Raft-like model membranes for biomolecular interaction studies

ROMINA F. VAZQUEZ; M. ANTONIETA DAZA MILLONE; M. ELENA VELA; SABINA M. MATÉ

La Plata

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Biofísica (SAB); 2018

Sociedad Argentina de Biofísica (SAB)

Biomimetic membrane models are promisingplatforms to complement in vitro cell-screening assays in the analysis ofbiochemical and biophysical interactions. The design and study of theseplatforms is not only important regarding cell biology research but also fromadvanced applications in pharmaceutical industry. In particular, the presenceof segregated domains or ?lipid raft-like domains?, in the membrane interfaceplays a critical role in studies of biomolecular interactions. Among the newtechniques employed for these studies, Surface Plasmon Resonance (SPR) providesa label-free analytical approach that allows high-throughput screening of thestructural and compositional factors that mediate the binding of bioactivemolecules to the membrane. Here, we present results concerning the preparationof a supported lipid bilayer (SLB) on a SPR chip from vesicles of a ternarylipid mixture (DOPC/SM 16:0/Cho, 2:1:1 molar ratio). This mixture waspreviously characterized on mica surfaces and exhibits phase coexistence, i.e.a liquid-ordered (Lo) phase enriched in sphingomyelin (SM) and cholesterol(Cho) which is segregated from the liquiddisordered (Ld) phase composed mainlyof DOPC. We demonstrate that these domains have similar nanomechanicalproperties on DTT-Au surfaces by means of Force spectroscopy (FS). Finally, weevaluate the biomimetic properties of the SLB employing a Cho-extracting drug.The results show that the percentage of Cho release bears close resemblance tothe one reported for erythrocytes and the kinetics of the depletion followed abiexponential model, consistent with two pools of Cho, i.e. the presence of Choin segregated domains.