A Chromatography Test Strip of Exonuclease III-Amplified Aptamer for Rapid Identification of Prorocentrum minimum

Recently, the scale and frequency of harmful algae blooms (HABs) have gradually increased, posing a serious threat to human health, marine ecosystems and economic development. For early warning, a method is required that can quickly detect and monitor microalgae. It is proposed to use aptamer targeted to Prorocentrum minimum, along with exonuclease III (Exo III), gold nanoparticles, target single-stranded DNA and hairpin structure probe to construct a new method, i.e. aptamer-lateral flow dipstick (LFD) based on Exo III-assisted signal amplification assay (ALBEA). The key conditions, including signal amplification and LFD detection, are optimized. Under the optimal conditions, the detection limit of ALBEA was 1.25 cells mL⁻¹. The cross-reactivity test showed no positive result except for P. minimum, indicating that the method is highly specific. The anti-interference test confirmed that the technique was not affected by the presence of other microalgae. The tested results of P. minimum cultured under different nutrient conditions and different growth stages demonstrated that the method is not affected by the cell state. Furthermore, the test results of simulated natural water samples further validated the practicality of the ALBEA. In conclusion, the established ALBEA offers a sensitive, specific and user-friendly tool, which can be used for the rapid detection of P. minimum and also provides a reference for the detection of other microalgae.