Dual functional G-quadruplex/β-cyclodextrin@AuNP/antibody probes for fluorescence assay of atrazine

This study presents a novel method for the highly sensitive and rapid detection of atrazine (ATZ) residues in water and food samples. This method overcomes the limitations of traditional detection techniques by ingeniously utilizing β -cyclodextrin ( β -CD)-modified gold nanoparticles. The excellent host-guest interactions of the cyclodextrin ring cavity were leveraged to achieve one-step co-conjugation of ssDNA and antibodies onto gold nanoparticles, resulting in a novel immunobiological detection platform for ATZ. By co-encapsulating G-quadruplex (G4) and anti-ATZ monoclonal antibody (mAb) on β -CD@AuNPs (DFP), the platform is endowed with dual functions of molecular recognition and signal amplification. After magnetic separation and enrichment of MMPs/DFP complexes, the G4 on DFP can efficiently catalyze the H 2 O 2 -mediated oxidation reaction of Amplex Red (in the presence of hemin and K + ). Experimental results show that the fluorescence intensity (excitation/emission, 530/588 nm) generated by this catalytic reaction exhibits a good linear relationship with atrazine concentration in the range of 0.01–100 ng·mL −1 (R 2  = 0.9878). More importantly, this method can be used to directly determine the concentration of atrazine in different samples without the need for complex pretreatment. Recovery rates range from 82.4 % to 114 %. This method offers a simple, sensitive and environmentally friendly solution, and provides a new idea for designing rapid sensing method for pesticide residue detection.