Influence of Shear on Protein Crystallization under Constant Shear Conditions
Sander Stroobants, Manly Callewaert, Marzena Krzek, Sudha Chinnu, Pierre Gelin, Iwona Ziemecka, James F. Lutsko, Wim De Malsche, Dominique Maes
Abstract
A novel microfluidic device that subjects a solution to a constant shear flow was developed. By taking advantage of the linear velocity profile in a lid driven flow configuration, small volumes (10–5 L) can be subjected to a constant shear profile with a shear rate between 0.1 and 100 s–1 at accurately controlled temperatures between 20 and 50 °C. The tunable shear can be maintained for extensive and fully controlled times. A dedicated microscope setup for visualization enables the on-chip detection of micron-sized crystals, particles, and aggregates. The influence of shear on the crystallization process of the reference protein lysozyme was studied. The results indicate that shear rates between 1 and 10 s–1 decrease solubility and promote nucleation not only in the supersaturated and metastable zones of the phase diagram, but also in the undersaturated zone. A monotonically increasing nucleation rate was observed for shear rates between 1 and 10 s–1. It is anticipated that the presented methodology can shed light on a variety of phase transitions that are influenced by flow.