CryoEM grid preparation

Recent advances in cryo-electron microscopy (cryoEM), such as the development of direct detectors, automation and 3D particle reconstruction algorithms, have transformed structural biology by enabling investigators to obtain near atomic resolution structures without the need to grow crystals.  A significant challenge that limits the wider applicability of cryoEM as a structural tool is the preparation of suitable samples in thin (< 100 nm) layers of vitreous ice in the approximately micron-sized holes of a grid substrate.  This arises from the large surface-area-to-volume ratio of the thin aqueous layers prior to freezing of the thin liquid layer in a cryogen.  Biological macromolecules preferentially localize to the air-water interface in the thin liquid layer, giving rise to preferred orientations or, in some cases, denaturing.  A significant development in minimizing this problem has been the introduction of droplet based approaches to depositing samples on grids.  In collaboration with Chen Xu, a cryoEM expert and our cryoEM facility director, we are developing a microfluidic-based approach that has the potential to overcome some of the challenges in current sample grid preparation approaches such as localization to the air-water interface, preferential orientation and degradation.  Additionally, the device has the potential to precisely control the ice layer thickness and readily adapt to time-resolved studies.  Successful development has the potential to significantly widen the biological macromolecules and scientific questions that can be addressed by high-resolution structure determination using cryoEM.  That’s all I can say for now but if you’re interested please contact me.