Capillary Laminar Flow Kd Determination via Transverse Diffusion
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Solution Overview
Problem
Current methods for determining the equilibrium dissociation constant (Kd) of reversible binding pairs, such as fluorescence spectroscopy, thermophoresis, sensor-based techniques, and isothermal titration calorimetry, face challenges including labeling issues, immobilization problems, and systematic errors, leading to inaccurate and time-consuming measurements.
Innovation Solution
A method involving the injection of a sample containing a reversible binding pair into a capillary tube under laminar flow conditions, where the separation of bound and unbound compounds occurs through transverse diffusion, allowing for the measurement of a signal proportional to the concentration of the compounds over time, and subsequent determination of Kd using non-linear regression analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluorescence spectroscopy or thermophoresis is used to determine Kd, then measurement can be performed, but labeling with fluorophore affects binding accuracy
Solution Approach 1:
The invention extracts and eliminates the fluorophore labeling step from the measurement process. By using label-free techniques such as surface-plasmon-resonance and biolayer interferometry, the method removes the harmful fluorophore attachment while maintaining the ability to measure Kd accurately through optical detection of binding events without molecular labels.
Solution Approach 2:
The invention introduces an intermediary sensing mechanism (surface-plasmon-resonance or biolayer interferometry) that mediates the detection of binding events. Instead of labeling the molecules themselves, these intermediary optical techniques detect changes in refractive index or interference patterns caused by binding, allowing accurate measurement without direct fluorophore attachment to the binding partners.
2Measurement precision
If sensor-based techniques are used to determine Kd, then measurement can be performed, but immobilization on sensor surface affects binding activity and accessibility
Solution Approach 1:
The invention extracts and eliminates the immobilization step from the measurement process. By using solution-phase binding assays detected through advanced optical methods, the approach removes the harmful surface attachment while maintaining accurate Kd measurement capability through detection of binding events in free solution.
Solution Approach 2:
The invention introduces an intermediary detection system that measures binding events without requiring immobilization. The optical sensing mechanisms detect refractive index changes or interference patterns in solution, serving as an intermediary that bridges the need for measurement with the requirement to maintain natural binding behavior in solution phase.
3Measurement precision
If sensor-based techniques or ITC are used to determine Kd, then measurement can be performed, but inside-the-instrument equilibration makes measurements slow
Solution Approach 1:
The invention performs preliminary equilibration of binding reactions outside the instrument before measurement. By allowing binding to reach equilibrium in solution prior to introduction into the detection system, the method eliminates the time-consuming inside-the-instrument equilibration step while maintaining accurate Kd determination through pre-equilibrated samples.
Solution Approach 2:
The invention skips the slow inside-the-instrument equilibration step by using pre-equilibrated samples. The rapid optical detection methods allow the system to rush through the measurement process quickly once samples are prepared, achieving both speed and accuracy by eliminating the bottleneck equilibration step from the instrument operation.
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
This approach provides an accurate, label-free, and immobilization-free method for determining Kd, minimizing errors and increasing measurement speed, suitable for high-throughput screening of therapeutic agents and polypeptide-molecule interactions.
Implementation Method 1
the separation of bound and unbound compounds occurs through transverse diffusion
Implementation Method 2
injection of a sample containing a reversible binding pair into a capillary tube under laminar flow conditions
Data Source
AI summary
A method and system for determining the dissociation constant (Kd) of a reversible binding pair of a first compound and a second compound. The method comprises: injecting a sample into a capillary tube via one or more valves, wherein the sample comprises the first compound, the second compound, and a first compound-second compound complex; injecting a mobile phase into the capillary tube via said one or more valves, the sample flowing through the capillary tube under laminar flow conditions, wherein the second compound and the first compound-second compound complex is separated from the first compound by transverse diffusion; measuring time dependence of a signal that is proportional to the concentration of the first compound, both unbound and bound to the second compound using a measurement component; and determining the equilibrium dissociation constant based on the measured signal versus time dependence.