841 results about "Biotin-streptavidin complex" patented technology

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.

Methods of reversal of the binding between a biotin compound and a biotin-binding compound are disclosed. A method of reversibly releasing a biotinylated moiety from a streptavidin (or avidin) coated support is shown as an example. The strong interaction between streptavidin or avidin-biotin is made much weaker by using a combination of modified streptavidin or avidin and modified biotin like desthiobiotin or a derivative thereof like DSB-X Biotin. A protein, such as an antibody may be biotinylated with the modified biotin. When this protein is isolated by binding the modified biotin to the modified streptavidin or avidin bound to an solid surface, it may be released under very gently and very rapid conditions by addition of free biotin. In contrast to proteins obtained by the prior art release methods the protein obtained using the previously available release methods, the proteins obtained using the methods disclosed herein will maintain their native conformation. Uses of the methods in various procedures including cell detachment procedures and techniques of detection, identification, determination, purification, separation and / or isolation of target proteins or nucleic acid molecules are also described.

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 invention relates to the immune analysis field, in particular relating to a method for performing an immunological test on biomolecules by avidin / streptavidin magnetic composite particles, which takes avidin / streptavidin magnetic composite particles as carriers, and comprises the following steps:, coating biotinylated antibody or antigen, adding a specimen to be tested and enzyme labeled antibody / enzyme labeled antigen / enzyme labeled anti-antibody, adding chromogenic substrate and testing.Biotin and avidin / streptavidin has strong binding capacity, can fix the antigen / antibody labeled by the biotin through the avidin / streptavidin labeled on the surface of the magnetic composite particles so as to use the system to test specific antibody / antigen. The test system has the advantages of high sensitivity, high specificity, high stability, strong adaptability and the like.

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.

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.

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.

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 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.

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 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.

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.

The invention relates to a homogeneous immunoassay kit, detection method and application thereof in the technical field of biology. The kit comprises a reagent I, a reagent II, a reagent III and a reagent IV, wherein the reagent I contains a first counterpart, and the first counterpart is a known antigen or a known antibody specially combined with an antigen to be detected in a sample to be detected; the reagent II contains a receptor which can react with singlet oxygen to generate a detectable signal and a second counterpart combined with the receptor; the reagent III contains a third counterpart specially combined with the first counterpart; the reagent IV contains a donor which can generate the singlet oxygen in an excitation state; the surface of the third counterpart is coated with biotin, and the surface of the donor is coated with streptavidin. By utilizing combined detection of the kit and the homogeneous immunoassay method of the antigen and the antibody, the screening difficulty of raw materials is reduced, and the detection sensitivity is promoted at the same time.

The invention provides application of a nucleic acid construct containing streptavidin elements to protein expression and purification, and particularly provides the nucleic acid construct. The nucleic acid construct has a formula I structure from 5' to 3', and the formula I is as follows: Z1-Z2-Z3 (I); and in the formula I, Z1, Z2 and Z3 are the elements used for constituting the construct correspondingly, all '-' are bonds or nucleotide connection sequences independently, Z1 represents a coding sequence of a tag protein, Z2 represents a connection sequence, and Z3 represents a coding sequence of a passive protein or a foreign protein. By applying the nucleic acid construct to a protein synthesis system (especially an in-vitro protein synthesis system), expression and purification of theforeign protein can be completed, and an RFU value of the synthesized foreign protein is increased.

The invention relates to a quantitative detection kit for NSE and a preparation method and application of the quantitative detection kit. The kit comprises a calibrator, a magnetic separation reagent, an enzyme reactant, a stable reinforcing agent and a chemiluminiscent substrate, wherein the calibrator is obtained by treating NSE antigen through a reducing agent solution and diluting the NSE antigen to a buffer solution containing a nonionic surfactant; the magnetic separation reagent is obtained by immunofixation of a biotinylation antibody and streptavidin magnetic particles; the enzyme reactant comprises a NSE tracing antibody marked by alkaline phosphatase; and the stable reinforcing agent comprises a multicomponent immune compound interfered by an anti-heterophilic antibody. The invention further relates to a preparation method of the kit and a method of applying the kit to quantitatively detect a tumor marker NSE. The kit is reliable in performance, high in flexibility, and wide in linear range, and matched up with an automatic instrument for use. At present, the kit has already obtained a third registration certificate of a diagnostic reagent in SFDA (State Food and Drug Administration).

Disclosed is an electrochemiluminescence immunoassay method, using a full reaction of a Ru(bpy) marked protein-primary antibody, a biotinylated protein-secondary antibody to be tested, and a sample to be tested; addition of a Streptavidin-coated magnetic particle to form a complex comprising an antigen, an antibody, and a magnetic particle; adsorption to an electrode surface by the magnetic particle; addition of a dibutyl ethanolamine solution; testing by means of an electrochemical method. Also disclosed is a corresponding electrochemiluminescence immunoassay detection kit.

The invention discloses a construction method of an aptamer sensor for measuring ochratoxin A, belonging to the technical field of detection of a biosensor. The construction method comprises the following steps of coating a PCR (Polymerase Chain Reaction) tube by streptavidin, hybridizing an aptamer and partially complementary DNA (Deoxyribose Nucleic Acid) fragments and fixing on the surface of the PCR tube, and constructing the aptamer sensor. The invention provides a single stranded DNA aptamer combined with the ochratoxin A at high specificity and high affinity, and DNA fragments, which are partially complementary to the aptamer, through recognition combination of the aptamer and the ochratoxin A, aptamer conformation is induced to change so as to release the DNA fragments, which are partially complementary to the aptamer, the fragments, which are partially complementary to the aptamer, are taken as PCR amplification templates, and the ochratoxin A is detected through amplified fluorescence signals. According to the method provided by the invention, ultra-sensitivity detection of the ochratoxin A is realized at low detection limit, high detection sensitivity and good specificity, and an effective method is provided for detection of the trace ochratoxin A and the other harmful substances.

The invention relates to a nanotechnology-based trace protein detection method, which combines enzyme-linked immunosorbent assay technology, tyramine signal amplification technology and the aggregation phenomenon of gold nanoparticles modified by different biological molecules, so an experimental method used for detecting trace proteins such as prostate specific antigen (PSA) and the like is established. The method comprises the following steps of: fixing an antibody aiming at the protein to be detected (such as the PSA) on the surface of a substrate; incubating another antibody with horseradish peroxidase (HRP) activity of the protein to be detected (such as the PSA) after capturing the protein to be detected in a sample, wherein the HRP catalyzes biotin-tyramide to generate biotin deposition under certain conditions; further amplifying a signal by using the aggregation phenomenon of the gold nanoparticles modified by biotin-labeled DNA and the gold nanoparticles modified by streptavidin; performing silver staining; and performing data analysis on an experimental result by using software. The method has the advantages of extremely low detection limit, wider detection range, capacity of detecting the antigen in a rabbit serum with complex compositions, and important application prospect.

The invention discloses a method for detecting a target substance in a to-be-detected sample based on fluorescent sensing analysis of an aptamer probe. The method comprises the following steps: (1) jointly incubating functional magnetic beads and the to-be-detected sample together, wherein the functional magnetic beads are obtained by hybridizing magnetic beads (a) of which the surfaces are modified with specifically recognized target substance and a probe (b) linked with streptavidin and a marker; (2), after the step (1) is completed, carrying out magnetic separation and collecting a supernatant; and (3) under the excitation effect of an excitation wavelength corresponding to the marker, detecting the supernatant obtained in the step (2) by virtue of a solid-phase chip of which the surface is modified with a dethiobiotin or a biotin and determining whether the target substance is contained in the to-be-detected sample according to the values of signals. The method disclosed by the invention is low in cost and simple and rapid and has the advantages of wide aptamer target molecules, good specificity and high sensitivity and the method can be stably used over 300 times.

The invention relates to a chemical illumination immunity analysis method for checking human cTnT, which uses acridiniumester and / or alkaline phosphatase as label. The immunity reaction uses two-site immunoassay and / or competition law. The immunity reaction can use streptavidin-biotin two-site immunoassay to improve sensitivity. The invention uses NaOH and H2O2 as acridiniumester illumination initiating agent, uses 1, 2-dioxo cyclohexane derivative (adamantine derivative) as the illumination substrate of alkaline phosphatase, and uses fluorescein derivative and surface activator as illumination renforcing agent. The solid carrier is orifice plate, macromolecule polymer tube (ball) and ferriferrous oxide magnetic particles or the like.

A quantitative method for performing an automated diagnostic assay, comprising: incubating a capture reagent with a streptavidin-coated medium to form a solid phase complex; washing the solid phase complex to remove excess capture reagent; incubating the solid phase complex with a serum sample to form an immune complex; washing the immune complex to remove any unbound sample; incubating the immune complex with a conjugate to create an immune-conjugate complex; washing the immune-conjugate complex to remove any unbound conjugate; introducing a substrate capable of generating a quantifiable response; and calibrating the response generated from introducing the substrate.

The invention discloses a liquid-phase chip for the early diagnosis of myocardial infarction, which mainly comprises coated microspheres, wherein, the coated microspheres comprise the microspheres which are coated by CK-MB capture antibodies, the microspheres which are coated by Mb capture antibodies, the microspheres which are coated by cTnI capture antibodies, the microspheres which are coated by GPBB capture antibodies, the microspheres which are coated by H-FABP capture bodies, detection antibodies which are respectively labeled by biotin, and a streptavidin phycoerythrin. The liquid-phase chip for the early diagnosis of the myocardial infarction which is provided by the invention has the advantages of high detection efficiency, a small number of the needed samples, strong specificity, high sensitivity, etc. At the same time, all the myocardial damage markers can be freely combined, thus the usage is convenient. Moreover, all the reactions are in the liquid-phase environment, which is better for keeping the natural conformation of the protein, and leads the reaction of a probe and an object to be detected to be faster and more complete, thus greatly improving the detection sensitivity and the linear range.

The invention discloses a quantitative detection kit combining magnetic particles with chemiluminescence immunoassay for beta human chorionic gonadotropin (beta-hCG). The kit comprises beta-hCG calibrators, magnetic particle suspension coupled with streptavidin, a beta-hCG antibody labeled with biotin, a beta-hCG abzyme combination, a beta-hCG quality controller, chemiluminescence liquor A, chemiluminescence liquor B, 20 times concentrated washing liquor, and a reaction tube, wherein enzyme adopted by the beta-hCG abzyme combination is horse radish peroxidase with the purity RZ being more than or equal to 3.0 and the activity being more than or equal to 250U / ml. The invention also discloses a preparation method of the kit. Compared with the conventional kit, the quantitative detection kit is simple and convenient to operate, is safe, does not cause environment pollution, and also has the advantages of wide concentration range, low cost, good stability and the like of detection samples.

The invention discloses an immune-electrochemical sensor based on an AuNPs@AgNCs nano composite material, construction and applications thereof. Ab1 is fixed by graphene, PSA is taken as the target analyte, SA-AuNPs@AgNCs labeled by streptavidin is easily combined with monoclonal antibody Ab2(biotin-Ab2) which has been modified by biotin, and thus a PSA immunity sensor can be prepared by a sandwich interlaying method through the specific reactions between an antibody and an antigen. When the immune sensor is used, silver and H2O2 are precipitated on the sensor through electric catalytic reduction reactions, the detection is rapid and sensitive, has good specificity, and is capable of detecting the concentration of PSA with an ultralow content. The concentrations of f-PSA and t-PSA in serum of prostatic hyperplasia patients and prostatic cancer patients can also be detected by the sensor, so the sensor has an important meaning for diagnosis and identification on gray areas in prostatic cancer diagnosis.