Abstract
This work presents a micro osmotic screening system that grows protein crystals in hours with microgram samples. In each crystallization cell, water is driven in or out of a protein solution (across a semi-permeable membrane) to adjust its concentrations. Employing the bi-directional flow control realized by osmosis, each protein sample can be screened for crystallization conditions over highly extended ranges. In the prototype demonstration, 6 x 8 arrays with an overall size of 20 x 24 x 2.5 mm3 are fabricated and tested in the crystallization experiments. Crystallization conditions for lysozyme, catalase, thaumatin, and xylanase are identified within 1 to 3 hours while consuming less than 20 μl of protein solution each. Furthermore, it is also demonstrated that diffraction-quality crystals may be grown and harvested from the prototype systems. As such, this osmotic system pioneers a new class of rapid screening schemes for high-through- put protein crystallization.