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The advent of chemical tools for cellular imaging—from organic dyes to green fluorescent proteins—has revolutionized the fields
of molecular biology and biochemistry. Lanthanide-based probes are a new player in this area, as the last decade has seen
the emergence of the first responsive luminescent lanthanide probes specifically intended for imaging cellular processes.
The potential of these probes is still undervalued by the scientific community. Indeed, this class of probes offers several
advantages over organic dyes and fluorescent proteins. Their very long luminescence lifetimes enable quantitative spatial
determination of the intracellular concentration of an analyte through time-gating measurements. Their emission bands are
very narrow and do not overlap, enabling the simultaneous use of multiple lanthanide probes to quantitatively detect several
analytes without cross-interference. Herein we describe the principles behind the development of this class of probes. Sensors
for a desired analyte can be designed by rationally manipulating the parameters that influence the luminescence of lanthanide
complexes. We will discuss sensors based on varying the number of inner-sphere water molecules, the distance separating the
antenna from the lanthanide ion, the energies of excited states of the antenna, and PeT switches.
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Valérie C. PierreEmail: |
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Aurore Olivier Jean-Marie Raquez Philippe Dubois Pascal Damman 《European Polymer Journal》2011,(1):31-39
This paper is the first report about the morphology of semi-crystalline poly(ε-caprolactone) (PCL) brushes studied by Atomic Force Microscopy (AFM) in tapping mode. This represents a convenient way to observe how the growth of a polymer proceeds from a thiol monolayer on gold substrate in terms of grafting density and thiol monolayer stability. The synthesis of semi-crystalline PCL brushes was carried out by Ring-Opening Polymerization (ROP) of ε-caprolactone (ε-CL) from hydroxyl end-group of thiol monolayer on gold surface as catalyzed with tin octoate (Sn(Oct)2) at 50 °C. Addition of a sacrificial initiator was also attempted in order to get a finer control over PCL crystals. For a sake of comparison, triazabicyclo[4.4.0]dec-5-ene (TBD) was also investigated as another ROP catalyst active at ambient temperature. The composition and the morphology of resulting semi-crystalline PCL brushes were characterized using X-ray Photoelectron Spectroscopy (XPS) and AFM. In the case of Sn(Oct)2-promoted ROP of CL with or without free (sacrificial) initiator (i.e., benzyl alcohol), different types of morphologies were observed on the gold substrate, due to the thermal instability of thiol-gold bond under the experimental conditions. When TBD was used at ambient temperature, a regular and homogeneous crystalline morphology, i.e., compact PCL crystals, could be observed. 相似文献
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Dr. Aurore Thibon Véronique Jollet Dr. Caroline Ribal Dr. Katell Sénéchal‐David Laurianne Billon Dr. Alexander B. Sorokin Prof. Frédéric Banse 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(9):2715-2724
Ferric–hydroperoxo complexes have been identified as intermediates in the catalytic cycle of biological oxidants, but their role as key oxidants is still a matter of debate. Among the numerous synthetic low‐spin FeIII(OOH) complexes characterized to date, [(L52)Fe(OOH)]2+ is the only one that has been isolated in the solid state at low temperature, which has provided a unique opportunity for inspecting its oxidizing properties under single‐turnover conditions. In this report we show that [(L52)Fe(OOH)]2+ decays in the presence of aromatic substrates, such as anisole and benzene in acetonitrile, with first‐order kinetics. In addition, the phenol products are formed from the aromatic substrates with similar first‐order rate constants. Combining the kinetic data obtained at different temperatures and under different single‐turnover experimental conditions with experiments performed under catalytic conditions by using the substrate [1,3,5‐D3]benzene, which showed normal kinetic isotope effects (KIE>1) and a notable hydride shift (NIH shift), has allowed us to clarify the role played by FeIII(OOH) in aromatic oxidation. Several lines of experimental evidence in support of the previously postulated mechanism for the formation of two caged FeIV(O) and OH . species from the FeIII(OOH) complex have been obtained for the first time. After homolytic O? O cleavage, a caged pair of oxidants [FeIVO+HO . ] is generated that act in unison to hydroxylate the aromatic ring: HO . attacks the ring to give a hydroxycyclohexadienyl radical, which is further oxidized by FeIVO to give a cationic intermediate that gives rise to a NIH shift upon ketonization before the final re‐aromatization step. Spin‐trapping experiments in the presence of 5,5‐dimethyl‐1‐pyrroline N‐oxide and GC‐MS analyses of the intermediate products further support the proposed mechanism. 相似文献
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Dr. Erhan Deniz Noufal Kandoth Dr. Aurore Fraix Dr. Venera Cardile Dr. Adriana C. E. Graziano Dr. Debora Lo Furno Dr. Ruxandra Gref Prof. Françisco M. Raymo Prof. Salvatore Sortino 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(49):15782-15787
A viable strategy to encapsulate a fluorophore/photochrome dyad and a nitric oxide photodonor within supramolecular assemblies of a cyclodextrin‐based polymer in water was developed. The two photoresponsive guests do not interact with each other within their supramolecular container and can be operated in parallel under optical control. Specifically, the dyad permits the reversible switching of fluorescence on a microsecond timescale for hundreds of cycles, and the photodonor enables the irreversible release of nitric oxide. Furthermore, these supramolecular assemblies cross the membrane of human melanoma cancer cells and transport their cargo in the cytosol. The fluorescence of one component allows the visualization of the labeled cells, and its switchable character could, in principle, be used to acquire super‐resolution images, while the release of nitric oxide from the other induces significant cell mortality. Thus, our design logic for the construction of biocompatible nanoparticles with dual functionality might evolve into the realization of valuable photoresponsive probes for imaging and therapeutic applications. 相似文献
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Noufal Kandoth Milo Malanga Dr. Aurore Fraix Dr. László Jicsinszky Dr. Éva Fenyvesi Tiziana Parisi Ivana Colao Dr. Maria Teresa Sciortino Prof. Salvatore Sortino 《化学:亚洲杂志》2012,7(12):2888-2894
Herein we report the design, preparation, and properties of a supramolecular system based on a tailored nitric oxide (NO) photodonor and a rhodamine‐labeled β‐cyclodextrin conjugate. The combination of spectroscopic and photochemical experiments shows the absence of significant interchromophoric interactions between the host and the guest in the excited states. As a result, the complex is able to release NO under the exclusive control of visible light, as unambiguously demonstrated by direct detection of this transient species through an amperometric technique, and exhibits the typical red fluorescence of the rhodamine appendage. The supramolecular complex effectively internalizes in HeLa cancer cells as proven by fluorescence microscopy, shows a satisfactory biocompatibility in the dark, and induces about 50 % of cell mortality upon irradiation with visible light. The convergence of all these properties in one single complex makes the present host–guest ensemble an appealing candidate for further delevopment of photoactivatable nanoscaled systems addressed to photostimulated NO‐based therapy. 相似文献
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Thibon A Jollet V Ribal C Sénéchal-David K Billon L Sorokin AB Banse F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(9):2715-2724
Ferric-hydroperoxo complexes have been identified as intermediates in the catalytic cycle of biological oxidants, but their role as key oxidants is still a matter of debate. Among the numerous synthetic low-spin Fe(III)(OOH) complexes characterized to date, [(L(5)(2))Fe(OOH)](2+) is the only one that has been isolated in the solid state at low temperature, which has provided a unique opportunity for inspecting its oxidizing properties under single-turnover conditions. In this report we show that [(L(5)(2))Fe(OOH)](2+) decays in the presence of aromatic substrates, such as anisole and benzene in acetonitrile, with first-order kinetics. In addition, the phenol products are formed from the aromatic substrates with similar first-order rate constants. Combining the kinetic data obtained at different temperatures and under different single-turnover experimental conditions with experiments performed under catalytic conditions by using the substrate [1,3,5-D(3)]benzene, which showed normal kinetic isotope effects (KIE>1) and a notable hydride shift (NIH shift), has allowed us to clarify the role played by Fe(III)(OOH) in aromatic oxidation. Several lines of experimental evidence in support of the previously postulated mechanism for the formation of two caged Fe(IV)(O) and OH(·) species from the Fe(III)(OOH) complex have been obtained for the first time. After homolytic O-O cleavage, a caged pair of oxidants [Fe(IV)O+HO(·)] is generated that act in unison to hydroxylate the aromatic ring: HO(·) attacks the ring to give a hydroxycyclohexadienyl radical, which is further oxidized by Fe(IV)O to give a cationic intermediate that gives rise to a NIH shift upon ketonization before the final re-aromatization step. Spin-trapping experiments in the presence of 5,5-dimethyl-1-pyrroline N-oxide and GC-MS analyses of the intermediate products further support the proposed mechanism. 相似文献
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Lanoë PH Gallavardin T Dupin A Maury O Baldeck PL Lindgren M Monnereau C Andraud C 《Organic & biomolecular chemistry》2012,10(31):6275-6278
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. 相似文献