A novel electrochemical sensor based on MOFs composites, gold nanoparticles, and DNAzyme for Cu2+ sensitive detection

Due to industrial and agricultural activities, excessive copper ions have been released into the environment, leading to adverse effects on human health. It is essential to develop a rapid and efficient detection technology for Cu2+. In this study, a novel electrochemical DNA sensor was constructed, in which Fe-MIL-101 was used as a modified material for the substrate electrode, gold nanoparticles were electrochemically deposited, and DNAzyme was applied as a probe to recognize Cu2+ specifically. Differential pulse voltammetry was selected to detect Cu2+ concentration. Optimal conditions were established with DNAzyme concentration of 1 μmol, incubation time of 5 min, fixation time of 16 h, and reaction time of 30 min. Under optimal conditions, the detection range of Cu2+ concentration was 5 × 10−11∼5 × 10−5 M, and the detection limit was 10−12 M Cu2+ (3δ). It had good repeatability, stability, and reproducibility. Various interference anions and organic matter had little influence on Cu2+ detection, and the sensor showed great anti-interference ability. The sensor was used to detect Cu2+ in the actual soil solution using spike recovery method. The recovery rate of the samples was 93–103.6 %. Overall, the sensor had good detection ability and environmental adaptability, and could specifically detect Cu2+ in soil solution.