Supported lipid bilayers for molecular interaction studies by SPR

A.DAZA-MILLONE; M. ELENA VELA; V. HERLAX; S.MATÉ

Congreso; XLII Reunión Anual de SAB; 2014

Lipid vesicles can adsorb and become planar bilayers from solution onto hydrophilic surfaces like mica and silica [1]. Supported lipid bilayers (SLBs) are suitable as model cellular membranes for biophysical studies and medical applications. Nevertheless, there is a technological challenge: to be able to succeed preparing SLBs the influence of variables such surface modification, lipid composition of vesicles and buffer composition must be separately studied [2]. SPR (surface plasmon resonance) is a technique that allows following molecular interactions in real time through changes in the media surrounding a thin gold film without need of labeling the lipids [3]. In this work, we prepared small unilamelar vesicles (SUVs) with single composition (DMPC, POPC, DPPC and DOPC) and ternary composition (DOPC/16:0 SM/Cho and DOPC/24:1/Cho) to attempt fusion at a constant temperature (23 °C). The thin gold surfaces were modified with self-assembled monolayers (SAMs) of two different alkanethiols (dithiothreitol, DTT and mercaptoundecanol, MUOH). Buffer composition PBS or Tris was assayed with or without Ca2+ 1mM. According to the lipid composition, conditions to immobilize vesicles or allow fusion was optimized. In general, DTT SAMs allow higher number of immobilized vesicles and Ca2+ was required to induce fusion. MUOH SAMs allows direct fusion but the adhesion is poorer than to DTT SAMs.