Lyophilised colourimetric LAMP for visual readout with dual colour indicators

Area of Science:

• Molecular Diagnostics
• Isothermal Amplification Technologies

Background:

• Loop-mediated isothermal amplification (LAMP) is a viable alternative to PCR for pathogen detection.
• Colourimetric LAMP (cLAMP) enables instrument-free readout, ideal for low-resource settings.
• Current cLAMP formats require cold-chain storage and trained personnel, limiting point-of-care use.

Purpose of the Study:

• To develop and optimize ready-to-use lyophilised colourimetric LAMP (lyo-cLAMP).
• To create a stable, cold-chain-independent cLAMP assay for point-of-care diagnostics.
• To demonstrate the adaptability and accuracy of lyo-cLAMP for pathogen detection.

Main Methods:

• Screening and combining pH and metal indicators for optimal colourimetric discrimination.
• Optimizing lyophilisation protocols for ready-to-use cLAMP formulations.
• Assessing lyo-cLAMP performance using synthetic SARS-CoV-2 RNA and clinical samples.

Main Results:

• Identified four pH and metal indicator combinations with high discrimination.
• Achieved equivalent limit-of-detection for lyo-cLAMP compared to liquid cLAMP with SARS-CoV-2 RNA.
• Demonstrated high accuracy in screening clinical samples for SARS-CoV-2.

Conclusions:

• Developed lyophilised colourimetric LAMP (lyo-cLAMP) as a stable, reagent-free, cold-chain-independent diagnostic tool.
• lyo-cLAMP simplifies molecular diagnostics for point-of-care applications.
• The assay is adaptable to various targets, crucial for rapid response during outbreaks.