Ludovic Jullien

Sustained autocatalysis coupled to compartment growth and division is a key step in the origin of life, but an experimental demonstration of this phenomenon in an artificial system has previously proven elusive. We show that autocatalytic reactions within compartments—when autocatalysis, and reactant and solvent exchange outpace product exchange—dr...

Here we present a method to reduce the photobleaching of fluorescent proteins and the associated phototoxicity. It exploits a photophysical process known as reverse intersystem crossing, which we induce by near-infrared co-illumination during fluorophore excitation. This dual illumination method reduces photobleaching effects 1.5–9.2-fold, can be e...

Metallaphotoredox catalyzed cross-coupling of an arylbromide (Ar-Br) with an alkyl bis-catecholato silicate (R-Si⊖) has been analyzed in depth using a continuum of analytical techniques (EPR, fluorine NMR, electrochemistry, photophysics) and modeling (micro-kinetics and DFT calculations). These studies converged on the impact of four control parame...

The complex kinetics of reversibly photoswitchable fluorescent proteins (RSFPs) is exploited in biological imaging. We analyze the fluorescence evolution of RSFPs submitted to two-color illumination at different light intensities appropriately chosen to change the rate-limiting steps of photoswitching. Starting from a reasonable seven-state photosw...

The Cover Feature shows the principle of HIGHLIGHT, a simple and general strategy to selectively image a reversibly photoactivatable fluorescent label associated with given kinetics. HIGHLIGHT uses specific frequencies and mean light intensities (I1, I2) associated with resonances of the amplitudes of concentration or fluorescence oscillations at h...

The zebrafish is one of the most widely adopted animal models in both basic and transla-tional research. This popularity of the zebrafish results from several advantages such as a high degree of similarity to the human genome, the ease of genetic and chemical perturbations, external fertilization with high fecundity, transparent and fast-developing...

Titration without separation, e.g. quantification of a target species in living cells, is a challenge of analytical chemistry. We perform the selective detection of a target using the kinetics involved in a photochemical process and develop a correlation method that we illustrate by the titration of a fluorescent photoswitcher and the target of a p...

We introduce HIGHLIGHT as a simple and general strategy to selectively image a reversibly photoactivatable fluorescent label associated with a given kinetics. The label is submitted to sine‐wave illumination of large amplitude, which generates oscillations of its concentration and fluorescence at higher harmonic frequencies. For singularizing a lab...

Arylborinic acids represent new, efficient, and underexplored hydrogen peroxide‐responsive triggers. In contrast to boronic acids, two concomitant oxidative rearrangements are involved in the complete oxidation of these species, which might represent a major limitation for an efficient effector (drug or fluorophore) release. Herein, we describe a c...

Photosensitization of organogold intermediates is an emerging field in catalysis. In this context, an access to 2,3-disubstituted indoles from o-alkynyl aniline and iodoalkyne derivatives via a gold-catalyzed sequence under visible-light irradiation and in the absence of an exogenous photocatalyst was uncovered. A wide scope of the process is obser...

Due to its sensitivity and versatility, fluorescence is widely used to detect specifically labeled biomolecules. However, fluorescence is currently limited by label discrimination, which suffers from the broad full width of the absorption/emission bands and the narrow lifetime distribution of the bright fluorophores. We overcome this limitation by...

Donor-acceptor Stenhouse Adducts (DASAs) are reversibly photoswitchable dyes able to interconvert between a red/NIR absorbing triene-like state and a colorless cyclic state. Although optically attractive for multiple applications, their low solubility and lack of photoswitching in water impede their use in aqueous environments. We developed water-s...

Significance Hydrogen peroxide plays an important role in the fine balance between physiological and pathological processes. To detect this diffusible small molecule, we expanded the scope of organic triggers in developing borinic acids as an alternative and more sensitive trigger than the most conventional boronate-based sensors. We discovered tha...

A self-immolative spacer based on disymetrical N,N’ bis carbamate aniline is introduced to liberate a substrate from a precursor after dual activation. The proof of principle of its exclusive selectivity...

Biocompatible fluorescent reporters with spectral properties spanning the entire visible spectrum are indispensable tools for imaging the biochemistry of living cells and organisms in real time. Here, we report the engineering of a fluorescent chemogenetic reporter with tunable optical and spectral properties. A collection of fluorogenic chromophor...

A novel access to 2,3-disubstituted indoles from o-alkynyl aniline and iodoalkyne derivatives via a gold-catalyzed sequence under visible-light irradiation and in the absence of an exogenous photocatalyst was uncovered. A wide scope of the process was observed. Of note, 2-iodo-ynamides that have never been used in any organometallic cross-coupling...

A novel access to 2,3-disubstituted indoles from o-alkynyl aniline and iodoalkyne derivatives via a gold-catalyzed sequence under visible-light irradiation and in the absence of an exogenous photocatalyst was uncovered. A wide scope of the process was observed. Of note, 2-iodo-ynamides that have never been used in any organometallic cross-coupling...

Pharmacological inactivation of antitumor drugs toward healthy cells is a critical factor in prodrug development. Typically, pharmaceutical chemists graft temporary moieties to existing antitumor drugs to reduce their pharmacological activity as much as possible. Here, we report a platform where the structure of the prodrug excludes the preexisting...

Pharmacological inactivation of antitumor drugs toward healthy cells is a critical factor in prodrug development. Typically, pharmaceutical chemists graft temporary moieties to existing antitumor drugs to reduce their pharmacological activity as much as possible. Here, we report a platform where the structure of the prodrug excludes the preexisting...

Observing the localization, the concentration, and the distribution of proteins in cells or organisms is essential to understand theirs functions. General and versatile methods allowing multiplexed imaging of proteins under a large variety of experimental conditions are thus essential for deciphering the inner workings of cells and organisms. Here,...

Starting from simple examples of chemical schemes for which a concentration or an extent of reaction can be eliminated, we highlight the common features of the quasi-steady-state approximation and the partial-equilibrium approximation. General conditions to apply either of these adiabatic eliminations are mentioned.<br

Fluorescence imaging has become a powerful tool for observations in biology. Yet it has also encountered limitations to overcome optical interferences of ambient light, autofluorescence, and spectrally interfering fluorophores. In this account, we first examine the current approaches which address these limitations. Then we more specifically report...

pre>Classical approximations in chemical kinetics, the quasi-steady-state approximation (QSSA) and the partial-equilibrium approximation (PEA), are used to reduce rate equations for the concentrations and the extents of the reaction steps, respectively. We make precise two conditions on the rate constants necessary and sufficient to eliminate a wel...

Composed of a reversibly photoswitchable unit allosterically linked to a sensing module, reversibly photoswitchable sensors (rs-sensors) represent a new and attractive strategy to quantitatively read-out analyte concentrations. However, their kinetic response to illumination is complex, and much attention is required from the design to the applicat...

Fluorescent reporters are essential tools in cell biology for imaging the dynamics of proteins in living cells and organisms with high spatial and temporal resolution. Chemogenetic systems made of a genetically encoded protein tag acting as an anchor for synthetic fluorophores combine the targeting selectivity of genetic tags with the advantages of...

[This corrects the article DOI: 10.1021/acsomega.0c00957.].

Noninvasiveness, minimal handling, and immediate response are favorable features of fluorescence readout for high-throughput phenotyping of labeled plants.Yet, remote fluorescence imaging may suffer from an autofluorescent background and artificial or natural ambient light. In this work, the latter limitations are overcome by adopting reversibly ph...

Fluorescence has become a ubiquitous observable in biology. Yet it encounters limitations, which may originate from optical interferences such as ambient light, autofluorescence, and spectrally interfering fluorophores. In this review, we first report on dynamic contrast which can overcome these limitations. Then we specifically describe Out-of-Ph...

Detection of hydrogen peroxide (H₂O₂), which is responsible for numerous damages when overproduced, is crucial for a better understanding of H₂O₂-mediated signalling in physiological and pathological processes. For this purpose, various“ off-on ” small fluorescent probes relying on a boronate trigger have...

To interrogate living cells requires sensitive imaging of a large number of components in real time. State-of-the-art of multiplexed imaging is routinely limited to a few components. This review reports...

Polyps of the cnidarian Hydra maintain their adult anatomy through two developmental organizers, the head organizer located apically and the foot organizer basally. The head organizer is made of two antagonistic cross-reacting components, an activator, driving apical differentiation and an inhibitor, preventing ectopic head formation. Here we chara...

The well-established oxidative addition–reductive elimination pathway is the most followed one in transition metal-catalysed cross-coupling reactions. While readily occurring with a series of transition metals, gold(i) complexes have shown some reluctance to undergo oxidative addition unless special sets of ligands on gold(i), reagents or reaction...

Fiber-optic epifluorescence imaging with one-photon excitation benefits from its ease of use, cheap light sources, and full-frame acquisition, which enables it for favorable temporal resolution of image acquisition. However, it suffers from a lack of robustness against autofluorescence and light scattering. Moreover, it cannot easily eliminate the...

The use of light to control the expression of genes and the activity of proteins is a rapidly expanding field. While many of these approaches use a fusion between a light activatable protein and the protein of interest to control the activity of the latter, it is also possible to control the activity of a protein by uncaging a specific ligand. In t...

In micro-and macro-scale fluorescence imaging, Speed Out-of-Phase Imaging after Optical Modulation (Speed OPIOM) is shown to be highly efficient for multiplexed fluorescence imaging in the presence of autofluorescence and ambient light.

An apparatus for performing photochemical measurements on a liquid or liquid-containing sample (LS) comprising: a light generating system (LGS), an optical system (OS) configured for directing light from the light generating system towards the sample and a sensing system (SS, SS’) for measuring at least one optical property of the sample, character...

Fluorescence imaging at the macroscale will become easier and more sensitive thanks to a new optical procedure, which uses photoswitchable fluorescent tags. Until now, observing signals from the fluorescent labels has been hampered by interference due to external light or the natural fluorescence of other chemicals in a biological sample or in the...

In order to design a dynamic titration method, we propose a theoretical model harnessing the kinetic properties of the complexation of the titrated species with a titrating photoswitchable reagent. Forced oscillations of illumination are imposed and concentration oscillations of the targeted species are deduced from the equations of chemical kineti...

An original and mild synthetic route for the preparation of novel azafluorenones and derivatives via a ruthenium-mediated [2 + 2 + 2] cycloaddition of α,ω-diynes and cyanamides has been developed. This atom-economical catalytic process demonstrated remarkable regioselectivities to access fluorescent azafluorenone derivatives. The photophysical prop...

Spatiotemporal control of molecular distribution is much in demand in many fields of Chemistry. To address this goal, we exploit a low molecular weight branched self-immolative architecture, which acts as...

The use of light to control the expression of genes and the activity of proteins is a rapidly expanding field. While many of these approaches use a fusion between a light activable protein and the protein of interest to control the activity of the later, it is also possible to control the activity of a protein by uncaging a specific ligand. In that...

The Peer Review File associated with this Article was updated shortly after publication to redact from the authors' point-by-point response a description of unpublished work describing how Speed OPIOM may in future be used to facilitate discrimination between FRET and direct excitation.

The zebrafish has become an increasingly popular and valuable cancer model over the past few decades. While most zebrafish cancer models are generated by expressing mammalian oncogenes under tissue-specific promoters, here we describe a method that allows for the precise optical control of oncogene expression in live zebrafish. We utilize this tech...

We present speed out-of-phase imaging after optical modulation (OPIOM), which exploits reversible photoswitchable fluorophores as fluorescent labels and combines optimized periodic illumination with phase-sensitive detection to specifically retrieve the label signal. Speed OPIOM can extract the fluorescence emission from a targeted label in the pre...

Fluorogen-binding tags, which activate the fluorescence of a specific chromophore (so-called fluorogen) upon reversible binding, have recently been proposed as a way of reducing photobleaching via fluorogen renewal. However, no generic methodology has been proposed to systematically analyze the photodamage of the fluorogen and the protein tag. Usin...

Adult zebrafish have the remarkable ability to regenerate their heart upon injury, a process that involves limited dedifferentiation and proliferation of spared cardiomyocytes (CMs), and migration of their progeny. During regeneration, proliferating CMs are detected throughout the myocardium, including areas distant to the injury site, but whether...

Yellow Fluorescence-Activating and absorption-Shifting Tag (Y FAST, hereafter called FAST) is a 14-kDa protein tag giving a bright green-yellow fluorescent complex upon interaction with the fluorogenic dye 4-hydroxy-3-methylbenzylidene rhodanine (HMBR). Here, we report a collection of fluorogens enabling to tune the fluorescence color of FAST from...

Kinetic analysis of disassembly of self-immolative spacers based on cyclisation processes was performed. Five compounds were synthesized belonging to two different series, and their kinetic constants were determined. Electro-donating substituents gave a slight acceleration but the main effect was steric, and the Thorpe-Ingold effect was indeed part...

Fluorogenic chromophores have been used recently for fluorescence reporting and biosensing. Their ability to turn on upon specific interaction with a given target has been exploited in particular for the design of fluorogen-based reporters enabling biomolecule labeling and imaging. In this paper, we report the development and exhaustive characteriz...

The Inside Cover picture illustrates the principle of cell imaging under kinetic control, in which the temporal modulation of a control parameter P(t), and consequently the observable O(t), allows a kinetically filtered image to be extracted, revealing the distribution of only the targeted cell component. More information can be found in the Minire...

The external control of biologically-active substrates with high spatial and temporal resolutions has already strongly impacted many fields of Biology. This lecture will illustrate how light can be used to control and analyze biological processes.

This paper presents Yellow Fluorescence-Activating and absorption-Shifting Tag (Y-FAST), a small monomeric protein tag, half as large as the green fluorescent protein, enabling fluorescent labeling of proteins in a reversible and specific manner through the reversible binding and activation of a cell-permeant and nontoxic fluorogenic ligand (a so-c...

Living cells are chemical mixtures of exceptional interest and significance, whose investigation requires the development of powerful analytical tools fulfilling the demanding constraints resulting from their singular features. In particular, multiplexed observation of a large number of molecular targets with high spatiotemporal resolution appears...

Genetic labeling techniques allow for noninvasive lineage tracing of cells in vivo. Two-photon inducible activators provide spatial resolution for superficial cells, but labeling cells located deep within tissues is precluded by scattering of the far-red illumination required for two-photon photolysis. Three-photon illumination has been shown to ov...