Designing and Application of a Microfluidic Chip with Continuous Concentration Gradients in the Crystallization of Proteins

The complexity and sensitivity of proteins make their crystallization a significant bottleneck in structural biology, materials science, and biopharmaceutical research. The development of microfluidics technology provides substantial advantages in studying protein crystallization, thanks to its low reagent consumption and high-throughput capabilities. In this study, a novel microfluidic chip was designed to enable continuous and precise control of concentration gradients in microdroplets. The structure of the microfluidic chip was designed by using COMSOL in the first place. The accuracy and continuity of droplet concentrations were further confirmed through fluorescence dye experiments. The designed microfluidic chip was then employed to high throughput map the crystallization phase diagram of the model protein lysozyme, demonstrating highly consistent results with 96-well plates. Additionally, a microarray was utilized to effectively screen the crystallization conditions of papain, resulting in the purification of papain through scale-up experiments.