Synthesis and characterization of a novel two-component organogelator based on ion-bonded discotic complex

A novel ion-bonded discotic complex was prepared from 2,3,6,7,10,11-hexakis(N,N-dimethylaminopropylaminocarbonylmethoxy)triphenylene (HDTP) and 4'-dodecyloxybiphenyl-4-carboxylic acid (DBC) by ionic self-assembly (ISA) route and characterized by Fourier transform infrared (FTIR) spectrum. We found that the complex can self-assemble into stable gels in aromatic hydrocarbons. Nanofibers with diameters of 50-130 nm were observed in the gels by transmission electron micrograph (TEM).

Controllable synthesis of metal hydroxide and oxide nanostructures by ionic liquids assisted electrochemical corrosion method

Cu(OH)(2) nanowires have been synthesized by anodic oxidation of copper through a simple electrolysis process employing ionic liquid as an electrolyte. Controlling the electrochemical conditions can qualitatively modulate the lengths, amounts, and shapes of Cu(OH)(2) nanostructures. A rational mechanism based on coordination self-assembly and oriented attachment is proposed for the selective formation of the polycrystalline Cu(OH)(2) nanowires. In addition, the FeOOH nanoribbons, Ni(OH)(2) nanosheets, and ZnO nanospheres were also synthesized by this route, indicative of the universality of the electrochemical route presented herein. The morphologies and structures of the synthesized nanostructures have been characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), powder X-ray diffraction (XRD). Fourier transform infrared spectra (FT-IR), and thermogravimetric (TG). (C) 2007 Elsevier Masson SAS. All rights reserved

Multilayer structured carbon nanotubes/poly-L-lysine/laccase composite cathode for glucose/O-2 biofuel cell

Multilayer film of laccase, poly-L-lysine (PLL) and multi-walled carbon nanotubes (MWNTs) were prepared by a layer-by-layer self-assembly technique. The results of the UV-vis spectroscopy and scanning electron microscopy studies demonstrated a uniform growth of the multilayer. The catalytic behavior of the modified electrode was investigated. The (MWNTs/PLL/laccase)(n) multilayer modified electrode catalyzed four-electron reduction of O-2 to water, without any mediator.

Hybridization of poly(4-vinyl pyridine)-b-polystyrene-b-poly(4-vinyl pyridine) aggregates in dioxane/water solution

Self-assembly of binary blends of two triblock copolymers of poly(4-vinyl pyridine)-b-polystyrene-b-poly(4-vinyl pyridine), i.e., P4VP(43)-b-PS260-b-P4VP(43) (P1) and P4VP(43)-b-PS366-b-P4VP(43) (P2), in dioxane/water solution was studied. These two triblock copolymers individually tend to form vesicles (P2) and cylindrical micelles (P1) in dilute solution. It was found that copolymer components in the blend, sample preparation method, and annealing time had significant effect on hybridization aggregate morphology. By increasing P1 content in the copolymer blends, fraction of looped and stretched cylinders increased, while fraction of bilayers decreased. Nearly no bilayer was observed when P1 content was above 85 wt%.

Hollow DNA/PLL microcapsules with tunable degradation property as efficient dual drug delivery vehicles by alpha-chymotrypsin degradation

Hollow deoxyribonucleic acid (DNA)/poly-L-lysine (PLL) capsules were successfully fabricated through a layer-by-layer (LbL) self-assembly of DNA and PLL on porous CaCO3 microparticles, followed by removal of templates with ethylenediamine tetraacetic acid disodium salt (EDTA). The enzymatic degradation of the capsules in the presence of alpha-chymotrypsin was explored. The higher the enzyme concentration, the higher is the degradation rate of hollow capsules. in addition, glutaric dialdehyde (GA) cross-linking was found to be another way to manipulate degradation rate of hollow capsules.

Monodisperse Co-oligomer Approach toward Nanostructured Films with Alternating Donor-Acceptor Lamellae

A series of donor-acceptor (D-A) co-oligomers with oligo(fluorene-alt-bithiophene) and perylene diimide as donor and acceptor segments, respectively, have been designed and synthesized. They can self-assembly into alternating D-A lamellar nanostructured films with the periods depending on the molecular length. These films have been successfully used in fabrication of high-performance single-molecular solar cells with power conversion efficiency up to 1.50%.

Bump-Surface Multicompartment Micelles from a Linear ABC Triblock Copolymer: A Combination Study by Experiment and Computer Simulation

Novel bump-surface multicompartment micelles formed by a linear amphiphilic ABC triblock copolymer via self-assembly in selective solvent were successfully observed both in simulation and experiment. The results revealed that the block A forms the most inner core, and the blocks B and C form the inner and outer layers, respectively, and the bumps were formed by block A and more likely to be born on curving surfaces. Moreover, the micelle shape could be controlled by changing the solvent selectivity of the blocks A and B. Spherical, cylindrical, and discoidal micelles with bumpy surfaces were obtained both in experiment and simulation.

Luminescent and Mesoporous Europium-Doped Bioactive Glasses (MBG) as a Drug Carrier

Luminescent and mesoporous europium-doped bioactive glasses (MBG:Eu) were successfully synthesized by a two-step acid-catalyzed self-assembly process combined with hydrothermal treatment in an inorganic-organic system. The obtained MBG was performed as a drug delivery carrier to investigate the drug storage/release properties using ibuprofen (IBU) as a model drug. The structural, morphological, textural and optical properties were well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N-2 adsorption/desorption, and photoluminescence (PL) spectra, respectively. The results reveal that the MBG exhibit the typical ordered characteristics of the hexagonal mesostructure. This composite shows sustained release profile with ibuprofen as the model drug. The IBU-loaded samples still show red luminescence of Eu3+ (D-5(0)-F-7(1, 2)) under UV irradiation, and the emission intensities of Eu3+ in the drug carrier system vary with the released amount of IBU, thus making the drug release be easily tracked and monitored by the change of the luminescence intensity.

Vesicles Formed by Oligostyrene-block-Oligoaniline-block-Oligostyrene Triblock Oligomer

Novel pi-conjugated coil-rod-coil triblock oligomers containing optoelectronic active oligoaniline segments were synthesized. The block oligomer can self-assemble into diverse aggregating morphologies including spherical micelles and thin-layer vesicles in THF, which is found associated with the removing of the protecting groups of oligoaniline segments. A possible mechanism was proposed to explain the self-assembly behavior changes in which chain conformation variation of the aniline segments initiated from deprotection of the nitrogen atoms is pointed to be the key factor that dominates the transition process.

Conducting polyaniline film from aqueous dispersion: Crystallizable side chain forced lamellar structure for high conductivity

Aqueous conducting polyaniline dispersion was prepared employing acidic phosphate ester bearing hydrophilic ethylene glycol segment as dopant, and conducting film with electrical conductivity of 25 S/cm was obtained from the dispersion. Ordered self-assembly lamellar structure with interlamellar distance of 1.2 nm was observed in the film, which consisted of alternating layers of rigid polyaniline chain and flexible phosphate ester side chains, where the phosphate side chain layer was separated by two rigid polyaniline layers. The lamellar structure leading to high conducting film was formed due to the confinement of polyaniline chain by crystallizable phosphate side chain, since the electrical conductivity decreased by four orders of magnitude once the dopant side chain crystalline was destroyed. The crystallizable side chain forced lamellar structure is expected to be a new chance for highly conducting polyaniline.

Controlled synthesis of nanoporous Au microsheet via surfactant emulsion template

A facile and wet-chemical approach was employed to control synthesis of self-organizing, hyperbranched nanoporous Au microsheet with high quality in bulk quantity. This method produced nanoporous Au microsheets with a thickness of 7-15 nm. The microsheets were composed of irregularly interconnected planar Au nanoplates with interstices, i.e. nanopores of 10-50 nm. And the nanoporous Au microsheets were enveloped in 10-30 nm thick polyaniline (PANI) sheaths. The morphology of the nanostructured Au composites could also be easily tuned by changing the concentration of aniline and chlorauric acid. The dendritic and epitaxial growth of nanoporous Au microsheet was believed as the diffusion-limited process confined in the lamellar emulsion phase through self-assembly of aniline and dodecylsulfate. The solution reaction proceeded at a mild condition (room temperature and aqueous solutions), and less toxic reagents were employed instead of extreme toxic and corrosive chemicals.

Nanoelectrode ensembles based on semi-interpenetrating network of carbon nanotubes

A method for preparing nanoelectrode ensembles based on semi-interpenetrating network (SIN) of multi-walled carbon nanotubes (MWNTs) on gold electrode through phase-separation method is initially proposed. Individual nanoelectrode owns irregular three-dimensional MWNTs networks, which is denoted as SIN-MWNTs. On the as-prepared SIN-MWNTs nanoelectrode ensembles, the assembled MWNTs clusters in nanoscale serve as individual nanoelectrode and the electroinactive lipid networks located on the top of alkanethiol monolayer are used as a shielding layer. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), tapping-mode atomic force microscopy (TM-AFM) and scanning electron microscopy (SEM) were used to characterize the as-prepared SIN-MWNT nanoelectrode ensembles. Experimental results indicate that the well-defined nanoelectrode ensembles were prepared through self-assembly technology. Meantime, sigmoid curves in a wide scanning range can be obtained in CV experiments. This study may pave the way for the construction of truly nanoscopic nanoelectrode arrays by bottom-up strategy.

Enantiomeric PLA-PEG block copolymers and their stereocomplex micelles used as rifampin delivery

A novelty approach to self-assembling stereocomplex micelles by enantiomeric PLA-PEG block copolymers as a drug delivery carrier was described. The particles were encapsulated by enantiomeric PLA-PEG stereocomplex to form nanoscale micelles different from the microspheres or the single micelles by PLLA or PDLA in the reported literatures. First, the block copolymers of enantiomeric poly(L-lactide)-poly(ethylene-glycol) (PLLA-PEG) and poly(D-lactide)-poly(ethylene-glycol) (PDLA-PEG) were synthesized by the ring-opening polymerization of L-lactide and D-lactide in the presence of monomethoxy PEG, respectively. Second, the stereocomplex block copolymer micelles were obtained by the self-assembly of the equimolar mixtures of enantiomeric PLA-PEG copolymers in water. These micelles possessed partially the crystallized hydrophobic cores with the critical micelle concentrations (cmc) in the range of 0.8-4.8 mg/l and the mean hydrodynamic diameters ranging from 40 to 120 nm. The micelle sizes and cmc values obviously depended on the hydrophobic block PLA content in the copolymer.Compared with the single PLLA-PEG or PDLA PEG micelles, the cmc values of the stereocomplex micelles became lower and the sizes of the stereocomplex micelles formed smaller. And lastly, the stereocomplex micelles encapsulated with rifampin were tested for the controlled release application.

Luminescent supramolecular polymers: Cd2+-directed polymerization and properties

A family of supramolecular polymers was prepared via Cd2+-directed self-assembly polymerization of his (2,2':6',2 ''-terpyridine)-based ligand monomers, using oligofluorenes and triphenylamine as bridges under mild conditions. The polymers were fully characterized using thermogravimetric analysis, inherent viscosity, electrochemical measurements, UV-visible spectroscopy, photoluminescence (PL) and electroluminescence (EL). Polymers with oligofluorenes as spacers exhibited blue emission (434-442 nm) in dimethyl acetamide (DMAc) solution, while polymers with triphenylamine as spacer presented an emission peak at 494 nn in DMAc solution. Complexation polymerization of bis(2,2':6',2 ''-terpyridine)-based ligand monomers with cadmium(II) improved fluorescence quantum yields dramatically, and the film PL quantum yields of these polymers were about 0.38-0.54. Single-layer light-emitting diodes were fabricated with the configuration indium tin oxide (ITO)/polymer/Ca/Al; the EL showed green emission and the onset voltages of the devices were 8-11 V.