Geometrically frustrated self-assembly: what determines the dimensionality of the aggregates?
Pierre Ronceray (Princeton University)
Irregularly shaped particles with attractive interactions, such as proteins or patchy colloids, are in general frustrated: it is impossible to arrange them in space such that all attractive interactions are simultaneously satisfied. In a dense phase, this implies that any configuration must include defects to the favoured local order. In contrast, in a dilute system of self-assembling particles, an interesting alternative exists: defects can be avoided if instead of having a 3D crystalline structure, the aggregate has a reduced dimensionality - 2D sheets, 1D fibers or 0D micelles. Indeed, numerical experiments on simple models for low-symmetry attractive particles reveal a rich variety of morphologies, including all possible dimensionalities, for near-equilibrium low-temperature aggregates. Strikingly, while one-dimensional aggregates are always thermodynamically unstable, they nucleate quickly and can be extremely long-lived. This generic physical mechanism could provide a rationale for the formation of proteins into pathological fibrous aggregates in a variety of diseases, such as Parkinson's and Alzheimer's.
Please contact M.Gradhand@bristol.ac.uk for further information.