Your browser has javascript turned off or blocked. This will lead to some parts of our website to not work properly or at all. Turn on javascript for best performance.

The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Portrait of Jonas Tegenfeldt. Photo: Kennet Ruona

Jonas Tegenfeldt

Professor, Coordinator Nanobiology & Neuronanoscience

Portrait of Jonas Tegenfeldt. Photo: Kennet Ruona

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

Author

  • G. Ohlsson
  • S. R. Tabaei
  • Jason Beech
  • Jan Kvassman
  • Urban Johanson
  • Per Kjellbom
  • Jonas Tegenfeldt
  • Fredrik Höök

Summary, in English

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.

Department/s

  • Solid State Physics
  • Biochemistry and Structural Biology
  • NanoLund

Publishing year

2012

Language

English

Pages

4635-4643

Publication/Series

Lab on a Chip

Volume

12

Issue

22

Document type

Journal article

Publisher

Royal Society of Chemistry

Topic

  • Condensed Matter Physics
  • Biological Sciences

Status

Published

ISBN/ISSN/Other

  • ISSN: 1473-0189