Influence of salt on the solution dynamics of a phosphorylcholine-based polyzwitterion

Zhenyu J. Zhang, Peter Jeppe Madsen, Nicholas J. Warren, Matthew Mears, Graham J. Leggett, Andrew L. Lewis, Mark Geoghegan

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Abstract

The diffusion of a polyzwitterion, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), in aqueous solution containing different alkali halides was studied by fluorescence correlation spectroscopy at single molecule level. It was found that the halide anion has a greater effect on the radius of zwitterionic PMPC molecules than alkali cations, which is due to the mechanism by which PMPC molecules interact with the surrounding hydrogen bond network of water molecules and adsorbed ions. With the addition of salt, the size of PMPC remains constant while its diffusion coefficient is reduced slightly, although larger cations (e.g. K+) result in slightly increased diffusion coefficient for 1 M potassium chloride-based solutions. This enhanced diffusion coefficient is attributed to the decrease in the viscosity of the aqueous solution on the addition of salt. When the counter-ion was varied in potassium-based salts, different effects were observed for different anions, resulting a reduction in the diffusion coefficient as a function of salt concentration. This reduction was modest for KBr, but significant for KI. Overall, no discernible changes were observed as the size of the PMPC coil was varied, except in case of KI for which a significant increase was observed at higher ionic strength. Divalent cations (Ca2+ and Mg2+, produced similar effects to those found for monovalent cations. These effects are explained by the interaction of PMPC with the hydrogen bond network of water molecules and with the adsorbed ions.
Original languageEnglish
JournalEuropean Polymer Journal
Volume87
Pages (from-to)449-457
Number of pages9
ISSN0014-3057
DOIs
Publication statusPublished - 2017
Externally publishedYes

Bibliographical note

This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Keywords

  • Solution dynamics
  • Diffusion
  • Zwitterionic
  • Phosphorylcholine
  • Polyelectrolyte

Cite this

Zhang, Zhenyu J. ; Jeppe Madsen, Peter ; Warren, Nicholas J. ; Mears, Matthew ; Leggett, Graham J. ; Lewis, Andrew L. ; Geoghegan, Mark. / Influence of salt on the solution dynamics of a phosphorylcholine-based polyzwitterion. In: European Polymer Journal. 2017 ; Vol. 87. pp. 449-457.
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abstract = "The diffusion of a polyzwitterion, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), in aqueous solution containing different alkali halides was studied by fluorescence correlation spectroscopy at single molecule level. It was found that the halide anion has a greater effect on the radius of zwitterionic PMPC molecules than alkali cations, which is due to the mechanism by which PMPC molecules interact with the surrounding hydrogen bond network of water molecules and adsorbed ions. With the addition of salt, the size of PMPC remains constant while its diffusion coefficient is reduced slightly, although larger cations (e.g. K+) result in slightly increased diffusion coefficient for 1 M potassium chloride-based solutions. This enhanced diffusion coefficient is attributed to the decrease in the viscosity of the aqueous solution on the addition of salt. When the counter-ion was varied in potassium-based salts, different effects were observed for different anions, resulting a reduction in the diffusion coefficient as a function of salt concentration. This reduction was modest for KBr, but significant for KI. Overall, no discernible changes were observed as the size of the PMPC coil was varied, except in case of KI for which a significant increase was observed at higher ionic strength. Divalent cations (Ca2+ and Mg2+, produced similar effects to those found for monovalent cations. These effects are explained by the interaction of PMPC with the hydrogen bond network of water molecules and with the adsorbed ions.",
keywords = "Solution dynamics, Diffusion, Zwitterionic, Phosphorylcholine, Polyelectrolyte",
author = "Zhang, {Zhenyu J.} and {Jeppe Madsen}, Peter and Warren, {Nicholas J.} and Matthew Mears and Leggett, {Graham J.} and Lewis, {Andrew L.} and Mark Geoghegan",
note = "This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).",
year = "2017",
doi = "10.1016/j.eurpolymj.2016.12.001",
language = "English",
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pages = "449--457",
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Influence of salt on the solution dynamics of a phosphorylcholine-based polyzwitterion. / Zhang, Zhenyu J.; Jeppe Madsen, Peter; Warren, Nicholas J.; Mears, Matthew; Leggett, Graham J.; Lewis, Andrew L.; Geoghegan, Mark.

In: European Polymer Journal, Vol. 87, 2017, p. 449-457.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Influence of salt on the solution dynamics of a phosphorylcholine-based polyzwitterion

AU - Zhang, Zhenyu J.

AU - Jeppe Madsen, Peter

AU - Warren, Nicholas J.

AU - Mears, Matthew

AU - Leggett, Graham J.

AU - Lewis, Andrew L.

AU - Geoghegan, Mark

N1 - This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

PY - 2017

Y1 - 2017

N2 - The diffusion of a polyzwitterion, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), in aqueous solution containing different alkali halides was studied by fluorescence correlation spectroscopy at single molecule level. It was found that the halide anion has a greater effect on the radius of zwitterionic PMPC molecules than alkali cations, which is due to the mechanism by which PMPC molecules interact with the surrounding hydrogen bond network of water molecules and adsorbed ions. With the addition of salt, the size of PMPC remains constant while its diffusion coefficient is reduced slightly, although larger cations (e.g. K+) result in slightly increased diffusion coefficient for 1 M potassium chloride-based solutions. This enhanced diffusion coefficient is attributed to the decrease in the viscosity of the aqueous solution on the addition of salt. When the counter-ion was varied in potassium-based salts, different effects were observed for different anions, resulting a reduction in the diffusion coefficient as a function of salt concentration. This reduction was modest for KBr, but significant for KI. Overall, no discernible changes were observed as the size of the PMPC coil was varied, except in case of KI for which a significant increase was observed at higher ionic strength. Divalent cations (Ca2+ and Mg2+, produced similar effects to those found for monovalent cations. These effects are explained by the interaction of PMPC with the hydrogen bond network of water molecules and with the adsorbed ions.

AB - The diffusion of a polyzwitterion, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), in aqueous solution containing different alkali halides was studied by fluorescence correlation spectroscopy at single molecule level. It was found that the halide anion has a greater effect on the radius of zwitterionic PMPC molecules than alkali cations, which is due to the mechanism by which PMPC molecules interact with the surrounding hydrogen bond network of water molecules and adsorbed ions. With the addition of salt, the size of PMPC remains constant while its diffusion coefficient is reduced slightly, although larger cations (e.g. K+) result in slightly increased diffusion coefficient for 1 M potassium chloride-based solutions. This enhanced diffusion coefficient is attributed to the decrease in the viscosity of the aqueous solution on the addition of salt. When the counter-ion was varied in potassium-based salts, different effects were observed for different anions, resulting a reduction in the diffusion coefficient as a function of salt concentration. This reduction was modest for KBr, but significant for KI. Overall, no discernible changes were observed as the size of the PMPC coil was varied, except in case of KI for which a significant increase was observed at higher ionic strength. Divalent cations (Ca2+ and Mg2+, produced similar effects to those found for monovalent cations. These effects are explained by the interaction of PMPC with the hydrogen bond network of water molecules and with the adsorbed ions.

KW - Solution dynamics

KW - Diffusion

KW - Zwitterionic

KW - Phosphorylcholine

KW - Polyelectrolyte

U2 - 10.1016/j.eurpolymj.2016.12.001

DO - 10.1016/j.eurpolymj.2016.12.001

M3 - Journal article

VL - 87

SP - 449

EP - 457

JO - European Polymer Journal

JF - European Polymer Journal

SN - 0014-3057

ER -