Coupling Sensitive Nucleic Acid Amplification with Commercial Pregnancy Test Strips

The detection of nucleic acid biomarkers for point-of-care (POC) diagnostics is currently limited by technical complexity, cost, and time constraints. To overcome these shortcomings, we have combined loop-mediated isothermal amplification (LAMP), programmable toehold-mediated strand-exchange signal transduction, and standard pregnancy test strips. The incorporation of an engineered hCG-SNAP fusion reporter protein (human chorionic gonadotropin-O-6-alkylguanine-DNA alkyltransferase) led to LAMP-to-hCG signal transduction on low-cost, commercially available pregnancy test strips. Our assay reliably detected as few as 20 copies of Ebola virus templates in both human serum and saliva and could be adapted to distinguish a common melanoma-associated SNP allele (BRAF V600E) from the wild-type sequence. The methods described are completely generalizable to many nucleic acid biomarkers, and could be adapted to provide POC diagnostics for a range of pathogens.