Naphthalimide−Porphyrin Hybrid Based Ratiometric Bioimaging Probe for Hg²⁺: Well-Resolved Emission Spectra and Unique Specificity

Abstract

In this paper, we unveil a novel naphthalimide-porphyrin hybrid based fluorescence probe (1) for ratiometric detection of Hg(2+) in aqueous solution and living cells. The ratiometric signal change of the probe is based on a carefully predesigned molecule containing two independent Hg(2+)-sensitive fluorophores with their maximal excitation wavelengths located at the same range, which shows reversibly specific ratiometric fluorescence responses induced by Hg(2+). In the new developed sensing system, the emissions of the two fluorophores are well-resolved with a 125 nm difference between two emission maxima, which can avoid the emission spectra overlap problem generally met by spectra-shift type probes and is especially favorable for ratiometric imaging intracellular Hg(2+). It also benefits from a large range of emission ratios and thereby a high sensitivity for Hg(2+) detection. Under optimized experimental conditions, the probe exhibits a stable response for Hg(2+) over a concentration range from 1.0 x 10(-7) to 5.0 x 10(-5) M, with a detection limit of 2.0 x 10(-8) M. The response of the probe toward Hg(2+) is reversible and fast (response time less than 2 min). Most importantly, the ratiometric fluorescence changes of the probe are remarkably specific for Hg(2+) in the presence of other abundant cellular metal ions (i.e., Na(+), K(+), Mg(2+), and Ca(2+)), essential transition metal ions in cells (such as Zn(2+), Fe(3+), Fe(2+), Cu(2+), Mn(2+), Co(2+), and Ni(2+)), and environmentally relevant heavy metal ions (Ag(+), Pb(2+), Cr(3+), and Cd(2+)), which meets the selective requirements for biomedical and environmental monitoring application. The recovery test of Hg(2+) in real water samples demonstrates the feasibility of the designed sensing system for Hg(2+) assay in practical samples. It has also been used for ratiometric imaging of Hg(2+) in living cells with satisfying resolution, which indicates that our novel designed probe has effectively avoided the general emission spectra overlap problem of other ratiometric probes.

Optical sensor: a promising strategy for environmental and biomedical monitoring of ionic species

“…300) based on the naphthalimide chromophore and thioether-rich crown receptor as a dual signaling probe for Hg 2+ and Ag + in aqueous solution. Li et al 462 reported a novel naphthalimide-porphyrin hybrid fluorescence probe 341 (Fig. Upon introduction of mercury, a drastic change in the fluorescence take place by the 5-fold enhancement in the intensity of the emission signal with slight blue shift from 547 to 532 nm but there was no change in the absorption signal at 440 nm.…”

Study of Multiporphyrin Compounds as Colorimetric Sitting‐Atop Metal Complexes: Synthesis and Photophysical Studies

“…[9] The detection of heavy-metal ions, such as Hg 2 + ,C d 2 + ,a nd Pb 2 + are of interestf or environmental and health-related issues. [10,11] These metals are pollutantsa nd extremely toxic, therebya lteringt he biological activity of important constituents of living cells. [12][13][14][15] Other important metals, such as zinc(II), Mono-, di-, tri-, and hexaporphyrin derivatives were synthesized and their sensorial ability toward Na + ,L i + ,C a 2 + ,C u 2 + , Ni 2 + ,C o 2 + ,F e 3 + ,Z n 2 + ,C d 2 + ,H g 2 + ,A g + ,C r 3 + ,P b 2 + ,a nd Al 3 + was explored by absorption and emission spectroscopy and 1 HNMR spectroscopy.F or all of the studied porphyrin derivatives the most significant spectral changes were observed upon addition of Zn 2 + ,C d 2 + ,C u 2 + ,C o 2 + ,P b 2 + ,H g 2 + ,a nd Fe 3 + ,w hichr esulted in ac olor change from red to green.…”

Development and Applications of Fluorogenic Probes for Mercury(II) Based on Vinyl Ether Oxymercuration

“…Therefore, numerous fluorescent chemosensors and chemodosimeters have been reported in the literature 19–22. These methods may facilitate mercury analyses, even if they are only semiquantitative.…”

“…Because mercury is a soft Lewis acid, a vast majority of the chemosensors and chemodosimeters for mercury contain sulfur atom(s) that can tightly coordinate the metal as part of off-on fluorescence switches 19,21. Some of the chemosensors and chemodosimeters were successfully applied to real world “dirty” samples and in biological settings with low concentrations of mercury ions 19,22…”