Soiree

Fluid membranes as unique biomaterials

Bortolo Mognetti - Université Libre de Bruxelles, Brussels, Belgium

Robert Vacha - Masaryk University, Czech Republic

Thursday 15th November 2018
Time: 4pm
Venue: Ramsay Lecture Theatre, Christopher Ingold Building, UCL Dept. of Chemistry, Gordon Street
Contact: Karen Stoneham
Tel: 0207 679 7306

Bortolo Mognetti - Université Libre de Bruxelles, Brussels, Belgium

Interdisciplinary Center for Nonlinear Phenomena and Complex Systems


Abstract

Ligand-receptor interactions are pivotal in biology where they are used, for instance, to regulate adhesion between lipid bilayers or to enable responsiveness to environmental stimuli. Biomimetic systems can replicate the functionalities of biological materials through the use of supramolecular ligand-receptor complexes to direct interactions between unit components.

We will present a multiscale strategy allowing to model ligand-mediated interactions in systems with many particles eventually interacting with functionalized interfaces. We will highlight how often aggregation is strongly affected by the timescales at which ligand-receptor linkages form and break. Surprisingly, finite reaction rates drastically hamper relaxation towards equilibrium configurations resulting in more open aggregates when studying self-assembly, or fewer bound particles when studying targeting.

We will then employ our framework to design a system in which functionalized interfaces initialise a cascade reaction leading to self-assembly of colloidal crystals with finite thickness. Specifically, we will consider colloidal supported lipid bilayers functionalized by two types of complementary DNA sticky-ends. In bulk, intra-particle linkages prevent colloidal aggregation. In our system, the functionalized interface destabilises intra-particle linkages and initiates self-assembly by magnifying particle-particle interaction. Importantly, our design provides full control over the crystal thickness.

 

Biography

After completing his studies in Milan (Italy), Bortolo Matteo Mognetti held post-doctoral positions in Mainz (Germany), Oxford (United Kingdom), and Cambridge (United Kingdom) working in the field of computational and theoretical soft matter. In October 2013 he was appointed lecturer (chargé de cours) at the Université Libre de Bruxelles (ULB, Belgium). He is currently interested in studying programmable self-assembly. Recently, he has been awarded an A.R.C. (ULB) grant from Fédération Wallonie-Bruxelles and an M.I.S. grant from F.R.S.-FNRS.


Robert Vacha - Masaryk University, Czech Republic

Interaction of proteins and protein aggregates with phosholipid membranes

 

Abstract

Interaction of proteins and their aggregates with phospholipid membranes is crucial in many biological processes. We will focus on processes that compromise the membrane barrier function and allow the proteins or nanoparticles to pass through the membrane. The discussed examples are virus capsids that undergo endocytosis and proteins that can spontaneously translocate the cell membrane. Using computer simulations with coarse-grained models, we found that the homogeneous distribution of binding sites on the capsid/nanoparticle is the most advantageous for cellular uptake. Moreover, this uptake can be prevented by inhibitors, out of which the multivalent inhibitor were the most effective, in particular when half of the inhibitor could bind to the capsid while the other half could not. For translocating proteins, we demonstrated that there is an optimal protein hydrophobicity which enables the proteins to translocate across the membrane without a significant energy barrier. This new molecular-level understanding is expected to be useful for the rational design of new peptide therapeutics and molecular cargos.

 

Biography

Robert Vácha received his Ph.D. from Charles University, Prague in 2009 working with Pavel Jungwirth on the adsorption and behavior of atmospherically and biologically relevant molecules and ions at the air/water and water/membrane interface. During the studies, RV was also successfully enrolled in the International Max Planck Research School for in Dresden. For his first postdoctoral position, he joined the group of Daan Frenkel at the University of Cambridge, where RV studied phospholipid membrane and protein interactions using coarse-grained models and obtained the prestigious Junior Research Fellowship at Churchill College. His second postdoc was in 2011 with Mikael Lund at Lund University, where he studied amyloid growth and its influence by surfaces. Then, Robert Vácha returned to the Czech Republic as an assistant professor at CEITEC Masaryk University, where he investigates protein-protein and protein-membrane interactions. He is the author of 46 reviewed articles including publications in PNAS, Nano Letters, ACS Nano, JACS, Accounts of Chemical Research. His current H-index is 28 with over 2500 citations.

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