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Synthesis and Evaluation of Europium Complexes that Switch on Luminescence in Lysosomes of Living Cells
Author(s) -
Starck Matthieu,
Fradgley Jack D.,
Pal Robert,
Zwier Jurriaan M.,
Lamarque Laurent,
Parker David
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202003992
Subject(s) - luminescence , europium , protonation , chemistry , chromophore , endogeny , brightness , absorption (acoustics) , photochemistry , biophysics , analytical chemistry (journal) , inorganic chemistry , materials science , biochemistry , chromatography , optoelectronics , organic chemistry , optics , ion , physics , composite material , biology
A set of four luminescent Eu III complexes bearing an extended aryl‐alkynylpyridine chromophore has been studied, showing very different pH‐dependent behaviour in their absorption and emission spectral response. For two complexes with p K a values of 6.45 and 6.20 in protein‐containing solution, the emission lifetime increases very significantly following protonation. By varying the gate time during signal acquisition, the ‘switch‐on’ intensity ratio could be optimised, and enhancement factors of between 250 to 1330 were measured between pH 8 and 4. The best‐behaved probe showed no significant emission dependence on the concentration of endogenous cations, reductants, and serum albumin. It was examined in live‐cell imaging studies to monitor time‐dependent lysosomal acidification, for which the increase in observed image brightness due to acidification was a factor of 50 in NIH‐3T3 cells.