Phoxim-specific DNA aptamer screening, characterization and application in a multiple complementary strands fluorescent aptasensor

In order to develop a fluorometric aptamer-based biosensor for ultrasensitive and selective detection of phoxim, a modified magnetic beads-systematic evolution of ligands by exponential enrichment (MB-SELEX) method was used in this study to select phoxim aptamer. An aptamer (APT3) that bonded to phoxim with high affinity was obtained after 15 rounds of selection, which had dissociation constant (Kd) of 0.93 ​± ​0.25 ​μM. A fluorometric aptasensor was then developed and enhanced the sensitivity and selectivity of phoxim detection based on APT3, multi-complementary strands (CS) and gold nanoparticles (AuNPs). This method had a good linear range of 0.05–5 ​μM, and detection limit was as low as 29.69 ​nM for phoxim. In addition, the aptasensing specifically captured phoxim in a variety of pesticides and real samples. The herein results proved that the method can be applied in practical detection. [Display omitted] •An aptamer (APT3) that bonded to phoxim with high affinity was obtained after 15 rounds of selection, which had Kd of 0.93 ​± ​0.25 ​μM.•A fluorescent aptasensor based on multi-complementary strands structure and AuNPs was fabricated.•This method had a good linear range of 0.05–5 ​μM, and detection limit was as low as 29.69 ​nM for phoxim.