Miniaturized Sample Preparation for Transmission Electron Microscopy

Schmidli, Claudio and Rima, Luca and Arnold, Stefan A. and Stohler, Thomas and Syntychaki, Anastasia and Bieri, Andrej and Albiez, Stefan and Goldie, Kenneth N. and Chami, Mohamed and Stahlberg, Henning and Braun, Thomas. (2018) Miniaturized Sample Preparation for Transmission Electron Microscopy. Journal of Visualized Experiments (137). e57310.

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Official URL: https://edoc.unibas.ch/65447/

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Due to recent technological progress, cryo-electron microscopy (cryo-EM) is rapidly becoming a standard method for the structural analysis of protein complexes to atomic resolution. However, protein isolation techniques and sample preparation methods for EM remain a bottleneck. A relatively small number (100,000 to a few million) of individual protein particles need to be imaged for the high-resolution analysis of proteins by the single particle EM approach, making miniaturized sample handling techniques and microfluidic principles feasible. A miniaturized, paper-blotting-free EM grid preparation method for sample pre-conditioning, EM grid priming and post processing that only consumes nanoliter-volumes of sample is presented. The method uses a dispensing system with sub-nanoliter precision to control liquid uptake and EM grid priming, a platform to control the grid temperature thereby determining the relative humidity above the EM grid, and a pick-and-plunge-mechanism for sample vitrification. For cryo-EM, an EM grid is placed on the temperature-controlled stage and the sample is aspirated into a capillary. The capillary tip is positioned in proximity to the grid surface, the grid is loaded with the sample and excess is re-aspirated into the microcapillary. Subsequently, the sample film is stabilized and slightly thinned by controlled water evaporation regulated by the offset of the platform temperature relative to the dew-point. At a given point the pick-and-plunge mechanism is triggered, rapidly transferring the primed EM grid into liquid ethane for sample vitrification. Alternatively, sample-conditioning methods are available to prepare nanoliter-sized sample volumes for negative stain (NS) EM. The methodologies greatly reduce sample consumption and avoid approaches potentially harmful to proteins, such as the filter paper blotting used in conventional methods. Furthermore, the minuscule amount of sample required allows novel experimental strategies, such as fast sample conditioning, combination with single-cell lysis for "visual proteomics," or "lossless" total sample preparation for quantitative analysis of complex samples.
Faculties and Departments:05 Faculty of Science
05 Faculty of Science > Departement Biozentrum > Services Biozentrum > BioEM Lab (Chami)
05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Structural Biology (Stahlberg)
05 Faculty of Science > Departement Biozentrum > Structural Biology & Biophysics > Structural Biology (Braun)
UniBasel Contributors:Stahlberg, Henning and Chami, Mohamed and Goldie, Kenneth N. and Braun, Thomas
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:06 Oct 2021 10:32
Deposited On:13 Oct 2018 08:01

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