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Solute transport on the sub 100 ms scale across the lipid bilayer membrane of individual proteoliposomes

Ohlsson, G.; Tabaei, S. R.; Beech, Jason LU ; Kvassman, Jan LU ; Johanson, Urban LU ; Kjellbom, Per LU ; Tegenfeldt, Jonas LU and Höök, Fredrik LU (2012) In Lab on A Chip 12(22). p.4635-4643
Abstract
Screening assays designed to probe ligand and drug-candidate regulation of membrane proteins responsible for ion-translocation across the cell membrane are wide spread, while efficient means to screen membrane-protein facilitated transport of uncharged solutes are sparse. We report on a microfluidic-based system to monitor transport of uncharged solutes across the membrane of multiple (>100) individually resolved surface-immobilized liposomes. This was accomplished by rapidly switching (<10 ms) the solution above dye-containing liposomes immobilized on the floor of a microfluidic channel. With liposomes encapsulating the pH-sensitive dye carboxyfluorescein (CF), internal changes in pH induced by transport of a weak acid (acetic acid)... (More)
Screening assays designed to probe ligand and drug-candidate regulation of membrane proteins responsible for ion-translocation across the cell membrane are wide spread, while efficient means to screen membrane-protein facilitated transport of uncharged solutes are sparse. We report on a microfluidic-based system to monitor transport of uncharged solutes across the membrane of multiple (>100) individually resolved surface-immobilized liposomes. This was accomplished by rapidly switching (<10 ms) the solution above dye-containing liposomes immobilized on the floor of a microfluidic channel. With liposomes encapsulating the pH-sensitive dye carboxyfluorescein (CF), internal changes in pH induced by transport of a weak acid (acetic acid) could be measured at time scales down to 25 ms. The applicability of the set up to study biological transport reactions was demonstrated by examining the osmotic water permeability of human aquaporin (AQP5) reconstituted in proteoliposomes. In this case, the rate of osmotic-induced volume changes of individual proteoliposomes was time resolved by imaging the self quenching of encapsulated calcein in response to an osmotic gradient. Single-liposome analysis of both pure and AQP5-containing liposomes revealed a relatively large heterogeneity in osmotic permeability. Still, in the case of AQP5-containing liposomes, the single liposome data suggest that the membrane-protein incorporation efficiency depends on liposome size, with higher incorporation efficiency for larger liposomes. The benefit of low sample consumption and automated liquid handling is discussed in terms of pharmaceutical screening applications. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Lab on A Chip
volume
12
issue
22
pages
4635 - 4643
publisher
Royal Society of Chemistry
external identifiers
  • wos:000310865200007
  • scopus:84867521935
ISSN
1473-0189
DOI
10.1039/c2lc40518k
language
English
LU publication?
yes
id
5eebfd07-770b-4156-a991-c58f0f9cd627 (old id 3224882)
date added to LUP
2012-12-14 19:44:41
date last changed
2017-02-02 10:25:51
@article{5eebfd07-770b-4156-a991-c58f0f9cd627,
  abstract     = {Screening assays designed to probe ligand and drug-candidate regulation of membrane proteins responsible for ion-translocation across the cell membrane are wide spread, while efficient means to screen membrane-protein facilitated transport of uncharged solutes are sparse. We report on a microfluidic-based system to monitor transport of uncharged solutes across the membrane of multiple (&gt;100) individually resolved surface-immobilized liposomes. This was accomplished by rapidly switching (&lt;10 ms) the solution above dye-containing liposomes immobilized on the floor of a microfluidic channel. With liposomes encapsulating the pH-sensitive dye carboxyfluorescein (CF), internal changes in pH induced by transport of a weak acid (acetic acid) could be measured at time scales down to 25 ms. The applicability of the set up to study biological transport reactions was demonstrated by examining the osmotic water permeability of human aquaporin (AQP5) reconstituted in proteoliposomes. In this case, the rate of osmotic-induced volume changes of individual proteoliposomes was time resolved by imaging the self quenching of encapsulated calcein in response to an osmotic gradient. Single-liposome analysis of both pure and AQP5-containing liposomes revealed a relatively large heterogeneity in osmotic permeability. Still, in the case of AQP5-containing liposomes, the single liposome data suggest that the membrane-protein incorporation efficiency depends on liposome size, with higher incorporation efficiency for larger liposomes. The benefit of low sample consumption and automated liquid handling is discussed in terms of pharmaceutical screening applications.},
  author       = {Ohlsson, G. and Tabaei, S. R. and Beech, Jason and Kvassman, Jan and Johanson, Urban and Kjellbom, Per and Tegenfeldt, Jonas and Höök, Fredrik},
  issn         = {1473-0189},
  language     = {eng},
  number       = {22},
  pages        = {4635--4643},
  publisher    = {Royal Society of Chemistry},
  series       = {Lab on A Chip},
  title        = {Solute transport on the sub 100 ms scale across the lipid bilayer membrane of individual proteoliposomes},
  url          = {http://dx.doi.org/10.1039/c2lc40518k},
  volume       = {12},
  year         = {2012},
}