EventProf. Ludovic Jullien

A Chemist View on Real Time Multiplexed Fluorescence Imaging in Vivo

Fluorescence microscopy is widely used to image biological samples. Contrast generally results from the brightness of the probe. The emission wavelength is traditionally further used to distinguish fluorophores. However, even with appropriate band pass filters, only three or four probes can be distinguished since emission bands are rather broad and tend to overlap (spectral crowding). Detecting individual emitters with similar emission properties in multiplexed observations thus requires efficient discrimination strategies. Our group has recently introduced two propositions.

FAST (Fluorescence-Activating and absorption-Shifting Tag) is a small monomeric protein tag enabling to fluorescently label proteins in a specific manner through the reversible binding and activation of a cell-permeant and non-toxic fluorogenic ligand. This feature permits to rapidly label and unlabel proteins by addition and withdrawal of the fluorogen (sequential labeling).[1-3]

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OPIOM (Out-of-Phase Imaging after Optical Modulation) adopts a different strategy.[2-4] It exploits reversible photoswitchable fluorescent labels and combines periodic illumination with phase-sensitive detection to specifically retrieve the signal from a targeted label, even in the presence of spectrally interfering fluorophores and autofluorescence.

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[1] M.-A. Plamont et al, Proc. Nat. Acad. Sci. USA, 2016, 113, 497; [2] C. Li et al, Chem. Sci., 2017, 8, 5598; [3] F. M. Pimenta et al, Sci. Rep., 2017, 7, 12316; [4] J. Quérard et al, Angew. Chem. Int. Ed., 2015, 54, 2633; [5] J. Quérard et al, Chem. Sci., 2015, 6, 2968; [6] J. Quérard et al, ChemPhysChem, 2016, 17, 1396; [7] J. Quérard et al, Nat. Commun., 2017, 8, 969.

About The Speaker

ludovic-jullien

Prof. Ludovic Jullien has been trained as a chemist at Ecole Normale Supérieure (ENS, Paris) and University Pierre et Marie Curie (UPMC, Paris). After his PhD (Prof. Jean-Marie Lehn, Collège de France, Paris) and his post-doc (Prof. Helmut Ringsdorf, Mainz, Germany), he became Research Assistant at CNRS (Collège de France) and then Professor at UPMC and ENS. He is driven by a strong interest for the triple interface between Biology, Chemistry, and Physics, with expertise in Systems Chemistry, Supramolecular Chemistry, Biophysical Chemistry, Analytical Chemistry, and Thermokinetics.