UV and fluorescent spectra study the reaction between 1, 8-Naphthalimide derivative and hypochlorite their applications

ICT-modulated NIR water-soluble fluorescent probe with large Stokes shift for selective detection of cysteine in living cells and zebrafish

The fluorescent probes with good water-solubility, long-wavelength emission and large Stokes shift are greatly desirable for in vivo detection. Herein, we designed a novel 1,8-naphthalimide-based near-infrared (NIR) optical and fluorescent probe (NTC) for sensing cysteine (Cys). Using acrylate as the recognition site, the probe demonstrated high selectivity and sensitivity for Cys with a low detection limit (0.093 μM) in aqueous buffer solution due to the excellent water-solubility. Upon the reaction with Cys, the recovery of intramolecular charge transfer (ICT) in the probe led to about 40-fold fluorescence enhancement. Furthermore, the reaction result was investigated by ¹H NMR, and HRMS analyses, and the sensing mechanism was validated by quantum calculations. Finally, NTC was applied to image exogenous and endogenous Cys in HeLa cells and zebrafish selectively, implying that the probe possessed great potential application in biological fluorescence sensing.

Malononitrile as the 'double-edged sword' of passivation-activation regulating two ICT to highly sensitive and accurate ratiometric fluorescent detection for hypochlorous acid in biological system

Hypochlorous acid (HOCl) as one of the most important reactive oxygen species in the organism, its role is more and more recognized. In fact, in recent years, various HOCl fluorescent probes have been developed unprecedentively based on various mechanisms. However, because most of the mechanisms are based on the oxidation characteristics of HOCl, the excellent detection performance of probes depends on the activation ability of some functional groups to reaction sites. The C[bond, double bond]C bond in the probe is often oxidized by HOCl to realize HOCl detection. However, due to the break of conjugated structure, the probe often present as a quenchable or turning on fluorescence emission. In this work, malononitrile was introduced as the "double-edged sword" of passivation-activation when in HOCl fluorescent probe was designed. Passivation-activation regulated two ICT (Intermolecular Charge Transfer, ICT) processes to ratiometric fluorescent detection for HOCl. Highly sensitive and accurate detection realized efficient application in biological imaging.

Sensitive and selective fluorescent probe for hypochlorite in 100% aqueous solution and its application for lysosome-targetable cell imaging

A morpholine-functionalized pyrrole-cyanine probe was synthesized via a simple condensation reaction in high yield. This probe exhibits high selectivity toward ClO^- on fluorescence and UV-vis spectra in neat aqueous solution. The strong green emission of the probe solution was quenched and the yellow color faded immediately upon the addition of ClO^-. The detection limit of the probe for ClO^- was 0.165 μM. The mechanism of hypochlorite-induced CC breakage was supposed on the basis of EIS-MS, NMR, and density functional theory (DFT) calculation. Finally, the probe was utilized to image ClO^- in lysosomes of living cells.

Sunlight and UV driven synthesis of Ag nanoparticles for fluorometric and colorimetric dual-mode sensing of ClO

A photo-responsive compound BINOL-LA (1) having a rigid backbone ending up with two 5-membered cyclic disulfide moieties was designed. BINOL-LA capped Ag nanoparticles (1@Ag NPs) with a network structure were synthesized in a green way by sunlight or UV lamp irradiation. 1@Ag NPs exhibit a selective recognition towards ClO^- in aqueous solution with a switch-on fluorescence response and a visual color change, with detection limits of 0.17 μM and 1.54 μM, respectively. The sensing mechanism is based on the ClO^--mediated oxidation of AgS bond, resulting in a disaggregation of 1@Ag NPs assembly. With the strategy demonstrated here, ClO^- in tap water and lake water can be detected quantitatively in 5 s.

An o-hydroxyl aldehyde structure based naphthalimide derivative: Reversible photochromic properties and its application in ClO- detection in living cells

A bifunctional organic compound 2-butyl-6-hydroxy-1,3-dioxo-2,3-dihydro-1H-benzo[de] isoquinoline-5-carbaldehyde (BHC) with photochromic properties in solid state and probe detection for ClO^- in complete water solution was synthesized and fully characterized. A 'white-yellow-white' reversible photochromic behavior could be observed when alternating UV/vis light irradiation on the solid BHC powder. Good fatigue resistance and adjustable bleaching rate were shown when heating conditions changes. In addition, BHC displayed a high selectivity and low detection limit (1.16 × 10^-8 M) for ClO^-. The photoluminescent fluorescence "on-off" recognition result can be easily identified and BHC has been tested for safely imaging living cells and detecting hypochlorite anion in vitro and vivo. A better water solubility of BHC effectively reduces damage caused by organic solvent in cell imaging progress.

A novel coumarin-based fluorescent probe with fine selectivity and sensitivity for hypochlorite and its application in cell imaging

It is necessary to develop simple and highly sensitive methods for the detection of hypochlorous acid (HOCl)/hypochlorite (ClO^-) to ravel its relationship with disease. In this paper, a novel bio-compatible fluorescent (Z)-8-(hydrazonomethyl)-7-hydroxy-4-methyl-2H-chromen-2-one (probe 1b) based on coumarin was synthesized and used for detecting ClO^- in PBS buffer (pH = 7.2, 10 mM, 60% C₂H₅OH). Probe 1b showed a remarkable fluorescence change from yellow to blue with the limit of detection as low as 2.4 × 10^-9 M^-1 when ClO^- was added. The coexisted anions, metal ions and reactive oxygen species (•OH, ¹O₂, H₂O₂, KO₂) showed any competitiveness towards ClO^-. In response to ClO^-, the fluorescence emission intensity of probe 1b was obviously enhanced within 20 s. The mechanism was confirmed by the ESI - MS and density functional theory calculations (DFT) to reveal that the coumarin lactone bonds C - O was cleavaged by oxidation of ClO^-. What's more, probe 1b could be used in practical water samples and showed well recovery. Additionally, the cell imaging experiment was demonstrated that probe 1b could be effectively exploited to imaging exogenous ClO^- in vitro.

A highly specific and sensitive turn-on fluorescence probe for hypochlorite detection and its bioimaging applications

A new probe, EDPC, was designed and synthesized for highly specific and sensitive detection of ClO⁻ with a fast response time in living cells.

A “turn-on” fluorescent probe for highly selective discrimination of hypochlorite (ClO−) from oxidants including dichromates (Cr2O72−) in aqueous media

A carbazole-based probe was synthesized and found to fluoresce (λ_em,max = 440 nm) in the presence of hypochlorite.

A benzothiazole-based fluorescent probe for hypochlorous acid detection and imaging in living cells

A benzothiazole-based turn-on fluorescent probe with a large Stokes shift (190nm) has been developed for hypochlorous acid detection. The probe displays prompt fluorescence response for HClO with excellent selectivity over other reactive oxygen species as well as a low detection limit of 0.08μM. The sensing mechanism involves the HClO-induced specific oxidation of oxime moiety of the probe to nitrile oxide, which was confirmed by HPLC-MS technique. Furthermore, imaging studies demonstrated that the probe is cell permeable and can be applied to detect HClO in living cells.

Construction of a ratiometric fluorescent probe with an extremely large emission shift for imaging hypochlorite in living cells

Hypochlorite is one of the important reactive oxygen species (ROS) and plays critical roles in many biologically vital processes. Herein, we present a unique ratiometric fluorescent probe (CBP) with an extremely large emission shift for detecting hypochlorite in living cells. Utilizing positively charged α,β-unsaturated carbonyl group as the reaction site, the probe CBP itself exhibited near-infrared (NIR) fluorescence at 662nm, and can display strong blue fluorescence at 456nm when responded to hypochlorite. Notably, the extremely large emission shift of 206nm could enable the precise measurement of the fluorescence peak intensities and ratios. CBP showed high sensitivity, excellent selectivity, desirable performance at physiological pH, and low cytotoxicity. The bioimaging experiments demonstrate the biological application of CBP for the ratiometric imaging of hypochlorite in living cells.

A novel (3,6-di-tert-butylcarbazol-9-yl) triphenylamine–BODIPY–tricyanofuran conjugated dye: synthesis and rapid naked-eye detection of hypochlorite

A colorimetric and ratiometric probe, BCPA–BODIPY–TCF, for hypochlorite (ClO⁻) based on a D–π–A structure was synthesized through the Knoevenagel reaction.