A BODIPY-based fluorescent probe, HCSe, has been successfully developed for the rapid detection of hypochlorous acid based on the specific HOCl-promoted oxidation of diphenyl selenide in response to the amount of HOCl. Confocal fluorescence microscopy imaging using RAW264.7 cells showed that the new probe HCSe could be used as an effective fluorescent probe for detecting HOCl in living cells.

A new coumarin-derived fluorescent probe (1) exhibited significant fluorescence quenching in the presence of Cu2+ ions.

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In this study, a boron-dipyrromethene (BODIPY)-based fluorescent chemosensor CBS was developed for metal ion sensing. It was found that CBS containing an NSe2 moiety exhibited high selectivity for Cu(2+) detection while CBS in the presence of Cu(2+) displayed significant fluorescence enhancement. However, the metal ions Ag(+), Ca(2+), Co(2+), Cr(3+), Fe(2+), Fe(3+), Hg(2+), K(+), Mg(2+), Mn(2+), Ni(2+), Pb(2+), and Zn(2+) produced only minor changes in the fluorescence values of the system. The binding constant (Ka) of Cu(2+) binding to CBS was found to be 7.28 × 10(3) M(-1). The binding ratio of CBS-Cu(2+) complexes was determined from the Job plot to be 1 : 1. The maximum fluorescence enhancement caused by Cu(2+) binding to CBS was observed over the pH range 5.0-9.0. Additionally, the methyl thiazolyl tetrazolium (MTT) assay demonstrated the CBS to have low cytotoxicity. Confocal fluorescence microscopy imaging using RAW264.7 cells showed that CBS could be used as an effective fluorescent probe for detecting Cu(2+) in living cells.

A new 7-nitrobenz-2-oxa-1,3-diazole (NBD) derived fluorescent probe (1) exhibiting high selectivity for Cu(2+) detection, produced significant fluorescence quenching in the presence of Cu(2+) ion, while the metal ions Ca(2+), Cd(2+), Co(2+), Fe(2+), Hg(2+), Mg(2+), Mn(2+), Ni(2+) and Zn(2+) produced only minor changes in fluorescence. The apparent association constant (K (a)) for Cu(2+) binding in chemosensor 1 was found to be 1.22 × 10(3) M(-1). The maximum fluorescence quenching activity caused by Cu(2+) binding to 1 was observed over the pH range 6-10.

We chemically tuned the oxidation status of graphene oxide (GO) and constructed a GO-based nanoplatform combined with a pH-sensitive fluorescence tracer that is designed for both pH sensing and pH-responsive drug delivery. A series of GOs oxidized to distinct degrees were examined to optimize the adsorption of the model drug, poly dT30. We determined that highly oxidized GO was a superior drug-carrier candidate in vitro when compared to GOs oxidized to lesser degrees. In the cell experiment, the synthesized pH-sensitive rhodamine dye was first applied to monitor cellular pH; under acidic conditions, protonated rhodamine fluoresces at 588 nm (λex=561 nm). When the dT30-GO nanocarrier was introduced into cells, a rhodamine-triggered competition reaction occurred, and this led to the release of the oligonucleotides and the quenching of rhodamine fluorescence by GO. Our results indicate high drug loading (FAM-dT30/GO=25/50 μg/mL) and rapid cellular uptake (<0.5 h) of the nanocarrier which can potentially be used for targeted RNAi delivery to the acidic milieu of tumors.