Advanced

Hydrodynamic Forces on Macromolecules Protruding from Lipid Bilayers Due to External Liquid Flows.

Jönsson, Peter LU and Jönsson, Bengt LU (2015) In Langmuir 31(46). p.12708-12718
Abstract
It has previously been observed that an externally applied hydrodynamic shear flow above a fluid lipid bilayer can change the local concentration of macromolecules that are associated with the lipid bilayer. The external liquid flow results in a hydrodynamic force on molecules protruding from the lipid bilayer, causing them to move in the direction of the flow. However, there has been no quantitative study about the magnitude of these forces. We here use finite element simulations to investigate how the magnitude of the external hydrodynamic forces varies with the size and shape of the studied macromolecule. The simulations show that the hydrodynamic force is proportional to the effective hydrodynamic area of the studied molecule, Ahydro,... (More)
It has previously been observed that an externally applied hydrodynamic shear flow above a fluid lipid bilayer can change the local concentration of macromolecules that are associated with the lipid bilayer. The external liquid flow results in a hydrodynamic force on molecules protruding from the lipid bilayer, causing them to move in the direction of the flow. However, there has been no quantitative study about the magnitude of these forces. We here use finite element simulations to investigate how the magnitude of the external hydrodynamic forces varies with the size and shape of the studied macromolecule. The simulations show that the hydrodynamic force is proportional to the effective hydrodynamic area of the studied molecule, Ahydro, multiplied by the mean hydrodynamic shear stress acting on the membrane surface, σhydro. The parameter Ahydro depends on the size and shape of the studied macromolecule above the lipid bilayer and scales with the cross-sectional area of the molecule. We also investigate how hydrodynamic shielding from other surrounding macromolecules decreases Ahydro when the surface coverage of the shielding macromolecules increases. Experiments where the protein streptavidin is anchored to a supported lipid bilayer on the floor of a microfluidic channel were finally performed at three different surface concentrations, Φ = 1%, 6%, and 10%, where the protein is being moved relative to the lipid bilayer by a liquid flow through the channel. From photobleaching measurements of fluorescently labeled streptavidin we found the experimental drift data to be within good accuracy of the simulated results, less than 12% difference, indicating the validity of the results obtained from the simulations. In addition to giving a deeper insight into how a liquid flow can affect membrane-associated molecules in a lipid bilayer, we also see an interesting potential of using hydrodynamic flow experiments together with the obtained results to study the size and the intermolecular forces between macromolecules in membranes and lipid bilayers. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
31
issue
46
pages
12708 - 12718
publisher
The American Chemical Society
external identifiers
  • pmid:26523331
  • wos:000365464200018
  • scopus:84948445288
ISSN
0743-7463
DOI
10.1021/acs.langmuir.5b03421
language
English
LU publication?
yes
id
a99682af-5103-429c-bbc1-ad8397c9348b (old id 8243649)
date added to LUP
2015-12-08 10:13:20
date last changed
2017-01-01 03:54:26
@article{a99682af-5103-429c-bbc1-ad8397c9348b,
  abstract     = {It has previously been observed that an externally applied hydrodynamic shear flow above a fluid lipid bilayer can change the local concentration of macromolecules that are associated with the lipid bilayer. The external liquid flow results in a hydrodynamic force on molecules protruding from the lipid bilayer, causing them to move in the direction of the flow. However, there has been no quantitative study about the magnitude of these forces. We here use finite element simulations to investigate how the magnitude of the external hydrodynamic forces varies with the size and shape of the studied macromolecule. The simulations show that the hydrodynamic force is proportional to the effective hydrodynamic area of the studied molecule, Ahydro, multiplied by the mean hydrodynamic shear stress acting on the membrane surface, σhydro. The parameter Ahydro depends on the size and shape of the studied macromolecule above the lipid bilayer and scales with the cross-sectional area of the molecule. We also investigate how hydrodynamic shielding from other surrounding macromolecules decreases Ahydro when the surface coverage of the shielding macromolecules increases. Experiments where the protein streptavidin is anchored to a supported lipid bilayer on the floor of a microfluidic channel were finally performed at three different surface concentrations, Φ = 1%, 6%, and 10%, where the protein is being moved relative to the lipid bilayer by a liquid flow through the channel. From photobleaching measurements of fluorescently labeled streptavidin we found the experimental drift data to be within good accuracy of the simulated results, less than 12% difference, indicating the validity of the results obtained from the simulations. In addition to giving a deeper insight into how a liquid flow can affect membrane-associated molecules in a lipid bilayer, we also see an interesting potential of using hydrodynamic flow experiments together with the obtained results to study the size and the intermolecular forces between macromolecules in membranes and lipid bilayers.},
  author       = {Jönsson, Peter and Jönsson, Bengt},
  issn         = {0743-7463},
  language     = {eng},
  number       = {46},
  pages        = {12708--12718},
  publisher    = {The American Chemical Society},
  series       = {Langmuir},
  title        = {Hydrodynamic Forces on Macromolecules Protruding from Lipid Bilayers Due to External Liquid Flows.},
  url          = {http://dx.doi.org/10.1021/acs.langmuir.5b03421},
  volume       = {31},
  year         = {2015},
}