Search

A boron dipyrromethene-based fluorescent probe, BODH, has been successfully developed for hypochlorous acid detection based on the HOCl-promoted oxidative removal of the C=N bond in response to the amount of HOCl. The reaction is accompanied by a 6-fold increase in fluorescent quantum yield (from 0.05 to 0.29). The fluorescence intensity of the reaction between HOCl and BODH shows a good linearity in the HOCl concentration range of 1–25 μM with a low detection limit of 205 nM (S/N = 3). Confocal fluorescence microscopy imaging using RAW264.7 cells shows that the new probe, BODH, can be used as an effective fluorescent probe for the detection of HOCl in living cells. [ABSTRACT FROM AUTHOR]

A boron dipyrromethene (BODIPY) derivative (BODTe) with an NTe 2 chelating motif exhibits high selectivity for Hg 2+ detection. Significant fluorescence enhancement was observed with the chemosensor BODTe in the presence of Hg 2+ . However, the metal ions Ag + , Al 3+ , Ca 2+ , Cd 2+ , Co 2+ , Cu 2+ ,Cr 3+ , Fe 2+ , Fe 3+ , Hg 2+ , Mg 2+ , Mn 2+ , Ni 2+ , Pb 2+ , and Zn 2+ produced only minor changes in the fluorescence values of the system. The association constant ( K a ) of Hg 2+ binding for the chemosensor BODTe was found to be 3.84 × 10 3 M −1 , with a detection limit of 19.2 μM. The maximum fluorescence enhancement caused by Hg 2+ binding in the chemosensor BODTe was observed over the pH range of 4.0–10.0. Confocal fluorescence microscopy imaging using RAW 264.7 cells showed that BODTe can be used as an effective fluorescent probe for detecting Hg 2+ in living cells. [ABSTRACT FROM AUTHOR]

Abstract: A new coumarin derivative (MS1) containing an imine moiety and a hydroxyl moiety exhibits an enhanced fluorescence in the presence of Hg2+ ions. Other metal ions Al3+, Ca2+, Co2+, Cr3+, Cu2+, Fe2+, Fe3+, Hg2+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ produced only minor changes in the fluorescence values of MS1. The binding ratio of MS1–Hg2+ complexes was determined from the Job plot to be 1:1. The binding constant (K a) of Hg2+ binding to MS1 was found to be 6.85×103 M−1. The maximum fluorescence enhancement caused by Hg2+ binding to MS1 was observed in the pH range of 6.5–9.0. Confocal fluorescence microscopy imaging using RAW 264.7 cells showed that MS1 could be used as an effective fluorescent probe for detecting Hg2+ in living cells. [Copyright &y& Elsevier]

A new coumarin-derived fluorescent probe (1) exhibited significant fluorescence quenching in the presence of Cu2+ ions. Other metal ions, e.g. Ag+, Ca2+, Cd2+, Co2+, Fe2+, Fe3+, Hg2+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+, produced only minor changes in the fluorescence of chemosensor 1. The binding ratio of the chemosensor–Cu2+ complexes was found to be 2 : 1, according to Job plot experiments. The association constant (Ka) for Cu2+ binding with chemosensor 1 was found to be 9.56 × 109 M−2. The maximum fluorescence quenching caused by Cu2+ binding with chemosensor 1 occurred over a pH range of 5–9. Moreover, fluorescence microscopy experiments showed that chemosensor 1 could be used as a fluorescent probe for detecting Cu2+ in living cells. [ABSTRACT FROM AUTHOR]

Abstract: A new pyrene derivative (1) containing a benzothiazolenhydrazone moiety exhibited high selectivity for Cu2+ detection. In the presence of Cu2+, chemosensor 1 provided significant fluorescence enhancement, while Ag+, Ca2+, Cd2+, Co2+, Fe2+, Fe3+, Hg2+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ metal ions produced only minor changes in fluorescence intensity. The association constant (K a) for Cu2+ binding to 1 had a value of 5.00×108 M−2. The maximum fluorescence enhancement induced by Cu2+ binding to the chemosensor was observed over the range pH 2–8.5. Our fluorescence microscopy experiments demonstrate that chemosensor 1 may have application as a fluorescent probe for detecting Cu2+ in living cells. [Copyright &y& Elsevier]

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

Abstract: A new pyrene derivative (1) containing a diaminomaleonitrile moiety exhibits high selectivity for Cu2+ detection. Significant fluorescence enhancement was observed with chemosensor 1 in the presence of Cu2+. However, the metal ions Ag+, Ca2+, Cd2+, Co2+, Fe2+, Fe3+, Hg2+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ produced only minor changes in fluorescence values for the system. The apparent association constant (K a) of Cu2+ binding in chemosensor 1 was found to be 5.55×103 M−1. The maximum fluorescence enhancement caused by Cu2+ binding in chemosensor 1 was observed over the pH range 5–7.5. [ABSTRACT FROM AUTHOR]

Abstract: A new water-soluble fluorescent chemosensor Fluor-HGGG was synthesized by linking a tetrapeptide histidyl-glycyl-glycyl-glycine (HGGG) with fluorescein via standard solid-phase 9-fluorenylmethoxycarbonyl (Fmoc) chemistry. Significant fluorescence quenching was observed with Fluor-HGGG in the presence of Cu2+. Other metal ions including Ag+, Ca2+, Cd2+, Co2+, Fe2+, Fe3+, Hg2+, Mn2+, Ni2+ and Zn2+ produced only minor changes in fluorescence values for the system. The dissociation constant (K D) of Cu2+ binding in Fluor-HGGG was found to be 37μM. The maximum fluorescence quenching caused by Cu2+ binding in Fluor-HGGG was observed over the pH range 7–7.5. [Copyright &y& Elsevier]

[Display omitted] Scheme 1. Schematic representation for the emission of Trp-CuNCs under different pH in HeLa cells. • Tryptophan stabilized copper nanoclusters (TRP-CuNCs) were synthesized by utilizing eco-friendly aminoacid tryptophan as stabilizing agent and Vitamin-C as reducing agent. • The synthesized cluster exhibits reversible enhancement in emission on moving from pH 9–3 while most of the reported clusters demonstrated turn-on emission in basic pH. • The mechanism of detection was well investigated using control experiments. • Analytical and biological applications was performed using TRP-CuNCs. Aqueous soluble tryptophan templated copper nanoclusters (Trp-CuNCs) are synthesized in one step utilizing eco-friendly precursors and employed in pH sensing as pH acts as an indispensable tool in various fields like chemistry, biology, agriculture etc. Intriguingly, Trp-CuNCs manifested reversible enhancement in emission on moving from basic to acidic pH (9.0–3.0) while turn-on emission in acidic medium is uncommon in reported literatures. The observed peculiarity was due to the presence of indole group in tryptophan which caused aggregation induced quenching (AIQ) in basic medium and it was corroborated by Dynamic Light Scattering (DLS). The role of indole group in aggregation was further substantiated by carrying out control experiments. The type of quenching encountered was identified as static quenching by PL-lifetime experiments. To extend the pragmatic applicability of Trp-CuNCs , bioimaging of HeLa cells under different pH and real sample analysis (water and an antacid product) were performed. [ABSTRACT FROM AUTHOR]

BODIPY functionalized Au nanoparticles (PyBDP-AuNPs) have been developed for detecting cysteine. Gold nanoparticles were prepared by reducing HAuCl 4 with sodium citrate, using PyBDP as the capping agent. Upon addition of cysteine, PyBDP molecules are liberated from the AuNP surface through ligand-exchange displacement based on the strong affinity of Au with the thiol group and result in green fluorescence from PyBDP molecules. This cysteine-induced displacement of PyBDP-AuNPs was monitored by fluorescent spectroscopy with a detection limit of 1.2 μM. Optimal detection of cysteine was achieved over a pH range from 5 to 12. In addition, PyBDP-AuNPs can be used as a fluorescent probe for detecting cysteine in living cells. [ABSTRACT FROM AUTHOR]

We synthesized a new coumarin-based probe TP, containing a disulfide moiety, to detect biothiols in cells. A fluorescence turn-on response is induced by the thiol–disulfide exchange of the probe, with subsequent intramolecular benzothiazolidine ring formation giving rise to a fluorescent product. The probe exhibits an excellent selectivity for cysteine (Cys) and homocysteine (Hcy) over glutathione (GSH) and other amino acids. The fluorescent probe also exhibits a highly sensitive fluorescence turn-on response to Cys and Hcy with detection limits of 0.8 μM for Cys and 0.5 μM for Hcy. In addition, confocal fluorescence microscopy imaging using RAW264.7 macrophages demonstrates that the probe TP could be an efficient fluorescent detector for thiols in living cells. [ABSTRACT FROM AUTHOR]

• PHC displays high specificity for Cu2+ detection with low interference from other metal ions. • PHC has been found to be an effective quantitative detector (LOD, 8 nM) for Cu2+. • PHC can be successfully applied for bio-imaging of Cu2+ in living cells. The development of fluorescent probes to detect trace metal ions in biological samples has been in great need. Herein, a fluorescence turn-on sensor (PHC) was designed for highly selective detection of Cu2+ ions. The probe PHC shows weak fluorescence due to imine isomerization. With Cu2+, a significant blue emission due to Cu2+-induced oxidation of imine to a carboxylate group is observed. The turn-on process is observed with a 63-fold increase of fluorescence quantum yield (from 0.004 to 0.252). The emission intensity has a good linear relation at Cu2+ concentrations of 0–40 μM. The detection limit is estimated as 8 nM (S/N = 3). The maximum emission change induced by Cu2+ is found in the pH range of 6.5–8.0. The probe PHC can be applied in detecting Cu2+ in living cells monitored by confocal fluorescence microscopy imaging. [ABSTRACT FROM AUTHOR]

The need in developing fluorescent probes for trace metal ion detection in biological samples has been an important issue. Herein, a reaction-based fluorescent probe PIC containing a perimidine moiety was designed and synthesized for Hg2+ detection. The probe can selectively distinguish Hg2+ with 42-fold fluorescent enhancement from the other metal ions at physiological pH. This probe can detect Hg2+ with the detection limit of 1.08 μM. The sensor PIC can be applied to real-time detection of Hg2+ in cells with blue emission. Unlabelled Image • PIC contains a perimidine moiety and displays high specificity for Hg2+ detection. • PIC has been found to be an effective quantitative detector (LOD, 1.08 μM) for Hg2+. • PIC can be successfully applied for Hg2+ detection in living cells and zebrafish. [ABSTRACT FROM AUTHOR]

A novel fluorescent switchable [2]rotaxane NIR4 composed of two different molecular stations and rotaxane arms terminated with far-red boron-dipyrromethene (BODIPY) fluorophores and its derivatives were synthesized by CuAAC click chemistry. The molecular shuttling motion of mechanically interlocked molecules (MIMs) could be addressed by the fluorescence signal transduction via distance dependent photo-induced electron transfer process of [2]rotaxane NIR4 triggered by external chemical stimuli of acid/base. Moreover, the flexible arms of triazolium moiety in [2]rotaxane NIR4 and its axle NIR2 exhibited impressive selectivity and sensitivity toward complementary anionic analyte (H 2 PO 4 − ), where the specific mechanical molecular motion was supported by quantum mechanical calculations. The development of [2]rotaxane NIR4 with a high level of structural complexity can be utilized for novel dual sensory detections of acid-base and dihydrogen phosphate (H 2 PO 4 − ) anion. Importantly, the host of NIR2 and [2]rotaxane NIR4 could be applied for the vitro imaging and clarify the distribution of H 2 PO 4 − at subcellular levels. [ABSTRACT FROM AUTHOR]

A new dual chemosensor ( Z )-2-(anthracen-9-ylmethylene)- N -phenylhydrazinecarbothioamide R 1 was synthesized by incorporating a thiourea derivative as a binding unit and an anthracene group as a fluorescence signalling unit. R 1 selectively binds with Cu 2+ and Hg 2+ ions in aqueous medium. R 1 exhibits highly selective recognition towards F − ion and picric acid in organic medium. Fluorescence quenching was observed in case of R 1 with Cu 2+ and Hg 2+ ions over commonly coexistent metal ions. Furthermore, fluorescence imaging experiments of Cu 2+ and Hg 2+ ions in living RAW 264.7 cells demonstrate its value of practical applications in biological systems. [ABSTRACT FROM AUTHOR]

• The first example of NADH responsive two-photon fluorescent probe. • Only it showed the emission signals at 460 nm upon two photon excitations at 860 nm in the presence of NADH/NAD(P)H. • We established cross talk between ROS regulator GSH. • It visualized NADH dependent mitochondrial oxidative phosphorylation cycle. • The probe selectively levelled tumor tissue based on overexpressed NADH. We have developed a two-photon fluorescent indicator (MC 2P) that participates in a redox reaction with NADH to provide a fluorescence signal at 460 nm. The quantum yield of the indicator MC 2P has increased about 26-fold in the presence of NADH. High two-photon efficiency (GM = 80.94) of the indicator MC 2P has considered it as a unique device for assessing NADH expression in live cells without interference from native fluorogenic entities. It rapidly internalized into live cells and showed a considerable fluorescence signal in cancer cells than the immune cells (RAW 264.7). The indicator MC 2P has provided information on the fluctuation of NADH levels depending on the variation of metabolites in the glycolysis pathway. Further, we noticed an increment of NADH level in mitochondrial respiratory cascade by inhibiting NADH-ubiquinone oxo reductase (complex I) using rotenone. On the contrary, uncoupler (CCCP) induced depletion of NADH. The dynamic expression of NAD(P)H has increased for counterbalancing mitochondrial redox potential during ROS (H 2 O 2) suppression by GSH. Finally, in an vivo experiment, the indicator MC 2P has distinguished colon tumor (HT-29 cells) tissue from healthy tissue by providing two-photon fluorescence images. [ABSTRACT FROM AUTHOR]

• A fluorescent probe Lyso-NA has been synthesized for selective detection of HOCl. • The probe Lyso-NA can be applied in sensing exogenous and endogenous HOCl in living cells. • The probe Lyso-NA can detect HOCl quantitatively with a detection limit as low as 13 nM. Hypochlorous acid (HOCl) is involved in numerous cellular processes, such as pathogen response, immune regulation, and anti-inflammation. Consequently, the development of HOCl detection at the cellular level has been an important issue in investigating the dynamic distributions of HOCl. Herein, a fluorescent probe, Lyso-NA , containing a HOCl-reactive aminophenol group and a lysosomal-targeting morpholine group, has been effectively designed for detecting lysosomal HOCl. The reaction of Lyso-NA with HOCl induces the oxidation of aminophenol and accompanied by a 136-fold fluorescence enhancement. The detection limit is found at 13 nM. The fluorescence enhancement is accomplished through the suppression of twisted intramolecular charge transfer (TICT). With morpholine, the probe Lyso-NA shows the great lysosomal targetable ability for imaging endogenous lysosomal HOCl in living cells and tissues by two-photon microscopy, providing an opportunity to monitor HOCl in the lysosomes for understanding its biological functions. [ABSTRACT FROM AUTHOR]

Hypochlorous acid has played several functions in the biological system. However, excess HOCl can cause damage to biomolecules and result in some diseases. Accordingly, a new fluorescent probe, BSP , has been developed for fast recognition of HOCl through the HOCl-induced oxidation of methyl phenyl sulfide to sulfoxide. The reaction of BSP with HOCl caused a 22-fold fluorescence enhancement (quantum yield increase from 0.006 to 0.133). The detection limit of HOCl is found to be 30 nM (S/N = 3). The fluorescence enhancement is due to the suppression of the photo-induced electron transfer from the methyl phenyl sulfide moiety to BODIPY. Eventually, the cellular fluorescence imaging experiment showed that BSP could be effectively used for monitoring HOCl in living cells. Unlabelled Image • A fluorescent probe BSP has been developed for highly selective detection of HOCl. • The probe BSP can be applied in detecting exogenous and endogenous HOCl in living cells. • The probe BSP can quantitatively detect HOCl with a low detection limit 30 nM. [ABSTRACT FROM AUTHOR]