A facile luminescence resonance energy transfer method for detecting cyano-containing pesticides in herbal medicines

It is urgently demanded to establish facile and rapid methods for screening pesticide residues in cultivated herbal medicines to guarantee drug safety. Herein a fluorescent (FL) method was constructed for detecting cyano-containing pesticides by employing the luminescence resonance energy transfer (LRET) behavior between up-conversion nanoparticles (UCNPs) and gold nanoparticles (AuNPs). Negatively-charged citrate-capped AuNPs can be adsorbed onto the surface of positively-charged amino-modified UCNPs by an electrostatic interaction. It resulted in decrease of the FL signal of UCNPs through the LRET process. Cyano-containing pesticides can bind with AuNPs via Au-N=C metal-ligand coordination and remove citrate from the surface of AuNPs. The replacement process induced aggregation of AuNPs and inhibition of LRET. Thus the pesticides can be detected by a facile procedure within 6 min. Acetamiprid, fenpropathrin and chlorothalonil were adopted as model analytes to study the feasibility of the EL method for the detection of cyano-containing pesticides. With the optimum conditions, acetamiprid, fenpropathrin and chlorothalonil can be detected within the ranges of 0.10-100 ng mL(-1), 1.0-100 ng mL(-1) and 0.10-50 ng mL(-1), with detection limits of 0.015 ng mL(-1), 0.24 ng mL(-1) and 0.011 ng mL(-1), respectively. It has been successfully employed to detect acetamiprid in Lanceotata, Angelica dahurica and Astragalus with acceptable recovery values of 76.0%-120.0%, demonstrating its potential for practical application. The work provides a highly efficient methodologic platform for screening pesticide residues in herbal medicines.