title: Shaped apertures in photoresist films enhance the lifetime and mechanical stability of suspended lipid bilayers.
abstract: Planar lipid bilayers suspended in apertures provide a controlled environment for ion channel studies. However, short lifetimes and poor mechanical stability of suspended bilayers limit the experimental throughput of bilayer electrophysiology experiments. Although bilayers are more stable in smaller apertures, ion channel incorporation through vesicle fusion with the suspended bilayer becomes increasingly difficult. In an alternative bilayer stabilization approach, we have developed shaped apertures in SU8 photoresist that have tapered sidewalls and a minimum diameter between 60 and 100 μm. Bilayers formed at the thin tip of these shaped apertures, either with the painting or the folding method, display drastically increased lifetimes, typically >20 h, and mechanical stability, being able to withstand extensive perturbation of the buffer solution. Single-channel electrical recordings of the peptide alamethicin and of the proteoliposome-delivered potassium channel KcsA demonstrate channel conductance with low noise, made possible by the small capacitance of the 50 μm thick SU8 septum, which is only thinned around the aperture, and unimpeded proteoliposome fusion, enabled by the large aperture diameter. We anticipate that these shaped apertures with micrometer edge thickness can substantially enhance the throughput of channel characterization by bilayer lipid membrane electrophysiology, especially in combination with automated parallel bilayer platforms.
authors.affiliation: Electronics and Computer Science, University of Southampton, Southampton, United Kingdom; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom. Electronic address: sk24g09@ecs.soton.ac.uk.
authors.forename: Sumit
authors.initials: S
authors.lastname: Kalsi
authors.affiliation: Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, United Kingdom.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Powl
authors.affiliation: Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, United Kingdom.
authors.forename: B A
authors.initials: BA
authors.lastname: Wallace
authors.affiliation: Electronics and Computer Science, University of Southampton, Southampton, United Kingdom; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Hywel
authors.initials: H
authors.lastname: Morgan
authors.affiliation: Electronics and Computer Science, University of Southampton, Southampton, United Kingdom; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom. Electronic address: mdp@ecs.soton.ac.uk.
authors.forename: Maurits R R
authors.initials: MR
authors.lastname: de Planque
mesh_terms: D000408:Alamethicin / Q000737:chemistry; D001426:Bacterial Proteins / Q000378:metabolism; D025802:Electric Capacitance; D004852:Epoxy Compounds / Q000737:chemistry*; D005453:Fluorescence; D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D008561:Membrane Fusion; D008855:Microscopy, Electron, Scanning; D010713:Phosphatidylcholines / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry; D015221:Potassium Channels / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004852:Epoxy Compounds; D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D015221:Potassium Channels; C107790:prokaryotic potassium channel; D000408:Alamethicin; C060037:1-palmitoyl-2-oleoylglycero-3-phosphoglycerol; C017251:1,2-oleoylphosphatidylcholine
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