New crystallization systems envisioned for microgravity studies

Laboratory-based systems have been constructed to demonstrate two methods which will allow for dynamic control of protein-crystal growth. The technologies developed in these systems will be incorporated into future flight hardware for use in microgravity studies. The first method uses a precisely controlled vapor-diffusion approach to monitor and control protein-crystal growth. This approach utilizes a humidity sensor and various interfaces under computer control to effect virtually any evaporation rate from up to 40 different growth solutions simultaneously. A static laser-light-scattering sensor can be used to detect aggregation events and trigger a change in the evaporation rate for a growth solution. The second method exploits the varying solubility of proteins versus temperature to control the growth of protein crystals. This approach utilizes miniature thermo-electric devices under microcomputer control which change temperature as needed to grow crystals of a given protein. Complex temperature ramps are possible using this approach. A static laser-light-scattering probe is also included in this system as a noninvasive probe for detection of aggregation events. The systems constructed demonstrate significant advances in the ability of researchers to gain control of the protein-crystal growth process and will provide tremendous opportunities for microgravity research.