LSPR Enzymatic Assay for Low Concentration Detection
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Solution Overview
Problem
Conventional colorimetric enzyme immunoassays have limitations in sensitivity and dynamic range due to direct detection methods, which restrict accurate measurement to optical densities below 2 and a narrow detection range of about one order of magnitude, and are not applicable to a wide range of enzyme/substrate combinations.
Innovation Solution
The method employs a localized surface plasmon resonance (LSPR) detection system with gold-coated nanoparticles, where an immobilized enzyme converts a substrate to an insoluble product that accumulates on the LSPR surface, causing a shift in reflected or transmitted light, allowing indirect detection at lower concentrations and expanding the dynamic range by monitoring refractive index changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If direct colorimetric detection is used, then the assay is simple and convenient, but the dynamic range is limited to about one order of magnitude and accurate measurement is only possible for optical densities below 2
Solution Approach 1:
The patent introduces LSPR (localized surface plasmon resonance) as an intermediary detection mechanism between the enzymatic reaction and the measurement system. The LSPR surface acts as a mediator that converts the insoluble product accumulation into refractive index changes, which can be detected over a wider dynamic range without compromising assay simplicity
Solution Approach 2:
The patent changes the detection parameter from direct optical density measurement to refractive index measurement via LSPR. This parameter change enables extension of the dynamic range beyond the traditional colorimetric limits while maintaining the simplicity of the assay format
2Measurement precision
If the amount of enzyme is increased to improve sensitivity, then detection sensitivity improves, but the limit on how much antibody can be attached to a solid surface is reached
Solution Approach 1:
The patent replaces the mechanical/conventional optical detection system with an LSPR-based detection system that is more sensitive to changes in the local refractive index. This substitution allows detection at lower enzyme amounts by detecting the refractive index changes caused by insoluble product accumulation on the LSPR surface
Solution Approach 2:
The patent changes the detection parameter from absorbance to refractive index, which is highly sensitive to the presence of insoluble products. This parameter change enables detection with much lower enzyme amounts, overcoming the limitation of antibody attachment capacity on solid surfaces
3Productivity
If temperature is raised to accelerate enzymatic reaction, then reaction speed improves, but enzyme degradation occurs
Solution Approach 1:
The patent substitutes the temperature-based reaction acceleration approach with an LSPR-based detection approach. The LSPR system detects the accumulation of insoluble products with high sensitivity, allowing the use of lower temperatures that preserve enzyme stability while still achieving adequate reaction speeds for detection
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 sensitivity, shortens assay time, and extends the dynamic range of colorimetric enzyme immunoassays by leveraging the sensitive refractive index changes induced by the insoluble product on the LSPR surface, enabling detection at lower antigen concentrations and improving the overall detection capability.
Implementation Method 1
The method includes detecting changes in the reflected or transmitted light of the surface arising from the presence of the insoluble product using LSPR
Implementation Method 2
generating an insoluble product from an enzymatic substrate using an immobilized enzyme
Data Source
AI summary
The present invention provides a method of detecting changes in the refractive index at the surface of a localized surface plasmon resonance (LSPR) detection system. The method includes generating an insoluble product from an enzymatic substrate using an immobilized enzyme, wherein the insoluble product accumulates at a LSPR supporting surface. The method also includes detecting changes in the reflected or transmitted light of the surface arising from the presence of the insoluble product using LSPR.