Nanoscopic Quantitative X-ray Fluorescence Imaging of Cells with a High Energy X-ray Cryo Nano-probe and cryo-correlative microscopy

Session

Stream 3: Chemical Imaging of Biological Samples using Electron, Ion and X-ray Based Techniques

Authors

Dr Sylvain BOHIC (2), Dr Alexandra Pacureanu (1), Dr Peter Cloetens (1), Dr Dmitry Karpov (1), Prof Gerard Jaouen (3), Dr Siden TOP (3)

Affiliations

1. ESRF
2. Inserm UA7 Strobe
3. Sorbonne Universite

Keywords

X-ray nanoprobe, intracellular metal imaging, cryo-correlative microscopy, chemical imaging, organometallic compounds

Abstract text

Several essential metal ions participate in the control of numerous metabolic and signaling pathways, but their rich coordination chemistry and redox properties confer them a propensity to randomly coordinate and catalytically react inside the cell with protein sites other than those tailored for that purpose. A number of sophisticated networks of trafficking pathways are available to tightly regulate their uptake, intracellular transport and compartmentalization, and to avoid their toxic side effects. Cutting-edge technique providing quantitative imaging for detailed study of elemental homeostasis or the intracellular distribution of metal-based drugs at biologically relevant concentration in a label-free fashion is highly desirable. The synchrotron X-ray fluorescence (XRF) nanoprobe as developed today provide the required sensitivity and spatial resolution to elucidating the 2D and 3D distribution, concentration of elements particularly metals inside entire cells at the organelle level. The new state-of-the-art Nano-Imaging beamline ID16A-NI at ESRF offers unique capabilities for X-ray imaging at nanometer scale at high energies (~30nm at 17kev) [1]. It is particularly well suited for the investigation of biological samples at high spatial resolution, e.g. combined hard X-ray phase imaging and XRF detection and quantification of trace elements [2]. A critical issue is to best preserve the structural and chemical integrity of the cells. As it has been demonstrated in electron microscopy or recently for synchrotron 3D-XRF [3], a cryogenic workflow including cryo-immobilization of the cell and cryotransfer to a cryo-scanning stage allow an optimal elemental preservation at subcellular level as close as possible to their native state. In this work, we will illustrate the unique capabilities of this techniques to provide insight in the intracellular targeting of new organometallic drugs [3] on breast cancer cells but also on the fate of metal-based nanoparticles on cancer cells. We will try to underline the importance of correlative sub-cellular imaging for better understanding of the role of metals in cells

References

1.   J. C. Da Silva et al, Optica 2017, 4, 492. 

2.   Bohic S. et al., Journal of Structural Biology, 2012, 177, 248.

3.   Fus F. et al, Angwendte Chemie. 2019, doi: 10.1002/anie.201812336.