Research projects

This research focus aims to develop fluorescent probes capable of modulating their fluorescence properties under light irradiation. We have established a new mechanism called directed photo-oxidation, enabling the development of such probes. Among them, photoconvertible probes change their emission color upon irradiation, whereas photoactivatable probes activate their fluorescence emission. Our probes from the BrightSwitch® family can be functionalized and thus target different organelles or cellular environments. These photoswitching properties also allow their use in super-resolution microscopy based on single-molecule localization microscopy (SMLM).

Aim:

Our aim now is to control the directed photo-oxidation mechanism through its application to other fluorescent systems and through a deeper understanding of the different steps involved.

Selected Publications:

Saladin L., Breton V., Le Berruyer V., Nazac P., Lequeu T, Didier P., Danglot, L., Collot, M. Targeted Photoconvertible BODIPYs Based on Directed Photooxidation-Induced Conversion for Applications in Photoconversion and Live Super-Resolution Imaging.  J. Am. Chem. Soc.2024.

Saladin L., Dal Pra O., Klymchenko A. S., Didier P., Collot M. Tuning Directed Photooxidation-Induced Conversion of Pyrrole-Based Styryl Coumarin Dual-Color Photoconverters. Chem. – Eur. J., 2023, 29.

Saladin L., Breton V., Dal Pra O., Klymchenko A. S., Danglot L., Didier P., Collot M. Dual-Color Photoconvertible Fluorescent Probes Based on Directed Photooxidation Induced Conversion for Bioimaging. Angew. Chem. Int. Ed.2023, 62 (4), e202215085.

This research focus aims to develop fluorescent molecular probes that are selective, multicolor, bright, and capable of efficiently labeling an organelle, a protein of interest (via Halo-tag), a receptor, or a specific subcellular environment. These probes are also designed to detect environmental or physicochemical variations ([Ca²⁺], pH, polarity, viscosity, etc.) using various fluorescence imaging techniques (two-photon imaging, FLIM, FRET, ratiometric imaging, etc.). Our team is renowned for its fluorescent probes. Some have been brought to market, such as the membrane probes MemBright®, the lipid droplet probes LipiBright®, and calcium probes like Calcium Ruby-Nano.

Aim:

The objective of this research focus is to better understand the mechanisms of selective targeting of fluorophores to subcellular compartments and to develop systems that allow for quantitative and stable measurements over time. Another goal is to extend the applications of these probes to various more complex living samples (organoids, tissues, or whole organisms), whether they are plant, marine, or animal.

Selected Publications:

Michelis S., Danglot L., Vauchelles R., Klymchenko A. S, Collot M.  Imaging and Measuring Vesicular Acidification with a Plasma Membrane-Targeted Ratiometric pH Probe. Anal. Chem.2022, 94 (15), 5996–6003.

Collot M., Ashokkumar P., Anton H., Boutant E., Faklaris O., Galli T., Mély Y., Danglot L., Klymchenko, A. S. MemBright: A Family of Fluorescent Membrane Probes for Advanced Cellular Imaging and Neuroscience. Cell Chem. Biol.2019, 26 (4), 600-614.e7.

Collot M., Fam T. K., Ashokkumar P., Faklaris O., Galli T., Danglot L., Klymchenko, A. S. Ultrabright and Fluorogenic Probes for Multicolor Imaging and Tracking of Lipid Droplets in Cells and Tissues. J. Am. Chem. Soc.2018, 140 (16), 5401–5411.

This research area is dedicated to the development of fluorescent and nanostructured photoresponsive systems, primarily in the form of nanoparticles. Our main approach is based on the covalent bonding of molecular probes to polymers, which, after a formulation step, allows for the creation of polymer nanoparticles. This approach enables 1) the production of stealth, ultrabright and very small systems (Down to <10 nm) and 2) a better understanding of the physicochemistry of the nanoparticles and the associated release phenomena.

Aim:

Building upon these highly luminescent nanosystems, our aim is to develop probes capable of 1) detecting very subtle changes (such as [Ca²⁺], pH, polarity, viscosity, etc.) in complex biological environments, including through in vivo imaging, and 2) releasing molecules of interest in a controlled manner triggered by specific stimuli, particularly light.

Selected Publications:

Bou S., Klymchenko A. S., Collot M. Fluorescently Labeled Branched Copolymer Nanoparticles for In Situ Characterization of Nanovectors and Imaging of Cargo Release. ACS Appl. Nano Mater.2022, 5 (3), 4241–4251.

Collot M., Schild J., Fam K. T., Bouchaala R., Klymchenko A. S. Stealth and Bright Monomolecular Fluorescent Organic Nanoparticles Based on Folded Amphiphilic Polymer. ACS Nano2020, 14 (10), 13924–13937.

Wang X., Anton N., Ashokkumar P., Anton H., Fam T. K., Vandamme T., Klymchenko A. S., Collot, M. Optimizing the Fluorescence Properties of Nanoemulsions for Single Particle Tracking in Live Cells. ACS Appl. Mater. Interfaces 2019, 11 (14), 13079–13090.

• Fluorescent probes for super-resolution microscopy in live cells (live SMLM) | ANR.
• Development of pH-sensitive fluorescent probes for cerebral vascular imaging | ANR | France Life Imaging.
• Formulation of antibiotics and pro-antibiotics using nanoemulsions to combat pulmonary infections | ANR.
• Development of fluorescent probes selectively targeted to organelles for cellular imaging | SATT Conectus.