Preparation and application of magnetic zinc pyridinedicarboxylic acid nanocomposite (Zn-(PDC)2@Fe3O4)

Nano-scaled Fe3O4 were synthesized using solvothermal synthesis, and amino-modification of nano-scaled Fe3O4 was conducted with APTES. With Fe3O4-NH2 and Zn2+ as the metal centers, 2,6-pyridinedicarboxylic acids as the organic ligand, and using the one-step ultrasonic-assisted method, a new magnetic zinc pyridinedicarboxylic acid nanocomposite (Zn-(PDC)2@Fe3O4) was synthesized. The structure, composition and morphology of the products were characterized using methods such as X-ray single crystal diffraction, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction, and scanning electron microscope. The results showed that the Zn-(PDC)2 was almost an octahedron, and the Zn-(PDC)2@Fe3O4 looked like a nanoflower. The mimetic peroxidase properties of Zn-(PDC)2@Fe3O4 were studied with H2O2 solution and TMB solution as the substrates, and the results showed that: the Michaelis constant of H2O2 by Zn-(PDC)2@Fe3O4 was: Km = 0.411 mM, the maximum reaction rate: vmax = 3.440 × 10−8 M s−1; the Michaelis constant of TMB by Zn-(PDC)2@Fe3O4 was: Km = 0.189 mM, and the maximum reaction rate: vmax = 2.419 × 10−8 M s−1, both of which were lower than those of H2O2 and TMB by Fe3O4 and Horseradish Peroxidase (HRP). Based on the reduction of the absorbance of original solution due to the consumption of H2O2 in oxidation-reduction reaction between SO32− and H2O2 under acid conditions, a new method for determining the content of SO32− was established. The linear range of SO32− was 8 × 10−7∼8 × 10−5 mol/L, the detection limit of SO32− was 8 × 10−8 mol/L, and the RSD of SO32− was 2.7-9.2%.