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Enzyme-linked Immunosorbent Assay
The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence of a ligand (commonly a protein) in a liquid sample using antibodies directed against the protein to be measured. ELISA has been used as a diagnostic tool in medicine, plant pathology, and biotechnology, as well as a quality control check in various industries. In the most simple form of an ELISA, antigens from the sample to be tested are attached to a surface. Then, a matching antibody is applied over the surface so it can bind the antigen. This antibody is linked to an enzyme and then any unbound antibodies are removed. In the final step, a substance containing the enzyme's substrate is added. If there was binding, the subsequent reaction produces a detectable signal, most commonly a color change. Performing an ELISA involves at least ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3,3',5,5'-Tetramethylbenzidine
3,3′,5,5′-Tetramethylbenzidine or TMB is a chromogenic substrate used in staining procedures in immunohistochemistry as well as being a visualising reagent used in enzyme-linked immunosorbent assays (ELISA). TMB is a white solid that forms a pale blue-green liquid in solution with ethyl acetate. TMB is degraded by sunlight and by fluorescent lights. Enzymatic assay TMB can act as a hydrogen donor for the reduction of hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ... to water by peroxidase enzymes such as horseradish peroxidase. The resulting one-electron oxidation product is a diimine-diamine complex, which causes the solution to take on a blue colour, and this colour change can be read on a spectrophotometer at the wavelengths of 370 and 650 n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Antibody
Primary and secondary antibodies are two groups of antibodies that are classified based on whether they bind to ''antigens or proteins'' directly or target another (primary) antibody that, in turn, is bound to an ''antigen or protein''. Primary A primary antibody can be very useful for the detection of biomarkers for diseases such as cancer, diabetes, Parkinson’s and Alzheimer’s disease and they are used for the study of absorption, distribution, metabolism, and excretion (ADME) and multi-drug resistance (MDR) of therapeutic agents. Secondary Secondary antibodies provide signal detection and amplification along with extending the utility of an antibody through conjugation to proteins. Secondary antibodies are especially efficient in immunolabeling. Secondary antibodies bind to primary antibodies, which are directly bound to the target antigen(s). In immunolabeling, the primary antibody's Fab domain binds to an antigen and exposes its Fc domain to secondary antibody. Then ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radioimmunoassay
A radioimmunoassay (RIA) is an immunoassay that uses radiolabeled molecules in a stepwise formation of immune complexes. A RIA is a very sensitive in vitro assay technique used to measure concentrations of substances, usually measuring antigen concentrations (for example, hormone levels in blood) by use of antibodies. Although the RIA technique is extremely sensitive and extremely specific, requiring specialized equipment, it remains among the least expensive methods to perform such measurements. It requires special precautions and licensing, since radioactive substances are used. In contrast, an immunoradiometric assay (IRMA) is an immunoassay that uses radiolabeled molecules but in an immediate rather than stepwise way. A radioallergosorbent test (RAST) is an example of radioimmunoassay. It is used to detect the causative allergen for an allergy. Method Classically, to perform a radioimmunoassay, a known quantity of an antigen is made radioactive, frequently by labeling it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunoassay
An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoassay is often referred to as an " analyte" and is in many cases a protein, although it may be other kinds of molecules, of different sizes and types, as long as the proper antibodies that have the required properties for the assay are developed. Analytes in biological liquids such as serum or urine are frequently measured using immunoassays for medical and research purposes. Immunoassays come in many different formats and variations. Immunoassays may be run in multiple steps with reagents being added and washed away or separated at different points in the assay. Multi-step assays are often called separation immunoassays or heterogeneous immunoassays. Some immunoassays can be carried out simply by mixing the reagents and sample and making a p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand Binding Assays
A ligand binding assay (LBA) is an assay, or an analytic procedure, which relies on the binding of ligand molecules to receptors, antibodies or other macromolecules. A detection method is used to determine the presence and extent of the ligand-receptor complexes formed, and this is usually determined electrochemically or through a fluorescence detection method. This type of analytic test can be used to test for the presence of target molecules in a sample that are known to bind to the receptor. There are numerous types of ligand binding assays, both radioactive and non-radioactive.Joseph R. Lakowicz. (1991) Topics in Fluorescence Spectroscopy: Biochemical applications. As such, ligand binding assays are a superset of radiobinding assays, which are the conceptual inverse of radioimmunoassays (RIA). Some newer types are called "mix-and-measure" assays because they do not require separation of bound from unbound ligand. Ligand binding assays are used primarily in pharmacology to p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectrophotometry
Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. Spectrophotometry uses photometers, known as spectrophotometers, that can measure the intensity of a light beam at different wavelengths. Although spectrophotometry is most commonly applied to ultraviolet, visible, and infrared radiation, modern spectrophotometers can interrogate wide swaths of the electromagnetic spectrum, including x-ray, ultraviolet, visible, infrared, and/or microwave wavelengths. Overview Spectrophotometry is a tool that hinges on the quantitative analysis of molecules depending on how much light is absorbed by colored compounds. Important features of spectrophotometers are spectral bandwidth (the range of colors it can transmit through the test sample), the percentage of sample-transmission, the logarithmic range of sample-absorption, and sometimes a percenta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflectometry
Reflectometry uses the reflection of waves at surfaces and interfaces to detect or characterize objects. There are many different forms of reflectometry. They can be classified in several ways: by the used radiation (electromagnetic, ultrasound, particle beams), by the geometry of wave propagation (unguided versus wave guides or cables), by the involved length scales (wavelength and penetration depth versus size of the investigated object), by the method of measurement (continuous versus pulsed, polarization resolved, ...), and by the application domain. Used radiation Electromagnetic radiation of widely varying wavelength is used in many different forms of reflectometry: * Radar and Lidar: Reflections of electromagnetic pulses are used to detect the presence and to measure the location and speed of objects like aircraft, missiles, ships, cars. * Characterization of Semiconductor and Dielectric Thin Films: Analysis of reflectance data utilizing the Forouhi Bloomer dispersion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analysis
Analysis ( : analyses) is the process of breaking a complex topic or substance into smaller parts in order to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle (384–322 B.C.), though ''analysis'' as a formal concept is a relatively recent development. The word comes from the Ancient Greek ἀνάλυσις (''analysis'', "a breaking-up" or "an untying;" from ''ana-'' "up, throughout" and ''lysis'' "a loosening"). From it also comes the word's plural, ''analyses''. As a formal concept, the method has variously been ascribed to Alhazen, René Descartes ('' Discourse on the Method''), and Galileo Galilei. It has also been ascribed to Isaac Newton, in the form of a practical method of physical discovery (which he did not name). The converse of analysis is synthesis: putting the pieces back together again in new or different whole. Applications Science The field of chemistry uses analysis in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analyte
An analyte, component (in clinical chemistry), or chemical species is a substance or chemical constituent that is of interest in an analytical procedure. The purest substances are referred to as analytes, such as 24 karat gold, NaCl, water, etc. In reality, no substance has been found to be 100% pure in its quality, so a substance that is found to be most pure (for some metals, 99% after electrolysis) is called an analyte. See also *Analytical chemistry * Immunoassay *Magnetic immunoassay Magnetic immunoassay (MIA) is a type of diagnostic immunoassay using magnetic beads as labels in lieu of conventional enzymes (ELISA), radioisotopes ( RIA) or fluorescent moieties ( fluorescent immunoassays) to detect a specified analyte. MIA invo ... References Analytical chemistry {{Analytical-chemistry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antigen-antibody Interaction
Antigen-antibody interaction, or antigen-antibody reaction, is a specific chemical interaction between antibodies produced by B cells of the white blood cells and antigens during immune reaction. The antigens and antibodies combine by a process called agglutination. It is the fundamental reaction in the body by which the body is protected from complex foreign molecules, such as pathogens and their chemical toxins. In the blood, the antigens are specifically and with high affinity bound by antibodies to form an antigen-antibody complex. The immune complex is then transported to cellular systems where it can be destroyed or deactivated. The first correct description of the antigen-antibody reaction was given by Richard J. Goldberg at the University of Wisconsin in 1952. It came to be known as "Goldberg's theory" (of antigen-antibody reaction). There are several types of antibodies and antigens, and each antibody is capable of binding only to a specific antigen. The specificity of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand Binding Assay
A ligand binding assay (LBA) is an assay, or an analytic procedure, which relies on the binding of ligand molecules to receptors, antibodies or other macromolecules. A detection method is used to determine the presence and extent of the ligand-receptor complexes formed, and this is usually determined electrochemically or through a fluorescence detection method. This type of analytic test can be used to test for the presence of target molecules in a sample that are known to bind to the receptor. There are numerous types of ligand binding assays, both radioactive and non-radioactive.Joseph R. Lakowicz. (1991) Topics in Fluorescence Spectroscopy: Biochemical applications. As such, ligand binding assays are a superset of radiobinding assays, which are the conceptual inverse of radioimmunoassays (RIA). Some newer types are called "mix-and-measure" assays because they do not require separation of bound from unbound ligand. Ligand binding assays are used primarily in pharmacology to p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal (information Theory)
In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The '' IEEE Transactions on Signal Processing'' includes audio, video, speech, image, sonar, and radar as examples of signal. A signal may also be defined as observable change in a quantity over space or time (a time series), even if it does not carry information. In nature, signals can be actions done by an organism to alert other organisms, ranging from the release of plant chemicals to warn nearby plants of a predator, to sounds or motions made by animals to alert other animals of food. Signaling occurs in all organisms even at cellular levels, with cell signaling. Signaling theory, in evolutionary biology, proposes that a substantial driver for evolution is the ability of animals to communicate with each other by developing ways of signaling. In human engineering, signals are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
