Abstract: Compounds and methods are disclosed for reversibly aggregating particles suspended in a liquid medium. The method comprises combining the liquid medium containing the particles with a polyionic polymer capable of aggregating the particles under conditions suitable for such aggregation. Thereafter, the particles are contacted with a chemical reagent capable of cleaving the polyionic polymer under conditions sufficient to reverse the aggregation. Optionally, magnetic particles are added to the liquid medium in the present method under conditions for non-specific binding and the medium including the aggregates is subjected to a magnetic field gradient to separate the aggregates from the medium. The compounds of the present invention are polyions. The aggregation of the particles is reversible upon contact with chemical agents which cleave at least some of the bonds within the polyionic polymer.

Abstract: A microassay card includes an upper layer containing wells for receiving a liquid sample. A second layer of the card, beneath the first layer, includes a supporting surface bound to a reactive species. A third layer includes a superabsorbent support impregnated with an indicator. Typically, the indicator is a substrate for an enzyme, such as a reduced dye precursor and a source of hydrogen peroxide necessary for the action of the enzyme upon the substrate to cause a spectral change in the absorbent layer. By selecting the structure of the first and second layers, the card can be formatted for a displacement assay or a competitive assay. The microassay card of the present invention is particularly useful for drug testing.

Abstract: A process for assaying at least one analyte uses a tracer which includes multiple detectable substances. A tracer composition includes at least one ligand labeled with a particulate label, the particulate label containing at least one detectable substance. Two or more detectable substances in the assay may be in the same particulate label or in different particulate labels conjugated to different ligands.

Abstract: A portion of an organic polymer article such as a membrane is made hydrophilic by exposing a hydrophobic surface of the article to a depth of about 50 to about 5000 angstroms to atomic oxygen or hydroxyl radicals at a temperature below 100.degree. C., preferably below 40.degree. C., to form a hydrophilic uniform surface layer of hydrophilic hydroxyl groups. The atomic oxygen and hydroxyl radicals are generated by a flowing afterglow microwave discharge, and the surface is outside of a plasma produced by the discharge. A membrane having both hydrophilic and hydrophobic surfaces can be used in an immunoassay by adhering antibodies to the hydrophobic surface. In another embodiment, the membrane is used in cell culturing where cells adhere to the hydrophilic surface. Prior to adhering cells, the hydrophilic surface may be grafted with a compatibilizing compound.

Abstract: There are described a device and method for doing confined reactions such as PCR amplification and detection, wherein solids (e.g., beads) used to obtain separation between bound and "free" label reagents, are transferred from region to region, specifically through a wash liquid so as to wash off the "free" label reagent from the solids. Separate chambers have dividers that are overcome by piercing or by liquification, to create passageways for the transfer of the solids. The passageways remain contained within the device.

Abstract: Methods and device are provided where a device comprising an absorbing nib, an external deformable container and an internal container having a frangible barrier are provided, where the nib and internal container comprise reagents which are interactive with a sample for measuring an analyte.

Abstract: An immunochromatographic assay device for the detection of an analyte in a liquid sample, the device including a housing that contains an opening for the application of the liquid sample and multiple liquid permeable materials located in the housing that are adapted to receive, treat and facilitate the movement of the sample through the housing; preferably, a first liquid permeable material is adapted to receive the liquid sample; a second liquid permeable material is positioned under the first liquid permeable material; a third liquid permeable material is positioned above the second liquid material; means are provided to prevent liquid communication between the first and third liquid permeable materials; a wicking material, in fluid contact with the third liquid permeable material receives the sample; and reagents are positioned in the housing that display the results of the immunoassay.

Abstract: A kit for the immunological assay of the human tissue plasminogen activator-human plasminogen activator inhibitor complex in a human specimen, which kit comprises(i) a monoclonal antibody (first antibody) against a human plasminogen activator inhibitor linked onto an insoluble solid carrier having a specular surface,(ii) a polyclonal antibody (second antibody) against a human tissue plasminogen activator labelled by an enzyme,(iii) a substrate and a reaction-discontinuing agent for the assay of the enzyme activity,(iv) a diluent, and(v) a detergent containing a nonionic surfactant having an HLB (Hydrophile Lipophile Balance) value of at least 16,and a method for the immunological assay of the above complex and a method for the immunological assay of the active human plasminogen activator inhibitor, respectively in a human specimen using this kit.

Abstract: New variants of electroactive and optoactive polymers are formed from the surface chemical modification and derivization of free-standing and substrate-supported polymer films. The free-standing or substrate-supported films are chemically modified at or near their surfaces to introduce hydrophilic and/or reactive functional groups, such as carboxylic acids, hydroxyls, and amines. Surface derivatization of the modified polymer film is achieved through the specific attachment of bioactive, immunoactive, electroactive, and catalytic agents to the surface of the electroactive or optoactive polymer film. In one embodiment, a polymer selected from polyacetylene, polypyrrole, polyanilane and polythiophene is modified to contain functional groups and an indicator reagent is covalently coupled to the functional groups. When an analyte in a sample reacts with the indicator reagent, electrical conductivity of the polymer is changed and presence of the analyte is indicated by the change in electrical conductivity.

Abstract: A patient's health is diagnosed by centrifuging blood samples in a transparent tube, which tube contains one or more groups of particles such as lyposomes or plastic beads of different densities for each group. Each group of density-defined particles carries antigens or antibodies which are specific to a complement antigen or antibody which may be in the blood sample being tested, and which are indicative of the patient's health. A label-tagged antibody which is specific to all bound antibody/antigen couples is added to the blood sample so as to form labeled antibody+antigen-antibody complexes (AAAC) in the blood sample. Upon centrifugation, the complexed particles will settle out in different areas in the tube according to the respective density of the particles, and the degree of label emission of the particle layers can enable qualitative or quantitative analyses of the blood sample to be made.

Abstract: A new and improved polymeric membrane for use in biological assays is provided. A blotting assay employing 1,2-dioxetanes as a source of chemiluminescence employs, as an improved membrane, a polymer comprised of at least one monomer of the formula: ##STR1## The membranes reduce background signal, improve sensitivity and reliability.

Abstract: Biologically active reagents are prepared from particles of copolymers having polyoxyalkylene side chains, each of which side chains has a molecular weight of at least about 88. The reagents are prepared by covalently attaching biologically active substances, for example antibodies, to the particles, directly or indirectly through reactive groups on the particle surface. These reagents are used to advantage in analytical elements and methods for the detection of specific binding ligands (such as immunological species) and immunoassays, and in purification methods as affinity chromatography reagents. Adsorption of undesirable proteins on the particles of the reagents was considerably reduced because of the specific composition of the particles.

Abstract: The invention relates to microparticles incorporating a series of two or more fluorescent dyes having overlapping excitation and emission spectra allowing efficient energy transfer from the excitation wavelength of the first dye in the series, transfer through the dyes in the series and re-emitted as an optical signal at the emission wavelength of last dye in the series, resulting in a desired effective Stokes shift which is controlled through selection of appropriate dyes.

Abstract: A method and device for measuring the binding affinity of a receptor to a ligand. According to one aspect of the invention, arrays of polymers are synthesized or immobilized on a substrate (212). The array of polymers is exposed to a fluorescently-labelled receptor in solutions of varying concentration. The fluorescence intensity of the labelled receptor is measured by way of, e.g., a photon counter using a confocal microscope (316). Binding affinity is determined through analysis of the relationship between fluorescence intensity and the solution concentration of the receptor. On-rates are measured as a kinetic increase in surface fluorescence intensity, and the on-rate constant rate extracted from fits to the data.

Abstract: An amperometric biosensor and method for the detection of hydrogen peroxide, NADH, or NADPH with high sensitivity includes an electrode having on its testing surface a three-dimensional redox polymer network in which peroxidase is immobilized.

Abstract: The present invention relates to a process for determining or detecting by immuno adherence a biological substance present in a sample, which consists in introducing the sample into a receptacle on whose walls there is a component which has a specific immunological affinity for the substance to be tested for, in adding magnetic particles on which there is a substance which has a specific immunological affinity for the substance to be tested for, in subjecting them to several successive magnetic actions in order to accelerate the deposition of the said particles onto the walls and to displace those which have not formed specific bonds with the substance to be tested for which adheres to the walls via the component with affinity which is fixed thereto, and in observing the particles deposited.

Abstract: The invention relates to a method based on fluorescence, especially time-resolved fluorescence for quantitative assay of a bioaffinity reaction involving bioaffinity components. The method comprises the labelling of one or several of the bioaffinity components participating in the reaction with a lanthanide chelate, forming of a lanthanide chelate for a fluorescence measurement after the reaction, and measuring the fluorescence of the chelate. The lanthanide (Eu, Tb, Sm or Dy) is brought to a strongly fluorescent form before the fluorescence measurement by incorporating the lanthanide in an aggregated particle that comprises the lanthanide chelate and a chelate of a fluorescence-increasing ion (Y, Gd, Tb, Lu or La) to bring about a cofluorescence effect. An aliphatic or aromatic beta-diketone is used as the chelating compound in the aggregate.

Abstract: A method is provided for immobilizing and preserving an immunologically reactive antigen substance such as antigenic cells or non-cell bound antigens for use in solid-phase immunoassay. The antigen substance is adsorbed and crosslinked on a support and contacted with a protecting solution and containing sugar and an antiseptic substance such as NaN.sub.3. The antigen substance is preferably centrifugally contacted with the support to shorten the time for adsorption. Crosslinking is with a solution of 1.0 to 5.0% formaldehyde or 0.003 to 0.06% glutaraldehyde. The antigenic cells can be a blood component such as platelets.

Abstract: A method is disclosed for coating the surface of an optical structure, such as a diffraction grating, useful for the detection of a ligand, which method comprises forming on the surface of the optical structure a thin, uniform layer of a polymerizable material, particularly one which polymerizes on exposure to light or heat, and subsequently exposing said material to polymerizing conditions. A specific binding partner is subsequently absorbed on or bound to the cured polymer layer, either directly or indirectly. Complex formation between the specific binding partner and ligand present in the sample to be analyzed alters the optical properties of the device and the change forms the basis of an assay.

Abstract: This invention relates to methods and apparatus for carrying out affinity separations of proteins under conditions optimized for recovering biologically active protein. The method utilizes a membrane-bound ligand first to capture and separate a ligate from a fluid mixture and subsequently to release said ligate in purified form. The present methods enhance the yield of active ligate recovered in the process. The invention has particular relevance to the recovery and purification of proteins from mixtures.

Abstract: Biologically active reagents are prepared from particles of copolymers having highly active succinimid groups. The reagents are prepared by covalently attaching biologically active substances, for example antibodies, to the particles, directly or indirectly through amide groups by displacement of highly active succinimid groups on the particle surface. These reagents are used to advantage in analytical elements, methods for the detection of specific binding ligands (such as immunological species) and immunoassays, and in purification methods such as affinity chromatography.

Abstract: Disclosed is a primary chromatographic support containing an immobilized flocculating agent for use as a separation media for a secondary support consisting of microparticles used in affinity separation and heterogeneous immunoassays. In a specific embodiment, a flocculating agent such as polyethyleneimine is immobilized on a chromatographic resin packed in a column. The column so formed is then used to trap microparticles having an affinity ligand or binder for the ligand affixed thereon. Such microparticles are used as a solid support for the affinity reaction involved in a variety of immunoassay formats.

Abstract: A test device and method of determining the presence or concentration of a predetermined ion, such as a cation of medical interest, like sodium, potassium, calcium, magnesium or lithium, in an aqueous test sample are disclosed. The test device includes a test pad comprising a hydrophilic indicator reagent composition capable of interacting with a predetermined ion, or electrolyte, to produce a detectable or measurable response. The hydrophilic indicator reagent composition consists essentially of a hydrophobic ion specific ionophore, a hydrophobic reporter substance, and a stabilizer polymer such as gelatin. The hydrophilic indicator reagent composition, either as a film or layer, or after incorporation into a suitable carrier matrix, provides a test pad of sufficient sensitivity to the predetermined ion to achieve an accurate and trustworthy electrolyte assay of an aqueous test sample, such as plasma or serum, by a dry phase test strip assay.

Abstract: The invention concerns a method for the detection of an analyte in a sample liquid by an enzyme-immunoassay in which an enzyme-labelled compound is partitioned between a solid and a liquid phase and the amount of enzyme label in the liquid phase outside the solid phase is determined as a measure of the concentration of the analyte. The measurement is carried out in a non-porous molding having the liquid phase contained therein in contact with the solid phase. The method is particularly suitable for carrying out in a cuvette which can be filled via the porous matrix or on a test strip having a space in contact with the solid phase.

Abstract: The present invention provides a method for selecting from among many monoclonal antibodies capable of binding to a surface antigen on a tumor cell, the antibody which also can internalize into the cell and exert an appropriate molecular effect on the level of gene regulation in the tumor cell. Such antibodies can most effectively be employed to damage the tumor cell.

Abstract: Disclosed is a method of stimulating an immune response by using a hapten. Haptens are adhered onto a solid phase support to form a complex. This complex can stimulate an immune response of an animal and the animal's lymphocytes. The solid phase supports usable in the method preferably are membranes, latex particles or microparticle beads of hydrophilic cellulose mixed ester, nitrocellulose, cellulose acetate, nylon, polyvinylidone, vinylbenzyl chloromethyl styrene, polyacrolein, a ahydrophobic, polytetrafluoroethylene, polystyrene and silica gel.

Abstract: A porous carrier containing an immobilized biologically active material is prepared in which a relatively large amount of an enzyme or an antibody has been immobilized in a manner that produces a low diffusion resistance toward reagents and products. The porous carrier is produced by fixing enzymes or antibodies within internal micropores of the carrier and mechanically compressing the carrier to a final thickness which is in the range of about 0.20 to 0.80 times the uncompressed carrier thickness. The compressed carrier may have a density about 1.25 to about 5.0 times the density of the carrier before compressing. Surprisingly, the compressed carrier exhibits less diffusion resistance to specific reagents and products than would an uncompressed carrier. A preferred porous carrier is a semi-permeable membrane made from synthetic polymers, such as polyvinylidine difluoride.

Abstract: A semi-automated biological sample analyzer and subsystems are provided to simultaneously perform a plurality of enzyme immunoassays for human IgE class antibodies specific to a panel of preselected allergens in each of a plurality of biological samples. A carousel is provided to position and hold a plurality of reaction cartridges. Each reaction cartridge includes a plurality of isolated test sites formed in a two dimensional array in a solid phase binding layer contained within a reaction well which is adapted to contain a biological sample to be assayed. The carousel and cartridges contain structures which cooperate to precisely position the cartridges in each of three separate dimensions so that each cartridge is positioned uniformly. An optical reader operating on a principle of diffuse reflectance is provided to read the results of the assays from each test site of each cartridge.

Abstract: The invention provides a means for attaching a label, support or bioactive agent to a protein with an exopeptidase at a site that is remote from the active site of the protein. More specifically the invention is directed to a method for the attachment of an amino acid, amine and alcohol nucleophile to the carboxyl terminus of a protein. In one embodiment, a labeled nucleophile is attached to a protein such as an antibody. In other embodiments, the invention is directed to a method for the attachment of a protein to an immobilization support and to a method for the attachment of a bioactive agent to a protein.

Abstract: An immuno active substance immobilized on a carrier and stabilized by immersing the carrier in a solution of at least one of sugars and proteins can be used for measuring a physiologically active substance even after stored for a long period of time. A preferred embodiment of the invention uses a synergistic mixture of a sugar and a protein as the stabilizing agents.

Abstract: Biomolecules such as a ligand or binder for the ligand are securely but reversibly attached to a perfluorocarbon carrier with a water soluble polymer, a perfluorocarbon anchoring group and optionally a linker group. The order of steps for carrying out the attachment can vary. For example, the biomolecule is covalently attached to the polymer followed by covalently attaching the anchoring group and attaching the resultant product to the carrier. Alternatively, the anchoring group is covalently attached to the polymer followed by attaching the resultant product to the carrier and then covalently attaching a biomolecule to the polymer. The polymer may be starch, dextran, agarose, polyethylene glycol or polyvinyl alcohol. An attached ligand or binder for the ligand is useful in affinity separations and immunoassays.

Abstract: A phosphazene polymer for immobilizing biologically active substances such as enzymes is prepared that does not lower activity originally possessed by the biologically active substance and does not contain a functionality which can adsorb undesired substances. The polymer has organic radicals having a functional group capable of binding a biologically active substance and organic radicals which are non-reactive and hydrophilic. The non-reactive and hydrophilic organic radicals are preferably prepared by reacting a side chain of the polymer having a primary amino group with formaldehyde or by diazotizing the primary amino group followed by hydrolysis to form a hydroxyl group. A biologically active substance immobilized on the polymer can be used to separate a substance that has affinity for the immobilized biologically active substance.

Abstract: A specific binding pair is bound to an insoluble carrier for use in determining an analyte such as in an immunoassay. The carrier is coated with a first polymer containing a protein polymer having a molecular weight of at least about 20,000 and molecules of a first member of a specific binding pair. A second polymer containing a second member of the specific binding pair is bound to the first member on the carrier by binding of the first and second members of the specific binding pair. The first polymer is preferably more hydrophobic than the second polymer. The protein polymer can be prepared by cross-linking hydrophobic protein molecules of 10,000 to 700,000 molecular weight with a bifunctional or polyfunctional compound to obtain a protein polymer of 200,000 to 20,000,000 molecular weight. The second polymer can be the second member of the specific binding pair or the second member cross-linked with a linker or the second member cross-linked to a hydrophobic protein.

Abstract: Apparatus and methods are provided for the detection of analytes. A polyunsaturated polymerized lipid layer is employed, which is anisotropic, has a member of a specific binding pair bound to an end of the lipids, and whose optical characteristics are modified upon complex formation between the specific binding pair member and its complementary member. By providing for polarized light, linear and/or circular, one can detect the presence of complex formation by the change in the optical characteristics of the film. Polarizers, analyzers, and wave plates are employed for providing for a light signal which can be analyzed and related to the presence of an analyte in a sample.

Abstract: A modified solid carrier is used to covalently immobilize biomolecules such as proteins. The carrier is based on well-known matrix materials modified to have covalently bound functional groups of formula I ##STR1## that are suitable for covalent immobilization, where A is a spacer group; X is O, S, or NH and n is 0 or 1. The modified solid carrier is prepared by reacting ammonia with glycidyl groups of a carrier to form .alpha.-hydroxy-.beta.-amino groups, reacting these groups with 2,4,6-trichloro-s-triazine to form an N-triazinyl group-containing carrier, reacting this carrier with ammonia and reacting the resultant carrier with 2,4,6-trichloro-s-triazine.

Abstract: An immunochromatography which comprises chromatographically moving a sample together with or followed by labelling fine particles in a chromatographic medium having at least one reaction site having immobilized thereat a reagent bindable to a substance to be detected in a sample, to contact the above sample and the labelling fine particles with the above reaction site, and detecting the substance to be detected by use of the phenomenon that when the above substance to be detected is present in the sample the labelling fine particles are specifically bound to the above immobilized reagent via the substance to be detected at the above reaction site, to thereby capture the substance to be detected on the chromatographic medium, characterized in that the above labelling fine particles are sensitized dyed particles obtained by sensitizing, with a material bindable to the above substance to be detected, labelling dyed particles obtained by dyeing latex particles of a synthetic high polymer, said labelling dyed part

Abstract: Polyacrylonitrile is chemically modified with HX (Cl, Br, I, CF.sub.3 SO.sub.3 H) to produce a polymer with readily replaceable X groups. The modified polyacrylonitrile is useful as an immobilization substrate for, e.g.

Abstract: Enzyme electrodes having a surface coated with a film. The film is formed from materials in which a redox enzyme is covalently bonded to a three dimensional molecular structure. The molecular structure is of the class having multiple redox centers, for example, a crosslinked redox polymer.

Abstract: Graft copolymers and processes for the preparation thereof are provided. The copolymers comprise a base polymer having grafted thereto a monomeric 2-alkenyl azlactone. The surface properties of the graft copolymers can be modified by binding thereto nucleophilic reagents comprising further functional groups with desired properties. Further, the amount of azlactone available at the surface of a graft copolymer for binding to such nucleophilic reagents can be controlled by selecting a surface against which the graft copolymer is formed. The graft copolymers exhibit desirable thermoplastic, melt flow, and adhesion properties and are particularly useful for immobilizing proteins. Methods of immunoassay based on the immobilization of proteins are also disclosed. Another utility of the graft copolymers involves the compatibilizing of immiscible polymer blends.

Abstract: Specific binding methods are used for diagnostic assays and purification separations whereby the specific binding capture reagent is prepared from copolymers having highly reactive carboxy groups. These groups are extended from the polymer surface with a linking group having from 8 to 50 atoms in the chain and two or more alkylene, arylene, alkylenearylene or arylenealkylene groups. To these reactive groups is attached a biologically active substance such as a protein or oligonucleotide which then participates in the diagnostic assays or purification separation methods.

Abstract: Physiological samples are typed for HLA-B27 by contacting the sample with an antibody which binds to HLA-B7 and is not cross-reactive between HLA-B7 and B27, separating the sample from any complexes which are formed, and then testing the sample for the presence of HLA-B27 with an antibody which is cross-reactive for HLA-B7 and B27 in a STAT test. Particularly, an enzyme conjugate is used which binds to a membrane allowing for the detection of any HLA-B27 bound to the membrane.

Abstract: An improved fiber optic sensor, sensing apparatus, and methods for making optical detections are provided. The fiber optic sensor employs a fiber optic strand to convey light energy, an immobilized polymeric reaction matrix, and at least one controlled release polymeric carrier within said reaction matrix comprising a controlled release polymer material and a releasable reagent formulation able to react with the analyte of interest. The optic sensors and sensor construction have been demonstrated to be both functionally useful and long serving in duration.

Abstract: The invention concerns a method for the determination of a partner in an immunological reaction based on an immunoassay in which one of the reaction partners is present in a solid phase, wherein a polyethylene oxidepolypropylene oxide block copolymer having the formula I ##STR1## is used as the surface-active agent in which a can have a value between 40 and 150 and b a value between 10 and 50, which is characterized in that a hydrophilic block copolymer composition having the formula I is used which in a 1 % aqueous solution (weight/volume) has a surface tension of at least 45 mN/m and in which the average molar ratio of ethylene oxide groups to propylene oxide groups (2a/b) in the composition is at least 5.8. In addition the invention comprises a reagent for carrying out the above method.

Abstract: A method and device for testing for the presence of substances such as drugs in body fluids while simultaneously positively identifying the test subject. The device comprises an absorbent pad and a membrane mounted to the absorbent pad containing a plurality of separated areas provided with different immobilized ligand having a specific receptor site for capture or rejection of specific antigens produced by different predetermined drugs.

Abstract: Detecting an immunoreactant in a liquid sample, by:mixing the liquid sample with an excess of a complementary immunoreactant capable of specifically binding to the immunoreactant to allow an immunoreaction to take place, in which the complementary immunoreactant is immobilized on insoluble carrier particles and labeled with an electrochemiluminescent substance that emits an electrochemiluminescent light by electrolytic oxidation in the presence of activated oxygen,applying an electric voltage to a pair of electrodes between which the mixture obtained above is placed, in the presence of activated oxygen to allow electrochemiluminescence to take place;measuring the emission of the electrochemiluminescent light; andcorrelating the presence of the immunoreactant with the amount of measured electrochemiluminescent light, is a highly accurate method, because the rate of change of the emission of luminescent light as a function of immunoreactant concentration in the sample is high.

Abstract: An analytical test device for competition assay for particular non-protein antigens, such as antigens representing drugs of abuse, is disclosed. The analytical test device is a test kit housing having an opening for introduction of a body fluid sample and a flow path for the body fluid sample. A supply of microscopic colored latex particles is adjacent to the opening along the flow path. A chromatographic membrane support is within the test kit housing for exposing the colored latex particles to the body fluid sample. When non-protein antigens are not present in the body fluid specimen, the colored latex particles accumulate at a predetermined site on the chromatographic membrane by complexing of antibodies on the colored latex particles to a drug conjugate probe on the membrane support to leave a visually perceptible colored mark of the same color as the colored latex particles.

Abstract: A method of high sensitivity immunoassay characterized by inclusion of processes (A), (B), (C) and (D) described below.Process (A): A process of binding of a solid carrier and a complex comprising the specific antibody or antigenic substance to be assayed in the test solution and one or more active components.Process (B): A process of dissociating said complex from the solid carrier.Process (C): A process of binding this complex to another solid carrier.Process (D): A process of assay for the complex on the solid carrier mentioned in the description of process (C) above.Permitting rapid, high sensitive immunoassay irrespective of whether the subject of assay is an antibody or an antigen, the method of the present invention is very useful for quick diagnosis of various diseases.

Abstract: A method of assay for antigen comprising the following sequential steps (A), (B), (C) and (D):(A): the antigen to be assayed in a subject solution is bound with a functional group or marker to form a modified antigen;(B): the modified antigen is bound to a carrier via an antibody against the antigen, and then the carrier is separated from the subject solution;(C): Either (a) or (b):(a) the modified antigen is dissociated from the carrier; or(b) the modified antigen-antibody complex comprising the modified antigen and the antibody against the antigen is dissociated from the carrier; and(D): the modified antigen or modified antigen-antibody complex of Step (C) is assayed.

Abstract: Test carrier for the analytical determination of a constituent of a sample fluid by a specific binding reaction between two binding partners having biological affinity. A plurality of test layers is so disposed that they are wetted successively by the fluid and form a fluid transport path, in which one of the test layers is a fixing layer (18) which is a porous carrier matrix. The first of the two binding partners is fixed to the latter. The fluid containing the second binding partner flows through the fixing layer (18), at right angles to its surface, on the test carrier (10).A largely complete binding reaction in an extraordinarily short time is achieved during the flow through the preferably very thin fixing layer (18) by the fact that a microporous plastics layer with a pore size P of at least 0.

Abstract: The performance of double receptor, specific binding assays is improved by use of a receptor complex having the structureA.sub.BL (BL).sub.n A.sub.1wherein BL is a binding ligand, A.sub.BL is a receptor specific for binding ligand, A.sub.1 is a receptor, BL is covalently bonded to A.sub.1 and A.sub.BL is reversibly bonded to BL. Generally A.sub.BL is absorbed onto an insoluble surface and A.sub.1 is an antibody to the substance being assayed. The complex has particular utility in coated tube and rechargeable radioimmunoassay systems.