pyrene fluorescence spectroscopy: Topics by Science.gov

Sample records for pyrene fluorescence spectroscopy

Estimation of AOT and SDS CMC in a methanol using conductometry, viscometry and pyrene fluorescence spectroscopy methods

NASA Astrophysics Data System (ADS)

Mitsionis, Anastasios I.; Vaimakis, Tiverios C.

2012-09-01

Critical micelle concentration (CMC) of two anionic surfactants in methanol was estimated using conductometry, viscometry and pyrene fluorescence spectroscopy methods. The surfactants used, were sodium bis(2-ethylhexyl) sulfosuccinate (Aerosol-OT, AOT) and sodium dodecyl sulfate (SDS) dispersed in pure methanol. The CMC determination was evaluated in room temperature. The results have shown nearly similar concentrations.
Synthesis and characterization of novel pyrene-dendronized porphyrins exhibiting efficient fluorescence resonance energy transfer: optical and photophysical properties.

PubMed

Zaragoza-Galán, Gerardo; Fowler, Michael A; Duhamel, Jean; Rein, Regis; Solladié, Nathalie; Rivera, Ernesto

2012-07-31

A novel series of pyrene dendronized porphyrins bearing two and four pyrenyl groups (Py(2)-TMEG1 and Py(4)-TMEG2) were successfully synthesized. First and second generation Fréchet type dendrons (Py(2)-G1OH and Py(4)-G2OH) were prepared from 1-pyrenylbutanol and 3,5-dihydroxybenzyl alcohol. These compounds were further linked to a trimesitylphenylporphyrin containing a butyric acid spacer via an esterification reaction to obtain the desired products. Dendrons and dendronized porphyrins were fully characterized by FTIR and (1)H NMR spectroscopy and their molecular weights were determined by matrix-assisted laser desorption ionization time of flight mass spectrometry. Their optical and photophysical properties were studied by absorption and fluorescence spectroscopies. The formation of dynamic excimers was detected in the pyrene-labeled dendrons, with more excimer being produced in the higher generation dendron. The fluorescence spectra of the pyrene dendronized porphyrins exhibited a significant decrease in the amount of pyrene monomer and excimer emission, jointly with the appearance of a new emission band at 661 nm characteristic of porphyrin emission, an indication that fluorescence resonance energy transfer (FRET) occurred from one of the excited pyrene species to the porphyrin. The FRET efficiency was found to be almost quantitative ranging between 97% and 99% depending on the construct. Model Free analysis of the fluorescence decays acquired with the pyrene monomer, excimer, and porphyrin core established that only residual pyrene excimer formation in the dendrons could occur before FRET from the excited pyrene monomer to the ground-state porphyrin core.
Direct observation of bis(dicarbollyl)nickel conformers in solution by fluorescence spectroscopy: an approach to redox-controlled metallacarborane molecular motors.

PubMed

Safronov, Alexander V; Shlyakhtina, Natalia I; Everett, Thomas A; VanGordon, Monika R; Sevryugina, Yulia V; Jalisatgi, Satish S; Hawthorne, M Frederick

2014-10-06

As a continuation of work on metallacarborane-based molecular motors, the structures of substituted bis(dicarbollyl)nickel complexes in Ni(III) and Ni(IV) oxidation states were investigated in solution by fluorescence spectroscopy. Symmetrically positioned cage-linked pyrene molecules served as fluorescent probes to enable the observation of mixed meso-trans/dl-gauche (pyrene monomer fluorescence) and dl-cis/dl-gauche (intramolecular pyrene excimer fluorescence with residual monomer fluorescence) cage conformations of the nickelacarboranes in the Ni(III) and Ni(IV) oxidation states, respectively. The absence of energetically disfavored conformers in solution--dl-cis in the case of nickel(III) complexes and meso-trans in the case of nickel(IV)--was demonstrated based on spectroscopic data and conformer energy calculations in solution. The conformational persistence observed in solution indicates that bis(dicarbollyl)nickel complexes may provide attractive templates for building electrically driven and/or photodriven molecular motors.
Fluorescence studies on binding of pyrene and its derivatives to humic acid

NASA Astrophysics Data System (ADS)

Nakashima, K.; Maki, M.; Ishikawa, F.; Yoshikawa, T.; Gong, Y.-K.; Miyajima, T.

2007-07-01

Binding of pyrene (PyH) and its derivatives to humic acid (HA) has been studied by fluorescence spectroscopy. The nature of the interaction between HA and pyrene derivatives are extensively investigated by employing three derivatives ranging from anionic to cationic compounds: 1-pyrenebutylic acid (PyA), 1-pyrenemethanol (PyM), and 1-pyrenebutyltrimethylammonium bromide (PyB). Binding constants between HA and PyX (X = H, A, M, B) are obtained by steady-state fluorescence quenching techniques, and it is found that PyB has a markedly large binding constant among the pyrene family. This is attributed to a strong electrostatic interaction between cationic PyB and anionic HA. The result suggests that an electrostatic interaction plays a dominant role in binding of pyrenes to humic acid. The importance of electrostatic interaction was also confirmed by a salt effect on the binding constant. Influence of collisional quenching on the binding constant, which causes overestimation of the binding constant, was examined by time-resolved fluorescence spectroscopy as well as temperature effect in steady-state fluorescence measurements. It is elucidated that collisional quenching does not much bring overestimation into the binding constants.
Self-Assemblies of Single-Walled Carbon Nanotubes through Tunable Tethering of Pyrenes by Dextrin for Rapidly Chiral Sensing

PubMed Central

Wei, Wei-Li; Chen, Qiushui; Li, Haifang; Lin, Jin-Ming

2011-01-01

Pyrene-modified dextrin (Py-Dex) was synthesized via the Schiff base reaction between reducing end of dextrins and 1-aminopyrene, and then self-assemblies of single-walled carbon nanotubes (SWNTs) were fabricated through the tunable tethering of pyrene to SWNTs by dextrin chains. The Py-Dex-SWNTs assemblies were found to be significantly water-soluble because of the synergistic effect of dextrin chains and pyrene moieties. Py-Dex and Py-Dex-SWNTs were adequately characterized by NMR, UV-vis, fluorescence spectroscopy, Raman spectroscopy, matrix-assisted laser desorption/ionization-time of flight mass spectroscopy, and transmission electron microscopy. The tethering effect of dextrin toward pyrene moieties was clearly revealed and was found to be tunable by adjusting the length of dextrin chains. The fluorescence of pyrene moieties was sufficiently quenched by SWNTs with the support of dextrin chains. Furthermore, the Py-Dex-SWNTs assemblies were used for chiral selective sensing by introducing cyclodextrins as chiral binding sites. The rapid chiral sensing was successfully tested for different enantiomers. PMID:21811502
Feasibility of the simultaneous determination of polycyclic aromatic hydrocarbons based on two-dimensional fluorescence correlation spectroscopy

NASA Astrophysics Data System (ADS)

Yang, Renjie; Dong, Guimei; Sun, Xueshan; Yang, Yanrong; Yu, Yaping; Liu, Haixue; Zhang, Weiyu

2018-02-01

A new approach for quantitative determination of polycyclic aromatic hydrocarbons (PAHs) in environment was proposed based on two-dimensional (2D) fluorescence correlation spectroscopy in conjunction with multivariate method. 40 mixture solutions of anthracene and pyrene were prepared in the laboratory. Excitation-emission matrix (EEM) fluorescence spectra of all samples were collected. And 2D fluorescence correlation spectra were calculated under the excitation perturbation. The N-way partial least squares (N-PLS) models were developed based on 2D fluorescence correlation spectra, showing a root mean square error of calibration (RMSEC) of 3.50 μg L- 1 and root mean square error of prediction (RMSEP) of 4.42 μg L- 1 for anthracene and of 3.61 μg L- 1 and 4.29 μg L- 1 for pyrene, respectively. Also, the N-PLS models were developed for quantitative analysis of anthracene and pyrene using EEM fluorescence spectra. The RMSEC and RMSEP were 3.97 μg L- 1 and 4.63 μg L- 1 for anthracene, 4.46 μg L- 1 and 4.52 μg L- 1 for pyrene, respectively. It was found that the N-PLS model using 2D fluorescence correlation spectra could provide better results comparing with EEM fluorescence spectra because of its low RMSEC and RMSEP. The methodology proposed has the potential to be an alternative method for detection of PAHs in environment.
Selective binding of pyrene in subdomain IB of human serum albumin: Combining energy transfer spectroscopy and molecular modelling to understand protein binding flexibility

NASA Astrophysics Data System (ADS)

Ling, Irene; Taha, Mohamed; Al-Sharji, Nada A.; Abou-Zied, Osama K.

2018-04-01

The ability of human serum albumin (HSA) to bind medium-sized hydrophobic molecules is important for the distribution, metabolism, and efficacy of many drugs. Herein, the interaction between pyrene, a hydrophobic fluorescent probe, and HSA was thoroughly investigated using steady-state and time-resolved fluorescence techniques, ligand docking, and molecular dynamics (MD) simulations. A slight quenching of the fluorescence signal from Trp214 (the sole tryptophan residue in the protein) in the presence of pyrene was used to determine the ligand binding site in the protein, using Förster's resonance energy transfer (FRET) theory. The estimated FRET apparent distance between pyrene and Trp214 was 27 Å, which was closely reproduced by the docking analysis (29 Å) and MD simulation (32 Å). The highest affinity site for pyrene was found to be in subdomain IB from the docking results. The calculated equilibrium structure of the complex using MD simulation shows that the ligand is largely stabilized by hydrophobic interaction with Phe165, Phe127, and the nonpolar moieties of Tyr138 and Tyr161. The fluorescence vibronic peak ratio I1/I3 of bound pyrene inside HSA indicates the presence of polar effect in the local environment of pyrene which is less than that of free pyrene in buffer. This was clarified by the MD simulation results in which an average of 5.7 water molecules were found within 0.5 nm of pyrene in the binding site. Comparing the fluorescence signals and lifetimes of pyrene inside HSA to that free in buffer, the high tendency of pyrene to form dimer was almost completely suppressed inside HSA, indicating a high selectivity of the binding pocket toward pyrene monomer. The current results emphasize the ability of HSA, as a major carrier of several drugs and ligands in blood, to bind hydrophobic molecules in cavities other than subdomain IIA which is known to bind most hydrophobic drugs. This ability stems from the nature of the amino acids forming the binding sites of the protein that can easily adapt their shape to accommodate a variety of molecular structures.
Analytical Applications Of High-Resolution Molecular Fluorescence Spectroscopy In Low Temperature Solid Matrices

NASA Astrophysics Data System (ADS)

Hofstraat, Johannes W.; van Zeijl, W. J.; Smedes, F.; Ariese, Freek; Gooijer, Cees; Velthorst, Nel H.; Locher, R.; Renn, Alois; Wild, Urs P.

1989-05-01

High-resolution fluorescence spectroscopy may be used to obtain highly specific, vibrationally resolved spectral signatures of molecules. Two techniques are presented that both make use of low temperature, solid matrices. In Shpol'skii spectroscopy highly resolved spectra are obtained by employing n-alkanes as solvents that form neat crystalline matrices at low temperatures in which the guest molecules occupy well defined substitutional sites. Fluorescence line-narrowing spectroscopy is based on the application of selective (mostly laser-) excitation of the guest molecules. Principles and analytical applications of both techniques will be discussed. Specific attention will be paid to the determination of pyrene in bird meat by means of Shpol'skii spectroscopy and to the possibilities of applying two-dimensional fluorescence line-narrowing spectroscopy.
Opening a spiropyran ring by way of an exciplex intermediate.

PubMed

Benniston, Andrew C; Harriman, Anthony; Howell, Sarah L; Li, Peiyi; Lydon, Donocadh P

2007-02-02

A molecular dyad has been synthesized in which the main chromophore is a 1,4-diethynylated benzene residue terminated with pyrene moieties, this latter unit acting as a single chromophore. A spiropyran group has been condensed to the central phenylene ring so as to position a weak electron donor close to the pyrene unit. Illumination of the pyrene-based chromophore leads to formation of a fluorescent exciplex in polar solvents but pyrene-like fluorescence is observed in nonpolar solvents. The exciplex has a lifetime of a few nanoseconds and undergoes intersystem crossing to the pyrene-like triplet state with low efficiency. Attaching a 4-nitrobenzene group to the open end of the spiropyran unit creates a new route for decay of the exciplex whereby the triplet state of the spiropyran is formed. Nonradiative decay of this latter species results in ring opening to form the corresponding merocyanine species. Rate constants for the various steps have been obtained from time-resolved fluorescence spectroscopy carried out over a modest temperature range. Under visible light illumination, the merocyanine form reverts to the original spiropyran geometry so that the cycle is closed. Energy transfer from the pyrene chromophore to the merocyanine unit leads to an increased rate of ring closure and serves to push the steady-state composition in favor of the spiropyran form.
Fluorescent Polystyrene Microbeads as Invisible Security Ink and Optical Vapor Sensor for 4-Nitrotoluene.

PubMed

Sonawane, Swapnil L; Asha, S K

2016-04-27

Color-tunable solid-state emitting polystyrene (PS) microbeads were developed by dispersion polymerization, which showed excellent fluorescent security ink characteristics along with sensitive detection of vapors of nitro aromatics like 4-nitro toluene (4-NT). The fluorophores pyrene and perylenebisimide were incorporated into the PS backbone as acrylate monomer and acrylate cross-linker, respectively. Solid state quantum yields of 94 and 20% were observed for the pyrene and perylenebisimide, respectively, in the PS/Py and PS/PBI polymers. The morphology and solid state fluorescence was measured by SEM, fluorescence microscopy, and absorbance and fluorescence spectroscopy techniques. The ethanol dispersion of the polymer could be used directly as a fluorescent security "invisible" ink, which became visible only under ultraviolet light. The color of the ink could be tuned depending on the amounts of the pyrene and perylenebisimide incorporated with blue and orange-green for pyrene alone or perylenebisimide alone beads respectively and various shades in between including pure white for beads incorporating both the fluorophores. More than 80% quenching of pyrene emission was observed upon exposure of the polymer in the form of powder or as spin-coated films to the vapors of 4-NT while the emission of perylenebisimide was unaffected. The limit of detection was estimated at 10(-5) moles (2.7 ppm) of 4-NT vapors. The ease of synthesis of the material along with its invisible ink characteristics and nitro aromatic vapor detection opens up new opportunities for exploring the application of these PS-based materials as optical sensors and fluorescent ink for security purposes.
Fluorescence Spectroscopy of Gas-phase Polycyclic Aromatic Hydrocarbons

NASA Technical Reports Server (NTRS)

Thomas, J. D.; Witt, A. N.

2006-01-01

The purpose of this investigation was to produce fluorescence spectra of polycyclic aromatic hydrocarbon (PAH) molecules in the gas-phase for comparison with blue luminescence (BL) emission observed in astrophysical sources Vijh et al. (2004, 2005a,b). The BL occurs roughly from 350 to 450 nm, with a sharp peak near 380 nm. PAHs with three to four rings, e.g. anthracene and pyrene, were found to produce luminescence in the appropriate spectral region, based on existing studies. Relatively few studies of the gas-phase fluorescence of PAHs exist; those that do exist have dealt primarily with the same samples commonly available for purchase such as pyrene and anthracene. In an attempt to understand the chemistry of the nebular environment we also obtained several nitrogen substituted PAHs from our colleagues at NASA Ames. In order to simulate the astrophysical environment we also took spectra by heating the PAHs in a flame. The flame environment counteracts the formation of eximers and permits the spectroscopy of free-flying neutral molecules. Experiments with coal tar demonstrate that fluorescence spectroscopy reveals primarily the presence of the smallest molecules, which are most abundant and which possess the highest fluorescence efficiencies. One gas-phase PAH that seems to fit the BL spectrum most closely is phenanthridine. In view of the results from the spectroscopy of coal tar, a compound containing a mixture of PAHs ranging from small to very large PAH molecules, we can not preclude the presence of larger PAHs in interstellar sources exhibiting BL.
Kinetic analysis of the interaction between poly(amidoamine) dendrimers and model lipid membranes.

PubMed

Tiriveedhi, Venkataswarup; Kitchens, Kelly M; Nevels, Kerrick J; Ghandehari, Hamidreza; Butko, Peter

2011-01-01

We used fluorescence spectroscopy and surface tensiometry to study the interaction between low-generation (G1 and G4) poly(amidoamine) (PAMAM) dendrimers, potential vehicles for intracellular drug delivery, and model lipid bilayers. Membrane association of fluorescently labeled dendrimers, measured by fluorescence anisotropy, increased with increasing size of the dendrimer and with increasing negative charge density in the membrane, indicating the electrostatic nature of the interaction. When the membrane was doped with pyrene-labeled phosphatidyl glycerol (pyrene-PG), pyrene excimer fluorescence demonstrated a dendrimer-induced selective aggregation of negatively charged lipids when the membrane was in the liquid crystalline state. A nonlinear Stern-Volmer quenching of dendrimer fluorescence with cobalt bromide suggested a dendrimer-induced aggregation of lipid vesicles, which increased with the dendrimer's generation number. Surface tensiometry measurements showed that dendrimers penetrated into the lipid monolayer only at subphysiologic surface pressures (<30mN/m). We conclude that the low-generation PAMAM dendrimers associate with lipid membranes predominantly electrostatically, without significantly compromising the bilayer integrity. They bind stronger to membranes with higher fluidity and lower surface pressure, which are characteristic of rapidly dividing cells. Copyright © 2010 Elsevier B.V. All rights reserved.
A Guide to Design Functional Molecular Liquids with Tailorable Properties using Pyrene-Fluorescence as a Probe.

PubMed

Lu, Fengniu; Takaya, Tomohisa; Iwata, Koichi; Kawamura, Izuru; Saeki, Akinori; Ishii, Masashi; Nagura, Kazuhiko; Nakanishi, Takashi

2017-06-13

Solvent-free, nonvolatile, room-temperature alkylated-π functional molecular liquids (FMLs) are rapidly emerging as a new generation of fluid matter. However, precision design to tune their physicochemical properties remains a serious challenge because the properties are governed by subtle π-π interactions among functional π-units, which are very hard to control and characterize. Herein, we address the issue by probing π-π interactions with highly sensitive pyrene-fluorescence. A series of alkylated pyrene FMLs were synthesized. The photophysical properties were artfully engineered with rational modulation of the number, length, and substituent motif of alkyl chains attached to the pyrene unit. The different emission from the excimer to uncommon intermediate to the monomer scaled the pyrene-pyrene interactions in a clear trend, from stronger to weaker to negligible. Synchronously, the physical nature of these FMLs was regulated from inhomogeneous to isotropic. The inhomogeneity, unexplored before, was thoroughly investigated by ultrafast time-resolved spectroscopy techniques. The result provides a clearer image of liquid matter. Our methodology demonstrates a potential to unambiguously determine local molecular organizations of amorphous materials, which cannot be achieved by conventional structural analysis. Therefore this study provides a guide to design alkylated-π FMLs with tailorable physicochemical properties.
A fluorescent probe-labeled Escherichia coli aspartate transcarbamoylase that monitors the allosteric conformational state.

PubMed

West, Jay M; Tsuruta, Hiro; Kantrowitz, Evan R

2004-01-09

A new system has been developed capable of monitoring conformational changes of the 240s loop of aspartate transcarbamoylase, which are tightly correlated with the quaternary structural transition, with high sensitivity in solution. Pyrene, a fluorescent probe, was conjugated to residue 241 in the 240s loop of aspartate transcarbamoylase to monitor changes in conformation by fluorescence spectroscopy. Pyrene maleimide was conjugated to a cysteine residue on the 240s loop of a previously constructed double catalytic chain mutant version of the enzyme, C47A/A241C. The pyrene-labeled enzyme undergoes the normal T to R structural transition, as demonstrated by small-angle x-ray scattering. Like the wild-type enzyme, the pyrene-labeled enzyme exhibits cooperativity toward aspartate, and is activated by ATP and inhibited by CTP at subsaturating concentrations of aspartate. The binding of the bisubstrate analogue N-(phosphonoacetyl)-l-aspartate (PALA), or the aspartate analogue succinate, in the presence of saturating carbamoyl phosphate, to the pyrenelabeled enzyme caused a sigmoidal change in the fluorescence emission. Saturation with ATP and CTP (in the presence of either subsaturating amounts of PALA or succinate and carbamoyl phosphate) caused a hyperbolic increase and decrease, respectively, in the fluorescence emission. The half-saturation values from the fluorescence saturation curves and kinetic saturation curves were, within error, identical. Fluorescence and small-angle x-ray scattering stopped-flow experiments, using aspartate and carbamoyl phosphate, confirm that the change in excimer fluorescence and the quaternary structure change correlate. These results in conjunction with previous studies suggest that the allosteric transition involves both global and local conformational changes and that the heterotropic effect of the nucleotides may be exerted through local conformational changes in the active site by directly influencing the conformation of the 240s loop.
Monitoring benzo(a)pyrene exposure using laser-excited Shpol'skii spectroscopy of benzo(a)pyrene metabolites

NASA Astrophysics Data System (ADS)

Ariese, Freek; Kok, S. J.; Verkaik, M.; Hoornweg, Gerard P.; Gooijer, Cees; Velthorst, Nel H.; Hofstraat, Johannes W.

1993-03-01

Exposure to polycyclic aromatic hydrocarbons (PAHs) is considered a serious threat to the health of animals and humans and should be thoroughly monitored. Next to chemical analysis of PAHs in the various environmental compartments, PAH metabolites in body fluids (e.g., bile and urine) could be measured to determine the actual uptake. Although pyrene is not considered particularly toxic, its metabolite 1-hydroxy pyrene is often used as a biomarker because it is usually found at considerable concentrations and the analysis is relatively simple. As the result of differences in volatility and/or solubility, the uptake of more relevant carcinogens like benzo(a)pyrene may be some orders of magnitude lower and is far more difficult to measure. Determination of benzo(a)pyrene metabolites requires a very selective and sensitive method, and so far these compounds could only be detected after exposure to heavy pollution. In this paper it will be shown how several hydroxy benzo(a)pyrene metabolites are selectively determined using Shpol'skii spectroscopy. With this method, highly resolved fluorescence spectra are obtained upon cooling the sample in a suitable solvent to cryogenic temperatures. When a tunable laser system is employed as an excitation source, sub- femtomole amounts can be detected. Applications of the technique to marine monitoring (benzo(a)pyrene metabolites in fish bile) and to occupational hygienics (benzo(a)pyrene metabolites in workers' urine) are discussed. The data will be compared with 1-hydroxy pyrene concentrations to evaluate the routine use of the latter compound as a biomarker.
Analysis of co-eluted isomers of high-molecular weight polycyclic aromatic hydrocarbons in high performance liquid chromatography fractions via solid-phase nanoextraction and time-resolved Shpol'skii spectroscopy.

PubMed

Wilson, Walter B; Campiglia, Andres D

2011-09-28

We present an accurate method for the determination of isomers of high-molecular weight polycyclic aromatic hydrocarbons co-eluted in HPLC fractions. The feasibility of this approach is demonstrated with two isomers of molecular weight 302 with identical mass fragmentation patterns, namely dibenzo[a,i]pyrene and naphtho[2,3-a]pyrene. Qualitative and quantitative analysis is carried out via laser-excited time-resolved Shpol'skii spectroscopy at liquid helium temperature. Unambiguous identification of co-eluted isomers is based on their characteristic 4.2 K line-narrowed spectra in n-octane as well as their fluorescence lifetimes. Pre-concentration of HPLC fractions prior to spectroscopic analysis is performed with the aid of gold nanoparticles via an environmentally friendly procedure. In addition to the two co-eluted isomers, the analytical figures of merit of the entire procedure were evaluated with dibenzo[a,l]pyrene, dibenzo[a,h]pyrene and dibenzo[a,e]pyrene. The analytical recoveries from drinking water samples varied between 98.2±5.5 (dibenzo[a,l]pyrene) and 102.7±3.2% (dibenzo[a,i]pyrene). The limits of detection ranged from 51.1 ng L(-1) (naphtho[2,3-a]pyrene) to 154 ng L(-1) (dibenzo[a,e]pyrene). The excellent analytical figures of merit associated to its HPLC compatibility makes this approach an attractive alternative for the analysis of co-eluted isomers with identical mass spectra. Copyright © 2011 Elsevier B.V. All rights reserved.
Association to HeLa cells and surface behavior of exogenous gangliosides studied with a fluorescent derivative of GM1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masserini, M.; Giuliani, A.; Palestini, P.

1990-01-23

Cultured HeLa cells were incubated with pyrene-GM1/{sup 3}H-radiolabeled GM1 ganglioside (1:4 M/M) mixtures for various times. The process of association of pyrene-GM1 with cells was qualitatively and quantitatively the same as that of {sup 3}H-GM1. The pyrene-GM1 and {sup 3}H-GM1 proportions in the various forms of association with cells were similar to that of the starting ganglioside mixture. After 2-h incubation, the association of ganglioside with cells was well established whereas almost no metabolic processing had occurred. During a 24-h incubation, pyrene- and {sup 3}H-GM1 underwent similar metabolic processing and gave rise to catabolic (GM2 and GM3) and anabolic (GDla)more » derivatives. Fluorescence spectroscopy experiments carried out with the excimer formation technique on subcellular fractions containing plasma membranes showed that exogenous ganglioside was, in part, associated with the cells in a micellar form removable by trypsin treatment, and in part inserted in a seemingly molecular dispersion. Addition of Ca{sup 2+} salts caused aggregation of the ganglioside, as indicated by the increase of the excimer:monomer fluorescence ratio. The phenomenon was Ca{sup 2+} concentration dependent (maximum at 10 mM), and subsequent addition of EDTA has no effect. The saccharide portion of exogenously incorporated pyrene-GM1 was available to interact with external ligands, as shown by its ability to bind cholera toxin whose addition reduced the collision rate among the ganglioside lipid moieties.« less
Protonation of Excited State Pyrene-1-Carboxylate by Phosphate and Organic Acids in Aqueous Solution Studied by Fluorescence Spectroscopy

PubMed Central

Zelent, Bogumil; Vanderkooi, Jane M.; Coleman, Ryan G.; Gryczynski, Ignacy; Gryczynski, Zygmunt

2006-01-01

Pyrene-1-carboxylic acid has a pK of 4.0 in the ground state and 8.1 in the singlet electronic excited state. In the pH range of physiological interest (pH ∼5–8), the ground state compound is largely ionized as pyrene-1-carboxylate, but protonation of the excited state molecule occurs when a proton donor reacts with the carboxylate during the excited state lifetime of the fluorophore. Both forms of the pyrene derivatives are fluorescent, and in this work the protonation reaction was measured by monitoring steady-state and time-resolved fluorescence. The rate of protonation of pyrene-COO− by acetic, chloroacetic, lactic, and cacodylic acids is a function of ΔpK, as predicted by Marcus theory. The rate of proton transfer from these acids saturates at high concentration, as expected for the existence of an encounter complex. Trihydrogen-phosphate is a much better proton donor than dihydrogen- and monohydrogen-phosphate, as can be seen by the pH dependence. The proton-donating ability of phosphate does not saturate at high concentrations, but increases with increasing phosphate concentration. We suggest that enhanced rate of proton transfer at high phosphate concentrations may be due to the dual proton donating and accepting nature of phosphate, in analogy to the Grotthuss mechanism for proton transfer in water. It is suggested that in molecular structures containing multiple phosphates, such as membrane surfaces and DNA, proton transfer rates will be enhanced by this mechanism. PMID:16920831
Complexation of β-cyclodextrin with dual molecular probes bearing fluorescent and paramagnetic moieties linked by short polyether chains.

PubMed

Mocanu, S; Matei, I; Ionescu, S; Tecuceanu, V; Marinescu, G; Ionita, P; Culita, D; Leonties, A; Ionita, Gabriela

2017-10-18

Electron paramagnetic resonance (EPR) and fluorescence spectroscopies provide molecular-level insights on the interaction of paramagnetic and fluorescent species with the microenvironment. A series of dual molecular probes bearing fluorescent and paramagnetic moieties linked by flexible short polyether chains have been synthesized. These new molecular probes open the possibility to investigate various multi-component systems such as host-guest systems, polymeric micelles, gels and protein solutions by using EPR and fluorescence spectroscopies concertedly. The EPR and fluorescence spectra of these compounds show that the dependence of the rotational correlation time and fluorescence quantum yield on the chain length of the linker is not linear, due to the flexibility of the polyether linker. The quenching effect of the nitroxide moiety on the fluorescence intensity of the pyrene group varies with the linker length and flexibility. The interaction of these dual molecular probes with β-cyclodextrin, in solution and in polymeric gels, was evaluated and demonstrated by analysis of EPR and fluorescence spectra.
Sensitizing of pyrene fluorescence by β-cyclodextrin-modified TiO2 nanoparticles.

PubMed

Shown, Indrajit; Ujihara, Masaki; Imae, Toyoko

2010-12-15

TiO(2) nanoparticles were synthesized by hydrolysis of tetraisopropyl orthotitanate in an aqueous solution of cyclodextrin. The β-cyclodextrin-modified spherical TiO(2) nanoparticles were water-dispersible and had an average particle diameter of 4.4 ± 1 nm. Pyrene fluorescence was enhanced by increasing the concentration of β-cyclodextrin-modified TiO(2) nanoparticle and the sensitization effect was triply stronger than the case of the β-cyclodextrin only. The increase in a concentration of host (β-cyclodextrin) changes its microenvironment for guest (pyrene), that is, the interaction of pyrene with apolar cavity of β-cyclodextrin increases, resulting in enhancement of fluorescence. The sensitization behavior of pyrene fluorescence in the presence of TiO(2) nanoparticles occurs from the increase in the extinction coefficient of pyrene, demonstrating the charge transfer between pyrene and metal oxide nanoparticle. Crown Copyright © 2010. Published by Elsevier Inc. All rights reserved.

SYNCHRONOUS FLUOROMETRIC MEASUREMENT OF METABOLITES OF POLYCYCLIC AROMATIC HYDROCARBONS IN THE BILE OF BROWN BULLHEAD

EPA Science Inventory

A synchronous fluorescent spectroscopy (SFS) method was developed to measure pyrene-type metabolites in the bile of brown bullhead (Ameiurus nebulosus) and to estimate the exposure of fish to PAHs in four Lake Erie tributaries collected in the spring and fall of 1990 and 1991. Fo...
Cofilin and DNase I affect the conformation of the small domain of actin.

PubMed Central

Dedova, Irina V; Dedov, Vadim N; Nosworthy, Neil J; Hambly, Brett D; dos Remedios, Cris G

2002-01-01

Cofilin binding induces an allosteric conformational change in subdomain 2 of actin, reducing the distance between probes attached to Gln-41 (subdomain 2) and Cys-374 (subdomain 1) from 34.4 to 31.4 A (pH 6.8) as demonstrated by fluorescence energy transfer spectroscopy. This effect was slightly less pronounced at pH 8.0. In contrast, binding of DNase I increased this distance (35.5 A), a change that was not pH-sensitive. Although DNase I-induced changes in the distance along the small domain of actin were modest, a significantly larger change (38.2 A) was observed when the ternary complex of cofilin-actin-DNase I was formed. Saturation binding of cofilin prevents pyrene fluorescence enhancement normally associated with actin polymerization. Changes in the emission and excitation spectra of pyrene-F actin in the presence of cofilin indicate that subdomain 1 (near Cys-374) assumes a G-like conformation. Thus, the enhancement of pyrene fluorescence does not correspond to the extent of actin polymerization in the presence of cofilin. The structural changes in G and F actin induced by these actin-binding proteins may be important for understanding the mechanism regulating the G-actin pool in cells. PMID:12023237
Fluorimetric study of the mechanism of molecular association in aqueous solutions of polymethacrylic acid and sodium dodecylbenzenesulfonate

NASA Astrophysics Data System (ADS)

Sachko, A. V.; Zakordonskii, V. P.; Voloshinovskii, A. S.

2013-03-01

Fluorescent spectroscopy is used to investigate the processes of intermolecular association in mixed solutions of polymethacrylic acid (PMAA) and anionic sodium dodecylbenzenesulfonate (SDBS). We propose a model for describing the stage-by-stage mechanism of association processes and conclude that the nature of intermolecular associates depends on the PMAA-SDBS concentration ratio in the solution. Studying the kinetics of fluorescence decay reveals the simultaneous existence of two types of formations capable of pyrene solubilization.
Binding of polarity-sensitive hydrophobic ligands to erythroid and nonerythroid spectrin: fluorescence and molecular modeling studies.

PubMed

Patra, Malay; Mitra, Madhurima; Chakrabarti, Abhijit; Mukhopadhyay, Chaitali

2014-01-01

We have used three polarity-sensitive fluorescence probes, 6-propionyl 2-(N,N-dimethyl-amino) naphthalene (Prodan), pyrene and 8-anilino 1-naphthalene sulphonic acid, to study their binding with erythroid and nonerythroid spectrin, using fluorescence spectroscopy. We have found that both bind to prodan and pyrene with high affinities with apparent dissociation constants (Kd) of .50 and .17 μM, for prodan, and .04 and .02 μM, for pyrene, respectively. The most striking aspect of these bindings have been that the binding stoichiometry have been equal to 1 in erythroid spectrin, both in dimeric and tetrameric form, and in tetrameric nonerythroid spectrin. From an estimate of apparent dielectric constants, the polarity of the binding site in both erythroid and nonerythroid forms have been found to be extremely hydrophobic. Thermodynamic parameters associated with such binding revealed that the binding is favored by positive change in entropy. Molecular docking studies alone indicate that both prodan and pyrene bind to the four major structural domains, following the order in the strength of binding to the Ankyrin binding domain > SH3 domain > Self-association domain > N-terminal domain of α-spectrin of both forms of spectrin. The binding experiments, particularly with the tetrameric nonerythroid spectrin, however, indicate more toward the self association domain in offering the unique binding site, since the binding stoichiometry have been 1 in all forms of dimeric and tetrameric spectrin, so far studied by us. Further studies are needed to characterize the hydrophobic binding sites in both forms of spectrin.
Interaction of Benzo(a)pyrene with the natural organic matter of soil using three-dimensional (3-D) fluorescence spectroscopy with Parallel Factor Analysis

NASA Astrophysics Data System (ADS)

El Fallah, Rawa

2017-04-01

Benzo(a)pyrene (BaP) is a polycyclic aromatic hydrocarbon arising mainly from the incomplete combustion of organic material. It is toxic and has mutagenic and carcinogenic properties. It is classified as a priority pollutant by The United States Environmental Protection Agency (US-EPA). After it's emission in the atmosphere, and due to its physico-chemical properties, BaP will be deposited in the soil. Its aromaticity gives it the capacity to be studied by fluorescence spectroscopy so that of the Natural Organic Matter (NOM). In this study we used fluorescence excitation-emission-matrix (FEEM) with Parallel Factor analysis (PARAFAC) to study the interaction between NOM of soil and BaP. Soil sample was treated with Tetrasodium pyrophosphate along with Sodium hydroxide to obtain the Humic Substances, which afterwards were physically fractioned under acidic pH into solid Humic Acid and liquid Fulvic Acid. Three concentrations of BaP solution were added to each soil fraction. We compared the results of PARAFAC analysis of the samples containing BaP and the original NOM fractions. In the samples containing BaP, four fluorophores (components) were found, the fourth identified as BaP. Out of the three other fluorophores characteristic of NOM, two were found similar in all NOM fractions whereas only one fluorophore had some variations in its spectral characteristics. The presence of BaP changed the fluorescence of NOM. These modifications were depending on the type of soil fraction.
UVA radiation induced ultrafast electron transfer from a food carcinogen benzo[a]pyrene to organic molecules, biological macromolecules, and inorganic nano structures.

PubMed

Banerjee, Soma; Sarkar, Soumik; Lakshman, Karthik; Dutta, Joydeep; Pal, Samir Kumar

2013-04-11

Reactions involving electron transfer (ET) and reactive oxygen species (ROS) play a pivotal role in carcinogenesis and cancer biochemistry. Our present study emphasizes UVA radiation induced ET reaction as one of the key aspects of a potential carcinogen, benzo[a]pyrene (BP), in the presence of a wide variety of molecules covering organic p-benzoquinone (BQ), biological macromolecules like calf-thymus DNA (CT-DNA), human serum albumin (HSA) protein, and inorganic zinc oxide (ZnO) nanorods (NRs). Steady-state and picosecond-resolved fluorescence spectroscopy have been used to monitor such ET reactions. Physical consequences of BP association with CT-DNA have been investigated through temperature-dependent circular dichroism (CD) spectroscopy. The temperature-dependent steady-state, picosecond-resolved fluorescence lifetime and anisotropy studies reveal the effect of temperature on the perturbation of such ET reactions from BP to biological macromolecules, highlighting their temperature-dependent association. Furthermore, the electron-donating property of BP has been corroborated by measuring wavelength-dependent photocurrent in a BP-anchored ZnO NR-based photodevice, offering new physical insights for the carcinogenic study of BP.
Pyrene As a New Detector for Determining the Composition of Silver Nanoparticle Dispersions in Aqueous Solutions

NASA Astrophysics Data System (ADS)

Romanovskaya, G. I.; Kazakova, S. Yu.; Koroleva, M. V.; Zuev, B. K.

2018-03-01

It is proposed that the fluorescence of monomeric molecules of pyrene in solid matrices or in concentrated micellar solutions be used as a detector for determining the compositional homogeneity of silver nanoparticle (NP) dispersions in aqueous solutions synthesized in different ways. It is found that the morphology of silver NPs affects the change in the fluorescence intensity of monomeric molecules of pyrene in a certain (violet or blue) region of the pyrene optical spectrum. The observed phenomenon is attributed to the resonance of electronic transitions in the monomeric molecules of pyrene in regions with plasmon oscillations in silver nanoparticles. A new way of obtaining fluorescent silver NPs is found.
Time-resolved fluorescence spectroscopy for chemical sensors

NASA Astrophysics Data System (ADS)

Draxler, Sonja; Lippitsch, Max E.

1996-07-01

A family of sensors is presented with fluorescence decay-time measurements used as the sensing technique. The concept is to take a single fluorophore with a suitably long fluorescence decay time as the basic building block for numerous different sensors. Analyte recognition can be performed by different functional groups that are necessary for selective interaction with the analyte. To achieve this, the principle of excited-state electron transfer is applied with pyrene as the fluorophore. Therefore the same instrumentation based on a small, ambient air-nitrogen laser and solid-state electronics can be used to measure different analytes, for example, oxygen, pH, carbon dioxide, potassium, ammonium, lead, cadmium, zinc, and phosphate.
Microenvironmental Effect of 2'-O-(1-Pyrenylmethyl)uridine Modified Fluorescent Oligonucleotide Probes on Sensitive and Selective Detection of Target RNA.

PubMed

Imincan, Gülnur; Pei, Fen; Yu, Lijia; Jin, Hongwei; Zhang, Liangren; Yang, Xiaoda; Zhang, Lihe; Tang, XinJing

2016-04-19

2'-O-(1-Pyrenylmethyl)uridine modified oligoribonucleotides provide highly sensitive pyrene fluorescent probes for detecting specific nucleotide mutation of RNA targets. To develop more stable and cost-effective oligonucleotide probes, we investigated the local microenvironmental effects of nearby nucleobases on pyrene fluorescence in duplexes of RNAs and 2'-O-(1-pyrenylmethyl)uridine modified oligonucleotides. By incorporation of deoxyribonucleotides, ribonucleotides, 2'-MeO-nucleotides and 2'-F-nucleotides at both sides of 2'-O-(1-pyrenylmethyl)uridine (U(p)) in oligodeoxynucleotide probes, we synthesized a series of pyrene modified oligonucleotide probes. Their pyrene fluorescence emission spectra indicated that only two proximal nucleotides have a substantial effect on the pyrene fluorescence properties of these oligonucleotide probes hybridized with target RNA with an order of fluorescence sensitivity of 2'-F-nucleotides > 2'-MeO-nucleotides > ribonucleotides ≫ deoxyribonucleotides. While based on circular dichroism spectra, overall helix conformations (either A- or B-form) of the duplexes have marginal effects on the sensitivity of the probes. Instead, the local substitution reflected the propensity of the nucleotide sugar ring to adopt North type conformation and, accordingly, shifted their helix geometry toward a more A-type like conformation in local microenvironments. Thus, higher enhancement of pyrene fluorescence emission favored local A-type helix structures and more polar and hydrophobic environments (F > MeO > OH at 2' substitution) of duplex minor grooves of probes with the target RNA. Further dynamic simulation revealed that local microenvironmental effect of 2'-F-nucleotides or ribonucleotides was enough for pyrene moiety to move out of nucleobases to the minor groove of duplexes; in addition, 2'-F-nucleotide had less effect on π-stack of pyrene-modified uridine with upstream and downstream nucleobases. The present oligonucleotide probes successfully distinguished target RNA from single-mutated RNA analyte during an in vitro assay of RNA synthesis.
Fluidity of pea root plasma membranes under altered gravity

NASA Astrophysics Data System (ADS)

Klymchuk, D. O.; Baranenko, V. V.; Vorobyova, T. V.; Dubovoy, V. D.

This investigation aims to determine whether clinorotation 2 rev min of pea Pisum sativum L seedlings induces the alterations in the physical-chemical properties of cellular membranes including the plasma membrane fluidity The last is an important regulator of functional activity of membrane enzymes The plasma membranes were isolated by aqueous two-phase partitioning from roots of 6-day old pea seedlings The membrane fluidity was examined by fluorescence spectroscopy using pyrene probe The plasma membrane vesicles with known protein concentration were added to the incubation buffer to a final concentration of 50 mu g of protein per ml A small amount by 1 mu l of pyrene solution in 2-propanol was added to the incubation mixture to a final probe concentration 5 mu M at constant mixing Fluorescence spectra were measured using a Perkin-Elmer LS-50 spectrofluorometer Perkin-Elmer England Pyrene was excited at 337 nm and fluorescence intensity of monomers I M and excimers I E were measured at 393 and 470 nm respectively The I E I M ratios were 0 081 pm 0 003 and 0 072 pm 0 004 in preparations obtained from clinorotated and the control seedlings respectively This fact indicates that rotation on the clinostat increases the membrane fluidity Compared with controls clinorotated seedlings have also showed a reduced growth and a higher level of total unsaturated fatty acids determined by gas chromatography The factors that influence on the fluidity of membrane lipids in bilayer appear to be the
A novel baseline-correction method for standard addition based derivative spectra and its application to quantitative analysis of benzo(a)pyrene in vegetable oil samples.

PubMed

Li, Na; Li, Xiu-Ying; Zou, Zhe-Xiang; Lin, Li-Rong; Li, Yao-Qun

2011-07-07

In the present work, a baseline-correction method based on peak-to-derivative baseline measurement was proposed for the elimination of complex matrix interference that was mainly caused by unknown components and/or background in the analysis of derivative spectra. This novel method was applicable particularly when the matrix interfering components showed a broad spectral band, which was common in practical analysis. The derivative baseline was established by connecting two crossing points of the spectral curves obtained with a standard addition method (SAM). The applicability and reliability of the proposed method was demonstrated through both theoretical simulation and practical application. Firstly, Gaussian bands were used to simulate 'interfering' and 'analyte' bands to investigate the effect of different parameters of interfering band on the derivative baseline. This simulation analysis verified that the accuracy of the proposed method was remarkably better than other conventional methods such as peak-to-zero, tangent, and peak-to-peak measurements. Then the above proposed baseline-correction method was applied to the determination of benzo(a)pyrene (BaP) in vegetable oil samples by second-derivative synchronous fluorescence spectroscopy. The satisfactory results were obtained by using this new method to analyze a certified reference material (coconut oil, BCR(®)-458) with a relative error of -3.2% from the certified BaP concentration. Potentially, the proposed method can be applied to various types of derivative spectra in different fields such as UV-visible absorption spectroscopy, fluorescence spectroscopy and infrared spectroscopy.
Synthesis, fluorescence properties and the promising cytotoxicity of pyrene-derived aminophosphonates.

PubMed

Lewkowski, Jarosław; Rodriguez Moya, Maria; Wrona-Piotrowicz, Anna; Zakrzewski, Janusz; Kontek, Renata; Gajek, Gabriela

2016-01-01

A large series of variously substituted amino(pyren-1-yl)methylphosphonic acid derivatives was synthesized using a modified aza-Pudovik reaction in 20-97% yields. The fluorescence properties of the obtained compounds were investigated revealing that N-alkylamino(pyren-1-yl)methylphosphonic derivatives are stronger emissive compounds than the corresponding N-aryl derivatives. N-Benzylamino(pyren-1-yl)methylphosphonic acid displayed strong fluorescence (ΦF = 0.68) in phosphate-buffered saline (PBS). The influence of a series of derivatives on two colon cancer cell lines HT29 and HCT116 was also investigated. The most promising results were obtained for N-(4-methoxyphenyl)amino(pyren-1-yl)methylphosphonate, which was found to be cytotoxic for the HCT116 cancer cell line (IC50 = 20.8 μM), simultaneously showing weak toxicity towards normal lymphocytes (IC50 = 230.8 µM).
Molecular Probe Fluorescence Monitoring of Polymerization

NASA Technical Reports Server (NTRS)

Bunton, Patrick

2002-01-01

This project investigated the feasibility of using fluorescence spectroscopy to determine viscosity of polymer/monomer in support of Transient Interfacial Phenomena in Miscible Polymer Systems (TIPMPS). This project will attempt to measure gradient induced flow at a miscible interface during and / or after in-flight polymerization of dodecyl acrylate (lauryl acrylate). Concentration and temperature gradients will be intentionally introduced during polymerization and the resultant fluid flow determined by Particle Imaging Velocimetry (PIV). This report describes an investigation of the feasibility of using fluorescence of a probe molecule to monitor viscosity and/or concentration during and after polymerization. The probe used was pyrene which has been shown to be sensitive to its local environment in methyl methacrylate.
Assessment of bile fluorescence patterns in a tropical fish, Nile tilapia (Oreochromis niloticus) exposed to naphthalene, phenanthrene, pyrene and chrysene using fixed wavelength fluorescence and synchronous fluorescence spectrometry.

PubMed

Pathiratne, A; Hemachandra, C K; Pathiratne, K A S

2010-05-01

Bile fluorescence patterns in Nile tilapia, a potential fish for biomonitoring tropical water pollution were assessed following exposure to selected polycyclic aromatic hydrocarbons (PAHs): naphthalene, phenanthrene, pyrene and chrysene. Non-normalized fixed wavelength fluorescence signals in the fish exposed to these PAHs reflected dose and/or time response relationships of their metabolism. Normalizing signals to biliverdin introduced deviations to these response patterns. The optimal wavelength pairs (excitation/emission) for synchronous fluorescence scanning measurements of bile metabolites of naphthalene, phenanthrene, pyrene and chrysene were identified as 284/326, 252/357, 340/382 and 273/382 respectively. This study supports the use of bile fluorescence in Nile tilapia by fixed wavelength fluorescence and synchronous fluorescence spectrometry with non-normalized data as a simple method for screening bioavailability of these PAHs.
Competition-Mediated Pyrene-Switching Aptasensor: Probing Lysozyme in Human Serum with a Monomer-Excimer Fluorescence Switch

PubMed Central

Huang, Jin; Zhu, Zhi; Bamrungsap, Suwussa; Zhu, Guizhi; You, Mingxu; He, Xiaoxiao; Wang, Kemin; Tan, Weihong

2010-01-01

Lysozyme (Lys) plays crucial roles in the innate immune system, and the detection of Lys in urine and serum has considerable clinical importance. Traditionally, the presence of Lys has been detected by immunoassays; however, these assays are limited by the availability of commercial antibodies and tedious protein modification, and prior sample purification. To address these limitations, we report here the design, synthesis and application of a competition-mediated pyrene-switching aptasensor for selective detection of Lys in buffer and human serum. The detection strategy is based on the attachment of pyrene molecules to both ends of a hairpin DNA strand, which becomes the partially complementary competitor to an anti-Lys aptamer. In the presence of target Lys, the aptamer hybridizes with part of the competitor, which opens the hairpin such that both pyrene molecules are spatially separated. In the presence of target Lys, however, the competitor is displaced from the aptamer by the target, subsequently forming an initial hairpin structure. This brings the two pyrene moieties into close proximity to generate an excimer, which, in turn, results in a shift of fluorescence emission from ca. 400 nm (pyrene monomer) to 495 nm (pyrene excimer). The proposed method for Lys detection showed sensitivity as low as 200 pM and high selectivity in buffer. When measured by steady-state fluorescence spectrum, the detection of Lys in human serum showed a strong fluorescent background, which obscured detection of the excimer signal. However, time-resolved emission measurement (TREM) supported the potential of the method in complex environments with background fluorescence by demonstrating the temporal separation of probe fluorescence emission decay from the intense background signal. We have also demonstrated that the same strategy can be applied to the detection of small biomolecules such as adenosine triphosphate (ATP), sowing the generality of our approach. Therefore, the competition-mediated pyrene-switching aptasensor is promising to have potential for clinical and forensic applications. PMID:21080638
APTS and rGO co-functionalized pyrenated fluorescent nanonets for representative vapor phase nitroaromatic explosive detection

NASA Astrophysics Data System (ADS)

Guo, Linjuan; Zu, Baiyi; Yang, Zheng; Cao, Hongyu; Zheng, Xuefang; Dou, Xincun

2014-01-01

For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (~10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective π-π interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives.For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (~10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective π-π interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives. Electronic supplementary information (ESI) available: Vapor pressure of TNT and its analogues, fluorescence quenching kinetics, fluorescence quenching efficiencies and additional SEM images. See DOI: 10.1039/c3nr04960d
Chlorxanthomycin, a Fluorescent, Chlorinated, Pentacyclic Pyrene from a Bacillus sp.†

PubMed Central

Magyarosy, Andrew; Ho, Jonathan Z.; Rapoport, Henry; Dawson, Scott; Hancock, Joe; Keasling, Jay D.

2002-01-01

A gram-positive Bacillus sp. that fluoresces yellow under long-wavelength UV light on several common culture media was isolated from soil samples. On the basis of carbon source utilization studies, fatty acid methyl ester analysis, and 16S ribosomal DNA analysis, this bacterium was most similar to Bacillus megaterium. Chemical extraction yielded a yellow-orange fluorescent pigment, which was characterized by X-ray crystallography, mass spectrometry, and nuclear magnetic resonance spectroscopy. The fluorescent compound, chlorxanthomycin, is a pentacyclic, chlorinated molecule with the molecular formula C22H15O6Cl and a molecular weight of 409.7865. Chlorxanthomycin appears to be located in the cytoplasm, does not diffuse out of the cells into the culture medium, and has selective antibiotic activity. PMID:12147512
Fluorescent film sensors based on SAMs of pyrene derivatives for detecting nitroaromatics in aqueous solutions

NASA Astrophysics Data System (ADS)

Zhang, Shujuan; Ding, Liping; Lü, Fengting; Liu, Taihong; Fang, Yu

2012-11-01

The detection of nitroaromatics in aqueous solutions by a novel pyrene-functionalized film has been investigated in the present study. The pyrene moieties were attached on the glass surface via a long flexible spacer based on self-assembled monolayer technique. Steady-state fluorescence measurements revealed that these surface-attached pyrene moieties exhibited both monomer and excimer emission. Nitroaromatics such as 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and 2,4,6-trinitrophenol (picric acid) were found to efficiently quench the fluorescence emission of this film. The quenching results demonstrated that the excimer emission of these surface-confined pyrene moieties is more sensitive to the presence of nitroaromatics than the monomer emission. The quenching mechanism was examined through fluorescence lifetime measurement and it revealed that the quenching is static in nature and may be caused by electron transfer from the polycyclic aromatics to the nitroaromatics. Furthermore, the response of the film to nitroaromatics is fast and reversible, and the obtained film shows promising potentials in detecting explosives in aqueous environment.
Pyrene based D-π-A architectures: synthesis, density functional theory, photophysics and electron transfer dynamics.

PubMed

Kathiravan, Arunkumar; Srinivasan, Venkatesan; Khamrang, Themmila; Velusamy, Marappan; Jaccob, Madhavan; Pavithra, Nagaraj; Anandan, Sambandam; Velappan, Kandavelu

2017-01-25

Pyrene derivatives show immense potential as sensitizers for dye-sensitized solar cells (DSCs). Therefore, this work focuses on the impact of π-spacers on the photophysical, electrochemical and photovoltaic properties of pyrene based D-π-A dyes, since the insertion of π-spacers is one of the doable strategies to improve the light harvesting properties of the dye. In this respect, three new pyrene based D-π-A dyes have been synthesized and characterized by 1 H, 13 C NMR, and elemental analyses and EI-MS spectrometry. The selected π-spacers are benzene, thiophene and furan. Compared with a benzene spacer, the introduction of a heterocyclic ring spacer reduces the band gap of the dye and brings about the broadening of the absorption spectra to the longer wavelength region through intramolecular charge-transfer (ICT). Combined experimental and theoretical studies were performed to investigate the ICT process involved in the pyrene derivatives. The profound solvatochromism with increased nonradiative rate constants (k nr ) has been construed in terms of ICT from the pyrene core to rhodanine-3-acetic acid via conjugated π-spacers. Electrochemical data also reveal that the HOMO and LUMO energy levels are fine-tuned by incorporating different π-spacers between pyrene and rhodanine-3-acetic acid. On the basis of the optimized DSC test conditions, the best performance was found for PBRA, in which a benzene group is the conjugated π-spacer. The divergence in the photovoltaic behaviors of these dyes was further explicated by femtosecond fluorescence and electrochemical impedance spectroscopy.
Evaluation of Benzo[a]pyrene in Food from China by High-Performance Liquid Chromatography-Fluorescence Detection

PubMed Central

Chen, Yong-Hong; Xia, En-Qin; Xu, Xiang-Rong; Li, Sha; Ling, Wen-Hua; Wu, Shan; Deng, Gui-Fang; Zou, Zhi-Fei; Zhou, Jing; Li, Hua-Bin

2012-01-01

The occurrence and levels of benzo[a]pyrene in various heat-treated foods from China were evaluated by high-performance liquid chromatography-fluorescence detection. In a total of 119 samples, 105 were found to contain benzo[a]pyrene at levels of 0.03 to 19.75 µg/kg. The benzo[a]pyrene contents in 12 animal source foods were higher than the Chinese maximum permissible level in food (5 µg/kg) and the highest level was 19.75 µg/kg, nearly four times the maximum permissible level. The results revealed a widespread carinogenic public health risk from benzo[a]pyrene in heat-treated foods. The highest benzo[a]pyrene levels were found in animal source samples such as charcoal-grilled and smoked meats, especially pork, beef and sausage, while trace levels of benzo[a]pyrene were present in grain food. Charcoal-grilled vegetables were found to also contain certain levels of benzo[a]pyrene. This study provided new information on benzo[a]pyrene content of a variety of heat-treated foods from China. PMID:23202838

Feasibility of the determination of polycyclic aromatic hydrocarbons in edible oils via unfolded partial least-squares/residual bilinearization and parallel factor analysis of fluorescence excitation emission matrices.

PubMed

Alarcón, Francis; Báez, María E; Bravo, Manuel; Richter, Pablo; Escandar, Graciela M; Olivieri, Alejandro C; Fuentes, Edwar

2013-01-15

The possibility of simultaneously determining seven concerned heavy polycyclic aromatic hydrocarbons (PAHs) of the US-EPA priority pollutant list, in extra virgin olive and sunflower oils was examined using unfolded partial least-squares with residual bilinearization (U-PLS/RBL) and parallel factor analysis (PARAFAC). Both of these methods were applied to fluorescence excitation emission matrices. The compounds studied were benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene and indeno[1,2,3-c,d]-pyrene. The analysis was performed using fluorescence spectroscopy after a microwave assisted liquid-liquid extraction and solid-phase extraction on silica. The U-PLS/RBL algorithm exhibited the best performance for resolving the heavy PAH mixture in the presence of both the highly complex oil matrix and other unpredicted PAHs of the US-EPA list. The obtained limit of detection for the proposed method ranged from 0.07 to 2 μg kg(-1). The predicted U-PLS/RBL concentrations were satisfactorily compared with those obtained using high-performance liquid chromatography with fluorescence detection. A simple analysis with a considerable reduction in time and solvent consumption in comparison with chromatography are the principal advantages of the proposed method. Copyright © 2012 Elsevier B.V. All rights reserved.
Composition and morphology characterization of exopolymeric substances produced by the PAH-degrading fungus of Mucor mucedo.

PubMed

Jia, Chunyun; Li, Xiaojun; Allinson, Graeme; Liu, Changfeng; Gong, Zongqiang

2016-05-01

To explore the role of exopolymeric substances (EPS) in the process of polycyclic aromatic hydrocarbons (PAH) biodegradation, the characteristics of EPS isolated from a PAH-degrading fungus were investigated firstly by spectrometric determination, microscopic observation, Fourier transform-infrared spectroscopy (FT-IR), and three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEM), and then the PAH-degrading ability of isolated EPS was evaluated. The EPS compositions and morphology varied significantly with the extraction methods. EPS were mainly composed of proteins, carbohydrate, and humic-like substances, and the cation exchange resin (CER)-extracted EPS were granular while other EPS samples were all powders. Heating was the most effective treatment method, followed by the CER, centrifugation, and ultrasonication methods. However, 3D-EEM data demonstrated that heating treatment makes the mycelia lyse the most. Overall, therefore, the CER was the best EPS extraction method for Mucor mucedo (M. mucedo). The PAH degradation results indicated that 87 % of pyrene and 81 % of benzo[a]pyrene (B[a]P) were removed by M. mucedo over 12 days and 9 % more pyrene and 7 % more B[a]P were reduced after CER-extracted EPS addition of 465 mg l(-1). The investigation of EPS characterization and EPS enhancing PAH biodegradation is the premise for further in-depth exploration of the role of EPS contribution to PAH biodegradation.
Fluorescent 'two-faced' polymer wafers with embedded pyrene-functionalised gelator nanofibres.

PubMed

Moffat, Jamie R; Smith, David K

2011-11-21

Pyrene-functionalised gelators self-assemble into nano-fibrillar organogels in DMSO/styrene/divinylbenzene mixtures, which when polymerised yield polymer wafers with two distinct faces, only one of which is fluorescent and has embedded gelator nanofibres. This journal is © The Royal Society of Chemistry 2011
Excitation and fluorescence spectra of pyrene cooled in a syupersonic jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borisevich, N.A.; Vodovatov, L.B.; D`yachenko, G.G.

1995-02-01

The excitation and fluorescence spectra of pyrene molecules cooled in a jet are obtained upon excitation into the S{sub 1}, S{sub 2}, S{sub 3}, and S{sub 4} electronic states. Based on the K. Ohno MO/8 model, a new method for calculating frequencies of the in-plane vibrations in the excited electronic states of polycyclic aromatic hydrocarbons is developed. The method is used for a comparitive analysis of the excitation and fluorescence spectra and assignment of the spectral lines. Good agreement between calculations and experimental data are found. The fluorescence spectrum recorded upon excitation into the high-lying electronic states shows a newmore » long-wavelength band that is probably related to pyrene dimers formed in a jet. 12 refs., 4 figs., 2 tabs.« less
Synthesis, fluorescence properties and the promising cytotoxicity of pyrene–derived aminophosphonates

PubMed Central

Rodriguez Moya, Maria; Wrona-Piotrowicz, Anna; Gajek, Gabriela

2016-01-01

Summary A large series of variously substituted amino(pyren-1-yl)methylphosphonic acid derivatives was synthesized using a modified aza-Pudovik reaction in 20–97% yields. The fluorescence properties of the obtained compounds were investigated revealing that N-alkylamino(pyren-1-yl)methylphosphonic derivatives are stronger emissive compounds than the corresponding N-aryl derivatives. N-Benzylamino(pyren-1-yl)methylphosphonic acid displayed strong fluorescence (ΦF = 0.68) in phosphate-buffered saline (PBS). The influence of a series of derivatives on two colon cancer cell lines HT29 and HCT116 was also investigated. The most promising results were obtained for N-(4-methoxyphenyl)amino(pyren-1-yl)methylphosphonate, which was found to be cytotoxic for the HCT116 cancer cell line (IC50 = 20.8 μM), simultaneously showing weak toxicity towards normal lymphocytes (IC50 = 230.8 µM). PMID:27559373
APTS and rGO co-functionalized pyrenated fluorescent nanonets for representative vapor phase nitroaromatic explosive detection.

PubMed

Guo, Linjuan; Zu, Baiyi; Yang, Zheng; Cao, Hongyu; Zheng, Xuefang; Dou, Xincun

2014-01-01

For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (∼10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective π-π interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives.
Pyrene-based fluorescent ambidextrous gelators: scaffolds for mechanically robust SWNT-gel nanocomposites.

PubMed

Mandal, Deep; Kar, Tanmoy; Das, Prasanta Kumar

2014-01-27

With the rapid progress in the development of supramolecular soft materials, examples of low-molecular-weight gelators (LMWGs) with the ability to immobilise both water and organic solvents by the same structural scaffold are very limited. In this paper, we report the development of pyrene-containing peptide-based ambidextrous gelators (AGs) with the ability to efficiently gelate both organic and aqueous solvents. The organo- and hydrogelation efficiencies of these gelators are in the range 0.7-1.1% w/v in various organic solvents and 0.5-5% w/v in water at certain acidic pH values (pH 2.0-4.0). Moreover, for the first time, AGs have been utilised to prepare single-walled carbon-nanotube (SWNT)-included soft nanocomposites in both hydro- and organogel matrices. The influence of different non-covalent interactions such as hydrogen bonding, hydrophobic, π-π and van der Waals interactions in self-assembled gelation has been studied in detail by circular dichroism, FTIR, variable-temperature NMR, 2D NOESY and luminescence spectroscopy. Interestingly, the presence of the pyrene moiety in the structure rendered these AGs intrinsically fluorescent, which was quenched upon successful integration of the SWNTs within the gel. The prepared hydro- and organogels along with their SWNT-integrated nanocomposites are thermoreversible in nature. The supramolecular morphologies of the dried gels and SWNT-gel nanocomposites have been studied by transmission electron microscopy, fluorescence microscopy and polarising optical microscopy, which confirmed the presence of three-dimensional self-assembled fibrillar networks (SAFINs) as well as the integrated SWNTs. Importantly, rheological studies revealed that the inclusion of SWNTs within the ambidextrous gels improved the mechanical rigidity of the resulting soft nanocomposites up to 3.8-fold relative to the native gels. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Use of a fluorescent radiolabeled triacylglycerol as a substrate for lipoprotein lipase and hepatic triglyceride lipase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dousset, N.; Negre, A.; Salvayre, R.

1988-06-01

A fluorescent radiolabeled triacylglycerol has been synthesized by using a fluorescent fatty acid (pyrene decanoic acid) and a radiolabeled oleic acid. This analog of the natural substrate, 1(3)pyrene decanoic-2,3 (1,2)-dioleoyl-sn-glycerol, has been tested as substrate for determining lipoprotein lipase and hepatic triacylglycerol lipase activities in post-heparin plasma. Optimal conditions for the determination of the two post-heparin plasma lipases were similar to those using radiolabeled triolein. Using this substrate, both post-heparin lipases exhibited their characteristic properties (pH optimum and effect of inhibitors) and attacked external ester bonds (1 or 3) containing pyrene decanoic and oleic acids at a similar rate.
A pyrene formulation for fluorometric visualization of latent fingermarks

NASA Astrophysics Data System (ADS)

Kumari Sharma, Kirti; Harsha Kannikanti, Gavash; Ramachandra Rao Baggi, Tulsidas; Rao Vaidya, Jayathirtha

2018-07-01

Present work is conducted to demonstrate the use of pyrene for the development of latent fingermarks. Pyrene formulation with binders can be efficiently used for developing latent fingermarks on porous, non-porous and semi-porous surfaces. The effectiveness of pyrene formulation for the detection of latent fingermarks present on a large variety of objects was systematically and comparatively carried out. To optimize the working formulation, studies were carried out using different pyrene concentrations followed by various substrate study, time dependent study, temperature study, depleted fingermark development and the stability of the proposed formulation. When illuminated at 366 nm, the developed fingermarks showed clear, high contrast primary, secondary and tertiary level ridge details. This work reveals that the fluorescent molecules having high quantum yield are a versatile fluorescent label and can find their applications in forensic latent fingermark development.
Development of pyrene-stacked carbon nanotube-based hybrid: measurement of NO3- ions using fluorescence spectroscopy.

PubMed

Billing, Beant Kaur; Mayank; Agnihotri, Prabhat K; Singh, Narinder

2018-06-08

Non-covalent bonding via π-π stacking is in demand these days because it does not affect the structure of the carbon nanotube (CNT). Herein, a hybrid material was fabricated via π-π stacking between the aromatic rings of carbon nanotubes and a dihydropyrimidone-based pyrene derivative. The developed CNT@pyrene hybrid material was fully characterized using SEM, EDX, TEM, XRD, and FTIR techniques. The hybrid was developed to improve the heat transport in the hybrid solution by anion addition. The emission profile of the developed hybrid was screened against TBA salts of different anions in EtOH-H2O (10-90% v/v) solvent system to identify the anion that can interact with the hybrid. The hybrid exhibited high sensitivity and selectivity towards NO3- ions with 1.5-fold enhancement in fluorescence intensity, while other anions neither showed significant responses nor interfered in the sensor's response. The limit of NO3- ions detection was found to be 8.1 nM, calculated using the 3-sigma method. It was observed that the proposed hybrid sensor showed stable response at different pH and diverse salt concentrations. The binding mechanism was elucidated by DFT-based theoretical calculations. Real sample analysis was performed for the detection of NO3- concentrations in local water bodies with accuracy as high as 95%. Viscosity and thermal conductivity experiments were performed to measure the effect of concentration, temperature, and pH on the NO3- response.
FRET based integrated pyrene-AgNPs system for detection of Hg (II) and pyrene dimer: Applications to environmental analysis

NASA Astrophysics Data System (ADS)

Walekar, Laxman S.; Hu, Peidong; Vafaei Molamahmood, Hamed; Long, Mingce

2018-06-01

The integrated system of pyrene and cetyltrimethyl ammonium bromide (CTAB) capped silver nanoparticles (AgNPs) with a distance (r) of 2.78 nm has been developed for the detection of Hg (II) and pyrene dimer. The interaction between pyrene and AgNPs results in the fluorescence quenching of pyrene due to the energy transfer, whose mechanism can be attributed to the Forster Resonance Energy Transfer (FRET) supported by experimental observation and theoretical calculations. The developed probe shows a highly selective and sensitive response towards Hg (II) probably due to the amalgam formation, which results in the fluorescence recovery (90%) of pyrene and color change of solution from yellowish brown to colorless. The addition of Hg (II) may increase the distance between pyrene and AgNPs undergoes the 'FRET OFF' process. This system gives a selective response towards Hg (II) over other competing metal ions. Under the optimal condition, the system offers good linearity between 0.1 and 0.6 μg mL-1 with a detection limit of 62 ng mL-1. In addition, the system also provides an effective platform for detection of pyrene in its dimer form even at very low concentrations (10 ng mL-1) on the surface of AgNPs. Therefore, it could be used as effective alternatives for the detection of Hg (II) as well as pyrene simultaneously.
Thermal bleaching in single fluorescent molecules under two-photon excitation regime

NASA Astrophysics Data System (ADS)

Chirico, Giuseppe; Cannone, Fabio; Baldini, Giancarlo; Diaspro, Alberto

2003-07-01

Single molecule spectroscopy often requires the immobilization of the molecules onto solid or quasi-solid substrates and the use of relatively high excitation intensity We have studied the fluorescence emission of four common dyes used for bio-imaging studies, rhodamine 6G, fluorescein, pyrene and indo-1 at the single molecule level under two-photon excitation regime. We focus on two-photon excitation thermal effects on the stability of the single molecules, influencing the internal photo-dynamics and the total duration of the fluorescent emission. Single dye molecules, spread on a glass substrate by spin coating, show a constant fluorescence output till a sudden transition to a dark state very close to the background. The bleaching time that is found to vary in the series pyrene, Indo-1, fluorescein and rhodamine 6G from the fastest to the slowest one respectively, has a Gaussian distribution suggesting that bleaching is not due to photo-bleaching. Moreover it shows a correlation to the amount of absorbed power not re-irradiated as fluorescence and to the complexity of the molecule. These observations are interpreted as thermal bleaching where the temperature increase is induced by the two-photon excitation process. This study should be extended to different trapping media of interest in single molecule basic research and applications, such as silica and polyacrylamide gels or nanosctructured polyelectrolyte matrices. We think that the observed behavior and the correlations found to the molecular chemical and physical parameters, may be of some help for the design of molecules with switching on-off behavior of longer duration.
Synthesis and Characterization of Fluorescently Labeled Diblock Copolymers for Location-Specific Measurements of The Glass Transition Temperature

NASA Astrophysics Data System (ADS)

Christie, Dane; Register, Richard; Priestley, Rodney

Interfaces play a determinant role in the size dependence of the glass transition temperature (Tg) of polymers confined to nanometric length scales. Interfaces are intrinsic in diblock copolymers, which, depending on their molecular weight and composition, are periodically nanostructured in the bulk. As a result diblock copolymers are model systems for characterizing the effect of interfaces on Tg in bulk nanostructured materials. Investigating the effect of intrinsic interfaces on Tg in diblock copolymers has remained unexplored due to their small periodic length scale. By selectively incorporating trace amounts of a fluorescent probe into a diblock copolymer, Tg can be characterized relative to the diblock copolymer's intrinsic interface using fluorescence spectroscopy. Here, pyrene is selectively incorporated into the poly(methyl methacrylate) (PMMA) block of lamellar forming diblock copolymers of poly(butyl- b-methyl methacrylate) (PBMA-PMMA). Preliminary results show a correlation of Tg as measured by fluorescence with the onset of Tg as measured by calorimetry in labeled homopolymers of PMMA. This result is consistent with previous characterizations of Tg using fluorescence spectroscopy. In selectively labeled diblock copolymers Tg is found to vary systematically depending on the distance of the probe from the PBMA-PMMA interface. We acknowledge funding from the Princeton Center for Complex Materials, a MRSEC supported by NSF Grant DMR 1420541.
Luminescence of ferrocene-modified pyrene derivatives for turn-on sensing of Cu2 + and anions

NASA Astrophysics Data System (ADS)

Sun, Shuhua; Hu, Wenting; Gao, Hongfang; Qi, Honglan; Ding, Liping

2017-09-01

Detection and identification of metal ions by fluorescent turn-on sensors are challenging due to the quenching effect of most of the tested metal ions. In the present work, three ferrocene-modified pyrene-based probes 2-4 were synthesized to act as turn-on fluorescent sensors for Cu2 +. The measurements of fluorescence quantum yield and fluorescence lifetime reveal that ferrocenyl unit can efficiently reduce the fluorescence emission of pyrene moiety. Steady-state fluorescence measurements find that the three ferrocene-modified fluorophores exhibit selective turn-on responses to Cu2 +. Moreover, this turn-on effect to Cu2 + is highly influenced by the type of the counter ion. It is found that the presence of Cl- or NO3- could realize the turn-on response to Cu2 +, whereas, the presence of SO42 - or Ac- could not induce any fluorescence enhancement to Cu2 +. Control experiments with ferrocene-free pyrene-based probe 1 reveal that the ferrocenyl unit plays the key role in the turn-on response to Cu2 +. The possible mechanism for the turn-on responses is attributed to the oxidation behavior of Cu2 + to the ferrocene unit, which is confirmed by the control experiments with sodium ascorbate. Cyclic voltammetry measurements show that Cu2 + can influence the redox behaviors of ferrocenyl derivatives, which is also highly dependent on the anion of the copper salts. The influence of anion on the turn-on responses to Cu2 + was further used for anion detection and fluorescent logic gate.
Luminescence of ferrocene-modified pyrene derivatives for turn-on sensing of Cu2+ and anions.

PubMed

Sun, Shuhua; Hu, Wenting; Gao, Hongfang; Qi, Honglan; Ding, Liping

2017-09-05

Detection and identification of metal ions by fluorescent turn-on sensors are challenging due to the quenching effect of most of the tested metal ions. In the present work, three ferrocene-modified pyrene-based probes 2-4 were synthesized to act as turn-on fluorescent sensors for Cu 2+ . The measurements of fluorescence quantum yield and fluorescence lifetime reveal that ferrocenyl unit can efficiently reduce the fluorescence emission of pyrene moiety. Steady-state fluorescence measurements find that the three ferrocene-modified fluorophores exhibit selective turn-on responses to Cu 2+ . Moreover, this turn-on effect to Cu 2+ is highly influenced by the type of the counter ion. It is found that the presence of Cl - or NO 3 - could realize the turn-on response to Cu 2+ , whereas, the presence of SO 4 2- or Ac - could not induce any fluorescence enhancement to Cu 2+ . Control experiments with ferrocene-free pyrene-based probe 1 reveal that the ferrocenyl unit plays the key role in the turn-on response to Cu 2+ . The possible mechanism for the turn-on responses is attributed to the oxidation behavior of Cu 2+ to the ferrocene unit, which is confirmed by the control experiments with sodium ascorbate. Cyclic voltammetry measurements show that Cu 2+ can influence the redox behaviors of ferrocenyl derivatives, which is also highly dependent on the anion of the copper salts. The influence of anion on the turn-on responses to Cu 2+ was further used for anion detection and fluorescent logic gate. Copyright © 2017 Elsevier B.V. All rights reserved.
Synthesis and fluorescence emission properties of 1,3,6,8-tetraarylpyrenes

NASA Astrophysics Data System (ADS)

Hu, Jian-Yong; Feng, Xing; Tomiyasu, Hirotsugu; Seto, Nobuyuki; Rayhan, Ummey; Elsegood, Mark R. J.; Redshaw, Carl; Yamato, Takehiko

2013-09-01

Three types of stable pyrene-based highly fluorescence (blue) compounds, 1-, 1,6-bis, 1,8-bis and 1,3,6,8-tetrakis(7-tert-butylpyrenyl)pyrenes and 1,3,6,8-tetrakis[9,9-bis(3-methylbutyl)-9H-fluoren-2-yl]pyrene, were successfully synthesized via a Pd/Cu-catalysed Suzuki cross-coupling reaction of the corresponding bromopyrenes with 7-tert-butyl-1-pyrenylboronic ester or 2-[9,9-bis(3-methylbutyl)-9H-fluoren-2-yl]-4,4,5,5-tetramethyl[1,3,2]dioxaborolane, respectively. All compounds have good solubility in common organic solvents and high thermal stability with melting points up to 270 °C; the exceptions are the isomeric 1,6-bis-, and 1,8-bispyrenyl-substituted pyrenes. All products show high extinction coefficients of absorption (λmax ≈ 349-396 nm) and high quantum yields (λmax ≈ 432-465 nm; Φf ≈ 0.75-0.99) in dichloromethane solution, and emit strong fluorescence in the visible region ranging from deep-blue to pure-blue on increasing the number of substituents. This data suggests that such systems have promise as blue emitters in organic light-emitting device (OLED) applications (OLED = organic light emitting diode). Crystal structures were determined for 1,3,6,8-tetrakis [9,9-bis(3-methylbutyl)-9H-fluoren-2-yl] pyrene and 1,3,6,8-tetrakis(4-methoxyphenyl)pyrene.
A new pyrene based highly sensitive fluorescence probe for copper(II) and fluoride with living cell application.

PubMed

Goswami, Shyamaprosad; Chakraborty, Shampa; Paul, Sima; Halder, Sandipan; Panja, Sukanya; Mukhopadhyay, Subhra Kanti

2014-05-21

A new pyrene based fluorescence probe has been synthesized for fluorogenic detection of Cu(2+) in acetonitrile-aqueous media (7 : 3 CH3CN-HEPES buffer, v/v, at pH 7.5) with bioimaging in both prokaryotic (Candida albicans cells) and eukaryotic (Tecoma stans pollen cells) living cells. The anion recognition properties of the sensor have also been studied in acetonitrile by fluorescence methods which show remarkable sensitivity toward fluoride over other anions examined.
IMMOBILIZATION OF AQUEOUS PYRENE BY DISSOLVED HUMIC ACID (R822832)

EPA Science Inventory

Abstract
Pyrene is frequently used as a fluorescent probe in the study of solution environments. Purging with nitrogen is a common practice for the elimination of oxygen from solutions, but this procedure leads to the loss of pyrene through carry-over in the nitrogen s...
Rapid determination of benzo(a)pyrene in roasted coffee and coffee brew by high-performance liquid chromatography with fluorescence detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Kruijf, N.; Schouten, T.; van der Stegen, G.H.D.

A rapid and reliable analytical method is presented for the determination of trace amounts of benzo(a)pyrene in roasted coffee, coffee brew, and spent grounds. Roasted coffee and spent grounds were extracted with acetone, followed by saponification and cyclohexane extraction. Coffee brew was extracted three times with cyclohexane, and the combined extracts were purified by chromatography on a silica gel column. The extracts were analyzed by HPLC with a 5-..mu..m Vydac reversed-phase 201 TPB 5 column and fluorescence detection under isocratic conditions. The benzo(a)pyrene levels in 55 roasted coffee samples, commercially available in the Netherlands, ranged from not detectable (<0.1 ..mu..g/kg)more » to 0.5 ..mu..g/kg. Coffee brews were prepared by two different methods from an over-roasted coffee sample with an elevated benzo(a)pyrene level of 2 ..mu..g/kg. These brews yielded benzo(a)pyrene contents of approximately 1 ng/L, indicating benzo(a)pyrene extraction yields of about 1% for both coffee preparation methods.« less
Influence of low oxygen tensions and sorption to sediment black carbon on biodegradation of pyrene.

PubMed

Ortega-Calvo, José-Julio; Gschwend, Philip M

2010-07-01

Sorption to sediment black carbon (BC) may limit the aerobic biodegradation of polycyclic aromatic hydrocarbons (PAHs) in resuspension events and intact sediment beds. We examined this hypothesis experimentally under conditions that were realistic in terms of oxygen concentrations and BC content. A new method, based on synchronous fluorescence observations of (14)C-pyrene, was developed for continuously measuring the uptake of dissolved pyrene by Mycobacterium gilvum VM552, a representative degrader of PAHs. The effect of oxygen and pyrene concentrations on pyrene uptake followed Michaelis-Menten kinetics, resulting in a dissolved oxygen half-saturation constant (K(om)) of 14.1 microM and a dissolved pyrene half-saturation constant (K(pm)) of 6 nM. The fluorescence of (14)C-pyrene in air-saturated suspensions of sediments and induced cells followed time courses that reflected simultaneous desorption and biodegradation of pyrene, ultimately causing a quasi-steady-state concentration of dissolved pyrene balancing desorptive inputs and biodegradation removals. The increasing concentrations of (14)CO(2) in these suspensions, as determined with liquid scintillation, evidenced the strong impact of sorption to BC-rich sediments on the biodegradation rate. Using the best-fit parameter values, we integrated oxygen and sorption effects and showed that oxygen tensions far below saturation levels in water are sufficient to enable significant decreases in the steady-state concentrations of aqueous-phase pyrene. These findings may be relevant for bioaccumulation scenarios that consider the effect of sediment resuspension events on exposure to water column and sediment pore water, as well as the direct uptake of PAHs from sediments.

Micelle-assisted signaling of peracetic acid by the oxidation of pyreneboronic acid via monomer-excimer switching.

PubMed

Choi, Jiyoung; Lee, Hyo Jin; Cho, Min Jeoung; Chang, Suk-Kyu

2015-08-15

A simple fluorescent probe for the industrial oxidant peracetic acid (PAA) was investigated. PAA-assisted oxidative conversion of pyrene-1-boronic acid into 1-hydroxypyrene was used as the signaling tool. Pyreneboronic acid was found to display selective signaling behavior, being more responsive to PAA than to other commonly used practical oxidants such as H2O2 and HOCl. The changes in pyrene monomer fluorescence to excimer were used in the quantitative analysis of PAA. When using the surfactant hexadecyltrimethylammonium bromide as a micellar additive, the signaling of PAA was markedly enhanced. Selective fluorescence signaling of PAA by pyrene-1-boronic acid with a detection limit of 1.5×10(-6)M in aqueous environment was successfully achieved. Copyright © 2015 Elsevier B.V. All rights reserved.
The cmc-value of a bolalipid with two phosphocholine headgroups and a C24 alkyl chain: Unusual binding properties of fluorescence probes to bolalipid aggregates.

PubMed

Kordts, Martin; Kerth, Andreas; Drescher, Simon; Ott, Maria; Blume, Alfred

2017-09-01

Bolalipids with a long alkyl chain and two phosphocholine polar groups self-assemble in water into two different types of aggregate structures, namely helical nanofibers at low temperature and two types of micellar aggregates at higher temperature. We tried to determine the critical aggregation concentration (cac) or critical micellar concentration (cmc) of the bolalipid tetracosane-1,24-bis(phosphocholine) (PC-C24-PC) by using different fluorescent probes. The use of pyrene or pyrene derivatives as fluorophores failed, whereas the probes 1,8-ANS and particularly bis-ANS gave consistent results. The structure of the bolalipid aggregates obviously hinders partitioning or binding of pyrene derivatives into the micellar interior, whereas 1,8-ANS and bis-ANS can bind to the surface of the aggregate structures. The observed large increase in fluorescence intensity of bis-ANS indicates that binding to the hydrophobic surface of the aggregates leads to a reduction of the dye mobility. However, binding of bis-ANS is relatively weak, so that the determination of a cac/cmc-value is difficult. Simulations of the intensity curves for PC-C24-PC lead to estimates of the cac/cmc-value of 0.3-1.0×10 -6 M, depending on the structure of the aggregates. Single molecule fluorescence correlation spectroscopy was used to determine the mobility of bis-ANS as a function of concentration of PC-C24-PC. The dye diffusion time and the molecular brightness are lower at low bolalipid concentration, when only free dye is present, and increase at higher concentration when bis-ANS is bound to the aggregates. The experimental cac/cmc-values are higher than those estimated, using an incremental method for the change in Gibbs free energy for micellization with n-alkyl-phosphocholines with only one polar group as a comparison. Apparently, for PC-C24-PC in micellar or fibrous aggregates, more CH 2 groups are exposed to water than in a conventional micelle of an n-alkyl-phosphocholine. Copyright © 2017 Elsevier Inc. All rights reserved.
Location-Specific Measurements of The Glass Transition Temperature in Fluorescently Labeled Diblock Copolymers

NASA Astrophysics Data System (ADS)

Christie, Dane; Register, Richard; Priestley, Rodney

Block copolymers can self-assemble into periodic structures containing a high internal surface area, nanoscale domain periods, and periodically varying composition profiles. Depending on their components, block copolymers may also exhibit variations in their dynamic properties e.g., glass transition temperature (Tg) across the domain period. Measuring the variation of Tg across the domain period of block copolymers has remained a significant challenge due to the nanometer length scale of the domain period. Here we use fluorescence spectroscopy and the selective incorporation of a pyrene-containing methacrylate monomer at various positions along the chain to characterize the distribution of glass transition temperatures across the domain period of an amorphous block copolymer. The pyrene-containing monomer location is determined from the monomer segment distribution calculated using self-consistent field theory. Our model system is a lamella-forming diblock copolymer of poly(butyl methacrylate - b- methyl methacrylate). We show that Tg is asymmetrically distributed across the interface; as the interface is approached, larger gradients in Tg exist in the hard PMMA-rich domain than in the soft PBMA-rich domain. By characterizing Tg of PBMA or PMMA interfacial segments, we show that polymer dynamics at the interface are heterogeneous; there is a 15 K difference in Tg measured between PBMA interfacial segments and PMMA interfacial segments.
Fluorescence enhancement of photoswitchable metal ion sensors

NASA Astrophysics Data System (ADS)

Sylvia, Georgina; Heng, Sabrina; Abell, Andrew D.

2016-12-01

Spiropyran-based fluorescence sensors are an ideal target for intracellular metal ion sensing, due to their biocompatibility, red emission frequency and photo-controlled reversible analyte binding for continuous signal monitoring. However, increasing the brightness of spiropyran-based sensors would extend their sensing capability for live-cell imaging. In this work we look to enhance the fluorescence of spiropyran-based sensors, by incorporating an additional fluorophore into the sensor design. We report a 5-membered monoazacrown bearing spiropyran with metal ion specificity, modified to incorporate the pyrene fluorophore. The effect of N-indole pyrene modification on the behavior of the spiropyran molecule is explored, with absorbance and fluorescence emission characterization. This first generation sensor provides an insight into fluorescence-enhancement of spiropyran molecules.
Polymers imprinted with PAH mixtures--comparing fluorescence and QCM sensors.

PubMed

Lieberzeit, Peter A; Halikias, Konstantin; Afzal, Adeel; Dickert, Franz L

2008-12-01

Molecular imprinting with binary mixtures of different polycyclic aromatic hydrocarbons (PAH) is a tool for design of chemically highly sensitive layers for detection of these analytes. Sensor responses increase by one order of magnitude compared with layers imprinted with one type of template. Detection limits, e.g. for pyrene, reach down to 30 ng L(-1) in water, as could be observed with a naphthalene and pyrene-imprinted polyurethane. Comparing sensor characteristics obtained by QCM and fluorescence reveals different saturation behaviours indicating that, first, single PAH molecules occupy the interaction centres followed by gradual excimer incorporation at higher concentrations finally leading to substantial quenching, when all accessible cavities are occupied. The plateau in the mass-sensitive measurements suggests that up to 80% of the cavities generated in the MIP are re-occupied. Displacement measurements between chrysene and pyrene revealed that for imprinted layers with very high pyrene sensitivities the signals of both PAH are additive, whereas in materials with lower pyrene uptake the two analytes replace each other in the interaction sites of the polymer.
Selective and Sensitive Fluorescent Detection of Picric Acid by New Pyrene and Anthracene Based Copper Complexes.

PubMed

Reddy, Kumbam Lingeshwar; Kumar, Anabathula Manoj; Dhir, Abhimanew; Krishnan, Venkata

2016-11-01

New pyrene and anthracene based copper complexes 4 and 7 respectively were designed, synthesized and characterized. The fluorescence behaviour of both 4 and 7 were evaluated towards nitro aromatics and anions. Both 4 and 7 possess high selectivity for the detection of well-known explosive picric acid (PA) by showing maximum fluorescence affinity. Furthermore, complex 4 showed similar sensing efficiency towards PA at different pH ranges. It was also used for real world applications, as illustrated by the very fast detection of PA from soil samples observed directly by naked eye.
Fluorescence quenching as an indirect detection method for nitrated explosives.

PubMed

Goodpaster, J V; McGuffin, V L

2001-05-01

A novel approach based on fluorescence quenching is presented for the analysis of nitrated explosives. Seventeen common explosives and their degradation products are shown to be potent quenchers of pyrene, having Stern-Volmer constants that generally increase with the degree of nitration. Aromatic explosives such as 2,4,6-trinitrotoluene (2,4,6-TNT) are more effective quenchers than aliphatic or nitramine explosives. In addition, nitroaromatic explosives are found to have unique interactions with pyrene that lead to a wavelength dependence of their Stern-Volmer constants. This phenomenon allows for their differentiation from other nitrated explosives. The fluorescence quenching method is then applied to the determination of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine(HMX), 2,4,6-TNT, nitromethane, and ammonium nitrate in various commercial explosive samples. The samples are separated by capillary liquid chromatography with post-column addition of the pyrene solution and detection by laser-induced fluorescence. The indirect fluorescence quenching method shows increased sensitivity and selectivity over traditional UV-visible absorbance as well as the ability to detect a wider range of organic and inorganic nitrated compounds.
Pyrene absorption can be a convenient method for probing critical micellar concentration (cmc) and indexing micellar polarity.

PubMed

Basu Ray, Gargi; Chakraborty, Indranil; Moulik, Satya P

2006-02-01

The critical micellar concentration (cmc) of both ionic and non-ionic surfactants can be conveniently determined from the measurements of UV absorption of pyrene in surfactant solution. The results on a number of surfactants have agreed with that realized from pyrene fluorescence measurements as well as that obtained following conductometric, tensiometric and calorimetric methods. The absorbance vs [surfactant] profiles for all the major UV spectral peaks of pyrene have been found to be sigmoidal in nature which were analyzed according to Sigmoidal-Boltzmann equation (SBE) to evaluate the cmcs of the studied surfactants. The difference between the initial and the final asymptotes (a(i) and a(f), respectively) of the sigmoidal profile, Delta a = (a(f)-a(i)) and the slope of the sigmoid, S(sig) have been observed to depend on the type of the surfactant. The Delta a has shown a linear correlation with the ratio of the fluorescence intensities of the first and the third vibronic peaks, I1/I3 of pyrene which is considered as a measure of the environmental polarity (herein micellar interior) of the probe (pyrene). Thus, Delta a values have the prospect for use as another index for the estimation of polarity of micellar interior.
Insights into the binding interactions of autochthonous dissolved organic matter released from Microcystis aeruginosa with pyrene using spectroscopy.

PubMed

Yang, Chenghu; Liu, Yangzhi; Zhu, Yaxian; Zhang, Yong

2016-03-15

The autochthonous dissolved organic matter (DOM) released by Microcystis aeruginosa (M. aeruginosa-DOM) during its growth period was characterized by spectroscopy. Furthermore, the relationships between the M. aeruginosa-DOM spectroscopic descriptors and the pyrene binding coefficient (KDOC) values were explored. The results showed that the spectroscopic characteristics of the M. aeruginosa-DOM and the binding properties of pyrene were dynamically changed along with the algae growth. Pearson correlation analysis demonstrated that a higher pyrene KDOC value was observed for the M. aeruginosa-DOM that has a higher humification index (HIX) value, a lower biological index (BIX) value and a lower absorption ratio (E2/E3). The presence of protein-like and long-wavelength-excited humic-like components may impose negative and positive effects on binding of pyrene by the M. aeruginosa-DOM, respectively. Principal component analysis (PCA) further supported that the binding affinity of pyrene may be primarily influenced by the humification degree of the M. aeruginosa-DOM. Copyright © 2016 Elsevier Ltd. All rights reserved.
Supramolecular nanofiber of pyrene-lactose conjugates and its two-photon fluorescence imaging.

PubMed

Sun, Qian; Zhu, Hong-Yu; Wang, Jun-Fang; Chen, Xiao; Wang, Ke-Rang; Li, Xiao-Liu

2018-04-23

A lactose modified pyrene derivative (Py-Lac) was synthesized, with which novel twisted supramolecular nanofibers in diameter about 20 nm were constructed by self-assembly. The nanofibers showed solid-state fluorescence between 400 nm and 650 nm with the maximum emission at 495 nm. Furthermore, its recognition reaction with PNA lectin was investigated by fluorescence spectra and turbidity assays. It is interesting found that the supramolecular assembly as multivalent glycocluster exhibited unique and selectively binding interactions with PNA lectin with the binding constant of 5.74 × 10 6  M -1 . Moreover, compound Py-Lac showed two-photon fluorescence imaging with Hep G2 cells. Copyright © 2018 Elsevier Inc. All rights reserved.
Circularly polarized luminescence of helically assembled pyrene π-stacks on RNA and DNA duplexes.

PubMed

Nakamura, Mitsunobu; Ota, Fuyuki; Takada, Tadao; Akagi, Kazuo; Yamana, Kazushige

2018-05-01

In this report, we describe the circularly polarized luminescence (CPL) of the RNA duplexes having one to four 2'-O-pyrene modified uridines (Upy) and the DNA duplexes having two, four, and six pyrene modified non-nucleosidic linkers (Py). Both the pyrene π-stack arrays formed on the RNA and DNA double helical structures exhibited pyrene excimer fluorescence. In the pyrene-modified RNA systems, the RNA duplex having four Upys gives CPL emission with g lum value of <0.01 at 480 nm. The structure of pyrene stacks on the RNA duplex may be rigidly regulated with increase in the Upy domains, which resulted in the CPL emission. In the DNA systems, the pyrene-modified duplexes containing two and four Pys exhibited CPL emission with g lum values of <0.001 at 505 nm. The pyrene π-stack arrays presented here show CPL emission. However, the g lum values are relatively small when compared with our previous system consisting of the pyrene-zipper arrays on RNA. © 2018 Wiley Periodicals, Inc.
pH-Sensitive polymer assisted self-aggregation of bis(pyrene) in living cells in situ with turn-on fluorescence

NASA Astrophysics Data System (ADS)

Duan, Zhongyu; Gao, Yu-Juan; Qiao, Zeng-Ying; Qiao, Shenglin; Wang, Yongmei; Hou, Chunyuan; Wang, Lei; Wang, Hao

2015-09-01

Supramolecular self-assemblies with various nanostructures in organic and aqueous solutions have been prepared with desired functions. However, in situ construction of self-assembled superstructures in physiological conditions to achieve expected biological functions remains a challenge. Here, we report a supramolecular system to realize the in situ formation of nanoaggregates in living cells. The bis(pyrene) monomers were dispersed inside of hydrophobic domains of pH-sensitive polymeric micelles and delivered to the lysosomes of cells. In the acidic lysosomes, the bis(pyrene) monomers were released and self-aggregated with turn-on fluorescence. We envision this strategy for in situ construction of supramolecular nanostructures in living cells will pave the way for molecular diagnostics in the future.
Determination of 3,6-dinitrobenzo[e]pyrene in surface soil and airborne particles by high-performance liquid chromatography with fluorescence detection.

PubMed

Hasei, Tomohiro; Watanabe, Tetsushi; Hirayama, Teruhisa

2006-11-24

We developed a sensitive analytical method and an efficient clean-up method to quantify 3,6-dinitrobenzo[e]pyrene (3,6-DNBeP) in surface soil and airborne particles. After purification using a silica gel column and two reversed-phase columns, 3,6-DNBeP was reduced to 3,6-diaminobenzo[e]pyrene by a catalyst column and analyzed by high-performance liquid chromatography (HPLC) with a fluorescence detector. 3,6-DNBeP was detected in all of the soil samples and airborne particles examined. The concentration of 3,6-DNBeP in surface soil and airborne particles was determined in the ranges of 347-5007 pg/g of soil and 137-1238 fg/m3, respectively.
Determination of heavy polycyclic aromatic hydrocarbons of concern in edible oils via excitation-emission fluorescence spectroscopy on nylon membranes coupled to unfolded partial least-squares/residual bilinearization.

PubMed

Vásquez, Valeria; Báez, María E; Bravo, Manuel; Fuentes, Edwar

2013-09-01

Seven heavy polycyclic aromatic hydrocarbons (PAHs) of concern on the US Environmental Protection Agency priority pollutant list (benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-c,d]-pyrene) were simultaneously analyzed in extra virgin olive oil. The analysis is based on the measurement of excitation-emission matrices on nylon membrane and processing of data using unfolded partial least-squares regression with residual bilinearization (U-PLS/RBL). The conditions needed to retain the PAHs present in the oil matrix on the nylon membrane were evaluated. The limit of detection for the proposed method ranged from 0.29 to 1.0 μg kg(-1), with recoveries between 64 and 78 %. The predicted U-PLS/RBL concentrations compared favorably with those measured using high-performance liquid chromatography with fluorescence detection. The proposed method was applied to ten samples of edible oil, two of which presented PAHs ranging from 0.35 to 0.63 μg kg(-1). The principal advantages of the proposed analytical method are that it provides a significant reduction in time and solvent consumption with a similar limit of detection as compared with chromatography.
Resistance of bromelain to SDS binding.

PubMed

Bhattacharya, Reema; Bhattacharyya, Debasish

2009-04-01

Interaction of the plant cysteine protease bromelain with SDS has been studied using CD spectroscopy, intrinsic fluorescence emission, extrinsic fluorescence probe pyrene, isothermal calorimetric (ITC) investigations and inhibition of hydrolyzing activity. Results exhibit number of synchronous transitions when plotted against the total SDS concentration. SDS at submicellar level caused conformation change of bromelain leading to a stable entity. ITC and pyrene experiments suggest that the structural modifications below 5 mM, the cmc(app) of SDS solutions containing bromelain, are the result of alterations of solvent hydrophobicity or non-specific weak binding and/or adsorption of SDS monomers. Melting temperature (T(m)) and the free energy change for thermal unfolding (DeltaG(unf)) of the SDS induced conformers was decreased by 5 degrees C and 0.5 kcal/mol respectively, compared to native bromelain. Below 5 mM, SDS caused large decrease in V(max) without affecting K(m) for the substrate Z-Arg-Arg-NHMec. Analysis of kinetic data imply that SDS acts as a partial non-competitive inhibitor since even at 100 mM, the residual activity of bromelain was retained by 3%. Inhibition studies show an IC(50) of 0.55 mM and a high K(i) of 0.145 mM. These demonstrate that bromelain is resistant to SDS binding and denaturation, a property known for beta-sheet rich kinetically stable proteins.
Nitration of benzo[a]pyrene adsorbed on coal fly ash particles by nitrogen dioxide: role of thermal activation.

PubMed

Kristovich, Robert L; Dutta, Prabir K

2005-09-15

Nitration of benzo[a]pyrene (BaP) by nitrogen dioxide (NO2) adsorbed on the surface of thermally activated coal fly ash and model aluminosilicate particles led to the formation of nitrobenzo[a]pyrenes as verified by extraction and gas chromatography/mass spectrometry (GC/MS). In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was utilized to follow the nitration reaction on the surface of zeolite Y. Nitrobenzo[a]pyrene formation was observed along with the formation of nitrous acid and nitrate species. The formation of the BaP radical cation was also observed on thermally activated aluminosilicate particles by electron spin resonance (ESR) spectroscopy. On the basis of GC/MS, DRIFTS, and ESR spectroscopy results, a mechanism of nitration involving intermediate BaP radical cations generated on thermally activated aluminosilicate particles is proposed. These observations have led to the hypothesis that nitration of adsorbed polyaromatic hydrocarbons on coal fly ash by reaction with nitrogen oxides can occur in the smokestack, but with the aging of the fly ash particles, the extent of the nitration reaction will be diminished.
A novel method for the rapid detection of benzo(a)pyrene in liquid milk by dimethyl sulfoxide selectively enhanced synchronous fluorescence spectrometry.

PubMed

Lin, Li-Rong; Luo, He-Dong; Li, Xiu-Ying; Li, Na; Zhou, Na; Jia, Yu-Zhu; Liu, Yi-Hong; Li, Yao-Qun

2014-01-01

Based on the high solubility efficiency and strong fluorescence response of benzo(a)pyrene (BaP) in dimethyl sulfoxide in combination with the high-performance derivative constant-energy synchronous fluorescence spectroscopic (DCESFS) technique, a simple, sensitive and economic method was developed for the determination of BaP in liquid milk. This method comprises ultrasound-assisted solvent extraction, solvent replacement and DCESFS detection. No saponification or other tedious clean-up procedures were needed. The recoveries of BaP in different milk samples were greater than 82%. Detection limits in full- and low-fat milk were 0.03 and 0.04 μg kg(-1), respectively.
Excitation-emission matrix fluorescence spectroscopy in conjunction with multiway analysis for PAH detection in complex matrices.

PubMed

Nahorniak, Michelle L; Booksh, Karl S

2006-12-01

A field portable, single exposure excitation-emission matrix (EEM) fluorometer has been constructed and used in conjunction with parallel factor analysis (PARAFAC) to determine the sub part per billion (ppb) concentrations of several aqueous polycyclic aromatic hydrocarbons (PAHs), such as benzo(k)fluoranthene and benzo(a)pyrene, in various matrices including aqueous motor oil extract and asphalt leachate. Multiway methods like PARAFAC are essential to resolve the analyte signature from the ubiquitous background in environmental samples. With multiway data and PARAFAC analysis it is shown that reliable concentration determinations can be achieved with minimal standards in spite of the large convoluting fluorescence background signal. Thus, rapid fieldable EEM analyses may prove to be a good screening method for tracking pollutants and prioritizing sampling and analysis by more complete but time consuming and labor intensive EPA methods.
Fe3O4@ionic liquid@methyl orange nanoparticles as a novel nano-adsorbent for magnetic solid-phase extraction of polycyclic aromatic hydrocarbons in environmental water samples.

PubMed

Liu, Xiaofei; Lu, Xin; Huang, Yong; Liu, Chengwei; Zhao, Shulin

2014-02-01

A novel nano-adsorbent, Fe3O4@ionic liquid@methyl orange nanoparticles (Fe3O4@IL@MO NPs), was prepared for magnetic solid-phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. The Fe3O4@IL@MO NPs were synthesized by self-assembly of the ionic liquid 1-octadecyl-3-methylimidazolium bromide (C18mimBr) and methyl orange (MO) onto the surface of Fe3O4 silica magnetic nanoparticles, as confirmed by infrared spectroscopy, ultraviolet-visible spectroscopy and superconducting quantum interface device magnetometer. The extraction performance of Fe3O4@IL@MO NPs as a nano-adsorbent was evaluated by using five PAHs, fluorene (FLu), anthracene (AnT), pyrene (Pyr), benzo(a)anthracene (BaA) and benzo(a)pyrene (BaP) as model analytes. Under the optimum conditions, detection limits in the range of 0.1-2 ng/L were obtained by high performance liquid chromatography-fluorescence detection (HPLC-FLD). This method has been successfully applied for the determination of PAHs in environmental water samples by using the MSPE-HPLC-FLD. The recoveries for the five PAHs tested in spiked real water samples were in the range of 80.4-104.0% with relative standard deviations ranging from 2.3 to 4.9%. © 2013 Published by Elsevier B.V.
In situ investigation of the mechanisms of the transport to tissues of polycyclic aromatic hydrocarbons adsorbed onto the root surface of Kandelia obovata seedlings.

PubMed

Li, Ruilong; Zhu, Yaxian; Zhang, Yong

2015-06-01

A novel method for in situ determination of the polycyclic aromatic hydrocarbons (PAHs) adsorbed onto the root surface of Kandelia obovata seedlings was established using laser-induced time-resolved nanosecond fluorescence spectroscopy (LITRF). The linear dynamic ranges for the established method were 1.5-1240ng/spot for phenanthrene, 1.0-1360ng/spot for pyrene and 5.0-1220ng/spot for benzo[a]pyrene. Then, the mechanisms of PAHs transport from the Ko root surface to tissues were investigated. The three-phase model including fast, slow and very slow fractions was superior to the single or dual-phase model to describe the PAHs transport processes. Moreover, the fast fraction of PAHs transport process was mainly due to passive movement, while the slow and very slow fractions were not. Passive movement was the main process of B[a]P adsorbed onto Ko root surface transport to tissues. In addition, the extent of the PAHs transport to Ko root tissues at different salinity were evaluated. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pyrene functionalized molecular beacon with pH-sensitive i-motif in a loop.

PubMed

Dembska, Anna; Juskowiak, Bernard

2015-01-01

In this work, we present a spectral characterization of pH-sensitive system, which combines the i-motif properties with the spatially sensitive fluorescence signal of pyrene molecules attached to hairpin ends. The excimer production (fluorescence max. ∼480 nm) by pyrene labels at the ends of the molecular beacon is driven by pH-dependent i-motif formation in the loop. To illustrate the performance and reversible work of our systems, we performed the experiments with repeatedly pH cycling between pH values of 7.5±0.3 and 6.5±0.3. The sensor gives analytical response in excimer-monomer switching mode in narrow pH range (1.5 pH units) and exhibits high pH resolution (0.1 pH unit). Copyright © 2015 Elsevier B.V. All rights reserved.
THE ROLE OF SELECTED CATIONS IN THE FORMATION OF PSEUDOMICELLES IN AQUEOUS HUMIC ACID (R822832)

EPA Science Inventory

The fluorescence intensity enhancement of a pyrene probe in aqueous humic acid solutions was assessed in terms of added lanthanide and thorium cations. Among the trivalent ions it was found that size played a role, with the small Lu3+ ion producing the greatest increase in pyrene...
Synthesis, characterization and electroluminescence of two highly-twisted non-doped blue light-emitting materials

NASA Astrophysics Data System (ADS)

Gong, Xiaojie; Pan, Yipeng; Xie, Xiang; Tong, Tong; Chen, Runfeng; Gao, Deqing

2018-04-01

Two pyrene derivatives, substituted with 2-methylnaphthalene units on 1,3-position and 1,6-position of pyrene backbones, were designed and synthesized. DFT calculation confirmed that the two molecules were highly twisted and the dihedral angles between pyrene backbone and naphthalene unit were over 80°, being attributed to the steric hindrance of ortho-methyl group and the substitution position of pyrene itself. As a result, the intermolecular aggregation was greatly inhibited in the solid state, being beneficial for suppressing the fluorescence quenching. By analyzing the optical and thermal properties, it was found that the π-π conjugation extension could be adjusted and a balance for high fluorescent efficiency and avoiding quenching at the same time could be reached, which may guide the molecular design in the future. The electroluminescence properties of the non-doped devices were enhanced with the double hole-transporting layers by optimizing the energy level matching. The stable blue EL emission, with the Commission Internationaled'Eclairage (CIEx,y) color coordinates of (0.15, 0.13) and (0.15, 0.11) at 7, 8, 9 and 10 V respectively, was obtained.
Functionalization of diamond nanoparticles using "click" chemistry.

PubMed

Barras, Alexandre; Szunerits, Sabine; Marcon, Lionel; Monfilliette-Dupont, Nicole; Boukherroub, Rabah

2010-08-17

The paper reports on covalent linking of different alkyne-containing (decyne, ethynylferrocene, and N-propargyl-1-pyrenecarboxamide) compounds to azide-terminated nanodiamond (ND) particles. Azide-terminated particles (ND-N(3)) were obtained from amine-terminated nanodiamond particles (ND-NH(2)) through the reaction with 4-azidobenzoic acid in the presence of a carbodiimide coupling agent. Functionalized ND particles with long alkyl chain groups can be easily dispersed in various organic solvents without any apparent precipitation after several hours. The course of the reaction was followed using Fourier transform infrared (FT-IR) spectroscopy, UV/vis spectroscopy, fluorescence, cyclic voltammetry, thermogravimetric analysis (TGA), and particle size measurements. The surface loading of pyrene bearing a terminal acetylene group was found to be 0.54 mmol/g. Because of its gentle nature and specificity, the chemistry developed in this work can be used as a general platform for the preparation of functional nanoparticles for various applications.
Self-assembling surfactant-like peptide A6K as potential delivery system for hydrophobic drugs.

PubMed

Chen, Yongzhu; Tang, Chengkang; Zhang, Jie; Gong, Meng; Su, Bo; Qiu, Feng

2015-01-01

Finding a suitable delivery system to improve the water solubility of hydrophobic drugs is a critical challenge in the development of effective formulations. In this study, we used A6K, a self-assembling surfactant-like peptide, as a carrier to encapsulate and deliver hydrophobic pyrene. Pyrene was mixed with A6K by magnetic stirring to form a suspension. Confocal laser scanning microscopy, transmission electron microscopy, dynamic light scattering, atomic force microscopy, fluorescence, and cell uptake measurements were carried out to study the features and stability of the nanostructures, the state and content of pyrene, as well as the pyrene release profile. The suspension formed contained pyrene monomers trapped in the hydrophobic cores of the micellar nanofibers formed by A6K, as well as nanosized pyrene crystals wrapped up and stabilized by the nanofibers. The two different encapsulation methods greatly increased the concentration of pyrene in the suspension, and formation of pyrene crystals wrapped up by A6K nanofibers might be the major contributor to this effect. Furthermore, the suspension system could readily release and transfer pyrene into living cells. A6K could be further exploited as a promising delivery system for hydrophobic drugs.
Novel functionalized fluorescent polymeric nanoparticles for immobilization of biomolecules

NASA Astrophysics Data System (ADS)

Jain, Swati; Chattopadhyay, Sruti; Jackeray, Richa; Abid, C. K. V. Zainul; Singh, Harpal

2013-07-01

Novel, size controlled fluorescent polymeric nanoparticles (FPNP) were synthesized having acetoacetoxy functionality on the surface for immobilization of biomolecules which can be utilized as biomarkers and labels in fluoroimmunoassays. Core-shell nanoparticles of poly(styrene, St-methyl methacrylate, MMA-acetoacetoxy ethyl methacrylate, AAEM), stabilized by various concentrations of surfactant, sodium lauryl sulphate (SLS), were obtained by facile miniemulsion co-polymerization encapsulated with pyrene molecules in their hydrophobic core. Analytical, spectroscopic and imaging characterization techniques revealed the formation of stable, monodisperse, spherical nano sized particles exhibiting high luminescence properties. Particles with 1% SLS (S1) showed good dispersion stability and fluorescence intensity and were chosen as ideal candidates for further immobilization studies. Steady state fluorescence studies showed 10 times higher fluorescence intensity of S1 nanoparticles than that of pyrene solution in solvent-toluene at the same concentration. Environmental factors such as pH, ionic strength and time were found to have no effect on fluorescence intensity of FPNPs. Surface β-di-ketone groups were utilized for the covalent immobilization of enzyme conjugated antibodies without any activation or pre-treatment of nanoparticles.Novel, size controlled fluorescent polymeric nanoparticles (FPNP) were synthesized having acetoacetoxy functionality on the surface for immobilization of biomolecules which can be utilized as biomarkers and labels in fluoroimmunoassays. Core-shell nanoparticles of poly(styrene, St-methyl methacrylate, MMA-acetoacetoxy ethyl methacrylate, AAEM), stabilized by various concentrations of surfactant, sodium lauryl sulphate (SLS), were obtained by facile miniemulsion co-polymerization encapsulated with pyrene molecules in their hydrophobic core. Analytical, spectroscopic and imaging characterization techniques revealed the formation of stable, monodisperse, spherical nano sized particles exhibiting high luminescence properties. Particles with 1% SLS (S1) showed good dispersion stability and fluorescence intensity and were chosen as ideal candidates for further immobilization studies. Steady state fluorescence studies showed 10 times higher fluorescence intensity of S1 nanoparticles than that of pyrene solution in solvent-toluene at the same concentration. Environmental factors such as pH, ionic strength and time were found to have no effect on fluorescence intensity of FPNPs. Surface β-di-ketone groups were utilized for the covalent immobilization of enzyme conjugated antibodies without any activation or pre-treatment of nanoparticles. Electronic supplementary information (ESI) available: Resulting ATR-FTIR spectrum and procedure to study fluorescence of nanoparticles, effect of particle size, concentration, pH, ionic strength and time on Fl intensity of FPNP. See DOI: 10.1039/c3nr34100c
Solid-state surface luminescence of polycyclic aromatic hydrocarbons adsorbed on cellulose diacetate matrices

NASA Astrophysics Data System (ADS)

Rogacheva, Svetlana M.; Shipovskaya, Anna B.; Volkova, Elena V.; Khurshudyan, Grachia N.; Suska-Malawska, Malgorzata; Gubina, Tamara I.

2018-04-01

The spectral-kinetic characteristics of luminescence of 17 polycyclic aromatic hydrocarbons (PAH) sorbed from a "water-organic solvent" medium on cellulose diacetate (CDA) matrices were studied. A significant increase in the fluorescence signal on the CDA matrix was observed for 13 PAHs in comparison with aqueous solutions. The highest detection sensitivity was found for pyrene, benzo(a)pyrene, and benzo(k)fluoranthene. The fluorescence spectra of two PAH indicator pairs (anthracene-phenanthrene and pyrene-fluoranthene) used to control toxicant emission sources were studied with the simultaneous presence of isomers in the analyte, depending on the excitation wavelength. For both isomer pairs, it has been found that the spectra of their solid-state luminescence overlap insignificantly, the characteristic peaks do not coincide and do not overlap, the sensitivities of detection are close to each other, which makes it possible to consider this technique as promising to control PAH contamination sources.
On-line and in-situ detection of polycyclic aromatic hydrocarbons (PAH) on aerosols via thermodesorption and laser-induced fluorescence spectroscopy.

PubMed

Panne, U; Knöller, A; Kotzick, R; Niessner, R

2000-02-01

A fiber optical sensor system for the determination of polycyclic aromatic hydrocarbons (PAH) on aerosols by laser-induced, time-resolved fluorescence is combined with a thermodesorption device. The sensor system is based on an aerosol flow cell, which is fibre-optically coupled to a pulsed nitrogen laser for excitation and the detection system. Time-resolved fluorescence emission spectra are detected by a monochromator equipped with a photomultiplier and a fast digital storage oscilloscope. The analytical figures of merit of the thermodenuder are reported for benzo[a]pyrene, benzo[b]fluoranthene, and benzo[ghi]-perylene on ultrafine soot and NaCl aerosols. By thermodesorption of the PAH, problems due to quenching of the PAH fluorescence by the bulk aerosol material or excimer formation on the aerosol surface were avoided. For the PAH under study, the sensitivity was improved considerably and detection limits between 110 and 850 ng m(-3) were attained, while a response time of 2-3 min was achieved with the thermodenuder. A calibration for PAH on ultrafine soot and NaCl aerosols was established independent of the aerosol substrate.
Spectroscopic study of fluorescent probes based on G-quadruplex oligonucleotides labeled with ethynylpyrenyldeoxyuridine.

PubMed

Switalska, Angelika; Kierzek, Ryszard; Dembska, Anna; Juskowiak, Bernard

2017-12-01

The design, synthesis, and spectral properties of four pyrene labeled oligonucleotide probes with G-quadruplex structure (Tel22-Tpy, Tel22-Upy, Tel22-6Upy, Tel22-18Upy) based on the 22-mer human telomeric sequence (Tel22) have been reported. Pyrene labels in the form of ethynylpyrenyldeoxyuridine have been inserted efficiently into oligodeoxynucleotides probes using phosphoramidite chemistry. The probes exhibited abilities to fold into G-quadruplex structures and to bind metal cations (Na + and K + ). Folding properties of probes and their spectral behavior were examined by recording the UV-vis, fluorescence, and CD spectra as well as by analyzing melting profiles. Fluorescence characteristics and G-quadruplex folding of probes were also studied at the interface of cationic dioctadecyldimethylammonium bromide (DODAB) monolayer. Investigations included film balance measurements (π-A isotherms) and fluorescence spectra recording using a fiber optic accessory interfaced with a spectrofluorimeter. Copyright © 2017 Elsevier B.V. All rights reserved.
Thermal characterization of poly(ethylene glycol)-poly(D,L-lactide) block copolymer micelles based on pyrene excimer formation.

PubMed

Jule, Eduardo; Yamamoto, Yuji; Thouvenin, Muriel; Nagasaki, Yukio; Kataoka, Kazunori

2004-07-07

Poly(ethylene glycol)--poly(D,L-lactide) (PEG-PDLLA) block copolymers were prepared by anionic ring-opening polymerization, resulting in block sizes effectively controlled by initial monomer/initiator ratios and low molecular weight distributions (<1.12). A pyrene derivative (1-pyrenyl carbonyl cyanide--Py) was conjugated to the end of the hydrophobic block (PDLLA) in a quantitative manner, with coupling efficiencies >95%. The so-obtained PEG-PDLLA-Py copolymers displayed fluorescent properties that were associated with the pyrene monomers, when placed in good solvents for both the hydrophilic and hydrophobic blocks. When placed in selective solvents, these copolymers self-assembled into micelles in the 30-nm range, also with low particle size distributions (<0.09), within which Py could be readily entrapped in the hydrophobic PDLLA core. Py entrapment resulted in the formation of excimers, as evident from fluorescence measurements. Observation of excimer formation/dissociation further conveyed information on the physicochemical properties of the core. Thermal characterization of these systems showed that an increase in the temperature resulted in changes in the properties of excimer fluorescence, an occurrence attributed to a higher mobility of the otherwise glassy PDLLA. This, in turn, greatly affected the inter-molecular distance between pyrene molecules, a crucial factor for excimer formation. The glass transition of the PDLLA block, approximately 38 degrees C, defined the onset for increasing chain mobility and whence excimer dissociation. Excimer fluorescence appeared to be time-dependent. Based on these observations, chain exchange processes were clearly evidenced through the time-dependent dissociation of excimers into unimers, a process that was influenced by changes in temperature.
Electrochemical synthesis, characterization and electrochromic properties of a copolymer based on 1,4-bis(2-thienyl)naphthalene and pyrene

NASA Astrophysics Data System (ADS)

Wang, Bin; Zhao, Jinsheng; Cui, Chuansheng; Wang, Min; Wang, Zhong; He, Qingpeng

2012-05-01

Electrochemical copolymerization of 1,4-bis(2-thienyl)naphthalene (BTN) with pyrene is carried out in acetonitrile (ACN) solution containing sodium perchlorate (NaClO4) as a supporting electrolyte. Characterizations of the resulting copolymer P(BTN-co-pyrene) are performed by cyclic voltammetry (CV), UV-vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The P(BTN-co-pyrene) film has distinct electrochromic properties and exhibits three different colors (yellowish green, green and blue) under various potentials. Maximum contrast (ΔT%) and response time of the copolymer film are measured as 37.8% and 1.71 s at 687 nm. An electrochromic device (ECD) based on P(BTN-co-pyrene) and poly(3,4-ethylenedioxythiophene) (PEDOT) is constructed and characterized. Neutral state of device shows green color while oxidized state reveals blue color. This ECD shows a maximum optical contrast (ΔT%) of 24.4% with a response time of 0.43 s at 635 nm. The coloration efficiency (CE) of the device is calculated to be 349 cm2 C-1 at 635 nm. In addition, the ECD also has satisfactory optical memories and redox stability.
Determination of high-molecular weight polycyclic aromatic hydrocarbons in high performance liquid chromatography fractions of coal tar standard reference material 1597a via solid-phase nanoextraction and laser-excited time-resolved Shpol'skii spectroscopy

PubMed Central

Wilson, Walter B.; Alfarhani, Bassam; Moore, Anthony F. T.; Bisson, Cristina; Wise, Stephen A.; Campiglia, Andres D.

2016-01-01

This article presents an alternative approach for the analysis of high molecular weight – polycyclic aromatic hydrocarbons (HMW-PAHs) with molecular mass 302 Da in complex environmental samples. This is not a trivial task due to the large number of molecular mass 302 Da isomers with very similar chromatographic elution times and similar, possibly even virtually identical, mass fragmentation patterns. The method presented here is based on 4.2 K laser-excited time-resolved Shpol'skii spectroscopy, a high resolution spectroscopic technique with the appropriate selectivity for the unambiguous determination of PAHs with the same molecular mass. The potential of this approach is demonstrated here with the analysis of a coal tar standard reference material (SRM) 1597a. Liquid chromatography fractions were submitted to the spectroscopic analysis of five targeted isomers, namely dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene, naphtho[2,3-a]pyrene and dibenzo[a,h]pyrene. Prior to analyte determination, the liquid chromatographic fractions were pre-concentrated with gold nanoparticles. Complete analysis was possible with microliters of chromatographic fractions and organic solvents. The limits of detection varied from 0.05 (dibenzo[a,l]pyrene) to 0.24 μg L−1 (dibenzo[a,e]pyrene). The excellent analytical figures of merit associated to its non-destructive nature, which provides ample opportunity for further analysis with other instrumental methods, makes this approach an attractive alternative for the determination of PAH isomers in complex environmental samples. PMID:26653471
Fluorescence Studies of Lysozyme Nucleation

NASA Technical Reports Server (NTRS)

Pusey, Marc L.; Smith, Lori

1998-01-01

Fluorescence is one of the most powerful tools available for the study of macromolecules. For example, fluorescence can be used to study self association through methods such as anisotropy (the rotational rate of the molecule in solution), quenching (the accessibility of a bound probe to the bulk solution), and resonance energy transfer (measurement of the distance between two species). Fluorescence can also be used to study the local environment of the probe molecules, and the changes in that environment which accompany crystal nucleation and growth. However fluorescent techniques have been very much underutilized in macromolecular growth studies. One major advantage is that the fluorescent species generally must be at low concentration, typically ca 10-5 to 10-6 M. Thus one can study a very wide range of solution conditions, ranging from very high to very low protein concentration, he latter of which are not readily accessible to scattering techniques. We have prepared a number of fluorescent derivatives of chicken egg white lysozyme (CEWL). Fluorescent probes have been attached to two different sites, ASP 101 and the N-terrninal amine, with a sought for use in different lines of study. Preliminary resonance energy transfer studies have been -carried out using pyrene acetic acid (Ex 340 mn, Em 376 nm) lysozyme as a donor and cascade blue (Ex 377 run, Em 423 nm) labeled lysozyme as an acceptor. The emission of both the pyrene and cascade blue probes was followed as a function of the salt protein concentrations. The data show an increase in cascade blue and a concomitant decrease in the pyrene fluorescence as either the salt or protein concentrations are increased, suggesting that the two species are approaching each other close enough for resonance energy transfer to occur. This data can be analyzed to measure the distance between the probe molecules and, knowing their locations on the protein molecule their distances from and orientations with respect to each other. The results of these and other studies will be discussed.
A pyrene-based fluorescent sensor for Zn2+ ions: a molecular 'butterfly'.

PubMed

Manandhar, Erendra; Broome, J Hugh; Myrick, Jalin; Lagrone, Whitney; Cragg, Peter J; Wallace, Karl J

2011-08-21

A simple pyrene-based triazole receptor has been synthesised and shown to self-assemble in the presence of ZnCl(2) in an exclusively 2:1 ratio, whereas a mixture of 2:1 and 1:1 ratios are observed for other Zn(2+) salts. The pyrene units are syn in orientation; this is supported by a strong excimer signal observed at 410 nm in the presence of ZnCl(2) in acetonitrile. DFT calculations and 2D NMR support the proposed structure. This journal is © The Royal Society of Chemistry 2011
Pyrene-based dyad and triad leading to a reversible chemical and redox optical and magnetic switch.

PubMed

Franco, Carlos; Mas-Torrent, Marta; Caballero, Antonio; Espinosa, Arturo; Molina, Pedro; Veciana, Jaume; Rovira, Concepció

2015-03-27

Two new pyrene-polychlorotriphenylmethyl (PTM) dyads and triads have been synthesized and characterized by optical, magnetic, and electrochemical methods. The interplay between the different electronic states of the PTM moiety in the dyads and triads and the optical and magnetic properties of the molecules have been studied. The electronic spectra of the radicals 5(.) and 6(.) show the intramolecular charge-transfer transition at around 700 nm due to the acceptor character of the PTM radical. In the diamagnetic protonated derivatives 3 and 4 the fluorescence due to the pyrene is maintained, whereas in the radicals 5(.) and 6(.) and the corresponding anions 5(-) and 6(-) there is a clear quenching of the fluorescence, which is more efficient in the case of radicals. The redox activity of PTM radicals that are easily reduced to the corresponding carbanion has been exploited to fabricate electrochemical switches with optical and magnetic response. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Effect of humic acid on pyrene removal from water by polycation-clay mineral composites and activated carbon.

PubMed

Radian, Adi; Mishael, Yael

2012-06-05

Pyrene removal by polycation-montmorillonite (MMT) composites and granulated activated carbon (GAC) in the presence of humic acid (HA) was examined. Pyrene, HA, and sorbent interactions were characterized by FTIR, fluorescence and zeta measurements, adsorption, and column filtration experiments. Pyrene binding coefficients to the macromolecules were in the order of PVPcoS (poly-4-vinylpiridine-co-styrene) > HA > PDADMAC (poly diallyl-dimethyl-ammonium-chloride), correlating to pyrene-macromolecules compatibility. Electrostatic interactions explained the high adsorption of HA to both composites (∼100%), whereas HA adsorption by GAC was low. Pyrene removal by the composites, unlike GAC, was enhanced in the presence of HA; removal by PDADMAC-MMT increased from ∼50 (k(d) = 2.2 × 10(3) kg/L) to ∼70% (k(d) = 2.4 × 10(3) kg/L) in the presence of HA. This improvement was attributed to the adsorption of pyrene-HA complexes. PVPcoS-MMT was most efficient in removing pyrene (k(d) = 1.1 × 10(4) kg/L, >95% removal) which was explained in terms of specific π donor-π acceptor interactions. Pyrene uptake by column filters of GAC reached ∼50% and decreased to ∼30% in the presence of HA. Pyrene removal by the PVPcoS-MMT filter was significantly higher (100-85% removal), exhibiting only a small decrease in the presence of HA. The utilization of HA as an enhancing agent in pollutant removal is novel and of major importance in water treatment.
Cellular imaging using BODIPY-, pyrene- and phthalocyanine-based conjugates.

PubMed

Bizet, Faustine; Ipuy, Martin; Bernhard, Yann; Lioret, Vivian; Winckler, Pascale; Goze, Christine; Perrier-Cornet, Jean-Marie; Decréau, Richard A

2018-01-15

Fluorescent Probes aimed at absorbing in the blue/green region of the spectrum and emitting in the green/red have been synthesized (as the form of dyads-pentads), studied by spectrofluorimetry, and used for cellular imaging. The synthesis of phthalocyanine-pyrene 1 was achieved by cyclotetramerization of pyrenyldicyanobenzene, whereas phthalocyanine-BODIPY 2c was synthesized by Sonogashira coupling between tetraiodophthalocyanine and meso-alkynylBODIPY. The standard four-steps BODIPY synthesis was applied to the BODIPY-pyrene dyad 3 starting from pyrenecarbaldehyde and dimethylpyrrole. 1 H, 13 C, 19 F, 11 BNMR, ICP, MS, and UV/Vis spectroscopic analyses demonstrated that 2c is a mixture of BODIPY-Pc conjugates corresponding to an average ratio of 2.5 BODIPY per Pc unit, where its bis, tris, tetrakis components could not be separated. Fluorescence emission studies (μM concentration in THF) showed that the design of the probes allowed excitation of their antenna (pyrene, BODIPY) in the blue/green region of the spectrum, and subsequent transfer to the acceptor platform (BODIPY, phthalocyanine) followed by its emission in the green/red (with up to 140-350 nm overall Stokes shifts). The fluorescent probes were used for cellular imaging of B16F10 melanoma cells upon solubilization in 1% DMSO containing RPMI or upon encapsulation in liposomes (injection method). Probes were used at 1-10 μM concentrations, cells were fixed with methanol and imaged by biphoton and/or confocal microscopy, showing that probes could achieve the staining of cells membranes and not the nucleus. Copyright © 2017. Published by Elsevier Ltd.
Photochemistry of pyrene with water at low temperature: study of atmospherical and astrochemical interest.

PubMed

Guennoun, Zohra; Aupetit, Christian; Mascetti, Joëlle

2011-03-17

Photochemistry of a polyaromatic hydrocarbon, pyrene C(16)H(10), with water has been investigated at cryogenic temperatures. Photoprocessing of this species, performed at λ > 235 nm, in argon matrices, adsorbed onto amorphous water surfaces, and trapped in solid water, led to the formation of ketonic isomers, C(16)H(10)O, and possibly quinones. These species have been identified for the first time by infrared spectroscopy with the support of isotopic substitution experiments and DFT calculations. These oxidized pyrene-like species, of atmospherical and astrochemical interest, most likely arise from a tautomeric rearrangement of their analogous hydroxylated molecules, these latter being formed by reaction of water with pyrene cations.
Pyrene maleimide as a probe of microenvironmental and dynamics properties of protein binding sites

NASA Astrophysics Data System (ADS)

Benci, S.; Vaccari, S.; Schianchi, G.; Locatelli, Donata; Vaghi, P.; Bottiroli, Giovanni F.

1995-01-01

N-(1-Pyrene)maleimide is highly fluorescent upon covalent binding with sulfhydryl and amino groups of the proteins. Multiexponential fluorescence decays were observed for the dye bound to different proteins even when a single binding site is involved. The lack of information about the fluorescence decay of free dye does not allow to define the variations of fluorescence parameter following the conjugation and their correlation with the binding properties of the fluorophore. In this work, a study of the fluorescence of the probe, free in solution, bound to different antibodies and to the antigen-antibody complex both in solution and in cell, has been performed. The experimental results showed that chemico-physical properties of the medium influence the fluorescence decay of the probe in both the free and bound forms, although to a different extent. The variations of fluorescence decay and anisotropy of the bound probe are related to the electronic characteristics of microenvironment and show an increased stabilization of the probe binding site with the increasing complexity of the substrate. The sensitivity of the fluorescence properties of the probe to the binding site environment opens interesting perspectives concerning the application of Py- maleimide fluorochromization to assess the degree of specificity of immunocytochemical labelling.
Nine New Fluorescent Probes

NASA Astrophysics Data System (ADS)

Lin, Tsung-I.; Jovanovic, Misa V.; Dowben, Robert M.

1989-06-01

Absorption and fluorescence spectroscopic studies are reported here for nine new fluorescent probes recently synthesized in our laboratories: four pyrene derivatives with substituents of (i) 1,3-diacetoxy-6,8-dichlorosulfonyl, (ii) 1,3-dihydroxy-6,8-disodiumsulfonate, (iii) 1,3-disodiumsulfonate, and (iv) l-ethoxy-3,6,8-trisodiumsulfonate groups, and five [7-julolidino] coumarin derivatives with substituents of (v) 3-carboxylate-4-methyl, (vi) 3- methylcarboxylate, (vii) 3-acetate-4-methyl, (viii) 3-propionate-4-methyl, and (ix) 3-sulfonate-4-methyl groups. Pyrene compounds i and ii and coumarin compounds v and vi exhibit interesting absorbance and fluorescence properties: their absorption maxima are red shifted compared to the parent compound to the blue-green region, and the band width broadens considerably. All four blue-absorbing dyes fluoresce intensely in the green region, and the two pyrene compounds emit at such long wavelengths without formation of excimers. The fluorescence properties of these compounds are quite environment-sensitive: considerable spectral shifts and fluorescence intensity changes have been observed in the pH range from 3 to 10 and in a wide variety of polar and hydrophobic solvents with vastly different dielectric constants. The high extinction and fluorescence quantum yield of these probes make them ideal fluorescent labeling reagents for proteins, antibodies, nucleic acids, and cellular organelles. The pH and hydrophobicity-dependent fluorescence changes can be utilized as optical pH and/or hydrophobicity indicators for mapping environmental difference in various cellular components in a single cell. Since all nine probes absorb in the UV, but emit at different wavelengths in the visible, these two groups of compounds offer an advantage of utilizing a single monochromatic light source (e.g., a nitrogen laser) to achieve multi-wavelength detection for flow cytometry application. As a first step to explore potential application in cancer cell diagnostics, we have found that at least two of these probes are preferentially taken up by cancerous lymphocytes as compared to normal peripheral blood lymphocytes. The feasiblity of using these probes in diagnosing malignant cells in the body fluid of cancer patients directly on a fluorocytometer is presently being investigated.

Methotrexate-Loaded Four-Arm Star Amphiphilic Block Copolymer Elicits CD8+ T Cell Response against a Highly Aggressive and Metastatic Experimental Lymphoma.

PubMed

Hira, Sumit Kumar; Ramesh, Kalyan; Gupta, Uttam; Mitra, Kheyanath; Misra, Nira; Ray, Biswajit; Manna, Partha Pratim

2015-09-16

We have synthesized a well-defined four-arm star amphiphilic block copolymer [poly(DLLA)-b-poly(NVP)]4 [star-(PDLLA-b-PNVP)4] that consists of D,L-lactide (DLLA) and N-vinylpyrrolidone (NVP) via the combination of ring-opening polymerization (ROP) and xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization. Synthesis of the polymer was verified by 1H NMR spectroscopy and gel permeation chromatography (GPC). The amphiphilic four-arm star block copolymer forms spherical micelles in water as demonstrated by transmission electron microscopy (TEM) and 1H NMR spectroscopy. Pyrene acts as a probe to ascertain the critical micellar concentration (cmc) by using fluorescence spectroscopy. Methotrexate (MTX)-loaded polymeric micelles of star-(PDLLA15-b-PNVP10)4 amphiphilic block copolymer were prepared and characterized by fluorescence and TEM studies. Star-(PDLLA15-b-PNVP10)4 copolymer was found to be significantly effective with respect to inhibition of proliferation and lysis of human and murine lymphoma cells. The amphiphilic block copolymer causes cell death in parental and MTX-resistant Dalton lymphoma (DL) and Raji cells. The formulation does not cause hemolysis in red blood cells and is tolerant to lymphocytes compared to free MTX. Therapy with MTX-loaded star-(PDLLA15-b-PNVP10)4 amphiphilic block copolymer micelles prolongs the life span of animals with neoplasia by reducing the tumor load, preventing metastasis and augmenting CD8+ T cell-mediated adaptive immune responses.
Tunable Crystallinity and Charge Transfer in Two-Dimensional G-Quadruplex Organic Frameworks.

PubMed

Wu, Yi-Lin; Bobbitt, N Scott; Logsdon, Jenna L; Powers-Riggs, Natalia E; Nelson, Jordan N; Liu, Xiaolong; Wang, Timothy C; Snurr, Randall Q; Hupp, Joseph T; Farha, Omar K; Hersam, Mark C; Wasielewski, Michael R

2018-04-03

DNA G-quadruplex structures were recently discovered to provide reliable scaffolding for two-dimensional organic frameworks due to the strong hydrogen-bonding ability of guanine. Herein, 2,7-diaryl pyrene building blocks with high HOMO energies and large optical gaps are incorporated into G-quadruplex organic frameworks. The adjustable substitution on the aryl groups provides an opportunity to elucidate the framework formation mechanism; molecular non-planarity is found to be beneficial for restricting interlayer slippage, and the framework crystallinity is highest when intermolecular interaction and non-planarity strike a fine balance. When guanine-functionalized pyrenes are co-crystallized with naphthalene diimide, charge-transfer (CT) complexes are obtained. The photophysical properties of the pyrene-only and CT frameworks are characterized by UV/Vis and steady-state and time-resolved photoluminescence spectroscopies, and by EPR spectroscopy for the CT complex frameworks. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Lighting Up the Thioflavin T by Parallel-Stranded TG(GA) n DNA Homoduplexes.

PubMed

Zhu, Jinbo; Yan, Zhiqiang; Zhou, Weijun; Liu, Chuanbo; Wang, Jin; Wang, Erkang

2018-06-22

Thioflavin T (ThT) was once regarded to be a specific fluorescent probe for the human telomeric G-quadruplex, but more other kinds of DNA were found that can also bind to ThT in recent years. Herein, we focus on G-rich parallel-stranded DNA and utilize fluorescence, absorbance, circular dichroism, and surface plasmon resonance spectroscopy to investigate its interaction with ThT. Pyrene label and molecular modeling are applied to unveil the binding mechanism. We find a new class of non-G-quadruplex G-rich parallel-stranded ( ps) DNA with the sequence of TG(GA) n can bind to ThT and increase the fluorescence with an enhancement ability superior to G-quadruplex. The optimal binding specificity for ThT is conferred by two parts. The first part is composed of two bases TG at the 5' end, which is a critical domain and plays an important role in the formation of the binding site for ThT. The second part is the rest alternative d(GA) bases, which forms the ps homoduplex and cooperates with the TG bases at the 5' end to bind the ThT.
A Low-Molecular-Weight Gelator Composed of Pyrene and Fluorene Moieties for Effective Charge Transfer in Supramolecular Ambidextrous Gel.

PubMed

Reddy, Samala Murali Mohan; Dorishetty, Pramod; Augustine, George; Deshpande, Abhijit P; Ayyadurai, Niraikulam; Shanmugam, Ganesh

2017-11-28

Charge-transfer (CT) gel materials obtained from low-molecular-weight (LMW) compounds through a supramolecular self-assembly approach have received fascinating attention by many researchers because of their interesting material property and potential applications. However, most of the CT gel materials constructed were of organogels while the construction of CT gels in the form of a hydrogel is a challenge because of the solubility issue in water, which considerably limits the use of CT hydrogels. Herein, for the first time, we report a new LMW gelator [N α -(fluorenylmethoxycarbonyl)-N ε -(δ-butyric-1-pyrenyl)-l-lysine, (FmKPy)], composed of two functional moieties such as fluorenylmethoxycarbonyl and pyrene, which not only parade both hydro and organo (ambidextrous) supramolecular gel formation but also exhibit CT ambidextrous gels when mixed with an electron acceptor such as 2,4,7-trinitro-9-fluorenone (TNF). This finding is significant as the established CT organogelator in the literature did not form an organogel in the absence of an electron acceptor or lose their gelation property upon the addition of the acceptor. CT between pyrene and TNF was confirmed by the color change as well as the appearance of the CT band in the visible region of the absorption spectrum. CT between FmKPy and TNF was supported by the solvent dilution method using tetrahydrofuran as the gel breaker and pyrene fluorescence quenching in the case compound containing pyrene and TNF. The morphology of FmKPy ambidextrous gels indicates the fibrous nature while the self-assembled structure is primarily stabilized by π-π stacking among fluorenyl and pyrenyl moieties and hydrogen bonding between amide groups. The FmKPy-TNF CT ambidextrous gel retains the fibrous nature; however, the size of the fibers changed. In FmKPy-TNF CT gels, TNF is intercalated between pyrene moieties in the self-assembled structure as confirmed by fluorescence quenching and powder X-ray diffraction. The FmKPy ambidextrous gel exhibits significant properties such as low minimum gelation concentration (MGC), thixotropic nature, pH stimuli response, and high thermal stability. Upon the addition of TNF, the FmKPy-TNF CT ambidextrous gel maintains all these properties except MGC which increased for FmKPy-TNF. Because pyrene-based LMW organogels have been developed widely for many applications while their hydrogels were limited, the current finding of the pyrene-based ambidextrous fluorescent gel with the CT property provides a wide opportunity to use FmKPy as a soft material maker and also for potential applications in fields like surface coating, three-dimensional printing, and so forth.
A fluorescent probe for ecstasy.

PubMed

Masseroni, D; Biavardi, E; Genovese, D; Rampazzo, E; Prodi, L; Dalcanale, E

2015-08-18

A nanostructure formed by the insertion in silica nanoparticles of a pyrene-derivatized cavitand, which is able to specifically recognize ecstasy in water, is presented. The absence of effects from interferents and an efficient electron transfer process occurring after complexation of ecstasy, makes this system an efficient fluorescent probe for this popular drug.
Ultrafast third-order nonlinear optical response of pyrene derivatives

NASA Astrophysics Data System (ADS)

Shi, Yufang; Li, Zhongguo; Fang, Yu; Sun, Jinyu; Zhao, Minggen; Song, Yinglin

2017-05-01

Two mono-substituted pyrene derivatives with delocalized electron system 1-(pyren-1-yl)-3-(4-Methyl thiophene-2-yl) acrylic ketone (13#) and 1-(pyren-1-yl)-3-(4-bromo thiophene-2-yl) acrylic ketone (15#) were successfully synthesized. The resultant compounds were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (IR), high resolution mass spectrum (HR-MS), and UV-vis spectra. The third-order nonlinear optical properties of the compounds were investigated using Z-scan technique with femtosecond laser pulses at 500 nm and 700 nm, respectively. Both of the compounds showed a decrease in transmittance about the focus, which are typical of two-photon absorption. It was found that the two-photon absorption behavior of the pyrene derivatives were modified by substituents on thiophene ring. These results indicate that both compounds can be promising candidates for future optoelectronic and bio-imaging applications.
Extremely fast and highly selective detection of nitroaromatic explosive vapours using fluorescent polymer thin films.

PubMed

Demirel, Gokcen Birlik; Daglar, Bihter; Bayindir, Mehmet

2013-07-14

A novel sensing material based on pyrene doped polyethersulfone worm-like structured thin film is developed using a facile technique for detection of nitroaromatic explosive vapours. The formation of π-π stacking in the thin fluorescent film allows a highly sensitive fluorescence quenching which is detectable by the naked eye in a response time of a few seconds.
A portable explosive detector based on fluorescence quenching of pyrene deposited on coloured wax-printed μPADs.

PubMed

Taudte, Regina Verena; Beavis, Alison; Wilson-Wilde, Linzi; Roux, Claude; Doble, Philip; Blanes, Lucas

2013-11-07

A new technique for the detection of explosives has been developed based on fluorescence quenching of pyrene on paper-based analytical devices (μPADs). Wax barriers were generated (150 °C, 5 min) using ten different colours. Magenta was found as the most suitable wax colour for the generation of the hydrophobic barriers with a nominal width of 120 μm resulting in fully functioning hydrophobic barriers. One microliter of 0.5 mg mL(-1) pyrene dissolved in an 80:20 methanol-water solution was deposited on the hydrophobic circle (5 mm diameter) to produce the active microchip device. Under ultra-violet (UV) illumination, ten different organic explosives were detected using the μPAD, with limits of detection ranging from 100-600 ppm. A prototype of a portable battery operated instrument using a 3 W power UV light-emitting-diode (LED) (365 nm) and a photodiode sensor was also built and evaluated for the successful automatic detection of explosives and potential application for field-based screening.
Isomer discrimination of PAHs formed in sooting flames by jet-cooled laser-induced fluorescence: application to the measurement of pyrene and fluoranthene

NASA Astrophysics Data System (ADS)

Mouton, Thomas; Mercier, Xavier; Desgroux, Pascale

2016-05-01

Jet-cooled laser-induced fluorescence is a spectroscopic method, specifically developed for the study of PAHs formed in flames. This technique has already been used to measure different aromatic species in sooting low-pressure methane flames such as benzene, naphthalene, and pyrene. The use of the LIF technique to excite PAHs drastically cooled down inside a supersonic jet offers the possibility to get selective and quantitative profiles of PAHs sampled from sooting flames. In this paper, we demonstrate the ability of this experimental method to separate the contribution of two mass isomers generated in sooting flames which are the pyrene and the fluoranthene. The selectivity of the method is demonstrated by studying the spectral properties of these species. The method is then applied to the measurement of both these species in two sooting flames with different equivalence ratios and stabilized at 200 torr (26.65 kPa). The sensitivity of the technique has been found to reach a few ppb in the case of fluoranthene measurements.
Pyrene-based chemosens or detects picric acid upto attogram level through aggregation enhanced excimer emission.

PubMed

Chopra, Rakesh; Kaur, Paramjit; Singh, Kamaljit

2015-03-15

A pyrene-based small molecular weight probe, exhibiting aggregation enhanced excimer emission has been synthesized. The crystalline emissive form detects 2,4,6-trinitrophenol (picric acid) at parts-per-billion concentration in solution and as low as 0.46 attogram in direct contact mode, operating predominantly in a static quenching mechanism, proposed on the basis of steady state and life-time fluorescence measurements. Copyright © 2015 Elsevier B.V. All rights reserved.
Pyrene-nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies.

PubMed

Jabłoński, Artur; Fritz, Yannic; Wagenknecht, Hans-Achim; Czerwieniec, Rafał; Bernaś, Tytus; Trzybiński, Damian; Woźniak, Krzysztof; Kowalski, Konrad

2017-01-01

Fluorescent pyrene-linker-nucleobase (nucleobase = thymine, adenine) conjugates with carbonyl and hydroxy functionalities in the linker were synthesized and characterized. X-ray single-crystal structure analysis performed for the pyrene-C(O)CH 2 CH 2 -thymine ( 2 ) conjugate reveals dimers of molecules 2 stabilized by hydrogen bonds between the thymine moieties. The photochemical characterization showed structure-dependent fluorescence properties of the investigated compounds. The conjugates bearing a carbonyl function represent weak emitters as compared to compounds with a hydroxy function in the linker. The self-assembly properties of pyrene nucleobases were investigated in respect to their binding to single and double strand oligonucleotides in water and in buffer solution. In respect to the complementary oligothymidine T 10 template in water, compounds 3 and 5 both show a self-assembling behavior according to canonical base-base pairing. However, in buffer solution, derivative 5 was much more effective than 3 in binding to the T 10 template. Furthermore the adenine derivative 5 binds to the double-stranded (dA) 10 -T 10 template with a self-assembly ratio of 112%. Such a high value of a self-assembly ratio can be rationalized by a triple-helix-like binding, intercalation, or a mixture of both. Remarkably, compound 5 also shows dual staining pattern in living HeLa cells. Confocal microscopy confirmed that 5 predominantly stains mitochondria but it also accumulates in the nucleoli of the cells.
A fluorescent paramagnetic Mn metal–organic framework based on semi-rigid pyrene tetracarboxylic acid: sensing of solvent polarity and explosive nitroaromatics

PubMed Central

Bajpai, Alankriti; Mukhopadhyay, Arindam; Krishna, Manchugondanahalli Shivakumar; Govardhan, Savitha; Moorthy, Jarugu Narasimha

2015-01-01

An Mn metal–organic framework (Mn-MOF), Mn-L, based on a pyrene-tetraacid linker (H4 L), displays a respectable fluorescence quantum yield of 8.3% in spite of the presence of the paramagnetic metal ions, due presumably to fixation of the metal ions in geometries that do not allow complete energy/charge-transfer quenching. Remarkably, the porous Mn-L MOF with ∼25% solvent-accessible volume exhibits a heretofore unprecedented solvent-dependent fluorescence emission maximum, permitting its use as a probe of solvent polarity; the emission maxima in different solvents correlate excellently with Reichardt’s solvent polarity parameter (E T N). Further, the applicability of Mn-L to the sensing of nitroaromatics via fluorescence quenching is demonstrated; the detection limit for TNT is shown to be 125 p.p.m. The results bring out the fact that MOFs based on paramagnetic metal ions can indeed find application when the quenching mechanisms are attenuated by certain geometries of the organic linkers of the MOF. PMID:26306197
A fluorescent paramagnetic Mn metal-organic framework based on semi-rigid pyrene tetra-carboxylic acid: sensing of solvent polarity and explosive nitroaromatics.

PubMed

Bajpai, Alankriti; Mukhopadhyay, Arindam; Krishna, Manchugondanahalli Shivakumar; Govardhan, Savitha; Moorthy, Jarugu Narasimha

2015-09-01

An Mn metal-organic framework (Mn-MOF), Mn-L, based on a pyrene-tetraacid linker (H4 L), displays a respectable fluorescence quantum yield of 8.3% in spite of the presence of the paramagnetic metal ions, due presumably to fixation of the metal ions in geometries that do not allow complete energy/charge-transfer quenching. Remarkably, the porous Mn-L MOF with ∼25% solvent-accessible volume exhibits a heretofore unprecedented solvent-dependent fluorescence emission maximum, permitting its use as a probe of solvent polarity; the emission maxima in different solvents correlate excellently with Reichardt's solvent polarity parameter (E T (N)). Further, the applicability of Mn-L to the sensing of nitroaromatics via fluorescence quenching is demonstrated; the detection limit for TNT is shown to be 125 p.p.m. The results bring out the fact that MOFs based on paramagnetic metal ions can indeed find application when the quenching mechanisms are attenuated by certain geometries of the organic linkers of the MOF.
Ultrasound Induced Fluorescence of Nanoscale Liposome Contrast Agents

PubMed Central

Zhang, Qimei; Morgan, Stephen P.; O’Shea, Paul; Mather, Melissa L.

2016-01-01

A new imaging contrast agent is reported that provides an increased fluorescent signal upon application of ultrasound (US). Liposomes containing lipids labelled with pyrene were optically excited and the excimer fluorescence emission intensity was detected in the absence and presence of an ultrasound field using an acousto-fluorescence setup. The acousto-fluorescence dynamics of liposomes containing lipids with pyrene labelled on the fatty acid tail group (PyPC) and the head group (PyPE) were compared. An increase in excimer emission intensity following exposure to US was observed for both cases studied. The increased intensity and time constants were found to be different for the PyPC and PyPE systems, and dependent on the applied US pressure and exposure time. The greatest change in fluorescence intensity (130%) and smallest rise time constant (0.33 s) are achieved through the use of PyPC labelled liposomes. The mechanism underlying the observed increase of the excimer emission intensity in PyPC labelled liposomes is proposed to arise from the “wagging” of acyl chains which involves fast response and requires lower US pressure. This is accompanied by increased lipid lateral diffusivity at higher ultrasound pressures, a mechanism that is also active in the PyPE labelled liposomes. PMID:27467748
Line narrowing spectroscopic studies of DNA-carcinogen adducts and DNA-dye complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suh, Myungkoo

1995-12-06

Laser-induced fluorescence line narrowing and non-line narrowing spectroscopic methods were applied to conformational studies of stable DNA adducts of the 7β, 8α-dihydoxy-9α, l0α-epoxy-7,8,9, 10-tetrahydrobenzo[α]pyrene (anti-BPDE). Stereochemically distinct (+)-trans-, (-)-trans-, (+)-cis- and (-)-cis adducts of anti-BPDE bound to exocyclic amino group of the central guanine in an 11-mer oligonucleotide, exist in a mixture of conformations in frozen aqueous buffer matrices. The (+)-trans adduct adopts primarily an external conformation with a smaller fraction ( ~25 %) exists in a partially base-stacked conformation. Both cis adducts were found to be intercalated with significant π-π stacking interactions between the pyrenyl residues and the bases.more » Conformations of the trans-adduct of (+)-anti -BPDE in 11-mer oligonucleotides were studied as a function of flanking bases. In single stranded form the adduct at G 2 or G 3 (5 ft-flanking, base guanine) adopts a conformation with strong, interaction with the bases. In contrast, the adduct with a 5ft-flanking, thymine exists in a primarily helixexternal conformation. Similar differences were observed in the double stranded oligonucleotides. The nature of the 3ft-flanking base has little influence on the conformational equilibrium of the (+)-trans-anti BPDE-dG adduct. The formation and repair of BPDE-N 2-dG in DNA isolated from the skin of mice treated topically with benzo[α]pyrene (BP) was studied. Low-temperature fluorescence spectroscopy of the intact DNA identified the major adduct as (+)-trans-anti-BPDE-N-dG, and the minor adduct fraction consisted mainly of (+)-cis-anti-BPDE-N 2-dG.« less
Solution Properties of Dissymmetric Sulfonate-type Anionic Gemini Surfactants.

PubMed

Yoshimura, Tomokazu; Akiba, Kazuki

2016-01-01

Dissymmetric and symmetric anionic gemini surfactants, N-alkyl-N'-alkyl-N,N'dipropanesulfonylethylenediamine (CmCnSul, where m and n represent alkyl chain lengths of m-n = 4-16, 6-14, 8-12, 10-10, and 12-12), were synthesized by two- or three-step reactions. Their physicochemical properties were characterized by equilibrium surface tension measurements, steady-state fluorescence spectroscopy of pyrene, and dynamic light scattering. The critical micelle concentration (CMC) of the dissymmetric surfactants C4C16Sul, C6C14Sul, and C8C12Sul was slightly lower than that of the symmetric surfactant C10C10Sul. The occupied area per molecule (A) of C8C12Sul was smaller than that of C10C10Sul, indicating that C8C12Sul has a high surface activity. However, the increase in the degree of dissymmetry from C8C12Sul to C6C14Sul and then to C4C16Sul resulted in high surface tension and large A. Based on the surface tension, the standard free energies of micellization (∆G°mic) and adsorption (∆G°ads), the efficiency of surface adsorption (pC20), and the effectiveness of surface adsorption (CMC/C20) were obtained. These parameters suggested that C8C12Sul formed micelles more readily than the other surfactants. The properties determined from the surface tension indicated that C8C12Sul's ability is intermediate between those of C10C10Sul and C12C12Sul. The pyrene fluorescence and dynamic light scattering results revealed that the micelle size depends on the longer of the two alkyl chains in dissymmetric surfactants.
A fluorescence study of liposomes entrapped in sol-gel materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamanaka, S.A.; Singh, S.; Sasaki, D.Y.

1997-12-31

Liposomes of phosphatidylcholine lipids were successfully entrapped in silicates using the sol-gel method with complete retention of the molecular aggregates over long periods in aqueous solution. Fluorescent studies of the small unilamellar vesicles of 5% pyrene labeled lipid PSIDA with DSPC remobilized in the gel found significant lipid reorganization upon aging in aqueous solutions. Monitoring of pyrene excimer (470 nm) to monomer (375 nm) ratios in the bilayer reveals that the silicate matrix tends to disperse PSIDA lipid aggregates from that observed in free solution. On an interesting note, the liposomes in the gel at pH 7.5. The PSIDA/DSPC liposomes,more » sensitive to heavy metal ions in free solution, maintain similar sensitivity in the gel yet the sensor material can not be recycled.« less
Temperature-dependent vibrational spectroscopy to study order-disorder transitions in charge transfer complexes

NASA Astrophysics Data System (ADS)

Isaac, Rohan; Goetz, Katelyn P.; Roberts, Drew; Jurchescu, Oana D.; McNeil, L. E.

2018-02-01

Charge-transfer (CT) complexes are a promising class of materials for the semiconductor industry because of their versatile properties. This class of compounds shows a variety of phase transitions, which are of interest because of their potential impact on the electronic characteristics. Here temperature-dependent vibrational spectroscopy is used to study structural phase transitions in a set of organic CT complexes. Splitting and broadening of infrared-active phonons in the complex formed between pyrene and pyromellitic dianhydride (PMDA) confirm the structural transition is of the order-disorder type and complement previous x-ray diffraction (XRD) results. We show that this technique is a powerful tool to characterize transitions, and apply it to a range of binary CT complexes composed of polyaromatic hyrdocarbons (anthracene, perylene, phenanthrene, pyrene, and stilbene) and PMDA. We extend the understanding of transitions in perylene-PMDA and pyrene-PMDA, and show that there are no order-disorder transitions present in anthracene-PMDA, stilbene-PMDA and phenanthrene-PMDA in the temperature range investigated here.
Reconsideration of the Detection and Fluorescence Mechanism of a Pyrene-Based Chemosensor for TNT.

PubMed

Lu, Meiheng; Zhou, Panwang; Ma, Yinhua; Tang, Zhe; Yang, Yanqiang; Han, Keli

2018-02-08

The rapid detection of chemical explosives is crucial for national security and public safety, and the investigation of sensing mechanisms is important for designing highly efficient chemosensors. This study theoretically investigates the detection and fluorescence mechanism of a newly synthesized pyrene-based chemosensor for the detection of trinitrotoluene (TNT) through density-functional-theory (DFT) and time-dependent density-functional-theory (TDDFT) methods and suggests a different interaction product of the probe and TNT from previously reported ones [ Mosca et al. J. Am. Chem. Soc. 2015 , 137 , 7967 ]. Instead of forming Meisenheimer complexes, the energies of which are beyond those of the reactants, a low-energy product generated by a π-π-stacking interaction is more rational and favorable. The fluorescence-quenching property further confirms that the π-π-stacking product is the predicted one rather than luminescent Meisenheimer complexes. Frontier-molecular-orbital (FMO)-analysis results show that photoinduced electron transfer (PET) is the mechanism underlying the luminescence quenching of the probe upon exposure to TNT.
Chemical sensing of Benzo[a]pyrene using Corchorus depressus fluorescent flavonoids.

PubMed

Ahmad, Wajiha; Rana, Nosheen Fatima; Riaz, Sundus; Ahmad, Nasir Mehmood; Hameed, Maryam; Naeem, Ayesha; Tahir, Rabbiya

2018-04-01

Plant phytochemicals, such as flavonoids are in use for the development of optical biosensor. Benzo[a]pyrene (B[a]P), is a pervasive environmental and dietary carcinogen. A fluorescent assay is developed using plant isolated flavonoid for the detection of B[a]P. High content saponins are excluded from the flavonoid-containing methanolic extract of Corchorus depressus by implying reduction of silver ions by saponins resulting in formation of silver nanoparticles. Isolated plant flavonoids are used to develop a spectrofluorometric assay for the detection of B[a]P. Decrease in the flavonoid fluorescence intensity by B[a]P is found to be based on both static and dynamic quenching. Specificity of the assay for B[a]P was tested for other carcinogens belonging to different classes of compounds. Flavonoids-mediated sensing can be implied for the development of new generation of nanoparticle-based biosensors that can be more sensitive and less susceptible to external factors, such as temperature and humidity.

Monitoring i-motif transitions through the exciplex emission of a fluorescent probe incorporating two (Py)A units.

PubMed

Lee, Il Joon; Kim, Byeang Hyean

2012-02-18

Pairs of pyrene-modified deoxyadenosine ((Py)A) units induce a stable interstrand i-motif structure, which can be characterized by a change in the fluorescence λ(max), with an exciplex emission that is not observable in its single-strand structure. This journal is © The Royal Society of Chemistry 2012
Experimental determination of photostability and fluorescence-based detection of PAHs on the Martian surface

NASA Astrophysics Data System (ADS)

Dartnell, Lewis R.; Patel, Manish R.; Storrie-Lombardi, Michael C.; Ward, John M.; Muller, Jan-Peter

2012-05-01

Even in the absence of any biosphere on Mars, organic molecules, including polycyclic aromatic hydrocarbons (PAHs), are expected on its surface due to delivery by comets and meteorites of extraterrestrial organics synthesized by astrochemistry, or perhaps in situ synthesis in ancient prebiotic chemistry. Any organic compounds exposed to the unfiltered solar ultraviolet spectrum or oxidizing surface conditions would have been readily destroyed, but discoverable caches of Martian organics may remain shielded in the subsurface or within surface rocks. We have studied the stability of three representative polycyclic aromatic hydrocarbons (PAHs) in a Mars chamber, emulating the ultraviolet spectrum of unfiltered sunlight under temperature and pressure conditions of the Martian surface. Fluorescence spectroscopy is used as a sensitive indicator of remaining PAH concentration for laboratory quantification of molecular degradation rates once exposed on the Martian surface. Fluorescence-based instrumentation has also been proposed as an effective surveying method for prebiotic organics on the Martian surface. We find the representative PAHs, anthracene, pyrene, and perylene, to have persistence half-lives once exposed on the Martian surface of between 25 and 60 h of noontime summer UV irradiation, as measured by fluorescence at their peak excitation wavelength. This equates to between 4 and 9.6 sols when the diurnal cycle of UV light intensity on the Martian surface is taken into account, giving a substantial window of opportunity for detection of organic fluorescence before photodegradation. This study thus supports the use of fluorescence-based instrumentation for surveying recently exposed material (such as from cores or drill tailings) for native Martian organic molecules in rover missions.
Molecular detection and in vitro antioxidant activity of S-allyl-L-cysteine (SAC) extracted from Allium sativum.

PubMed

Sun, Y-E; Wang, W-D

2016-06-30

It is well known that Allium sativum has potential applications to clinical treatment of various cancers due to its remarkable ability in eliminating free radicals and increasing metabolism. An allyl-substituted cysteine derivative - S-allyl-L-cysteine (SAC) was separated and identified from Allium sativum. The extracted SAC was reacted with 1-pyrenemethanol to obtain pyrene-labelled SAC (Py-SAC) to give SAC fluorescence properties. Molecular detection of Py-SAC was conducted by steady-state fluorescence spectroscopy and time-resolved fluorescence method to quantitatively measure concentrations of Py-SAC solutions. The ability of removing 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical using Py-SAC was determined through oxygen radical absorbance capacity (ORAC). Results showed the activity of Py-SAC and Vitamin C (VC) with ORAC as index, the concentrations of Py-SAC and VC were 58.43 mg/L and 5.72 mg/L respectively to scavenge DPPH, and 8.16 mg/L and 1.67 mg/L to scavenge •OH respectively. Compared with VC, the clearance rates of Py-SAC to scavenge DPPH were much higher, Py-SAC could inhibit hydroxyl radical. The ability of removing radical showed a dose-dependent relationship within the scope of the drug concentration.
Pyrene-based bisazolium salts: from luminescence properties to janus-type bis-N-heterocyclic carbenes.

PubMed

Gonell, Sergio; Poyatos, Macarena; Peris, Eduardo

2014-07-28

A series of pyrene-based bisazolium salts have been obtained starting from 4,5,9,10-tetrabromo-2,7-di-tert-butylpyrene. The synthetic procedure to the pyrene-bisazoliums (PBIs) reveals an unexpected behavior, as a consequence of the presence of the alkyl groups (alkyl=Me, Et, n-Pr, and n-Bu) coming from the trisalkoxyformate in the final products, instead of the expected tBu of tAmyl groups from the starting tetra-aminated pyrenes. All bisazoliums show fluorescence properties, with emissions in the range of 370-420 nm, and quantum yields ranging from 0.29 to 0.41. The PBIs were used as bis-NHC precursors in the preparation of a series of dirhodium and diiridium complexes, which have been fully characterized. The electrochemical studies on selected dimetallic complexes reveal that the electronic communication between the metals through the polyaromatic linker is negligible. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Particulate polycyclic aromatic hydrocarbons (PAH) in the atmosphere of Bizerte city, Tunisia.

PubMed

Ben Hassine, S; Hammami, B; Ben Ameur, W; El Megdiche, Y; Barhoumi, B; Driss, M R

2014-09-01

The particle-phase concentrations of polycyclic aromatic hydrocarbons (PAH) were determined in 13 air samples collected in an urban area of Bizerte (Tunisia) during 2009-2010. Atmospheric particulate samples were extracted by ultrasonic bath and analyzed by high-performance liquid chromatography with fluorescence detection. PAH were found in all the analyzed air samples and the most abundant compounds were pyrene, fluoranthene, benzo[g,h,i]perylene, benzo[b]fluoranthene, chrysene and benzo[a]pyrene. ∑14-PAH concentrations ranging from 9.38 to 44.81 ng m(-3) with mean value of 25.39 ng m(-3). PAH diagnostic ratio source analysis revealed gasoline and diesel vehicular emissions as major sources. The mean total benzo[a]pyrene toxicity equivalent calculated for samples was 3.66 ng m(-3) and the mean contribution of the carcinogenic potency of benzo[a]pyrene was determined to be 55.8 %. Concentrations of particulate PAH in Bizerte city atmosphere were approximately eight times greater than sampled at a nearby rural site.
Pincer-CNC mononuclear, dinuclear and heterodinuclear Au(III) and Pt(II) complexes supported by mono- and poly-N-heterocyclic carbenes: synthesis and photophysical properties.

PubMed

Gonell, S; Poyatos, M; Peris, E

2016-04-07

A family of cyclometallated Au(iii) and Pt(ii) complexes containing a CNC-pincer ligand (CNC = 2,6-diphenylpyridine) supported by pyrene-based mono- or bis-NHC ligands have been synthesized and characterized, together with the preparation of a Pt-Au hetero-dimetallic complex based on a Y-shaped tris-NHC ligand. The photophysical properties of all the new species and of two related Ru(ii)-arene complexes were studied and compared. Whereas the pyrene-based complexes only exhibit emission in solution, those containing the Y-shaped tris-NHC ligand are only luminescent when dispersed in poly(methyl methacrylate) (PMMA). In particular, the pyrene-based complexes were found to be emissive in the range of 373-440 nm, with quantum yields ranging from 3.1 to 6.3%, and their emission spectra were found to be almost superimposable, pointing to the fluorescent pyrene-centered nature of the emission. This observation suggests that the emission properties of the pyrene fragment may be combined with some of the numerous applications of NHCs as supporting ligands allowing, for instance, the design of biological luminescent agents.
Energetic costs of pyrene metabolism in isolated hepatocytes of rainbow trout, Oncorhynchus mykiss.

PubMed

Bains, Onkar S; Kennedy, Christopher J

2004-04-28

The respiratory costs of pyrene exposure and biotransformation were examined in isolated hepatocytes of adult rainbow trout, Oncorhynchus mykiss. Baseline oxygen consumption rates measured at an acclimation temperature of 7.5 degrees C and during an acute temperature increase to 15 degrees C were 10.1 +/- 0.1 and 22.6 +/- 0.4 ng O(2)/min/mg cells, respectively. Hepatocytes exposed to pyrene at 1, 5 and 10 microg/ml exhibited concentration-dependent increases in oxygen consumption. Respiration rates of cells exposed to these concentrations at their acclimation temperature were 12.5 +/- 0.1, 14.7 +/- 0.1 and 17.1 +/- 0.2 ng O(2)/min/mg cells, respectively. Exposure of cells to pyrene at 15 degrees C also elevated oxygen consumption to a maximum of 34.4 +/- 0.3 ng O(2)/min/mg cells, however, the relationship with pyrene concentration was biphasic. The major metabolite identified through a series of solvent extractions, acid hydrolysis, and synchronous fluorometric spectroscopy was conjugated 1-hydroxypyrene. At 7.5 degrees C, increased pyrene metabolism correlated with increased hepatocyte respiration rates. At 15 degrees C, however, pyrene metabolism reached a maximum at 5 microg/ml, suggesting saturation of detoxification enzymes, which correlated with maximum respiration rates at this concentration. Measures of respiration by isolated mitochondria indicated that changes in hepatocyte oxygen consumption were not through direct effects of pyrene on mitochondria. This study indicates that significant respiratory costs may be accrued by teleost hepatocytes actively metabolizing and secreting xenobiotic compounds.
Di-epoxides of the three isomeric dicyclopenta-fused pyrenes: ultimate mutagenic active agents.

PubMed

Otero-Lobato, María José; Kaats-Richters, Veronica E M; Havenith, Remco W A; Jenneskens, Leonardus W; Seinen, Willem

2004-11-14

To rationalize the high bacterial mutagenic response recently found for the (di-) cyclopenta-fused pyrene congeners, viz. cyclopenta[cd]-(1), dicyclopenta[cd,mn]-(2), dicyclopenta[cd,fg]-(3) and dicyclopenta[cd,jk]pyrene (4), in the presence of a metabolic activation mixture (S9-mix), their (di-)epoxides at the externally fused unsaturated five-membered rings were previously proposed as the ultimate mutagenic active forms. In this study, cyclopenta[cd]pyrene-3,4-epoxide (5) and the novel dicyclopenta[cd,mn]pyrene-1,2,4,5-di-epoxide (6), dicyclopenta[cd,fg]pyrene-5,6,7,8-di-epoxide (7) and dicyclopenta[cd,jk]pyrene-1,2,6,7-di-epoxide (8) were synthesised from 1 to 4, respectively, and subsequently assayed for bacterial mutagenicity in the standard microsomal/histidine reverse mutation assay (Ames-assay with Salmonella typhimurium strain TA98). The di-epoxides 6-8 are present as a mixture of their cis- and trans-stereo-isomers in a close to 1:1 ratio ((1)H NMR spectroscopy and ab initio IGLO/III//RHF/6-31G** calculations). The direct-acting mutagenic activity and the strong cytotoxicity exerted by 5-8 both in the absence or presence of an exogenous metabolic activation system (+/-S9-mix) demonstrate that the ultimate mutagenic active forms are the proposed (di-)epoxides of 1-4.
Determination of benzo[a]pyrene in cigarette mainstream smoke by using mid-infrared spectroscopy associated with a novel chemometric algorithm.

PubMed

Zhang, Yan; Zou, Hong-Yan; Shi, Pei; Yang, Qin; Tang, Li-Juan; Jiang, Jian-Hui; Wu, Hai-Long; Yu, Ru-Qin

2016-01-01

Determination of benzo[a]pyrene (BaP) in cigarette smoke can be very important for the tobacco quality control and the assessment of its harm to human health. In this study, mid-infrared spectroscopy (MIR) coupled to chemometric algorithm (DPSO-WPT-PLS), which was based on the wavelet packet transform (WPT), discrete particle swarm optimization algorithm (DPSO) and partial least squares regression (PLS), was used to quantify harmful ingredient benzo[a]pyrene in the cigarette mainstream smoke with promising result. Furthermore, the proposed method provided better performance compared to several other chemometric models, i.e., PLS, radial basis function-based PLS (RBF-PLS), PLS with stepwise regression variable selection (Stepwise-PLS) as well as WPT-PLS with informative wavelet coefficients selected by correlation coefficient test (rtest-WPT-PLS). It can be expected that the proposed strategy could become a new effective, rapid quantitative analysis technique in analyzing the harmful ingredient BaP in cigarette mainstream smoke. Copyright © 2015 Elsevier B.V. All rights reserved.
Ratiometric fluorescent receptors for both Zn2+ and H2PO4(-) ions based on a pyrenyl-linked triazole-modified homooxacalix[3]arene: a potential molecular traffic signal with an R-S latch logic circuit.

PubMed

Ni, Xin-long; Zeng, Xi; Redshaw, Carl; Yamato, Takehiko

2011-07-15

A ratiometric fluorescent receptor with a C(3) symmetric structure based on a pyrene-linked triazole-modified homooxacalix[3]arene (L) was synthesized and characterized. This system exhibited an interesting ratiometric detection signal output for targeting cations and anions through switching the excimer emission of pyrene from the "on-off" to the "off-on" type in neutral solution. (1)H NMR titration results suggested that the Zn(2+) center of receptor L·Zn(2+) provided an excellent pathway of organizing anion binding groups for optimal host-guest interactions. It is thus believed that this receptor has potential application in sensing, detection, and recognition of both Zn(2+) and H(2)PO(4)(-) ions with different optical signals. In addition, the fluorescence emission changes by the inputs of Zn(2+) and H(2)PO(4)(-) ions can be viewed as a combinational R-S latch logic circuit at the molecular level.
Investigation of common fluorophores for the detection of nitrated explosives by fluorescence quenching.

PubMed

Meaney, Melissa S; McGuffin, Victoria L

2008-03-03

Previous studies have indicated that nitrated explosives may be detected by fluorescence quenching of pyrene and related compounds. The use of pyrene, however, invokes numerous health and waste disposal hazards. In the present study, ten safer fluorophores are identified for quenching detection of target nitrated compounds. Initially, Stern-Volmer constants are measured for each fluorophore with nitrobenzene and 4-nitrotoluene to determine the sensitivity of the quenching interaction. For quenching constants greater than 50 M(-1), sensitivity and selectivity are investigated further using an extended set of target quenchers. Nitromethane, nitrobenzene, 4-nitrotoluene, and 2,6-dinitrotoluene are chosen to represent nitrated explosives and their degradation products; aniline, benzoic acid, and phenol are chosen to represent potential interfering compounds. Among the fluorophores investigated, purpurin, malachite green, and phenol red demonstrate the greatest sensitivity and selectivity for nitrated compounds. Correlation of the quenching rate constants for these fluorophores to Rehm-Weller theory suggests an electron-transfer quenching mechanism. As a result of the large quenching constants, purpurin, malachite green, and phenol red are the most promising for future detection of nitrated explosives via fluorescence quenching.
Selective Metal-Ion-Mediated Vesicle Adhesion Based on Dynamic Self-Organization of a Pyrene-Appended Glutamic Acid.

PubMed

Xing, Pengyao; Wang, Yajie; Yang, Minmin; Zhang, Yimeng; Wang, Bo; Hao, Aiyou

2016-07-13

Vesicles with dynamic membranes provide an ideal model system for investigating biological membrane activities, whereby vesicle aggregation behaviors including adhesion, fusion, fission, and membrane contraction/extension have attracted much attention. In this work we utilize an aromatic amino acid (pyrene-appended glutamic acid, PGlu) to prepare nanovesicles that aggregate to form vesicle clusters selectively induced by Fe(3+) or Cu(2+), and the vesicles transform into irregular nano-objects when interacting with Al(3+). Vesicle clusters have better stability than pristine vesicles, which hinders the spontaneous morphological transformation from vesicles into lamellar nanosheets with long incubation period. The difference between complexation of Fe(3+) and Al(3+) with vesicles was studied by various techniques. On the basis of metal ion-vesicle interactions, this self-assembled nanovesicle system also behaves as an effective fluorescent sensor for Fe(3+) and Al(3+), which cause fluorescence quenching and enhanced excimer emission, respectively.
Synthesis and characterization of a fluorescent water-soluble paclitaxel prodrug.

PubMed

Sohn, Jeong-Sun; Choi, Eun-Sun; Jo, Byung-Wook; Hess, Michael; Han, Song-Hee

2010-05-01

A fluorescence susceptible water-soluble paclitaxel was synthesized by a condensation reaction between PEGylated paclitaxel (namely, PP7) and 1-pyrene butyric acid (PBA) in order to obtain a better understanding of the mechanism of action of paclitaxel as well as of the environment of the paclitaxel-binding site. The reaction was performed successfully and the resulting paclitaxel was characterized by FT-NMR, analytical-HPLC, UV spectro photometry, and fluorescence spectrometry. The synthesized paclitaxel analogue showed a high susceptibility to fluorescence in both excitation and emission spectra. And we have investigated the time-resolved fluorescence behavior of them in different solvents and at different excitation wavelengths.
Infrared spectroscopy of matrix-isolated polycyclic aromatic hydrocarbon cations. 2. The members of the thermodynamically most favorable series through coronene

NASA Technical Reports Server (NTRS)

Hudgins, D. M.; Allamandola, L. J.

1995-01-01

Gaseous, ionized polycyclic aromatic hydrocarbons (PAHs) are thought to be responsible for a very common family of interstellar infrared emission bands. Here the near- and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to coronene:phenanthrene, pyrene, benzo[e]pyrene, benzo[ghi]perylene, and coronene, are presented to test this hypothesis. For those molecules that have been studied previously (pyrene, pyrene-d10, and coronene), band positions and relative intensities are in agreement. In all of these cases we report additional features. Absolute integrated absorbance values are given for the phenanthrene, perdeuteriophenanthrene, pyrene, benzo[ghi]perylene, and coronene cations. With the exception of coronene, the cation bands corresponding to the CC modes are typically 2-5 times more intense than those of the CH out-of-plane bending vibrations. For the cations, the CC stretching and CH in-plane bending modes give rise to bands that are an order of magnitude stronger than those of the neutral species, and the CH out-of-plane bends produce bands that are 5-20 times weaker than those of the neutral species. This behavior is similar to that found in most other PAH cations studied to date. The astronomical implications of these PAH cation spectra are also discussed.
A pyrene-benzthiazolium conjugate portraying aggregation induced emission, a ratiometric detection and live cell visualization of HSO3(.).

PubMed

Diwan, Uzra; Kumar, Virendra; Mishra, Rakesh K; Rana, Nishant Kumar; Koch, Biplob; Singh, Manish Kumar; Upadhyay, K K

2016-07-27

The present study deals with the photophysical property of a pyrene-benzthiazolium conjugate R1, as a strong intramolecular charge transfer (ICT) probe exhibiting long wavelength emission in the red region. Unlike traditional planar polyaromatic hydrocarbons whose aggregation generally quenches the light emission, the pyrene based R1 was found to display aggregation-induced emission (AIE) property along with simultaneous increase in its quantum yield upon increasing the water content of the medium. The R1 exhibits high specificity towards HSO3(-)/SO3(2-) by interrupting its own ICT producing there upon a large ratiometric blue shift of ∼220 nm in its emission spectrum. The lowest detection limit for the above measurement was found to be 8.90 × 10(-8) M. The fluorescent detection of HSO3(-) was also demonstrated excellently by test paper strip and silica coated TLC plate incorporating R1. The live cell imaging of HSO3(─) through R1 in HeLa cells was studied using fluorescence microscopic studies. The particle size and morphological features of R1 and R1-HSO3(-) aggregates in aqueous solution were characterized by DLS along with SEM analysis. Copyright © 2016 Elsevier B.V. All rights reserved.
Glowing locked nucleic acids: brightly fluorescent probes for detection of nucleic acids in cells.

PubMed

Østergaard, Michael E; Cheguru, Pallavi; Papasani, Madhusudhan R; Hill, Rodney A; Hrdlicka, Patrick J

2010-10-13

Fluorophore-modified oligonucleotides have found widespread use in genomics and enable detection of single-nucleotide polymorphisms, real-time monitoring of PCR, and imaging of mRNA in living cells. Hybridization probes modified with polarity-sensitive fluorophores and molecular beacons (MBs) are among the most popular approaches to produce hybridization-induced increases in fluorescence intensity for nucleic acid detection. In the present study, we demonstrate that the 2'-N-(pyren-1-yl)carbonyl-2'-amino locked nucleic acid (LNA) monomer X is a highly versatile building block for generation of efficient hybridization probes and quencher-free MBs. The hybridization and fluorescence properties of these Glowing LNA probes are efficiently modulated and optimized by changes in probe backbone chemistry and architecture. Correctly designed probes are shown to exhibit (a) high affinity toward RNA targets, (b) excellent mismatch discrimination, (c) high biostability, and (d) pronounced hybridization-induced increases in fluorescence intensity leading to formation of brightly fluorescent duplexes with unprecedented emission quantum yields (Φ(F) = 0.45-0.89) among pyrene-labeled oligonucleotides. Finally, specific binding between messenger RNA and multilabeled quencher-free MBs based on Glowing LNA monomers is demonstrated (a) using in vitro transcription assays and (b) by quantitative fluorometric assays and direct microscopic observation of probes bound to mRNA in its native form. These features render Glowing LNA as promising diagnostic probes for biomedical applications.
[Determination of benzo(alpha)pyrene in food with microwave-assisted extraction].

PubMed

Zhou, Na; Luo, He-Dong; Li, Na; Li, Yao-Qun

2014-03-01

Coupling derivative technique and constant-energy synchronous fluorescence scanning technique, a method of determining benzo[alpha] pyrene in foods by second derivative constant-energy synchronous spectrofluorimetry after microwave-assisted treatment of samples was established using domestic microwave oven. The main factors of influencing the efficiency of microwave extraction were discussed, including the extraction solvent types and amounts, the microwave extraction time, microwave radiation power and cooling time. And the comparison with ultrasonic extraction was made. Low-fat food samples, which were just microwave-extracted with mixed-solvents, could be analyzed immediately by the spectrofluorimetric technique. For high-fat food samples, microwave-assisted saponification and extraction were made at the same time, thus simplifying operation steps and reducing sample analysis time. So the whole sample analysis process could be completed within one hour. This method was simple, rapid and inexpensive. In consequence, it was applied to determine benzo(a)pyrene in food with good reproducibility and the recoveries of benzo(alpha) pyrene ranged from 90.0% to 105.0% for the low fat samples and 83.3% to 94.6% for high-fat samples.
Long-Range (Forster) Electronic Energy Transfer: A Laboratory Experiment.

ERIC Educational Resources Information Center

Berkovic, G.

1984-01-01

An experiment which measures the steady-state fluorescence of pyrene (the donor) in the presence of varying concentrations of acridine orange (the acceptor) in ethyline glycol solutions is described. Background information, equipment needed, and procedures used are included. (JN)
Boron-rich benzene and pyrene derivatives for the detection of thermal neutrons

PubMed Central

Yemam, Henok A.; Mahl, Adam; Koldemir, Unsal; Remedes, Tyler; Parkin, Sean; Greife, Uwe; Sellinger, Alan

2015-01-01

A synthetic methodology is developed to generate boron rich aromatic small molecules based on benzene and pyrene moieties for the detection of thermal neutrons. The prepared aromatic compounds have a relatively high boron content up to 7.4 wt%, which is important for application in neutron detection as 10B (20% of natural abundance boron) has a large neutron induced reaction cross-section. This is demonstrated by preparing blends of the synthesized molecules with fluorescent dopants in poly(vinyltoluene) matrices resulting in comparable scintillation light output and neutron capture as state-of-the art commercial scintillators, but with the advantage of much lower cost. The boron-rich benzene and pyrene derivatives are prepared by Suzuki conditions using both microwave and traditional heating, affording yields of 40–93%. This new procedure is simple and straightforward, and has the potential to be scaled up. PMID:26334111
Multiprobe Spectroscopic Inverstigation of Molecular-level Behavior within Aqueous 1-Butyl-3-methylimidazolium Tetrafluoroborate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, Abhra; Ali, Maroof; Baker, Gary A

2009-01-01

In this work, an array of molecular-level solvent featuressincluding solute-solvent/solvent-solvent interactions, dipolarity, heterogeneity, dynamics, probe accessibility, and diffusionswere investigated across the entire composition of ambient mixtures containing the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4], and pH 7.0 phosphate buffer, based on results assembled for nine different molecular probes utilized in a range of spectroscopic modes. These studies uncovered interesting and unusual solvatochromic probe behavior within this benchmark mixture. Solvatochromic absorbance probessa watersoluble betaine dye (betaine dye 33), N,N-diethyl-4-nitroaniline, and 4-nitroanilineswere employed to determine ET (a blend of dipolarity/polarizability and hydrogen bond donor contributions) and the Kamlet-Taft indices * (dipolarity/polarizability), R (hydrogenmore » bond donor acidity), and (hydrogen bond acceptor basicity) characterizing the [bmim][BF4] + phosphate buffer system. These parameters each showed a marked deviation from ideality, suggesting selective solvation of the individual probe solutes by [bmim][BF4]. Similar conclusions were derived from the responses of the fluorescent polarity-sensitive probes pyrene and pyrene-1-carboxaldehyde. Importantly, the fluorescent microfluidity probe 1,3-bis(1-pyrenyl)propane senses a microviscosity within the mixture that significantly exceeds expectations derived from simple interpolation of the behavior in the neat solvents. On the basis of results from this probe, a correlation between microviscosity and bulk viscosity was established; pronounced solvent-solvent hydrogen-bonding interactions were implicit in this behavior. The greatest deviation from ideal additive behavior for the probes studied herein was consistently observed to occur in the buffer-rich regime. Nitromethane-based fluorescence quenching of pyrene within the [bmim][BF4] + phosphate buffer system showed unusual compliance with a sphere-of-action quenching model, a further manifestation of the microheterogeneity of the system. Fluorescence correlation spectroscopic results for both small (BODIPY FL) and macromolecular (Texas Red-10 kDa dextran conjugate) diffusional probes provide additional evidence in support of microphase segregation inherent to aqueous [bmim][BF4].« less

Critical aggregates concentration of fatty esters present in biodiesel determined by turbidity and fluorescence.

PubMed

Froehner, Sandro; Sánez, Juan; Dombroski, Luiz Fernando; Gracioto, Maria Paula

2017-09-01

Biodiesel for combustible engine is available as mixture of fossil diesel and fatty esters obtained by transesterification of vegetable oils. The use of biodiesel reduces the amount of SO x , mainly. However, it was already observed that biodiesel has a different behavior in environment in cases of accidental spill and groundwater contamination. It was noticed that the biodegradation of hydrocarbons (cyclic and aliphatic) in the presence of biodiesel are speeded, although the mechanism is still unclear. Considering the chemical structure of fatty esters, it was investigated the formation of aggregates in water solution by fatty esters present in commercial biodiesel. In Brazil, biodiesel is composed by 95% of fossil diesel and 5% of fatty esters mixture. In this work, fatty esters were treated as neutral surfactant, i.e., it was treated as a molecule with polar and non-polar part. Turbidity and fluorescence were used to determine the critical aggregates concentration (CAC). Water solutions containing fatty esters were examined exploiting changes in turbidity and fluorescence intensity of pyrene. Abrupt changes were attributed to aggregates formation, following the same behavior of traditional amphiphilic compounds. It was determined the CAC for ethyl palmitate, ethyl stearate, ethyl oleate, and ethyl linoleate. The values of CAC for fatty esters varied from 1.91 to 4.27 μmol/L, while CAC for the mixture of esters (biodiesel) was 2.01 for methyl esters and 1.19 for ethyl esters, both prepared using soybean oil. The aggregates formation was also determined by fluorescence measurements considering the changes in intensity of peaks I and III of pyrene. Pyrene senses the changes in environment polarity. The values found of CAC by fluorescence for individual ethyl esters varied from 1.85 to 3.21 μmol/L, while mixtures of ethyl esters was 2.23 and 2.07 μmol/L for mixture of methyl esters. The results clearly showed that fatty esters form aggregates and might be responsible for speed degradation of compounds by accommodation of them in inner part of aggregates.
Fluorescent Binary Ensemble Based on Pyrene Derivative and Sodium Dodecyl Sulfate Assemblies as a Chemical Tongue for Discriminating Metal Ions and Brand Water.

PubMed

Zhang, Lijun; Huang, Xinyan; Cao, Yuan; Xin, Yunhong; Ding, Liping

2017-12-22

Enormous effort has been put to the detection and recognition of various heavy metal ions due to their involvement in serious environmental pollution and many major diseases. The present work has developed a single fluorescent sensor ensemble that can distinguish and identify a variety of heavy metal ions. A pyrene-based fluorophore (PB) containing a metal ion receptor group was specially designed and synthesized. Anionic surfactant sodium dodecyl sulfate (SDS) assemblies can effectively adjust its fluorescence behavior. The selected binary ensemble based on PB/SDS assemblies can exhibit multiple emission bands and provide wavelength-based cross-reactive responses to a series of metal ions to realize pattern recognition ability. The combination of surfactant assembly modulation and the receptor for metal ions empowers the present sensor ensemble with strong discrimination power, which could well differentiate 13 metal ions, including Cu 2+ , Co 2+ , Ni 2+ , Cr 3+ , Hg 2+ , Fe 3+ , Zn 2+ , Cd 2+ , Al 3+ , Pb 2+ , Ca 2+ , Mg 2+ , and Ba 2+ . Moreover, this single sensing ensemble could be further applied for identifying different brands of drinking water.
Organization and dynamics of pyrene and pyrene lipids in intact lipid bilayers. Photo-induced charge transfer processes.

PubMed Central

Barenholz, Y; Cohen, T; Korenstein, R; Ottolenghi, M

1991-01-01

The dynamics of fluorescence quenching and the organization of a series of pyrene derivatives anchored in various depths in bilayers of phosphatidylcholine small unilamellar vesicles was studied and compared with their behavior in homogeneous solvent systems. The studies include characterization of the environmental polarity of the pyrene fluorophore based on its vibronic peaks, as well as the interaction with three collisional quenchers: the two membrane-soluble quenchers, diethylaniline and bromobenzene, and the water soluble quencher potassium iodide. The system of diethylaniline-pyrene derivatives in the membrane of phosphatidylcholine vesicles was characterized in detail. The diethylaniline partition coefficient between the lipid bilayers and the buffer is approximately 5,800. Up to a diethylaniline/phospholipid mole ratio of 1:3 the perturbation to membrane structure is minimal so that all photophysical studies were performed below this mole ratio. The quenching reaction, in all cases, was shown to take place in the lipid bilayer interior and the relative quenching efficiencies of the various probe molecules was used to provide information on the distribution of both fluorescent probes and quencher molecules in the lipid bilayer. The quenching efficiency by diethylaniline in the lipid bilayer was found to be essentially independent on the length of the methylene chain of the pyrene moiety. These findings suggest that the quenching process, being a diffusion controlled reaction, is determined by the mobility of the diethylaniline quencher (with an effective diffusion coefficient D approximately 10(-7) cm2 s-1) which appears to be homogeneously distributed throughout the lipid bilayer. The pulsed laser photolysis products of the charge-transfer quenching reaction were examined. No exciplex (excited-complex) formation was observed and the yield of the separated radical ions was shown to be tenfold smaller than in homogenous polar solutions. The decay of the radical ions is considerably faster than the corresponding process in homogenous solutions. Relatively high intersystem crossing yields are observed. The results are explained on the basis of the intrinsic properties of a lipid bilayer, primarily, its rigid spatial organization. It is suggested that such properties favor ion-pair formation over exciplex generation. They also enhance primary geminate recombination of initially formed (solvent-shared) ion pairs. Triplet states are generated via secondary geminate recombination of ion pairs in the membrane interior. The results bear on the general mechanism of electron transfer processes in biomembranes. PMID:1883931
THE MICELLAR MODEL OF HUMIC ACID: EVIDENCE FROM PYRENE FLUORESCENCE MEASUREMENTS (R822832)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...
A specific chemodosimeter for fluoride ion based on a pyrene derivative with trimethylsilylethynyl groups.

PubMed

Lu, Hua; Wang, Qiuhong; Li, Zhifang; Lai, Guoqiao; Jiang, Jianxiong; Shen, Zhen

2011-06-21

Pyrene derivative 1 containing four trimethylsilylethynyl substituents was synthesized and investigated as a chromogenic and fluorescent chemodosimeter sensor for fluoride ions. 1 showed a high sensitivity and specific selectivity over a rapid response time toward fluoride anions compared to other anions, such as Cl(-), Br(-), ClO(4)(-), H(2)PO(4)(-) and HPO(4)(2-). TD-DFT calculations showed that the delocalization of the σ-electrons of the silicon destabilized the HOMO energy level of 1, thus red shifting both its absorption and emission spectrum. The addition of F(-) removed the trimethylsilyl substituents and resulted in a blue shift of both the absorption and fluorescent spectra of 1, which could be monitored by the color change with the naked-eye. Moreover, an easy to prepare test paper, which was obtained by immersing a filter paper into a THF solution of 1, could be utilized to detect and estimate the concentration of fluoride anions in water.
Liquid chromatographic determination of microcystins in water samples following pre-column excimer fluorescence derivatization with 4-(1-pyrene)butanoic acid hydrazide.

PubMed

Hayama, Tadashi; Katoh, Kenji; Aoki, Takayoshi; Itoyama, Miki; Todoroki, Kenichiro; Yoshida, Hideyuki; Yamaguchi, Masatoshi; Nohta, Hitoshi

2012-11-28

A method to measure the concentrations of microcystins (MCs) in water samples has been developed by incorporating pre-column fluorescence derivatization and liquid chromatography (LC). A solid-phase extraction for pretreatment was used to extract the MCs in water samples. The MCs were derivatized with excimer-forming 4-(1-pyrene)butanoic acid hydrazide (PBH). The MCs could then be detected by fluorescence after separation with a pentafluorophenyl (PFP)-modified superficially porous (core shell) particle LC column. The derivatization reactions of MCs with PBH proceeded easily in the presence of 4,6-dimethoxy-1,3,5-triazin-2-yl-4-methylmorpholinium (DMT-MM) as a condensation reagent, and the resulting derivatives could be easily separated on the PFP column. The derivatives were selectively detected at excimer fluorescence wavelengths (440-540 nm). The instrument detection limit and the instrument quantification limit of the MCs standards were 0.4-1.2 μg L(-1) and 1.4-3.9 μg L(-1), respectively. The method was validated at 0.1 and 1.0 μg L(-1) levels in tap and pond water samples, and the recovery of MCs was between 67 and 101% with a relative standard deviation of 11%. The proposed method can be used to quantify trace amounts of MCs in water samples. Copyright © 2012 Elsevier B.V. All rights reserved.
Mercury assisted fluorescent supramolecular assembly of hexaphenylbenzene derivative for femtogram detection of picric acid.

PubMed

Pramanik, Subhamay; Bhalla, Vandana; Kumar, Manoj

2013-09-02

Aggregates of hexaphenylbenzene derivatives 3, having pyrene groups form network of fluorescent nanofibres in presence of mercury ions. Further, fluorescent nanofibres of 3-Hg(2+) supramolecular ensemble exhibit sensitive and pronounced response towards the picric acid. In addition, the solution coated paper strips of 3-Hg(2+) supramolecular ensemble can detect picric acid in the range of 2.29 fg/cm(2), thus, providing a simple, portable and low cost method for detection of picric acid in solution and in contact mode. Copyright © 2013 Elsevier B.V. All rights reserved.
Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Hydrocarbon Cations

NASA Technical Reports Server (NTRS)

Hudgins, D. M.; Allamandola, L. J.

1995-01-01

Gaseous, ionized polycyclic aromatic hydrocarbons (PAHs) are thought to be responsible for a very common family of interstellar infrared emission bands. Here the near- and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to coronene: phenanthrene, pyrene, benzo(e)pyrene, benzo-(ghi)perylene, and coronene, are presented to test this hypothesis. For those molecules that have been studied previously (pyrene, pyrene-d(sub 10), and coronene), band positions and relative intensities are in agreement. In all of these cases we report additional features. Absolute integrated absorbance values are given for the phenanthrene, perdeuteriophenanthrene, pyrene, benzo(ghi]perylene, and coronene cations. With the exception of coronene, the cation bands corresponding to the CC modes are typically 2-5 times more intense than those of the CH out-of-plane bending vibrations. For the cations, the CC stretching and CH in-plane bending modes give rise to bands that are an order of magnitude stronger than those of the neutral species, and the CH out-of-plane bends produce bands that are 5-20 times weaker than those of the neutral species. This behavior is similar to that found in most other PAH cations studied to date. The astronomical implications of these PAH cation spectra are also discussed.
Radiation-chemical and optical properties of a radio-fluorogenic gel

NASA Astrophysics Data System (ADS)

Yao, Tiantian; Gasparini, Alessia; Denkova, Antonia G.; Warman, John M.

2015-01-01

The radiation-induced polymerization and fluorescence intensity of a radio- fluorogenic medium consisting of tertiary-butyl acrylate (TBA) with ca 100 ppm maleimido- pyrene (MPy) display a super-linear dependence on dose and a close to inverse square root dependence on dose rate over the range from 2 to 30 Gy/min. In contrast with the fluorescence, the clarity and optical absorption remain unchanged on irradiation up to at least 17% monomer conversion for which the medium is a rigid gel.
Kinetic stability and membrane structure of liposomes during in vitro infant intestinal digestion: Effect of cholesterol and lactoferrin.

PubMed

Liu, Weilin; Wei, Fuqiang; Ye, Aiqian; Tian, Mengmeng; Han, Jianzhong

2017-09-01

The effects of cholesterol and lactoferrin on the kinetic stability and membrane structural integrity of negatively charged liposomes under in vitro infant intestinal digestion conditions were elucidated using dynamic light scattering, pH-stat titration, Fourier transform infrared spectroscopy, and pyrene steady state fluorescence probes. The liposomes had a smaller particle diameter, a wider size distribution, and a greater negative charge after digestion. The incorporation of cholesterol into the phospholipid bilayers resulted in a more ordered conformation in the aliphatic tail region and reduced micropolarity, indicating that cholesterol can improve the structural stability of liposomal membranes against intestinal environmental stress. Lactoferrin coverage facilitated the release of free fatty acids and increased the microfluidity of the bilayers, reducing the structural integrity of the liposomes. This study provides useful information on the design of liposomes and other microcapsules with improved and controlled release properties during digestion for particular groups of people. Copyright © 2017 Elsevier Ltd. All rights reserved.
The effect of humic acids on biodegradation of polycyclic aromatic hydrocarbons depends on the exposure regime.

PubMed

Tejeda-Agredano, Maria-Carmen; Mayer, Philipp; Ortega-Calvo, Jose-Julio

2014-01-01

Binding of polycyclic aromatic hydrocarbons (PAHs) to dissolved organic matter (DOM) can reduce the freely dissolved concentration, increase apparent solubility or enhance diffusive mass transfer. To study the effects of DOM on biodegradation, we used phenanthrene and pyrene as model PAHs, soil humic acids as model DOM and a soil Mycobacterium strain as a representative degrader organism. Humic acids enhanced the biodegradation of pyrene when present as solid crystals but not when initially dissolved or provided by partitioning from a polymer. Synchronous fluorescence spectrophotometry, scintillation counting and a microscale diffusion technique were applied in order to determine the kinetics of dissolution and diffusive mass transfer of pyrene. We suggest that humic acids can enhance or inhibit biodegradation as a result of the balance of two opposite effects, namely, solubilization of the chemicals on the one hand and inhibition of cell adhesion to the pollutant source on the other. Copyright © 2013 Elsevier Ltd. All rights reserved.
Quercetin solubilisation in bile salts: A comparison with sodium dodecyl sulphate.

PubMed

Buchweitz, Maria; Kroon, Paul A; Rich, Gillian T; Wilde, Peter J

2016-11-15

To understand the bioaccessibility of the flavonoid quercetin we studied its interaction with bile salt micelles. The environmental sensitivity of quercetin's UV-visible absorption spectrum gave information about quercetin partitioning. Two quercetin absorption peaks gave complementary information: Peak A (240-280nm) on the intermicellar phase and Peak B (340-440nm) on the micellar phase. Thus, by altering pH, we showed that only non-ionised quercetin partitions into micelles. We validated our interpretation by studying quercetin's interaction with SDS micelles. Pyrene fluorescence and the quercetin UV-visible spectra show that the adsorption site for pyrene and quercetin in bile salt micelles is more hydrophobic than that for SDS micelles. Also, both quercetin and pyrene reported a higher critical micelle concentration for bile salts than for SDS. Our method of using a flavonoid as an intrinsic probe, is generally applicable to other lipophilic bioactives, whenever they have observable environmental dependent properties. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.
Bright and photostable push-pull pyrene dye visualizes lipid order variation between plasma and intracellular membranes.

PubMed

Niko, Yosuke; Didier, Pascal; Mely, Yves; Konishi, Gen-ichi; Klymchenko, Andrey S

2016-01-11

Imaging lipid organization in cell membranes requires advanced fluorescent probes. Here, we show that a recently synthesized push-pull pyrene (PA), similarly to popular probe Laurdan, changes the emission maximum as a function of lipid order, but outperforms it by spectroscopic properties. In addition to red-shifted absorption compatible with common 405 nm diode laser, PA shows higher brightness and much higher photostability than Laurdan in apolar membrane environments. Moreover, PA is compatible with two-photon excitation at wavelengths >800 nm, which was successfully used for ratiometric imaging of coexisting liquid ordered and disordered phases in giant unilamellar vesicles. Fluorescence confocal microscopy in Hela cells revealed that PA efficiently stains the plasma membrane and the intracellular membranes at >20-fold lower concentrations, as compared to Laurdan. Finally, ratiometric imaging using PA reveals variation of lipid order within different cellular compartments: plasma membranes are close to liquid ordered phase of model membranes composed of sphingomyelin and cholesterol, while intracellular membranes are much less ordered, matching well membranes composed of unsaturated phospholipids without cholesterol. These differences in the lipid order were confirmed by fluorescence lifetime imaging (FLIM) at the blue edge of PA emission band. PA probe constitutes thus a new powerful tool for biomembrane research.
Assessing phototoxicity of petroleum using the bivalve Mulinia lateralis and the mysid Mysidopsis bahia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pelletier, M.; Champlin, D.; Burgess, R.

1995-12-31

One of the major inputs of PAHs in the marine environment is petroleum products. A large and often catastrophic source of petroleum is an oil spill, which releases concentrated quantities of PAHs into the water column. Intermediate molecular weight compounds remain in the water column for a relatively extended length of time. These compounds include phototoxic PAHs such as anthracene, fluoranthene, pyrene, and their substituted derivatives. Assessments of the environmental impact of marine oil spills have not included phototoxicity tests using pelagic larvae of benthic invertebrates. In this study, the photoreactive toxicity of individual PAHs, including anthracene, pyrene, and fluoranthene,more » were determined using the bivalve, Mulinia lateralis and the mysid, Mysidopsis bahia. Ultraviolet light exposures increased toxicity relative to fluorescent light for both species but a particularly dramatic response was seen using M. lateralis embryos. This species was relatively insensitive when exposed under fluorescent lights, but exhibited up to a 4,000 fold increase in toxicity under ultraviolet lights. Exposures with different types of petroleum (e.g., fuel oil {number_sign}2 and crude oil) under fluorescent and ultraviolet light will demonstrate the utility of this bivalve and mysid for assessing oil spill-related acute and sublethal toxicity in the marine environment.« less
Determination of benzo[a]pyrene in edible oils using phase-transfer-catalyst-assisted saponification and supramolecular solvent microextraction coupled to HPLC with fluorescence detection.

PubMed

Wang, Jin; Liu, Laping; Shi, Ludi; Yi, Tingquan; Wen, Yuxia; Wang, Juanli; Liu, Shuhui

2017-01-01

For the analysis of edible oils, saponification is well known as a useful method for eliminating oil matrices. The conventional approach is conducted with alcoholic alkali; it consumes a large volume of organic solvents and impedes the retrieval of analytes by microextraction. In this study, a low-organic-solvent-consuming method has been developed for the analysis of benzo[a]pyrene in edible oils by high-performance liquid chromatography with fluorescence detection. Sample treatment involves aqueous alkaline saponification, assisted by a phase-transfer catalyst, and selective in situ extraction of the analyte with a supramolecular solvent. Comparison of the chromatograms of the oil extracts obtained by different microextraction methods showed that the supramolecular solvent has a better clean-up effect for the unsaponifiable matter from oil matrices. The method offered excellent linearity over a range of 0.03- 5.0 ng mL -1 (r > 0.999). Recovery rates varied from 94 to 102% (RSDs <5.0%). The detection limit and quantification limit were 0.06 and 0.19 μg kg -1 , respectively. The proposed method was applied for the analysis of 52 edible oils collected online in China; the analyte contents of 23 tested oil samples exceeded the maximum limit of 2 μg kg -1 for benzo[a]pyrene set by the Commission Regulation of the European Union. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Temperature effect on pyrene as a polarity probe for supercritical fluid and liquid solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, H.H.; McGuffin, V.L.

1994-05-01

The effect of temperature on the fluorescence spectrum of pyrene in supercritical and liquid carbon dioxide and liquid organic solvents is systematically studied. The Py parameter (intensity ratio of vibronic bands 1 and 3) is found to increase with the density of supercritical carbon dioxide in the range from 0.54 to 0.75 g/cm{sup 3}. This observation is consistent with the fact that dispersion forces which represent the major interaction between pyrene and carbon dioxide, depend inversely on the sixth power of distance. However, the Py parameter of both supercritical and liquid carbon dioxide is also found to decrease with temperaturemore » at constant density, which is not consistent with expectations for dispersion forces. Carbon dioxide, which is generally regarded as a nonpopular solvent, shows a temperature effect comparable to that for polar liquid solvents. The origin of this temperature effect is examined in this study by computer simulation using both semispherical molecular orbital and molecular mechanic methods. On the basis of these simulations, a strong electrostatic attraction arises between pyrene and carbon dioxide which is similiar in magnitude to that with polar solvents. The temperature dependence of the Py parameter can be qualitatively explained by these simulation results. 45 refs., 15 fig., 5 tab.« less
Baseline concentrations of biliary PAH metabolites in perch (Perca fluviatilis) in the open Gulf of Finland and in two coastal areas

NASA Astrophysics Data System (ADS)

Vuorinen, Pekka J.; Saulamo, Kari; Lecklin, Tiina; Rahikainen, Mika; Koivisto, Pertti; Keinänen, Marja

2017-07-01

Female perch (Perca fluviatilis) were sampled annually in late summer from 2006 to 2009 from the open sea of the eastern Gulf of Finland off Haapasaari island to monitor baseline biliary PAH metabolite concentrations. In addition, two coastal locations were sampled in 2008. PAH metabolite concentrations were compared between the open sea and coastal samples and between the sampling years and examined in relation to the body characteristics of perch. Of the PAH metabolites, only 1-hydroxypyrene (1-OH pyrene) was detected at quantifiable levels in the bile of nearly all perch individuals. There were some annual differences but no temporal trend in the concentration of biliary 1-OH pyrene in perch from Haapasaari. At the coastal locations, 1-OH pyrene concentrations in the bile of perch were significantly higher than in the open sea Haapasaari area, probably due to greater contamination of the coastal sites and differences in feeding behaviour. No correlations between the body characteristics of perch and 1-OH pyrene concentrations were detected. It is concluded that PAH metabolites in the bile of fish could be measured in the Gulf of Finland to detect oil spills in the open sea, and the cost-effective total fluorescence method could be used in such monitoring programmes.
Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Hydrocarbon Cations. Part 2; The Members of the Thermodynamically Most Favorable Series through Coronene

NASA Technical Reports Server (NTRS)

Hudgins, D. M.; Allamandola, L. J.

1995-01-01

Gaseous, ionized polycyclic aromatic hydrocarbons (PAHS) are thought to be responsible for a very common family of interstellar infrared emission bands. Here the near- and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to coronene: phenanthrene, pyrene, benzo[e]pyrene, benzo-[ghi]perylene, and coronene, are presented to test this hypothesis. For those molecules that have been studied previously (pyrene, pyrene-d(sub 10), and coronene), band positions and relative intensities are in agreement. In all of these cases we report additional features. Absolute integrated absorbance values are given for the phenanthrene, perdeuteriophenanthrene, pyrene, benzo[ghi]perylene, and coronene cations. With the exception of coronene, the cation bands corresponding to the CC modes are typically 2-5 times more intense than those of the CH out-of-plane bending vibrations. For the cations, the CC stretching and CH in-plane bending modes give rise to bands that are an order of magnitude stronger than those of the neutral species, and the CH out-of-plane bends produce bands that are 5-20 times weaker than those of the neutral species. This behavior is similar to that found in most other PAH cations studied to date. The astronomical implications of these PAH cation spectra are also discussed.
A novel ''donor-π-acceptor'' type fluorescence probe for sensing pH: mechanism and application in vivo.

PubMed

Chao, Jianbin; Wang, Huijuan; Zhang, Yongbin; Yin, Caixia; Huo, Fangjun; Song, Kailun; Li, Zhiqing; Zhang, Ting; Zhao, Yaqin

2017-11-01

A novel pH fluorescent probe 1-(pyren-1-yl)-3-(6-methoxypridin-3-yl)-acrylketone, (PMPA), which had a pyrene structure attached to methoxypyridine, was synthesized for monitoring extremely acidic and alkaline pH. The pH titrations indicated that PMPA displayed a remarkable emission enhancement with a pK a of 2.70 and responded linearly to minor pH fluctuations within the extremely acidic range of 1.26-3.97. Interestingly, PMPA also exhibited strong pH-dependent characteristics with pK a 9.32 and linear response to extreme-alkalinity range of 8.54-10.36. In addition, PMPA displayed a good selectivity, excellent photostability and large Stokes shift (167nm). Furthermore, the probe PMPA had excellent cell membrane permeability and was applied successfully to rapidly detect pH in living cells. pH value in these organs was closely related to many diseases, so these findings suggested that the probe had potential application in pH detecting for disease diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.
Synthesis of three new thiophene condensed pyrene derivatives, crystal structure and evaluation of their photophysical properties

NASA Astrophysics Data System (ADS)

Moriguchi, Tetsuji; Yakeya, Daisuke; Tsuge, Akihiko; Jalli, Venkataprasad

2018-04-01

Three new thiophene condensed fluorescent pyrene derivatives have been synthesized by a two-step process, via. Wittig reaction followed by iodine promoted photocyclization. These molecules have been characterized by 1H NMR and EI-MS. Further, the molecular structures of 4a, 4b and 4c has been confirmed by single crystal X-ray diffraction analysis. The protons located in the fjord and cove-regions of molecules 4b and 4c showed downfield shifts of the protons. Molecule 4a crystallized under monoclinic system with space group P21/c, molecule 4b crystallized under monoclinic system with space group C2/c and the molecule 4c crystalized under triclinic system with space group P-1. Molecules 4a, 4b and 4c showed strong absorption maxima wavelengths at 305, 358 and 330 nm, respectively. The molar extinctinction coefficients (ε) of the compounds 4a, 4b and 4c indicated molecule 4c has better ability to absorb UV light, molecule 4b has better fluorescence intensity than molecule 4a and 4c.

Micelles for the self-assembly of "off-on-off" fluorescent sensors for pH windows.

PubMed

Diaz-Fernandez, Yuri; Foti, Francesco; Mangano, Carlo; Pallavicini, Piersandro; Patroni, Stefano; Perez-Gramatges, Aurora; Rodriguez-Calvo, Simon

2006-01-11

A micellar approach is proposed to build a series of systems featuring an "off-on-off" fluorescent window response with changes in pH. The solubilizing properties of micelles are used to self-assemble, in water, plain pyrene with lipophilized pyridine and tertiary amine moieties. Since these components are contained in the small volume of the same micelle, pyrene fluorescence is influenced by the basic moieties: protonated pyridines and free tertiary amines behave as quenchers. Accordingly, fluorescence transitions from the "off" to the "on" state, and viceversa, take place when the pH crosses the pK(a) values of the amine and pyridine fragments. To obtain an "off-on-off" fluorescent response in this investigation we use either a set of dibasic lipophilic molecules (containing covalently linked pyridine and tertiary amine groups) or combinations of separate, lipophilic pyridines and tertiary amines. The use of combinations of dibasic and monobasic lipophilic molecules also gives a window-shaped fluorescence response with changes in pH: it is the highest pyridine pK(a) and the lowest tertiary amine pK(a) that determine the window limits. The pK(a) values of all the examined lipophilic molecules were determined in micelles, and compared with the values found for the same molecules in solvent mixtures in which they are molecularly dispersed. The effect of micellization is to significantly lower the observed protonation constants of the lipophilized species. Moreover, the more lipophilic a molecule is, the lower the observed logK value is. Accordingly, changing the substituents on the basic moieties or modifying their structure, tuning the lipophilicity of the mono- or dibases, and choosing among a large set of possible combination of lipophilized mono- and dibases have allowed us to tune, almost at will, both the width and the position along the pH axis of the obtained fluorescent window.
Transfer of benzo[a]pyrene from microplastics to Artemia nauplii and further to zebrafish via a trophic food web experiment: CYP1A induction and visual tracking of persistent organic pollutants.

PubMed

Batel, Annika; Linti, Frederic; Scherer, Martina; Erdinger, Lothar; Braunbeck, Thomas

2016-07-01

The uptake of microplastic particles and the transfer of potential harmful substances along with microplastics has been studied in a variety of organisms, especially invertebrates. However, the potential accumulation of very small microplastic particles along food webs ending with vertebrate models has not been investigated so far. Therefore, a simple artificial food chain with Artemia sp. nauplii and zebrafish (Danio rerio) was established to analyze the transfer of microplastic particles and associated persistent organic pollutants (POPs) between different trophic levels. Very small (1-20 μm) microplastic particles accumulated in Artemia nauplii and were subsequently transferred to fish. Virgin particles not loaded with POPs did not cause any observable physical harm in the intestinal tracts of zebrafish, although parts of the particles were retained within the mucus of intestinal villi and might even have been taken up by epithelial cells. The transfer of associated POPs was tested with the polycyclic aromatic hydrocarbon benzo[a]pyrene and an ethoxyresorufin-O-deethylase (EROD) assay for CYP1A induction in zebrafish liver as well as via fluorescence analyses. Whereas a significant induction in the EROD assay could not be shown, because of high individual variation and low sensitivity regarding substance concentration, the fluorescence tracking of benzo[a]pyrene indicates that food-borne microplastic-associated POPs may actually desorb in the intestine of fish and are thus transferred to the intestinal epithelium and liver. Environ Toxicol Chem 2016;35:1656-1666. © 2016 SETAC. © 2016 SETAC.
Infrared Spectroscopy of Polycyclic Aromatic Hydrocarbon Cations. 3; The Members

NASA Technical Reports Server (NTRS)

Hudgins, D. M.; Allamandola, L. J.; Wittebon, Fred C. (Technical Monitor)

1994-01-01

In spite of the fact that the infrared spectroscopic properties of only a few isolated ionized polycyclic aromatic hydrocarbons (PAHs) are known, gaseous, ionized PAHs are thought to be responsible for a very common family of infrared interstellar emission bands. In order to provide a data base to test this hypothesis and, if borne out, to use this emission band family as a probe of many different interstellar environments, we are carrying out a thorough study of the infrared spectroscopic properties of neutral and ionized PAHs in argon matrices. Here we present the near and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to coronene: phenanthrene, pyrene, benzo[e]pyrene, benzo[ghilperylene, and coronene. The properties of naphthalene, the first member of the series, are given elsewhere. The spectra of perdeuterated phenanthrene and pyrene are also reported. For those molecules which have been previously studied (pyrene, d(10)-pyrene, and coronene), band positions and relative intensities are in agreement. In all cases we report additional features. Absolute integrated absorbance values are given for the phenanthrene, perdeutero-phenanthrene, pyrene, benzo[ghi]perylene, and coronene cations. With the exception of coronene,the cation bands corresponding to the CC modes are typically 2-5 times more intense than those of the CH out-of-plane bending vibrations. For the cations the CC stretching and CH in-plane bending modes give rise to bands which are an order of magnitude stronger than for the neutral species, and the CH out-of-plane bends produce bands which are 5-20 times weaker than in the neutral species. This behavior is similar to that found in most other PAH cations studied to date. The astronomical implications of these PAH cation spectra are also discussed.
Excited state proton transfer in the lysosome of live lung cells: normal and cancer cells.

PubMed

Chowdhury, Rajdeep; Saha, Abhijit; Mandal, Amit Kumar; Jana, Batakrishna; Ghosh, Surajit; Bhattacharyya, Kankan

2015-02-12

Dynamics of excited state proton transfer (ESPT) in the lysosome region of live lung cells (normal and cancer) is studied by picosecond time-resolved confocal microscopy. For this, we used a fluorescent probe, pyranine (8-hydroxy-pyrene-1,3,6-trisulfonate, HPTS). From the colocalization of HPTS with a lysotracker dye (lysotracker yellow), we confirmed that HPTS resides in the lysosome for both of the cells. The diffusion coefficient (Dt) in the lysosome region was obtained from fluorescence correlation spectroscopy (FCS). From Dt, the viscosity of lysosome is estimated to be ∼40 and ∼30 cP in the cancer and normal cells, respectively. The rate constants of the elementary steps of ESPT in a normal lung cell (WI38) are compared with those in a lung cancer cell (A549). It is observed that the time constant of the initial proton transfer process in a normal cell (τ(PT) = 40 ps) is similar to that in a cancer cell. The recombination of the geminate ion pair is slightly faster (τ(rec) = 25 ps) in the normal cell than that (τ(rec) = 30 ps) in a cancer cell. The time constant of the dissociation (τ(diss)) of the geminate ion pair for the cancer cell (τ(diss) = 80 ps) is 1.5 times faster compared to that (τ(diss) = 120 ps) in a normal cell.
Successive Mineralization and Detoxification of Benzo[a]pyrene by the White Rot Fungus Bjerkandera sp. Strain BOS55 and Indigenous Microflora

PubMed Central

Kotterman, Michiel J. J.; Vis, Eric H.; Field, Jim A.

1998-01-01

White rot fungi can oxidize high-molecular-weight polycyclic aromatic hydrocarbons (PAH) rapidly to polar metabolites, but only limited mineralization takes place. The objectives of this study were to determine if the polar metabolites can be readily mineralized by indigenous microflora from several inoculum sources, such as activated sludge, forest soils, and PAH-adapted sediment sludge, and to determine if such metabolites have decreased mutagenicity compared to the mutagenicity of the parent PAH. 14C-radiolabeled benzo[a]pyrene was subjected to oxidation by the white rot fungus Bjerkandera sp. strain BOS55. After 15 days, up to 8.5% of the [14C]benzo[a]pyrene was recovered as 14CO2 in fungal cultures, up to 73% was recovered as water-soluble metabolites, and only 4% remained soluble in dibutyl ether. Thin-layer chromatography analysis revealed that many polar fluorescent metabolites accumulated. Addition of indigenous microflora to fungal cultures with oxidized benzo[a]pyrene on day 15 resulted in an initially rapid increase in the level of 14CO2 recovery to a maximal value of 34% by the end of the experiments (>150 days), and the level of water-soluble label decreased to 16% of the initial level. In fungal cultures not inoculated with microflora, the level of 14CO2 recovery increased to 13.5%, while the level of recovery of water-soluble metabolites remained as high as 61%. No large differences in 14CO2 production were observed with several inocula, showing that some polar metabolites of fungal benzo[a]pyrene oxidation were readily degraded by indigenous microorganisms, while other metabolites were not. Of the inocula tested, only PAH-adapted sediment sludge was capable of directly mineralizing intact benzo[a]pyrene, albeit at a lower rate and to a lesser extent than the mineralization observed after combined treatment with white rot fungi and indigenous microflora. Fungal oxidation of benzo[a]pyrene resulted in rapid and almost complete elimination of its high mutagenic potential, as observed in the Salmonella typhimurium revertant test performed with strains TA100 and TA98. Moreover, no direct mutagenic metabolite could be detected during fungal oxidation. The remaining weak mutagenic activity of fungal cultures containing benzo[a]pyrene metabolites towards strain TA98 was further decreased by subsequent incubations with indigenous microflora. PMID:9687440
Naphtyl- and pyrenyl-flavylium dyads: Synthesis, DFT and optical properties

NASA Astrophysics Data System (ADS)

Aguilar-Castillo, Bethsy Adriana; Sánchez-Bojorge, Nora Aydee; Chávez-Flores, David; Camacho-Dávila, Alejandro A.; Pasillas-Ornelas, Eddie; Rodríguez-Valdez, Luz-María; Zaragoza-Galán, Gerardo

2018-03-01

A one-step preparation of flavylium salts containing naphtyl and pyrenyl moieties is described hereafter. Flavylium salts were successfully characterized by 1H NMR spectroscopy and ESI-MS spectrometry. Theoretical calculations were carried out by means of Density Functional Theory in order to simulate flavylium cation electronic transitions. Molecular simulation of -naphtyl derivatives displayed a coplanar conformation between naphthalene and benzopyrylium moieties. In contrast, DFT analysis exhibited a non-coplanar arrangement of pyrene and benzopyrylium units. These former statements in coherence with the absorption experiments where the naphtyl-flavylium dyads shows a red-shifted maximum absorption band with respect to pyrene dyads, led us to conclude that these bathochromic effects are associated with a more planar conformation.
Measurement and Analysis of in vitro Actin Polymerization

PubMed Central

Doolittle, Lynda K.; Rosen, Michael K.; Padrick, Shae B.

2014-01-01

Summary The polymerization of actin underlies force generation in numerous cellular processes. While actin polymerization can occur spontaneously, cells maintain control over this important process by preventing actin filament nucleation and then allowing stimulated polymerization and elongation by several regulated factors. Actin polymerization, regulated nucleation and controlled elongation activities can be reconstituted in vitro, and used to probe the signaling cascades cells use to control when and where actin polymerization occurs. Introducing a pyrene fluorophore allows detection of filament formation by an increase in pyrene fluorescence. This method has been used for many years and continues to be broadly used, owing to its simplicity and flexibility. Here we describe how to perform and analyze these in vitro actin polymerization assays, with an emphasis on extracting useful descriptive parameters from kinetic data. PMID:23868594
Spirolactone and spirothiolactone rhodamine-pyrene probes for detection of Hg2 + with different sensing properties and its application in living cells

NASA Astrophysics Data System (ADS)

Rui, Qing-Qing; Zhou, Yi; Fang, Yuan; Yao, Cheng

2016-04-01

Two new rhodamine B-based fluorescent probes PyRbS and PyRbO containing pyrene moiety were designed and synthesized. Both of the probes showed colorimetric and fluorometric sensing abilities for Hg2 + with high selectivity over other metal ions. The binding analysis using Job's plot suggested 1:1 stoichiometry for the complexes formed for Hg2 +. Compared with PyRbO, the PyRbS showed higher selectivity and sensitivity due to the thiophilic property of Hg2 + ion. The PyRbS exhibited the linear fluorescence quenching to Hg2 + in the range of 0.3 to 4.8 μM (λex = 365 nm) and 0.3 to 5.4 μM (λex = 515 nm), and the detection limit was 0.72 μM. Moreover, ratiometric changes of PyRbS with Hg2 + in absorption spectrum were observed, which could not be obtained in the combination of PyRbO with Hg2 +. In addition, the methyl thiazolyl tetrazolium (MTT) assay demonstrated that RbPyS had low cytotoxicity and was successfully used to monitor intracellular Hg2 + levels in living cells.
A New Route to Liposil Formation by an Interfacial Sol-Gel Process Confined by Lipid Bilayer.

PubMed

Shen, Shukun; Yang, Lu; Lu, Yaxing; Chen, Jian-Gang; Song, Shaofei; Hu, Daodao; Parikh, Atul

2015-11-18

We report a new and simple approach to prepare a class of silica-reinforced liposomes with hybrid core-shell nanostructures. The amphiphilic natural structure of lipids was exploited to sequester hydrophobic molecules, namely precursor TEOS and pyrene, in the hydrophobic midplane of liposomal bilayer assemblies in the aqueous phase. Subsequent interfacial hydrolysis of TEOS at the bilayer/water interface and ensuing condensation within the hydrophobic interstices of the lipid bilayer drives silica formation in situ, producing a novel class of silica-lipid hybrid liposils. Structural characterization by scanning- and transmission electron microscopy confirm that the liposils so generated preserve closed topologies and size-monodipersity of the parent lecithin liposomes, and DSC-TGA and XRD measurements provide evidence for the silica coating. Monitoring fluorescence measurements using embedded pyrene yield detailed information on microenvironment changes, which occur during sol-gel process and shed light on the structural evolution during silica formation. We envisage that liposils formed by this simple, new approach, exploiting the hydrophobic core of the lipid bilayer to spatially localize silica-forming precursors enables preparation of stable liposils exhibiting capacity for cargo encapsulation, bicompatibility, and fluorescence monitoring, more generally opening a window for construction of stable, functional hybrid materials.
Light-responsive micelles of spiropyran initiated hyperbranched polyglycerol for smart drug delivery.

PubMed

Son, Suhyun; Shin, Eeseul; Kim, Byeong-Su

2014-02-10

Light-responsive polymeric micelles have emerged as site-specific and time-controlled systems for advanced drug delivery. Spiropyran (SP), a well-known photochromic molecule, was used to initiate the ring-opening multibranching polymerization of glycidol to afford a series of hyperbranched polyglycerols (SP-hb-PG). The micelle assembly and disassembly were induced by an external light source owing to the reversible photoisomerization of hydrophobic SP to hydrophilic merocyanine (MC). Transmission electron microscopy, atomic force microscopy, UV/vis spectroscopy, and dynamic light scattering demonstrated the successful assembly and disassembly of SP-hb-PG micelles. In addition, the critical micelle concentration (CMC) was determined through the fluorescence analysis of pyrene to confirm the amphiphilicity of respective SP-hb-PGn (n = 15, 29, and 36) micelles, with CMC values ranging from 13 to 20 mg/L, which is correlated to the length of the polar polyglycerol backbone. Moreover, the superior biocompatibility of the prepared SP-hb-PG was evaluated using WI-38 cells and HeLa cells, suggesting the prospective applicability of the micelles in smart drug delivery systems.
Self-assembly of nanosize coordination cages on si(100) surfaces.

PubMed

Busi, Marco; Laurenti, Marco; Condorelli, Guglielmo G; Motta, Alessandro; Favazza, Maria; Fragalà, Ignazio L; Montalti, Marco; Prodi, Luca; Dalcanale, Enrico

2007-01-01

Bottom-up fabrication of 3D organic nanostructures on Si(100) surfaces has been achieved by a two-step procedure. Tetradentate cavitand 1 was grafted on the Si surface together with 1-octene (Oct) as a spatial spectator by photochemical hydrosilylation. Ligand exchange between grafted cavitand 1 and self-assembled homocage 2, derived from cavitand 5 bearing a fluorescence marker, led to the formation of coordination cages on Si(100). Formation, quantification, and distribution of the nanoscale molecular containers on a silicon surface was assessed by using three complementary analytical techniques (AFM, XPS, and fluorescence) and validated by control experiments on cavitand-free silicon surfaces. Interestingly, the fluorescence of pyrene at approximately 4 nm above the Si(100) surface can be clearly observed.
Garry Rumbles | NREL

Science.gov Websites

, colloidal quantum dots, and single-walled carbon nanotubes. Laser-based experiments (time-resolved fluorescence spectroscopy; time-resolved resonance Raman spectroscopy; laser-induced fluorescence spectroscopy ; time-resolved evanescent wave-induced fluorescence spectroscopy; picosecond coherent anti-Stokes Raman
Ligation-rolling circle amplification combined with γ-cyclodextrin mediated stemless molecular beacon for sensitive and specific genotyping of single-nucleotide polymorphism.

PubMed

Zou, Zhen; Qing, Zhihe; He, Xiaoxiao; Wang, Kemin; He, Dinggeng; Shi, Hui; Yang, Xue; Qing, Taiping; Yang, Xiaoxiao

2014-07-01

A novel approach for highly sensitive and selective genotyping of single-nucleotide polymorphism (SNP) has been developed based on ligation-rolling circle amplification (L-RCA) and stemless molecular beacon. In this approach, two tailored DNA probes were involved. The stemless molecular beacon, formed through the inclusion interactions of γ-cyclodextrin (γ-CD) and bis-pyrene labeled DNA fragment, was served as signal probe. In the absence of mutant target, the two pyrene molecules were bound in the γ-CD cavity to form an excimer and showed a strong fluorescence at 475 nm. It was here named γ-CD-P-MB. The padlock DNA probe was designed as recognition probe. Upon the recognition of a point mutation DNA targets, the padlock probe was ligated to generate a circular template. An RCA amplification was then initiated using the circular template in the presence of Phi29 polymerase and dNTPs. The L-RCA products, containing repetitive sequence units, subsequently hybridized with the γ-CD-P-MB. This made pyrene molecules away from γ-CD cavity and caused a decrease of excimer fluorescence. As a proof-of-concept, SNP typing of β-thalassemia gene at position -28 was investigated using this approach. The detection limit of mutated target was determined to be 40 fM. In addition, DNA ligase offered high fidelity in distinguishing the mismatched bases at the ligation site, resulting in positive detection of mutant target even when the ratio of the wildtype to the mutant is 999:1. Given these attractive characteristics, the developed approach might provide a great genotyping platform for pathogenic diagnosis and genetic analysis. Copyright © 2014 Elsevier B.V. All rights reserved.
An ultrafast spectroscopic and quantum mechanical investigation of multiple emissions in push-pull pyridinium derivatives bearing different electron donors.

PubMed

Carlotti, B; Benassi, E; Cesaretti, A; Fortuna, C G; Spalletti, A; Barone, V; Elisei, F

2015-08-28

A joint experimental and theoretical approach, involving state-of-the-art femtosecond fluorescence up-conversion measurements and quantum mechanical computations including vibronic effects, was employed to get a deep insight into the excited state dynamics of two cationic dipolar chromophores (Donor-π-Acceptor(+)) where the electron deficient portion is a N-methyl pyridinium and the electron donor a trimethoxyphenyl or a pyrene, respectively. The ultrafast spectroscopic investigation, and the time resolved area normalised emission spectra in particular, revealed a peculiar multiple emissive behaviour and allowed the distinct emitting states to be remarkably distinguished from solvation dynamics, occurring in water in a similar timescale. The two and three emissions experimentally detected for the trimethoxyphenyl and pyrene derivatives, respectively, were associated with specific local emissive minima in the potential energy surface of S1 on the ground of quantum-mechanical calculations. A low polar and planar Locally Excited (LE) state together with a highly polar and Twisted Intramolecular Charge Transfer (TICT) state is identified to be responsible for the dual emission of the trimethoxyphenyl compound. Interestingly, the more complex photobehaviour of the pyrenyl derivative was explained considering the contribution to the fluorescence coming not only from the LE and TICT states but also from a nearly Planar Intramolecular Charge Transfer (PICT) state, with both the TICT and the PICT generated from LE by progressive torsion around the quasi-single bond between the methylpyridinium and the ethene bridge. These findings point to an interconversion between rotamers for the pyrene compound taking place in its excited state against the Non-equilibrated Excited Rotamers (NEER) principle.
Separation and characterization of gall bladder bile metabolites from speckled trout, Salvelinus fontinalis, exposed to individual polycyclic aromatic compounds.

PubMed

Leonard, J D; Hellou, J

2001-03-01

Speckled trout, Salvelinus fontinalis, were orally exposed to individual polycyclic aromatic compounds (PACs) represented by benzo[a]pyrene, carbazole, chrysene, dibenzofuran, dibenzothiophene, fluorene, phenanthrene, and pyrene. Fish were sacrificed 7 d after exposure and the gall bladder removed for bile analysis. High pressure liquid chromatography (HPLC) with fluorescence (F) and ultraviolet (UV) detection was used to determine the presence of PAC derivatives in the bile without pretreatment. Glucuronide conjugates were predominant in all exposures with variable amounts (0-53%) of phenols and starting material. Identification of compounds was confirmed by selective extraction of less polar nonconjugated PACs and enzymatic hydrolysis of water-soluble material. This was followed by HPLC and/or gas chromatography-mass spectrometry (GCMS) characterization of the produced phenols. Total metabolite levels varied widely among compounds.
Complexation between sodium dodecyl sulfate and amphoteric polyurethane nanoparticles.

PubMed

Qiao, Yong; Zhang, Shifeng; Lin, Ouya; Deng, Liandong; Dong, Anjie

2007-09-27

The complexation between negatively charged sodium dodecyl sulfate (SDS) and positively charged amphoteric polyurethane (APU) self-assembled nanoparticles (NPs) containing nonionic hydrophobic segments is studied by dynamic light scattering, pyrene fluorescent probing, zeta-potential, and transmission electron microscopy (TEM) in the present paper. With increasing the mol ratio of SDS to the positive charges on the surface of APU NPs, the aqueous solution of APU NPs presents precipitation at pH 2, around stoichiometric SDS concentration, and then the precipitate dissociates with excess SDS to form more stable nanoparticles of ionomer complexes. Three stages of the complexation process are clearly shown by the pyrene I1/I3 variation of the complex systems, which only depends on the ratio of SDS/APU, and demonstrate that the process is dominated by electrostatic attraction and hydrophobic aggregation.
Multinuclear Phthalocyanine-Fused Molecular Nanoarrays: Synthesis, Spectroscopy, and Semiconducting Property.

PubMed

Shang, Hong; Xue, Zheng; Wang, Kang; Liu, Huibiao; Jiang, Jianzhuang

2017-06-27

The post-cyclization strategy rather than the conventional ante-cyclotetramerization method was employed for the synthesis of multinuclear phthalocyanine-fused molecular nanoarrays. Reaction of 2,3,9,10,16,17-hexakis(2,6-dimethylphenoxy)-23,24-diaminophthalocyaninato zinc(II) with 2,7-di-tert-butylpyrene-4,5-dione, 2,7-di-tert-butylpyrene-4,5,9,10-tetraone, and hexaketocyclohexane in refluxing acetic acid afforded the corresponding mono-, bi-, and trinuclear phthalocyanine-fused zinc complexes (Pz-pyrene){Zn[Pc(OC 8 H 9 ) 6 ]} (1), (Pz 2 -pyrene){Zn[Pc(OC 8 H 9 ) 6 ]} 2 (2), {(HAT){Zn[Pc(OC 8 H 9 ) 6 ]} 3 } (3) in 46, 13, and 25 % yield, respectively, which extend the scope of multinuclear phthalocyanine-fused nanoarrays with different molecular skeletons. The self-assembly behavior of trinuclear phthalocyanine 3 in THF/CH 3 CN was investigated by electronic absorption spectroscopy and SEM, and the fabricated nanorods showed interesting semiconducting properties, which suggest good application potential of these multinuclear phthalocyanine-fused molecular nanoarrays. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Fluorescence of tautomeric forms of curcumin in different pH and biosurfactant rhamnolipids systems: Application towards on-off ratiometric fluorescence temperature sensing.

PubMed

Moussa, Zeinab; Chebl, Mazhar; Patra, Digambara

2017-08-01

Medicinal properties of curcumin are widely getting realized. For its applicability as a hydrophobic drug molecule and food spice interaction of curcumin with rhamnolipids, a biosurfactant, bears importance. Here we have explored interaction of curcumin with rhamnolipids biosurfactant and its aggregation behavior. The impact of pH on critical micelle concentration (cmc) of rhamnolipids has been studied using fluorescence of curcumin and found that cmc of rhamnolipids increases with increase in pH of the medium. In acidic, neutral and slightly alkaline medium (pH8), at λ ex =355nm (for β-diketone form) curcumin undergoes excited state hydrogen transfer (ESHT) and emits solely from enol form both in the presence and absence of rhamnolipids, but first time we report that in extreme alkaline condition, at pH13, at λ ex =355nm curcumin emits from both β-diketone as well as enolic ESHT forms in absence of rhamnolipids but in the presence of rhamnolipids β-diketone is stabilized and the emission solely comes from β-diketone by completely revoking ESHT process. Fluorescence quenching by hydrophobic cetylpyridinium bromide confirms curcumin penetrates deep inside the hydrophobic pocket of rhamnolipid aggregates/micelle by reducing the distance between N + -atom of pyridinium ion and curcumin. On the other hand hydrophobic molecule like pyrene stays near to the Stern layer of rhamnolipids facilitating electron transfer from pyrene to N + -atom of pyridinium ion. Even in neutral condition, in the presence of rhamnolipids the β-diketone form, though in small proportions, can be stabilized in higher temperature in expense of enolic ESHT form, thus, offering an on off ratiometric fluorescence temperature sensing in solution, which bears significance as ratiometric probe molecules. Interaction of curcumin with rhamnolipids stabilizes curcumin in acidic, neutral and moderate alkaline condition but fails at extreme pH13. Copyright © 2017 Elsevier B.V. All rights reserved.
Spirolactone and spirothiolactone rhodamine-pyrene probes for detection of Hg²⁺ with different sensing properties and its application in living cells.

PubMed

Rui, Qing-Qing; Zhou, Yi; Fang, Yuan; Yao, Cheng

2016-04-15

Two new rhodamine B-based fluorescent probes PyRbS and PyRbO containing pyrene moiety were designed and synthesized. Both of the probes showed colorimetric and fluorometric sensing abilities for Hg(2+) with high selectivity over other metal ions. The binding analysis using Job's plot suggested 1:1 stoichiometry for the complexes formed for Hg(2+). Compared with PyRbO, the PyRbS showed higher selectivity and sensitivity due to the thiophilic property of Hg(2+) ion. The PyRbS exhibited the linear fluorescence quenching to Hg(2+) in the range of 0.3 to 4.8 μM (λ(ex)=365 nm) and 0.3 to 5.4 μM (λ(ex)=515 nm), and the detection limit was 0.72 μM. Moreover, ratiometric changes of PyRbS with Hg(2+) in absorption spectrum were observed, which could not be obtained in the combination of PyRbO with Hg(2+). In addition, the methyl thiazolyl tetrazolium (MTT) assay demonstrated that RbPyS had low cytotoxicity and was successfully used to monitor intracellular Hg(2+) levels in living cells. Copyright © 2016 Elsevier B.V. All rights reserved.
Development and certification of a coal fly ash certified reference material for selected polycyclic aromatic hydrocarbons.

PubMed

Cao, X; Xu, X; Cui, W; Xi, Z

2001-08-01

The development and certification of a coal fly ash certified reference material (CRM) for polycyclic aromatic hydrocarbons (PAH) is described; this is the first natural matrix CRM for organic environmental analysis in China. The homogeneity and stability of this material have been tested by HPLC. The concentrations of several PAH were determined by use of two independent, different methods--solvent extraction-HPLC analysis with UV detection coupled with fluorescence detection (FLD) and solvent extraction, isolation with a silica column, and GC analysis with flame ionization detection (FID). Five certified values were determined: phenanthrene 7.1 +/- 2.6 microg g(-1), anthracene 2.0 +/- 0.8 microg g(-1), fluoranthene 7.4 +/- 1.9 microg g(-1), pyrene 7 +/- 2 microg g(-1), and benzo[a]pyrene 1.3 +/- 0.3 microg g(-1). Reference values for several other PAH are also suggested.

Mixed non-covalent assemblies of ethynyl nile red and ethynyl pyrene along oligonucleotide templates.

PubMed

Ensslen, Philipp; Fritz, Yannic; Wagenknecht, Hans-Achim

2015-01-14

Ethynyl pyrene and ethynyl nile red as modifications at the 5-position of 2'-deoxyuridines self-assemble non-covalently and specifically along oligo-2'-deoxyadenosines as templates. Oligo-2'-deoxyadenosines of the lengths (dA)10-(dA)20 are able to retain nearly exactly as many ethynyl nile red units in solution as binding sites are available on these templates. In contrast, in the presence of oligo-2'-thymidines the ethynyl nile red moieties are similarly insoluble to those in the absence of any oligonucleotide and yield an aggregate. The mixed assemblies of both chromophores are highly ordered, show left-handed chirality and yield dual fluorescence. The strong excitonic coupling indicates assemblies with a high degree of order. These results show that DNA represents an important supramolecular scaffold for the templated, helical and non-covalent arrangement not only for one type of chromophore but also for mixtures of two different chromophores.
Rapid communication: effects of tobacco processing on the quantity of benzo[a]pyrene in mainstream smoke.

PubMed

Martin, Lin Alicia; Byrd, Sherell K; Milofsky, Robert E

2003-07-25

Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon produced during incomplete combustion of organic compounds and is one of the more carcinogenic PAHs detected in tobacco smoke. Addition of organic compounds during tobacco processing increases the likelihood of finding elevated concentrations of BaP in mainstream smoke when compared to smoke from unprocessed tobacco. To test this hypothesis, the tobacco from Marlboro "Red" (processed) cigarettes and nonprocessed Burley tobacco leaf cigarettes was combusted and the resulting combustion products were collected onto glass fiber filter pads. The quantity of BaP in the tobacco tar extracted from the pads was measured using reversed-phase liquid chromatography with fluorescence detection. The concentration of BaP in the processed tobacco smoke was significantly higher than in unprocessed tobacco smoke. These results suggest that compounds added during tobacco processing increase the concentrations of BaP and therefore the carcinogenic potential of cigarettes.
Polynuclear aromatic hydrocarbon analysis using the synchronous scanning luminoscope

NASA Astrophysics Data System (ADS)

Hyfantis, George J., Jr.; Teglas, Matthew S.; Wilbourn, Robert G.

2001-02-01

12 The Synchronous Scanning Luminoscope (SSL) is a field- portable, synchronous luminescence spectrofluorometer that was developed for on-site analysis of contaminated soil and ground water. The SSL is capable of quantitative analysis of total polynuclear aromatic hydrocarbons (PAHs) using phosphorescence and fluorescence techniques with a high correlation to laboratory data as illustrated by this study. The SSL is also capable of generating benzo(a)pyrene equivalency results, based on seven carcinogenic PAHs and Navy risk numbers, with a high correlation to laboratory data as illustrated by this study. These techniques allow rapid field assessments of total PAHs and benzo(a)pyrene equivalent concentrations. The Luminoscope is capable of detecting total PAHs to the parts per billion range. This paper describes standard field methods for using the SSL and describes the results of field/laboratory testing of PAHs. SSL results from two different hazardous waste sites are discussed.
Liquid chromatographic determination of benzo(a)pyrene in total particulate matter of cigarette smoke

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomkins, B.A.; Jenkins, R.A.; Griest, W.H.

The benzo(a)pyrene (BaP) delivery of reference and commercially available tobacco cigarettes, as well as reference and placebo marijuana cigarettes, is determined using a sequential liquid chromatographic/liquid chromatographic procedure. The total particulate matter of sample cigarette smoke is collected using a Cambridge filter pad, which is ultrasonically extracted with acetone. The resulting extract is filtered, then fractionated using semipreparative-scale normal phase liquid chromatography (LC). Quantitative determination is achieved using analytical-scale reverse phase LC equipped with a fluorescence detector. The method is precise (+/- 10-15% relative standard deviation) and yields 85% or better BaP recovery at the ng/cig. level. A single padmore » may be analyzed in 8 person-hours, while a more typical lot of 12 pads (6 pads each for 2 cigarette brands) may be analyzed in 10 person-days.« less
Detecting Kerogen as a Biosignature Using Colocated UV Time-Gated Raman and Fluorescence Spectroscopy.

PubMed

Shkolyar, Svetlana; Eshelman, Evan J; Farmer, Jack D; Hamilton, David; Daly, Michael G; Youngbull, Cody

2018-04-01

The Mars 2020 mission will analyze samples in situ and identify any that could have preserved biosignatures in ancient habitable environments for later return to Earth. Highest priority targeted samples include aqueously formed sedimentary lithologies. On Earth, such lithologies can contain fossil biosignatures as aromatic carbon (kerogen). In this study, we analyzed nonextracted kerogen in a diverse suite of natural, complex samples using colocated UV excitation (266 nm) time-gated (UV-TG) Raman and laser-induced fluorescence spectroscopies. We interrogated kerogen and its host matrix in samples to (1) explore the capabilities of UV-TG Raman and fluorescence spectroscopies for detecting kerogen in high-priority targets in the search for possible biosignatures on Mars; (2) assess the effectiveness of time gating and UV laser wavelength in reducing fluorescence in Raman spectra; and (3) identify sample-specific issues that could challenge rover-based identifications of kerogen using UV-TG Raman spectroscopy. We found that ungated UV Raman spectroscopy is suited to identify diagnostic kerogen Raman bands without interfering fluorescence and that UV fluorescence spectroscopy is suited to identify kerogen. These results highlight the value of combining colocated Raman and fluorescence spectroscopies, similar to those obtainable by SHERLOC on Mars 2020, to strengthen the confidence of kerogen detection as a potential biosignature in complex natural samples. Key Words: Raman spectroscopy-Laser-induced fluorescence spectroscopy-Mars Sample Return-Mars 2020 mission-Kerogen-Biosignatures. Astrobiology 18, 431-453.
A virus-MIPs fluorescent sensor based on FRET for highly sensitive detection of JEV.

PubMed

Liang, Caishuang; Wang, Huan; He, Kui; Chen, Chunyan; Chen, Xiaoming; Gong, Hang; Cai, Changqun

2016-11-01

Major stumbling blocks in the recognition and detection of virus are the unstable biological recognition element or the complex detection means. Here a fluorescent sensor based on virus-molecular imprinted polymers (virus-MIPs) was designed for specific recognition and highly sensitive detection of Japanese encephalitis virus (JEV). The virus-MIPs were anchored on the surface of silica microspheres modified by fluorescent dye, pyrene-1-carboxaldehyde (PC). The fluorescence intensity of PC can be enhanced by the principle of fluorescence resonance energy transfer (FRET), where virus acted as energy donor and PC acted as energy acceptor. The enhanced fluorescence intensity was proportional to the concentration of virus in the range of 24-960pM, with a limit of detection (LOD, 3σ) of 9.6pM, and the relative standard deviation was 1.99%. In additional, the specificity study confirmed the resultant MIPs has high-selectivity for JEV. This sensor would become a new key for the detection of virus because of its high sensitive, simple operation, high stability and low cost. Copyright © 2016. Published by Elsevier B.V.
Toxicity and photoactivation of PAH mixtures in marine sediment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swartz, R.; Ferraro, S.; Lamberson, J.

1995-12-31

The toxicity and toxicological photoactivation of mixtures of sediment-associated fluoranthene, phenanthrene, pyrene, and acenaphthene were determined using standard 10 d sediment toxicity tests with the marine amphipod, Rhepoxynius abronius. The four PAHs were spiked into sediment in a concentration series of either single compounds or an equitoxic mixture. Spiked sediment was stored at 4 C for 28 d before testing. Toxicity tests were conducted under fluorescent lighting. Survivors after 10 d in PAH-contaminated sediment were exposed for 1 h to UV light in the absence of sediment and then tested for their ability to bury in clean sediment. The 10more » d LC50s for single PAHs were 3.3, 2.2, 2.8, and 2.3 mg/g oc for fluoranthene, phenanthrene, pyrene, and acenaphthene, respectively. These LC50s were used to calculate the sum of toxic units ({Sigma}TU) of the four PAHs in the equitoxic mixture treatments. The {Sigma}TU LC50 was then calculated for the mixture treatments. If the toxicological interaction of the four PAHs in the mixture was additive, the {Sigma}TU LC50 should equal 1.0. The observed {Sigma}TU LC50 in the mixture was 1.55, indicating the interaction was slightly less than additive. UV enhancement of toxic effects of individual PAHs was correctly predicted by photophysical properties, i.e. pyrene and fluoranthene were photoactivated and phenanthrene and acenaphthene were not. UV effects in the mixture of four PAHs can be explained by the photoactivation of pyrene and fluoranthene alone.« less
Fluorescence spectroscopy for the detection of potentially malignant disorders of the oral cavity: analysis of 30 cases

NASA Astrophysics Data System (ADS)

Francisco, A. L. N.; Correr, W. R.; Azevedo, L. H.; Galletta, V. K.; Pinto, C. A. L.; Kowalski, L. P.; Kurachi, C.

2014-01-01

Oral cancer is a major health problem worldwide and although early diagnosis of potentially malignant and malignant diseases is associated with better treatment results, a large number of cancers are initially misdiagnosed, with unfortunate consequences for long-term survival. Fluorescence spectroscopy is a noninvasive modality of diagnostic approach using induced fluorescence emission in tumors that can improve diagnostic accuracy. The objective of this study was to determine the ability to discriminate between normal oral mucosa and potentially malignant disorders by fluorescence spectroscopy. Fluorescence investigation under 408 and 532 nm excitation wavelengths was performed on 60 subjects, 30 with potentially malignant disorders and 30 volunteers with normal mucosa. Data was analyzed to correlate fluorescence patterns with clinical and histopathological diagnostics. Fluorescence spectroscopy used as a point measurement technique resulted in a great variety of spectral information. In a qualitative analysis of the fluorescence spectral characteristics of each type of injury evaluated, it was possible to discriminate between normal and abnormal oral mucosa. The results show the potential use of fluorescence spectroscopy for an improved discrimination of oral disorders.
Fluorescence spectroscopy for diagnosis of squamous intraepithelial lesions of the cervix.

PubMed

Mitchell, M F; Cantor, S B; Ramanujam, N; Tortolero-Luna, G; Richards-Kortum, R

1999-03-01

To calculate receiver operating characteristic (ROC) curves for fluorescence spectroscopy in order to measure its performance in the diagnosis of squamous intraepithelial lesions (SILs) and to compare these curves with those for other diagnostic methods: colposcopy, cervicography, speculoscopy, Papanicolaou smear screening, and human papillomavirus (HPV) testing. Data from our previous clinical study were used to calculate ROC curves for fluorescence spectroscopy. Curves for other techniques were calculated from other investigators' reports. To identify these, a MEDLINE search for articles published from 1966 to 1996 was carried out, using the search terms "colposcopy," "cervicoscopy," "cervicography," "speculoscopy," "Papanicolaou smear," "HPV testing," "fluorescence spectroscopy," and "polar probe" in conjunction with the terms "diagnosis," "positive predictive value," "negative predictive value," and "receiver operating characteristic curve." We found 270 articles, from which articles were selected if they reported results of studies involving high-disease-prevalence populations, reported findings of studies in which colposcopically directed biopsy was the criterion standard, and included sufficient data for recalculation of the reported sensitivities and specificities. We calculated ROC curves for fluorescence spectroscopy using Bayesian and neural net algorithms. A meta-analytic approach was used to calculate ROC curves for the other techniques. Areas under the curves were calculated. Fluorescence spectroscopy using the neural net algorithm had the highest area under the ROC curve, followed by fluorescence spectroscopy using the Bayesian algorithm, followed by colposcopy, the standard diagnostic technique. Cervicography, Papanicolaou smear screening, and HPV testing performed comparably with each other but not as well as fluorescence spectroscopy and colposcopy. Fluorescence spectroscopy performs better than colposcopy and other techniques in the diagnosis of SILs. Because it also permits real-time diagnosis and has the potential of being used by inexperienced health care personnel, this technology holds bright promise.
Detection of benzo[a]pyrene diol epoxide-DNA adducts in peripheral blood lymphocytes and antibodies to the adducts in serum from coke oven workers.

PubMed Central

Harris, C C; Vahakangas, K; Newman, M J; Trivers, G E; Shamsuddin, A; Sinopoli, N; Mann, D L; Wright, W E

1985-01-01

Coke oven workers are exposed to high levels of carcinogenic polycyclic aromatic hydrocarbons, including benzo[a]pyrene (B[a]P), and are at increased risk of lung cancer. Since B[a]P is enzymatically activated to 7 beta,8 alpha-dihydroxy(9 alpha, 10 alpha)epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (B[a]PDE) that forms adducts with DNA, the presence of these adducts was measured in DNA from peripheral blood lymphocytes by synchronous fluorescence spectrophotometry and enzyme radioimmunoassay. Approximately two-thirds of the workers had detectable levels of B[a]PDE-DNA adducts. Antibodies to the DNA adducts were also found in the serum of 27% of the workers. B[a]PDE-DNA adducts were not detectable in lymphocytes and antibodies to the adducts were not detected in sera from a control group of nonsmoking laboratory workers. DNA adducts and/or antibodies to the adducts indicate exposure to B[a]P and its metabolic activation to the carcinogenic metabolite that covalently binds to and damages DNA. Detection of adducts and antibodies to them may also be useful as internal dosimeters of the pathobiological effective doses of chemical carcinogens. PMID:2413443
Ambient air levels and health risk assessment of benzo(a)pyrene in atmospheric particulate matter samples from low-polluted areas: application of an optimized microwave extraction and HPLC-FL methodology.

PubMed

de la Gala Morales, María; Holgado, Fernando Rueda; Marín, Ma Rosario Palomo; Blázquez, Lorenzo Calvo; Gil, Eduardo Pinilla

2015-04-01

A new methodology involving a simple and fast pretreatment of the samples by microwave-assisted extraction and concentration by N2 stream, followed by HPLC with fluorescence detection, was used for determining the concentration of benzo(a)pyrene (BaP) in atmospheric particulate matter (PM10 fraction). Obtained LOD, 1.0 × 10(-3) ng/m(3), was adequate for the analysis of benzo(a)pyrene in the samples, and BaP recovery from PAH in Fine Dust (PM10-like) certified reference material was nearly quantitative (86%). The validated procedure was applied for analyzing 115 PM10 samples collected at different sampling locations in the low-polluted area of Extremadura (Southwest Spain) during a monitoring campaign carried out in 2011-2012. BaP spatial variations and seasonal variability were investigated as well as the influence of meteorological conditions and different air pollutants concentrations. A normalized protocol for health risk assessment was applied to estimate lifetime cancer risk due to BaP inhalation in the sampling areas, finding that around eight inhabitants per million people may develop lung cancer due to the exposition to BaP in atmospheric particulates emitted by the investigated sources.
Three-dimensional representations of photo-induced electron transfer rates in pyrene-(CH2)n-N,N'-dimethylaniline systems obtained by three electron transfer theories.

PubMed

Rujkorakarn, Rong; Tanaka, Fumio

2009-01-01

The observed rates of photo-induced electron transfer (ET) from N,N'-dimethylaniline (DMA) to the excited pyrene (Py) in confined systems of pyrene-(CH(2))(n)-N,N'- dimethylaniline (PnD: n=1-3) were studied by molecular dynamic simulation (MD) and three kinds of electron transfer theories. ET parameters contained in Marcus theory (M theory), Bixon and Jortner theory (BJ theory) and Kakitani and Mataga theory (KM theory) were determined so as to fit the calculated fluorescence intensities with those obtained by the observed ET rates, according to a non-linear least squares method. Three-dimensional profiles of logarithm of calculated ET rates depending on two of three ET parameters, R, epsilon(0) and -DeltaG degrees were systematically examined with best-fit ET parameters of P1D. Bell shape dependencies of ET rate were predicted on R and on epsilon(0), and on -DeltaG degrees as well, by M theory and KM theory. The profiles of logarithm of ET rate calculated by BJ theory exhibited oscillatory dependencies not only on -DeltaG degrees , but also on R and on epsilon(0). Relationship between ET state and charge transfer complex was discussed with BJ theory.
Excimer-based peptide beacons: a convenient experimental approach for monitoring polypeptide-protein and polypeptide-oligonucleotide interactions.

PubMed

Oh, Kenneth J; Cash, Kevin J; Plaxco, Kevin W

2006-11-01

While protein-polypeptide and nucleic acid-polypeptide interactions are of significant experimental interest, quantitative methods for the characterization of such interactions are often cumbersome. Here we described a relatively simple means of optically monitoring such interactions using excimer-based peptide beacons (PBs). The design of PBs is based on the observation that, whereas short peptides are almost invariably unfolded and highly dynamic, they become rigid when complexed with macromolecular targets. Using this binding-induced folding to segregate two pyrene moieties and therefore inhibit excimer formation, we have produced PBs directed against both anti-HIV antibodies and the retroviral transactive response (TAR) RNA hairpin. For both polypeptides, target recognition is accompanied by a roughly 2-fold decrease in excimer emission, thus allowing the detection of their respective targets at concentrations of a few nanomolar. Because excimer emission requires the formation of a tight, precisely oriented pyrene dimer, even relatively trivial binding-induced segregation reduces fluorescence significantly. This suggests that the PB approach will be suitable for monitoring a wide range of peptide-macromolecule recognition events. Moreover, the synthesis of excimer-based PBs utilizes commercially available modified pyrenes in a simple and well-established protocol, making the approach well suited for routine laboratory applications.
Effects of humic substances on the bioconcentration of polycyclic aromatic hydrocarbons: Correlations with spectroscopic and chemical properties of humic substances

USGS Publications Warehouse

Haitzer, M.; Abbt-Braun, G.; Traunspurger, W.; Steinberg, C.E.W.

1999-01-01

The presence of dissolved humic substances (HS, fulvic and humic acids) generally reduces the uptake of hydrophobic organic compounds into aquatic organisms. The extent of this effect depends both on the concentration and on the origin of the HS. The aim of this study was to investigate the role of qualitative differences between HS from different origins. The effects of seven different HS on the bioconcentration of pyrene and benzo[a]pyrene (BaP) in the nematode Caenorhabditis elegans were related to the spectroscopic and chemical properties of the HS. The effect of each humic material on the bioconcentration of pyrene or BaP was quantified as a 'biologically determined' partition coefficient K(DOC). We observed significant linear relationships between K(DOC) and the atomic H/C ratio, the specific absorptivity at 254 nm, the content of aromatic carbons (as determined by 13C nuclear magnetic resonance spectroscopy, the copper-complexing capacity, the content of phenolic OH groups, and the molecular weight of the HS. There was no discernible relationship of K(DOC) with the atomic (N + O)/C ratio, an indicator of the polarity of HS. Taken together, our results show that the variability in the effects of HS from different origins could be related to variations in bulk properties of the HS. Parameters describing the aromaticity of the humic materials seemed to be most useful for estimating effects of HS on the bioconcentration of pyrene and BaP.
Structure and self-assembly properties of a new chitosan-based amphiphile.

PubMed

Huang, Yuping; Yu, Hailong; Guo, Liang; Huang, Qingrong

2010-06-17

A new chitosan-based amphiphile, octanoyl-chitosan-polyethylene glycol monomethyl ether (acylChitoMPEG), has been prepared using both hydrophobic octanoyl and hydrophilic polyethylene glycol monomethyl ether (MPEG) substitutions. The success of synthesis was confirmed by Fourier transform infrared (FT-IR) and (1)H NMR spectroscopy. The synthesized acylChitoMPEG exhibited good solubility in either aqueous solution or common organic solvents such as ethanol, acetone, and CHCl(3). The self-aggregation behavior of acylChitoMPEG in solutions was studied by a combination of pyrene fluorescence technique, dynamic light scattering, atomic force microscopy, and small-angle X-ray scattering (SAXS). The critical aggregation concentration (CAC) and hydrodynamic diameter were found to be 0.066 mg/mL and 24.4 nm, respectively. SAXS results suggested a coiled structure of the triple helical acylChitoMPEG backbone with the hydrophobic moieties hiding in the center of the backbone, and the hydrophilic MPEG chains surrounding the acylChitoMPEG backbone in a random Gaussian chain conformation. Cytotoxicity results showed that acylChitoMPEG exhibited negligible cytotoxicity even at concentrations as high as 1.0 mg/mL. All results implied that acylChitoMPEG has the potential to be used for biological or medical applications.
Fluorescent probes for nucleic Acid visualization in fixed and live cells.

PubMed

Boutorine, Alexandre S; Novopashina, Darya S; Krasheninina, Olga A; Nozeret, Karine; Venyaminova, Alya G

2013-12-11

This review analyses the literature concerning non-fluorescent and fluorescent probes for nucleic acid imaging in fixed and living cells from the point of view of their suitability for imaging intracellular native RNA and DNA. Attention is mainly paid to fluorescent probes for fluorescence microscopy imaging. Requirements for the target-binding part and the fluorophore making up the probe are formulated. In the case of native double-stranded DNA, structure-specific and sequence-specific probes are discussed. Among the latest, three classes of dsDNA-targeting molecules are described: (i) sequence-specific peptides and proteins; (ii) triplex-forming oligonucleotides and (iii) polyamide oligo(N-methylpyrrole/N-methylimidazole) minor groove binders. Polyamides seem to be the most promising targeting agents for fluorescent probe design, however, some technical problems remain to be solved, such as the relatively low sequence specificity and the high background fluorescence inside the cells. Several examples of fluorescent probe applications for DNA imaging in fixed and living cells are cited. In the case of intracellular RNA, only modified oligonucleotides can provide such sequence-specific imaging. Several approaches for designing fluorescent probes are considered: linear fluorescent probes based on modified oligonucleotide analogs, molecular beacons, binary fluorescent probes and template-directed reactions with fluorescence probe formation, FRET donor-acceptor pairs, pyrene excimers, aptamers and others. The suitability of all these methods for living cell applications is discussed.
In vivo native fluorescence spectroscopy and nicotinamide adinine dinucleotide/flavin adenine dinucleotide reduction and oxidation states of oral submucous fibrosis for chemopreventive drug monitoring

NASA Astrophysics Data System (ADS)

Sivabalan, Shanmugam; Vedeswari, C. Ponranjini; Jayachandran, Sadaksharam; Koteeswaran, Dornadula; Pravda, Chidambaranathan; Aruna, Prakasa Rao; Ganesan, Singaravelu

2010-01-01

Native fluorescence spectroscopy has shown potential to characterize and diagnose oral malignancy. We aim at extending the native fluorescence spectroscopy technique to characterize normal and oral submucous fibrosis (OSF) patients under pre- and post-treated conditions, and verify whether this method could also be considered in the monitoring of therapeutic prognosis noninvasively. In this study, 28 normal subjects and 28 clinically proven cases of OSF in the age group of 20 to 40 years are diagnosed using native fluorescence spectroscopy. The OSF patients are given dexamethasone sodium phosphate and hyaluronidase twice a week for 6 weeks, and the therapeutic response is monitored using fluorescence spectroscopy. The fluorescence emission spectra of normal and OSF cases of both pre- and post-treated conditions are recorded in the wavelength region of 350 to 600 nm at an excitation wavelength of 330 nm. The statistical significance is verified using discriminant analysis. The oxidation-reduction ratio of the tissue is also calculated using the fluorescence emission intensities of flavin adenine dinucleotide and nicotinamide adinine dinucleotide at 530 and 440 nm, respectively, and they are compared with conventional physical clinical examinations. This study suggests that native fluorescence spectroscopy could also be extended to OSF diagnosis and therapeutic prognosis.
Dual time-resolved temperature-jump fluorescence and infrared spectroscopy for the study of fast protein dynamics.

PubMed

Davis, Caitlin M; Reddish, Michael J; Dyer, R Brian

2017-05-05

Time-resolved temperature-jump (T-jump) coupled with fluorescence and infrared (IR) spectroscopy is a powerful technique for monitoring protein dynamics. Although IR spectroscopy of the polypeptide amide I mode is more technically challenging, it offers complementary information because it directly probes changes in the protein backbone, whereas, fluorescence spectroscopy is sensitive to the environment of specific side chains. With the advent of widely tunable quantum cascade lasers (QCL) it is possible to efficiently probe multiple IR frequencies with high sensitivity and reproducibility. Here we describe a dual time-resolved T-jump fluorescence and IR spectrometer and its application to study protein folding dynamics. A Q-switched Ho:YAG laser provides the T-jump source for both time-resolved IR and fluorescence spectroscopy, which are probed by a QCL and Ti:Sapphire laser, respectively. The Ho:YAG laser simultaneously pumps the time-resolved IR and fluorescence spectrometers. The instrument has high sensitivity, with an IR absorbance detection limit of <0.2mOD and a fluorescence sensitivity of 2% of the overall fluorescence intensity. Using a computer controlled QCL to rapidly tune the IR frequency it is possible to create a T-jump induced difference spectrum from 50ns to 0.5ms. This study demonstrates the power of the dual time-resolved T-jump fluorescence and IR spectroscopy to resolve complex folding mechanisms by complementary IR absorbance and fluorescence measurements of protein dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.
Dual time-resolved temperature-jump fluorescence and infrared spectroscopy for the study of fast protein dynamics

NASA Astrophysics Data System (ADS)

Davis, Caitlin M.; Reddish, Michael J.; Dyer, R. Brian

2017-05-01

Time-resolved temperature-jump (T-jump) coupled with fluorescence and infrared (IR) spectroscopy is a powerful technique for monitoring protein dynamics. Although IR spectroscopy of the polypeptide amide I mode is more technically challenging, it offers complementary information because it directly probes changes in the protein backbone, whereas, fluorescence spectroscopy is sensitive to the environment of specific side chains. With the advent of widely tunable quantum cascade lasers (QCL) it is possible to efficiently probe multiple IR frequencies with high sensitivity and reproducibility. Here we describe a dual time-resolved T-jump fluorescence and IR spectrometer and its application to study protein folding dynamics. A Q-switched Ho:YAG laser provides the T-jump source for both time-resolved IR and fluorescence spectroscopy, which are probed by a QCL and Ti:Sapphire laser, respectively. The Ho:YAG laser simultaneously pumps the time-resolved IR and fluorescence spectrometers. The instrument has high sensitivity, with an IR absorbance detection limit of < 0.2 mOD and a fluorescence sensitivity of 2% of the overall fluorescence intensity. Using a computer controlled QCL to rapidly tune the IR frequency it is possible to create a T-jump induced difference spectrum from 50 ns to 0.5 ms. This study demonstrates the power of the dual time-resolved T-jump fluorescence and IR spectroscopy to resolve complex folding mechanisms by complementary IR absorbance and fluorescence measurements of protein dynamics.
Intracellular applications of fluorescence correlation spectroscopy: prospects for neuroscience.

PubMed

Kim, Sally A; Schwille, Petra

2003-10-01

Based on time-averaging fluctuation analysis of small fluorescent molecular ensembles in equilibrium, fluorescence correlation spectroscopy has recently been applied to investigate processes in the intracellular milieu. The exquisite sensitivity of fluorescence correlation spectroscopy provides access to a multitude of measurement parameters (rates of diffusion, local concentration, states of aggregation and molecular interactions) in real time with fast temporal and high spatial resolution. The introduction of dual-color cross-correlation, imaging, two-photon excitation, and coincidence analysis coupled with fluorescence correlation spectroscopy has expanded the utility of the technique to encompass a wide range of promising applications in living cells that may provide unprecedented insight into understanding the molecular mechanisms of intracellular neurobiological processes.

21-Methylpyrenyl-cholesterol stably and specifically associates with lipoprotein peripheral hemi-membrane: A new labelling tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaibelet, Gérald; CEA, SB2SM and UMR8221 CNRS, IBiTec-Saclay, Gif-sur-Yvette; Tercé, François

Highlights: •21-Methylpyrenyl-cholesterol specifically and stably associates to lipoproteins. •It is not esterified by LCAT, and thus reliably labels their peripheral hemi-membrane. •HDL vs. LDL are well distinguishable by various fluorescent labelling characteristics. •LDL peripheral hemi-membrane harbors cholesterol-rich ordered lipid (micro)domains. •Cultured cells can be stained by such labelled lipoproteins-mediated delivery. -- Abstract: Lipoproteins are important biological components. However, they have few convenient fluorescent labelling probes currently reported, and their physiological reliability can be questioned. We compared the association of two fluorescent cholesterol derivatives, 22-nitrobenzoxadiazole-cholesterol (NBD-Chol) and 21-methylpyrenyl-cholesterol (Pyr-met-Chol), to serum lipoproteins and to purified HDL and LDL. Both lipoproteins couldmore » be stably labelled by Pyr-met-Chol, but virtually not by NBD-Chol. At variance with NBD-Chol, LCAT did not esterify Pyr-met-Chol. The labelling characteristics of lipoproteins by Pyr-met-Chol were well distinguishable between HDL and LDL, regarding dializability, associated probe amount and labelling kinetics. We took benefit of the pyrene labelling to approach the structural organization of LDL peripheral hemi-membrane, since Pyr-met-Chol-labelled LDL, but not HDL, presented a fluorescence emission of pyrene excimers, indicating that the probe was present in an ordered lipid micro-environment. Since the peripheral membrane of LDL contains more sphingomyelin (SM) than HDL, this excimer formation was consistent with the existence of cholesterol- and SM-enriched lipid microdomains in LDL, as already suggested in model membranes of similar composition and reminiscent to the well-described “lipid rafts” in bilayer membranes. Finally, we showed that Pyr-met-Chol could stain cultured PC-3 cells via lipoprotein-mediated delivery, with a staining pattern well different to that observed with NBD-Chol non-specifically delivered to the cells.« less
2'-Bispyrene-modified 2'-O-methyl RNA probes as useful tools for the detection of RNA: synthesis, fluorescent properties, and duplex stability.

PubMed

Krasheninina, Olga A; Novopashina, Darya S; Lomzov, Alexander A; Venyaminova, Alya G

2014-09-05

The synthesis and properties two series of new 2'-O-methyl RNA probes, each containing a single insertion of a 2'-bispyrenylmethylphosphorodiamidate derivative of a nucleotide (U, C, A, and G), are described. As demonstrated by UV melting studies, the probes form stable complexes with model RNAs and DNAs. Significant increases (up to 21-fold) in pyrene excimer fluorescence intensity were observed upon binding of most of the probes with complementary RNAs, but not with DNAs. The fluorescence spectra are independent of the nature of the modified nucleotides. The nucleotides on the 5'-side of the modified nucleotide have no effect on the fluorescence spectra, whereas the natures of the two nucleotides on the 3'-side are important: CC, CG, and UC dinucleotide units on the 3'-side of the modified nucleotide provide the maximum increases in excimer fluorescence intensity. This study suggests that these 2'-bispyrene-labeled 2'-O-methyl RNA probes might be useful tools for detection of RNAs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Conformationally Induced Off-On Cell Membrane Chemosensor Targeting Receptor Protein-Tyrosine Kinases for in Vivo and in Vitro Fluorescence Imaging of Cancers.

PubMed

Jiao, Yang; Yin, Jiqiu; He, Haiyang; Peng, Xiaojun; Gao, Qianmiao; Duan, Chunying

2018-05-09

Molecules capable of monitoring receptor protein-tyrosine kinase expression could potentially serve as useful tools for cancer diagnosis due to the overexpression of tyrosine kinases during tumor growth and metastasis. In this work, a conformationally induced "off-on" tyrosine kinase cell membrane fluorescent sensor (SP1) was designed and evaluated for the detection and imaging of receptor protein-tyrosine kinases in vivo and in vitro. SP1 consists of sunitinib and pyrene linked via hexamethylenediamine and displays quenched fluorescence as a dimer. The fluorescence of SP1 is restored in the presence of receptor protein-tyrosine kinases upon strong interaction with SP1 at the target terminal. The unique signal response mechanism enables SP1 use for fluorescence microscopy imaging of receptor protein-tyrosine kinases in the cell membranes of living cells, allowing for the rapid differentiation of cancer cells from normal cells. SP1 can be used to visualize the chick embryo chorioallantoic membrane and mouse model tumors, suggesting its possible application for early cancer diagnosis.
Presence of Polycyclic Aromatic Hydrocarbons in Rubber Packaging Materials and in Parenteral Formulations Stored in Bottles With Rubber Stoppers.

PubMed

Bohrer, Denise; Viana, Carine; Barichello, Marcia M; de Moura, Juliane F; de Carvalho, Leandro M; Nascimento, Paulo C

2017-08-01

Rubber closures are the primary packaging material for sterile preparations intended for repeated use. Important features of rubber closures are achieved after additives are added to the elastomeric material that compounds the rubber. Among these additives is carbon black. Because of its origin, carbon black may contain polycyclic aromatic hydrocarbons (PAHs). The U.S. Environmental Protection Agency has identified 16 priority PAHs on the basis of concerns that they cause or might cause cancer in animals and humans. Regulatory agencies impose carbon black purity specifications based on limits for total PAHs (0.5 mg/kg) and benzo[a]pyrene (5 μg/kg) or benzo[a]pyrene only (250 μg/kg). PAHs in rubber packaging used for pharmaceutical formulations and in parenteral products stored in containers with rubber stoppers were investigated. To this end, the method proposed by the National Institute for Occupational Safety and Health-based on high-performance liquid chromatography with ultraviolet and fluorescence detection-was adapted to determine the levels of PAHs in rubber stoppers (gray and red) and in lipid emulsions and amino acid solutions stored in bottles with rubber stoppers. The rubber materials were shown to contain 12 PAHs, in concentrations ranging from 0.25-3.31 µg/g. Only 1 of 18 samples (11 amino acid solutions and 7 lipid emulsions) was uncontaminated. The most prevalent contaminants were pyrene, benzo[a]pyrene, and fluoranthene. The total PAH concentrations in the samples ranged from 0.11-5.96 µg/mL. Components of parenteral nutrition may be contaminated with PAHs, and rubber stoppers represent a potential source of these contaminants.
Photoactivation and toxicity of mixtures of polycyclic aromatic hydrocarbon compounds in marine sediment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swartz, R.C.; Ferraro, S.P.; Lamberson, J.O.

1997-10-01

The direct toxicity and photoinduced toxicity of sediment-associated acenaphthene, phenanthrene, fluoranthene, and pyrene were determined for the marine amphipod Rhepoxynius abronius. The four polycyclic aromatic hydrocarbons (PAHs) were spiked into sediment in a concentration series of either single compounds or as approximately equitoxic mixtures of all four compounds. Standard 10-d sediment toxicity tests were conducted under fluorescent lighting. After 10 d, survivors were exposed for 1 h to ultraviolet (UV) radiation in the absence of sediment and then tested for their ability to bury in uncontaminated sediment. The 10-d median lethal concentrations (LC50s) were 2.31 mg acenaphthene/g organic carbon (OC),more » 2.22 mg phenanthrene/g OC, 3.31 mg fluoranthene/g OC, and 2.81 mg pyrene/g OC. These LC50s were used to calculate the sum of toxic units ({Sigma}TU) of the four PAHs in the approximately equitoxic mixtures. The {Sigma}TU LC50 was then calculated for the mixture treatments. If the toxicologic interaction of a mixture of contaminants is additive, {Sigma}TU LC50 = 1.0. The observed LC50 (1.55 {Sigma}TU) was slightly, but significantly, greater than unity, indicating that the interaction of PAHs in the mixture was less than additive. Exposure to UV radiation enhanced the toxic effects of fluoranthene and pyrene, but did not affect the toxicity of acenaphthene and phenanthrene. Effects of UV radiation on the toxicity of the mixture of four PAHs could be explained by the photoactivation of fluoranthene and pyrene alone. These results are consistent with predictions based on photophysical properties of PAH compounds.« less
Fluorescence spectroscopy and imaging for noninvasive diagnostics: applications to early cancer detection in the lung

NASA Astrophysics Data System (ADS)

Mycek, Mary-Ann; Urayama, Paul; Zhong, Wei; Sloboda, Roger D.; Dragnev, Konstantin H.; Dmitrovsky, Ethan

2003-10-01

Tissue fluorescence spectroscopy and imaging are being investigated as potential methods for non-invasive detection of pre-neoplastic change in the lung and other organ systems. A substantial contribution to tissue fluorescence is known to arise from endogenous cellular fluorophores. Using steady-state and time-resolved fluorescence spectroscopy and imaging, we characterized the endogenous fluorescence properties of immortalized and carcinogen-transformed human bronchial epithelial cells. Non-invasive sensing of endogenous molecular biomarkers associated with human bronchial pre-neoplasia will be discussed.
Optimization, validation and comparison of various extraction techniques for the trace determination of polycyclic aromatic hydrocarbons in sewage sludges by liquid chromatography coupled to diode-array and fluorescence detection.

PubMed

Miège, C; Dugay, J; Hennion, M C

2003-05-02

There is a need for a better characterization of sludges from wastewater treatment plants which are destined to be spread on agricultural lands. Inorganic pollutants are regularly controlled but organic pollutants have received few attention up to now. On this paper, we have been interested on the analysis of the 16 polycyclic aromatic hydrocarbons (PAHs) listed in the US Environmental Protection Agency (US EPA) priority list and more particularly of the six PAHs listed in the European community list (fluoranthene, benzo[b and k]fluoranthene, benzo[a]pyrene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene). The analysis step consists on liquid chromatography with both fluorescence and UV detections as described in the EPA Method 8310. As for the extraction step, several techniques such as supercritical fluid extraction, pressurized liquid extraction, focused microwave extraction in open vessels, Soxhlet and ultrasonic extractions are compared after optimization of the experimental conditions (solvent nature and quantity, temperature, pressure, duration, ... ) and validation with certified sludges. When optimized, these five extraction techniques are as much efficient with similar relative standard deviation. Whatever the extraction techniques used, the whole analysis protocol permits to quantify PAHs in the range of 0.09 to 0.9 mg/kg of dried sludges.
Magnetic Solid Phase Extraction Based on Oleic Acid Coated Fe3O4 for the Determination of Benzo[α]pyrene in Cigarette Smoke Coupled with High-Performance Liquid Chromatography.

PubMed

Feng, Shouai; Wei, Kang; Tian, Zhaofu; Li, Xiaolan; Meng, Dongling; Liao, Wenlong; Miao, Mingming; Yang, Yaling

2016-07-29

In this work, a simple and effective method based on magnetic solid-phase extraction combined with high-performance liquid chromatography was developed for the determination of benzo[α]pyrene (BaP) in cigarette smoke. Oleic acid coated Fe 3 O 4 (Fe 3 O 4 -OA) was synthesized and directly used as an efficient sorbent for the first time in magnetic solid-phase extraction (MSPE) procedure for the clean-up of BaP in cigarette smoke extracts. The synthesized Fe 3 O 4 -OA was characterized by transmission electron microscopy, X-ray diffraction and Fourier transformed infrared spectroscopy. The extraction via Fe 3 O 4 -OA was dispersed in the extracts of cigarette smoke followed by the magnetic isolation, acetonitrile-tetrahydrofuran (ACN-THF; v/v = 9:1) was used for desorption of the analyte. The effects of important parameters such as the amount of adsorbent, solution pH, the content of acetonitrile, temperature and sorption time were investigated. The method showed good linearity for the determination of BaP in the concentration range of 0.5-50 ng mL -1 with a regression coefficient (R 2 ) of 0.9987. The limit of detection and limit of quantification for BaP were obtained to be 0.12 and 0.41 ng mL -1 , respectively. The mean recoveries were in the range from 81.0% to 97.6% at low, medium, high spiked levels, and the relative standard deviations were in the range of 2.7-6.8%. Combined with high-performance liquid chromatography and fluorescence detection, a simple and effective method was developed for the analysis of BaP in cigarette smoke. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Higher urine 1-hydroxy pyrene glucuronide (1-OHPG) is associated with tobacco smoke exposure and drinking maté in healthy subjects from Rio Grande do Sul, Brazil

PubMed Central

Fagundes, Renato B; Abnet, Christian C; Strickland, Paul T; Kamangar, Farin; Roth, Mark J; Taylor, Philip R; Dawsey, Sanford M

2006-01-01

Background The highest rates of esophageal squamous cell carcinoma (ESCC) in Brazil occur in Rio Grande do Sul, the most southern state, which has incidence rates of 20.4/100,000/year for men and 6.5/100,000/year for women. Exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs) through tobacco smoke and other sources may increase the risk of ESCC. The aims of the current study were to investigate the degree and sources of PAH exposure of the inhabitants of this region of southern Brazil. Methods Two hundred healthy adults (half smokers, half non smokers, half male and half female) were recruited, given a standardized questionnaire, and asked to provide a urine sample for measurement of 1-hydroxypyrene glucuronide (1-OHPG), a PAH metabolite). Urine 1-OHPG concentrations were measured using immunoaffinity chromatography and synchronous fluorescence spectroscopy and urine cotinine was measured using a dipstick test. We examined factors associated with 1-OHPG concentration using Wilcoxon tests and multiple linear regression. Results Urine 1-hydroxypyrene glucuronide (1-OHPG) was successfully measured on 199 subjects. The median (interquartile range) of urine 1-OHPG in the 199 participants was 2.09 pmol/mL (0.51, 5.84). Tobacco smoke exposure and maté drinking were statistically significantly associated with higher urine 1-OHPG concentrations in the multivariate linear regression model. Conclusion Tobacco smoke and maté both contribute to high levels of benzo[a]pyrene exposure in the people of southern Brazil. This high PAH exposure may contribute to the high rates of ESCC observed in this population. The increased urine 1-OHPG concentrations associated with maté suggest that contaminants, not just thermal injury, may help explain the increased risk of ESCC previously reported for maté consumption. PMID:16729889
[Rapid identification of potato cultivars using NIR-excited fluorescence and Raman spectroscopy].

PubMed

Dai, Fen; Bergholt, Mads Sylvest; Benjamin, Arnold Julian Vinoj; Hong, Tian-Sheng; Zhiwei, Huang

2014-03-01

Potato is one of the most important food in the world. Rapid and noninvasive identification of potato cultivars plays a important role in the better use of varieties. In this study, The identification ability of optical spectroscopy techniques, including near-infrared (NIR) Raman spectroscopy and NIR fluorescence spectroscopy, for invasive detection of potato cultivars was evaluated. A rapid NIR Raman spectroscopy system was applied to measure the composite Raman and NIR fluorescence spectroscopy of 3 different species of potatoes (98 samples in total) under 785 nm laser light excitation. Then pure Raman and NIR fluorescence spectroscopy were abstracted from the composite spectroscopy, respectively. At last, the partial least squares-discriminant analysis (PLS-DA) was utilized to analyze and classify Raman spectra of 3 different types of potatoes. All the samples were divided into two sets at random: the calibration set (74samples) and prediction set (24 samples), the model was validated using a leave-one-out, cross-validation method. The results showed that both the NIR-excited fluorescence spectra and pure Raman spectra could be used to identify three cultivars of potatoes. The fluorescence spectrum could distinguish the Favorita variety well (sensitivity: 1, specificity: 0.86 and accuracy: 0.92), but the result for Diamant (sensitivity: 0.75, specificity: 0.75 and accuracy: 0. 75) and Granola (sensitivity: 0.16, specificity: 0.89 and accuracy: 0.71) cultivars identification were a bit poorer. We demonstrated that Raman spectroscopy uncovered the main biochemical compositions contained in potato species, and provided a better classification sensitivity, specificity and accuracy (sensitivity: 1, specificity: 1 and accuracy: 1 for all 3 potato cultivars identification) among the three types of potatoes as compared to fluorescence spectroscopy.
A fluorescent molecular sensor for pH windows in traditional and polymeric biocompatible micelles: comicellization of anionic species to shift and reshape the ON window.

PubMed

Cavallaro, Gennara; Giammona, Gaetano; Pasotti, Luca; Pallavicini, Piersandro

2011-09-12

A new approach is presented to obtain fluorescent sensors for pH windows that work in water and under biomimetic conditions. A single molecule that features all-covalently linked components is used, thus making it capable of working as a fluorescent sensor with an OFF/ON/OFF response to pH value. The components are a tertiary amine, a pyridine, and a fluorophore (pyrene). The forms with both protonated bases or both neutral bases quench the pyrene fluorescence, whereas the form with the neutral pyridine and protonated amine groups is fluorescent. The molecular sensor is also equipped with a long alkyl chain to make it highly hydrophobic in all its protonated and unprotonated forms, that is, either when neutral or charged. Accordingly, it can be confined at any pH value either in traditional (i.e., low-molecular-weight) nonionic surfactant micelles or inside polymeric, biocompatible micellar containers. Relevant for future applications in vivo, thanks to its strong hydrophobicity, no leakage of the molecular sensor is observed from the polymeric biocompatible micelles. Due to the proximity of the pyridine and amine functions in the molecular structure and the poor hydration inside the micelles, the observed pK(a) values are low so that the ON window is positioned at very low pH values. However, the window can be shifted to biologically relevant values by comicellization of anionic species. In particular, in the micelles of the nonionic surfactant TritonX-100, a shift of the ON window to pH 4-6 is obtained by addition of the anionic sodium dodecyl sulphate surfactant, whose negative charge promotes the stability of the protonated forms of the pyridine and amine fragments. In the case of the polymeric micelles, we introduce the use of the amphiphilic polystyrene sulfonate anionic polyelectrolyte, the comicellization of which induces a shift and sharpening of the ON window that is centered at pH 4. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Unraveling the interaction of hemoglobin with a biocompatible and cleavable oxy-diester-functionalized gemini surfactant.

PubMed

Akram, Mohd; Anwar, Sana; Bhat, Imtiyaz Ahmad; Kabir-Ud-Din

2017-03-01

Surfactant-protein mixtures have attracted considerable research interest in recent years at the interface of chemical biology and medicinal chemistry. Herein, the interaction between a green gemini surfactant (C 16 -E2O-C 16 ) and a redox protein hemoglobin was examined through a series of in vitro experimental techniques with an attempt to provide a comprehensive knowledge of the surfactant-protein binding interactions. Quantitative appraisal of the fluorescence/CV data showed that the binding of C 16 -E2O-C 16 to Hb leads to the formation of thermodynamically favorable non-covalent adduct with 1:1 stoichiometry. UV-vis spectra demonstrated that the effect of C 16 -E2O-C 16 on Hb is highly concentration dependent. Far-UV and near-UV CD spectra together elucidated the formation of molten globule state of Hb upon C 16 -E2O-C 16 addition. Temperature dependent CD explicated the effect of C 16 -E2O-C 16 on the thermal stability of Hb. Furthermore, the structural investigation of Hb via pyrene/synchronous/three-dimensional fluorescence and FT-IR spectroscopy provided the complementary information related to its microenvironmental and conformational changes. Computational studies delineated that C 16 -E2O-C 16 binds in the vicinity of β-37 Trp at the α 1 β 2 interface of Hb. Overall, this study is expected to clarify the binding mechanism between Hb/other congeners and surfactant at the molecular level that are known to have immense potential in biomedical and industrial areas. Copyright © 2016 Elsevier B.V. All rights reserved.
Vesicles from pH-regulated reversible gemini amino-acid surfactants as nanocapsules for delivery.

PubMed

Lv, Jing; Qiao, Weihong; Li, Zongshi

2016-10-01

Reversible transition from micelles to vesicles by regulating pH were realized by gemini amino-acid surfactants N,N'-dialkyl-N,N'-diacetate ethylenediamine. Measurement results of ζ-potential at different pH and DLS at varying solvents revealed that the protonation between H(+) and double NCH2COO(-) groups (generating NH(+)CH2COO(-)), expressed as pKa1 and pKa2, is the key driving force to control the aggregation behaviors of gemini surfactant molecule. Effect of pH on the bilayer structure was studied in detail by using steady-state fluorescence spectroscopy of hydrophobic pyrene and Coumarin 153 (C153) respectively and fluorescence resonance energy transfer (FRET) from C153 to Rhodamine 6G (R6G). Various pH-regulated and pH-reversible self-assemblies were obtained in one surfactant system. Vitamin D3 was encapsulated in vesicle bilayers to form nano-VD3-capsules as VD3 supplement agent for health care products. By using the electrostatic attraction between Ca(2+) and double -COO(-) groups, nano-VD3-capsules with Ca(2+) coated outermost layers were prepared as a formulation for VD3 and calcium co-supplement agent. DLS and TEM were performed to check stability and morphology of the nano-capsules. It is concluded that the pH-regulated gemini amino-acid surfactants can be used to construct colloidal systems for delivering hydrophobic drugs or nutritions without lipids at human physiological pH level. Copyright © 2016 Elsevier B.V. All rights reserved.
Poly(Acrylic Acid-b-Styrene) Amphiphilic Multiblock Copolymers as Building Blocks for the Assembly of Discrete Nanoparticles

PubMed Central

Greene, Anna C.; Zhu, Jiahua; Pochan, Darrin J.; Jia, Xinqiao; Kiick, Kristi L.

2011-01-01

In order to expand the utility of current polymeric micellar systems, we have developed amphiphilic multiblock copolymers containing alternating blocks of poly(acrylic acid) and poly(styrene). Heterotelechelic poly(tert-butyl acrylate-b-styrene) diblock copolymers containing an α-alkyne and an ω-azide were synthesized by atom transfer radical polymerization (ATRP), allowing control over the molecular weight while maintaining narrow polydispersity indices. The multiblock copolymers were constructed by copper-catalyzed azide-alkyne cycloaddition of azide-alkyne end functional diblock copolymers which were then characterized by 1H NMR, FT-IR and SEC. The tert-butyl moieties of the poly(tert-butyl acrylate-b-styrene) multiblock copolymers were easily removed to form the poly(acrylic acid-b-styrene) multiblock copolymer ((PAA-PS)9), which contained up to 9 diblock repeats. The amphiphilic multiblock (PAA-PS)9 (Mn = 73.3 kg/mol) was self-assembled by dissolution into tetrahydrofuran and extensive dialysis against deionized water for 4 days. The critical micelle concentration (CMC) for (PAA-PS)9 was determined by fluorescence spectroscopy using pyrene as a fluorescent probe and was found to be very low at 2 × 10-4 mg/mL. The (PAA-PS)9 multiblock was also analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The hydrodynamic diameter of the particles was found to be 11 nm. Discrete spherical particles were observed by TEM with an average particle diameter of 14 nm. The poly(acrylic acid) periphery of the spherical particles should allow for future conjugation of biomolecules. PMID:21552373
Analysis of fish bile with HPLC — fluorescence to determine environmental exposure to benzo(a)pyrene

USGS Publications Warehouse

Johnston, Eric P.; Baumann, Paul C.

1989-01-01

Brown bullhead from the Black River, Ohio, have a high incidence of liver neoplasia which is associated with elevated concentrations of polynuclear aromatic hydrocarbons (PAHs) in the sediment. We evaluated the use of biliary concentrations of benzo(a)pyrene [B(a)P] equivalents as a means for determining PAH exposure. Bile was collected from 16 brown bullheads and 8 common carp taken from each of two Lake Erie tributaries in Ohio, the industrialized Black River and the non-industrialized Old Woman Creek. Hatchery bullhead (n = 8) were used to determine base levels of PAHs. A high performance liquid chromatography (HPLC) — fluorescence technique was used to determine the concentration of B(a)P equivalents in the bile samples. The area of all peaks fluorescing at 380/430 nm was summed to give a single value for B(a)P equivalents in each sample. Concentrations of B(a)P equivalents generally reflected concentrations of PAH in sediment where fish were collected. Bile taken from Black River carp contained the highest concentration of B(a)P equivalents and was significantly different from all other groups. The value obtained for Black River bullhead was also high and was found to be significantly different from hatchery bullhead. B(a)P equivalents varied between carp and bullhead from the same habitat possibly because of differing food habits or metabolic pathways. However, our results indicate that relative levels of B(a)P equivalents in the bile of fish correspond well to B(a)P levels in sediment and may offer a means of determining environmental exposure of fish to the parent compound.
Effects of humic substances on the bioconcentration of polycyclic aromatic hydrocarbons: Correlations with spectroscopic and chemical properties of humic substances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haitzer, M.; Abbt-Braun, G.; Traunspurger, W.

1999-12-01

The presence of dissolved humic substances (HS, fulvic and humic acids) generally reduces the uptake of hydrophobic organic compounds into aquatic organisms. The extent of this effect depends both on the concentration and on the origin of the HS. The aim of this study was to investigate the role of qualitative differences between HS from different origins. The effects of seven different HS on the bioconcentration of pyrene and benzo[a]pyrene (BaP) in the nematode Caenorhabditis elegans were related to the spectroscopic and chemical properties of the HS. The effect of each humic material on the bioconcentration of pyrene or BaPmore » was quantified as a biologically determined partition coefficient K{sub DOC}. The authors observed significant linear relationships between K{sub DOC} and the atomic H/C ratio, the specific absorptivity at 254 nm, the content of aromatic carbons as determined by {sup 13}C nuclear magnetic resonance spectroscopy, the copper-complexing capacity, the content of phenolic OH groups, and the molecular weight of the HS. There was no discernible relationship of K{sub DOC} with the atomic (N + O)/C ratio, an indicator of the polarity of HS. Taken together, their results show that the variability in the effects of HS from different origins could be related to variations in bulk properties of the HS. Parameters describing the aromaticity of the humic materials seemed to be most useful for estimating effects of HS on the bioconcentration of pyrene and BaP.« less
Preservation of commonly applied fluorescent tracers in complex water samples

NASA Astrophysics Data System (ADS)

Cao, Viet; Schaffer, Mario; Jin, Yulan; Licha, Tobias

2017-06-01

Water sample preservation and pre-treatment are important steps for achieving accurate and reproductive results from tracer tests. However, this is particularly challenging for complex water mixtures prior to fluorescence analysis. In this study, the interference of iron and calcium precipitation with nine commonly applied conservative tracers, uranine, eosin, 1-naphthalene sulfonate, 1,5-naphthalene disulfonate, 2,6-naphthalene disulfonate, 4-amino-1-naphthalene sulfonate, 6-hydroxy-2-naphthalene sulfonate, 1,3,6-naphthalene trisulfonate, and 1,3,6,8-pyrene tetrasulfonate, was investigated in batch experiments. In general, the observed results are influenced by precipitates. A technique consisting of pH adjustment and centrifugation is described for preserving samples and avoiding the impact of these precipitates on the tracer test results.
Excitation-emission matrices and synchronous fluorescence spectroscopy for the diagnosis of gastrointestinal cancers

NASA Astrophysics Data System (ADS)

Genova, Ts; Borisova, E.; Penkov, N.; Vladimirov, B.; Zhelyazkova, A.; Avramov, L.

2016-06-01

We report the development of an improved fluorescence technique for cancer diagnostics in the gastrointestinal tract. We investigate the fluorescence of ex vivo colorectal (cancerous and healthy) tissue samples using excitation-emission matrix (EEM) and synchronous fluorescence spectroscopy (SFS) steady-state approaches. The obtained results are processed for revealing characteristic fluorescence spectral features with a valuable diagnostic meaning. The main tissue fluorophores, contributing to the observed fluorescence, are tyrosine, tryptophan, NADH, FAD, collagen and elastin. Based on the results of the Mann-Whitney test as useful parameters for differentiation of gastrointestinal cancer from normal mucosa, we suggest using excitation wavelengths in the range 300 - 360 nm for fluorescence spectroscopy and wavelengths intervals of 60 nm and 90 nm for SFS.
Binding mode dependent signaling for the detection of Cu2 +: An experimental and theoretical approach with practical applications

NASA Astrophysics Data System (ADS)

Ghosh, Soumen; Khan, Mehebub Ali; Ganguly, Aniruddha; Masum, Abdulla Al; Alam, Md. Akhtarul; Guchhait, Nikhil

2018-02-01

Two amido-schiff bases (3-Hydroxy-naphthalene-2-carboxylic acid pyren-1-ylmethylene-hydrazide and Naphthalene-2-carboxylic acid pyren-1-ylmethylene-hydrazide) have been synthesized having a common structural unit and only differs by a -OH group in the naphthalene ring. Both of them can detect Cu2 + ion selectively in semi-aqueous medium in distinctly different output modes (one detects Cu2 + by naked-eye color change where as the other detects Cu2 + by fluorescence enhancement). The difference in the binding of Cu 2 + with the compounds is the reason for this observation. The detection limit is found to be micromolar region for compound which contains -OH group whereas the compound without -OH group detects copper in nano-molar region. DFT calculations have been performed in order to demonstrate the structure of the compounds and their copper complexes. Practical utility has been explored by successful paper strip response of both the compounds. The biological applications have been evaluated in RAW 264.7.
Evaluation of pH-sensitive poly(β-amino ester)-graft-poly(ethylene glycol) and its usefulness as a pH-sensor and protein carrier.

PubMed

Kim, Min Sang; Gao, Guang Hui; Kang, Seong Woo; Lee, Doo Sung

2011-07-07

In this study, some possible biomedical applications of a pH-sensitive and amphiphilic copolymer as a pH sensor and protein delivery system are reported. PAE-g-PEG was used as a pH-sensitive polymer that can exhibit a sharp pH-dependent transition. Various fluorescent dyes including pyrene and RITC can be used to label the pH-sensitive polymer PAE-g-PEG, which was evaluated for protein encapsulation. pH-sensing was possible by observing excimer formation of the labeled pyrene via pH-dependent expansion of the polymeric chain. Also, it was confirmed that FITC-BSA could be entrapped in RITC-labeled pH-sensitive micelles of PAE-g-PEG by FRET. As a result, PAE-g-PEG can be a pH sensor and carrier for protein delivery. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Portable fluorescence lifetime spectroscopy system for in-situ interrogation of biological tissues

NASA Astrophysics Data System (ADS)

Saito Nogueira, Marcelo; Cosci, Alessandro; Teixeira Rosa, Ramon Gabriel; Salvio, Ana Gabriela; Pratavieira, Sebastião; Kurachi, Cristina

2017-12-01

Fluorescence spectroscopy and lifetime techniques are potential methods for optical diagnosis and characterization of biological tissues with an in-situ, fast, and noninvasive interrogation. Several diseases may be diagnosed due to differences in the fluorescence spectra of targeted fluorophores, when, these spectra are similar, considering steady-state fluorescence, others may be detected by monitoring their fluorescence lifetime. Despite this complementarity, most of the current fluorescence lifetime systems are not robust and portable, and not being feasible for clinical applications. We describe the assembly of a fluorescence lifetime spectroscopy system in a suitcase, its characterization, and validation with clinical measurements of skin lesions. The assembled system is all encased and robust, maintaining its mechanical, electrical, and optical stability during transportation, and is feasible for clinical measurements. The instrument response function measured was about 300 ps, and the system is properly calibrated. At the clinical study, the system showed to be reliable, and the achieved spectroscopy results support its potential use as an auxiliary tool for skin diagnostics.
Quantitative frequency-domain fluorescence spectroscopy in tissues and tissue-like media

NASA Astrophysics Data System (ADS)

Cerussi, Albert Edward

1999-09-01

In the never-ending quest for improved medical technology at lower cost, modern near-infrared optical spectroscopy offers the possibility of inexpensive technology for quantitative and non-invasive diagnoses. Hemoglobin is the dominant chromophore in the 700-900 nm spectral region and as such it allows for the optical assessment of hemoglobin concentration and tissue oxygenation by absorption spectroscopy. However, there are many other important physiologically relevant compounds or physiological states that cannot be effectively sensed via optical methods because of poor optical contrast. In such cases, contrast enhancements are required. Fluorescence spectroscopy is an attractive component of optical tissue spectroscopy. Exogenous fluorophores, as well as some endogenous ones, may furnish the desperately needed sensitivity and specificity that is lacking in near-infrared optical tissue spectroscopy. The main focus of this thesis was to investigate the generation and propagation of fluorescence photons inside tissues and tissue-like media (i.e., scattering dominated media). The standard concepts of fluorescence spectroscopy have been incorporated into a diffusion-based picture that is sometimes referred to as photon migration. The novelty of this work lies in the successful quantitative recovery of fluorescence lifetimes, absolute fluorescence quantum yields, fluorophore concentrations, emission spectra, and both scattering and absorption coefficients at the emission wavelength from a tissue-like medium. All of these parameters are sensitive to the fluorophore local environment and hence are indicators of the tissue's physiological state. One application demonstrating the capabilities of frequency-domain lifetime spectroscopy in tissue-like media is a study of the binding of ethidium bromide to bovine leukocytes in fresh milk. Ethidium bromide is a fluorescent dye that is commonly used to label DNA, and hence visualize chromosomes in cells. The lifetime of ethidium bromide increases by an order of magnitude upon binding to DNA. In this thesis, I demonstrated that the fluorescence photon migration model is capable of accurately determining the somatic cell count (SCC) in a milk sample. Although meant as a demonstration of fluorescence tissue spectroscopy, this specific problem has important implications for the dairy industry's warfare against subclinical mastitis (i.e., mammary gland inflammation), since the SCC is often used as an indication of bovine infection.
In-Vivo Fluorescence Spectroscopy Of Normal And Atherosclerotic Arteries

NASA Astrophysics Data System (ADS)

Deckelbaum, Lawrence I.; Sarembock, Ian J.; Stetz, Mark L.; O'Brien, Kenneth M.; Cutruzzola, Francis W.; Gmitro, Arthur F.; Ezekowitz, Michael D.

1988-06-01

Laser-induced fluorescence spectroscopy can discriminate atherosclerotic from normal arteries in-vitro and may thus potentially guide laser angioplasty. To evaluate the feasibility of laser-induced fluorescence spectroscopy in a living blood-filled arterial system we performed fiberoptic laser-induced fluorescence spectroscopy in a rabbit model of focal femoral atherosclerosis. A laser-induced fluorescence spectroscopy score was derived from stepwise linear regression analysis of in-vitro spectra to distinguish normal aorta (score>0) from atherosclerotic femoral artery (score<0). A 400 u silica fiber, coupled to a helium cadmium laser and optical multichannel analyzer, was inserted through a 5F catheter to induce and record in-vivo fluorescence from femoral and aortoiliac arteries. Arterial spectra could be recorded in all animals (n=10: 5 occlusions, 5 stenoses). Blood spectra were of low intensity and were easily distinguished from arterial spectra. The scores (mean ± SEM) for the in-vivo spectra were -0.69 +/- 0.29 for artherosclerotic femoral, and +0.54 ±. 0.15 for normal aorta (p<.01 p=NS compared to in-vitro spectra). In-vitro, a fiber tip to tissue distance <50 u was necessary for adequate arterial LIFS in blood. At larger distances low intensity blood spectra were recorded (1/20 the intensity of tissue spectra). Thus, fiberoptic laser-induced fluorescence spectroscopy can be sucessfully performed in a blood filled artery provided the fiber tip is approximated to the tissue.
Time-resolved fluorescence spectroscopy of human brain tumors

NASA Astrophysics Data System (ADS)

Marcu, Laura; Thompson, Reid C.; Garde, Smita; Sedrak, Mark; Black, Keith L.; Yong, William H.

2002-05-01

Fluorescence spectroscopy of the endogenous emission of brain tumors has been researched as a potentially important method for the intraoperative localization of brain tumor margins. In this study, we investigate the use of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) for demarcation of primary brain tumors by studying the time-resolved spectra of gliomas of different histologic grades. Time-resolved fluorescence (3 ns, 337 nm excitation) from excised human brain tumor show differences between the time-resolved emission of malignant glioma and normal brain tissue (gray and white matter). Our findings suggest that brain tumors can be differentiated from normal brain tissue based upon unique time-resolved fluorescence signature.
Fluorescence spectroscopy applied to orange trees

NASA Astrophysics Data System (ADS)

Marcassa, L. G.; Gasparoto, M. C. G.; Belasque, J., Jr.; Lins, E. C.; Dias Nunes, F.; Bagnato, V. S.

2006-05-01

In this work, we have applied laser-induced fluorescence spectroscopy to investigate biological processes in orange trees (Citrus aurantium L.). We have chosen to investigate water stress and Citrus Canker, which is a disease caused by the Xanthomonas axonopodis pv. citri bacteria. The fluorescence spectroscopy was investigated by using as an excitation source a 442-nm 15-mW HeCd gas multimode discharge laser and a 532-nm 10-mW Nd3+:YAG laser. The stress manifestation was detected by the variation of fluorescence ratios of the leaves at different wavelengths. The fluorescence ratios present a significant variation, showing the possibility to observe water stress by fluorescence spectrum. The Citrus Canker’s contaminated leaves were discriminated from the healthy leaves using a more complex analysis of the fluorescence spectra. However, we were unable to discriminate it from another disease, and new fluorescence experiments are planned for the future.
Sensitive Pb(2+) probe based on the fluorescence quenching by graphene oxide and enhancement of the leaching of gold nanoparticles.

PubMed

Shi, Xinhao; Gu, Wei; Peng, Weidong; Li, Bingyu; Chen, Ningning; Zhao, Kai; Xian, Yuezhong

2014-02-26

A novel strategy was developed for fluorescent detection of Pb(2+) in aqueous solution based on the fact that graphene oxide (GO) could quench the fluorescence of amino pyrene (AP)-grafted gold nanoparticles (AP-AuNPs) and Pb(2+) could accelerate the leaching rate of AuNPs in the presence of S2O3(2-). In this system, fluorescence reporter AP was grafted on AuNPs through the Au-N bond. In the presence of GO, the system shows fluorescence quenching because of π-π stacking between AP and GO. With the addition of Pb(2+) and S2O3(2-), the system displays fluorescence recovery, which is attributed to the fact that Pb(2+) could accelerate the leaching of the AuNPs from GO surfaces and release of AP into aqueous solution. Interestingly, the concentration of GO could control the fluorescence "turn-off" or "turn-on" for Pb(2+) detection. In addition, GO is also an excellent promoter for the acceleration of the leaching of AuNPs and shortening the analytical time to ∼15 min. Under the optimal conditions, the fluorescence Pb(2+) sensor shows a linear range from 2.0 × 10(-9) to 2.3 × 10(-7) mol/L, with a detection limit of 1.0 × 10(-10) mol/L.
Detection of polycyclic aromatic hydrocarbons (PAHs) in Medicago sativa L. by fluorescence microscopy.

PubMed

Alves, Wilber S; Manoel, Evelin A; Santos, Noemi S; Nunes, Rosane O; Domiciano, Giselli C; Soares, Marcia R

2017-04-01

Green technologies, such as phytoremediation, are effective for removing organic pollutants derived from oil and oil products, including polycyclic aromatic hydrocarbons (PAHs). Given the increasing popularity of these sustainable remediation techniques, methods based on fluorescence microscopy and multiphoton microscopy for the environmental monitoring of such pollutants have emerged in recent decades as effective tools for phytoremediation studies aimed at understanding the fate of these contaminants in plants. However, little is known about the cellular and molecular mechanisms involved in PAH uptake, responses and degradation by plants. Thus, the present study aimed to detect the location of pyrene, anthracene and phenanthrene using fluorescence microscopy techniques in shoots and roots of Medicago sativa L. (alfalfa) plants grown in artificially contaminated soil (150ppm PAHs) for 40days. Leaflet and root samples were then collected and observed under a fluorescence microscope to detect the presence of PAHs in various tissues. One important finding of the present study was intense fluorescence in the glandular secreting trichomes (GSTs) of plants grown in contaminated soil. These trichomes, with a previously unknown function, may be sites of PAH conjugation and degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.
Determination of Benzo[α]pyrene in Edible Oil Using Tetraoxocalix[2]arene[2]triazine Bonded Silica SPE Sorbent.

PubMed

Guo, Yun; Zhao, Wen-Jie; Deng, Zhi-Fen; Hongbo, Wang; Peng, Bin; Ma, Xue; Lan, Chen; Zhang, Shu-Sheng

2018-06-01

Benzo[α]pyrene (BaP) is a well-known carcinogen in edible oil. In this study, a method combined solid-phase extraction (SPE) with fluorescent detection was developed using tetraoxocalix[2]arene[2]triazine sorbent (SiO 2 -OCA) for the clean-up and enrichment of BaP. The interaction between SiO 2 -OCA and BaP involves a donor-acceptor complex mechanism. The experimental procedure was as follows: BaP was extracted from edible oil with DMF/H 2 O (9:1, v/v). Then, the ratio of DMF/H 2 O was adjusted to 1:2 prior to SPE. The final concentrate was analyzed using a fluorescence detector at excitation and emission wavelengths of 255 and 420 nm. The method was fully validated. The linearity was in the range of 0.1-100 μg kg -1 with a coefficient of 0.999. The limits of detection and quantification were 0.03 and 0.1 μg kg -1 , respectively. The average recoveries were in the range of 88.0-122.3%. The intraday and interday precisions were 6.8% and 9.2%, respectively. Compared with other methods, the method reported in this article shows a good detection limit, high reproducibility and recovery, and linearity over a broad concentration range. This established method was also applied to evaluate real samples. The concentration of six tested samples was below 5 μg kg -1 .
Portable fluorescence lifetime spectroscopy system for in-situ interrogation of biological tissues.

PubMed

Saito Nogueira, Marcelo; Cosci, Alessandro; Teixeira Rosa, Ramon Gabriel; Salvio, Ana Gabriela; Pratavieira, Sebastião; Kurachi, Cristina

2017-10-01

Fluorescence spectroscopy and lifetime techniques are potential methods for optical diagnosis and characterization of biological tissues with an in-situ, fast, and noninvasive interrogation. Several diseases may be diagnosed due to differences in the fluorescence spectra of targeted fluorophores, when, these spectra are similar, considering steady-state fluorescence, others may be detected by monitoring their fluorescence lifetime. Despite this complementarity, most of the current fluorescence lifetime systems are not robust and portable, and not being feasible for clinical applications. We describe the assembly of a fluorescence lifetime spectroscopy system in a suitcase, its characterization, and validation with clinical measurements of skin lesions. The assembled system is all encased and robust, maintaining its mechanical, electrical, and optical stability during transportation, and is feasible for clinical measurements. The instrument response function measured was about 300 ps, and the system is properly calibrated. At the clinical study, the system showed to be reliable, and the achieved spectroscopy results support its potential use as an auxiliary tool for skin diagnostics. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).
Interaction of Sodium Hyaluronate with a Biocompatible Cationic Surfactant from Lysine: A Binding Study.

PubMed

Bračič, Matej; Hansson, Per; Pérez, Lourdes; Zemljič, Lidija F; Kogej, Ksenija

2015-11-10

Mixtures of natural and biodegradable surfactants and ionic polysaccharides have attracted considerable research interest in recent years because they prosper as antimicrobial materials for medical applications. In the present work, interactions between the lysine-derived biocompatible cationic surfactant N(ε)-myristoyl-lysine methyl ester, abbreviated as MKM, and the sodium salt of hyaluronic acid (NaHA) are investigated in aqueous media by potentiometric titrations using the surfactant-sensitive electrode and pyrene-based fluorescence spectroscopy. The critical micelle concentration in pure surfactant solutions and the critical association concentration in the presence of NaHA are determined based on their dependence on the added electrolyte (NaCl) concentration. The equilibrium between the protonated (charged) and deprotonated (neutral) forms of MKM is proposed to explain the anomalous binding isotherms observed in the presence of the polyelectrolyte. The explanation is supported by theoretical model calculations of the mixed-micelle equilibrium and the competitive binding of the two MKM forms to the surface of the electrode membrane. It is suggested that the presence of even small amounts of the deprotonated form can strongly influence the measured electrode response. Such ionic-nonionic surfactant mixtures are a special case of mixed surfactant systems where the amount of the nonionic component cannot be varied independently as was the case for some of the earlier studies.
Real Time Quantification of Ultrafast Photoinduced Bimolecular Electron Transfer Rate: Direct Probing of the Transient Intermediate.

PubMed

Mukherjee, Puspal; Biswas, Somnath; Sen, Pratik

2015-08-27

Fluorescence quenching studies through steady-state and time-resolved measurements are inadequate to quantify the bimolecular electron transfer rate in bulk homogeneous solution due to constraints from diffusion. To nullify the effect of diffusion, direct evaluation of the rate of formation of a transient intermediate produced upon the electron transfer is essential. Methyl viologen, a well-known electron acceptor, produces a radical cation after accepting an electron, which has a characteristic strong and broad absorption band centered at 600 nm. Hence it is a good choice to evaluate the rate of photoinduced electron transfer reaction employing femtosecond broadband transient absorption spectroscopy. The time constant of the aforementioned process between pyrene and methyl viologen in methanol has been estimated to be 2.5 ± 0.4 ps using the same technique. The time constant for the backward reaction was found to be 14 ± 1 ps. These values did not change with variation of concentration of quencher, i.e., methyl viologen. Hence, we can infer that diffusion has no contribution in the estimation of rate constants. However, on changing the solvent from methanol to ethanol, the time constant of the electron transfer reaction has been found to increase and has accounted for the change in solvent reorganization energy.
Comparative studies on the interaction of caffeic acid, chlorogenic acid and ferulic acid with bovine serum albumin

NASA Astrophysics Data System (ADS)

Li, Shuang; Huang, Kelong; Zhong, Ming; Guo, Jun; Wang, Wei-zheng; Zhu, Ronghua

2010-10-01

The substitution of the hydrogen on aromatic and esterification of carboxyl group of the phenol compounds plays an important role in their bio-activities. In this paper, caffeic acid (CaA), chlorogenic acid (ChA) and ferulic acid (FA) were selected to investigate the binding to bovine serum albumin (BSA) using UV absorption spectroscopy, fluorescence spectroscopy and synchronous fluorescence spectroscopy. It was found that the methoxyl group substituting for the 3-hydroxyl group of CaA decreased the affinity for BSA and the esterification of carboxyl group of CaA with quinic acid increased the affinities. The affinities of ChA and FA with BSA were more sensitive to the temperature than that of CaA with BSA. Synchronous fluorescence spectroscopy and time-resolved fluorescence indicated that the Stern-Volmer plots largely deviated from linearity at high concentrations and were caused by complete quenching of the tyrosine fluorescence of BSA.
Early Amyloidogenic Oligomerization Studied through Fluorescence Lifetime Correlation Spectroscopy

PubMed Central

Paredes, Jose M.; Casares, Salvador; Ruedas-Rama, Maria J.; Fernandez, Elena; Castello, Fabio; Varela, Lorena; Orte, Angel

2012-01-01

Amyloidogenic protein aggregation is a persistent biomedical problem. Despite active research in disease-related aggregation, the need for multidisciplinary approaches to the problem is evident. Recent advances in single-molecule fluorescence spectroscopy are valuable for examining heterogenic biomolecular systems. In this work, we have explored the initial stages of amyloidogenic aggregation by employing fluorescence lifetime correlation spectroscopy (FLCS), an advanced modification of conventional fluorescence correlation spectroscopy (FCS) that utilizes time-resolved information. FLCS provides size distributions and kinetics for the oligomer growth of the SH3 domain of α-spectrin, whose N47A mutant forms amyloid fibrils at pH 3.2 and 37 °C in the presence of salt. The combination of FCS with additional fluorescence lifetime information provides an exciting approach to focus on the initial aggregation stages, allowing a better understanding of the fibrillization process, by providing multidimensional information, valuable in combination with other conventional methodologies. PMID:22949804
Effect of Bacillus subtilis and NTA-APG on pyrene dissipation in phytoremediation of nickel co-contaminated wetlands by Scirpus triqueter.

PubMed

Liu, Xiaoyan; Hu, Xiaoxin; Zhang, Xinying; Chen, Xueping; Chen, Jing; Yuan, Xiaoyu

2018-06-15

A complex mix of organic pollutants and heavy metal made the remediation of contaminated wetlands more difficult. Few research focus on the remediation for pyrene enhanced by chemical reagents and pyrene degrading bacteria in the nickel co-contaminated soil. In this paper, the effect of chemical reagents (nitrilotriacetic acid and alkyl polyglucoside) and Bacillus subtilis on pyrene dissipation in phytoremediation of nickel co-contaminated soil by Scirpus triqueter was investigated. Similar seedlings of Scirpus triqueter were moved to uncontaminated soil and pyrene-nickel co-contaminated soil. The pots (14.8 cm diameter and 8.8 cm height) were set up in greenhouse and treated in different ways. After 60 days, plant biomass, radial oxygen loss (ROL), soil dehydrogenase activity (DHA) and pyrene concentration in soil were determined. Results showed that ROL rate and DHA in different groups was positively correlated with pyrene dissipation from soil. In the process of remediation, chemical reagents might have an indirect slight effect on pyrene dissipation (pyrene dissipation increased 21%) by affecting DHA firstly and redistributing pyrene fractions in the presence of pyrene degrading bacteria. Pyrene degrading bacteria were likely to affect pyrene dissipation by impacting ROL rate and DHA and played a more vital role in contributing to pyrene dissipation (pyrene dissipation increased 45%) from wetland. This study demonstrated that phytoremediation for pyrene in nickel co-contaminated soil by Scirpus triqueter can be enhanced by the application of NTA-APG and pyrene degrading bacteria and they could be reasonably restore the ecological environment of PAH-contaminated wetlands. Copyright © 2018 Elsevier Inc. All rights reserved.
Evidence for phospholipid microdomain formation in liquid crystalline liposomes reconstituted with Escherichia coli lactose permease.

PubMed Central

Lehtonen, J Y; Kinnunen, P K

1997-01-01

The well-characterized integral membrane protein lactose (lac) permease from Escherichia coli was reconstituted together with trace amounts (molar fraction X = 0.005 of the total phospholipid) of different pyrene-labeled phospholipid analogs into 1-palmitoyl-2-oleoyl-sn-glycero-3-sn-glycero-3-phospho-rac'-glycerol (POPG) liposomes. Effects of lac permease on bilayer lipid dynamics were investigated by measuring the excimer-to-monomer fluorescence intensity ratio IE/IM. Compared to control vesicles, the presence of lac permease (at a protein:phospholipid stoichiometry P/L of 1:4.000) increased the rate of excimer formation by 1-palmitoyl-2[6-(pyren-1-yl)]decanoyl-sn-glycero-3-phosphocholine (PPDPC) by approximately fivefold. Decreasing P/L from approximately 1:4.000 to 1:7.600 decreased the IE/IM for PPDPC from 0.16 to 0.05, respectively. An increase in bilayer fluidity due to permease is unlikely, thus implying that the augmented IE/IM should arise from partial lateral segregation of PPDPC in the vesicles. This notion is supported by the further 38% increase in IE/IM observed for the pyrene-labeled Cys-148 lac permease reconstituted into POPG vesicles at P/L 1:4000. The importance of the length of the lipid-protein boundary is implicated by the reduction in IE/IM resulting from the aggregation of the lac permease in vesicles by a monoclonal antibody. Interestingly, excimer formation by 1-palmitoyl-2[6-(pyren-1-yl)hexanoyl-sn-glycero-3-phosphocholine (PPHPC) was enhanced only fourfold in the presence of lac permease. Results obtained with the corresponding pyrenyl phosphatidylglycerols and -methanols were qualitatively similar to those above, thus indicating that lipid headgroup-protein interactions are not involved. Inclusion of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamino-N-(5-fluoresce inthio- carbamoyl) (DPPF, X = 0.005) into reconstituted lactose permease vesicles containing PPDPC caused a nearly 90% decrease in excimer fluorescence, whereas in control vesicles lacking the reconstituted protein only 40% quenching was evident. The addition of 1,2-dipalmitoyl-sn-glycero-3-phospho-rac'-glycerol (DPPG) decreased IE/IM for PPDPC, revealing the driving force for the lateral segregation of this probe to become attenuated. More specifically for protein-free bilayers at XDPPG = 0.10 the rate of lateral diffusion of PPDPC in POPG is diminished, as evidenced by the 24% decrement in IE/IM, under these conditions the increase in IE/IM due to lac permease was strongly reduced, by approximately 84%. The present data are interpreted in terms of the hydrophobic mismatch theory, which predicts that integral membrane proteins will draw lipids of similar hydrophobic thickness into their vicinity. In brief, the approximate lengths of most of the predicted 12 hydrophobic, membrane-spanning alpha-helical segments of lactose permease range between 28.5 and 37.5 A and thus exceed the hydrophobic thickness of POPG of approximately 25.8 A. Therefore, to reduce the free energy of the assembly, longer lipids such as PPDPC and DPPF are accumulated in the immediate vicinity of lactose permease in fluid, liquid crystalline POPG bilayers. PMID:9138570
Using Quenching to Detect Corrosion on Sculptural Metalwork: A Real-World Application of Fluorescence Spectroscopy

ERIC Educational Resources Information Center

Hensen, Cory; Clare, Tami Lasseter; Barbera, Jack

2018-01-01

Fluorescence spectroscopy experiments are a frequently taught as part of upper-division teaching laboratories. To expose undergraduate students to an applied fluorescence technique, a corrosion detection method, using quenching, was adapted from authentic research for an instrumental analysis laboratory. In the experiment, students acquire…
Time-Resolved Magnetic Field Effects Distinguish Loose Ion Pairs from Exciplexes

PubMed Central

2013-01-01

We describe the experimental investigation of time-resolved magnetic field effects in exciplex-forming organic donor–acceptor systems. In these systems, the photoexcited acceptor state is predominantly deactivated by bimolecular electron transfer reactions (yielding radical ion pairs) or by direct exciplex formation. The delayed fluorescence emitted by the exciplex is magnetosensitive if the reaction pathway involves loose radical ion pair states. This magnetic field effect results from the coherent interconversion between the electronic singlet and triplet radical ion pair states as described by the radical pair mechanism. By monitoring the changes in the exciplex luminescence intensity when applying external magnetic fields, details of the reaction mechanism can be elucidated. In this work we present results obtained with the fluorophore-quencher pair 9,10-dimethylanthracene/N,N-dimethylaniline (DMA) in solvents of systematically varied permittivity. A simple theoretical model is introduced that allows discriminating the initial state of quenching, viz., the loose ion pair and the exciplex, based on the time-resolved magnetic field effect. The approach is validated by applying it to the isotopologous fluorophore-quencher pairs pyrene/DMA and pyrene-d10/DMA. We detect that both the exciplex and the radical ion pair are formed during the initial quenching stage. Upon increasing the solvent polarity, the relative importance of the distant electron transfer quenching increases. However, even in comparably polar media, the exciplex pathway remains remarkably significant. We discuss our results in relation to recent findings on the involvement of exciplexes in photoinduced electron transfer reactions. PMID:24041160
Multiphoton spectral analysis of benzo[a]pyrene uptake and metabolism in a rat liver cell line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barhoumi, Rola, E-mail: rmouneimne@cvm.tamu.edu; Mouneimne, Youssef; Ramos, Ernesto

2011-05-15

Dynamic analysis of the uptake and metabolism of polycyclic aromatic hydrocarbons (PAHs) and their metabolites within live cells in real time has the potential to provide novel insights into genotoxic and non-genotoxic mechanisms of cellular injury caused by PAHs. The present work, combining the use of metabolite spectra generated from metabolite standards using multiphoton spectral analysis and an 'advanced unmixing process', identifies and quantifies the uptake, partitioning, and metabolite formation of one of the most important PAHs (benzo[a]pyrene, BaP) in viable cultured rat liver cells over a period of 24 h. The application of the advanced unmixing process resulted inmore » the simultaneous identification of 8 metabolites in live cells at any single time. The accuracy of this unmixing process was verified using specific microsomal epoxide hydrolase inhibitors, glucuronidation and sulfation inhibitors as well as several mixtures of metabolite standards. Our findings prove that the two-photon microscopy imaging surpasses the conventional fluorescence imaging techniques and the unmixing process is a mathematical technique that seems applicable to the analysis of BaP metabolites in living cells especially for analysis of changes of the ultimate carcinogen benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide. Therefore, the combination of the two-photon acquisition with the unmixing process should provide important insights into the cellular and molecular mechanisms by which BaP and other PAHs alter cellular homeostasis.« less
Self-doped polyaniline multifunctional optical probes in confined nanostructure for pH sensing

NASA Astrophysics Data System (ADS)

Hong, Yoochan; Hwang, Seungyeon; Yang, Jaemoon

2017-07-01

We have successfully fabricated nanocomposite, which is composed of polyaniline (PAni) and pyrene butyric acid (Pyba) via solvent shift method, and the outer layer was enclosed by Tween 80 as a surfactant. First of all, the various ratios between PAni and Pyba were applied for synthesis of polyaniline nanocomposite, and an identical condition for exhibition of proper absorbance and fluorescence properties was found out. The morphology of polyaniline nanocomposite was confirmed via scanning electron microscopic imaging and hydrodynamic size was also confirmed by dynamic light scattering method. We demonstrated that confined self-doped polyaniline nanocomposite as a pH sensing agent are preserved in the doped state even at a neutral pH value. Especially, PAni exhibited strong convertible property at absorbance spectra, on the other hand, Pyba showed changing property at fluorescence spectra at various pH values. In conclude, this polyaniline nanocomposite can accomplish as a fine nanoagent expressing absorbance and fluorescence properties according to surrounding pH values.
Different sensing modes of fluoride and acetate based on a calix[4]arene with 25,27-bistriazolylmethylpyrenylacetamides.

PubMed

Hung, Hao-Chih; Chang, Yung-Yu; Luo, Liyang; Hung, Chen-Hsiung; Diau, Eric Wei-Guang; Chung, Wen-Sheng

2014-02-01

25,27-Bis{1'-N-(1-pyrenyl)-aminocarbonylmethyl-1H-[1',2',3']tri-azolyl-4'-methoxy}-26,28-dihydroxycalix[4]arene, 4, is synthesized as a fluorescent chemosensor for the selective detection of both anions and ion pairs in MeCN. Sensor 4 uses bis-triazoles as ligands to bind a metal ion, bis-amides and bis-triazoles as the sites to recognize anions, and pyrenes as fluorophores. Among eight anions screened, chemosensor 4 showed a marked fluorescence change toward F(-), H2PO4(-) and AcO(-), but 4 responded to each anion in a distinct way. In the presence of F(-) at low concentrations, the dynamic excimer emission of compound 4 at λ(max) 482 nm was quenched, but an emission at λ(max) 472 nm appeared at large doses of F(-). A control compound 6 showed very similar red shifts in the UV-vis and excitation spectra as 4 did, and its 472 nm emission band grew as the fluoride doses increased. Thus, the growth of the 472 nm emission of 4 and 6 in the presence of excess F(-) may be because strong H-bonding interactions of amido protons with F(-) favoured the formation of pyrene dimers in the ground state with charge transfer characteristics. The addition of H2PO4(-), unlike F(-), to a solution of 4 showed an enhanced monomer emission but a decreased excimer emission (λ(max) 482 nm). Adding AcO(-) to 4 produced a systematic change from a dynamic excimer (λ(max) 482 nm) to λ(max) 472 nm but with very little change in the UV-vis spectrum. Time-resolved fluorescence measurements on compound 6 with F(-) and AcO(-) confirmed that the 472 nm emission band mainly came from static excimers for the former, but was partly from a dynamic excimer for the latter because it contained a growth component in the fluorescence decay traces. Without pre-treatment with an anion, chemosensor 4 showed recognition of only metal ions Cu(2+), Hg(2+) and Cr(3+), but it became sensitive to Ag(+) when it was pretreated with fluoride.

Spectral characterization of the fluorescent components present in humic substances, fulvic acid and humic acid mixed with pure benzo(a)pyrene solution.

PubMed

El Fallah, Rawa; Rouillon, Régis; Vouvé, Florence

2018-06-15

The fate of benzo(a)pyrene (BaP), a ubiquitous contaminant reported to be persistent in the environment, is largely controlled by its interactions with the soil organic matter. In the present study, the spectral characteristics of fluorophores present in the physical fractions of the soil organic matter were investigated in the presence of pure BaP solution. After extraction of humic substances (HSs), and their fractionation into fluvic acid (FA) and humic acid (HA), two fluorescent compounds (C 1 and C 2 ) were identified and characterized in each physical soil fraction, by means of fluorescence excitation-emission matrices (FEEMs) and Parallel Factor Analysis (PARAFAC). Then, to each type of fraction having similar DOC content, was added an increasing volume of pure BaP solution in attempt to assess the behavior of BaP with the fluorophores present in each one. The application of FEEMs-PARAFAC method validated a three-component model that consisted of the two resulted fluorophores from HSs, FA and HA (C 1 and C 2 ) and a BaP-like fluorophore (C 3 ). Spectral modifications were noted for components C 2 HSs (C 2 in humic substances fraction) (λex/λem: 420/490-520 nm), C 2 FA (C 2 in fulvic acid fraction) (λex/λem: 400/487(517) nm) and C 1 HA (C 1 in humic acid fraction) (λex/λem: 350/452(520) nm). We explored the impact of increasing the volume of the added pure BaP solution on the scores of the fluorophores present in the soil fractions. It was found that the scores of C 2 HSs, C 2 FA, and C 1 HA increased when the volume of the added pure BaP solution increased. Superposition of the excitation spectra of these fluorophores with the emission spectrum of BaP showed significant overlaps that might explain the observed interactions between BaP and the fluorescent compounds present in SOM physical fractions. Copyright © 2018 Elsevier B.V. All rights reserved.
Spectral characterization of the fluorescent components present in humic substances, fulvic acid and humic acid mixed with pure benzo(a)pyrene solution

NASA Astrophysics Data System (ADS)

El Fallah, Rawa; Rouillon, Régis; Vouvé, Florence

2018-06-01

The fate of benzo(a)pyrene (BaP), a ubiquitous contaminant reported to be persistent in the environment, is largely controlled by its interactions with the soil organic matter. In the present study, the spectral characteristics of fluorophores present in the physical fractions of the soil organic matter were investigated in the presence of pure BaP solution. After extraction of humic substances (HSs), and their fractionation into fluvic acid (FA) and humic acid (HA), two fluorescent compounds (C1 and C2) were identified and characterized in each physical soil fraction, by means of fluorescence excitation-emission matrices (FEEMs) and Parallel Factor Analysis (PARAFAC). Then, to each type of fraction having similar DOC content, was added an increasing volume of pure BaP solution in attempt to assess the behavior of BaP with the fluorophores present in each one. The application of FEEMs-PARAFAC method validated a three-component model that consisted of the two resulted fluorophores from HSs, FA and HA (C1 and C2) and a BaP-like fluorophore (C3). Spectral modifications were noted for components C2HSs (C2 in humic substances fraction) (λex/λem: 420/490-520 nm), C2FA (C2 in fulvic acid fraction) (λex/λem: 400/487(517) nm) and C1HA (C1 in humic acid fraction) (λex/λem: 350/452(520) nm). We explored the impact of increasing the volume of the added pure BaP solution on the scores of the fluorophores present in the soil fractions. It was found that the scores of C2HSs, C2FA, and C1HA increased when the volume of the added pure BaP solution increased. Superposition of the excitation spectra of these fluorophores with the emission spectrum of BaP showed significant overlaps that might explain the observed interactions between BaP and the fluorescent compounds present in SOM physical fractions.
Fluorescence lifetime correlation spectroscopy for precise concentration detection in vivo by background subtraction

NASA Astrophysics Data System (ADS)

Gärtner, Maria; Mütze, Jörg; Ohrt, Thomas; Schwille, Petra

2009-07-01

In vivo studies of single molecule dynamics by means of Fluorescence correlation spectroscopy can suffer from high background. Fluorescence lifetime correlation spectroscopy provides a tool to distinguish between signal and unwanted contributions via lifetime separation. By studying the motion of the RNA-induced silencing complex (RISC) within two compartments of a human cell, the nucleus and the cytoplasm, we observed clear differences in concentration as well as mobility of the protein complex between those two locations. Especially in the nucleus, where the fluorescence signal is very weak, a correction for background is crucial to provide reliable results of the particle number. Utilizing the fluorescent lifetime of the different contributions, we show that it is possible to distinguish between the fluorescent signal and the autofluorescent background in vivo in a single measurement.
Detectability limit and uncertainty considerations for laser induced fluorescence spectroscopy in flames

NASA Technical Reports Server (NTRS)

Daily, J. W.

1978-01-01

Laser induced fluorescence spectroscopy of flames is discussed, and derived uncertainty relations are used to calculate detectability limits due to statistical errors. Interferences due to Rayleigh scattering from molecules as well as Mie scattering and incandescence from particles have been examined for their effect on detectability limits. Fluorescence trapping is studied, and some methods for reducing the effect are considered. Fluorescence trapping places an upper limit on the number density of the fluorescing species that can be measured without signal loss.
[The effect of alpha-tocopherol and ionol on the physical structure of the membranes of rat liver microsomes under conditions of antioxidant insufficiency].

PubMed

Gubskiĭ, Iu I; Boldeskul, A E; Primak, R G; Zadorina, O V

1989-01-01

Physiochemical conformity of the alpha-tocopherol interaction with hepatic microsomal membranes has been studied by means of fluorescent probes (pyrene and 1-anilinonaphthalene-8-sulphonate). The microsomal membrane microviscosity is shown to sharply decrease under conditions of the antioxidant deficiency with vitamin E expelled into animals normalizes microviscosity, but feebly influences the microsomal surface charge. Microcalorimetry has been used to establish that penetration of tocopherol into microsomal membranes was accompanied by the exothermic effect.
Studies on Structural, Optical, Thermal and Electrical Properties of Perylene-Doped p-terphenyl Luminophors.

PubMed

Desai, Netaji K; Mahajan, Prasad G; Bhopate, Dhanaji P; Dalavi, Dattatray K; Kamble, Avinash A; Gore, Anil H; Dongale, Tukaram D; Kolekar, Govind B; Patil, Shivajirao R

2018-01-01

A simple solid state reaction technique was employed for the preparation of polycrystalline luminophors of p-terphenyl containing different amounts of perylene followed by spectral characterization techniques viz. XRD, SEM, TGA-DSC, UV-Visible spectroscopy, thermo-electrical conductivity, fluorescence spectroscopy, fluorescence life time spectroscopy and temperature dependent fluorescence. X-ray diffraction profiles of the doped p-terphenyl reveal well-defined and sharp peaks indicate homogeneity and crystallinity. The SEM micrograph of pure p-terphenyl exhibit flakes like grains and then compact and finally gets separately with perylene amounts. The observed results indicate that closed packed crystal structures of doped p-terphenyl during crystal formation. The band gaps estimated from UV-visible spectroscopy decreased from 5.20 to 4.10 eV, while thermo-electrical conductivity increases with perylene content. The fluorescence spectra showed partial quenching of p-terphenyl fluorescence and simultaneously sensitization of perylene fluorescence at the excitation wavelength of p-terphenyl (290 nm) due to excitation energy transfer from p-terphenyl to perylene. The observed sensitization results are in harmony with intense blue color seen in fluorescence microscopy images and has high demand in scintillation process.
Noncontact point spectroscopy guided by two-channel fluorescence imaging in a hamster cheek pouch model

NASA Astrophysics Data System (ADS)

Yang, Victor X.; Yeow, Jenny; Lilge, Lothar D.; Kost, James; Mang, Thomas S.; Wilson, Brian C.

1999-07-01

A system for in vivo, fluorescence image-guided, non-contact point fluorescence spectroscopy is presented. A 442 nm HeCd laser is used as the fluorescence excitation source. An intensified CCD serves as the detector for both imaging and spectroscopy, on which two regions of 300 X 300 pixels were used for green (500 +/- 18 nm) and red (630 +/- 18 nm) imaging channels, and a strip of 600 X 120 pixels are used for emission spectroscopy (450 - 750 nm). At a working distance of 40 mm, the system has a spatial resolution of 0.16 mm and a spectral resolution of 5 nm. System performance is demonstrated in a carcinogenesis model in hamsters, where tumors were induced by painting DMBA in the cheek pouch. Autofluorescence and Photofrin-induced fluorescence measurements were performed every 2 weeks during the 18 weeks of tumor induction. Punch biopsies on selected animals were taken for histological staging. The results show that autofluorescence fluorescence can distinguish dysplasia from normal mucosal tissue model, utilizing the peak red intensity (or the red-to-green intensity ratio). Photofrin-induced fluorescence was superior to autofluorescence for differentiating high grade dysplasia from invasive cancer.
Multi-Photon Micro-Spectroscopy of Biological Specimens

DTIC Science & Technology

2000-07-01

Micro-spectroscopy, multi-photon fluorescence spectroscopy, second harmonic generation, plant tissues, stem, chloroplast, protoplast, maize, Arabidopsis...harmonic generation (SHG) in the plant cell 5wall. In this case, micro-spectroscopy provides a means of verification that, indeed, SHG occurs in plant ...fluorescence microscopy -the response of plant cells to high intensity illumination," Micron (in press) 2000. 3. H.-C. Huang and C. -C Chen, "Genome
Characterization and kinetics of surface functionalization and binding of biologically and chemically significant molecules

NASA Astrophysics Data System (ADS)

Steiner, Rachel

The purpose of this project is to investigate intermolecular interactions of organic molecular assemblies. By understanding the structure and physical interactions in these assemblies, we gain insights into practical applications for nanoscale systems built upon these surface structures. It is possible for organic chemists to create many forms of modified organic molecules, functionalizing them with specific reactive end groups. Through surface functionalization, enabling covalent or highly associative binding, it is possible to create ordered molecular assemblies of these molecules. Scientists can study the nature of this structure and the intermolecular interactions through spectroscopic, optical, and scattering experiments. To understand the self-assembly process in molecular systems, we preliminarily created monolayer films on silica substrates with a variety of organic molecules. In particular, we functionalized silica substrates with hydroxyl groups and covalently bound acid chloride functionalized aromatic compounds, with and without an underlying adhesion layer of 3-aminopropyltriethoxysilane. We characterized the monolayer assemblies with ellipsometry, UV-vis absorption spectroscopy, FTIR spectroscopy, and fluorescence/photoemission spectroscopy, obtaining a quantitative measure of the molecular surface coverage. In order to understand the nature of these molecular assemblies, we also pursued an in-depth kinetic study to control and optimize the monolayer formation process. Through use of UV-vis spectroscopy, we determined that the monolayer formation can best be modeled with diffusion-limited Langmuir kinetics. Specifically, we concluded that for anthracene acid chloride in dichloromethane the average diffusion coefficient was 1.6x10-7 cm2/sec. Additionally, we find we are able to achieve surface coverages of approximately 2x1014 molecules/cm2. Having established the ability to create ordered molecular assemblies, through surface functionalization, enabling covalent or highly associative binding, we continued to explore the field of molecular assemblies by studying the binding and structure of molecules to carbon nanostructures. Previous studies have shown that alkyl side chains and aromatic compounds, such as pyrene, will bind non-covalently to the sidewalls of carbon nanotubes through pi-pi interactions. We explored functionalization of carbon nanotubes and graphene by using microscopy to examine the adsorption of biomolecules onto nanotube sidewalls and graphene.
Application of fluorescence spectroscopy and imaging in the detection of a photosensitizer in photodynamic therapy

NASA Astrophysics Data System (ADS)

Zang, Lixin; Zhao, Huimin; Zhang, Zhiguo; Cao, Wenwu

2017-02-01

Photodynamic therapy (PDT) is currently an advanced optical technology in medical applications. However, the application of PDT is limited by the detection of photosensitizers. This work focuses on the application of fluorescence spectroscopy and imaging in the detection of an effective photosenzitizer, hematoporphyrin monomethyl ether (HMME). Optical properties of HMME were measured and analyzed based on its absorption and fluorescence spectra. The production mechanism of its fluorescence emission was analyzed. The detection device for HMME based on fluorescence spectroscopy was designed. Ratiometric method was applied to eliminate the influence of intensity change of excitation sources, fluctuates of excitation sources and photo detectors, and background emissions. The detection limit of this device is 6 μg/L, and it was successfully applied to the diagnosis of the metabolism of HMME in the esophageal cancer cells. To overcome the limitation of the point measurement using fluorescence spectroscopy, a two-dimensional (2D) fluorescence imaging system was established. The algorithm of the 2D fluorescence imaging system is deduced according to the fluorescence ratiometric method using bandpass filters. The method of multiple pixel point addition (MPPA) was used to eliminate fluctuates of signals. Using the method of MPPA, SNR was improved by about 30 times. The detection limit of this imaging system is 1.9 μg/L. Our systems can be used in the detection of porphyrins to improve the PDT effect.
Combined fluorescence-Raman spectroscopy measurements with an optical fiber probe for the diagnosis of melanocytic lesions

NASA Astrophysics Data System (ADS)

Cosci, Alessandro; Cicchi, Riccardo; Rossari, Susanna; De Giorgi, Vincenzo; Massi, Daniela; Pavone, Francesco S.

2012-02-01

We have designed and developed an optical fiber-probe for spectroscopic measurements on human tissues. The experimental setup combines fluorescence spectroscopy and Raman spectroscopy in a multidimensional approach. Concerning fluorescence spectroscopy, the excitation is provided by two laser diodes, one emitting in the UV (378 nm) and the other emitting in the visible (445 nm). These two lasers are used to selectively excite fluorescence from NADH and FAD, which are among the brightest endogenous fluorophores in human tissues. For Raman and NIR spectroscopy, the excitation is provided by a third laser diode with 785 nm excitation wavelength. Laser light is delivered to the tissue through the central optical fiber of a fiber bundle. The surrounding 48 fibers of the bundle are used for collecting fluorescence and Raman and for delivering light to the spectrograph. Fluorescence and Raman spectra are acquired on a cooled CCD camera. The instrument has been tested on fresh human skin biopsies clinically diagnosed as malignant melanoma, melanocytic nevus, or healthy skin, finding an optimal correlation with the subsequent histological exam. In some cases our examination was not in agreement with the clinical observation, but it was with the histological exam, demonstrating that the system can potentially contribute to improve clinical diagnostic capabilities and hence reduce the number of unnecessary biopsies.
Cytidine-directed rapid synthesis of water-soluble and highly yellow fluorescent bimetallic AuAg nanoclusters.

PubMed

Zhang, Yuanyuan; Jiang, Hui; Ge, Wei; Li, Qiwei; Wang, Xuemei

2014-09-16

Fluorescent gold/silver nanoclusters templated by DNA or oligonucleotides have been widely reported since DNA or oligonucleotides could be designed to position a few metal ions at close proximity prior to their reduction, but nucleoside-templated synthesis is more challenging. In this work, a novel type of strategy taking cytidine (C) as template to rapid synthesis of fluorescent, water-soluble gold and silver nanoclusters (C-AuAg NCs) has been developed. The as-prepared C-AuAg NCs have been characterized by UV-vis absorption spectroscopy, fluorescence, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and inductively coupled plasma mass spectroscopy (ICP-MS). The characterizations demonstrate that C-AuAg NCs with a diameter of 1.50 ± 0.31 nm, a quantum yield ∼9%, and an average lifetime ∼6.07 μs possess prominent fluorescence properties, good dispersibility, and easy water solubility, indicating the promising application in bioanalysis and biomedical diagnosis. Furthermore, this strategy by rapid producing of highly fluorescent nanoclusters could be explored for the possible recognition of some disease-related changes in blood serum. This raises the possibility of their promising application in bioanalysis and biomedical diagnosis.
Polycyclic aromatic hydrocarbons in commercial brands of dry whole soybeans for direct human consumption.

PubMed

Garcia, Laura Pereira; Gomes, Fernanda M L; Tfouni, Silvia; Vicente, Eduardo; Savi, Geovana D; Santos, Karolina; Scussel, Vildes M

2017-03-01

A total of 13 polycyclic aromatic hydrocarbons (PAHs) were surveyed in dry whole soybeans (Glycine max L.) sold for human consumption. The analysed samples were commercialised in vegetarian shops and food stores in Southern Brazil regions. The determination of PAHs levels was carried out by high performance liquid chromatography (HPLC)with fluorescence detection. PAHs were present in 89.7% of the samples. Chrysene (Chy) and 5 methyl chrysene (5MeChy) were the main PAHs detected (76.9% and 71.8%, respectively) followed by dibenzo(ai)pyrene (DaiP), however in a much less percentage of samples (23.1%). Apart from those PAHs, also benzo(a)antracene (BaA), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF) and benzo(a)pyrene(BaP) were found. The ΣPAH levels in the positive samples ranged from 0.80 to 38.78 µg kg -1 , with exception of one sample that reached 204.46 µg kg -1 (ΣPAHs of six compounds). Despite the present contamination there are no maximum limits set for PAHs in soybeans.
Studying the influence of stem composition in pH-sensitive molecular beacons onto their sensing properties.

PubMed

Dembska, Anna; Kierzek, Elzbieta; Juskowiak, Bernard

2017-10-16

Intracellular sensing using fluorescent molecular beacons is a potentially useful strategy for real-time, in vivo monitoring of important cellular events. This work is focused on evaluation of pyrene excimer signaling molecular beacons (MBs) for the monitoring of pH changes in vitro as well as inside living cells. The recognition element in our MB called pHSO (pH-sensitive oligonucleotide) is the loop enclosing cytosine-rich fragment that is able to form i-motif structure in a specific pH range. However, alteration of a sequence of the 6 base pairs containing stem of MB allowed the design of pHSO probes that exhibited different dynamic pH range and possessed slightly different transition midpoint between i-motif and open loop configuration. Moreover, this conformational transition was accompanied by spectral changes showing developed probes different pyrene excimer-monomer emission ratio triggered by pH changes. The potential of these MBs for intracellular pH sensing is demonstrated on the example of HeLa cells line. Copyright © 2017 Elsevier B.V. All rights reserved.
Native fluorescence spectroscopy of thymus and fat tissues

NASA Astrophysics Data System (ADS)

Tang, Gui C.; Oz, Mehmet C.; Reid, V.; Steinglass, K.; Ginsberg, Mark D.; Jacobowitz, Larry; Alfano, Robert R.

1993-08-01

Fluorescence spectroscopy of the human thymus gland and surrounding mediastinal fat were measured to evaluate this approach in distinguishing between thymus and fat tissues during therapeutic surgery for myasthenia gravis disease.
Two-dimensional fluorescence spectroscopy of uranium isotopes in femtosecond laser ablation plumes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, Mark C.; Brumfield, Brian E.; LaHaye, Nicole

Here, we demonstrate measurement of uranium isotopes in femtosecond laser ablation plumes using two-dimensional fluorescence spectroscopy (2DFS). The high-resolution, tunable CW-laser spectroscopy technique clearly distinguishes atomic absorption from 235U and 238U in natural and highly enriched uranium metal samples. We present analysis of spectral resolution and analytical performance of 2DFS as a function of ambient pressure. Simultaneous measurement using time-resolved absorption spectroscopy provides information on temporal dynamics of the laser ablation plume and saturation behavior of fluorescence signals. The rapid, non-contact measurement is promising for in-field, standoff measurements of uranium enrichment for nuclear safety and security.
Two-dimensional fluorescence spectroscopy of uranium isotopes in femtosecond laser ablation plumes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, Mark C.; Brumfield, Brian E.; LaHaye, Nicole L.

We demonstrate measurement of uranium isotopes in femtosecond laser ablation plumes using two-dimensional fluorescence spectroscopy (2DFS). The high-resolution, tunable CW-laser spectroscopy technique clearly distinguishes atomic absorption from 235U and 238U in natural and highly enriched uranium metal samples. We present analysis of spectral resolution and analytical performance of 2DFS as a function of ambient pressure. Simultaneous measurement using time-resolved absorption spectroscopy provides information on temporal dynamics of the laser ablation plume and saturation behavior of fluorescence signals. The rapid, non-contact measurement is promising for in-field, standoff measurements of uranium enrichment for nuclear safety and security applications.
Two-dimensional fluorescence spectroscopy of uranium isotopes in femtosecond laser ablation plumes

DOE PAGES

Phillips, Mark C.; Brumfield, Brian E.; LaHaye, Nicole; ...

2017-06-19

Here, we demonstrate measurement of uranium isotopes in femtosecond laser ablation plumes using two-dimensional fluorescence spectroscopy (2DFS). The high-resolution, tunable CW-laser spectroscopy technique clearly distinguishes atomic absorption from 235U and 238U in natural and highly enriched uranium metal samples. We present analysis of spectral resolution and analytical performance of 2DFS as a function of ambient pressure. Simultaneous measurement using time-resolved absorption spectroscopy provides information on temporal dynamics of the laser ablation plume and saturation behavior of fluorescence signals. The rapid, non-contact measurement is promising for in-field, standoff measurements of uranium enrichment for nuclear safety and security.
Efficient synthesis of highly fluorescent nitrogen-doped carbon dots for cell imaging using unripe fruit extract of Prunus mume

NASA Astrophysics Data System (ADS)

Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel; Sethuraman, Mathur Gopalakrishnan; Lee, Yong Rok

2016-10-01

Highly fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized using the extract of unripe Prunus mume (P. mume) fruit by a simple one step hydrothermal-carbonization method. The N-CDs were synthesized at different pH ranges, 2.3, 5, 7, and 9. The pH of the P. mume extract was adjusted using an aqueous ammonia solution (25%). The optical properties of N-CDs were examined by UV-vis and fluorescence spectroscopy. The N-CDs synthesized at pH 9 emitted high fluorescence intensity compared to other obtained N-CDs. The N-CDs synthesized at pH 9 was further characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform-infra red (FT-IR) spectroscopy. HR-TEM showed that the average size of the synthesized N-CDs was approximately 9 nm and the interlayer distance was 0.21 nm, which was validated by XRD. The graphitic nature of the synthesized N-CDs were confirmed by Raman spectroscopy. XPS and FT-IR spectroscopy confirmed the doping of the nitrogen moiety over the synthesized CDs. The synthesized nitrogen doped CDs (N-CDs) were low toxicity and were used as a staining probe for fluorescence cell imaging.
Comparative evaluation of differential laser-induced perturbation spectroscopy as a technique to discriminate emerging skin pathology

NASA Astrophysics Data System (ADS)

Kozikowski, Raymond T.; Smith, Sarah E.; Lee, Jennifer A.; Castleman, William L.; Sorg, Brian S.; Hahn, David W.

2012-06-01

Fluorescence spectroscopy has been widely investigated as a technique for identifying pathological tissue; however, unrelated subject-to-subject variations in spectra complicate data analysis and interpretation. We describe and evaluate a new biosensing technique, differential laser-induced perturbation spectroscopy (DLIPS), based on deep ultraviolet (UV) photochemical perturbation in combination with difference spectroscopy. This technique combines sequential fluorescence probing (pre- and post-perturbation) with sub-ablative UV perturbation and difference spectroscopy to provide a new spectral dimension, facilitating two improvements over fluorescence spectroscopy. First, the differential technique eliminates significant variations in absolute fluorescence response within subject populations. Second, UV perturbations alter the extracellular matrix (ECM), directly coupling the DLIPS response to the biological structure. Improved biosensing with DLIPS is demonstrated in vivo in a murine model of chemically induced skin lesion development. Component loading analysis of the data indicates that the DLIPS technique couples to structural proteins in the ECM. Analysis of variance shows that DLIPS has a significant response to emerging pathology as opposed to other population differences. An optimal likelihood ratio classifier for the DLIPS dataset shows that this technique holds promise for improved diagnosis of epithelial pathology. Results further indicate that DLIPS may improve diagnosis of tissue by augmenting fluorescence spectra (i.e. orthogonal sensing).

Photonic crystal enhanced fluorescence immunoassay on diatom biosilica.

PubMed

Squire, Kenneth; Kong, Xianming; LeDuff, Paul; Rorrer, Gregory L; Wang, Alan X

2018-05-16

Fluorescence biosensing is one of the most established biosensing methods, particularly fluorescence spectroscopy and microscopy. These are two highly sensitive techniques but require high grade electronics and optics to achieve the desired sensitivity. Efforts have been made to implement these methods using consumer grade electronics and simple optical setups for applications such as point-of-care diagnostics, but the sensitivity inherently suffers. Sensing substrates, capable of enhancing fluorescence are thus needed to achieve high sensitivity for such applications. In this paper, we demonstrate a photonic crystal-enhanced fluorescence immunoassay biosensor using diatom biosilica, which consists of silica frustules with sub-100 nm periodic pores. Utilizing the enhanced local optical field, the Purcell effect and increased surface area from the diatom photonic crystals, we create ultrasensitive immunoassay biosensors that can significantly enhance fluorescence spectroscopy as well as fluorescence imaging. Using standard antibody-antigen-labeled antibody immunoassay protocol, we experimentally achieved 100× and 10× better detection limit with fluorescence spectroscopy and fluorescence imaging respectively. The limit of detection of the mouse IgG goes down to 10 -16 M (14 fg/mL) and 10 -15 M (140 fg/mL) for the two respective detection modalities, virtually sensing a single mouse IgG molecule on each diatom frustule. The effectively enhanced fluorescence imaging in conjunction with the simple hot-spot counting analysis method used in this paper proves the great potential of diatom fluorescence immunoassay for point-of-care biosensing. Scanning electron microscope image of biosilica diatom frustule that enables significant enhancement of fluorescence spectroscopy and fluorescence image. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Clarification of the binding model of lead(II) with a highly sensitive and selective fluoroionophore sensor by spectroscopic and structural study

NASA Astrophysics Data System (ADS)

Ma, Lijun; Li, Yue; Li, Lei; Wu, Yuqing; Buchet, Rene; Ding, Yihong

2009-03-01

The detection of lead ion is very important both in environment and in biological systems because of its toxicity. A fluoroionophore sensor, N-[4(1-pyrene)-butyroyl]- L-tryptophan (PLT), distinguishing Pb 2+ from other 12 metal ions and exhibiting a very high sensitivity (0.15 μM) in aqueous solution, has been reported. The present study describes the spectroscopic clarification of the intrinsic differences of the binding model between PLT with Pb 2+ and with other ions. The fluorescent property of solid metal carboxylates reflects a character of the metal complex in solution, which results in a facility to solve problems by using solid sample of complex and vibrational spectroscopy. Both FT-infrared and Raman spectroscopy are employed to clarify the binding model between lead ion and its high sensitive and selective fluoroionophore sensor PLT, and essentially to explain why the metal ions other than Pb 2+ cannot response to PLT. The IR spectral data clearly show that a bridging bidentate coordination occurs when PLT is coordinated with Cu 2+ and Zn 2+; while a chelating bidentate coordination between the carboxyl anion and Pb 2+ exists in PLT-Pb, which is a new information beyond the NMR results in previous report. Meanwhile, the present study also indicates a characteristic interaction of lead ion and indole ring as well as the hydrogen bonding between amide groups. Furthermore, the quantum chemical calculations at the DFT level confirm the spectral and structural information of PLT-Pb 2+ proposed by experiments. Thus, the type of coordination, the interaction of the indole ring with the metal ion, and the hydrogen bonding between amide groups in PLT-Pb are likely responsible for the high selectivity of PLT to the lead(II) ion.
Clarification of the binding model of lead(II) with a highly sensitive and selective fluoroionophore sensor by spectroscopic and structural study.

PubMed

Ma, Lijun; Li, Yue; Li, Lei; Wu, Yuqing; Buchet, Rene; Ding, Yihong

2009-03-01

The detection of lead ion is very important both in environment and in biological systems because of its toxicity. A fluoroionophore sensor, N-[4(1-pyrene)-butyroyl]-l-tryptophan (PLT), distinguishing Pb(2+) from other 12 metal ions and exhibiting a very high sensitivity (0.15microM) in aqueous solution, has been reported. The present study describes the spectroscopic clarification of the intrinsic differences of the binding model between PLT with Pb(2+) and with other ions. The fluorescent property of solid metal carboxylates reflects a character of the metal complex in solution, which results in a facility to solve problems by using solid sample of complex and vibrational spectroscopy. Both FT-infrared and Raman spectroscopy are employed to clarify the binding model between lead ion and its high sensitive and selective fluoroionophore sensor PLT, and essentially to explain why the metal ions other than Pb(2+) cannot response to PLT. The IR spectral data clearly show that a bridging bidentate coordination occurs when PLT is coordinated with Cu(2+) and Zn(2+); while a chelating bidentate coordination between the carboxyl anion and Pb(2+) exists in PLT-Pb, which is a new information beyond the NMR results in previous report. Meanwhile, the present study also indicates a characteristic interaction of lead ion and indole ring as well as the hydrogen bonding between amide groups. Furthermore, the quantum chemical calculations at the DFT level confirm the spectral and structural information of PLT-Pb(2+) proposed by experiments. Thus, the type of coordination, the interaction of the indole ring with the metal ion, and the hydrogen bonding between amide groups in PLT-Pb are likely responsible for the high selectivity of PLT to the lead(II) ion.
Free volume dependent fluorescence property of PMMA composite: Positron annihilation studies

NASA Astrophysics Data System (ADS)

Ravindrachary, V.; Praveena, S. D.; Bhajantri, R. F.; Ismayil, Crasta, Vincent

2013-02-01

The free volume related fluorescence properties of chalcone chromophore [1-(4-methylphenyl)-3-(4-N, N, dimethylaminophenyl)-2-propen-1-one doped Poly(methyl methacrylate) have been studied using fluorescence spectroscopy and Positron Annihilation lifetime spectroscopy techniques. The fluorescence spectra show that the fluorescence behavior depends on the free volume dependent polymer microstructure and varies with dopant concentration with in the composite. The origin and variation of fluorescence is understood by twisted internal charge transfer state as well as free volume. The Positron annihilation study shows that the free volume related microstructure of the composite is vary with doping level.
Shell-Isolated Tip-Enhanced Raman and Fluorescence Spectroscopy.

PubMed

Huang, Ya-Ping; Huang, Sheng-Chao; Wang, Xiang-Jie; Bodappa, Nataraju; Li, Chao-Yu; Yin, Hao; Su, Hai-Sheng; Meng, Meng; Zhang, Hua; Ren, Bin; Yang, Zhi-Lin; Zenobi, Renato; Tian, Zhong-Qun; Li, Jian-Feng

2018-06-18

Tip-enhanced Raman spectroscopy can provide molecular fingerprint information with ultrahigh spatial resolution, but the tip will be easily contaminated, thus leading to artifacts. It also remains a great challenge to establish tip-enhanced fluorescence because of the quenching resulting from the proximity of the metal tip. Herein, we report shell-isolated tip-enhanced Raman and fluorescence spectroscopies by employing ultrathin shell-isolated tips fabricated by atomic layer deposition. Such shell-isolated tips not only show outstanding electromagnetic field enhancement in TERS but also exclude interference by contaminants, thus greatly promoting applications in solution. Tip-enhanced fluorescence has also been achieved using these shell-isolated tips, with enhancement factors of up to 1.7×10 3 , consistent with theoretical simulations. Furthermore, tip-enhanced Raman and fluorescence signals are acquired simultaneously, and their relative intensities can be manipulated by changing the shell thickness. This work opens a new avenue for ultrahigh resolution surface analysis using plasmon-enhanced spectroscopies. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
[A new class of exciplex-formed probe detect of specific sequence DNA].

PubMed

Li, Qing-Yong; Zu, Yuan-Gang; Lü, Hong-Yan; Wang, Li-Min

2009-07-01

The present research was to develop the exciplex-based fluorescence detection of DNA. A SNP-containing region of cytochrome P450 2C9 DNA systems was evaluated to define some of the structural and associated requirement of this new class of exciplex-formed probe, and a 24-base target was selected which contains single-nucleotide polymorphisms (SNP) in genes coding for cytochrome P450. The two probes were all 12-base to give coverage of a 24-base target region to ensure specificity within the human genome. Exciplex partners used in this study were prepared using analogous phosphoramide attachment to the 3'- or 5'-phosphate group of the appropriate oligonucleotide probes. The target effectively assembled its own detector by hybridization from components which were non-fluorescent at the detection wavelength, leading to the huge improvement in terms of decreased background. This research provides details of the effects of different partner, position of partners and different excitation wavelengths for the split-oligonucleotide probe system for exciplex-based fluorescence detection of DNA. This study demonstrates that the emission intensity of the excimer formed by new pyrene derivative is the highest in these excimer and exciplex, and the excimer is easy to be formed and not sensitive to the position of partners. However the exciplex formed by the new pyrene derivative and naphthalene emitted strongly at -505 nm with large Stokes shifts (120-130 nm), and the monomer emission at 390 and 410 nm is nearly zero. Excitation wavelength of 400 nm is the best for I(e505)/I(m410) (exciplex emission at 505 nm/monomer emission at 410 nm) of the exciplex. This method features lower background and high sensitivity. Moreover the exciplex is sensitive to the steric factor, different position of partners and microenvironment, so this exciplex system is promising and could be tried to identify the SNP genes.
Infrared fluorescence from PAHs in the laboratory

NASA Technical Reports Server (NTRS)

Cherchneff, Isabelle; Barker, John R.

1989-01-01

Several celestial objects, including UV rich regions of planetary and reflection nebulae, stars, H II regions, and extragalactic sources, are characterized by the unidentified infrared emission bands (UIR bands). A few years ago, it was proposed that polycyclic aromatic hydrocarbon species (PAHs) are responsible for most of the UIR bands. This hypothesis is based on a spectrum analysis of the observed features. Comparisons of observed IR spectra with lab absorption spectra of PAHs support the PAH hypothesis. An example spectrum is represented, where the Orion Bar 3.3 micron spectrum is compared with the absorption frequencies of the PAHs Chrysene, Pyrene, and Coronene. The laser excited 3.3 micron emission spectrum is presented from a gas phase PAH (azulen). The infrared fluorescence theory (IRF) is briefly explained, followed by a description of the experimental apparatus, a report of the results, and discussion.
Quantification of Coffea arabica and Coffea canephora var. robusta concentration in blends by means of synchronous fluorescence and UV-Vis spectroscopies.

PubMed

Dankowska, A; Domagała, A; Kowalewski, W

2017-09-01

The potential of fluorescence, UV-Vis spectroscopies as well as the low- and mid-level data fusion of both spectroscopies for the quantification of concentrations of roasted Coffea arabica and Coffea canephora var. robusta in coffee blends was investigated. Principal component analysis was used to reduce data multidimensionality. To calculate the level of undeclared addition, multiple linear regression (PCA-MLR) models were used with lowest root mean square error of calibration (RMSEC) of 3.6% and root mean square error of cross-validation (RMSECV) of 7.9%. LDA analysis was applied to fluorescence intensities and UV spectra of Coffea arabica, canephora samples, and their mixtures in order to examine classification ability. The best performance of PCA-LDA analysis was observed for data fusion of UV and fluorescence intensity measurements at wavelength interval of 60nm. LDA showed that data fusion can achieve over 96% of correct classifications (sensitivity) in the test set and 100% of correct classifications in the training set, with low-level data fusion. The corresponding results for individual spectroscopies ranged from 90% (UV-Vis spectroscopy) to 77% (synchronous fluorescence) in the test set, and from 93% to 97% in the training set. The results demonstrate that fluorescence, UV, and visible spectroscopies complement each other, giving a complementary effect for the quantification of roasted Coffea arabica and Coffea canephora var. robusta concentration in blends. Copyright © 2017 Elsevier B.V. All rights reserved.
Analysis of tetrahydroxylated benzo[a]pyrene isomers in hair as biomarkers of exposure to benzo[a]pyrene.

PubMed

Grova, Nathalie; Hardy, Emilie M; Meyer, Pauline; Appenzeller, Brice M R

2016-03-01

A first gas chromatography-tandem mass spectrometry (GC-MS/MS) method was designed for analysis of four tetrahydroxylated benzo[a]pyrene metabolites (benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydrotetrol, benzo[a]pyrene-r-7,t-8,t-9,t-10-tetrahydrotetrol, benzo[a]pyrene-r-7,t-8,c-9,c-10-tetrahydrotetrol, and benzo[a]pyrene-r-7,t-8,c-9,t-10-tetrahydrotetrol) in hair. Hair powder extract was submitted to liquid-solid extraction, followed by C18 solid-phase purification. The analytes were derivatized with use of N-methyl-N-(trimethylsilyl)trifluoroacetamide and then analyzed by GC-MS/MS in negative chemical ionization mode. The calibration curve was linear from the limit of quantification (LOQ) to 20 pg/mg in hair. The coefficient of determination of the calibration curve was more than 0.975 for all the analytes investigated. The LOQs ranged from 0.075 to 0.2 pg/mg in hair. The method was afterward applied to the analysis of hair of 16 rats randomly allocated to experimental groups receiving 16 polycyclic aromatic hydrocarbons solubilized in oil at 0 or 0.8 mg/kg body weight by oral administration three times per week for 90 days. The analysis of monohydroxylated and dihydroxylated benzo[a]pyrenes was conducted in parallel by GC-MS/MS on the same samples. All tetrahydroxylated benzo[a]pyrene isomers were detected in hair samples collected from rats exposed to polycyclic aromatic hydrocarbons. Benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydrotetrol, the most abundant isomer in hair of treated rats, was also the principal isomer released in DNA adduct hydrolysis in humans. Moreover, the benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydrotetrol concentrations in hair were significantly greater than those of 2-hydroxybenzo[a]pyrene, 1-hydroxybenzo[a]pyrene, 7-hydroxybenzo[a]pyrene, and 4-hydroxybenzo[a]pyrene and similar to those of 9-hydroxybenzo[a]pyrene and 3-hydroxybenzo[a]pyrene. The method was also sufficiently sensitive to monitor environmental levels of exposure because two hair specimens in the eight analyzed from smokers were above the LOQ for benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydrotetrol and benzo[a]pyrene-r-7,t-8,c-9,t-10-tetrahydrotetrol. This study therefore demonstrated that tetrahydroxylated benzo[a]pyrenes in hair might be a useful biomarker for the assessment of both the general population and occupationally exposed workers.
Label-free imaging and spectroscopy for early detection of cervical cancer.

PubMed

Jing, Yueyue; Wang, Yulan; Wang, Xinyi; Song, Chuan; Ma, Jiong; Xie, Yonghui; Fei, Yiyan; Zhang, Qinghua; Mi, Lan

2018-05-01

The label-free imaging and spectroscopy method was studied on cervical unstained tissue sections obtained from 36 patients. The native fluorescence spectra of tissues are analyzed by the optical redox ratio (ORR), which is defined as fluorescence intensity ratio between NADH and FAD, and indicates the metabolism change with the cancer development. The ORRs of normal tissues are consistently higher than those of precancer or cancerous tissues. A criterion line of ORR at 5.0 can be used to discriminate cervical precancer/cancer from normal tissues. The sensitivity and specificity of the native fluorescence spectroscopy method for cervical cancer diagnosis are determined as 100% and 91%. Moreover, the native fluorescence spectroscopy study is much more sensitive on the healthy region of cervical precancer/cancer patients compared with the traditional clinical staining method. The results suggest label-free imaging and spectroscopy is a fast, highly sensitive and specific method on the detection of cervical cancer. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Influence of tea saponin on enhancing accessibility of pyrene and cadmium phytoremediated with Lolium multiflorum in co-contaminated soils.

PubMed

Wang, Qian; Liu, Xiaoyan; Zhang, Xinying; Hou, Yunyun; Hu, Xiaoxin; Liang, Xia; Chen, Xueping

2016-03-01

Tea saponin (TS), a kind of biodegradable surfactant, was chosen to improve the accessible solubilization of pyrene and cadmium (Cd) in co-contaminated soils cultivated Lolium multiflorum. TS obviously improved the accessibility of pyrene and Cd for L. multiflorum to accelerate the process of accumulation and elimination of the pollutants. The chemical forms of Cd was transformed from Fe-Mn oxides and associated to carbonates fractions into exchangeable fractions by adding TS in single Cd and pyrene-Cd contaminated soils. Moreover, the chemical forms of pyrene were transformed from associated fraction into bioaccessible fraction by adding TS in pyrene and pyrene-Cd contaminated soils. In pyrene-Cd contaminated soil, the exchangeable fraction of Cd was hindered in the existence of pyrene, and bioaccessible fraction of pyrene was promoted by the cadmium. Besides, in the process of the pyrene degradation and Cd accumulation, the effect could be improved by the elongation of roots with adding TS, and the microorganism activity was stimulated by TS to accelerate the removal of pollutions. Therefore, Planting L. multiflorum combined with adding TS would be an effective method on the phytoremediation of organics and heavy metals co-contaminated soils.
Time-Gated Raman Spectroscopy for Quantitative Determination of Solid-State Forms of Fluorescent Pharmaceuticals.

PubMed

Lipiäinen, Tiina; Pessi, Jenni; Movahedi, Parisa; Koivistoinen, Juha; Kurki, Lauri; Tenhunen, Mari; Yliruusi, Jouko; Juppo, Anne M; Heikkonen, Jukka; Pahikkala, Tapio; Strachan, Clare J

2018-04-03

Raman spectroscopy is widely used for quantitative pharmaceutical analysis, but a common obstacle to its use is sample fluorescence masking the Raman signal. Time-gating provides an instrument-based method for rejecting fluorescence through temporal resolution of the spectral signal and allows Raman spectra of fluorescent materials to be obtained. An additional practical advantage is that analysis is possible in ambient lighting. This study assesses the efficacy of time-gated Raman spectroscopy for the quantitative measurement of fluorescent pharmaceuticals. Time-gated Raman spectroscopy with a 128 × (2) × 4 CMOS SPAD detector was applied for quantitative analysis of ternary mixtures of solid-state forms of the model drug, piroxicam (PRX). Partial least-squares (PLS) regression allowed quantification, with Raman-active time domain selection (based on visual inspection) improving performance. Model performance was further improved by using kernel-based regularized least-squares (RLS) regression with greedy feature selection in which the data use in both the Raman shift and time dimensions was statistically optimized. Overall, time-gated Raman spectroscopy, especially with optimized data analysis in both the spectral and time dimensions, shows potential for sensitive and relatively routine quantitative analysis of photoluminescent pharmaceuticals during drug development and manufacturing.
Fluorescent Sterols and Cholesteryl Esters as Probes for Intracellular Cholesterol Transport

PubMed Central

Solanko, Katarzyna A.; Modzel, Maciej; Solanko, Lukasz M.; Wüstner, Daniel

2015-01-01

Cholesterol transport between cellular organelles comprised vesicular trafficking and nonvesicular exchange; these processes are often studied by quantitative fluorescence microscopy. A major challenge for using this approach is producing analogs of cholesterol with suitable brightness and structural and chemical properties comparable with those of cholesterol. This review surveys currently used fluorescent sterols with respect to their behavior in model membranes, their photophysical properties, as well as their transport and metabolism in cells. In the first part, several intrinsically fluorescent sterols, such as dehydroergosterol or cholestatrienol, are discussed. These polyene sterols (P-sterols) contain three conjugated double bonds in the steroid ring system, giving them slight fluorescence in ultraviolet light. We discuss the properties of P-sterols relative to cholesterol, outline their chemical synthesis, and explain how to image them in living cells and organisms. In particular, we show that P-sterol esters inserted into low-density lipoprotein can be tracked in the fibroblasts of Niemann–Pick disease using high-resolution deconvolution microscopy. We also describe fluorophore-tagged cholesterol probes, such as BODIPY-, NBD-, Dansyl-, or Pyrene-tagged cholesterol, and eventual esters of these analogs. Finally, we survey the latest developments in the synthesis and use of alkyne cholesterol analogs to be labeled with fluorophores by click chemistry and discuss the potential of all approaches for future applications. PMID:27330304
Potential of Fluorescence Imaging Techniques To Monitor Mutagenic PAH Uptake by Microalga

PubMed Central

2015-01-01

Benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon (PAH), is one of the major environmental pollutants that causes mutagenesis and cancer. BaP has been shown to accumulate in phytoplankton and zooplankton. We have studied the localization and aggregation of BaP in Chlorella sp., a microalga that is one of the primary producers in the food chain, using fluorescence confocal microscopy and fluorescence lifetime imaging microscopy with the phasor approach to characterize the location and the aggregation of BaP in the cell. Our results show that BaP accumulates in the lipid bodies of Chlorella sp. and that there is Förster resonance energy transfer between BaP and photosystems of Chlorella sp., indicating the close proximity of the two molecular systems. The lifetime of BaP fluorescence was measured to be 14 ns in N,N-dimethylformamide, an average of 7 ns in Bold’s basal medium, and 8 ns in Chlorella cells. Number and brightness analysis suggests that BaP does not aggregate inside Chlorella sp. (average brightness = 5.330), while it aggregates in the supernatant. In Chlorella grown in sediments spiked with BaP, in 12 h the BaP uptake could be visualized using fluorescence microscopy. PMID:25020149
Synthesis of highly monodisperse particles composed of a magnetic core and fluorescent shell.

PubMed

Nagao, Daisuke; Yokoyama, Mikio; Yamauchi, Noriko; Matsumoto, Hideki; Kobayashi, Yoshio; Konno, Mikio

2008-09-02

Highly monodisperse particles composed of a magnetic silica core and fluorescent polymer shell were synthesized with a combined technique of heterocoagulation and soap-free emulsion polymerization. Prior to heterocoagulation, monodisperse, submicrometer-sized silica particles were prepared with the Stober method, and magnetic nanoparticles were prepared with a modified Massart method in which a cationic silane coupling agent of N-trimethoxysilylpropyl- N, N, N-trimethylammonium chloride was added just after coprecipitation of Fe (2+) and Fe (3+). The silica particles with negative surface potential were heterocoagulated with the magnetic nanoparticles with positive surface potential. The magnetic silica particles obtained with the heterocoagulation were treated with sodium silicate to modify their surfaces with silica. In the formation of a fluorescent polymer shell onto the silica-coated magnetic silica cores, an amphoteric initiator of 2,2'-azobis[ N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was used to control the colloidal stability of the magnetic cores during the polymer coating. The polymerization of St in the presence of a hydrophobic fluorophore of pyrene could coat the cores with fluorescent polymer shells, resulting in monodisperse particles with a magnetic silica core and fluorescent polymer shell. Measurements of zeta potential for the composite particles in different pH values indicated that the composite particles had an amphoteric property originating from VA-057 initiator.
Optical spectroscopy for quantitative sensing in human pancreatic tissues

NASA Astrophysics Data System (ADS)

Wilson, Robert H.; Chandra, Malavika; Lloyd, William; Chen, Leng-Chun; Scheiman, James; Simeone, Diane; McKenna, Barbara; Mycek, Mary-Ann

2011-07-01

Pancreatic adenocarcinoma has a five-year survival rate of only 6%, largely because current diagnostic methods cannot reliably detect the disease in its early stages. Reflectance and fluorescence spectroscopies have the potential to provide quantitative, minimally-invasive means of distinguishing pancreatic adenocarcinoma from normal pancreatic tissue and chronic pancreatitis. The first collection of wavelength-resolved reflectance and fluorescence spectra and time-resolved fluorescence decay curves from human pancreatic tissues was acquired with clinically-compatible instrumentation. Mathematical models of reflectance and fluorescence extracted parameters related to tissue morphology and biochemistry that were statistically significant for distinguishing between pancreatic tissue types. These results suggest that optical spectroscopy has the potential to detect pancreatic disease in a clinical setting.
"Sizing" the oligomers of Azami Green fluorescent protein with FCS and antibunching

NASA Astrophysics Data System (ADS)

Temirov, Jamshid; Werner, James H.; Goodwin, Peter M.; Bradbury, Andrew R. M.

2012-02-01

Fluorescent proteins are invaluable molecules in fluorescence microscopy and spectroscopy. The size and brightness of fluorescent proteins often dictates the application they may be used for. While a monomeric protein may be the least perturbative structure for labeling a protein in a cell, often oligomers (dimers and tetramers) of fluorescent proteins can be more stable. However, from a quantitative microscopy standpoint, it is important to realize the photophysical properties of monomers do not necessarily multiply by their number when they form oligomers. In this work we studied oligomerization states of the Azami Green (AG) protein with fluorescence correlation spectroscopy (FCS) and photon antibunching or photon pair correlation spectroscopy (PPCS). FCS was used to measure the hydrodynamic size of the oligomers, whereas antibunching was used to count the number of fluorescent emitters in the oligomers. The results exhibited that the dimers of AG were single emitters and the tetramers were dual-emitters, indicative of dipole-dipole interactions and energy transfer between the monomeric units. We also used these methods to estimate the number of fluorescent proteins displayed on T7 phage molecules.
Removal of pyrene and benzo(a)pyrene micropollutant from water via adsorption by green synthesized iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Hassan, Saad S. M.; Abdel-Shafy, Hussein I.; Mansour, Mona S. M.

2018-03-01

Polycyclic aromatic hydrocarbons (PAHs) in water are classified as organic micropollutants, which are carcinogenic even in very low concentration (ppb). In this study the green synthesized iron oxide nanoparticles (IONPs) were green synthesized at room temperature by using pomegranate peel extract. The green synthesized IONPs were used for adsorbing benzo(a)pyrene and pyrene (PAHs) from water. Factors affecting the adsorption were investigated. These factors are: nanoparticles dose, pH, temperature, and initial concentration of PAHs. The overall results showed that the maximum adsorption capacities of IONPs towards pyrene and benzo(a)pyrene were 2.8 and 0.029 mg g-1, respectively. The thermodynamic study indicated an exothermic adsorption process of pyrene and benzo(a)pyrene. The kinetic and isotherm studies were carried out. The obtained data revealed that the adsorption process follows a pseudo-second order mechanism and obeys Langmuir isotherm model. In addition, the IONPs proved to be a potential candidate for the adsorption of pyrene and benzo(a)pyrene even after five cycles of use and regeneration. The investigation was extended using semi-pilot plant to remove the studied PAHs from artificially contaminated water. The results showed that the IONPs was capable to remove the pyrene and benzo (a) pyrene at the rate of 98.5 and 99%, respectively. It also can be used as disinfectant.
Cold and drought stress in combination with pyrene exposure: studies with Protaphorura armata (Collembola: Onychiuridae).

PubMed

Sjursen, Heidi; Holmstrup, Martin

2004-02-01

Adult survival of the springtail Protaphorura armata exposed to pyrene, a common soil pollutant, was investigated in combination with cold and drought stress, in three separate experiments. (1) A drought stress imposed subsequent to pyrene exposure in soil resulted in a significant decrease in springtail survival, when compared with controls exposed to pyrene and subsequently to 100% relative humidity. (2) A previous exposure to drought stress resulted in slightly improved survival of pyrene exposure at a concentration of 10mg/kg, but not at higher pyrene concentrations. When comparing tests 1 and 2, better survival was found in the latter test. When comparing the drought survival of springtails that had been previously exposed to pyrene with drought survival of springtails with no previous history of pyrene exposure, survival was significantly lower in the former. (3) Springtail survival of pyrene exposure was investigated at several temperatures. Springtails showed a significant improvement in survival at temperatures fluctuating between +1 degrees C and -1 degrees C in 12:12-h cycles, and at a constant -3 degrees C, at the highest pyrene concentration (300 mg/kg), while survival remained the same at all temperatures when springtails were exposed to lower pyrene concentrations. It is concluded that temperature and water availability are important factors when assessing the springtails' susceptibility to pyrene exposure.
Endogenous synchronous fluorescence spectroscopy (SFS) of basal cell carcinoma-initial study

NASA Astrophysics Data System (ADS)

Borisova, E.; Zhelyazkova, Al.; Keremedchiev, M.; Penkov, N.; Semyachkina-Glushkovskaya, O.; Avramov, L.

2016-01-01

The human skin is a complex, multilayered and inhomogeneous organ with spatially varying optical properties. Analysis of cutaneous fluorescence spectra could be a very complicated task; therefore researchers apply complex mathematical tools for data evaluation, or try to find some specific approaches, that would simplify the spectral analysis. Synchronous fluorescence spectroscopy (SFS) allows improving the spectral resolution, which could be useful for the biological tissue fluorescence characterization and could increase the tumour detection diagnostic accuracy.

Pancreatic tissue assessment using fluorescence and reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Chandra, Malavika; Heidt, David; Simeone, Diane; McKenna, Barbara; Scheiman, James; Mycek, Mary-Ann

2007-07-01

The ability of multi-modal optical spectroscopy to detect signals from pancreatic tissue was demonstrated by studying human pancreatic cancer xenografts in mice and freshly excised human pancreatic tumor tissue. Measured optical spectra and fluorescence decays were correlated with tissue morphological and biochemical properties. The measured spectral features and decay times correlated well with expected pathological differences in normal, pancreatitis and adenocarcinoma tissue states. The observed differences between the fluorescence and reflectance properties of normal, pancreatitis and adenocarcinoma tissue indicate a possible application of multi-modal optical spectroscopy to differentiating between the three tissue classifications.
The modifier effects of chymotrypsin and trypsin enzymes on fluorescence lifetime distribution of "N-(1-pyrenyl)maleimide-bovine serum albumin" complex

NASA Astrophysics Data System (ADS)

Özyiğit, İbrahim Ethem; Karakuş, Emine; Pekcan, Önder

2016-02-01

Chymotrypsin and trypsin are the well known proteolytic enzymes, both of which are synthesized in the pancreas as their precursors - the inactive forms; chymotrypsinogen and trypsinogen - and then are released into the duodenum to cut proteins into smaller peptides. In this paper, the effects of activities of chymotrypsin and trypsin enzymes on fluorescence lifetime distributions of the substrat bovine serum albumin (BSA) modified with N-(1-pyrenyl)maleimide (PM) were examined. In the labeling study of BSA with PM, it is aimed to attach PM to the single free thiol (Cys34) and to all the free amine groups in accessible positions in order to produce excimers of pyrene planes of the possible highest amount to form the lifetime distributions in the widest range, that may show specifically distinguishing changes resulting from the activities of the proteases. The time resolved spectrofluorometer was used to monitor fluorescence decays, which were analyzed by using the exponential series method (ESM) to obtain the changes of lifetime distributions. After the exposure of the synthesized substrat PM-BSA to the enzymes, the fluorescence lifetime distributions exhibited different structures which were attributed to the different activities of the proteases.
Fluorescence spectroscopy and confocal microscopy of the mycotoxin citrinin in condensed phase and hydrogel films.

PubMed

Lauer, Milena H; Gehlen, Marcelo H; de Jesus, Karen; Berlinck, Roberto G S

2014-05-01

The emission spectra, quantum yields and fluorescence lifetimes of citrinin in organic solvents and hydrogel films have been determined. Citrinin shows complex fluorescence decays due to the presence of two tautomers in solution and interconversion from excited-state double proton transfer (ESDPT) process. The fluorescence decay times associated with the two tautomers have values near 1 and 5 ns depending on the medium. In hydrogel films of agarose and alginate, fluorescence imaging showed that citrinin is not homogeneously dispersed and highly emissive micrometer spots may be formed. Fluorescence spectrum and decay analysis are used to recognize the presence of citrinin in hydrogel films using confocal fluorescence microscopy and spectroscopy.
Quantitative analysis of essential oils of Thymus daenensis using laser-induced fluorescence and Raman spectroscopy.

PubMed

Khoshroo, H; Khadem, H; Bahreini, M; Tavassoli, S H; Hadian, J

2015-11-10

Laser-induced fluorescence and Raman spectroscopy are used for the investigation of different genotypes of Thymus daenensis native to the Ilam province of Iran. Different genotypes of T. daenensis essential oils, labeled T1 through T7, possess slight differences with regard to the composition of the thymol. The gas chromatography-mass spectrometry (GC-MS) method is performed to determine the concentration of each constituent as a reference method. The Raman spectra of different concentrations of pure thymol dissolved in hexane as standard samples are obtained via a laboratory prototype Raman spectroscopy setup for the calculation of the calibration curve. The regression coefficient and limit of detection are calculated. The possibility of the differentiation of different genotypes of T. daenensis is also examined by laser-induced fluorescence spectroscopy, although we do not know the exact amounts of their components. All the fluorescence spectral information is used jointly by cluster analysis to differentiate between 7 genotypes. Our results demonstrate the acceptable precision of Raman spectroscopy with GC-MS and corroborate the capacity of Raman spectroscopy in applications in the quantitative analysis field. Furthermore, the cluster analysis results show that laser-induced fluorescence spectroscopy is an acceptable technique for the rapid classification of different genotypes of T. daenensis without having any previous information of their exact amount of constituents. So, the ability to rapidly and nondestructively differentiate between genotypes makes it possible to efficiently select high-quality herbs from many samples.
Modulated Raman Spectroscopy for Enhanced Cancer Diagnosis at the Cellular Level

PubMed Central

De Luca, Anna Chiara; Dholakia, Kishan; Mazilu, Michael

2015-01-01

Raman spectroscopy is emerging as a promising and novel biophotonics tool for non-invasive, real-time diagnosis of tissue and cell abnormalities. However, the presence of a strong fluorescence background is a key issue that can detract from the use of Raman spectroscopy in routine clinical care. The review summarizes the state-of-the-art methods to remove the fluorescence background and explores recent achievements to address this issue obtained with modulated Raman spectroscopy. This innovative approach can be used to extract the Raman spectral component from the fluorescence background and improve the quality of the Raman signal. We describe the potential of modulated Raman spectroscopy as a rapid, inexpensive and accurate clinical tool to detect the presence of bladder cancer cells. Finally, in a broader context, we show how this approach can greatly enhance the sensitivity of integrated Raman spectroscopy and microfluidic systems, opening new prospects for portable higher throughput Raman cell sorting. PMID:26110401
Spectroscopic techniques to study the immune response in human saliva

NASA Astrophysics Data System (ADS)

Nepomnyashchaya, E.; Savchenko, E.; Velichko, E.; Bogomaz, T.; Aksenov, E.

2018-01-01

Studies of the immune response dynamics by means of spectroscopic techniques, i.e., laser correlation spectroscopy and fluorescence spectroscopy, are described. The laser correlation spectroscopy is aimed at measuring sizes of particles in biological fluids. The fluorescence spectroscopy allows studying of the conformational and other structural changings in immune complex. We have developed a new scheme of a laser correlation spectrometer and an original signal processing algorithm. We have suggested a new fluorescence detection scheme based on a prism and an integrating pin diode. The developed system based on the spectroscopic techniques allows studies of complex process in human saliva and opens some prospects for an individual treatment of immune diseases.
[Rapid identification of hogwash oil by using synchronous fluorescence spectroscopy].

PubMed

Sun, Yan-Hui; An, Hai-Yang; Jia, Xiao-Li; Wang, Juan

2012-10-01

To identify hogwash oil quickly, the characteristic delta lambda of hogwash oil was analyzed by three dimensional fluorescence spectroscopy with parallel factor analysis, and the model was built up by using synchronous fluorescence spectroscopy with support vector machines (SVM). The results showed that the characteristic delta lambda of hogwash oil was 60 nm. Collecting original spectrum of different samples under the condition of characteristic delta lambda 60 nm, the best model was established while 5 principal components were selected from original spectrum and the radial basis function (RBF) was used as the kernel function, and the optimal penalty factor C and kernel function g were 512 and 0.5 respectively obtained by the grid searching and 6-fold cross validation. The discrimination rate of the model was 100% for both training sets and prediction sets. Thus, it is quick and accurate to apply synchronous fluorescence spectroscopy to identification of hogwash oil.
Hydrogen bonding-assisted interaction between amitriptyline hydrochloride and hemoglobin: spectroscopic and molecular dynamics studies.

PubMed

Maurya, Neha; Maurya, Jitendra Kumar; Kumari, Meena; Khan, Abbul Bashar; Dohare, Ravins; Patel, Rajan

2017-05-01

Herein, we have explored the interaction between amitriptyline hydrochloride (AMT) and hemoglobin (Hb), using steady-state and time-resolved fluorescence spectroscopy, UV-visible spectroscopy, and circular dichroism spectroscopy, in combination with molecular docking and molecular dynamic (MD) simulation methods. The steady-state fluorescence reveals the static quenching mechanism in the interaction system, which was further confirmed by UV-visible and time-resolved fluorescence spectroscopy. The binding constant, number of binding sites, and thermodynamic parameters viz. ΔG, ΔH, ΔS are also considered; result confirms that the binding of the AMT with Hb is a spontaneous process, involving hydrogen bonding and van der Waals interactions with a single binding site, as also confirmed by molecular docking study. Synchronous fluorescence, CD data, and MD simulation results contribute toward understanding the effect of AMT on Hb to interpret the conformational change in Hb upon binding in aqueous solution.
Chemometric classification of Chinese lager beers according to manufacturer based on data fusion of fluorescence, UV and visible spectroscopies.

PubMed

Tan, Jin; Li, Rong; Jiang, Zi-Tao

2015-10-01

We report an application of data fusion for chemometric classification of 135 canned samples of Chinese lager beers by manufacturer based on the combination of fluorescence, UV and visible spectroscopies. Right-angle synchronous fluorescence spectra (SFS) at three wavelength difference Δλ=30, 60 and 80 nm and visible spectra in the range 380-700 nm of undiluted beers were recorded. UV spectra in the range 240-400 nm of diluted beers were measured. A classification model was built using principal component analysis (PCA) and linear discriminant analysis (LDA). LDA with cross-validation showed that the data fusion could achieve 78.5-86.7% correct classification (sensitivity), while those rates using individual spectroscopies ranged from 42.2% to 70.4%. The results demonstrated that the fluorescence, UV and visible spectroscopies complemented each other, yielding higher synergic effect. Copyright © 2015 Elsevier Ltd. All rights reserved.
Shifts due to quantum-mechanical interference from distant neighboring resonances for saturated fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Marsman, Alain; Horbatsch, Marko; Hessels, Eric A.

2014-05-01

Quantum-mechanical interference with distant neighboring resonances is found to cause shifts for precision saturated fluorescence spectroscopy of the atomic helium 23 S -to- 23 P transitions. The shifts are significant (larger than the experimental uncertainties for measurements of the intervals) despite the fact that the neighboring resonances are separated from the measured resonances by 1400 and 20 000 natural widths. The shifts depend strongly on experimental parameters such as the angular position of the fluorescence detector and the intensity and size of laser beams. These shifts must be considered for the ongoing program of determining the fine-structure constant from the helium 23 P fine structure. The work represents the first study of such interference shifts for saturated fluorescence spectroscopy and follows up on our previous study of similar shifts for laser spectroscopy. This work is supported by NSERC, CRC, ORF, CFI, NIST and SHARCNET.
Study on discrimination of oral cancer from normal using blood plasma based on fluorescence steady and excited state at excitation wavelength 280 nm

NASA Astrophysics Data System (ADS)

Rekha, Pachaiappan; Aruna, Prakasa Rao; Ganesan, Singaravelu

2016-03-01

Many research works based on fluorescence spectroscopy have proven its potential in the diagnosis of various diseases using the spectral signatures of the native key fluorophores such as tryptophan, tyrosine, collagen, NADH, FAD and porphyrin. These fluorophores distribution, concentration and their conformation may be changed depending upon the pathological and metabolic conditions of cells and tissues. In this study, we have made an attempt to characterize the blood plasma of normal subject and oral cancer patients by native fluorescence spectroscopy at 280 nm excitation. Further, the fluorescence data were analyzed by employing the multivariate statistical method - linear discriminant analyses (LDA) using leaves one out cross validation method. The results illustrate the potential of fluorescence spectroscopy technique in the diagnosis of oral cancer using blood plasma.
Long term trends in atmospheric concentrations of polycyclic aromatic hydrocarbons and nitropolycyclic aromatic hydrocarbons: A study of Japanese cities from 1997 to 2014.

PubMed

Hayakawa, Kazuichi; Tang, Ning; Nagato, Edward Gou; Toriba, Akira; Sakai, Shigekatsu; Kano, Fumio; Goto, Sumio; Endo, Osamu; Arashidani, Kei-Ichi; Kakimoto, Hitoshi

2018-02-01

Total suspended particulate matter (TSP) was collected during the summer and winter in five Japanese cities spanning Hokkaido to Kyushu (Sapporo, Kanazawa, Tokyo, Sagamihara and Kitakyushu) from 1997 to 2014. Nine polycyclic aromatic hydrocarbons (PAHs) with four to six rings, including pyrene (Pyr) and benzo[a]pyrene (BaP), were identified using high-performance liquid chromatography (HPLC) with fluorescence detection. Two nitropolycyclic aromatic hydrocarbons (NPAHs), 1-nitropyrene (1-NP) and 6-nitrobenzo[a]pyrene (6-NBaP), were identified by HPLC with chemiluminescence detection. A comparison of PAH and NPAH concentrations and [NPAH]/[PAH] ratios such as [1-NP]/[Pyr] and [6-NBaP]/[BaP] revealed the following characteristics in the five cities: (1) In Sapporo, Kanazawa, Tokyo and Sagamihara, the concentrations of PAHs and NPAHs were high at the beginning of the sampling period and then steadily decreased, with NPAHs decreasing faster than PAHs. The large initial [1-NP]/[Pyr] ratios suggest that the major contributor was automobiles but subsequent decreases in this ratio suggest decreased automobile contributions. (2) By contrast, PAH concentrations in Kitakyushu did not decrease during the sampling period, though concentrations of NPAHs decreased. The consistently smaller [1-NP]/[Pyr] ratio and larger [6-NBaP]/[BaP] ratio in Kitakyushu suggests that the major contributor of PAHs was not automobiles but iron manufacturing which uses a large amount of coal. The sudden increase in atmospheric PAH concentrations in the winter of 2014 may also be due to iron manufacturing. Copyright © 2017 Elsevier Ltd. All rights reserved.
Flow-directed loading of block copolymer micelles with hydrophobic probes in a gas-liquid microreactor.

PubMed

Wang, Chih-Wei; Bains, Aman; Sinton, David; Moffitt, Matthew G

2013-07-02

We investigate the loading efficiencies of two chemically distinct hydrophobic fluorescent probes, pyrene and naphthalene, for self-assembly and loading of polystyrene-block-poly(acrylic acid) (PS-b-PAA) micelles in gas-liquid segmented microfluidic reactors under different chemical and flow conditions. On-chip loading efficiencies are compared to values obtained via off-chip dropwise water addition to a solution of copolymer and probe. On-chip, probe loading efficiencies depend strongly on the chemical probe, initial solvent, water content, and flow rate. For pyrene and naphthalene probes, maximum on-chip loading efficiencies of 73 ± 6% and 11 ± 3%, respectively, are obtained, in both cases using the more polar solvent (DMF), an intermediate water content (2 wt % above critical), and a low flow rate (∼5 μL/min); these values are compared to 81 ± 6% and 48 ± 2%, respectively, for off-chip loading. On-chip loading shows a significant improvement over the off-chip process where shear-induced formation of smaller micelles enables increased encapsulation of probe. As well, we show that on-chip loading allows off-chip release kinetics to be controlled via flow rate: compared to vehicles produced at ∼5 μL/min, pyrene release kinetics from vehicles produced at ∼50 μL/min showed a longer initial period of burst release, followed by slow release over a longer total period. These results demonstrate the necessity to match probes, solvents, and running conditions to achieve effective loading, which is essential information for further developing these on-chip platforms for manufacturing drug delivery formulations.
Atmospheric behaviors of polycyclic aromatic hydrocarbons at a Japanese remote background site, Noto peninsula, from 2004 to 2014

NASA Astrophysics Data System (ADS)

Tang, Ning; Hakamata, Mariko; Sato, Kousuke; Okada, Yumi; Yang, Xiaoyang; Tatematsu, Michiya; Toriba, Akira; Kameda, Takayuki; Hayakawa, Kazuichi

2015-11-01

Total suspended particulates were collected at a Japanese remote background site (Noto Air Monitoring Station; NAMS) on the Noto Peninsula from September 2004 to June 2014. Nine polycyclic aromatic hydrocarbons (PAHs) in the particulates (fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, benzo[ghi]perylene and indeno[1,2,3-cd]pyrene) were determined by HPLC with fluorescence detection. The mean total concentrations of the nine PAHs in the cold season (November to May for the years 2004-2014) was 670 pg m-3 (range 37-4100 pg m-3). The mean total concentration in the warm season (June to October for the same period) was 170 pg m-3 (range 31-960 pg m-3). The atmospheric PAH level at NAMS decreased in recent years, although no significant change was found in the warm season. An analysis of meteorological conditions showed that the atmospheric PAHs at NAMS were long range transported from Northeast China in the cold seasons and were contributed to by Japanese domestic sources in the warm seasons. Lower concentration ratios of reactive PAHs to their isomers at NAMS also supported these results. Activities associated with the Beijing Olympic and Paralympic Games in 2008 and reconstruction after the 2007 Noto Hanto earthquake may have contributed to the yearly variations of atmospheric PAH levels at NAMS during the period 2007-2009. Source control measures implemented by the Chinese and Japanese governments appear to have been effective in decreasing the atmospheric PAH levels at NAMS in recent years.
[Immobilization of introduced bacteria and degradation of pyrene and benzo(alpha) pyrene in soil by immobilized bacteria].

PubMed

Wang, Xin; Li, Peijun; Song, Shouzhi; Zhong, Yong; Zhang, Hui; Verkhozina, E V

2006-11-01

In this study, introduced bacteria were applied in the bioremediation of pyrene and benzo (alpha) pyrene in organic pollutants-contaminated soils, aimed to test whether it was feasible to introduce bacteria to environmental engineering. Three introduced bacteria were immobilized separately or together to degrade the pyrene and benzo (alpha) pyrene in soil, taking dissociated bacteria as the control, and comparing with three indigenous bacteria. The results showed that immobilized introduced bacteria, either single or mixed, had higher degradation efficiency than dissociated bacteria. Compared with indigenous bacteria, some introduced bacteria had predominance to some degree. The introduced bacteria-mixture had better degradation efficiency after being immobilized. The degradation rate of pyrene and benzo(alpha) pyrene after treated with immobilized bacteria-( B61-B67)-mixture for 96 hours was 43.49% and 38.55%, respectively.
Native fluorescence spectroscopy of blood plasma of rats with experimental diabetes: identifying fingerprints of glucose-related metabolic pathways

NASA Astrophysics Data System (ADS)

Shirshin, Evgeny; Cherkasova, Olga; Tikhonova, Tatiana; Berlovskaya, Elena; Priezzhev, Alexander; Fadeev, Victor

2015-05-01

We present the results of a native fluorescence spectroscopy study of blood plasma of rats with experimental diabetes. It was shown that the fluorescence emission band shape at 320 nm excitation is the most indicative of hyperglycemia in the blood plasma samples. We provide the interpretation of this fact based on the changes in reduced nicotinamide adenine dinucleotide phosphate concentration due to glucose-related metabolic pathways and protein fluorescent cross-linking formation following nonenzymatic glycation.
Fluorescence spectroscopy for the detection of potentially malignant disorders and squamous cell carcinoma of the oral cavity.

PubMed

Francisco, Ana Lucia Noronha; Correr, Wagner Rafael; Azevedo, Luciane Hiramatsu; Kern, Vivian Galletta; Pinto, Clóvis Antônio Lopes; Kowalski, Luiz Paulo; Kurachi, Cristina

2014-06-01

Oral cancer is a public health problem with relevant incidence in the world population. The affected patient usually presents advanced stage disease and the consequence of this delay is a reduction in survival rates. Given this, it is essential to detect oral cancer at early stages. Fluorescence spectroscopy is a non-invasive diagnostic tool that can improve cancer detection in real time. It is a fast and accurate technique, relatively simple, which evaluates the biochemical composition and structure using the tissue fluorescence spectrum as interrogation data. Several studies have positive data regarding the tools for differentiating between normal mucosa and cancer, but the difference between cancer and potentially malignant disorders is not clear. The aim of this study was to evaluate the efficacy of fluorescence spectroscopy in the discrimination of normal oral mucosa, oral cancer, and potentially malignant disorders. The fluorescence spectroscopy was evaluated in 115 individuals, of whom 55 patients presented oral squamous cell carcinoma, 30 volunteers showing normal oral mucosa, and 30 patients having potentially malignant disorders. The spectra were classified and compared to histopathology to evaluate the efficiency in diagnostic discrimination employing fluorescence. In order to classify the spectra, a decision tree algorithm (C4.5) was applied. Despite of the high variance observed in spectral data, the specificity and sensitivity obtained were 93.8% and 88.5%, respectively at 406 nm excitation. These results point to the potential use of fluorescence spectroscopy as an important tool for oral cancer diagnosis and potentially malignant disorders. Copyright © 2014 Elsevier B.V. All rights reserved.
Fluorescent Sensing of Fluoride in Cellular System

PubMed Central

Jiao, Yang; Zhu, Baocun; Chen, Jihua; Duan, Xiaohong

2015-01-01

Fluoride ions have the important roles in a lot of physiological activities related with biological and medical system, such as water fluoridation, caries treatment, and bone disease treatment. Great efforts have been made to develop new methods and strategies for F- detection in the past decades. Traditional methods for the detection of F- including ion chromatography, ion-selective electrodes, and spectroscopic techniques have the limitations in the biomedicine research. The fluorescent probes for F- are very promising that overcome some drawbacks of traditional fluoride detection methods. These probes exhibit high selectivity, high sensitivity as well as quick response to the detection of fluoride anions. The review commences with a brief description of photophysical mechanisms for fluorescent probes for fluoride, including photo induced electron transfer (PET), intramolecular charge transfer (ICT), fluorescence resonance energy transfer (FRET), and excited-state intramolecular proton transfer (ESIPT). Followed by a discussion about common dyes for fluorescent fluoride probes, such as anthracene, naphalimide, pyrene, BODIPY, fluorescein, rhodamine, resorufin, coumarin, cyanine, and near-infrared (NIR) dyes. We divide the fluorescent probes for fluoride in cellular application systems into nine groups, for example, type of hydrogen bonds, type of cleavage of Si-O bonds, type of Si-O bond cleavage and cylization reactions, etc. We also review the recent reported carriers in the delivery of fluorescent fluoride probes. Seventy-four typical fluorescent fluoride probes are listed and compared in detail, including quantum yield, reaction medium, excitation and emission wavelengths, linear detection range, selectivity for F-, mechanism, and analytical applications. Finally, we discuss the future challenges of the application of fluorescent fluoride probes in cellular system and in vivo. We wish that more and more excellent fluorescent fluoride probes will be developed and applied in the biomedicine field in the future. PMID:25553106
Fluorescence suppression using wavelength modulated Raman spectroscopy in fiber-probe-based tissue analysis.

PubMed

Praveen, Bavishna B; Ashok, Praveen C; Mazilu, Michael; Riches, Andrew; Herrington, Simon; Dholakia, Kishan

2012-07-01

In the field of biomedical optics, Raman spectroscopy is a powerful tool for probing the chemical composition of biological samples. In particular, fiber Raman probes play a crucial role for in vivo and ex vivo tissue analysis. However, the high-fluorescence background typically contributed by the auto fluorescence from both a tissue sample and the fiber-probe interferes strongly with the relatively weak Raman signal. Here we demonstrate the implementation of wavelength-modulated Raman spectroscopy (WMRS) to suppress the fluorescence background while analyzing tissues using fiber Raman probes. We have observed a significant signal-to-noise ratio enhancement in the Raman bands of bone tissue, which have a relatively high fluorescence background. Implementation of WMRS in fiber-probe-based bone tissue study yielded usable Raman spectra in a relatively short acquisition time (∼30 s), notably without any special sample preparation stage. Finally, we have validated its capability to suppress fluorescence on other tissue samples such as adipose tissue derived from four different species.
Cholesterol-conjugated supramolecular assemblies of low generations polyamidoamine dendrimers for enhanced EGFP plasmid DNA transfection

NASA Astrophysics Data System (ADS)

Golkar, Nasim; Samani, Soliman Mohammadi; Tamaddon, Ali Mohammad

2016-05-01

Aimed to prepare an enhanced gene delivery system with low cytotoxicity and high transfection efficiency, various cholesterol-conjugated derivates of low generation polyamidoamine (PAMAM) dendrimers were prepared. The conjugates were characterized by TNBS assay, FTIR, and 1H-NMR spectroscopy. Self-assembly of the dendrimer conjugates (G1-Chol, G2-Chol, and G3-Chol) was investigated by pyrene assay. Following formation of the complexes between enhanced green fluorescence protein plasmid and the dendrimer conjugates at various N (primary amine)/P (phosphate) mole ratios, plasmid condensation, biologic stability, cytotoxicity, and protein expression were investigated. The conjugates self-assembled into micellar dispersions with the critical micelle concentration values (<50 µg/ml) depending on the dendrimer generation and cholesterol/amine mole ratio. Cholesterol conjugation resulted in higher resistance of the condensed plasmid DNA in a competition assay with heparin sulfate. Also, the transfection efficiency was determined higher for the cholesterol conjugates than unmodified dendrimers in HepG2 cells, showing the highest for G2-Chol at 40 % degree of cholesterol modification (G2-Chol40 %) among various dendrimer generations. Interestingly, such conjugate showed a complete protection of plasmid against serum nucleases. Our results confirmed that the cholesterol conjugation to PAMAM dendrimers of low generations bearing little cytotoxicity improves their several physicochemical and biological characteristics required for an enhanced delivery of plasmid DNA into cells.

Nanostructured DPA-MPC-DPA triblock copolymer gel for controlled drug release of ketoprofen and spironolactone.

PubMed

Azmy, Bahaa; Standen, Guy; Kristova, Petra; Flint, Andrew; Lewis, Andrew L; Salvage, Jonathan P

2017-08-01

Uncontrolled rapid release of drugs can reduce their therapeutic efficacy and cause undesirable toxicity; however, controlled release from reservoir materials helps overcome this issue. The aims of this study were to determine the release profiles of ketoprofen and spironolactone from a pH-responsive self-assembling DPA-MPC-DPA triblock copolymer gel and elucidate underlying physiochemical properties. Drug release profiles from DPA 50 -MPC 250 -DPA 50 gel (pH 7.5), over 32 h (37 °C), were determined using UV-Vis spectroscopy. Nanoparticle size was measured by dynamic light scattering (DLS) and critical micelle concentration (CMC) by pyrene fluorescence. Polymer gel viscosity was examined via rheology, nanoparticle morphology investigated using scanning transmission electron microscopy (STEM) and the gel matrix observed using cryo-scanning electron microscopy (Cryo-SEM). DPA 50 -MPC 250 -DPA 50 copolymer (15% w/v) formed a free-standing gel (pH 7.5) that controlled drug release relative to free drugs. The copolymer possessed a low CMC, nanoparticle size increased with copolymer concentration, and DLS data were consistent with STEM. The gel displayed thermostable viscosity at physiological temperatures, and the gel matrix was a nanostructured aggregation of smaller nanoparticles. The DPA 50 -MPC 250 -DPA 50 copolymer gel could be used as a drug delivery system to provide the controlled drug release of ketoprofen and spironolactone. © 2017 Royal Pharmaceutical Society.
Rapid detection of bacterial pathogens using flourescence spectroscopy and chemometrics

USDA-ARS?s Scientific Manuscript database

This work presents the development of a method for rapid bacterial identification based on the fluorescence spectroscopy combined with multivariate analysis. Fluorescence spectra of pure three different genera of bacteria (Escherichia coli, Salmonella, and Campylobacter) were collected from 200...
Bespoke contrast-matched diblock copolymer nanoparticles enable the rational design of highly transparent Pickering double emulsions

NASA Astrophysics Data System (ADS)

Rymaruk, Matthew J.; Thompson, Kate L.; Derry, Matthew J.; Warren, Nicholas J.; Ratcliffe, Liam P. D.; Williams, Clive N.; Brown, Steven L.; Armes, Steven P.

2016-07-01

We report the preparation of highly transparent oil-in-water Pickering emulsions using contrast-matched organic nanoparticles. This is achieved via addition of judicious amounts of either sucrose or glycerol to an aqueous dispersion of poly(glycerol monomethacrylate)56-poly(2,2,2-trifluoroethyl methacrylate)500 [PGMA-PTFEMA] diblock copolymer nanoparticles prior to high shear homogenization with an equal volume of n-dodecane. The resulting Pickering emulsions comprise polydisperse n-dodecane droplets of 20-100 μm diameter and exhibit up to 96% transmittance across the visible spectrum. In contrast, control experiments using non-contrast-matched poly(glycerol monomethacrylate)56-poly(benzyl methacrylate)300 [PGMA56-PBzMA300] diblock copolymer nanoparticles as a Pickering emulsifier only produced conventional highly turbid emulsions. Thus contrast-matching of the two immiscible phases is a necessary but not sufficient condition for the preparation of highly transparent Pickering emulsions: it is essential to use isorefractive nanoparticles in order to minimize light scattering. Furthermore, highly transparent oil-in-water-in-oil Pickering double emulsions can be obtained by homogenizing the contrast-matched oil-in-water Pickering emulsion prepared using the PGMA56-PTFEMA500 nanoparticles with a contrast-matched dispersion of hydrophobic poly(lauryl methacrylate)39-poly(2,2,2-trifluoroethyl methacrylate)800 [PLMA39-PTFEMA800] diblock copolymer nanoparticles in n-dodecane. Finally, we show that an isorefractive oil-in-water Pickering emulsion enables fluorescence spectroscopy to be used to monitor the transport of water-insoluble small molecules (pyrene and benzophenone) between n-dodecane droplets. Such transport is significantly less efficient than that observed for the equivalent isorefractive surfactant-stabilized emulsion. Conventional turbid emulsions do not enable such a comparison to be made because the intense light scattering leads to substantial spectral attenuation.We report the preparation of highly transparent oil-in-water Pickering emulsions using contrast-matched organic nanoparticles. This is achieved via addition of judicious amounts of either sucrose or glycerol to an aqueous dispersion of poly(glycerol monomethacrylate)56-poly(2,2,2-trifluoroethyl methacrylate)500 [PGMA-PTFEMA] diblock copolymer nanoparticles prior to high shear homogenization with an equal volume of n-dodecane. The resulting Pickering emulsions comprise polydisperse n-dodecane droplets of 20-100 μm diameter and exhibit up to 96% transmittance across the visible spectrum. In contrast, control experiments using non-contrast-matched poly(glycerol monomethacrylate)56-poly(benzyl methacrylate)300 [PGMA56-PBzMA300] diblock copolymer nanoparticles as a Pickering emulsifier only produced conventional highly turbid emulsions. Thus contrast-matching of the two immiscible phases is a necessary but not sufficient condition for the preparation of highly transparent Pickering emulsions: it is essential to use isorefractive nanoparticles in order to minimize light scattering. Furthermore, highly transparent oil-in-water-in-oil Pickering double emulsions can be obtained by homogenizing the contrast-matched oil-in-water Pickering emulsion prepared using the PGMA56-PTFEMA500 nanoparticles with a contrast-matched dispersion of hydrophobic poly(lauryl methacrylate)39-poly(2,2,2-trifluoroethyl methacrylate)800 [PLMA39-PTFEMA800] diblock copolymer nanoparticles in n-dodecane. Finally, we show that an isorefractive oil-in-water Pickering emulsion enables fluorescence spectroscopy to be used to monitor the transport of water-insoluble small molecules (pyrene and benzophenone) between n-dodecane droplets. Such transport is significantly less efficient than that observed for the equivalent isorefractive surfactant-stabilized emulsion. Conventional turbid emulsions do not enable such a comparison to be made because the intense light scattering leads to substantial spectral attenuation. Electronic supplementary information (ESI) available: GPC chromatograms, additional transmission electron micrographs, digital photographs, visible absorption spectra and laser diffraction data, further optical and fluorescence micrographs. See DOI: 10.1039/c6nr03856e
Laser-induced fluorescence spectroscopy in tissue local necrosis detection

NASA Astrophysics Data System (ADS)

Cip, Ondrej; Buchta, Zdenek; Lesundak, Adam; Randula, Antonin; Mikel, Bretislav; Lazar, Josef; Veverkova, Lenka

2014-03-01

The recent effort leads to reliable imaging techniques which can help to a surgeon during operations. The fluorescence spectroscopy was selected as very useful online in vivo imaging method to organics and biological materials analysis. The presented work scopes to a laser induced fluorescence spectroscopy technique to detect tissue local necrosis in small intestine surgery. In first experiments, we tested tissue auto-fluorescence technique but a signal-to-noise ratio didn't express significant results. Then we applied a contrast dye - IndoCyanine Green (ICG) which absorbs and emits wavelengths in the near IR. We arranged the pilot experimental setup based on highly coherent extended cavity diode laser (ECDL) used for stimulating of some critical areas of the small intestine tissue with injected ICG dye. We demonstrated the distribution of the ICG exciter with the first file of shots of small intestine tissue of a rabbit that was captured by high sensitivity fluorescent cam.
Interaction of sodium benzoate with trypsin by spectroscopic techniques

NASA Astrophysics Data System (ADS)

Mu, Yue; Lin, Jing; Liu, Rutao

2011-12-01

The toxicity of sodium benzoate to trypsin was investigated by fluorescence spectroscopy, synchronous fluorescence spectroscopy, UV-visible absorption spectroscopy and circular dichroism (CD) spectroscopy under mimic physiological conditions. Sodium benzoate could unfold trypsin by decreasing the β-sheet structure, which leads to more exposure of internal amino acid groups and the obvious intrinsic fluorescence quenching with the rising concentration of sodium benzoate. The results of spectroscopic measurements indicated that sodium benzoate changed the internal microenvironment of trypsin and induced the alteration of the whole molecule, which were performed toxic effects on the organism. Trypsin and sodium benzoate interacted with each other to produce a substance by van der Waals forces and hydrogen bond, the model of which was shown by AutoDock software.
Fluorescent quantification of melanin.

PubMed

Fernandes, Bruno; Matamá, Teresa; Guimarães, Diana; Gomes, Andreia; Cavaco-Paulo, Artur

2016-11-01

Melanin quantification is reportedly performed by absorption spectroscopy, commonly at 405 nm. Here, we propose the implementation of fluorescence spectroscopy for melanin assessment. In a typical in vitro assay to assess melanin production in response to an external stimulus, absorption spectroscopy clearly overvalues melanin content. This method is also incapable of distinguishing non-melanotic/amelanotic control cells from those that are actually capable of performing melanogenesis. Therefore, fluorescence spectroscopy is the best method for melanin quantification as it proved to be highly specific and accurate, detecting even small variations in the synthesis of melanin. This method can also be applied to the quantification of melanin in more complex biological matrices like zebrafish embryos and human hair. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Spectroscopy detection of green and red fluorescent proteins in genetically modified plants using a fiber optics system

NASA Astrophysics Data System (ADS)

Liew, Oi Wah; Asundi, Anand K.; Chen, Jun-Wei; Chew, Yiwen; Yu, Shangjuan; Yeo, Gare H.

2001-05-01

In this paper, fiber optic spectroscopy is developed to detect and quantify recombinant green (EGFP) and red (DsRED) fluorescent proteins in vitro and in vivo. The bacterial expression vectors carrying the coding regions of EGFP and DsRED were introduced into Escherichia coli host cells and fluorescent proteins were produced following induction with IPTG. Soluble EGFP and DsRED proteins were isolated from lysed bacterial cells and serially diluted for quantitative analysis by fiber optic spectroscopy. Fluorescence at the appropriate emission wavelengths could be detected up to 64X dilution for EGFP and 40X dilution for DsRED. To determine the capability of spectroscopy detection in vivo, transgenic potato hairy roots expressing EGFP and DsRED were regenerated. This was achieved by cloning the EGFP and DsRED genes into the plant binary vector, pTMV35S, to create the recombinant vectors pGLOWGreen and pGLOWRed. These latter binary vectors were introduced into Agrobacterium rhizogenes strain A4T. Infection of potato cells with transformed agrobacteria was used to insert the fluorescent protein genes into the potato genome. Genetically modified potato cells were then regenerated into hairy roots. A panel of transformed hairy roots expressing varying levels of fluorescent proteins was selected by fluorescence microscopy. We are now assessing the capability of spectroscopic detection system for in vivo quantification of green and red fluorescence levels in transformed roots.
Effects of shape, size, and pyrene doping on electronic properties of graphene nanoflakes.

PubMed

Kuamit, Thanawit; Ratanasak, Manussada; Rungnim, Chompoonut; Parasuk, Vudhichai

2017-11-25

Effects of size, shape, and pyrene doping on electronic properties of graphene nanoflakes (GNFs) were theoretically investigated using density functional theory method with PBE, B3PW91, and M06-2X functionals and cc-pVDZ basis set. Two shapes of zigzag GNFs, hexagonal (HGN) and rhomboidal (RGN), were considered. The energy band gap of GNF depends on shape and decreases with size. The HGN has larger band gap energy (1.23-3.96 eV) than the RGN (0.13-2.12 eV). The doping of pyrene and pyrene derivatives on both HGN and RGN was also studied. The adsorption energy of pyrene and pyrene derivatives on GNF does not depend on the shape of GNFs with energies between 21 and 27 kcal mol -1 . The substituent on pyrene enhances the binding to GNF but the strength does not depend on electron withdrawing or donating capability. The doping by pyrene and pyrene derivatives also shifts the HOMO and LUMO energies of GNFs. Both positive (destabilizing) and negative (stabilizing) shifts on HOMO and LUMO of GNFs were seen. The direction and magnitude of the shift do not follow the electron withdrawing and donating capability of pyrene substituents. However, only a slight shift was observed for doped RGN. A shift of 0.19 eV was noticed for HOMO of HGN doped with 1-aminopyrene (pyNH 2 ) and of 0.04 eV for LUMO of HGN doped with 1-pyrenecarboxylic acid (pyCOOH). Graphical Abstract HOMO and LUMO Energies of pyrene/pyrene derivatives doped Graphene Nanoflakes.
Direct solid surface fluorescence spectroscopy of standard chemicals and humic acid in ternary system

NASA Astrophysics Data System (ADS)

Mounier, S.; Nicolodelli, G.; Redon, R.; Milori, D. M. B. P.

2017-04-01

The front face fluorescence spectroscopy is often used to quantify chemicals in well-known matrices as it is a rapid and powerful technique, with no sample preparation. However it was not used to investigate extracted organic matter like humic substances. This work aims to fully investigate for the first time front face fluorescence spectroscopy response of a ternary system including boric acid, tryptophan and humic substances, and two binaries system containing quinine sulfate or humic substance in boric acid. Pure chemicals, boric acid, tryptophan, quinine sulfate and humic acid were mixed together in solid pellet at different contents from 0 to 100% in mass. The measurement of excitation emission matrix of fluorescence (3D fluorescence) and laser induced fluorescence were then done in the front face mode. Fluorescence matrices were decomposed using the CP/PARAFAC tools after scattering treatments. Results show that for 3D fluorescence there is no specific component for tryptophan and quinine sulfate, and that humic substances lead to a strong extinction effect for mixture containing quinine sulfate. Laser induced fluorescence gives a very good but non-specific related response for both quinine sulfate and tryptophan. No humic substances fluorescence response was found, but extinction effect is observed as for 3D fluorescence. This effect is stronger for quinine sulfate than for tryptophan. These responses were modeled using a simple absorbance versus emission model.
The endophytic bacterium Serratia sp. PW7 degrades pyrene in wheat.

PubMed

Zhu, Xuezhu; Wang, Wanqing; Crowley, David E; Sun, Kai; Hao, Shupeng; Waigi, Michael Gatheru; Gao, Yanzheng

2017-03-01

This research was conducted to isolate polycyclic aromatic hydrocarbon-degrading (PAH-degrading) endophytic bacteria and investigate their potential in protecting plants against PAH contamination. Pyrene-degrading endophytic bacteria were isolated from plants grown in PAH-contaminated soil. Among these endophytic bacteria, strain PW7 (Serratia sp.) isolated from Plantago asiatica was selected to investigate the suppression of pyrene accumulation in Triticum aestivum L. In the in vitro tests, strain PW7 degraded 51.2% of the pyrene in the media within 14 days. The optimal biodegradation conditions were pH 7.0, 30 °C, and MS medium supplemented with additional glucose, maltose, sucrose, and peptones. In the in vivo tests, strain PW7 successfully colonized the roots and shoots of inoculated (E + ) wheat plants, and its colonization decreased pyrene accumulation and pyrene transportation from roots to shoots. Remarkably, the concentration of pyrene in shoots decreased much more than that in roots, suggesting that strain PW7 has the potential for protecting wheat against pyrene contamination and mitigating the threat of pyrene to human health via food consumption.
Effects of alfalfa and organic fertilizer on benzo[a]pyrene dissipation in an aged contaminated soil.

PubMed

Fu, Dengqiang; Teng, Ying; Luo, Yongming; Tu, Chen; Li, Shixing; Li, Zhengao; Christie, Peter

2012-06-01

A climate-controlled pot experiment was conducted to investigate the effects of planting alfalfa and applying organic fertilizer on the dissipation of benzo[a]pyrene from an aged contaminated agricultural soil. Short-term planting of alfalfa inhibited the dissipation of benzo[a]pyrene from the soil by 8.9%, and organic fertilizer enhanced benzo[a]pyrene removal from the soil by 11.6% compared with the unplanted and unfertilized treatments, respectively. No significant interaction was observed between alfalfa and organic fertilizer on benzo[a]pyrene dissipation. Sterilization completely inhibited the removal of benzo[a]pyrene from the soil indicating that its degradation by indigenous microorganisms may have been the main mechanism of dissipation. Furthermore, significant positive relationships were observed between benzo[a]pyrene removal and the contents of soil ammonium nitrogen, nitrate nitrogen, and total mineral nitrogen at the end of the experiment, suggesting that competition between plants and microorganisms for nitrogen may have inhibited benzo[a]pyrene dissipation in the rhizosphere of alfalfa and the addition of organic fertilizer may facilitate microbial degradation of benzo[a]pyrene in the soil.
Ionic calcium determination in skim milk with molecular probes and front-face fluorescence spectroscopy: simple linear regression.

PubMed

Gangidi, R R; Metzger, L E

2006-11-01

The purpose of this study was to determine if the ionic calcium content of skim milk could be determined using molecular probes and front-face fluorescence spectroscopy. Current methods for determining ionic calcium are not sensitive, overestimate ionic calcium, or require complex procedures. Molecular probes designed specifically for measuring ionic calcium could potentially be used to determine the ionic calcium content of skim milk. The goal of the current study was to develop foundation methods for future studies to determine ionic calcium directly in skim milk and other dairy products with molecular probes and fluorescence spectroscopy. In this study, the effect of pH on calcium-sensitive fluorescent probe (Rhod-5N and Fluo-5N) performance using various concentrations of skim milk was determined. The pH of diluted skim milk (1.9 to 8.9% skim milk), was adjusted to either 6.2 or 7.0, after which the samples were analyzed with fluorescent probes (1 microM) and front-face fluorescence spectroscopy. The ionic calcium content of each sample was also determined using a calcium ion-selective electrode. The results demonstrated that the ionic calcium content of each sample was highly correlated (R2 > 0.989) with the fluorescence intensities of the probe-calcium adduct using simple linear regression. Higher than suggested ionic calcium contents of 1,207 and 1,973 microM were determined with the probes (Fluo-5N and Rhod-5N) in diluted skim milk with pH 7.0 and 6.2, respectively. The fluorescence intensity of the probe-calcium adduct decreased with a decrease in pH for the same ionic calcium concentration. This study demonstrates that Fluo-5N and Rhod-5N can be used to determine the ionic-calcium content of diluted milk with front-face fluorescence spectroscopy. Furthermore, these probes may also have the potential to determine the ionic calcium content of undiluted skim milk.
Protein oligomerization monitored by fluorescence fluctuation spectroscopy: Self-assembly of Rubisco activase

USDA-ARS?s Scientific Manuscript database

A methodology is presented to characterize complex protein assembly pathways by fluorescence correlation spectroscopy. We have derived the total autocorrelation function describing the behavior of mixtures of labeled and unlabeled protein under equilibrium conditions. Our modeling approach allows us...
Two-colour dip spectroscopy of jet-cooled molecules

NASA Astrophysics Data System (ADS)

Ito, Mitsuo

In optical-optical double resonance spectroscopy, the resonance transition from an intermediate state to a final state can be detected by a dip of the signal (fluorescence or ion) associated with the intermediate state. This method probing the signal of the intermediate state may be called `two-colour dip spectroscopy'. Various kinds of two-colour dip spectroscopy such as two-colour fluorescence/ion dip spectroscopy, two-colour ionization dip spectroscopy employing stimulated emission, population labelling spectroscopy and mass-selected ion dip spectroscopy with dissociation were briefly described, paying special attention to their characteristics in excitation, detection and application. They were extensively and successfully applied to jet-cooled large molecules and provided us with new useful information on the energy and dynamics of excited molecules.
Detecting Kerogen as a Biosignature Using Co-located UV Time-Gated Raman and Fuorescence Spectroscopy

NASA Astrophysics Data System (ADS)

Shkolyar, S.; Eshelman, E.; Farmer, J. D.; Hamilton, D.; Daly, M. G.; Youngbull, C.

2017-12-01

The Mars 2020 mission will analyze samples in situ and identify any that could have preserved biosignatures in ancient habitable environments for later return to Earth. Highest-priority targeted samples include aqueously formed sedimentary lithologies containing fossil biosignatures as aromatic carbon (kerogen). In this study, we analyze non-extracted, naturally preserved kerogen in a diverse suite of realistic Mars analogs using combined UV excitation time-gated (UV-TG) Raman and laser-induced fluorescence spectroscopy. We interrogated kerogen and its host matrix in samples to: (1) explore the capabilities of UV-TG Raman and fluorescence spectroscopy for detecting kerogen in high-priority targets in the search for a Martian fossil record; (2) assess the effectiveness of time-gating and UV laser wavelength in reducing fluorescence; and (3) identify sample-specific issues which could challenge rover-based identifications of kerogen using UV-TG Raman spectroscopy. We found that ungated UV Raman is suited to identify diagnostic kerogen Raman bands without interfering fluorescence and that fluorescence features indicating kerogen are detectable. These data highlight the value of using both co-located Raman and fluorescence data sets together to strengthen the confidence of kerogen detection as a potential biosignature and are obtainable by SHERLOC onboard Mars 2020.
Fluorescent Gold Nanoclusters for Selective Detection of Dopamine in Cerebrospinal fluid

PubMed Central

Govindaraju, Saravanan; Ankireddy, Seshadri Reddy; Viswanath, Buddolla; Kim, Jongsung; Yun, Kyusik

2017-01-01

Since the last two decades, protein conjugated fluorescent gold nanoclusters (NCs) owe much attention in the field of medical and nanobiotechnology due to their excellent photo stability characteristics. In this paper, we reported stable, nontoxic and red fluorescent emission BSA-Au NCs for selective detection of L-dopamine (DA) in cerebrospinal fluid (CSF). The evolution was probed by various instrumental techniques such as UV-vis spectroscopy, High resolution transmission electron microscopy (HTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL). The synthesised BSA-Au NCs were showing 4–6 nm with high fluorescent ~8% Quantum yield (QY). The fluorescence intensity of BSA-Au NCs was quenched upon the addition of various concentrations of DA via an electron transfer mechanism. The decrease in BSA-Au NCs fluorescence intensity made it possible to determine DA in PBS buffer and the spiked DA in CSF in the linear range from 0 to 10 nM with the limit of detection (LOD) 0.622 and 0.830 nM respectively. Best of our knowledge, as-prepared BSA-Au NCs will gain possible strategy and good platform for biosensor, drug discovery, and rapid disease diagnosis such as Parkinson’s and Alzheimer diseases. PMID:28067307
Characterization of humic acids by two-dimensional correlation fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Nakashima, K.; Xing, Shaoyong; Gong, Yongkuan; Miyajima, Toru

2008-07-01

We have investigated interaction between humic acids and heavy metal ions by fluorescence spectroscopy. The humic acids examined are Aldrich humic acid (AHA) and Dando humic acid (DHA), and heavy metal ions are Cu 2+ and Pb 2+. The binding constants between the humic acids and the heavy metal ions are obtained by a conventional fluorescence quenching technique. The two prominent bands in the fluorescence spectra of the humic acids give different binding constants, implying that the two bands are originated from different fluorescent species in the matrices of the humic acids. This was confirmed by two-dimensional correlation analysis based on the quenching perturbation on the fluorescence spectra. Two prominent cross peaks corresponding to the two fluorescence bands are obtained in the asynchronous maps, indicating that the two fluorescence bands belong to different species. The order of the response of the two fluorescence bands to the quenching perturbation is also elucidated based on Noda's rule.
Mobile humic acids and recalcitrant calcium humate in eight US soils

USDA-ARS?s Scientific Manuscript database

Both excitation-emission matrix (EEM) fluorescence spectroscopy and solid state C-13 nuclear magnetic resonance (NMR) spectroscopy have been applied for studying soil organic matter (SOM), but rarely have both techniques been employed together. We analyzed the fluorescence features of water extracta...
Evaluation of Shifted Excitation Raman Difference Spectroscopy and Comparison to Computational Background Correction Methods Applied to Biochemical Raman Spectra.

PubMed

Cordero, Eliana; Korinth, Florian; Stiebing, Clara; Krafft, Christoph; Schie, Iwan W; Popp, Jürgen

2017-07-27

Raman spectroscopy provides label-free biochemical information from tissue samples without complicated sample preparation. The clinical capability of Raman spectroscopy has been demonstrated in a wide range of in vitro and in vivo applications. However, a challenge for in vivo applications is the simultaneous excitation of auto-fluorescence in the majority of tissues of interest, such as liver, bladder, brain, and others. Raman bands are then superimposed on a fluorescence background, which can be several orders of magnitude larger than the Raman signal. To eliminate the disturbing fluorescence background, several approaches are available. Among instrumentational methods shifted excitation Raman difference spectroscopy (SERDS) has been widely applied and studied. Similarly, computational techniques, for instance extended multiplicative scatter correction (EMSC), have also been employed to remove undesired background contributions. Here, we present a theoretical and experimental evaluation and comparison of fluorescence background removal approaches for Raman spectra based on SERDS and EMSC.
Optimization of Sample Preparation processes of Bone Material for Raman Spectroscopy.

PubMed

Chikhani, Madelen; Wuhrer, Richard; Green, Hayley

2018-03-30

Raman spectroscopy has recently been investigated for use in the calculation of postmortem interval from skeletal material. The fluorescence generated by samples, which affects the interpretation of Raman data, is a major limitation. This study compares the effectiveness of two sample preparation techniques, chemical bleaching and scraping, in the reduction of fluorescence from bone samples during testing with Raman spectroscopy. Visual assessment of Raman spectra obtained at 1064 nm excitation following the preparation protocols indicates an overall reduction in fluorescence. Results demonstrate that scraping is more effective at resolving fluorescence than chemical bleaching. The scraping of skeletonized remains prior to Raman analysis is a less destructive method and allows for the preservation of a bone sample in a state closest to its original form, which is beneficial in forensic investigations. It is recommended that bone scraping supersedes chemical bleaching as the preferred method for sample preparation prior to Raman spectroscopy. © 2018 American Academy of Forensic Sciences.

In Vivo Fluorescence Correlation and Cross-Correlation Spectroscopy

NASA Astrophysics Data System (ADS)

Mütze, Jörg; Ohrt, Thomas; Petrášek, Zdeněk; Schwille, Petra

In this manuscript, we describe the application of Fluorescence Correlation Spectroscopy (FCS), Fluorescence Cross-Correlation Spectroscopy (FCCS), and scanning FCS (sFCS) to two in vivo systems. In the first part, we describe the application of two-photon standard and scanning FCS in Caenorhabditis elegans embryos. The differentiation of a single fertilized egg into a complex organism in C. elegans is regulated by a number of protein-dependent processes. The oocyte divides asymmetrically into two daughter cells of different developmental fate. Two of the involved proteins, PAR-2 and NMY-2, are studied. The second investigated system is the mechanism of RNA interference in human cells. An EGFP based cell line that allows to study the dynamics and localization of the RNA-induced silencing complex (RISC) with FCS in vivo is created, which has so far been inaccessible with other experimental methods. Furthermore, Fluorescence Cross-Correlation Spectroscopy is employed to highlight the asymmetric incorporation of labeled siRNAs into RISC.
Evaluation of Shifted Excitation Raman Difference Spectroscopy and Comparison to Computational Background Correction Methods Applied to Biochemical Raman Spectra

PubMed Central

Cordero, Eliana; Korinth, Florian; Stiebing, Clara; Krafft, Christoph; Schie, Iwan W.; Popp, Jürgen

2017-01-01

Raman spectroscopy provides label-free biochemical information from tissue samples without complicated sample preparation. The clinical capability of Raman spectroscopy has been demonstrated in a wide range of in vitro and in vivo applications. However, a challenge for in vivo applications is the simultaneous excitation of auto-fluorescence in the majority of tissues of interest, such as liver, bladder, brain, and others. Raman bands are then superimposed on a fluorescence background, which can be several orders of magnitude larger than the Raman signal. To eliminate the disturbing fluorescence background, several approaches are available. Among instrumentational methods shifted excitation Raman difference spectroscopy (SERDS) has been widely applied and studied. Similarly, computational techniques, for instance extended multiplicative scatter correction (EMSC), have also been employed to remove undesired background contributions. Here, we present a theoretical and experimental evaluation and comparison of fluorescence background removal approaches for Raman spectra based on SERDS and EMSC. PMID:28749450
Ultraviolet-Visible and Fluorescence Spectroscopy Techniques Are Important Diagnostic Tools during the Progression of Atherosclerosis: Diet Zinc Supplementation Retarded or Delayed Atherosclerosis

PubMed Central

Abdelhalim, Mohamed Anwar K.; Moussa, Sherif A. Abdelmottaleb; AL-Mohy, Yanallah Hussain

2013-01-01

Background. In this study, we examined whether UV-visible and fluorescence spectroscopy techniques detect the progression of atherosclerosis in serum of rabbits fed on high-cholesterol diet (HCD) and HCD supplemented with zinc (HCD + Zn) compared with the control. Methods. The control rabbits group was fed on 100 g/day of normal diet. The HCD group was fed on Purina Certified Rabbit Chow supplemented with 1.0% cholesterol plus 1.0% olive oil (100 g/day) for the same period. The HCD + Zn group was fed on normal Purina Certified Rabbit Chow plus 1.0% cholesterol and 1.0% olive oil supplemented with 470 ppm Zn for the same feeding period. UV-visible and fluorescence spectroscopy and biochemistry in Rabbit's blood serum and blood hematology were measured in Rabbit's blood. Results. We found that the fluorescent peak of HCD shifted toward UV-visible wavelength compared with the control using fluorescent excitation of serum at 192 nm. In addition, they showed that supplementation of zinc (350 ppm) restored the fluorescent peak closely to the control. By using UV-visible spectroscopy approach, we found that the peak absorbance of HCD (about 280 nm) was higher than that of control and that zinc supplementation seemed to decrease the absorbance. Conclusions. This study demonstrates that ultraviolet-visible and fluorescence spectroscopy techniques can be applied as noninvasive techniques on a sample blood serum for diagnosing or detecting the progression of atherosclerosis. The Zn supplementation to rabbits fed on HCD delays or retards the progression of atherosclerosis. Inducing anemia in rabbits fed on HCD delays the progression of atherosclerosis. PMID:24350281
Characterization of particulate polycyclic aromatic hydrocarbons in an urban atmosphere of central-southern Spain.

PubMed

Villanueva, Florentina; Tapia, Araceli; Cabañas, Beatriz; Martínez, Ernesto; Albaladejo, José

2015-12-01

Over 1-year period, 13 polycyclic aromatic hydrocarbons (PAHs) associated with particulate matter PM10 have been monitored for the first time in the atmosphere of Ciudad Real, situated at the central-southern Spain. PM10-bound PAHs were collected using a high-volume sampler from autumn 2012 to summer 2013 and were analyzed by HPLC with fluorescence detector. The most abundant PAHs were pyrene, chrysene, benzo[b]fluoranthene, dibenzo[a,h]anthracene and benzo[g,h,i]perylene. The ∑PAH concentrations in Ciudad Real were 888, 368, 259 and 382 pg m(-3) for winter, spring, summer and autumn seasons, respectively. The diurnal variation of PAH was also investigated presenting the highest concentrations during the evening (19:00-23:00). Benzo[a]pyrene concentrations ranged from 2.4 to 110 pg m(-3), these values are lower than the target value proposed by the European legislation, 1 ng m(-3). Diagnostic ratios were used to identify potential sources of PAHs. Results suggest that vehicle emissions are the major source of identified PAHs, with a higher contribution of diesel engines although other anthropogenic sources could also have an impact on the PAH levels.
Interdependence of pyrene interactions and tetramolecular G4-DNA assembly.

PubMed

Doluca, Osman; Withers, Jamie M; Loo, Trevor S; Edwards, Patrick J B; González, Carlos; Filichev, Vyacheslav V

2015-03-28

Controlling the arrangement of organic chromophores in supramolecular architectures is of primary importance for the development of novel functional molecules. Insertion of a twisted intercalating nucleic acid (TINA) moiety, containing phenylethynylpyren-1-yl derivatives, into a G-rich DNA sequence alters G-quadruplex folding, resulting in supramolecular structures with defined pyrene arrangements. Based on CD, NMR and ESI-mass-spectra, as well as TINA excited dimer (excimer) fluorescence emission we propose that insertion of the TINA monomer in the middle of a dTG4T sequence (i.e. dTGGXGGT, where X is TINA) converts a parallel tetramolecular G-quadruplex into an assembly composed of two identical antiparallel G-quadruplex subunits stacked via TINA-TINA interface. Kinetic analysis showed that TINA-TINA association controls complex formation in the presence of Na(+) but barely competes with guanine-mediated association in K(+) or in the sequence with the longer G-run (dTGGGXGGGT). These results demonstrate new perspectives in the design of molecular entities that can kinetically control G-quadruplex formation and show how tetramolecular G-quadruplexes can be used as a tuneable scaffold to control the arrangement of organic chromophores.
A comparative intracellular proteomic profiling of Pseudomonas aeruginosa strain ASP-53 grown on pyrene or glucose as sole source of carbon and identification of some key enzymes of pyrene biodegradation pathway.

PubMed

Mukherjee, Ashis K; Bhagowati, Pabitra; Biswa, Bhim Bahadur; Chanda, Abhishek; Kalita, Bhargab

2017-09-07

Pseudomonas aeruginosa strain ASP-53, isolated from a petroleum oil-contaminated soil sample, was found to be an efficient degrader of pyrene. PCR amplification of selected hydrocarbon catabolic genes (alkB gene, which encodes for monooxygenase, and the C12O, C23O, and PAH-RHDα genes encoding for the dioxygenase enzyme) from the genomic DNA of P. aeruginosa strain ASP-53 suggested its hydrocarbon degradation potential. The GC-MS analysis demonstrated 30.1% pyrene degradation by P. aeruginosa strain ASP-53 after 144h of incubation at pH6.5, 37°C. Expressions of 115 and 196 intracellular proteins were unambiguously identified and quantitated by shotgun proteomics analysis when the isolate was grown in medium containing pyrene and glucose, respectively. The pyrene-induced uniquely expressed and up-regulated proteins in P. aeruginosa strain ASP-53 in addition to substrate (pyrene) metabolism are also likely to be associated with different cellular functions for example-related to protein folding (molecular chaperone), stress response, metabolism of carbohydrate, proteins and amino acids, and fatty acids; transport of metabolites, energy generation such as ATP synthesis, electron transport and nitrate assimilation, and other oxidation-reduction reactions. Proteomic analyses identified some important enzymes involved in pyrene degradation by P. aeruginosa ASP-53 which shows that this bacterium follows the salicylate pathway of pyrene degradation. This study is the first report on proteomic analysis of pyrene biodegradation pathway by Pseudomonas aeruginosa, isolated from a petroleum-oil contaminated soil sample. The pathway displays partial similarity with deduced pyrene degradation mechanisms of Mycobacterium vanbaalenii PYR-1. The GC-MS analysis as well as PCR amplification of hydrocarbon catabolic genes substantiated the potency of the bacterium under study to effectively degrade high molecular weight, toxic PAH such as pyrene for its filed scale bioremediation experiments. The proteomics approach (LC-MS/MS analysis) identified the differentially regulated intracellular proteins of the isolate P. aeruginosa ASP-53 when grown in pyrene medium. This study identified some important pyrene biodegradation enzymes in Pseudomonas aeruginosa ASP-53 and highlights that the bacterium follows salicylate pathway for pyrene degradation. Copyright © 2017 Elsevier B.V. All rights reserved.
Interaction of sodium benzoate with trypsin by spectroscopic techniques.

PubMed

Mu, Yue; Lin, Jing; Liu, Rutao

2011-12-01

The toxicity of sodium benzoate to trypsin was investigated by fluorescence spectroscopy, synchronous fluorescence spectroscopy, UV-visible absorption spectroscopy and circular dichroism (CD) spectroscopy under mimic physiological conditions. Sodium benzoate could unfold trypsin by decreasing the β-sheet structure, which leads to more exposure of internal amino acid groups and the obvious intrinsic fluorescence quenching with the rising concentration of sodium benzoate. The results of spectroscopic measurements indicated that sodium benzoate changed the internal microenvironment of trypsin and induced the alteration of the whole molecule, which were performed toxic effects on the organism. Trypsin and sodium benzoate interacted with each other to produce a substance by van der Waals forces and hydrogen bond, the model of which was shown by AutoDock software. Copyright © 2011 Elsevier B.V. All rights reserved.
Fluorescence Spectroscopy for the Monitoring of Food Processes.

PubMed

Ahmad, Muhammad Haseeb; Sahar, Amna; Hitzmann, Bernd

Different analytical techniques have been used to examine the complexity of food samples. Among them, fluorescence spectroscopy cannot be ignored in developing rapid and non-invasive analytical methodologies. It is one of the most sensitive spectroscopic approaches employed in identification, classification, authentication, quantification, and optimization of different parameters during food handling, processing, and storage and uses different chemometric tools. Chemometrics helps to retrieve useful information from spectral data utilized in the characterization of food samples. This contribution discusses in detail the potential of fluorescence spectroscopy of different foods, such as dairy, meat, fish, eggs, edible oil, cereals, fruit, vegetables, etc., for qualitative and quantitative analysis with different chemometric approaches.
Effect of perfluorooctane sulfonate on the conformation of wheat germ acid phosphatase.

PubMed

Xu, Dongmei; Jin, Jianchang; Shen, Tong; Wang, Yanhua

2013-11-01

Fluorescence spectroscopy was used to study the quenching mechanism, the type of force and the binding sites of perfluorooctane sulfonate (PFOS) on wheat germ acid phosphatase (ACPase). The results showed that the quenching effect of PFOS on ACPase was mainly due to a static quenching mechanism that occurred via the formation of hydrogen bonds and van der Waals forces. The results from synchronous fluorescence spectroscopy demonstrated that PFOS interacts with ACPase close to the tryptophan residues. In addition, synchronous fluorescence spectroscopy also showed that PFOS increases the hydrophobicity of the microenvironment of the tyrosine residues, hence decreasing the local polarity.
Preparation of liquid-core nanocapsules from poly[(ethylene oxide)-co-glycidol] with multiple hydrophobic linoleates at an oil-water interface and its encapsulation of pyrene.

PubMed

Ren, Yong; Wang, Guowei; Huang, Junlian

2007-06-01

A convenient approach is provided to prepare liquid-core nanocapsules by cross-linking an amphiphilic copolymer at an oil-water interface. The hydrophilic copolymer poly[(ethylene oxide)-co-glycidol] was prepared by anionic polymerization of ethylene oxide and ethoxyethyl glycidyl ether first, then the hydroxyl groups on the backbone were recovered after hydrolysis and partly modified by hydrophobic conjugated linoleic acid. The copolymer with multiple linoleate pendants was absorbed at an oil-water interface and then cross-linked to form stable nanocapsules. The mean diameter of the nanocapsule was below 350 nm, and the size distribution was relatively narrow (<0.2) at low concentrations of oil in acetone (<10 mg/mL). The particle size could be tuned easily by variation of the emulsification conditions. The nanocapsule was stable in water for at least 5 months, and the shell maintained its integrity after removal of the oily core by solvent. Pyrene was encapsulated in these nanocapsules, and a loading efficiency as high as 94% was measured by UV spectroscopy.
Responses of metabolic pathways to polycyclic aromatic compounds in flounder following oil spill in the Baltic Sea near the Estonian coast.

PubMed

Kreitsberg, Randel; Zemit, Irina; Freiberg, Rene; Tambets, Meelis; Tuvikene, Arvo

2010-09-15

In January 2006 an oil spill that involved approximately 40tons of heavy fuel oil affected more than 30km of the north-west coast of Estonia. The aquatic pollution of the coastal area of the Baltic Sea was monitored by measuring the content of selected polycyclic aromatic hydrocarbons (PAHs and PAH metabolites) in flounder (Platichthys flesus trachurus Duncker). One hundred and thirty-one fish were collected: muscle and liver tissues were analyzed by high-performance liquid chromatography (HPLC); bile and urine samples were analyzed using fixed wavelengths fluorescence. Fifteen different types of PAHs were analyzed in liver and muscle, and four types of PAH metabolites were analyzed in bile and urine (2-, 3-, 4- and 5-ringed PAH metabolites represented by naphthalene, phenanthrene, pyrene and benzo(a)pyrene). Fluorescence analyses were carried out using excitation/emission wavelength pairs: 290/380, 256/380, 341/383 and 380/430nm, respectively. There was a time-dependent decrease of PAH concentrations in liver (83%), bile (82%) and urine (113%). HPLC analysis of muscle tissues demonstrated low concentrations of single PAHs, but a decrease of concentrations during the study period was not observed. During the analyses concentrations of PAH metabolites in bile and urine were compared. Liver metabolic transformation activity is believed to exceed that of the kidney but the analyses demonstrated high metabolite concentration in fish urine, particularly of 4- and 5-ring PAH metabolites. The results indicate remarkable buffer capacity of hydrodynamically active sea as well as considerable importance of kidney-urine metabolic pathways in flounder physiology. 2010 Elsevier B.V. All rights reserved.
[Polycyclic aromatic hydrocarbons in ultrafine particles of diesel exhaust fumes--the use of ultrafast liquid chromatography].

PubMed

Małgorzata Szewczyńska; Małgorzata Pośniak

2014-01-01

The article presents the results of the determination of polycyclic aromatic hydrocarbons (PAHs) in the fine par ticles fraction emitted from 3 types of diesel fuels using ultra-high pressure liquid chromatography. Samples of diesel Eco, Verwa and Bio exhaust combustion fumes were generated at the model station which consisted of a diesel engine from the 2007 Diesel TDI 2.0. Personal Cascade Sioutas Impactor (IPCSI) with Teflon filters was used to collect samples of exhaust fume ultrafine particles. PAHs adsorbed on particulate fractions were analyzed by ultra-high pressure liquid chromatography with fluorescence detection (UHPLC/FL). Phenanthrene, fluoranthene, pyrene and chrysene present the highest concentration in the particulate matter emitted by an engine. The total contents of fine particles collected during engine operation on fuels Eco, Verwa and Bio were 134.2 μg/g, 183.8 μg/g and 153.4 μg/g, respectively, which makes 75%, 90% and 83% of the total PAHs, respectively. The highest content of benzo(a)pyrene determined in particles emitted during the combustion of fuels Eco and Bio was 1.5 μg/g and 1 μg/g, respectively. The study of the PAH concentration in the particles of fine fraction below 0.25 μm emitted from different fuels designed for diesel engines indicate that the exhaust gas content of carcinogens, including PAHs deposited on particulates, is still significant, regardless of the fuel. Application of ultrahigh pressure liquid chromatography with fluorescence detection for the analysis ofPAHs in the particles emitted in the fine fraction of diesel exhaust allowed to shorten the analysis time from 35 min to 8 min.
Preparation of Different Substitued Polypyridine Ligands, Ruthenium(II)-Bridged Complexes and Spectoscopıc Studies.

PubMed

Obali, Aslihan Yilmaz; Ucan, Halil Ismet

2016-09-01

Novel different substitued polypyridine ligands 4-((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenoxy)methyl)benzaldehyde (BA-PPY), (E)-N-(4-((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenoxy)methyl)benzylidene)-pyrene-4-amine (PR-PPY), (E)-N-(4-((4-(1H-imidazo[4,5-f][1,10] phenanthroline-2-yl)phenoxy)methyl)benzylidene)-1,10-phenanthroline-5amine (FN-PPY), 2-(4-(bromomethyl)phenyl)-1H-imidazo[4,5-f][1,10] phenanthroline (BR-PPY), 2-(4-(azidomethyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (N3-PPY) and triazole containing polypyridine ligand 3,4-bis[(4-(metoxy)-1,2,3-triazole)1-methylphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline)] benzaldehyde (BA-DIPPY) and Ruthenium(II) complexes were synthesized and characterized. Their photopysical properties were investigated. The complexes RuP(PR-PPY), RuB(PR-PPY, RuP(FN-PPY) and RuB(FN-PPY) exhibited a broad absorption bands at 485, 475, 476, and 453 nm, respectively, assignable to the spin-allowed MLCT (dπ-π*) transition. The emission maxima of the pyrene-appended polypyridine ligand PR-PPY was observed at λems = 616 nm and the phenanthroline-appended polypyridine ligand FN-PPY was observed at λems = 668 nm. And the emission maxima of the complexes RuP(PR-PPY), RuB(PR-PPY), RuP(FN-PPY) and RuB(FN-PPY) were observed at λems = 646, 646, 685 and 685 nm, respectively. As seen in fluorescence spectra, the fluorescence intensities of the ligands are higher than their metal complexes. This is because of quenching effect of Ruthenium(II) metal on chromophore groups.
Magnetic microsphere-confined graphene for the extraction of polycyclic aromatic hydrocarbons from environmental water samples coupled with high performance liquid chromatography-fluorescence analysis.

PubMed

Wang, Weina; Ma, Ruiyang; Wu, Qiuhua; Wang, Chun; Wang, Zhi

2013-06-07

In this paper, a magnetic microsphere-confined graphene adsorbent (Fe3O4@SiO2-G) was fabricated and used for the extraction of five polycyclic aromatic hydrocarbons (fluorene, anthracene, phenanthrene, fluoranthene and pyrene) from environmental water samples prior to high performance liquid chromatography with fluorescence detection. The Fe3O4@SiO2-G was characterized by various instrumental methods. Various experimental parameters that could affect the extraction efficiencies, such as the amount of Fe3O4@SiO2-G, the pH and ionic strength of sample solution, the extraction time and the desorption conditions, were investigated. Due to the high surface area and excellent adsorption capacity of the Fe3O4@SiO2-G, satisfactory extraction can be achieved with only 15mg of the adsorbent per 250mL solution and 5min extraction. Under the optimum conditions, a linear response was observed in the concentration range of 5-1500ngL(-1) for fluorene, 2.5-1500ngL(-1) for anthracene and 15-1500ngL(-1) for phenanthrene, fluoranthene and pyrene, with the correlation coefficients (r) ranging from 0.9897 to 0.9961. The limits of detection (S/N=3) of the method were between 0.5 and 5.0ngL(-1). The relative standard deviations (RSDs) were less than 5.6%. The recoveries of the method were in the range between 83.2% and 108.2%. The results indicated that this graphene-based magnetic nanocomposite had a great adsorptive ability toward the five polycyclic aromatic hydrocarbons from environmental water samples. Copyright © 2013 Elsevier B.V. All rights reserved.
Reflectance and fluorescence spectroscopies in photodynamic therapy

NASA Astrophysics Data System (ADS)

Finlay, Jarod C.

In vivo fluorescence spectroscopy during photodynamic therapy (PDT) has the potential to provide information on the distribution and degradation of sensitizers, the formation of fluorescent photoproducts and changes in tissue autofluorescence induced by photodynamic treatment. Reflectance spectroscopy allows quantification of light absorption and scattering in tissue. We present the results of several related studies of fluorescence and reflectance spectroscopy and their applications to photodynamic dosimetry. First, we develop and test an empirical method for the correction of the distortions imposed on fluorescence spectra by absorption and scattering in turbid media. We characterize the irradiance dependence of the in vivo photobleaching of three sensitizers, protoporphyrin IX (PpIX), Photofrin and mTHPC, in a rat skin model. The photobleaching and photoproduct formation of PpIX exhibit irradiance dependence consistent with singlet oxygen (1O2)-mediated bleaching. The bleaching of mTHPC occurs in two phases, only one of which is consistent with a 1O 2-mediated mechanism. Photofrin's bleaching is independent of irradiance, although its photoproduct formation is not. This can be explained by a mixed-mechanism bleaching model. Second, we develop an algorithm for the determination of tissue optical properties using diffuse reflectance spectra measured at a single source-detector separation and demonstrate the recovery of the hemoglobin oxygen dissociation curve from tissue-simulating phantoms containing human erythrocytes. This method is then used to investigate the heterogeneity of oxygenation response in murine tumors induced by carbogen inhalation. We find that while the response varies among animals and within each tumor, the majority of tumors exhibit an increase in blood oxygenation during carbogen breathing. We present a forward-adjoint model of fluorescence propagation that uses the optical property information acquired from reflectance spectroscopy to obtain the undistorted fluorescence spectrum over a wide range of optical properties. Finally, we investigate the ability of the forward-adjoint theory to extract undistorted fluorescence and optical property information simultaneously from a single measured fluorescence spectrum. This method can recover the hemoglobin oxygen dissociation curve in tissue-simulating phantoms with an accuracy comparable to that of reflectance-based methods while correcting distortions in the fluorescence over a wide range of absorption and scattering coefficients.
Direct probing of chromatography columns by laser-induced fluorescence

NASA Astrophysics Data System (ADS)

McGuffin, V. L.

1992-12-01

This report summarizes the progress and accomplishments of this research project from 1 Sep. 1989 to 28 Feb. 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe in supercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.
Determination of polycyclic aromatic hydrocarbons by four-way parallel factor analysis in presence of humic acid.

PubMed

Yang, Ruifang; Zhao, Nanjing; Xiao, Xue; Yu, Shaohui; Liu, Jianguo; Liu, Wenqing

2016-01-05

There is not effective method to solve the quenching effect of quencher in fluorescence spectra measurement and recognition of polycyclic aromatic hydrocarbons in aquatic environment. In this work, a four-way dataset combined with four-way parallel factor analysis is used to identify and quantify polycyclic aromatic hydrocarbons in the presence of humic acid, a fluorescent quencher and an ubiquitous substance in aquatic system, through modeling the quenching effect of humic acid by decomposing the four-way dataset into four loading matrices corresponding to relative concentration, excitation spectra, emission spectra and fluorescence quantum yield, respectively. It is found that Phenanthrene, pyrene, anthracene and fluorene can be recognized simultaneously with the similarities all above 0.980 between resolved spectra and reference spectra. Moreover, the concentrations of them ranging from 0 to 8μgL(-1) in the test samples prepared with river water could also be predicted successfully with recovery rate of each polycyclic aromatic hydrocarbon between 100% and 120%, which were higher than those of three-way PARAFAC. These results demonstrate that the combination of four-way dataset with four-way parallel factor analysis could be a promising method to recognize the fluorescence spectra of polycyclic aromatic hydrocarbons in the presence of fluorescent quencher from both qualitative and quantitative perspective. Copyright © 2015 Elsevier B.V. All rights reserved.
Evaluation of soil pH and moisture content on in-situ ozonation of pyrene in soils.

PubMed

Luster-Teasley, S; Ubaka-Blackmoore, N; Masten, S J

2009-08-15

In this study, pyrene spiked soil (300 ppm) was ozonated at pH levels of 2, 6, and 8 and three moisture contents. It was found that soil pH and moisture content impacted the effectiveness of PAH oxidation in unsaturated soils. In air-dried soils, as pH increased, removal increased, such that pyrene removal efficiencies at pH 6 and pH 8 reached 95-97% at a dose of 2.22 mg O(3)/mg pyrene. Ozonation at 16.2+/-0.45 mg O(3)/ppm pyrene in soil resulted in 81-98% removal of pyrene at all pH levels tested. Saturated soils were tested at dry, 5% or 10% moisture conditions. The removal of pyrene was slower in moisturized soils, with the efficiency decreasing as the moisture content increased. Increasing the pH of the soil having a moisture content of 5% resulted in improved pyrene removals. On the contrary, in the soil having a moisture content of 10%, as the pH increased, pyrene removal decreased. Contaminated PAH soils were stored for 6 months to compare the efficiency of PAH removal in freshly contaminated soil and aged soils. PAH adsorption to soil was found to increase with longer exposure times; thus requiring much higher doses of ozone to effectively oxidize pyrene.
L-cysteine-capped core/shell/shell quantum dot-graphene oxide nanocomposite fluorescence probe for polycyclic aromatic hydrocarbon detection.

PubMed

Adegoke, Oluwasesan; Forbes, Patricia B C

2016-01-01

Environmental pollutants, such as the polycyclic aromatic hydrocarbons (PAHs), become widely distributed in the environment after emission from a range of sources, and they have potential biological effects, including toxicity and carcinogenity. In this work, we have demonstrated the analytical potential of a covalently linked L-cysteine-capped CdSeTe/ZnSe/ZnS core/shell/shell quantum dot (QD)-graphene oxide (GO) nanocomposite fluorescence probe to detect PAH compounds in aqueous solution. Water-soluble L-cysteine-capped CdSeTe/ZnSe/ZnS QDs were synthesized for the first time and were covalently bonded to GO. The fluorescence of the QD-GO nanocomposite was enhanced relative to the unconjugated QDs. Various techniques including TEM, SEM, HRSEM, XRD, Raman, FT-IR, UV/vis and fluorescence spectrophotometry were employed to characterize both the QDs and the QD-GO nanocomposite. Four commonly found priority PAH analytes namely; phenanthrene (Phe), anthracene (Ant), pyrene (Py) and naphthalene (Naph), were tested and it was found that each of the PAH analytes enhanced the fluorescence of the QD-GO probe. Phe was selected for further studies as the PL enhancement was significantly greater for this PAH. A limit of detection (LOD) of 0.19 µg/L was obtained for Phe under optimum conditions, whilst the LOD of Ant, Py and Naph were estimated to be ~0.26 µg/L. The fluorescence detection mechanism is proposed. Copyright © 2015 Elsevier B.V. All rights reserved.
Fluorescence correlation spectroscopy of diffusion probed with a Gaussian Lorentzian spatial distribution

NASA Astrophysics Data System (ADS)

Marrocco, Michele

2007-11-01

Fluorescence correlation spectroscopy is fundamental in many physical, chemical and biological studies of molecular diffusion. However, the concept of fluorescence correlation is founded on the assumption that the analytical description of the correlation decay of diffusion can be achieved if the spatial profile of the detected volume obeys a three-dimensional Gaussian distribution. In the present Letter, the analytical result is instead proven for the fundamental Gaussian-Lorentzian profile.

Fluorescence lifetime spectroscopy in multiple-scattering environments: an application to biotechnology

NASA Astrophysics Data System (ADS)

Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio

1999-07-01

Over the past few years, there has been significant research activity devoted to the application of fluorescence spectroscopy to strongly scattering media, where photons propagate diffusely. Much of this activity focused on fluorescence as a source of contrast enhancement in optical tomography. Our efforts have emphasized the quantitative recovery of fluorescence parameters for spectroscopy. Using a frequency-domain diffusion-based model, we have successfully recovered the lifetime, the absolute quantum yield, the fluorophore concentration, and the emission spectrum of the fluorophore, as well as the absorption and the reduced scattering coefficients at the emission wavelength of the medium in different measurements. In this contribution, we present a sensitive monitor of the binding between ethidium bromide and bovine cells in fresh milk. The spectroscopic contrast was the approximately tenfold increase in the ethidium bromide lifetime upon binding to DNA. The measurement clearly demonstrated that we could quantitatively measure the density of cells in the milk, which is an application vital to the tremendous economic burden of bovine subclinical mastitis detection. Furthermore, we may in principle use the spirit of this technique as a quantitative monitor of the binding of fluorescent drugs inside tissues. This is a first step towards lifetime spectroscopy in tissues.
Influence of algal and bacterial particulate organic matter on benzo[a]pyrene bioaccumulation in Daphnia magna.

PubMed

Gourlay, Catherine; Mouchel, Jean-Marie; Tusseau-Vuillemin, Marie-Hélène; Garric, Jeanne

2005-06-15

In order to better asses the influence of organic matter on the bioavailability of hydrophobic organic contaminants, the effect of algae and POM of bacterial origin on the bioaccumulation of benzo[a]pyrene in Daphnia magna was evaluated. The bioaccumulation was monitored with increasing concentrations of particulate organic matter (POM) and dissolved organic matter (DOM). In all experiments, the presence of POM greatly reduced the bioaccumulation of benzo[a]pyrene. The reduction was more pronounced in the presence of algae, for which we observed a 99%-reduction effect in the presence of 6 x10 (5) cell/mL (equivalent to 5.3 mg C/L). The bioaccumulation of benzo[a]pyrene was decreased by 49% by organic matter of bacterial origin at 4.7 mg C/L. Assuming that benzo[a]pyrene was partitioned between water, DOM and POM and supposing that D. magna accumulated free benzo[a]pyrene via respiration and POM-bond benzo[a]pyrene via ingestion, bioaccumulation data allowed to estimate the dietary uptake rate of benzo[a]pyrene as well as partitioning coefficients K(POC) and K(DOC). Despite the ingestion of contaminated particles, we could not observe any dietary uptake of benzo[a]pyrene in daphnids. We verified, as usually supposed, that the bioaccumulation of benzo[a]pyrene to D. magna occurs mainly via direct contact. Very high partitioning coefficients (log K(POC) between 5.2 and 6.2) were estimated. This study pointed out the great influence of biogenic organic matter on the fate and the bioavailability of benzo[a]pyrene in aquatic ecosystems.
A total internal reflection-fluorescence correlation spectroscopy setup with pulsed diode laser excitation

NASA Astrophysics Data System (ADS)

Weger, Lukas; Hoffmann-Jacobsen, Kerstin

2017-09-01

Fluorescence correlation spectroscopy (FCS) measures fluctuations in a (sub-)femtoliter volume to analyze the diffusive behavior of fluorescent particles. This highly sensitive method has proven to be useful for the analysis of dynamic biological systems as well as in chemistry, physics, and material sciences. It is routinely performed with commercial fluorescence microscopes, which provide a confined observation volume by the confocal technique. The evanescent wave of total internal reflectance (TIR) is used in home-built systems to permit a surface sensitive FCS analysis. We present a combined confocal and TIR-FCS setup which uses economic low-power pulsed diode lasers for excitation. Excitation and detection are coupled to time-correlated photon counting hardware. This allows simultaneous fluorescence lifetime and FCS measurements in a surface-sensitive mode. Moreover, the setup supports fluorescence lifetime correlation spectroscopy at surfaces. The excitation can be easily switched between TIR and epi-illumination to compare the surface properties with those in liquid bulk. The capabilities of the presented setup are demonstrated by measuring the diffusion coefficients of a free dye molecule, a labeled polyethylene glycol, and a fluorescent nanoparticle in confocal as well as in TIR-FCS.
One-Step Synthesis of Fluorescent Boron Nitride Quantum Dots via a Hydrothermal Strategy Using Melamine as Nitrogen Source for the Detection of Ferric Ions.

PubMed

Huo, Bingbing; Liu, Bingping; Chen, Tao; Cui, Liang; Xu, Gengfang; Liu, Mengli; Liu, Jingquan

2017-10-10

A facile and effective approach for the preparation of functionalized born nitride quantum dots (BNQDs) with blue fluorescence was explored by the hydrothermal treatment of the mixture of boric acid and melamine at 200 °C for 15 h. The as-prepared BNQDs were characterized by transmission electron microscopy (TEM), high-resolution TEM, atomic force microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The single layered BNQDs with the average size of 3 nm showed a blue light emission under the illumination of the UV light. The BNQDs could be easily dispersed in an aqueous medium and applied as fluorescent probes for selective detection of Fe 3+ with remarkable selectivity and sensitivity (the lowest detection limit was 0.3 μM). The fluorescence fiber imaging demonstrated that the as-prepared quantum dots could be used as a valuable fluorchrome. Therefore, the BNQDs could be envisioned for potential applications in many fields such as biocompatible staining, fluorescent probes, and biological labeling.
Spectroscopic studies on the interaction of a water-soluble cationic porphyrin with proteins

NASA Astrophysics Data System (ADS)

Ma, Hong-Min; Chen, Xin; Zhang, Nuo; Han, Yan-Yan; Wu, Dan; Du, Bin; Wei, Qin

2009-04-01

The interaction of a water-soluble cationic porphyrin, meso-tetrakis (4- N, N, N-trimethylanilinium) porphyrin (TMAP), with two proteins, bovine serum albumin (BSA) and human serum albumin (HSA), was studied by UV-vis absorption spectroscopy, fluorescence spectroscopy, fluorescence anisotropy and synchronous fluorescence spectroscopy at neutral aqueous solutions. Free base TMAP bound to proteins as monomers and no aggregation was observed. The binding of TMAP quenched the fluorescence of the protein. On the contrary, the fluorescence of TMAP was enhanced and the fluorescence anisotropy increased due to the binding. The direct static binding mechanism could account for the quenching by TMAP and the binding constants were calculated. TMAP showed a higher quenching efficiency and binding constant of HSA than BSA. The binding of TMAP had no obvious effect on the molecular conformation of the protein. There was only one binding site for TMAP and it was located on the surface of the protein molecule. Electrostatic force played an important role in the binding due to the opposite charges on porphyrin and the proteins.
Spectroscopic studies on the interaction of a water-soluble cationic porphyrin with proteins.

PubMed

Ma, Hong-Min; Chen, Xin; Zhang, Nuo; Han, Yan-Yan; Wu, Dan; Du, Bin; Wei, Qin

2009-04-01

The interaction of a water-soluble cationic porphyrin, meso-tetrakis (4-N,N,N-trimethylanilinium) porphyrin (TMAP), with two proteins, bovine serum albumin (BSA) and human serum albumin (HSA), was studied by UV-vis absorption spectroscopy, fluorescence spectroscopy, fluorescence anisotropy and synchronous fluorescence spectroscopy at neutral aqueous solutions. Free base TMAP bound to proteins as monomers and no aggregation was observed. The binding of TMAP quenched the fluorescence of the protein. On the contrary, the fluorescence of TMAP was enhanced and the fluorescence anisotropy increased due to the binding. The direct static binding mechanism could account for the quenching by TMAP and the binding constants were calculated. TMAP showed a higher quenching efficiency and binding constant of HSA than BSA. The binding of TMAP had no obvious effect on the molecular conformation of the protein. There was only one binding site for TMAP and it was located on the surface of the protein molecule. Electrostatic force played an important role in the binding due to the opposite charges on porphyrin and the proteins.
Comparison of fluorescence rejection methods of baseline correction and shifted excitation Raman difference spectroscopy

NASA Astrophysics Data System (ADS)

Cai, Zhijian; Zou, Wenlong; Wu, Jianhong

2017-10-01

Raman spectroscopy has been extensively used in biochemical tests, explosive detection, food additive and environmental pollutants. However, fluorescence disturbance brings a big trouble to the applications of portable Raman spectrometer. Currently, baseline correction and shifted-excitation Raman difference spectroscopy (SERDS) methods are the most prevailing fluorescence suppressing methods. In this paper, we compared the performances of baseline correction and SERDS methods, experimentally and simulatively. Through the comparison, it demonstrates that the baseline correction can get acceptable fluorescence-removed Raman spectrum if the original Raman signal has good signal-to-noise ratio, but it cannot recover the small Raman signals out of large noise background. By using SERDS method, the Raman signals, even very weak compared to fluorescence intensity and noise level, can be clearly extracted, and the fluorescence background can be completely rejected. The Raman spectrum recovered by SERDS has good signal to noise ratio. It's proved that baseline correction is more suitable for large bench-top Raman system with better quality or signal-to-noise ratio, while the SERDS method is more suitable for noisy devices, especially the portable Raman spectrometers.
Analysis of surgical margins in oral cancer using in situ fluorescence spectroscopy.

PubMed

Francisco, Ana Lucia Noronha; Correr, Wagner Rafael; Pinto, Clóvis Antônio Lopes; Gonçalves Filho, João; Chulam, Thiago Celestino; Kurachi, Cristina; Kowalski, Luiz Paulo

2014-06-01

Oral cancer is a public health problem with high prevalence in the population. Local tumor control is best achieved by complete surgical resection with adequate margins. A disease-free surgical margin correlates with a lower rate of local recurrence and a higher rate of disease-free survival. Fluorescence spectroscopy is a noninvasive diagnostic tool that can aid in real-time cancer detection. The technique, which evaluates the biochemical composition and structure of tissue fluorescence, is relatively simple, fast and, accurate. This study aimed to compare oral squamous cell carcinoma lesions to surgical margins and the mucosa of healthy volunteers by fluorescence spectroscopy. The sample consisted of 56 individuals, 28 with oral squamous cell carcinoma and 28 healthy volunteers with normal oral mucosa. Thirty six cases (64.3%) were male and the mean age was 60.9 years old. The spectra were classified and compared to histopathology to determine fluorescence efficiency for diagnostic discrimination of tumors. In the analysis of the other cases we observed discrimination between normal mucosa, injury and margins. At two-year follow up, three individuals had local recurrence, and in two cases investigation fluorescence in the corresponding area showed qualitative differences in spectra between the recurrence area and the area without recurrence at the same anatomical site in the same patient. In situ analysis of oral mucosa showed the potential of fluorescence spectroscopy as a diagnostic tool that can aid in discrimination of altered mucosa and normal mucosa. Copyright © 2014 Elsevier Ltd. All rights reserved.
A Comparative Study of the Metabolism of 6-Methylbenzo [A] Pyrene and Benzo [A] Pyrene by Rat Liver Microsomes

DTIC Science & Technology

1984-02-24

147. Dewhurst, F., and Kitchen, D. A. (1972). Synthesis and properties of 6-substituted benzo [a] pyrene derivatives. J_. £. 1 . Perkins I, 710-712...group results in the formation of 6-hydroxymathylbenzo[a]pyrene (6-OHMBaP) which can be further metabolized to both the 1 - and 3-phenols of 6...LIST OF TABLES LIST OF FIGURES xi BACKGROUND 1 Introduction 1 Metabolism of PAH 1 Microsomal Metabolism of Benzo[a]pyrene 2 Inducers of
Development of a homogeneous assay format for p53 antibodies using fluorescence correlation spectroscopy

NASA Astrophysics Data System (ADS)

Neuweiler, Hannes; Scheffler, Silvia; Sauer, Markus

2005-08-01

The development of reliable methods for the detection of minute amounts of antibodies directly in homogeneous solution represents one of the major tasks in the current research field of molecular diagnostics. We demonstrate the potential of fluorescence correlation spectroscopy (FCS) in combination with quenched peptide-based fluorescence probes for sensitive detection of p53 antibodies directly in homogeneous solution. Single tryptophan (Trp) residues in the sequences of short, synthetic peptide epitopes of the human p53 protein efficiently quench the fluorescence of an oxazine fluorophore attached to the amino terminal ends of the peptides. The fluorescence quenching mechanism is thought to be a photoinduced electron transfer reaction from Trp to the dye enabled by the formation of intramolecular complexes between dye and Trp. Specific recognition of the epitope by the antibody confines the conformational flexibility of the peptide. Consequently, complex formation between dye and Trp is abolished and fluorescence is recovered. Using fluorescence correlation spectroscopy (FCS), antibody binding can be monitored observing two parameters simultaneously: the diffusional mobility of the peptide as well as the quenching amplitude induced by the conformational flexibility of the peptide change significantly upon antibody binding. Our data demonstrate that FCS in combination with fluorescence-quenched peptide epitopes opens new possibilities for the reliable detection of antibody binding events in homogeneous solution.
Photodynamic tumor therapy and on-line fluorescence spectroscopy after aminolevulinic acid administration using 633-nm light as therapeutic and fluorescence excitation radiation

NASA Astrophysics Data System (ADS)

Koenig, Karsten; Kienle, Alwin; Boehncke, Wolf-Henning; Kaufmann, Roland; Rueck, Angelika C.; Meier, Thomas H.; Steiner, Rudolf W.

1994-03-01

PDT and on-line fluorescence spectroscopy were carried out on human tumors after ALA- administration using 633 nm-light of a dye laser as therapeutic radiation and as fluorescence excitation radiation. This has the following advantages: (1) use of one laser for PDT and fluorescence diagnosis only, (2) the possibility of on-line fluorescence measurements, and (3) excitation of protoporphyrin molecules in deep tissue layers. Monte Carlo calculations were carried out to determine the excitation and fluorescence photon distribution in the case of red and violet excitation radiation. The results show the possibility of depth-resolved measurements on the fluorophore distribution by variation of the excitation wavelength. The influence of remitted excitation light and of the spontaneous radiation from the laser as well as the possible excitation of food-based degradation products of chlorophyll has to be considered in high-sensitive fluorescence measurements.
Depth-resolved fluorescence of human ectocervical tissue

NASA Astrophysics Data System (ADS)

Wu, Yicong; Xi, Peng; Cheung, Tak-Hong; Yim, So Fan; Yu, Mei-Yung; Qu, Jianan Y.

2005-04-01

The depth-resolved autofluorescence of normal and dysplastic human ectocervical tissue within 120um depth were investigated utilizing a portable confocal fluorescence spectroscopy with the excitations at 355nm and 457nm. From the topmost keratinizing layer of all ectocervical tissue samples, strong keratin fluorescence with the spectral characteristics similar to collagen was observed, which created serious interference in seeking the correlation between tissue fluorescence and tissue pathology. While from the underlying non-keratinizing epithelial layer, the measured NADH fluorescence induced by 355nm excitation and FAD fluorescence induced by 457nm excitation were strongly correlated to the tissue pathology. The ratios between NADH over FAD fluorescence increased statistically in the CIN epithelial relative to the normal and HPV epithelia, which indicated increased metabolic activity in precancerous tissue. This study demonstrates that the depth-resolved fluorescence spectroscopy can reveal fine structural information on epithelial tissue and potentially provide more accurate diagnostic information for determining tissue pathology.
Solvatochromic probe behavior within choline chloride-based deep eutectic solvents: effect of temperature and water.

PubMed

Pandey, Ashish; Pandey, Siddharth

2014-12-18

Deep eutectic solvents (DESs) have shown potential as promising environmentally friendly alternatives to conventional solvents. Many common and popular DESs are obtained by simply mixing a salt and a H-bond donor. Properties of such a DES depend on its constituents. Change in temperature and addition of water, a benign cosolvent, can change the physicochemical properties of DESs. The effect of changing temperature and addition of water on solvatochromic probe behavior within three DESs formed from choline chloride combined with 1,2-ethanediol, glycerol, and urea, respectively, in 1:2 mol ratios termed ethaline, glyceline, and reline is presented. Increase in temperature results in reduced H-bond donating acidity of the DESs. Dipolarity/polarizability and H-bond accepting basicity do not change with changing temperature of the DESs. The response of the fluorescence probe pyrene also indicates a decrease in the polarity of the DESs as temperature is increased. Addition of water to DES results in increased dipolarity/polarizability and a decrease in H-bond accepting basicity. Except for pyrene, solvatochromic probes exhibit responses close to those predicted from ideal-additive behavior with slight preferential solvation by DES within the aqueous mixtures. Pyrene response reveals significant preferential solvation by DES and/or the presence of solvent-solvent interactions, especially within aqueous mixtures of ethaline and glyceline, the DESs constituted of H-bond donors with hydroxyl functionalities. FTIR absorbance and Raman spectroscopic measurements of aqueous DES mixtures support the outcomes from solvatochromic probe responses. Aqueous mixtures of ethaline and glyceline possess relatively more interspecies H-bonds as compared to aqueous mixtures of reline, where interstitial accommodation of water within the reline molecular network appears to dominate.
High human exposure to pyrene (polycyclic aromatic hydrocarbon) in Kinshasa, a capital of the Democratic Republic of Congo.

PubMed

Tuakuila, Joel; Kabamba, Martin; Mata, Honoré

2013-01-01

Data on human exposure to chemicals in Africa are scarce. A biomonitoring study was conducted in a representative sample of the population in Kinshasa (Democratic Republic of Congo) to document exposure to polycyclic aromatics hydrocarbons. 1-hydroxypyrene (1-OHP) was measured by HPLC fluorescence in spot urine samples from 220 individuals (50.5% women), aged 6-70 years living in the urban area and from 50 additional subjects from the sub-rural area of Kinshasa. Data were compiled as geometric means and selected percentiles, expressed without (μg/L) or with creatinine adjustment (μg/g cr). Multiple regression analyses were applied to factors (creatinine, grilled meat habits and smoking habits) influencing 1-OHP (stepwise procedure, criteria: probability F to enter ≤ 0.05 and probability F to remove ≥ 0.10). According to the regression models, creatinine, grilled meat habits and smoking habits contribute to explain 45% of the variation in population's urinary 1-OHP by the environmental exposure. Overall, living in urban area of Kinshasa was associated with increased levels of 1-OHP in urine as compared to a population living in the sub-rural area [GM: 1.8 μg/L (n = 220) versus 1.4 μg/L (n = 50), p < 0.01] as well as compared to the reference values from databases involving American or German populations. This study reveals the high pyrene (PAH) exposure of the Kinshasa population. However, more work, with a rigorous design in the exposed population (monitoring of air concentrations and identifying other sources of pyrene -PAH exposure), is needed to establish further documentation.
High human exposure to pyrene (polycyclic aromatic hydrocarbon) in Kinshasa, a capital of the Democratic Republic of Congo

PubMed Central

2013-01-01

Background Data on human exposure to chemicals in Africa are scarce. A biomonitoring study was conducted in a representative sample of the population in Kinshasa (Democratic Republic of Congo) to document exposure to polycyclic aromatics hydrocarbons. Methods 1-hydroxypyrene (1-OHP) was measured by HPLC fluorescence in spot urine samples from 220 individuals (50.5% women), aged 6–70 years living in the urban area and from 50 additional subjects from the sub-rural area of Kinshasa. Data were compiled as geometric means and selected percentiles, expressed without (μg/L) or with creatinine adjustment (μg/g cr). Multiple regression analyses were applied to factors (creatinine, grilled meat habits and smoking habits) influencing 1-OHP (stepwise procedure, criteria: probability F to enter ≤ 0.05 and probability F to remove ≥ 0.10). Results According to the regression models, creatinine, grilled meat habits and smoking habits contribute to explain 45% of the variation in population’s urinary 1-OHP by the environmental exposure. Overall, living in urban area of Kinshasa was associated with increased levels of 1-OHP in urine as compared to a population living in the sub-rural area [GM: 1.8 μg/L (n = 220) versus 1.4 μg/L (n = 50), p < 0.01] as well as compared to the reference values from databases involving American or German populations. Conclusion This study reveals the high pyrene (PAH) exposure of the Kinshasa population. However, more work, with a rigorous design in the exposed population (monitoring of air concentrations and identifying other sources of pyrene –PAH exposure), is needed to establish further documentation. PMID:23782930
The modifier effects of chymotrypsin and trypsin enzymes on fluorescence lifetime distribution of "N-(1-pyrenyl)maleimide-bovine serum albumin" complex.

PubMed

Özyiğit, İbrahim Ethem; Karakuş, Emine; Pekcan, Önder

2016-02-05

Chymotrypsin and trypsin are the well known proteolytic enzymes, both of which are synthesized in the pancreas as their precursors - the inactive forms; chymotrypsinogen and trypsinogen - and then are released into the duodenum to cut proteins into smaller peptides. In this paper, the effects of activities of chymotrypsin and trypsin enzymes on fluorescence lifetime distributions of the substrat bovine serum albumin (BSA) modified with N-(1-pyrenyl)maleimide (PM) were examined. In the labeling study of BSA with PM, it is aimed to attach PM to the single free thiol (Cys34) and to all the free amine groups in accessible positions in order to produce excimers of pyrene planes of the possible highest amount to form the lifetime distributions in the widest range, that may show specifically distinguishing changes resulting from the activities of the proteases. The time resolved spectrofluorometer was used to monitor fluorescence decays, which were analyzed by using the exponential series method (ESM) to obtain the changes of lifetime distributions. After the exposure of the synthesized substrat PM-BSA to the enzymes, the fluorescence lifetime distributions exhibited different structures which were attributed to the different activities of the proteases. Copyright © 2015 Elsevier B.V. All rights reserved.
Toward Fourier interferometry fluorescence excitation/emission imaging of malignant cells combined with photoacoustic microscopy

NASA Astrophysics Data System (ADS)

Kohen, Elli; Hirschberg, Joseph G.; Berry, John P.; Ozkutuk, Nuri; Ornek, Ceren; Monti, Marco; Leblanc, Roger M.; Schachtschabel, Dietrich O.; Haroon, Sumaira

2003-10-01

Dual excitation fluorescence imaging has been used as a first step towards multi-wavelength excitation/emission fluorescence spectral imaging. Target cells are transformed keratinocytes, and other osteosarcoma, human breast and color cancer cells. Mitochondrial membrane potential probes, e.g. TMRM (tetramethylrhodamine methyl ester), Mitotracker Green (Molecular Probes, Inc., Eugene OR,USA; a recently synthesized mitochondrial oxygen probe, [PRE,P1"- pyrene butyl)-2-rhodamine ester] allow dual excitation in the UV plus in teh blue-green spectral regions. Also, using the natural endogenous probe NAD(P)H, preliminary results indicate mitochondrial responses to metabolic challenges (e.g. glucose addition), plus changes in mitochonrial distribution and morphology. In terms of application to biomedicine (for diagnostiscs, prognostsics and drug trials) three parameters have been selected in addition to the natural probe NAD(P)H, i.e. vital fluorescence probing of mitochondria, lysosomes and Golgi apparatus. It is hoped that such a multiparameter approach will allow malignant cell characterization and grading. A new area being introduced is the use of similar methodology for biotechnical applications such as the study of the hydrogen-producing alga Chlamydomonas Reinhardtii, and possible agricultural applications, such as Saccharomyces yeast for oenology. Complementation by Photoacoustic Microscopy is also contemplated, to study the internal conversion component which follows the excitation by photons.
Implementation of anion-receptor macrocycles in supramolecular tandem assays for enzymes involving nucleotides as substrates, products, and cofactors.

PubMed

Florea, Mara; Nau, Werner M

2010-03-07

A supramolecular tandem assay for direct continuous monitoring of nucleotide triphosphate-dependent enzymes such as potato apyrase is described. The underlying principle of the assay relies on the use of anion-receptor macrocycles in combination with fluorescent dyes as reporter pairs. A combinatorial approach was used to identify two complementary reporter pairs, i.e. an amino-gamma-cyclodextrin with 2-anilinonaphtalene-6-sulfonate (ANS) as dye (fluorescence enhancement factor of 17 upon complexation) and a polycationic cyclophane with 8-hydroxy-1,3,6-pyrene trisulfonate (HPTS) as dye (fluorescence decrease by a factor of more than 2000), which allow the kinetic monitoring of potato apyrase activity at different ATP concentration ranges (microM and mM) with different types of photophysical responses (switch-ON and switch-OFF). Competitive fluorescence titrations revealed a differential binding of ATP (strongest competitor) versus ADP and AMP, which constitutes the prerequisite for monitoring enzymatic conversions (dephosphorylation or phosphorylation) involving nucleotides. The assay was tested for different enzyme and substrate concentrations and exploited for the screening of activating additives, namely divalent transition metal ions (Ni(2+), Mg(2+), Mn(2+), and Ca(2+)). The transferability of the assay could be demonstrated by monitoring the dephosphorylation of other nucleotide triphosphates (GTP, TTP, and CTP).
Time-resolved resonance fluorescence spectroscopy for study of chemical reactions in laser-induced plasmas.

PubMed

Liu, Lei; Deng, Leimin; Fan, Lisha; Huang, Xi; Lu, Yao; Shen, Xiaokang; Jiang, Lan; Silvain, Jean-François; Lu, Yongfeng

2017-10-30

Identification of chemical intermediates and study of chemical reaction pathways and mechanisms in laser-induced plasmas are important for laser-ablated applications. Laser-induced breakdown spectroscopy (LIBS), as a promising spectroscopic technique, is efficient for elemental analyses but can only provide limited information about chemical products in laser-induced plasmas. In this work, time-resolved resonance fluorescence spectroscopy was studied as a promising tool for the study of chemical reactions in laser-induced plasmas. Resonance fluorescence excitation of diatomic aluminum monoxide (AlO) and triatomic dialuminum monoxide (Al 2 O) was used to identify these chemical intermediates. Time-resolved fluorescence spectra of AlO and Al 2 O were used to observe the temporal evolution in laser-induced Al plasmas and to study their formation in the Al-O 2 chemistry in air.
LASER BIOLOGY AND MEDICINE: A laser-spectroscopy system for fluorescent diagnostics and photodynamic therapy of diseases of eye retina and choroid

NASA Astrophysics Data System (ADS)

Meerovich, G. A.; Shevchik, S. A.; Loshchenov, M. V.; Budzinskaya, M. V.; Ermakova, N. A.; Kharnas, S. S.

2002-11-01

A laser-spectroscopy system for the fluorescent diagnostics and photodynamic therapy of pathologic eye-fundus changes combined with the use of the Photosens compound is developed. The system is tested on experimental animals (mice and rabbits).

Biological Interaction of Molybdenocene Dichloride with Bovine Serum Albumin Using Fluorescence Spectroscopy

ERIC Educational Resources Information Center

Domínguez, Moralba; Cortes-Figueroa, Jose´ E.; Meléndez, Enrique

2018-01-01

Bioinorganic topics are ubiquitous in the inorganic chemistry curriculum; however, experiments to enhance understanding of related topics are scarce. In this proposed laboratory, upper undergraduate students assess the biological interaction of molybdenocene dichloride (Cp2MoCl2) with bovine serum albumin (BSA) by fluorescence spectroscopy.…
DETECTION OF MERCURIC BROMIDE IN A GAS PHASE FLOW CELL BY LASER PHOTOFRAGMENT FLUORESCENCE SPECTROSCOPY. (R825380)

EPA Science Inventory

Photofragment fluorescence (PFF) spectroscopy offers real-time monitoring
capability with high-analytical sensitivity and selectivity for volatile mercury
compounds found in process gas streams, such as incinerator stacks. In this
work, low concentrations (6 ppb to...
Molecules for Fluorescence Detection of Specific Chemicals

NASA Technical Reports Server (NTRS)

Fedor, Steve

2008-01-01

A family of fluorescent dye molecules has been developed for use in on-off fluorescence detection of specific chemicals. By themselves, these molecules do not fluoresce. However, when exposed to certain chemical analytes in liquid or vapor forms, they do fluoresce (see figure). These compounds are amenable to fixation on or in a variety of substrates for use in fluorescence-based detection devices: they can be chemically modified to anchor them to porous or non-porous solid supports or can be incorporated into polymer films. Potential applications for these compounds include detection of chemical warfare agents, sensing of acidity or alkalinity, and fluorescent tagging of proteins in pharmaceutical research and development. These molecules could also be exploited for use as two-photon materials for photodynamic therapy in the treatment of certain cancers and other diseases. A molecule in this family consists of a fluorescent core (such as an anthracene or pyrene) attached to two end groups that, when the dye is excited by absorption of light, transfer an electron to the core, thereby quenching the fluorescence. The end groups can be engineered so that they react chemically with certain analytes. Upon reaction, electrons on the end groups are no longer available for transfer to the core and, consequently, the fluorescence from the core is no longer quenched. The chemoselectivity of these molecules can be changed by changing the end groups. For example, aniline end groups afford a capability for sensing acids or acid halides (including those contained in chemical warfare agents). Pyridine or bipyridyl end groups would enable sensing of metal ions. Other chemicals that can be selectively detected through suitable choice of end groups include glucose and proteins. Moreover, the fluorescent cores can be changed to alter light-absorption and -emission characteristics: anthracene cores fluoresce at wavelengths around 500 nm, whereas perylene cores absorb and emit at wavelengths of about 600 nm.
Confocal fluorescence techniques in industrial application

NASA Astrophysics Data System (ADS)

Eggeling, Christian; Gall, Karsten; Palo, Kaupo; Kask, Peet; Brand, Leif

2003-06-01

The FCS+plus family of evaluation tools for confocal fluorescence spectroscopy, which was developed during recent years, offers a comprehensive view to a series of fluorescence properties. Originating in fluorescence correlation spectroscopy (FCS) and using similar experimental equipment, a system of signal processing methods such as fluorescence intensity distribution analysis (FIDA) was created to analyze in detail the fluctuation behavior of fluorescent particles within a small area of detection. Giving simultaneous access to molecular parameters like concentration, translational and rotational diffusion, molecular brightness, and multicolor coincidence, this portfolio was enhanced by more traditional techniques of fluorescence lifetime as well as time-resolved anisotropy determination. The cornerstones of the FCS+plus methodology will be shortly described. The inhibition of a phosphatase enzyme activity gives a comprehensive industrial application that demonstrates FCS+plus' versatility and its potential for pharmaceutical drug discovery.
Fluorescence spectroscopy using indocyanine green for lymph node mapping

NASA Astrophysics Data System (ADS)

Haj-Hosseini, Neda; Behm, Pascal; Shabo, Ivan; Wârdell, Karin

2014-02-01

The principles of cancer treatment has for years been radical resection of the primary tumor. In the oncologic surgeries where the affected cancer site is close to the lymphatic system, it is as important to detect the draining lymph nodes for metastasis (lymph node mapping). As a replacement for conventional radioactive labeling, indocyanine green (ICG) has shown successful results in lymph node mapping; however, most of the ICG fluorescence detection techniques developed are based on camera imaging. In this work, fluorescence spectroscopy using a fiber-optical probe was evaluated on a tissue-like ICG phantom with ICG concentrations of 6-64 μM and on breast tissue from five patients. Fiber-optical based spectroscopy was able to detect ICG fluorescence at low intensities; therefore, it is expected to increase the detection threshold of the conventional imaging systems when used intraoperatively. The probe allows spectral characterization of the fluorescence and navigation in the tissue as opposed to camera imaging which is limited to the view on the surface of the tissue.
Association between Mutation Spectra and Stable and Unstable DNA Adduct Profiles in Salmonella for Benzo[a]pyrene and Dibenzo[a.l]pyrene

EPA Science Inventory

Benzo[a]pyrene (BP) and dibenzo[a,l]pyrene (DBP) are two polycyclic aromatic hydrocarbons (PAHs) that exhibit distinctly different mutagenicity and carcinogenicity profiles. Although some studies show that these PAHs produce unstable DNA adducts, conflicting data and arguments ha...
Phase Behavior of Pyrene and Vinyl Polymers with Aromatic Side Groups

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kangovi, Gagan N.; Lee, Sangwoo

The phase behavior and thermodynamic properties of mixtures of pyrene and model vinyl polymers with and without aromatic side groups are investigated using differential scanning calorimetry (DSC) measurements. The melting temperature and associated heat of melting of the pyrene crystals in the mixtures are utilized to extract the effective interaction parameters χ and the composition of polymer-rich phases, respectively. The χ of pyrene mixed with polymers with aromatic side groups investigated in this study, polystyrene, poly(2-vinylpyridine), and poly(3-vinylanisole), is less than 0.5 at the melting point of the pyrene crystals, suggesting that pyrene and the polymers with aromatic sides groupsmore » are enthalpically compatible, likely due to aromatic π–π interactions. In contrast, the χ of pyrene mixed with poly(1,4-isoprene) or poly(ethylene-alt-propylene) is larger than 0.5. The DSC measurements also enable characterization of the composition of polymer-rich phases. Interestingly, the polymers with aromatic side groups are found to have more pronounced miscibility with pyrene at symmetric compositions.« less
Detection of experimental brain tumors using time-resolved laser-induced fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Thompson, Reid C.; Black, Keith L.; Kateb, Babak; Marcu, Laura

2002-05-01

Time-Resolved Laser-Induced Fluorescence Spectroscopy (TR-LIFS) has the potential to provide a non- invasive characterization and detection of tumors. We utilized TR-LIFS to detect gliomas in-vivo in the rat C6 glioma model. Time-resolved emission spectra of both normal brain and tumor were analyzed to determine if unique fluorescence signatures could be used to distinguish the two. Fluorescence parameters derived from both spectral and time domain were used for tissue characterization. Our results show that in the rat C6 glioma model, TR-LIFS can be used to differentiate brain tumors from normal tissue (gray and white mater) based upon time- resolved fluorescence signatures seen in brain tumors.
Depth-resolved fluorescence of biological tissue

NASA Astrophysics Data System (ADS)

Wu, Yicong; Xi, Peng; Cheung, Tak-Hong; Yim, So Fan; Yu, Mei-Yung; Qu, Jianan Y.

2005-06-01

The depth-resolved autofluorescence ofrabbit oral tissue, normal and dysplastic human ectocervical tissue within l20μm depth were investigated utilizing a confocal fluorescence spectroscopy with the excitations at 355nm and 457nm. From the topmost keratinizing layer of oral and ectocervical tissue, strong keratin fluorescence with the spectral characteristics similar to collagen was observed. The fluorescence signal from epithelial tissue between the keratinizing layer and stroma can be well resolved. Furthermore, NADH and FADfluorescence measured from the underlying non-keratinizing epithelial layer were strongly correlated to the tissue pathology. This study demonstrates that the depth-resolved fluorescence spectroscopy can reveal fine structural information on epithelial tissue and potentially provide more accurate diagnostic information for determining tissue pathology.
Noninvasive control of rhodamine-loaded capsules distribution in vivo

NASA Astrophysics Data System (ADS)

Stelmashchuk, O.; Tarakanchikova, Y.; Seryogina, E.; Piavchenko, G.; Zherebtsov, E.; Dunaev, A.; Popov, A.; Meglinski, I.

2018-04-01

Using fluorescence spectroscopy system with fibre-optical probe, we investigated the dynamics of propagation and circulation in the microcirculatory system of experimental nanocapsules fluorescent-labelled (rhodamine TRITC) nanocapsules. The studies were carried out in clinically healthy Wistar rats. The model animals were divided into control group and group received injections of the nanocapsules. The fluorescent measurements conducted transcutaneously on the thigh surface. The administration of the preparation with the rhodamine concentration of 5 mg/kg of animal weight resulted in twofold increase of fluorescence intensity by reference to the baseline level. As a result of the study, it was concluded that fluorescence spectroscopy can be used for transdermal measurements of the rhodamine-loaded capsules in vivo.
Synthesis and characterization of ZnS@Fe3O4 fluorescent-magnetic bifunctional nanospheres

NASA Astrophysics Data System (ADS)

Koc, Kenan; Karakus, Baris; Rajar, Kausar; Alveroglu, Esra

2017-10-01

Herein, we synthesized and characterized fluorescent and super paramagnetic ZnS@Fe3O4 nanospheres. First, (3-mercaptopropyl) trimethoxysilane (MPS) capped ZnS quantum dots (QDs) and SiO2 coated Fe3O4 nanoparticles were synthesized separately by using solution growth and co-precipitation techniques. After synthesis and characterization of these two nanoparticles, they were conglutinated together in a nano sized sphere. The QDs were attached to the surface of the Fe3O4 nanoparticles by Sisbnd Osbnd Si bonds and so Sisbnd Osbnd Si bonds created a SiO2 network around the nanoparticles during the formation of the ZnS@Fe3O4 nanospheres. The synthesized MPS capped ZnS fluorescent QDs, SiO2 coated magnetite super paramagnetic nanoparticles and ZnS@Fe3O4 fluorescent-magnetic bifunctional nanospheres were characterized by using UV-Vis Absorption Spectroscopy, Fluorescence Spectroscopy, X-ray analysis, Vibrating Sample Magnetometer analysis, Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy, Scanning Electron Microscope and Energy-dispersive X-ray spectroscopy. ZnS@Fe3O4 bifunctional nanospheres were shown to retain the magnetic properties of magnetite, while exhibiting the luminescent optical properties of ZnS nanoparticles. The combination of fluorescent and magnetic behaviors of nano composites make them useful for potential applications in the field of bio-medical and environmental.
In vivo quantification of chromophore concentration using fluorescence differential path length spectroscopy

NASA Astrophysics Data System (ADS)

Kruijt, Bastiaan; Kascakova, Slavka; de Bruijn, Henriette S.; van der Ploeg-van den Heuvel, Angelique; Sterenborg, Henricus J. C. M.; Robinson, Dominic J.; Amelink, Arjen

2009-05-01

We present an optical method based on fluorescence spectroscopy for measuring chromophore concentrations in vivo. Fluorescence differential path length spectroscopy (FPDS) determines chromophore concentration based on the fluorescence intensity corrected for absorption. The concentration of the photosensitizer m-THPC (Foscan®) was studied in vivo in normal rat liver, which is highly vascularized and therefore highly absorbing. Concentration estimates of m-THPC measured by FDPS on the liver are compared with chemical extraction. Twenty-five rats were injected with 0.3 mg/kg m-THPC. In vivo optical concentration measurements were performed on tissue 3, 24, 48, and 96 h after m-THPC administration to yield a 10-fold variation in tissue concentration. After the optical measurements, the liver was harvested for chemical extraction. FDPS showed good correlation with chemical extraction. FDPS also showed a correlation between m-THPC fluorescence and blood volume fraction at the two shortest drug-light intervals. This suggests different compartmental localization of m-THPC for different drug-light intervals that can be resolved using fluorescence spectroscopy. Differences in measured m-THPC concentration between FDPS and chemical extraction are related to the interrogation volume of each technique; ~0.2 mm3 and ~102 mm3, respectively. This indicates intra-animal variation in m-THPC distribution in the liver on the scale of the FDPS sampling volume.
Diiodobodipy-styrylbodipy Dyads: Preparation and Study of the Intersystem Crossing and Fluorescence Resonance Energy Transfer.

PubMed

Wang, Zhijia; Xie, Yun; Xu, Kejing; Zhao, Jianzhang; Glusac, Ksenija D

2015-07-02

2,6-Diiodobodipy-styrylbodipy dyads were prepared to study the competing intersystem crossing (ISC) and the fluorescence-resonance-energy-transfer (FRET), and its effect on the photophysical property of the dyads. In the dyads, 2,6-diiodobodipy moiety was used as singlet energy donor and the spin converter for triplet state formation, whereas the styrylbodipy was used as singlet and triplet energy acceptors, thus the competition between the ISC and FRET processes is established. The photophysical properties were studied with steady-state UV-vis absorption and fluorescence spectroscopy, electrochemical characterization, and femto/nanosecond time-resolved transient absorption spectroscopies. FRET was confirmed with steady state fluorescence quenching and fluorescence excitation spectra and ultrafast transient absorption spectroscopy (kFRET = 5.0 × 10(10) s(-1)). The singlet oxygen quantum yield (ΦΔ = 0.19) of the dyad was reduced as compared with that of the reference spin converter (2,6-diiodobodipy, ΦΔ = 0.85), thus the ISC was substantially inhibited by FRET. Photoinduced intramolecular electron transfer (ET) was studied by electrochemical data and fluorescence quenching. Intermolecular triplet energy transfer was studied with nanosecond transient absorption spectroscopy as an efficient (ΦTTET = 92%) and fast process (kTTET = 5.2 × 10(4) s(-1)). These results are useful for designing organic triplet photosensitizers and for the study of the photophysical properties.
Rapid Mineralization of Benzo[a]pyrene by a Microbial Consortium Growing on Diesel Fuel

PubMed Central

Kanaly, Robert A.; Bartha, Richard; Watanabe, Kazuya; Harayama, Shigeaki

2000-01-01

A microbial consortium which rapidly mineralized the environmentally persistent pollutant benzo[a]pyrene was recovered from soil. The consortium cometabolically converted [7-14C]benzo[a]pyrene to 14CO2 when it was grown on diesel fuel, and the extent of benzo[a]pyrene mineralization was dependent on both diesel fuel and benzo[a]pyrene concentrations. Addition of diesel fuel at concentrations ranging from 0.007 to 0.2% (wt/vol) stimulated the mineralization of 10 mg of benzo[a]pyrene per liter 33 to 65% during a 2-week incubation period. When the benzo[a]pyrene concentration was 10 to 100 mg liter−1 and the diesel fuel concentration was 0.1% (wt/vol), an inoculum containing 1 mg of cell protein per liter (small inoculum) resulted in mineralization of up to 17.2 mg of benzo[a]pyrene per liter in 16 days. This corresponded to 35% of the added radiolabel when the concentration of benzo[a]pyrene was 50 mg liter−1. A radiocarbon mass balance analysis recovered 25% of the added benzo[a]pyrene solubilized in the culture suspension prior to mineralization. Populations growing on diesel fuel most likely promoted emulsification of benzo[a]pyrene through the production of surface-active compounds. The consortium was also analyzed by PCR-denaturing gradient gel electrophoresis of 16S rRNA gene fragments, and 12 dominant bands, representing different sequence types, were detected during a 19-day incubation period. The onset of benzo[a]pyrene mineralization was compared to changes in the consortium community structure and was found to correlate with the emergence of at least four sequence types. DNA from 10 sequence types were successfully purified and sequenced, and that data revealed that eight of the consortium members were related to the class Proteobacteria but that the consortium also included members which were related to the genera Mycobacterium and Sphingobacterium. PMID:11010861
Planetary Surface Exploration Using Raman Spectroscopy on Rovers and Landers

NASA Astrophysics Data System (ADS)

Blacksberg, Jordana; Alerstam, E.; Maruyama, Y.; Charbon, E.; Rossman, G. R.

2013-10-01

Planetary surface exploration using laser induced breakdown spectroscopy (LIBS) to probe the composition of rocks has recently become a reality with the operation of the mast-mounted ChemCam instrument onboard the Curiosity rover. Following this success, Raman spectroscopy has steadily gained support as a means for using laser spectroscopy to identify not just composition but mineral phases, without the need for sample preparation. The RLS Raman Spectrometer is included on the payload for the ExoMars mission, and a Raman spectrometer has been included in an example strawman payload for NASA’s Mars 2020 mission. Raman spectroscopy has been identified by the community as a feasible means for pre-selection of samples on Mars for subsequent return to Earth. We present a next-generation instrument that builds on the widely used green-Raman technique to provide a means for performing Raman spectroscopy without the background noise that is often generated by fluorescence of minerals and organics. Microscopic Raman spectroscopy with a laser spot size smaller than the grains of interest can provide surface mapping of mineralogy while preserving morphology. A very small laser spot size 1 µm) is often necessary to identify minor phases that are often of greater interest than the matrix phases. In addition to the difficulties that can be posed by fine-grained material, fluorescence interference from the very same material is often problematic. This is particularly true for many of the minerals of interest that form in environments of aqueous alteration and can be highly fluorescent. We use time-resolved laser spectroscopy to eliminate fluorescence interference that can often make it difficult or impossible to obtain Raman spectra. We will discuss significant advances leading to the feasibility of a compact time-resolved spectrometer, including the development of a new solid-state detector capable of sub-ns time resolution. We will present results on planetary analog minerals to demonstrate the instrument performance including fluorescence rejection.
Quantification of tumor fluorescence during intraoperative optical cancer imaging.

PubMed

Judy, Ryan P; Keating, Jane J; DeJesus, Elizabeth M; Jiang, Jack X; Okusanya, Olugbenga T; Nie, Shuming; Holt, David E; Arlauckas, Sean P; Low, Phillip S; Delikatny, E James; Singhal, Sunil

2015-11-13

Intraoperative optical cancer imaging is an emerging technology in which surgeons employ fluorophores to visualize tumors, identify tumor-positive margins and lymph nodes containing metastases. This study compares instrumentation to measure tumor fluorescence. Three imaging systems (Spectropen, Glomax, Flocam) measured and quantified fluorescent signal-to-background ratios (SBR) in vitro, murine xenografts, tissue phantoms and clinically. Evaluation criteria included the detection of small changes in fluorescence, sensitivity of signal detection at increasing depths and practicality of use. In vitro, spectroscopy was superior in detecting incremental differences in fluorescence than luminescence and digital imaging (Ln[SBR] = 6.8 ± 0.6, 2.4 ± 0.3, 2.6 ± 0.1, p = 0.0001). In fluorescent tumor cells, digital imaging measured higher SBRs than luminescence (6.1 ± 0.2 vs. 4.3 ± 0.4, p = 0.001). Spectroscopy was more sensitive than luminometry and digital imaging in identifying murine tumor fluorescence (SBR = 41.7 ± 11.5, 5.1 ± 1.8, 4.1 ± 0.9, p = 0.0001), and more sensitive than digital imaging at detecting fluorescence at increasing depths (SBR = 7.0 ± 3.4 vs. 2.4 ± 0.5, p = 0.03). Lastly, digital imaging was the most practical and least time-consuming. All methods detected incremental differences in fluorescence. Spectroscopy was the most sensitive for small changes in fluorescence. Digital imaging was the most practical considering its wide field of view, background noise filtering capability, and sensitivity to increasing depth.
ADDITIVITY OF IN VIVO MUTATION INDUCTION BY CUMULATIVE EXPOSURES TO BENZO[A]PYRENE OR DIBENZO[A,L]PYRENE

EPA Science Inventory

Dibenzo[a,l]pyrene (DB[a,l]P) and benzo[a]pyrene (B[a]P) are polycyclic aromatic hydrocarbons (PAH) found in cigarette smoke condensate, coal combustion processes and in some environmental pollutants. In this study, we investigated the effect of dosing regimen on the mutagenicity...
Using resonance light scattering and UV/vis absorption spectroscopy to study the interaction between gliclazide and bovine serum albumin.

PubMed

Zhang, Qiu-Ju; Liu, Bao-Sheng; Li, Gai-Xia; Han, Rong

2016-08-01

At different temperatures (298, 310 and 318 K), the interaction between gliclazide and bovine serum albumin (BSA) was investigated using fluorescence quenching spectroscopy, resonance light scattering spectroscopy and UV/vis absorption spectroscopy. The first method studied changes in the fluorescence of BSA on addition of gliclazide, and the latter two methods studied the spectral change in gliclazide while BSA was being added. The results indicated that the quenching mechanism between BSA and gliclazide was static. The binding constant (Ka ), number of binding sites (n), thermodynamic parameters, binding forces and Hill's coefficient were calculated at three temperatures. Values for the binding constant obtained using resonance light scattering and UV/vis absorption spectroscopy were much greater than those obtained from fluorescence quenching spectroscopy, indicating that methods monitoring gliclazide were more accurate and reasonable. In addition, the results suggest that other residues are involved in the reaction and the mode 'point to surface' existed in the interaction between BSA and gliclazide. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.
Approaches to Measuring Entanglement in Chemical Magnetometers

PubMed Central

2013-01-01

Chemical magnetometers are radical pair systems such as solutions of pyrene and N,N-dimethylaniline (Py–DMA) that show magnetic field effects in their spin dynamics and their fluorescence. We investigate the existence and decay of quantum entanglement in free geminate Py–DMA radical pairs and discuss how entanglement can be assessed in these systems. We provide an entanglement witness and propose possible observables for experimentally estimating entanglement in radical pair systems with isotropic hyperfine couplings. As an application, we analyze how the field dependence of the entanglement lifetime in Py–DMA could in principle be used for magnetometry and illustrate the propagation of measurement errors in this approach. PMID:24372396
Laser-Induced Fluorescence Emission (L.I.F.E.): searching for Mars organics with a UV-enhanced PanCam.

PubMed

Storrie-Lombardi, Michael C; Muller, Jan-Peter; Fisk, Martin R; Cousins, Claire; Sattler, Birgit; Griffiths, Andrew D; Coates, Andrew J

2009-12-01

The European Space Agency will launch the ExoMars mission in 2016 with a primary goal of surveying the martian subsurface for evidence of organic material. We have recently investigated the utility of including either a 365 nm light-emitting diode or a 375 nm laser light source in the ExoMars rover panoramic camera (PanCam). Such a modification would make it feasible to monitor rover drill cuttings optically for the fluorescence signatures of aromatic organic molecules and map the distribution of polycyclic aromatic hydrocarbons (PAHs) as a function of depth to the 2 m limit of the ExoMars drill. The technique described requires no sample preparation, does not consume irreplaceable resources, and would allow mission control to prioritize deployment of organic detection experiments that require sample destruction, expenditure of non-replaceable consumables, or both. We report here for the first time laser-induced fluorescence emission (L.I.F.E.) imaging detection limits for anthracene, pyrene, and perylene targets doped onto a Mars analog granular peridotite with a 375 nm Nichia laser diode in optically uncorrected wide-angle mode. Data were collected via the Beagle 2 PanCam backup filter wheel fitted with original blue (440 nm), green (530 nm), and red (670 nm) filters. All three PAH species can be detected with the PanCam green (530 nm) filter. Detection limits in the green band for signal-to-noise ratios (S/N) > 10 are 49 parts per million (ppm) for anthracene, 145 ppm for pyrene, and 20 ppm for perylene. The anthracene detection limit improves to 7 ppm with use of the PanCam blue filter. We discuss soil-dependent detection limit constraints; use of UV excitation with other rover cameras, which provides higher spatial resolution; and the advantages of focused and wide-angle laser modes. Finally, we discuss application of L.I.F.E. techniques at multiple wavelengths for exploration of Mars analog extreme environments on Earth, including Icelandic hydrothermally altered basalts and the ice-covered lakes and glaciers of Dronning Maud Land, Antarctica.

Feasibility of Raman spectroscopy in vitro after 5-ALA-based fluorescence diagnosis in the bladder

NASA Astrophysics Data System (ADS)

Grimbergen, M. C. M.; van Swol, C. F. P.; van Moorselaar, R. J. A.; Mahadevan-Jansen, A.,; Stone, N.

2006-02-01

Photodynamic diagnosis (PDD) has become popular in bladder cancer detection. Several studies have however shown an increased false positive biopsies rate under PDD guidance compared to conventional cystoscopy. Raman spectroscopy is an optical technique that utilizes molecular specific, inelastic scattering of light photons to interrogate biological tissues, which can successfully differentiate epithelial neoplasia from normal tissue and inflammations in vitro. This investigation was performed to show the feasibility of NIR Raman spectroscopy in vitro on biopsies obtained under guidance of 5-ALA induced PPIX fluorescence imaging. Raman spectra of a PPIX solution was measured to obtain a characteristic signature for the photosensitzer without contributions from tissue constituents. Biopsies were obtained from patients with known bladder cancer instilled with 50ml, 5mg 5-ALA two hours prior to trans-urethral resection of tumor (TURT). Additional biopsies were obtained at a fluorescent and non-fluorescent area, snap-frozen in liquid nitrogen and stored at -80 °C. Each biopsy was thawed before measurements (10sec integration time) with a confocal Raman system (Renishaw Gloucestershire, UK). The 830 nm excitation (300mW) source is focused on the tissue by a 20X ultra-long-working-distance objective. Differences in fluorescence background between the two groups were removed by means of a special developed fluorescence subtraction algorithm. Raman spectra from ALA biopsies showed different fluorescence background which can be effectively removed by a fluorescence subtraction algorithm. This investigation shows that the interaction of the ALA induced PPIX with Raman spectroscopy in bladder samples. Combination of these techniques in-vivo may lead to a viable method of optical biopsies in bladder cancer detection.
Two-dimensional fluorescence correlation spectroscopy: resolution of fluorescence of tryptophan residues in horse heart myoglobin.

PubMed

Nakashima, Kenichi; Yuda, Kazuki; Ozaki, Yukihiro; Noda, Isao

2003-11-01

Generalized two-dimensional (2D) fluorescence correlation spectroscopy has been used to resolve fluorescence of two tryptophan (Trp) residues in horse heart myoglobin. Fluorescence quenching is employed as a perturbation mode for causing intensity changes in the fluorescence (quenching perturbation). Two kinds of quenchers, iodide ion and acrylamide, are used for inducing fluorescence intensity change. This technique works because the Trp residue located at the 7th position (W7) is known to be easily accessible to the quencher, whereas that located at the 14th position (W14) is not. By this technique, the fluorescence spectra of the two Trp residues were clearly resolved. From asynchronous maps, it was also shown that the quenching of W7 fluorescence is brought about prior to the quenching of W14 fluorescence. This result is consistent with the structure of horse heart myoglobin that was proposed earlier. Furthermore, it was elucidated that the present 2D analysis is not interfered with by Raman bands of the solvents, which sometimes brings difficulty into conventional fluorescence analysis.
"FluSpec": A Simulated Experiment in Fluorescence Spectroscopy

ERIC Educational Resources Information Center

Bigger, Stephen W.; Bigger, Andrew S.; Ghiggino, Kenneth P.

2014-01-01

The "FluSpec" educational software package is a fully contained tutorial on the technique of fluorescence spectroscopy as well as a simulator on which experiments can be performed. The procedure for each of the experiments is also contained within the package along with example analyses of results that are obtained using the software.
Non-destructive NIR-FT-Raman spectroscopy of plant and animal tissues, of food and works of art.

PubMed

Schrader, B; Schulz, H; Andreev, G N; Klump, H H; Sawatzki, J

2000-10-02

Just after the discovery of Raman spectroscopy in 1928, it became evident that fluorescence with a quantum yield of several orders of magnitude higher than that of the Raman effect was a great and apparently unbeatable competitor. Raman spectroscopy could therefore, in spite of many exciting advantages during the last 60 years, not be applied as an analytical routine method: for nearly every sample, fluorescing impurities had to be removed by distillation or crystallisation. Purification, however, is not possible for cells and tissues, since the removal of the fluorescing enzymes and coenzymes would destroy the cells. There is fortunately one alternative solution. When excited with the radiation of the Nd:YAG laser at 1064 nm Raman spectra are practically free of fluorescence. Raman spectra can now be recorded with minimal sample preparation. In order to facilitate non-destructive Raman spectroscopy of any sample, cells and tissues, food, textiles and works of art, a new entrance optics for Raman spectrometers is used. Typical results from several fields are demonstrated.
The use of a multi-method approach to identify the pigments in the 12th century manuscript Liber Floridus

NASA Astrophysics Data System (ADS)

Deneckere, A.; De Reu, M.; Martens, M. P. J.; De Coene, K.; Vekemans, B.; Vincze, L.; De Maeyer, Ph.; Vandenabeele, P.; Moens, L.

2011-10-01

A selection of illuminations of the 12th century manuscript Liber Floridus was analysed with Raman spectroscopy (in situ and laboratory measurements), X-ray fluorescence spectroscopy, UV-fluorescence photography and infrared reflectography (IRR). The aim of this study is to determine the pigments used, in order to search for anachronisms. Using a combination of Raman spectroscopy (molecular information) and X-ray fluorescence spectroscopy (elemental information) following pigments could be identified: ultramarine (Na 8-10Al 6Si 6O 24S 2-4), azurite (2CuCO 3·Cu(OH) 2), caput mortuum (Fe 2O 3), vermilion (HgS), orpiment (As 2S 3) and lead white (2PbCO 3·Pb(OH) 2). Moreover, two synthetic red pigments, PR4 and PR176, and a degradation product, gypsum (CaSO 4·2H 2O), were present in the manuscript. To establish the origin of the modern materials UV-fluorescence photography was used. Infrared reflectography (IRR) was applied to visualise the underdrawing of the investigated folios.
Fluorescence spectroscopy and molecular weight distribution of extracellular polymers from full-scale activated sludge biomass.

PubMed

Esparza-Soto, M; Westerhoff, P K

2001-01-01

Two fractions of extracellular polymer substances (EPSs), soluble and readily extractable (RE), were characterised in terms of their molecular weight distributions (MWD) and 3-D excitation-emission-matrix (EEM) fluorescence spectroscopy signatures. The EPS fractions were different: the soluble EPSs were composed mainly of high molecular weight compounds, while the RE EPSs were composed of small molecular weight compounds. Contrary to previous thought, EPS may not be considered only as macromolecular because most organic matter present in both fractions had low molecular weight. Three different fluorophore peaks were identified in the EEM fluorescence spectra. Two peaks were attributed to protein-like fluorophores, and the third to a humic-like fluorophore. Fluorescence signatures were different from other previously published signatures for marine and riverine environments. EEM spectroscopy proved to be a suitable method that may be used to characterise and trace organic matter of bacterial origin in wastewater treatment operations.
Branched multifunctional polyether polyketals: variation of ketal group structure enables unprecedented control over polymer degradation in solution and within cells.

PubMed

Shenoi, Rajesh A; Narayanannair, Jayaprakash K; Hamilton, Jasmine L; Lai, Benjamin F L; Horte, Sonja; Kainthan, Rajesh K; Varghese, Jos P; Rajeev, Kallanthottathil G; Manoharan, Muthiah; Kizhakkedathu, Jayachandran N

2012-09-12

Multifunctional biocompatible and biodegradable nanomaterials incorporating specific degradable linkages that respond to various stimuli and with defined degradation profiles are critical to the advancement of targeted nanomedicine. Herein we report, for the first time, a new class of multifunctional dendritic polyether polyketals containing different ketal linkages in their backbone that exhibit unprecedented control over degradation in solution and within the cells. High-molecular-weight and highly compact poly(ketal hydroxyethers) (PKHEs) were synthesized from newly designed α-epoxy-ω-hydroxyl-functionalized AB(2)-type ketal monomers carrying structurally different ketal groups (both cyclic and acyclic) with good control over polymer properties by anionic ring-opening multibranching polymerization. Polymer functionalization with multiple azide and amine groups was achieved without degradation of the ketal group. The polymer degradation was controlled primarily by the differences in the structure and torsional strain of the substituted ketal groups in the main chain, while for polymers with linear (acyclic) ketal groups, the hydrophobicity of the polymer may play an additional role. This was supported by the log P values of the monomers and the hydrophobicity of the polymers determined by fluorescence spectroscopy using pyrene as the probe. A range of hydrolysis half-lives of the polymers at mild acidic pH values was achieved, from a few minutes to a few hundred days, directly correlating with the differences in ketal group structures. Confocal microscopy analyses demonstrated similar degradation profiles for PKHEs within live cells, as seen in solution and the delivery of fluorescent marker to the cytosol. The cell viability measured by MTS assay and blood compatibility determined by complement activation, platelet activation, and coagulation assays demonstrate that PKHEs and their degradation products are highly biocompatible. Taken together, these data demonstrate the utility this new class of biodegradable polymer as a highly promising candidate in the development of multifunctional nanomedicine.
Pyrene degradation by yeasts and filamentous fungi.

PubMed

Romero, M Cristina; Salvioli, Mónica L; Cazau, M Cecilia; Arambarri, A M

2002-01-01

The saprotrophic soil fungi Fusarium solani (Mart.) Sacc., Cylindrocarpon didymum (Hartig) Wollenw, Penicillium variabile Sopp. and the yeasts Rhodotorula glutinis (Fresenius) Harrison and Rhodotorula minuta (Saito) Harrison were cultured in mineral medium with pyrene. The remaining pyrene concentrations were periodically determined during 20 incubation days, using HPLC. To assess the metabolism of pyrene degradation we added 0.1 microCi of [4,5,9,10] 14C-pyrene to each fungi culture and measured the radioactivity in the volatile organic substances, extractable, aqueous phase, biomass and 14CO2 fractions. The assays demonstrated that F. solani and R. glutinis metabolized pyrene as a sole source of carbon. Differences in their activities at the beginning of the cultures disappeared by the end of the experiment, when 32 and 37% of the original pyrene concentration was detected, for the soil fungi and yeasts, respectively. Among the filamentous fungi, F. solani was highly active and oxidized pyrene; moreover, small but significant degradation rates were observed in C. didymum and P. variahile cultures. An increase in the 14CO2 evolution was observed at the 17th day with cosubstrate. R. glutinis and R. minuta cultures showed similar ability to biotransform pyrene, and that 35% of the initial concentration was consumed at the end of the assay. The same results were obtained in the experiments with or without glucose as cosubstrate.
Intraoperative near-infrared fluorescence imaging and spectroscopy identifies residual tumor cells in wounds

NASA Astrophysics Data System (ADS)

Holt, David; Parthasarathy, Ashwin B.; Okusanya, Olugbenga; Keating, Jane; Venegas, Ollin; Deshpande, Charuhas; Karakousis, Giorgos; Madajewski, Brian; Durham, Amy; Nie, Shuming; Yodh, Arjun G.; Singhal, Sunil

2015-07-01

Surgery is the most effective method to cure patients with solid tumors, and 50% of all cancer patients undergo resection. Local recurrences are due to tumor cells remaining in the wound, thus we explore near-infrared (NIR) fluorescence spectroscopy and imaging to identify residual cancer cells after surgery. Fifteen canines and two human patients with spontaneously occurring sarcomas underwent intraoperative imaging. During the operation, the wounds were interrogated with NIR fluorescence imaging and spectroscopy. NIR monitoring identified the presence or absence of residual tumor cells after surgery in 14/15 canines with a mean fluorescence signal-to-background ratio (SBR) of ˜16. Ten animals showed no residual tumor cells in the wound bed (mean SBR<2, P<0.001). None had a local recurrence at >1-year follow-up. In five animals, the mean SBR of the wound was >15, and histopathology confirmed tumor cells in the postsurgical wound in four/five canines. In the human pilot study, neither patient had residual tumor cells in the wound bed, and both remain disease free at >1.5-year follow up. Intraoperative NIR fluorescence imaging and spectroscopy identifies residual tumor cells in surgical wounds. These observations suggest that NIR imaging techniques may improve tumor resection during cancer operations.
Double optical fibre-probe device for the diagnosis of melanocytic lesions

NASA Astrophysics Data System (ADS)

Cicchi, Riccardo; Cosci, Alessandro; Rossari, Susanna; De Giorgi, Vincenzo; Kapsokalyvas, Dimitrios; Massi, Daniela; Pavone, Francesco S.

2012-06-01

We have designed and developed an optical fiber-probe for spectroscopic measurements on human tissues. The experimental setup combines fluorescence spectroscopy and Raman spectroscopy in a multidimensional approach. Concerning fluorescence spectroscopy, the excitation is provided by two laser diodes, one emitting in the UV (378 nm) and the other emitting in the visible (445 nm). These two lasers are used to selectively excite fluorescence from NADH and FAD, which are among the brightest endogenous fluorophores in human tissues. For Raman and NIR spectroscopy, the excitation is provided by a third laser diode with 785 nm excitation wavelength. Laser light is delivered to the tissue through the central optical fiber of a fiber bundle. The surrounding 48 fibers of the bundle are used for collecting fluorescence and Raman and for delivering light to the spectrograph. Fluorescence and Raman spectra are acquired on a cooled CCD camera. The instrument has been tested on fresh human skin biopsies clinically diagnosed as malignant melanoma, melanocytic nevus, or healthy skin, finding an optimal correlation with the subsequent histological exam. In some cases our examination was not in agreement with the clinical observation, but it was with the histological exam, demonstrating that the system can potentially contribute to improve clinical diagnostic capabilities and hence reduce the number of unnecessary biopsies.
Intraoperative near-infrared fluorescence imaging and spectroscopy identifies residual tumor cells in wounds

PubMed Central

Holt, David; Parthasarathy, Ashwin B.; Okusanya, Olugbenga; Keating, Jane; Venegas, Ollin; Deshpande, Charuhas; Karakousis, Giorgos; Madajewski, Brian; Durham, Amy; Nie, Shuming; Yodh, Arjun G.; Singhal, Sunil

2015-01-01

Abstract. Surgery is the most effective method to cure patients with solid tumors, and 50% of all cancer patients undergo resection. Local recurrences are due to tumor cells remaining in the wound, thus we explore near-infrared (NIR) fluorescence spectroscopy and imaging to identify residual cancer cells after surgery. Fifteen canines and two human patients with spontaneously occurring sarcomas underwent intraoperative imaging. During the operation, the wounds were interrogated with NIR fluorescence imaging and spectroscopy. NIR monitoring identified the presence or absence of residual tumor cells after surgery in 14/15 canines with a mean fluorescence signal-to-background ratio (SBR) of ∼16. Ten animals showed no residual tumor cells in the wound bed (mean SBR<2, P<0.001). None had a local recurrence at >1-year follow-up. In five animals, the mean SBR of the wound was >15, and histopathology confirmed tumor cells in the postsurgical wound in four/five canines. In the human pilot study, neither patient had residual tumor cells in the wound bed, and both remain disease free at >1.5-year follow up. Intraoperative NIR fluorescence imaging and spectroscopy identifies residual tumor cells in surgical wounds. These observations suggest that NIR imaging techniques may improve tumor resection during cancer operations. PMID:26160347
Complementary use of optical coherence tomography and 5-aminolevulinic acid induced fluorescent spectroscopy for diagnosis of neoplastic processes in cervix and vulva

NASA Astrophysics Data System (ADS)

Sapozhnikova, Veronika V.; Shakhova, Natalia M.; Kamensky, Vladislav A.; Kuranov, Roman V.; Loshenov, Victor B.; Petrova, Svetlana A.

2003-07-01

A new approach to improving the diagnostic value of optical methods is suggested, which is based on a complementary investigation of different optical parameters of biotissues. The aim of this paper is comparative study of the feasibility of two optical methods - fluorescence spectroscopy and optical coherence tomography - for visualization of borders of neoplastic processes in the uterine cervix and vulva. Fluorescence spectroscopy is based on the detection of biochemical and optical coherence tomography on backscattering properties in norm and pathological changes of tissues. By means of these optical methods changes in biochemical and morphological properties of tissues were investigated. A parallel analysis of these two optical methods and histology from the center of tumors and their optical borders was made. Thirteen female patients with neoplastic changes in uterine cervix and vulva were enrolled in this study. The borders of the tumor determined by optical methods (fluorescence spectroscopy and optical coherence tomography) are coinciding with the biopsy proved ones. In addition, OCT and fluorescence borders of tumor in the uterine cervix and vulva exceeds colposcopically detectable borders, the averaging difference 2 mm. In future optical methods would considerably enhance diagnostic accuracy of conventional methods used in oncogynecology.
25 years and still going strong: 2'-O-(pyren-1-yl)methylribonucleotides - versatile building blocks for applications in molecular biology, diagnostics and materials science.

PubMed

Hrdlicka, Patrick J; Karmakar, Saswata

2017-11-29

Oligonucleotides (ONs) modified with 2'-O-(pyren-1-yl)methylribonucleotides have been explored for a range of applications in molecular biology, nucleic acid diagnostics, and materials science for more than 25 years. The first part of this review provides an overview of synthetic strategies toward 2'-O-(pyren-1-yl)methylribonucleotides and is followed by a summary of biophysical properties of nucleic acid duplexes modified with these building blocks. Insights from structural studies are then presented to rationalize the reported properties. In the second part, applications of ONs modified with 2'-O-(pyren-1-yl)methyl-RNA monomers are reviewed, which include detection of RNA targets, discrimination of single nucleotide polymorphisms, formation of self-assembled pyrene arrays on nucleic acid scaffolds, the study of charge transfer phenomena in nucleic acid duplexes, and sequence-unrestricted recognition of double-stranded DNA. The predictable binding mode of the pyrene moiety, coupled with the microenvironment-dependent properties and synthetic feasibility, render 2'-O-(pyren-1-yl)methyl-RNA monomers as a promising class of pyrene-functionalized nucleotide building blocks for new applications in molecular biology, nucleic acid diagnostics, and materials science.
Surface molecular imprinting onto fluorescein-coated magnetic nanoparticlesvia reversible addition fragmentation chain transfer polymerization: A facile three-in-one system for recognition and separation of endocrine disrupting chemicals

NASA Astrophysics Data System (ADS)

Li, Ying; Dong, Cunku; Chu, Jia; Qi, Jingyao; Li, Xin

2011-01-01

In this study, we present a general protocol for the making of surface-imprinted magnetic fluorescence beads viareversible addition-fragmentation chain transfer polymerization. The resulting composites were characterized by X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The as-synthesized beads exhibited homogeneous polymer films (thickness of about 5.7 nm), spherical shape, high fluorescence intensity and magnetic property (Magnetization (Ms) = 3.67 emu g-1). The hybrids bind the original template 17β-estradiol with an appreciable selectivity over structurally related compounds. In addition, the resulting hybrids performed without obvious deterioration after five repeated cycles. This study therefore demonstrates the potential of molecularly imprinted polymers for the recognition and separation of endocrine disrupting chemicals.In this study, we present a general protocol for the making of surface-imprinted magnetic fluorescence beads viareversible addition-fragmentation chain transfer polymerization. The resulting composites were characterized by X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The as-synthesized beads exhibited homogeneous polymer films (thickness of about 5.7 nm), spherical shape, high fluorescence intensity and magnetic property (Magnetization (Ms) = 3.67 emu g-1). The hybrids bind the original template 17β-estradiol with an appreciable selectivity over structurally related compounds. In addition, the resulting hybrids performed without obvious deterioration after five repeated cycles. This study therefore demonstrates the potential of molecularly imprinted polymers for the recognition and separation of endocrine disrupting chemicals. Electronic supplementary information (ESI) available: Supplementary figure S1. The hysteresis loop of Fe3O4 (a), Fe3O4@SiO2 (b), and Fe3O4@SiO2-Dye-SiO2 (c). See DOI: 10.1039/c0nr00614a
Optical nonlinearity and charge transfer analysis of pyrene adsorbed on silver: Computational and experimental investigations

NASA Astrophysics Data System (ADS)

Reeta Felscia, U.; Rajkumar, Beulah J. M.; Sankar, Pranitha; Philip, Reji; Briget Mary, M.

2017-09-01

The interaction of pyrene on silver has been investigated using both experimental and computational methods. Hyperpolarizabilities computed theoretically together with experimental nonlinear absorption from open aperture Z-scan measurements, point towards a possible use of pyrene adsorbed on silver in the rational design of NLO devices. Presence of a red shift in both simulated and experimental UV-Vis spectra confirms the adsorption on silver, which is due to the electrostatic interaction between silver and pyrene, inducing variations in the structural parameters of pyrene. Fukui calculations along with MEP plot predict the electrophilic nature of the silver cluster in the presence of pyrene, with NBO analysis revealing that the adsorption causes charge redistribution from the first three rings of pyrene towards the fourth ring, from where the 2p orbitals of carbon interact with the valence 5s orbitals of the cluster. This is further confirmed by the downshifting of ring breathing modes in both the experimental and theoretical Raman spectra.
Use of fluorescence spectroscopy to control ozone dosage in recirculating aquaculture systems.

PubMed

Spiliotopoulou, Aikaterini; Martin, Richard; Pedersen, Lars-Flemming; Andersen, Henrik R

2017-03-15

The aim of this study was to investigate the potential of fluorescence spectroscopy to be used as an ozone dosage determination tool in recirculating aquaculture systems (RASs), by studying the relationship between fluorescence intensities and dissolved organic matter (DOM) degradation by ozone, in order to optimise ozonation treatment. Water samples from six different Danish facilities (two rearing units from a commercial trout RAS, a commercial eel RAS, a pilot RAS and two marine water aquariums) were treated with different O 3 dosages (1.0-20.0 mg/L ozone) in bench-scale experiments, following which fluorescence intensity degradation was eventually determined. Ozonation kinetic experiments showed that RAS water contains fluorescent organic matter, which is easily oxidised upon ozonation in relatively low concentrations (0-5 mg O 3 /L). Fluorescence spectroscopy has a high level of sensitivity and selectivity in relation to associated fluorophores, and it is able to determine accurately the ozone demand of each system. The findings can potentially be used to design offline or online sensors based on the reduction by ozone of natural fluorescent-dissolved organic matter in RAS. The suggested indirect determination of ozone delivered into water can potentially contribute to a safer and more adequate ozone-based treatment to improve water quality. Copyright © 2016 Elsevier Ltd. All rights reserved.
Validation of a time-resolved fluorescence spectroscopy apparatus in a rabbit atherosclerosis model

NASA Astrophysics Data System (ADS)

Fang, Qiyin; Jo, Javier A.; Papaioannou, Thanassis; Dorafshar, Amir; Reil, Todd; Qiao, Jian-Hua; Fishbein, Michael C.; Freischlag, Julie A.; Marcu, Laura

2004-07-01

Time-resolved laser-induced fluorescence spectroscopy (tr-LIFS) has been studied as a potential tool for in vivo diagnosis of atherosclerotic lesions. This study is to evaluate the potential of a compact fiber-optics based tr-LIFS instrument developed in our laboratory for in vivo analysis of atherosclerotic plaque composition. Time-resolved fluorescence spectroscopy studies were performed in vivo on fifteen New Zealand White rabbits (atherosclerotic: N=8, control: N=7). Time-resolved fluorescence spectra were acquired (range: 360-600 nm, increment: 5 nm, total acquisition time: 65 s) from normal aorta wall and lesions in the abdominal aorta. Data were analyzed in terms of fluorescence emission spectra and wavelength specific lifetimes. Following trichrome staining, tissue specimens were analyzed histopathologically in terms of intima/media thickness and biochemical composition (collagen, elastin, foam cells, and etc). Based on intimal thickness, the lesions were divided into thin and thick lesions. Each group was further separated into two categories: collagen rich lesions and foam cell rich lesions based on their biochemical composition. The obtained spectral and time domain fluorescence signatures were subsequently correlated to the histopathological findings. The results have shown that time-domain fluorescence spectral features can be used in vivo to separate atherosclerotic lesions from normal aorta wall as well discrimination within certain types of lesions.
Assessment of the unidentified organic matter fraction in fogwater using fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Valsaraj, K.; Birdwell, J.

2010-07-01

Dissolved organic matter (DOM) in fogwaters from southeastern Louisiana and central-eastern China has been characterized using excitation-emission matrix (EEM) fluorescence spectroscopy. The results demonstrate that fluorescence spectroscopy can be used to obtain a qualitative assessment of the large fraction of fogwater organic carbon (~40 - 80% by weight) that cannot be identified in terms of specific chemical compounds. The method has the principle advantage that it can be applied at natural abundance concentrations, thus eliminating the need for large sample volumes required to isolate DOM for characterization by other spectroscopic (NMR, FTIR) and chemical (elemental) analyses. It was anticipated that the fogwater organic matter fluorescence spectra would resemble those of surface and rain waters, containing peaks indicative of both humic substances and fluorescent amino acids. Humic- and protein-like fluorophores were observed in the fogwater spectra and fluorescence-derived indices had values comparable to other natural waters. Biological character (intensity of tyrosine and tryptophan peaks) was found to increase with organic carbon concentration. Fogwater organic matter appears to contain a mixture of terrestrially- and microbially-derived material. The fluorescence results show that most of the unidentified fogwater organic carbon can be represented by humic-like and biologically-derived substances similar to those present in other aquatic systems.
Achieving second order advantage with multi-way partial least squares and residual bi-linearization with total synchronous fluorescence data of monohydroxy-polycyclic aromatic hydrocarbons in urine samples.

PubMed

Calimag-Williams, Korina; Knobel, Gaston; Goicoechea, H C; Campiglia, A D

2014-02-06

An attractive approach to handle matrix interference in samples of unknown composition is to generate second- or higher-order data formats and process them with appropriate chemometric algorithms. Several strategies exist to generate high-order data in fluorescence spectroscopy, including wavelength time matrices, excitation-emission matrices and time-resolved excitation-emission matrices. This article tackles a different aspect of generating high-order fluorescence data as it focuses on total synchronous fluorescence spectroscopy. This approach refers to recording synchronous fluorescence spectra at various wavelength offsets. Analogous to the concept of an excitation-emission data format, total synchronous data arrays fit into the category of second-order data. The main difference between them is the non-bilinear behavior of synchronous fluorescence data. Synchronous spectral profiles change with the wavelength offset used for sample excitation. The work presented here reports the first application of total synchronous fluorescence spectroscopy to the analysis of monohydroxy-polycyclic aromatic hydrocarbons in urine samples of unknown composition. Matrix interference is appropriately handled by processing the data either with unfolded-partial least squares and multi-way partial least squares, both followed by residual bi-linearization. Copyright © 2013 Elsevier B.V. All rights reserved.
The influence of local pressure on evaluation parameters of skin blood perfusion and fluorescence

NASA Astrophysics Data System (ADS)

Zherebtsov, E. A.; Kandurova, K. Y.; Seryogina, E. S.; Kozlov, I. O.; Dremin, V. V.; Zherebtsova, A. I.; Dunaev, A. V.; Meglinski, I.

2017-03-01

This article presents the results of the study of the pressure applied on optical diagnostic probes as a significant factor affecting the results of measurements. During stepwise increasing and decreasing of local pressure on skin we conducted measurements using the methods of laser Doppler flowmetry and fluorescence spectroscopy. It was found out that pressure on optical probe has sufficient impact on skin microcirculation to affect registered fluorescence intensity. Data obtained in this study are of interest for design and development of diagnostic technologies for wearable devices. This data will also inform further investigation into issues of compensation of blood absorption influence on fluorescence spectrum, allowing increased accuracy and reproducibility of measurements by fluorescence spectroscopy methods in optical diagnosis.

New approaches to the analysis of complex samples using fluorescence lifetime techniques and organized media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hertz, P.R.

Fluorescence spectroscopy is a highly sensitive and selective tool for the analysis of complex systems. In order to investigate the efficacy of several steady state and dynamic techniques for the analysis of complex systems, this work focuses on two types of complex, multicomponent samples: petrolatums and coal liquids. It is shown in these studies dynamic, fluorescence lifetime-based measurements provide enhanced discrimination between complex petrolatum samples. Additionally, improved quantitative analysis of multicomponent systems is demonstrated via incorporation of organized media in coal liquid samples. This research provides the first systematic studies of (1) multifrequency phase-resolved fluorescence spectroscopy for dynamic fluorescence spectralmore » fingerprinting of complex samples, and (2) the incorporation of bile salt micellar media to improve accuracy and sensitivity for characterization of complex systems. In the petroleum studies, phase-resolved fluorescence spectroscopy is used to combine spectral and lifetime information through the measurement of phase-resolved fluorescence intensity. The intensity is collected as a function of excitation and emission wavelengths, angular modulation frequency, and detector phase angle. This multidimensional information enhances the ability to distinguish between complex samples with similar spectral characteristics. Examination of the eigenvalues and eigenvectors from factor analysis of phase-resolved and steady state excitation-emission matrices, using chemometric methods of data analysis, confirms that phase-resolved fluorescence techniques offer improved discrimination between complex samples as compared with conventional steady state methods.« less
Study of anti-cancer effects of chemotherapeutic agents and radiotherapy in breast cancer patients using fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Chithra, K.; Vijayaraghavan, S.; Prakasarao, Aruna; Singaravelu, Ganesan

2017-02-01

The analysis of the variations in the spectroscopic patterns of the key bio molecules using Native fluorescence spectroscopy, without exogenous labels, has emerged as a new trend in the characterization of the Physiological State and the Discrimination of Pathological from normal conditions of cells and tissues as the relative concentration of these bio-molecules serve as markers in evaluating the presence of cancer in the body. The aim of this unique study is to use these features of Optical spectroscopy in monitoring the behavior of cells to treatment and thus to evaluate the response to Chemotherapeutic agents and Radiation in Breast Cancer Patients. The results of the study conducted using NFS of Human blood plasma of biopsy proved Breast Cancer patients undergoing treatment are promising, enhancing the scope of Native fluorescence Spectroscopy emerging as a promising technology in the evaluation of Therapeutic Response in Breast Cancer Patients.
[Research on the degradation of BaP with potassium ferrate characterized by fluorescence].

PubMed

Chen, Yu-Zhe; He, Qiang; Yu, Dan-Ni; Li, Si; Tan, Xue-Mei

2012-07-01

The degradation of Benzo(a)pyrene (BaP) by potassium ferrate was researched by means of multiple fluorescence spectroscopic methods such as synchronous, time-scan, excitation emission matrix (EEM) and photometry, under the optimal condition. Within the degradation process, the characteristics of the BaP's concentration at different time-intervals, and the kinetics of the degradation of BaP by potassium ferrate were discussed. From the experimental data, both synchronous and EEM spectra's results showed that the concentration of BaP was reduced 90% by potassium ferrate within 20 s after degradation, and the reaction process was very slow after 60 s. The degradation kinetic equation, ln(F0/Ft) = 0.563 2t + 0.171 2, (R2 = 0.994 2), was obtained through a convenient and fast way combining the time-scan fluorescence data and photometry data, and the photometry included the synchronous photometry and emission photometry. According to the kinetic equation, the degradation of BaP by potassium ferrate was in accord with the order of the first order reaction. So this article could provide a very useful conference for the research on the pollutant degradation by potassium ferrate, especially for the degradation process and the degradation mechanisms.
The identification of hydrophobic sites on the surface of proteins using absorption difference spectroscopy of bromophenol blue.

PubMed

Bertsch, M; Mayburd, A L; Kassner, R J

2003-02-15

Hydrophobic sites on the surface of protein molecules are thought to have important functional roles. The identification of such sites can provide information about the function and mode of interaction with other cellular components. While the fluorescence enhancement of polarity-sensitive dyes has been useful in identifying hydrophobic sites on a number of targets, strong intrinsic quenching of Nile red and ANSA dye fluorescence is observed on binding to a cytochrome c('). Fluorescence quenching is also observed to take place in the presence of a variety of other biologically important molecules which can compromise the quantitative determination of binding constants. Absorption difference spectroscopy is shown not to be sensitive to the presence of fluorescence quenchers but sensitive enough to measure binding constants. The dye BPB is shown to bind to the same hydrophobic sites on proteins as polarity-sensitive fluorescence probes. The absorption spectrum of BPB is also observed to be polarity sensitive. A binding constant of 3x10(6)M(-1) for BPB to BSA has been measured by absorption difference spectroscopy. An empirical correlation is observed between the shape of the absorption difference spectrum of BPB and the polarity of the environment. The results indicate that absorption difference spectroscopy of BPB provides a valuable supplement to fluorescence for determining the presence of hydrophobic sites on the surface of proteins as well as a method for measuring binding constants.
Quantification of zinc-porphyrin in dry-cured ham products by spectroscopic methods Comparison of absorption, fluorescence and X-ray fluorescence spectroscopy.

PubMed

Laursen, Kristoffer; Adamsen, Christina E; Laursen, Jens; Olsen, Karsten; Møller, Jens K S

2008-03-01

Zinc-protoporphyrin (Zn-pp), which has been identified as the major pigment in certain dry-cured meat products, was extracted with acetone/water (75%) and isolated from the following meat products: Parma ham, Iberian ham and dry-cured ham with added nitrite. The quantification of Zn-pp by electron absorption, fluorescence and X-ray fluorescence (XRF) spectroscopy was compared (concentration range used [Zn-pp]=0.8-9.7μM). All three hams were found to contain Zn-pp, and the results show no significant difference among the content of Zn-pp quantified by fluorescence, absorbance and X-ray fluorescence spectroscopy for Parma ham and Iberian ham. All three methods can be used for quantification of Zn-pp in acetone/water extracts of different ham types if the content is higher than 1.0ppm. For dry-cured ham with added nitrite, XRF was not applicable due to the low content of Zn-pp (<0.1ppm). In addition, XRF spectroscopy provides further information regarding other trace elements and can therefore be advantageous in this aspect. This study also focused on XRF determination of Fe in the extracts and as no detectable Fe was found in the three types of ham extracts investigated (limit of detection; Fe⩽1.8ppm), it allows the conclusion that iron containing pigments, e.g., heme, do not contribute to the noticeable red colour observed in some of the extracts.
2D fluorescence spectroscopy for monitoring ion-exchange membrane based technologies - Reverse electrodialysis (RED).

PubMed

Pawlowski, Sylwin; Galinha, Claudia F; Crespo, João G; Velizarov, Svetlozar

2016-01-01

Reverse electrodialysis (RED) is one of the emerging, membrane-based technologies for harvesting salinity gradient energy. In RED process, fouling is an undesirable operation constraint since it leads to a decrease of the obtainable net power density due to increasing stack electric resistance and pressure drop. Therefore, early fouling detection is one of the main challenges for successful RED technology implementation. In the present study, two-dimensional (2D) fluorescence spectroscopy was used, for the first time, as a tool for fouling monitoring in RED. Fluorescence excitation-emission matrices (EEMs) of ion-exchange membrane surfaces and of natural aqueous streams were acquired during one month of a RED stack operation. Fouling evolvement on the ion-exchange membrane surfaces was successfully followed by 2D fluorescence spectroscopy and quantified using principal components analysis (PCA). Additionally, the efficiency of cleaning strategy was assessed by measuring the membrane fluorescence emission intensity before and after cleaning. The anion-exchange membrane (AEM) surface in contact with river water showed to be significantly affected due to fouling by humic compounds, which were found to cross through the membrane from the lower salinity (river water) to higher salinity (sea water) stream. The results obtained show that the combined approach of using 2D fluorescence spectroscopy and PCA has a high potential for studying fouling development and membrane cleaning efficiency in ion exchange membrane processes. Copyright © 2015 Elsevier Ltd. All rights reserved.
Saturation-resolved-fluorescence spectroscopy of Cr3+:mullite glass ceramic

NASA Astrophysics Data System (ADS)

Liu, Huimin; Knutson, Robert; Yen, W. M.

1990-01-01

We present a saturation-based technique designed to isolate and uncouple individual components of inhomogeneously broadened spectra that are simultaneously coupled to each other through spectral overlap and energy-transfer interactions. We have termed the technique saturation-resolved-fluorescence spectroscopy; we demonstrate its usefulness in deconvoluting the complex spectra of Cr3+:mullite glass ceramic.
Emerging applications of fluorescence spectroscopy in medical microbiology field.

PubMed

Shahzad, Aamir; Köhler, Gottfried; Knapp, Martin; Gaubitzer, Erwin; Puchinger, Martin; Edetsberger, Michael

2009-11-26

There are many diagnostic techniques and methods available for diagnosis of medically important microorganisms like bacteria, viruses, fungi and parasites. But, almost all these techniques and methods have some limitations or inconvenience. Most of these techniques are laborious, time consuming and with chances of false positive or false negative results. It warrants the need of a diagnostic technique which can overcome these limitations and problems. At present, there is emerging trend to use Fluorescence spectroscopy as a diagnostic as well as research tool in many fields of medical sciences. Here, we will critically discuss research studies which propose that Fluorescence spectroscopy may be an excellent diagnostic as well as excellent research tool in medical microbiology field with high sensitivity and specificity.
Two-dimensional fluorescence-detected coherent spectroscopy with absolute phasing by confocal imaging of a dynamic grating and 27-step phase-cycling

DOE Office of Scientific and Technical Information (OSTI.GOV)

De, Arijit K., E-mail: akde@lbl.gov; Fleming, Graham R., E-mail: grfleming@lbl.gov; Department of Chemistry, University of California at Berkeley, Berkeley, California 94702

2014-05-21

We present a novel experimental scheme for two-dimensional fluorescence-detected coherent spectroscopy (2D-FDCS) using a non-collinear beam geometry with the aid of “confocal imaging” of dynamic (population) grating and 27-step phase-cycling to extract the signal. This arrangement obviates the need for distinct experimental designs for previously developed transmission detected non-collinear two-dimensional coherent spectroscopy (2D-CS) and collinear 2D-FDCS. We also describe a novel method for absolute phasing of the 2D spectrum. We apply this method to record 2D spectra of a fluorescent dye in solution at room temperature and observe “spectral diffusion.”.
Remote imaging laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy using nanosecond pulses from a mobile lidar system.

PubMed

Grönlund, Rasmus; Lundqvist, Mats; Svanberg, Sune

2006-08-01

A mobile lidar system was used in remote imaging laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) experiments. Also, computer-controlled remote ablation of a chosen area was demonstrated, relevant to cleaning of cultural heritage items. Nanosecond frequency-tripled Nd:YAG laser pulses at 355 nm were employed in experiments with a stand-off distance of 60 meters using pulse energies of up to 170 mJ. By coaxial transmission and common folding of the transmission and reception optical paths using a large computer-controlled mirror, full elemental imaging capability was achieved on composite targets. Different spectral identification algorithms were compared in producing thematic data based on plasma or fluorescence light.
Products from the incomplete metabolism of pyrene by polycyclic aromatic hydrocarbon-degrading bacteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazunga, C.; Aitken, M.D.

Pyrene is a regulated pollutant at sites contaminated with polycyclic aromatic hydrocarbons (PAH). It is mineralized by some bacteria but is also transformed to nonmineral products by a variety of other PAH-degrading bacteria. The authors examined the formation of such products by four bacterial strains and identified and further characterized the most apparently significant of these metabolites. Pseudomonas stutzeri strain P16 and Bacillus cereus strain P21 transformed pyrene primarily to cis-4,5-dihydro-4,5-dihydroxypyrene (PYRdHD), the first intermediate in the known pathway for aerobic bacterial mineralization of pyrene. Sphingomonas yanoikuyae strain R1 transformed pyrene to PYRdHD and pyrene-4,5-dione (PYRQ). Both strain R1 andmore » Pseudomonas saccharophila strain P15 transform PYRdHD to PYRQ nearly stoichiometrically, suggesting that PYRQ is formed by oxidation of PYRdHD to 4,5-dihydroxypyrene and subsequent autoxidation of this metabolite. A pyrene-mineralizing organism, Mycobacterium strain PYR-1, also transforms PYRdHD to PYRQ at high initial concentrations of PYRdHD. However, strain PYR-1 is able to use both PYRdHD and PYRQ as growth substrates. PYRdHD strongly inhibited phenanthrene degradation by strains P15 and R1 but had only a minor effect on strains P16 and P21. At their aqueous saturation concentrations, both PYRdHD and PYRQ severely inhibited benzo[a]pyrene mineralization by strains P15 and R1. Collectively, these findings suggest that products derived from pyrene transformation have the potential to accumulate in PAH-contaminated systems and that such products can significantly influence the removal of other PAH. However, these products may be susceptible to subsequent degradation by organisms able to metabolize pyrene more extensively if such organisms are present in the system.« less
Quantitative structural modeling on the wavelength interval (Δλ) in synchronous fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Samari, Fayezeh; Yousefinejad, Saeed

2017-11-01

Emission fluorescence spectroscopy has an extremely restricted scope of application to analyze of complex mixtures since its selectivity is reduced by the extensive spectral overlap. Synchronous fluorescence spectroscopy (SFS) is a technique enables us to analyze complex mixtures with overlapped emission and/or excitation spectra. The difference of excitation and emission wavelength of compounds (interval wavelength or Δλ) is an important characteristic in SFS. Thus a multi-parameter model was constructed to predict Δλ in 63 fluorescent compounds and the regression coefficient in training set, cross validation and test set were 0.88, 0.85 and 0.91 respectively. Furthermore, the applicability and validity of model were evaluated using different statistical methods such as y-scrambling and applicability domain. It was concluded that increasing average valence connectivity, number of Al2-NH functional group and Geary autocorrelation (lag 4) with electronegative weights can lead to increasing Δλ in the fluorescent compounds. The current study obtained an insight into the structural properties of compounds effective on their Δλ as an important parameter in SFS.
Nonnegative constraint analysis of key fluorophores within human breast cancer using native fluorescence spectroscopy excited by selective wavelength of 300 nm

NASA Astrophysics Data System (ADS)

Pu, Yang; Sordillo, Laura A.; Alfano, Robert R.

2015-03-01

Native fluorescence spectroscopy offers an important role in cancer discrimination. It is widely acknowledged that the emission spectrum of tissue is a superposition of spectra of various salient fluorophores. In this study, the native fluorescence spectra of human cancerous and normal breast tissues excited by selected wavelength of 300 nm are used to investigate the key building block fluorophores: tryptophan and reduced nicotinamide adenine dinucleotide (NADH). The basis spectra of these key fluorophores' contribution to the tissue emission spectra are obtained by nonnegative constraint analysis. The emission spectra of human cancerous and normal tissue samples are projected onto the fluorophore spectral subspace. Since previous studies indicate that tryptophan and NADH are key fluorophores related with tumor evolution, it is essential to obtain their information from tissue fluorescence but discard the redundancy. To evaluate the efficacy of for cancer detection, linear discriminant analysis (LDA) classifier is used to evaluate the sensitivity, and specificity. This research demonstrates that the native fluorescence spectroscopy measurements are effective to detect changes of fluorophores' compositions in tissues due to the development of cancer.
Stable environmentally sensitive cationic hydrogels for controlled delivery applications.

PubMed

Deo, Namita; Ruetsch, S; Ramaprasad, K R; Kamath, Y

2010-01-01

New thermosensitive, cationic hydrogels were synthesized by the dispersion copolymerization of N-isopropylacrylamide (NIPAM) and (3-acrylamidopropyl)trimethylammonium chloride (AAPTAC). In the polymerization protocol, an amide-based comonomer, (3-acrylamidopropyl)trimethylammonium chloride, was reacted as a new alternative monomer for introducing positive charges into the thermosensitive hydrogel. The hydrogels were synthesized without making any pH adjustment in the aqueous medium. These hydrogel particles exhibited colloidal stability in the pH range of 1.5 to 11.0, while similar cationic hydrogels were reported to be unstable at pHs higher than 6. The stronger cationic character of the selected comonomer provided higher colloidal stability to the poly(NIPAM-co-AAPTAC) hydrogels. Furthermore, these hydrogels displayed sensitivity towards temperature, pH, and salt concentration. Interestingly, the particle size of hydrogels was found to be decreased significantly with an increase in temperature and salt concentration. In addition, using pyrene fluorescence spectroscopy, it was established that the hydrophobicity/hydrophilicity of the hydrogel particles was largely controlled by both pH and temperature. The thermosensitive hydrogels reported in this paper may be suitable for delivering different actives for cosmetic and medical applications. Although direct application of these hydrogel particles in cosmetics has not been shown at this stage, the methodology of making them and controlling their absorption and release properties as a function of temperature and pH has been demonstrated. Furthermore, these hydrogels may also have applications in scavenging organic and inorganic toxics.
The effect of caffeine on the reactions of the excited singlet state of pyrene in micellar sodium lauryl sulfate

NASA Astrophysics Data System (ADS)

Hashimoto, Shuichi; Thomas, J. Kerry

1984-08-01

The effect of caffeine on a few photo-induced reactions of pyrene in micellar sodium lauryl sulfate (NaLS) has been studied. In these systems caffeine complexes with the pyrene (K asso = 85 ± 10 M -1 and also with the other reactants, e.g. Cu 2+ or TI +. The efficiencies of reactions which involve contact, i.e. pyrene excimer formation, and quenching by TI + ions to give the triplet state of pyrene, are significantly reduced in the presence of caffeine, due to geometric inhibitions formed by the complexation processes. The kinetics of photo-induced electron transfer, e.g. between excited pyrene and Cu 2+, are not affected. However, the subsequent reactions of the products are modified and the yield of ionic products is markedly increased.
Interplay of localized pyrene chromophores and π-conjugation in novel poly(2,7-pyrene) ladder polymers

NASA Astrophysics Data System (ADS)

Rudnick, Alexander; Kass, Kim-Julia; Preis, Eduard; Scherf, Ullrich; Bässler, Heinz; Köhler, Anna

2017-05-01

We present a detailed spectroscopic study, along with the synthesis, of conjugated, ladder-type 2,7-linked poly(pyrene)s. We observe a delocalization of the first singlet excited state along the polymer backbone, i.e., across the 2,7 linkage in the pyrene moiety, in contrast to earlier studies on conjugated 2,7-linked poly(pyrene)s without ladder structure. The electronic signature of the pyrene unit is, however, manifested in an increased lifetime and reduced oscillator strength as well as a modified vibronic progression in absorption of the singlet state compared to a ladder-type poly(para-phenylene) (MeLPPP). Furthermore, the reduced oscillator strength and increased lifetime slow down Förster-type energy transfer in films, where this transfer occurs to sites with increasing inter-chain coupling of H-type nature.
Life history traits and the activity of antioxidative enzymes in Lymantria dispar L. (lepidoptera, lymantriidae) larvae exposed to benzo[a]pyrene.

PubMed

Ilijin, Larisa; Mrdaković, Marija; Todorović, Dajana; Vlahović, Milena; Gavrilović, Anja; Mrkonja, Aleksandra; Perić-Mataruga, Vesna

2015-11-01

Increased presence of benzo[a]pyrene in the environment underlines the need for development of sensitive biomarkers for monitoring. Antioxidative enzymes could be used as early-warning signals because of their sensitivity and applicability. The activity of 2 antioxidative enzymes, superoxide dismutase (SOD) and catalase (CAT), were measured in midgut tissues of fifth instar Lymantria dispar larvae exposed to different concentrations of benzo[a]pyrene: 2 ng, 10 ng, 20 ng, 100 ng, 200 ng, and 2000 ng benzo[a]pyrene/g dry food weight. Larval development, larval mass, and relative growth rate were also monitored. The authors detected prolonged larval development, as well as reduced larval mass and relative growth rate in larvae exposed to all benzo[a]pyrene concentrations. The L. dispar midgut SOD activity was significantly increased, and 2 SOD isoforms were detected on native polyacrylamide gel electrophoresis in larvae fed on artificial diet supplemented with benzo[a]pyrene. In contrast, the control group had only 1 isoform. Catalase activity was significantly increased in all benzo[a]pyrene-treated larvae. Native gel electrophoresis showed that a switch in active CAT isoforms occurred after benzo[a]pyrene treatment. Thus, SOD and CAT in polyphagous herbivorous L. dispar larvae are very sensitive to low concentrations of benzo[a]pyrene. Therefore, they could be used as biomarkers for exposure and effects of this toxic polycyclic aromatic hydrocarbon. © 2015 SETAC.
Topological, functional, and dynamic properties of the protein interaction networks rewired by benzo(a)pyrene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ba, Qian; Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing; Li, Junyang

2015-03-01

Benzo(a)pyrene is a common environmental and foodborne pollutant that has been identified as a human carcinogen. Although the carcinogenicity of benzo(a)pyrene has been extensively reported, its precise molecular mechanisms and the influence on system-level protein networks are not well understood. To investigate the system-level influence of benzo(a)pyrene on protein interactions and regulatory networks, a benzo(a)pyrene-rewired protein interaction network was constructed based on 769 key proteins derived from more than 500 literature reports. The protein interaction network rewired by benzo(a)pyrene was a scale-free, highly-connected biological system. Ten modules were identified, and 25 signaling pathways were enriched, most of which belong tomore » the human diseases category, especially cancer and infectious disease. In addition, two lung-specific and two liver-specific pathways were identified. Three pathways were specific in short and medium-term networks (< 48 h), and five pathways were enriched only in the medium-term network (6 h–48 h). Finally, the expression of linker genes in the network was validated by Western blotting. These findings establish the overall, tissue- and time-specific benzo(a)pyrene-rewired protein interaction networks and provide insights into the biological effects and molecular mechanisms of action of benzo(a)pyrene. - Highlights: • Benzo(a)pyrene induced scale-free, highly-connected protein interaction networks. • 25 signaling pathways were enriched through modular analysis. • Tissue- and time-specific pathways were identified.« less
ASSOCIATION BETWEEN MUTATION SPECTRUM AND PERSISTENT DNA ADDUCT PROFILE IN SALMONELLA FOR BENZO[A]PYRENE AND DIBENZO[A]PYRENE

EPA Science Inventory

Dibenzo[a,l]pyrene (DB[a1]P) is less prevalent in the environment but 100-200X more carcinogenic in rodents than benzo[a]pyrene (B[a]P) .B[a]P induces most of its adducts on G, whereas DB[a,1]P produces most its adducts on A. Using the Salmonella mutagenicity assay, we have exami...
MUTATIONS INDUCED BY BENZO[ A ]PYRENE AND DIBENZO[ A,L ]PYRENE IN LACI TRANSGENIC B6C3F1 MOUSE LUNG RESULT FROM STABLE DNA ADDUCTS

EPA Science Inventory

Dibenzo[a,l]pyrene (DB[a,l]P) and benzo[a]pyrene (B[a]P) are carcinogenic polycyclic aromatic hydrocarbons (PAH) that are each capable of forming a variety of covalent adducts with DNA, some of which spontaneously depurinate, producing apurinic (AP) si...

Mutations Induced by Benzo[a]pyrene and Dibenzo[a,l]pyrene in lacI Transgenic B6C3F1 Mouse Lung Result from Stable DNA Adducts

EPA Science Inventory

Dibenzo[a,l]pyrene (DB[a,l]P) and benzo[a]pyrene (B[a]P) are carcinogenic polycyclic aromatic hydrocarbons (PAH) that are each capable of forming a variety of covalent adducts with DNA. Some of the DNA adducts formed by these PAHs have been demonstrated to spontaneously depurina...
Polycyclic aromatic hydrocarbons degradation by marine-derived basidiomycetes: optimization of the degradation process.

PubMed

Vieira, Gabriela A L; Magrini, Mariana Juventina; Bonugli-Santos, Rafaella C; Rodrigues, Marili V N; Sette, Lara D

2018-05-03

Pyrene and benzo[a]pyrene (BaP) are high molecular weight polycyclic aromatic hydrocarbons (PAHs) recalcitrant to microbial attack. Although studies related to the microbial degradation of PAHs have been carried out in the last decades, little is known about degradation of these environmental pollutants by fungi from marine origin. Therefore, this study aimed to select one PAHs degrader among three marine-derived basidiomycete fungi and to study its pyrene detoxification/degradation. Marasmiellus sp. CBMAI 1062 showed higher levels of pyrene and BaP degradation and was subjected to studies related to pyrene degradation optimization using experimental design, acute toxicity, organic carbon removal (TOC), and metabolite evaluation. The experimental design resulted in an efficient pyrene degradation, reducing the experiment time while the PAH concentration applied in the assays was increased. The selected fungus was able to degrade almost 100% of pyrene (0.08mgmL -1 ) after 48h of incubation under saline condition, without generating toxic compounds and with a TOC reduction of 17%. Intermediate metabolites of pyrene degradation were identified, suggesting that the fungus degraded the compound via the cytochrome P450 system and epoxide hydrolases. These results highlight the relevance of marine-derived fungi in the field of PAH bioremediation, adding value to the blue biotechnology. Copyright © 2018. Published by Elsevier Editora Ltda.
Community structure and PAH ring-hydroxylating dioxygenase genes of a marine pyrene-degrading microbial consortium.

PubMed

Gallego, Sara; Vila, Joaquim; Tauler, Margalida; Nieto, José María; Breugelmans, Philip; Springael, Dirk; Grifoll, Magdalena

2014-07-01

Marine microbial consortium UBF, enriched from a beach polluted by the Prestige oil spill and highly efficient in degrading this heavy fuel, was subcultured in pyrene minimal medium. The pyrene-degrading subpopulation (UBF-Py) mineralized 31 % of pyrene without accumulation of partially oxidized intermediates indicating the cooperation of different microbial components in substrate mineralization. The microbial community composition was characterized by culture dependent and PCR based methods (PCR-DGGE and clone libraries). Molecular analyses showed a highly stable community composed by Alphaproteobacteria (84 %, Breoghania, Thalassospira, Paracoccus, and Martelella) and Actinobacteria (16 %, Gordonia). The members of Thalasosspira and Gordonia were not recovered as pure cultures, but five additional strains, not detected in the molecular analysis, that classified within the genera Novosphingobium, Sphingopyxis, Aurantimonas (Alphaproteobacteria), Alcanivorax (Gammaproteobacteria) and Micrococcus (Actinobacteria), were isolated. None of the isolates degraded pyrene or other PAHs in pure culture. PCR amplification of Gram-positive and Gram-negative dioxygenase genes did not produce results with any of the cultured strains. However, sequences related to the NidA3 pyrene dioxygenase present in mycobacterial strains were detected in UBF-Py consortium, suggesting the representative of Gordonia as the key pyrene degrader, which is consistent with a preeminent role of actinobacteria in pyrene removal in coastal environments affected by marine oil spills.
Inoculating wheat (Triticum aestivum L.) with the endophytic bacterium Serratia sp. PW7 to reduce pyrene contamination.

PubMed

Zhu, Xuezhu; Wang, Wanqing; Sun, Kai; Lin, Xianghao; Li, Shuang; Waigi, Michael Gatheru; Ling, Wanting

2017-08-03

This research was conducted to find an optimal inoculation way for a pyrene-degrading endophytic Serratia sp. PW7 to colonize wheat for reducing pyrene contamination. Three inoculation ways, which are soaking seeds in inocula (TS), dipping roots of seedlings in inocula (TR), and spraying inocula on leaves of seedlings (TL), were used in this study. Inoculated seedlings and noninoculated seedlings (CK) were, respectively, cultivated in Hoagland solutions supplemented with pyrene in a growth chamber. The results showed that strain PW7 successfully colonized the inoculated seedlings in high numbers, and significantly promoted the growth of seedlings (TS and TR). More importantly, strain PW7 reduced pyrene levels in the seedlings and the Hoagland solutions. Compared to the noninoculated seedlings, the pyrene contents of the inoculated seedlings were decreased by 35.7-86.3% in the shoots and by 26.8-60.1% in the roots after 8-day cultivation. By comparing the efficiencies of decreasing pyrene residues, it can be concluded that TR was an optimal inoculation way for endophytic strains to colonize the inoculated plants and to reduce the pyrene contamination. Our findings provide an optimized inoculation way to reduce organic contamination in crops by inoculating plants with functional endophytic bacteria.
Toxicological effects of benzo[a]pyrene on DNA methylation of whole genome in ICR mice.

PubMed

Zhao, L; Zhang, S; An, X; Tan, W; Pang, D; Ouyang, H

2015-10-30

It has been well known that alterations in DNA methylation - an important regulator of gene transcription - lead to cancer. Therefore a change in the level of DNA methylation of whole genome has been considered as a biomarker of carcinogenesis. Previously, a large number of experimental results in genetic toxicology have showed that benzo[a]pyrene could cause DNA mutation and fragmentation. However, there was little to no studies on alterations in DNA methylation of genome directly result from exposure to benzo[a]pyrene. In this paper, possible mechanisms of alterations in whole genomic DNA methylation by benzo[a]pyrene were investigated using ICR mice after benzo[a]pyrene exposure. The blood, liver, pancreas, skin, lung and bladder of ICR mice were removed and checked after a fixed time interval (6 hours) of benzo[a]pyrene exposure, and whole genomic DNA methylation level was determined by high performance liquid chromatography (HPLC). The results exhibited tissue specificity, that is, the level of whole genomic DNA methylation decreases significantly in blood and liver, rather than pancreas, lung, skin and bladder of ICR mice. This study investigated the direct relationship between aberrant DNA methylation level and benzo[a]pyrene exposure, which might be helpful to clarify the toxicological mechanism of benzo[a]pyrene in epigenetic perspectives.
The use of one- and two- photon induced fluorescence spectroscopy for the optical characterization of carcinogenic aflatoxins

NASA Astrophysics Data System (ADS)

Smeesters, L.; Meulebroeck, W.; Raeymaekers, S.; Thienpont, H.

2014-09-01

Carcinogenic and toxic contaminants in food and feed products are nowadays mostly detected by destructive, time-consuming chemical analyses, like HPLC and LC-MS/MS methods. However, as a consequence of the severe and growing regulations on food products by the European Union, there arose an increased demand for the ultra-fast, high-sensitive and non-destructive detection of contaminants in food and feed products. Therefore, we have investigated fluorescence spectroscopy for the characterization of carcinogenic aflatoxins. With the use of a tunable titanium-sapphire laser in combination with second and third harmonic wavelength generation, both one- and two-photon induced fluorescence excitation wavelengths could be generated using the same setup. We characterized and compared the one- and two-photon induced fluorescence spectra of pure aflatoxin powder, after excitation with 365nm and 730nm respectively. Moreover, we investigated the absolute fluorescence intensity as function of the excitation power density. Afterwards, we applied our characterization setup to the detection of aflatoxins in maize grains. The fluorescence spectra of both healthy and contaminated maize samples were experimentally characterized. In addition to the fluorescence spectrum of the pure aflatoxin, we observed an unwanted influence of the intrinsic fluorescence of the maize. Depending on the excitation wavelength, a varying contrast between the fluorescence spectra of the healthy and contaminated samples was obtained. After a comparison of the measured fluorescence signals, a detection criterion for the optical identification of the contaminated maize samples could be defined. As a result, this illustrates the use of fluorescence spectroscopy as a valuable tool for the non-destructive, real-time and high-sensitive detection of aflatoxins in maize.
IRIS Toxicological Review of Benzo[a]pyrene (Final Report) ...

EPA Pesticide Factsheets

EPA has finalized the Integrated Risk Information System (IRIS) assessment of benzo[a]pyrene. This assessment addresses the potential cancer and noncancer human health effects from long-term exposure to benzo[a]pyrene. Now final, this assessment will update the toxicological information on benzo[a]pyrene posted in 1987. EPA’s program and regional offices may use this assessment to inform decisions to protect human health. EPA is undertaking an update of the Integrated Risk Information System (IRIS) health assessment for benzo[a]pyrene (BaP). The outcome of this project is an updated Toxicological Review and IRIS Summary for BaP that will be entered into the IRIS database.
Interactive effects of PAHs with different rings and As on their uptake, transportation, and localization in As hyperaccumulator.

PubMed

Liao, Xiaoyong; Wu, Zeying; Ma, Xu; Gong, Xuegang; Yan, Xiulan

2017-11-01

In order to illuminate the mechanism of the interaction of polycyclic aromatic hydrocarbon (PAH) with different benzene rings and arsenic (As) in As hyperaccumulator, Pteris vittata L., the uptakes of PAHs were investigated using hydroponics simulation and localizations of PAHs in the plant were determined using two-photon laser scanning confocal microscopy (TPLSCM). The results showed that the total As concentration in different parts of P. vittata decreased in the presence of PAHs with increased numbers of benzene rings: 38.0-47.4% for benzo(a)pyrene (BaP, five rings), 20.5-35.9% for pyrene (PYR, four rings), and 13.7-16.6% for fluorine (FLU, three rings). BaP and PYR concentrations increased, while FLU concentration decreased in the presence of As. The results of TPLSCM revealed that PAHs distributed in epidermal cells of roots, xylem, and endothelial cells of rachis, epidermis, and stomatal cells of pinnae; however, the fluorescence intensity of BaP and PYR were higher than FLU significantly in plant. This study provided important basis to further research on interactive effects of PAHs and As in the P. vittata. These findings were important to understand the mechanisms of PAH and As translocation and distribution by P. vittata.
Development of Methods for the Real-Time and Rapid Identification and Detection of TSE in Living Animals Using Fluorescence Spectroscopy of the Eye

DTIC Science & Technology

2005-07-01

and cow eyes and performed fluorescence spectroscopy on all the major eye components and reports that the cornea, lens, retina , and optic nerve show...appears that while the optic nerve presents the richest spectra with the most detail, the retina is the most promising target for use as a probe. This... retinas is striking and is illustrated in Figure 1. • Preliminary data of total eye fluorescence from mice as a function of age are presented
Excitation Anisotropy in Laser-Induced-Fluorescence Spectroscopy —High-Intensity, Broad-Line Excitation

NASA Astrophysics Data System (ADS)

Hirabayashi, Atsumu; Nambu, Yoshihiro; Fujimoto, Takashi

1986-10-01

The problem of excitation anisotropy in laser-induced-fluorescence spectroscopy (LIFS) was investigated for the intense excitation case under the broad-line condition. The depolarization coefficient for the fluorescence light was derived in the intense-excitation limit (linearly-polarized or unpolarized light excitation) and the results are presented in tables. In the region of intermediate intensity, between the weak and intense-excitation limits, the master equation was solved for a specific example of atomic transitions and its result is compared with experimental results.
Emerging biomedical applications of time-resolved fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Lakowicz, Joseph R.; Szmacinski, Henryk; Koen, Peter A.

1994-07-01

Time-resolved fluorescence spectroscopy is presently regarded as a research tool in biochemistry, biophysics, and chemical physics. Advances in laser technology, the development of long-wavelength probes, and the use of lifetime-based methods are resulting in the rapid migration of time-resolved fluorescence to the clinical chemistry lab, to the patient's bedside, to flow cytometers, to the doctor's office, and even to home health care. Additionally, time-resolved imaging is now a reality in fluorescence microscopy, and will provide chemical imaging of a variety of intracellular analytes and/or cellular phenomena. In this overview paper we attempt to describe some of the opportunities available using chemical sensing based on fluorescence lifetimes, and to predict those applications of lifetime-based sensing which are most likely in the near future.
Synthesis, characterization and air stable semiconductor properties of thiophene-condensed pyrene derivatives

NASA Astrophysics Data System (ADS)

Moriguchi, Tetsuji; Higashi, Makoto; Yakeya, Daisuke; Jalli, Venkataprasad; Tsuge, Akihiko; Okauchi, Tatsuo; Nagamatsu, Shuichi; Takashima, Wataru

2017-01-01

New and simple polyaromatic compounds containing two thiophene rings were prepared via photo-cyclization and their structural and photophysical properties were evaluated via 1H NMR spectroscopy and X-ray crystallographic analysis. On the basis of X-ray analysis, it was determined that the molecular structure of the compound was highly strained and that they contain two hetero [4] helicene moieties. The compounds were investigated as active layer in p-type organic field-effect transistors (p-OFET) in top contact type devices. Notably, the compound containing two thiophene components exhibited very stable p-type semiconducting behavior in moist air.
Application of normal fluorescence and stability-indicating derivative synchronous fluorescence spectroscopy for the determination of gliquidone in presence of its fluorescent alkaline degradation product

NASA Astrophysics Data System (ADS)

El-ghobashy, Mohamed R.; Yehia, Ali M.; Helmy, Aya H.; Youssef, Nadia F.

2018-01-01

Simple, smart and sensitive normal fluorescence and stability-indicating derivative synchronous spectrofluorimetric methods have been developed and validated for the determination of gliquidone in the drug substance and drug product. Normal spectrofluorimetric method of gliquidone was established in methanol at λ excitation 225 nm and λ emission 400 nm in concentration range 0.2-3 μg/ml with LOD equal 0.028. The fluorescence quantum yield of gliquidone was calculated using quinine sulfate as a reference and found to be 0.542. Stability-indicating first and third derivative synchronous fluorescence spectroscopy were successfully utilized to overcome the overlapped spectra in normal fluorescence of gliquidone and its alkaline degradation product. Derivative synchronous methods are based on using the synchronous fluorescence of gliquidone and its degradation product in methanol at Δ λ50 nm. Peak amplitude in the first derivative of synchronous fluorescence spectra was measured at 309 nm where degradation product showed zero-crossing without interference. The peak amplitudes in the third derivative of synchronous fluorescence spectra, peak to trough were measured at 316,329 nm where degradation product showed zero-crossing. The different experimental parameters affecting the normal and synchronous fluorescence intensity of gliquidone were studied and optimized. Moreover, the cited methods have been validated as per ICH guidelines. The peak amplitude-concentration plots of the derivative synchronous fluorescence were linear over the concentration range 0.05-2 μg/ml for gliquidone. Limits of detection were 0.020 and 0.022 in first and third derivative synchronous spectra, respectively. The adopted methods were successfully applied to commercial tablets and the results demonstrated that the derivative synchronous fluorescence spectroscopy is a powerful stability-indicating method, suitable for routine use with a short analysis time. Statistical comparison between the results obtained by normal fluorescence and derivative synchronous methods and the official one using student's t-test and F-ratio showed no significant difference regarding accuracy and precision.
Hyperspectral Imaging and Spectroscopy of Fluorescently Coupled Acyl-CoA: Cholesterol Acyltransferase in Insect Cells

NASA Technical Reports Server (NTRS)

Malak, H.; Mahtani, H.; Herman, P.; Vecer, J.; Lu, X.; Chang, T. Y.; Richmond, Robert C.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

A high-performance hyperspectral imaging module with high throughput of light suitable for low-intensity fluorescence microscopic imaging and subsequent analysis, including single-pixel-defined emission spectroscopy, was tested on Sf21 insect cells expressing green fluorescence associated with recombinant green fluorescent protein linked or not with the membrane protein acyl-CoA:cholesterol acyltransferase. The imager utilized the phenomenon of optical activity as a new technique providing information over a spectral range of 220-1400 nm, and was inserted between the microscope and an 8-bit CCD video-rate camera. The resulting fluorescence image did not introduce observable image aberrations. The images provided parallel acquisition of well resolved concurrent spatial and spectral information such that fluorescence associated with green fluorescent protein alone was demonstrated to be diffuse within the Sf21 insect cell, and that green fluorescence associated with the membrane protein was shown to be specifically concentrated within regions of the cell cytoplasm. Emission spectra analyzed from different regions of the fluorescence image showed blue shift specific for the regions of concentration associated with the membrane protein.
Fluorescence Spectroscopy as a Tool for the Assessment of Liver Samples with Several Stages of Fibrosis.

PubMed

Fabila-Bustos, Diego A; Arroyo-Camarena, Úrsula D; López-Vancell, María D; Durán-Padilla, Marco A; Azuceno-García, Itzel; Stolik-Isakina, Suren; Valor-Reed, Alma; Ibarra-Coronado, Elizabeth; Hernández-Quintanar, Luis F; Escobedo, Galileo; de la Rosa-Vázquez, José M

2018-03-01

During the last years, fluorescence spectroscopy has been used as a potential tool for the evaluation and characterization of tissues with different disease conditions due to its low cost, high sensitivity, and minimally or noninvasive character. In this study, fluorescence spectroscopy was used to study 19 paraffin blocks containing human liver tissue from biopsies. All samples were previously analyzed by two senior pathologists in a single-blind trial. After their evaluation, four liver samples were classified as nonfibrosis (F0), four as initial fibrosis (F1-F2), four as advanced fibrosis (F3), and six as cirrhosis (F4). The fluorescence was induced at different wavelengths as follows: 330, 365, and 405 nm using a portable fiber-optic system. The fluorescence spectra were recorded in the range of 400-750 nm. A distinctive correlation between the shape of each spectrum and the level of fibrosis in the liver sample was detected. A multi-variate statistical analysis based on principal component analysis followed by linear discrimination analysis was applied to develop algorithms able to distinguish different stages of fibrosis based on the characteristics of fluorescence spectra. Pairwise comparisons were performed: F0 versus F1-F2, F1-F2 versus F3, F3 versus F4, and F1-F2 versus F4. The algorithms applied to each set of data yielded values of sensitivity and specificity that were higher than 90% and 95%, respectively, in all the analyzed cases. With this study, it is concluded that fluorescence spectroscopy can be used as a complementary tool for the assessment of liver fibrosis in liver tissue samples, which sets the stage for subsequent clinical trials.
Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, Matthew W.

2013-01-01

This thesis outlines advancements in Raman scatter enhancement techniques by applying evanescent fields, standing-waves (waveguides) and surface enhancements to increase the generated mean square electric field, which is directly related to the intensity of Raman scattering. These techniques are accomplished by employing scanning angle Raman spectroscopy and surface enhanced Raman spectroscopy. A 1064 nm multichannel Raman spectrometer is discussed for chemical analysis of lignin. Extending dispersive multichannel Raman spectroscopy to 1064 nm reduces the fluorescence interference that can mask the weaker Raman scattering. Overall, these techniques help address the major obstacles in Raman spectroscopy for chemical analysis, which include themore » inherently weak Raman cross section and susceptibility to fluorescence interference.« less
Very High Spectral Resolution Imaging Spectroscopy: the Fluorescence Explorer (FLEX) Mission

NASA Technical Reports Server (NTRS)

Moreno, Jose F.; Goulas, Yves; Huth, Andreas; Middleton, Elizabeth; Miglietta, Franco; Mohammed, Gina; Nedbal, Ladislav; Rascher, Uwe; Verhoef, Wouter; Drusch, Matthias

2016-01-01

The Fluorescence Explorer (FLEX) mission has been recently selected as the 8th Earth Explorer by the European Space Agency (ESA). It will be the first mission specifically designed to measure from space vegetation fluorescence emission, by making use of very high spectral resolution imaging spectroscopy techniques. Vegetation fluorescence is the best proxy to actual vegetation photosynthesis which can be measurable from space, allowing an improved quantification of vegetation carbon assimilation and vegetation stress conditions, thus having key relevance for global mapping of ecosystems dynamics and aspects related with agricultural production and food security. The FLEX mission carries the FLORIS spectrometer, with a spectral resolution in the range of 0.3 nm, and is designed to fly in tandem with Copernicus Sentinel-3, in order to provide all the necessary spectral / angular information to disentangle emitted fluorescence from reflected radiance, and to allow proper interpretation of the observed fluorescence spatial and temporal dynamics.
Improvement of reverse-phase high pressure liquid chromatographic resolution of benzo(a)pyrene metabolites using organic amines: application to metabolites produced by fish

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tjessum, K.; Stegeman, J.J.

1979-10-15

Addition of primary organic amines, such as n-butylamine, to the mobile phase altered the capacity factors and selectivity of benzo(a)pyrene metabolites obtained with reverse-phase high pressure liquid chromatography on an ODS column. Separation of benzo(a)pyrene phenols in particular was improved with 8 of the 10 available metabolites resolved, including those known to be biologically produced. The method offers sufficiently improved resolution or convenience that it should prove useful in comparative studies of metabolism of benzo(a)-pyrene and other polynuclear aromatic hydrocarbons. Applying the method to analysis of benzo(a)pyrene metabolites produced in vitro by hepatic microsomes from the marine fish Stenotomus versicolormore » indicated the principal phenolic derivatives produced by this fish were 1-hydroxy-, 3-hydroxy-, 7-hydroxy-, and 9-hydroxybenzo(a)pyrene.« less
Exposure Assessment of Polycyclic Aromatic Hydrocarbon (PAHs) in Childcare Centers of Muang, Nakhon Ratchasima

NASA Astrophysics Data System (ADS)

Jitlada, C.; Pentamwa, P.

2018-03-01

This study aims to characterize airborne polycyclic aromatic hydrocarbons (PAHs) as of particulate and vapor phases variation. The samples were collected from the childcare centers where divided into urban and rural areas in Nakhon Ratchasima Province of Thailand. The airborne samples were collected from five childcare centers during the dry season in the year 2017. The PAHs species were determined by the gas chromatography and mass spectroscopy (GS/MS) method. Results show that the total concentrations of PAHs were higher than vapor phase that both similar in urban area and rural area. The dominant PAHs compounds of both urban and rural areas were benzo(a)pyrene, benzo(a,h)anthracene and indeno(1,2,3-cd)pyrene, respectively. Furthermore, the concentrations of PAHs in municipality (urban) childcare centers were higher than rural childcare centers area of Nakhon Ratchasima province. The risks associated with exposure to PAHs were evaluated using the TEF approach. The estimated value of lifetime lung cancer risks children in urban were significantly (p < 0.05) 2 times of children in rural, thus demonstrating that exposure to PAHs at levels found at urban site may be cause potential health risks.
A Project-Based Biochemistry Laboratory Promoting the Understanding and Uses of Fluorescence Spectroscopy in the Study of Biomolecular Structures and Interactions

ERIC Educational Resources Information Center

Briese, Nicholas; Jakubowsk, Henry V.

2007-01-01

A laboratory project for a first semester biochemistry course is described, which integrates the traditional classroom study of the structure and function of biomolecules with the laboratory study of these molecules using fluorescence spectroscopy. Students are assigned a specific question addressing the stability/function of lipids, proteins, or…

Fluorescence Spectroscopy of tRNA[superscript Phe] Y Base in the Presence of Mg[superscript 2+] and Small Molecule Ligands

ERIC Educational Resources Information Center

Kirk, Sarah R.; Silverstein, Todd P.; McFarlane Holman, Karen L.

2008-01-01

This laboratory project is one component of a semester-long advanced biochemistry laboratory course that uses several complementary techniques to study tRNA[superscript Phe] conformational changes induced by ligand binding. In this article we describe a set of experiments in which students use fluorescence spectroscopy to study tRNA[superscript…
An Assessment of macro-scale in situ Raman and ultraviolet-induced fluorescence spectroscopy for rapid characterization of frozen peat and ground ice

NASA Astrophysics Data System (ADS)

Laing, Janelle R.; Robichaud, Hailey C.; Cloutis, Edward A.

2016-04-01

The search for life on other planets is an active area of research. Many of the likeliest planetary bodies, such as Europa, Enceladus, and Mars are characterized by cold surface environments and ice-rich terrains. Both Raman and ultraviolet-induced fluorescence (UIF) spectroscopies have been proposed as promising tools for the detection of various kinds of bioindicators in these environments. We examined whether macro-scale Raman and UIF spectroscopy could be applied to the analysis of unprocessed terrestrial frozen peat and clear ground ice samples for detection of bioindicators. It was found that this approach did not provide unambiguous detection of bioindicators, likely for a number of reasons, particularly due to strong broadband induced fluorescence. Other contributing factors may include degradation of organic matter in frozen peat to the point that compound-specific emitted fluorescence or Raman peaks were not resolvable. Our study does not downgrade the utility of either UIF or Raman spectroscopy for astrobiological investigations (which has been demonstrated in previous studies), but does suggest that the choice of instrumentation, operational conditions and sample preparation are important factors in ensuring the success of these techniques.
Sexing of chicken eggs by fluorescence and Raman spectroscopy through the shell membrane

PubMed Central

Preusse, Grit; Schnabel, Christian; Bartels, Thomas; Cramer, Kerstin; Krautwald-Junghanns, Maria-Elisabeth; Koch, Edmund; Steiner, Gerald

2018-01-01

In order to provide an alternative to day-old chick culling in the layer hatcheries, a noninvasive method for egg sexing is required at an early stage of incubation before onset of embryo sensitivity. Fluorescence and Raman spectroscopy of blood offers the potential for precise and contactless in ovo sex determination of the domestic chicken (Gallus gallus f. dom.) eggs already during the fourth incubation day. However, such kind of optical spectroscopy requires a window in the egg shell, is thus invasive to the embryo and leads to decreased hatching rates. Here, we show that near infrared Raman and fluorescence spectroscopy can be performed on perfused extraembryonic vessels while leaving the inner egg shell membrane intact. Sparing the shell membrane makes the measurement minimally invasive, so that the sexing procedure does not affect hatching rates. We analyze the effect of the membrane above the vessels on fluorescence signal intensity and on Raman spectrum of blood, and propose a correction method to compensate for it. After compensation, we attain a correct sexing rate above 90% by applying supervised classification of spectra. Therefore, this approach offers the best premises towards practical deployment in the hatcheries. PMID:29474445
Room temperature spectrally resolved single-molecule spectroscopy reveals new spectral forms and photophysical versatility of aequorea green fluorescent protein variants.

PubMed

Blum, Christian; Meixner, Alfred J; Subramaniam, Vinod

2004-12-01

It is known from ensemble spectroscopy at cryogenic temperatures that variants of the Aequorea green fluorescent protein (GFP) occur in interconvertible spectroscopically distinct forms which are obscured in ensemble room temperature spectroscopy. By analyzing the fluorescence of the GFP variants EYFP and EGFP by spectrally resolved single-molecule spectroscopy we were able to observe spectroscopically different forms of the proteins and to dynamically monitor transitions between these forms at room temperature. In addition to the predominant EYFP B-form we have observed the blue-shifted I-form thus far only seen at cryogenic temperatures and have followed transitions between these forms. Further we have identified for EYFP and for EGFP three more, so far unknown, forms with red-shifted fluorescence. Transitions between the predominant forms and the red-shifted forms show a dark time which indicates the existence of a nonfluorescent intermediate. The spectral position of the newly-identified red-shifted forms and their formation via a nonfluorescent intermediate hint that these states may account for the possible photoactivation observed in bulk experiments. The comparison of the single-protein spectra of the red-shifted EYFP and EGFP forms with single-molecule fluorescence spectra of DsRed suggest that these new forms possibly originate from an extended chromophoric pi-system analogous to the DsRed chromophore.
Optical Characterization of Paper Aging Based on Laser-Induced Fluorescence (LIF) Spectroscopy.

PubMed

Zhang, Hao; Wang, Shun; Chang, Keke; Sun, Haifeng; Guo, Qingqian; Ma, Liuzheng; Yang, Yatao; Zou, Caihong; Wang, Ling; Hu, Jiandong

2018-06-01

Paper aging and degradation are growing concerns for those who are responsible for the conservation of documents, archives, and libraries. In this study, the paper aging was investigated using laser-induced fluorescence spectroscopy (LIFS), where the fluorescence properties of 47 paper samples with different ages were explored. The paper exhibits fluorescence in the blue-green spectral region with two peaks at about 448 nm and 480 nm under the excitation of 405 nm laser. Both fluorescence peaks changed in absolute intensities and thus the ratio of peak intensities was also influenced with the increasing ages. By applying principal component analysis (PCA) and k-means clustering algorithm, all 47 paper samples were classified into nine groups based on the differences in paper age. Then the first-derivative fluorescence spectral curves were proposed to figure out the relationship between the spectral characteristic and the paper age, and two quantitative models were established based on the changes of first-derivative spectral peak at 443 nm, where one is an exponential fitting curve with an R-squared value of 0.99 and another is a linear fitting curve with an R-squared value of 0.88. The results demonstrated that the combination of fluorescence spectroscopy and PCA can be used for the classification of paper samples with different ages. Moreover, the first-derivative fluorescence spectral curves can be used to quantitatively evaluate the age-related changes of paper samples.
Turn-off fluorescence sensor for the detection of ferric ion in water using green synthesized N-doped carbon dots and its bio-imaging.

PubMed

Edison, Thomas Nesakumar Jebakumar Immanuel; Atchudan, Raji; Shim, Jae-Jin; Kalimuthu, Senthilkumar; Ahn, Byeong-Cheol; Lee, Yong Rok

2016-05-01

This paper reports turn-off fluorescence sensor for Fe(3+) ion in water using fluorescent N-doped carbon dots as a probe. A simple and efficient hydrothermal carbonization of Prunus avium fruit extract for the synthesis of fluorescent nitrogen-doped carbon dots (N-CDs) is described. This green approach proceeds quickly and provides good quality N-CDs. The mean size of synthesized N-CDs was approximately 7nm calculated from the high-resolution transmission electron microscopic images. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy revealed the presence of -OH, -NH2, -COOH, and -CO functional groups over the surface of CDs. The N-CDs showed excellent fluorescent properties, and emitted blue fluorescence at 411nm upon excitation at 310nm. The calculated quantum yield of the synthesized N-CDs is 13% against quinine sulfate as a reference fluorophore. The synthesized N-CDs were used as a fluorescent probe towards the selective and sensitive detection of biologically important Fe(3+) ions in water by fluorescence spectroscopy and for bio-imaging of MDA-MB-231 cells. The limit of detection (LOD) and the Stern-Volmer quenching constant for the synthesized N-CDs were 0.96μM and 2.0958×10(3)M of Fe(3+) ions. The green synthesized N-CDs are efficiently used as a promising candidate for the detection of Fe(3+) ions and bio-imaging. Copyright © 2016 Elsevier B.V. All rights reserved.
ALA-induced PpIX spectroscopy for brain tumor image-guided surgery

NASA Astrophysics Data System (ADS)

Valdes, Pablo A.; Leblond, Frederic; Kim, Anthony; Harris, Brent T.; Wilson, Brian C.; Paulsen, Keith D.; Roberts, David W.

2011-03-01

Maximizing the extent of brain tumor resection correlates with improved survival and quality of life outcomes in patients. Optimal surgical resection requires accurate discrimination between normal and abnormal, cancerous tissue. We present our recent experience using quantitative optical spectroscopy in 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) fluorescence-guided resection. Exogenous administration of ALA leads to preferential accumulation in tumor tissue of the fluorescent compound, PpIX, which can be used for in vivo surgical guidance. Using the state of the art approach with a fluorescence surgical microscope, we have been able to visualize a subset of brain tumors, but the sensitivity and accuracy of fluorescence detection for tumor tissue with this system are low. To take full advantage of the biological selectivity of PpIX accumulation in brain tumors, we used a quantitative optical spectroscopy system for in vivo measurements of PpIX tissue concentrations. We have shown that, using our quantitative approach for determination of biomarker concentrations, ALA-induced PpIX fluorescence-guidance can achieve accuracies of greater than 90% for most tumor histologies. Here we show multivariate analysis of fluorescence and diffuse reflectance signals in brain tumors with comparable diagnostic performance to our previously reported quantitative approach. These results are promising, since they show that technological improvements in current fluorescence-guided surgical technologies and more biologically relevant approaches are required to take full advantage of fluorescent biomarkers, achieve better tumor identification, increase extent of resection, and subsequently, lead to improve survival and quality of life in patients.
Two-site ionic labeling with pyranine: implications for structural dynamics studies of polymers and polypeptides by time-resolved fluorescence anisotropy.

PubMed

Sharma, Jai; Tleugabulova, Dina; Czardybon, Wojciech; Brennan, John D

2006-04-26

Time-resolved fluorescence anisotropy (TRFA) is widely used to study dynamic motions of biomolecules in a variety of environments. However, depolarization due to rapid side chain motions often complicates the interpretation of anisotropy decay data and interferes with the accurate observation of segmental motions. Here, we demonstrate a new method for two-point ionic labeling of polymers and biomolecules that have appropriately spaced amino groups using the fluorescent probe 8-hydroxyl-1,3,6-trisulfonated pyrene (pyranine). TRFA analysis shows that such labeling provides a more rigid attachment of the fluorophore to the macromolecule than the covalent or single-point ionic labeling of amino groups, leading to time-resolved anisotropy decays that better reflect the backbone motion of the labeled polymer segment. Optimal coupling of pyranine to biomolecule dynamics is shown to be obtained for appropriately spaced Arg groups, and in such cases the ionic binding is stable up to 150 mM ionic strength. TRFA was used to monitor the behavior of pyranine-labeled poly(allylamine) (PAM) and poly-d-lysine (PL) in sodium silicate derived sol-gel materials and revealed significant restriction of backbone motion upon entrapment for both polymers, an observation that was not readily apparent in a previous study with entrapped fluorescein-labeled PAM and PL. The implications of these findings for fluorescence studies of polymer and biomolecule dynamics are discussed.
Diurnal Variability in Chlorophyll-a, Carotenoids, CDOM and SO₄(2-) Intensity of Offshore Seawater Detected by an Underwater Fluorescence-Raman Spectral System.

PubMed

Chen, Jing; Ye, Wangquan; Guo, Jinjia; Luo, Zhao; Li, Ying

2016-07-13

A newly developed integrated fluorescence-Raman spectral system (λex = 532 nm) for detecting Chlorophyll-a (chl-a), Chromophoric Dissolved Organic Matter (CDOM), carotenoids and SO₄(2-) in situ was used to successfully investigate the diurnal variability of all above. Simultaneously using the integration of fluorescence spectroscopy and Raman spectroscopy techniques provided comprehensive marine information due to the complementarity between the different excitation mechanisms and different selection rules. The investigation took place in offshore seawater of the Yellow Sea (36°05'40'' N, 120°31'32'' E) in October 2014. To detect chl-a, CDOM, carotenoids and SO₄(2-), the fluorescence-Raman spectral system was deployed. It was found that troughs of chl-a and CDOM fluorescence signal intensity were observed during high tides, while the signal intensity showed high values with larger fluctuations during ebb-tide. Chl-a and carotenoids were influenced by solar radiation within a day cycle by different detection techniques, as well as displaying similar and synchronous tendency. CDOM fluorescence cause interference to the measurement of SO₄(2-). To avoid such interference, the backup Raman spectroscopy system with λex = 785 nm was employed to detect SO₄(2-) concentration on the following day. The results demonstrated that the fluorescence-Raman spectral system has great potential in detection of chl-a, carotenoids, CDOM and SO₄(2-) in the ocean.
Fluorescence spectroscopy in the visible range for the assessment of UVB radiation effects in hairless mice skin.

PubMed

de Paula Campos, Carolina; de Paula D'Almeida, Camila; Nogueira, Marcelo Saito; Moriyama, Lilian Tan; Pratavieira, Sebastião; Kurachi, Cristina

2017-12-01

Ultraviolet (UV) radiation may induce skin alterations as observed in photoaging. Some recognized modifications are epidermal hyperplasia, amorphous deposition of degraded elastic fibers and reduction in the number of collagen fibers. They alter the tissue biochemical properties that can be interrogated by steady state fluorescence spectroscopy (SSFS). In this study, we monitored the changes in endogenous fluorescence emission from hairless mice skin during a protocol of photoaging using UVB irradiation. To perform the fluorescence spectroscopy, it was used a violet laser (408nm) to induce the native fluorescence that is emitted in the visible range. Under 408nm excitation, the emission spectrum showed bands with peaks centered around 510, 633 and 668nm for irradiated and control groups. A relative increase of the fluorescence at 633nm emission on the flank was observed with time when compared to the ventral skin at the same animal and the non-irradiated control group. We correlated the emission at 633nm with protoporphyrin IX (PpIX), and our hypothesis is that the PpIX metabolism in the photoaged and aged skin are different. PpIX fluorescence intensity in the photoaged skin is higher and more heterogeneous than in the aged skin. Notwithstanding, more spectroscopic and biochemistry studies investigating the 510 and 633nm emission are needed to confirm this hypothesis. Copyright © 2017 Elsevier B.V. All rights reserved.
Charge-transfer excited state in pyrene-1-carboxylic acids adsorbed on titanium dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Krawczyk, S.; Nawrocka, A.; Zdyb, A.

2018-06-01

The electronic structure of excited photosensitizer adsorbed at the surface of a solid is the key factor in the electron transfer processes that underlie the efficiency of dye-sensitized solar cells and photocatalysts. In this work, Stark effect (electroabsorption) spectroscopy has been used to measure the polarizability and dipole moment changes in electronic transitions of pyrene-1-carboxylic (PCA), -acetic (PAA) and -butyric (PBA) acids in ethanol, both free and adsorbed on colloidal TiO2, in glassy ethanol at low temperature. The lack of appreciable increase of dipole moment in the excited state of free and adsorbed PAA and PBA points that two or more single bonds completely prevent the expansion of π-electrons from the aromatic ring towards the carboxylic group, thus excluding the possibility of direct electron injection into TiO2. In free PCA, the pyrene's forbidden S0 → S1 transition has increased intensity, exhibits a long progression in 1400 cm-1 Ag mode and is associated with |Δμ| of 2 D. Adsorption of PCA on TiO2 causes a broadening and red shift of the S0 → S1 absorption band and an increase in dipole moment change on electronic excitation to |Δμ| = 6.5 D. This value increased further to about 15 D when the content of acetic acid in the colloid was changed from 0.2% to 2%, and this effect is ascribed to the surface electric field. The large increase of |Δμ| points that the electric field effect can not only change the energetics of electron transfer from the excited sensitizer into the solid, but can also shift the molecular electronic density, thus directly influencing the electronic coupling factor relevant for electron transfer at the molecule-solid interface.
Photo-dynamics of roseoflavin and riboflavin in aqueous and organic solvents

NASA Astrophysics Data System (ADS)

Zirak, P.; Penzkofer, A.; Mathes, T.; Hegemann, P.

2009-03-01

Roseoflavin (8-dimethylamino-8-demethyl- D-riboflavin) and riboflavin in aqueous and organic solvents are studied by optical absorption spectroscopy, fluorescence spectroscopy, and fluorescence decay kinetics. Solvent polarity dependent absorption shifts are observed. The fluorescence quantum yields are solvent dependent. For roseoflavin the fluorescence decay shows a bi-exponential dependence (ps to sub-ps time constant, and 100 ps to a few ns time constant). The roseoflavin photo-dynamics is explained in terms of fast intra-molecular charge transfer (diabatic electron transfer) from the dimethylamino electron donor group to the pteridin carbonyl electron acceptor followed by intra-molecular charge recombination. The fast fluorescence component is due to direct locally-excited-state emission, and the slow fluorescence component is due to delayed locally-excited-state emission and charge transfer state emission. The fluorescence decay of riboflavin is mono-exponential. The S 1-state potential energy surface is determined by vibronic relaxation and solvation dynamics due to excited-state dipole moment changes (adiabatic optical electron transfer).
Assessment of the quality attributes of cod caviar paste by means of front-face fluorescence spectroscopy.

PubMed

Airado-Rodríguez, Diego; Skaret, Josefine; Wold, Jens Petter

2010-05-12

This paper describes the fluorescent behavior of cod caviar paste, stored under different conditions, in terms of light exposure and concentration of oxygen in the headspace. Multivariate curve resolution was employed to decompose the overall fluorescence spectra into pure fluorescent components and calculate the relative concentrations of these components in the different samples. Profiles corresponding to protoporphyrin IX, photoprotoporphyrin, and fluorescent oxidation products were identified. Sensory evaluation, TBARS, and analysis of volatiles are typical methods employed in the routine analysis and quality control of such food. Successful calibration models were established between fluorescence and those routine methods. Correlation coefficients higher than 0.80 were found for 79% and higher than 0.90 for 50% of the assessed odors and flavors. For instance, R values of 0.94, and 0.96 were obtained for fresh and rancid flavors respectively, and 0.89 for TBARS. On the basis of these data, it can be argued that front-face fluorescence spectroscopy can substitute all of these expensive and tedious methodologies.
Surface Transient Binding-Based Fluorescence Correlation Spectroscopy (STB-FCS), a Simple and Easy-to-Implement Method to Extend the Upper Limit of the Time Window to Seconds.

PubMed

Peng, Sijia; Wang, Wenjuan; Chen, Chunlai

2018-05-10

Fluorescence correlation spectroscopy is a powerful single-molecule tool that is able to capture kinetic processes occurring at the nanosecond time scale. However, the upper limit of its time window is restricted by the dwell time of the molecule of interest in the confocal detection volume, which is usually around submilliseconds for a freely diffusing biomolecule. Here, we present a simple and easy-to-implement method, named surface transient binding-based fluorescence correlation spectroscopy (STB-FCS), which extends the upper limit of the time window to seconds. We further demonstrated that STB-FCS enables capture of both intramolecular and intermolecular kinetic processes whose time scales cross several orders of magnitude.
Host-guest inclusion system of ferulic acid with p-Sulfonatocalix[n]arenes: Preparation, characterization and antioxidant activity

NASA Astrophysics Data System (ADS)

Chao, Jianbin; Wang, Huijuan; Song, Kailun; Wang, Yongzhao; Zuo, Ying; Zhang, Liwei; Zhang, Bingtai

2017-02-01

The inclusion complexes of ferulic acid (FA) with p-Sulfonatocalix[n]arenes (SCXn, n = 4, 6, 8) were prepared and characterized both in the solid state and in solution using fluorescence spectroscopy, 1H nuclear magnetic resonance (1H NMR), attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM) and differential scanning calorimetry (DSC). The results show that FA is able to form inclusion complexes with SCXn in a molar ratio of 1:1, causing a significant decrease in the fluorescence intensity of FA. The association constant of the inclusion complexes was calculated from the fluorescence titration data. 1H NMR spectroscopy analysis demonstrates that the aromatic ring and methoxy group of FA are partially covered by SCXn.
Elucidation of intermolecular interaction of bovine serum albumin with Fenhexamid: A biophysical prospect.

PubMed

Shi, Jie-Hua; Lou, Yan-Yue; Zhou, Kai-Li; Pan, Dong-Qi

2018-03-01

Fenhexamid, as a hydroxyanilide, is widely applied to control Botrytis cinerea for protecting crops and fruits. But it could adversely affect human and animals health due to accumulation of residues in food production. Here, the affinity characteristics of fenhexamid on bovine serum albumin (BSA) was studied via a series of spectroscopic methods such as steady-state fluorescence spectroscopy, ultraviolet spectroscopy (UV), synchronous fluorescence spectroscopy (SFS), 3D fluorescence spectroscopy, and fourier transform infrared spectroscopy (FT-IR). The experimental results illustrated that the fluorescence quenching mechanism of BSA induced by fenhexamid was a static quenching. The binding constant (K b ) of fenhexamid with BSA was 2.399 × 10 4  M -1 at 298 K and the combination ratio was about 1:1. The competitive experiment demonstrated that fenhexamid was binding on the BSA at site II (subdomain IIIA), which was confirmed by the molecular docking studies. The negative values of thermodynamic parameter (ΔH 0 , ΔS 0 and ΔG 0 ) revealed that the reaction of fenhexamid with BSA could proceed spontaneously, the van der Waals force and hydrogen bonding interaction conducted the main effect, and the binding process was enthalpy-driven. What's more, the 8-Anilino-1-naphthalenesulfonate (ANS) and sucrose binding studies were also performed and further verified the binding force between BSA and fenhexamid. Copyright © 2018 Elsevier B.V. All rights reserved.
Spectroscopy: An Introduction for Talented High School Students.

ERIC Educational Resources Information Center

Magyar, Elaine; Magyar, James G.

1989-01-01

Investigates the four week chemistry program in a summer program in science and mathematics. Identifies weekly topics for the program: (1) color and visible spectroscopy; (2) UV spectroscopy, fluorescence, and chemiluminescence; (3) IR and NMR spectroscopy; and (4) lists 12 individual projects. (MVL)
Nondestructive application of laser-induced fluorescence spectroscopy for quantitative analyses of phenolic compounds in strawberry fruits (Fragaria x ananassa).

PubMed

Wulf, J S; Rühmann, S; Rego, I; Puhl, I; Treutter, D; Zude, M

2008-05-14

Laser-induced fluorescence spectroscopy (LIFS) was nondestructively applied on strawberries (EX = 337 nm, EM = 400-820 nm) to test the feasibility of quantitatively determining native phenolic compounds in strawberries. Eighteen phenolic compounds were identified in fruit skin by UV and MS spectroscopy and quantitatively determined by use of rp-HPLC for separation and diode-array or chemical reaction detection. Partial least-squares calibration models were built for single phenolic compounds by means of nondestructively recorded fluorescence spectra in the blue-green wavelength range using different data preprocessing methods. The direct orthogonal signal correction resulted in r (2) = 0.99 and rmsep < 8% for p-coumaroyl-glucose, and r (2) = 0.99 and rmsep < 24% for cinnamoyl-glucose. In comparison, the correction of the fluorescence spectral data with simultaneously recorded reflectance spectra did not further improve the calibration models. Results show the potential of LIFS for a rapid and nondestructive assessment of contents of p-coumaroyl-glucose and cinnamoyl-glucose in strawberry fruits.
Highly photostable "super"-photoacids for ultrasensitive fluorescence spectroscopy.

PubMed

Finkler, Björn; Spies, Christian; Vester, Michael; Walte, Frederick; Omlor, Kathrin; Riemann, Iris; Zimmer, Manuel; Stracke, Frank; Gerhards, Markus; Jung, Gregor

2014-03-01

The photoacid 8-hydroxypyren-1,3,6-trisulfonic acid (HPTS, pyranine) is a widely used model compound for the examination of excited state proton transfer (ESPT). We synthesized five "super"-photoacids with varying hydrophilicity and acidity on the basis of HPTS. By chemical modification of the three sulfonic acid substituents, the photoacidity is enhanced by up to more than five logarithmic units from pK*≈ 1.4 to ∼-3.9 for the most acidic compound. As a result, nearly quantitative ESPT in DMSO can be observed. The novel photoacids were characterized by steady-state and time-resolved fluorescence techniques showing distinctively red shifted spectra compared to HPTS while maintaining a high quantum yield near 90%. Photostability of the compounds was checked by fluorescence correlation spectroscopy (FCS) and was found to be adequately high for ultrasensitive fluorescence spectroscopy. The described photoacids present a valuable palette for a wide range of applications, especially when the properties of HPTS, i.e. highly charged, low photostability and only moderate excited state acidity, are limiting.
New Approaches in Soil Organic Matter Fluorescence; A Solid Phase Fluorescence Approach

NASA Astrophysics Data System (ADS)

Bowman, M. M.; Sanclements, M.; McKnight, D. M.

2017-12-01

Fluorescence spectroscopy is a well-established technique to investigate the composition of organic matter in aquatic systems and is increasingly applied to soil organic matter (SOM). Current methods require that SOM be extracted into a liquid prior to analysis by fluorescence spectroscopy. Soil extractions introduce an additional layer of complexity as the composition of the organic matter dissolved into solution varies based upon the selected extractant. Water is one of the most commonly used extractant, but only extracts the water-soluble fraction of the SOM with the insoluble soil organic matter fluorescence remaining in the soil matrix. We propose the use of solid phase fluorescence on whole soils as a potential tool to look at the composition of organic matter without the extraction bias and gain a more complete understand of the potential for fluorescence as a tool in terrestrial studies. To date, the limited applications of solid phase fluorescence have ranged from food and agriculture to pharmaceutical with no clearly defined methods and limitations available. We are aware of no other studies that use solid phase fluorescence and thus no clear methods to look at SOM across a diverse set of soil types and ecosystems. With this new approach to fluorescence spectroscopy there are new challenges, such as blank correction, inner filter effect corrections, and sample preparation. This work outlines a novel method for analyzing soil organic matter using solid phase fluorescence across a wide range of soils collected from the National Ecological Observatory Network (NEON) eco-domains. This method has shown that organic matter content in soils must be diluted to 2% to reduce backscattering and oversaturation of the detector in forested soils. In mineral horizons (A) there is observed quenching of the humic-like organic matter, which is likely a result of organo-mineral complexation. Finally, we present preliminary comparisons between solid and liquid phase fluorescence, which provide new insights into fluorescence studies in terrestrial systems.

Assessing the photoaging process at sun exposed and non-exposed skin using fluorescence lifetime spectroscopy

NASA Astrophysics Data System (ADS)

Saito Nogueira, Marcelo; Kurachi, Cristina

2016-03-01

Photoaging is the skin premature aging due to exposure to ultraviolet light, which damage the collagen, elastin and can induce alterations on the skin cells DNA, and, then, it may evolve to precancerous lesions, which are widely investigated by fluorescence spectroscopy and lifetime. The fluorescence spectra and fluorescence lifetime analysis has been presented as a technique of great potential for biological tissue characterization at optical diagnostics. The main targeted fluorophores are NADH (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide), which have free and bound states, each one with different average lifetimes. The average lifetimes for free and bound NADH and FAD change according to tissue metabolic alterations and may contribute to a non-invasive clinical investigation of injuries such as skin lesions. These lesions and the possible areas where they may develop can be interrogated using fluorescence lifetime spectroscopy taking into account the variability of skin phototypes and the changes related to melanin, collagen and elastin, endogenous fluorophores which have emissions that spectrally overlap to the NADH and FAD emission. The objective of this study is to assess the variation on fluorescence lifetimes of normal skin at sun exposed and non-exposed areas and associate this variation to the photoaging process.
Facile preparation of fluorescent layered double hydroxide polymeric composites through the photo-induced surface-initiated controlled living polymerization

NASA Astrophysics Data System (ADS)

Chen, Junyu; Liu, Meiying; Huang, Qiang; Jiang, Ruming; Huang, Hongye; Deng, Fengjie; Wen, Yuanqing; Tian, Jianwen; Zhang, Xiaoyong; Wei, Yen

2018-05-01

(Zn/Al) layered double hydroxide (LDH) based fluorescence probes have been facilely fabricated via photo-induced surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, which demonstrated green fluorescence, good biocompatibility and excellent dispersion performance in aqueous solution. The as prepared (Zn/Al)LDH polymeric composites were modified with 2-methacryloyloxyethyl phosphorylcholine (MPC), acrylic acid (AA) and diacroloyl-fluorescein (Ac-Fl). Among them, the comonomers MPC and AA were used to endow their water dispersibility, biocompatibility and potential drug carriers, while the Ac-Fl was served both as the fluorescence signal and photocatalyst for RAFT polymerization. A series of characterization methods, including 1H nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, transmission electronic microscopy, thermogravimetric analyses, X-ray photoelectron spectroscopy were employed to conform the successful of surface modification of LDH through photo-induced surface-initiated RAFT polymerization. Besides, UV-vis absorption spectra and fluorescence spectra were adopted to evaluate the optical characteristics of as prepared (Zn/Al)LDH-co-Poly(MPC-AA-Fl) composites, which exhibited high intense green fluorescence. Furthermore, the endocytosis behavior indicates that (Zn/Al)LDH-co-Poly(MPC-AA-Fl) composites could be potentially used in cell imaging and even drug delivery application for their excellent biocompatibility and all advantages described above.
Choosing the right fluorophore for single-molecule fluorescence studies in a lipid environment.

PubMed

Zhang, Zhenfu; Yomo, Dan; Gradinaru, Claudiu

2017-07-01

Nonspecific interactions between lipids and fluorophores can alter the outcomes of single-molecule spectroscopy of membrane proteins in live cells, liposomes or lipid nanodiscs and of cytosolic proteins encapsulated in liposomes or tethered to supported lipid bilayers. To gain insight into these effects, we examined interactions between 9 dyes that are commonly used as labels for single-molecule fluorescence (SMF) and 6 standard lipids including cationic, zwitterionic and anionic types. The diffusion coefficients of dyes in the absence and presence of set amounts of lipid vesicles were measured by fluorescence correlation spectroscopy (FCS). The partition coefficients and the free energies of partitioning for different fluorophore-lipid pairs were obtained by global fitting of the titration FCS curves. Lipids with different charges, head groups and degrees of chain saturation were investigated, and interactions with dyes are discussed in terms of hydrophobic, electrostatic and steric contributions. Fluorescence imaging of individual fluorophores adsorbed on supported lipid bilayers provides visualization and additional quantification of the strength of dye-lipid interaction in the context of single-molecule measurements. By dissecting fluorophore-lipid interactions, our study provides new insights into setting up single-molecule fluorescence spectroscopy experiments with minimal interference from interactions between fluorescent labels and lipids in the environment. Copyright © 2017 Elsevier B.V. All rights reserved.
Methylglyoxal induced glycation and aggregation of human serum albumin: Biochemical and biophysical approach.

PubMed

Ahmed, Azaj; Shamsi, Anas; Khan, Mohd Shahnawaz; Husain, Fohad Mabood; Bano, Bilqees

2018-07-01

Serum protein glycation and formation of advanced glycation end products (AGEs) correlates with many diseases viz. diabetes signifying the importance of studying the glycation pattern of serum proteins. In our present study, methylglyoxal was investigated for its effect on the structure of human serum albumin (HSA); exploring the formation of AGEs and aggregates of HSA. The analytical tools employed includes intrinsic and extrinsic fluorescence, UV spectroscopy, far UV circular dichroism, Thioflavin T fluorescence, congo red binding, polyacrylamide gel electrophoresis (PAGE). UV and fluorescence spectroscopy revealed the structural transition of native HSA evident by new peaks and increased absorbance in UV spectra and quenched fluorescence in the presence of MG. Far UV CD spectroscopy revealed MG induced secondary structural alteration evident by reduced α-helical content. AGEs formation was confirmed by AGEs specific fluorescence. Increased ThT fluorescence and CR absorbance of 10mM MG incubated HSA suggests that glycated HSA results in the formation of aggregates of HSA. SEM and TEM were reported to have an insight of these aggregates. Molecular docking was also utilized to see site specific interaction of MG-HSA. This study is clinically significant as HSA is a clinically relevant protein which plays a crucial role in many diseases. Copyright © 2018 Elsevier B.V. All rights reserved.
Benzo(a)pyrene diol epoxides as intermediates in nucleic acid binding in vitro and in vivo.

PubMed

Weinstein, I B; Jeffrey, A M; Jennette, K W; Blobstein, S H; Harvey, R G; Harris, C; Autrup, H; Kasai, H; Nakanishi, K

1976-08-13

Evidence has been obtained that a specific isomer of a diol epoxide derivative of benzo(a)pyrene, (+/-)-7 beta,8alpha-dihydroxy-9alpha, 10alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene, is an intermediate in the binding of benzo(a)pyrene to RNA in cultured bovine bronchial mucosa. An adduct is formed between position 10 of this derivative and the 2-amino group of guanine.
Pyrene Molecular Orbital Shuffle-Controlling Excited State and Redox Properties by Changing the Nature of the Frontier Orbitals.

PubMed

Merz, Julia; Fink, Julian; Friedrich, Alexandra; Krummenacher, Ivo; Al Mamari, Hamad H; Lorenzen, Sabine; Haehnel, Martin; Eichhorn, Antonius; Moos, Michael; Holzapfel, Marco; Braunschweig, Holger; Lambert, Christoph; Steffen, Andreas; Ji, Lei; Marder, Todd B

2017-09-21

We show that by judicious choice of substituents at the 2- and 7-positions of pyrene, the frontier orbital order of pyrene can be modified, giving enhanced control over the nature and properties of the photoexcited states and the redox potentials. Specifically, we introduced a julolidine-like moiety and Bmes 2 (mes=2,4,6-Me 3 C 6 H 2 ) as very strong donor (D) and acceptor (A), respectively, giving 2,7-D-π-D- and unsymmetric 2,7-D-π-A-pyrene derivatives, in which the donor destabilizes the HOMO-1 and the acceptor stabilizes the LUMO+1 of the pyrene core. Consequently, for 2,7-substituted pyrene derivatives, unusual properties are obtained. For example, very large bathochromic shifts were observed for all of our compounds, and unprecedented green light emission occurs for the D/D system. In addition, very high radiative rate constants in solution and in the solid state were recorded for the D-π-D- and D-π-A-substituted compounds. All compounds show reversible one-electron oxidations, and Jul 2 Pyr exhibits a second oxidation, with the largest potential splitting (ΔE=440 mV) thus far reported for 2,7-substituted pyrenes. Spectroelectrochemical measurements confirm an unexpectedly strong coupling between the 2,7-substituents in our pyrene derivatives. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Quantification of tumor fluorescence during intraoperative optical cancer imaging

PubMed Central

Judy, Ryan P.; Keating, Jane J.; DeJesus, Elizabeth M.; Jiang, Jack X.; Okusanya, Olugbenga T.; Nie, Shuming; Holt, David E.; Arlauckas, Sean P.; Low, Phillip S.; Delikatny, E. James; Singhal, Sunil

2015-01-01

Intraoperative optical cancer imaging is an emerging technology in which surgeons employ fluorophores to visualize tumors, identify tumor-positive margins and lymph nodes containing metastases. This study compares instrumentation to measure tumor fluorescence. Three imaging systems (Spectropen, Glomax, Flocam) measured and quantified fluorescent signal-to-background ratios (SBR) in vitro, murine xenografts, tissue phantoms and clinically. Evaluation criteria included the detection of small changes in fluorescence, sensitivity of signal detection at increasing depths and practicality of use. In vitro, spectroscopy was superior in detecting incremental differences in fluorescence than luminescence and digital imaging (Ln[SBR] = 6.8 ± 0.6, 2.4 ± 0.3, 2.6 ± 0.1, p = 0.0001). In fluorescent tumor cells, digital imaging measured higher SBRs than luminescence (6.1 ± 0.2 vs. 4.3 ± 0.4, p = 0.001). Spectroscopy was more sensitive than luminometry and digital imaging in identifying murine tumor fluorescence (SBR = 41.7 ± 11.5, 5.1 ± 1.8, 4.1 ± 0.9, p = 0.0001), and more sensitive than digital imaging at detecting fluorescence at increasing depths (SBR = 7.0 ± 3.4 vs. 2.4 ± 0.5, p = 0.03). Lastly, digital imaging was the most practical and least time-consuming. All methods detected incremental differences in fluorescence. Spectroscopy was the most sensitive for small changes in fluorescence. Digital imaging was the most practical considering its wide field of view, background noise filtering capability, and sensitivity to increasing depth. PMID:26563091
Co-effects of pyrene and nitrate on the activity and abundance of soil denitrifiers under anaerobic condition.

PubMed

Zhou, Zhi-Feng; Yao, Yan-Hong; Wang, Ming-Xia; Zuo, Xiao-Hu

2017-10-01

It has previously been confirmed that polycyclic aromatic hydrocarbons (PAHs) could be degraded by soil microbes coupling with denitrification, but the relationships among soil denitrifiers, PAHs, and nitrate under obligate anaerobic condition are still unclear. Here, co-effects of pyrene and nitrate on the activity and abundance of soil denitrifiers were investigated through a 45-day incubation experiment. Two groups of soil treatments with (N 30 ) and without (N 0 ) nitrate (30 mg kg -1 dry soil) amendment were conducted, and each group contained three treatments with different pyrene concentrations (0, 30, and 60 mg kg -1 dry soil denoted as P 0 , P 30 , and P 60 , respectively). The pyrene content, abundances of denitrification concerning genes (narG, periplasmic nitrate reductase gene; nirS, cd 1 -nitrite reductase gene; nirK, copper-containing nitrite reductase gene), and productions of N 2 O and CO 2 were measured at day 3, 14, 28, and 45, and the bacterial community structures in four represented treatments (N 0 P 0 , N 0 P 60 , N 30 P 0 , and N 30 P 60 ) were analyzed at day 45. The results indicated that the treatments with higher pyrene concentration had higher final pyrene removal rates than the treatments with lower pyrene concentration. Additionally, intensive emission of N 2 O was detected in all treatments only at day 3, but a continuous production of CO 2 was measured in each treatment during the incubation. Nitrate amendment could enhance the activity of soil denitrifiers, and be helpful for soil microbes to sustain their activity. While pyrene seemed had no influence on the productions of N 2 O and CO 2 , and amendment with pyrene or nitrate both had no obvious effect on abundances of denitrification concerning genes. Furthermore, it was nitrate but not pyrene had an obvious influence on the community structure of soil bacteria. These results revealed that, under anaerobic condition, the activity and abundance of soil denitrifiers both were insensitive to pyrene, but nitrate could improve the activity of soil denitrfiers and induce the shifts in soil bacterial community structure.
Reduced cytochrome P4501A activity and recovery from oxidative stress during subchronic benzo[a]pyrene and benzo[e]pyrene treatment of rainbow trout

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curtis, Lawrence R., E-mail: larry.curtis@oregonstate.edu; Garzon, Claudia B.; Arkoosh, Mary

2011-07-01

This study assessed the role of aryl hydrocarbon receptor (AHR) affinity, and cytochrome P4501A (CYP1A) protein and activity in polyaromatic hydrocarbon (PAH)-induced oxidative stress. In the 1-100 nM concentration range benzo[a]pyrene (BaP) but not benzo[e]pyrene (BeP) competitively displaced 2 nM [{sup 3}H]2, 3, 7, 8-tetrachloro-dibenzo-p-dioxin from rainbow trout AHR2{alpha}. Based on appearance of fluorescent aromatic compounds in bile over 3, 7, 14, 28 or 50 days of feeding 3 {mu}g of BaP or BeP/g fish/day, rainbow trout liver readily excreted these polyaromatic hydrocarbons (PAHs) and their metabolites at near steady state rates. CYP1A proteins catalyzed more than 98% of ethoxyresorufin-O-deethylasemore » (EROD) activity in rainbow trout hepatic microsomes. EROD activity of hepatic microsomes initially increased and then decreased to control activities after 50 days of feeding both PAHs. Immunohistochemistry of liver confirmed CYP1A protein increased in fish fed both PAHs after 3 days and remained elevated for up to 28 days. Neither BaP nor BeP increased hepatic DNA adduct concentrations at any time up to 50 days of feeding these PAHs. Comet assays of blood cells demonstrated marked DNA damage after 14 days of feeding both PAHs that was not significant after 50 days. There was a strong positive correlation between hepatic EROD activity and DNA damage in blood cells over time for both PAHs. Neither CYP1A protein nor 3-nitrotyrosine (a biomarker for oxidative stress) immunostaining in trunk kidney were significantly altered by BaP or BeP after 3, 7, 14, or 28 days. There was no clear association between AHR2{alpha} affinity and BaP and BeP-induced oxidative stress. - Highlights: > No direct association between aryl hydrocarbon receptor affinity and polyaromatic hydrocarbon induced oxidative stress. > There was a strong correlation between cytochrome P4501A activity and oxidative stress as measured with the comet assay. > There was no correlation between cytochrome P4501A protein and oxidative stress as measured with the comet assay.« less
One-step synthesis of fluorescein modified nano-carbon for Pd(II) detection via fluorescence quenching.

PubMed

Panchompoo, Janjira; Aldous, Leigh; Baker, Matthew; Wallace, Mark I; Compton, Richard G

2012-05-07

Carbon black (CB) nanoparticles modified with fluorescein, a highly fluorescent molecule, were prepared using a facile and efficient methodology. Simply stirring CB in aqueous solution containing fluorescein resulted in the strong physisorption of fluorescein onto the CB surface. The resulting Fluorescein/CB was then characterised by means of X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), fluorescence microscopy and fluorescence spectroscopy. The optimum experimental conditions for fluorescence of Fluorescein/CB viz. fluorescence excitation and emission wavelengths, O(2) removal and the amount of Fluorescein/CB used, were investigated. The Fluorescein/CB was used as a fluorescent probe for the sensitive detection of Pd(II) in water, based on fluorescence quenching. The results demonstrated that the fluorescence intensity of Fluorescein/CB decreased with increasing Pd(II) concentration, and the fluorescence quenching process could be described by the Stern-Volmer equation. The limit of detection (LOD) for the fluorescence quenching of Fluorescein/CB by Pd(II) in aqueous solution was found to be 1.07 μM (based on 3σ). Last, approaches were studied for the removal of Fe(III) which interferes with the fluorescence quenching of Fluorescein/CB. Complexation of Fe(III) with salicylic acid was used to enhance and control the selectivity of Fluorescein/CB sensor towards Pd(II) in the presence of Fe(III).
Probing the chemical environments of early star formation: A multidisciplinary approach

NASA Astrophysics Data System (ADS)

Hardegree-Ullman, Emily Elizabeth

Chemical compositions of prestellar and protostellar environments in the dense interstellar medium are best quantified using a multidisciplinary approach. For my dissertation, I completed two projects to measure molecular abundances during the earliest phases of star formation. The first project investigates gas phase CO depletion in molecular cloud cores, the progenitors of star systems, using infrared photometry and molecular line spectroscopy at radio wavelengths. Hydrogenation of CO depleted onto dust is an important first step toward building complex organic molecules. The second project constrains polycyclic aromatic hydrocarbon (PAH) abundances toward young stellar objects (YSO). Band strengths measured from laboratory spectroscopy of pyrene/water ice mixtures were applied to estimate abundances from features attributed to PAHs in observational YSO spectra. PAHs represent a distinct but important component of interstellar organic material that is widely observed but not well quantified in star-forming regions.
Pyrene and benzo[a]pyrene metabolism by the filamentous fungus, Penicillium janthinellum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Launen, L.; Pinto, L.; Kiehlmann, E.

1995-12-31

The incomplete combustion of fossil fuels generates polycyclic aromatic hydrocarbons (PAH). These include 4-5 ring PAH, of which many are potent carcinogens and mutagens that persist in soil for years. Fungi can oxidize these compounds via two mechanisms: (1) by extracellular peroxidases (Basidiomycete fungi), or (2) by a putative cytochrome P450 enzyme system. The authors have previously isolated Penicillium janthinellum from petroleum-contaminated soil and shown that it possesses high activity to oxidize pyrene, benzo(a)pyrene and chrysene in liquid culture. The purpose of this study was to evaluate the effect of changing growth condition glucose, nitrate and agitation levels, on pyrenemore » metabolism by P. janthinellum using a 3 x 2 x 2 factorial design. Spores were inoculated into minimal salts media amended with varying carbon or nitrogen concentrations and containing {sup 14}C-pyrene. The level of glucose and nitrate significantly affected the bioconversion: low glucose and nitrate levels increased the loss of parent PAH from the medium. However this effect was independent of biomass. Biometer flask experiments using {sup 14}C-pyrene showed that most pyrene became cell-associated within 7 days of incubation. Cell associated {sup 14}C-pyrene was inextractable by ethyl acetate but was recovered in methylene chloride. This result was confirmed by the mass balance result from a 10 day time course experiment using {sup 14}C-pyrene or {sup 14}C-BaP. Greater than 70% of the radiolabel in cultures containing live cells was strongly associated with the cell matter within 7 days, relative to < 1 % association with dead cells. The authors conclude that: (1) pyrene and BaP oxidation was affected by C and N levels in the growth medium independent of cell mass and (2) {sup 14}C-PAH became strongly associated with live but not dead cells within 7 days in liquid culture.« less
Automobile tires--a potential source of highly carcinogenic dibenzopyrenes to the environment.

PubMed

Sadiktsis, Ioannis; Bergvall, Christoffer; Johansson, Christer; Westerholm, Roger

2012-03-20

Eight tires were analyzed for 15 high molecular weight (HMW) polycyclic aromatic hydrocarbons (PAH), using pressurized fluid extraction. The variability of the PAH concentrations determined between different tires was large; a factor of 22.6 between the lowest and the highest. The relative abundance of the analytes was quite similar regardless of tire. Almost all (92.3%) of the total extractable PAH content was attributed to five PAHs: benzo[ghi]perylene, coronene, indeno[1,2,3-cd]pyrene, benzo[e]pyrene, and benzo[a]pyrene. The difference in the measured PAH content between summer and winter tires varied substantially across manufacturers, making estimates of total vehicle fleet emissions very uncertain. However, when comparing different types of tires from the same manufacturer they had significantly (p = 0.05) different PAH content. Previously, there have been no data available for carcinogenic dibenzopyrene isomers in automobile tires. In this study, the four dibenzopyrene isomers dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene, and dibenzo[a,h]pyrene constituted <2% of the sum of the 15 analyzed HMW PAHs. These findings show that automobile tires may be a potential previously unknown source of carcinogenic dibenzopyrenes to the environment.
Cellular deficiency of Werner Syndrome protein or RECQ1 promotes genotoxic potential of hydroquinone and benzo[a]pyrene exposure

PubMed Central

Garige, Mamatha; Sharma, Sudha

2014-01-01

The five known RecQ helicases in humans (RECQ1, BLM, WRN, RECQL4, and RECQ5) have demonstrated roles in diverse genome maintenance mechanisms but their functions in safeguarding the genome from environmental toxicants are poorly understood. Here, we have evaluated a potential role of WRN (mutated in Werner Syndrome) and RECQ1 (the most abundant homolog of WRN) in hydroquinone and benzo[a]pyrene-induced genotoxicity. Silencing of WRN or RECQ1 expression in HeLa cells increased their sensitivity to hydroquinone and benzo[a]pyrene but elicited distinct DNA damage response. RECQ1-depleted cells exhibited increased RPA phosphorylation, Chk1 activation, and DNA double strand breaks as compared to control or WRN-depleted cells following exposure to benzo[a]pyrene treatment. Benzo[a]pyrene-induced double strand breaks in RECQ1-depleted cells were dependent on DNA-PK activity. Notably, loss of WRN in RECQ1-depleted cells ameliorated benzo[a]pyrene toxicity. Collectively, our results provide first indication of non-redundant participation of WRN and RECQ1 in protection from the potentially carcinogenic effects of benzo[a]pyrene and hydroquinone. PMID:25228686
Spectroscopic studies on the interaction of fluorescein and safranine T in PC liposomes

NASA Astrophysics Data System (ADS)

Bozkurt, Ebru; Bayraktutan, Tuğba; Acar, Murat; Toprak, Mahmut

2013-01-01

In this study, the fluorescence quenching of fluorescein by safranine T in liposome media had been investigated systematically by fluorescence spectroscopy, UV-vis absorption spectroscopy and fluorescence decay lifetime measurements. The spectroscopic data were analyzed using a Stern-Volmer equation to determine the quenching process. The experimental results showed that the intrinsic fluorescence of fluorescein was strongly quenched by safranine T, and that the quenching mechanism was considered as static quenching by forming a ground-complex. The Stern-Volmer quenching constant Ksv, and the bimolecular quenching constant Kq were estimated. The distances between the donor (fluorescein) and the acceptor (safranine T) were calculated according to the Förster non-radiation energy transfer theory. In addition, the partition coefficient of the safranine T (Kp) in the L-egg lecithin phosphatidylcholine liposomes was also calculated by utilizing the fluorescence quenching.
Detection and evaluation of normal and malignant cells using laser-induced fluorescence spectroscopy.

PubMed

Khosroshahi, Mohamad E; Rahmani, Mahya

2012-01-01

The aim of this research is to study the normalized fluorescence spectra (intensity variations and area under the fluorescence signal), relative quantum yield, extinction coefficient and intracellular properties of normal and malignant human bone cells. Using Laser-Induced Fluorescence Spectroscopy (LIFS) upon excitation of 405 nm, the comparison of emission spectra of bone cells revealed that fluorescence intensity and the area under the spectra of malignant bone cells was less than that of normal. In addition, the area ratio and shape factor were changed. We obtained two emission bands in spectra of normal cells centered at about 486 and 575 nm and for malignant cells about 482 and 586 nm respectively, which are most likely attributed to NADH and riboflavins. Using fluorescein sodium emission spectrum, the relative quantum yield of bone cells is numerically determined.
Photophysical Behaviors of Single Fluorophores Localized on Zinc Oxide Nanostructures

PubMed Central

Fu, Yi; Zhang, Jian; Lakowicz, Joseph R.

2012-01-01

Single-molecule fluorescence spectroscopy has now been widely used to investigate complex dynamic processes which would normally be obscured in an ensemble-averaged measurement. In this report we studied photophysical behaviors of single fluorophores in proximity to zinc oxide nanostructures by single-molecule fluorescence spectroscopy and time-correlated single-photon counting (TCSPC). Single fluorophores on ZnO surfaces showed enhanced fluorescence brightness to various extents compared with those on glass; the single-molecule time trajectories also illustrated pronounced fluctuations of emission intensities, with time periods distributed from milliseconds to seconds. We attribute fluorescence fluctuations to the interfacial electron transfer (ET) events. The fluorescence fluctuation dynamics were found to be inhomogeneous from molecule to molecule and from time to time, showing significant static and dynamic disorders in the interfacial electron transfer reaction processes. PMID:23109903
IRIS Toxicological Review of Benzo[a]pyrene (Final Report)

EPA Science Inventory

EPA has finalized the Integrated Risk Information System (IRIS) assessment of benzo[a]pyrene. This assessment addresses the potential cancer and noncancer human health effects from long-term exposure to benzo[a]pyrene. Now final, this assessment will update the toxicological info...
Pyrene-Tagged Ionic Liquids: Separable Organic Catalysts for SN2 Fluorination.

PubMed

Taher, Abu; Lee, Kyo Chul; Han, Hye Ji; Kim, Dong Wook

2017-07-07

We prepared pyrene-substituted imidazolium-based ionic liquids (PILs) as organic catalysts for the S N 2 fluorination using alkali metal fluoride (MF). In this system, the PIL significantly enhanced the reactivity of MF due to the phase-transfer catalytic effect of the imidazolium moiety as well as the metal cation-π (pyrene) interactions. Furthermore, this homogeneous catalyst PIL was easily separated from the reaction mixture using reduced graphene oxide by π-π stacking with the pyrene of PIL.
Kerr-gated picosecond Raman spectroscopy and Raman photon migration of equine bone tissue with 400-nm excitation

NASA Astrophysics Data System (ADS)

Morris, Michael D.; Goodship, Allen E.; Draper, Edward R. C.; Matousek, Pavel; Towrie, Michael; Parker, Anthony W.

2004-07-01

We show that Raman spectroscopy with visible lasers, even in the deep blue is possible with time-gated Raman spectroscopy. A 4 picosec time gate allows efficient fluorescence rejection, up to 1000X, and provides almost background-free Raman spectra with low incident laser power. The technology enables spectroscopy with better than 10X higher scattering efficiency than is possible with the NIR (785 nm and 830 nm) lasers that are conventionally used. Raman photon migration is shown to allow depth penetration. We show for the first time that Kerr-gated Raman spectra of bone tissue with blue laser excitation enables both fluorescence rejection and depth penetration.

Novel Palm Fatty Acid Functionalized Magnetite Nanoparticles for Magnetic Solid-Phase Extraction of Trace Polycyclic Aromatic Hydrocarbons from Environmental Samples.

PubMed

Rozi, Siti Khalijah Mahmad; Nodeh, Hamid Rashidi; Kamboh, Muhammad Afzal; Manan, Ninie Suhana Abdul; Mohamad, Sharifah

2017-07-01

A novel adsorbent, palm fatty acid coated magnetic Fe 3 O 4 nanoparticles (MNP-FA) was successfully synthesized with immobilization of the palm fatty acid onto the surface of MNPs. The successful synthesis of MNP-FA was further confirmed by X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and Energy dispersive X-Ray spectroscopy (EDX) analyses and water contact angle (WCA) measurement. This newly synthesized MNP-FA was applied as magnetic solid phase extraction (MSPE) adsorbent for the enrichment of polycyclic aromatic hydrocarbons (PAHs), namely fluoranthene (FLT), pyrene (Pyr), chrysene (Cry) and benzo(a)pyrene (BaP) from environmental samples prior to High Performance Liquid Chromatography- Diode Array Detector (HPLC-DAD) analysis. The MSPE method was optimized by several parameters such as amount of sorbent, desorption solvent, volume of desorption solvent, extraction time, desorption time, pH and sample volume. Under the optimized conditions, MSPE method provided a low detection limit (LOD) for FLT, Pyr, Cry and BaP in the range of 0.01-0.05 ng mL -1 . The PAHs recoveries of the spiked leachate samples ranged from 98.5% to 113.8% with the RSDs (n = 5) ranging from 3.5% to 12.2%, while for the spiked sludge samples, the recoveries ranged from 81.1% to 119.3% with the RSDs (n = 5) ranging from 3.1% to 13.6%. The recyclability study revealed that MNP-FA has excellent reusability up to five times. Chromatrographic analysis demonstrated the suitability of MNP-FA as MSPE adsorbent for the efficient extraction of PAHs from environmental samples.
Effect of bioaugmentation to enhance phytoremediation for removal of phenanthrene and pyrene from soil with Sorghum and Onobrychis sativa

PubMed Central

2014-01-01

The use of plants to remove Poly-aromatic-hydrocarbons (PAHs) from soil (phytoremediation) is emerging as a cost-effective method. Phytoremediation of contaminated soils can be promoted by the use of adding microorganisms with the potential of pollution biodegradation (bioaugmentation). In the present work, the effect of bacterial consortium was studied on the capability of Sorghum and Onobrychis sativa for the phytoremediation of soils contaminated with phenanthrene and pyrene. 1.5 kg of the contaminated soil in the ratio of 100 and 300 mg phenanthrene and/or pyrene per kg of dry soil was then transferred into each pot (nine modes). The removal efficiency of natural, phytoremediation and bioaugmentation, separately and combined, were evaluated. The samples were kept under field conditions, and the remaining concentrations of pyrene and phenanthrene were determined after 120 days. The rhizosphere as well as the microbial population of the soil was also determined. Results indicated that both plants were able to significantly remove pyrene and phenanthrene from the contaminated soil samples. Phytoremediation alone had the removal efficiency of about 63% and 74.5% for pyrene and phenanthrene respectively. In the combined mode, the removal efficiency dramatically increased, leading to pyrene and phenanthrene removal efficiencies of 74.1% and 85.02% for Onobrychis sativa and 73.84% and 85.2% for sorghum, respectively. According to the results from the present work, it can be concluded that Onobrychis sativa and sorghum are both efficient in removing pyrene and phenanthrene from contamination and bioaugmentation can significantly enhance the phytoremediation of soils contaminated with pyrene and phenanthrene by 22% and 16% respectively. PMID:24406158
Effect of mixed soil microbiomes on pyrene removal and the response of the soil microorganisms.

PubMed

Wang, Beibei; Teng, Ying; Xu, Yongfeng; Chen, Wei; Ren, Wenjie; Li, Yan; Christie, Peter; Luo, Yongming

2018-05-28

Mixed soil microbiomes were established by introducing aliquots of a paddy soil into a red soil. The new mixed microbiomes effectively metabolized high-molecular-weight polycyclic aromatic hydrocarbons (PAHs, pyrene) in the soil mixtures. The pyrene removal efficiencies were 19% and 98%, respectively, in the original red soil and the paddy soil. The pyrene removal effectiveness by the mixed microbial community was enhanced by increasing the amount of paddy soil inoculant and the pyrene removal rates were 93%, 58% and 27% in paddy soil/red soil mixtures of 1:1, 3:7 and 1:9 (w/w), respectively. Supplementation with sterile paddy soil and nutrients changed the soil environment but the pyrene removal efficiency was not enhanced, indicating that the microbial composition largely determined the extent of pyrene removal. Moreover, the pyrene removal rate was positively related to the pyrene dioxygenase gene (nidA) abundance. The greater the percentage of the paddy soil in the soil mixture the greater the similarity of the mixed microbiome to that of the original paddy soil itself. The community of the inoculated sterile paddy soil was similar to that of the red soil and the community diverged from those of the red soil and the paddy soil with increasing culture time. After culture for 42 days, some enriched genera were responsible for PAH degradation, notably Nevskia, Ralstonia, Gemmatimonas and Lysobacter, while some genera have no clear classification information or category name at the genus level, such as f__Acidobacteriaceae and o__JG30-KF-AS9. This study is very important in recognizing the role of natural soil in the formation of a mixed microbiome to stimulate the degradation of PAHs in a soil with low intrinsic PAH degradation capability. Copyright © 2018 Elsevier B.V. All rights reserved.
Spatial fluorescence cross-correlation spectroscopy between core and ring pinholes

NASA Astrophysics Data System (ADS)

Blancquaert, Yoann; Delon, Antoine; Derouard, Jacques; Jaffiol, Rodolphe

2006-04-01

Fluorescence Correlation Spectroscopy (FCS) is an attractive method to measure molecular concentration, mobility parameters and chemical kinetics. However its ability to descriminate different diffusing species needs to be improved. Recently, we have proposed a simplified spatial Fluorescence cross Correlation Spectroscopy (sFCCS) method, allowing, with only one focused laser beam to obtain two confocal volumes spatially shifted. Now, we present a new sFCCS optical geometry where the two pinholes, a ring and core, are encapsulated one in the other. In this approach all physical and chemical processes that occur in a single volume, like singlet-triplet dynamics and photobleaching, can be eliminated; moreover, this new optical geometry optimises the collection of fluorescence. The first cross Correlation curves for Rhodamine 6G (Rh6G) in Ethanol are presented, in addition to the effect of the size of fluorescent particules (nano-beads, diameters : 20, 100 and 200 nm). The relative simplicity of the method leads us to propose sFCCS as an appropriate method for the determination of diffusion parameters of fluorophores in solution or cells. Nevertheless, progresses in the ingeniering of the optical Molecular Detection Efficiency volumes are highly desirable, in order to improve the descrimination between the cross correlated volumes.
Increasing selectivity for TNT-based explosive detection by synchronous luminescence and derivative spectroscopy with quantum yields of selected aromatic amines.

PubMed

Sheaff, Chrystal N; Eastwood, Delyle; Wai, Chien M

2007-01-01

The detection of explosive material is at the forefront of current analytical problems. A detection method is desired that is not restricted to detecting only explosive materials, but is also capable of identifying the origin and type of explosive. It is essential that a detection method have the selectivity to distinguish among compounds in a mixture of explosives. The nitro compounds found in explosives have low fluorescent yields or are considered to be non-fluorescent; however, after reduction, the amino compounds exhibit relatively high fluorescence. We discuss how to increase selectivity of explosive detection using fluorescence; this includes synchronous luminescence and derivative spectroscopy with appropriate smoothing. By implementing synchronous luminescence and derivative spectroscopy, we were able to resolve the reduction products of one major TNT-based explosive compound, 2,4-diaminotoluene, and the reduction products of other minor TNT-based explosives in a mixture. We also report for the first time the quantum yields of these important compounds. Relative quantum yields are useful in establishing relative fluorescence intensities and are an important spectroscopic measurement of molecules. Our approach allows for rapid, sensitive, and selective detection with the discrimination necessary to distinguish among various explosives.
Characterization of brightness and stoichiometry of bright particles by flow-fluorescence fluctuation spectroscopy.

PubMed

Johnson, Jolene; Chen, Yan; Mueller, Joachim D

2010-11-03

Characterization of bright particles at low concentrations by fluorescence fluctuation spectroscopy (FFS) is challenging, because the event rate of particle detection is low and fluorescence background contributes significantly to the measured signal. It is straightforward to increase the event rate by flow, but the high background continues to be problematic for fluorescence correlation spectroscopy. Here, we characterize the use of photon-counting histogram analysis in the presence of flow. We demonstrate that a photon-counting histogram efficiently separates the particle signal from the background and faithfully determines the brightness and concentration of particles independent of flow speed, as long as undersampling is avoided. Brightness provides a measure of the number of fluorescently labeled proteins within a complex and has been used to determine stoichiometry of protein complexes in vivo and in vitro. We apply flow-FFS to determine the stoichiometry of the group specific antigen protein within viral-like particles of the human immunodeficiency virus type-1 from the brightness. Our results demonstrate that flow-FFS is a sensitive method for the characterization of complex macromolecular particles at low concentrations. Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Affinity capillary electrophoresis and fluorescence spectroscopy for studying enantioselective interactions between omeprazole enantiomer and human serum albumin.

PubMed

Xu, Yujing; Hong, Tingting; Chen, Xueping; Ji, Yibing

2017-05-01

Baseline separation of omeprazole (OME) enantiomers was achieved by affinity capillary electrophoresis (ACE), using human serum albumin (HSA) as the chiral selector. The influence of several experimental variables such as HSA concentration, the type and content of organic modifiers, applied voltage and running buffer concentration on the separation was evaluated. The binding of esomeprazole (S-omeprazole, S-OME) and its R-enantiomer (R-omeprazole, R-OME) to HSA under simulated physiological conditions was studied by ACE and fluorescence spectroscopy which was considered as a reference method. ACE studies demonstrated that the binding constants of the two enantiomers and HSA were 3.18 × 10 3 M -1 and 5.36 × 10 3 M -1 , respectively. The binding properties including the fluorescence quenching mechanisms, binding constants, binding sites and the number of binding sites were obtained by fluorescence spectroscopy. Though the ACE method could not get enough data when compared with the fluorescence spectrum method, the separation and binding studies of chiral drugs could be achieved simultaneously via this method. This study is of great significance for the investigation and clinical application of chiral drugs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Fluorescence-based microendoscopes for breast cancer ductoscopy

NASA Astrophysics Data System (ADS)

Zeylikovich, Iosif; Tang, Guichen C.; Katz, A.; Budansky, Yury; Alfano, R. R.

2006-02-01

Recently microendoscopes are being developed as a tool to detection cancer or pre-cancerous lesions in the milk ducts of the human breast. The microendoscope can be inserted into the duct through the nipple. Integration of fluorescence spectroscopy into microendoscopy can provide an improved platform for real-time cancer detection followed by immediate intervention. Typically, the optical fibers employed by existing microendoscope systems transmit in the 450 to 900 nm range. A prototype system combining fluorescence spectroscopy with visible imaging by microendoscopy is described and preliminary measurements on ex vivo human breast tissues are presented. Image resolution and distortion are discussed.
Ultrafast dynamics of photoactive yellow protein via the photoexcitation and emission processes.

PubMed

Nakamura, Ryosuke; Hamada, Norio; Ichida, Hideki; Tokunaga, Fumio; Kanematsu, Yasuo

2007-01-01

Pump-dump fluorescence spectroscopy was performed for photoactive yellow protein (PYP) at room temperature. The effect of the dump pulse on the population of the potential energy surface of the electronic excited state was examined as depletion in the stationary fluorescence intensity. The dynamic behavior of the population in the electronic excited state was successfully probed in the various combinations of the pump-dump delay, the dump-pulse wavelength, the dump-pulse energy and the observation wavelength. The experimental results were compared with the results obtained by the femtosecond time-resolved fluorescence spectroscopy.
Integrated fluorescence correlation spectroscopy device for point-of-care clinical applications

PubMed Central

Olson, Eben; Torres, Richard; Levene, Michael J.

2013-01-01

We describe an optical system which reduces the cost and complexity of fluorescence correlation spectroscopy (FCS), intended to increase the suitability of the technique for clinical use. Integration of the focusing optics and sample chamber into a plastic component produces a design which is simple to align and operate. We validate the system by measurements on fluorescent dye, and compare the results to a commercial instrument. In addition, we demonstrate its application to measurements of concentration and multimerization of the clinically relevant protein von Willebrand factor (vWF) in human plasma. PMID:23847733
Rate constant for the reaction NH2 + NO from 216 to 480 K

NASA Technical Reports Server (NTRS)

Stief, L. J.; Brobst, W. D.; Nava, D. F.; Borkowski, R. P.; Michael, J. V.

1982-01-01

The absolute rate constant was measured by the technique of flash photolysis-laser induced fluorescence (FP-LIF). NH2 radicals were produced by the flash photolysis of ammonia and the fluorescent NH2 photons were measured by multiscaling techniques. At each temperature, the results were independent of variations in total pressure, and flash intensity. The results are compared with previous determinations using the techniques of mass spectrometry, absorption spectroscopy, laser absorption spectroscopy, and laser induced fluorescence. The implications of the results are discussed with regard to combustion, post combustion, and atmospheric chemistry. The results are also discussed theoretically.
UV-Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 2: selected applications.

PubMed

Antosiewicz, Jan M; Shugar, David

In Part 2 we discuss application of several different types of UV-Vis spectroscopy, such as normal, difference, and second-derivative UV absorption spectroscopy, fluorescence spectroscopy, linear and circular dichroism spectroscopy, and Raman spectroscopy, of the side-chain of tyrosine residues in different molecular environments. We review the ways these spectroscopies can be used to probe complex protein structures.
UV-Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 2: selected applications.

PubMed

Antosiewicz, Jan M; Shugar, David

2016-06-01

In Part 2 we discuss application of several different types of UV-Vis spectroscopy, such as normal, difference, and second-derivative UV absorption spectroscopy, fluorescence spectroscopy, linear and circular dichroism spectroscopy, and Raman spectroscopy, of the side-chain of tyrosine residues in different molecular environments. We review the ways these spectroscopies can be used to probe complex protein structures.
Characterizing chlorine oxidation of dissolved organic matter and disinfection by-product formation with fluorescence spectroscopy and parallel factor analysis

NASA Astrophysics Data System (ADS)

Beggs, Katherine M. H.; Summers, R. Scott; McKnight, Diane M.

2009-12-01

Relationships between chlorine demand and disinfection by-product (DBP) formation during chlorination and fluorescence of dissolved organic matter (DOM) were developed. Fluorescence excitation and emission (EEM) spectroscopy was employed, and parameters including fluorescence index, redox index, and overall fluorescence intensity (OFI) were correlated to chlorine demand and DBP formation. The EEMs were also analyzed using a well established global parallel factor analysis (PARAFAC) model which resolves the fluorescence signal into 13 components, including quinone-like and protein-like components. Over an 8-day chlorination period the OFI and sum of the 13 PARAFAC loadings decreased by more than 70%. The remaining identified quinone-like compounds within the DOM were shifted to a more oxidized state. Quinone fluorescence was strongly correlated to both reduced fluorescence intensity and to chlorine demand which indicates that fluorescence may be used to track the chlorine oxidation of DOM. Quinone fluorescence was also correlated strongly with both classes of regulated DBPs: total trihalomethanes and haloacetic acids. Quinone-like components were found to be strongly correlated to overall, short-term, and long-term specific DBP formation. The results of this study show that fluorescence is a useful tool in tracking both DOM oxidation and DBP formation during chlorination.
Facile green synthesis of fluorescent N-doped carbon dots from Actinidia deliciosa and their catalytic activity and cytotoxicity applications

NASA Astrophysics Data System (ADS)

Arul, Velusamy; Sethuraman, Mathur Gopalakrishnan

2018-04-01

Green synthesis of fluorescent nitrogen doped carbon dots (N-CDs) using Actinidia deliciosa (A. deliciosa) fruit extract as a carbon precursor and aqueous ammonia as a nitrogen dopant is reported here. The synthesized N-CDs were characterized by high resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), selected area electron diffraction (SAED), UV-Visible spectroscopy (UV-Vis), fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The average size of the N-CDs was approximately 3.59 nm and the calculated inter layer distance was found to be 0.21 nm. Raman spectroscopy and SAED pattern revealed the graphitic nature of the synthesized N-CDs. The N-CDs were found to emit intense blue color at 405 nm under the excitation of 315 nm. The doping of nitrogen over the surface of the N-CDs was confirmed by EDS, FT-IR and XPS studies. The synthesized N-CDs were found to exhibit excellent catalytic activity in the reduction of Rhodamine-B using sodium borohydrate. The MTT assay was used to evaluate the cytotoxicity and biocompatibility of N-CDs towards L-929 and MCF-7 cells. From the results obtained, it was found that the N-CDs exhibit low cytotoxicity and superior biocompatibility on both L-929 and MCF-7 cells.
Study on the conformation changes of Lysozyme induced by Hypocrellin A: The mechanism investigation

NASA Astrophysics Data System (ADS)

Ma, Fei; Huang, He-Yong; Zhou, Lin; Yang, Chao; Zhou, Jia-Hong; Liu, Zheng-Ming

2012-11-01

The interactions between Lysozyme and Hypocrellin A are investigated in details using time-resolved fluorescence, fourier transform infrared spectroscopy (FTIR), circular dichroism spectroscopy (CD), three-dimensional fluorescence spectra, and thermal gravimetric analysis (TGA) techniques. The results of time-resolved fluorescence suggest that the quenching mechanism is static quenching. FTIR and CD spectroscopy provide evidences of the reducing of α-helix after interaction. Hypocrellin A could change the micro-environmental of Lysozyme according to hydrophobic interaction between the aromatic ring and the hydrophobic amino acid residues, and the altered polypeptide backbone structures induce the reduction of α-helical structures. Moreover, TGA study further demonstrates the structure changes of Lysozyme on the effect of Hypocrellin A. This study could provide some important information for the derivatives of HA in pharmacy, pharmacology and biochemistry.
Decorating multi-walled carbon nanotubes with quantum dots for construction of multi-color fluorescent nanoprobes.

PubMed

Jia, Nengqin; Lian, Qiong; Tian, Zhong; Duan, Xin; Yin, Min; Jing, Lihong; Chen, Shouhui; Shen, Hebai; Gao, Mingyuan

2010-01-29

Novel multi-color fluorescent nanoprobes were prepared by electrostatically assembling differently sized CdTe quantum dots on polyethylenimine (PEI) functionalized multi-walled carbon nanotubes (MWNTs). The structural and optical properties of the nano-assemblies (MWNTs-PEI-CdTe) were characterized by transmission electron microscopy (TEM), electron diffraction spectra (EDS), Raman spectroscopy, confocal microscopy and photoluminescence spectroscopy (PL), respectively. Electrochemical impedance spectroscopy (EIS) was also applied to investigate the electrostatic assembling among oxidized MWNTs, PEI and CdTe. Furthermore, confocal fluorescence microscopy was used to monitor the nano-assemblies' delivery into tumor cells. It was found that the nano-assemblies exhibit efficient intracellular transporting and strong intracellular tracking. These properties would make this luminescent nano-assembly an excellent building block for the construction of intracellular nanoprobes, which could hold great promise for biomedical applications.
Enhancing the sensitivity of fluorescence correlation spectroscopy by using time-correlated single photon counting.

PubMed

Lamb, D C; Müller, B K; Bräuchle, C

2005-10-01

Fluorescence correlation spectroscopy (FCS) and fluorescence cross-correlation spectroscopy (FCCS) are methods that extract information about a sample from the influence of thermodynamic equilibrium fluctuations on the fluorescence intensity. This method allows dynamic information to be obtained from steady state equilibrium measurements and its popularity has dramatically increased in the last 10 years due to the development of high sensitivity detectors and its combination with confocal microscopy. Using time-correlated single-photon counting (TCSPC) detection and pulsed excitation, information over the duration of the excited state can be extracted and incorporated in the analysis. In this short review, we discuss new methodologies that have recently emerged which incorporated fluorescence lifetime information or TCSPC data in the FCS and FCCS analysis. Time-gated FCS discriminates between which photons are to be incorporated in the analysis dependent upon their arrival time after excitation. This allows for accurate FCS measurements in the presence of fluorescent background, determination of sample homogeneity, and the ability to distinguish between static and dynamic heterogeneities. A similar method, time-resolved FCS can be used to resolve the individual correlation functions from multiple fluorophores through the different fluorescence lifetimes. Pulsed interleaved excitation (PIE) encodes the excitation source into the TCSPC data. PIE can be used to perform dual-channel FCCS with a single detector and allows elimination of spectral cross-talk with dual-channel detection. For samples that undergo fluorescence resonance energy transfer (FRET), quantitative FCCS measurements can be performed in spite of the FRET and the static FRET efficiency can be determined.
IRIS Toxicological Review of Benzo[a]pyrene (External Review Draft)

EPA Science Inventory

The IRIS Toxicological Review of Benzo[a]pyrene was released for external peer review in September 2014. The EPA’s Science Advisory Board’s (SAB) Chemical Assessment Advisory Committee (CAAC) conducted a peer review of the scientific basis supporting the benzo[a]pyrene assessmen...
Diurnal Variability in Chlorophyll-a, Carotenoids, CDOM and SO42− Intensity of Offshore Seawater Detected by an Underwater Fluorescence-Raman Spectral System

PubMed Central

Chen, Jing; Ye, Wangquan; Guo, Jinjia; Luo, Zhao; Li, Ying

2016-01-01

A newly developed integrated fluorescence-Raman spectral system (λex = 532 nm) for detecting Chlorophyll-a (chl-a), Chromophoric Dissolved Organic Matter (CDOM), carotenoids and SO42− in situ was used to successfully investigate the diurnal variability of all above. Simultaneously using the integration of fluorescence spectroscopy and Raman spectroscopy techniques provided comprehensive marine information due to the complementarity between the different excitation mechanisms and different selection rules. The investigation took place in offshore seawater of the Yellow Sea (36°05′40′′ N, 120°31′32′′ E) in October 2014. To detect chl-a, CDOM, carotenoids and SO42−, the fluorescence-Raman spectral system was deployed. It was found that troughs of chl-a and CDOM fluorescence signal intensity were observed during high tides, while the signal intensity showed high values with larger fluctuations during ebb-tide. Chl-a and carotenoids were influenced by solar radiation within a day cycle by different detection techniques, as well as displaying similar and synchronous tendency. CDOM fluorescence cause interference to the measurement of SO42−. To avoid such interference, the backup Raman spectroscopy system with λex = 785 nm was employed to detect SO42− concentration on the following day. The results demonstrated that the fluorescence-Raman spectral system has great potential in detection of chl-a, carotenoids, CDOM and SO42− in the ocean. PMID:27420071

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Sample records for pyrene fluorescence spectroscopy

Abstract