| 1. |
- Eves, Ben J., et al.
(författare)
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Elongation rate and average length of amyloid fibrils in solution using isotope-labelled small-angle neutron scattering
- 2021
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Ingår i: RSC Chemical Biology. - : Royal Society of Chemistry (RSC). - 2633-0679. ; 2:4, s. 1232-1238
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a solution method that allows both elongation rate and average fibril length of assembling amyloid fibrils to be estimated. The approach involves acquisition of real-time neutron scattering data during the initial stages of seeded growth, using contrast matched buffer to make the seeds effectively invisible to neutrons. As deuterated monomers add on to the seeds, the labelled growing ends give rise to scattering patterns that we model as cylinders whose increase in length with time gives an elongation rate. In addition, the absolute intensity of the signal can be used to determine the number of growing ends per unit volume, which in turn provides an estimate of seed length. The number of ends did not change significantly during elongation, demonstrating that any spontaneous or secondary nucleation was not significant compared with growth on the ends of pre-existing fibrils, and in addition providing a method of internal validation for the technique. Our experiments on initial growth of alpha synuclein fibrils using 1.2 mg ml-1 seeds in 2.5 mg ml-1 deuterated monomer at room temperature gave an elongation rate of 6.3 ± 0.5 Å min-1, and an average seed length estimate of 4.2 ± 1.3 μm. This journal is
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| 2. |
- Squires, Adam M., et al.
(författare)
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Preparation of Films of a Highly Aligned Lipid Cubic Phase
- 2013
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 29:6, s. 1726-1731
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a method by which we can produce an oriented film of an inverse bicontinuous cubic phase (QII,D) formed by the lipid monoolein (MO). By starting with the lipid as a disordered precursor (the L3 phase) in the presence of butanediol, we can obtain a film of the QII,D phase showing a high degree of in-plane orientation by controlled dilution of the sample under shear within a linear flow cell. We demonstrate that the direction of orientation of the film is different from that found in the oriented bulk material that we have reported previously; therefore, we can now reproducibly form QII,D D samples oriented with either the [110] or the [100] axis aligned in the flow direction depending on the method of preparation. The deposition of MO as a film, via a moving fluid−air interface that leaves a coating of MO in the L3 phase on the capillary wall, leads to a sample in the [110] orientation. This contrasts with the bulk material that we have previously demonstrated to be oriented in the [100] direction, arising from flow producing an oriented bulk slug of material within the capillary tube. The bulk sample contains significant amounts of residual butanediol, which can be estimated from the lattice parameter of the QII,D phase obtained. The sample orientation and lattice parameters are determined from synchrotron small-angle X-ray scattering patterns and confirmed by simulations. This has potential applications in the production of template materials and the growth of protein crystals for crystallography as well as deepening our understanding of the mechanisms underlying the behavior of lyotropic liquid-crystal phases.
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| 3. |
- Seddon, Annela M., et al.
(författare)
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A Highly Oriented Cubic Phase Formed by Lipids under Shear
- 2011
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 133:Online August 8, 2011, s. 13860-13863
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the formation of a macroscopically oriented inverse bicontinuous cubic (QII) lipid phase from a sponge (L3) phase by controlled hydration during shear flow. The L3 phase was the monoolein/butanediol/water system; the addition of water reduces the butanediol concentration, inducing the formation of a diamond (QIID) cubic phase, which is oriented by the shear flow. The phenomenon was reproduced in both capillary and Couette geometries, indicating that this represents a robust general route for the production of highly aligned bulkQII samples, with applications in nanomaterial templating and protein research.
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| 4. |
- Seddon, Annela M., et al.
(författare)
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Control of Nanomaterial Self-Assembly in Ultrasonically Levitated Droplets
- 2016
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Ingår i: The Journal of Physical Chemistry Letters. - 1948-7185. ; 7:7, s. 1341-1345
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that acoustic trapping can be used to levitate and manipulate droplets of soft matter, in particular, lyotropic mesophases formed from selfassembly of different surfactants and lipids, which can be analyzed in a contact-less manner by X-ray scattering in a controlled gas-phase environment. On the macroscopic length scale, the dimensions and the orientation of the particle are shaped by the ultrasonic field, while on the microscopic length scale the nanostructure can be controlled by varying the humidity of the atmosphere around the droplet. We demonstrate levitation and in situ phase transitions of micellar, hexagonal, bicontinuous cubic, and lamellar phases. Thetechnique opens up a wide range of new experimental approaches of fundamentalimportance for environmental, biological, and chemical research.
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| 5. |
- Seddon, Annela M., et al.
(författare)
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Experimental Confirmation of Transformation Pathways between Inverse Double Diamond and Gyroid Cubic Phases
- 2014
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 30:20, s. 5705-5710
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Tidskriftsartikel (refereegranskat)abstract
- A macroscopically oriented double diamond inverse bicontinuous cubic phase (Q(II)(D)) of the lipid glycerol monooleate is reversibly converted into a gyroid phase (Q(II)(G)). The initial Q(II)(D) phase is prepared in the form of a film coating the inside of a capillary, deposited under flow, which produces a sample uniaxially oriented with a < 110 > axis parallel to the symmetry axis of the sample. A transformation is induced by replacing the water within the capillary tube with a solution of poly(ethylene glycol), which draws water out of the Q(II)(D) sample by osmotic stress. This converts the Q(II)(D) phase into a Q(II)(G) phase with two coexisting orientations, with the < 100 > and < 111 > axes parallel to the symmetry axis, as demonstrated by small-angle X-ray scattering. The process can then be reversed, to recover the initial orientation of Q(II)(D) phase. The epitaxial relation between the two oriented mesophases is consistent with topology-preserving geometric pathways that have previously been hypothesized for the transformation. Furthermore, this has implications for the production of macroscopically oriented Q(II)(G) phases, in particular with applications as nanomaterial templates.
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