SPR Auto-Blank for Non-Specific Binding in Complex Samples
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Solution Overview
Problem
Current methods for determining active concentrations and kinetic interaction constants of analytes in complex biological samples, such as human serum or plasma, face challenges due to non-specific binding issues, which hinder accurate analysis using surface plasmon resonance (SPR) techniques.
Innovation Solution
A modified SPR method involving a surface plasmon resonance chip with a capture agent specific for the analyte's ligand, where a control ligand and the target ligand are of similar mass and captured in equivalent quantities, allowing for the subtraction of non-specific binding effects to calculate active concentrations and kinetic constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SPR technique is used to determine active concentrations and kinetic constants in complex biological samples, then measurement precision is improved, but non-specific binding occurs leading to inaccurate results
Solution Approach 1:
The patent introduces a control ligand as an intermediary element that mimics the target ligand's properties (mass, capture efficiency) but does not bind the analyte. This control ligand serves as a mediator to measure and quantify non-specific binding effects, which are then subtracted from the target ligand measurements to obtain accurate results.
Solution Approach 2:
The control ligand is designed as a copy of the target ligand in terms of physical properties (mass, structure) and interaction characteristics (capture by capture agent), but lacks the specific binding capability to the analyte. This copying approach allows the system to replicate non-specific binding conditions without the confounding factor of specific analyte-ligand interaction.
2Measurement precision
If control ligand and target ligand are used to correct non-specific binding, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The control ligand serves multiple functions: it acts as a reference for non-specific binding measurement, maintains similar physical properties to the target ligand for comparable behavior, and enables mathematical correction of the target ligand data. This multi-functionality is achieved within the existing SPR chip architecture without requiring separate instruments or complex additional components.
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 enables reliable determination of active concentrations and kinetic constants in complex biological samples by correcting for non-specific binding, providing accurate and reproducible results for analytes like anti-HLA antibodies, thereby improving the analysis of complex media.
Implementation Method 1
SPR relies on the changes in reflective properties of a thin gold layer. Under conditions of total internal reflection, the polarized light generates an evanescent wave that penetrates the thin gold layer and extends a few hundred nanometers into the buffer, where some of the photons are absorbed. The angle at which this minimum occurs is called the resonance angle and varies depending on the mass present in the evanescent wave field, near the gold layer; any change in mass modifies the refractive index.
Implementation Method 2
Under conditions of total internal reflection, the polarized light generates an evanescent wave that penetrates the thin gold layer
Implementation Method 3
a specific capture agent for a ligand of the analyte is immobilized; the capture by the capture agent of a control ligand not binding the analyte to be tested
Data Source
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AI summary
The invention relates to a method for determining active concentrations of an analyte and optionally kinetic constants for the interaction of the analyte with a ligand in complex biological samples by means of surface plasmon resonance comprising the use of an auto-blank.