An electrochemical aptasensor of malathion based on ferrocene/DNA-hybridized MOF, DNA coupling-gold nanoparticles and competitive DNA strand reaction

A novel electrochemical aptamer sensor platform for malathion detection was successfully constructed based on nanocomposite probe. The zirconium-based metal organic framework (MOF) was synthesized by hydrothermal method, and was coupled with complementary probe (CP) and carboxy-ferrocene (Fc-COOH) by covalent bonds to form CP-MOF-Fc nanocomposite probe. The complex probe hybridized with malathion aptamer on electrode by complementary base-pairing reactions. On account of the stronger affinity of the aptamer to target, CP-MOF-Fc was released into the buffer solution, causing a decrease in the DPV signal of Fc. Under optimized conditions, the prepared sensor showed a linear range of 25–850 ng L −1 toward malathion with a detection limit of 17.18 ng L −1 (S/N = 3) due to the high specific surface area of MOF , showing the excellent ability of signal amplification. In addition, it exhibited good repeatability and excellent selectivity. In the real sample experiment, satisfactory spike recovery results were obtained from 95.00 to 103.16%. The proposed strategy exhibited a rosy prospect in aptamer sensor design for pesticide testing.