Design and application of a water-soluble phosphorescent Ru(ii) complex as turn-on sensing material for Hg²⁺

Abstract

A novel phosphorescent chemodosimeter material Ruphen-1 based on a Ru(II) complex has been designed and developed by introducing Hg 2+ -promoted desulfurization and intramolecular cyclic guanylation of thiourea reaction into the luminophor. Ruphen-1 not only possessed a longer excitation wavelength, large Stokes shift and good water solubility, but also exhibited high selectivity and sensitivity only toward Hg 2+ with a rapid turn-on phosphorescence response in an aqueous system over a wide range of pH (4.0-9.0). The detection limit for Hg 2+ could reach 5.4 nM under physiological conditions (pH 7.2). The spectral response mechanism and structure changes of the chemodosimeter have been analyzed in detail through theoretical calculations and ESI-MS. Furthermore, by investigating the change in the phosphorescence lifetime of the chemodosimeter and employing the time-resolved emission spectra method, Ruphen-1 could effectively eliminate the interference of background fluorescence and further improve Hg 2+ detection accuracy. Finally, Ruphen-1 showed low cytotoxicity toward living cells through the MTT assay, and exhibited potential applications in the detection and monitoring of the distribution of Hg 2+ in living cells with notable phosphorescence enhancement by confocal luminescence imaging.Scheme 1 (a) The Hg 2+ -induced reaction mechanism and the design principle; (b) structure change of chemodosimeter Ruphen-1.

Theory and Calculation of the Phosphorescence Phenomenon

“…For example, Chermont et al proposed in 2007 a novel in vivo imaging biotechnique by using rare-earth doped nanoparticles with red to near-infrared long-lasting emission (phosphorescence), which greatly improve the signal-to-noise ratio. These new optical labels permit a deep penetration into tissue and constitute the next-generation in modern bioimaging technology. − ,− …”

Ruthenium(II) Complexes with (3-Polyamino)phenanthrolines: Synthesis and Application in Sensing of Cu(II) Ions

“…In this work, we report on the synthesis of chemosensors bearing mixed ligand ([Ru(bpy)2(phen)] 2+ -type complexes as signaling groups. The stable and biocompatible ruthenium(II) tris(diimine) complexes (diimine = bpy, phen, terpyridine) have attracted considerable attention as luminophores and been explored in labeling, sensing, and imaging of various gases (dioxygen [5], nitric oxide [6], and carbon monoxide [7]), biological analytes (DNA, sugars, methylglyoxal, thiols, and amino acids) [8][9][10], and anions [11][12][13][14][15][16][17][18][19]. In contrast to most organic dyes, these complexes can exhibit a high brightness [20] in aqueous media, in part due to the electrostatic repulsive interactions that prevent the aggregation of these charged species in aqueous media.…”

Mito-Specific Ratiometric Terbium(III)-Complex-Based Luminescent Probe for Accurate Detection of Endogenous Peroxynitrite by Time-Resolved Luminescence Assay

“…In order to detect endogenous ONOO − , bacterial endotoxin LPS was incubated with the A-375 cells for 14 h and then incubated with TD-DC for 30 min. The luminescence in the red channel was quenched thoroughly, whereas the luminescence in the green channel increased obviously 39,40 (Figure 5D). To prove the phenomenon is caused by ONOO − , the A-375 cells were further treated with TEMPO, which is a radical scavenger, to eliminate the endogenous ONOO −41,42 (Figure 5E).…”