First fluorescent photoinduced electron transfer (PET) reagent for hydroperoxides

Swallow-tailed perylene derivative: a new tool for fluorescent imaging of lipid hydroperoxides

A swallow-tailed perylene derivative including a triphenylphosphine moiety was synthesized and applied to the detection and the live-cell imaging of lipid hydroperoxides. The novel probe, named Spy-LHP, reacted rapidly and quantitatively with lipid hydroperoxides to form the corresponding oxide, Spy-LHPOx, which emits extremely strong fluorescence (Phi approximately 1) in the visible range (lambda(em) = 535 nm, 574 nm). Spy-LHP was highly selective for lipid hydroperoxides, and the addition of other reactive oxygen species (ROS) including hydrogen peroxides, hydroxyl radical, superoxide anion, nitric oxide, peroxynitrite, and alkylperoxyl radical, caused no significant increase in the fluorescence intensity. The probe exhibited good localization to cellular membranes and was successfully applied to the confocal laser scanning microscopy (CLSM) imaging of lipid hydroperoxides in live J774A.1 cells, in which lipid peroxidation was proceeded by the stimulation of 2,2-azobis(2-amidinopropane)dihydrochloride (AAPH). These findings establish Spy-LHP as a promising new tool for investigating the physiology of lipid hydroperoxides.

A FRET-based approach to ratiometric fluorescence detection of hydrogen peroxide

We report the synthesis, properties, and biological applications of Ratio-Peroxyfluor-1 (RPF1), a new ratiometric fluorescent reporter for hydrogen peroxide. RPF1 is comprised of a two-fluorophore cassette, where the spectral overlap between coumarin donor and fluoran/fluorescein acceptor partners can be controlled by the chemoselective peroxide-mediated deprotection of boronic ester pendants on the acceptor dye. RPF1 features good selectivity for hydrogen peroxide over a variety of reactive oxygen species, including superoxide and nitric oxide, a ca. 8-fold increase in fluorescence intensity ratio (lambda517/lambda464) upon H2O2 reaction, and excitation and emission profiles in the visible region. Experiments with viable yeast mitochondria show that RPF1 can monitor and quantify endogenous production of H2O2, establishing the potential utility of this approach for probing peroxide biology in living systems.

Novel fluorescent probe for detecting hydroperoxides with strong emission in the visible range

A novel fluorescent probe, a swallow-tailed perylene derivative for detecting hydroperoxides (Spy-HP), containing perylene 3,4,9,10-tetracarboxyl bisimide as the main skeleton in the structure, was developed. Spy-HP reacted rapidly with hydroperoxides such as m-chloroperbenzoic acid (MCPBA) and cumene hydroperoxide to form its oxidized derivative, Spy-HPOx, and emitted an extremely strong fluorescence (phi approximately 1) in the visible range (lambda(ex) = 524 nm and lambda(em) = 535 nm), as the result of canceling the photoinduced electron transfer (PET) effect. The reaction between Spy-HP and hydroperoxides proceeded quantitatively in strict stoichiometry, without being affected by autoxidation or photobleaching. Because of these prominent properties, Spy-HP is expected to be a novel and useful fluorescent probe to 'spy' on hydroperoxides in biosamples.

Boronate-based fluorescent probes for imaging cellular hydrogen peroxide

The syntheses, properties, and biological applications of the Peroxysensor family, a new class of fluorescent probes for hydrogen peroxide, are presented. These reagents utilize a boronate deprotection mechanism to provide high selectivity and optical dynamic range for detecting H2O2 in aqueous solution over similar reactive oxygen species (ROS) including superoxide, nitric oxide, tert-butyl hydroperoxide, hypochlorite, singlet oxygen, ozone, and hydroxyl radical. Peroxyresorufin-1 (PR1), Peroxyfluor-1 (PF1), and Peroxyxanthone-1 (PX1) are first-generation probes that respond to H2O2 by an increase in red, green, and blue fluorescence, respectively. The boronate dyes are cell-permeable and can detect micromolar changes in H2O2 concentrations in living cells, including hippocampal neurons, using confocal microscopy and two-photon microscopy. The unique combination of ROS selectivity, membrane permeability, and a range of available excitation/emission colors establishes the potential value of PR1, PF1, PX1, and related probes for interrogating the physiology and pathology of cellular H2O2.

Simple and Rapid Determination of Hydrogen Peroxide Using Phosphine-based Fluorescent Reagents with Sodium Tungstate Dihydrate

A simple batch method for the fluorometric determination of hydrogen peroxide using phosphine-based fluorescent reagents has been developed. A rapid, mild and selective derivatization reaction was achieved by adding sodium tungstate dihydrate to the reaction mixture of hydrogen peroxide and a phosphine-based fluorescent reagent. When 4-diphenylphosphino-7-methylthio-2,1,3-benzoxadiazole was used as a reagent, the derivatization reaction was completed after 2 min at room temperature. The calibration curve was linear between 12.5 and 500 ng hydrogen peroxide in a 10 microL sample solution. This method is accurate and has potential for on-line applications.

A selective, cell-permeable optical probe for hydrogen peroxide in living cells

We present the synthesis, properties, and biological applications of Peroxyfluor-1 (PF1), a new type of optical probe for intracellular imaging of hydrogen peroxide in living biological samples. PF1 utilizes a boronate deprotection mechanism to provide unprecedented selectivity and optical dynamic range for detecting H2O2 in aqueous solution over similar reactive oxygen species including superoxide, nitric oxide, tert-butyl hydroperoxide, and hydroxyl radical. We further demonstrate the value of this reagent for biological applications by imaging changes in [H2O2] in living mammalian cells.

Fluorescence enhancement by hydroperoxides based on a change in the intramolecular charge transfer character of benzofurazan

Strong fluorescence signals were observed after the reaction of novel reagents with hydroperoxides.

Design and development of a fluorescent probe for monitoring hydrogen peroxide using photoinduced electron transfer

A novel fluorescent probe, 7-hydroxy-2-oxo-N-(2-(diphenylphosphino)ethyl)-2H-chromene-3-carboxamide (DPPEA-HC) was developed for use in monitoring hydrogen peroxide (H2O2) production. DPPEA-HC, which consists of a diphenylphosphine moiety and a 7-hydroxycoumarin moiety, reacts with H2O2 to form DPPEA-HC oxide, which is analogous to the reaction of triphenylphosphine with hydroperoxides such as H2O2 to form triphenylphosphine oxide. Photoinduced electron transfer (PET) was applied in the design of DPPEA-HC. Since the diphenylphosphine moiety and the 7-hydroxycoumarin moiety would act as the PET donor and the acceptor, respectively, it would be expected that DPPEA-HC would rationally cancel the PET process via the formation of DPPEA-HC oxide, based on the calculated energy levels of the donor and the acceptor moieties using the B3LYP/6-31G*//AM1 method. The fluorescence intensity of DPPEA-HC increased on the addition of a H2O2 solution in 100 mM sodium phosphate buffer (pH7.4), as predicted from the energy level calculation and a good correlation between increase in the fluorescence of DPPEA-HC and the concentration of H2O2 was observed. DPPEA-HC was also fluoresced by H2O2, which was enzymatically produced in xanthine/xanthine oxidase/superoxide dismutase (XA/XOD/SOD) system. The increase in the fluorescence of DPPEA-HC in the presence of H2O2 immediately ceased on the addition of catalase (CAT), which catalyzes the disproportionation of H2O2. In addition, DPPEA-HC was found to have a much higher selectivity for H2O2 and a greater resistance to autoxidation than 2',7'-dichlorodihydrofluoresein (DCFH). Time-resolved fluorescence measurements of DPPEA-HC and DPPEA-HC oxide confirmed that the fluorescence off/on switching mechanism of DPPEA-HC is based on the PET on/off control.

Strong red fluorescent probes suitable for detecting hydrogen peroxide generated by mice peritoneal macrophages

This paper reports the synthesis, fluorescence properties, and biological applications of naphthofluorescein disulfonate (NFDS-1), as a red fluorescence imaging probe to detect intracellular H2O2.

Attachment of an Electron-Withdrawing Fluorophore to a Cryptand for Modulation of Fluorescence Signaling

The laterally nonsymmetric aza cryptand synthesized by condensing tris(2-aminoethyl)amine (tren) with tris[2-[(3-(oxomethyl)phenyl)oxy]ethyl]mine readily forms mononuclear inclusion complexes with both transition- and main-group-metal ions. The fluorophore 7-nitrobenz-2-oxa-1,3-diazole is attached to one of the secondary amines, to give an integrated fluorophore-receptor configuration. The fluorophoric system does not show any appreciable emission when excited due to an efficient photoinduced intramolecular electron transfer (PET) from the nitrogen lone pair. When a metal ion enters the cavity, the PET is blocked, causing recovery of fluorescence; Cd(II) gives the highest quantum yield. The fluorophore, with pi-accepting ability, drastically alters the binding property of the cryptand. With perchlorate or tetrafluoroborate salts of Cd(II), the metal ion enters the cavity, causing recovery of fluorescence. However, in the presence of coordinating ions such as Cl-, N3-, and SCN-, the metal ion comes out of the cavity, causing PET to take place once again, and the fluorescence is lost. Thus, translocation of Cd(II) between the inside and outside of the cryptand cavity can lead to a reversible fluorescence on/off situation.

Analytical Chemical Studies on High-Performance Recognition and Detection of Bio-molecules in Life

In order to understand the mechanism for maintaining life of animals based on the search of dynamics of biomolecules, I have developed several sensitive and selective methods for their quantification. Using the methods of derivatization with the developed benzofurazan fluorogenic reagents (4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), ammonium 7-fluoro-2,1,3-benzoxadiazole 4-sulfonate (SBD-F) and etc.) followed by high-performance liquid chromatography (HPLC)--fluorescence detection, a certain kind of biological and clinical importance was demonstrated of chiral bio-molecules (D-amino acids, D-lactic acid and so on), peptides and proteins. The proposed method (derivatization with SBD-F, isolation of the fluorescent proteins by two-dimensional HPLC, enzymatic digestion and identification of the altered proteins by HPLC-mass spectrometry (MS)/MS with database-searching algorithm) for proteomics studies revealed the changed proteins in the islets of Langerhans of the dexamethazone-induced diabetic rats. An importance of catecholamine metabolism on the blood pressure regulation was also suggested by the method of HPLC-chemiluminescence detection of catecholamines and their 3-O-methylmetabolites. A new field of Analytical Chemistry, i.e., Bio-Analytical Chemistry, was also proposed.