Abstract: An immunoassay element for quantitatively analyzing a macromolecular antigen by determining the change in enzymatic activity caused by a reaction between the macromolecular polymer antigen and an enzyme-labelled antibody. The immunoassay element comprises a substrate layer containing a non-diffusible substrate which forms a diffusible material in the presence of the enzyme, and a reagent layer containing a fragmenting enzyme for further fragmenting the diffusible material into a lower molecular weight product. Also provided is a process for quantitatively analyzing a macromolecular antigen in a sample by the use of the immunoassay element.

Abstract: A particle-enhanced assay for determining an analyte in a test sample in which an additive for reducing non-specific particle aggregation is added in an amount to substantially reduce non-specific aggregation.

Abstract: Methods for assessing immunocompetence, cellular or humoral immunity, antigen exposure, or allergic conditions in an individual by accelerating diagnostic particles into a target skin site in the individual are provided.

Abstract: This invention relates methods for conditioning affinity chromatography resins to decrease leaching of the ligand during purification. The methods involve incubating the resin in a buffered solution of a hydroxyalkylamine compound (e.g., ethanolamine) prior to use of the resin for an affinity purification. The treatment removes unstably bound ligand from the resin.

Abstract: Novel sensor devices composed of a crystalline colloidal array (CCA) polymerized in a hydrogel are disclosed. The hydrogels are characterized as being capable of shrinking and swelling in response to specific stimuli applied thereto. As the hydrogels shrink or swell, the lattice structure of the CCA embedded therein changes, thereby changing the wavelength of light diffracted by the CCA. Thus by monitoring the change in diffracted wavelength, the concentration of a stimulus is determined. The gels can be modified to sense numerous different stimuli. The sensor devices are specific in that they are modified to react with only one species or family of species. These sensors have various applications in areas including, for example, environmental and chemical systems, chemomechanical systems, sensor devices and medical diagnostic tools. Various methods for making and using these devices are also disclosed.

Abstract: An immunochemical assay device comprising a base member, an array disposed on the base member, and at least one assay indicia zone. The array comprises (I) a reservoir pad to receive sample liquid, (ii) a wicking membrane, and (iii) at least one filter zone interposed between the wicking membrane and the reservoir pad. The filter zone being operable to permit passage of any specific immunocomplex to the wicking membrane while impeding passage of larger components.

Abstract: Disclosed are biochips having a high detecting sensitivity with readiness in fabrication of microarray, and a method for fabricating the same, in which a solid support wound with fibers is immersed in a solution containing biomolecules to immobilize the biomolecules onto the fiber, and the individual fibers with the biomolecules immobilized thereon are straightened and arranged. The arranged fibers are embedded with a defined material and cut in a direction perpendicular to the lengthwise arrangement direction of the fibers to obtain thin chips. The chips are placed on a substrate to remove the material used for embedding and thereby remain fibers with the immobilized biomolecules on the substrate. This biochip fabrication method immobilizes a great number of biomolecules onto the fibers having a large surface area to enhance the detection sensitivity and allows production of a great number of substrates with an array of biomolecules immobilized simultaneously.

Abstract: A selective adsorption material, especially suitable for adsorption of biological macromolecules, is described. The, adsorption material comprises a matrix with immobilised ligands, localised to selectively adsorb a predetermined molecule. A process for preparing a selective adsorption material, especially suitable for adsorption of biological macromolecules, is also described. The process is characterised in that a print molecule having at least two separate binding sites is bonded to the corresponding, at least two immobilisable ligands, the ligands are immobilised, and subsequently the print molecule is removed. The selective adsorption material can be used for purification or analysis, especially of biological macromolecules.

Abstract: Compositions and methods of use thereof for capture and detection of selected molecules are described. In one embodiment, a first composition includes a ligand component, such as an antibody coupled to a nucleic acid component. An a preferred embodiment, the nucleic acid is labeled with a fluorescent marker to facilitate detection. Another aspect of the invention is the ligand component bound to a solid support via a complementary nucleic acid component and a linker moiety. The method involves binding the target with the first composition in free solution, then binding the target to the solid support by means of both DNA hybridization and antibody-antigen affinity binding. Unbound molecules are washed away, and then the bound targets are detected by fluorescence detection. Vital stains can also be used to detect viable cells.

Abstract: An agglutination assay method for quantitatively determination of an analyte in a liquid sample using particles bearing an anti-analyte. A non-fluid substance which retains the particles while suppressing the diffusion of the particles therein is used as a medium which is to be a place where the agglutination of the particles takes place. Upon analysis, a solation agent is added to the non-fluid substance medium to increase the fluidity of the non-fluid substance, thereby the particles bearing the anti-analyte can diffuse in the medium to cause the agglutination with the analyte. Preferably, the solation agent is added to the non-fluid medium together with the sample. The non-fluid substance medium containing the particle-labeled anti-analyte can be stored with a higher stability in the dry state. A dry analysis element for enabling such analysis method is also provided.

Abstract: A semiconductor nanoparticle for use in analysis of biological samples is described. This semiconductor nanoparticle is composed of an aminodextran which is bound to at least one nanoparticle of the formula (X Y)n wherein X is selected from the group comprising Cd2+, Hg2+, and Zn2+ and combinations thereof, and Y is selected from the group comprising S2−, Se2− and Te2− and combinations thereof; and n=approximately 50 to 1000. Also provided are methods of making these semiconductor nanoparticles and methods of making conjugates composed of these semiconductor nanoparticles linked to ligands. Also described are uses for the conjugates in a variety of biological assays.

Abstract: Cell based screens for studying drug transport are described and improved methods for the preparation of cell monolayers for use in such screens are disclosed.

Abstract: Methods, compositions and devices for purifying polypeptides and/or proteins using metal loaded ligand bound membranes by metal ion affinity chromatography are described.

Abstract: The present invention provides low molecular weight fluorescent labeling complexes with large wavelength shifts between absorption of one dye in the complex and emission from another dye in the complex. These complexes can be used, for example, for multiparameter fluorescence cell analysis using a single excitation wavelength. The low molecular weight of the complex permits materials labeled with the complex to penetrate cell structures for use as probes. The labeling complexes are synthesized by covalently attaching through linkers at least one cyanine fluorochrome to another low molecular weight fluorochrome to form energy donor-acceptor complexes. Resonance energy transfer from an excited donor to fluorescent acceptor provides wavelength shifts up to 300 nm. The fluorescent labeling complexes preferably contain reactive groups for the labeling of functional groups on target compounds, such as derivatized oxy and deoxy polynucleic acids, antibodies, enzymes, proteins and other materials.

Abstract: The invention concerns a method for the immunological determination of an analyte in a sample using magnetic particles coated with the analyte to be determined or analyte-specific bonding partners and directly detectable non-magnetic particles coated with analyte-specific bonding partners or the analyte to be determined or using a non-magnetic substance which is indirectly detectable, and incubation of the reaction mixture. The method is characterized in that the magnetic particles are subsequently separated from the reaction mixture using a magnetic test strip and the analyte concentration is determined directly.

Abstract: The invention provides monoclonal antibodies which are reactive with fibrin(ogen) degradation products (FDPS) generated by matrix metalloproteinases (MMPs), such as MMP-3, MMP-7, and membrane-type 1, MT1-MMP proteolysis of fibrinogen and cross-linked fibrin (and not plasmin or other proteases). Monoclonal antibodies of the invention include, but are not limited to, H5, F2, 90/2, 90/5, B4, 13, C6, A6, G6, E6, 197-1 and 197-2. This invention also provides methods of using monoclonal antibodies for detection of FDPs generated by proteolysis of fibrin(ogen) by MMPs, such as MMP-3, MMP-7, and MT1-MMP. In addition, the present invention provides methods for diagnosing rheumatoid arthritis, osteoarthritis, and synovitides, as well as angiogenesis, atherosclerosis, renal diseases, malignancy and inflammation.

Abstract: A particle resistant to storage of at least one first and at least one second component, wherein said second component of at least one crosslinkable polymer as a shell at least partially envelops and/or encloses said first component as a core and said first component has at least one ascertainable property, obtainable by reacting said first component with the crosslinkable polymer and subsequently reacting the formed product with a crosslinking agent such that the first component with resistance to storage remains within the second component.

Abstract: The present invention provides a method for immobilizing a polysaccharide (PS) to a solid surface, said polysaccharide having a keto-carboxy group (—C(═O)—COOH) or a ketal or hemiketal group corresponding thereto, e.g. derived from KDO (2-keto-3-deoxy-D-manno-octonic acid)), the method comprising the steps of: (a) forming a covalent bond between the carboxy group of the polysaccharide and a reporter molecule (RM), thereby forming a polysaccharide-reporter molecule conjugate (PS-RM), said reporter molecule comprising a recognition/substrate site (e.g. biotin or an anthraquinone); and (b) immobilizing the polysaccharide-report molecule conjugate by forming a specific bond (e.g. by photocoupling or formation of an affinity pair) between the recognition/substrate site of said reporter molecule and a reception/reagent site of the solid surface. The present invention also provides a solid surface thus obtainable and the use of such solid surfaces for diagnostic purposes, e.g.

Abstract: The invention discloses a method for detecting and/or quantifying a hapten in a homogeneous phase, comprising the following steps: adding a known quantity of a hapten inhibitor complex to the solution containing the hapten to be detected and/or quantified; adding to the solution a quantity of antibodies corresponding to the quantity of the hapten/inhibitor complex; adding to the solution a type C &bgr;-lactamase having an active site for two substrates in antigenic competition in the said active site, the first substrate being a reporter substrate capable of being transformed into a detectable and/or quantifiable product, preferably by visible UV radiation measurement, the second substrate being the hapten/inhibitor complex acting on the hydrolysis rate of the reporter substrate; detecting and/or quantifying the concentration of the product resulting from the transformation of the reporter substrate, the Km constant of the reporter substrate being at least a hundred times higher than the Km constant of the ha

Abstract: Disclosed is a method for the measurement of a cellular process, or for the measurement of the effect of a test compound on a cellular process, in one or more different populations of cells. The method comprises providing separate samples of one or more different populations of cells adhering to support particles, the support particles comprising a scintillant substance and being adapted for cell growth. In one embodiment, different samples of cells are introduced into separate reaction vessels in a fluid medium, together with a reagent labelled with a radioisotope, in the presence or the absence of the test compound, under conditions so as to cause a portion of said radiolabelled reagent to become associated with the cells. In another embodiment, multiparameter analysis may be performed to determine the effect of a test compound on a cellular process using two or more different cell populations present in the same well.

Abstract: A method and apparatus for the physico-chemical encoding of a collection of beaded resin (“beads”) to determine the chemical identity of bead-anchored compounds by in-situ interrogation of individual beads. The present invention provides method and apparatus to implement color-coding strategies in applications and including the ultrahigh-throughput screening of bead-based combinatorial compounds libraries as well as multiplexed diagnostic and environmental testing and other biochemical assays.

Abstract: A general stochastic method for synthesizing random oligomers can be used to synthesize compounds to screen for desired properties. The use of identification tags on the oligomers facilitates identification of oligomers with desired properties.

Abstract: The present invention relates to a kit and an assay method for rapidly and directly detecting a predetermined respiratory syncytial virus-related biological cell in a sample, even when present in an amount of less than about 2000 cells per microliter. In a preferred embodiment, a labeled antibody targets a nucleoprotein or a glycoprotein of RS virus. One may further detect an inflammatory indicator in the sample.

Abstract: A method of measuring the amount of cyclosporin in a sample suspected of containing cyclosporin is disclosed. A method of inactivating interfering cross-reactive material in an assay for measuring the amount of cyclosporin in a sample suspected of containing cyclosporin is also disclosed. Compositions wherein cyclosporin is conjugated to an immunogenic carrier or a label, optionally through a linking group, at an alanine nitrogen atom of the cyclic backbone of cyclosporin are also disclosed. Compositions wherein atiocyclosporin is conjugated, optionally through a linking group, to an immunogenic carrier or a label are also disclosed. Where cyclosporin is conjugated to an immunogenic carrier, the conjugates may be used as immunogens for the preparation of antibodies which are capable of recognizing cyclosporin.

Abstract: A particle resistant to storage of at least one first and at least one second component, wherein

Abstract: A separation medium having a base matrix and matrix-bound groups which exhibit recombinant Protein A containing a cysteine. The groups are of formula: —B—X—rProtein A-cys where B is a bridge which binds to the base matrix and X includes a heteroatom N or S from rProtein A-cys. In a preferred embodiment X is a thioether sulphur and/or a secondary amine (—NH—). An alternative embodiment features a variant of Protein A in which the C-terminal residue is cysteine.

Abstract: Ligand-aminodextran-(phycobiliprotein or tandem dye) conjugates useful for detection of a desired target biological material by providing an enhanced fluorescent signal are described. Also described is a method for a single-measurement quantification of multiple populations of cells based upon the labeling of different pairs of cell populations, each pair containing mutually exclusive cell receptors which are expressed at substantially similar receptor densities with labeled ligands for each receptor. One cell population is labeled with a ligand capable of binding to a first cell surface receptor which ligand is directly conjugated to a fluorescent phycobiliprotein or tandem dye; and a second cell population is labeled with a ligand capable of binding to a second cell surface receptor, which ligand is cross-linked to an aminodextran to a fluorescent phycobiliprotein or tandem dye.

Abstract: The present invention relates to bioassay materials useful for the detection of toxic substances and, more particularly, to packaging materials for food and other products, along with methods for their manufacture and use. The invention provides a unique composite material capable of detecting and identifying multiple biological materials within a single package. The biological material identification system is designed for incorporation into existing types of flexible packaging material such as polyvinylchloride or polyolefin films, and its introduction into the existing packaging infrastructure will require little or no change to present systems or procedures.

Abstract: The present invention relates to bioassay materials useful for the detection of toxic substances and, more particularly, to packaging materials for food and other products, along with methods for their manufacture and use. The invention provides a unique composite material capable of detecting and identifying multiple biological materials within a single package. The biological material identification system is designed for incorporation into existing types of flexible packaging material such as polyvinylchloride or polyolefin films, and its introduction into the existing packaging infrastructure will require little or no change to present systems or procedures.

Abstract: The present invention is directed to novel tricyclic antidepressant drug derivatives synthesized for covalent attachment to proteins or polypeptide antigens for use in the preparation of antibodies or receptors to tricyclic antidepressant drugs and tricyclic antidepressant metabolites. The new derivatives are characterized by a saturated double bond on the amitriptyline portion of the molecule and are represented by the structure where R1 is a saturated or unsaturated, substituted or unsubstituted, straight or branched chain of 0-10 carbon or heteroatoms, X is a linker group consisting of 0-2 substituted or unsubstituted aromatic rings, and Y is an activated ester or NH—Z, where Z is a poly(amino acid).

Abstract: The invention concerns a novel method for purifying and quantifying viral particles. More particularly, the invention concerns a method for purifying and quantifying adenovirus by ion-exchange chromatography. The invention also concerns a method for identifying different adenovirus serotypes.

Abstract: The invention relates to a microfluidic device with microchannels that have separated regions which have a member of a specific binding pair member such as DNA or RNA bound to porous polymer, beads or structures fabricated into the microchannel. The microchannels of the invention are fabricated from plastic and are operatively associated with a fluid propelling component and detector.

Abstract: Compounds and methods are provided for use in purification of CD34+ cells and specific surface antigens thereof. The present invention discloses methods for releasing CD34+ cells, as well as compounds having a carbohydrate epitope of the CD34 surface antigen, from an affinity matrix, using carbohydrates having the structure: Neu5Ac&agr;2-3Gal&bgr;1-4(X) wherein (X) is GlcNAc, or a monosaccharide or a cyclohexane derivative that is structurally similar to GlcNAc.

Abstract: Methods for solid phase and combinatorial synthesis using a resin activation/capture approach are provided. In particular, methods for the production of dihydropyridones, N-acyidihydropyridones, tetrahydropyridones, pyridines, aminopyridines, N-acyltetrahydropyridines and tetrahydropyridines compounds and libraries containing such compounds are provided. Methods for screening the libraries and compounds and pharmaceutical compositions containing compounds prepared by the methods are provided.

Abstract: A method for detecting the binding of a test compound to a probe molecule comprises providing a test compound, the test compound having a first fluorophore bound thereto, and providing a screening substrate. The screening substrate comprises a solid support, a probe molecule bound to the solid support, and a second fluorophore bound to the solid support adjacent the probe molecule. An advantage of the invention is that this obviates the need for binding the second fluorophore directly to the probe molecule. Preferably, the second fluorophore is bound to the solid support by a flexible linker group. This enables the second fluorophore to interogate different positions on the probe molecule, which is also bound to the solid support adjacent the linker group, enhancing the ability of the method of the invention to detect positive binding events (specific binding of the test compound to the probe molecule.

Abstract: Substances such as chemical substances and biological substances including animal, vegetable and microbial cells are encapsulated using a process and an apparatus wherein a coil through which alternating current flows causes a magnet to vibrate creating vibrations such as in the range of between 300 to 4000 Hz that are transmitted to an encapsulating fluid containing the substance to form small substantially spherical particles containing the substance. The apparatus includes a pulsation chamber containing a movable wall for receiving the encapsulating fluid containing the substance to be encapsulated. A nozzle is spaced downstream from the pulsation chamber for receiving the encapsulating fluid from the pulsation chamber. A permanent magnet is mounted on the movable wall, and a coil is spaced from the permanent magnet by an air gap and is located proximate to the permanent magnet.

Abstract: A method is disclosed for producing a soluble conjugate vaccine, and preferably protein/polysaccharide conjugates. In this process, the polysaccharide is reacted with a reagent so as to provide a functional group on the polysaccharide molecule. Once the functional group is in place, the polysaccharide is reacted with a homobifunctional or heterobifunctional vinylsulfone to produce a vinylsulfone derivatized polysaccharide. Thereafter, the vinylsulfone derivatized polysaccharide is reacted with a protein to produce the conjugate. If desired, the protein may be derivatized with a functional group prior to the conjugation reaction step. In an alternative embodiment, the protein may be functionalized with a reactive group and then derivatized with the vinylsulfone group to produce a vinylsulfone derivatized protein. This protein may then be reacted with a polysaccharide to produce the conjugate. Optionally, the polysaccharide may be functionalized with a reactive group prior to the conjugation reaction.

Abstract: Microporous solid phase materials that are suitable for lateral flow and other assays for detecting the presence of analytes in test samples, that are stable under variations in humidity and, even after storage for extended periods of time, can form stable covalent bonds with molecules containing a free primary or secondary amine group or sulfhydryl group are described. The invention further concerns chemically derivatized solid phase materials, and conjugates comprising such materials. Examples of lateral flow devices for the quantitative or semi-quantitative determination of an analyte in a biological sample are described.

Abstract: The present invention concerns a method for separating at least one species of biological entities from a sample solution, by contacting the sample with a matrix of magnetic particles formed on a substrate such as a sheet a gel, etc. The particles in the matrix are coupled to entities capable of specifically binding to the species of biological entities to be separated. The separation is carried out either for detection purposes for obtaining separately each species of biological entities or for synthesis purposes. The invention further concerns matrices of magnetic particles formed on various substrates and kits for use in the method.

Abstract: A device that includes a living cell or tissue and an agent that inhibits the ability of a host molecule to damage the cell or tissue. The device can be constructed in various forms including an implantable device, a composite microreactor and a double composite microreactor. The composite microreactor includes an internal particle that includes a living cell or tissue, an internal particle matrix that includes the living cell or tissue and an internal semipermeable coating enclosing the internal particle matrix, a gel super matrix in which the internal particle is embedded, and an agent that inhibits the ability of a host molecule to damage the cell or tissue. The double composite microreactor includes an internal particle, a particle that includes a particle matrix in which the internal particle is embedded, a super matrix in which the particle is embedded, and an agent that inhibits the ability of a host molecule to damage the living cell or tissue.

Abstract: The present invention provides a method and a composition for detecting the levels of a plurality of biomolecular probes in a sample. In particular, the invention relates to a hybridization composition for detecting the presence or levels of different polynucleotide sequences in a sample.

Abstract: The present invention provides a viscometric method of detecting the presence or absence of an analyte in a solution. The method utilizes a dispersion of a conjugate and a receptor. The conjugate functions as an analog of the analyte, and the receptor can interact with both the analyte and the conjugate to change the viscosity of the dispersion. The test solution is introduced into an aliquot of the dispersion. Equivalent spots of the dispersion and the aliquot containing the analyte within the dispersion are then placed on a substrate such that the spots can spread upon the substrate. The presence of analyte in the test solution is detected by noting a change in the viscosity of the dispersion through a comparison of the spots. To facilitate the method, the invention provides a test kit comprising a conjugate comprising an analog of the analyte, a receptor binding the analog and the analyte, and a substrate upon which spots of liquid can spread.

Abstract: The present invention relates to processes for the direct detection of biochemically functional retroviruses in biological samples. The processes of the invention are characterized by the structure-specific extraction of retrovirus particles and a subsequent analysis and detection of retrovirus-specific enzymatic reactions. The processes of the invention have broad application in the diagnosis of retroviral infection and virological research.

Abstract: A hand held, self-contained, automatic, low power and rapid sensor platform for detecting and quantifying a plurality of analytes. A sample solution potentially containing an unknown amount of an analyte is passed through an affinity column which contains antibodies to which the analyte binds thereby extracting the analyte. The affinity column is then rinsed to remove any other chemicals that may fluoresce. The rinsed affinity column is then eluted with a known volume of elution fluid causing the analyte to release from the antibody and dissolve in the fluid (eluant). The eluant is then placed in the quartz cuvette of a fluorometer. The analyte suspended in the eluant fluoresces at a waveband which is different than that of the light source that excites it. The amount of fluorescence is measured and the level of analyte determined.

Abstract: Immobilization of SH group-containing compounds on a solvent-insoluble support is carried out in the presence of an antioxidant to prevent oxidation of SH groups to S—S bonds. This improves immobilization efficiency and suppresses deterioration of inherent characteristics of the SH group-containing compound. Antioxidants include sodium pyrosulfite (sodium disulfite), sodium sulfite, sodium hydrogensulfite, sodium hydrosulfite and L-ascorbic acid. SH group-containing compounds include cysteine, peptides or proteins containing cysteine and thiol compounds such as ethanethiol, aminoethanethiol, benzylthiol and thiophenol. Preferably, the SH group-containing compound has a molecular weight not more than 3×104. The support may be activated by a functional group such as glycidyl, imidocarbonato, tosyl, tresyl, carboxyl, amino, azido or hydroxyl. The support can be inorganic such as glass beads or organic such as a synthetic polymer or a polysaccharide.

Abstract: The invention describes the particles comprising an energy donor as a first component and a fluorescent dye as a second component positioned in said particles at an energy exchanging distance from one another, wherein the two components have a Stokes shift of greater than or equal to 50 nm, said particle having bound on its surface, a protein, polypeptide, nucleic acid, nucleotide or protein containing ligand analogue are disclosed and claimed. In addition, novel fluorescent dyes are described which exhibit intramolecular energy transfer for use to label various molecules, proteins, polypeptides, nucleotides and nucleic acids or to incorporate into particles.

Abstract: The invention relates to water-soluble polymeric thiosulfates, to a method for their preparation by polymer-analogous addition of tetrathionate to unsaturated polymers and to their application in surface coating.

Abstract: A method for isolating an active catalyst from a library of compounds that are potential catalysts is disclosed. The method involves providing a library which comprises a plurality of discrete solid supports, each solid support having a different organic compound bound thereto; and providing a reaction solution in a reaction vessel, the reaction solution containing the reactant or reactants necessary for a chemical reaction to occur in the presence of a catalyst for that reaction. The library and the reaction solution are then combined in the reaction vessel, and then one of the discrete solid supports is detected that is characterized by a temperature change in said solution greater than the temperature change of a plurality of other of said discrete solid supports in said solution. The detected solid support carries an active catalyst for the chemical reaction. Continuous flow apparatus for carrying out the method is also disclosed.

Abstract: Starting from two non-miscible phases, i.e., a lipophilic and a hydrophilic phase, a surface-active substance and a recognition component, a micellar recognition system is built in a suitable manner and is incorporated into a layer structure. The micellar recognition system is provided in a single thin layer in which the recognition component is distributed homogeneously. Additional layers which may be provided about this layer, have an influence on the properties of the entire layer structure. On contact between the layer structure and the substance to be measured a recognition step takes place in the layer which is followed by a transducing step. In this way a measurement variable is produced by means of which information is obtained on the substance. The layer structures exhibit higher sensitivity, a lower detection threshold, short response time and special robustness with regard to sample interference.

Abstract: The present invention provides a method for reducing undesirable light emission from a sample using at least one photon producing agent and at least one photon reducing agent (e.g. dye-based photon reducing agents). The present invention further provides a method for reducing undesirable light emission from a sample (e.g., a biochemical or cellular sample) with at least one photon producing agent and at least one collisional quencher. The present invention also provides a method for reducing undesirable light emission from a sample (e.g., a biochemical or cellular sample) with at least one photon producing agent and at least one quencher, such as an electronic quencher. The present invention also provides a system and method of screening test chemicals in fluorescent assays using photon reducing agents. The present invention also provides compositions, pharmaceutical compositions, and kits for practicing these methods.