Polymer Based Microfluidic Systems for Protein Crystallization & Structure Determination

X-ray crystallography has been the most widely used technique for protein structure determination, providing detailed insight into how these biological macromolecules function. These structural insights have profoundly impacted human life by facilitating breakthroughs in drug discovery, protein engineering, and enhancing our understanding of vital biological mechanisms. However, continuous advancements are essential to enhance crystal quality, develop strategies for identifying optimal crystallization conditions, and optimize sample delivery to current and future generations of X-ray sources, crucial for unlocking the structures of proteins that remain unresolved. Microfluidic technology presents a promising avenue for addressing these challenges and advancing the process of protein structure determination.With the aim of overcoming these bottlenecks, three microfluidic devices were developed including a polymer fixed-target device for precision sample delivery to the X- ray beam, a valve-integrated microfluidic device for high-throughput protein crystallization screening, and a fixed-target device for protein crystallization in microgravity. The fixed-target sample delivery device was meticulously designed to trap crystals in tailored positions, demonstrating high efficiency in crystal trapping. This device was manufactured to be compatible with vacuum experimental chambers of X-ray beamlines and was used to obtain a high resolution structure of the model protein lysozyme. For the screening fixed-target device, valve functionality was integrated by successfully combining an elastomeric layer with the X-ray transparent cyclic olefin copolymer (COC). This device demonstrated the capability to screen protein crystallization conditions which was confirmed through cutting-edge imaging techniques. A fabrication protocol and filling i procedure of the microfluidic device for protein crystallization in microgravity was optimized, and proteins were crystallized at the International Space Station (ISS). Assessment of the devices confirmed that the devices withstood rigorous rocket launch and capsule return conditions. Furthermore, image analysis allowed the comparison of protein crystal formation in microgravity with that in unit gravity (g = 9.8 m/s2). These three microfluidic devices demonstrated the capability to improve different steps of the structure determination process and when combined, they hold the potential to revolutionize the field of protein structure determination with X-ray crystallography.