A sensitive electrochemical sensor for the detection of Pb2+ was developed based on PtNPs@Cu-MOF signal probe and DNA walker signal amplification. The electrochemical sensor can be used for the detection of Pb2+ based on the recognition of rA site in DNA walker-Substrate Strand (SS). The SS mixture is assembled on the AuE surface through the Au-S bond and can split and form two single chains S1 and S2 for the DNA walker reaction. Most importantly, The DNA walker can move automatically and participate in the next part cycle for the signal amplification. Furthermore, for an excellent electrochemical signal PtNPs@Cu-MOF nanocomposite was introduced in electrochemical sensor based on the effect between S1 chain and HP hairpin structure. This nanocomposite can provide a larger specific surface, adhesion sites and excellent electrical conductivity for the sensor. This sensitive electrochemical sensor showed that the concentration of Pb2+ presented a linear correlation range from 3 × 10-12 to 5 × 10-6 mol/L and the limit of detection (LOD) was 0.2 pmol/L. The designed sensor has a good recovery in two real samples of tap water and orange juice, indicating it can be used as an alternative detection method via comparison with other detection method. The sensor displayed a promising possibility in actual monitoring.
Keywords: DNA walker signal application; Electrochemical sensor; Lead ion; Metal-organic framework.
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