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Showing papers on "Fluorescence spectrometry published in 2009"


Journal ArticleDOI
TL;DR: It is concluded that the sensitive detection of contamination events in recycled water systems may be achieved by monitoring Peak T and/or Peak C fluorescence.

845 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated achievable uncertainties for the determination of fluorescence quantum yields of these chromophores and illustrate common pitfalls exemplarily for differently sized water-soluble CdTe QDs.
Abstract: Despite the increasing use of semiconductor nanocrystals (quantum dots, QDs) with unique size-controlled optical and chemical properties in (bio)analytical detection, biosensing and fluorescence imaging and the obvious relevance of reliable values of fluorescence quantum yields for these applications, evaluated procedures for the determination of the fluorescence quantum yields (Φf) of these materials are still missing. This limits the value of literature data of QDs in comparison to common organic dyes and hampers the comparability of the performance of QDs from different sources or manufacturers. This encouraged us to investigate achievable uncertainties for the determination of Φf values of these chromophores and to illustrate common pitfalls exemplarily for differently sized water-soluble CdTe QDs. Special attention is dedicated to the colloidal nature and complicated surface chemistry of QDs thereby deriving procedures to minimize uncertainties related to these features.

566 citations


Journal ArticleDOI
TL;DR: No "ideal" technique was found for characterizing manufactured nanoparticles in an environmental context as each technique had its own advantages and limitations.
Abstract: Sizes of stabilized (24 h) nanoparticle suspensions were determined using several state-of-the-art analytical techniques (transmission electron microscopy; atomic force microscopy; dynamic light scattering; fluorescence correlation spectroscopy; nanoparticle tracking analysis; flow field flow fractionation). Theoretical and analytical considerations were evaluated, results were compared, and the advantages and limitations of the techniques were discussed. No "ideal" technique was found for characterizing manufactured nanoparticles in an environmental context as each technique had its own advantages and limitations.

545 citations


Journal ArticleDOI
TL;DR: During long-term operation of the MBR, bound EPS demonstrated positive correlations with membrane fouling while temperature was verified as a negative factor affecting EPS concentration and loosely bound EPS (LB-EPS) showed more significant correlations with membranes fouling.

526 citations


Journal ArticleDOI
Xinwei Lu1, Lijun Wang1, Kai Lei1, Jing Huang1, Yuxiang Zhai1 
TL;DR: The results indicate that, in comparison with Chinese soil, street dusts in Baoji have elevated metal concentrations as a whole and IPI indicates heavy metals of street dust polluted seriously.

457 citations


Journal ArticleDOI
TL;DR: Under the conditions studied here, nanoparticle dispersions were often stable for environmentally relevant conditions of SRFA, pH, and ionic strength, suggesting that in the natural environment, TiO2 dispersion might occur to a greater extent than expected.
Abstract: The increasing use of nanomaterials in consumer products has led to increased concerns about their potential environmental and health impacts. To better understand the transport, fate, and behavior of nanoparticles in aquatic systems, it is essential to understand their interactions with different components of natural waters including natural organic matter over a broad range of physicochemical conditions. Fluorescence correlation spectroscopy was used to determine the diffusion coefficients of TiO2 nanoparticles having a nominal size of 5 nm. The effects of a various concentrations of the Suwannee River Fulvic Acid (SRFA) and the roles of pH and ionic strength were evaluated. Aggregation of the bare TiO2 nanoparticles increased for pH values near the zero point of charge. At any given pH, an increase in ionic strength generally resulted in increased aggregation. Furthermore, conditions which favored adsorption of the SRFA resulted in less aggregation of the TiO2 nanoparticles, presumably due to increase...

452 citations


Journal ArticleDOI
TL;DR: Both the color and fluorescence changes of the chemosensor are remarkably specific for Cu(2+) in the presence of other heavy and transition metal ions (even those that exist in high concentration), which meet the selective requirements for biomedical and environmental monitoring application.
Abstract: The design and synthesis of a novel rhodamine spirolactam derivative and its application in fluorescent detections of Cu(2+) in aqueous solution and living cells are reported. The signal change of the chemosensor is based on a specific metal ion induced reversible ring-opening mechanism of the rhodamine spirolactam. It exhibits a highly sensitive "turn-on" fluorescent response toward Cu(2+) in aqueous solution with an 80-fold fluorescence intensity enhancement under 10 equiv of Cu(2+) added. This indicates that the synthesized chemosensor effectively avoided the fluorescence quenching for the paramagnetic nature of Cu(2+) via its strong binding capability toward Cu(2+). With the experimental conditions optimized, the probe exhibits a dynamic response range for Cu(2+) from 8.0 x 10(-7) to 1.0 x 10(-5) M, with a detection limit of 3.0 x 10(-7) M. The response of the chemosensor for Cu(2+) is instantaneous and reversible. Most importantly, both the color and fluorescence changes of the chemosensor are remarkably specific for Cu(2+) in the presence of other heavy and transition metal ions (even those that exist in high concentration), which meet the selective requirements for biomedical and environmental monitoring application. The proposed chemosensor has been used for direct measurement of Cu(2+) content in river water samples and imaging of Cu(2+) in living cells with satisfying results, which further demonstrates its value of practical applications in environmental and biological systems.

417 citations


Journal ArticleDOI
TL;DR: Three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy was employed to characterize dissolved organic matter (DOM) in a submerged membrane bioreactor (MBR), and it was found that the dominant fluorescence substances in membrane foulants were protein-like substances.

402 citations


Journal ArticleDOI
Liqin Xiong1, Zhigang Chen1, Qiwei Tian1, Tianye Cao1, Congjian Xu1, Fuyou Li1 
TL;DR: Results demonstrate that the UCL imaging technique appears particularly suited for applications in tracking and labeling components of complex biological systems.
Abstract: Fluorescence targeted imaging in vivo has proven useful in tumor recognition and drug delivery. In the process of in vivo imaging, however, a high autofluorescence background could mask the signals from the fluorescent probes. Herein, a high contrast upconversion luminescence (UCL) imaging protocol was developed for targeted imaging of tumors based on RGD-labeled upconversion nanophosphors (UCNPs) as luminescent labels. Confocal Z-scan imaging of tissue slices revealed that UCL imaging showed no autofluorescence signal even at high penetration depth (∼600 μm). More importantly, region of interest (ROI) analysis of the UCL signal in vivo showed that UCL imaging achieved a high signal-to-noise ratio (∼24) between the tumor and the background. These results demonstrate that the UCL imaging technique appears particularly suited for applications in tracking and labeling components of complex biological systems.

369 citations


Journal ArticleDOI
TL;DR: Demonstration of quantitative colorimetric correlations using a scanner or camera to image the zones and to measure the intensity of color, makes it possible to conduct assays without a microplate reader.
Abstract: This paper describes 96- and 384-microzone plates fabricated in paper as alternatives to conventional multiwell plates fabricated in molded polymers. Paper-based plates are functionally related to plastic well plates, but they offer new capabilities. For example, paper-microzone plates are thin (∼180 μm), require small volumes of sample (5 μL per zone), and can be manufactured from inexpensive materials ($0.05 per plate). The paper-based plates are fabricated by patterning sheets of paper, using photolithography, into hydrophilic zones surrounded by hydrophobic polymeric barriers. This photolithography used an inexpensive formulation photoresist that allows rapid (∼15 min) prototyping of paper-based plates. These plates are compatible with conventional microplate readers for quantitative absorbance and fluorescence measurements. The limit of detection per zone loaded for fluorescence was 125 fmol for fluorescein isothiocyanate-labeled bovine serum albumin, and this level corresponds to 0.02 the quantity o...

369 citations


Journal ArticleDOI
TL;DR: To the best of the knowledge, this is the first example of a single DNA-based sensor that allows the detection of both Hg(2+) and Pb( 2+) ions.
Abstract: We have developed a technique for the highly selective and sensitive detection of Pb(2+) and Hg(2+) using a thrombin-binding aptamer (TBA) probe labeled with the donor carboxyfluorescein (FAM) and the quencher 4-([4-(dimethylamino)phenyl]azo)benzoic acid (DABCYL) at its 5' and 3' termini, respectively. The TBA has a random coil structure that changes into a G-quartet structure and a hairpin-like structure upon binding Pb(2+) and Hg(2+) ions, respectively. As a result, the fluorescence decreases through fluorescence resonance energy transfer (FRET) between the fluorophore and quencher. These changes in fluorescence intensity allow the selective detection of Pb(2+) and Hg(2+) ions at concentrations as low as 300 pM and 5.0 nM using this TBA probe in the presence of phytic acid and a random DNA/NaCN mixture, respectively. The linear correlation existed between the fluorescence intensity and the concentration of Pb(2+) and Hg(2+) over the range of 0.5-30 nM (R(2) = 0.98) and 10-200 nM (R(2) = 0.98), respectively. To the best of our knowledge, this is the first example of a single DNA-based sensor that allows the detection of both Hg(2+) and Pb(2+) ions. This simple and cost-effective probe was also applied to separately determine Pb(2+) in soil samples and spiked Hg(2+) in pond samples.

Journal ArticleDOI
TL;DR: A sensitive and selective sensor for biothiols based on the recovered fluorescence of the CdTe quantum dots (QDs)-Hg(II) system is reported, which showed a high selectivity for Cys among the other 19 amino acids and succeeded in detecting biothsiols in the Hela cell.
Abstract: Herein, a sensitive and selective sensor for biothiols based on the recovered fluorescence of the CdTe quantum dots (QDs)-Hg(II) system is reported. Fluorescence of QDs could be quenched greatly by Hg(II). In the presence of biothiols, such as glutathione (GSH), homocysteine (Hcy), and cysteine (Cys), however, Hg(II) preferred to react with them to form the Hg(II)-S bond because of the strong affinity with the thiols of biothiols rather than quenching the fluorescence of the QDs. Thus, the fluorescence of CdTe QDs was recovered. The restoration ability followed the order GSH > Hcy > Cys due to the decreased steric hindrance effect. A good linear relationship was obtained from 0.6 to 20.0 micromol L(-1) for GSH and from 2.0 to 20.0 micromol L(-1) for Cys, respectively. The detection limits of GSH and Cys were 0.1 and 0.6 micromol L(-1), respectively. In addition, the method showed a high selectivity for Cys among the other 19 amino acids. Furthermore, it succeeded in detecting biothiols in the Hela cell.

Journal ArticleDOI
TL;DR: A series of salicylaldehyde azine derivatives were found to exhibit interesting aggregation-induced emission enhancement (AIEE) characteristics, and their in situ formation also promises potential applications in fluorescence sensing of hydrazine.
Abstract: A series of salicylaldehyde azine derivatives were found to exhibit interesting aggregation-induced emission enhancement (AIEE) characteristics. In good solvent, all these compounds displayed very weak fluorescence, while strong emission was observed when they were placed in poor solvent. Moreover, the AIEE color of these compounds varied from green to red depending on the substituents on azines. Their in situ formation also promises potential applications in fluorescence sensing of hydrazine.

Journal ArticleDOI
TL;DR: The interaction between malachite green and bovine serum albumin (BSA) under simulative physiological conditions was investigated by the methods of fluorescence spectroscopy, UV-vis absorption and circular dichroism (CD) spectroscope, which confirmed some micro-environmental and conformational changes of BSA molecules.

Journal ArticleDOI
Zengchen Liu1, Baodui Wang1, Zheng-yin Yang1, Yong Li1, Dong-Dong Qin1, Tianrong Li1 
TL;DR: Two novel 2-oxo-quinoline-3-carbaldehyde (4'-hydroxybenzoyl) hydrazone, thiosemicarbazone ligands and its corresponding Cu(2+) complexes were synthesized, and the two complexes' structures were determined by X-ray single crystal diffraction.

Journal ArticleDOI
Ming Wang1, Xinggui Gu1, Guanxin Zhang1, Deqing Zhang1, Daoben Zhu1 
TL;DR: This convenient and continuous fluorometric assay method for acetylcholinesterase and its inhibitor screening is successfully established with the ensemble of 1 and myristoylcholine and may extend to high-throughput screening of AChE inhibitors and relevant Alzheimer's disease (AD) drug discovery.
Abstract: A new convenient and continuous fluorometric assay method for acetylcholinesterase (AChE) and its inhibitor screening is successfully established with the ensemble of 1 [a TPE (tetraphenylethylene) compound with two sulfonate (-SO(3)(-)) units] and myristoylcholine (an amphiphilic compound as a good substrate of AChE). This new assay method is designed by making use of the aggregation-induced emission (AIE) feature of TPE compounds. Both dynamic light scattering (DLS) and fluorescence confocal microscopic measurements indicated the formation of aggregation complex for the ensemble of 1 and myristoylcholine and further disassembly of the aggregation complex after introducing AChE. The analysis for AChE can be carried out continuously, and AChE with concentration as low as 0.5 U/mL can be assayed. The results also clearly demonstrate the usefulness of this convenient assay method for kinetic study of AChE-catalyzed myristoylcholine hydrolysis and screening inhibitors of AChE. Given its simplicity and easy operation, this method may extend to high-throughput screening of AChE inhibitors and relevant Alzheimer's disease (AD) drug discovery.

Journal ArticleDOI
TL;DR: The results demonstrated that the fluorescence OFF-ON switching of this kind of thiol probe is due to the termination of the ICT effect, which quenches the emission, by a dark S(1) state) by cleavage of the 2,4-dinitrobenzenesulfonyl unit (as acceptor of I CT effect) with thiols, not the re-establishment of the D-pi-A feature of the fluorophore.
Abstract: Green and yellow-emitting 1,6- and 1,8-bis(phenylethynyl) pyrenes (dyes 7, 8, 9, and 10) with different intramolecular charge transfer (ICT) feature were synthesized and the effect of ICT on the photophysical properties of these derivatives were studied by UV−vis absorption spectra, fluorescence emission spectra, and DFT/TDDFT calculations. For the dyes with electron-pushing group (e.g., -dimethylamino, dye 8 and dye 10), structureless and solvent polarity-sensitive fluorescence emission spectra were observed. Conversely, dye with electron-withdrawing group (e.g., −CN, dye 7) shows structured and solvent polarity-independent emission spectra. OFF−ON fluorescent thiol probes 11 and 12 with 2,4-dinitrobenzenesulfonyl protected ethynylpyrene fluorophore were designed based on DFT/TDDFT calculations, which predicts dark state (S1) for these thiol probes (e.g., oscillator strength f = 0.0086 for S1←S0 transition of the probe 11). This dark state is induced by the ICT effect with ethynylated pyrene fluorophore ...

Journal ArticleDOI
TL;DR: This approach is expected to be extended to the detection of other biological molecules once the donor and acceptor nanoparticles are modified by proper molecules that can recognize the target biomolecules.
Abstract: Near-infrared (NIR) light can penetrate biological samples and even tissues without causing sample damage and avoid autofluorescence from biological samples in fluorescence detection. Thus, a luminescence resonance energy transfer (LRET)-based immunoassay that can be excited by NIR irradiation is a promising approach to the analysis of biological samples. Here we demonstrate the use of NIR-to-visible upconversion nanoparticles (UCNPs) as an energy donor, which can emit a visible light upon the NIR irradiation, and gold nanoparticles (Au NPs) as an energy acceptor, which can absorb the visible light emitted from the donor, to develop a sandwich-type LRET-based immunoassay for the detection of goat antihuman immunoglobulin G (IgG). Amino-functionalized NaYF(4):Yb, Er UCNPs and Au NPs were first prepared and then conjugated with the human IgG and rabbit antigoat IgG, respectively. The NIR-excited fluorescence emission band of human IgG-conjugated NaYF(4):Yb, Er UCNPs (lambda(max) = 542 nm) partially overlaps with the visible absorption band of the rabbit antigoat IgG-conjugated colloidal Au NPs (lambda(max) = 530 nm), satisfying the requirement of spectral overlap between donors and acceptors for LRET. A LRET system was then formed when goat antihuman IgG was added to a mixture of human IgG-modified NaYF(4):Yb, Er UCNPs (donor) and rabbit antigoat IgG-modified Au NPs (acceptor). The sandwich-type immunoreactions between the added goat antihuman IgG (primary antibody) and the two different proteins (antigen and secondary antibody on the surface of the donors and acceptors, respectively) cross-bridge the donors and acceptors and thus shorten their spacing, leading to the occurrence of LRET from UCNPs to Au NPs upon NIR irradiation. As a result, the quenching of the NIR-excited fluorescence of the UCNPs is linearly correlated to the concentration of the goat antihuman IgG (in the range of 3-67 microg x mL(-1)) present in the system, enabling the detection and quantification of the antibody. Such sandwich-type LRET-based approach can reach a very low detection limit of goat antihuman IgG (0.88 microg x mL(-1)), indicating that this method is applicable for the trace protein detection. This approach is expected to be extended to the detection of other biological molecules once the donor and acceptor nanoparticles are modified by proper molecules that can recognize the target biomolecules.

Journal ArticleDOI
TL;DR: The present IFE-based approach allows the design of fluorescent assays in a more simple, time-saving, and economical approach when compared with conventional metal NPs-based fluorescent Assays, since no modification step of the fluorophore was needed any more.
Abstract: We have demonstrated the design of a new type fluorescent assay based on the inner filter effect (IFE) of metal nanoparticles (NPs), which is conceptually different from the previously reported metal NPs-based fluorescent assays. With a high extinction coefficient and tunable plasmon absorption feature, metal NPs are expected to be capable of functioning as a powerful absorber to tune the emission of the fluorophore in the IFE-based fluorescent assays. In this work, we presented two proof-of-concept examples based on the IFE of Au NPs by choosing MDMO-PPV as a model fluorophore, whose fluorescence could be tuned by the absorbance of Au NPs with a much higher sensitivity than the corresponding absorbance approach. While the first assay worked in a turn-on mode upon the etching of Au NPs by the analyte, CN−, the second one functioned in a turn-off mode upon the catalytic growth of Au NPs by the analyte, H2O2. As a result, the present IFE-based approach can detect cyanide ranging from 1.0 × 10−6 to 6.0 × 10−...

Journal ArticleDOI
TL;DR: Nanotechnology provides a great opportunity to analytical chemists to develop better sensing strategies, but also relies on modern analytical techniques to pave its way to practical applications.
Abstract: Fluorescence-based detection is the most common method utilized in biosensing because of its high sensitivity, simplicity, and diversity. In the era of nanotechnology, nanomaterials are starting to replace traditional organic dyes as detection labels because they offer superior optical properties, such as brighter fluorescence, wider selections of excitation and emission wavelengths, higher photostability, etc. Their size- or shape-controllable optical characteristics also facilitate the selection of diverse probes for higher assay throughput. Furthermore, the nanostructure can provide a solid support for sensing assays with multiple probe molecules attached to each nanostructure, simplifying assay design and increasing the labeling ratio for higher sensitivity. The current review summarizes the applications of nanomaterials—including quantum dots, metal nanoparticles, and silica nanoparticles—in biosensing using detection techniques such as fluorescence, fluorescence resonance energy transfer (FRET), fluorescence lifetime measurement, and multiphoton microscopy. The advantages nanomaterials bring to the field of biosensing are discussed. The review also points out the importance of analytical separations in the preparation of nanomaterials with fine optical and physical properties for biosensing. In conclusion, nanotechnology provides a great opportunity to analytical chemists to develop better sensing strategies, but also relies on modern analytical techniques to pave its way to practical applications.

Journal ArticleDOI
TL;DR: In this paper, a gas-solid heterogeneous system for solar-chemical energy conversion of CO2-SCR with H2O on different nanostructure photocatalysts and the photocatalysis pathway were discussed.

Journal ArticleDOI
TL;DR: Finite-difference time-domain calculations are used to show that aluminum nanoparticles are efficient substrates for metal-enhanced fluorescence (MEF) in the ultraviolet (UV) for the label-free detection of biomolecules.
Abstract: We use finite-difference time-domain calculations to show that aluminum nanoparticles are efficient substrates for metal-enhanced fluorescence (MEF) in the ultraviolet (UV) for the label-free detection of biomolecules. The radiated power enhancement of the fluorophores in proximity to aluminum nanoparticles is strongly dependent on the nanoparticle size, fluorophore-nanoparticle spacing, and fluorophore orientation. Additionally, the enhancement is dramatically increased when the fluorophore is between two aluminum nanoparticles of a dimer. Finally, we present experimental evidence that functionalized forms of amino acids tryptophan and tyrosine exhibit MEF when spin-coated onto aluminum nanostructures.

Journal ArticleDOI
TL;DR: In this paper, a method based on quenching kinetics for the fluorescence of glutathione capped CdTe quantum dots (GSH-CdTe QDs) was developed for discriminating Fe2+ and Fe3+, and a GSH-cdte QDs-Fenton hybrid system was constructed for sensitive and selective determination of trace Fe2+.
Abstract: A method based on the quenching kinetics for the fluorescence of glutathione capped CdTe quantum dots (GSH-CdTe QDs) was developed for discriminating Fe2+ and Fe3+, and a GSH-CdTe QDs-Fenton hybrid system was constructed for sensitive and selective determination of trace Fe2+. Although both Fe2+ and Fe3+ could quench the fluorescence of GSH-CdTe QDs, the quenching kinetics was quite different for Fe2+ and Fe3+. The fluorescence of the GSH-CdTe QDs (30 nM) was quenched by about 18% in 1 min after the addition of Fe3+ (10 μM), and remained unchanged with further increase of reaction time. In contrast, the fluorescence intensity of the GSH-CdTe QDs decreased by about 65% in the first 5 min after the addition of Fe2+ (10 μM), then slowly decreased by 15% in the next 25 minutes. Other transition metal ions like Cu2+, Ni2+ and Co2+, Zn2+, and Mn2+ also gave very different quenching kinetics of the GSH-CdTe QDs from Fe2+. No significant effect of the capping agents (GSH, thioglycolic acid, and mercaptopropionic ...

Journal ArticleDOI
TL;DR: An acoustophoresis based separation chip that prepares diagnostic plasma from whole blood linked to a clinical application that has the capacity to sequentially remove enriched blood cells in multiple steps to yield high quality plasma of low cellular content is reported on.
Abstract: The generation of high quality plasma from whole blood is of major interest for many biomedical analyses and clinical diagnostic methods. However, it has proven to be a major challenge to make use of microfluidic separation devices to process fluids with high cell content, such as whole blood. Here, we report on an acoustophoresis based separation chip that prepares diagnostic plasma from whole blood linked to a clinical application. This acoustic separator has the capacity to sequentially remove enriched blood cells in multiple steps to yield high quality plasma of low cellular content. The generated plasma fulfills the standard requirements ( 0.99) in the generated plasma via fluorescence readout without any signal amplification at clinically relevant levels (0.19-21.8 ng/mL).

Journal ArticleDOI
15 May 2009-Talanta
TL;DR: The fluorescent enhancement, binding affinity, and detection limit of the peptide probe for HTM ions were described and were lower than the EPA's drinking water maximum contaminant levels (MCL).

Journal ArticleDOI
TL;DR: In this article, the authors have traced pharmacokinetics and biodistribution of each component of siRNA polyplexes formed with polyethylenimine 25 kDa (PEI) or PEGylated PEIs by in vivo real-time gamma camera recording, SPECT imaging, and scintillation counting of blood samples and dissected organs.

Journal ArticleDOI
TL;DR: The results of this study suggest that the use of conventional methods for analysis of SMP is not appropriate for investigation of membrane fouling in MBRs.

Journal ArticleDOI
TL;DR: The proposed analytical method offers a rapid and reproducible trace detection capability for mercury (II) ions in water by using droplet-based microfluidics combined with surface-enhanced Raman scattering (SERS) detection.
Abstract: We report a new method for the trace analysis of mercury (II) ions in water. The approach involves the use of droplet-based microfluidics combined with surface-enhanced Raman scattering (SERS) detection. This novel combination provides both fast and sensitive detection of mercury (II) ions in water. Specifically, mercury (II) ion detection is performed by using the strong affinity between gold nanoparticles and mercury (II) ions. This interaction causes a change in the SERS signal of the reporter molecule rhodamine B that is a function of mercury (II) ion concentration. To allow both reproducible and quantitative analysis, aqueous samples are encapsulated within nanoliter-sized droplets. Manipulation of such droplets through winding microchannels affords rapid and efficient mixing of the contents. Additionally, memory effects, caused by the precipitation of nanoparticle aggregates on channel walls, are removed since the aqueous droplets are completely isolated by a continuous oil phase. Quantitative analysis of mercury (II) ions was performed by calculating spectral peak area of rhodamine B at 1,647 cm−1. Using this approach, the calculated concentration limit of detection was estimated to be between 100 and 500 ppt. Compared with fluorescence-based methods for the trace analysis of mercury (II) ions, the detection sensitivities were enhanced by approximately one order of magnitude. The proposed analytical method offers a rapid and reproducible trace detection capability for mercury (II) ions in water.

Journal ArticleDOI
TL;DR: In this paper, the authors discuss the latest advances in technologies that record and assess spectrally-resolved fluorescence lifetime data as well as their biological and clinical applications, and show how these methods provide efficient sensing of molecules correlated with changes in the mitochondrial metabolic redox state in pathological conditions and/or of cell ultrastructures in diseased tissue, based on the presence of oxidation/reductionsensitive fluorophores and cell-specific chromophores.
Abstract: The study of biological systems in their real environmental conditions is crucial to decipher the true image of structures and processes underlying their functionality. In this regard, development of non-invasive optical techniques that do not require labelling, such as the investigation of tissue endogenous fluorescence, is particularly important and, as reflected in the increasing number of contributions published recently on this subject, was recognized by many leading groups. Multi-spectral and lifetime detection of fluorescence provides an effective experimental tool to discriminate between multiple naturally-occurring fluorophores in living tissues. At the same time, however, data analysis allowing us to understand the spectral, temporal and spatial information gathered, describing individual molecules involved in the autofluorescence of intact biological systems, represents a tough scientific challenge that has not yet been fully resolved. In this review, we discuss the latest advances in technologies that record and assess spectrally-resolved fluorescence lifetime data as well as their biological and clinical applications. We show how these methods provide efficient sensing of molecules correlated with changes in the mitochondrial metabolic redox state in pathological conditions and/or of cell ultrastructures in diseased tissue, based on the presence of oxidation/reductionsensitive fluorophores and/or cell-specific chromophores. Future directions are also outlined. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Journal ArticleDOI
TL;DR: The photophysical properties that make GFPs so special as pH indicators for in vivo use are discussed and the probes that are utilized most by the scientific community are described.
Abstract: Green fluorescent protein (GFP) and its variants have been used as fluorescent reporters in a variety of applications for monitoring dynamic processes in cells and organisms, including gene expression, protein localization, and intracellular dynamics GFP fluorescence is stable, species-independent, and can be monitored noninvasively in living cells by fluorescence microscopy, flow cytometry, or macroscopic imaging techniques Owing to the presence of a phenol group on the chromophore, most GFP variants display pH-sensitive absorption and fluorescence bands Such behavior has been exploited to genetically engineer encodable pH indicators for studies of pH regulation within specific intracellular compartments that cannot be probed using conventional pH-sensitive dyes These pH indicators contributed to shedding light on a number of cell functions for which intracellular pH is an important modulator In this review we discuss the photophysical properties that make GFPs so special as pH indicators for in vivo use and we describe the probes that are utilized most by the scientific community