Broad-Spectrum Aptamer Selection of Challenging Retronecine-Type Hepatotoxic Pyrrolizidine Alkaloids for Biosensor Construction

Since hepatotoxic pyrrolizidine alkaloids (HPAs) are a group of phytotoxins widely distributed all over the world, it is important to develop a fast and economical detection method to monitor HPA levels. Given that the aptamers are powerful recognition elements for sensing platform construction, herein we have isolated four HPA-binding aptamers for the first time using the library-immobilized systematic evolution of ligands by the exponential enrichment (SELEX) strategy. All of the selected aptamers could recognize retronecine-type HPAs and had excellent selectivity over other interferents. Two of the obtained aptamers were used to develop a strand-displacement fluorescent sensing platform that successfully detected 10 HPA chemicals in honey and tea samples, demonstrating the great potential of the selected aptamers in the application of safety evaluation in food, agriculture, medicine, and other fields. This work also provides new ideas for broad-spectrum aptamer selection for other challenging targets (with few functional groups and hydrophobic properties) using natural nucleic acid libraries.