Aptamer-Mediated Fluorescent Copper Nanoclusters for Label-free and Rapid Detection of Isocarbophos

Based on the target recognition ability of aptamer and the excellent fluorescence performance of copper nanoclusters (CuNCs), a label-free fluorescent probe was developed for rapid detection of isocarbophos (ISO). In the absence of target molecule, the aptamer DNA and complementary DNA in the solution formed double-stranded DNA, which could mediate the synthesis of fluorescent CuNCs and showed a high fluorescence signal. When ISO was present, it would form aptamer-target complex, and released the complementary DNA. Free single stranded DNA could not mediate the synthesis of CuNCs, resulting in weak fluorescence signal in solution. Under the optimal conditions, the fluorescence inhibition rate of the system showed a linear relationship with the logarithm of concentration of ISO within the concentration range of 0.05-25 mg/L, and the detection limit was 47 mu g/L (3 sigma). The method showed a high selectivity in detection of ISO with little interference. In addition, the probe was successfully used for detection of ISO in water samples with the recoveries of 80.3%-108.0%. These results indicated that the developed method could be used to effectively detect ISO residues in actual samples.