ORCID Profile
0000-0001-9222-3866
Current Organisation
École Polytechnique Fédérale de Lausanne
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Publisher: Wiley
Date: 11-02-2008
Abstract: The homoditopic ligand 6,6'-[methylenebis(1-methyl-1H-benzimidazole-5,2-diyl)]bis(4-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}pyridine-2-carboxylic acid) (H(2)L(C2)) has been tailored to self-assemble with lanthanide ions (Ln(III)), which results in the formation of neutral bimetallic helicates with the overall composition [Ln(2)(L(C2))(3)] and also provides a versatile platform for further derivatization. The grafting of poly(oxyethylene) groups onto the pyridine units ensures water solubility, while maintaining sizeable thermodynamic stability and adequate antenna effects for the excitation of both visible- and NIR-emitting Ln(III) ions. The conditional stability constants (log beta(23)) are close to 25 at physiological pH and under stoichiometric conditions. The ligand triplet state features adequate energy (0-phonon transition at approximately 21 900 cm(-1)) to sensitize the luminescence of Eu(III) (Q=21 %) and Tb(III) (11 %) in aerated water at pH 7.4. The emission of several other VIS- and NIR-emitting ions, such as Sm(III) (Q=0.38 %) or Yb(III) (0.15 %), for which in cellulo luminescence is evidenced for the first time, is also sensitized. The Eu(III) emission spectrum arises from a main species with pseudo-D(3) symmetry and without coordinated water. The cell viability of several cancerous cell lines (MCF-7, HeLa, Jurkat and 5D10) is unaffected if incubated with up to 500 microM [Eu(2)(L(C2))(3)] during 24 h. Bright Eu(III) emission is seen for incubation concentrations above 10 microM and after a 15-minute loading time similar images are obtained with Tb(III) and Sm(III). The helicates probably permeate into the cytoplasm of HeLa cells by endocytosis. The described luminescent helical stains are robust chemical species which remain undissociated in the cell medium and in presence of other complexing agents, such as edta, dtpa, citrate or L-ascorbate. Their derivatization, which would open the way to the sensing of targeted in cellulo phenomena, is currently under investigation.
Publisher: Wiley
Date: 15-05-2007
Publisher: Elsevier BV
Date: 06-2007
Publisher: Wiley
Date: 16-11-2007
Abstract: The homoditopic ligand H2LC3 has been designed to form neutral triple-stranded bimetallic helicates of overall composition [Ln2(LC3)3]. The grafting of the polyoxyethylene fragments ensures water solubility and also favors cell penetration while being amenable to further derivatization. The ligand pKa values have been determined by spectrophotometric titration and range from 3.5 (sum of the first two) to 10.3. The thermodynamic stability of the helicates is large at physiological pH (logbeta23 in the range 22-23). The ligand triplet state has an adequate energy (0-phonon transition at approximately 20,800 cm(-1)) for sensitizing the luminescence of EuIII (Q=11%). Analysis of the EuIII emission spectrum points to an overall pseudo D3 symmetry for the metal environment. No significant effect of [Eu2(LC3)3] is observed on the viability of several cancerous cell lines (MCF-7, HeLa, Jurkat, and 5D10). The cell imaging properties of the EuIII helicate are demonstrated for the HeLa cell line by luminescence microscopy. Bright EuIII emission is seen for helicate concentration>50 microM and after 20-30 min loading time. The helicate stains the cytoplasm and the permeation mechanism is likely to be endocytosis.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0NJ00440E
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B800516H
Publisher: Royal Society of Chemistry (RSC)
Date: 22-01-2003
DOI: 10.1039/B211267C
Abstract: The synthesis of 4-substituted dipicolinic acid derivatives requiring palladium catalysis is described. A keto-enol equilibrium has been observed, depending on the nature of the 2,6-position substituents.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1SC05517H
Abstract: The first observed luminescence emission spectra of Pr( iv ) complexes are assigned to a ligand-based emission. Binding of the triphenylsiloxide ligand to the Pr( iv ) ion leads to an unprecedented large red shift of its triplet state.
Publisher: Elsevier
Date: 2014
Publisher: American Chemical Society (ACS)
Date: 04-02-2010
DOI: 10.1021/JP9090206
Abstract: Multiphoton excited luminescent properties of water-soluble Eu(III) and Tb(III) complexes with derivatives of dipicolinic acid functionalized with a polyoxyethylene pendant arm and terminal groups, [Eu(L(OMe))(3)](3-), [Eu(L(NH2))(3)](3-), and [Tb(L(OH))(3)](3-), as well as of binuclear helicates with overall composition [Ln(2)(L(CX))(3)] (X = 2, 5) are investigated. Characteristic emission from the (5)D(0) and (5)D(4) excited levels of Eu(III) and Tb(III), respectively, upon approximately 800 nm excitation results from three-photon absorption (3PA) for [Eu(L(OMe))(3)](3-), [Eu(L(NH2))(3)](3-), [Tb(L(OH))(3)](3-), and [Ln(2)(L(C2))(3)], while luminescence from [Eu(2)(L(C5))(3)] is induced by two-photon absorption (2PA) owing to its 1PA spectrum extending further into the visible. The 3PA cross sections have been determined and are the first ones reported for lanthanide complexes: (i) those of Eu(III) and Tb(III) bimetallic helicates [Ln(2)(L(C2))(3)] are 20 times larger compared to the corresponding values for tris(dipicolinates) (ii) derivatization of dipicolinic acid for Tb(III) complexes has almost no influence on the 3PA cross section however, for Eu(III) complexes a approximately 2 times decrease is observed. The feasibility of [Eu(2)(L(C5))(3)] as multiphoton luminescence bioprobe is demonstrated by two-photon scanning microscopy imaging experiments on HeLa cells incubated with this bimetallic helicate.
Publisher: Wiley
Date: 05-2008
Abstract: As the need for targeting luminescent biolabels increases, for mapping selected analytes, imaging of cells and organs, and tracking in cellulo processes, lanthanide bimetallic helicates are emerging as versatile bioprobes. The wrapping of three ligand strands around two metallic centers by self-assembly affords robust molecular edifices with tunable chemical and photophysical properties. In addition, heterometallic helical chelates can be assembled leading to bioprobes with inherent chiral properties. In this paper, we review the literature demonstrating that neutral [Ln(2)(L(CX))(3)] (x=1-3) helicates represent a viable alternative to existing chelating agents for bio-analyses, while featuring specific enhanced properties. These bimetallic chelates self-assemble in water, and at physiological pH the 2:3 (Ln:L(CX)) complex is by far the dominant species, conditional stability constants logbeta(23) being in the range 23-30. The metal ions are 9-coordinate and lie in sites with slightly distorted D(3) symmetry. Efficient protection from water interaction by the tightly wrapped ligand strands results in sizeable photophysical properties, with quantum yields up to 24% for Eu(III) and 11% for Tb(III), while the luminescence of several other visible and/or near-infrared emitting Ln(III) ions is also sensitized. Noncytotoxicity for all the helicates is established for several living cell lines including HeLa, HaCat, MCF-7, 5D10, and Jurkat. We present new data pertaining to the live cell imaging ability of [Eu(2)(L(C1))(3)] and compare the three systems with x=1-3 with respect to thermodynamic stability, photophysics, cell-permeation ability, and targeting capability for sensing in cellulo processes. Prospects of derivatization for characterizing specific biological interactions are discussed.
Publisher: American Chemical Society (ACS)
Date: 20-10-2004
DOI: 10.1021/IC049118X
Abstract: A series of four ligands based on a 5'-methyl-2,2'-bipyridyl framework substituted in the 6 position by a carboxylic acid, a phosphonic acid, a monoethyl ester phosphonic acid, or a diethyl ester phosphonic acid are described. The pK(a) values of all ligands and their assignments are determined by a combination of UV-vis absorption spectroscopy and (1)H and (31)P NMR spectroscopy. The ability of the tridentate ligands to form complexes with trivalent lanthanide cations (Ln = La, Nd, Eu, and Lu) in buffered water solutions (Tris-HCl, pH = 7.4) is studied by UV-vis absorption spectroscopy and (1)H NMR. While the two ester ligands display a weak coordination ability toward lanthanide cations, the acid ligands form stable complexes with 1:1, 1:2, and 1:3 Ln/L ratios. A weak selectivity is observed for the middle of the lanthanide series, and the complexes of the phosphonic acid derivative are up to 2 orders of magnitude more stable than those of the carboxylic acid ligand. Photophysical properties of the free phosphonic and carboxylic acid ligands and of their complexes with La, Eu, Gd, Tb, and Lu are investigated in buffered aqueous solutions both at room temperature and 77 K. An efficient ligand-to-metal energy transfer is observed for both the Eu and Tb complexes. Despite a relatively large energy gap between the ligand-centered (3)pipi* and the Eu((5)D(0)) or Tb((5)D(4)) emitting states, the metal-centered luminescence is well sensitized with quantum yields reaching up to 45.5 and 42.2% for the Tb 1:3 complexes with carboxylic and phosphonic acid ligands, respectively.
Publisher: American Chemical Society (ACS)
Date: 24-12-2005
DOI: 10.1021/IC0515249
Abstract: New polydentate ligands (e.g., Tsox and TsoxMe) have been synthesized to take advantage of the chelating effect of bidentate 8-hydroxyquinolinate subunits connected to a N,N,N',N'-tetraaminopropyl-1,2-ethylenediamine framework and with the aim of sensitizing the NIR luminescence of Nd(III) and Yb(III) ions. Ten pK(a)'s have been determined and the interaction between the ligands and Ln(III) ions in dilute aqueous solution has been probed both by potentiometric and spectrophotometric titrations. These studies have been mostly performed with the Eu(III) ion, which is in the middle of the lanthanide series, and extended to other ions (La(III), Er(III), Lu(IIII)). Stable complexes with Ln(III) ions are formed (pLn in the range of 14-16), the four chromophoric units being coordinated to the metal center, exploiting the entropic effect generated by the anchor. The monometallic complexes [Ln(H(2)L)](3)(-) exist as the major species at physiological pH regardless of the lanthanide used. Lifetime determinations of the Nd((4)F(3/2)) and Yb((2)F(5/2)) excited levels in both H(2)O and D(2)O at buffered pH point to the absence of water molecules bound in the inner coordination sphere of the Ln(III). Photophysical properties of the free ligands and of their lanthanide complexes have been investigated in buffered aqueous solutions both at room temperature and 77 K. The low-energy triplet state makes energy transfers from the ligand to the metal ions possible this leads to a sizable sensitization of the Nd(III)- or Yb(III)-centered luminescence ( = 0.02% and = 0.18%) for Tsox chelates. Methylation of the amide functions removes the quenching mechanism induced by the proximate N-H vibrations and increases both the lifetimes and quantum yields of the TsoxMe chelates ( = 0.04% and = 0.37%). In fact, TsoxMe yields one of the most luminescent Yb(III) compounds known in water, and this ligand appears to be suitable for the development of NIR probes for bioanalyses.
Publisher: Wiley
Date: 05-01-2009
Abstract: A series of homoditopic ligands H(2)L(CX) (X=4-6) has been designed to self-assemble with lanthanide ions (Ln(III)), resulting in neutral bimetallic helicates of overall composition [Ln(2)(L(CX))(3)] with the aim of testing the influence of substituents on the photophysical properties, particularly the excitation wavelength. The complex species are thermodynamically stable in water (log beta(23) in the range 26-28 at pH 7.4) and display a metal-ion environment with pseudo-D(3) symmetry and devoid of coordinated water molecules. The emission of Eu(III), Tb(III), and Yb(III) is sensitised to various extents, depending on the properties of the ligand donor levels. The best helicate is [Eu(2)(L(C5))(3)] with excitation maxima at 350 and 365 nm and a quantum yield of 9 %. The viability of cervix cancer HeLa cells is unaffected when incubated with up to 500 mum of the chelate during 24 h. The helicate permeates into the cells by endocytosis and locates into lysosomes, which co-localise with the endoplasmatic reticulum, as demonstrated by counterstaining experiments. The relatively long excitation wavelength allows easy recording of bright luminescent images on a confocal microscope (lambda(exc)=405 nm). The new lanthanide bioprobe remains undissociated in the cell medium, and is amenable to facile derivatisation. Examination of data for seven Eu(III) and Tb(III) bimetallic helicates point to shortcomings in the phenomenological rules of thumb between the energy gap DeltaE((3)pipi*-(5)D(J)) and the sensitisation efficiency of the ligands.
Publisher: American Chemical Society (ACS)
Date: 19-10-2009
DOI: 10.1021/IC901424W
Abstract: A series of hexadentate ditopic receptors incorporating benzimidazole moieties have been designed, which are fitted with phosphonic acid or phosphoethylester coordinating units. In addition, poly(oxyethylene) pendants have been introduced on the benzimidazole backbone of two ligands to increase water solubility. The ligands self-assemble with lanthanide ions under stoichiometric conditions, yielding triple-stranded homobimetallic helicates, as ascertained by mass spectrometry and UV-visible titrations. The helicates display large thermodynamic stability, for ex le, log beta(23) approximately 21-24 for all the Eu(III) complexes. Photophysical measurements reveal sensitization of the metal-centered luminescence in the europium and terbium complexes, which is modulated by the nature of the ligand. Hydration numbers determined by the lifetime method are essentially zero. The Eu((5)D(0)) lifetimes are long and reach values up to 3.2 ms, while quantum yields as high as 25% are obtained in water at pH 7.4. Back transfer limits the sensitization efficiency for Tb(III) luminescence, and both lifetimes and quantum yields are much smaller. The properties of the helicates are discussed with respect to those self-assembled from ligands bearing carboxylate coordinating units.
Publisher: American Chemical Society (ACS)
Date: 26-07-2008
DOI: 10.1021/IC800842F
Abstract: Derivatives of dipicolinic acid with a polyoxyethylene pendant arm at the pyridine 4-position have been functionalized for potential grafting with biological material. Four ligands with different terminal functions (alcohol, methoxy, phtalimide and amine) have been synthesized, which react with trivalent lanthanide ions Ln (III) to yield triple helical [Ln(L) 3] (3-) complexes, as shown by NMR and UV-vis titrations. The tris chelates display large thermodynamic stability with log beta 13 approximately 19-20 for all Eu (III) complexes for instance. Photophysical measurements reveal adequate sensitization of the metal-centered luminescence in the europium (eta sens = 33-72%) and terbium complexes, which is modulated by the nature of the terminal function. The lifetimes of the metal-centered excited states are long, up to 1.4 ms for [Eu(L) 3] (3-) and 1.6 ms for [Tb(L) 3] (3-) at room temperature, in line with hydration numbers essentially equal to zero. Quantum yields are as high as 29% for the [Eu( L ( NH2 )) 3] (3-) and 18% for the [Tb( L ( OH )) 3] (3-) tris chelates in water at physiological pH. These series of complexes demonstrate the extent of fine-tuning achievable for lanthanide luminescent probes and are simple models for investigating the effect of binding to biological molecules on the metal-centered luminescent properties.
Publisher: Wiley
Date: 07-2002
DOI: 10.1002/1522-2675(200207)85:7<1915::AID-HLCA1915>3.0.CO;2-N
Publisher: Informa UK Limited
Date: 31-12-2004
DOI: 10.1081/SL-120039700
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B614036J
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B416575F
Abstract: The novel hydroxyquinoline-containing tetrapodal ligand forms water soluble and stable chelates and is a good sensitizer of the NIR luminescence of its Nd(III) and Yb(III) complexes its easy synthesis opens the way for potential biomedical applications.
Publisher: Elsevier BV
Date: 04-2001
Publisher: Wiley
Date: 29-08-2006
Abstract: Highly selective separation of yttrium (and lanthanides) is of interest for the design of radiopharmaceuticals, and an efficient method based on the ion-imprinting concept is proposed here. The synthesis and structural, thermodynamic and photophysical characterization of complexes of trivalent yttrium and lanthanides with two new vinyl derivatives of dipicolinic acid, HL1 and L2, are described. The feasibility of using ion-imprinted resins for yttrium and lanthanide separation is demonstrated. The resins were obtained by copolymerization with styrene and inylbenzene and subsequent acid treatment to remove the metal ion. High-resolution Eu luminescence experiments revealed that the geometry of the complexation sites is well preserved in the imprinted polymers. The ion-imprinted polymer based on HL1 proved to be particularly well adapted for yttrium extraction, having a sizeable capacity (8.9+/-0.2 mg g(-1) resin) and a fast rate of extraction (t(1/2)=1.7 min). In addition, lighter and heavier lanthanide ions are separated. Finally, the resin displays high selectivity for yttrium and lanthanide cations against alkali and alkaline earth metals. For instance, in a typical experiment, 10 mg of yttrium was extracted from 5 g of milk ash s le by 2 g of the resin. The good separation properties displayed by the resin based on HL1 open interesting perspectives for the production of highly pure (90)Y and radiolanthanides for medical applications, and for trace analysis of these radiochemicals in food and in the environment.
Publisher: Swiss Chemical Society
Date: 26-05-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B811427G
Abstract: The cellular uptake mechanism and intracellular distribution of emissive lanthanide helicates have been elucidated by time-resolved luminescence microscopy (TRLM). The helicates are non-cytotoxic and taken up by normal (HaCat) and cancer (HeLa, MCF-7) cells by endocytosis and show a late endosomal-lysosomal cellular distribution. The lysosomes predominantly localize around the nucleus and co-localize with the endoplasmatic reticulum. The egress is slow and limited, around 30% after 24 h. The first bright luminescent images can be observed with an external concentration gradient of 5 microM of the Eu(III) helicate [Q = 0.21, tau = 2.43 ms], compared to >10 microM when using conventional luminescence microscopy. Furthermore, multiplex labeling could be achieved with the Tb(III) [Q = 0.11, tau = 0.65 ms], and Sm(III) [Q = 0.0038, tau = 0.030 ms] analogues.
Publisher: Swiss Chemical Society
Date: 2021
DOI: 10.2533/000942903777679587
Abstract: The goal of this three-year project is to establish a modular and interactive Internet website for the teaching of general chemistry to freshmen students enrolled in a life sciences university program (medicine, biology, possibly pharmacy). Students should become familiar with the basic chemistry concepts needed to understand important life processes and the whereabouts in day-to-day usage of chemical technologies. The idea behind the project, supported by four partner universities (Geneva, Lausanne, Neuchâtel, Fribourg), is to offer a flexible tool to students who have followed very different secondary education programs, some of them having not yet taken any science course. The project aims therefore at optimizing their basic science training during the first year of higher education. A system of online exercises and tests helps the students to assess their understanding of the matter. Video films of live experiments and computer simulations illustrate the main principles and phenomena described in the teaching program. Whenever possible, the teaching aims at an integrated vision of biosciences, as illustrated by some ex les using a problem-based approach. The site will offer bilingual (French, English), possibly trilingual (German), teaching and is intended to serve annually 1200–1300 students from the supporting universities.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B922124G
Abstract: The lanthanide binuclear helicate [Eu(2)(L(C2(CO(2)H)))(3)] is coupled to avidin to yield a luminescent bioconjugate EuB1 (Q = 9.3%, tau((5)D(0)) = 2.17 ms). MALDI/TOF mass spectrometry confirms the covalent binding of the Eu chelate and UV-visible spectroscopy allows one to determine a luminophore rotein ratio equal to 3.2. Bio-affinity assays involving the recognition of a mucin-like protein expressed on human breast cancer MCF-7 cells by a biotinylated monoclonal antibody 5D10 to which EuB1 is attached via avidin-biotin coupling demonstrate that (i) avidin activity is little affected by the coupling reaction and (ii) detection limits obtained by time-resolved (TR) luminescence with EuB1 and a commercial Eu-avidin conjugate are one order of magnitude lower than those of an organic conjugate (FITC-streptavidin). In the second part of the paper, conditions for growing MCF-7 cells in 100-200 microm wide microchannels engraved in PDMS are established we demonstrate that EuB1 can be applied as effectively on this lab-on-a-chip device for the detection of tumour-associated antigens as on MCF-7 cells grown in normal culture vials. In order to exploit the versatility of the ligand used for self-assembling [Ln(2)(L(C2(CO(2)H)))(3)] helicates, which sensitizes the luminescence of both Eu(III) and Tb(III) ions, a dual on-chip assay is proposed in which estrogen receptors (ERs) and human epidermal growth factor receptors (Her2/neu) can be simultaneously detected on human breast cancer tissue sections. The Ln helicates are coupled to two secondary antibodies: ERs are visualized by red-emitting EuB4 using goat anti-mouse IgG and Her2/neu receptors by green-emitting TbB5 using goat anti-rabbit IgG. The fact that the assay is more than 6 times faster and requires 5 times less reactants than conventional immunohistochemical assays provides essential advantages over conventional immunohistochemistry for future clinical biomarker detection.
Publisher: Elsevier BV
Date: 11-2010
Publisher: Swiss Chemical Society
Date: 28-04-2006
DOI: 10.2533/000942906777674895
Abstract: The metal ion imprinted concept has been used to imprint dipicolinic derivative coordination cages in styrene-based polymeric material. This resin displays very high selectivity for yttrium and lanthanides. Distribution coefficients determined for 88Y and 85Sr emphasize the possibility for the material to be used as chromatographic support for direct production of medical grade 90Y from a 90Sr source. Europium has been successfully extracted by the resin from a large volume of tap water. Thus the material could be used for radiation monitoring of nuclear power plants, particularly regarding the determination of radiolanthanides in the cooling system.
Publisher: The Royal Society
Date: 28-07-2013
Abstract: Lanthanide bioprobes and bioconjugates are ideal luminescent stains in view of their low propensity to photobleaching, sharp emission lines and long excited state lifetimes permitting time-resolved detection for enhanced sensitivity. In this paper, we expand our previous work which demonstrated that self-assembled dinuclear triple-stranded helicates [Ln 2 (L C2X ) 3 ] behave as excellent cell and tissue labels in immunocytochemical and immunohistochemical assays. The synthetic strategy of the hexadentate ditopic ligands incorporating dipicolinic acid, benzimidazole units and polyoxyethylene pendants is revisited in order to provide a more straightforward route and to give access to further functionalization of the polyoxyethylene arms by incorporating a terminal function X. Formation of the helicates [Ln 2 (L C2X ) 3 ] ( X =COOH, CH 2 OH, COEt, NH 2 , phthalimide) is ascertained by several experimental techniques and their stability tested against diethylenetriaminepentaacetate. Their photophysical properties (quantum yield, lifetime, radiative lifetime and sensitization efficiency) are presented and compared with those of the parent helicates [Ln 2 (L C2 ) 3 ]. Finally, the cellular uptake of five Eu III helicates is monitored by time-resolved luminescence microscopy and their localization in HeLa cells established by co-staining experiments.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B915893F
Abstract: Lanthanide complexes with two push-pull diketone derivatives as sensitizers have been developed as synthons for near-infrared emitting materials. The ligand substituents consist of a carbazole moiety with hole-transport properties and an aromatic or heteroaromatic unit. According to quantitative NMR analysis and complementary HPLC experiments, the diketones are predominantly in their enolic form in polar solvents such as THF and MeCN at room temperature. The preferred cis-enol form contributes strongly to the binding of lanthanide ions (Ln = Nd, Gd, Er). The resulting tris(diketonate) ternary complexes with terpyridine (Ln = Nd, Er) display sizeable near-IR emission with long luminescence lifetimes.
Publisher: Wiley
Date: 2006
Publisher: Wiley
Date: 18-10-2007
Abstract: A new macrocyclic ligand, L3, has been synthesised, based on the cyclen framework grafted with three phenacyl light-harvesting groups and a C5-alkyl chain bearing a carboxylic acid function as a potential linker for biological material. Acidity constants are determined by spectrophotometric titrations, as well as conditional stability constants for the resulting 1:1 complexes with trivalent lanthanide ions. The complexes have stabilities comparable to 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane (dtma) complexes, with pLn approximately 12-13. Photophysical properties of the ligand and of the EuL3 and TbL3 complexes have been determined for both microcrystalline s les and solutions in water and acetonitrile. They point to the metal ion being present in an environment with axial symmetry derived from the C4 point group. The hydration number determined for TbL3 decreases with increasing pH value and becomes fractional at pH 7.5, which points to an equilibrium between two differently solvated species and probably to the participation of the deprotonated carboxylic acid chain in the complexation. The quantum yields in water (1.9% for EuIII, 3.4% for TbIII) are smaller than those for complexes with the symmetrically substituted parent macrocycle, but efficient luminescence resonant energy transfer (LRET) was observed when Cy5 dye was added to the solutions. Finally, the influence of the TbL3 complex on cell viability is tested on both malignant (5D10 mouse hybridoma, Jurkat human T leukaemia, MCF-7 human breast carcinoma) and non-malignant (Hacat human keratinocyte) cell lines. Cell viability after 24 h incubation at 37 degrees C with 500 microM TbL3 was >90% for all cell lines, except Jurkat (>70%). All of these properties make LnL3 complexes interesting potential probes for bioanalyses.
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B701482A
Abstract: Water-soluble triple-stranded [Ln(2)(L)(3)] helicates have been successfully tested as imaging probes in human cervical adenocarcinoma cells (HeLa), the complex being not toxic and clearly staining their cytoplasm in a concentration-dependent manner.
Publisher: Wiley
Date: 05-2004
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B807959E
Abstract: A versatile and robust method for the determination of DNA and PCR products ( 0.1 ng microL(-1) (dsDNA, ssDNA or circular DNA), the quenched luminescence is reinstated, AO and EB intercalating into DNA, which removes the interaction with the Eu(III) complexes. The best results are obtained with [Eu(2)(L(C2))(3)]/AO with detections limits in the range 0.18-0.66 ng microL(-1) detection limits for the [Eu(L(kel))]/AO system are slightly larger simpler monometallic Eu(III) complexes with dipicolinate derivatives do not follow suit in that they decompose in the presence of DNA. The Eu(III)/AO method is shown to be pH insensitive in the range 3-10 furthermore it is essentially insensitive to 1000-fold excesses of potential interfering substances, e.g. BSA, glucose, chelating agents and anions, alkaline earth and transition metal cations, variations in luminescence intensity being < 5%, (10 analytes) or 5-10% (4 analytes) only Co(II) and Cu(II) interfere substantially.
Location: Switzerland
No related grants have been discovered for Anne-Sophie CHAUVIN.