Assay Device Surface Modification for Analyte Binding Optimization
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Solution Overview
Problem
Current immunodiagnostic assays face challenges in accurately measuring analyte concentrations due to errors from faulty assay techniques, variability in sample concentration, temperature, and interference from cross-reactivity and matrix effects, leading to inaccurate sensitivity and precision measurements.
Innovation Solution
The method involves modifying the surface of an assay device to optimize the attachment of site-specific immobilized arrays with a balance of hydrophilic, hydrophobic, and covalent linking sites, allowing for modulated and quantifiable attachment of analyte and antibody, enabling internal dynamic calibration and reducing external reference errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external calibration standards are used, then calibration curves can be created, but measurement accuracy deteriorates due to matrix effects and variability from external references
Solution Approach 1:
The patent introduces an internal calibration standard that acts as an intermediary reference within the assay matrix itself. This internal standard co-elutes with the analyte and experiences the same matrix effects, providing a reliable reference that compensates for variability. The internal calibration standard serves as a mediator between the analyte measurement and the detector, correcting for matrix-induced signal variations without requiring external references that may not reflect actual sample conditions.
2Measurement precision
If repeated measurements are performed to reduce standard error, then measurement precision improves, but assay time and productivity deteriorate
Solution Approach 1:
The patent performs preliminary action by incorporating the internal calibration standard into the assay protocol from the beginning, allowing simultaneous measurement of both analyte and calibration reference in the same run. This eliminates the need for separate repeated measurements of calibration standards, as the internal standard provides continuous reference data throughout the assay, thereby maintaining precision without sacrificing throughput.
3Reliability
If surface charge on substrate is increased to enhance binding, then antibody-antigen binding improves, but non-specific adsorption and cross-reactivity increase
Solution Approach 1:
The patent applies local quality by creating distinct functional zones on the substrate surface with different charge characteristics. The capture antibody region is optimized with appropriate surface charge for specific binding, while separate regions are designated for internal calibration standards and blocking agents. This spatial differentiation of surface properties allows each zone to perform its specific function optimally without interfering with other zones, reducing non-specific adsorption while maintaining reliable binding where needed.
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 enhances the sensitivity and accuracy of analyte detection, providing a reliable and reproducible method for measuring analyte concentrations across a dynamic range of femtomol to nanomol per ml, addressing the limitations of external calibration and improving diagnostic reliability.
Implementation Method 1
modifying said surface to provide hydrophobic binding sites, hydrophilic linking sites and covalent linking sites
Implementation Method 2
modifying said surface to provide hydrophobic binding sites, hydrophilic linking sites and covalent linking sites
Implementation Method 3
modifying said surface to provide hydrophobic binding sites, hydrophilic linking sites and covalent linking sites
Implementation Method 4
a test dot including a capture antibody for binding said analyte
Data Source
AI summary
The present invention provides a method of making an assay device for conducting an assay to detect a concentration of an analyte in a sample fluid. The assay devices would typically have a substantially planar surface having a series of site specific immobilized calibration spot arrays containing pre-determined quantities of the analyte printed thereon. In addition, a series of site specific immobilized test spot arrays, including capture antibody for binding the analyte protein is printed on the assay device. The method involves first modifying the planar surface to provide hydrophobic binding sites, hydrophilic linking and covalent bonding sites. Then the method requires printing the series of site specific immobilized test spot arrays and the series of site specific immobilized calibration spot arrays on the substantially planar surface. Applying the sample fluid to the assay device is the next step followed by testing a sensitivity of the assay and modulating ratios of the hydrophobic, hydrophilic and covalent binding sites in order to optimize the sensitivity of the assay.