Magnetic Induction Heat Effect And Enzyme Activity Of Fe₃O₄ Nanoparticles In Active/Passive Diffusion Media Under Alternating Magnetic Field

Magnetic nanoparticles,with special magnetic properties and good biosafety,are used in magnetic induction hyperthermia,and their inherent enzymatic properties can be used as nanozymes.In this thesis,the construction of alternating magnetic field generator was designed and completed.The effect of alternating magnetic field on the magnetic induction heat and enzyme-like properties of Fe₃O₄ nanoparticles was studied.The main research contents and results are as follows（1）Preparation and characterization of the Fe₃O₄ nanoparticles.The Fe₃O₄ nanoparticles were prepared in the organic phase under high temperature decomposition.Conversion of nanoparticles from hydrophobic to hydrophilic by the ligand exchange methods.The results of material characterization showed that the size of Fe₃O₄ nanoparticles prepared by adjusting the amount of precursors were 6 nm,11 nm and 16 nm,respectively.The morphology was uniform,well dispersed and superparamagnetic.（2）Construction of alternating magnetic field generator.A set of alternating magnetic field generator is built.By adjusting the current,the magnetic field strength can be adjusted from 0-500 Gs,and the frequency can be adjusted by changing different coils to achieve200-500 KHz.（3）Study on the magnetic induction heat of Fe₃O₄ nanoparticles by alternating magnetic field.The SAR（Specific Absorption Power Rate）values of Fe₃O₄ with diameters as 6 nm,11 nm and 16 nm in alternating magnetic field were studied.The SAR values of Fe₃O₄nanoparticles with different volume fractions of Escherichia coli were studied too.Comparison of the addition of active/inactive bacteria reveals that active bacteria can increase the SAR value of the particles up to 42.9%.（4）Study on the enzyme-like properties of Fe3O4 nanoparticles by alternating magnetic field:Improved alternating magnetic field equipment for real-time detection of enzyme activity.The properties of bi-substrate hydrogen peroxide and o-phenylenediamine catalyzed by Fe₃O₄ nanoparticles under alternating magnetic field were studied.The change of catalytic constant Kcat under alternating magnetic field with field strengths of 0Gs,115 Gs and 223 Gs were analyzed.The presence of the alternating magnetic field can increase the catalytic efficiency which was increased by 21%at 115 Gs;however,However,there is no linear relationship between field strength and catalytic efficiency.