Supported lipid bilayers for molecular interaction studies by SPR

DAZA MILLONE, M. A.; VELA, M. E.; VANESA HERLAX; SABINA MATÉ

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Biofísica; 2014

Lipid vesicles can adsorb and become planar bilayers from solutiononto hydrophilic surfaces like mica and silica [1]. Supported lipidbilayers (SLBs) are suitable as model cellular membranes forbiophysical studies and medical applications. Nevertheless, thereis a technological challenge: to be able to succeed preparing SLBsthe influence of variables such surface modification, lipidcomposition of vesicles and buffer composition must be separatelystudied [2]. SPR (surface plasmon resonance) is a technique thatallows following molecular interactions in real time throughchanges in the media surrounding a thin gold film without need oflabeling the lipids [3]. In this work, we prepared small unilamelarvesicles (SUVs) with single composition (DMPC, POPC, DPPCand DOPC) and ternary composition (DOPC/16:0 SM/Cho andDOPC/24:1/Cho) to attempt fusion at a constant temperature(23 °C). The thin gold surfaces were modified with self-assembledmonolayers (SAMs) of two different alkanethiols (dithiothreitol, DTTand mercaptoundecanol, MUOH). Buffer composition PBS or Triswas assayed with or without Ca2+ 1mM. According to the lipidcomposition, conditions to immobilize vesicles or allow fusion wasoptimized. In general, DTT SAMs allow higher number ofimmobilized vesicles and Ca2+ was required to induce fusion.MUOH SAMs allows direct fusion but the adhesion is poorer thanto DTT SAMs.1 Richter, R. P., R. Berat, and A. R. Brisson. Langmuir.2006.22:3497?35052 Nollert, P., H. Kiefer, and F. Jähnig. Biophys. J. 1995. 69:1447?1455.3 Morigaki, K and Tawa, K, Vesicle Fusion Studied bySurface Plasmon Resonance and Surface PlasmonFluorescence Spectroscopy. Biophys. J. 2006. 91 1380?1387