Immunochromatographic Strip Layout for Longer Nitrous Acid Extraction
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Solution Overview
Problem
Existing immunochromatography methods for detecting Streptococcus species suffer from insufficient sensitivity due to inadequate nitrous acid extraction time, leading to non-specific reactions and incomplete antigen detection.
Innovation Solution
An immunochromatographic device with a sloped support structure and regions impregnated with nitrite or acid reagents, along with a neutralizing reagent, controls the development time of the sample on the test strip, ensuring sufficient nitrous acid extraction and neutralization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sample flows fast through the test strip as in conventional immunochromatography, then the procedure is simple and rapid, but nitrous acid extraction is insufficient and detection sensitivity becomes insufficient
Solution Approach 1:
The invention dynamically controls the sample flow rate through the test strip by adjusting the capillary action properties of the support material. The sample flows at different speeds at different regions: slower in the nitrous acid generation region to allow sufficient extraction time, and faster in other regions to maintain overall procedure efficiency. This dynamic flow control resolves the contradiction between rapid procedure and sufficient extraction.
Solution Approach 2:
The support material is designed with locally differentiated properties: the nitrous acid generation region has specific capillary action characteristics that slow down sample flow, while other regions have different properties optimized for their functions. This local quality variation allows the sample to spend sufficient time (1-2 minutes) in the extraction region while maintaining overall procedural efficiency.
2Measurement precision
If a pad made of hydrophobic material is used to perform sufficient extraction, then nitrous acid extraction is sufficient, but the sample development becomes excessively slow and the sample cannot develop throughout the test strip within the reaction period
Solution Approach 1:
The support material provides dynamic flow control where the sample moves at optimized speeds through different regions. The hydrophobic properties are balanced with capillary action to ensure the sample develops sufficiently through the entire test strip within the reaction period while spending adequate time in the extraction region for sufficient antigen extraction.
Solution Approach 2:
The physical and chemical parameters of the support material are optimized to balance extraction efficiency and development speed. By adjusting parameters such as porosity, hydrophobicity, and capillary action, the system achieves both sufficient extraction and complete sample development within the available reaction time.
3Ease of operation
If the immunochromatographic test strip is impregnated with nitrous acid solution or acid solution in dried form, then the procedure becomes simple without mixing reagents, but sample extraction time is insufficient and detection sensitivity becomes insufficient
Solution Approach 1:
The nitrite and acid reagents are pre-loaded onto the support material in dried form during manufacturing. When the sample is applied, these reagents automatically dissolve and react to generate nitrous acid in situ, eliminating the need for manual reagent mixing while providing sufficient extraction time as the sample flows through the prepared regions.
Solution Approach 2:
The test strip performs self-service by automatically generating nitrous acid from the pre-loaded nitrite and acid reagents when the sample is applied. The system self-regulates the extraction process without requiring external intervention for reagent preparation or mixing, maintaining procedural simplicity while ensuring adequate extraction time.
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
The device enables prolonged nitrous acid extraction and neutralization, enhancing detection sensitivity and preventing non-specific reactions, thereby improving the accuracy of sugar chain antigen detection.
Implementation Method 1
extraction of antigens with nitrous acid is performed by mixing a nitrite solution with an acid solution (e.g., acetic acid, citric acid, or tartaric acid) at the time of use to generate nitrous acid
Implementation Method 2
controls the chromatography developmental speed on the immunochromatographic test strip
Data Source
AI summary
This invention provides a method and an immunochromatographic device that enable measurement with sufficient sensitivity by performing nitrous acid extraction over a sufficiently long period of time in an immunochromatographic method comprising extracting a sugar chain antigen with nitrous acid and measuring the extracted sugar chain antigen on an immunochromatographic test strip. Such immunochromatographic device comprises a specimen dropping port on top of a sample pad of the test strip. The immunochromatographic device has: (i) a wide specimen dropping port to promote sugar chain antigen extraction with a nitrite and a solid acid reagent by retaining the added specimen sample solution and supplying the specimen sample solution to the region impregnated with the solid acid reagent or the nitrite within a short period of time; and (ii) no gaps between the dropping port and the sample pad so as to prevent the sample from leaking from the dropping port.