The ability to measure the size and shape of objects is something we take for granted at the macroscale. High precision methods for determining size and shape at the molecular level provide insight that are vital to biology. What's more, the ability to do so in physiological conditions with a high throughput is incredibly sought after. Escape-Time stereometry (ETs) is a high throughput single molecule technique, that can unlock understanding into how biomolecules bend, fold and cluster in native biological settings. Building on the groups work on Escape-Time electrometry (ETe), ETs moves to biologically meaningful buffer conditions where the decreased range of these electrostatic forces causes entropic effects that rely on the structure of the molecule, to dominate over charge. This permits size and shape information to be extracted from the measurement rather than effective charge.
ETs is conducted in nanoslits containing small divots or pockets, that are considerably deeper than the slits themselves. The thin channels constrain the vertical movements of the molecules, while the pockets offer more vertical space and act as entropic 'traps'. Larger molecules remain in these regions for longer and the time taken for the molecules to escape these traps can inform us on the distribution of shapes and sizes present (stereometry). Using widefield fluorescent microscopy, molecules can be tracked in real time and structural changes can be observed live. Such conformational changes of biological molecules, e.g., those triggered in the insulin receptor upon ligand binding, could even provide valuable diagnostic approaches. ETs further permits probing of weak molecular interactions such as clustering of biomolecules which play crucial roles in biological function and are even implicated in neurological diseases . A deeper understanding of the underlying thermodynamics and kinetics of these interactions could lead to new insights into disease mechanisms and potential therapeutic strategies.
