Jean-Claude Bunzli - A novel strategy for the design of 8-hydroxyquinolinate-based lanthanide bioprobes that emit in the near infrared range

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      Publication Details (including relevant citation   information):

      Comby,S., Imbert,D., Vandevyver,C., Bunzli,J.C.G. Chemistry-A   European Journal 2007 13 (3)   936-944

      Abstract: A new polydentate tripodal ligand   T2soxMe was synthesized to take advantage of the chelating effect   of tridentate 8-hydroxyquinolinate subunits. Potentiometric and   spectrophotometric titrations reveal seven pK(a) values of   between 3.7 and 10.2. In water, the use of T2soxMe leads to   thermodynamically stable and soluble Ln(III) complexes at   physiological pH, with conditional stability constants in the   range log beta(11) = 7.8-8.6. The chelates are resistant toward   hydrolysis and show interesting photophysical properties,   particularly in the near infrared (NIR) range. The emission   lifetimes of the Nd(III) and Yb(III) complexes recorded in D(2)O   and H(2)O suggest the absence of water molecules in the first   coordination sphere of the metal ions. Moreover, the low energy   of the triplet state allows efficient energy transfer from the   ligand to the metal ions: in water at pH 7.4, the sensitization   efficacy of the NIR luminescence reaches 75 and approximate to   100% for Nd(III) and Yb(III), respectively, leading to overall   quantum yields of 0.027 and 0.13%; Er(III) luminescence is also   detected. According to the WST-1 test, the Yb(III) podate at   concentrations of up to 250 mu m does not display sizeable   cytotoxicity for Jurkat cells after 24 h of incubation. Finally,   the same podate is shown to couple to human serum albumin,   leading to an increase of 50% in the NIR-luminescence intensity

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