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Avidin-Functionalized Gold Nanoparticles Enable Cationic Isotachophoresis for Enhanced Lateral Flow Assays
Devon McCornack1, Cornelius F Ivory1, Zhihong Zhang2,3
1Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington99163, United States.
Analytical Chemistry
|July 14, 2026
Summary
A new LIGMA assay uses isotachophoresis to improve sensitivity in rapid diagnostics. This electrokinetic strategy enhances biomolecular separation for better point-of-care testing.
Area of Science:
- Biomedical Engineering
- Analytical Chemistry
- Biosensing Technology
Background:
- Lateral flow assays (LFAs) are crucial for point-of-care diagnostics but face sensitivity limitations due to passive migration and protein interference.
- Existing methods for enhancing LFAs often struggle with sample matrix effects and analyte focusing.
- Novel strategies are needed to improve the performance of paper-based diagnostic platforms.
Purpose of the Study:
- To introduce a novel diagnostic platform, the lateral isotachophoresis-guided migration analysis (LIGMA) assay.
- To leverage cationic isotachophoresis (+ITP) for enhanced biomolecular separation and detection in LFAs.
- To overcome limitations of conventional methods by enabling direct electrophoretic migration of analytes.
Main Methods:
- Development of avidin-functionalized gold nanoparticles (AV-S-GNPs) as positively charged nanocarriers.
- Application of cationic isotachophoresis (+ITP) to guide electrophoretic migration of negatively charged analytes within LFAs.
- Characterization of nanoparticle stability and electrophoretic mobility under +ITP conditions.
Main Results:
- The LIGMA assay demonstrated a limit of detection of 1.97 nM and a limit of quantification of 4.12 nM for human IgG.
- Achieved high sensitivity with only 1 μL of sample volume and assay times under 2 minutes.
- Observed sharper capture line resolution, improved analyte focusing, and reduced background interference compared to standard LFAs.
Conclusions:
- The LIGMA assay represents a viable electrokinetic strategy for significantly improving paper-based biosensors.
- This approach enhances sensitivity and reduces interference, paving the way for more accurate point-of-care diagnostics.
- The LIGMA platform offers potential for expanded applications in clinical diagnostics and portable biosensing.
