Detection of acetamiprid residues in vegetables by a self-enhanced bimetallic luminescent MOF-based electrochemiluminescence-electrochemistry dual-mode aptasensor

In this study, a dual-mode aptasensor based on the competition mechanism was constructed to detect acetamiprid (ACE) residues in vegetables. With 3,5-dicarboxyphenylboronic acid (5-bop) as a ligand, a bimetallic RuZn-based metal-organic framework (RuZn-MOF) was synthetized by applying a hydrothermal method to achieve efficient electrochemiluminescence (ECL) and electrochemistry (EC) dual-mode detection of ACE. Compared with the monometallic Zn-based metal-organic framework (Zn-MOF) of the same structure, the bimetallic RuZn-MOF exhibited a greater ability to transfer electrons due to the synergistic effect between different metal and the 5-bop ligand. Meanwhile, the complementary DNA (cDNA) probe for bonding the ACE aptamer was modified with ferrocene (Fc) and methylene blue (MB). When the target pesticide of ACE was present, ACE competed with the cDNA probe, so that the ECL achieved the "signal on" and the EC achieved the "signal off". ECL and EC detection being combined, the results showed that the two detection methods corroborated each other and worked synergistically, i.e., they effectively reduced the systematic errors and background signals, and improved the reliability of the detection. The linear ranges of the ECL and EC aptasensors were 1 pg/mL-1 μg/mL with the limit of detection (LOD) of 0.33 pg/mL, and 1 fg/mL-1 ng/mL with LOD of 0.33 fg/mL (S/N=3), respectively. The dual-mode strategy had good stability and specificity, providing some valuable support for the detection and analysis of other substances.