Non-focusing Tracers for Indirect Detection in Isotachophoresis
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Solution Overview
Problem
Current indirect detection methods in electrokinetic processes, such as isotachophoresis, face limitations in accurately monitoring and analyzing analytes due to the focusing behavior of traditional background ions, which can interfere with the detection of physicochemical gradients and analyte properties.
Innovation Solution
The introduction of fluorescent non-focusing tracers (NFTs) that migrate through all zones of interest without focusing, allowing for the indirect detection of analytes by monitoring their concentration profiles and providing information on gradient regions, enabling the inference of analyte properties like mobility and pKa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional background ions are used as tracers in indirect detection methods, then the detection can be performed, but the focusing behavior of background ions interferes with the detection of physicochemical gradients and analyte properties
Solution Approach 1:
The patent changes the key parameter of tracer behavior from focusing to non-focusing by selecting ions with specific mobility characteristics that prevent them from forming discrete zones. This is achieved by using tracers whose mobility does not match the conditions required for isotachophoretic focusing, thereby eliminating the harmful focusing effect while maintaining detection capability
Solution Approach 2:
The non-focusing tracer acts as an intermediary substance that monitors the electrokinetic process without participating in the focusing mechanism. By being present in negligible concentration and not contributing significantly to current, the tracer indirectly reports on gradient regions and analyte properties without disrupting the system's natural behavior
2Illumination intensity
If fluorescent background ions are present in high concentration for indirect fluorescence detection, then detection signal is strong, but the tracer concentration significantly affects zones' electric fields and current distribution
Solution Approach 1:
Instead of using high concentrations of tracer, the patent employs partial action by using negligible tracer concentrations that are sufficient for detection purposes without significantly affecting the electric field or current distribution. This allows the system to maintain its natural electrokinetic behavior while still providing detectable signals
Solution Approach 2:
The patent changes the concentration parameter of the tracer from high (traditional approach) to negligible (novel approach). This parameter change eliminates the harmful effect of electric field distortion while maintaining adequate fluorescence signal for detection through sensitive instrumentation
3Stability of the object's composition
If non-focusing tracers are used in negligible concentration, then interference with electric fields is minimal, but the tracer signal must be detected with higher sensitivity
Solution Approach 1:
The patent substitutes the mechanical/electrical detection approach with optical detection using fluorescence. By employing fluorescently labeled non-focusing tracers, the system leverages optical detection methods which offer higher sensitivity and can detect much lower concentrations than traditional electrical or UV absorption methods
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 precise monitoring and analysis of analytes in both peak and plateau modes, providing accurate information on mobility, pKa, and interaction properties, even in complex electrokinetic processes, with minimal interference from the tracers' presence.
Implementation Method 1
Isotachophoresis (ITP) is an established technique for analyte preconcentration and separation in which ions form discrete and contiguous zones between a fast leading electrolyte (LE) and a slow trailing electrolyte (TE)
Implementation Method 2
We add a fluorescent non-focusing tracer (NFT) to the LE or TE in concentrations which do not significantly affect zones' electric fields
Data Source
AI summary
A novel method for visualizing electrokinetic process zones (e.g., for isotachophoresis (ITP)) is provided. We introduce negligibly small concentrations of a fluorophore that is not focused by isotachophoresis. This non-focusing tracer (NFT) migrates through multiple isotachophoresis zones. As it enters each zone, the NFT concentration adapts to the local electric field in each zone. ITP zones can then be visualized with a point detector or camera. The method can be used to detect, identify, and quantify unknown analyte zones, and can visualize complex and even transient electrophoresis processes. This visualization technique is particularly suited to microfluidic and lab-on-a-chip applications, as typical fluorescence microscopes and CCD cameras can provide high-resolution spatiotemporal data.