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Sophie Brasselet

Bio: Sophie Brasselet is an academic researcher from Aix-Marseille University. The author has contributed to research in topics: Second-harmonic generation & Microscopy. The author has an hindex of 43, co-authored 214 publications receiving 5714 citations. Previous affiliations of Sophie Brasselet include Centre national de la recherche scientifique & École centrale de Marseille.


Papers
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TL;DR: In this article, boron trihalide-induced cyclotrimerization of adequately substituted derivatives of phthalonitrile in 1,2-dicyanobenzene derivatives has been made taking into account the high reactivity of the Lewis acid BCl3 toward many functional groups.
Abstract: Novel boron(III) subphthalocyanines (SubPcs) soluble in organic solvents containing a variety of donor and acceptor substituent groups have been synthesized by boron trihalide-induced cyclotrimerization of adequately substituted derivatives of phthalonitrile in 1-chloronaphthalene. The choice of the substituents on the 1,2-dicyanobenzene derivatives has been made taking into account the high reactivity of the Lewis acid BCl3 toward many functional groups. Considering this limitation, we set out to synthesize phthalodinitriles equipped with iodo, nitro, alkyl- or arylthio, alkyl- or arylsulfonyl groups that are sufficiently stable under the required reaction conditions and also provide an easily accessible set of acceptor/donor substituents. The quadratic and cubic hyperpolarizabilities of these compounds as well as their linear optical and electrochemical properties have been measured by several techniques, including EFISH (at two wavelengths), HRS, and THG, steady-state and time-resolved absorption and f...

264 citations

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TL;DR: In this article, a general class of multipolar molecules is introduced in the context of quadratic nonlinear optics by way of extension of the more specific cases of dipolar and octupolar molecules, and experiments in both harmonic light scattering in solution and optical poling (in Disperse Red 1-methyl methacrylate thin films) are analyzed in light of this model.
Abstract: A general class of multipolar molecules is introduced in the context of quadratic nonlinear optics by way of extension of the more specific cases of dipolar and octupolar molecules. An adequate irreducible tensor formalism permits us to define rotationally invariant molecular features that couple to corresponding field tensor components, thereby enabling us to account for a variety of coherent and noncoherent processes such as harmonic light (hyper-Rayleigh) scattering, coherent second-harmonic generation in electrically poled media, and the recently proposed optical poling scheme. Experiments in both harmonic light scattering in solution (for some multipolar molecules) and optical poling (in Disperse Red 1–methyl methacrylate thin films) are analyzed in light of this model. A general tensorial permutation lemma of broad validity allows nonlinear light–matter interactions to be condensed in a statistical medium in compact rotationally invariant expressions: The main tensorial symmetry features for both molecular susceptibility and read–write field polarization tensors that jointly drive these interactions are clearly revealed.

250 citations

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TL;DR: This study finds no strong evidence for significant confinement of either GPI-linked or native I-E(k) in the plasma membrane of CHO cells, and analyses show that motion is predominantly Brownian.

244 citations

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TL;DR: In vitro reconstitution assays show that septins alone bundle actin filaments into rings, accounting for the defects in actin ring formation in septin mutants, and highlight unique functions of septin in the organization of contractile actomyosin rings.
Abstract: Animal cell cytokinesis requires a contractile ring of crosslinked actin filaments and myosin motors. How contractile rings form and are stabilized in dividing cells remains unclear. We address this problem by focusing on septins, highly conserved proteins in eukaryotes whose precise contribution to cytokinesis remains elusive. We use the cleavage of the Drosophila melanogaster embryo as a model system, where contractile actin rings drive constriction of invaginating membranes to produce an epithelium in a manner akin to cell division. In vivo functional studies show that septins are required for generating curved and tightly packed actin filament networks. In vitro reconstitution assays show that septins alone bundle actin filaments into rings, accounting for the defects in actin ring formation in septin mutants. The bundling and bending activities are conserved for human septins, and highlight unique functions of septins in the organization of contractile actomyosin rings.

196 citations

Journal ArticleDOI
TL;DR: In this article, a series of 2,4,6-triaryloxy-1,3,5-triazines, 1−6, are reported to consistently form quasi-trigonal or trigonal networks that are two-dimensionalally non-centrosymmetric.
Abstract: The principles of crystal engineering have been used to design a family of structures with potential as octupolar nonlinear optical (NLO) materials. The major aim in such an exercise, a carry-over of molecular symmetry into the crystal, is possible with a retrosynthetic approach. An appropriate choice of precursor trigonal molecules leads from the concept of the dimeric Piedfort unit. The crystal structures and NLO properties of a series of 2,4,6-triaryloxy-1,3,5-triazines, 1−6, are reported. These compounds consistently form quasi-trigonal or trigonal networks that are two-dimensionally noncentrosymmetric. Substitutional variations on the phenyl moieties that were expected to maintain or to perturb this trigonal network have been explored. Molecular nonlinearities have been measured by Harmonic Light Scattering (HLS) experiments. Among the compounds studied, 2,4,6-triphenoxy-1,3,5-triazine, 1 adopts a noncentrosymmetric crystal structure with a measurable SHG powder signal. All these crystal structures a...

195 citations


Cited by
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Journal ArticleDOI
TL;DR: A new method for fluorescence imaging has been developed that can obtain spatial distributions of large numbers of fluorescent molecules on length scales shorter than the classical diffraction limit, and suggests a means to address a significant number of biological questions that had previously been limited by microscope resolution.

3,437 citations

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TL;DR: This work presents the stepwise evolution of DsRed to a dimer and then either to a genetic fusion of two copies of the protein, i.e., a tandem dimer, or to a true monomer designated mRFP1 (monomeric red fluorescent protein).
Abstract: All coelenterate fluorescent proteins cloned to date display some form of quaternary structure, including the weak tendency of Aequorea green fluorescent protein (GFP) to dimerize, the obligate dimerization of Renilla GFP, and the obligate tetramerization of the red fluorescent protein from Discosoma (DsRed). Although the weak dimerization of Aequorea GFP has not impeded its acceptance as an indispensable tool of cell biology, the obligate tetramerization of DsRed has greatly hindered its use as a genetically encoded fusion tag. We present here the stepwise evolution of DsRed to a dimer and then either to a genetic fusion of two copies of the protein, i.e., a tandem dimer, or to a true monomer designated mRFP1 (monomeric red fluorescent protein). Each subunit interface was disrupted by insertion of arginines, which initially crippled the resulting protein, but red fluorescence could be rescued by random and directed mutagenesis totaling 17 substitutions in the dimer and 33 in mRFP1. Fusions of the gap junction protein connexin43 to mRFP1 formed fully functional junctions, whereas analogous fusions to the tetramer and dimer failed. Although mRFP1 has somewhat lower extinction coefficient, quantum yield, and photostability than DsRed, mRFP1 matures >10 times faster, so that it shows similar brightness in living cells. In addition, the excitation and emission peaks of mRFP1, 584 and 607 nm, are ≈25 nm red-shifted from DsRed, which should confer greater tissue penetration and spectral separation from autofluorescence and other fluorescent proteins.

2,451 citations

Journal ArticleDOI
TL;DR: In this article, the authors propose a vectorial chemistry approach for the generation of new generations of hybrid materials, which will open a land of promising applications in many areas: optics, electronics, ionics, mechanics, energy, environment, biology, medicine for example as membranes and separation devices, functional smart coatings, fuel and solar cells, catalysts, sensors, etc.
Abstract: Organic–inorganic hybrid materials do not represent only a creative alternative to design new materials and compounds for academic research, but their improved or unusual features allow the development of innovative industrial applications. Nowadays, most of the hybrid materials that have already entered the market are synthesised and processed by using conventional soft chemistry based routes developed in the eighties. These processes are based on: a) the copolymerisation of functional organosilanes, macromonomers, and metal alkoxides, b) the encapsulation of organic components within sol–gel derived silica or metallic oxides, c) the organic functionalisation of nanofillers, nanoclays or other compounds with lamellar structures, etc. The chemical strategies (self-assembly, nanobuilding block approaches, hybrid MOF (Metal Organic Frameworks), integrative synthesis, coupled processes, bio-inspired strategies, etc.) offered nowadays by academic research allow, through an intelligent tuned coding, the development of a new vectorial chemistry, able to direct the assembling of a large variety of structurally well defined nano-objects into complex hybrid architectures hierarchically organised in terms of structure and functions. Looking to the future, there is no doubt that these new generations of hybrid materials, born from the very fruitful activities in this research field, will open a land of promising applications in many areas: optics, electronics, ionics, mechanics, energy, environment, biology, medicine for example as membranes and separation devices, functional smart coatings, fuel and solar cells, catalysts, sensors, etc.

2,321 citations

Journal ArticleDOI
TL;DR: A practical guide to using smFRET, focusing on the study of immobilized molecules that allow measurements of single-molecule reaction trajectories from 1 ms to many minutes, is provided.
Abstract: Single-molecule fluorescence resonance energy transfer (smFRET) is one of the most general and adaptable single-molecule techniques. Despite the explosive growth in the application of smFRET to answer biological questions in the last decade, the technique has been practiced mostly by biophysicists. We provide a practical guide to using smFRET, focusing on the study of immobilized molecules that allow measurements of single-molecule reaction trajectories from 1 ms to many minutes. We discuss issues a biologist must consider to conduct successful smFRET experiments, including experimental design, sample preparation, single-molecule detection and data analysis. We also describe how a smFRET-capable instrument can be built at a reasonable cost with off-the-shelf components and operated reliably using well-established protocols and freely available software.

1,929 citations

Journal ArticleDOI
14 Nov 2003-Cell
TL;DR: There has been considerable recent interest in the possibility that the plasma membrane contains lipid "rafts," microdomains enriched in cholesterol and sphingolipids, and it seems that a definitive proof of raft existence has yet to be obtained.

1,415 citations