Study summary · research use only
Phase segregation of polymerizable lipids to construct filters for separating lipid-membrane-embedded species
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
This study used phase segregation of lipid mixtures containing a polymerizable diacetylene phospholipid (DiynePC) and a nonpolymerizable phospholipid (DOPC) to construct filter barrier structures in supported lipid bilayers. The abstract explains that UV exposure crosslinked DiynePC-rich domains while DOPC-rich regions were removed by detergent, creating voids, and that microfluidic laminar flow and hydrodynamic shear were used to transport membrane-embedded species from a feed region to a filter region. Varying the DiynePC/DOPC molar ratio from 60/40 to 80/20 adjusted the cutoff size: at 60/40 both model species penetrated, at 70/30 only the smaller Texas Red DHPE penetrated, and at 80/20 neither penetrated. The authors report tunable-cutoff filter fabrication.
Abstract
Supported lipid bilayer (SLB) platforms have been developed to transport and separate membrane-embedded species in the species' native bilayer environment. In this study, we used the phase segregation phenomenon of lipid mixtures containing a polymerizable diacetylene phospholipid, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DiynePC), and a nonpolymerizable phospholipid, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), to create filter barrier structures in SLBs. Upon exposing the phase segregated samples to UV light, the DiynePC-rich domains could become crosslinked and remain fixed on the surface of the support, while the DOPC-rich regions, where no crosslinking could happen, could be removed later by detergent washing, and thus became the void regions in the filter. During the filter fabrication process, we used the laminar flow configuration in a microfluidic channel to control the spatial locations of the feed region and filter region in the SLB. The flow in a microfluidic channel was also used to apply a strong hydrodynamic shear stress to the SLB to transport the membrane-embedded species from the feed region to the filter region. We varied the DiynePC/DOPC molar ratio from 60/40 to 80/20 to adjust the cutoff size of the filter barriers and used two model membrane-embedded species of different sizes to examine the filtering capability. One of the model species, Texas Red 1,2-dihexa-decanoyl-sn-glycero-3-phosphoethanolamine triethylammonium salt (Texas Red DHPE), had a single-lipid size, and the other species, cholera toxin subunit B-GM1 complex, had a multilipid size. When the DiynePC/DOPC molar ratio was 60/40, both species had high penetration ratios in the filter region. However, when the ratio was increased to 70/30, only the Texas Red DHPE, which was the smaller of the two model species, could penetrate the filter to a considerable extent. When the ratio was increased to 80/20, neither of the model species could penetrate the filter region. The results showed the possibility of using phase segregation of a mixture containing a polymerizable lipid and a nonpolymerizable lipid to fabricate filter barrier structures with tunable cutoff sizes in SLBs.
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