A simple pressure-assisted method for MicroED specimen preparation

Micro-crystal electron diffraction (MicroED) is a promising technique for determining the structure of macromolecular crystals too small for X-ray diffraction. However, specimen preparation remains a major bottleneck. This paper introduces Preassis, a simple pressure-assisted method for preparing MicroED specimens. Preassis removes excess liquid through an EM grid using pressure, allowing control of ice thickness by adjusting pressure and grid carbon hole size. It's shown to be effective with various protein crystals and buffer conditions, including high-viscosity samples and low crystal concentrations. Preassis is a universal and simple method that significantly broadens MicroED applications.

Jingjing Zhao, Hongyi Xu, Hugo Lebrette, Marta Carroni, Helena Taberman, Martin Högbom, Xiaodong Zou