Electron Microscopy Project

Our unit has been working on developing a new biospecimen preparation system for EM based on electrospraying (ES) technology. We have long been focusing on such application of ES since it can potentially be used to generate desolvated “naked” biomolecules, which is logically the most ideal form for specimens to be imaged by TEM/STEM at low voltages. However, this kind of application of ES is not common as it is only applicable to those samples that can meet very specific and stand with rather harsh conditions. For this reason, ES has rarely been applied to large biological macromolecules and, as a result, how well biomolecular structures may be preserved after the solvent removal by ES is still not well understood. To address this problem and explore the potential of ES for EM specimen preparation, we have built experimental devices.  Although challenging, we believe that the realization of this technique should greatly contribute to a field of single (bio)molecular imaging. Further development is underway.

Based on a new type of electron microscope theory developed by Professor Shintake in 2021, a unique ring slit was incorporated into the JEOL CRYO ARM300 at the Namba Laboratory of Osaka University in 2022. Imaging using this system eliminates the spherical aberration of the focusing lens in the electron microscope, making it possible to capture molecules inside crystals that have been difficult to observe directly in high resolution. In particular, it is thought that this system will be highly effective in directly visualizing proteins, which are biopolymers, and analyzing crystals of organic-inorganic hybrid materials and drug crystals that are easily affected by electron beam damage.
As a demonstration of this microscope and analysis system, crystallization of multiple samples, imaging with an electron microscope, and analysis by image processing were performed. A model diagram generated from a known crystal structure was superimposed on the electron microscope image, from which noise had been removed using an FFT filter. This is the first time in the world that the structure of a biopolymer crystal has been directly observed at the molecular level using an electron microscope.