1586 results about "Streptavidin" patented technology

The invention concerns a polypeptide selected from muteins of streptavidin which is characterized in that it (a) contains at least one mutation in the region of the amino acid positions 44 to 53 with reference to wild type-(wt)-streptavidin and (b) has a higher binding affinity than wt-streptavidin for peptide ligands comprising the amino acid sequence Trp-X-His-Pro-Gln-Phe-Y-Z in which X represents an arbitrary amino acid and Y and Z either both denote Gly or Y denotes Glu and Z denotes Arg or Lys. In addition nucleic acids coding for the polypeptide, a vector containing this nucleic acid, a cell transfected with the vector as well as the use of a polypeptide in a method for the isolation, purification or determination of proteins are disclosed. Yet a further subject matter is a reagent kit containing the polypeptide.

The invention relates to a liquid phase chip for joint detection of multiple tumor markers and a preparation method thereof. The liquid phase chip comprises micro-balloons of a coupled antibody (at least two of the followings: AFP, CEA, CA125, CA153, CA19-9, CA242, CA72-4, PSA, HGH, Beta-HCG), corresponding biotin-labeled detection antibodies, streptavidin phycoerythrin and vegetable hydrosol or polysaccharide hydrosol which has a solute content of 1-10 wt per thousand and does not contain protein. The preparation of the liquid phase chip comprises refining and purification of hydrosol, coupling between captured antibodies and micro-balloons, preparation of biotin-labeled antibodies, dispersing the coupled micro-balloons into the vegetable hydrosol or the polysaccharide hydrosol, and the like. The liquid phase chip has the advantages of stable performance, good micro-balloon dispersivity, long preservation time, fast and convenient use and operation, small amount of samples in use, high detection sensitivity, wide linear scope and low detection cost, can detect ten tumor markers at most at one time, and requires a cost which is a quarter of the total fee of conventional methods.

Engineered microparticles, libraries of microparticles, and methods relating thereto. The microparticles are distinguishable based on differences in dielectric response to an applied electric field. In different embodiments, the dielectric differences may be engineered through, but not limited to, dielectrically dispersive materials, surface charge, and / or fluorescence. Gangliosides may be incorporated with the microparticles to control aggregation. Vesicles including erythrocyte ghosts may be used as a basis for microparticles. The microparticles may utilize a biotin streptavidin system for surface functionalization.

Aggregation is a major cause of the misbehavior of proteins. A system for modifying a protein to create a more stable variant is provided. The method involves identifying non-conserved hydrophobic amino acid residues on the surface of a protein, suitable for mutating to more hydrophilic residues (e.g., charged amino acids). Any number of residues on the surface may be changed to create a variant that is more soluble, resistant to aggregation, has a greater ability to re-fold, and / or is more stable under a variety of conditions. The invention also provides GFP, streptavidin, and GST variants with an increased theoretical net charge created by the inventive technology. Kits are also provided for carrying out such modifications on any protein of interest.

The invention relates to the immunoassay medical field, particularly provides a magnetic particle separation chemiluminescence immunoassay assay kit and a preparation method thereof used for detecting disease related markers. The kit of the invention comprises: 1) a calibrator; 2) magnetic particles which are coated with streptavidin; 3) disease related marker antibodies of enzyme markers and biotin markers; and 4) a chemiluminescence substrate. Further, the method for preparing the kit according to the invention includes the following steps: 1) pure raw materials are used to prepare the calibrator; 2) the streptavidin is used to coat the magnetic particles; 3) the mixed liquid of the enzyme and the biotin markers are prepared; 4) the calibrator, the chemiluminescence substrate as well as the mixed liquid of the enzyme and the biotin markers are packaged in a separated way; and 5) a finished product is packaged. The kit has the advantages of convenience, rapidness, sensitivity, stability, and the like.

The present invention is directed to methodology that allows a variety of compounds to be attached to self-assembling peptides using biotin / streptavidin linkages. The peptides can be used to form a biologically compatible membrane that promotes the growth and differentiation of cells. The attached therapeutic agents can be used to promote this process and the gel along with the growing cells can be implanted at a site in vivo where tissue repair is needed. Alternatively, membranes can be used for culturing cells in vitro or can be used for delivering drugs in vivo in the absence of seeded cells.

In this invention, a biomarker discovery method has been developed using specific biotin-labeled oligonucleotide ligands and magnetic streptavidin beads. In one embodiment, the oligonucleotide ligands are firstly generated by whole-cell based SELEX technique. Such ligands can recognize target cells with high affinity and specificity and can distinguish cells that are closely related to target cells even in patient samples. The targets of these oligonucleotide ligands are significant biomarkers for certain cells. These important biomarkers can be captured by forming complexes with biotin-labeled oligonucleotide ligands and collecting the complexes using magnetic streptavidin beads, whereupon the captured biomarkers are analyzed to identify the biomarkers. Analysis of biomarkers include HPLC-Mass Spectroscopy analysis, polyacrylamide gel electrophoresis, flow cytometry, and the like. The identified biomarkers can be used for pathological diagnosis and therapeutic applications. Using the disclosed methods, highly specific biomarkers of any kinds of cells, in particular cancer cells, can easily be identified without prior knowledge of the existence of such biomarkers.

The use of a selective chemical and bioorthogonal reaction providing a covalent ligation such as the [3+2] cycloaddition, in targeted molecular imaging and therapy is presented, more specifically with interesting applications for pre-targeted imaging or therapy. Current pre-targeted imaging is hampered by the fact that it relies solely on natural / biological targeting constructs (biotin / streptavidin). Size considerations and limitations associated with their endogenous nature severely limit the number of applications. The present invention describes how the use of an abiotic, bio-orthogonal reaction which forms a stable adduct under physiological conditions, by way of a small or undetectable bond, can overcome these limitations.

The invention relates to a latex enhanced turbidimetric immunoassay kit of quantitatively detecting procalcitonin PCT. The kit comprises an R1 reagent, an R2 reagent and a calibrator, wherein the R1 reagent comprises a protecting agent, a reaction enhancing agent, a preservative and buffer solution; the R2 reagent comprises a protecting agent, a preservative, buffer solution and anti-human PCT antibody coated sensitization polystyrene latex particles; the calibrator comprises a protecting agent, a preservative, buffer solution and PCT recombinant protein; the human PCT antibody in the R2 reagent is linked with polystyrene latex particles through streptavidin-biotin; and the particle diameter of the latex particles in the R2 reagent is 40-500 nm. The kit can be used on a biochemical analyzer and a scatter turbidimetry analyzer for quantitatively detecting the PCT content in human blood. The invention provides the PCT detection kit which has the advantages of convenience, quickness, high sensitivity, strong specificity and accurate quantification; and the kit has high instrument compatibility, is low in detection cost and meets the requirements on PCT turbidimetric products in clinical use.

One-dimensional ring structures form M13 viruses were constructed by two genetic modifications encoding binding peptides and synthesis of a heterobifunctional linker molecule. The bifunctional viruses displayed an anti-streptavidin peptide and hexahistidine (SEO ID NO: 4) peptide at opposite ends of the virus as pIII and pIX fusions. Stoichiometic addition of the streptavidin-NiNTA linker molecule led to the reversible formation of virus-based nanorings with circumferences corresponding to lengths of the packagable DNAs. These virus-based ring structures can be further engineered to nucleate inorganic materials and form metallic, magnetic, or semiconductor nanorings using trifunctionalized viruses.

A homogeneous immunoassay method and system for quantitative determination of total immunoglobulin E and specific antibody levels to a plurality of allergens, in which a relatively small sampling of blood is required. The method utilizes relatively small microparticles in aqueous suspension. The immunoassay procedure is an immunometric sandwich procedure preferably utilizing biotin-streptavidin signal amplification techniques and R-phycoerytherin fluorescent labels.

The invention discloses a chromatographic detection kit based on an aptamer, as well as a preparation method and detection method of the kit. The test paper of the kit includes a bottom board, and a sample pad, a bonding pad, a cellulose nitrate film and a water absorption pad, which are adhered on the bottom board and overlap one another; a detection line is arranged on the side of the cellulose nitrate film close to the bonding pad, and a quality control line is arranged on the side of the cellulose nitrate film close to the water absorption pad; an A aptamer labeled by colloidal gold is applied on the bonding pad; a composite containing a B aptamer and streptavidin is applied on the detection line; streptavidin is applied on the quality control line; and both of the A aptamer and the B aptamer are aptamers labeled by biotin and capable of specifically identifying a same test object. The chromatographic detection kit can display the result in five minutes only by directly dropping a diluted sample to be tested into a sample hole, is simple, quick, sensitive, easy to read result, and convenient and simple to prepare, and so on, and has the advantages of simplicity in operation and high specificity without using antibodies and instruments.

The invention relates to an antibody chip kit for diagnosis of various tumors. The kit includes an antibody chip, a tumor marker standard substance mixture, a biotin-labeled tumor marker detection antibody mixture, and a fluorescein Cy3-labeled streptavidin, wherein the antibody chip includes a substrate, 16 kinds of tumor marker specific antibodies fixed on the surface of the substrate, and two kinds of positive controls, and the tumor marker standard substance mixture is a freeze-dried mixture obtained by mixing 16 kinds of standard tumor marker standard substances together according to a certain amount. The kit can detect 16 clinical commonly used tumor markers, overcomes the defects of complicated operation, single detection index, low sensitivity and the like in the prior art, has the advantages of being cheap, convenient, sensitive, accurate, high in throughput, and less in amount of samples, and can be popularized and large-scaled in common laboratories.

An apheresis column loaded with a solid support comprises one or more chemokines, in particular biotinylated chemokines, immobilized directly or indirectly on the support, in particular on a support carrying streptavidin. Also disclosed are uses of the column and the support and a method of depleting cells, in particular leukocytes, from the peripheral blood of a person suffering from an inflammatory condition such as Inflammatory Bowel Disease (IBD).

The invention relates to a chemiluminescence quantitative detection kit for procalcitonin, and a preparation method and detection method thereof. The kit comprises a procalcitonin series standard substance, a magnetic separation reagent (magnetic particle suspension coupled with streptavidin), a first reagent (anti-procalcitonin monoclonal antibody solution containing biotin N-hydroxysuccinimide ester label) and a second reagent (anti-procalcitonin monoclonal antibody solution containing alkaline phosphatase label). The sensitivity of the kit prepared from the magnetic particle suspension coupled with streptavidin, anti-procalcitonin monoclonal antibody solution containing biotin N-hydroxysuccinimide ester label and anti-procalcitonin monoclonal antibody solution containing alkaline phosphatase label is up to 0.008ng / ml; and the kit has the advantages of high accuracy, high precision, no need of prediluting the sample, and wide detection range, and is simple and time-saving to operate.

Networks of single-walled carbon nanotubes (SWCNTs) decorated with Au-coated Pd (Au / Pd) nanocubes are employed as electrochemical biosensors that exhibit excellent sensitivity (2.6 mA mM−1 cm−2) and a low estimated detection limit (2.3 nM) at a signal-to-noise ratio of 3 (S / N=3) in the amperometric sensing of hydrogen peroxide. Biofunctionalization of the Au / Pd nanocube-SWCNT biosensor is demonstrated with the selective immobilization of fluorescently labeled streptavidin on the nanocube surfaces via thiol linking. Similarly, glucose oxidase (GOx) is linked to the surface of the nanocubes for amperometric glucose sensing. The exhibited glucose detection limit of 1.3_M (S / N=3) and linear range spanning from 10 μM to 50 mM substantially surpass other CNT-based biosensors. These results, combined with the structure's compatibility with a wide range of biofunctionalization procedures, would make the nanocube-SWCNT biosensor exceptionally useful for glucose detection in diabetic patients and well suited for a wide range of amperometric detection schemes for biomarkers.

The invention relates to the immunoassay medical field, particularly provides a magnetic particle competition method chemiluminescence immunoassay assay kit and a preparation method thereof used for detecting hormones. The kit according to the invention comprises: 1) a calibrator; 2) magnetic particles which are coated with streptavidin; 3) hormone antigens of enzyme markers; and 4) a chemiluminescence substrate. Further, the method for preparing the kit according to the invention has the following steps: 1) pure raw materials are used to prepare the calibrator; 2) the antigens are used to coat the magnetic particles; 3) the antigens of the enzyme markers are prepared; 4) the calibrator, the chemiluminescence substrate and the antigens of the enzyme markers are packaged in a separated way; and 5) a finished product is packaged. The kit has the advantages of convenience, rapidness, sensitivity, stability, and the like.

The invention relates to a high-sensitivity trace of protein measuring method based on bead and nm metal probe, comprising: labelling the bead using monoclonal antibody of protein to measure; labelling the polyclonal antibody of protein to measure on nm metal probe and at the same time labelling a DNA probe with biotin label on the nm metal probe; labelling horseradish peroxidase on the DNA probe of nm metal probe by biotin-streptavidin reaction to form nm metal probe; mixing the labelled bead and nm metal probe and protein sample and incubating for a period of time at 37 degree; and then washing the nm metal probes which do not react; developing using TMB development system, therefore the protein can be quantificationally detected. The detection time can be reduced to 1-1.5 hours and the sensitivity can be pg / ml.

The invention discloses a multi-fluorescence immunity analysis method for quickly distinguishing PEDV, TGEV and PoRV. The method is easy to operate, a target amplified fragment is obtained through PCR, then hybridization is conducted on an amplified product, fluorescence coded microspheres and streptavidin-phycoerythrin, the MFi value is read through a detection instrument, and different types of viruses are distinguished. By means of the method, porcine epizootic diarrhea, swine transmissible gastroenteritis and pig group A rotavirus can be accurately detected at the same time, the specificity is high, the sensitivity is high, and the repeatability is good. Compared with a traditional detection method, various molecules of different purposes in the same sample are detected at the same time, the sample consumption is little, operation is simple and fast, and the detection cost can be greatly lowered.

A fusion protein for delivery of a wide variety of agents to a cell via antibody-receptor-mediated endocytosis comprises a first segment and a second segment: the first segment comprising a variable region of an antibody that recognizes an antigen on the surface of a cell that after binding to the variable region of the antibody undergoes antibody-receptor-mediated endocytosis, and, optionally, further comprises at least one domain of a constant region of an antibody; and the second segment comprising a protein domain selected from the group consisting of avidin, an avidin mutein, a chemically modified avidin derivative, streptavidin, a streptavidin mutein, and a chemically modified streptavidin derivative. Typically, the antigen is a protein. Typically, the protein antigen on the surface of the cell is a receptor such as a transferrin receptor-or an insulin receptor. The invention also includes an antibody construct incorporating the fusion protein that is either a heavy chain or a light chain together with a complementary light chain or heavy chain to form an intact antibody molecule. The invention further includes targeting methods and screening methods.

The invention provides a homogeneous luminescence immunoassay method for quantitatively analyzing multiple components simultaneously and a kit used for the method. Receptor microspheres containing various different fluoresceins are adopted, and antibody molecules for capturing different biological markers to be measured are enveloped in the method; in a measuring process, the multiple biological markers in a sample to be measured are combined with the corresponding antibody molecules on the surfaces of the receptor microspheres and biotinylated antibodies in a detection system respectively to form double-antibody sandwich compositions which are respectively connected with donor microspheres labeled with streptavidin; when the donor microspheres are irradiated by exciting light, all types of the receptor microspheres send out optical signals with different wavelengths; the intensities of the light with different wavelengths are respectively detected, so that the biological markers to be measured can be accurately quantified. The kit comprises the receptor microspheres containing chemiluminescence reagents and the fluoresceins, the biotinylated antibodies and the donor microspheres containing photosensitive substances. The homogeneous luminescence immunoassay method and the kit have the beneficial effects that simultaneous and quantitative measurement on multiple components is realized, and the detection cost is reduced.

The invention provides a diagnostic kit for determination of serum total IgE, a preparation method and an application method. The kit comprises an IgE standard substance, a biotin labeled rate anti-human IgE monoclonal antibody solution, a rabbit anti-human IgE polyclonal antibody coated acceptor microspheres solution and a streptavidin donor microspheres solution. The kit provided by the present invention solves a tedious washing step of current heterogeneous immunoassay kits, overcomes the defects of environmental pollution caused by radioimmunoassay and short shelf life, and overcomes the defects of poor repeatability of enzyme immunoassay analysis and easy hook effect generation, and the detection precision is higher than that of immuno-turbidimetric analysis.

The invention provides methods and compositions for azide tagging of biomolecules. In one embodiment of the invention, proteins are tagged by metabolic incorporation of prenylated azido-analog substrates. Examples of such analogs are azido farnesyl diphosphate and azido farnesyl alcohol. The azido moiety in the resulting modified proteins provides an affinity tag, which can be chemoselectively captured by an azide-specific conjugation reaction, such as the Staudinger reaction, using a phosphine capture reagent. When the capture agent is biotinylated, the resulting conjugates can be detected and affinity-purified by streptavidin-linked- HRP and streptavidin-conjugated agarose beads, respectively. The invention allows detection and isolation of proteins with high yield, high specificity, and low contamination without harsh treatment of proteins.

The invention relates to a nano gold biological composite probe, a detection method and application thereof. The detection method is characterized in that: the method comprises the following steps: firstly marking a bead through a monoclonal antibody of a protein to be tested; marking the polyclonal antibody of the protein to be tested on nano gold while and simultaneously marking a DNA probe with a biotin label; carrying out a biotin-streptavidin reaction on the DNA probe on the nano gold to make a lanthanide bonded with colloidal gold to construct the nano gold biological composite probe; mixing the bead of marked monoclonal antibody of the protein to be tested, the nano gold biological composite probe and a protein sample to be tested, carrying out the incubation on the mixture for a certain time at 37 DEG C; cleaning away the nano gold probe which does not react; adding a reinforcing liquid; and determining the fluorescence intensity so as to realize the aim of carrying out the quantitative determination on the protein to be tested. The method obviously improves the detection sensitivity of biomolecules, and is used for detecting a plurality of kinds of biomolecules synchronously. The method is widely applied in the fields of clinical diagnosis, antigen, antibody and nucleic acid detection, health quarantine, environmental tests, and the like.

Compositions and methods are disclosed which facilitate purification of oligomers and other compounds. The disclosed compositions are silyl compositions that can be directly coupled, or coupled through a linking group, to a compound of interest, preferably to an oligomer at the end of oligomer synthesis. The silicon atom includes between one and three sidechains that function as capture tags. In one embodiment, the capture tags are lipophilic, which allows a derivatized oligomer to be separated from failure sequences by reverse phase chromatography. In another embodiment, the capture tags are compounds with a known affinity for other compounds, which other compounds are preferably associated with a solid support to allow chromatographic separation. Examples include haptens, antibodies, and ligands. Biotin, which can bind to or interact with a streptavidin-bound solid support, is a preferred capture tag of this type.

The present invention provides vectors for expressing genomic streptavidin fusion cassettes. In the various embodiments, fusion proteins produced from these vectors are provided. In particular embodiments, fusion proteins comprising a single chain antibody and genomic streptavidin are provided as are vectors encoding the same. Also provided, are methods of using the fusion proteins of the present invention, and in particular, the use of scFvSA fusion proteins as diagnostic markers or as a cell specific targeting agents.

The invention provides a chemoluminescence immunoassay measuring kit and a preparation method thereof for quantificationally detect triiodothyronine (T3) magnetic particles. The kit mainly comprises a triiodothyronine serial calibration sample, magnetic particle solution coated by an anti-fluorescein isothiocyanate (FITC) monoclonal antibody, a T3 antigen marked by biotin, T3 monoclonal antibody marked by FITC, streptavidin marked by alkaline phosphatase, chemoluminescence substrate solution and 20-time concentrated washing solution. The invention adopts a competitive-method reaction mode, effectively utilizes the chemoluminescence technology combined with magnetic particles and biotin-avidin immunity magnifying technology principle to quantificationally detect the content of T3 in blood serum and blood plasma samples of human bodies and ensure the sensitivity of the detection. The kit is simple, convenient, fast, sensitive and stable to use, and provides a very valuable detection method for clinic diagnosis and scientific research works.

New protein coated surfaces, which have a high capacity for capturing target molecules, thus yielding assays with enhanced sensitivity, are disclosed. Surfaces prepared according to the present invention contain a coating consisting essentially of streptavidin, avidin or "NeutrAvidin" in polymeric form, wherein polymerization has been controlled to an extent such that the polymer is predominantly dimers, trimers and tetramers of the native molecule.

A method of preparing an antigen-immobilized immuno-fluorescence slide, the method comprising: immobilizing a C-reactive protein on a slide to prepare a protein chip; mixing an antibody that specifically binds to a target protein, with streptavidin to label the antibody with a fluorescent nanoparticle; immuno-reacting the antibody by competitive mixing, assaying with a fluorescence camera, wherein the immobilizing of the C-reactive protein on the slide comprises: modifying the slide with 3-aminopropyltrimethoxysilane to prepare a modified slide; hydrating the slide modified with 3-aminopropyltrimethoxysilane; activating the modified slide by using a glutaraldehyde solution; dissolving a C-reactive protein at a concentration of 0.01-0.5 mg / ml in a 30-70 mM phosphate buffer solution (pH 6.5-7.8) to prepare an antigen solution for immobilization; placing a petri dish comprising the slide on a spotting guide and spotting 1-100 μl of the antigen solution on spotting points; and performing a reaction on the slide prepared as described above for 1-6 hours to immobilize the antigen, and an immune-fluorescence slide prepared by using the method.

The invention discloses an ochratoxin A fluorescence detection test strip and application thereof, relates to a method for detecting ochratoxin A by using a fluorescence test strip of a quantum dot-labeled aptamer, and belongs to the technical field of fluorescence detection. The test strip comprises a lower water-absorbent pad (1), a quantum dot-coupled Aptamer 1 (2), a streptavidin-biotin-Aptamer 2 (3), a streptavidin-biotin-Aptamer 3 (4), an upper water-absorbent pad (5), a nitrocellulose membrane (6) and a bottom plate (7). By using a chromatography one-step competition principle, the test strip semiquantitatively detects ochratoxin A residue quantity in a semiquantitative detection sample through upper and lower colorimetric belts thereof, rapidly and accurately detects whether the sample contains the ochratoxin A within 15 min to determine whether the ochratoxin A is overproof, can meet the requirement of food safety on the detection of the ochratoxin A residue quantity, and is suitable for feeds, meat producing plants and government detection mechanisms; and compared with the prior art, the test strip has the characteristics of convenient use, economy, rapidness, simple manufacturing and low cost.