Search results for "MOLECULE"
showing 10 items of 5162 documents
Bicyclo[2.2.2]octane-1,4-dicarboxylic acid: towards transparent metal–organic frameworks
2017
The preparation of transparent porous materials can offer a different access towards the study of molecules under solid confined space. Metal-organic frameworks represent a unique opportunity due to their tunable pore size, however aromatic linkers present strong absorption and reduce the transparency. Herein, we report the first example of a MOF with bicyclic organic dicarboxylic linkers and its use as a solid solvent.
Silica-coated Au@ZnO Janus particles and their stability in epithelial cells
2020
Multicomponent particles have emerged in recent years as new compartmentalized colloids with two sides of different chemistry or polarity that have opened up a wide field of unique applications in medicine, biochemistry, optics, physics and chemistry. A drawback of particles containing a ZnO hemisphere is their low stability in biological environment due to the amphoteric properties of Zn2+. Therefore we have synthesized monodisperse Au@ZnO Janus particles by seed-mediated nucleation and growth whose ZnO domain was coated selectively with a thin SiO2 layer as a protection from the surrounding environment that imparts stability in aqueous media while the Au domain remained untouched. The thi…
Iron and iron-oxide magnetic nanoparticles as signal-amplification elements in electrochemical biosensing
2015
Abstract Growing demands for ultrasensitive biosensing have led to the development of numerous signal-amplification strategies. Based on their unique properties (i.e., electro-conductivity, bio-compatibility and ease of synthesis), various iron magnetic nanoparticles (MNPs) have proved to be an excellent nanomaterial for applications in electrochemical biosensing. This review shows how iron MNPs have made significant contributions in the development of electrochemical nanobiosensors, including immuno-, enzyme, DNA and aptamer types. More importantly, we discuss in detail different aspects of the electrochemical biosensors (e.g., modes of magnetic particles, detection techniques, analytes an…
Dendrimer-encapsulated and cored metal nanoparticles for electrochemical nanobiosensing
2014
Abstract We discuss nanosized dendrimers from the point of view of electrochemical-biosensor design. We review electrochemical biosensors based on dendrimer-encapsulated metal nanoparticles (NPs) and their various applications (e.g., measurement of small biological and toxic molecules, detection of DNA, and immunosensing of disease biomarkers). Finally, we discuss some future applications of electrochemical biosensors based on dendrimer-encapsulated metal NPs.
Synthesis, properties and processability of a new class of semirigid liquid crystalline copolyesteramides
1995
Abstract A new family of semirigid main chain liquid crystalline polymers (LCPs), referred to as SBAN, characterized by fairly good processability and mechanical properties, and improved thermal resistance, have been synthesized by the melt polycondensation of sebacic acid (S), 4,4′-dihyhxybiphenyl (B), 4-aminobenzoic acid (A), and 2-hydroxy-6-naphthoic acid (N), in a wide range of compositions. The molar concentration of the A ahd N units, in these LCPs must be kept lower than ca 40 and 60%, respectively, in order to avoid the formation of homopolymeric blocks, which impair spinnability. The presence of A units grants the formation of hydrogen bonds between neighboring macromolecules, and …
Photocleavable microcapsules built from photoreactive nanospheres.
2005
We show how photo-cross-linking of nanoparticles within the micrometer-sized thin oil shell of water-oil-water emulsion droplets leads to a new species of optically addressable microcontainers. The inner water droplet of these emulsions may contain drugs, dyes, or other water-soluble components, leading to filled containers. The thickness, mechanical stability, and light resistance of the container walls can be controlled in a simple way by the amount and adjustable photoreactivity of the nanoparticles. Importantly, the chemical bonds between the nanoparticles constituting the microcapsule shell can be cleaved photochemically by irradiation with UV light. This optically controlled destructi…
Enlarged pore size in nanoparticulated bimodal porous silicas: Improving accessibility
2016
Abstract Mass-transfer kinetics seems to be highly favored in siliceous materials constructed from the aggregation of mesoporous nanoparticles. Besides intra-particle mesopores, over the course of the aggregation process an inter-particle (textural) large pore system is generated. Diffusion constrains through the resulting hierarchically structured pore systems mainly depend on the characteristics of the intra-particle mesopores. By using alkanes as swelling agents, we have been able to significantly increase the intra-particle mesopore size in previously well characterized UVM-7 materials. The Winsor-III-like behavior associated with the presence of alkanes in the hydro-alcoholic reaction …
Tracer diffusion in polymer and organic liquids close to the glass transition studied by forced rayleigh scattering
2007
Translational diffusion coefficients D of photochronic dye molecules have been measured by forced Rayleigh scattering in polymer diluent systems at compositions from pure polymer to pure diluent. D could be measured down to below the glass transition temperature T g. In the pure diluent, D(T g) was found typically about two decades below that in the pure polymer but still far above the Stokes-Einstein prediction extrapolated from high temperatures. Some experimental results are in contrast with predictions from free-volume theory.
Coherent Electronic Coupling versus Localization in Individual Molecular Dimers
2004
International audience; The electronic excitation transfer and coherent electronic coupling strength were investigated in molecular dimers by spectrally resolved confocal fluorescence spectroscopy. The direct probe of electronic coupling strength distribution was possible due to static disorder in polymer host by single molecule measurements. The dimers with delocalized excitation were also found in comparison to emission originated from localized states. The delocalized and localized state transitions were observed for dimers which were attributed to structural fluctuations of guest-host system.
2H NMR studies of phase behaviour and molecular motions of doped discotic liquid-crystalline systems
1990
Abstract A discotic triphenylene monomer as well as a dimer and a main chain polymer, all substituted with heptyloxy side groups, were doped with an electron acceptor (2,4,7-trinitrofluorenone (TNF)) to give charge transfer complexes. These doped systems were aligned in a magnetic field, thus proving their liquid crystallinity. 2H NMR measurements show that the electron acceptor molecules are incorporated into the columns built of triphenylene cores. In the charge transfer complex with the triphenylene monomer almost all the electron acceptor molecules stack in the columns even close to the clearing temperature T 1, while for the dimer and especially for the polymer a significant fraction o…