Liquid Phase Electron Microscopy and Spectroscopy of Biological Specimens

Cryo-EM’s greatest strength is the ability to achieve near-atomic level resolutions in native environments of frozen-hydrated biomolecules and cells. However, frozen samples by their very nature reduce very dynamic processes to single snapshots in time. Computational and theoretical inferences enable these snapshots to glimpse the dynamic intermolecular relationships which composes the protein structural ensemble. However, these are “best guesses”regarding the series and direction of conformational changes a given protein makes, often skewed by more stable conformations. Transitioning from single snapshots in time to movies of actual dynamics would transform how we approach protein-drug interactions, studies of protein complex formation in cells, protein aggregation, cell response/interactions and numerous other biologically and clinically relevant phenomena. The rapidly emerging field of liquid phase electron microscopy (LPEM) may be vital to unlocking the next frontier of structural biology in EM – in situ structural dynamics.

Here at the Rosalind Franklin Institute, we are testing ways to encapsulate biological specimens in new graphene and conventional silicon nitride liquid cells to protect them from the harsh vacuum of the electron microscope. This work will allow us to image life in liquid, expanding our understanding across spatial and temporal dimensions. Combined with advanced electron spectroscopic techniques we can start to build a more complete picture of the complex chemical and biological changes which occur within the cell at nanometre resolutions and millisecond timescales.