<?A3B2 tpl=13mm?><?A3B2 tpl=13mm?>A Thioflavin T-based Label-Free Fluorescent Aptasensor for Rapid Detection of Quinclorac Herbicide

A label-free fluorescent aptasensor based on thioflavin T (ThT) fluorescent probe was developed for rapid detection of quinclorac (QNC). In this sensor system, ThT specifically bound to the QNC aptamer Qapt-48nt with G-quadruplex structure, resulting in a significantly enhanced fluorescence signal. Upon addition of QNC, it competitively bound to Qapt-48nt, forming a QNC-Qapt complex and releasing free ThT, leading to a decrease in the fluorescence intensity of the system. Under optimal conditions, the linear detection range of this sensor for QNC was 0.012–4.84 μg/mL, the limit of detection (S/N=3) was 3.3 ng/mL, and the limit of quantification (S/N=10) was 9.8 ng/mL. This method was successfully applied to detection of QNC in river water, soil and rice samples, with recoveries ranging from 83.3% to 108.3% and relative standard deviations of 3.9% to 8.8%, and the results were comparable to those of HPLC-MS/MS method. The established aptasensor could complete the detection of QNC within 2 min, featuring simplicity, rapidity, and high specificity, and providing a novel method for rapid detection of QNC residues in environmental and food samples.