The Synthesis And Modification Of MnFe₂O₄ Nano-clusters And Its Application In Immunochromatographic Detection Of D-dimer

Due to its wide range of applications in magnetic resonance imaging,biomacromolecule separation,magnetic hyperthermia and immunochromatographic detection,MnFe₂O₄nanoparticles with uniform size and high saturation magnetization become one of the hot topics in the field of materials research.In this thesis,super-paramagnetic MnFe₂O₄nano-clusters with good dispersibility and high saturation magnetization were prepared by high-temperature thermal decomposition of Fe?acac?₃ and Mn?acac?₂ under argon atmosphere.Its saturation magnetization is up to 85 emu/g.Then by ligand exchange method,the surface of nanoparticles was completely covered by 3,4-dihydroxyhydrocinnamic acid?DHCA?molecules,and MnFe₂O₄ nano-clusters can be well dispersed in water and buffers.And the surface of nano-clusters was rich in carboxyl functional groups,laying the foundation for biological applications.The obtained MnFe₂O₄ nanoclusters were used as biological probes to establish lateral flow immunochromatography assay?LFIA?for rapid quantitative detection of D-dimer in the range of 0.05–6?g/mL.The detail results were obtained as follows:?1?Preparation of oil phase MnFe₂O₄ nanocluster particlesUsing high-temperature thermal decomposition method,Fe?acac?₃ and Mn?acac?₂ as precursors,oleic acid as reactant and octadecene as solvent,MnFe₂O₄ nanoparticles with different sizes and shapes were prepared by adjusting the concentration of the precursors.MnFe₂O₄ nanoparticles were characterized by SEM,TEM,XRD,FTIR,TGA,VSM.MnFe₂O₄ nano-clusters with superparamagnetism and high saturation magnetization were synthesized.TEM results show that the synthesized nano-clusters have particle size of 47.3nm.They are composed of small particles with particle size of 8.2 nm.The VSM results show that the saturation magnetization of nano-cluster is 85emu/g.?2?The phase transfer of MnFe₂O₄ nano-clusters The aqueous phase transfer and carboxyl modification of the oil phase MnFe₂O₄ nano-clusters was performed by using DHCA ligand exchange method in one step.With tetrahydrofuran as the single-phase reaction solvent,MnFe₂O₄ nano-cluster particles in the oil phase were transferred into the aqueous phase.The FTIR spectroscopy of product indicated that the particles were successfully modified with carboxyl group.?3?Application of MnFe₂O₄ nano-clusters in the quantitative detection of D-dimer by immunomagnetic chromatographyMnFe₂O₄ nano-cluster was selected as the label in lateral flow immunochromatography assay.First,the chromatographic strips with different pore size NC membranes were prepared to optimize the NC membrane of the strip.And the lateral flow immunochromatography assay with MnFe₂O₄ nano-clusters as the carrier was established.The qualitative and quantitative detection of D-dimer in the serum was achieved.The experimental results showed that MnFe₂O₄ nano-clusters with high saturation magnetization can be well applied to the immunomagnetic system.We plotted the standard curve by plotting the ratios of the magnetic signal values of the test and control lines?T/C?to the concentrations of D-dimer and obtained the fitting parameters using a logarithmic function equation with a correlation coefficient of R²=0.9926,indicating that the quantitative assessment feasibility.Specific experiments showed that other interferences in the blood had no significant effect on the D-dimer assay.