A detection method for Prorocentrum minimum by an aptamer-gold nanoparticles based colorimetric assay

Here, to give early waring for harmful algal blooms caused by Prorocentrum minimum, we reported a simple and rapid colorimetric assay that is named aptamer-gold nanoparticles (GNPs) based colorimetric assay (AGBCA). The GNPs maintain a dispersed state and have a strong characteristic absorption peak at 520 nm. With the addition of NaCl, the stability of the solution will be destroyed and the dispersed GNPs will aggregate. Therefore, the characteristic absorption peak of the GNPs solution will change from 520 nm to 670 nm. Aptamers can be adsorbed on the surface of GNPs, effectively preventing the aggregation of GNPs. In the presence of P. minimum, aptamers will specifically bind to P. minimum, causing the dissociation of the aptamers from GNPs. Consequently, the GNPs will aggregate in the NaCl solution, corresponding to a new absorption peak at 670 nm. A linear relationship between the absorbance ratio variation (Delta A670/A520) and the P. minimum concentration was observed in the concentration range of 1 x 102 -1 x 107 cells mL-1, with a low detection limit of 8 cells mL-1. The developed AGBCA is characterized by simplicity, strong specificity, and high sensitivity and is thus prom-ising for the quantitative detection of P. minimum in natural samples.