Aptamer discovery via GO-SELEX and GrNP-SELEX for monocrotophos and its comparative analysis.

The selection of high-affinity aptamers for small-molecule detection is a critical challenge in biosensor development. This study introduces a graphene nanoplatelet-based SELEX (GrNP-SELEX) and compares its performance with the graphene oxide-based SELEX (GO-SELEX) for generating monocrotophos-specific aptamers. Characterization studies confirmed the successful adsorption of ssDNA onto both GO and GrNP, enabling effective selection. The best-performing aptamers, MPGO-130 and MPGR-999, exhibited Kd values of 31.14 µM and 19.92 µM, respectively, indicating a slightly higher affinity for GrNP-derived aptamers. These aptamers were integrated into an electrochemical biosensor, achieving limits of detection (LOD) of 0.58 ng/mL and 0.78 ng/mL and limits of quantification (LOQ) of 1.91 ng/mL and 2.60 ng/mL, respectively. The biosensors demonstrated effective detection of monocrotophos in real-world samples such as tomato extract, lake water, soil, animal feed, and meat extract, with validation performed using HPLC. While both SELEX strategies yielded functional aptamers, GrNP-SELEX emerged as a cost-effective and viable alternative. This study highlights the potential of GrNP-SELEX in aptamer development, contributing to the advancement of biosensing technologies for environmental and agricultural monitoring.