Selection and characterization of DNA aptamers specific to trichlorfon.

In this study, six candidate DNA aptamers specific to trichlorfon were successfully obtained through 16 rounds of capture-SELEX. Their binding affinities were rigorously evaluated and comparatively analyzed using three orthogonal techniques: quantitative real-time polymerase chain reaction (qPCR), gold nanoparticle-based colorimetric assay (AuNP assay), and SYBR Green I (SGI)-mediated fluorescence assay. Among these identified aptamers, APTri-7 exhibited the highest binding affinity, with a dissociation constant (Kd) of 0.597 ± 0.206 µg mL-1. Subsequently, using APTri-7, a highly sensitive electrochemical sensor was developed based on poly-L-lysine-black phosphorus (PLL-BP) and gold nanoparticles (AuNPs). Under optimal conditions, the biosensor demonstrated a linear range from 1 pM to 100 nM. Moreover, selectivity assessment against other pesticides, including carbaryl, dibrom, isoprocarb, and fenthion, confirmed the sensor's high specificity toward trichlorfon. The recovery rates of the aptasensor for tap water samples ranged from 89.37% to 106.2%, demonstrating its great potential in practical applications.