Abstract: This invention presents novel assay devices employing capture reagents, involving a specific binding member attached to a charged substance, and porous material containing a capture or reaction zone that is oppositely charged with respect to the charged substance included in the capture reagent. In one embodiment, a test sample suspected of containing the analyte of interest is contacted with the capture reagent to form a charged capture reagent/analyte complex. The complex is then contacted to the oppositely charged capture or reaction zone to attract, attach, and immobilize the capture reagent/analyte complex. With an appropriate indicator reagent, both sandwich and competitive assays can be performed.

Abstract: A method, composition, device, apparatus, and kit for the determination of the presence or amount of an analyte by monitoring an analyte-mediated ligand binding event in a test mixture which contains the analyte to be assayed, a specific binding member, a Raman-active label, and a particulate having a surface capable of inducing a surface-enhanced Raman light scattering. The test mixture is illuminated with a radiation sufficient to cause the Raman-active label in the test mixture to emit a detectable Raman spectrum. The differences in the detected surface-enhanced Raman scattering spectra are dependent upon the amount of the analyte present in the test mixture. Thus, by monitoring these differences, the presence or amount of the analyte are determined.

Abstract: The present invention includes novel digoxin assays employing a capture reagent, involving a first binding member conjugated to a polymeric anion substance, and a solid phase material containing a reaction site comprising a polymeric cation substance having a nitrogen content of at least about two percent. A test sample suspected of containing the analyte of interest may be contacted with the capture reagent to form a charged capture reagent/analyte complex. The complex is then contacted to the oppositely charged solid phase to attract, attach, and immobilize the capture reagent/analyte complex.

Abstract: A method, composition, device, apparatus, and kit for the determination of the presence or amount of an analyte by monitoring an analyte-mediated ligand binding event in a test mixture which contains the analyte to be assayed, a specific binding member, a Raman-active label, and a particulate having a surface capable of inducing a surface-enhanced Raman light scattering. The test mixture is illuminated with a radiation sufficient to cause the Raman-active label in the test mixture to emit a detectable Raman spectrum. The differences in the detected surface-enhanced Raman scattering spectra are dependent upon the amount of the analyte present in the test mixture. Thus, by monitoring these differences, the presence or amount of the analyte are determined.

Abstract: A 4-methylumbelliferyl phosphate substrate for use in conducting an immunoassay is disclosed. The substrate contains 0.1 gram mole per liter 2-amino-2-methyl-1-propanol, 0.01 to 0.05 gram mole per liter EDTA, added as trisodium EDTA, 1 gram per liter sodium azide, 1.2 milligram mole per liter 4-methylumbelliferyl phosphate and 4 milligram moles per liter tetramisole. The pH of the substrate disclosed is 10.3.