A novel electrochemical sensor of DNAzyme/AuNPs/Fe/ZIF-8/GCE for Pb2+ detection in the soil solution with enhanced sensitivity, anti-interference and stability

In recent years, lead (Pb) contaminated soil has caused irreversible damage to human beings. It is urgent to develop a novel technology for accurate detection of Pb in the soil solution. Herein, a new electrochemical sensor was fabricated. Fe/ZIF-8 was used as the modification material, gold nanoparticles (AuNPs) were electrodeposited, and DNAzyme was applied on the surface as the probe. Under the optimum conditions (DNAzyme concentration of 1 μmol, fixation time of 4 min, incubation time of 17 h and reaction time of 30 min), the detection range was 5×10−12 ∼ 5×10−5 M, and the minimum detection limit was 10−13 M (3δ). Furthermore, the electrochemical sensor demonstrated outstanding anti-interference ability to common cations, anions, organic compounds and other interference factors. After four consecutive tests, the relative standard deviation (RSD) was only 0.39%, and it still displayed excellent reproducibility with 0.69% of RSD. After 20 days, the sensor's response to Pb2+ remained at 93.58%. In addition, the sensor could accurately detect Pb2+ in the actual soil solutions, and the recoveries of the samples ranged from 92% to 109.4%. In conclusion, this electrochemical sensor can specifically detect Pb2+ in the soil solution with enhanced sensitivity, anti-interference capability and stability, which is of great significance for Pb2+ detection in the field.