357 results about "Förster resonance energy transfer" patented technology

The present invention relates to methods and apparatuses for analyzing molecules, particularly polymers, and molecular complexes with extended or rod-like conformations. In particular, the methods and apparatuses are used to identify repetitive information in molecules or molecular ensembles, which is interpreted using an autocorrelation function in order to determine structural information about the molecules. The methods and apparatuses of the invention are used for, inter alia, determining the sequence of a nucleic acid, determining the degree of identity of two polymers, determining the spatial separation of specific sites within a polymer, determining the length of a polymer, and determining the velocity with which a molecule penetrates a biological membrane.

This invention provides tandem fluorescent protein construct including a donor fluorescent protein moiety, an acceptor fluorescent protein moiety and a linker moiety that couples the donor and acceptor moieties. The donor and acceptor moieties exhibit fluorescence resonance energy transfer which is eliminated upon cleavage. The constructs are useful in enzymatic assays.

The invention discloses a method for detecting fluorescence resonance energy transfer by using a water-soluble upconversion fluorescence nanomaterial as a fluorescence donor and using a carbon nanomaterial as a fluorescence receptor. The method comprises the following specific steps: (1) preparing the water-soluble upconversion fluorescence nanomaterial and performing surface marker to obtain a fluorescence donor solution; (2) preparing the carbon nanomaterial to obtain a fluorescence receptor solution; (3) mixing the fluorescence donor solution and the fluorescence receptor solution for incubation and measuring the fluorescence intensity to obtain a fluorescence quenching curve; (4) mixing certain-concentration fluorescence donor solution and certain-concentration fluorescence receptor solution for incubation, adding a target object with different concentrations for continuous incubation, measuring the fluorescence intensity and drawing a standard curve; (5) calculating the concentration of the target object in an actual sample according to the standard curve. According to the method, interference of the background fluorescence of a biological sample can be avoided, detection to serum or the target object in a whole blood sample can be directly realized, the washing and separation processes are not needed, the detection speed is high, and the cost is low.

The present invention includes nuclear receptor heterodimer and nuclear receptor-coactivator peptide assays for identifying ligands for nuclear receptors, utilizing scintillation proximity and fluorescence resonance energy transfer (FRET), and methods of using identified ligands.

A probe comprises: (1) a target binding site moiety which is attached to a first fluorescent polypeptide; (ii) a mimic moiety which is capable of binding to the target binding site moiety and is attached to a second fluorescent polypeptide; and (iii) a linker which connects the two fluorescent polypeptides and which allows the distance between said fluorescent polypeptides to vary, said fluorescent polypeptides being so as to display fluorescence resonance energy transfer (FRET) between them, wherein the linker comprises one or more of: (1) a sequence capable of being recognised and bound by an immobilized component; (2) a protease cleavage site; (3) a non-analyte binding site; (4) two or more copies of the sequence (SerGly3); or (5) one or more copies of a rod domain from a structural protein. Probes of the invention are used, for example, in the detection of a wide range of substances or in the identification of inhibitors of the interaction between two substances which, in the absence of an inhibitor, interact with each other.

The invention discloses a nucleic acid analyzing method based on cascade HCR (hybridization chain reaction), and belongs to the field of molecule detection. The nucleic acid analyzing method is characterized in that on the basis of single HCR, two stages of HCR reaction are designed, and the signals can be further amplified on the basis of single HCR; the hairpin nucleic acid probes marked with multiple different fluorescent dyes can be alternatively hybridized by a final target product, so as to form a branched DNA (deoxyribonucleic acid) nanometer structure; the signal output is provided bythe fluorescent resonance energy transfer, and the concentration of the target nucleic acid can be judged according to the change value of the fluorescence intensity of fluorophore. The nucleic acid analyzing method has the advantages that the nucleic acid analyzing method can be used for in-vitro detection of DNA and miRNA (miniature ribonucleic acid), the specificity is good, and the sensitivityis high; the nucleic acid analyzing method can be used for the imaging analysis of miRNA in cells, and be favorable for the early diagnosis on cancers.

An instrument is disclosed for fluorescence assays which is capable of reading many independent samples at the same time. This instrument provides enhanced throughput relative to single-sample instruments, and is well-suited to use in general fluorescence, time-resolved fluorescence, multi-band fluorescence, fluorescence resonance energy transfer (FRET), and fluorescence polarization. This invention is beneficial in applications such as high-throughput drug screening, and automated clinical testing. Also disclosed are means and methods for a fluorescence polarization measurement which is highly sensitive, inherently self-calibrated, and unaffected by lamp flicker or photobleaching. This fluorescence polarization invention can be practiced on a variety of fluorescence instruments, including prior-art equipment such as microscopes and multi-well plate readers.

The invention discloses a fluorescent test strip based on resonance energy transfer, and a preparation method and application for the fluorescent test strip. The fluorescent test strip comprises a bottom liner, a sample absorption mat, a combining mat, a chromatography membrane and a water-absorbent mat, wherein the sample absorption mat, the combining mat, the chromatography membrane and the water-absorbent mat are sequentially connected with one another closely and are attached to the bottom liner; antibodies marked by fluorescent receptors are attached to the combining mat; a detection line and a calibration line are arranged on the chromatography membrane; the detection line is close to the combining mat; the calibration line is close to the water-absorbent mat; antigens marked by fluorescent substances are attached to the detection line; proteins marked by fluorescent substances are attached to the calibration line; the antigens marked by the fluorescent substances and the antibodies marked by the fluorescent receptors can be combined by specificity of antigen and antibody reaction; and the proteins marked by the fluorescent substances do not react with the antibodies marked by the fluorescent receptors. The fluorescent test strip has the advantages of safety in operation, simplicity, convenience, sensitivity, low cost, speediness and the like, is wide in application range, and can be used for single-item detection or quick detection items such as multiple-item detection.

System, including methods, apparatus, and kits, for fluorescence resonance transfer (FRET) binding assays that are surface-based.

The present invention provides organically modified silica (ORMOSIL) nanoparticles into which have been incorporated two-photon absorption dye molecules. The two photon absorption dye displays a unique aggregation induced fluorescence enhancement behavior. As a result ORMOSIL nanoparticles with high amounts of the dye can be prepared. These particles can be used for imaging. In one embodiment, the nanoparticles can additionally have incorporated therein a photosensitizer. The photosensitzer can be activated by intraparticle fluorescence resonance energy transfer (FRET) from the dye aggregates resulting in enhanced fluorescence and singlet oxygen generation from photosensitizer under two-photon excitation conditions. Such nanoparticles can be used for photodynamic therapy applications.

The invention discloses a method of detecting adenosine with a fluorescent sensor on the basis of an aptamer. In the method, gold nano particles modified with the aptamer are used as a recognition probe and an energy acceptor, and carbon dots modified with an aptamer complementary chain are used as a fluorescent probe and an energy donor; through a hybridization reaction, fluorescence resonance energy transfer is carried out between the gold nano particles and the carbon dots, and fluorescence of the detection system is quenched. After addition of adenosine, the adenosine and the aptamer complementary chain are competitively combined with the aptamer, so that energy transfer efficiency between the gold nano particles and the carbon dots is weakened; and the fluorescence of the detection system is recovered, so that based on the change of the fluorescence signal, the method achieves quantitative detection of the adenosine. The method has strong specificity and simple operation, is low in required quantity of a sample, is high in sensitivity, can be used for detecting the adenosine in a blood sample and supplies useful analysis data for clinical diagnosis on diseases.

The invention relates to a method for simultaneously detecting a divalent mercury ion and a silver ion in water solution based on fluorescence resonance energy transfer, belonging to the field of heavy metal ion detecting technology. The method comprises the following steps: firstly, preparing a detecting probe, comprising following steps: (1), preparing a cadmium telluride (CdTe) quantum dot which is encapsulated by mercaptopropionic acid (MPA); (2), designing and composing a nucleic acid probe for detection; (3), preparing a fluorescent probe CdTe-DNA of quantum dots and nucleic acid; and secondly, detecting heavy metal ion Ag+ and/or Hg2+. The method provided by the invention can detect two ions simultaneously, the workload is low, the cost is low and the process is not complex.

The invention discloses a method for detecting DNA (deoxyribonucleic acid) glycosylase activity on basis of single quantum dot level.In detection, DNA glycosylase hOGG1 specifically recognizes and excises damaged guanine to leave an abasic site, apurinic endonuclease-1 further excises the abasic site to leave a nucleotide gap, and DNA polymerase beta polymerizes Cy5-dGTP at the gap to generate a double-tagging double-strand nucleotide substrate; by specific reaction between biotin and streptavidin, the DNA substrate is combined to the surface, covered with the streptavidin, of quantum dots to form a QD-DNA-Cy5 compound; due to reduction of spatial distance, fluorescence resonance energy transfer occurs between the quantum dots and Cy5, and Cy5 fluorescence signals can be observed in the unimolecular level.The method has the advantages of simplicity, quickness and sensitivity, and the lower limit of detection can reach 1.8*10<-6>U/microliter.

The invention provides a quantum dot-cyanine dye-folic acid biological probe. The probe structure comprises a probe which is formed by the quantum dot is bonded with the cyanine dye, and the cyanine dye is bonded with the folic acid. The invention further provides a preparation method of the quantum dot-cyanine dye-folic acid biological probe. The invention has the advantages of convenient preparation method and easy inducing quantum dot of the dye. The biological probe has the characteristics of targeted identifying tumor tissue and transferring fluorescence resonance energy, thereby not being capable of targeted identifying cancer cell and being capable of identifying the space location and the space structure of the cancer cell by the characteristic of transferring fluorescence resonance energy. The biological probe has the dual advantages of the quantum dot and the cyanine dye probe, and has simple preparation method, thereby being high-stability and high-efficiency targeted fluorescence mark. The probe has high sensitivity and less usage amount.

Dual nucleic acid probes with resonance energy transfer moieties are provided. In particular, fluorescent or luminescent resonance energy transfer moieties are provided on hairpin stem-loop molecular beacon probes that hybridize sufficiently near each other on a subject nucleic acid, e.g. mRNA, to generate an observable interaction. The invention also provides lanthanide chelate luminescent resonance energy transfer moieties on linear and stem-loop probes that hybridize sufficiently near each other on a subject nucleic acid to generate an observable interaction. The invention thereby provides detectable signals for rapid, specific and sensitive hybridization determination in vivo. The probes are used in methods of detection of nucleic acid target hybridization for the identification and quantification of tissue and cell-specific gene expression levels, including response to external stimuli, such as drug candidates, and genetic variations associated with disease, such as cancer.

The invention discloses a multi-color optical encoding nano-rod with silica shell. The multi-color optical encoding nano-rod takes the shape of a core shell, the shell is made of silicon dioxide and the kernel is fluorescence-encoded polylysine which contains fluorescent dye A and fluorescent dye B; the fluorescent dye A and fluorescent dye B are a fluorescence resonance energy transfer supplier-receptor pair. The invention also discloses a method for preparing the multi-color optical encoding nano-rod with silica shell, which includes the steps of enabling the fluorescent dye A and fluorescent dye B to react with the polylysine to prepare fluorescence-encoded polylysine, and wrapping the fluorescence-encoded polylysine, used as kernel material, in a silicon dioxide substrate through reverse microemulsion method; in this way, the multi-color optical encoding nano-rod with silica shell can be prepared. The multi-color optical encoding nano-rod with silica shell has the advantages of strong fluorescence intensity, good biological compatibility, good hydrophilicity, little leakage of dye and stable property.

The present invention relates to nanocrystals and methods for making the same; in particular, the invention relates to ternary or higher alloyed nanocrystals and methods for making such structures in aqueous or water-soluble solvents. In certain embodiments of the invention, methods of preparing ternary or higher alloyed nanocrystals involve providing at least first, second, and third nanocrystal precursors (e.g., NaHSe, ZnCl₂, and CdCl₂) and forming nanocrystal structures in an aqueous or water-soluble solvent. In some cases, nanocrystal precursor solutions may also include a water-soluble ligand (e.g., glutathione, GSH). As such, ternary or higher alloyed nanocrystals (e.g., Zn_xCd)—_xSe) comprising the at least first, second, and third nanocrystal precursors may be formed, and the water-soluble ligand may coat at least a portion of the surface of the ternary or higher alloyed nanocrystal. Advantageously, methods for forming nanocrystals described herein can be performed at low temperatures (e.g., less than 100 degrees Celsius), and, in some embodiments, do not require the use of organic solvents. The present inventors have applied these methods to prepare blue-emitting nanocrystals with emissions that are tunable between 400-500 nm, and with quantum yields of greater than 25% in aqueous solution. These nanocrystals may be highly water soluble and can be used in a variety of applications, including those involving cell culture, sensing applications, fluorescence resonance energy transfer, and in light-emitting devices.

The invention discloses a super-resolution imaging method based on fluorescence resonance energy transfer (FRET). The super-resolution imaging method comprises the following steps: 1) marking a sample to be detected with a fluorescent probe having high FRET efficiency, wherein the fluorescent probe having high FRET efficiency has a marked FRET molecule pair, the FRET molecule pair includes a first fluorophore (a donor) and a second fluorophore (a receptor), and the first fluorophore can exert FRET on the second fluorophore; and 2) carrying out laser scanning confocal microscope imaging at an excitation light threshold with an excitation light intensity capable of allowing the FRET molecule pair in the step 1) to generate FRET. A super resolution technology based on saturated FRET in the invention can realize super resolution imaging of a biological sample on an ordinary laser confocal microscope, and the method provided by the invention has high resolution.