Microfluidic Chip

About

Background: Sixty percent of drugs target an important class of membrane proteins know as G protein-coupled receptors (GPCRs), representing $47 billion in annual sales. However, due to vast difficulties in obtaining high quality and stable protein crystals for X-ray crystallography, only a few of membrane protein structures have been solved. An efficient and automated method for optimizing protein crystallization conditions will be invaluable for developing specific drug targets. A microfluidic chip, which consists of very small fluid channels and small reaction chambers at a high density (1000 microwells per square inch), can be implemented in the protein crystallization optimization process. Microfluidic systems offer many advantages over conventional crystallization techniques and allow automated screening of many sample conditions simultaneously, resulting in faster, cheaper, and reproducible analyses.  Applications: • Phase Chip is designed for the optimization of protein crystallization conditions. • To determine phase diagrams of a wide variety of other multicomponent fluids, such as surfactants, liquid crystals, polymer solutions, drug polymorphs.  Advantages: • Lab-on-a-chip technology allowing high-throughput screening and automation. • Uses 1,000 times less protein than standard crystallography. • Phase Chip can store hundreds of sub-nanoliter drops in individual wells and permits hundreds of crystallization conditions to be tested per chip. • Decouples crystal nucleation and growth in a precisely controlled and reversible way, allowing independent optimization of the two processes to produce high quality and stable crystals for X-ray crystallography. • Prototype has been built and tested successfully. Technology: The Phase Chip is a microfluidic device that allows high throughput screening of protein crystallization conditions. The device is manufactured using soft-lithography, and contains microwells for the storage of microdrops of protein-solvent mixtures. The bottom of a microwell is a semi-permeable membrane separating the storage cell from a reservoir. The water in the microdrop and in the reservoir are in chemical equilibrium via the membrane. By varying the chemical potential of the reservoir, the concentration of solutes in the microdrop can be precisely manipulated and in a reversible way. Because crystallization is a nonequilibrium process it is necessary to screen the duration and length of quenches of the metastable solution into deep supersaturation. The Phase Chip is designed to systematically screen the two parameters of quench time and depth and exploits the benefits of microfluidics, such as low volume, high throughput and ease of automation, to produce faster and less costly analyses. Using the Phase Chip, we can control the nucleation and crystal growing processes independently, allowing optimal conditions for membrane protein crystallization.