Multichannel femtoliter sample handlerfor targeted cryo-EM sample preparation
(in collaboration with Urs Staufer TU Delft and Bram Koster, University of Leiden).
Because most cells are much larger than the mean-free path of electrons, transmission EM requires such samples to be sliced into thin sections. The ultimate structural preservation of any biological matter is achieved by rapid freezing, which vitrifies water. To vitrify cell or even tissue, rapid freezing must be done under high pressure. Sectioning then is executed at low temperature to prevent crystallization of vitrified water.
Although this can now be accomplished, a more direct preparation method will be developed, taking advantage of hollow cantilevers implemented in an atomic force microscope (AFM). The cantilever will be combined with an integrated micro pump that can aspire or release femto to pico L fluid volumes through an aperture in the cantilever tip. The AFM will be on an inverted phase-contrast/fluorescent microscope, allowing cells and subcellular structures to be identified, addressed by the tip, aspired and subsequently deposited on an EM grid for vitrification. This general, novel sample preparation method will be of great use in many projects of the BioNano Department.