  Controlling the self-assembly of supramolecular structures is vital for
living cells, and a central challenge for engineering at the nano- and
microscales. Nevertheless, even particles without optimized shapes can robustly
form well-defined morphologies. This is the case in numerous medical conditions
where normally soluble proteins aggregate into fibers. Beyond the diversity of
molecular mechanisms involved, we propose that fibers generically arise from
the aggregation of irregular particles with short-range interactions. Using a
minimal model of ill-fitting, sticky particles, we demonstrate robust fiber
formation for a variety of particle shapes and aggregation conditions.
Geometrical frustration plays a crucial role in this process, and accounts for
the range of parameters in which fibers form as well as for their metastable
character.
