Jean-Claude Bunzli - A polyoxyethylene-substituted bimetallic europium helicate for luminescent staining of living cells

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      Publication Details (including relevant citation   information):

      Chauvin,A.S., Comby,S., Song,B., Vandevyver,C.D.B., Thomas,F.,   Bunzli,J.C.G. Chemistry-A European Journal  2007 13 (34) 9515-9526

      Abstract: The homoditopic ligand H2LC3 has been   designed to form neutral triple-stranded bimetallic helicates of   overall composition [Ln(2)(L-C3)]. The grafting of the   polyoxyethylene fragments ensures water solubility and also   favors cell penetration while being amenable to further   derivatization. The ligand pK(a) 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 (log beta(23) in the range 22-23). The   ligand triplet state has an adequate energy (0-phonon transition   at approximate to 20800 cm(-1)) for sensitizing the luminescence   of Eu-III (Q=11%). Analysis of the Eu-III emission spectrum   points to an overall pseudo D-3 symmetry for the metal   environment. No significant effect of [Eu-2(L-C3)(3)] is observed   on the viability of several cancerous cell lines (MCF-7, HeLa,   Jurkat, and 5D10). The cell imaging properties of the Eu-III.   helicate are demonstrated for the HeLa cell line by luminescence   microscopy. Bright Eu-III emission is seen for helicate   concentration > 50 mu m and after 20-30 min loading time. The   helicate stains the cytoplasm and the permeation mechanism is   likely to be endocytosis

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