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 mu g/L and 0.65 mu g/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).