Cryo-TEM of soft molecular assemblies

Danino, Dganit

doi:10.1016/j.cocis.2012.10.003

Cited by 152 publications

(126 citation statements)

References 145 publications

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“…The structural analysis presented here was done using advanced cryo-TEM and cryo-SEM, two techniques that preserve the native hydrated state of the complexes and unravel local and global structural details, that combined can conclusively determine the structure at length scales ranging from the nano to the micro-scale [14,15].…”

Section: Resultsmentioning

confidence: 99%

“…The capability to expose both the overall supramolecular structure and the inner assembly details at the nanometer resolution is important to differentiate between cochleates and 1-dimensional nanotubes (tubules) [8,15,17,18]. The morphology of these two structures may appear similar, although, the driving forces to their formation, and their biophysical properties are different: (i) cochleate formation is independent of the lipid transition temperature; (ii) cochleate formation must involve lipids head-group dehydration; (iii) cochleate structure is preserved upon heating above the transition temperature; and (iv) cochleate to liposome transformation occurs due to calcium ion chelation, while tubule to liposome transformation requires heating to above the transition temperature [8,15]. The multi-lamellar assembly of the cochleates as observed by cryo-TEM often resembles that of multi-lamellar tubules; differentiation between the two can be achieved by cryo-SEM analysis, as demonstrated here.…”

Section: Resultsmentioning

confidence: 99%

“…Specimens for cryo-TEM were prepared in the CEVS at 25 °C and 100% relative humidity, as described elsewhere [14,15]. The vitrified specimens were examined with a Philips CM 120 TEM using Gatan 626 or Oxford CT-3500 cooling holders, equilibrated in the microscope to below −171 °C.…”

Section: Cryo-temmentioning

confidence: 99%

See 2 more Smart Citations

Cochleate characterization by cryogenic electron microscopy methods: Cryo-TEM and Cryo-SEM

Hollander

Danino

2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Cochleate characterization by cryogenic electron microscopy methods: Cryo-TEM and Cryo-SEM

Hollander

Danino

2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…Also in neutron or light scattering experiments, linear micelles and branched micelles show similar behavior. So far, the only method that can directly distinguish linear and branched micelles is cryo-TEM [Clausen et al (1992) Danino (2012)]. All these studies have indicated that the first viscosity maximum occurring at a critical salt/surfactant ratio R max is attributed to the transition from linear to branched micelles.…”

Section: Elongational Flow Of Wlm Solutionsmentioning

confidence: 99%

Elongational deformation of wormlike micellar solutions

Sachsenheimer

Oelschlaeger

Müller

et al. 2014

Journal of Rheology

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We have investigated the uniaxial elongation behavior of six different wormlike micelle systems covering a broad range of surfactant concentrations cs and salt/surfactant ratios R using the capillary breakup elongational rheometry (CaBER). In the fast-breaking limit (high cs and R), filament lifetime tfil is controlled by the equilibrium shear modulus G0 and the breakage time λbr obtained from small oscillatory shear according to tfil/G0∝λbr2/3 and relaxation time ratios λe/λs≈1 are found. When reptation dominates (high cs, low R) λe/λs<1 is observed similar as for solutions of covalently bound polymers. In this concentration regime, the micellar structure seems not to be affected by the strong elongational flow. In contrast, high filament lifetimes up to 1000 s and λe/λs values up to 10 are observed at low cs irrespective of R. This indicates the formation of elongation-induced structures (EISs). A minimum viscosity and a minimum initial diameter are required for creating EIS. Additional filament stretching experiments indicate that a critical total deformation has to be exceeded for structure build-up. Finally, our experiments reveal a distinct difference regarding the dependence between solutions of linear and branched micelles of filament lifetime on viscosity suggesting that CaBER is a versatile means to distinguish between these structures.

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“…34 It is to be noted that the value of d is that of a steric bilayer thickness as dened in ref. 32, i.e., containing n w water molecules per phospholipid molecule.…”

Section: Differential Scanning Calorimetry (Dscmentioning

confidence: 99%

Control of the stability and structure of liposomes by means of nanoparticles

et al. 2013

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The interaction of bilayer vesicles with hard nanoparticles is of great relevance to the field of nanotechnology, e.g., its impact on health and safety matters, and also as vesicles are important as delivery vehicles. In this work we describe hybrid systems composed of zwitterionic phospholipid vesicles (DPPC), which are below the phase transition temperature, and added silica nanoparticles (SiNPs) of much smaller size. The initial DPPC unilamellar vesicles, obtained by extrusion, are rather unstable and age but the rate of ageing can be controlled over a large time range by the amount of added SiNPs. For low addition they become destabilized whereas larger amounts of SiNPs enhance the stability largely as confirmed by dynamic light scattering (DLS). z-Potential and DSC measurements confirm the binding of the SiNPs onto the phospholipid vesicles, which stabilizes the vesicles against flocculation by rendering the z-potential more negative. This effect appears above a specific SiNP concentration, and is the result of the adsorption of the negatively charged nanoparticles onto the outer surface of the liposome leading to decorated vesicles as proven by cryogenic transmission electron microscopy (cryo-TEM). Small amounts of surface-adsorbed SiNPs initially lead to a bridging of vesicles thereby enhancing flocculation, while higher amounts render the vesicles much more negatively charged and thereby longtime stable. This stability has an optimum at neutral pH and for low ionic strength. Thus we show that the addition of the SiNPs is a versatile way to control the stability of gel-state phospholipid vesicles and also to modulate their surface structure in a systematic fashion. This is not only of importance for understanding the fundamental interaction between SiNPs and bilayer vesicles, but also with respect to using silica particles as formulation aids for phospholipid dispersions.

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Cryo-TEM of soft molecular assemblies

Cited by 152 publications

References 145 publications

Cochleate characterization by cryogenic electron microscopy methods: Cryo-TEM and Cryo-SEM

Cochleate characterization by cryogenic electron microscopy methods: Cryo-TEM and Cryo-SEM

Elongational deformation of wormlike micellar solutions

Control of the stability and structure of liposomes by means of nanoparticles

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