Using small-angle scattering and contrast matching to understand molecular packing in low molecular weight gels

Emily R. Draper, Bart Dietrich, Kate McAulay, Christopher Brasnett, Haleh Abdizadeh, Ilias Patmanidis, Siewert J Marrink, Hao Su, Honggang Cui, Ralf Schweins, Annela M Seddon, Dave J Adams

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Abstract

It is difficult to determine exactly the molecular packing in the aggregates in low
molecular weight gels. Attempts to understand the packing have been made using X-ray diffraction, but there are complications with drying and questions as to whether the crystal structures represent the packing in the gel phase. Here, we exploit contrast matching in small-angle neutron scattering experiments. By preparing selectively deuterated analogs of the same molecule, the scattering from that section of the molecule decreases compared with the hydrogenated molecule. We examine packing in the pre-gelled solutions at high pH and in the gels at low pH. The data from the final gels show a lack of specific order in the aggregates that form the gel matrix. The packing in these systems is not well ordered in the gel state and so implies that it is likely that current models and cartoons are not correct.
Original languageEnglish
Number of pages16
JournalMatter
DOIs
Publication statusPublished - 29 Jan 2020

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low molecular weights
gels
scattering
molecules
drying
neutron scattering
analogs
crystal structure
matrices
diffraction
x rays

Keywords

  • hydrogel
  • SANS
  • SAXS
  • gel
  • peptide

Cite this

Draper, Emily R. ; Dietrich, Bart ; McAulay, Kate ; Brasnett, Christopher ; Abdizadeh, Haleh ; Patmanidis, Ilias ; Marrink, Siewert J ; Su, Hao ; Cui, Honggang ; Schweins, Ralf ; Seddon, Annela M ; Adams, Dave J. / Using small-angle scattering and contrast matching to understand molecular packing in low molecular weight gels. In: Matter. 2020.
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title = "Using small-angle scattering and contrast matching to understand molecular packing in low molecular weight gels",
abstract = "It is difficult to determine exactly the molecular packing in the aggregates in lowmolecular weight gels. Attempts to understand the packing have been made using X-ray diffraction, but there are complications with drying and questions as to whether the crystal structures represent the packing in the gel phase. Here, we exploit contrast matching in small-angle neutron scattering experiments. By preparing selectively deuterated analogs of the same molecule, the scattering from that section of the molecule decreases compared with the hydrogenated molecule. We examine packing in the pre-gelled solutions at high pH and in the gels at low pH. The data from the final gels show a lack of specific order in the aggregates that form the gel matrix. The packing in these systems is not well ordered in the gel state and so implies that it is likely that current models and cartoons are not correct.",
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Draper, ER, Dietrich, B, McAulay, K, Brasnett, C, Abdizadeh, H, Patmanidis, I, Marrink, SJ, Su, H, Cui, H, Schweins, R, Seddon, AM & Adams, DJ 2020, 'Using small-angle scattering and contrast matching to understand molecular packing in low molecular weight gels', Matter. https://doi.org/10.1016/j.matt.2019.12.028

Using small-angle scattering and contrast matching to understand molecular packing in low molecular weight gels. / Draper, Emily R.; Dietrich, Bart; McAulay, Kate; Brasnett, Christopher; Abdizadeh, Haleh; Patmanidis, Ilias ; Marrink, Siewert J; Su, Hao; Cui, Honggang; Schweins, Ralf ; Seddon, Annela M; Adams, Dave J.

In: Matter, 29.01.2020.

Research output: Contribution to journalArticle

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T1 - Using small-angle scattering and contrast matching to understand molecular packing in low molecular weight gels

AU - Draper, Emily R.

AU - Dietrich, Bart

AU - McAulay, Kate

AU - Brasnett, Christopher

AU - Abdizadeh, Haleh

AU - Patmanidis, Ilias

AU - Marrink, Siewert J

AU - Su, Hao

AU - Cui, Honggang

AU - Schweins, Ralf

AU - Seddon, Annela M

AU - Adams, Dave J

N1 - Acceptance from webpage OA article - Corrected proof uploaded; update with VoR upon publication. Keep epub date (29 Jan 2020). 4/2/20 DC

PY - 2020/1/29

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N2 - It is difficult to determine exactly the molecular packing in the aggregates in lowmolecular weight gels. Attempts to understand the packing have been made using X-ray diffraction, but there are complications with drying and questions as to whether the crystal structures represent the packing in the gel phase. Here, we exploit contrast matching in small-angle neutron scattering experiments. By preparing selectively deuterated analogs of the same molecule, the scattering from that section of the molecule decreases compared with the hydrogenated molecule. We examine packing in the pre-gelled solutions at high pH and in the gels at low pH. The data from the final gels show a lack of specific order in the aggregates that form the gel matrix. The packing in these systems is not well ordered in the gel state and so implies that it is likely that current models and cartoons are not correct.

AB - It is difficult to determine exactly the molecular packing in the aggregates in lowmolecular weight gels. Attempts to understand the packing have been made using X-ray diffraction, but there are complications with drying and questions as to whether the crystal structures represent the packing in the gel phase. Here, we exploit contrast matching in small-angle neutron scattering experiments. By preparing selectively deuterated analogs of the same molecule, the scattering from that section of the molecule decreases compared with the hydrogenated molecule. We examine packing in the pre-gelled solutions at high pH and in the gels at low pH. The data from the final gels show a lack of specific order in the aggregates that form the gel matrix. The packing in these systems is not well ordered in the gel state and so implies that it is likely that current models and cartoons are not correct.

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