INVESTIGADORES
DAZA MILLONE Maria Antonieta
congresos y reuniones científicas
Título:
Self-healing properties of supported DMPC bilayers on dithiothreitol SAMs
Autor/es:
MARÍA ANTONIETA DAZA MILLONE; MAXIMILIANO LUIS MUNFORD; TÂNIA BEATRIZ CRECZYNSKI-PASA; ANDRÉ AVELINO PASA; MARÍA ELENA VELA; ROBERTO C. SALVAREZZA
Lugar:
San Carlos de Bariloche (Pcia. Río Negro)
Reunión:
Workshop; US-Argentina Workshop on Nanomaterials; 2009
Resumen:
Supported lipid bilayers on solid substrata have attracted considerable interest, both from the fundamental (structure and properties) and applied (biosensing and biofunctionalization) points of view. We prepared dimyristoilphosphatidilcholine (DMPC) unilamellar vesicles and allow them to fuse on a dithiothreitol (DTT) self-assembled monolayer (SAM). DTT assembles on gold in a way that a hydrophilic surface is reached allowing vesicle fusion. We use AFM in situ measurements to evaluate the coverage of these bilayers in an aqueous environment and to perturb it in a controlled way to see its response. Gold ArrandeeTM substrates with or without 3min of annealing with H2 flame were employed. This procedure turns the inicial granulated surface (grain size ~30nm) in mostly flat (111) terraces. DMPC bilayers adapt in a continuous way along grains and terraces but flame annealing leaves deep boundaries where bilayers are interrupted. We prepared a smaller grain (~20nm) sized gold substrate evaporating Au 99,999% in Si(111). We maked a lithographic square window at 18 ⁰C and, while heating the system, we measure DMPC spreading with time. Taking a front displacement L for the time interval ∆t and using L2 = 2D∆t we obtained D = 10^-11 cm^2 s^-1 at 22,5 ⁰C. This value is lower than that reported for DMPC bilayers supported on glass (2 x 10^-10 cm^2 s^-1 at 22,5 ⁰C ). The discrepancy can be explained either by a self-limiting spreading or by an increased interaction of DMPC with the underlying DTT/Au with respect to the glass substrate. The DMPC lateral motion points toward the maintenance of membrane dynamics, a signal that this system could be adequate for fundamental studies in general phenomena of natural membranes.