Orateur : Niels de Jonge (Bruker AXS, Karlsruhe, Germany.)

Résumé : Liquid phase electron microscopy (LP-EM) is capable of studying a wide range of sample from materials science, for example, nanoparticles, and biological samples such as proteins and cells in liquid [1]. Different experimental systems are presented, and the physics of image formation is discussed. The obtained spatial resolution is typically limited by ration damage [2], but damage mitigation by at least an order of magnitude is possible [3]. The full scale application of LP-EM for soft matter research still faces several challenges but strategies to to overcome them are emerging, so that time-resolved imaging of processes in soft-matter samples seems within reach [4].  

Employing the unique capabilities of LP-EM, we studied the spatial organization of the membrane protein HER2 in cancer cells. This protein is a member of the epidermal growth factor receptors (EGFRs), and plays an important role in breast cancer aggressiveness and progression. Breast cancer cells were examined by labeling HER2 proteins with quantum dot (QD) nanoparticles for correlative fluorescence microscopy and LP-EM [5]. We discovered a small sub-population of cancer cells with a different response to a prescription drug indicating a possible relevance for studying the role of cancer cell heterogeneity in the development of drug resistance, and studied biopsie samples from patients [6].

LP-EM was also used to directly image dynamic self-assembly behavior of nanoparticles in liquid from which the interplay between nanoparticle shape, ligand shell structure, and substrate–nanoparticle interactions was studied [7].

References:

• 1.    Nat Nanotechnol 6, 695 (2011).
• 2.    Nat Rev Mater 4, 61 (2019).
• 3.    Nano Lett 18, 7435 (2018).
• 4.    Adv Mater 32, 2001582 (2020).
• 5.    Sci Adv 1, e1500165 (2015).
• 6.    Mol Med 25, 42 (2019).
• 7.    Adv Mater 34, 2109093 (2022).