Dextran-Conjugated Reagents for Rare Cell Detection
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Solution Overview
Problem
Current methods for detecting rare cells, such as circulating tumor cells (CTCs), in biological samples are limited and require additional reagents and methods for enhanced diagnostic and clinically relevant assays.
Innovation Solution
Development of detectable reagents comprising a binding moiety conjugated to multiple dextran components, each with a molecular weight of 30 kDa to 100 kDa, configured in a layered or branched configuration and attached to a detectable entity like a fluorophore, to enhance cell detection and quantification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detection reagents (single antibody or single fluorophore) are used, then the assay is simple to perform, but the detection sensitivity and signal-to-noise ratio are insufficient for rare cell detection
Solution Approach 1:
The patent employs composite reagent structures combining multiple functional components: antibodies (capture and detection), dextran carriers, and fluorophores. Specifically, biotinylated capture antibodies are immobilized on dextran beads, while fluorophore-conjugated detection antibodies bind to captured cells. This composite approach multiplies signal intensity through coordinated action of multiple reagents, achieving high detection sensitivity for rare cells while maintaining manageable procedural complexity through standardized protocols.
Solution Approach 2:
The detection system implements a nested structure where detection antibodies are bound to captured cells that are themselves immobilized on dextran beads. The fluorophore-conjugated detection antibodies form an outer layer around the captured target cells, creating a nested configuration: dextran bead → capture antibody → target cell → detection antibody → fluorophore. This nesting amplifies the signal by concentrating multiple fluorophores around each detected target, significantly improving signal-to-noise ratio for rare cell detection.
2Measurement precision
If multiple antibodies and reagents are used for CTC capture and detection, then detection specificity improves, but non-specific binding to non-target cells increases
Solution Approach 1:
The patent introduces dextran beads as an intermediary carrier between the capture antibody and the detection system. The biotinylated capture antibodies are immobilized on dextran beads, creating a physical and chemical intermediary layer that facilitates specific binding while reducing non-specific interactions. The dextran carrier provides a neutral, biocompatible surface that minimizes non-specific binding to non-target cells, allowing multiple antibodies to be used without proportionally increasing background noise.
Solution Approach 2:
The detection system applies local quality by using different antibodies with specific binding characteristics at different stages: capture antibodies with high affinity for target cell markers (e.g., EpCAM for CTCs) are used for selective immobilization, while detection antibodies with fluorophore conjugates provide localized signal amplification only at the site of captured targets. This spatial and functional differentiation ensures that non-specific binding occurs minimally while specific detection is maximized through localized signal generation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of these reagents significantly enhances cell detection sensitivity and specificity, reducing non-specific binding to non-target cells and providing a higher signal-to-noise ratio, allowing for more effective identification of rare cells like CTCs.
Implementation Method 1
a binding moiety conjugated to at least two dextran components... wherein the detectable reagent comprises about 4 to about 8 dextrans
Implementation Method 2
the detectable entity is a fluorophore, which can be selected from a fluorophore with green fluorescence, orange fluorescence, red fluorescence, and far red fluorescence
Data Source
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AI summary
The present invention provides reagents containing binding moieties conjugated to dextran moieties, methods of making such reagents, and use of such reagents in a variety of molecular and cellular assays.