Frustrated Self-Assembly – FruSA

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. Here we consider the opposite limit of very complex, ill-fitting particles, whose aggregation generates geometrical frustration. To escape this frustration, our early theoretical results suggest that they tend to form fibrous aggregates. 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 will investigate the effects of geometrical frustration on self-assembly, and establish how universal dimensional reduction actually is. We will thus develop new theoretical methods to tackle complex particles in elasticity and statistical mechanics, as well as experimentally probe colloidal and protein self-assembly using high-resolution 3D printing and X-ray scattering.

Our work will reveal new organizational principles for matter, possibly as broadly applicable as the very concept of crystallization. Beyond providing a deeper understanding of biology and disease, these principles could provide guidelines for engineering objects at the nano- and microscale and lead to a better mastery of processes involved in drug manufacturing and protein crystallography.