High-throughput Small Angle X-ray Scattering from proteins in solution using a microfluidic front-end

This manuscript presents, for the first time, the method of automated structural analysis of biomolecules in solution on a microfluidic chip. A polymer-based micrototal analysis system for high-throughput Small-Angle X-ray Scattering (SAXS) data collection from biological macromolecules has been developed. The bioXTAS chip features an integrated X-ray transparent 200 nL sample chamber and diffusion-based mixing of protein and buffer solutions. Software for fully automated fluidic control, data acquisition, and data analysis has been developed. The proof-of concept is based on data using bovine serum albumin as the model system. It confirms the quality of SAXS data generated from small sample volumes and furthermore validates the on-chip mixing capabilities. SAXS data on the gradual unfolding of BSA induced by an anionic surfactant exemplifies how the bioXTAS chip can be used to follow and identify structural changes and proves the feasibility of high-throughput structural analysis in solution. In total, this shows that the bioXTAS chip has the potential for becoming a powerful tool for automated high-throughput structural analysis of macromolecular systems.