Publications by authors named "Cyrille Monnereau"

37 Publications

Light-induced in situ chemical activation of a fluorescent probe for monitoring intracellular G-quadruplex structures.

Nanoscale 2021 Aug 4;13(32):13795-13808. Epub 2021 Aug 4.

Department of Medical Biochemistry and Biophysics, Umeå University, 90187 Umeå, Sweden.

Light-activated functional materials capable of remote control over duplex and G-quadruplex (G4) nucleic acids formation at the cellular level are still very rare. Herein, we report on the photoinduced macrocyclisation of a helicenoid quinoline derivative of binaphthol that selectively provides easy access to an unprecedented class of extended heteroaromatic structures with remarkable photophysical and DNA/RNA binding properties. Thus, while the native bisquinoline precursor shows no DNA binding activity, the new in situ photochemically generated probe features high association constants to DNA and RNA G4s. The latter inhibits DNA synthesis by selectively stabilizing G4 structures associated with oncogenic promoters and telomere repeat units. Finally, the light sensitive compound is capable of in cellulo photoconversion, localizes primarily in the G4-rich sites of cancer cells, competes with a well-known G4 binder and shows a clear nuclear co-localization with the quadruplex specific antibody BG4. This work provides a benchmark for the future design and development of a brand-new generation of light-activated target-selective G4-binders.
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http://dx.doi.org/10.1039/d1nr02855cDOI Listing
August 2021

Exploring the Concept of Dimerization-Induced Intersystem Crossing: At the Origins of Spin-Orbit Coupling Selection Rules.

J Phys Chem B 2021 08 22;125(30):8572-8580. Epub 2021 Jul 22.

Univ Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, F-69342 Lyon, France.

Singlet-triplet interconversions (intersystem crossing, ISC) in organic molecules are at the basis of many important processes in cutting-edge photonic applications (organic light-emitting devices, photodynamic therapy, etc.). Selection rules for these transitions are mainly governed by the spin-orbit coupling (SOC) phenomenon. Although the SOC relies on complex relativistic phenomena, theoreticians have, with time, developed increasingly sophisticated and efficient approaches to gain access to a satisfactory evaluation of its magnitude. However, recent works have highlighted the remarkable and somehow unexpected efficiency of dimers of small conjugated molecules in terms of ISC quantum yields, whose origin has not been completely investigated. In this work, we bring a coupled experimental and theoretical analysis of the origin of the unusually large ISC efficiency on a series of such dimers that differ by their nature (covalent or supramolecular). We show that considering the dynamical nature of the SOC, and especially its dependence on angular orientations between the dimer subunits sometimes overlooked in the literature, it is necessary to rationalize some counterintuitive experimental observations. This combined experimental and theoretical work paves the way for new molecular engineering rules for SOC control.
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http://dx.doi.org/10.1021/acs.jpcb.1c05082DOI Listing
August 2021

Metal-Free Visible-Light Synthesis of Arylsulfonyl Fluorides: Scope and Mechanism.

Chemistry 2021 Jun 11;27(34):8704-8708. Epub 2021 May 11.

Institute of Chemistry and Biochemistry (ICBMS-UMR CNRS 5246), Univ Lyon, Université Lyon 1, CNRS, CPE-Lyon, INSA 43 Bd du 11 Novembre 1918, 69622, Villeurbanne, France.

The first metal-free procedure for the synthesis of arylsulfonyl fluorides is reported. Under organo-photoredox conditions, aryl diazonium salts react with a readily available SO source (DABSO) to afford the desired product through simple nucleophilic fluorination. The reaction tolerates the presence of both electron-rich and -poor aryls and demonstrated a broad functional group tolerance. To shed the light on the reaction mechanism, several experimental techniques were combined, including fluorescence, NMR, and EPR spectroscopy as well as DFT calculations.
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http://dx.doi.org/10.1002/chem.202101056DOI Listing
June 2021

Reevaluating the Solution Photophysics of Tetraphenylethylene at the Origin of their Aggregation-Induced Emission Properties.

Chemistry 2021 May 22;27(30):8003-8007. Epub 2021 Apr 22.

UMR 5182, Laboratoire de Chimie, Univ Lyon, ENS Lyon, CNRS, Université Claude Bernard Lyon 1, 69342, Lyon, France.

Although tetraphenylethylene (TPE) and its derivatives have been the most commonly used building blocks in the construction of molecules with aggregation-induced emission (AIE) properties, no absolute consensus exists regarding the mechanisms at the origin of the phenomenon. Restriction of intramolecular rotations (RIR) of peripheral phenyls has historically been a dominant paradigm, which has served as a valuable guideline in the molecular engineering of AIEgens. Yet, an increasing number of recent works have established that photoisomerization or photocyclization may actively participate in the nonradiative dissipation of the excitation energy. In this paper, the first experimental evaluation of the quantum efficiencies of these different processes is reported, and photoisomerization is shown to be by far the dominant photophysical pathway in solution, accounting for virtually all nonradiative decay of the molecule's excited state in degassed solution.
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http://dx.doi.org/10.1002/chem.202100926DOI Listing
May 2021

Forging C-SeCF Bonds with Trifluoromethyl Tolueneselenosulfonate under Visible-Light.

Chem Rec 2021 Feb 27;21(2):417-426. Epub 2021 Jan 27.

Institute of Chemistry and Biochemistry (ICBMS-UMR CNRS 5246), Univ Lyon, Université Lyon 1, CNRS, CPE-Lyon, INSA, 43 Bd du 11 Novembre 1918, 69622, Villeurbanne, France.

This account highlights some of our recent work on photoinduced trifluoromethylselenolation reactions. This research program relies primarily on the design of a new key shelf-stable selenating reagent that can be involved in various radical processes In particular, we demonstrated that trifluoromethylselenolation of arenes, alkenes, alkynes as well as aliphatic organic building blocks can be readily achieved under visible-light irradiation. Mechanistic investigations based on F NMR studies, EPR spectroscopy, cyclic voltammetry and luminescence studies allowed us to shed the light on the different proposed mechanisms in the designed methodologies. The applicative potential of these strategies was further demonstrated through the synthesis of bioactive analogue containing SeCF motif.
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http://dx.doi.org/10.1002/tcr.202000184DOI Listing
February 2021

Determination of Photoinduced Radical Generation Quantum Efficiencies by Combining Chemical Actinometry and F NMR Spectroscopy.

Anal Chem 2021 02 21;93(5):2926-2932. Epub 2021 Jan 21.

Laboratoire de Chimie, Univ. Lyon, ENS Lyon, CNRS, Université Lyon 1, UMR 5182, 46 Allée d'Italie, 69364 Lyon, France.

We introduce a general and relatively straightforward protocol aimed at determining the absolute photoinduced radical generation efficiency via NMR monitoring. This approach relies on the use of a radical scavenger probe that combines a nitroxide moiety that specifically reacts with radicals and a trifluoromethyl group used as a F NMR signaling unit. Using an LED source, whose fluence is precisely determined by a chemical actinometry procedure also described herein, the method is used to determine the radical photogeneration quantum yields of three well-known polymerization initiators: azobisisobutyronitrile (AIBN), 4,4'-bis(,-diethylamino)benzophenone (BDEBP, a derivative of Michler's ethyl ketone), and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (MAPO). The overall good agreement with values previously reported in the literature proves the robustness of this new method. We then extended the study to the precise measurement of the quantum yield of free-radical photogeneration on a newly synthesized photoinitiator used for two-photon direct laser writing. This study highlights the potential of this methodology for the quantitative determination of photoinduced radical generation efficiency used in many fields of applications.
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http://dx.doi.org/10.1021/acs.analchem.0c04540DOI Listing
February 2021

Two-Photon Absorbing AIEgens: Influence of Stereoconfiguration on Their Crystallinity and Spectroscopic Properties and Applications in Bioimaging.

ACS Appl Mater Interfaces 2020 Dec 20;12(49):55157-55168. Epub 2020 Nov 20.

Univ. Lyon, ENS Lyon, CNRS, Université Lyon 1, Laboratoire de Chimie, UMR 5182, 46 Allée d'Italie, 69364 Lyon, France.

This paper aims at designing chromophores with efficient aggregation-induced emission (AIE) properties for two-photon fluorescence microscopy (2PFM), which is one of the best-suited types of microscopy for the imaging of living organisms or thick biological tissues. Tetraphenylethylene (TPE) derivatives are common building blocks in the design of chromophores with efficient AIE properties. Therefore, in this study, extended TPE AIEgens specifically optimized for two-photon absorption (2PA) are synthesized and the resulting (/) isomers are separated using chromatography on chiral supports. Comparative characterization of the AIE properties is performed on the pure () and () isomers and the mixture, allowing us, in combination with powder X-ray diffraction and solid-state NMR, to document a profound impact of crystallinity on solid-state fluorescence properties. In particular, we show that stereopure AIEgens form aggregates of superior crystallinity, which in turn exhibit a higher fluorescence quantum yield compared to diastereoisomers mixtures. Preparation of stereopure organic nanoparticles affords very bright fluorescent contrast agents, which are then used for cellular and intravital two-photon microscopy on human breast cancer cells and on zebrafish embryos.
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http://dx.doi.org/10.1021/acsami.0c15810DOI Listing
December 2020

Photocatalysis Meets Magnetism: Designing Magnetically Recoverable Supports for Visible-Light Photocatalysis.

ACS Appl Mater Interfaces 2020 Jun 18;12(22):24895-24904. Epub 2020 May 18.

Centre for Green Chemistry and Catalysis, Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada.

While magnetic supports have been widely used to immobilize homogeneous catalysts in organic chemistry, this strategy has so far found very little application in photocatalysis. Indeed, magnetic supports are dark colored, and thus compete for photon absorption with photocatalysts themselves. We have developed a series of core-shell Fe(0)-silica nanoparticles as supports for immobilizing the photosensitizer Ru(bpy), featuring various silica shell thicknesses-16-34 nm SiO-on 9 nm Fe cores. The supports and the resulting photocatalytic systems were studied for their magnetic, optical, and catalytic properties in the context of the photooxidation of citronellol, and we found that thicker silica shells lead to higher catalytic activity. We correlated this effect as well as Ru(bpy) fluorescence and singlet oxygen generation to the absorption properties of the supports. We were able to reuse our optimal system three times with minimal loss of activity and achieved turnover numbers largely surpassing the performance of homogeneous Ru(bpy). This work highlights the role of material design in the conception of new supports for applications in heterogeneous photocatalysis.
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http://dx.doi.org/10.1021/acsami.0c06126DOI Listing
June 2020

Theoretical and experimental investigation on the intersystem crossing kinetics in benzothioxanthene imide luminophores, and their dependence on substituent effects.

Phys Chem Chem Phys 2020 Jun 20;22(22):12373-12381. Epub 2020 Apr 20.

Univ. Lyon, ENS Lyon, CNRS, Université Lyon 1, Laboratoire de Chimie, UMR 5182, 46 Allée d'Italie, 69364 Lyon, France.

In spite of their remarkable luminescence properties, benzothioxanthene imide (BTXI, an imide containing rylene chromophores) derivatives have been largely overlooked compared to their perylene bisimide and naphthalene bisimide counterparts. Thus, their detailed photophysics are much less understood. In this paper, we show how relatively simple structural modifications of the backbone of BTXIs can lead to impressive variations in their inter-system crossing kinetics. Thus, through rational engineering of their structure, it is possible to obtain a triplet formation quantum yield that reaches unity, making BTXI a promising class of compounds for triplet-based applications (photodynamic therapy, electroluminescence, etc.).
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http://dx.doi.org/10.1039/d0cp01072cDOI Listing
June 2020

Influence of Polymer Charge on the Localization and Dark- and Photo-Induced Toxicity of a Potential Type I Photosensitizer in Cancer Cell Models.

Molecules 2020 Mar 3;25(5). Epub 2020 Mar 3.

Laboratoire de Chimie, CNRS UMR 5182, ENS de Lyon, Université Lyon 1, F-69342 Lyon, France.

A current trend within photo-dynamic therapy (PDT) is the development of molecular systems targeting hypoxic tumors. Thus, type I PDT sensitizers could here overcome traditional type II molecular systems that rely on the photo-initiated production of toxic singlet oxygen. Here, we investigate the cell localization properties and toxicity of two polymeric anthracene-based fluorescent probes (neutral Ant-PHEA and cationic Ant-PIm). The cell death and DNA damage of Chinese hamster ovary cancer cells (CHO-K1) were characterized as combining PDT, cell survival studies (MTT-assay), and comet assay. Confocal microscopy was utilized on samples incubated together with either DRAQ5, Lyso Tracker Red, or Mito Tracker Deep Red in order to map the localization of the sensitizer into the nucleus and other cell compartments. While Ant-PHEA did not cause significant damage to the cell, Ant-PIm showed increased cell death upon illumination, at the cost of a significant dark toxicity. Both anthracene chromophores localized in cell compartments of the cytosol. Ant-PIm showed a markedly improved selectivity toward lysosomes and mitochondria, two important biological compartments for the cell's survival. None of the two anthracene chromophores showed singlet oxygen formation upon excitation in solvents such as deuterium oxide or methanol. Conclusively, the significant photo-induced cell death that could be observed with Ant-PIm suggests a possible type I PDT mechanism rather than the usual type II mechanism.
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http://dx.doi.org/10.3390/molecules25051127DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7179247PMC
March 2020

Intriguing Effects of Halogen Substitution on the Photophysical Properties of 2,9-(Bis)halo-Substituted Phenanthrolinecopper(I) Complexes.

Inorg Chem 2019 Jun 29;58(12):7730-7745. Epub 2019 May 29.

Chimie Et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM) , UMR 6230, CNRS, Université UNAM , 2 rue de la Houssinière, BP 92208 , 44322 Nantes Cedex 3 , France.

Three new copper(I) complexes [Cu(L)](PF) (where L stands for 2,9-dihalo-1,10-phenanthroline and X = Cl, Br, and I) have been synthesized in order to study the impact of halogen substituents tethered in the α position of the chelating nitrogen atoms on their physical properties. The photophysical properties of these new complexes (hereafter named Cu-X) were characterized in both their ground and excited states. Femtosecond ultrafast spectroscopy revealed that early photoinduced processes are faster for Cu-I than for Cu-Cl or Cu-Br, both showing similar behaviors. Their electronic absorption and electrochemical properties are comparable to benchmark [Cu(dmp)] (where dmp stands for 2,9-dimethyl-1,10-phenanthroline); furthermore, their optical features were fully reproduced by time-dependent density functional theory and ab initio molecular dynamics calculations. All three complexes are luminescent at room temperature, showing that halogen atoms bound to positions 2 and 9 of phenanthroline are sufficiently bulky to prevent strong interactions between the excited Cu complexes and solvent molecules in the coordination sphere. Their behavior in the excited state, more specifically the extent of the photoluminescence efficiency and its dependence on the temperature, is, however, strongly dependent on the nature of the halogen. A combination of ultrafast transient absorption spectroscopy, temperature-dependent steady-state fluorescence spectroscopy, and computational chemistry allows one to gain a deeper understanding of the behavior of all three complexes in their excited state.
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http://dx.doi.org/10.1021/acs.inorgchem.9b00042DOI Listing
June 2019

A "Multi-Heavy-Atom" Approach toward Biphotonic Photosensitizers with Improved Singlet-Oxygen Generation Properties.

Chemistry 2019 Jul 30;25(38):9026-9034. Epub 2019 May 30.

Laboratoire de Chimie de l'ENS de Lyon, Univ Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, 69342, Lyon, France.

Two trispicolinate 1,4,7-triazacyclonane (TACN)-based ligands bearing three picolinate biphotonic antennae were synthetized and their Yb and Gd complexes isolated. One series differs from the other by the absence (L )/presence (L ) of bromine atoms on the antenna backbone, offering respectively improved optical and singlet-oxygen generation properties. Photophysical properties of the ligands, complexes and micellar Pluronic suspensions were investigated. Complexes exhibit high two-photon absorption cross-section combined either with NIR emission (Yb) or excellent O generation (Gd). The very large intersystem crossing efficiency induced by the combination of bromine atom and heavy rare-earth element was corroborated with theoretical calculations. The O generation properties of L Gd micellar suspension under two-photon activation leads to tumour cell death, suggesting the potential of such structures for theranostic applications.
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http://dx.doi.org/10.1002/chem.201901047DOI Listing
July 2019

Visible-light promoted fluoroalkylselenolation: toward the reactivity of unsaturated compounds.

Chem Commun (Camb) 2018 Sep 14;54(71):9909-9912. Epub 2018 Aug 14.

Institute of Chemistry and Biochemistry (ICBMS - UMR CNRS 5246), Unvi. Lyon, Université Lyon 1, CNRS, 43 Bd du 11 novembre 1918, F-69622 Villeurbanne, France.

The reactivity of fluoroalkylselenotoluenesulfonates with unsaturated substrates is explored herein. The direct activation of these shelf-stable reagents under visible light allows the double functionalisation of alkenes or alkynes efficiently, leading to a wide range of β-fluoroalkylselenolated sulfones. Mechanistic investigations have been undertaken supporting the formation of radical intermediates.
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http://dx.doi.org/10.1039/c8cc05256eDOI Listing
September 2018

Two-Photon Macromolecular Probe Based on a Quadrupolar Anthracenyl Scaffold for Sensitive Recognition of Serum Proteins under Simulated Physiological Conditions.

ACS Omega 2017 Sep 12;2(9):5715-5725. Epub 2017 Sep 12.

Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wroclaw University of Science and Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland.

The binding interaction of a biocompatible water-soluble polycationic two-photon fluorophore () toward human serum albumin (HSA) was thoroughly investigated under simulated physiological conditions using a combination of steady-state, time-resolved, and two-photon excited fluorescence techniques. The emission properties of both and the fluorescent amino acid residues in HSA undergo remarkable changes upon complexation allowing the thermodynamic profile associated with -HSA complexation to be accurately established. The marked increase in fluorescence intensity and quantum yield in the proteinous environment seems to be the outcome of the attenuation of radiationless decay pathways resulting from motional restriction imposed on the fluorophore. Fluorescence resonance energy transfer and site-marker competitive experiments provide conclusive evidence that the binding of preferentially occurs within the subdomain IIA. The pronounced hypsochromic effect and increased fluorescence enhancement upon association with HSA, compared to that of bovine serum albumin (BSA) and other biological interferents, makes the polymeric probe a valuable sensing agent in rather complex biological environments, allowing facile discrimination between the closely related HSA and BSA. Furthermore, the strong two-photon absorption (TPA) with a maximum located at 820 nm along with a TPA cross section σ > 800 GM, and the marked changes in the position and intensity of the band upon complexation definitely make a promising probe for two-photon excited fluorescence-based discrimination of HSA from BSA.
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http://dx.doi.org/10.1021/acsomega.7b00665DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6045344PMC
September 2017

Visible-Light-Mediated Metal-Free Synthesis of Trifluoromethylselenolated Arenes.

Angew Chem Int Ed Engl 2018 Sep 1;57(36):11781-11785. Epub 2018 Aug 1.

Institute of Chemistry and Biochemistry (ICBMS-UMR, CNRS 5246), Univ Lyon, Université Lyon 1, CNRS, CPE-Lyon, INSA, 43 Bd du 11 Novembre 1918, 69622, Villeurbanne, France.

The first visible-light-mediated synthesis of trifluoromethylselenolated arenes under metal-free conditions is reported. The use of an organic photocatalyst enables the trifluoromethylselenolation of arene diazonium salts using the shelf-stable reagent trifluoromethyl tolueneselenosulfonate at room temperature. The reaction does not require the presence of any additives and shows high functional-group tolerance, covering a very broad range of starting materials. Mechanistic investigations, including EPR spectroscopy, luminescence investigations, and cyclic voltammetry allow rationalization of the reaction mechanism.
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http://dx.doi.org/10.1002/anie.201806165DOI Listing
September 2018

Specific Recognition of G-Quadruplexes Over Duplex-DNA by a Macromolecular NIR Two-Photon Fluorescent Probe.

J Phys Chem Lett 2017 Dec 22;8(23):5915-5920. Epub 2017 Nov 22.

Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wroclaw University of Science and Technology , Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland.

The implication of guanine-rich DNA sequences in biologically important roles such as telomerase dysfunction and the regulation of gene expression has prompted the search for structure-specific G-quadruplex agents for targeted diagnostic and therapeutic applications. Herein, we report on a near-infrared (NIR) two-photon poly(cationic) anthracene-based macromolecule able to selectively target G-quadruplexes (G4s) over genomic double-stranded DNA. In particular, the striking changes in its linear and third-order nonlinear optical properties, combined with the emergence of a strong induced electronic circular dichroism (ECD) signal upon binding to canonical and noncanonical DNA secondary structures allowed for a highly specific detection of several different G4s. Furthermore, through a detailed computational analysis we bring compelling evidence that our probe intercalation within G4s is a thermodynamically favored event, and we fully rationalize the spectroscopic evolution resulting from this complexation event by providing a reasonable explanation regarding the origin of the peculiar ECD effect that accompanies it.
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http://dx.doi.org/10.1021/acs.jpclett.7b02547DOI Listing
December 2017

Two-Photon Photosensitizer-Polymer Conjugates for Combined Cancer Cell Death Induction and Two-Photon Fluorescence Imaging: Structure/Photodynamic Therapy Efficiency Relationship.

Biomacromolecules 2017 Dec 10;18(12):4022-4033. Epub 2017 Nov 10.

Univ Lyon, INSERM, ENS de Lyon, CNRS, Université Claude Bernard, Centre International de Recherche en Infectiologie (CIRI) , U1111, F-69007 Lyon, France.

One of the challenges of photodynamic therapy is to increase the penetration depth of light irradiation in the tumor tissues. Although two-photon excitation strategies have been developed, the two-photon absorption cross sections of clinically used photosensitizers are generally low (below 300 GM). Besides, photosensitizers with high cross section values are often non-water-soluble. In this research work, a whole family of photosensitizer-polymer conjugates was synthesized via the covalent binding of a photosensitizer with a relatively high cross section along a biocompatible copolymer chain. The resulting photosensitizer-polymer conjugates were water-soluble and could be imaged in cellulo by two-photon microscopy thanks to their high two-photon absorption cross sections (up to 2600 GM in water, in the NIR range). In order to explore the structure/photodynamic activity relationship of such macromolecular photosensitizers, the influence of the polymer size, photosensitizer density, and presence of charges along the polymer backbone was investigated (neutral, anionic, cationic, and zwitterionic conjugates were compared). The macromolecular photosensitizers were not cytotoxic in the absence of light irradiation. Their kinetics of cellular uptake in the B16-F10 melanoma cell line were followed by flow cytometry over 24 h. The efficiency of cell death upon photoactivation was found to be highly correlated to the cellular uptake in turn correlated to the global charge of the macromolecular photosensitizer which appeared as the determining structural parameter.
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http://dx.doi.org/10.1021/acs.biomac.7b01090DOI Listing
December 2017

Access to cyclic gem-difluoroacyl scaffolds via electrochemical and visible light photocatalytic radical tandem cyclization of heteroaryl chlorodifluoromethyl ketones.

Chem Commun (Camb) 2017 May;53(41):5653-5656

Univ Lyon, Université Lyon 1, CNRS, INSA, CPE-Lyon, ICBMS, UMR 5246, 43, Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France.

A variety of unprecedented scaffolds containing a difluoroacyl moiety were obtained in moderate to good yields, with excellent diastereoselectivity, via electrochemical or photochemical activation of difluoroacyl heteroaryles with a series of olefinic substrates.
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http://dx.doi.org/10.1039/c7cc02979aDOI Listing
May 2017

Keto-polymethines: a versatile class of dyes with outstanding spectroscopic properties for and two-photon microscopy imaging.

Chem Sci 2017 Jan 3;8(1):381-394. Epub 2016 Aug 3.

ENS Lyon , Université de Lyon 1 , CNRS Laboratoire de chimie de l'ENS Lyon , UMR 5182 CNRS, 46 allée d'Italie , 69364 Lyon , France . Email: ; Email:

The synthesis of keto-heptamethine derivatives has been expanded to various new symmetrical and asymmetrical structures, including an unprecedented di-anionic keto-polymethine. The spectroscopic behavior of these new dyes has been systematically and thoroughly investigated, revealing that the formation of hydrogen bond interactions with protic solvents is responsible for a dramatic enhancement of the fluorescence quantum yield in the far-red spectral region. The existence of these strong hydrogen-bond interactions was further confirmed by molecular dynamics simulations. These bis-dipolar polymethines exhibit large two-photon absorption (TPA) cross-sections ( in GM) in the near-infrared, making them ideal candidates for NIR-to-NIR two-photon microscopy imaging applications. We demonstrate that the molecular engineering of the hydrophilic/hydrophobic balance enables targeting of different cellular components, such as cytoplasm or cell membranes. Addition of appropriate substituents provides the molecule with high-water-solubility, affording efficient two-photon probes for angiography.
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http://dx.doi.org/10.1039/c6sc02488bDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5365052PMC
January 2017

Ion pairing controls rheological properties of "processionary" polyelectrolyte hydrogels.

Soft Matter 2016 Dec;12(48):9749-9758

Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Villeurbanne, France.

We demonstrated recently that polyelectrolytes with cationic moieties along the chain and a single anionic head are able to form physical hydrogels due to the reversible nature of the head-to-body ionic bond. Here we generate a variety of such polyelectrolytes with various cationic moieties and counterion combinations starting from a common polymeric platform. We show that the rheological properties (shear modulus, critical strain) of the final hydrogels can be modulated over three orders of magnitude depending on the cation/anion pair. Our data fit remarkably well within a scaling model involving a supramolecular head-to-tail single file between cross-links, akin to the behaviour of pine-processionary caterpillar. This model allows the quantitative measure of the amount of counterion condensation from standard rheology procedure.
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http://dx.doi.org/10.1039/c6sm02022dDOI Listing
December 2016

Unravelling the Binding Mechanism of a Poly(cationic) Anthracenyl Fluorescent Probe with High Affinity toward Double-Stranded DNA.

Biomacromolecules 2016 11 12;17(11):3609-3618. Epub 2016 Oct 12.

Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wroclaw University of Science and Technology , Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland.

We report the synthesis, spectroscopy, and the DNA binding properties of a biocompatible, water-soluble, polycationic two-photon absorbing anthracenyl derivative (Ant-PIm) specifically designed for biorelated applications. Detailed insights into the Ant-PIm-DNA binding interaction are provided by using several spectroscopic approaches, including UV-vis absorption, circular dichroism (CD), Fourier-transform infrared spectroscopy (FTIR), steady-state, and time-resolved fluorescence techniques. Absorption and fluorescence quantitative data analysis show a strong Ant-PIm-duplex interaction with binding constants of K = 4.7 ± 0.2 × 10 M, 7.1 ± 0.3 × 10 M, and 1.0 ± 0.1 × 10 M at 298, 304, and 310 K, respectively. Spectral changes observed upon DNA binding provide evidence for a complex formation with off-on fluorescence pattern, which can be related to two consecutive binding equilibria. Results of DNA binders displacement and iodide quenching experimental assays unambiguously point to the groove binding mode of Ant-PIm to the DNA-helicate. Thermodynamic and chemical denaturation studies suggest that long-range interactions of hydrophobic nature regulate the association of Ant-PIm with the biopolymer. The ionic strength dependence of the binding constant shows that electrostatic component has an important contribution to the overall Gibbs free energy. FTIR and CD data provide evidence of partial modification of the B-DNA secondary structure, while the increase in the melting temperature clearly indicates the enhancement of the thermal stability of the duplex. Furthermore, the two-photon absorption cross section spectrum determined using the two-photon excited fluorescence (TPEF) technique shows a strong 2PA maximum at 820 nm with a σ > 800 GM, which emphasizes the advantageous combination of biological and optical properties possessed by this positively charged bioprobe.
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http://dx.doi.org/10.1021/acs.biomac.6b01113DOI Listing
November 2016

Carbazole-Substituted Iridium Complex as a Solid State Emitter for Two-Photon Intravital Imaging.

Inorg Chem 2016 Oct 12;55(19):9586-9595. Epub 2016 Sep 12.

Laboratoire de Chimie, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard, Université de Lyon , F69342 Lyon, France.

A tris-cyclometalated iridium complex that bears two ligands functionalized by peripheral carbazole groups combines an intense solid state emission and a significant two-photon absorption cross section in the near-infrared. After incorporation into a physiological micellar suspension, it can be used for the intravital two-photon fluorescence microscopy of cerebral vasculature.
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http://dx.doi.org/10.1021/acs.inorgchem.6b01253DOI Listing
October 2016

Theoretical and Experimental Study on Boron β-Diketonate Complexes with Intense Two-Photon-Induced Fluorescence in Solution and in the Solid State.

Chemphyschem 2016 Jul 18;17(14):2128-36. Epub 2016 Apr 18.

Laboratoire de Chimie UMR CNRS 5182, Ecole Normale Supérieure de Lyon/Université de Lyon, 46, Allée d'Italie, 69007, Lyon, France.

Three boron diketonate chromophores with extended π-conjugated backbone were prepared and their spectroscopic features were investigated through a combined theoretical/experimental study. It was shown that these complexes, which undergo very large electronic reorganization upon photoexcitation, combine large two-photon absorption cross section with an emission energy and quantum efficiency in solution that is strongly dependent on solvent polarity. The strong positive influence of boron complexation on the magnitude of the two-photon absorption was clearly established, and it was shown that the two-photon absorption properties were dominated by the quadrupolar term. For one of the synthesized compounds, intense one- and two-photon-induced solid-state emission (fluorescence quantum yield of 0.65 with maximum wavelength of 610 nm) was obtained as a result of antiparallel J-aggregate crystal packing.
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http://dx.doi.org/10.1002/cphc.201600178DOI Listing
July 2016

Interactions of a biocompatible water-soluble anthracenyl polymer derivative with double-stranded DNA.

Phys Chem Chem Phys 2015 Nov;17(45):30318-27

Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland.

We have studied the interaction of a polymeric water soluble anthracenyl derivative () with salmon testes DNA. The results from UV-Vis, fluorescence, Fourier transform infrared (FT-IR) and circular dichroism spectroscopies indicate that the groove binding process regulates the interaction between and DNA. The binding constants, calculated by absorption spectroscopy at 298, 304 and 310 K, were equal to 3.2 × 10(5) M(-1), 4.7 × 10(5) M(-1), and 6.6 × 10(5) M(-1) respectively, proving a relatively high affinity of for salmon testes DNA. Results of Hoechst 33258 displacement assays strongly support the groove binding mode of to DNA. The association stoichiometry of the :DNA adduct was found to be 1 for every 5 base pairs. FT-IR spectra, recorded at different /DNA molar ratios, indicate the involvement of the phosphate groups and adenine and thymine DNA bases in the association process. Thermodynamic results suggest that hydrophobic forces regulate the binding of with DNA without excluding some extent of involvement of van der Waals forces and hydrogen bonding arising due to surface binding between the hydrophilic polymeric arms of the ligand and the functional groups positioned on the edge of the groove. The resulting composite biomaterial could constitute a valuable candidate for future biological and/or photonic applications.
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http://dx.doi.org/10.1039/c5cp05381aDOI Listing
November 2015

Mediating gel formation from structurally controlled poly(electrolytes) through multiple "head-to-body" electrostatic interactions.

Macromol Rapid Commun 2015 Jan 29;36(1):55-9. Epub 2014 Oct 29.

Laboratoire de Chimie UMR CNRS 5182, Ecole Normale Supérieure de Lyon/Université Claude Bernard Lyon1/Université de Lyon, 46 Allée d'Italie, 69007, Lyon, France.

Tuning the chain-end functionality of a short-chain cationic homopolymer, owing to the nature of the initiator used in the atom transfer radical polymerization (ATRP) polymerization step, can be used to mediate the formation of a gel of this poly(electrolyte) in water. While a neutral end group gives a solution of low viscosity, a highly homogeneous gel is obtained with a phosphonate anionic moiety, as characterized by rheometry and diffusion nuclear magnetic resonance (NMR). This novel type of supramolecular control over poly(electrolytic) gel formation could find potential use in a variety of applications in the field of electro-active materials.
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http://dx.doi.org/10.1002/marc.201400478DOI Listing
January 2015

Expanding the polymethine paradigm: evidence for the contribution of a bis-dipolar electronic structure.

J Phys Chem A 2014 Jun 2;118(23):4038-47. Epub 2014 Jun 2.

Laboratoire de Chimie, UMR 5182, CNRS, ENS Lyon, Université Lyon 1, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.

Although it has been reported in a few instances that the spectroscopic properties of cyanine dyes were strongly dependent on the nature of the chemical substitution of their central carbon atom, there has not been to date any systematic study specifically aimed at rationalizing this behavior. In this article, such a systematic study is carried out on an extended family of 17 polymethine dyes carrying different substituents on their central carbon, some of those being specifically synthesized for this study, some of those similar to previously reported compounds, for the sake of comparison. Their absorption properties, which spread over the whole visible to near-infrared spectral range, are seen to be dramatically dependent on the electron-donating character of this central substituent. By correlating this behavior to NMR spectroscopy and (vibronic) TD-DFT calculations, we show that it results from a profound modification of the ground state electronic configuration, namely, a progressive localization of the cationic charge on the central carbon as the electron-donating nature of the central substituent is increased.
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http://dx.doi.org/10.1021/jp501358qDOI Listing
June 2014

Remarkable effect of iridium cyclometalation on the nonlinear absorption properties of a quadrupolar imine ligand.

Inorg Chem 2013 Oct 10;52(19):10705-7. Epub 2013 Sep 10.

CNRS UMR-5182, Université Claude Bernard , École Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon, France.

A new type of dinuclear iridium complex, based on a quadrupolar Schiff base ligand, is synthesized and its structure fully characterized. Its linear and nonlinear spectroscopic properties are investigated, evidencing a strong contribution of the metal-to-ligand transitions not only to the linear absorption but also to the two- and three-photon absorption properties.
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http://dx.doi.org/10.1021/ic4012313DOI Listing
October 2013

Nanocarriers with ultrahigh chromophore loading for fluorescence bio-imaging and photodynamic therapy.

Biomaterials 2013 Nov 31;34(33):8344-51. Epub 2013 Jul 31.

Laboratoire de Chimie UMR 5182, Ecole Normale Supérieure de Lyon, CNRS, université Lyon 1, 46, allée d'Italie, Lyon cedex 07 F-69364, France.

We describe the design of original nanocarriers that allows for ultrahigh chromophore loading while maintaining the photo-activity of each individual molecule. They consist in shells of charged biocompatible polymers grafted on gold nanospheres. The self-organization of extended polymer chains results from repulsive charges and steric interactions that are optimized by tuning the surface curvature of nanoparticles. This type of nano-scaffolds can be used as light-activated theranostic agents for fluorescence imaging and photodynamic therapy. We demonstrate that, labeled with a fluorescent photosensitizer, it can localize therapeutic molecules before triggering the cell death of B16-F10 melanoma with an efficiency that is similar to the efficiency of the polymer conjugate alone, and with the advantage of extremely high local loading of photosensitizers (object concentration in the picomolar range).
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http://dx.doi.org/10.1016/j.biomaterials.2013.07.032DOI Listing
November 2013

Influence of bromine substitution pattern on the singlet oxygen generation efficiency of two-photon absorbing chromophores.

Org Biomol Chem 2012 Aug 29;10(31):6275-8. Epub 2012 Jun 29.

Laboratoire de Chimie CNRS UMR 5182, Université Lyon 1, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France.

A molecular engineering strategy based on rational variations of the bromine substitution pattern in two-photon absorbing singlet oxygen sensitizers allows studying the relations that exist between the positioning of an inter-system crossing promoter on the charge-transfer chromophore and its ability to generate singlet oxygen.
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http://dx.doi.org/10.1039/c2ob25536gDOI Listing
August 2012

An improved singlet oxygen sensitizer with two-photon absorption and emission in the biological transparency window as a result of ground state symmetry-breaking.

Chem Commun (Camb) 2012 Feb 19;48(11):1689-91. Epub 2011 Dec 19.

CNRSUMR 5182, Université Lyon 1, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France.

A chromophore featuring a diyne bridge that connects two dibromobenzene moieties shows a much improved two-photon singlet oxygen generation ability in the biological transparency window compared to a related and relevant literature benchmark, as a result of a distorted ground state.
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http://dx.doi.org/10.1039/c2cc15904jDOI Listing
February 2012
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