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Hypochloric acid (HClO) is mainly distributed in acidic lysosomes of phagocytes and closely associated with numerous physiological and pathological processes, especially inflammatory response. Fluorescent probe has become an important tool for imaging HClO in lysosomes, but suffered from interference from autofluorescence in vivo , phototoxicity to biosamples and photobleaching phenomenon due to their short-wavelength excitation and emission. Unfortunately, up to now, no near-infrared (NIR) lysosome-targetable fluorescent probe has been reported for imaging HClO. In this paper, a near-infrared fluorescent probe Lyso - NIR - HClO for imaging lysosomal HClO was reported for the first time. Lyso - NIR - HClO based on Si-rhodamine is consisted of a morpholine unit as a lysosome-targetable group and a HClO-mediated cyclization reaction site as a response group, which was applied for highly selective and sensitive detection and imaging for endogenous and exogenous HClO in lysosomes, with a linear range from 5.0 × 10 −8 to 1.0 × 10 −5 M and a detection limit of 2.0 × 10 −8 M in vitro . Attributed to NIR emission and excellent photostability of Si-rhodamine, Lyso - NIR - HClO exhibits excellent performances in vivo , such as low interference from intracellular autofluorescence, stable and persistent fluorescence signal and good tissue penetration, which are in favor of accurate, time-lapse and long-term imaging for HClO. Finally, we applied the probe Lyso - NIR - HClO to visualize endogenous HClO during lysosome-involved inflammatory response including bacteria-infected cells and inflamed mouse model with satisfactory results. The above results proved that Lyso - NIR - HClO would be a potentially useful tool for the study of biological functions and pathological roles of HClO in lysosomes, especially role of lysosome in the inflammatory response.

A fluorescent probe 1 for Hg(2+) based on a rhodamine-coumarin conjugate was designed and synthesized. Probe 1 exhibits high sensitivity and selectivity for sensing Hg(2+), and about a 24-fold increase in fluorescence emission intensity is observed upon binding excess Hg(2+) in 50% water/ethanol buffered at pH 7.24. The fluorescence response to Hg(2+) is attributed to the 1:1 complex formation between probe 1 and Hg(2+), which has been utilized as the basis for the selective detection of Hg(2+). Besides, probe 1 was also found to show a reversible dual chromo- and fluorogenic response toward Hg(2+) likely due to the chelation-induced ring opening of rhodamine spirolactam. The analytical performance characteristics of the proposed Hg(2+)-sensitive probe were investigated. The linear response range covers a concentration range of Hg(2+) from 8.0x10(-8) to 1.0x10(-5)molL(-1) and the detection limit is 4.0x10(-8)molL(-1). The determination of Hg(2+) in both tap and river water samples displays satisfactory results.