A strategy to enhance the water solubility of luminescent β-diketonate-Europium(III) complexes for time-gated luminescence bioassays

• Published in: Talanta (Oxford) Vol. 274; p. 126000
• Main Authors: Dong, Zhiyuan, Song, Bo, Ma, Hua, Gao, Xiaona, Zhang, Wenzhu, Yuan, Jingli
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.07.2024
• Subjects: Immunoassay; Lanthanide complex; Time-gated luminescence; Water solubility; β-diketone ligands; Time-gated luminescence; Water solubility; β-diketone ligands; Immunoassay; Lanthanide complex
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2024.126000

Luminescent β-diketonate-europium(III) complexes have been found a wide range of applications in time-gated luminescence (TGL) bioassays, but their poor water solubility is a main problem that limits their effective uses. In this work we propose a simple and general strategy to enhance the water solubility of luminescent β-diketonate-europium(III) complexes that permits facile synthesis and purification. By introducing the fluorinated carboxylic acid group into the structures of β-diketone ligands, two highly water-soluble and luminescent Eu3+ complexes, PBBHD-Eu3+ and CPBBHD-Eu3+, were designed and synthesized. An excellent solubility exceeding 20 mg/mL for PBBHD-Eu3+ was found in a pure aqueous buffer, while it also displayed strong and long-lived luminescence (quantum yield φ = 26%, lifetime τ = 0.49 ms). After the carboxyl groups of PBBHD-Eu3+ were activated, the PBBHD-Eu3+-labeled streptavidin-bovine serum albumin (SA-BSA) conjugate was prepared, and successfully used for the immunoassay of human α-fetoprotein (AFP) and the imaging of an environmental pathogen Giardia lamblia under TGL mode, which demonstrated the practicability of PBBHD-Eu3+ for highly sensitive TGL bioassays. The carboxyl groups of PBBHD can also be easily derivatized with other reactive chemical groups, which enables PBBHD-Eu3+ to meet diverse requirements of biolabeling technique, to provide new opportunities for developing functional europium(III) complex biolabels serving for TGL bioassays. Novel water-soluble β-diketonate-Eu3+ complexes for highly sensitive and background-free time-gated luminescent immunoassay and bioiamging. [Display omitted] •The work provides a simple and general strategy to fabricate water-soluble, highly luminescent β-diketonate-Eu3+ complexes for biolabelling.•The prepared Eu3+ complex, PBBHD-Eu3+, could be a useful tool for background-free TGL immunoassay and bioimaging.•The carboxyl groups within the new label offer the potential for additional modifications with various functional groups.