Séminaire présenté par : Niels de Jonge

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).

Séminaire général IPCMS-CNRS présenté par : M. Kaesmann du ministère de l’intérieur

Résumé : Le séminaire propose une sensibilisation des personnels quel que soit leur positionnement hiérarchique, ainsi que des personnels administratifs exerçant des missions de support à destination des laboratoires de recherche. Elle a pour objectif de permettre une prise de conscience des points de vulnérabilité propres au secteur de la recherche afin de prévenir le risque de compromission par un acteur étranger.

Contact : pierre.rabu@ipcms.unistra.fr, en collaboration avec la Délégation Régionale du CNRS

Séminaire DCMI – Axes 4 et 5 présenté par Paul STEADMAN

Speaker: Paul STEADMAN (Responsable de la ligne I10 au Synchroton Diamond)

Abstract : A study of the electric current induced hysteresis in Pt/CoFeTaB thin films revealed an unexpected behaviour in the hysteresis curves measured using polarised soft X-ray reflectivity [1]. Following a detailed study of the polarisation dependence of the reflected intensity [2] both detailed calculations and experimental data revealed that the switching is Y type (magnetisation switching perpendicular to the current), is very sensitive to external magnetic fields and that, rather bizarrely, only part of the film is switching. In addition the importance of non-linear dependence on the magnetic scattering and its dependence on polarisation and energy have been uncovered experimentally and explained with a very simple model.

  • [1] D. M. Burn, R. Fan, O. Inyang, M. Tokac¸ L. Bouchenoire, A. T. Hindmarch and P. Steadman, P. (2022). Phys. Rev. B, 106, 094429.
  • [2] Raymond Fan, Kiranjot, Razan O. M. Aboljadayel, Kalel Alsaeed, Peter, J. Synchrotron Rad. (2024). 31, 493–507