ac4006952_si_001.pdf (1.04 MB)
Two-Dimensional Continuous Extraction in Multiphase Lipid Bilayers To Separate, Enrich, and Sort Membrane-Bound Species
journal contribution
posted on 2013-07-16, 00:00 authored by Ling Chao, Mark J. Richards, Chih-Yun Hsia, Susan DanielA new method is presented
to separate, enrich, and sort membrane-bound
biomolecules based on their affinity for different coexisting lipid
phases in a supported lipid bilayer using a two-dimensional, continuous
extraction procedure. Analogous to classic liquid–liquid phase
extraction, we created two distinct lipid phases in our planar membrane
system: a liquid-ordered (lo) phase and
a liquid-disordered (ld) phase arranged
in parallel stripes inside a microfluidic device. Membrane-bound biomolecules
in an adjacent supported lipid bilayer are convected in plane along
the microfluidic channel and brought into contact with a different
lipid phase using hydrodynamic force. A mixture of two lipid species,
a glycolipid and a phospholipid, with known affinities for the two
lipid phases employed here are used to demonstrate continuous extraction
of the lipid-microdomain preferring glycolipid to the lo phase, while the phospholipid remains primarily in the ld phase. In this demonstration, we characterize
the performance of this affinity-based separation device by building
models to describe the velocity profile and transport in the two-phase
coexistent membrane. We then characterize the impact of residence
time on the extraction yield of each species. This new procedure sorts
membrane species on the basis of chemical properties and affinities
for specific lipid phases within a membrane environment near physiological
conditions, critical for extending this method to the separation of
lipid-linked proteins and transmembrane proteins while minimizing
denaturation. This platform could facilitate the separation and identification
of lipid membrane domain residents, or the characterization of changes
in membrane affinity due to post-translational modifications or environmental
conditions.