A rhodamine/BODIPY-based fluorescent probe for the differential detection of Hg(ii) and Au(iii)

Abstract

We described the design and synthesis of a molecular sensor based on a rhodamine/BODIPY platform that displayed differential fluorescence responses towards Hg 2+ and Au 3+ and demonstrated its utility in intracellular ion imaging.In recent years, the construction of fluorescent molecular sensors for the detection of metal ion species has received a great deal of attention. 1 To date a large number of molecular sensors have been designed and developed, the majority of which are single-ion responsive and present no great challenge to researchers. Compared to single-ion responsive molecular sensors, however, the construction of multi-ion responsive molecular sensors with multiple emission modes are extremely challenging. 2 Molecular sensors displaying differential responses towards multiple ions are indispensable for designing molecular logic gates and molecular keypad lock devices. 3,4The challenge of multiple analyte recognition presents several detection strategies. Incorporating multiple binding motifs onto a single sensing molecule, or alternatively, combining different transducing units (chromophores/fluorophores), allows for rapid access to molecular sensors with multiple emission modes. 2 We envisaged that incorporating both a chemosensor and a chemodosimeter onto a single molecule could provide a suitable sensing platform for the differential detection of metal species. On the basis of this hypothesis, we constructed a molecular sensor possessing two different fluorophore units chemically integrated with each other. Both fluorophore units were elegantly designed to be non-emissive (i.e., ''off'') in their initial states and are expected to turn on respectively in response to the metal species of interest. To the best of our knowledge, molecular sensors based on this novel approach have not been covered in the literature.Ionic species of mercury (Hg 2+ ) and gold (Au 3+) share several similarities in terms of coordination properties. As both metal species show high affinities to thiols, they have the potential to interact with sulfur bearing biomolecules such as enzymes, proteins, and DNA. As a result, these metal species can disturb a series of cellular processes that lead to toxicity in humans. . This fluorescent probe, reported by Dong et al., operates through a single emission mode and the differentiation is highly dependent on the sensing conditions. Obviously, there is a high demand for the development of molecular sensors that can differentiate multiple analytes of a similar chemical nature (e.g. Hg 2+ and Au 3+ ). In addition, smallmolecule fluorescent sensors allowing the intracellular monitoring of multiple ions via differential responses are of high necessity for real-time cell imaging studies. Herein, we present the design, synthesis, spectral properties, and cell imaging studies of RhS-BOD, a new ''turn-on'' multifluorescent probe that allows the Hg 2+ and Au 3+ species to be differentiated on the basis of distinct fluorescence responses. RhS-BOD constitutes a boron-dipyrromethene (BODIPY...

Synthesis and properties of three novel rhodamine-based fluorescent sensors for Hg2+

“…A large number of 1,8-naphthalimide [5][6][7], rhodamine [8][9][10][11][12], BODIPY [13][14][15], coumarin [16,17], and dansyl-based [18,19] Hg 2+ fluorescent sensors have been reported. However, some of them could only respond to Hg 2+ in organic media [9,11,13], others suffered from poor sensing properties including selectivity, sensitivity, interference immunity and practicability [8,12,20].…”

Design of a novel coumarin-based multifunctional fluorescent probe for Zn2+/Cu2+/S2− in aqueous solution

“…However, the simultaneous detection and identification of multiple ions by multifunctional fluorescent probe is still few in number. Compared to single-ion responsive molecular sensors, the multifunctional sensors have been actively developed because of the advantages such as analytical time reduction [27][28][29]. Coumarin is a kind of compound with great fluorescent intensity, high quantum yield, and is very suitable to act as fluorescent chromophores [30][31][32][33].…”

A guanidinium modified rhodamine-based fluorescent probe for in vitro/vivo imaging of gold ions

“…Alternative sensing events such as C]N bond hydrolysis [25][26][27] and reversible ion-dipole interactions 21 have also been employed for signal modulation. However, several challenges continue to impede the optimum performance of such sensing systems, for example, chronical interference of other metal ions.…”

“…Given their impressive photophysical properties, uorescent molecules such as rhodamine, [17][18][19][20][21][22][23] boron-dipyrromethene (BODIPY), [24][25][26][27] uorescein 28-30 and naphthalimide 31,32 are most commonly employed as signal transducers.…”