Molecular-scale Structural and Functional Characterization of Sparsely Tethered Bilayer Membranes

Published

October 12, 2021

Author(s)

Duncan McGillivray, Gintaras Valincius, David J. Vanderah, W Febo-Ayala, John T. Woodward IV, F Hienrich, John J. Kasianowicz, M Losche

Abstract

Surface-tethered biomimetic bilayer membranes (tethered lipid bilayer membranes, tBLMs) have been formed on gold surfaces from phospholipids and a synthetic 1-thiahexa(ethy lene oxide) lipid, WC14. They have been characterized using electrochemical impedance spectro scopy (EIS), neutron reflection (NR) and Fourier-transform infrared reflection-absorption spec troscopy (FT-IRRAS) to obtain functional and structural information. Electrically insulating membranes (conductance and capacitance as low as 1 ?Scm-2 and 0.6 ?Fcm-2, respectively) with high surface coverage (>95% completion of the outer leaflet) are formed from a range of lipids, in a simple two-step process that consists of the formation of a self-assembled monolayer (SAM) and bilayer completion by rapid solvent exchange . NR provides a molecularly-resolved charac terization of the interface architecture and, in particular, the constitution of the space between the tBLM and the solid support. In tBLMs based on SAMs of pure WC14, the hexa(ethylene oxide) tether region has low hydration even though FT-IRRAS shows that this region is structurally disordered. However, on mixed SAMs made from the co-adsorption of WC14 with a short-chain backfiller , ?-mercapto ethanol (?ME), the tBLM sub-membrane spaces contain up to 60% exchangeable solvent by volume, as judged from NR and contrast variation of the solvent. Com-plete and stable sparsely-tethered BLMs (stBLMs) are readily prepared from SAMs chemi sorbed from solutions with low WC14 proportions. Phospholipids with unsaturated or saturated, straight or branched chains all form qualitatively similar stBLMs.

Citation

Journal of the American Chemical Society

Pub Type

Journals

Keywords

electrochemical impedance spectroscopy, neutron reflectometry, self-assembled monolayers, tethered bilayer membranes

Citation

McGillivray, D. , Valincius, G. , Vanderah, D. , Febo-Ayala, W. , Woodward IV, J. , Hienrich, F. , Kasianowicz, J. and Losche, M. (2021), Molecular-scale Structural and Functional Characterization of Sparsely Tethered Bilayer Membranes, Journal of the American Chemical Society (Accessed December 26, 2024)