Highly sensitive visual detection of nucleic acid based on a universal strand exchange amplification coupled with lateral flow assay strip

Amplification reactions coupled with electrophoresis or real-time fluorescence system have been successfully used for the analysis of nucleic acid. However, complex procedures or expensive instruments greatly limit their application in low-resource settings. To address these shortcomings, we fabricated a universal and simple detection platform by integrating strand exchange amplification (SEA) with lateral flow assay (LFA) strip. SEA is a simple isothermal amplification reaction, only requires a pair of primers and one DNA polymerase, above all, its short amplicons are easy to migrate on the strip. LFA strip was proved to be stable for months without large signal deviations and result could be easy to read by naked eyes, which makes it an appropriate option for field-based analysis. Our proposed SEA-LFA strip could reliably detect as few as 0.05 nM pork DNA and 0.07 nM duck DNA by the naked eye, its analytical performance is comparable with laboratory-based real-time fluorescence test. Furthermore, this proof-of-concept method could be applied to detect a wide variety of nucleic acid by focusing on primer design rather than on the development of a wholly new analysis platform. We believe that this simple visualization system has great potential as a preliminary test tool in resource-limited areas.