BAVILI TABRIZI, Ahad y DEHGHANI TEYMURLOUIE, Nadereh. Application of Sodium Dodecyl Sulfate Coated Iron Oxide Magnetic Nanoparticles for the Extraction and Spectrofluorimetric Determination of Propranolol in Different Biological Samples. J. Mex. Chem. Soc [online]. 2016, vol.60, n.3, pp.108-116. ISSN 1870-249X.. A new analytical approach was developed involving magnetic solid-phase extraction (MSPE) and spectrofluorimetric determination of propranolol (PRO) in biological fluids. A urine or plasma sample was prepared and adjusted to pH 3-4, then PRO was quickly extracted using Fe3O4 magnetic nanoparticles (MNPs) modified by the surfactant sodium dodecyl sulfate (SDS) and determined applying spectrofluorimetry. Experimental conditions, such as the amount of MNPs and SDS, pH value, standing time, desorption solvent and maximal extraction volume have been adjusted to optimize the extraction process and to obtain analytical characteristics of the method. Linearity was observed in the analytes ...
TY - JOUR. T1 - Multispectral scanning time-resolved fluorescence spectroscopy (TRFS) technique for intravascular diagnosis. AU - Xie, Hongtao. AU - Bec, Julien. AU - Liu, Jing. AU - Sun, Yang. AU - Lam, Matthew. AU - Yankelevich, Diego R.. AU - Marcu, Laura. PY - 2012/7/1. Y1 - 2012/7/1. N2 - This study describes a scanning time-resolved fluorescence spectroscopy (TRFS) system designed to continuously acquire fluorescence emission and to reconstruct fluorescence lifetime images (FLIM) from a luminal surface by using a catheter-based optical probe with rotary joint and pull-back device. The ability of the system to temporally and spectrally resolve the fluorescence emission from tissue was validated using standard dyes and tissue phantoms (e.g., ex vivo pig aorta phantom). Current results demonstrate that this system is capable to reliably resolve the fluorescence emission of multiple fluorophores located in the lumen; and suggest its potential for intravascular detection of distinct biochemical ...
A rapid, simple and sensitive synchronous specrtofluorimetric method has been developed for the simultaneous analysis of binary mixture of metoprolol (MTP) and felodipine (FDP). The method is based upon measurement of the synchronous fluorescence intensity of the two drugs at Δλ of 70 nm in aqueous solution. The different experimental parameters affecting the synchronous fluorescence intensities of the two drugs were carefully studied and optimized. The fluorescence intensity-concentration plots were rectilinear over the ranges of 0.5-10 μg/mL and 0.2-2 μg/mL for MTP and FDP, respectively. The limits of detection were 0.11 and 0.02 μg/mL and quantification limits were 0.32 and 0.06 μg/mL for MTP and FDP, respectively. The proposed method was successfully applied for the determination of the two compounds in their commercial tablets and the results obtained were favorably compared to those obtained with a comparison method.
The paper reviewed the application these years of fluorescence spectrophotometry in environmental monitoring.The content includes the principle,the establishment of methods,the study of fluorescence system and the development of the combination with other techniques. It indicated that fluorescence method is sensitive, selective, less sample using and simple. It is an effective way for the analysis of trace elements and substances in complicated environmental samples. It will have a broad prospect in environmental analysis with the combination with other techniques.
TY - JOUR. T1 - Steady-state and time-resolved fluorescence spectroscopic studies on interaction of the N-terminal region with the hairpin loop of the phytocystain Scb. AU - Doi-Kawano, Keiko. AU - Nishimoto, Etsuko. AU - Kouzuma, Yoshiaki. AU - Takahashi, Daisuke. AU - Yamashita, Shoji. AU - Kimura, Makoto. PY - 2009/7/1. Y1 - 2009/7/1. N2 - The steady-state and time-resolved fluorescece spectroscopy is one of the most powerful method to detect and analyze subtle conformation change and interaction between peptide elements in protein. Phytocystatin Scb isolated from sunflower seeds includes a single Trp residue at position 85. In an attempt to investigate the interaction of the N-terminal region of Scb with the first and second hairpin loops by fluorescence spectroscopy of Trp residue, two Scb mutants in which single Trp locates at position 52 and 58, respectively, and their N-terminal removed mutants were generated. The N-terminal truncation changed the fluorescence decay kinetics of Trp52 ...
TY - JOUR. T1 - Fluorescence correlation spectroscopy of finite-sized particles. AU - Wu, Bin. AU - Chen, Yan. AU - Müller, Joachim D.. PY - 2008/4. Y1 - 2008/4. N2 - A theory is presented to study fluorescence correlation spectroscopy for particles with size comparable to the beam waist of the observation volume. Analytical correlation curves are derived for some experimentally interesting particle geometries. It is found that the finiteness of the particle generally decreases the value of the correlation amplitude and increases the correlation time compared to a point particle model. Furthermore, not only the size but also the distribution of fluorophores affects the shape of the correlation function. This is experimentally demonstrated with surface and internally labeled fluorescent spheres. In addition, experiments are performed on fluorescent spheres of different radii to validate the model by comparing the results to theoretical predictions.. AB - A theory is presented to study ...
TY - JOUR. T1 - Detection of Pentosidine Cross-Links in Cell-Secreted Decellularized Matrices Using Time Resolved Fluorescence Spectroscopy. AU - Mitra, Debika. AU - Fatakdawala, Hussain. AU - Nguyen-Truong, Michael. AU - Creecy, Amy. AU - Nyman, Jeffry. AU - Marcu, Laura. AU - Leach, Jonathan K. PY - 2017/9/11. Y1 - 2017/9/11. N2 - Hyperglycemia-mediated, nonenzymatic collagen cross-links such as pentosidine (PENT) can have deleterious effects on cellular interactions with the extracellular matrix (ECM). Present techniques to quantify PENT are limited, motivating the need for improved methods to study the accumulation and contribution of PENT toward diabetic clinical challenges such as impaired bone healing. Current methods for studying PENT are destructive, laborious, and frequently employ oversimplified collagen films that lack the complexity of the native ECM. The primary goal of this study was to evaluate the capacity of time-resolved fluorescence spectroscopy (TRFS) to detect PENT in ...
We compared various spectroscopic properties of a norfloxacin-single stranded DNA complex with those of norfloxacin-double stranded DNA complex. Norfloxacin binds to both double- and single stranded DNA, and we observed the following spectroscopic changes for both complexes: hypochromism in the norfloxacin absorption region in the absorption spectrum, the characteristic induced CD spectrum consisting of a weak positive band at 323 nm and a strong positive band at 280-300 nm followed by a negative band in the 260 nm region, a strong decrease in the fluorescence intensity and a red-shift in the fluorescence emission spectrum, and shorter fluorescence decay times. These results indicate that the environments of the bound norfloxacin in both DNAs are similar, although the equilibrium constant of the norfloxacin-single stranded DNA was twice as high as the norfloxacin-double stranded DNA complex. Both complexes were thermodynamically favored with similar negative ΔGo. Negative ΔHo terms contribute ...
Berland, K.M., So, P.T., Gratton, E. 1995. Two-photon fluorescence correlation spectroscopy: method and application to the intracellular environment. Biophys J. 68(2):694-701. PubMed. Chen Y, Müller JD, So PTC, Gratton E. 1999. The photon counting histogram in fluorescence fluctuation spectroscopy. Biophys J. 77: 553-567. PubMed. Elson EL. 2001. Fluorescence correlation spectroscopy measures molecular transport in cells. Traffic 2(11):789-96. PubMed. Elson EL, Magde D. 1974. Fluorescence correlation spectroscopy. I. Conceptual basis and theory. Biopolymers, 13(1):1-27. Kask P, Palo K, Ullmann D and Gall K. 1999. Fluorescence-intensity distribution analysis and its application in biomolecular detection technology. Proc Natl Acad Sci USA 96:13756-13761. PubMed Kis-Petikova K, Chen Y, Müeller JD, Gratton E. 2000. Application of scanning fluorescent correlation spectroscopy for determination of particle shape. Biophys. J., 78(1), 2603. Koppel DE, Axelrod D, Schlessinger J, Elson EL, Webb WW. 1976. ...
291309859 - EP 1259805 A1 2002-11-27 - LIPOPROTEIN ASSAY - [origin: WO0153829A1] A method of assaying to determine the identity and/or concentration or relative concentration in a sample solution of a particular one of a number of different target molecule types, comprise the steps of: i) adding to the sample a probe substance which binds to the or each target molecule type and which when so bound fluoresces under appropriate excitation; ii) performing a time-resolved fluorescence measurement on the sample; and iii) making said determination from analysis of the time decay data obtained from said time-resolved fluorescence measurement.[origin: WO0153829A1] A method of assaying to determine the identity and/or concentration or relative concentration in a sample solution of a particular one of a number of different target molecule types, comprise the steps of: i) adding to the sample a probe substance which binds to the or each target molecule type and which when so bound fluoresces under appropriate
The detailed analysis of the processes of electronic energy relaxation in a substance, taking place after the short optical impulses of excitation, shows that mathematical models of the detected optical intensity decay can not be expressed by a combination of elementary mathematical functions. In the present work we suggest the approach to the parameter estimation of the decay curves, obtained from the time-resolved fluorescence experiments, based on the computer simulation methods. By means of simulation elementary processes of energy relaxation can be reproduced with the highest level of the detailed elaboration. Given processes are characterized by a set of parameters which have to be estimated. For the estimation we tried several methods, which do not require calculation of the derivatives, as in widespread Marquardt algorithm, that could be difficult for the decay curves, represented by a simulation model. The main advantage of the proposed approach is that it is possible to estimate the ...
Article Three-dimensional excitation emission matrix fluorescence spectroscopy and gel-permeating chromatography to characterize extracellular polymeric substances in aerobic granulation. Three-dimensional excitation emission matrix (EEM) fluorescenc...
Steady State Spectrofluorometer from HORIBA Scientific. The FluoroLog-3, a modular instrument, is the Worlds Most Sensitive Spectrofluorometer
Fluorescence correlation spectroscopy (FCS) is a very useful tool for examining mobility and interactions in a variety of systems including membranes. FCS is highly sensitive to small differences in the diffusion rates of proteins and lipids, which allows for instance to characterize differences in phase behavior of lipid bilayers. FCS is used to analyze the binding of diffusible ligands to membrane receptors, such as membrane proteins or glycolipids. Changes in the fluorescence brightness parameter reveal membrane protein oligomerization. Moreover, the use of dual-color fluorescence cross-correlation (dcFCCS) allows to assess protein-protein binding in cases, where binding does not lead to significant changes in diffusion rates. The dual-color cross-correlation technique can also be employed to detect dynamic co-localization of labeled cargo molecules in small, mobile carriers, such as transport vesicles. Owing to the use of fluorescent labels, FCS is highly specific and can be applied both to ...
In flow cytometry, the fluorescence decay time of an excitable species has been largely underutilized and is not likely found as a standard parameter on any imaging cytometer, sorting, or analyzing system
Nanosecond time-resolved emission spectral techniques have been applied to the problem of the origin and nature of the well-known temperature-dependent spectral shifts characteristic of the aminophthalimides in alcohol solvents. It is demonstrated that the temperature-dependent spectral shifts are in fact due to time-dependent spectral shifts. At least two relaxation times characterize this phenomenon. One relaxation time is observed to be subnanosecond in character and may be associated with the exciplex that presumably is present in the system. The other relaxation time is presumably associated with the non-specific dipolar reorientation although it has distinctly different characteristics from the solvent dielectric relaxation time. Wavelength-dependent fluorescence decay that can be explained by the time dependence of the emission spectrum is also observed. (Author)(*IMIDES
Department of Biological Sciences, Texas Tech University, Lubbock 79409, USA. [email protected] The function of Lhca4, a gene encoding the photosystem 1 type IV chlorophyll a/b-binding protein complex in Arabidopsis, was investigated using antisense technology. Lhca4 protein was reduced in a number of mutant lines and abolished in one. The inhibition of protein was not correlated with the inhibition of mRNA. No depletion of Lhca1 was observed, but the low-temperature fluorescence emission spectrum was drastically altered in the mutants. The emission maximum was blue-shifted by 6 nm, showing that chlorophyll molecules bound to Lhca4 are responsible for most of the long-wavelength fluorescence emission. Some mutants also showed an unexplainable delay in flowering time and an increase in seed weight.. MeSH Terms ...
To understand the function of cellular protein networks, spatial and temporal context is essential. Fluorescence correlation spectroscopy (FCS) is a single-molecule method to study the abundance, mobility and interactions of fluorescence-labeled biomolecules in living cells. However, manual acquisition and analysis procedures have restricted live-cell FCS to short-term experiments of a few proteins. Here, we present high-throughput (HT)-FCS, which automates screening and time-lapse acquisition of FCS data at specific subcellular locations and subsequent data analysis. We demonstrate its utility by studying the dynamics of 53 nuclear proteins. We made 60,000 measurements in 10,000 living human cells, to obtain biophysical parameters that allowed us to classify proteins according to their chromatin binding and complex formation. We also analyzed the cell-cycle-dependent dynamics of the mitotic kinase complex Aurora B/INCENP and showed how a rise in Aurora concentration triggers two-step complex ...
Background: The accumulation of fibrillar deposits of amyloid beta-peptide (A beta) in brain parenchyma and cerebromeningeal blood vessels is a key step in the pathogenesis of Alzheimers disease. In this report, polymerization of A beta was studied using fluorescence correlation spectroscopy (FCS), a technique capable of detecting small molecules and large aggregates simultaneously in solution. Results: The polymerization of A beta dissolved in Tris-buffered saline, pH 7.4, occurred above a critical concentration of 50 mu M and proceeded from monomers/dimers into two discrete populations of large aggregates, without any detectable amount of oligomers. The aggregation showed very high cooperativity and reached a maximum after 40 min, followed by an increase in the amount of monomers/dimers and a decrease in the size of the large aggregates. Electron micrographs of samples prepared at the time for maximum aggregation showed a mixture of an amorphous network and short diffuse fibrils, whereas only ...
The retinoic acid receptor (RAR) is a member of the nuclear receptor superfamily. This ligand‐inducible transcription factor binds to DNA as a heterodimer with the retinoid X receptor (RXR) in the nucleus. The nucleus is a dynamic compartment and live‐cell imaging techniques make it possible to investigate transcription factor action in real‐time. We studied the diffusion of EGFP-RAR by fluorescence correlation spectroscopy (FCS) to uncover the molecular interactions determining receptor mobility. In the absence of ligand, we identified two distinct species with different mobilities. The fast component has a diffusion coefficient of D1 = 1.8−6.0 µm2/second corresponding to small oligomeric forms, whereas the slow component with D2 = 0.05−0.10 µm2/second corresponds to interactions of RAR with the chromatin or other large structures. The RAR ligand‐binding‐domain fragment also has a slow component, probably as a result of indirect DNA‐binding through RXR, with lower affinity ...
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We report a novel, compact and automated multidimensional spectrofluorometer that exploits a fibre-laser-pumped ultrafast supercontinuum source to provide resolution with respect to intensity, excitation and emission wavelength, decay time and polarisation. This instrument has been applied to study the photophysics of the phase-sensitive membrane probe di-4-ANEPPDHQ and to characterise protein-protein interactions via Förster resonance energy transfer. It can be applied to in situ measurements via a fibre-optic probe in medical and other contexts and is demonstrated here to provide a comprehensive characterisation of tissue autofluorescence.
We demonstrate a smartphone-integrated handheld detection instrument capable of utilizing the internal rear-facing camera as a high-resolution spectrometer for measuring the colorimetric absorption spectrum, fluorescence emission spectrum, and resonant reflection spectrum from a microfluidic cartridge insert
Rhodopsin self-associates in the plasma membrane. At low concentrations, the interactions are consistent with a monomer-dimer equilibrium (Comar et al., J Am Chem Soc 136(23):8342-8349, 2014). At high
Metallic nano-antennas provide strong field confinement and intensity enhancement in hotspots and thus can ultimately enhance fluorescence detection and provide ultra small detection volumes. In solution-based fluorescence measurements, the diffraction limited focus driving the nano-antenna can outshine the fluorescence originating from the hotspot and thus render the benefits of the hotspot negligible. We introduce a model to calculate the effect of a nano-antenna, or any other object creating a nontrivial intensity distribution, for fluorescence fluctuation measurements. Approximating the local field enhancement of the nano-antenna by a 3D Gaussian profile, we show which hotspot sizes and intensities are the most beneficial for an FCS measurement and compare it to realistic antenna parameters from literature.. © 2014 Optical Society of America. Full Article , PDF Article ...
Read independent reviews on NANOPHOX - Photon Cross-correlation Spectroscopy for size and stability analysis of nano-suspensions and emulsions from 1 nm to 10,000 nm from Sympatec GmbH on SelectScience
Transmembrane domains (TMD) connect the inner with the outer world of a living cell. Single TMD containing (bitopic) receptors are of particular interest, because their oligomerization seems to be a common activation mechanism in cell signaling. We analyzed the composition of TMDs in bitopic proteins within the proteomes of 12 model organisms. The average number of strongly polar and charged residues decreases during evolution, while the occurrence of a dimerization motif, GxxxG, remains unchanged. This may reflect the avoidance of unspecific binding within a growing receptor interaction network. In addition, we propose a new experimental approach for studying helix-helix interactions in giant plasma membrane vesicles using scanning fluorescence cross-correlation spectroscopy. Measuring eGFP/mRFP tagged versions of cytokine receptors confirms the homotypic interactions of the erythropoietin receptor in contrast to the Interleukin-4 receptor chains. As a proof of principle, by swapping the TMDs, ...
This invention relates to a diagnostic apparatus and particularly to an apparatus for the diagnosis of malignant tumor and the method of using the apparatus for diagnosis. The apparatus employs an ultraviolet light source with an emitting waveband of 3000A-4000A. Light from the light source is transmitted through a bundle of quartz optic fibers to the surface of the tumor, whether benign or malignant, to stimulate it, which then generates a specific intrinsic fluorescence spectrum. The intrinsic fluorescence spectrum reflected from the surface of the tumor is transmitted by a second bundles of glass fibers placed near it to a color resolution means, then processed by a scanning means and a circuit means, and displayed recorded by a display recording means. The display may be a graphic presentation of the intrinsic fluorescence spectrum of the tumor that is tested. If the graphic presentation displayed includes a single peak within the range of the blue color band, it indicates that the tumor being
Abstract A study of the photoluminescence excitation spectrum in a crystal of mercury diiodide is reported. Each of the two luminescence bands peaking at 543 and 572-575 nm investigated was found to have its own excitation spectrum. The excitation spectrum of the 575-nm line in the... mehr ...
Fast and non-invasive, diagnostic techniques based on fluorescence spectroscopy have the potential to link the biochemical and morphologic properties of tissues to individual patient care. One of the most widely explored applications of fluorescence spectroscopy is the detection of endoscopically invisible, early neoplastic growth in epithelial tissue sites. Currently, there are no effective diagnostic techniques for these early tissue transformations. If fluorescence spectroscopy can be applied successfully as a diagnostic technique in this clinical context, it may increase the potential for curative treatment, and thus, reduce complications and health care costs. Steady-state, fluorescence measurements from small tissue regions as well as relatively large tissue fields have been performed. To a much lesser extent, time-resolved, fluorescence measurements have also been explored for tissue characterization. Furthermore, sources of both intrinsic (endogenous fluorophores) and extrinsic ...
TY - JOUR. T1 - Highly photostable ketopyrrolyl-BODIPYs with red aggregation-induced emission characteristics for ultrafast wash-free mitochondria-targeted bioimaging. AU - Wu, Hao. AU - Guo, Xing. AU - Yu, Changjiang. AU - Wong, Wai Yeung. AU - Hao, Erhong. AU - Jiao, Lijuan. PY - 2020/5. Y1 - 2020/5. N2 - Subcellular organelle-specific probes, including mitochondria-targeted fluorescent probes, have attracted enormous research interests because they can monitor or visualize the morphology or biological activities of specific organelles and play an indispensable role in disease diagnosis. To follow the process, highly specific and photostable fluorescent probes are in demand. However, commercially available mitochondria probes normally suffer from poor photostability under laser irradiation and aggregation caused quenching (ACQ) in the aggregate state. In this work, two simple aggregation-induced emission(AIE)-active meso-2-ketopyrrolyl BODIPYs were developed via a convenient one-pot synthetic ...
There are various fluorescent probes such as ANS (anilinonapthalene 8-sulphonate) and N-methyl-2-anilino-6-naphthalene sulphonate (MNS). They both contain charged and hydrophobic areas and therefore are situated at the water-lipid interface of the membrane. The fluorescent properties of the molecule vary with its mobility and also with the polarity of the environment. Studies with the ANS probe has shown that structural changes occur in mitochondrial membrane during oxidative phosphorylation. These probes have also helped in giving information about the structural features of the plasma membrane. ...
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Single-molecule fluorescence spectroscopy and super-resolution microscopy are important elements of the ongoing technical revolution to reveal biochemical and cellular processes in unprecedented clarity and precision. Demands placed on the photophysical properties of the fluorophores are stringent a …
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 ...
Calcium ions play an important role in cell function, acting as effectors and/or signaling molecules for a variety of cellular biochemical and physiological processes. The development of a variety of Ca2+-sensitive fluorescent indicators and advancements in imaging technology have enhanced the ability to follow both global and localized changes in intracellular Ca2+ at ever improving temporal and spatial resolution. Ratiometric Ca2+ indicators like fura-2 permit the measurement of intracellular Ca2+ concentration (Grynkiewicz et al., 1985). But, they tend to have a limited dynamic range and a significant fluorescence background, which reduce their sensitivity to small local increases in Ca2+. On the other hand, certain nonratiometric Ca2+ indicators, such as fluo-3, although not able to give a dynamic direct read-out of the Ca2+ concentration, have very low fluorescence when not bound to Ca2+ and have a significant increase in fluorescence intensity upon binding Ca2+ (e.g., ∼200 times for ...
This thesis describes the development of sensitive and high-resolution fluorescence spectroscopic and microscopic techniques and their application to probe biomolecules and their interactions in solution, lipid membrane model systems and in cells. Paper I-IV are largely focused on methodological developments. In paper I, a new fluorescence method based on fluorescence correlation spectroscopy (FCS) for detecting single particles was realized, requiring no fluorescent labeling of the particles. The method can yield information both about the diffusion properties of the particles as well as about their volumes. In paper II, a modified fluorescence cross correlation spectroscopy procedure with well characterized instrumental calibration was developed and applied to study cis interactions between an inhibitory receptor and its Major Histocompatibility Complex class I ligand molecule, both within the same cellular membranes. The quantitative analysis brought new insights into the Nature killer cells ...
Some APC-Cy7 conjugates show changes in their emission spectra with prolonged exposure to paraformaldehyde. For instruments equipped with a 561 nm Yellow-Green laser, a 585/15 nm filter is recommended for detection. When making decisions about which fluorochromes to use in your experiments, youll want to know their relative emission spectra. APC (Allophycocyanin) spectrum - APC (Allophycocyanin) is ... excitation and emission wavelengths using the interactive Spectrum Viewer - A web application for viewing and comparing spectra of various fluorescent compounds. BV605 is a tandem fluorochrome that combines BD Horizon BV421 and an acceptor dye with emission at 605nm. APC-H7 conjugates provide greater stability in light and paraformaldehyde fixatives and have less spillover into the APC channel than APC-Cy7 conjugates. However, because of its peak emission at 667 nm, Alexa Fluor® 647 cannot be seen well by eye, and it cannot be excited optimally with a mercury lamp. BV650 is a tandem fluorochrome ...
The cell membrane is organized in to different structures and it has been difficult to visualize these structures since they are believed to possess sizes below the optical resolution limit. Hence the development of new tools probing the biophysical properties of membranes is necessary. Imaging FCS is one such tool which allows the measurement of mobility at contiguous locations on cell membranes of live cells by analyzing the autocorrelation functions. In this thesis, Imaging FCS is being extended to Imaging FCCS enabling one to calculate cross-correlations and to extract parameters from the same. The next part discusses methods to characterize organization of membranes. The last part describes the study of membrane proteins and anti-microbials carried out using Imaging FCS. Unlike single point FCS which yields only mobility, imaging FCS provides mobility and heterogeneity and proved to be a valuable biophysical tool to characterize the dynamics and organization of cell membranes ...
To enable not only long sequence read but also high throughput in a DNA sequencer, the single molecule sequencing method based on direct observation of processive DNA polymerization is very promising. In this method, only incorporated nucleotides labeled with fluorescent dye should be detected under high concentration of unreacted nucleotides. Enhanced local field produced by plasmonic nanostructure is very suitable for such application because of its small size of a few ten nanometers. We have fabricated platinum bowtie nanostructure arrays producing fluorescence enhancement and have evaluated the performance using two-photon photoluminescence and single molecule fluorescence measurements. To enable use of multicolor dye labeling, visible light excitation around 500 nm is preferable, so that gold well known as a plasmonic material cannot be used. We explored suitable materials comprehensively by electromagnetic simulation and consequently chose platinum. Observation of bright photoluminescence from Pt
The single-molecule spectroscopy group is engaged in the development of new methods of single-molecule fluorescence spectroscopy and related photon data analysis. By utilizing the developed methods, we investigate the complex behavior of biomolecular systems, such as proteins, nucleic acids, and lipid membranes. Through the integrated approach of laser spectroscopy, biophysical chemistry, and statistical data analysis, we pursue creating a new field of molecular science ...
PA-Mode Single Wavelength allows the detection and fusion of photoacoustic signals with detailed anatomical images. Using a tuneable near infrared laser, the subject is illuminated at the desired wavelength (680-970nm and 1200-2000nm*) in order to visualize chromophores such as hemoglobin, melanin, dyes and nanoparticles.
What is Fluorescence Spectroscopy? Fluorescence is a type of luminescence caused by photons exciting a molecule, raising it to an electronic excited state. Overview of what is fluorescence, what is a fluorescence spectrum, what materials exhibit fluorescence.
TY - JOUR. T1 - Radiative and non-radiative decays from the excited state of Ti3+ ions in oxide crystals. AU - Yamaga, M.. AU - Gao, Y.. AU - Rasheed, F.. AU - ODonnell, K. P.. AU - Henderson, B.. AU - Cockayne, B.. PY - 1990/11/1. Y1 - 1990/11/1. N2 - The fluorescence spectra of Ti3+ in Y3Al5O12 (YAG), Al2O3 (sapphire), YAlO3 (YAP) observed at 10 K are composed of zero-phonon lines accompanied by the broad vibronic sidebands. The temperature dependence of the fluorescence lifetime and of the total intensity of the broadband measured in YAG and Al2O3 indicate that the radiative decay times from the excited states are nearly constant in the range 10-300 K. This demonstrates that the broadband radiative emissions in Ti3+:YAG and Ti3+:Al2O3 are due to magnetic dipole transitions or to electric dipole transitions induced by static odd-parity distortion, respectively. The decrease of the fluorescence lifetime with increasing temperature in Ti3+:YAG and Ti3+:Al2O3 is due to non-radiative decay from ...
Quantifying Gene Expression and Regulation in Living Cells by Fluorescence Fluctuation Imaging2017-01-112017-01-11Department of Biochemistry and Molecular Biology , CSU200px200px ...
Fluorophores currently used as fluorescent probes offer sufficient permutations of wavelength range, Stokes shift and spectral bandwidth to meet requirements imposed by instrumentation (e.g., 488 nm excitation), while allowing flexibility in the design of multicolor labeling experiments. Our online Fluorescence SpectraViewer (www.invitrogen.com/handbook/spectraviewer) provides an interactive utility for evaluating these factors during the experimental design process (Using the Fluorescence SpectraViewer-Note 23.1). The fluorescence output of a given dye depends on the efficiency with which it absorbs and emits photons, and its ability to undergo repeated excitation/emission cycles. Absorption and emission efficiencies are most usefully quantified in terms of the molar extinction coefficient (EC) for absorption and the quantum yield (QY) for fluorescence. Both are constants under specific environmental conditions. The value of EC is specified at a single wavelength (usually the absorption ...
The research of biomolecular processes on the level of single molecules and in volume ranges equivalent to the size of a single bacterium is of immense importance, both in basic research and in industrial high-throughput screening. The combination of modern confocal optics, new fluorescent dyes, sensitive photomultipliers and improved data processing has revolutionised the technique of fluorescence correlation spectroscopy (FCS). Over the past few years this has led to its widespread application, and alongside the technological advances in hardware development, Greiner Bio-One worked hand-in-hand with customers and instrument suppliers to develop the glass bottom microplates. These better satisfy the requirements of fluorescence correlation spectroscopy with regard to optical clarity and deformation when compared to standard polystyrene plates ...
We have shown that cold perfusion of hearts generates reactive oxygen and nitrogen species (ROS/RNS). In this study, we determined 1) whether ROS scavenging only during cold perfusion before global ischemia improves mitochondrial and myocardial function, and 2) which ROS leads to compromised cardiac function during ischemia and reperfusion (I/R) injury. Using fluorescence spectrophotometry, we monitored redox balance (NADH and FAD), O(2)(*-) levels and mitochondrial Ca(2+) (m[Ca(2+)]) at the left ventricular wall in 120 guinea pig isolated hearts divided into control (Con), MnTBAP (a superoxide dismutase 2 mimetic), MnTBAP (M) + catalase (C) + glutathione (G) (MCG), C+G (CG), and N(G)-nitro-L-arginine methyl ester (L-NAME; a nitric oxide synthase inhibitor) groups. After an initial period of warm perfusion, hearts were treated with drugs before and after at 27 degrees C. Drugs were washed out before 2 h at 27 degrees C ischemia and 2 h at 37 degrees C reperfusion. We found that on reperfusion the MnTBAP
This review exposes the current poor understanding of the internal segmental chain dynamics of dendrimers in solution probed by monitoring the process of excimer formation between pyrene labels covalently attached to the chain ends of dendrimers. The review begins by covering the bases of fluorescence and the kinetics of pyrene excimer formation before describing a procedure based on the Model Free (MF) analysis that is used to analyze quantitatively the fluorescence decays acquired for dendrimers, the ends of which have been fully and covalently labeled with pyrene. Comparison of the various trends obtained by different research groups describing the efficiency of pyrene excimer formation with the generation number of dendrimers illustrates the lack of consensus between the few studies devoted to the topic. One possible reason for this disagreement might reside in the presence of minute amounts of unattached pyrene labels which act as potent fluorescent impurities and affect the analysis of the
TY - JOUR. T1 - Fluorescence correlation spectroscopy in surface plasmon coupled emission microscope. AU - Borejdo, J.. AU - Calander, N.. AU - Gryczynski, Z.. AU - Gryczynski, I.. PY - 2006. Y1 - 2006. N2 - Study of dynamics of single molecules by Fluorescence Correlation Spectroscopy (PCS) requires that the rate of photon detection per molecule be high, that the background be low, and that there be a large change in fluorescent signal associated with change in a position of a molecule. PCS applied to microscopic Surface Plasmon Coupled Emission (SPCE) suggests a powerful method to meet those requirements. In this method, the observational volume is made shallow by placing a sample on a thin metal film and illuminating it with the laser beam at Surface Plasmon Resonance (SPR) angle through high numerical aperture objective. The illuminating light excites surface plasmons in the metal film that produce an evanescent wave on the aqueous side of the interface. The thickness of the detection volume ...
Novel core-shell nanoparticles were prepared as encapsulating agents for fluorescent organic dyes. These particles protect the dyes from polar solvents, allowing their use in aqueous environments, such as biological systems. The nanoparticles were synthesized using a ternary surfactant system containing the dyes as templates, using octadecyltrimethoxysilane (OTMS) as a reactive surfactant. Silanol groups were formed by the hydrolysis and condensation of the OTMS methoxy groups, to act as anchoring points for the growth of a siloxane shell. The dyes used in this study are polarity and rigidity sensitive; as a consequence, the dyes emission was studied by steady state fluorescence (SSF) and fluorescent lifetime measurements. The data obtained showed the effects of the isolation of the dyes from the solvent. An increase in the viscosity, together with a decrease in the polarity of the encapsulation volume, produced changes in the emission maxima of the dyes, demonstrating that the dyes were effectively
© The Author(s). Published by IOP Publishing Ltd. Probing the diffusion of molecules has become a routine measurement across the life sciences, chemistry and physics. It provides valuable insights into reaction dynamics, oligomerisation, molecular (re-)organisation or cellular heterogeneities. Fluorescence correlation spectroscopy (FCS) is one of the widely applied techniques to determine diffusion dynamics in two and three dimensions. This technique relies on the temporal autocorrelation of intensity fluctuations but recording these fluctuations has thus far been limited by the detection electronics, which could not efficiently and accurately time-tag photons at high count rates. This has until now restricted the range of measurable dye concentrations, as well as the data quality of the FCS recordings, especially in combination with super-resolution stimulated emission depletion (STED) nanoscopy. Here, we investigate the applicability and reliability of (STED-)FCS at high photon count rates (average
Protein encapsulated gold nanoclusters have received much attention due to the possibility of using them as a non-toxic fluorescent probe or marker for biomedical applications, however one major disadvantage currently is their low brightness and quantum yield in comparison to currently used fluorescent markers. A method of increasing the fluorescence emission of Human Serum Albumin (HSA) encapsulated gold nanoclusters (AuNCs) via a Polyallylamide hydrochloride (PAH) coating is described. PAH molecules with a molecular weight of ~17,500 Da were found to enhance the fluorescence emission of HSA-AuNCs by 3-fold when the protein/polymer concentration ratio is 2:1 in solution. Interestingly, the fluorescence lifetime of the AuNCs was found to decrease while the native tryptophan (TRP) fluorescence lifetime also decreased during the fluorescence emission intensity enhancement caused by the PAH binding. Coinciding with the decrease in fluorescence lifetime, the zeta potential of the system was observed ...
During the past five decades, the use of X-ray analytical methods has increased in the areas of materials characterization and phase identification. The wide range of applicability of the X-ray fluorescence method has made it a technique employed in thousands of laboratories all over the world. Over the years, many techniques and procedures have been developed that greatly enhance the versatility of the method. The purpose of the X-ray clinic is to combine theoretical and practical application of X-ray fluorescence spectrometry ...
Laser-induced fluorescence emission contains information about both spectra and time, so the different shapes, intensities and fluorescent lifetimes of fluorescence emission spectra can be used to measure the categories and contents of fluorescent substances with high sensitivity and good selectivity. To measure the oil micro-contamination in water, we utilized femtosecond ultraviolet laser pulse (fs Laser: MaiTai, Spectra Physics, US) as driving source and gated enhanced type ICCD (Time-resolved Fluorescence Spectroscopy, Lavision, German) as detector. We carried through laser-induced fluorescence measurement on DaGang crude oils and machine oils, accomplished data processing, and analyzed the differences of shapes of fluorescence spectra and lifetimes between crude oil and refined oil ...
Using a confocal epi-illuminated microscope with a polarizing beam splitter and dual-channel detection of single-molecule fluorescence induced by pulsed laser excitation, a new application of the three-dimensional, real-time spectroscopic technique BIFL (burst integrated fluorescence lifetime) is introduced. BIFL allows simultaneous registration of fluorescence intensity, lifetime, and anisotropy. It is shown to be well-suited to identify the freely diffusing fluorescent molecule Rhodamine 123 and the Enhanced Yellow Fluorescent Protein via their characteristic fluorescence anisotropy using a time-resolved analysis. Furthermore, data analysis is discussed and rotational correlation times of single molecules are determined. Applications for multidimensional single-molecule identification are outlined.
The fluorescence properties of tryptophan residues are sensitive to the microenvironment of fluorophores in proteins. Therefore, fluorescence characteristics are widely used to study structural transitions in proteins. However, the decoding of the structural information from spectroscopic data is challenging. Here we present a review of approaches developed for the decomposition of multi-component protein tryptophan fluorescence spectra and correlation of these spectral parameters with protein structural properties.
1. The fluorescent ATP analogue 1,N6-etheno-ATP is a good substrate and an efficient allosteric inhibitor of rabbit skeletal-muscle phosphofructokinase. 2. Fluorescence energy transfer occurs between bound 1,N6-etheno-ATP and phosphofructokinase. 1,N6-Etheno-ATP fluorescence is enhanced, intrinsic protein fluorescence is quenched, and the excitation spectrum of 1,N6-etheno-ATP fluorescence is characteristic of protein absorption. 3. The binding reaction of 1,N6-etheno-ATP observed by stopped-flow fluorimetry is biphasic. The fast phase results from binding to the catalytic site alone. The slow phase results from the allosteric transition of the R conformation into the T conformation induced by the binding of 1,N6-etheno-ATP to the regulatory site. 4. The fluorescence signal that allows the transition of the R conformation into the T conformation to be observed does not arise from 1,N6-etheno-ATP bound to the regulatory site. It arises instead from 1,N6-etheno-ATP bound to the catalytic site as a ...
The ethanol-water mixtures can emit fluorescence when excited by the ultraviolet (UV) light, which is different from pure ethanol and water. There are three emission bands of the mixtures and the center bands are located at 290, 305, and 330 nm, respectively. The fluorescence lifetimes of different emission bands are tested respectively: the average lifetime of 330-nm fluorescence band is about 26.5 ns, for the 305-nm emission band 2.5 ns, and for the 290-nm band 11 ns. By the spectral characteristic and the time-resolved spectroscopy one can conclude that there are several components in the solution of ethanol-water mixture. © 2005 Chinese Optics Letters. PDF Article ...
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TY - JOUR. T1 - Nanosecond fluorescence resonance energy transfer-fluorescence lifetime imaging microscopy to localize the protein interactions in a single living cell. AU - Elangovan, M.. AU - Day, R. N.. AU - Periasamy, A.. PY - 2002/2/18. Y1 - 2002/2/18. N2 - Visualizing and quantifying protein-protein interactions is a recent trend in biomedical imaging. The current advances in fluorescence microscopy, coupled with the development of new fluorescent probes such as green fluorescent proteins, allow fluorescence resonance energy transfer (FRET) to be used to study protein interactions in living specimens. Intensity-based FRET microscopy is limited by spectral bleed-through and fluorophore concentration. Fluorescence lifetime imaging (FLIM) microscopy and lifetime measurements are independent of change in fluorophore concentration or excitation intensity, and the combination of FRET and FLIM provides high spatial (nanometre) and temporal (nanoseconds) resolution. Because only the donor ...
In this work, fluorescence correlation spectroscopy (FCS) was used to investigate the effects of potassium iodide (KI) on the electronic-state population kinetics of a range of organic dyes in the visible wavelength range. Apart from a heavy atom effect promoting intersystem crossing to the triplet states in all dyes, KI was also found to enhance the triplet-state decay rate by a charge-coupled deactivation. This deactivation was only found for dyes with excitation maximum in the blue range, not for those with excitation maxima at wavelengths in the green range or longer. Consequently, under excitation conditions sufficient for triplet state formation, KI can promote the triplet state buildup of one dye and reduce it for another, red-shifted dye. This anticorrelated, spectrally separable response of two different dyes to the presence of one and the same agent may provide a useful readout for biomolecular interaction and microenvironmental monitoring studies. In contrast to the typical notion of ...
Sterile α motif (SAM) domains are found in many different proteins and shown to play important roles in various biological processes. The N-terminal domain of deleted in liver cancer 1 (DLC1) protein is a SAM domain which exists in a monomeric form in aqueous solution and facilitates the distribution of EF1A1 to the membrane periphery and ruffles upon growth factor stimulation. Here, we report the structure of an N-terminal truncated DLC1 SAM domain (DLC1-SAM) and its urea-induced equilibrium unfolding investigated with various biophysical methods such as CD, fluorescence emission spectroscopy, and NMR. CD and tryptophan intrinsic fluorescence emission data imply that the unfolding of DLC1-SAM follows a simple two-state mechanism, yet the NMR data suggest the presence of at least one intermediate state. The intermediate cannot be detected by NMR, but it does not exist in large aggregates as shown by analytical ultracentrifugation experiments. Analysis of the free energy values for different ...
TY - JOUR. T1 - Stark effects in gas-phase electronic spectra. Dipole moment of aniline in its excited S1 state. AU - Korter, T. M.. AU - Borst, D. R.. AU - Butler, C. J.. AU - Pratt, D. W.. PY - 2001/1/10. Y1 - 2001/1/10. N2 - Measurements of the Stark effect on the rotationally resolved S1←S0 fluorescence excitation spectrum of aniline are reported, providing quantitative information about the degree of charge transfer in the electronic transition. We find that μa(S1 = 2.801 ± 0.007 D, a value that is ∼150% larger than the ground state, μa(S0) = 1.129 ± 0.005 D. The enhanced value of the dipole moment in the S1 state is attributed to more efficient electron donation by the quasi-planar amino group to the aromatic ring.. AB - Measurements of the Stark effect on the rotationally resolved S1←S0 fluorescence excitation spectrum of aniline are reported, providing quantitative information about the degree of charge transfer in the electronic transition. We find that μa(S1 = 2.801 ± 0.007 ...
ortho-Aminobenzoic acid (Abz) has been used as a convenient fluorescent donor group in internally quenched fluorescent peptides, which are employed as substrates for several proteolytic enzymes. As Abz is usually bound to the N-amino terminal of these peptides, it is of interest to investigate the Abz group fluorescent properties bound to different amino acids. We report in this article the optical absorption and fluorescent properties, in aqueous media, of Abz bound to the alpha-amino group of Ala, Gly, Leu, ne, Val, Pro, Phe, Arg, Glu, Met, Asn, Tyr, and Trp, with monomethyl-amidated alpha-carboxyl group, in order to explore the origin of the drastic reduction of Abz attached to N-alpha amino group of prolyl-peptides, we also examined the fluorescence properties of Abz-NHCH3, Abz-N(CH3)(2), and Abz-pyrrolidine. Molecular dynamics simulation and NMR data indicated a lack of periplanarity of the Abz-dimethylamide, which could be the origin of low fluorescence quantum yield of ...
Fluorescence spectroscopy is spectroscopy which is based on the analysis of fluorescence light. It can be used in fields like chemistry, medicine and pharmacy, biomedical research and environmental monitoring.
Tryptophan fluorescence quenching is a type of fluorescence spectroscopy used for binding assays. The assay relies on the ability to quench the intrinsic fluorescence of tryptophan residues within a protein that results from changes in the local environment polarity experienced by the tryptophan(s) upon the addition of a binding partner or ligand. The quenching can arise from local changes near the interaction site or from binding-induced conformational changes. In cases where the titrant absorbs at or near the excitation or emission wavelengths of tryptophan, significant quenching can occur even without an interaction. This is known as the inner filter effect. This protocol describes how to use tryptophan fluorescence quenching to investigate the binding affinity of a protein for its partner/ligand and how to check and correct for the inner filter effect. As an example, we measured the binding affinity of the haem-binding protein, HusA, from Porphyromonas gingivalis for haem, and showed how we
Nowadays, emission regulations and the requirement to reduce greenhouse gas emissions have escalated engine development efforts. In the present work, the effect of compression ratio on the performance, combustion and emission characteristics of a spark-ignition engine is evaluated at different opera
合成系列含缩醛的双链正离子类脂分子,并用荧光光谱研究其与牛血清蛋白(BSA)的相互作用.通过荧光的变化,解释蛋白质构象的变化.在低类脂浓度时,少量类脂分子束缚在牛血清蛋白周围,荧光有很大幅度的淬灭,蛋白质本身肽链被解开,与此同时最大发射波长从(344±1) nm 蓝移到(331±1) nm.由于疏水相互作用,更多类脂分子不断地聚集在蛋白质周围,牛血清蛋白中的两个色氨酸残基被完全地包裹在类脂分子形成的双分子膜中,荧光强度不断增加直到恒定不变.;Interactions of a series of dialkyl cationic lipids linking with bovine serum albumin (BSA) through acetal (linker) have been studied by the fluorescence spectroscopy. At low concentrations of cationic lipids, the fluorescence intensity of BSA decreased with binding of cationic lipid, and the maximum of emission wavelength shifted from (344±1)nm to (331±1)nm. It indicates that the BSA goes to uncoiled flexible
PAN, Xiangliang et al. A comparison of five extraction methods for extracellular polymeric substances (EPS) from biofilm by using three-dimensional excitation-emission matrix (3DEEM) fluorescence spectroscopy. Water SA [online]. 2010, vol.36, n.1, pp.111-116. ISSN 1816-7950.. Two physical methods (centrifugation and ultrasonication) and 3 chemical methods (extraction with EDTA, extraction with formaldehyde, and extraction with formaldehyde plus NaOH) for extraction of EPS from alga-bacteria biofilm were assessed. Pretreatment with ultrasound at low intensity doubled the EPS yield without significant modification of the composition of EPS. Extraction with EDTA or extraction with formaldehyde plus NaOH increased yield by about 1 order of magnitude compared with other methods. However, the protein and polysaccharide content in EPS prepared with EDTA or formaldehyde plus NaOH were low. Two fluorescence peaks belonging to protein-like peaks and 2 fluorescence peaks belonging to humic acid-like ...
article{744458, author = {Remaut, Katrien and Sanders, Niek and De Geest, Bruno and Braeckmans, Kevin and Demeester, Jo and De Smedt, Stefaan}, issn = {0927-796X}, journal = {MATERIALS SCIENCE \& ENGINEERING R-REPORTS}, keyword = {SINGLE-PARTICLE TRACKING,FLUORESCENCE CORRELATION SPECTROSCOPY,CROSS-CORRELATION SPECTROSCOPY,advanced light microscopy,nuclear uptake,endocytosis,extracellular matrix,non-viral carriers,gene therapy,GLYCOL-POLYETHYLENIMINE/DNA COMPLEXES,CYSTIC-FIBROSIS SPUTUM,BLOCK-COPOLYMER MICELLES,RESONANCE ENERGY-TRANSFER,CAVEOLAE-MEDIATED ENDOCYTOSIS,INTRAVENOUS GENE DELIVERY,IMAGE CORRELATION SPECTROSCOPY}, language = {eng}, pages = {117--161}, title = {Nucleic acid delivery: Where material sciences and bio-sciences meet}, url = {http://dx.doi.org/10.1016/j.mser.2007.06.001}, volume = {58}, year = {2007 ...
A membrane-based assay device for detecting the presence or quantity of an analyte residing in a test sample is provided. The device utilizes time-resolved fluorescence to detect the signals generated by excited fluorescent labels. Because the labels can have relatively long emission lifetime, short-lived background interference can be practically eliminated through delayed fluorescence detection. In addition, the resulting fluorescent reader can have a simple and inexpensive design. For instance, in one embodiment, the reader can utilize a silicon photodiode and a pulsed light-emitting diode (LED) to accurately excite labels and detect fluorescence on a membrane-based assay device without requiring the use of expensive components, such as monochromators or narrow emission band width optical filters.
Current far-field fluorescence nanoscopes provide subdiffraction resolution by exploiting a mechanism of fluorescence inhibition. This mechanism is implemented such that features closer than the diffraction limit emit separately when simultaneously exposed to excitation light. A basic mechanism for such transient fluorescence inhibition is the depletion of the fluorophore ground state by transferring it (via a triplet) in a dark state, a mechanism which is workable in most standard dyes. Here we show that microscopy based on ground state depletion followed by individual molecule return (GSDIM) can effectively provide multicolor diffraction-unlimited resolution imaging of immunolabeled fixed and SNAP-tag labeled living cells. Implemented with standard labeling techniques, GSDIM is demonstrated to separate up to four different conventional fluorophores using just two detection channels and a single laser line. The method can be expanded to even more colors by choosing optimized dichroic mirrors and
Protein-RNA and protein-protein interactions involved in the assembly of the signal recognition particle (SRP) were examined using fluorescence spectroscopy. Fluorescein was covalently attached to the 3′-terminal ribose of SRP RNA following periodate oxidation, and the resulting SRP RNA-Fl was reconstituted into a fluorescent SRP species that was functional in promoting translocation of secretory proteins across the membrane of the endoplasmic reticulum. Each of the two protein heterodimers purified from SRP elicited a substantial change in fluorescein emission upon association with the modified RNA. The binding of SRP9/14 to singly-labeled SRP RNA-Fl increased fluorescein emission intensity by 41% at pH 7.5 and decreased its anisotropy from 0.18 to 0.16. The binding of SRP68/72 increased the fluorescein anisotropy from 0.18 to 0.23 but did not alter the emission intensity of SRP RNA-Fl. These fluorescence changes did not result from a direct interaction between the dye and protein because the ...
A new branch of fluorescence has emerged with the use of metallic nanostructures to enhance optical signals: Plasmon enhanced fluorescence (PEF). In the literature it has grown with two different names: surface enhanced fluorescence (SEF) and also metal enhanced fluorescence (MEF). In this thesis, we have explored some of the peculiar properties of plasmon enhanced fluorescence. In particular, we try to relate intrinsic molecular properties of fluorescence such as cross section and quantum yield to the enhanced signal. The source and basic properties of localized surface plasmon resonances is also discussed. The attention is then centre in the plasmon signature on the fluorescence spectrum or spectral profile modification. The matching of plasmon scattering and fluorescence emission assists in constructing fluorophore-nanoparticle systems for PEF applications. Specific experiments are discussed design to test the impact of the fluorophore quantum yield in observed enhancement. Finally, a practical
We use all-atom MD simulations, combined with patch-clamp electrophysiology and time-resolved fluorescence spectroscopy, to investigate functional dynamics of neurotransmitter transporters and Cl- channels. We developed kinetic state models to explain the functional coupling of secondary active glutamate transport and channel-like anion conduction in EAAT glutamate transporters (1-3), and advanced noise analysis techniques to measure unitary properties of transporter-associated channels (4). Using stopped-flow fluorescence recordings, we identified an induced-fit substrate binding mechanism in EAATs (4). The prokaryotic EAAT homolog GltPh is the founding member of the group of transporters with an elevator transport mechanism, and we used essential dynamics sampling to simulate the inward-outward transition path (5). We identified the Cl- permeation pathway and Cl- conduction mechanism in EAATs (5,6) using Computational Electrophysiology, a simulation technique for all-atom MD simulations of ...
7-AAD Staining Solution is a ready-to-use reagent suitable for the evaluation of cell viability in mono- or multiparametric analyses of human peripheral blood using flow cytometry.7-AAD (7-amino-actinomycin D) is a fluorescent dye that intercalates into double-stranded DNA (GC rich regions). It is excluded from viable cells, but can penetrate cell membranes of dead or dying cells. Therefore, it can be used instead of propidium iodide (PI) for the evaluation of cell death and apoptosis.The fluorescence emission maximum for 7-AAD is at 647 nm. When excited at 488 nm, 7-AAD is detected in the red fluorescence channel commonly used for R-phycoerythrin (PE)-Cy®5 tandem dye detection, with minimal spectral overlap into the yellow fluorescence channel commonly used for PE detection. - Nederland
7-AAD Staining Solution is a ready-to-use reagent suitable for the evaluation of cell viability in mono- or multiparametric analyses of human peripheral blood using flow cytometry. 7-AAD (7-amino-actinomycin D) is a fluorescent dye that intercalates into double-stranded DNA (GC rich regions). It is excluded from viable cells, but can penetrate cell membranes of dead or dying cells. Therefore, it can be used instead of propidium iodide (PI) for the evaluation of cell death and apoptosis. The fluorescence emission maximum for 7-AAD is at 647 nm. When excited at 488 nm, 7-AAD is detected in the red fluorescence channel commonly used for R-phycoerythrin (PE)-Cy® 5 tandem dye detection, with minimal spectral overlap into the yellow fluorescence channel commonly used for PE detection. - Schweiz
Nine novel 2-aryl-6-(aryleneethynylene)-1H-indoles were prepared by one pot Sonogashira cross-coupling in DMSO and fluoride promoted cyclization followed by N-alkylation. The photophysical properties of these compounds are described. Absorption and excitation spectra of these compounds were independent of the solvent polarity, while their emission spectra showed a pronounced dependence. Fluorescence quantum yields in solution were very high and decreased with solvent polarity; possible processes that account for excessive values of ? are discussed. Cyclic voltammetry studies indicate irreversible redox processes and DFT calculations suggest they occur in the indole segment. ...
Thawing permafrost due to increasingly warm temperatures in northern subarctic regions is releasing mercury. The consequent formation of thaw ponds in the peatland palsa valley of the Sasapimakwananisikw (SAS) river in Whapmagoostui-Kuujjuarapik, Québec may provide a pool for MMHg formation and a potential risk to aquatic and human life, if these ponds facilitate MMHg export through hydrological connections to nearby waterways. Hg methylation and MMHg demethylation activities were examined in thaw pond sediments using a Hg tracer isotope incubation experiment. Analysis by coupling gas chromatography cold-vapor atomic fluorescence spectrophotometry (GC-CVAFS) with inductively coupled mass spectrometry (ICP-MS) techniques showed that MMHg was produced at a higher rate and within the first 2 h of incubation for both summer and winter seasons. For thaw ponds SAS1A, SAS1B and SAS2A, MMHg was formed at 0.0048 % h-1, 0.0012 % h-1, and 0.0008 % h-1, respectively during winter and at 0.0001 % h-1, ...
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Fluorescence techniques are being used and applied increasingly in academics and industry. The Principles of Fluorescence Techniques course will outline the basic concepts of fluorescence techniques and the successful utilization of the currently available commercial instrumentation.. The course is designed for students who utilize fluorescence techniques and instrumentation and for researchers and industrial scientists who wish to deepen their knowledge of fluorescence applications. Key scientists in the field will deliver theoretical lectures. The lectures will be complemented by the direct utilization of steady-state and lifetime fluorescence instrumentation and confocal microscopy for FLIM and FFS applications.. Participants are recommended to have at least a bachelors degree in the life sciences, physical sciences or engineering before attending. Interactions between participants and lecturers will be fostered. Students will have ample opportunity to personally explain their research ...
Fluorescence techniques are being used and applied increasingly in academics and industry. The Principles of Fluorescence Techniques course will outline the basic concepts of fluorescence techniques and the successful utilization of the currently available commercial instrumentation.. The course is designed for students who utilize fluorescence techniques and instrumentation and for researchers and industrial scientists who wish to deepen their knowledge of fluorescence applications. Key scientists in the field will deliver theoretical lectures. The lectures will be complemented by the direct utilization of steady-state and lifetime fluorescence instrumentation and confocal microscopy for FLIM and FFS applications.. Participants are recommended to have at least a bachelors degree in the life sciences, physical sciences or engineering before attending. Interactions between participants and lecturers will be fostered. Students will have ample opportunity to personally explain their research ...
Vulnerable plaques, which are responsible for most acute ischemic events, are presently invisible to x-ray angiography. Their primary morphological features include a thin or ulcerated fibrous cap, a large necrotic core, superficial foam cells, and intraplaque hemorrhage. We present evidence that multimodal spectroscopy (MMS), a novel method that combines diffuse reflectance spectroscopy (DRS), intrinsic fluorescence spectroscopy (IFS), and Raman spectroscopy (RS), can detect these markers of plaque vulnerability. To test this concept, we perform an MMS feasibility study on 17 human carotid artery specimens. Following the acquisition of spectra, each specimen is histologically evaluated. Two parameters from DRS, hemoglobin concentration and a scattering parameter, are used to detect intraplaque hemorrhage and foam cells; an IFS parameter that relates to the amount of collagen in the topmost layers of the tissue is used to detect the presence of a thin fibrous cap; and an RS parameter related to ...
While this paper had no mention of wetting, surfaces, or capillary forces, the technique of fluorescence correlation spectroscopy is probably worth mentioning, as it is employed specifically in soft matter experiments. FCS is typically used to measure diffusion constants of fluorescent molecules in solution. The number of fluorescent molecules in the focal spot will follow a Poisson distribution, and the relative change in fluorescence over time with therefore vary both with the number of fluorescent particles (which determines the amplitude of the autocorrelation function) and the rate of diffusion of these particles (which determines the decay rate in the autocorrelation function). So if particles diffuse more slowly, then the fluorescence changes more slowly, and the correlation in fluorescence will apply over longer periods of time. The authors apply this principle of FCS to a two-state system: the MS2-GFP protein, where MS2 is the domain that will bind to a specific RNA target, and GFP is ...
Rapid activation of guanine nucleotide-binding protein (G protein)-mediated signal transduction mechanisms occurs in many tissues. The human neutrophil provides a useful model for studying the mechanisms of these fast processes. Fluorescent chemotactic tetrapeptide and pentapeptide exhibit 30-50% quenching of fluorescence upon binding to the neutrophil formyl peptide receptor, and their binding affinity is strongly regulated by the G protein Gi. We used rapid kinetic spectrofluorometric methods to study the assembly and disassembly of the ternary complex of ligand, receptor, and G protein in digitonin-permeabilized human neutrophils. Binding was studied up to 20 nM ligand, where the half-time for association was 1.2 sec. The rate constant of association was near that for diffusion-limited reactions of ligands and proteins, 2 x 10(7) M-1 sec-1. The rate of uncoupling of formyl peptide receptor from G protein in the presence of high concentrations of guanine nucleotide was , or = 5 sec-1 (i.e., ...
We report the use of the macrocyclic host cucurbit[7]uril (CB7) as a supramolecular additive in nanosecond time-resolved fluorescence (Nano-TRF) assays for proteases to enhance the discrimination of substrates and products and, thereby, the sensitivity. A peptide substrate was labeled with 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) as a long-lived (>300 ns) fluorescent probe and 3-nitrotyrosine was established as a non-fluorescent fluorescence resonance energy transfer (FRET) acceptor that acts as a
Correlation Spectroscopy is an increasingly popular method of analyzing spectral data, with the goal of improved understanding of sample chemistry, physics and spectroscopy. The original form of this method dealt exclusively with cases where a single sample is analyzed spectroscopically while being perturbed mechanically in a sinusoidal manner. However, more recent extensions towards spectroscopic data that is collected in the presence of any sample perturbation led to the concept of Generalized 2D Correlation Spectroscopy, which is the subject of this course.. The course will begin with an explanation of the principles of classical Correlation Spectroscopy. This will include a discussion of the two complementary methods to display the temporal correlation behavior in spectral data sets: the synchronous and asynchronous maps.. Several chemometric methods can be particularly useful when combined with Correlation Spectroscopy, including Self-Modeling Curve Resolution (a series of methods ...
Rothwell, P. J.; Berger, S.; Kensch, O.; Felekyan, S.; Antonik, M.; Woehrl, B. M.; Restle, T.; Goody, R. S.; Seidel, C.: Multiparameter single-molecule fluorescence spectroscopy reveals heterogeneity of HIV-1 reverse transcriptase: primer/template complexes. Proceedings of the National Academy of Sciences of the United States of America 100 (4), S. 1655 - 1660 (2003 ...
The nuclei of embryonic Swiss mouse fibroblasts in culture were targeted with the nucleic acid probe DAPI, which has an excitation maximum at 358 nanometers and an emission maximum at 461 nanometers when bound to DNA in cell cultures and tissue sections.
Because one of the main bottlenecks in determining the structure of protein molecules is producing good isolated single crystals, improved crystallization techniques would be useful in a wide range of genomics and pharmaceutical research.. Research reported in The Journal of Chemical Physics uses fluorescence correlation spectroscopy (FCS) to investigate the processes at the surface of a growing crystal. By focusing a laser on the crystal surface and measuring the resulting fluorescence, FCS can resolve dimensions as small as a single wavelength of the light.. Another advantage of fluorescence is that it provides a high signal-to-noise ratio, says author Shinpei Tanaka of Hiroshima University in Japan. We are able to measure very dilute solutions at the crystal interface.. The researchers found that when single tetragonal crystals of egg-white lysozyme formed, there was no concentration gradient between the solution and the crystal surface. However, in formation of clumps of needle-like ...
This thesis proposes mechanisms by which a spiked mobile phase fluorescence detector (SMP-FD) for HPLC is able to detect not only fluorescent compounds, but non-fluorescent chromophoric and non-fluorescent, non-chromophoric compounds as well. This reconfigured fluorescent detector is achieved simply.... Full description. ...
This thesis proposes mechanisms by which a spiked mobile phase fluorescence detector (SMP-FD) for HPLC is able to detect not only fluorescent compounds, but non-fluorescent chromophoric and non-fluorescent, non-chromophoric compounds as well. This reconfigured fluorescent detector is achieved simply.... Full description. ...
Oligomerization of membrane proteins has received intense research interest because of their importance in cellular signaling and the large pharmacological and clinical potential this offers. Fluorescence imaging methods are emerging as a valid tool to quantify membrane protein oligomerization at high spatial and temporal resolution. Here, we provide a detailed protocol for an image-based method to determine the number and oligomerization state of fluorescently labeled prototypical G-protein-coupled receptors (GPCRs) on the basis of small out-of-equilibrium fluctuations in fluorescence (i.e., molecular brightness) in single cells. The protocol provides a step-by-step procedure that includes instructions for (i) a flexible labeling strategy for the protein of interest (using fluorescent proteins, small self-labeling tags or bio-orthogonal labeling) and the appropriate controls, (ii) performing temporal and spatial brightness image acquisition on a confocal microscope and (iii) analyzing and ...
Fluorescence reading or fluorescence measurement is the measurement of the light rays coming out of the fluorescent particle by energizing through the light at much greater energy and comparatively much lesser wavelength. In this process, a sample is energized through the light generated using a source of light and then screened at a certain wavelength, either using a screener or monochromator.. The samples post being energized mostly radiate the lights at minimal energy and greater wavelength in comparison with the energized light and fluorescence within no time after energizing. The light post emission is screened, captured, and measured as well using detectors. Fluorescence reader comes handy in such occasions.. Energy emission mechanism. Great to see is the way the fluorescence has developed in terms of its standard in the past twenty years. This has made the intensity calculation of fluorescence a highly acclaimed method of fluorescence reader. Making things even more encouraging, there are ...
TY - JOUR. T1 - Synthesis and characterization of membrane stable bis(arylimino)isoindole dyes and their potential application in nano-biotechnology. AU - Kim, Benjamin. AU - Yalaz, Ceren. AU - Pan, Dipanjan. PY - 2012/8/8. Y1 - 2012/8/8. N2 - A synthetic methodology of preparing novel membrane stable, responsive dyes is revealed in this manuscript. 1,3-Bis(arylimino)isoindole dyes were synthesized and their properties to undergo intramolecular hydrogen bonding was studied with fluorescence spectroscopy in varying solvent polarities. Based on the functional moieties, compound that is capable of hydrogen donor and acceptor interactions produces predominant photoexcitation in comparison to the responsive dyes that lack these functionalities. These dyes, by the virtue of the presence of long chain acyl groups could be incorporated stably within the phospholipids membrane of core-shell nanoparticles. Nanoparticle was cracked to release the dye from a hydrophobic to a hydrophilic environment. A ...