Magnetically induced self-assembly DNAzyme electrochemical biosensor based on gold-modified-FeO/FeOheterogeneous nanoparticles for sensitive detection of Ni.

A magnetically induced self-assembly DNAzyme electrochemical biosensor based on gold-modified-FeO/FeOheterogeneous nanoparticles was successfully fabricated to detect Nickel(II) (Ni). The phase composition and magnetic properties of-FeO/FeOheterogeneous nanoparticles controllably prepared by the citric acid (CA) sol-gel method were investigated in detail. The-FeO/FeOheterogeneous nanoparticles were modified by using trisodium citrate as reducing agent, and the magnetically induced self-assembly-FeO/FeO-Au nanocomposites were obtained. The designed Ni-dependent DNAzyme consisted of the catalytic chain modified with the thiol group (S1-SH) and the substrate chain modified with methylene blue (S2-MB). The MGCE/-FeO/FeO-Au/S1/BSA/S2 electrochemical sensing platform was constructed and differential pulse voltammetry was applied for electrochemical detection. Under the optimum experimental parameters, the detection range of the biosensor was 100 pM-10M ( = 0.9978) with the limit of detection of 55 pM. The biosensor had high selectivity, acceptable stability, and reproducibility (RSD = 4.03%).