Raft-like model membranes for biomolecular interaction studies

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

La Plata

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

Sociedad Argentina de Biofísica (SAB)

Biomimetic membrane models are promising platforms to complement in vitro cell-screening assays in the analysis of biochemical and biophysical interactions. The design and study of these platforms is not only important regarding cell biology research but also from advanced applications in pharmaceutical industry. In particular, the presence of segregated domains or lipid raft-like domains, in the membrane interface plays a critical role in studies of biomolecular interactions. Among the new techniques employed for these studies, Surface Plasmon Resonance (SPR) provides a label-free analytical approach that allows high-throughput screening of the structural and compositional factors that mediate the binding of bioactive molecules to the membrane. Here, we present results concerning the preparation of a supported lipid bilayer (SLB) on a SPR chip from vesicles of a ternary lipid mixture (DOPC/SM 16:0/Cho, 2:1:1 molar ratio). This mixture was previously 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 liquid disordered (Ld) phase composed mainly of DOPC. We demonstrate that these domains have similar nanomechanical properties on DTT-Au surfaces by means of Force spectroscopy (FS). Finally, we evaluate the biomimetic properties of the SLB employing a Cho-extracting drug. The results show that the percentage of Cho release bears close resemblance to the one reported for erythrocytes and the kinetics of the depletion followed a biexponential model, consistent with two pools of Cho, i.e. the presence of Cho in segregated domains.