Phase-segregated Membrane Model assessed by a combined SPR-AFM Approach

Publication year: 2018
Authors: Millone D.A.M. 1, Vázquez R.F. 1, Maté S.M. 2, Vela M.E. 3
Affiliations:

1 - Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT- La Plata, CONICET, Universidad Nacional de La Plata, Sucursal 4 Casilla de Correo 16, La Plata, 1900, Argentina
2 - Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CCT- La Plata, CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, La Plata, 1900, Argentina
3 - Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT- La Plata, CONICET, Universidad Nacional de La Plata, Sucursal 4 Casilla de Correo 16, La Plata, 1900, Argentina

Published in: Colloids and Surfaces B: Biointerfaces, 2018, Vol. 172, p. 423-429
doi: 10.1016/j.colsurfb.2018.08.066

Model biomembranes can provide valuable insights into the properties of complex biological membranes. Among several techniques, Surface Plasmon Resonance (SPR) provides a label-free analysis of the interactions of bioactive molecules with biomembranes with an experimental setup that allows mimicking biological environments. Nevertheless, protocols that enable the preparation of stable supported membrane systems with reproducible structural and functional properties on the biosensor chip are still needed. In this work, we present a simple protocol to modify SPR substrates that allows the formation of a phase-segregated supported lipid bilayer (SLB). SLBs are formed by fusion of lipid vesicles of pure phospholipids (DMPC, DPPC and DOPC) and of a ternary mixture (DOPC/16:0 SM/Cho in 2:1:1 molar ratio) on a SPR gold sensor chip covered with a dithiothreitol monolayer. The formation of a SLB on the SPR sensing surface in a reproducible way was assessed by the combined use of the SPR technique with AFM. The interaction of a cholesterol-extracting drug with SLBs was studied as a model of membrane-lipophilic biomolecule interaction. The proposed strategy allowed us to obtain a membrane model where phase coexistence is present and where Cho depletion from ternary mixtures was comparable to the extraction results reported for human erythrocytes.


MP-SPR keywords: AFM, cholesterol depletion, cholesterol-extracting drug, density, drug lipid interaction, kinetics, lipid bilayers, membrane, supported lipid bilayer