48 results about "Fluorescence correlation spectroscopy" patented technology

The invention relates to a lasing fluorescence scanning imaging-fluorescence correlation spectrum unimolecule detecting instrument. Cover glass or a sample cell is arranged on an X-Y scanning platform; a microscope objective is installed on a Z-direction locator. Expended laser is filtered by an excitation filter, and then reflected into the objective by a dichroic mirror, and finally radiated in a sample above the cover glass after being focused by the objective; the sample generates fluorescence; and the generated fluorescence is collected by the same objective, passes through the dichroic mirror, and stray light is filtered off by an emission filter, and finally the filtered fluorescence is focused by a focusing lens on a small hole which is coupled with a single photon detector; and a signal generated by the single photon detector enters a computer through a data acquisition card. In the computer, three-dimension displacement and positioning system control software control the X-Y scanning platform to do X-Y two-dimension movement, and the Z-direction locator controls the focus of the objective to do Z-direction movement, thereby forming the three-dimension scanning to the sample; and three-dimension space position information and the signal generated by the single photon detector construct three-dimension scanning images and fluorescence correlation spectrum curves in the computer.

Techniques for inferring particle dynamics from certain data include determining multiple models for motion of particles in a biological sample. Each model includes a corresponding set of one or more parameters. Measured data is obtained based on measurements at one or more voxels of an imaging system sensitive to motion of particles in the biological sample; and, determining noise correlation of the measured data. Based at least in part on the noise correlation, a marginal likelihood is determined of the measured data given each model of the multiple models. A relative probability for each model is determined based on the marginal likelihood. Based at least in part on the relative probability for each model, a value is determined for at least one parameter of the set of one or more parameters corresponding to a selected model of the multiple models.

The present invention relates to novel fluorinated 3,6-diaminoxanthene compounds derived from the basic structural formula (I) and to their uses as photostable fluorescent dyes, e.g. for immunostainings and spectroscopic and microscopic applications, in particular in conventional microscopy, stimulated emission depletion (STED) reversible saturable optically linear fluorescent transitions (RESOLFT) microscopy, and fluorescence correlation spectroscopy. The claimed compounds are also useful as molecular probes in various spectroscopic applications.

A time-resolved spectroscopy system employing a time-division multiplexing optical device with no dispersive optical elements to perform lifetime and concentration measurements in multi-species samples, is disclosed. Some examples include fluorescence and cavity ring-down spectroscopy. The system is unique in its compactness and simplicity of operation. In one embodiment, the system makes use of only one photo-detector and an efficient linear regression algorithm. The system offers a measurement time for multiple species measurements of less than 1 s. The system can also be used to perform fluorescence correlation spectroscopy and fluorescence cross-correlation spectroscopy. Four methods to de-convolve a multi-component, exponentially decaying optical signal such as obtained with the system disclosed here, are presented. These methods may be applied to the measurement of fluorescence decay lifetimes and cavity ring-down times, the latter used extensively for the measurement of gas and trace-gas concentrations in complex mixtures, via absorption spectroscopy.

Techniques are provided for illuminating a sample by using total internal reflection (TIR) from a diffraction limited focused annular illumination beam. The illumination forms an affected region and an overlapping confocal region that may have dimensions the below 1 μm. An adjustable diffractive optical element, for example, may create a second order Bessel profile laser beam that is focused on a sample using a high-numerical aperture objective under TIR. An evanescent field excites fluorescent biological material in the confocal region, and fluorescence from the material is analyzed in fluorescence correlation spectroscopy system.

There are provided an apparatus, a method and a computer program for fluorescence correlation spectroscopy (FCS), which can reduce the number of times of fluorescence measurements of control samples as few as possible for a measurement by FCS in detecting existence ratios of the respective components contained in a sample. In the inventive apparatus, method and computer program for detecting an existence ratio of each of components with a fluorescent label contained in a solution sample by FCS, using a value of a ratio of a translational diffusion time of each of the components based upon the knowledge that a ratio of a translational diffusion time of each of the components is conservative under different measurement conditions etc.

A method is disclosed for analyzing particles or biomolecules in a liquid sample, including: detecting a signal and fluctuations in the signal from a detection volume in the sample; wherein the signal is generated from signal-generating molecules in the medium surrounding the particles or biomolecules and the fluctuations are transient reductions in the signal as the particles or biomolecules transit through the detection volume; and analyzing the detected fluctuations to obtain information about the particles or biomolecules in the liquid sample. At least one example embodiment of the present invention relates to a fluorescence correlation spectroscopy system including a laser, a zero-mode waveguide, guiding device for guiding the laser into the zero-mode waveguide, device for collecting fluorescence emission from excited molecules within the waveguide, a detector for detecting the fluorescence emission and means for autocorrelating the detected fluorescence signal, wherein the detector comprises a photomultiplier tube. Moreover, at least one embodiment relates to the use of a fluorescence correlation spectroscopy system for analyzing molecules of interest in a sample by detecting and analyzing fluctuations in a fluorescence signal that is generated from sample molecules surrounding the molecules of interest, wherein the fluctuations are transient reductions in the detected fluorescence signal.

The invention relates to novel and improved photostable rhodamine dyes of the general structural formulae I or II and their uses as fluorescent markers, e.g. for immunostainings and spectroscopic and microscopic applications, in particular in conventional and stimulated emission depletion (STED) microscopy and fluorescence correlation spectroscopy. The partially deuterated analogues are useful as molecular mass distribution tags in mass spectroscopic applications. wherein R¹=an unsubstituted or substituted alkyl group, including a cycloalkyl group, or heterocycloalkyl group; R²═H, an unsubstituted or substituted alkyl group, including a cycloalkyl group, or heterocycloalkyl group, or an unsubstituted or substituted aryl group or heteroaryl group, or any combination of such groups; X═CH₂, C═O, C═NOR^a, C═NNR^aNR^b, CH(OR^a), O, S, SO, SO₂, or any other derivatives of these groups, with Ra and Rb independently being H or an organic residue, in particular an unsubstituted or substituted (cyclo) alkyl group or heterocycloalkyl group, an unsubstituted or substituted aryl group or heteroaryl group; Z=a negatively charged group with 1, 2, 3, 4 or 5 charges per anion.

The invention discloses a donor-acceptor distance distribution measuring method based on fluorescence correlation spectroscopy. Fluorescent labeled living cells of donors and acceptors are subjected to a selective donor excitation operation through a fluorescence correlation spectroscopy module of a laser scanning confocal microscope in different laser power. A correlation card acquires photon number fluctuation signals of a donor channel and an acceptor channel to form a self-correlation curve. Energy transfer rate and energy transfer efficiency can be calculated through triplet state analysis of the self-correlation curve of the acceptors. In addition, triplet state distribution of the energy transfer rate and the energy transfer efficiency can be inverted from the self-correlation curve of the triplet state of the acceptors through a maximum entropy algorithm so that donor-to-acceptor distance distribution can be calculated. A fluorescence correlation spectrum analysis method itself is an excellent technology of measuring concentration of a dilute solution, so that the measuring method can be used for measuring donor-acceptor non-paired fluorescence resonance energy transfer efficiency and donor-acceptor non-paired distance distribution after integration items of overlap items of the spectrum being corrected with respect to the donor-acceptor concentration proportion. The measuring method is convenient to use and high in measuring precision.

The invention discloses an in-water polycyclic aromatic hydrocarbon detection method based on two-dimensional fluorescence correlation spectroscopy.The method includes: (1) preparing mixed experimental polycyclic aromatic hydrocarbon aqueous solutions of different concentrations; (2) scanning fluorescence spectrums of each mixed experimental polycyclic aromatic hydrocarbon aqueous solution under different excitation wavelengths to obtain one-dimensional dynamic fluorescence spectrums; (3) adopting data of the obtained one-dimensional dynamic fluorescence spectrums to form a spectrum matrix, and carrying out two-dimensional correlation calculation to obtain a synchronous two-dimensional fluorescence correlation spectrum matrix; (4) establishing a quantitative analysis model according to the synchronous two-dimensional fluorescence correlation spectrum matrix and a concentration variable matrix of anthracene, phenanthrene and pyrene in each mixed polycyclic aromatic hydrocarbon aqueous solution; (5) substituting a synchronous two-dimensional fluorescence correlation spectrum of an unknown sample aqueous solution into the quantitative analysis model established at the step (4) to obtain concentrations of anthracene, phenanthrene and pyrene in the unknown sample aqueous solution.The in-water polycyclic aromatic hydrocarbon detection method based on two-dimensional fluorescence correlation spectroscopy has the advantages that feature information of polycyclic aromatic hydrocarbon pollutants can be extracted more effectively, quantitative analysis of in-water polycyclic aromatic hydrocarbon is realized, and easiness in operation and high analysis efficiency and analysis precision are achieved.

The present invention relates to a fluorescence correlation spectroscopy system (1) for analyzing particles in a medium (2), including a means (3) for detecting the light (7) emitted by the particles in the medium (2), said means (3) being coupled to a waveguide (4), for which purpose the end piece of the guide (4) comprises a means (4b; 5) for confining the light (7) injected into the guide (4).

An apparatus for and method of detecting a binding event between biomolecules is disclosed and includes admixing a target molecule including a first fluorophore and membrane vesicles including a trifunctional linker molecule, said trifunctional linker molecule including a second fluorophore, to form a sample, introducing a library of elements into said sample, each of said library elements having a binding affinity for said trifunctional linker molecule, and, screening said sample for fluorescence from said first fluorophore and said second fluorophore, such fluorescence indicative of a binding event between an element from said library of elements and said target molecule.

With the different methods of fluorescence correlation spectroscopy, physical and biological transport processes in or between cells in the microscopic range, for example diffusion processes, can be analyzed. For this purpose, correlations of the fluorescence measurement data are determined for different sample regions and mathematical transport models are adapted thereto. Erroneous fluorescence correlation analyses were previously identified on the basis of the properties of the adapted model function parameters and were discarded. The a-priori knowledge necessary for the identification had to be obtained in time-consuming series of tests. With the invention, sample properties can be determined in a simpler, quicker and more exact way from fluorescence correlations. A suitability degree for one or more regions of the sample is determined for a correlation evaluation, describing quantitatively the information content of the respective region, or the error to be expected from a correlation evaluation, and can thus already be used before a correlation evaluation as a criterion for filtering/selecting the respective region. In this way, elaborate correlation calculations can be dispensed with in non-informative sample regions.

The invention discloses a method for detecting polyelectrolyte conformation transformation in a flow field. The method comprises the following steps of: marking a to-be-detected polyelectrolyte by adopting a fluorescent dye capable of reflecting local environmental change; constructing a micro-fluidic channel; measuring the sizes of excitation spaces of the fluorescent dye with the known diffusioncoefficient at different positions in the micro-fluidic channel in the longitudinal height direction by adopting a fluorescence correlation spectrum; determining flow field flow velocities at different positions of the micro-fluidic channel when an external injection pump provides different apparent flows by adopting fluorescence correlation spectroscopy; taking a dilute solution of polyelectrolyte as a flowing medium, and determining spectra of the dilute solution at different positions in the micro-fluidic channel by adopting a single-molecule fluorescence spectrum; obtaining the local environment change of the polyelectrolyte according to the fluorescence intensity of the fluorescent dye marked on the polyelectrolyte, reflecting the concentration change of the counter ions according tothe local environment change, and obtaining the polyelectrolyte conformation transformation information according to the concentration change of the counter ions. The method is suitable for researching the influence on the polyelectrolyte conformation when a flow field and other factors coexist.