Instrument: OptiCrys/MicroCrys

Contact: Monika Spano

The so-called crystallization bench (OptiCrys) is a prototype of an integrated apparatus for the rational optimization of crystal growth by mapping and manipulating temperature–precipitant–concentration phase diagrams. It comprises a flow cell dialysis set-up (typical volume >20 μL) to exchange conditions and control temperature during the experiments. Based on this macro scale instrument, a miniaturized device that allows precise control of the experimental parameters exploiting the advantages of microfluidics such as the control of transport phenomena and the reduced sample volume needed per experiment (typical volume <1 μL) is also available (MicroCrys). The novelty is the use of the dialysis method on a unique versatile microfluidic device, designed to meet the requirements of both on-chip protein crystallization and in situ X-ray serial crystallography. Precipitant concentration is controlled via both platforms (OptiCrys/MicroCrys) for fluid handling and an interactive software interface designed for the preparation of the crystallization solution. Salts, solvents, buffers and other solutions can be premixed and are then pumped into the (macro/micro) fluidic system in a fully automated way. Temperature is controlled within the (macro/micro)fluidic devices via a prototype using external heating through Peltier modules and copper elements. Therefore, both, the homogeneous temperature distribution or temperature gradients, are achieved. Physico-chemical parameters such as temperature, concentration of crystallizing agents and pH can be controlled over time during the crystallization, so that the state of the substance studied moves along a well defined kinetic trajectory in the phase diagram. The dialysis membrane allows for adjusting the mass transfer through the membrane during the crystallization process. As a result, the gradients created can be controlled and affect the size and quality of generated crystals.

Relevant publications:

A microfluidic device for both on-chip dialysis protein crystallization and in situ X-ray diffraction. Junius N, Jaho S, Sallaz-Damaz Y, Borel F, Salmon J-B, Budayova-Spano M (2020) Lab Chip 20, 296-310.

A crystallization apparatus for temperature-controlled flow-cell dialysis with real-time visualization. Junius N, Oksanen E, Terrien M, Berzin C, Ferrer J-L, Budayova-Spano M (2016) J. Appl. Crystallogr. 49, 806-813.