Cationic polyelectrolyte as powerful capture molecule in aptamer-based chromatographic strip for rapid visual detection of paraquat residue in agricultural products

Although methods based on mass spectrometry or immunoassays can meet the demands of paraquat detection, their application is limited by a lack of convenience or stability. Herein, a facile visual aptamer-based chromatographic strip (CS) was fabricated for the rapid paraquat detection using the cationic polyelectrolyte poly(diallyl dimethyl ammonium chloride) (PDDA) as a powerful capture molecule at test-line (T-line). The PDDA could capture the gold nanoparticles (AuNPs) through strong electrostatic interactions for visual detection. The proposed CS showed an excellent response for paraquat in the range of 20–150 μg·L −1 , and the limit of detection (LOD) was as low as 4.28 μg·L −1 . This detection method has good stability and specific selectivity , and can visually determine paraquat residues more than 30 μg·L −1 by naked eye within 3 min. The results demonstrated that the prepared CS based on aptamer and cationic polyelectrolyte is an accurate and practicable tool for rapid analysis of pesticide residues .