Abbildung selbstorganisierter Strukturen: Interpretation von TEM‐ und Kryo‐TEM‐Aufnahmen

Friedrich, Heiner; Frederik, Peter M.; Sommerdijk, Nico A. J. M.

doi:10.1002/ange.201001493

Cited by 17 publications

(6 citation statements)

References 123 publications

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“…50 -OSiMePhH] 4 : [(PEO) 50 -OH] 4 (250 mg, 0.028 mmol) was dissolved in dry toluene (10 mL) at 40 8C. After cooling to room temperature, pyridine (0.57 mmol, 50 mL, 20 equiv) and chloro-A C H T U N G T R E N N U N G (methyl)phenylsilane (0.14 mmol, 25 mL, 5 equiv) were added and the reaction mixture was stirred for 24 h at this temperature.…”

Section: Resultsmentioning

confidence: 97%

“…Both in THF/EtOH and in water, cryo-TEM allowed for quasi in situ visualization of the unperturbed vesicles (Figure 4). [49,50] Whereas most literature examples deal with cryo-TEM in aqueous solution, [15] there are few examples of such experiments in organic solvents or solvent mixtures, as shown for toluene [51] and dioxane/THF. [52] Both in THF/EtOH ( Figure 4A) and in water ( Figure 4B), spherical structures with diameters of 100-200 nm can be seen.…”

Section: Resultsmentioning

confidence: 98%

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Responsive Vesicles from the Self‐Assembly of Crystalline‐Coil Polyferrocenylsilane‐block‐Poly(ethylene Oxide) Star‐Block Copolymers

Schacher¹,

Elbert²,

Patra³

et al. 2011

Chemistry A European J

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We demonstrate the synthesis and characterization of star-shaped crystalline-coil block copolymers with four arms consisting of an inner block of poly(ethylene oxide) and an outer semicrystalline compartment of poly(ferrocenyldimethylsilane), [PEO(50) -b-PFDMS(35)](4). The materials were synthesized by transition-metal-catalyzed ring-opening polymerization of dimethylsila[1]ferrocenophane in the presence of silane-functionalized four-arm PEO stars as macroinitiators and they exhibited a moderate polydispersity (PDI≅1.4). Self-assembly in mixtures of THF and different alcohols as selective solvents for the PEO block resulted in the formation of semicrystalline vesicles (ethanol, 1-butanol) or large, rather ill-defined, spherical structures (methanol). Further, both the rate of addition of the selective co-solvent and the overall solvent/non-solvent ratio drastically affected the size and stability of the self-assembled particles. We could also show that a photoacid generator, as a model for an active substance, can be encapsulated and the UV-induced generation of HCl resulted in a straightforward degradation of the organometallic vesicles.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 98%

Responsive Vesicles from the Self‐Assembly of Crystalline‐Coil Polyferrocenylsilane‐block‐Poly(ethylene Oxide) Star‐Block Copolymers

Schacher¹,

Elbert²,

Patra³

et al. 2011

Chemistry A European J

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“…Cryo‐TEM and FF‐TEM technologies are two powerful tools that can enable an unambiguous observation of the surfactant self‐assembly structure in their hydrate state 23. Figure S2 in the Supporting Information shows cryo‐TEM images of a sample solution in different phase regions.…”

Section: Resultsmentioning

confidence: 99%

Interconvertible Self‐Assembly and Rheological Properties of Planar Bilayers and Vesicle Gels in Anionic/Nonionic (CF/CH) Surfactant Solutions

Dong

et al. 2013

Chemistry An Asian Journal

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The surface and bulk properties of aqueous mixtures of nonionic tetraethylene glycol monododecyl ether (C12EO4) and anionic perfluorolauric acid (PFLA) were studied. These mixtures exhibited pronounced synergistic effects in terms of their mixed micellization and rheological properties. Only one type of mixed micelle is formed in dilute mixed solutions. At low PFLA content, with increasing the total surfactant concentration, short thread-like micelles grow to form larger discs. On increasing the amount of PFLA, owing to the fact that the fluctuant planar bilayers of nonionic C12EO4 become charged, vesicle gels that are comprised of densely packed unilamellar and multilamellar vesicles spontaneously form, in which the fluorocarbon chains in the bilayers are in a fluid state at room temperature. The elastic properties and the yield stress of the lamellar solutions largely increase upon the addition of small amounts of PFLA and they then pass through a maximum at a saturation of effective membrane charge density. Interestingly, increasing the pH value of the gels causes a backward transition from stiff vesicles to flexible planar bilayers. On increasing the amount of NaOH, the bilayers exhibit greater flexibility, owing to the decrease in membrane charges, along with a large decrease in the solution viscosity and their elastic properties. The combination of strong stability of the vesicle gels with the interconvertible transition of bilayers and vesicles is expected to be of practical use for controlled drug delivery and release.

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“…The cryo‐TEM technique minimizes preparation artifacts by vitrification (ultra‐fast cooling) of the (aqueous) sample solution and allows for a direct visualization of the native assembly structure in the fully hydrated state 22–24. In the cryo‐TEM images of the (PLA/HSA) 3 nanotubes (Figure 3 a–d), four characteristics are instantly recognizable: 1) The O.D.…”

Section: Resultsmentioning

confidence: 99%

Human Serum Albumin Nanotubes with Esterase Activity

Komatsu

Sato

Boettcher

2011

Chemistry An Asian Journal

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A nanocylindrical wall structure was obtained by layer-by-layer (LbL) assembly of poly-L-arginine (PLA) and human serum albumin (HSA) and characterized by scanning electron microscopy (SEM), scanning force microscopy (SFM), and cryogenic transmission electron microscopy (cryo-TEM). SEM and SFM measurements of a lyophilized powder of (PLA/HSA)(3) nanotubes yielded images of round, chimney-like architectures with approximately 100 nm wall thickness. Cryo-TEM images of the hydrated sample revealed that the tube walls are composed of densely packed HSA molecules. Moreover, when small-angle X-ray scattering was used to characterize the individual PLA and HSA components in aqueous solutions, maximum diameters of approximately 28 nm and 8 nm were obtained, respectively. These values indicate the minimum thickness of wall layers consisting of PLA and HSA. It can also be concluded from SEM as well as from cryo-TEM images that the protein cylinders are considerably swollen in the presence of water. Furthermore, HSA retains esterase activity if assembled in nanotubes, as indicated by measurements of para-nitrophenyl acetate hydrolysis under semi-physiological conditions (pH 7.4, 22 °C). The enzyme activity parameters (Michaelis constant, K(m), and catalytic constant, k(cat)) were comparable to those of free HSA.

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Abbildung selbstorganisierter Strukturen: Interpretation von TEM‐ und Kryo‐TEM‐Aufnahmen

Cited by 17 publications

References 123 publications

Responsive Vesicles from the Self‐Assembly of Crystalline‐Coil Polyferrocenylsilane‐block‐Poly(ethylene Oxide) Star‐Block Copolymers

Responsive Vesicles from the Self‐Assembly of Crystalline‐Coil Polyferrocenylsilane‐block‐Poly(ethylene Oxide) Star‐Block Copolymers

Interconvertible Self‐Assembly and Rheological Properties of Planar Bilayers and Vesicle Gels in Anionic/Nonionic (CF/CH) Surfactant Solutions

Human Serum Albumin Nanotubes with Esterase Activity

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