Sensitive Turn-on Fluorescent Probe Research Articles

Carbazole-alt-fluorene based π-conjugated Cu(II)-metallopolymer with pendent diketopyrrolopyrrole unit as highly selective and sensitive turn-on fluorescent probe for detection of amino acids

Highly emissive and soluble poly(carbazole-alt-fluorene) (P1) based π-conjugated alternative copolymers with thiophene-diketopyrrolopyrrole as pendent unit have been designed and synthesized via Pd(0)-catalyzed Suzuki coupling polymerization from the corresponding monomers 3,6-dibromo-9H-carbazol-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole and 2,7-bis-oxaborolan-9,9-dioctylfluorene. The well-defined copolymer P1 has been characterized by multinuclear NMR spectra as well as by tetradetector GPC showing molecular weight (Mn) of 15.6 kg/mol with the polydispersity indices of 1.38. The red emissive polymer has been explored for the detection of amino acids based on a secondary ‘‘turn-on’’ sensing approach. The thiophene-diketopyrrolopyrrole anchored carbazole-alt-fluorene copolymer shows high selectivity towards Cu2+ ions by changing the emission wavelength from red to blue due to the formation of the Cu(II)-metallopolymer (P1–Cu2+). The resulting metallopolymer P1–Cu2+ exhibits high sensitivity and selectivity towards amino acids over the other biologically relevant analytes. More importantly, the P1–Cu2+ metallopolymer exhibited higher sensitivity towards glycine, with the detection limit of 90 ppb (∼1.21 × 10−6 mol/L) along with relatively higher association constant of 2.55 × 108 M−1. To comprehend the sensing mechanism through photo-induced electron transfer (PET), the detailed photophysical studies have been carried out with P1 and its representative monomeric model compound M1. Furthermore, fluorescence anisotropy study has also been carried out to inspect the molecular interactions responsible for the sensing properties of P1–Cu2+ metallopolymer towards glycine.

Fluorescence turn-on detection of tannic acid using a 6,7-dihydroxycoumarin-Fe3+ complex

Tannic acid (TA) is a natural polyphenolic compound widely distributed in plants and is extensively associated with medicine, food and leather. In this study, we developed a highly sensitive turn-on fluorescent probe for TA using an ensemble of 6,7-dihydroxycoumarin (DHC) and Fe3+ (DHC-Fe). DHC-Fe exhibited high selectivity over gallic acid and vitamin C, which avoided sample pretreatment so that simplified the detection process. Furthermore, DHC-Fe was successfully applied to detect TA in vegetable-tanned leather and in beverage samples. A portable paper-based TA sensor was prepared and allowed simple detection.

Green synthesis of thiocyanate functionalized carbon quantum dots as a fast and sensitive turn-on fluorescent probe for ascorbic acid detection

Green synthesis of thiocyanate functionalized carbon quantum dots as a fast and sensitive turn-on fluorescent probe for ascorbic acid detection

A highly sensitive turn-on fluorescent probe for real-time detecting hypochlorite and its application in living cells

It is very necessary to develop real-time, highly sensitive and selective fluorescent probes for hypochlorite (ClO−) in living cells owing to hypochlorite's important role in pathological and physiological processes and its short life. Herein, a pyrene Schiff's base derivative was successfully developed for real-time (within seconds), highly sensitive detecting ClO− with a low detection limit (5.7 nM) and wide pH range (4.0–11.0) based on nucleophilic addition and subsequent hydrolysis mechanism. The probe has aggregation-induced emission properties and emits yellow fluorescence (544 nm) in PBS solution, while it exhibits blue fluorescence in other organic solvents (426 nm (THF) - 460 nm (MeOH)). The probe can be used to response ClO− in A549 cells with low cytotoxicity, a good cell membranes penetration and good biocompatibility. Cell uptake experiment indicates that probe getting into the cells is energy-dependent and is not attributed to endocytosis. Moreover, the probe is successfully used in real water sample to detect ClO− and it can be expected to be applied to ClO− participated biological and pathological functions in biological systems.

Visualization of sulfur mustard in living cells and whole animals with a selective and sensitive turn-on fluorescent probe

Sulfur mustard is a potent blister agent and one of the most harmful chemical warfare agents. To explore the toxicokinetics and biodistribution of SM, a reliable detection method for monitoring sulfur mustard would be indispensable. We describe the design, synthesis and application of a selective and sensitive turn-on fluorescent probe for sulfur mustard detection. A good linear relationship between fluorescence emission intensity and SM concentration was observed. The probe, SM-Flu, was applied to the determination and imaging of sulfur mustard in living cells and Aurelia coerulea polyps. With SM-Flu, concentration and time profiles for SM in mouse brain after exposure to SM were first measured.

A highly selective and sensitive turn-on fluorescent probe for copper(II) ion with a large Stokes shift

A new Schiff-base fluorescent probe 1 for the selective detection of Cu2+ has been synthesized by a simple one-step reaction of 1,3,3-trimethyl-2-(formylmethylene)indoline and diaminomaleonitrile. The probe 1 exhibited strong fluorescence enhancement with a large Stokes shift (146nm) upon addition of Cu2+ and showed an excellent selectivity in the presence of competitive ions. The detection limit was found to be 6.18×10−8mol/L. The 1:1 binding mode of 1 with Cu2+ was supported by the Job's plot, 1H NMR and ESI-mass spectrometry analysis. Moreover, 1 also had the ability to quantify Cu2+ in actual water samples.

A rapid and sensitive turn-on fluorescent probe for ascorbic acid detection based on carbon dots–MnO2 nanocomposites

A rapid turn-on fluorescent probe is proposed for the sensitive and specific determination of ascorbic acid based on carbon dots–MnO2 nanocomposites.

Curcumin-Based "Enhanced SNAr" Promoted Ultrafast Fluorescent Probe for Thiophenols Detection in Aqueous Solution and in Living Cells.

We report herein a highly selective and sensitive turn-on fluorescent probe (compound 1) with a fast response time (less than 2 min) for thiophenol detection based on an "enhanced SNAr" reaction between thiophenols and a sulfonyl-ester moiety covalently attach to curcumin. Reaction of 1 in Hepes-MeOH (1:1, v/v, pH 7.4) in the presence of 4-methylthiophenol (MTP) resulted in a remarkable enhancement of the fluorescence. A linear response in the presence of MTP of the relative fluorescent intensity (F - F0) of 1 at 536 nm in the 0-40 μM MTP concentration range was found. A limit of detection (LOD) for the detection of MTP of 26 nM, based on the definition by IUPAC (CDL = 3 Sb/m), was calculated. Probe 1 was applied to monitor and imaging exogenous MTP in live cells and to the detection of MTP in real water samples.

A highly selective and sensitive turn-on fluorescent probe for the detection of holmium ion and its bioimaging

The phenolphthalein aldehyde was synthesized and used to a turn-on fluorescent probe for the detection of holmium ion (Ho3+) in HEPES : DMF = 1 : 1 (v/v pH = 7.4) solution with an excellent selectivity and sensitivity for Ho3+over other metal ions.