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

Nano-scaled Fe 3 O 4 were synthesized using solvothermal synthesis, and amino-modification of nano-scaled Fe 3 O 4 was conducted with APTES. With Fe 3 O 4 -NH 2 and Zn 2+ 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 @Fe 3 O 4 ) 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 @Fe 3 O 4 looked like a nanoflower. The mimetic peroxidase properties of Zn-(PDC) 2 @Fe 3 O 4 were studied with H 2 O 2 solution and TMB solution as the substrates, and the results showed that: the Michaelis constant of H 2 O 2 by Zn-(PDC) 2 @Fe 3 O 4 was: K m  = 0.411 mM, the maximum reaction rate: v max  = 3.440 × 10 −8  M s −1 ; the Michaelis constant of TMB by Zn-(PDC) 2 @Fe 3 O 4 was: K m  = 0.189 mM, and the maximum reaction rate: v max  = 2.419 × 10 −8  M s −1 , both of which were lower than those of H 2 O 2 and TMB by Fe 3 O 4 and Horseradish Peroxidase (HRP). Based on the reduction of the absorbance of original solution due to the consumption of H 2 O 2 in oxidation-reduction reaction between SO 3 2− and H 2 O 2 under acid conditions, a new method for determining the content of SO 3 2− was established. The linear range of SO 3 2− was 8 × 10 −7 ∼8 × 10 −5  mol/L, the detection limit of SO 3 2− was 8 × 10 −8  mol/L, and the RSD of SO 3 2− was 2.7–9.2%.