Development of an upconversion fluorescence DNA probe for the detection of acetamiprid by magnetic nanoparticles separation

An upconversion fluorescence DNA probe which consists of aptamer-conjugated magnet nanoparticles (apt-MNPs) and complementary DNA-conjugated upconversion nanoparticles (cDNA-UCNPs) was developed to detect acetamiprid. Acetamiprid can specifically conjugate with the apt-MNPs to dissociate the cDNA-UCNPs from the apt-MNPs and resulted in reduced fluorescence intensity through an external magnet. The change of fluorescence intensity (△I) is positively related to the concentration of acetamiprid, which can be applied for the quantification of acetamiprid. Under optimal conditions, a linear detection range and detection limit are 0.89-114.18 μg/L and 0.65 μg/L, respectively. The probe was successfully used to detect acetamiprid in spiked paddy water, soil, pear, apple, wheat and cucumber. Average recoveries are 78.2%-103.5% with intra-day relative standard deviations (RSDs) of 2.6%-10.9% and inter-day RSDs of 4.3%-10.2%. The amounts of acetamiprid in the authentic paddy water and pear samples detected by the DNA probe are significantly correlated with that detected by high-performance liquid chromatography (HPLC).