Understanding and engineering microstructure-rheology relationships of proteins and designer biomolecules in solution is often hindered by large material requirements to measure a range of properties including protein size and aggregation state, protein-protein interactions, and solution viscosities using a battery of conventional characterization methods. By contrast, recent studies have demonstrated how differential dynamic microscopy (DDM) can be applied to high-speed video microscopy to resolve protein structure and dynamics in solution without the need for molecular labels or high-resolution imaging. Here, we show how protein DDM can be extended to characterize a range of different solution properties, including protein size, hydrodynamic interactions, second virial coefficients and solution viscosities all from a single series of microliter-scale samples. We apply of the protein DDM to understand the self-assembly and rheology of globular, shape-specific and intrinsically disordered proteins, demonstrating its generality for characterizing a wide range of protein structures and behavior. Ultimately, we show how protein DDM can be used to test and refine colloidal theories for protein solution rheology by measuring parameters on “both sides” of these relationships at the same time. The results show promise for developing intensified, high-throughput measurements of scarce biomolecular materials to aid discovery and design of protein formulations for a diverse range of applications.
