| 摘要 |
An assay, method of performing said assay, and apparatus, capable of generating an "on"/"off" response from a changing concentration of ample analyte, are described. The assay system comprises a high affinity binding component for a sample analyte and has an analyte dissociation constant substantially less than the concentration of analyte to be measured. Under initial conditions, wherein there is an absence of added analyte, a substantial number of binding sites must be empty. The concentration of empty binding sites determines the threshold analyte concentration, or "trigger point," for the "on"/"off" switch. Also required are a means for determining when excess analyte is present after the binding sites are substantially completely filled, wherein said means has an affinity for analyte which is substantially less than the binding component affinity for analyte. Also described is a diagnostic apparatus, comprising a set of compartments, each with a different threshold analyte concentration. A signal is generated in each compartment only when the analyte concentration is greater than the preset threshold, allowing instrument-independent, accurate measurement of analyte concentration.
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