A turn-on anthraquinone-derived colorimetric and fluorometric dual-mode probe for highly selective Hg 2+ determination and bioimaging in living organisms.

Mercury ion (Hg ²⁺ ) is considered a harmful neurotoxin, and real-time monitoring of Hg ²⁺ concentrations in environmental and biological samples is critical. Fluorescent probes are a rapidly emerging visualization tool owing to their simple design and good selectivity. Herein, a novel fluorescence (FL) probe 2-(4-((6-((quinolin-8-yloxy)methyl)pyridin-2-yl)methyl)piperazin-1-yl)anthracene-9,10-dione (QPPA) is designed using piperazine as a linker between the anthraquinone group, which serves as a fluorophore, and N ₄ O as the Hg ²⁺ ligand. The probe exhibits FL "turn-on" sensing of Hg ²⁺ because the complex inhibits the photo-induced electron transfer (PET) process. Moreover, QPPA can overcome the invasion by other possible cations, resulting in a clear color change from orange to colorless with the addition Hg ²⁺ . The chelation of QPPA with Hg ²⁺ in a 1:1 ratio. Subsequently, the theoretically determined binding sites of the ligand to Hg ²⁺ are validated through ¹ H NMR titration. The in situQPPA-Hg ²⁺ complex can be subjected to Hg ²⁺ extraction following the introduction of S ^2- owing to its robust binding capacity. The exceptional limit of detection values for Hg ²⁺ and S ^2- are obtained as 63.0 and 79.1 nM (S/N = 3), respectively. Moreover, QPPA can display bright red FL in the presence of Hg ²⁺ in different biological specimens such as HeLa cells, zebrafish, onion root tip tissues, and water flea Daphnia carinata, further providing an effective strategy for environmental monitoring and bioimaging of Hg ²⁺ in living organisms.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Declaration of competing interest The authors declare that there are no competing financial interests or personal relationships that influence our work.
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