Carbon nanotubes as the supporting film for cryo-EM specimen preparation.

Specimen preparation is a critical and rate-limiting step in cryo-EM structural analysis, primarily due to challenges posed by the air-water interface. In this study, we introduce carbon nanotubes (CNTs) as a one-dimensional fibrous support material to address this issue. CNTs interact with macromolecules, effectively protecting them from air-water interfaces, and macromolecules arrange themselves around CNTs in various orientations. Furthermore, CNTs biofunctionalized with affinity tags exhibit strong specificity in binding target macromolecules, facilitating direct purification of targets from cell lysates and on-grid assembly of complexes for subsequent cryo-EM analysis. We also demonstrate that CNT grids are compatible with cell culturing, allowing for seamless integration into the cryo-EM characterization workflow for cellular structures. We anticipate that these properties will make the CNT network a promising support for cryo-EM.