Short talk:
Arctic TREx – Combining Cryofixation with Ten-fold Robust Expansion Microscopy to Image Neural Cells

Max Halupczok1, Irmgard Dietzel2, Annika Haak1

1Nanoscopy Group, RUBION, Ruhr-Universität Bochum, N-Süd OG/26 , Bochum, Germany,
2Electrobiochemistry Group, Department of Biochemistry II, Ruhr-Universität Bochum, NC7/174, Bochum, Germany

When preparing biological samples for microscopy, chemical fixation with aldehydes is one of the most common approaches. However, aldehyde treatment can drastically change cytoskeletal morphology, damage membrane integrity, or hinder epitope accessibility. Thus, it is advisable to switch from chemical fixation to cryofixation whenever possible as cryofixation has been shown to better preserve the native sample structure[1]. This year, Laporte et al have published a method to combine cryofixation and 4x expansion microscopy (Cryo-ExM)[2] thereby supplying an easy to follow protocol implementing cryofixation into super-resolution fluorescence imaging. Unlike other super-resolution techniques, expansion microscopy (ExM)[3] works with a common widefield fluorescence microscope to achieve resolutions below the diffraction limit. Instead of relying on optical advances or statistical calculations, the sample itself is physically expanded by anchoring it to an expandable hydrogel. Here, we further extended the protocol of Laporte et al by combining it with Ten-fold Robust Expansion Microscopy (TREx)[4]. Using this new technique, which we call arctic TREx, we imaged the subcellular structures of primary neural cells from postnatal rats achieving resolutions below 100 nm.

[1] Neuhaus et al, Journal of Structural Biology 1998, 121, 326–342.
[2] Laporte et al, Nature Methods 2022, 19, 216–222.
[3] Chen et al, Science 2015, 347, 543–548.
[4] Damstra et al, eLife 2022, 11.

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