Ultrasensitive "signal-on" electrochemical aptasensor for assay of acetamiprid residues based on copper-centered metal-organic frameworks.

In present work, a versatile "signal-on" electrochemical aptasensor with ultra-sensitivity and high selectivity for detecting acetamiprid residues has been successfully constructed. Electrochemistry behaviors of as-synthesized copper-centered metal-organic frameworks (CuMOF) on various electrodes were investigated in details. The results indicated that CuMOF exhibited well-behaved redox events. Thus, we used Au-CuMOF as signaling element to label probe DNA (pDNA). The gold nanoparticles-reduced graphene oxide (Au-rGO) has a high specific surface area and excellent conductivity, which was utilized to immobilize complementary strand (cDNA). In the presence of acetamiprid, Au-CuMOF-labeled pDNA would hybridize with the exposed cDNA, allowing CuMOF to approach the electrode and produce a sensitive signaling current. Such a "signal-on" method does not suffer from the drawbacks of "signal-off" methods. The linear range of this proposed electrochemical aptasensor was 0.1 pM-10.0 nM and the detection limit was as low as 2.9 fM. This platform exhibited wonderful selectivity, stability, and repeatability, and was successfully applied to detect acetamiprid residues in tea samples exhibiting enormous practical application potential.