共查询到20条相似文献,搜索用时 15 毫秒
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Hai‐tao Zhang Prof. Dr. Xiao‐dong Fan Prof. Dr. Wei Tian Rong‐tian Suo Zhen Yang Yang Bai Wan‐bin Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):5000-5008
The controlled secondary self‐assembly of amphiphilic molecules in solution is theoretically and practically significant in amphiphilic molecular applications. An amphiphilic β‐cyclodextrin (β‐CD) dimer, namely LA‐(CD)2, has been synthesized, wherein one lithocholic acid (LA) unit is hydrophobic and two β‐CD units are hydrophilic. In an aqueous solution at room temperature, LA‐(CD)2 self‐assembles into spherical micelles without ultrasonication. The primary micelles dissociates and then secondarily form self‐assemblies with branched structures under ultrasonication. The branched aggregates revert to primary micelles at high temperature. The ultrasound‐driven secondary self‐assembly is confirmed by transmission electron microscopy, dynamic light scattering, 1H NMR spectroscopy, and Cu2+‐responsive experiments. Furthermore, 2D NOESY NMR and UV/Vis spectroscopy results indicate that the formation of the primary micelles is driven by hydrophilic–hydrophobic interactions, whereas host–guest interactions promote the formation of the secondary assemblies. Additionally, ultrasonication is shown to be able to effectively destroy the primary hydrophilic–hydrophobic balances while enhancing the host–guest interaction between the LA and β‐CD moieties at room temperature. 相似文献
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Min‐Min Fan Xi Zhang Jie Qin Bang‐Jing Li Xun Sun Sheng Zhang 《Macromolecular rapid communications》2011,32(19):1533-1538
This paper studies a kind of hollow nanospheres prepared by self‐assembly β‐cyclodextrins (β‐CDs) and poly(ethylene oxide)‐poly(propylene oxide)‐poly(ethylene oxide) (pluronic F127) for gene delivery. It was found that this kind of hollow nanospheres enable load PEI10K/DNA and the resulting F127 NH2 βCD/(PEI10K/DNA) with 0.08 µg/well DNA display equal or higher gene delivery capability compared to PEI10K/DNA with 1 µg/well DNA in the absence or presence of serum. The cytotoxicity of the nanospheres was over 100 times lower than that of PEI10K.
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Summary: Amphiphilic graft polyphosphazenes (EtTrp/PNIPAm‐PPP) with different mole ratios of hydrophobic groups to hydrophilic segments were synthesized by ring‐opening polymerization and subsequent substitution reactions. The self‐assembly behavior of these graft copolymers was studied in detail by TEM, SEM, CLSM, and AFM. Depending on the copolymer composition and common organic solvent employed in dialysis process, supramolecular aggregates ranging from network, nanospheres, high‐genus particles to macrophage‐like aggregates were produced with graft copolymers.
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Back Cover: Ultrasound‐Driven Secondary Self‐Assembly of Amphiphilic β‐Cyclodextrin Dimers (Chem. Eur. J. 13/2015) 下载免费PDF全文
Hai‐tao Zhang Prof. Dr. Xiao‐dong Fan Prof. Dr. Wei Tian Rong‐tian Suo Zhen Yang Yang Bai Wan‐bin Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):5256-5256
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Jin Wang Shuo Li Lin Ye Ai‐Ying Zhang Zeng‐Guo Feng 《Macromolecular rapid communications》2012,33(13):1143-1148
A polypseudorotaxane (PPR) comprising γ‐cyclodextrin (γ‐CD) as host molecules and poly(N‐isopropylacrylamide) (PNIPAM) as a guest polymer is prepared via self‐assembly in aqueous solution. Due to the bulky pendant isopropylamide group, PNIPAM exhibits size‐selectivity toward self‐assembly with α‐, β‐, and γ‐CDs. It can fit into the cavity of γ‐CD to give rise to a PPR, but cannot pass through α‐CD and β‐CD under the same conditions. The ratio of the number of γ‐CD molecules to entrapped NIPAM repeat units is kept at 1:2.2 or 1:2.4, determined by 1H NMR spectroscopy and TGA analysis, respectively, indicating that there are more than 2 but less than 3 NIPAM repeat units included by one γ‐CD molecule. This finding opens new avenues to PPR‐based supramolecular polymers to be used as solid, stimuli‐responsive materials. 相似文献
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Dongmei Tang Jiaping Lin Shaoliang Lin Suning Zhang Tao Chen Xiaohui Tian 《Macromolecular rapid communications》2004,25(13):1241-1246
Summary: Self‐association behaviors of poly(γ‐benzyl L ‐glutamate)‐graft‐poly(ethylene glycol) (PBLG‐graft‐PEG) and its mixtures with PBLG homopolymer in aqueous media were investigated by fluorescence spectroscopy, transmission electron microscopy (TEM), and nuclear magnetic resonance (NMR) spectroscopy. It was revealed that PBLG‐graft‐PEG could self‐assemble to form polymeric micelles with a core‐shell structure in the shape of spindle. The introduction of PBLG homopolymer not only decreases the critical micelle concentration, but also changes the morphology of the micelles.
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We report a novel, green hydrothermal‐synthesis route to well‐dispersed anatase TiO2 nanoparticles with particle sizes of 9–16 nm in the presence of β‐CD (β‐cyclodextrin). During the synthesis process, the CD‐containing synthesis mixture assembled in both longitudinal and latitudinal directions. Driven by the interaction between molecules, the β‐CDs assembled in the longitudinal direction to form long‐chain compounds, whereas in the latitudinal direction, they tended to form regular aggregates through coordination with the Ti species from the hydrolysis of tetrabutyl titanate. In view of the effect of the coordination and the steric hindrance of β‐CDs as a supramolecular shell, homogeneous nuclei and slow growth of TiO2 crystals during the synthesis process was observed, which was responsible for the formation of uniform TiO2 nanoparticles. The low β‐CD dosage and the high product yield (>90 %) demonstrated well the potential of this synthesis route in the large‐scale industrial production of anatase nanoparticles. 相似文献
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Unusual Cyclodextrin Derivatives as a New Avenue to Modulate Self‐ and Metal‐Induced Aβ Aggregation 下载免费PDF全文
Dr. Valentina Oliveri Dr. Francesco Bellia Dr. Adriana Pietropaolo Prof. Graziella Vecchio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):14047-14059
Mounting evidence suggests an important role of cyclodextrins in providing protection in neurodegenerative disorders. Metal dyshomeostasis is reported to be a pathogenic factor in neurodegeneration because it could be responsible for damage involving oxidative stress and protein aggregation. As such, metal ions represent an effective target. To improve the metal‐binding ability of cyclodextrin, we synthesized three new 8‐hydroxyquinoline‐cyclodextrin conjugates with difunctionalized cyclodextrins. In particular, the 3‐difunctionalized regioisomer represents the first example of cyclodextrin with two pendants at the secondary rim, resulting in a promising compound. The derivatives have significant antioxidant capacity and the powerful activity in inhibiting self‐induced amyloid‐β aggregation seems to be led by synergistic effects of both cyclodextrin and hydroxyquinoline. Moreover, the derivatives are also able to complex metal ions and to inhibit metal‐induced protein aggregation. Therefore, these compounds could have potential as therapeutic agents in diseases related to protein aggregation and metal dyshomeostasis. 相似文献
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Chloe A. Cho Chao Liang Janesha Perera Margaret A. Brimble Simon Swift Jianyong Jin 《Macromolecular bioscience》2020,20(7)
Nine guanidinylated amphiphilic polycarbonates are rationally designed and synthesized. Each polymer has the same biodegradable backbone but different side groups. The influence of the hydrophobic/hydrophilic effect on antimicrobial activities and cytotoxicity is systematically investigated. The results verify that tuning the length of the spacer arm between the cationic guanidine group and the polycarbonate backbone is an efficient design strategy to alter the hydrophobic/hydrophilic balance without changing the cationic charge density. A spacer arm of six methylene units (CH2)6 shows the best antimicrobial activity (minimum inhibitory concentration, MIC = 40 µg mL?1 against Escherichia coli, MIC = 20 µg mL?1 against Staphylococcus aureus, MIC = 40 µg mL?1 against Candida albicans) with low hemolytic activity (HC50 > 2560 µg mL?1). Furthermore, the guanidinylated polycarbonates exhibit the ability to self‐assemble and present micelle‐like nanostructure due to their intrinsic amphiphilic macromolecular structure. Transmission electron microscopy and dynamic light scattering measurements confirm polymer micelle formation in aqueous solution with sizes ranging from 82 to 288 nm. 相似文献
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Cécile Machut‐Binkowski Dr. François‐Xavier Legrand Nathalie Azaroual Prof. Dr. Sébastien Tilloy Prof. Dr. Eric Monflier Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(33):10195-10201
A new diphenylphosphane based on a β‐cyclodextrin skeleton that exhibits a dual solubility in water and in organic solvent was synthesised. Interestingly, a solvent‐dependent conformation change was evidenced by NMR spectroscopy studies; the self‐inclusion of a phenyl group of the phosphane moiety into cyclodextrin cavity observed in water disappeared in organic solvents due to a change in conformation. Hydrogenation or hydroformylation reactions performed in water and in organic solvents showed that this ligand was able to stabilise catalytically active rhodium species in solution. In the case of the hydroformylation reaction, it was demonstrated that regioselectivity was influenced by the solvent‐dependent conformation of the ligand. 相似文献
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Summary: A water‐soluble gold nanoparticle aggregate 2 was prepared by chloroauric acid and a polypseudorotaxane 1 of mono‐6‐thio‐β‐cyclodextrin with poly(propylene glycol) bis(2‐aminopropyl ether) ( ≈ 2 000) in the presence of sodium borohydride in N,N‐dimethylformamide (DMF) solution. The investigative results indicated that the gold nanoparticle aggregate 2 might act as an efficient DNA‐cleavage reagent.
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Luigi Carbone Dr. Liberato Manna Dr. Carsten Sönnichsen Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(24):4282-4283
Amphiphilic hybrid materials are formed from polymer‐coated semiconductor nanoparticles that simulate a surfactant‐like response (see picture). The strength and density of the surface coating are the key assembling forces driving a transition from single particles to cylindrical or vesicular superstructures.
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Eunji Lee Jung‐Keun Kim Myongsoo Lee Prof. 《Angewandte Chemie (International ed. in English)》2009,48(20):3657-3660
Deep‐water scrolls: It is demonstrated that amphiphilic rods containing lateral flexible chains self‐assemble into two‐dimensional sheets in aqueous solution (see picture). Remarkably, the sheets roll up reversibly into tubular scrolls upon heating, as confirmed by cryo‐transmission electron microscopy and fluorescence microscopy.
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Dr. Jessica Gwyther Prof. Joe B. Gilroy Prof. Paul A. Rupar David J. Lunn Emily Kynaston Prof. Sanjib K. Patra Dr. George R. Whittell Prof. Mitchell A. Winnik Prof. Ian Manners 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(28):9186-9197
With the aim of accessing colloidally stable, fiberlike, π‐conjugated nanostructures of controlled length, we have studied the solution self‐assembly of two asymmetric crystalline–coil, regioregular poly(3‐hexylthiophene)‐b‐poly(2‐vinylpyridine) (P3HT‐b‐P2VP) diblock copolymers, P3HT23‐b‐P2VP115 (block ratio=1:5) and P3HT44‐b‐P2VP115 (block ratio=ca. 1:3). The self‐assembly studies were performed under a variety of solvent conditions that were selective for the P2VP block. The block copolymers were prepared by using Cu‐catalyzed azide–alkyne cycloaddition reactions of azide‐terminated P2VP and alkyne end‐functionalized P3HT homopolymers. When the block copolymers were self‐assembled in a solution of a 50 % (v/v) mixture of THF (a good solvent for both blocks) and an alcohol (a selective solvent for the P2VP block) by means of the slow evaporation of the common solvent; fiberlike micelles with a P3HT core and a P2VP corona were observed by transmission electron microscopy (TEM). The average lengths of the micelles were found to increase as the length of the hydrocarbon chain increased in the P2VP‐selective alcoholic solvent (MeOH<iPrOH<nBuOH). Very long (>3 μm) fiberlike micelles were prepared by the dialysis of solutions of the block copolymers in THF against iPrOH. Furthermore the widths of the fibers were dependent on the degree of polymerization of the chain‐extended P3HT blocks. The crystallinity and π‐conjugated nature of the P3HT core in the fiberlike micelles was confirmed by a combination of UV/Vis spectroscopy, photoluminescence (PL) measurements, and wide‐angle X‐ray scattering (WAXS). Intense sonication (iPrOH, 1 h, 0 °C) of the fiberlike micelles formed by P3HT23‐b‐P2VP115 resulted in small (ca. 25 nm long) stublike fragments that were subsequently used as initiators in seeded growth experiments. Addition of P3HT23‐b‐P2VP115 unimers to the seeds allowed the preparation of fiberlike micelles with narrow length distributions (Lw/Ln <1.11) and lengths from about 100‐300 nm, that were dependent on the unimer‐to‐seed micelle ratio. 相似文献
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Dr. Dimitrios Priftis Dr. Lorraine Leon Ziyuan Song Dr. Sarah L. Perry Khatcher O. Margossian Anna Tropnikova Prof. Jianjun Cheng Prof. Matthew Tirrell 《Angewandte Chemie (International ed. in English)》2015,54(38):11128-11132
Reported is the ability of α‐helical polypeptides to self‐assemble with oppositely‐charged polypeptides to form liquid complexes while maintaining their α‐helical secondary structure. Coupling the α‐helical polypeptide to a neutral, hydrophilic polymer and subsequent complexation enables the formation of nanoscale coacervate‐core micelles. While previous reports on polypeptide complexation demonstrated a critical dependence of the nature of the complex (liquid versus solid) on chirality, the α‐helical structure of the positively charged polypeptide prevents the formation of β‐sheets, which would otherwise drive the assembly into a solid state, thereby, enabling coacervate formation between two chiral components. The higher charge density of the assembly, a result of the folding of the α‐helical polypeptide, provides enhanced resistance to salts known to inhibit polypeptide complexation. The unique combination of properties of these materials can enhance the known potential of fluid polypeptide complexes for delivery of biologically relevant molecules. 相似文献