EXTERNAL SEMINAR - Martin Lenz (LPTMS Paris Saclay)

Martin Lenz (LPTMS Paris Saclay) will give a short internal seminar, hosted by Pierre Ronceray (CiNAM).

This seminar will take place in the Hexagone Auditorium.
CENTURI is also providing for off-campus participants only a zoom link to attend the seminar: https://us02web.zoom.us/j/85941690095?pwd=Nm5NVGhESGlUbG1FMnZ2dU5vSlkxUT09

Meeting ID: 859 4169 0095
Secret Code: 002024

Title: Slimming down through frustration

Abstract:

Self-assembly is key to living cells, where it brings well-adjusted

parts together into functional biological structures. In rarer,

pathological cases, ill-fitting proteins also aggregate and form fibers

involved in Alzheimer’s and other diseases. While functional

self-assembly is widely studied, the physical principles governing

ill-fitting self-assembly remain largely unknown.

 

 

Our current understanding of self-assembly revolves around examples

involving simple, relatively symmetrical particles. We instead strive to

consider the opposite limit of very complex, ill-fitting particles,

whose aggregation generates geometrical frustration. To escape this

frustration, our early theoretical and experimental results suggest that

they tend to form fibrous aggregates reminiscent of those formed by

proteins in disease. According to this putative “dimensional reduction”

principle, collections of complex particles generically behave

differently than collections of simple ones. Indeed, while increasing

the attractive interactions in the latter typically induces a transition

from a dilute (gas-like) phase to a dense (liquid or solid) phase, we

propose that the former should generically present an additional,

intermediate regime where fibers (or planes) form.

 

 

We use theoretical tools based on elasticity theory and statistical

mechanics to investigate the effects of geometrical frustration on

self-assembly to establish how widespread universal dimensional

reduction actually is. Our framework opens the way for ongoing

experiments where we probe colloidal and protein self-assembly using

high-resolution 3D printing and X-ray scattering.

 

 

Our work reveal new organizational principles for matter, possibly as

broadly applicable as the very concept of crystallization. This

fundamental advance in our understanding of complex, protein-like object

could have implications for our understanding of biology and disease,

and may also provide guidelines for engineering objects at the nano- and

microscale, as well as lead to a better mastery of processes involved in

drug manufacturing and protein crystallography.