Selection, Characterization, and Biosensing Application of High Affinity Congener-Specific Microcystin-Targeting Aptamers

The efficiency of current microcystin detection methods has been hampered by the low detection limits required in drinking water and that routine detection is restricted to a few of the congeners with high degree of undesired cross-reactivity. Here, we report the development of novel microcystin-targeting molecules and their application in microcystin detection. We have selected DNA aptamers from a diverse random library that exhibit high affinity and specificity to microcystin-LR -YR, and -LA. We obtained aptamers that bind to all chosen congeners with high affinity with K-D ranging from 28 to 60 nM. More importantly, we also obtained aptamers that are selective among the different congeners, with selectivity from 3-folds difference in binding affinity to total discrimination (K-D of 50 nM versus nonspecific binding). Electrochemical aptasensors constructed with the selected aptamers were able to achieve sensitive and congener-specific microcystin detection with detection limit as low as 10 pM.