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Instruct PartnerTopic: Correlated cryo-EM and cryo-FIB-SIMS enables spatial and chemical imaging of biological specimens with Hannah Ochner
Time: Thursday July 24th, 2025, 05:00 EST / 10:00 WEST / 11:00 (Belgium) CEST / 12:00 IDT (Israel) / 14:30 IST (India) / 17:00 (SGT) / 18:00 JST / 19:00 AEST / 20:00 AEDT
Electron cryomicroscopy (cryo-EM) provides high-resolution images detailing the
spatial structure of biological samples [1], however, there is no direct way of inferring the chemical composition of objects observed in an electron micrograph. As such information is highly relevant for the identification and localization of specific components within cells, a correlative approach providing both chemical and spatial information is needed [2].
To integrate spatial and chemical analysis into a single workflow at cryogenic temperatures, we combine spatial imaging by cryo-EM with focused ion beam (FIB) milling and chemical imaging by time-of-flight secondary ion mass spectrometry (ToF-SIMS) of the ions created during the FIB milling process [3].
Using bacterial cells as a test system, we were able to correlate and overlay cryo-EM and FIB-SIMS data, showing that the technique allows the mapping of elemental and small-molecule ions within a cellular sample prepared in a near-native state by vitrification. Specifically, we could show that the method can be used to study the uptake of fluorinated drugs and environmental contaminants by bacterial cells. To target larger molecules of biological interest, such as specific proteins, we are employing metal-based labelling strategies of cellular macromolecules to aid localisation in SIMS imaging.
As the technique provides access to the three-dimensional sample volume and is widely applicable to a variety of samples, ranging from single cells to tissue-like samples such as FIB-milled lamellae, it is a promising approach for studying the spatial and chemical properties of biological specimens within an integrated workflow.
[1] Nogales, E. & Mahamid, J. (2024) Nature, 628: 47-56.
[2] Ochner, H. & Bharat, T.A.M. (2023), Structure, 31: 1297-1305.
[3] Pillatsch, L. et al. (2019), Progress in Crystal Growth and Characterization of Materials 65: 1–19.
https://zoom.us/j/96253367585?pwd=etpy1LEpkFU0h2fueZAlG31QjpSQSz.1
Meeting ID: 962 5336 7585
Passcode: 491148
