CREIM: Coffee Ring Effect Imaging Model for Monitoring Protein Self-Assembly in Situ.

Protein self-assembly is fundamental to nanotechnology. Self-assembling structures are produced under static in vitro conditions typically forming over hours. In contrast, hydrodynamic intracellular environments employ far shorter time scales to compartmentalize highly concentrated protein solutions. Herein, we exploit the radial capillary flow within a drying sessile droplet (the coffee ring effect) to emulate dynamic native environments and monitor an archetypal protein assembly in situ using high-speed super-resolution imaging. We demonstrate that the assembly can be empirically driven to completion within minutes to seconds without apparent changes in supramolecular morphology. The model offers a reliable tool for the diagnosis and engineering of self-assembling systems under nonequilibrium conditions.