Photoluminescent and electrochemiluminescent dual-signaling probe for bio-thiols based on a ruthenium(II) complex

State Key Laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology, Dalian 116024, PR China.
Analytica chimica acta (Impact Factor: 4.51). 08/2012; 740:80-7. DOI: 10.1016/j.aca.2012.06.028
Source: PubMed


Photoluminescence (PL) and electrochemiluminescence (ECL) detection techniques are highly sensitive and widely used methods for clinical diagnostics and analytical biotechnology. In this work, a unique ruthenium(II) complex, [Ru(bpy)(2)(DNBSO-bpy)](PF(6))(2) (bpy: 2,2'-bipyridine; DNBSO-bpy: 2,4-dinitrobenzenesulfonate of 4-(4-hydroxyphenyl)-2,2'-bipyridine), has been designed and synthesized as a highly sensitive and selective PL and ECL dual-signaling probe for the recognition and detection of bio-thiols in aqueous media. As a thiol-responsive probe, the complex can specifically and rapidly react with bio-thiols in aqueous solutions to yield a bipyridine-Ru(II) complex derivative, [Ru(bpy)(2)(HP-bpy)](2+) (HP-bpy: 4-(4-hydroxyphenyl)-2,2'-bipyridine), accompanied by the remarkable PL and ECL enhancements. The complex was used as a probe for the PL and ECL detections of cysteine (Cys) and glutathione (GSH) in aqueous solutions. The dose-dependent PL and ECL enhancements showed good linear relationships against the Cys/GSH concentrations with the detection limits at nano-molar concentration level. Moreover, the complex-loaded HeLa cells were prepared for PL imaging of the endogenous intracellular thiols. The results demonstrated the practical utility of the complex as a cell-membrane permeable probe for PL imaging detection of bio-thiols in living cells.

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Available from: Run Zhang, Mar 02, 2014
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    • "In previous works, we identified that the MLCT excited state of ruthenium(II) complexes could be corrupted by the intramolecular photoinduced electron transfer (PET) process when an electron donor or acceptor was attached to polypyridyl ligands, and the elimination of PET by the analyte-triggered reaction could restore the MLCT state to switch on the luminescence of the complexes [40e42]. Using this strategy, our group has developed a series of polypyridyl-ruthenium(II) complex-based luminescent chemosensors/probes for reactive oxygen/nitrogen species (ROS/RNS) [22] [28] [40] [41] [43], highly active amino acids [14] [17] [30] and ions [42], and successfully demonstrated their applicability for biosensing and bioimaging [17] [22] [40] [41]. Nevertheless, mechanisms for cellular uptake and distribution of ruthenium(II) complexes in live cells remained ill-defined [16,44e48]. "
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    ABSTRACT: Although considerable efforts have been made for the development of ruthenium(II) complex-based chemosensors and bioimaging reagents, the multisignal chemosensor using ruthenium(II) complexes as the reporter is scarce. In addition, the mechanisms of cellular uptake of ruthenium(II)-based chemosensors and their intracellular distribution are ill-defined. Herein, a new ruthenium(II) complex-based multisignal chemosensor, Ru-Fc, is reported for the highly sensitive and selective detection of lysosomal hypochlorous acid (HOCl). Ru-Fc is weakly luminescent because the MLCT (metal-to-ligand charge transfer) state is corrupted by the efficient PET (photoinduced electron transfer) process from Fc (ferrocene) moiety to Ru(II) center. The cleavage of Fc moiety by a HOCl-induced specific reaction leads to elimination of PET, which re-establishes the MLCT state of the Ru(II) complex, accompanied by remarkable photoluminescence (PL) and electrochemiluminescence (ECL) enhancements. The result of MTT assay showed that the proposed chemosensor, Ru-Fc, was low cytotoxicity. The applicability of Ru-Fc for the quantitative detection of HOCl in live cells was demonstrated by the confocal microscopy imaging and flow cytometry analysis. Dye colocalization studies confirmed very precise distribution of the Ru(II) complex in lysosomes, and inhibition studies revealed that the caveolae-mediated endocytosis played an important role during the cellular internalization of Ru-Fc. By using Ru-Fc as a chemosensor, the imaging of the endogenous HOCl generated in live macrophage cells during the stimulation was achieved. Furthermore, the practical applicability of Ru-Fc was demonstrated by the visualizing of HOCl in laboratory model animals, Daphnia magna and zebrafish. Copyright © 2015 Elsevier Ltd. All rights reserved.
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