Immunochromatographic protocols in which analytes, such as a bacteria or virus, are assayed using a "sandwich" complex; binding of antibody to antigen takes place in solution phase for improved sensitivity, and are then bound in the capture zone; maintains benefits fo conventional strips
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Publication Number
US-7919331-B2
Publication Date
2011-04-05
Expiration Date
Abstract
The invention describes immunochromatographic protocols in which one or more analytes, such as a bacteria or virus, can be assayed utilizing a “sandwich” complex.
Core Innovation
The invention relates to immunochromatographic sandwich assays for detecting an analyte in a sample solution. Binding is initiated in solution by combining a first labeled analyte-binding molecule and a second labeled analyte-binding molecule, where the combination forms a complex when contacted by fluid comprising the analyte.
The resulting analyte complex is then directed into a chromatographic test strip in which capture is mediated at a capture zone using a binding molecule suitable to bind to the second label. A first-label-binding molecule comprising a signal reagent is used to bind the complex, and detection is based on whether the signal reagent is present in the capture zone of the chromatographic test strip.
The disclosure provides device and method embodiments that support modular inclusion of multiple analyte specificities and visual lines or spectrophotometric/UV detection. It also includes alternative configurations such as double-label or single-label formats, placement of reagents on-strip versus in-sample, and multi-epitope capture approaches.
Claims Coverage
The independent claims cover a device and a method that use two labeled analyte-binding molecules to form a complex in solution, a first-label-binding molecule carrying a signal reagent, and a chromatographic test strip with a capture zone that binds the second label. The coverage centers on fluid communication between the complex, the signal-reagent binding molecule, and a capture zone binding molecule, with analyte presence determined by signal at the capture zone.
Solution complex formation with first and second labels
components comprising an analyte-binding molecule having a first label and a second analyte-binding molecule having a second label, wherein the combination of the components is capable of forming a complex when contacted by fluid comprising the analyte;
Signal reagent binding to the labeled analyte complex
a first-label binding molecule comprising a signal reagent, capable of binding the complex of (a);
Capture zone binding to the second label in fluid communication
a solid support comprising a capture zone, the capture zone comprising a binding molecule suitable to bind to the second label, wherein the complex of (a) is in fluid communication with the binding molecule of (b) and with the capture zone.
Method steps: contact to form complex, signal reagent binding, chromatographic flow to capture zone
contacting a solution suspected of comprising the analyte with a first analyte-binding molecule having a first label and a second analyte-binding molecule having a second label, wherein the combination of the binding molecules is capable of forming a complex when contacted by fluid comprising an analyte; contacting the solution containing the complex with a first-label-binding molecule comprising a signal reagent; flowing the solution comprising the complex and the first-label-binding molecule comprising a signal reagent through a chromatographic test strip to a capture zone, comprising a binding molecule suitable to bind to the second label;
Determining analyte presence by signal reagent in the capture zone
determining the presence of the analyte in the solution by the presence of the signal reagent in the capture zone of the chromatographic test strip.
Overall, the claim set is directed to a sandwich-like immunochromatographic system in which a labeled binding-pair forms a complex in solution, the complex is bound by a signal-reagent-containing binding molecule associated with the first label, and the complex is captured in a capture zone via binding to the second label. Analyte presence is determined by the presence of the signal reagent at the capture zone.
Stated Advantages
improved sensitivity for low/complex samples
preserves strip usability while enabling modular, cost-effective incorporation of many analyte specificities in one test with a single readout
Documented Applications
detection of microorganisms including Escherichia coli and other bacterial targets
multi-analyte detection using label pairs and corresponding label-binding molecules (e.g., biotin/streptomycin with corresponding binding chemistry)
detection by visual lines and by spectrophotometric/UV detection
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