A Polyoxyethylene-Substituted Bimetallic Europium Helicate for Luminescent Staining of Living Cells
✍ Scribed by Anne-Sophie Chauvin; Steve Comby; Bo Song; Caroline D. B. Vandevyver; Frédéric Thomas; Jean-Claude G. Bünzli
- Book ID
- 102794649
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 515 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0947-6539
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
The homoditopic ligand H~2~L^C3^ has been designed to form neutral triple‐stranded bimetallic helicates of overall composition [Ln~2~(L^C3^)~3~]. The grafting of the polyoxyethylene fragments ensures water solubility and also favors cell penetration while being amenable to further derivatization. The ligand p__K__~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 (logβ~23~ in the range 22–23). The ligand triplet state has an adequate energy (0–phonon transition at ≈20 800 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 μM and after 20–30 min loading time. The helicate stains the cytoplasm and the permeation mechanism is likely to be endocytosis.