Aptamer-driven upconversion fluorescence detection of dual pesticide residues in tea

Pesticide residues in tea pose a significant risk to food safety and human health, calling for sensitive and specific analytical methods capable of multi-residue detection.In this study, a dual-aptamer fluorescence sensor was developed based on fluorescence resonance energy transfer (FRET) between upconversion nanoparticles (UCNPs) and gold nanoparticle–aptamer conjugates (AuNPs-Apt) for the multi-residue detection of dimethoate and thiram. The competitive binding of target pesticides to AuNPs-Apt triggered their displacement from magnetic nanoparticle-cDNA complexes (MNPs-cDNA), enabling magnetic separation and individual quantification. The sensor exhibited high sensitivity, with detection limits of 0.0019 ng/mL for dimethoate and 0.0029 ng/mL for thiram, and wide linear ranges of 0.01–100 ng/mL and 0.01–500 ng/mL, respectively. The method was successfully applied to tea samples, confirming its reliability and potential utility for pesticide monitoring in food safety applications.