LAUSR

Copper ions (Cu2+) initiated carbon dots (CDs/Cu) with dual emissions were utilized to develop a ratiometric fluorescence sensor for ultrasensitive detecting inert thiophanate-methyl (TM). TM could be recognized by CDs/Cu through π-π stacking and could chelate Cu2+ of CDs/Cu through metal ions coordination, inducing synchronous fluoresent quenching of the dual-emission of CDs/Cu base on the excited state intramolecular proton transfer (ESIPT) and the ligand-to-metal charge transfer (LMCT). Fluorescence ratio of CDs/Cu (F416/F481) linearly responded in the TM concentration of 0.10 - 20.00 μmol/L with an ultralow limit of detection of 2.90×10-6 μmol/L. Synchronous response of the ratiometric sensor enhanced the specificity toward TM and presented remarkable capability of anti-interference in complex matrices. The sensor exhibited satifactory accuracy and precision for practical applications with recoveries of 88.33- 101.09% and RSDs of 1.61 - 5.06%, demonstrating an ultrasensitive ratiometric fluorescent nanosensor for detecting pesticides residues in complex matrices.