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A single-chromophore-based photoactive agent (MB-DOPA) capable of rapid sensing of nanomolar hypochlorous acid (HOCl) and in-situ generating photocytotoxicity to cancer cells was developed using dopamine moiety as the recognition unit and methylene blue (MB) moiety as the fluorescence signaling unit. Specifically, HOCl triggered conversion of the nonfluorescent MB-DOPA to MB enabling far-red fluorescence emission (λmax ∼ 683 nm) and additional ability to photogenerate 1O2 species. Owing to the catechol nature of dopamine characterized with strong electron-donating property, MB-DOPA underwent HOCl-mediated conversion with response time of ∼20 s and a strong fluorescence OFF-to-ON contrast by a factor of more than 3000. The preliminary bioimaging results confirmed the intracellular HOCl sensing ability of MB-DOPA and the in-situ photodynamic therapy (PDT) effectiveness for inducing massive apoptosis of cancer cells. The figure of merits of MB-DOPA, including ability for sensing of nanomolar HOCl with high specificity, rapid response, practicality for intracellular fluorescence imaging, and the in-situ generation of 1O2 for killing tumor cells, is expected to enable diagnosis of early-stage oncogenesis based on the highly specific detection of abnormal HOCl levels in the transformed cells and the simultaneous treatment in biomedical applications.

A new type of fluorescent probe capable of detecting Ag+ and Hg2+ in two independent channels was developed in the present work. Specifically, in CH3CN–MOPS mixed solvents with CH3CN/MOPS ratio (v/v) of 15/85, this type of probe fluoresced weakly, and the addition of Ag+ remarkably induced fluorescence enhancement of the probe. In CH3CN–MOPS mixed solvents with the percentage of CH3CN increased up to 65%, the probe was highly fluorescent and addition of Hg2+ dramatically induced the fluorescence quenching. Thus, using such single-fluorophore-based probe and tuning the polarity of the mixed solvent, Ag+, and Hg2+ can be detected in independent channels with high selectivity and sensitivity. As a result, the mutual interference usually encountered in most cases of Ag+ and Hg2+ sensing owing to the similar fluorescence response that these two ions induced, can be effectively circumvented by using the probes developed herein.

A new type of fluorescent probe capable of detecting Ag(+) and Hg(2+) in two independent channels was developed in the present work. Specifically, in CH3CN-MOPS mixed solvents with CH3CN/MOPS ratio (v/v) of 15/85, this type of probe fluoresced weakly, and the addition of Ag(+) remarkably induced fluorescence enhancement of the probe. In CH3CN-MOPS mixed solvents with the percentage of CH3CN increased up to 65%, the probe was highly fluorescent and addition of Hg(2+) dramatically induced the fluorescence quenching. Thus, using such single-fluorophore-based probe and tuning the polarity of the mixed solvent, Ag(+), and Hg(2+) can be detected in independent channels with high selectivity and sensitivity. As a result, the mutual interference usually encountered in most cases of Ag(+) and Hg(2+) sensing owing to the similar fluorescence response that these two ions induced, can be effectively circumvented by using the probes developed herein.