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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

    ) of tent-butyl acrylate (tBA) in a controlled fashion by use of NiBr2(PPh3)(2) catalyst to produce Prot-PCL-b-PtBA with narrow polydispersities (1.17-1.39). Subsequent mild deprotection protocols provided HS-PCL-b-PAA. Reduction of a gold salt in the presence of this macroligand under thiol......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. Gold Nanoparticles Protected with Thiol-Derivatized Amphiphilic Poly( -caprolactone)-b-poly(acrylic acid)

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Hvilsted, Søren

    2008-01-01

    Amphiphilic poly(c-caprolactone)-b-poly(acrylic acid) (HS-PCL-b-PAA) bearing thiol functionality at the PCL terminal has been synthesized by a combination of ring-opening polymerization (ROP) of c-caprolactone (c-CL), esterification of hydroxy chain end with protected mercaptoacetic acid, subsequ....... As a result stable, aggregation-free nanopaticles with moderate dispersity as estimated from UV-visible spectroscopy and transmission electron microscopy (TEM) data were obtained....... 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...

  3. Synthesis and characterization of biodegradable poly (ethylene glycol) and poly (caprolactone diol) end capped poly (propylene fumarate) cross linked amphiphilic hydrogel as tissue engineering scaffold material.

    Science.gov (United States)

    Krishna, Lekshmi; Jayabalan, Muthu

    2009-12-01

    Biodegradable poly (caprolactone diol-co-propylene fumarate-co-ethylene glycol) amphiphilic polymer with poly (ethylene glycol) and poly (caprolactone diol) chain ends (PCL-PPF-PEG) was prepared. PCL-PPF-PEG undergoes fast setting with acrylamide (aqueous solution) by free radical polymerization and produces a crosslinked hydrogel. The cross linked and freeze-dried amphiphilic material has porous and interconnected network. It undergoes higher degree of swelling and water absorption to form hydrogel with hydrophilic and hydrophobic domains at the surface and appreciable tensile strength. The present hydrogel is compatible with L929 fibroblast cells. PCL-PPF-PEG/acrylamide hydrogel is a candidate scaffold material for tissue engineering applications.

  4. Amphiphilic poly(ether ester amide) multiblock copolymers as biodegradable matrices for the controlled release of proteins

    NARCIS (Netherlands)

    Bezemer, J.M.; Oude Weme, P.; Grijpma, Dirk W.; Dijkstra, Pieter J.; van Blitterswijk, Clemens; Feijen, Jan

    2000-01-01

    Amphiphilic poly(ether ester amide) (PEEA) multiblock copolymers were synthesized by polycondensation in the melt from hydrophilic poly(ethylene glycol) (PEG), 1,4-dihydroxybutane and short bisester-bisamide blocks. These amide blocks were prepared by reaction of 1,4-diaminobutane with dimethyl

  5. Synthesis, Amphiphilic Property and Thermal Stability of Novel Main-chain Poly(o-carborane-benzoxazines)

    Science.gov (United States)

    Yang, Xiaoxue; Han, Guo; Yang, Zhen; Zhang, Xiaoa; Jiang, Shengling; Lyu, Yafei

    2017-10-01

    Five poly(o-carborane-benzoxazines) were synthesized via Mannich reaction of o-carborane bisphenol, paraformaldehyde, and diamine, and their structures were well characterized. Light transmission and 1H NMR in D2O confirmed that poly(o-carborane-benzoxazines) with PEG segments showed excellent water solubility and amphiphilic property. TGA analyses were conducted under nitrogen and air, and the results showed that the polymers own high initial decomposition temperatures owing to the shielding effect of carborane moiety on its adjacent aromatic structures. Besides, poly(o-carborane-benzoxazines) own high char yield at elevated temperatures, for the boron atom could combine with oxygen from the polymer structure or/and the air and be oxidized to form boron oxide, and thus the polymer weight is retained to a large extent. PEG segments had an adverse effect on the initial decomposition and char yield, and thus their concentration should be adjusted to control the polymer’s thermal stability.

  6. Novel amphiphilic poly(dimethylsiloxane) based polyurethane networks tethered with carboxybetaine and their combined antibacterial and anti-adhesive property

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jingxian; Fu, Yuchen; Zhang, Qinghua, E-mail: qhzhang@zju.edu.cn; Zhan, Xiaoli; Chen, Fengqiu

    2017-08-01

    Highlights: • An amphiphilic poly(dimethylsiloxane) (PDMS) based polyurethane (PU) network tethered with carboxybetaine is prepared. • The surface distribution of PDMS and zwitterionic segments produces an obvious amphiphilic heterogeneous surface. • This designed PDMS-based amphiphilic PU network exhibits combined antibacterial and anti-adhesive properties. - Abstract: The traditional nonfouling materials are powerless against bacterial cells attachment, while the hydrophobic bactericidal surfaces always suffer from nonspecific protein adsorption and dead bacterial cells accumulation. Here, amphiphilic polyurethane (PU) networks modified with poly(dimethylsiloxane) (PDMS) and cationic carboxybetaine diol through simple crosslinking reaction were developed, which had an antibacterial efficiency of 97.7%. Thereafter, the hydrolysis of carboxybetaine ester into zwitterionic groups brought about anti-adhesive properties against bacteria and proteins. The surface chemical composition and wettability performance of the PU network surfaces were investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and contact angle analysis. The surface distribution of PDMS and zwitterionic segments produced an obvious amphiphilic heterogeneous surface, which was demonstrated by atomic force microscopy (AFM). Enzyme-linked immunosorbent assays (ELISA) were used to test the nonspecific protein adsorption behaviors. With the advantages of the transition from excellent bactericidal performance to anti-adhesion and the combination of fouling resistance and fouling release property, the designed PDMS-based amphiphilic PU network shows great application potential in biomedical devices and marine facilities.

  7. 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.

  8. In-vitro cytotoxic activities of poly(2-ethyl-2-oxazoline-based amphiphilic block copolymers prepared by CuAAC click chemistry

    Directory of Open Access Journals (Sweden)

    S. Gulyuz

    2018-02-01

    Full Text Available Synthesis and characterization of well-defined amphiphilic block copolymers containing poly(2-ethyl-2-oxazoline as hydrophilic block and poly(ε-caprolactone or poly(L-lactide as hydrophobic block is achieved by copper-catalyzed azide-alkyne cycloaddition (CuAAC click chemistry. The clickable precursors, α-alkyne-functionalized poly(ε-caprolactone and poly(L-lactide and ω-azido-functionalized poly(2-ethyl-2-oxazoline are simply prepared and joined using copper sulfate/ascorbic acid catalyst system at room temperature. The structures of precursors and amphiphilic block copolymers are characterized by spectroscopic, chromatographic and thermal analyses. The cytotoxic activities of resulting amphiphilic block copolymers and their precursors are investigated in the prostate epithelial and cancer cells under in-vitro conditions. The treatment of the healthy prostate epithelial cell line PNT1A reveals that no significant cytotoxicity, whereas some significant toxic effects on the prostate cancer cell lines are observed.

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

    International Nuclear Information System (INIS)

    Sheikh, Faheem A.; Barakat, Nasser A.M.; Kim, Byoung-Suhk; Aryal, Santosh; Khil, Myung-Seob; Kim, Hak-Yong

    2009-01-01

    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 1 H 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.

  10. Nanostructures and surface hydrophobicity of self-assembled thermosets involving epoxy resin and poly(2,2,2-trifluoroethyl acrylate)-block-poly(ethylene oxide) amphiphilic diblock copolymer.

    Science.gov (United States)

    Yi, Fangping; Zheng, Sixun; Liu, Tianxi

    2009-02-19

    Poly(2,2,2-trifluoroethyl acrylate)-block-poly(ethylene oxide) (PTFEA-b-PEO) amphiphilic diblock copolymer was synthesized via the reversible addition-fragmentation transfer polymerization of 2,2,2-triffluroethyl acrylate with dithiobenzoyl-terminated poly(ethylene oxide) as a chain-transfer agent. The amphiphilic diblock copolymer was incorporated into epoxy resin to prepare the nanostructured epoxy thermosets. The nanostructures were investigated by means of atomic force microscopy, small-angle X-ray scattering, and dynamic mechanical analysis. In terms of the miscibility of the subchains of the block copolymer with epoxy after and before curing reaction, it is judged that the formation of the nanostructures follows the mechanism of self-assembly. The static contact angle measurements indicate that the nanostructured thermosets containing PTFEA-b-PEO diblock copolymer displayed a significant enhancement in surface hydrophobicity as well as a reduction in surface free energy. The improvement in surface properties was ascribed to the enrichment of the fluorine-containing subchain (i.e., PTFEA block) of the amphiphilic diblock copolymer on the surface of the nanostructured thermosets, which was evidenced by surface atomic force microscopy and energy-dispersive X-ray spectroscopy.

  11. Poly(Acrylic Acid-b-Styrene) Amphiphilic Multiblock Copolymers as Building Blocks for the Assembly of Discrete Nanoparticles

    Science.gov (United States)

    Greene, Anna C.; Zhu, Jiahua; Pochan, Darrin J.; Jia, Xinqiao; Kiick, Kristi L.

    2011-01-01

    In order to expand the utility of current polymeric micellar systems, we have developed amphiphilic multiblock copolymers containing alternating blocks of poly(acrylic acid) and poly(styrene). Heterotelechelic poly(tert-butyl acrylate-b-styrene) diblock copolymers containing an α-alkyne and an ω-azide were synthesized by atom transfer radical polymerization (ATRP), allowing control over the molecular weight while maintaining narrow polydispersity indices. The multiblock copolymers were constructed by copper-catalyzed azide-alkyne cycloaddition of azide-alkyne end functional diblock copolymers which were then characterized by 1H NMR, FT-IR and SEC. The tert-butyl moieties of the poly(tert-butyl acrylate-b-styrene) multiblock copolymers were easily removed to form the poly(acrylic acid-b-styrene) multiblock copolymer ((PAA-PS)9), which contained up to 9 diblock repeats. The amphiphilic multiblock (PAA-PS)9 (Mn = 73.3 kg/mol) was self-assembled by dissolution into tetrahydrofuran and extensive dialysis against deionized water for 4 days. The critical micelle concentration (CMC) for (PAA-PS)9 was determined by fluorescence spectroscopy using pyrene as a fluorescent probe and was found to be very low at 2 × 10-4 mg/mL. The (PAA-PS)9 multiblock was also analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The hydrodynamic diameter of the particles was found to be 11 nm. Discrete spherical particles were observed by TEM with an average particle diameter of 14 nm. The poly(acrylic acid) periphery of the spherical particles should allow for future conjugation of biomolecules. PMID:21552373

  12. 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 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. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  13. Novel amphiphilic poly(dimethylsiloxane) based polyurethane networks tethered with carboxybetaine and their combined antibacterial and anti-adhesive property

    Science.gov (United States)

    Jiang, Jingxian; Fu, Yuchen; Zhang, Qinghua; Zhan, Xiaoli; Chen, Fengqiu

    2017-08-01

    The traditional nonfouling materials are powerless against bacterial cells attachment, while the hydrophobic bactericidal surfaces always suffer from nonspecific protein adsorption and dead bacterial cells accumulation. Here, amphiphilic polyurethane (PU) networks modified with poly(dimethylsiloxane) (PDMS) and cationic carboxybetaine diol through simple crosslinking reaction were developed, which had an antibacterial efficiency of 97.7%. Thereafter, the hydrolysis of carboxybetaine ester into zwitterionic groups brought about anti-adhesive properties against bacteria and proteins. The surface chemical composition and wettability performance of the PU network surfaces were investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and contact angle analysis. The surface distribution of PDMS and zwitterionic segments produced an obvious amphiphilic heterogeneous surface, which was demonstrated by atomic force microscopy (AFM). Enzyme-linked immunosorbent assays (ELISA) were used to test the nonspecific protein adsorption behaviors. With the advantages of the transition from excellent bactericidal performance to anti-adhesion and the combination of fouling resistance and fouling release property, the designed PDMS-based amphiphilic PU network shows great application potential in biomedical devices and marine facilities.

  14. 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.

  15. 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

  16. Synthesis of amphiphilic poly(ε-caprolactone)-b-poly( N-vinylcaprolactam) block copolymers via the combination of RAFT polymerization and click chemistry

    International Nuclear Information System (INIS)

    Assis, Paulo Henrique; Aguiar, Graziele Aparecida de Jesus; Moraes, Rodolfo Minto de; Medeiros, Simone de Fatima; Santos, Amilton Martins

    2016-01-01

    Full text: In recent years, well-defined block copolymers composed of a hydrophilic and hydrophobic segments have gained much interest as drug carriers, because of their enhanced solubility and sustained release of the drug in controlled delivery systems [1]. The development of strategies to obtain block copolymers has attracted considerable attention, due to the possibility to combine characteristic properties of the homopolymers. A wide variety of well-defined block copolymers have been successfully synthesized by combining the efficiency and selectivity of click chemistry with the powerful RAFT polymerization mechanism. In the present work, well-defined amphiphilic, biocompatible, partially biodegradable, and thermosensitive poly(ε-caprolactone)-b-poly(N-vinylcaprolactam) (PCL-b-PNVCL) block copolymers were synthesized by combining ring opening polymerization (ROP), reversible addition-fragmentation chain transfer (RAFT) polymerization and subsequent click chemistry reaction. Alkyne-terminated poly(ε-caprolactone) (alkyne-PCL) was obtained by the ring opening polymerization of ε-caprolactone (ε-CL) using propargyl alcohol as initiator and stannous-2-ethylhexanoate [Sn(Oct) 2 ] as catalyst. The azide end-capped-poly(N-vinylcaprolactam) (PNVCL-N 3 ) was synthesized by reversible addition-fragmentation chain transfer/macromolecular design via interchange of xanthates (RAFT/MADIX) polymerization of the N-vinylcaprolactam (NVCL) mediated by a novel chain transfer agent comprising an azide function , 2-azidoethyl[(ethoxycarbonothioyl)thio](phenyl)acetate. These functionalized homopolymers, alkyne-PCL and PNVCL-N 3 , were coupled by the 1,3 dipolar cycloaddition reaction in order to obtain the corresponding block copolymers. These (co)polymers were characterized by FTIR, 1 H NMR and GPC measurements. Reference: 1. RAMESH, K., SINGH, S., MITRA, K., CHATTOPADHYAY, D., MISRA, N., & RAY, B. (2015). Colloid and Polymer Science, 1-9. (author)

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

    KAUST Repository

    Luxenhofer, Robert; Sahay, Gaurav; Schulz, Anita; Alakhova, Daria; Bronich, Tatiana K.; Jordan, Rainer; Kabanov, Alexander V.

    2011-01-01

    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

  18. Microporous gel electrolytes based on amphiphilic poly(vinylidene fluoride-co-hexafluoropropylene) for lithium batteries

    International Nuclear Information System (INIS)

    Yu Shicheng; Chen Lie; Chen Yiwang; Tong Yongfen

    2012-01-01

    Poly(vinylidene fluoride-co-hexafluoropropylene) grafted poly(poly(ethylene glycol) methyl ether methacrylate) (PVDF-HFP-g-PPEGMA) is simply prepared by single-step synthesis directly via atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA) from poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Thermal, mechanical, swelling and electrochemical properties, as well as microstructures of the prepared polymer electrolytes, are evaluated and the effects of the various contents and average molecular weights of PEGMA on those properties are also been investigated. By phase inversion technique, the copolymer membranes tend to form well-defined microporous morphology with the increase of content and average molecular weight of PEGMA, due to the competition and cooperation between the hydrophilic PEGMA segments and hydrophobic PVDF-HFP. When these membranes are gelled with 1 M LiCF 3 SO 3 in ethylene carbonate (EC)/propylene carbonate (PC) (1:1, v/v), their saturated electrolyte uptakes (up to 323.5%) and ion conductivities (up to 2.01 × 10 -3 S cm -1 ) are dramatically improved with respect to the pristine PVDF-HFP, ascribing to the strong affinity of the hydrophilic PEGMA segments with the electrolytes. All the polymer electrolytes are electrochemically stable up to 4.7 V versus Li/Li + , and show good mechanical properties. Coin cells based on the polymer electrolytes show stable charge-discharge cycles and deliver discharge capacities to LiFePO 4 is up to 156 mAh g -1 .

  19. Development of controlled release formulations of azadirachtin-A employing poly(ethylene glycol) based amphiphilic copolymers.

    Science.gov (United States)

    Kumar, Jitendra; Shakil, Najam A; Singh, Manish K; Singh, Mukesh K; Pandey, Alka; Pandey, Ravi P

    2010-05-01

    Controlled release (CR) formulations of azadirachtin-A, a bioactive constituent derived from the seed of Azadirachta indica A. Juss (Meliaceae), have been prepared using commercially available polyvinyl chloride, polyethylene glycol (PEG) and laboratory synthesized poly ethylene glycol-based amphiphilic copolymers. Copolymers of polyethylene glycol and various dimethyl esters, which self assemble into nano micellar aggregates in aqueous media, have been synthesized. The kinetics of azadirachtin-A, release in water from the different formulations was studied. Release from the commercial polyethylene glycol (PEG) formulation was faster than the other CR formulations. The rate of release of encapsulated azadirachtin-A from nano micellar aggregates is reduced by increasing the molecular weight of PEG. The diffusion exponent (n value) of azadirachtin-A, in water ranged from 0.47 to 1.18 in the tested formulations. The release was diffusion controlled with a half release time (t(1/2)) of 3.05 to 42.80 days in water from different matrices. The results suggest that depending upon the polymer matrix used, the application rate of azadirachtin-A can be optimized to achieve insect control at the desired level and period.

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

    Science.gov (United States)

    Duan, Xiaopin; Xiao, Jisheng; Yin, Qi; Zhang, Zhiwen; Mao, Shirui; Li, Yaping

    2012-01-01

    Background 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. PMID:23028224

  1. Phase behavior of poly(dimethylsiloxane)-poly(ethylene oxide) amphiphilic block and graft copolymers in compressed carbon dioxide

    International Nuclear Information System (INIS)

    Stoychev, Ivan; Peters, Felix; Kleiner, Matthias; Sadowski, Gabriele; Clerc, Sebastien; Ganachaud, Francois; Chirat, Mathieu; Lacroix-Desmazes, Patrick; Fournel, Bruno

    2012-01-01

    The phase behavior of triblock and graft-type poly(dimethylsiloxane) (PDMS)-poly(ethylene oxide) (PEO) copolymer surfactants has been investigated in compressed carbon dioxide (CO 2 ). For this purpose, cloud-point pressures have been measured in the pressure and temperature range from P=10 to 40 MPa and from T= 293 to 338 K. The Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state (EoS) has been applied to model the experimental data in order to better understand the influence of the structure of the copolymers on the phase behavior of the system. The pure-component parameters for PDMS have been fitted originally to PDMS/n-pentane system. These parameters are successfully applied for PDMS in CO 2 by adjusting a temperature-dependent binary interaction parameter. The phase behavior of the triblock copolymers was successfully predicted by PC-SAFT. In contrast, the phase behavior of the graft copolymers was difficult to predict accurately at this stage. (authors)

  2. 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

  3. A directional entrapment modification on the polyethylene surface by the amphiphilic modifier of stearyl-alcohol poly(ethylene oxide) ether

    Science.gov (United States)

    Lu, Qiang; Chen, Yi; Huang, Juexin; Huang, Jian; Wang, Xiaolin; Yao, Jiaying

    2018-05-01

    A novel entrapment modification method involving directional implantation of the amphiphilic modifier of stearyl-alcohol poly(ethylene oxide) ether (AEO) into the high-density polyethylene (HDPE) surface is proposed. This modification technique allows the AEO modifier to be able to spontaneously attain and subsequently penetrate into the swollen HDPE surface with its hydrophobic stearyl segment, while its hydrophilic poly(ethylene oxide) (PEO) segment spontaneously points to water. The AEO modifier with a HLB number below 8.7 was proved appropriate for the directional entrapment, Nevertheless, AEOs with larger HLB numbers were also effective modifiers in the presence of salt additives. In addition, a larger and hydrophobic micelle, induced respectively by the AEO concentration above 1.3 × 10-2 mol/L and the entrapping temperature above the cloud point of AEO, could lead to a sharp contact angle decline of the modified surface. Finally, a hydrophilic HDPE surface with the modifier coverage of 38.9% was reached by the directional entrapment method, which is far larger than that of 19.2% by the traditional entrapment method.

  4. Investigation of the role of hydrophilic chain length in amphiphilic perfluoropolyether/poly(ethylene glycol) networks: towards high-performance antifouling coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yapei; Pitet, Louis M.; Finlay, John A.; Brewer, Lenora H.; Cone, Gemma; Betts, Douglas E.; Callow, Maureen E.; Callow, James A.; Wendt, Dean E.; Hillmyer, Marc A.; DeSimone, Joseph M. (Birmingham UK); (NCSU); (UNC); (Cal. Polytech.); (UMM)

    2013-03-07

    The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M{sub w} = 1500 g mol{sup -1}) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M{sub w} = 300, 475, 1100 g mol{sup -1}), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased advancing and receding contact angles with increasing PEG chain length. In particular, the PFPE/PEG1100 network had a much lower advancing contact angle than static contact angle, suggesting that the PEG1100 segments diffuse to the polymer/water interface quickly. The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of Ulva, adhesion being lower than to a polydimethyl elastomer, Silastic T2.

  5. Investigation of the role of hydrophilic chain length in amphiphilic perfluoropolyether/poly(ethylene glycol) networks: towards high-performance antifouling coatings.

    Science.gov (United States)

    Wang, Yapei; Pitet, Louis M; Finlay, John A; Brewer, Lenora H; Cone, Gemma; Betts, Douglas E; Callow, Maureen E; Callow, James A; Wendt, Dean E; Hillmyer, Marc A; DeSimonea, Joseph M

    2011-01-01

    The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M(w) = 1500 g mol(-1)) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M(w) = 300, 475, 1100 g mol(-1)), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased advancing and receding contact angles with increasing PEG chain length. In particular, the PFPE/PEG1100 network had a much lower advancing contact angle than static contact angle, suggesting that the PEG1100 segments diffuse to the polymer/water interface quickly. The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of Ulva, adhesion being lower than to a polydimethyl elastomer, Silastic T2.

  6. 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.

  7. A Long-Acting BMP-2 Release System Based on Poly(3-hydroxybutyrate) Nanoparticles Modified by Amphiphilic Phospholipid for Osteogenic Differentiation

    Science.gov (United States)

    Peng, Xiaochun; Chen, Yunsu; Li, Yamin; Wang, Yiming

    2016-01-01

    We explored a novel poly(3-hydroxybutyrate) (PHB) nanoparticle loaded with hydrophilic recombinant human BMP-2 with amphiphilic phospholipid (BPC-PHB NP) for a rapid-acting and long-acting delivery system of BMP-2 for osteogenic differentiation. The BPC-PHB NPs were prepared by a solvent evaporation method and showed a spherical particle with a mean particle size of 253.4 nm, mean zeta potential of −22.42 mV, and high entrapment efficiency of 77.18%, respectively. For BPC-PHB NPs, a short initial burst release of BMP-2 from NPs in 24 h was found and it has steadily risen to reach about 80% in 20 days for in vitro test. BPC-PHB NPs significantly reduced the burst release of BMP-2, as compared to that of PHB NPs loading BMP-2 without PL (B-PHB NPs). BPC-PHB NPs maintained the content of BMP-2 for a long-term osteogenic differentiation. The OCT-1 cells with BPC-PHB NPs have high ALP activity in comparison with others. The gene markers for osteogenic differentiation were significantly upregulated for sample with BPC-PHB NPs, implying that BPC-PHB NPs can be used as a rapid-acting and long-acting BMP-2 delivery system for osteogenic differentiation. PMID:27379249

  8. Second Generation Amphiphilic Poly-Lysine Dendrons Inhibit Glioblastoma Cell Proliferation without Toxicity for Neurons or Astrocytes.

    Directory of Open Access Journals (Sweden)

    Jolanta Janiszewska

    Full Text Available Glioblastomas are the most common malignant primary brain tumours in adults and one of the most aggressive and difficult-to-treat cancers. No effective treatment exits actually for this tumour and new therapeutic approaches are needed for this disease. One possible innovative approach involves the nanoparticle-mediated specific delivery of drugs and/or genetic material to glioblastoma cells where they can provide therapeutic benefits. In the present work, we have synthesised and characterised several second generation amphiphilic polylysine dendrons to be used as siRNA carriers. We have found that, in addition to their siRNA binding properties, these new compounds inhibit the proliferation of two glioblastoma cell lines while being nontoxic for non-tumoural central nervous system cells like neurons and glia, cell types that share the anatomical space with glioblastoma cells during the course of the disease. The selective toxicity of these nanoparticles to glioblastoma cells, as compared to neurons and glial cells, involves mitochondrial depolarisation and reactive oxygen species production. This selective toxicity, together with the ability to complex and release siRNA, suggests that these new polylysine dendrons might offer a scaffold in the development of future nanoparticles designed to restrict the proliferation of glioblastoma cells.

  9. Poly(N-isopropyl acrylamide)-block-poly(n-butyl acrylate) thermoresponsive amphiphilic copolymers: synthesis, characterization and self-assembly behavior in aqueous solutions

    Czech Academy of Sciences Publication Activity Database

    Škvarla, J.; Zedník, J.; Šlouf, Miroslav; Pispas, S.; Štěpánek, M.

    2014-01-01

    Roč. 61, December (2014), s. 124-132 ISSN 0014-3057 R&D Projects: GA TA ČR TE01020118 Institutional support: RVO:61389013 Keywords : thermoresponsive block copolymers * poly(N-isopropyl acrylamide) * light scattering Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.005, year: 2014

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

    KAUST Repository

    Cho, Youngjin; Cho, Daehwan; Park, Jay Hoon; Frey, Margaret W.; Ober, Christopher K.; Joo, Yong Lak

    2012-01-01

    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

  11. 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.

  12. 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

  13. Amphiphilic block copolymers for biomedical applications

    Science.gov (United States)

    Zupancich, John Andrew

    Amphiphilic block copolymer self-assembly provides a versatile means to prepare nanoscale objects in solution. Control over aggregate shape is granted through manipulation of amphiphile composition and the synthesis of well-defined polymers offers the potential to produce micelles with geometries optimized for specific applications. Currently, polymer micelles are being investigated as vehicles for the delivery of therapeutics and attempts to increase efficacy has motivated efforts to incorporate bioactive ligands and stimuli-responsive character into these structures. This thesis reports the synthesis and self-assembly of biocompatible, degradable polymeric amphiphiles. Spherical, cylindrical, and bilayered vesicle structures were generated spontaneously by the direct dispersion of poly(ethylene oxide)-b-poly(gamma-methyl-ε-caprolactone) block copolymers in water and solutions were characterized with cryogenic transmission electron microscopy (cryo-TEM). The dependence of micelle structure on diblock copolymer composition was examined through the systematic variation of the hydrophobic block molecular weight. A continuous evolution of morphology was observed with coexistence of aggregate structures occurring in windows of composition intermediate to that of pure spheres, cylinders and vesicles. A number of heterobifunctional poly(ethylene oxide) polymers were synthesized for the preparation of ligand-functionalized amphiphilic diblock copolymers. The effect of ligand conjugation on block copolymer self-assembly and micelle morphology was also examined. An RGD-containing peptide sequence was efficiently conjugated to a set of well characterized poly(ethylene oxide)-b-poly(butadiene) copolymers. The reported aggregate morphologies of peptide-functionalized polymeric amphiphiles deviated from canonical structures and the micelle clustering, cylinder fragmentation, network formation, and multilayer vesicle generation documented with cryo-TEM was attributed to

  14. Self-assembly of poly(ionic liquid) (PIL)-based amphiphilic homopolymers into vesicles and supramolecular structures with dyes and silver nanoparticles

    KAUST Repository

    Manojkumar, Kasina

    2017-04-27

    The incorporation of both hydrophilic and hydrophobic segments in homopolymers leads to their self-assembly into nanostructures in selective solvents, owing to their amphiphilic character. Here we report the RAFT polymerization of N-imidazole-3-propylmethacrylamide and the further quaternization of the resulting polymer with different alkyl bromides of a varying chain length, which afforded well-defined polymeric ionic liquids (PILs) 1-4. These PILs are characterized by the presence of both hydrophobic alkyl chains and hydrophilic ionic moieties, allowing their spontaneous self-assembly in water, forming distinct polymeric vesicles (= polymersomes) the size of which can be varied as a function of alkyl chain length. As demonstrated by the dye-encapsulation study, a particular organic-soluble PIL, 3, consisting of a dodecyl side-chain enabled the transfer of the water-soluble Rose Bengal dye, from an aqueous solution to the organic phase. In addition, polymersomes obtained from a PIL (2) featuring butyl side chains were used as templates and polymeric stabilizers of silver nanoparticles (NPs), i.e. leading to AgNP@PIL hybrids, as observed by transmission electron microscopy (TEM). It was found that the extent of functionalization of polymersomes by the Ag-based NPs varied greatly before and after the end-group removal of the PIL. Altogether, this report emphasizes the facile synthesis of amphiphilic homoPILs and their manipulation in water for dye encapsulation and for stabilization of silver NPs.

  15. Self-assembly of poly(ionic liquid) (PIL)-based amphiphilic homopolymers into vesicles and supramolecular structures with dyes and silver nanoparticles

    KAUST Repository

    Manojkumar, Kasina; Mecerreyes, David; Taton, Daniel; Gnanou, Yves; Vijayakrishna, Kari

    2017-01-01

    The incorporation of both hydrophilic and hydrophobic segments in homopolymers leads to their self-assembly into nanostructures in selective solvents, owing to their amphiphilic character. Here we report the RAFT polymerization of N-imidazole-3-propylmethacrylamide and the further quaternization of the resulting polymer with different alkyl bromides of a varying chain length, which afforded well-defined polymeric ionic liquids (PILs) 1-4. These PILs are characterized by the presence of both hydrophobic alkyl chains and hydrophilic ionic moieties, allowing their spontaneous self-assembly in water, forming distinct polymeric vesicles (= polymersomes) the size of which can be varied as a function of alkyl chain length. As demonstrated by the dye-encapsulation study, a particular organic-soluble PIL, 3, consisting of a dodecyl side-chain enabled the transfer of the water-soluble Rose Bengal dye, from an aqueous solution to the organic phase. In addition, polymersomes obtained from a PIL (2) featuring butyl side chains were used as templates and polymeric stabilizers of silver nanoparticles (NPs), i.e. leading to AgNP@PIL hybrids, as observed by transmission electron microscopy (TEM). It was found that the extent of functionalization of polymersomes by the Ag-based NPs varied greatly before and after the end-group removal of the PIL. Altogether, this report emphasizes the facile synthesis of amphiphilic homoPILs and their manipulation in water for dye encapsulation and for stabilization of silver NPs.

  16. Microspheres for protein delivery prepared from amphiphilic multiblock copolymers. 1. influence of preparation techniques on particle characteristics and protein delivery

    NARCIS (Netherlands)

    Bezemer, J.M.; Radersma, R.; Grijpma, Dirk W.; Dijkstra, Pieter J.; van Blitterswijk, Clemens; Feijen, Jan

    2000-01-01

    The entrapment of lysozyme in amphiphilic multiblock copolymer microspheres by emulsification and subsequent solvent removal processes was studied. The copolymers are composed of hydrophilic poly(ethylene glycol) (PEG) blocks and hydrophobic poly(butylene terephthalate) (PBT) blocks. Direct solvent

  17. 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

    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...... of the corresponding monomers followed by deblocking reaction leads to well-defined amphiphiles with narrow molecular weight distributions (PDI ≤ 1.29) and varying content of methacrylic acid. The graft copolymers showed effective surface adsorption and lubrication for self-mated poly(dimethylsiloxane) (PDMS) contacts...

  18. Lipase polystyrene giant amphiphiles.

    Science.gov (United States)

    Velonia, Kelly; Rowan, Alan E; Nolte, Roeland J M

    2002-04-24

    A new type of giant amphiphilic molecule has been synthesized by covalently connecting a lipase enzyme headgroup to a maleimide-functionalized polystyrene tail (40 repeat units). The resulting biohybrid forms catalytic micellar rods in water.

  19. Co-Immobilization of Superoxide Dismutase with Catalase on Soft Microparticles Formed by Self-Assembly of Amphiphilic Poly(Aspartic Acid

    Directory of Open Access Journals (Sweden)

    Siyu Mao

    2017-07-01

    Full Text Available Through genetic engineering technology, catalase (CAT and superoxide dismutase (SOD have been separately fused to an elastin-like polypeptide (ELP. Thus, the enzymes can be purified through phase transition. Hexadecylamine-modified poly(aspartic acid (HPASP is able to self-assemble, forming soft microparticles. The HPASP microparticles were used to co-immobilize SOD-ELP and CAT-ELP through amidation reaction. Circular dichroism (CD confirmed that the secondary structures of the co-immobilized enzymes have been preserved. Fluorescence spectra showed that the co-immobilized enzymes exhibited a higher stability than the free enzymes. Dismutation of superoxide by superoxide dismutase (SOD generates hydrogen peroxide. By using the co-immobilized enzymes (SOD-ELP/CAT-ELP@HPASP, the generated hydrogen peroxide of SOD-ELP can be decomposed in situ by CAT-ELP. Activity assay results demonstrated that the superoxide anion (•O2− scavenging ability is 63.15 ± 0.75% for SOD-ELP/CAT-ELP@HPASP. The advantages of the approach of enzyme co-immobilization include the fact that the soft support HPASP itself is a polypeptide in nature, the stability of immobilized enzymes is improved, and a high activity has been achieved. Potentially SOD-ELP/CAT-ELP@HPASP can be applied in the cosmetic industry.

  20. 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

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

    KAUST Repository

    Song, Xiaowan; Cao, Ming; Chen, Peng; Xia, Ru; Zheng, Zhengzhi; Miao, Jibin; Yang, Bin; Su, Lifen; Qian, Jiasheng; Feng, Xiaoshuang

    2016-01-01

    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

  2. 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.

  3. Amphiphilic brushes from metallo-supramolecular block copolymers

    NARCIS (Netherlands)

    Guillet, P.; Fustin, C.A.; Wouters, D.; Höppener, S.; Schubert, U.S.; Gohy, J.M.W.

    2009-01-01

    A novel strategy to control the formation of amphiphilic brushes from metallo-supramol. block copolymers is described. The investigated copolymer consists of a polystyrene block linked to a poly(ethylene oxide) one via a charged bis-terpyridine ruthenium(ii) complex (PS-[Ru]-PEO). The initial

  4. Amphiphilic building blocks for self-assembly: from amphiphiles to supra-amphiphiles.

    Science.gov (United States)

    Wang, Chao; Wang, Zhiqiang; Zhang, Xi

    2012-04-17

    The process of self-assembly spontaneously creates well-defined structures from various chemical building blocks. Self-assembly can include different levels of complexity: it can be as simple as the dimerization of two small building blocks driven by hydrogen bonding or as complicated as a cell membrane, a remarkable supramolecular architecture created by a bilayer of phospholipids embedded with functional proteins. The study of self-assembly in simple systems provides a fundamental understanding of the driving forces and cooperativity behind these processes. Once the rules are understood, these guidelines can facilitate the research of highly complex self-assembly processes. Among the various components for self-assembly, an amphiphilic molecule, which contains both hydrophilic and hydrophobic parts, forms one of the most powerful building blocks. When amphiphiles are dispersed in water, the hydrophilic component of the amphiphile preferentially interacts with the aqueous phase while the hydrophobic portion tends to reside in the air or in the nonpolar solvent. Therefore, the amphiphiles aggregate to form different molecular assemblies based on the repelling and coordinating forces between the hydrophilic and hydrophobic parts of the component molecules and the surrounding medium. In contrast to conventional amphiphiles, supra-amphiphiles are constructed on the basis of noncovalent interactions or dynamic covalent bonds. In supra-amphiphiles, the functional groups can be attached to the amphiphiles by noncovalent synthesis, greatly speeding their construction. The building blocks for supra-amphiphiles can be either small organic molecules or polymers. Advances in the development of supra-amphiphiles will not only enrich the family of conventional amphiphiles that are based on covalent bonds but will also provide a new kind of building block for the preparation of complex self-assemblies. When polymers are used to construct supra-amphiphiles, the resulting

  5. Stimuli Responsive Amphiphilic Assemblies

    Science.gov (United States)

    2013-11-18

    Enzyme- Sensitive, Amphiphilic- Dendrimer -Based Nanoparticles through Photochemical Crosslinking, Chemistry - A European Journal, (10 2011): 0. doi...17, 2012 (Organizers: R. P. Singh) 8th International Dendrimer Symposium (IDS-8), Madrid, Spain, June 23-27, 2013 (Organizers: Dr. M’Angeles...investigate the pH-induced changes in surface properties. Nanocarriers that can be effectively transported across cellular membranes have potential in a

  6. Amphiphilic block co-polymers: preparation and application in nanodrug and gene delivery.

    Science.gov (United States)

    Xiong, Xiao-Bing; Binkhathlan, Ziyad; Molavi, Ommoleila; Lavasanifar, Afsaneh

    2012-07-01

    Self-assembly of amphiphilic block co-polymers composed of poly(ethylene oxide) (PEO) as the hydrophilic block and poly(ether)s, poly(amino acid)s, poly(ester)s and polypropyleneoxide (PPO) as the hydrophobic block can lead to the formation of nanoscopic structures of different morphologies. These structures have been the subject of extensive research in the past decade as artificial mimics of lipoproteins and viral vectors for drug and gene delivery. The aim of this review is to provide an overview of the synthesis of commonly used amphiphilic block co-polymers. It will also briefly go over some pharmaceutical applications of amphiphilic block co-polymers as "nanodelivery systems" for small molecules and gene therapeutics. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  7. Amphiphilic cyclodextrin nanoparticles.

    Science.gov (United States)

    Varan, Gamze; Varan, Cem; Erdoğar, Nazlı; Hıncal, A Atilla; Bilensoy, Erem

    2017-10-15

    Cyclodextrins are cyclic oligosaccharides obtained by enzymatic digestion of starch. The α-, β- and γ- cyclodextrins contain respectively 6, 7 and 8 glucopyranose units, with primary and secondary hydroxyl groups located on the narrow and wider rims of a truncated cone shape structure. Such structure is that of a hydrophobic inner cavity with a hydrophilic outer surface allowing to interact with a wide range of molecules like ions, protein and oligonucleotides to form inclusion complexes. Many cyclodextrin applications in the pharmaceutical area have been widely described in the literature due to their low toxicity and low immunogenicity. The most important is to increase the solubility of hydrophobic drugs in water. Chemically modified cyclodextrin derivatives have been synthesized to enhance their properties and more specifically their pharmacological activity. Among these, amphiphilic derivatives were designed to build organized molecular structures, through selfassembling systems or by incorporation in lipid membranes, expected to improve the vectorization in the organism of the drug-containing cyclodextrin cavities. These derivatives can form a variety of supramolecular structures such as micelles, vesicles and nanoparticles. The purpose of this review is to summarize applications of amphiphilic cyclodextrins in different areas of drug delivery, particularly in protein and peptide drug delivery and gene delivery. The article highlights important amphiphilic cyclodextrin applications in the design of novel delivery systems like nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. 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...

  9. Amphiphilic block copolymers for drug delivery.

    Science.gov (United States)

    Adams, Monica L; Lavasanifar, Afsaneh; Kwon, Glen S

    2003-07-01

    Amphiphilic block copolymers (ABCs) have been used extensively in pharmaceutical applications ranging from sustained-release technologies to gene delivery. The utility of ABCs for delivery of therapeutic agents results from their unique chemical composition, which is characterized by a hydrophilic block that is chemically tethered to a hydrophobic block. In aqueous solution, polymeric micelles are formed via the association of ABCs into nanoscopic core/shell structures at or above the critical micelle concentration. Upon micellization, the hydrophobic core regions serve as reservoirs for hydrophobic drugs, which may be loaded by chemical, physical, or electrostatic means, depending on the specific functionalities of the core-forming block and the solubilizate. Although the Pluronics, composed of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide), are the most widely studied ABC system, copolymers containing poly(L-amino acid) and poly(ester) hydrophobic blocks have also shown great promise in delivery applications. Because each ABC has unique advantages with respect to drug delivery, it may be possible to choose appropriate block copolymers for specific purposes, such as prolonging circulation time, introduction of targeting moieties, and modification of the drug-release profile. ABCs have been used for numerous pharmaceutical applications including drug solubilization/stabilization, alteration of the pharmacokinetic profile of encapsulated substances, and suppression of multidrug resistance. The purpose of this minireview is to provide a concise, yet detailed, introduction to the use of ABCs and polymeric micelles as delivery agents as well as to highlight current and past work in this area. Copyright 2003 Wiley-Liss, Inc. and the American Pharmacists Association

  10. 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.......20 (SLL/C and SBCC/C) and ∼0.28 (C/L). Finally, the specific influences of the strongly amphiphilic nature of the AmphComb blocks on the observed morphological and hierarchical behaviours of our system are discussed. For reference, stoichiometric strongly amphiphilic comb-like (AmphComb) ionic...

  11. Unconventional, amphiphilic polymers based on chiral polyethylene oxide derivatives I. Synthesis and Characterization.

    NARCIS (Netherlands)

    Janssen, H.M.; Peeters, E.; Zundert, van M.F.; Genderen, van M.H.P.; Meijer, E.W.

    1997-01-01

    The first representatives of a new class of synthetic, amphiphilic polymers based on poly(ethylene oxide) are introduced. These polymers are constituted in a similar way to that for coiled-coil-forming peptides: the polymers possess a regular repeat of apolar (A) residues in a polar (P) sequence of

  12. 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...

  13. Nanoparticles based on novel amphiphilic polyaspartamide copolymers

    International Nuclear Information System (INIS)

    Craparo, Emanuela Fabiola; Teresi, Girolamo; Ognibene, Maria Chiara; Casaletto, Maria Pia; Bondi, Maria Luisa; Cavallaro, Gennara

    2010-01-01

    In this article, the synthesis of two amphiphilic polyaspartamide copolymers, useful to obtain polymeric nanoparticles without using surfactants or stabilizing agents, is described. These copolymers were obtained starting from α,β-poly-(N-2-hydroxyethyl)-dl-aspartamide (PHEA) by following a novel synthetic strategy. In particular, PHEA and its pegylated derivative (PHEA-PEG 2000 ) were functionalized with poly(lactic acid) (PLA) through 1,1'-carbonyldiimidazole (CDI) activation to obtain PHEA-PLA and PHEA-PEG 2000 -PLA graft copolymers, respectively. These copolymers were properly purified and characterized by 1 H-NMR, FT-IR, and Size Exclusion Chromatography (SEC) analyses, which confirmed that derivatization reactions occurred. Nanoparticles were obtained from PHEA-PLA and PHEA-PEG 2000 -PLA graft copolymers by using the high pressure homogenization-solvent evaporation method, avoiding the use of surfactants or stabilizing agents. Polymeric nanoparticles were characterized by dimensional analysis, before and after freeze-drying process, and Scanning Electron Microscopy (SEM). Zeta potential measurements and X-ray Photoelectron Spectroscopy (XPS) analysis demonstrated the presence of PEG and/or PHEA onto the PHEA-PEG 2000 -PLA and PHEA-PLA nanoparticle surface, respectively.

  14. Poly(ethylene oxide)–Poly(propylene oxide)-Based Copolymers for ...

    African Journals Online (AJOL)

    Amphiphilic poly(ethylene oxide)–poly(propylene oxide) (PEO–PPO)-based copolymers are thermoresponsive materials having aggregation properties in aqueous medium. As hydrosolubilizers of poorly water-soluble drugs and improved stability of sensitive agents, these materials have been investigated for improvement ...

  15. Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Szymusiak, Magdalena; Kalkowski, Joseph; Luo, Hanying; Donovan, Alexander J.; Zhang, Pin; Liu, Chang; Shang, Weifeng; Irving, Thomas; Herrera-Alonso, Margarita; Liu, Ying (JHU); (IIT); (UIC)

    2017-08-31

    A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. The structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.

  16. Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Szymusiak, Magdalena [Department; Kalkowski, Joseph [Department; Luo, Hanying [Department; Donovan, Alexander J. [Department; Zhang, Pin [Department; Liu, Chang [Department; Shang, Weifeng [Department; Irving, Thomas [Department; Herrera-Alonso, Margarita [Department; Liu, Ying [Department; Department

    2017-08-16

    A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. The structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.

  17. Ionization of amphiphilic acidic block copolymers.

    Science.gov (United States)

    Colombani, Olivier; Lejeune, Elise; Charbonneau, Céline; Chassenieux, Christophe; Nicolai, Taco

    2012-06-28

    The ionization behavior of an amphiphilic diblock copolymer poly(n-butyl acrylate(50%)-stat-acrylic acid(50%))(100)-block-poly(acrylic acid)(100) (P(nBA(50%)-stat-AA(50%))(100)-b-PAA(100), DH50) and of its equivalent triblock copolymer P(nBA(50%)-stat-AA(50%))(100)-b-PAA(200)-b-P(nBA(50%)-stat-AA(50%))(100) (TH50) were studied by potentiometric titration either in pure water or in 0.5 M NaCl. These polymers consist of a hydrophilic acidic block (PAA) connected to a hydrophobic block, P(nBA(50%)-stat-AA(50%))(100), whose hydrophobic character has been mitigated by copolymerization with hydrophilic units. We show that all AA units, even those in the hydrophobic block could be ionized. However, the AA units within the hydrophobic block were less acidic than those in the hydrophilic block, resulting in the preferential ionization of the latter block. The preferential ionization of PAA over that of P(nBA(50%)-stat-AA(50%))(100) was stronger at higher ionic strength. Remarkably, the covalent bonds between the PAA and P(nBA(50%)-stat-AA(50%))(100) blocks in the diblock or the triblock did not affect the ionization of each block, although the self-association of the block copolymers into spherical aggregates modified the environment of the PAA blocks compared to when PAA was molecularly dispersed.

  18. 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

    2014-11-04

    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.

  19. Improved surface property of PVDF membrane with amphiphilic zwitterionic copolymer as membrane additive

    International Nuclear Information System (INIS)

    Li Jianhua; Li Mizi; Miao Jing; Wang Jiabin; Shao Xisheng; Zhang Qiqing

    2012-01-01

    An attempt to improve hydrophilicity and anti-fouling properties of PVDF membranes, a novel amphiphilic zwitterionic copolymer poly(vinylidene fluoride)-graft-poly(sulfobetaine methacrylate) (PVDF-g-PSBMA) was firstly synthesized by atom transfer radical polymerization (ATRP) and used as amphiphilic copolymer additive in the preparation of PVDF membranes. The PVDF-g-PSBMA/PVDF blend membranes were prepared by immersion precipitation process. Fourier transform infrared attenuated reflection spectroscopy (FTIR-ATR) and X-ray photoelectronic spectroscopy (XPS) measurements confirmed that PSBMA brushes from amphiphilic additives were preferentially segregated to membrane-coagulant interface during membrane formation. The morphology of membranes was characterized by scanning electron microscopy (SEM). Water contact angle measurements showed that the surface hydrophilicity of PVDF membranes was improved significantly with the increasing of amphiphilic copolymer PVDF-g-PSBMA in cast solution. Protein static adsorption experiment and dynamic fouling resistance experiment revealed that the surface enrichment of PSBMA brush endowed PVDF blend membrane great improvement of surface anti-fouling ability.

  20. Improved surface property of PVDF membrane with amphiphilic zwitterionic copolymer as membrane additive

    Energy Technology Data Exchange (ETDEWEB)

    Li Jianhua, E-mail: jhli_2005@163.com [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China); Li Mizi; Miao Jing; Wang Jiabin; Shao Xisheng [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China); Zhang Qiqing, E-mail: zhangqiq@126.com [Institute of Biomedical and Pharmaceutical Technology and College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350001 (China) and Institute of Biomedical Engineering, Chinese Academy of Medical Science, Peking Union Medical College, Tianjin 300192 (China)

    2012-06-15

    An attempt to improve hydrophilicity and anti-fouling properties of PVDF membranes, a novel amphiphilic zwitterionic copolymer poly(vinylidene fluoride)-graft-poly(sulfobetaine methacrylate) (PVDF-g-PSBMA) was firstly synthesized by atom transfer radical polymerization (ATRP) and used as amphiphilic copolymer additive in the preparation of PVDF membranes. The PVDF-g-PSBMA/PVDF blend membranes were prepared by immersion precipitation process. Fourier transform infrared attenuated reflection spectroscopy (FTIR-ATR) and X-ray photoelectronic spectroscopy (XPS) measurements confirmed that PSBMA brushes from amphiphilic additives were preferentially segregated to membrane-coagulant interface during membrane formation. The morphology of membranes was characterized by scanning electron microscopy (SEM). Water contact angle measurements showed that the surface hydrophilicity of PVDF membranes was improved significantly with the increasing of amphiphilic copolymer PVDF-g-PSBMA in cast solution. Protein static adsorption experiment and dynamic fouling resistance experiment revealed that the surface enrichment of PSBMA brush endowed PVDF blend membrane great improvement of surface anti-fouling ability.

  1. Amphiphilic copolymers based on PEG-acrylate as surface active water viscosifiers : Towards new potential systems for enhanced oil recovery

    NARCIS (Netherlands)

    Raffa, Patrizio; Broekhuis, Antonius A.; Picchioni, Francesco

    2016-01-01

    With the purpose of investigating new potential candidates for enhanced oil recovery (EOR), amphiphilic copolymers based on Poly(ethylene glycol) methyl ether acrylate (PEGA) have been prepared by Atom Transfer Radical Polymerization (ATRP). A P(PEGA) homopolymer, a block copolymer with styrene

  2. 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....

  3. Tetrazole amphiphile inducing growth of conducting polymers hierarchical nanostructures and their electromagnetic absorption properties

    Science.gov (United States)

    Xie, Aming; Sun, Mengxiao; Zhang, Kun; Xia, Yilu; Wu, Fan

    2018-05-01

    Conducting polymers (CPs) at nano scales endow materials with special optical, electrical, and magnetic properties. The crucial factor to construct and regulate the micro-structures of CPs is the inducing reagent, particular in its chemical structure, such active sites, self-assembling properties. In this paper, we design and synthesize an amphiphile bearing tetrazole moiety on its skeleton, and use this amphiphile as an inducing reagent to prepare and regulate the micro-structures of a series of CPs including polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) and poly(p-phenylenediamine). Because of the unique electric properties of CPs and size effect, we next explored the electromagnetic absorption performances of these CPs nanostructures. A synergetic combination of electric loss and magnetic loss is used to explain the absorption mechanism of these CPs nano-structures.

  4. 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.

  5. Shape Recovery with Concomitant Mechanical Strengthening of Amphiphilic Shape Memory Polymers in Warm Water

    International Nuclear Information System (INIS)

    Zhang, Ben; DeBartolo, Janae E.; Song, Jie

    2017-01-01

    Maintaining adequate or enhancing mechanical properties of shape memory polymers (SMPs) after shape recovery in an aqueous environment are greatly desired for biomedical applications of SMPs as self-fitting tissue scaffolds or minimally invasive surgical implants. Here we report stable temporary shape fixing and facile shape recovery of biodegradable triblock amphiphilic SMPs containing a poly(ethylene glycol) (PEG) center block and flanking poly(lactic acid) or poly(lactic-co-glycolic acid) blocks in warm water, accompanied with concomitant enhanced mechanical strengths. Differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WXRD) and small-angle X-ray scattering (SAXS) analyses revealed that the unique stiffening of the amphiphilic SMPs upon hydration was due to hydration-driven microphase separation and PEG crystallization. We further demonstrated that the chemical composition of degradable blocks in these SMPs could be tailored to affect the persistence of hydration-induced stiffening upon subsequent dehydration. These properties combined open new horizons for these amphiphilic SMPs for smart weight-bearing in vivo applications (e.g. as self-fitting intervertebral discs). In conclusion, this study also provides a new material design strategy to strengthen polymers in aqueous environment in general.

  6. A new class of amphiphiles: annelids; Une nouvelle classe d'amphiphiles: les annelides

    Energy Technology Data Exchange (ETDEWEB)

    Markovitsi, Dimitra

    1983-12-14

    This research thesis presents annelids, organometallic compounds which may form into organised phases. The author describes the synthesis of an amphipathic ligand of its cobaltic and cupric complexes. The formation of micelles and of thermotropic and lyotropic liquid crystals is highlighted. The copper (II) annelid environment is studied by electronic paramagnetic resonance spectroscopy. The author demonstrates, in micellar phase, the effect of molecular cooperativity on acid-base balance, on metallic ion complexation, on the photo-sensitized electronic transfer, and on the formation of poly-nuclear complexes [French] Les annelides, composes organometalliques susceptibles de former des phases organisees, sont presentes. La synthese d'un ligand amphipathique et de ses complexes cobaltique et cuivrique est decrite. La formation de micelles et de cristaux liquides, thermotropes et lyotropes, a l'aide de ces amphiphiles, est mise en evidence. L'environnement de l'annelide de cuivre (II) est etudie par spectroscopie de resonance paramagnetique electronique. L'effet de la cooperativite moleculaire sur l'equilibre acidobasique, sur la complexation des ions metalliques, sur le transfert electronique photosensibilise et sur la formation des complexes polynucleaires est demontre en phase micellaire. (auteur)

  7. Synthesis and properties of amphiphilic hyperbranched polyethers as pigment dispersant

    Science.gov (United States)

    Xu, Q.; Zhou, Y. J.; Long, S. J.; Liu, Y. G.; Li, J. H.

    2018-01-01

    Hyperbranched polymers possess prominent properties such as low viscosity, good solubility, high rheological property, environmental non-toxic, and so on, which have potential applications in coatings. In this study, the amphiphilic hyperbranched polyethers (AHPs) consisting of hydrophobic hyperbranched polyethers core and hydrophilic poly (ethylene glycol) arms with different degree of branching (DB) under various reaction temperatures was prepared by the cation ring-opening polymerization. Their structures were characterized by IR, 13CNMR and GPC. Their dispersion properties for pigment particles were investigated. The AHP47 with 0.47 DB was found to have good dispersion properties for Yellow HGR. This work would provide experimental data and theoretical foundation for the application of hyperbranched polyethers in environmental protection coating.

  8. Amphiphilic Copolymers Shuttle Drugs Across the Blood-Brain Barrier.

    Science.gov (United States)

    Clemens-Hemmelmann, Mirjam; Kuffner, Christiane; Metz, Verena; Kircher, Linda; Schmitt, Ulrich; Hiemke, Christoph; Postina, Rolf; Zentel, Rudolf

    2016-05-01

    Medical treatment of diseases of the central nervous system requires transport of drugs across the blood-brain barrier (BBB). Here, it is extended previously in vitro experiments with a model compound to show that the non-water-soluble and brain-impermeable drug domperidone (DOM) itself can be enriched in the brain by use of an amphiphilic copolymer as a carrier. This carrier consists of poly(N-(2-hydroxypropyl)-methacrylamide), statistically copolymerized with 10 mol% hydrophobic lauryl methacrylate, into whose micellar aggregates DOM is noncovalently absorbed. As tested in a BBB model efficient transport of DOM across, the BBB is achievable over a wide range of formulations, containing 0.8 to 35.5 wt% domperidone per copolymer. In neither case, the polymer itself is translocated across the BBB model. In vivo experiments in mice show that already 10 min after intraperitoneal injection of the polymer/domperidone (PolyDOM) formulation, domperidone can be detected in blood and in the brain. Highest serum and brain levels of domperidone are detected 40 min after injection. At that time point serum domperidone is increased 48-fold. Most importantly, domperidone is exclusively detectable in high amounts in the brain of PolyDOM injected mice and not in mice injected with bare domperidone. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Recombinant Amphiphilic Protein Micelles for Drug Delivery

    OpenAIRE

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

    2011-01-01

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

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

  11. Controlled Synthesis of AB2 amphiphilic triarm star-shaped block copolymers by ring-opening polymerization

    OpenAIRE

    Petrova, Svetla; Riva, Raphaël; Jérôme, Christine; Lecomte, Philippe; Mateva, Rosa

    2009-01-01

    This paper describes the synthesis of a novel amphiphilic AB2 triarm star-shaped copolymer with A = non-toxic and biocompatible hydrophilic poly(ethylene oxide) (PEO) and B = biodegradable and hydrophobic poly(ε-caprolactone) (PCL). A series of AB2 triarm star-shaped copolymers with different molecular weights for the PCL block were successfully synthesized by a three-step procedure. α-methoxy-ω-epoxy-poly(ethylene oxide) (PEO-epoxide) was first synthesized by the nucleophilic substitution of...

  12. Nanoparticles Embedded in Amphiphilic Membranes for Carbon Dioxide Separation and Dehumidification.

    Science.gov (United States)

    Yong, Wai Fen; Ho, Yan Xun; Chung, Tai-Shung

    2017-10-23

    Polymers containing ethylene oxide (EO) groups have gained significant interest as the EO groups have favorable interactions with polar molecules such as H 2 O, quadrupolar molecules such as CO 2 , and metal ions. However, the main challenges of poly(ethylene oxide) (PEO) membranes are their weak mechanical properties and high crystallinity nature. The amphiphilic copolymer made from PEO terephthalate and poly(butylene terephthalate) (PEOT/PBT) comprises both hydrophilic and hydrophobic segments. The hydrophilic PEOT segment is thermosensitive, which facilities gas transports whereas the hydrophobic PBT segment is rigid, which provides mechanical robustness. This work demonstrates a new strategy to design amphiphilic mixed matrix membranes (MMMs) by incorporating zeolitic imidazolate framework, ZIF-71, into the PEOT/PBT copolymer. The resultant membrane shows an enhanced CO 2 permeability with an ideal CO 2 /N 2 selectivity surpassing the original PEOT/PBT and Robeson's Upper bound line. The nanoparticles-embedded amphiphilic membranes exhibit characteristics of high transparency and mechanical robustness. Mechanically strong composite hollow fiber membranes consisting of PEOT/PBT/ZIF-71 as the selective layer were also prepared. The resultant hollow fibers possess an excellent CO 2 permeance of 131 GPU (gas permeation units), CO 2 /N 2 selectivity of 52.6, H 2 O permeance of 9300 GPU and H 2 O/N 2 selectivity of 3700, showing great potential for industrial CO 2 capture and dehumidification. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Triblock Copolymers with Grafted Fluorine-Free Amphiphilic Non-Ionic Side Chains for Antifouling and Fouling-Release Applications

    Energy Technology Data Exchange (ETDEWEB)

    Y Cho; H Sundaram; C Weinman; M Paik; M Dimitriou; J Finlay; M Callow; J Callow; E Kramer; C Ober

    2011-12-31

    Fluorine-free, amphiphilic, nonionic surface active block copolymers (SABCs) were synthesized through chemical modification of a polystyrene-block-poly(ethylene-ran-butylene)-block-polyisoprene triblock copolymer precursor with selected amphiphilic nonionic Brij and other surfactants. Amphiphilicity was imparted by a hydrophobic aliphatic group combined with a hydrophilic poly(ethylene glycol) (PEG) group-containing moiety. The surfaces were characterized by dynamic water contact angle, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure (NEXAFS) analysis. In biofouling assays, settlement (attachment) of both spores of the green alga Ulva and cells of the diatom Navicula on SABCs modified with Brij nonionic side chains was significantly reduced relative to a PDMS standard, with a nonionic surfactant combining a PEG group and an aliphatic moiety demonstrating the best performance. Additionally, a fouling-release assay using sporelings (young plants) of Ulva and Navicula suggested that the SABC derived from nonionic Brij side chains also out-performed PDMS as a fouling-release material. Good antifouling and fouling-release properties were not demonstrated for the other two amphiphilic surfaces derived from silicone and aromatic group containing nonionic surfactants included in this study. The results suggest that small differences in chemical surface functionality impart more significant changes with respect to the antifouling settlement and fouling-release performance of materials than overall wettability behavior.

  14. 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.

  15. An Amylase-Responsive Bolaform Supra-Amphiphile.

    Science.gov (United States)

    Kang, Yuetong; Cai, Zhengguo; Tang, Xiaoyan; Liu, Kai; Wang, Guangtong; Zhang, Xi

    2016-02-01

    An amylase-responsive bolaform supra-amphiphile was constructed by the complexation between β-cyclodextrin and a bolaform covalent amphiphile on the basis of host-guest interaction. The bolaform covalent amphiphile could self-assemble in solution, forming sheet-like aggregates and displaying weak fluorescence because of aggregation-induced quenching. The addition of β-cyclodextrin led to the formation of the bolaform supra-amphiphile, prohibiting the aggregation of the bolaform covalent amphiphile and accompanying with the significant recovery of fluorescence. Upon the addition of α-amylase, with the degradation β-cyclodextrin, the fluorescence of the supra-amphiphile would quench gradually and significantly, and the quenching rate linearly correlated to the concentration of α-amylase. This study enriches the field of supra-amphiphiles on the basis of noncovalent interactions, and moreover, it may provide a facile way to estimate the activity of α-amylase.

  16. 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...... dynamics simulation of this self-assembly behaviour....

  17. Diagram of state of stiff amphiphilic macromolecules

    NARCIS (Netherlands)

    Markov, Vladimir A.; Vasilevskaya, Valentina V.; Khalatur, Pavel G.; ten Brinke, Gerrit; Khokhlov, Alexei R.

    2007-01-01

    We studied coil-globule transitions in stiff-chain amphiphilic macromolecules via computer modeling and constructed phase diagrams for such molecules in terms of solvent quality and persistence length. We showed that the shape of the phase diagram essentially depends on the macromolecule degree of

  18. Amphiphilic copolymers for fouling-release coatings

    DEFF Research Database (Denmark)

    Noguer, Albert Camós; Olsen, Stefan Møller; Hvilsted, Søren

    of the coatings [9,10,11]. This work shows the effect of an amphiphilic copolymer that induces hydrophilicity on the surface of the silicone-based fouling release coatings. The behaviour of these copolymers within the coating upon immersion and the interaction of these surface-active additives with other...

  19. Fluctuations and structure of amphiphilic films

    International Nuclear Information System (INIS)

    Gourier, CH.

    1996-01-01

    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.)

  20. 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)

    Yang, Xiaoxia; Ji, Xiaoqing; Shi, Chunhuan; Liu, Jing; Wang, Haiyang; Luan, Yuxia

    2014-01-01

    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 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. 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.

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    Joachim Kohn

    2012-10-01

    Full Text Available 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. We therefore selected it 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.

  4. 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.)

  5. HPMA-based block copolymers promote differential drug delivery kinetics for hydrophobic and amphiphilic molecules.

    Science.gov (United States)

    Tomcin, Stephanie; Kelsch, Annette; Staff, Roland H; Landfester, Katharina; Zentel, Rudolf; Mailänder, Volker

    2016-04-15

    We describe a method how polymeric nanoparticles stabilized with (2-hydroxypropyl)methacrylamide (HPMA)-based block copolymers are used as drug delivery systems for a fast release of hydrophobic and a controlled release of an amphiphilic molecule. The versatile method of the miniemulsion solvent-evaporation technique was used to prepare polystyrene (PS) as well as poly-d/l-lactide (PDLLA) nanoparticles. Covalently bound or physically adsorbed fluorescent dyes labeled the particles' core and their block copolymer corona. Confocal laser scanning microscopy (CLSM) in combination with flow cytometry measurements were applied to demonstrate the burst release of a fluorescent hydrophobic drug model without the necessity of nanoparticle uptake. In addition, CLSM studies and quantitative calculations using the image processing program Volocity® show the intracellular detachment of the amphiphilic block copolymer from the particles' core after uptake. Our findings offer the possibility to combine the advantages of a fast release for hydrophobic and a controlled release for an amphiphilic molecule therefore pointing to the possibility to a 'multi-step and multi-site' targeting by one nanocarrier. We describe thoroughly how different components of a nanocarrier end up in cells. This enables different cargos of a nanocarrier having a consecutive release and delivery of distinct components. Most interestingly we demonstrate individual kinetics of distinct components of such a system: first the release of a fluorescent hydrophobic drug model at contact with the cell membrane without the necessity of nanoparticle uptake. Secondly, the intracellular detachment of the amphiphilic block copolymer from the particles' core after uptake occurs. This offers the possibility to combine the advantages of a fast release for a hydrophobic substance at the time of interaction of the nanoparticle with the cell surface and a controlled release for an amphiphilic molecule later on therefore

  6. 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 ...

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

    Science.gov (United States)

    Chae, Pil Seok; Rana, Rohini R; Gotfryd, Kamil; Rasmussen, Søren G F; Kruse, Andrew C; Cho, Kyung Ho; Capaldi, Stefano; Carlsson, Emil; Kobilka, Brian; Loland, Claus J; Gether, Ulrik; Banerjee, Surajit; Byrne, Bernadette; Lee, John K; Gellman, Samuel H

    2013-03-21

    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 al. (Science, 2012, 337, 473).

  8. Multilayers of Fluorinated Amphiphilic Polyions for Marine Fouling Prevention

    NARCIS (Netherlands)

    Zhu, X.; Guo, S.; Janczewski, D.; Parra-Velandia, F.J.; Teo, S.L-M.; Vancso, Gyula J.

    2014-01-01

    Sequential layer-by-layer (LbL) deposition of polyelectrolytes followed by chemical cross-linking was investigated as a method to fabricate functional amphiphilic surfaces for marine biofouling prevention applications. A novel polyanion, grafted with amphiphilic perfluoroalkyl polyethylene glycol

  9. Freezing-induced self-assembly of amphiphilic molecules

    Science.gov (United States)

    Albouy, P. A.; Deville, S.; Fulkar, A.; Hakouk, K.; Impéror-Clerc, M.; Klotz, M.; Liu, Q.; Marcellini, M.; Perez, J.

    The self-assembly of amphiphilic molecules usually takes place in a liquid phase, near room temperature. Here, using small angle X-ray scattering (SAXS) experiments performed in real time, we show that freezing of aqueous solutions of copolymer amphiphilic molecules can induce self-assembly below 0{\\deg}C.

  10. 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.

  11. 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...... effective adsorption only when PMEA was employed as the anchoring block. For PAA-b-PS, the poor adsorption properties are chiefly attributed to micellization due to the high interfacial tension between the PS core and water. The poor lubricating properties of PAA-b-PS diblock copolymer for a PDMS...

  12. Fragrance compounds and amphiphilic association structures.

    Science.gov (United States)

    Friberg, S E

    1998-05-01

    Fragrance formulations have traditionally been based on alcohol as the solvent, but the recent legal restrictions on volatile organic solvents have prompted the industry to change to aqueous solubilized systems. The article reviews the fundamental factors in the application of such systems evaluating the influence by different amphiphilic association structures on the vapor pressure of fragrance compounds. This information is subsequently used to estimate the variation of fragrance compound vapor pressures during evaporation. The results reveal that the vapor pressure versus time variation is improved compared to solvent-based formulations.

  13. Self-Assembly of Charged Amphiphilic Diblock Copolymers with Insoluble Blocks of Decreasing Hydrophobicity: From Kinetically Frozen Colloids to Macrosurfactants

    Energy Technology Data Exchange (ETDEWEB)

    M Jacquin; P Muller; H Cottet; O Theodoly

    2011-12-31

    We have investigated the self-assembly properties in aqueous solution of amphiphilic diblock copolymers with insoluble blocks of different hydrophobicity and demonstrated that the condition to obtain dynamic micelles is to design samples with insoluble blocks of low enough hydrophobicity. We focus here on results with new water-soluble amphiphilic diblock copolymers poly(diethyleneglycol ethylether acrylate)-b-poly(acrylic acid), or PDEGA-b-PAA. The physical characteristics of PDEGA-b-PAA micelles at high ionization have been determined by small angle neutron scattering (SANS). We show that PDEGA-b-PAA samples form micelles at thermodynamic equilibrium. The critical micelle concentrations (CMCs) decrease strongly with ionic strength and temperature due to a solvent quality decrease for, respectively, the corona and the core. This behavior of reversible aggregation is remarkable as compared to the behavior of kinetically frozen aggregation that has been widely observed with samples of similar architecture and different hydrophobic blocks, for example, poly(styrene)-b-poly(acrylic acid), PS-b-PAA, and poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA. We have measured the interfacial tension between water and the homopolymers PDEGA and PBA at, respectively, 3 and 20 mN/m at room temperature, which permits one to estimate the energy cost to extract a unimer from a micelle. The results are consistent with a micelle association that is fast for PDEGA-b-PAA and kinetically frozen PBA-b-PAA. Hence, PDEGA-b-PAA samples form a new system of synthetic charged macrosurfactant with unique properties of fast dynamic association, tunable charge, and water solubility even at temperatures and NaCl concentrations as high as 65 C and 1 M.

  14. Biomimetic surface coatings from modular amphiphilic proteins

    Science.gov (United States)

    Harden, James; Wan, Fan; Fischer, Stephen; Dick, Scott

    2010-03-01

    Recombinant DNA methods have been used to develop a library of diblock protein polymers for creating designer biofunctional interfaces. These proteins are composed of a surface-active, amphiphilic block joined to a disordered, water soluble block with an end terminal bioactive domain. The amphiphilic block has a strong affinity for many synthetic polymer surfaces, providing a facile means of imparting biological functionality to otherwise bio-neutral materials through physical self-assembly. We have incorporated a series of bioactive end domains into this diblock motif, including sequences that encode specific cell binding and signaling functions of extracellular matrix constituents (e.g. RGD and YIGSR). In this talk, we show that these diblock constructs self-assemble into biofunctional surface coatings on several model synthetic polymer materials. We demonstrate that surface adsorption of the proteins has minimal impacts on the presentation of the bioactive domains in the soluble block, and through the use of microscopic and cell proliferation assays, we show that the resulting biofunctional interfaces are capable of inducing appropriate cellular responses in a variety of human cell types.

  15. 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...... and the nanoparticles. With their diverse particle shapes and internal structures as well as their different thermal behavior, aggregate states and polarities, the systems offer promising possibilities as delivery systems for lipophilic, amphiphilic and water soluble drugs.......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...

  16. 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.

  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. Compartmentalization Technologies via Self-Assembly and Cross-Linking of Amphiphilic Random Block Copolymers in Water.

    Science.gov (United States)

    Matsumoto, Mayuko; Terashima, Takaya; Matsumoto, Kazuma; Takenaka, Mikihito; Sawamoto, Mitsuo

    2017-05-31

    Orthogonal self-assembly and intramolecular cross-linking of amphiphilic random block copolymers in water afforded an approach to tailor-make well-defined compartments and domains in single polymer chains and nanoaggregates. For a double compartment single-chain polymer, an amphiphilic random block copolymer bearing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic dodecyl, benzyl, and olefin pendants was synthesized by living radical polymerization (LRP) and postfunctionalization; the dodecyl and benzyl units were incorporated into the different block segments, whereas PEG pendants were statistically attached along a chain. The copolymer self-folded via the orthogonal self-assembly of hydrophobic dodecyl and benzyl pendants in water, followed by intramolecular cross-linking, to form a single-chain polymer carrying double yet distinct hydrophobic nanocompartments. A single-chain cross-linked polymer with a chlorine terminal served as a globular macroinitiator for LRP to provide an amphiphilic tadpole macromolecule comprising a hydrophilic nanoparticle and a hydrophobic polymer tail; the tadpole thus self-assembled into multicompartment aggregates in water.

  19. From superamphiphobic to amphiphilic polymeric surfaces with ordered hierarchical roughness fabricated with colloidal lithography and plasma nanotexturing.

    Science.gov (United States)

    Ellinas, K; Tserepi, A; Gogolides, E

    2011-04-05

    Ordered, hierarchical (triple-scale), superhydrophobic, oleophobic, superoleophobic, and amphiphilic surfaces on poly(methyl methacrylate) PMMA polymer substrates are fabricated using polystyrene (PS) microparticle colloidal lithography, followed by oxygen plasma etching-nanotexturing (for amphiphilic surfaces) and optional subsequent fluorocarbon plasma deposition (for amphiphobic surfaces). The PS colloidal microparticles were assembled by spin-coating. After etching/nanotexturing, the PMMA plates are amphiphilic and exhibit hierarchical (triple-scale) roughness with microscale ordered columns, and dual-scale (hundred nano/ten nano meter) nanoscale texture on the particles (top of the column) and on the etched PMMA surface. The spacing, diameter, height, and reentrant profile of the microcolumns are controlled with the etching process. Following the design requirements for superamphiphobic surfaces, we demonstrate enhancement of both hydrophobicity and oleophobicity as a result of hierarchical (triple-scale) and re-entrant topography. After fluorocarbon film deposition, we demonstrate superhydrophobic surfaces (contact angle for water 168°, compared to 110° for a flat surface), as well as superoleophobic surfaces (153° for diiodomethane, compared to 80° for a flat surface).

  20. 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...... 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...

  1. Facially amphiphilic thiol capped gold and silver nanoparticles

    Indian Academy of Sciences (India)

    Abstract. 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.

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

    Science.gov (United States)

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

    2010-06-01

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

  3. 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.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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. - 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. 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.

  6. Amphiphilic Imbalance and Stabilization of Block Copolymer Micelles on-Demand through Combinational Photo-Cleavage and Photo-Crosslinking.

    Science.gov (United States)

    Zhang, Xuan; Wang, Youpeng; Li, Guo; Liu, Zhaotie; Liu, Zhongwen; Jiang, Jinqiang

    2017-01-01

    An amphiphilic block copolymer of poly(ethylene oxide)-b-poly((N-methacryloxy phthalimide)-co-(7-(4-vinyl-benzyloxyl)-4-methylcoumarin)) (PEO 45 -b-P(MAPI 36 -co-VBC 4 )) is designed to improve the micellar stability during the photo-triggered release of hydrophobic cargoes. Analysis of absorption and emission spectra, solution transmittance, dynamic light scattering, and transmission electron microscopy supports that polymer micelles of PEO 45 -b-P(MAPI 36 -co-VBC 4 ) upon the combinational irradiation of 365 and 254 nm light can be solubilized through the photolysis of phthalimide esters and simultaneously crosslinked via the partially reversible photo-dimerization of coumarins. The photo-triggered release experiment shows that the leakage of doxorubicin molecules from crosslinked micelles can be predictably regulated by controlling the irradiation time of 365 and 254 nm light. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Versatile antifouling polyethersulfone filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive.

    Science.gov (United States)

    Zhao, Yi-Fan; Zhang, Pei-Bin; Sun, Jian; Liu, Cui-Jing; Yi, Zhuan; Zhu, Li-Ping; Xu, You-Yi

    2015-06-15

    Here we describe the development of versatile antifouling polyethersulfone (PES) filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive. Amphiphilic polyethersulfone-block-poly(2-hydroxyethyl methacrylate) (PES-b-PHEMA) was beforehand designed and used as the blending additive of PES membranes prepared by phase inversion technique. The surface enriched PHEMA blocks on membrane surface acted as an anchor to immobilize the initiating site. Poly(sulfobetaine methacrylate) (PSBMA) were subsequently grafted onto the PES blend membranes by surface-initiated atom transfer radical polymerization (SI-ATRP). The analysis of surface chemistry confirmed the successful grafting of zwitterionic PSBMA brushes on PES membrane surface. The resulted PES-g-PSBMA membranes were capable of separating proteins from protein solution and oil from oil/water emulsion efficiently. Furthermore, the modified membranes showed high hydrophilicity and strongly antifouling properties due to the incorporation of well-defined PSBMA layer. In addition, the PES-g-PSBMA membranes exhibited excellent blood compatibility and durability during the washing process. The developed antifouling PES membranes are versatile and can find their applications in protein filtration, blood purification and oil/water separation, etc. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. 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.

  9. 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. (Petar); Yoncheva, K. (Krassimira); Mokreva, P. (Pavlina); Konstantinov, S. (Spiro); Irache, J.M. (Juan Manuel); 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 ...

  10. Catanionic mixtures forming gemini-like amphiphiles.

    Science.gov (United States)

    Sakai, Hideki; Okabe, Yuji; Tsuchiya, Koji; Sakai, Kenichi; Abe, Masahiko

    2011-01-01

    The properties of aqueous mixtures of cationic species with alkyl dicarboxylic acid compounds have been studied. The cationic compounds used in this study were tertiary amine-type N-methyl-N-(2,3-dioxypropyl)hexadecylamine (C16amine) and quaternary ammonium-type N,N-dimethyl-N-(2,3-dioxypropyl)hexadecylammonium chloride (C16Q). The alkyl dicarboxylic acid compounds used were HOOC(CH(2))(10)COOH (C12H) and its sodium salt (C12Na). Three aqueous mixtures were examined in this study: (System I) C16amine + C12H, (System II) C16Q + C12Na, and (System III) C16Q + C12H. The solution pH was set at 12 for System III. The combination of (1)H-NMR and mass spectroscopy data has suggested that a stoichiometric complex is formed in the aqueous solutions at a mole fraction of C12H (or C12Na) = 0.33. Here, the C12H (or C12Na) molecule added to the system bridges two cationic molecules, like a spacer of gemini surfactants. In fact, the static surface tensiometry has demonstrated that the stoichiometric complex behaves as gemini-like amphiphiles in aqueous solutions. Our current study offers a possible way for easily preparing gemini surfactant systems.

  11. Amphiphilic chitosan derivatives as carrier agents for rotenone

    Science.gov (United States)

    Kamari, Azlan; Aljafree, Nurul Farhana Ahmad

    2017-08-01

    In the present study, the feasibility of amphiphilic chitosan derivatives, namely oleoyl carboxymethyl chitosan (OCMCs), N,N-dimethylhexadecyl carboxymethyl chitosan (DCMCs) and deoxycholic acid carboxymethyl chitosan (DACMCs) as carrier agents for rotenone in water-insoluble pesticide formulations was investigated. Fourier Transform Infrared (FTIR) Spectrometer, CHN-O Elemental Analyser (CHN-O) and Transmission Electron Microscope (TEM) were used to characterise amphiphilic chitosan derivatives. The critical micelle concentration (CMC) of amphiphilic chitosan derivatives was determined using a Fluorescence Spectrometer. A High Performance Liquid Chromatography (HPLC) was used to determine the ability of OCMCs, DCMCs and DACMCs to load and release rotenone in an in vitro system. Based on TEM analysis, results have shown that amphiphilic chitosan derivatives formed self-assembly and exhibited spherical shape. The CMC values determined for OCMCs, DCMCs and DACMCs were 0.093, 0.098 and 0.468 mg/mL, respectively. The encapsulation efficiency (EE) values for the materials were more than 97.0%, meanwhile the loading capacity (LC) values were greater than 0.90%. OCMCs, DCMCs and DACMCs micelles exhibited an excellent ability to control the release of rotenone, of which 90.0% of rotenone was released within 40 to 52 h. In conclusion, OCMCs, DCMCs and DACMCs possess several key features to act as effective carrier agents for rotenone. Overall, amphiphilic chitosan derivatives produced in this study were successfully increased the solubility of rotenone by 49.0 times higher than free rotenone.

  12. Dissolving Microneedle Arrays for Transdermal Delivery of Amphiphilic Vaccines.

    Science.gov (United States)

    An, Myunggi; Liu, Haipeng

    2017-07-01

    Amphiphilic vaccine based on lipid-polymer conjugates is a new type of vaccine capable of self-delivering to the immune system. When injected subcutaneously, amphiphilic vaccines efficiently target antigen presenting cells in the lymph nodes (LNs) via a unique albumin-mediated transport and uptake mechanism and induce potent humoral and cellular immune responses. However, whether this new type of vaccine can be administrated via a safe, convenient microneedle-based transdermal approach remains unstudied. For such skin barrier-disruption systems, a simple application of microneedle arrays (MNs) is desired to disrupt the stratum corneum, and for rapid and pain-free self-administration of vaccines into the skin, the anatomic place permeates with an intricate mesh of lymphatic vessels draining to LNs. Here the microneedle transdermal approach is combined with amphiphilic vaccines to create a simple delivery approach which efficiently traffic molecular vaccines into lymphatics and draining LNs. The rapid release of amphiphilic vaccines into epidermis upon application of dissolving MNs to the skin of mice generates potent cellular and humoral responses, comparable or superior to those elicited by traditional needle-based immunizations. The results suggest that the amphiphilic vaccines delivered by dissolving MNs can provide a simple and safer vaccination method with enhanced vaccine efficacy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 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...... that the new amphiphile, "glyco-diosgenin" (GDN; see figure), confers enhanced stability to a variety of membrane proteins in solution relative to popular conventional detergents, such as dodecylmaltoside (DDM)....

  14. Rheological and phase behaviour of amphiphilic lipids

    Directory of Open Access Journals (Sweden)

    Alfaro, M. C.

    2000-04-01

    Full Text Available This chapter reviews the different association structures which are likely to be formed by amphiphilic lipids in the liquid-crystalline state and their corresponding shear flow properties. The structure and rheological behaviour of thermotropic liquid crystals, emphasizing the properties of smectic mesophases, and those of lyotropic liquid crystals such as: nematic, lamellar, diluted lamellar, lamellar dispersions, hexagonal and cubic mesophases are described. The importance of a comprehensive rheological characterisation, including rheo-optical techniques, is pointed out for their practical applications, development of formulations and as a useful technique to assist in the determination of phase diagrams. A historical approach has been used to discuss the evolving field of the rheology and structure identification of liquid crystals formed by amphiphilic lipids and surfactants. Non-Newtonian viscous shear flow, thixotropic and antithixotropic phenomena, linear viscoelastic properties -described by dynamic and creep compliance experiments- and non-linear viscoelastic properties - described by the difference of normal stresses and stress relaxation tests are interpreted on the basis of a microstructure-rheology relationship. The polycrystalline nature of liquid crystals turns out to be rather sensitive to shear due to the change of both size and orientation of the liquid-crystalline monodomains under flow.En este capítulo se realiza una revisión de las distintas estructuras coloidales de asociación que pueden formar los lípidos anfifílicos en estado líquido-cristalino y de sus correspondientes propiedades de flujo en cizalla. Se describe la estructura y comportamiento reológico de cristales líquidos termotrópicos, con énfasis en los de tipo esméctico, fases gel, y cristales líquidos liotrópicos: nemáticos, laminares, laminares diluidos, dispersiones de laminares, hexagonales y cúbicos. Se hace hincapié en la importancia de una

  15. Micellar Structures of Hydrophilic/Lipophilic and Hydrophilic/Fluorophilic Poly(2-oxazoline) Diblock Copolymers in Water

    DEFF Research Database (Denmark)

    Ivanova, Ruzha; Komenda, Thomas; Bonné, Tune B.

    2008-01-01

    Amphiphilic poly(2-alkyl-2-oxazoline) diblock copolymers of 2-methyl-2-oxazoline (MOx) building the hydrophilic block and either 2-nonyl-2-oxazoline (NOx) for the hydrophobic or 2-(1H,1H',2H,2H'-perfluorohexyl)-2-oxazoline (FOx) for the fluorophilic block were synthesized by sequential living...

  16. Rapid Prototyping Amphiphilic Polymer/Hydroxyapatite Composite Scaffolds with Hydration-Induced Self-Fixation Behavior

    Science.gov (United States)

    Kutikov, Artem B.; Gurijala, Anvesh

    2015-01-01

    Two major factors hampering the broad use of rapid prototyped biomaterials for tissue engineering applications are the requirement for custom-designed or expensive research-grade three-dimensional (3D) printers and the limited selection of suitable thermoplastic biomaterials exhibiting physical characteristics desired for facile surgical handling and biological properties encouraging tissue integration. Properly designed thermoplastic biodegradable amphiphilic polymers can exhibit hydration-dependent hydrophilicity changes and stiffening behavior, which may be exploited to facilitate the surgical delivery/self-fixation of the scaffold within a physiological tissue environment. Compared to conventional hydrophobic polyesters, they also present significant advantages in blending with hydrophilic osteoconductive minerals with improved interfacial adhesion for bone tissue engineering applications. Here, we demonstrated the excellent blending of biodegradable, amphiphilic poly(D,L-lactic acid)-poly(ethylene glycol)-poly(D,L-lactic acid) (PLA-PEG-PLA) (PELA) triblock co-polymer with hydroxyapatite (HA) and the fabrication of high-quality rapid prototyped 3D macroporous composite scaffolds using an unmodified consumer-grade 3D printer. The rapid prototyped HA-PELA composite scaffolds and the PELA control (without HA) swelled (66% and 44% volume increases, respectively) and stiffened (1.38-fold and 4-fold increases in compressive modulus, respectively) in water. To test the hypothesis that the hydration-induced physical changes can translate into self-fixation properties of the scaffolds within a confined defect, a straightforward in vitro pull-out test was designed to quantify the peak force required to dislodge these scaffolds from a simulated cylindrical defect at dry versus wet states. Consistent with our hypothesis, the peak fixation force measured for the PELA and HA-PELA scaffolds increased 6-fold and 15-fold upon hydration, respectively. Furthermore, we showed that

  17. 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." © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. 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

    2013-01-01

    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. PMID:23881402

  19. 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.

  20. Formation of nanophases in epoxy thermosets containing amphiphilic block copolymers with linear and star-like topologies.

    Science.gov (United States)

    Wang, Lei; Zhang, Chongyin; Cong, Houluo; Li, Lei; Zheng, Sixun; Li, Xiuhong; Wang, Jie

    2013-07-11

    In this work, we investigated the effect of topological structures of block copolymers on the formation of the nanophase in epoxy thermosets containing amphiphilic block copolymers. Two block copolymers composed of poly(ε-caprolactone) (PCL) and poly(2,2,2-trifluoroethyl acrylate) (PTFEA) blocks were synthesized to possess linear and star-shaped topologies. The star-shaped block copolymer composed a polyhedral oligomeric silsesquioxane (POSS) core and eight poly(ε-caprolactone)-block-poly(2,2,2-trifluoroethyl acrylate) (PCL-b-PTFEA) diblock copolymer arms. Both block copolymers were synthesized via the combination of ring-opening polymerization and reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process; they were controlled to have identical compositions of copolymerization and lengths of blocks. Upon incorporating both block copolymers into epoxy thermosets, the spherical PTFEA nanophases were formed in all the cases. However, the sizes of PTFEA nanophases from the star-like block copolymer were significantly lower than those from the linear diblock copolymer. The difference in the nanostructures gave rise to the different glass transition behavior of the nanostructured thermosets. The dependence of PTFEA nanophases on the topologies of block copolymers is interpreted in terms of the conformation of the miscible subchain (viz. PCL) at the surface of PTFEA microdomains and the restriction of POSS cages on the demixing of the thermoset-philic block (viz. PCL).

  1. Microspheres for protein delivery prepared from amphiphilic multiblock copolymers. 1. Influence of preparation techniques on particle characteristics and protein delivery.

    Science.gov (United States)

    Bezemer, J M; Radersma, R; Grijpma, D W; Dijkstra, P J; van Blitterswijk, C A; Feijen, J

    2000-07-03

    The entrapment of lysozyme in amphiphilic multiblock copolymer microspheres by emulsification and subsequent solvent removal processes was studied. The copolymers are composed of hydrophilic poly(ethylene glycol) (PEG) blocks and hydrophobic poly(butylene terephthalate) (PBT) blocks. Direct solvent extraction from a water-in-oil (w/o) emulsion in ethanol or methanol did not result in the formation of microspheres, due to massive polymer precipitation caused by rapid solvent extraction in these non-solvents. In a second process, microspheres were first prepared by a water-in-oil-in-water (w/o/w) emulsion system with 4% poly(vinyl alcohol) (PVA) as stabilizer in the external phase, followed by extraction of the remaining solvent. As non-solvents ethanol, methanol and mixtures of methanol and water were employed. However, the use of alcohols in the extraction medium resulted in microspheres which gave an incomplete lysozyme release at a non-constant rate. Complete lysozyme release was obtained from microspheres prepared by an emulsification-solvent evaporation method in PBS containing poly(vinyl pyrrolidone) (PVP) or PVA as stabilizer. PVA was most effective in stabilizing the w/o/w emulsion. Perfectly spherical microspheres were produced, with high protein entrapment efficiencies. These microspheres released lysozyme at an almost constant rate for approximately 28 days. The reproducibility of the w/o/w emulsion process was demonstrated by comparing particle characteristics and release profiles of three batches, prepared under similar conditions.

  2. Amphiphile Meets Amphiphile: Beyond the Polar-Apolar Dualism in Ionic Liquid/Alcohol Mixtures.

    Science.gov (United States)

    Russina, Olga; Sferrazza, Alessio; Caminiti, Ruggero; Triolo, Alessandro

    2014-05-15

    The mesoscopic morphology of binary mixtures of ethylammonium nitrate (EAN), the protic ionic liquid par excellence, and methanol is explored using neutron/X-ray diffraction and computational techniques. Both compounds are amphiphilic and characterized by an extended hydrogen bonding network: surprisingly, though macroscopically homogeneous, these mixtures turn out to be mesoscopically highly heterogeneous. Our study reveals that even in methanol-rich mixtures, a wide distribution of clusters exists where EAN preserves its bulk, sponge-like morphology. Accordingly methanol does not succeed in fully dissociating the ionic liquid that keeps on organizing in a bulk-like fashion. This behavior represents the premises to the more dramatic phenomenology observed with longer alcohols that eventually phase separate from EAN. These results challenge the commonly accepted polar and apolar moieties segregation in ionic liquids/molecular liquids mixtures and the current understanding of technologically relevant solvation processes.

  3. 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

    2015-02-02

    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.

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

    Science.gov (United States)

    2015-01-01

    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, 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

  5. Amphiphilic invertible polymers: Self-assembly into functional materials driven by environment polarity

    Science.gov (United States)

    Hevus, Ivan

    Stimuli-responsive polymers adapt to environmental changes by adjusting their chain conformation in a fast and reversible way. Responsive polymeric materials have already found use in electronics, coatings industry, personal care, and bio-related areas. The current work aims at the development of novel responsive functional polymeric materials by manipulating environment-dependent self-assembly of a new class of responsive macromolecules strategically designed in this study,—amphiphilic invertible polymers (AIPs). Environment-dependent micellization and self-assembly of three different synthesized AIP types based on poly(ethylene glycol) as a hydrophilic fragment and varying hydrophobic constituents was demonstrated in polar and nonpolar solvents, as well as on the surfaces and interfaces. With increasing concentration, AIP micelles self-assemble into invertible micellar assemblies composed of hydrophilic and hydrophobic domains. Polarity-responsive properties of AIPs make invertible micellar assemblies functional in polar and nonpolar media including at interfaces. Thus, invertible micellar assemblies solubilize poorly soluble substances in their interior in polar and nonpolar solvents. In a polar aqueous medium, a novel stimuli-responsive mechanism of drug release based on response of AIP-based drug delivery system to polarity change upon contact with the target cell has been established using invertible micellar assemblies loaded with curcumin, a phytochemical drug. In a nonpolar medium, invertible micellar assemblies were applied simultaneously as nanoreactors and stabilizers for size-controlled synthesis of silver nanoparticles stable in both polar and nonpolar media. The developed amphiphilic nanosilver was subsequently used as seeds to promote anisotropic growth of CdSe semiconductor nanoparticles that have potential in different applications ranging from physics to medicine. Amphiphilic invertible polymers were shown to adsorb on the surface of silica

  6. Sugar-based amphiphilic polymers for biomedical applications: from nanocarriers to therapeutics.

    Science.gov (United States)

    Gu, Li; Faig, Allison; Abdelhamid, Dalia; Uhrich, Kathryn

    2014-10-21

    Various therapeutics exhibit unfavorable physicochemical properties or stability issues that reduce their in vivo efficacy. Therefore, carriers able to overcome such challenges and deliver therapeutics to specific in vivo target sites are critically needed. For instance, anticancer drugs are hydrophobic and require carriers to solubilize them in aqueous environments, and gene-based therapies (e.g., siRNA or pDNA) require carriers to protect the anionic genes from enzymatic degradation during systemic circulation. Polymeric micelles, which are self-assemblies of amphiphilic polymers (APs), constitute one delivery vehicle class that has been investigated for many biomedical applications. Having a hydrophobic core and a hydrophilic shell, polymeric micelles have been used as drug carriers. While traditional APs are typically comprised of nondegradable block copolymers, sugar-based amphiphilic polymers (SBAPs) synthesized by us are comprised of branched, sugar-based hydrophobic segments and a hydrophilic poly(ethylene glycol) chain. Similar to many amphiphilic polymers, SBAPs self-assemble into polymeric micelles. These nanoscale micelles have extremely low critical micelle concentrations offering stability against dilution, which occurs with systemic administration. In this Account, we illustrate applications of SBAPs for anticancer drug delivery via physical encapsulation within SBAP micelles and chemical conjugation to form SBAP prodrugs capable of micellization. Additionally, we show that SBAPs are excellent at stabilizing liposomal delivery systems. These SBAP-lipid complexes were developed to deliver hydrophobic anticancer therapeutics, achieving preferential uptake in cancer cells over normal cells. Furthermore, these complexes can be designed to electrostatically complex with gene therapies capable of transfection. Aside from serving as a nanocarrier, SBAPs have also demonstrated unique bioactivity in managing atherosclerosis, a major cause of cardiovascular

  7. 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.

  8. Ammonium amphiphiles carrying mesogenic units : synthesis, properties, applications

    NARCIS (Netherlands)

    Everaars, M.D.

    1997-01-01

    When the structural characteristics of amphiphiles and thermotropic liquid crystals are combined in one molecule i.e. a polar headgroup with apolar tails and mesogenic units, compounds are obtained which can exhibit both thermotropic and lyotropic mesomorphism. This class of compounds is

  9. Loading of Vesicles into Soft Amphiphilic Nanotubes using Osmosis

    NARCIS (Netherlands)

    Erne, Petra M.; van Bezouwen, Laura S.; Stacko, Peter; van Dtjken, Derk Jan; Chen, Jiawen; Stuart, Marc C. A.; Boekema, Eghert J.; Feringa, Ben L.

    2015-01-01

    The facile assembly of higher-order nanoarchitectures from simple building blocks is demonstrated by the loading of vesicles into soft amphiphilic nanotubes using osmosis. The nanotubes are constructed from rigid interdigitated bilayers which are capped with vesicles comprising phospholipid-based

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

    NARCIS (Netherlands)

    Werkman, P.J; Schouten, A.J.

    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.

  11. Facially amphiphilic thiol capped gold and silver nanoparticles

    Indian Academy of Sciences (India)

    Wintec

    *For correspondence. Also at the Chemical Biology Unit,. Jawaharlal Nehru Centre for Advanced Scientific Research,. Bangalore 560 064. Facially amphiphilic thiol capped gold and silver nanoparticles. †. SHREEDHAR BHAT a and UDAY MAITRA*. Department of Organic Chemistry, Indian Institute of Science, Bangalore ...

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

    International Nuclear Information System (INIS)

    Matsubara, Eriko; Harada, Kouji; Inoue, Kayoko; Koizumi, Akio

    2006-01-01

    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 (EC 5 : 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 (EC 5 : 19.1 ± 17.3). Nonionic amphiphiles did not affect BWS. The longer-chain perfluorinated carboxylates PFNA and PFDA were more potent than PFOA (EC 5 : 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

  13. Nucleic acid amphiphiles : synthesis and self-assembled nanostructures

    NARCIS (Netherlands)

    Kwak, Minseok; Herrmann, Andreas; Clever, Guido; Mao, Chengde; Shionoya, Mitsuhiko; Stulz, Eugen

    2011-01-01

    This review provides an overview of a relatively new class of bio-conjugates, DNA amphiphiles, which consist of oligonucleotides covalently bonded to synthetic hydrophobic units. The reader will find the basic principles for the structural design and preparation methods of the materials. Moreover,

  14. On the slowdown mechanism of water dynamics around small amphiphiles

    NARCIS (Netherlands)

    Homsi Brandeburgo, W.; Thijmen van der Post, S.; Meijer, E.J.; Ensing, B.

    2015-01-01

    Aqueous solvation of small amphiphilic molecules exhibits a unique and complex dynamics, that is only partially understood. A recent series of studies on the hydration of small organic compounds, such as tetramethylurea (TMU), trimethylamine N-oxide (TMAO) and urea, has provided strong evidence of a

  15. Hydrophobicity and thermodynamic response for aqueous solutions of amphiphiles

    Science.gov (United States)

    Zemánková, Katerina; Troncoso, Jacobo; Cerdeiriña, Claudio A.; Romaní, Luis; Anisimov, Mikhail A.

    2016-06-01

    The anomalous behavior of aqueous solutions of amphiphiles in the water-rich region is analyzed via a phenomenological approach that utilizes the isobaric heat capacity Cp as an experimental probe. We report extensive data for solutions of 14 amphiphiles as a function of temperature at atmospheric pressure. Beyond that, Cp data but also isobaric thermal expansivities and isothermal compressibilities for three solutions of tert-butanol as a function of both temperature and pressure are presented. Results rule out the possibility that the observed phenomenology is associated with the anomalous thermodynamics of pure water. Indeed, our Cp data, quantitatively consistent with recent spectroscopic analyses, suggest that water-mediated interactions between the nonpolar parts of amphiphiles are at the origin of anomalies, with the effects of such "hydrophobic aggregation" being observed at mole fractions as small as 0.01. Physicochemical details like the size, the electronic charge distribution and the geometry of amphiphile molecules as well as third-order derivatives of the Gibbs energy and the associated Koga lines support the above claims while they further contribute to characterizing the role of hydrophobicity in these phenomena. Progress with a view to gain a deeper, more concrete understanding remains.

  16. Biocompatible Amphiphilic Hydrogel-Solid Dimer Particles as Colloidal Surfactants.

    Science.gov (United States)

    Chen, Dong; Amstad, Esther; Zhao, Chun-Xia; Cai, Liheng; Fan, Jing; Chen, Qiushui; Hai, Mingtan; Koehler, Stephan; Zhang, Huidan; Liang, Fuxin; Yang, Zhenzhong; Weitz, David A

    2017-12-26

    Emulsions of two immiscible liquids can slowly coalesce over time when stabilized by surfactant molecules. Pickering emulsions stabilized by colloidal particles can be much more stable. Here, we fabricate biocompatible amphiphilic dimer particles using a hydrogel, a strongly hydrophilic material, and achieve large contrast in the wetting properties of the two bulbs, resulting in enhanced stabilization of emulsions. We generate monodisperse single emulsions of alginate and shellac solution in oil using a flow-focusing microfluidics device. Shellac precipitates from water and forms a solid bulb at the periphery of the droplet when the emulsion is exposed to acid. Molecular interactions result in amphiphilic dimer particles that consist of two joined bulbs: one hydrogel bulb of alginate in water and the other hydrophobic bulb of shellac. Alginate in the hydrogel compartment can be cross-linked using calcium cations to obtain stable particles. Analogous to surfactant molecules at the interface, the resultant amphiphilic particles stand at the water/oil interface with the hydrogel bulb submerged in water and the hydrophobic bulb in oil and are thus able to stabilize both water-in-oil and oil-in-water emulsions, making these amphiphilic hydrogel-solid particles ideal colloidal surfactants for various applications.

  17. Anti-inflammatory polymersomes of redox-responsive polyprodrug amphiphiles with inflammation-triggered indomethacin release characteristics.

    Science.gov (United States)

    Tan, Jiajia; Deng, Zhengyu; Liu, Guhuan; Hu, Jinming; Liu, Shiyong

    2018-03-21

    Inflammation serves as a natural defense mechanism to protect living organisms from infectious diseases. Nonsteroidal anti-inflammatory drugs (NSAIDs) can help relieve inflammatory reactions and are clinically used to treat pain, fever, and inflammation, whereas long-term use of NSAIDs may lead to severe side effects including gastrointestinal damage and cardiovascular toxicity. Therefore, it is of increasing importance to configure new dosing strategies and alleviate the side effects of NSAIDs. Towards this goal, glutathione (GSH)-responsive disulfide bonds and hydrogen peroxide (H 2 O 2 )-reactive phenylboronic ester linkages were utilized as triggering moieties in this work to design redox-responsive prodrug monomers and polyprodrug amphiphiles based on indomethacin (IND) drug. Note that IND is a widely prescribed NSAID in the clinic. Starting from three types of redox-reactive IND prodrug monomers, redox-responsive polyprodrug amphiphiles were synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerizations of prodrug monomers using poly(ethylene oxide) (PEO)-based macroRAFT agent. The resultant polyprodrug amphiphiles with high IND loading contents (>33 wt%) could self-assemble into polymersomes with PEO shielding coronas and redox-responsive bilayer membranes composed of IND prodrugs. Upon incubation with GSH or H 2 O 2 , controlled release of intact IND in the active form from polyprodrug polymersomes was actuated by GSH-mediated disulfide cleavage reaction and H 2 O 2 -mediated oxidation of phenylboronic ester moieties, respectively, followed by self-immolative degradation events. Furthermore, in vitro studies at the cellular level revealed that redox-responsive polymersomes could efficiently relieve inflammatory responses induced by lipopolysaccharide (LPS) in RAW264.7 macrophage cells. Copyright © 2018. Published by Elsevier Ltd.

  18. 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

  19. 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.

  20. 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.   

  1. Disassembly Control of Saccharide-Based Amphiphiles Driven by Electrostatic Repulsion.

    Science.gov (United States)

    Yamada, Taihei; Kokado, Kenta; Sada, Kazuki

    2017-03-14

    According to the design of disassembly using electrostatic repulsion, novel amphiphiles consisting of a lipophilic ion part and a hydrophilic saccharide part were synthesized via the facile copper-catalyzed click reaction, and their molecular assemblies in water and chloroform were studied. The amphiphiles exhibited a molecular orientation opposite to that of the conventional amphiphiles in each case. ζ Potential measurements indicated that the lipophilic ion part is exposed outside in chloroform. The size of a solvophobic part in the amphiphiles dominates the size of an assembling structure; that is, in water, these amphiphiles tethering different lengths of the saccharide part exhibited almost identical assembling size, whereas in chloroform, the size depends on the length of the saccharide part in the amphiphiles.

  2. Adsorption of different amphiphilic molecules onto polystyrene latices.

    Science.gov (United States)

    Jódar-Reyes, A B; Ortega-Vinuesa, J L; Martín-Rodríguez, A

    2005-02-15

    In order to know the influence of the surface characteristics and the chain properties on the adsorption of amphiphilic molecules onto polystyrene latex, a set of experiments to study the adsorption of ionic surfactants, nonionic surfactants and an amphiphilic synthetic peptide on different latex dispersions was performed. The adsorbed amount versus the equilibrium surfactant concentration was determined. The main adsorption mechanism was the hydrophobic attraction between the nonpolar tail of the molecule and the hydrophobic regions of the latex surface. This attraction overcame the electrostatic repulsion between chains and latex surface with identical charge sign. However, the electrostatic interactions chain-surface and chain-chain also played a role. General patterns for the adsorption of ionic chains on charged latex surfaces could be established. Regarding the shape, the isotherms presented different plateaus corresponding to electrostatic effects and conformational changes. The surfactant size also affects the adsorption results: the higher the hydrophilic moiety in the surfactant molecule the lower the adsorbed amount.

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

    International Nuclear Information System (INIS)

    Moutard, Stephane

    2003-01-01

    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

  4. Preparation and self-folding of amphiphilic DNA origami.

    Science.gov (United States)

    Zhou, Chao; Wang, Dianming; Dong, Yuanchen; Xin, Ling; Sun, Yawei; Yang, Zhongqiang; Liu, Dongsheng

    2015-03-01

    Amphiphilic DNA origami is prepared by dressing multiple hydrophobic molecules on a rectangular single layer DNA origami, which is then folded or coupled in sandwich-like structures with two outer DNA origami layer and one inner hydrophobic molecules layer. The preference to form different kinds of structures could be tailored by rational design of DNA origami. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Amphiphilic cationic peptides mediate cell adhesion to plastic surfaces.

    Science.gov (United States)

    Rideout, D C; Lambert, M; Kendall, D A; Moe, G R; Osterman, D G; Tao, H P; Weinstein, I B; Kaiser, E T

    1985-09-01

    Four amphiphilic peptides, each with net charges of +2 or more at neutrality and molecular weights under 4 kilodaltons, were found to mediate the adhesion of normal rat kidney fibroblasts to polystyrene surfaces. Two of these peptides, a model for calcitonin (peptide 1, MCT) and melittin (peptide 2, MEL), form amphiphilic alpha-helical structures at aqueous/nonpolar interfaces. The other two, a luteinizing hormone-releasing hormone model (peptide 3, LHM) and a platelet factor model (peptide 4, MPF) form beta-strand structures in amphiphilic environments. Although it contains only 10 residues, LHM mediated adhesion to surfaces coated with solutions containing as little as 10 pmoles/ml of peptide. All four of these peptides were capable of forming monolayers at air-buffer interfaces with collapse pressures greater than 20 dynes/cm. None of these four peptides contains the tetrapeptide sequence Arg-Gly-Asp-Ser, which has been associated with fibronectin-mediated cell adhesion. Ten polypeptides that also lacked the sequence Arg-Gly-Asp-Ser but were nonamphiphilic and/or had net charges less than +2 at neutrality were all incapable of mediating cell adhesion (Pierschbacher and Ruoslahti, 1984). The morphologies of NRK cells spread on polystyrene coated with peptide LHM resemble the morphologies on fibronectin-coated surfaces, whereas cells spread on surfaces coated with MCT or MEL exhibit strikingly different morphologies. The adhesiveness of MCT, MEL, LHM, and MPF implies that many amphiphilic cationic peptides could prove useful as well defined adhesive substrata for cell culture and for studies of the mechanism of cell adhesion.

  6. 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.

  7. 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

    2013-02-07

    Polymeric films with nanoscale networks were prepared by selectively swelling an amphiphilic diblock copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), with the CO(2)-expanded liquid (CXL), CO(2)-methanol. The phase behavior of the CO(2)-methanol system was investigated by both theoretical calculation and experiments, revealing that methanol can be expanded by CO(2), forming homogeneous CXL under the experimental conditions. When treated with the CO(2)-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.

  8. Synthesis of Well-defined Amphiphilic Block Copolymers by Organotellurium-Mediated Living Radical Polymerization (TERP).

    Science.gov (United States)

    Kumar, Santosh; Changez, Mohammad; Murthy, C N; Yamago, Shigeru; Lee, Jae-Suk

    2011-10-04

    Low-molecular weight amphiphilic diblock copolymers, polystyrene-block-poly (2-vinylpyridine) (PS-b-P2VP), and (P2VP-b-PS) with different block ratios were synthesized for the first time via organotellurium-mediated living radical polymerization (TERP). For both the homo- and block copolymerizations, good agreement between the theoretical, and experimental molecular weights was found with nearly 100% yield in every case. The molecular weight distribution for all the samples ranged between 1.10 and 1.24, which is well below the theoretical lower limit of 1.50 for a conventional free radical polymerization. Furthermore, a very simple approach to producing highly dense arrays of titania nanoparticles (TiO2 ) is presented using a site-selective reaction of titanium tetraisopropoxide within the P2VP domains of micellar film of P2VP-b-PS in toluene through the sol-gel method. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Tuning Amphiphilicity of Particles for Controllable Pickering Emulsion

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    2016-11-01

    Full Text Available Pickering emulsions with the use of particles as emulsifiers have been extensively used in scientific research and industrial production due to their edge in biocompatibility and stability compared with traditional emulsions. The control over Pickering emulsion stability and type plays a significant role in these applications. Among the present methods to build controllable Pickering emulsions, tuning the amphiphilicity of particles is comparatively effective and has attracted enormous attention. In this review, we highlight some recent advances in tuning the amphiphilicity of particles for controlling the stability and type of Pickering emulsions. The amphiphilicity of three types of particles including rigid particles, soft particles, and Janus particles are tailored by means of different mechanisms and discussed here in detail. The stabilization-destabilization interconversion and phase inversion of Pickering emulsions have been successfully achieved by changing the surface properties of these particles. This article provides a comprehensive review of controllable Pickering emulsions, which is expected to stimulate inspiration for designing and preparing novel Pickering emulsions, and ultimately directing the preparation of functional materials.

  10. Codelivery for Paclitaxel and Bcl-2 Conversion Gene by PHB-PDMAEMA Amphiphilic Cationic Copolymer for Effective Drug Resistant Cancer Therapy.

    Science.gov (United States)

    Wang, Xiaoyuan; Liow, Sing Shy; Wu, Qiaoqiong; Li, Chuang; Owh, Cally; Li, Zibiao; Loh, Xian Jun; Wu, Yun-Long

    2017-11-01

    Antiapoptotic Bcl-2 protein's upregulated expression is a key reason for drug resistance leading to failure of chemotherapy. In this report, a series of biocompatible amphiphilic cationic poly[(R)-3-hydroxybutyrate] (PHB)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) copolymer, comprising hydrophobic PHB block and cationic PDMAEMA block, is designed to codeliver hydrophobic chemotherapeutic paclitaxel and Bcl-2 converting gene Nur77/ΔDBD with enhanced stability, due to the micelle formation by hydrophobic PHB segment. This copolymer shows less toxicity but similar gene transfection efficiency to polyethyenimine (25k). More importantly, this codelivery approach by PHB-PDMAEMA leads to increased drug resistant HepG2/Bcl-2 cancer cell death, by increased expression of Nur77 proteins in the Bcl-2 present intracellular mitochondria. This work signifies for the first time that cationic amphiphilic PHB-b-PDMAEMA copolymers can be utilized for the drug and gene codelivery to drug resistant cancer cells with high expression of antiapoptosis Bcl-2 protein and the positive results are encouraging for the further design of codelivery platforms for combating drug resistant cancer cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Effect of montmorillonite clay on flax fabric reinforced poly lactic acid composites with amphiphilic additives

    CSIR Research Space (South Africa)

    Kumar, R

    2010-01-01

    Full Text Available 5083263; fax: +27 41 5832325. Composites: Part A xxx (2010) xxx–xxx Contents lists availabl tes ev E-mail address: krrakesh72@gmail.com (R. Kumar). strength and stiffness, dimensional stability, and thermal proper- ties [1]. But finite nature.... Chemical treatments of natural fiber for use in natural fiber-reinforced composites: a review. J Polym Environ 2007;15:25–33. [15] Pothan LA, Thomas S, Groeninckx G. The role of fibre/matrix interactions on the dynamic mechanical properties...

  12. 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

  13. Membrane behavior as influenced by partitioning of amphiphiles during drying : a comparative study in anhydrobiotic plant systems

    NARCIS (Netherlands)

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

    2002-01-01

    During cellular desiccation, reduction in volume can in principle cause amphiphilic compounds to partition from the cytoplasm into membranes, with structural perturbance as the result. Here, we studied the effect of partitioning of endogenous amphiphiles on membrane surface dynamics in

  14. 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

  15. Maltose-neopentyl glycol (MNG) amphiphiles for solubilization, stabilization and crystallization of membrane proteins

    DEFF Research Database (Denmark)

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

    2010-01-01

    proteins remain difficult to study owing to a lack of suitable detergents. We introduce a class of amphiphiles, each built around a central quaternary carbon atom derived from neopentyl glycol, with hydrophilic groups derived from maltose. Representatives of this maltose-neopentyl glycol (MNG) amphiphile...

  16. Hemifluorinated maltose-neopentyl glycol (HF-MNG) amphiphiles for membrane protein stabilisation.

    Science.gov (United States)

    Cho, Kyung Ho; Byrne, Bernadette; Chae, Pil Seok

    2013-03-04

    SOAP OPERA: Fluorinated amphiphile F4-MNG confers greater stability on Rhodobacter capsulatus superassembly relative to conventional detergents and nonfluorinated MNGs. Such amphiphiles are attractive as tools for membrane science because of their ease of preparation and structure variation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Trapping of polycyclic aromatic hydrocarbons by amphiphilic cyclodextrin functionalized polypropylene nonwovens

    DEFF Research Database (Denmark)

    Lumholdt, Ludmilla; Nielsen, Ronnie Bo Højstrup; Larsen, Kim Lambertsen

    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....

  18. H-shaped supra-amphiphiles based on a dynamic covalent bond.

    Science.gov (United States)

    Wang, Guangtong; Wang, Chao; Wang, Zhiqiang; Zhang, Xi

    2012-10-16

    The imine bond, a kind of dynamic covalent bond, is used to bind two bolaform amphiphiles together with spacers, yielding H-shaped supra-amphiphiles. Micellar aggregates formed by the self-assembly of the H-shaped supra-amphiphiles are observed. When pH is tuned down from basic to slightly acidic, the benzoic imine bond can be hydrolyzed, leading to the dissociation of H-shaped supra-amphiphiles. Moreover, H-shaped supra-amphiphiles have a lower critical micelle concentration than their building blocks, which is very helpful in enhancing the stability of the benzoic imine bond being hydrolyzed by acid. The surface tension isotherms of the H-shaped supra-amphiphiles with different spacers indicate their twisty conformation at a gas-water interface. The study of H-shaped supra-amphiphiles can enrich the family of amphiphiles, and moreover, the pH-responsiveness may make them apply to controlled or targetable drug delivery in a biological environment.

  19. Intracellular degradation of microspheres based on cross-linked dextran hydrogels or amphiphilic block copolymers: A comparative Raman microscopy study

    Science.gov (United States)

    van Manen, Henk-Jan; van Apeldoorn, Aart A; Verrijk, Ruud; van Blitterswijk, Clemens A; Otto, Cees

    2007-01-01

    Micro- and nanospheres composed of biodegradable polymers show promise as versatile devices for the controlled delivery of biopharmaceuticals. Whereas important properties such as drug release profiles, biocompatibility, and (bio)degradability have been determined for many types of biodegradable particles, information about particle degradation inside phagocytic cells is usually lacking. Here, we report the use of confocal Raman microscopy to obtain chemical information about cross-linked dextran hydrogel microspheres and amphiphilic poly(ethylene glycol)-terephthalate/poly(butylene terephthalate) (PEGT/PBT) microspheres inside RAW 264.7 macrophage phagosomes. Using quantitative Raman microspectroscopy, we show that the dextran concentration inside phagocytosed dextran microspheres decreases with cell incubation time. In contrast to dextran microspheres, we did not observe PEGT/PBT microsphere degradation after 1 week of internalization by macrophages, confirming previous studies showing that dextran microsphere degradation proceeds faster than PEGT/PBT degradation. Raman microscopy further showed the conversion of macrophages to lipid-laden foam cells upon prolonged incubation with both types of microspheres, suggesting that a cellular inflammatory response is induced by these biomaterials in cell culture. Our results exemplify the power of Raman microscopy to characterize microsphere degradation in cells and offer exciting prospects for this technique as a noninvasive, label-free optical tool in biomaterials histology and tissue engineering. PMID:17722552

  20. Morphology-Variable Aggregates Prepared from Cholesterol-Containing Amphiphilic Glycopolymers: Their Protein Recognition/Adsorption and Drug Delivery Applications

    Directory of Open Access Journals (Sweden)

    Zhao Wang

    2018-02-01

    Full Text Available In this study, a series of diblock glycopolymers, poly(6-O-methacryloyl-d-galactopyranose-b-poly(6-cholesteryloxyhexyl methacrylate (PMAgala-b-PMAChols, with cholesterol/galactose grafts were prepared through a sequential reversible addition-fragmentation chain transfer (RAFT polymerization and deprotection process. The glycopolymers could self-assemble into aggregates with various morphologies depending on cholesterol/galactose-containing block weight ratios, as determined by transmission electronic microscopy (TEM and dynamic laser light scattering (DLS. In addition, the lectin (Ricinus communis agglutinin II, RCA120 recognition and bovine serum albumin (BSA adsorption of the PMAgala-b-PMAChol aggregates were evaluated. The SK-Hep-1 tumor cell inhibition properties of the PMAgala-b-PMAChol/doxorubicin (DOX complex aggregates were further examined in vitro. Results indicate that the PMAgala-b-PMAChol aggregates with various morphologies showed different interaction/recognition features with RCA120 and BSA. Spherical aggregates (d ≈ 92 nm possessed the highest RCA120 recognition ability and lowest BSA protein adsorption. In addition, the DOX-loaded spherical complex aggregates exhibited a better tumor cell inhibition property than those of nanofibrous complex aggregates. The morphology-variable aggregates derived from the amphiphilic glycopolymers may serve as multifunctional biomaterials with biomolecular recognition and drug delivery features.

  1. 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......: the medium composition in terms of ionic strengths and the medium physical parameters, such as temperature, significantly influence the formation of structures, as well as their subsequent stability. In addition, membranes composed of a single amphiphile type seem to be implausible as no potential amphiphile...... source studied to date can supply one single type of amphiphile at concentrations conducive to self-assembly. Mixtures of single-chain amphiphiles were therefore proposed to better model primitive membranes and potentially enhance their structural integrity1-3. Recently, we have established that complex...

  2. Supra-amphiphiles: a new bridge between colloidal science and supramolecular chemistry.

    Science.gov (United States)

    Kang, Yuetong; Liu, Kai; Zhang, Xi

    2014-06-03

    In addition to conventional amphiphiles, an emerging research area is supra-amphiphiles, which are constructed on the basis of noncovalent interactions and dynamic covalent bonds. In this feature article, we have provided a general introduction to the concept, design principles, and topologies of supra-amphiphiles, starting from some rationally tailored building blocks. In addition, we highlight some progress in the functional assembly of supra-amphiphiles, such as responsive nanoscale carriers, antibacterial and antitumor agents, fluorescent-based chemical sensors, and enzyme mimics. The supra-amphiphile is a new bridge between colloidal science and supramolecular chemistry, and it is a field where we can make full use of our imaginative power.

  3. Self-assembly of active amphiphilic Janus particles

    Science.gov (United States)

    Mallory, S. A.; Alarcon, F.; Cacciuto, A.; Valeriani, C.

    2017-12-01

    In this article, we study the phenomenology of a two dimensional dilute suspension of active amphiphilic Janus particles. We analyze how the morphology of the aggregates emerging from their self-assembly depends on the strength and the direction of the active forces. We systematically explore and contrast the phenomenologies resulting from particles with a range of attractive patch coverages. Finally, we illustrate how the geometry of the colloids and the directionality of their interactions can be used to control the physical properties of the assembled active aggregates and suggest possible strategies to exploit self-propulsion as a tunable driving force for self-assembly.

  4. Liquid-solid extraction of metallic cations by cationic amphiphiles

    International Nuclear Information System (INIS)

    Mueller, Wolfram; Sievers, Torsten K.; Zemb, Thomas; Diat, Olivier; Sievers, Torsten K.; Dejugnat, Christophe

    2012-01-01

    In the field of selective metal ion separation, liquid-liquid extraction is usually conducted through an emulsion mixing of hydrophobic complexants dispersed in an organic phase and acidic water containing the ionic species. Recently, it has been shown that amphiphilic complexants could influence strongly extraction efficiency by enhancing the interfacial interaction between the metal ion in the aqueous and the complexant in the organic phase. Moreover, these amphiphiles can also substitute the organic phase if an appropriate aliphatic chain is chosen. The dispersion of such amphiphilic complexants in an aqueous solution of salt mixtures is not only attractive for studying specific interactions but also to better the understanding of complex formation in aqueous solution of multivalent metal ions, such as lanthanides and actinides. This understanding is of potential interest for a broad range of industries including purification of rare earth metals and pollute treatment e.g. of fission byproducts. This principle can also be applied to liquid-solid extraction, where the final state of the separation is a solid phase containing the selectively extracted ions. Indeed, a novel solid-liquid extraction method exploits the selective precipitation of metal ions from an aqueous salt mixture using a cationic surfactant, below its Krafft point (temperature below which the long aliphatic chains of surfactant crystallize). This technique has been proven to be highly efficient for the separation of actinides and heavy metal using long chain ammonium or pyridinium amphiphiles. The most important point in this process is the recognition of cationic metal ions by cationic surfactants. By computing the free energy of the polar head group per micelle as a function of the different counter-anions, we have demonstrated for the first time that different interactions exist between the micellar surface and the ions. These interactions depend on the nature of the cation but also on

  5. Differential thermodynamic signature of carbon nanomaterials using amphiphilic micellar probe

    Science.gov (United States)

    Bhattacharyya, Tamoghna; Dasgupta, Anjan Kr

    2018-04-01

    The thermodynamic signature of single-wall carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs) and reduced graphene oxide (rG-O) using amphiphilic micellar probe has been explored. The study reveals an intricate correlation between nano-surface topology and calorimetric profile of SWCNTs, MWCNTs and rG-O. The critical micelle concentration (CMC) is found to be sensitive to the topological diversity of nanomaterials. The study explores a thermodynamic approach to characterize the nano-surface topology of SWCNTs, MWCNTs and graphene surface.

  6. Control of in vivo disposition and immunogenicity of polymeric micelles by adjusting poly(sarcosine) chain lengths on surface

    Science.gov (United States)

    Kurihara, Kensuke; Ueda, Motoki; Hara, Isao; Ozeki, Eiichi; Togashi, Kaori; Kimura, Shunsaku

    2017-07-01

    Four kinds of A3B-type amphiphilic polydepsipeptides, (poly(sarcosine))3- b-poly( l-lactic acid) (the degree of polymerization of poly(sarcosine) are 10, 33, 55, and 85; S10 3 , S33 3 , S55 3 , and S85 3 ) were synthesized to prepare core-shell type polymeric micelles. Their in vivo dispositions and stimulations to trigger immune system to produce IgM upon multiple administrations to mice were examined. With increasing poly(sarcosine) chain lengths, the hydrophilic shell became thicker and the surface density at the most outer surface decreased on the basis of dynamic and static light scattering measurements. These two physical elements of polymeric micelles elicited opposite effects on the immune response in light of the chain length therefore to show an optimized poly(sarcosine) chain length existing between 33mer and 55mer to suppress the accelerated blood clearance phenomenon associated with polymeric micelles.

  7. Novel Anti-Biofouling Soft Contact Lens: l-Cysteine Conjugated Amphiphilic Conetworks via RAFT and Thiol-Ene Click Chemistry.

    Science.gov (United States)

    Zhang, Chengfeng; Liu, Ziyuan; Wang, Haiye; Feng, Xiaofeng; He, Chunju

    2017-07-01

    A unique l-cysteine conjugated antifouling amphiphilic conetwork (APCN) is synthesized through end-crosslinking of well-defined triblock copolymers poly(allyl methacrylate)-b-poly(ethylene glycol)-b-poly(allyl methacrylate) via a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and thiol-ene "click" chemistry. The synthesized poly(ethylene glycol) macro-RAFT agent initiates the polymerization of allyl methacrylate in a controlled manner. The vinyl pendant groups of the precursor partially conjugate with l-cysteine and the rest fully crosslink with mercaptopropyl-containing siloxane via thiol-ene click chemistry under UV irradiation into APCNs, which show distinguished properties, that is, excellent biocompatibility, more than 39.6% water content, 101 barrers oxygen permeability, optimized mechanical properties, and more than 93% visible light transmittance. What's more, the resultant APCNs exhibit eminent resistance to protein adsorption, where the bovine serum albumin and lysozyme adsorption are decreased to 12 and 21 µg cm -2 , respectively. The outstanding properties of APCNs depend on the RAFT controlled method, which precisely designs the hydrophilic/hydrophobic segments and eventually greatly improves the crosslinking efficiency and homogeneity. Meantime, the l-cysteine monolayer can effectively reduce the surface hydrophobicity and prevent protein adsorption, which exhibits the viability for antifouling surface over and under ophthalmic devices, suggesting a promising soft contact lens. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. 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

  9. 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

  10. 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

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

    International Nuclear Information System (INIS)

    Travelet, Christophe; Stemmelen, Mylène; Lapinte, Vincent; Dubreuil, Frédéric; Robin, Jean-Jacques

    2013-01-01

    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 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 19 to 19.2 nm for C 57 ). Furthermore, increasing the polyoxazoline (i.e., hydrophilic block) length leads to a moderate linear increase of the D 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 copolymers based

  12. 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.

  13. Fabrication of supramolecular star-shaped amphiphilic copolymers for ROS-triggered drug release.

    Science.gov (United States)

    Zuo, Cai; Peng, Jinlei; Cong, Yong; Dai, Xianyin; Zhang, Xiaolong; Zhao, Sijie; Zhang, Xianshuo; Ma, Liwei; Wang, Baoyan; Wei, Hua

    2018-03-15

    Star-shaped copolymers with branched structures can form unimolecular micelles with better stability than the micelles self-assembled from conventional linear copolymers. However, the synthesis of star-shaped copolymers with precisely controlled degree of branching (DB) suffers from complicated sequential polymerizations and multi-step purification procedures, as well as repeated optimizations of polymer compositions. The use of a supramolecular host-guest pair as the block junction would significantly simplify the preparation. Moreover, the star-shaped copolymer-based unimolecular micelle provides an elegant solution to the tradeoff between extracellular stability and intracellular high therapeutic efficacy if the association/dissociation of the supramolecular host-guest joint can be triggered by the biologically relevant stimuli. For this purpose, in this study, a panel of supramolecular star-shaped amphiphilic block copolymers with 9, 12, and 18 arms were designed and fabricated by host-guest complexations between the ring-opening polymerization (ROP)-synthesized star-shaped poly(ε-caprolactone) (PCL) with 3, 4, and 6 arms end-capped with ferrocene (Fc) (PCL-Fc) and the atom transfer radical polymerization (ATRP)-produced 3-arm poly(oligo ethylene glycol) methacrylates (POEGMA) with different degrees of polymerization (DPs) of 24, 30, 47 initiated by β-cyclodextrin (β-CD) (3Br-β-CD-POEGMA). The effect of DB and polymer composition on the self-assembled properties of the five star-shaped copolymers was investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM), and fluorescence spectrometery. Interestingly, the micelles self-assembled from 12-arm star-shaped copolymers exhibited greater stability than the 9- and 18-arm formulations. The potential of the resulting supramolecular star-shaped amphiphilic copolymers as drug carriers was evaluated by an in vitro drug release study, which confirmed the ROS-triggered accelerated drug

  14. 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

    shown to be more stable than those formed by pure fatty acids. Those containing bola-amphiphile even showed encapsulation of a small hydrophilic solute (8-hydroxypyrene-1,3,6-trisulfonic-acid) suggesting a denser packing of the amphiphiles. Compression and kinetics analysis of monolayers composed...... of these amphiphiles mixtures at the air/water interface suggest that the stabilization of the structures can be attributed to two main interactions between headgroups, predominantly the formation of hydrogen bonds between protonated and deprotonated acids and then the additional electrostatic interactions between...

  15. Asymmetric and symmetric bolaform supra-amphiphiles: formation of imine bond influenced by aggregation.

    Science.gov (United States)

    Wang, Guangtong; Wu, Guanglu; Wang, Zhiqiang; Zhang, Xi

    2014-02-18

    A series of bolaform supra-amphilphiles with different symmetries were fabricated through dynamic benzoic imine bond formation. The pH dependence of imine formations of these supra-amphiphiles were characterazied. We found that the extent of the imine formation of these supra-amphiphies were different. The supra-amphiphiles with a poorer symmetry always exhibited a lower imine formation at a given pH. Therefore, the varied extent of imine bond formation indicate the different aggregations of these supra-amphilphiles, which are controlled by the molecular symmetry of the supra-amphiphiles.

  16. (CryoTransmission Electron Microscopy of Phospholipid Model Membranes Interacting with Amphiphilic and Polyphilic Molecules

    Directory of Open Access Journals (Sweden)

    Annette Meister

    2017-10-01

    Full Text Available Lipid membranes can incorporate amphiphilic or polyphilic molecules leading to specific functionalities and to adaptable properties of the lipid bilayer host. The insertion of guest molecules into membranes frequently induces changes in the shape of the lipid matrix that can be visualized by transmission electron microscopy (TEM techniques. Here, we review the use of stained and vitrified specimens in (cryoTEM to characterize the morphology of amphiphilic and polyphilic molecules upon insertion into phospholipid model membranes. Special emphasis is placed on the impact of novel synthetic amphiphilic and polyphilic bolalipids and polymers on membrane integrity and shape stability.

  17. Synthesis and Application of a New Amphiphilic Antioxidant.

    Science.gov (United States)

    Soliman, Hanaa M; Arafat, Shaker M; Basuny, Amany M; Shattory, Y El-

    2017-11-01

    A new amphiphilic antioxidant (tannyl stearate) derived from reaction of tannic acid with stearic acid was synthesized in order to improve tannic acid solubility in lipid materials. This reaction gives many products having different degree of esterification (tannyl mono, di, tri, tetra, penta, hexa, hepta……stearate) which were separated using silica gel column chromatography and tentative identification was carried out using thin layer chromatography (TLC). The intrinsic viscosities (η) were used to differentiate between the different molecular weight of the produced esters 1) . Tannyl penta stearate is assumed to be the most suitable amphiphilic antioxidant derivative, where those derivatives with less degree of esterification would be less soluble in fat, and those of higher degree of esterification would exhaust more hydroxyl group that cause decreases of antioxidant activity. The structure of tannyl penta stearate was approved depending on its chemical analysis and spectral data (IR, H 1 NMR,). The emulsification power of tannyl penta stearate was then determined according to method described by El-Sukkary et al. 2) , in order to prove its amphiphilic property. Then tannyl penta stearate was tested for its antioxidant and radical scavenging activities in three different manners, those are, lipid oxidation in sunflower oil using Rancimat, (DPPH) free radical scavenging and total antioxidant activity. {Pure tannic acid (T), butylhydroxyanisol (BHA) and butylhydroxytoluene (BHT) were used as reference antioxidant radical saving compounds}. Then tannyl penta stearate was added to sunflower oil, frying process was carried out and all physicochemical parameters of the oil were considered, and compared to other reference antioxidant in order to study the effect of this new antioxidant toward oil stability. Acute oral toxicity of the tannyl penta stearate was carried out using albino mice of 21-25 g body weight to determine its safety according to the method

  18. A Novel Poly(vinylidene fluoride)-Based 4-Miktoarm Star Terpolymer: Synthesis and Self-Assembly

    KAUST Repository

    Patil, Yogesh Raghunath; Bilalis, Panagiotis; Polymeropoulos, George; Almahdali, Sarah; Hadjichristidis, Nikolaos; Rodionov, Valentin

    2018-01-01

    A well-defined amphiphilic miktoarm polymer incorporating poly(vinylidene fluoride) (PVDF), polystyrene (PS), and poly(ethylene glycol) (PEG) blocks was synthesized via a combination of atom-transfer radical polymerization (ATRP), iodine transfer radical polymerization (ITP), and copper-catalyzed azide-alkyne cycloaddition (CuAAC). Morphology and self-assembly of this star polymer were examined in organic solvents and in water. The aggregates formed in water were found to possess unusual frustrated topology due to immiscibility of PS and PVDF. The polymer was evaluated for transport of small hydrophobic molecules in water.

  19. A Novel Poly(vinylidene fluoride)-Based 4-Miktoarm Star Terpolymer: Synthesis and Self-Assembly

    KAUST Repository

    Patil, Yogesh Raghunath

    2018-03-15

    A well-defined amphiphilic miktoarm polymer incorporating poly(vinylidene fluoride) (PVDF), polystyrene (PS), and poly(ethylene glycol) (PEG) blocks was synthesized via a combination of atom-transfer radical polymerization (ATRP), iodine transfer radical polymerization (ITP), and copper-catalyzed azide-alkyne cycloaddition (CuAAC). Morphology and self-assembly of this star polymer were examined in organic solvents and in water. The aggregates formed in water were found to possess unusual frustrated topology due to immiscibility of PS and PVDF. The polymer was evaluated for transport of small hydrophobic molecules in water.

  20. 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.

  1. Amphiphilic Quantum Dots with Asymmetric, Mixed Polymer Brush Layers: From Single Core-Shell Nanoparticles to Salt-Induced Vesicle Formation

    Directory of Open Access Journals (Sweden)

    Brian R. Coleman

    2018-03-01

    Full Text Available A mixed micelle approach is used to produce amphiphilic brush nanoparticles (ABNPs with cadmium sulfide quantum dot (QD cores and surface layers of densely grafted (σ = ~1 chain/nm2 and asymmetric (fPS = 0.9 mixed polymer brushes that contain hydrophobic polystyrene (PS and hydrophilic poly(methyl methacrylate (PMAA chains (PS/PMAA-CdS. In aqueous media, the mixed brushes undergo conformational rearrangements that depend strongly on prior salt addition, giving rise to one of two pathways to fluorescent and morphologically disparate QD-polymer colloids. (A In the absence of salt, centrosymmetric condensation of PS chains forms individual core-shell QD-polymer colloids. (B In the presence of salt, non-centrosymmetric condensation of PS chains forms Janus particles, which trigger anisotropic interactions and amphiphilic self-assembly into the QD-polymer vesicles. To our knowledge, this is the first example of an ABNP building block that can form either discrete core-shell colloids or self-assembled superstructures in water depending on simple changes to the chemical conditions (i.e., salt addition. Such dramatic and finely tuned morphological variation could inform numerous applications in sensing, biolabeling, photonics, and nanomedicine.

  2. Interaction of amphiphilic drugs with human and bovine serum albumins.

    Science.gov (United States)

    Khan, Abbul Bashar; Khan, Javed Masood; Ali, Mohd Sajid; Khan, Rizwan Hasan; Kabir-Ud-Din

    2012-11-01

    To know the interaction of amphiphilic drugs nortriptyline hydrochloride (NOT) and promazine hydrochloride (PMZ) with serum albumins (i.e., human serum albumin (HSA) and bovine serum albumin (BSA)), techniques of UV-visible, fluorescence, and circular dichroism (CD) spectroscopies are used. The binding affinity is more in case of PMZ with both the serum albumins. The quenching rate constant (k(q)) values suggest a static quenching process for all the drug-serum albumin interactions. The UV-visible results show that the change in protein conformation of PMZ-serum albumin interactions are more prominent as compared to NOT-serum albumin interactions. The CD results also explain the conformational changes in the serum albumins on binding with the drugs. The increment in %α-helical structure is slightly more for drug-BSA complexes as compared to drug-HSA complexes. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Structure and reactivity in amphiphile-water micelles

    International Nuclear Information System (INIS)

    Chevalier, Yves

    1985-01-01

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

  4. Preparation and self-assembly of amphiphilic polylysine dendrons

    DEFF Research Database (Denmark)

    Mirsharghi, Sahar; Knudsen, Kenneth D.; Bagherifam, Shahla

    2016-01-01

    Polylysine dendrons with lipid tails prepared by divergent solid-phase synthesis showed self-assembling properties in aqueous solutions., Herein, we present the synthesis of new amphiphilic polylysine dendrons with variable alkyl chain lengths (C1–C18) at the C-terminal. The dendrons were...... synthesized in moderate to quantitative yields by divergent solid-phase synthesis (SPS) employing an aldehyde linker. The self-assembling properties of the dendrons in aqueous solutions were studied by small angle neutron scattering (SANS) and dynamic light scattering (DLS). The self-assembling properties...... were influenced by the length of the alkyl chain and the generation number (Gn). Increasing the temperature and concentration did not have significant impact on the hydrodynamic diameter, but the self-assembling properties were influenced by the pH value. This demonstrated the need for positively...

  5. Exciplex emission from amphiphilic polysilanes bearing ammonium moieties

    International Nuclear Information System (INIS)

    Yamaki, T.; Nakashiba, Y.; Asai, K.; Ishigure, K.; Shibata, H.

    1997-01-01

    We were the first to observe two emission bands in the visible region for some kinds of ammonium-type amphiphilic polysilanes both in solutions and in thin films. One, a broad emission band at 400-500 nm not due to a σ * →σ transition, was observed only for methylphenylsilane-based polymer solutions. The appearance of this low-energy emission is reasonably explained by considering the intramolecular exciplex formation between a Si-conjugated main chain and an ammonium site in the same monomer unit. The other, an emission band at the longer wavelength (around 560 nm), was found in the solvent-cast films where each molecule is randomly located, in addition to that observed for the solutions. This emission, which was not observed for the oriented LB films, is considered to originate from an intermolecular interaction. (orig.)

  6. 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.

  7. Modulation of Cyclodextrin Particle Amphiphilic Properties to Stabilize Pickering Emulsion.

    Science.gov (United States)

    Xi, Yongkang; Luo, Zhigang; Lu, Xuanxuan; Peng, Xichun

    2018-01-10

    Cyclodextrins have been proven to form complexes with linear oil molecules and stabilize emulsions. Amphiphilic properties of cyclodextrin particles were modulated through esterification reaction between β-cyclodextrin (β-CD) and octadecenyl succinic anhydride (ODSA) under alkaline conditions. ODS-β-CD particles with degree of substitution (DS) of 0.003, 0.011, and 0.019 were obtained. The introduced hydrophobic long chain that was linked within β-CD cavity led to the change of ODS-β-CD in terms of morphological structure, surface charge density, size, and contact angle, upon which the properties and stability of the emulsions stabilized by ODS-β-CD were highly dependent. The average diameter of ODS-β-CD particles ranged from 449 to 1484 nm. With the DS increased from 0.003 to 0.019, the contact angle and absolute zeta potential value of these ODS-β-CD particles improved from 25.7° to 47.3° and 48.1 to 62.8 mV, respectively. The cage structure of β-CD crystals was transformed to channel structure, then further to amorphous structure after introduction of the octadecenyl succinylation chain. ODS-β-CD particles exhibited higher emulsifying ability compared to β-CD. The resulting Pickering emulsions formed by ODS-β-CD particles were more stable during storage. This study investigates the ability of these ODS-β-CD particles to stabilize oil-in-water emulsions with respect to their amphiphilic character and structural properties.

  8. Silver baits for the "miraculous draught" of amphiphilic lanthanide helicates.

    Science.gov (United States)

    Terazzi, Emmanuel; Guénée, Laure; Varin, Johan; Bocquet, Bernard; Lemonnier, Jean-François; Emery, Daniel; Mareda, Jiri; Piguet, Claude

    2011-01-03

    The axial connection of flexible thioalkyls chains of variable length (n=1-12) within the segmental bis-tridentate 2-benzimidazole-8-hydroxyquinoline ligands [L12(Cn) -2 H](2-) provides amphiphilic receptors designed for the synthesis of neutral dinuclear lanthanides helicates. However, the stoichiometric mixing of metals and ligands in basic media only yields intricate mixtures of poorly soluble aggregates. The addition of Ag(I) in solution restores classical helicate architectures for n=3, with the quantitative formation of the discrete D(3) -symmetrical [Ln(2) Ag2(L12(C3) -2 H)(3) ](2+) complexes at millimolar concentration (Ln=La, Eu, Lu). The X-ray crystal structure supports the formation of [La(2) Ag(2) (L12(C3) -2 H)(3) ][OTf](2) , which exists in the solid state as infinite linear polymers bridged by S-Ag-S bonds. In contrast, molecular dynamics (MD) simulations in the gas phase and in solution confirm the experimental diffusion measurements, which imply the formation of discrete molecular entities in these media, in which the sulfur atoms of each lipophilic ligand are rapidly exchanged within the Ag(I) coordination sphere. Turned as a predictive tool, MD suggests that this Ag(I) templating effect is efficient only for n=1-3, while for n>3 very loose interactions occur between Ag(I) and the thioalkyl residues. The subsequent experimental demonstration that only 25 % of the total ligand speciation contributes to the formation of [Ln(2) Ag(2) (L12(C12) -2 H)(3) ](2+) in solution puts the bases for a rational approach for the design of amphiphilic helical complexes with predetermined molecular interfaces. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Self-assembling peptide amphiphiles and related methods for growth factor delivery

    Science.gov (United States)

    Stupp, Samuel I [Chicago, IL; Donners, Jack J. J. M.; Silva, Gabriel A [Chicago, IL; Behanna, Heather A [Chicago, IL; Anthony, Shawn G [New Stanton, PA

    2009-06-09

    Amphiphilic peptide compounds comprising one or more epitope sequences for binding interaction with one or more corresponding growth factors, micellar assemblies of such compounds and related methods of use.

  10. 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

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

    Science.gov (United States)

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

    2015-12-08

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

  12. Non-surface activity and micellization behavior of cationic amphiphilic block copolymer synthesized by reversible addition-fragmentation chain transfer process.

    Science.gov (United States)

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

    2011-08-02

    Cationic amphiphilic diblock copolymers of poly(n-butylacrylate)-b-poly(3-(methacryloylamino)propyl)trimethylammonium chloride) (PBA-b-PMAPTAC) with various hydrophobic and hydrophilic chain lengths were synthesized by a reversible addition-fragmentation chain transfer (RAFT) process. Their molecular characteristics such as surface activity/nonactivity were investigated by surface tension measurements and foam formation observation. Their micelle formation behavior and micelle structure were investigated by fluorescence probe technique, static and dynamic light scattering (SLS and DLS), etc., as a function of hydrophilic and hydrophobic chain lengths. The block copolymers were found to be non-surface active because the surface tension of the aqueous solutions did not change with increasing polymer concentration. Critical micelle concentration (cmc) of the polymers could be determined by fluorescence and SLS measurements, which means that these polymers form micelles in bulk solution, although they were non-surface active. Above the cmc, the large blue shift of the emission maximum of N-phenyl-1-naphthylamine (NPN) probe and the low micropolarity value of the pyrene probe in polymer solution indicate the core of the micelle is nonpolar in nature. Also, the high value of the relative intensity of the NPN probe and the fluorescence anisotropy of the 1,6-diphenyl-1,3,5-hexatriene (DPH) probe indicated that the core of the micelle is highly viscous in nature. DLS was used to measure the average hydrodynamic radii and size distribution of the copolymer micelles. The copolymer with the longest PBA block had the poorest water solubility and consequently formed micelles with larger size while having a lower cmc. The "non-surface activity" was confirmed for cationic amphiphilic diblock copolymers in addition to anionic ones studied previously, indicating the universality of non-surface activity nature.

  13. Amphiphilic polymer based on fluoroalkyl and PEG side chains for fouling release coating

    Science.gov (United States)

    Cong, W. W.; Wang, K.; Yu, X. Y.; Zhang, H. Q.; Lv, Z.; Gui, T. J.

    2017-12-01

    Under static conditions, fouling release coating could not express good release property to marine organisms. Amphiphilic polymer with mixture of fluorinated monomer and short side group of polyethylene glycol (PEG) was synthesized. And also we studied the ability of amphiphilic polymer to influence the surface properties and how it controlled the adhesion of marine organisms to coated surfaces. By incorporating fluorinated monomer and PEG side chain into the polymer, the effect of incorporating both polar and non-polar groups on fouling-release coating could be studied. The dry surface was characterized by three-dimensional digital microscopy and scanning electron microscopy (SEM), and the morphology of the amphiphilic fouling release coating showed just like flaky petal. The amphiphilic polymer in fouling release coating tended to reconstruct in water, and the ability was examined by static contact angle, which was smaller than the PDMS (polydimethylsiloxane) fouling release coating. Also surface energy was calculated by three solvents, and surface energy of amphiphilic fouling release coating was higher than that of the PDMS fouling release coating. To understand more about its fouling release property, seawater exposure method was adopted in gulf of Qingdao port. Fewer diatoms Navicula were found in biofilm after using amphiphilic fouling release coating. In general, coating containing both PEG and fluorinated side chain possessed certain fouling release property.

  14. Detection of an amphiphilic biosample in a paper microchannel based on length.

    Science.gov (United States)

    Chen, Yu-Tzu; Yang, Jing-Tang

    2015-01-01

    We developed a simple method to achieve semiquantitative detection of an amphiphilic biosample through measuring the length of flow on a microfluidic analytical device (μPAD) based on paper. When an amphiphilic sample was dripped into a straight microchannel defined with a printed wax barrier (hydrophobic) on filter paper (hydrophilic), the length of flow was affected by the reciprocal effect between the sample, the filter-paper channel and the wax barrier. The flow length decreased with increasing concentration of an amphiphilic sample because of adsorption of the sample on the hydrophobic barrier. Measurement of the flow length enabled a determination of the concentration of the amphiphilic sample. The several tested samples included surfactants (Tween 20 and Triton X-100), oligonucleotides (DNA), bovine serum albumin (BSA), human albumin, nitrite, glucose and low-density lipoprotein (LDL). The results show that the measurement of the flow length determined directly the concentration of an amphiphilic sample, whereas a non-amphiphilic sample was not amenable to this method. The proposed method features the advantages of small cost, simplicity, convenience, directness, rapidity (<5 min) and requirement of only a small volume (5 μL) of sample, with prospective applications in developing areas and sites near patients for testing at a point of care (POCT).

  15. 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.

  16. Model Amphiphilic Block Copolymers with Tailored Molecular Weight and Composition in PDMS-Based Films to Limit Soft Biofouling

    Energy Technology Data Exchange (ETDEWEB)

    Wenning, Brandon M. [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa 56124, Italy; Martinelli, Elisa [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa 56124, Italy; Mieszkin, Sophie [School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 5TT, U.K.; Finlay, John A. [School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 5TT, U.K.; Fischer, Daniel [National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States; Callow, James A. [School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 5TT, U.K.; Callow, Maureen E. [School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 5TT, U.K.; Leonardi, Amanda K.; Ober, Christopher K.; Galli, Giancarlo [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa 56124, Italy

    2017-05-02

    A set of controlled surface composition films was produced utilizing amphiphilic block copolymers dispersed in a cross-linked poly(dimethylsiloxane) network. These block copolymers contained oligo(ethylene glycol) (PEGMA) and fluoroalkyl (AF6) side chains in selected ratios and molecular weights to control surface chemistry including antifouling and fouling-release performance. Such properties were assessed by carrying out assays using two algae, the green macroalga Ulva linza (favors attachment to polar surfaces) and the unicellular diatom Navicula incerta (favors attachment to nonpolar surfaces). All films performed well against U. linza and exhibited high removal of attached sporelings (young plants) under an applied shear stress, with the lower molecular weight block copolymers being the best performing in the set. The composition ratios from 50:50 to 60:40 of the AF6/PEGMA side groups were shown to be more effective, with several films exhibiting spontaneous removal of the sporelings. The cells of N. incerta were also removed from several coating compositions. All films were characterized by surface techniques including captive bubble contact angle, atomic force microscopy, and near edge X-ray absorption fine structure spectroscopy to correlate surface chemistry and morphology with biological performance.

  17. 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.

  18. 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.

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

    KAUST Repository

    Tong, Jing; Luxenhofer, Robert; Yi, Xiang; Jordan, Rainer; Kabanov, Alexander V.

    2010-01-01

    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. Reversible aggregation of lysozyme in a biodegradable amphiphilic multiblock copolymer.

    Science.gov (United States)

    van de Weert, Marco; van Dijkhuizen-Radersma, Riemke; Bezemer, Jeroen M; Hennink, Wim E; Crommelin, Daan J A

    2002-07-01

    Lysozyme-loaded poly(ethylene glycol terephthalate)-poly(butylene terephthalate) (PEGT/PBT) films were prepared using a water-in-oil emulsification solvent evaporation method. Infrared spectroscopic analysis of the dried films indicated the presence of non-covalent lysozyme aggregates in the polymer matrix. The use of methanol to enhance the drying rate of the films increased the relative amount of aggregates. Surprisingly, quantitative in-vitro release of fully active, non-aggregated lysozyme was observed, indicating that lysozyme forms reversible aggregates during encapsulation in PEGT/PBT films.

  1. Parameters influencing the introduction of plasmid DNA into cells by the use of synthetic amphiphiles as a carrier system

    OpenAIRE

    van der Woude, Irene; Willy Visser, H.; ter Beest, Martin B.A.; Wagenaar, Anno; Ruiters, Marcel H.J.; Engberts, Jan B.F.N.; Hoekstra, Dick

    1995-01-01

    Parameters that affect cellular transfection as accomplished by introducing DNA via carriers composed of cationic synthetic amphiphiles, have been investigated with the aim to obtain insight into the mechanism of DNA translocation. Such insight may be exploited in optimizing carrier properties of synthetic amphiphiles for molecules other than nucleic acids. In the present work, the interaction of vesicles composed of the cationic amphiphile dioleyloxy-propyl-trimethylammonium chloride (DOTMA)...

  2. Synthesis and Characterization of Cleavable Core-Cross-Linked Micelles Based on Amphiphilic Block Copolypeptoids as Smart Drug Carriers.

    Science.gov (United States)

    Li, Ang; Zhang, Donghui

    2016-03-14

    Amphiphilic block copolypeptoids consisting of a hydrophilic poly(N-ethyl glycine) segment and a hydrophobic poly[(N-propargyl glycine)-r-(N-decyl glycine)] random copolymer segment [PNEG-b-P(NPgG-r-NDG), EPgD] have been synthesized by sequential primary amine-initiated ring-opening polymerization (ROP) of the corresponding N-alkyl N-carboxyanhydride monomers. The block copolypeptoids form micelles in water and the micellar core can be cross-linked with a disulfide-containing diazide cross-linker by copper-mediated alkyne-azide cycloaddition (CuAAC) in aqueous solution. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis revealed the formation of spherical micelles with uniform size for both the core-cross-linked micelles (CCLMs) and non-cross-linked micelles (NCLMs) precursors for selective block copolypeptoid polymers. The CCLMs exhibited increased dimensional stability relative to the NCLMs in DMF, a nonselective solvent for the core and corona segments. Micellar dissociation of CCLMs can be induced upon addition of a reducing agent (e.g., dithiothreitol) in dilute aqueous solutions, as verified by a combination of fluorescence spectroscopy, size exclusion chromatography (SEC), and (1)H NMR spectroscopic measurement. Doxorubicin (DOX), an anticancer drug, can be loaded into the hydrophobic core of CCLMs with a maximal 23% drug loading capacity (DLC) and 37% drug loading efficiency (DLE). In vitro DOX release from the CCLMs can be triggered by DTT (10 mM), in contrast to significantly reduced DOX release in the absence of DTT, attesting to the reductively responsive characteristic of the CCLMs. While the CCLMs exhibited minimal cytotoxicity toward HepG2 cancer cells, DOX-loaded CCLMs inhibited the proliferation of the HepG2 cancer cells in a concentration and time dependent manner, suggesting the controlled release of DOX from the DOX-loaded CCLMS in the cellular environment.

  3. 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.

  4. Functional polymeric materials : Complexing amphiphiles as structure-inducing elements

    NARCIS (Netherlands)

    ten Brinke, G.; Ikkala, O.

    2003-01-01

    Self-assembly of polymeric comb-shaped supramolecules is a powerful tool to prepare functional materials. Enhanced conductivity due to hexagonal self-organization of conducting polyaniline and polarized photoluminance in solid-state films of rodlike poly(2,5-pyridinediyl) obtained by removing

  5. Amphiphile-induced heart muscle-cell (myocyte) injury: effects of intracellular fatty acid overload.

    Science.gov (United States)

    Janero, D R; Burghardt, C; Feldman, D

    1988-10-01

    Lipid amphiphile toxicity may be an important contributor to myocardial injury, especially during ischemia/reperfusion. In order to investigate directly the potential biochemical and metabolic effects of amphiphile overload on the functioning heart muscle cell (myocyte), a novel model of nonesterified fatty acid (NEFA)-induced myocyte damage has been defined. The model uses intact, beating neonatal rat myocytes in primary monolayer culture as a study object and 5-(tetradecyloxy)-2-furoic acid (TOFA) as a nonmetabolizable fatty acid. Myocytes incubated with TOFA accumulated it as NEFA, and the consequent NEFA amphiphile overload elicited a variety of cellular defects (including decreased beating rate, depletion of high-energy stores and glycogen pools, and breakdown of myocyte membrane phospholipid) and culminated in cell death. The amphiphile-induced cellular pathology could be reversed by removing TOFA from the culture medium, which resulted in intracellular TOFA "wash-out." Although the development and severity of amphiphile-induced myocyte injury could be correlated with both the intracellular TOFA/NEFA content (i.e., the level of TOFA to which the cells were exposed) and the duration of this exposure, removal of amphiphile overload did not inevitably lead to myocyte recovery. TOFA had adverse effects on myocyte mitochondrial function in situ (decoupling of oxidative phosphorylation, impairing respiratory control) and on myocyte oxidative catabolism (transiently increasing fatty acid beta oxidation, citric acid cycle flux, and glucose oxidation). The amphiphile-induced bioenergetic abnormalities appeared to constitute a state of "metabolic anoxia" underlying the progression of myocyte injury to cell death. This anoxic state could be ameliorated to some extent, but not prevented, by carbohydrate catabolism.

  6. Crystal morphology modification by the addition of tailor-made stereocontrolled poly(N-isopropyl acrylamide)

    DEFF Research Database (Denmark)

    Munk, Tommy; Baldursdottir, Stefania; Hietala, Sami

    2012-01-01

    . One such additive is the thermosensitive polymer poly(N-isopropyl acrylamide) (PNIPAM). The use of PNIPAM as a crystallization additive provides a possibility to affect viscosity at separation temperatures and nucleation and growth rates at higher temperatures. In this study, novel PNIPAM derivatives......; the morphology of crystals changed from needle to dendritic shape. Additionally, the amphiphilic nature of PNIPAM increased the solubility of nitrofurantoin in water. PNIPAMs with varying molecular weights and stereoregularities resulted in similar changes in the crystal habit of the drug regardless of whether...

  7. 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.

  8. Supramolecular ribbons from amphiphilic trisamides self-assembly.

    Science.gov (United States)

    García, Fátima; Buendía, Julia; Sánchez, Luis

    2011-08-05

    Two amphiphilic C(3)-symmetric OPE-based trisamides have been synthesized and their self-assembling features investigated in solution and on surface. Variable-temperature UV-vis experiments demonstrate the cooperative supramolecular polymerization of these trisamides that self-assemble by the operation of triple C═O···H-N H-bonding arrays between the amide functional groups and π-π stacking between the aromatic units. The helical organization of the aggregates has been demonstrated by circular dichroism at a concentration as low as 1 × 10(-4) M in acetonitrile. In the reported trisamides, the large hydrophobic aromatic core acts as a solvophobic module impeding the interaction between the polar TEG chains and the amide H-bonds. This strategy makes unnecessary the separation of the amide functional groups to the polar tri(ethylene glycol) chains by paraffinic fragments. Achiral trisamide 1 self-assembles into flat ribbon-like structures that experience an amplification of chirality by the addition of a small amount of chiral 2 that generates twisted stripes.

  9. Tailorable Exciton Transport in Doped Peptide–Amphiphile Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, Lee A. [Center; Sykes, Matthew E. [Center; Wu, Yimin A. [Center; Schaller, Richard D. [Center; Department; Wiederrecht, Gary P. [Center; Fry, H. Christopher [Center

    2017-08-29

    Light-harvesting biomaterials are an attractive target in photovoltaics, photocatalysis, and artificial photosynthesis. Through peptide self-assembly, complex nanostructures can be engineered to study the role of chromophore organization during light absorption and energy transport. To this end, we demonstrate the one-dimensional transport of excitons along naturally occurring, light-harvesting, Zn-protoporphyrin IX chromophores within self-assembled peptide-amphiphile nanofibers. The internal structure of the nanofibers induces packing of the porphyrins into linear chains. We find that this peptide assembly can enable long-range exciton diffusion, yet it also induces the formation of excimers between adjacent molecules, which serve as exciton traps. Electronic coupling between neighboring porphyrin molecules is confirmed by various spectroscopic methods. The exciton diffusion process is then probed through transient photoluminescence and absorption measurements and fit to a model for one-dimensional hopping. Because excimer formation impedes exciton hopping, increasing the interchromophore spacing allows for improved diffusivity, which we control through porphyrin doping levels. We show that diffusion lengths of over 60 nm are possible at low porphyrin doping, representing an order of magnitude improvement over the highest doping fractions.

  10. Vaccine Adjuvant Incorporation Strategy Dictates Peptide Amphiphile Micelle Immunostimulatory Capacity.

    Science.gov (United States)

    Zhang, Rui; Kramer, Jake S; Smith, Josiah D; Allen, Brittany N; Leeper, Caitlin N; Li, Xiaolei; Morton, Logan D; Gallazzi, Fabio; Ulery, Bret D

    2018-06-01

    Current vaccine research has shifted from traditional vaccines (i.e., whole-killed or live-attenuated) to subunit vaccines (i.e., protein, peptide, or DNA) as the latter is much safer due to delivering only the bioactive components necessary to produce a desirable immune response. Unfortunately, subunit vaccines are very weak immunogens requiring delivery vehicles and the addition of immunostimulatory molecules termed adjuvants to convey protective immunity. An interesting type of delivery vehicle is peptide amphiphile micelles (PAMs), unique biomaterials where the vaccine is part of the nanomaterial itself. Due to the modularity of PAMs, they can be readily modified to deliver both vaccine antigens and adjuvants within a singular construct. Through the co-delivery of a model antigenic epitope (Ovalbumin 319-340 -OVA BT ) and a known molecular adjuvant (e.g., 2,3-dipalmitoyl-S-glyceryl cysteine-Pam 2 C), greater insight into the mechanisms by which PAMs can exert immunostimulatory effects was gained. It was found that specific combinations of antigen and adjuvant can significantly alter vaccine immunogenicity both in vitro and in vivo. These results inform fundamental design rules that can be leveraged to fabricate optimal PAM-based vaccine formulations for future disease-specific applications. Graphical Abstract.

  11. Inhibition of cardiac inward rectifier currents by cationic amphiphilic drugs.

    Science.gov (United States)

    van der Heyden, M A G; Stary-Weinzinger, A; Sanchez-Chapula, J A

    2013-09-01

    Cardiac inward rectifier channels belong to three different classes of the KIR channel protein family. The KIR2.x proteins generate the classical inward rectifier current, IK1, while KIR3 and KIR6 members are responsible for the acetylcholine responsive and ATP sensitive inward rectifier currents IKAch and IKATP, respectively. Aberrant function of these channels has been correlated with severe cardiac arrhythmias, indicating their significant contribution to normal cardiac electrophysiology. A common feature of inward rectifier channels is their dependence on the lipid phosphatidyl-4,5-bisphospate (PIP2) interaction for functional activity. Cationic amphiphilic drugs (CADs) are one of the largest classes of pharmaceutical compounds. Several widely used CADs have been associated with inward rectifier current disturbances, and recent evidence points to interference of the channel-PIP2 interaction as the underlying mechanism of action. Here, we will review how six of these well known drugs, used for treatment in various different conditions, interfere in cardiac inward rectifier functioning. In contrast, KIR channel inhibition by the anionic anesthetic thiopental is achieved by a different mechanism of channel-PIP2 interference. We will discuss the latest basic science insights of functional inward rectifier current characteristics, recently derived KIR channel structures and specific PIP2-receptor interactions at the molecular level and provide insight in how these drugs interfere in the structure-function relationships.

  12. 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.

  13. Conductivity hysteresis in polymer electrolytes incorporating poly(tetrahydrofuran)

    Energy Technology Data Exchange (ETDEWEB)

    Akbulut, Ozge; Taniguchi, Ikuo; Mayes, Anne M. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States); Kumar, Sundeep; Shao-Horn, Yang [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States)

    2007-01-01

    Conductivity hysteresis and room temperature ionic conductivities >10{sup -3}S/cm were recently reported for electrolytes prepared from blends of an amphiphilic comb copolymer, poly[2,5,8,11,14-pentaoxapentadecamethylene (5-hexadecyloxy-1,3-phenylene)] (polymer I), and a linear multiblock copolymer, poly(oligotetrahydrofuran-co-dodecamethylene) (polymer II), following thermal treatment [F. Chia, Y. Zheng, J. Liu, N. Reeves, G. Ungar, P.V. Wright, Electrochim. Acta 43 (2003) 1939]. To investigate the origin of these effects, polymers I and II were synthesized in this work, and the conductivity and thermal properties of the individual polymers were investigated. AC impedance measurements were conducted on I and II doped with LiBF{sub 4} or LiClO{sub 4} during gradual heating to 110{sup o}C and slow cooling to room temperature. Significant conductivity hysteresis was seen for polymer II, and was similarly observed for poly(tetrahydrofuran) (PTHF) homopolymer at equivalent doping levels. From thermogravimetric analysis (TGA), gel permeation chromatography (GPC) and {sup 1}H NMR spectroscopy, both polymer II and PTHF were found to partially decompose to THF during heat treatment, resulting in a self-plasticizing effect on conductivity. (author)

  14. Phases and phase transition in insoluble and adsorbed monolayers of amide amphiphiles: Specific characteristics of the condensed phases.

    Science.gov (United States)

    Vollhardt, D

    2015-08-01

    For understanding the role of amide containing amphiphiles in inherently complex biological processes, monolayers at the air-water interface are used as simple biomimetic model systems. The specific characteristics of the condensed phases and phase transition in insoluble and adsorbed monolayers of amide amphiphiles are surveyed to highlight the effect of the chemical structure of the amide amphiphiles on the interfacial interactions in model monolayers. The mesoscopic topography and/or two-dimensional lattice structures of selected amino acid amphiphiles, amphiphilic N-alkylaldonamide, amide amphiphiles with specific tailored headgroups, such as amide amphiphiles based on derivatized ethanolamine, e.g. acylethanolamines (NAEs) and N-,O-diacylethanolamines (DAEs) are presented. Special attention is devoted the dominance of N,O-diacylated ethanolamine in mixed amphiphilic acid amide monolayers. The evidence that a first order phase transition can occur in adsorption layers and that condensed phase domains of mesoscopic scale can be formed in adsorption layers was first obtained on the basis of the experimental characteristics of a tailored amide amphiphile. New thermodynamic and kinetic concepts for the theoretical description of the characteristics of amide amphiphile's monolayers were developed. In particular, the equation of state for Langmuir monolayers generalized for the case that one, two or more phase transitions occur, and the new theory for phase transition in adsorbed monolayers are experimentally confirmed at first by amide amphiphile monolayers. Despite the significant progress made towards the understanding the model systems, these model studies are still limited to transfer the gained knowledge to biological systems where the fundamental physical principles are operative in the same way. The study of biomimetic systems, as described in this review, is only a first step in this direction. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Lyotropic liquid crystalline phase behaviour in amphiphile-protic ionic liquid systems.

    Science.gov (United States)

    Chen, Zhengfei; Greaves, Tamar L; Fong, Celesta; Caruso, Rachel A; Drummond, Calum J

    2012-03-21

    Approximate partial phase diagrams for nine amphiphile-protic ionic liquid (PIL) systems have been determined by synchrotron source small angle X-ray scattering, differential scanning calorimetry and cross polarised optical microscopy. The binary phase diagrams of some common cationic (hexadecyltrimethyl ammonium chloride, CTAC, and hexadecylpyridinium bromide, HDPB) and nonionic (polyoxyethylene (10) oleyl ether, Brij 97, and Pluronic block copolymer, P123) amphiphiles with the PILs, ethylammonium nitrate (EAN), ethanolammonium nitrate (EOAN) and diethanolammonium formate (DEOAF), have been studied. The phase diagrams were constructed for concentrations from 10 wt% to 80 wt% amphiphile, in the temperature range 25 °C to >100 °C. Lyotropic liquid crystalline phases (hexagonal, cubic and lamellar) were formed at high surfactant concentrations (typically >50 wt%), whereas at thermal stability of the phases formed by these surfactants persisted to temperatures above 100 °C. The phase behaviour of amphiphile-PIL systems was interpreted by considering the PIL cohesive energy, liquid nanoscale order, polarity and ionicity. For comparison the phase behaviour of the four amphiphiles was also studied in water.

  16. Fabrication of novel biodegradable porous bone scaffolds based on amphiphilic hydroxyapatite nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Xiaoyan; Hui, Junfeng [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an 710069, Shaanxi, PR China2 (China); Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry & Materials Science, Northwest University, Xi' an 710069, Shaanxi (China); Li, Hui; Zhu, Chenhui [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an 710069, Shaanxi, PR China2 (China); Hua, Xiufu, E-mail: hua_xiufu@163.com [Department of Scientific Research and Development, Tsinghua University, Beijing 100084 (China); Ma, Haixia, E-mail: mahx@nwu.edu.cn [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry & Materials Science, Northwest University, Xi' an 710069, Shaanxi (China); Fan, Daidi, E-mail: fandaidi@nwu.edu.cn [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an 710069, Shaanxi, PR China2 (China)

    2017-06-01

    This paper describes a new synthetic strategy and biological application for novel amphiphilic hydroxyapatite (HAp) nanorods. The prepared HAp nanorods were able to be dispersed in water, ethyl alcohol and cyclohexane. The co-anchoring of the multidentate ligands of PEG 20000 and hydrophobic oleic acid (OA) on the rods' surfaces endowed them with excellent amphibious properties. Utilizing amphiphilic HAp nanorods with excellent biocompatibility as the inorganic phase, human-like collagen (HLC) as the organic phase and natural genipin as the cross-linker, optimal HLC/HAp porous scaffolds (HLC: HAp = 1:4, w/w) were fabricated. The compression stress and three-point bending strength of the scaffolds with pore diameters of 150 to 200 μm reached approximately 3.4 MPa and 5.4 MPa, respectively, and their porosity was 77.35 ± 3.75%. Cytological tests showed that HLC/HAp scaffolds could contribute to cell proliferation and differentiation. The results indicated that these novel amphiphilic HAp nanorods can be expected to become recognized as an excellent inorganic material for the porous scaffolds used in repairing bone and related applications. - Highlights: • A simple and effective hydrothermal method was developed for preparing uniform HAp nanorods with amphiphilic surfaces. • The synthesized amphiphilic HAp nanorods could be dispersed in water, ethyl alcohol or cyclohexane. • The prepared HLC/HAp porous scaffolds had good mechanical properties, biocompatibility and osteoconductive etc.

  17. Fabrication of novel biodegradable porous bone scaffolds based on amphiphilic hydroxyapatite nanorods

    International Nuclear Information System (INIS)

    Zheng, Xiaoyan; Hui, Junfeng; Li, Hui; Zhu, Chenhui; Hua, Xiufu; Ma, Haixia; Fan, Daidi

    2017-01-01

    This paper describes a new synthetic strategy and biological application for novel amphiphilic hydroxyapatite (HAp) nanorods. The prepared HAp nanorods were able to be dispersed in water, ethyl alcohol and cyclohexane. The co-anchoring of the multidentate ligands of PEG 20000 and hydrophobic oleic acid (OA) on the rods' surfaces endowed them with excellent amphibious properties. Utilizing amphiphilic HAp nanorods with excellent biocompatibility as the inorganic phase, human-like collagen (HLC) as the organic phase and natural genipin as the cross-linker, optimal HLC/HAp porous scaffolds (HLC: HAp = 1:4, w/w) were fabricated. The compression stress and three-point bending strength of the scaffolds with pore diameters of 150 to 200 μm reached approximately 3.4 MPa and 5.4 MPa, respectively, and their porosity was 77.35 ± 3.75%. Cytological tests showed that HLC/HAp scaffolds could contribute to cell proliferation and differentiation. The results indicated that these novel amphiphilic HAp nanorods can be expected to become recognized as an excellent inorganic material for the porous scaffolds used in repairing bone and related applications. - Highlights: • A simple and effective hydrothermal method was developed for preparing uniform HAp nanorods with amphiphilic surfaces. • The synthesized amphiphilic HAp nanorods could be dispersed in water, ethyl alcohol or cyclohexane. • The prepared HLC/HAp porous scaffolds had good mechanical properties, biocompatibility and osteoconductive etc.

  18. Controllable Self-Assembly of Amphiphilic Zwitterionic PBI Towards Tunable Surface Wettability of the Nanostructures.

    Science.gov (United States)

    Ye, Yong; Lü, Baozhong; Cheng, Wenyu; Wu, Zhen; Wei, Jie; Yin, Meizhen

    2017-05-04

    Amphiphilic molecules have received wide attention as they possess both hydrophobic and hydrophilic properties, and can form diverse nanostructures in selective solvents. Herein, we report an asymmetric amphiphilic zwitterionic perylene bisimide (AZP) with an octyl chain and a zwitterionic group on the opposite imide positions of perylene tetracarboxylic dianhydride. The controllable nanostructures of AZP with tunable hydrophilic/hydrophobic surface have been investigated through solvent-dependent amphiphilic self-assembly as confirmed by SEM, TEM, and contact angle measurements. The planar perylene core of AZP contributes to strong π-π stacking, while the amphiphilic balance of asymmetric AZP adjusts the self-assembly property. Additionally, due to intermolecular π-π stacking and solvent-solute interactions, AZP could self-assemble into hydrophilic microtubes in a polar solvent (acetone) and hydrophobic nanofibers in an apolar solvent (hexane). This facile method provides a new pathway for controlling the surface properties based on an asymmetric amphiphilic zwitterionic perylene bisimide. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

    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

    International Nuclear Information System (INIS)

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

    2009-01-01

    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. Self-Assembly of Amphiphilic Block Copolypeptoids with C 2 -C 5 Side Chains in Aqueous Solution

    KAUST Repository

    Fetsch, Corinna; Flecks, Silvana; Gieseler, Dan; Marschelke, Claudia; Ulbricht, Juliane; van Pé e, Karl-Heinz; Luxenhofer, Robert

    2014-01-01

    © 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

  2. 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

  3. Morphological changes of monolayers of two polymerizable pyridine amphiphiles upon complexation with Cu(II) ions at the air-water interface

    NARCIS (Netherlands)

    Werkman, P.J.; Schouten, A.J.; Noordegraaf, M.A.; Kimkes, P.; Sudhölter, E.J.R.

    1998-01-01

    The monolayer behavior of two amphiphilic, diacetylenic units containing pyridine Ligands at the air-water interface is studied by measuring the surface pressure-area isotherms and by Brewster angle microscopy(BAM). Both amphiphiles form stable monolayers at the air-water interface. The amphiphile

  4. 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.

  5. Amphiphilic phase-transforming catalysts for transesterification of triglycerides

    Science.gov (United States)

    Nawaratna, Gayan Ivantha

    Heterogeneous catalytic reactions that involve immiscible liquid-phase reactants are challenging to conduct due to limitations associated with mass transport. Nevertheless, there are numerous reactions such as esterification, transesterification, etherification, and hydrolysis where two immiscible liquid reactants (such as polar and non-polar liquids) need to be brought into contact with a catalyst. With the intention of alleviating mass transport issues associated with such systems but affording the ability to separate the catalyst once the reaction is complete, the overall goal of this study is geared toward developing a catalyst that has emulsification properties as well as the ability to phase-transfer (from liquid-phase to solid-phase) while the reaction is ongoing and evaluating the effectiveness of such a catalytic process in a practical reaction. To elucidate this concept, the transesterification reaction was selected. Metal-alkoxides that possess acidic and basic properties (to catalyze the reaction), amphiphilic properties (to stabilize the alcohol/oil emulsion) and that can undergo condensation polymerization when heated (to separate as a solid subsequent to the completion of the reaction) were used to test the concept. Studies included elucidating the effect of metal sites and alkoxide sites and their concentration effects on transesterification reaction, effect of various metal alkoxide groups on the phase stability of the reactant system, and kinetic effects of the reaction system. The studies revealed that several transition-metal alkoxides, especially, titanium and yttrium based, responded positively to this reaction system. These alkoxides were able to be added to the reaction medium in liquid phase and were able to stabilize the alcohol/oil system. The alkoxides were selective to the transesterification reaction giving a range of ester yields (depending on the catalyst used). It was also observed that transition-metal alkoxides were able to be

  6. Biophysical mechanisms of endotoxin neutralization by cationic amphiphilic peptides.

    Science.gov (United States)

    Kaconis, Yani; Kowalski, Ina; Howe, Jörg; Brauser, Annemarie; Richter, Walter; Razquin-Olazarán, Iosu; Iñigo-Pestaña, Melania; Garidel, Patrick; Rössle, Manfred; Martinez de Tejada, Guillermo; Gutsmann, Thomas; Brandenburg, Klaus

    2011-06-08

    Bacterial endotoxins (lipopolysaccharides (LPS)) are strong elicitors of the human immune system by interacting with serum and membrane proteins such as lipopolysaccharide-binding protein (LBP) and CD14 with high specificity. At LPS concentrations as low as 0.3 ng/ml, such interactions may lead to severe pathophysiological effects, including sepsis and septic shock. One approach to inhibit an uncontrolled inflammatory reaction is the use of appropriate polycationic and amphiphilic antimicrobial peptides, here called synthetic anti-LPS peptides (SALPs). We designed various SALP structures and investigated their ability to inhibit LPS-induced cytokine secretion in vitro, their protective effect in a mouse model of sepsis, and their cytotoxicity in physiological human cells. Using a variety of biophysical techniques, we investigated selected SALPs with considerable differences in their biological responses to characterize and understand the mechanism of LPS inactivation by SALPs. Our investigations show that neutralization of LPS by peptides is associated with a fluidization of the LPS acyl chains, a strong exothermic Coulomb interaction between the two compounds, and a drastic change of the LPS aggregate type from cubic into multilamellar, with an increase in the aggregate sizes, inhibiting the binding of LBP and other mammalian proteins to the endotoxin. At the same time, peptide binding to phospholipids of human origin (e.g., phosphatidylcholine) does not cause essential structural changes, such as changes in membrane fluidity and bilayer structure. The absence of cytotoxicity is explained by the high specificity of the interaction of the peptides with LPS. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  7. Maltose-neopentyl glycol (MNG) amphiphiles for solubilization, stabilization and crystallization of membrane proteins.

    Science.gov (United States)

    Chae, Pil Seok; Rasmussen, Søren G F; Rana, Rohini R; Gotfryd, Kamil; Chandra, Richa; Goren, Michael A; Kruse, Andrew C; Nurva, Shailika; Loland, Claus J; Pierre, Yves; Drew, David; Popot, Jean-Luc; Picot, Daniel; Fox, Brian G; Guan, Lan; Gether, Ulrik; Byrne, Bernadette; Kobilka, Brian; Gellman, Samuel H

    2010-12-01

    The understanding of integral membrane protein (IMP) structure and function is hampered by the difficulty of handling these proteins. Aqueous solubilization, necessary for many types of biophysical analysis, generally requires a detergent to shield the large lipophilic surfaces of native IMPs. Many proteins remain difficult to study owing to a lack of suitable detergents. We introduce a class of amphiphiles, each built around a central quaternary carbon atom derived from neopentyl glycol, with hydrophilic groups derived from maltose. Representatives of this maltose-neopentyl glycol (MNG) amphiphile family show favorable behavior relative to conventional detergents, as manifested in multiple membrane protein systems, leading to enhanced structural stability and successful crystallization. MNG amphiphiles are promising tools for membrane protein science because of the ease with which they may be prepared and the facility with which their structures may be varied.

  8. Synthesis and characterization of maltose-based amphiphiles as supramolecular hydrogelators.

    Science.gov (United States)

    Clemente, María J; Fitremann, Juliette; Mauzac, Monique; Serrano, José L; Oriol, Luis

    2011-12-20

    Low molecular mass amphiphilic glycolipids have been prepared by linking a maltose polar head and a hydrophobic linear chain either by amidation or copper(I)-catalyzed azide-alkyne [3 + 2] cycloaddition. The liquid crystalline properties of these amphiphilic materials have been characterized. The influence of the chemical structure of these glycolipids on the gelation properties in water has also been studied. Glycolipids obtained by the click coupling of the two components give rise to stable hydrogels at room temperature. The fibrillar structure of supramolecular hydrogels obtained by the self-assembly of these gelators have been characterized by electron microscopy. Fibers showed some torsion, which could be related with a chiral supramolecular arrangement of amphiphiles, as confirmed by circular dichroism (CD). The sol-gel transition temperature was also determined by differential scanning calorimetry (DSC) and NMR. © 2011 American Chemical Society

  9. Effect of ionizing radiation exposure in the morphology of modified HDPE with amphiphilic particles

    International Nuclear Information System (INIS)

    Saldanha, Ana Luiza M.; Vivas, Viviane; Zylberberg, Marcel P.; Silva, Tamara I.; Cardoso, Andre Luis V.; Pereira, Iaci M.; Patricio, Patricia S.O.

    2015-01-01

    One of the techniques used to improve the properties of high performance polymers is the addition of hybrid particles in the polymer. In this context, amphiphilic particles were synthesized in order to provide surface characteristics that enhance the interaction of the interface with the polymeric matrix of high density polyethylene (HDPE). The amphiphilic particles were added to matrix of HDPE and the modified polymer composites were exposed to ionizing radiation (x-rays) for different times. The changes caused by exposure to ionizing radiation in the composite morphology was observed through the small angle x-ray technique. The results suggest that the addition of amphiphilic particles increased the stability of the composite to degradation by radiation. (author)

  10. Poly(furfuryl alcohol)

    Indian Academy of Sciences (India)

    This paper describes a facile hydrothermal approach to the large-scale synthesis of well-dispersed poly(furfuryl alcohol) (PFA) nanospheres with an average diameter of 350 nm in the presence of poly(vinyl pyrrolidone) (PVP). Scanning electron microscopy and transmission electron microscopy studies showed that ...

  11. Self-assembly of a triangle-shaped, hexaplatinum-incorporated, supramolecular amphiphile in solution and at interfaces.

    Science.gov (United States)

    Maran, Umamageswaran; Britt, David; Fox, Christopher B; Harris, Joel M; Orendt, Anita M; Conley, Hiram; Davis, Robert; Hlady, Vladamir; Stang, Peter J

    2009-08-24

    The self-assembly and characterization of a novel supramolecular amphiphile built from a new 60 degree amphiphilic precursor that incorporates hydrophilic platinum(II) metals and hydrophobic dioctadecyloxy chains is reported. The amphiphilic macrocycle and its precursor compound have been characterized by multinuclear NMR spectroscopy, ESI-MS, and other standard techniques. The coacervate morphology of the amphiphile at the liquid-liquid interface has been studied by using confocal optical microscopy and in situ Raman spectroscopy. The self-assembly of the amphiphilic macrocycle at the air-water interface has been investigated through Langmuir-trough techniques. The study indicates the possible formation of surface micelle-like aggregates. The disparity between the experimental molecular areas and those derived from molecular models support the idea of aggregation. AFM images of the surface aggregates show the formation of a flat topology with arbitrary ridgelike patterns. Reasonable molecular-packing arrangements are proposed to explain the molecular organization within the observed structures.

  12. Electrostatically Driven Assembly of Charged Amphiphiles Forming Crystallized Membranes, Vesicles and Nanofiber Arrays

    Science.gov (United States)

    Leung, Cheuk Yui Curtis

    Charged amphiphilic molecules can self-assemble into a large variety of objects including membranes, vesicles and fibers. These micro to nano-scale structures have been drawing increasing attention due to their broad applications, especially in biotechnology and biomedicine. In this dissertation, three self-assembled systems were investigated: +3/-1 self-assembled catanionic membranes, +2/-1 self-assembled catanionic membranes and +1 self-assembled nanofibers. Transmission electron microscopy (TEM) combined with synchrotron small and wide angle x-ray scattering (SAXS and WAXS) were used to characterize the coassembled structures from the mesoscopic to nanometer scale. We designed a system of +3 and -1 ionic amphiphiles that coassemble into crystalline ionic bilayer vesicles with large variety of geometries that resemble polyhedral cellular crystalline shells and archaea wall envelopes. The degree of ionization of the amphiphiles and their intermolecular electrostatic interactions can be controlled by varying pH. The molecular packing of these membranes showed a hexagonal to rectangular-C to hexagonal phase transition with increasing pH, resulting in significant changes to the membrane morphology. A similar mixture of +2 and -1 ionic amphiphiles was also investigated. In addition to varying pH, which controls the headgroup attractions, we also adjust the tail length of the amphiphiles to control the van der Waals interactions between the tails. A 2D phase diagram was developed to show how pH and tail length can be used to control the intermolecular packing within the membranes. Another system of self-assembled nanofiber network formed by positively charged amphiphiles was also studied. These highly charged fibers repel each other and are packed in hexagonal lattice with lattice constant at least eight times of the fiber diameter. The d-spacing and the crystal structure can be controlled by varying the solution concentration and temperature.

  13. 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.

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

    Science.gov (United States)

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

    2017-04-01

    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.

  15. Amphiphilic silicone architectures via anaerobic thiol-ene chemistry.

    Science.gov (United States)

    Keddie, Daniel J; Grande, John B; Gonzaga, Ferdinand; Brook, Michael A; Dargaville, Tim R

    2011-11-18

    Despite broad application, few silicone-based surfactants of known structure or, therefore, surfactancy have been prepared because of an absence of selective routes and instability of silicones to acid and base. Herein the synthesis of a library of explicit silicone-poly(ethylene glycol) (PEG) materials is reported. Pure silicone fragments were generated by the B(C(6)F(5))(3)-catalyzed condensation of alkoxysilanes and vinyl-functionalized hydrosilanes. The resulting pure products were coupled to thiol-terminated PEG materials using photogenerated radicals under anaerobic conditions.

  16. Charge-Transfer Supra-Amphiphiles Built by Water-Soluble Tetrathiafulvalenes and Viologen-Containing Amphiphiles: Supramolecular Nanoassemblies with Modifiable Dimensions.

    Science.gov (United States)

    Lv, Zhong-Peng; Chen, Bin; Wang, Hai-Ying; Wu, Yue; Zuo, Jing-Lin

    2015-08-05

    In this study, multidimensional nanoassemblies with various morphologies such as nanosheets, nanorods, and nanofibers are developed via charge-transfer interaction and supra-amphiphile self-assembling in aqueous phase. The charge-transfer interactions between tetrathiafulvalene derivatives (TTFs) and methyl viologen derivatives (MVs) have been confirmed by the characteristic charger-transfer absorption. (1) H NMR and electrospray ionizsation mass spectrometry (ESI-MS) analyses also indicate supra-amphiphiles are formed by the combination of TTFs and MVs head group through charge-transfer interaction and Coulombic force. X-ray single crystal structural studies, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) reveal that both linkage pattern of TTFs in hydrophilic part and alkane chain structure in hydrophobic part have significant influence on nanoassemblies morphology and microstructure. Moreover, gold nanoparticles (AuNPs) are introduced in the above supramolecular nanoassemblies to construct a supra-amphiphile-driven organic-AuNPs assembly system. AuNPs could be assembled into 1D-3D structures by adding different amount of MVs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. 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

  18. The characters of self-assembly core/shell nanoparticles of amphiphilic hyperbranched polyethers as drug carriers

    International Nuclear Information System (INIS)

    Ajun Wan; Yuxia, Kou

    2008-01-01

    The characters of self-assembly core/shell nanoparticles of amphiphilic hyperbranched polyethers (HP-g-PEO) as drug carriers were investigated. The HP-g-PEO consisting of hydrophobic HP-g-PEO core and hydrophilic poly(ethylene glycol) arms was prepared by the cation ring-opening polymerization. A series of HP-g-PEO samples with different degree of branching (DB) were synthesized under various reaction temperatures. Nanoparticles (NP) were obtained by self-assembly of HP-g-PEO in aqueous media. The structure of resulting HP-g-PEO was characterized by IR, 13 CNMR and GPC. Dynamic light scattering and transmission electron microscopy were applied to characterize the sizes and size distributions of NP. The results demonstrated that the mean diameters of NP were less than 100 nm, which exhibited uniform spherical formations and narrow size distributions. Using hydrophobic drug Probucol (PRO) as model drug, the particle sizes of drug loaded NP were larger than relative blank NP. The drug loading efficiency (LE) and incorporation efficiency (IE) of these NP were achieved to 35 and 89%, respectively. The in vitro release of PRO from the NP exhibited a sustained release and the cumulative drugs released for more than 600 h. The most important factor to affect drug release was the value of DB of HP-g-PEO. With the DB of HP-g-PEO increasing, the size and size distribution of NP decreased as well as the release rate. However, the small DB was beneficial to the LE of NP. Nanoparticle size and size distribution, LE, IE, and drug release rate were slightly affected by the initial solution concentration of polyethers. The co-incorporated hydrophilic drug had influence slightly on the release of drug from drug loaded NP. The results of in vitro drug release suggested that the core/shell NP performed good controlled release behaviors with potential practice as novelty drug delivery vehicles

  19. 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.

  20. Glucose-Neopentyl Glycol (GNG) Amphiphiles for Membrane Protein Solubilization, Stabilization and Crystallization

    Science.gov (United States)

    Rana, Rohini R.; Gotfryd, Kamil; Rasmussen, Søren G. F.; Kruse, Andrew C.; Cho, Kyung Ho; Capaldi, Stefano; Carlsson, Emil; Kobilka, Brian; Loland, Claus J.; Gether, Ulrik; Banerjee, Surajit

    2012-01-01

    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 al. PMID:23165475

  1. Glucose-Neopentyl Glycol (GNG) Amphiphiles for Membrane Protein Solubilization, Stabilization and Crystallization

    OpenAIRE

    Chae, Pil Seok; Rana, Rohini R.; Gotfryd, Kamil; Rasmussen, Søren G. F.; Kruse, Andrew C.; Cho, Kyung Ho; Capaldi, Stefano; Carlsson, Emil; Kobilka, Brian; Loland, Claus J.; Gether, Ulrik; Banerjee, Surajit; Byrne, Bernadette; Lee, John K.; Gellman, Samuel H.

    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 al.

  2. 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

    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

  3. Peptide amphiphile nanoparticles enhance the immune response against a CpG-adjuvanted influenza antigen

    NARCIS (Netherlands)

    Zope, H.; Quer, C.B.; Bomans, P.H.H.; Sommerdijk, N.A.J.M.; Kros, A.; Jiskoot, W.

    2014-01-01

    Cationic peptide amphiphile nanoparticles are employed for co-delivery of immune modulator CpG and antigen. This results in better targeting to the antigen presenting cells and eliciting strong Th1 response, which is effective against the intracellular pathogens.

  4. Anti-Biofouling Properties of Comblike Block Copolymers with Amphiphilic Side Chains

    International Nuclear Information System (INIS)

    Krishnan, S.; Ayothi, R.; Hexemer, A.; Finlay, J.; Sohn, K.; Perry, R.; Ober, C.; Kramer, E.; Callow, M.

    2006-01-01

    Surfaces of novel block copolymers with amphiphilic side chains were studied for their ability to influence the adhesion of marine organisms. The surface-active polymer, obtained by grafting fluorinated molecules with hydrophobic and hydrophilic blocks to a block copolymer precursor, showed interesting bioadhesion properties. Two different algal species, one of which adhered strongly to hydrophobic surfaces, and the other, to hydrophilic surfaces, showed notably weak adhesion to the amphiphilic surfaces. Both organisms are known to secrete adhesive macromolecules, with apparently different wetting characteristics, to attach to underwater surfaces. The ability of the amphiphilic surface to undergo an environment-dependent transformation in surface chemistry when in contact with the extracellular polymeric substances is a possible reason for its antifouling nature. Near-edge X-ray absorption fine structure spectroscopy (NEXAFS) was used, in a new approach based on angle-resolved X-ray photoelectron spectroscopy (XPS), to determine the variation in chemical composition within the top few nanometers of the surface and also to study the surface segregation of the amphiphilic block. A mathematical model to extract depth-profile information from the normalized NEXAFS partial electron yield is developed

  5. In situ SERS detection of emulsifiers at lipid interfaces using label-free amphiphilic gold nanoparticles.

    Science.gov (United States)

    Li, Yue; Driver, Michael; Winuprasith, Thunnalin; Zheng, Jinkai; McClements, David Julian; He, Lili

    2014-10-21

    Herein, we fabricated amphiphilic gold nanoparticles (GNPs) that can self-assemble at oil-water interfaces. We applied those GNPs for in situ SERS detection of emulsifier molecules within the interfacial region of oil in water (O/W) emulsion systems.

  6. Influence of corona structure on binding of an ionic surfactant in oppositely charged amphiphilic polyelectrolyte micelles

    Czech Academy of Sciences Publication Activity Database

    Delisavva, F.; Uchman, M.; Škvarla, J.; Wozniak, E.; Pavlova, Ewa; Šlouf, Miroslav; Garamus, V. M.; Procházka, K.; Štěpánek, M.

    2016-01-01

    Roč. 32, č. 16 (2016), s. 4059-4065 ISSN 0743-7463 R&D Projects: GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : amphiphilic polymers * polyelectrolyte * corona structure Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.833, year: 2016

  7. New carbon-carbon linked amphiphilic carboranyl-porphyrins as boron neutron capture agents

    International Nuclear Information System (INIS)

    Vicente, M.G.H.; Wickramasinghe, A.; Shetty, S.J.; Smith, K.M.

    2000-01-01

    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)

  8. New penta-saccharide-bearing tripod amphiphiles for membrane protein structure studies

    DEFF Research Database (Denmark)

    Ehsan, Muhammad; Ghani, Lubna; Du, Yang

    2017-01-01

    of detergents, are available, purification and structural characterization of many membrane proteins remain challenging. In the current study, a new class of tripod amphiphiles bearing two different penta-saccharide head groups, designated TPSs, were developed and evaluated for their ability to extract...

  9. Amphiphilic derivatives of (3β,17β)-3-hydroxyandrost-5-ene-17-carboxylic acid

    Czech Academy of Sciences Publication Activity Database

    Özdemir, Zülal; Bildziukevich, Uladzimir; Šaman, David; Havlíček, Libor; Rárová, L.; Navrátilová, L.; Wimmer, Zdeněk

    2017-01-01

    Roč. 128, DEC (2017), s. 58-67 ISSN 0039-128X R&D Projects: GA MŠk LD15012 Institutional support: RVO:61389030 ; RVO:61388963 Keywords : Amphiphile * Antimicrobial activity * Cytotoxicity * Diamine * Polyamine * Steroid Subject RIV: CC - Organic Chemistry; CC - Organic Chemistry (UOCHB-X) OBOR OECD: Organic chemistry Impact factor: 2.282, year: 2016

  10. Immunochemically identical hydrophilic and amphiphilic forms of the bovine adrenomedullary dopamine beta-hydroxylase

    DEFF Research Database (Denmark)

    Bjerrum, Ole Jannik; Helle, K B; Bock, Elisabeth Marianne

    1979-01-01

    . The dopamine beta-hydroxylases of the buffer and membrane fractions were antigenically identical, but differed in their amphiphilicity, as demonstrated by the change in precipitation patterns on removal of Triton X-100 from the gel, on charge-shift crossed immunoelectrophoresis and on crossed hydrophobic...

  11. 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.

  12. Fabrication of Propeller-Shaped Supra-amphiphile for Construction of Enzyme-Responsive Fluorescent Vesicles.

    Science.gov (United States)

    Li, Jie; Liu, Kaerdun; Han, Yuchun; Tang, Ben Zhong; Huang, Jianbin; Yan, Yun

    2016-10-04

    Propeller-shaped molecules have been recognized to display fantastic AIE (aggregation induced emission), but they can hardly self-assemble into nanostructures. Herein, we for the first time report that ionic complexation between a water-soluble tetrapheneyl derivative and an enzyme substrate in aqueous media produces a propeller-shaped supra-amphiphile that self-assembles into enzyme responsive fluorescent vesicles. The supra-amphiphile was fabricated upon complexation between a water-soluble propeller-shaped AIE luminogen TPE-BPA and myristoylcholine chloride (MChCl) in aqueous media. MChCl filled in the intramolecular voids of propeller-shaped TPE-BPA upon supra-amphiphile formation, which endows the supra-amphiphile superior self-assembling ability to the component molecules thus leading to the formation of fluorescent vesicles. Because MChCl is the substrate of cholinesterases, the vesicles dissemble in the presence of cholinesterases, and the fluorescent intensity can be correlated to the level of enzymes. The resulting fluorescent vesicles may be used to recognize the site of Alzheimer's disease, to encapsulate the enzyme inhibitor, and to release the inhibitor at the disease site.

  13. 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...

  14. Conformational properties of rigid-chain amphiphilic macromolecules : The phase diagram

    NARCIS (Netherlands)

    Markov, V. A.; Vasilevskaya, V. V.; Khalatur, P. G.; ten Brinke, G.; Khokhlov, A. R.

    The coil-globule transition in rigid-chain amphiphilic macromolecules was studied by means of computer simulation, and the phase diagrams for such molecules in the solvent quality-persistence length coordinates were constructed. It was shown that the type of phase diagram depends to a substantial

  15. 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.

  16. Raman study of magnesium induced conversion of polyU·polyA duplexes to polyU·polyA·polyU triplexes

    OpenAIRE

    Herrera, S. J. Espinoza; Štepánek, J.

    2010-01-01

    Raman titration experiment with magnesium salt added gradually to aqueous solution of duplexes formed by RNA homopolynucleotides polyU and polyA was performed to reveal its effect on homopolynucleotide complexes. Statistical analysis of obtained spectral set has confirmed the effect already found by less structurally sensitive methods [Nucleic Acids Res. 31(17) (2003), 5101–5107] that at sufficiently high concentrations magnesium causes transformation of polyU·polyA duplexes to polyU·polyA·po...

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

    International Nuclear Information System (INIS)

    Wu, W-T; Shi Lei; Pang Wenmin; Wang Yusong; Zhu Qingren; Xu Guoyong

    2006-01-01

    Novel spherical three-dimensional (3D) dendritic Bi 2 S 3 /cross-linked poly(vinyl alcohol) (PVA) nanocomposites were successfully synthesized in aqueous solution of amphiphilic polyvinylacetone (PVKA) (ketalization degree D H = 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

  18. Comb-like amphiphilic polypeptide-based copolymer nanomicelles for co-delivery of doxorubicin and P-gp siRNA into MCF-7 cells

    Energy Technology Data Exchange (ETDEWEB)

    Suo, Aili, E-mail: ailisuo@mail.xjtu.edu.cn [Department of Oncology, The First Affiliated Hospital of Xi' an Jiaotong University, Xi' an 710061 (China); Qian, Junmin, E-mail: jmqian@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Yaping; Liu, Rongrong; Xu, Weijun [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, Hejing [Department of Oncology, The First Affiliated Hospital of Xi' an Jiaotong University, Xi' an 710061 (China)

    2016-05-01

    A comb-like amphiphilic copolymer methoxypolyethylene glycol-graft-poly(L-lysine)-block-poly(L-phenylalanine) (mPEG-g-PLL-b-Phe) was successfully synthesized. To synthesize mPEG-g-PLL-b-Phe, diblock copolymer PLL-b-Phe was first synthesized by successive ring-opening polymerization of α-amino acid N-carboxyanhydrides followed by the removal of benzyloxycarbonyl protecting groups, and then mPEG was grafted onto PLL-b-Phe by reductive amination via Schiff's base formation. The chemical structures of the copolymers were identified by {sup 1}H NMR. mPEG-g-PLL-b-Phe copolymer had a critical micelle concentration of 6.0 mg/L and could self-assemble in an aqueous solution into multicompartment nanomicelles with a mean diameter of approximately 78 nm. The nanomicelles could encapsulate doxorubicin (DOX) through hydrophobic and π–π stacking interactions between DOX molecules and Phe blocks and simultaneously complex P-gp siRNA with cationic PLL blocks via electrostatic interactions. The DOX/P-gp siRNA-loaded nanomicelles showed spherical morphology, possessed narrow particle size distribution and had a mean particle size of 120 nm. The DOX/P-gp siRNA-loaded nanomicelles exhibited pH-responsive release behaviors and displayed accelerated release under acidic conditions. The DOX/P-gp siRNA-loaded nanomicelles were efficiently internalized into MCF-7 cells, and DOX released could successfully reach nuclei. In vitro cytotoxicity assay demonstrated that the DOX/P-gp siRNA-loaded nanomicelles showed a much higher cytotoxicity in MCF-7 cells than DOX-loaded nanomicelles due to their synergistic killing effect and that the blank nanomicelles had good biocompatibility. Thus, the novel comb-like mPEG-g-PLL-b-Phe nanomicelles could be a promising vehicle for co-delivery of chemotherapeutic drug and genetic material. - Highlights: • Comb-like amphiphilic copolymer mPEG-g-PLL-b-Phe was successfully synthesized. • Polypeptide-based copolymer could self-assemble into

  19. Multicompartment micellar aggregates of linear ABC amphiphiles in solvents selective for the C block: A Monte Carlo simulation

    KAUST Repository

    Zhu, Yutian; Yu, Haizhou; Wang, Yongmei; Cui, Jie; Kong, Weixin; Jiang, Wei

    2012-01-01

    the simulations and the detailed phase diagrams for the ABC amphiphiles with different block lengths are obtained. The simulation results reveal that the micellar structure is largely controlled by block length, solvent quality, and incompatibility between

  20. Isentropic expansion and related thermodynamic properties of non-ionic amphiphile-water mixtures.

    Science.gov (United States)

    Reis, João Carlos R; Douhéret, Gérard; Davis, Michael I; Fjellanger, Inger Johanne; Høiland, Harald

    2008-01-28

    A concise thermodynamic formalism is developed for the molar isentropic thermal expansion, ES,m = ( partial differential Vm/ partial differential T)(Sm,x), and the ideal and excess quantities for the molar, apparent molar and partial molar isentropic expansions of binary liquid mixtures. Ultrasound speeds were determined by means of the pulse-echo-overlap method in aqueous mixtures of 2-methylpropan-2-ol at 298.15 K over the entire composition range. These data complement selected extensive literature data on density, isobaric heat capacity and ultrasound speed for 9 amphiphile (methanol, ethanol, propan-1-ol, propan-2-ol, 2-methylpropan-2-ol, ethane-1,2-diol, 2-methoxyethanol, 2-ethoxyethanol or 2-butoxyethanol)-water binary systems, which form the basis of tables listing molar and excess molar isobaric expansions and heat capacities, and molar and excess molar isentropic compressions and expansions at 298.15 K and at 65 fixed mole fractions spanning the entire composition range and fine-grained in the water-rich region. The dependence on composition of these 9 systems is graphically depicted for the excess molar isobaric and isentropic expansions and for the excess partial molar isobaric and isentropic expansions of the amphiphile. The analysis shows that isentropic thermal expansion properties give a much stronger response to amphiphile-water molecular interactions than do their isobaric counterparts. Depending on the pair property-system, the maximum excess molar isentropic value is generally twenty- to a hundred-fold greater than the corresponding maximum isobaric value, and occurs at a lower mole fraction of the amphiphile. Values at infinite dilution of the 9 amphiphiles in water are given for the excess partial molar isobaric heat capacity, isentropic compression, isobaric expansion and isentropic expansion. These values are interpreted in terms of the changes occurring when amphiphile molecules cluster into an oligomeric form. Present results are discussed

  1. Molecular dynamics simulations of membrane deformation induced by amphiphilic helices of Epsin, Sar1p, and Arf1

    Science.gov (United States)

    Li, Zhen-Lu

    2018-03-01

    The N-terminal amphiphilic helices of proteins Epsin, Sar1p, and Arf1 play a critical role in initiating membrane deformation. The interactions of these amphiphilic helices with the lipid membranes are investigated in this study by combining the all-atom and coarse-grained simulations. In the all-atom simulations, the amphiphilic helices of Epsin and Sar1p are found to have a shallower insertion depth into the membrane than the amphiphilic helix of Arf1, but remarkably, the amphiphilic helices of Epsin and Sar1p induce higher asymmetry in the lipid packing between the two monolayers of the membrane. The insertion depth of amphiphilic helix into the membrane is determined not only by the overall hydrophobicity but also by the specific distributions of polar and non-polar residues along the helix. To directly compare their ability to deform the membrane, the coarse-grained simulations are performed to investigate the membrane deformation under the insertion of multiple helices. Project supported by the National Natural Science Foundation of China (Grant Nos. 91427302 and 11474155).

  2. Amphiphilic glycosylated block copolypeptides as macromolecular surfactants in the emulsion polymerization of styrene

    NARCIS (Netherlands)

    Jacobs, Jaco; Gathergood, N.; Heuts, J.P.A.; Heise, A.

    2015-01-01

    Diblock copolymers consisting of poly(L-phenyl alanine) and poly(benzyl-L-glutamate) or poly(CBZ-L-lysine), respectively, were synthesized via sequential NCA polymerization. After deprotection, subsequent partial glycosylation of the glutamic acid and lysine units with galactosamine hydrochloride or

  3. Improved glucose-neopentyl glycol (GNG) amphiphiles for membrane protein solubilization and stabilization.

    Science.gov (United States)

    Cho, Kyung Ho; Bae, Hyoung Eun; Das, Manabendra; Gellman, Samuel H; Chae, Pil Seok

    2014-02-01

    Membrane proteins are inherently amphipathic and undergo dynamic conformational changes for proper function within native membranes. Maintaining the functional structures of these biomacromolecules in aqueous media is necessary for structural studies but difficult to achieve with currently available tools, thus necessitating the development of novel agents with favorable properties. This study introduces several new glucose-neopentyl glycol (GNG) amphiphiles and reveals some agents that display favorable behaviors for the solubilization and stabilization of a large, multi-subunit membrane protein assembly. Furthermore, a detergent structure-property relationship that could serve as a useful guideline for the design of novel amphiphiles is discussed. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Direct investigation of the vectorization properties of amphiphilic cyclodextrins in phospholipid films.

    Science.gov (United States)

    Javierre, Isabelle; Nedyalkov, Mickael; Petkova, Vera; Benattar, Jean Jacques; Weisse, Sandrine; Auzély-Velty, Rachel; Djedaïni-Pilard, Florence; Perly, Bruno

    2002-10-01

    Recently, new cyclodextrin derivatives were synthesized and shown to exhibit strong amphiphilic properties. In this paper, we study the action of these new amphiphilic cyclodextrins on phospholipids. Mixed phospholipid/cyclodextrin derivative films were prepared and studied using X-ray reflectivity for various phospholipid/cyclodextrin ratios. A molar ratio of 3 provides a highly stable film the molecular structure of which has been investigated in detail. The cholesterol tail of the cyclodextrin molecule was found to be anchored into the phospholipid film. The cyclodextrin moieties exposed to the aqueous medium are prone to the addition of the guest molecule Dosulepin, making them of high interest for drug delivery. For this purpose and as an example of a potential application, this cyclodextrin molecular carrier property is also addressed to this complex film architecture.

  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. Coassembly of Lysozyme and Amphiphilic Biomolecules Driven by Unimer-Aggregate Equilibrium.

    Science.gov (United States)

    Tao, Yuanyuan; Ma, Xiaoteng; Cai, Yaqian; Liu, Li; Zhao, Hanying

    2018-04-12

    Synthesis and self-assembly of bioconjugates composed of proteins and synthetic molecules have been widely studied because of the potential applications in medicine, biotechnology, and nanotechnology. One of the challenging research studies in this area is to develop organic solvent-free approaches to the synthesis and self-assembly of amphiphilic bioconjugates. In this research, dialysis-assisted approach, a method based on unimer-aggregate equilibrium, was applied in the coassembly of lysozyme and conjugate of cholesterol and glutathione (Ch-GSH). In phosphate buffer solution, amphiphilic Ch-GSH conjugate self-assembles into vesicles, and the vesicle solution is dialyzed against lysozyme solution. Negatively charged Ch-GSH unimers produced in the unimer-vesicle exchange equilibrium, diffuse across the dialysis membrane and have electrostatic interaction with positively charged lysozyme, resulting in the formation of Ch-GSH-lysozyme bioconjugate. Above a critical concentration, the three-component bioconjugate molecules self-assemble into bioactive vesicles.

  7. 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.

  8. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. A theoretical study of colloidal forces near an amphiphilic polymer brush

    Science.gov (United States)

    Wu, Jianzhong

    2011-03-01

    Polymer-based ``non-stick'' coatings are promising as the next generation of effective, environmentally-friendly marine antifouling systems that minimize nonspecific adsorption of extracellular polymeric substances (EPS). However, design and development of such systems are impeded by the poor knowledge of polymer-mediated interactions of biomacromolecules with the protected substrate. In this work, a polymer density functional theory (DFT) is used to predict the potential of mean force between spherical biomacromolecules and amphiphilic copolymer brushes within a coarse-grained model that captures essential nonspecific interactions such as the molecular excluded volume effects and the hydrophobic energies. The relevance of theoretical results for practical control of the EPS adsorption is discussed in terms of the efficiency of different brush configurations to prevent biofouling. It is shown that the most effective antifouling surface may be accomplished by using amphiphilic brushes with a long hydrophilic backbone and a hydrophobic end at moderate grafting density.

  10. Replication of simulated prebiotic amphiphile vesicles controlled by experimental lipid physicochemical properties

    International Nuclear Information System (INIS)

    Armstrong, Don L; Zidovetzki, Raphael; Markovitch, Omer; Lancet, Doron

    2011-01-01

    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

  11. Theory of the Flower Micelle Formation of Amphiphilic Random and Periodic Copolymers in Solution

    Directory of Open Access Journals (Sweden)

    Takahiro Sato

    2018-01-01

    Full Text Available The mixing Gibbs energy Δgm for the flower-micelle phase of amphiphilic random and periodic (including alternating copolymers was formulated on the basis of the lattice model. The formulated Δgm predicts (1 the inverse proportionality of the aggregation number to the degree of polymerization of the copolymer, (2 the increase of the critical micelle concentration with decreasing the hydrophobe content, and (3 the crossover from the micellization to the liquid–liquid phase separation as the hydrophobe content increases. The transition from the uni-core flower micelle to the multi-core flower necklace as the degree of polymerization increases was also implicitly indicated by the theory. These theoretical results were compared with experimental results for amphiphilic random and alternating copolymers reported so far.

  12. Maltose-neopentyl glycol (MNG) amphiphiles for solubilization, stabilization and crystallization of membrane proteins

    OpenAIRE

    Chae, Pil Seok; Rasmussen, Søren G. F.; Rana, Rohini; Gotfryd, Kamil; Chandra, Richa; Goren, Michael A.; Kruse, Andrew C.; Nurva, Shailika; Loland, Claus J.; Pierre, Yves; Drew, David; Popot, Jean-Luc; Picot, Daniel; Fox, Brian G.; Guan, Lan

    2010-01-01

    The understanding of integral membrane protein (IMP) structure and function is hampered by the difficulty of handling these proteins. Aqueous solubilization, necessary for many types of biophysical analysis, generally requires a detergent to shield the large lipophilic surfaces displayed by native IMPs. Many proteins remain difficult to study owing to a lack of suitable detergents. We introduce a class of amphiphiles, each of which is built around a central quaternary carbon atom derived from...

  13. Optical characterization of CdS nanoparticles embedded into the comb-type amphiphilic graft copolymer

    Science.gov (United States)

    Kalaycı, Özlem A.; Duygulu, Özgür; Hazer, Baki

    2013-01-01

    This study refers to the synthesis and characterization of a novel organic/inorganic hybrid nanocomposite material containing cadmium sulfide (CdS) nanoparticles. For this purpose, a series of polypropylene (PP)-g-polyethylene glycol (PEG), PP-g-PEG comb-type amphiphilic graft copolymers were synthesized. PEGs with Mn = 400, 2000, 3350, and 8000 Da were used and the graft copolymers obtained were coded as PPEG400, PPEG2000, PPEG3350, and PPEG8000. CdS nanoparticles were formed in tetrahydrofuran solution of PP-g-PEG amphiphilic comb-type copolymer by the reaction between aqueous solutions of Na2S and Cd(CH3COO)2 simultaneously. Micelle formation of PPEG2000 comb-type amphiphilic graft copolymer in both solvent/non-solvent (petroleum ether-THF) by transmission electron microscopy (TEM). The optical characteristics, size morphology, phase analysis, and dispersion of CdS nanoparticles embedded in PPEG400, PPEG2000, PPEG3350, and PPEG8000 comb-type amphiphilic graft copolymer micelles were determined by high resolution TEM (HRTEM), energy dispersive spectroscopy, UV-vis spectroscopy, and fluorescence emission spectroscopy techniques. The aggregate size of PPEG2000-CdS is between 10 and 50 nm; however, in the case of PPEG400-CdS, PPEG3350-CdS, and PPEG8000-CdS samples, it is up to approximately 100 nm. The size of CdS quantum dots in the aggregates for PPEG2000 and PPEG8000 samples was observed as 5 nm by HRTEM analysis, and this result was also supported by UV-vis absorbance spectra and fluorescence emission spectra.

  14. Optical characterization of CdS nanoparticles embedded into the comb-type amphiphilic graft copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Kalayc Latin-Small-Letter-Dotless-I , Oezlem A. [Bulent Ecevit University, Department of Physics (Turkey); Duygulu, Oezguer [TUBITAK Marmara Research Center, Materials Institute (Turkey); Hazer, Baki, E-mail: bkhazer@karaelmas.edu.tr [Bulent Ecevit University, Department of Chemistry (Turkey)

    2013-01-15

    This study refers to the synthesis and characterization of a novel organic/inorganic hybrid nanocomposite material containing cadmium sulfide (CdS) nanoparticles. For this purpose, a series of polypropylene (PP)-g-polyethylene glycol (PEG), PP-g-PEG comb-type amphiphilic graft copolymers were synthesized. PEGs with Mn = 400, 2000, 3350, and 8000 Da were used and the graft copolymers obtained were coded as PPEG400, PPEG2000, PPEG3350, and PPEG8000. CdS nanoparticles were formed in tetrahydrofuran solution of PP-g-PEG amphiphilic comb-type copolymer by the reaction between aqueous solutions of Na{sub 2}S and Cd(CH{sub 3}COO){sub 2} simultaneously. Micelle formation of PPEG2000 comb-type amphiphilic graft copolymer in both solvent/non-solvent (petroleum ether-THF) by transmission electron microscopy (TEM). The optical characteristics, size morphology, phase analysis, and dispersion of CdS nanoparticles embedded in PPEG400, PPEG2000, PPEG3350, and PPEG8000 comb-type amphiphilic graft copolymer micelles were determined by high resolution TEM (HRTEM), energy dispersive spectroscopy, UV-vis spectroscopy, and fluorescence emission spectroscopy techniques. The aggregate size of PPEG2000-CdS is between 10 and 50 nm; however, in the case of PPEG400-CdS, PPEG3350-CdS, and PPEG8000-CdS samples, it is up to approximately 100 nm. The size of CdS quantum dots in the aggregates for PPEG2000 and PPEG8000 samples was observed as 5 nm by HRTEM analysis, and this result was also supported by UV-vis absorbance spectra and fluorescence emission spectra.

  15. Optical characterization of CdS nanoparticles embedded into the comb-type amphiphilic graft copolymer

    International Nuclear Information System (INIS)

    Kalaycı, Özlem A.; Duygulu, Özgür; Hazer, Baki

    2013-01-01

    This study refers to the synthesis and characterization of a novel organic/inorganic hybrid nanocomposite material containing cadmium sulfide (CdS) nanoparticles. For this purpose, a series of polypropylene (PP)-g-polyethylene glycol (PEG), PP-g-PEG comb-type amphiphilic graft copolymers were synthesized. PEGs with Mn = 400, 2000, 3350, and 8000 Da were used and the graft copolymers obtained were coded as PPEG400, PPEG2000, PPEG3350, and PPEG8000. CdS nanoparticles were formed in tetrahydrofuran solution of PP-g-PEG amphiphilic comb-type copolymer by the reaction between aqueous solutions of Na 2 S and Cd(CH 3 COO) 2 simultaneously. Micelle formation of PPEG2000 comb-type amphiphilic graft copolymer in both solvent/non-solvent (petroleum ether–THF) by transmission electron microscopy (TEM). The optical characteristics, size morphology, phase analysis, and dispersion of CdS nanoparticles embedded in PPEG400, PPEG2000, PPEG3350, and PPEG8000 comb-type amphiphilic graft copolymer micelles were determined by high resolution TEM (HRTEM), energy dispersive spectroscopy, UV–vis spectroscopy, and fluorescence emission spectroscopy techniques. The aggregate size of PPEG2000-CdS is between 10 and 50 nm; however, in the case of PPEG400-CdS, PPEG3350-CdS, and PPEG8000-CdS samples, it is up to approximately 100 nm. The size of CdS quantum dots in the aggregates for PPEG2000 and PPEG8000 samples was observed as 5 nm by HRTEM analysis, and this result was also supported by UV–vis absorbance spectra and fluorescence emission spectra.

  16. An Experimental and Molecular Dynamics Investigation into the Amphiphilic Nature of Sulforhodamine B

    OpenAIRE

    Polat, Baris E.; Lin, Shangchao; Mendenhall, Jonathan D.; VanVeller, Brett; Langer, Robert; Blankschtein, Daniel

    2011-01-01

    Sulforhodamine B (SRB), a common fluorescent dye, is often considered to be a purely hydrophilic molecule, having no impact on bulk or interfacial properties of aqueous solutions. This assumption is due to the high water solubility of SRB relative to most fluorescent probes. However, in the present study, we demonstrate that SRB is in fact an amphiphile, with the ability to adsorb at an air/water interface and to incorporate into sodium dodecyl sulfate (SDS) micelles. In fact, SRB reduces the...

  17. Vortex-Induced Alignment of a Water Soluble Supramolecular Nanofiber Composed of an Amphiphilic Dendrimer

    Directory of Open Access Journals (Sweden)

    Akihiko Tsuda

    2013-06-01

    Full Text Available We have synthesized a novel amphiphilic naphthalene imide bearing a cationic dendrimer wedge (NID. NID molecules in water self-assemble to form a two-dimensional ribbon, which further coils to give a linear supramolecular nanofiber. The sample solution showed linear dichroism (LD upon stirring of the solution, where NID nanofibers dominantly align at the center of vortex by hydrodynamic interaction with the downward torsional flows.

  18. Metal-ion retention properties of water-soluble amphiphilic block copolymer in double emulsion systems (w/o/w) stabilized by non-ionic surfactants.

    Science.gov (United States)

    Palencia, Manuel; Rivas, Bernabé L

    2011-11-15

    Metal-ion retention properties of water-soluble amphiphilic polymers in presence of double emulsion were studied by diafiltration. Double emulsion systems, water-in-oil-in-water, with a pH gradient between external and internal aqueous phases were prepared. A poly(styrene-co-maleic anhydride) (PSAM) solution at pH 6.0 was added to the external aqueous phase of double emulsion and by application of pressure a divalent metal-ion stream was continuously added. Metal-ions used were Cu(2+) and Cd(2+) at the same pH of polymer solution. According to our results, metal-ion retention is mainly the result of polymer-metal interaction. Interaction between PSMA and reverse emulsion globules is strongly controlled by amount of metal-ions added in the external aqueous phase. In addition, as metal-ion concentration was increased, a negative effect on polymer retention capacity and promotion of flocculation phenomena were produced. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Preparation and characterization of amphiphilic copolymer PVDF-g-PMABS and its application in improving hydrophilicity and protein fouling resistance of PVDF membrane

    Science.gov (United States)

    Chen, Fengtao; Shi, Xingxing; Chen, Xiaobing; Chen, Wenxing

    2018-01-01

    A facile strategy to improve the hydrophilicity and the antifouling properties of poly(vinylidene fluoride) (PVDF) membranes, a functional monomer of 4-methacrylamidobenzenesulfonic acid (MABS), was designed and synthesized through the amidation reaction between 2-methylacryloyl chloride and sulfanilic acid. Utilizing PVDF and the obtained MABS as reaction monomers, a novel amphiphilic copolymer was firstly prepared by radical polymerization method. The resulting PVDF-g-PMABS was used as a hydrophilic additive in the fabrication of PVDF porous membranes via immersion precipitation process. The surface chemical compositions and structure morphologies of as-prepared blend membranes (PVDF-g-PMABS/PVDF) were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. Contact angle measurement and cross-flow permeation test were employed to evaluate the hydrophilicity and antifouling properties of the membranes. It was found that the blend membrane with 4 wt.% PVDF-g-PMABS exhibited a noticeable pure water flux (136.34 L m-2 h-1) and a remarkable flux recovery ratio (FRR) of 98.60% in comparison with the pristine PVDF membrane (63.37 L m-2 h-1 and 38.67%, respectively). The enhanced performance was attributed to the synergetic effects of the strong hydrogen bonding force and the electrostatic repulsion of sulfonic groups against the protein foulants.

  20. 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.

  1. 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.

  2. Anchoring cationic amphiphiles for nucleotide delivery: significance of DNA release from cationic liposomes for transfection.

    Science.gov (United States)

    Hirashima, Naohide; Minatani, Kazuhiro; Hattori, Yoshifumi; Ohwada, Tomohiko; Nakanishi, Mamoru

    2007-06-01

    We have designed and synthesized lithocholic acid-based cationic amphiphile molecules as components of cationic liposomes for gene transfection (lipofection). To study the relationship between the molecular structures of those amphiphilic molecules, particularly the extended hydrophobic appendant (anchor) at the 3-hydroxyl group, and transfection efficiency, we synthesized several lithocholic and isolithocholic acid derivatives, and examined their transfection efficiency. We also compared the physico-chemical properties of cationic liposomes prepared from these derivatives. We found that isolithocholic acid derivatives exhibit higher transfection efficiency than the corresponding lithocholic acid derivatives. This result indicates that the orientation and extension of hydrophobic regions influence the gene transfection process. Isolithocholic acid derivatives showed a high ability to encapsulate DNA in a compact liposome-DNA complex and to protect it from enzymatic degradation. Isolithocholic acid derivatives also facilitated the release of DNA from the liposome-DNA complex, which is a crucial step for DNA entry into the nucleus. Our results show that the transfection efficiency is directly influenced by the ability of the liposome complex to release DNA, rather than by the DNA-encapsulating ability. Molecular modeling revealed that isolithocholic acid derivatives take relatively extended conformations, while the lithocholic acid derivatives take folded structures. Thus, the efficiency of release of DNA from cationic liposomes in the cytoplasm, which contributes to high transfection efficiency, appears to be dependent upon the molecular shape of the cationic amphiphiles.

  3. Amphiphilic carbon dots for sensitive detection, intracellular imaging of Al{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Depeng [State Key Laboratory of Separation Membranes and Membrane Processes, School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Yan, Fanyong, E-mail: yanfanyong@tjpu.edu.cn [State Key Laboratory of Separation Membranes and Membrane Processes, School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Luo, Yunmei [Department of Pharmacology/Key Laboratory for Basic Pharmacology of Ministry of Education, Zunyi Medical College, Guizhou 563000 (China); Ye, Qianghua; Zhou, Siyushan [State Key Laboratory of Separation Membranes and Membrane Processes, School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Chen, Li, E-mail: Chenlis@tjpu.edu.cn [State Key Laboratory of Separation Membranes and Membrane Processes, School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

    2017-02-08

    In this paper, a simple and effective method was designed to synthesize hydrophobic carbon dots. Subsequently, amphiphilic fluorescent carbon dots (A-CDs) were synthesized by further surface modification. The result A-CDs show excellent optical properties with a quantum yield of 16.9%. It was interestingly found that morin (MR) and its fluorescent metal-ion complex (MR-Al{sup 3+}) can successfully coordinate on the surface of A-CDs, the emission of A-CDs completely overlapped the absorption peak of MR-Al{sup 3+}. Thus, the prepared A-CDs can be used as an effective fluorescent probe for Al{sup 3+} based on a fluorescence resonance energy transfer process. The sensing platform can realize real-time detection of Al{sup 3+} within 0.5 min. The fluorescence signals of the system were linearly correlated with the concentration of Al{sup 3+} over a range of 8–20 μM, with a detection limit of 0.113 μM. The method was also successfully applied to image the distribution of Al{sup 3+} in Human Umbilical Vein Endothelial Cells. - Highlights: • Amphiphilic carbon dots were obtained by simply modifying hydrophobic carbon dots. • Amphiphilic carbon dots/morin-Al{sup 3+} was used as a selective turn-on probe for Al{sup 3+}. • The method was employed to intracellular imaging Al{sup 3+} in living cells.

  4. Cylindrical micelles of a POSS amphiphilic dendrimer as nano-reactors for polymerization.

    Science.gov (United States)

    Weng, Jing-Ting; Yeh, Tso-Fan; Samuel, Ashok Zachariah; Huang, Yi-Fan; Sie, Jyun-Hao; Wu, Kuan-Yi; Peng, Chi-How; Hamaguchi, Hiro-O; Wang, Chien-Lung

    2018-02-15

    A low generation amphiphilic dendrimer, POSS-AD, which has a POSS core and eight amphiphilic arms, was synthesized and used as a nano-reactor to produce well-defined polymer nano-cylinders. Confirmed by small-angle X-ray scattering (SAXS), Raman and NMR spectrometry, monodispersed cylindrical micelles that contain a hydrophilic cavity with a diameter of 2.09 nm and a length of 4.26 nm were produced via co-assembling POSS-AD with hydrophilic liquids, such as H 2 O and HEMA in hydrophobic solvents. Taking the HEMA/POSS-AD cylindrical micelles as nano-reactors, polymerization of HEMA within the micelles results in polymer nano-cylinders (POSS-ADNPs) with a diameter of 2.24 nm and a length of 5.02 nm. The study confirmed that despite the inability to maintain specific shape in solution, low generation dendrimers form well-defined nano-containers or nano-reactors, which relies on co-assembling with hydrophilic guest molecules. These nano-reactors are robust enough to maintain their shape during the polymerization of the guest molecules. Polymer nano-cylinders with dimensions less than 10 nm can thus be produced from the HEMA/POSS-AD micelles. Since the chemical structure of low-generation dendrimers and the contents of the co-assembled nano-reactors can be easily adjusted, the concept holds the potential for the further developments of low-generation amphiphilic dendrimers.

  5. 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.

  6. Driving forces for adsorption of amphiphilic peptides to the air-water interface.

    Science.gov (United States)

    Engin, Ozge; Villa, Alessandra; Sayar, Mehmet; Hess, Berk

    2010-09-02

    We have studied the partitioning of amphiphilic peptides at the air-water interface. The free energy of adsorption from bulk to interface was calculated by determining the potential of mean force via atomistic molecular dynamics simulations. To this end a method is introduced to restrain or constrain the center of mass of a group of molecules in a periodic system. The model amphiphilic peptides are composed of alternating valine and asparagine residues. The decomposition of the free energy difference between the bulk and interface is studied for different peptide block lengths. Our analysis revealed that for short amphiphilic peptides the surface driving force dominantly stems from the dehydration of hydrophobic side chains. The only opposing force is associated with the loss of orientational freedom of the peptide at the interface. For the peptides studied, the free energy difference scales linearly with the size of the molecule, since the peptides mainly adopt extended conformations both in bulk and at the interface. The free energy difference depends strongly on the water model, which can be rationalized through the hydration thermodynamics of hydrophobic solutes. Finally, we measured the reduction of the surface tension associated with complete coverage of the interface with peptides.

  7. 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.

  8. Physical deposition behavior of stiff amphiphilic polyelectrolytes in an external electric field

    Science.gov (United States)

    Hu, Dongmei; Zuo, Chuncheng; Cao, Qianqian; Chen, Hongli

    2017-08-01

    Coarse-grained molecular dynamics simulations are conducted to study the physical deposition behavior of stiff amphiphilic polyelectrolytes (APEs) in an external electric field. The effects of chain stiffness, the charge distribution of a hydrophilic block, and electric field strength are investigated. Amphiphilic multilayers, which consist of a monolayer of adsorbed hydrophilic monomers (HLMs), a hydrophobic layer, and another hydrophilic layer, are formed in a selective solvent. All cases exhibit locally ordered hydrophilic monolayers. Two kinds of hydrophobic micelles are distinguished based on local structures. Stripe and network hydrophobic patterns are formed in individual cases. Increasing the chain stiffness decreases the thickness of the deposited layer, the lateral size of the hydrophobic micelles, and the amount of deposition. Increasing the number of positively charged HLMs in a single chain has the same effect as increasing chain stiffness. Moreover, when applied normally to the substrate, the electric field compresses the deposited structures and increases the amount of deposition by pulling more PEs toward the substrate. A stronger electric field also facilitates the formation of a thinner and more ordered hydrophilic adsorption layer. These estimates help us explore how to tailor patterned nano-surfaces, nano-interfaces, or amphiphilic nanostructures by physically depositing semi-flexible APEs which is of crucial importance in physical sciences, life sciences and nanotechnology.

  9. Design and application of cationic amphiphilic β-cyclodextrin derivatives as gene delivery vectors

    Science.gov (United States)

    Wan, Ning; Huan, Meng-Lei; Ma, Xi-Xi; Jing, Zi-Wei; Zhang, Ya-Xuan; Li, Chen; Zhou, Si-Yuan; Zhang, Bang-Le

    2017-11-01

    The nano self-assembly profiles of amphiphilic gene delivery vectors could improve the density of local cationic head groups to promote their DNA condensation capability and enhance the interaction between cell membrane and hydrophobic tails, thus increasing cellular uptake and gene transfection. In this paper, two series of cationic amphiphilic β-cyclodextrin (β-CD) derivatives were designed and synthesized by using 6-mono-OTs-β-CD (1) as the precursor to construct amphiphilic gene vectors with different building blocks in a selective and controlled manner. The effect of different type and degree of cationic head groups on transfection and the endocytic mechanism of β-CD derivatives/DNA nanocomplexes were also investigated. The results demonstrated that the designed β-cyclodextrin derivatives were able to compact DNA to form stable nanocomplexes and exhibited low cytotoxicity. Among them, PEI-1 with PEI head group showed enhanced transfection activity, significantly higher than commercially available agent PEI25000 especially in the presence of serum, showing potential application prospects in clinical trials. Moreover, the endocytic uptake mechanism involved in the gene transfection of PEI-1 was mainly through caveolae-mediated endocytosis, which could avoid the lysosomal degradation of loaded gene, and had great importance for improving gene transfection activity.

  10. Self-Assembled Nanocarriers Based on Amphiphilic Natural Polymers for Anti- Cancer Drug Delivery Applications.

    Science.gov (United States)

    Sabra, Sally; Abdelmoneem, Mona; Abdelwakil, Mahmoud; Mabrouk, Moustafa Taha; Anwar, Doaa; Mohamed, Rania; Khattab, Sherine; Bekhit, Adnan; Elkhodairy, Kadria; Freag, May; Elzoghby, Ahmed

    2017-01-01

    Micellization provides numerous merits for the delivery of water insoluble anti-cancer therapeutic agents including a nanosized 'core-shell' drug delivery system. Recently, hydrophobically-modified polysaccharides and proteins are attracting much attention as micelle forming polymers to entrap poorly soluble anti-cancer drugs. By virtue of their small size, the self-assembled micelles can passively target tumor tissues via enhanced permeation and retention effect (EPR). Moreover, the amphiphilic micelles can be exploited for active-targeted drug delivery by attaching specific targeting ligands to the outer micellar hydrophilic surface. Here, we review the conjugation techniques, drug loading methods, physicochemical characteristics of the most important amphiphilic polysaccharides and proteins used as anti-cancer drug delivery systems. Attention focuses on the mechanisms of tumor-targeting and enhanced anti-tumor efficacy of the encapsulated drugs. This review will highlight the remarkable advances of hydrophobized polysaccharide and protein micelles and their potential applications as anti-cancer drug delivery nanosystems. Micellar nanocarriers fabricated from amphiphilic natural polymers hold great promise as vehicles for anti-cancer drugs. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  11. Drug-Induced Morphology Switch in Drug Delivery Systems Based on Poly(2-oxazoline)s

    Science.gov (United States)

    2015-01-01

    Defined aggregates of polymers such as polymeric micelles are of great importance in the development of pharmaceutical formulations. The amount of drug that can be formulated by a drug delivery system is an important issue, and most drug delivery systems suffer from their relatively low drug-loading capacity. However, as the loading capacities increase, i.e., promoted by good drug–polymer interactions, the drug may affect the morphology and stability of the micellar system. We investigated this effect in a prominent system with very high capacity for hydrophobic drugs and found extraordinary stability as well as a profound morphology change upon incorporation of paclitaxel into micelles of amphiphilic ABA poly(2-oxazoline) triblock copolymers. The hydrophilic blocks A comprised poly(2-methyl-2-oxazoline), while the middle blocks B were either just barely hydrophobic poly(2-n-butyl-2-oxazoline) or highly hydrophobic poly(2-n-nonyl-2-oxazoline). The aggregation behavior of both polymers and their formulations with varying paclitaxel contents were investigated by means of dynamic light scattering, atomic force microscopy, (cryogenic) transmission electron microscopy, and small-angle neutron scattering. While without drug, wormlike micelles were present, after incorporation of small amounts of drugs only spherical morphologies remained. Furthermore, the much more hydrophobic poly(2-n-nonyl-2-oxazoline)-containing triblock copolymer exhibited only half the capacity for paclitaxel than the poly(2-n-butyl-2-oxazoline)-containing copolymer along with a lower stability. In the latter, contents of paclitaxel of 8 wt % or higher resulted in a raspberry-like micellar core. PMID:24548260

  12. 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.

  13. Fabrication of honeycomb-structured poly(ethylene glycol)-block-poly(lactic acid) porous films and biomedical applications for cell growth

    International Nuclear Information System (INIS)

    Yao, Bingjian; Zhu, Qingzeng; Yao, Linli; Hao, Jingcheng

    2015-01-01

    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 3 :3.0 × 10 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

  14. Surface morphology and dewettability of self-organized thermosets involving epoxy and POSS-capped poly(ethylene oxide) telechelics

    International Nuclear Information System (INIS)

    Wang, Lei; Zheng, Sixun

    2012-01-01

    A heptaphenyl polyhedral oligomeric silsesquioxane-capped poly(ethylene oxide) (POSS-capped PEO) telechelics was synthesized via the Huisgen 1,3-dipolar cycloaddition between 3-azidopropylheptaphenyl POSS and α,ω-dialkynyl-terminated poly(ethylene oxide). The organic–inorganic amphiphile was incorporated into epoxy to obtain the organic–inorganic nanocomposites. The morphology of the nanocomposites was investigated by means of atomic force microscopy (AFM) and dynamic mechanical thermal analysis (DMTA). It was found that the epoxy thermosets containing POSS-capped PEO telechelics were microphase-separated. The formation of the nanophases in the thermosets followed a self-assembly mechanism. The static contact angle measurements show that the nanocomposites displayed a significant enhancement in surface hydrophobicity as well as reduction in surface free energy. The improvement in surface dewettability was ascribed to the enrichment of POSS cages at the surface of the nanocomposites and the formation of the specific surface morphology as evidenced by X-ray photoelectron spectroscopy (XPS) and surface atomic force microscopy (AFM). -- Highlights: ► POSS-capped PEO telechelics was synthesized via click chemistry approach. ► The organic–inorganic amphiphile can be self-assembled into the nanophases in epoxy. ► The hybrid nanocomposites were successfully prepared via a self-assembly approach. ► The nanocomposites displayed a significant enhancement in surface hydrophobicity.

  15. 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 p......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...

  16. Production of BSA-poly(ethyl cyanoacrylate) nanoparticles as a coating material that improves wetting property.

    Science.gov (United States)

    Kim, S; Evans, K; Biswas, A

    2013-07-01

    Alkyl cyanoacrylates have long been used for the synthesis of colloidal nanoparticles. In the involved polymerization reaction, hydroxyl ions derived from dissociation of water have been used as an initiator. In the current research, an animal protein, bovine serum albumin (BSA) molecules were utilized as initiator for the polymerization. Following this reaction scheme, hydrophobic poly(ethyl cyanoacrylate)s were covalently bound to BSA, which is hydrophilic. Therefore, the resultant copolymer was amphiphilic in nature, and formed nanoparticles in the reaction medium. The suspension containing these nanoparticles showed an excellent coating capability on the surface of hydrophobic materials. A simple spray coating changed the wetting property of the material instantly and dramatically. Published by Elsevier B.V.

  17. 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.

  18. 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

    . At the 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...... synchrotron radiation. Compression beyond the collapse point does not change the XR data, showing that the film is unchanged at the molecular level, even at areas less than half of that of the collapse. This leads to the conclusion that few macroscopic collapse sites are responsible for reversibly removing...

  19. A spectroscopic method to estimate the binding potency of amphiphile assemblies

    Czech Academy of Sciences Publication Activity Database

    Gauger, D. R.; Andrushchenko, Valery; Bouř, Petr; Pohle, W.

    2010-01-01

    Roč. 398, č. 2 (2010), s. 1109-1123 ISSN 1618-2642 R&D Projects: GA ČR GA203/06/0420; GA ČR GA202/07/0732; GA ČR GAP208/10/0559; GA AV ČR IAA400550702; GA AV ČR IAA400550701 Institutional research plan: CEZ:AV0Z40550506 Keywords : miccels * amphiphile assemblies * molecular dynamics * infrared spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.841, year: 2010

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

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  1. Macroscopic alignment of graphene stacks by Langmuir-Blodgett deposition of amphiphilic hexabenzocoronenes

    DEFF Research Database (Denmark)

    Laursen, B.W.; Nørgaard, K.; Reitzel, N.

    2004-01-01

    ). Grazing-incidence X-ray diffraction (GIXD) and X-ray reflectivity, both utilizing synchrotron radiation, show that these amphiphilic HBCs form well-defined Langmuir monolayers at the air-water interface, with pi-stacked columnar structure where the HBC cores are rotated around the surface normal...... and tilted relative to the water surface. The intercolumnar distance is 20 A. The HBCs are confined to a layer lying on top of the layer of polar groups that are in contact with the water subphase. Efficient transfer of the monolayer of the anthraquinone-substituted HBC derivative to hydrophobic quartz...

  2. Effects of hydrophobic drug-polyesteric core interactions on drug loading and release properties of poly(ethylene glycol)-polyester-poly(ethylene glycol) triblock core-shell nanoparticles

    International Nuclear Information System (INIS)

    Khoee, Sepideh; Hassanzadeh, Salman; Goliaie, Bahram

    2007-01-01

    BAB amphiphilic triblock copolymers consisting of poly(ethylene glycol) (B) (PEG) as the hydrophilic segment and different polyesters (A) as the hydrophobic block were prepared by a polycondensation reaction as efficient model core-shell nanoparticles to assay the effect of interactions between the hydrophobic drug and the polyesteric core in terms of drug loading content and release profile. PEG-poly(hexylene adipate)-PEG (PEG-PHA-PEG) and PEG-poly(butylene adipate)-PEG (PEG-PBA-PEG) to PEG-poly(ethylene adipate)-PEG (PEG-PEA-PEG) core-shell type nanoparticles entrapping quercetin (an anticarcinogenic, allergy inhibitor and antibacterial agent), were prepared by a nanoprecipitation method and characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and x-ray diffraction (XRD) techniques. It was found that the obtained nanoparticles showed a smooth surface and spherical shape with controllable sizes in the range of 64-74 nm, while drug loading varied from 7.24% to 19% depending on the copolymer composition and the preparation conditions. The in vitro release behaviour exhibited a sustained release and was affected by the polymer-drug interactions. UV studies revealed the presence of hydrogen bonding as the main existing interaction between quercetin and polyesters in the nanosphere cores

  3. Self-assembly in poly(dimethylsiloxane)-poly(ethylene oxide) block copolymer template directed synthesis of Linde type A zeolite.

    Science.gov (United States)

    Bonaccorsi, Lucio; Calandra, Pietro; Kiselev, Mikhail A; Amenitsch, Heinz; Proverbio, Edoardo; Lombardo, Domenico

    2013-06-11

    We describe the hydrothermal synthesis of zeolite Linde type A (LTA) submicrometer particles using a water-soluble amphiphilic block copolymer of poly(dimethylsiloxane)-b-poly(ethylene oxide) as a template. The formation and growth of the intermediate aggregates in the presence of the diblock copolymer have been monitored by small-angle X-ray scattering (SAXS) above the critical micellar concentration at a constant temperature of 45 °C. The early stage of the growth process was characterized by the incorporation of the zeolite LTA components into the surface of the block copolymer micellar aggregates with the formation of primary units of 4.8 nm with a core-shell morphology. During this period, restricted to an initial time of 1-3 h, the core-shell structure of the particles does not show significant changes, while a subsequent aggregation process among these primary units takes place. A shape transition of the SAXS profile at the late stage of the synthesis has been connected with an aggregation process among primary units that leads to the formation of large clusters with fractal characteristics. The formation of large supramolecular assemblies was finally verified by scanning electron microscopy, which evidenced the presence of submicrometer aggregates with size ranging between 100 and 300 nm, while X-ray diffraction confirmed the presence of crystalline zeolite LTA. The main finding of our results gives novel insight into the mechanism of formation of organic-inorganic mesoporous materials based on the use of a soft interacting nanotemplate as well as stimulates the investigation of alternative protocols for the synthesis of novel hybrid materials with new characteristics and properties.

  4. Spider-web amphiphiles as artificial lipid clusters: design, synthesis, and accommodation of lipid components at the air-water interface.

    Science.gov (United States)

    Ariga, Katsuhiko; Urakawa, Toshihiro; Michiue, Atsuo; Kikuchi, Jun-ichi

    2004-08-03

    As a novel category of two-dimensional lipid clusters, dendrimers having an amphiphilic structure in every unit were synthesized and labeled "spider-web amphiphiles". Amphiphilic units based on a Lys-Lys-Glu tripeptide with hydrophobic tails at the C-terminal and a polar head at the N-terminal are dendrically connected through stepwise peptide coupling. This structural design allowed us to separately introduce the polar head and hydrophobic tails. Accordingly, we demonstrated the synthesis of the spider-web amphiphile series in three combinations: acetyl head/C16 chain, acetyl head/C18 chain, and ammonium head/C16 chain. All the spider-web amphiphiles were synthesized in satisfactory yields, and characterized by 1H NMR, MALDI-TOFMS, GPC, and elemental analyses. Surface pressure (pi)-molecular area (A) isotherms showed the formation of expanded monolayers except for the C18-chain amphiphile at 10 degrees C, for which the molecular area in the condensed phase is consistent with the cross-sectional area assigned for all the alkyl chains. In all the spider-web amphiphiles, the molecular areas at a given pressure in the expanded phase increased in proportion to the number of units, indicating that alkyl chains freely fill the inner space of the dendritic core. The mixing of octadecanoic acid with the spider-web amphiphiles at the air-water interface induced condensation of the molecular area. From the molecular area analysis, the inclusion of the octadecanoic acid bears a stoichiometric characteristic; i.e., the number of captured octadecanoic acids in the spider-web amphiphile roughly agrees with the number of branching points in the spider-web amphiphile.

  5. Transport properties of poly(GACT)–poly(CTGA)

    Indian Academy of Sciences (India)

    In this paper, based on the tight-binding Hamiltonian model and within the framework of a generalized Green's function technique, the electronic conduction through the poly(GACT)–poly(CTGA) DNA molecule in SWNT/DNA/SWNT structure has been numerically investigated. In a ladder model, we consider DNA as a ...

  6. Solar CalPoly

    Energy Technology Data Exchange (ETDEWEB)

    Stannard, Sandra [California Polytechnic State Univ., San Luis Obispo, CA (United States)

    2016-06-15

    The target budget of INhouse was about $650,000 for all materials and student expenses of the Solar Decathlon competition. In order to reach our goal, Cal Poly students and faculty worked with the College of Architecture and Environmental Design’s External Relations office to actively fundraise for INhouse. Students connected with Cal Poly alumni through phone calls, postal mail, email, and live presentations to reach as many alumni in the state of California as possible. Before construction begun, students and faculty met on a weekly basis to determine what brands of materials for the home to use and who would be responsible for reaching out to the company to seek a donation. Our College of Architecture and Environmental Design’s administration was essential in helping us fundraise. For some time, the college was hoping to depend on about half of our fundraising expenses to be covered through the sale of INhouse. However, plans to sell the home fell through during the design development phase; the college turned to the sale of a different asset in to help us meet our goal. If we were to do this project again, completing the design concept and securing a future location of our home sooner would have enhanced our fundraising activities.

  7. Positron annihilation lifetime spectroscopy (PALS) as a characterization technique for nanostructured self-assembled amphiphile systems.

    Science.gov (United States)

    Dong, Aurelia W; Pascual-Izarra, Carlos; Pas, Steven J; Hill, Anita J; Boyd, Ben J; Drummond, Calum J

    2009-01-08

    Positron annihilation lifetime spectroscopy (PALS) has potential as a novel rapid characterization method for self-assembly amphiphile systems; however, a lack of systematic correlation of PALS parameters with structural attributes has limited its more widespread application. In this study, using the well-characterized phytantriol/water and the phytantriol/vitamin E acetate/water self-assembly amphiphile systems, the impact of systematic structural changes controlled by changes in composition and temperature on PALS parameters has been studied. The PALS parameters (orthopositronium (oPs) lifetime and intensity signatures) were shown to be sensitive to the molecular packing and mobility of the self-assembled lipid molecules in various lyotropic liquid crystalline phases, enabling differentiation between liquid crystalline structures. The oPs lifetime, related to the molecular packing and mobility, is correlated with rheological properties of the individual mesophases. The oPs lifetime links the lipid chain packing and mobility in the various mesophases to resultant macroscopic properties, such as permeability, which is critical for the use of these mesophase structures as diffusion-controlled release matrices for active liposoluble compounds.

  8. Probing the amphiphile micellar to hexagonal phase transition using Positron Annihilation Lifetime Spectroscopy.

    Science.gov (United States)

    Dong, Aurelia W; Fong, Celesta; Hill, Anita J; Boyd, Ben J; Drummond, Calum J

    2013-07-15

    Positron Annihilation Lifetime Spectroscopy (PALS) has been utilised only sparingly for structural characterisation in self assembled materials. Inconsistencies in approaches to experimental configuration and data analysis between studies has complicated comparisons between studies, meaning that the technique has not provided a cohesive data set across the study of different self assembled systems that advance the technique towards an important tool in soft matter research. In the current work a systematic study was conducted using ionic and non-ionic micellar systems with increasing surfactant concentration to probe positron behaviour on changes between micellar phase structures, and data analysed using contemporary approaches to fit four component spectra. A characteristic orthopositronium lifetime (in the organic regions) of 3.5±0.2 ns was obtained for the hexagonal phase for surfactants with C12 alkyl chains. Chemical quenching of the positron species was also observed for systems with ionic amphiphiles. The application of PALS has also highlighted an inconsistency in the published phase diagram for the octa(ethylene oxide) monododecyl ether (C12EO8) system. These results provide new insight into how the physical properties of micellar systems can be related to PALS parameters and means that the PALS technique can be applied to other more complex self-assembled amphiphile systems. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Synthesis of an amphiphilic rhodamine derivative and characterization of its solution and thin film properties

    International Nuclear Information System (INIS)

    Aviv, Hagit; Harazi, Sivan; Schiff, Dillon; Ramon, Yoni; Tischler, Yaakov R.

    2014-01-01

    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

  10. 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.

  11. 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.

  12. Dynamic stability of nano-fibers self-assembled from short amphiphilic A6D peptides.

    Science.gov (United States)

    Nikoofard, Narges; Maghsoodi, Fahimeh

    2018-04-07

    Self-assembly of A 6 D amphiphilic peptides in explicit water is studied by using coarse-grained molecular dynamics simulations. It is observed that the self-assembly of randomly distributed A 6 D peptides leads to the formation of a network of nano-fibers. Two other simulations with cylindrical nano-fibers as the initial configuration show the dynamic stability of the self-assembled nano-fibers. As a striking feature, notable fluctuations occur along the axes of the nano-fibers. Depending on the number of peptides per unit length of the nano-fiber, flat-shaped bulges or spiral shapes along the nano-fiber axis are observed at the fluctuations. Analysis of the particle distribution around the nano-fiber indicates that the hydrophobic core and the hydrophilic shell of the nano-structure are preserved in both simulations. The size of the deformations and their correlation times are different in the two simulations. This study gives new insights into the dynamics of the self-assembled nano-structures of short amphiphilic peptides.

  13. 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.

  14. Discriminating binding and positioning of amphiphiles to lipid bilayers by {sup 1}H NMR

    Energy Technology Data Exchange (ETDEWEB)

    Evanics, F. [Department of Chemistry, University of Toronto, UTM, 3359 Mississauga Rd. North Mississauga, Ont., L5L 1C6 (Canada); Prosser, R.S. [Department of Chemistry, University of Toronto, UTM, 3359 Mississauga Rd. North Mississauga, Ont., L5L 1C6 (Canada)]. E-mail: sprosser@utm.utoronto.ca

    2005-04-04

    The binding and positioning in lipid bilayers of three well-known drugs--imipramine, nicotine, and caffeine--have been studied using {sup 1}H NMR. The membrane model system consisted of 'fast-tumbling' lipid bicelles, in which a bilayered lipid domain, composed of the unsaturated lipid, 1,2-dimyristelaidoyl-sn-glycero-3-phosphocholine (DMLPC) was surrounded by a rim of deuterated detergent-like lipids, consisting of 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC-d22). Binding and immersion depth information was obtained by three experiments. (1) {sup 1}H chemical shift perturbations, upon transfer of the amphiphiles from water to a bicelle mixture, were used to estimate regions of the amphiphiles that interact with the membrane. (2) Water contact to resolvable protons was measured through a Nuclear Overhauser Effect (NOE) between water and resolvable drug and lipid resonances. In the case of both lipids and membrane bound drugs, positive NOEs with large cross-relaxation rates were measured for most resonances originating from the membrane hydrophilic region, while negative NOEs were observed predominantly to resonances in the hydrophobic region of the membrane. (3) {sup 1}H NMR measurements of oxygen-induced (paramagnetic) spin-lattice relaxation rates, which are known to increase with membrane immersion depth, were used to corroborate conclusions based on chemical shift perturbations and water-ligand NOEs.

  15. Superior Antifouling Performance of a Zwitterionic Peptide Compared to an Amphiphilic, Non-Ionic Peptide.

    Science.gov (United States)

    Ye, Huijun; Wang, Libing; Huang, Renliang; Su, Rongxin; Liu, Boshi; Qi, Wei; He, Zhimin

    2015-10-14

    The aim of this study was to explore the influence of amphiphilic and zwitterionic structures on the resistance of protein adsorption to peptide self-assembled monolayers (SAMs) and gain insight into the associated antifouling mechanism. Two kinds of cysteine-terminated heptapeptides were studied. One peptide had alternating hydrophobic and hydrophilic residues with an amphiphilic sequence of CYSYSYS. The other peptide (CRERERE) was zwitterionic. Both peptides were covalently attached onto gold substrates via gold-thiol bond formation. Surface plasmon resonance analysis results showed that both peptide SAMs had ultralow or low protein adsorption amounts of 1.97-11.78 ng/cm2 in the presence of single proteins. The zwitterionic peptide showed relatively higher antifouling ability with single proteins and natural complex protein media. We performed molecular dynamics simulations to understand their respective antifouling behaviors. The results indicated that strong surface hydration of peptide SAMs contributes to fouling resistance by impeding interactions with proteins. Compared to the CYSYSYS peptide, more water molecules were predicted to form hydrogen-bonding interactions with the zwitterionic CRERERE peptide, which is in agreement with the antifouling test results. These findings reveal a clear relation between peptide structures and resistance to protein adsorption, facilitating the development of novel peptide-containing antifouling materials.

  16. Coating of reverse osmosis membranes with amphiphilic copolymers for biofouling control

    KAUST Repository

    Bucs, Szilard

    2017-05-30

    Surface coating of membranes may be a promising option to control biofilm development and biofouling impact on membrane performance of spiral-wound reverse osmosis (RO) systems. The objective of this study was to investigate the impact of an amphiphilic copolymer coating on biofilm formation and biofouling control. The coating was composed of both hydrophilic and hydrophobic monomers hydroxyethyl methacrylate (HEMA) and perfluorodecyl acrylate (PFA), respectively. Commercial RO membranes were coated with HEMA-PFA copolymer film. Long and short term biofouling studies with coated and uncoated membranes and feed spacer were performed using membrane fouling simulators (MFSs) operated in parallel, fed with water containing nutrients. For the long-term studies pressure drop development in time was monitored and after eight days the MFSs were opened and the accumulated biofilm on the membrane and spacer sheets was quantified and characterized. The presence of the membrane coating was determined using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Results showed that the amphiphilic coating (i) delayed biofouling (a lower pressure drop increase by a factor of 3 and a lower accumulated active biomass amount by a factor of 6), (ii) influenced the biofilm composition (23% lower polysaccharides and 132% higher protein content) and (iii) was still completely present on the membrane at the end of the biofouling study, showing that the coating was strongly attached to the membrane surface. Using coated membranes and feed spacers in combination with advanced cleaning strategies may be a suitable way to control biofouling.

  17. Dynamic stability of nano-fibers self-assembled from short amphiphilic A6D peptides

    Science.gov (United States)

    Nikoofard, Narges; Maghsoodi, Fahimeh

    2018-04-01

    Self-assembly of A6D amphiphilic peptides in explicit water is studied by using coarse-grained molecular dynamics simulations. It is observed that the self-assembly of randomly distributed A6D peptides leads to the formation of a network of nano-fibers. Two other simulations with cylindrical nano-fibers as the initial configuration show the dynamic stability of the self-assembled nano-fibers. As a striking feature, notable fluctuations occur along the axes of the nano-fibers. Depending on the number of peptides per unit length of the nano-fiber, flat-shaped bulges or spiral shapes along the nano-fiber axis are observed at the fluctuations. Analysis of the particle distribution around the nano-fiber indicates that the hydrophobic core and the hydrophilic shell of the nano-structure are preserved in both simulations. The size of the deformations and their correlation times are different in the two simulations. This study gives new insights into the dynamics of the self-assembled nano-structures of short amphiphilic peptides.

  18. Block versus Random Amphiphilic Glycopolymer Nanopaticles as Glucose-Responsive Vehicles.

    Science.gov (United States)

    Guo, Qianqian; Zhang, Tianqi; An, Jinxia; Wu, Zhongming; Zhao, Yu; Dai, Xiaomei; Zhang, Xinge; Li, Chaoxing

    2015-10-12

    To explore the effect of polymer structure on their self-assembled aggregates and their unique characteristics, this study was devoted to developing a series of amphiphilic block and random phenylboronic acid-based glycopolymers by RAFT polymerization. The amphiphilic glycopolymers were successfully self-assembled into spherically shaped nanoparticles with narrow size distribution in aqueous solution. For block and random copolymers with similar monomer compositions, block copolymer nanoparticles exhibited a more regular transmittance change with the increasing glucose level, while a more evident variation of size and quicker decreasing tendency in I/I0 behavior in different glucose media were observed for random copolymer nanoparticles. Cell viability of all the polymer nanoparticles investigated by MTT assay was higher than 80%, indicating that both block and random copolymers had good cytocompatibility. Insulin could be encapsulated into both nanoparticles, and insulin release rate for random glycopolymer was slightly quicker than that for the block ones. We speculate that different chain conformations between block and random glycopolymers play an important role in self-assembled nanoaggregates and underlying glucose-sensitive behavior.

  19. Sodium effect on self-organization of amphiphilic carboxylates: formation of structured micelles and superlattices.

    Science.gov (United States)

    Rosenlehner, Karin; Schade, Boris; Böttcher, Christoph; Jäger, Christof M; Clark, Timothy; Heinemann, Frank W; Hirsch, Andreas

    2010-08-16

    Not only the self-aggregation of dendritic polycarboxylates into structurally persistent micelles, but also that of the micelles themselves into superlattices is controlled by alkali-metal counterions and shows a pronounced sodium effect. Our combined experimental and computational work has revealed the formation of superlattices for the first time. The behavior of a variety of amphiphilic carboxylates and the different effects of the alkali cations Li(+), Na(+), and K(+) have been investigated by conductivity measurements, cryogenic transmission electron microscopy (cryo-TEM), and molecular-dynamics (MD) simulations. Together, these show that sodium salts of the amphiphiles give the most stable micelles, followed by lithium and potassium. Our results suggest that ion multiplets in bridging positions, rather than contact ion pairs, are responsible for the enhanced stability and the formation of hexagonally ordered superlattices with sodium counterions. Potassium ions do not form such ion multiplets and cannot therefore induce aggregation of the micelles. This sodium effect has far-reaching consequences for a large number of biological and technical systems and sheds new light on the origin of specific-ion effects.

  20. Coating of reverse osmosis membranes with amphiphilic copolymers for biofouling control

    KAUST Repository

    Bucs, Szilard; Valladares Linares, Rodrigo; Siddiqui, Amber; Matin, Asif; Khan, Zafarullah; van Loosdrecht, Mark C.M.; Yang, Rong; Wang, Minghui; Gleason, Karen K.; Kruithof, Joop C.; Vrouwenvelder, Johannes S.

    2017-01-01

    Surface coating of membranes may be a promising option to control biofilm development and biofouling impact on membrane performance of spiral-wound reverse osmosis (RO) systems. The objective of this study was to investigate the impact of an amphiphilic copolymer coating on biofilm formation and biofouling control. The coating was composed of both hydrophilic and hydrophobic monomers hydroxyethyl methacrylate (HEMA) and perfluorodecyl acrylate (PFA), respectively. Commercial RO membranes were coated with HEMA-PFA copolymer film. Long and short term biofouling studies with coated and uncoated membranes and feed spacer were performed using membrane fouling simulators (MFSs) operated in parallel, fed with water containing nutrients. For the long-term studies pressure drop development in time was monitored and after eight days the MFSs were opened and the accumulated biofilm on the membrane and spacer sheets was quantified and characterized. The presence of the membrane coating was determined using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Results showed that the amphiphilic coating (i) delayed biofouling (a lower pressure drop increase by a factor of 3 and a lower accumulated active biomass amount by a factor of 6), (ii) influenced the biofilm composition (23% lower polysaccharides and 132% higher protein content) and (iii) was still completely present on the membrane at the end of the biofouling study, showing that the coating was strongly attached to the membrane surface. Using coated membranes and feed spacers in combination with advanced cleaning strategies may be a suitable way to control biofouling.

  1. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    International Nuclear Information System (INIS)

    Varanasi, S. R.; John, A.; Guskova, O. A.; Sommer, J.-U.

    2015-01-01

    Fullerene C 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 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 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

  2. Poly(alkyl acrylate) nonparticles

    International Nuclear Information System (INIS)

    Kreuter, J.

    1985-01-01

    This study deals with the preparation of poly(alkyl acrylic) and poly(alkyl cyanocrylic) nanoparticles. Nonoparticles are solid colloidal particles, consisting of macromolecular materials in which drugs or biologically active materials are dissolved, entrapped, and encapsulated, and/or to which the active substance is adsorbed or attached. Poly(alkyl acrylic) nanoparticles are much more slowly biodegradable than poly(alkyl cyanoacrylate) nanoparticles, and are thus more suitable for drug delivery purposes. Poly(methyl methacrylate) is the material of choice for the use of nanoparticles as an adjuvant for vaccines and are produced by emulsifier-free polymerization in aqueous media. The polymerization, which can be initiated with gamma rays or with potassium peroxodisulfate, is described

  3. Preparation of nanogels by radiation-induced cross-linking of interpolymer complexes of poly (acrylic acid) with poly (vinyl pyrrolidone) in aqueous medium

    Science.gov (United States)

    Ghaffarlou, Mohammadreza; Sütekin, S. Duygu; Güven, Olgun

    2018-01-01

    Functional nanogels were prepared from interpolymer complexes (IPC) of poly (vinyl pyrrolidone) and poly (acrylic acid) by gamma irradiation of their aqueous solutions. The coil size of IPCs prepared under different experimental conditions (polymer molecular weight, concentration, mixing ratios, pH and temperature) were measured by Dynamic Light Scattering (DLS) technique prior to irradiation. At relatively low absorbed doses of 5 and 10 kGy, IPC nanogels with a range of 30-250 nm diameters, -12 to -28 mV zeta potentials and polydispersities lower than 0.17 were obtained. The sizes of the nanogels were found to be smaller than the size of the precursor IPC coil sizes (40-300 nm) due to the formation of intra-chain crosslinks. Thus a recipe of preparing multifunctional nanogels with double amphiphilic properties carrying polyacidic and nonionic polymer structures with the range of above listed properties has been developed. These nanogels show narrow size distribution and high colloidal stability increasing their potential to be used as biocompatible drug carriers with controlled-release properties. PVP-PAA IPC nanogels were characterized by dynamic light scattering (DLS), atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques.

  4. Poly(ethyl glyoxylate)-Poly(ethylene oxide) Nanoparticles: Stimuli-Responsive Drug Release via End-to-End Polyglyoxylate Depolymerization.

    Science.gov (United States)

    Fan, Bo; Gillies, Elizabeth R

    2017-08-07

    The ability to disrupt polymer assemblies in response to specific stimuli provides the potential to release drugs selectively at certain sites or conditions in vivo. However, most stimuli-responsive delivery systems require many stimuli-initiated events to release drugs. "Self-immolative polymers" offer the potential to provide amplified responses to stimuli as they undergo complete end-to-end depolymerization following the cleavage of a single end-cap. Herein, linker end-caps were developed to conjugate self-immolative poly(ethyl glyoxylate) (PEtG) with poly(ethylene oxide) (PEO) to form amphiphilic block copolymers. These copolymers were self-assembled to form nanoparticles in aqueous solution. Cleavage of the linker end-caps were triggered by a thiol reducing agent, UV light, H 2 O 2 , and combinations of these stimuli, resulting in nanoparticle disintegration. Low stimuli concentrations were effective in rapidly disrupting the nanoparticles. Nile red, doxorubin, and curcumin were encapsulated into the nanoparticles and were selectively released upon application of the appropriate stimulus. The ability to tune the stimuli-responsiveness simply by changing the linker end-cap makes this new platform highly attractive for applications in drug delivery.

  5. 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.

  6. Synthesis and shape control of uniform polymer microparticles by tailored adsorption of poly(ethylene oxide)-b-Poly(ε-caprolactone) copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Acter, Shahinur; Cho, Jang Woo; Kim, Jeong Won; Byun, Aram; Park, Kyoung Ho; Kim, Jin Woong [Hanyang University, Ahnsan (Korea, Republic of)

    2015-05-15

    This paper introduces a straightforward and robust polymerization method for the synthesis of uniform polymer microparticles having controlled surface chemistry as well as tailored particle shapes. Uniform polystyrene (PS) microparticles are produced by dispersion polymerization, in which amphiphilic poly(ethylene oxide)-b-poly(ε-caprolactone) (PEO-b-PCL) copolymers anchor on to the growing polymer particles and stabilize them by steric repulsion. We have observed that, when PEO-b-PCL copolymers are incorporated at the proper concentration range, the total number of particles remains unchanged after the formation of primary particles, which is essential for maintaining size uniformity. Otherwise, nonuniform PS microparticles are produced mainly as a result of the coagulation or secondary formation of particles. To show the diversity of our particle synthesis technology, shape-controlled microparticles, such as dimples and Janus particles, are also produced by using temperature-mediated swelling and phase separation. Finally, we show that PEO-b-PCL copolymers play a key role in regulating the surface wettability of the seed particles, thereby facilitating the formation of anisotropic microparticles.

  7. 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.

  8. 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)

    de Kroon, A.I.P.M.; Killian, J.A.; de Gier, J.; de Kruijff, B.

    1991-01-01

    Deuterium nuclear magnetic resonance ( 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 β-position of the serine moiety ([2- 2 H]DOPS) or at the 11-position of the acyl chains ([11,11- 2 H 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- 2 H]DOPS and [11,11- 2 H 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) 100 , which were included for reasons of comparison, reveal increased Δv q values. When the peptide-lipid titrations are carried out without applying a freeze-thaw procedure to achieve full equilibration, two-component 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. 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

  9. Tailoring nanostructure and bioactivity of 3D printable hydrogels with self-assemble Peptides Amphiphile (PA) for promoting bile duct formation.

    Science.gov (United States)

    Yan, Ming; Lewis, Phillip L; Shah, Ramille N

    2018-05-31

    3D-printing has expanded our ability to produce reproducible and more complex scaffold architectures for tissue engineering applications. In order to enhance the biological response within these 3D printed scaffolds incorporating nanostructural features and/or specific biological signaling may be an effective means to optimize tissue regeneration. Peptides Amphiphiles (PAs) are a versatile supramolecular biomaterial with tailorable nanostructural and biochemical features. PAs are widely used in tissue engineering applications such as angiogenesis, neurogenesis, and bone regeneration. Thus, the addition of PAs is a potential solution that can greatly expand the utility of 3D bio-printing hydrogels in the field of regenerative medicine. In this paper, we firstly developed a 3D printable thiolated-gelatin bioink supplemented with PAs to tailor the bioactivity and nanostructure which allows for the incorporation of cells. The bioink can be printed at 4 °C and stabilized to last a long time (>1 month) in culture at 37 °C by via a dual secondary cross-linking strategy using calcium ions and homobifunctional maleiminde-poly (ethylene glycol). Rheological properties of inks were characterized and were suitable for printing multi-layered structures. We additionally demonstrated enhanced functionality of ink formulations by utilizing a laminin-mimetic IKVAV-based PA system within a 3D-printable ink containing cholangiocytes. Viability and functional staining showed that the IKVAV PA nanofibers stimulated cholangioctyes to form functional tubular structures, which was not observed in other ink formulations. . © 2018 IOP Publishing Ltd.

  10. 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

  11. Role of nano-range amphiphilic polymers in seed quality enhancement of soybean and imidacloprid retention capacity on seed coatings.

    Science.gov (United States)

    Adak, Totan; Kumar, Jitendra; Shakil, Najam A; Pandey, Sushil

    2016-10-01

    Nano-size and wide-range solubility of amphiphilic polymers (having both hydrophilic and hydrophobic blocks) can improve uniformity in seed coatings. An investigation was carried out to assess the positive effect of amphiphilic polymers over hydrophilic or hydrophobic polymers as seed coating agents and pesticide carriers. Amphiphilic polymers with 127.5-354 nm micelle size were synthesized in the laboratory using polyethylene glycols and aliphatic di-acids. After 6 months of storage, germination of uncoated soybean seeds decreased drastically from 97.80 to 81.55%, while polymer-coated seeds showed 89.44-95.92% germination. Similarly, vigour index-1 was reduced from 3841.10 to 2813.06 for control seeds but ranged from 3375.59 to 3844.60 for polymer-coated seeds after 6 months. The developed imidacloprid formulations retained more pesticide on soybean seed coatings than did a commercial formulation (Gaucho(®) 600 FS). The time taken for 50% release of imidacloprid from seed coatings in water was 7.12-9.11 h for the developed formulations and 0.41 h for the commercial formulation. Nano-range amphiphilic polymers can be used to protect soybean seeds from ageing. Formulations as seed treatments may produce improved and sustained efficacy with minimum environmental contamination. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  12. Recovery and redispersion of gold nanoparticles using the self-assembly of a pH sensitive zwitterionic amphiphile.

    Science.gov (United States)

    Morita-Imura, Clara; Imura, Yoshiro; Kawai, Takeshi; Shindo, Hitoshi

    2014-11-04

    The pH-responsive self-assembly of zwitterionic amphiphile C16CA was expanded to the recovery of gold (Au) nanoparticles for environmentally friendly chemistry applications. Multilayered lamellae at pH ∼ 4 were successfully incorporated into nanoparticles by dispersion. Redispersion of nanoparticles was achieved under basic conditions by the transition of self-assembly.

  13. 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.

  14. 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

  15. Adamantane-based amphiphiles (ADAs) for membrane protein study: importance of a detergent hydrophobic group in membrane protein solubilisation.

    Science.gov (United States)

    Chae, Pil Seok; Bae, Hyoung Eun; Das, Manabendra

    2014-10-21

    We prepared adamantane-containing amphiphiles and evaluated them using a large membrane protein complex in terms of protein solubilisation and stabilization efficacy. These agents were superior to conventional detergents, especially in terms of the membrane protein solubilisation efficiency, implying a new detergent structure-property relationship.

  16. A Water-Soluble Cyclotriveratrylene-Based Supra-amphiphile: Synthesis, pH-Responsive Self-Assembly in Water, and Its Application in Controlled Drug Release.

    Science.gov (United States)

    Xia, Danyu; Li, Yang; Jie, Kecheng; Shi, Bingbing; Yao, Yong

    2016-06-17

    A new water-soluble cyclotriveratrylene (WCTV) was designed and synthesized, and benzyldimethyldodecylammonium chloride (G) was chosen as the guest molecule to construct a supra-amphiphile by the host-guest interaction between WCTV and G in water, which is pH responsive. The supra-amphiphiles self-assembled into vesicles in water. When the pH of the solution was below 7.0, the supra-amphiphile disassociated, and the vesicles collapsed. Then, the pH-responsive self-assembly system was utilized for controlled drug release.

  17. Hydrophobic cotton textile surfaces using an amphiphilic graphene oxide (GO) coating

    International Nuclear Information System (INIS)

    Tissera, Nadeeka D.; Wijesena, Ruchira N.; Perera, J. Rangana; Nalin de Silva, K.M.; Amaratunge, Gehan A.J.

    2015-01-01

    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

  18. 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.

  19. Hydrophobic hydration of poly-N-isopropyl acrylamide: a matter of the mean energetic state of water

    Science.gov (United States)

    Bischofberger, I.; Calzolari, D. C. E.; de Los Rios, P.; Jelezarov, I.; Trappe, V.

    2014-03-01

    The enthalpically favoured hydration of hydrophobic entities, termed hydrophobic hydration, impacts the phase behaviour of numerous amphiphiles in water. Here, we show experimental evidence that hydrophobic hydration is strongly determined by the mean energetics of the aqueous medium. We investigate the aggregation and collapse of an amphiphilic polymer, poly-N-isopropyl acrylamide (PNiPAM), in aqueous solutions containing small amounts of alcohol and find that the thermodynamic characteristics defining the phase transitions of PNiPAM evolve relative to the solvent composition at which the excess mixing enthalpy of the water/alcohol mixtures becomes minimal. Such correlation between solvent energetics and solution thermodynamics extends to other mixtures containing neutral organic solutes that are considered as kosmotropes to induce a strengthening of the hydrogen bonded water network. This denotes the energetics of water as a key parameter controlling the phase behaviour of PNiPAM and identifies the excess mixing enthalpy of water/kosmotrope mixtures as a gauge of the kosmotropic effect on hydrophobic assemblies.

  20. pH-Sensitive Amphiphilic Block-Copolymers for Transport and Controlled Release of Oxygen

    KAUST Repository

    Patil, Yogesh Raghunath

    2017-05-31

    Saturated fluorocarbons, their derivatives and emulsions are capable of dissolving anomalously high amounts of oxygen and other gases. The mechanistic aspects of this remarkable effect remain to be explored experimentally. Here, the synthesis of a library of amphiphilic fluorous block-copolymers incorporating different fluorinated monomers is described, and the capacity of these copolymers for oxygen transport in water is systematically investigated. The structure of the fluorous monomer employed was found to have a profound effect on both the oxygen-carrying capacity and the gas release kinetics of the polymer emulsions. Furthermore, the release of O2 from the polymer dispersions could be triggered by changing the pH of the solution. This is the first example of a polymer-based system for controlled release of a non-polar, non-covalently entrapped respiratory gas.

  1. Two-dimensional crystallography of amphiphilic molecules at the air-water interface

    DEFF Research Database (Denmark)

    Jacquemain, D.; Grayer Wolf, S.; Leveiller, F.

    1992-01-01

    The advent of well-collimated, high-intensity synchrotron X-ray sources and the consequent development of surface-specific X-ray diffraction and fluorescence techniques have recently revolutionized the study of Langmuir monolayers at the air-liquid interface. These methods allowed for the first......, and review recent results obtained from them for Langmuir films. The methods have been successfully applied in the elucidation of the structure of crystalline aggregates of amphiphilic molecules such as alcohols, carboxylic acids and their salts, alpha-amino acids, and phospholipids at the water surface....... In addition, it became possible to monitor by diffraction the growth and dissolution of the crystalline self-aggregates as well as structural changes occurring by phase transitions. Furthermore, the surface X-ray methods shed new light on the structure of the underlying ionic layer of attached solvent...

  2. pH-Sensitive Amphiphilic Block-Copolymers for Transport and Controlled Release of Oxygen

    KAUST Repository

    Patil, Yogesh Raghunath; Almahdali, Sarah; Vu, Khanh B.; Zapsas, Georgios; Hadjichristidis, Nikolaos; Rodionov, Valentin

    2017-01-01

    Saturated fluorocarbons, their derivatives and emulsions are capable of dissolving anomalously high amounts of oxygen and other gases. The mechanistic aspects of this remarkable effect remain to be explored experimentally. Here, the synthesis of a library of amphiphilic fluorous block-copolymers incorporating different fluorinated monomers is described, and the capacity of these copolymers for oxygen transport in water is systematically investigated. The structure of the fluorous monomer employed was found to have a profound effect on both the oxygen-carrying capacity and the gas release kinetics of the polymer emulsions. Furthermore, the release of O2 from the polymer dispersions could be triggered by changing the pH of the solution. This is the first example of a polymer-based system for controlled release of a non-polar, non-covalently entrapped respiratory gas.

  3. 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.

  4. 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...

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

    Science.gov (United States)

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

    2013-10-03

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

  6. Electrophysiological Assessment of a Peptide Amphiphile Nanofiber Nerve Graft for Facial Nerve Repair.

    Science.gov (United States)

    Greene, Jacqueline J; McClendon, Mark T; Stephanopoulos, Nicholas; Álvarez, Zaida; Stupp, Samuel I; Richter, Claus-Peter

    2018-04-27

    Facial nerve injury can cause severe long-term physical and psychological morbidity. There are limited repair options for an acutely transected facial nerve not amenable to primary neurorrhaphy. We hypothesize that a peptide amphiphile nanofiber neurograft may provide the nanostructure necessary to guide organized neural regeneration. Five experimental groups were compared, animals with 1) an intact nerve, 2) following resection of a nerve segment, and following resection and immediate repair with either a 3) autograft (using the resected nerve segment), 4) neurograft, or 5) empty conduit. The buccal branch of the rat facial nerve was directly stimulated with charge balanced biphasic electrical current pulses at different current amplitudes while nerve compound action potentials (nCAPs) and electromygraphic (EMG) responses were recorded. After 8 weeks, the proximal buccal branch was surgically re-exposed and electrically evoked nCAPs were recorded for groups 1-5. As expected, the intact nerves required significantly lower current amplitudes to evoke an nCAP than those repaired with the neurograft and autograft nerves. For other electrophysiologic parameters such as latency and maximum nCAP, there was no significant difference between the intact, autograft and neurograft groups. The resected group had variable responses to electrical stimulation, and the empty tube group was electrically silent. Immunohistochemical analysis and TEM confirmed myelinated neural regeneration. This study demonstrates that the neuroregenerative capability of peptide amphiphile nanofiber neurografts is similar to the current clinical gold standard method of repair and holds potential as an off-the-shelf solution for facial reanimation and potentially peripheral nerve repair. This article is protected by copyright. All rights reserved.

  7. Adsorption, folding, and packing of an amphiphilic peptide at the air/water interface.

    Science.gov (United States)

    Engin, Ozge; Sayar, Mehmet

    2012-02-23

    Peptide oligomers play an essential role as model compounds for identifying key motifs in protein structure formation and protein aggregation. Here, we present our results, based on extensive molecular dynamics simulations, on adsorption, folding, and packing within a surface monolayer of an amphiphilic peptide at the air/water interface. Experimental results suggest that these molecules spontaneously form ordered monolayers at the interface, adopting a β-hairpin-like structure within the surface layer. Our results reveal that the β-hairpin structure can be observed both in bulk and at the air/water interface. However, the presence of an interface leads to ideal partitioning of the hydrophobic and hydrophilic residues, and therefore reduces the conformational space for the molecule and increases the stability of the hairpin structure. We obtained the adsorption free energy of a single β-hairpin at the air/water interface, and analyzed the enthalpic and entropic contributions. The adsorption process is favored by two main factors: (1) Free-energy reduction due to desolvation of the hydrophobic side chains of the peptide and release of the water molecules which form a cage around these hydrophobic groups in bulk water. (2) Reduction of the total air/water contact area at the interface upon adsorption of the peptide amphiphile. By performing mutations on the original molecule, we demonstrated the relative role of key design features of the peptide. Finally, by analyzing the potential of mean force among two peptides at the interface, we investigated possible packing mechanisms for these molecules within the surface monolayer. © 2012 American Chemical Society

  8. Self assembly of amphiphilic C60 fullerene derivatives into nanoscale supramolecular structures

    Directory of Open Access Journals (Sweden)

    Casscells S Ward

    2007-08-01

    Full Text Available Abstract Background The amphiphilic fullerene monomer (AF-1 consists of a "buckyball" cage to which a Newkome-like dendrimer unit and five lipophilic C12 chains positioned octahedrally to the dendrimer unit are attached. In this study, we report a novel fullerene-based liposome termed 'buckysome' that is water soluble and forms stable spherical nanometer sized vesicles. Cryogenic electron microscopy (Cryo-EM, transmission electron microscopy (TEM, and dynamic light scattering (DLS studies were used to characterize the different supra-molecular structures readily formed from the fullerene monomers under varying pH, aqueous solvents, and preparative conditions. Results Electron microscopy results indicate the formation of bilayer membranes with a width of ~6.5 nm, consistent with previously reported molecular dynamics simulations. Cryo-EM indicates the formation of large (400 nm diameter multilamellar, liposome-like vesicles and unilamellar vesicles in the size range of 50–150 nm diameter. In addition, complex networks of cylindrical, tube-like aggregates with varying lengths and packing densities were observed. Under controlled experimental conditions, high concentrations of spherical vesicles could be formed. In vitro results suggest that these supra-molecular structures impose little to no toxicity. Cytotoxicity of 10–200 μM buckysomes were assessed in various cell lines. Ongoing studies are aimed at understanding cellular internalization of these nanoparticle aggregates. Conclusion In this current study, we have designed a core platform based on a novel amphiphilic fullerene nanostructure, which readily assembles into supra-molecular structures. This delivery vector might provide promising features such as ease of preparation, long-term stability and controlled release.

  9. Yolk–shell Fe3O4@SiO2@PMO: amphiphilic magnetic nanocomposites as an adsorbent and a catalyst with high efficiency and recyclability

    KAUST Repository

    Dai, Jinyu; Zou, Houbing; Wang, Runwei; Wang, Yu; Shi, Zhiqiang; Qiu, Shilun

    2017-01-01

    This study describes the preparation of a multifunctional adsorptive catalyst by the incorporation of ligand groups within the channels of magnetic amphiphilic nanocomposites and attached with Pd nanoparticles. It was clearly demonstrated that Pd2

  10. In Situ Mapping of the Molecular Arrangement of Amphiphilic Dye Molecules at the TiO 2 Surface of Dye-Sensitized Solar Cells

    KAUST Repository

    Voï tchovsky, Kislon; Ashari-Astani, Negar; Tavernelli, Ivano; Té treault, Nicolas; Rothlisberger, Ursula; Stellacci, Francesco; Grä tzel, Michael; Harms, Hauke A.

    2015-01-01

    © 2015 American Chemical Society. Amphiphilic sensitizers are central to the function of dye-sensitized solar cells. It is known that the cell's performance depends on the molecular arrangement and the density of the dye on the semiconductor surface

  11. Poly(ethylene oxide monomethyl ether)- block-poly(propylene succinate) Nanoparticles: Synthesis and Characterization, Enzymatic and Cellular Degradation, Micellar Solubilization of Paclitaxel, and in Vitro and in Vivo Evaluation.

    Science.gov (United States)

    Jäger, Alessandro; Jäger, Eliézer; Syrová, Zdeňka; Mazel, Tomas; Kováčik, Lubomír; Raška, Ivan; Höcherl, Anita; Kučka, Jan; Konefal, Rafal; Humajova, Jana; Poučková, Pavla; Štěpánek, Petr; Hrubý, Martin

    2018-04-11

    Polyester-based nanostructures are widely studied as drug-delivery systems due to their biocompatibility and biodegradability. They are already used in the clinic. In this work, we describe a new and simple biodegradable and biocompatible system as the Food and Drug Administration approved polyesters (poly-ε-caprolactone, polylactic acid, and poly(lactic- co-glycolic acid)) for the delivery of the anticancer drug paclitaxel (PTX) as a model drug. A hydrophobic polyester, poly(propylene succinate) (PPS), was prepared from a nontoxic alcohol (propylene glycol) and monomer from the Krebs's cycle (succinic acid) in two steps via esterification and melt polycondensation. Furthermore, their amphiphilic block copolyester, poly(ethylene oxide monomethyl ether)- block-poly(propylene succinate) (mPEO- b-PPS), was prepared by three steps via esterification followed by melt polycondensation and the addition of mPEO to the PPS macromolecules. Analysis of the in vitro cellular behavior of the prepared nanoparticle carriers (NPs) (enzymatic degradation, uptake, localization, and fluorescence resonance energy-transfer pair degradation studies) was performed by fluorescence studies. PTX was loaded to the NPs of variable sizes (30, 70, and 150 nm), and their in vitro release was evaluated in different cell models and compared with commercial PTX formulations. The mPEO- b-PPS copolymer analysis displays glass transition temperature hydrolysis during transport in bloodstream, and simultaneous enzymatic degradability after uptake into the cells. The detailed cytotoxicity in vitro and in vivo tumor efficacy studies have shown the superior efficacy of the NPs compared with PTX and PTX commercial formulations.

  12. Thermoresponsive Interplay of Water Insoluble Poly(2-alkyl-2-oxazolines Composition and Supramolecular Host–Guest Interactions

    Directory of Open Access Journals (Sweden)

    Victor R. de la Rosa

    2015-04-01

    Full Text Available A series of water insoluble poly[(2-ethyl-2-oxazoline-ran-(2-nonyl-2-oxazoline] amphiphilic copolymers was synthesized and their solubility properties in the presence of different supramolecular host molecules were investigated. The resulting polymer-cavitand assemblies exhibited a thermoresponsive behavior that could be modulated by variation of the copolymer composition and length. Interestingly, the large number of hydrophobic nonyl units across the polymer chain induced the formation of kinetically-trapped nanoparticles in solution. These nanoparticles further agglomerate into larger aggregates at a temperature that is dependent on the polymer composition and the cavitand type and concentration. The present research expands the understanding on the supramolecular interactions between water insoluble copolymers and supramolecular host molecules.

  13. Self-assembly behavior of well-defined polymethylene-block-poly(ethylene glycol) copolymers in aqueous solution

    KAUST Repository

    Alkayal, Nazeeha

    2016-09-22

    A series of well-defined amphiphilic polymethylene-b-poly(ethylene glycol) (PM-b-PEG) diblock copolymers, with different hydrophobic chain length, were synthesized by combining Diels-Alder reaction with polyhomologation. The successful synthetic procedure was confirmed by size-exclusion chromatography (SEC) and 1H NMR spectroscopy. These block copolymers self-assembled into spherical micelles in aqueous solutions and exhibit low critical micelle concentration (CMC) of 2–4 mg/mL, as determined by fluorescence spectroscopy using pyrene as a probe. Measurements of the micelle hydrodynamic diameters, performed by dynamic light scattering (DLS), cryo-transmission electron microscopy (cryo-TEM) and atomic force microscopy (AFM), revealed a direct dependence of the micelle size from the polymethylene block length.

  14. 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

    Polymeric nanoparticles are widely investigated as drug delivery systems for oral administration. However, the hydrophobic nature of many polymers hampers effective loading of the particles with hydrophilic macromolecules such as insulin. Thus, the aim of this work was to improve the loading...... 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...... efficiencies (90% as compared to 24% in the absence of lipids). Importantly, the insulin loading capacity was increased up to 20% by using the lipid–insulin complexes. The results further showed that a main fraction of the lipid was incorporated into the nanoparticles and remained associated to the polymer...

  15. Sulfonated amphiphilic block copolymers : synthesis, self-assembly in water, and application as stabilizer in emulsion polymerization

    Science.gov (United States)

    Jiguang Zhang; Matthew R. Dubay; Carl J. Houtman; Steven J. Severtson

    2009-01-01

    Described is the synthesis of diblock copolymers generated via sequential atom transfer radical polymerization (ATRP) of poly(n-butyl acrylate) (PnBA) followed by chain augmentation with either sulfonated poly(2-hydroxyethyl methacrylate) (PHEMA) or poly(2-hydroxyethyl acrylate) (PHEA) blocks. ATRP of PHEMA or PHEA from PnBA macroinitiator was conducted in acetone/...

  16. Ga(III) chelates of amphiphilic DOTA-based ligands: synthetic route and in vitro and in vivo studies

    International Nuclear Information System (INIS)

    Fontes, Andre; Prata, M. Isabel M.; Geraldes, Carlos F.G.C.; Andre, Joao P.

    2011-01-01

    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 α-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 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.

  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. Ion-specific weak adsorption of salts and water/octanol transfer free energy of a model amphiphilic hexapeptide.

    Science.gov (United States)

    Déjugnat, Christophe; Dufrêche, Jean-François; Zemb, Thomas

    2011-04-21

    An amphiphilic hexapeptide has been used as a model to quantify how specific ion effects induced by addition of four salts tune the hydrophilic/hydrophobic balance and induce temperature-dependant coacervate formation from aqueous solution. The hexapeptide chosen is present as a dimer with low transfer energy from water to octanol. Taking sodium chloride as the reference state in the Hofmeister scale, we identify water activity effects and therefore measure the free energy of transfer from water to octanol and separately the free energy associated to the adsorption of chaotropic ions or the desorption of kosmotropic ions for the same amphiphilic peptide. These effects have the same order of magnitude: therefore, both energies of solvation as well as transfer into octanol strongly depend on the nature of the electrolytes used to formulate any buffer. Model peptides could be used on separation processes based on criteria linked to "Hofmeister" but different from volume and valency.

  19. 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

  20. One-Pot Synthesis of (+-Nootkatone via Dark Singlet Oxygenation of Valencene: The Triple Role of the Amphiphilic Molybdate Catalyst

    Directory of Open Access Journals (Sweden)

    Bing Hong

    2016-11-01

    Full Text Available Efficient one-pot catalytic synthesis of (+-nootkatone was performed from (+-valencene using only hydrogen peroxide and amphiphilic molybdate ions. The process required no solvent and proceeded in three cascade reactions: (i singlet oxygenation of valencene according to the ene reaction; (ii Schenck rearrangement of one hydroperoxide into the secondary β-hydroperoxide; and (iii dehydration of the hydroperoxide into the desired (+-nootkatone. The solvent effect on the hydroperoxide rearrangement is herein discussed. The amphiphilic dimethyldioctyl ammonium molybdate, which is also a balanced surfactant, played a triple role in this process, as molybdate ions catalyzed at both Step 1 and Step 3 and it allowed the rapid formation of a three-phase microemulsion system that highly facilitates product recovery. Preparative synthesis of the high added value (+-nootkatone was thus performed at room temperature with an isolated yield of 46.5%. This is also the first example of a conversion of allylic hydroperoxides into ketones catalyzed by molybdate ions.

  1. Highly ordered self-assembly of one-dimensional nanoparticles in amphiphilic molecular systems

    International Nuclear Information System (INIS)

    Kim, Tae Hwan

    2009-02-01

    Two kinds of one-dimensional (1D) nanoparticles, stable rod-like nanoparticles with highly controlled surface charge density (cROD) and non-covalently functionalized isolated single wall carbon nanotubes (p-SWNT) that were readily redispersible in water, have been developed. Using these 1D nanoparticles, various highly ordered superstructures of 1D nanoparticles by molecular self-assembling based on electrostatic interaction in amphiphilic molecular systems (two different cationic liposome systems) have been investigated. To our knowledge, this is the first demonstration of highly ordered self-assembly of 1D nanoparticles based on electrostatic interaction between 1D nanoparticles and amphiphilic molecules. The cRODs have been developed by free radical polymerization of a mixture of polymerizable cationic surfactant, cetyltrimethylammonium 4-vinylbenzoate (CTVB), and hydrotropic salt sodium 4-styrenesulfonate (NaSS) in aqueous solution. The surface charge of the cROD was controlled by varying the NaSS concentration during the polymerization process and the charge variation was interpreted in terms of the overcharging effect in colloidal systems. The small angle neutron scattering (SANS) measurements showed that the diameter of cROD is constant at 4 nm and the particle length ranges from 20 nm to 85 nm, depending on the NaSS concentration. The cRODs are longest when the NaSS concentration is 5 mol % which corresponds to the charge inversion or neutral point. The SANS and zeta potential measurements showed that the Coulomb interactions between the particles are strongly dependent on the NaSS concentration and the zeta potential of the cRODs changes from positive to negative (+ 12.8 mV ∼ - 44.2 mV) as the concentration of NaSS increases from 0 mol % to 40 mol %. As the NaSS concentration is further increased, the zeta potential is saturated at approximately - 50 mV. The p-SWNTs have been developed by 1) dispersing single wall carbon nanotubes (SWNTs) in water using

  2. Synthesis of Fluorinated Amphiphilic Block Copolymers Based on PEGMA, HEMA, and MMA via ATRP and CuAAC Click Chemistry

    OpenAIRE

    Erol, Fatime Eren; Sinirlioglu, Deniz; Cosgun, Sedat; Muftuoglu, Ali Ekrem

    2014-01-01

    Synthesis of fluorinated amphiphilic block copolymers via atom transfer radical polymerization (ATRP) and Cu(I) catalyzed Huisgen 1,3-dipolar cycloaddition (CuAAC) was demonstrated. First, a PEGMA and MMA based block copolymer carrying multiple side-chain acetylene moieties on the hydrophobic segment for postfunctionalization was carried out. This involves the synthesis of a series of P(HEMA-co-MMA) random copolymers to be employed as macroinitiators in the controlled synthesis of P(HEMA-co-M...

  3. Multiple cationic amphiphiles induce a Niemann-Pick C phenotype and inhibit Ebola virus entry and infection.

    Directory of Open Access Journals (Sweden)

    Charles J Shoemaker

    Full Text Available Ebola virus (EBOV is an enveloped RNA virus that causes hemorrhagic fever in humans and non-human primates. Infection requires internalization from the cell surface and trafficking to a late endocytic compartment, where viral fusion occurs, providing a conduit for the viral genome to enter the cytoplasm and initiate replication. In a concurrent study, we identified clomiphene as a potent inhibitor of EBOV entry. Here, we screened eleven inhibitors that target the same biosynthetic pathway as clomiphene. From this screen we identified six compounds, including U18666A, that block EBOV infection (IC(50 1.6 to 8.0 µM at a late stage of entry. Intriguingly, all six are cationic amphiphiles that share additional chemical features. U18666A induces phenotypes, including cholesterol accumulation in endosomes, associated with defects in Niemann-Pick C1 protein (NPC1, a late endosomal and lysosomal protein required for EBOV entry. We tested and found that all six EBOV entry inhibitors from our screen induced cholesterol accumulation. We further showed that higher concentrations of cationic amphiphiles are required to inhibit EBOV entry into cells that overexpress NPC1 than parental cells, supporting the contention that they inhibit EBOV entry in an NPC1-dependent manner. A previously reported inhibitor, compound 3.47, inhibits EBOV entry by blocking binding of the EBOV glycoprotein to NPC1. None of the cationic amphiphiles tested had this effect. Hence, multiple cationic amphiphiles (including several FDA approved agents inhibit EBOV entry in an NPC1-dependent fashion, but by a mechanism distinct from that of compound 3.47. Our findings suggest that there are minimally two ways of perturbing NPC1-dependent pathways that can block EBOV entry, increasing the attractiveness of NPC1 as an anti-filoviral therapeutic target.

  4. 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.

  5. One-Pot Synthesis of (+)-Nootkatone via Dark Singlet Oxygenation of Valencene: The Triple Role of the Amphiphilic Molybdate Catalyst

    OpenAIRE

    Bing Hong; Raphaël Lebeuf; Stéphanie Delbaere; Paul L. Alsters; Véronique Nardello-Rataj

    2016-01-01

    Efficient one-pot catalytic synthesis of (+)-nootkatone was performed from (+)-valencene using only hydrogen peroxide and amphiphilic molybdate ions. The process required no solvent and proceeded in three cascade reactions: (i) singlet oxygenation of valencene according to the ene reaction; (ii) Schenck rearrangement of one hydroperoxide into the secondary β-hydroperoxide; and (iii) dehydration of the hydroperoxide into the desired (+)-nootkatone. The solvent effect on the hydroperoxide rearr...

  6. New amphiphilic glycopolypeptide conjugate capable of self-assembly in water into reduction-sensitive micelles for triggered drug release

    International Nuclear Information System (INIS)

    Yang, Hui-Kang; Zhang, Li-Ming

    2014-01-01

    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

  7. 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

  8. Tacticities study of high poly-α-olefins, from poly-1-hexene to poly-1-octadecene, obtained with metallocenes catalysts

    International Nuclear Information System (INIS)

    Silva, Luciano F. da; Galland, Griselda B.

    2003-01-01

    High poly-α-olefins such as poly-1-hexene, poly-1-octene, poly-1-decene, poly-1-dodecene, poly-1-tetradecene, poly-1-hexadecene and poly-1-octadecene were obtained with the homogeneous iso specific catalyst rac-Et[Ind]ZrCl 2 /MAO and with the homogeneous syndiospecific catalyst Me 2 C[Cp(9-Flu)]ZrCl 2 /MAO at the polymerization temperatures of 0 deg C, 30 deg C and 60 deg C. The polymers were analyzed by 13 C NMR to study the influence of the α - olefins sizes, the catalysts type and the polymerization temperatures in their tacticities. The stereospecific control of both catalytic systems decreased with the increase of the reaction temperature and with the α-olefin size. (author)

  9. 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.

  10. Host-Guest Interaction between Corona[n]arene and Bisquaternary Ammonium Derivatives for Fabricating Supra-Amphiphile.

    Science.gov (United States)

    Zeng, Lingda; Guo, Qing-Hui; Feng, Yuanning; Xu, Jiang-Fei; Wei, Yuhan; Li, Zhibo; Wang, Mei-Xiang; Zhang, Xi

    2017-06-13

    The interactions between a host, water-soluble corona[n]arene (S6-CAP), and a series of guests, bisquaternary ammonium derivatives (CnDAs), in water, were investigated. The host and guest can form 1:1 host-guest complex. Their binding constants decrease as the alkyl length of CnDAs increases, which can be tunable ranging from 10 3 to 10 6 M -1 . The binding processes are mainly entropy-driven, while the enthalpy changes also play an important role in enhancing the host-guest interactions. In addition, a supra-amphiphile was fabricated with S6-CAP and a normal surfactant bearing bisquaternary ammonium (C4R). The S6-CAP·C4R complex forms micellar aggregates in water, and the system possesses better assembling activity and dilution stability than its building block C4R. This study enriches the families of supra-amphiphiles with a new architecture, and employing such a supra-amphiphile in biofunctional materials is highly anticipated.

  11. Novel functional materials from renewable lipids: Amphiphilic antimicrobial polymers and latent heat thermal energy storage

    Science.gov (United States)

    Floros, Michael Christopher

    Vegetable oils represent an ideal and renewable feedstock for the synthesis of a variety of functional materials. However, without financial incentive or unique applications motivating a switch, commercial products continue to be manufactured from petrochemical resources. Two different families of high value, functional materials synthesized from vegetable oils were studied. These materials demonstrate superior and unique performance to comparable petrochemical analogues currently on the market. In the first approach, 3 amphiphilic thermoplastic polytriazoles with differing lipophilic segment lengths were synthesized in a polymerization process without solvents or catalysts. Investigation of monomer structure influence on the resultant functional behaviour of these polymers found distinctive odd/even behaviour reliant on the number of carbon atoms in the monomers. Higher concentrations of triazole groups, due to shorter CH2 chains in the monomeric dialkynes, resulted in more brittle polymers, displaying higher tensile strengths but reduced elongation to break characteristics. These polymers had similar properties to commercial petroleum derived thermoplastics. One polymer demonstrated self-assembled surface microstructuring, and displayed hydrophobic properties. Antimicrobial efficacy of the polymers were tested by applying concentrated bacterial solutions to the surfaces, and near complete inhibition was demonstrated after 4 hours. Scanning electron microscope images of killed bacteria showed extensive membrane damage, consistent with the observed impact of other amphiphilic compounds in literature. These polytriazoles are suited for applications in medical devices and implants, where major concerns over antibiotic resistance are prevalent. In the second approach, a series of symmetric, saturated diester phase change materials (PCMs) were also synthesized with superior latent heat values compared to commercial petrochemical analogues. These diesters exhibit

  12. Poly(bisphenol A carbonate) - poly(dimethylsiloxane) multiblock copolymers

    NARCIS (Netherlands)

    Aert, van H.A.M.; Nelissen, L.N.I.H.; Lemstra, P.J.; Brunelle, D.J.

    2001-01-01

    A versatile technique for the synthesis of multiblock copolymers of polydimethylsiloxane (PDMS) and poly(bisphenol A carbonate) (PC) is described. Specific reaction of the phenol end groups of a,¿-bis(bisphenol A)-terminated PDMS with the activated end groups of

  13. Formation and Mechanism of Superhydrophobic/Hydrophobic Surfaces Made from Amphiphiles through Droplet-Mediated Evaporation-Induced Self-Assembly.

    Science.gov (United States)

    Dong, Fangyuan; Zhang, Mi; Tang, Wai-Wa; Wang, Yi

    2015-04-23

    Superhydrophobic/hydrophobic surfaces have attracted wide attention because of their broad applications in various regions, including coating, textile, packaging, electronic devices, and bioengineering. Many studies have been focused on the fabrication of superhydrophobic/hydrophobic surfaces using natural materials. In this paper, superhydrophobic/hydrophobic surfaces were formed by an amphiphilic natural protein, zein, using electrospinning. Water contact angle (WCA) and scanning electron microscopy (SEM) were used to characterize the hydrophobicity and surface morphology of the electrospun structures. The highest WCA of the zein electrospun surfaces could reach 155.5 ± 1.4°. To further understand the mechanism of superhydrophobic surface formation from amphiphiles using electrospinning, a synthetic amphiphilic polymer was selected, and also, a method similar to electrospinning, spray drying, was tried. The electrospun amphiphilic polymer surface showed a high hydrophobicity with a WCA of 141.4 ± 0.7°. WCA of the spray-dried zein surface could reach 125.3 ± 2.1°. The secondary structures of the zein in the electrospun film and cast-dried film were studied using ATR-FTIR, showing that α-helix to β-sheet transformation happened during the solvent evaporation in the cast drying process but not in the electrospinning process. A formation mechanism was proposed on the basis of the orientation of the amphiphiles during the solvent evaporation of different fabrication methods. The droplet-based or jet-based evaporation during electrospinning and spray drying led to the formation of the superhydrophobic/hydrophobic surface by the accumulation of the hydrophobic groups of the amphiphiles on the surface, while the surface-based evaporation during cast drying led to the formation of the hydrophilic surface by the accumulation of the hydrophilic groups of the amphiphiles on the surface.

  14. Preparation and Performance of Amphiphilic Random Copolymer Noncovalently Modified MWCNTs/Epoxy Composite

    Directory of Open Access Journals (Sweden)

    MA Qiang

    2016-09-01

    Full Text Available An amphiphilic random copolymer of polyglycidyl methacrylate-co-N-vinyl carbazole P(GMA-co-NVC was synthesized by free radical polymerization and was used to noncovalently modify multi-walled carbon nanotubes (MWCNTs. The obtained P(GMA-co-NVC/MWCNTs was mixed with epoxy resin and used to reinforce epoxy resin. Polymer modified carbon nanotubes/epoxy resin composites were prepared by a casting molding method. Tensile test, electrical resistivity test and differential scanning calorimeter(DSC analysis were used to study the effect of polymer modified carbon nanotubes on the mechanical, electrical, and thermal properties of epoxy resin. The results show that the epoxy composite reinforced with P(GMA-co-NVC/MWCNTs shows a remarkable enhancement in both tensile strength and elongation at break compared to either the pure epoxy or the pristine MWCNTs/epoxy composites. In addition, the electrical conductivity of epoxy is significantly improved and the volume resistivity decreases from 1014Ω·m to 106Ω·m with 0.25% mass fraction loading of P(GMA-co-NVC/MWCNTs. Moreover, glass transition temperature of the epoxy composite also increases from 144℃ to 149℃.

  15. Pyrene-Labeled Amphiphiles: Dynamic And Structural Probes Of Membranes And Lipoproteins

    Science.gov (United States)

    Pownall, Henry J.; Homan, Reynold; Massey, John B.

    1987-01-01

    Lipids and proteins are important functional and structural components of living organisms. Although proteins are frequently found as soluble components of plasma or the cell cytoplasm, many lipids are much less soluble and separate into complex assemblies that usually contain proteins. Cell membranes and plasma lipoproteins' are two important macro-molecular assemblies that contain both lipids and proteins. Cell membranes are composed of a variety of lipids and proteins that form an insoluble bilayer array that has relatively little curvature over distances of several nm. Plasma lipoproteins are different in that they are much smaller, water-soluble, and have highly curved surfaces. A model of a high density lipoprotein (HDL) is shown in Figure 1. This model (d - 10 nm) contains a surface of polar lipids and proteins that surrounds a small core of insoluble lipids, mostly triglycerides and cholesteryl esters. The low density (LDL) (d - 25 nm) and very low density (VLDL) (d 90 nm) lipoproteins have similar architectures, except the former has a cholesteryl ester core and the latter a core that is almost exclusively triglyceride (Figure 1). The surface proteins of HDL are amphiphilic and water soluble; the single protein of LDL is insoluble, whereas VLDL contains both soluble and insoluble proteins. The primary structures of all of these proteins are known.

  16. Amphiphilic polymeric micelles as the nanocarrier for peroral delivery of poorly soluble anticancer drugs.

    Science.gov (United States)

    Tian, Ye; Mao, Shirui

    2012-06-01

    Many amphiphilic copolymers have recently been synthesized as novel promising micellar carriers for the delivery of poorly water-soluble anticancer drugs. Studies on the formulation and oral delivery of such micelles have demonstrated their efficacy in enhancing drug uptake and absorption, and exhibit prolonged circulation time in vitro and in vivo. In this review, literature on hydrophobic modifications of several hydrophilic polymers, including polyethylene glycol, chitosan, hyaluronic acid, pluronic and tocopheryl polyethylene glycol succinate, is summarized. Parameters influencing the properties of polymeric micelles for oral chemotherapy are discussed and strategies to overcome main barriers for polymeric micelles peroral absorption are proposed. During the design of polymeric micelles for peroral chemotherapy, selecting or synthesizing copolymers with good compatibility with the drug is an effective strategy to increase drug loading and encapsulation efficiency. Stability of the micelles can be improved in different ways. It is recommended to take permeability, mucoadhesion, sustained release, and P-glycoprotein inhibition into consideration during copolymer preparation or to consider adding some excipients in the formulation. Furthermore, both the copolymer structure and drug loading methods should be controlled in order to get micelles with appropriate particle size for better absorption.

  17. Transition metal ions mediated tyrosine based short peptide amphiphile nanostructures inhibit bacterial growth.

    Science.gov (United States)

    Joshi, Khashti Ballabh; Singh, Ramesh; Mishra, Narendra Kumar; Kumar, Vikas; Vinayak, Vandana

    2018-05-17

    We report the design and synthesis of biocompatible small peptide based molecule for the controlled and targeted delivery of the encapsulated bioactive metal ions via transforming their internal nanostructures. Tyrosine based short peptide amphiphile (sPA) was synthesized which self-assembled into β-sheet like secondary structures. The self assembly of the designed sPA was modulated by using different bioactive transition metal ions which is confirmed by spectroscopic and microscopic techniques. These bioactive metal ions conjugated sPA hybrid structures are further used to develop antibacterial materials. It is due to the excellent antibacterial activity of zinc ions that the growth of clinically relevant bacteria such as E. Coli was inhibited in the presence of zinc-sPA conjugate. The bacterial test demonstrated that owing to high biocompatibility with bacterial cell, the designed sPA worked as metal ions delivery agent and therefore it can show great potential in locally addressing bacterial infections. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. A thermodynamic study of the amphiphilic phenothiazine drug thioridazine hydrochloride in water/ethanol solvent

    International Nuclear Information System (INIS)

    Cheema, Mohammad Arif; Barbosa, Silvia; Taboada, Pablo; Castro, Emilio; Siddiq, Mohammad; Mosquera, Victor

    2006-01-01

    The thermodynamic properties of aqueous solutions of the tricyclic antidepressant amphiphilic phenothiazine drug thioridazine hydrochloride in the temperature range 20-50 deg. C and in the presence of ethanol have been measured. The phenothiazine tranquillizing drugs have interesting association characteristics that derive from their rigid, tricyclic hydrophobic groups. Thioridazine hydrochloride is a drug used in treatment of mental illness that shows side effects. Therefore, it is interesting to study the change of its physico-chemical properties with temperature and with the surrounding environment to understand the action mechanism of the drug. Densities, conductivities, and surface tension were measured to obtain surface and bulk solution properties. Critical concentrations, cc, at different temperatures and in the presence of ethanol, and partition coefficients, K, have been calculated, the latter using an indirect method based in the pseudophase model with the help of apparent molar volume data. This method has the advantage that allows calculating the distribution coefficients at solubilizate concentrations below the saturation. Conductivity data show two critical concentrations. The second critical concentration is not clear by density data. The effect of the alcohol is to decrease the first critical concentration due to a decrease in headgroup repulsion. The molar apparent volumes at infinite dilution and in the aggregate in water and in presence of ethanol have been also obtained

  19. Diamond cubic phase of monoolein and water as an amphiphilic matrix for electrophoresis of oligonucleotides.

    Science.gov (United States)

    Carlsson, Nils; Winge, Ann-Sofie; Engström, Sven; Akerman, Björn

    2005-10-06

    We used a cubic liquid crystal formed by the nonionic monoglyceride monoolein and water as a porous matrix for the electrophoresis of oligonucleotides. The diamond cubic phase is thermodynamically stable when in contact with a water-rich phase, which we exploit to run the electrophoresis in the useful submarine mode. Oligonucleotides are separated according to size and secondary structure by migration through the space-filling aqueous nanometer pores of the regular liquid crystal, but the comparatively slow migration means the cubic phase will not be a replacement for the conventional DNA gels. However, our demonstration that the cubic phase can be used in submarine electrophoresis opens up the possibility for a new matrix for electrophoresis of amphiphilic molecules. From this perspective, the results on the oligonucleotides show that water-soluble particles of nanometer size, typical for the hydrophilic parts of membrane-bound proteins, may be a useful separation motif. A charged contamination in the commercial sample of monoolein, most likely oleic acid that arises from its hydrolysis, restricts useful buffer conditions to a pH below 5.6.

  20. Polypeptoids from N -Substituted Glycine N -Carboxyanhydrides: Hydrophilic, Hydrophobic, and Amphiphilic Polymers with Poisson Distribution

    KAUST Repository

    Fetsch, Corinna

    2011-09-13

    Preparation of defined and functional polymers has been one of the hottest topics in polymer science and drug delivery in the recent decade. Also, research on (bio)degradable polymers gains more and more interest, in particular at the interface of these two disciplines. However, in the majority of cases, combination of definition, functionality and degradability, is problematic. Here we present the preparation and characterization (MALDI-ToF MS, NMR, GPC) of nonionic hydrophilic, hydrophobic, and amphiphilic N-substituted polyglycines (polypeptoids), which are expected to be main-chain degradable and are able to disperse a hydrophobic model compound in aqueous media. Polymerization kinetics suggest that the polymerization is well controlled with strictly linear pseudo first-order kinetic plots to high monomer consumption. Moreover, molar mass distributions of products are Poisson-type and molar mass can be controlled by the monomer to initiator ratio. The presented polymer platform is nonionic, backbone degradable, and synthetically highly flexible and may therefore be valuable for a broad range of applications, in particular as a biomaterial. © 2011 American Chemical Society.

  1. Synthesis of Amphiphilic Hyperbranched AIE-active Fluorescent Organic Nanoparticles and Their Application in Biological Application.

    Science.gov (United States)

    Lv, Qiulan; Wang, Ke; Xu, Dazhuang; Liu, Meiying; Wan, Qing; Huang, Hongye; Liang, Shangdong; Zhang, Xiaoyong; Wei, Yen

    2016-02-01

    Aggregation-induced emission (AIE) dyes have recently attracted much attention for biomedical applications for their remarkable AIE properties. However, the hydrophobic nature of AIE dyes made them difficult to be dispersed in physiological solution and problematic for biomedical application directly. Great efforts have been made to overcome this problem, and different strategies for preparation of water dispersible AIE based nanoprobes had been explored previously. However, a facile and effective strategy is still highly desirable and of great importance for the biomedical applications of AIE dye based on nanoprobes. In this work, the fabrication of amphiphilic hyperbranched fluorescent organic nanoparticles with a core-shell structure based on an AIE dye [tetraphenylethene acrylate (TPE-O-E)] and a hyperbranched polyamino compound [polyethylene imine (PEI)] through Michael addition reaction is described for the first time. The AIE dye as well as the final product PEI-TPE-O-E was characterized in detail by a number of techniques. To test their biomedical application potential, the cell viability as well as cell imaging properties of the PEI-TPE-O-E was also examined. The results showed that the PEI-TPE-O-E organic nanoparticles presented high water dispersiblity, ultrabright fluroerescence, low cytotoxicity and excellent biocompatibility, making them promising for biological imaging and gene delivery applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Interaction of charged amphiphilic drugs with phosphatidylcholine vesicles studied by NMR

    International Nuclear Information System (INIS)

    Eriksson, L.E.G.

    1987-01-01

    Small unilamellar vesicles from egg phosphatidylcholine in NaCl solutions were exposed to some amphiphilic pharmaca. The aromatic drugs (chlorpromazine, dibucaine, tetracaine, imipramine and propranolol) were in their cationic form of the amines. By 1 H- and 31 P-NMR the membrane signals were observed. In particular, the N-methyl choline proton signals were followed upon drug addition. The intrinsic chemical shift difference (0.02 ppm) between the inner (upfield) and outer choline signals was influenced by the drug concentration. Packing properties of the lipid head groups and ring current shift probably contributed. At very high drug concentration, the vesicles are destroyed. A transformation into a micellar state with a high sample viscosity took place in a narrow concentration range of drug. The anion effects of Cl - were studied from the 35 Cl-NMR linewidth at 9.8 and 39.1 MHz. A continuous increase in the signal linewidth followed upon drug addition to the vesicles. Only chlorpromazine produced a broadening in the absence of vesicles (NaCl blank). The linewidth reflected a critical micelle concentration of this drug around 7 mM in 0.1 M NaCl. The 35 Cl-NMR experiments demonstrated the existence of an anionic counterion effect. This phenomenon should be accounted for when quantitatively analysing drug-membrane interactions in electrostatic terms. (Auth.)

  3. Luminescent Langmuir-Blodgett film of a new amphiphilic Eu3+ β-diketonate

    International Nuclear Information System (INIS)

    Gomes, Luciano F.; Oliveira, Kleber T. de; Neri, Claudio R.; Sousa Filho, Paulo C. de; Bianco, Marcos J. dal; Ramos, Ana P.; Zaniquelli, Maria E.D.; Serra, Osvaldo A.

    2008-01-01

    This work reports on the synthesis and characterization of the ligand 3-hexadecylpentane-2,4-dione (Hhdacac) and its Eu 3+ complexes Eu(hdacac) 6 .2H 2 O, Eu(hdacac) 6 .phen and Eu(hdacac) 6 .tta, where phen and tta denote 1,10-phenanthroline and thenoyltrifluoroacetone, respectively. These new compounds present long carbon chains and their expected miscibility into non-polar ambients is confirmed by the emission spectra of Eu(hdacac) 6 .tta in hexane. Moreover, the amphiphilic properties of Eu(hdacac) 6 complexes allow the obtainment of thin luminescent films by the Langmuir-Blodgett technique. In both cases (solids and films), the typical antenna effect of β-diketonates is observed. The alluring characteristics of these compounds raise great interest in many fields of Materials Science, like photo- and electro-luminescent materials (mainly thin 'organic' films), metal catalysts or probes in non-polar solutions, and Langmuir-Blodgett films of several compositions. For the characterization of these products, nuclear magnetic resonance spectroscopy ( 1 H NMR), thermogravimetric analysis, elementary analyses (C, H), scanning electron microscopy (energy dispersive X-ray spectroscopy), absorption (UV-vis/FT-IR) and photoluminescence spectroscopies were used

  4. Design and optimization of novel paclitaxel-loaded folate-conjugated amphiphilic cyclodextrin nanoparticles.

    Science.gov (United States)

    Erdoğar, Nazlı; Esendağlı, Güneş; Nielsen, Thorbjorn T; Şen, Murat; Öner, Levent; Bilensoy, Erem

    2016-07-25

    As nanomedicines are gaining momentum in the therapy of cancer, new biomaterials emerge as alternative platforms for the delivery of anticancer drugs with bioavailability problems. In this study, two novel amphiphilic cyclodextrins (FCD-1 and FCD-2) conjugated with folate group to enable active targeting to folate positive breast tumors were introduced. The objective of this study was to develop and characterize new folated-CD nanoparticles via 3(2) factorial design for optimal final parameters. Full physicochemical characterization studies were performed. Blank and paclitaxel loaded FCD-1 and FCD-2 nanoparticles remained within the range of 70-275nm and 125-185nm, respectively. Zeta potential values were neutral and -20mV for FCD-1 and FCD-2 nanoparticles, respectively. Drug release studies showed initial burst release followed by a longer sustained release. Blank nanoparticles had no cytotoxicity against L929 cells. T-47D and ZR-75-1 human breast cancer cells with different levels of folate receptor expression were used to assess anti-cancer efficacy. Through targeting the folate receptor, these nanoparticles were efficiently engulfed by the breast cancer cells. Additionally, breast cancer cells became more sensitive to cytotoxic and/or cytostatic effects of PCX delivered by FCD-1 and FCD-2. In conclusion, these novel folate-conjugated cyclodextrin nanoparticles can therefore be considered as promising alternative systems for safe and effective delivery of paclitaxel with a folate-dependent mechanism. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Force and time-dependent self-assembly, disruption and recovery of supramolecular peptide amphiphile nanofibers.

    Science.gov (United States)

    Dikecoglu, F Begum; Topal, Ahmet E; Ozkan, Alper D; Tekin, E Deniz; Tekinay, Ayse B; Guler, Mustafa O; Dana, Aykutlu

    2018-07-13

    Biological feedback mechanisms exert precise control over the initiation and termination of molecular self-assembly in response to environmental stimuli, while minimizing the formation and propagation of defects through self-repair processes. Peptide amphiphile (PA) molecules can self-assemble at physiological conditions to form supramolecular nanostructures that structurally and functionally resemble the nanofibrous proteins of the extracellular matrix, and their ability to reconfigure themselves in response to external stimuli is crucial for the design of intelligent biomaterials systems. Here, we investigated real-time self-assembly, deformation, and recovery of PA nanofibers in aqueous solution by using a force-stabilizing double-pass scanning atomic force microscopy imaging method to disrupt the self-assembled peptide nanofibers in a force-dependent manner. We demonstrate that nanofiber damage occurs at tip-sample interaction forces exceeding 1 nN, and the damaged fibers subsequently recover when the tip pressure is reduced. Nanofiber ends occasionally fail to reconnect following breakage and continue to grow as two individual nanofibers. Energy minimization calculations of nanofibers with increasing cross-sectional ellipticity (corresponding to varying levels of tip-induced fiber deformation) support our observations, with high-ellipticity nanofibers exhibiting lower stability compared to their non-deformed counterparts. Consequently, tip-mediated mechanical forces can provide an effective means of altering nanofiber integrity and visualizing the self-recovery of PA assemblies.

  6. Amphiphilic ligand exchange reaction-induced supercapacitor electrodes with high volumetric and scalable areal capacitances

    Science.gov (United States)

    Nam, Donghyeon; Heo, Yeongbeom; Cheong, Sanghyuk; Ko, Yongmin; Cho, Jinhan

    2018-05-01

    We introduce high-performance supercapacitor electrodes with ternary components prepared from consecutive amphiphilic ligand-exchange-based layer-by-layer (LbL) assembly among amine-functionalized multi-walled carbon nanotubes (NH2-MWCNTs) in alcohol, oleic acid-stabilized Fe3O4 nanoparticles (OA-Fe3O4 NPs) in toluene, and semiconducting polymers (PEDOT:PSS) in water. The periodic insertion of semiconducting polymers within the (OA-Fe3O4 NP/NH2-MWCNT)n multilayer-coated indium tin oxide (ITO) electrode enhanced the volumetric and areal capacitances up to 408 ± 4 F cm-3 and 8.79 ± 0.06 mF cm-2 at 5 mV s-1, respectively, allowing excellent cycling stability (98.8% of the initial capacitance after 5000 cycles) and good rate capability. These values were higher than those of the OA-Fe3O4 NP/NH2-MWCNT multilayered electrode without semiconducting polymer linkers (volumetric capacitance ∼241 ± 4 F cm-3 and areal capacitance ∼1.95 ± 0.03 mF cm-2) at the same scan rate. Furthermore, when the asymmetric supercapacitor cells (ASCs) were prepared using OA-Fe3O4 NP- and OA-MnO NP-based ternary component electrodes, they displayed high volumetric energy (0.36 mW h cm-3) and power densities (820 mW cm-3).

  7. Specific binding of large aggregates of amphiphilic molecules to the respective antibodies.

    Science.gov (United States)

    Nabok, Alexei; Tsargorodskaya, Anna; Holloway, Alan; Starodub, Nikolay F; Demchenko, Anna

    2007-07-31

    The Binding of nonylphenol to respective antibodies immobilized on solid substrates was studied with the methods of total internal reflection ellipsometry (TIRE) and QCM (quartz crystal microbalance) impedance spectroscopy. The binding reaction was proved to be highly specific having an association constant of KA=1.6x10(6) mol(-1) L and resulted in an increase in both the adsorbed layer thickness of 23 nm and the added mass of 18.3 microg/cm2 at saturation. The obtained responses of both TIRE and QCM methods are substantially higher than anticipated for the immune binding of single molecules of nonylphenol. The mechanism of binding of large aggregates of nonylphenol was suggested instead. Modeling of the micelle of amphiphilic nonylphenol molecules in aqueous solutions yielded a micelle size of about 38 nm. The mechanism of binding of large molecular aggregates to respective antibodies can be extended to other hydrophobic low-molecular-weight toxins such as T-2 mycotoxin. The formation of large molecular aggregates of nonylphenol and T-2 mycotoxin molecules on the surface was proved by the AFM study.

  8. Reversible photocontrol of molecular assemblies of metal complex containing azo-amphiphiles

    International Nuclear Information System (INIS)

    Einaga, Yasuaki; Mikami, Rie; Akitsu, Takashiro; Li, Guangming

    2005-01-01

    Photo-controllable molecular systems, [M(en) 2 ][Pt(en) 2 Cl 2 ](1) 4 (M 2+ =Pt 2+ , Pd 2+ and en=ethylenediamine), have been designed by the self-assembly of chloride-bridged platinum/palladium complexes and photochromic amphiphiles of the azobenzene derivative, 4-[4-(N-methyl-N-n-dodecylamino)phenylazo]benzene sulfonic acid (designated as compound 1). Reversible structural changes caused by cis-trans photoisomerization of azo groups in compound 1 were observed by alternating illumination of UV and visible light. Visible illumination resulted in the formation of the plate-like structures, whereas UV illumination resulted in fragmentation of the assembling structures. Reversible changes were observed in the electronic states of the chloride-bridged platinum/palladium complexes; the plate-like structures exhibited charge transfer absorption of chloride-bridged platinum complexes and delocalized Pt(II)/Pt(IV) states, while the fragments of the separated complexes exhibited no charge transfer bands. As a consequence, we have discovered that the reversible structural changes in this system could be controlled by photoillumination

  9. Amphiphilic semiconducting polymer as multifunctional nanocarrier for fluorescence/photoacoustic imaging guided chemo-photothermal therapy.

    Science.gov (United States)

    Jiang, Yuyan; Cui, Dong; Fang, Yuan; Zhen, Xu; Upputuri, Paul Kumar; Pramanik, Manojit; Ding, Dan; Pu, Kanyi

    2017-11-01

    Chemo-photothermal nanotheranostics has the advantage of synergistic therapeutic effect, providing opportunities for optimized cancer therapy. However, current chemo-photothermal nanotheranostic systems generally comprise more than three components, encountering the potential issues of unstable nanostructures and unexpected conflicts in optical and biophysical properties among different components. We herein synthesize an amphiphilic semiconducting polymer (PEG-PCB) and utilize it as a multifunctional nanocarrier to simplify chemo-photothermal nanotheranostics. PEG-PCB has a semiconducting backbone that not only serves as the diagnostic component for near-infrared (NIR) fluorescence and photoacoustic (PA) imaging, but also acts as the therapeutic agent for photothermal therapy. In addition, the hydrophobic backbone of PEG-PCB provides strong hydrophobic and π-π interactions with the aromatic anticancer drug such as doxorubicin for drug encapsulation and delivery. Such a trifunctionality of PEG-PCB eventually results in a greatly simplified nanotheranostic system with only two components but multimodal imaging and therapeutic capacities, permitting effective NIR fluorescence/PA imaging guided chemo-photothermal therapy of cancer in living mice. Our study thus provides a molecular engineering approach to integrate essential properties into one polymer for multimodal nanotheranostics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Polypeptoids from N -Substituted Glycine N -Carboxyanhydrides: Hydrophilic, Hydrophobic, and Amphiphilic Polymers with Poisson Distribution

    KAUST Repository

    Fetsch, Corinna; Grossmann, Arlett; Holz, Lisa; Nawroth, Jonas F.; Luxenhofer, Robert

    2011-01-01

    Preparation of defined and functional polymers has been one of the hottest topics in polymer science and drug delivery in the recent decade. Also, research on (bio)degradable polymers gains more and more interest, in particular at the interface of these two disciplines. However, in the majority of cases, combination of definition, functionality and degradability, is problematic. Here we present the preparation and characterization (MALDI-ToF MS, NMR, GPC) of nonionic hydrophilic, hydrophobic, and amphiphilic N-substituted polyglycines (polypeptoids), which are expected to be main-chain degradable and are able to disperse a hydrophobic model compound in aqueous media. Polymerization kinetics suggest that the polymerization is well controlled with strictly linear pseudo first-order kinetic plots to high monomer consumption. Moreover, molar mass distributions of products are Poisson-type and molar mass can be controlled by the monomer to initiator ratio. The presented polymer platform is nonionic, backbone degradable, and synthetically highly flexible and may therefore be valuable for a broad range of applications, in particular as a biomaterial. © 2011 American Chemical Society.

  11. A thermodynamic study of the amphiphilic phenothiazine drug thioridazine hydrochloride in water/ethanol solvent

    Energy Technology Data Exchange (ETDEWEB)

    Cheema, Mohammad Arif [Laboratorio de Fisica de Coloides y Polimeros, Grupo de Sistemas Complejos, Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782, Santiago de Compostela (Spain); Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Barbosa, Silvia [Laboratorio de Fisica de Coloides y Polimeros, Grupo de Sistemas Complejos, Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782, Santiago de Compostela (Spain)], E-mail: fmsilvia@usc.es; Taboada, Pablo [Laboratorio de Fisica de Coloides y Polimeros, Grupo de Sistemas Complejos, Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782, Santiago de Compostela (Spain); Castro, Emilio [Laboratorio de Fisica de Coloides y Polimeros, Grupo de Sistemas Complejos, Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782, Santiago de Compostela (Spain); Siddiq, Mohammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mosquera, Victor [Laboratorio de Fisica de Coloides y Polimeros, Grupo de Sistemas Complejos, Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782, Santiago de Compostela (Spain)], E-mail: fmvictor@usc.es

    2006-09-29

    The thermodynamic properties of aqueous solutions of the tricyclic antidepressant amphiphilic phenothiazine drug thioridazine hydrochloride in the temperature range 20-50 deg. C and in the presence of ethanol have been measured. The phenothiazine tranquillizing drugs have interesting association characteristics that derive from their rigid, tricyclic hydrophobic groups. Thioridazine hydrochloride is a drug used in treatment of mental illness that shows side effects. Therefore, it is interesting to study the change of its physico-chemical properties with temperature and with the surrounding environment to understand the action mechanism of the drug. Densities, conductivities, and surface tension were measured to obtain surface and bulk solution properties. Critical concentrations, cc, at different temperatures and in the presence of ethanol, and partition coefficients, K, have been calculated, the latter using an indirect method based in the pseudophase model with the help of apparent molar volume data. This method has the advantage that allows calculating the distribution coefficients at solubilizate concentrations below the saturation. Conductivity data show two critical concentrations. The second critical concentration is not clear by density data. The effect of the alcohol is to decrease the first critical concentration due to a decrease in headgroup repulsion. The molar apparent volumes at infinite dilution and in the aggregate in water and in presence of ethanol have been also obtained.

  12. Synthesis of a novel amphiphilic quaternized chitosan and its distribution in rats.

    Science.gov (United States)

    Liu, Xiaofei; Zeng, Anrong; Li, Lin; Yang, Fan; Wang, Qi; Sun, Zhong; Shen, Jun

    2011-01-01

    A novel amphiphilic chitosan derivative, N-[(2-hydroxy-3-N,N-dimethylhexadecyl ammonium)propyl]chitosan chloride (N-CQCs), was prepared with a degree of substitution (DS) of 15.58%. N-CQCs was positively charged and its zeta potential was +28.4 mV. The introduction of a long carbon chain with a quaternary ammonium salt group into the chitosan backbone enabled N-CQCs to be lipotropic and hydrophilic. According to the hypothesis of the hypocholesterolemic effect of N-CQCs, its organ distribution in rats was investigated 48 h after administration via gavage using fluorescein isothiocyanate labeling. N-CQCs showed lower cytotoxicity. The plasma half-life of N-CQCs in rats was 48 h and the plasma AUC0-48 h (P) was 371.70 μg/ml per h, suggesting that N-CQCs remained in body for a long time. The results also showed that the accumulation in adipose tissue and gastrointestinal tract was higher than in thymus, kidney, liver and spleen at 48 h after administration. It could be presumed that N-CQCs play an important part in the metabolic process of body fat. Adipose tissue and gastrointestinal tract were the probable interaction sites of N-CQCs and body fat.

  13. Bio-fabrication and physiological self-release of tissue equivalents using smart peptide amphiphile templates.

    Science.gov (United States)

    Gouveia, Ricardo M; Hamley, Ian W; Connon, Che J

    2015-10-01

    In this study we applied a smart biomaterial formed from a self-assembling, multi-functional synthetic peptide amphiphile (PA) to coat substrates with various surface chemistries. The combination of PA coating and alignment-inducing functionalised substrates provided a template to instruct human corneal stromal fibroblasts to adhere, become aligned and then bio-fabricate a highly-ordered, multi-layered, three-dimensional tissue by depositing an aligned, native-like extracellular matrix. The newly-formed corneal tissue equivalent was subsequently able to eliminate the adhesive properties of the template and govern its own complete release via the action of endogenous proteases. Tissues recovered through this method were structurally stable, easily handled, and carrier-free. Furthermore, topographical and mechanical analysis by atomic force microscopy showed that tissue equivalents formed on the alignment-inducing PA template had highly-ordered, compact collagen deposition, with a two-fold higher elastic modulus compared to the less compact tissues produced on the non-alignment template, the PA-coated glass. We suggest that this technology represents a new paradigm in tissue engineering and regenerative medicine, whereby all processes for the bio-fabrication and subsequent self-release of natural, bio-prosthetic human tissues depend solely on simple template-tissue feedback interactions.

  14. Cathepsin-Mediated Cleavage of Peptides from Peptide Amphiphiles Leads to Enhanced Intracellular Peptide Accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Acar, Handan [Institute; Department; Samaeekia, Ravand [Institute; Department; Schnorenberg, Mathew R. [Institute; Department; Medical; Sasmal, Dibyendu K. [Institute; Huang, Jun [Institute; Tirrell, Matthew V. [Institute; Institute; LaBelle, James L. [Department

    2017-08-24

    Peptides synthesized in the likeness of their native interaction domain(s) are natural choices to target protein protein interactions (PPIs) due to their fidelity of orthostatic contact points between binding partners. Despite therapeutic promise, intracellular delivery of biofunctional peptides at concentrations necessary for efficacy remains a formidable challenge. Peptide amphiphiles (PAs) provide a facile method of intracellular delivery and stabilization of bioactive peptides. PAs consisting of biofunctional peptide headgroups linked to hydrophobic alkyl lipid-like tails prevent peptide hydrolysis and proteolysis in circulation, and PA monomers are internalized via endocytosis. However, endocytotic sequestration and steric hindrance from the lipid tail are two major mechanisms that limit PA efficacy to target intracellular PPIs. To address these problems, we have constructed a PA platform consisting of cathepsin-B cleavable PAs in which a selective p53-based inhibitory peptide is cleaved from its lipid tail within endosomes, allowing for intracellular peptide accumulation and extracellular recycling of the lipid moiety. We monitor for cleavage and follow individual PA components in real time using a resonance energy transfer (FRET)-based tracking system. Using this platform, components in real time using a Forster we provide a better understanding and quantification of cellular internalization, trafficking, and endosomal cleavage of PAs and of the ultimate fates of each component.

  15. Balancing the intermolecular forces in peptide amphiphiles for controlling self-assembly transitions.

    Science.gov (United States)

    Buettner, C J; Wallace, A J; Ok, S; Manos, A A; Nicholl, M J; Ghosh, A; Tweedle, M F; Goldberger, J E

    2017-06-21

    While the influence of alkyl chain length and headgroup size on self-assembly behaviour has been well-established for simple surfactants, the rational control over the pH- and concentration-dependent self-assembly behaviour in stimuli responsive peptides remains an elusive goal. Here, we show that different amphiphilic peptides can have similar self-assembly phase diagrams, providing the relative strengths of the attractive and repulsive forces are balanced. Using palmitoyl-YYAAEEEEK(DO3A:Gd)-NH 2 and palmitoyl-YAAEEEEK(DO3A:Gd)-NH 2 as controls, we show that reducing hydrophobic attractive forces through fewer methylene groups in the alkyl chain will lead to a similar self-assembly phase diagram as increasing the electrostatic repulsive forces via the addition of a glutamic acid residue. These changes allow creation of self-assembled MRI vehicles with slightly different micelle and nanofiber diameters but with minimal changes in the spin-lattice T 1 relaxivity. These findings reveal a powerful strategy to design self-assembled vehicles with different sizes but with similar self-assembly profiles.

  16. Nonionic diethanolamide amphiphiles with isoprenoid-type hydrocarbon chains: thermotropic and lyotropic liquid crystalline phase behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Sagnella, Sharon M.; Conn, Charlotte E.; Krodkiewska, Irena; Drummond, Calum J. (CSIRO/MSE)

    2014-09-24

    The thermotropic and lyotropic liquid crystalline phase behaviour of a series of diethanolamide amphiphiles with isoprenoid-type hydrocarbon chains (geranoyl, H-farnesoyl, and phytanoyl) has been investigated. When neat, both H-farnesoyl and phytanoyl diethanolamide form a smectic liquid crystalline structure at sub-zero temperatures. In addition, all three diethanolamides exhibit a glass transition temperature at around -73 C. Geranoyl diethanolamide forms a lamellar crystalline phase with a lattice parameter of 17.4 {angstrom} following long term storage accompanied by the loss of the glass transition. In the presence of water, H-farnesoyl and phytanoyl diethanolamide form lyotropic liquid crystalline phases, whilst geranoyl diethanolamide forms an L{sub 2} phase. H-farnesoyl diethanolamide forms a fluid lamellar phase (L{sub {alpha}}) at room temperature and up to {approx} 40 C. Phytanoyl diethanolamide displays a rich mesomorphism forming the inverse diamond (Q{sub II}{sup D}) and gyroid (Q{sub II}{sup G}) bicontinuous cubic phases in addition to an L{sub {alpha}} phase.

  17. Single-component solid lipid nanocarriers prepared with ultra-long chain amphiphilic lipids

    DEFF Research Database (Denmark)

    Wei, Wei; Lu, Xiaonan; Wang, Zegao

    2017-01-01

    HYPOTHESIS: Synthetic sugar alcohol mono-behenates with high melting points, surface activity and resistance to enzymatic lipolysis, are expected to form stable single-component solid lipid nanocarriers (SC-SLNs). The preparation methods and the polar head group of the molecules should affect the......-probe sonication method had a micelle structure with fenofibrate incorporated into a lipid monolayer. This study provides an insight into the systematic development of novel amphiphilic lipids for solid lipid-based drug delivery system.......HYPOTHESIS: Synthetic sugar alcohol mono-behenates with high melting points, surface activity and resistance to enzymatic lipolysis, are expected to form stable single-component solid lipid nanocarriers (SC-SLNs). The preparation methods and the polar head group of the molecules should affect...... using the lipolysis model. The structure and drug distribution of the nanocarriers were studied using AFM and TEM. FINDINGS: Both the polar head group of the molecules and the preparation methods affect the particle size and size distribution. Nanocarriers prepared with sorbitol mono-behenates showed...

  18. Application of Super-Amphiphilic Silica-Nanogel Composites for Fast Removal of Water Pollutants

    Directory of Open Access Journals (Sweden)

    Ayman M. Atta

    2016-10-01

    Full Text Available This work first reports the preparation of super-amphiphilic silica-nanogel composites to reduce the contact angle of water to increase the diffusion of pollutant into adsorbents. In this respect, the silica nanoparticles were encapsulated into nanogels based on ionic and nonionic polyacrylamides by dispersion polymerization technique. The morphologies and the dispersion stability of nanogel composites were investigated to clarify the ability of silica-nanogel composites to adsorb at different interfaces. The feasibility of silica polyacrylamide nanogel composites to act as a high-performance adsorbent for removal of methylene blue (MB dye and heavy metals (Co2+ and Ni2+ from aqueous solution was investigated. The surface tension, contact angle, average pore size, and zeta potential of the silica-nanogel composites have been evaluated. The MB dye and heavy metal adsorption capacity achieved Qmax = 438–387 mg/g which is considerably high. The adsorption capacity results are explained from the changes in the morphology of the silica surfaces as recorded from scanning electron microscopy (SEM.

  19. Amphiphilic conjunct of methyl cellulose and well-defined polyvinyl acetate.

    Science.gov (United States)

    Xiao, Congming; Xia, Cunping

    2013-01-01

    Tailor-made conjunct of methyl cellulose (MC) and polyvinyl acetate (PVAc) was synthesized through the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and thiol-ene click reaction. MC was firstly transferred into unsaturated MC (UMC), and then covalently connected with well-defined PVAc obtained by RAFT polymerization of vinyl acetate. The structure of the conjunct polymer (MCV) was confirmed with Fourier transform infrared spectra (FTIR) and proton nuclear magnetic resonance ((1)H NMR). Well-defined MCV was amphiphilic and able to self-assemble into size controllable micelles, which was verified with transmission electron microscopy (TEM) and size distribution analysis. It was found that the mean diameters of the micelles in aqueous solution were 105.6, 96.0 and 75.9 nm when the number average molecular weights of PVAc segments of MCV were 49,300, 32,500 and 18,200, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Biodegradable poly(lactic acid)

    Indian Academy of Sciences (India)

    The fabrication of biodegradable poly(lactic acid) (PLA) microspheres containing total alkaloids of Caulis sinomenii was investigated. The formation, diameter, morphology and properties of the microspheres were characterized using Fourier transform infrared spectroscopy (FT–IR), laser particle size analyser and scanning ...

  1. A comparative study on the effects of amphiphilic and hydrophilic polymers on the release profiles of a poorly water-soluble drug.

    Science.gov (United States)

    Irwan, Anastasia W; Berania, Jacqueline E; Liu, Xueming

    2016-03-01

    This paper reports the use of two crystalline polymers, an amphiphilic Pluronic® F-127 (PF-127) and a hydrophilic poly(ethylene glycol) (PEG6000) as drug delivery carriers for improving the drug release of a poorly water-soluble drug, fenofibrate (FEN), via micelle formation and formation of a solid dispersion (SD). In 10% PF-127 (aq.), FEN showed an equilibrium solubility of ca. 0.6 mg/mL, due to micelle formation. In contrast, in 10% PEG6000 (aq.), FEN only exhibited an equilibrium solubility of 0.0037 mg/mL. FEN-loaded micelles in PF-127 were prepared by direct dissolution and membrane dialysis. Both methods only yielded a highest drug loading (DL) of 0.5%. SDs of FEN in PF-127 and PEG6000, at DLs of 5-80%, were prepared by solvent evaporation. In-vitro dissolution testing showed that both micelles and SDs significantly improved FEN's release rate. The SDs of FEN in PF-127 showed significantly faster release than crystalline FEN, when the DL was as high as 50%, whereas SDs of PEG6000 showed similar enhancement in the release rate when the DL was not more than 20%. The DSC thermograms of SDs of PF-127 exhibited a single phase transition peak at ca. 55-57 °C when the DL was not more than 50%, whereas those in PEG6000 exhibited a similar peak at ca. 61-63 °C when the DL was not more than 35%. When the DL exceeded 50% for SDs of PF-127 and 35% for SDs of PEG6000, DSC thermograms showed two melting peaks for the carrier polymer and FEN, respectively. FT-IR studies revealed that PF-127 has a stronger hydrophobic-hydrophobic interaction with FEN than PEG6000. It is likely that both dispersion and micelle formation contributed to the stronger effect of PF-127 on enhancing the release rate of FEN in its SDs.

  2. 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

  3. Toxicity evaluation of methoxy poly(ethylene oxide)-block-poly(ε-caprolactone) polymeric micelles following multiple oral and intraperitoneal administration to rats.

    Science.gov (United States)

    Binkhathlan, Ziyad; Qamar, Wajhul; Ali, Raisuddin; Kfoury, Hala; Alghonaim, Mohammed

    2017-09-01

    Methoxy poly(ethylene oxide)- block -poly(ɛ-caprolactone) (PEO- b -PCL) copolymers are amphiphilic and biodegradable copolymers designed to deliver a variety of drugs and diagnostic agents. The aim of this study was to synthesize PEO- b -PCL block copolymers and assess the toxic effects of drug-free PEO- b -PCL micelles after multiple-dose administrations via oral or intraperitoneal (ip) administration in rats. Assembly of block copolymers was achieved by co-solvent evaporation method. To investigate the toxicity profile of PEO- b -PCL micelles, sixty animals were divided into two major groups: The first group received PEO- b -PCL micelles (100 mg/kg) by oral gavage daily for seven days, while the other group received the same dose of micelles by ip injections daily for seven days. Twenty-four hours following the last dose, half of the animals from each group were sacrificed and blood and organs (lung, liver, kidneys, heart and spleen) were collected. Remaining animals were observed for further 14 days and was sacrificed at the end of the third week, and blood and organs were collected. None of the polymeric micelles administered caused any significant effects on relative organ weight, animal body weight, leucocytes count, % lymphocytes, liver and kidney toxicity markers and organs histology. Although the dose of copolymers used in this study is much higher than those used for drug delivery, it did not cause any significant toxic effects in rats. Histological examination of all the organs confirmed the nontoxic nature of the micelles.

  4. Toxicity evaluation of methoxy poly(ethylene oxide-block-poly(ε-caprolactone polymeric micelles following multiple oral and intraperitoneal administration to rats

    Directory of Open Access Journals (Sweden)

    Ziyad Binkhathlan

    2017-09-01

    Full Text Available Methoxy poly(ethylene oxide-block-poly(ɛ-caprolactone (PEO-b-PCL copolymers are amphiphilic and biodegradable copolymers designed to deliver a variety of drugs and diagnostic agents. The aim of this study was to synthesize PEO-b-PCL block copolymers and assess the toxic effects of drug-free PEO-b-PCL micelles after multiple-dose administrations via oral or intraperitoneal (ip administration in rats. Assembly of block copolymers was achieved by co-solvent evaporation method. To investigate the toxicity profile of PEO-b-PCL micelles, sixty animals were divided into two major groups: The first group received PEO-b-PCL micelles (100 mg/kg by oral gavage daily for seven days, while the other group received the same dose of micelles by ip injections daily for seven days. Twenty-four hours following the last dose, half of the animals from each group were sacrificed and blood and organs (lung, liver, kidneys, heart and spleen were collected. Remaining animals were observed for further 14 days and was sacrificed at the end of the third week, and blood and organs were collected. None of the polymeric micelles administered caused any significant effects on relative organ weight, animal body weight, leucocytes count, % lymphocytes, liver and kidney toxicity markers and organs histology. Although the dose of copolymers used in this study is much higher than those used for drug delivery, it did not cause any significant toxic effects in rats. Histological examination of all the organs confirmed the nontoxic nature of the micelles.

  5. Facile preparation of a cationic poly(amino acid) vesicle for potential drug and gene co-delivery

    Science.gov (United States)

    Ding, Jianxun; Xiao, Chunsheng; He, Chaoliang; Li, Mingqiang; Li, Di; Zhuang, Xiuli; Chen, Xuesi

    2011-12-01

    A novel pH-responsive poly(amino acid) grafted with oligocation was prepared through the combination of ring-opening polymerization (ROP) and subsequent atom transfer radical polymerization (ATRP). Firstly, poly(γ-2-chloroethyl-L-glutamate) (PCELG) with a pendent 2-chloroethyl group was synthesized through ROP of γ-2-chloroethyl-L-glutamate N-carboxyanhydride (CELG NCA) using n-hexylamine as the initiator. Then, PCELG was used to initiate the ARTP of 2-aminoethyl methacrylate hydrochloride (AMA), yielding poly(L-glutamate)-graft-oligo(2-aminoethyl methacrylate hydrochloride) (PLG-g-OAMA). The pKa of PLG-g-OAMA was 7.3 established by the acid-base titration method. The amphiphilic poly(amino acid) could directly self-assemble into a vesicle in PBS. The vesicle was characterized by TEM and DLS. Hydrophilic DOX·HCl was loaded into the hollow core of the vesicle. The in vitro release behavior of DOX·HCl from the vesicle in PBS could be adjusted by the solution pH. In vitro cell experiments revealed that the vesicle could reduce the toxicity of the DOX·HCl. In addition, the preliminary gel retardation assay displayed that PLG-g-OAMA could efficiently bind DNA at a PLG-g-OAMA/DNA weight ratio of 0.3 or above, indicating its potential use as a gene carrier. More in-depth studies of the PLG-g-OAMA vesicle for drug and gene co-delivery in vitro and in vivo are in progress.

  6. 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; Yi, Xiang; Luxenhofer, Robert; Banks, William A.; Jordan, Rainer; Zimmerman, Matthew C.; Kabanov, Alexander V.

    2013-01-01

    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

  7. Langmuir and Langmuir-Blodgett films of multifunctional, amphiphilic polyethers with cholesterol moieties.

    Science.gov (United States)

    Reuter, Sascha; Hofmann, Anna M; Busse, Karsten; Frey, Holger; Kressler, Jörg

    2011-03-01

    Langmuir films of multifunctional, hydrophilic polyethers containing a hydrophobic cholesterol group (Ch) were studied by surface pressure-mean molecular area (π-mmA) measurements and Brewster angle microscopy (BAM). The polyethers were either homopolymers or diblock copolymers of linear poly(glycerol) (lPG), linear poly(glyceryl glycidyl ether) (lPGG), linear poly(ethylene glycol) (lPEG), or hyperbranched poly(glycerol) (hbPG). Surface pressure measurements revealed that the homopolymers lPG and hbPG did not stay at the water surface after spreading and solvent evaporation, in contrast to lPEG. Because of the incorporation of the Ch group in the polymer structure, stable Langmuir films were formed by Ch-lPG(n), Ch-lPGG(n), and Ch-hbPG(n). The Ch-hbPG(n), Ch-lPEG(n), Ch-lPEG(n)-b-lPG(m), Ch-lPEG(n)-b-lPGG(m), and Ch-lPEG(n)-b-hbPG(m) systems showed an extended plateau region assigned to a phase transition involving the Ch groups. Typical hierarchically ordered morphologies of the LB films on hydrophilic substrates were observed for all Ch-initiated polymers. All LB films showed that Ch of the Ch-initiated homopolymers is able to crystallize. This strong tendency of self-aggregation then triggers further dewetting effects of the respective polyether entities. Fingerlike morphologies are observed for Ch-lPEG(69), since the lPEG(69) entity is able to undergo crystallization after transfer onto the silicon substrate.

  8. Synthesis of amphiphilic macrocyclic molecules from family of aza-porphyrins and study in Langmuir-Blodgett films; Synthese de molecules macrocycliques amphiphiles de la famille des azaporphyrines et etude en films de Langmuir-Blodgett

    Energy Technology Data Exchange (ETDEWEB)

    Palacin, Serge

    1988-03-04

    The cellular automata, also called formal neurons, directly inspired by the knowledge concerning the nervous system, are able to mimic some basic processes of brain, as shape recognition, connecting memory, information sorting... This work aims to build a molecular structure able to fit the working rules of a bidimensional cellular automata. So, amphiphilic molecules belonging to the aza-porphyrin family are synthesized and organized into a planar paving by the Langmuir-Blodgett technique. The regular structure of the outcoming ultra-thin films is studied by linear dichroism and anisotropic electron spin resonance. The physico-chemical behaviour of the amphiphilic molecules is studied and brings about an explanation of the redox phenomena which are observed on the monomolecular film on the water surface. So are we able to outline the future chemical addressing ways of the bidimensional cellular automata. In the end of this dissertation, different ways likely to insure covalent bindings between the active sites and allow the transfer of information within the cellular network are discussed. (author) [French] Les reseaux d'automates, aussi appeles neurones formels, directement inspires par les connaissances nouvelles concernant le fonctionnement du systeme nerveux, sont a l'heure actuelle capables de reproduire certaines operations fondamentales du cerveau, telles que la reconnaissance de forme, la memoire associative, le tri d'information... Le travail a pour but de realiser une structure moleculaire susceptible d'obeir aux regles de fonctionnement d'un automate cellulaire bi-dimensionnel. Dans ce but, des molecules amphiphiles de la famille des azaporphyrines sont synthetisees et organisees en un pavage plan par la methode de Langmuir-Blodgett. La structure reguliere des films ultraminces obtenus est determinee par dichroisme lineaire et resonance paramagnetique electronique anisotrope. Les caracteristiques physico-chimiques des molecules amphiphiles sont etudiees

  9. Azobenzene-aminoglycoside: Self-assembled smart amphiphilic nanostructures for drug delivery.

    Science.gov (United States)

    Deka, Smriti Rekha; Yadav, Santosh; Mahato, Manohar; Sharma, Ashwani Kumar

    2015-11-01

    Here, we have designed and synthesized a novel cationic amphiphilic stimuli-responsive azobenzene-aminoglycoside (a small molecule) conjugate, Azo-AG 5, and characterized it by UV and FTIR. Light responsive nature of Azo-AG 5 was assessed under UV-vis light. Self- assembly of Azo-AG 5 in aqueous solutions into nanostructures and their ability to act as drug carrier were also investigated. The nanostructures of Azo-AG 5 showed average hydrodynamic diameter of ∼ 255 nm with aminoglycoside moiety (neomycin) and 4-dimethylaminoazobenzene forming hydrophilic shell and hydrophobic core, respectively. In the hydrophobic core, eosin and aspirin were successfully encapsulated. Dynamic light scattering (DLS) measurements demonstrated that the nanoassemblies showed expansion and contraction on successive UV and visible light irradiations exhibiting reversible on-off switch for controlling the drug release behavior. Similar behavior was observed when these nanostructures were subjected to pH-change. In vitro drug release studies showed a difference in UV and visible light-mediated release pattern. It was observed that the release rate under UV irradiation was comparatively higher than that observed under visible light. Further, azoreductase-mediated cleavage of the azo moiety in Azo-AG 5 nanoassemblies resulted in the dismantling of the structures into aggregated microstructures. Azo-AG 5 nanostructures having positive surface charge (+9.74 mV) successfully interacted with pDNA and retarded its mobility on agarose gel. Stimuli responsiveness of nanostructures and their on-off switch like behavior ensure the great potential as controlled drug delivery systems and in other biomedical applications such as colon-specific delivery and gene delivery. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Fluorescence and NMR spectroscopy together with molecular simulations reveal amphiphilic characteristics of a Burkholderia biofilm exopolysaccharide.

    Science.gov (United States)

    Kuttel, Michelle M; Cescutti, Paola; Distefano, Marco; Rizzo, Roberto

    2017-06-30

    Biofilms are a collective mode of bacterial life in which a self-produced matrix confines cells in close proximity to each other. Biofilms confer many advantages, including protection from chemicals (including antibiotics), entrapment of useful extracellular enzymes and nutrients, as well as opportunities for efficient recycling of molecules from dead cells. Biofilm matrices are aqueous gel-like structures composed of polysaccharides, proteins, and DNA stabilized by intermolecular interactions that may include non-polar connections. Recently, polysaccharides extracted from biofilms produced by species of the Burkholderia cepacia complex were shown to possess clusters of rhamnose, a 6-deoxy sugar with non-polar characteristics. Molecular dynamics simulations are well suited to characterizing the structure and dynamics of polysaccharides, but only relatively few such studies exist of their interaction with non-polar molecules. Here we report an investigation into the hydrophobic properties of the exopolysaccharide produced by Burkholderia multivorans strain C1576. Fluorescence experiments with two hydrophobic fluorescent probes established that this polysaccharide complexes hydrophobic species, and NMR experiments confirmed these interactions. Molecular simulations to model the hydrodynamics of the polysaccharide and the interaction with guest species revealed a very flexible, amphiphilic carbohydrate chain that has frequent dynamic interactions with apolar molecules; both hexane and a long-chain fatty acid belonging to the quorum-sensing system of B. multivorans were tested. A possible role of the non-polar domains of the exopolysaccharide in facilitating the diffusion of aliphatic species toward specific targets within the biofilm aqueous matrix is proposed. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. Effect of ionizing radiation exposure in the morphology of modified HDPE with amphiphilic particles; Efeito da exposicao a radiacao ionizante na morfologia de PEAD modificado com particulas anfifilicas

    Energy Technology Data Exchange (ETDEWEB)

    Saldanha, Ana Luiza M. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Vivas, Viviane; Zylberberg, Marcel P.; Silva, Tamara I.; Cardoso, Andre Luis V.; Pereira, Iaci M., E-mail: iacipere@gmail.com [Centro Tecnologico do Exercito (CTEx), Rio de Janeiro, RJ (Brazil); Patricio, Patricia S.O. [Centro Federal de Educacao Tecnologica de Minas Gerias (CEFET), Belo Horizonte, MG (Brazil)

    2015-07-01

    One of the techniques used to improve the properties of high performance polymers is the addition of hybrid particles in the polymer. In this context, amphiphilic particles were synthesized in order to provide surface characteristics that enhance the interaction of the interface with the polymeric matrix of high density polyethylene (HDPE). The amphiphilic particles were added to matrix of HDPE and the modified polymer composites were exposed to ionizing radiation (x-rays) for different times. The changes caused by exposure to ionizing radiation in the composite morphology was observed through the small angle x-ray technique. The results suggest that the addition of amphiphilic particles increased the stability of the composite to degradation by radiation. (author)

  12. Yolk–shell Fe3O4@SiO2@PMO: amphiphilic magnetic nanocomposites as an adsorbent and a catalyst with high efficiency and recyclability

    KAUST Repository

    Dai, Jinyu

    2017-01-20

    This study describes the preparation of a multifunctional adsorptive catalyst by the incorporation of ligand groups within the channels of magnetic amphiphilic nanocomposites and attached with Pd nanoparticles. It was clearly demonstrated that Pd2+ was adsorbed by ligand-functionalized materials in water, and then Pd2+ was coordinated with ligand groups. Finally, the Pd nanoparticles were produced via an in situ reduction of Pd2+ by ligand groups through a simple hydrothermal process. Moreover, amphiphilic nanomaterials are viewed as excellent collectors of hydrophobic contaminants in water. The immobilized catalytic active sites with ligand-functionalized nanocomposites were allowed for maximal exposure to the reactants with minimal leaching of the Pd nanoparticles. The unique amphiphilic nanocomposites enabled selective oxidation of alcohols to proceed efficiently in water under aerobic conditions. Moreover, this nanocomposite catalyst could be completely recovered using an external magnet due to the superparamagnetic behavior of Fe3O4 and can be recycled with sustained selectivity and activity.

  13. Conjugation of Lectin to Poly(ε-caprolactone-block-glycopolymer Micelles for In Vitro Intravesical Drug Delivery

    Directory of Open Access Journals (Sweden)

    Ning Ning Li

    2016-10-01

    Full Text Available Amphiphilic poly(ε-caprolactone-block-poly[2-(α-d-mannopyranosyloxy ethyl acrylamide] (PCL-b-PManEA block copolymers were synthesized via a combination of ring-opening polymerization (ROP, reversible addition-fragmentation chain transfer (RAFT polymerization and reactive ester-amine reaction. The PCL-b-PManEA block copolymers can self-assemble into micelles and encapsulate anticancer drug doxorubicin (DOX. To enhance mucoadhesive property of the resulting DOX-loaded PCL-b-PManEA micelles, Concanavalin A (ConA lectin was further conjugated with the micelles. Turbidimetric assay using mucin shows that the DOX-loaded PCL-b-PManEA@ConA micelles are mucoadhesive. DOX release from the DOX-loaded PCL-b-PManEA@ConA micelles in artificial urine at 37 °C exhibits an initial burst release, followed by a sustained and slow release over three days. Confocal laser scanning microscope (CLSM images indicate that the DOX-loaded PCL-b-PManEA@ConA micelles can be effectively internalized by UMUC3 human urothelial carcinoma cells. The DOX-loaded PCL-b-PManEA@ConA micelles exhibit significant cytotoxicity to these cells.

  14. Detection of a new 'nematic-like' phase in liquid crystal-amphiphile mixture by differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Dan, Kaustabh, E-mail: kaustabhdan@gmail.com; Roy, Madhusudan, E-mail: kaustabhdan@gmail.com; Datta, Alokmay, E-mail: kaustabhdan@gmail.com [Surface Physics and Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar Block, Sector 1, Kolkata-700064 (India)

    2014-04-24

    Differential Scanning Calorimetry (DSC) studies on phase transitions of the pure liquid crystalline material N-4-methoxybenzylidene-4-butylaniline (MBBA) and mixtures of MBBA and the amphiphile Stearic Acid (StA) show significant changes in the behavior of mixture from pure MBBA, as regards the nematic-isotropic (N-I) transition temperature (T{sub c}) and other thermodynamic parameters like enthalpy, specific heat and activation energy with concentration of StA. In particular, the convexity of the Arrhenius plot in pure MBBA vanishes with StA concentration pointing to the formation of a new, perhaps 'nematic-like', phase in the mixtures.

  15. Multicompartment micellar aggregates of linear ABC amphiphiles in solvents selective for the C block: A Monte Carlo simulation

    KAUST Repository

    Zhu, Yutian

    2012-01-01

    In the current study, we applied the Monte Carlo method to study the self-assembly of linear ABC amphiphiles composed of two solvophobic A and B blocks and a solvophilic C block. A great number of multicompartment micelles are discovered from the simulations and the detailed phase diagrams for the ABC amphiphiles with different block lengths are obtained. The simulation results reveal that the micellar structure is largely controlled by block length, solvent quality, and incompatibility between the different block types. When the B block is longer than or as same as the terminal A block, a rich variety of micellar structures can be formed from ABC amphiphiles. By adjusting the solvent quality or incompatibility between the different block types, multiple morphological transitions are observed. These morphological sequences are well explained and consistent with all the previous experimental and theoretical studies. Despite the complexity of the micellar structures and morphological transitions observed for the self-assembly of ABC amphiphiles, two important common features of the phase behavior are obtained. In general, the micellar structures obtained in the current study can be divided into zero-dimensional (sphere-like structures, including bumpy-surfaced spheres and sphere-on-sphere structures), one-dimensional (cylinder-like structures, including rod and ring structures), two-dimensional (layer-like structures, including disk, lamella and worm-like and hamburger structures) and three-dimensional (vesicle) structures. It is found that the micellar structures transform from low- to high- dimensional structures when the solvent quality for the solvophobic blocks is decreased. In contrast, the micellar structures transform from high- to low-dimensional structures as the incompatibility between different block types increases. Furthermore, several novel micellar structures, such as the CBABC five-layer vesicle, hamburger, CBA three-layer ring, wormlike shape with

  16. Synthesis of Hydrophilic and Amphiphilic Acryl Sucrose Monomers and Their Copolymerisation with Styrene, Methylmethacrylate and α- and β-Pinenes

    Directory of Open Access Journals (Sweden)

    Maria Teresa Barros

    2010-04-01

    Full Text Available Herein, we report the synthesis of monomethacryloyl sucrose esters, and their successful free radical homo- and co-polymerisation with styrene, methylmethacrylate, α- and β-pinene. The chemical, physical, structural and surface chemical properties of these polymers, containing a hydrophobic olefin backbone and hydrophilic sugar moieties as side chains, have been investigated. Biodegradation tests of the copolymer samples by a microbial fungal culture (Aspergillus niger method showed good biodegradability. The chemical structure and surface chemistry of the synthesized homo- and co-polymers demonstrate their potential technological relevance as amphiphilic and biodegradable polymers.

  17. Synthesis and self-assembly of four-armed star copolymer based on poly(ethylene brassylate) hydrophobic block as potential drug carries

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiucun, E-mail: chenjc@swu.edu.cn; Li, Junzhi; Liu, Jianhua; Weng, Bo; Xu, Liqun [Southwest University, Institute for Clean Energy & Advanced Materials (China)

    2016-05-15

    A novel well-defined four-armed star poly(ethylene brassylate)-b-poly(poly(ethylene glycol)methyl ether methacrylate) (s-PEB-b-P(PEGMA)) was synthesized and self-assembled via the combination of ring-opening polymerization and reversible addition-fragmentation chain transfer polymerization (RAFT) in this work. It proceeded firstly with the synthesis of hydrophobic four-armed star homopolymer of ethylene brassylate (EB) via ROP with organic catalyst, followed by the esterification reaction of s-PEB with chain transfer agent. Afterward, RAFT polymerization of PEGMA monomer was initialed using PEB-based macro-RAFT agent, resulting in the target amphiphilic four-armed star copolymer. The obtained s-PEB-b-P(PEGMA) can assemble into micelles with PEB segments as core and P(PEGMA) segments as shell in aqueous solution. The self-assembly behavior was studied by dynamic light scattering and transmission electron microscope. The micelles of s-PEB-b-P(PEGMA) exhibited higher loading capacity of the anticancer drug doxorubicin (DOX). The investigation of DOX release from the micelles demonstrated that the release rate of the hydrophobic drug could be effectively controlled.Graphical Abstract.

  18. 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.

  19. Microfluidics for producing poly (lactic-co-glycolic acid)-based pharmaceutical nanoparticles.

    Science.gov (United States)

    Li, Xuanyu; Jiang, Xingyu

    2017-12-24

    Microfluidic chips allow the rapid production of a library of nanoparticles (NPs) with distinct properties by changing the precursors and the flow rates, significantly decreasing the time for screening optimal formulation as carriers for drug delivery compared to conventional methods. The batch-to-batch reproducibility which is essential for clinical translation is achieved by precisely controlling the precursors and the flow rate, regardless of operators. Poly (lactic-co-glycolic acid) (PLGA) is the most widely used Food and Drug Administration (FDA)-approved biodegradable polymers. Researchers often combine PLGA with lipids or amphiphilic molecules to assemble into a core/shell structure to exploit the potential of PLGA-based NPs as powerful carriers for cancer-related drug delivery. In this review, we discuss the advantages associated with microfluidic chips for producing PLGA-based functional nanocomplexes for drug delivery. These laboratory-based methods can readily scale up to provide sufficient amount of PLGA-based NPs in microfluidic chips for clinical studies and industrial-scale production. Copyright © 2017. Published by Elsevier B.V.

  20. Design and synthesis of an amphiphilic graft hydrogel having a hydrophobic domain formed by multiple interactions

    Energy Technology Data Exchange (ETDEWEB)

    Nitta, Kyohei [Department of Life and Functional Material Science, Graduate School of Natural Science, Konan University, 8-9-1 Okamoto, Higashinada, Kobe 658-8501 (Japan); Japan Society for the Promotion of Science (DC1), Ichibancho, Chiyoda, Tokyo 102-8471 (Japan); Kimoto, Atsushi [Department of Chemistry of Functional Molecules, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada, Kobe 658-8501 (Japan); Watanabe, Junji, E-mail: junjiknd@konan-u.ac.jp [Department of Chemistry of Functional Molecules, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada, Kobe 658-8501 (Japan)

    2016-11-01

    A novel hydrogel having hydrophobic oligo segments and hydrophilic poly(acrylamidoglycolic acid) (PAGA) as pH responsive polymer segments was designed and synthesized to be used as a soft biomaterial. Poly(trimethylene carbonate) (PTMC) as the side chain, for which the degrees of polymerization were 9, 19, and 49, and the composition ratios were 1, 5, and 10 mol%, was used as the oligo segment in the hydrogel. The swelling ratio of the hydrogel was investigated under various changes in conditions such as pH, temperature, and hydrogen bonding upon urea addition. Under pH 2–11 conditions, the graft gel reversibly swelled and shrank due to the effect of PAGA main chain. The interior morphology and skin layer of the hydrogel was observed by a scanning electron microscope. The hydrogel composed of PAGA as the hydrophilic polymer backbone had a sponge-like structure, with a pore size of approximately 100 μm. On the other hand, upon increasing the ratio of trimethylene carbonate (TMC) units in the hydrogel, the pores became smaller or disappeared. Moreover, thickness of the skin layer significantly increased with the swelling ratio depended on the incorporation ratios of the PTMC macromonomer. Molecular incorporation in the hydrogel was evaluated using a dye as a model drug molecule. These features would play an important role in drug loading. Increasing the ratio of TMC units favored the adsorption of the dye and activation of the incorporation behavior. - Highlights: • Hydrogen bonding and hydrophobic interaction are dominant factor for forming hydrogels. • Hydrogel properties were tuned by changing in graft length and macromonomer content in feed. • The resulting graft gel could encapsulate and retain organic dye in the hydrogel. • Poly(trimethylene carbonate) segment in the hydrogel was dominant unit for hydrogel.

  1. Design and synthesis of an amphiphilic graft hydrogel having a hydrophobic domain formed by multiple interactions

    International Nuclear Information System (INIS)

    Nitta, Kyohei; Kimoto, Atsushi; Watanabe, Junji

    2016-01-01

    A novel hydrogel having hydrophobic oligo segments and hydrophilic poly(acrylamidoglycolic acid) (PAGA) as pH responsive polymer segments was designed and synthesized to be used as a soft biomaterial. Poly(trimethylene carbonate) (PTMC) as the side chain, for which the degrees of polymerization were 9, 19, and 49, and the composition ratios were 1, 5, and 10 mol%, was used as the oligo segment in the hydrogel. The swelling ratio of the hydrogel was investigated under various changes in conditions such as pH, temperature, and hydrogen bonding upon urea addition. Under pH 2–11 conditions, the graft gel reversibly swelled and shrank due to the effect of PAGA main chain. The interior morphology and skin layer of the hydrogel was observed by a scanning electron microscope. The hydrogel composed of PAGA as the hydrophilic polymer backbone had a sponge-like structure, with a pore size of approximately 100 μm. On the other hand, upon increasing the ratio of trimethylene carbonate (TMC) units in the hydrogel, the pores became smaller or disappeared. Moreover, thickness of the skin layer significantly increased with the swelling ratio depended on the incorporation ratios of the PTMC macromonomer. Molecular incorporation in the hydrogel was evaluated using a dye as a model drug molecule. These features would play an important role in drug loading. Increasing the ratio of TMC units favored the adsorption of the dye and activation of the incorporation behavior. - Highlights: • Hydrogen bonding and hydrophobic interaction are dominant factor for forming hydrogels. • Hydrogel properties were tuned by changing in graft length and macromonomer content in feed. • The resulting graft gel could encapsulate and retain organic dye in the hydrogel. • Poly(trimethylene carbonate) segment in the hydrogel was dominant unit for hydrogel.

  2. Interfacial electrostatics of poly(vinylamine hydrochloride), poly(diallyldimethylammonium chloride), poly-l-lysine, and poly-l-arginine interacting with lipid bilayers.

    Science.gov (United States)

    McGeachy, A C; Dalchand, N; Caudill, E R; Li, T; Doğangün, M; Olenick, L L; Chang, H; Pedersen, J A; Geiger, F M

    2018-04-25

    Charge densities of cationic polymers adsorbed to lipid bilayers are estimated from second harmonic generation (SHG) spectroscopy and quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. The systems surveyed included poly(vinylamine hydrochloride) (PVAm), poly(diallyldimethylammonium chloride) (PDADMAC), poly-l-lysine (PLL), and poly-l-arginine (PLR), as well as polyalcohol controls. Upon accounting for the number of positive charges associated with each polyelectrolyte, the binding constants and apparent free energies of adsorption as estimated from SHG data are comparable despite differences in molecular masses and molecular structure, with ΔGads values of -61 ± 2, -58 ± 2, -57 ± 1, -52 ± 2, -52 ± 1 kJ mol-1 for PDADMAC400, PDADMAC100, PVAm, PLL, and PLR, respectively. Moreover, we find charge densities for polymer adlayers of approximately 0.3 C m-2 for poly(diallyldimethylammonium chloride) while those of poly(vinylamine) hydrochloride, poly-l-lysine, and poly-l-arginine are approximately 0.2 C m-2. Time-dependent studies indicate that polycation adsorption to supported lipid bilayers is only partially reversible for most of the polymers explored. Poly(diallyldimethylammonium chloride) does not demonstrate reversible binding even over long timescales (>8 hours).

  3. Co-assembly of Peptide Amphiphiles and Lipids into Supramolecular Nanostructures Driven by Anion-π Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zhilin; Erbas, Aykut; Tantakitti, Faifan; Palmer, Liam C.; Jackman, Joshua A.; Olvera de la Cruz, Monica; Cho, Nam-Joon; Stupp, Samuel I. (Nanyang); (NWU)

    2017-06-01

    Co-assembly of binary systems driven by specific non-covalent interactions can greatly expand the structural and functional space of supramolecular nanostructures. We report here on the self-assembly of peptide amphiphiles and fatty acids driven primarily by anion-π interactions. The peptide sequences investigated were functionalized with a perfluorinated phenylalanine residue to promote anion-π interactions with carboxylate headgroups in fatty acids. These interactions were verified here by NMR and circular dichroism experiments as well as investigated using atomistic simulations. Positioning the aromatic units close to the N-terminus of the peptide backbone near the hydrophobic core of cylindrical nanofibers leads to strong anion-π interactions between both components. With a low content of dodecanoic acid in this position, the cylindrical morphology is preserved. However, as the aromatic units are moved along the peptide backbone away from the hydrophobic core, the interactions with dodecanoic acid transform the cylindrical supramolecular morphology into ribbon-like structures. Increasing the ratio of dodecanoic acid to PA leads to either the formation of large vesicles in the binary systems where the anion-π interactions are strong, or a heterogeneous mixture of assemblies when the peptide amphiphiles associate weakly with dodecanoic acid. Our findings reveal how co-assembly involving designed specific interactions can drastically change supramolecular morphology and even cross from nano to micro scales.

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

    Science.gov (United States)

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

    2017-09-12

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

  5. Self-consistent field theoretic simulations of amphiphilic triblock copolymer solutions: Polymer concentration and chain length effects

    Directory of Open Access Journals (Sweden)

    X.-G. Han

    2014-06-01

    Full Text Available Using the self-consistent field lattice model, polymer concentration φP and chain length N (keeping the length ratio of hydrophobic to hydrophilic blocks constant the effects on temperature-dependent behavior of micelles are studied, in amphiphilic symmetric ABA triblock copolymer solutions. When chain length is increased, at fixed φP, micelles occur at higher temperature. The variations of average volume fraction of stickers φcos and the lattice site numbers Ncols at the micellar cores with temperature are dependent on N and φP, which demonstrates that the aggregation of micelles depends on N and φP. Moreover, when φP is increased, firstly a peak appears on the curve of specific heat CV for unimer-micelle transition, and then in addition a primary peak, the secondary peak, which results from the remicellization, is observed on the curve of CV. For a long chain, in intermediate and high concentration regimes, the shape of specific heat peak markedly changes, and the peak tends to be a more broad peak. Finally, the aggregation behavior of micelles is explained by the aggregation way of amphiphilic triblock copolymer. The obtained results are helpful in understanding the micellar aggregation process.

  6. Photo-switching of a non-ionic azobenzene amphiphile in Langmuir and Langmuir-Blodgett films.

    Science.gov (United States)

    Piosik, Emilia; Kotkowiak, Michał; Korbecka, Izabela; Galewski, Zbigniew; Martyński, Tomasz

    2017-08-30

    The concept of programmable and reconfigurable soft matter has emerged in science in the last few decades and can be realized by photoisomerization of azobenzene derivatives. This possibility results in great application potential of these compounds in optical storage devices, molecular junctions of electronic devices, command layers of liquid crystal displays or holographic gratings. In this paper, we present the results of a study on the organization and isomerization of the non-ionic and amphiphilic methyl 4-[(E)-2-[4-(nonyloxy)phenyl]diazen-1-yl]benzoate (LCA) in a 2D layer architecture of Langmuir and Langmuir-Blodgett (LB) films supported by spectroscopic studies on LCA chloroform solutions. Our investigation has shown a significantly different molecular organization of LCA depending on the ratio of trans and cis isomers in the monolayers. Taking advantage of a relatively low packing density and aggregation strength in the cis-LCA monolayer, we demonstrated the reversible isomerization in the LB film initially formed of LCA molecules in the cis form, while in the trans-LCA monolayer this effect was not observed. Our approach allows the formation of a switchable monolayer made of the amphiphilic LCA showing liquid crystalline properties without introducing an ionic group into the molecule structure, mixing with another compound or changing the subphase pH to provide free space for the molecules' isomerization.

  7. Synthesis of Fluorinated Amphiphilic Block Copolymers Based on PEGMA, HEMA, and MMA via ATRP and CuAAC Click Chemistry

    Directory of Open Access Journals (Sweden)

    Fatime Eren Erol

    2014-01-01

    Full Text Available Synthesis of fluorinated amphiphilic block copolymers via atom transfer radical polymerization (ATRP and Cu(I catalyzed Huisgen 1,3-dipolar cycloaddition (CuAAC was demonstrated. First, a PEGMA and MMA based block copolymer carrying multiple side-chain acetylene moieties on the hydrophobic segment for postfunctionalization was carried out. This involves the synthesis of a series of P(HEMA-co-MMA random copolymers to be employed as macroinitiators in the controlled synthesis of P(HEMA-co-MMA-block-PPEGMA block copolymers by using ATRP, followed by a modification step on the hydroxyl side groups of HEMA via Steglich esterification to afford propargyl side-functional polymer, alkyne-P(HEMA-co-MMA-block-PPEGMA. Finally, click coupling between side-chain acetylene functionalities and 2,3,4,5,6-pentafluorobenzyl azide yielded fluorinated amphiphilic block copolymers. The obtained polymers were structurally characterized by 1H-NMR, 19F-NMR, FT-IR, and GPC. Their thermal characterizations were performed using DSC and TGA.

  8. Development of a new LDL-based transport system for hydrophobic/amphiphilic drug delivery to cancer cells.

    Science.gov (United States)

    Huntosova, Veronika; Buzova, Diana; Petrovajova, Dana; Kasak, Peter; Nadova, Zuzana; Jancura, Daniel; Sureau, Franck; Miskovsky, Pavol

    2012-10-15

    Low-density lipoproteins (LDL), a natural in vivo carrier of cholesterol in the vascular system, play a key role in the delivery of hydrophobic/amphiphilic photosensitizers to tumor cells in photodynamic therapy of cancer. To make this delivery system even more efficient, we have constructed a nano-delivery system by coating of LDL surface by dextran. Fluorescence spectroscopy, confocal fluorescence imaging, stopped-flow experiments and flow-cytometry were used to characterize redistribution of hypericin (Hyp), a natural occurring potent photosensitizer, loaded in LDL/dextran complex to free LDL molecules as well as to monitor cellular uptake of Hyp by U87-MG cells. It is shown that the redistribution process of Hyp between LDL molecules is significantly suppressed by dextran coating of LDL surface. The modification of LDL molecules by dextran does not inhibit their recognition by cellular LDL receptors and U-87 MG cellular uptake of Hyp loaded in LDL/dextran complex appears to be similar to that one observed for Hyp transported by unmodified LDL particles. Thus, it is proposed that dextran modified LDL molecules could be used as a basis for construction of a drug transport system for targeted delivery of hydrophobic/amphiphilic drugs to cancer cells expressing high level of LDL receptors. Copyright © 2012 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  10. Molecular fouling resistance of zwitterionic and amphiphilic initiated chemically vapor-deposited (iCVD) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, R; Goktekin, E; Wang, MH; Gleason, KK

    2014-08-08

    Biofouling is a universal problem in various applications ranging from water purification to implantable biomedical devices. Recent advances in surface modification have created a rich library of antifouling surface chemistries, many of which can be categorized into one of the two groups: hydrophilic surfaces or amphiphilic surfaces. We report the straightforward preparation of antifouling thin film coatings in both categories via initiated chemical vapor deposition. A molecular force spectroscopy-based method is demonstrated as a rapid and quantitative assessment tool for comparing the differences in antifouling characteristics. The fouling propensity of single molecules, as opposed to bulk protein solution or bacterial culture, is assessed. This method allows for the interrogation of molecular interaction without the complication resulted from protein conformational change or micro-organism group interactions. The molecular interaction follows the same trend as bacterial adhesion results obtained previously, demonstrating that molecular force probe is a valid method for the quantification and mechanistic examination of fouling. In addition, the molecular force spectroscopy-based method is able to distinguish differences in antifouling capability that is not resolvable by traditional static protein adsorption tests. To lend further insight into the intrinsic fouling resistance of zwitterionic and amphiphilic surface chemistries, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, advancing and receding water contact angles, and atomic force microscopy are used to elucidate the film properties that are relevant to their antifouling capabilities.

  11. Water ordering controls the dynamic equilibrium of micelle-fibre formation in self-assembly of peptide amphiphiles.

    Science.gov (United States)

    Deshmukh, Sanket A; Solomon, Lee A; Kamath, Ganesh; Fry, H Christopher; Sankaranarayanan, Subramanian K R S

    2016-08-24

    Understanding the role of water in governing the kinetics of the self-assembly processes of amphiphilic peptides remains elusive. Here, we use a multistage atomistic-coarse-grained approach, complemented by circular dichroism/infrared spectroscopy and dynamic light scattering experiments to highlight the dual nature of water in driving the self-assembly of peptide amphiphiles (PAs). We show computationally that water cage formation and breakage near the hydrophobic groups control the fusion dynamics and aggregation of PAs in the micellar stage. Simulations also suggest that enhanced structural ordering of vicinal water near the hydrophilic amino acids shifts the equilibrium towards the fibre phase and stimulates structure and order during the PA assembly into nanofibres. Experiments validate our simulation findings; the measured infrared O-H bond stretching frequency is reminiscent of an ice-like bond which suggests that the solvated water becomes increasingly ordered with time in the assembled peptide network, thus shedding light on the role of water in a self-assembly process.

  12. A novel ionic amphiphilic chitosan derivative as a stabilizer of nanoemulsions: Improvement of antimicrobial activity of Cymbopogon citratus essential oil.

    Science.gov (United States)

    Bonferoni, Maria Cristina; Sandri, Giuseppina; Rossi, Silvia; Usai, Donatella; Liakos, Ioannis; Garzoni, Alice; Fiamma, Maura; Zanetti, Stefania; Athanassiou, Athanassia; Caramella, Carla; Ferrari, Franca

    2017-04-01

    Amphiphilic chitosans have been recently proposed to improve delivery of poorly soluble drugs. In the present paper a derivative obtained by ionic interaction between chitosan and oleic acid was for the first time studied to physically stabilize o/w nanoemulsions of an antimicrobial essential oil, Cymbopogon citratus (Lemongrass), in a low energy and mild conditions emulsification process. The novel combination of spontaneous emulsification process with chitosan oleate amphiphilic properties resulted in a stable dispersion of a few hundred nanometer droplets. Positive zeta potential confirmed the presence of a chitosan shell around the oil droplets, which is responsible for the nanoemulsion physical stabilization and for the maintenance of chitosan bioactive properties, such as mucoadhesion. Cytotoxicity test was performed on four different cell lines (HEp-2, Caco-2, WKD and McCoy cells) showing biocompatibility of the system. The maintenance and in some cases even a clear improvement in the essential oil antimicrobial activity towards nine bacterial and ten fungal strains, all of clinical relevance was verified for Lemongrass nanoemulsion. Copyright © 2017. Published by Elsevier B.V.

  13. Self-Delivery Nanoparticles of Amphiphilic Methotrexate-Gemcitabine Prodrug for Synergistic Combination Chemotherapy via Effect of Deoxyribonucleotide Pools.

    Science.gov (United States)

    Wang, Yao; Huang, Ping; Hu, Minxi; Huang, Wei; Zhu, Xinyuan; Yan, Deyue

    2016-11-16

    The distinct and complementary biochemical mechanisms of folic acid analog methotrexate (MTX) and cytidine analog gemcitabine (GEM) make their synergistic combination effective. Unfortunately, such a combination faces severe pharmacokinetic problems and several transportation barriers. To overcome these problems, a new strategy of amphiphilic small molecule prodrug (ASMP) is developed to improve their synergistic combination effect. The ASMP was prepared by the amidation of the hydrophilic GEM with the hydrophobic MTX at a fixed ratio. Owing to its inherent amphiphilicity, the MTX-GEM ASMP self-assembled into stable nanoparticles (ASMP-NPs) with high drug loading capacity (100%), in which the MTX and GEM could self-deliver without any carriers and release synchronously in cancer cells. In vitro studies showed that the MTX-GEM ASMP-NPs could greatly improve the synergistic combination effects by the reason of arresting more S phase of the cell cycle and reducing levels of deoxythymidine triphosphate (dTTP), deoxyadenosine triphosphate (dATP), and deoxycytidine triphosphate (dCTP). The stronger synergistic effects caused the higher cell cytotoxicity and apoptotic ratio, and circumvented the multidrug resistance (MDR) of tumor cells. Additionally, MTX-GEM ASMP-NPs could achieve the same anticancer effect with the greatly reduced dosage compared with the free drugs according to the dose-reduction index (DRI) values of MTX and GEM in MTX-GEM ASMP-NPs, which may be beneficial for reducing the side effects.

  14. Zero-order release of lysozyme from (poly)ethylene glycol)/poly(butylene terephthalate) matrices

    NARCIS (Netherlands)

    Bezemer, J.M.; Radersma, R.; Grijpma, Dirk W.; Dijkstra, Pieter J.; Feijen, Jan; van Blitterswijk, Clemens

    2000-01-01

    Protein release from a series of biodegradable poly(ether ester) multiblock copolymers, based on poly(ethylene glycol) (PEG) and poly(butylene terephthalate) (PBT) was investigated. Lysozyme-containing PEG/PBT films and microspheres were prepared using an emulsion technique. Proteins were

  15. 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...

  16. Self-assembled nanoparticles based on amphiphilic chitosan derivative and arginine for oral curcumin delivery

    Directory of Open Access Journals (Sweden)

    Raja MA

    2016-09-01

    Full Text Available Mazhar Ali Raja, Shah Zeenat, Muhammad Arif, Chenguang Liu College of Marine Life Science, Ocean University of China, Qingdao, Shandong, People’s Republic of China Abstract: Curcumin (Cur is a striking anticancer agent, but its low aqueous solubility, poor absorption, hasty metabolism, and elimination limit its oral bioavailability and consequently hinder its development as a drug. To redress these limitations, amphiphilic chitosan (CS conjugate with improved mucoadhesion and solubility over a wider pH range was developed by modification with hydrophobic acrylonitrile (AN and hydrophilic arginine (Arg; the synthesized conjugate (AN–CS–Arg, which was well characterized by Fourier transform infrared and 1H nuclear magnetic resonance spectroscopy. Results of critical aggregation concentration revealed that the AN–CS–Arg conjugate had low critical aggregation concentration and was prone to form self-assembled nanoparticles (NPs in aqueous medium. Cur-encapsulated AN–CS–Arg NPs (AN–CS–Arg/Cur NPs were developed by a simple sonication method and characterized for the physicochemical parameters such as zeta potential, particle size, and drug encapsulation. The results showed that zeta potential of the prepared NPs was 40.1±2.81 mV and the average size was ~218 nm. A considerable improvement in the aqueous solubility of Cur was observed after encapsulation into AN–CS–Arg/Cur NPs. With the increase in Cur concentration, loading efficiency increased but encapsulation efficiency decreased. The in vitro release profile exhibited sustained release pattern from the AN–CS–Arg/Cur NPs in typical biological buffers. The ex vivo mucoadhesion study revealed that AN–CS–Arg/Cur NPs had greater mucoadhesion than the control CS NPs. Compared with free Cur solution, AN–CS–Arg/Cur NPs showed stronger dose-dependent cytotoxicity against HT-29 cells. In addition, it was observed that cell uptake of AN–CS–Arg/Cur NPs was much higher

  17. Ionic conducting poly-benzimidazoles

    International Nuclear Information System (INIS)

    Jouanneau, J.

    2006-11-01

    Over the last years, many research works have been focused on new clean energy systems. Hydrogen fuel cell seems to be the most promising one. However, the large scale development of this technology is still limited by some key elements. One of them is the polymer electrolyte membrane 'Nafion' currently used, for which the ratio performance/cost is too low. The investigations we carried out during this thesis work are related to a new class of ionic conducting polymer, the sulfonated poly-benzimidazoles (sPBI). Poly-benzimidazoles (PBI) are aromatic heterocyclic polymers well-known for their excellent thermal and chemical stability. Ionic conduction properties are obtained by having strong acid groups (sulfonic acid SO 3 H) on the macromolecular structure. For that purpose, we first synthesized sulfonated monomers. Their poly-condensation with an appropriate non-sulfonated co-monomer yields to sPBI with sulfonation range from 0 to 100 per cent. Three different sPBI structures were obtained, and verified by appropriate analytical techniques. We also showed that the protocol used for the synthesis resulted in high molecular weights polymers. We prepared ionic conducting membrane by casting sPBI solutions on glass plates. Their properties of stability, water swelling and ionic conductivity were investigated. Surprisingly, the behaviour of sPBI was quite different from the other sulfonated aromatic polymers with same amount of SO 3 H, their stability was much higher, but their water swelling and ionic conductivity were quite low. We attributed these differences to strong ionic interactions between the sulfonic acid groups and the basic benzimidazole groups of our polymers. However, we managed to solve this problem synthesizing very highly sulfonated PBI, obtaining membranes with a good balance between all the properties necessary. (author)

  18. Poly(ethylene oxide) functionalization

    Science.gov (United States)

    Pratt, Russell Clayton

    2014-04-08

    A simple procedure is provided by which the hydroxyl termini of poly(ethylene oxide) can be appended with functional groups to a useful extent by reaction and precipitation. The polymer is dissolved in warmed toluene, treated with an excess of organic base and somewhat less of an excess of a reactive acylating reagent, reacted for several hours, then precipitated in isopropanol so that the product can be isolated as a solid, and salt byproducts are washed away. This procedure enables functionalization of the polymer while not requiring laborious purification steps such as solvent-solvent extraction or dialysis to remove undesirable side products.

  19. Synthesis and Self-Assembly of Amphiphilic Triblock Terpolymers with Complex Macromolecular Architecture

    KAUST Repository

    Polymeropoulos, George; Zapsas, George; Hadjichristidis, Nikolaos; Avgeropoulos, Apostolos

    2015-01-01

    Two star triblock terpolymers (PS-b-P2VP-b-PEO)3 and one dendritic-like terpolymer [PS-b-P2VP-b-(PEO)2]3 of PS (polystyrene), P2VP (poly(2-vinylpyridine)), and PEO (poly(ethylene oxide)), never reported before, were synthesized by combining atom transfer radical and anionic polymerizations. The synthesis involves the transformation of the -Br groups of the previously reported Br-terminated 3-arm star diblock copolymers to one or two -OH groups, followed by anionic polymerization of ethylene oxide to afford the star or dendritic structure, respectively. The well-defined structure of the terpolymers was confirmed by static light scattering, size exclusion chromatography, and NMR spectroscopy. The self-assembly in solution and the morphology in bulk of the terpolymers, studied by dynamic light scattering and transmission electron microscopy, respectively, reveal new insights in the phase separation of these materials with complex macromolecular architecture. © 2015 American Chemical Society.

  20. Unlocking Chain Exchange in Highly Amphiphilic Block Polymer Micellar Systems: Influence of Agitation.

    Science.gov (United States)

    Murphy, Ryan P; Kelley, Elizabeth G; Rogers, Simon A; Sullivan, Millicent O; Epps, Thomas H

    2014-11-18

    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 sparging. Subsequently, the extent of chain exchange between micelles was quantified using small angle neutron scattering. Rapid vortex mixing induced chain exchange within minutes, as evidenced by a monotonic decrease in scattered intensity, whereas Couette flow and sparging did not lead to measurable chain exchange over the examined time scale of hours. The linear kinetics with respect to agitation time suggested a surface-limited exchange process at the air-water interface. These findings demonstrate the strong influence of processing conditions on block polymer solution assemblies.

  1. Development and Characterization of Biocompatible Fullerene [C60]/Amphiphilic Block Copolymer Nanocomposite

    Directory of Open Access Journals (Sweden)

    Alok Chaurasia

    2015-01-01

    Full Text Available We report a supramolecular process for the synthesis of well-defined fullerene (C60/polymer colloid nanocomposites in an aqueous solution via complex formation. A biocompatible triblock poly(4-vinylpyridine-b-polyethylene-b-poly(4-vinylpyridine, P4VP8-b-PEO105-b-P4VP8, was synthesized by atom transfer radical polymerization. The block copolymer formed complexes with C60 in toluene and resulted in fullerene assembly in cluster form. Nanocomposite dispersion in an aqueous solution could be obtained using an aged solution of the polymer/C60/toluene solution by a solvent evaporation technique. The UV-Vis and FTIR spectroscopy confirmed the complex formation of fullerene with the polymer which plays a significant role in controlling the PDI and size of polymer/C60 micelles in the toluene solution. The particle size and morphology of P4VP8-b-PEO105-b-P4VP8 and P4VP8-b-PEO105-b-P4VP8/C60 mixture were studied by dynamic light scattering (DLS and transmission electron microscopy (TEM. In a cytotoxicity test, both pure polymer and the resulting polymer/C60 composite in water showed more than 90% cell viability at 1 mg/mL concentration.

  2. Amphiphilic Fluorinated Block Copolymer Synthesized by RAFT Polymerization for Graphene Dispersions

    Directory of Open Access Journals (Sweden)

    Hyang Moo Lee

    2016-03-01

    Full Text Available Despite the superior properties of graphene, the strong π–π interactions among pristine graphenes yielding massive aggregation impede industrial applications. For non-covalent functionalization of highly-ordered pyrolytic graphite (HOPG, poly(2,2,2-trifluoroethyl methacrylate-block-poly(4-vinyl pyridine (PTFEMA-b-PVP block copolymers were prepared by reversible addition-fragmentation chain transfer (RAFT polymerization and used as polymeric dispersants in liquid phase exfoliation assisted by ultrasonication. The HOPG graphene concentrations were found to be 0.260–0.385 mg/mL in methanolic graphene dispersions stabilized with 10 wt % (relative to HOPG PTFEMA-b-PVP block copolymers after one week. Raman and atomic force microscopy (AFM analyses revealed that HOPG could not be completely exfoliated during the sonication. However, on-line turbidity results confirmed that the dispersion stability of HOPG in the presence of the block copolymer lasted for one week and that longer PTFEMA and PVP blocks led to better graphene dispersibility. Force–distance (F–d analyses of AFM showed that PVP block is a good graphene-philic block while PTFEMA is methanol-philic.

  3. Synthesis and Self-Assembly of Amphiphilic Triblock Terpolymers with Complex Macromolecular Architecture

    KAUST Repository

    Polymeropoulos, George

    2015-11-25

    Two star triblock terpolymers (PS-b-P2VP-b-PEO)3 and one dendritic-like terpolymer [PS-b-P2VP-b-(PEO)2]3 of PS (polystyrene), P2VP (poly(2-vinylpyridine)), and PEO (poly(ethylene oxide)), never reported before, were synthesized by combining atom transfer radical and anionic polymerizations. The synthesis involves the transformation of the -Br groups of the previously reported Br-terminated 3-arm star diblock copolymers to one or two -OH groups, followed by anionic polymerization of ethylene oxide to afford the star or dendritic structure, respectively. The well-defined structure of the terpolymers was confirmed by static light scattering, size exclusion chromatography, and NMR spectroscopy. The self-assembly in solution and the morphology in bulk of the terpolymers, studied by dynamic light scattering and transmission electron microscopy, respectively, reveal new insights in the phase separation of these materials with complex macromolecular architecture. © 2015 American Chemical Society.

  4. The thermal degradation of poly(iso-butyl methacrylate and poly(sec-butyl methacrylate

    Directory of Open Access Journals (Sweden)

    IVANKA G. POPOVIC

    2000-12-01

    Full Text Available The non-oxidative thermal degradation of poly(iso-butyl methacrylate and poly(sec-butyl methacrylate was investigated by studying changes in the polymer residue. Due to the different number of b-hydrogens in their ester substituents, these two polymeric isomers behave differently when subjected to elevated temperatures. Poly(iso-butyl methacrylate degrades quantitatively by depolymerisation with zip lengths of the same order of magnitude as those of poly(methyl methacrylate. Poly(sec-butyl methacrylate degrades by a combined degradation mechanism of depolymerisation and de-esterification. De-esterification becomes a significant thermolysis route at temperatures higher than 240°C.

  5. Amphiphilic polymer promoted assembly of macroporous graphene/SnO2 frameworks with tunable porosity for high-performance lithium storage.

    Science.gov (United States)

    Huang, Yanshan; Wu, Dongqing; Wang, Jinzuan; Han, Sheng; Lv, Lu; Zhang, Fan; Feng, Xinliang

    2014-06-12

    3D macroporous graphene/SnO2 frameworks (MGTFs) are fabricated by amphiphilic polymer-promoted assembly method, which exhibit controllable macroporous structure and outstanding lithium storage performance. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    DEFF Research Database (Denmark)

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

    2004-01-01

    , Triton X-100, and reduced Triton X-100) that make lipid bilayers less "stiff", as measured using gA channels, shift the voltage dependence of sodium channel inactivation toward more hyperpolarized potentials. At low amphiphile concentration, the magnitude of the shift is linearly correlated to the change...

  7. Evaluation of chromatographic conditions in reversed phase liquid chromatography-mass spectrometry systems for fingerprinting of polar and amphiphilic plant metabolites

    DEFF Research Database (Denmark)

    Nielsen, Nikoline Juul; Tomasi, Giorgio; Christensen, Jan H.

    2016-01-01

    Metabolic fingerprinting is a relatively young scientific discipline requiring robust, yet flexible and fit-for-purpose analytical methods. Here, we introduce a simple approach to select reversed phase LC systems with electrospray MS detection for fingerprinting of polar and amphiphilic plant met...

  8. Synthesis and aqueous phase behavior of thermoresponsive biodegradable poly(D,L-3-methylglycolide)-block-poly(ethyelene glycol)-block-poly(D,L-3-methylglycolide) triblock copolymers

    NARCIS (Netherlands)

    Zhong, Zhiyuan; Dijkstra, Pieter J.; Feijen, Jan; Kwon, Young-Min; Bae, You Han; Kim, Sung Wan

    2002-01-01

    Novel biodegradable thermosensitive triblock copolymers of poly(D,L-3-methylglycolide)-block-poly(ethylene glycol)-block-poly(D,L-3-methylglycolide) (PMG-PEG-PMG) have been synthesized. Ring-opening polymerization of D,L-3-methyl-glycolide (MG) initiated with poly(ethylene glycol) (PEG) and

  9. Synthesis and characterization of poly aniline/wood and poly aniline/carbon composites

    International Nuclear Information System (INIS)

    Kanwal, F.; Siddiqi, S.A.; Tasleem, S.

    2009-01-01

    Conducting polymers have shown many applications in the field of nano science, nano technology and nuclear science. Poly aniline (PAN I) is the most studied conducting polymer due to its environmental stability, easy availability of its raw materials, and simple synthesis. We have synthesized poly aniline and two of its conducting composites i.e., poly aniline-carbon and poly aniline-wood in acidic medium (HCI) using K/sub 2/Cr/sub 2/O/sub 7/ as oxidizing agent. All samples were characterized by FTIR and four-probe d.c. conductivity methods The synthesis was carried out at two different temperatures (0 degree C and -5 degree C) and it was found that the yield and conductivity were maximum at lower temperature (-5 degree C). The poly aniline-carbon composites showed enhanced conductivity whereas poly aniline-wood composites showed reduced conductivity when compared with the conductivity of pure poly aniline. (author)

  10. Hole drift mobility in poly(hexylphenylsilane)

    International Nuclear Information System (INIS)

    Kunimi, Y.; Seki, S.; Tagawa, S.

    2000-01-01

    Poly(n-alkylphenylsilane)s in which n-alkyl were changed from methyl to octyl were polymerized. Hole transport properties of poly(alkyllphenylsilane)s were systematically studied by the DC time-of-flight (TOF) technique. While the hole drift mobility of poly(methylphenylsilane) increased monotonously in entire field, those of poly(hexylphenylsilane) and poly(octylphenylsilane) decreased with increase in the field strength. Temperature dependence of hole drift mobility in those polymers was small. On the basis of Baessler's disorder formalism the mobility was analyzed quantitatively to disserve complex contributions of charge transport. The analyzed results indicated that with increase in the length of n-alkyl side-groups, the energetic disorder of hopping sites became smaller and the disorder of distance between hopping sites became larger. These results were supported by the results obtained by UV absorption measurement and positron annihilation life-time spectroscopy measurement. (author)

  11. Poly(lactide)-containing multifunctional nanoparticles: Synthesis, domain-selective degradation and therapeutic applicability

    Science.gov (United States)

    Samarajeewa, Sandani

    Construction of nanoassemblies from degradable components is desired for packaging and controlled release of active therapeutics, and eventual biodegradability in vivo. In this study, shell crosslinked micelles composed of biodegradable poly(lactide) (PLA) core were prepared by the self-assembly of an amphiphilic diblock copolymer synthesized by a combination of ring opening polymerization (ROP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. Enzymatic degradation of the PLA cores of the nanoparticles was achieved upon the addition of proteinase K (PK). Kinetic analyses and comparison of the properties of the nanomaterials as a function of degradation extent will be discussed. Building upon our findings from selective-excavation of the PLA core, enzyme- and redox-responsive nanoparticles were constructed for the encapsulation and stimuli-responsive release of an antitumor drug. This potent chemotherapeutic, otherwise poorly soluble in water was dispersed into aqueous solution by the supramolecular co-assembly with an amphiphilic block copolymer, and the release from within the core of these nanoparticles were gated by crosslinking the hydrophilic shell region with a reduction-responsive crosslinker. Enzyme- and reduction-triggered release behavior of the antitumor drug was demonstrated along with their remarkably high in vitro efficacy. As cationic nanoparticles are a promising class of transfection agents for nucleic acid delivery, in the next part of the study, synthetic methodologies were developed for the conversion of the negatively-charged shell of the enzymatically-degradable shell crosslinked micelles to positively-charged cationic nanoparticles for the complexation of nucleic acids. These degradable cationic nanoparticles were found to efficiently deliver and transfect plasmid DNA in vitro. The hydrolysis of the PLA core and crosslinkers of the nanocarriers may provide a mechanism for their programmed disassembly within

  12. An approach to the construction of tailor-made amphiphilic peptides that strongly and selectively bind to hairpin RNA targets.

    Science.gov (United States)

    Lee, Su Jin; Hyun, Soonsil; Kieft, Jeffrey S; Yu, Jaehoon

    2009-02-18

    The hairpin RNA motif is one of the most frequently observed secondary structures and is often targeted by therapeutic agents. An amphiphilic peptide with seven lysine and eight leucine residues and its derivatives were designed for use as ligands against RNA hairpin motifs. We hypothesized that variations in both the hydrophobic leucine-rich and hydrophilic lysine-rich spheres of these amphiphilic peptides would create extra attractive interactions with hairpin RNA targets. A series of alanine-scanned peptides were probed to identify the most influential lysine residues in the hydrophilic sphere. The binding affinities of these modified peptides with several hairpins, such as RRE, TAR from HIV, a short hairpin from IRES of HCV, and a hairpin from the 16S A-site stem from rRNA, were determined. Since the hairpin from IRES of HCV was the most susceptible to the initial series of alanine-scanned peptides, studies investigating how further variations in the peptides effect binding employed the IRES hairpin. Next, the important Lys residues were substituted by shorter chain amines, such as ornithine, to place the peptide deeper into the hairpin groove. In a few cases, a 70-fold improved binding was observed for peptides that contained the specifically located shorter amine side chains. To further explore changes in binding affinities brought about by alterations in the hydrophobic sphere, tryptophan residues were introduced in place of leucine. A few peptides with tryptophan in specific positions also displayed 70-fold improved binding affinities. Finally, double mutant peptides incorporating both specifically located shorter amine side chains in the hydrophilic region and tryptophan residues in the hydrophobic region were synthesized. The binding affinities of peptides containing the simple double modification were observed to be 80 times lower, and their binding specificities were increased 40-fold. The results of this effort provide important information about

  13. Cationic Amphiphilic Tris-Cyclometalated Iridium(III) Complexes Induce Cancer Cell Death via Interaction with Ca2+-Calmodulin Complex.

    Science.gov (United States)

    Hisamatsu, Yosuke; Suzuki, Nozomi; Masum, Abdullah-Al; Shibuya, Ai; Abe, Ryo; Sato, Akira; Tanuma, Sei-Ichi; Aoki, Shin

    2017-02-15

    In our previous paper, we reported on the preparation of some cationic amphiphilic Ir complexes (2c, 2d) containing KKGG peptides that induce and detect cell death of Jurkat cells. Mechanistic studies suggest that 2c interacts with anionic molecules and/or membrane receptors on the cell surface to trigger an intracellular Ca 2+ response, resulting in the induction of cell death, accompanied by membrane disruption. We have continued the studies of cell death of Jurkat cells induced by 2c and found that xestospongin C, a selective inhibitor of an inositol 1,4,5-trisphosphate receptor located on the endoplasmic reticulum (ER), reduces the cytotoxicity of 2c, suggesting that 2c triggers the release of Ca 2+ from the ER, leading to an increase in the concentration of cytosolic Ca 2+ , thus inducing cell death. Moreover, we synthesized a series of new amphiphilic cationic Ir complexes 5a-c containing photoreactive 3-trifluoromethyl-3-phenyldiazirine (TFPD) groups, in an attempt to identify the target molecules of 2c. Interestingly, it was discovered that a TFPD group functions as a triplet quencher of Ir complexes. It was also found that 5b is useful as a turn-on phosphorescent probe of acidic proteins such as bovine serum albumin (BSA) (pI = 4.7) and their complexation was confirmed by luminescence titrations and SDS-PAGE of photochemical products between them. These successful results allowed us to carry out photoaffinity labeling of the target biomolecules of 5b (2c and analogues thereof) in Jurkat cells. A proteomic analysis of the products obtained by the photoirradiation of 5b with Jurkat cells suggests that the Ca 2+ -binding protein "calmodulin (CaM)" is one of target proteins of the Ir complexes. Indeed, 5b was found to interact with the Ca 2+ -CaM complex, as evidenced by luminescence titrations and the results of photochemical reactions of 5b with CaM in the presence of Ca 2+ (SDS-PAGE). A plausible mechanism for cell death induced by a cationic amphiphilic Ir

  14. Fabrication of conductive metallized nanostructures from self-assembled amphiphilic triblock copolymer templates: Nanospheres, nanowires, nanorings

    International Nuclear Information System (INIS)

    Zhu Jintao; Jiang Wei

    2007-01-01

    Various metallized nanostructures (such as rings, wires with controllable lengths, spheres) have been successfully fabricated by coating metallic nanolayers onto soft nanotemplates through simple electroless methods. In particular, bimetallic nanostructures have been obtained by using simple methods. The multiple functional polymeric nanostructures were obtained through the self-assembly of polystyrene/poly(4-vinyl pyridine) triblock copolymer (P4VP-b-PS-b-P4VP) in selective media by changing the common solvent properties. By combining field emission scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) characterization, it was confirmed that polymer/metal and bimetallic (Au at Ag) core-shell nanostructures could be achieved by chemical metal deposition method

  15. Cytotoxicity of Paclitaxel in biodegradable self-assembled core-shell poly(lactide-co-glycolide ethylene oxide fumarate) nanoparticles.

    Science.gov (United States)

    He, Xuezhong; Ma, Junyu; Mercado, Angel E; Xu, Weijie; Jabbari, Esmaiel

    2008-07-01

    Biodegradable core-shell polymeric nanoparticles (NPs), with a hydrophobic core and hydrophilic shell, are developed for surfactant-free encapsulation and delivery of Paclitaxel to tumor cells. Poly (lactide-co-glycolide fumarate) (PLGF) and Poly (lactide-fumarate) (PLAF) were synthesized by condensation polymerization of ultra-low molecular weight poly(L: -lactide-co-glycolide) (ULMW PLGA) with fumaryl chloride (FuCl). Similarly, poly(lactide-co-ethylene oxide fumarate) (PLEOF) macromer was synthesized by reacting ultra-low molecular weight poly(L: -lactide) (ULMW PLA) and PEG with FuCl. The blend PLGF/PLEOF and PLAF/PLEOF macromers were self-assembled into NPs by dialysis. The NPs were characterized with respect to particle size distribution, morphology, and loading efficiency. The physical state and miscibility of Paclitaxel in NPs were characterized by differential scanning calorimetry. Tumor cell uptake and cytotoxicity of Paclitaxel loaded NPs were measured by incubation with HCT116 human colon carcinoma cells. The distribution of NPs in vivo was assessed with Apc(Min/+)mouse using infrared imaging. PLEOF macromer, due to its amphiphilic nature, acted as a surface active agent in the process of self-assembly which produced core-shell NPs with PLGF/PLAF and PLEOF macromers as the core and shell, respectively. The encapsulation efficiency ranged from 70 to 56% and it was independent of the macromer but decreased with increasing concentration of Paclitaxel. Most of the PLGF and PLAF NPs degraded in 15 and 28 days, respectively, which demonstrated that the release was dominated by hydrolytic degradation and erosion of the matrix. As the concentration of Paclitaxel was increased from 0 to 10, and 40 mug/ml, the viability of HCT116 cells incubated with free Paclitaxel decreased from 100 to 65 and 40%, respectively, while those encapsulated in PLGF/PLEOF NPs decreased from 93 to 54 and 28%. Groups with Paclitaxel loaded NPs had higher cytotoxicity compared to

  16. Self-Assembling Peptide Amphiphiles for Therapeutic Delivery of Proteins, Drugs, and Stem Cells

    Science.gov (United States)

    Lee, Sungsoo Seth

    Biomaterials are used to help regenerate or replace the structure and function of damaged tissues. In order to elicit desired therapeutic responses in vivo, biomaterials are often functionalized with bioactive agents, such as growth factors, small molecule drugs, or even stem cells. Therefore, the strategies used to incorporate these bioactive agents in the microstructures and nanostructures of biomaterials can strongly influence the their therapeutic efficacy. Using self-assembling peptide amphiphiles (PAs), this work has investigated supramolecular nanostructures with improved interaction with three types of therapeutic agents: bone morphogenetic protein 2 (BMP-2) which promotes osteogenic differentiation and bone growth, anti-inflammatory drug naproxen which is used to treat osteo- and rheumatoid arthritis, and neural stem cells that could differentiate into neurons to treat neurodegenerative diseases. For BMP-2 delivery, two specific systems were investigated with affinity for BMP-2: 1) heparin-binding nanofibers that display the natural ligand of the osteogenic protein, and 2) nanofibers that display a synthetic peptide ligand discovered in our laboratory through phage display to directly bind BMP-2. Both systems promoted enhanced osteoblast differentiation of pluripotent C2C12 cells and augmented bone regeneration in two in vivo models, a rat critical-size femur defect model and spinal arthrodesis model. The thesis also describes the use of PA nanofibers to improve the delivery of the anti-inflammatory drug naproxen. To promote a controlled release, naproxen was chemically conjugated to the nanofiber surface via an ester bond that would only be cleaved by esterases, which are enzymes found naturally in the body. In the absence of esterases, the naproxen remained conjugated to the nanofibers and was non-bioactive. On the other hand, in the presence of esterases, naproxen was slowly released and inhibited cyclooxygenase-2 (COX-2) activity, an enzyme responsible

  17. Synthesis, physico-chemical properties and complexing abilities of new amphiphilic ligands from D-galacturonic acid.

    Science.gov (United States)

    Allam, Anas; Behr, Jean-Bernard; Dupont, Laurent; Nardello-Rataj, Véronique; Plantier-Royon, Richard

    2010-04-19

    This paper describes a convenient and efficient synthesis of new complexing surfactants from d-galacturonic acid and n-octanol as renewable raw materials in a two-step sequence. In the first step, simultaneous O-glycosidation-esterification under Fischer conditions was achieved. The anomeric ratio of the products was studied based on the main experimental parameters and the activation mode (thermal or microwave). In the second step, aminolysis of the n-octyl ester was achieved with various functionalized primary amines under standard thermal or microwave activation. The physico-chemical properties of these new amphiphilic ligands were measured and these compounds were found to exhibit interesting surface properties. Complexing abilities of one uronamide ligand functionalized with a pyridine moiety toward Cu(II) ions was investigated in solution by EPR titrations. A solid compound was also synthesized and characterized, its relative structure was deduced from spectroscopic data. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  18. Influence of additives (inorganic/organic on the clouding behavior of amphiphilic drug solutions: Some thermodynamic studies

    Directory of Open Access Journals (Sweden)

    Malik Abdul Rub

    2015-05-01

    Full Text Available Herein we provide a detailed result about the effect of various additives, viz. inorganic salts, quaternary ammonium bromides (QABs and amino acids on clouding behavior of amphiphilic drug amitriptyline hydrochloride (AMT. The continuous increase in the cloud point (CP of drug by increase in inorganic salt concentration and the magnitude of increases rely upon the position of the salts in Hofmeister series and hydrated radii. The QABs also influence continuous increase in the CP, which is illustrated in terms of the alkyl chain length of peculiar QAB. The effect of amino acids on CP of the drug solution is dependent upon the characteristics (acidic, basic, polar or nonpolar of particular amino acids. The overall behavior of additives has been analyzed and discussed on the basis of electrostatic repulsion or interaction, micellar growth, and mixed micelle formation between the ingredients. In addition to this, thermodynamic parameters are also evaluated.

  19. Preparation and structural characterisation of novel and versatile amphiphilic octenyl succinic anhydride-modified hyaluronic acid derivatives

    DEFF Research Database (Denmark)

    Eenschooten, Corinne Diane; Guillaumie, Fanny; Kontogeorgis, Georgios

    2010-01-01

    and structurally characterised by Fourier transform-infrared spectroscopy and proton nuclear magnetic resonance spectroscopy (1H NMR). The influence of four reaction parameters on the DS of the derivatives was studied by means of an experimental design. The results showed that the OSA/HA molar ratio, the buffer......The purpose of the present study was to prepare amphiphilic hyaluronic acid (HA) derivatives and to study the influence of a selection of reaction parameters on the degree of substitution (DS) of the derivatives. Octenyl succinic anhydride (OSA)–modified HA (OSA–HA) derivatives were prepared...... (NaHCO3) concentration and their interaction had the largest influence while the HA concentration and the reaction time only had a negligible effect. According to 1H NMR the maximum DS achieved within the experimental conditions tested was 43% per disaccharide unit. Moreover optimal reaction...

  20. Self-Assembly Behavior and pH-Stimuli-Responsive Property of POSS-Based Amphiphilic Block Copolymers in Solution

    Directory of Open Access Journals (Sweden)

    Yiting Xu

    2018-05-01

    Full Text Available Stimuli-responsive polymeric systems containing special responsive moieties can undergo alteration of chemical structures and physical properties in response to external stimulus. We synthesized a hybrid amphiphilic block copolymer containing methoxy polyethylene glycol (MePEG, methacrylate isobutyl polyhedral oligomeric silsesquioxane (MAPOSS and 2-(diisopropylaminoethyl methacrylate (DPA named MePEG-b-P(MAPOSS-co-DPA via atom transfer radical polymerization (ATRP. Spherical micelles with a core-shell structure were obtained by a self-assembly process based on MePEG-b-P(MAPOSS-co-DPA, which showed a pH-responsive property. The influence of hydrophobic chain length on the self-assembly behavior was also studied. The pyrene release properties of micelles and their ability of antifouling were further studied.

  1. Nanofluid of graphene-based amphiphilic Janus nanosheets for tertiary or enhanced oil recovery: High performance at low concentration.

    Science.gov (United States)

    Luo, Dan; Wang, Feng; Zhu, Jingyi; Cao, Feng; Liu, Yuan; Li, Xiaogang; Willson, Richard C; Yang, Zhaozhong; Chu, Ching-Wu; Ren, Zhifeng

    2016-07-12

    The current simple nanofluid flooding method for tertiary or enhanced oil recovery is inefficient, especially when used with low nanoparticle concentration. We have designed and produced a nanofluid of graphene-based amphiphilic nanosheets that is very effective at low concentration. Our nanosheets spontaneously approached the oil-water interface and reduced the interfacial tension in a saline environment (4 wt % NaCl and 1 wt % CaCl2), regardless of the solid surface wettability. A climbing film appeared and grew at moderate hydrodynamic condition to encapsulate the oil phase. With strong hydrodynamic power input, a solid-like interfacial film formed and was able to return to its original form even after being seriously disturbed. The film rapidly separated oil and water phases for slug-like oil displacement. The unique behavior of our nanosheet nanofluid tripled the best performance of conventional nanofluid flooding methods under similar conditions.

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

    Science.gov (United States)

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

    2016-08-01

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

  3. Impact of amphiphilic molecules on the structure and stability of homogeneous sphingomyelin bilayer: Insights from atomistic simulations

    Science.gov (United States)

    Kumari, Pratibha; Kaur, Supreet; Sharma, Shobha; Kashyap, Hemant K.

    2018-04-01

    Modulation of lipid membrane properties due to the permeation of amphiphiles is an important biological process pertaining to many applications in the field of pharmaceutics, toxicology, and biotechnology. Sphingolipids are both structural and functional lipids that constitute an important component of mechanically stable and chemically resistant outer leaflets of plasma membranes. Here, we present an atomistic molecular dynamics simulation study to appreciate the concentration-dependent effects of small amphiphilic molecules, such as ethanol, acetone, and dimethyl sulfoxide (DMSO), on the structure and stability of a fully hydrated homogeneous N-palmitoyl-sphingomyelin (PSM) bilayer. The study reveals an increase in the lateral expansion of the bilayer along with disordering of the hydrophobic lipid tails on increasing the concentration of ethanol. At higher concentrations of ethanol, rupturing of the bilayer is quite evident through the analysis of partial electron density profiles and lipid tail order parameters. For ethanol containing systems, permeation of water molecules in the hydrophobic part of the bilayer is allowed through local defects made due to the entry of ethanol molecules via ethanol-ethanol and ethanol-PSM hydrogen bonds. Moreover, the extent of PSM-PSM hydrogen bonding decreases with increasing ethanol concentration. On the other hand, acetone and DMSO exhibit minimal effects on the stability of the PSM bilayer at their lower concentrations, but at higher concentrations they tend to enhance the stability of the bilayer. The simulated potential of mean force (PMF) profiles for the translocation of the three solutes studied reveal that the free-energy of transfer of an ethanol molecule across the PSM lipid head region is lower than that for acetone and DMSO molecules. However, highest free-energy rise in the core hydrophobic part of the bilayer is observed for the DMSO molecule, whereas the ethanol and acetone PMF profiles show a lower barrier in

  4. Preparation, Characterization and Permeation Behavior of Poly(methyl acrylate-Poly(dimethyl siloxane-Poly(methyl acrylate Block Copolymer/Poly(vinyl acetate Blend Membranes

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Semsarzadeh

    2015-03-01

    Full Text Available Structure of polymeric materials is of the most important factors in determination of the characteristics and properties of the membranes. Various research and developments on polymeric membranes confirm the direct correlation between structure-properties of polymeric membranes. In this research, the structural outcome of poly(methyl acrylate-poly(dimethyl siloxane-poly(methyl acrylate/poly(vinyl acetate blend membranes and its relationship with gas permeation behavior of the blends were investigated. The flexible block copolymer of poly(methyl acrylate-poly(dimethyl siloxane-poly(methyl acrylate (PMA-PDMS-PMA was synthesized via atom transfer radical polymerization. Morphology and chemical structure of the synthesized block copolymer was investigated by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, gel permeation chromatography, X-ray diffraction analysis, differential scanning calorimetry and scanning electron microscopy. Blend membranes of PMA-PDMS-PMA and poly(vinyl acetate (PVAc were prepared by solution casting method in different compositions. By adding poly(vinyl acetate to PMA-PDMS-PMA block copolymer, the selectivity of the membranes for carbon dioxide/methane pair gases were increased by 55%. Fractional free volume (an indication of chain packing efficiency in blend membranes and dielectric constant (an indication of the molar volume and molar polarization of the blend membranes were obtained as the factors reflected the microstructural effect of PMA-PDMS-PMA and PVAc blend membranes. The efforts were directed toward expressing more precise structure-properties relationship of PMA-PDMS-PMA/PVAc blend membranes. The experimental permeability values of the blend membranes reported in this research were compared with the modified logarithmic model. The modified logarithmic model was evaluated for other blend membranes.

  5. Polaron Hopping in Nano-scale Poly(dA–Poly(dT DNA

    Directory of Open Access Journals (Sweden)

    Singh Mahi

    2010-01-01

    Full Text Available Abstract We investigate the current–voltage relationship and the temperature-dependent conductance of nano-scale samples of poly(dA–poly(dT DNA molecules. A polaron hopping model has been used to calculate the I–V characteristic of nano-scale samples of DNA. This model agrees with the data for current versus voltage at temperatures greater than 100 K. The quantities G 0 , i 0 , and T 1d are determined empirically, and the conductivity is estimated for samples of poly(dA–poly(dT.

  6. Poly(ester-anhydride):poly(beta-amino ester) micro- and nanospheres: DNA encapsulation and cellular transfection.

    Science.gov (United States)

    Pfeifer, Blaine A; Burdick, Jason A; Little, Steve R; Langer, Robert

    2005-11-04

    Poly(ester-anhydride) delivery devices allow flexibility regarding carrier dimensions (micro- versus nanospheres), degradation rate (anhydride versus ester hydrolysis), and surface labeling (through the anhydride functional unit), and were therefore tested for DNA encapsulation and transfection of a macrophage P388D1 cell line. Poly(l-lactic acid-co-sebacic anhydride) and poly(l-lactic acid-co-adipic anhydride) were synthesized through melt condensation, mixed with 25 wt.% poly(beta-amino ester), and formulated with plasmid DNA (encoding firefly luciferase) into micro- and nanospheres using a double emulsion/solvent evaporation technique. The micro- and nanospheres were then characterized (size, morphology, zeta potential, DNA release) and assayed for DNA encapsulation and cellular transfection over a range of poly(ester-anhydride) copolymer ratios. Poly(ester-anhydride):poly(beta-amino ester) composite microspheres (6-12 microm) and nanospheres (449-1031 nm), generated with copolymers containing between 0 and 25% total polyanhydride content, encapsulated plasmid DNA (>or=20% encapsulation efficiency). Within this polyanhydride range, poly(adipic anhydride) copolymers provided DNA encapsulation at an increased anhydride content (10%, microspheres; 10-25%, nanospheres) compared to poly(sebacic anhydride) copolymers (1%, microspheres and nanospheres) with cellular transfection correlating with the observed DNA encapsulation.

  7. Poly-thiosemicarbazide membrane for gold recovery

    KAUST Repository

    Villalobos, Luis Francisco; Yapici, Tahir; Peinemann, Klaus-Viktor

    2014-01-01

    A novel polymeric membrane adsorber with a high density of adsorption sites that can selectively capture Au(III) ions, is proposed as an efficient alternative to recover gold from dilute solutions. Poly-thiosemicarbazide (PTSC), a polymer

  8. Lignin poly(lactic acid) copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Johan Vilhelm; Chung, Yi-Lin; Li, Russell Jingxian; Waymouth, Robert; Sattely, Elizabeth; Billington, Sarah; Frank, Curtis W.

    2017-02-14

    Provided herein are graft co-polymers of lignin and poly(lactic acid) (lignin-g-PLA copolymer), thermoset and thermoplastic polymers including them, methods of preparing these polymers, and articles of manufacture including such polymers.

  9. Thromboresistance of functionalized poly(methylmethacrylate): the ...

    Indian Academy of Sciences (India)

    Thrombogenicity; functional group; poly(methylmethacrylate); surface charge; sulphonate. 1. Introduction ... proteins.2 Thus, the interaction of a polymer with the blood results into the .... adsorption process due to its electrostatic forces. 4.

  10. Hydrophobically modified inulin as an amphiphilic carbohydrate polymer for micellar delivery of paclitaxel for intravenous route.

    Science.gov (United States)

    Muley, Pratik; Kumar, Sunny; El Kourati, Fadoua; Kesharwani, Siddharth S; Tummala, Hemachand

    2016-03-16

    Micellization offers several advantages for the delivery of water insoluble drugs including a nanoparticulate 'core-shell' delivery system for drug targeting. Recently, hydrophobically modified polysaccharides (HMPs) are gaining recognition as micelle forming polymers to encapsulate hydrophobic drugs. In this manuscript, for the first time, we have evaluated the self-assembling properties of a lauryl carbamate derivative of the poly-fructose natural polymer inulin (Inutec SP1(®) (INT)) to form paclitaxel (PTX) loaded micelles. INT self-assembled into well-defined micellar structures in aqueous environment with a low critical micellar concentration of 27.8 μg/ml. INT micelles exhibited excellent hemocompatibility and low toxicity to cultured cells. PTX loaded INT micelles exhibited a mean size of 256.37 ± 10.45 nm with excellent drug encapsulation efficiency (95.66 ± 2.25%) and loading (8.69 ± 0.22%). PTX loaded micelles also displayed sustained release of PTX and enhanced anti-cancer efficacy in-vitro in mouse melanoma cells (B16F10) compared to Taxol formulation with Cremophor EL as solvent. In addition, PTX loaded INT micelles exhibited comparable in-vivo antitumor activity in B16F10 allograft mouse model at half the dose of Taxol. In conclusion, INT offers safe, inexpensive and natural alternative to widely used PEG-modified polymers for the formulation of micellar delivery systems for paclitaxel. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Control over Structure and Function of Peptide Amphiphile Supramolecular Assemblies through Molecular Design and Energy Landscapes

    Science.gov (United States)

    Tantakitti, Faifan

    Supramolecular chemistry is a powerful tool to create a material of a defined structure with tunable properties. This strategy has led to catalytically active, bioactive, and environment-responsive materials, among others, that are valuable in applications ranging from sensor technology to energy and medicine. Supramolecular polymers formed by peptide amphiphiles (PAs) have been especially relevant in tissue regeneration due to their ability to form biocompatible structures and mimic many important signaling molecules in biology. These supramolecular polymers can form nanofibers that create networks which mimic natural extracellular matrices. PA materials have been shown to induce growth of blood vessels, bone, cartilage, and nervous tissue, among others. The work described in this thesis not only studied the relationship between molecular structure and functions of PA assemblies, but also uncovered a powerful link between the energy landscape of their supramolecular self-assembly and the ability of PA materials to interact with cells. In chapter 2, it is argued that fabricating fibrous nanostructures with defined mechanical properties and decoration with bioactive molecules is not sufficient to create a material that can effectively communicate with cells. By systemically placing the fibronectin-derived RGDS epitope at increasing distances from the surface of PA nanofibers through a linker of one to five glycine residues, integrin-mediated RGDS signaling was enhanced. The results suggested that the spatial presentation of an epitope on PA nanofibers strongly influences the bioactivity of the PA substrates. In further improving functionality of a PA-based scaffold to effectively direct cell growth and differentiation, chapter 3 explored the use of a cell microcarrier to compartmentalize and simultaneously tune insoluble and soluble signals in a single matrix. PA nanofibers were incorporated at the surface of the microcarrier in order to promote cell adhesion, while

  12. New Linear and Star-Shaped Thermogelling Poly([R]-3-hydroxybutyrate) Copolymers.

    Science.gov (United States)

    Barouti, Ghislaine; Liow, Sing Shy; Dou, Qingqing; Ye, Hongye; Orione, Clément; Guillaume, Sophie M; Loh, Xian Jun

    2016-07-18

    The synthesis of multi-arm poly([R]-3-hydroxybutyrate) (PHB)-based triblock copolymers (poly([R]-3-hydroxybutyrate)-b-poly(N-isopropylacrylamide)-b-[[poly(methyl ether methacrylate)-g-poly(ethylene glycol)]-co-[poly(methacrylate)-g-poly(propylene glycol)

  13. Mechanical properties of a waterborne pressure-sensitive adhesive with a percolating poly(acrylic acid)-based diblock copolymer network: effect of pH.

    Science.gov (United States)

    Gurney, Robert S; Morse, Andrew; Siband, Elodie; Dupin, Damien; Armes, Steven P; Keddie, Joseph L

    2015-06-15

    Copolymerizing an acrylic acid comonomer is often beneficial for the adhesive properties of waterborne pressure-sensitive adhesives (PSAs). Here, we demonstrate a new strategy in which poly(acrylic acid) (PAA) is distributed as a percolating network within a PSA film formed from a polymer colloid. A diblock copolymer composed of PAA and poly(n-butyl acrylate) (PBA) blocks was synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization and adsorbed onto soft acrylic latex particles prior to their film formation. The thin adsorbed shells on the particles create a percolating network that raises the elastic modulus, creep resistance and tensile strength of the final film. When the film formation occurs at pH 10, ionomeric crosslinking occurs, and high tack adhesion is obtained in combination with high creep resistance. The results show that the addition of an amphiphilic PAA-b-PBA diblock copolymer (2.0 wt.%) to a soft latex provides a simple yet effective means of adjusting the mechanical and adhesive properties of the resulting composite film. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. A Piriápolis

    Directory of Open Access Journals (Sweden)

    Luis Alberto Quijano Alpuin

    2013-11-01

    Full Text Available Es Piriápolis una estrella prodigiosa que del cielo una noche se escapó, y escondiendo su estela luminosa entre el mar y la sierra se ocultó.   Forjador de ilusiones y de sueños, solo Piria soñando lo encontró, mas no es suyo a pesar de ser su dueño a nosotros su sueño nos legó.   Como él quisiera contemplarlo y mirarlo igual que él lo miró, a su espíritu quisiera yo pasearlo y a su sueño llevarlo entre los dos.   Recoger las horas de los desalientos y en una mochila poderlo llevar, y sobre las rocas ir dejando al viento las desiluciones que puedan quedar.   Llenarme los ojos de color y espuma gozar en la playa con él al pasar, el gris de la sierra tras la blanca bruma el azul del cielo y el verde del mar.   Luis Alberto Quijano Alpuin (1937- Poeta y folklorista uruguayo

  15. Prediction of Poly(A Sites by Poly(A Read Mapping.

    Directory of Open Access Journals (Sweden)

    Thomas Bonfert

    Full Text Available RNA-seq reads containing part of the poly(A tail of transcripts (denoted as poly(A reads provide the most direct evidence for the position of poly(A sites in the genome. However, due to reduced coverage of poly(A tails by reads, poly(A reads are not routinely identified during RNA-seq mapping. Nevertheless, recent studies for several herpesviruses successfully employed mapping of poly(A reads to identify herpesvirus poly(A sites using different strategies and customized programs. To more easily allow such analyses without requiring additional programs, we integrated poly(A read mapping and prediction of poly(A sites into our RNA-seq mapping program ContextMap 2. The implemented approach essentially generalizes previously used poly(A read mapping approaches and combines them with the context-based approach of ContextMap 2 to take into account information provided by other reads aligned to the same location. Poly(A read mapping using ContextMap 2 was evaluated on real-life data from the ENCODE project and compared against a competing approach based on transcriptome assembly (KLEAT. This showed high positive predictive value for our approach, evidenced also by the presence of poly(A signals, and considerably lower runtime than KLEAT. Although sensitivity is low for both methods, we show that this is in part due to a high extent of spurious results in the gold standard set derived from RNA-PET data. Sensitivity improves for poly(A sites of known transcripts or determined with a more specific poly(A sequencing protocol and increases with read coverage on transcript ends. Finally, we illustrate the usefulness of the approach in a high read coverage scenario by a re-analysis of published data for herpes simplex virus 1. Thus, with current trends towards increasing sequencing depth and read length, poly(A read mapping will prove to be increasingly useful and can now be performed automatically during RNA-seq mapping with ContextMap 2.

  16. How To Tackle the Issues in Free Energy Simulations of Long Amphiphiles Interacting with Lipid Membranes: Convergence and Local Membrane Deformations

    DEFF Research Database (Denmark)

    Filipe, H. A. L.; Moreno, M. J.; Rog, T.

    2014-01-01

    One of the great challenges in membrane biophysics is to find a means to foster the transport of drugs across complex membrane structures. In this spirit, we elucidate methodological challenges associated with free energy computations of complex chainlike molecules across lipid membranes....... As an appropriate standard molecule to this end, we consider 7-nitrobenz-2-oxa-1,3-diazol-4-yl-labeled fatty amine, NBD-C-n, which is here dealt with as a homologous series with varying chain lengths. We found the membrane-water interface region to be highly sensitive to details in free energy computations. Despite...... of radius 1.7 nm from the amphiphile. Importantly, the free energy results given by PGC were found to be qualitatively consistent with experimental data, while the PGD results were not. We conclude that with long amphiphiles there is reason for concern with regard to computations of their free energy...

  17. Inclusion Complexes of a New Family of Non-Ionic Amphiphilic Dendrocalix[4]arene and Poorly Water-Soluble Drugs Naproxen and Ibuprofen

    Directory of Open Access Journals (Sweden)

    Khalid Khan

    2017-05-01

    Full Text Available The inclusion complexes of a new family of nonionic amphiphilic calix[4]arenes with the anti-inflammatory hydrophobic drugs naproxen (NAP and ibuprofen (IBP were investigated. The effects of the alkyl chain’s length and the inner core of calix[4]arenes on the interaction of the two drugs with the calix[4]arenes were explored. The inclusion complexes of Amphiphiles 1a–c with NAP and IBP increased the solubility of these drugs in aqueous media. The interaction of 1a–c with the drugs in aqueous media was investigated through fluorescence, molecular modeling, and 1H-NMR analysis. TEM studies further supported the formation of inclusion complexes. The length of lipophilic alkyl chains and the intrinsic cyclic nature of cailx[4]arene derivatives 1a–c were found to have a significant impact on the solubility of NAP and IBP in pure water.

  18. Ion-specific weak adsorption of salts and water/octanol transfer free energy of a model amphiphilic hexa-peptide

    International Nuclear Information System (INIS)

    Dejugnat, Ch.; Dufreche, J.F.; Zemb, Th.; Dejugnat, Ch.

    2011-01-01

    An amphiphilic hexa-peptide has been used as a model to quantify how specific ion effects induced by addition of four salts tune the hydrophilic/hydrophobic balance and induce temperature-dependant coacervate formation from aqueous solution. The hexa-peptide chosen is present as a dimer with low transfer energy from water to octanol. Taking sodium chloride as the reference state in the Hofmeister scale, we identify water activity effects and therefore measure the free energy of transfer from water to octanol and separately the free energy associated to the adsorption of chaotropic ions or the desorption of kosmotropic ions for the same amphiphilic peptide. These effects have the same order of magnitude: therefore, both energies of solvation as well as transfer into octanol strongly depend on the nature of the electrolytes used to formulate any buffer. Model peptides could be used on separation processes based on criteria linked to 'Hofmeister' but different from volume and valency. (authors)

  19. An organosilane-directed growth-induced etching strategy for preparing hollow/yolk–shell mesoporous organosilica nanospheres with perpendicular mesochannels and amphiphilic frameworks

    KAUST Repository

    Zou, Houbing

    2014-06-27

    We have developed an organosilane-directed growth-induced etching strategy to prepare hollow periodic mesoporous organosilica (PMO) nanospheres with perpendicular mesoporous channels and a clear hollow interior as well as an amphiphilic framework. This facile strategy is simple, efficient, and highly controllable. Silica nanospheres were utilized as hard templates to obtain hollow PMO nanospheres through a one-step route, with the structure parameter highly controlled by adjusting the synthesis conditions. Different organosilanes were used to obtain bridged hollow PMO nanospheres of different organic groups and showed different directed capacities. The integrity of the bridged organic group was confirmed by Fourier-transform infrared (FT-IR) spectroscopy and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Transmission electron microscopy (TEM) observations showed that the growth of the PMO shell and the dissolution of the silica nanosphere core occurred simultaneously for each nanosphere, while 29Si NMR spectra revealed that the dissolved silica species from the silica nanospheres transformed into PMO shells by co-condensation with hydrolyzed organosilane oligomers. As a result, the obtained hollow nanospheres were amphiphilic, which can even be used as a particle emulsifier for O-W or W-O emulsion in various systems. These materials can also be served as an efficient sorbent for removal of hydrophobic contaminants in water. Using the proposed formation mechanism, this strategy can be extended to transform silica-coated composite materials into yolk-shell structures with a functional interior core and a perpendicular mesoporous amphiphilic shell. As a nanoreactor, the -Ph- bridged amphiphilic shell showed a faster diffusion rate for organic reactants in water than the hydrophilic silica shell, and thus better catalytic activity for reduction of 4-nitrophenol. This journal is © the Partner Organisations 2014.

  20. Phase behavior of fluorocarbon and hydrocarbon double-chain hydroxylated and galactosylated amphiphiles and bolaamphiphiles. Long-term shelf-stability of their liposomes.

    Science.gov (United States)

    Clary, L; Gadras, C; Greiner, J; Rolland, J P; Santaella, C; Vierling, P; Gulik, A

    1999-06-01

    This paper describes the morphological characterization, by freeze-fracture electron microscopy, and the thermotropic phase behavior, by differential scanning calorimetry and/or X-ray scattering, of aqueous dispersions of various hydroxylated and galactosylated double-chain amphiphiles and bolaamphiphiles, several of them containing one or two hydrophobic fluorocarbon chains. Colloidal systems are observed in water with the hydroxylated hydrocarbon or fluorocarbon bolaamphiphiles only when they are dispersed with a co-amphiphile such as rac-1,2-dimyristoylphosphatidylcholine (DMPC) or rac-1,2-distearoylphosphatidylcholine (DSPC). Liposomes are formed providing the relative content of bolaamphiphiles does not exceed 20% mol. Most of these liposomes can be thermally sterilized and stored at room temperature for several months without any significant modification of their size and size distribution. The hydrocarbon galactosylated bolaamphiphile HO[C24][C12]Gal forms in water a lamellar phase (the gel to liquid-crystal phase transition is complete at 45 degrees C) and a Im3m cubic phase above 47 degrees C. The fluorocarbon HO[C24][F6C5]Gal analog displays a more complex and metastable phase behavior. The fluorinated non-bolaform galactosylated [F8C7][C16]AEGal and SerGal amphiphiles form lamellar phases in water. Low amounts (10% molar ratio) of the HO[C24][F6C5]Gal or HO[C24][C12]Gal bolaamphiphiles or of the single-headed [F8C7][C16]AEGal improve substantially the shelf-stability of reference phospholipon/cholesterol 2/1 liposomes. These liposomes when co-formulated with a single-headed amphiphile from the SerGal series are by far less stable.

  1. Effects of solubilization of short and medium-chain molecules in the self-assembly of two amphiphilic drugs in solution

    International Nuclear Information System (INIS)

    Barbosa, Silvia; Cheema, Mohammad Arif; Siddiq, Mohammad; Taboada, Pablo; Mosquera, Victor

    2009-01-01

    The effect of short and medium chain length alcohols ethanol, propanol, and butanol on the thermodynamic properties of aqueous solutions of the ionic amphiphilic antidepressants imipramine and clomipramine hydrochlorides has been investigated at T = 293 K. Critical concentrations of the drugs were obtained from ultrasound velocity measurements. Experimental results have shown a strong dependence of the ultrasound velocity with the alcohol concentration and chain length. Differences in the aggregate properties of both amphiphiles arise from the presence of the extra Cl - substituent on the ring system of clomipramine. Density and ultrasound measurements have been used to obtain the apparent molar volumes, V φ , and isentropic apparent molar compressibilities, K φ(S) , for the aqueous drug/water-alcohol solutions. The distribution coefficient of the amount solubilized between water and the aggregates, K, has been determined using an indirect method based on the pseudo-phase model by using apparent molar volume values. This method allows the calculation of the distribution coefficients at concentrations below saturation. The standard molar Gibbs free energy change on transfer from the aqueous to the micellar, ΔG 0 , phase was calculated from the partition coefficient. The results have highlighted the structural differences between both amphiphiles

  2. Tipping the Scale from Disorder to Alpha-helix: Folding of Amphiphilic Peptides in the Presence of Macroscopic and Molecular Interfaces.

    Science.gov (United States)

    Dalgicdir, Cahit; Globisch, Christoph; Peter, Christine; Sayar, Mehmet

    2015-08-01

    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 disorder in solution. Consequently, their conformational preference is particularly susceptible to environmental conditions such as pH, salts, or presence of interfaces. In this study we use molecular dynamics simulations to analyze the conformational behavior of two synthetic peptides, LKKLLKLLKKLLKL (LK) and EAALAEALAEALAE (EALA), with built-in secondary amphiphilicity upon forming an alpha-helix. We use these model peptides to systematically study their aggregation and the influence of macroscopic and molecular interfaces on their conformational preferences. We show that the peptides are neither random coils in bulk water nor fully formed alpha helices, but adopt multiple conformations and secondary structure elements with short lifetimes. These provide a basis for conformation-selection and population-shift upon environmental changes. Differences in these peptides' response to macroscopic and molecular interfaces (presented by an aggregation partner) can be linked to their inherent alpha-helical tendencies in bulk water. We find that the peptides' aggregation behavior is also strongly affected by presence or absence of an interface, and rather subtly depends on their surface charge and hydrophobicity.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-14

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

  4. Tipping the Scale from Disorder to Alpha-helix: Folding of Amphiphilic Peptides in the Presence of Macroscopic and Molecular Interfaces.

    Directory of Open Access Journals (Sweden)

    Cahit Dalgicdir

    2015-08-01

    Full Text Available 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 disorder in solution. Consequently, their conformational preference is particularly susceptible to environmental conditions such as pH, salts, or presence of interfaces. In this study we use molecular dynamics simulations to analyze the conformational behavior of two synthetic peptides, LKKLLKLLKKLLKL (LK and EAALAEALAEALAE (EALA, with built-in secondary amphiphilicity upon forming an alpha-helix. We use these model peptides to systematically study their aggregation and the influence of macroscopic and molecular interfaces on their conformational preferences. We show that the peptides are neither random coils in bulk water nor fully formed alpha helices, but adopt multiple conformations and secondary structure elements with short lifetimes. These provide a basis for conformation-selection and population-shift upon environmental changes. Differences in these peptides' response to macroscopic and molecular interfaces (presented by an aggregation partner can be linked to their inherent alpha-helical tendencies in bulk water. We find that the peptides' aggregation behavior is also strongly affected by presence or absence of an interface, and rather subtly depends on their surface charge and hydrophobicity.

  5. BRCAA1 antibody- and Her2 antibody-conjugated amphiphilic polymer engineered CdSe/ZnS quantum dots for targeted imaging of gastric cancer

    Science.gov (United States)

    Li, Chao; Ji, Yang; Wang, Can; Liang, Shujing; Pan, Fei; Zhang, Chunlei; Chen, Feng; Fu, Hualin; Wang, Kan; Cui, Daxiang

    2014-05-01

    Successful development of safe and highly effective nanoprobes for targeted imaging of in vivo early gastric cancer is a great challenge. Herein, we choose the CdSe/ZnS (core-shell) quantum dots (QDs) as prototypical materials, synthesized one kind of a new amphiphilic polymer including dentate-like alkyl chains and multiple carboxyl groups, and then used the prepared amphiphilic polymer to modify QDs. The resultant amphiphilic polymer engineered QDs (PQDs) were conjugated with BRCAA1 and Her2 monoclonal antibody, and prepared BRCAA1 antibody- and Her2 antibody-conjugated QDs were used for in vitro MGC803 cell labeling and in vivo targeted imaging of gastric cancer cells. Results showed that the PQDs exhibited good water solubility, strong photoluminescence (PL) intensity, and good biocompatibility. BRCAA1 antibody- and Her2 antibody-conjugated QD nanoprobes successfully realized targeted imaging of in vivo gastric cancer MGC803 cells. In conclusion, BRCAA1 antibody- and Her2 antibody-conjugated PQDs have great potential in applications such as single cell labeling and in vivo tracking, and targeted imaging and therapeutic effects' evaluation of in vivo early gastric cancer cells in the near future.

  6. Flat-on ambipolar triphenylamine/C60 nano-stacks formed from the self-organization of a pyramid-sphere-shaped amphiphile.

    Science.gov (United States)

    Liang, Wei-Wei; Huang, Chi-Feng; Wu, Kuan-Yi; Wu, San-Lien; Chang, Shu-Ting; Cheng, Yen-Ju; Wang, Chien-Lung

    2016-04-21

    A giant amphiphile, which is constructed with an amorphous nano-pyramid (triphenylamine, TPA) and a crystalline nano-sphere (C 60 ), was synthesized. Structural characterization indicates that this pyramid-sphere-shaped amphiphile ( TPA-C 60 ) forms a solvent-induced ordered phase, in which the two constituent units self-assemble into alternating stacks of two-dimensional (2D) TPA and C 60 nano-sheets. Due to the complexity of the molecular structure and the amorphous nature of the nano-pyramid, phase formation was driven by intermolecular C 60 -C 60 interactions and the ordered phase could not be reformed from the TPA-C 60 melt. Oriented crystal arrays of TPA-C 60 , which contain flat-on TPA/C 60 nano-stacks, can be obtained via a PDMS-assisted crystallization (PAC) technique. The flat-on dual-channel supramolecular structure of TPA-C 60 delivered ambipolar and balanced charge-transport characteristics with an average μ e of 2.11 × 10 -4 cm 2 V -1 s -1 and μ h of 3.37 × 10 -4 cm 2 V -1 s -1 . The anisotropic charge-transport ability of the pyramid-sphere-shaped amphiphile was further understood based on the lattice structure and the lattice orientation of TPA-C 60 revealed from electron diffraction analyses.

  7. Gd-DTPA-Dopamine-Bisphytanyl Amphiphile: Synthesis, Characterisation and Relaxation Parameters of the Nanoassemblies and Their Potential as MRI Contrast Agents.

    Science.gov (United States)

    Gupta, Abhishek; Willis, Scott A; Waddington, Lynne J; Stait-Gardner, Tim; de Campo, Liliana; Hwang, Dennis W; Kirby, Nigel; Price, William S; Moghaddam, Minoo J

    2015-09-28

    Here, a new amphiphilic magnetic resonance imaging (MRI) contrast agent, a Gd(III)-chelated diethylenetriaminepentaacetic acid conjugated to two branched alkyl chains via a dopamine spacer, Gd-DTPA-dopamine-bisphytanyl (Gd-DTPA-Dop-Phy), which is readily capable of self-assembling into liposomal nanoassemblies upon dispersion in an aqueous solution, is reported. In vitro relaxivities of the dispersions were found to be much higher than Magnevist, a commercially available contrast agent, at 0.47 T but comparable at 9.40 T. Analysis of variable temperature (17)O NMR transverse relaxation measurements revealed the water exchange of the nanoassemblies to be faster than that previously reported for paramagnetic liposomes. Molecular reorientation dynamics were probed by (1)H NMRD profiles using a classical inner and outer sphere relaxation model and a Lipari-Szabo "model-free" approach. High payloads of Gd(III) ions in the liposomal nanoassemblies made solely from the Gd-DTPA-Dop-Phy amphiphiles, in combination with slow molecular reorientation and fast water exchange makes this novel amphiphile a suitable candidate to be investigated as an advanced MRI contrast agent. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Gas-permeation properties of poly(ethylene oxide) poly(butylene terephthalate block copolymers

    NARCIS (Netherlands)

    Metz, S.J.; Mulder, M.H.V.; Wessling, Matthias

    2004-01-01

    This paper reports the gas-permeation properties of poly(ethylene oxide) (PEO) poly(butylene terephthalate) (PBT) segmented multiblock copolymers. These block copolymers allow a precise structural modification by the amount of PBT and the PEO segment length, enabling a systematic study of the

  9. Poly(N-isopropylacrylamide)–poly(ferrocenylsilane) dual-responsive hydrogels: synthesis, characterization and antimicrobial applications

    NARCIS (Netherlands)

    Sui, Xiaofeng; Feng, Xueling; Di Luca, Andrea; van Blitterswijk, Clemens; Moroni, Lorenzo; Hempenius, Mark A.; Vancso, Gyula J.

    2013-01-01

    Novel hydrogels composed of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and redox-responsive poly(ferrocenylsilane) (PFS) macromolecules were formed by photopolymerization. PFS chains bearing acrylate side groups were copolymerized with NIPAM and N,N′-methylenebisacrylamide in

  10. Poly(aniline-co-m-aminobenzoic acid) deposited on poly(vinyl ...

    Indian Academy of Sciences (India)

    Abstract. In this work, we have deposited poly(aniline-co-m-aminobenzoic acid) on poly(vinyl alcohol) (PVA) by in situ ... along the polyaniline (PANI) chain results in self dop- ing of PANI and ..... The value of electrical conductivity is found to be ...

  11. Preparation of mono-dispersed silver nanoparticles assisted by chitosan-g-poly(ε-caprolactone) micelles and their antimicrobial application

    Energy Technology Data Exchange (ETDEWEB)

    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); Zhang, Huan [State Key Laboratory of Bioreactor Engineering, New World Biotechnology Institute, 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)

    2014-05-01

    Graphical abstract: - Highlights: • Chemical modification of chitosan were conducted after phthaloyl protection of amino groups. • Silver nanoparticles were prepared in the presence of chitosan-based copolymer micelles. • The optimal time scale and weight ratios of silver to micelles were monitored by UV–vis spectrometer. - Abstract: Amphiphilic chitosan-graft-poly(ε-caprolactone) (CS-g-PCLs) copolymers were synthesized by a homogeneous coupling method and characterized by {sup 1}H NMR, FTIR and ninhydrin assay. The graft copolymers were subsequently self-assembled into micelles, which were measured by DLS and TEM. The particle size of the micelles decreased as the segment grafting fraction was increased. Thereafter, silver nanoparticles were prepared in the presence of chitosan-based micelles under UV irradiation. The molar ratio and radiation time of silver to micelles were optimized with process monitored via UV–vis spectrophotometer. DLS and TEM were used to illustrate the particle structure and size while XRD patterns were applied to characterize the crystal structures of polymer-assisted silver nanoparticles. Films impregnated with silver nanoparticles were conducted with results of strong antimicrobial activities against Escherichia coli and Staphylococcus aureus as model Gram-negative and positive bacteria.

  12. Characterization and photoconductivity study of well-defined C60 terminated poly(tert-butyl acrylate-b-styrene)

    International Nuclear Information System (INIS)

    Yang Dong; Li Lang; Wang Changchun

    2004-01-01

    Atom transfer radical polymerization (ATRP) catalyzed by N,N',N',N'',N''-pentamethyldiethylenetriamine (PMDETA)/CuBr was performed to synthesize poly (tert-butyl acrylate) (PtBA-Br) with predesigned molecular weight and narrow polydispersity. Using the PtBA-Br as macroinitiator, the PtBA-block-PS copolymer was prepared through ATRP. After terminated bromine atom was converted to end-functional azide group (P(tBA-b-St)-N 3 ), C 60 end-capped PtBA-PS block copolymers (P(tBA-b-St)-C 60 ) were synthesized by reacting C 60 with P(tBA-b-St)-N 3 . GPC characterizations showed that C 60 was chemically bonded to the end of P(tBA-b-St) chain and the products were mono-substituted. FT-IR, UV-Vis measurements confirmed that hydrolysis of P(tBA-b-St)-C 60 resulted in amphiphilic C 60 end-capped PAA-PS block copolymers. In additional, the photoconductivity of P(tBA-b-St)-C 60 was measured

  13. Preparation of mono-dispersed silver nanoparticles assisted by chitosan-g-poly(ε-caprolactone) micelles and their antimicrobial application

    International Nuclear Information System (INIS)

    Gu, Chunhua; Zhang, Huan; Lang, Meidong

    2014-01-01

    Graphical abstract: - Highlights: • Chemical modification of chitosan were conducted after phthaloyl protection of amino groups. • Silver nanoparticles were prepared in the presence of chitosan-based copolymer micelles. • The optimal time scale and weight ratios of silver to micelles were monitored by UV–vis spectrometer. - Abstract: Amphiphilic chitosan-graft-poly(ε-caprolactone) (CS-g-PCLs) copolymers were synthesized by a homogeneous coupling method and characterized by 1 H NMR, FTIR and ninhydrin assay. The graft copolymers were subsequently self-assembled into micelles, which were measured by DLS and TEM. The particle size of the micelles decreased as the segment grafting fraction was increased. Thereafter, silver nanoparticles were prepared in the presence of chitosan-based micelles under UV irradiation. The molar ratio and radiation time of silver to micelles were optimized with process monitored via UV–vis spectrophotometer. DLS and TEM were used to illustrate the particle structure and size while XRD patterns were applied to characterize the crystal structures of polymer-assisted silver nanoparticles. Films impregnated with silver nanoparticles were conducted with results of strong antimicrobial activities against Escherichia coli and Staphylococcus aureus as model Gram-negative and positive bacteria

  14. Enhancing the in vivo transdermal delivery of gold nanoparticles using poly(ethylene glycol and its oleylamine conjugate

    Directory of Open Access Journals (Sweden)

    Hsiao PF

    2016-05-01

    Full Text Available Pa Fan Hsiao,1–3 Sydney Peng,4 Ting-Cheng Tang,4 Shuian-Yin Lin,5 Hsieh-Chih Tsai4 1Department of Dermatology, Mackay Memorial Hospital, 2Mackay Medicine, Nursing and Management College, 3Mackay Medical College, New Taipei City, 4Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 5National Applied Research Laboratories, Instrument Technology Research Center, Hsinchu, Taiwan Abstract: In this study, we investigated the effect of (ethylene glycol (PEG and PEG–oleylamine (OAm functionalization on the skin permeation property of gold nanoparticles (GNS in vivo. Chemisorption of polymers onto GNS was verified by a red shift in the ultraviolet–visible spectrum as well as by a change in the nanoparticle surface charge. The physicochemical properties of pristine and functionalized nanoparticles were analyzed by ultraviolet–visible spectroscopy, zeta potential analyzer, and transmission electron microscopy. Transmission electron microscopy revealed that the interparticle distance between nanoparticles increased after GNS functionalization. Comparing the skin permeation profile of pristine and functionalized GNS, the follicular deposition of GNS increased twofold after PEG–OAm functionalization. Moreover, PEG- and PEG–OAm-functionalized nanoparticles were able to overcome the skin barrier and deposit in the deeper subcutaneous adipose tissue. These findings demonstrate the potential of PEG- and PEG–OAm-functionalized GNS in serving a multitude of applications in transdermal pharmaceuticals. Keywords: skin penetration, amphiphilic copolymer, gold nanoparticle, oleylamine, poly(ethylene glycol

  15. Au-coated 3-D nanoporous titania layer prepared using polystyrene-b-poly(2-vinylpyridine) block copolymer nanoparticles.

    Science.gov (United States)

    Shin, Won-Jeong; Basarir, Fevzihan; Yoon, Tae-Ho; Lee, Jae-Suk

    2009-04-09

    New nanoporous structures of Au-coated titania layers were prepared by using amphiphilic block copolymer nanoparticles as a template. A 3-D template composed of self-assembled quaternized polystyrene-b-poly(2-vinylpyridine) (Q-PS-b-P2VP) block copolymer nanoparticles below 100 nm was prepared. The core-shell-type nanoparticles were well ordered three-dimensionally using the vertical immersion method on the substrate. The polar solvents were added to the polymer solution to prevent particle merging at 40 degrees C when considering the interaction between polymer nanoparticles and solvents. Furthermore, Au-coated PS-b-P2VP nanoparticles were prepared using thiol-capped Au nanoparticles (3 nm). The 3-D arrays with Au-coated PS-b-P2VP nanoparticles as a template contributed to the preparation of the nanoporous Au-coated titania layer. Therefore, the nanoporous Au-coated titania layer was fabricated by removing PS-b-P2VP block copolymer nanoparticles by oxygen plasma etching.

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

    Science.gov (United States)

    García-Díaz, María; Foged, Camilla; Nielsen, Hanne Mørck

    2015-03-30

    Polymeric nanoparticles are widely investigated as drug delivery systems for oral administration. However, the hydrophobic nature of many polymers hampers effective loading of the particles with hydrophilic macromolecules such as insulin. Thus, the aim of this work was to improve the loading 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. The nanoparticles were characterized in terms of size, zeta potential, insulin encapsulation efficiency and loading capacity. Upon pre-assembly with lipids, there was an increased distribution of insulin into the organic phase of the emulsion, eventually resulting in significantly enhanced encapsulation efficiencies (90% as compared to 24% in the absence of lipids). Importantly, the insulin loading capacity was increased up to 20% by using the lipid-insulin complexes. The results further showed that a main fraction of the lipid was incorporated into the nanoparticles and remained associated to the polymer during release studies in buffers, whereas insulin was released in a non-complexed form as a burst of approximately 80% of the loaded insulin. In conclusion, the protein load in PLGA nanoparticles can be significantly increased by employing self-assembled protein-lipid complexes. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Crystal morphology modification by the addition of tailor-made stereocontrolled poly(N-isopropyl acrylamide).

    Science.gov (United States)

    Munk, Tommy; Baldursdottir, Stefania; Hietala, Sami; Rades, Thomas; Kapp, Sebastian; Nuopponen, Markus; Kalliomäki, Katriina; Tenhu, Heikki; Rantanen, Jukka

    2012-07-02

    The use of additives in crystallization of pharmaceuticals is known to influence the particulate properties critically affecting downstream processing and the final product performance. Desired functionality can be build into these materials, e.g. via optimized synthesis of a polymeric additive. One such additive is the thermosensitive polymer poly(N-isopropyl acrylamide) (PNIPAM). The use of PNIPAM as a crystallization additive provides a possibility to affect viscosity at separation temperatures and nucleation and growth rates at higher temperatures. In this study, novel PNIPAM derivatives consisting of both isotactic-rich and atactic blocks were used as additives in evaporative crystallization of a model compound, nitrofurantoin (NF). Special attention was paid to possible interactions between NF and PNIPAM and the aggregation state of PNIPAM as a function of temperature and solvent composition. Optical light microscopy and Raman and FTIR spectroscopy were used to investigate the structure of the NF crystals and possible interaction with PNIPAM. A drastic change in the growth mechanism of nitrofurantoin crystals as monohydrate form II (NFMH-II) was observed in the presence of PNIPAM; the morphology of crystals changed from needle to dendritic shape. Additionally, the amphiphilic nature of PNIPAM increased the solubility of nitrofurantoin in water. PNIPAMs with varying molecular weights and stereoregularities resulted in similar changes in the crystal habit of the drug regardless of whether the polymer was aggregated or not. However, with increased additive concentration slower nucleation and growth rates of the crystals were observed. Heating of the crystallization medium resulted in phase separation of the PNIPAM. The phase separation had an influence on the achieved crystal morphology resulting in fewer, visually larger and more irregular dendritic crystals. No proof of hydrogen bond formation between PNIPAM and NF was observed, and the suggested mechanism for

  18. Bacteriomimetic poly-γ-glutamic acid surface coating for hemocompatibility and safety of nanomaterials.

    Science.gov (United States)

    Shim, Gayong; Kim, Dongyoon; Kim, Jinyoung; Suh, Min Sung; Kim, Youn Kyu; Oh, Yu-Kyoung

    2017-08-01

    Poly-γ-glutamic acid (PGA), a major component of the bacterial capsule, is known to confer hydrophilicity to bacterial surfaces and protect bacteria from interactions with blood cells. We tested whether applying a bacteriomimetic surface coating of PGA modulates interactions of nanomaterials with blood cells or affects their safety and photothermal antitumor efficacy. Amphiphilic PGA (APGA), prepared by grafting phenylalanine residues to PGA, was used to anchor PGA to reduced graphene oxide (rGO) nanosheets, a model of hydrophobic nanomaterials. Surface coating of rGO with bacterial capsule-like APGA yielded APGA-tethered rGO nanosheets (ArGO). ArGO nanosheets remained stable in serum over 4 weeks, whereas rGO in plain form precipitated in serum within 5 minutes. Moreover, ArGO did not interact with blood cells, whereas rGO in plain form or as a physical mixture with PGA formed aggregates with blood cells. Mice administered ArGO at a dose of 50 mg/kg showed 100% survival and no hepatic or renal toxicity. No mice survived exposure at the same dose of rGO or a PGA/rGO mixture. Following intravenous administration, ArGO showed a greater distribution to tumors and prolonged tumor retention compared with other nanosheet formulations. Irradiation with near-infrared light completely ablated tumors in mice treated with ArGO. Our results indicate that a bacteriomimetic surface modification of nanomaterials with bacterial capsule-like APGA improves the stability in blood, biocompatibility, tumor distribution, and photothermal antitumor efficacy of rGO. Although APGA was used here to coat the surfaces of rGO, it could be applicable to coat surfaces of other hydrophobic nanomaterials.

  19. Paclitaxel-loaded poly(glycolide-co-ε-caprolactone-b-D-α-tocopheryl polyethylene glycol 2000 succinate nanoparticles for lung cancer therapy

    Directory of Open Access Journals (Sweden)

    Zhao TJ

    2013-05-01

    Full Text Available Tiejun Zhao,1 Hezhong Chen,1 Yuchao Dong,2 Jiajun Zhang,1 Haidong Huang,2 Ji Zhu,1 Wei Zhang21Institute of Cardiothoracic Surgery, 2Respiratory Department, Changhai Hospital, Shanghai, People's Republic of ChinaAbstract: In order to improve the therapeutic efficacy and minimize the side effects of lung cancer chemotherapy, the formulation of paclitaxel-loaded poly(glycolide-co-ε-caprolactone-b-D-α-tocopheryl polyethylene glycol 2000 succinate nanoparticles (PTX-loaded [PGA-co-PCL]-b-TPGS2k NPs was prepared. The novel amphiphilic copolymer (PGA-co-PCL-b-TPGS2k was synthesized by ring-opening polymerization and characterized by proton nuclear magnetic resonance spectroscopy and gel permeation chromatography. The PTX-loaded (PGA-co-PCL-b -TPGS2k NPs were characterized in terms of size, size distribution, zeta potential, drug encapsulation, surface morphology, and drug release. In vitro cellular uptakes of NPs were investigated with confocal laser scanning microscopy, indicating the coumarin 6-loaded (PGA-co-PCL-b -TPGS2k NPs could be internalized by human lung cancer A-549 cells. The antitumor effect of PTX-loaded NPs was evaluated, both in vitro and in vivo, on an A-549 cell tumor-bearing mouse model via intratumoral injection. The commercial PTX formulation Taxol was chosen as the reference. Experimental results showed that the PTX-loaded NPs possessed higher cytotoxicity and could effectively inhibit the growth of tumor. All the results suggested that amphiphilic copolymer (PGA-co-PCL-b -TPGS2k could act as a potential biological material for nanoformulation in the treatment of lung cancer.Keywords: (PGA-co-PCL-b TPGS2k, paclitaxel, nanoparticles, drug delivery, lung cancer

  20. Differentiation of human stem cells is promoted by amphiphilic pluronic block copolymers

    Directory of Open Access Journals (Sweden)

    Doğan A

    2012-09-01

    Full Text Available Aysegül Doğan,1 Mehmet E Yalvaç,1,2 Fikrettin Şahin,1 Alexander V Kabanov,3–5 András Palotás,6 Albert A Rizvanov71Department of Genetics and BioEngineering, College of Engineering and Architecture, Yeditepe University, Istanbul, Turkey; 2Center for Gene Therapy, Nationwide Children's Hospital, Ohio State University, Columbus, OH, USA; 3Center for Drug Delivery and Nanomedicine, 4Department of Pharmaceutical Sciences, College of Pharmacy, Durham Research Center, University of Nebraska Medical Center, Omaha, NE, USA; 5Laboratory of Chemical Design of Bio-nano-materials, Department of Chemistry, Mikhail V Lomonosov Moscow State University, Moscow, Russia; 6Asklepios-Med, Szeged, Hungary; 7Institute of Fundamental Medicine and Biology, Kazan (Volga Region Federal University, Kazan, RussiaAbstract: Stem cell usage provides novel avenues of tissue regeneration and therapeutics across disciplines. Apart from ethical considerations, the selection and amplification of donor stem cells remain a challenge. Various biopolymers with a wide range of properties have been used extensively to deliver biomolecules such as drugs, growth factors and nucleic acids, as well as to provide biomimetic surface for cellular adhesion. Using human tooth germ stem cells with high proliferation and transformation capacity, we have investigated a range of biopolymers to assess their potential for tissue engineering. Tolerability, toxicity, and their ability to direct differentiation were evaluated. The majority of pluronics, consisting of both hydrophilic and hydrophobic poly(ethylene oxide chains, either exerted cytotoxicity or had no significant effect on human tooth germ stem cells; whereas F68 increased the multi-potency of stem cells, and efficiently transformed them into osteogenic, chondrogenic, and adipogenic tissues. The data suggest that differentiation and maturation of stem cells can be promoted by selecting the appropriate mechanical and chemical