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Chemistry: releasing two fluorophores into living cells by "click and release".

Researchers from the Laboratoire de Marquage au Carbone-14 (LMC) have developed a new series of iminosydnones that can split in half and release two fluorophores. They are providing a proof of concept that this "click and release" reaction can be triggered in living cells. The study was published in Chemical Communications

Published on 29 June 2020

For the past ten years, the LMC (14-carbone labeling laboratory) has been actively contributing to the development of a chemistry that works in the most complex living systems. This so-called bio-orthogonal chemistry is used to modify biological material as desired and with unequalled performance. It enables a molecule of biological interest to be linked to a label ("click"), to selectively break bonds in order to release molecules ("release"), or to combine both ("click and release").

In the case of click and release reactions, LMC has developed a series of molecules, iminosydnones, which are capable of reacting rapidly in biological media with cycloalkynes because of their mesoionic core to form two new products: one resulting from the ligation of the two reaction partners (click), the other from the fragmentation of the iminosydnone (release). From this approach, LMC researchers wish to produce fluorescent bioconjugates (proteins, peptides, drugs...), of great interest in pharmacology, especially for all imaging studies of pharmacokinetics and pharmacodynamics. They have designed a new series of iminosydnones: these are made up of two fluorophores which are quenched because of their position around the mesoionic core. During a click and release reaction with a cycloalkyne, one of the two fluorophores of the iminosydnone is clipped to the cycloalkyne and the other is "free". Most importantly, both fluorophores are "turned-on". Researchers show that this click and release reaction can take place in fixed or living cells. These in vivo experiments are a proof of concept: they confirm the compatibility of this reaction inside cells and the possibility to follow the release of the two products.

In summary, these new versatile iminosydnones can be considered as fluorogenic cleavable linkers allowing the cellular tracking of the two products generated from the click and release reaction. These new tools should therefore find interesting applications in drug delivery by allowing the tracking of both the released drug and its vector.

Contact : Frédéric Taran (

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