Abstract: Novel magnetic assay methods and systems. According to a preferred embodiment, a chromatographic medium, which preferably comprises a test strip, is provided that is designed to be contacted with a test solution having activated magnetic particles such that the solution flows bilaterally thereacross. A magnetic field, generated by a magnet or electromagnet, is selectively applied to the medium which causes the charged particles to become substantially bound at a site on the medium specified by the position of the magnet, to thus form a captured line or zone. In one preferred embodiment, the magnetic field is applied at the site on the medium at which the test solution is contacted. The degree of magnetic force applied to the membrane may be selectively adjusted to vary the width or surface area of the capture line or zone.

Abstract: Antibodies and methods are described for the detection and quantitation of cardiac specific troponin I in samples. Cardiac-specific troponin isoforms exist in various forms in the blood, including free and complexed forms. By selecting antibodies that are insensitive and/or sensitive to these various forms, the present invention can provide immunoassays that more accurately reflect the clinical state of an individual. These described antibodies and methods can be used for providing indicators of myocardial infarction and other cardiac pathologies.

Abstract: A method is disclosed for analyzing a biological sample by antibody profiling for identifying forensic samples or for detecting the presence of an analyte. In an illustrative embodiment of the invention, the analyte is a drug, such as marijuana, cocaine, methamphetamine, methyltestosterone, or mesterolone. The method involves attaching antigens to the surface of a solid support in a preselected pattern to form an array wherein the locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to antigens in the array, thereby forming immune complexes; washing away antibodies that do form immune complexes; and detecting the immune complexes, thereby forming an antibody profile. Forensic samples are identified by comparing a sample from an unknown source with a sample from a known source.

Abstract: A method to determine the presence or absence of Streptococcus Group A antigen in a sample, comprising the following steps: extracting the antigen from the sample in an assay chamber with two or less extraction reagents, wherein the two reagents may be added to the assay chamber in no particular sequence; introducing a lateral flow immunochromatographic assay device into the extraction reagents containing the extracted antigen without further addition of reagents or manipulation of the sample; forming an antigen-indicator labeling reagent complex; and determining the presence or absence of the antigen in the sample by the presence or absence of a signal formed by the binding of the antigen-indicator labeling reagent complex to an indicator capture reagent specific for said antigen-indicator labeling reagent complex.

Abstract: The invention relates to a method for determining the conformational state of a protein, comprising the steps of: a) providing a first binding partner which is capable of binding to the protein in a manner dependent on the conformational state of the protein and which generates a signal in a manner dependent on the binding of the first binding partner to the protein; and b) contacting the protein with the first binding partner and determining the conformational state of the protein by assessing the labelling of the protein by the binding of the first binding partner.

Abstract: The invention relates to a method for detection of an analyte in a test sample by a specific binding reaction among the analyte, a specific binding partner for the analyte, and an (immuno)reactant provided with a label, characterized in that the label is a lanthanide ion-ligand complex wherein the lanthanide ion is neodymium(III) ion (Nd3+), ytterbium(III) ion (Yb3+), or erbium(III) ion (Er3+) and the ligand comprises or is in contact with a sensitizing moiety which absorbs in the 400-1000 nm region, and preferably in the 400-800 nm region.

Abstract: Methods of detecting antibodies to one or more glycosphingolipid(s) of interest in a sample are disclosed which comprise using a solid-phase reactant having carbonyl groups attached theron, and the glycosphingolipid(s) of interest linked to the solid-phase reactant by an amide bond between an amino group of the glycosphingolipid of interest and a carbonyl group attached to the solid-phase reactant. The methods of detecting antibodies to glycosphingolipid(s) of interest can be used in methods of diagnosing autoimmune diseases in an individual.

Abstract: Immunoassay methods and apparatus are provided which utilize flow cytometry, coated latex microspheres, and fluorochrome labeled antibodies, to simultaneously detect the presence and amount of one or more analytes in a sample. Beads of several different sizes, colors or shapes, each bead are coated with a different analyte, for the simultaneous detection of one or more analytes and of cell components. The invention is also directed to platelet Ig positive control reagents and assays which provide for the setting of the fluorescence positive region for each patient. The platelet control is sized to fit between the platelets and red cells and thus making it ideal as a true biological control.

Abstract: The invention relates to a method of evaluating the immunological status of a subject comprising the steps of 1) determining the content of an antibody in a liquid sample from the subject using an immunoassay, wherein the reaction between the antibody of the sample and a ligand in the form of an antigen, an antibody or a hapten, the ligand being directed to the Fab region of the sample antibody, is carried out in the presence of other constituents of the sample to obtain a measurement 1, 2) determining the content of an antibody in the liquid sample using an immunoassay, wherein the reaction between the antibody of the sample and a ligand in the form of an antigen, an antibody or a hapten, the ligand being directed to the Fab region of the sample antibody, is carried out in the absence of other constituents of the sample to obtain a measurement 2, and 3) interrelating measurements 1 and 2 to express the interference and using the interference as a parameter for evaluating the immunological status of the subje

Abstract: Assay systems and specialized antibodies for the detection and quantitation of troponin I and troponin T in body fluids as an indicator of myocardial infarction. Since troponin I and T exist in various conformations in the blood, the ratios of the monomeric troponin I an T and the binary and ternary complexes, as well as which form of troponin present in the blood, may be related to the metabolic state of the heart. Disclosed is a system to determine the presence of a troponin form or a group of troponin forms in a sample of whole blood, serum or plasma. Disclosed is a stabilized composition of troponin; the stabilized composition can comprise a stabilized composition of troponin I, wherein the troponin I is oxidized, the troponin I can be unbound or the troponin I can be in a complex. Disclosed is a method for improving the recovery of troponin I or T from a surface used in immunoassays.

Abstract: Immunoassay methods and apparatus are provided which utilize flow cytometry, coated latex microspheres, and fluorochrome labeled antibodies, to simultaneously detect the presence and amount of one or more analytes in a sample. By combining FALS and fluorescence, it is practical to use beads of several different sizes, colors or shapes, each bead coated with a different analyte, for the simultaneous detection of one or more analytes and of cell components such as platelets in a sample.

Abstract: Methods and reagents for rapid purification and/or identification of particles in a liquid sample are described. The technique uses centrifugation to concentrate particles against a slanted surface having an agent specifically binding to the particles. This method is applicable for the rapid identification of viruses and other difficult or impossible to culture microorganisms without replication or amplification of the microorganism.

Abstract: A method for analyzing blood enables one to isolate, detect, enumerate and confirm under magnification the presence of target cells which have expressed surface epitopes that indicate intracellular infection by various viruses or other infectious agents, and also cells which have expressed surface epitopes that indicate the presence of non-infectious medical conditions. The analysis involves the examination of cells in the blood sample for the presence or absence of particular surface epitopes while the blood sample is disposed in a centrifuged blood sampling container. The epitopic analysis for the presence or absence of infected cells, or cells which indicate the presence of non-infectious medical conditions relies on the detection of known target expressed epitopes. The target epitopes on the target cell types are epitopes which are also known to be absent on normal circulating cells in the blood.

Abstract: The invention relates to a method for detecting specific target-cells in a simple and time saving way, using paramagnetic particles, antibodies recognizing the Fc portions of target-cell associating antibodies and target-cell associating antibodies directed to specific antigen determinants in the target-cell membranes. Incubation of the cell suspension with a mild detergent and/or second set of antibodies or antibody fragments, prelabeled or not with fluorescent agents, metallocolloids, radioisotopes, biotincomplexes or certain enzymes allowing visualization, with dramatically increase the specificity of the method. The method can further be used for isolation of the target-cells by magnetic field application and kit for performing the method according to the invention is described.

Abstract: A family of cDNA sequences derived from hepatitis C virus (HCV) are provided. These sequences encode antigens which react immunologically with antibodies present in individuals with non-A non-B hepatitis (NANBH), but which are absent from individuals infected with hepatitis A virus, or hepatitis B virus, and also are absent in control individuals. The HCV cDNA sequences lack substantial homology to the sequences of hepatitis delta virus (HDV) and HBV. A comparison of the sequences of amino acids encoded in the HCV cDNA with the sequences of Flaviviruses indicates that HCV may be related to the Flaviviruses. The HCV cDNA sequences and the polypeptides encoded therein are useful as reagents for the detection and therapy of HCV. The reagents provided in the invention are also useful for the isolation of NANBH agent(s), for the propagation of these agents in tissue culture, and for the screening of antiviral agents for HCV.

Abstract: The present invention recognizes that separation of components of a sample facilitate, and are often necessary for, sample analysis. Dielectrophoretic separation provides an efficient, reliable, nondisruptive, and automatable method for the separation of moieties in a sample based on their dielectric properties. The present invention provides compositions and methods for enhancing the dielectrophoretic separation of one or more moieties in a sample. A first aspect of the present invention is a solution that when mixed with a sample, modifies at least one dielectric property of one or more components of the sample and has a conductivity such that one or more moieties of the sample can be separated using dielectrophoresis. Such solutions can be used in the analysis of samples on chips, and can be used in methods that use binding partners, including microparticles that can be translocated by dielectrophoretic forces, traveling-wave dielectrophoretic forces or magnetic forces.

Abstract: The present invention is directed to methods for analyzing one or more fluid samples for the presence, amount or identity of one or more analytes optionally present in said samples, which uses a device having one or more round wells with a fixed diameter, the wells exposing a substrate of a specific thickness, whereby the substrate has oriented through going channels, in the area of the substrate exposed in the well is provided with at least one binding substance specific for a least one of said analytes. Using the device the sample fluid is forced to pass through the channels in the substrate from the upper side of the substrate to the lower side of the substrate and back at least one time, under conditions that are favorable to a reaction between any analyte present in the sample and the binding substances.

Abstract: The invention relates to a capillary electrophoresis-based method of screening complex materials for any unidentified affinity ligand that binds to a target of interest. The method subjects a plug of a mixture of the target and a complex material sample, and a separate plug of a known, tight-binding competitive ligand, to capillary electrophoresis under conditions optimized to allow mingling of the two plugs during the capillary electrophoresis run. Preferably, migration of the competitive ligand is tracked.

Abstract: The present invention relates to a kit for determining feline blood type, wherein the kit includes a mixture comprised of a first monoclonal antibody and a second monoclonal antibody, wherein both antibodies recognize feline blood group specific A antigens. The present invention also relates to a method for determining feline blood type, wherein the method utilizes two distinct monoclonal antibodies, which recognize feline blood group specific A antigens.

Abstract: A method of single parameter and multiparameter characterizing of cells, particularly immunophenotyping of cells, is provided. The method preferably uses antibody coated microspheres which are adapted to bind to specific types of cells. One or more sets of coated microspheres are added simultaneously or sequentially to a suspension of cells and bind the cells they are adapted to bind. Cells may bind to one or more microspheres. The suspension is then filtered to trap bead-cell complexes. The complexes are preferably stained and then examined to characterize the cells, preferably the cells bound to the microspheres. A kit and apparatus for performing the method are also provided.

Abstract: The present invention describes a method for the binding of pathogenic microorganisms and their toxic proteins with ligands that have been covalently tethered at some distance from the surface of a substrate: distances of at least fifteen Å are required for microorganism binding ligand tethers and at least six Å are required for protein binding ligand tethers. The ligands described herein include heme compounds, siderophores, polysaccharides, and peptides specific for toxic proteins, outer membrane proteins and conjugated lipids. Non-binding components of the solution to be analyzed are separated from the bound fraction and binding is confirmed by detection of the analyte via microscopy, fluorescence, epifluorescence, luminescence, phosphorescence, radioactivity, or optical absorbance. By patterning numerous ligands in an array on a substrate surface it is possible to taxonomically identify the microorganism by analysis of the binding pattern of the sample to the array.

Abstract: Methods for detecting anti-lipidic particles antibodies and lipidic particles in cellular membranes for the diagnosis of diseases associated to the antiphospholipid syndrome are disclosed. Kits or sets to put these methods of diagnosis into practice are also disclosed. Methods for the therapeutically treatment of diseases associated to the antiphospholipid syndrome are disclosed as well. In addition, methods for the detection of the diverse physiologic states of cells, and those kits useful for this are also disclosed.

Abstract: The present invention relates to an immunoassay and an apparatus for the same. A method of the present invention comprises following processes: (1) an analyte is labeled to detect antigen-antibody reaction, (2) the magnetic material label is magnetized by a magnetic field, (3) the magnetized magnetic material label detected by a SQUID which detect a magnetic field having right angle to the magnetic field. At the same time, the present invention contains an apparatus to execute the method provided by the present invention. The apparatus comprises a magnetic field generation means that generates a magnetic field to magnetize the labels. The apparatus comprises a SQUID that measures magnetic field.

Abstract: An immunological test kit suitable for the rapid detection of ciguatoxin and related low molecular weight lipid polyether marine toxins in fish tissues in the field, home or laboratory. The test procedure utilizes a synthetic membrane laminated onto one end of a solid plastic stick, which is immersed into alcohol with a piece of fish tissue. The membrane is then removed and dried thoroughly, then placed in the suspension of mixed colored beads coated with anti-ciguatoxin. The membrane is then rinsed in water and the intensity of the color compared with a standard range of colors formed (0-3+). The color intensity is proportional to the concentration of toxin in the piece of tissue. The kit includes the synthetic membrane on a plastic stick, a suspension of mixed colored beads coated with anti-ciguatoxin antibody, testing instruments, and a supply of solvent.

Abstract: A method of making a high efficiency magnetic sensor for determining the presence or amount of an analyte in a test sample. The method typically includes providing a sensing device with a magnetic sensing element, exposing the sensing device to a fluid test medium suspected of containing an analyte and monitoring the resistance of the magnetic sensing element to detect any change in the electrical resistance of the magnetic sensing element in response to the immobilization of a magnetizable particle. The magnetic sensing element comprises at least one planar layer of electrically conductive ferromagnetic material having an initial state in which the material has a circular magnetic moment within the plane of the layer, a means to immobilize a magnetizable particle at a point along an axis that is perpendicular to the plane of the layer and passes through the center of the circular magnetic moment, and a means for detecting the change in the electrical resistance of each magnetic sensing element.

Abstract: Methods are disclosed which separate and identify lipoproteins in biological samples. An ultracentrifuge density gradient is used to separate lipoprotein fractions. The fractions are visualized, resulting in a lipoprotein profile. The fractions can be further analyzed by a wide array of laboratory and clinical methods. The lipoprotein profile can be used in clinical diagnoses and other medical applications.

Abstract: A catcher, having an immunological epitope, is fixed to a detection zone of a spreading layer. A marker, capable of easy detection, has an inmmunological epitope. The marker and bispecific antibodies are soluble so that they can move on the spreading layer. The bispecific antibodies include a first bispecific antibody, having specificity for the detectable material in the fluid sample and the marker, and a second bispecific antibody, having specificity for the detectable material in the fluid sample and the catcher. Pore sizes and particle diameters are set so that the reaction product in which the marking elements and the particles are bonded are caught at a catching section. The concentration of the marking elements and the particles are increased to improve detection sensitivity. The result is an inexpensive and simple detection apparatus being highly-sensitive for the immunological detection of a detectable material, without wasting valuable antibodies.

Abstract: The present invention provides microfluidic devices and methods for using the same. In particular, microfluidic devices of the present invention are useful in conducting a variety of assays and high throughput screening. Microfluidic devices of the present invention include elastomeric components and comprise a main flow channel; a plurality of branch flow channels; a plurality of control channels; and a plurality of valves. Preferably, each of the valves comprises one of the control channels and an elastomeric segment that is deflectable fat into or retractable from the main or branch flow channel upon which the valve operates in response to an actuation force applied to the control channel.

Abstract: Method of producing purified caveolae are described, in which a sample of interest comprising plasma membranes is subjected to an immunoisolation method in which the sample of interest is incubated with an antibody that is specific for caveolin and which binds to caveolin in its native (oligomeric) state, preferably for a brief time period, and caveolae that are bound to the antibody are separated from other materials in the sample of interest. Purified caveolae produced by the methods, and uses for the purified caveolae, are also described.

Abstract: A method for determining and diagnosing inflammatory enteric disease using an immunochromatographic test device having a multiplicity of test zones. The method tests for the presence of at least one enteric pathogen and at least one of certain inflammatory enteric disease markers. The enteric pathogens tested for can be any number of enteric pathogens such as the pathogens E. coli O157, Campylobacter, Salmonella, Listeria, Shigella, and Yersinia. The inflammatory enteric disease markers tested for are fecal lactoferrin, a bacteria marker, a virus marker, and a protozoa marker. Positive results for any one of the pathogens indicates that pathogen as the cause of the inflammatory enteric disease. Positive results for fecal lactoferrin indicate an inflammatory condition of the intestines. Positive results for the bacteria, virus, protozoa markers indicate respectively a bacterial, viral, or protozoan cause of infection as the cause of the disease.

Abstract: Salt sensitivity is measured as a function of the urinary 25-OHD binding activity, which may be evaluated by measuring 25-hydroxyvitamin D binding activity using radiolabeled 25-hydroxyvitamin D3. High binding activity is indicative of salt sensitivity and is an important predictor for development of salt-sensitivity related hypertension.

Abstract: The invention concerns the stabilization and amplification of electrochemiluminescence signals in detection methods.

Abstract: Novel magnetic assay methods and systems. According to a preferred embodiment, a chromatographic medium, which preferably comprises a test strip, is provided that is designed to be contacted with a test solution having activated magnetic particles such that the solution flows bilaterally thereacross. A magnetic field, generated by a magnet or electromagnet, is selectively applied to the medium which causes the charged particles to become substantially bound at a site on the medium specified by the position off the magnet, to thus form a captured line or zone. In one preferred embodiment, the magnetic field is applied at the site on the medium at which the test solution is contacted. The degree of magnetic force applied to the membrane may be selectively adjusted to vary the width or surface area of the capture line or zone.

Abstract: The present invention describes methods and devices for sequencing a polynucleotide by determining subsets of composite subsequences present in nucleic acid subsamples generated from the sample polynucleotide. A hairpin primer interrogates the composite subsequences in a two-step process resulting first in a polymerase extended product whose synthesis identifies the first subsequence of the composite subsequence. The second subsequences are identified by hybridizing the polymerase extended products or amplified products therefrom to an array of capture probes wherein each capture probe is positionally distinguishable from other capture probes. The invention is applicable to the quantitative determination of the presence of nucleic acids in a sample, for identifying differences in the relative abundance of nucleic acids in a mixture of nucleic acids, and generally, to diagnostic aids for the identification of nucleic acids.

Abstract: Approaches are described for separating plasma from whole blood samples and include the use of magnetically attractable particles associated with an agglutinating agent. The magnetically attractable particles bind the cellular components in a whole blood sample. Application of a magnetic field gradient to a container with the blood sample and the magnetically attractable particles draws the particles to the surface of the container near the source of the magnetic field gradient. The plasma can be removed and stored or used for monitoring or detecting analytes in the plasma.

Abstract: A method of single parameter and multiparameter characterizing of cells, particularly immunophenotyping of cells, is provided. The method preferably uses antibody-coated microspheres which are adapted to bind to specific types of cells. One or more sets of coated microspheres are contacted simultaneously or sequentially with a suspension of cells and bind the cells they are adapted to bind to form bead-cell complexes. Cells may bind to one or more microspheres. The bead-cell complexes are then separated from the suspension The complexes are preferably stained and then examined to characterize the cells, preferably the cells bound to the microspheres. A method of quantitating a specific cell type is provided. A kit and apparatus for performing the method are also provided.

Abstract: The invention provides assay methods and kits that in general measure the level of a first analyte in a sample reduced by the level of a second analyte present in the same sample. In one embodiment, where levels of a first analyte from a first source is desirably determined and first analyte in the sample released from a second source is accompanied by proportional co-release of a second analyte, the assay identifies the level of first analyte released only from the first source. For analytes within bodily fluids, the assay can differentiate between elevated levels of analyte specific to the particular physiological or pathological state and elevated levels not specific to the particular state, providing single tests with diagnostic utility.

Abstract: The present invention relates to devices comprising electrosensors containing capture reagents, their preparation thereof, and their use for detecting, preferably, quantitative measurement, of analyte in a liquid sample. In particular, the invention relates to an enzyme electrosensor, e.g., electroimmunosensor, device for electrochemical detection and preferably, real-time measurement, which is suitable for use at point-of-care settings by unskilled personnel.

Abstract: The present invention provides an improved system for detecting the presence or level of an analyte in a sample. In “competition-like” assays of the present invention, a sample including an analyte is mixed with a second ligand to which the analyte binds, and the mixture is exposed to a solid phase containing a first ligand that can compete with the analyte for binding to the second ligand. According to the present invention, the time of exposure of the mixture to the solid phase is limited so that substantially no dissociation of analyte/second ligand complex occurs. The competition-like assays of the present invention are preferably performed with a solid phase containing a substantial excess of first ligand.

Abstract: A method and apparatus for extracting, identifying, and manipulating proteins or peptides from a solution uses paramagnetic beads having a coating with an affinity for the target component. In one embodiment, paramagnetic beads coated with C18 are used to adsorb proteins and peptides. The beads can be used to purify, immobilize and assay antibodies. By cycling the beads, many times greater molar amount of binding partner may be separated from a solution. A magnetic probe is used to capture the beads and transfer the beads to selected processing stages.

Abstract: The present invention relates to novel methods and devices for detecting non-complexed prostate specific antigen (PSA), which can be used either alone or in conjunction with total PSA tests to identify patients having either benign prostatic diseases (BPD), such as benign prostatic hyperplasia, prostatitis, or glandular atrophy or prostatic adenocarcinoma (CAP). In a biological sample, one can find not only non-complexed PSA, but also PSA which has formed a complex with &agr;1-antichymotrypsin (ACT). The present invention removes or precipitates complexed PSA (PSA-ACT) and ACT from a fluid sample, thereby removing any possible interference due to the binding of complexed PSA to assay reagents.

Abstract: Methods of monitoring transporter activity, gradient induced activity, and binding activity in microscale systems, as well as corresponding microscale devices, systems and kits are provided.

Abstract: The present invention involves a method for assaying a substance. The method of the present invention comprises contacting the substance with an assay agent comprising a catalytic agent to associate the substance with the catalytic agent, contacting the resulting associated substance with a label precursor capable of reacting catalytically with the catalytic agent to release the label, and detecting a mass label. The present invention also involves a kit for assaying a substance. The kit of the present invention comprises an assay agent comprising a catalytic agent, and a label precursor capable of reacting catalytically with the catalytic agent to release a mass label.

Abstract: This invention provides novel methods for monitoring urine for type II collagen fragment using a combination of a capture antibody and a detection antibody, such that type II collagen is distinguished from other collagen fragments.

Abstract: The present invention provides a method capable of simultaneous processing of plural test samples for the receptor binding property of a chemical substance, which does not require immobilization of the receptor or a special device, and a reagent to be used for this method. That is a method for assaying the receptor binding property of an assay target substance is provided, the method comprising the steps of (a) competitively reacting a known concentration of a ligand and the assay target substance with a known concentration of the receptor in a solution, (b) measuring, without physically removing the ligand bound with the receptor prior to the assay, the amount of a free ligand in the solution using one or more antibodies against the ligand, and (c) determining the receptor binding property of the assay target substance using the amount of the free ligand as an index.

Abstract: The invention relates to (1) pressure-mediated dissociation of an analyte complexed with an endogenous binding partner to enable detection of a complex formed from the analyte and an exogenous binding factor, (2) pressure-mediated association of an analyte and an exogenous binding partner to enable more rapid and/or more sensitive detection of an analyte, and (3) pressure-mediated association and dissociation of biomolecular complexes to enable separation of one biomolecule from a complex mixture. Pressure can be used to improve assays by dissociating endogenous analyte complexes and improving assay speed and sensitivity by associating the analyte molecules with exogenously supplied binding partners. Pressure can also be used to improve the separation of compounds from contaminated mixtures.

Abstract: An immunochemical method for the determination of antibodies which are specific for an antigen and are of one of the immunoglobulin classes: A, M, D or E in a fluid, with this fluid being contacted with a solid phase to which the antibodies against this immunoglobulin class, or a fragment of an antibody of this type, are bound, which results in the immunoglobulin of this class being bound to this solid phase, and this solid phase being contacted with the antigen, which carries a labeling means where appropriate, and with a labeled antibody or a labeled fragment of an antibody against the antigen if the antigen is unlabeled and determination, from the amount of labeling means which is bound to the solid phase, of the amount of these antibodies which are specific for an antigen and are one of the immunoglobulin classes, which comprises the solid phase being simultaneously in contact with the fluid containing the antibody which is to be determined and with the antigen, which is labeled where appropriate, there b

Abstract: An immunoassay of a liquid biological specimen for a specific analyte is conducted by forming a test sample by contacting the specimen with: (1) a binding substance of a ligand, antiligand or receptor capable of binding the analyte and (2) a detector substance of a colloidal gold or silver labeled ligand or antiligand to form a test sample. The test sample is applied by flowing onto a defined zone of an insoluble porous support film having a pore size impassable to a complex formed between the analyte, if present, with the binding substance and the detector substance, but passable to the binding substance and detector substance while remaining uncomplexed in the absence of the desired analyte. If the analyte is present in the test specimen, the detector substance binds with the analyte and the binding substance to form a visually inspectable complex on the surface of the porous support film.

Abstract: Compositions and methods are disclosed which enhance the microscopic observation and analysis of biological entities such as cells, bacteria and viruses by eliminating interfering magnetic clusters created by naturally occurring aggregators of colloidal magnetic particles. Additionally means for significantly enhancing the magnetic isolation of low antigen density target cells from biological samples are disclosed.

Abstract: Apparatus and methods are disclosed which facilitate immobilization of magnetically labelled particulate entities, e.g., cells, preferably in a defined pattern, on a collection surface via binding between specific binding pair members, as an aid to particle analysis.