Filtern
Erscheinungsjahr
Dokumenttyp
- Wissenschaftlicher Artikel (150)
- Postprint (15)
- Ausgabe (Heft) zu einer Zeitschrift (2)
- Monographie/Sammelband (1)
- Teil eines Buches (Kapitel) (1)
- Sonstiges (1)
- Rezension (1)
Gehört zur Bibliographie
- ja (171) (entfernen)
Schlagworte
- Janus emulsions (5)
- nanoparticles (5)
- Cryo-SEM (4)
- HRTEM (4)
- gold nanoparticles (4)
- nanotriangles (4)
- wavelength (4)
- Interfacial tension (3)
- Microemulsions (3)
- Molecular dynamics simulations (3)
- Pickering emulsions (3)
- Polyampholytes (3)
- SERS (3)
- Surfactant micelles (3)
- mu-DSC (3)
- size (3)
- tailspike protein (3)
- 4-nitrobenzenethiol (2)
- AOT bilayer (2)
- AU (2)
- Calcium phosphates (2)
- Direct electron transfer (2)
- Gold nanoparticles (2)
- HK620 (2)
- Human sulfite oxidase (2)
- Janus droplets (2)
- Kinetically controlled nanocrystal growth (2)
- Maltose-modified PEI (2)
- Maltose-modified poly(ethyleneimine) (2)
- Microemulsion (2)
- Molecular dynamics (2)
- Nanoparticles (2)
- Network structure (2)
- O-antigen specific phage (2)
- PEI coating (2)
- Polyethyleneimine (2)
- Raman spectroscopy (2)
- Ring tensiometry (2)
- SAXS (2)
- SERS enhancement factor (2)
- TEM (2)
- X-ray scattering (2)
- aminothiophenol (2)
- catalysis (2)
- charge-transfer (2)
- chitosan (2)
- click chemistry (2)
- cryogel (2)
- dimerization of 4-nitrothiophenol (2)
- drug delivery system (2)
- dye mixture (2)
- dye removal (2)
- enhanced raman-scattering (2)
- enzyme (2)
- gold nanotriangles (2)
- in vitro particle opening (2)
- lipopolysaccharide (2)
- magnetic manipulation (2)
- magnetite nanoparticles (2)
- metal (2)
- methyl orange (2)
- methylene blue (2)
- microemulsion (2)
- microgels (2)
- monolayer formation (2)
- nanoflowers (2)
- optical-properties (2)
- photocatalysis (2)
- podovirus (2)
- polyampholytes (2)
- polyelectrolyte (2)
- polymersomes (2)
- poly‐ ε ‐ caprolactone (2)
- sers (2)
- shape (2)
- spiked and crumble gold nanotriangles (2)
- step (2)
- ultrafast (2)
- undulated (2)
- water treatment (2)
- AOT (1)
- AOT/BDAC micelles (1)
- Adsorption (1)
- Alternating polyampholytes (1)
- Anisotropic gold nanoplatelets (1)
- Anti-HIV (1)
- Bentonite clay (1)
- Bioelectrocatalysis (1)
- Biomineralization (1)
- Block copolymers (1)
- Bone repair material (1)
- Cationic surfactants (1)
- CdS quantum dots (1)
- Cellular uptake (1)
- Chitosan (1)
- Composite hydrogels (1)
- DLS (1)
- DNA complexation (1)
- DNA ejection (1)
- DNA polyplexes (1)
- DNA release (1)
- DNA viruses (1)
- DNA-PEI polyplexes (1)
- Decontamination (1)
- Defects (1)
- Drop morphology (1)
- Drop profile analysis tensiometry (1)
- Dynamic light scattering (1)
- Emulsification (1)
- Emulsion destabilization (1)
- Emulsions (1)
- Enzyme catalysis (1)
- Extraction (1)
- Field flow fractionation (1)
- GOIP (1)
- Gelatin-NaCMC (1)
- Gelatin-NaPAA composites (1)
- Gelatin-chitosan composites (1)
- Gelatin-chitosan scaffolds (1)
- Gold (1)
- Gold cluster (1)
- Gold nanoparticle (1)
- Gold nanotriangles (1)
- Gold surface (1)
- Gold surfaces (1)
- Gold triangles (1)
- Heavy metal ions (1)
- Heparin (1)
- Hexagons and nanorods (1)
- Hydrogel (1)
- Hydrogel disks (1)
- Hydrogel microparticles (1)
- Hydrogel microspheres (1)
- Hydrogels (1)
- Hydroxyethyl starch (HES) (1)
- In vivo imaging system (IVIS) (1)
- In vivo-in vitro correlation (1)
- Interfacial equilibrium (1)
- Ionic liquid (1)
- Irradiation (1)
- Janus drops (1)
- Janus emulsion (1)
- Janus gels (1)
- Kinetic analysis (1)
- L-Cysteine (1)
- LSPR (1)
- Lamellar liquid crystals (1)
- Lasers (1)
- Liquids (1)
- MD simulations (1)
- Magnetic-responsive (1)
- Magnetite and gold nanoparticles (1)
- Magnetite-gold nanoparticles (1)
- Magnetization measurements (1)
- Mesh size (1)
- Microfluidics (1)
- Morphology (1)
- Nanocrystal growth (1)
- Nanotriangle stacking and welding (1)
- Nanotriangles (1)
- Neutron spin echo (1)
- Nuclear magnetic resonance spectroscopy (1)
- O-antigen specificity (1)
- Percolation (1)
- Phospholipids (1)
- Pickering Janus emulsions (1)
- Pluronics (1)
- Polymer capped gold nanoparticles (1)
- Polymer-coating (1)
- Polypeptoids (1)
- Polyplexes (1)
- Protein delivery (1)
- Protein structure (1)
- Protein voltammetry (1)
- Release (1)
- Release studies (1)
- Reverse microemulsions (1)
- Ring method (1)
- SANS (1)
- SDS (1)
- SDS inverse micelle (1)
- SEM (1)
- Salmonella enterica (1)
- Salmonella myovirus (1)
- Satellite hybrid (1)
- Scattering (1)
- Self-assembly (1)
- Silicon (1)
- Spinning drop (1)
- Sulfite biosensor (1)
- Superparamagnetic magnetite (1)
- Supramolecular ball structure (1)
- Surface removal (1)
- Template phase (1)
- Templated self-assembly (1)
- Thermoresponsive (1)
- Toxicity (1)
- Tube-like template phase (1)
- Tubular network structure (1)
- UV-Vis-NIR (1)
- Vesicle formation (1)
- Water (1)
- Winsor phases (1)
- acidity constants (1)
- adsorption (1)
- aqueous-solution (1)
- aspect-ratio (1)
- bacteriophage (1)
- bicontinuous phase (1)
- bilayer (1)
- bioelectrocatalysis (1)
- catanionic surfactant bilayer (1)
- catanionic vesicles (1)
- cationic surfactants (1)
- cellulose (1)
- chemical modification (1)
- chemical-synthesis (1)
- composites (1)
- confocal raman microscopy (1)
- conformational transitions (1)
- contractile tail (1)
- copolymers (1)
- crystal growth (1)
- crystallization (1)
- degradation (1)
- delivery (1)
- dimensional stability (1)
- dimerization (1)
- direct electrochemistry (1)
- droplet-droplet interactions (1)
- emulsion inversion (1)
- emulsion microscopy (1)
- epsilon-caprolactone (1)
- equilibrium topology (1)
- film tuning (1)
- fluorescence (1)
- gelatin/chitosan hydrogel scaffold (1)
- gemini surfactant (1)
- glycobiology (1)
- gold cluster (1)
- gold nanoflowers (1)
- gold nanostructures (1)
- gold surface (1)
- gold-polymer hybrid shell (1)
- halide-ions (1)
- heartwood formation (1)
- heat measurement (1)
- human sulfite oxidase (1)
- hyaluronic acid (1)
- immobilization (1)
- interfaces (1)
- ionic liquids (1)
- janus emulsions (1)
- l-cysteine (1)
- lipopolysaccharide (YLPS) (1)
- liquids (1)
- maltose-modified poly(ethyleneimine) (1)
- maltosylated poly(ethyleneimine) (1)
- mechanical-properties (1)
- metal nanoparticles (1)
- microemulsions (1)
- microfluidics (1)
- miscibility (1)
- mixtures (1)
- molecular machine (1)
- morphological transformation (1)
- multiple emulsion preparation (1)
- nanoindentation (1)
- nanoprisms (1)
- nanorods (1)
- nanostructures (1)
- ordering process (1)
- pH-responsive (1)
- photocurrent (1)
- poly(acrylamide) hydrogels (1)
- poly(ethyleneimine) (1)
- polylactide (1)
- polymer-modification (1)
- protonation (1)
- radical polymerization (1)
- ring-opening polymerization (1)
- self-assembly (1)
- semiempirical calculations (1)
- silver (1)
- silver nanowires (1)
- stannous octoate (1)
- stereocomplexation (1)
- structural biology (1)
- structural-characterization (1)
- surface-plasmon resonance (1)
- undulated nanoplatelets (1)
- vesicles (1)
- viscosity (1)
- wood cell wall (1)
We report a modified approach to the batch scale preparation of completely engulfed core-shell emulsions or partially engulfed Janus emulsions with colorful optical properties, containing water, olive oil, and silicone oil. The in situ reduction of gold chloride, forming gold nanoparticles (AuNPs) at the olive oil interface in the absence or presence of chitosan, leads to the formation of compartmentalized olive-silicone oil emulsion droplets in water. In the absence of additional reducing components, time-dependent morphological transformations from partial engulfment to complete engulfment were observed. Similar experiments in the presence of chitosan or presynthesized AuNPs show an opposite time-dependent trend of transformation of core-shell structures into partially engulfed ones. This behavior can be understood by a time-dependent rearrangement of the AuNPs at the interface and changes of the interfacial tension. The Pickering effect of AuNPs at oil-water and oil-oil interfaces brings not only color effects to individual microdroplets, which are of special relevance for the preparation of new optical elements, but also a surprising self-assembly of droplets.
Janus droplets were prepared by vortex mixing of three non-mixable liquids, i.e., olive oil, silicone oil and water, in the presence of gold nanoparticles (AuNPs) in the aqueous phase and magnetite nanoparticles (MNPs) in the olive oil. The resulting Pickering emulsions were stabilized by a red-colored AuNP layer at the olive oil/water interface and MNPs at the oil/oil interface. The core–shell droplets can be stimulated by an external magnetic field. Surprisingly, an inner rotation of the silicon droplet is observed when MNPs are fixed at the inner silicon droplet interface. This is the first example of a controlled movement of the inner parts of complex double emulsions by magnetic manipulation via interfacially confined magnetic nanoparticles.
Janus droplets were prepared by vortex mixing of three non-mixable liquids, i.e., olive oil, silicone oil and water, in the presence of gold nanoparticles (AuNPs) in the aqueous phase and magnetite nanoparticles (MNPs) in the olive oil. The resulting Pickering emulsions were stabilized by a red-colored AuNP layer at the olive oil/water interface and MNPs at the oil/oil interface. The core–shell droplets can be stimulated by an external magnetic field. Surprisingly, an inner rotation of the silicon droplet is observed when MNPs are fixed at the inner silicon droplet interface. This is the first example of a controlled movement of the inner parts of complex double emulsions by magnetic manipulation via interfacially confined magnetic nanoparticles.
Hypothesis: Bimetallic magnetite-gold nanostructures are interesting candidates to combine and enhance individual properties of each metal element in catalytic and analytical applications. Microemulsions have been employed in templated synthesis of nanoparticles, and their combination with different types of nanoparticles can further mediate interactions at the water-oil interface, providing new forms of hybrid nanostructures.
Experiments: Reverse water-in-oil microemulsions of droplet sizes below 50 nm were prepared from ternary mixtures of Aerosol-OT (AOT) as surfactant, incorporating 4 nm sized superparamagnetic nanoparticles (MNPs) to the hexane-pentanol oil phase and 5 nmsized polyethyleneimine-stabilized gold nanoparticles (Au(PEI)-NPs) to the water phase. The resulting isotropic L-2 phase, Winsor phases and organized nanostructures were investigated using conductometry, calorimetry, UV-Vis spectroscopy, cryoSEM and HRTEM.
Findings: Droplet-droplet interactions, morphology and surfactant film properties of AOT microemulsions could be modulated in different ways by the presence of the different nanoparticles from each liquid phase. Additionally, phase separation into Winsor phases allows the formation upon solvent evaporation of films with bimetallic heterostructures on the micrometer scale. This demonstrates a new way of nanoparticle templated assembly at liquid interfaces by assisted interactions between microemulsions and nanoparticles, as a promising strategy to obtain thin films of small, isotropic nanoparticles with hierarchical ordering.
Surface self-assembly of spherical nanoparticles of sizes below 10 nm into hierarchical heterostructures is under arising development despite the inherent difficulties of obtaining complex ordering patterns on a larger scale. Due to template-mediated interactions between oil-dispersible superparamagnetic nanoparticles (MNPs) and polyethylenimine- stabilized gold nanoparticles (Au(PEI)NPs) at the water-oil interface of microemulsions, complex nanostructured films can be formed. Characterization of the reverse microemulsion phase by UV-vis absorption revealed the formation of heteroclusters from Winsor type II phases (WPII) using Aerosol-OT (AOT) as the surfactant. SAXS measurements verify the mechanism of initial nanoparticle clustering in defined dimensions. XPS suggested an influence of AOT at the MNP surface. Further, cryo-SEM and TEM visualization demonstrated the elongation of the reverse microemulsions into cylindrical, wormlike structures, which subsequently build up larger nanoparticle superstructure arrangements. Such WPII phases are thus proven to be a new form of soft template, mediating the self-assembly of different nanoparticles in hierarchical network-like filaments over a substrate during solvent evaporation.
The adsorption of protonated L-cysteine onto Au(111) surface was studied via molecular dynamics method. The detailed examination of trajectories reveals that a couple of picoseconds need to be strongly adsorbed at the gold surface via L-cysteine's sulfur and oxygen atoms. The average distances of L-cysteine's adsorbed sulfur and oxygen from gold plane are-2.7 angstrom and-3.2 angstrom, correspondingly. We found that the adsorption of L-cysteine takes place preferentially at bridge site with possibility of-82%. Discussing the conformation features of protonated L-cysteine, we consider that the most stable conformation of protonated L-cysteine is "reverse boat" position, where sulfur and oxygen pointed down to the gold surface, while the amino group is far from the gold surface.
Hydrogels with a hierarchical structure were prepared from a new highly water-soluble crosslinker N,N,N',N'-tetramethyl-N,N'-bis(2-ethylmethacrylate)-propyl-1,3-diammonium dibromide and from the sulfobetaine monomer 2-(N-3-sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate. The free radical polymerization of the two compounds is rapid and yields near-transparent hydrogels with sizes up to 5 cm in diameter. Rheology shows a clear correlation between the monomer-to-crosslinker ratio and the storage and loss moduli of the hydrogels. Cryo-scanning electron microscopy, low-field nuclear magnetic resonance (NMR) spectroscopy, and small-angle X-ray scattering show that the gels have a hierarchical structure with features spanning the nanometer to the sub-millimeter scale. The NMR study is challenged by the marked inhomogeneity of the gels and the complex chemical structure of the sulfobetaine monomer. NMR spectroscopy shows how these complications can be addressed via a novel fitting approach that considers the mobility gradient along the side chain of methacrylate-based monomers.
New cryogels for selective dye removal from aqueous solution were prepared by free radical polymerization from the highly water-soluble crosslinker N,N,N’,N’-tetramethyl-N,N’-bis(2-ethylmethacrylate)-propyl-1,3-diammonium dibromide and the sulfobetaine monomer 2-(N-3-sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate. The resulting white and opaque cryogels have micrometer sized pores with a smaller substructure. They adsorb methyl orange (MO) but not methylene blue (MB) from aqueous solution. Mixtures of MO and MB can be separated through selective adsorption of the MO to the cryogels while the MB remains in solution. The resulting cryogels are thus candidates for the removal of hazardous organic substances, as exemplified by MO and MB, from water. Clearly, it is possible that the cryogels are also potentially interesting for removal of other compounds such as pharmaceuticals or pesticides, but this must be investigated further.
New cryogels for selective dye removal from aqueous solution were prepared by free radical polymerization from the highly water-soluble crosslinker N,N,N’,N’-tetramethyl-N,N’-bis(2-ethylmethacrylate)-propyl-1,3-diammonium dibromide and the sulfobetaine monomer 2-(N-3-sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate. The resulting white and opaque cryogels have micrometer sized pores with a smaller substructure. They adsorb methyl orange (MO) but not methylene blue (MB) from aqueous solution. Mixtures of MO and MB can be separated through selective adsorption of the MO to the cryogels while the MB remains in solution. The resulting cryogels are thus candidates for the removal of hazardous organic substances, as exemplified by MO and MB, from water. Clearly, it is possible that the cryogels are also potentially interesting for removal of other compounds such as pharmaceuticals or pesticides, but this must be investigated further.
A surface modification of ultraflat gold nanotriangles (AuNTs) with different shaped nanoparticles is of special relevance for surface-enhanced Raman scattering (SERS) and the photo-catalytic activity of plasmonic substrates. Therefore, different approaches are used to verify the flat platelet morphology of the AuNTs by oriented overgrowth with metal nanoparticles. The most important part for the morphological transformation of the AuNTs is the coating layer, containing surfactants or polymers. By using well established AuNTs stabilized by a dioctyl sodium sulfosuccinate (AOT) bilayer, different strategies of surface modification with noble metal nanoparticles are possible. On the one hand undulated superstructures were synthesized by in situ growth of hemispherical gold nanoparticles in the polyethyleneimine (PEI)-coated AOT bilayer of the AuNTs. On the other hand spiked AuNTs were obtained by a direct reduction of Au³⁺ ions in the AOT double layer in presence of silver ions and ascorbic acid as reducing agent. Additionally, crumble topping of the smooth AuNTs can be realized after an exchange of the AOT bilayer by hyaluronic acid, followed by a silver-ion mediated reduction with ascorbic acid. Furthermore, a decoration with silver nanoparticles after coating the AOT bilayer with the cationic surfactant benzylhexadecyldimethylammonium chloride (BDAC) can be realized. In that case the ultraviolet (UV)-absorption of the undulated Au@Ag nanoplatelets can be tuned depending on the degree of decoration with silver nanoparticles. Comparing the Raman scattering data for the plasmon driven dimerization of 4-nitrothiophenol (4-NTP) to 4,4′-dimercaptoazobenzene (DMAB) one can conclude that the most important effect of surface modification with a 75 times higher enhancement factor in SERS experiments becomes available by decoration with gold spikes.