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New Class of Tetradentate β-Diketonate-Europium Complexes That Can Be Covalently Bound to Proteins for Time-Gated Fluorometric Application

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journal contribution
posted on 2016-02-20, 18:57 authored by Lin Zhang, Yanjiao Wang, Zhiqiang Ye, Dayong Jin, Jingli Yuan
Luminescent lanthanide complexes that can be covalently bound to proteins have shown great utility as biolabels for highly sensitive time-gated luminescence bioassays in clinical diagnostics and biotechnology discoveries. In this work, three new tetradentate β-diketonate–europium complexes that can be covalently bound to proteins to display strong and long-lived Eu3+ luminescence, 1,2-bis­[4′-(1″,1″,1″,2″,2″,3″,3″-heptafluoro-4″,6″-hexanedion-6″-yl)-benzyl]-4-chlorosulfobenzene-Eu3+ (BHHBCB-Eu3+), 1,2-bis­[4′-(1″,1″,1″,2″,2″-pentafluoro-3″,5″-pentanedion-5″-yl)-benzyl]-4-chlorosulfobenzene-Eu3+ (BPPBCB-Eu3+), and 1,2-bis­[4′-(1″,1″,1″-trifluoro-2″,4″-butanedion-4″-yl)-benzyl]-4-chlorosulfobenzene-Eu3+ (BTBBCB-Eu3+), have been designed and synthesized as biolabels for time-gated luminescence bioassay applications. The luminescence spectroscopy characterizations of the aqueous solutions of three complex-bound bovine serum albumin reveal that BHHBCB-Eu3+ has the strongest luminescence with the largest quantum yield (40%) and longest luminescence lifetime (0.52 ms) among the complexes, which is superior to the other currently available europium biolabels. The BHHBCB-Eu3+-labeled streptavidin was prepared and used for both the time-gated luminescence immunoassay of human prostate specific antigen and the time-gated luminescence microscopy imaging of a pathogenic microorganism Cryptosporidium muris. The results demonstrated the practical utility of the new Eu3+ complex-based biolabel for time-gated luminescence bioassay applications.