ISL Colloquium in the Auditorium of IOGS

ISL Colloquium (by Sandrine LEVEQUE-FORT, from ISMO), in the IOGS Auditorium, at 11:00 a.m. on 14 September 2022 and by videoconference, on the topic: "Exceeding the diffraction limit in fluorescence microscopy".

Abstract: "Fluorescence microscopy is a reference tool in the study of biological systems, combining the specificity offered by fluorescence and the possibility of morphological and functional monitoring in vivo. Recent developments, which were awarded the Nobel Prize in Chemistry, have made it possible to overcome the diffraction limit and thus to access information at the nanometric scale that was previously inaccessible. In particular single molecule localisation techniques (PALM/STORM)(1-3), allow lateral localisation accuracies of a few nanometres. However, as with all super-resolution techniques, the improvement in the axial direction remains a major challenge in order to move towards a nanoscope with isotropic resolution and also capable of imaging at depth (several tens of microns)(4).
After an introduction to the field, I will present various developments carried out at the ISMO to meet this need for quantitative 3D imaging, illustrated by different biological applications. In particular, we directly exploit intrinsic properties of fluorophores such as their near field to localise them axially(5-7) and thus respond to problems of cell adhesion in particular. To position the individual fluorescent emitters at great depth (several tens of microns), we use a different strategy, based on the introduction of a temporally modulated excitation that allows the fluorphores to be located via the phase of their modulated signal with uniform precision below 7 nm(8).
I will conclude with the current perspectives of the field, and will also show that beyond applications in biology, the localisation of
single molecules can also be used in the observation of nanostructured materials (9, 10).

1. W. E. Moerner, Accounts of Chemical Research 29, 563–571 (1996).
2. S. T. Hess, et al., Biophysical Journal 91, 4258–4272 (2006).
3. M. J. Rust, et al., Nature Methods 3, 793–796 (2006).
4. A. von Diezmann, et al., Chemical Reviews 117, 7244–7275 (2017).
5. N. Bourg, et al., Nature Photonics 9, 587–593 (2015).
6. C. Cabriel, et al., Nature Commun 10, 1–10 (2019).
7. T. Orré, et al., Nature Commun 12, 3104 (2021).
8. P. Jouchet, et al., Nature Photonics, 1–8 (2021).
9. G. Cattinari, et al., ACS Appl. Nano Mater. 4, 6722–6733 (2021).
10. A. F. Koenderink et al., Nanophotonics, 11, 169 (2022)."