A novel enhanced electrochemical sensor based on the peroxidase-like activity of Fe3O4@Au/MOF for the detection of p-aminophenol

A new type of composite metal–organic framework (Fe3O4@Au/MOF) nanoparticle was prepared by self-assembly method, which had the recyclability of Fe3O4 magnetic particles (Fe3O4NPs) and the advantage of gold nanoparticles (AuNPs) that could accelerate electron transfer. In addition, the mimic enzyme activity of Fe3O4@Au/MOF has been significantly increased because of the presence of Fe3O4NPs and AuNPs. Then physical and chemical characterization of the composite nanoparticle was carried out through advanced technologies, such as Fourier transform infrared spectroscopy, transmission electron microscope and X-ray photoelectron spectroscopy. Finally, based on the peroxidase-like activity enhanced by Fe3O4@Au/MOF composite nanoparticle, a highly specific enzyme-free electrochemical sensor was prepared for the detection of p-aminophenol. The results showed that the optimal catalytic system was the reaction temperature of 50 °C, the addition amount of Fe3O4@Au/MOF of 0.005 g, scanning rate of 0.1 V s−1, and buffer solution pH 5. The working curve equation is |Ipa|= 2.7372C + 2.1068, R2 was 0.9952, and the minimum detection limit was 0.38 μmol L−1 (S/N = 3) when the p-aminophenol concentration was located in the range of 0.1–10 mmol L−1. The detection system possessed an excellent recovery rate and anti-interference. In addition, the proposed method was validated to determine p-aminophenol in water samples with satisfactory results.Graphical abstract