Tailoring the interfacial assembly and the mechanical response of colloidal and biological systems

DIPC Seminars

Armando Maestro, Institut Max von Laue - Paul Langevin ILL, France
Online seminar, Donostia International Physics Center
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Tailoring the interfacial assembly and the mechanical response of colloidal and biological systems Fluid interfaces can be used as a platform for promoting the direct and spontaneous self-assembly of colloidal systems, including amphiphilic molecules, macromolecules and organic and metallic nanoparticles, where the driving force is the reduction in interfacial energy. Besides, fluid interfaces allow fine-tuning of the ensemble of molecules by an external force, such as the presence of an imposed interfacial flow, or by engineering the molecular interactions dictated by the interplay of interfacial forces. As a consequence, a wide-ranging set of interfacial structures can be achieved: from liquid-like layers, which can flow under stress, to amorphous solids that can sustain static stress [1]. In this talk, I will first discuss different ways of quantitatively tuning and tailoring the mechanical response and the interfacial assembly of colloidal systems confined at fluid interfaces. In particular, I will focus on the link between the structure, measured by neutron reflectivity and ellipsometry, and the mechanical properties (employing different shear probes) of different versatile systems that we have studied lately: Ligand-coated spherical silica nanoparticles, synthetic soft microgel particles (based on chemically cross- linked acrylamide polymers), graphene oxide sheets, and very recently surfactant/polyelectrolyte mixtures and lipid nanoparticles. In the second part of the talk, I will report different experimental investigations involving phospholipids and proteins (or peptides) recreating, by in vitro models studied by neutron scattering, relevant biophysical processes happening at biomembrane surfaces. For example, the first stage of endocytosis [2], by studying the composition, structure and mechanics of a complex layer formed by protein/lipids that self-assembles in stages generating membrane curvature. And, very lately the viral fusion mechanism [3]. References [1] A. Maestro, Current Opinion in Colloid and Interface Science, 2019, 39, 232; [2] Kelly BT and Owen DJ, Science, 2014, 345, 459. [3] L. Du et al., Nature, 2009, 7, 226. Host: Juan Colmenero ZOOM: YouTube: