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Comparative Analysis of a Series of pH‐Responsive Sulphonated Europium Complexes for Bioassays Monitoring Acidification

Fradgley, Jack D. and Starck, Matthieu and Lamarque, Laurent and Parker, David (2022) 'Comparative Analysis of a Series of pH‐Responsive Sulphonated Europium Complexes for Bioassays Monitoring Acidification.', European journal of inorganic chemistry. .


The synthesis and photophysical evaluation of a series of hydrophilic sulphonated and pH responsive luminescent europium(III) probes are reported. The Eu emission intensities and lifetimes increase very significantly on lowering pH, leading to a ‘switching on’ of Eu luminescence in more acidic media. By varying the nature of the substituents at an integral aniline nitrogen atom located in the sensitising chromophore, the pKa value of the complex can be tuned to between 4.3 and 6.3 for a set of five Eu(III) complexes. These systems are designed to allow conjugation to targeting vectors permitting, for example, the monitoring of receptor internalisation in cells. This approach can be used to tag proteins selectively and allows the monitoring of uptake into acidic organelles, enabling the creation of time-resolved internalisation assays to follow pH change in real time, both in vitro and in cellulo.

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Publisher statement:© 2022 The Authors. European Journal of Inorganic Chemistry published by Wiley-VCH GmbH This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Date accepted:No date available
Date deposited:05 September 2022
Date of first online publication:12 August 2022
Date first made open access:05 September 2022

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