Cryo-EM structures from sub-nl volumes using pin-printing and jet vitrification
![](https://cryosol-world.com/wp-content/uploads/2022/04/Cryo-EM-structures-from-sub-nl-volumes-using-pin-printing-and-jet-vitrification.jpg)
Raimond B. G. Ravelli; Frank J. T. Nijpels; Rene J. M. Henderikx; Giulia Weissenberger; Sanne Thewessem; Abril Gijsbers; Bart W. A. M. M. Beulen; Carmen López-Iglesias; Peter J. Peters
The increasing demand for cryo-electron microscopy (cryo-EM) reveals drawbacks in current sample preparation protocols, such as sample waste and lack of reproducibility. Here, we present several technical developments that provide efficient sample preparation for cryo-EM studies. Pin printing substantially reduces sample waste by depositing only a sub-nanoliter volume of sample on the carrier surface. Sample evaporation is mitigated by dewpoint control feedback loops. The deposited sample is vitrified by jets of cryogen followed by submersion into a cryogen bath. Because the cryogen jets cool the sample from the center, premounted autogrids can be used and loaded directly into automated cryo-EMs. We integrated these steps into a single device, named VitroJet. The device’s performance was validated by resolving four standard proteins (apoferritin, GroEL, worm hemoglobin, beta-galactosidase) to ~3 Å resolution using a 200-kV electron microscope. The VitroJet offers a promising solution for improved automated sample preparation in cryo-EM studies.