Hg 2+ has a significant hazardous impact on the environment and ecosystem. There is a great demand for new methods with high selectivity and sensitivity to determine mercury in life systems and environments. In this paper, a novel turn-on Hg 2+ fluorescent probe has been reported with a naphthalimide group. The Hg 2+ fluorescent probe was designed by the inspiration of the well-known specific Hg 2+ -triggered thioacetal deprotection reaction. A 1,2-dithioalkyl group was chosen as the specific recognition site of Hg 2+ . The probe showed weak fluorescence without Hg 2+ , and the color of the solution was light yellow. In the presence of Hg 2+ , the probe reacted specifically with the mercury ion to produce an aldehyde and emitted strong fluorescence, and the color of the solution also turned light green, thus realizing the monitoring of the mercury ion. The Hg 2+ fluorescent probe showed outstanding sensitivity and selectivity toward Hg 2+ . Furthermore, the Hg 2+ fluorescent probe could work in a wide pH range. The linear relationship between the fluorescence intensity at 510 nm and the concentration of Hg 2+ was obtained in a range of Hg 2+ concentration from 2.5 × 10 –7 to 1.0 × 10 –5 M. The detection limit was found to be 4.0 × 10 –8 M for Hg 2+ . Furthermore, with little cell toxicity, the probe was successfully applied to the confocal image of Hg 2+ in PC-12 cells.

A ratiometric fluorescent probe for detecting cysteine was designed and synthesized based on the fluorescence resonance energy transfer (FRET) process.

As a key reactive oxygen species (ROS), hypochlorous acid (HClO) plays an important role in many physiological and pathological processes. The mitochondria-targeting probes for the highly sensitive detection of HClO are desirable. In present work, we designed and synthesized an original mitochondria-localizing and turn-on fluorescent probe for detecting HClO. 4-Aminonaphthalimide was employed as the fluorescent section, the (2-aminoethyl)-thiourea unit was utilized as a typical sensing unit, and the quaternized pyridinium moiety was used as a mitochondria-targeted localization group. When HClO was absent, the probe showed weak fluorescence. In the existence of HClO, the probe revealed a blue fluorescence. Moreover, the turn-on fluorescent probe was able to function in a broad pH scope. There was an excellent linearity between the fluorescence emission intensity at 488 nm and the concentrations of HClO in the range of 5.0 × 10–7 to 2.5 × 10–6 mol·L–1. Additionally, the probe had almost no cell toxicity and possessed an excellent mitochondria-localizing capability. Furthermore, the probe was able to image HClO in mitochondria of living PC-12 cells. The above remarkable properties illustrated that the probe was able to determine HClO in mitochondria of living cells.

As a key reactive oxygen species (ROS), hypochlorous acid (HClO) plays a vital role in living system. The ratiometric and endoplasmic reticulum-targeting probes for the high sensitive detection of hypochlorous...

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