Poly(o-phenylenediamine) colloid-quenched fluorescent oligonucleotide as a probe for fluorescence-enhanced nucleic acid detection.

PubMed

Tian, Jingqi; Li, Hailong; Luo, Yonglan; Wang, Lei; Zhang, Yingwei; Sun, Xuping

2011-02-01

In this Letter, we demonstrate that chemical oxidation polymerization of o-phenylenediamine (OPD) by potassium bichromate at room temperature results in the formation of submicrometer-scale poly(o-phenylenediamine) (POPD) colloids. Such colloids can absorb and quench dye-labeled single-stranded DNA (ssDNA) very effectively. In the presence of a target, a hybridization event occurs, which produces a double-stranded DNA (dsDNA) that detaches from the POPD surface, leading to recovery of dye fluorescence. With the use of an oligonucleotide (OND) sequence associated with human immunodeficiency virus (HIV) as a model system, we demonstrate the proof of concept that POPD colloid-quenched fluorescent OND can be used as a probe for fluorescence-enhanced nucleic acid detection with selectivity down to single-base mismatch.

The Arabidopsis thaliana REDUCED EPIDERMAL FLUORESCENCE1 gene encodes an aldehyde dehydrogenase involved in ferulic acid and sinapic acid biosynthesis.

PubMed

Nair, Ramesh B; Bastress, Kristen L; Ruegger, Max O; Denault, Jeff W; Chapple, Clint

2004-02-01

Recent research has significantly advanced our understanding of the phenylpropanoid pathway but has left in doubt the pathway by which sinapic acid is synthesized in plants. The reduced epidermal fluorescence1 (ref1) mutant of Arabidopsis thaliana accumulates only 10 to 30% of the sinapate esters found in wild-type plants. Positional cloning of the REF1 gene revealed that it encodes an aldehyde dehydrogenase, a member of a large class of NADP(+)-dependent enzymes that catalyze the oxidation of aldehydes to their corresponding carboxylic acids. Consistent with this finding, extracts of ref1 leaves exhibit low sinapaldehyde dehydrogenase activity. These data indicate that REF1 encodes a sinapaldehyde dehydrogenase required for sinapic acid and sinapate ester biosynthesis. When expressed in Escherichia coli, REF1 was found to exhibit both sinapaldehyde and coniferaldehyde dehydrogenase activity, and further phenotypic analysis of ref1 mutant plants showed that they contain less cell wall-esterified ferulic acid. These findings suggest that both ferulic acid and sinapic acid are derived, at least in part, through oxidation of coniferaldehyde and sinapaldehyde. This route is directly opposite to the traditional representation of phenylpropanoid metabolism in which hydroxycinnamic acids are instead precursors of their corresponding aldehydes.

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.

Fluorescence energy transfer as a probe for nucleic acid structures and sequences.

PubMed Central

Mergny, J L; Boutorine, A S; Garestier, T; Belloc, F; Rougée, M; Bulychev, N V; Koshkin, A A; Bourson, J; Lebedev, A V; Valeur, B

1994-01-01

The primary or secondary structure of single-stranded nucleic acids has been investigated with fluorescent oligonucleotides, i.e., oligonucleotides covalently linked to a fluorescent dye. Five different chromophores were used: 2-methoxy-6-chloro-9-amino-acridine, coumarin 500, fluorescein, rhodamine and ethidium. The chemical synthesis of derivatized oligonucleotides is described. Hybridization of two fluorescent oligonucleotides to adjacent nucleic acid sequences led to fluorescence excitation energy transfer between the donor and the acceptor dyes. This phenomenon was used to probe primary and secondary structures of DNA fragments and the orientation of oligodeoxynucleotides synthesized with the alpha-anomers of nucleoside units. Fluorescence energy transfer can be used to reveal the formation of hairpin structures and the translocation of genes between two chromosomes. PMID:8152922

New Fluorescent Nanoparticles for Ultrasensitive Detection of Nucleic Acids by Optical Methods.

PubMed

Westergaard Mulberg, Mads; Taskova, Maria; Thomsen, Rasmus P; Okholm, Anders H; Kjems, Jørgen; Astakhova, Kira

2017-08-17

For decades the detection of nucleic acids and their interactions at low abundances has been a challenging task that has thus far been solved by enzymatic target amplification. In this work we aimed at developing efficient tools for amplification-free nucleic acid detection, which resulted in the synthesis of new fluorescent nanoparticles. Here, the fluorescent nanoparticles were made by simple and inexpensive radical emulsion polymerization of butyl acrylate in the presence of fluorescent dyes and additional functionalization reagents. This provided ultra-bright macrofluorophores of 9-84 nm mean diameter, modified with additional alkyne and amino groups for bioconjugation. By using click and NHS chemistries, the new nanoparticles were attached to target-specific DNA probes that were used in fluorimetry and fluorescence microscopy. Overall, these fluorescent nanoparticles and their oligonucleotide derivatives have higher photostability, brighter fluorescence and hence dramatically lower limits of target detection than the individual organic dyes. These properties make them useful in approaches directed towards ultrasensitive detection of nucleic acids, in particular for imaging and in vitro diagnostics of DNA. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fluorescence properties of Schiff base - N,N‧-bis(salicylidene) - 1,2-Phenylenediamine in presence of bile acid host

NASA Astrophysics Data System (ADS)

Roy, Nayan; Paul, Pradip C.; Singh, T. Sanjoy

2015-05-01

Fluorescence properties of Schiff base - N,N‧-bis(salicylidene) - 1,2-phenylenediamine (LH2) is used to study the micelles formed by aggregation of different important bile acids like cholic acid, deoxycholic acid, chenodeoxycholic acid and glycocholic acid by steady state and picosecond time-resolved fluorescence spectroscopy. The fluorescence band intensity was found out to increase with concomitant red shift with gradual addition of different bile acids. Binding constant of the probe with different bile acids as well as critical micelle concentration was obtained from the variation of fluorescence intensity on increasing concentration of bile acids in the medium. The increase in fluorescence quantum yields, fluorescence decay times and substantial decrease in nonradiative decay rate constants in bile acids micellar environment points to the restricted motion of the fluorophore inside the micellar subdomains.

Recent Advances in Fluorescent Arylboronic Acids for Glucose Sensing

PubMed Central

Hansen, Jon Stefan; Christensen, Jørn Bolstad

2013-01-01

Continuous glucose monitoring (CGM) is crucial in order to avoid complications caused by change in blood glucose for patients suffering from diabetes mellitus. The long-term consequences of high blood glucose levels include damage to the heart, eyes, kidneys, nerves and other organs, among others, caused by malign glycation of vital protein structures. Fluorescent monitors based on arylboronic acids are promising candidates for optical CGM, since arylboronic acids are capable of forming arylboronate esters with 1,2-cis-diols or 1,3-diols fast and reversibly, even in aqueous solution. These properties enable arylboronic acid dyes to provide immediate information of glucose concentrations. Thus, the replacement of the commonly applied semi-invasive and non-invasive techniques relying on glucose binding proteins, such as concanavalin A, or enzymes, such as glucose oxidase, glucose dehydrogenase and hexokinases/glucokinases, might be possible. The recent progress in the development of fluorescent arylboronic acid dyes will be emphasized in this review. PMID:25586415

The Arabidopsis thaliana REDUCED EPIDERMAL FLUORESCENCE1 Gene Encodes an Aldehyde Dehydrogenase Involved in Ferulic Acid and Sinapic Acid Biosynthesis

PubMed Central

Nair, Ramesh B.; Bastress, Kristen L.; Ruegger, Max O.; Denault, Jeff W.; Chapple, Clint

2004-01-01

Recent research has significantly advanced our understanding of the phenylpropanoid pathway but has left in doubt the pathway by which sinapic acid is synthesized in plants. The reduced epidermal fluorescence1 (ref1) mutant of Arabidopsis thaliana accumulates only 10 to 30% of the sinapate esters found in wild-type plants. Positional cloning of the REF1 gene revealed that it encodes an aldehyde dehydrogenase, a member of a large class of NADP+-dependent enzymes that catalyze the oxidation of aldehydes to their corresponding carboxylic acids. Consistent with this finding, extracts of ref1 leaves exhibit low sinapaldehyde dehydrogenase activity. These data indicate that REF1 encodes a sinapaldehyde dehydrogenase required for sinapic acid and sinapate ester biosynthesis. When expressed in Escherichia coli, REF1 was found to exhibit both sinapaldehyde and coniferaldehyde dehydrogenase activity, and further phenotypic analysis of ref1 mutant plants showed that they contain less cell wall–esterified ferulic acid. These findings suggest that both ferulic acid and sinapic acid are derived, at least in part, through oxidation of coniferaldehyde and sinapaldehyde. This route is directly opposite to the traditional representation of phenylpropanoid metabolism in which hydroxycinnamic acids are instead precursors of their corresponding aldehydes. PMID:14729911

Selection of fluorophore and quencher pairs for fluorescent nucleic acid hybridization probes.

PubMed

Marras, Salvatore A E

2006-01-01

With the introduction of simple and relatively inexpensive methods for labeling nucleic acids with nonradioactive labels, doors have been opened that enable nucleic acid hybridization probes to be used for research and development, as well as for clinical diagnostic applications. The use of fluorescent hybridization probes that generate a fluorescence signal only when they bind to their target enables real-time monitoring of nucleic acid amplification assays. The use of hybridization probes that bind to the amplification products in real-time markedly improves the ability to obtain quantitative results. Furthermore, real-time nucleic acid amplification assays can be carried out in sealed tubes, eliminating carryover contamination. Because fluorescent hybridization probes are available in a wide range of colors, multiple hybridization probes, each designed for the detection of a different nucleic acid sequence and each labeled with a differently colored fluorophore, can be added to the same nucleic acid amplification reaction, enabling the development of high-throughput multiplex assays. It is therefore important to carefully select the labels of hybridization probes, based on the type of hybridization probe used in the assay, the number of targets to be detected, and the type of apparatus available to perform the assay. This chapter outlines different aspects of choosing appropriate labels for the different types of fluorescent hybridization probes used with different types of spectrofluorometric thermal cyclers.

Size-Selective Detection of Picric Acid by Fluorescent Palladium Macrocycles.

PubMed

Kumar, Sushil; Kishan, Ram; Kumar, Pramod; Pachisia, Sanya; Gupta, Rajeev

2018-02-19

This work presents the synthesis and characterization of two palladium-based fluorescent macrocycles offering hydrogen-bonding cavities of contrasting dimensions. Both palladium macrocycles function as chemosensors for the detection of nitroaromatics, whereas the larger macrocycle not only illustrates nanomolar detection of picric acid but also transports its significant amount from an aqueous to an organic phase.

Fluorescent hybridization probes for nucleic acid detection.

PubMed

Guo, Jia; Ju, Jingyue; Turro, Nicholas J

2012-04-01

Due to their high sensitivity and selectivity, minimum interference with living biological systems, and ease of design and synthesis, fluorescent hybridization probes have been widely used to detect nucleic acids both in vivo and in vitro. Molecular beacons (MBs) and binary probes (BPs) are two very important hybridization probes that are designed based on well-established photophysical principles. These probes have shown particular applicability in a variety of studies, such as mRNA tracking, single nucleotide polymorphism (SNP) detection, polymerase chain reaction (PCR) monitoring, and microorganism identification. Molecular beacons are hairpin oligonucleotide probes that present distinctive fluorescent signatures in the presence and absence of their target. Binary probes consist of two fluorescently labeled oligonucleotide strands that can hybridize to adjacent regions of their target and generate distinctive fluorescence signals. These probes have been extensively studied and modified for different applications by modulating their structures or using various combinations of fluorophores, excimer-forming molecules, and metal complexes. This review describes the applicability and advantages of various hybridization probes that utilize novel and creative design to enhance their target detection sensitivity and specificity.

Comparative Study of the Fatty Acid Binding Process of a New FABP from Cherax quadricarinatus by Fluorescence Intensity, Lifetime and Anisotropy

PubMed Central

Li, Jiayao; Henry, Etienne; Wang, Lanmei; Delelis, Olivier; Wang, Huan; Simon, Françoise; Tauc, Patrick; Brochon, Jean-Claude; Zhao, Yunlong; Deprez, Eric

2012-01-01

Fatty acid-binding proteins (FABPs) are small cytosolic proteins, largely distributed in invertebrates and vertebrates, which accomplish uptake and intracellular transport of hydrophobic ligands such as fatty acids. Although long chain fatty acids play multiple crucial roles in cellular functions (structural, energy metabolism, regulation of gene expression), the precise functions of FABPs, especially those of invertebrate species, remain elusive. Here, we have identified and characterized a novel FABP family member, Cq-FABP, from the hepatopancreas of red claw crayfish Cherax quadricarinatus. We report the characterization of fatty acid-binding affinity of Cq-FABP by four different competitive fluorescence-based assays. In the two first approaches, the fluorescent probe 8-Anilino-1-naphthalenesulfonate (ANS), a binder of internal cavities of protein, was used either by directly monitoring its fluorescence emission or by monitoring the fluorescence resonance energy transfer occurring between the single tryptophan residue of Cq-FABP and ANS. The third and the fourth approaches were based on the measurement of the fluorescence emission intensity of the naturally fluorescent cis-parinaric acid probe or the steady-state fluorescence anisotropy measurements of a fluorescently labeled fatty acid (BODIPY-C16), respectively. The four methodologies displayed consistent equilibrium constants for a given fatty acid but were not equivalent in terms of analysis. Indeed, the two first methods were complicated by the existence of non specific binding modes of ANS while BODIPY-C16 and cis-parinaric acid specifically targeted the fatty acid binding site. We found a relationship between the affinity and the length of the carbon chain, with the highest affinity obtained for the shortest fatty acid, suggesting that steric effects primarily influence the interaction of fatty acids in the binding cavity of Cq-FABP. Moreover, our results show that the binding affinities of several fatty

Three-dimensional fluorescence analysis of chernozem humic acids and their electrophoretic fractions

NASA Astrophysics Data System (ADS)

Trubetskoi, O. A.; Trubetskaya, O. E.

2017-09-01

Polyacrylamide gel electrophoresis in combination with size-exclusion chromatography (SEC-PAGE) has been used to obtain stable electrophoretic fractions of different molecular size (MS) from chernozem humic acids (HAs). Three-dimensional fluorescence charts of chernozem HAs and their fractions have been obtained for the first time, and all fluorescence excitation-emission maxima have been identified in the excitation wavelength range of 250-500 nm. It has been found that fractionation by the SEC-PAGE method results in a nonuniform distribution of protein- and humin-like fluorescence of the original HA preparation among the electrophoretic fractions. The electrophoretic fractions of the highest and medium MSs have only the main protein-like fluorescence maximum and traces of humin-like fluorescence. In the electrophoretic fraction of the lowest MS, the intensity of protein-like fluorescence is low, but the major part of humin-like fluorescence is localized there. Relationships between the intensity of protein-like fluorescence and the weight distribution of amino acids have been revealed, as well as between the degree of aromaticity and the intensity of humin-like fluorescence in electrophoretic fractions of different MSs. The obtained relationships can be useful in the interpretation of the spatial structural organization and ecological functions of soil HAs.

Synchronous fluorescence determination of ferulic acid with Ce(IV) and sodium tripolyphosphate.

PubMed

Meng, F; Liu, P; Huang, F; Wang, L; Wu, X; Shen, L

2014-05-01

In this study, a synchronous fluorescence detection method for ferulic acid (FA) is proposed based on a redox reaction between FA and Ce(IV) sulfate in dilute sulfuric acid medium at room temperature. It was found that FA could reduce Ce(IV) to Ce(III) in acidic medium, and sodium tripolyphosphate could further enhance the intrinsic fluorescence of the Ce(III) produced. The enhanced extent of synchronous fluorescence intensity was in proportion to the concentration of FA over the range 3.0 × 10(-8) to 1.0 × 10(-5) mol/L. The corresponding limit of determination (S/N = 3) was 1.3 × 10(-8) mol/L. The proposed method was applied to the determination of sodium ferulate for injection sample with satisfactory results. Copyright © 2013 John Wiley & Sons, Ltd.

Interaction of cinnamic acid derivatives with serum albumins: A fluorescence spectroscopic study

NASA Astrophysics Data System (ADS)

Singh, T. Sanjoy; Mitra, Sivaprasad

2011-03-01

Cinnamic acid (CA) derivatives are known to possess broad therapeutic applications including anti-tumor activity. The present study was designed to determine the underlying mechanism and thermodynamic parameters for the binding of two CA based intramolecular charge transfer (ICT) fluorescent probes, namely, 4-(dimethylamino) cinnamic acid (DMACA) and trans-ethyl p-(dimethylamino) cinnamate (EDAC), with albumins by fluorescence spectroscopy. Stern-Volmer analysis of the tryptophan fluorescence quenching data in presence of the added ligand reveals fluorescence quenching constant ( κq), Stern-Volmer constant ( KSV) and also the ligand-protein association constant ( Ka). The thermodynamic parameters like enthalpy (Δ H) and entropy (Δ S) change corresponding to the ligand binding process were also estimated. The results show that the ligands bind into the sub-domain IIA of the proteins in 1:1 stoichiometry with an apparent binding constant value in the range of 10 4 dm 3 mol -1. In both the cases, the spontaneous ligand binding to the proteins occur through entropy driven mechanism, although the interaction of DMACA is relatively stronger in comparison with EDAC. The temperature dependence of the binding constant indicates the induced change in protein secondary structure.

A new boronic acid fluorescent sensor based on fluorene for monosaccharides at physiological pH

NASA Astrophysics Data System (ADS)

Hosseinzadeh, Rahman; Mohadjerani, Maryam; Pooryousef, Mona; Eslami, Abbas; Emami, Saeed

2015-06-01

Fluorescent boronic acids are very useful fluorescent sensor for detection of biologically important saccharides. Herein we synthesized a new fluorene-based fluorescent boronic acid that shows significant fluorescence changes upon addition of saccharides at physiological pH. Upon addition of fructose, sorbitol, glucose, galactose, ribose, and maltose at different concentration to the solution of 7-(dimethylamino)-9,9-dimethyl-9H-fluoren-2-yl-2-boronic acid (7-DMAFBA, 1), significant decreases in fluorescent intensity were observed. It was found that this boronic acid has high affinity (Ka = 3582.88 M-1) and selectivity for fructose over glucose at pH = 7.4. The sensor 1 showed a linear response toward D-fructose in the concentrations ranging from 2.5 × 10-5 to 4 × 10-4 mol L-1 with the detection limit of 1.3 × 10-5 mol L-1.

Fluorescence measurements of activity associated with a molecularly imprinted polymer imprinted to dipicolinic acid

NASA Astrophysics Data System (ADS)

Anderson, John; Pestov, Dmitry; Fischer, Robert L.; Webb, Stanley; Tepper, Gary C.

2004-03-01

Steady state and lifetime fluorescence measurements were acquired to measure the binding activity associated with molecularly imprinted polymer (MIP) microparticles imprinted to dipicolinic acid. Dipicolinic acid is a unique compound associated with the sporulation phase of spore-forming bacteria (e.g., genus Bacillus and Clostridium). Vinylic monomers were polymerized in a dimethylformamide solution containing the dipicolinic acid as a template. The resulting MIP was then pulverized and size selected into small microscale particles. Samplers were adapted incorporating the MIP particles within a dialyzer (500 MW). Tests were run on replicate samples of biologically active cultures representing both stationary phase and sporulation post fermentation products in standard media. The permeability of the membrane permitted diffusion of lighter molecular weight constituents from media effluents to enter the dialyzer chamber and contact the MIP. Extractions of the media were measured using steady state and lifetime fluorescence. Results showed dramatic steady state fluorescence changes as a function of excitation, emission and intensity and an estimated lifetime of 5.8 ns.

Enhancing fluorescence intensity of Ellagic acid in Borax-HCl-CTAB micelles

NASA Astrophysics Data System (ADS)

Wang, Feng; Huang, Wei; Zhang, Shuai; Liu, Guokui; Li, Kexiang; Tang, Bo

2011-03-01

Ellagic acid (C 14H 6O 8), a naturally occurring phytochemical, found mainly in berries and some nuts, has anticarcinogenic and antioxidant properties. It is found that fluorescence of Ellagic acid (EA) is greatly enhanced by micelle of cetyltrimethylammonium bromide (CTAB) surfactant. Based on this effect, a sensitive proposed fluorimetric method was applied for the determination of Ellagic acid in aqueous solution. In the Borax-HCl buffer, the fluorescence intensity of Ellagic acid in the presence of CTAB is proportional to the concentration of Ellagic acid in range from 8.0 × 10 -10 to 4.0 × 10 -5 mol L -1; and the detection limits are 3.2 × 10 -10 mol L -1 and 5.9 × 10 -10 mol L -1 excited at 266 nm and 388 nm, respectively. The actual samples of pomegranate rinds are simply manipulated and satisfactorily determined. The interaction mechanism studies argue that the negative EA-Borax complex is formed and solubilized in the cationic surfactant CTAB micelle in this system. The fluorescence intensity of EA enhances because the CTAB micelle provides a hydrophobic microenvironment for EA-Borax complex, which can prevent collision with water molecules and decrease the energy loss of EA-Borax complex.

Salicylic acid interferes with GFP fluorescence in vivo

PubMed Central

de Jonge, Jennifer; Hofius, Daniel

2017-01-01

Abstract Fluorescent proteins have become essential tools for cell biologists. They are routinely used by plant biologists for protein and promoter fusions to infer protein localization, tissue‐specific expression and protein abundance. When studying the effects of biotic stress on chromatin, we unexpectedly observed a decrease in GFP signal intensity upon salicylic acid (SA) treatment in Arabidopsis lines expressing histone H1-GFP fusions. This GFP signal decrease was dependent on SA concentration. The effect was not specific to the linker histone H1-GFP fusion but was also observed for the nucleosomal histone H2A-GFP fusion. This result prompted us to investigate a collection of fusion proteins, which included different promoters, subcellular localizations and fluorophores. In all cases, fluorescence signals declined strongly or disappeared after SA application. No changes were detected in GFP‐fusion protein abundance when fluorescence signals were lost indicating that SA does not interfere with protein stability but GFP fluorescence. In vitro experiments showed that SA caused GFP fluorescence reduction only in vivo but not in vitro, suggesting that SA requires cellular components to cause fluorescence reduction. Together, we conclude that SA can interfere with the fluorescence of various GFP‐derived reporter constructs in vivo. Assays that measure relocation or turnover of GFP‐tagged proteins upon SA treatment should therefore be evaluated with caution. PMID:28369601

Development of a facile and sensitive HPLC-FLD method via fluorescence labeling for triterpenic acid bioavailability investigation.

PubMed

You, Jinmao; Wu, Di; Zhao, Mei; Li, Guoliang; Gong, Peiwei; Wu, Yueyue; Guo, Yu; Chen, Guang; Zhao, Xianen; Sun, Zhiwei; Xia, Lian; Wu, Yongning

2017-06-01

Triterpenic acids are widely distributed in many fruits and are known for their medicinal benefits. The study of bioavailability has been an important task for a better understanding of the triterpenic acids. Although many methods based on fluorescence labeling for triterpenic acid determination have been established, these reported methods needed anhydrous conditions, which are not suitable for the convenient study of triterpenic acid bioavailability. Inspired by that, a versatile method, which overcomes the difficulty of the reported methods, has been first developed in this study. The novel method using 2-[12-benzo[b]acridin-5- (12H)-yl]-acetohydrazide (BAAH) as the fluorescence labeling reagent coupled with high-performance liquid chromatography with fluorescence detection was first developed for the study of triterpenic acid bioavailability. Furthermore, the labeling conditions have been optimized in order to achieve the best fluorescence labeling yield. Under the optimal conditions, the quantitative linear range of analytes was 2-1000 ng mL -1 , and the correlation coefficients were >0.9998. The detection limits for all triterpenic acid derivatives were achieved within the range of 0.28-0.29 ng mL -1 . The proposed method was successfully applied to the study of triterpenic acid bioavailability with excellent applicability and good reproducibility. Copyright © 2016 John Wiley & Sons, Ltd.

Position-specific incorporation of fluorescent non-natural amino acids into maltose-binding protein for detection of ligand binding by FRET and fluorescence quenching.

PubMed

Iijima, Issei; Hohsaka, Takahiro

2009-04-17

Position-specific incorporation of fluorescent groups is a useful method for analysis of the functions and structures of proteins. We have developed a method for the incorporation of visible-wavelength-fluorescent non-natural amino acids into proteins in a cell-free translation system. Using this technique, we introduced one or two BODIPY-linked amino acids into maltose-binding protein (MBP) to obtain MBP derivatives showing ligand-dependent changes in fluorescence intensity or intensity ratio. BODIPY-FL-aminophenylalanine was incorporated in place of 15 tyrosines, as well as the N-terminal Lys1, and the C-terminal Lys370 of MBP. Fluorescence measurements revealed that MBP containing a BODIPY-FL moiety in place of Tyr210 showed a 13-fold increase in fluorescence upon binding of maltose. Tryptophan-to-phenylalanine substitutions suggest that the increase in fluorescence was the result of a decrease in the quenching of BODIPY-FL by tryptophan located around the binding site. MBP containing a BODIPY-558 moiety also showed a maltose-dependent increase in fluorescence. BODIPY-FL was then additionally incorporated in place of Lys1 of the BODIPY-558-containing MBP as a response to the amber codon. Fluorescence measurements with excitation of BODIPY-FL showed a large change in fluorescence intensity ratio (0.13 to 1.25) upon binding of maltose; this change can be attributed to fluorescence resonance energy transfer (FRET) and maltose-dependent quenching of BODIPY-558. These results demonstrate the usefulness of the position-specific incorporation of fluorescent amino acids in the fluorescence-based detection of protein functions.

Delineating Normal from Diseased Brain by Aminolevulinic Acid-Induced Fluorescence

NASA Astrophysics Data System (ADS)

Stepp, Herbert; Stummer, Walter

5-Aminolevulinic acid (5-ALA) as a precursor of protoporphyrin IX (PpIX) has been established as an orally applied drug to guide surgical resection of malignant brain tumors by exciting the red fluorescence of PpIX. The accumulation of PpIX in glioblastoma multiforme (GBM) is highly selective and provides excellent contrast to normal brain when using surgical microscopes with appropriately filtered light sources and cameras. The positive predictive value of fluorescent tissue is very high, enabling safe gross total resection of GBM and other brain tumors and improving prognosis of patients. Compared to other intraoperative techniques that have been developed with the aim of increasing the rate of safe gross total resections of malignant gliomas, PpIX fluorescence is considerably simpler, more cost effective, and comparably reliable. We present the basics of 5-ALA-based fluorescence-guided resection, and discuss the clinical results obtained for GBM and the experience with the fluorescence staining of other primary brain tumors and metastases as well as the results for spinal cord tumors. The phototoxicity of PpIX, increasingly used for photodynamic therapy of brain tumors, is mentioned briefly in this chapter.

A new boronic acid fluorescent sensor based on fluorene for monosaccharides at physiological pH.

PubMed

Hosseinzadeh, Rahman; Mohadjerani, Maryam; Pooryousef, Mona; Eslami, Abbas; Emami, Saeed

2015-06-05

Fluorescent boronic acids are very useful fluorescent sensor for detection of biologically important saccharides. Herein we synthesized a new fluorene-based fluorescent boronic acid that shows significant fluorescence changes upon addition of saccharides at physiological pH. Upon addition of fructose, sorbitol, glucose, galactose, ribose, and maltose at different concentration to the solution of 7-(dimethylamino)-9,9-dimethyl-9H-fluoren-2-yl-2-boronic acid (7-DMAFBA, 1), significant decreases in fluorescent intensity were observed. It was found that this boronic acid has high affinity (K(a)=3582.88 M(-1)) and selectivity for fructose over glucose at pH=7.4. The sensor 1 showed a linear response toward d-fructose in the concentrations ranging from 2.5×10(-5) to 4×10(-4) mol L(-1) with the detection limit of 1.3×10(-5) mol L(-1). Copyright © 2015 Elsevier B.V. All rights reserved.

Sensitive detection of strong acidic condition by a novel rhodamine-based fluorescent pH chemosensor.

PubMed

Tan, Jia-Lian; Yang, Ting-Ting; Liu, Yu; Zhang, Xue; Cheng, Shu-Jin; Zuo, Hua; He, Huawei

2016-05-01

A novel rhodamine-based fluorescent pH probe responding to extremely low pH values has been synthesized and characterized. This probe showed an excellent photophysical response to pH on the basis that the colorless spirocyclic structure under basic conditions opened to a colored and highly fluorescent form under extreme acidity. The quantitative relationship between fluorescence intensity and pH value (1.75-2.62) was consistent with the equilibrium equation pH = pKa + log[(Imax - I)/(I - Imin)]. This sensitive pH probe was also characterized with good reversibility and no interaction with interfering metal ions, and was successfully applied to image Escherichia coli under strong acidity. Copyright © 2015 John Wiley & Sons, Ltd.

Folic acid-targeted magnetic Tb-doped CeF3 fluorescent nanoparticles as bimodal probes for cellular fluorescence and magnetic resonance imaging.

PubMed

Ma, Zhi-Ya; Liu, Yu-Ping; Bai, Ling-Yu; An, Jie; Zhang, Lin; Xuan, Yang; Zhang, Xiao-Shuai; Zhao, Yuan-Di

2015-10-07

Magnetic fluorescent nanoparticles (NPs) have great potential applications for diagnostics, imaging and therapy. We developed a facile polyol method to synthesize multifunctional Fe3O4@CeF3:Tb@CeF3 NPs with small size (<20 nm), high water solubility and good biocompatibility. The NPs were modified by ligand exchange reactions with citric acid (CA) to obtain carboxyl-functionalized NPs (Fe3O4@CeF3:Tb@CeF3-COOH). Folic acid (FA) as an affinity ligand was then covalently conjugated onto NPs to yield Fe3O4@CeF3:Tb@CeF3-FA NPs. They were then applied as multimodal imaging agents for simultaneous in vitro targeted fluorescence imaging and magnetic resonance imaging (MRI) of HeLa cells with overexpressed folate receptors (FR). The results indicated that these NPs had strong luminescence and enhanced T2-weighted MR contrast and would be promising candidates as multimodal probes for both fluorescence and MRI imaging.

Zinc complexes as fluorescent chemosensors for nucleic acids: new perspectives for a "boring" element.

PubMed

Terenzi, Alessio; Lauria, Antonino; Almerico, Anna Maria; Barone, Giampaolo

2015-02-28

Zinc(II) complexes are effective and selective nucleic acid-binders and strongly fluorescent molecules in the low energy range, from the visible to the near infrared. These two properties have often been exploited to quantitatively detect nucleic acids in biological samples, in both in vitro and in vivo models. In particular, the fluorescent emission of several zinc(II) complexes is drastically enhanced or quenched by the binding to nucleic acids and/or upon visible light exposure, in a different fashion in bulk solution and when bound to DNA. The twofold objective of this perspective is (1) to review recent utilisations of zinc(II) complexes as selective fluorescent probes for nucleic acids and (2) to highlight their novel potential applications as diagnostic tools based on their photophysical properties.

Engineering 'Golden' Fluorescence by Selective Pressure Incorporation of Non-canonical Amino Acids and Protein Analysis by Mass Spectrometry and Fluorescence.

PubMed

Baumann, Tobias; Schmitt, Franz-Josef; Pelzer, Almut; Spiering, Vivian Jeanette; Freiherr von Sass, Georg Johannes; Friedrich, Thomas; Budisa, Nediljko

2018-04-27

Fluorescent proteins are fundamental tools for the life sciences, in particular for fluorescence microscopy of living cells. While wild-type and engineered variants of the green fluorescent protein from Aequorea victoria (avGFP) as well as homologs from other species already cover large parts of the optical spectrum, a spectral gap remains in the near-infrared region, for which avGFP-based fluorophores are not available. Red-shifted fluorescent protein (FP) variants would substantially expand the toolkit for spectral unmixing of multiple molecular species, but the naturally occurring red-shifted FPs derived from corals or sea anemones have lower fluorescence quantum yield and inferior photo-stability compared to the avGFP variants. Further manipulation and possible expansion of the chromophore's conjugated system towards the far-red spectral region is also limited by the repertoire of 20 canonical amino acids prescribed by the genetic code. To overcome these limitations, synthetic biology can achieve further spectral red-shifting via insertion of non-canonical amino acids into the chromophore triad. We describe the application of SPI to engineer avGFP variants with novel spectral properties. Protein expression is performed in a tryptophan-auxotrophic E. coli strain and by supplementing growth media with suitable indole precursors. Inside the cells, these precursors are converted to the corresponding tryptophan analogs and incorporated into proteins by the ribosomal machinery in response to UGG codons. The replacement of Trp-66 in the enhanced "cyan" variant of avGFP (ECFP) by an electron-donating 4-aminotryptophan results in GdFP featuring a 108 nm Stokes shift and a strongly red-shifted emission maximum (574 nm), while being thermodynamically more stable than its predecessor ECFP. Residue-specific incorporation of the non-canonical amino acid is analyzed by mass spectrometry. The spectroscopic properties of GdFP are characterized by time-resolved fluorescence

[Acidity and temperature effect on the fluorescence characteristics of hydraulic oils and lubricants].

PubMed

Deng, Hu; Zhou, Xun; Shang, Li-ping; Zhang, Ze-lin; Wang, Shun-li

2014-12-01

By analyzing HyJet V phosphate ester hydraulic oil environmental impacts (oil, etc.) and confounding factors (pH, temperature, etc.), the feasibility was studied for the fluorescence detection of aircraft hydraulic oil leaks. By using the fluorescence spectrophotometer at various acidities and temperatures, the fluorescence properties of HyJet V phosphate ester hydraulic oil, Jet Oil II lubricant and 2197 lubricant were gained. The experimental results are shown as following: The fluorescence peaks of HyJet V phosphate ester hydraulic oil, Jet Oil II lubricant and 2197 lubricant are at 362, 405 and 456 nm, respectively. The impact of temperature on HyJet V phosphate ester hydraulic oil is less effective; Jet Oil II lubricant and 2197 lubricant fluorescence intensity decreases with increasing temperature. When acidity increases, the fluorescence peak of HyJet V phosphate ester hydraulic oil gradient shifts from 370 to 362 nm, and the fluorescence intensity decreases; the fluorescence peak of Jet Oil II lubricant is always 405 nm, while the fluorescence intensity decreases; the fluorescence peak of 2197 lubricant at 456 nm red shifts to 523 nm, and double fluorescence peaks appeare. The results are shown as following: under the influence of the environment and interference factors, the fluorescence characteristics of HyJet V phosphate ester hydraulic oil remain unchanged, and distinguish from Jet Oil II lubricant and 2197 lubricant. Therefore, the experiments indicate that the detection of HyJet V phosphate ester hydraulic oil leak is feasible by using fluorescence method.

Salicylic acid interferes with GFP fluorescence in vivo.

PubMed

de Jonge, Jennifer; Hofius, Daniel; Hennig, Lars

2017-03-01

Fluorescent proteins have become essential tools for cell biologists. They are routinely used by plant biologists for protein and promoter fusions to infer protein localization, tissue-specific expression and protein abundance. When studying the effects of biotic stress on chromatin, we unexpectedly observed a decrease in GFP signal intensity upon salicylic acid (SA) treatment in Arabidopsis lines expressing histone H1-GFP fusions. This GFP signal decrease was dependent on SA concentration. The effect was not specific to the linker histone H1-GFP fusion but was also observed for the nucleosomal histone H2A-GFP fusion. This result prompted us to investigate a collection of fusion proteins, which included different promoters, subcellular localizations and fluorophores. In all cases, fluorescence signals declined strongly or disappeared after SA application. No changes were detected in GFP-fusion protein abundance when fluorescence signals were lost indicating that SA does not interfere with protein stability but GFP fluorescence. In vitro experiments showed that SA caused GFP fluorescence reduction only in vivo but not in vitro, suggesting that SA requires cellular components to cause fluorescence reduction. Together, we conclude that SA can interfere with the fluorescence of various GFP-derived reporter constructs in vivo. Assays that measure relocation or turnover of GFP-tagged proteins upon SA treatment should therefore be evaluated with caution. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

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.

Transient Fluorescence Spectroscopy and laser induced fluorescence lifetimes of terbium doped dipicolinic acid

NASA Astrophysics Data System (ADS)

Makoui, Anali

We have investigated the use of deep UV laser induced fluorescence for the sensitive detection and spectroscopic lifetime studies of terbium doped dipicolinic acid (DPA-Tb) and used this to study the optical characteristics of DPA which is a chemical surrounding most bacterial spores. Background absorption spectra, fluorescence spectra, and Excitation Emission Matrix (EEM) spectra were made of the DPA-Tb complex, using both fixed 266 nm wavelength and tunable (220 nm--280 nm) UV laser excitations. Of importance, the fluorescence lifetimes of the four main fluorescence peaks (488 nm, 543 nm, 581 nm, and 618 nm) of the DPA-Tb complex have been measured for the first time to our knowledge. The lifetimes of all the fluorescing lines have been measured as a function of DPA-Tb concentration, solvent pH, and solvent composition, including that for the weakest fluorescing line of DPA-Tb at 618 nm. In addition, a new spectroscopic lifetime measurement technique, which we call "Transient Fluorescence Spectroscopy", was developed. In this technique, a weak, quasi-CW, amplitude modulated UV laser (8.5 kHz) was used to measure the lifetimes of the fluorescence lines, and yields insight into energy transfer and excitation lifetimes within the system. This technique is especially useful when a high power laser is not either available or not suitable. In the latter case, this would be when a high power pulsed deep-UV laser could produce bleaching or destruction of the biological specimen. In addition, this technique simulated the excitation and fluorescence emission of the DPA-Tb using a 4-level energy model, and solved the dynamic transient rate equations to predict the temporal behavior of the DPA-Tb emitted fluorescence. Excellent agreement between the experiments and the simulation were found. This technique has the potential to provide a more accurate value for the fluorescence lifetime values. In addition, with the use of asymmetric excitation waveforms, the dynamic

Evaluation of acridine orange, LysoTracker Red, and quinacrine as fluorescent probes for long-term tracking of acidic vesicles.

PubMed

Pierzyńska-Mach, Agnieszka; Janowski, Paweł A; Dobrucki, Jurek W

2014-08-01

Acidic vesicles can be imaged and tracked in live cells after staining with several low molecular weight fluorescent probes, or with fluorescently labeled proteins. Three fluorescent dyes, acridine orange, LysoTracker Red DND-99, and quinacrine, were evaluated as acidic vesicle tracers for confocal fluorescence imaging and quantitative analysis. The stability of fluorescent signals, achievable image contrast, and phototoxicity were taken into consideration. The three tested tracers exhibit different advantages and pose different problems in imaging experiments. Acridine orange makes it possible to distinguish acidic vesicles with different internal pH but is fairly phototoxic and can cause spectacular bursts of the dye-loaded vesicles. LysoTracker Red is less phototoxic but its rapid photobleaching limits the range of useful applications considerably. We demonstrate that quinacrine is most suitable for long-term imaging when a high number of frames is required. This capacity made it possible to trace acidic vesicles for several hours, during a process of drug-induced apoptosis. An ability to record the behavior of acidic vesicles over such long periods opens a possibility to study processes like autophagy or long-term effects of drugs on endocytosis and exocytosis. © 2014 International Society for Advancement of Cytometry.

Strong Fluorescent Smart Organogel as a Dual Sensing Material for Volatile Acid and Organic Amine Vapors.

PubMed

Xue, Pengchong; Yao, Boqi; Wang, Panpan; Gong, Peng; Zhang, Zhenqi; Lu, Ran

2015-11-23

An L-phenylalanine derivative (C12PhBPCP) consisting of a strong emission fluorophore with benzoxazole and cyano groups is designed and synthesized to realize dual responses to volatile acid and organic amine vapors. The photophysical properties and self-assembly of the said derivative in the gel phase are also studied. C12PhBPCP can gelate organic solvents and self-assemble into 1 D nanofibers in the gels. UV/Vis absorption spectral results show H-aggregate formation during gelation, which indicates strong exciton coupling between fluorophores. Both wet gel and xerogel emit strong green fluorescence because the cyano group suppresses fluorescence quenching in the self-assemblies. Moreover, the xerogel film with strong green fluorescence can be used as a dual chemosensor for quantitative detection of volatile acid and organic amine vapors with fast response times and low detection limits owing to its large surface area and amplified fluorescence quenching. The detection limits are 796 ppt and 25 ppb for gaseous aniline and trifluoroacetic acid (TFA), respectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Red-emitting fluorescent probe for detecting hypochlorite acid in vitro and in vivo.

PubMed

Chen, Hong; Sun, Tao; Qiao, Xiao-Guang; Tang, Qian-Oian; Zhao, Shan-Chao; Zhou, Zhan

2018-06-12

Due to the importance of hypochlorous acid (HClO) in biological and industrial, development of fluorescent probes for HClO has been an active research area. Here, a new red-emitting ratiometric fluorescent probe (P) was synthesized and well defined characterization via NMR, HR-MS, and fluorescence spectrum, which serves as a selective and sensitive probe for ClO - group. The probe showed a ratiometric fluorescent response to hypochlorite at the emission intensities ratio (I 480 /I 612 ) increasing from 0.28 to 27.46. The emission intensities ratio (I 480 /I 612 ) was linearly enhanced (I 480 /I 612  = 0.064 X + 0.096) with the ClO - concentration range from 1 to 30 μM. The detection limitation for ClO - in aqueous solution is 0.47 μM. Moreover, this biocompatible red-emitting ratiometric fluorescent probe was utilized to the fluorescence imaging of ClO - in living cells and Zebrafish. Copyright © 2018. Published by Elsevier B.V.

A carbon dot-based "off-on" fluorescent probe for highly selective and sensitive detection of phytic acid.

PubMed

Gao, Zhao; Wang, Libing; Su, Rongxin; Huang, Renliang; Qi, Wei; He, Zhimin

2015-08-15

We herein report a facile, one-step pyrolysis synthesis of photoluminescent carbon dots (CDs) using citric acid as the carbon source and lysine as the surface passivation reagent. The as-prepared CDs show narrow size distribution, excellent blue fluorescence and good photo-stability and water dispersivity. The fluorescence of the CDs was found to be effectively quenched by ferric (Fe(III)) ions with high selectivity via a photo-induced electron transfer (PET) process. Upon addition of phytic acid (PA) to the CDs/Fe(III) complex dispersion, the fluorescence of the CDs was significantly recovered, arising from the release of Fe(III) ions from the CDs/Fe(III) complex because PA has a higher affinity for Fe(III) ions compared to CDs. Furthermore, we developed an "off-on" fluorescence assay method for the detection of phytic acid using CDs/Fe(III) as a fluorescent probe. This probe enables the selective detection of PA with a linear range of 0.68-18.69 μM and a limit of detection (signal-to-noise ratio is 3) of 0.36 μM. The assay method demonstrates high selectivity, repeatability, stability and recovery ratio in the detection of the standard and real PA samples. We believe that the facile operation, low-cost, high sensitivity and selectivity render this CD-based "off-on" fluorescent probe an ideal sensing platform for the detection of PA. Copyright © 2015 Elsevier B.V. All rights reserved.

Studies on fatty acid-binding proteins. The detection and quantification of the protein from rat liver by using a fluorescent fatty acid analogue.

PubMed Central

Wilkinson, T C; Wilton, D C

1986-01-01

Fatty acid-binding protein from rat liver is shown to bind the fluorescent fatty acid probe dansyl undecanoic acid. Binding is accompanied by a shift in the fluorescence emission maximum from 550 nm to 500 nm and a 60-fold fluorescence enhancement at 500 nm. These spectral properties have allowed the use of this probe to detect and quantify microgram amounts of liver fatty acid-binding protein during purification procedures. In conjunction with h.p.l.c. the method allows the rapid estimation of liver fatty acid-binding protein in biological samples. The validity of the method is demonstrated by measuring the concentration of fatty acid-binding protein in livers from control and hypolipidaemic-drug-treated rats. The dramatic diurnal rhythm previously reported for this protein [Dempsey (1984) Curr. Top. Cell. Regul. 24, 63-86] was not observed with this method. Images Fig. 1. PMID:3800946

Dual fluorescence of N-phenylanthranilic acid: Effect of solvents, pH and beta-cyclodextrin.

PubMed

Rajendiran, N; Balasubramanian, T

2007-11-01

Spectral characteristics of N-phenylanthranilic acid (NPAA) have been studied in different solvents, pH and beta-cyclodextrin (beta-CD) and compared with anthranilic acid (2-aminobenzoic acid, 2ABA). In all solvents a dual fluorescence is observed in NPAA, whereas 2ABA gives single emission. Combining the results observed in the absorption, fluorescence emission and fluorescence excitation spectra, it is found that strong intramolecular hydrogen bonding (IHB) interactions present in NPAA molecule. The inclusion complex of NPAA with beta-CD is analysed by UV-vis, fluorimetry, FT-IR, (1)H NMR, scanning electron microscope and AM 1 method. The above spectral studies show that NPAA forms a 1:1 inclusion complex with beta-CD and COOH group present in the beta-CD cavity. A mechanism is proposed to explain the inclusion process.

Dual fluorescence of N-phenylanthranilic acid: Effect of solvents, pH and β-cyclodextrin

NASA Astrophysics Data System (ADS)

Rajendiran, N.; Balasubramanian, T.

2007-11-01

Spectral characteristics of N-phenylanthranilic acid (NPAA) have been studied in different solvents, pH and β-cyclodextrin (β-CD) and compared with anthranilic acid (2-aminobenzoic acid, 2ABA). In all solvents a dual fluorescence is observed in NPAA, whereas 2ABA gives single emission. Combining the results observed in the absorption, fluorescence emission and fluorescence excitation spectra, it is found that strong intramolecular hydrogen bonding (IHB) interactions present in NPAA molecule. The inclusion complex of NPAA with β-CD is analysed by UV-vis, fluorimetry, FT-IR, 1H NMR, scanning electron microscope and AM 1 method. The above spectral studies show that NPAA forms a 1:1 inclusion complex with β-CD and COOH group present in the β-CD cavity. A mechanism is proposed to explain the inclusion process.

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.

Nanoparticle-enhanced fluorescence emission for non-separation assays of carbohydrates using a boronic acid-alizarin complex.

PubMed

Li, Qianjin; Kamra, Tripta; Ye, Lei

2016-03-04

Addition of crosslinked polymer nanoparticles into a solution of a 3-nitrophenylboronic acid-alizarin complex leads to significant enhancement of fluorescence emission. Using the nanoparticle-enhanced boronic acid-alizarin system has improved greatly the sensitivity and extended the dynamic range of separation-free fluorescence assays for carbohydrates.

Intrinsic protein fluorescence interferes with detection of tear glycoproteins in SDS-polyacrylamide gels using extrinsic fluorescent dyes.

PubMed

Zhao, Zhenjun; Aliwarga, Yulina; Willcox, Mark D P

2007-12-01

Intrinsic protein fluorescence may interfere with the visualization of proteins after SDS-polyacrylamide electrophoresis. In an attempt to analyze tear glycoproteins in gels, we ran tear samples and stained the proteins with a glycoprotein-specific fluorescent dye. The fluorescence detected was not limited to glycoproteins. There was strong intrinsic fluorescence of proteins normally found in tears after soaking the gels in 40% methanol plus 1-10% acetic acid and, to a lesser extent, in methanol or acetic acid alone. Nanograms of proteins gave visible native fluorescence and interfere with extrinsic fluorescent dye detection. Poly-L-lysine, which does not contain intrinsically fluorescent amino acids, did not fluoresce.

Intrinsic Protein Fluorescence Interferes with Detection of Tear Glycoproteins in SDS-Polyacrylamide Gels Using Extrinsic Fluorescent Dyes

PubMed Central

Zhao, Zhenjun; Aliwarga, Yulina; Willcox, Mark DP

2007-01-01

Intrinsic protein fluorescence may interfere with the visualization of proteins after SDS-polyacrylamide electrophoresis. In an attempt to analyze tear glycoproteins in gels, we ran tear samples and stained the proteins with a glycoprotein-specific fluorescent dye. The fluorescence detected was not limited to glycoproteins. There was strong intrinsic fluorescence of proteins normally found in tears after soaking the gels in 40% methanol plus 1–10% acetic acid and, to a lesser extent, in methanol or acetic acid alone. Nanograms of proteins gave visible native fluorescence and interfere with extrinsic fluorescent dye detection. Poly-L-lysine, which does not contain intrinsically fluorescent amino acids, did not fluoresce. PMID:18166676

Terbium-Aspartic Acid Nanocrystals with Chirality-Dependent Tunable Fluorescent Properties.

PubMed

Ma, Baojin; Wu, Yu; Zhang, Shan; Wang, Shicai; Qiu, Jichuan; Zhao, Lili; Guo, Daidong; Duan, Jiazhi; Sang, Yuanhua; Li, Linlin; Jiang, Huaidong; Liu, Hong

2017-02-28

Terbium-aspartic acid (Tb-Asp) nanocrystals with chirality-dependent tunable fluorescent properties can be synthesized through a facile synthesis method through the coordination between Tb and Asp. Asp with different chirality (dextrorotation/d and levogyration/l) changes the stability of the coordination center following fluorescent absorption/emission ability differences. Compared with l-Asp, d-Asp can coordinate Tb to form a more stable center, following the higher quantum yield and longer fluorescence life. Fluorescence intensity of Tb-Asp linearly increases with increase ratio of d-Asp in the mixed chirality Tb-Asp system, and the fluorescent properties of Tb-Asp nanocrystals can be tuned by adjusting the chirality ratio. Tb-Asp nanocrystals possess many advantage, such as high biocompatibility, without any color in visible light irradiation, monodispersion with very small size, and long fluorescent life. Those characteristics will give them great potential in many application fields, such as low-cost antifake markers and advertisements using inkjet printers or for molds when dispersed in polydimethylsiloxane. In addition, europium can also be used to synthesize Eu-Asp nanoparticles. Importantly, the facile, low-cost, high-yield, mass-productive "green" process provides enormous advantages for synthesis and application of fluorescent nanocrystals, which will have great impact in nanomaterial technology.

Fluorescence properties of 3-amino phenylboronic acid and its interaction with glucose and ZnS:Cu quantum dots.

PubMed

Kur-Kowalska, Karolina; Przybyt, Małgorzata; Ziółczyk, Paulina; Sowiński, Przemysław; Miller, Ewa

2014-08-14

Preliminary results of a study of the interaction between 3-amino phenylboronic acid and glucose or ZnS:Cu quantum dots are presented in this paper. ZnS:Cu quantum dots with mercaptopropionic acid as a capping agent were obtained and characterized. Quenching of 3-amino phenylboronic acid fluorescence was studied by steady-state and timeresolved measurements. For fluorescence quenching with glucose the results of steady-state measurements fulfill Stern-Volmer equation. The quenching constants are increasing with growing pH. The decay of fluorescence is monoexponential with lifetime about 8.4 ns, which does not depend on pH and glucose concentration indicating static quenching. The quenching constant can be interpreted as apparent equilibrium constant of estrification of boronic group with diol. Quantum dots are also quenching 3-amino phenylboronic acid fluorescence. Fluorescence lifetime, in this case, is slightly decreasing with increasing concentration of quantum dots. The quenching constants are increasing slightly with pH's growth. Quenching mechanism of 3-amino phenylboronic acid fluorescence by quantum dots needs further experiments to be fully explained. Copyright © 2014 Elsevier B.V. All rights reserved.

Imaging of intracellular fatty acids by scanning X-ray fluorescence microscopy

PubMed Central

Shimura, Mari; Shindou, Hideo; Szyrwiel, Lukasz; Tokuoka, Suzumi M.; Hamano, Fumie; Matsuyama, Satoshi; Okamoto, Mayumi; Matsunaga, Akihiro; Kita, Yoshihiro; Ishizaka, Yukihito; Yamauchi, Kazuto; Kohmura, Yoshiki; Lobinski, Ryszard; Shimizu, Isao; Shimizu, Takao

2016-01-01

Fatty acids are taken up by cells and incorporated into complex lipids such as neutral lipids and glycerophospholipids. Glycerophospholipids are major constituents of cellular membranes. More than 1000 molecular species of glycerophospholipids differ in their polar head groups and fatty acid compositions. They are related to cellular functions and diseases and have been well analyzed by mass spectrometry. However, intracellular imaging of fatty acids and glycerophospholipids has not been successful due to insufficient resolution using conventional methods. Here, we developed a method for labeling fatty acids with bromine (Br) and applied scanning X-ray fluorescence microscopy (SXFM) to obtain intracellular Br mapping data with submicrometer resolution. Mass spectrometry showed that cells took up Br-labeled fatty acids and metabolized them mainly into glycerophospholipids in CHO cells. Most Br signals observed by SXFM were in the perinuclear region. Higher resolution revealed a spot-like distribution of Br in the cytoplasm. The current method enabled successful visualization of intracellular Br-labeled fatty acids. Single-element labeling combined with SXFM technology facilitates the intracellular imaging of fatty acids, which provides a new tool to determine dynamic changes in fatty acids and their derivatives at the single-cell level.—Shimura, M., Shindou, H., Szyrwiel, L., Tokuoka, S. M., Hamano, F., Matsuyama, S., Okamoto, M., Matsunaga, A., Kita, Y., Ishizaka, Y., Yamauchi, K., Kohmura, Y., Lobinski, R., Shimizu, I., Shimizu, T. Imaging of intracellular fatty acids by scanning X-ray fluorescence microscopy. PMID:27601443

Heterogeneous accumulation of fluorescent bile acids in primary rat hepatocytes does not correlate with their homogenous expression of ntcp.

PubMed

Murray, John W; Thosani, Amar J; Wang, Pijun; Wolkoff, Allan W

2011-07-01

Sodium taurocholate-cotransporting polypeptide (ntcp) is considered to be a major determinant of bile acid uptake into hepatocytes. However, the regulation of ntcp and the degree that it participates in the accumulation of specific substrates are not well understood. We utilized fluorescent bile acid derivatives and direct quantitation of fluorescent microscopy images to examine the regulation of ntcp and its role in the cell-to-cell variability of fluorescent bile acid accumulation. Primary-cultured rat hepatocytes rapidly accumulated the fluorescent bile acids, chenodeoxycholylglycylamidofluorescein (CDCGamF), 7-β- nitrobenzoxadiazole 3-α hydroxy 5-β cholan-24-oic acid (NBD-CA), and cholyl-glycylamido-fluorescein (CGamF). However, in stably transfected HeLa cells, ntcp preferred CDCGamF, whereas the organic anion transporter, organic anion transporting polypeptide 1 (oatp1a1), preferred NBD-CA, and neither ntcp nor oatp1a1 showed strong accumulation of CGamF by these methods. Ntcp-mediated transport of CDCGamF was inhibited by taurocholate, cyclosporin, actin depolymerization, and an inhibitor of atypical PKC-ζ. The latter two agents altered the cellular distribution of ntcp as visualized in ntcp-green fluorescent protein-transfected cells. Although fluorescent bile acid accumulation was reproducible by the imaging assays, individual cells showed variable accumulation that was not attributable to changes in membrane permeability or cell viability. In HeLa cells, this was accounted for by variable levels of ntcp, whereas, in hepatocytes, ntcp expression was uniform, and low accumulation was seen in a large portion of cells despite the presence of ntcp. These studies indicate that single-cell imaging can provide insight into previously unrecognized details of anion transport in the complex environment of polarized hepatocytes.

Heterogeneous accumulation of fluorescent bile acids in primary rat hepatocytes does not correlate with their homogenous expression of ntcp

PubMed Central

Thosani, Amar J.; Wang, Pijun; Wolkoff, Allan W.

2011-01-01

Sodium taurocholate-cotransporting polypeptide (ntcp) is considered to be a major determinant of bile acid uptake into hepatocytes. However, the regulation of ntcp and the degree that it participates in the accumulation of specific substrates are not well understood. We utilized fluorescent bile acid derivatives and direct quantitation of fluorescent microscopy images to examine the regulation of ntcp and its role in the cell-to-cell variability of fluorescent bile acid accumulation. Primary-cultured rat hepatocytes rapidly accumulated the fluorescent bile acids, chenodeoxycholylglycylamidofluorescein (CDCGamF), 7-β- nitrobenzoxadiazole 3-α hydroxy 5-β cholan-24-oic acid (NBD-CA), and cholyl-glycylamido-fluorescein (CGamF). However, in stably transfected HeLa cells, ntcp preferred CDCGamF, whereas the organic anion transporter, organic anion transporting polypeptide 1 (oatp1a1), preferred NBD-CA, and neither ntcp nor oatp1a1 showed strong accumulation of CGamF by these methods. Ntcp-mediated transport of CDCGamF was inhibited by taurocholate, cyclosporin, actin depolymerization, and an inhibitor of atypical PKC-ζ. The latter two agents altered the cellular distribution of ntcp as visualized in ntcp-green fluorescent protein-transfected cells. Although fluorescent bile acid accumulation was reproducible by the imaging assays, individual cells showed variable accumulation that was not attributable to changes in membrane permeability or cell viability. In HeLa cells, this was accounted for by variable levels of ntcp, whereas, in hepatocytes, ntcp expression was uniform, and low accumulation was seen in a large portion of cells despite the presence of ntcp. These studies indicate that single-cell imaging can provide insight into previously unrecognized details of anion transport in the complex environment of polarized hepatocytes. PMID:21474652

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.

A halochromic stimuli-responsive reversible fluorescence switching 3, 4, 9, 10-perylene tetracarboxylic acid dye for fabricating rewritable platform

NASA Astrophysics Data System (ADS)

Hariharan, P. S.; Pitchaimani, J.; Madhu, Vedichi; Anthony, Savarimuthu Philip

2017-02-01

3, 4, 9, 10-perylene tetracarboxylic acid (PTCA), a strongly fluorescent water soluble dye with halochromic functionality showed pH dependent reversible fluorescence switching. The strong fluorescence of PTCA (Φf = 0.67) in basic medium was completely quenched upon acidification. The fluorescent PTCA has been transferred on to a solid substrate (filter paper and glass plate) that also showed reversible off-on fluorescence switching by acid/base and drying/water vapor exposure. The reversible fluorescence switching of PTCA could be of potential interest for fabricating rewritable fluorescent medium.

A novel turn-on fluorescent strategy for sensing ascorbic acid using graphene quantum dots as fluorescent probe.

PubMed

Liu, Hua; Na, Weidan; Liu, Ziping; Chen, Xueqian; Su, Xingguang

2017-06-15

In this paper, a facile and rapid fluorescence turn-on assay for fluorescent detection of ascorbic acid (AA) was developed by using the orange emission graphene quantum dots (GQDs). In the presence of horse radish peroxidase (HRP) and hydrogen peroxide (H 2 O 2 ), catechol can be oxidized by hydroxyl radicals and converted to o-benzoquinone, which can significantly quench the fluorescence of GQDs. However, when AA present in the system, it can consume part of H 2 O 2 and hydroxyl radicals to inhibit the generation of o-benzoquinone, resulting in fluorescence recovery. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of H 2 O 2 in the range of 3.33-500µM with a detection limit of 1.2µM. The linear detection for AA was in the range from 1.11 to 300µM with a detection limit of 0.32µM. The proposed method was applied to the determination of AA in human serum samples with satisfactory results. Copyright © 2017. Published by Elsevier B.V.

Methods and kits for nucleic acid analysis using fluorescence resonance energy transfer

DOEpatents

Kwok, Pui-Yan; Chen, Xiangning

1999-01-01

A method for detecting the presence of a target nucleotide or sequence of nucleotides in a nucleic acid is disclosed. The method is comprised of forming an oligonucleotide labeled with two fluorophores on the nucleic acid target site. The doubly labeled oligonucleotide is formed by addition of a singly labeled dideoxynucleoside triphosphate to a singly labeled polynucleotide or by ligation of two singly labeled polynucleotides. Detection of fluorescence resonance energy transfer upon denaturation indicates the presence of the target. Kits are also provided. The method is particularly applicable to genotyping.

A water-soluble rhodamine B-derived fluorescent probe for pH monitoring and imaging in acidic regions

NASA Astrophysics Data System (ADS)

Cui, Peng; Jiang, Xuekai; Sun, Junyong; Zhang, Qiang; Gao, Feng

2017-06-01

A structurally simple, water-soluble rhodamine-derivatived fluorescent probe, which is responsive to acidic pH, was conveniently synthesized via a one-step condensation reaction of rhodamine B hydrazide and 4-formybenzene-1,3-disulfonate. As a stable and highly sensitive pH sensor, the probe displays an approximately 50-fold fluorescence enhancement over the pH range of 7.16-4.89 as the structure of probe changes from spirocyclic (weak fluorescent) to ring-open (strong fluorescent) with decreasing pH. The synthesized fluorescent probe is applied to the detection of pH changes in vitro and in vivo bioimaging of immortalized gastric cancer cells, with satisfactory results.

Exciton-controlled fluorescence: application to hybridization-sensitive fluorescent DNA probe.

PubMed

Okamoto, Akimitsu; Ikeda, Shuji; Kubota, Takeshi; Yuki, Mizue; Yanagisawa, Hiroyuki

2009-01-01

A hybridization-sensitive fluorescent probe has been designed for nucleic acid detection, using the concept of fluorescence quenching caused by the intramolecular excitonic interaction of fluorescence dyes. We synthesized a doubly thiazole orange-labeled nucleotide showing high fluorescence intensity for a hybrid with the target nucleic acid and effective quenching for the single-stranded state. This exciton-controlled fluorescent probe was applied to living HeLa cells using microinjection to visualize intracellular mRNA localization. Immediately after injection of the probe into the cell, fluorescence was observed from the probe hybridizing with the target RNA. This fluorescence rapidly decreased upon addition of a competitor DNA. Multicoloring of this probe resulted in the simple simultaneous detection of plural target nucleic acid sequences. This probe realized a large, rapid, reversible change in fluorescence intensity in sensitive response to the amount of target nucleic acid, and facilitated spatiotemporal monitoring of the behavior of intracellular RNA.

Fluorescence Behavior and Dural Infiltration of Meningioma Analyzed by 5-Aminolevulinic Acid-Based Fluorescence: Operating Microscope Versus Mini-Spectrometer.

PubMed

Knipps, Johannes; Beseoglu, Kerim; Kamp, Marcel; Fischer, Igor; Felsberg, Joerg; Neumann, Lisa M; Steiger, Hans-Jakob; Cornelius, Jan F

2017-12-01

To compare fluorescence intensity of tumor specimens, as measured by a fluorescence-guided surgery microscope and a spectrometer, to evaluate tumor infiltration of dura mater around meningiomas with help of these 2 different 5-aminolevulinic acid (5-ALA)-based fluorescence tools, and to correlate fluorescence intensity with histopathologic data. In a clinical series, meningiomas were resected by 5-ALA fluorescence-guided surgery. Fluorescence intensity was semiquantitatively rated by the surgeon at predefined points. Biopsies were harvested and fluorescence intensity measured by a spectrometer and histopathologically analyzed. Sampling was realized at the level of the dura in a centrifugal direction. A total of 104 biopsies (n = 13 tumors) were analyzed. Specificity and sensitivity of the microscope were 0.96 and 0.53 and of the spectrometer 0.95 and 0.93, respectively. Fluorescence intensity as measured by the spectrometer was correlated to histologically confirmed tumor burden. In a centrifugal direction, tumor burden and fluorescence intensity continuously decreased (along the dural tail). Below a threshold value of 639 arbitrary units no tumor was histologically detectable. At the level of the dura the spectrometer was highly sensitive for detection of meningioma cells. The surgical microscope showed false negative results and missed residual tumor cells in more than one half of the cases. The complementary use of both fluorescence tools may improve resection quality. Copyright © 2017 Elsevier Inc. All rights reserved.

DETECTION OF 2,4-DICHLOROPHENOXYACETIC ACID USING A FLUORESCENCE IMMUNOANALYZER

EPA Science Inventory

A flow immunoassay method for the measurement of 2,4-dichlorophenoxyacetic acid (2,4-D) was developed. The competitive fluorescence immunoassay relies on the use of antibody- or antigen-coated poly(methyl methacrylate) particles (98 um diameter) as a renewable solid phase. The as...

Preparation of a Trp-BODIPY fluorogenic amino acid to label peptides for enhanced live-cell fluorescence imaging.

PubMed

Mendive-Tapia, Lorena; Subiros-Funosas, Ramon; Zhao, Can; Albericio, Fernando; Read, Nick D; Lavilla, Rodolfo; Vendrell, Marc

2017-08-01

Fluorescent peptides are valuable tools for live-cell imaging because of the high specificity of peptide sequences for their biomolecular targets. When preparing fluorescent versions of peptides, labels must be introduced at appropriate positions in the sequences to provide suitable reporters while avoiding any impairment of the molecular recognition properties of the peptides. This protocol describes the preparation of the tryptophan (Trp)-based fluorogenic amino acid Fmoc-Trp(C 2 -BODIPY)-OH and its incorporation into peptides for live-cell fluorescence imaging-an approach that is applicable to most peptide sequences. Fmoc-Trp(C 2 -BODIPY)-OH contains a BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) fluorogenic core, which works as an environmentally sensitive fluorophore, showing high fluorescence in lipophilic conditions. It is attached to Trp via a spacer-free C-C linkage, resulting in a labeled amino acid that can mimic the molecular interactions of Trp, enabling wash-free imaging. This protocol covers the chemical synthesis of the fluorogenic amino acid Fmoc-Trp(C 2 -BODIPY)-OH (3-4 d), the preparation of the labeled antimicrobial peptide BODIPY-cPAF26 by solid-phase synthesis (6-7 d) and its spectral and biological characterization as a live-cell imaging probe for different fungal pathogens. As an example, we include a procedure for using BODIPY-cPAF26 for wash-free imaging of fungal pathogens, including real-time visualization of Aspergillus fumigatus (5 d for culturing, 1-2 d for imaging).

Fluorescence Quenching of Humic Acid by Coated Metallic Silver Particles.

PubMed

Zhu, Guocheng; Yin, Jun

2017-07-01

Natural organic matter is an important component of the aquatic environments, which has attracted wide attention to its influence of interaction with other pollutants. The present work aimed to investigate its fluorescence quenching (FQ) by coated metallic silver particles (AgNPs). In this work, using fluorescence spectroscopy in conjunction with UV-Vis spectroscopy and dynamic light scattering, the effect of coated AgNPs on fluorescence quenching intensity (FQI) of humic acid (HA) was assessed. In addition, the influence of electrolytes (NaCl, NaNO 3 and CaNO 3 ) in the FQI was observed. Results showed that with AgNPs dosage increased (>1.17X10 -3  mM), fluorescence quantum yield of HA gradually decreased, which implies that the FQ occurred. Furher observation showed that the FQ process followed both first-order and second-order Stern-Volmer functions. The FQ process was affected by the electrolytes: NaCl had an effect on reduction of FQI, possibly resulting from dissolution of AgNPs; Both of NaNO 3 and Ca(NO 3 ) 2 had an effect on the FQ of HA but Ca(NO 3 ) 2 presented greater degree. As a result, the FQ degree of HA by alone electrolyte was listed in descent order as Ca(NO 3 ) 2  > NaNO 3  > NaCl, which also implies the subsequent experimental results, indicating the FQ degree of HA by mutual electrolytes as Ca(NO 3 ) 2  + NaNO 3  > Ca(NO 3 ) 2  + NaCl > NaNO 3  + NaCl.

[Study of Reaction Dynamics between Bovine Serum Albumin and Folic Acid by Stopped-Flow/Fluorescence].

PubMed

Ye, San-xian; Luo, Yun-jing; Qiao, Shu-liang; Li, Li; Liu, Cai-hong; Shi, Jian-long; An, Xue-jing

2016-01-01

As a kind of coenzyme of one-carbon enzymes in vivo, folic acid belongs to B vitamins, which can interact with other vitamins and has great significance for converting among amino acids, dividing growth of cells and protein synthesis reactions. Half-life, concentration and reaction rate constant of drugs are important parameters in pharmacokinetic study. In this paper, by utilizing fluorescence spectrophotometer and stopped-flow spectrum analyzer, reaction kinetic parameters between bovine serum albumin(BSA) and folic acid in a bionic system have been investigated, which provide references for parameters of drug metabolism related to folic acid. By using Stern-Volmer equation dealing with fluorescence quenching experiments data, we concluded that under 25, 30, and 37 degrees C, the static quenching constants of folic acid to intrinsic fluorescence from bovine serum albumin were 2.455 x 10(10), 4.900 x 10(10) and 6.427 x 10(10) L x mol(-1) x s(-1) respectively; The results of kinetic reaction rate have shown that the reaction rate of BSA and folic acid are greater than 100 mol x L(-1) x s(-1) at different temperatures, pH and buffering media, illustrating that the quenching mechanism between BSA and folic acid is to form composite static quenching process. Reaction concentration of bovine serum albumin and its initial concentration were equal to the secondary reaction formula, and the correlation coefficient was 0.998 7, while the half-life (t1/2) was 0.059 s at physiological temperature. With the increase of folic acid concentration, the apparent rate constant of this reaction had a linear increasing trend, the BSA fluorescence quenching rate constant catalyzed by folic acid was 3.174 x 10(5) mol x L(-1) x s(-1). Furthermore, with different buffer, the apparent rate constant and reaction rate constant of BSA interacting with folic acid were detected to explore the influence on the reaction under physiological medium, which is of great significance to determine the

Curcumin-cysteine and curcumin-tryptophan conjugate as fluorescence turn on sensors for picric Acid in aqueous media.

PubMed

Gogoi, Bedanta; Sen Sarma, Neelotpal

2015-06-03

Rapid detection of picric acid in real sample is of outmost importance from the perspective of health, safety, and environment. In this study, a very simple and cost-effective detection of picric acid is accomplished by developing a couple of biobased conjugates curcumin-cysteine (CC) and curcumin-tryptophan (CT), which undergo efficient fluorescence turn on toward picric acid in aqueous media. Both the probes experience about 26.5-fold fluorescence enhancements at 70 nM concentration of the analyte. Here, the fluorescence turn on process is governed by the aggregation induced emission, which is induced from the electrostatic interaction between the conjugates with picric acid. The detection limit of CC and CT are about 13.51 and 13.54 nM of picric acid, respectively. Importantly, both the probes exhibit high selectivity and low interference of other analogues toward the detection of picric acid. In addition, the probes are highly photostable, show low response time and are practically applicable for sensing picric acid in real environmental samples, which is the ultimate goal of this work.

New fluorescent bile acids: synthesis, chemical characterization, and disastereoselective uptake by Caco-2 cells of 3-deoxy 3-NBD-amino deoxycholic and ursodeoxycholic acid.

PubMed

Májer, Ferenc; Salomon, Johanna J; Sharma, Ruchika; Etzbach, Simona V; Najib, Mohd Nadzri Mohd; Keaveny, Ray; Long, Aideen; Wang, Jun; Ehrhardt, Carsten; Gilmer, John F

2012-03-01

Deoxycholic acid (DCA), a secondary bile acid (BA), and ursodeoxycholic acid (UDCA), a tertiary BA, cause opposing effects in vivo and in cell suspensions. Fluorescent analogues of DCA and UDCA could help investigate important questions about their cellular interactions and distribution. We have prepared a set of isomeric 3α- and 3β-amino analogues of UDCA and DCA and derivatised these with the discrete fluorophore, 4-nitrobenzo-2-oxa-1,3-diazol (NBD), forming the corresponding four fluorescent adducts. These absorb in the range 465-470 nm and fluoresce at approx. 535 nm. In order to determine the ability of the new fluorescent bile acids to mimic the parents, their uptake was studied using monolayers of Caco-2 cells, which are known to express multiple proteins of the organic anion-transporting peptide (OATP) subfamily of transporters. Cellular uptake was monitored over time at 4 and 37°C to distinguish between passive and active transport. All four BA analogues were taken up but in a strikingly stereo- and structure-specific manner, suggesting highly discriminatory interactions with transporter protein(s). The α-analogues of DCA and to a lesser extent UDCA were actively transported, whereas the β-analogues were not. The active transport process was saturable, with Michaelis-Menten constants for 3α-NBD DCA (5) being K(m)=42.27±12.98 μM and V(max)=2.8 ± 0.4 nmol/(mg protein*min) and for 3α-NBD UDCA (3) K(m)=28.20 ± 7.45 μM and V(max)=1.8 ± 0.2 nmol/(mg protein*min). These fluorescent bile acids are promising agents for investigating questions of bile acid biology and for detection of bile acids and related organic anion transport processes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Self-assembled nanotubes from single fluorescent amino acid

NASA Astrophysics Data System (ADS)

Babar, Dipak Gorakh; Sarkar, Sabyasachi

2017-04-01

Self-assembly of biomolecules has gained increasing attention as it generates various supramolecular structural assemblies having potential applications principally in biomedical sciences. Here, we show that amino acid like tryptophan or tyrosine readily aggregates as nanotubes via a simple self-assembly process. These were characterized by FTIR, scanning electron microscopy, and by fluorescence microscopy. Nanotubes prepared from tryptophan are having 200 nm inner diameter and those from tyrosine are having the same around 50 nm diameter.

Polydiacetylene liposomes with phenylboronic acid tags: a fluorescence turn-on sensor for sialic acid detection and cell-surface glycan imaging.

PubMed

Wang, Dong-En; Yan, Jiahang; Jiang, Jingjing; Liu, Xiang; Tian, Chang; Xu, Juan; Yuan, Mao-Sen; Han, Xiang; Wang, Jinyi

2018-03-01

Sialic acid (SA) located at the terminal end of glycans on cell membranes has been shown to play an important yet distinctive role in various biological and pathological processes. Effective methods for the facile, sensitive and in situ analysis of SA on living cell surfaces are of great significance in terms of clinical diagnostics and therapeutics. Here, a new polydiacetylene (PDA) liposome-based sensor system bearing phenylboronic acid (PBA) and 1,8-naphthalimide derived fluorophore moieties was developed as a fluorescence turn-on sensor for the detection of free SA in aqueous solution and the in situ imaging of SA-terminated glycans on living cell surfaces. In the sensor system, three diacetylene monomers, PCDA-pBA, PCDA-Nap and PCDA-EA, were designed and synthesized to construct the composite PDA liposome sensor. The monomer PCDA-pBA modified with PBA molecules was employed as a receptor for SA recognition, while the monomer PCDA-Nap containing a 1,8-naphthalimide derivative fluorophore was used for fluorescence signaling. When the composite PDA liposomes were formed, the energy transfer between the fluorophore and the conjugated backbone could directly quench the fluorescence of the fluorophore. In the presence of additional SA or SA abundant cells, the strong binding of SA with PBA moieties disturbed the pendent side chain conformation, resulting in the fluorescence restoration of the fluorophore. The proposed methods realized the fluorescence turn-on detection of free SA in aqueous solution and the in situ imaging of SA on living MCF-7 cell surfaces. This work provides a new potential tool for simple and selective analysis of SA on living cell membranes.

Fluorescence diagnosis of tumor cells in hemangioblastoma cysts with 5-aminolevulinic acid.

PubMed

Utsuki, Satoshi; Oka, Hidehiro; Sato, Kimitoshi; Shimizu, Satoru; Suzuki, Sachio; Fujii, Kiyotaka

2010-01-01

Peritumoral hemangioblastoma cysts are usually composed of fibrous tissue without tumor cells. The authors describe the first case in which fluorescence with 5-aminolevulinic acid (5-ALA) was used to diagnose a hemangioblastoma tumor in a peritumoral cyst wall. A 27-year-old woman with a homogeneous, enhanced nodular lesion in the right hemisphere of the cerebellum underwent surgical treatment. After the nodular lesion was removed, the cyst region was observed with the aid of a semiconductor laser with a peak wavelength of 405 +/- 1 nm, which was powered using a fiberoptic cable. The cyst region was visualized with strong fluorescence, which disappeared after tissue removal. The fluorescent cyst consisted of tumor cells. The authors conclude that fluorescence diagnosis performed using 5-ALA can inform the choice of removing hemangioblastoma cysts.

"ICT-not-quenching" near infrared ratiometric fluorescent detection of picric acid in aqueous media.

PubMed

Xu, Yongqian; Li, Benhao; Li, Weiwei; Zhao, Jie; Sun, Shiguo; Pang, Yi

2013-05-25

The first "off-on" and ratiometric fluorescent method based on ICT mechanism for picric acid (PA) recognition in the near infrared region was constructed. Key advantages of the unique molecular architecture can fulfil the ratiometric response to electron-deficient featured PA which inclines to quench fluorescence of all reported sensors for PA.

Fabrication of highly fluorescent graphene quantum dots using L-glutamic acid for in vitro/in vivo imaging and sensing.

PubMed

Wu, Xu; Tian, Fei; Wang, Wenxue; Chen, Jiao; Wu, Min; Zhao, Julia Xiaojun

2013-08-21

A facile bottom-up method for the synthesis of highly fluorescent graphene quantum dots (GQDs) has been developed using a one-step pyrolysis of a natural amino acid, L-glutamic acid, with the assistance of a simple heating mantle device. The developed GQDs showed strong blue, green and red luminescence under the irradiation of ultra-violet, blue and green light, respectively. Moreover, the GQDs emitted near-infrared (NIR) fluorescence in the range of 800-850 nm with the excitation-dependent manner. This NIR fluorescence has a large Stokes shift of 455 nm, providing significant advantage for sensitive determination and imaging of biological targets. The fluorescence properties of the GQDs, such as quantum yields, fluorescence life time, and photostability, were measured and the fluorescence quantum yield was as high as 54.5 %. The morphology and composites of the GQDs were characterized using TEM, SEM, EDS, and FT-IR. The feasibility of using the GQDs as a fluorescent biomarker was investigated through in vitro and in vivo fluorescence imaging. The results showed that the GQDs could be a promising candidate for bioimaging. Most importantly, compared to the traditional quantum dots (QDs), the GQDs is chemically inert. Thus, the potential toxicity of the intrinsic heavy metal in the traditional QDs would not be a concern for GQDs. In addition, the GQDs possessed an intrinsic peroxidase-like catalytic activity that was similar to the graphene sheets and carbon nanotubes. Coupled with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), the GQDs can be used for the sensitive detection of hydrogen peroxide with a limit of detection of 20 μM.

Fabrication of highly fluorescent graphene quantum dots using L-glutamic acid for in vitro/in vivo imaging and sensing

PubMed Central

Wu, Xu; Tian, Fei; Wang, Wenxue; Chen, Jiao; Wu, Min; Zhao, Julia Xiaojun

2013-01-01

A facile bottom-up method for the synthesis of highly fluorescent graphene quantum dots (GQDs) has been developed using a one-step pyrolysis of a natural amino acid, L-glutamic acid, with the assistance of a simple heating mantle device. The developed GQDs showed strong blue, green and red luminescence under the irradiation of ultra-violet, blue and green light, respectively. Moreover, the GQDs emitted near-infrared (NIR) fluorescence in the range of 800–850 nm with the excitation-dependent manner. This NIR fluorescence has a large Stokes shift of 455 nm, providing significant advantage for sensitive determination and imaging of biological targets. The fluorescence properties of the GQDs, such as quantum yields, fluorescence life time, and photostability, were measured and the fluorescence quantum yield was as high as 54.5 %. The morphology and composites of the GQDs were characterized using TEM, SEM, EDS, and FT-IR. The feasibility of using the GQDs as a fluorescent biomarker was investigated through in vitro and in vivo fluorescence imaging. The results showed that the GQDs could be a promising candidate for bioimaging. Most importantly, compared to the traditional quantum dots (QDs), the GQDs is chemically inert. Thus, the potential toxicity of the intrinsic heavy metal in the traditional QDs would not be a concern for GQDs. In addition, the GQDs possessed an intrinsic peroxidase-like catalytic activity that was similar to the graphene sheets and carbon nanotubes. Coupled with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), the GQDs can be used for the sensitive detection of hydrogen peroxide with a limit of detection of 20 μM. PMID:23997934

Complexation induced fluorescence and acid-base properties of dapoxyl dye with γ-cyclodextrin: a drug-binding application using displacement assays.

PubMed

Pal, Kaushik; Mallick, Suman; Koner, Apurba L

2015-06-28

Host-guest complexation of dapoxyl sodium sulphonate (DSS), an intramolecular charge transfer dye with water-soluble and non-toxic macrocycle γ-cyclodextrin (γ-CD), has been investigated in a wide pH range. Steady-state absorption, fluorescence and time-resolved fluorescence measurements confirm the positioning of DSS into the hydrophobic cavity of γ-CD. A large fluorescence enhancement ca. 30 times, due to 1 : 2 complex formation and host-assisted guest-protonation have been utilised for developing a method for the utilisation of CD based drug-delivery applications. A simple fluorescence-displacement based approach is implemented at physiological pH for the assessment of binding strength of pharmaceutically useful small drug molecules (ibuprofen, paracetamol, methyl salicylate, salicylic acid, aspirin, and piroxicam) and six important antibiotic drugs (resazurin, thiamphenicol, chloramphenicol, ampicillin, kanamycin, and sorbic acid) with γ-CD.

Photodynamic diagnosis (PDD) of bladder cancer with intravesical 5-aminolevulinic-acid-induced fluorescence

NASA Astrophysics Data System (ADS)

Grimbergen, Matthijs C. M.; Jonges, T. G. N.; Lock, M. Tycho W.; van Swol, Christiaan F. P.; Boon, Tom A.; van Moorselaar, R. Jeroen A.

2001-05-01

Flat urothelial lesions as well as small papillary tumors are easily missed during transurethral resection (TUR). PDD is based on the detection of protoporphyrin-IX induced fluorescence after topical administration of 5- aminolevulinic acid (ALA). We report on our initial clinical results of 130 procedures in 98 patients. Two hours prior to TUR 1.5 g ALA dissolved in 50 ml 1.4% NaHCO3 solution was installed intravesically. For fluorescence excitation a blue light source (375-440 nm, Karl Storz) was used. In total 478 biopsies (2-9 per patient) were taken from fluorescent and nonfluorescent areas. Normal nonfluorescent bladder urothelium was blue, whereas cancer epithelium developed a brilliant red fluorescence. During white light cystoscopy, 143 bladder tumors were found. Sixty-three additional tumors were detected because of their positive fluorescence. The overall sensitivity of fluorescence cystoscopy (98%) was greater than that of white light cystoscopy (69%). Their specificities were 51% and 80% respectively.

Far-red fluorescent probes for canonical and non-canonical nucleic acid structures: current progress and future implications.

PubMed

Suseela, Y V; Narayanaswamy, Nagarjun; Pratihar, Sumon; Govindaraju, Thimmaiah

2018-02-05

The structural diversity and functional relevance of nucleic acids (NAs), mainly deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are indispensable for almost all living organisms, with minute aberrations in their structure and function becoming causative factors in numerous human diseases. The standard structures of NAs, termed canonical structures, are supported by Watson-Crick hydrogen bonding. Under special physiological conditions, NAs adopt distinct spatial organisations, giving rise to non-canonical conformations supported by hydrogen bonding other than the Watson-Crick type; such non-canonical structures have a definite function in controlling gene expression and are considered as novel diagnostic and therapeutic targets. Development of molecular probes for these canonical and non-canonical DNA/RNA structures has been an active field of research. Among the numerous probes studied, probes with turn-on fluorescence in the far-red (600-750 nm) region are highly sought-after due to minimal autofluorescence and cellular damage. Far-red fluorescent probes are vital for real-time imaging of NAs in live cells as they provide good resolution and minimal perturbation of the cell under investigation. In this review, we present recent advances in the area of far-red fluorescent probes of DNA/RNA and non-canonical G-quadruplex structures. For the sake of continuity and completeness, we provide a brief overview of visible fluorescent probes. Utmost importance is given to design criteria, characteristic properties and biological applications, including in cellulo imaging, apart from critical discussion on limitations of the far-red fluorescent probes. Finally, we offer current and future prospects in targeting canonical and non-canonical NAs specific to cellular organelles, through sequence- and conformation-specific far-red fluorescent probes. We also cover their implications in chemical and molecular biology, with particular focus on decoding various disease

Non-destructive Determination of Shikimic Acid Concentration in Transgenic Maize Exhibiting Glyphosate Tolerance Using Chlorophyll Fluorescence and Hyperspectral Imaging

PubMed Central

Feng, Xuping; Yu, Chenliang; Chen, Yue; Peng, Jiyun; Ye, Lanhan; Shen, Tingting; Wen, Haiyong; He, Yong

2018-01-01

The development of transgenic glyphosate-tolerant crops has revolutionized weed control in crops in many regions of the world. The early, non-destructive identification of superior plant phenotypes is an important stage in plant breeding programs. Here, glyphosate-tolerant transgenic maize and its parental wild-type control were studied at 2, 4, 6, and 8 days after glyphosate treatment. Visible and near-infrared hyperspectral imaging and chlorophyll fluorescence imaging techniques were applied to monitor the performance of plants. In our research, transgenic maize, which was highly tolerant to glyphosate, was phenotyped using these high-throughput non-destructive methods to validate low levels of shikimic acid accumulation and high photochemical efficiency of photosystem II as reflected by maximum quantum yield and non-photochemical quenching in response to glyphosate. For hyperspectral imaging analysis, the combination of spectroscopy and chemometric methods was used to predict shikimic acid concentration. Our results indicated that a partial least-squares regression model, built on optimal wavelengths, effectively predicted shikimic acid concentrations, with a coefficient of determination value of 0.79 for the calibration set, and 0.82 for the prediction set. Moreover, shikimic acid concentration estimates from hyperspectral images were visualized on the prediction maps by spectral features, which could help in developing a simple multispectral imaging instrument for non-destructive phenotyping. Specific physiological effects of glyphosate affected the photochemical processes of maize, which induced substantial changes in chlorophyll fluorescence characteristics. A new data-driven method, combining mean fluorescence parameters and featuring a screening approach, provided a satisfactory relationship between fluorescence parameters and shikimic acid content. The glyphosate-tolerant transgenic plants can be identified with the developed discrimination model

Non-destructive Determination of Shikimic Acid Concentration in Transgenic Maize Exhibiting Glyphosate Tolerance Using Chlorophyll Fluorescence and Hyperspectral Imaging.

PubMed

Feng, Xuping; Yu, Chenliang; Chen, Yue; Peng, Jiyun; Ye, Lanhan; Shen, Tingting; Wen, Haiyong; He, Yong

2018-01-01

The development of transgenic glyphosate-tolerant crops has revolutionized weed control in crops in many regions of the world. The early, non-destructive identification of superior plant phenotypes is an important stage in plant breeding programs. Here, glyphosate-tolerant transgenic maize and its parental wild-type control were studied at 2, 4, 6, and 8 days after glyphosate treatment. Visible and near-infrared hyperspectral imaging and chlorophyll fluorescence imaging techniques were applied to monitor the performance of plants. In our research, transgenic maize, which was highly tolerant to glyphosate, was phenotyped using these high-throughput non-destructive methods to validate low levels of shikimic acid accumulation and high photochemical efficiency of photosystem II as reflected by maximum quantum yield and non-photochemical quenching in response to glyphosate. For hyperspectral imaging analysis, the combination of spectroscopy and chemometric methods was used to predict shikimic acid concentration. Our results indicated that a partial least-squares regression model, built on optimal wavelengths, effectively predicted shikimic acid concentrations, with a coefficient of determination value of 0.79 for the calibration set, and 0.82 for the prediction set. Moreover, shikimic acid concentration estimates from hyperspectral images were visualized on the prediction maps by spectral features, which could help in developing a simple multispectral imaging instrument for non-destructive phenotyping. Specific physiological effects of glyphosate affected the photochemical processes of maize, which induced substantial changes in chlorophyll fluorescence characteristics. A new data-driven method, combining mean fluorescence parameters and featuring a screening approach, provided a satisfactory relationship between fluorescence parameters and shikimic acid content. The glyphosate-tolerant transgenic plants can be identified with the developed discrimination model

Fluorescence analysis of humic and fulvic acids from two Brazilian oxisols as affected by biosolid amendment.

PubMed

Bertoncini, E I; D'Orazio, V; Senesi, N; Mattiazzo, M E

2005-03-01

Conventional monodimensional fluorescence spectroscopy in the emission, excitation, and synchronous-scan modes and total luminescence spectroscopy have proven to be sensitive techniques for characterization and differentiation of humic acid (HA) and fulvic acid (FA) fractions isolated from an aerobically and anaerobically digested and limed biosolid, two layers of a sandy and a clayey Brazilian oxisol, and the corresponding biosolid-amended soils. The spectral patterns and the relative fluorescence intensities suggest greater molecular heterogeneity, less aromatic polycondensation, and less humification of biosolid HA and FA compared with soil HA and FA. However, the differences are smaller for the FA fractions than for the HA fractions. Fluorescence properties of soil HA and FA differ slightly as a function of soil type and soil layer. Biosolid application causes a shift to shorter wavelengths of the main fluorescence peaks and marked variation of the relative fluorescence intensities of HA and FA isolated from amended soils. These results suggest that molecular components of relatively small molecular size, with a low level of aromatic polycondensation, and low degree of humification present in biosolid HA and FA are partially and variously incorporated into amended soil HA and FA. In general, these modifications seem to be smaller in HA and FA from the clayey soil layers than in those from the sandy soil layers, possibly because of protective effects exerted by clay minerals of native soil HA and FA against disturbances caused by biosolid application.

Probing thermal stability of the β-lactoglobulin-oleic acid complex by fluorescence spectroscopy and molecular modeling

NASA Astrophysics Data System (ADS)

Simion (Ciuciu), Ana-Maria; Aprodu, Iuliana; Dumitrașcu, Loredana; Bahrim, Gabriela Elena; Alexe, Petru; Stănciuc, Nicoleta

2015-09-01

Bovine β-lactoglobulin is able to interact with different bioactive compounds, thus being an important candidate in the development of delivery systems with improved functionality. The heat induced changes in the β-lactoglobulin-oleic acid complex were examined by means of fluorescence spectroscopy and molecular modeling techniques. Fluorescence spectroscopy results indicated a rigid protein structure in the temperature range 25-70 °C, whereas at temperatures over 75 °C, the rearrangements of the polypeptide chains led to higher exposure of hydrophobic residues. The most significant increase of the accessible surface area with temperature increase was identified in case of Tyr99 and Tyr102. The phase diagram method indicated an all or none transition between two conformations. Due to conformational changes, no contact between Ile56 or Lys60 and the fatty acid could be identified at 85 °C, but new non-bonding interaction were established with Ile12 and Val15. The results obtained in this study provide important details about thermal induced changes in the conformation of β-lactoglobulin-oleic acid complex. Significant conformational changes were registered above 75 °C, suggesting the possibility of obtaining highly functional complexes between whey proteins and natural unsaturated fatty acids.

Complex-formation-enhanced fluorescence quenching effect for efficient detection of picric acid.

PubMed

Ding, Aixiang; Yang, Longmei; Zhang, Yuyang; Zhang, Gaobin; Kong, Lin; Zhang, Xuanjun; Tian, Yupeng; Tao, Xutang; Yang, Jiaxiang

2014-09-15

Amine-functionalized α-cyanostilbene derivatives (Z)-2-(4-aminophenyl)-3-(4-butoxyphenyl)acrylonitrile (ABA) and (Z)-3-(4-butoxyphenyl)-2-[4-(butylamino)phenyl]acrylonitrile (BBA) were designed for specific recognition of picric acid (PA), an environmental and biological pollutant. The 1:1 host-guest complexes formed between the chemosensors and PA enhanced fluorescence quenching, thus leading to sensitive and selective detection in aqueous media and the solid phase. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxygen-dependent delayed fluorescence measured in skin after topical application of 5-aminolevulinic acid.

PubMed

Harms, Floor A; de Boon, Wadim M I; Balestra, Gianmarco M; Bodmer, Sander I A; Johannes, Tanja; Stolker, Robert J; Mik, Egbert G

2011-10-01

Mitochondrial oxygen tension can be measured in vivo by means of oxygen-dependent quenching of delayed fluorescence of protoporphyrin IX (PpIX). Here we demonstrate that delayed fluorescence is readily observed from skin in rat and man after topical application of the PpIX precursor 5-aminolevulinic acid (ALA). Delayed fluorescence lifetimes respond to changes in inspired oxygen fraction and blood supply. The signals contain lifetime distributions and the fitting of rectangular distributions to the data appears more adequate than mono-exponential fitting. The use of topically applied ALA for delayed fluorescence lifetime measurements might pave the way for clinical use of this technique. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel fluorescence biosensor for sensitivity detection of tyrosinase and acid phosphatase based on nitrogen-doped graphene quantum dots.

PubMed

Qu, Zhengyi; Na, Weidan; Liu, Xiaotong; Liu, Hua; Su, Xingguang

2018-01-02

In this paper, we developed a sensitive fluorescence biosensor for tyrosinase (TYR) and acid phosphatase (ACP) activity detection based on nitrogen-doped graphene quantum dots (N-GQDs). Tyrosine could be catalyzed by TYR to generate dopaquinone, which could efficiently quench the fluorescence of N-GQDs, and the degree of fluorescence quenching of N-GQDs was proportional to the concentration of TYR. In the presence of ACP, l-Ascorbic acid-2-phosphate (AAP) was hydrolyzed to generate ascorbic acid (AA), and dopaquinone was reduced to l-dopa, resulting in the fluorescence recovery of the quenched fluorescence by dopaquinone. Thus, a novel fluorescence biosensor for the detection of TYR and ACP activity based on N-GQDs was constructed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of TYR and ACP in the range of 0.43-3.85 U mL -1 and 0.04-0.7 mU mL -1 with a detection limit of 0.15 U mL -1 and 0.014 mU mL -1 , respectively. The feasibility of the proposed biosensor in real samples assay was also studied and satisfactory results were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

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

Cao, X. T.; Showkat, A. M.; Wang, Z.

2015-03-30

Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrenemore » grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.« less

Simultaneous determination of Magnolol and Honokiol by amino acid ionic liquid synchronous fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Liu, Wei; Zhu, Xiashi

2018-05-01

A novel method based on amino acid ionic liquids (AAILs) as an additive synchronous fluorescence spectrometry is proposed for simultaneous determination of magnolol (MN) and honokiol (HN) in traditional Chinese medicine Houpu. The overlapping fluorescence spectrum of MN and HN could be completely separated in the AAILs medium. Experiment parameters (the type and concentration of AAILs, pH values and temperature) were discussed. The detection limits of MN and HN reached 1.46 ng/mL, 0.92 ng/mL and the recovery rates ranged from 98.6%-100.7%, 99.7%-100.6%, respectively. This methods was successfully employed for simultaneously determination of MN and HN in real samples. No significant differences could be found in the results of this method and the pharmacopoeia of People's Republic of China 2015 (Ch.P.2015). The experiment mechanisms were discussed by the Gaussian simulation and fluorescence quantum yield.

Acid-Activatable Michael-Type Fluorescent Probes for Thiols and for Labeling Lysosomes in Live Cells.

PubMed

Dai, Chun-Guang; Du, Xiao-Jiao; Song, Qin-Hua

2015-12-18

A Michael addition is usually taken as a base-catalyzed reaction. Most fluorescent probes have been designed to detect thiols in slightly alkaline solutions (pH 7-9). The sensing reactions of almost all Michael-type fluorescent probes for thiols are faster in a high pH solution than in a low pH solution. In this work, we synthesized a series of 7-substituted 2-(quinolin-2-ylmethylene)malonic acids (QMAs, substituents: NEt2, OH, H, Cl, or NO2) and their ethyl esters (QMEs) as Michael-type fluorescent probes for thiols. The sensing reactions of QMAs and QMEs occur in distinct pH ranges, pH < 7 for QMAs and pH > 7 for QMEs. On the basis of experimental and theoretic studies, we have clarified the distinct pH effects on the sensing reactivity between QMAs and QMEs and demonstrated that two QMAs (NEt2, OH) are highly sensitive and selective fluorescent probes for thiols in acidic solutions (pH < 7) and promising dyes that can label lysosomes in live cells.

Characterization of interaction between amino acids and fulvic-like organic matter by fluorescence spectroscopy combining thermodynamic calculation.

PubMed

Lin, Tao; Hou, Bingwei; Wang, Jian; Xu, Yaqun; Chen, Wei

2017-03-01

Dissolved organic matter (DOM), as a very fine colloidal suspension, could inevitably affect the transformation process of dissolved organic nitrogen (DON) in drinking water treatment. Tryptophan and tyrosine were used as representatives of DON to investigate the interactions between amino acids and fulvic-like components of fluorescent DOM using titration experiments. The fluorescence intensity decreased significantly with the increasing fulvic acid (FA) concentration, suggesting that FA could greatly quench the intrinsic fluorescence of amino acids such as tryptophan and tyrosine. The absolute spectrum peaks of amino acids (AA) were changed in the presence of FA, possibly being resulted from non-covalent interactions between amino acids and FA. The specific hydrogen bonding and van der Waals forces played dominant roles in the interactions according to the results of theoretical analysis and thermodynamic calculation. The distance between donor and acceptor was 1.25 and 1.14 nm for the FA-tyrosine and FA-tryptophan system, indicating the energy transfer from tyrosine or tryptophan to FA. The association constant (K) decreased with the increase of temperature and pH value, while the change of ionic strength had no obvious influence on K value.

5-Aminolevulinic acid-induced protoporphyrin IX fluorescence in meningioma: qualitative and quantitative measurements in vivo.

PubMed

Valdes, Pablo A; Bekelis, Kimon; Harris, Brent T; Wilson, Brian C; Leblond, Frederic; Kim, Anthony; Simmons, Nathan E; Erkmen, Kadir; Paulsen, Keith D; Roberts, David W

2014-03-01

The use of 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) fluorescence has shown promise as a surgical adjunct for maximizing the extent of surgical resection in gliomas. To date, the clinical utility of 5-ALA in meningiomas is not fully understood, with most descriptive studies using qualitative approaches to 5-ALA-PpIX. To assess the diagnostic performance of 5-ALA-PpIX fluorescence during surgical resection of meningioma. ALA was administered to 15 patients with meningioma undergoing PpIX fluorescence-guided surgery at our institution. At various points during the procedure, the surgeon performed qualitative, visual assessments of fluorescence by using the surgical microscope, followed by a quantitative fluorescence measurement by using an intraoperative probe. Specimens were collected at each point for subsequent neuropathological analysis. Clustered data analysis of variance was used to ascertain a difference between groups, and receiver operating characteristic analyses were performed to assess diagnostic capabilities. Red-pink fluorescence was observed in 80% (12/15) of patients, with visible fluorescence generally demonstrating a strong, homogenous character. Quantitative fluorescence measured diagnostically significant PpIX concentrations (cPpIx) in both visibly and nonvisibly fluorescent tissues, with significantly higher cPpIx in both visibly fluorescent (P < .001) and tumor tissue (P = .002). Receiver operating characteristic analyses also showed diagnostic accuracies up to 90% for differentiating tumor from normal dura. ALA-induced PpIX fluorescence guidance is a potential and promising adjunct in accurately detecting neoplastic tissue during meningioma resective surgery. These results suggest a broader reach for PpIX as a biomarker for meningiomas than was previously noted in the literature.

5-Aminolevulinic Acid-Induced Protoporphyrin IX Fluorescence in Meningioma: Qualitative and Quantitative Measurements In Vivo

PubMed Central

Valdes, Pablo A.; Bekelis, Kimon; Harris, Brent T.; Wilson, Brian C.; Leblond, Frederic; Kim, Anthony; Simmons, Nathan E.; Erkmen, Kadir; Paulsen, Keith D.; Roberts, David W.

2014-01-01

BACKGROUND The use of 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) fluorescence has shown promise as a surgical adjunct for maximizing the extent of surgical resection in gliomas. To date, the clinical utility of 5-ALA in meningiomas is not fully understood, with most descriptive studies using qualitative approaches to 5-ALA-PpIX. OBJECTIVE To assess the diagnostic performance of 5-ALA-PpIX fluorescence during surgical resection of meningioma. METHODS ALA was administered to 15 patients with meningioma undergoing PpIX fluorescence-guided surgery at our institution. At various points during the procedure, the surgeon performed qualitative, visual assessments of fluorescence by using the surgical microscope, followed by a quantitative fluorescence measurement by using an intra-operative probe. Specimens were collected at each point for subsequent neuropathological analysis. Clustered data analysis of variance was used to ascertain a difference between groups, and receiver operating characteristic analyses were performed to assess diagnostic capabilities. RESULTS Red-pink fluorescence was observed in 80% (12/15) of patients, with visible fluorescence generally demonstrating a strong, homogenous character. Quantitative fluorescence measured diagnostically significant PpIX concentrations (CPpIx) in both visibly and nonvisibly fluorescent tissues, with significantly higher CPpIx in both visibly fluorescent (P < .001) and tumor tissue (P = .002). Receiver operating characteristic analyses also showed diagnostic accuracies up to 90% for differentiating tumor from normal dura. CONCLUSION ALA-induced PpIX fluorescence guidance is a potential and promising adjunct in accurately detecting neoplastic tissue during meningioma resective surgery. These results suggest a broader reach for PpIX as a biomarker for meningiomas than was previously noted in the literature. PMID:23887194

Binding effect of fluorescence labeled glycyrrhetinic acid with GA receptors in hepatocellular carcinoma cells.

PubMed

Sun, Yu-Qi; Dai, Chun-Mei; Zheng, Yan; Shi, Shu-Dan; Hu, Hai-Yang; Chen, Da-Wei

2017-11-01

Glycyrrhetinic acid (GA) is a natural active component from licorice, which is broadly used in traditional Chinese medicine. Lots of glycyrrhetinic acid receptors (GA-R) are proved to locate on the surface of liver cells. Many reports about the hepatocellular carcinoma (HCC) treatment were dependent on GA modified carriers. However, the reality of GA-R in HCC cells was not clear. In this paper, 18β-glycyrrhetinic acid (18β-GA) was labeled with fluorescence (FITC) by chemical synthesis. Together with the binding effect of fluorescence labeled glycyrrhetinic acid (FITC-GA), the competitive action of 18β-GA with GA-R was investigated in HCC cells. The results showed that in HepG2 cells, 18β-GA and FITC-GA presented similar cytotoxicity. The specific binding saturation of GA showed the dissociation constant (K d ) was 7.457±2.122pmol/L and the maximum binding counts (B max ) was 2.385±0.175pmol/2.5×10 6 cells, respectively. FITC-GA bound to cytomembrane specifically and 18β-GA competed to bind the sites significantly in HepG2 cells. Therefore, there is binding effect between fluorescence labeled GA and GA-R. The GA-R on HCC cells is confirmed as expected, which provides a useful reference of active target modified by GA and a novel approach for receptors and ligands study. Copyright © 2017 Elsevier Inc. All rights reserved.

An off-on fluorescence probe targeting mitochondria based on oxidation-reduction response for tumor cell and tissue imaging

NASA Astrophysics Data System (ADS)

Yao, Hanchun; Cao, Li; Zhao, Weiwei; Zhang, Suge; Zeng, Man; Du, Bin

2017-10-01

In this study, a tumor-targeting poly( d, l-lactic-co-glycolic acid) (PLGA) loaded "off-on" fluorescent probe nanoparticle (PFN) delivery system was developed to evaluate the region of tumor by off-on fluorescence. The biodegradability of the nanosize PFN delivery system readily released the probe under tumor acidic conditions. The probe with good biocompatibility was used to monitor the intracellular glutathione (GSH) of cancer cells and selectively localize to mitochondria for tumor imaging. The incorporated tumor-targeting probe was based on the molecular photoinduced electron transfer (PET) mechanism preventing fluorescence ("off" state) and could be easily released under tumor acidic conditions. However, the released tumor-targeting fluorescence probe molecule was selective towards GSH with high selectivity and an ultra-sensitivity for the mitochondria of cancer cells and tissues significantly increasing the probe molecule fluorescence signal ("on" state). The tumor-targeting fluorescence probe showed sensitivity to GSH avoiding interference from cysteine and homocysteine. The PFNs could enable fluorescence-guided cancer imaging during cancer therapy. This work may expand the biological applications of PFNs as a diagnostic reagent, which will be beneficial for fundamental research in tumor imaging. [Figure not available: see fulltext.

Tumor acidity-activatable TAT targeted nanomedicine for enlarged fluorescence/magnetic resonance imaging-guided photodynamic therapy.

PubMed

Gao, Meng; Fan, Feng; Li, Dongdong; Yu, Yue; Mao, Kuirong; Sun, Tianmeng; Qian, Haisheng; Tao, Wei; Yang, Xianzhu

2017-07-01

Nanoparticles simultaneously integrated the photosensitizers and diagnostic agents represent an emerging approach for imaging-guided photodynamic therapy (PDT). However, the diagnostic sensitivity and therapeutic efficacy of nanoparticles as well as the heterogeneity of tumors pose tremendous challenges for clinical imaging-guided PDT treatment. Herein, a polymeric nanoparticle with tumor acidity (pH e )-activatable TAT targeting ligand that encapsulates the photosensitizer chlorin e6 (Ce6) and chelates contrast agent Gd 3+ is successfully developed for fluorescence/magnetic resonance (MR) dual-model imaging-guided precision PDT. We show clear evidence that the resulting nanoparticle DA TAT-NP [its TAT lysine residues' amines was modified by 2,3-dimethylmaleic anhydride (DA)] efficiently avoids the rapid clearance by reticuloendothelial system (RES) by masking of the TAT peptide, resulting in the significantly prolonged circulation time in the blood. Once accumulating in the tumor tissues, DA TAT-NP is reactivated by tumor acidity to promote cellular uptake, resulting in enlarged fluorescence/MR imaging signal intensity and elevated in vivo PDT therapeutic effect. This concept provides new avenues to design tumor acidity-activatable targeted nanoparticles for imaging-guided cancer therapy. Copyright © 2017 Elsevier Ltd. All rights reserved.

An erythrosin B-based "turn on" fluorescent sensor for detecting perfluorooctane sulfonate and perfluorooctanoic acid in environmental water samples.

PubMed

Cheng, Zhen; Du, Lingling; Zhu, Panpan; Chen, Qian; Tan, Kejun

2018-05-04

Because of the serious harm to animals and the environment associated with perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), a rapid, sensitive and low-cost method for detecting PFOS and PFOA is of great importance. In this paper, a novel sensing method has been proposed for the highly sensitive detection of PFOS and PFOA in environmental water samples based on the "turn-on" switch of erythrosine B (EB)-hexadecyltrimethylammonium bromide (CTAB) system. In pH 8.55 Britton-Robinson (BR) buffer, EB can react with CTAB by electrostatic attraction, resulting in a strong fluorescence quenching of EB. With a subsequent addition of the CTAB, a red-shift occurred (11 nm), followed by a significant increase in fluorescence at high surfactant concentrations. It was found that PFOS and PFOA can obviously enhance fluorescence intensity of EB-CTAB system. The enhanced fluorescence intensity is proportional to the concentration of PFOS and PFOA in the range of 0.05-10 μM with detection limit of 12.8 nM and 11.8 nM (3σ), respectively. The presented assay has been successfully applied to sensing PFOS and PFOA in real water samples with RSD ≤ 4.3% and 2.9%, respectively. Copyright © 2018 Elsevier B.V. All rights reserved.

Dynamics of internal pore opening in KV channels probed by a fluorescent unnatural amino acid

PubMed Central

Kalstrup, Tanja; Blunck, Rikard

2013-01-01

Atomic-scale models on the gating mechanism of voltage-gated potassium channels (Kv) are based on linear interpolations between static structures of their initial and final state derived from crystallography and molecular dynamics simulations, and, thus, lack dynamic structural information. The lack of information on dynamics and intermediate states makes it difficult to associate the structural with the dynamic functional data obtained with electrophysiology. Although voltage-clamp fluorometry fills this gap, it is limited to sites extracellularly accessible, when the key region for gating is located at the cytosolic side of the channels. Here, we solved this problem by performing voltage-clamp fluorometry with a fluorescent unnatural amino acid. By using an orthogonal tRNA-synthetase pair, the fluorescent unnatural amino acid was incorporated in the Shaker voltage-gated potassium channel at key regions that were previously inaccessible. Thus, we defined which parts act independently and which parts act cooperatively and found pore opening to occur in two sequential transitions. PMID:23630265

Fluorescent carbon nanodots for sensitive and selective detection of tannic acid in wines.

PubMed

Ahmed, Gaber Hashem Gaber; Laíño, Rosana Badía; Calzón, Josefa Angela García; García, Marta Elena Díaz

2015-01-01

Herein we describe an easy one step synthesis of carbon nanodots (C-dots) by thermal carbonization of 6-bromohexylboronic acid using two different amine compounds, polyethyleneglycol bis(3-aminopropyl (PEGA) and 1,2-aminopropane (DPA), at 180 °C in atmospheric oxygen. The as-synthesized C-dots were characterized by FTIR, HRTEM, NMR and fluorescence. The C-dots prepared using PEGA showed a strong emission at 440 nm with excitation at 362 nm. These C-dots exhibited analytical potential as sensing probes for tannic acid (TA) determination. pH effect, interferences, and analytical performance of the method were investigated. The method was found effective in the linear concentration range from 0.1 to 10 mg L(-1) TA achieving a limit of detection equal 0.018 mg L(-1) TA. The applicability of the method was demonstrated by direct measurements of TA in red and white wine samples. Validation of the method was achieved by spiking the wine samples with different standard TA concentrations obtaining recoveries in the range (90-112.5%). A probable mechanism by which TA quenched the C-dots fluorescence was proposed. Copyright © 2014 Elsevier B.V. All rights reserved.

Charge-transfer-based terbium MOF nanoparticles as fluorescent pH sensor for extreme acidity.

PubMed

Qi, Zewan; Chen, Yang

2017-01-15

Newly emerged metal organic frameworks (MOFs) have aroused the great interest in designing functional materials by means of its flexible structure and component. In this study, we used lanthanide Tb 3+ ions and small molecular ligands to design and assemble a kind of pH-sensitive MOF nanoparticle based on intramolecular-charge-transfer effect. This kind of made-to-order MOF nanoparticle for H + is highly specific and sensitive and could be used to fluorescently indicate pH value of strong acidic solution via preset mechanism through luminescence of Tb 3+ . The long luminescence lifetime of Tb 3+ allows eliminating concomitant non-specific fluorescence by time-revised fluorescence techniques, processing an advantage in sensing H + in biological media with strong autofluorescence. Our method showed a great potential of MOF structures in designing and constructing sensitive sensing materials for specific analytes directly via the assembly of functional ions/ligands. Copyright © 2016 Elsevier B.V. All rights reserved.

Fluorescence Stability of Mercaptopropionic Acid Capped Cadmium Telluride Quantum Dots in Various Biochemical Buffers.

PubMed

Borse, Vivek; Kashikar, Adisha; Srivastava, Rohit

2018-04-01

Quantum dots are the semiconductor nanocrystals having unique optical and electronic properties. Quantum dots are category of fluorescent labels utilized for biological tagging, biosensing, bioassays, bioimaging and in vivo imaging as they exhibit very small size, signal brightness, photostability, tuning of light emission range, longer photoluminescence decay time as compared to organic dyes. In this work, we have synthesized and characterized mercaptopropionic acid capped cadmium telluride quantum dots (MPA-CdTe QDs) using hydrothermal method. The study further reports fluorescence intensity stability of quantum dots suspended in different buffers of varying concentration (1-100 mM), stored at various photophysical conditions. Fluorescence intensity values were reduced with increase in buffer concentration. When the samples were stored at room temperature in ambient light condition the quantum dots suspended in different buffers lost the fluorescence intensity after day 15 (except TRIS II). Fluorescence intensity values were found stable for more than 30 days when the samples were stored in dark condition. Samples stored in refrigerator displayed modest fluorescence intensity even after 300 days of storage. Thus, storage of MPA-CdTe QDs in refrigerator may be the suitable choice to maintain its fluorescence stability for longer time for further application.

Formation of aldehydes and carboxylic acids in ozonated surface water and wastewater: a clear relationship with fluorescence changes.

PubMed

Liu, Chen; Tang, Xiangyu; Kim, Jaeshin; Korshin, Gregory V

2015-04-01

This study examined the formation of aldehydes and carboxylic acids in ozonated surface water and municipal wastewater secondary effluent and addressed correlations between the generation of these compounds and concurrent changes of the fluorescence of natural/effluent organic matter (NOM/EfOM) substrates. Ozonation was effective in removing fluorophores in all excitation/emission matrix (EEM) regions, with those operationally assigned to humic- and protein-like species showing relatively higher reactivity than fulvic-like species. Examination of HO exposures and attendant changes of fluorescence-based parameters allows establishing strong linear relationships between formation of the aldehydes and carboxylic acids and the relative changes of integrated fluorescence (ΔIF/IF0). This demonstrates the feasibility of surrogate monitoring of the formation of biodegradable ozonation by-products via online measurements of water/wastewater EEM fluorescence. Copyright © 2014 Elsevier Ltd. All rights reserved.

Scanning Fiber Endoscope Improves Detection of 5-Aminolevulinic Acid-Induced Protoporphyrin IX Fluorescence at the Boundary of Infiltrative Glioma.

PubMed

Belykh, Evgenii; Miller, Eric J; Hu, Danying; Martirosyan, Nikolay L; Woolf, Eric C; Scheck, Adrienne C; Byvaltsev, Vadim A; Nakaji, Peter; Nelson, Leonard Y; Seibel, Eric J; Preul, Mark C

2018-05-01

Fluorescence-guided surgery with protoporphyrin IX (PpIX) as a photodiagnostic marker is gaining acceptance for resection of malignant gliomas. Current wide-field imaging technologies do not have sufficient sensitivity to detect low PpIX concentrations. We evaluated a scanning fiber endoscope (SFE) for detection of PpIX fluorescence in gliomas and compared it to an operating microscope (OPMI) equipped with a fluorescence module and to a benchtop confocal laser scanning microscope (CLSM). 5-Aminolevulinic acid-induced PpIX fluorescence was assessed in GL261-Luc2 cells in vitro and in vivo after implantation in mouse brains, at an invading glioma growth stage, simulating residual tumor. Intraoperative fluorescence of high and low PpIX concentrations in normal brain and tumor regions with SFE, OPMI, CLSM, and histopathology were compared. SFE imaging of PpIX correlated to CLSM at the cellular level. PpIX accumulated in normal brain cells but significantly less than in glioma cells. SFE was more sensitive to accumulated PpIX in fluorescent brain areas than OPMI (P < 0.01) and dramatically increased imaging time (>6×) before tumor-to-background contrast was diminished because of photobleaching. SFE provides new endoscopic capabilities to view PpIX-fluorescing tumor regions at cellular resolution. SFE may allow accurate imaging of 5-aminolevulinic acid labeling of gliomas and other tumor types when current detection techniques have failed to provide reliable visualization. SFE was significantly more sensitive than OPMI to low PpIX concentrations, which is relevant to identifying the leading edge or metastasizing cells of malignant glioma or to treating low-grade gliomas. This new application has the potential to benefit surgical outcomes. Copyright © 2018 Elsevier Inc. All rights reserved.

[Effects of simulated acid rain on Quercus glauca seedlings photosynthesis and chlorophyll fluorescence].

PubMed

Li, Jia; Jiang, Hong; Yu, Shu-quan; Jiang, Fu-wei; Yin, Xiu-min; Lu, Mei-juan

2009-09-01

Taking the seedlings of Quercus glauca, a dominant evergreen broadleaf tree species in subtropical area, as test materials, this paper studied their photosynthesis, chlorophyll fluorescence, and chlorophyll content under effects of simulated acid rain with pH 2.5, 4.0, and 5.6 (CK). After 2-year acid rain stress, the net photosynthetic rate of Q. glauca increased significantly with decreasing pH of acid rain. The acid rain with pH 2.5 and 4.0 increased the stomatal conductance and transpiration rate, and the effect was more significant under pH 2.5. The intercellular CO2 concentration decreased in the order of pH 2.5 > pH 5.6 > pH 4.0. The maximum photosynthetic rate, light compensation point, light saturation point, and dark respiration rate were significantly higher under pH 2.5 and 4.0 than under pH 5.6, while the apparent quantum yield was not sensitive to acid rain stress. The maximal photochemical efficiency of PS II and the potential activity of PS II under pH 2.5 and 4.0 were significantly higher than those under pH 5.6. The relative chlorophyll content was in the order of pH 2.5 > pH 5.6 > pH 4.0, and there was a significant difference between pH 2.5 and 4.0. All the results suggested that the photosynthesis and chlorophyll fluorescence of Q. glauca increased under the effects of acid rain with pH 2.5 and 4.0, and the acid rain with pH 2.5 had more obvious effects.

A Novel method for the preparation of fluorescent C60 poly(amino acid) composites and their biological imaging.

PubMed

Xu, Dazhuang; Liu, Meiying; Huang, Qiang; Chen, Junyu; Huang, Hongye; Deng, Fengjie; Tian, Jianwen; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

2018-04-15

Recently, fullerene (C 60 ) and its derivatives have been widely explored for many applications owing to their enriched physical and chemical properties. Specifically, the synthesis and biomedical applications of fluorescent C 60 have been extensively investigated previously. However, the preparation of polymer-functionalized fluorescent C 60 has not been reported thus far. In this study, water-dispersible fluorescent C 60 polymer composites were successfully synthesized through the combination of the thiol-ene click reaction and subsequent ring-opening polymerization. First, 2-aminoethanethiol was introduced on the surface of C 60 by the thiol-ene click reaction. The surface of amino group-functionalized C 60 (C 60 -NH 2 ) was further modified with poly(amino acid)s via ring-open polymerization of GluEG N-carboxyanhydrides (NCAs). The morphology, functional groups, optical properties and biocompatibility were examined by a number of characterization equipment and assays in detail. We demonstrated that the resultant fluorescent C 60 poly(amino acid) (C 60 -GluEG) composites have a small size (about 5 nm), high water dispersibility, intense fluorescence and high photostability. Cell viability results implied that the C 60 -GluEG composites possess low cytotoxicity. Moreover, these C 60 -GluEG composites can easily penetrate into live cells, indicating their great potential for biological imaging applications. Copyright © 2018 Elsevier Inc. All rights reserved.

A fluorescent microplate assay for diarrheic shellfish toxins.

PubMed

Vieytes, M R; Fontal, O I; Leira, F; Baptista de Sousa, J M; Botana, L M

1997-06-01

A fluorescent enzyme inhibition assay for okadaic acid using 4-methylumbelliferyl phosphate and fluorescein diphosphate as substrates for the enzyme phosphatase 2A was developed. In the inhibition assay, performed in a microtiter plate, the PP2A was inhibited by adding okadaic acid and the resulting fluorescence enhancement derived from enzymatic hydrolysis of the substrate was quantified in a fluorescence plate reader. The measurable range of okadaic acid was 3.2 to 3200 pg/ml with an IC50 = 0.1 nM. The detection limit of okadaic acid was 2.56 pg/well in buffer solutions and 12.8 ng/g hepatopancreas in shellfish extracts. The coefficient of variation (CV, n = 22) for each point ranged from 18.80 to 37.90% (mean 28.35%). The proposed method is very convenient, rapid, and sensitive by using the enzyme inhibition assay system and fluorescent reaction as a detection system. This work demonstrates that the fluorescent assay can be used to quantify the amount of okadaic acid in shellfish samples and also is valid for very dilute samples, such as phytoplankton samples.

Fluorescent Phthalocyanine Assembly Distinguishes Chiral Isomers of Different Types of Amino Acids and Sugars.

PubMed

Jiang, Yuying; Liu, Chenxi; Wang, Xiqian; Wang, Tianyu; Jiang, Jianzhuang

2017-07-25

The functions of some natural supramolecular architectures, such as ribosomes, are dependent on the recognition of different types of chiral biomolecules. However, the recognition of different types of chiral molecules (multiobject chiral recognition), such as amino acids and sugars, by independent and identically artificial supramolecular assembly, was rarely achieved. In this article, simple amphiphilic achiral phthalocyanine was found to form supramolecular chiral assemblies with charged water-soluble polymers upon host-guest interactions at the air/water interface. Among these systems, one identical phthalocyanine/poly(l-lysine) assembly not only can distinguish enantiomers of different amino acids but also can recognize several epimers of monose. The chiral recognitions were achieved by comparing either the steady-state fluorescence intensity or fluorescence quenching rate of phthalocyanine/poly(l-lysine) assemblies, before and after interaction with different small chiral molecules. It was demonstrated that the interactions between poly(l-lysine) and different small chiral molecules could change the aggregation of phthalocyanines. And the sensitivity of fluorescence and the excellent multiobject chiral recognition properties of the phthalocyanine/poly(l-lysine) assembly are dependent on the subtle molecular packing mode and the cooperation of different noncovalent interactions.

Size analysis of polyglutamine protein aggregates using fluorescence detection in an analytical ultracentrifuge.

PubMed

Polling, Saskia; Hatters, Danny M; Mok, Yee-Foong

2013-01-01

Defining the aggregation process of proteins formed by poly-amino acid repeats in cells remains a challenging task due to a lack of robust techniques for their isolation and quantitation. Sedimentation velocity methodology using fluorescence detected analytical ultracentrifugation is one approach that can offer significant insight into aggregation formation and kinetics. While this technique has traditionally been used with purified proteins, it is now possible for substantial information to be collected with studies using cell lysates expressing a GFP-tagged protein of interest. In this chapter, we describe protocols for sample preparation and setting up the fluorescence detection system in an analytical ultracentrifuge to perform sedimentation velocity experiments on cell lysates containing aggregates formed by poly-amino acid repeat proteins.

Real-time assays with molecular beacons and other fluorescent nucleic acid hybridization probes.

PubMed

Marras, Salvatore A E; Tyagi, Sanjay; Kramer, Fred Russell

2006-01-01

A number of formats for nucleic acid hybridization have been developed to identify DNA and RNA sequences that are involved in cellular processes and that aid in the diagnosis of genetic and infectious diseases. The introduction of hybridization probes with interactive fluorophore pairs has enabled the development of homogeneous hybridization assays for the direct identification of nucleic acids. A change in the fluorescence of these probes indicates the presence of a target nucleic acid, and there is no need to separate unbound probes from hybridized probes. The advantages of homogeneous hybridization assays are their speed and simplicity. In addition, homogeneous assays can be combined with nucleic acid amplification, enabling the detection of rare target nucleic acids. These assays can be followed in real time, providing quantitative determination of target nucleic acids over a broad range of concentrations.

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.

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.

Fluorescent nanoaggregates of pentacenequinone derivative for selective sensing of picric acid in aqueous media.

PubMed

Bhalla, Vandana; Gupta, Ankush; Kumar, Manoj

2012-06-15

Novel pentacenequinone derivative 3 has been synthesized using the Suzuki-Miyaura coupling protocol which forms fluorescent nanoaggregates in aqueous media due to its aggregation-induced emission enhancement attributes and selectively senses picric acid with a detection limit of 500 ppb.

Investigation of adsorptive fractionation of humic acid on graphene oxide using fluorescence EEM-PARAFAC.

PubMed

Lee, Bo-Mi; Seo, Young-Soo; Hur, Jin

2015-04-15

In this study, the adsorptive fractionation of a humic acid (HA, Elliott soil humic acid) on graphene oxide (GO) was examined at pH 4 and 6 using absorption spectroscopy and fluorescence excitation-emission matrix (EEM)-parallel factor analysis (PARAFAC). The extent of the adsorption was greater at pH 4.0 than at pH 6.0. Aromatic molecules within the HA were preferentially adsorbed onto the GO surface, and the preferential adsorption was more pronounced at pH 6, which is above the zero point of charge of GO. A relative ratio of two PARAFAC humic-like components (ex/em maxima at 270/510 nm and at (250, 265)/440 nm) presented an increasing trend with larger sizes of ultrafiltered humic acid fractions, suggesting the potential for using fluorescence EEM-PARAFAC for tracking the changes in molecular sizes of aromatic HA molecules. The individual adsorption behaviors of the two humic-like components revealed that larger sized aromatic components within HA had a higher adsorption affinity and more nonlinear isotherms compared to smaller sized fractions. Our results demonstrated that adsorptive fractionation of HA occurred on the GO surface with respect to their aromaticity and the sizes, but the degree was highly dependent on solution pH as well as the amount of adsorbed HS (or available surface sites). The observed adsorption behaviors were reasonably explained by a combination of different mechanisms previously suggested. Copyright © 2015 Elsevier Ltd. All rights reserved.

An ultrasound-guided fluorescence tomography system: design and specification

NASA Astrophysics Data System (ADS)

D'Souza, Alisha V.; Flynn, Brendan P.; Kanick, Stephen C.; Torosean, Sason; Davis, Scott C.; Maytin, Edward V.; Hasan, Tayyaba; Pogue, Brian W.

2013-03-01

An ultrasound-guided fluorescence molecular tomography system is under development for in vivo quantification of Protoporphyrin IX (PpIX) during Aminolevulinic Acid - Photodynamic Therapy (ALA-PDT) of Basal Cell Carcinoma. The system is designed to combine fiber-based spectral sampling of PPIX fluorescence emission with co-registered ultrasound images to quantify local fluorophore concentration. A single white light source is used to provide an estimate of the bulk optical properties of tissue. Optical data is obtained by sequential illumination of a 633nm laser source at 4 linear locations with parallel detection at 5 locations interspersed between the sources. Tissue regions from segmented ultrasound images, optical boundary data, white light-informed optical properties and diffusion theory are used to estimate the fluorophore concentration in these regions. Our system and methods allow interrogation of both superficial and deep tissue locations up to PpIX concentrations of 0.025ug/ml.

Fluorescence Spectroscopy Applied to Monitoring Biodiesel Degradation: Correlation with Acid Value and UV Absorption Analyses.

PubMed

Vasconcelos, Maydla Dos Santos; Passos, Wilson Espíndola; Lescanos, Caroline Honaiser; Pires de Oliveira, Ivan; Trindade, Magno Aparecido Gonçalves; Caires, Anderson Rodrigues Lima; Muzzi, Rozanna Marques

2018-01-01

The techniques used to monitor the quality of the biodiesel are intensely discussed in the literature, partly because of the different oil sources and their intrinsic physicochemical characteristics. This study aimed to monitor the thermal degradation of the fatty acid methyl esters of Sesamum indicum L. and Raphanus sativus L. biodiesels (SILB and RSLB, resp.). The results showed that both biodiesels present a high content of unsaturated fatty acids, ∼84% (SILB) and ∼90% (RSLB). The SILB had a high content of polyunsaturated linoleic fatty acid (18  :  2), about 49%, and the oleic monounsaturated (18  :  1), ∼34%. On the other hand, RSLB presented a considerable content of linolenic fatty acid (18  :  3), ∼11%. The biodiesel samples were thermal degraded at 110°C for 48 hours, and acid value, UV absorption, and fluorescence spectroscopy analysis were carried out. The results revealed that both absorption and fluorescence presented a correlation with acid value as a function of degradation time by monitoring absorptions at 232 and 270 nm as well as the emission at 424 nm. Although the obtained correlation is not completely linear, a direct correlation was observed in both cases, revealing that both properties can be potentially used for monitoring the biodiesel degradation.

Dynamic characterization of hydrophobic and hydrophilic solutes in oleic-acid enhanced transdermal delivery using two-photon fluorescence microscopy

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

Tseng, Te-Yu; Yang, Chiu-Sheng; Chen, Yang-Fang

In this letter, we propose an efficient methodology of investigating dynamic properties of sulforhodamine B and rhodamine B hexyl ester molecules transporting across ex-vivo human stratum corneum with and without oleic acid enhancement. Three-dimensional, time-lapse fluorescence images of the stratum corneum can be obtained using two-photon fluorescence microscopy. Furthermore, temporal quantifications of transport enhancements in diffusion parameters can be achieved with the use of Fick's second law. Dynamic characterization of solutes transporting across the stratum corneum is an effective method for understanding transient phenomena in transdermal delivery of probe molecules, leading to improved delivery strategies of molecular species for therapeuticmore » purposes.« less

Near real time, accurate, and sensitive microbiological safety monitoring using an all-fibre spectroscopic fluorescence system

NASA Astrophysics Data System (ADS)

Vanholsbeeck, F.; Swift, S.; Cheng, M.; Bogomolny, E.

2013-11-01

Enumeration of microorganisms is an essential microbiological task for many industrial sectors and research fields. Various tests for detection and counting of microorganisms are used today. However most of the current methods to enumerate bacteria require either long incubation time for limited accuracy, or use complicated protocols along with bulky equipment. We have developed an accurate, all-fibre spectroscopic system to measure fluorescence signal in-situ. In this paper, we examine the potential of this setup for near real time bacteria enumeration in aquatic environment. The concept is based on a well-known phenomenon that the fluorescence quantum yields of some nucleic acid stains significantly increase upon binding with nucleic acids of microorganisms. In addition we have used GFP labeled organisms. The fluorescence signal increase can be correlated to the amount of nucleic acid present in the sample. In addition we have used GFP labeled organisms. Our results show that we are able to detect a wide range of bacteria concentrations without dilution or filtration (1-108 CFU/ml) using different optical probes we designed. This high sensitivity is due to efficient light delivery with an appropriate collection volume and in situ fluorescence detection as well as the use of a sensitive CCD spectrometer. By monitoring the laser power, we can account for laser fluctuations while measuring the fluorescence signal which improves as well the system accuracy. A synchronized laser shutter allows us to achieve a high SNR with minimal integration time, thereby reducing the photobleaching effect. In summary, we conclude that our optical setup may offer a robust method for near real time bacterial detection in aquatic environment.

4-Pyridoxic Acid in the Spent Dialysate: Contribution to Fluorescence and Optical Monitoring

PubMed Central

Kalle, Sigrid; Tanner, Risto; Arund, Jürgen; Tomson, Ruth; Luman, Merike; Fridolin, Ivo

2016-01-01

Aim In this work we estimated the contribution of the fluorescence of 4-pyridoxic acid (4-PA) to the total fluorescence of spent dialysate with the aim of evaluating the on-line monitoring of removal of this vitamin B-6 metabolite from the blood of patients with end-stage renal disease (ESRD). Methods Spectrofluorometric analysis of spent dialysate, collected from hemodialysis and hemodiafiltration sessions of 10 patients receiving regularly pyridoxine injections after dialysis treatment, was performed in the range of Ex/Em 220–500 nm. 4-PA in dialysate samples was identified and quantified using HPLC with fluorescent and MS/MS detection. Results Averaged HPLC chromatogram of spent dialysate had many peaks in the wavelength region of Ex320/Em430 nm where 4-PA was the highest peak with contribution of 42.2±17.0% at the beginning and 47.7±18.0% in the end of the dialysis. High correlation (R = 0.88–0.95) between 4-PA concentration and fluorescence intensity of spent dialysate was found in the region of Ex310-330/Em415-500 nm, respectively. Conclusion 4-PA elimination from the blood of ESRD patients can be potentially followed using monitoring of the fluorescence of the spent dialysate during dialysis treatments. PMID:27598005

4-Pyridoxic Acid in the Spent Dialysate: Contribution to Fluorescence and Optical Monitoring.

PubMed

Kalle, Sigrid; Tanner, Risto; Arund, Jürgen; Tomson, Ruth; Luman, Merike; Fridolin, Ivo

2016-01-01

In this work we estimated the contribution of the fluorescence of 4-pyridoxic acid (4-PA) to the total fluorescence of spent dialysate with the aim of evaluating the on-line monitoring of removal of this vitamin B-6 metabolite from the blood of patients with end-stage renal disease (ESRD). Spectrofluorometric analysis of spent dialysate, collected from hemodialysis and hemodiafiltration sessions of 10 patients receiving regularly pyridoxine injections after dialysis treatment, was performed in the range of Ex/Em 220-500 nm. 4-PA in dialysate samples was identified and quantified using HPLC with fluorescent and MS/MS detection. Averaged HPLC chromatogram of spent dialysate had many peaks in the wavelength region of Ex320/Em430 nm where 4-PA was the highest peak with contribution of 42.2±17.0% at the beginning and 47.7±18.0% in the end of the dialysis. High correlation (R = 0.88-0.95) between 4-PA concentration and fluorescence intensity of spent dialysate was found in the region of Ex310-330/Em415-500 nm, respectively. 4-PA elimination from the blood of ESRD patients can be potentially followed using monitoring of the fluorescence of the spent dialysate during dialysis treatments.

A fluorescent sensor based on thioglycolic acid capped cadmium sulfide quantum dots for the determination of dopamine

NASA Astrophysics Data System (ADS)

Kulchat, Sirinan; Boonta, Wissuta; Todee, Apinya; Sianglam, Pradthana; Ngeontae, Wittaya

2018-05-01

A fluorescent sensor based on thioglycolic acid-capped cadmium sulfide quantum dots (TGA-CdS QDs) has been designed for the sensitive and selective detection of dopamine (DA). In the presence of dopamine (DA), the addition of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) activates the reaction between the carboxylic group of the TGA and the amino group of dopamine to form an amide bond, quenching the fluorescence of the QDs. The fluorescence intensity of TGA-CdS QDs can be used to sense the presence of dopamine with a limit of detection of 0.68 μM and a working linear range of 1.0-17.5 μM. This sensor system shows great potential application for dopamine detection in dopamine drug samples and for future easy-to-make analytical devices.

Transport characteristics of three fluorescent conjugated bile acid analogs in isolated rat hepatocytes and couplets.

PubMed

Maglova, L M; Jackson, A M; Meng, X J; Carruth, M W; Schteingart, C D; Ton-Nu, H T; Hofmann, A F; Weinman, S A

1995-08-01

The transport properties of three different synthetically prepared fluorescent conjugated bile acid analogs (FBA), all with the fluorophore on the side chain, were determined using isolated rat hepatocytes and hepatocyte couplets. The compounds studied were cholylglycylamidofluorescein (CGamF), cholyl(N epsilon-nitrobenzoxadiazolyl [NBD])-lysine (C-NBD-L), and chenodeoxycholyl-(N epsilon-NBD)-lysine (CDC-NBD-L). When hepatocytes were incubated at 37 degrees C with 0.3 mumol/L of FBA and 0.15 mol/L of Na+, cell fluorescence increased linearly with time at a rate (U/min) of 7.8 +/- 0.5 for CGamF, 7.2 +/- 0.3 for C-NBD-L, and 13.7 +/- 1.0 for CDC-NBD-L (mean, +/- SE; n = 40 to 90). Uptake was concentration dependent for concentrations less than 20 mumol/L and was saturable. The Michaelis constant (Km) value (mumol/L) for CGamF was 10.8, for C-NBD-L was 3.8, and for CDC-NBD-L was 3.0. In the absence of Na+, the uptake rate was decreased by 50% for CGamF and by 38% for C-NBD-L; but uptake of CDC-NBD-L was unchanged and thus Na+ independent. Cellular uptake of all three derivatives was specific to hepatocytes and was absent in several nonhepatocyte cell lines. For CGamF and C-NBD-L, both Na(+)-dependent and Na(+)-independent uptake was inhibited by 200-fold excess concentrations of cholyltaurine, dehydrocholyltaurine, and cholate, but for CDC-NBD-L, these nonfluorescent bile acids did not inhibit initial uptake. The intracellular fluorescence of CGamF was strongly pH dependent at an excitation wavelength of 495 nm, but pH independent at 440 nm excitation. In contrast, intracellular fluorescence of C-NBD-L and CDC-NBD-L was pH independent. All three FBA were secreted into the canalicular space of approximately 50% to 60% of couplets. Cellular adenosine triphosphate (ATP) depletion with either CN- or atractyloside inhibited secretion of all three FBA. The multispecific organic anion transporter (MOAT) inhibitor, chlorodinitrobenzene, blocked secretion of fluorescent MOAT

A single pH fluorescent probe for biosensing and imaging of extreme acidity and extreme alkalinity.

PubMed

Chao, Jian-Bin; Wang, Hui-Juan; Zhang, Yong-Bin; Li, Zhi-Qing; Liu, Yu-Hong; Huo, Fang-Jun; Yin, Cai-Xia; Shi, Ya-Wei; Wang, Juan-Juan

2017-07-04

A simple tailor-made pH fluorescent probe 2-benzothiazole (N-ethylcarbazole-3-yl) hydrazone (Probe) is facilely synthesized by the condensation reaction of 2-hydrazinobenzothiazole with N-ethylcarbazole-3-formaldehyde, which is a useful fluorescent probe for monitoring extremely acidic and alkaline pH, quantitatively. The pH titrations indicate that Probe displays a remarkable emission enhancement with a pK a of 2.73 and responds linearly to minor pH fluctuations within the extremely acidic range of 2.21-3.30. Interestingly, Probe also exhibits strong pH-dependent characteristics with pK a 11.28 and linear response to extreme-alkalinity range of 10.41-12.43. In addition, Probe shows a large Stokes shift of 84 nm under extremely acidic and alkaline conditions, high selectivity, excellent sensitivity, good water-solubility and fine stability, all of which are favorable for intracellular pH imaging. The probe is further successfully applied to image extremely acidic and alkaline pH values fluctuations in E. coli cells. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Blood interference in fiber-optical based fluorescence guided resection of glioma using 5-aminolevulinic acid

NASA Astrophysics Data System (ADS)

Haj-Hosseini, Neda; Lowndes, Shannely; Salerud, Göran; Wårdell, Karin

2011-03-01

Fluorescence guidance in brain tumor resection is performed intra-operatively where bleeding is included. When using fiber-optical probes, the transmission of light to and from the tissue is totally or partially blocked if a small amount of blood appears in front of the probe. Sometimes even after rinsing with saline, the remnant blood cells on the optical probe head, disturb the measurements. In such a case, the corresponding spectrum cannot be reliably quantified and is therefore discarded. The optimal case would be to calculate and take out the blood effect systematically from the collected signals. However, the first step is to study the pattern of blood interference in the fluorescence spectrum. In this study, a fiber-optical based fluorescence spectroscopy system with a laser excitation light of 405 nm (1.4 J/cm2) was used during fluorescence guided brain tumor resection using 5-aminolevulinic acid (5-ALA). The blood interference pattern in the fluorescence spectrum collected from the brain was studied in two patients. The operation situation was modeled in the laboratory by placing blood drops from the finger tip on the skin of forearm and the data was compared to the brain in vivo measurements. Additionally, a theoretical model was developed to simulate the blood interference pattern on the skin autofluorescence. The blood affects the collected fluorescence intensity and leaves traces of oxy and deoxy-hemoglobin absorption peaks. According to the developed theoretical model, the autofluorescence signal is considered to be totally blocked by an approximately 500 μm thick blood layer.

Photolysis of Indole-Containing Mycotoxins to Fluorescent Products

USDA-ARS?s Scientific Manuscript database

Photochemical reaction of the non-fluorescent mycotoxin cyclopiazonic acid (CPA) to fluorescent products was recently reported. Because CPA contains an indole moiety, believed to contribute to the fluorescence, it was of interest to determine whether the effect might be more generally applicable to ...

Combining 5-Aminolevulinic Acid Fluorescence and Intraoperative Magnetic Resonance Imaging in Glioblastoma Surgery: A Histology-Based Evaluation.

PubMed

Hauser, Sonja B; Kockro, Ralf A; Actor, Bertrand; Sarnthein, Johannes; Bernays, René-Ludwig

2016-04-01

Glioblastoma resection guided by 5-aminolevulinic acid (5-ALA) fluorescence and intraoperative magnetic resonance imaging (iMRI) may improve surgical results and prolong survival. To evaluate 5-ALA fluorescence combined with subsequent low-field iMRI for resection control in glioblastoma surgery. Fourteen patients with suspected glioblastoma suitable for complete resection of contrast-enhancing portions were enrolled. The surgery was carried out using 5-ALA-induced fluorescence and frameless navigation. Areas suspicious for tumor underwent biopsy. After complete resection of fluorescent tissue, low-field iMRI was performed. Areas suspicious for tumor remnant underwent biopsy under navigation guidance and were resected. The histological analysis was blinded. In 13 of 14 cases, the diagnosis was glioblastoma multiforme. One lymphoma and 1 case without fluorescence were excluded. In 11 of 12 operations, residual contrast enhancement on iMRI was found after complete resection of 5-ALA fluorescent tissue. In 1 case, the iMRI enhancement was in an eloquent area and did not undergo a biopsy. The 28 biopsies of areas suspicious for tumor on iMRI in the remaining 10 cases showed tumor in 39.3%, infiltration zone in 25%, reactive central nervous system tissue in 32.1%, and normal brain in 3.6%. Ninety-three fluorescent and 24 non-fluorescent tissue samples collected before iMRI contained tumor in 95.7% and 87.5%, respectively. 5-ALA fluorescence-guided resection may leave some glioblastoma tissue undetected. MRI might detect areas suspicious for tumor even after complete resection of all fluorescent tissue; however, due to the limited accuracy of iMRI in predicting tumor remnant (64.3%), resection of this tissue has to be considered with caution in eloquent regions.

A simple and sensitive fluorescence based biosensor for the determination of uric acid using H2O2-sensitive quantum dots/dual enzymes.

PubMed

Azmi, Nur Ellina; Ramli, Noor Izaanin; Abdullah, Jaafar; Abdul Hamid, Mohammad Azmi; Sidek, Hamidah; Abd Rahman, Samsulida; Ariffin, Nurhayati; Yusof, Nor Azah

2015-05-15

A novel optical detection system consisting of combination of uricase/HRP-CdS quantum dots (QDs) for the determination of uric acid in urine sample is described. The QDs was used as an indicator to reveal fluorescence property of the system resulting from enzymatic reaction of uricase and HRP (horseradish peroxidase), which is involved in oxidizing uric acid to allaintoin and hydrogen peroxide. The hydrogen peroxide produced was able to quench the QDs fluorescence, which was proportional to uric acid concentration. The system demonstrated sufficient activity of uricase and HRP at a ratio of 5U:5U and pH 7.0. The linearity of the system toward uric acid was in the concentration range of 125-1000 µM with detection limit of 125 µM. Copyright © 2014 Elsevier B.V. All rights reserved.

Analysis of fluorescently labeled glycosphingolipid-derived oligosaccharides following ceramide glycanase digestion and anthranilic acid labeling.

PubMed

Neville, David C A; Coquard, Virginie; Priestman, David A; te Vruchte, Danielle J M; Sillence, Daniel J; Dwek, Raymond A; Platt, Frances M; Butters, Terry D

2004-08-15

Interest in cellular glycosphingolipid (GSL) function has necessitated the development of a rapid and sensitive method to both analyze and characterize the full complement of structures present in various cells and tissues. An optimized method to characterize oligosaccharides released from glycosphingolipids following ceramide glycanase digestion has been developed. The procedure uses the fluorescent compound anthranilic acid (2-aminobenzoic acid; 2-AA) to label oligosaccharides prior to analysis using normal-phase high-performance liquid chromatography. The labeling procedure is rapid, selective, and easy to perform and is based on the published method of Anumula and Dhume [Glycobiology 8 (1998) 685], originally used to analyze N-linked oligosaccharides. It is less time consuming than a previously published 2-aminobenzamide labeling method [Anal. Biochem. 298 (2001) 207] for analyzing GSL-derived oligosaccharides, as the fluorescent labeling is performed on the enzyme reaction mixture. The purification of 2-AA-labeled products has been improved to ensure recovery of oligosaccharides containing one to four monosaccharide units, which was not previously possible using the Anumula and Dhume post-derivatization purification procedure. This new approach may also be used to analyze both N- and O-linked oligosaccharides.

An efficient core-shell fluorescent silica nanoprobe for ratiometric fluorescence detection of pH in living cells.

PubMed

Fu, Jingni; Ding, Changqin; Zhu, Anwei; Tian, Yang

2016-08-07

Intracellular pH plays a vital role in cell biology, including signal transduction, ion transport and homeostasis. Herein, a ratiometric fluorescent silica probe was developed to detect intracellular pH values. The pH sensitive dye fluorescein isothiocyanate isomer I (FITC), emitting green fluorescence, was hybridized with reference dye rhodamine B (RB), emitting red fluorescence, as a dual-emission fluorophore, in which RB was embedded in a silica core of ∼40 nm diameter. Moreover, to prevent fluorescence resonance energy transfer between FITC and RB, FITC was grafted onto the surface of core-shell silica colloidal particles with a shell thickness of 10-12 nm. The nanoprobe exhibited dual emission bands centered at 517 and 570 nm, under single wavelength excitation of 488 nm. RB encapsulated in silica was inert to pH change and only served as reference signals for providing built-in correction to avoid environmental effects. Moreover, FITC (λem = 517 nm) showed high selectivity toward H(+) against metal ions and amino acids, leading to fluorescence variation upon pH change. Consequently, variations of the two fluorescence intensities (Fgreen/Fred) resulted in a ratiometric pH fluorescent sensor. The specific nanoprobe showed good linearity with pH variation in the range of 6.0-7.8. It can be noted that the fluorescent silica probe demonstrated good water dispersibility, high stability and low cytotoxicity. Accordingly, imaging and biosensing of pH variation was successfully achieved in HeLa cells.

Quenching of fluorescence of phenolic compounds and modified humic acids by cadmium ions.

PubMed

Tchaikovskaya, O N; Nechaev, L V; Yudina, N V; Mal'tseva, E V

2016-08-01

The interaction of a number of phenolic compounds, being 'model fragments' of humic acids, with cadmium ions was investigated. The fluorescence quenching method was used to determine the complexation constants of these compounds with cadmium ions. It was established that bonding of phenolic compounds by cadmium ions at рН 7 is weak and reaches a maximum value of 15% for interaction with resorcinol. It was demonstrated that modification of humic acids by the mechanoactivation method increases by three times bonding of cadmium ions, which is caused by strengthening the acid properties of carboxyl and hydroxyl groups at the aromatic ring. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

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

NASA Astrophysics Data System (ADS)

Nguyen, Khac Hong; Hao, Yuanqiang; Zeng, Ke; Fan, Shengnan; Li, Fen; Yuan, Suke; Ding, Xuejing; Xu, Maotian; Liu, You-Nian

2018-06-01

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

Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid

PubMed Central

Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

2016-01-01

The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane. PMID:27330112

Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid.

PubMed

Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

2016-07-05

The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane.

Intra-operative visualization of brain tumors with 5-aminolevulinic acid-induced fluorescence.

PubMed

Widhalm, Georg

2014-01-01

Precise histopathological diagnosis of brain tumors is essential for the correct patient management. Furthermore, complete resection of brain tumors is associated with an improved patient prognosis. However, histopathological undergrading and incomplete tumor removal are not uncommon, especially due to insufficient intra-operative visualization of brain tumor tissue. The fluorescent dye 5-aminolevulinic acid (5-ALA) is currently applied for fluorescence-guided resections of high-grade gliomas. The value of 5-ALA-induced protoporphyrin (PpIX) fluorescence for intra-operative visualization of other tumors than high-grade gliomas remains unclear. Within the frame of this thesis, we found a significantly higher rate of complete resections of our high-grade gliomas as compared to control cases by using the newly established 5-ALA fluorescence technology at our department. Additionally, we showed that MRI spectroscopy-based chemical shift imaging (CSI) is capable to identify intratumoral high-grade glioma areas (= anaplastic foci) during navigation guided resections to avoid histopathological undergrading. However, the accuracy of navigation systems with integrated pre-operative imaging data such as CSI declines during resections due to intra-operative brainshift. In two further studies, we found that 5-ALA induced PpIX fluorescence is capable as a novel intra-operative marker to detect anaplastic foci within initially suspected low-grade gliomas independent of brainshift. Finally, we showed that the application of 5-ALA is also of relevance in needle biopsies for intra-operative identification of representative brain tumor tissue. These data indicate that 5-ALA is not only of major importance for resection of high-grade gliomas, but also for intra-operative visualization of anaplastic foci as well as representative brain tumor tissue in needle biopsies unaffected by brainshift. Consequently, this new technique might become a novel standard in brain tumor surgery that

Structural and dynamic changes associated with beneficial engineered single-amino-acid deletion mutations in enhanced green fluorescent protein

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

Arpino, James A. J.; Rizkallah, Pierre J., E-mail: rizkallahp@cardiff.ac.uk; Jones, D. Dafydd, E-mail: rizkallahp@cardiff.ac.uk

2014-08-01

The beneficial engineered single-amino-acid deletion variants EGFP{sup D190Δ} and EGFP{sup A227Δ} have been studied. Single-amino-acid deletions are a common part of the natural evolutionary landscape but are rarely sampled during protein engineering owing to limited and prejudiced molecular understanding of mutations that shorten the protein backbone. Single-amino-acid deletion variants of enhanced green fluorescent protein (EGFP) have been identified by directed evolution with the beneficial effect of imparting increased cellular fluorescence. Biophysical characterization revealed that increased functional protein production and not changes to the fluorescence parameters was the mechanism that was likely to be responsible. The structure EGFP{sup D190Δ} containing amore » deletion within a loop revealed propagated changes only after the deleted residue. The structure of EGFP{sup A227Δ} revealed that a ‘flipping’ mechanism was used to adjust for residue deletion at the end of a β-strand, with amino acids C-terminal to the deletion site repositioning to take the place of the deleted amino acid. In both variants new networks of short-range and long-range interactions are generated while maintaining the integrity of the hydrophobic core. Both deletion variants also displayed significant local and long-range changes in dynamics, as evident by changes in B factors compared with EGFP. Rather than being detrimental, deletion mutations can introduce beneficial structural effects through altering core protein properties, folding and dynamics, as well as function.« less

Fluorescence of bioaerosols: mathematical model including primary fluorescing and absorbing molecules in bacteria.

PubMed

Hill, Steven C; Pan, Yong-Le; Williamson, Chatt; Santarpia, Joshua L; Hill, Hanna H

2013-09-23

This paper describes a mathematical model of fluorescent biological particles composed of bacteria, viruses, or proteins. The fluorescent and/or light absorbing molecules included in the model are amino acids (tryptophan, etc.); nucleic acids (DNA, RNA, etc.); coenzymes (nicotinamide adenine dinucleotides, flavins, and vitamins B₆ and K and variants of these); and dipicolinates. The concentrations, absorptivities, and fluorescence quantum yields are estimated from the literature, often with large uncertainties. The bioparticles in the model are spherical and homogeneous. Calculated fluorescence cross sections for particles excited at 266, 280, and 355 nm are compared with measured values from the literature for several bacteria, bacterial spores and albumins. The calculated 266- and 280-nm excited fluorescence is within a factor of 3.2 of the measurements for the vegetative cells and proteins, but overestimates the fluorescence of spores by a factor of 10 or more. This is the first reported modeling of the fluorescence of bioaerosols in which the primary fluorophores and absorbing molecules are included.

Enantioselective micellar electrokinetic chromatography of dl-amino acids using (+)-1-(9-fluorenyl)-ethyl chloroformate derivatization and UV-induced fluorescence detection.

PubMed

Prior, Amir; van de Nieuwenhuijzen, Erik; de Jong, Gerhardus J; Somsen, Govert W

2018-05-22

Chiral analysis of dl-amino acids was achieved by micellar electrokinetic chromatography coupled with UV-excited fluorescence detection. The fluorescent reagent (+)-1-(9-fluorenyl)ethyl chloroformate was employed as chiral amino acid derivatizing agent and sodium dodecyl sulfate served as pseudo-stationary phase for separating the formed amino acid diastereomers. Sensitive analysis of (+)-1-(9-fluorenyl)ethyl chloroformate-amino acids was achieved applying a xenon-mercury lamp for ultraviolet excitation, and a spectrograph and charge-coupled device for wavelength-resolved emission detection. Applying signal integration over a 30-nm emission wavelength interval, signal-to-noise ratios for derivatized amino acids were up to 23 times higher as obtained using a standard photomultiplier for detection. The background electrolyte composition (electrolyte, pH, sodium dodecyl sulfate concentration, and organic solvent) was studied in order to attain optimal chemo- and enantioseparation. Enantioseparation of twelve proteinogenic dl-amino acids was achieved with chiral resolutions between 1.2 and 7.9, and detection limits for most derivatized amino acids in the 13-60 nM range (injected concentration). Linearity (coefficients of determination > 0.985) and peak-area and migration-time repeatabilities (relative standard deviations lower than 2.6 and 1.9%, respectively) were satisfactory. The employed fluorescence detection system provided up to 100-times better signal-to-noise ratios for (+)-1-(9-fluorenyl)ethyl chloroformate-amino acids than ultraviolet absorbance detection, showing good potential for d-amino acid analysis. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Use of 5-aminolevulinic acid in fluorescence-guided resection of meningioma with high risk of recurrence. Case report.

PubMed

Kajimoto, Yoshinaga; Kuroiwa, Toshihiko; Miyatake, Shin-Ichi; Ichioka, Tsugumichi; Miyashita, Minoru; Tanaka, Hidekazu; Tsuji, Motomu

2007-06-01

It has been established that fluorescence-guided resection using 5-aminolevulinic acid (5-ALA) is useful in glioma surgery. The authors report on a 65-year-old woman who had a huge atypical left-hemisphere meningioma, which extended into the skull and to the superior sagittal sinus and demonstrated fluorescence in response to administration of 5-ALA. After the tumor was removed, the operative field was observed under the fluorescent mode of a fluorescence surgical microscopy system. Several minute areas of residual tumor tissue were visualized as strong fluorescence behind the vein and sinus, in a part of the hypertrophic dura, and along the edge of the skull. These remnants were completely removed. The authors concluded that fluorescence-guided resection using 5-ALA is useful in cases of atypical meningiomas with a high risk of recurrence.

The fluorescent property of 3-[(2-hydroxy-1-naphthyl) methylideneamino]benzoic acid and its application as fluorescent chemosensor for Hg2 + and Al3 + ions

NASA Astrophysics Data System (ADS)

Sun, Changyan; Sun, Jiayi; Qiu, Fazheng; Li, Wenjun; Chang, Zhidong; Zhang, Lijun

2018-01-01

This manuscript studies the fluorescent property of 3-[(2-hydroxy-1-naphthyl)methylideneamino]benzoic acid (H2L). Fluorescent spectra show that in different solvents, H2L displays different fluorescent properties, which can be attributed to the interaction between the solvents and H2L. Further study indicates that H2L exhibits a highly selective and sensitive recognition for Hg2 + ions in dimethylsulfoxide (DMSO), Al3 + ions in methanol and N,N‧-dimethylformamide/water (DMF/H2O, 1/1, v/v). The bonding modes and bonding ratio of H2L and metal ions in different solvents are explored by Job's plot, 1H NMR titration, and electrospray ionization mass spectrometry (ESI-MS). The probable mechanisms were discussed.

Determination of arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid in cereals by hydride generation atomic fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Matos Reyes, M. N.; Cervera, M. L.; Campos, R. C.; de la Guardia, M.

2007-09-01

A fast, sensitive and simple non-chromatographic analytical method was developed for the speciation analysis of toxic arsenic species in cereal samples, namely rice and wheat semolina. An ultrasound-assisted extraction of the toxic arsenic species was performed with 1 mol L - 1 H 3PO 4 and 0.1% (m/v) Triton XT-114. After extraction, As(III), As(V), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) concentrations were determined by hydride generation atomic fluorescence spectrometry using a series of proportional equations corresponding to four different experimental reduction conditions. The detection limits of the method were 1.3, 0.9, 1.5 and 0.6 ng g - 1 for As(III), As(V), DMA and MMA, respectively, expressed in terms of sample dry weight. Recoveries were always greater than 90%, and no species interconversion occurred. The speciation analysis of a rice flour reference material certified for total arsenic led to coherent results, which were also in agreement with other speciation studies made on the same certified reference material.

Dual color fluorescence quantitative detection of specific single-stranded DNA with molecular beacons and nucleic acid dye SYBR Green I.

PubMed

Xiang, Dong-Shan; Zhou, Guo-Hua; Luo, Ming; Ji, Xing-Hu; He, Zhi-Ke

2012-08-21

We have developed a dual color fluorescence quantitative detection method for specific single-stranded DNA with molecular beacons (MBs) and nucleic acid dye SYBR Green I by synchronous scanning fluorescence spectrometry. It is demonstrated by a reverse-transcription oligonucleotide sequence (target DNA, 33 bases) of RNA fragment of human immunodeficiency virus (HIV) as a model system. In the absence of target DNA, the MBs are in the stem-closed state, the fluorescence of 5-carboxy-X-rhodamine (ROX) is quenched by black hole quencher-2 (BHQ-2), and the interaction between SYBR Green I and the MBs is very weak. At this time the fluorescence signals of ROX and SYBR Green I are all very weak. In the presence of target DNA, MBs hybridize with target DNA and form a double-strand structure, the fluorophore ROX is separated from the quencher BHQ-2, and the fluorescence of ROX recovers. At the same time, SYBR Green I binds to hybridized dsDNA, whose fluorescence intensity is significantly enhanced. Thus, dual color fluorescence quantitative detection for the target DNA can be realized by synchronous scanning fluorescence spectrometry. In this strategy, the fluorescence signal of SYBR Green I is far larger than that of ROX, so the quantitative analysis of target DNA with the fluorescence intensity of SYBR Green I can significantly improve the detection sensitivity. In addition, the false-positive signals of MBs do not affect the fluorescence signals of nucleic acid dye SYBR Green I. Thereby, in the analysis of complex samples, quantitative analysis of target DNA with SYBR Green I can avoid the false-positive signals of MBs and improve the detection accuracy.

Detection of nitrite based on fluorescent carbon dots by the hydrothermal method with folic acid

NASA Astrophysics Data System (ADS)

Lin, Haitao; Ding, Liyun; Zhang, Bingyu; Huang, Jun

2018-05-01

A fluorescent carbon dots probe for the detection of aqueous nitrite was fabricated by a one-pot hydrothermal method, and the transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer were used to study the property of carbon dots. The fluorescent property of carbon dots influenced by the concentration of aqueous nitrite was studied. The interaction between the electron-donating functional groups and the electron-accepting nitrous acid could account for the quenching effect on carbon dots by adding aqueous nitrite. The products of the hydrolysis of aqueous nitrite performed a stronger quenching effect at lower pH. The relationship between the relative fluorescence intensity of carbon dots and the concentration of nitrite was described by the Stern-Volmer equation (I0/I - 1 = 0.046[Q]) with a fine linearity (R2 = 0.99). The carbon dots-based probe provides a convenient method for the detection of nitrite concentration.

[Effects of soil acidity on Pinus resinosa seedlings photosynthesis and chlorophyll fluorescence].

PubMed

Liu, Shuang; Wang, Qing-cheng; Liu, Ya-li; Tian, Yu-ming; Sun, Jing; Xu, Jing

2009-12-01

Red pine (Pinus resinosa) is one of the most important tree species for timber plantation in North America, and preliminary success has been achieved in its introduction to the mountainous area of Northeast China since 2004. In order to expand its growth area in other parts of Northeast China, a pot experiment was conducted to study the adaptability of this tree species to varying soil acidity. P. resinosa seedlings were grown in soils with different acidity (pH = 4.5, 5.5, 6.5, 7.5, and 8.0) to test the responses of their photosynthesis and chlorophyll fluorescence parameters to soil pH levels, and the appropriate soil acidity was evaluated. Dramatic responses in chlorophyll a and b contents, Pn and chlorophyll fluorescence parameters (Fo, Fm, Fv, Fv/Fm, and phi(PS II)) were detected under different soil acidity (P < 0.05), with the highest chlorophyll content and Pn under soil pH 5.5, and significantly lower chlorophyll content and Pn under soil pH 7.5 and 8.0. The chlorophyll content and Pn were 41% and 50%, and 61% and 88% higher under soil pH 5.5 than under soil pH 7.5 and 8.0. The seedlings had a significant photosynthetic inhibition under soil pH 7.5 and 8.0, but the highest Fv/Fm and phi (PS II) under soil pH 5.5. Comparing with those under soil pH 7.5 and 8.0, the Fv/Fm and phi (PS II) under soil pH 5.5 were 8% and 12%, and 22% and 35% higher, respectively. It was suggested that soil pH 5.5 was most appropriate for P. resinosa growth.

Determination of aristolochic acids by high-performance liquid chromatography with fluorescence detection.

PubMed

Wang, Yinan; Chan, Wan

2014-06-25

Nephrotoxic and carcinogenic aristolochic acids (AAs) are naturally occurring nitrophenanthrene carboxylic acids in the herbal genus Aristolochia. The misuse of AA-containing herbs in preparing slimming drugs has caused hundred of cases of kidney disease in Belgium women in a slimming regime in the early 1990s. Accumulating evidence also suggested that prolong dietary intake of AA-contaminated food is one of the major causes to the Balkan endemic nephropathy that was first observed in the late 1950s. Therefore, analytical methods of high sensitivity are extremely important for safeguarding human exposure to AA-containing herbal medicines, herbal remedies, and food composites. In this paper, we describe the development of a new high-performance liquid chromatography coupled fluorescence detector (HPLC-FLD) method for the sensitive determination of AAs. The method makes use of a novel cysteine-induced denitration reaction that "turns on" the fluorescence of AAs for fluorometric detections. Our results showed that the combination of cysteine-induced denitration and HPLC-FLD analysis allows for sensitive quantification of AA-I and AA-II at detection limits of 27.1 and 25.4 ng/g, respectively. The method was validated and has been successfully applied in quantifying AAs in Chinese herbal medicines.

Chromophore Structure of Photochromic Fluorescent Protein Dronpa: Acid-Base Equilibrium of Two Cis Configurations.

PubMed

Higashino, Asuka; Mizuno, Misao; Mizutani, Yasuhisa

2016-04-07

Dronpa is a novel photochromic fluorescent protein that exhibits fast response to light. The present article is the first report of the resonance and preresonance Raman spectra of Dronpa. We used the intensity and frequency of Raman bands to determine the structure of the Dronpa chromophore in two thermally stable photochromic states. The acid-base equilibrium in one photochromic state was observed by spectroscopic pH titration. The Raman spectra revealed that the chromophore in this state shows a protonation/deprotonation transition with a pKa of 5.2 ± 0.3 and maintains the cis configuration. The observed resonance Raman bands showed that the other photochromic state of the chromophore is in a trans configuration. The results demonstrate that Raman bands selectively enhanced for the chromophore yield valuable information on the molecular structure of the chromophore in photochromic fluorescent proteins after careful elimination of the fluorescence background.

5-Aminolevulinic Acid-Induced Fluorescence in Cerebellar Primary Central Nervous System Lymphoma: A Case Report and Literature Review.

PubMed

Yamamoto, Junkoh; Kitagawa, Takehiro; Akiba, Daisuke; Nishizawa, Shigeru

2015-01-01

5-Aminolevulinic acid (5-ALA)-induced fluorescence-guided resection is a widely used procedure for patients with malignant gliomas. However, the clinical application of 5-ALA for surgery in primary central nervous system lymphoma (PCNSL) is uncommon. Here, we present a case of PCNSL treated using 5-ALA-induced fluorescence-guided resective surgery. A 70-year-old woman presented with cerebellar ataxia, and magnetic resonance imaging revealed an irregularly shaped and homogenously enhanced mass with surrounding brain edema in the vermis that extended to the right hemisphere of the cerebellum. Under the preoperative diagnosis of a malignant glioma in the cerebellum, the patient underwent 5-ALA-induced fluorescence-guided surgery. Under blue light illumination, the tumor revealed strong 5-ALA-induced fluorescence. The tumor was identified as a diffuse large B-cell lymphoma. After partial resection, the patient received adjuvant chemotherapy and radiotherapy. Importantly, the neurological deficit of the patient improved, and recurrence of the tumor was not observed 21 months post-surgery. Together with previous reports, this case study emphasizes the efficacy of the surgical application of 5-ALA for PCNSL.

A novel cyanide-selective colorimetric and fluorescent chemosensor: first molecular security keypad lock based on phosphotungstic acid and CN- inputs.

PubMed

Tavallali, Hossein; Deilamy-Rad, Gohar; Parhami, Abolfath; Hasanli, Nahid

2014-02-15

Rhodamine B (RhB) an available dye has been developed as novel and efficient colorimetric and fluorometric chemosensor for cyanide ions in an absolutely aqueous media. The UV-vis absorption and fluorescent emission titrations experiments have been employed to study the sensing process. RhB could act as an efficient "ON-OFF" fluorescent response for phosphotungstic acid (H3PW12O40 or PTA) based on an ion associate process. Also (RhB(+))3 · PTA(3-) could operate as an "OFF-ON" fluorescent sensor for cyanide anions based on a ligand substitution process. It has been identified as highly sensitive probe for CN(-) which responds at 0.3 and 0.04 μmol L(-1) concentration levels by absorption and fluorescent method respectively. Depending upon the sequence of addition of PTA and CN(-) ions into the solution, RhB could be as a molecular security keypad lock with PTA and CN(-) inputs. The ionic inputs to new fluorophore have been mimicked as a superimposed electronic molecular keypad lock. The results were compared successfully (>96%) with the data of a spectrophotometry approved method (EPA 9014-1) for cyanide ions. Copyright © 2013 Elsevier B.V. All rights reserved.

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

Boric-Acid-Functional Lanthanide Metal-Organic Frameworks for Selective Ratiometric Fluorescence Detection of Fluoride Ions.

PubMed

Yang, Zhong-Rui; Wang, Man-Man; Wang, Xue-Sheng; Yin, Xue-Bo

2017-02-07

Here, we report that boric acid is used to tune the optical properties of lanthanide metal-organic frameworks (LMOFs) for dual-fluorescence emission and improves the selectivity of LMOFs for the determination of F - ions. The LMOFs are prepared with 5-boronoisophthalic acid (5-bop) and Eu 3+ ions as the precursors. Emission mechanism study indicates that 5-bop is excited with UV photons to produce its triplet state, which then excites Eu 3+ ions for their red emission. This is the general story of the antenna effect, but electron-deficient boric acid decreases the energy transfer efficiency from the triplet state of 5-bop to Eu 3+ ions, so dual emission from both 5-bop and Eu 3+ ions is efficiently excited at the single excitation of 275 nm. Moreover, boric acid is used to identify fluoride specifically as a free accessible site. The ratiometric fluorescent detection of F - ions is validated with the dual emission at single excitation. The LMOFs are very monodisperse, so the determination of aqueous F - ions is easily achieved with high selectivity and a low detection limit (2 μM). For the first time, we reveal that rational selection of functional ligands can improve the sensing efficiency of LMOFs through tuning their optical property and enhancing the selectivity toward targets.

Detection of nucleic acid-protein interactions in plant leaves using fluorescence lifetime imaging microscopy.

PubMed

Camborde, Laurent; Jauneau, Alain; Brière, Christian; Deslandes, Laurent; Dumas, Bernard; Gaulin, Elodie

2017-09-01

DNA-binding proteins (DNA-BPs) and RNA-binding proteins (RNA-BPs) have critical roles in living cells in all kingdoms of life. Various experimental approaches exist for the study of nucleic acid-protein interactions in vitro and in vivo, but the detection of such interactions at the subcellular level remains challenging. Here we describe how to detect nucleic acid-protein interactions in plant leaves by using a fluorescence resonance energy transfer (FRET) approach coupled to fluorescence lifetime imaging microscopy (FLIM). Proteins of interest (POI) are tagged with a GFP and transiently expressed in plant cells to serve as donor fluorophore. After sample fixation and cell wall permeabilization, leaves are treated with Sytox Orange, a nucleic acid dye that can function as a FRET acceptor. Upon close association of the GFP-tagged POI with Sytox-Orange-stained nucleic acids, a substantial decrease of the GFP lifetime due to FRET between the donor and the acceptor can be monitored. Treatment with RNase before FRET-FLIM measurements allows determination of whether the POI associates with DNA and/or RNA. A step-by-step protocol is provided for sample preparation, data acquisition and analysis. We describe how to calibrate the equipment and include a tutorial explaining the use of the FLIM software. To illustrate our approach, we provide experimental procedures to detect the interaction between plant DNA and two proteins (the AeCRN13 effector from the oomycete Aphanomyces euteiches and the AtWRKY22 defensive transcription factor from Arabidopsis). This protocol allows the detection of protein-nucleic acid interactions in plant cells and can be completed in <2 d.

Demonstration of the lack of cytotoxicity of unmodified and folic acid modified graphene oxide quantum dots, and their application to fluorescence lifetime imaging of HaCaT cells.

PubMed

Goreham, Renee V; Schroeder, Kathryn L; Holmes, Amy; Bradley, Siobhan J; Nann, Thomas

2018-01-24

The authors describe the synthesis of water-soluble and fluorescent graphene oxide quantum dots via acid exfoliation of graphite nanoparticles. The resultant graphene oxide quantum dots (GoQDs) were then modified with folic acid. Folic acid receptors are overexpressed in cancer cells and hence can bind to functionalized graphene oxide quantum dots. On excitation at 305 nm, the GoQDs display green fluorescence with a peak wavelength at ~520 nm. The modified GoQDs are non-toxic to macrophage cells even after prolonged exposure and high concentrations. Fluorescence lifetime imaging and multiphoton microscopy was used (in combination) to image HeCaT cells exposed to GoQDs, resulting in a superior method for bioimaging. Graphical abstract Schematic representation of graphene oxide quantum dots, folic acid modified graphene oxide quantum dots (red), and the use of fluorescence lifetime to discriminate against green auto-fluorescence of HeCaT cells.

Genetically encoded fluorescent tags

PubMed Central

Thorn, Kurt

2017-01-01

Genetically encoded fluorescent tags are protein sequences that can be fused to a protein of interest to render it fluorescent. These tags have revolutionized cell biology by allowing nearly any protein to be imaged by light microscopy at submicrometer spatial resolution and subsecond time resolution in a live cell or organism. They can also be used to measure protein abundance in thousands to millions of cells using flow cytometry. Here I provide an introduction to the different genetic tags available, including both intrinsically fluorescent proteins and proteins that derive their fluorescence from binding of either endogenous or exogenous fluorophores. I discuss their optical and biological properties and guidelines for choosing appropriate tags for an experiment. Tools for tagging nucleic acid sequences and reporter molecules that detect the presence of different biomolecules are also briefly discussed. PMID:28360214

Unusual Fluorescent Responses of Morpholine-functionalized Fluorescent Probes to pH via Manipulation of BODIPY’s HOMO and LUMO Energy Orbitals for Intracellular pH Detection

PubMed Central

Zhang, Jingtuo; Yang, Mu; Mazi, Wafa; Adhikari, Kapil; Fang, Mingxi; Xie, Fei; Valenzano, Loredana; Tiwari, Ashutosh; Luo, Fen-Tair; Liu, Haiying

2016-01-01

Three uncommon morpholine-based fluorescent probes (A, B and C) for pH were prepared by introducing morpholine residues to BODIPY dyes at 4,4’- and 2,6-positions, respectively. In contrast to morpholine-based fluorescent probes for pH reported in literature, these fluorescent probes display high fluorescence in a basic condition while they exhibit very weak fluorescence in an acidic condition. The theoretical calculation confirmed that morpholine is unable to function as either an electron donor or an electron acceptor to quench the BODIPY fluorescence in the neutral and basic condition via photo-induced electron transfer (PET) mechanism because the LUMO energy of morpholine is higher than those of the BODIPY dyes while its HOMO energy is lower than those of the BODIPY dyes. However, the protonation of tertiary amines of the morpholine residues in an acidic environment leads to fluorescence quenching of the BODIPY dyes via d-PET mechanism. The fluorescence quenching is because the protonation effectively decreases the LUMO energy which locates between the HOMO and LUMO energies of the BODIPY dyes. Fluorescent probe C with deep-red emission has been successfully used to detect pH changes in mammalian cells. PMID:27547822

A label-free fluorescent aptamer sensor based on regulation of malachite green fluorescence

PubMed Central

Xu, Weichen; Lu, Yi

2009-01-01

We report a label-free fluorescent aptamer sensor for adenosine based on the regulation of malachite green (MG) fluorescence, with comparable sensitivity and selectivity to other labeled adenosine aptamer-based sensors. The sensor consists of free MG, an aptamer strand containing an adenosine aptamer next to an MG aptamer, and a bridging strand that partially hybridizes to the aptamer strand. Such a hybridization prevents MG from binding to MG aptamer, resulting in low fluorescence of MG in the absence of adenosine. Addition of adenosine causes the adenosine aptamer to bind adenosine, weakening the hybridization of the aptamer strand with the bridging strand, making it possible for MG to bind to the aptamer strand and exhibits high fluorescence intensity. Since this design is based purely on nucleic acid hybridization, it can be generally applied to other aptamers for the label-free detection of a broad range of analytes. PMID:20017558

Highly sensitive fluorescence quantitative detection of specific DNA sequences with molecular beacons and nucleic acid dye SYBR Green I.

PubMed

Xiang, Dongshan; Zhai, Kun; Xiang, Wenjun; Wang, Lianzhi

2014-11-01

A highly sensitive fluorescence method of quantitative detection for specific DNA sequence is developed based on molecular beacon (MB) and nucleic acid dye SYBR Green I by synchronous fluorescence analysis. It is demonstrated by an oligonucleotide sequence of wild-type HBV (target DNA) as a model system. In this strategy, the fluorophore of MB is designed to be 6-carboxyfluorescein group (FAM), and the maximum excitation wavelength and maximum emission wavelength are both very close to that of SYBR Green I. In the presence of targets DNA, the MBs hybridize with the targets DNA and form double-strand DNA (dsDNA), the fluorophore FAM is separated from the quencher BHQ-1, thus the fluorophore emit fluorescence. At the same time, SYBR Green I binds to dsDNA, the fluorescence intensity of SYBR Green I is significantly enhanced. When targets DNA are detected by synchronous fluorescence analysis, the fluorescence peaks of FAM and SYBR Green I overlap completely, so the fluorescence signal of system will be significantly enhanced. Thus, highly sensitive fluorescence quantitative detection for DNA can be realized. Under the optimum conditions, the total fluorescence intensity of FAM and SYBR Green I exhibits good linear dependence on concentration of targets DNA in the range from 2×10(-11) to 2.5×10(-9)M. The detection limit of target DNA is estimated to be 9×10(-12)M (3σ). Compared with previously reported methods of detection DNA with MB, the proposed method can significantly enhance the detection sensitivity. Copyright © 2014 Elsevier B.V. All rights reserved.

5-Aminolevulinic Acid-Protoporphyrin IX Fluorescence-Guided Surgery of High-Grade Gliomas: A Systematic Review.

PubMed

Guyotat, Jacques; Pallud, Johan; Armoiry, Xavier; Pavlov, Vladislav; Metellus, Philippe

2016-01-01

The current first-line treatment of malignant gliomas consists in surgical resection (if possible) as large as possible. The existing tools don't permit to identify the limits of tumor infiltration, which goes beyond the zone of contrast enhancement on MRI. The fluorescence-guided malignant gliomas surgery was started 15 years ago and had become a standard of care in many countries. The technique is based on fluorescent molecule revelation using the filters, positioned within the surgical microscope. The fluorophore, protoporphyrin IX (PpIX), is converted in tumoral cells from 5-aminolevulinic acid (5-ALA), given orally before surgery. Many studies have shown that the ratio of gross total resections was higher if the fluorescence technique was used. The fluorescence signal intensity is correlated to the cell density and the PpIX concentration. The current method has a very high specificity but still lower sensibility, particularly regarding the zones with poor tumoral infiltration. This book reviews the principles of the technique and the results (extent of resection and survival).

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.

Fast analysis of domoic acid using microchip electrophoresis with laser-induced fluorescence detection.

PubMed

Cheng, Yongqiang; Guo, Cuilian; Zhao, Bin; Yang, Li

2017-04-01

A fast and effective method was developed to detect domoic acid based upon microchip electrophoresis combined with laser-induced fluorescence detection. Through study of the gated injection process on the cross channel of the microchip, the low-voltage mode with relatively longer sample loading time was adopted to reduce the sample discrimination and improve the signal sensitivity. Fluorescein isothiocyanate was used as the derivatizing reagent for domoic acid. Under the optimized conditions, domoic acid was completely separated in 60 s with separation efficiency of 1.35 × 10 5  m -1 . The calibration curve was obtained in the range of 1.0 × 10 -9 to 1.0 × 10 -7  mol/L, and the detection limit reached 2.8 × 10 -10  mol/L. This developed method was successfully applied to analyze domoic acid in real samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design and synthesis of a novel lanthanide fluorescent probe (TbIII-dtpa-bis(2,6-diaminopurine)) and its application to the detection of uric acid in urine sample.

PubMed

Yang, Fan; Yu, Zhiyue; Li, Xinyi; Ren, Peipei; Liu, Guanhong; Song, Youtao; Wang, Jun

2018-06-03

In this study, a novel fluorescent probe, Tb III -dtpa-bis(2,6-diaminopurine) (Tb-dtpa-bdap), is designed based on the principle of complementary base pairing and synthesized for uric acid detection. The synthesized fluorescent probe is characterized by 1 H NMR, 13 C NMR, infra-red (IR) spectrum and ultraviolet-visible (UV-vis) spectra. It is found that the fluorescence of Tb-dtpa-bdap solution can be quenched obviously in the presence of uric acid. The affecting factors, including solution acidity, uric acid concentration and interfering substances, on the detection of uric acid using this probe are examined. Under optimized conditions, the fluorescence intensities of Tb-dtpa-bdap solution towards different uric acid concentrations show a linear response in the range from 1.00 × 10 -5  mol·L -1 to 5.00 × 10 -5  mol·L -1 with a linear correlation coefficient (R 2 ) of 0.9877. And the obtained limit of detection (LOD) is about 5.80 × 10 -6  mol·L -1 , which is lower than the level of uric acid in actual urine. The mechanism on the detection of uric acid by using Tb-dtpa-bdap is inferred from the experimental results. The facts demonstrate that the proposed fluorescent probe can be successfully applied for the determination of uric acid in human urine samples. Copyright © 2018 Elsevier B.V. All rights reserved.

[Effects of simulating acid rain on photosynthesis and chlorophyll fluorescence parameters of Quercus glauca Quercus glauca].

PubMed

Wang, Sai; Yi, Li-Ta; Yu, Shu-Quan; Zhang, Chao; Shi, Jing-Jing

2014-08-01

At three levels of simulated acid rainfall intensities with pH values of 2.5 (severe), 40 (medium) and 5.6 (light) respectively, the responses of chlorophyll fluorescence and photosynthetic parameters of Quercus glauca seedlings were studied in three acid rainfall treatments, i. e. only the aboveground of seedlings exposed to acid rain (T1), both of the seedlings and soil exposed to acid rain (T2), only the soil exposed to acid rain (T3) compared with blank control (CK). Under the severe acid rainfall, T1 significantly inhibited chlorophyll synthesis, and thus reduced the primary photochemical efficiency of PS II ( F(v)/F(m)), potential activity of PS II (F(v)/F(o)) , apparent quantum (Y), net photosynthetic rate (P(n)), and transpiration rate (T(r)), but increased the light compensation point (LCP) and dark respiration rate (R(d)) of Q. glauca seedlings. T2 inhibited, but T3 played a little enhancement on the aforementioned parameters of Q. glauca seedlings. Under the conditions of medium and light acid rainfall intensities, the above parameters in the three treatments were higher than that of CK, except with lower R(d). The chlorophyll fluorescence and photosynthetic parameters showed a similar tendency in the three treatments, i. e. T2>T3 >T1. It indicated that T1 had the strongest inhibition on seedlings in condition of the severe acid rainfall, while T2 had the most dramatic facilitating effect on seedlings under the medium and light acid rainfall. Intensity of acid rainfall had significant influences on SPAD, F(v)/F(m), F(v)/F(o), Y, P(n), T(r), and maximum photosynthetic rate (A(max)), whereas treatments of acid rainfall affected SPAD, F(v)/F(m), Y, P(n), T(r), A(max) and light saturation point (LSP). The interaction of acid rainfall intensities and treatments played significant effects on SPAD, F(v)/F(m), Y, P(n) and A(max).

Preparation of Au Nanoclusters-Modified Polylactic Acid Fiber with Bright Red Fluorescence and its Use as Sensing Probe.

PubMed

Zhu, Wenli; Li, Huili; Wan, Ajun; Liu, Lanbo

2017-01-01

In present work, the Au nanoclusters-modified polylactic acid fiber (PLA-Au NCs) with bright red fluorescence were fabricated by the encapsulation of Au nanoclusters (Au NCs) in the PLA fiber treated with H 2 O 2 . The Au 25 nanoclusters stabilized by bovine serum albumin (BSA-Au NCs) were prepared via an improved "green" synthetic routine. With pretreatment of the PLA fiber in H 2 O 2 concentration of 12 and 18 %, the as-prepared PLA-Au NCs exhibited brighter red emission with a strong peak centered at ~640 nm than BSA-Au NCs. The fluorescence can be quenched by nitric oxide (NO). A good linear relationship between the relative fluorescence quenching intensity of the as-prepared PLA-Au NCs and the concentration of NO can be obtained in the range of 0.0732 to 0.7320 mM, and the detection limit was 0.0070 mM.

Intraoperative confocal microscopy in the visualization of 5-aminolevulinic acid fluorescence in low-grade gliomas.

PubMed

Sanai, Nader; Snyder, Laura A; Honea, Norissa J; Coons, Stephen W; Eschbacher, Jennifer M; Smith, Kris A; Spetzler, Robert F

2011-10-01

Greater extent of resection (EOR) for patients with low-grade glioma (LGG) corresponds with improved clinical outcome, yet remains a central challenge to the neurosurgical oncologist. Although 5-aminolevulinic acid (5-ALA)-induced tumor fluorescence is a strategy that can improve EOR in gliomas, only glioblastomas routinely fluoresce following 5-ALA administration. Intraoperative confocal microscopy adapts conventional confocal technology to a handheld probe that provides real-time fluorescent imaging at up to 1000× magnification. The authors report a combined approach in which intraoperative confocal microscopy is used to visualize 5-ALA tumor fluorescence in LGGs during the course of microsurgical resection. Following 5-ALA administration, patients with newly diagnosed LGG underwent microsurgical resection. Intraoperative confocal microscopy was conducted at the following points: 1) initial encounter with the tumor; 2) the midpoint of tumor resection; and 3) the presumed brain-tumor interface. Histopathological analysis of these sites correlated tumor infiltration with intraoperative cellular tumor fluorescence. Ten consecutive patients with WHO Grades I and II gliomas underwent microsurgical resection with 5-ALA and intraoperative confocal microscopy. Macroscopic tumor fluorescence was not evident in any patient. However, in each case, intraoperative confocal microscopy identified tumor fluorescence at a cellular level, a finding that corresponded to tumor infiltration on matched histological analyses. Intraoperative confocal microscopy can visualize cellular 5-ALA-induced tumor fluorescence within LGGs and at the brain-tumor interface. To assess the clinical value of 5-ALA for high-grade gliomas in conjunction with neuronavigation, and for LGGs in combination with intraoperative confocal microscopy and neuronavigation, a Phase IIIa randomized placebo-controlled trial (BALANCE) is underway at the authors' institution.

Chromophore Isomer Stabilization Is Critical to the Efficient Fluorescence of Cyan Fluorescent Proteins.

PubMed

Gotthard, Guillaume; von Stetten, David; Clavel, Damien; Noirclerc-Savoye, Marjolaine; Royant, Antoine

2017-12-12

ECFP, the first usable cyan fluorescent protein (CFP), was obtained by adapting the tyrosine-based chromophore environment in green fluorescent protein to that of a tryptophan-based one. This first-generation CFP was superseded by the popular Cerulean, CyPet, and SCFP3A that were engineered by rational and random mutagenesis, yet the latter CFPs still exhibit suboptimal properties of pH sensitivity and reversible photobleaching behavior. These flaws were serendipitously corrected in the third-generation CFP mTurquoise and its successors without an obvious rationale. We show here that the evolution process had unexpectedly remodeled the chromophore environment in second-generation CFPs so they would accommodate a different isomer, whose formation is favored by acidic pH or light irradiation and which emits fluorescence much less efficiently. Our results illustrate how fluorescent protein engineering based solely on fluorescence efficiency optimization may affect other photophysical or physicochemical parameters and provide novel insights into the rational evolution of fluorescent proteins with a tryptophan-based chromophore.

[1,10]Phenanthroline based cyanine dyes as fluorescent probes for ribonucleic acids in live cells

NASA Astrophysics Data System (ADS)

Kovalska, Vladyslava; Kuperman, Marina; Varzatskii, Oleg; Kryvorotenko, Dmytro; Kinski, Elisa; Schikora, Margot; Janko, Christina; Alexiou, Christoph; Yarmoluk, Sergiy; Mokhir, Andriy

2017-12-01

A series of monomethine, trimethine- and styrylcyanine dyes based on a [1,10]phenanthroline moiety was synthesized, characterized and investigated as potential fluorescent probes for nucleic acids in cell free settings and in cells. The dyes were found to be weakly fluorescent in the unbound state, whereas upon the binding to dsDNA or RNA their emission intensity raised up to 50 times (for monomethine benzothiazole derivative FT1 complexed with RNA). The strongest fluorescence intensity in assemblies with dsDNA and RNA was observed for the trimethine benzothiazole derivative FT4. The quantum yield of FT4 fluorescence in its complex with dsDNA was found to be 1.5% and the binding constant (K b) was estimated to be 7.9 × 104 M-1 that is a typical value for intercalating molecules. The FT4 dye was found to be cell membrane permeable. It stains RNA rich components—the nucleoli and most probably the cytoplasmic RNA. FT4 bound to RNAs delivers a very strong fluorescence signal, which makes this easily accessible dye a potentially useful alternative to known RNA stains, e.g. expensive SYTO® 83. The advantage of FT4 is its easy synthetic access including no chromatographic purification steps, which will be reflected in its substantially lower price.

A rapid microwave synthesis of nitrogen-sulfur co-doped carbon nanodots as highly sensitive and selective fluorescence probes for ascorbic acid.

PubMed

Duan, Junxia; Yu, Jie; Feng, Suling; Su, Li

2016-06-01

A ultrafast one-step microwave-assisted method was developed for the synthesis of nitrogen-sulfur co-doped carbon nanodots (N,S-CDs) by using ethylenediamine as the carbon source and sulfamic acid as the surface passivation reagent. The morphology and the properties of N,S-CDs were explored by a series of techniques, such as high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis absorption and fluorescence spectroscopy. The prepared N,S-CDs exhibit bright blue photoluminescence with a high fluorescence quantum yield (FLQY) up to 28%, and high stability and excellent water solubility. A N,S-CDs-based fluorescent probe was developed for sensitive detection ascorbic acid (AA) in the presence of Cu(2+), based on the mechanism that AA reduces Cu(2+) to Cu(+), then Cu(+) quenches the fluorescence of N,S-CDs through electron or energy transfer due to the interaction between Cu(+) and thiol ligand on the N,S-CDs surface. The observed linear response concentration range was from 0.057 to 4.0μM to AA with a detection limit as low as 18nM. The probe exhibited a highly selective response toward AA even in the presence of possible interfering substances, such as uric acid and citric acid. Moreover, these promising features made the sensing system used for the analysis of human serum and urine samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Proton triggered emission and selective sensing of picric acid by the fluorescent aggregates of 6,7-dimethyl-2,3-bis-(2-pyridyl)-quinoxaline.

PubMed

Mazumdar, Prativa; Maity, Samir; Shyamal, Milan; Das, Debasish; Sahoo, Gobinda Prasad; Misra, Ajay

2016-03-14

A heteroatom containing organic fluorophore 6,7-dimethyl-2,3-bis-(2-pyridyl)-quinoxaline (BPQ) is weakly emissive in solution but its emission properties are highly enhanced in the aggregated state due to the restriction of intramolecular rotation (RIR) and large amplitude vibrational modes, demonstrating the phenomenon, aggregation induced emission enhancement (AIEE). It has strong proton capture capability, allowing reversible fluorescence switching in basic and acidic medium and the emission color changes from blue to green in the aggregated state through protonation. It has been explained as a competition between intramolecular charge transfers (ICTs) and the AIEE phenomena at a lower pH range (pH ∼1-4). Such behavior enables it as a fluorescent pH sensor for detection in acidic and basic medium. Morphologies of the particles are characterized using optical and field emission scanning electron microscopic (FESEM) studies. The turn off fluorescence properties of aggregated BPQ have been utilized for the selective detection of picric acid and the fluorescence quenching is explained due to ground state complexation with a strong quenching constant, 7.81 × 10(4) M(-1).

Time-resolved spectral studies of blue-green fluorescence of artichoke (Cynara cardunculus L. Var. Scolymus) leaves: identification of chlorogenic acid as one of the major fluorophores and age-mediated changes.

PubMed

Morales, Fermín; Cartelat, Aurélie; Alvarez-Fernández, Ana; Moya, Ismael; Cerovic, Zoran G

2005-12-14

Synchrotron radiation and the time-correlated single-photon counting technique were used to investigate the spectral and time-resolved characteristics of blue-green fluorescence (BGF) of artichoke leaves. Leaves emitted BGF under ultraviolet (UV) excitation; the abaxial side was much more fluorescent than the adaxial side, and in both cases, the youngest leaves were much more fluorescent than the oldest ones. The BGF of artichoke leaves was dominated by the presence of hydroxycinnamic acids. A decrease in the percentage of BGF attributable to the very short kinetic component (from 42 to 20%), in the shape of the BGF excitation spectra, and chlorogenic acid concentrations indicate that there is a loss of hydroxycinnamic acid with leaf age. Studies on excitation, emission, and synchronized fluorescence spectra of leaves and trichomes and chlorogenic acid contents indicate that chlorogenic acid is one of the main blue-green fluorophores in artichoke leaves. Results of the present study indicate that 20-42% (i.e., the very short kinetic component) of the overall BGF is emitted by chlorogenic acid. Time-resolved BGF measurements could be a means to extract information on chlorogenic acid fluorescence from the overall leaf BGF.

TRACE ANALYSIS OF FLUORESCEIN-DERIVATIZED PHENOXY ACID HERBICIDES BY MICELLAR ELECTROKINETIC CHROMATOGRAPHY WITH LASER-INDUCTED FLUORESCENCE DETECTION

EPA Science Inventory

Micellar electrokinetic chromatography (MEKC) with laser-induced fluorescence (LIF) detection was used for the trace analysis of phenoxy acid herbicides. Capillary electrophoresis (CE) with LIF detection, which has not previously been used for pesticide analysis, overcomes the po...

Ultrasensitive determination of jasmonic acid in plant tissues using high-performance liquid chromatography with fluorescence detection.

PubMed

Xiong, Xu-Jie; Rao, Wan-Bing; Guo, Xiao-Feng; Wang, Hong; Zhang, Hua-Shan

2012-05-23

An ultrasensitive and selective high-performance liquid chromatographic method for the volatile signaling hormone, jasmonic acid, has been developed based on precolumn derivatization with 1,3,5,7-tetramethyl-8-aminozide-difluoroboradiaza-s-indacene (BODIPY-aminozide). The derivatization reaction was carried out at 60 °C for 30 min in the presence of phosphoric acid. The formed jasmonic acid derivative was eluted using a mobile phase of methanol/pH 6.50 ammonium formate buffer/tetrahydrofuran (67:30:3, v/v/v) in 10 min on a C(18) column and detected with fluorescence detection at excitation and emission wavelengths of 495 and 505 nm, respectively. The detection limit (signal-to-noise ratio = 4) reached 1.14 × 10(-10) M or 2.29 fmol per injection (20 μL), which is the lowest of the existing methods. The proposed method has been successfully applied to the direct determination of trace jasmonic acid in the crude extracts of soybean leaves from soybean mosaic virus-infected and normal plants with recoveries of 95-104%.

Fluorescence, polarized fluorescence, and Brewster angle microscopy of palmitic acid and lung surfactant protein B monolayers.

PubMed Central

Lipp, M M; Lee, K Y; Waring, A; Zasadzinski, J A

1997-01-01

Fluorescence, polarized fluorescence, and Brewster angle microscopy reveal that human lung surfactant protein SP-B and its amino terminus (SP-B[1-25]) alter the phase behavior of palmitic acid monolayers by inhibiting the formation of condensed phases and creating a new fluid protein-rich phase. This fluid phase forms a network that separates condensed phase domains at coexistence and persists to high surface pressures. The network changes the monolayer collapse mechanism from heterogeneous nucleation/growth and fracturing processes to a more homogeneous process through isolating individual condensed phase domains. This results in higher surface pressures at collapse, and monolayers easier to respread on expansion, factors essential to the in vivo function of lung surfactant. The network is stabilized by a low-line tension between the coexisting phases, as confirmed by the observation of extended linear domains, or "stripe" phases, and a Gouy-Chapman analysis of protein-containing monolayers. Comparison of isotherm data and observed morphologies of monolayers containing SP-B(1-25) with those containing the full SP-B sequence show that the shortened peptide retains most of the native activity of the full-length protein, which may lead to cheaper and more effective synthetic replacement formulations. Images FIGURE 1 FIGURE 3 FIGURE 4 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 FIGURE 10 PMID:9168053

Rapid determination of nitrite in foods in acidic conditions by high-performance liquid chromatography with fluorescence detection.

PubMed

Wang, Xiao-Fang; Fan, Ji-Cai; Ren, Ren; Jin, Quan; Wang, Jing

2016-06-01

In this study, a simple, rapid, and sensitive method for the determination of nitrite (NO2 (-) ) in food samples by high-performance liquid chromatography with fluorescence detection in acidic conditions had been developed. The derivatization of the nitrite with 2,3-diaminonaphthalene was performed in acidic conditions to yield the highly fluorescent 2,3-naphthotriazole, which was directly analyzed by high-performance liquid chromatography with fluorescence detection without adjusting the solution to alkaline. The analysis column was reversed-phase C8 column. A constant flow rate of 1.0 mL/min was employed using water/acetonitrile as the mobile phase in isocratic mode (70:30, v/v). Fluorescence was monitored with excitation at 375 nm and emission at 415 nm. The standard calibration curves were linear for nitrite in different matrixes in the concentration range of 0-100 μg/L, and the correlation coefficients ranged from 0.9978 to 0.9998. The limits of detection and quantification were in the ranges of 0.012-0.060 and 0.040-0.20 mg/kg, respectively. The recoveries of nitrite from samples spiked at three different concentrations were 74.0-113.2%, and the relative standard deviations of the recovery results (n = 6) were 1.67-10.8%. The proposed method has good repeatability and is very sensitive and simple. It has been successfully used to determine nitrite in foods. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

pH-Mediated Fluorescent Polymer Particles and Gel from Hyperbranched Polyethylenimine and the Mechanism of Intrinsic Fluorescence.

PubMed

Liu, Shi Gang; Li, Na; Ling, Yu; Kang, Bei Hua; Geng, Shuo; Li, Nian Bing; Luo, Hong Qun

2016-02-23

We report that fluorescence properties and morphology of hyperbranched polyethylenimine (hPEI) cross-linked with formaldehyde are highly dependent on the pH values of the cross-linking reaction. Under acidic and neutral conditions, water-soluble fluorescent copolymer particles (CPs) were produced. However, under basic conditions, white gels with weak fluorescence emission would be obtained. The water-soluble hPEI-formaldehyde (hPEI-F) CPs show strong intrinsic fluorescence without the conjugation to any classical fluorescent agents. By the combination of spectroscopy and microscopy techniques, the mechanism of fluorescence emission was discussed. We propose that the intrinsic fluorescence originates from the formation of a Schiff base in the cross-linking process between hPEI and formaldehyde. Schiff base bonds are the fluorescence-emitting moieties, and the compact structure of hPEI-F CPs plays an important role in their strong fluorescence emission. The exploration on fluorescence mechanism may provide a new strategy to prepare fluorescent polymer particles. In addition, the investigation shows that the hPEI-F CPs hold potential as a fluorescent probe for the detection of copper ions in aqueous media.

Fluorescence-guided resection with 5-aminolevulinic Acid of subependymomas of the fourth ventricle: report of 2 cases: technical case report.

PubMed

Bernal García, Luis Miguel; Cabezudo Artero, José Manuel; Marcelo Zamorano, María Bella; Gilete Tejero, Ignacio

2015-06-01

The usefulness of 5-aminolevulinic acid (5-ALA) for resection of malignant astrocytomas has been established in recent years. In addition to these tumors, it has been reported that 5-ALA fluorescence could be elicited in other tumors such as intracranial and spinal meningiomas or posterior fossa and spinal cord ependymomas, resulting in improved resections. Here, we present 2 cases of subependymomas of the fourth ventricle that showed intense fluorescence after 5-ALA administration. To the best of our knowledge, these are the first reported cases of subependymomas in this location in which 5-ALA elicited useful fluorescence. Case 1 was a 61-year-old woman with a history of headaches accompanied by vomiting in the last month. Magnetic resonance imaging (MRI) revealed a tumor occupying the fourth ventricle with slight irregular enhancement. She was operated on after administration of 5-ALA. The tumor emitted intense red fluorescence when illuminated with blue light. An MRI performed 48 hours after surgery confirmed complete resection of the tumor. The pathological diagnosis was subependymoma. Case 2 was a 35-year-old man with a history of several months of headaches and vomiting. An MRI revealed a tumor occupying the caudal part of the fourth ventricle with moderate and irregular enhancement. He was operated on after administration of 5-ALA. The tumor showed intense fluorescence. An MRI performed 48 hours after surgery confirmed a complete resection of the tumor. The pathological diagnosis was subependymoma. Fluorescence-guided resection with 5-ALA may be useful for resection of subependymomas of the fourth ventricle. However, further studies are needed.

Lead discovery for mammalian elongation of long chain fatty acids family 6 using a combination of high-throughput fluorescent-based assay and RapidFire mass spectrometry assay

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

Takamiya, Mari; Discovery Technology Laboratories, Sohyaku, Innovative Research Division, Mitsubishi Tanabe Pharma Corporation, Kawagishi, Toda-shi, Saitama; Sakurai, Masaaki

A high-throughput RapidFire mass spectrometry assay is described for elongation of very long-chain fatty acids family 6 (Elovl6). Elovl6 is a microsomal enzyme that regulates the elongation of C12-16 saturated and monounsaturated fatty acids. Elovl6 may be a new therapeutic target for fat metabolism disorders such as obesity, type 2 diabetes, and nonalcoholic steatohepatitis. To identify new Elovl6 inhibitors, we developed a high-throughput fluorescence screening assay in 1536-well format. However, a number of false positives caused by fluorescent interference have been identified. To pick up the real active compounds among the primary hits from the fluorescence assay, we developed amore » RapidFire mass spectrometry assay and a conventional radioisotope assay. These assays have the advantage of detecting the main products directly without using fluorescent-labeled substrates. As a result, 276 compounds (30%) of the primary hits (921 compounds) in a fluorescence ultra-high-throughput screening method were identified as common active compounds in these two assays. It is concluded that both methods are very effective to eliminate false positives. Compared with the radioisotope method using an expensive {sup 14}C-labeled substrate, the RapidFire mass spectrometry method using unlabeled substrates is a high-accuracy, high-throughput method. In addition, some of the hit compounds selected from the screening inhibited cellular fatty acid elongation in HEK293 cells expressing Elovl6 transiently. This result suggests that these compounds may be promising lead candidates for therapeutic drugs. Ultra-high-throughput fluorescence screening followed by a RapidFire mass spectrometry assay was a suitable strategy for lead discovery against Elovl6. - Highlights: • A novel assay for elongation of very-long-chain fatty acids 6 (Elovl6) is proposed. • RapidFire mass spectrometry (RF-MS) assay is useful to select real screening hits. • RF-MS assay is proved to be beneficial

Impact of fluorescent lighting on the browning potential of model wine solutions containing organic acids and iron.

PubMed

Grant-Preece, Paris; Barril, Celia; Schmidtke, Leigh M; Clark, Andrew C

2018-03-15

Model wine solutions containing organic acids, individually or combined, and iron(III), were exposed to light from fluorescent lamps or stored in darkness for four hours. (-)-Epicatechin was then added, and the solutions incubated in darkness for 10days. Browning was monitored by UV-visible absorption spectrophotometry and UHPLC-DAD. The pre-irradiated solutions containing tartaric acid exhibited increased yellow/brown coloration compared to the dark controls mainly due to reaction of the tartaric acid photodegradation product glyoxylic acid with (-)-epicatechin to form xanthylium cation pigments. In these solutions, browning decreased as the concentrations of organic acids other than tartaric acid increased. Xanthylium cations were also detected in the pre-irradiated malic acid solution. However, in the malic acid, succinic acid, citric acid and lactic acid solutions, any coloration was mainly due to the production of dehydrodiepicatechin A, which was largely independent of prior light exposure, but strongly affected by the organic acid present. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of flavin-based fluorescent proteins: an emerging class of fluorescent reporters.

PubMed

Mukherjee, Arnab; Walker, Joshua; Weyant, Kevin B; Schroeder, Charles M

2013-01-01

Fluorescent reporter proteins based on flavin-binding photosensors were recently developed as a new class of genetically encoded probes characterized by small size and oxygen-independent maturation of fluorescence. Flavin-based fluorescent proteins (FbFPs) address two major limitations associated with existing fluorescent reporters derived from the green fluorescent protein (GFP)-namely, the overall large size and oxygen-dependent maturation of fluorescence of GFP. However, FbFPs are at a nascent stage of development and have been utilized in only a handful of biological studies. Importantly, a full understanding of the performance and properties of FbFPs as a practical set of biological probes is lacking. In this work, we extensively characterize three FbFPs isolated from Pseudomonas putida, Bacillus subtilis, and Arabidopsis thaliana, using in vitro studies to assess probe brightness, oligomeric state, maturation time, fraction of fluorescent holoprotein, pH tolerance, redox sensitivity, and thermal stability. Furthermore, we validate FbFPs as stable molecular tags using in vivo studies by constructing a series of FbFP-based transcriptional constructs to probe promoter activity in Escherichia coli. Overall, FbFPs show key advantages as broad-spectrum biological reporters including robust pH tolerance (4-11), thermal stability (up to 60°C), and rapid maturation of fluorescence (<3 min.). In addition, the FbFP derived from Arabidopsis thaliana (iLOV) emerged as a stable and nonperturbative reporter of promoter activity in Escherichia coli. Our results demonstrate that FbFP-based reporters have the potential to address key limitations associated with the use of GFP, such as pH-sensitive fluorescence and slow kinetics of fluorescence maturation (10-40 minutes for half maximal fluorescence recovery). From this view, FbFPs represent a useful new addition to the fluorescent reporter protein palette, and our results constitute an important framework to enable

Micelle-induced versatile sensing behavior of bispyrene-based fluorescent molecular sensor for picric acid and PYX explosives.

PubMed

Ding, Liping; Bai, Yumei; Cao, Yuan; Ren, Guijia; Blanchard, Gary J; Fang, Yu

2014-07-08

The effect of surfactant micelles on the photophysical properties of a cationic bispyrene fluorophore, Py-diIM-Py, was systemically examined. The results from series of measurements including UV-vis absorption, steady-state fluorescence emission, quantum yield, fluorescence lifetime, and time-resolved emission spectra reveal that the cationic fluorophore is only encapsulated by the anionic sodium dodecyl sulfate (SDS) surfactant micelles and not incorporated in the cationic dodecyltrimethylammonium bromide (DTAB) and neutral Triton X-100 (TX100) surfactant micelles. This different fluorophore location in the micellar solutions significantly influences its sensing behavior to various explosives. Fluorescence quenching studies reveal that the simple variation of micellar systems leads to significant changes in the sensitivity and selectivity of the fluorescent sensor to explosives. The sensor exhibits an on-off response to multiple explosives with the highest sensitivity to picric acid (PA) in the anionic SDS micelles. In the cationic DTAB micelles, it displays the highest on-off responses to PYX. Both the sensitivity and selectivity to PYX in the cationic micelles are enhanced compared with that to PA in the anionic micelles. However, the poor encapsulation in the neutral surfactant TX100 micelles leads to fluorescence instability of the fluorophore and fails to function as a sensor system. Time-resolved fluorescence decays in the presence of explosives reveal that the quenching mechanism of two micellar sensor systems to explosives is static in nature. The present work demonstrates that the electrostatic interaction between the cationic fluorophore and differently charged micelles plays a determinative role in adjusting its distribution in micellar solutions, which further influences the sensing behavior of the obtained micellar sensor systems.

Interconversion of Anthozoa GFP-like fluorescent and non-fluorescent proteins by mutagenesis

PubMed Central

Bulina, Maria E; Chudakov, Dmitry M; Mudrik, Nikolay N; Lukyanov, Konstantin A

2002-01-01

Background Within the family of green fluorescent protein (GFP) homologs, one can mark two main groups, specifically, fluorescent proteins (FPs) and non-fluorescent or chromoproteins (CPs). Structural background of differences between FPs and CPs are poorly understood to date. Results Here, we applied site-directed and random mutagenesis in order to to transform CP into FP and vice versa. A purple chromoprotein asCP (asFP595) from Anemonia sulcata and a red fluorescent protein DsRed from Discosoma sp. were selected as representatives of CPs and FPs, respectively. For asCP, some substitutions at positions 148 and 165 (numbering in accordance to GFP) were found to dramatically increase quantum yield of red fluorescence. For DsRed, substitutions at positions 148, 165, 167, and 203 significantly decreased fluorescence intensity, so that the spectral characteristics of these mutants became more close to those of CPs. Finally, a practically non-fluorescent mutant DsRed-NF was generated. This mutant carried four amino acid substitutions, specifically, S148C, I165N, K167M, and S203A. DsRed-NF possessed a high extinction coefficient and an extremely low quantum yield (< 0.001). These spectral characteristics allow one to regard DsRed-NF as a true chromoprotein. Conclusions We located a novel point in asCP sequence (position 165) mutations at which can result in red fluorescence appearance. Probably, this finding could be applied onto other CPs to generate red and far-red fluorescent mutants. A possibility to transform an FP into CP was demonstrated. Key role of residues adjacent to chromophore's phenolic ring in fluorescent/non-fluorescent states determination was revealed. PMID:11972899

Two-photon imaging of formaldehyde in live cells and animals utilizing a lysosome-targetable and acidic pH-activatable fluorescent probe.

PubMed

Xie, Xilei; Tang, Fuyan; Shangguan, Xiaoyan; Che, Shiyi; Niu, Jinye; Xiao, Yongsheng; Wang, Xu; Tang, Bo

2017-06-13

Lyso-TPFP presents lysosomal targetability and an acidic pH-activatable response toward formaldehyde. Thus, it exclusively visualizes lysosomal formaldehyde and is immune against it in neutral cytosol and other organelles. In addition, two-photon fluorescence imaging endows Lyso-TPFP with the capability of in situ tracking formaldehyde in live cells and animals.

An intramolecular charge transfer process based fluorescent probe for monitoring subtle pH fluctuation in living cells.

PubMed

Sun, Mingtai; Du, Libo; Yu, Huan; Zhang, Kui; Liu, Yang; Wang, Suhua

2017-01-01

It is crucial to monitor intracellular pH values and their fluctuation since the organelles of cells have different pH distribution. Herein we construct a new small molecule fluorescent probe HBT-O for monitoring the subtle pH values within the scope of neutral to acid in living cells. The probe exhibited good water solubility, a marked turquoise to olivine emission color change in response to pH, and tremendous fluorescence hypochromatic shift of ∼50nm (1718cm -1 ) as well as the increased fluorescence intensity when the pH value changed from neutral to acid. Thus, the probe HBT-O can distinguish the subtle changes in the range of normal pH values from neutral to acid with significant fluorescence changes. These properties can be attributed to the intramolecular charge transfer (ICT) process of the probe upon protonation in buffer solutions at varied pH values. Moreover, the probe was reversible and nearly non-toxic for living cells. Then the probe was successfully used to detect pH fluctuation in living cells by exhibiting different fluorescence colors and intensity. These findings demonstrate that the probe will find useful applications in biology and biomedical research. Copyright © 2016 Elsevier B.V. All rights reserved.

Benzimidazole derivatives: selective fluorescent chemosensors for the picogram detection of picric acid.

PubMed

Xiong, Jin-Feng; Li, Jian-Xiao; Mo, Guang-Zhen; Huo, Jing-Pei; Liu, Jin-Yan; Chen, Xiao-Yun; Wang, Zhao-Yang

2014-12-05

1,3,5-Tri(1H-benzo[d]imidazol-2-yl)benzene derivatives, as a new kind of fluorescent chemosensor for the detection of nitroaromatic explosives, are designed and synthesized by simple N-hydrocarbylation. Among 16 obtained compounds, compound 4g has the best capability for detection of picric acid (PA), having good selectivity and high sensitivity. The detection of PA with 4g solution-coated paper strips at the picogram level is developed. A simple, portable, and low-cost method is provided for detecting PA in solution and contact mode.

LASER BIOLOGY AND MEDICINE: Application of laser fluorimetry for determining the influence of a single amino-acid substitution on the individual photophysical parameters of a fluorescent form of a fluorescent protein mRFP1

NASA Astrophysics Data System (ADS)

Banishev, A. A.; Vrzheshch, E. P.; Shirshin, E. A.

2009-03-01

Individual photophysical parameters of the chromophore of a fluorescent protein mRFP1 and its two mutants (amino-acid substitution at position 66 - mRFP1/ Q66C and mRFP1/Q66S proteins) are determined. For this purpose, apart from conventional methods of fluorimetry and spectrophotometry, nonlinear laser fluorimetry is used. It is shown that the individual extinction coefficients of the chromophore of proteins correlate (correlation coefficient above 0.9) with the volume of the substituted amino-acid residue at position 66 (similar to the positions of the absorption, fluorescence excitation and emission maxima).

Gold nanocluster-based ratiometric fluorescent probes for hydrogen peroxide and enzymatic sensing of uric acid.

PubMed

Yang, Dongqin; Luo, Minchuan; Di, Junwei; Tu, Yifeng; Yan, Jilin

2018-05-18

A method is described for ratiometric fluorometric assays of H 2 O 2  by using two probes that have distinct response profiles. Under the catalytic action of ferrous ion, the 615 nm emission of protein-stabilized gold nanoclusters (under 365 nm photoexcitation) is quenched by H 2 O 2 , while an increased signal is generated with a peak at 450 nm by oxidizing coumarin with the H 2 O 2 /Fe(II) system to form a blue emitting fluorophore. These decrease/increase responses give a ratiometric signal. The ratio of the fluorescences at the two peaks are linearly related to the concentration of H 2 O 2 in the range from 0.05 to 10 μM, with a 7.7 nM limit of detection. The detection scheme was further coupled to the urate oxidase catalyzed oxidation of uric acid which proceeds under the formation of H 2 O 2 . This method provides an simple and effective means for the construction of ratiometric fluorometric (enzymatic) assays that involve the detection of H 2 O 2 . Graphical abstract Under catalysis by ferrous ion, hydrogen peroxide quenches the luminescence of gold nanoclusters (AuNCs) and oxidizes coumarin into a fluorescent derivative, which rendered fluorescence ON and OFF at two distinct wavelengths for ratiometric measurements.

Electronic structures and spectra of two antioxidants: uric acid and ascorbic acid

NASA Astrophysics Data System (ADS)

Shukla, M. K.; Mishra, P. C.

1996-04-01

Electronic absorption and fluorescence spectra of aqueous solutions of two well known antioxidants, uric acid and ascorbic acid (vitamin C), have been studied at different pH. The observed spectra have been interpreted in terms of neutral and anionic forms of the molecules with the help of molecular orbital calculations. The N 3 site of uric acid has been shown to be the most acidic. Fluorescence of uric acid seems to originate from an anion of the molecule in a wide pH range. Around pH 3, both the neutral and anionic forms of ascorbic acid appear to be present in aqueous solutions. In aqueous media, ascorbic acid appears to get converted easily to its dehydro form and this conversion does not seem to be reversible. An anion of dehydroascorbic acid seems to be formed on heating dehydroascorbic acid in aqueous solutions.

[Effects of acid rain stress on Eleocarpus glabripetalus seedlings leaf chlorophyll fluorescence characteristics and growth].

PubMed

Yin, Xiu-Min; Yu, Shu-Quan; Jiang, Hong; Liu, Mei-Hu

2010-06-01

A pot experiment was conducted to study the Eleocarpus glabripetalus seedlings leaf chlorophyll fluorescence characteristics and growth in different seasons under simulated acid rain stress (heavy, pH = 2. 5; moderate, pH = 4.0; and control, pH = 5.6). In the same treatments, the leaf relative chlorophyll content (SPAD), maximum PS II photochemical efficiency (F(v)/F(m)), actual PSII photochemical quantum yield (phi(PS II)), plant height, and stem diameter in different seasons were all in the order of October > July > April > January. In the same seasons, all the parameters were in the order of heavy acid rain > moderate acid rain > control. The interactions between different acid rain stress and seasons showed significant effects on the SPAD, F(v)/F(m), plant height, and stem diameter, but lesser effects on phi(PS II), qp and qN.

Construction of a 'turn-on' fluorescent probe system for His-tagged proteins.

PubMed

Murata, Atsushi; Arai, Satoshi; Yoon, Su-In; Takabayashi, Masao; Ozaki, Miwako; Takeoka, Shinji

2010-12-01

Hexahistidine ((His)(6)) tags are used to purify genetically engineered proteins. Herein, we describe the construction of a 'turn-on' fluorescent probe system that consists of the fluorescence quencher, Dabcyl, conjugated to (His)(6), and fluorescent tetramethylrhodamine conjugated to nitrilotriacetic acid, which, in the presence of Ni(2+), can bind (His)(6). The system is turned off when Dabcyl-(His)(6) is bound to the fluorescent nitrilotriacetic acid derivative. The binding strength of this system was assessed using electrospray ionization mass spectrometry, fluorescence correlation spectroscopy, and fluorescence intensity distribution analysis-polarization. Although there was no significant enhancement in fluorescence after addition of an equimolar amount of ubiquitin, the fluorescence increased from 14% to 40% of its initial intensity when an equimolar amount of (His)(6)-ubiquitin was added. Therefore, this system should be able to specifically recognize (His)(6)-proteins with good resolution and has the additional advantage that a washing step is not required to remove fluorescent probe, that is, not bound to the (His)(6)-protein. Copyright © 2010 Elsevier Ltd. All rights reserved.

A highly selective fluorescent probe for the detection of hypochlorous acid in tap water and living cells.

PubMed

Wang, Xiao; Zhou, Yanmei; Xu, Chenggong; Song, Haohan; Li, Li; Zhang, Junli; Guo, Meixia

2018-06-03

A turn-on fluorescent probe (DAME) for sensing hypochlorous acid (HClO) with excellent selectivity was presented. The fluorescent probe was composed of coumarin derivative as the fluorophore and dimethylcarbamothioic chloride group with a sulfide moiety as modulator. Additionally, the sulfide moiety would be oxidized by HClO, and then free dye of coumarin derivate was released and exhibited significant fluorescence. In addition, the probe could respond to HClO in solutions within 60 s and the limit of detection was down to 34.75 nM. Moreover, the probe was used for the detection of HClO in tap water through the home-made test paper. And confocal images confirmed that probe DAME could be used for recognizing HClO in living cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Intrinsically Labeled Fluorescent Oligonucleotide Probes on Quantum Dots for Transduction of Nucleic Acid Hybridization.

PubMed

Shahmuradyan, Anna; Krull, Ulrich J

2016-03-15

Quantum dots (QDs) have been widely used in chemical and biosensing due to their unique photoelectrical properties and are well suited as donors in fluorescence resonance energy transfer (FRET). Selective hybridization interactions of oligonucleotides on QDs have been determined by FRET. Typically, the QD-FRET constructs have made use of labeled targets or have implemented labeled sandwich format assays to introduce dyes in proximity to the QDs for the FRET process. The intention of this new work is to explore a method to incorporate the acceptor dye into the probe molecule. Thiazole orange (TO) derivatives are fluorescent intercalating dyes that have been used for detection of double-stranded nucleic acids. One such dye system has been reported in which single-stranded oligonucleotide probes were doubly labeled with adjacent thiazole orange derivatives. In the absence of the fully complementary (FC) oligonucleotide target, the dyes form an H-aggregate, which results in quenching of fluorescence emission due to excitonic interactions between the dyes. The hybridization of the FC target to the probe provides for dissociation of the aggregate as the dyes intercalate into the double stranded duplex, resulting in increased fluorescence. This work reports investigation of the dependence of the ratiometric signal on the type of linkage used to conjugate the dyes to the probe, the location of the dye along the length of the probe, and the distance between adjacent dye molecules. The limit of detection for 34mer and 90mer targets was found to be identical and was 10 nM (2 pmol), similar to analogous QD-FRET using labeled oligonucleotide target. The detection system could discriminate a one base pair mismatch (1BPM) target and was functional without substantial compromise of the signal in 75% serum. The 1BPM was found to reduce background signal, indicating that the structure of the mismatch affected the environment of the intercalating dyes.

Dual-labeling with 5-aminolevulinic acid and fluorescein for fluorescence-guided resection of high-grade gliomas: technical note.

PubMed

Suero Molina, Eric; Wölfer, Johannes; Ewelt, Christian; Ehrhardt, André; Brokinkel, Benjamin; Stummer, Walter

2018-02-01

OBJECTIVE Fluorescence guidance with 5-aminolevulinic acid (5-ALA) helps improve resections of malignant gliomas. However, one limitation is the low intensity of blue light for background illumination. Fluorescein has recently been reintroduced into neurosurgery, and novel microscope systems are available for visualizing this fluorochrome, which highlights all perfused tissues but has limited selectivity for tumor detection. Here, the authors investigate a combination of both fluorochromes: 5-ALA for distinguishing tumor and fluorescein for providing tissue fluorescence of adjacent brain tissue. METHODS The authors evaluated 6 patients who harbored cerebral lesions suggestive of high-grade glioma. Patients received 5-ALA (20 mg/kg) orally 4 hours before induction of anesthesia. Low-dose fluorescein (3 mg/kg intravenous) was injected immediately after anesthesia induction. Pentero microscopes (equipped either with Yellow 560 or Blue 400 filters) were used to visualize fluorescence. To simultaneously visualize both fluorochromes, the Yellow 560 module was combined with external blue light illumination (D-light C System). RESULTS Fluorescein-induced fluorescence created a useful background for protoporphyrin IX (PPIX) fluorescence, which appeared orange to red, surrounded by greenly fluorescent normal brain and edematous tissue. Green brain-tissue fluorescence was helpful in augmenting background. Levels of blue illumination that were too strong obscured PPIX fluorescence. Unspecific extravasation of fluorescein was noted at resection margins, which did not interfere with PPIX fluorescence detection. CONCLUSIONS Dual labeling with both PPIX and fluorescein fluorescence is feasible and gives superior background information during fluorescence-guided resections. The authors believe that this technique carries potential as a next step in fluorescence-guided resections if it is completely integrated into the surgical microscope.

Interfacial transduction of nucleic acid hybridization using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Algar, W Russ; Krull, Ulrich J

2009-01-06

Fluorescence resonance energy transfer (FRET) using immobilized quantum dots (QDs) as energy donors was explored as a transduction method for the detection of nucleic acid hybridization at an interface. This research was motivated by the success of the QD-FRET-based transduction of nucleic acid hybridization in solution-phase assays. This new work represents a fundamental step toward the assembly of a biosensor, where immobilization of the selective chemistry on a surface is desired. After immobilizing QD-probe oligonucleotide conjugates on optical fibers, a demonstration of the retention of selectivity was achieved by the introduction of acceptor (Cy3)-labeled single-stranded target oligonucleotides. Hybridization generated the proximity required for FRET, and the resulting fluorescence spectra provided an analytical signal proportional to the amount of target. This research provides an important framework for the future development of nucleic acid biosensors based on QDs and FRET. The most important findings of this work are that (1) a QD-FRET solid-phase hybridization assay is viable and (2) a passivating layer of denatured bovine serum albumin alleviates nonspecific adsorption, ultimately resulting in (3) the potential for a reusable assay format and mismatch discrimination. In this, the first incarnation of a solid-phase QD-FRET hybridization assay, the limit of detection was found to be 5 nM, and the dynamic range was almost 2 orders of magnitude. Selective discrimination of the target was shown using a three-base-pairs mismatch from a fully complementary sequence. Despite a gradual loss of signal, reuse of the optical fibers over multiple cycles of hybridization and dehybridization was possible. Directions for further improvement of the analytical performance by optimizing the design of the QD-probe oligonucleotide interface are identified.

The Value of 5-Aminolevulinic Acid in Low-grade Gliomas and High-grade Gliomas Lacking Glioblastoma Imaging Features: An Analysis Based on Fluorescence, Magnetic Resonance Imaging, 18F-Fluoroethyl Tyrosine Positron Emission Tomography, and Tumor Molecular Factors

PubMed Central

Jaber, Mohammed; Wölfer, Johannes; Ewelt, Christian; Holling, Markus; Hasselblatt, Martin; Niederstadt, Thomas; Zoubi, Tarek; Weckesser, Matthias

2015-01-01

BACKGROUND: Approximately 20% of grade II and most grade III gliomas fluoresce after 5-aminolevulinic acid (5-ALA) application. Conversely, approximately 30% of nonenhancing gliomas are actually high grade. OBJECTIVE: The aim of this study was to identify preoperative factors (ie, age, enhancement, 18F-fluoroethyl tyrosine positron emission tomography [18F-FET PET] uptake ratios) for predicting fluorescence in gliomas without typical glioblastomas imaging features and to determine whether fluorescence will allow prediction of tumor grade or molecular characteristics. METHODS: Patients harboring gliomas without typical glioblastoma imaging features were given 5-ALA. Fluorescence was recorded intraoperatively, and biopsy specimens collected from fluorescing tissue. World Health Organization (WHO) grade, Ki-67/MIB-1 index, IDH1 (R132H) mutation status, O6-methylguanine DNA methyltransferase (MGMT) promoter methylation status, and 1p/19q co-deletion status were assessed. Predictive factors for fluorescence were derived from preoperative magnetic resonance imaging and 18F-FET PET. Classification and regression tree analysis and receiver-operating-characteristic curves were generated for defining predictors. RESULTS: Of 166 tumors, 82 were diagnosed as WHO grade II, 76 as grade III, and 8 as glioblastomas grade IV. Contrast enhancement, tumor volume, and 18F-FET PET uptake ratio >1.85 predicted fluorescence. Fluorescence correlated with WHO grade (P < .001) and Ki-67/MIB-1 index (P < .001), but not with MGMT promoter methylation status, IDH1 mutation status, or 1p19q co-deletion status. The Ki-67/MIB-1 index in fluorescing grade III gliomas was higher than in nonfluorescing tumors, whereas in fluorescing and nonfluorescing grade II tumors, no differences were noted. CONCLUSION: Age, tumor volume, and 18F-FET PET uptake are factors predicting 5-ALA-induced fluorescence in gliomas without typical glioblastoma imaging features. Fluorescence was associated with an increased

Double-excitation fluorescence spectral imaging: eliminating tissue auto-fluorescence from in vivo PPIX measurements

NASA Astrophysics Data System (ADS)

Torosean, Sason; Flynn, Brendan; Samkoe, Kimberley S.; Davis, Scott C.; Gunn, Jason; Axelsson, Johan; Pogue, Brian W.

2012-02-01

An ultrasound coupled handheld-probe-based optical fluorescence molecular tomography (FMT) system has been in development for the purpose of quantifying the production of Protoporphyrin IX (PPIX) in aminolevulinic acid treated (ALA), Basal Cell Carcinoma (BCC) in vivo. The design couples fiber-based spectral sampling of PPIX fluorescence emission with a high frequency ultrasound imaging system, allowing regionally localized fluorescence intensities to be quantified [1]. The optical data are obtained by sequential excitation of the tissue with a 633nm laser, at four source locations and five parallel detections at each of the five interspersed detection locations. This method of acquisition permits fluorescence detection for both superficial and deep locations in ultrasound field. The optical boundary data, tissue layers segmented from ultrasound image and diffusion theory are used to estimate the fluorescence in tissue layers. To improve the recovery of the fluorescence signal of PPIX, eliminating tissue autofluorescence is of great importance. Here the approach was to utilize measurements which straddled the steep Qband excitation peak of PPIX, via the integration of an additional laser source, exciting at 637 nm; a wavelength with a 2 fold lower PPIX excitation value than 633nm.The auto-fluorescence spectrum acquired from the 637 nm laser is then used to spectrally decouple the fluorescence data and produce an accurate fluorescence emission signal, because the two wavelengths have very similar auto-fluorescence but substantially different PPIX excitation levels. The accuracy of this method, using a single source detector pair setup, is verified through animal tumor model experiments, and the result is compared to different methods of fluorescence signal recovery.

Synthesis and Evaluation of Aryl Boronic Acids as Fluorescent Artificial Receptors for Biological Carbohydrates

PubMed Central

Craig, Sandra

2011-01-01

Carbohydrates in various forms play a vital role in numerous critical biological processes. The detection of such saccharides can give insight into the progression of such diseases such as cancer. Boronic acids react with 1,2 and 1,3 diols of saccharides in non-aqueous or basic aqueous media. Herein, we describe the design, synthesis and evaluation of three bisboronic acid fluorescent probes, each having about ten linear steps in its synthesis. Among these compounds that were evaluated, 9b was shown to selectively label HepG2, liver carcinoma cell line within a concentration range of 0.5–10 μM in comparison to COS-7, a normal fibroblast cell line. PMID:22177855

Spectroscopic quantification of 5-hydroxymethylcytosine in genomic DNA using boric acid-functionalized nano-microsphere fluorescent probes.

PubMed

Chen, Hua-Yan; Wei, Jing-Ru; Pan, Jiong-Xiu; Zhang, Wei; Dang, Fu-Quan; Zhang, Zhi-Qi; Zhang, Jing

2017-05-15

5-hydroxymethylcytosine (5hmC) is the sixth base of DNA. It is involved in active DNA demethylation and can be a marker of diseases such as cancer. In this study, we developed a simple and sensitive 2-(4-boronophenyl)quinoline-4-carboxylic acid modified poly (glycidyl methacrylate (PBAQA-PGMA) fluorescent probe to detect the 5hmC content of genomic DNA based on T4 β-glucosyltransferase-catalyzed glucosylation of 5hmC. The fluorescence-enhanced intensity recorded from the DNA sample was proportional to its 5-hydroxymethylcytosine content and could be quantified by fluorescence spectrophotometry. The developed probe showed good detection sensitivity and selectivity and a good linear relationship between the fluorescence intensity and the concentration of 5 hmC within a 0-100nM range. Compared with other fluorescence detection methods, this method not only could determine trace amounts of 5 hmC from genomic DNA but also could eliminate the interference of fluorescent dyes and the need for purification. It also could avoid multiple labeling. Because the PBAQA-PGMA probe could enrich the content of glycosyl-5-hydroxymethyl-2-deoxycytidine from a complex ground substance, it will broaden the linear detection range and improve sensitivity. The limit of detection was calculated to be 0.167nM after enrichment. Furthermore, the method was successfully used to detect 5-hydroxymethylcytosine from mouse tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of plutonium in nitric acid solutions using energy dispersive L X-ray fluorescence with a low power X-ray generator

NASA Astrophysics Data System (ADS)

Py, J.; Groetz, J.-E.; Hubinois, J.-C.; Cardona, D.

2015-04-01

This work presents the development of an in-line energy dispersive L X-ray fluorescence spectrometer set-up, with a low power X-ray generator and a secondary target, for the determination of plutonium concentration in nitric acid solutions. The intensity of the L X-rays from the internal conversion and gamma rays emitted by the daughter nuclei from plutonium is minimized and corrected, in order to eliminate the interferences with the L X-ray fluorescence spectrum. The matrix effects are then corrected by the Compton peak method. A calibration plot for plutonium solutions within the range 0.1-20 g L-1 is given.

Identification of Dekkera bruxellensis (Brettanomyces) from Wine by Fluorescence In Situ Hybridization Using Peptide Nucleic Acid Probes

PubMed Central

Stender, Henrik; Kurtzman, Cletus; Hyldig-Nielsen, Jens J.; Sørensen, Ditte; Broomer, Adam; Oliveira, Kenneth; Perry-O'Keefe, Heather; Sage, Andrew; Young, Barbara; Coull, James

2001-01-01

A new fluorescence in situ hybridization method using peptide nucleic acid (PNA) probes for identification of Brettanomyces is described. The test is based on fluorescein-labeled PNA probes targeting a species-specific sequence of the rRNA of Dekkera bruxellensis. The PNA probes were applied to smears of colonies, and results were interpreted by fluorescence microscopy. The results obtained from testing 127 different yeast strains, including 78 Brettanomyces isolates from wine, show that the spoilage organism Brettanomyces belongs to the species D. bruxellensis and that the new method is able to identify Brettanomyces (D. bruxellensis) with 100% sensitivity and 100% specificity. PMID:11157265

Characterization of carbohydrates using highly fluorescent 2-aminobenzoic acid tag following gel electrophoresis of glycoproteins.

PubMed

Anumula, K R; Du, P

1999-11-15

Application of the most sensitive fluorescent label 2-aminobenzoic acid (anthranilic acid, AA) for characterization of carbohydrates from the glycoproteins ( approximately 15 pmol) separated by polyacrylamide gel electrophoresis is described. AA label is used for the determination of both monosaccharide composition and oligosaccharide map. For the monosaccharide determination, bands containing the glycoprotein of interest are excised from the polyvinylidene fluoride (PVDF) membrane blots, hydrolyzed in 20% trifluoroacetic acid, derivatized, and analyzed by C-18 reversed-phase high-performance liquid chromatography. For the oligosaccharide mapping, bands were digested with peptide N-glycosidase F (PNGase F) in order to release the N-linked oligosaccharides, derivatized, and analyzed by normal-phase anion-exchange chromatography. For convenience, the PNGase F digestion was performed in 1:100 diluted ammonium hydroxide overnight. The oligosaccharide yield from ammonium hydroxide-PNGase F digestion was better or equal to all the other reported procedures, and the presumed "oligosaccharide-amine" product formed in the reaction mixture did not interfere with labeling of the oligosaccharides under the conditions used for derivatization. Sequencing of oligosaccharides can be performed using the same mapping method following treatment with an array of glycosidases. In addition, the mapping method is useful for determining the relative and simultaneous distribution of sialic acid and fucose. Copyright 1999 Academic Press.

Chiral separation of amino acids in biological fluids by micellar electrokinetic chromatography with laser-induced fluorescence detection.

PubMed

Thorsén, G; Bergquist, J

2000-08-18

A method is presented for the chiral analysis of amino acids in biological fluids using micellar electrokinetic chromatography (MEKC) and laser-induced fluorescence (LIF). The amino acids are derivatized with the chiral reagent (+/-)-1-(9-anthryl)-2-propyl chloroformate (APOC) and separated using a mixed micellar separation system. No tedious pre-purification of samples is required. The excellent separation efficiency and good detection capabilities of the MEKC-LIF system are exemplified in the analysis of urine and cerebrospinal fluid. This is the first time MEKC has been reported for chiral analysis of amino acids in biological fluids. The amino acids D-alanine, D-glutamine, and D-aspartic acid have been observed in cerebrospinal fluid, and D-alanine and D-glutamic acid in urine. To the best of our knowledge no measurements of either D-alanine in cerebrospinal fluid or D-glutamic acid in urine have been presented in the literature before.

A cobalt oxyhydroxide-modified upconversion nanosystem for sensitive fluorescence sensing of ascorbic acid in human plasma

NASA Astrophysics Data System (ADS)

Cen, Yao; Tang, Jun; Kong, Xiang-Juan; Wu, Shuang; Yuan, Jing; Yu, Ru-Qin; Chu, Xia

2015-08-01

Ascorbic acid (AA), a potent antioxidant readily scavenging reactive species, is a crucial micronutrient involved in many biochemical processes. Here, we have developed a cobalt oxyhydroxide (CoOOH)-modified upconversion nanosystem for fluorescence sensing of AA activity in human plasma. The nanosystem consists of upconversion nanoparticles (UCNPs) NaYF4:30% Yb,0.5% Tm@NaYF4, which serve as energy donors, and CoOOH nanoflakes formed on the surface of UCNPs, which act as efficient energy acceptors. The fluorescence resonance energy transfer (FRET) process from the UCNPs to the absorbance of the CoOOH nanoflakes occurs in the nanosystem. The AA-mediated specific redox reaction reduces CoOOH into Co2+, leading to the inhibition of FRET, and resulting in the recovery of upconversion emission spectra. On the basis of these features, the nanosystem can be used for sensing AA activity with sensitivity and selectivity. Moreover, due to the minimizing background interference provided by UCNPs, the nanosystem has been applied to monitoring AA levels in human plasma sample with satisfactory results. The proposed approach may potentially provide an analytical platform for research and clinical diagnosis of AA related diseases.Ascorbic acid (AA), a potent antioxidant readily scavenging reactive species, is a crucial micronutrient involved in many biochemical processes. Here, we have developed a cobalt oxyhydroxide (CoOOH)-modified upconversion nanosystem for fluorescence sensing of AA activity in human plasma. The nanosystem consists of upconversion nanoparticles (UCNPs) NaYF4:30% Yb,0.5% Tm@NaYF4, which serve as energy donors, and CoOOH nanoflakes formed on the surface of UCNPs, which act as efficient energy acceptors. The fluorescence resonance energy transfer (FRET) process from the UCNPs to the absorbance of the CoOOH nanoflakes occurs in the nanosystem. The AA-mediated specific redox reaction reduces CoOOH into Co2+, leading to the inhibition of FRET, and resulting in the

Absorption, fluorescence, and acid-base equilibria of rhodamines in micellar media of sodium dodecyl sulfate

NASA Astrophysics Data System (ADS)

Obukhova, Elena N.; Mchedlov-Petrossyan, Nikolay O.; Vodolazkaya, Natalya A.; Patsenker, Leonid D.; Doroshenko, Andrey O.; Marynin, Andriy I.; Krasovitskii, Boris M.

2017-01-01

Rhodamine dyes are widely used as molecular probes in different fields of science. The aim of this paper was to ascertain to what extent the structural peculiarities of the compounds influence their absorption, emission, and acid-base properties under unified conditions. The acid-base dissociation (HR+ ⇄ R + H+) of a series of rhodamine dyes was studied in sodium n-dodecylsulfate micellar solutions. In this media, the form R exists as a zwitterion R±. The indices of apparent ionization constants of fifteen rhodamine cations HR+ with different substituents in the xanthene moiety vary within the range of pKaapp = 5.04 to 5.53. The distinct dependence of emission of rhodamines bound to micelles on pH of bulk water opens the possibility of using them as fluorescent interfacial acid-base indicators.

Intraoperative Detection of Superficial Liver Tumors by Fluorescence Imaging Using Indocyanine Green and 5-aminolevulinic Acid.

PubMed

Kaibori, Masaki; Matsui, Kosuke; Ishizaki, Morihiko; Iida, Hiroya; Okumura, Tadayoshi; Sakaguchi, Tatsuma; Inoue, Kentaro; Ikeura, Tsukasa; Asano, Hiroaki; Kon, Masanori

2016-04-01

Indocyanine green (ICG) and the porphyrin precursor 5-aminolevulinic acid (5-ALA) have been approved as fluorescence imaging agents in the clinical setting. This study evaluated the usefulness of fluorescence imaging with both ICG and 5-ALA for intraoperative identification of latent small liver tumors. There were 48 patients who had main tumors within 5 mm of the liver surface. 5-ALA hydrochloride was orally administered to patients 3 h before surgery. ICG had been intravenously injected within 14 days prior to surgery. Intraoperatively, after visual inspection, manual palpation and ultrasonography fluorescence images of the liver surface were obtained with ICG and 5-ALA prior to resection. With ICG, the sensitivity, specificity and accuracy for detecting the preoperatively identified main tumors were 96%, 50% and 94%, respectively. Twelve latent small tumors were newly detected on the liver surface using ICG, five of which proved to be carcinomas. With 5-ALA, the sensitivity, specificity and accuracy for detecting the main tumors were 57%, 100% and 58%, respectively. Five latent small tumors were newly detected using 5-ALA; all were carcinomas. Overall, five new tumors were detected by both ICG and 5-ALA fluorescence imaging; two were hepatocellular carcinomas (HCCs) and three were metastases of colorectal cancer. The sensitivity and specificity of ICG fluorescence imaging for main tumor detection were relatively high and low, respectively, but the opposite was true of 5-ALA imaging. Fluorescence imaging using 5-ALA may provide greater specificity in the detection of surface-invisible malignant liver tumors than using ICG fluorescence imaging alone. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

On-chip transduction of nucleic acid hybridization using spatial profiles of immobilized quantum dots and fluorescence resonance energy transfer.

PubMed

Tavares, Anthony J; Noor, M Omair; Vannoy, Charles H; Algar, W Russ; Krull, Ulrich J

2012-01-03

The glass surface of a glass-polydimethylsiloxane (PDMS) microfluidic channel was modified to develop a solid-phase assay for quantitative determination of nucleic acids. Electroosmotic flow (EOF) within channels was used to deliver and immobilize semiconductor quantum dots (QDs), and electrophoresis was used to decorate the QDs with oligonucleotide probe sequences. These processes took only minutes to complete. The QDs served as energy donors in fluorescence resonance energy transfer (FRET) for transduction of nucleic acid hybridization. Electrokinetic injection of fluorescent dye (Cy3) labeled oligonucleotide target into a microfluidic channel and subsequent hybridization (within minutes) provided the proximity for FRET, with emission from Cy3 being the analytical signal. The quantification of target concentration was achieved by measurement of the spatial length of coverage by target along a channel. Detection of femtomole quantities of target was possible with a dynamic range spanning an order of magnitude. The assay provided excellent resistance to nonspecific interactions of DNA. Further selectivity of the assay was achieved using 20% formamide, which allowed discrimination between a fully complementary target and a 3 base pair mismatch target at a contrast ratio of 4:1. © 2011 American Chemical Society

Fluorescence-guided surgery with 5-aminolevulinic acid for resection of brain tumors in children--a technical report.

PubMed

Beez, Thomas; Sarikaya-Seiwert, Sevgi; Steiger, Hans-Jakob; Hänggi, Daniel

2014-03-01

5-aminolevulinic acid (5-ALA) can be used as an adjunct for the surgery of adult malignant glioma and improves the rate of gross total resection and patient survival. So far, only three casuistic reports of fluorescence-guided surgery used in children have been published. We report our pilot series of 16 pediatric brain tumors treated with 5-ALA. Sixteen patients (mean age 9 years, range 1-16 years) received a standardized 5-ALA dose according to the published protocol after informed parental consent. The fluorescence status (positive versus negative) in correlation with histology as well as blood samples and adverse clinical symptoms were recorded. Histology revealed pilocytic astrocytoma (n = 7), classical medulloblastoma (n = 4), anaplastic astrocytoma (n = 1), glioblastoma (n = 3) and anaplastic ependymoma (n = 1). Positive fluorescence was observed in cases of anaplastic astrocytoma, glioblastoma, and medulloblastoma, respectively. Significant increases were registered for alanine aminotransferase (14.92 ± 1.106 U/l vs. 37.70 ± 3.795 U/l, P = 0.0020) and gamma glutamyl transpeptidase (12.69 ± 1.638 U/l vs. 39.29 ± 6.342 U/l, P = 0.0156), correlated with young age. No further adverse reactions were evident. Positive fluorescence was observed in two high-grade gliomas and one medulloblastoma after oral administration of 5-ALA. Thus, 5-ALA appears capable of inducing fluorescence in pediatric high-grade tumors. Adverse reactions observed in children were similar to those reported for adults, although very young children might be at increased risk. Further studies are required to elucidate pharmacokinetic and pharmacodynamic properties of 5-ALA in children and to assess its prognostic role in the resection of pediatric brain tumors.

Enhancing early bladder cancer detection with fluorescence-guided endoscopic optical coherence tomography

NASA Astrophysics Data System (ADS)

Pan, Y. T.; Xie, T. Q.; Du, C. W.; Bastacky, S.; Meyers, S.; Zeidel, M. L.

2003-12-01

We report an experimental study of the possibility of enhancing early bladder cancer diagnosis with fluorescence-image-guided endoscopic optical coherence tomography (OCT). After the intravesical instillation of a 10% solution of 5-aminolevulinic acid, simultaneous fluorescence imaging (excitation of 380-420 nm, emission of 620-700 nm) and OCT are performed on rat bladders to identify the photochemical and morphological changes associated with uroepithelial tumorigenesis. The preliminary results of our ex vivo study reveal that both fluorescence and OCT can identify early uroepithelial cancers, and OCT can detect precancerous lesions (e.g., hyperplasia) that fluorescence may miss. This suggests that a cystoscope combining 5-aminolevulinic acid fluorescence and OCT imaging has the potential to enhance the efficiency and sensitivity of early bladder cancer diagnosis.

Dual-modality, fluorescent, PLGA encapsulated bismuth nanoparticles for molecular and cellular fluorescence imaging and computed tomography

NASA Astrophysics Data System (ADS)

Swy, Eric R.; Schwartz-Duval, Aaron S.; Shuboni, Dorela D.; Latourette, Matthew T.; Mallet, Christiane L.; Parys, Maciej; Cormode, David P.; Shapiro, Erik M.

2014-10-01

Reports of molecular and cellular imaging using computed tomography (CT) are rapidly increasing. Many of these reports use gold nanoparticles. Bismuth has similar CT contrast properties to gold while being approximately 1000-fold less expensive. Herein we report the design, fabrication, characterization, and CT and fluorescence imaging properties of a novel, dual modality, fluorescent, polymer encapsulated bismuth nanoparticle construct for computed tomography and fluorescence imaging. We also report on cellular internalization and preliminary in vitro and in vivo toxicity effects of these constructs. 40 nm bismuth(0) nanocrystals were synthesized and encapsulated within 120 nm Poly(dl-lactic-co-glycolic acid) (PLGA) nanoparticles by oil-in-water emulsion methodologies. Coumarin-6 was co-encapsulated to impart fluorescence. High encapsulation efficiency was achieved ~70% bismuth w/w. Particles were shown to internalize within cells following incubation in culture. Bismuth nanocrystals and PLGA encapsulated bismuth nanoparticles exhibited >90% and >70% degradation, respectively, within 24 hours in acidic, lysosomal environment mimicking media and both remained nearly 100% stable in cytosolic/extracellular fluid mimicking media. μCT and clinical CT imaging was performed at multiple X-ray tube voltages to measure concentration dependent attenuation rates as well as to establish the ability to detect the nanoparticles in an ex vivo biological sample. Dual fluorescence and CT imaging is demonstrated as well. In vivo toxicity studies in rats revealed neither clinically apparent side effects nor major alterations in serum chemistry and hematology parameters. Calculations on minimal detection requirements for in vivo targeted imaging using these nanoparticles are presented. Indeed, our results indicate that these nanoparticles may serve as a platform for sensitive and specific targeted molecular CT and fluorescence imaging.Reports of molecular and cellular imaging using

Chiral capillary electrophoresis with UV-excited fluorescence detection for the enantioselective analysis of 9-fluorenylmethoxycarbonyl-derivatized amino acids.

PubMed

Prior, Amir; Coliva, Giulia; de Jong, Gerhardus J; Somsen, Govert W

2018-05-29

The potential of capillary electrophoresis (CE) with ultraviolet (UV)-excited fluorescence detection for sensitive chiral analysis of amino acids (AAs) was investigated. DL-AAs were derivatized with 9-fluorenylmethoxycarbonyl chloride (FMOC)-Cl to allow their fluorescence detection and enhance enantioseparation. Fluorescence detection was achieved employing optical fibers, leading UV excitation light (< 300 nm) from a Xe-Hg lamp to the capillary window, and fluorescence emission to a spectrograph equipped with a charge-coupled device (CCD). Signal averaging over time and emission wavelength intervals was carried out to improve the signal-to-noise ratio of the FMOC-AAs. A background electrolyte (BGE) of 40 mM sodium tetraborate (pH 9.5), containing 15% isopropanol (v/v), 30 mM sodium dodecyl sulfate (SDS), and 30 mM β-cyclodextrin (β-CD), was found optimal for AA chemo- and enantioseparation. Enantioresolutions of 1.0 or higher were achieved for 16 proteinogenic DL-AAs. Limits of detection (LODs) were in the 10-100-nM range (injected concentration) for the D-AA enantiomers, except for FMOC-D-tryptophan (536 nM) which showed intramolecular fluorescence quenching. Linearity (R 2  > 0.997) and repeatability for peak height (relative standard deviations (RSDs) < 7.0%; n = 5) and electrophoretic mobility (RSDs < 0.6%; n = 5) of individual AA enantiomers were established for chiral analysis of DL-AA mixtures. The applicability of the method was investigated by the analysis of cerebrospinal fluid (CSF). Next to L-AAs, endogenous levels of D-glutamine and D-aspartic acid could be measured in CSF revealing enantiomeric ratios of 0.35 and 19.6%, respectively. This indicates the method's potential for the analysis of low concentrations of D-AAs in presence of abundant L-AAs.

Monitoring the Wet-Heat Inactivation Dynamics of Single Spores of Bacillus Species by Using Raman Tweezers, Differential Interference Contrast Microscopy, and Nucleic Acid Dye Fluorescence Microscopy▿

PubMed Central

Zhang, Pengfei; Kong, Lingbo; Wang, Guiwen; Setlow, Peter; Li, Yong-qing

2011-01-01

Dynamic processes during wet-heat treatment of individual spores of Bacillus cereus, Bacillus megaterium, and Bacillus subtilis at 80 to 90°C were investigated using dual-trap Raman spectroscopy, differential interference contrast (DIC) microscopy, and nucleic acid stain (SYTO 16) fluorescence microscopy. During spore wet-heat treatment, while the spores' 1:1 chelate of Ca2+ with dipicolinic acid (CaDPA) was released rapidly at a highly variable time Tlag, the levels of spore nucleic acids remained nearly unchanged, and the Tlag times for individual spores from the same preparation were increased somewhat as spore levels of CaDPA increased. The brightness of the spores' DIC image decreased by ∼50% in parallel with CaDPA release, and there was no spore cortex hydrolysis observed. The lateral diameters of the spores' DIC image and SYTO 16 fluorescence image also decreased in parallel with CaDPA release. The SYTO 16 fluorescence intensity began to increase during wet-heat treatment at a time before Tlag and reached maximum at a time slightly later than Trelease. However, the fluorescence intensities of wet-heat-inactivated spores were ∼15-fold lower than those of nutrient-germinated spores, and this low SYTO 16 fluorescence intensity may be due in part to the low permeability of the dormant spores' inner membranes to SYTO 16 and in part to nucleic acid denaturation during the wet-heat treatment. PMID:21602365

Prognostic value of residual fluorescent tissue in glioblastoma patients after gross total resection in 5-aminolevulinic Acid-guided surgery.

PubMed

Aldave, Guillermo; Tejada, Sonia; Pay, Eva; Marigil, Miguel; Bejarano, Bartolomé; Idoate, Miguel A; Díez-Valle, Ricardo

2013-06-01

There is evidence in the literature supporting that fluorescent tissue signal in fluorescence-guided surgery extends farther than tissue highlighted in gadolinium in T1 sequence magnetic resonance imaging (MRI), which is the standard to quantify the extent of resection. To study whether the presence of residual fluorescent tissue after surgery carries a different prognosis for glioblastoma (GBM) cases with complete resection confirmed by MRI. A retrospective review in our center found 118 consecutive patients with high-grade gliomas operated on with the use of fluorescence-guided surgery with 5-aminolevulinic acid. Within that series, the 52 patients with newly diagnosed GBM and complete resection of enhancing tumor (CRET) in early MRI were selected for analysis. We studied the influence of residual fluorescence in the surgical field on overall survival and neurological complication rate. Multivariate analysis included potential relevant factors: age, Karnofsky Performance Scale, O-methylguanine methyltransferase methylation promoter status, tumor eloquent location, preoperative tumor volume, and adjuvant therapy. The median overall survival was 27.0 months (confidence interval = 22.4-31.6) in patients with nonresidual fluorescence (n = 25) and 17.5 months (confidence interval = 12.5-22.5) for the group with residual fluorescence (n = 27) (P = .015). The influence of residual fluorescence was maintained in the multivariate analysis with all covariables, hazard ratio = 2.5 (P = .041). The neurological complication rate was 18.5% in patients with nonresidual fluorescence and 8% for the group with residual fluorescence (P = .267). GBM patients with CRET in early MRI and no fluorescent residual tissue had longer overall survival than patients with CRET and residual fluorescent tissue.

A novel single fluorophore-labeled double-stranded oligonucleotide probe for fluorescence-enhanced nucleic acid detection based on the inherent quenching ability of deoxyguanosine bases and competitive strand-displacement reaction.

PubMed

Zhang, Yingwei; Tian, Jingqi; Li, Hailong; Wang, Lei; Sun, Xuping

2012-01-01

We develop a novel single fluorophore-labeled double-stranded oligonucleotide (OND) probe for rapid, nanostructure-free, fluorescence-enhanced nucleic acid detection for the first time. We further demonstrate such probe is able to well discriminate single-base mutation in nucleic acid. The design takes advantage of an inherent quenching ability of guanine bases. The short strand of the probe is designed with an end-labeled fluorophore that is placed adjacent to two guanines as the quencher located on the long opposite strand, resulting in great quenching of dye fluorescence. In the presence of a target complementary to the long strand of the probe, a competitive strand-displacement reaction occurs and the long strand forms a more stable duplex with the target, resulting in the two strands of the probe being separated from each other. As a consequence of this displacement, the fluorophore and the quencher are no longer in close proximity and dye fluorescence increases, signaling the presence of target.

Glucose sensing molecules having selected fluorescent properties

DOEpatents

Satcher, Jr., Joe H.; Lane, Stephen M.; Darrow, Christopher B.; Cary, Douglas R.; Tran, Joe Anh

2004-01-27

An analyte sensing fluorescent molecule that employs intramolecular electron transfer is designed to exhibit selected fluorescent properties in the presence of analytes such as saccharides. The selected fluorescent properties include excitation wavelength, emission wavelength, fluorescence lifetime, quantum yield, photostability, solubility, and temperature or pH sensitivity. The compound comprises an aryl or a substituted phenyl boronic acid that acts as a substrate recognition component, a fluorescence switch component, and a fluorophore. The fluorophore and switch component are selected such that the value of the free energy for electron transfer is less than about 3.0 kcal mol.sup.-1. Fluorescent compounds are described that are excited at wavelengths greater than 400 nm and emit at wavelengths greater than 450 nm, which is advantageous for optical transmission through skin. The fluorophore is typically selected from transition metal-ligand complexes and thiazine, oxazine, oxazone, or oxazine-one as well as anthracene compounds. The fluorescent compound can be immobilized in a glucose permeable biocompatible polymer matrix that is implantable below the skin.

[Development of fluorescent probes for bone imaging in vivo ~Fluorescent probes for intravital imaging of osteoclast activity~.

PubMed

Minoshima, Masafumi; Kikuchi, Kazuya

Fluorescent molecules are widely used as a tool to directly visualize target biomolecules in vivo. Fluorescent probes have the advantage that desired function can be rendered based on rational design. For bone-imaging fluorescent probes in vivo, they should be delivered to bone tissue upon administration. Recently, a fluorescent probe for detecting osteoclast activity was developed. The fluorescent probe has acid-sensitive fluorescence property, specific delivery to bone tissue, and durability against laser irradiation, which enabled real-time intravital imaging of bone-resorbing osteoclasts for a long period of time.

Comparison of the haematoxylin basic fuchsin picric acid method and the fluorescence of haematoxylin and eosin stained sections for the identification of early myocardial infarction.

PubMed Central

Al-Rufaie, H K; Florio, R A; Olsen, E G

1983-01-01

A retrospective study has been carried out on the necropsy material from 30 patients who have died after a clinically diagnosed myocardial infarction. This study has been undertaken to compare the reliability of the fluorescence of infarcted myocardium when stained by haematoxylin and eosin and an adjacent section stained by the haematoxylin basic fuchsin picric acid (HBFP) method to detect early ischaemia. The results showed that the fluorescence technique is reliable, reproducible and coincides with the findings obtained by HBFP stain. Images PMID:6189866

Comparison of three-dimensional fluorescence analysis methods for predicting formation of trihalomethanes and haloacetic acids.

PubMed

Peleato, Nicolás M; Andrews, Robert C

2015-01-01

This work investigated the application of several fluorescence excitation-emission matrix analysis methods as natural organic matter (NOM) indicators for use in predicting the formation of trihalomethanes (THMs) and haloacetic acids (HAAs). Waters from four different sources (two rivers and two lakes) were subjected to jar testing followed by 24hr disinfection by-product formation tests using chlorine. NOM was quantified using three common measures: dissolved organic carbon, ultraviolet absorbance at 254 nm, and specific ultraviolet absorbance as well as by principal component analysis, peak picking, and parallel factor analysis of fluorescence spectra. Based on multi-linear modeling of THMs and HAAs, principle component (PC) scores resulted in the lowest mean squared prediction error of cross-folded test sets (THMs: 43.7 (μg/L)(2), HAAs: 233.3 (μg/L)(2)). Inclusion of principle components representative of protein-like material significantly decreased prediction error for both THMs and HAAs. Parallel factor analysis did not identify a protein-like component and resulted in prediction errors similar to traditional NOM surrogates as well as fluorescence peak picking. These results support the value of fluorescence excitation-emission matrix-principal component analysis as a suitable NOM indicator in predicting the formation of THMs and HAAs for the water sources studied. Copyright © 2014. Published by Elsevier B.V.

Fluorescence cytology with 5-aminolevulinic acid in EUS-guided FNA as a method for differentiating between malignant and benign lesions (with video).

PubMed

Ikeura, Tsukasa; Takaoka, Makoto; Uchida, Kazushige; Shimatani, Masaaki; Miyoshi, Hideaki; Kato, Kota; Ohe, Chisato; Uemura, Yoshiko; Kaibori, Masaki; Kwon, A-Hon; Okazaki, Kazuichi

2015-01-01

EUS-guided FNA (EUS-FNA) has been increasingly performed to obtain specimens for the pathological evaluation of patients with GI and pancreaticobiliary masses as well as lymphadenopathies of unknown origin. Photodynamic diagnosis by using 5-aminolebulinic acid (ALA) has been reported to be useful for enabling the visual differentiation between malignant and normal tissue in various cancers. To evaluate the diagnostic accuracy of fluorescence cytology with ALA in EUS-FNA. A prospective study. A single center. A total of 28 consecutive patients who underwent EUS-FNA for the pathological diagnosis of a pancreaticobiliary mass lesion or intra-abdominal lymphadenopathy of unknown origin. Patients were orally administered ALA 3 to 6 hours before EUS-FNA. The sample was obtained via EUS-FNA for fluorescence cytology and conventional cytology. A single gastroenterologist performed the fluorescence cytology by using fluorescence microscopy after the procedure, independently of the conventional cytology by pathologists. The accuracy of fluorescence cytology with ALA in the differentiation between benign and malignant lesions by comparing the results of fluorescence cytology with the final diagnosis. Of the 28 patients included in the study, 22 were considered as having malignant lesions and 6 patients as having benign lesions. Fluorescence cytology could correctly discriminate between benign and malignant lesions in all patients. Therefore, both the sensitivity and specificity of fluorescence cytology were 100% in our study. Fluorescence cytology was performed by only 1 gastroenterologist with a small number of patients. Fluorescence cytology with ALA in EUS-FNA may be an effective and simple method for differentiating between benign and malignant lesions. Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

High resolution and high sensitivity methods for oligosaccharide mapping and characterization by normal phase high performance liquid chromatography following derivatization with highly fluorescent anthranilic acid.

PubMed

Anumula, K R; Dhume, S T

1998-07-01

Facile labeling of oligosaccharides (acidic and neutral) in a nonselective manner was achieved with highly fluorescent anthranilic acid (AA, 2-aminobenzoic acid) (more than twice the intensity of 2-aminobenzamide, AB) for specific detection at very high sensitivity. Quantitative labeling in acetate-borate buffered methanol (approximately pH 5.0) at 80 degreesC for 60 min resulted in negligible or no desialylation of the oligosaccharides. A high resolution high performance liquid chromatographic method was developed for quantitative oligosaccharide mapping on a polymeric-NH2bonded (Astec) column operating under normal phase and anion exchange (NP-HPAEC) conditions. For isolation of oligosaccharides from the map by simple evaporation, the chromatographic conditions developed use volatile acetic acid-triethylamine buffer (approximately pH 4.0) systems. The mapping and characterization technology was developed using well characterized standard glycoproteins. The fluorescent oligosaccharide maps were similar to the maps obtained by the high pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD), except that the fluorescent maps contained more defined peaks. In the map, the oligosaccharides separated into groups based on charge, size, linkage, and overall structure in a manner similar to HPAEC-PAD with contribution of -COOH function from the label, anthranilic acid. However, selectivity of the column for sialic acid linkages was different. A second dimension normal phase HPLC (NP-HPLC) method was developed on an amide column (TSK Gel amide-80) for separation of the AA labeled neutral complex type and isomeric structures of high mannose type oligosaccharides. The oligosaccharides labeled with AA are compatible with biochemical and biophysical techniques, and use of matrix assisted laser desorption mass spectrometry for rapid determination of oligosaccharide mass map of glycoproteins is demonstrated. High resolution of NP-HPAEC and NP-HPLC methods

Fluorescent probes and bioimaging: alkali metals, alkaline earth metals and pH.

PubMed

Yin, Jun; Hu, Ying; Yoon, Juyoung

2015-07-21

All living species and life forms have an absolute requirement for bio-functional metals and acid-base equilibrium chemistry owing to the critical roles they play in biological processes. Hence, a great need exists for efficient methods to detect and monitor biometals and acids. In the last few years, great attention has been paid to the development of organic molecule based fluorescent chemosensors. The availability of new synthetic fluorescent probes has made fluorescence microscopy an indispensable tool for tracing biologically important molecules and in the area of clinical diagnostics. This review highlights the recent advances that have been made in the design and bioimaging applications of fluorescent probes for alkali metals and alkaline earth metal cations, including lithium, sodium and potassium, magnesium and calcium, and for pH determination within biological systems.

High-throughput imaging of adult fluorescent zebrafish with an LED fluorescence macroscope

PubMed Central

Blackburn, Jessica S; Liu, Sali; Raimondi, Aubrey R; Ignatius, Myron S; Salthouse, Christopher D; Langenau, David M

2011-01-01

Zebrafish are a useful vertebrate model for the study of development, behavior, disease and cancer. A major advantage of zebrafish is that large numbers of animals can be economically used for experimentation; however, high-throughput methods for imaging live adult zebrafish had not been developed. Here, we describe protocols for building a light-emitting diode (LED) fluorescence macroscope and for using it to simultaneously image up to 30 adult animals that transgenically express a fluorescent protein, are transplanted with fluorescently labeled tumor cells or are tagged with fluorescent elastomers. These protocols show that the LED fluorescence macroscope is capable of distinguishing five fluorescent proteins and can image unanesthetized swimming adult zebrafish in multiple fluorescent channels simultaneously. The macroscope can be built and used for imaging within 1 day, whereas creating fluorescently labeled adult zebrafish requires 1 hour to several months, depending on the method chosen. The LED fluorescence macroscope provides a low-cost, high-throughput method to rapidly screen adult fluorescent zebrafish and it will be useful for imaging transgenic animals, screening for tumor engraftment, and tagging individual fish for long-term analysis. PMID:21293462

Separation and detection of VX and its methylphosphonic acid degradation products on a microchip using indirect laser-induced fluorescence.

PubMed

Heleg-Shabtai, Vered; Gratziany, Natzach; Liron, Zvi

2006-05-01

The application of indirect LIF (IDLIF) technique for on-chip electrophoretic separation and detection of the nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothiolate (VX) and its major phosphonic degradation products, ethyl methylphosphonic acid (EMPA) and methylphosphonic acid (MPA) was demonstrated. Separation and detection of MPA degradation products of VX and the nerve agent isopropyl methylphosphonofluoridate (GB) are presented. The negatively charged dye eosin was found to be a good fluorescent marker for both the negatively charged phosphonic acids and the positively charged VX, and was chosen as the IDLIF visualization fluorescent dye. Separation and detection of VX, EMPA, and MPA in a simple-cross microchip were completed within less than a minute, and consumed only a 50 pL sample volume. A characteristic system peak that appeared in all IDLIF electropherograms served as an internal standard that increased the reliability of peak identification. The negative peak of both VX and the MPAs is in agreement with indirect detection theory and with previous reports in the literature. The LOD of VX and EMPA by IDLIF was 30 and 37 microM, respectively. Despite the fact that the detection sensitivity is relatively low, the rapid simultaneous on-chip analysis of both VX and its degradation products as well as the separation and detection of the MPA degradation products of both VX and GB, increases detection reliability and may present a choice when sensitivity is not critical compared with speed and simplicity of the assay.

New method of acne disease fluorescent diagnostics in natural and fluorescent light and treatment control

NASA Astrophysics Data System (ADS)

Karimova, L. N.; Berezin, A. N.; Shevchik, S. A.; Kharnas, S. S.; Kusmin, S. G.; Loschenov, V. B.

2005-08-01

In the given research the new method of fluorescent diagnostics (FD) and photodynamic therapy (PDT) control of acne disease is submitted. Method is based on simultaneous diagnostics in natural and fluorescent light. PDT was based on using 5-ALA (5- aminolevulinic acid) preparation and 600-730 nanometers radiation. If the examined site of a skin possessed a high endogenous porphyrin fluorescence level, PDT was carried out without 5-ALA. For FD and treatment control a dot spectroscopy and the fluorescent imaging of the affected skin were used.

Synthesis and characterization of bioactive conjugated near-infrared fluorescent proteinoid-poly(L-lactic acid) hollow nanoparticles for optical detection of colon cancer

PubMed Central

Kolitz-Domb, Michal; Corem-Salkmon, Enav; Grinberg, Igor; Margel, Shlomo

2014-01-01

Colon cancer is one of the major causes of death in the Western world. Early detection significantly improves long-term survival for patients with colon cancer. Near-infrared (NIR) fluorescent nanoparticles are promising candidates for use as contrast agents for tumor detection. Using NIR offers several advantages for bioimaging compared with fluorescence in the visible spectrum: lower autofluorescence of biological tissues and lower absorbance and, consequently, deeper penetration into biomatrices. The present study describes the preparation of new NIR fluorescent proteinoid-poly(L-lactic acid) (PLLA) nanoparticles. For this purpose, a P(EF-PLLA) random copolymer was prepared by thermal copolymerization of L-glutamic acid (E) with L-phenylalanine (F) and PLLA. Under suitable conditions, this proteinoid-PLLA copolymer can self-assemble to nanosized hollow particles of relatively narrow size distribution. This self-assembly process was used for encapsulation of the NIR dye indocyanine green. The encapsulation process increases significantly the photostability of the dye. These NIR fluorescent nanoparticles were found to be stable and nontoxic. Leakage of the NIR dye from these nanoparticles into phosphate-buffered saline containing 4% human serum albumin was not detected. Tumor-targeting ligands such as peanut agglutinin and anticarcinoembryonic antigen antibodies were covalently conjugated to the surface of the NIR fluorescent P(EF-PLLA) nanoparticles, thereby increasing the fluorescent signal of tumors with upregulated corresponding receptors. Specific colon tumor detection by the NIR fluorescent P(EF-PLLA) nanoparticles was demonstrated in a chicken embryo model. In future work, we plan to extend this study to a mouse model, as well as to encapsulate a cancer drug such as doxorubicin within these nanoparticles for therapeutic applications. PMID:25382975

A long-wavelength fluorescent squarylium cyanine dye possessing boronic acid for sensing monosaccharides and glycoproteins with high enhancement in aqueous solution.

PubMed

Saito, Shingo; Massie, Tara L; Maeda, Takeshi; Nakazumi, Hiroyuki; Colyer, Christa L

2012-01-01

Fluorescence sensing of saccharides and glycoproteins using a boronic acid functionalized squarylium cyanine dye ("SQ-BA") is characterized in terms of synthetic, fluorometric, thermodynamic and kinetic parameters. In our previous work, this newly synthesized dye was successfully applied to the separation and quantification of Gram-positive bacteria by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF); however, the fundamental properties of the dye and its saccharide complexes still required elucidation, as presented in this paper. The dye itself forms nonemissive, soluble aggregates in aqueous solution. With the addition of a monosaccharide, the dye aggregate dissociates to form an emissive monomer accompanied by the formation of a cyclic cis-diol ester with long-wavelength emission (λ(ex) = 630 nm, λ(em) = 660 nm). A very large fluorescence enhancement factor of 18× was observed for the sensing dye as a fructose complex at pH 10, yielding a limit of detection of 10 μM fructose. The relative order of fluorescence enhancement of SQ-BA with other monosaccharides was found to be: fructose > ribose > arabinose ≈ galactose > xylose > mannose > rhamnose > fucose ≈ glucose; and apparent affinity constants of 10(2.80), 10(2.08) and 10(0.86) M(-1) were determined for fructose, ribose and glucose, respectively. Formation of the emissive complexes occurred within minutes, proving the kinetics of the sugar-dye interactions to be suitable for on-column labeling methods in CE-LIF. Furthermore, the sensing dye was successfully applied to glycoproteins, mucin type I-S and type III, which were detected with high sensitivity in batch aqueous solution as a result of the sugar-selective boronic acid-diol esterification as well as hydrophobic interactions.

A Long-Wavelength Fluorescent Squarylium Cyanine Dye Possessing Boronic Acid for Sensing Monosaccharides and Glycoproteins with High Enhancement in Aqueous Solution

PubMed Central

Saito, Shingo; Massie, Tara L.; Maeda, Takeshi; Nakazumi, Hiroyuki; Colyer, Christa L.

2012-01-01

Fluorescence sensing of saccharides and glycoproteins using a boronic acid functionalized squarylium cyanine dye (“SQ-BA”) is characterized in terms of synthetic, fluorometric, thermodynamic and kinetic parameters. In our previous work, this newly synthesized dye was successfully applied to the separation and quantification of Gram-positive bacteria by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF); however, the fundamental properties of the dye and its saccharide complexes still required elucidation, as presented in this paper. The dye itself forms nonemissive, soluble aggregates in aqueous solution. With the addition of a monosaccharide, the dye aggregate dissociates to form an emissive monomer accompanied by the formation of a cyclic cis-diol ester with long-wavelength emission (λex = 630 nm, λem = 660 nm). A very large fluorescence enhancement factor of 18× was observed for the sensing dye as a fructose complex at pH 10, yielding a limit of detection of 10 μM fructose. The relative order of fluorescence enhancement of SQ-BA with other monosaccharides was found to be: fructose > ribose > arabinose ≈ galactose > xylose > mannose > rhamnose > fucose ≈ glucose; and apparent affinity constants of 102.80, 102.08 and 100.86 M−1 were determined for fructose, ribose and glucose, respectively. Formation of the emissive complexes occurred within minutes, proving the kinetics of the sugar-dye interactions to be suitable for on-column labeling methods in CE-LIF. Furthermore, the sensing dye was successfully applied to glycoproteins, mucin type I–S and type III, which were detected with high sensitivity in batch aqueous solution as a result of the sugar-selective boronic acid-diol esterification as well as hydrophobic interactions. PMID:22778592

Fluorescent nanodiamonds as highly stable biomarker for endotoxin verification

NASA Astrophysics Data System (ADS)

Bergmann, Thorsten; Burg, Jan Michael; Lilholt, Maria; Maeder, Ulf; Beer, Sebastian; Salzig, Denise; Ebrahimi, Mehrdad; Czermak, Peter; Fiebich, Martin

2012-03-01

Fluorescent nanodiamonds (ND) provide advantageous properties as a fluorescent biomarker for in vitro and in vivo studies. The maximum fluorescence occurs around 700 nm, they do not show photobleaching or blinking and seem to be nontoxic. After a pretreatment with strong acid fluorescent ND can be functionalized and coupled to endotoxin. Endotoxin is a decay product of bacteria and causes strong immune reactions. Therefore endotoxin has to be removed for most applications. An effective removal procedure is membrane filtration. The endotoxin, coupled to fluorescent ND can be visualized by using confocal microscopy which allows the investigation of the separation mechanisms of the filtration process within the membranes.

Modulation of p-Cyanophenylalanine Fluorescence by Amino Acid Side-chains and Rational Design of Fluorescence Probes of α-Helix Formation

PubMed Central

Taskent-Sezgin, Humeyra; Marek, Peter; Thomas, Rosanne; Goldberg, Daniel; Chung, Juah; Carrico, Isaac; Raleigh, Daniel P.

2011-01-01

p-Cyanophenylalanine is an extremely useful fluorescence probe of protein structure which can be recombinantly and chemically incorporated into proteins. The probe has been used to study protein folding, protein-membrane interactions, protein-peptide interactions and amyloid formation, however the factors that control its fluorescence are not fully understood. Hydrogen bonding to the cyano group is known to play a major role in modulating the fluorescence quantum yield, but the role of potential side-chain quenchers has not yet been elucidated. A systematic study on the effects of different side-chains on p-cyanophenylalanine fluorescence is reported. Tyr is found to have the largest effect followed by deprotonated His, Met, Cys, protonated His, Asn, Arg, and protonated Lys. Deprotonated amino groups are much more effective fluorescence quenchers than protonated amino groups. Free neutral imidazole and hydroxide ion are also effective quenchers of p-cyanophenylalanine fluorescence with Stern-Volmer constants of 39.8 M−1 and 22.1 M−1, respectively. The quenching of p-cyanophenylalanine fluorescence by specific side-chains is exploited to develop specific, high sensitivity, fluorescence probes of helix formation. The approach is demonstrated with Ala based peptides that contain a p-cyanophenylalanine-His or a p-cyanophenylalanine-Tyr pair located at positions i and i+4. The p-cyanophenylalanine-His pair is most useful when the His side-chain is deprotonated and is, thus, complimentary to Trp-His pair which is most sensitive when the His side-chain is protonated. PMID:20565125

Use of a Novel Rover-mounted Fluorescence Imager and Fluorescent Probes to Detect Biological Material in the Atacama Desert in Daylight

NASA Technical Reports Server (NTRS)

Weinstein, S.; Pane, D.; Warren-Rhodes, K.; Cockell, C.; Ernst, L. A.; Minkley, E.; Fisher, G.; Emani, S.; Wettergreen, D. S.; Wagner, M.

2005-01-01

We have developed an imaging system, the Fluorescence Imager (FI), for detecting fluorescence signals from sparse microorganisms and biofilms during autonomous rover exploration. The fluorescence signals arise both from naturally occurring chromophores, such as chlorophyll of cyanobacteria and lichens, and from fluorescent probes applied to soil and rocks. Daylight imaging has been accomplished by a novel use of a high-powered flashlamp synchronized to a CCD camera. The fluorescent probes are cell permanent stains that have extremely low intrinsic fluorescence (quantum yields less than 0.01) and a large fluorescence enhancement (quantum yields greater than 0.4) when bound to the target. Each probe specifically targets either carbohydrates, proteins, nucleic acids or membrane lipids, the four classes of macromolecules found in terrestrial life. The intent of the probes is to interrogate the environment for surface and endolithic life forms.

Poly-adenine-mediated fluorescent spherical nucleic acid probes for live-cell imaging of endogenous tumor-related mRNA.

PubMed

Zhu, Dan; Zhao, Dongxia; Huang, Jiaxuan; Zhu, Yu; Chao, Jie; Su, Shao; Li, Jiang; Wang, Lihua; Shi, Jiye; Zuo, Xiaolei; Weng, Lixing; Li, Qian; Wang, Lianhui

2018-05-16

Identification of tumor-related mRNA in living cells hold great promise for early cancer diagnosis and pathological research. Herein, we present poly-adenine (polyA)-mediated fluorescent spherical nucleic acid (FSNA) probes for intracellular mRNA detection with regulable sensitivities by programmably adjusting the loading density of DNA on gold nano-interface. Gold nanoparticles (AuNPs) functionalized with polyA-tailed recognition sequences were hybridized to fluorescent "reporter" strands to fabricate fluorescence-quenched FSNA probes. While exposed to target gene, the "reporter" strands were released from FSNA through strand displacement and fluorescence was recovered. With polyA20 tail as the attaching block, the detection limit of FSNA probes was calculated to be 0.31 nM, which is ~55 fold lower than that of thiolated probes without surface density regulation. Quantitative intracellular mRNA detection and imaging could be achieved with polyA-mediated FSNA probes within 2 hours, indicating their application potential in rapid and sensitive intracellular target imaging. Copyright © 2018. Published by Elsevier Inc.

A potential approach for monitoring drinking water quality from groundwater systems using organic matter fluorescence as an early warning for contamination events.

PubMed

Stedmon, Colin A; Seredyńska-Sobecka, Bożena; Boe-Hansen, Rasmus; Le Tallec, Nicolas; Waul, Christopher K; Arvin, Erik

2011-11-15

The fluorescence characteristics of natural organic matter in a groundwater based drinking water supply plant were studied with the aim of applying it as a technique to identify contamination of the water supply. Excitation-emission matrices were measured and modeled using parallel factor analysis (PARAFAC) and used to identify which wavelengths provide the optimal signal for monitoring contamination events. The fluorescence was characterized by four components: three humic-like and one amino acid-like. The results revealed that the relative amounts of two of the humic-like components were very stable within the supply plant and distribution net and changed in a predictable fashion depending on which wells were supplying the water. A third humic-like component and an amino acid-like component did not differ between wells. Laboratory contamination experiments with wastewater revealed that combined they could be used as an indicator of microbial contamination. Their fluorescence spectra did not overlap with the other components and therefore the raw broadband fluorescence at the wavelengths specific to their fluorescence could be used to detect contamination. Contamination could be detected at levels equivalent to the addition of 60 μg C/L in drinking water with a TOC concentration of 3.3 mg C/L. The results of this study suggest that these types of drinking water systems, which are vulnerable to microbial contamination due to the lack of disinfectant treatment, can be easily monitored using online organic matter fluorescence as an early warning system to prompt further intensive sampling and appropriate corrective measures. Copyright © 2011 Elsevier Ltd. All rights reserved.

Quenching of p-Cyanophenylalanine Fluorescence by Various Anions.

PubMed

Pazos, Ileana M; Roesch, Rachel M; Gai, Feng

2013-03-20

To expand the spectroscopic utility of the non-natural amino acid p -cyanophenylalanine (Phe CN ), we examine the quenching efficiencies of a series of commonly encountered anions toward its fluorescence. We find that iodide exhibits an unusually large Stern-Volmer quenching constant, making it a convenient choice in Phe CN fluorescence quenching studies. Indeed, using the villin headpiece subdomain as a testbed we demonstrate that iodide quenching of Phe CN fluorescence offers a convenient means to reveal protein conformational heterogeneity. Furthermore, we show that the amino group of Phe CN strongly quenches its fluorescence, suggesting that Phe CN could be used as a local pH sensor.

Room temperature synthesis of pH-switchable polyaniline quantum dots as a turn-on fluorescent probe for acidic biotarget labeling.

PubMed

Liu, Yanfeng; Ding, Yin; Gou, Huilin; Huang, Xin; Zhang, Guiyang; Zhang, Qi; Liu, Yunzhong; Meng, Zhen; Xi, Kai; Jia, Xudong

2018-04-05

The synthesis of well-defined light-element-derived quantum dots (LEQDs) with advanced optical properties under mild conditions is highly desirable yet challenging. Here, a polyaniline (PANI) structure is introduced into carbon-rich LEQDs to yield well-defined, fluorescent polyaniline quantum dots (PAQDs), PAQD24, through a one-pot room temperature reaction. The mild synthetic conditions effectively minimize the defects introduced during the conventional synthesis and endow PAQD24 with desirable optical properties, including a narrow emission band (full width at half maximum = 55 nm), an optimal quantum yield of 32.5% and two-photon fluorescence. Furthermore, the bandgap of PAQD24 is highly sensitive toward pH variations in the near-neutral region, due to the proton doping and dedoping of the PANI structure. Such unique properties together with its fine bio-compatibility enable the application of this material as a turn-on fluorescent probe for the labeling of acidic biotargets from sub-cellular to organ levels, providing potential applications in diagnosis and surgery guidance for certain diseases.

A potential fluorescent probe: Maillard reaction product from glutathione and ascorbic acid for rapid and label-free dual detection of Hg(2+) and biothiols.

PubMed

Dong, Jiang Xue; Song, Xiao Fang; Shi, Yan; Gao, Zhong Feng; Li, Bang Lin; Li, Nian Bing; Luo, Hong Qun

2016-07-15

Maillard reactions and their fluorescent products have drawn much attention in the fields of food and life science, however, the application of fluorescent products separated from the reaction as an indicator for detection of certain substances in sensor field has not been mentioned. In this article, we report on an easy-to-synthesize and water-soluble fluorescent probe separated from the typical Maillard reaction products of glutathione and ascorbic acid, with excellent stability and high quantum yield (18.2%). The further application of the probe has been explored for dual detection of Hg(2+) and biothiols including cysteine, homocysteine, and glutathione, which is based on Hg(2+)-induced fluorescence quenching of the Maillard reaction fluorescent products (MRFPs) and the fluorescence recovery as the introduction of biothiols. This sensing system exhibits a good selectivity and sensitivity, and the linear ranges for Hg(2+), cysteine, homocysteine, and glutathione are 0.05-12, 0.5-10, 0.3-20, and 0.3-20μM, respectively. The detection limits for Hg(2+), cysteine, homocysteine, and glutathione are 22, 47, 96, and 30nM at a signal-to-noise ratio of 3, respectively. Furthermore, the practical applications of this sensor for Hg(2+) and biothiols determination in water samples and human plasma sample have been demonstrated with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

Scanning fluorescent microscopy is an alternative for quantitative fluorescent cell analysis.

PubMed

Varga, Viktor Sebestyén; Bocsi, József; Sipos, Ferenc; Csendes, Gábor; Tulassay, Zsolt; Molnár, Béla

2004-07-01

Fluorescent measurements on cells are performed today with FCM and laser scanning cytometry. The scientific community dealing with quantitative cell analysis would benefit from the development of a new digital multichannel and virtual microscopy based scanning fluorescent microscopy technology and from its evaluation on routine standardized fluorescent beads and clinical specimens. We applied a commercial motorized fluorescent microscope system. The scanning was done at 20 x (0.5 NA) magnification, on three channels (Rhodamine, FITC, Hoechst). The SFM (scanning fluorescent microscopy) software included the following features: scanning area, exposure time, and channel definition, autofocused scanning, densitometric and morphometric cellular feature determination, gating on scatterplots and frequency histograms, and preparation of galleries of the gated cells. For the calibration and standardization Immuno-Brite beads were used. With application of shading compensation, the CV of fluorescence of the beads decreased from 24.3% to 3.9%. Standard JPEG image compression until 1:150 resulted in no significant change. The change of focus influenced the CV significantly only after +/-5 microm error. SFM is a valuable method for the evaluation of fluorescently labeled cells. Copyright 2004 Wiley-Liss, Inc.

An ensemble and single-molecule fluorescence microscopy investigation of phase-separated monolayer films stained with Nile Red.

PubMed

Lu, Yin; Porterfield, Robyn; Thunder, Terri; Paige, Matthew F

2011-01-01

Phase-separated Langmuir-Blodgett monolayer films prepared from mixtures of arachidic acid (C19H39COOH) and perfluorotetradecanoic acid (C13F27COOH) were stained via spin-casting with the polarity sensitive phenoxazine dye Nile Red, and characterized using a combination of ensemble and single-molecule fluorescence microscopy measurements. Ensemble fluorescence microscopy and spectromicroscopy showed that Nile Red preferentially associated with the hydrogenated domains of the phase-separated films, and was strongly fluorescent in these areas of the film. These measurements, in conjunction with single-molecule fluorescence imaging experiments, also indicated that a small sub-population of dye molecules localizes on the perfluorinated regions of the sample, but that this sub-population is spectroscopically indistinguishable from that associated with the hydrogenated domains. The relative importance of selective dye adsorption and local polarity sensitivity of Nile Red for staining applications in phase-separated LB films as well as in cellular environments is discussed in context of the experimental results. Copyright © 2010 Elsevier B.V. All rights reserved.

Determination of branched chain amino acids, methionine, phenylalanine, tyrosine and alpha-keto acids in plasma and dried blood samples using HPLC with fluorescence detection.

PubMed

Kand'ár, Roman; Záková, Pavla; Jirosová, Jana; Sladká, Michaela

2009-01-01

The determination of branched chain amino acids [BCAA; valine (Val), leucine (Leu), isoleucine (Ile)], alpha-keto acids derived from BCAA [BCKA; alpha-ketoisovaleric acid (KIV), alpha-ketoisocaproic acid (KIC), alpha-ketomethylvaleric acid (KMV)], methionine (Met), phenylalanine (Phe) and tyrosine (Tyr) is currently the most reliable approach for the diagnosis of maple syrup urine disease (MSUD), hypermethioninemia, phenylketonuria (PKU) and tyrosinemia. The aim of this study was to develop rapid and simple HPLC methods for measurement of BCAA, Met, Phe, Tyr and BCKA in plasma and dried blood samples. Samples of peripheral venous blood with EDTA as anticoagulant were obtained from a group of healthy blood donors (n=70, 35 females, 27-41 years of age and 35 males, 28-43 years of age). Blood-spot samples from a group of newborns (n=80, 40 girls and 40 boys 3-5 days of age) were collected onto #903 Specimen Collection Paper and allowed to dry for at least 24 h before analysis. Prior to separation, the amino acids (AA) were derivatized with o-phthaldialdehyde (OPA) and BCKA with o-phenylenediamine (OPD). Reverse phase column chromatography (LiChroCart 125-4 Purospher RP-18e, 5 microm) was used for separation and fluorescence detection used to monitoring of effluent. For AA analysis, 25 mmol/L sodium hydrogenphosphate-methanol (90:10, v/v), pH 6.5+/-0.1 was used as mobile phase A and 100% methanol was used as mobile phase B. Measurement of BCKA used a mixture of methanol and deionized water (55:45, v/v) as mobile phase A and mobile phase B consisted of 100% methanol. Analytical performance of these methods was satisfactory for the determination of all AA and BCKA. The intra-assay and inter-assay coefficients of variation were below 10% and recovery ranged from 90%-110%. We have developed simple, rapid and selective HPLC methods with fluorescence detection for the determination of BCAA, Met, Phe, Tyr and BCKA in plasma and dried blood samples.

Boronic acid recognition of non-interacting carbohydrates for biomedical applications: increasing fluorescence signals of minimally interacting aldoses and sucralose†

PubMed Central

Resendez, Angel; Halim, Md Abdul; Singh, Jasmeet; Webb, Dominic-Luc

2017-01-01

To address carbohydrates that are commonly used in biomedical applications with low binding affinities for boronic acid based detection systems, two chemical modification methods were utilized to increase sensitivity. Modified carbohydrates were analyzed using a two component fluorescent probe based on boronic acid-appended viologen–HPTS (4,4′-o-BBV). Carbohydrates normally giving poor signals (fucose, l-rhamnose, xylose) were subjected to sodium borohydride (NaBH4) reduction in ambient conditions for 1 h yielding the corresponding sugar alcohols from fucose, l-rhamnose and xylose in essentially quantitative yields. Compared to original aldoses, apparent binding affinities were increased 4–25-fold. The chlorinated sweetener and colon permeability marker sucralose (Splenda), otherwise undetectable by boronic acids, was dechlorinated to a detectable derivative by reactive oxygen and hydroxide intermediates by the Fenton reaction or by H2O2 and UV light. This method is specific to sucralose as other common sugars, such as sucrose, do not contain any carbon-chlorine bonds. Significant fluorescence response was obtained for chemically modified sucralose with the 4,4′-o-BBV–HPTS probe system. This proof of principle can be applied to biomedical applications, such as gut permeability, malabsorption, etc. PMID:29130464

Boronic acid recognition of non-interacting carbohydrates for biomedical applications: increasing fluorescence signals of minimally interacting aldoses and sucralose.

PubMed

Resendez, Angel; Halim, Md Abdul; Singh, Jasmeet; Webb, Dominic-Luc; Singaram, Bakthan

2017-11-22

To address carbohydrates that are commonly used in biomedical applications with low binding affinities for boronic acid based detection systems, two chemical modification methods were utilized to increase sensitivity. Modified carbohydrates were analyzed using a two component fluorescent probe based on boronic acid-appended viologen-HPTS (4,4'-o-BBV). Carbohydrates normally giving poor signals (fucose, l-rhamnose, xylose) were subjected to sodium borohydride (NaBH 4 ) reduction in ambient conditions for 1 h yielding the corresponding sugar alcohols from fucose, l-rhamnose and xylose in essentially quantitative yields. Compared to original aldoses, apparent binding affinities were increased 4-25-fold. The chlorinated sweetener and colon permeability marker sucralose (Splenda), otherwise undetectable by boronic acids, was dechlorinated to a detectable derivative by reactive oxygen and hydroxide intermediates by the Fenton reaction or by H 2 O 2 and UV light. This method is specific to sucralose as other common sugars, such as sucrose, do not contain any carbon-chlorine bonds. Significant fluorescence response was obtained for chemically modified sucralose with the 4,4'-o-BBV-HPTS probe system. This proof of principle can be applied to biomedical applications, such as gut permeability, malabsorption, etc.

An Assay of Selected Serum Amino Acids in Patients with Type 2 Diabetes Mellitus.

PubMed

Drábková, Petra; Šanderová, Jana; Kovařík, Jakub; kanďár, Roman

2015-01-01

Amino acids are the building blocks of proteins. In case of insulin resistance, which is typical for type 2 diabetes mellitus (T2DM), proteolysis is increased and protein synthesis is decreased; therefore, we can observe changes in the levels of amino acids in diabetics vs. non-diabetics. The aim of this study was to find differences in the levels of selected amino acids between patients with diabetes (type 2) and a control group. Amino acids were derivatized with naphthalene-2,3-dicarboxaldehyde in the presence of potassium cyanide to form fluorescent 1-cyanobenz(f)isoindole product. Amino acids derivatives were measured using a high-performance liquid chromatography with fluorescence detection. The serum levels of glucose were determined using an automatic biochemistry analyzer, glycated hemoglobin HbA1c was measured by cation exchange chromatography. A total of 19 serum amino acids in T2DM patients and non-diabetics were measured. There were 9 amino acids, which were significantly different in these groups (p<0.05). Significantly decreased levels of arginine, asparagine, glycine, serine, threonine and significantly increased levels of alanine, isoleucine, leucine, valine in diabetics were found. Significant difference in metabolism of amino acids between diabetics and non-diabetics were observed. The altered levels of amino acids in diabetic patients could be a suitable predictor of diabetes.

High-contrast fluorescence imaging based on the polarization dependence of the fluorescence enhancement using an optical interference mirror slide.

PubMed

Yasuda, Mitsuru; Akimoto, Takuo

2015-01-01

High-contrast fluorescence imaging using an optical interference mirror (OIM) slide that enhances the fluorescence from a fluorophore located on top of the OIM surface is reported. To enhance the fluorescence and reduce the background light of the OIM, transverse-electric-polarized excitation light was used as incident light, and the transverse-magnetic-polarized fluorescence signal was detected. As a result, an approximate 100-fold improvement in the signal-to-noise ratio was achieved through a 13-fold enhancement of the fluorescence signal and an 8-fold reduction of the background light.

Dual-modality, fluorescent, PLGA encapsulated bismuth nanoparticles for molecular and cellular fluorescence imaging and computed tomography.

PubMed

Swy, Eric R; Schwartz-Duval, Aaron S; Shuboni, Dorela D; Latourette, Matthew T; Mallet, Christiane L; Parys, Maciej; Cormode, David P; Shapiro, Erik M

2014-11-07

Reports of molecular and cellular imaging using computed tomography (CT) are rapidly increasing. Many of these reports use gold nanoparticles. Bismuth has similar CT contrast properties to gold while being approximately 1000-fold less expensive. Herein we report the design, fabrication, characterization, and CT and fluorescence imaging properties of a novel, dual modality, fluorescent, polymer encapsulated bismuth nanoparticle construct for computed tomography and fluorescence imaging. We also report on cellular internalization and preliminary in vitro and in vivo toxicity effects of these constructs. 40 nm bismuth(0) nanocrystals were synthesized and encapsulated within 120 nm Poly(dl-lactic-co-glycolic acid) (PLGA) nanoparticles by oil-in-water emulsion methodologies. Coumarin-6 was co-encapsulated to impart fluorescence. High encapsulation efficiency was achieved ∼70% bismuth w/w. Particles were shown to internalize within cells following incubation in culture. Bismuth nanocrystals and PLGA encapsulated bismuth nanoparticles exhibited >90% and >70% degradation, respectively, within 24 hours in acidic, lysosomal environment mimicking media and both remained nearly 100% stable in cytosolic/extracellular fluid mimicking media. μCT and clinical CT imaging was performed at multiple X-ray tube voltages to measure concentration dependent attenuation rates as well as to establish the ability to detect the nanoparticles in an ex vivo biological sample. Dual fluorescence and CT imaging is demonstrated as well. In vivo toxicity studies in rats revealed neither clinically apparent side effects nor major alterations in serum chemistry and hematology parameters. Calculations on minimal detection requirements for in vivo targeted imaging using these nanoparticles are presented. Indeed, our results indicate that these nanoparticles may serve as a platform for sensitive and specific targeted molecular CT and fluorescence imaging.

The influence of fatty acids on theophylline binding to human serum albumin. Comparative fluorescence study

NASA Astrophysics Data System (ADS)

Maciążek-Jurczyk, M.; Sułkowska, A.; Bojko, B.; Równicka-Zubik, J.; Szkudlarek-Haśnik, A.; Zubik-Skupień, I.; Góra, A.; Dubas, M.; Korzonek-Szlacheta, I.; Wielkoszyński, T.; Żurawiński, W.; Sosada, K.

2012-04-01

Theophylline, popular diuretic, is used to treat asthma and bronchospasm. In blood it forms complexes with albumin, which is also the main transporter of fatty acids. The aim of the present study was to describe the influence of fatty acids (FA) on binding of theophylline (Th) to human serum albumin (HSA) in the high affinity binding sites. Binding parameters have been obtained on the basis of the fluorescence analysis. The data obtained for the complex of Th and natural human serum albumin (nHSA) obtained from blood of obese patients qualified for surgical removal of stomach was compared with our previous studies on the influence of FA on the complex of Th and commercially available defatted human serum albumin (dHSA).

The osmotic stress response of split influenza vaccine particles in an acidic environment.

PubMed

Choi, Hyo-Jick; Kim, Min-Chul; Kang, Sang-Moo; Montemagno, Carlo D

2014-12-01

Oral influenza vaccine provides an efficient means of preventing seasonal and pandemic disease. In this work, the stability of envelope-type split influenza vaccine particles in acidic environments has been investigated. Owing to the fact that hyper-osmotic stress can significantly affect lipid assembly of vaccine, osmotic stress-induced morphological change of split vaccine particles, in conjunction with structural change of antigenic proteins, was investigated by the use of stopped-flow light scattering (SFLS), intrinsic fluorescence, transmission electron microscopy (TEM), and hemagglutination assay. Split vaccine particles were found to exhibit a step-wise morphological change in response to osmotic stress due to double-layered wall structure. The presence of hyper-osmotic stress in acidic medium (0.3 osmolarity, pH 2.0) induced a significant level of membrane perturbation as measured by SFLS and TEM, imposing more damage to antigenic proteins on vaccine envelope than can be caused by pH-induced conformational change at acidic iso-osmotic condition. Further supports were provided by the intrinsic fluorescence and hemagglutinin activity measurements. Thus, hyper-osmotic stress becomes an important factor for determining stability of split vaccine particles in acidic medium. These results are useful in better understanding the destabilizing mechanism of split influenza vaccine particles in gastric environment and in designing oral influenza vaccine formulations.

New high-performance liquid chromatography assay for glycosyltransferases based on derivatization with anthranilic acid and fluorescence detection.

PubMed

Anumula, Kalyan Rao

2012-07-01

Assays were developed using the unique labeling chemistry of 2-aminobenzoic acid (2AA; anthranilic acid, AA) for measuring activities of both β1-4 galactosyltransferase (GalT-1) and α2-6 sialyltransferase (ST-6) by high-performance liquid chromatography (HPLC) with fluorescence detection (Anumula KR. 2006. Advances in fluorescence derivatization methods for high-performance liquid chromatographic analysis of glycoprotein carbohydrates. Anal Biochem. 350:1-23). N-Acetylglucosamine (GlcNAc) and N-acetyllactosamine were used as acceptors and uridine diphosphate (UDP)-galactose and cytidine monophosphate (CMP)-N-acetylneuraminic acid (NANA) as donors for GalT-1 and ST-6, respectively. Enzymatic products were labeled in situ with AA and were separated from the substrates on TSKgel Amide 80 column using normal-phase conditions. Enzyme units were determined from the peak areas by comparison with the concomitantly derivatized standards Gal-β1-4GlcNAc and NANA-α2-6 Gal-β1-4GlcNAc. Linearity (time and enzyme concentration), precision (intra- and interassay) and reproducibility for the assays were established. The assays were found to be useful in monitoring the enzyme activities during isolation and purification. The assays were highly sensitive and performed equal to or better than the traditional radioactive sugar-based measurements. The assay format can also be used for measuring the activity of other transferases, provided that the carbohydrate acceptors contain a reducing end for labeling. An assay for glycoprotein acceptors was developed using IgG. A short HPLC profiling method was developed for the separation of IgG glycans (biantennary G0, G1, G2, mono- and disialylated), which facilitated the determination of GalT-1 and ST-6 activities in a rapid manner. Furthermore, this profiling method should prove useful for monitoring the changes in IgG glycans in clinical settings.

Saccharide sensing molecules having enhanced fluorescent properties

DOEpatents

Satcher Jr., Joe H.; Lane, Stephen M.; Darrow, Christopher B.; Cary, Douglas R.; Tran, Joe Anh

2004-01-06

The present invention provides formulae for fluorescent compounds that have a number of properties which make them uniquely suited for use in sensors of analytes such as saccharides. The advantageous fluorescent properties include favorable excitation wavelengths, emission wavelengths, fluorescence lifetimes, and photostability. Additional advantageous properties include enhanced aqueous solubility, as well as temperature and pH sensitivity. The compound comprises an aryl or a substituted phenyl botonic acid that acts as a substrate recognition component, a fluorescence switch component, and a fluorophore. Fluorescent compounds are described that are excited at wavelengths greater than 400 nm and emit at wavelengths greater than 450 nm, which is advantageous for optical transmission through skin. The fluorophore is typically selected from transition metal-ligand complexes and thiazine, oxazine, oxazone, or oxazine-one as well as anthracene compounds. The fluorescent compound can be immobilized in a glucose permeable biocompatible polymer matrix that is implantable below the skin.

DETECTION OF GYNECOLOGICAL CANCER—Use of Fluorescence Microscopy to Show Nucleic Acids in Malignant Growth

PubMed Central

Von Bertalanffy, Ludwig; Masin, Marianna; Masin, Francis; Kaplan, Leo

1957-01-01

Early detection of malignant lesions of the cervix, a major problem in gynecology, has been made possible in more cases by the development of exfoliative cytology. Mass-screening programs have been impeded, however, by the demands on time and skill of the examiner as posed by conventional techniques. A new method in exfoliative cytology, using fluorescence microscopy, essentially reduces the time of processing as well as of scanning of specimens. Suspicious cells show flaming orange-red fluorescence of the cytoplasm on a black background, impressively distinct from normal cells and giving a warning signal to the examiner. This color reaction is based upon cytochemical changes—namely, the abundance of ribonucleic acid in vividly growing and especially malignant cells. Besides gynecological material, the method is applicable to other forms of malignant disease. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6. PMID:13460741

Size-dependent fluorescence of bioaerosols: Mathematical model using fluorescing and absorbing molecules in bacteria

DOE PAGES

Hill, Steven C.; Williamson, Chatt C.; Doughty, David C.; ...

2015-02-02

This paper uses a mathematical model of fluorescent biological particles composed of bacteria and/or proteins (mostly as in Hill et al., 2013 [23]) to investigate the size-dependence of the total fluorescence emitted in all directions. The model applies to particles which have negligible reabsorption of fluorescence within the particle. The specific particles modeled here are composed of ovalbumin and of a generic Bacillus. The particles need not be spherical, and in some cases need not be homogeneous. However, the results calculated in this paper are for spherical homogeneous particles. Light absorbing and fluorescing molecules included in the model are aminomore » acids, nucleic acids, and several coenzymes. Here the excitation wavelength is 266 nm. The emission range, 300 to 370 nm, encompasses the fluorescence of tryptophan. The fluorescence cross section (C F) is calculated and compared with one set of published measured values. We investigate power law (Ad y) approximations to C F, where d is diameter, and A and y are parameters adjusted to fit the data, and examine how y varies with d and composition, including the fraction as water. The particle's fluorescence efficiency (Q F=C F/geometric-cross-section) can be written for homogeneous particles as Q absR F, where Q abs is the absorption efficiency, and R F, the fraction of the absorbed light emitted as fluorescence, is independent of size and shape. When Q F is plotted vs. m id or mi(m r-1)d, where m=m r+im i is the complex refractive index, the plots for different fractions of water in the particle tend to overlap.« less

Diols and anions can control the formation of an exciplex between a pyridinium boronic acid with an aryl group connected via a propylene linker.

PubMed

Huang, Yan-Jun; Jiang, Yun-Bao; Bull, Steven D; Fossey, John S; James, Tony D

2010-11-21

The exciplex formation between a pyridinium boronic acid and phenyl group connected via a propylene linker can be monitored using fluorescence. Addition of pinacol affords a cyclic boronate ester with enhanced Lewis acidity that increases the strength of its cation-π stacking interaction causing a four-fold fluorescence enhancement.

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

Label-free functional nucleic acid sensors for detecting target agents

DOEpatents

Lu, Yi; Xiang, Yu

2015-01-13

A general methodology to design label-free fluorescent functional nucleic acid sensors using a vacant site approach and an abasic site approach is described. In one example, a method for designing label-free fluorescent functional nucleic acid sensors (e.g., those that include a DNAzyme, aptamer or aptazyme) that have a tunable dynamic range through the introduction of an abasic site (e.g., dSpacer) or a vacant site into the functional nucleic acids. Also provided is a general method for designing label-free fluorescent aptamer sensors based on the regulation of malachite green (MG) fluorescence. A general method for designing label-free fluorescent catalytic and molecular beacons (CAMBs) is also provided. The methods demonstrated here can be used to design many other label-free fluorescent sensors to detect a wide range of analytes. Sensors and methods of using the disclosed sensors are also provided.

Insight into the heterogeneous adsorption of humic acid fluorescent components on multi-walled carbon nanotubes by excitation-emission matrix and parallel factor analysis.

PubMed

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

2018-02-01

The heterogeneous adsorption behavior of commercial humic acid (HA) on pristine and functionalized multi-walled carbon nanotubes (MWCNTs) was investigated by fluorescence excitation-emission matrix and parallel factor (EEM- PARAFAC) analysis. The kinetics, isotherms, thermodynamics and mechanisms of adsorption of HA fluorescent components onto MWCNTs were the focus of the present study. Three humic-like fluorescent components were distinguished, including one carboxylic-like fluorophore C1 (λ ex /λ em = (250, 310) nm/428nm), and two phenolic-like fluorophores, C2 (λ ex /λ em = (300, 460) nm/552nm) and C3 (λ ex /λ em = (270, 375) nm/520nm). The Lagergren pseudo-second-order model can be used to describe the adsorption kinetics of the HA fluorescent components. In addition, both the Freundlich and Langmuir models can be suitably employed to describe the adsorption of the HA fluorescent components onto MWCNTs with significantly high correlation coefficients (R 2 > 0.94, P< 0.05). The dissimilarity in the adsorption affinity (K d ) and nonlinear adsorption degree from the HA fluorescent components to MWCNTs was clearly observed. The adsorption mechanism suggested that the π-π electron donor-acceptor (EDA) interaction played an important role in the interaction between HA fluorescent components and the three MWCNTs. Furthermore, the values of the thermodynamic parameters, including the Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°), showed that the adsorption of the HA fluorescent components on MWCNTs was spontaneous and exothermic. Copyright © 2017 Elsevier Inc. All rights reserved.

A charge transfer amplified fluorescent Hg2+ complex for detection of picric acid and construction of logic functions.

PubMed

Kumar, Manoj; Reja, Shahi Imam; Bhalla, Vandana

2012-12-07

A chemosensor 3 based on the N,N-dimethylaminocinnamaldehyde has been synthesized which shows fluorescence turn-on response with Hg(2+) ions, and the in situ prepared 3-Hg(2+) complex has been used for detection of picric acid via electrostatic interaction and construction of a combinatorial logic circuit with NOR and INHIBIT logic functions.

A fluorescence-based method for direct measurement of submicrosecond intramolecular contact formation in biopolymers: an exploratory study with polypeptides.

PubMed

Hudgins, Robert R; Huang, Fang; Gramlich, Gabriela; Nau, Werner M

2002-01-30

A fluorescent amino acid derivative (Fmoc-DBO) has been synthesized, which contains 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) as a small, hydrophilic fluorophore with an extremely long fluorescence lifetime (325 ns in H2O and 505 ns in D2O under air). Polypeptides containing both the DBO residue and an efficient fluorescence quencher allow the measurement of rate constants for intramolecular end-to-end contact formation. Bimolecular quenching experiments indicated that Trp, Cys, Met, and Tyr are efficient quenchers of DBO (k(q) = 20, 5.1, 4.5, and 3.6 x 10(8) M(-1) x s(-1) in D2O), while the other amino acids are inefficient. The quenching by Trp, which was selected as an intrinsic quencher, is presumed to involve exciplex-induced deactivation. Flexible, structureless polypeptides, Trp-(Gly-Ser)n-DBO-NH2, were prepared by standard solid-phase synthesis, and the rates of contact formation were measured through the intramolecular fluorescence quenching of DBO by Trp with time-correlated single-photon counting, laser flash photolysis, and steady-state fluorometry. Rate constants of 4.1, 6.8, 4.9, 3.1, 2.0, and 1.1 x 10(7) s(-1) for n = 0, 1, 2, 4, 6, and 10 were obtained. Noteworthy was the relatively slow quenching for the shortest peptide (n = 0). The kinetic data are in agreement with recent transient absorption studies of triplet probes for related peptides, but the rate constants are significantly larger. In contrast to the flexible structureless Gly-Ser polypeptides, the polyproline Trp-Pro4-DBO-NH2 showed insignificant fluorescence quenching, suggesting that a high polypeptide flexibility and the possibility of probe-quencher contact is essential to induce quenching. Advantages of the new fluorescence-based method for measuring contact formation rates in biopolymers include high accuracy, fast time range (100 ps-1 micros), and the possibility to perform measurements in water under air.

Fluorescence diagnostics in oncological gynecology

NASA Astrophysics Data System (ADS)

Belyaeva, Ludmila A.; Adamyan, Leila V.; Kozachenko, Vladimir P.; Stratonnikov, Alexander A.; Stranadko, Eugene F.; Loschenov, Victor B.

2003-10-01

The method of fluorescent diagnostics (FD) of tumors is a promising tool that may allow to increase sensitivity of tumor detection especially at initial stages. One of the most promising photosensitizers today is 5-aminolevulinic acid (5-ALA) that, actually, is not photosensitizer itself but precursor of protoporphyrin IX (PpIX). This paper deals with cancer diagnostics in gynecology by means of ALA-induced Pp IX laser-fluorescence spectroscopy. The tissue fluorescence spectra in vivo were studied in patients with various pathologies of ovaries, uterine and vulva after 5-aminolevulinic acid administration. It was shown that different pathologies varies in accumulation of Pp IX. Coefficient of fluorescence kf for normal tissue is not high, but exceptions are endometrium and mucous membrane of uterine tubes. Benign tumors of uterus and ovary have low values of kf, but polyps of endometrium exhibit high kf. Optical express-biopsy is important for diagnosis of ovarian cancer and micrometastatic spread. Coefficients of diagnostic contrast were determined for cancer of endometrium, cervical cancer, vulvar cancer.

Investigating Marine Dissolved Organic Matter Fluorescence Transformations with Organic Geochemical Proxies in a Growth and Degradation Experiment using Amino Acids, Amino Sugars, and Phenols

NASA Astrophysics Data System (ADS)

Shields, M. R.; Bianchi, T. S.; Osburn, C. L.; Kinsey, J. D.; Ziervogel, K.; Schnetzer, A.

2017-12-01

The origin and mechanisms driving the formation of fluorescent dissolved organic matter (FDOM) in the open ocean remain unclear. Although recent studies have attempted to deconvolve the chemical composition and source of marine FDOM, these studies have been qualitative in nature. Here, we investigate these transformations using a more quantitative biomarker approach in a controlled growth and degradation experiment. In this experiment, a natural assemblage of phytoplankton was collected off the coast of North Carolina and incubated within roller bottles containing 0.2 µm-filtered North Atlantic surface water amended with f/2 nutrients. Samples were collected at the beginning (day 0), during exponential growth (day 13), stationary (day 20), and degradation (day 62) phases of the phytoplankton incubation. Amino acids, amino sugars, and phenolic compounds of the dissolved (DOM) were measured in conjunction with enzyme assays and bacterial counts to track shifts in OM quality as FDOM formed and was then transformed throughout the experiment. The results from the chemical analyses showed that the OM composition changed significantly from the initial and exponential phases to the stationary and degradation phases of the experiment. The percentage of aromatic amino acids to the total amino acid pool increased significantly during the exponential phase of phytoplankton growth, but then decreased significantly during the stationary and degradation phases. This increase was positively correlated to the fractional contribution of the protein-like peak in fluorescence to the total FDOM fluorescence. An increase in the concentration of amino acid degradation products during the stationary and degradation phases suggests that compositional changes in OM were driven by microbial transformation. This was further supported by a concurrent increase in total enzyme activity and increase in "humic-like" components of the FDOM. These findings link the properties and formation of FDOM

Double-labeled donor probe can enhance the signal of fluorescence resonance energy transfer (FRET) in detection of nucleic acid hybridization

PubMed Central

Okamura, Yukio; Kondo, Satoshi; Sase, Ichiro; Suga, Takayuki; Mise, Kazuyuki; Furusawa, Iwao; Kawakami, Shigeki; Watanabe, Yuichiro

2000-01-01

A set of fluorescently-labeled DNA probes that hybridize with the target RNA and produce fluorescence resonance energy transfer (FRET) signals can be utilized for the detection of specific RNA. We have developed probe sets to detect and discriminate single-strand RNA molecules of plant viral genome, and sought a method to improve the FRET signals to handle in vivo applications. Consequently, we found that a double-labeled donor probe labeled with Bodipy dye yielded a remarkable increase in fluorescence intensity compared to a single-labeled donor probe used in an ordinary FRET. This double-labeled donor system can be easily applied to improve various FRET probes since the dependence upon sequence and label position in enhancement is not as strict. Furthermore this method could be applied to other nucleic acid substances, such as oligo RNA and phosphorothioate oligonucleotides (S-oligos) to enhance FRET signal. Although the double-labeled donor probes labeled with a variety of fluorophores had unexpected properties (strange UV-visible absorption spectra, decrease of intensity and decay of donor fluorescence) compared with single-labeled ones, they had no relation to FRET enhancement. This signal amplification mechanism cannot be explained simply based on our current results and knowledge of FRET. Yet it is possible to utilize this double-labeled donor system in various applications of FRET as a simple signal-enhancement method. PMID:11121494

Application of ANS fluorescent probes to identify hydrophobic sites on the surface of DREAM.

PubMed

Gonzalez, Walter G; Miksovska, Jaroslava

2014-09-01

DREAM (calsenilin or KChIP-3) is a calcium sensor involved in regulation of diverse physiological processes by interactions with multiple intracellular partners including DNA, Kv4 channels, and presenilin, however the detailed mechanism of the recognition of the intracellular partners remains unclear. To identify the surface hydrophobic surfaces on apo and Ca(2+)DREAM as a possible interaction sites for target proteins and/or specific regulators of DREAM function the binding interactions of 1,8-ANS and 2,6-ANS with DREAM were characterized by fluorescence and docking studies. Emission intensity of ANS-DREAM complexes increases upon Ca(2+) association which is consistent with an overall decrease in surface polarity. The dissociation constants for ANS binding to apoDREAM and Ca(2+)DREAM were determined to be 195±20μM and 62±4μM, respectively. Fluorescence lifetime measurements indicate that two ANS molecules bind in two independent binding sites on DREAM monomer. One site is near the exiting helix of EF-4 and the second site is located in the hydrophobic crevice between EF-3 and EF-4. 1,8-ANS displacement studies using arachidonic acid demonstrate that the hydrophobic crevice between EF-3 and EF-4 serves as a binding site for fatty acids that modulate functional properties of Kv4 channel:KChIP complexes. Thus, the C-terminal hydrophobic crevice may be involved in DREAM interactions with small hydrophobic ligands as well as other intracellular proteins. Copyright © 2014 Elsevier B.V. All rights reserved.

Solubilization of human cells by the styrene-maleic acid copolymer: Insights from fluorescence microscopy.

PubMed

Dörr, Jonas M; van Coevorden-Hameete, Marleen H; Hoogenraad, Casper C; Killian, J Antoinette

2017-11-01

Extracting membrane proteins from biological membranes by styrene-maleic acid copolymers (SMAs) in the form of nanodiscs has developed into a powerful tool in membrane research. However, the mode of action of membrane (protein) solubilization in a cellular context is still poorly understood and potential specificity for cellular compartments has not been investigated. Here, we use fluorescence microscopy to visualize the process of SMA solubilization of human cells, exemplified by the immortalized human HeLa cell line. Using fluorescent protein fusion constructs that mark distinct subcellular compartments, we found that SMA solubilizes membranes in a concentration-dependent multi-stage process. While all major intracellular compartments were affected without a strong preference, plasma membrane solubilization was found to be generally slower than the solubilization of organelle membranes. Interestingly, some plasma membrane-localized proteins were more resistant against solubilization than others, which might be explained by their presence in specific membrane domains with differing properties. Our results support the general applicability of SMA for the isolation of membrane proteins from different types of (sub)cellular membranes. Copyright © 2017 Elsevier B.V. All rights reserved.

Water-Soluble Nonconjugated Polymer Nanoparticles with Strong Fluorescence Emission for Selective and Sensitive Detection of Nitro-Explosive Picric Acid in Aqueous Medium.

PubMed

Liu, Shi Gang; Luo, Dan; Li, Na; Zhang, Wei; Lei, Jing Lei; Li, Nian Bing; Luo, Hong Qun

2016-08-24

Water-soluble nonconjugated polymer nanoparticles (PNPs) with strong fluorescence emission were prepared from hyperbranched poly(ethylenimine) (PEI) and d-glucose via Schiff base reaction and self-assembly in aqueous phase. Preparation of the PEI-d-glucose (PEI-G) PNPs was facile (one-pot reaction) and environmentally friendly under mild conditions. Also, PEI-G PNPs showed a high fluorescence quantum yield in aqueous solution, and the fluorescence properties (such as concentration- and solvent-dependent fluorescence) and origin of intrinsic fluorescence were investigated and discussed. PEI-G PNPs were then used to develop a fluorescent probe for fast, selective, and sensitive detection of nitro-explosive picric acid (PA) in aqueous medium, because the fluorescence can be easily quenched by PA whereas other nitro-explosives and structurally similar compounds only caused negligible quenching. A wide linear range (0.05-70 μM) and a low detection limit (26 nM) were obtained. The fluorescence quenching mechanism was carefully explored, and it was due to a combined effect of electron transfer, resonance energy transfer, and inner filter effect between PA and PEI-G PNPs, which resulted in good selectivity and sensitivity for PA. Finally, the developed sensor was successfully applied to detection of PA in environmental water samples.

Synthesis and characterization of citrate-based fluorescent small molecules and biodegradable polymers.

PubMed

Xie, Zhiwei; Kim, Jimin P; Cai, Qing; Zhang, Yi; Guo, Jinshan; Dhami, Ranjodh S; Li, Li; Kong, Bin; Su, Yixue; Schug, Kevin A; Yang, Jian

2017-03-01

Novel citric acid based photoluminescent dyes and biodegradable polymers are synthesized via a facile "one-pot" reaction. A comprehensive understanding of the fluorescence mechanisms of the resulting citric acid-based fluorophores is reported. Two distinct types of fluorophores are identified: a thiozolopyridine family with high quantum yield, long lifetime, and exceptional photostability, and a dioxopyridine family with relatively lower quantum yield, multiple lifetimes, and solvent-dependent band shifting behavior. Applications in molecular labeling and cell imaging were demonstrated. The above discoveries contribute to the field of fluorescence chemistry and have laid a solid foundation for further development of new fluorophores and materials that show promise in a diversity of fluorescence-based applications. Photoluminescent materials are pivotal for fluorescence based imaging, labeling and sensing applications. Understanding their fluorescence mechanism is challenging and imperative. We develop a new class of citric acid-derived fluorescent materials in forms of polymers and small molecular dyes by a one-step solvent free reaction. We discovered two different classes of citric acid-derived fluorophores. A two-ring thiozolopyridine structure demonstrates strong fluorescence and exceptional resistance to photo-bleaching. A one-ring dioxopyridine exhibits relative weak fluorescence but with intriguing excitation and solvent-dependent emission wavelength shifting. Our methodology of synthesizing citric acid-derived fluorophores and the understanding on their luminescence are instrumental to the design and production of a large number of new photoluminescent materials for biological and biomedical applications. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Non-canonical amino acids bearing thiophene and bithiophene: synthesis by an Ugi multicomponent reaction and studies on ion recognition ability.

PubMed

Esteves, Cátia I C; Raposo, M Manuela M; Costa, Susana P G

2017-05-01

Novel thienyl and bithienyl amino acids with different substituents were obtained by a multicomponent Ugi reaction between a heterocyclic aldehyde, an amine, an acid and an isocyanide. Due to the presence of the sulphur heterocycle at the side chain, these unnatural amino acids are highly emissive and bear extra electron donating atoms so they were tested for their ability to act as fluorescent probes and chemosensors in the recognition of biomedically relevant ions in acetonitrile and acetonitrile/water solutions. The results obtained from spectrophotometric/spectrofluorimetric titrations in the presence of organic and inorganic anions, and alkaline; alkaline-earth and transition metal cations indicated that the bithienyl amino acid bearing a methoxy group is a selective colorimetric chemosensor for Cu 2+ , while the other (bi)thienyl amino acids act as fluorimetric chemosensors with high sensitivity towards Fe 3+ and Cu 2+ in a metal-ligand complex with 1:2 stoichiometry. The photophysical and ion sensing properties of these amino acids confirm their potential as fluorescent probes suitable for incorporation into peptidic frameworks with chemosensory ability.

Monitoring autophagic flux by an improved tandem fluorescent-tagged LC3 (mTagRFP-mWasabi-LC3) reveals that high-dose rapamycin impairs autophagic flux in cancer cells.

PubMed

Zhou, Cuihong; Zhong, Wu; Zhou, Jun; Sheng, Fugeng; Fang, Ziyuan; Wei, Yue; Chen, Yingyu; Deng, Xiaoyan; Xia, Bin; Lin, Jian

2012-08-01

Monitoring autophagic flux is important for the analysis of autophagy. Tandem fluorescent-tagged LC3 (mRFP-EGFP-LC3) is a convenient assay for monitoring autophagic flux based on different pH stability of EGFP and mRFP fluorescent proteins. However, it has been reported that there is still weak fluorescence of EGFP in acidic environments (pH between 4 and 5) or acidic lysosomes. So it is possible that autolysosomes are labeled with yellow signals (GFP(+)RFP(+) puncta), which results in misinterpreting autophagic flux results. Therefore, it is desirable to choose a monomeric green fluorescent protein that is more acid sensitive than EGFP in the assay of autophagic flux. Here, we report on an mTagRFP-mWasabi-LC3 reporter, in which mWasabi is more acid sensitive than EGFP and has no fluorescence in acidic lysosomes. Meanwhile, mTagRFP-mWasabi-LC3ΔG was constructed as the negative control for this assay. Compared with mRFP-EGFP-LC3, our results showed that this reporter is more sensitive and accurate in detecting the accumulation of autophagosomes and autolysosomes. Using this reporter, we find that high-dose rapamycin (30 μM) will impair autophagic flux, inducing many more autophagosomes than autolysosomes in HeLa cells, while low-dose rapamycin (500 nM) has an opposite effect. In addition, other chemical autophagy inducers (cisplatin, staurosporine and Z18) also elicit much more autophagosomes at high doses than those at low doses. Our results suggest that the dosage of chemical autophagy inducers would obviously influence autophagic flux in cells.

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.

Fluorescence enhancement of fluorescent unnatural streptavidin by binding of a biotin analogue with spacer tail and its application to biotin sensing.

PubMed

Zhu, Xianwei; Shinohara, Hiroaki

2014-01-01

We designed a novel molecular biosensing system for the detection of biotin, an important vitamin by the combination of fluorescent unnatural streptavidin with a commercialized biotin-(AC5)2-hydrazide. A fluorescent unnatural amino acid, BODIPY-FL-aminophenylalanine (BFLAF), was position-specifically incorporated into Trp120 of streptavidin by four-base codon method. Fluorescence of the Trp120BFLAF mutant streptavidin was enhanced by the addition of biotin-(AC5)2-hydrazide with the concentration dependent, whereas fluorescence enhancement was not observed at all by the addition of natural biotin. It was considered that the spacer tail of biotin-(AC5)2-hydrazide may disturb the fluorescence quenching of the Trp120BFLAF by Trp79 and Trp108 of the neighbor subunit. Therefore, biotin sensing was carried out by the competitive binding reaction of biotin-(AC5)2-hydrazide and natural biotin to the fluorescent mutant streptavidin. The fluorescence intensity decreased by increasing free biotin concentration. The result suggested that molecular biosensor for small ligand could be successfully designed by the pair of fluorescent mutant binding protein and ligand analogue.

Quantitative fluorescence in intracranial tumor: implications for ALA-induced PpIX as an intraoperative biomarker

PubMed Central

Valdés, Pablo A.; Leblond, Frederic; Kim, Anthony; Harris, Brent T.; Wilson, Brian C.; Fan, Xiaoyao; Tosteson, Tor D.; Hartov, Alex; Ji, Songbai; Erkmen, Kadir; Simmons, Nathan E.; Paulsen, Keith D.; Roberts, David W.

2011-01-01

Object Accurate discrimination between tumor and normal tissue is crucial for optimal tumor resection. Qualitative fluorescence of protoporphyrin IX (PpIX), synthesized endogenously following δ-aminolevulinic acid (ALA) administration, has been used for this purpose in high-grade glioma (HGG). The authors show that diagnostically significant but visually imperceptible concentrations of PpIX can be quantitatively measured in vivo and used to discriminate normal from neoplastic brain tissue across a range of tumor histologies. Methods The authors studied 14 patients with diagnoses of low-grade glioma (LGG), HGG, meningioma, and metastasis under an institutional review board–approved protocol for fluorescence-guided resection. The primary aim of the study was to compare the diagnostic capabilities of a highly sensitive, spectrally resolved quantitative fluorescence approach to conventional fluorescence imaging for detection of neoplastic tissue in vivo. Results A significant difference in the quantitative measurements of PpIX concentration occurred in all tumor groups compared with normal brain tissue. Receiver operating characteristic (ROC) curve analysis of PpIX concentration as a diagnostic variable for detection of neoplastic tissue yielded a classification efficiency of 87% (AUC = 0.95, specificity = 92%, sensitivity = 84%) compared with 66% (AUC = 0.73, specificity = 100%, sensitivity = 47%) for conventional fluorescence imaging (p < 0.0001). More than 81% (57 of 70) of the quantitative fluorescence measurements that were below the threshold of the surgeon's visual perception were classified correctly in an analysis of all tumors. Conclusions These findings are clinically profound because they demonstrate that ALA-induced PpIX is a targeting biomarker for a variety of intracranial tumors beyond HGGs. This study is the first to measure quantitative ALA-induced PpIX concentrations in vivo, and the results have broad implications for guidance during resection of

Fluorescent rhodanine-3-acetic acids visualize neurofibrillary tangles in Alzheimer's disease brains.

PubMed

Anumala, Upendra Rao; Gu, Jiamin; Lo Monte, Fabio; Kramer, Thomas; Heyny-von Haußen, Roland; Hölzer, Jana; Goetschy-Meyer, Valerie; Schön, Christian; Mall, Gerhard; Hilger, Ingrid; Czech, Christian; Herms, Jochen; Schmidt, Boris

2013-09-01

There is a high demand for the development of an imaging agent for neurofibrillary tangles (NFTs) detection in Alzheimer's diagnosis. In the present study, a series of rhodanine-3-acetic acids was synthesized and evaluated for fluorescence imaging of NFTs in brain tissues of AD patients. Five out of seven probes have shown excellent binding affinity to NFTs over amyloid plaques in the Thiazine red R displacement assay. However, the selectivity in this in vitro assay is not confirmed by the histopathological evaluation, which indicates significant differences in the binding sites in the assays. Probe 6 showed binding affinity (IC50=19nM) to tau aggregates which is the highest among this series. Probes 2, 3, 4 and 5 display IC50 values of lower than 100nM to tau aggregates to displace Thiazine red R. Evaluation of the cytotoxicity of these five probes with human liver carcinoma cells revealed that these compounds excert negligible cytotoxicity. The in vivo studies with zebrafish embryos confirmed negligible cytotoxicity at 24 and 72h post fertilization. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modified Facile Synthesis for Quantitatively Fluorescent Carbon Dots.

PubMed

Hou, Xiaofang; Hu, Yin; Wang, Ping; Yang, Liju; Al Awak, Mohamad M; Tang, Yongan; Twara, Fridah K; Qian, Haijun; Sun, Ya-Ping

2017-10-01

A simple yet consequential modification was made to the popular carbonization processing of citric acid - polyethylenimine precursor mixtures to produce carbon dots (CDots). The modification was primarily on pushing the carbonization processing a little harder at a higher temperature, such as the hydrothermal processing condition of around 330 °C for 6 hours. The CDots thus produced are comparable in spectroscopic and other properties to those obtained in other more controlled syntheses including the deliberate chemical functionalization of preprocessed and selected small carbon nanoparticles, demonstrating the consistency in CDots and reaffirming their general definition as carbon nanoparticles with surface passivation by organic or other species. Equally significant is the finding that the modified processing of citric acid - polyethylenimine precursor mixtures could yield CDots of record-setting fluorescence performance, approaching the upper limit of being quantitatively fluorescent. Thus, the reported work serves as a demonstration on not only the need in selecting the right processing conditions and its associated opportunities in one-pot syntheses of CDots, but also the feasibility in pursuing the preparation of quantitatively fluorescent CDots, which represents an important milestone in the development and understanding of these fluorescent carbon nanomaterials.

Effects of selenite on chlorophyll fluorescence, starch content and fatty acid in the duckweed Landoltia punctata.

PubMed

Zhong, Yu; Li, Yang; Cheng, Jay J

2016-09-01

Developing a Se-enriched feed for animal has become a considerable effort. In this study, Landoltia punctata 7449 was grown over a 12 day period under concentrations of selenite (Na2SeO3) from 0 to 80 μmol L(-1). The growth rate, the chlorophyll fluorescence, the starch content and fatty acid were measured. Se at low concentrations of ≤20 μmol L(-1) had positive effects also on growth rate, fatty acid content and yield of the L. punctata. The appropriate Se treatment enhanced the activity of the photosynthetic system by increasing Fv, Fm, Fv/Fm and Fv/Fo and decreasing Fo. However, negative impact to the L. punctata was observed when the duckweed was exposed to high Se concentrations (≥40 μmol L(-1)). Significant increases in starch content in the duckweed were observed after Se application. The present study suggests that the changes in growth rate, the photosynthetic system, the starch content and the fatty acid were closely associated with the application of Se. An increased Se concentration (0-20 μmol L(-1)) in duckweed could positively induce photosynthesis, thereby increasing the yield of L. punctata and could be a resource for high nutritive quality Se-enrich feed.

Synthesis of fluorescent carbon dots by a microwave heating process: structural characterization and cell imaging applications

NASA Astrophysics Data System (ADS)

Stefanakis, Dimitrios; Philippidis, Aggelos; Sygellou, Labrini; Filippidis, George; Ghanotakis, Demetrios; Anglos, Demetrios

2014-10-01

Two types of highly fluorescent carbon dots (C-dots) were prepared by a single-step procedure based on microwave heating citric acid and 6-aminocaproic acid or citric acid and urea in an aqueous solution. The small size of the isolated carbon dots along with their strong absorption in the UV and their excitation wavelength-dependent fluorescence render them ideal nanomaterials for biomedical applications (imaging and sensing). The structure and properties of the two types of C-dot materials were studied using a series of spectroscopic techniques. The ability of the C-dots to be internalized by HeLa cells was demonstrated via 3-photon fluorescence microscopy imaging.

Enantioseparations of amino acids by capillary array electrophoresis with 532 nm laser induced fluorescence detection.

PubMed

Liu, Kaiying; Wang, Li

2013-06-21

Capillary array electrophoresis (CAE) is a promising technique for multiple enantiomeric separations. Carboxytetramethylrhodamine succinimidyl ester (TAMRA SE), a rhodamine-core fluorescent probe, has rarely been applied as an original precolumn derivatization reagent for chiral amino acid (AA) analysis so far. For these purposes, high-throughput enantiomeric separations of 12 TAMRA SE-AAs by a home-made 532 nm CAE-LIF scanner are presented. The effect of cyclodextrins (CDs) and a variety of organic modifiers was quickly investigated. Baseline separations were achieved in 100 mM Tris-borate buffer (pH 10.0) containing 2 mM β-CD and 10 mM hexamethylenediamine (HDA). Multiple determination of the enantiomeric excess (ee) in non-racemic mixtures of alanine is successfully presented. Copyright © 2013 Elsevier B.V. All rights reserved.

A Simple and Selective Fluorescent Sensor Chip for Indole-3-Butyric Acid in Mung Bean Sprouts Based on Molecularly Imprinted Polymer Coatings

PubMed Central

Chang, Jiahua; Bahethan, Bota; Muhammad, Turghun; Yakup, Burabiye; Abbas, Mamatimin

2017-01-01

In this paper, we report the preparation of molecularly imprinted polymer coatings on quartz chips for selective solid-phase microextraction and fluorescence sensing of the auxin, indole-3-butyric acid. The multiple copolymerization method was used to prepare polymer coatings on silylated quartz chips. The polymer preparation conditions (e.g., the solvent, monomer, and cross-linker) were investigated systemically to enhance the binding performance of the imprinted coatings. Direct solid-phase fluorescence measurements on the chips facilitated monitoring changes in coating performance. The average binding capacity of an imprinted polymer coated chip was approximately 152.9 µg, which was higher than that of a non-imprinted polymer coated chip (60.8 µg); the imprinted coatings showed the highest binding to IBA among the structural analogues, indicating that the coatings possess high selectivity toward the template molecule. The developed method was used for the determination of the auxin in mung bean extraction, and the recovery was found to be in the range of 91.5% to 97.5%, with an RSD (n = 3) of less than 7.4%. Thus, the present study provides a simple method for fabricating a fluorescent sensor chip for selective analysis. PMID:28837081

An investigation of nonsimultaneous laser-induced fluorescence

NASA Technical Reports Server (NTRS)

Fletcher, D. G.

1993-01-01

An alternative to simultaneous, two-line laser-induced fluorescence for thermodynamic property measurement is presented. This spectroscopic approach is similar to multiple-overheat hot-wire anemometry and is based on laser excitation of different fluorescence transitions for separate, sequential wind tunnel runs. Both fluctuating and mean thermodynamic property measurements seem to be achievable with this method without exciting the transitions during the same laser pulse.

Pharmacokinetics of endogenous porphyrins induced by 5-aminolevulinic acid as observed by means of laser-induced fluorescence from several organs of tumor-bearing mice

NASA Astrophysics Data System (ADS)

Sroka, Ronald; Baumgartner, Reinhold; Beyer, Wolfgang; Gossner, Liebwin; Sassy, T.; Stocker, Susanne

1995-04-01

Photodynamic therapy (PDT) and photodynamic diagnosis (PDD) add support to efficient treatment modalities of superficial and early stage cancer. Recently 5-aminolevulinic acid (5-ALA), a precursor of hemoglobin in the hem biosynthetic pathway, was used to stimulate endogenous porphyrin production. The time dependency of 5-ALA induced porphyrin fluorescence has been investigated on several normal tissues as well as on a tumor in an in-vivo tumor model (human gastrointestinal adenocarcinoma Grade II, UICC IIa). 5-ALA has been administered intravenously at a concentration of 50 mg/(kg bw). With respect to a certain time schedule the animals were sacrificed and 12 different organs as well as the tumor were removed. Using laser-induced fluorescence techniques the emission spectra in the range of (lambda) equals (550-750) nm were detected from the tissues after excitation with light of the wavelength (lambda) equals (411 +/- 4) nm. For quantitative evaluation the integral fluorescence intensity at (lambda) equals (635 +/- 2) nm of the porphyrin specific spectra has been determined. All tissues showed porphyrin fluorescence, while brightest fluorescence has been detected from the tumor. With respect to the other tissues the relative tumor selectivity showed a maximum ratio at 406 h post injection. The kinetics of the porphyrin fluorescence intensity of the organs follow different time dependencies. Simple mathematical pharmacokinetic models are developed and discussed.

UV/blue light-induced fluorescence for assessing apple maturity

NASA Astrophysics Data System (ADS)

Noh, Hyun Kwon; Lu, Renfu

2005-11-01

Chlorophyll fluorescence has been researched for assessing fruit post-harvest quality and condition. The objective of this preliminary research was to investigate the potential of fluorescence spectroscopy for measuring apple fruit quality. Ultraviolet (UV) and blue light was used as an excitation source for inducing fluorescence in apples. Fluorescence spectra were measured from 'Golden Delicious' (GD) and 'Red Delicious' (RD) apples by using a visible/near-infrared spectrometer after one, three, and five minutes of continuous UV/blue light illumination. Standard destructive tests were performed to measure fruit firmness, skin and flesh color, soluble solids and acid content from the apples. Calibration models for each of the three illumination time periods were developed to predict fruit quality indexes. The results showed that fluorescence emission decreased steadily during the first three minutes of UV/blue light illumination and was stable within five minutes. The differences were minimal in the model prediction results based on fluorescence data at one, three or five minutes of illumination. Overall, better predictions were obtained for apple skin chroma and hue and flesh hue with values for the correlation coefficient of validation between 0.80 and 0.90 for both GD and RD. Relatively poor predictions were obtained for fruit firmness, soluble solids content, titrational acid, and flesh chroma. This research demonstrated that fluorescence spectroscopy is potentially useful for assessing selected quality attributes of apple fruit and further research is needed to improve fluorescence measurements so that better predictions of fruit quality can be achieved.

Highly thermostable fluorescent proteins

DOEpatents

Bradbury, Andrew M [Santa Fe, NM; Waldo, Geoffrey S [Santa Fe, NM; Kiss, Csaba [Los Alamos, NM

2011-11-29

Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

Highly thermostable fluorescent proteins

DOEpatents

Bradbury, Andrew M [Santa Fe, NM; Waldo, Geoffrey S [Santa Fe, NM; Kiss, Csaba [Los Alamos, NM

2011-03-22

Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

Highly thermostable fluorescent proteins

DOEpatents

Bradbury, Andrew M [Santa Fe, NM; Waldo, Geoffrey S [Santa Fe, NM; Kiss, Csaba [Los Alamos, NM

2012-05-01

Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

An Iodine Fluorescence Quenching Clock Reaction

NASA Astrophysics Data System (ADS)

Weinberg, Richard B.

2007-05-01

A fluorescent clock reaction is described that is based on the principles of the Landolt iodine reaction but uses the potent fluorescence quenching properties of triiodide to abruptly extinguish the ultraviolet fluorescence of optical brighteners present in liquid laundry detergents. The reaction uses easily obtained household products. One variation illustrates the sequential steps and mechanisms of the reaction; other variations maximize the dramatic impact of the demonstration; and a variation that uses liquid detergent in the Briggs Rauscher reaction yields a striking oscillating luminescence. The iodine fluorescence quenching clock reaction can be used in the classroom to explore not only the principles of redox chemistry and reaction kinetics, but also the photophysics of fluorescent pH probes and optical quenching.

Capillary electrophoresis with laser-induced fluorescence detection for studying amino acid uptake by yeast during beer fermentation.

PubMed

Turkia, Heidi; Sirén, Heli; Penttilä, Merja; Pitkänen, Juha-Pekka

2015-01-01

The amino acid composition of cultivation broth is known to affect the biomass accumulation, productivity, and vitality of yeast during cultivation. A separation method based on capillary electrophoresis with laser-induced fluorescence (LIF) detection was developed for the determination of amino acid consumption by Saccharomyces cerevisiae during beer fermentation. Intraday relative standard deviations were less than 2.1% for migration times and between 2.9% and 9.9% for peak areas. Interday relative standard deviations were less than 2.5% for migration times and between 4.4% and 18.9% for peak areas. The quantification limit was even as low as 62.5 pM which equals to below attomole level detection. The method was applied to study the rate of amino acid utilization during beer fermentation. Copyright © 2014 Elsevier B.V. All rights reserved.

Study on the interaction between cinnamic acid and lysozyme

NASA Astrophysics Data System (ADS)

Zhang, Hong-Mei; Chen, Jian; Zhou, Qiu-Hua; Shi, Yue-Qin; Wang, Yan-Qing

2011-02-01

The interaction between lysozyme and cinnamic acid was investigated systematically by ultraviolet-vis absorbance, circular dichroism, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques at pH 7.40. The binding constants, quenching mechanism, and the number of binding sites were determined by the quenching of lysozyme fluorescence in presence of cinnamic acid. The results showed that the fluorescence quenching of lysozyme by cinnamic acid was a result of the formation of cinnamic acid-lysozyme complex. The hydrophobic and electrostatic interactions played major roles in stabilizing the complex; the distance r between donor and acceptor was obtained to be 2.07 nm according to Förster's theory; the effect of cinnamic acid on the conformation of lysozyme was analyzed using synchronous fluorescence, circular dichroism and three-dimensional fluorescence spectra.

Nitrogen-doped carbon quantum dots as a fluorescence probe combined with magnetic solid-phase extraction purification for analysis of folic acid in human serum.

PubMed

Wang, Meng; Jiao, Yang; Cheng, Chunsheng; Hua, Jianhao; Yang, Yaling

2017-12-01

A novel and sensitive method based on nitrogen-doped carbon quantum dots as a fluorescence probe coupled with magnetic solid-phase extraction (MSPE) purification for analysis of folic acid (FA) in human serum samples has been established for the first time. In the developed system, magnetic nanoparticles coated with hexanoic acid (Fe 3 O 4 @C 6 ) were synthesized by a one-step chemical co-precipitation method with good magnetic properties and dispersibility for sample purification, and it is better to be separated from the sample. High fluorescence nitrogen-doped carbon quantum dots (N-CQDs), simply prepared using a one-step hydrothermal method with nitrilotriacetic acid, could be selectively quenched by FA. Based on this phenomenon, a fluorescence assay was proposed for specific determination of FA. Various operational experiment parameters have been studied and optimized in detail. Under the optimum experimental conditions, the detection limit of the proposed method for FA was evaluated to be 0.5 nM (S/N = 3), while the relative standard deviation (RSD) was 1.2% (n = 6). Finally, the proposed method was applied for determination of trace levels of FA from human serum samples and quantitative recoveries were achieved within the range of 95.7-103.5%. All of the results showed that the proposed method had significant application in further research. Graphical abstract Schematic of synthesis of N-CQDs and schematic of suggested mode for analysis of folic acid (FA).

Properties of a fluorescent bezafibrate derivative (DNS-X). A new tool to study peroxisome proliferation and fatty acid beta-oxidation.

PubMed

Berlot, J P; Lutz, T; Cherkaoui Malki, M; Nicolas-Frances, V; Jannin, B; Latruffe, N

2000-12-01

The first peroxisome proliferator-activated receptor (PPAR) was cloned in 1990 by Issemann and Green. Many studies have reported the importance of this receptor in the control of gene expression of enzymes involved in lipid metabolic pathways including mitochondrial and peroxisomal fatty acid beta-oxidation, lipoprotein structure [apolipoprotein (apo) A2, apo CIII], and fatty acid synthase. By using radiolabeled molecules, it was shown that peroxisome proliferators bind and activate PPAR. As an alternative method, we developed a fluorescent dansyl (1-dimethylaminonaphthalene-5-sulfonyl) derivative peroxisome proliferator from bezafibrate (DNS-X), a hypolipidemic agent that exhibits an in vitro peroxisome proliferative activity on rat Fao-hepatic derived cultured cells. However, until now, the effect of this new compound on the liver of animals and subcellular localization was unknown. In addition to in vivo rat studies, we present a more efficient large-scale technique of DNS-X purification. Treating rats (DNS-X in the diet at 0.3% w/w) for 6 d leads to a hepatomegaly and a marked increase in liver peroxisomal palmitoyl-CoA oxidase activity. We also developed a method to localize and quantify DNS-X in tissues or cell compartment organelles. The primarily cytosolic distribution of DNS-X was confirmed by direct visualization using fluorescence microscopy of cultured Fao cells. Finally, transfection assay demonstrated that DNS-X enhanced the PPAR alpha activity as well as other peroxisome proliferators do.

The Value of 5-Aminolevulinic Acid in Low-grade Gliomas and High-grade Gliomas Lacking Glioblastoma Imaging Features: An Analysis Based on Fluorescence, Magnetic Resonance Imaging, 18F-Fluoroethyl Tyrosine Positron Emission Tomography, and Tumor Molecular Factors.

PubMed

Jaber, Mohammed; Wölfer, Johannes; Ewelt, Christian; Holling, Markus; Hasselblatt, Martin; Niederstadt, Thomas; Zoubi, Tarek; Weckesser, Matthias; Stummer, Walter

2016-03-01

Approximately 20% of grade II and most grade III gliomas fluoresce after 5-aminolevulinic acid (5-ALA) application. Conversely, approximately 30% of nonenhancing gliomas are actually high grade. The aim of this study was to identify preoperative factors (ie, age, enhancement, 18F-fluoroethyl tyrosine positron emission tomography [F-FET PET] uptake ratios) for predicting fluorescence in gliomas without typical glioblastomas imaging features and to determine whether fluorescence will allow prediction of tumor grade or molecular characteristics. Patients harboring gliomas without typical glioblastoma imaging features were given 5-ALA. Fluorescence was recorded intraoperatively, and biopsy specimens collected from fluorescing tissue. World Health Organization (WHO) grade, Ki-67/MIB-1 index, IDH1 (R132H) mutation status, O-methylguanine DNA methyltransferase (MGMT) promoter methylation status, and 1p/19q co-deletion status were assessed. Predictive factors for fluorescence were derived from preoperative magnetic resonance imaging and F-FET PET. Classification and regression tree analysis and receiver-operating-characteristic curves were generated for defining predictors. Of 166 tumors, 82 were diagnosed as WHO grade II, 76 as grade III, and 8 as glioblastomas grade IV. Contrast enhancement, tumor volume, and F-FET PET uptake ratio >1.85 predicted fluorescence. Fluorescence correlated with WHO grade (P < .001) and Ki-67/MIB-1 index (P < .001), but not with MGMT promoter methylation status, IDH1 mutation status, or 1p19q co-deletion status. The Ki-67/MIB-1 index in fluorescing grade III gliomas was higher than in nonfluorescing tumors, whereas in fluorescing and nonfluorescing grade II tumors, no differences were noted. Age, tumor volume, and F-FET PET uptake are factors predicting 5-ALA-induced fluorescence in gliomas without typical glioblastoma imaging features. Fluorescence was associated with an increased Ki-67/MIB-1 index and high-grade pathology. Whether

Development of an Ultrasonication-Assisted Extraction Based HPLC With a Fluorescence Method for Sensitive Determination of Aflatoxins in Highly Acidic Hibiscus sabdariffa.

PubMed

Liu, Xiaofei; Ying, Guangyao; Sun, Chaonan; Yang, Meihua; Zhang, Lei; Zhang, Shanshan; Xing, Xiaoyan; Li, Qian; Kong, Weijun

2018-01-01

The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD) after ultrasonication-assisted extraction, immunoaffinity column (IAC) clean-up and on-line post-column photochemical derivatization (PCD). Aflatoxins B 1 , B 2 , G 1 , G 2 were extracted from samples by using methanol/water (70:30, v/v ) with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0) to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity ( R > 0.999), sensitivity (limits of detection (LODs) and limits of quantitation (LOQs) of 0.15-0.65 and 0.53-2.18 μg/kg, respectively), precision (RSD <11%), stability (RSD of 0.2-3.6%), and accuracy (recovery rates of 86.0-102.3%), which all met the stipulated analytical requirements. Analysis of 28 H. sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B 1 (AFB 1 ) at 3.11 μg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc.

Fluorescence Excitation-Emission Matrix Regional Integration to Quantify Spectra for Dissolved Organic Matter

USGS Publications Warehouse

Chen, W.; Westerhoff, P.; Leenheer, J.A.; Booksh, K.

2003-01-01

Excitation-emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in water and soil. However, interpreting the >10,000 wavelength-dependent fluorescence intensity data points represented in EEMs has posed a significant challenge. Fluorescence regional integration, a quantitative technique that integrates the volume beneath an EEM, was developed to analyze EEMs. EEMs were delineated into five excitation-emission regions based on fluorescence of model compounds, DOM fractions, and marine waters or freshwaters. Volumetric integration under the EEM within each region, normalized to the projected excitation-emission area within that region and dissolved organic carbon concentration, resulted in a normalized region-specific EEM volume (??i,n). Solid-state carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FTIR) analysis, ultraviolet-visible absorption spectra, and EEMs were obtained for standard Suwannee River fulvic acid and 15 hydrophobic or hydrophilic acid, neutral, and base DOM fractions plus nonfractionated DOM from wastewater effluents and rivers in the southwestern United States. DOM fractions fluoresced in one or more EEM regions. The highest cumulative EEM volume (??T,n = ????i,n) was observed for hydrophobic neutral DOM fractions, followed by lower ??T,n values for hydrophobic acid, base, and hydrophilic acid DOM fractions, respectively. An extracted wastewater biomass DOM sample contained aromatic protein- and humic-like material and was characteristic of bacterial-soluble microbial products. Aromatic carbon and the presence of specific aromatic compounds (as indicated by solid-state 13C NMR and FTIR data) resulted in EEMs that aided in differentiating wastewater effluent DOM from drinking water DOM.

Ultrasensitive fluorescence immunoassay for detection of ochratoxin A using catalase-mediated fluorescence quenching of CdTe QDs

NASA Astrophysics Data System (ADS)

Huang, Xiaolin; Zhan, Shengnan; Xu, Hengyi; Meng, Xianwei; Xiong, Yonghua; Chen, Xiaoyuan

2016-04-01

Herein, for the first time we report an improved competitive fluorescent enzyme linked immunosorbent assay (ELISA) for the ultrasensitive detection of ochratoxin A (OTA) by using hydrogen peroxide (H2O2)-induced fluorescence quenching of mercaptopropionic acid-modified CdTe quantum dots (QDs). In this immunoassay, catalase (CAT) was labeled with OTA as a competitive antigen to connect the fluorescence signals of the QDs with the concentration of the target. Through the combinatorial use of H2O2-induced fluorescence quenching of CdTe QDs as a fluorescence signal output and the ultrahigh catalytic activity of CAT to H2O2, our proposed method could be used to perform a dynamic linear detection of OTA ranging from 0.05 pg mL-1 to 10 pg mL-1. The half maximal inhibitory concentration was 0.53 pg mL-1 and the limit of detection was 0.05 pg mL-1. These values were approximately 283- and 300-folds lower than those of horseradish peroxidase (HRP)-based conventional ELISA, respectively. The reported method is accurate, highly reproducible, and specific against other mycotoxins in agricultural products as well. In summary, the developed fluorescence immunoassay based on H2O2-induced fluorescence quenching of CdTe QDs can be used for the rapid and highly sensitive detection of mycotoxins or haptens in food safety monitoring.Herein, for the first time we report an improved competitive fluorescent enzyme linked immunosorbent assay (ELISA) for the ultrasensitive detection of ochratoxin A (OTA) by using hydrogen peroxide (H2O2)-induced fluorescence quenching of mercaptopropionic acid-modified CdTe quantum dots (QDs). In this immunoassay, catalase (CAT) was labeled with OTA as a competitive antigen to connect the fluorescence signals of the QDs with the concentration of the target. Through the combinatorial use of H2O2-induced fluorescence quenching of CdTe QDs as a fluorescence signal output and the ultrahigh catalytic activity of CAT to H2O2, our proposed method could be used to

Non-invasive In Vivo Fluorescence Optical Imaging of Inflammatory MMP Activity Using an Activatable Fluorescent Imaging Agent.

PubMed

Schwenck, Johannes; Maier, Florian C; Kneilling, Manfred; Wiehr, Stefan; Fuchs, Kerstin

2017-05-08

This paper describes a non-invasive method for imaging matrix metalloproteinases (MMP)-activity by an activatable fluorescent probe, via in vivo fluorescence optical imaging (OI), in two different mouse models of inflammation: a rheumatoid arthritis (RA) and a contact hypersensitivity reaction (CHR) model. Light with a wavelength in the near infrared (NIR) window (650 - 950 nm) allows a deeper tissue penetration and minimal signal absorption compared to wavelengths below 650 nm. The major advantages using fluorescence OI is that it is cheap, fast and easy to implement in different animal models. Activatable fluorescent probes are optically silent in their inactivated states, but become highly fluorescent when activated by a protease. Activated MMPs lead to tissue destruction and play an important role for disease progression in delayed-type hypersensitivity reactions (DTHRs) such as RA and CHR. Furthermore, MMPs are the key proteases for cartilage and bone degradation and are induced by macrophages, fibroblasts and chondrocytes in response to pro-inflammatory cytokines. Here we use a probe that is activated by the key MMPs like MMP-2, -3, -9 and -13 and describe an imaging protocol for near infrared fluorescence OI of MMP activity in RA and control mice 6 days after disease induction as well as in mice with acute (1x challenge) and chronic (5x challenge) CHR on the right ear compared to healthy ears.

Capillary electrophoresis with laser-induced fluorescence detection: a sensitive method for monitoring extracellular concentrations of amino acids in the periaqueductal grey matter.

PubMed

Bergquist, J; Vona, M J; Stiller, C O; O'Connor, W T; Falkenberg, T; Ekman, R

1996-03-01

The use of capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) for the analysis of microdialysate samples from the periaqueductal grey matter (PAG) of freely moving rats is described. By employing 3-(4-carboxybenzoyl)-2-quinoline-carboxaldehyde (CBQCA) as a derivatization agent, we simultaneously monitored the concentrations of 8 amino acids (arginine, glutamine, valine, gamma-amino-n-butyric acid (GABA), alanine, glycine, glutamate, and aspartate), with nanomolar and subnanomolar detection limits. Two of the amino acids (GABA and glutamate) were analysed in parallel by conventional high-performance liquid chromatography (HPLC) in order to directly compare the two analytical methods. Other CE methods for analysis of microdialysate have been previously described, and this improved method offers greater sensitivity, ease of use, and the possibility to monitor several amino acids simultaneously. By using this technique together with an optimised form of microdialysis technique, the tiny sample consumption and the improved detection limits permit the detection of fast and transient transmitter changes.

Photosensitizer fluorescence and singlet oxygen luminescence as dosimetric predictors of topical 5-aminolevulinic acid photodynamic therapy induced clinical erythema.

PubMed

Mallidi, Srivalleesha; Anbil, Sriram; Lee, Seonkyung; Manstein, Dieter; Elrington, Stefan; Kositratna, Garuna; Schoenfeld, David; Pogue, Brian; Davis, Steven J; Hasan, Tayyaba

2014-02-01

The need for patient-specific photodynamic therapy (PDT) in dermatologic and oncologic applications has triggered several studies that explore the utility of surrogate parameters as predictive reporters of treatment outcome. Although photosensitizer (PS) fluorescence, a widely used parameter, can be viewed as emission from several fluorescent states of the PS (e.g., minimally aggregated and monomeric), we suggest that singlet oxygen luminescence (SOL) indicates only the active PS component responsible for the PDT. Here, the ability of discrete PS fluorescence-based metrics (absolute and percent PS photobleaching and PS re-accumulation post-PDT) to predict the clinical phototoxic response (erythema) resulting from 5-aminolevulinic acid PDT was compared with discrete SOL (DSOL)-based metrics (DSOL counts pre-PDT and change in DSOL counts pre/post-PDT) in healthy human skin. Receiver operating characteristic curve (ROC) analyses demonstrated that absolute fluorescence photobleaching metric (AFPM) exhibited the highest area under the curve (AUC) of all tested parameters, including DSOL based metrics. The combination of dose-metrics did not yield better AUC than AFPM alone. Although sophisticated real-time SOL measurements may improve the clinical utility of SOL-based dosimetry, discrete PS fluorescence-based metrics are easy to implement, and our results suggest that AFPM may sufficiently predict the PDT outcomes and identify treatment nonresponders with high specificity in clinical contexts.

Fluorescence lifetime plate reader: Resolution and precision meet high-throughput

PubMed Central

Petersen, Karl J.; Peterson, Kurt C.; Muretta, Joseph M.; Higgins, Sutton E.; Gillispie, Gregory D.; Thomas, David D.

2014-01-01

We describe a nanosecond time-resolved fluorescence spectrometer that acquires fluorescence decay waveforms from each well of a 384-well microplate in 3 min with signal-to-noise exceeding 400 using direct waveform recording. The instrument combines high-energy pulsed laser sources (5–10 kHz repetition rate) with a photomultiplier and high-speed digitizer (1 GHz) to record a fluorescence decay waveform after each pulse. Waveforms acquired from rhodamine or 5-((2-aminoethyl)amino) naphthalene-1-sulfonic acid dyes in a 384-well plate gave lifetime measurements 5- to 25-fold more precise than the simultaneous intensity measurements. Lifetimes as short as 0.04 ns were acquired by interleaving with an effective sample rate of 5 GHz. Lifetime measurements resolved mixtures of single-exponential dyes with better than 1% accuracy. The fluorescence lifetime plate reader enables multiple-well fluorescence lifetime measurements with an acquisition time of 0.5 s per well, suitable for high-throughput fluorescence lifetime screening applications. PMID:25430092

Studying electron-PAG interactions using electron-induced fluorescence

NASA Astrophysics Data System (ADS)

Narasimhan, Amrit; Grzeskowiak, Steven; Ostrander, Jonathan; Schad, Jonathon; Rebeyev, Eliran; Neisser, Mark; Ocola, Leonidas E.; Denbeaux, Gregory; Brainard, Robert L.

2016-03-01

In extreme ultraviolet (EUV) lithography, 92 eV photons are used to expose photoresists. Typical EUV resists are organic-based and chemically amplified using photoacid generators (PAGs). Upon exposure, PAGs produce acids which catalyze reactions that result in changes in solubility. In EUV lithography, photo- and secondary electrons (energies of 10- 80 eV) play a large role in PAG acid-production. Several mechanisms for electron-PAG interactions (e.g. electron trapping, and hole-initiated chemistry) have been proposed. The aim of this study is to explore another mechanism - internal excitation - in which a bound PAG electron can be excited by receiving energy from another energetic electron, causing a reaction that produces acid. This paper explores the mechanism of internal excitation through the analogous process of electron-induced fluorescence, in which an electron loses energy by transferring that energy to a molecule and that molecule emits a photon rather than decomposing. We will show and quantify electron-induced fluorescence of several fluorophores in polymer films to mimic resist materials, and use this information to refine our proposed mechanism. Relationships between the molecular structure of fluorophores and fluorescent quantum yield may aid in the development of novel PAGs for EUV lithography.

ANTS-anchored Zn-Al-CO3-LDH particles as fluorescent probe for sensing of folic acid

NASA Astrophysics Data System (ADS)

Liu, Pengfei; Liu, Dan; Liu, Yanhuan; Li, Lei

2016-09-01

A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO3-layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn2+ ions of Zn-Al-CO3-LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO3-LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO3-LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO3 groups in ANTS-anchored on the surface of Zn-Al-CO3-LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO3-LDH particles can afford a very sensitive system for the sensing FA in aqueous solution.

Dual-Emitting Fluorescent Metal-Organic Framework Nanocomposites as a Broad-Range pH Sensor for Fluorescence Imaging.

PubMed

Chen, Haiyong; Wang, Jing; Shan, Duoliang; Chen, Jing; Zhang, Shouting; Lu, Xiaoquan

2018-05-15

pH plays an important role in understanding physiological/pathologic processes, and abnormal pH is a symbol of many common diseases such as cancer, stroke, and Alzheimer's disease. In this work, an effective dual-emission fluorescent metal-organic framework nanocomposite probe (denoted as RB-PCN) has been constructed for sensitive and broad-range detection of pH. RB-PCN was prepared by encapsulating the DBI-PEG-NH 2 -functionalized Fe 3 O 4 into Zr-MOFs and then further reacting it with rhodamine B isothiocyanates (RBITC). In RB-PCN, RBITC is capable of sensing changes in pH in acidic solutions. Zr-MOFs not only enrich the target analyte but also exhibit a fluorescence response to pH changes in alkaline solutions. Based on the above structural and compositional features, RB-PCN could detect a wide range of pH changes. Importantly, such a nanoprobe could "see" the intracellular pH changes by fluorescence confocal imaging as well as "measure" the wider range of pH in actual samples by fluorescence spectroscopy. To the best of our knowledge, this is the first time a MOF-based dual-emitting fluorescent nanoprobe has been used for a wide range of pH detection.

Biological detection and tagging using tailorable, reactive, highly fluorescent chemosensors.

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

Shepodd, Timothy J.; Zifer, Thomas; McElhanon, James Ross

2006-11-01

This program was focused on the development of a fluorogenic chemosensor family that could tuned for reaction with electrophilic (e.g. chemical species, toxins) and nucleophilic (e.g. proteins and other biological molecules) species. Our chemosensor approach utilized the fluorescent properties of well-known berberine-type alkaloids. In situ chemosensor reaction with a target species transformed two out-of-plane, weakly conjugated, short-wavelength chromophores into one rigid, planar, conjugated, chromophore with strong long wavelength fluorescence (530-560 nm,) and large Stokes shift (100-180 nm). The chemosensor was activated with an isourea group which allowed for reaction with carboxylic acid moieties found in amino acids.

Fluorescence spectroscopy of soil pellets : The use of CP/PARAFAC.

NASA Astrophysics Data System (ADS)

Mounier, Stéphane; Nicolodeli, Gustavo; Redon, Roland; Hacherouf, Kalhed; Milori, Debora M. B. P.

2014-05-01

performed in pellets (boric and humic acids mixture) using a portable system built by Embrapa Instrumentation. It comprises a diode laser (Coherent - CUBE) emitting at 405 nm (50 mW), and the detection of emission by a high sensitivity mini-spectrometer (USB4000 - Ocean Optics) using a range from 440 to 800 nm. In first step, the 3D tensors were then treated by the CP/PARAFAC algorithm to decompose the signal response after removing the diffusion signal : three components were extracted with a CORCONDIA over 60%. The first component can be associate an artefact of the measurement or boric acid fluorescence, the second and third component could the related to the two different fluorescence contributions of tryptophan molecule, one with central excitation/emission in 290/360 nm and other in 350/465 nm. The presence of a small quantity (i.e. few percent in mass) of humic acid (HA) is quenching drastically the TRP fluorescence. Complementary, measurements will be performed to understand this behaviour taking in account the absorption wavelength by the surface (colour) and by measuring the time life fluorescence of the samples. Humic acid fluorescence in pellets (BA and HA) cannot be observed using lamp + monochromator excitation due to low intensity of source. The same pellets were measure using LIFS system, and fluorescence intensity increased as a function of concentration of HA until occur the inner filter effect from 300 ppm, similar to the behaviour of HA in solution. Even whether solid surface measurements are easier, understanding is not yet clear. More investigation needs to be done. Moreover, it should be important to know if the use of CP/PARAFAC decomposition for such data is relevant with the trilinear model. References Milori, D.M.B.P., Galeti, H.V.A., Martin-Neto, L., Dieckow, J., González-Pérez, M., Bayer, C., Salton, J., 2006. Organic Matter Study of Whole Soil Samples Using Laser-Induced Fluorescence Spectroscopy. Soil Science Society of America Journal 70

Comparative study of protoporphyrin IX fluorescence image enhancement methods to improve an optical imaging system for oral cancer detection

NASA Astrophysics Data System (ADS)

Jiang, Ching-Fen; Wang, Chih-Yu; Chiang, Chun-Ping

2011-07-01

Optoelectronics techniques to induce protoporphyrin IX fluorescence with topically applied 5-aminolevulinic acid on the oral mucosa have been developed to noninvasively detect oral cancer. Fluorescence imaging enables wide-area screening for oral premalignancy, but the lack of an adequate fluorescence enhancement method restricts the clinical imaging application of these techniques. This study aimed to develop a reliable fluorescence enhancement method to improve PpIX fluorescence imaging systems for oral cancer detection. Three contrast features, red-green-blue reflectance difference, R/B ratio, and R/G ratio, were developed first based on the optical properties of the fluorescence images. A comparative study was then carried out with one negative control and four biopsy confirmed clinical cases to validate the optimal image processing method for the detection of the distribution of malignancy. The results showed the superiority of the R/G ratio in terms of yielding a better contrast between normal and neoplastic tissue, and this method was less prone to errors in detection. Quantitative comparison with the clinical diagnoses in the four neoplastic cases showed that the regions of premalignancy obtained using the proposed method accorded with the expert's determination, suggesting the potential clinical application of this method for the detection of oral cancer.

Superior optical nonlinearity of an exceptional fluorescent stilbene dye

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

He, Tingchao; Division of Physics and Applied Physics, Centre for Disruptive Photonic Technologies; Sreejith, Sivaramapanicker

2015-03-16

Strong multiphoton absorption and harmonic generation in organic fluorescent chromophores are, respectively, significant in many fields of research. However, most of fluorescent chromophores fall short of the full potential due to the absence of the combination of such different nonlinear upconversion behaviors. Here, we demonstrate that an exceptional fluorescent stilbene dye could exhibit efficient two- and three-photon absorption under the excitation of femtosecond pulses in solution phase. Benefiting from its biocompatibility and strong excited state absorption behavior, in vitro two-photon bioimaging and superior optical limiting have been exploited, respectively. Simultaneously, the chromophore could generate efficient three-photon excited fluorescence and third-harmonicmore » generation (THG) when dispersed into PMMA film, circumventing the limitations of classical fluorescent chromophores. Such chromophore may find application in the production of coherent light sources of higher photon energy. Moreover, the combination of three-photon excited fluorescence and THG can be used in tandem to provide complementary information in biomedical studies.« less

Detection of Low-Copy-Number Genomic DNA Sequences in Individual Bacterial Cells by Using Peptide Nucleic Acid-Assisted Rolling-Circle Amplification and Fluorescence In Situ Hybridization▿ †

PubMed Central

Smolina, Irina; Lee, Charles; Frank-Kamenetskii, Maxim

2007-01-01

An approach is proposed for in situ detection of short signature DNA sequences present in single copies per bacterial genome. The site is locally opened by peptide nucleic acids, and a circular oligonucleotide is assembled. The amplicon generated by rolling circle amplification is detected by hybridization with fluorescently labeled decorator probes. PMID:17293504

A simple chip free-flow electrophoresis for monosaccharide sensing via supermolecule interaction of boronic acid functionalized quencher and fluorescent dye.

PubMed

Yin, Xiao-Yang; Dong, Jing-Yu; Wang, Hou-Yu; Li, Si; Fan, Liu-Yin; Cao, Cheng-Xi

2013-08-01

Here, a simple micro free-flow electrophoresis (μFFE) was developed for fluorescence sensing of monosaccharide via supermolecule interaction of synthesized boronic acid functionalized benzyl viologen (ο-BBV) and fluorescent dye. The μFFE contained two open electrode cavities and an ion-exchange membrane was sandwiched between two polymethylmethacrylate plates. The experiments demonstrated the following merits of developed μFFE: (i) up to 90.5% of voltage efficiency due to high conductivity of ion-exchange membrane; (ii) a strong ability against influence of bubble produced in two electrodes due to open design of electrode cavities; and (iii) reusable and washable separation chamber (45 mm × 17 mm × 100 μm, 77 μL) avoiding the discard of μFFE due to blockage of solute precipitation in chamber. Remarkably, the μFFE was first designed for the sensing of monosaccharide via the supermolecule interaction of synthesized ο-BBV, fluorescent dye, and monosaccharide. Under the optimized conditions, the minimum concentration of monosaccharide that could be detected was 1 × 10(-11) M. Finally, the developed device was used for the detection of 0.3 mM glucose spiked in human urine. All of the results demonstrated the feasibility of monosaccharide detection via the μFFE. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stopped-flow studies of changes in fluorescence of 8-anilino-1-naphthalene sulfonic acid caused by magnesium and salt binding to yeast enolase.

PubMed

Brewer, J M

1976-12-11

Stopped-flow studies of magnesium and salt (potassium chloride and acetate) effects on yeast enolase were carried out by following 8-anilino-1-naphthalenesulfonic acid fluorescence changes. The fluorescence changes appear to be largely caused by subunit association and dissociation, though there is evidence in some reactions for large changes in fluorescence occurring within the dead time of the stopped-flow measurements. These data are combined with measurements of initial enzyme activity after incubation in various solvents with or without magnesium to obtain subunit association and dissociation rates. From these, it is concluded that magnesium and the salts act by directly changing the affinities of the subunits for each other, apparently by producing a rapid change in protein conformation.

Fluorescence Detection of KRAS2 mRNA Hybridization in Lung Cancer Cells with PNA-Peptides Containing an Internal Thiazole Orange

PubMed Central

2015-01-01

We previously developed reporter-peptide nucleic acid (PNA)-peptides for sequence-specific radioimaging and fluorescence imaging of particular mRNAs in cells and tumors. However, a direct test for PNA-peptide hybridization with RNA in the cytoplasm would be desirable. Thiazole orange (TO) dye at the 5′ end of a hybridization agent shows a strong increase in fluorescence quantum yield when stacked upon a 5′ terminal base pair, in solution and in cells. We hypothesized that hybridization agents with an internal TO could distinguish a single base mutation in RNA. Thus, we designed KRAS2 PNA-IGF1 tetrapeptide agents with an internal TO adjacent to the middle base of the 12th codon, a frequent site of cancer-initiating mutations. Our molecular dynamics calculations predicted a disordered bulge with weaker hybridization resulting from a single RNA mismatch. We observed that single-stranded PNA-IGF1 tetrapeptide agents with an internal TO showed low fluorescence, but fluorescence escalated 5–6-fold upon hybridization with KRAS2 RNA. Circular dichroism melting curves showed ∼10 °C higher Tm for fully complementary vs single base mismatch TO-PNA-peptide agent duplexes with KRAS2 RNA. Fluorescence measurements of treated human lung cancer cells similarly showed elevated cytoplasmic fluorescence intensity with fully complementary vs single base mismatch agents. Sequence-specific elevation of internal TO fluorescence is consistent with our hypothesis of detecting cytoplasmic PNA-peptide:RNA hybridization if a mutant agent encounters the corresponding mutant mRNA. PMID:25180641

Time-resolved laser fluorescence spectroscopy of organic ligands by europium: Fluorescence quenching and lifetime properties

NASA Astrophysics Data System (ADS)

Nouhi, A.; Hajjoul, H.; Redon, R.; Gagné, J. P.; Mounier, S.

2018-03-01

Time-resolved Laser Fluorescence Spectroscopy (TRLFS) has proved its usefulness in the fields of biophysics, life science and geochemistry to characterize the fluorescence probe molecule with its chemical environment. The purpose of this study is to demonstrate the applicability of this powerful technique combined with Steady-State (S-S) measurements. A multi-mode factor analysis, in particular CP/PARAFAC, was used to analyze the interaction between Europium (Eu) and Humic substances (HSs) extracted from Saint Lawrence Estuary in Canada. The Saint Lawrence system is a semi-enclosed water stream with connections to the Atlantic Ocean and is an excellent natural laboratory. CP/PARAFAC applied to fluorescence S-S data allows introspecting ligands-metal interactions and the one-site 1:1 modeling gives information about the stability constants. From the spectral signatures and decay lifetimes data given by TRLFS, one can deduce the fluorescence quenching which modifies the fluorescence and discuss its mechanisms. Results indicated a relatively strong binding ability between europium and humic substances samples (Log K value varies from 3.38 to 5.08 at pH 7.00). Using the Stern-Volmer plot, it has been concluded that static and dynamic quenching takes places in the case of salicylic acid and europium interaction while for HSs interaction only a static quenching is observed.

Novel biosensor system model based on fluorescence quenching by a fluorescent streptavidin and carbazole-labeled biotin.

PubMed

Zhu, Xianwei; Shinohara, Hiroaki; Miyatake, Ryuta; Hohsaka, Takahiro

2016-10-01

In the present study, a novel molecular biosensor system model was designed by using a couple of the fluorescent unnatural mutant streptavidin and the carbazole-labeled biotin. BODIPY-FL-aminophenylalanine (BFLAF), a fluorescent unnatural amino acid was position-specifically incorporated into Trp120 position of streptavidin by four-base codon method. On the other hand, carbazole-labeled biotin was synthesized as a quencher for the fluorescent Trp120BFLAF mutant streptavidin. The fluorescence of fluorescent Trp120BFLAF mutant streptavidin was decreased as we expected when carbazole-labeled biotin was added into the mutant streptavidin solution. Furthermore, the fluorescence decrease of Trp120BFLAF mutant streptavidin with carbazole-labeled biotin (100 nM) was recovered by the competitive addition of natural biotin. This result demonstrated that by measuring the fluorescence quenching and recovery, a couple of the fluorescent Trp120BFLAF mutant streptavidin and the carbazole-labeled biotin were successfully applicable for quantification of free biotin as a molecular biosensor system. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Nucleic acid based fluorescent sensor for mercury detection

DOEpatents

Lu, Yi; Liu, Juewen

2013-02-05

A nucleic acid enzyme comprises an oligonucleotide containing thymine bases. The nucleic acid enzyme is dependent on both Hg.sup.2+and a second ion as cofactors, to produce a product from a substrate. The substrate comprises a ribonucleotide, a deoxyribonucleotide, or both.

Glutamic acid decarboxylase isoform distribution in transgenic mouse septum: an anti-GFP immunofluorescence study.

PubMed

Verimli, Ural; Sehirli, Umit S

2016-09-01

The septum is a basal forebrain region located between the lateral ventricles in rodents. It consists of lateral and medial divisions. Medial septal projections regulate hippocampal theta rhythm whereas lateral septal projections are involved in processes such as affective functions, memory formation, and behavioral responses. Gamma-aminobutyric acidergic neurons of the septal region possess the 65 and 67 isoforms of the enzyme glutamic acid decarboxylase. Although data on the glutamic acid decarboxylase isoform distribution in the septal region generally appears to indicate glutamic acid decarboxylase 67 dominance, different studies have given inconsistent results in this regard. The aim of this study was therefore to obtain information on the distributions of both of these glutamic acid decarboxylase isoforms in the septal region in transgenic mice. Two animal groups of glutamic acid decarboxylase-green fluorescent protein knock-in transgenic mice were utilized in the experiment. Brain sections from the region were taken for anti-green fluorescent protein immunohistochemistry in order to obtain estimated quantitative data on the number of gamma-aminobutyric acidergic neurons. Following the immunohistochemical procedures, the mean numbers of labeled cells in the lateral and medial septal nuclei were obtained for the two isoform groups. Statistical analysis yielded significant results which indicated that the 65 isoform of glutamic acid decarboxylase predominates in both lateral and medial septal nuclei (unpaired two-tailed t-test p < 0.0001 for LS, p < 0.01 for MS). This study is the first to reveal the dominance of glutamic acid decarboxylase isoform 65 in the septal region in glutamic acid decarboxylase-green fluorescent protein transgenic mice.

Fluorescence spectra of blood plasma treated with ultraviolet irradiation in vivo

NASA Astrophysics Data System (ADS)

Zalesskaya, G. A.; Maslova, T. O.

2010-09-01

We have studied the fluorescence spectra of blood plasma from patients with acute coronary syndrome, and also the effect of therapeutic doses of in vivo ultraviolet blood irradiation (UBI) on the spectra. We have established that the maxima in the fluorescence spectra of the original plasma samples, obtained from unirradiated blood, are located in the wavelength interval 330-340 nm, characteristic for the fluorescence of tryptophan residues. In extracorporeal UBI ( λ = 254 nm), we observed changes in the shape and also both a blue and a red shift in the maxima of the fluorescence spectra, differing in magnitude for blood plasma samples from different patients in the test group. We show that UBI-initiated changes in the fluorescence spectra of the plasma depend on the original pathological disturbances of metabolite levels, and also on the change in the oxygen-transport function of the blood and the acid-base balance, affecting the oxidative stability of the plasma. We have concluded that UV irradiation, activating buffer systems in the blood, has an effect on the universal and specific interactions of the tryptophan residue with the amino acid residues and water surrounding it.

Adenosine-derived doped carbon dots: From an insight into effect of N/P co-doping on emission to highly sensitive picric acid sensing.

PubMed

Li, Na; Liu, Shi Gang; Fan, Yu Zhu; Ju, Yan Jun; Xiao, Na; Luo, Hong Qun; Li, Nian Bing

2018-07-12

The various synthetic routes of carbon dots (C-dots) feature a considerable step toward their potential use in chemical sensors and biotechnology. Herein, by coupling phosphorus and nitrogen element introduction, the adenosine-derived N/P co-doped C-dots with fluorescence enhancement were achieved. By separately employing adenosine, adenosine monophosphate, adenosine diphosphate, and adenosine-5'-triphosphate as precursors, the effect of N/P co-doping on the fluorescence emission is discussed in detail. The formed C-dots with adenosine monophosphate exhibited strong blue fluorescence with a high quantum yield of 33.81%. Then the C-dots were employed as a fluorescent probe and utilized to develop a fast, sensitive, and selective picric acid sensor. The fluorescence of C-dots can be quenched by picric acid immediately, giving rise to a picric acid determination down to 30 nM. The possible mechanism of fluorescence quenching was discussed, which was proved to be inner filter effect and static quenching. Moreover, this method has the potential to detect picric acid in environmental water samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Differential coulometric oxidation following post column-switching high pressure liquid chromatography for fluorescence measurement of unmetabolized folic acid in human plasma.

PubMed

Bailey, Steven W; Ayling, June E

2013-11-08

Although many countries have fortified their grain supplies with folic acid (FA) to decrease the incidence of neural tube defects, others have not due to concerns that this synthetic folate might have some adverse effects. Persistent unmetabolized FA has been found even in plasma from fasted subjects. To facilitate measurement of low levels of folic acid in human plasma, post-column coulometric oxidative cleavage was used to convert poorly fluorescent FA into a highly fluorescent compound determined to be 6-formyl-pterin. To minimize sample work-up and maximize recovery, column-switching HPLC transferred a window of eluate containing the FA from the first column (C8) onto a second column (phenyl-hexyl). The pH of two mobile phases were adjusted to be above and then below a pK of the FA α-carboxyl group, thus promoting separation from compounds coeluting from the C8-column. This permitted sample preparation using only a simple high recovery protein precipitation. Definitive identification of FA in human plasma was accomplished by duplicate injections of sample with the electrochemical voltage set above and below its half-potential. The LOD (S/N=3) was 0.10 nM. The intra- and inter-assay CV's were 2.3% and 5%, respectively. Comparison of these results with those obtained by HPLC/MS/MS with stable isotope internal standard showed a slope of 1.00 ± 0.019. This simple, sensitive, and repeatable assay facilitates a more thorough investigation of the response of various human populations to folic acid intake. Post-column differential coulometric electrochemistry can expand the variety of compounds amenable to fluorescence detection. Copyright © 2013 Elsevier B.V. All rights reserved.

Red Fluorescent Carbon Nanoparticle-Based Cell Imaging Probe.

PubMed

Ali, Haydar; Bhunia, Susanta Kumar; Dalal, Chumki; Jana, Nikhil R

2016-04-13

Fluorescent carbon nanoparticle-based probes with tunable visible emission are biocompatible, environment friendly and most suitable for various biomedical applications. However, synthesis of red fluorescent carbon nanoparticles and their transformation into functional nanoparticles are very challenging. Here we report red fluorescent carbon nanoparticle-based nanobioconjugates of <25 nm hydrodynamic size and their application as fluorescent cell labels. Hydrophobic carbon nanoparticles are synthesized via high temperature colloid-chemical approach and transformed into water-soluble functional nanoparticles via coating with amphiphilic polymer followed by covalent linking with desired biomolecules. Following this approach, carbon nanoparticles are functionalized with polyethylene glycol, primary amine, glucose, arginine, histidine, biotin and folic acid. These functional nanoparticles can be excited with blue/green light (i.e., 400-550 nm) to capture their emission spanning from 550 to 750 nm. Arginine and folic acid functionalized nanoparticles have been demonstrated as fluorescent cell labels where blue and green excitation has been used for imaging of labeled cells. The presented method can be extended for the development of carbon nanoparticle-based other bioimaging probes.

ANTS-anchored Zn-Al-CO{sub 3}-LDH particles as fluorescent probe for sensing of folic acid

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

Liu, Pengfei; Liu, Dan; Liu, Yanhuan

2016-09-15

A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO{sub 3}-layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn{sup 2+} ions of Zn-Al-CO{sub 3}-LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO{sub 3}-LDH particles exhibited highly sensitive and selective response to FA over othermore » common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO{sub 3} groups in ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO{sub 3}-LDH particles can afford a very sensitive system for the sensing FA in aqueous solution. - Highlights: • A novel fluorescent nanosensor has been developed. • The sensor exhibited highly sensitive and selective response to FA. • The fluorescence quenching was fitted to Stern–Volmer equation. • The linear response range was 1–200 μM with a limit of detection of 0.1 μM.« less

Evaluation by fluorescence, STD-NMR, docking and semi-empirical calculations of the o-NBA photo-acid interaction with BSA

NASA Astrophysics Data System (ADS)

Chaves, Otávio A.; Jesus, Catarina S. H.; Cruz, Pedro F.; Sant'Anna, Carlos M. R.; Brito, Rui M. M.; Serpa, Carlos

2016-12-01

Serum albumins present reversible pH dependent conformational transitions. A sudden laser induced pH-jump is a methodology that can provide new insights on localized protein (un)folding processes that occur within the nanosecond to microsecond time scale. To generate the fast pH jump needed to fast-trigger a protein conformational event, a photo-triggered acid generator as o-nitrobenzaldehyde (o-NBA) can be conveniently used. In order to detect potential specific or nonspecific interactions between o-NBA and BSA, we have performed ligand-binding studies using fluorescence spectroscopy, saturation transfer difference (STD) NMR, molecular docking and semi-empirical calculations. Fluorescence quenching indicates the formation of a non-fluorescent complex in the ground-state between the fluorophore and the quencher, but o-NBA does not bind much effectively to the protein (Ka 4.34 × 103 M- 1) and thus can be considered a relatively weak binder. The corresponding thermodynamic parameters: ΔG°, ΔS° and ΔH° showed that the binding process is spontaneous and entropy driven. Results of 1H STD-NMR confirm that the photo-acid and BSA interact, and the relative intensities of the signals in the STD spectra show that all o-NBA protons are equally involved in the binding process, which should correspond to a nonspecific interaction. Molecular docking and semi-empirical calculations suggest that the o-NBA binds preferentially to the Trp-212-containing site of BSA (FA7), interacting via hydrogen bonds with Arg-217 and Tyr-149 residues.

Evaluation by fluorescence, STD-NMR, docking and semi-empirical calculations of the o-NBA photo-acid interaction with BSA.

PubMed

Chaves, Otávio A; Jesus, Catarina S H; Cruz, Pedro F; Sant'Anna, Carlos M R; Brito, Rui M M; Serpa, Carlos

2016-12-05

Serum albumins present reversible pH dependent conformational transitions. A sudden laser induced pH-jump is a methodology that can provide new insights on localized protein (un)folding processes that occur within the nanosecond to microsecond time scale. To generate the fast pH jump needed to fast-trigger a protein conformational event, a photo-triggered acid generator as o-nitrobenzaldehyde (o-NBA) can be conveniently used. In order to detect potential specific or nonspecific interactions between o-NBA and BSA, we have performed ligand-binding studies using fluorescence spectroscopy, saturation transfer difference (STD) NMR, molecular docking and semi-empirical calculations. Fluorescence quenching indicates the formation of a non-fluorescent complex in the ground-state between the fluorophore and the quencher, but o-NBA does not bind much effectively to the protein (Ka~4.34×10(3)M(-1)) and thus can be considered a relatively weak binder. The corresponding thermodynamic parameters: ΔG°, ΔS° and ΔH° showed that the binding process is spontaneous and entropy driven. Results of (1)H STD-NMR confirm that the photo-acid and BSA interact, and the relative intensities of the signals in the STD spectra show that all o-NBA protons are equally involved in the binding process, which should correspond to a nonspecific interaction. Molecular docking and semi-empirical calculations suggest that the o-NBA binds preferentially to the Trp-212-containing site of BSA (FA7), interacting via hydrogen bonds with Arg-217 and Tyr-149 residues. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of an Ultrasonication-Assisted Extraction Based HPLC With a Fluorescence Method for Sensitive Determination of Aflatoxins in Highly Acidic Hibiscus sabdariffa

PubMed Central

Liu, Xiaofei; Ying, Guangyao; Sun, Chaonan; Yang, Meihua; Zhang, Lei; Zhang, Shanshan; Xing, Xiaoyan; Li, Qian; Kong, Weijun

2018-01-01

The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD) after ultrasonication-assisted extraction, immunoaffinity column (IAC) clean-up and on-line post-column photochemical derivatization (PCD). Aflatoxins B1, B2, G1, G2 were extracted from samples by using methanol/water (70:30, v/v) with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0) to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity (R > 0.999), sensitivity (limits of detection (LODs) and limits of quantitation (LOQs) of 0.15–0.65 and 0.53–2.18 μg/kg, respectively), precision (RSD <11%), stability (RSD of 0.2–3.6%), and accuracy (recovery rates of 86.0–102.3%), which all met the stipulated analytical requirements. Analysis of 28 H. sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B1 (AFB1) at 3.11 μg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc. PMID:29681848

Fluorescence detection of esophageal neoplasia

NASA Astrophysics Data System (ADS)

Borisova, E.; Vladimirov, B.; Avramov, L.

2008-06-01

White-light endoscopy is well-established and wide used modality. However, despite the many technological advances that have been occurred, conventional endoscopy is suboptimal and usually detects advanced stage lesions. The limitations of standard endoscopy initiate development of spectroscopic techniques, additional to standard endoscopic equipment. One of the most sensitive approaches is fluorescence spectroscopy of gastrointestinal mucosa for neoplasia detection. In the recent study delta-aminolevulinic acid/Protoporphyrin IX (5-ALA/PpIX) is used as fluorescent marker for dysplasia and tumor detection in esophagus. The 5-ALA is administered per os six hours before measurements at dose 20 mg/kg weight. Excitation source has max of emission at 405 nm and light is delivered by the standard light guide of the endoscopic equipment. Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer. Spectral features observed during endoscopic investigations could be distinct as the next regions: 450-630 nm region, where tissue autofluorescence is observed; 630-710 nm region, where fluorescence of PpIX is clearly pronounced; 530-580 nm region, where minima in the autofluorescence signal are observed, related to reabsorption of blood. The lack of fluorescence peaks in the red spectral area for normal mucosa is an indication for selective accumulation of 5-ALA/PpIX only in abnormal sites Very good correlation between fluorescence signals and histology examination of the lesions investigated is achieved.

Ligand Assisted Stabilization of Fluorescence Nanoparticles; an Insight on the Fluorescence Characteristics, Dispersion Stability and DNA Loading Efficiency of Nanoparticles.

PubMed

Rhouati, Amina; Hayat, Akhtar; Mishra, Rupesh K; Bueno, Diana; Shahid, Shakir Ahmad; Muñoz, Roberto; Marty, Jean Louis

2016-07-01

This work reports on the ligand assisted stabilization of Fluospheres® carboxylate modified nanoparticles (FCMNPs), and subsequently investigation on the DNA loading capacity and fluorescence response of the modified particles. The designed fluorescence bioconjugate was characterized with enhanced fluorescence characteristics, good stability and large surface area with high DNA loading efficiency. For comparison purpose, bovine serum albumin (BSA) and polyethylene glycol (PEG) with three different length strands were used as cross linkers to modify the particles, and their DNA loading capacity and fluorescence characteristics were investigated. By comparing the performance of the particles, we found that the most improved fluorescence characteristics, enhanced DNA loading and high dispersion stability were obtained, when employing PEG of long spacer arm length. The designed fluorescence bioconjugate was observed to maintain all its characteristics under varying pH over an extended period of time. These types of bioconjugates are in great demand for fluorescence imaging and in vivo fluorescence biomedical application, especially when most of the as synthesized fluorescence particles cannot withstand to varying in vivo physiological conditions with decreases in fluorescence response and DNA loading efficiency.

5-Aminolevulinic Acid Induced Fluorescence Is a Powerful Intraoperative Marker for Precise Histopathological Grading of Gliomas with Non-Significant Contrast-Enhancement

PubMed Central

Widhalm, Georg; Kiesel, Barbara; Woehrer, Adelheid; Traub-Weidinger, Tatjana; Preusser, Matthias; Marosi, Christine; Prayer, Daniela; Hainfellner, Johannes A.; Knosp, Engelbert; Wolfsberger, Stefan

2013-01-01

Background Intraoperative identification of anaplastic foci in diffusely infiltrating gliomas (DIG) with non-significant contrast-enhancement on MRI is indispensible to avoid histopathological undergrading and subsequent treatment failure. Recently, we found that 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PpIX) fluorescence can visualize areas with increased proliferative and metabolic activity in such gliomas intraoperatively. As treatment of DIG is predominantely based on histopathological World Health Organisation (WHO) parameters, we analyzed whether PpIX fluorescence can detect anaplastic foci according to these criteria. Methods We prospectively included DIG patients with non-significant contrast-enhancement that received 5-ALA prior to resection. Intraoperatively, multiple samples from PpIX positive and negative intratumoral areas were collected using a modified neurosurgical microscope. In all samples, histopathological WHO criteria and proliferation rate were assessed and correlated to the PpIX fluorescence status. Results A total of 215 tumor specimens were collected in 59 patients. Of 26 WHO grade III gliomas, 23 cases (85%) showed focal PpIX fluorescence, whereas 29 (91%) of 33 WHO grade II gliomas were PpIX negative. In intratumoral areas with focal PpIX fluorescence, mitotic rate, cell density, nuclear pleomorphism, and proliferation rate were significantly higher than in non-fluorescing areas. The positive predictive value of focal PpIX fluorescence for WHO grade III histology was 85%. Conclusions Our study indicates that 5-ALA induced PpIX fluorescence is a powerful marker for intraoperative identification of anaplastic foci according to the histopathological WHO criteria in DIG with non-significant contrast-enhancement. Therefore, application of 5-ALA optimizes tissue sampling for precise histopathological diagnosis independent of brain-shift. PMID:24204718

5-Aminolevulinic acid induced fluorescence is a powerful intraoperative marker for precise histopathological grading of gliomas with non-significant contrast-enhancement.

PubMed

Widhalm, Georg; Kiesel, Barbara; Woehrer, Adelheid; Traub-Weidinger, Tatjana; Preusser, Matthias; Marosi, Christine; Prayer, Daniela; Hainfellner, Johannes A; Knosp, Engelbert; Wolfsberger, Stefan

2013-01-01

Intraoperative identification of anaplastic foci in diffusely infiltrating gliomas (DIG) with non-significant contrast-enhancement on MRI is indispensible to avoid histopathological undergrading and subsequent treatment failure. Recently, we found that 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PpIX) fluorescence can visualize areas with increased proliferative and metabolic activity in such gliomas intraoperatively. As treatment of DIG is predominantely based on histopathological World Health Organisation (WHO) parameters, we analyzed whether PpIX fluorescence can detect anaplastic foci according to these criteria. We prospectively included DIG patients with non-significant contrast-enhancement that received 5-ALA prior to resection. Intraoperatively, multiple samples from PpIX positive and negative intratumoral areas were collected using a modified neurosurgical microscope. In all samples, histopathological WHO criteria and proliferation rate were assessed and correlated to the PpIX fluorescence status. A total of 215 tumor specimens were collected in 59 patients. Of 26 WHO grade III gliomas, 23 cases (85%) showed focal PpIX fluorescence, whereas 29 (91%) of 33 WHO grade II gliomas were PpIX negative. In intratumoral areas with focal PpIX fluorescence, mitotic rate, cell density, nuclear pleomorphism, and proliferation rate were significantly higher than in non-fluorescing areas. The positive predictive value of focal PpIX fluorescence for WHO grade III histology was 85%. Our study indicates that 5-ALA induced PpIX fluorescence is a powerful marker for intraoperative identification of anaplastic foci according to the histopathological WHO criteria in DIG with non-significant contrast-enhancement. Therefore, application of 5-ALA optimizes tissue sampling for precise histopathological diagnosis independent of brain-shift.

Preparation of fluorescently labeled silica nanoparticles using an amino acid-catalyzed seeds regrowth technique: Application to latent fingerprints detection and hemocompatibility studies.

PubMed

Abdelwahab, Walid M; Phillips, Edjohnier; Patonay, Gabor

2018-02-15

The efficiency of an amino acid catalyzed seed regrowth technique (ACSRT) in synthesizing twelve fluorescently labeled core-shell silica nanoparticles (FLSNPs) with tunable sizes, tailored hydrophobicity, low polydispersity as well as high labeling efficiency and minimized dye leakage using different combinations of organosilicate monomers and fluorophores have been systematically investigated in this report. The utilization of some of these FLSNPs in some applications that are facilitated by hydrophobicity such as developing and visualizing latent fingerprints (LFPs) on different surfaces was also investigated. The non-specific binding affinity of the developed nanoparticles to human serum albumin (HSA) and immunoglobulin G (IgG) has also been studied. Fluorescein, fluorescein isothiocyanate and its more hydrophilic butenamine derivative (WA6) have been used in this study. Also, the alkoxysilane precursor, tetraethoxyorthosilicate (TEOS) and its binary mixture with phenyltriethoxysilane (PTEOS) or 3-aminopropyl triethoxysilane (APTES) have been used in preparing the FLSNPs with tailored compositions for the core and shell of the nanoparticles. The mean diameters of the PTEOS-coated FLSNPs were between 33.4±5.9 and 42.2±10.8 nm as shown by the SEM measurements. The obtained results highlight the advantages of having a hydrophobic surface along with proper selection of the monomers forming the core to match the properties of the fluorescent reporters for clear detection of LFPs even using dyes of low hydrophobicity such as fluorescein and WA6. Furthermore, some of the developed FLSNPs were compared with bare silica nanoparticles in terms of nonspecific protein adsorption and hemolysis. The obtained results proved that the selected FLSNPs had a superior hemocompatibility in comparison with bare silica nanoparticles. These FLSNPs could also be used in some bio-related and diagnostic applications such as immunoassays and cell imaging purposes. Copyright © 2017

Determination of Cancer Cell-Based pH-Sensitive Fluorescent Carbon Nanoparticles of Cross-Linked Polydopamine by Fluorescence Sensing of Alkaline Phosphatase Activity on Coated Surfaces and Aqueous Solution.

PubMed

Kang, Eun Bi; Choi, Cheong A; Mazrad, Zihnil Adha Islamy; Kim, Sung Han; In, Insik; Park, Sung Young

2017-12-19

The tumor-specific sensitive fluorescence sensing of cellular alkaline phosphatase (ALP) activity on the basis of host-guest specific and pH sensitivity was conducted on coated surfaces and aqueous states. Cross-linked fluorescent nanoparticles (C-FNP) consisting of β-cyclodextrin (β-CD)/boronic acid (BA) and fluorescent hyaluronic acid [FNP(HA)] were conjugated to fluorescent polydopamine [FNP(pDA)]. To determine the quenching effect of this system, hydrolysis of 4-nitrophenyl phosphate (NPP) to 4-nitrophenol (NP) was performed in the cavity of β-CD in the presence of ALP activated photoinduced electron transfer (PET) between NP and C-FNP. At an ALP level of 30-1000 U/L, NP caused off-emission of C-FNP because of their specific host-guest recognition. Fluorescence can be recovered under pH shock due to cleavage of the diol bond between β-CD and BA, resulting in release of NP from the fluorescent system. Sensitivity of the assays was assessed by confocal imaging not only in aqueous states, but also for the first time on coated surfaces in MDAMB-231 and MDCK cells. This novel system demonstrated high sensitivity to ALP through generation of good electron donor/acceptor pair during the PET process. Therefore, this fluorescence sensor system can be used to enhance ALP monitoring and cancer diagnosis on both coated surfaces and in aqueous states in clinical settings.

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

Improved Charge-Transfer Fluorescent Dyes

NASA Technical Reports Server (NTRS)

Meador, Michael

2005-01-01

Improved charge-transfer fluorescent dyes have been developed for use as molecular probes. These dyes are based on benzofuran nuclei with attached phenyl groups substituted with, variously, electron donors, electron acceptors, or combinations of donors and acceptors. Optionally, these dyes could be incorporated as parts of polymer backbones or as pendant groups or attached to certain surfaces via self-assembly-based methods. These dyes exhibit high fluorescence quantum yields -- ranging from 0.2 to 0.98, depending upon solvents and chemical structures. The wavelengths, quantum yields, intensities, and lifetimes of the fluorescence emitted by these dyes vary with (and, hence, can be used as indicators of) the polarities of solvents in which they are dissolved: In solvents of increasing polarity, fluorescence spectra shift to longer wavelengths, fluorescence quantum yields decrease, and fluorescence lifetimes increase. The wavelengths, quantum yields, intensities, and lifetimes are also expected to be sensitive to viscosities and/or glass-transition temperatures. Some chemical species -- especially amines, amino acids, and metal ions -- quench the fluorescence of these dyes, with consequent reductions in intensities, quantum yields, and lifetimes. As a result, the dyes can be used to detect these species. Another useful characteristic of these dyes is a capability for both two-photon and one-photon absorption. Typically, these dyes absorb single photons in the ultraviolet region of the spectrum (wavelengths < 400 nm) and emit photons in the long-wavelength ultraviolet, visible, and, when dissolved in some solvents, near-infrared regions. In addition, these dyes can be excited by two-photon absorption at near-infrared wavelengths (600 to 800 nm) to produce fluorescence spectra identical to those obtained in response to excitation by single photons at half the corresponding wavelengths (300 to 400 nm). While many prior fluorescent dyes exhibit high quantum yields

An Environmentally Sensitive Fluorescent Dye as a Multidimensional Probe of Amyloid Formation

PubMed Central

2016-01-01

We have explored amyloid formation using poly(amino acid) model systems in which differences in peptide secondary structure and hydrophobicity can be introduced in a controlled manner. We show that an environmentally sensitive fluorescent dye, dapoxyl, is able to identify β-sheet structure and hydrophobic surfaces, structural features likely to be related to toxicity, as a result of changes in its excitation and emission profiles and its relative quantum yield. These results show that dapoxyl is a multidimensional probe of the time dependence of amyloid aggregation, which provides information about the presence and nature of metastable aggregation intermediates that is inaccessible to the conventional probes that rely on changes in quantum yield alone. PMID:26865546

Charge-Transfer-Induced Fluorescence Quenching of Anthracene Derivatives and Selective Detection of Picric Acid.

PubMed

Santra, Dines Chandra; Bera, Manas Kumar; Sukul, Pradip Kumar; Malik, Sudip

2016-02-01

2,6-Divinylpyridine-appended anthracene derivatives flanked by two alkyl chains at the 9,10-position of the core have been designed, synthesized, and characterized by NMR, MALDI-TOF, FTIR, and single-crystal XRD. These anthracene derivatives are able to recognize picric acid (2,4,6-trinitrophenol, PA) selectively down to parts per billion (ppb) level in aqueous as well as nonaqueous medium. Fluorescence emission of these derivatives in solution is significantly quenched by adding trace amounts of PA, even in the presence of other competing analogues, such as 2,4-dinitrophenol (2,4-DNP), 4-nitrophenol (NP), nitrobenzene (NB), benzoic acid (BA), and phenol (PH). The high sensitivity of these derivatives toward PA is considered as a combined effect of the proton-induced intramolecular charge transfer (ICT) as well as electron transfer from the electron-rich anthracene to the electron-deficient PA. Moreover, visual detection of PA has been successfully demonstrated in the solid state by using different substrates. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Paper-based solid-phase nucleic acid hybridization assay using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Noor, M Omair; Shahmuradyan, Anna; Krull, Ulrich J

2013-02-05

A paper-based solid-phase assay is presented for transduction of nucleic acid hybridization using immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). The surface of paper was modified with imidazole groups to immobilize QD-probe oligonucleotide conjugates that were assembled in solution. Green-emitting QDs (gQDs) were FRET-paired with Cy3 acceptor. Hybridization of Cy3-labeled oligonucleotide targets provided the proximity required for FRET-sensitized emission from Cy3, which served as an analytical signal. The assay exhibited rapid transduction of nucleic acid hybridization within minutes. Without any amplification steps, the limit of detection of the assay was found to be 300 fmol with the upper limit of the dynamic range at 5 pmol. The implementation of glutathione-coated QDs for the development of nucleic acid hybridization assay integrated on a paper-based platform exhibited excellent resistance to nonspecific adsorption of oligonucleotides and showed no reduction in the performance of the assay in the presence of large quantities of noncomplementary DNA. The selectivity of nucleic acid hybridization was demonstrated by single-nucleotide polymorphism (SNP) detection at a contrast ratio of 19 to 1. The reuse of paper over multiple cycles of hybridization and dehybridization was possible, with less than 20% reduction in the performance of the assay in five cycles. This work provides an important framework for the development of paper-based solid-phase QD-FRET nucleic acid hybridization assays that make use of a ratiometric approach for detection and analysis.

Fluorescence spectroscopy of gastrointestinal tumors using δ-ALA

NASA Astrophysics Data System (ADS)

Borisova, E. G.; Vladimirov, B. G.; Angelov, I. G.; Avramov, L. A.

2007-03-01

In the recent study delta-aminolevulinic acid/Protoporphyrin IX (δ-ALA/PpIX) is used as fluorescent marker for dysplasia and tumor detection in esophagus and stomach. The δ-ALA is administered per os six hours before measurements at dose 20mg/kg weight. High-power light-emitting diode at 405 nm is used as an excitation source. Special opto-mechanical device is built to use the light guide of standard video-endoscopic system (Olimpus Corp.). Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer (USB4000, OceanOptics Inc.). The fluorescence detected from tumor sites has very complex spectral origins. It consists of autofluorescence, fluorescence from exogenous fluorophores and re-absorption from the chromophores accumulated in the tissue investigated. Mucosa autofluorescence lies at 450-600 nm region. The fluorescence of PpIX is clearly pronounced at the 630-710 nm region. Deep minima in the tumor fluorescence signals are observed in the region 540-575 nm, related to hemoglobin re-absorption. Such high hemoglobin content is an indication of the tumors neovascularisation and it is clearly pronounced in all dysplastic and tumor sites investigated. The lack of fluorescence peaks in the red spectral area for normal mucosa is an indication for selective accumulation of δ-ALA/PpIX only in abnormal sites and gives high contrast when lesion borders are determined from clinicians during video observation in the process of diagnostic procedure. Very good correlation between fluorescence signals and histology examination results of the lesions investigated is achieved.

Directed evolution of an extremely stable fluorescent protein.

PubMed

Kiss, Csaba; Temirov, Jamshid; Chasteen, Leslie; Waldo, Geoffrey S; Bradbury, Andrew R M

2009-05-01

In this paper we describe the evolution of eCGP123, an extremely stable green fluorescent protein based on a previously described fluorescent protein created by consensus engineering (CGP: consensus green protein). eCGP123 could not be denatured by a standard thermal melt, preserved almost full fluorescence after overnight incubation at 80 degrees C and possessed a free energy of denaturation of 12.4 kcal/mol. It was created from CGP by a recursive process involving the sequential introduction of three destabilizing heterologous inserts, evolution to overcome the destabilization and finally 'removal' of the destabilizing insert by gene synthesis. We believe that this approach may be generally applicable to the stabilization of other proteins.

Protein amyloids develop an intrinsic fluorescence signature during aggregation†

PubMed Central

Chan, Fiona T. S.; Kaminski Schierle, Gabriele S.; Kumita, Janet R.; Bertoncini, Carlos W.; Dobson, Christopher M.; Kaminski, Clemens F.

2017-01-01

We report observations of an intrinsic fluorescence in the visible range, which develops during the aggregation of a range of polypeptides, including the disease-related human peptides amyloid-β(1–40) and (1–42), lysozyme and tau. Characteristic fluorescence properties such as the emission lifetime and spectra were determined experimentally. This intrinsic fluorescence is independent of the presence of aromatic side-chain residues within the polypeptide structure. Rather, it appears to result from electronic levels that become available when the polypeptide chain folds into a cross-β sheet scaffold similar to what has been reported to take place in crystals. We use these findings to quantify protein aggregation in vitro by fluorescence imaging in a label-free manner. PMID:23420088

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

In vivo quantitative visualization of hypochlorous acid in the liver using a novel selective two-photon fluorescent probe

NASA Astrophysics Data System (ADS)

Wang, Haolu; Jayachandran, Aparna; Gravot, Germain; Liang, Xiaowen; Thorling, Camilla A.; Zhang, Run; Liu, Xin; Roberts, Michael S.

2016-11-01

Hypochlorous acid (HOCl) plays a vital role in physiological events and diseases. During hepatic ischemia-reperfusion (I/R) injury, HOCl is generated by neutrophils and diffuses into hepatocytes, causing oxidant stress-mediated injury. Although many probes have been developed to detect HOCl, most were difficult to be distinguished from endogenous fluorophores in intravital imaging and only can be employed under one-photon microscopy. A novel iridium(III) complex-based ferrocene dual-signaling chemosensor (Ir-Fc) was designed and synthesized. Ir-Fc exhibited a strong positive fluorescent response only in the presence of HOCl, whereas negligible fluorescent signals were observed upon the additions of other reactive oxygen/nitrogen species and metal ions. There was a good linear relationship between probe responsive fluorescent intensity and HOCl concentration. Ir-Fc was then intravenously injected into BALB/c mice at the final concentration of 50 μM and the mouse livers were imaged using multiphoton microscopy (MPM). In the I/R liver, reduced autofluorescence was detected by MPM, indicating the hepatocyte necrosis. Remarkable enhancement of red fluorescence was observed in hepatocytes with decreased autofluorescence, indicating the reaction of Ir-Fc with endogenous HOCl molecules. The cellular concentration of HOCl was first calculated based on the intensity of MPM images. No obvious toxic effects were observed in histological examination of major organs after Ir-Fc injection. In summary, Ir-Fc has low cytotoxicity, high specificity to HOCl, and rapid "off-on" fluorescence. It is suitable for dynamic quantitatively monitoring HOCl generation using MPM at the cellular level. This technique can be readily extended to examination of liver diseases and injury.

PtII6 nanoscopic cages with an organometallic backbone as sensors for picric acid.

PubMed

Samanta, Dipak; Mukherjee, Partha Sarathi

2013-12-28

An organometallic building block 1,3,5-tris(4-trans-Pt(PEt3)2I(ethynyl)phenyl)benzene (1) incorporating Pt-ethynyl functionality has been synthesized and characterized. [2 + 3] self-assembly of its nitrate analogue 1,3,5-tris(4-trans-Pt(PEt3)2(ONO2)(ethynyl)phenyl)benzene (2) with "clip" type bidentate donors (L1-L3) separately afforded three trigonal prismatic architectures (3a-3c), respectively. All these prisms were characterized and their shapes/sizes are predicted through geometry optimization employing molecular mechanics universal force field (MMUFF) simulation. The extended π-conjugation including the presence of Pt-ethynyl functionality makes them electron rich as well as luminescent in nature. Macrocycles 3b and 3c exhibit fluorescence quenching in solution upon addition of picric acid [PA], which is a common constituent of many explosives. Interestingly, the non-responsive nature of fluorescent intensity towards other electron-deficient nitro-aromatic explosives (NAEs) makes them promising selective sensors for PA with a detection limit predicted to be ppb level. Furthermore, solid-state quenching of fluorescent intensity of the thin film of 3b upon exposure to saturated vapor of picric acid has drawn special attention for infield applications.

Identification of antisense nucleic acid hybridization sites in mRNA molecules with self-quenching fluorescent reporter molecules

PubMed Central

Gifford, Lida K.; Opalinska, Joanna B.; Jordan, David; Pattanayak, Vikram; Greenham, Paul; Kalota, Anna; Robbins, Michelle; Vernovsky, Kathy; Rodriguez, Lesbeth C.; Do, Bao T.; Lu, Ponzy; Gewirtz, Alan M.

2005-01-01

We describe a physical mRNA mapping strategy employing fluorescent self-quenching reporter molecules (SQRMs) that facilitates the identification of mRNA sequence accessible for hybridization with antisense nucleic acids in vitro and in vivo, real time. SQRMs are 20–30 base oligodeoxynucleotides with 5–6 bp complementary ends to which a 5′ fluorophore and 3′ quenching group are attached. Alone, the SQRM complementary ends form a stem that holds the fluorophore and quencher in contact. When the SQRM forms base pairs with its target, the structure separates the fluorophore from the quencher. This event can be reported by fluorescence emission when the fluorophore is excited. The stem–loop of the SQRM suggests that SQRM be made to target natural stem–loop structures formed during mRNA synthesis. The general utility of this method is demonstrated by SQRM identification of targetable sequence within c-myb and bcl-6 mRNA. Corresponding antisense oligonucleotides reduce these gene products in cells. PMID:15718294

Determination of cortisol in human plasma by thin-layer chromatography and fluorescence derivatization with isonicotinic acid hydrazide.

PubMed

Fenske, Martin

2008-01-01

The present work describes a specific and rapid determination of cortisol in human plasma. The method includes liquid-liquid extraction of plasma samples, thin-layer chromatography (TLC) of ethanolic extracts on aluminium foil-backed silica gel 60 TLC plates, derivatization of cortisol with isonicotinic acid hydrazide, and densitometric measurement of the fluorescence intensity of cortisol hydrazone. The fluorescence was linearly related to cortisol amounts; the correlation coefficients of standard curve plots were r>0.99. The coefficient of variation ranged between 2.8-7.9% (20 ng, within-assay/between assay variation) and 1.6-6.8% (80 ng, within-assay/between assay variation). The recovery of cortisol from plasma spiked with 21-deoxycortisol was 85%+/-4%. Cortisol concentration in the plasma was 66+/-32 ng/mL (mean+/-standard deviation, n=24). The advantage of this method is its simplicity to separate cortisol from other steroids by TLC, its specificity (formation of cortisol hydrazone), and the rapid quantitation of cortisol by densitometry.

Nucleic acid encoding a self-assembling split-fluorescent protein system

DOEpatents

Waldo, Geoffrey S.; Cabantous, Stephanie

2014-04-01

The invention provides a protein labeling and detection system based on self-complementing fragments of fluorescent and chromophoric proteins. The system of the invention is exemplified with various combinations of self-complementing fragments derived from Aequorea victoria Green Fluorescent Protein (GFP), which are used to detect and quantify protein solubility in multiple assay formats, both in vitro and in vivo.

Nucleic acid encoding a self-assembling split-fluorescent protein system

DOEpatents

Waldo, Geoffrey S [Santa Fe, NM; Cabantous, Stephanie [Los Alamos, NM

2011-06-07

The invention provides a protein labeling and detection system based on self-complementing fragments of fluorescent and chromophoric proteins. The system of the invention is exemplified with various combinations of self-complementing fragments derived from Aequorea victoria Green Fluorescent Protein (GFP), which are used to detect and quantify protein solubility in multiple assay formats, both in vitro and in vivo.

Nucleic acid encoding a self-assembling split-fluorescent protein system

DOEpatents

Waldo, Geoffrey S.; Cabantous, Stephanie

2015-07-14

The invention provides a protein labeling and detection system based on self-complementing fragments of fluorescent and chromophoric proteins. The system of the invention is exemplified with various combinations of self-complementing fragments derived from Aequorea victoria Green Fluorescent Protein (GFP), which are used to detect and quantify protein solubility in multiple assay formats, both in vitro and in vivo.

Fluorescent biosensor for the detection of hyaluronidase: intensity-based ratiometric sensing and fluorescence lifetime-based sensing using a long lifetime azadioxatriangulenium (ADOTA) fluorophore.

PubMed

Chib, Rahul; Mummert, Mark; Bora, Ilkay; Laursen, Bo W; Shah, Sunil; Pendry, Robert; Gryczynski, Ignacy; Borejdo, Julian; Gryczynski, Zygmunt; Fudala, Rafal

2016-05-01

In this report, we have designed a rapid and sensitive, intensity-based ratiometric sensing as well as lifetime-based sensing probe for the detection of hyaluronidase activity. Hyaluronidase expression is known to be upregulated in various pathological conditions. We have developed a fluorescent probe by heavy labeling of hyaluronic acid with a new orange/red-emitting organic azadioxatriangulenium (ADOTA) fluorophore, which exhibits a long fluorescence lifetime (∼20 ns). The ADOTA fluorophore in water has a peak fluorescence lifetime of ∼20 ns and emission spectra centered at 560 nm. The heavily ADOTA-labeled hyaluronic acid (HA-ADOTA) shows a red shift in the peak emission wavelength (605 nm), a weak fluorescence signal, and a shorter fluorescence lifetime (∼4 ns) due to efficient self-quenching and formation of aggregates. In the presence of hyaluronidase, the brightness and fluorescence lifetime of the sample increase with a blue shift in the peak emission to its original wavelength at 560 nm. The ratio of the fluorescence intensity of the HA-ADOTA probe at 560 and 605 nm can be used as the sensing method for the detection of hyaluronidase. The cleavage of the hyaluronic acid macromolecule reduces the energy migration between ADOTA molecules, as well as the degree of self-quenching and aggregation. This probe can be efficiently used for both intensity-based ratiometric sensing as well as fluorescence lifetime-based sensing of hyaluronidase. The proposed method makes it a rapid and sensitive assay, useful for analyzing levels of hyaluronidase in relevant clinical samples like urine or plasma. Graphical Abstract Scheme showing cleavage of HA-ADOTA probe by hyaluronidase and the change in the emission spectrum of HA-ADOTA probe before and after cleavage by hyaluronidase.

Influence of different forms of acidities on soil microbiological properties and enzyme activities at an acid mine drainage contaminated site.

PubMed

Sahoo, Prafulla Kumar; Bhattacharyya, Pradip; Tripathy, Subhasish; Equeenuddin, Sk Md; Panigrahi, M K

2010-07-15

Assessment of microbial parameters, viz. microbial biomass, fluorescence diacetate, microbial respiration, acid phosphatase, beta-glucosidase and urease with respect to acidity helps in evaluating the quality of soils. This study was conducted to investigate the effects of different forms of acidities on soil microbial parameters in an acid mine drainage contaminated site around coal deposits in Jainta Hills of India. Total potential and exchangeable acidity, extractable and exchangeable aluminium were significantly higher in contaminated soil compared to the baseline (p<0.01). Different forms of acidity were significantly and positively correlated with each other (p<0.05). Further, all microbial properties were positively and significantly correlated with organic carbon and clay (p<0.05). The ratios of microbial parameters with organic carbon were negatively correlated with different forms of acidity. Principal component analysis and cluster analyses showed that the microbial activities are not directly influenced by the total potential acidity and extractable aluminium. Though acid mine drainage affected soils had higher microbial biomass and activities due to higher organic matter content than those of the baseline soils, the ratios of microbial parameters/organic carbon indicated suppression of microbial growth and activities due to acidity stress. 2010 Elsevier B.V. All rights reserved.

Simultaneous determination of acetylsalicylic acid and salicylic acid in human plasma by isocratic high-pressure liquid chromatography with post-column hydrolysis and fluorescence detection.

PubMed

Hobl, Eva-Luise; Jilma, Bernd; Ebner, Josef; Schmid, Rainer W

2013-06-01

A selective, sensitive and rapid high-performance liquid chromatography method with post-column hydrolysis and fluorescence detection was developed for the simultaneous quantification of acetylsalicylic acid and its metabolite salicylic acid in human plasma. Following the addition of 2-hydroxy-3-methoxybenzoic acid as internal standard and simple protein precipitation with acetonitrile, the analytes were separated on a ProntoSIL 120 C18 ace-EPS column (150 × 2 mm, 3 µm) protected by a C8 guard column (5 µm). The mobile phase, 10 mm formic acid in water (pH 2.9) and acetonitrile (70:30, v/v), was used at a flow rate of 0.35 mL/min. After on-line post-column hydrolysis of acetylsalicylic acid (ASA) to salicylic acid (SA) by addition of alkaline solution, the analytes were measured at 290 nm (λex ) and 400 nm (λem ). The method was linear in the concentration ranges between 0.05 and 20 ng/μL for both ASA and SA with a lower limit of quantification of 25 pg/μL for SA and 50 pg/μL for ASA. The limit of detection was 15 pg/μL for SA and 32.5 pg/μL for ASA. The analysis of ASA and SA can be carried out within 8 min; therefore this method is suitable for measuring plasma concentrations of salicylates in clinical routine. Copyright © 2012 John Wiley & Sons, Ltd.

Fluorescence enhancement of quercetin complexes by silver nanoparticles and its analytical application

NASA Astrophysics Data System (ADS)

Liu, Ping; Zhao, Liangliang; Wu, Xia; Huang, Fei; Wang, Minqin; Liu, Xiaodan

2014-03-01

It is found that the plasmon effect of silver nanoparticles (AgNPs) helps to enhance the fluorescence intensity of the quercetin (Qu) and nucleic acids system. Qu exhibited strong fluorescence enhancement when it bound to nucleic acids in the presence of AgNPs. Based on this, a sensitive method for the determination of nucleic acids was developed. The detection limits for the nucleic acids (S/N = 3) were reduced to the ng mL-1 level. The interaction mechanism of the AgNPs-fish sperm DNA (fsDNA)-Qu system was also investigated in this paper. This complex system of Qu and AgNPs was also successfully used for the detection of nucleic acids in agarose gel electrophoresis analysis. Preliminary results indicated that AgNPs also helped to improve sensitivity in the fluorescence image analysis of Qu combined with cellular contents in Arabidopsis thaliana protoplasts.

An overview of remote sensing of chlorophyll fluorescence

NASA Astrophysics Data System (ADS)

Xing, Xiao-Gang; Zhao, Dong-Zhi; Liu, Yu-Guang; Yang, Jian-Hong; Xiu, Peng; Wang, Lin

2007-03-01

Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyl l - a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.

Latest results of 5-ALA-based fluorescence diagnosis and other medical disciplines

NASA Astrophysics Data System (ADS)

Baumgartner, Reinhold

1999-02-01

Preclinical and clinical studies on 5-aminolevulinic acid (5- ALA) induced Protoporphyrin IX (PPIX) are performed in various departments now following promising clinical results for the detection of bladder cancer in urology. This paper provides an overview on the progress of 5-ALA assisted fluorescence diagnosis in urology, pulmonology, neurosurgery, gynecology and ENT coordinated by the Laser Research Laboratory of the Ludwig-Maximilians-University in Munich. 5-ALA can be applied either topically or systematically to induce an intracellular accumulation of fluorescing PPIX. With appropriate dosage of 5-ALA, malignant tissue can be stained selectively, and irradiation with violet light excites a bright red fluorescence of the tumor visible with naked eyes. Optical properties of the tissue tend to hamper the precise identification and demarcation of suspect areas in fluorescence images. Multicolor remission and fluorescence imaging, therefore, should improve tumor localization in future.

Fluorescence dye tagging scheme for mercury quantification and speciation

DOEpatents

Jiao, Hong; Catterall, Hannah

2015-09-22

A fluorescent dye or fluorophore capable of forming complexes with mercury comprises 6,8-difluoro-7-hydroxy-2-oxo-2H-chromene-3-carboxylate amide, wherein the amide is formed by reacting the succinimidyl ester (Pacific Blue.TM.) with an amino acid containing a thiol group, such as cysteine or glutathione. Mercury complexes of the fluorophore fluoresce when excited by a UV or violet laser diode, and the detected intensity can be calibrated to quantify the concentration of mercury in a sample reacted with the fluorophore.

A synthesis of fluorescent starch based on carbon nanoparticles for fingerprints detection

NASA Astrophysics Data System (ADS)

Li, Hongren; Guo, Xingjia; Liu, Jun; Li, Feng

2016-10-01

A pyrolysis method for synthesizing carbon nanoparticles (CNPs) were developed by using malic acid and ammonium oxalate as raw materials. The incorporation of a minor amount of carbon nanoparticles into starch powder imparts remarkable color-tunability. Based on this phenomenon, an environment friendly fluorescent starch powder for detecting latent fingerprints in non-porous surfaces was prepared. The fingerprints on different non-porous surfaces developed with this powder showed very good fluorescent images under ultraviolet excitation. The method using fluorescent starch powder as fluorescent marks is simple, rapid and green. Experimental results illustrated the effectiveness of proposed methods, enabling its practical applications in forensic sciences.

Metal ion influence on eumelanin fluorescence and structure.

PubMed

Sutter, Jens-Uwe; Birch, David J S

2014-04-10

Melanin has long been thought to have an unworkably weak and complex fluorescence, but here we study its intrinsic fluorescence in order to demonstrate how metal ions can be used to control the rate of formation, constituents and structure of eumelanin formed from the well-known laboratory auto-oxidation of 3,4-dihydroxy-L-phenylalanine (L-DOPA). The effect on eumelanin absorption and fluorescence of a range of solvated metal ions is reported including Cu, Zn, Ni, Na and K. Monovalent cations and Zn have little effect, but the effect of transition metal cations can be considerable. For example, at pH 10, copper ions are shown to accelerate the onset of eumelanin formation, but not the rate of formation once it commences, and simplify the usual complex structure and intrinsic fluorescence of eumelanin in a way that is consistent with an increased abundance of 5,5-dihydroxyindole-2-carboxylic acid (DHICA). The presence of a dominant 6 ns fluorescence decay time at 480 nm, when excited at 450 nm describes a distinct photophysical species, which we tentatively assign to small oligomers. Copper is well-known to normally quench fluorescence, but increasing amounts of copper surprisingly leads to an increase in the fluorescence decay time of eumelanin, while reducing the fluorescence intensity, suggesting copper modification of the excited state. Such results have bearing on diverse areas. The most accepted morphology for melanin is that of a graphite-like sheet structure, and one which readily binds metal ions, an interaction that is thought to have an important, though as yet unclear bearing on several areas of medicine including neurology. There is also increasing interest in bio-mimicry by preparing and labelling sheet structures with metal ions for new electronic and photonic materials.

Metal ion influence on eumelanin fluorescence and structure

NASA Astrophysics Data System (ADS)

Sutter, Jens-Uwe; Birch, David J. S.

2014-06-01

Melanin has long been thought to have an unworkably weak and complex fluorescence, but here we study its intrinsic fluorescence in order to demonstrate how metal ions can be used to control the rate of formation, constituents and structure of eumelanin formed from the well-known laboratory auto-oxidation of 3,4-dihydroxy-L-phenylalanine (L-DOPA). The effect on eumelanin absorption and fluorescence of a range of solvated metal ions is reported including Cu, Zn, Ni, Na and K. Monovalent cations and Zn have little effect, but the effect of transition metal cations can be considerable. For example, at pH 10, copper ions are shown to accelerate the onset of eumelanin formation, but not the rate of formation once it commences, and simplify the usual complex structure and intrinsic fluorescence of eumelanin in a way that is consistent with an increased abundance of 5,5-dihydroxyindole-2-carboxylic acid (DHICA). The presence of a dominant 6 ns fluorescence decay time at 480 nm, when excited at 450 nm describes a distinct photophysical species, which we tentatively assign to small oligomers. Copper is well-known to normally quench fluorescence, but increasing amounts of copper surprisingly leads to an increase in the fluorescence decay time of eumelanin, while reducing the fluorescence intensity, suggesting copper modification of the excited state. Such results have bearing on diverse areas. The most accepted morphology for melanin is that of a graphite-like sheet structure, and one which readily binds metal ions, an interaction that is thought to have an important, though as yet unclear bearing on several areas of medicine including neurology. There is also increasing interest in bio-mimicry by preparing and labelling sheet structures with metal ions for new electronic and photonic materials.

Establishing and validating the fluorescent amyloid ligand h-FTAA (heptamer formyl thiophene acetic acid) to identify transthyretin amyloid deposits in carpal tunnel syndrome.

PubMed

Hahn, Katharina; Nilsson, K Peter R; Hammarström, Per; Urban, Peter; Meliss, Rolf Rüdiger; Behrens, Hans-Michael; Krüger, Sandra; Röcken, Christoph

2017-06-01

Transthyretin-derived (ATTR) amyloidosis is a frequent finding in carpal tunnel syndrome. We tested the following hypotheses: the novel fluorescent amyloid ligand heptameric formic thiophene acetic acid (h-FTAA) has a superior sensitivity for the detection of amyloid compared with Congo red-staining; Amyloid load correlates with patient gender and/or patient age. We retrieved 208 resection specimens obtained from 184 patients with ATTR amyloid in the carpal tunnel. Serial sections were stained with Congo red, h-FTAA and an antibody directed against transthyretin (TTR). Stained sections were digitalized and forwarded to computational analyses. The amount of amyloid was correlated with patient demographics. Amyloid stained intensely with h-FTAA and an anti-TTR-antibody. Congo red-staining combined with fluorescence microscopy was significantly less sensitive than h-FTAA-fluorescence and TTR-immunostaining: the highest percentage area was found in TTR-immunostained sections, followed by h-FTAA and Congo red. The Pearson correlation coefficient was .8 (Congo red vs. h-FTAA) and .9 (TTR vs. h-FTAA). Amyloid load correlated with patient gender, anatomical site and patient age. h-FTAA is a highly sensitive method to detect even small amounts of ATTR amyloid in the carpal tunnel. The staining protocol is easy and h-FTAA may be a much more sensitive procedure to detect amyloid at an earlier stage.

Expression of gamma-aminobutyric acid rho 1 and rho 1 Delta 450 as gene fusions with the green fluorescent protein.

PubMed

Martinez-Torres, A; Miledi, R

2001-02-13

The functional characteristics and cellular localization of the gamma aminobutyric acid (GABA) rho 1 receptor and its nonfunctional isoform rho 1 Delta 450 were investigated by expressing them as gene fusions with the enhanced version of the green fluorescent protein (GFP). Oocytes injected with rho 1-GFP had receptors that gated chloride channels when activated by GABA. The functional characteristics of these receptors were the same as for those of wild-type rho 1 receptors. Fluorescence, because of the chimeric receptors expressed, was over the whole oocyte but was more intense near the cell surface and more abundant in the animal hemisphere. Similar to the wild type, rho 1 Delta 450-GFP did not lead to the expression of functional GABA receptors, and injected oocytes failed to generate currents even after exposure to high concentrations of GABA. Nonetheless, the fluorescence displayed by oocytes expressing rho 1 Delta 450-GFP was distributed similarly to that of rho 1-GFP. Mammalian cells transfected with the rho 1-GFP or rho 1 Delta 450-GFP constructs showed mostly intracellularly distributed fluorescence in confocal microscope images. A sparse localization of fluorescence was observed in the plasma membrane regardless of the cell line used. We conclude that rho 1 Delta 450 is expressed and transported close to, and perhaps incorporated into, the plasma membrane. Thus, rho 1- and rho 1 Delta 450-GFP fusions provide a powerful tool to visualize the traffic of GABA type C receptors.

Expression of γ-aminobutyric acid ρ1 and ρ1Δ450 as gene fusions with the green fluorescent protein

PubMed Central

Martínez-Torres, Ataúlfo; Miledi, Ricardo

2001-01-01

The functional characteristics and cellular localization of the γaminobutyric acid (GABA) ρ1 receptor and its nonfunctional isoform ρ1Δ450 were investigated by expressing them as gene fusions with the enhanced version of the green fluorescent protein (GFP). Oocytes injected with ρ1-GFP had receptors that gated chloride channels when activated by GABA. The functional characteristics of these receptors were the same as for those of wild-type ρ1 receptors. Fluorescence, because of the chimeric receptors expressed, was over the whole oocyte but was more intense near the cell surface and more abundant in the animal hemisphere. Similar to the wild type, ρ1Δ450-GFP did not lead to the expression of functional GABA receptors, and injected oocytes failed to generate currents even after exposure to high concentrations of GABA. Nonetheless, the fluorescence displayed by oocytes expressing ρ1Δ450-GFP was distributed similarly to that of ρ1-GFP. Mammalian cells transfected with the ρ1-GFP or ρ1Δ450-GFP constructs showed mostly intracellularly distributed fluorescence in confocal microscope images. A sparse localization of fluorescence was observed in the plasma membrane regardless of the cell line used. We conclude that ρ1Δ450 is expressed and transported close to, and perhaps incorporated into, the plasma membrane. Thus, ρ1- and ρ1Δ450-GFP fusions provide a powerful tool to visualize the traffic of GABA type C receptors. PMID:11172056

Color transitions in coral's fluorescent proteins by site-directed mutagenesis

PubMed Central

Gurskaya, Nadya G; Savitsky, Alexander P; Yanushevich, Yurii G; Lukyanov, Sergey A; Lukyanov, Konstantin A

2001-01-01

Background Green Fluorescent Protein (GFP) cloned from jellyfish Aequorea victoria and its homologs from corals Anthozoa have a great practical significance as in vivo markers of gene expression. Also, they are an interesting puzzle of protein science due to an unusual mechanism of chromophore formation and diversity of fluorescent colors. Fluorescent proteins can be subdivided into cyan (~ 485 nm), green (~ 505 nm), yellow (~ 540 nm), and red (>580 nm) emitters. Results Here we applied site-directed mutagenesis in order to investigate the structural background of color variety and possibility of shifting between different types of fluorescence. First, a blue-shifted mutant of cyan amFP486 was generated. Second, it was established that cyan and green emitters can be modified so as to produce an intermediate spectrum of fluorescence. Third, the relationship between green and yellow fluorescence was inspected on closely homologous green zFP506 and yellow zFP538 proteins. The following transitions of colors were performed: yellow to green; yellow to dual color (green and yellow); and green to yellow. Fourth, we generated a mutant of cyan emitter dsFP483 that demonstrated dual color (cyan and red) fluorescence. Conclusions Several amino acid substitutions were found to strongly affect fluorescence maxima. Some positions primarily found by sequence comparison were proved to be crucial for fluorescence of particular color. These results are the first step towards predicting the color of natural GFP-like proteins corresponding to newly identified cDNAs from corals. PMID:11459517

pH-controlled silicon nanowires fluorescence switch

NASA Astrophysics Data System (ADS)

Mu, Lixuan; Shi, Wensheng; Zhang, Taiping; Zhang, Hongyan; She, Guangwei

2010-08-01

Covalently immobilizing photoinduced electronic transfer (PET) fluorophore 3-[N, N-bis(9-anthrylmethyl)amino]-propyltriethoxysilane (DiAN) on the surface of silicon nanowires (SiNWs) resulted a SiNWs-based fluorescence switch. This fluorescence switch is operated by adjustment of the acidity of the environment and exhibits sensitive response to pH at the range from 8 to 10. Such response is attributed to the effect of pH on the PET process. The successful combination of logic switch and SiNWs provides a rational approach to assemble different logic molecules on SiNWs for realization of miniaturization and modularization of switches and logic devices.

[Fluorescence-guided surgery with 5-aminolevulinic acid for resection of malignant gliomas--a new treatment modality].

PubMed

Cortnum, Søren; Laursen, Rene

2013-02-25

5-aminolevulinic acid (ALA) is a precursor of haemoglobin which leads to the synthesis of porphyrins in malignant gliomas which then appears with red fluorescence under blue light. In the literature we see that there is class Ib evidence that 5-ALA guided surgery significantly increases the radicalism of surgery and gives rise to a marked improvement in 6-month progression-free survival and that there is now class II evidence confirming the value of maximal cytoreductive surgery. Furthermore, existing class II evidence indicates that there is a synergistic effect between aggressive cytoreductive surgery and radiochemotherapy.

Synthesis of two fluorescent GTPγS molecules and their biological relevance.

PubMed

Trans, Denise J; Bai, Ruoli; Addison, J Bennet; Liu, Ruiwu; Hamel, Ernest; Coleman, Matthew A; Henderson, Paul T

2017-06-03

Fluorescent GTP analogues are utilized for an assortment of nucleic acid and protein characterization studies. Non-hydrolysable analogues such as GTPγS offer the advantage of keeping proteins in a GTP-bound conformation due to their resistance to hydrolysis into GDP. Two novel fluorescent GTPγS molecules were developed by linking fluorescein and tetramethylrhodamine to the γ-thiophosphate of GTPγS. Chemical and biological analysis of these two compounds revealed their successful synthesis and ability to bind to the nucleotide-binding site of tubulin. These two new fluorescent non-hydrolysable nucleotides offer new possibilities for biophysical and biochemical characterization of GTP-binding proteins.

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

One-step synthesis of nitrogen, boron co-doped fluorescent carbon nanoparticles for glucose detection.

PubMed

Liang, Meijuan; Ren, Yi; Zhang, Haijuan; Ma, Yunxia; Niu, Xiaoying; Chen, Xingguo

2017-09-01

Heteroatom-doped carbon nanoparticles (CNPs) have attracted considerable attention due to an effective improvement in their intrinsic properties. Here, a facile and simple synthesis of nitrogen, boron co-doped carbon nanoparticles (NB-CNPs) from a sole precursor, 3-aminophenylboronic acid, was performed via a one-step solid-phase approach. Because of the presence of boronic acid, NB-CNPs can be used directly as a fluorescent probe for glucose. Based on a boronic acid-triggered specific reaction, we developed a simple NB-CNP probe without surface modification for the detection of glucose. When glucose was introduced, the fluorescence of NB-CNPs was suppressed through a surface-quenching states mechanism. Obvious fluorescence quenching allowed the highly sensitive determination of glucose with a limit of detection of 1.8 μM. Moreover, the proposed method has been successfully used to detect glucose in urine from people with diabetes, suggesting potential application in sensing glucose. Copyright © 2017 John Wiley & Sons, Ltd.

Preparation and Characterization of Fluorescent SiO2 Microspheres

NASA Astrophysics Data System (ADS)

Xu, Cui; Zhang, Hao; Guan, Ruifang

2018-01-01

Fluorescent compound without typical fluorophores was synthesized with citric acid (CA) and aminopropyltriethoxysilane (APTS) firstly, and then it was grafted to the surface of the prepared SiO2 microspheres by chemical reaction. The fluorescent SiO2 microspheres with good fluorescent properties were obtained by optimizing the reaction conditions. And the morphology and structure of the fluorescent SiO2 microspheres have been characterized by scanning electron microscopy (SEM) and fourier transform infrared (FTIR) spectroscopy. The results showed that the preparation of fluorescent SiO2 microspheres have good monodispersity and narrow particle size distribution. Moreover, the fluorescent SiO2 microspheres can be applied to detect Fe3+ in aqueous solution, prepare fluorescent SiO2 rubber, and have potential to be applied in the fluorescent labeling and fingerprint appearing technique fields.

Multifunctional magnetic and fluorescent core-shell nanoparticles for bioimaging.

PubMed

Lu, Yanjiao; He, Bicheng; Shen, Jie; Li, Jie; Yang, Wantai; Yin, Meizhen

2015-02-07

Novel magnetic and fluorescent core-shell nanoparticles have been fabricated, which exhibit superparamagnetic behavior and emit strong near-infrared fluorescence. The nanoparticles are highly biocompatible and can be internalized into cells with nucleic accumulation via strong interaction with nucleic acids, implying potential applications in the biomedical field.

Intestine pH measurements using fluorescence imaging: an in-vivo preliminary study

NASA Astrophysics Data System (ADS)

Marechal, Xavier-Marie; Mordon, Serge R.; Devoisselle, Jean-Marie; Begu, Sylvie; Mathieu, D.; Buys, Bruno; Dhelin, Guy; Lesage, Jean C.; Neviere, Remi; Chopin, Claude

1999-02-01

Measurement of gastrointestinal intramucosal pH has been recognized as an important factor in the detection of hypoxia-induced dysfunctions. However, current pH measurement techniques are limited in terms of time and spatial resolution. A major advance in accurate pH measurement was the development of the ratiometric fluorescent indicator dye, 2',7'-bis(carboxyethyl)-4,5- carboxyfluorescein (BCECF). This study aimed to demonstrate the feasibility of fluorescence imaging technique to measure in vivo the pH of intestine. The intestine was inserted in an optical chamber placed under a microscope. Animals were injected i.v. with the pH-sensitive fluorescent dye BCECF. Fluorescence was visualized by illuminating the intestine alternately at 490 and 470 nm. The emitted fluorescence was directed to an intensified camera. The ratio of emitted fluorescence at excitation wavelengths of 490 and 470 nm was measured, corrected and converted to pH by constructing a calibration curve. The pH controls were performed with a pH microelectrode correlated with venous blood gas sampling. We concluded that accurate pH measurements of rat intestine can be obtained by fluorescence imaging using BCECF. This technology could be easily adapted for endoscopic pH measurement.

An efficient and sensitive fluorescent pH sensor based on amino functional metal-organic frameworks in aqueous environment.

PubMed

Xu, Xiao-Yu; Yan, Bing

2016-04-28

A pH sensor is fabricated via a reaction between an Al(III) salt and 2-aminoterephthalic acid in DMF which leads to a MOF (Al-MIL-101-NH2) with free amino groups. The Al-MIL-101-NH2 samples show good luminescence and an intact structure in aqueous solutions with pH ranging from 4.0 to 7.7. Given its exceptional stability and pH-dependent fluorescence intensity, Al-MIL-101-NH2 has been applied to fluorescent pH sensing. Significantly, in the whole experimental pH range (4.0-7.7), the fluorescence intensity almost increases with increasing pH (R(2) = 0.99688) which can be rationalized using a linear equation: I = 2.33 pH + 26.04. In addition, error analysis and cycling experiments have demonstrated the accuracy and utilizability of the sensor. In practical applications (PBS and lake water), Al-MIL-101-NH2 also manifests its analytical efficiency in pH sensing. And the samples can be easily isolated from an aqueous solution by incorporating Fe3O4 nanoparticles. Moreover, the possible sensing mechanism based on amino protonation is discussed in detail. This work is on of the few cases for integrated pH sensing systems in aqueous solution based on luminescent MOFs.

Fluorescence changes in remineralized and nonremineralized enamel adjacent to glass ionomer ART restorations: an in vitro study.

PubMed

Gaskin, Elizabeth B; Harless, Jeffrey D; Wefel, James S; Guzmán-Armstrong, Sandra; Armstrong, Steven R; Vargas, Marcos A; Hernández, Maria Marcela; Qian, Fang

2007-01-01

The purpose of this study was to evaluate fluorescence changes of remineralized and nonremineralized enamel margins adjacent to glass ionomer restorations during a pH cycling sequence. One hundred permanent molar and premolar teeth were placed in a demineralizing solution for 3 days and restored with a glass ionomer restoration (simulating Atraumatic Restorative Treatment [ART]). Half were placed in a remin solution for 7 days to create a remineralization (remin) group. Specimens were randomly divided into 4 groups (N=25): (a) 2 remin groups; and (b) 2 nonremin groups. One half of the remin and nonremin group specimens were treated with a 5,000-ppm sodium fluoride solution during pH cycling with remin fluid and an acidic beverage over 20 days. Fluorescence changes were recorded with quantitative light fluorescence (QLF). Higher fluorescence values indicated less lesion porosity. Statistical comparisons between the groups over the 5 measurement sessions of cycling were performed using repeated measures of analysis of variance with a post-hoc test, paired-sample t test and 2-sample t tests (alpha=0.05). The remin groups experienced significantly less lesion porosity than the nonremin groups. Fluoride groups experienced less lesion porosity than the nonfluoride groups. A brief period of remineralization and use of a prescription strength fluoridated rinse improved the enamel substrate surrounding glass ionomer restorations, resulting in less lesion porosity.

NIR-to-visible upconversion nanoparticles for fluorescent labeling and targeted delivery of siRNA

NASA Astrophysics Data System (ADS)

Jiang, Shan; Zhang, Yong; Lim, Kian Meng; Sim, Eugene K. W.; Ye, Lei

2009-04-01

Near-infrared (NIR)-to-visible upconversion fluorescent nanoparticles were synthesized and used for imaging and targeted delivery of small interfering RNA (siRNA) to cancer cells. Silica-coated NaYF4 upconversion nanoparticles (UCNs) co-doped with lanthanide ions (Yb/Er) were synthesized. Folic acid and anti-Her2 antibody conjugated UCNs were used to fluorescently label the folate receptors of HT-29 cells and Her2 receptors of SK-BR-3 cells, respectively. The intracellular uptake of the folic acid and antibody conjugated UCNs was visualized using a confocal fluorescence microscope equipped with an NIR laser. siRNA was attached to anti-Her2 antibody conjugated UCNs and the delivery of these nanoparticles to SK-BR-3 cells was studied. Meanwhile, a luciferase assay was established to confirm the gene silencing effect of siRNA. Upconversion nanoparticles can serve as a fluorescent probe and delivery system for simultaneous imaging and delivery of biological molecules.

A compact multi-channel fluorescence sensor with ambient light suppression

NASA Astrophysics Data System (ADS)

Egly, Dominik; Geörg, Daniel; Rädle, Matthias; Beuermann, Thomas

2012-03-01

A multi-channel fluorescence sensor has been developed for process monitoring and fluorescence diagnostics. It comprises a fiber-optic set-up with an immersion probe and an intensity-modulated high power ultraviolet light-emitting diode as a light source for fluorescence excitation. By applying an electronic lock-in procedure, fluorescence signals are selectively detectable at ambient light levels of 1000 000 times higher intensity. The sensor was designed to be compact, low cost and easily adaptable to a wide field of application. The set-up was used to simultaneously monitor three important metabolic fluorophores: NAD(P)H, flavins and porphyrins during the cultivation of a baker's yeast. Moreover, the accumulation and degradation kinetics of protoporphyrin IX induced by 5-aminolevulinic acid on the skin could be recorded by the sensor. The detection limit for protoporphyrin IX was determined to be 4 × 10-11 mol L-1. The linear signal amplification of the sensor and time courses of fluorescence signals monitored during yeast fermentations were validated using a commercial CCD spectrometer. The robust and flexible set-up of the fiber-optic measurement system promises easy implementation of this non-invasive analytical tool to fluorescence monitoring and diagnostics in R&D and production.

Preferential adsorption of fluorescing fulvic and humic acid components on activated carbon using flow field-flow fractionation analysis.

PubMed

Schmit, Kathryn H; Wells, Martha J M

2002-02-01

Activated carbon treatment of drinking water is used to remove natural organic matter (NOM) precursors that lead to the formation of disinfection byproducts. The innate hydrophobic nature and macromolecular size of NOM render it amenable to sorption by activated carbon. Batch equilibrium and minicolumn breakthrough adsorption studies were performed using granular activated carbon to treat NOM-contaminated water. Ultraviolet (UV) absorption spectroscopy and flow field-flow fractionation analysis using tandem diode-array and fluorescence detectors were used to monitor the activated carbon sorption of NOM. Using these techniques, it was possible to study activated carbon adsorption properties of UV absorbing, fluorescing and nonfluorescing, polyelectrolytic macromolecules fractionated from the total macromolecular and nonmacromolecular composition of NOM. Adsorption isotherms were constructed at pH 6 and pH 9. Data were described by the traditional and modified Freundlich models. Activated carbon capacity and adsorbability were compared among fractionated molecular subsets of fulvic and humic acids. Preferential adsorption (or adsorptive fractionation) of polyelectrolytic, fluorescing fulvic and humic macromolecules on activated carbon was observed. The significance of observing preferential adsorption on activated carbon of fluorescing macromolecular components relative to nonfluorescing components is that this phenomenon changes the composition of dissolved organic matter remaining in equilibrium in the aqueous phase relative to the composition that existed in the aqueous phase prior to adsorption. Likewise, it changes the composition of dissolved organic matter remaining in equilibrium in the aqueous phase relative to the adsorbed phase. This research increases our understanding of NOM interactions with activated carbon which may lead to improved methods of potable water production.

Fluorescence-guided resection of intracranial VX2 tumor in a preclinical model using 5-aminolevulinic acid (ALA): preliminary results

NASA Astrophysics Data System (ADS)

Bogaards, Arjen; Varma, Abhay; Moriyama, Eduardo H.; Lin, Annie; Giles, Anoja; Bisland, Stuart K.; Lilge, Lothar D.; Bilbao, G. M.; Muller, Paul J.; Wilson, Brian C.

2003-06-01

Fluorescence-guided brain tumor resection may help the neurosurgeon to identify tumor margins that merge imperceptibly into the normal brain tissue and are difficult to identify under white light illumination even using an operating microscope. We compared the amount of residual tumor after white light resection using an operating microscope versus that after fluorescnece-guided resection of an intracranial VX2 tumor in a preclinical model using our previously developed co-axial fluorscence imaging and spectroscopy system, exciting and detecting PpIX fluorescence at 405nm and 635nm respectively. Preliminary results: No fluorescence was present in 3 non-tumor-bearing animals. Fluorescence was present in all 15 tumor-bearing animals after white light resection was completed. To date in 4 rabbits, a decrease in residual tumor was found when using additional fluorescence guided resection compared to white light resection only. Conclusions: ALA induced PpIX fluorescence detects tumor margins not seen under an operation microscope using while light. Using fluorescence imaging to guide tumor resection resulted in a 3-fold decrease in the amount of residual timor. However, these preliminary results indicate that also an additional amount of normal brain is resected, which will be further investigated.

High speed nucleic acid sequencing

DOEpatents

Korlach, Jonas [Ithaca, NY; Webb, Watt W [Ithaca, NY; Levene, Michael [Ithaca, NY; Turner, Stephen [Ithaca, NY; Craighead, Harold G [Ithaca, NY; Foquet, Mathieu [Ithaca, NY

2011-05-17

The present invention is directed to a method of sequencing a target nucleic acid molecule having a plurality of bases. In its principle, the temporal order of base additions during the polymerization reaction is measured on a molecule of nucleic acid. Each type of labeled nucleotide comprises an acceptor fluorophore attached to a phosphate portion of the nucleotide such that the fluorophore is removed upon incorporation into a growing strand. Fluorescent signal is emitted via fluorescent resonance energy transfer between the donor fluorophore and the acceptor fluorophore as each nucleotide is incorporated into the growing strand. The sequence is deduced by identifying which base is being incorporated into the growing strand.

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.

Low light CMOS contact imager with an integrated poly-acrylic emission filter for fluorescence detection.

PubMed

Dattner, Yonathan; Yadid-Pecht, Orly

2010-01-01

This study presents the fabrication of a low cost poly-acrylic acid (PAA) based emission filter integrated with a low light CMOS contact imager for fluorescence detection. The process involves the use of PAA as an adhesive for the emission filter. The poly-acrylic solution was chosen due its optical transparent properties, adhesive properties, miscibility with polar protic solvents and most importantly its bio-compatibility with a biological environment. The emission filter, also known as an absorption filter, involves dissolving an absorbing specimen in a polar protic solvent and mixing it with the PAA to uniformly bond the absorbing specimen and harden the filter. The PAA is optically transparent in solid form and therefore does not contribute to the absorbance of light in the visible spectrum. Many combinations of absorbing specimen and polar protic solvents can be derived, yielding different filter characteristics in different parts of the spectrum. We report a specific combination as a first example of implementation of our technology. The filter reported has excitation in the green spectrum and emission in the red spectrum, utilizing the increased quantum efficiency of the photo sensitive sensor array. The thickness of the filter (20 μm) was chosen by calculating the desired SNR using Beer-Lambert's law for liquids, Quantum Yield of the fluorophore and the Quantum Efficiency of the sensor array. The filters promising characteristics make it suitable for low light fluorescence detection. The filter was integrated with a fully functional low noise, low light CMOS contact imager and experimental results using fluorescence polystyrene micro-spheres are presented.

Fluorescent Endoscopy of Tumors in Upper Part of Gastrointestinal Tract

NASA Astrophysics Data System (ADS)

Borisova, E.; Vladimirov, B.; Angelov, I.; Avramov, L.

2007-04-01

In the recent study delta-aminolevulinic acid/Protoporphyrin IX (5-ALA/PpIX) is used as fluorescent marker for dysplasia and tumor detection in esophagus and stomach. The 5-ALA is administered per os six hours before measurements at dose 20mg/kg weight. High-power light-emitting diode at 405 nm is used as an excitation source. Special opto-mechanical device is built for LED to use the light guide of standard video-endoscopic system (Olimpus Corp.). Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer (USB4000, OceanOptics Inc.). Very good correlation between fluorescence signals and histology examination of the lesions investigated is achieved.

"Use of acidophilic bacteria of the genus Acidithiobacillus to biosynthesize CdS fluorescent nanoparticles (quantum dots) with high tolerance to acidic pH".

PubMed

Ulloa, G; Collao, B; Araneda, M; Escobar, B; Álvarez, S; Bravo, D; Pérez-Donoso, J M

2016-12-01

The use of bacterial cells to produce fluorescent semiconductor nanoparticles (quantum dots, QDs) represents a green alternative with promising economic potential. In the present work, we report for the first time the biosynthesis of CdS QDs by acidophilic bacteria of the Acidithiobacillus genus. CdS QDs were obtained by exposing A. ferrooxidans, A. thiooxidans and A. caldus cells to sublethal Cd 2+ concentrations in the presence of cysteine and glutathione. The fluorescence of cadmium-exposed cells moves from green to red with incubation time, a characteristic property of QDs associated with nanocrystals growth. Biosynthesized nanoparticles (NPs) display an absorption peak at 360nm and a broad emission spectra between 450 and 650nm when excited at 370nm, both characteristic of CdS QDs. Average sizes of 6 and 10nm were determined for green and red NPs, respectively. The importance of cysteine and glutathione on QDs biosynthesis in Acidithiobacillus was related with the generation of H 2 S. Interestingly, QDs produced by acidophilic bacteria display high tolerance to acidic pH. Absorbance and fluorescence properties of QDs was not affected at pH 2.0, a condition that totally inhibits the fluorescence of QDs produced chemically or biosynthesized by mesophilic bacteria (stable until pH 4.5-5.0). Results presented here constitute the first report of the generation of QDs with improved properties by using extremophile microorganisms. Copyright © 2016 Elsevier Inc. All rights reserved.

Interactions between α-amylase and an acidic branched polysaccharide from green tea.

PubMed

Wu, Shuyun; Lai, Minghua; Luo, Jiahao; Pan, Jingwen; Zhang, Li-Ming; Yang, Liqun

2017-01-01

To understand the mechanism responsible for the α-amylase inhibitory activity of tea polysaccharides, the interaction between α-amylase and an acidic branched tea polysaccharide (TPSA) was investigated using fluorescence spectroscopy and resonance light scattering analysis. TPSA, exhibiting inhibitory activity towards α-amylase (the maximum inhibition percentage of 65%), was isolated from green tea (Camellia sinensis) and characterized by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and gas chromatography. Synchronous fluorescence spectroscopy revealed that the binding interaction between the tryptophan residues of α-amylase and TPSA was predominant. Based on the fluorescence quenching effect of tryptophan residues induced by TPSA, the binding constants between α-amylase and TPSA were determined to be 18.6×10 6 , 8.0×10 6 and 4.6×10 6 L·mol -1 at 20, 30 and 37°C, respectively. The calculated Gibbs free-energy changes were negative, indicating that the bonding interaction was a spontaneous process. The enthalpy and the entropy changes were -62.13 KJ·mol -1 and -0.0728 KJ·mol -1 ·K -1 , suggesting that hydrogen bonding interactions might play a major role in the binding process. The formation of an α-amylase/TPSA complex was evidenced by fluorescence quenching and resonance light scattering analysis, and this complex could be the main contributor to the α-amylase inhibitory activity of TPSA. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhanced characterization of oil sands acid-extractable organics fractions using electrospray ionization-high-resolution mass spectrometry and synchronous fluorescence spectroscopy.

PubMed

Bauer, Anthony E; Frank, Richard A; Headley, John V; Peru, Kerry M; Hewitt, L Mark; Dixon, D George

2015-05-01

The open pit oil sands mining operations north of Fort McMurray, Alberta, Canada, are accumulating tailings waste at a rate approximately equal to 4.9 million m(3) /d. Naphthenic acids are among the most toxic components within tailings to aquatic life, but structural components have largely remained unidentified. In the present study, electrospray ionization high-resolution mass spectrometry (ESI-HRMS) and synchronous fluorescence spectroscopy (SFS) were used to characterize fractions derived from the distillation of an acid-extractable organics (AEO) mixture isolated from oil sands process-affected water (OSPW). Mean molecular weights of each fraction, and their relative proportions to the whole AEO extract, were as follows: fraction 1: 237 Da, 8.3%; fraction 2: 240 Da, 23.8%; fraction 3: 257 Da, 26.7%; fraction 4: 308 Da, 18.9%; fraction 5: 355 Da, 10.0%. With increasing mean molecular weight of the AEO fractions, a concurrent increase occurred in the relative abundance of nitrogen-, sulfur-, and oxygen-containing ions, double-bond equivalents, and degree of aromaticity. Structures present in the higher-molecular-weight fractions (fraction 4 and fraction 5) suggested the presence of heteroatoms, dicarboxyl and dihydroxy groups, and organic acid compounds with the potential to function as estrogens. Because organic acid compositions become dominated by more recalcitrant, higher-molecular-weight acids during natural degradation, these findings are important in the context of oil sands tailings pond water remediation. © 2015 SETAC.

Microwave-induced facile synthesis of water-soluble fluorogenic alginic acid derivatives.

PubMed

Chhatbar, Mahesh U; Meena, Ramavatar; Prasad, Kamalesh; Chejara, Dharmesh R; Siddhanta, A K

2011-04-01

A facile microwave-induced method was developed for synthesizing water-soluble fluorescent derivatives of alginic acid (ALG) with four different diamines, hydrazine (HY), ethylenediamine (EDA), 1,6-hexanediamine (HDA), and 1,4-cyclohexanediamine (CHDA), followed by a cross-linking reaction with a natural cross linker genipin. The ethylenediamine derivative of alginic acid (ALG-EDA) exhibited good fluorescent activity, which upon cross linking was enhanced threefold. The other amide derivatives, for example, ALG-HY, ALG-HDA, and ALG-CHDA, were not fluorescent, but their respective crosslinked products exhibited excellent fluorescent activity. The fluorescence intensity had an inverse correlation with the number of carbon atoms present in the amine, which in turn was a function of degree of substitution (DS). These fluorescent polysaccharide derivatives are of potential utility in the domain of sensor applications. Copyright © 2011 Elsevier Ltd. All rights reserved.

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.

Limitations of fluorescence spectroscopy to characterize organic matter in engineered systems

NASA Astrophysics Data System (ADS)

Korak, J.

2017-12-01

Fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in engineered systems, such as drinking water, municipal wastewater and industrial water treatment. While fluorescence data collected in water treatment applications has led to the development of strong empirical relationships between fluorescence responses and process performance, the use of fluorescence to infer changes in the underlying organic matter chemistry is often oversimplified and applied out of context. Fluorescence only measures a small fraction of DOM as fluorescence quantum yields are less than 5% for many DOM sources. Relying on fluorescence as a surrogate for DOM presence, character or reactivity may not be appropriate for systems where small molecular weight, hydrophilic constituents unlikely to fluoresce are important. In addition, some methods rely on interpreting fluorescence signals at different excitation wavelengths as a surrogate for operationally-defined humic- and fulvic-acids in lieu of traditional XAD fractionation techniques, but these approaches cannot be supported by other lines of evidence considering natural abundance and fluorescence quantum yields of these fractions. These approaches also conflict with parallel factor analysis (PARAFAC), a statistical approach that routinely identifies fluorescence components with dual excitation behavior. Lastly, methods developed for natural systems are often applied out of context to engineered systems. Fluorescence signals characteristic of phenols or indoles are often interpreted as indicators for biological activity in natural systems due to fluorescent amino acids and peptides, but this interpretation is may not be appropriate in engineering applications where non-biological sources of phenolic functional groups may be present. This presentation explores common fluorescence interpretation approaches, discusses the limitations and provides recommendations related to engineered systems.

On-line Ammonia Sensor and Invisible Security Ink by Fluorescent Zwitterionic Spirocyclic Meisenheimer Complex

PubMed Central

Das, Tanmay; Pramanik, Apurba; Haldar, Debasish

2017-01-01

Ammonia is not only a highly important gas for civilization but also contribute significantly for climate change and human health hazard. Highly sensitive ammonia sensor has been developed from a fluorescent zwitterionic spirocyclic Meisenheimer complex. Moreover, formation of this Meisenheimer complex can also be utilized for selective as well as naked eye instant detection of nitro aromatic explosive picric acid. The presence of a quaternary nitrogen atom directly attached to the spiro carbon is the unique feature of this Meisenheimer complex. This excellent photoluminescent (PL) Meisenheimer complex has two distinct stimuli responsive sites. One is sensitive towards acid while the other one is towards the base. These two positions can be modulated by adding one equivalent acid and one equivalent base to result two new products which are non fluorescent. One of these two non fluorescent species was found very exciting because of its UV/Vis transparency. Utilizing this concept we have fabricated an on-line sensor for measuring ammonia in dry or humid and condensing sewer air. The sensor was robust against ambient temperature and humidity variation. We have also developed an invisible ink from this Meisenheimer complex, with potential application for security purpose. PMID:28091542

On-line Ammonia Sensor and Invisible Security Ink by Fluorescent Zwitterionic Spirocyclic Meisenheimer Complex.

PubMed

Das, Tanmay; Pramanik, Apurba; Haldar, Debasish

2017-01-16

Ammonia is not only a highly important gas for civilization but also contribute significantly for climate change and human health hazard. Highly sensitive ammonia sensor has been developed from a fluorescent zwitterionic spirocyclic Meisenheimer complex. Moreover, formation of this Meisenheimer complex can also be utilized for selective as well as naked eye instant detection of nitro aromatic explosive picric acid. The presence of a quaternary nitrogen atom directly attached to the spiro carbon is the unique feature of this Meisenheimer complex. This excellent photoluminescent (PL) Meisenheimer complex has two distinct stimuli responsive sites. One is sensitive towards acid while the other one is towards the base. These two positions can be modulated by adding one equivalent acid and one equivalent base to result two new products which are non fluorescent. One of these two non fluorescent species was found very exciting because of its UV/Vis transparency. Utilizing this concept we have fabricated an on-line sensor for measuring ammonia in dry or humid and condensing sewer air. The sensor was robust against ambient temperature and humidity variation. We have also developed an invisible ink from this Meisenheimer complex, with potential application for security purpose.

On-line Ammonia Sensor and Invisible Security Ink by Fluorescent Zwitterionic Spirocyclic Meisenheimer Complex

NASA Astrophysics Data System (ADS)

Das, Tanmay; Pramanik, Apurba; Haldar, Debasish

2017-01-01

Ammonia is not only a highly important gas for civilization but also contribute significantly for climate change and human health hazard. Highly sensitive ammonia sensor has been developed from a fluorescent zwitterionic spirocyclic Meisenheimer complex. Moreover, formation of this Meisenheimer complex can also be utilized for selective as well as naked eye instant detection of nitro aromatic explosive picric acid. The presence of a quaternary nitrogen atom directly attached to the spiro carbon is the unique feature of this Meisenheimer complex. This excellent photoluminescent (PL) Meisenheimer complex has two distinct stimuli responsive sites. One is sensitive towards acid while the other one is towards the base. These two positions can be modulated by adding one equivalent acid and one equivalent base to result two new products which are non fluorescent. One of these two non fluorescent species was found very exciting because of its UV/Vis transparency. Utilizing this concept we have fabricated an on-line sensor for measuring ammonia in dry or humid and condensing sewer air. The sensor was robust against ambient temperature and humidity variation. We have also developed an invisible ink from this Meisenheimer complex, with potential application for security purpose.

Hydrophilic interaction liquid chromatography of anthranilic acid-labelled oligosaccharides with a 4-aminobenzoic acid ethyl ester-labelled dextran hydrolysate internal standard.

PubMed

Neville, David C A; Alonzi, Dominic S; Butters, Terry D

2012-04-13

Hydrophilic interaction liquid chromatography (HILIC) of fluorescently labelled oligosaccharides is used in many laboratories to analyse complex oligosaccharide mixtures. Separations are routinely performed using a TSK gel-Amide 80 HPLC column, and retention times of different oligosaccharide species are converted to glucose unit (GU) values that are determined with reference to an external standard. However, if retention times were to be compared with an internal standard, consistent and more accurate GU values would be obtained. We present a method to perform internal standard-calibrated HILIC of fluorescently labelled oligosaccharides. The method relies on co-injection of 4-aminobenzoic acid ethyl ester (4-ABEE)-labelled internal standard and detection by UV absorption, with 2-AA (2-aminobenzoic acid)-labelled oligosaccharides. 4-ABEE is a UV chromophore and a fluorophore, but there is no overlap of the fluorescent spectrum of 4-ABEE with the commonly used fluorescent reagents. The dual nature of 4-ABEE allows for accurate calculation of the delay between UV and fluorescent signals when determining the GU values of individual oligosaccharides. The GU values obtained are inherently more accurate as slight differences in gradients that can influence retention are negated by use of an internal standard. Therefore, this paper provides the first method for determination of HPLC-derived GU values of fluorescently labelled oligosaccharides using an internal calibrant. Copyright © 2012 Elsevier B.V. All rights reserved.

N,N-Diethylamine appended binuclear Zn(ii) complexes: highly selective and sensitive fluorescent chemosensors for picric acid.

PubMed

Kumar, Amit; Kumar, Ashish; Pandey, Daya Shankar