based on the formation of amphiphilic aggregates.

  6. Aqueous Foam Stabilized by Tricationic Amphiphilic Surfactants

    Science.gov (United States)

    Heerschap, Seth; Marafino, John; McKenna, Kristin; Caran, Kevin; Feitosa, Klebert; Kevin Caran's Research Group Collaboration

    2015-03-01

    The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. The development of novel architectures with multi-cephalic/tailed molecules have enhanced their anti-bacterial activity in connection with tail length and the nature of the head group. Here we report on the foamability of two triple head double, tail cationic surfactants (M-1,14,14, M-P, 14,14) and a triple head single tail cationic surfactant (M-1,1,14) and compare them with commercially available single headed, single tailed anionic and cationic surfactants (SDS,CTAB and DTAB). The results show that bubble rupture rate decrease with the length of the carbon chain irrespective of head structure. The growth rate of bubbles with short tailed surfactants (SDS) and longer, single tailed tricationic surfactants (M-1,1,14) was shown to be twice as high as those with longer tailed surfactants (CTAB, M-P,14,14, M-1,14,14). This fact was related to the size variation of bubbles, where the foams made with short tail surfactants exhibited higher polydispersivity than those with short tails. This suggests that foams with tricationic amphiphilics are closed linked to their tail length and generally insensitive to their head structure.

  7. Nonionic amphiphile nanoarchitectonics: self-assembly into micelles and lyotropic liquid crystals

    Science.gov (United States)

    Shrestha, Lok Kumar; Strzelczyk, Karolina Maria; Goswami Shrestha, Rekha; Ichikawa, Kotoko; Aramaki, Kenji; Hill, Jonathan P.; Ariga, Katsuhiko

    2015-05-01

    Amphiphiles, molecules that possess both hydrophilic and hydrophobic moieties, are architecturally simple molecules that can spontaneously self-assemble into complex hierarchical structures from lower to higher dimensions either in the bulk phase or at an interface. Recent developments in multifunctional nanostructure design using the advanced concept of nanoarchitectonics utilize this simple process of assembly. Amphiphilic self-assemblies involving lipids or proteins mimic the structure of biological systems, thus highlighting the necessity of a fundamental physical understanding of amphiphilic self-assembly towards a realization of the complex mechanisms operating in nature. Herein, we describe self-assembled microstructures of biocompatible and biodegradable tetraglycerol lauryl ether (C12G4) nonionic surfactant in an aqueous solvent system. Temperature-composition analyses of equilibrium phases identified by using small-angle x-ray scattering (SAXS) provide strong evidence of various spontaneously self-assembled mesostructures, such as normal micelles (Wm), hexagonal liquid crystal (H1), and reverse micelles (Om). In contrast to conventional poly(oxyethylene) nonionic surfactants, C12G4 did not exhibit the clouding phenomenon at higher temperatures (phase separation was not observed up to 100 °C), demonstrating the greater thermal stability of the self-assembled mesophases. Generalized indirect Fourier transformation (GIFT) evaluation of the SAXS data confirmed the formation of core-shell-type spherical micelles with a maximum dimension ca. 8.7 nm. The shape and size of the C12G4 micelles remained apparently unchanged over a wide range of concentrations (up to 20%), but intermicellar interactions increased and could be described by the Percus-Yevick (PY) theory (after Carnahan and Starling), which provides a very accurate analytical expression for the osmotic pressure of a monodisperse hard sphere.

  8. The Behavior of Amphiphile at Oil-Water Interface by Monte Carlo Simulation

    Institute of Scientific and Technical Information of China (English)

    潘海华; 李啸风; 李浩然; 刘迪霞; 韩世钧

    2003-01-01

    A novel simple two-dimensional square-lattice model of amphiphile at oil-water interface is developed,in which oil and water act as solvent and occupy empty sites and amphiphile occupies chains of sites. In this model, the oil-water interface is fixed, And amphiphile molecules will be enriched at the oil-water interface. The interfacial concentration of amphiphile calculated by Monte Carlo method shows that it is easier for the hydrophilic-hydrophobic balanced amphiphile to stay at the interface. And the adsorption of amphiphile increases with the increase of amphiphile concentration and the decrease with temperature.

  9. MORPHOLOGICAL TRANSITION BETWEEN VESICLES AND TUBULES FOR A GLYCOPOLYMER-CONTAINING AMPHIPHILIC DIBLOCK COPOLYMER IN AQUEOUS SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    Zi-chen Li; Yue Shen; Yu-zeng Liang; Fu-mian Li

    2001-01-01

    The morphological transition of molecular assemblies in aqueous solutions for a new amphiphilic diblock copolymer induced by changing the initial solvent conditions was studied by transmission electron microscopy (TEM). The copolymer was polysryrene(77)-b-poly[2-(β-D-glucopyranosyloxy)ethyl acrylate (6)] (PSt77-b-PGEA6) and the solvent was a mixture of DMF and THF. PSt77-b-PGEA6 yields vesicles and tubules when it is initially dissolved in THF and DMF respectively. The morphological transition between vesicles and tubules can be achieved by simply varying the amounts of THF and DMF, or changing the temperature at which the aggregates were prepared.

  10. Methotrexate-Loaded Four-Arm Star Amphiphilic Block Copolymer Elicits CD8+ T Cell Response against a Highly Aggressive and Metastatic Experimental Lymphoma.

    Science.gov (United States)

    Hira, Sumit Kumar; Ramesh, Kalyan; Gupta, Uttam; Mitra, Kheyanath; Misra, Nira; Ray, Biswajit; Manna, Partha Pratim

    2015-09-16

    We have synthesized a well-defined four-arm star amphiphilic block copolymer [poly(DLLA)-b-poly(NVP)]4 [star-(PDLLA-b-PNVP)4] that consists of D,L-lactide (DLLA) and N-vinylpyrrolidone (NVP) via the combination of ring-opening polymerization (ROP) and xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization. Synthesis of the polymer was verified by 1H NMR spectroscopy and gel permeation chromatography (GPC). The amphiphilic four-arm star block copolymer forms spherical micelles in water as demonstrated by transmission electron microscopy (TEM) and 1H NMR spectroscopy. Pyrene acts as a probe to ascertain the critical micellar concentration (cmc) by using fluorescence spectroscopy. Methotrexate (MTX)-loaded polymeric micelles of star-(PDLLA15-b-PNVP10)4 amphiphilic block copolymer were prepared and characterized by fluorescence and TEM studies. Star-(PDLLA15-b-PNVP10)4 copolymer was found to be significantly effective with respect to inhibition of proliferation and lysis of human and murine lymphoma cells. The amphiphilic block copolymer causes cell death in parental and MTX-resistant Dalton lymphoma (DL) and Raji cells. The formulation does not cause hemolysis in red blood cells and is tolerant to lymphocytes compared to free MTX. Therapy with MTX-loaded star-(PDLLA15-b-PNVP10)4 amphiphilic block copolymer micelles prolongs the life span of animals with neoplasia by reducing the tumor load, preventing metastasis and augmenting CD8+ T cell-mediated adaptive immune responses. PMID:26323031

  11. Synthesis of poly[methyl(3,3,3-trinuoropropyl)siloxane]b-poly(ethylene oxide)block copolymers

    Institute of Scientific and Technical Information of China (English)

    Xiao-li ZHAN; Bi CHEN; Qing-hua ZHANG; Ling-min YI; Bo JIANG; Feng-qiu CHEN

    2008-01-01

    A series of new amphiphilic poly[methyl(3,3,3-trifluoropropyl)siloxane]-b -poly(ethylene oxide)(PMTFPS-b-PEO)diblock copolymers with different ratios of hydrophobic segment to hydrophilic segment were prepared by coupling reactions of end-functional PMTFPS and PEO homopolymers.Copolymers were shown to be well defined and narrow molecular weight distribution(MWD)(1.07~1.3)by characterizations such as gel permeation chromatography(GPC)and 1H-nudear magnetic resonance(1H-NMR).

  12. Amphiphile nanoarchitectonics: from basic physical chemistry to advanced applications

    Energy Technology Data Exchange (ETDEWEB)

    Ramanathan, Nathan Muruganathan [ORNL; Shrestha, Lok Kumar [International Center for Materials Nanoarchitectonics (MANA); Mori, Taizo [International Center for Materials Nanoarchitectonics (MANA); Ji, Dr. Qingmin [National Institute for Materials Science, Tsukuba, Japan; Hill, Dr. Jonathan P [National Institute for Materials Science, Tsukuba, Japan; Ariga, Katsuhiko [National Institute for Materials Science, Tsukuba, Japan

    2013-01-01

    Amphiphiles, either synthetic or natural, are structurally simple molecules with the unprecedented capacity to self-assemble into complex, hierarchical geometries in nanospace. Effective self-assembly processes of amphiphiles are often used to mimic biological systems, such as, assembly of lipids and proteins, which has paved a way for bottom-up nanotechnology with bio-like advanced functions. Recent developments on nanostructure formation combine simple processes of assembly with the more advanced concept of nanoarchitectonics. In this pespective, we summarize research on self-assembly of amphiphilic molecules such as lipids, surfactants or block copolymers that are a focus of interest for many colloid, polymer, and materials scientists and which have become increasingly important in emerging nanotechnology. Because the fundamental science of amphiphiles was initially developed for their solution assembly then transferred to assemblies on surfaces as a development of nanotechnological technique, this perspective attempts to mirro this development by introducing solution systems and progressing to interfacial systems, which are roughly categorized as (i) basic properties of amphiphiles, (ii) self-assembly of amphiphiles in bulk phases, (iii) assembly on static surfaces, (iv) assembly at dynamic interfaces, and (v) advanced topics from simulation to application. This progression also represents the evolution of amphiphile science and technology from simple assemblies to advanced assemblies to nanoarchitectonics.

  13. Resilient self-assembling hydrogels from block copolypeptide amphiphiles

    Science.gov (United States)

    Nowak, Andrew Paul

    The ability to produce well defined synthetic polypeptides has been greatly improved by the discovery of transition metal species that mediate the controlled polymerization of N-carboxyanhydrides (NCAs). These metal species create a living polymerization system by producing control over chain length, low polydispersities, and the ability to form complex block architectures. We have applied this system to the synthesis of block copolypeptide amphiphiles. Initial block copolymers synthesized were composed of hydrophilic, cationic poly(L-Lysine) combined with hydrophobic, alpha-helical poly(L-Leucine). These Lysine- block-Leucine copolypeptides were found to form stiff, clear hydrogels at low concentration (˜1 wt%) in low ionic strength water. Based on this unexpected result we used the flexibility of our transition metal polymerization chemistry to better understand the nature and mechanisms of gel formation in these materials. Systematic changes to the original Lysine-block-Leucine copolypeptides were made by altering overall chain size, relative block length, polyelectrolyte charge, and hydrophobic secondary structure. Rheological characterization revealed that the strength of these hydrogels was primarily dependent on degree of polymerization, relative block length, and a well ordered secondary structure in the hydrophobic segment. The Lysine-block-Leucine hydrogels were formed by direct addition of water to dry polypeptide material which swelled to homogeneously fill the entire volume of liquid with no special processing. CryoTEM showed a percolating cellular network at ˜100nm that appears to be comprised of both membranes and fibers. Larger length scales studied with Laser Scanning Confocal Microscopy revealed a spontaneously formed microporous network with large (˜10mum) water rich voids. These hydrogels also displayed interesting mechanical properties including rapid recovery of solid like behavior after being sheared to a liquid and mechanical stability

  14. Poly (ethylene oxide)-block-poly (n-butyl acrylate)-blockpoly (acrylic acid) triblock terpolymers with highly asymmetric hydrophilic blocks: synthesis and aqueous solution properties

    OpenAIRE

    Petrov, P; Yoncheva, K. (Krassimira); Mokreva, P. (Pavlina); Konstantinov, S.; J M Irache; Müller, A.H.E. (Axel H.E.)

    2013-01-01

    The synthesis and aggregation behaviour in aqueous media of novel amphiphilic poly(ethylene oxide)- block-poly(n-butyl acrylate)-block-poly(acrylic acid) (PEO–PnBA–PAA) triblock terpolymers were studied. Terpolymers composed of two highly asymmetric hydrophilic PEO (113 monomer units) and PAA (10–17 units) blocks, and a longer soft hydrophobic PnBA block (163 or 223 units) were synthesized by atom transfer radical polymerisation (ATRP) of n-butyl acrylate and tert-butyl acrylate ...

  15. Preparation of pH-responsive membranes with amphiphilic copolymers by surface segregation method☆

    Institute of Scientific and Technical Information of China (English)

    Yanlei Su; Yuan Liu; Xueting Zhao; Yafei Li; Zhongyi Jiang

    2015-01-01

    Novel pH-responsive membranes were prepared by blending pH-responsive amphiphilic copolymers with pol-yethersulfone (PES) via a nonsolvent-induced phase separation (NIPS) technique. The amphiphilic copolymers bearing Pluronic F127 and poly(methacrylic acid) (PMAA) segments, abbreviated as PMAAn–F127–PMAAn, were synthesized by free radical polymerization. The physical and chemical properties of the blend membranes were evaluated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrum, water con-tact angle, Zeta potential and X-ray photoelectron spectroscopy (XPS). The enrichment of hydrophilic PMAA seg-ments on the membrane surfaces was attributed to surface segregation during the membrane preparation process. The blend membranes had significant pH-responsive properties due to the conformational changes of surface-segregated PMAA segments under different pH values of feed solutions. Fluxes of the blend membranes were larger at low pH values of feed solutions than that at high pH values. The pH-responsive ability of the mem-branes was enhanced with the increase of the degree of PMAA near-surface coverage.

  16. Amphiphilic nanocapsules entangled with organometallic coordination polymers for controlled cargo release.

    Science.gov (United States)

    Liang, Guodong; Ni, Huan; Bao, Suping; Zhu, Fangming; Gao, Haiyang; Wu, Qing; Tang, Ben Zhong

    2014-06-01

    A class of new amphiphilic nanocapsules entangled with organometallic coordination polymers has been developed for the first time. Poly(2-(N,N-dimethyl amino)ethyl methacrylate)-b-polystyrene capped with β-cyclodextrin (β-CD) (CD-PDMAEMA-b-PS) is first synthesized using sequent RAFT polymerization of styrene and 2-(N,N-dimethyl amino)ethyl methacrylate with xanthate modified β-CD as chain transfer agent. The end group of β-CD is allowed to include 4,4'-bipyridine through host-guest inclusion to yield PDMAEMA-b-PS terminated with an inclusion complex of β-CD and bipyridine (bpy-PDMAEMA-b-PS), which is then used as surfactant to prepare emulsion droplets in toluene/water mixture. Upon addition of Ni(II), bipyridine coordinates with Ni(II) to form coordination polymers in the periphery of emulsion droplets, affording amphiphilic capsules entangled with organometallic coordination polymers, as confirmed by GPC, (1)H NMR, SEM, TEM, DLS, and so on. The organometallic coordination polymer capsules are capable of encapsulating organic cargoes. Interestingly, encapsulated cargoes can be extracted from the capsules without damaging the capsules. Such capsules are potential candidates for encapsulating and controlled release of organic cargoes. PMID:24828951

  17. The non-peptidic part determines the internalization mechanism and intracellular trafficking of peptide amphiphiles.

    Directory of Open Access Journals (Sweden)

    Dimitris Missirlis

    Full Text Available BACKGROUND: Peptide amphiphiles (PAs are a class of amphiphilic molecules able to self-assemble into nanomaterials that have shown efficient in vivo targeted delivery. Understanding the interactions of PAs with cells and the mechanisms of their internalization and intracellular trafficking is critical in their further development for therapeutic delivery applications. METHODOLOGY/PRINCIPAL FINDINGS: PAs of a novel, cell- and tissue-penetrating peptide were synthesized possessing two different lipophilic tail architectures and their interactions with prostate cancer cells were studied in vitro. Cell uptake of peptides was greatly enhanced post-modification. Internalization occurred via lipid-raft mediated endocytosis and was common for the two analogs studied. On the contrary, we identified the non-peptidic part as the determining factor of differences between intracellular trafficking and retention of PAs. PAs composed of di-stearyl lipid tails linked through poly(ethylene glycol to the peptide exhibited higher exocytosis rates and employed different recycling pathways compared to ones consisting of di-palmitic-coupled peptides. As a result, cell association of the former PAs decreased with time. CONCLUSIONS/SIGNIFICANCE: Control over peptide intracellular localization and retention is possible by appropriate modification with synthetic hydrophobic tails. We propose this as a strategy to design improved peptide-based delivery systems.

  18. Dynamic Ordering Transitions of Liquid Crystals Driven by Interfacial Complexes Formed Between Polyanions and Amphiphilic Polyamines

    Science.gov (United States)

    Kinsinger, Michael I.; Buck, Maren E.; Campos, Fernando

    2011-01-01

    We report the design of an amphiphilic polyamine based on poly(2-alkenyl azlactone) (polymer 1) that strongly couples the formation of polyelectrolyte complexes at aqueous/liquid crystal (LC) interfaces to ordering transitions in the LC. We demonstrate that the addition of a strong anionic polyelectrolyte to aqueous solutions in contact with polymer 1-laden LC interfaces (prepared by Langmuir-Schaefer transfer of monolayers of polymer 1 onto micrometer-thick films of nematic LC) triggers ordering transitions in the LCs. We further demonstrate that changes in the ordering of the LCs (i) are driven by electrostatic interactions between the polyelectrolytes, (ii) involve multivalent interactions between the polyelectrolytes, and (iii) are triggered by reorganization of the hydrophobic side chains of amphiphilic polymer 1 upon formation of the interfacial complexes. The results presented in this paper lead us to conclude that ordering transitions in LCs can be used to provide insights into the structure and dynamics of interfacial complexes formed between polyelectrolytes. PMID:18991416

  19. THE AMPHIPHILIC MULTIARM COPOLYMERS BASED ON HYPERBRANCHED POLYESTER AND LYSINE: SYNTHESIS AND SELF-ASSEMBLY

    Institute of Scientific and Technical Information of China (English)

    Jing Wang; Yuan Yao; Bing Ji; Wei Huang; Yong-feng Zhou; De-yue Yan

    2011-01-01

    The amphiphilic multiarm copolymers were synthesized through the modification of commercially available hyperbranched polyesters (Boltom H40) with N-ε-carbobenzoxy-L-Lysine N-carboxyanhydride (ZLys-NCA). After being condensed with N-Boc-phenylalanine (Boc-NPhe) and deprotected the Boc-groups in trifluoroacetic acid (TFA), the original terminal hydroxyl groups were transformed into the amino groups and then initiated the ring-opening polymerization of ZLys-NCA. The hydrophilic poly(L-lysine) was grafted to the surface of Boltorn H40 successfully after the protecting benzyl groups were removed by the HBr solution in glacial acetic acid (33 wt%). The resulting multiarm copolymers were characterized by the 1H-NMR, GPC and FTIR. The arm length calculated by NMR and GPC analysis was about 3 and 13 lysine-units for H40-Phe-PLysl and H40-Phe-PLys2 respectively. Due to the amphiphilic molecular structure, they displayed ability to self-assemble into spherical micelles in aqueous solution with the average diameter in the range from 70 nm to 250 nm. The CMC of H40-Phe-PLysl and H40-Phe-PLys2 was 0.013 mg/mL and 0.028 mg/mL, respectively,indicating that H40-Phe-PLysl with shorter arm length is easier to self-assemble than H40-Phe-PLys2 with longer arm length.

  20. NOVEL AMPHIPHILIC FLUORESCENT GRAFT COPOLYMER: SYNTHESIS,CHARACTERIZATION AND ENCAPSULATION OF A HYDROPHOBIC AGENT

    Institute of Scientific and Technical Information of China (English)

    Zhao-qiang Wu; Shu Yang; Wen-yan Liao; Ling-zhi Meng

    2006-01-01

    Novel amphiphilic fluorescent graft copolymer (PVP-PyAHy) was successfully synthesized by the free radical copolymerization of hydrophobic monomer N-(1-pyrenebutyryl)-N'-acryloyl hydrazide (PyAHy) with hydrophilic precursor polymers of vinyl-functionalized poly(N-vinylpyrrolidone) (PVP) in DMF. The copolymer is amphiphilic and has intrinsic fluorescence. FT-IR, 1H-NMR, TEM, gel permeation chromatography-multi-angle laser light scattering, UV-Vis spectroscopy and fluorescence spectroscopy were used to characterize this copolymer. The TEM observation shows that the copolymer PVP-PyAHy forms micelles in aqueous solution. Results of fluorometric measurements illustrate that the critical micelle concentration (CMC) value of PVP-PyAHy in aqueous solution is about 0.90 mg/mL. To examine the encapsulation ability of the copolymer in aqueous media, methyl yellow was employed as a model hydrophobic agent. The loading level of the polymer to methyl yellow is 8.8 mg/g. The cytotoxicity assays for Madin Darby Canine Kidney (MDCK) cells shows good biocompatibility of PVP-PyAHy in vitro. These results suggest the potential of this copolymer PVP-PyAHy as drugs delivery carrier and fluorescent tracer.

  1. Development of controlled release formulations of imidacloprid employing novel nano-ranged amphiphilic polymers.

    Science.gov (United States)

    Adak, Totan; Kumar, Jitendra; Shakil, N A; Walia, S

    2012-01-01

    Amphiphilic copolymers, synthesized from poly (ethylene glycols) and various aliphatic diacids, which self assemble into nano-micellar aggregates in aqueous media, were used to develop controlled release (CR) formulations of imidacloprid [1-(6 chloro-3-pyridinyl methyl)-N-nitro imidazolidin-2-ylideneamine] using encapsulation technique. High solubilisation power and low critical micelle concentration (CMC) of these amphiphilic polymers may increase the efficacy of formulations. Formulations were characterised by Infrared (IR) spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscope (TEM). Encapsulation efficiency, loading capacity and stability after accelerated storage test of the developed formulations were checked. The kinetics of imidacloprid release in water from the different formulations was studied. Release from the commercial formulation was faster than the CR formulations. The diffusion exponent (n value) of imidacloprid, in water ranged from 0.22 to 0.37 in the tested formulations. While the time taken for release of 50 % of imidacloprid ranged from 2.32 to 9.31 days for the CR formulations. The developed CR formulations can be used for efficient pest management in different crops. PMID:22375594

  2. Polydispersity-Driven Block Copolymer Amphiphile Self-Assembly into Prolate-Spheroid Micelles

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Andrew L.; Repollet-Pedrosa, Milton H.; Mahanthappa, Mahesh K. (UW)

    2013-09-26

    The aqueous self-assembly behavior of polydisperse poly(ethylene oxide-b-1,4-butadiene-b-ethylene oxide) (OBO) macromolecular triblock amphiphiles is examined to discern the implications of continuous polydispersity in the hydrophobic block on the resulting aqueous micellar morphologies of otherwise monodisperse polymer surfactants. The chain length polydispersity and implicit composition polydispersity of these samples furnishes a distribution of preferred interfacial curvatures, resulting in dilute aqueous block copolymer dispersions exhibiting coexisting spherical and rod-like micelles with vesicles in a single sample with a O weight fraction, w{sub O}, of 0.18. At higher w{sub O} = 0.51-0.68, the peak in the interfacial curvature distribution shifts and we observe the formation of only American football-shaped micelles. We rationalize the formation of these anisotropically shaped aggregates based on the intrinsic distribution of preferred curvatures adopted by the polydisperse copolymer amphiphiles and on the relief of core block chain stretching by chain-length-dependent intramicellar segregation.

  3. Aggregation and self-assembly of amphiphilic block copolymers in aqueous dispersions of carbon nanotubes.

    Science.gov (United States)

    Shvartzman-Cohen, Rina; Florent, Marc; Goldfarb, Daniella; Szleifer, Igal; Yerushalmi-Rozen, Rachel

    2008-05-01

    The self-assembly (SA) of amphiphilic block copolymers (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)) was investigated in dispersions of single-walled and multiwalled carbon nanotubes (SWNT and MWNT, respectively) as a function of temperature. Differential scanning calorimetry (DSC) was used for characterization of the thermal behavior of the combined polymers-nanostructures system, and spin-probe electron paramagnetic resonance (EPR) was employed for probing the local dynamic and polarity of the polymer chains in the presence of nanostructures. It was found that SWNT and MWNT modify the temperature, enthalpy, and dynamic behavior of polymer SA. In particular, SWNT were found to increase the cooperativity of aggregating chains and dominate aggregate dynamics. MWNT reduced the cooperativity, while colloidal carbon black additives, studied for comparison, did not show similar effects. The experimental observations are consistent with the suggestion that dimensional matching between the characteristic radius of the solvated polymer chains and the dimensions of additives dominate polymer SA in the hybrid system. PMID:18355098

  4. Facile synthesis and characterization of novel biodegradable amphiphilic block copolymers bearing pendant hydroxyl groups

    International Nuclear Information System (INIS)

    Novel amphiphilic block copolymers bearing pendant hydroxyl groups polylactide-b–poly(3,3-bis(Hydroxymethyl–triazolylmethyl) oxetane)-b–polylactide (PLA-b–PHMTYO-b–PLA) were synthesized via a facile and efficient method. First, the block copolymer intermediates polylactide-b–poly(3,3-Diazidomethyloxetane)-b–polylactide (PLA-b–PBAMO-b–PLA) were synthesized through ring-opening polymerization of lactide using PBAMO as a macroinitiator. Following “Click” reaction of PLA-b–PBAMO-b–PLA with propargyl alcohol provided the targeted amphiphilic block copolymers PLA-b–PHMTYO-b–PLA with pendant hydroxyl groups. The composition and structure of prepared copolymers were characterized by 1H nuclear magnetic resonance (1H NMR) spectroscopy, Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behavior of the copolymers in water was investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and static light scattering (SLS). The results showed that the novel copolymers PLA-b–PHMTYO-b–PLA self-assembled into spherical micelles with diameters ranging from 100 nm to 200 nm in aqueous solution. These copolymers also exhibited low critical micellar concentrations (CMC: 6.9 × 10−4 mg/mL and 3.9 × 10−5 mg/mL, respectively). In addition, the in vitro cytotoxicity of these copolymers was determined in the presence of L929 cells. The results showed that the block copolymers PLA-b–PHMTYO-b–PLA exhibited better biocompatibility. Therefore, these well-defined copolymers are expected to find some applications in drug delivery or tissue engineering. - Highlights: • The method to synthesize PLA-b–PHMTYO-b–PLA is relatively facile and efficient. • PLA-b–PHMTYO-b–PLA self-assembles into spherical micelles with low CMC in water. • PLA-b–PHMTYO-b–PLA exhibits better biocompatibility and biodegradability

  5. Facile synthesis and characterization of novel biodegradable amphiphilic block copolymers bearing pendant hydroxyl groups.

    Science.gov (United States)

    Hu, Gaicen; Fan, Xiaoshan; Xu, Bingcan; Zhang, Delong; Hu, Zhiguo

    2014-10-01

    Novel amphiphilic block copolymers bearing pendant hydroxyl groups polylactide-b-poly(3,3-bis(Hydroxymethyl-triazolylmethyl) oxetane)-b-polylactide (PLA-b-PHMTYO-b-PLA) were synthesized via a facile and efficient method. First, the block copolymer intermediates polylactide-b-poly(3,3-Diazidomethyloxetane)-b-polylactide (PLA-b-PBAMO-b-PLA) were synthesized through ring-opening polymerization of lactide using PBAMO as a macroinitiator. Following "Click" reaction of PLA-b-PBAMO-b-PLA with propargyl alcohol provided the targeted amphiphilic block copolymers PLA-b-PHMTYO-b-PLA with pendant hydroxyl groups. The composition and structure of prepared copolymers were characterized by (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy, Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behavior of the copolymers in water was investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and static light scattering (SLS). The results showed that the novel copolymers PLA-b-PHMTYO-b-PLA self-assembled into spherical micelles with diameters ranging from 100 nm to 200 nm in aqueous solution. These copolymers also exhibited low critical micellar concentrations (CMC: 6.9 × 10(-4)mg/mL and 3.9 × 10(-5)mg/mL, respectively). In addition, the in vitro cytotoxicity of these copolymers was determined in the presence of L929 cells. The results showed that the block copolymers PLA-b-PHMTYO-b-PLA exhibited better biocompatibility. Therefore, these well-defined copolymers are expected to find some applications in drug delivery or tissue engineering. PMID:25175206

  6. Facile synthesis and characterization of novel biodegradable amphiphilic block copolymers bearing pendant hydroxyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Gaicen; Fan, Xiaoshan; Xu, Bingcan; Zhang, Delong; Hu, Zhiguo, E-mail: zghu@htu.cn

    2014-10-01

    Novel amphiphilic block copolymers bearing pendant hydroxyl groups polylactide-b–poly(3,3-bis(Hydroxymethyl–triazolylmethyl) oxetane)-b–polylactide (PLA-b–PHMTYO-b–PLA) were synthesized via a facile and efficient method. First, the block copolymer intermediates polylactide-b–poly(3,3-Diazidomethyloxetane)-b–polylactide (PLA-b–PBAMO-b–PLA) were synthesized through ring-opening polymerization of lactide using PBAMO as a macroinitiator. Following “Click” reaction of PLA-b–PBAMO-b–PLA with propargyl alcohol provided the targeted amphiphilic block copolymers PLA-b–PHMTYO-b–PLA with pendant hydroxyl groups. The composition and structure of prepared copolymers were characterized by {sup 1}H nuclear magnetic resonance ({sup 1}H NMR) spectroscopy, Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behavior of the copolymers in water was investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and static light scattering (SLS). The results showed that the novel copolymers PLA-b–PHMTYO-b–PLA self-assembled into spherical micelles with diameters ranging from 100 nm to 200 nm in aqueous solution. These copolymers also exhibited low critical micellar concentrations (CMC: 6.9 × 10{sup −4} mg/mL and 3.9 × 10{sup −5} mg/mL, respectively). In addition, the in vitro cytotoxicity of these copolymers was determined in the presence of L929 cells. The results showed that the block copolymers PLA-b–PHMTYO-b–PLA exhibited better biocompatibility. Therefore, these well-defined copolymers are expected to find some applications in drug delivery or tissue engineering. - Highlights: • The method to synthesize PLA-b–PHMTYO-b–PLA is relatively facile and efficient. • PLA-b–PHMTYO-b–PLA self-assembles into spherical micelles with low CMC in water. • PLA-b–PHMTYO-b–PLA exhibits better biocompatibility and biodegradability.

  7. Facially amphiphilic thiol capped gold and silver nanoparticles

    OpenAIRE

    Bhat, Shreedhar; Maitra, Uday

    2008-01-01

    A series of bile acid-derived facially amphiphilic thiols have been used to cap sliver and gold nanoparticles. The self-assembling properties of these steroid-capped nanoparticles have been investigated and reported in this article.

  8. Facially amphiphilic thiol capped gold and silver nanoparticles

    Indian Academy of Sciences (India)

    Shreedhar Bhata; Uday Maitra

    2008-11-01

    A series of bile acid-derived facially amphiphilic thiols have been used to cap sliver and gold nanoparticles. The self-assembling properties of these steroid-capped nanoparticles have been investigated and reported in this article.

  9. Amphiphilic Diblock Terpolymer PMAgala-b-P(MAA-co-MAChol)s with Attached Galactose and Cholesterol Grafts and Their Intracellular pH-Responsive Doxorubicin Delivery.

    Science.gov (United States)

    Wang, Zhao; Luo, Ting; Sheng, Ruilong; Li, Hui; Sun, Jingjing; Cao, Amin

    2016-01-11

    In this work, a series of diblock terpolymer poly(6-O-methacryloyl-D-galactopyranose)-b-poly(methacrylic acid-co-6-cholesteryloxy hexyl methacrylate) amphiphiles bearing attached galactose and cholesterol grafts denoted as the PMAgala-b-P(MAA-co-MAChol)s were designed and prepared, and these terpolymer amphiphiles were further exploited as a platform for intracellular doxorubicin (DOX) delivery. First, employing a sequential RAFT strategy with preliminarily synthesized poly(6-O-methacryloyl-1,2:3,4-di-O-isopropylidene-d-galactopyranose) (PMAIpGP) macro-RAFT initiator and a successive trifluoroacetic acid (TFA)-mediated deprotection, a series of amphiphilic diblock terpolymer PMAgala-b-P(MAA-co-MAChol)s were prepared, and were further characterized by NMR, Fourier transform infrared spectrometer (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and a dynamic contact angle testing instrument (DCAT). In aqueous media, spontaneous micellization of the synthesized diblock terpolymer amphiphiles were continuously examined by critical micellization concentration assay, dynamic light scattering (DLS), and transmission electron microscopy (TEM), and the efficacies of DOX loading by these copolymer micelles were investigated along with the complexed nanoparticle stability. Furthermore, in vitro DOX release of the drug-loaded terpolymer micelles were studied at 37 °C in buffer under various pH conditions, and cell toxicities of as-synthesized diblock amphiphiles were examined by MTT assay. Finally, with H1299 cells, intracellular DOX delivery and localization by the block amphiphile vectors were investigated by invert fluorescence microscopy. As a result, it was revealed that the random copolymerization of MAA and MAChol comonomers in the second block limited the formation of cholesterol liquid-crystal phase and enhanced DOX loading efficiency and complex nanoparticle stability, that ionic interactions between the DOX and MAA comonomer

  10. Rational design of purely peptidic amphiphiles for drug delivery applications

    OpenAIRE

    Bruyn Ouboter, Dirk de

    2011-01-01

    A broad range of new properties is emerging from supramolecular aggregates. Self-assembled structures of purely peptidic amphiphiles exploit these properties to produce biocompatible, biodegradable, smart materials for drug administration. This thesis explores the design, synthesis, purification, characterization of purely peptidic amphiphiles, and evaluates potential applications. The first chapter provides a general introduction to the field of self-assembly, and of drug delivery as com...

  11. Wetting in mixtures of water, nonionic amphiphiles, and nonpolar solvents

    Science.gov (United States)

    Kahlweit, M.; Busse, G.

    1989-07-01

    As is well known, medium- and long-chain alkanes do not spread across H2O-air interfaces, but shape a lens. In this paper it is shown that the same holds for the upper amphiphile-rich phase in binary H2O-amphiphile mixtures with medium- and long-chain nonionic amphiphiles that show a (closed) miscibility gap with water. This finding is somewhat unexpected because surfactants form monolayers at H2O-air interfaces which should facilitate the spreading of the amphiphile-rich phase. This wetting behavior corresponds to that in ternary H2O-oil-nonionic amphiphile mixtures with a three-phase body, in which the middle amphiphile-rich phase does not spread across the H2O-oil interface. The results may stimulate further studies on critical-point wetting [for a recent review see, e.g., S. Dietrich, in Phase Transitions and Critical Phenomena, edited by C. Domb and J. L. Lebowitz (Academic, London, 1988), Vol. 12, p. 1.], and may also help clarifying the properties of microemulsions [for a recent review see, e.g., M. Kahlweit, R. Strey, P. Firman, D. Haase, J. Jen, and R. Schomäcker, Langmuir 4, 499 (1988)].

  12. Revealing Amphiphilic Nanodornains of Anti-Biofouling Polymer Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Amadei, CA; Yang, R; Chiesa, M; Gleason, KK; Santos, S

    2014-04-09

    Undesired bacterial adhesion and biofilm formation on wetted surfaces leads to significant economic and environmental costs in various industries. Amphiphilic coatings with molecular hydrophilic and hydrophobic patches can mitigate such biofouling effectively in an environmentally friendly manner. The coatings are synthesized by copolymerizing (Hydroxyethyl)methacrylate and perfluorodecylacrylate via initiated chemical vapor deposition (iCVD). In previous studies, the size of the patches was estimated to be similar to 1.4-1.75 nm by fitting protein adsorption data to a theoretical model. However, no direct observations of the molecular heterogeneity exist and therefore the origin of the fouling resistance of amphiphilic coatings remains unclear. Here, the amphiphilic nature is investigated by amplitude modulation atomic force microscopy (AM-AFM). High-resolution images obtained by penetrating and oscillating the AFM tip under the naturally present water layer with sub-nanometer amplitudes reveal, for the first time, the existence of amphiphilic nanodomains (1-2 nm(2)). Compositional heterogeneity at the nanoscale is further corroborated by a statistical analysis on the data obtained with dynamic AM-AFM force spectroscopy. Variations in the long range attractive forces, responsible for water affinity, are also identified. These nanoscopic results on the polymers wettability are also confirmed by contact angle measurements (i.e., static and dynamic). The unprecedented ability to visualize the amphiphilic nanodomains as well as sub-nanometer crystalline structures provides strong evidence for the existence of previously postulated nanostructures, and sheds light on the underlying antifouling mechanism of amphiphilic chemistry.

  13. Synthesis and Characterization of Biodegradable Amphiphilic Star and Y-Shaped Block Copolymers as Potential Carriers for Vinorelbine

    Directory of Open Access Journals (Sweden)

    Fatemeh Bahadori

    2014-01-01

    Full Text Available Two amphiphilic block copolymers using hydrophobic poly(ε-caprolactone (PCL and hydrophilic poly(ethylene glycol (PEG were successfully synthesized. One of them is an (A-b-B4 type star polymer [(PCL-b-PEG4] and the other one is a Y-shaped PEG–(PCL2. A star-shaped polymer (PCL-b-PEG4 was prepared by ring-opening polymerization (ROP of ε-caprolactone continued by click reaction of (PCL-azide4 and PEG-alkyne. The synthesis of Y-shaped PEG–(PCL2 block copolymer was carried out via Diels-Alder click reaction of a furan protected maleimide end-functionalized PEG (PEG-MI with an anthracene end-functionalized PCL following the ROP of ε-caprolactone. The characterization of micelles is carried out using both materials in aqueous media as drug delivery vehicles, which showed satisfying results and enhanced the cytotoxic effect of the anti-cancer drug vinorelbine (VLB. However, micelles consisted of Y-shaped unimers were found to be more convenient for delivery of hydrophobic drugs such as VLB because they formed in lower concentration, carrying a higher amount of drugs and owing a monomodal distribution. We concluded that the free tails of hydrophobic chains in Y-shaped block copolymer facilitate the assembly of amphiphilic material in water to form micelles.

  14. Synthesis of biodegradable amphiphilic Y-shaped block co-polymers via ring-opening polymerization for drug delivery.

    Science.gov (United States)

    Jia, Lin; Yan, Lifeng; Li, Yang

    2011-01-01

    A series of novel Y-shaped biodegradable block co-polymers of poly(ε-caprolactone) (PCL) and poly(ethyl ethylene phosphate) (PEEP) (PCL-(PEEP)2) were synthesized via ring-opening polymerization (ROP) of EEP with bis-hydroxy-functional ROP initiator (init-PCL-(OH)2). The init-PCL-(OH)2 was synthesized by ROP of CL using 4-hydroxybutyl acrylate (HBA) as initiator and L-tartaric acid as catalyst in bulk, and subsequently the resulting vinyl-terminated PCL was end-capped by acetyl chloride, followed by Michael addition using excess diethanolamine. The Y-shaped co-polymers and their intermediates were characterized by (1)H-, (13)C-, (31)P-NMR, FT-IR and gel-permeation chromatography. The results indicated that the molecular weight of the Y-shaped co-polymers increased with the increasing of the molar ratios of EEP to init-PCL-(OH)2 in the feed, while the PCL chain length was kept constant. The amphiphilic block co-polymers could self-assemble into micelles in aqueous solution, which was demonstrated by dynamic light scattering, (1)H-NMR and atomic force microscopy. A study of controlled release of indomethacin indicated that the amphiphilic block co-polymers could potentially provide novel vehicles for drug delivery.

  15. Highly protein-resistant coatings and suspension cell culture thereon from amphiphilic block copolymers prepared by RAFT polymerization.

    Science.gov (United States)

    Haraguchi, Kazutoshi; Kubota, Kazuomi; Takada, Tetsuo; Mahara, Saori

    2014-06-01

    Novel amphiphilic block copolymers composed of hydrophobic (poly(2-methoxyethyl acrylate): M) and hydrophilic (poly(N,N-dimethylacrylamide): D) segments were synthesized by living radical polymerization: a reversible addition-fragmentation chain-transfer polymerization. Two types of amphiphilic block copolymers, triblock (MDM) and 4-arm block ((MD)4) copolymers with specific compositions (D/M = (750-1500)/250), were prepared by a versatile one-pot synthesis. These copolymers show good adhesion to various types of substrates (e.g., polystyrene, polycarbonate, polypropylene, Ti, and glass), and the surface coating showed high protein repellency and a low contact angle for water, regardless of the substrate. The two opposing characteristics of high protein repellency and good substrate adhesion were achieved by the combined effects of the molecular architecture of the block copolymers, the high molecular weight, and the characteristics of each segment, that is, low protein adsorption capability of both segments and low glass transition temperature of the hydrophobic segment. Further, a polystyrene dish coated with the MDM block copolymer could be sterilized by γ-ray irradiation and used as a good substrate for a suspension cell culture that exhibits low cell adhesion and good cell growth.

  16. Highly protein-resistant coatings and suspension cell culture thereon from amphiphilic block copolymers prepared by RAFT polymerization.

    Science.gov (United States)

    Haraguchi, Kazutoshi; Kubota, Kazuomi; Takada, Tetsuo; Mahara, Saori

    2014-06-01

    Novel amphiphilic block copolymers composed of hydrophobic (poly(2-methoxyethyl acrylate): M) and hydrophilic (poly(N,N-dimethylacrylamide): D) segments were synthesized by living radical polymerization: a reversible addition-fragmentation chain-transfer polymerization. Two types of amphiphilic block copolymers, triblock (MDM) and 4-arm block ((MD)4) copolymers with specific compositions (D/M = (750-1500)/250), were prepared by a versatile one-pot synthesis. These copolymers show good adhesion to various types of substrates (e.g., polystyrene, polycarbonate, polypropylene, Ti, and glass), and the surface coating showed high protein repellency and a low contact angle for water, regardless of the substrate. The two opposing characteristics of high protein repellency and good substrate adhesion were achieved by the combined effects of the molecular architecture of the block copolymers, the high molecular weight, and the characteristics of each segment, that is, low protein adsorption capability of both segments and low glass transition temperature of the hydrophobic segment. Further, a polystyrene dish coated with the MDM block copolymer could be sterilized by γ-ray irradiation and used as a good substrate for a suspension cell culture that exhibits low cell adhesion and good cell growth. PMID:24773089

  17. Improved insulin loading in poly (lactic-co-glycolic) acid (PLGA) nanoparticles upon self-assembly with lipids

    DEFF Research Database (Denmark)

    Garcia Diaz, Maria; Foged, Camilla; Nielsen, Hanne Mørck

    2015-01-01

    of insulin into poly(lactic-co-glycolic) acid (PLGA) nanoparticles by pre-assembly with amphiphilic lipids. Insulin was complexed with soybean phosphatidylcholine or sodium caprate by self-assembly and subsequently loaded into PLGA nanoparticles by using the double emulsion-solvent evaporation technique...

  18. Poly(ester amide-Poly(ethylene oxide Graft Copolymers: Towards Micellar Drug Delivery Vehicles

    Directory of Open Access Journals (Sweden)

    Gregory J. Zilinskas

    2012-01-01

    Full Text Available Micelles formed from amphiphilic copolymers are promising materials for the delivery of drug molecules, potentially leading to enhanced biological properties and efficacy. In this work, new poly(ester amide-poly(ethylene oxide (PEA-PEO graft copolymers were synthesized and their assembly into micelles in aqueous solution was investigated. It was possible to tune the sizes of the micelles by varying the PEO content of the polymers and the method of micelle preparation. Under optimized conditions, it was possible to obtain micelles with diameters less than 100 nm as measured by dynamic light scattering and transmission electron microscopy. These micelles were demonstrated to encapsulate and release a model drug, Nile Red, and were nontoxic to HeLa cells as measured by an MTT assay. Overall, the properties of these micelles suggest that they are promising new materials for drug delivery systems.

  19. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment

    DEFF Research Database (Denmark)

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C.;

    2016-01-01

    Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD) library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We the...... of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy...... then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients...... with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any...

  20. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment

    Directory of Open Access Journals (Sweden)

    Anne-Marie Ellegaard

    2016-07-01

    Full Text Available Non-small cell lung cancer (NSCLC is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any non-localized cancer, and ebastine use showed a similar tendency. The association between CAD antihistamine use and reduced mortality was stronger among patients with records of concurrent chemotherapy than among those without such records. In line with this, sub-micromolar concentrations of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy.

  1. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment.

    Science.gov (United States)

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C; Anand, Atul; Cederkvist, Luise; Petersen, Nikolaj H T; Nylandsted, Jesper; Stenvang, Jan; Mellemgaard, Anders; Østerlind, Kell; Friis, Søren; Jäättelä, Marja

    2016-07-01

    Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD) library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any non-localized cancer, and ebastine use showed a similar tendency. The association between CAD antihistamine use and reduced mortality was stronger among patients with records of concurrent chemotherapy than among those without such records. In line with this, sub-micromolar concentrations of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy. PMID:27333030

  2. Design of nanostructures based on aromatic peptide amphiphiles.

    Science.gov (United States)

    Fleming, Scott; Ulijn, Rein V

    2014-12-01

    Aromatic peptide amphiphiles are gaining popularity as building blocks for the bottom-up fabrication of nanomaterials, including gels. These materials combine the simplicity of small molecules with the versatility of peptides, with a range of applications proposed in biomedicine, nanotechnology, food science, cosmetics, etc. Despite their simplicity, a wide range of self-assembly behaviours have been described. Due to varying conditions and protocols used, care should be taken when attempting to directly compare results from the literature. In this review, we rationalise the structural features which govern the self-assembly of aromatic peptide amphiphiles by focusing on four segments, (i) the N-terminal aromatic component, (ii) linker segment, (iii) peptide sequence, and (iv) C-terminus. It is clear that the molecular structure of these components significantly influences the self-assembly process and resultant supramolecular architectures. A number of modes of assembly have been proposed, including parallel, antiparallel, and interlocked antiparallel stacking conformations. In addition, the co-assembly arrangements of aromatic peptide amphiphiles are reviewed. Overall, this review elucidates the structural trends and design rules that underpin the field of aromatic peptide amphiphile assembly, paving the way to a more rational design of nanomaterials based on aromatic peptide amphiphiles. PMID:25199102

  3. A new drug carrier: Magnetite nanoparticles coated with amphiphilic block copolymer

    Institute of Scientific and Technical Information of China (English)

    CHANG Yu; BAI YunPeng; TENG Bao; Li ZhaoLong

    2009-01-01

    This paper reports on the synthesis and characterization of 4 nm magnetite nanoparticles coated with amphiphilic block copolymers of poly(ethyl methacrylate)-b-poly(2-hydroxyethyl methacrylate) (PEMA-b-PHEMA) by surface-initiated atom transfer radical polymerization (ATRP), which can act as new po-tential carriers for hydrophobic targeted drug delivery. Vibrating sample magnetometer analysis indi-cated that the magnetite nanoparticles were superparamagnetic at room temperature. Thermogravim-etric analysis (TGA) was applied to studying the property of surface of magnetite nanoparticles, and the surface density of macromolecules was calculated. The grafting density of oleic acid, BrMPA and PEMA was 5.8, 3.9, 0.16 chain/nm2 respectively, which indicates that the initiation efficiency decreases due to the influence of large space of oleic acid molecules. In vitro progesterone and (-)-isoproterenol hy-drochloride release in phosphate buffered saline (PBS) at pH 7.0 and 37℃ was conducted in order to demonstrate the function of drug loading and release. The results showed that the amount of drug carried into the core-shell Fe3O4@PEMA-b-PHEMA depends on the length of hydrophobic segment of block copolymer. The release of progesterone (37% after 22 h in our previous work) was compared with the release of (-)-isoproterenol hydrochloride (80% after 50 min), demonstrating that the strong hy-drophobic interaction between hydrophobic segment and drug can effectively control the release of hydrophobic drugs.

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

    Science.gov (United States)

    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

  5. A New Class of Amphiphiles Bearing Rigid Hydrophobic Groups for Solubilization and Stabilization of Membrane Proteins

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Rasmussen, Søren G F; Rana, Rohini R;

    2012-01-01

    Non-traditional amphiphiles: Conferring aqueous solubility on membrane proteins generally requires the use of a detergent or other amphiphilic agent. A new class of amphiphiles was synthesized, based on steroidal lipophilic groups, and evaluated with several membrane proteins. The results show th...

  6. Redox-controllable amphiphilic [2]rotaxanes.

    Science.gov (United States)

    Tseng, Hsian-Rong; Vignon, Scott A; Celestre, Paul C; Perkins, Julie; Jeppesen, Jan O; Di Fabio, Alberto; Ballardini, Roberto; Gandolfi, M Teresa; Venturi, Margherita; Balzani, Vincenzo; Stoddart, J Fraser

    2004-01-01

    With the fabrication of molecular electronic devices (MEDs) and the construction of nanoelectromechanical systems (NEMSs) as incentives, two constitutionally isomeric, redox-controllable [2]rotaxanes have been synthesized and characterized in solution. Therein, they both behave as near-perfect molecular switches, that is, to all intents and purposes, these two rotaxanes can be switched precisely by applying appropriate redox stimuli between two distinct chemomechanical states. Their dumbbell-shaped components are composed of polyether chains interrupted along their lengths by i) two pi-electron rich recognition sites-a tetrathiafulvalene (TTF) unit and a 1,5-dioxynaphthalene (DNP) moiety-with ii) a rigid terphenylene spacer placed between the two recognition sites, and then terminated by iii) a hydrophobic tetraarylmethane stopper at one end and a hydrophilic dendritic stopper at the other end of the dumbbells, thus conferring amphiphilicity upon these molecules. A template-directed protocol produces a means to introduce the tetracationic cyclophane, cyclobis(paraquat-p-phenylene) (CBPQT(4+)), which contains two pi-electron accepting bipyridinium units, mechanically interlocked around the dumbbell-shaped components. Both the TTF unit and the DNP moiety are potential stations for CBPQT(4+), since they can establish charge-transfer and hydrogen bonding interactions with the bipyridinium units of the cyclophane, thereby introducing bistability into the [2]rotaxanes. In both constitutional isomers, (1)H NMR and absorption spectroscopies, together with electrochemical investigations, reveal that the CBPQT(4+) ring is predominantly located on the TTF unit, leading to the existence of a single translational isomer (co-conformation) in both cases. In addition, a model [2]rotaxane, incorporating hydrophobic tetraarylmethane stoppers at both ends of its dumbbell-shaped component, has also been synthesized as a point of reference. Molecular synthetic approaches were used to

  7. Magnetic Amphiphilic Composites Applied for the Treatment of Biodiesel Wastewaters

    Directory of Open Access Journals (Sweden)

    Bruno R. S. Lemos

    2012-05-01

    Full Text Available In this work, new magnetic amphiphilic composites were prepared by chemical vapor deposition with ethanol on the surface of hydrophilic natural chrysotile matrix containing Fe catalyst. XRD, Raman, Mössbauer and SEM analyses suggest the formation of a complex nanostructured material composed of hydrophobic carbon nanotubes/nanofibers grown on the hydrophilic surface of the MgSi fiber mineral and the presence of Fe metallic nanoparticles coated by carbon. These nanostructured particles show amphiphilic properties and interact very well with both oil and aqueous phases. When added to emulsions the amphiphilic particles locate on the oil/water interface and, under a magnetic field, the oil droplets collapsed leading to the separation of the aqueous and oil phases. Preliminary work showed excellent results on the use of these particles to break wastewater emulsions in the biodiesel process.

  8. Competitive Binding of Natural Amphiphiles with Graphene Derivatives

    Science.gov (United States)

    Radic, Slaven; Geitner, Nicholas K.; Podila, Ramakrishna; Käkinen, Aleksandr; Chen, Pengyu; Ke, Pu Chun; Ding, Feng

    2013-07-01

    Understanding the transformation of graphene derivatives by natural amphiphiles is essential for elucidating the biological and environmental implications of this emerging class of engineered nanomaterials. Using rapid discrete-molecular-dynamics simulations, we examined the binding of graphene and graphene oxide with peptides, fatty acids, and cellulose, and complemented our simulations by experimental studies of Raman spectroscopy, FTIR, and UV-Vis spectrophotometry. Specifically, we established a connection between the differential binding and the conformational flexibility, molecular geometry, and hydrocarbon content of the amphiphiles. Importantly, our dynamics simulations revealed a Vroman-like competitive binding of the amphiphiles for the graphene oxide substrate. This study provides a mechanistic basis for addressing the transformation, evolution, transport, biocompatibility, and toxicity of graphene derivatives in living systems and the natural environment.

  9. Amphiphilic polymeric micelle as pseudostationary phase in electrokinetic chromatography for analysis of eight corticosteroids in cosmetics.

    Science.gov (United States)

    Xu, Xiaojin; Ni, Xinjiong; Cao, Yuhua; Zhuo, Xiaolu; Yang, Xiaoxiao; Cao, Guangqun

    2014-03-01

    Amphiphilic polymeric micelle, as a novel pseudostationary phase in EKC was used to determine eight kinds of corticosteroids namely hydrocortisone, prednisolone, hydrocortisone acetate, prednisone, cortisone acetate, prednisolone acetate, dexamethasone, and triamcinolone acetonide in cosmetics. Amphiphilic random copolymer poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) was micellizated via neutralization in alkaline aqueous solution. The influences of the molar ratio of monomer MMA to MAA, the concentration of polymer and pH on the polymeric micelle microstructure and EKC performances were investigated. As molar ratio of MMA to MAA in P(MMA-co-MAA) increased, both CMC and environmental polarity of the inner core in polymeric micelle decreased dramatically. With increasing monomer ratio, the size of polymeric micelles increased firstly, and then decreased, finally increased again. ζ potential of the micelle had a slight decline trend. As increment of polymer concentration, the size of the polymeric micelle increased steadily. By optimizing the monomer ratio, the polymer concentration, and pH of the running buffer, as well as operation conditions such as separation voltage and temperature, the eight analytes could be separated within 16.5 min using 7.5 mg/mL polymer with the monomer ratio of 7:3 dissolved in pH 9.2 borax buffer as the running buffer. The method has been used for analysis of corticosteroids in cosmetic samples with simple extraction; the recoveries for eight analytes were between 85.9 and 106%. This method was of accuracy, repeatability, pretreatment simplicity, and could be applied to the quality control of cosmetics. PMID:24338855

  10. Amphiphilic polymeric micelle as pseudostationary phase in electrokinetic chromatography for analysis of eight corticosteroids in cosmetics.

    Science.gov (United States)

    Xu, Xiaojin; Ni, Xinjiong; Cao, Yuhua; Zhuo, Xiaolu; Yang, Xiaoxiao; Cao, Guangqun

    2014-03-01

    Amphiphilic polymeric micelle, as a novel pseudostationary phase in EKC was used to determine eight kinds of corticosteroids namely hydrocortisone, prednisolone, hydrocortisone acetate, prednisone, cortisone acetate, prednisolone acetate, dexamethasone, and triamcinolone acetonide in cosmetics. Amphiphilic random copolymer poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) was micellizated via neutralization in alkaline aqueous solution. The influences of the molar ratio of monomer MMA to MAA, the concentration of polymer and pH on the polymeric micelle microstructure and EKC performances were investigated. As molar ratio of MMA to MAA in P(MMA-co-MAA) increased, both CMC and environmental polarity of the inner core in polymeric micelle decreased dramatically. With increasing monomer ratio, the size of polymeric micelles increased firstly, and then decreased, finally increased again. ζ potential of the micelle had a slight decline trend. As increment of polymer concentration, the size of the polymeric micelle increased steadily. By optimizing the monomer ratio, the polymer concentration, and pH of the running buffer, as well as operation conditions such as separation voltage and temperature, the eight analytes could be separated within 16.5 min using 7.5 mg/mL polymer with the monomer ratio of 7:3 dissolved in pH 9.2 borax buffer as the running buffer. The method has been used for analysis of corticosteroids in cosmetic samples with simple extraction; the recoveries for eight analytes were between 85.9 and 106%. This method was of accuracy, repeatability, pretreatment simplicity, and could be applied to the quality control of cosmetics.

  11. Screening nylon-3 polymers, a new class of cationic amphiphiles, for siRNA delivery.

    Science.gov (United States)

    Nadithe, Venkatareddy; Liu, Runhui; Killinger, Bryan A; Movassaghian, Sara; Kim, Na Hyung; Moszczynska, Anna B; Masters, Kristyn S; Gellman, Samuel H; Merkel, Olivia M

    2015-02-01

    Amphiphilic nucleic acid carriers have attracted strong interest. Three groups of nylon-3 copolymers (poly-β-peptides) possessing different cationic/hydrophobic content were evaluated as siRNA delivery agents in this study. Their ability to condense siRNA was determined in SYBR Gold assays. Their cytotoxicity was tested by MTT assays, their efficiency of delivering Alexa Fluor-488-labeled siRNA intracellularly in the presence and absence of uptake inhibitors was assessed by flow cytometry, and their transfection efficacies were studied by luciferase knockdown in a cell line stably expressing luciferase (H1299/Luc). Endosomal release was determined by confocal laser scanning microscopy and colocalization with lysotracker. All polymers efficiently condensed siRNA at nitrogen-to-phosphate (N/P) ratios of 5 or lower, as reflected in hydrodynamic diameters smaller than that at N/P 1. Although several formulations had negative zeta potentials at N/P 1, G2C and G2D polyplexes yielded >80% uptake in H1299/Luc cells, as determined by flow cytometry. Luciferase knockdown (20-65%) was observed after transfection with polyplexes made of the high molecular weight polymers that were the most hydrophobic. The ability of nylon-3 polymers to deliver siRNA intracellularly even at negative zeta potential implies that they mediate transport across cell membranes based on their amphiphilicity. The cellular uptake route was determined to strongly depend on the presence of cholesterol in the cell membrane. These polymers are, therefore, very promising for siRNA delivery at reduced surface charge and toxicity. Our study identified nylon-3 formulations at low N/P ratios for effective gene knockdown, indicating that nylon-3 polymers are a new, promising type of gene delivery agent. PMID:25437915

  12. Passive targeting of thermosensitive diblock copolymer micelles to the lungs: synthesis and characterization of poly(N-isopropylacrylamide)-block-poly(ε-caprolactone)

    OpenAIRE

    Lee, Ren-Shen; Lin, Chih-Hung; Aljuffali, Ibrahim A.; Hu, Kai-Yin; Fang, Jia-You

    2015-01-01

    Background Amphiphilic poly(N-isopropylacrylamide)-block-poly(ε-caprolactone) (PNiPAAm-b-PCL) copolymers were synthesized by ring-opening polymerization to form thermosensitive micelles as nanocarriers for bioimaging and carboplatin delivery. Results The critical micelle concentration increased from 1.8 to 3.5 mg/l following the decrease of the PNiPAAm chain length. The copolymers revealed a lower critical solution temperature (LCST) between 33 and 40°C. The copolymers self-assembled to form ...

  13. Cationic amphiphilic non-hemolytic polyacrylates with superior antibacterial activity.

    Science.gov (United States)

    Punia, Ashish; He, Edward; Lee, Kevin; Banerjee, Probal; Yang, Nan-Loh

    2014-07-01

    Acrylic copolymers with appropriate compositions of counits having cationic charge with 2-carbon and 6-carbon spacer arms can show superior antibacterial activities with concomitant very low hemolytic effect. These amphiphilic copolymers represent one of the most promising synthetic polymer antibacterial systems reported. PMID:24854366

  14. Langmuir monolayer formation of metal complexes from polymerizable amphiphilic ligands

    NARCIS (Netherlands)

    Werkman, PJ; Schouten, AJ

    1996-01-01

    The monolayer behaviour of 4-(10,12-pentacosadiynoicamidomethyl)-pyridine at the air-water interface was studied by measuring the surface pressure-area isotherms. The amphiphile formed stable monolayers with a clear liquid-expanded (LE) to liquid-condensed phase transition at various temperatures. U

  15. Effects of perfluorinated amphiphiles on backward swimming in Paramecium caudatum

    International Nuclear Information System (INIS)

    PFOS and PFOA are ubiquitous contaminants in the environment. We investigated the effects of fluorochemicals on calcium currents in Paramecium caudatum using its behavioral changes. Negatively charged amphiphiles prolonged backward swimming (BWS) of Paramecium. PFOS significantly prolonged BWS, while PFOA was less potent (EC5: 29.8 ± 4.1 and 424.1 ± 124.0 μM, respectively). The BWS prolongation was blocked by cadmium, indicating that the cellular calcium conductance had been modified. The positively charged amphiphile FOSAPrTMA shortened BWS (EC5: 19.1 ± 17.3). Nonionic amphiphiles did not affect BWS. The longer-chain perfluorinated carboxylates PFNA and PFDA were more potent than PFOA (EC5: 98.7 ± 20.1 and 60.4 ± 10.1 μM, respectively). However, 1,8-perfluorooctanedioic acid and 1,10-perfluorodecanedioic acid did not prolong BWS. The critical micelle concentration (CMC) and BWS prolongation for negatively charged amphiphiles showed a clear correlation (r 2 = 0.8008, p < 0.001). In summary, several perfluorochemicals and PFOS and PFOA had similar effects in Paramecium, while chain length, CMC, and electric charge were major determinants of BWS duration

  16. Bio-based amphiphilic materials development and applications

    Science.gov (United States)

    Farm-based raw materials are increasingly used in the development of amphiphilic materials that have potential applications in the production of a variety of consumer and industrial products, including lubricants. Raw materials of interest include: starches, proteins, fats, oils, and sugars. These ...

  17. Amphiphiles containing aromatic groups in the hydrophobic part

    NARCIS (Netherlands)

    Visscher, Inge

    2004-01-01

    Aggregation processes are essential for life on this planet. For example, the membranes of all living cells are bilayered aggregates, consisting of lipid molecules, proteins and steroids. In many biological processes, aggregates play a role. The main driving force for aggregation of amphiphiles is h

  18. Microphase separation of diblock copolymers with amphiphilic segment

    NARCIS (Netherlands)

    Kriksin, Yury A.; Khalatur, Pavel G.; Erukhimovich, Igor Ya.; ten Brinke, Gerrit; Khokhlov, Alexei R.

    2009-01-01

    We present a statistical mechanical approach for predicting the self-assembled morphologies of amphiphilic diblock copolymers in the melt. We introduce two conformationally asymmetric linear copolymer models with a local structural asymmetry, one of a "comb-tail'' type and another that we call "cont

  19. Blends of Amphiphilic, Hyperbranched Polyesters and Different Polyolefins

    NARCIS (Netherlands)

    Schmaljohann, D.; Pötschke, P.; Hässler, R.; Voit, B.I.; Froehling, P.E.; Mostert, B.; Loontjens, J.A.

    1999-01-01

    A hyperbranched polyester based on 3,5-dihydroxybenzoic acid was completely modified with dodecanoyl chloride to result in an amphiphilic, globular polymer, which has a polar core and a nonpolar outer sphere with the ability both to incorporate an organic dye and to interact with a nonpolar matrix.

  20. Self-assembly of fibronectin mimetic peptide-amphiphile nanofibers

    Science.gov (United States)

    Rexeisen, Emilie Lynn

    Many therapeutic strategies incorporate peptides into their designs to mimic the natural protein ligands found in vivo. A few examples are the short peptide sequences RGD and PHSRN that mimic the primary and synergy-binding domains of the extracellular matrix protein, fibronectin, which is recognized by the cell surface receptor, alpha5beta 1 integrin. Even though scaffold modification with biomimetic peptides remains one of the most promising approaches for tissue engineering, the use of these peptides in therapeutic tissue-engineered products and drug delivery systems available on the commercial market is limited because the peptides are not easily able to mimic the natural protein. The design of a peptide that can effectively target the alpha5beta1 integrin would greatly increase biomimetic scaffold therapeutic potential. A novel peptide containing both the RGD primary binding domain and PHSRN synergy-binding domain for fibronectin joined with the appropriate linker should bind alpha 5beta1 integrin more efficiently and lead to greater cell adhesion over RGD alone. Several fibronectin mimetic peptides were designed and coupled to dialkyl hydrocarbon tails to make peptide-amphiphiles. The peptides contained different linkers connecting the two binding domains and different spacers separating the hydrophobic tails from the hydrophilic headgroups. The peptide-amphiphiles were deposited on mica substrates using the Langmuir-Blodgett technique. Langmuir isotherms indicated that the peptide-amphiphiles that contained higher numbers of serine residues formed a more tightly packed monolayer, but the increased number of serines also made transferring the amphiphiles to the mica substrate more difficult. Atomic force microscopy (AFM) images of the bilayers showed that the headgroups might be bent, forming small divots in the surface. These divots may help expose the PHSRN synergy-binding domain. Parallel studies undertaken by fellow group members showed that human

  1. Perfluorinated Moieties Increase the Interaction of Amphiphilic Block Copolymers with Lipid Monolayers.

    Science.gov (United States)

    Schwieger, Christian; Blaffert, Jacob; Li, Zheng; Kressler, Jörg; Blume, Alfred

    2016-08-16

    The interaction of amphiphilic and triphilic block copolymers with lipid monolayers has been studied. Amphiphilic triblock copolymer PGMA20-PPO34-PGMA20 (GP) is composed of a hydrophobic poly(propylene oxide) (PPO) middle block that is flanked by two hydrophilic poly(glycerol monomethacrylate) (PGMA) side blocks. The attachment of a perfluoro-n-nonyl residue (F9) to either end of GP yields a triphilic polymer with the sequence F9-PGMA20-PPO34-PGMA20-F9 (F-GP). The F9 chains are fluorophilic, i.e., they have a tendency to demix in hydrophilic as well as in lipophilic environments. We investigated (i) the adsorption of both polymers to differently composed lipid monolayers and (ii) the compression behavior of mixed polymer/lipid monolayers. The lipid monolayers are composed of phospholipids with PC or PE headgroups and acyl chains of different length and saturation. Both polymers interact with lipid monolayers by inserting their hydrophobic moieties (PPO, F9). The interaction is markedly enhanced in the presence of F9 chains, which act as membrane anchors. GP inserts into lipid monolayers up to a surface pressure of 30 mN/m, whereas F-GP inserts into monolayers at up to 45 mN/m, suggesting that F-GP also inserts into lipid bilayer membranes. The adsorption of both polymers to lipid monolayers with short acyl chains is favored. Upon compression, a two-step squeeze-out of F-GP occurs, with PPO blocks being released into the aqueous subphase at 28 mN/m and the F9 chains being squeezed out at 48 mN/m. GP is squeezed out in one step at 28 mN/m because of the lack of F9 anchor groups. The liquid expanded (LE) to liquid condensed (LC) phase transition of DPPC and DMPE is maintained in the presence of the polymers, indicating that the polymers can be accommodated in LE- and LC-phase monolayers. These results show how fluorinated moieties can be included in the rational design of membrane-binding polymers. PMID:27442444

  2. Chain length dependence of non-surface activity and micellization behavior of cationic amphiphilic diblock copolymers.

    Science.gov (United States)

    Ghosh, Arjun; Yusa, Shin-ichi; Matsuoka, Hideki; Saruwatari, Yoshiyuki

    2014-04-01

    The cationic and anionic amphiphilic diblock copolymers with a critical chain length and block ratio do not adsorb at the air/water interface but form micelles in solution, which is a phenomenon called "non-surface activity". This is primarily due to the high charge density of the block copolymer, which creates a strong image charge effect at the air/water interface preventing adsorption. Very stable micelle formation in bulk solution could also play an important role in the non-surface activity. To further confirm these unique properties, we studied the adsorption and micellization behavior of cationic amphiphilic diblock copolymers of poly(n-butyl acrylate)-b-poly(3-(methacryloyloxy)ethyl)trimethylammonium chloride) (PBA-b-PDMC) with different molecular weights of hydrophobic blocks but with the same ionic block length. These block copolymers were successfully prepared via consecutive reversible addition-fragmentation chain transfer (RAFT) polymerization. The block copolymer with the shortest hydrophobic block length was surface-active; the solution showed surface tension reduction and foam formation. However, above the critical block ratio, the surface tension of the solution did not decrease with increasing polymer concentration, and there was no foam formation, indicating lack of surface activity. After addition of 0.1 M NaCl, stable foam formation and slight reduction of surface tension were observed, which is reminiscent of the electrostatic nature of the non-surface activity. Fluorescence and dynamic and static light scattering measurements showed that the copolymer with the shortest hydrophobic block did not form micelles, while the block copolymers formed spherical micelles having radii of 25-30 nm. These observations indicate that micelle formation is also important for non-surface activity. Upon addition of NaCl, cmc did not decrease but rather increased as observed for non-surface-active block copolymers previously studied. The micelles formed were

  3. Photosensitizer enhanced disassembly of amphiphilic micelle for ROS-response targeted tumor therapy in vivo.

    Science.gov (United States)

    Dai, Liangliang; Yu, Yonglin; Luo, Zhong; Li, Menghuan; Chen, Weizhen; Shen, Xinkun; Chen, Feng; Sun, Qiang; Zhang, Qingfeng; Gu, Hao; Cai, Kaiyong

    2016-10-01

    This study reports a reactive oxygen species (ROS) sensitive drug delivery system based on amphiphilic polymer of poly(propylene sulfide)-polyethylene glycol-serine-folic acid (PPS-mPEG-Ser-FA). The polymer could form homogeneous micelles with an average diameter of around 80 nm through self-assembly, which would then be loaded with the singlet oxygen-generating photosensitizer of zinc phthalocyanine (ZNPC) and anti-cancer drug of DOX. The disassembly of micelles could be triggered by the hydrophobic to hydrophilic transition of the PPS core in response to ROS-induced oxidation in vitro. ZNPC molecules are capable of producing ROS under laser irradiation, which results in the rapid disassembly of micelles and releasing of the anti-tumor drug for tumor therapy under physiological condition otherwise. Moreover, the excessive ROS production deriving from ZNPC synergically induces cells apoptosis. Furthermore, the DOX loaded amphiphilic micelles could be internalized by tumor cells via FA receptor-mediated endocytosis to effectively inhibit the tumor growth in vivo, while with only minimal toxic side effects. The results in vitro and in vivo consistently demonstrate that the light-responsive micelle is a promising biodegradable nanocarrier for on-command drug release and targeted tumor therapy. PMID:27423095

  4. Strategies for encapsulation of small hydrophilic and amphiphilic drugs in PLGA microspheres: State-of-the-art and challenges.

    Science.gov (United States)

    Ramazani, Farshad; Chen, Weiluan; van Nostrum, Cornelis F; Storm, Gert; Kiessling, Fabian; Lammers, Twan; Hennink, Wim E; Kok, Robbert J

    2016-02-29

    Poly(lactide-co-glycolide) (PLGA) microspheres are efficient delivery systems for controlled release of low molecular weight drugs as well as therapeutic macromolecules. The most common microencapsulation methods are based on emulsification procedures, in which emulsified droplets of polymer and drug solidify into microspheres when the solvent is extracted from the polymeric phase. Although high encapsulation efficiencies have been reported for hydrophobic small molecules, encapsulation of hydrophilic and/or amphiphilic small molecules is challenging due to the partitioning of drug from the polymeric phase into the external phase before solidification of the particles. This review addresses formulation-related aspects for efficient encapsulation of small hydrophilic/amphiphilic molecules into PLGA microspheres using conventional emulsification methods (e.g., oil/water, water/oil/water, solid/oil/water, water/oil/oil) and highlights novel emulsification technologies such as microfluidics, membrane emulsification and other techniques including spray drying and inkjet printing. Collectively, these novel microencapsulation technologies afford production of this type of drug loaded microspheres in a robust and well controlled manner. PMID:26795193

  5. A Contact Angle Study of the Interaction between Embedded Amphiphilic Molecules and the PDMS Matrix in an Aqueous Environment

    Directory of Open Access Journals (Sweden)

    Wenjun Qiu

    2014-08-01

    Full Text Available Poly(dimethylsiloxane (PDMS surface modification via gradient-induced transport of embedded amphiphilic molecules is a novel, easy, flexible, and environmentally friendly approach for reducing protein adsorption on PDMS in microfluidic applications. To better understand the processing and the potential use in the viability-sensitive applications such as manipulation and culturing of primary neural cells, we systematically investigate how embedded molecules interact with a PDMS matrix and its surface in aqueous environments by studying the wetting angle over time under various processing conditions, including water exposure time, water exposure temperature, curing master materials, in addition to comparing different embedded amphiphilic molecules. The results indicate that the water exposure time clearly plays an important role in the surface properties. Our interpretation is that molecular rearrangement of the surface-embedded molecules improves surface coverage in the short term; while over a longer period, the transport of molecules embedded in the bulk enhance its coverage. However, this improvement finally terminates when molecules transported from the bulk to the surface are not sufficient to replace the molecules leaching into the water.

  6. ULTRAFILTRATION AS PRETREATMENT OF REVERSE OSMOSIS: LOW FOULING ULTRAFILTRATION MEMBRANE PREPARED FROM POLYETHERSULFONE–AMPHIPHILIC BLOCK COPOLYMER BLEND

    Directory of Open Access Journals (Sweden)

    Heru Susanto

    2012-02-01

    Full Text Available This paper demonstrates the preparation of polyethersulfone (PES ultrafiltration (UF membranes via wet phase inversion method using either poly(ethylene oxide-b-poly(propylene oxide-b- poly(ethylene oxide (Pluronic®, Plu or polyethylene glycol (PEG as hydrophilic modifier. Their effects on membrane structure as well as the resulting membrane performance and their stability in membrane polymer matrix were systematically investigated. The investigated membrane characteristics include surface hydrophilicity (by contact angle, surface chemistry (by FTIR spectroscopy and water flux measurement. Visualization of membrane surface and cross section morphology was also done by scanning electron microscopy. The membrane performance was examined by investigation of adsorptive fouling and ultrafiltration using solution of bovine serum albumin as the model system. The stability of additive was examined by incubating the membrane in water (40oC for up to 10 days. The results show that modification effects on membrane characteristic and low fouling behavior were clearly observed. Further, amphiphilic Pluronic generally showed better performance than PEG.   

  7. Synthesis, characterization and drug loading property of Monomethoxy-Poly(ethylene glycol)-Poly(ε-caprolactone)-Poly(D,L-lactide) (MPEG-PCLA) copolymers

    Science.gov (United States)

    Chu, BingYang; Zhang, Lan; Qu, Ying; Chen, XiaoXin; Peng, JinRong; Huang, YiXing; Qian, ZhiYong

    2016-01-01

    Amphiphilic block copolymers have attracted a great deal of attention in drug delivery systems. In this work, a series of monomethoxy-poly (ethylene glycol)-poly (ε-caprolactone-co-D,L-lactide) (MPEG-PCLA) copolymers with variable composition of poly (ε-caprolactone) (PCL) and poly (D,L-lactide) (PDLLA) were prepared via ring-opening copolymerization of ε-CL and D,L-LA in the presence of MPEG and stannous octoate. The structure and molecular weight were characterized by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The crystallinity, hydrophilicity, thermal stability and hydrolytic degradation behavior were investigated in detail, respectively. The results showed that the prepared amphiphilic MPEG-PCLA copolymers have adjustable properties by altering the composition of PCLA, which make it convenient for clinical applications. Besides, the drug loading properties were also studied. Docetaxel (DTX) could be entrapped in MPEG-PCLA micelles with high loading capacity and encapsulation efficiency. And all lyophilized DTX-loaded MPEG-PCLA micelles except MPEG-PCL micelles were readily re-dissolved in normal saline at 25 °C. In addition, DTX-loaded MPEG-PCLA micelles showed a slightly enhanced antitumor activity compared with free DTX. Furthermore, DTX micelles exhibited a slower and sustained release behavior in vitro, and higher DTX concentration and longer retention time in vivo. The results suggested that the MPEG-PCLA copolymer with the adjustable ratio of PCL to PDLLA may be a promising drug delivery carrier for DTX. PMID:27677842

  8. Aggregation of non-amphiphilic bathophenanthroline in the restricted geometry of Langmuir-Blodgett films with two different matrices

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Ajitesh [Centre of Studies in Surface Science and Technology, School of Chemistry, Sambalpur University, Jyoti Vihar-768019, Orissa (India); Panigrahi, Simanchalo [Department of Physics, National Institute of Technology, Rourkela-788011, Orissa (India); Nath, Ranendu Kumar [Department of Chemistry, Tripura University, Suryamaninagar-799130, Tripura (India); Deb, Subrata [Department of Physics, Iswar Chandra Vidyasagar College, Belonia-799155, Tripura (India); Sinha, Tripurari Prasad [Department of Physics, Bose Institute, Kolkata-700009, West Bengal (India); Mishra, Bijay Kumar, E-mail: bijaym@hotmail.com [Centre of Studies in Surface Science and Technology, School of Chemistry, Sambalpur University, Jyoti Vihar-768019, Orissa (India)

    2011-10-31

    The behavior of binary mixed Langmuir monolayers from the mixture of non-amphiphilic bathophenanthroline (BPH) and behenic acid (BA)/poly(methyl methacrylate) (PMMA) spread on aqueous subphase was investigated on the basis of the analysis of surface pressure-average area per molecule ({pi}-A) isotherms complemented with UV-vis absorption spectroscopy and scanning electron microscopy. In addition, the miscibility of the components in the two investigated mixed systems (BPH/BA and BPH/PMMA) was also tested by using additivity and surface phase rules. The plots of area per molecule versus mole fraction suggest that BPH and BA are immiscible, whereas BPH and PMMA mixtures show non-ideal behavior at low surface pressures and complete miscibility or immiscibility at higher surface pressures. Spectroscopic study reveals that J-type of aggregates is formed in the mixed films. Scanning electron microscopic study supports the presence of aggregates.

  9. Self-assembly of CdTe nanocrystals at the water/oil interface by amphiphilic hyperbranched polymers

    International Nuclear Information System (INIS)

    A general strategy for realizing the self-assembly of aqueous CdTe nanocrystals (NCs) at the water/oil interface by means of an amphiphilic core-shell hyperbranched polymer has been proposed. Aqueous CdTe NCs were firstly transferred into the chloroform phase in the presence of palmityl chloride functionalized hyperbranched poly(amidoamine) (HPAMAM-PC), and then self-assembled at the water/chloroform interface by decreasing the pH value of the aqueous phase or introducing α-CDs to the aqueous phase. The resulting CdTe/HPAMAM-PC self-assembly film was characterized by fluorescence microscopy, UV-vis, PL, TEM, EDS, FT-IR, DSC and TGA.

  10. Effect of Polyelectrolyte Stiffness and Solution pH on the Nanostructure of Complexes Formed by Cationic Amphiphiles and Negatively Charged Polyelectrolytes.

    Science.gov (United States)

    Ram-On, Maor; Cohen, Yachin; Talmon, Yeshayahu

    2016-07-01

    The interaction between amphiphiles and polyelectrolytes has been widely investigated in recent years due to their potential application in industry and medicine, with special focus on gene therapy. The cationic lipid dioleoyl trimethylammonium propane, DOTAP, and the oppositely charged polyelectrolytes, sodium poly(acrylic acid) and sodium poly(styrenesulfonate), form multilamellar complexes in water. Because of the different molecular stiffness of the two polyelectrolytes, they form different nanostructured complexes. Also, because of the different ionization behavior of the two polyelectrolytes, pH differently affects the complexation of the polyelectrolytes with didodecyldimethylammonium bromide (DDAB), another cationic surfactant. We used cryogenic temperature transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering (SAXS) to compare the nanostructures formed. Our results show that although the basic nanostructures of the complexes are always lamellar (multilamellar or unilamellar) the morphology of the complexes is affected by the polyelectrolyte rigidity and the solution pH. PMID:27049758

  11. Bioreducible unimolecular micelles based on amphiphilic multiarm hyperbranched copolymers for triggered drug release

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel type of bioreducible amphiphilic multiarm hyperbranched copolymer (H40-star-PLA-SS-PEG) based on Boltorn H40 core,poly(L-lactide) (PLA) inner-shell,and poly(ethylene glycol) (PEG) outer-shell with disulfide-linkages between the hydrophobic and hydrophilic moieties was developed as unimolecular micelles for controlled drug release triggered by reduction.The obtained H40-star-PLA-SS-PEG was characterized in detail by nuclear magnetic resonance (NMR),Fourier transform infrared (FTIR),gel permeation chromatography (GPC),differential scanning calorimeter (DSC),and thermal gravimetric analysis (TGA).Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses suggested that H40-star-PLA-SS-PEG formed stable unimolecular micelles in aqueous solution with an average diameter of 19 nm.Interestingly,these micelles aggregated into large particles rapidly in response to 10 mM dithiothreitol (DTT),most likely due to shedding of the hydrophilic PEG outer-shell through reductive cleavage of the disulfide bonds.As a hydrophobic anticancer model drug,doxorubicin (DOX) was encapsulated into these reductive unimolecular micelles.In vitro release studies revealed that under the reduction-stimulus,the detachment of PEG outer-shell in DOX-loaded micelles resulted in a rapid drug release.Flow cytometry and confocal laser scanning microscopy (CLSM) measurements indicated that these DOX-loaded micelles were easily internalized by living cells.Methyl tetrazolium (MTT) assay demonstrated a markedly enhanced drug efficacy of DOX-loaded H40-star-PLA-SS-PEG micelles as compared to free DOX.All of these results show that these bioreducible unimolecular micelles are promising carriers for the triggered intracellular delivery of hydrophobic anticancer drugs.

  12. Preparation of amphiphilic block copolymer containing triazene moieties and fluorescence study

    Indian Academy of Sciences (India)

    Emil C Buruiana; Andreea L Chibac; Violeta Melinte; Tinca Buruiana

    2013-01-01

    The present study describes the synthesis via microwave accelerated reversible additionfragmentation chain transfer (RAFT) polymerization of an amphiphilic block copolymer poly(acrylic acid)-b-poly(dodecylacrylamide-co-1-(phenyl)-3-(2-methacryloyloxyethyl carbamoyloxyethyl)-3-methyltriazene-1) [PAA-b-(PDA-co-PUMA-T)]. The structure and the chemical composition of the block copolymer were confirmed by spectral/thermal analysis. The photoreactivity of the triazene sequences from PAA-b-(PDA-co-PUMA-T) was quantified by UV/vis irradiation in chloroform/dimethylformamide solutions and in thin film, indicating that the solvent polarity modifies with an order of magnitude the rate constant values. The lower rate constant in film state (film = 1.3 × 10−3 s-1), shows that the higher mobility of polymeric chains in solution allow a more rapid orientation, favourable to the triazene bond cleavage. The capability of block copolymer to form micelles in aqueous environment and implicitly, its critical micelle concentration (CMC) was evidenced through fluorescence measurements using pyrene probe (10-6 M), the CMC value being of 4.64 × 10−3 g L-1 PAA--(PDA--PUMA-T) (3.27 × 10−7 M). Experiments of fluorescence quenching with various metal cations (UO$^{2+}_{2}$, Fe2+, Fe3+, Ni2+, Cu2+, Co2+, Pb2+ and Hg2+) suggested that such a block copolymer could find applications as fluorescence-based chemosensor for the detection of iron cations in homogeneous organic solutions or aqueous environments by thin films.

  13. Synthesis and In Vitro Evaluation of Amphiphilic Peptides and Their Nanostructured Conjugates

    Directory of Open Access Journals (Sweden)

    Samaneh Mohammadi

    2015-03-01

    Full Text Available Purpose: Breast cancer is the second leading cancer type among people of advanced countries. Various methods have been used for cancer treatment such as chemotherapy and radiotherapy. In the present study we have designed and synthesized a new group of drug delivery systems (DDS containing a new class of Cell Penetrating Peptides (CPPs named Peptide Amphiphiles (PAs. Methods: Two PAs and anionic peptides were synthesized using solid phase peptide synthesis (SPPS, namely [KW]4, [KW]5, E4 and E8. Then nano-peptides were synthesized by non-covalent binding between PAs and poly anions as [KW]4-E4, [KW]4-E8, [KW]5-E4 and [KW]5-E8. Results: Flow cytometry studies showed that increased chain length of PAs with a higher ratio between hydrophobicity and net charge results in increased intracellular uptake by MCF7 cells after 2h incubation. Moreover, nano-peptides showed greater intracellular uptake compared to PAs. Anti-proliferative assay revealed that by increasing chain length of PAs, the toxicity effect on MCF7 cells is reduced, however nano-peptides did not show significant toxicity on MCF7 cells even at high concentration levels. Conclusion: These data suggest that due to the lack of toxicity effect at high concentration levels and also high cellular uptake, nano-peptides are more suitable carrier compared to PAs for drug delivery.

  14. Determination of Concentration of Amphiphilic Polymer Molecules on the Surface of Encapsulated Semiconductor Nanocrystals.

    Science.gov (United States)

    Fedosyuk, Aleksandra; Radchanka, Aliaksandra; Antanovich, Artsiom; Prudnikau, Anatol; Kvach, Maksim V; Shmanai, Vadim; Artemyev, Mikhail

    2016-03-01

    We present a method for the determination of the average number of polymer molecules on the surface of A(II)B(VI) luminescent core-shell nanocrystals (CdSe/ZnS, ZnSe/ZnS quantum dots, and CdS/ZnS nanorods) encapsulated with amphiphilic polymer. Poly(maleic anhydride-alt-1-tetradecene) (PMAT) was quantitatively labeled with amino-derivative of fluorescein and the average amount of PMAT molecules per single nanocrystal was determined using optical absorption of the dye in the visible spectral range. The average amount of PMAT molecules grows linearly with the surface area of all studied nanocrystals. However, the surface density of the monomer units increases nonlinearly with the surface area, because of the increased competition between PMAT molecules for Zn-hexanethiol surface binding sites. The average value of zeta potential (ζ = -35 mV) was found to be independent of the size, shape, and chemical composition of nanocrystals at fixed buffer parameters (carbonate-bicarbonate buffer, pH 9.5 and 5 mM ionic strength). This finding is expected to be useful for the determination of the surface density of remaining carboxyl groups in PMAT-encapsulated nanocrystals. PMID:26866303

  15. Radiation-induced graft polymerization of amphiphilic monomers with different polymerization characteristics onto hydrophobic polysilane

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hidenori; Iwasaki, Isao; Kunai, Yuichiro [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Sato, Nobuhiro, E-mail: sato-n@rri.kyoto-u.ac.j [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Matsuyama, Tomochika [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

    2011-08-15

    The structures of poly(methyl-n-propylsilane) (PMPrS) amphiphilically modified through {gamma}-ray-induced graft polymerization were investigated with {sup 1}H NMR measurement. By the use of methyl methacrylate (MMA) or diethyl fumarate (DEF) as monomers for the graft polymerization, grafting yield rose with increasing total absorption dose and monomer concentrations, but decreased with increasing dose rate. This result means that grafting yield of modified PMPrS can be controlled by changing irradiation conditions. However, the number of PMMA or PDEF graft chains per PMPrS chain was estimated to be less than 1.0 by analysis of {sup 1}H NMR spectra, and this value was lower than that we had expected. To improve graft density, maleic anhydride (MAH), which is known as a non-homopolymerizable monomer in radical polymerization, was used as a monomer for grafting. As a result, high density grafting (one MAH unit for 4.2 silicon atoms) was attained. It demonstrates that the structure of {gamma}-ray-modified polysilane strongly depends on the polymerization characteristics of grafted monomers.

  16. Release kinetics of an amphiphilic photosensitizer by block-polymer nanoparticles.

    Science.gov (United States)

    Kerdous, Rachid; Sureau, Franck; Bour, Aurélien; Bonneau, Stéphanie

    2015-11-30

    Block-polymer nanoparticles are now well-known candidates for the delivery of various non-soluble drugs to cells. The release of drugs from these nanoparticles is a major concern related to their efficiency as nanovectors and is still not completely deciphered. Various processes have been identified, depending of both the nature of the block-polymer and those of the drugs used. We focused our interest on an amphiphilic photosensitizer studied for photodynamic treatments of cancer, Pheophorbide-a (Pheo). We studied the transfer of Pheo from poly(ethyleneglycol-b-ϵ-caprolactone) nanoparticles (I) to MCF-7 cancer cells and (II) to models of membranes. Altogether, our results suggest that the delivery of the major part of the Pheo by the nanoparticles occurs via a direct transfer of Pheo from the nanoparticles to the membrane, by collision. A minor process may involve the internalization of a small amount of the nanoplatforms by the cells. So, this research illustrates the great care necessary to address the question of the choice of such nanocarriers, in relation with the properties - in particular the relative hydrophobicity - of the drugs encapsulated, and gives elements to predict the mechanism and the efficiency of the delivery. PMID:26387620

  17. Synthesis, characterization and comparative evaluation of phenoxy ring containing long chain gemini imidazolium and pyridinium amphiphiles.

    Science.gov (United States)

    Bhadani, Avinash; Kataria, Hardeep; Singh, Sukhprit

    2011-09-01

    Two series of phenoxy ring containing long chain imidazolium and pyridinium based gemini amphiphiles have been synthesized from renewable cardanol oil having different spacers (i. e. -S-(CH(2))(n)-S-, where n is 2, 3, 4 & 6). Critical micelle concentration (cmc) of these new gemini amphiphiles has been determined by conductivity method. Further, these new cationic amphiphiles have been evaluated for their DNA binding capability by agarose gel electrophoresis, ethidium bromide exclusion experiments and transmission electron microscopy (TEM). The cytotoxicity of these new amphiphiles have been evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Comparative studies of these phenoxy ring containing long chain gemini imidazolium amphiphiles and their pyridinium analogues depicted low cmc values of the later but greater DNA interaction capability and low cytotoxicity of the former series of amphiphiles. PMID:21676409

  18. Stealth Amphiphiles: Self-Assembly of Polyhedral Boron Clusters.

    Science.gov (United States)

    Ďorďovič, Vladimír; Tošner, Zdeněk; Uchman, Mariusz; Zhigunov, Alexander; Reza, Mehedi; Ruokolainen, Janne; Pramanik, Goutam; Cígler, Petr; Kalíková, Květa; Gradzielski, Michael; Matějíček, Pavel

    2016-07-01

    This is the first experimental evidence that both self-assembly and surface activity are common features of all water-soluble boron cluster compounds. The solution behavior of anionic polyhedral boranes (sodium decaborate, sodium dodecaborate, and sodium mercaptododecaborate), carboranes (potassium 1-carba-dodecaborate), and metallacarboranes {sodium [cobalt bis(1,2-dicarbollide)]} was extensively studied, and it is evident that all the anionic boron clusters form multimolecular aggregates in water. However, the mechanism of aggregation is dependent on size and polarity. The series of studied clusters spans from a small hydrophilic decaborate-resembling hydrotrope to a bulky hydrophobic cobalt bis(dicarbollide) behaving like a classical surfactant. Despite their pristine structure resembling Platonic solids, the nature of anionic boron cluster compounds is inherently amphiphilic-they are stealth amphiphiles. PMID:27287067

  19. Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles

    Science.gov (United States)

    Qiu, Huibin; Hudson, Zachary M.; Winnik, Mitchell A.; Manners, Ian

    2015-03-01

    Self-assembly of molecular and block copolymer amphiphiles represents a well-established route to micelles with a wide variety of shapes and gel-like phases. We demonstrate an analogous process, but on a longer length scale, in which amphiphilic P-H-P and H-P-H cylindrical triblock comicelles with hydrophobic (H) or polar (P) segments that are monodisperse in length are able to self-assemble side by side or end to end in nonsolvents for the central or terminal segments, respectively. This allows the formation of cylindrical supermicelles and one-dimensional (1D) or 3D superstructures that persist in both solution and the solid state. These assemblies possess multiple levels of structural hierarchy in combination with existence on a multimicrometer-length scale, features that are generally only found in natural materials.

  20. Prebiotic Lipidic Amphiphiles and Condensing Agents on the Early Earth.

    Science.gov (United States)

    Fiore, Michele; Strazewski, Peter

    2016-01-01

    It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of vesicles that, in principle, could have compartmented first biological processes on early Earth, including the emergence of self-replicating systems. For a competitive selection of the best performing molecular replicators to become operative, some kind of bounded units capable of harboring them are indispensable. Without the competition between dynamic populations of different compartments, life itself could not be distinguished from an otherwise disparate array or network of molecular interactions. In this review, we describe experiments that demonstrate how different prebiotically-available building blocks can become precursors of phospholipids that form vesicles. We discuss the experimental conditions that resemble plausibly those of the early Earth (or elsewhere) and consider the analytical methods that were used to characterize synthetic products. Two brief sections focus on phosphorylating agents, catalysts and coupling agents with particular attention given to their geochemical context. In Section 5, we describe how condensing agents such as cyanamide and urea can promote the abiotic synthesis of phospholipids. We conclude the review by reflecting on future studies of phospholipid compartments, particularly, on evolvable chemical systems that include giant vesicles composed of different lipidic amphiphiles. PMID:27043635

  1. Prebiotic Lipidic Amphiphiles and Condensing Agents on the Early Earth

    Directory of Open Access Journals (Sweden)

    Michele Fiore

    2016-03-01

    Full Text Available It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of vesicles that, in principle, could have compartmented first biological processes on early Earth, including the emergence of self-replicating systems. For a competitive selection of the best performing molecular replicators to become operative, some kind of bounded units capable of harboring them are indispensable. Without the competition between dynamic populations of different compartments, life itself could not be distinguished from an otherwise disparate array or network of molecular interactions. In this review, we describe experiments that demonstrate how different prebiotically-available building blocks can become precursors of phospholipids that form vesicles. We discuss the experimental conditions that resemble plausibly those of the early Earth (or elsewhere and consider the analytical methods that were used to characterize synthetic products. Two brief sections focus on phosphorylating agents, catalysts and coupling agents with particular attention given to their geochemical context. In Section 5, we describe how condensing agents such as cyanamide and urea can promote the abiotic synthesis of phospholipids. We conclude the review by reflecting on future studies of phospholipid compartments, particularly, on evolvable chemical systems that include giant vesicles composed of different lipidic amphiphiles.

  2. Antifungal amphiphilic aminoglycoside K20: bioactivities and mechanism of action

    OpenAIRE

    Shrestha, Sanjib K.; Cheng-Wei T Chang; Meissner, Nicole; Oblad, John; Shrestha, Jaya P.; Sorensen, Kevin N.; Michelle M. Grilley; Jon Y Takemoto

    2014-01-01

    K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20′s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were de...

  3. Antifungal amphiphilic aminoglycoside K20: bioactivities and mechanism of action

    OpenAIRE

    Shrestha, Sanjib K.; Cheng-Wei Tom Chang; Nicole eMeissner; John eOblad; Shrestha, Jaya P.; Sorensen, Kevin N.; Michelle M. Grilley; Jon Y Takemoto

    2014-01-01

    K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20’s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were d...

  4. Relation between structure and organisation properties of new amphiphilic cyclodextrins

    International Nuclear Information System (INIS)

    Since a number of years, special attention and efforts have been made to prepare amphiphilic cyclodextrins (CDs) with the objective to use them to obtain supramolecular assemblies as such or in the presence of preformed lipidic structures. The aim of these investigation is in both cases to combine the size specificity of cyclodextrins for guests and the transport properties of phospho-lipidic structures. The final objects could be of importance to transport or target biologically relevant molecules such as drugs using new galenic formulations. In a first step, a new family of amphiphilic CDs was prepared from a pure phospholipids (DMPE) onto cyclodextrins or methylated derivatives through a spacing arm. The afforded compounds (phospholipidyl-cyclodextrins) were fully characterized by high field NMR and high resolution mass spectrometry. The methylated derivatives were shown to self-organize in water with low CMC to form fluctuating micellar fibers retaining the inclusion capacity of the cyclodextrin cavities. The interactions of these compounds with membrane systems were investigated as black films using X-ray reflectivity and by evaluation of their detergent power towards model DMPC liposomes. Their ability to cross over the Blood Brain Barrier was evidenced by a new approach making use of novel immuno-enzymatic assays. In a second step, a new class of amphiphilic cyclodextrins was considered (peptidolipidyl-cyclodextrins). Although they are structurally similar to phospholipidyl-CDs, their preparation overcomes the tedious steps of the later and lead to a considerable versatility in terms of the number of possible molecules to be prepared. Moreover, the stability problems encountered with phospholipids are avoided. Several examples have been prepared, fully characterized and their organization properties investigated by the determination of CMC and by deuterium NMR on a pure and homogeneous mixed peptidolipidyl-CD / DMPC lamellar phase. This novel class of

  5. From Vesicles to Protocells: The Roles of Amphiphilic Molecules

    OpenAIRE

    Yuka Sakuma; Masayuki Imai

    2015-01-01

    It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhes...

  6. A defect mediated lamellar to isotropic transition of amphiphile bilayers

    OpenAIRE

    Pal, Antara; Pabst, Georg; Raghunathan, V. A.

    2011-01-01

    We report the observation of a novel isotropic phase of amphiphile bilayers in a mixed system consisting of the ionic surfactant, sodium docecylsulphate (SDS), and the organic salt p-toludine hydrochloride (PTHC). This system forms a collapsed lamellar ($L_\\alpha$) phase over a wide range of water content, which transforms into an isotropic phase on heating. This transition is not observed in samples without excess water, where the $L_\\alpha$ phase is stable at higher temperatures. Our observ...

  7. The lamellar-to-isotropic transition in ternary amphiphilic systems

    OpenAIRE

    Schwarz, U. S.; Swamy, K.; Gompper, G.

    1996-01-01

    We study the dependence of the phase behavior of ternary amphiphilic systems on composition and temperature. Our analysis is based on a curvature elastic model of the surfactant film with sufficiently large spontaneous curvature and sufficiently negative saddle-splay modulus that the stable phases are the lamellar phase and a droplet microemulsion. In addition to the curvature energy, we consider the contributions to the free energy of the long-ranged van der Waals interaction and of the undu...

  8. Purely peptidic amphiphiles : understanding and controlling their self-assembled structures

    OpenAIRE

    Schuster, Thomas Bernhard

    2011-01-01

    Amphiphilic molecules spontaneously self-assemble into a variety of structures in solution. The term amphiphilic indicates that one part of the molecule is attracted to the solvent, while the other is not. Interactions such as between solute-solvent and solute-solute thus determine the organization. Understanding the self-assembly means understanding those interactions and their driving forces. In the first chapter an overview of the self-organization of amphiphilic molecules into supermolecu...

  9. Supramolecular Packing Controls H₂ Photocatalysis in Chromophore Amphiphile Hydrogels.

    Science.gov (United States)

    Weingarten, Adam S; Kazantsev, Roman V; Palmer, Liam C; Fairfield, Daniel J; Koltonow, Andrew R; Stupp, Samuel I

    2015-12-01

    Light harvesting supramolecular assemblies are potentially useful structures as components of solar-to-fuel conversion materials. The development of these functional constructs requires an understanding of optimal packing modes for chromophores. We investigated here assembly in water and the photocatalytic function of perylene monoimide chromophore amphiphiles with different alkyl linker lengths separating their hydrophobic core and the hydrophilic carboxylate headgroup. We found that these chromophore amphiphiles (CAs) self-assemble into charged nanostructures of increasing aspect ratio as the linker length is increased. The addition of salt to screen the charged nanostructures induced the formation of hydrogels and led to internal crystallization within some of the nanostructures. For linker lengths up to seven methylenes, the CAs were found to pack into 2D crystalline unit cells within ribbon-shaped nanostructures, whereas the nine methylene CAs assembled into long nanofibers without crystalline molecular packing. At the same time, the different molecular packing arrangements after charge screening led to different absorbance spectra, despite the identical electronic properties of all PMI amphiphiles. While the crystalline CAs formed electronically coupled H-aggregates, only CAs with intermediate linker lengths showed evidence of high intermolecular orbital overlap. Photocatalytic hydrogen production using a nickel-based catalyst was observed in all hydrogels, with the highest turnovers observed for CA gels having intermediate linker lengths. We conclude that the improved photocatalytic performance of the hydrogels formed by supramolecular assemblies of the intermediate linker CA molecules likely arises from improved exciton splitting efficiencies due to their higher orbital overlap. PMID:26593389

  10. Cationic amphiphiles with fatty acyl chain asymmetry of coconut oil deliver genes selectively to mouse lung.

    Science.gov (United States)

    Chandrashekhar, Voshavar; Srujan, Marepally; Prabhakar, Rairala; Reddy, Rakesh C; Sreedhar, Bojja; Rentam, Kiran K R; Kanjilal, Sanjit; Chaudhuri, Arabinda

    2011-03-16

    Recent structure-activity studies have revealed a dramatic influence of hydrophobic chain asymmetry in enhancing gene delivery efficacies of synthetic cationic amphiphiles (Nantz, M. H. et al. Mol. Pharmaceutics2010, 7, 786-794; Koynova, R. et al. Mol. Pharmaceutics2009, 6, 951-958). The present findings demonstrate for the first time that such a transfection enhancing influence of asymmetric hydrocarbon chains observed in pure synthetic cationic amphiphiles also works for cationic amphiphiles designed with natural, asymmetric fatty acyl chains of a food-grade oil. Herein, we demonstrate that cationic amphiphiles designed with the natural fatty acyl chain asymmetry of food-grade coconut oil are less cytotoxic and deliver genes selectively to mouse lung. Despite lauroyl chains being the major fatty acyl chains of coconut oil, both the in vitro and In vivo gene transfer efficiencies of such cationic amphiphiles were found to be remarkably superior (>4-fold) to those of their pure dilauroyl analogue. Mechanistic studies involving the technique of fluorescence resonance energy transfer (FRET) revealed higher biomembrane fusibility of the cationic liposomes of the coconut amphiphiles than that of the symmetric dilauroyl analogue. AFM study revealed pronounced fusogenic nonlamellar structures of the liposomes of coconut amphiphiles. Findings in the FRET and cellular uptake study, taken together, support the notion that the higher cellular uptake resulting from the more fusogenic nature of the liposomes of coconut amphiphiles 1 are likely to play a dominant role in making the coconut amphiphiles transfection competent.

  11. Self-assembly of amphiphilic molecules:A review on the recent computer simulation results

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We provided a short review on the recent progresses in computer simulations of adsorption and self-assembly of amphiphilic molecules.Owing to the extensive applications of amphiphilic molecules,it is very important to understand thoroughly the effects of the detailed chemistry,solid surfaces and the degree of confinement on the aggregate morphologies and kinetics of self-assembly for amphiphilic systems.In this review we paid special attention on(i) morphologies of adsorbed surfactants on solid surfaces,(ii) self-assembly in confined systems,and(iii) kinetic processes involving amphiphilic molecules.

  12. Amphiphiles Self-Assembly: Basic Concepts and Future Perspectives of Supramolecular Approaches

    Directory of Open Access Journals (Sweden)

    Domenico Lombardo

    2015-01-01

    Full Text Available Amphiphiles are synthetic or natural molecules with the ability to self-assemble into a wide variety of structures including micelles, vesicles, nanotubes, nanofibers, and lamellae. Self-assembly processes of amphiphiles have been widely used to mimic biological systems, such as assembly of lipids and proteins, while their integrated actions allow the performance of highly specific cellular functions which has paved a way for bottom-up bionanotechnology. While amphiphiles self-assembly has attracted considerable attention for decades due to their extensive applications in material science, drug and gene delivery, recent developments in nanoscience stimulated the combination of the simple approaches of amphiphile assembly with the advanced concept of supramolecular self-assembly for the development of more complex, hierarchical nanostructures. Introduction of stimulus responsive supramolecular amphiphile assembly-disassembly processes provides particularly novel approaches for impacting bionanotechnology applications. Leading examples of these novel self-assembly processes can be found, in fact, in biosystems where assemblies of different amphiphilic macrocomponents and their integrated actions allow the performance of highly specific biological functions. In this perspective, we summarize in this tutorial review the basic concept and recent research on self-assembly of traditional amphiphilic molecules (such as surfactants, amphiphile-like polymers, or lipids and more recent concepts of supramolecular amphiphiles assembly which have become increasingly important in emerging nanotechnology.

  13. 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

    Science.gov (United States)

    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

  14. Heparin-binding peptide amphiphile supramolecular architectures as platforms for angiogenesis and drug delivery

    Science.gov (United States)

    Chow, Lesleyann W.

    A fascinating phenomenon in nature is the self-assembly of molecules into a functional, hierarchical structure. In the past decade, the Stupp Laboratory has developed several classes of self-assembling biomaterials, one of which is the synthetic peptide amphiphile (PA). Self-assembling PAs are attractive and versatile biomolecules that can be customized for specific applications in regenerative medicine. In particular, a heparin-binding peptide amphiphile (HBPA) containing a specific heparin-binding peptide sequence was used here to induce angiogenesis and serve as a delivery vehicle for growth factors and small hydrophobic molecules. Throughout this dissertation, the HBPA/heparin system is used in different architectures for a variety of regenerative medicine applications. In one aspect of this work, hybrid scaffolds made from HBPA/heparin gelled on a poly(L-lactic acid) (PLLA) fiber mesh were used to promote angiogenesis to facilitate pancreatic islet transplantation for the treatment of type 1 diabetes. Delivery of growth factors with HBPA/PLLA scafflolds increased vessel density in vivo and correlated with improved transplant outcomes in a streptozotocin-induced diabetic mouse model. Soluble HBPA nanofiber architectures were also useful for islet transplantation applications. These nanofibers were used at concentrations below gelation to deliver growth factors into the dense islet cell aggregate, promoting cell survival and angiogenesis in vitro. The nanostructures infiltrated the islets and promoted the retention of heparin and growth factors within the islet. Another interesting growth factor release system discussed here is the HBPA membrane structure. HBPA was found to self-assemble with hyaluronic acid, a large biopolymer found in the body, into macroscopic, hierarchically-ordered membranes. Heparin was incorporated into these membranes and affected the membrane's mechanical properties and growth factor release. Human mesenchymal stem cells were also shown

  15. Hole polarons in poly(G)-poly(C) and poly(A)-poly(T) DNA molecules

    Institute of Scientific and Technical Information of China (English)

    CUI Peng; WU Jian; ZHANG GuiQing; LIU ChengBu

    2008-01-01

    The polaron might play an important role in the process of charge migration through duplex DNA stack. In the present work, we investigate properties of hole polarons in DNA molecules containing identical base pairs, such as poly(G)-poly(C) and poly(A)-poly(T), An extended Ught-binding model (extended Su-Schrieffer-Heeger model), which involves the effect of an electric field in the direction of DNA stack, will be introduced. The transfer integral and electron-phonon coupling parameters in this model are obtained according to ab initio calculation for different base pair dimers. Calculations reveal that the polaron in poly(A)-poly(T) has a wider shape and a higher mobility under a specific electric field than that in poly(G)-poly(C) DNA stack.

  16. Hole polarons in poly(G)-poly(C) and poly(A)-poly(T) DNA molecules

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The polaron might play an important role in the process of charge migration through duplex DNA stack. In the present work, we investigate properties of hole polarons in DNA molecules containing identical base pairs, such as poly(G)-poly(C) and poly(A)-poly(T), An extended tight-binding model (extended Su-Schrieffer-Heeger model), which involves the effect of an electric field in the direction of DNA stack, will be introduced. The transfer integral and electron-phonon coupling parameters in this model are obtained according to ab initio calculation for different base pair dimers. Calculations reveal that the polaron in poly(A)-poly(T) has a wider shape and a higher mobility under a specific electric field than that in poly(G)-poly(C) DNA stack.

  17. Dehydration-induced redistribution of amphiphilic molecules between cytoplasm and lipids is associated with desiccation tolerance in seeds

    NARCIS (Netherlands)

    Buitink, J.; Leprince, O.; Hoekstra, F.A.

    2000-01-01

    This study establishes a relationship between desiccation tolerance and the transfer of amphiphilic molecules from the cytoplasm into lipids during drying, using electron paramagnetic resonance spectroscopy of amphiphilic spin probes introduced into imbibed radicles of pea (Pisum sativum) and cucumb

  18. In vitro controlled release of clove essential oil in self-assembly of amphiphilic polyethylene glycol-block-polycaprolactone.

    Science.gov (United States)

    Thonggoom, O; Punrattanasin, N; Srisawang, N; Promawan, N; Thonggoom, R

    2016-05-01

    In this study, a micellar delivery system with an amphiphilic diblock copolymer of poly (ethylene glycol) and poly (ɛ-caprolactone) was synthesised and used to incorporate hydrophobic clove essential oil (CEO). To determine an optimal delivery system, the effects of the copolymer's hydrophobic block length and the CEO-loading content on the encapsulation of CEO were investigated. Percentages of entrapment efficiency (%EE), CEO loading (%CEO), and in vitro release profiles were determined. The size, size distribution, zeta potential, and morphology of the obtained micelles were determined by DLS, FE-SEM, and TEM. The %EE, %CEO, and in vitro release profiles of CEO incorporated in micelles were analysed by HPLC. The study revealed a sustained release profile of CEO from CEO-loaded micelles. The results indicate the successful formulation of CEO-loaded PEG-b-PCL micelle nanoparticles. It is suggested that this micelle system has considerably potential applications in the sustained release of CEO in intravascular drug delivery. PMID:26988617

  19. Visual tracing of diffusion and biodistribution for amphiphilic cationic nanoparticles using photoacoustic imaging after ex vivo intravitreal injections

    Science.gov (United States)

    Xu, Xu; Xu, Zhaokang; Liu, Junyi; Zhang, Zhaoliang; Chen, Hao; Li, Xingyi; Shi, Shuai

    2016-01-01

    To visually trace the diffusion and biodistribution of amphiphilic cation micelles after vitreous injection, various triblock copolymers of monomethoxy poly(ethylene glycol)–poly(ε-caprolactone)–polyethylenimine were synthesized with different structures of hydrophilic and hydrophobic segments, followed by labeling with near-infrared fluorescent dye Cyanine5 or Cyanine7. The micellar size, polydispersity index, and surface charge were measured by dynamic light scattering. The diffusion was monitored using photoacoustic imaging in real time after intravitreal injections. Moreover, the labeled nanoparticle distribution in the posterior segment of the eye was imaged histologically by confocal microscopy. The results showed that the hydrophilic segment increased vitreous diffusion, while a positive charge on the particle surface hindered diffusion. In addition, the particles diffused through the retinal layers and were enriched in the retinal pigment epithelial layer. This work tried to study the diffusion rate via a simple method by using visible images, and then provided basic data for the development of intraocular drug carriers. PMID:27785015

  20. Visual tracing of diffusion and biodistribution for amphiphilic cationic nanoparticles using photoacoustic imaging after ex vivo intravitreal injections

    Directory of Open Access Journals (Sweden)

    Xu X

    2016-10-01

    Full Text Available Xu Xu,* Zhaokang Xu,* Junyi Liu, Zhaoliang Zhang, Hao Chen, Xingyi Li, Shuai Shi Institute of Biomedical Engineering, School of Ophthalmology & Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People’s Republic of China *These authors contributed equally to this work Abstract: To visually trace the diffusion and biodistribution of amphiphilic cation micelles after vitreous injection, various triblock copolymers of monomethoxy poly(ethylene glycol–poly(ε-caprolactone–polyethylenimine were synthesized with different structures of hydrophilic and hydrophobic segments, followed by labeling with near-infrared fluorescent dye Cyanine5 or Cyanine7. The micellar size, polydispersity index, and surface charge were measured by dynamic light scattering. The diffusion was monitored using photoacoustic imaging in real time after intravitreal injections. Moreover, the labeled nanoparticle distribution in the posterior segment of the eye was imaged histologically by confocal microscopy. The results showed that the hydrophilic segment increased vitreous diffusion, while a positive charge on the particle surface hindered diffusion. In addition, the particles diffused through the retinal layers and were enriched in the retinal pigment epithelial layer. This work tried to study the diffusion rate via a simple method by using visible images, and then provided basic data for the development of intraocular drug carriers. Keywords: visible tracing, cavum vitreum, biodistribution, diffusion rate

  1. Composition and method for self-assembly and mineralization of peptide-amphiphiles

    Science.gov (United States)

    Stupp, Samuel I.; Beniash, Elia; Hartgerink, Jeffrey D.

    2012-02-28

    The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.

  2. Composition and method for self-assembly and mineralization of peptide amphiphiles

    Science.gov (United States)

    Stupp, Samuel I.; Beniash, Elia; Hartgerink, Jeffrey D.

    2009-06-30

    The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.

  3. Stable Vesicles Composed of Mono- or Dicarboxylic Fatty Acids and Trimethylammonium Amphiphiles

    DEFF Research Database (Denmark)

    Caschera, Filippo; Bernardino de la Serna, Jorge; Löffler, Philipp M. G.;

    2011-01-01

    The self-assembly of cationic and anionic amphiphile mixtures into vesicles in aqueous media was studied using two different systems: i) decanoic acid and trimethyldecylammonium bromide ii) hexadecanedioic acid (a simple bola-amphiphile) and trimethyldecylammonium bromide. The resulting vesicles ...

  4. Phosphate bioisostere containing amphiphiles: a novel class of squaramide-based lipids.

    Science.gov (United States)

    Saha, Abhishek; Panda, Subhankar; Paul, Saurav; Manna, Debasis

    2016-07-19

    We describe a novel class of amphiphiles with squaramide moiety as a phosphate bioisostere. Most synthesized squaramide-based amphiphiles have the favorable physicochemical properties of lipids, such as: formation of stable liposomes or giant unilamellar vesicles in aqueous solution, high phase-transition temperature, low vesicle leakage and phospholipase resistance properties. PMID:27377058

  5. From Vesicles to Protocells: The Roles of Amphiphilic Molecules

    Directory of Open Access Journals (Sweden)

    Yuka Sakuma

    2015-03-01

    Full Text Available It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures and the phase separation. This achievement will elucidate the pathway from molecular assembly to cellular life.

  6. From vesicles to protocells: the roles of amphiphilic molecules.

    Science.gov (United States)

    Sakuma, Yuka; Imai, Masayuki

    2015-01-01

    It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures) and the phase separation. This achievement will elucidate the pathway from molecular assembly to cellular life. PMID:25738256

  7. Identification of new members within suites of amphiphilic marine siderophores

    OpenAIRE

    Vraspir, Julia M.; Holt, Pamela D.; Butler, Alison

    2010-01-01

    Marine bacterial isolates Vibrio sp. HC0601C5 and Halomonas meridiana str. HC4321C1 were isolated off the coast of southern California and were found to produce an expanded suite of previously identified amphiphilic siderophores. Specifically two new members of the amphibactin family, amphibactins S and T, which have a C14:1 ω-7 fatty acid and a saturated C12 fatty acid, respectively, were produced by Vibrio sp. HC0601C5. These siderophores are produced in addition to a number of previously d...

  8. Amphiphilic core-shell nanoparticles containing dense polyethyleneimine shells for efficient delivery of microRNA to Kupffer cells.

    Science.gov (United States)

    Liu, Zuojin; Niu, Dechao; Zhang, Junyong; Zhang, Wenfeng; Yao, Yuan; Li, Pei; Gong, Jianping

    2016-01-01

    Efficient and targeted delivery approach to transfer exogenous genes into macrophages is still a great challenge. Current gene delivery methods often result in low cellular uptake efficiency in vivo in some types of cells, especially for the Kupffer cells (KCs). In this article, we demonstrate that amphiphilic core-shell nanoparticles (NPs) consisting of well-defined hydrophobic poly(methyl methacrylate) (PMMA) cores and branched polyethyleneimine (PEI) shells (denoted as PEI@PMMA NPs) are efficient nanocarriers to deliver microRNA (miRNA)-loaded plasmid to the KCs. Average hydrodynamic diameter of PEI@ PMMA NPs was 279 nm with a narrow size distribution. The NPs also possessed positive surface charges up to +30 mV in water, thus enabling effective condensation of negatively charged plasmid DNA. Gel electrophoresis assay showed that the resultant PEI@PMMA NPs were able to completely condense miRNA plasmid at a weight ratio of 25:1 (N/P ratio equal to 45:1). The Cell Counting Kit-8 assay and flow cytometry results showed that the PEI@PMMA/miRNA NPs displayed low cytotoxicity and cell apoptosis activity against the KCs. The maximum cell transfection efficiency reached 34.7% after 48 hours, which is much higher than that obtained by using the commercial Lipofectamine™ 2000 (1.7%). Bio-transmission electron microscope observation revealed that the PEI@PMMA NPs were mainly distributed in the cytoplasm of the KCs. Furthermore, when compared to the control groups, the protein expression of target nuclear factor κB P65 was considerably inhibited (P<0.05) both in vitro and in vivo. These results demonstrate that the PEI@PMMA NPs with a unique amphiphilic core-shell nanostructure are promising nanocarriers for delivering miRNA plasmid to KCs.

  9. Amphiphilic core–shell nanoparticles containing dense polyethyleneimine shells for efficient delivery of microRNA to Kupffer cells

    Science.gov (United States)

    Liu, Zuojin; Niu, Dechao; Zhang, Junyong; Zhang, Wenfeng; Yao, Yuan; Li, Pei; Gong, Jianping

    2016-01-01

    Efficient and targeted delivery approach to transfer exogenous genes into macrophages is still a great challenge. Current gene delivery methods often result in low cellular uptake efficiency in vivo in some types of cells, especially for the Kupffer cells (KCs). In this article, we demonstrate that amphiphilic core–shell nanoparticles (NPs) consisting of well-defined hydrophobic poly(methyl methacrylate) (PMMA) cores and branched polyethyleneimine (PEI) shells (denoted as PEI@PMMA NPs) are efficient nanocarriers to deliver microRNA (miRNA)-loaded plasmid to the KCs. Average hydrodynamic diameter of PEI@ PMMA NPs was 279 nm with a narrow size distribution. The NPs also possessed positive surface charges up to +30 mV in water, thus enabling effective condensation of negatively charged plasmid DNA. Gel electrophoresis assay showed that the resultant PEI@PMMA NPs were able to completely condense miRNA plasmid at a weight ratio of 25:1 (N/P ratio equal to 45:1). The Cell Counting Kit-8 assay and flow cytometry results showed that the PEI@PMMA/miRNA NPs displayed low cytotoxicity and cell apoptosis activity against the KCs. The maximum cell transfection efficiency reached 34.7% after 48 hours, which is much higher than that obtained by using the commercial Lipofectamine™ 2000 (1.7%). Bio-transmission electron microscope observation revealed that the PEI@PMMA NPs were mainly distributed in the cytoplasm of the KCs. Furthermore, when compared to the control groups, the protein expression of target nuclear factor κB P65 was considerably inhibited (P<0.05) both in vitro and in vivo. These results demonstrate that the PEI@PMMA NPs with a unique amphiphilic core–shell nanostructure are promising nanocarriers for delivering miRNA plasmid to KCs. PMID:27366061

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

    Science.gov (United States)

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

    2012-12-11

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

  11. Amphiphilic core shell nanoparticles containing dense polyethyleneimine shells for efficient delivery of microRNA to Kupffer cells

    Directory of Open Access Journals (Sweden)

    Liu Z

    2016-06-01

    Full Text Available Zuojin Liu,1,* Dechao Niu,2,3,* Junyong Zhang,1 Wenfeng Zhang,1 Yuan Yao,2 Pei Li,2 Jianping Gong1 1Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 2Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, 3Lab of Low-Dimensional Materials Chemistry, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: Efficient and targeted delivery approach to transfer exogenous genes into macrophages is still a great challenge. Current gene delivery methods often result in low cellular uptake efficiency in vivo in some types of cells, especially for the Kupffer cells (KCs. In this article, we demonstrate that amphiphilic core–shell nanoparticles (NPs consisting of well-defined hydrophobic poly(methyl methacrylate (PMMA cores and branched polyethyleneimine (PEI shells (denoted as PEI@PMMA NPs are efficient nanocarriers to deliver microRNA (miRNA-loaded plasmid to the KCs. Average hydrodynamic diameter of PEI@PMMA NPs was 279 nm with a narrow size distribution. The NPs also possessed positive surface charges up to +30 mV in water, thus enabling effective condensation of negatively charged plasmid DNA. Gel electrophoresis assay showed that the resultant PEI@PMMA NPs were able to completely condense miRNA plasmid at a weight ratio of 25:1 (N/P ratio equal to 45:1. The Cell Counting Kit-8 assay and flow cytometry results showed that the PEI@PMMA/miRNA NPs displayed low cytotoxicity and cell apoptosis activity against the KCs. The maximum cell transfection efficiency reached 34.7% after 48 hours, which is much higher than that obtained by using the commercial Lipofectamine™ 2000 (1.7%. Bio-transmission electron microscope observation revealed that the PEI@PMMA NPs were mainly distributed in

  12. Amphiphilic copolymers based on polyoxazoline and grape seed vegetable oil derivatives: self-assemblies and dynamic light scattering

    International Nuclear Information System (INIS)

    The self-assembly in solution of original structures of amphiphilic partially natural copolymers based on polyoxazoline [more precisely poly(2-methyl-2-oxazoline) (POx)] and grape seed vegetable oil derivatives (linear, T-, and trident-structure) is investigated. The results show that such systems are found, using dynamic light scattering (DLS), to spontaneously self-organize into monomodal, narrow-size, and stable nanoparticles in aqueous medium. The obtained hydrodynamic diameters (Dh) range from 8.6 to 32.5 nm. Specifically, such size increases strongly with increasing natural block (i.e., lipophilic species) length due to higher hydrophobic interactions (from 10.1 nm for C19 to 19.2 nm for C57). Furthermore, increasing the polyoxazoline (i.e., hydrophilic block) length leads to a moderate linear increase of the Dh-values. Therefore, the first-order size effect comes from the natural lipophilic block, whereas the characteristic size can be tuned more finely (i.e., in a second-order) by choosing appropriately the polyoxazoline length. The DLS results in terms of characteristic size are corroborated using nanoparticle tracking analysis (NTA), and also by atomic force microscopy (AFM) and transmission electron microscopy (TEM) imaging where well-defined spherical and individual nanoparticles exhibit a very good mechanical resistance upon drying. Moreover, changing the lipophilic block architecture from linear to T-shape, while keeping the same molar mass, generates a branching and thus a shrinking by a factor of 2 of the nanoparticle volume, as observed by DLS. In this paper, it is clearly shown that the self-assemblies of amphiphilic block copolymer obtained from grape seed vegetable oil derivatives (sustainable renewable resources) as well as their tunability are of great interest for biomass valorization at the nanoscale level [continuation of the article by Stemmelen et al. (Polym Chem 4:1445–1458, 2013)].Graphical AbstractAmphiphilic copolymers based on

  13. Amphiphilic copolymers based on polyoxazoline and grape seed vegetable oil derivatives: self-assemblies and dynamic light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Travelet, Christophe, E-mail: Christophe.Travelet@cermav.cnrs.fr [Universite Joseph Fourier (UJF), Institut de Chimie Moleculaire de Grenoble (ICMG-FR 2607 CNRS), PolyNat Carnot institute, Arcane LabEx, domaine universitaire de Grenoble, Centre de Recherches sur les Macromolecules Vegetales - CERMAV-UPR 5301 CNRS (France); Stemmelen, Mylene; Lapinte, Vincent [Universite de Montpellier II, Institut Charles Gerhardt Montpellier (UMR 5253 CNRS-UM2-UM1-ENSCM), equipe ingenierie et architectures macromoleculaires (France); Dubreuil, Frederic [Universite Joseph Fourier (UJF), Institut de Chimie Moleculaire de Grenoble (ICMG-FR 2607 CNRS), PolyNat Carnot institute, Arcane LabEx, domaine universitaire de Grenoble, Centre de Recherches sur les Macromolecules Vegetales - CERMAV-UPR 5301 CNRS (France); Robin, Jean-Jacques [Universite de Montpellier II, Institut Charles Gerhardt Montpellier (UMR 5253 CNRS-UM2-UM1-ENSCM), equipe ingenierie et architectures macromoleculaires (France); and others

    2013-06-15

    The self-assembly in solution of original structures of amphiphilic partially natural copolymers based on polyoxazoline [more precisely poly(2-methyl-2-oxazoline) (POx)] and grape seed vegetable oil derivatives (linear, T-, and trident-structure) is investigated. The results show that such systems are found, using dynamic light scattering (DLS), to spontaneously self-organize into monomodal, narrow-size, and stable nanoparticles in aqueous medium. The obtained hydrodynamic diameters (D{sub h}) range from 8.6 to 32.5 nm. Specifically, such size increases strongly with increasing natural block (i.e., lipophilic species) length due to higher hydrophobic interactions (from 10.1 nm for C{sub 19} to 19.2 nm for C{sub 57}). Furthermore, increasing the polyoxazoline (i.e., hydrophilic block) length leads to a moderate linear increase of the D{sub h}-values. Therefore, the first-order size effect comes from the natural lipophilic block, whereas the characteristic size can be tuned more finely (i.e., in a second-order) by choosing appropriately the polyoxazoline length. The DLS results in terms of characteristic size are corroborated using nanoparticle tracking analysis (NTA), and also by atomic force microscopy (AFM) and transmission electron microscopy (TEM) imaging where well-defined spherical and individual nanoparticles exhibit a very good mechanical resistance upon drying. Moreover, changing the lipophilic block architecture from linear to T-shape, while keeping the same molar mass, generates a branching and thus a shrinking by a factor of 2 of the nanoparticle volume, as observed by DLS. In this paper, it is clearly shown that the self-assemblies of amphiphilic block copolymer obtained from grape seed vegetable oil derivatives (sustainable renewable resources) as well as their tunability are of great interest for biomass valorization at the nanoscale level [continuation of the article by Stemmelen et al. (Polym Chem 4:1445-1458, 2013)].Graphical AbstractAmphiphilic

  14. Synthesis and evaluation of amphiphilic peptides as nanostructures and drug delivery tools

    Science.gov (United States)

    Sayeh, Naser Ali

    Intracellular delivery of cell-impermeable compounds in a variety cells using delivery systems have been extensively studied in recent years. Obtaining desirable cellular uptake levels often requires the administration of high quantities of drugs to achieve the expected intracellular biological effect. Thus, improving the translocation process across the plasma membrane will significantly reduce the quantity of required administered drug and consequently minimize the side effects in most of the cases. Efficient delivery of these molecules to the cells and tissues is a difficult challenge. Compounds with low cellular permeability are commonly considered to be of limited therapeutic value. Over the past few decades, several biomedical carriers, such as polymers, nanospheres, nanocapsules, liposomes, micelles, peptides and dendrimers have been widely used to deliver therapeutic and diagnostic agents to the cells. Biomaterials generated from nano-scale compounds have shown some promising data for delivery of many compounds in a number of diseases, such as viral infections, cancer, and genetic disorders. Although much progress has been achieved in this field, many challenges still remain, such as toxicity and limited stability. Liposomes suffer from poor stability in the bloodstream and leakage during storage. They tend to aggregate and fuse with or leak entrapped drugs, especially highly hydrophilic small molecules. For solid lipid nanoparticles (SLNs), drug expulsion after polymorphic transition during storage, inadequate loading capacity, and relatively high water content of the dispersions have been observed. Poly(lactic-coglycolic acid (PLGA) degrades in the body producing its original monomers of lactic acid and glycolic acid, which are the by-products of various metabolic pathways. However, this acidic microenvironment that occurs during degradation could negatively affect the stability of the loaded compound. Dendrimers can carry drugs as complexes or as

  15. Amphiphilic block-graft copolymer templates for organized mesoporous TiO2 films in dye-sensitized solar cells

    Science.gov (United States)

    Lim, Jung Yup; Lee, Chang Soo; Lee, Jung Min; Ahn, Joonmo; Cho, Hyung Hee; Kim, Jong Hak

    2016-01-01

    Amphiphilic block-graft copolymers composed of poly(styrene-b-butadiene-b-styrene) (SBS) backbone and poly(oxyethylene methacrylate) (POEM) side chains are synthesized and combined with hydrophilically preformed TiO2 (Pre-TiO2), which works as a structural binder as well as titania source. This results in the formation of crack free, 6-μm-thick, organized mesoporous TiO2 (OM-TiO2) films via one-step doctor-blading based on self-assembly of SBS-g-POEM as well as preferential interaction of POEM chains with Pre-TiO2. SBS-g-POEM with different numbers of ethylene oxide repeating units, SBS-g-POEM(500) and SBS-g-POEM(950), are used to form OM-TiO2(500) and OM-TiO2(950), respectively. The efficiencies of dye-sensitized solar cells (DSSCs) with a quasi-solid-state polymer electrolyte reach 5.7% and 5.8% at 100 mW/cm2 for OM-TiO2(500) and OM-TiO2(950), respectively. The surface area of OM-TiO2(950) was greater than that of OM-TiO2(500) but the light reflectance was lower in the former, which is responsible for similar efficiency. Both DSSCs exhibit much higher efficiency than one (4.8%) with randomly-organized particulate TiO2 (Ran-TiO2), which is attributed to the higher dye loading, reduced charge recombination and improved pore infiltration of OM-TiO2. When utilizing poly((1-(4-ethenylphenyl)methyl)-3-butyl-imidazolium iodide) (PEBII) and mesoporous TiO2 spheres as the solid electrolyte and the scattering layer, the efficiency increases up to 7.5%, one of the highest values for N719-based solid-state DSSCs.

  16. Formation of nanoscale networks: selectively swelling amphiphilic block copolymers with CO2-expanded liquids

    Science.gov (United States)

    Gong, Jianliang; Zhang, Aijuan; Bai, Hua; Zhang, Qingkun; Du, Can; Li, Lei; Hong, Yanzhen; Li, Jun

    2013-01-01

    Polymeric films with nanoscale networks were prepared by selectively swelling an amphiphilic diblock copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), with the CO2-expanded liquid (CXL), CO2-methanol. The phase behavior of the CO2-methanol system was investigated by both theoretical calculation and experiments, revealing that methanol can be expanded by CO2, forming homogeneous CXL under the experimental conditions. When treated with the CO2-methanol system, the spin cast compact PS-b-P4VP film was transformed into a network with interconnected pores, in a pressure range of 12-20 MPa and a temperature range of 45-60 °C. The formation mechanism of the network, involving plasticization of PS and selective swelling of P4VP, was proposed. Because the diblock copolymer diffusion process is controlled by the activated hopping of individual block copolymer chains with the thermodynamic barrier for moving PVP segments from one to another, the formation of the network structures is achieved in a short time scale and shows ``thermodynamically restricted'' character. Furthermore, the resulting polymer networks were employed as templates, for the preparation of polypyrrole networks, by an electrochemical polymerization process. The prepared porous polypyrrole film was used to fabricate a chemoresistor-type gas sensor which showed high sensitivity towards ammonia.Polymeric films with nanoscale networks were prepared by selectively swelling an amphiphilic diblock copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), with the CO2-expanded liquid (CXL), CO2-methanol. The phase behavior of the CO2-methanol system was investigated by both theoretical calculation and experiments, revealing that methanol can be expanded by CO2, forming homogeneous CXL under the experimental conditions. When treated with the CO2-methanol system, the spin cast compact PS-b-P4VP film was transformed into a network with interconnected pores, in a pressure range of 12-20 MPa and a

  17. Poly(Lactic Acid) Hemodialysis Membranes with Poly(Lactic Acid)-block-Poly(2-Hydroxyethyl Methacrylate) Copolymer As Additive: Preparation, Characterization, and Performance.

    Science.gov (United States)

    Zhu, Lijing; Liu, Fu; Yu, Xuemin; Xue, Lixin

    2015-08-19

    Poly(lactic acid) (PLA) hemodialysis membranes with enhanced antifouling capability and hemocompatibility were developed using poly(lactic acid)-block-poly(2-hydroxyethyl methacrylate) (PLA-PHEMA) copolymers as the blending additive. PLA-PHEMA block copolymers were synthesized via reversible addition-fragmentation (RAFT) polymerization from aminolyzed PLA. Gel permeation chromatography (GPC) and (1)H-nuclear magnetic resonance ((1)H NMR) were applied to characterize the synthesized products. By blending PLA with the amphiphilic block copolymer, PLA/PLA-PHEMA membranes were prepared by nonsolvent induced phase separation (NIPS) method. Their chemistry and structure were characterized with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM). The results revealed that PLA/PLA-PHEMA membranes with high PLA-PHEMA contents exhibited enhanced hydrophilicity, water permeability, antifouling and hemocompatibility. Especially, when the PLA-PHEMA concentration was 15 wt %, the water flux of the modified membrane was about 236 L m(-2) h(-1). Its urea and creatinine clearance was more than 0.70 mL/min, lysozyme clearance was about 0.50 mL/min, BSA clearance was as less as 0.31 mL/min. All the results suggest that PLA-PHEMA copolymers had served as effective agents for optimizing the property of PLA-based membrane for hemodialysis applications. PMID:26222398

  18. Amphiphilic biopolymers (amphibiopols) as new surfactants for membrane protein solubilization

    Science.gov (United States)

    Duval-Terrié, Caroline; Cosette, Pascal; Molle, Gérard; Muller, Guy; Dé, Emmanuelle

    2003-01-01

    The aim of this study was to develop new surfactants for membrane protein solubilization, from a natural, biodegradable polymer: the polysaccharide pullulan. A set of amphiphilic pullulans (HMCMPs), differing in hydrophobic modification ratio, charge ratio, and the nature of the hydrophobic chains introduced, were synthesized and tested in solubilization experiments with outer membranes of Pseudomonas fluorescens. The membrane proteins were precipitated, and then resolubilized with various HMCMPs. The decyl alkyl chain (C10) was the hydrophobic graft that gave the highest level of solubilization. Decyl alkyl chain-bearing HMCMPs were also able to extract integral membrane proteins from their lipid environment. The best results were obtained with an amphiphilic pullulan bearing 18% decyl groups (18C10). Circular dichroism spectroscopy and membrane reconstitution experiments were used to test the structural and functional integrity of 18C10-solubilized proteins (OmpF from Escherichia coli and bacteriorhodopsin from Halobacterium halobium). Whatever their structure type (α or β), 18C10 did not alter either the structure or the function of the proteins analyzed. Thus, HMCMPs appear to constitute a promising new class of polymeric surfactants for membrane protein studies. PMID:12649425

  19. Preparation and Properties of Vesicles from Condensable Amphiphilic Amino Acids

    Institute of Scientific and Technical Information of China (English)

    熊向源; 何巍; 李子臣; 李福绵

    2001-01-01

    Three double-chain amphiphiles with amino acid groups as hydrphilic moiety were synthesized. These amphiphiles can be easily dispersed in buffer solution to form transparent dispersion. Examination of the dispersion by transmission electron microscopy (TEM) showed the formation of stable vesicular aggregates, which was also confirmed by the ability to encapsulate water-soluble dyes. Since amino acid groups are located on the surface of the vesicles, water-soluble carbodiimide can induce the condensation of these groups to form peptide. The phase transition temperatures of these vesicles were estimated by differential scanning calorimetry (DSC), and a decrease of phase transition temperature was observed after polycondensation due to the disturbance of the ordered arrangement of the hydrophobic chains. The leakage rate of the vesicles before and after condensation was studied by monitoring the increase of fluorescence intensity of water-soluble dye. These vesicles belong to the least permeable ones and the leakage rate can be controlled by varying the degree of condensation or the temperature.

  20. DEFORMATION OF COPOLYMER MICELLES INDUCED BY AMPHIPHILIC DIMER PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Xiao-chun Qin; Chun-lai Ren

    2012-01-01

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

  1. Lipophosphoramidate-based bipolar amphiphiles: their syntheses and transfection properties.

    Science.gov (United States)

    Berchel, Mathieu; Le Gall, Tony; Lozach, Olivier; Haelters, Jean-Pierre; Montier, Tristan; Jaffrès, Paul-Alain

    2016-03-14

    Six new cationic bolaamphiphiles (also called bipolar amphiphiles, bolaform amphiphiles, or bolalipids) were readily prepared by a thiol-ene click reaction that engaged a mercapto-alcohol (mercapto-ethanol or mercapto-hexanol) and a cationic based lipophosphoramidate. The cationic lipophosphoramidates contain two lipid chains that end in an alkene group and a selected cationic polar head group (trimethylammonium, dimethyl hydroxyethyl ammonium, or methylimidazolium). These compounds were formulated in water (with or without DOPE as a colipid) to produce supramolecular aggregates. These aggregates, before (i.e. bolasomes) and after (i.e. bolaplexes) mixing with plasmid DNA (pDNA) at various charge ratios, were characterized with regard to their sizes and zeta potentials. In the case of bolasomes, the suspensions were unstable since precipitation occurred after only a few hours at room temperature. On the other hand, bolaplex formulations exhibited clearly a better colloidal stability. Then, the gene delivery properties of the cationic bolasomes were investigated using two human-derived epithelial cell lines (A549 and 16HBE). Compared to the commercially available lipofection reagent (Lipofectamine), most of the cationic bolaamphiphiles were able to efficiently transfect these cells when they were formulated with DOPE in a 1 : 1 molar ratio. We report herein that bolaamphiphiles possessing a trimethylammonium or a dimethyl hydroxyethyl ammonium head group were the most efficient in terms of transfection efficiency while exhibiting no significant cytotoxicity. PMID:26864681

  2. Oil industry wastewater treatment with fouling resistant membranes containing amphiphilic comb copolymers.

    Science.gov (United States)

    Asatekin, Ayse; Mayes, Anne M

    2009-06-15

    The oil industry produces large volumes of wastewater, including oil well produced water brought to the surface during oil drilling, and refinery wastewater. These streams are difficult to treat due to large concentrations of oil. Ultrafiltration (UF) is very promising for their treatment to remove oil, but has been limited by economic obstacles due to severe membrane fouling. In a recent study, novel UF membranes incorporating the amphiphilic comb copolymer additive polyacrylonitrile-graft-poly(ethylene oxide), PAN-g-PEO, were found to exhibit complete resistance to irreversible fouling by several classes of organic foulants (J. Membr. Sci. 2007, 298, 136-146). The current work focuses on application of these novel UF membranes to the treatment of oily wastewater feed streams, employing three industrial samples of oil well produced water and refinery wastewater. UF membranes cast with 20 wt % PAN-g-PEO in PAN achieved removals of dispersed and free oils of over 96% based on chemical oxygen demand (COD) for produced water samples, comparable to a PAN UF commercial membrane control. For refinery wastewater treatment the COD removal values were substantially lower, between 41 and 44%, due to higher contents of dissolved organics. Comb copolymer modified membranes showed significantly better fouling resistance than controls, recovering fully their initial fluxes after a simulated backwash for each of the three wastewater samples tested. The results indicate that UF membranes incorporating PAN-g-PEO can be cleaned completely by physical methods alone, which should extend membrane lifetimes substantially and improve the process economics for treatment of oil-contaminated waters. PMID:19603666

  3. Amphiphilic macromolecule nanoassemblies suppress smooth muscle cell proliferation and platelet adhesion.

    Science.gov (United States)

    Chan, Jennifer W; Lewis, Daniel R; Petersen, Latrisha K; Moghe, Prabhas V; Uhrich, Kathryn E

    2016-04-01

    While the development of second- and third-generation drug-eluting stents (DES) have significantly improved patient outcomes by reducing smooth muscle cell (SMC) proliferation, DES have also been associated with an increased risk of late-stent thrombosis due to delayed re-endothelialization and hypersensitivity reactions from the drug-polymer coating. Furthermore, DES anti-proliferative agents do not counteract the upstream oxidative stress that triggers the SMC proliferation cascade. In this study, we investigate biocompatible amphiphilic macromolecules (AMs) that address high oxidative lipoprotein microenvironments by competitively binding oxidized lipid receptors and suppressing SMC proliferation with minimal cytotoxicity. To determine the influence of nanoscale assembly on proliferation, micelles and nanoparticles were fabricated from AM unimers containing a phosphonate or carboxylate end-group, a sugar-based hydrophobic domain, and a hydrophilic poly(ethylene glycol) domain. The results indicate that when SMCs are exposed to high levels of oxidized lipid stimuli, nanotherapeutics inhibit lipid uptake, downregulate scavenger receptor expression, and attenuate scavenger receptor gene transcription in SMCs, and thus significantly suppress proliferation. Although both functional end-groups were similarly efficacious, nanoparticles suppressed oxidized lipid uptake and scavenger receptor expression more effectively compared to micelles, indicating the relative importance of formulation characteristics (e.g., higher localized AM concentrations and nanotherapeutic stability) in scavenger receptor binding as compared to AM end-group functionality. Furthermore, AM coatings significantly prevented platelet adhesion to metal, demonstrating its potential as an anti-platelet therapy to treat thrombosis. Thus, AM micelles and NPs can effectively repress early stage SMC proliferation and thrombosis through non-cytotoxic mechanisms, highlighting the promise of nanomedicine for

  4. New amphiphilic diblock copolymers: surfactant properties and solubilization in their micelles.

    Science.gov (United States)

    Garnier, Sébastien; Laschewsky, André

    2006-04-25

    Several series of amphiphilic diblock copolymers are investigated as macrosurfactants in comparison to reference low-molar-mass and polymeric surfactants. The various copolymers share poly(butyl acrylate) as a common hydrophobic block but are distinguished by six different hydrophilic blocks (one anionic, one cationic, and four nonionic hydrophilic blocks) with various compositions. Dynamic light scattering experiments indicate the presence of micelles over the whole concentration range from 10(-4) to 10 g x L(-1). Accordingly, the critical micellization concentrations are very low. Still, the surface tension of aqueous solutions of block copolymers decreases slowly but continuously with increasing concentration, without exhibiting a plateau. The longer the hydrophobic block, the shorter the hydrophilic block, and the less hydrophilic the monomer of the hydrophilic block is, the lower the surface tension is. However, the effects are small, and the copolymers reduce the surface tension much less than standard low-molar-mass surfactants. Also, the copolymers foam much less and even act as anti-foaming agents in classical foaming systems composed of standard surfactants. The copolymers stabilize O/W emulsions made of methyl palmitate as equally well as standard surfactants but are less efficient for O/W emulsions made of tributyrine. However, the copolymer micelles exhibit a high solubilization power for hydrophobic dyes, probably at their core-corona interface, in dependence on the initial geometry of the micelles and the composition of the block copolymers. Whereas micelles of copolymers with strongly hydrophilic blocks are stable upon solubilization, solubilization-induced micellar growth is observed for copolymers with moderately hydrophilic blocks. PMID:16618143

  5. A hybrid biomimetic scaffold composed of electrospun polycaprolactone nanofibers and self-assembled peptide amphiphile nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Tambralli, Ajay; Blakeney, Bryan; Anderson, Joel; Kushwaha, Meenakshi; Andukuri, Adinarayana; Jun, Ho-Wook [Department of Biomedical Engineering, University of Alabama at Birmingham, 801 Shelby Building, 1825 University Boulevard, Birmingham, AL 35294 (United States); Dean, Derrick [Department of Materials Science and Engineering, University of Alabama at Birmingham, BEC 254, 1150 10th Ave South, Birmingham, AL 35294 (United States)], E-mail: hwjun@uab.edu

    2009-06-01

    Nanofibrous electrospun poly ({epsilon}-caprolactone) (ePCL) scaffolds have inherent structural advantages, but lack of bioactivity has limited their usefulness in biomedical applications. Thus, here we report the development of a hybrid, nanostructured, extracellular matrix (ECM) mimicking scaffold by a combination of ePCL nanofibers and self-assembled peptide amphiphile (PA) nanofibers. The PAs have ECM mimicking characteristics including a cell adhesive ligand (RGDS) and matrix metalloproteinase-2 (MMP-2) mediated degradable sites. Transmission electron microscope imaging verified successful PA self-assembly into nanofibers (diameters of 8-10 nm) using a solvent evaporation method. This evaporation method was then used to successfully coat PAs onto ePCL nanofibers (diameters of 300-400 nm), to develop hybrid, bioactive scaffolds. Scanning electron microscope characterization showed that the PA coatings did not interfere with the porous ePCL nanofiber network. Human mesenchymal stem cells (hMSCs) were seeded onto the hybrid scaffolds to evaluate their bioactivity. Significantly greater attachment and spreading of hMSCs were observed on ePCL nanofibers coated with PA-RGDS as compared to ePCL nanofibers coated with PA-S (no cell adhesive ligand) and uncoated ePCL nanofibers. Overall, this novel strategy presents a new solution to overcome the current bioactivity challenges of electrospun scaffolds and combines the unique characteristics of ePCL nanofibers and self-assembled PA nanofibers to provide an ECM mimicking environment. This has great potential to be applied to many different electrospun scaffolds for various biomedical applications.

  6. "Cross" Supermicelles via the Hierarchical Assembly of Amphiphilic Cylindrical Triblock Comicelles.

    Science.gov (United States)

    Li, Xiaoyu; Gao, Yang; Boott, Charlotte E; Hayward, Dominic W; Harniman, Robert; Whittell, George R; Richardson, Robert M; Winnik, Mitchell A; Manners, Ian

    2016-03-30

    Self-assembled "cross" architectures are well-known in biological systems (as illustrated by chromosomes, for example); however, comparable synthetic structures are extremely rare. Herein we report an in depth study of the hierarchical assembly of the amphiphilic cylindrical P-H-P triblock comicelles with polar (P) coronal ends and a hydrophobic (H) central periphery in a selective solvent for the terminal segments which allows access to "cross" supermicelles under certain conditions. Well-defined P-H-P triblock comicelles M(PFS-b-PtBA)-b-M(PFS-b-PDMS)-b-M(PFS-b-PtBA) (M = micelle segment, PFS = polyferrocenyldimethylsilane, PtBA = poly(tert-butyl acrylate), and PDMS = polydimethylsiloxane) were created by the living crystallization-driven self-assembly (CDSA) method. By manipulating two factors in the supermicelles, namely the H segment-solvent interfacial energy (through the central H segment length, L1) and coronal steric effects (via the PtBA corona chain length in the P segment, L2 related to the degree of polymerization DP2) the aggregation of the triblock comicelles could be finely tuned. This allowed a phase-diagram to be constructed that can be extended to other triblock comicelles with different coronas on the central or end segment where "cross" supermicelles were exclusively formed under predicted conditions. Laser scanning confocal microscopy (LSCM) analysis of dye-labeled "cross" supermicelles, and block "cross" supermicelles formed by addition of a different unimer to the arm termini, provided complementary characterization to transmission electron microscopy (TEM) and dynamic light scattering (DLS) and confirmed the existence of these "cross" supermicelles as kinetically stable, micron-size colloidally stable structures in solution. PMID:26878261

  7. The Behavior of Amphiphile at Oil-Water Interface by Monte Carlo Simulation%双亲分子在油水界面的行为研究

    Institute of Scientific and Technical Information of China (English)

    潘海华; 李啸风; 李浩然; 刘迪霞; 韩世钧

    2003-01-01

    A novel simple two-dimensional square-lattice model of amphiphile at oil-water interface is developed,in which oil and water act as solvent and occupy empty sites and amphiphile occupies chains of sites. In thismodel, the oil-water interface is fixed, And amphiphile molecules will be enriched at the oil-water interface. Theinterfacial concentration of amphiphile calculated by Monte Carlo method shows that it is easier for the hydrophilic-hydrophobic balanced amphiphile to stay at the interface. And the adsorption of amphiphile increases with theincrease of amphiphile concentration and the decrease with temperature.

  8. Synthesis of Polymerizable Amphiphiles with Systematic Variation of Critical Packing Parameters

    Institute of Scientific and Technical Information of China (English)

    M. H. Li; W. L. Yang; J. Qian; C. C. Wang; S. K. Fu

    2005-01-01

    @@ 1Introduction An amphiphile is a molecule composed of hydrophilic part and hydrophobic part, which are incompatible and tend to separate from each other. The tendency of separation is often promoted by addition of water and sometimes also oil. Under balanced conditions the mixtures form macroscopically homogeneous phases, including isotropic solution phases and liquid crystalline phases. Correlation of the amphiphile structure with its preferred phases could be understood with a simple geometric model[1], which defines a dimensionless Critical Packing Parameter (CPP) to describe the relative bulkiness of the hydrophobic part and the hydrophilic part in an amphiphile. With CPP increasing from a small value to a high value the amphiphile changes from hydrophilic to hydrophobic, its preferred phase structure from direct structures via lamellar structure to reverse structures. This model provides a basis for the molecular design of amphiphiles. To immobilize the microstructure of the phases formed by amphiphiles is a challenge for current material chemists. Techniques of both inorganic polymerization[2] and organic polymerization[3] have been developed. With organic polymerization the molecular design of polymerizable amphiphiles is critical for the successful immobilization of the vulnerable precursor microstructures.

  9. Electron paramagnetic resonance study of amphiphiles partitioning behavior in desiccation-tolerant moss during dehydration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Desiccation tolerance is a crucial characteristic for desert moss surviving in arid regions. Desiccation procedure always induces amphiphiles transferring from the polar cytoplasm into lipid bodies. The behavior of amphiphiles transferring can contribute to the enhancement of desiccation tolerance and the reduction of plasma membrane integrity simultaneously. The effects of amphiphiles partitioning into the lipid phase during water loss has been studied for pollen and seeds using electron paramagnetic resonance (EPR) spectroscopy. However, desiccation-tolerant high plants occur among mosses, several angiosperms and higher plants seeds or pollens. They have different strategies for survival in dehydration and rehydration. A desiccation-tolerant moss Tortula desertorurn was used to investigate the behaviors of amphiphilic molecules during drying by spin label technology. There are small amount of amphiphilic probes partitioning into membrane during moss leaves dehydration, comparing with that in higher plants. Cytoplasm viscosity changed from 1.14 into glass state only dehydration less than 60 min. Moss leaves lost plasma membrane integrity slightly,from 0.115 to 0.237, occurred simultaneously with amphiphiles partition. The results showed the more advantages of mosses than higher plants in adapting fast dehydration. We propose that EPR spin label is feasible for studying the amphiphiles partitioning mechanisms in membrane protection and damage for desiccation-tolerant mosses.(C) 2007 Yan Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  10. Self-assembly of phosphate amphiphiles in mixtures of prebiotically plausible surfactants.

    Science.gov (United States)

    Albertsen, A N; Duffy, C D; Sutherland, J D; Monnard, P-A

    2014-06-01

    The spontaneous formation of closed bilayer structures from prebiotically plausible amphiphiles is an essential requirement for the emergence of early cells on prebiotic Earth. The sources of amphiphiles could have been both endo- and exogenous (accretion of meteorite carbonaceous material or interstellar dust particles). Among all prebiotic possible amphiphile candidates, those containing phosphate are the least investigated species because their self-assembly occurs in a seemingly too narrow range of conditions. The self-assembly of simple phosphate amphiphiles should, however, be of great interest, as contemporary membranes predominantly contain phospholipids. In contrast to common expectations, we show that these amphiphiles can be easily synthesized under prebiotically plausible environmental conditions and can efficiently form bilayer structures in the presence of various co-surfactants across a large range of pH values. Vesiculation was even observed in crude reaction mixtures that contained 1-decanol as the amphiphile precursor. The two best co-surfactants promoted vesicle formation over the entire pH range in aqueous solutions. Expanding the pH range where bilayer membranes self-assemble and remain intact is a prerequisite for the emergence of early cell-like compartments and their preservation under fluctuating environmental conditions. These mixed bilayers also retained small charged solutes, such as dyes. These results demonstrate that alkyl phosphate amphiphiles might have played a significant role as early compartment building blocks.

  11. Amphiphilic star block copolymers as gene carrier Part I: Synthesis via ATRP using calix[4]resorcinarene-based initiators and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Anna; Xue, Yan; Wei, Dafu [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Guan, Yong, E-mail: yguan@ecust.edu.cn [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Xiao, Huining [Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3 (Canada)

    2013-01-01

    In this work, a cationic star polymer [poly(2-dimethylamino)ethyl methacrylate (PDMAEMA)] was prepared via atom transfer radical polymerization (ATRP), using brominated calix[4]resorcinarene as an initiator. Hydrophobic moieties, methyl methacrylate (MMA) and butyl acrylate (BA), were further incorporated via 'one-pot' method. Well-defined eight-armed star block copolymers bearing hydrophilic blocks inside and hydrophobic blocks outside were synthesized. The molecular weight, particle size, electrophoretic mobility and apparent charge density were determined by gel permeation chromatography (GPC), dynamic light scattering (DLS), phase analysis light scattering (PALS) and colloidal titration, respectively. The zeta potentials and apparent charge densities of the products exhibited the characteristics of polyelectrolyte. The incorporation of hydrophobic moieties generated electrostatic screening effect. The as-synthesized amphiphilic star copolymer is promising as a thermo-sensitive gene carrier for gene therapy. Highlights: Black-Right-Pointing-Pointer Amphiphilic cationic star block copolymers with well-controlled structures were prepared via ATRP. Black-Right-Pointing-Pointer The molecular structures and properties of the initiator and copolymers were systematically characterized. Black-Right-Pointing-Pointer The products exhibited the positive charged character, and hydrophobic moieties generated electrostatic screening effect.

  12. Cucurbit[7]uriI-Based Vesicles Formed by Self-assembly of Supramolecular Amphiphiles

    Institute of Scientific and Technical Information of China (English)

    李佳锡; 周黎鹏; 罗全; 王永国; 张春秋; 卢伟; 徐家云; 刘俊秋

    2012-01-01

    Cucurbituril (CB), a well-known macrocyclic cavitand, has been used extensively to construct supramolecular aggregates. Based on host-guest intertactions, an adamantanyl derivative guest molecule was designed and syn- thesized to prepare a supramolecular amphiphile with cucurbit[7]uril. In aqueous solution, the cucurbit[7]uril based supramolecular amphiphiles self-assemble into well-defined vesicles, and their disassembly can be achieved by addition of excess competitive agent 1-adamantanamine hydrochloride. This vesicle functions as a new nanocapsule to encapsulate molecules within its hollow cavity. Through competitive disassembly of supramolecular amphiphiles, the vesicles behave as a novel drug delivery carrier.

  13. Syntheses, Characterization, Physical and Biological Properties of Long-chain, Water-soluble, Dendritic Amphiphiles

    OpenAIRE

    Williams, André Arvin

    2008-01-01

    In this project, we have designed and synthesized a new series of long-chain, water-soluble, dendritic, anionic amphiphiles [3CAmn, RCONHC(CH2CH2COOH)3, R= CnH2n+1] to alleviate the low aqueous solubility of fatty acids. The dendritic-tricarboxlyato headgroup improves aqueous solubility and allows us to measure the intrinsic biological activity of our amphiphiles without the potential hindrance of low aqueous solubility. The aqueous solubilities of the anionic amphiphiles have been measured...

  14. Where surface physics and fluid dynamics meet: rupture of an amphiphile layer by fluid flow

    OpenAIRE

    Bandi, Mahesh; Goldburg, Walter; Cressman Jr., John; Kellay, Hamid

    2006-01-01

    We investigate the fluctuating pattern created by a jet of fluid impingent upon an amphiphile-covered surface. This microscopically thin layer is initially covered with 50 $\\mu$m floating particles so that the layer can be visualized. A vertical jet of water located below the surface and directed upward drives a hole in this layer. The hole is particle-free and is surrounded by the particle-laden amphiphile region. The jet ruptures the amphiphile layer creating a particle-free region that is ...

  15. Large-scale dissipative particle dynamics simulations of self-assembly amphiphilic systems†

    Science.gov (United States)

    Li, Xuejin; Tang, Yu-Hang

    2014-01-01

    We present large-scale simulation results on the self-assembly of amphiphilic systems in bulk solution and under soft confinement. Self-assembled unilamellar and multilamellar vesicles are formed from amphiphilic molecules in bulk solution. The system is simulated by placing amphiphilic molecules inside large unilamellar vesicles (LUVs) and the dynamic soft confinement-induced self-assembled vesicles are investigated. Moreover, the self-assembly of sickle hemoglobin (HbS) is simulated in a crowded and fluctuating intracellular space and our results demonstrate that the HbS self-assemble into polymer fibers causing the LUV shape to be distorted. PMID:24938634

  16. Biodegradation of flax fiber reinforced poly lactic acid

    Directory of Open Access Journals (Sweden)

    2010-07-01

    Full Text Available Woven and nonwoven flax fiber reinforced poly lactic acid (PLA biocomposites were prepared with amphiphilic additives as accelerator for biodegradation. The prepared composites were buried in farmland soil for biodegradability studies. Loss in weight of the biodegraded composite samples was determined at different time intervals. The surface morphology of the biodegraded composites was studied with scanning electron microscope (SEM. Results indicated that in presence of mandelic acid, the composites showed accelerated biodegradation with 20–25% loss in weight after 50–60 days. On the other hand, in presence of dicumyl peroxide (as additive, biodegradation of the composites was relatively slow as confirmed by only 5–10% loss in weight even after 80–90 days. This was further confirmed by surface morphology of the biodegraded composites. We have attempted to show that depending on the end uses, we can add different amphiphilic additives for delayed or accelerated biodegradability. This work gives us the idea of biodegradation of materials from natural fiber reinforced PLA composites when discarded carelessly in the environment instead of proper waste disposal site.

  17. Preparation of pH-sensitive amphiphilic block star polymers, their self-assembling characteristics and release behavior on encapsulated molecules

    KAUST Repository

    Song, Xiaowan

    2016-05-28

    Poly(ethylene glycol) (PEG), a polymer with excellent biocompatibility, was widely used to form nanoparticles for drug delivery applications. In this paper, based on PEG, a series of pH-sensitive amphiphilic block star polymers of poly(ethylene glycol)-block-poly(ethoxy ethyl glycidyl ether) (PEG-b-PEEGE) with different hydrophobic length were synthesized by living anionic ring-opening polymerization method. The products were characterized using 1H NMR and gel permeation chromatography. These copolymers could self-assemble in aqueous solution to form micellar structure with controlled morphologies. Transmission electron microscopy showed that the nanoparticles are spherical or rodlike with different hydrophilic mass fractions. The pH response of polymeric aggregates from PEG-b-PEEGE was detected by fluorescence probe technique at different pH. A pH-dependent release behavior was observed and pH-responsiveness of PEG-b-PEEGE was affected by the hydrophobic block length. These results demonstrated that star-shaped polymers (PEG-b-PEEGE) are attractive candidates as anticancer drug delivery carriers. © 2016 Springer-Verlag Berlin Heidelberg

  18. Physical and Chemical Characterization of Poly(hexamethylene biguanide Hydrochloride

    Directory of Open Access Journals (Sweden)

    Luiz Henrique C. Mattoso

    2011-06-01

    Full Text Available We present the characterization of commercially available Poly(hexamethylene biguanide hydrochloride (PHMB, a polymer with biocidal activity and several interesting properties that make this material suitable as a building block for supramolecular chemistry and “smart” materials. We studied polymer structure in water solution by dynamic light scattering, surface tension and capacitance spectroscopy. It shows typical surfactant behavior due to amphiphilic structure and low molecular weight. Spectroscopic (UV/Vis, FT-NIR and thermal characterization (differential scanning calorimetry, DSC, and thermogravimetric analysis, TGA were performed to give additional insight into the material structure in solution and solid state. These results can be the foundation for more detailed investigations on usefulness of PHMB in new complex materials and devices.

  19. [Study of novel artificial lung surfactants incorporating partially fluorinated amphiphiles].

    Science.gov (United States)

    Nakahara, Hiromichi

    2012-01-01

    Lung surfactants (LS), a complex of ∼90 wt% lipids (mainly dipalmitoylphosphatidylcholine or DPPC) and ∼10 wt% surfactant proteins (SP-A, -B, -C, and -D), adsorb to an air-alveolar fluid interface and then lower its surface tension down to near zero during expiration. Intratracheal instillation of exogenous LS preparations can effectively compensate for surfactant deficiency in premature infants with respiratory distress syndrome (RDS). Surfacten® (Mitsubishi Tanabe Pharma Corporation, Osaka, Japan), a modified bovine lung extract and an effective surfactant replacement in treatment for RDS patients, is supplemented with DPPC, palmitic acid, and tripalmitin. For the premature infants suffering from RDS, instillation of Surfacten® leads to a dramatic improvement in lung function and compliance. Herein, the author reviews potential use of newly designed preparations containing a mimicking peptide of SP-B and also introduces the current research on the preparations incorporated with partially fluorinated amphiphiles to improve their efficacy. PMID:22790027

  20. Supramolecular chirality in self-assembled peptide amphiphile nanostructures.

    Science.gov (United States)

    Garifullin, Ruslan; Guler, Mustafa O

    2015-08-11

    Induced supramolecular chirality was investigated in the self-assembled peptide amphiphile (PA) nanosystems. Having shown that peptide chirality can be transferred to the covalently-attached achiral pyrene moiety upon PA self-assembly, the chiral information is transferred to molecular pyrene via weak noncovalent interactions. In the first design of a supramolecular chiral system, the chromophore was covalently attached to a peptide sequence (VVAGH) via an ε-aminohexanoic acid spacer. Covalent attachment yielded a PA molecule self-assembling into nanofibers. In the second design, the chromophore was encapsulated within the hydrophobic core of self-assembled nanofibers of another PA consisting of the same peptide sequence attached to lauric acid. We observed that supramolecular chirality was induced in the chromophore by PA assembly into chiral nanostructures, whether it was covalently attached, or noncovalently bound. PMID:26146021

  1. Structure and reactivity in amphiphile-water micelles

    International Nuclear Information System (INIS)

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

  2. Amphiphilic siderophore production by oil-associating microbes.

    Science.gov (United States)

    Kem, Michelle P; Zane, Hannah K; Springer, Stephen D; Gauglitz, Julia M; Butler, Alison

    2014-06-01

    The Deepwater Horizon oil spill in 2010 released an unprecedented amount of oil into the ocean waters of the Gulf of Mexico. As a consequence, bioremediation by oil-degrading microbes has been a topic of increased focus. One factor limiting the rate of hydrocarbon degradation by microbial communities is the availability of necessary nutrients, including iron. The siderophores produced from two Vibrio spp. isolated from the Gulf of Mexico following the Deepwater Horizon oil spill, along with the well-studied oil-degrading microbe, Alcanivorax borkumensis SK2, are studied under iron-limiting conditions. Here we report the amphiphilic amphibactin siderophores produced by the oil-associated bacteria, Vibrio sp. S1B, Vibrio sp. S2A and Alcanivorax borkumensis SK2. These findings provide insight into oil-associating microbial iron acquisition. PMID:24663669

  3. Antifungal amphiphilic aminoglycoside K20: bioactivities and mechanism of action

    Directory of Open Access Journals (Sweden)

    Sanjib K. Shrestha

    2014-12-01

    Full Text Available K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20’s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were determined. Effects on Cryptococcus neoformans H-99 infectivity were determined with a preventive murine lung infection model. The antifungal mechanism of action was studied using intact fungal cells, yeast lipid mutants, and small unilamellar lipid vesicles. K20 exhibited broad-spectrum in vitro antifungal activities but not antibacterial activities. Pulmonary, single dose-administration of K20 reduced C. neoformans lung infection rates 4-fold compared to controls. Hemolysis and half-maximal cytotoxicities of mammalian cells occurred at concentrations that were 10 to 32-fold higher than fungicidal MICs. With fluorescein isothiocyanate, 20 to 25 mg/L K20 caused staining of >95% of C. neoformans and Fusarium graminearum cells and at 31.3 mg/L caused rapid leakage (30 to 80% in 15 min of calcein from preloaded small unilamellar lipid vesicles. K20 appears to be a broad-spectrum fungicide, capable of reducing the infectivity of C. neoformans, and exhibits low hemolytic activity and mammalian cell toxicity. It perturbs the plasma membrane by mechanisms that are lipid modulated. K20 is a novel amphiphilic aminoglycoside amenable to scalable production and a potential lead antifungal for therapeutic and crop protection applications.

  4. Globules of annealed amphiphilic copolymers: Surface structure and interactions

    Science.gov (United States)

    Jarkova, E.; Johner, A.; Maresov, E. A.; Semenov, A. N.

    2006-12-01

    A mean-field theory of globules of random amphiphilic copolymers in selective solvents is developed for the case of an annealed copolymer sequence: each unit can be in one of two states, H (insoluble) or P (soluble or less insoluble). The study is focussed on the regime when H and P units tend to form long blocks, and when P units dominate in the dilute phase, but are rare in the globule core. A first-order coil-to-globule transition is predicted at some T = Tcg. The globule core density at the transition point increases as the affinity of P units to the solvent, tildeɛ, is increased. Two collapse transitions, coil → “loose” globule and “loose” globule → “dense” globule, are predicted if tildeɛ is high enough and P units are marginally soluble or weakly insoluble. H and P concentration profiles near the globule surface are obtained and analyzed in detail. It is shown that the surface excess of P units rises as tildeɛ is increased. The surface tension decreases in parallel. Considering the interaction between close enough surfaces of two globules, we show that they always attract each other at a complete equilibrium. It is pointed out, however, that such equilibrium may be difficult to reach, so that partially equilibrium structures (defined by the condition that a chain forming one globule does not penetrate into the core of the other globule) are relevant. It is shown that at such partial equilibrium the interaction is repulsive, so the globules may be stabilized from aggregation. The strongest repulsion is predicted at the coil-to-globule transition point Tcg: the repulsion force decreases with the distance between the surfaces according to a power law. In the general case (apart from Tcg) the force vs. distance decay becomes exponential; the decay length ξ diverges as T → Tcg. The developed theory explains certain anomalous properties observed for globules of amphiphilic homopolymers.

  5. Preparation and Characterization of Nimodipine-loaded Methoxy Poly (ethylene glycol)-poly (lactic acid) Diblock Copolymer Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    ZHA Liu-sheng; LI Lan; ZHAO Hui-peng

    2006-01-01

    Amphiphilic diblock copolymers, methoxy poly (ethylene glycol)-poly(lactic acid) (MePEG-PLA), were synthesized from monomers of DL-lactide and methoxy poly (ethylene glycol) by a ring opening bulk polymerization in the presence of stannous octoate. Their chemical structure and physical properties were investigated using FTIR, NMR, GPC, and fluorescence spectroscopy. To estimate the feasibility as colloidal drug carrier, nimodipine (ND) was loaded into MePEG-PLA block copolymer nanoparticles by phaseseparation/dialysis method. The mean diameter and drug loading efficiency of ND-loaded MePEG-PLA copolymer nanoparticles depended on PLA/MePEG block composition of the copolymer and drug/polymer feed ratio in preparation. NMR study confirmed that nimodipine was entrapped into the hydrophobic inner core of MePEG-PLA copolymer nanoparticles and hydrophilic PEG chains were located on the surface of the drug-loaded polymer nanoparticles. In vitro release experiments exhibited the sustained release behavior of nimodipine from MePEG-PLA copolymer nanoparticles, without any burst effect.

  6. Stability of Water/Poly(ethylene oxide)43-b-poly(ε-caprolactone)14/Cyclohexanone Emulsions Involves Water Exchange between the Core and the Bulk.

    Science.gov (United States)

    Flores, Mario E; Martínez, Francisco; Olea, Andrés F; Shibue, Toshimichi; Sugimura, Natsuhiko; Nishide, Hiroyuki; Moreno-Villoslada, Ignacio

    2015-12-31

    The formation of emulsions upon reverse self-association of the monodisperse amphiphilic block copolymer poly(ethylene oxide)43-b-poly(ε-caprolactone)14 in cyclohexanone is reported. Such emulsions are not formed in toluene, chloroform, or dichloromethane. We demonstrate by magnetic resonance spectroscopy the active role of the solvent on the stabilization of the emulsions. Cyclohexanone shows high affinity for both blocks, as predicted by the Hansen solubility parameters, so that the copolymer chains are fully dissolved as monomeric chains. In addition, the solvent is able to produce hydrogen bonding with water molecules. Water undergoes molecular exchange between water molecules associated with the polymer and water molecules associated with the solvent, dynamics of major importance for the stabilization of the emulsions. Association of polymeric chains forming reverse aggregates is induced by water over a concentration threshold of 5 wt %. Reverse copolymer aggregates show submicron average hydrodynamic diameters, as seen by dynamic light scattering, depending on the polymer and water concentration.

  7. Nucleoside, nucleotide and oligonucleotide based amphiphiles: a successful marriage of nucleic acids with lipids.

    Science.gov (United States)

    Gissot, Arnaud; Camplo, Michel; Grinstaff, Mark W; Barthélémy, Philippe

    2008-04-21

    Amphiphilic molecules based on nucleosides, nucleotides and oligonucleotides are finding more and more biotechnological applications. This Perspective highlights their synthesis, supramolecular organization as well as their applications in the field of biotechnology.

  8. Amphiphile regulation of ion channel function by changes in the bilayer spring constant

    DEFF Research Database (Denmark)

    Lundbæk, Jens August; Koeppe, R.E.; Andersen, Oluf Sten

    2010-01-01

    effect of amphiphiles, at concentrations often used in biological research, on the bilayer elastic response to a change in the hydrophobic length of an embedded protein. The effects of structurally diverse amphiphiles can be described by changes in a phenomenological bilayer spring constant (H......Many drugs are amphiphiles that, in addition to binding to a particular target protein, adsorb to cell membrane lipid bilayers and alter intrinsic bilayer physical properties (e. g., bilayer thickness, monolayer curvature, and elastic moduli). Such changes can modulate membrane protein function......-B) that summarizes the bilayer elastic properties, as sensed by a bilayer-spanning protein. Amphiphile-induced changes in H-B, measured using gA channels of a particular length, quantitatively predict changes in lifetime for channels of a different length-as well as changes in the inactivation of voltage...

  9. Amphiphilic organoplatinum(II) complexes: Self-assembly in solution and at interfaces

    Science.gov (United States)

    Maran, Umamageswaran

    Organoplatinum(II) gemini amphiphiles with three different chain lengths and a predefined angle of 60° are synthesized. Self-organization at the air-water interface is investigated as a function of chain length and reduction in surface area, by using Langmuir-trough techniques. The atomic force microscopy (AFM) images of the transferred Langmuir-Schaefer (LS) films reveals wormlike aggregates for the organoplatinum(II) gemini amphiphiles, possessing hexyloxy- and dodecyloxy-chains. A neutral crown ether functionalized [1+1] facial amphiphile was self-assembled from a flexible 32-membered dibenzo crown ether and a diplatinum acceptor clip. A homologous series of charged triangle-shaped amphiphilic metallomacrocyles was self-assembled from stoichiometric amounts of organoplatinum(II) gemini amphiphiles and bipyridyl donor molecules in quantitative yields. The amphiphilic triangular scaffolds were characterized by multinuclear NMR and ESI-MS. A new amphiphilic organoplatinum(II) precursor with a predefined angle of 90° was synthesized. The precursor was mixed in stoichiometric ratios with two different 3-substituted pyridines and a rigid bipyridyl ligand to construct three charged amphiphilic metallomacrocyles. The computational calculations on the assemblies constructed from flexible 3-substituted pyridines indicate that the assemblies exist largely as chair isomers. The self-organization of the hexacationic triangular amphiphiles at liquid-liquid, air-water and solid-air interfaces was studied using confocal microscopy, in situ Raman spectroscopy, Langmuir-trough techniques, fluorescence spectroscopy and AFM. The amphiphilic triangle with octadecyloxy-chains was found to form a bicontinuous coacervate with pores in a chloroform/water solvent mixture. The pressure-area isotherms revealed formation of surface aggregates at the air-water interface. Fluid AFM studies on the transferred LS layers reveal ridge-like patterns with a flat top. Models were constructed to

  10. Amphiphilic oligoethyleneimine-β-cyclodextrin "click" clusters for enhanced DNA delivery.

    Science.gov (United States)

    Martínez, Álvaro; Bienvenu, Céline; Jiménez Blanco, José L; Vierling, Pierre; Mellet, Carmen Ortiz; García Fernández, José M; Di Giorgio, Christophe

    2013-08-16

    Monodisperse amphiphilic oligoethyleneimine (OEI)-β-cyclodextrin (βCD) clusters have been prepared, and their potential as gene delivery systems has been evaluated in comparison with a nonamphiphilic congener. The general prototype incorporates tetraethyleneimine segments linked to the primary rim of βCD through either triazolyl or thioureidocysteaminyl connectors. Transfection efficiency data for the corresponding CD:pDNA nanocomplexes (CDplexes) in BNL-CL2 murine hepatocytes evidenced the strong beneficial effect of facial amphiphilicity. PMID:23859761

  11. Synthesis and aggregation properties of amphiphilic mono and bisadducts of fullerene in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    Pu Zhang; Zhi Xin Guo; Shuang Lv

    2008-01-01

    New amphiphilic[60]fullerene monoadduet TPF and bisadducts BTPF were synthesized and well-characterized. Their aggregation properties in aqueous solution was investigated by UV-vis and TEM methods. In aqueous solution, monoadduct TPF forms irregularly shaped and some rod-like aggregates, whereas bisadducts BTPF gives spherical aggregates with diameters of 50-150 nm. It indicated that the aggregation properties of amphiphilic fullerene derivatives depend on the number of hydrophilic appendage on the C60 cage.

  12. AN APPROACH TO SYNTHESIZE POLY(ETHYLENE GLYCOL)-b-POLY(ε-CAPROLACTONE) WITH TERMINAL AMINO GROUP via SCHIFF'S BASE AS AN INITIATOR

    Institute of Scientific and Technical Information of China (English)

    Li Chen; Xiu-li Zhuang; Guo-en Sun; Xue-si Chen; Xia-bin Jing

    2008-01-01

    A new method to synthesize a degradable terminal amino group-containing copolymer, poly(ethylene glycol)-b-poly(ε-caprolactone) (MPEG-PCL-NH2), was developed in the following three steps: (1) the ring-opening polymerization (ROP) of ε-caprolactone from the Schiff base prepared from benzaldehyde and ethanolamine (Ph-CH=NCH2CH2OH) used as an initiator to obtain heterobifunctional poly(ε-caprolactone) with one terminal Schiff base group and one hydroxyl group (HO-PCL-CH2CH2N = CH-Ph); (2) the coupling reaction of two reactive precursors, a hydroxy-terminated HO-PCL-CH2CH2N=CH-Ph and α-monocarboxy-ωmonomethoxy poly(ethylene glycol) (CMPEG) to synthesize MPEG-PCL-CH2CH2N=CH-Ph; (3) the conversion of the -N=CH-Ph end-group into NH2 end-group by acidification of acetic acid to obtain MPEG-PCL-NH2. The structures from the precursors to the terminal amino group-containing copolymer were confirmed by 1H-NMR and their molecular weights were measured by gel permeation chromatography. The amphiphilic terminal amino group-containing copolymer could self-assemble into micelles in an aqueous system with PCL block as the core and PEG block as the shell. The micelle formation of the terminal amino group-containing block copolymer was studied by fluorescent probe technique and the existence of critical micellar concentration (cmc) confirmed the amphiphilic nature of the resulting copolymer. ESEM and DLS analysis of the micelles revealed a homogeneous spherical morphology and a unimodal size distribution.

  13. Amphiphile self-assemblies in supercritical CO2 and ionic liquids.

    Science.gov (United States)

    Zhang, Jianling; Peng, Li; Han, Buxing

    2014-08-28

    Supercritical (sc) CO2 and ionic liquids (ILs) are very attractive green solvents with tunable properties. Using scCO2 and ILs as alternatives of conventional solvents (water and oil) for forming amphiphile self-assemblies has many advantages. For example, the properties and structures of the amphiphile self-assemblies in these solvents can be easily modulated by tuning the properties of solvents; scCO2 has excellent solvation power and mass-transfer characteristics; ILs can dissolve both organic and inorganic substances and their properties are designable to satisfy the requirements of various applications. Therefore, the amphiphile self-assemblies in scCO2 and ILs have attracted considerable attention in recent years. This review describes the advances of using scCO2 or/and ILs as amphiphile self-assembly media in the last decade. The amphiphile self-assemblies in scCO2 and ILs are first reviewed, followed by the discussion on combination of scCO2 and ILs in creating microemulsions or emulsions. Some future directions on the amphiphile self-assemblies in scCO2 and ILs are highlighted. PMID:25000970

  14. Redox-sensitive micelles assembled from amphiphilic mPEG-PCL-SS-DTX conjugates for the delivery of docetaxel.

    Science.gov (United States)

    Zhang, Huiyuan; Wang, Kaiming; Zhang, Pei; He, Wenxiu; Song, Aixin; Luan, Yuxia

    2016-06-01

    Docetaxel (DTX) can produce anti-tumor effects by inhibiting cell growth and inducing apoptosis. However, the poor solubility of DTX restricts its application and its clinical formulation has caused serious adverse reaction due to the use of Tween-80. In the present study, DTX was conjugated to an amphiphilic di-block polymer to solve these problems. Methoxy poly(ethylene glycol)-poly(ε-caprolactone) (mPEG-PCL) was selected as the polymer skeleton and a redox sensitive disulfide bond was used as the linker between DTX and mPEG-PCL. The synthesized mPEG-PCL-SS-DTX conjugates were characterized by (1)H-nuclear magnetic resonance ((1)H NMR) and Fourier transform infrared spectroscopy (FTIR). Interestingly, the mPEG-PCL-SS-DTX conjugates could self-assemble into micelles in aqueous solution. The critical micelle concentration (CMC) of mPEG-PCL-SS-DTX micelles was about 2.3mgL(-1) determined using pyrene molecule fluorescent probe method while the size of mPEG-PCL-SS-DTX micelles was determined to be ca. 17.6nm and 116.0nm with a bimodal distribution by dynamic light scattering (DLS). The in vitro release results indicated that the as-prepared micelles exhibited a sustained release profile with good redox sensitive properties. In particular, the hemolytic toxicity test indicated the as-prepared mPEG-PCL-SS-DTX micelles had negligible hemolytic activity, demonstrating their safety in drug delivery system. Cytotoxicity assay of the mPEG-PCL-SS-DTX micelles verified their highly enhanced cytotoxicity to MCF-7/A and A549 cells. These results thus demonstrated that the present redox-sensitive mPEG-PCL-SS-DTX micelle was an efficient and safe sustained drug delivery system in the biomedical area.

  15. Amphiphilic Copolymeric Micelles for Doxorubicin and Curcumin Co-Delivery to Reverse Multidrug Resistance in Breast Cancer.

    Science.gov (United States)

    Lv, Li; Qiu, Kaifeng; Yu, Xiaoxia; Chen, Chuxiong; Qin, Fengchao; Shi, Yonghui; Ou, Jiebin; Zhang, Tao; Zhu, Hua; Wu, Junyan; Liu, Chunxia; Li, Guocheng

    2016-05-01

    Development of multidrug resistance against chemotherapeutic drugs is one of the major obstacles to successful cancer therapy in the clinic. Thus far, amphiphilic polymeric micelles and chemosensitizers have been used to overcome multidrug resistance in cancer. The goals of this study were to prepare poly(ethylene glycol)-bock-poly(lactide) (PEG(2k)-PLA(5k)) micelles for co-delivery of the chemotherapeutic drug doxorubicin (DOX) with a chemosensitizer curcumin (CUR), investigate the potential of the dual drug-loaded micelles ((DOX+CUR)-Micelles) to reverse multidrug resistance, and explore the underlying mechanisms. (DOX + CUR)-Micelles were prepared using an emulsion solvent evaporation method. The cellular uptake, drug efflux, down-regulation of P-glycoprotein expression and inhibition of ATP activity of (DOX+ CUR)-Micelles were studied in drug-resistant MCF-7/ADR cells. In vitro analyses demonstrated that (DOX + CUR)-Micelles were superior to free DOX, free drug combination (DOX + CUR), and DOX-loaded micelles in inhibiting proliferation of MCF-7/ADR cells. This effect of (DOX + CUR)-Micelles was partially attributable to their highest cellular uptake, lowest efflux rate of DOX, and strongest effects on down-regulation of P-glycoprotein and inhibition of ATP activity. Additionally, (DOX+CUR)-Micelles showed increased tumor accumulation and strong inhibitory effect on tumor growth in the xenograft model of drug-resistant MCF-7/ADR cells compared to that of other drug formulations. These results indicate that (DOX + CUR)-Micelles display potential for application in the therapy of drug-resistant breast carcinoma. PMID:27305819

  16. Was Every Polis State Centred on a Polis Town?

    DEFF Research Database (Denmark)

    Hansen, Mogens Hermann

    2007-01-01

    Ordet polis i betydningen stat bruges i arkaiske og klassiske kilder udelukkende om en stat, der havde en polis i betydningen by som sit urbane centrum In Archaic and Classical sources the word polis in the sense of state was  invariably used about a state that was centred on a polis in the urban...

  17. Was Every Polis Town the Centre of a Polis State?

    DEFF Research Database (Denmark)

    Hansen, Mogens Hermann

    2007-01-01

    Ordet polis i betydningen by bruges i arkaiske og klassiske kilder udelukkende om en by, der samtidig var det urbane centrum for en polis i betydningen stat. In archaic and Classical sources the word polis in the sense of city  is invariably used about a city which was the urban centre of a polis...

  18. Tunable Nanocarrier Morphologies from Glycopolypeptide-based Amphiphilic Biocompatible Star Copolymers and Their Carbohydrate Specific Intracellular Delivery

    KAUST Repository

    Pati, Debasis

    2015-12-21

    Nano-carriers with carbohydrates on the surface represent a very interesting class of drug delivery vehicles since carbohydrates are involved in bio-molecular recognition events in vivo. We have synthesized biocompatible miktoarm star copolymers comprising glycopolypeptide and poly(ε-caprolactone) chains, using ring opening polymerization and ‘click chemistry’. The amphiphilic copolymers were self-assembled in water into morphologies such as nanorods, polymersomes and micelles with carbohydrates displayed on the surface. We demonstrate that, the formation of nanostructure could be tuned by chain length of the blocks and was not affected by the type of sugar residue. These nanostructures were characterized in detail using a variety of techniques such as TEM, AFM, cryogenic electron microscopy, spectrally resolved fluorescence imaging and dye encapsulation techniques. We show that it is possible to sequester both hydrophobic as well as hydrophilic dyes within the nanostructures. Finally, we show that these non-cytotoxic manno-sylated rods and polymersomes were selectively and efficiently taken up by MDA-MB-231 breast cancer cells demonstrating their potential as nanocarriers for drug delivery.

  19. Protein Modification with Amphiphilic Block Copoly(2-oxazoline)s as a New Platform for Enhanced Cellular Delivery

    KAUST Repository

    Tong, Jing

    2010-08-02

    Several homopolymers, random copolymers and block copolymers based on poly(2-oxazoline)s (POx) were synthesized and conjugated to horseradish peroxidase (HRP) using biodegradable and nonbiodegradable linkers. These conjugates were characterized by amino group titration, polyacrylamide gel electrophoresis (PAGE), isoelectric focusing, enzymatic activity assay and conformation analysis. The conjugates contained on average from about one to two polymer chains per enzyme. From 70% to 90% of enzymatic activity was retained in most cases. Circular dichroism (CD) analysis revealed that HRP modification affected the secondary structure of the apoprotein but did not affect the tertiary structure and heme environment. Enhanced cellular uptake was found in the conjugates of two block copolymers using both MDCK cells and Caco-2 cells, but not in the conjugates of random copolymer and homopolymer. Conjugation with a block copolymer of 2-methyl-2-oxazoline and 2-butyl-2-oxazoline led to the highest cellular uptake as compared to other conjugates. Our data indicates that modification with amphiphilic POx has the potential to modulate and enhance cellular delivery of proteins.

  20. Magnetic core–bilayer shell complex of magnetite nanoparticle stabilized with mPEG–polyester amphiphilic block copolymer

    International Nuclear Information System (INIS)

    In this article, we report the synthesis of magnetite nanoparticles (Fe3O4) coated with methoxy poly(ethylene glycol) (mPEG)–polyester amphiphilic block copolymers. The coating polymer layer contains a hydrophobic inner layer of polyester and a hydrophilic corona of mPEG. The copolymers were first prepared via a direct condensation between diacid, diol compounds and mPEG oligomer to obtain a hydrophobic polyester block and hydrophilic mPEG block and then “grafted onto” a magnetite nanoparticle surface. The copolymer composition was varied by changing the structure of the diacid, diol, and the molecular weight ( M-bar n ) of the mPEG such that particles with good dispersibility and stability in water were obtained. It was found that the copolymer prepared from 1,6-hexanediol can effectively stabilize the particles in water regardless of the types of diacid and M-bar n of mPEG used. The particle size was approximately 10 nm in diameter, and the particle dispersibility in water was quite dependent on the type and concentration of the copolymer used. Thermogravimetric analysis revealed the presence of less than 37 % Fe3O4 and about 48–53 % of the copolymer in the complexes. The percent entrapment efficiency and loading efficiency of indomethacin model drug in the copolymer-coated magnetite nanoparticles were 19 and 77 %, respectively

  1. The synthesis of spherical calcium carbonate composite in amphiphilic PS-b-PAA solution and its thermal dynamic characteristic

    Institute of Scientific and Technical Information of China (English)

    YUE Linhai; JIN Dalai

    2004-01-01

    Spherical calcium carbonate composite is synthesized in the solution of amphiphilic block copolymer of polystyrene(PS) and poly(acrylic acid)(PAA). SEM and XRD measurements show that the diameter of the particulates decreases with the augment of the PS-b-PAA concentration, crystalline in the composite is calcite and its morphology as well as the structure is changed too. TG-DTA together with IR analysis is applied to investigating the thermal dynamic behavior of the composite. The results show that the composite is mainly composed of two phases, that is, the nano- crystalline calcium carbonate and the PS-b-PA-Ca composites. PS phase decomposes first with a large heat release at about 330℃. However, the PAA chains have relatively high thermal stability, probably due to the structural Ca-O bond, and decomposes at above 400℃. Matching opinions are used to explain the possible reasons for the regular as well as the particular characteristics of the composite corresponding to a certain copolymer concentration.

  2. Preparation of amphiphilic glycopolymers with flexible long side chain and their use as stabilizer for emulsion polymerization.

    Science.gov (United States)

    Alvárez-Paino, Marta; Juan-Rodríguez, Rafael; Cuervo-Rodríguez, Rocío; Muñoz-Bonilla, Alexandra; Fernández-García, Marta

    2014-03-01

    A glycomonomer was synthesized from poly(ethylene glycol) methacrylate (PEGMA). The terminal hydroxyl moieties were activated with ester groups and subsequently the glucosamine was incorporated forming urethane linkages. The obtained glycomonomer was copolymerized with methyl acrylate by free radical polymerization varying the initial feed composition to produce different amphiphilic glycopolymers. The glycopolymers were then characterized and compared with the homologous glycopolymers based on 2-{[(D-glucosamin-2-N-yl)carbonyl]oxy}ethyl methacrylate. Both series of glycopolymers were used in emulsion polymerization of methyl acrylate as stabilizers without the addition of any cosurfactant. Although high conversions were not achieved with any of the employed surfactant, the glycopolymers provide good colloidal stability, spherical, monodisperse and small latex particles in comparison with the surfactant-free emulsion polymerization. The latex particles stabilized with the glycosurfactant based on PEGMA, containing a flexible spacer between the backbone and the glucosamine, lead to smooth films whereas the short side chain surfactant from 2-hydroxyethyl methacrylate (HEMA), with higher glass transition temperature, restricts the coalescence of particles and, therefore, the film formation. Moreover, the surface bioactivity of these polymer coatings was examined by analyzing their specific interaction with the lectin, Concanavalin A, Canavalia ensiformis. The specific and successful binding to the Concanavalin A was demonstrated by fluorescence microscopy for both series being more intense with increasing amount of glycounits in the glycopolymer stabilizers. Interestingly, the incorporation of a flexible spacer in the glycopolymer structures enhances the binding activity.

  3. Magnetic core–bilayer shell complex of magnetite nanoparticle stabilized with mPEG–polyester amphiphilic block copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Mekkapat, Supachai; Thong-On, Bandit; Rutnakornpituk, Boonjira; Wichai, Uthai; Rutnakornpituk, Metha, E-mail: methar@nu.ac.th [Naresuan University, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science (Thailand)

    2013-11-15

    In this article, we report the synthesis of magnetite nanoparticles (Fe{sub 3}O{sub 4}) coated with methoxy poly(ethylene glycol) (mPEG)–polyester amphiphilic block copolymers. The coating polymer layer contains a hydrophobic inner layer of polyester and a hydrophilic corona of mPEG. The copolymers were first prepared via a direct condensation between diacid, diol compounds and mPEG oligomer to obtain a hydrophobic polyester block and hydrophilic mPEG block and then “grafted onto” a magnetite nanoparticle surface. The copolymer composition was varied by changing the structure of the diacid, diol, and the molecular weight ( M-bar {sub n} ) of the mPEG such that particles with good dispersibility and stability in water were obtained. It was found that the copolymer prepared from 1,6-hexanediol can effectively stabilize the particles in water regardless of the types of diacid and M-bar {sub n} of mPEG used. The particle size was approximately 10 nm in diameter, and the particle dispersibility in water was quite dependent on the type and concentration of the copolymer used. Thermogravimetric analysis revealed the presence of less than 37 % Fe{sub 3}O{sub 4} and about 48–53 % of the copolymer in the complexes. The percent entrapment efficiency and loading efficiency of indomethacin model drug in the copolymer-coated magnetite nanoparticles were 19 and 77 %, respectively.

  4. Synthesis of antibacterial amphiphilic elastomer based on polystyrene-block-polyisoprene-block-polystyrene via thiol-ene addition

    Energy Technology Data Exchange (ETDEWEB)

    Keleş, Elif, E-mail: elifkelesh@hotmail.com [Department of Chemistry, Bülent Ecevit University, Zonguldak 67100 (Turkey); Hazer, Baki, E-mail: bhazer2@yahoo.com [Department of Chemistry, Bülent Ecevit University, Zonguldak 67100 (Turkey); Cömert, Füsun B. [Department of Microbiology, Faculty of Medicine, Bülent Ecevit University, 67600 Zonguldak (Turkey)

    2013-04-01

    A new type of amphiphilic antibacterial elastomer has been described. Thermoplastic elastomer, polystyrene–block-polyisoprene–block-polystyrene (PS–b-PI–b-PS) triblock copolymer was functionalized in toluene solution by free radical mercaptan addition in order to obtain an amphiphilic antibacterial elastomer. Thiol terminated PEG was grafted through the double bonds of PS–b-PI–b-PS via free radical thiol-ene coupling reaction. The antibacterial properties of the amphiphilic graft copolymers were observed. The original and the modified polymers were used to create microfibers in an electro-spinning process. Topology of the electrospun micro/nanofibers were studied by using scanning electron microscopy (SEM). The chemical structures of the amphiphilic comb type graft copolymers were elucidated by the combination of elemental analysis, {sup 1}H NMR, {sup 13}C NMR, GPC and FTIR. - Graphical abstract: Double bonds of polyisoprene units in polystyrene–block-polyisoprene–block-polystyrene triblock copolymer were partially capped with PEG containing mercapto end group via thiol-ene addition in order to obtain antibacterial amphiphilic elastomer. Nano fibers from amphiphilic graft polymers solution were produced by electrospinning. The PEG grafted copolymer inhibits very effectively bacterial growth. Highlights: ► A commercial synthetic elastomer was grafted with PEG to obtain amphiphilic elastomer. ► Amphiphilic elastomer shows antibacterial properties. ► Electrospun micro fibers of the amphiphilic elastomer tend to globular formation.

  5. Manipulating the morphologies of poly(vinyl alcohol) block copolymer surfactants

    Science.gov (United States)

    Repollet-Pedrosa, Milton H.

    Amphiphilic block copolymers (ABCs) are macromolecules containing well-defined hydrophilic and hydrophobic segments that self-assemble into nanoscale aggregates such as spherical and cylindrical micelles and vesicles, when dispersed in block-selective solvents. ABCs possess a miniscule critical micelle concentration, which results in kinetically trapped and persistent assemblies in solution with slow chain exchange between aggregates. This makes them useful as rheological modifiers for personal care products, enhanced oil recovery, and drug delivery formulations. Their utility in many of these applications is crucially dependent on the ability to control the micellar morphologies that they adopt in selective solvents. Triggering ABC micellar morphological transformations, i.e. from spherical to cylindrical micelles, is important for generating "on-demand" stimuli-responsive morphologies that control the aggregate morphology and the bulk solution properties in any given application. In this thesis, we develop the straightforward synthesis of biodegradable and biocompatible ABCs comprised of poly(vinyl acetate) (PVAc) and poly(vinyl alcohol) (PVA), with narrow molecular distributions and variable yet well-defined compositions. These block copolymer amphiphiles readily form spherical micelles in aqueous dispersions. We demonstrate that the addition of a water-soluble poly(ethylene oxide) (PEO) homopolymer to these dispersions results in a rapid transformation of these spherical micelles into cylindrical micelles. Dilution of these cylindrical micelles with water induces their reversion to spherical micelles. Our results indicate that the reversible morphology change depends sensitively on the PEO homopolymer concentration and molecular weight, as well as the length of the PVA corona block of the micelles. Through a series of quantitative 1H NMR studies, we found that the preferential partitioning of PEO homopolymer into the PVAc micellar core drives this morphological

  6. Bioinspired Poly(2-oxazolines

    Directory of Open Access Journals (Sweden)

    Helmut Schlaad

    2011-02-01

    Full Text Available Poly(2-oxazolines are regarded as pseudopeptides, thus bioinspired polymers, due to their structural relationship to polypeptides. Materials and solution properties can be tuned by varying the side-chain (hydrophilic-hydrophobic, chiral, bioorganic, etc., opening the way to advanced stimulus-responsive materials and complex colloidal structures. The bioinspired “smart” solution and aggregation behavior of poly(2-oxazolines in aqueous environments are discussed in this review.

  7. New cyclodextrin derivative containing poly(L-lysine) dendrons for gene and drug co-delivery.

    Science.gov (United States)

    Ma, Dong; Zhang, Hong-Bin; Chen, Yu-Yun; Lin, Jian-Tao; Zhang, Li-Ming

    2013-09-01

    To develop a multifunctional polymeric carrier for gene and drug co-delivery, a new cyclodextrin derivative containing poly(L-lysine) dendrons was prepared by the click conjugation of per-6-azido-β-cyclodextrin with propargyl focal point poly(L-lysine) dendron of third generation and then characterized by FTIR, (1)H NMR, and GPC analyses. It was found that such a conjugate could form colloidally stable nanocomplexes with plasmid DNA in aqueous system and exhibited high gene transfection efficiency. Moreover, it could load efficiently methotrexate drug with anticancer activity and showed a sustained release behavior. Different from commonly used amphiphilic copolymers with cationic character, the as obtained cyclodextrin derivative may be used directly for the combinatorial delivery of nucleic acid and lipophilic anticancer drugs without a complicated micellization process. PMID:23769303

  8. Synthesis of Electroneutralized Amphiphilic Copolymers with Peptide Dendrons for Intramuscular Gene Delivery.

    Science.gov (United States)

    Pu, Linyu; Wang, Jiali; Li, Na; Chai, Qiuxia; Irache, Juan M; Wang, Gang; Tang, James Zhenggui; Gu, Zhongwei

    2016-06-01

    Intramuscular gene delivery materials are of great importance in plasmid-based gene therapy system, but there is limited information so far on how to design and synthesize them. A previous study showed that the peptide dendron-based triblock copolymer with its components arranged in a reversed biomembrane architecture could significantly increase intramuscular gene delivery and expression. Herein, we wonder whether copolymers with biomembrane-mimicking arrangement may have similar function on intramuscular gene delivery. Meanwhile, it is of great significance to uncover the influence of electric charge and molecular structure on the function of the copolymers. To address the issues, amphiphilic triblock copolymers arranged in hydrophilic-hydrophobic-hydrophilic structure were constructed despite the paradoxical characteristics and difficulties in synthesizing such hydrophilic but electroneutral molecules. The as-prepared two copolymers, dendronG2(l-lysine-OH)-poly propylene glycol2k(PPG2k)-dendronG2(l-lysine-OH) (rL2PL2) and dendronG3(l-lysine-OH)-PPG2k-dendronG3(l-lysine-OH) (rL3PL3), were in similar structure but had different hydrophilic components and surface charges, thus leading to different capabilities in gene delivery and expression in skeletal muscle. rL2PL2 was more efficient than Pluronic L64 and rL3PL3 when mediating luciferase, β-galactosidase, and fluorescent protein expressions. Furthermore, rL2PL2-mediated growth-hormone-releasing hormone expression could significantly induce mouse body weight increase in the first 21 days after injection. In addition, both rL2PL2 and rL3PL3 showed good in vivo biosafety in local and systemic administration. Altogether, rL2PL2-mediated gene expression in skeletal muscle exhibited applicable potential for gene therapy. The study revealed that the molecular structure and electric charge were critical factors governing the function of the copolymers for intramuscular gene delivery. It can be concluded that, combined

  9. Photochemical Isomerization and Topochemical Polymerization of the Programmed Asymmetric Amphiphiles

    Science.gov (United States)

    Kim, Dae-Yoon; Lee, Sang-A.; Jung, Daseal; Jeong, Kwang-Un

    2016-06-01

    For the advancement in multi-stimuli responsive optical devices, we report the elaborate molecular engineering of the dual photo-functionalized amphiphile (abbreviated as AZ1DA) containing both a photo-isomerizable azobenzene and a photo-polymerizable diacetylene. To achieve the efficient photochemical reactions in thin solid films, the self-assembly of AZ1DA molecules into the ordered phases should be precisely controlled and efficiently utilized. First, the remote-controllable light shutter is successfully demonstrated based on the reversible trans-cis photo-isomerization of azobenzene group in the smectic A mesophase. Second, the self-organized monoclinic crystal phase allows us to validate the photo-polymerization of diacetylene moiety for the photo-patterned thin films and the thermo-responsible color switches. From the demonstrations of optically tunable thin films, it is realized that the construction of strong relationships between chemical structures, molecular packing structures and physical properties of the programmed molecules is the core research for the development of smart and multifunctional soft materials.

  10. Tissue Regeneration through Self-Assembled Peptide Amphiphile Nanofibers

    Directory of Open Access Journals (Sweden)

    Hossein Hosseinkhani

    2006-01-01

    Full Text Available Introduction: In the present study, we hypothesized that a novelapproach to promote vascularization would be to create injectablethree dimensional (3-D scaffolds within growth factor that enhancethe sustained release of growth factor and induce the angiogenesis.Material and Methods: We demonstrate that a 3-D scaffold can beformed by mixing of peptide-amphiphile (PA aqueous solution withhepatocyte growth factor (HGF solution. PA was synthesized bystandard solid phase chemistry that ends with the alkylation of theNH2 terminus of the peptide. The sequence of arginine-glycineasparticacid (RGD was included in peptide design as well. A 3-Dnetwork of nanofibers was formed by mixing HGF suspensions withdilute aqueous solution of PA.Results: Scanning electron microscopy (SEM examination revealedthe formation of fibrous assemblies with an extremely high aspectratio and high surface areas with mean diameter of less than 200 nm.In vitro HGF release profile of 3-D nanofibers was investigated whileangiogenesis induced by the released HGF was being assessed. Invivo potential ability of PA nanofibers to induce angiogenesis wasassessed through subcutaneous injection of PA solution, HGFsolution, and PA in combination with HGF solutions. Injection of PAwith HGF induced significant angiogenesis around the injected site,in marked contrast to HGF injection alone and PA injection alone.Conclusion: The combination of HGF-induced angiogenesis is apromising procedure to improve tissue regeneration.

  11. Synthesis, aggregation, and chiroptical properties of chiral, amphiphilic dendrimers.

    Science.gov (United States)

    Laufersweiler, M J; Rohde, J M; Chaumette, J L; Sarazin, D; Parquette, J R

    2001-09-21

    The syntheses of amphiphilic dendrimers based on 3,5-dihydroxybenzyl alcohol containing tri- or tetrafunctional chiral central cores and allyl ester termini are described. Water solubility is imparted to the dendrimers via a palladium-catalyzed deprotection of the peripheral allyl esters. This method affords complete deprotection of the carboxylate surface because, in contrast to the basic hydrolysis of methyl ester termini, the solubility of partially hydrolyzed intermediates is maintained throughout the course of the deprotection, thereby avoiding precipitation during the reaction. Chiroptical analysis indicates that the structure of the dendrimers collapses in water, resulting in an increased steric effect upon the central core that is manifested by lower optical rotatory power. However, contributions to the chiroptical properties from the dendron branch segments were not evident in water or organic media, suggesting that chiral substructures were not developing in the branch segments of the dendrimers. Multiangle light scattering studies revealed that the dendrimers experienced significant aggregation in aqueous media that decreased at higher generations. This behavior could be rationalized by a change in conformational preference from a disklike conformation at low generations to a more globular conformation at higher generations. PMID:11559197

  12. Amphiphilic self-assembly of alkanols in protic ionic liquids.

    Science.gov (United States)

    Jiang, Haihui Joy; FitzGerald, Paul A; Dolan, Andrew; Atkin, Rob; Warr, Gregory G

    2014-08-21

    Strong cohesive forces in protic ionic liquids (PILs) can induce a liquid nanostructure consisting of segregated polar and apolar domains. Small-angle X-ray scattering has shown that these forces can also induce medium chain length n-alkanols to self-assemble into micelle- and microemulsion-like structures in ethylammonium (EA(+)) and propylammonium (PA(+)) PILs, in contrast to their immiscibility with both water and ethanolammonium (EtA(+)) PILs. These binary mixtures are structured on two distinct length scales: one associated with the self-assembled n-alkanol aggregates and the other with the underlying liquid nanostructure. This suggests that EA(+) and PA(+) enable n-alkanol aggregation by acting as cosurfactants, which EtA(+) cannot do because its terminating hydroxyl renders the cation nonamphiphilic. The primary determining factor for miscibility and self-assembly is the ratio of alkyl chain lengths of the alkanol and PIL cation, modulated by the anion type. These results show how ILs can support the self-assembly of nontraditional amphiphiles and enable the creation of new forms of soft matter. PMID:25068766

  13. Function of Amphiphilic Biomolecular Machines: Elastic Protein-based Polymers

    Science.gov (United States)

    Urry, Dan W.

    2000-03-01

    Elastic protein-based polymers function as biomolecular machines due to inverse temperature transitions of hydrophobic folding and assembly. The transitions occur either on raising the temperature from below to above the transition temperature, Tt, or on isothermally lowering Tt from above to below an operating temperature. The inverse temperature transition involves a decrease in entropy of the polymer component of the system on raising the temperature and a larger increase in solvent entropy on hydrophobic association. Tt depends on the quantity of hydrophobic hydration that undergoes transition to bulk water. Designed amphiphilic polymers perform free energy transductions involving the intensive variables of mechanical force, pressure, temperature, chemical potential, electrochemical potential and electromagnetic radiation and define a set of five axioms for their function as machines. The physical basis for these diverse energy conversions is competition for hydration between apolar (hydrophobic) and polar (e.g., charged) moieties. The effectiveness of these Tt-type entropic elastic protein-based machines is due to repeating peptide sequences that form regular, dynamic repeating structures and exhibit damping of backbone torsional oscillations on extension.

  14. Optimization of hypocrellin B derivative amphiphilicity and biological activity

    Institute of Scientific and Technical Information of China (English)

    LIU Xin; XIE Jie; ZHANG LuYong; CHEN HongXia; GU Ying; ZHAO JingQuan

    2009-01-01

    To satisfy the dual requirements of the fluent transportation in blood and the affinity to the target tissues of vascular diseases, hypocrellin derivatives with optimized amphiphilicity are expected. In this work, 3-amino-1-propanesulfonic acid and 4-amino-1-butanesulfonic acid substituted hypocrellin B,named compounds 1 and 2, were designed, synthesized in high yields and characterized. Besides greatly strengthened red absorption, the maximum solubility of compound 2 in phosphate buffered saline (PBS) is 4.2 mg/mL which is just enough to prepare an aqueous solution for intravenous injection in clinically acceptable concentration, while the partition coefficient between n-octanol and PBS,5.6, benefits the cell-uptake and biological activity as well. Furthermore, EPR measurements reveal that the photosensitization activities of the two compounds to generate semiquinone anion radicals, superoxide anion radicals and singlet oxygen are a little bit higher than those of taurine substituted hypocrellin B (THB), but the photodynamic activities to human lung cancer A549 cells are several times that of THB, mainly due to increases in lipophilicity and cell-uptake.

  15. Synthesis and Bioactivities of Kanamycin B-Derived Cationic Amphiphiles.

    Science.gov (United States)

    Fosso, Marina Y; Shrestha, Sanjib K; Green, Keith D; Garneau-Tsodikova, Sylvie

    2015-12-10

    Cationic amphiphiles derived from aminoglycosides (AGs) have been shown to exhibit enhanced antimicrobial activity. Through the attachment of hydrophobic residues such as linear alkyl chains on the AG backbone, interesting antibacterial and antifungal agents with a novel mechanism of action have been developed. Herein, we report the design and synthesis of seven kanamycin B (KANB) derivatives. Their antibacterial and antifungal activities, along with resistance/enzymatic, hemolytic, and cytotoxicity assays were also studied. Two of these compounds, with a C12 and C14 aliphatic chain attached at the 6″-position of KANB through a thioether linkage, exhibited good antibacterial and antifungal activity, were poorer substrates than KANB for several AG-modifying enzymes, and could delay the development of resistance in bacteria and fungi. Also, they were both relatively less hemolytic than the known membrane targeting antibiotic gramicidin and the known antifungal agent amphotericin B and were not toxic at their antifungal MIC values. Their oxidation to sulfones was also demonstrated to have no effect on their activities. Moreover, they both acted synergistically with posaconazole, an azole currently used in the treatment of human fungal infections. PMID:26592740

  16. Effect of Amphiphiles on the Rheology of Triglyceride Networks

    Science.gov (United States)

    Seth, Jyoti

    2014-11-01

    Networks of aggregated crystallites form the structural backbone of many products from the food, cosmetic and pharmaceutical industries. Such materials are generally formulated by cooling a saturated solution to yield the desired solid fraction. Crystal nucleation and growth followed by aggregation leads to formation of a space percolating fractal-network. It is understood that microstructural hierarchy and particle-particle interactions determine material behavior during processing, storage and use. In this talk, rheology of suspensions of triglycerides (TAG, like tristearin) will be explored. TAGs exhibit a rich assortment of polymorphs and form suspensions that are evidently sensitive to surface modifying additives like surfactants and polymers. Here, a theoretical framework will be presented for suspensions containing TAG crystals interacting via pairwise potentials. The work builds on existing models of fractal aggregates to understand microstructure and its correlation with material rheology. Effect of amphiphilic additives is derived through variation of particle-particle interactions. Theoretical predictions for storage modulus will be compared against experimental observations and data from the literature and micro structural predictions against microscopy. Such a theory may serve as a step towards predicting short and long-term behavior of aggregated suspensions formulated via crystallization.

  17. Polymer and Water Dynamics in Poly(vinyl alcohol/Poly(methacrylate Networks. A Molecular Dynamics Simulation and Incoherent Neutron Scattering Investigation

    Directory of Open Access Journals (Sweden)

    Ester Chiessi

    2011-10-01

    Full Text Available Chemically cross-linked polymer networks of poly(vinyl alcohol/poly(methacrylate form monolitic hydrogels and microgels suitable for biomedical applications, such as in situ tissue replacement and drug delivery. In this work, molecular dynamics (MD simulation and incoherent neutron scattering methods are used to study the local polymer dynamics and the polymer induced modification of water properties in poly(vinyl alcohol/poly(methacrylate hydrogels. This information is particularly relevant when the diffusion of metabolites and drugs is a requirement for the polymer microgel functionality. MD simulations of an atomic detailed model of the junction domain at the experimental hydration degree were carried out at 283, 293 and 313 K. The polymer-water interaction, the polymer connectivity and the water dynamics were investigated as a function of temperature. Simulation results are compared with findings of elastic and quasi-elastic incoherent neutron scattering measurements, experimental approaches which sample the same space-time window of MD simulations. This combined analysis shows a supercooled water component and an increase of hydrophilicity and mobility with temperature of these amphiphilic polymer networks.

  18. Self-assembly of ssDNA-amphiphiles into micelles, nanotapes and nanotubes

    Science.gov (United States)

    Pearce, Timothy R.

    The field of DNA nanotechnology utilizes DNA as a construction material to create functional supramolecular and multi-dimensional structures like two-dimensional periodic lattices and three-dimensional polyhedrons with order on the nanometer scale for many nanotechnology applications including molecular templating, nanosensors, and drug delivery. Single-stranded DNA (ssDNA) is often used to create these nanostructures as the DNA bases provide an intrinsic molecular code that can be exploited to allow for the programmed assembly of structures based upon Watson-Crick base-pairing. However, engineering these complex structures from biopolymers alone requires careful design to ensure that the intrinsic forces responsible for organizing the materials can produce the desired structures. Additional control over supramolecular assembly can be achieved by chemically modifying the ssDNA with hydrophobic moieties to create amphiphilic molecules, which adds the hydrophobic interaction to the list of contributing forces that drive the self-assembly process. We first explored the self-assembly behavior of a set of ssDNA aptamer-amphiphiles composed of the same hydrophobic tail and hydrophilic ssDNA aptamer headgroup but with different spacer molecules linking these groups together. Through the use of cryo-transmission electron microscopy (cryo-TEM), small angle x-ray scattering (SAXS), and circular dichroism (CD) we show that the aptamer-amphiphiles can assemble into a variety of structures depending on the spacer used. We demonstrated, for the first time, the creation of self-assembled aptamer-amphiphile nanotape structures and show that the choice of the spacer used in the design of aptamer-amphiphiles can influence their supramolecular self-assembly as well as the secondary structure of the aptamer headgroup. We next explored the role of the ssDNA headgroup on the amphiphile self-assembly behavior by designing amphiphiles with headgroups of multiple lengths and nucleotides

  19. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Purdy Drew, Kirstin R.; Sanders, Lori K.; Culumber, Zachary W.; Zribi, Olena; Wong, Gerard C.L.; (UIUC)

    2009-06-17

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers.

  20. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Drew, K.R.Purdy; Sanders, L.K.; Culumber, Z.W.; Zribi, O.; Wong, G.C.L.

    2009-05-21

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers.

  1. Cholesterol-Targeted Anticancer and Apoptotic Effects of Anionic and Polycationic Amphiphilic Cyclodextrin Nanoparticles.

    Science.gov (United States)

    Varan, Gamze; Öncül, Selin; Ercan, Ayşe; Benito, Juan M; Ortiz Mellet, Carmen; Bilensoy, Erem

    2016-10-01

    Amphiphilic cyclodextrins (CDs) are biocompatible derivatives of natural CDs and are able to form nanoparticles or polyplexes spontaneously. In this study, nanoparticles prepared from nonionic (6OCaproβCD) or cationic amphiphilic CD (PC βCDC6) were used comparatively to develop nanoparticles intended for breast cancer therapy. The characterization of these nanoparticles was performed both by in vitro and cell culture studies. Furthermore, the apoptotic and cytotoxic effects of blank amphiphilic CDs were demonstrated by various mechanistic methods including Caspase-8 activity, lipid peroxidation assay, TUNEL assay, Tali(®)-based image analysis, cholesterol assay, and gene expression studies. Blank nanoparticles exerted cytotoxicity against a variety of cancer cells (MCF-7, HeLa, HepG2, and MB49) but none to healthy cells (L929, G/G). Interestingly, blank 6OCaproβCD and blank PC βCDC6 derivatives were found to be intrinsically effective on cell number and membrane integrity of MCF-7 cells in apoptosis studies. Further in-depth studies were performed to elucidate the selective mechanism of anticancer action in MCF-7 cells caused by these amphiphilic CDs. In conclusion, blank amphiphilic CD nanoparticles induced apoptosis through mitochondrial pathway targeted to cholesterol microdomains in cancer cell membrane. PMID:27488900

  2. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    International Nuclear Information System (INIS)

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers

  3. Fluorinated amphiphiles control the insertion of α-hemolysin pores into lipid bilayers.

    Science.gov (United States)

    Raychaudhuri, Pinky; Li, Qiuhong; Mason, Amy; Mikhailova, Ellina; Heron, Andrew J; Bayley, Hagan

    2011-03-15

    The insertion of fully folded and assembled ion channels and pores into planar lipid bilayers for electrical recording has been facilitated by the use of conventional detergents at a final concentration below the critical micelle concentration (CMC). After the desired number of channels or pores (often one) has been incorporated into a bilayer, it is important to prevent further insertion events, which is often done by awkward techniques such as perfusion. Here, we show that the addition of single-chain fluorinated amphiphiles (F-amphiphiles) with zwitterionic, simple neutral, and neutral oligomeric headgroups at a concentration above the CMC prevents the further insertion of staphylococcal α-hemolysin pores, MspA pores, and Kcv potassium channels into lipid bilayers. We found the commercially available F(6)FC (fluorinated fos-choline with a C(6)F(13)C(2)H(4) chain) to be the least perturbing and most effective agent for this purpose. Bilayers are known to be resistant to F-amphiphiles, which in this case we suppose sequester the pores and channels within amphiphile aggregates. We suggest that F-amphiphiles might be useful in the fabrication of bilayer arrays for nanopore sensor devices and the rapid screening of membrane proteins. PMID:21275394

  4. SYNTHESIS OF AN AMPHIPHILIC PPESK-g-P(PEGMA) GRAFT COPOLYMER VIA ATRP AND ITS USE IN BLEND MODIFICATION OF PPESK MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    Han-bang Dong; You-yi Xu; Zhuan Yi

    2009-01-01

    Preparation of an amphiphilic graft copolymer having poly(phthalazinone ether sulfone ketone) (PPESK) as main chains was carried out by atom transfer radical polymerization (ATRP). The precursor, chloromethylated PPESK (CMPPESK), was prepared by using chloromethylether as chloromethylation agent. Then, poly(ethylene glycol) methyl ether methacrylate (PEGMA) was used as monomer to synthesize PPESK-g-P(PEGMA) by ATRP method under the catalysis of a cuprous chloride/2,2’-bipyridyl system. PPESK/PPESK-g-P(PEGMA) blend membranes were prepared and characterized. Chemical structures of the products were confirmed by FT-IR spectroscopy and ~1H-NMR analysis. The thermal properties of PPESK-g-P(PEGMA) were analyzed by thermal gravity analysis (TGA). XPS method was used to analyze the composition of the blend membrane. FESEM was employed to investigate the morphology of the membranes. The hydrophilicity of blend membranes was measured by water contact angle test. It turns out that the hydrophilicity and surface wettability were enhanced after modification. However, the thermal properties were negatively affected.

  5. Amphiphilic block copolymers bearing six-membered ortho ester ring in side chains as potential drug carriers: synthesis, characterization, and in vivo toxicity evaluation.

    Science.gov (United States)

    Luo, Shi; Tao, Yangyang; Tang, Rupei; Wang, Rui; Ji, Weihang; Wang, Chun; Zhao, Youliang

    2014-07-01

    A new type of amphiphilic block copolymers, poly(ethylene glycol)-block-poly(2-methyl-acrylicacid 2-methoxy-5-methyl-[1,3]dioxin-5-ylmethyl ester) (PEG-b-PMME), bearing acid-labile six-membered ortho ester rings in side chains was synthesized by reversible addition-fragmentation chain-transfer polymerization, and the influence of chain length of the hydrophobic PMME block on micelle properties was investigated. The PEG-b-PMME micelles were stable in aqueous buffer at physiological pH with a low critical micelle concentration. Nile Red as a model drug was encapsulated into the micelles to explore the release profiles. The Nile Red-loaded polymeric micelles showed rapid release of Nile Red in weakly acidic environments (pH 5) but slow release under physiological condition (pH 7.4), due to different hydrolysis rate of ortho ester side chains of PEG-b-PMME. The Paclitaxel (PTX)-loaded micelles retained potency in killing lung cancer cells (A549), compared with the free PTX. No obvious toxicity was found in vitro and in vivo after intraperitoneal injection of the micelles, which confirms that the PEG-b-PMME micelles with unique acid-labile characteristic have great potential as nano-scaled carriers for drug delivery.

  6. Well-organized meso-macroporous TiO2/SiO2 film derived from amphiphilic rubbery comb copolymer.

    Science.gov (United States)

    Jeon, Harim; Lee, Chang Soo; Patel, Rajkumar; Kim, Jong Hak

    2015-04-15

    We report the facile synthesis of a well-organized meso-macroporous TiO2/SiO2 thin film with high porosity and good interconnectivity from a binary mixture (i.e., titania precursor and polymer template). Our process is based on self-assembly of the amphiphilic rubbery comb copolymer, poly(dimethylsiloxane)-g-poly(oxyethylene methacrylate) (PDMS-g-POEM) with titanium tetraisopropoxide (TTIP). SiO2 is self-provided by thermal oxidation of PDMS chains during calcination under air. The selective, preferential interaction between TTIP and the hydrophilic POEM chains was responsible for the formation of well-organized TiO2/SiO2 films, as supported by transmission electron microscopy, scanning electron microscopy, X-ray photospectroscopy, and X-ray diffraction analyses. We investigated in detail the effect of precursor content, solvent type, and polymer concentration on thin film morphology. Photodegradation of methyl orange by the well-organized meso-macroporous TiO2/SiO2 film was greater than that of a dense TiO2 film prepared without PDMS-g-POEM as well as a SiO2-etched TiO2 film. These results indicate that the well-organized structure and SiO2 doping of the TiO2 film play a pivotal role in enhancing its photocatalytic properties. PMID:25805232

  7. Multiple H-bonds directed self-assembly of an amphiphilic and plate-like codendrimer with janus faces at water-air interface.

    Science.gov (United States)

    Yang, Miao; Wang, Wei; Lieberwirth, Ingo; Wegner, Gerhard

    2009-05-01

    An amphiphilic diblock codendrimer composed of a third generation poly(methallyl dichloride) end-capped by eight hydroxyl groups (PMDC(OH)(8)) and a second generation poly(urethane amide) end-capped by four alkyl groups (PUA(C16)(4)) were found to self-assemble into highly oriented ribbons at the water-air interface. Further investigation on the ribbon formation shows that the ribbons are hierarchically self-organized by the janus and plate-like shape of g3-PMDC(OH)(8)-b-g2-PUA(C16)(4). Sextuple H-bonds existing at different positions of the molecular plate are the main driving force for the one-dimensional growth of the ribbon. The recognition of these H-bonds leads to a highly ordered stacking of the codendrimers, and the crystallization of the alkyl chains results in a primary ribbon with a ca. 7.6 +/- 0.5 nm width. The primary ribbons prefer to organize into secondary ribbons with an average width of 53 +/- 6.0 nm. The manner of recognition and assembly is similar to the organization of a kind of toy building block with janus faces, which provides a new strategy to the design of well-defined nanomaterials. PMID:19361164

  8. Complex self-assembly of reverse poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) triblock copolymers with long hydrophobic and extremely lengthy hydrophilic blocks.

    Science.gov (United States)

    Cambón, Adriana; Figueroa-Ochoa, Edgar; Juárez, Josué; Villar-Álvarez, Eva; Pardo, Alberto; Barbosa, Silvia; Soltero, J F Armando; Taboada, Pablo; Mosquera, Víctor

    2014-05-15

    Amphiphilic block copolymers have emerged during last years as a fascinating substrate material to develop micellar nanocontainers able to solubilize, protect, transport, and release under external or internal stimuli different classes of cargos to diseased cells or tissues. However, this class of materials can also induce biologically relevant actions, which complement the therapeutic activity of their cargo molecules through their mutual interactions with biologically relevant entities (cellular membranes, proteins, organelles...); these interactions at the same time, are regulated by the nature, conformation, and state of the copolymeric chains. For these reasons, in this paper we investigated the self-assembly process and physico-chemcial properties of two reverse triblock poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers, BO14EO378BO14 and BO21EO385BO21, which have been recently found to be very useful as drug delivery nanovehicles and biological response modifiers under certain conditions (A. Cambón et al. Int. J. Pharm. 2013, 445, 47-57) in order to obtain a clear picture of the solution behavior of this class or block copolymers and to understand their biological activity. These block copolymers are characterized by possessing long BO blocks and extremely lengthy central EO ones, which provide them with a rich rheological behavior characterized by the formation of flowerlike micelles with sizes ranging from 20 to 40 nm in aqueous solution and the presence of intermicellar bridging even at low copolymers concentrations as denoted by atomic force microscopy. Bridging is also clearly observed by analyzing the rheological response of these block copolymers both storage and loss moduli upon changes on time, temperature, and or concentration. Strikingly, the relatively wide Poisson distribution of the polymeric chains make the present copolymers behave rather distinctly to conventional associative thickeners. The observed rich

  9. Self-Assembly in a Mixture of Two Poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) Copolymers in Water

    Science.gov (United States)

    Zhou; Alexandridis; Khan

    1996-11-10

    The self-assembly behavior in water of a mixture of two poly (ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymers, (EO)13(PO)30(EO)13 (L64) and (EO)37(PO)58(EO)37 (P105), was explored at 25°C. The phase boundaries were established using 2H-NMR and inspection under polarized light; the structure of the various lyotropic liquid crystalline (LLC) phases was determined with small-angle X-ray scattering, while viscosity and differential scanning calorimetry measurements were used to probe the isotropic water-rich solution region. Isotropic regions, similar to the neat polymers, are stable at high polymer content. The addition of water induces structure in the amphiphilic block copolymer system. An extended lamellar (D) LLC phase is formed at 20-25% water content; a hexagonal (E) and a cubic (I) LLC phases supersede D at higher water contents. In addition to the above, a narrow isotropic region (L') is observed on the L64-water binary axis, in equilibrium with the E and the D phases. The hexagonal and lamellar LLC phases extended all the way from the L64-rich to the P105-rich side of the ternary L64-P105-water phase diagram; the characteristic hexagonal and lamellar structural dimensions varied linearly with P105 content in the L64-P105 mixture at a constant water concentration. An isotropic (micellar) solution phase (L1) dominates the high-water content corner of the ternary phase diagram. Viscosity measurements in this region provided evidence for increased interactions between the micelles as the boundary to the LLC phases was approached. PMID:8954676

  10. pH-Responsive Poly(ethylene glycol)/Poly(L-lactide) Supramolecular Micelles Based on Host-Guest Interaction.

    Science.gov (United States)

    Zhang, Zhe; Lv, Qiang; Gao, Xiaoye; Chen, Li; Cao, Yue; Yu, Shuangjiang; He, Chaoliang; Chen, Xuesi

    2015-04-29

    pH-responsive supramolecular amphiphilic micelles based on benzimidazole-terminated poly(ethylene glycol) (PEG-BM) and β-cyclodextrin-modified poly(L-lactide) (CD-PLLA) were developed by exploiting the host-guest interaction between benzimidazole (BM) and β-cyclodextrin (β-CD). The dissociation of the supramolecular micelles was triggered in acidic environments. An antineoplastic drug, doxorubicin (DOX), was loaded into the supramolecular micelles as a model drug. The release of DOX from the supramolecular micelles was clearly accelerated as the pH was reduced from 7.4 to 5.5. The DOX-loaded PEG-BM/CD-PLLA supramolecular micelles displayed an enhanced intracellular drug-release rate in HepG2 cells compared to the pH-insensitive DOX-loaded PEG-b-PLLA counterpart. After intravenous injection into nude mice bearing HepG2 xenografts by the tail vein, the DOX-loaded supramolecular micelles exhibited significantly higher tumor inhibition efficacy and reduced systemic toxicity compared to free DOX. Furthermore, the DOX-loaded supramolecular micelles showed a blood clearance rate markedly lower than that of free DOX and comparable to that of the DOX-loaded PEG-b-PLLA micelles after intravenous injection into rats. Therefore, the pH-responsive PEG-BM/CD-PLLA supramolecular micelles hold potential as a smart nanocarrier for anticancer drug delivery. PMID:25856564

  11. Tuning peptide amphiphile supramolecular structure for biomedical applications

    Science.gov (United States)

    Pashuck, Eugene Thomas, III

    The use of biomaterials in regenerative medicine has been an active area of research for more than a decade. Peptide amphiphiles, which are short peptide sequences coupled to alkyl tails, have been studied in the Stupp group since the beginning of the decade and been used for a variety of biomedical applications. Most of the work has focused on the bioactive epitopes places on the periphery of the PA molecules, but the interior amino acids, known as the beta-sheet region, give the PA nanofiber gel much of its mechanical strength. To study the important parameters in the beta-sheet region, six PA molecules were constructed to determine the influence of beta-sheet length and order of the amino acids in the beta-sheet. It was found that having beta-sheet forming amino acids near the center of the fiber improves PA gel stiffness, and that having extra amino acids that have preferences for other secondary structures, like alpha-helix decreased the gels stiffness. Using FTIR and circular dichroism it was found that the mechanical properties are influenced by the amount of twist in the beta-sheet, and PAs that have more twisted beta-sheets form weaker gels. The effect amino acid properties have on peptide amphiphile self-assembly where studied by synthesizining molecules with varying side group size and hydrophobicity. It was found that smaller amino acids lead to stiffer gels and when two amino acids had the same size the amino acid with the larger beta-sheet propensity lead to a stiffer gel. Furthermore, small changes in peptide structure were found to lead to big changes in nanostructure, as leucine and isoleucine, which have the same size but slightly different structures, form flat ribbons and cylindrical nanofibers, respectively. Phenylalanine and alanine were studied more indepth because they represent the effects of adding an aromatic group to amino acids in the beta-sheet regon. These phenylalanine PAs formed short, twisted ribbons when freshly dissolved in water

  12. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    Giuseppina Raffaini

    2015-12-01

    Full Text Available Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a “bottom up” approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD, which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties.

  13. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations.

    Science.gov (United States)

    Raffaini, Giuseppina; Mazzaglia, Antonino; Ganazzoli, Fabio

    2015-01-01

    Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a "bottom up" approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD), which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties. PMID:26734094

  14. Biomimetic Self-Templated Hierarchical Structures of Collagen-Like Peptide Amphiphiles.

    Science.gov (United States)

    Jin, Hyo-Eon; Jang, Jaein; Chung, Jinhyo; Lee, Hee Jung; Wang, Eddie; Lee, Seung-Wuk; Chung, Woo-Jae

    2015-10-14

    Developing hierarchically structured biomaterials with tunable chemical and physical properties like those found in nature is critically important to regenerative medicine and studies on tissue morphogenesis. Despite advances in materials synthesis and assembly processes, our ability to control hierarchical assembly using fibrillar biomolecules remains limited. Here, we developed a bioinspired approach to create collagen-like materials through directed evolutionary screening and directed self-assembly. We first synthesized peptide amphiphiles by coupling phage display-identified collagen-like peptides to long-chain fatty acids. We then assembled the amphiphiles into diverse, hierarchically organized, nanofibrous structures using directed self-assembly based on liquid crystal flow and its controlled deposition. The resulting structures sustained and directed the growth of bone cells and hydroxyapatite biominerals. We believe these self-assembling collagen-like amphiphiles could prove useful in the structural design of tissue regenerating materials. PMID:26392232

  15. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

    Science.gov (United States)

    Mazzaglia, Antonino; Ganazzoli, Fabio

    2015-01-01

    Summary Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a “bottom up” approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD), which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties. PMID:26734094

  16. High Selective Performance of Designed Antibacterial and Anticancer Peptide Amphiphiles.

    Science.gov (United States)

    Chen, Cuixia; Chen, Yucan; Yang, Cheng; Zeng, Ping; Xu, Hai; Pan, Fang; Lu, Jian Ren

    2015-08-12

    Short designed peptide amphiphiles are attractive at killing bacteria and inhibiting cancer cell growth, and the flexibility in their structural design offers a great potential for improving their potency and biocompatibility to mammalian host cells. Amino acid sequences such as G(IIKK)nI-NH2 (n≥3) have been shown to be membrane lytic, but terminal amino acid modifications could impose a huge influence on their performance. We report in this work how terminal amino acid modifications to G(IIKK)3I-NH2 influence its α-helical structure, membrane penetrating ability, and selective actions against different cell types. Deletion of an N-terminal Gly or a C-terminal Ile did not affect their antibacterial activity much, an observation consistent with their binding behavior to negatively charged membrane lipid monolayers. However, the cytotoxicity against mammalian cells was much worsened by the N-terminal Gly deletion, consistent with an increase in its helical content. Despite little impact on the antibacterial activity of G(IIKK)3I-NH2, deletion of both terminal amino acids greatly reduced its antitumor activity. Cholesterol present in tumor cell membrane-mimic was thought to constrain (IIKK)3-NH2 from penetrating into the cancerous membranes, evident from its lowest surface physical activity at penetrating model lipid membranes. On the other hand, its low toxicity to normal mammalian cells and high antibacterial activity in vitro and in vivo made it an attractive antibacterial agent. Thus, terminal modifications can help rebalance the different interactions involved and are highly effective at manipulating their selective membrane responses.

  17. Colloidosomes formed by nonpolar/polar/nonpolar nanoball amphiphiles

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hung-Yu; Sheng, Yu-Jane, E-mail: yjsheng@ntu.edu.tw, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan (China); Tu, Sheng-Hung [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan (China); Tsao, Heng-Kwong, E-mail: yjsheng@ntu.edu.tw, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical and Materials Engineering and Department of Physics, National Central University, Jhongli 320, Taiwan (China)

    2014-08-07

    Fullerene-based amphiphiles are able to form bilayer vesicles in aqueous solution. In this study, the self-assembly behavior of polymer-tethered nanoballs (NBs) with nonpolar/polar/nonpolar (n-p-n{sup ′}) motif in a selective solvent is investigated by dissipative particle dynamics. A model NB bears two hydrophobic polymeric arms (n{sup ′}-part) tethered on an extremely hydrophobic NB (n-part) with hydrophilic patch (p-part) patterned on its surface. Dependent on the hydrophobicity and length of tethered arms, three types of aggregates are exhibited, including NB vesicle, core-shell micelle, and segmented-worm. NB vesicles are developed for a wide range of hydrophobic arm lengths. The presence of tethered arms perturbs the bilayer structure formed by NBs. The structural properties including the order parameter, membrane thickness, and area density of the inner leaflet decrease with increasing the arm length. These results indicate that for NBs with longer arms, the extent of interdigitation in the membrane rises so that the overcrowded arms in the inner corona are relaxed. The transport and mechanical properties are evaluated as well. As the arm length grows, the permeability increases significantly because the steric bulk of tethered arms loosens the packing of NBs. By contrast, the membrane tension decreases owing to the reduction of NB/solvent contacts by the polymer corona. Although fusion can reduce membrane tension, NB vesicles show strong resistance to fusion. Moreover, the size-dependent behavior observed in small liposomes is not significant for NB vesicles due to isotropic geometry of NB. Our simulation results are consistent with the experimental findings.

  18. Colloidosomes formed by nonpolar/polar/nonpolar nanoball amphiphiles.

    Science.gov (United States)

    Chang, Hung-Yu; Tu, Sheng-Hung; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2014-08-01

    Fullerene-based amphiphiles are able to form bilayer vesicles in aqueous solution. In this study, the self-assembly behavior of polymer-tethered nanoballs (NBs) with nonpolar/polar/nonpolar (n-p-n') motif in a selective solvent is investigated by dissipative particle dynamics. A model NB bears two hydrophobic polymeric arms (n'-part) tethered on an extremely hydrophobic NB (n-part) with hydrophilic patch (p-part) patterned on its surface. Dependent on the hydrophobicity and length of tethered arms, three types of aggregates are exhibited, including NB vesicle, core-shell micelle, and segmented-worm. NB vesicles are developed for a wide range of hydrophobic arm lengths. The presence of tethered arms perturbs the bilayer structure formed by NBs. The structural properties including the order parameter, membrane thickness, and area density of the inner leaflet decrease with increasing the arm length. These results indicate that for NBs with longer arms, the extent of interdigitation in the membrane rises so that the overcrowded arms in the inner corona are relaxed. The transport and mechanical properties are evaluated as well. As the arm length grows, the permeability increases significantly because the steric bulk of tethered arms loosens the packing of NBs. By contrast, the membrane tension decreases owing to the reduction of NB/solvent contacts by the polymer corona. Although fusion can reduce membrane tension, NB vesicles show strong resistance to fusion. Moreover, the size-dependent behavior observed in small liposomes is not significant for NB vesicles due to isotropic geometry of NB. Our simulation results are consistent with the experimental findings.

  19. Controlled synthesis of novel 3D dendritic Bi2S3 /cross-linked poly(vinyl alcohol) nanocomposites

    International Nuclear Information System (INIS)

    Novel spherical three-dimensional (3D) dendritic Bi2S3 /cross-linked poly(vinyl alcohol) (PVA) nanocomposites were successfully synthesized in aqueous solution of amphiphilic polyvinylacetone (PVKA) (ketalization degree DH = 0.549), via one-step in situ decomposition of the complex [Bi(Tu)x]3+ under γ-ray irradiation, utilizing the controllable hydrolysis property of PVKA in acidic solution. Herein, PVA chains are obtained from the hydrolysed PVKA. These uniform 3D spherical nanocomposites have a structure similar to that found in the natural lotus leaf, where every microscale papilla on the leaf surface is covered by nanoscale papillae

  20. Self-assembly mechanisms of nanofibers from peptide amphiphiles in solution and on substrate surfaces

    Science.gov (United States)

    Liao, Hsien-Shun; Lin, Jing; Liu, Yang; Huang, Peng; Jin, Albert; Chen, Xiaoyuan

    2016-08-01

    We report the investigation of the self-assembly mechanism of nanofibers, using a small peptide amphiphile (NapFFKYp) as a model. Combining experimental and simulation methods, we identify the self-assembly pathways in the solution and on the substrates, respectively. In the solution, peptide amphiphiles undergo the nucleation process to grow into nanofibers. The nanofibers can further twist into high-ordered nanofibers with aging. On the substrates, peptide amphiphiles form nanofibers and nanosheet structures simultaneously. This surface-induced nanosheet consists of rod-like structures, and its thickness is substrate-dependent. Most intriguingly, water can transform the nanosheet into the nanofiber. Molecular dynamic simulation suggests that hydrophobic and ion-ion interactions are dominant forces during the self-assembly process.We report the investigation of the self-assembly mechanism of nanofibers, using a small peptide amphiphile (NapFFKYp) as a model. Combining experimental and simulation methods, we identify the self-assembly pathways in the solution and on the substrates, respectively. In the solution, peptide amphiphiles undergo the nucleation process to grow into nanofibers. The nanofibers can further twist into high-ordered nanofibers with aging. On the substrates, peptide amphiphiles form nanofibers and nanosheet structures simultaneously. This surface-induced nanosheet consists of rod-like structures, and its thickness is substrate-dependent. Most intriguingly, water can transform the nanosheet into the nanofiber. Molecular dynamic simulation suggests that hydrophobic and ion-ion interactions are dominant forces during the self-assembly process. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr04672j

  1. Sacrificial amphiphiles: Eco-friendly chemical herders as oil spill mitigation chemicals.

    Science.gov (United States)

    Gupta, Deeksha; Sarker, Bivas; Thadikaran, Keith; John, Vijay; Maldarelli, Charles; John, George

    2015-06-01

    Crude oil spills are a major threat to marine biota and the environment. When light crude oil spills on water, it forms a thin layer that is difficult to clean by any methods of oil spill response. Under these circumstances, a special type of amphiphile termed as "chemical herder" is sprayed onto the water surrounding the spilled oil. The amphiphile forms a monomolecular layer on the water surface, reducing the air-sea surface tension and causing the oil slick to retract into a thick mass that can be burnt in situ. The current best-known chemical herders are chemically stable and nonbiodegradable, and hence remain in the marine ecosystem for years. We architect an eco-friendly, sacrificial, and effective green herder derived from the plant-based small-molecule phytol, which is abundant in the marine environment, as an alternative to the current chemical herders. Phytol consists of a regularly branched chain of isoprene units that form the hydrophobe of the amphiphile; the chain is esterified to cationic groups to form the polar group. The ester linkage is proximal to an allyl bond in phytol, which facilitates the hydrolysis of the amphiphile after adsorption to the sea surface into the phytol hydrophobic tail, which along with the unhydrolyzed herder, remains on the surface to maintain herding action, and the cationic group, which dissolves into the water column. Eventual degradation of the phytol tail and dilution of the cation make these sacrificial amphiphiles eco-friendly. The herding behavior of phytol-based amphiphiles is evaluated as a function of time, temperature, and water salinity to examine their versatility under different conditions, ranging from ice-cold water to hot water. The green chemical herder retracted oil slicks by up to ~500, 700, and 2500% at 5°, 20°, and 35°C, respectively, during the first 10 min of the experiment, which is on a par with the current best chemical herders in practice. PMID:26601197

  2. Polyplex Micelles with Double-Protective Compartments of Hydrophilic Shell and Thermoswitchable Palisade of Poly(oxazoline)-Based Block Copolymers for Promoted Gene Transfection.

    Science.gov (United States)

    Osawa, Shigehito; Osada, Kensuke; Hiki, Shigehiro; Dirisala, Anjaneyulu; Ishii, Takehiko; Kataoka, Kazunori

    2016-01-11

    Improving the stability of polyplex micelles under physiological conditions is a critical issue for promoting gene transfection efficiencies. To this end, hydrophobic palisade was installed between the inner core of packaged plasmid DNA (pDNA) and the hydrophilic shell of polyplex micelles using a triblock copolymer consisting of hydrophilic poly(2-ethyl-2-oxazoline), thermoswitchable amphiphilic poly(2-n-propyl-2-oxazoline) (PnPrOx) and cationic poly(L-lysine). The two-step preparation procedure, mixing the triblock copolymer with pDNA below the lower critical solution temperature (LCST) of PnPrOx, followed by incubation above the LCST to form a hydrophobic palisade of the collapsed PnPrOx segment, induced the formation of spatially aligned hydrophilic-hydrophobic double-protected polyplex micelles. The prepared polyplex micelles exhibited significant tolerance against attacks from nuclease and polyanions compared to those without hydrophobic palisades, thereby promoting gene transfection. These results corroborated the utility of amphiphilic poly(oxazoline) as a molecular thermal switch to improve the stability of polyplex gene carriers relevant for physiological applications. PMID:26682466

  3. Fusiogenic activity of natural amphiphiles, 5-n-alkylresorcinols in a yeast protoplast system.

    Science.gov (United States)

    Kozubek, A; Skała, J

    1995-01-01

    Two homologues of cereal grain resorcinolic lipids, 5-n-heptadecylresorcinol and 5-n-heptadecenylresorcinol studied in the system employing yeast cell protoplasts showed marked fusiogenic activity. The frequency of hybrid formation induced by studied amphiphiles was significantly higher than that obtained with the use of 40% (w/v) polyethylene glycol 4000. The resorcinolic lipids as fusion-inducing agents did not affect regeneration of the cellular wall. The fusiogenic activity of resorcinolic lipids lost when calcium ions were absent in the medium. Fusiogenic activity of studied amphiphiles is related to their ability to induce non-bilayer structures within the cellular membranes. PMID:8579682

  4. Monte Carlo simulation for the micellar behavior of amphiphilic comb-like copolymers

    Institute of Scientific and Technical Information of China (English)

    冯莺; 隋家贤; 赵季若; 陈欣方

    2000-01-01

    Micellar behaviors in 2D and 3D lattice models for amphiphilic comb-like copolymers in water phase and in water/oil mixtures were simulated. A dynamical algorithm together with chain reptation movements was used in the simulation. Three-dimension displaying program was pro-grammed and free energy was estimated by Monte Carlo technigue. The results demonstrate that reduced interaction energy influences morphological structures of micelle and emulsion ??stems greatly; 3D simulation showing can display more direct images of morphological structures; the amphiphilic comb-like polymers with a hydrophobic main chain and hydrophilic side chains have lower energy in water than in oil.

  5. Synthesis of amphiphilic aminated inulin via 'click chemistry' and evaluation for its antibacterial activity.

    Science.gov (United States)

    Dong, Fang; Zhang, Jun; Yu, Chunwei; Li, Qing; Ren, Jianming; Wang, Gang; Gu, Guodong; Guo, Zhanyong

    2014-09-15

    Inulins are a group of abundant, water-soluble, renewable polysaccharides, which exhibit attractive bioactivities and natural properties. Improvement such as chemical modification of inulin is often performed prior to further utilization. We hereby presented a method to modify inulin at its primary hydroxyls to synthesize amphiphilic aminated inulin via 'click chemistry' to facilitate its chemical manipulation. Additionally, its antibacterial property against Staphylococcus aureus (S. aureus) was also evaluated and the best inhibitory index against S. aureus was 58% at 1mg/mL. As the amphiphilic aminated inulin is easy to prepare and exhibits improved bioactivity, this material may represent as an attractive new platform for chemical modifications of inulin.

  6. Intra-chain organisation of hydrophobic residues controls inter-chain aggregation rates of amphiphilic polymers

    CERN Document Server

    Varilly, Patrick; Kirkegaard, Julius B; Knowles, Tuomas P J; Chandler, David

    2016-01-01

    Aggregation of amphiphiles through the action of hydrophobic interactions is a common feature in soft condensed matter systems and is of particular importance in the context of biophysics as it underlies both the generation of functional biological machinery as well as the formation of pathological misassembled states of proteins. Here we explore the aggregation behaviour of amphiphilic polymers using lattice Monte-Carlo calculations and show that the distribution of hydrophobic residues within the polymer sequence determines the facility with which dry/wet interfaces can be created and that such interfaces drive the aggregation process.

  7. 两亲性脂肪族聚氨酯的合成与表征%Svnthesis and Characterization of Amphiphilic Aliphatic Polyurethane

    Institute of Scientific and Technical Information of China (English)

    张立柱; 赵辉鹏; 张高奇; 查刘生

    2011-01-01

    A series of amphiphilic aliphatic polyurethanes with different molecular weights from 10000 to 50000 were synthesized using isophorone diisocyanate as polyisocyanates poly (ethylene glycol) of molecular weight 6000 as polyol, and cetyl alcohol as end capping reagent. Their structure and the rheological property of their aqueous dispersion were characterized by fourier transformation infrared spectroscopy( FT-IR), proton nuclear magnetic resonance(1 H-NMR), gel permeation chromatography-light scattering( GPC-LS), and advanced rotational rheometer.The results showed that the number-averaged molecular weights and end capping ratios of amphiphilic aliphatic polyurethanes could be obtained by the integral area of related 1 H-NMR peaks, and their number-averaged molecular weight were nearly consistent with the results measured by GPC-LS and the theoretical values. At the same concentration, as the hydrophobic block contents of the amphiphilic aliphatic polyurethanes increased, the zero shear viscosity was enhanced and the onset concentration of shear thinning was decreased.%采用异佛尔酮二异氰酸酯和相对分子质量为6000的聚乙二醇为原料、十六醇为封端剂,合成了相对分子质量在10000~50000范围内的一系列两亲性脂肪族聚氨酯.用傅立叶变换红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、凝胶渗透色谱-光散射联用仪(GPC-LS)、高级旋转流变仪对两亲性聚氨酯的结构及其水分散液的流变性能进行了研究.结果表明,用1H-NMR谱图中相关峰的面积通过计算得到两亲性脂肪族聚氨酯的数均相对分子质量和疏水链段的封端率,数均相对分子质量大小与GPC-LS测得的结果以及理论值基本一致.在相同浓度情况下,随着两亲性聚氨酯分子链中疏水链段含量的增加,其水分散液的零剪切粘度增大,开始出现剪切变稀的剪切速率减小.

  8. Preparation of hydrophilic poly(lactic acid) tissue engineering scaffold via (PLA)-(PLA-b-PEG)-(PEG) solution casting and thermal-induced surface structural transformation.

    Science.gov (United States)

    Zhu, Xiaomin; Zhong, Tian; Huang, Ran; Wan, Ajun

    2015-01-01

    Porous poly(lactic acid) (PLA) tissue engineering scaffolds with a hydrophilic surface assembled by polyethylene glycol aggregations were prepared by the solvent casting/particulate leaching method from (PLA)-(PLA-b-PEG)-(PEG) blend solution, where the PLA-b-PEG block polymer serves as an amphiphilic glue between two phases. A thermal recrystallization process was inserted before leaching to induce a phase separation, which subsequently squeezes out PEG to form a hydrophilic shell. Characterizations of XRD and DSC indicated the composition and mixing states of materials. The water contact angle test qualitatively presented the excellent hydrophilicity compared to the pure PLA or PLA-PEG simple blend scaffold. The scanning electron microscope results confirmed the formation of porous structure of [Formula: see text] pore size, with an observable phase separation on the surface. The scaffold was degraded in PBS at [Formula: see text], and the degradation exhibits a three-stage behavior, which evidenced the amphiphilically glued phase separations.

  9. Self-assembling peptide amphiphile nanostructures for cancer therapy

    Science.gov (United States)

    Soukasene, Stephen

    The application of nanotechnology to cancer therapy shows great promise for reducing the burden of the disease. By virtue of their size, nanoscale objects preferentially accumulate in tumor tissue through an enhanced permeability and retention (EPR) effect. However, to fully overcome the issues that limit current cancer treatments, viable nanostructures must also impart multifunctionality and be fully compatible with their biological surrounds. The self-assembling peptide amphiphile (PA) materials studied extensively in the Stupp Research Group form very biocompatible high aspect ratio nanostructures that meet these criteria. This thesis investigates the development of PA nanostructures designed to treat cancer. We first look to use the PA as a drug delivery vehicle by entrapping a small hydrophobic anti-cancer drug, camptothecin, in the core of the nanostructures. Using a solvent evaporation technique to load the drug into the PA nanofibers, we are able to improve the aqueous solubility of the molecule by nearly 30-fold. TEM and AFM studies show that entrapment of drug molecules does not disrupt the self-assembled morphology of the nanofiber. In vitro and in vivo studies are also conducted to demonstrate the bioactivity of the drug after its entrapment. As a potential platform for novel therapeutics, we next develop techniques for using light irradiation to trigger self-assembly inside the confined space of liposomes. We encapsulate PA monomers that assemble under acidic conditions along with a photoacid generator inside liposomes. Upon exposure to 254 nm light, the PA monomers self assemble inside the liposome to form nanostructures, which we observe through a quick freeze/deep etch technique that allows us to look inside the liposomes by SEM and TEM. Last of all, the development and discovery of epitopes for targeting PA nanostructures to tumors are explored. Using phage display technology we generate two groups of peptide sequences, one of which can potentially

  10. Self-Assembling Peptide Amphiphiles for Targeted Drug Delivery

    Science.gov (United States)

    Moyer, Tyson

    The systemic delivery of therapeutics is currently limited by off-target side effects and poor drug uptake into the cells that need to be treated. One way to circumvent these issues is to target the delivery and release of therapeutics to the desired location while limiting systemic toxicity. Using self-assembling peptide amphiphiles (PAs), this work has investigated supramolecular nanostructures for the development of targeted therapies. Specifically, the research has focused on the interrelationships between presentation of targeting moeities and the control of nanostructure morphology in the context of systemic delivery for targeting cancer and vascular injuries. The self-assembly region of the PA was systematically altered to achieve control of nanostructure widths, from 100 nm to 10 nm, by the addition of valine-glutamic acid dimers into the chemical structure, subsequently increasing the degree of nanostructure twist. For the targeting of tumors, a homing PA was synthesized to include a dimeric, cyclic peptide sequence known to target the cancer-specific, death receptor 5 (DR5) and initiate apoptosis through the oligomerization of DR5. This PA presented a multivalent display of DR5-binding peptides, resulting in improved binding affinity measured by surface plasmon resonance. The DR5-targeting PA also showed enhanced efficacy in both in vitro and in vivo tumor models relative to non-targeted controls. Alternative modifications to the PA-based antitumor therapies included the use of a cytotoxic, membrane-lytic PA coassembled with a pegylated PA, which showed enhanced biodistribution and in vivo activity after coassembly. The functionalization of the hydrophobic core was also accomplished through the encapsulation of the chemotherapy camptothecin, which was shown to be an effective treatment in vivo. Additionally, a targeted PA nanostructure was designed to bind to the site of vascular intervention by targeting collagen IV. Following balloon angioplasty

  11. Amphiphilic semi-interpenetrating polymer networks using pulverized rubber

    Science.gov (United States)

    Shahidi, Nima

    Scrap rubber materials provide a significant challenge to either reuse or safe disposal. Every year, millions of tires are discarded to landfills in the United States, consuming a staggering amount of land space, creating a high risk for large fires, breeding mosquitoes that spread diseases, and wasting the planet's natural resources. This situation cannot be sustained. The challenge of reusing scrap rubber materials is mainly due to the crosslinked structure of vulcanized rubber that prevent them from melting and further processing for reuse. The most feasible recycling approach is believed to be a process in which the vulcanized rubber is first pulverized into a fine powder and then incorporated into new products. The production of fine rubber particles is generally accomplished through the use of a cryogenic process that is costly. Therefore, development of a cost effective technology that utilizes a large quantity of the scrap rubber materials to produce high value added materials is an essential element in maintaining a sustainable solution to rubber recycling. In this research, a cost effective pulverization process, solid state shear extrusion (SSSE), was modified and used for continuous pulverization of the rubber into fine particles. In the modified SSSE process, pulverization takes place at high compressive shear forces and a controlled temperature. Furthermore, an innovative particle modification process was developed to enhance the chemical structure and surface properties of the rubber particles for manufacturing of high value added products. Modification of rubber particles was accomplished through the polymerization of a hydrophilic monomer mixture within the intermolecular structure of the hydrophobic rubber particles. The resulting composite particles are considered as amphiphilic particulate phase semi-interpenetrating polymer networks (PPSIPNs). The modified rubber particles are water dispersible and suitable for use in a variety of aqueous media

  12. PARTITION-OPTIMIZED SINGLE EMULSION PARTICLES IMPROVE SUSTAINED RELEASE OF AMPHIPHILIC BUMPED KINASE INHIBITORS TO CONTROL MALARIA TRANSMISSION

    Directory of Open Access Journals (Sweden)

    Christina Yacoob

    2015-11-01

    Full Text Available Amphiphilic molecules are challenging to be incorporatedinto polymeric particles for sustained release due to their significant solubility in both water and organic solvent used in the fabrication process. Here, we investigated an extensive panel of fabrication methods for the incorporation and release of amphiphilic molecules, in particular, novel amphiphilic bumped kinase inhibitors (BKIs. Previously, BKIswere shown to reduce malaria transmission by blocking of gametocyte exflagellation. Prolonged BKI bioavailability for effective transmission blocking is crucial since infectious gametocytes circulate for several weeks inthe mammalian host, well beyond the half-life of BKIs. So far, delivery systems for sustained release of those BKIs have not been successfully formulated yet. Here we demonstrate that out of several delivery vehicles the partition-optimized single emulsion particles are the ideal system for incorporation and sustained release of amphiphilic BKIs. They increased the incorporation greater than 90% through optimized partitioning of amphiphilic molecules to the polymer phase and sustained release of BKIs up to several weeks with a reduction in the initial burst release. Overall this work provides a method for the incorporation and sustained release of amphiphilic BKIs, and can be adapted for other amphiphilic molecules.

  13. The encapsulation of an amphiphile into polystyrene microspheres of narrow size distribution

    Directory of Open Access Journals (Sweden)

    Pellach Michal

    2011-12-01

    Full Text Available Abstract Encapsulation of compounds into nano- or microsized organic particles of narrow size distribution is of increasing importance in fields of advanced imaging and diagnostic techniques and drug delivery systems. The main technology currently used for encapsulation of molecules within uniform template particles while retaining their size distribution is based on particle swelling methodology, involving penetration of emulsion droplets into the particles. The swelling method, however, is efficient for encapsulation only of hydrophobic compounds within hydrophobic template particles. In order to be encapsulated, the molecules must favor the hydrophobic phase of an organic/aqueous biphasic system, which is not easily achieved for molecules of amphiphilic character. The following work overcomes this difficulty by presenting a new method for encapsulation of amphiphilic molecules within uniform hydrophobic particles. We use hydrogen bonding of acid and base, combined with a pseudo salting out effect, for the entrapment of the amphiphile in the organic phase of a biphasic system. Following the entrapment in the organic phase, we demonstrated, using fluorescein and (antibiotic tetracycline as model molecules, that the swelling method usually used only for hydrophobes can be expanded and applied to amphiphilic molecules.

  14. New carbon-carbon linked amphiphilic carboranyl-porphyrins as boron neutron capture agents

    International Nuclear Information System (INIS)

    Novel amphiphilic carboranyl-porphyrins have been synthesized for Boron Neutron Capture Therapy (BNCT). These compounds have carbon-carbon bonds between the carborane residues and the porphyrin meso-phenyl groups, and contain 28-31% boron by weight . (author)

  15. Preparation of Vesicles and Nanoparticles of Amphiphilic Cyclodextrins Containing Labile Disulfide Bonds

    NARCIS (Netherlands)

    Nolan, Darren; Darcy, Raphael; Ravoo, Bart Jan

    2003-01-01

    Amphiphilic cyclodextrin derivatives were prepared in which a disulfide bond connects the hydrophobic substituents to the macrocycle. These compounds were obtained by 1,3-dicyclohexylcarbodiimide-mediated coupling reactions of heptakis(6-amino-6-deoxy)-B-cyclodextrins and disulfide-containing carbox

  16. Synthesis of Novel Amphiphilic Azobenzenes and X-ray Scattering Studies of Their Langmuir Monolayers

    DEFF Research Database (Denmark)

    Sørensen, Thomas Just; Kjær, Kristian; Breiby, Dag Werner;

    2008-01-01

    air-water interface, the amphiphilic azobenzenes form noncrystalline but stable Langmuir films that display an unusual reversible monolayer collapse close to 35 mN/m. The structures and phase transitions were studied by X-ray reflectivity (XR) and grazing-incidence X-ray diffraction, both utilizing...

  17. Tunable Hydrophobicity in DNA Micelles : Design, Synthesis, and Characterization of a New Family of DNA Amphiphiles

    NARCIS (Netherlands)

    Anaya, Milena; Kwak, Minseok; Musser, Andrew J.; Muellen, Klaus; Herrmann, Andreas; Müllen, Klaus

    2010-01-01

    This work describes the synthesis and characterization of a new family of DNA amphiphiles containing modified nucleobases. The hydrophobicity was imparted by the introduction of a dodec-1-yne chain at the 5-position of the uracil base, which allowed precise and simple tuning of the hydrophobic prope

  18. Inducing spin crossover in metallo-supramolecular polyelectrolytes through an amphiphilic phase transition.

    Science.gov (United States)

    Bodenthin, Yves; Pietsch, Ullrich; Möhwald, Helmuth; Kurth, Dirk G

    2005-03-01

    A phase transition in an amphiphilic mesophase is explored to deliberately induce mechanical strain in an assembly of tightly coupled metal ion coordination centers. Melting of the alkyl chains in the amphiphilic mesophase causes distortion of the coordination geometry around the central transition metal ion. As a result, the crystal field splitting of the d-orbital subsets decreases resulting in a spin transition from a low-spin to a high-spin state. The diamagnetic-paramagnetic transition is reversible. This concept is demonstrated in a metallo-supramolecular coordination polyelectrolyte-amphiphile complex self-assembled from ditopic bis-terpyridines, Fe(II) as central transition metal, and dialkyl phosphates as amphiphiles. The magnetic properties are studied in a Langmuir-Blodgett multilayer. The modularity of this concept provides extensive control of structure and function from molecular to macroscopic length scales and gives access to a wide range of new molecular magnetic architectures such as nanostructures, thin films, and liquid crystals. PMID:15740150

  19. Transfection of small numbers of human endothelial cells by electroporation and synthetic amphiphiles

    NARCIS (Netherlands)

    van Leeuwen, E B; van der Veen, A Y; Hoekstra, D; Engberts, J B; Halie, M R; van der Meer, J; Ruiters, M H

    1999-01-01

    OBJECTIVES: This study compared the efficiency of electroporation and synthetic amphiphiles. (SAINT-2pp/DOPE) in transfecting small numbers of human endothelial cells. METHODS AND RESULTS: Optimal transfection conditions were tested and appeared to be 400 V and 960 microF for electroporation and a 1

  20. Oxidized potato starch based thermoplastic films : Effect of combination of hydrophilic and amphiphilic plasticizers

    NARCIS (Netherlands)

    Niazi, Muhammad Bilal Khan; Broekhuis, Antonius A.

    2016-01-01

    Different combinations of hydrophilic (glycerol and water) and amphiphilic (isoleucine) plasticizers were studied in the production of thermoplastic starch (TPS) powders and films from oxidized potato starch. All powder samples had an irregular and shrivelled morphology. In all mixtures containing i

  1. Fabrication of honeycomb-structured poly(ethylene glycol)-block-poly(lactic acid) porous films and biomedical applications for cell growth

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Honeycomb-structured PEG-PLA porous films were fabricated. • The organization of pores depends on molecular weight ratio of PEG-to-PLA block. • The pores in the film were internally decorated with a layer of PEG. • The honeycomb-structured PEG-PLA film was suitable as a substrate for cell growth. - Abstract: A series of poly(ethylene glycol)-block-poly(lactic acid) (PEG-PLA) copolymers with a hydrophobic PLA block of different molecular weights and a fixed length hydrophilic PEG were synthesized successfully and characterized. These amphiphilic block copolymers were used to fabricate honeycomb-structured porous films using the breath figure (BF) templating technique. The surface topology and composition of the highly ordered pattern film were further characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. The results indicated that the PEG-to-PLA block molecular weight ratio influenced the BF film surface topology. The film with the best ordered pores was obtained with a PEG-to-PLA ratio of 2.0 × 103:3.0 × 104. The self-organization of the hydrophilic PEG chains within the pores was confirmed by XPS and fluorescence labeled PEG. A model is proposed to elucidate the stabilization process of the amphiphilic PEG-PLA aggregated architecture on the water droplet-based templates. In addition, GFP-U87 cell viability has been investigated by MTS test and the cell morphology on the honeycomb-structured PEG-PLA porous film has been evaluated using phase-contrast microscope. This porous film is shown to be suitable as a matrix for cell growth

  2. Fabrication of honeycomb-structured poly(ethylene glycol)-block-poly(lactic acid) porous films and biomedical applications for cell growth

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Bingjian [Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250199 (China); College of chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Normal University, Jinan 250014 (China); Zhu, Qingzeng, E-mail: qzzhu@sdu.edu.cn [Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250199 (China); Yao, Linli [Key Laboratory of the Ministry of Education for Experimental Teratology, Department of Histology and Embryology, Shandong University School of Medicine, 250012 Jinan (China); Hao, Jingcheng [Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250199 (China)

    2015-03-30

    Graphical abstract: - Highlights: • Honeycomb-structured PEG-PLA porous films were fabricated. • The organization of pores depends on molecular weight ratio of PEG-to-PLA block. • The pores in the film were internally decorated with a layer of PEG. • The honeycomb-structured PEG-PLA film was suitable as a substrate for cell growth. - Abstract: A series of poly(ethylene glycol)-block-poly(lactic acid) (PEG-PLA) copolymers with a hydrophobic PLA block of different molecular weights and a fixed length hydrophilic PEG were synthesized successfully and characterized. These amphiphilic block copolymers were used to fabricate honeycomb-structured porous films using the breath figure (BF) templating technique. The surface topology and composition of the highly ordered pattern film were further characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. The results indicated that the PEG-to-PLA block molecular weight ratio influenced the BF film surface topology. The film with the best ordered pores was obtained with a PEG-to-PLA ratio of 2.0 × 10{sup 3}:3.0 × 10{sup 4}. The self-organization of the hydrophilic PEG chains within the pores was confirmed by XPS and fluorescence labeled PEG. A model is proposed to elucidate the stabilization process of the amphiphilic PEG-PLA aggregated architecture on the water droplet-based templates. In addition, GFP-U87 cell viability has been investigated by MTS test and the cell morphology on the honeycomb-structured PEG-PLA porous film has been evaluated using phase-contrast microscope. This porous film is shown to be suitable as a matrix for cell growth.

  3. Large organized surface domains self-assembled from nonpolar amphiphiles.

    Science.gov (United States)

    Krafft, Marie Pierre

    2012-04-17

    For years, researchers had presumed that Langmuir monolayers of small C(n)F(2n+1)C(m)H(2m+1) (FnHm) diblock molecules (such as F8H16) consisted of continuous, featureless films. Recently we have discovered that they instead form ordered arrays of unusually large (~30-60 nm), discrete self-assembled surface domains or hemimicelles both at the surface of water and on solid substrates. These surface micelles differ in several essential ways from all previously reported or predicted molecular surface aggregates. They self-assemble spontaneously, even at zero surface pressure, depending solely on a critical surface concentration. They are very large (~100 times the length of the diblock) and involve thousands of molecules (orders of magnitude more than classical micelles). At the same time, the surface micelles are highly monodisperse and self-organize in close-packed hexagonal patterns (two-dimensional crystals). Their size is essentially independent from pressure, and they do not coalesce and are unexpectedly sturdy for soft matter (persisting even beyond surface film collapse). We and other researchers have observed large surface micelles for numerous diblocks, using Langmuir-Blodgett (LB) transfer, spin-coating and dip-coating techniques, or expulsion from mixed monolayers, and on diverse supports, establishing that hemimicelle formation and ordering are intrinsic properties of (perfluoroalkyl)alkanes. Notably, they involve "incomplete" surfactants with limited amphiphilic character, which further illustrates the outstanding capacity for perfluoroalkyl chains to promote self-assembly and interfacial film structuring. Using X-ray reflectivity, we determined a perfluoroalkyl-chain-up orientation. Theoretical investigations assigned self-assembly and hemimicelle stability to electrostatic dipole-dipole interactions at the interface between Fn- and Hm-sublayers. Grazing-incidence small-angle X-ray scattering (GISAXS) data collected directly on the surface of water

  4. Structure and reactions in some amphiphilic association systems

    Science.gov (United States)

    Guo, Rong

    1999-06-01

    surfactant CTAB system with various co-surfactants: n-pentanol, n-octanol, n-valeric acid, and n-caproic acid, but not in SDS or Triton X-100 systems. Presence of VC stabilizes both W/O and O/W microemulsions but destabilizes the lamellar liquid crystalline phase. Hence, the "phase transition" from the lamellar liquid crystalline phase to the isotropic phase of O/W, W/O and bicontinuous structure phase occurs with the addition of VC. The hydrotropic action of VC has been used in sunscreens to increase the solubility of sunscreen E 557. The UV absorption spectra of E557 in various media surprisingly had a dependence on the colloid structure. A new method, the preparation of water-soluble nanoparticles, has been found by employing the effect of the penetration of solvent from water layer to amphiphilic layer in lamellar liquid crystals on the solubility of inorganic salts. Water-insoluble nanoparticles have been synthesized by the reaction of two water-soluble inorganic salts in the lamellar liquid crystal. The particle size is less than 10nm and can be controlled by the thickness of the solvent layer in the lamellar liquid crystal. The lamellar liquid crystalline phase of the Triton X-100/decanol/water system has been chosen as a medium because of its large lamellar liquid crystal region and its stability when inorganic salts are added.

  5. Adsorption of phthalic acid esters (PAEs) by amphiphilic polypropylene nonwoven from aqueous solution: the study of hydrophilic and hydrophobic microdomain.

    Science.gov (United States)

    Zhou, Xiangyu; Wei, Junfu; Zhang, Huan; Liu, Kai; Wang, Han

    2014-05-30

    A kind of amphiphilic polypropylene nonwoven with hydrophilic and hydrophobic microdomain was prepared through electron beam induced graft polymerization and subsequent ring opening reaction and then utilized in the adsorption of phthalic acid esters (PAEs). To elucidate the superiority of such amphiphilic microdomain, a unique structure without hydrophilic part was constructed as comparison. In addition, the adsorption behaviors including adsorption kinetics, isotherms and pH effect were systematically investigated. The result indicated that the amphiphilic structure and the synergy between hydrophilic and hydrophobic microdomain could considerably improve the adsorption capacities, rate and affinity. Particularly the existence of hydrophilic microdomain could reduce the diffusion resistance and energy barrier in the adsorption process. These adsorption results showed that the amphiphilic PP nonwoven have the potential to be used in environmental application.

  6. Oriented Poly(dialkylstannane)s

    DEFF Research Database (Denmark)

    Choffat, Fabien; Fornera, Sara; Smith, Paul;

    2008-01-01

    The inorganic (or 'organometallic') polymers poly(dibutylstannane), poly(dioctylstannane), and poly(didodecylstannane) have been oriented by shear forces, the tensile drawing of blends with polyethylene, and deposition from solution onto glass slides coated with all oriented, friction......-deposited poly(tetrafluoroethylene) (PTFE) layer. Orientation of the polystannanes has been examined by polarization microscopy, UV-vis spectroscopy with polarized light, and X-ray diffraction and their direction is found to depend on the length of the alkyl side groups and the method of orientation. Remarkably...

  7. Photophysical and photochemical studies of a novel amphiphilic zinc phthalocyanine and its interaction with calf thymus DNA

    Science.gov (United States)

    Yuan, Linxin; Gui, Li; Wang, Yue; Zhang, Quanquan; Zhou, Lin; Wei, Shaohua

    2016-04-01

    β-tetra (aminophenoxy) sulfonic substituted zinc phthalocyanines (SNZnPc), a novel amphiphilic zinc phthalocyanine (Pc), was synthesized. The photophysical, photochemical, and photobiology properties were studied. Results indicated that the synthesized SNZnPc has good amphiphilic property and high reactive oxygen species (ROSs) generation ability. Furthermore, SNZnPc has strong affinity to calf thymus DNA (CT-DNA) through intercalation ways and can effectively cleavage CT-DNA after irradiation by light with appropriate wavelength.

  8. Synthesis of a new generation of amphiphiles with multi-cryptand headgroups: A comparative study at air–water interface

    Indian Academy of Sciences (India)

    B Sarkar; R K Gupta; R A Singh; P K Bharadwaj

    2008-06-01

    A laterally non-symmetric aza cryptand has been derivatized with two hydrophobic chains to afford amphiphiles with one cryptand headgroup and two hydrophobic tails. Three such units readily attach to 1,3,5-benzenetricarbonyl trichloride, to form a new generation of amphiphilic molecules with three cryptand headgroups and six hydrophobic chains. These molecules are studied at the air–water interface in a Langmuir trough. They readily form LB-films on a number of substrates that are characterized.

  9. Photophysical and photochemical studies of a novel amphiphilic zinc phthalocyanine and its interaction with calf thymus DNA.

    Science.gov (United States)

    Yuan, Linxin; Gui, Li; Wang, Yue; Zhang, Quanquan; Zhou, Lin; Wei, Shaohua

    2016-04-01

    β-tetra (aminophenoxy) sulfonic substituted zinc phthalocyanines (SNZnPc), a novel amphiphilic zinc phthalocyanine (Pc), was synthesized. The photophysical, photochemical, and photobiology properties were studied. Results indicated that the synthesized SNZnPc has good amphiphilic property and high reactive oxygen species (ROSs) generation ability. Furthermore, SNZnPc has strong affinity to calf thymus DNA (CT-DNA) through intercalation ways and can effectively cleavage CT-DNA after irradiation by light with appropriate wavelength.

  10. Preparation, Characterization, and Biological Evaluation of Poly(Glutamic Acid-b-Polyphenylalanine Polymersomes

    Directory of Open Access Journals (Sweden)

    Evgenia Vlakh

    2016-06-01

    Full Text Available Different types of amphiphilic macromolecular structures have been developed within recent decades to prepare the polymer particles considered as drug delivery systems. In the present research the series of amphiphilic block-copolymers containing poly(glutamatic acid as hydrophilic, and polyphenylalanine as hydrophobic blocks was synthesized and characterized. Molecular weights for homo- and copolymers were determined by gel-permeation chromatography (GPC and amino acid analysis, respectively. The copolymers obtained were applied for preparation of polymer particles. The specific morphology of prepared polymerosomes was proved using transmission electron microscopy (TEM. The influence on particle size of polymer concentration and pH used for self-assembly, as well as on the length of hydrophobic and hydrophilic blocks of applied copolymers, was studied by dynamic light scattering (DLS. Depending on different experimental conditions, the formation of nanoparticles with sizes from 60 to 350 nm was observed. The surface of polymersomes was modified with model protein (enzyme. No loss in biocatalytic activity was detected. Additionally, the process of encapsulation of model dyes was developed and the possibility of intracellular delivery of the dye-loaded nanoparticles was proved. Thus, the nanoparticles discussed can be considered for the creation of modern drug delivery systems.

  11. Adsorption of phthalic acid esters (PAEs) by amphiphilic polypropylene nonwoven from aqueous solution: The study of hydrophilic and hydrophobic microdomain

    International Nuclear Information System (INIS)

    Highlights: • Amphiphilic PP-g-GMA-OA nonwoven was prepared and characterized. • Synergy between hydrophilic and hydrophobic microdomain was elucidated. • The effects of hydrophilic microdomain on diffusion resistance and energy barrier were elucidated. • Adsorbent material with amphiphilic structures showed faster adsorption rate and lager adsorption capacity. - Abstract: A kind of amphiphilic polypropylene nonwoven with hydrophilic and hydrophobic microdomain was prepared through electron beam induced graft polymerization and subsequent ring opening reaction and then utilized in the adsorption of phthalic acid esters (PAEs). To elucidate the superiority of such amphiphilic microdomain, a unique structure without hydrophilic part was constructed as comparison. In addition, the adsorption behaviors including adsorption kinetics, isotherms and pH effect were systematically investigated. The result indicated that the amphiphilic structure and the synergy between hydrophilic and hydrophobic microdomain could considerably improve the adsorption capacities, rate and affinity. Particularly the existence of hydrophilic microdomain could reduce the diffusion resistance and energy barrier in the adsorption process. These adsorption results showed that the amphiphilic PP nonwoven have the potential to be used in environmental application

  12. SYNTHESIS OF pH-RESPONSIVE AMPHIPHILIC DIBLOCK COPOLYMERS CONTAINING POLYISOBUTYLENE via OXYANION-INITIATED POLYMERIZATION AND THEIR MULTIPLE SELF-ASSEMBLY MORPHOLOGIES

    Institute of Scientific and Technical Information of China (English)

    Huai-chao Wang; Ming-zu Zhang; Pei-hong Ni; Jin-lin He; Ying Hao; Yi-xian Wu

    2013-01-01

    Two pH-responsive amphiphilic diblock copolymers,namely polyisobutylene-block-poly[2-(N,N-dimethylamino)ethyl methacrylate] (PIB-b-PDMAEMA) and polyisobutylene-block-poly(metharylic acid) (PIB-b-PMAA),were synthesized via oxyanion-initiated polymerization,and their multiple self-assembly behaviors have been studied.An exo-o1efin-terminated highly reactive polyisobutylene (HRPIB) was first changed to hydroxyl-terminated PIB (PIB-OH) via hydroboration-oxidation of C=C double bond in the chain end,and then reacted with KH to yield a potassium alcoholate of PIB (PIB-O-K+).PIB-O-K+ was immediately used as a macroinitiator to polymerize DMAEMA monomer,resulting in a cationic diblock copolymer PIB-b-PDMAEMA.With the similar synthesis procedure,the anionic diblock copolymer PIB-b-PMAA could be prepared via a combination of oxyanion-initiated polymerization of tert-butyl methacrylate (tBMA) and subsequent hydrolysis of tert-butyl ester groups in PtBMA block.The functional PIB and block copolymers have been fully characterized by 1H-NMR,FT-IR spectroscopy,and gel permeation chromatography (GPC).These samples allowed us to systematically investigate the effects of block composition on the pH responsivity and various self-assembled morphologies of the copolymers in THF/water mixed solvent.Transmission electron microscopy (TEM) images revealed that these diblock copolymers containing small amount of original PIB without exo-olefin-terminated group are able to self-assemble into micelles,vesicles with different particle sizes and cylindrical aggregates,depending on various factors including block copolymer composition,solvent polarity and pH value.

  13. Multi-Composite Bioactive Osteogenic Sponges Featuring Mesenchymal Stem Cells, Platelet-Rich Plasma, Nanoporous Silicon Enclosures, and Peptide Amphiphiles for Rapid Bone Regeneration

    Directory of Open Access Journals (Sweden)

    Dongmei Fan

    2011-06-01

    Full Text Available A novel bioactive sponge was created with a composite of type I collagen sponges or porous poly(e-caprolactone (PCL scaffolds, platelet-rich plasma (PRP, BMP2-loaded nanoporous silicon enclosure (NSE microparticles, mineralizing peptide amphiphiles (PA, and mesenchymal stem cells (MSC. Primary MSC from cortical bone (CB  tissue proved to form more and larger colony units, as well as produce more mineral matrix under osteogenic differentiation, than MSC from bone marrow (BM. Coating pre-treatments were optimized for maximum cell adhesion and mineralization, while a PRP-based gel carrier was created to efficiently deliver and retain MSC and  microparticles within a porous scaffold while simultaneously promoting cell recruitment, proliferation, and angiogenesis. Components and composite sponges were evaluated for osteogenic differentiation in vitro. Osteogenic sponges were loaded with MSC, PRP, PA, and NSE and implanted subcutaneously in rats to evaluate the formation of bone tissue and angiogenesis in vivo. It was found that the combination of a collagen sponge with CB MSC, PRP, PA, and the BMP2-releasing NSE formed the most bone and was most vascularized by four weeks compared to analogous composites featuring BM MSC or PCL or lacking PRP, PA, and NSE. This study indicates that CB MSC should be considered as an alternative to marrow as a source of stem cells, while the PRP-PA cell and microparticle delivery system may be utilized for diverse tissue engineering applications.

  14. Modification effects of amphiphilic comb-like polysiloxane containing polyether side chains on the PVDF membranes prepared via phase inversion process

    Institute of Scientific and Technical Information of China (English)

    Yanling QIAN; Jianhua WANG; Baoku ZHU; Mei ZHANG; Chunhui DU; Youyi XU

    2008-01-01

    Amphiphilic comb-like polysiloxane (ACPS) containing polyether side chains was used as the modifica-tion reagent in the preparation of hydrophilic porous poly (vinylidene fluoride) (PVDF) membranes via a phase inversion process. The effects of ACPS on morphology, crystallinity, mechanical properties, reservation of ACPS in the phase inversion process, chemical structure, hydro-philicity and filterability performance of porous PVDF membranes were discussed. It was found that the addition of ACPS would result in the delayed demixing which yields "sponge-like" sublayers and longer crystallization time during the membrane formation process. It was revealed that O/F ratios of the bulk membrane were almost the same as those of the corresponding casting solutions which obviously indicated the high reservation of ACPS in the membrane formation process. The fact that the O/F ratios in the membrane surface layers were much higher than those in the bulk membrane proved the enrichment of ACPS on the surface. The filterability experiments and water contact angle testing proved the hydrophilicity of the blend membranes. Through a schem-atic model, the mechanism relating the membrane struc-ture and performance was interpreted. From the observed results, it can be concluded that ACPS acts as a potential candidate material for preparing PVDF membranes with extraordinary hydrophilicity and filterability.

  15. Release kinetics of controlled release formulations of thiamethoxam employing nano-ranged amphiphilic PEG and diacid based block polymers in soil.

    Science.gov (United States)

    Sarkar, Dhruba Jyoti; Kumar, Jitendra; Shakil, N A; Walia, S

    2012-01-01

    Amphiphilic copolymers, synthesized from poly(ethylene glycols) and various aliphatic and aromatic diacids, which self-assemble into nanomicellar aggregates in aqueous media, were used to develop controlled release (CR) formulations of thiamethoxam (3-(2-chloro-1,3-thiazol-5-ylmethyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro)amine) using encapsulation technique Formulations were characterised by Infrared (IR) spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscope (TEM). Encapsulation efficiency, loading capacity and stability after accelerated storage test of the developed formulations were checked. The kinetics of thiamethoxam, released in sandy loam soil from the different formulations was studied. Release from the commercial formulation was faster than the CR formulations. The time taken for release of 50 % of thiamethoxam ranged from 3.56 to 6.07 days for the CR formulations. Although the diffusion exponent (n value) of thiamethoxam in soil ranged from 0.532 to 0.881 in the tested formulations showing non-Fickian transport. These CR formulations may be used in safer, effective and economic crop protection. PMID:22702832

  16. Atomistic Simulations of Poly(N-isopropylacrylamide) Surfactants in Water

    Science.gov (United States)

    Abbott, Lauren J.; Stevens, Mark J.

    2015-03-01

    The amphiphilic polymer poly(N-isopropylacrylamide) (PNIPAM) displays a sharp phase transition at its LCST around 32 °C, which results from competing interactions of the hydrophobic and hydrophilic groups with water. This thermoresponsive behavior can be exploited in more complex architectures, such as block copolymers or surfactants, to provide responsive PNIPAM head groups. In these systems, however, changes to the hydrophobic/hydrophilic balance can alter the transition behavior. In this work, we perform atomistic simulations of PNIPAM-alkyl surfactants to study the temperature dependence of their structures. A single chain of the surfactant does not show temperature-responsive behavior. Instead, below and above the LCST of PNIPAM, the surfactant folds to bring the hydrophobic alkyl tail in contact with the PNIPAM backbone, shielding it from water. In addition to single chains, we explore the self-assembly of multiple surfactants into micelles and how the temperature-dependent behavior is changed. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  17. Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene.

    Science.gov (United States)

    Lumholdt, Ludmilla; Fourmentin, Sophie; Nielsen, Thorbjørn T; Larsen, Kim L

    2014-01-01

    Polypropylene nonwovens were functionalised using a self-assembled, amphiphilic cyclodextrin coating and the potential for water purification by removal of pollutants was studied. As benzene is one of the problematic compounds in the Water Framework Directive, six volatile organic compounds (benzene and five benzene-based substances) were chosen as model compounds. The compounds were tested as a mixture in order to provide a more realistic situation since the wastewater will be a complex mixture containing multiple pollutants. The volatile organic compounds are known to form stable inclusion complexes with cyclodextrins. Six different amphiphilic cyclodextrin derivatives were synthesised in order to elucidate whether or not the uptake abilities of the coating depend on the structure of the derivative. Headspace gas chromatography was used for quantification of the uptake exploiting the volatile nature of benzene and its derivatives. The capacity was shown to increase beyond the expected stoichiometries of guest-host complexes with ratios of up to 16:1. PMID:25550739

  18. Terpene and dextran renewable resources for the synthesis of amphiphilic biopolymers.

    Science.gov (United States)

    Alvès, Marie-Hélène; Sfeir, Huda; Tranchant, Jean-François; Gombart, Emilie; Sagorin, Gilles; Caillol, Sylvain; Billon, Laurent; Save, Maud

    2014-01-13

    The present work shows the synthesis of amphiphilic polymers based on the hydrophilic dextran and the hydrophobic terpenes as renewable resources. The first step concerns the synthesis of functional terpene molecules by thiol-ene addition chemistry involving amino or carboxylic acid thiols and dihydromyrcenol terpene. The terpene-modified polysaccharides were subsequently synthesized by coupling the functional terpenes with dextran. A reductive amination step produced terpene end-modified dextran with 94% of functionalization, while the esterification step produced three terpene-grafted dextrans with a number of terpene units per dextran of 1, 5, and 10. The amphiphilic renewable grafted polymers were tested as emulsifiers for the stabilization of liquid miniemulsion of terpene droplets dispersed in an aqueous phase. The average hydrodynamic diameter of the stable droplets was observed at about 330 nm.

  19. Trapping of polycyclic aromatic hydrocarbons by amphiphilic cyclodextrin functionalized polypropylene nonwovens

    DEFF Research Database (Denmark)

    Lumholdt, Ludmilla; Nielsen, Ronnie Bo Højstrup; Larsen, Kim Lambertsen

    Recently, there has been an augmented focus on the increasing amount of pesticides, drug residues and endocrine disruptors present in waste and drinking water1. These pollutants represent a challenge in water purification since they may be hazardous to human health even in low doses2. Cyclodextrins...... of the textile fibers. In this study we present the ability of amphiphilic CD coated polypropylene nonwovens to trap 8 different polycyclic aromatic hydrocarbons/endocrine disruptors from aqueous solutions thus demonstrating the potential of using the amphiphilic cyclodextrins for water purification....... (CDs) are known to be able to form inclusion complexes with a large range of the unwanted pollutantse.g. 3 but in order to utilise this ability to purify water, the CDs must be immobilised on a surface, for instance, a membrane filter. We have developed a simple and fast method...

  20. REVIEWS OF TOPICAL PROBLEMS: Supermolecular liquid-crystalline structures in solutions of amphiphilic molecules

    Science.gov (United States)

    Vedenov, A. A.; Levchenko, E. B.

    1983-09-01

    This paper reviews the physical properties of liquid-crystalline phases arising in solutions containing molecules of amphiphilic substances. The basic characteristics of micelle formation in dilute solutions, models of sphere-disk or sphere-cylinder structural transformations, as well as phase transitions related to the appearance of lyotropic mesophases in the system, including nematic, lamellar, hexagonal, and others, are examined. The results of experimental and theoretical investigation of "solvation" forces acting between micelles in the solvent, as well as recently studied models of swelling of lamellar phases are presented. The phenomena occurring near the inversion point of microemulsions in amphiphile-oil-water systems are examined briefly. The role of liquid-crystalline ordering in some biological systems is discussed.

  1. Amphiphilic block copolymers in oil-water-surfactant mixtures: efficiency boosting, structure, phase behaviour and mechanism

    Science.gov (United States)

    Gompper, G.; Richter, D.; Strey, R.

    2001-10-01

    The effect of amphiphilic block copolymers on the phase behaviour and structure of ternary microemulsions in water, oil and non-ionic surfactant mixtures is reviewed. Recent experiments have revealed that the addition of small amounts of polyethylenepropylene-polyethyleneoxide block copolymer to the ternary systems leads to a dramatic increase in the volumes of oil and water solubilized into a bicontinuous microemulsion for a given surfactant volume fraction. While phase diagrams directly show the power of the amphiphilic block copolymers as efficiency boosters, the theoretical analysis in terms of bending energy discloses the mechanism for the efficiency boosting as due to the variation of the surfactant film curvature elasticity by tethered polymers in the form of mushrooms at the interface. Neutron scattering experiments employing a high-precision two-dimensional contrast variation technique confirm this picture and demonstrate that the polymer molecules uniformly decorate the surfactant film.

  2. Micelle assembly. Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles.

    Science.gov (United States)

    Qiu, Huibin; Hudson, Zachary M; Winnik, Mitchell A; Manners, Ian

    2015-03-20

    Self-assembly of molecular and block copolymer amphiphiles represents a well-established route to micelles with a wide variety of shapes and gel-like phases. We demonstrate an analogous process, but on a longer length scale, in which amphiphilic P-H-P and H-P-H cylindrical triblock comicelles with hydrophobic (H) or polar (P) segments that are monodisperse in length are able to self-assemble side by side or end to end in nonsolvents for the central or terminal segments, respectively. This allows the formation of cylindrical supermicelles and one-dimensional (1D) or 3D superstructures that persist in both solution and the solid state. These assemblies possess multiple levels of structural hierarchy in combination with existence on a multimicrometer-length scale, features that are generally only found in natural materials. PMID:25792323

  3. Super-resolution microscopy reveals structural diversity in molecular exchange among peptide amphiphile nanofibres

    Science.gov (United States)

    da Silva, Ricardo M. P.; van der Zwaag, Daan; Albertazzi, Lorenzo; Lee, Sungsoo S.; Meijer, E. W.; Stupp, Samuel I.

    2016-05-01

    The dynamic behaviour of supramolecular systems is an important dimension of their potential functions. Here, we report on the use of stochastic optical reconstruction microscopy to study the molecular exchange of peptide amphiphile nanofibres, supramolecular systems known to have important biomedical functions. Solutions of nanofibres labelled with different dyes (Cy3 and Cy5) were mixed, and the distribution of dyes inserting into initially single-colour nanofibres was quantified using correlative image analysis. Our observations are consistent with an exchange mechanism involving monomers or small clusters of molecules inserting randomly into a fibre. Different exchange rates are observed within the same fibre, suggesting that local cohesive structures exist on the basis of β-sheet discontinuous domains. The results reported here show that peptide amphiphile supramolecular systems can be dynamic and that their intermolecular interactions affect exchange patterns. This information can be used to generate useful aggregate morphologies for improved biomedical function.

  4. Replication of simulated prebiotic amphiphile vesicles controlled by experimental lipid physicochemical properties

    International Nuclear Information System (INIS)

    We present a new embodiment of the graded autocatalysis replication domain (GARD) for the growth, replication and evolution of lipid vesicles based on a semi-empirical foundation using experimentally measured kinetic values of selected extant lipid species. Extensive simulations using this formalism elucidated the details of the dependence of the replication and properties of the vesicles on the physicochemical properties and concentrations of the lipids, both in the environment and in the vesicle. As expected, the overall concentration and number of amphiphilic components strongly affect average replication time. Furthermore, variations in acyl chain length and unsaturation of vesicles also influence replication rate, as do the relative concentrations of individual lipid types. Understanding of the dependence of replication rates on physicochemical parameters opens a new direction in the study of prebiotic vesicles and lays the groundwork for future studies involving the competition between lipid vesicles for available amphiphilic monomers

  5. Amphiphilic block copolymers as efficiency boosters in microemulsions a SANS investigation of the role of polymers

    CERN Document Server

    Endo, H; Mihailescu, M; Monkenbusch, M; Gompper, G; Richter, D; Jakobs, B; Sottmann, T; Strey, R

    2002-01-01

    The effect of amphiphilic block copolymers on ternary microemulsions (water, oil and non-ionic surfactant) is investigated. Small amounts of PEP-PEO block copolymer lead to a dramatic expansion of the one-phase region where water and oil can be solubilized by the mediation of surfactant molecules. Small-angle neutron-scattering experiments employing a high-precision two-dimensional contrast-variation technique demonstrate that the polymer is distributed uniformly on the surfactant membrane, where it modifies the membrane curvature elasticity. Furthermore, a new approach to determine the bending rigidity of an amphiphilic membrane is proposed, which is precise enough to measure the logarithmic scale dependence of the bending rigidity and its universal prefactor in bicontinuous microemulsions. (orig.)

  6. Amphiphilic Cellulose Ethers Designed for Amorphous Solid Dispersion via Olefin Cross-Metathesis.

    Science.gov (United States)

    Dong, Yifan; Mosquera-Giraldo, Laura I; Taylor, Lynne S; Edgar, Kevin J

    2016-02-01

    The design of cellulose ether-based amphiphiles has been difficult and limited because of the harsh conditions typically required for appending ether moieties to cellulose. Olefin cross-metathesis recently has been shown to be a valuable approach for appending a variety of functional groups to cellulose ethers and esters, provided that an olefin handle for metathesis can be attached. This synthetic pathway gives access to these functional derivatives under very mild conditions and at high efficiency. Modification of ethyl cellulose by metathesis to prepare useful derivatives, for example, for solubility and bioavailability enhancement of drugs by amorphous solid dispersion (ASD), has been limited by the low DS(OH) of commercial ethyl cellulose derivatives. This is problematic because ethyl cellulose is otherwise a very attractive substrate for synthesis of amphiphilic derivatives by olefin metathesis. Herein we explore two methods for opening up this design space for ether-based amphiphiles, for example, permitting synthesis of more hydrophilic derivatives. One approach is to start with the more hydrophilic commercial methyl cellulose, which contains much higher DS(OH) and therefore is better suited for introduction of high DS of olefin metathesis "handles". In another approach, we explored a homogeneous one-pot synthesis methodology from cellulose, where controlled DS of ethyl groups was introduced at the same time as the ω-unsaturated alkyl groups, thereby permitting complete control of DS(OH), DS(Et), and ultimately DS of the functional group added by metathesis. We describe the functionalized derivatives available by these successful approaches. In addition, we explore new methods for reduction of the unsaturation in initial metathesis products to provide robust methods for enhancing product stability against further radical-catalyzed reactions. We demonstrate initial evidence that the products show strong promise as amphiphilic matrix polymers for amorphous

  7. Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene

    OpenAIRE

    Ludmilla Lumholdt; Sophie Fourmentin; Nielsen, Thorbjørn T; Larsen, Kim L.

    2014-01-01

    Polypropylene nonwovens were functionalised using a self-assembled, amphiphilic cyclodextrin coating and the potential for water purification by removal of pollutants was studied. As benzene is one of the problematic compounds in the Water Framework Directive, six volatile organic compounds (benzene and five benzene-based substances) were chosen as model compounds. The compounds were tested as a mixture in order to provide a more realistic situation since the wastewater will be a complex mixt...

  8. Amphiphilic zein hydrolysate as a novel nano-delivery vehicle for curcumin.

    Science.gov (United States)

    Wang, Yong-Hui; Wang, Jin-Mei; Yang, Xiao-Quan; Guo, Jian; Lin, Yuan

    2015-08-01

    In this paper, we developed amphiphilic zein hydrolysate (ZH) as a novel delivery vehicle, which could be used for preparing curcumin (Cur) nanocomplexes. These ZH-Cur nanocomplexes exhibited spherical morphology with a monodisperse size distribution (oil-water interface, as confirmed by micelle formation and dynamic interfacial adsorption respectively. Fluorescence titration and FTIR results indicated the existence of strong hydrophobic interactions between ZH and Cur, which was responsible for the complexation. PMID:26134524

  9. Extracellular matrix formation in self-assembled minimalistic bioactive hydrogels based on aromatic peptide amphiphiles

    OpenAIRE

    ZHOU, MI; Ulijn, Rein V.; Gough, Julie E

    2014-01-01

    The hitherto inconsistency in clinical performance for engineered skin drives the current development of novel cell-scaffolding materials; one challenge is to only extract essential characteristics from the complex native ECM (extracellular matrix) and incorporate them into a scaffold with minimal complexity to support normal cell functions. This study involved small-molecule-based bioactive hydrogels produced by the co-assembly of two aromatic peptide amphiphiles: Fmoc-FF (Fluorenylmethoxyca...

  10. Amphiphilic Cellulose Ethers Designed for Amorphous Solid Dispersion via Olefin Cross-Metathesis.

    Science.gov (United States)

    Dong, Yifan; Mosquera-Giraldo, Laura I; Taylor, Lynne S; Edgar, Kevin J

    2016-02-01

    The design of cellulose ether-based amphiphiles has been difficult and limited because of the harsh conditions typically required for appending ether moieties to cellulose. Olefin cross-metathesis recently has been shown to be a valuable approach for appending a variety of functional groups to cellulose ethers and esters, provided that an olefin handle for metathesis can be attached. This synthetic pathway gives access to these functional derivatives under very mild conditions and at high efficiency. Modification of ethyl cellulose by metathesis to prepare useful derivatives, for example, for solubility and bioavailability enhancement of drugs by amorphous solid dispersion (ASD), has been limited by the low DS(OH) of commercial ethyl cellulose derivatives. This is problematic because ethyl cellulose is otherwise a very attractive substrate for synthesis of amphiphilic derivatives by olefin metathesis. Herein we explore two methods for opening up this design space for ether-based amphiphiles, for example, permitting synthesis of more hydrophilic derivatives. One approach is to start with the more hydrophilic commercial methyl cellulose, which contains much higher DS(OH) and therefore is better suited for introduction of high DS of olefin metathesis "handles". In another approach, we explored a homogeneous one-pot synthesis methodology from cellulose, where controlled DS of ethyl groups was introduced at the same time as the ω-unsaturated alkyl groups, thereby permitting complete control of DS(OH), DS(Et), and ultimately DS of the functional group added by metathesis. We describe the functionalized derivatives available by these successful approaches. In addition, we explore new methods for reduction of the unsaturation in initial metathesis products to provide robust methods for enhancing product stability against further radical-catalyzed reactions. We demonstrate initial evidence that the products show strong promise as amphiphilic matrix polymers for amorphous

  11. Langmuir-Blodgett Films and Calcium Ion Coordination of Biliverdin and Its Amphiphilic Derivatives

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Monolayer formation and LB film fabrication of amphiphilic derivative of biliverdin 1,diododecyl biliverdinamide [B(CONHC12H25)2,2] at an air-water interface on pure water subphase and subphase containing calcium ion were investigated and compared with 1.The coordination in ordered molecular films is much different from that in bulk solution.The formation of ligand-calcium complex was confirmed by X-ray photoelectron spectroscopy.

  12. Bioinspired amphiphilic phosphate block copolymers as non-fluoride materials to prevent dental erosion

    OpenAIRE

    Lei, Yanda; Wang, Tongxin; Mitchell, James W; Zaidel, Lynette; Qiu, Jianhong; Kilpatrick-Liverman, LaTonya

    2014-01-01

    Inspired by the fact that certain natural proteins, e.g. casein phosphopeptide or amelogenin, are able to prevent tooth erosion (mineral loss) and to enhance tooth remineralization, a synthetic amphiphilic diblock copolymer, containing a hydrophilic methacryloyloxyethyl phosphate block (MOEP) and a hydrophobic methyl methacrylate block (MMA), was designed as a novel non-fluoride agent to prevent tooth erosion under acidic conditions. The structure of the polymer, synthesized by reversible add...

  13. Synthesis and self-assembly of multiple thermoresponsive amphiphilic block copolymers

    OpenAIRE

    Weiß, Jan

    2011-01-01

    In the present thesis, the self-assembly of multi thermoresponsive block copolymers in dilute aqueous solution was investigated by a combination of turbidimetry, dynamic light scattering, TEM measurements, NMR as well as fluorescence spectroscopy. The successive conversion of such block copolymers from a hydrophilic into a hydrophobic state includes intermediate amphiphilic states with a variable hydrophilic-to-lipophilic balance. As a result, the self-organization is not following an all-or-...

  14. Exploring single chain amphiphile self-assembly and their possible roles in light transduction

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain

    2011-01-01

    Self-assembled structures of single-chain amphiphiles have been used as hosts for biochemical, and chemical reactions. Their use as models for protocells (i.e., precursors to the first biological cells) has been extensively researched by various groups because the availability of single chain amp...... network. References 1 Cape, J., et al. (2011) Chem. Sci., 2 (4), 661-667. 2 Maurer, S. E., et al. (2009) Astrobiology, 9, 979-987. 3 Caschera, F., et al. Langmuir, In press....

  15. Elisapterosin F: a polycyclic gorgonian-derived diterpene with a facially amphiphilic structure

    Science.gov (United States)

    Rodríguez, Ileana I.; Rodríguez, Abimael D.

    2009-01-01

    Analysis of the terpene metabolites of Pseudopterogorgia elisabethae collected in San Andrés island, Colombia has resulted in the discovery of a novel metabolite, elisapterosin F (1). The tangled molecular structure of 1, which was elucidated after extensive spectroscopic data interpretation, possesses hydrophilic and hydrophobic groups located on two opposite faces, rather than at two ends as in the more conventional head/tail amphiphiles. PMID:20161151

  16. Carboxymethyl chitosan-graft-phosphatidylethanolamine : amphiphilic matrices for controlled drug delivery

    OpenAIRE

    Prabaharan, M.; Reis, R. L.; Mano, J. F.

    2007-01-01

    Modified carboxymethyl chitosan (CMC) containing phosphatidylethanolamine (PEA) groups were synthesized by a 1- ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)-mediated coupling reaction. The structure of the modified CMC exhibiting an amphiphilic character was analysed by FT-IR and 1H NMR. CMC-g-PEA beads were prepared with sodium tripolyphosphate (TPP) by ionic-crosslinking. The beads sizes were in range from 800 to 1200 lm and encapsulation efficiencies of drug were more than...

  17. A comparative study of the physicochemical properties of perfluorinated and hydrogenated amphiphiles.

    Science.gov (United States)

    Blanco, Elena; González-Pérez, Alfredo; Ruso, Juan M; Pedrido, Rosa; Prieto, Gerardo; Sarmiento, Félix

    2005-08-01

    In this work we studied and compared the physicochemical properties of perfluorinated (sodium perfluoroheptanoate, C7FONa, and perfluorooctanoate, C8FONa) and hydrogenated (sodium octanoate, C8HONa, decanoate, C10HONa, and dodecanoate, C12HONa) amphiphiles. First, we determined their Krafft points to study the solubility and appropriate temperature range of micellization of these compounds. The critical micelle concentration (cmc) and ionization degree of micellization (beta) as a function of temperature (T) were estimated from conductivity data. Plots of cmc vs T appear to follow the typical U-shaped curve with a minimum T(min). The results show that the surfactants with CF2/CH2 ratio of 1.5 between alkyl chains (C12HONa-C8FONa and C10HONa-C7FONa) have nearly the same minimum value for cmc against temperature. The comparison between the cmc of hydrogenated amphiphiles and the corresponding perfluorinated amphiphiles must be done at this point. Thermodynamic functions of micellization were obtained by applying different theoretical models and choosing the one that best fit our experimental data. Although perfluorinated and hydrogenated amphiphiles present similar thermodynamic behavior, we have found a variation of 1.3 to 1.7 in the CF2/CH2 ratio, which did not remain constant with temperature. In the second part of this study the apparent molar volumes and adiabatic compressibilities were determined from density and ultrasound velocity measurements. Apparent molar volumes at infinite dilution presented the ratio 1.5 between alkyl chains again. However, apparent molar volumes upon micellization for sodium perfluoroheptanoate indicated a different aggregation pattern.

  18. Ultrasound-driven secondary self-assembly of amphiphilic β-cyclodextrin dimers.

    Science.gov (United States)

    Zhang, Hai-tao; Fan, Xiao-dong; Tian, Wei; Suo, Rong-tian; Yang, Zhen; Bai, Yang; Zhang, Wan-bin

    2015-03-23

    The controlled secondary self-assembly of amphiphilic molecules in solution is theoretically and practically significant in amphiphilic molecular applications. An amphiphilic β-cyclodextrin (β-CD) dimer, namely LA-(CD)2 , has been synthesized, wherein one lithocholic acid (LA) unit is hydrophobic and two β-CD units are hydrophilic. In an aqueous solution at room temperature, LA-(CD)2 self-assembles into spherical micelles without ultrasonication. The primary micelles dissociates and then secondarily form self-assemblies with branched structures under ultrasonication. The branched aggregates revert to primary micelles at high temperature. The ultrasound-driven secondary self-assembly is confirmed by transmission electron microscopy, dynamic light scattering, (1) H NMR spectroscopy, and Cu(2+) -responsive experiments. Furthermore, 2D NOESY NMR and UV/Vis spectroscopy results indicate that the formation of the primary micelles is driven by hydrophilic-hydrophobic interactions, whereas host-guest interactions promote the formation of the secondary assemblies. Additionally, ultrasonication is shown to be able to effectively destroy the primary hydrophilic-hydrophobic balances while enhancing the host-guest interaction between the LA and β-CD moieties at room temperature. PMID:25581876

  19. Self-Assembly of Discrete Metal Complexes in Aqueous Solution via Block Copolypeptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Timothy J. Deming

    2013-01-01

    Full Text Available The integration of discrete metal complexes has been attracting significant interest due to the potential of these materials for soft metal-metal interactions and supramolecular assembly. Additionally, block copolypeptide amphiphiles have been investigated concerning their capacity for self-assembly into structures such as nanoparticles, nanosheets and nanofibers. In this study, we combined these two concepts by investigating the self-assembly of discrete metal complexes in aqueous solution using block copolypeptides. Normally, discrete metal complexes such as [Au(CN2]−, when molecularly dispersed in water, cannot interact with one another. Our results demonstrated, however, that the addition of block copolypeptide amphiphiles such as K183L19 to [Au(CN2]− solutions induced one-dimensional integration of the discrete metal complex, resulting in photoluminescence originating from multinuclear complexes with metal-metal interactions. Transmission electron microscopy (TEM showed a fibrous nanostructure with lengths and widths of approximately 100 and 20 nm, respectively, which grew to form advanced nanoarchitectures, including those resembling the weave patterns of Waraji (traditional Japanese straw sandals. This concept of combining block copolypeptide amphiphiles with discrete coordination compounds allows the design of flexible and functional supramolecular coordination systems in water.

  20. Bioinspired amphiphilic phosphate block copolymers as non-fluoride materials to prevent dental erosion.

    Science.gov (United States)

    Lei, Yanda; Wang, Tongxin; Mitchell, James W; Zaidel, Lynette; Qiu, Jianhong; Kilpatrick-Liverman, LaTonya

    2014-01-01

    Inspired by the fact that certain natural proteins, e.g. casein phosphopeptide or amelogenin, are able to prevent tooth erosion (mineral loss) and to enhance tooth remineralization, a synthetic amphiphilic diblock copolymer, containing a hydrophilic methacryloyloxyethyl phosphate block (MOEP) and a hydrophobic methyl methacrylate block (MMA), was designed as a novel non-fluoride agent to prevent tooth erosion under acidic conditions. The structure of the polymer, synthesized by reversible addition-fragment transfer (RAFT) polymerization, was confirmed by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). While the hydrophilic PMOEP block within the amphiphilic block copolymer strongly binds to the enamel surface, the PMMA block forms a hydrophobic shell to prevent acid attack on tooth enamel, thus preventing/reducing acid erosion. The polymer treatment not only effectively decreased the mineral loss of hydroxyapatite (HAP) by 36-46% compared to the untreated control, but also protected the surface morphology of the enamel specimen following exposure to acid. Additionally, experimental results confirmed that low pH values and high polymer concentrations facilitate polymer binding. Thus, the preliminary data suggests that this new amphiphilic diblock copolymer has the potential to be used as a non-fluoride ingredient for mouth-rinse or toothpaste to prevent/reduce tooth erosion. PMID:25419457

  1. Intrinsically disordered amphiphilic peptides as potential targets in drug delivery vehicles.

    Science.gov (United States)

    Vincenzi, Marian; Accardo, Antonella; Costantini, Susan; Scala, Stefania; Portella, Luigi; Trotta, Annamaria; Ronga, Luisa; Guillon, Jean; Leone, Marilisa; Colonna, Giovanni; Rossi, Filomena; Tesauro, Diego

    2015-11-01

    Intrinsically disordered proteins/peptides play a crucial role in many physiological and pathological events and may assume a precise conformation upon binding to a specific target. Recently, we have described the conformational and functional properties of two linear ester peptides provided with the following sequences: Y-G-E-C-P-C-K-OAllyl (PepK) and Y-G-E-C-P-C-E-OAllyl (PepE). Both peptides are characterized by the presence of the "CPC" motif together with a few amino acids able to promote disorder. The CPC sequence is a binding motif for the CXCR4 receptor that represents a well-known target for cancer therapies. In this paper, we report on synthetic amphiphilic peptides that consist of lipophilic derivatives of PepE and PepK bearing two stearic alkyl chains and/or an ethoxylic spacer. These peptide amphiphiles form stable supramolecular aggregates; they present conformational features that are typical of intrinsically disordered molecules as shown by CD spectroscopy. Solution fluorescence and DLS studies have been performed to evaluate Critical Micellar Concentrations and the dimension of supramolecular aggregates. Moreover, preliminary in vitro cell-based assays have been conducted to investigate the molecular recognition processes involving the CXCR4 receptor. In the end, the results obtained have been compared with the previous data generated by the corresponding non-amphiphilic peptides (PepE and PepK). PMID:26263446

  2. New Amphiphilic Polypyridyl Ruthenium(Ⅱ) Sensitizer and Its Application in Dye-Sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    KONG Fan-Tai; DAI Song-Yuan; WANG Kong-Jia

    2007-01-01

    Amphiphilic polypyridyl ruthenium(Ⅱ) complex cis-di(isothiocyanato)(4,4'-di-tert-butyl-2,2'-bipyridyl)(4,4'-dicarboxy-2,2'-bipyridyl)ruthenium(Ⅱ) (K005) has been synthesized and characterized by cyclic voltammetry, 1H NMR, UV-Vis, and FT-IR spectroscopies. The sensitizer sensitizes TiO2 over a notably broad spectral range due to its intense metal-to-ligand charge-transfer (MLCT) bands at 537 and 418 nm. The photophysical and photochemical studies of K005 were contrasted with those of cis-Ru(dcbpy)2(NCS)2, known as the N3 dye, and the amphiphilic ruthenium(Ⅱ) dye Z907. A reversible couple at E1/2=0.725 V vs. saturated calomel electrode (SCE) with a separation of 0.08 V between the anodic and cathodic peaks, was observed due to the RuⅡ/Ⅲ couple by cyclic voltammetry.Furthermore, this amphiphilic ruthenium complex was successfully used as sensitizers for dye-sensitized solar cells with the efficiency of 3.72% at the 100 mW·cm-2 irradiance of air mass 1.5 simulated sunlight without optimization of TiO2 films and the electrolyte.

  3. CONTROLLED SYNTHESIS OF AMPHIPHILIC BLOCK POLYMERS HAVING GLUCOSE RESIDUES AND THEIR STRUCTURE FORMATION

    Institute of Scientific and Technical Information of China (English)

    Takeaki Miyamoto; Masahiko Minoda; Yoshinobu Tsujii

    1999-01-01

    Vinyl ether (VE)-based amphiphilic block copolymers with D-glucose residues as hydrophilic pendants were synthesized by CH3CH(OiBu)Cl/ZnI2-initiated sequential living cationic copolymerization of 3-O-(vinyloxy)ethyl-1, 2:5, 6-di-O-isopropylidene-D-glucofuranose (IGVE) and isobutyl VE (IBVE) and subsequent deprotection. The precursor block copolymers had a narrow molecular weight distribution(Mw/Mn~1.1) and a controlled segmental composition. The solubility characteristics of the amphiphilic copolymer depended strongly on composition. Their solvent-cast thin films were examined, under a transmission electron microscope, and could be seen to exhibit various microphase-separated surface morphologies such as spheres, cylinders, and lamellae, depending on composition. The amphiphilic copolymers with the appropriate segmental composition were found to form a stable monolayer at the airwater interface, which was successfully transferred onto a substrate by the Langmuir-Blodgett (LB)technique. The layered structure of the built-up LB films was controlled by blending the homopolymer.

  4. A Phytic Acid Induced Super-Amphiphilic Multifunctional 3D Graphene-Based Foam.

    Science.gov (United States)

    Song, Xinhong; Chen, Yiying; Rong, Mingcong; Xie, Zhaoxiong; Zhao, Tingting; Wang, Yiru; Chen, Xi; Wolfbeis, Otto S

    2016-03-14

    Surfaces with super-amphiphilicity have attracted tremendous interest for fundamental and applied research owing to their special affinity to both oil and water. It is generally believed that 3D graphenes are monoliths with strongly hydrophobic surfaces. Herein, we demonstrate the preparation of a 3D super-amphiphilic (that is, highly hydrophilic and oleophilic) graphene-based assembly in a single-step using phytic acid acting as both a gelator and as a dopant. The product shows both hydrophilic and oleophilic intelligence, and this overcomes the drawbacks of presently known hydrophobic 3D graphene assemblies. It can absorb water and oils alike. The utility of the new material was demonstrated by designing a heterogeneous catalytic system through incorporation of a zeolite into its amphiphilic 3D scaffold. The resulting bulk network was shown to enable efficient epoxidation of alkenes without prior addition of a co-solvent or stirring. This catalyst also can be recovered and re-used, thereby providing a clean catalytic process with simplified work-up. PMID:26890034

  5. The search for new amphiphiles: synthesis of a modular, high-throughput library

    Directory of Open Access Journals (Sweden)

    George C. Feast

    2014-07-01

    Full Text Available Amphiphilic compounds are used in a variety of applications due to their lyotropic liquid-crystalline phase formation, however only a limited number of compounds, in a potentially limitless field, are currently in use. A library of organic amphiphilic compounds was synthesised consisting of glucose, galactose, lactose, xylose and mannose head groups and double and triple-chain hydrophobic tails. A modular, high-throughput approach was developed, whereby head and tail components were conjugated using the copper-catalysed azide–alkyne cycloaddition (CuAAC reaction. The tails were synthesised from two core alkyne-tethered intermediates, which were subsequently functionalised with hydrocarbon chains varying in length and degree of unsaturation and branching, while the five sugar head groups were selected with ranging substitution patterns and anomeric linkages. A library of 80 amphiphiles was subsequently produced, using a 24-vial array, with the majority formed in very good to excellent yields. A preliminary assessment of the liquid-crystalline phase behaviour is also presented.

  6. Intrinsically disordered amphiphilic peptides as potential targets in drug delivery vehicles.

    Science.gov (United States)

    Vincenzi, Marian; Accardo, Antonella; Costantini, Susan; Scala, Stefania; Portella, Luigi; Trotta, Annamaria; Ronga, Luisa; Guillon, Jean; Leone, Marilisa; Colonna, Giovanni; Rossi, Filomena; Tesauro, Diego

    2015-11-01

    Intrinsically disordered proteins/peptides play a crucial role in many physiological and pathological events and may assume a precise conformation upon binding to a specific target. Recently, we have described the conformational and functional properties of two linear ester peptides provided with the following sequences: Y-G-E-C-P-C-K-OAllyl (PepK) and Y-G-E-C-P-C-E-OAllyl (PepE). Both peptides are characterized by the presence of the "CPC" motif together with a few amino acids able to promote disorder. The CPC sequence is a binding motif for the CXCR4 receptor that represents a well-known target for cancer therapies. In this paper, we report on synthetic amphiphilic peptides that consist of lipophilic derivatives of PepE and PepK bearing two stearic alkyl chains and/or an ethoxylic spacer. These peptide amphiphiles form stable supramolecular aggregates; they present conformational features that are typical of intrinsically disordered molecules as shown by CD spectroscopy. Solution fluorescence and DLS studies have been performed to evaluate Critical Micellar Concentrations and the dimension of supramolecular aggregates. Moreover, preliminary in vitro cell-based assays have been conducted to investigate the molecular recognition processes involving the CXCR4 receptor. In the end, the results obtained have been compared with the previous data generated by the corresponding non-amphiphilic peptides (PepE and PepK).

  7. Peptide-based gemini amphiphiles: phase behavior and rheology of wormlike micelles.

    Science.gov (United States)

    Shrestha, Rekha Goswami; Nomura, Kazuyuki; Yamamoto, Masashi; Yamawaki, Yukio; Tamura, Yoshinaga; Sakai, Kenichi; Sakamoto, Kazutami; Sakai, Hideki; Abe, Masahiko

    2012-11-01

    Aqueous binary phase behavior of a peptide-based gemini amphiphile with glutamic acid and lysine as spacer group, acylglutamyllysilacylglutamate (m-GLG-m where m = 12, 14, and 16), has been reported over a wide range of concentration and temperature. Lauroylglutamyllysillauroylglutamate, 12-GLG-12, self-assembles into spherical micelles above critical micelle concentration (CMC). The micellar region extends up to 32 wt %, and an ordering of spherical micelles into micellar cubic phase, I(1), takes place at 33 wt % at 25 °C. The phase transition, I(1) - hexagonal liquid crystal, (H(1)) - lamellar liquid crystal, (L(α)) has been observed with further increase in concentration; moreover, mixed phases are also observed between the pure liquid crystal domains. Similar phases were observed with 16-GLG-16 above 50 °C (Krafft temperature). The partial ternary phase behavior shows that the micellar solutions of m-GLG-m can solubilize a large amount of cationic amphiphile, alkyltrimethylammonium bromide, C(n)TAB, (where n = 14 (TTAB) and 16 (CTAB)) at 25 °C. An addition of C(n)TAB to the aqueous solutions of 16-GLG-16 in a dilute region forms a transparent solution of viscoelastic wormlike micelles at very low concentration (0.25 wt %) even at ambient condition. A mixture of oppositely charged amphiphiles, m-GLG-m and C(n)TAB, exhibits synergism as a result the amphiphile layer curvature, becomes less positive, and favors the transition from sphere to rod to transient networks (wormlike micelles). The gemini amphiphile, 16-GLG-16, forms wormlike micelles at relatively low concentrations compared to others reported so far. Viscosity increases by six orders of magnitude compared to that of pure solvent. The hydrophobic chain length of m-GLG-m and coamphiphile affects the rheology; the maximum viscosity achieved with 16-GLG-16/H(2)O/CTAB is higher than that of 14-GLG-14/H(2)O/CTAB, 12-GLG-12/H(2)O/CTAB, and 16-GLG-16/H(2)O/TTAB systems. These temperature-sensitive systems

  8. THE COMPATIBILITY OF BLENDS OF POLY(VINYL CHLORIDE) OR CHLORINATED POLY(VINYL CHLORIDE) WITH POLY(METHYL METHACRYLATE)

    Institute of Scientific and Technical Information of China (English)

    WANG Qingguo; CHENG Rongshi

    1988-01-01

    IR spectral shifts of carbonyl vibrational absorption for ethyl acetate, which acts analogically as the structural unit of poly(methyl methacrylate), in cyclohexane, chloroform, chlorinated paraffins, poly(vinyl chloride) and chlorinated poly(vinyl chloride) were measured. The results suggest that there are specific interactions between the carbonyl groups and the chlorinated hydrocarbons which could be responsible for the apparent compatibility of poly(vinyl chloride) -poly(methyl methacrylate) and chlorinated poly(vinyl chloride) -poly(methyl methacrylate) blends. Additionally, the effects of the preparation mode of blend films on phase separation and observed compatibility are discussed.

  9. Enhanced Germicidal Efficacy by Co-Delivery of Validamycin and Hexaconazole with Methoxy Poly(ethylene glycol)-Poly(lactide-co-glycolide) Nanoparticles.

    Science.gov (United States)

    Zhang, Jiakun; Liu, Yajing; Zhao, Caiyan; Cao, Lidong; Huang, Qiliang; Wu, Yan

    2016-01-01

    Co-delivery system has been proposed in pharmaceutical field aim to synergistic treatments. The combination formulation is also important in traditional pesticides formulations based on the low pest resistance risk and wide fungicidal spectrum. However, co-delivery nanoparticles (NPs) tend to be more environmentally friendly for the sustained-release behaviour and none of toxic organic solvents or dusts. Hence, we constructed co-delivery NPs which could delivery two kinds of pesticides, which function was similar with pesticides combination formulation. The co-delivery NPs of validamycin and hexaconazole were prepared with the amphiphilic copolymer methoxy poly(ethylene glycol)- poly(lactide-co-glycolide) (mPEG-PLGA) used an improved double emulsion method. The chemical structure of mPEG-PLGA copolymer was confirmed using fourier transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance spectroscopy (NMR). The co-delivery NPs all exhibited good size distribution and held sustained-release property. Germicidal efficacy of the co-delivery NPs against Rhizoctonia cerealis was also studied. The germicidal efficacy of co-delivery NPs against Rhizoctonia cerealis was better than that of traditional pesticides formulation. In addition, co-delivery NPs showed a lasting impact against Rhizoctonia cerealis. PMID:27398440

  10. Controlled release of 9-nitro-20(S)-camptothecin from methoxy poly(ethylene glycol)-poly(D,L-lactide) micelles

    Energy Technology Data Exchange (ETDEWEB)

    Gao, J M [College of Material Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Ming, J [Department of Medicament, The Second People' s Hospital of Sichuan, Chengdu 610041 (China); He, B; Gu, Z W; Zhang, X D [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064 (China)], E-mail: zwgu@scu.edu.cn

    2008-03-01

    9-nitro-20(S)-camptothecin (9-NC) is a potent topoisomerase-I inhibitor, and it was applied for clinical trials in cancer treatment. However, the applications of 9-NC were limited by its poor solubility and instability. In order to overcome these disadvantages, 9-NC was encapsulated in amphiphilic copolymer micelles composed of methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (mPEG-PDLLA, PELA). Three diblock copolymers with different PDLLA chain lengths were synthesized. The critical micelle concentration was varied from 10{sup -4} g L{sup -1} to 10{sup -2} g L{sup -1}. The 9-NC loaded micelles were nanospheres with diameters ranging from 30 nm to 60 nm. The relationship between the composition of copolymers and the drug loading content was discussed. The encapsulation of micelles improved the solubility of 9-NC greatly. The solubility of 9-NC in micelle M1 was about 250 times higher than that of 9-NC in a phosphate buffer solution (PBS). The stability of 9-NC in micelles was also promoted. After being incubated in PBS for 160 min, 80% of 9-NC in micelles existed as an active lactone form, while 85% of 9-NC in PBS were transferred to an inactive carboxylate salt form. The release experiments were carried out in PBS and the results showed that the release processes were controllable.

  11. Tailor-made starch-based conjugates containing well-defined poly(vinyl acetate and its derivative poly(vinyl alcohol

    Directory of Open Access Journals (Sweden)

    2011-06-01

    Full Text Available Reversible addition-fragmentation chain transfer (RAFT polymerization was adopted to synthesize starch-based conjugates that possessed controllable architecture and properties. Starch-based xanthate agent was prepared and applied as chain transfer agent to conduct the living/controlled polymerization (LCP of vinyl acetate, which generated tailor-made conjugates of starch and well-defined poly(vinyl acetate (SVAc. The relevant derivatives, conjugates of starch and chain length-controlled poly(vinyl alcohol (SVA, were obtained subsequently. Various characterizations such as Fourier transform infrared spectra (FTIR, ultraviolet-visible spectroscopy (UV, proton nuclear magnetic resonance (1H NMR, gel permeation chromatography (GPC, X-ray diffraction (XRD, Thermogravimetric analysis (TGA, and dynamic mechanical thermal analysis (DMTA were performed to examine the structure of intermediates and the starch-based conjugates. Static contact angle measurements revealed that the hydrophilic character of starch-based conjugates was tunable. Well-defined SVAc was amphiphilic and it was able to self-assemble into size controllable micelles, which was verified by contact angles, transmission electron microscopy (TEM and dynamic light scattering (DLS tests. SVA exhibited much higher capability to form physically cross-linked hydrogel than starch did. Both the characteristic of SVAc and SVA were chain length-dependent.

  12. Nanoporous nonwoven fibril-like morphology by cooperative self-assembly of poly(ethylene oxide)-block-poly(ethyl acrylate)-block-polystyrene and phenolic resin.

    Science.gov (United States)

    Deng, Guodong; Qiang, Zhe; Lecorchick, Willis; Cavicchi, Kevin A; Vogt, Bryan D

    2014-03-11

    Cooperative self-assembly of block copolymers with (in)organic precursors effectively generates ordered nanoporous films, but the porosity is typically limited by the need for a continuous (in)organic phase. Here, a network of homogeneous fibrous nanostructures (≈20 nm diameter cylinders) having high porosity (≈ 60%) is fabricated by cooperative self-assembly of a phenolic resin oligomer (resol) with a novel, nonfrustrated, ABC amphiphilic triblock copolymer template, poly(ethylene oxide)-block-poly(ethyl acrylate)-block-polystyrene (PEO-b-PEA-b-PS), via a thermally induced self-assembly process. Due to the high glass transition temperature (Tg) of the PS segments, the self-assembly behavior is kinetically hindered as a result of competing effects associated with the ordering of the self-assembled system and the cross-linking of resol that suppresses segmental mobility. The balance in these competing processes reproducibly yields a disordered fibril network with a uniform fibril diameter. This nonequilibrium morphology is dependent on the PEO-b-PEA-b-PS to resol ratio with an evolution from a relatively open fibrous structure to an apparent poorly ordered mixed lamellae-cylinder morphology. Pyrolysis of these former films at elevated temperatures yields a highly porous carbon film with the fibril morphology preserved through the carbonization process. These results illustrate a simple method to fabricate thin films and coatings with a well-defined fiber network that could be promising materials for energy and separation applications. PMID:24548298

  13. Role of β-hydroxybutyrate, its polymer poly-β-hydroxybutyrate and inorganic polyphosphate in mammalian health and disease

    Directory of Open Access Journals (Sweden)

    Elena N. Dedkova

    2014-07-01

    Full Text Available We provide a comprehensive review of the role of β-hydroxybutyrate (β-OHB, its linear polymer poly-β-hydroxybutyrate (PHB and inorganic polyphosphate (polyP in mammalian health and disease. β-OHB is a metabolic intermediate that constitutes 70% of ketone bodies produced during ketosis. Although ketosis has been generally considered as an unfavorable pathological state (e.g. diabetic ketoacidosis in type-1 diabetes mellitus, it has been suggested that induction of mild hyperketonemia may have certain therapeutic benefits. β-OHB is synthesized in the liver from acetyl-CoA by β-hydroxybutyrate dehydrogenase and can be used as alternative energy source. Elevated levels of PHB are associated with pathological states. In humans, short-chain, complexed PHB (cPHB is found in a wide variety of tissues and in atherosclerotic plaques. Plasma cPHB concentrations correlate strongly with atherogenic lipid profiles, and PHB tissue levels are elevated in type-1 diabetic animals. However, little is known about mechanisms of PHB action especially in the heart. In contrast to β-OHB, PHB is a water-insoluble, amphiphilic polymer that has high intrinsic viscosity and salt-solvating properties. cPHB can form non-specific ion channels in planar lipid bilayers and liposomes. PHB can form complexes with polyP and Ca2+ which increases membrane permeability. The biological roles played by polyP, a ubiquitous phosphate polymer with ATP-like bonds, have been most extensively studied in prokaryotes, however polyP has recently been linked to a variety of functions in mammalian cells, including blood coagulation, regulation of enzyme activity in cancer cells, cell proliferation, apoptosis and mitochondrial ion transport and energy metabolism. Recent evidence suggests that polyP is a potent activator of the mitochondrial permeability transition pore in cardiomyocytes and may represent a hitherto unrecognized key structural and functional component of the mitochondrial

  14. 手性两亲超支化嵌段共聚物PG-b-PBTQMO-b-PG的合成%Synthesis of chiral amphiphilic hyperbranched block copolymer PG-b-PBTQMO-b-PG

    Institute of Scientific and Technical Information of China (English)

    蒋伟伟; 李胜夏; 郭素珍; 胡志国

    2013-01-01

    以叠氮基修饰的超支化共聚物PG-b-PBAMO-b-PG和10,11-二氢化奎宁为原料,通过“click”化学反应合成了一种新型侧链含有奎宁的光学活性两亲超支化嵌段共聚物PG-b-PBTQMO-b-PG.用傅里叶转变红外光谱(FT-IR)和核磁共振氢谱(1HNMR)对产物结构和组成进行了表征,并利用圆二色谱法研究了手性共聚物的光学活性.%A new optically active amphiphilic hyperbranehed block copolymer bearing quinine pendants pol-yglyeerol-b-poly [3,3-bis(triazolyl-L-quinine) methyl oxetane]-b-polyglycerol (PG-b-PBTQMO-b-PG) was synthesized by" click" reaction of azido-modified polyglycerol-b-poly(3,3-bis(azidomethyl) oxetane)-b-polyglycerol (PG-b-PBAMO-b-PG) hyperbranched eopolymer and 10,11-didehydro quinine.The Fourier transform infrared spectrum(FT-IR) and 1H nuclear magnetic resonance spectroscopy(1HNMR)were used to confirm its structure and composition.Additionally,the solution properties of this chiral copolymer were stu-died by circular dichroism(CD) spectroscopy.

  15. Poly(ethylene oxide) surfactant polymers

    OpenAIRE

    VACHEETHASANEE, KATANCHALEE; WANG, SHUWU; QIU, YONGXING; Marchant, Roger E.

    2004-01-01

    We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly (ethyleneoxide) (PEO) were simultaneously att...

  16. Microbial production of natural poly amino acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Three kinds of poly amino acids, poly-γ-glutamic acid, poly(ε-L-lysine) and multi-L-arginyl-poly (L-aspartic acid) can be synthesized by enzymatic process independently from ribosomal protein biosynthesis pathways in microorganism. These biosynthesized polymers have attracted more and more attentions because of their unique properties and various applications. In this review, the current knowledge on the biosynthesis, biodegradations and applications of these three poly amino acids are summarized.

  17. Advanced poly-LED displays

    Science.gov (United States)

    Childs, Mark; Nisato, Giovanni; Fish, D.; Giraldo, Andrea; Jenkins, A. J.; Johnson, Mark T.

    2003-05-01

    Philips have been actively developing polymer OLED (poly-LED) displays as a future display technology. Their emissive nature leads to a very attractive visual appearance, with wide viewing angle, high brightness and fast response speed. Whilst the first generation of poly-LED displays are likely to be passive-matrix driven, power reduction and resolution increase will lead to the use of active-matrix poly-LED displays. Philips Research have designed, fabricated and characterized five different designs of active-matrix polymer-LED display. Each of the five displays makes use of a distinct pixel programming- or pixel drive-technique, including current programming, threshold voltage measurement and photodiode feedback. It will be shown that hte simplest voltage-programmed current-source pixel suffers from potentially unacceptable brightness non-uniformity, and that advanced pixel circuits can provide a solution to this. Optical-feedback pixel circuits will be discussed, showing that they can be used to improve uniformity and compensate for image burn-in due to polymer-LED material degradation, improving display lifetime. Philips research has also been active in developing technologies required to implement poly-LED displays on flexible substrates, including materials, processing and testing methods. The fabrication of flexible passive-matrix poly-LED displays will be presented, as well as the ongoing work to assess the suitability of processing flexible next-generation poly-LED displays.

  18. Construction of amphiphilic segments on polypropylene nonwoven surface and its application in removal of endocrine disrupting compounds (EDCs) from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kai [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); Wei, Junfu, E-mail: junfuwei1963@163.com [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); Zhou, Xiangyu [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); Liu, Nana [State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300160 (China); School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160 (China)

    2015-05-15

    Highlights: • The amphiphilic segments on polypropylene nonwoven surface were constructed successfully. • The adsorption behavior for EDCs of the amphiphilic adsorption materials was systematically studied. • The novel amphiphilic adsorption materials have broad application prospects in EDCs removal from aqueous solution. - Abstract: The amphiphilic segments on polypropylene nonwoven (PP nonwoven) surface were constructed using the ultraviolet (UV) irradiation graft polymerization for the removal of endocrine disrupting compounds (EDCs) with different polarity from aqueous solution. The stearyl acrylate (SA) as hydrophobic functional monomer was introduced onto the surface of PP nonwoven fabric at first stage and then the hydroxyethyl acrylate (HEA) as hydrophilic functional monomer was introduced subsequently. The effect of functional monomer concentration and UV irradiation time on grafting ratio was studied and discussed. The novel amphiphilic structure was designed and constructed based on adsorption capacity for the target micropollutants. The structure and composition of the amphiphilic adsorption materials were characterized by Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle (CA). The adsorption behaviors for EDCs of the amphiphilic adsorption materials were studied and the results indicated that the adsorption capacity and adsorption rate were superior to single SA grafted PP nonwoven (PP-g-SA) and single HEA grafted PP nonwoven (PP-g-HEA). The novel amphiphilic adsorption material was efficient for the removal of EDCs with different polarity and could be utilized as a potential adsorption material for removing EDCs from aqueous solution.

  19. Tipping the Scale from Disorder to Alpha-helix: Folding of Amphiphilic Peptides in the Presence of Macroscopic and Molecular Interfaces

    OpenAIRE

    Cahit Dalgicdir; Christoph Globisch; Christine Peter; Mehmet Sayar

    2015-01-01

    RESEARCH ARTICLE Tipping the Scale from Disorder to Alpha-helix: Folding of Amphiphilic Peptides in the Presence of Macroscopic and Molecular Interfaces Cahit Dalgicdir1, Christoph Globisch2, Christine Peter2*, Mehmet Sayar1* 1 College of Engineering, Koç University, Istanbul, Turkey, 2 Theoretical Chemistry, University of Konstanz, Konstanz, Germany * (CP); (MS) Abstract Secondary amphiphilicity is inherent to the...

  20. A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion

    Directory of Open Access Journals (Sweden)

    William Gibbons

    2013-04-01

    Full Text Available One of the concerns for economical production of ethanol from biomass is the large volume and high cost of the cellulolytic enzymes used to convert biomass into fermentable sugars. The presence of acetyl groups in hemicellulose and lignin in plant cell walls reduces accessibility of biomass to the enzymes and makes conversion a slow process. In addition to low enzyme accessibility, a rapid deactivation of cellulases during biomass hydrolysis can be another factor contributing to the low sugar recovery. As of now, the economical reduction in lignin content of the biomass is considered a bottleneck, and raises issues for several reasons. The presence of lignin in biomass reduces the swelling of cellulose fibrils and accessibility of enzyme to carbohydrate polymers. It also causes an irreversible adsorption of the cellulolytic enzymes that prevents effective enzyme activity and recycling. Amphiphiles, such as surfactants and proteins have been found to improve enzyme activity by several mechanisms of action that are not yet fully understood. Reduction in irreversible adsorption of enzyme to non-specific sites, reduction in viscosity of liquid and surface tension and consequently reduced contact of enzyme with air-liquid interface, and modifications in biomass chemical structure are some of the benefits derived from surface active molecules. Application of some of these amphiphiles could potentially reduce the capital and operating costs of bioethanol production by reducing fermentation time and the amount of enzyme used for saccharification of biomass. In this review article, the benefit of applying amphiphiles at various stages of ethanol production (i.e., pretreatment, hydrolysis and hydrolysis-fermentation is reviewed and the proposed mechanisms of actions are described.

  1. Structural transformation of peptide amphiphile self-assembly induced by headgroup charge and size regulation

    Science.gov (United States)

    Gao, Changrui; Bedzyk, Michael; Olvera, Monica; Kewalramani, Sumit; Palmer, Liam

    The ability to control the nano and the meso-scale architecture of molecular assemblies is one of the major challenges in nanoscience. Significantly, structural transformations of amphiphilic aggregates induced by variations in environmental conditions have attracted attention due to their biotechnological relevance. Here, we study the assembly in aqueous solution for a modular series of peptide amphiphiles with 3, 2 or 1 lysine groups conjugated to a C16 carbon tail (C16K3, C16K2 and C16K1) . This system design allow us to probe how the equilibrium structure of the self-assembly can be tuned by controlling the coupling between steric (via choice of headgroup: K3, K2, or K1) and electrostatic (via solution pH) interactions. Solution small- and wide-angle X-ray scattering (SAXS/WAXS) and transmission electron microscopy (TEM) studies reveal that depending on pH and number of lysines in the lipid headgroup, amphiphiles can assemble into a range of structures: spherical micelles, bilayer ribbons and vesicles. We also perform detailed phase space mapping of pH-and headgroup size dependency of the structures of assembly over 0.1-100 nm length scales via SAXS/WAXS. The experimental results in conjunction with molecular dynamics (MD) simulations deduce quantitative relations between pH-dependent molecular charges, steric constraints and self-assembly morphologies, which is significant for developing experimental routes to obtain assembly structures with specific nano- and meso-scale features through controlled external stimuli.

  2. Mobilization and biodegradation of 2-methylnaphthalene by amphiphilic polyurethane nano-particle.

    Science.gov (United States)

    Kim, Young-Bum; Kim, Ju-Young; Kim, Eun-ki

    2009-10-01

    Amphiphilic polyurethane (APU) nano-particle enhanced the mobilization of 2-methylnaphthalene (2-MNPT) in soil. Significant increase in the solubility of 2-MNPT was achieved. The molar solubilization ratio was 0.4 (mole 2-MNPT/mole APU). Simple precipitation of APU particle by 2 N CaCl(2) recovered 95% of APU particle and 92% of 2-MNPT simultaneously. Also, 2-MNPT, which was entrapped inside the APU particle, was directly degraded by Acinetobacter sp. as same efficiency as without APU particle. These results showed the potentials of APU particle in the mobilization and biodegradation of hydrophobic compounds from soil. PMID:19214790

  3. Lattice-Gas Simulations of Ternary Amphiphilic Fluid Flow in Porous Media

    CERN Document Server

    Coveney, P V; Wilson, J L; Fowler, P W; Al-Mushadani, O; Boghosian, B M

    1998-01-01

    We develop our existing two-dimensional lattice-gas model to simulate the flow of single-phase, binary-immiscible and ternary-amphiphilic fluids. This involves the inclusion of fixed obstacles on the lattice, together with the inclusion of ``no-slip'' boundary conditions. Here we report on preliminary applications of this model to the flow of such fluids within model porous media. We also construct fluid invasion boundary conditions, and the effects of invading aqueous solutions of surfactant on oil-saturated rock during imbibition and drainage are described.

  4. Plasmonic Vesicles of Amphiphilic Nanocrystals: Optically Active Multifunctional Platform for Cancer Diagnosis and Therapy.

    Science.gov (United States)

    Song, Jibin; Huang, Peng; Duan, Hongwei; Chen, Xiaoyuan

    2015-09-15

    Vesicular structures with compartmentalized, water-filled cavities, such as liposomes of natural and synthetic amphiphiles, have tremendous potential applications in nanomedicine. When block copolymers self-assemble, the result is polymersomes with tailored structural properties and built-in releasing mechanisms, controlled by stimuli-responsive polymer building blocks. More recently, chemists are becoming interested in multifunctional hybrid vesicles containing inorganic nanocrystals with unique optical, electronic, and magnetic properties. In this Account, we review our recent progress in assembling amphiphilic plasmonic nanostructures to create a new class of multifunctional hybrid vesicles and applying them towards cancer diagnosis and therapy. Localized surface plasmon resonance (LSPR) gives plasmonic nanomaterials a unique set of optical properties that are potentially useful for both biosensing and nanomedicine. For instance, the strong light scattering at their LSPR wavelength opens up the applications of plasmonic nanostructures in single particle plasmonic imaging. Their superior photothermal conversion properties, on the other hand, make them excellent transducers for photothermal ablation and contrast agents for photoacoustic imaging. Of particular note for ultrasensitive detection is that the confined electromagnetic field resulting from excitation of LSPR can give rise to highly efficient surface enhanced Raman scattering (SERS) for molecules in close proximity. We have explored several ways to combine well-defined plasmonic nanocrystals with amphiphilic polymer brushes of diverse chemical functionalities. In multiple systems, we have shown that the polymer grafts impart amphiphilicity-driven self-assembly to the hybrid nanoparticles. This has allowed us to synthesize well-defined vesicles in which we have embedded plasmonic nanocrystals in the shell of collapsed hydrophobic polymers. The hydrophilic brushes extend into external and interior aqueous

  5. Plasmonic Vesicles of Amphiphilic Nanocrystals: Optically Active Multifunctional Platform for Cancer Diagnosis and Therapy.

    Science.gov (United States)

    Song, Jibin; Huang, Peng; Duan, Hongwei; Chen, Xiaoyuan

    2015-09-15

    Vesicular structures with compartmentalized, water-filled cavities, such as liposomes of natural and synthetic amphiphiles, have tremendous potential applications in nanomedicine. When block copolymers self-assemble, the result is polymersomes with tailored structural properties and built-in releasing mechanisms, controlled by stimuli-responsive polymer building blocks. More recently, chemists are becoming interested in multifunctional hybrid vesicles containing inorganic nanocrystals with unique optical, electronic, and magnetic properties. In this Account, we review our recent progress in assembling amphiphilic plasmonic nanostructures to create a new class of multifunctional hybrid vesicles and applying them towards cancer diagnosis and therapy. Localized surface plasmon resonance (LSPR) gives plasmonic nanomaterials a unique set of optical properties that are potentially useful for both biosensing and nanomedicine. For instance, the strong light scattering at their LSPR wavelength opens up the applications of plasmonic nanostructures in single particle plasmonic imaging. Their superior photothermal conversion properties, on the other hand, make them excellent transducers for photothermal ablation and contrast agents for photoacoustic imaging. Of particular note for ultrasensitive detection is that the confined electromagnetic field resulting from excitation of LSPR can give rise to highly efficient surface enhanced Raman scattering (SERS) for molecules in close proximity. We have explored several ways to combine well-defined plasmonic nanocrystals with amphiphilic polymer brushes of diverse chemical functionalities. In multiple systems, we have shown that the polymer grafts impart amphiphilicity-driven self-assembly to the hybrid nanoparticles. This has allowed us to synthesize well-defined vesicles in which we have embedded plasmonic nanocrystals in the shell of collapsed hydrophobic polymers. The hydrophilic brushes extend into external and interior aqueous

  6. Control of structure and growth of polymorphic crystalline thin films of amphiphilic molecules on liquid surfaces

    DEFF Research Database (Denmark)

    Weinbach, S.P.; Kjær, K.; Bouwman, W.G.;

    1994-01-01

    The spontaneous formation and coexistence of crystalline polymorphic trilayer domains in amphiphilic films at air-liquid interfaces is demonstrated by grazing incidence synchrotron x-ray diffraction. These polymorphic crystallites may serve as models for the early stages of crystal nucleation and...... growth, helping to elucidate the manner in which additives influence the progress of crystal nucleation, growth, and polymorphism and suggesting ways of selectively generating and controlling multilayers on liquid surfaces. Auxiliary molecules have been designed to selectively inhibit development of the...

  7. Water-repellent textile via decorating fibers with amphiphilic Janus particles.

    Science.gov (United States)

    Synytska, Alla; Khanum, Rina; Ionov, Leonid; Cherif, Chokri; Bellmann, C

    2011-04-01

    We investigated morphology and wetting properties of textiles modified by chemically immobilized amphiphilic micrometer and submicrometer large Janus particles. The Janus particles bind by their reactive side to the textile surface, while their hydrophobic side faces the environment. It was found that the character of immobilization of the Janus particles on textile depends on their size: larger particles bind between fibers, while smaller ones bind to the fiber surface. In both cases, immobilization of Janus particles results in the hydrophobization of the hydrophilic textile surface. Finally, we demonstrated that submicrometer large Janus particles are very efficient for the design of water-repellent textiles. PMID:21366338

  8. Novel self-associative and multiphase nanostructured soft carriers based on amphiphilic hyaluronic acid derivatives

    DEFF Research Database (Denmark)

    Eenschooten, Corinne; Vaccaro, Andrea; Delie, Florence;

    2012-01-01

    The purpose of the present study was to investigate the physicochemical properties in aqueous media of amphiphilic hyaluronic acid (HA) derivatives obtained by reaction of HA’s hydroxyl groups with octenyl succinic anhydride (OSA). The self-associative properties of the resulting octenyl succinic...... anhydridemodified hyaluronic acid (OSA-HA) derivatives were studied by fluorescence spectroscopy using Nile Red as fluorophore. The morphology, size and surface charge of the OSA-HA assemblies were determined by transmission electron microscopy, dynamic light scattering and by measuring their electrophoretic...

  9. Synthesis, Characterization, Critical Micelle Concentration and Biological Activity of two-Headed Amphiphiles

    OpenAIRE

    Actis, Marcelo

    2008-01-01

    In this project, we synthesized a new homologous series of five long-chain, two-headed amphiphiles [2CAm13, 2CAm15, 2CAm17, 2CAm19, 2CAm21; CH3(CH2)n-1CONHC(CH3)(CH2CH2COOH)2, n = 13, 15, 17, 19, 21]. The synthesis of the 2CAmn series was accomplished in four steps. The first step involves a reaction of nitroethane and two equivalents of tert-butyl acrylate to create the nitrodiester synthon [O2NC(CH3)(CH2CH2COOtBu)2] by successive Michael additions. The second step in the synthesi...

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

    Science.gov (United States)

    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

  11. Mobilization and biodegradation of 2-methylnaphthalene by amphiphilic polyurethane nano-particle.

    Science.gov (United States)

    Kim, Young-Bum; Kim, Ju-Young; Kim, Eun-ki

    2009-10-01

    Amphiphilic polyurethane (APU) nano-particle enhanced the mobilization of 2-methylnaphthalene (2-MNPT) in soil. Significant increase in the solubility of 2-MNPT was achieved. The molar solubilization ratio was 0.4 (mole 2-MNPT/mole APU). Simple precipitation of APU particle by 2 N CaCl(2) recovered 95% of APU particle and 92% of 2-MNPT simultaneously. Also, 2-MNPT, which was entrapped inside the APU particle, was directly degraded by Acinetobacter sp. as same efficiency as without APU particle. These results showed the potentials of APU particle in the mobilization and biodegradation of hydrophobic compounds from soil.

  12. Poly(ethylene-co-acrylic acid)-g-poly(ethylene glycol) graft copolymer templated synthesis of mesoporous TiO{sub 2} thin films for quasi-solid-state dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Rajkumar; Jung, Ye Eun; Kim, Dong Jun; Kim, Sang Jin; Kim, Jong Hak, E-mail: jonghak@yonsei.ac.kr

    2014-02-03

    An amphiphilic graft copolymer, poly(ethylene-co-acrylic acid)-graft-poly(ethylene glycol) (PEAA-g-PEG), consisting of a PEAA backbone and PEG side chains was synthesized via an esterification reaction. {sup 1}H nuclear magnetic resonance and Fourier-transformed infrared analysis demonstrated esterification between carboxylic acid of PEAA and hydroxyl group of PEG. Small angle X-ray scattering results revealed that the crystalline domain spacing of PEAA increased from 11.3 to 12.8 nm upon using a more polar solvent with a higher affinity for poly(acrylic acid), while the crystalline domain spacing of PEAA disappeared with PEG grafting, indicating structural change to an amorphous state. Mesoporous TiO{sub 2} thin films were synthesized via a sol–gel reaction using PEAA-g-PEG graft copolymer as a structure-directing agent. The hydrophilically-preformed TiO{sub 2} nanoparticles were selectively confined in the hydrophilic PEG domains of the graft copolymer, and mesoporous TiO{sub 2} thin films were formed, as confirmed by scanning electron microscopy. The morphology of TiO{sub 2} films was tunable by varying the concentrations of polymer solutions and the amount of preformed TiO{sub 2}. A quasi-solid-state dye-sensitized solar cell fabricated with PEAA-g-PEG templated TiO{sub 2} film exhibited an energy conversion efficiency of 3.8% at 100 mW/cm{sup 2}, which was greater than that of commercially-available paste (2.6%) at a similar film thickness (3 μm). The improved performance was due to the larger surface area for high dye loading and organized structure with good interconnectivity. - Highlights: • Poly(ethylene-co-acrylic acid)-g-poly(ethylene glycol) (PEAA-g-PEG) graft copolymer is synthesized. • Amphiphilic PEAA-g-PEG acts as a structure directing agent. • Mesoporous TiO{sub 2} thin films are prepared by sol–gel reaction using PEAA-g-PEG template. • Efficiency of DSSC with templated TiO{sub 2} is greater than with commercial TiO{sub 2} paste.

  13. Poly(ethylene-co-acrylic acid)-g-poly(ethylene glycol) graft copolymer templated synthesis of mesoporous TiO2 thin films for quasi-solid-state dye sensitized solar cells

    International Nuclear Information System (INIS)

    An amphiphilic graft copolymer, poly(ethylene-co-acrylic acid)-graft-poly(ethylene glycol) (PEAA-g-PEG), consisting of a PEAA backbone and PEG side chains was synthesized via an esterification reaction. 1H nuclear magnetic resonance and Fourier-transformed infrared analysis demonstrated esterification between carboxylic acid of PEAA and hydroxyl group of PEG. Small angle X-ray scattering results revealed that the crystalline domain spacing of PEAA increased from 11.3 to 12.8 nm upon using a more polar solvent with a higher affinity for poly(acrylic acid), while the crystalline domain spacing of PEAA disappeared with PEG grafting, indicating structural change to an amorphous state. Mesoporous TiO2 thin films were synthesized via a sol–gel reaction using PEAA-g-PEG graft copolymer as a structure-directing agent. The hydrophilically-preformed TiO2 nanoparticles were selectively confined in the hydrophilic PEG domains of the graft copolymer, and mesoporous TiO2 thin films were formed, as confirmed by scanning electron microscopy. The morphology of TiO2 films was tunable by varying the concentrations of polymer solutions and the amount of preformed TiO2. A quasi-solid-state dye-sensitized solar cell fabricated with PEAA-g-PEG templated TiO2 film exhibited an energy conversion efficiency of 3.8% at 100 mW/cm2, which was greater than that of commercially-available paste (2.6%) at a similar film thickness (3 μm). The improved performance was due to the larger surface area for high dye loading and organized structure with good interconnectivity. - Highlights: • Poly(ethylene-co-acrylic acid)-g-poly(ethylene glycol) (PEAA-g-PEG) graft copolymer is synthesized. • Amphiphilic PEAA-g-PEG acts as a structure directing agent. • Mesoporous TiO2 thin films are prepared by sol–gel reaction using PEAA-g-PEG template. • Efficiency of DSSC with templated TiO2 is greater than with commercial TiO2 paste

  14. Research developments on amphiphilic hyperbranched polymers%两亲性超支化聚合物研究进展

    Institute of Scientific and Technical Information of China (English)

    强涛涛; 张国国; 王学川

    2013-01-01

    In this paper, the research progress in amphiphilic hyperbranched polymers is overviewed. Synthetic methods of amphiphilic hyperbranched polymers are introduced, which covers the modification of end groups of the hyperbranched polymers with long chain alkyl and polyethylene glycol, and the polymerization of vinyl derivatives through free radical polymerization or ring-opening polymerization, using hyperbranched polymers as macroinitiator. Different structures of amphiphilic hyperbranched polymers have their unique properties in solution, such as core-shell unimolecule micelles and different micellar conformation aggregates. Moreover, the application of amphiphilic hyperbranched polymers, such as drug delivery carrier, material modification, and the encapsulation of dye molecules is also introduced. Then, the development trend of amphiphilic hyperbranched polymers is proposed. The preparation of special properties of amphiphilic hyperbranched polymers and the application of amphiphilic hyperbranched polymers in biological medicine should be the main focus in the development of amphiphilic hyperbranched polymers.%介绍了两亲性超支化聚合物的合成方法,利用长链烷基和聚乙二醇对超支化聚合物端基接枝改性;或者对超支化聚合物改性引入活性位点,再利用其引发乙烯基单体,通过自由基聚合、开环聚合得到两亲性超支化聚合物.阐述了不同结构的两亲性超支化聚合物在溶液中的独特性质,如核壳型单分子胶束以及不同胶束形态的聚集体.详细介绍了两亲性超支化聚合物在药物输送载体、材料改性以及染料分子的封装等领域的应用现状,指出采用新的改性技术、聚合技术制备具有特殊性能的两亲性超支化聚合物以及探索其在生物医药领域的研究为今后的主要发展方向.

  15. NMR investigations of the conformation of new cyclodextrin-based amphiphilic transporters for hydrophobic drugs: molecular lollipops

    Science.gov (United States)

    Bellanger, Nathalie; Perly, Bruno

    1992-10-01

    Amphiphilic compounds, obtained by grafting aliphatic acids onto a modified cyclodextrin, have been synthesized and studied by solution NMR. The large chain-length dependence of the NMR spectra in aqueous media is explained by the possible formation of auto-inclusion complexes. This process has been evidenced by extensive NMR experiments and by competition with potential guests. This new class of molecules ("lollipops") provides important information for the optimization of a design for amphiphilic transporters to be included in organized phases such as micelles or liposomes.

  16. Surface and thermomechanical characterization of polyurethane networks based on poly(dimethylsiloxane and hyperbranched polyester

    Directory of Open Access Journals (Sweden)

    M. V. Pergal

    2013-10-01

    Full Text Available Two series of polyurethane (PU networks based on Boltorn® hyperbranched polyester (HBP and hydroxyethoxy propyl terminated poly(dimethylsiloxane (EO-PDMS or hydroxy propyl terminated poly(dimethylsiloxane (HPPDMS, were synthesized. The effect of the type of soft PDMS segment on the properties of PUs was investigated by Fourier transform infrared spectroscopy (FTIR, contact angle measurements, surface free energy determination, X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM, atomic force microscopy (AFM, dynamic mechanical thermal analysis (DMTA and differential scanning calorimetry (DSC. The surface characterization of PUs showed existence of slightly amphiphilic character and it revealed that PUs based on HP-PDMS have lower surface free energy, more hydrophobic surface and better waterproof performances than PUs based on EO-PDMS. PUs based on HPPDMS had higher crosslinking density than PUs based on EO-PDMS. DSC and DMTA results revealed that these newlysynthesized PUs exhibit the glass transition temperatures of the soft and hard segments. DMTA, SEM and AFM results confirmed existence of microphase separated morphology. The results obtained in this work indicate that PU networks based on HBP and PDMS have improved surface and thermomechanical properties.

  17. A designed amphiphilic peptide containing the silk fibroin motif as a potential carrier of hydrophobic drugs

    Institute of Scientific and Technical Information of China (English)

    Qinghan Zhou; Juan Lin; Jing Wang; Feng Li; Fushan Tang; Xiaojun Zhao

    2009-01-01

    The amphiphilic peptide is becoming attractive as a potential drug carder to improve the dissolvability of hydrophobic drugs in an aqueous system; thus, facilitating drug uptake by target cells. Here, we report a novel designed amphiphilic peptide, Ac-RADAGAGA-RADAGAGA-NH_2, which was able to stabilize pyrene, a hydrophobic model drug we chose to study in aqueous solution. This designed peptide formed a colloidal suspension by encapsulating pyrene inside the peptide-pyrene complex. Egg phosphatidylcholine (EPC) ves-icles were used to mimic cell bilayer membranes. We found that pyrene was released from the peptide coating into the EPC vesicles by mixing the colloidal suspension with EPC vesicles, which was followed by steady fluorescence spectra as a function of time. A calibration curve for the amount of pyrene released into the EPC vesicles at a given time was used to determine the final concentration of pyrene released into the lipid vesicles from the peptide-pyrene complex. The release rate of the peptide pyrene complex was calculated to quan-tify the transfer of pyrene into EPC vesicles.

  18. Comparison of facially amphiphilic versus segregated monomers in the design of antibacterial copolymers.

    Science.gov (United States)

    Gabriel, Gregory J; Maegerlein, Janet A; Nelson, Christopher F; Dabkowski, Jeffrey M; Eren, Tarik; Nüsslein, Klaus; Tew, Gregory N

    2009-01-01

    A direct comparison of two strategies for designing antimicrobial polymers is presented. Previously, we published several reports on the use of facially amphiphilic (FA) monomers which led to polynorbornenes with excellent antimicrobial activities and selectivities. Our polymers obtained by copolymerization of structurally similar segregated monomers, in which cationic and non-polar moieties reside on separate repeat units, led to polymers with less pronounced activities. A wide range of polymer amphiphilicities was surveyed by pairing a cationic oxanorbornene with eleven different non-polar monomers and varying the comonomer feed ratios. Their properties were tested using antimicrobial assays and copolymers possessing intermediate hydrophobicities were the most active. Polymer-induced leakage of dye-filled liposomes and microscopy of polymer-treated bacteria support a membrane-based mode of action. From these results there appears to be profound differences in how a polymer made from FA monomers interacts with the phospholipid bilayer compared with copolymers from segregated monomers. We conclude that a well-defined spatial relationship of the whole polymer is crucial to obtain synthetic mimics of antimicrobial peptides (SMAMPs): charged and non-polar moieties need to be balanced locally, for example, at the monomer level, and not just globally. We advocate the use of FA monomers for better control of biological properties. It is expected that this principle will be usefully applied to other backbones such as the polyacrylates, polystyrenes, and non-natural polyamides. PMID:19021176

  19. Progress in developing amphiphilic cyclodextrin-based nanodevices for drug delivery.

    Science.gov (United States)

    Yaméogo, Josias B G; Géze, Annabelle; Choisnard, Luc; Putaux, Jean-Luc; Semdé, Rasmané; Wouessidjewe, Denis

    2014-01-01

    Nowadays, colloidal drug carriers represent an alternative to solve drug bioavailabily problems. During the past two decades, colloidal drug carriers have proved to improve the therapeutic index of drugs and thus increase their efficacy and/or reduce their toxicity. However, the major challenge in the development of these drug carriers remains the search for materials able to self-organize into stable nanoscale systems. In particular, amphiphilic α-, β- and γ-cyclodextrins (CDs), grafted on their secondary or primary side with different aliphatic chains, have been investigated as drug delivery vehicles due to their ability to self-assemble and form various stable colloidal systems such as micellar aggregates, nanoreservoirs or nanoparticles exhibiting a matricial, multilamellar or hexagonal supramolecular organization. These self-assembled CD-based nanodevices show some advantages in terms of stability, good ability to associate lipophilic drugs and good in vivo tolerance. This review focuses on the potential of the structured nanoparticles obtained from nonionic amphiphilic CDs in drug delivery and targeting. We discuss the synthesis and characterization of the building blocks as well as the preparation and characterization of colloidal particles made from these materials. We also considered some pharmaceutical applications and identified opportunities for an optimum use of this CD-based nanotechnology approach in addressing worldwide priority health problems. PMID:24354667

  20. Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene

    Directory of Open Access Journals (Sweden)

    Ludmilla Lumholdt

    2014-11-01

    Full Text Available Polypropylene nonwovens were functionalised using a self-assembled, amphiphilic cyclodextrin coating and the potential for water purification by removal of pollutants was studied. As benzene is one of the problematic compounds in the Water Framework Directive, six volatile organic compounds (benzene and five benzene-based substances were chosen as model compounds. The compounds were tested as a mixture in order to provide a more realistic situation since the wastewater will be a complex mixture containing multiple pollutants. The volatile organic compounds are known to form stable inclusion complexes with cyclodextrins. Six different amphiphilic cyclodextrin derivatives were synthesised in order to elucidate whether or not the uptake abilities of the coating depend on the structure of the derivative. Headspace gas chromatography was used for quantification of the uptake exploiting the volatile nature of benzene and its derivatives. The capacity was shown to increase beyond the expected stoichiometries of guest–host complexes with ratios of up to 16:1.

  1. Synthesis of an amphiphilic rhodamine derivative and characterization of its solution and thin film properties

    Energy Technology Data Exchange (ETDEWEB)

    Aviv, Hagit [Department of Chemistry, Bar-Ilan University, Ramat-Gan (Israel); Bar-Ilan University Institute for Nanotechnology and Advanced Materials, Ramat-Gan (Israel); Harazi, Sivan [Department of Chemistry, Bar-Ilan University, Ramat-Gan (Israel); Department of Physics, Bar-Ilan University, Ramat-Gan (Israel); Bar-Ilan University Institute for Nanotechnology and Advanced Materials, Ramat-Gan (Israel); Schiff, Dillon [Department of Chemistry, Bar-Ilan University, Ramat-Gan (Israel); Bar-Ilan University Institute for Nanotechnology and Advanced Materials, Ramat-Gan (Israel); Ramon, Yoni [Department of Chemistry, Bar-Ilan University, Ramat-Gan (Israel); Department of Physics, Bar-Ilan University, Ramat-Gan (Israel); Bar-Ilan University Institute for Nanotechnology and Advanced Materials, Ramat-Gan (Israel); Tischler, Yaakov R., E-mail: yrt@biu.ac.il [Department of Chemistry, Bar-Ilan University, Ramat-Gan (Israel); Bar-Ilan University Institute for Nanotechnology and Advanced Materials, Ramat-Gan (Israel)

    2014-08-01

    Here we present characterization of solution and thin film properties of Lissamine rhodamine B sulfonyl didodecyl amine (LRSD), an amphiphilic derivative of rhodamine. LRSD was synthesized by functionalizing Lissamine rhodamine B sulfonyl chloride (LRSC) with didodecylamine via a straightforward sulfonylation reaction. LRSD's long alkane chains make it highly soluble in chloroform, with a marked increase in brightness compared to the starting material. LRSD is shown to form well-defined robust micelles in water, without the addition of a co-surfactant and stable monolayers at the air–water interface. The greater lipophilicity of LRSD also enables doping into non-polar polymeric host matrices such as polystyrene with less aggregation and hence higher fluorescence quantum yield than LRSC or even rhodamine B. The monolayers of LRSD were prepared via Langmuir–Blodgett deposition and showed shifts in the photoluminescence peak from 575 nm to 595 nm, as the surface pressure is varied from 3 mN/m to 11 mN/m. - Highlights: • Lissamine rhodamine B sulfonyl didodecyl amine (LRSD) is soluble in chloroform. • LRSD shows robust quantum yield in solution and as a dopant in thin film. • LRSD is an amphiphilic rhodamine dye that forms compact fluorescent micelles. • LRSD forms a stable isotherm when spread at the air–water interface.

  2. Preparation and Microbiological Evaluation of Amphiphilic Kanamycin-Lipoamino Acid Ion-Pairs

    Directory of Open Access Journals (Sweden)

    Rosario Pignatello

    2014-05-01

    Full Text Available Amphiphilic ion-pairs of kanamycin (KAN were prepared by evaporation of a water-ethanol co-solution of KAN base and a lipoamino acid bearing a 12-carbon atoms alkyl side chain (LAA12, at different molar ratios. Infrared spectroscopy confirmed the structure of ion-pairs, while differential scanning calorimetry (DSC and powder X-ray diffractometry (PXRD studies supported the formation of new saline species with a different crystalline structure than the starting components. The solubility pattern shown in a range of both aqueous and organic solvents confirmed that the ion-pairs possess an amphiphilic character. The LAA12 counter-ion showed not to improve the antibacterial activity of KAN, suggesting that such chemical strategy is not able to favor the penetration of this drug inside the bacteria cells. Nevertheless, a slight improving, i.e., a one-fold dilution, was observed in E. coli. The present study can also serve as the basis for a further evaluation of LAA ion-pairing of antibiotics, as a means to improve the loading of hydrophilic drugs into lipid-based nanocarriers.

  3. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    International Nuclear Information System (INIS)

    Fullerene C60 sub-colloidal particle with diameter ∼1 nm represents a boundary case between small and large hydrophobic solutes on the length scale of hydrophobic hydration. In the present paper, a molecular dynamics simulation is performed to investigate this complex phenomenon for bare C60 fullerene and its amphiphilic/charged derivatives, so called shape amphiphiles. Since most of the unique properties of water originate from the pattern of hydrogen bond network and its dynamics, spatial, and orientational aspects of water in solvation shells around the solute surface having hydrophilic and hydrophobic regions are analyzed. Dynamical properties such as translational-rotational mobility, reorientational correlation and occupation time correlation functions of water molecules, and diffusion coefficients are also calculated. Slower dynamics of solvent molecules—water retardation—in the vicinity of the solutes is observed. Both the topological properties of hydrogen bond pattern and the “dangling” –OH groups that represent surface defects in water network are monitored. The fraction of such defect structures is increased near the hydrophobic cap of fullerenes. Some “dry” regions of C60 are observed which can be considered as signatures of surface dewetting. In an effort to provide molecular level insight into the thermodynamics of hydration, the free energy of solvation is determined for a family of fullerene particles using thermodynamic integration technique

  4. Using amphiphilic nanostructures to enable long-range ensemble coalescence and surface rejuvenation in dropwise condensation.

    Science.gov (United States)

    Anderson, David M; Gupta, Maneesh K; Voevodin, Andrey A; Hunter, Chad N; Putnam, Shawn A; Tsukruk, Vladimir V; Fedorov, Andrei G

    2012-04-24

    Controlling coalescence events in a heterogeneous ensemble of condensing droplets on a surface is an outstanding fundamental challenge in surface and interfacial sciences, with a broad practical importance in applications ranging from thermal management of high-performance electronic devices to moisture management in high-humidity environments. Nature-inspired superhydrophobic surfaces have been actively explored to enhance heat and mass transfer rates by achieving favorable dynamics during dropwise condensation; however, the effectiveness of such chemically homogeneous surfaces has been limited because condensing droplets tend to form as pinned Wenzel drops rather than mobile Cassie ones. Here, we introduce an amphiphilic nanostructured surface, consisting of a hydrophilic base with hydrophobic tips, which promotes the periodic regeneration of nucleation sites for small droplets, thus rendering the surface self-rejuvenating. This unique amphiphilic nanointerface generates an arrangement of condensed Wenzel droplets that are fluidically linked by a wetted sublayer, promoting previously unobserved coalescence events where numerous droplets simultaneously merge, without direct contact. Such ensemble coalescences rapidly create fresh nucleation sites, thereby shifting the overall population toward smaller droplets and enhancing the rates of mass and heat transfer during condensation.

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

    Science.gov (United States)

    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.

  6. Oligonucleotide delivery with cell surface binding and cell penetrating Peptide amphiphile nanospheres.

    Science.gov (United States)

    Mumcuoglu, Didem; Sardan, Melis; Tekinay, Turgay; Guler, Mustafa O; Tekinay, Ayse B

    2015-05-01

    A drug delivery system designed specifically for oligonucleotide therapeutics can ameliorate the problems associated with the in vivo delivery of these molecules. The internalization of free oligonucleotides is challenging, and cytotoxicity is the main obstacle for current transfection vehicles. To develop nontoxic delivery vehicles for efficient transfection of oligonucleotides, we designed a self-assembling peptide amphiphile (PA) nanosphere delivery system decorated with cell penetrating peptides (CPPs) containing multiple arginine residues (R4 and R8), and a cell surface binding peptide (KRSR), and report the efficiency of this system in delivering G-3129, a Bcl-2 antisense oligonucleotide (AON). PA/AON (peptide amphiphile/antisense oligonucleotide) complexes were characterized with regards to their size and secondary structure, and their cellular internalization efficiencies were evaluated. The effect of the number of arginine residues on the cellular internalization was investigated by both flow cytometry and confocal imaging, and the results revealed that uptake efficiency improved as the number of arginines in the sequence increased. The combined effect of cell penetration and surface binding property on the cellular internalization and its uptake mechanism was also evaluated by mixing R8-PA and KRSR-PA. R8 and R8/KRSR decorated PAs were found to drastically increase the internalization of AONs compared to nonbioactive PA control. Overall, the KRSR-decorated self-assembled PA nanospheres were demonstrated to be noncytotoxic delivery vectors with high transfection rates and may serve as a promising delivery system for AONs. PMID:25828697

  7. Rapidly recovering hydrogel scaffolds from self-assembling diblock copolypeptide amphiphiles

    Science.gov (United States)

    Nowak, Andrew P.; Breedveld, Victor; Pakstis, Lisa; Ozbas, Bulent; Pine, David J.; Pochan, Darrin; Deming, Timothy J.

    2002-05-01

    Protein-based hydrogels are used for many applications, ranging from food and cosmetic thickeners to support matrices for drug delivery and tissue replacement. These materials are usually prepared using proteins extracted from natural sources, which can give rise to inconsistent properties unsuitable for medical applications. Recent developments have utilized recombinant DNA methods to prepare artificial protein hydrogels with specific association mechanisms and responsiveness to various stimuli. Here we synthesize diblock copolypeptide amphiphiles containing charged and hydrophobic segments. Dilute solutions of these copolypeptides would be expected to form micelles; instead, they form hydrogels that retain their mechanical strength up to temperatures of about 90°C and recover rapidly after stress. The use of synthetic materials permits adjustment of copolymer chain length and composition, which we varied to study their effect on hydrogel formation and properties. We find that gelation depends not only on the amphiphilic nature of the polypeptides, but also on chain conformations-α-helix, β-strand or random coil. Indeed, shape-specific supramolecular assembly is integral to the gelation process, and provides a new class of peptide-based hydrogels with potential for applications in biotechnology.

  8. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    Energy Technology Data Exchange (ETDEWEB)

    Varanasi, S. R., E-mail: s.raovaranasi@uq.edu.au, E-mail: guskova@ipfdd.de; John, A. [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Guskova, O. A., E-mail: s.raovaranasi@uq.edu.au, E-mail: guskova@ipfdd.de [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden D-01069 (Germany); Sommer, J.-U. [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden D-01069 (Germany); Institut für Theoretische Physik, Technische Universität Dresden, Zellescher Weg 17, Dresden D-01069 (Germany)

    2015-06-14

    Fullerene C{sub 60} sub-colloidal particle with diameter ∼1 nm represents a boundary case between small and large hydrophobic solutes on the length scale of hydrophobic hydration. In the present paper, a molecular dynamics simulation is performed to investigate this complex phenomenon for bare C{sub 60} fullerene and its amphiphilic/charged derivatives, so called shape amphiphiles. Since most of the unique properties of water originate from the pattern of hydrogen bond network and its dynamics, spatial, and orientational aspects of water in solvation shells around the solute surface having hydrophilic and hydrophobic regions are analyzed. Dynamical properties such as translational-rotational mobility, reorientational correlation and occupation time correlation functions of water molecules, and diffusion coefficients are also calculated. Slower dynamics of solvent molecules—water retardation—in the vicinity of the solutes is observed. Both the topological properties of hydrogen bond pattern and the “dangling” –OH groups that represent surface defects in water network are monitored. The fraction of such defect structures is increased near the hydrophobic cap of fullerenes. Some “dry” regions of C{sub 60} are observed which can be considered as signatures of surface dewetting. In an effort to provide molecular level insight into the thermodynamics of hydration, the free energy of solvation is determined for a family of fullerene particles using thermodynamic integration technique.

  9. Effect of headgroup-substrate interactions on the thermal behavior of long-chain amphiphiles

    Science.gov (United States)

    Singla, Saranshu; Zhu, He; Dhinojwala, Ali

    The structure of amphiphilic molecules at liquid/solid and solid/solid interfaces is relevant in understanding lubrication, colloid stabilization, chromatography, and nucleation. Here, we characterize the interfacial structures of long chain amphiphilic molecules with different head groups (OH, COOH, NH2) using interface-sensitive sum frequency generation (SFG) spectroscopy. The behavior of these self-assembled monolayers (SAMs) on sapphire substrate is recorded in situ as a function of temperature (above and below bulk Tm) using SFG. Previous studies using synchrotron X-ray reflectivity and SFG show that the melting point of an ordered hexadecanol monolayer is around 30°C above its bulk Tm. The thermal stability of the monolayer is explained due to strong hydrogen bonding interactions between the head-group and the sapphire substrate. The strength of these hydrogen-bonding interactions between substrate and different head groups is calculated using the Badger-Bauer equation. Below Tm, the ordered monolayer influenced the structure of the interfacial crystalline layer, and the transition from monolayer to the bulk crystalline phases. The results with different head groups will be presented.

  10. Design of amphiphilic oligopeptides as models for fine tuning peptide assembly with plasmid DNA.

    Science.gov (United States)

    Goparaju, Geetha N; Gupta, Pardeep K

    2014-08-01

    We discuss the design of novel amphiphilic oligopeptides with hydrophobic and cationic amino acids to serve as models to understand peptide-DNA assembly. Biophysical and thermodynamic characterization of interaction of these amphiphilic peptides with plasmid DNA is presented. Peptides with at least +4 charges favor stable complex formation. Surface potential is dependent on the type of hydrophobic amino acid for a certain charge. Thermodynamically it is a spontaneous interaction between most of the peptides and plasmid DNA. Lys(7) and Tyr peptides with +4/+5 charges indicate cooperative binding with pDNA without saturation of interaction while Val(2)-Gly-Lys(4), Val-Gly-Lys(5), and Phe-Gly-Lys(5) lead to saturation of interaction indicating condensed pDNA within the range of N/Ps studied. We show that the biophysical properties of DNA-peptide complexes could be modulated by design and the peptides presented here could be used as building blocks for creating DNA-peptide complexes for various biomedical applications, mainly nucleic acid delivery.

  11. First-order phase transition during displacement of amphiphilic biomacromolecules from interfaces by surfactant molecules.

    Science.gov (United States)

    Ettelaie, Rammile; Dickinson, Eric; Pugnaloni, Luis

    2014-11-19

    The adsorption of surfactants onto a hydrophobic interface, already laden with a fixed number of amphiphilic macromolecules, is studied using the self consistent field calculation method of Scheutjens and Fleer. For biopolymers having unfavourable interactions with the surfactant molecules, the adsorption isotherms show an abrupt jump at a certain value of surfactant bulk concentration. Alternatively, the same behaviour is exhibited when the number of amphiphilic chains on the interface is decreased. We show that this sudden jump is associated with a first-order phase transition, by calculating the free energy values for the stable and the metastable states at both sides of the transition point. We also observe that the transition can occur for two approaching surfaces, from a high surfactant coverage phase to a low surfactant coverage one, at sufficiently close separation distances. The consequence of this finding for the steric colloidal interactions, induced by the overlap of two biopolymer + surfactant films, is explored. In particular, a significantly different interaction, in terms of its magnitude and range, is predicted for these two phases. We also consider the relevance of the current study to problems involving the competitive displacement of proteins by surfactants in food colloid systems.

  12. Self-Assembling Nanoparticles of Amphiphilic Polymers for In Vitro and In Vivo FRET Imaging.

    Science.gov (United States)

    Garcia-Amorós, Jaume; Tang, Sicheng; Zhang, Yang; Thapaliya, Ek Raj; Raymo, Françisco M

    2016-01-01

    Self-assembling nanoparticles of amphiphilic polymers are viable delivery vehicles for transporting hydrophobic molecules across hydrophilic media. Noncovalent contacts between the hydrophobic domains of their macromolecular components are responsible for their formation and for providing a nonpolar environment for the encapsulated guests. However, such interactions are reversible and, as a result, these supramolecular hosts can dissociate into their constituents amphiphiles to release the encapsulated cargo. Operating principles to probe the integrity of the nanocarriers and the dynamic exchange of their components are, therefore, essential to monitor the fate of these supramolecular assemblies in biological media. The co-encapsulation of complementary chromophores within their nonpolar interior offers the opportunity to assess their stability on the basis of energy transfer and fluorescence measurements. Indeed, the exchange of excitation energy between the entrapped chromophores can only occur if the nanoparticles retain their integrity to maintain donors and acceptors in close proximity. In fact, energy-transfer schemes are becoming invaluable protocols to elucidate the transport properties of these fascinating supramolecular constructs in a diversity of biological preparations and can facilitate the identification of strategies to deliver contrast agents and/or drugs to target locations in living organisms for potential diagnostic and/or therapeutic applications. PMID:26589505

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

    Science.gov (United States)

    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

  14. The membrane interaction of amphiphilic model peptides affects phosphatidylserine headgroup and acyl chain order and dynamics. Application of the phospholipid headgroup electrometer concept to phosphatidylserine

    International Nuclear Information System (INIS)

    Deuterium nuclear magnetic resonance (2H NMR) was used to study the interaction of amphiphilic model peptides with model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phospho-L-serine deuterated either at the β-position of the serine moiety ([2-2H]DOPS) or at the 11-position of the acyl chains ([11,11-2H2]DOPS). The peptides are derived from the sequences H-Ala-Met-Leu-Trp-Ala-OH and H-Arg-Met-Leu-Trp-Ala-OH and contain a positive charge of +1 or +2 at the amino terminus or one positive charge at each end of the molecule. Upon titration of dispersions of DOPS with the peptides, the divalent peptides show a similar extent of binding to the DOPS bilyers, which is larger than that of the single charged peptide. Under these conditions the values of the quadrupolar splitting of both [2-2H]DOPS and [11,11-2H2]DOPS are decreased, indicating that the peptides reduce the order of both the DOPS headgroup and the acyl chains. The extent of the decrease depends on the amount of peptide bound and on the position of the charged moieties in the peptide molecule. Titrations of DOPS with poly(L-lysine)100, which were included for reasons of comparison, reveal increased Δvq values. When the peptide-lipid titrations are carried out without applying a freeze-thaw procedure to achieve full equilibration, two-component 2H NMR spectra occur. The apparently limited accessibility of the lipid to the peptides under these circumstances is discussed in relation to the ability of the peptides to exhibit transbilayer movement. 2H spin-lattice relaxation time T1 measurements demonstrate a decrease of the rates of motion of both headgroup and acyl chains of DOPS in the presence of the peptides

  15. The membrane interaction of amphiphilic model peptides affects phosphatidylserine headgroup and acyl chain order and dynamics. Application of the phospholipid headgroup electrometer concept to phosphatidylserine

    Energy Technology Data Exchange (ETDEWEB)

    de Kroon, A.I.P.M.; Killian, J.A.; de Gier, J.; de Kruijff, B. (Univ. of Utrecht (Netherlands))

    1991-01-29

    Deuterium nuclear magnetic resonance ({sup 2}H NMR) was used to study the interaction of amphiphilic model peptides with model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phospho-L-serine deuterated either at the {beta}-position of the serine moiety ((2-{sup 2}H)DOPS) or at the 11-position of the acyl chains ((11,11-{sup 2}H{sub 2})DOPS). The peptides are derived from the sequences H-Ala-Met-Leu-Trp-Ala-OH and H-Arg-Met-Leu-Trp-Ala-OH and contain a positive charge of +1 or +2 at the amino terminus or one positive charge at each end of the molecule. Upon titration of dispersions of DOPS with the peptides, the divalent peptides show a similar extent of binding to the DOPS bilyers, which is larger than that of the single charged peptide. Under these conditions the values of the quadrupolar splitting of both (2-{sup 2}H)DOPS and (11,11-{sup 2}H{sub 2})DOPS are decreased, indicating that the peptides reduce the order of both the DOPS headgroup and the acyl chains. The extent of the decrease depends on the amount of peptide bound and on the position of the charged moieties in the peptide molecule. Titrations of DOPS with poly(L-lysine){sub 100}, which were included for reasons of comparison, reveal increased {Delta}v{sub q} values. When the peptide-lipid titrations are carried out without applying a freeze-thaw procedure to achieve full equilibration, two-component {sup 2}H NMR spectra occur. The apparently limited accessibility of the lipid to the peptides under these circumstances is discussed in relation to the ability of the peptides to exhibit transbilayer movement. {sup 2}H spin-lattice relaxation time T1 measurements demonstrate a decrease of the rates of motion of both headgroup and acyl chains of DOPS in the presence of the peptides.

  16. Pharmacokinetics and antitumor efficacy of micelles assembled from multiarmed amphiphilic copolymers with drug conjugates in comparison with drug-encapsulated micelles.

    Science.gov (United States)

    Luo, Xiaoming; Chen, Maohua; Zhang, Yun; Chen, Zhoujiang; Li, Xiaohong

    2016-01-01

    The premature drug release and structural dissociation before reaching pathological sites have posed major challenges for self-assembled micelles. To address these challenges, star-shaped amphiphilic copolymers derived from 4-armed poly(ethylene glycol) (PEG) were proposed for chemical conjugation of chemotherapeutic drugs and assembly into drug-conjugated micelles (DCM) with reductive sensitivity. The current study aimed to elucidate the in vitro and in vivo performance of DCM and a comparison with conventional drug-encapsulated micelles (DEM) was initially launched. DEM carriers were constructed with a similar structure to DCM from 4-armed PEG, and disulfide linkages were located between the hydrophilic and hydrophobic segments. Both DCM and DEM had an average size of around 130 nm, camptothecin (CPT) loadings of around 7.7% and critical micelle concentrations of around 0.95 μg/ml. Compared with DEM, DCM showed a lower initial drug release, a lower sensitivity of drug release to glutathione, and a higher structural stability after incubation with human serum albumin (HSA). The CPT derivatives (CPT-SH) released from DCM indicated cytotoxicities similar to CPT and remained a higher lactone stability than CPT in the presence of HSA. DCM showed slightly higher cytotoxicities to 4T1 cells and significantly lower cytotoxicities to normal cells than DEM. Pharmacokinetic analyses after intravenous administration of DCM indicated around 2.65 folds higher AUC0-∞, 2.66 folds lower clearance, and 1.87 folds higher tumor accumulation than those of DEM. In addition to a less disturbance to hematological and biochemical parameters and a lower acute toxicity to small intestines, DCM showed more significant tumor suppression efficacy and less tumor metastasis to lungs than DEM. It is suggested that DCM could overcome the limitation of conventional micelles by alleviating the premature drug release during blood circulation, relieving the systemic toxicity and promoting the

  17. Staphylococcal α -toxin: Oligomerization of Hydrophilic Monomers to Form Amphiphilic Hexamers Induced through Contact with Deoxycholate Detergent Micelles

    Science.gov (United States)

    Bhakdi, Sucharit; Fussle, Roswitha; Tranum-Jensen, Jorgen

    1981-09-01

    Native staphylococcus aureus α -toxin is secreted as a hydrophilic polypeptide chain of Mr 34,000. The presence of deoxycholate above the critical micellar concentration induced the toxin monomers to self-associate, forming ring or cylindrical oligomers. The oligomers were amphiphilic and bound detergent. In deoxycholate solution, the protein-detergent complexes exhibited a sedimentation coefficient of 10.4 S. A Mr of 238,700 was determined by ultracentrifugation analyses at sedimentation equilibrium. Because quantitative detergent-binding studies indicated a protein/detergent ratio of approximately 5:1 (wt/wt), the protein moiety in each protein-detergent complex was determined to be approximately Mr 200 000, corresponding to a hexamer of the native molecule. The amphiphilic toxin hexamers were ultrastructurally indistinguishable from the cytolytic, annular toxin complexes that form on and in biological target membranes. They bound lipid and could be incorporated into artificial lecithin lipid vesicles. The transition of toxin protein molecules from a hydrophilic monomer to an amphiphilic oligomer through self-association has thus been shown to be inducible solely through contact of the native protein molecules with an appropriate amphiphilic substrate.

  18. Amphiphilic polymeric micelles as microreactors: improving the photocatalytic hydrogen production of the [FeFe]-hydrogenase mimic in water.

    Science.gov (United States)

    Wang, Feng; Wen, Min; Feng, Ke; Liang, Wen-Jing; Li, Xu-Bing; Chen, Bin; Tung, Chen-Ho; Wu, Li-Zhu

    2016-01-11

    An amphiphilic polymeric micelle is utilized as a microreactor to load a hydrophobic [FeFe]-hydrogenase mimic in water. The local concentration enhancement and strong interaction between the mimic and the photosensitizer as well as the water-mediated fast proton migration caused by the microreactor improve photocatalytic hydrogen production remarkably in water. PMID:26442776

  19. Amphiphilic drugs as surfactants to fabricate excipient-free stable nanodispersions of hydrophobic drugs for cancer chemotherapy.

    Science.gov (United States)

    Hu, Shiqi; Lee, Eunhye; Wang, Chi; Wang, Jinqiang; Zhou, Zhuxian; Li, Yixian; Li, Xiaoyi; Tang, Jianbin; Lee, Don Haeng; Liu, Xiangrui; Shen, Youqing

    2015-12-28

    Nanoformulations have been extensively explored to deliver water-insoluble drugs, but they generally use exotic new materials, for instance, amphiphilic block copolymers, which must first go through extensively clinical trials and be approved as drug excipients before any clinical uses. We hypothesize that using clinical amphiphilic drugs as surfactants to self-assemble with and thus solubilize hydrophobic drugs will lead to readily translational nanoformulations as they contain no new excipients. Herein, we show the first example of such excipient-free nanodispersions using an amphiphilic anti-tumor drug, irinotecan hydrochloride (CPT11). CPT11 self-assembles with its insoluble active parent drug, 7-ethyl-10-hydroxy camptothecin (SN38), into stable and water-dispersible nanoparticles, increasing SN38's water solubility by thousands of times up to 25 mg/mL with a loading efficiency close to 100%. The versatility of this approach is also demonstrated by fabricating nanodispersions of CPT11 with other water-insoluble drugs including paclitaxel (PTX) and camptothecin (CPT). These nanodispersions have much increased bioavailability and thereby improved anti-cancer activities. Thus, this strategy, using clinically proven amphiphilic drugs as excipients to fabricate nanodispersions, avoids new materials and makes readily translational nanoformulations of hydrophobic drugs.

  20. A Rational Approach to the Origin of Life: From Amphiphilic Molecules to Protocells. Some Plausible Solutions, and Some Real Problems

    Science.gov (United States)

    Ourisson, Guy; Nakatani, Yoichi

    Self-organisation of amphiphiles in water into closed vesicles leads automatically to self-complexification into "protocells". However, some real problems are usually not even mentioned in the various theories of the origin of Life. The present discussion is a follow up of our initial publications (Ourisson and Nakatani, 1994, 1999; see Maddox, 1994)

  1. Amphiphilic hollow porous shell encapsulated Au@Pd bimetal nanoparticles for aerobic oxidation of alcohols in water

    KAUST Repository

    Zou, Houbing

    2015-01-01

    © The Royal Society of Chemistry 2015. This work describes the design, synthesis and analysis of an amphiphilic hollow mesoporous shell encapsulating catalytically active Au@Pd bimetal nanoparticles. The particles exhibited excellent catalytic activity and stability in the aerobic oxidation of primary and secondary alcohols to their corresponding aldehydes or ketones in water when using air as an oxidizing agent under atmospheric pressure.

  2. Deconvoluting the Effect of the Hydrophobic and Hydrophilic Domains of an Amphiphilic Integral Membrane Protein in Lipid Bicontinuous Cubic Mesophases.

    Science.gov (United States)

    van 't Hag, Leonie; Shen, Hsin-Hui; Lu, Jingxiong; Hawley, Adrian M; Gras, Sally L; Drummond, Calum J; Conn, Charlotte E

    2015-11-10

    Lipidic bicontinuous cubic mesophases with encapsulated amphiphilic proteins are widely used in a range of biological and biomedical applications, including in meso crystallization, as drug delivery vehicles for therapeutic proteins, and as biosensors and biofuel cells. However, the effect of amphiphilic protein encapsulation on the cubic phase nanostructure is not well-understood. In this study, we illustrate the effect of incorporating the bacterial amphiphilic membrane protein Ag43, and its individual hydrophobic β(43) and hydrophilic α(43) domains, in bicontinuous cubic mesophases. For the monoolein, monoalmitolein, and phytantriol cubic phases with and without 8% w/w cholesterol, the effect of the full length amphiphilic protein Ag43 on the cubic phase nanostructure was more significant than the sum of the individual hydrophobic β(43) and hydrophilic α(43) domains. Several factors were found to potentially influence the impact of the hydrophobic β(43) domain on the cubic phase internal nanostructure. These include the size of the hydrophobic β(43) domain relative to the thickness of the lipid bilayer, as well as its charge and diameter. The size of the hydrophilic α(43) domain relative to the water channel radius of the cubic mesophase was also found to be important. The secondary structure of the Ag43 proteins was affected by the hydrophobic thickness and physicochemical properties of the lipid bilayer and the water channel diameter of the cubic phase. Such structural changes may be small but could potentially affect membrane protein function.

  3. Self-assembled structures of amphiphilic ionic block copolymers: Theory, self-consistent field modeling and experiment

    NARCIS (Netherlands)

    Borisov, O.V.; Zhulina, E.B.; Leermakers, F.A.M.; Muller, A.H.E.

    2011-01-01

    We present an overview of statistical thermodynamic theories that describe the self-assembly of amphiphilic ionic/hydrophobic diblock copolymers in dilute solution. Block copolymers with both strongly and weakly dissociating (pH-sensitive) ionic blocks are considered. We focus mostly on structural a

  4. Self-assembly of amphiphilic anionic calix[4]arenes and encapsulation of poorly soluble naproxen and flurbiprofen.

    Science.gov (United States)

    Barbera, Lucia; Gattuso, Giuseppe; Kohnke, Franz H; Notti, Anna; Pappalardo, Sebastiano; Parisi, Melchiorre F; Pisagatti, Ilenia; Patanè, Salvatore; Micali, Norberto; Villari, Valentina

    2015-06-21

    Supramolecular aggregates formed through the association of an amphiphilic tetra-O-butylsulfonate calix[4]arene 1 were investigated in aqueous solution by a combination of different techniques (NMR, DLS and AFM). The ability of the micellar aggregates of calixarene 1 to increase the solubility of poorly water-soluble drugs was studied.

  5. Polymorphism of pyridinium amphiphiles for gene delivery : Influence of ionic strength, helper lipid content, and plasmid DNA complexation

    NARCIS (Netherlands)

    Scarzello, M; Chupin, [No Value; Wagenaar, A; Stuart, MCA; Engberts, JBFN; Hulst, R; Chupin, Vladimir

    2005-01-01

    Two double-tailed pyridinium cationic amphiphiles, differing only in the degree of unsaturation of the alkyl chains, have been selected for a detailed study of their aggregation behavior, under conditions employed for transfection experiments. The transfection efficiencies of the two molecules are r

  6. Fabrication of alternating multilayers of a diacetylene group containing amphiphilic ligand and acid, using the Langmuir-Blodgett technique

    NARCIS (Netherlands)

    Werkman, PJ; Wieringa, RH; Schouten, AJ

    1997-01-01

    The structure of alternating multilayers of two diacetylene group containing amphiphiles (an acid (A) and a pyridine ligand (B)), built up from a 5 mM CdBr2 subphase, is examined. SAXR measurements revealed that these multilayers have a regular layer structure with a bilayer spacing of 55.2 Angstrom

  7. Unlocking Chain Exchange in Highly Amphiphilic Block Polymer Micellar Systems: Influence of Agitation

    OpenAIRE

    Murphy, Ryan P.; Kelley, Elizabeth G.; Rogers, Simon A.; Sullivan, Millicent O.; Epps, Thomas H.

    2014-01-01

    Chain exchange between block polymer micelles in highly selective solvents, such as water, is well-known to be arrested under quiescent conditions, yet this work demonstrates that simple agitation methods can induce rapid chain exchange in these solvents. Aqueous solutions containing either pure poly(butadiene-b-ethylene oxide) or pure poly(butadiene-b-ethylene oxide-d 4) micelles were combined and then subjected to agitation by vortex mixing, concentric cylinder Couette flow, or nitrogen gas...

  8. Synthesis of apolipoprotein B lipoparticles to deliver hydrophobic/amphiphilic materials.

    Science.gov (United States)

    Chu, Hsueh-Liang; Cheng, Tsai-Mu; Chen, Hung-Wei; Chou, Fu-Hsuan; Chang, Yu-Chuan; Lin, Hsin-Yu; Liu, Shih-Yi; Liang, Yu-Chuan; Hsu, Ming-Hua; Wu, Dian-Shyeu; Li, Hsing-Yuan; Ho, Li-Ping; Wu, Ping-Ching; Chen, Fu-Rong; Chen, Gong-Shen; Shieh, Dar-Bin; Chang, Chia-Seng; Su, Chia-Hao; Yao, Zemin; Chang, Chia-Ching

    2013-08-14

    To develop a drug delivery system (DDS), it is critical to address challenging tasks such as the delivery of hydrophobic and amphiphilic compounds, cell uptake, and the metabolic fate of the drug delivery carrier. Low-density lipoprotein (LDL) has been acknowledged as the human serum transporter of natively abundant lipoparticles such as cholesterol, triacylglycerides, and lipids. Apolipoprotein B (apo B) is the only protein contained in LDL, and possesses a binding moiety for the LDL receptor that can be internalized and degraded naturally by the cell. Therefore, synthetic/reconstituting apoB lipoparticle (rABL) could be an excellent delivery carrier for hydrophobic or amphiphilic materials. Here, we synthesized rABL in vitro, using full-length apoB through a five-step solvent exchange method, and addressed its potential as a DDS. Our rABL exhibited good biocompatibility when evaluated with cytotoxicity and cell metabolic response assays, and was stable during storage in phosphate-buffered saline at 4 °C for several months. Furthermore, hydrophobic superparamagnetic iron oxide nanoparticles (SPIONPs) and the anticancer drug M4N (tetra-O-methyl nordihydroguaiaretic acid), used as an imaging enhancer and lipophilic drug model, respectively, were incorporated into the rABL, leading to the formation of SPIONPs- and M4N- containing rABL (SPIO@rABL and M4N@rABL, respectively). Fourier transform infrared spectroscopy suggested that rABL has a similar composition to that of LDL, and successfully incorporated SPIONPs or M4N. SPIO@rABL presented significant hepatic contrast enhancement in T2-weighted magnetic resonance imaging in BALB/c mice, suggesting its potential application as a medical imaging contrast agent. M4N@rABL could reduce the viability of the cancer cell line A549. Interestingly, we developed solution-phase high-resolution transmission electron microscopy to observe both LDL and SPIO@rABL in the liquid state. In summary, our LDL-based DDS, rABL, has

  9. Hydrophobic cotton textile surfaces using an amphiphilic graphene oxide (GO) coating

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Different GO dispersions were prepared by sonicating different amounts of GO in water. Degree of exfoliation of these GO sheets in water was analyzed using Atomic Force Microscopy (AFM). • AFM results obtained showed higher the GO concentration on water more the size of GO sheets and lesser the degree of exfoliation. • GO with different amounts was deposited on cotton fabric using simple dyeing method. • High GO loading on cotton increase the surface area coverage of the textile fibers with GO sheets. This led to less edge to mid area ratio of grafted GO sheets. • As contribution of mid area of GO increase on fiber surface cotton fabric becomes more hydrophobic. • Amphiphilic property of GO sheets was used to lower the surface energy of the cotton fibers leading to hydrophobic property. - Abstract: We report for the first time hydrophobic properties on cotton fabric successfully achieved by grafting graphene oxide on the fabric surface, using a dyeing method. Graphite oxide synthesized by oxidizing natural flake graphite employing improved Hummer's method showed an inter layer spacing of ∼1 nm from XRD. Synthesized graphite oxide was exfoliated in water using ultrasound energy to obtain graphene oxide (GO). AFM data obtained for the graphene oxide dispersed in an aqueous medium revealed a non-uniform size distribution. FTIR characterization of the synthesized GO sheets showed both hydrophilic and hydrophobic functional groups present on the nano sheets giving them an amphiphilic property. GO flakes of different sizes were successfully grafted on to a cotton fabric surface using a dip dry method. Loading different amounts of graphene oxide on the cotton fiber surface allowed the fabric to demonstrate different degrees of hydrophobicity. The highest observed water contact angle was at 143° with the highest loading of graphene oxide. The fabric surfaces grafted with GO also exhibits adhesive type hydrophobicity

  10. Amphiphilic, hydrophilic, or hydrophobic synthetic bacteriochlorins in biohybrid light-harvesting architectures: consideration of molecular designs.

    Science.gov (United States)

    Jiang, Jianbing; Reddy, Kanumuri Ramesh; Pavan, M Phani; Lubian, Elisa; Harris, Michelle A; Jiao, Jieying; Niedzwiedzki, Dariusz M; Kirmaier, Christine; Parkes-Loach, Pamela S; Loach, Paul A; Bocian, David F; Holten, Dewey; Lindsey, Jonathan S

    2014-11-01

    Biohybrid light-harvesting architectures can be constructed that employ native-like bacterial photosynthetic antenna peptides as a scaffold to which synthetic chromophores are attached to augment overall spectral coverage. Synthetic bacteriochlorins are attractive to enhance capture of solar radiation in the photon-rich near-infrared spectral region. The effect of the polarity of the bacteriochlorin substituents on the antenna self-assembly process was explored by the preparation of a bacteriochlorin-peptide conjugate using a synthetic amphiphilic bacteriochlorin (B1) to complement prior studies using hydrophilic (B2, four carboxylic acids) or hydrophobic (B3) bacteriochlorins. The amphiphilic bioconjugatable bacteriochlorin B1 with a polar ammonium-terminated tail was synthesized by sequential Pd-mediated reactions of a 3,13-dibromo-5-methoxybacteriochlorin. Each bacteriochlorin bears a maleimido-terminated tether for attachment to a cysteine-containing analog of the Rhodobacter sphaeroides antenna β-peptide to give conjugates β-B1, β-B2, and β-B3. Given the hydrophobic nature of the β-peptide, the polarity of B1 and B2 facilitated purification of the respective conjugate compared to the hydrophobic B3. Bacteriochlorophyll a (BChl a) associates with each conjugate in aqueous micellar media to form a dyad containing two β-peptides, two covalently attached synthetic bacteriochlorins, and a datively bonded BChl-a pair, albeit to a limited extent for β-B2. The reversible assembly/disassembly of dyad (β-B2/BChl)2 was examined in aqueous detergent (octyl glucoside) solution by temperature variation (15-35 °C). The energy-transfer efficiency from the synthetic bacteriochlorin to the BChl-a dimer was found to be 0.85 for (β-B1/BChl)2, 0.40 for (β-B2/BChl)2, and 0.85 for (β-B3/BChl)2. Thus, in terms of handling, assembly and energy-transfer efficiency taken together, the amphiphilic design examined herein is more attractive than the prior hydrophilic or

  11. Synthesis by ATRP of poly(ethylene-co-butylene)-block-polystyrene, poly(ethylene-co-butylene)-block-poly(4-acetoxystyrene) and its hydrolysis product poly(ethylene-co-butylene)-block-poly(hydroxystyrene)

    DEFF Research Database (Denmark)

    Jankova, Katja; Kops, Jørgen; Chen, Xianyi;

    1999-01-01

    Diblock copolymers of poly(ethylene-co-butylene) and polystyrene or poly(4-acetoxystyrene) are synthesized by atom transfer radical polymerization (ATRP) using a 2-bromopropionic ester macroinitiator prepared from commercial monohydroxyl functional narrow dispersity hydrogenated polybutadiene...... copolymer with poly(4-acetoxystyrene) was hydrolyzed to the corresponding poly(4-hydroxystyrene) sequence....

  12. PolyZen的工作原理

    Institute of Scientific and Technical Information of China (English)

    方佩敏

    2009-01-01

    PolyZen是一种新型过流、过压保护器件,是泰科电子(Tyco)公司开发的器件。PolyZen是PolySwitch和Zener两个字组合成的,PolySwitch是一种非线性聚合物正温度系数热敏电阻(PPTC),Zener是齐纳二极管(稳压二极管)。PolySwitch作过流保护器用,而Zener作过压保护器用。

  13. Hydrogels formed by enantioselective self-assembly of histidine-derived amphiphiles with tartaric acid.

    Science.gov (United States)

    Zhang, Fanjun; Xu, Zhenghu; Dong, Shuli; Feng, Lei; Song, Aixin; Tung, Chen-Ho; Hao, Jingcheng

    2014-07-21

    Two chiral enantiomers of histidine-derived amphiphilic gelators, (4R,6S)-UIPCA and (4S,6R)-UIPCA, were synthesized through Pictet-Spengler reaction and their gelation behaviors with different organic acids were investigated. Interestingly, the chiral enantiomers of UIPCA showed smart enantioselectivity for gelating tartaric acid enantiomers to form hydrogels with excellent mechanical strength. The TEM and SEM images demonstrated that the hydrogels were composed of networks by physical entanglement of nanofibers with high aspect ratios. The formation of nanofibers was considered to be driven by the interplay of hydrogen bonding, electrostatic attraction, and hydrophobic interaction, which was supported by XRD and FT-IR spectra. The hydrogels exhibited sensitive response to a series of external stimuli, such as temperature, metal ions, and host-guest interactions, to realize the reversible gel-sol transition. The property of the gelation was elaborated and the gelators were expected to find their applications in chiral discrimination. PMID:24865976

  14. Mixed Langmuir monolayers of an amphiphilic chromo-ionophore and the phospholipid DMPC

    Science.gov (United States)

    Sergeeva, T. I.; Gromov, S. P.; Vedernikov, A. I.; Kapichnikova, M. S.; Alfimov, M. V.; Möbius, D.; Zaitsev, S. Yu.

    2005-06-01

    The amphiphilic chromo-ionophore 2-[(1E,3E)-4-(2,3,5,6,8,9,11,12,14,15-decahydro-1,7,10,16,4,13-benzotetraoxadithiacyclooctadecin-18-yl)-1,3-butadienyl]-3-octadecyl-1,3-benzothiazol-3-ium perchlorate (AB211) forms mixed monolayers at the air-water interface with the phospholipid L-α-dimyristoylphosphatidylcholine (DMPC) as deduced from surface pressure-area and surface potential-area isotherms. In contrast to the behaviour of pure monolayers of AB211 on water, no association of the chromophores is observed by reflection spectroscopy. Upon compression of the mixed monolayer AB211:DMPC = 1:5, a re-orientation of the chromophores from flat to tilted is observed, presumably assisted by the stretching of the choline group of the phospholipid molecules acting a matrix.

  15. Linear-g-hyperbranched and cyclodextrin-based amphiphilic block copolymer as a multifunctional nanocarrier.

    Science.gov (United States)

    Zhao, Yamei; Tian, Wei; Yang, Guang; Fan, Xiaodong

    2014-01-01

    In this paper, a novel, multifunctional polymer nanocarrier was designed to provide adequate volume for high drug loading, to afford a multiregion encapsulation ability, and to achieve controlled drug release. An amphiphilic, triblock polymer (ABC) with hyperbranched polycarbonsilane (HBPCSi) and β-cyclodextrin (β-CD) moieties were first synthesized by the combination of a two-step reversible addition-fragmentation transfer polymerization into a pseudo-one-step hydrosilylation and quaternization reaction. The ABC then self-assembled into stable micelles with a core-shell structure in aqueous solution. These resulting micelles are multifunctional nanocarriers which possess higher drug loading capability due to the introduction of HBPCSi segments and β-CD moieties, and exhibit controlled drug release based on the diffusion release mechanism. The novel multifunctional nanocarrier may be applicable to produce highly efficient and specialized delivery systems for drugs, genes, and diagnostic agents. PMID:25550733

  16. STUDIES ON SELF-ASSOCIATIVE BEHAVIOR OF A NOVEL CATION AMPHIPHILIC POLYMER

    Institute of Scientific and Technical Information of China (English)

    Jing Li; Fei-peng Wu; Er-jian Wang

    2009-01-01

    A novel associating polymer P(AEBA) was synthesized by radical polymerization of the cationic amphiphilic monomer, 4-(2-(acryloyloxy)ethoxy)benzyl tri-ethyl ammonium bromide (AEBA), in aqueous solutions. P(AEBA) displays a strong tendency for self-association in aqueous solutions and is sensitive to the external stimulation such as added salt. The associative properties and morphologies of P(AEBA) were studied by fluorescnece probe technique, viscometry and TEM. In dilute salt-free solutions P(AEBA) behaves as polyelectrolyte, while its behavior is similar to that of the polysoap as salt added. Accompanying increasing polymer concentration, polymer aggregation conformation changes from an extended necklace-like structure to a compact globular aggregate corresponding to the viscosity reduction.

  17. Molecular dynamics simulation of {beta}-sheet formation in self-assembled peptide amphiphile fibers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, One-Sun; Liu Yamei; Schatz, George C., E-mail: schatz@chem.northwestern.edu [Northwestern University, Department of Chemistry (United States)

    2012-08-15

    The influence of amino acid sequence on the secondary structure of peptide amphiphile (PAs) cylindrical micelles and fibers that are self-assembled in solution is studied using molecular dynamics simulations. Simulations for two choices of PAs were performed, starting with structures that have the correct overall shape, but which restructure considerably during the simulation, with one fiber being composed of valine rich PAs and the other of alanine rich PAs. Self-assembly is similar in both simulations, with stable fibers (diameter is 7.7-8 nm) obtained after 40 ns. We find that the valine rich PA fiber has a higher {beta}-sheet population than the alanine rich fiber, and that the number of hydrogen bonds is higher. This behavior of the valine rich fiber is consistent with experimental measurements of higher stiffness, and it shows that stiffness can be varied while still maintaining self-assembly.

  18. Surface-promoted aggregation of amphiphilic quadruplex ligands drives their selectivity for alternative DNA structures.

    Science.gov (United States)

    Laguerre, Aurélien; Chang, Yi; Pirrotta, Marc; Desbois, Nicolas; Gros, Claude P; Lesniewska, Eric; Monchaud, David

    2015-07-01

    Scientists are currently truly committed to enhance the specificity of chemotherapeutics that target DNA. To this end, sequence-specific drugs have progressively given way to structure-specific therapeutics. However, while numerous strategies have been implemented to design high-affinity candidates, strategies devoted to the design of high-selectivity ligands are still rare. Here we report on such an approach via the study of an amphiphilic compound, TEGPy, that self-assembles at a liquid/solid interface to provide nanosized objects that are stable in water. The resulting aggregates, identified through atomic force microscopy measurements, were found to disassemble upon interaction with DNA in a structure-specific manner (quadruplex- versus duplex-DNA). Our results provide a fertile ground for devising new strategies aiming at concomitantly enhancing DNA structural specificity and the water-solubility of aggregation-prone ligands. PMID:26040925

  19. Recent advances in amphiphilic polymers for simultaneous delivery of hydrophobic and hydrophilic drugs.

    Science.gov (United States)

    Martin, Chloe; Aibani, Noorjahan; Callan, John F; Callan, Bridgeen

    2016-01-01

    Nanomedicine has evolved with the use of biological compounds such as proteins, peptides and DNA. These hydrophilic and often highly charged compounds require a delivery system to allow effective transport and release at the site of action. These new biological therapeutics have not replaced the more traditional smaller molecule, but instead are working synergistically to the benefit of the end user. To that end, drug delivery systems are now required to encapsulate both larger hydrophilic compounds as well as the smaller and generally more hydrophobic compound. This review highlights the emerging role in drug delivery of amphiphilic polymers that by their very nature can associate with compounds of differing physicochemical properties, in particular the role of micelles, polymersomes and nanocapsules.

  20. Synthesis and characterization of amorphous mesoporous silica using TEMPO-functionalized amphiphilic templates

    Science.gov (United States)

    de Vries, Wilke; Doerenkamp, Carsten; Zeng, Zhaoyang; de Oliveira, Marcos; Niehaus, Oliver; Pöttgen, Rainer; Studer, Armido; Eckert, Hellmut

    2016-05-01

    Inorganic-organic hybrid materials based on amorphous mesoporous silica containing organized nitroxide radicals within its mesopores have been prepared using the micellar self-assembly of TEOS solutions containing the nitroxide functionalized amphiphile (4-(N,N-dimethyl-N-hexadecylammonium)-2,2,6,6-tetramethyl-piperidin-N-oxyl-iodide) (CAT-16). This template has been used both in its pure form and in various mixtures with cetyl trimethylammonium bromide (CTAB). The samples have been characterized by chemical analysis, N2 sorption studies, magnetic susceptibility measurements, and various spectroscopic methods. While electron paramagnetic resonance (EPR) spectra indicate that the strength of the intermolecular spin-spin interactions can be controlled via the CAT-16/CTAB ratio, nuclear magnetic resonance (NMR) data suggest that these interactions are too weak to facilitate cooperative magnetism.

  1. Accessible Mannitol-Based Amphiphiles (MNAs) for Membrane Protein Solubilisation and Stabilisation.

    Science.gov (United States)

    Hussain, Hazrat; Du, Yang; Scull, Nicola J; Mortensen, Jonas S; Tarrasch, Jeffrey; Bae, Hyoung Eun; Loland, Claus J; Byrne, Bernadette; Kobilka, Brian K; Chae, Pil Seok

    2016-05-17

    Integral membrane proteins are amphipathic molecules crucial for all cellular life. The structural study of these macromolecules starts with protein extraction from the native membranes, followed by purification and crystallisation. Detergents are essential tools for these processes, but detergent-solubilised membrane proteins often denature and aggregate, resulting in loss of both structure and function. In this study, a novel class of agents, designated mannitol-based amphiphiles (MNAs), were prepared and characterised for their ability to solubilise and stabilise membrane proteins. Some of MNAs conferred enhanced stability to four membrane proteins including a G protein-coupled receptor (GPCR), the β2 adrenergic receptor (β2 AR), compared to both n-dodecyl-d-maltoside (DDM) and the other MNAs. These agents were also better than DDM for electron microscopy analysis of the β2 AR. The ease of preparation together with the enhanced membrane protein stabilisation efficacy demonstrates the value of these agents for future membrane protein research. PMID:27072057

  2. Linear-g-hyperbranched and cyclodextrin-based amphiphilic block copolymer as a multifunctional nanocarrier

    Directory of Open Access Journals (Sweden)

    Yamei Zhao

    2014-11-01

    Full Text Available In this paper, a novel, multifunctional polymer nanocarrier was designed to provide adequate volume for high drug loading, to afford a multiregion encapsulation ability, and to achieve controlled drug release. An amphiphilic, triblock polymer (ABC with hyperbranched polycarbonsilane (HBPCSi and β-cyclodextrin (β-CD moieties were first synthesized by the combination of a two-step reversible addition-fragmentation transfer polymerization into a pseudo-one-step hydrosilylation and quaternization reaction. The ABC then self-assembled into stable micelles with a core–shell structure in aqueous solution. These resulting micelles are multifunctional nanocarriers which possess higher drug loading capability due to the introduction of HBPCSi segments and β-CD moieties, and exhibit controlled drug release based on the diffusion release mechanism. The novel multifunctional nanocarrier may be applicable to produce highly efficient and specialized delivery systems for drugs, genes, and diagnostic agents.

  3. Electrical release of dopamine and levodopa mediated by amphiphilic β-cyclodextrins immobilized on polycrystalline gold.

    Science.gov (United States)

    Foschi, Giulia; Leonardi, Francesca; Scala, Angela; Biscarini, Fabio; Kovtun, Alessandro; Liscio, Andrea; Mazzaglia, Antonino; Casalini, Stefano

    2015-12-21

    Vesicles of cationic amphiphilic β-cyclodextrins have been immobilized on polycrystalline gold by exploiting the chemical affinity between their amino groups and Au atoms. The presence of cyclodextrins has been widely investigated by means of AFM, XPS, kelvin probe and electrochemical measurements. This multi-functional coating confers distinct electrochemical features such as pH-dependent behavior and partial/total blocking properties towards electro-active species. The host-guest properties of β-cyclodextrins have been successfully exploited in order to trap drugs, like dopamine and levodopa. The further release of these drugs was successfully achieved by providing specific electrical stimuli. This proof-of-concept led us to fabricate an electronic device (i.e. an organic transistor) capable of dispensing both dopamine and levodopa in aqueous solution. PMID:26565988

  4. Cytocompatibility of Self-assembled Hydrogel from IKVAV-containing Peptide Amphiphile with Neural Stem Cells

    Institute of Scientific and Technical Information of China (English)

    SONG Yulin; ZHENG Qixin; GUO Xiaodong; ZHENG Jianfeng

    2009-01-01

    Neural Stem Cells(NSCs)were incubated with self-assembled hydrogel from IKVAV-containing peptide amphiphile(IKVAV-PA)for one week.The cytocompatibility of hydrogel was evaluated.NSCs were seeded in three-dimensional(3D)hydrogels(Experimental Group,EG)or surface of coverslips(Control Group,CG),double-labeled with Calcein-AM and PI.A growth curve of cells was obtained according to CCK-8.TEM study of hydrogel revealed a network of nanofibers. NSCs began to proliferate after 24 h of incubation,and formed bigger neurospheres at 48 h in EG than in CG.Cell proliferation activity was higher in EG than in CG(P<0.05).The self-assembled Hydrogel had good cytocompatibility and promoted the proliferation of NSCs.

  5. Salt Effect on the Cloud Point Phenomenon of Amphiphilic Drug-Hydroxypropylmethyl Cellulose System

    Directory of Open Access Journals (Sweden)

    Mohd. Sajid Ali

    2014-01-01

    Full Text Available Effect of two amphiphilic drugs (tricyclic antidepressant, nortriptyline hydrochloride (NORT, and nonsteroidal anti-inflammatory drug, sodium salt of ibuprofen (IBF on the cloud point of biopolymer hydroxypropylmethyl cellulose (HPMC was studied. Effect of NaCl was also seen on the CP of HPMC-drug system. CP of HPMC increases uniformly on increasing the (drug. Both drugs, though one being anionic (IBF and other cationic (NORT, affect the CP in almost the same manner but with different extent implying the role of hydrophobicity in the interaction between drug and polymer. Salt affects the CP of the drug in a dramatic way as low concentration of salt was only able to increase the value of the CP, though not affecting the pattern. However, in presence of high concentration of salts, minimum was observed on CP versus (drug plots. Various thermodynamic parameters were evaluated and discussed on the basis of the observed results.

  6. Electrical release of dopamine and levodopa mediated by amphiphilic β-cyclodextrins immobilized on polycrystalline gold

    Science.gov (United States)

    Foschi, Giulia; Leonardi, Francesca; Scala, Angela; Biscarini, Fabio; Kovtun, Alessandro; Liscio, Andrea; Mazzaglia, Antonino; Casalini, Stefano

    2015-11-01

    Vesicles of cationic amphiphilic β-cyclodextrins have been immobilized on polycrystalline gold by exploiting the chemical affinity between their amino groups and Au atoms. The presence of cyclodextrins has been widely investigated by means of AFM, XPS, kelvin probe and electrochemical measurements. This multi-functional coating confers distinct electrochemical features such as pH-dependent behavior and partial/total blocking properties towards electro-active species. The host-guest properties of β-cyclodextrins have been successfully exploited in order to trap drugs, like dopamine and levodopa. The further release of these drugs was successfully achieved by providing specific electrical stimuli. This proof-of-concept led us to fabricate an electronic device (i.e. an organic transistor) capable of dispensing both dopamine and levodopa in aqueous solution.Vesicles of cationic amphiphilic β-cyclodextrins have been immobilized on polycrystalline gold by exploiting the chemical affinity between their amino groups and Au atoms. The presence of cyclodextrins has been widely investigated by means of AFM, XPS, kelvin probe and electrochemical measurements. This multi-functional coating confers distinct electrochemical features such as pH-dependent behavior and partial/total blocking properties towards electro-active species. The host-guest properties of β-cyclodextrins have been successfully exploited in order to trap drugs, like dopamine and levodopa. The further release of these drugs was successfully achieved by providing specific electrical stimuli. This proof-of-concept led us to fabricate an electronic device (i.e. an organic transistor) capable of dispensing both dopamine and levodopa in aqueous solution. Electronic supplementary information (ESI) available: Kelvin probe, AFM and electrochemical data are reported. Furthermore, the chemical backbone of both types of cyclodextrins are shown. See DOI: 10.1039/c5nr05405b

  7. New renewable resource amphiphilic molecular design for size-controlled and highly ordered polyaniline nanofibers.

    Science.gov (United States)

    Anilkumar, P; Jayakannan, M

    2006-06-20

    We demonstrate here, for the first time, a unique strategy for conducting polyaniline nanofibers based on renewable resources. Naturally available cardanol, which is an industrial waste and main pollutant from the cashew nut industry, is utilized for producing well-defined polyaniline nanofibers. A new amphiphilic molecule is designed and developed from cardanol, which forms a stable emulsion with aniline for a wide composition range in water (1:1 to 1:100 dopant/aniline mole ratio) to produce polyaniline nanofibers. The scanning electron microscopy and transmission electron microscopy analysis of the nanofibers reveals that the dopant/aniline ratio plays a major role in determining the shape and size of polyaniline nanofibers. The nanofiber length increases with the increase in the dopant/aniline ratio, and perfectly linear, well-defined nanofibers of lengths as long as 7-8 muM were produced. The amphiphilic dopant has a built-in head-to-tail geometry and effectively penetrates into the polyaniline chains to form highly organized nanofibers. Wide-angle X-ray diffraction (WXRD) spectra of the nanofibers showed a new peak at 2theta = 6.3 (d spacing = 13.9 A) corresponding to the three-dimensional solid-state ordering of polyaniline-dopant chains, and this peak intensity increases with increase in the nanofiber length. The comparison of morphology and WXRD reveals that high ordering in polyaniline chains results in the formation of long, well-defined nanofibers, and this direct correlation for the polyaniline nanofibers with solid-state ordering has been established. The conductivity of the polyaniline nanofibers also increases with increase in the solid-state ordering rather than increasing with the extent of doping. The polyaniline nanofibers are freely soluble in water and possess high environmental and thermal stability up to 300 degrees C for various applications. PMID:16768535

  8. Terminal groups control self-assembly of amphiphilic block copolymers in solution

    Science.gov (United States)

    Grzelakowski, M.; Kita-Tokarczyk, K.

    2016-03-01

    The terminal groups of amphiphilic block copolymers are shown to control macromolecular self-assembly in aqueous solutions, in the micellar/lamellar region of the phase diagram. At the same concentration and using the same self-assembly conditions, dramatic differences are observed in polymer hydration and the resulting nano-/microstructure for two series of polymers with identical block chemistry and hydrophilic-lipophilic balance (HLB). This suggests a strong contribution from end groups to the hydration as the initial step of the self-assembly process, and could be conveniently used to guide the particle morphology and size. Additionally, for polymers with those head groups which drive vesicular structures, differences in membrane organization affect their physical properties, such as permeability.The terminal groups of amphiphilic block copolymers are shown to control macromolecular self-assembly in aqueous solutions, in the micellar/lamellar region of the phase diagram. At the same concentration and using the same self-assembly conditions, dramatic differences are observed in polymer hydration and the resulting nano-/microstructure for two series of polymers with identical block chemistry and hydrophilic-lipophilic balance (HLB). This suggests a strong contribution from end groups to the hydration as the initial step of the self-assembly process, and could be conveniently used to guide the particle morphology and size. Additionally, for polymers with those head groups which drive vesicular structures, differences in membrane organization affect their physical properties, such as permeability. Electronic supplementary information (ESI) available: Fig. S1: Particle diameters for hydrated NH2-ABA-NH2 polymers with different degrees of functionalization; Fig. S2: TEM characterization of compound micelles from BA-OH polymer after extrusion; Fig. S3: Cryo-TEM and stopped flow characterization of lipid vesicles; Fig. S4 and S5: NMR spectra for ABA and BA polymers

  9. Displacements of Backbone Vibrational Modes of Poly(U)·poly(A)·poly(U)%三链核酸poly(U)·poly(A)·poly(U)主链的振动位移

    Institute of Scientific and Technical Information of China (English)

    孟耀勇; 刘桂强; 刘颂豪

    2003-01-01

    基于三链核酸poly(U)·poly(A)·poly(U)的螺旋对称性,利用晶格动力学方法,计算了三链核酸分子poly(U)·poly(A)·poly(U)主链振动的本征矢,探讨了振动位移矢量和线二色光谱的关系.结果表明,对应着磷酸双氧的反对称振动谱线可以用于直接确定磷酸根的取向,精度大约为1°.其他谱线必须通过对分子的简正分析来帮助确定分子的结构.

  10. Lactosylated poly(ethylene oxide)-poly(propylene oxide) block copolymers for potential active targeting: synthesis and physicochemical and self-aggregation characterization

    Energy Technology Data Exchange (ETDEWEB)

    Cuestas, Maria L.; Glisoni, Romina J. [University of Buenos Aires, Group of Biomaterials and Nanotechnology for Improved Medicines (BIONIMED), Department of Pharmaceutical Technology, Faculty of Pharmacy and Biochemistry (Argentina); Mathet, Veronica L. [National Science Research Council (CONICET) (Argentina); Sosnik, Alejandro, E-mail: alesosnik@gmail.com [University of Buenos Aires, The Group of Biomaterials and Nanotechnology for Improved Medicines (BIONIMED), Department of Pharmaceutical Technology, Faculty of Pharmacy and Biochemistry (Argentina)

    2013-01-15

    Aiming to develop polymeric self-assembly nanocarriers with potential applications in active drug targeting to the liver, linear and branched poly(ethylene oxide)-poly(propylene oxide) amphiphiles were conjugated to lactobionic acid (LA), a disaccharide of galactose and gluconic acid, by the conventional Steglich esterification reaction. The conjugation was confirmed by ATR/FT-IR, {sup 1}H-NMR, and {sup 13}C-NMR spectroscopy. Elemental analysis and MALDI-TOF mass spectrometry were employed to elucidate the conjugation extent and the final molecular weight, respectively. The critical micellar concentration (CMC), the size and size distribution and zeta potential of the pristine and modified polymeric micelles under different conditions of pH and temperature were characterized by dynamic light scattering (DLS). Conjugation with LA favored the micellization process, leading to a decrease of the CMC with respect to the pristine counterpart, this phenomenon being independent of the pH and the temperature. At 37 Degree-Sign C, micelles made of pristine copolymers showed a monomodal size distribution between 12.8 and 24.4 nm. Conversely, LA-conjugated micelles showed a bimodal size pattern that comprised a main fraction of relatively small size (11.6-22.2 nm) and a second one with remarkably larger sizes of up to 941.4 nm. The former corresponded to single micelles, while the latter would indicate a secondary aggregation phenomenon. The spherical morphology of LA-micelles was visualized by transmission electron microscopy (TEM). Finally, to assess the ability of the LA-conjugated micelles to interact with lectin-like receptors, samples were incubated with concanavalin A at 37 Degree-Sign C and the size and size distribution were monitored by DLS. Findings indicated that regardless of the relatively weak affinity of this vegetal lectin for galactose, micelles underwent agglutination probably through the interaction of a secondary site in the lectin with the gluconic acid

  11. Tipping the scale from disorder to alpha-helix: Folding of amphiphilic peptides in the presence of macroscopic and molecular interfaces

    OpenAIRE

    Dalgıçdır, Cahit; Sayar, Mehmet; Globisch, Christoph; Peter, Christine

    2015-01-01

    Secondary amphiphilicity is inherent to the secondary structural elements of proteins. By forming energetically favorable contacts with each other these amphiphilic building blocks give rise to the formation of a tertiary structure. Small proteins and peptides, on the other hand, are usually too short to form multiple structural elements and cannot stabilize them internally. Therefore, these molecules are often found to be structurally ambiguous up to the point of a large degree of intrinsic ...

  12. Synthesis of novel 1,4-dihydropyridine and 3,4-dihydropyridone based fluorous cationic amphiphiles for possible transmembrane delivery applications

    OpenAIRE

    Šmits, Rufs

    2012-01-01

    ABSTRACT Synthesis of novel 1,4-dihydropyridine and 3,4-dihydropyridone based fluorous cationic amphiphiles for possible transmembrane delivery applications. Smits R., Dr. Chem. Prof. G.W. Buchanan, Dr. Chem. Vigante B., Doctor’s Thesis , 163 pages, 48 figures, 54 schemes, 6 tables, 266 references. In English language. 1,4-DIHYDROPYRIDINE, 3,4-DIHYDROPYRIDONE, FLUOROUS ESTERS, CATIONIC AMPHIPHILES, DNA TRANSFECTION, DRUG DELIVERY, BROMINATION, OXIDATION, CHLORO-FORMYLATION, HYDROGEN BON...

  13. The amphiphilic nature of saponins and their effects on artificial and biological membranes and potential consequences for red blood and cancer cells

    OpenAIRE

    Lorent, Joseph H.; Quetin-Leclercq, Joëlle; Mingeot-Leclercq, Marie-Paule

    2014-01-01

    Saponins, amphiphiles of natural origin with numerous biological activities, are widely used in the cosmetic and pharmaceutical industry. Some saponins exhibit relatively selective cytotoxic effects on cancer cells but the tendency of saponins to induce hemolysis limits their anticancer potential. This review focused on the effects of saponin activity on membranes and consequent implications for red blood and cancer cells. This activity seems to be strongly related to the amphiphilic characte...

  14. Spontaneous Polymerization of An Amino Acid Based Amphiphile at Air/water Interface Investigated by ESI-MS and Transmission IR Spectrometry

    Institute of Scientific and Technical Information of China (English)

    WANG Hai-Yan; XIAO Yi; LI Yan-Mei; WU Li-Xin; YU Zhi-Wu; ZHAO Yu-Fen

    2003-01-01

    @@ Self-assemblies of amphiphilic molecules are proposed to play a ubiquitous role at the early stages of evolution in the formation of primitive biopolymers. [1] As regard to the significance of N-phosphoryl amino acids as a model for the co-evolution of protein and nucleic acids at the prebiotic stage, [2] amphiphilic N-phosphoryl amino acids with two hydrophobic tails were synthesized. [3

  15. 三螺旋DNA分子Poly(dT)·Poly(dA)·Poly(dT)碱基振动模式%The Base Vibrational Modes of Poly(dT)*Poly(dA)*Poly(dT)

    Institute of Scientific and Technical Information of China (English)

    孟耀勇

    2001-01-01

    利用晶格动力学方法计算了三螺旋DNA分子poly(dT)*poly(dA)*poly(dT)碱基振动模式,并根据势能分布矩阵对碱基振动模式进行了指定.计算的模式频率同拉曼光谱实验相符合.

  16. Transdisciplinary Research in Social Polis

    OpenAIRE

    Cassinari, Davide; Moulaert, Frank; Hillier, Jean; novy, andreas; Miciukiewicz, Konrad; habersack, Sarah; MacCallum, diana

    2011-01-01

    This paper discusses the trandisciplinary methodology which was applied in the European Platform Social Polis. Transdisciplinary research involves different types of actors, ranging from academic researchers to day-to-day users of particular opportunities in society. It requires specific governance that mobilises different types of knowledge to identify relevant societal problems and to contribute to their solution. Trandisciplinary methodology, therefore, is a research strategy that crosses ...

  17. Ga(III) chelates of amphiphilic DOTA-based ligands: synthetic route and in vitro and in vivo studies

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, Andre [Centro de Quimica, Campus de Gualtar, Universidade do Minho, 4710-057, Braga (Portugal); Prata, M. Isabel M. [IBILI, Faculdade de Medicina, Universidade de Coimbra, 3548, Coimbra (Portugal); Geraldes, Carlos F.G.C. [Departamento de Ciencias da Vida, Faculdade de Ciencias e Tecnologia, Universidade de Coimbra, 3001-401, Coimbra (Portugal); Centro de Neurociencias e Biologia Celular, Universidade de Coimbra, 3001-401, Coimbra (Portugal); Andre, Joao P., E-mail: jandre@quimica.uminho.p [Centro de Quimica, Campus de Gualtar, Universidade do Minho, 4710-057, Braga (Portugal)

    2011-04-15

    In this work, we report on a synthetic strategy using amphiphilic DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)-based chelators bearing a variable-sized {alpha}-alkyl chain at one of the pendant acetate arms (from 6 to 14 carbon atoms), compatible with their covalent coupling to amine-bearing biomolecules. The amphiphilic behavior of the micelles-forming Ga(III) chelates (critical micellar concentration), their stability in blood serum and their lipophilicity (logP) were investigated. Biodistribution studies with the {sup 67}Ga-labeled chelates were performed in Wistar rats, which showed a predominant liver uptake with almost no traces of the radiochelates in the body after 24 h.

  18. Graphene oxide-enhanced sol-gel transition sensitivity and drug release performance of an amphiphilic copolymer-based nanocomposite

    Science.gov (United States)

    Hu, Huawen; Wang, Xiaowen; Lee, Ka I.; Ma, Kaikai; Hu, Hong; Xin, John H.

    2016-08-01

    We report the fabrication of a highly sensitive amphiphilic copolymer-based nanocomposite incorporating with graphene oxide (GO), which exhibited a low-intensity UV light-triggered sol-gel transition. Non-cytotoxicity was observed for the composite gels after the GO incorporation. Of particular interest were the microchannels that were formed spontaneously within the GO-incorporated UV-gel, which expedited sustained drug release. Therefore, the present highly UV-sensitive, non-cytotoxic amphiphilic copolymer-based composites is expected to provide enhanced photothermal therapy and chemotherapy by means of GO’s unique photothermal properties, as well as through efficient passive targeting resulting from the sol-gel transition characteristic of the copolymer-based system with improved sensitivity, which thus promises the enhanced treatment of patients with cancer and other diseases.

  19. A redox-responsive mesoporous silica nanoparticle capped with amphiphilic peptides by self-assembly for cancer targeting drug delivery

    Science.gov (United States)

    Xiao, Dong; Jia, Hui-Zhen; Ma, Ning; Zhuo, Ren-Xi; Zhang, Xian-Zheng

    2015-05-01

    A redox-responsive mesoporous silica nanoparticle (RRMSN) was developed as a drug nanocarrier by noncovalent functionalization of MSNs with amphiphilic peptides containing the RGD ligand. The alkyl chain stearic acid (C18) with a thiol terminal group was anchored on the surface of MSNs via a disulfide bond, and the amphiphilic peptide (AP) C18-DSDSDSDSRGDS was coated by self-assembly through hydrophobic interactions between the octadecyl groups of MSNs and alkyl chains of AP, which played the role of a gatekeeper collectively. In vitro drug release profiles demonstrated that the anticancer drug (DOX) could be entrapped with nearly no leakage in the absence of dithiothreitol (DTT) or glutathione (GSH). With the addition of DTT or GSH, the entrapped drug released quickly due to the cleavage of the disulfide bond. It was found that after the internalization of MSNs by cancer cells via the receptor-mediated endocytosis, the surface amphiphilic peptides and alkyl chain of RRMSN/DOX were removed to induce rapid drug release intracellularly after the cleavage of the disulfide bond, triggered by GSH secreted in cancer cells. This novel intelligent RRMSN/DOX drug delivery system using self-assembly of amphiphilic peptides around the MSNs provides a facile, but effective strategy for the design and development of smart drug delivery for cancer therapy.A redox-responsive mesoporous silica nanoparticle (RRMSN) was developed as a drug nanocarrier by noncovalent functionalization of MSNs with amphiphilic peptides containing the RGD ligand. The alkyl chain stearic acid (C18) with a thiol terminal group was anchored on the surface of MSNs via a disulfide bond, and the amphiphilic peptide (AP) C18-DSDSDSDSRGDS was coated by self-assembly through hydrophobic interactions between the octadecyl groups of MSNs and alkyl chains of AP, which played the role of a gatekeeper collectively. In vitro drug release profiles demonstrated that the anticancer drug (DOX) could be entrapped with

  20. Graphene oxide-enhanced sol-gel transition sensitivity and drug release performance of an amphiphilic copolymer-based nanocomposite

    Science.gov (United States)

    Hu, Huawen; Wang, Xiaowen; Lee, Ka I; Ma, Kaikai; Hu, Hong; Xin, John H.

    2016-01-01

    We report the fabrication of a highly sensitive amphiphilic copolymer-based nanocomposite incorporating with graphene oxide (GO), which exhibited a low-intensity UV light-triggered sol-gel transition. Non-cytotoxicity was observed for the composite gels after the GO incorporation. Of particular interest were the microchannels that were formed spontaneously within the GO-incorporated UV-gel, which expedited sustained drug release. Therefore, the present highly UV-sensitive, non-cytotoxic amphiphilic copolymer-based composites is expected to provide enhanced photothermal therapy and chemotherapy by means of GO’s unique photothermal properties, as well as through efficient passive targeting resulting from the sol-gel transition characteristic of the copolymer-based system with improved sensitivity, which thus promises the enhanced treatment of patients with cancer and other diseases. PMID:27539298

  1. Tubular Structures Self-Assembled from a Bola-Amphiphilic Pillar[5]arene in Water and Applied as a Microreactor.

    Science.gov (United States)

    Chen, Rener; Jiang, Huajiang; Gu, Haining; Zhou, Qizhong; Zhang, Zhen; Wu, Jiashou; Jin, Zhengneng

    2015-09-01

    Various nanomorphologies were obtained by simply changing the fabrication conditions, such as the pH of the system, different solvent, or different concentration, of bola-amphiphilic pillar[5]arene Bola-AP5. Importantly, hybrid microtubules as a microreactor were successfully prepared by directly reducing AuCl4(-) on the surface of Bola-AP5-based tubular structures in water. PMID:26275020

  2. Nano-Assemblies of Modified Cyclodextrins and Their Complexes with Guest Molecules: Incorporation in Nanostructured Membranes and Amphiphile Nanoarchitectonics Design

    OpenAIRE

    Leïla Zerkoune; Angelina Angelova; Sylviane Lesieur

    2014-01-01

    A variety of cyclodextrin-based molecular structures, with substitutions of either primary or secondary faces of the natural oligosaccharide macrocycles of α-, β-, or γ-cyclodextrins, have been designed towards innovative applications of self-assembled cyclodextrin nanomaterials. Amphiphilic cyclodextrins have been obtained by chemical or enzymatic modifications of their macrocycles using phospholipidyl, peptidolipidyl, cholesteryl, and oligo(ethylene oxide) anchors as well as variable numb...

  3. New amphiphilic glycopolypeptide conjugate capable of self-assembly in water into reduction-sensitive micelles for triggered drug release

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hui-Kang [DSAPM Lab and PCFM Lab, Department of Polymer and Materials Science, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Zhang, Li-Ming, E-mail: ceszhlm@mail.sysu.edu.cn [DSAPM Lab and PCFM Lab, Department of Polymer and Materials Science, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Science, Sun Yat-sen University, Guangzhou 510006 (China)

    2014-08-01

    For the development of biomimetic carriers for stimuli-sensitive delivery of anticancer drugs, a novel amphiphilic glycopolypeptide conjugate containing the disulfide bond was prepared for the first time by the ring-opening polymerization of benzyl glutamate N-carboxy anhydride in the presence of (propargyl carbamate)ethyl dithio ethylamine and then click conjugation with α-azido dextran. Its structure was characterized by Fourier-transform infrared spectroscopy and nuclear magnetic resonance analyses. Owing to its amphiphilic nature, such a conjugate could self assemble into nanosize micelles in aqueous medium, as confirmed by fluorometry, transmission electron microscopy and dynamic light scattering. For the resultant micelles, it was found to encapsulate poorly water-soluble anticancer drug (methotrexate, MTX) with the loading efficiency of 45.2%. By the in vitro drug release tests, the release rate of encapsulated MTX was observed to be accelerated significantly in the presence of 10 mM 1,4-dithio-DL-threitol (DTT), analogous to the intracellular redox potential. - Graphical abstract: New amphiphilic glycopolypeptide conjugate containing the disulfide bond could self-assemble in aqueous solution into reduction-sensitive micelles for triggered release of an anticancer drug (methotrexate, MTX) in the presence of 10 mM 1,4-dithio-DL-threitol (DTT). - Highlights: • Amphiphilic glycopolypeptide conjugate containing disulfide bond was prepared. • Such a conjugate self assembled in aqueous solution into nanosize micelles. • The resultant micelles could encapsulate effectively methotrexate drug. • The drug-loaded micelles showed a reduction-sensitive drug release behavior.

  4. Nucleobases bind to and stabilize aggregates of a prebiotic amphiphile, providing a viable mechanism for the emergence of protocells

    OpenAIRE

    Black, RA; Blosser, MC; Stottrup, BL; Tavakley, R; Deamer, DW; Keller, SL

    2013-01-01

    Primordial cells presumably combined RNAs, which functioned as catalysts and carriers of genetic information, with an encapsulating membrane of aggregated amphiphilic molecules. Major questions regarding this hypothesis include how the four bases and the sugar in RNA were selected from a mixture of prebiotic compounds and colocalized with such membranes, and how the membranes were stabilized against flocculation in salt water. To address these questions, we explored the possibility that aggre...

  5. New amphiphilic glycopolypeptide conjugate capable of self-assembly in water into reduction-sensitive micelles for triggered drug release

    International Nuclear Information System (INIS)

    For the development of biomimetic carriers for stimuli-sensitive delivery of anticancer drugs, a novel amphiphilic glycopolypeptide conjugate containing the disulfide bond was prepared for the first time by the ring-opening polymerization of benzyl glutamate N-carboxy anhydride in the presence of (propargyl carbamate)ethyl dithio ethylamine and then click conjugation with α-azido dextran. Its structure was characterized by Fourier-transform infrared spectroscopy and nuclear magnetic resonance analyses. Owing to its amphiphilic nature, such a conjugate could self assemble into nanosize micelles in aqueous medium, as confirmed by fluorometry, transmission electron microscopy and dynamic light scattering. For the resultant micelles, it was found to encapsulate poorly water-soluble anticancer drug (methotrexate, MTX) with the loading efficiency of 45.2%. By the in vitro drug release tests, the release rate of encapsulated MTX was observed to be accelerated significantly in the presence of 10 mM 1,4-dithio-DL-threitol (DTT), analogous to the intracellular redox potential. - Graphical abstract: New amphiphilic glycopolypeptide conjugate containing the disulfide bond could self-assemble in aqueous solution into reduction-sensitive micelles for triggered release of an anticancer drug (methotrexate, MTX) in the presence of 10 mM 1,4-dithio-DL-threitol (DTT). - Highlights: • Amphiphilic glycopolypeptide conjugate containing disulfide bond was prepared. • Such a conjugate self assembled in aqueous solution into nanosize micelles. • The resultant micelles could encapsulate effectively methotrexate drug. • The drug-loaded micelles showed a reduction-sensitive drug release behavior

  6. A molecular model for membrane fusion based on solution studies of an amphiphilic peptide from HIV gp41.

    OpenAIRE

    Fujii, G; Horvath, S.; Woodward, S.; Eiserling, F.; Eisenberg, D.

    1992-01-01

    The mechanism of protein-mediated membrane fusion and lysis has been investigated by solution-state studies of the effects of peptides on liposomes. A peptide (SI) corresponding to a highly amphiphilic C-terminal segment from the envelope protein (gp41) of the human immunodeficiency virus (HIV) was synthesized and tested for its ability to cause lipid membranes to fuse together (fusion) or to break open (lysis). These effects were compared to those produced by the lytic and fusogenic peptide ...

  7. One-Pot Synthesis, Encaspulation, and Solubilization of Size-Tuned Quantum Dots with Amphiphilic Multidentate Ligands

    OpenAIRE

    Kairdolf, Brad A.; SMITH, ANDREW M.; Nie, Shuming

    2008-01-01

    We report one-pot synthesis, encapsulation, and solubilization of high-quality quantum dots based on the use of amphiphilic and multidentate polymer ligands. In this “all-in-one” procedure, the resulting QDs are first capped by the multidentate ligand, and are then spontaneously encapsulated and solubilized by a second layer of the same multidentate polymer upon exposure to water. In addition to providing better control of nanocrystal nucleation and growth kinetics (including resistance to Os...

  8. Analysis of the aggregation structure from amphiphilic block copolymers in solutions by small-angle x-ray scattering

    CERN Document Server

    Rong Li Xia; Wang Jun; Wei Liu He; Li Fu Mian; Li Zi Chen

    2002-01-01

    The aggregation structure of polystyrene-p vinyl benzoic amphiphilic block copolymers which were prepared in different conditions was investigated by synchrotron radiation small-angle x-ray scattering (SAXS). The micelle was self-assembled in selective solvents of the block copolymers. Authors' results demonstrate that the structure of the micelle depends on the factors, such as the composition of the copolymers, the nature of the solvent and the concentration of the solution

  9. Self-assembled micelles of amphiphilic PEGylated rapamycin for loading paclitaxel and resisting multidrug resistance cancer cells

    OpenAIRE

    W. Tian; Liu, J; Guo, Y; Shen, Y.; D. Zhou; Guo, S.

    2015-01-01

    Self-assembled micelles of amphiphilic PEG–rapamycin conjugates loaded with paclitaxel have been developed for co-delivery and simultaneous intracellular release of paclitaxel and rapamycin, bypassing the cancer cell drug resistant mechanism and maximising the synergy of dual-drug combinational therapy. This novel nanomedicine offers 20-fold improved potency over free paclitaxel against a model multidrug resistant human breast cancer cell.

  10. Synthesis and Self-Assembly of a Mikto-Arm Star Dual Drug Amphiphile Containing both Paclitaxel and Camptothecin

    OpenAIRE

    Cheetham, A.G.; Zhang, P.; Lin, Y.-A; Lin, R; Cui, H

    2014-01-01

    Self-assembly of anticancer therapeutics into discrete nanostructures provides an innovative way to develop a self-delivering nanomedicine with a high, quantitative drug loading. We report here the synthesis and assembly of a mikto-arm star dual drug amphiphile (DA) containing both a bulky paclitaxel (PTX) and a planar camptothecin (CPT). The two anti-cancer drugs of interest were stochastically conjugated to a β-sheet forming peptide (Sup35) and under physiologically-relevant conditions the ...

  11. Synthesis and Phase Behavior of Poly(N-isopropylacrylamide-b- Poly(L-Lysine Hydrochloride and Poly(N-Isopropylacrylamide- co-Acrylamide-b-Poly(L-Lysine Hydrochloride

    Directory of Open Access Journals (Sweden)

    Milica Spasojević

    2014-07-01

    Full Text Available The synthesis of poly(N-isopropylacrylamide-b-poly(L-lysine and poly(N- isopropylacrylamide-co-acrylamide-b-poly(L-lysine copolymers was accomplished by combining atom transfer radical polymerization (ATRP and ring opening polymerization (ROP. For this purpose, a di-functional initiator with protected amino group was successfully synthetized. The ATRP of N-isopropylacrylamide yielded narrowly dispersed polymers with consistent high yields (~80%. Lower yields (~50% were observed when narrowly dispersed random copolymers of N-isopropylacrylamide and acrylamide where synthesized. Amino-terminated poly(N-isopropylacrylamide and poly(N-isopropylacrylamide- co-acrylamide were successfully used as macroinitiators for ROP of N6-carbobenzoxy-L- lysine N-carboxyanhydride. The thermal behavior of the homopolymers and copolymers in aqueous solutions was studied by turbidimetry, dynamic light scattering (DLS and proton nuclear magnetic resonance spectroscopy (1H-NMR.

  12. Shape Modification of Water-in-CO2 Microemulsion Droplets through Mixing of Hydrocarbon and Fluorocarbon Amphiphiles.

    Science.gov (United States)

    Yan, Ci; Sagisaka, Masanobu; Rogers, Sarah E; Hazell, Gavin; Peach, Jocelyn; Eastoe, Julian

    2016-02-16

    An oxygen-rich hydrocarbon (HC) amphiphile has been developed as an additive for supercritical CO2 (scCO2). The effects of this custom-designed amphiphile have been studied in water-in-CO2 (w/c) microemulsions stabilized by analogous fluorocarbon (FC) surfactants, nFG(EO)2, which are known to form spherical w/c microemulsion droplets. By applying contrast-variation small-angle neutron scattering (CV-SANS), evidence has been obtained for anisotropic structures in the mixed systems. The shape transition is attributed to the hydrocarbon additive, which modifies the curvature of the mixed surfactant films. This can be considered as a potential method to enhance physicochemical properties of scCO2 through elongation of w/c microemulsion droplets. More importantly, by studying self-assembly in these mixed systems, fundamental understanding can be developed on the packing of HC and FC amphiphiles at water/CO2 interfaces. This provides guidelines for the design of fluorine-free CO2 active surfactants, and therefore, practical industrial scale applications of scCO2 could be achieved. PMID:26807476

  13. Nano-Assemblies of Modified Cyclodextrins and Their Complexes with Guest Molecules: Incorporation in Nanostructured Membranes and Amphiphile Nanoarchitectonics Design

    Directory of Open Access Journals (Sweden)

    Leïla Zerkoune

    2014-08-01

    Full Text Available A variety of cyclodextrin-based molecular structures, with substitutions of either primary or secondary faces of the natural oligosaccharide macrocycles of α-, β-, or γ-cyclodextrins, have been designed towards innovative applications of self-assembled cyclodextrin nanomaterials. Amphiphilic cyclodextrins have been obtained by chemical or enzymatic modifications of their macrocycles using phospholipidyl, peptidolipidyl, cholesteryl, and oligo(ethylene oxide anchors as well as variable numbers of grafted hydrophobic hydrocarbon or fluorinated chains. These novel compounds may self-assemble in an aqueous medium into different types of supramolecular nanoassemblies (vesicles, micelles, nanorods, nanospheres, and other kinds of nanoparticles and liquid crystalline structures. This review discusses the supramolecular nanoarchitectures, which can be formed by amphiphilic cyclodextrin derivatives in mixtures with other molecules (phospholipids, surfactants, and olygonucleotides. Biomedical applications are foreseen for nanoencapsulation of drug molecules in the hydrophobic interchain volumes and nanocavities of the amphiphilic cyclodextrins (serving as drug carriers or pharmaceutical excipients, anticancer phototherapy, gene delivery, as well as for protection of instable active ingredients through inclusion complexation in nanostructured media.

  14. Nucleobases bind to and stabilize aggregates of a prebiotic amphiphile, providing a viable mechanism for the emergence of protocells.

    Science.gov (United States)

    Black, Roy A; Blosser, Matthew C; Stottrup, Benjamin L; Tavakley, Ravi; Deamer, David W; Keller, Sarah L

    2013-08-13

    Primordial cells presumably combined RNAs, which functioned as catalysts and carriers of genetic information, with an encapsulating membrane of aggregated amphiphilic molecules. Major questions regarding this hypothesis include how the four bases and the sugar in RNA were selected from a mixture of prebiotic compounds and colocalized with such membranes, and how the membranes were stabilized against flocculation in salt water. To address these questions, we explored the possibility that aggregates of decanoic acid, a prebiotic amphiphile, interact with the bases and sugar found in RNA. We found that these bases, as well as some but not all related bases, bind to decanoic acid aggregates. Moreover, both the bases and ribose inhibit flocculation of decanoic acid by salt. The extent of inhibition by the bases correlates with the extent of their binding, and ribose inhibits to a greater extent than three similar sugars. Finally, the stabilizing effects of a base and ribose are additive. Thus, aggregates of a prebiotic amphiphile bind certain heterocyclic bases and sugars, including those found in RNA, and this binding stabilizes the aggregates against salt. These mutually reinforcing mechanisms might have driven the emergence of protocells. PMID:23901105

  15. Formation of size-controlled, denaturation-resistant lipid nanodiscs by an amphiphilic self-polymerizing peptide.

    Science.gov (United States)

    Kondo, Hiroaki; Ikeda, Keisuke; Nakano, Minoru

    2016-10-01

    Nanodiscs are discoidal particles with a planar phospholipid bilayer enwrapped by proteins such as apolipoprotein A-I. Nanodiscs have been widely used for analyzing structures and functions of membrane proteins by dispersing them in solution. They are expected to be used as drug carriers and therapeutic agents. Amphiphilic peptides are known to form nanodiscs. However, the lipid-peptide nanodiscs are relatively unstable in solution, making them unsuitable for many applications. Here, we report the synthesis of an amphiphilic self-polymerizing peptide termed ASPP1, which polymerizes by intermolecular native chemical ligation reactions. ASPP1 spontaneously formed nanodiscs when added to phospholipid vesicles without using detergents. The diameter of the planar lipid bilayer in the nanodiscs was controlled by the lipid:peptide molar ratio. ASPP1-nanodiscs exhibited greater stability at high temperatures or in the presence of urea than nanodiscs formed by the non-polymerizing amphiphilic peptide or apolipoprotein A-I. Average and maximal degrees of ASPP1 polymerization were 2.4 and 12, respectively. Self-polymerization of the peptide appears to be responsible for stabilization of the nanodiscs. Our results open a new avenue for the development of nanodisc technology. PMID:27393815

  16. A Comprehensive Study on Lyotropic Liquid-Crystalline Behavior of an Amphiphile in 20 Kinds of Amino Acid Ionic Liquids.

    Science.gov (United States)

    Fujimura, Kanae; Ichikawa, Takahiro; Yoshio, Masafumi; Kato, Takashi; Ohno, Hiroyuki

    2016-02-18

    We examined the self-organization behavior of a designed amphiphilic molecule in 20 kinds of amino acid ionic liquids composed of 1-butyl-3-methylimidazolium cation and natural amino acid anion ([C4mim][AA]). Addition of [C4mim][AA], regardless of their anion species, to the amphiphile provided homogeneous mixtures showing lyotropic liquid-crystalline (LC) behavior. Upon increasing the component ratio of [C4mim][AA] in the mixtures, a successive change of the mesophase patterns from inverted hexagonal columnar, in some case via bicontinuous cubic, to layered phases was observed. By examining the LC properties at various temperatures and component ratios, we constructed lyotropic LC phase diagrams. Interestingly, the appearance of these phase diagrams is greatly different according to the selection of [AA]. Through comparison, we found that the self-organization behavior of an amphiphile in ionic liquids can be tuned by controlling their ability to form hydrogen-bond, van der Waals, and π-π interactions.

  17. Self-Assembly of Amphiphilic Block Copolypeptoids with C 2 -C 5 Side Chains in Aqueous Solution

    KAUST Repository

    Fetsch, Corinna

    2014-12-22

    © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Nowadays, amphiphilic molecules play an important role in our life. In medical applications, amphiphilic block copolymers have attracted much attention as excipients in drug delivery systems. Here, the polymers are used as emulsifiers, micelles, or polymersomes with a hydrophilic corona block and a hydrophobic core or membrane. The aggregation behavior in aqueous solutions of a series of different amphiphilic block copolypeptoids comprising polysarcosine as a hydrophilic part is here reported. The formation of aggregates is investigated with 1H NMR spectroscopy and dynamic light scattering, and the determination of the critical micelle concentration (cmc) is performed using pyrene fluorescence spectroscopy. For the different block copolypeptoids cmc values ranging from 0.6 × 10-6 M to 0.1 × 10-3 M are found. The tendency to form micelles increases with increasing hydrophobicity at the nitrogen side chain in the hydrophobic moiety. Furthermore, in the case of the same hydrophobic side chain, a decreasing hydrophilic/lipophilic balance leads to the formation of larger aggregates. The aggregates formed in the buffer are able to solubilize the hydrophobic model compounds Reichardt\\'s dye and pyrene, and exhibit versatile microenvironments. Final investigations about the cytotoxicity reveal that the block copolypeptoids are well tolerated by mammalian cells up to high concentrations.

  18. Hydrophobic Effect of Amphiphilic Derivatives of Chitosan on the Antifungal Activity against Aspergillus flavus and Aspergillus parasiticus

    Directory of Open Access Journals (Sweden)

    Vera Ap. de Oliveira Tiera

    2013-04-01

    Full Text Available Low molecular weight amphiphilic derivatives of chitosan were synthesized, characterized and their antifungal activities against Aspergillus flavus and Aspergillus parasiticus were tested. The derivatives were synthesized using as starting material a deacetylated chitosan sample in a two step process: the reaction with propyltrimethyl-ammonium bromide (Pr, followed by reductive amination with dodecyl aldehyde. Aiming to evaluate the effect of the hydrophobic modification of the derivatives on the antifungal activity against the pathogens, the degree of substitution (DS1 by Pr groups was kept constant and the proportion of dodecyl (Dod groups was varied from 7 to 29% (DS2. The derivatives were characterized by 1H-NMR and FTIR and their antifungal activities against the pathogens were tested by the radial growth of the colony and minimum inhibitory concentration (MIC methods. The derivatives substituted with only Pr groups exhibited modest inhibition against A. flavus and A. parasiticus, like that obtained with deacetylated chitosan. Results revealed that the amphiphilic derivatives grafted with Dod groups exhibited increasing inhibition indexes, depending on polymer concentration and hydrophobic content. At 0.6 g/L, all amphiphilic derivatives having from 7.0 to 29% of Dod groups completely inhibited fungal growth and the MIC values were found to decrease from 4.0 g/L for deacetylated chitosan to 0.25–0.50 g/L for the derivatives. These new derivatives open up the possibility of new applications and avenues to develop effective biofungicides based on chitosan.

  19. Preparation of POSS-poly(ɛ-caprolactone)-β-cyclodextrin/Fe3O4 hybrid magnetic micelles for removal of bisphenol A from water.

    Science.gov (United States)

    Yuan, Weizhong; Shen, Jin; Li, Lulin; Liu, Xu; Zou, Hui

    2014-11-26

    A novel amphiphilic star-shaped inorganic-organic hybrid copolymer polyhedral oligomeric silsesquioxane-poly(ɛ-caprolactone)-β-cyclodextrin (POSS-PCL-β-CD) was synthesized by ring-opening polymerization (ROP) and click chemistry. The amphiphilic copolymer can self-assemble into hybrid micelles with hydrophobic POSS-PCL chain encapsulating Fe3O4 nanoparticles as the core and β-CD as the shell after mixing with Fe3O4 nanoparticles in solvent and dialysis against water. The chemical structure of POSS-PCL-β-CD was characterized by (1)H NMR and the morphology of the magnetic hybrid micelles was characterized by TEM and DLS. Due to the host-guest interaction of β-CD with bisphenol A (BPA), POSS-PCL-β-CD/Fe3O4 hybrid micelles present good adsorption capacity in removal of BPA from aqueous solution. Magnetic measurement reveals that POSS-PCL-β-CD/Fe3O4 hybrid micelles still exhibit magnetism for separation by an external magnetic field, indicating that these magnetic hybrid micelles may have potential application in the field of environmental protection. PMID:25256494

  20. Preparation of hydrophilic poly(lactic acid) tissue engineering scaffold via (PLA)-(PLA-b-PEG)-(PEG) solution casting and thermal-induced surface structural transformation.

    Science.gov (United States)

    Zhu, Xiaomin; Zhong, Tian; Huang, Ran; Wan, Ajun

    2015-01-01

    Porous poly(lactic acid) (PLA) tissue engineering scaffolds with a hydrophilic surface assembled by polyethylene glycol aggregations were prepared by the solvent casting/particulate leaching method from (PLA)-(PLA-b-PEG)-(PEG) blend solution, where the PLA-b-PEG block polymer serves as an amphiphilic glue between two phases. A thermal recrystallization process was inserted before leaching to induce a phase separation, which subsequently squeezes out PEG to form a hydrophilic shell. Characterizations of XRD and DSC indicated the composition and mixing states of materials. The water contact angle test qualitatively presented the excellent hydrophilicity compared to the pure PLA or PLA-PEG simple blend scaffold. The scanning electron microscope results confirmed the formation of porous structure of [Formula: see text] pore size, with an observable phase separation on the surface. The scaffold was degraded in PBS at [Formula: see text], and the degradation exhibits a three-stage behavior, which evidenced the amphiphilically glued phase separations. PMID:26324121