Dynamic Binding Event Tracking for Interferometric Biosensing
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Solution Overview
Problem
Current single molecule detection technologies are limited by the affinity of capture probes, leading to variations in sensitivity and specificity, and lack a kinetic assay capable of measuring transient interactions on a large sensor surface with low magnification while distinguishing specific from nonspecific binding events.
Innovation Solution
A method and apparatus using a sensing surface with a camera and computer to track nanoparticle interactions over time, analyzing images to distinguish specific binding events by measuring dwell times and eliminating false positives/negatives, without chemical amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single molecule detection technologies are used, then sensitivity is improved, but assay time increases and measurement precision varies due to probe affinity limitations
Solution Approach 1:
The system transitions from static endpoint measurements to dynamic kinetic monitoring, continuously tracking binding events in real-time. This allows the assay to capture transient interactions and determine both association and dissociation rates, improving measurement precision without requiring extended incubation times.
Solution Approach 2:
The invention replaces chemical amplification methods with direct optical detection of single binding events. By using total internal reflection fluorescence (TIRF) microscopy and photon counting, the system achieves single molecule sensitivity without the time-consuming amplification steps required by traditional methods.
2Measurement precision
If capture probes with high affinity are used, then sensitivity is improved, but specificity decreases due to nonspecific binding
Solution Approach 1:
The system uses real-time kinetic monitoring to distinguish specific from nonspecific binding events. By analyzing the temporal characteristics of binding (association and dissociation rates), the system provides feedback that allows differentiation between high-affinity specific interactions and lower-affinity nonspecific binding, even when both occur simultaneously.
Solution Approach 2:
The invention changes the measurement parameter from static endpoint binding quantity to dynamic kinetic rates. By measuring association rate constants (k_on) and dissociation rate constants (k_off), the system can identify specific binding events through their characteristic kinetic signatures, separating them from nonspecific binding regardless of probe affinity.
3Device complexity
If endpoint assays are used, then device complexity is reduced, but measurement precision decreases for transient interactions
Solution Approach 1:
The system implements continuous monitoring of binding events throughout the assay period, rather than taking a single endpoint measurement. This continuous observation captures transient interactions that would be missed in endpoint assays, improving measurement precision while maintaining relatively simple instrumentation based on established TIRF microscopy techniques.
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
Enhances sensitivity and reduces assay time by accurately detecting transient interactions of target molecules with a sensor surface, distinguishing specific from nonspecific binding, even at low concentrations.
Implementation Method 1
a camera for generating an image of the surface
Data Source
AI summary
Herein is described kinetic assay, in which individual binding events are detected and monitored during sample incubation. This method uses interferometric reflectance imaging to detect thousands of individual binding events across a multiplex solid phase sensor with a large area. A dynamic tracking procedure is used to measure the duration of each event. From this, the total rates of binding and de-binding as well as the distribution of binding event durations are determined. Systems and components for performing the kinetic assay are also described.