Simposio: Nanomechanical properties and molecular recognition assessed by Force Spectroscopy

MATÉ, SABINA M.; VAZQUEZ, ROMINA F.; DAZA MILLONE, MARÍA A.; VELA, MARÍA E.

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Biofísica.; 2018

Nanomechanical properties and molecular recognition assessed by Force SpectroscopyDaza Millone MA, Vázquez R, Maté S, Vela METhe characterization of biological membranes involves many issues, from their composition at the molecular level to their morphological and structural aspects. The use of model biomembranes has allowed numerous advances in the study of interactions with molecules, the identification of phases and in the quantification of their nanomechanical properties. The Atomic Force Microscopy (AFM) has turned out to be one of the most powerful techniques in the investigation of these subjects and in particular the Force Spectroscopy (FS) offers valuable information in the nanometric scale allowing to monitor processes in physiological medium and in real time. In this work, we present results from Surface Plasmon Resonance (SPR) and AFM of a ternary lipid mixture (DOPC/ 16:0-SM/Cho) that 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. This ternary lipid mixture mimics lipid raft-like domains. Supported lipid bilayers (SLBs) were formed by vesicle fusion either on mica or on dithiothreitol (DTT) self-assembled monolayers on Au following previous procedures. The presence of different lipid phases was characterized by topographic AFM images on mica substrates and by FS on mica and Au/DTT surfaces. FS gives information about the nanomechanical properties and distribution of lipid phases in SLBs and is used in this work to confirm the lipid bilayer formation on a non-flat surface like polycrystalline Au. The nanomechanical properties of SLBs formed on polycrystalline Au were comparable to the ones obtained on a flat mica substrate. The combination of these techniques corroborates the adequate formation of SLBs on Au chips opening a great variety of studies concerning interactions of model biomembranes with biomolecules, surfactants and nanomaterials among other systems by SPR.