Abstract: An image analysis system is used for the quantitation of nuclear proteins in cell populations. Particularly, the hormonal receptor content of fine needle aspirates of human breast carcinomas are evaluated. Estrogen or progesterone receptors are amplified and visualized in the specimen by a staining technique of the immunoperoxidase type. Monoclonal antibodies specific against the receptor are attached to the receptor sites and are then amplified by a bridging antibody which attaches to the monoclonal antibody and a peroxidase-antiperoxidase complex. A chromagen, diaminobenzidine is combined with the complex and treated with hydrogen peroxide to react with the peroxidase forming an insoluble brown precipitate which marks the receptor sites for optical identification. The specimen is then counterstained with another chromagen, methyl green which is specific to the nucleus of each cell.

Abstract: Am improved device and method for analyte assay in liquid samples, wherein a porous membrane with an immobilized receptor which is capable of directly or indirectly binding to the analyte is separated from a body of absorbent material capable of absorbing the liquid sample by a septum capable of substantially separating the porous membrane from the absorbent body while substantially directing the flow of the liquid sample from the porous membrane to the absorbent body.

Abstract: A chromatic test device for the performance of immuno- or chemical assays wherein a unitary planar fibrous filter body incorporates a sample application zone, a separation zone and a reaction zone and the application zone is in fluid communication with a first absorbent and the reaction zone is in fluid communication with a second absorbent to establish bilateral flow of the fluid component of the sample and of the analyte applied to the zones during the performance of an assay.

Abstract: Analytical reagent reaction vessel and method for performing sequential analytical assay procedures to determine an analyte in a liquid test sample. The reaction vessel is in the form of a closed container having a substantially horizontal axis of rotation and incorporated with one or more analytical reagents for performing a desired analytical assay procedure. The reaction vessel is designed to provide free gravitational movement of a liquid test sample disposed therein. The analytical reagents are incorporated into the reaction vessel such that they are contacted with a liquid test sample in a desired order or sequence. A liquid test sample disposed in the reaction vessel is capable of being manipulated therein by rotating the reaction vessel about the horizontal axis wherein the liquid test sample is transported by gravity.

Abstract: There is described a unique instrument system employing a laser, having a polarized and collimated beam of radiation, which is split into a multitude of primary and secondary beams containing the same desirable properties of high collimation and monochromaticity. The secondary beams are used to measure simultaneously multiple antigen-antibody (Ag-Ab) agglutinations reactions involving latex particles.

Abstract: An apparatus and method for performing enzyme-linked immunological sandwich assays (ELISA) by affinity chromatography. Formation of the antibody-antigen-conjugate complex, and the development of a chromatophore indicator take place in a semi-automated, walk-away, fashion. The immunoassay apparatus comprises a chromatography tank, which further comprises a reaction compartment and a plurality of liquid solvent reservoirs, with a first-liquid reservoir being configured higher than a second-liquid reservoir. The apparatus allows automatic sequential and discrete movement of wash solution, followed by a color development solution, with unbound conjugate being substantially washed away from the immunological sandwich complex before the color development solution automatically comes into contact with the immunological complex.

Abstract: A device for carrying out chemical or clinical testing of a liquid sample, for example a urine sample, by a specific binding assay, said device comprising a test compoenent (2) which has a sensitised solid surface (2a) carrying an immobilized component of a specific binding pair relevant to the essay, and a handling piece (1), and characterized in that the test component (2) bearing the sensitized surface (2a) is removably mounted in spaced relationship with a removably mounted accessory component (4) carrying an accessory solid surface (5), and in that there is a space (4a) between the sensitized surface (2a) and the removable accessory component (4) to act as a container for sample liquid, so that when the device is contacted with a sample liquid source or immersed in liquid which is to provide the test sample, liquid of the sample can enter the space (4a) to contact the sensitized surface (2a), and the accessory surface (5) acts to retain and contain sample liquid in contact with the sensitized surface (2a

Abstract: A method for analyzing antigen or antibody contained in a sample by introducing a first end surface of at least one measuring light guide member and a second end surface of at least one reference light guide member in the sample. Each of said measuring and reference light guide members being coated with a protection layer except for said first and second end surfaces and an other end surface of respect light guides. Only on said first end surface of the measuring light guide member being fixed an antigen or antibody which is specifically reactive with the antigen or antibody contained in the sample to effect an antigen-antibody reaction. Photoelectrically detecting optical properties of said first and second end surfaces of the measuring and reference light guide members, respectively, by transmitting light through the meauring and reference light guide members to derive detection signals as a measure of antigen or antibody in the sample.

Abstract: The present invention provides a carrier for coating with immunologically-active material, wherein it consists of an injection molded synthetic resin with a content of adjuvant and additional materials of less than 1% by weight. The present invention also provides a carrier coated with immunologically-active material, wherein the carrier consists of synthetic resin with a content of adjuvant and additional materials of less than 1% by weight.

Abstract: An immunoassay device and a method of performing immunoassay using this immunoassay device are disclosed. The immunoassay device includes a plate substrate having a flat surface, a plurality of adjacent projections projecting on the flat surface of the plate substrate, and a plurality of immunoreaction regions formed by applying and fixing immunoassay reagents to and in flat regions defined by the adjacent projections. The immunoreaction regions are spaced apart from each other and have surface levels equal to or higher than a surface level of the plate substrate. The immunoassay device is used to simultaneously perform various types of immunoassay and requires a simple washing for immunoassay. Specimens do not flow out from the plate or mix with each other, and safe, accurate immunoassay can be performed.

Abstract: Methods and kits are provided for detecting analytes, which can be measured directly or indirectly, by production of an enzymatic product. The enzymatic product reacts with a signal producing reagent bound to a bibulous strip. Various devices are employed for producing a reaction, directly or indirectly, with the analyte and then providing for migration of the product through the bibulous strip with reaction with the reagent to produce a detectable signal. The distance from a pre-determined site to the border of the detectable signal is a quantitative measure of the analyte in the sample.

Abstract: A test strip for analysis of analytes such as antigens, antibodies or polynucleotides employs a chromatographic medium and a solvent capable of transporting reagents and/or sample. Reagents are selected and disposed on the medium such that a labeled (first) reagent arrives at the detection (third) zone only after analyte is immobilized there and non-reactive sample componets have been transported beyond the detection zone. This sequential arrival is accomplished by the relative mobility of the reagent or sample; or by the site relationship of the zones. Preferably, the site relationship of the sample (second) zone and the label (first) zone is such that a plurality of pathways guide the sample and labeled reagent and any subsequent reagents to the detection zone in the recited order. Single and multiple pathway devices are disclosed.

Abstract: Novel methods and devices are provided for detecting analytes, where the sample is placed upstream from a reagent which is a component of a signal-producing system. The detection zone is provided upstream from the sample, where the amount of reagent which becomes bound at two sites is determined and the two values used for an accurate determination of an analyte.

Abstract: A micro-enzyme described immunosorbent assay (microELISA) method is described for detecting small amounts of thymosin alpha.sub.1 in a solution such as serum. The method uses a known amount of an antibody to the thymosin alpha.sub.1 which is reacted with the thymosin alpha.sub.1 in solution to form a first complex. The solution with the first complex and unreacted antibody is then contacted with thymosin alpha.sub.1 bound to a solid phase which quantitatively forms a second complex with the unreacted antibody. The amount of the second complex is determined and correlated with the amount of thymosin alpha.sub.1 of the solution. Thymosin alpha.sub.1 is an important hormone the presence or absence of which is significant clinically.

Abstract: A method and apparatus for conducting specific binding pair assays, such as immunoassays, is described. A porous membrane capable of non-bibulous lateral flow is used as assay substrate; a member of the binding pair is affixed in an indicator zone defined in the substrate. The sample is applied at a position distant from the indicator zone and permitted to flow laterally through the zone; any analyte in the sample is complexed by the affixed specific binding member, and detected. A novel method of detection employs entrapment of observable particle in the complex. Blood is a particularly preferred sample as the red blood cells can be used as the observable particles for detection of the complex.

Abstract: Method for the bioluminescent dosing of enzymes, substrates or enzymatic inhibitors, characterized in that there is used a transparent support made of synthetic plastic material previously treated with a charged hydrophilic substance for the Fixation by adsorption of an enzymatic system containing at least a luciferase. The invention extends to a support of the polystyrene type treated by a charged hydrophilic substance on which an enzymatic system containing at least a luciferase is fixed by adsorption.

Abstract: There is disclosed a filter and a device positioning the filter between an upper and a lower chamber, particularly useful in an immunoassay. The filter and device are improved in that the membrane comprising the filter is overcoated with at least one water-soluble polymer of a type, a molecular weight, and at a dry-solids coverage effective to create for that membrane an induction time at room temperature of at least about 30 seconds and no greater than about 300 seconds, for a liquid head of pressure of about 6 mm of water.

Abstract: An element for analysis of a liquid sample including a capillary containing a fixed reagent in fluid communication with reagent reservoirs and a waste liquid reservoir. A sample introducing means is provided which permits analyte in a sample to interact with the fixed reagent. A labelled reagent is provided which interacts with either the fixed reagent or the analyte in a manner which permits detection of the concentration of analyte in the sample. The capillary, reagent reservoirs, waste liquid reservoir and the sample introducing means are arranged within a common housing so that reagent waste liquid need not be removed from the element.

Abstract: An immunoassay method and apparatus includes the vibration of beads within a cell, the beads having a complex of a substance conjugated with an enzyme as a marker on the surface thereof, and using an optical measurement device to quantatively determine the amount of the marker in the cell. The vibration is provided by including a magnetic material in the beads and causing a magnetic field to move within the cell. The vibrations have at least a component transverse to a measurement direction of the optical measurement device. The movement of the magnetic field in the cell is caused by the reciprocation of a bar having magnets thereon and in a position adjacent to the cell.

Abstract: A novel material and device useful in solid-phase binding assays to determine the presence or amount of an analyte in a test sample, particularly antigens, antibodies, or other ligands or DNA segments. The material and device comprises a reaction site having procedural controls and an analyte binding area capable of being simultaneously contacted by the sample and reagent used in the performance of the assay. The procedural controls and analyte binding areas operate to provide readable results as to the presence or absence of analyte and simultaneously verify the assay procedure and therefore the assay result.

Abstract: An assay apparatus employing total internal reflection of excitation radiation at the interface between a replaceable optically conductive rod or fiber and a surrounding liquid phase of lower index of refraction. Immobilized on the surface of the fiber is a component of a complex formed in an immunological-type specific reaction. A fluorophore that can be excited into fluorescence by the excitation radiation is attached to another component of the complex. The rod is coaxially mounted within a tube that is sized with respect to said rod so that a fluid sample may be introduced into said tube.The rod and tubing are supported in a mounting assembly that is attachable to an optical assembly for transmitting excitation radiation into the proximal end of the rod and receiving fluorescent radiation emitted from the proximal end of the rod. Included in the apparatus is a mounting assembly for centering the rod within tube and for biasing the rod in a first direction against an annular seat.

Abstract: An improved laboratory chamber apparatus capable of carrying out multiple laboratory processes including hybridization, cell growth, and chromatographic separations, among others, includes a low profile base having a minimum volume chamber positioned therein. The chamber includes a selectably removable cover which is capable of providing access to and sealingly closing the hollow chamber. In the preferred embodiment, the cover is disc shaped so as to be able to sealingly engage a side wall of a low profile hollow cylindrical chamber and is insertable into the chamber to an adjustable depth to minimize the chamber volume, while allowing a variation of that volume depending upon the number of filters, membranes, or other accessories placed in the chamber. The hollow cylindrical chamber further includes opposed input and outuput ports, the input port providing for measured input of experimental solutions, wash solutions, etc.

Abstract: A method and apparatus for quantitatively analyzing, in a flowing stream, materials in a biological or chemical sample utilizes immobilized antobodies reversibly precharged with fluorescently labeled antigens. The labeled antigens are competitively displaced by unlabeled antigens in the sample, after the sample antigens have been segregated into zones by a chromatographic device, such as the reverse phase high performance liquid chromatograph. Displaced labeled antigens are measured by a fluorescence detector. A plurality of antibody species may be concurrently utilized, thereby allowing quantification of a plurality of antigens from a single sample.

Abstract: Devices and methods are provided for making a plurality of determinations of the local (site-specific) redox state of a liquid system, by employing a photoresponsive element, which can be independently irradiated at different sites to provide independently detectable signals.

Abstract: The present invention relates to novel dielectric waveguide (i.e., fiber optic) sensors for use in spectrophotometric assays of analytes in fluids. More particularly, the use of these sensors in immunoassays is disclosed.

Abstract: An optical assay apparatus of the type comprising an optic waveguide and a coating sensitized to a specific assay species. The light signal response of the apparatus is enhanced by coupling a resonant metallic medium to the waveguide and to the sensitized coating. To this end, a metal coated transparent buffer layer may be interposed between the waveguide and the sensitized coating. Alternatively, a metallized optically matched grating can be used in place of the buffer layer or the metallic medium can be of particulate form, with each particle having a sensitized coating.In using the optical assay apparatus, the sensitized coating is exposed to a fluid assay sample. A light beam is directed onto the sensitized coating and reflected onto a detector. The detected light is monitored for any change indicating the presence of the specific assay species in the fluid sample.

Abstract: Improved, economical devices for immunoassays employ a reusable syringe or vacuum manifold to withdraw samples through a membrane containing an affinity partner for analyte. The devices can also be adapted to direct blood sampling and to automated assays.

Abstract: A system and method for performing a clinical assay, both including the use of a reaction capsule having a hydrophobic membrane which may be repeatedly wetted and rendered hydrophobic. A pressure differential across the membrane causes liquid flow therethrough to be initiated and the hydrophobic state is then achieved by flowing gas through the membrane. The system includes a turntable supporting a plurality of reaction capsules and eccentric means for agitating the turntable and capsules. The turntable is rotated to position the capsules at various processing stations, including sample introduction, reagent introduction, wash, substrate introduction and read stations. A single cylinder two-inlet valve may be used, one inlet connected to liquid and a second inlet connected to a gas source, to provide both liquid and gas flow through the membrane.

Abstract: A sample device and method for assaying samples containing members of immunological pairs by chemiluminescence include a first chamber wherein antibody-conjugated reagent antigen labelled with a chemiluminescence moiety is displaced from the antibody by sample antigen. The labelled reagent antigen diffuses into a second chamber, wherein the chemiluminescence moiety reacts with cofactors to produce a light emission proportional to the amount of sample antigen present.

Abstract: A method is described for kinetic measurement of enzyme activity bound to a solid matrix which improves both the sensitivity and speed of one immunoassay method. The immunoassay typically consists of reaction of the analyte with two specific antibodies, one fixed to the surface of a polymeric bead or wall of a test tube, the other added in solution and labeled by covalent coupling to an enzyme. By reaction between analyte and both antibodies, the enzyme-labeled antibody becomes fixed to the surface in a quantity proportional to the quantity of the analyte. After washing sufficiently to remove unreacted enzyme-labeled antibody, fixed enzyme activity is measured by incubation with a substrate and measurement of the rate of the reaction catalyzed. Fixation of the enzyme causes the reaction products to be localized near the surface. To measure the concentration of reactant or product repeatedly during the reaction, the solution must be mixed before each measurement, which can interfere with the measurement.

Abstract: A device is disclosed for conducting an assay method. The device comprises a housing, means enclosed in the housing for capturing a member of a specific binding pair in a zone and for allowing liquid to be transported by capillary action away from the zone, one or more self-contained liquid reagents enclosed in the housing for conducting an assay method for the determination of an analyte in the sample, and means in the housing for introducing the sample into the device. Preferably, the self-contained reagents are liquid reagents which are contained in a breakable container. The device of the invention finds use in assay methods for the determination of an analyte in a sample suspected of containing the analyte. Kits for conducting an assay method are also disclosed.

Abstract: Test device and assay for determining analyte wherein tracer and sample may be simultaneously applied to different absorbent material portions both in capillary flow communication with an absorbent material portion having a binder supported thereon in a manner whereby sample contacts binder, prior to any substantial contact between sample and tracer or tracer and binder.

Abstract: A sandwich immunoassay method is disclosed that is useful for the identification of an antigen in biological specimens. The method is comprised of a colloidal gold labeled binder specific for epitopes or receptors of a ligand, nonporous particulate solid phase which have antiligand covalently attached, and which said reagents are combined with the biological specimen or an extract of the biological specimen, and after an appropriate incubation, the said reactant mixture is contacted to a porous film having an exposed surface area of contact no greater than 30 mm.sup.2 to separate and concentrate the particle bound colloidal gold labeled binder from the unbound. The identification of an antigen is determined by the presence of color on the surface of the solid phase particles captured on the surface of the film. A competitive inhibition assay can be also used to identify the presence of a hapten or antigen, in which case the presence of the analyte is determined by the absence of color.

Abstract: Devices and methods are provided for making a plurality of determinations of the local (site-specific) redox state of a liquid system, by employing a photoresponsive element, which can be independently irradiated at different sites to provide independently detectable signals.

Abstract: An assay apparatus employing total internal reflection of excitation radiation at the interface between an optically conductive rod or fiber and a surrounding liquid phase of lower index of refraction. Immobilized on the surface of the fiber is a component of a complex formed in an immunochemical-type reaction; a fluorophore that can be excited into fluorescence by the excitation radiation is attached to another component of the complex. The fiber is coaxially mounted in cantelivered position within a length of tubing, so that the excitation radiation can be launched into the unsupported end of the fiber and the fluorescent radiation tunneling back into the fiber may be observed at the same fiber end.

Abstract: The present invention provides a process for the quantitative determination of free thyroxine (FT.sub.4) in plasma, serum or whole blood by immunological methods, wherein the sample is incubated for at most 10 minutes with a 10 to 2000 fold insufficiency of labelled anti-T.sub.4 antibodies, referred to the molar amount of total T.sub.4 in the sample, then immediately brought together with immobilized excess T.sub.4, again incubated, the phases separated and the label measured in one of the phases.

Abstract: A device is provided for determining the presence of an antigen which comprises a trapping zone, which contains material capable of capturing free flowing enzyme linked antibodies, but not antibodies bound to a transport particle which flows freely through the trapping zone into the substrate zone, and a substrate zone which contains material capable of reacting with enzyme-linked antibodies to produce a reaction which indicates the presence of antibodies. A method of determining the presence of an antigen is provided wherein a sample is mixed with two classes of antibodies which are specific for the antigen being tested for, but which react with different antigen domains, wherein the mixture consists of class one antibodies bound to a transport particle which flows freely through the trapping zone and class two enzyme-linked antibodies which are incapable, unless bound to the transport particles, of flowing freely through the trapping zone.

Abstract: There is disclosed a container for storing a reagent and then for reacting the reagent to produce a signal representative of the presence of an analyte, or of the amount of that analyte. The container is disposable and comprises at least one compartment having an upper portion and a lower portion. The upper portion comprises a stored reagent and means for retaining for observation on an indicator surface a reaction product of such reagent following a reaction of the reagent with a liquid sample. The lower portion includes means for absorbing liquid extracted from the upper portion through the retaining means. The absorbing means is configured with a shape that contacts the confining means only at locations spaced inwardly away from at least two of the side walls of the upper portion, whereby the reaction product of the liquid sample and the reagent is induced to flow into the confining means away from the two side walls to produce a uniform signal.

Abstract: The invention relates to a chromatographic column for separating antigen-antibody complexes from the free antigens not bonded to the antibodies and/or for complete bonding of all marked substances in the immunological determination of antigens or haptens by radio-immunological, luminescence-immunological, fluorescence-immunological or enzyme-immunological determination methods in which a crepe-like tightly rolled filter paper of high degree of purity, in particular of regenerate cellulose, is pressed into a water-proof and water-tight envelope as nonpolar column material. According to the invention the chromatographic upright column comprises an upper reaction portion chargeable from above and a lower separation and measuring portion which are separated from each other by a perforable bottom, the column being fastened from below on the perforable bottom of the column.

Abstract: A method for reducing false positives and to assay background noise in solid phase immunoassays utilizes a matrix coated on a solid support, which matrix contains an effective amount of a noise reduction component and an effective amount of noise balancing component. Optimization of the matrix composition is obtained by measuring parameters for its effectiveness which include sensitivity ratio, noise balance ratio, and signal to noise ratio.

Abstract: An immunoassay device comprising a support which has a substantially planar surface 14 on which is located an array of small, closely-spaced, discrete, antibody coated areas (spots) 17. A cover 16 is spaced from the support surface 14 and is positioned over the array of antibody coated spots 17. The cover is attached to the support surface to provide an enclosed chamber 30. In the cover there is at least one aperture communicating with the interior of the chamber 30 for introducing a liquid sample into the chamber. In addition, there is at least one additional aperture 34 in the cover, which also communicates with the interior of the chamber to allow air to escape upon introduction of the sample into the chamber. When a cell sample is introduced into the chamber it immediately fills the chamber and cells will settle uniformly over the matrix. The antibody-coated spots function as tiny immunoadsorbents for cells bearing antigens recognized by the antibody.

Abstract: A membrane structure useful in filtration and diagnostic tests includes a microporous membrane formed from a biologically inert material, such as a polyamide, and has a coating comprising one or more water-soluble proteins or carbohydrates. None of the proteins and carbohydrates in the coating has a pI greater than about 5. The membrane structure is prepared by contacting the microporous membrane with the appropriate protein or carbohydrate in an amount sufficient to provide a coating over the entire membrane surface without substantially diminishing the porosity of the membrane. The membrane structure is useful in various diagnostic test procedures, such as agglutination assays.

Abstract: A method of detecting biological substances having affinity properties by passing the substance to be detected in a flow over a solid surface to which surface a second substance, to which the substance to be detected shows affinity, is attached, so that the two substances form a complex and give enrichment of the substance to be detected. The enrichment is obtained when the fluid volume passing the active surface is many times larger than the volume in contact with the active surface. A means for detecting biological substances consisting of a flow of a fluid sample of the substance to be detected generated via a pump over a solid surface to which another substance, to which the first substance to be detected shows affinity, is attached, so that a complex is formed of the two substances and gives enrichment of the substance to be detected.

Abstract: A device for the detecting of an individual's Gell-Coombs Types I, II, III and IV immune response reactions to edible substances includes a mixture of an edible substance and a solution of non-toxic aprotic solvent, such as DMSO and water. The solvent acts as a carrier transporting the food beneath the skin. The device holds the mixture against the skin and prevents evaporation of the solution. The method includes the preparation of a plurality of mixtures of different edible substances and a solution of non-toxic aprotic solution, the application of the mixture to the skin of the individual and the holding of the mixture on the skin for a predetermined period of time. The mixture is subsequently removed, and the site is inspected to determine whether a Type I, II, III or IV Gell-Coombs immune response reaction has occurred. Control sites containing the solvent only and a control site containing a food substance which causes the skin to fluoresce upon exposure to an ultraviolet light may also be used.

Abstract: A multizone test device for the determination of analyte from a liquid test medium upon contact with the liquid test medium and a labeled reagent comprising a chemical group having a detectable chemical property. The test device preferably comprises multilayers including a reagent layer incorporated with an immobilized reagent and a detection layer incorporated with an immobilized form of an interactive detection reagent for the labeled reagent. The immobilized reagent in the reagent layer and the labeled reagent comprise specific binding partners which will bind to each other dependent upon the amount of analyte present. Labeled reagent which does not become bound to the immobilized reagent in the reagent layer migrates into the detection layer and interacts with the immobilized interactive detection reagent therein which results in the localized generation of a detectable reaction product which preferably is also immobilized in the detection zone.

Abstract: A multizone test device for the determination of analyte from a liquid test medium upon contact with the liquid test medium and a labeled reagent comprising a chemical group having a detectable physical property. The test device preferably comprises multilayers including a reagent layer incorporated with an immobilized reagent and a detection layer incorporated with an immobilized form of a binding substance for the labeled reagent. The immobilized reagent and the labeled reagent comprise specific binding partners which will bind to each other dependent upon the amount of analyte present. Labeled reagent which does not become bound to the immobilized reagent in the reagent layer migrates into the detection layer and becomes bound to and immobilized by the immobilized binding substance therein.

Abstract: An immunoassay device including one or more reaction chambers, each adapted to receive and retain a volume of test fluid in fluid communication with nonoverlapping first, second, and third reagent-bearing surfaces. To the first surface is reversibly bound an analyte conjugate: analyte component conjugated to one or more components, termed ligand/marker, that serve ligand and marker functions as described herein. Analyte binding partner is immobilized on the second surface, and ligand/marker binding partner is immobilized on the third surface. The reaction chamber is preferably configured to receive and direct the test fluid sequentially past the first second, and third reagent surfaces. In use, analyte conjugate solubilized from the first surface completes with any analyte in the test fluid for analyte binding partner sites on the second surface.

Abstract: A compound is bound to a membrane which is reactive to a component in a fluid sample which is being tested. Under the membrane a porous support is added. The fluid sample suspected of containing a specific component is drawn over the membrane and into the porous support by a piston and cylinder arrangement.

Abstract: Certain reducible aromatic and quinone compounds having bulky groups on the carbamate nitrogen atom have improved stability to light. These compounds are useful in analytical compositions, elements and methods, e.g. for assays of bacterial cells. These compounds have suitable substituents that promote the release of phenalenone or benzphenalenone fluorescent dyes at physiological pH.

Abstract: A method is disclosed for detecting the occurrence of a binding or complex-forming reaction between specific substances by utilizing the binding reaction to complete an electrical circuit, and then measuring a change in the electrical state of this circuit. In a preferred embodiment, a layer of antigen is coated onto a non-conductive base between a pair of electrically conductive layers superposed on the base. Antibodies which react with the foregoing antigen are treated so that they become bound to fine electrically conductive, metallic particles. The electrically conductive particles having antibody bound thereto are then added to the antigen layer deposited on the base and allowed to react therewith. Electrically conductive particles are thereby bound to the base due to the binding reaction between the antigen and antibody to thereby form aggregates of electrically conductive particles which bridge the electrically conductive layers and complete the circuit.