A pyridyl functionalized rhodamine chemodosimeter for selective fluorescent detection of mercury ions and cell...

Rhodamines gain sustained attention owing to their great potential for probe design applications. Herein, the facile preparation of a new pyridyl functionalized rhodamine dye PR is reported, which has stable fluorescence signal in water with maximum emission peak at 594 nm and Stokes shift of 81 nm. Based on dye PR, a new fluorescent probe PRHg has been developed by modifying the spirolactone of PR with hydrazine hydrate so as to produce spirolactam recognizing group for sensing of Hg²⁺. PRHg exhibits high selectivity and sensitivity towards Hg²⁺ in water/ethanol (v/v = 4/1, pH = 7.0) by a specific Hg²⁺-binding promoted spirolactam ring opening and hydrolyzing process. And, the detection limit for Hg²⁺ is evaluated to be 8.5 nM. Besides, the probe can respond to Hg²⁺ within 40 min and over a wide pH range from 4.0 to 10.0. Moreover, PRHg (40 µM) performs low cytotoxicity to HeLa cells (over 91.0 % cell survival rate), which allows the probe to be employed for tracing intracellular Hg²⁺ by fluorescence imaging.