Recombinase-aided amplification combined with lateral flow dipstick for the rapid detection of Amphidinium carterae

In the context of global climate change, the frequency and duration of harmful algal blooms (HABs) due to eutrophic coastal waters have increased. HABs can cause marine ecological imbalance, massive socio-economic damage, and potential public health problems. Therefore, accurate and specific techniques that can rapidly detect harmful algae are critical to expedite early monitoring and prediction of HABs. Although some methods based on amplification have previously been described, limitations associated with limited popularity and high costs still exist. In this study, the partial sequence of nuclear ribosomal DNA from Amphinidium carterae was selected as the target region. The biotin-labeled recombinase-aided amplification (RAA) products and the 6-carboxyfluorescein-labeled probe were specifically conjugated, which formed double-labeled RAA products analyzed by lateral flow dipstick (LFD). A rapid RAA–LFD assay aimed at visually detecting A. carterae was established and optimized. The specificity and sensitivity of RAA–LFD were determined. The nucleic acid test with other control algal species yielded negative results, which indicated that RAA–LFD assay can specifically detect A. carterae. The detection limit of RAA–LFD assay for A. carterae was 8.49 ng μL⁻¹ genomic DNA and 1 cell mL⁻¹. The whole detection process of RAA–LFD could be completed within 50 min. In conclusion, the proposed RAA–LFD assay may be promising for the efficient, specific, and rapid detection of A. carterae in monitoring efforts.