[123] Cluster-mediated stop-and-go crystallization

Impurities control the formation of bio-crystals and can fully paralyze crystal growth at low levels of supersat­ uration. Traditional impurity models predict that an escape from this so-called “dead zone” requires an increase in the driving force (i.e. supersaturation). In this work, using protein crystals as a model system, we uncover an alternative escape route from the dead zone that does not involve an increase in supersaturation. We demonstrate that the merger of a protein cluster with the crystal surface triggers the formation of an ordered multi-layered island. The newly created surface on top of the resulting 3D island is initially devoid of impurities and there­ fore characterized by near-pure step growth kinetics. The accelerated step advancement on this relatively un­ contaminated surface limits the available time for impurities to adsorb on the emerging terraces and by extension their resulting surface density. Cluster-mediated crystal growth occurring in heterogeneous media can therefore lead to stop-and-go dynamics, which offers a new model to explain crystallization taking place under biological control (e.g. biomineralization).

Recommended citation: A.E.S. Van Driessche, J. Lutsko, D. Maes, M. Sleutel"Cluster-mediated stop-and-go crystallization", J. Crystal Growth, 903, 127024(2022); doi:10.1016/j.jcrysgro.2022.127024
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