Surface Organic Modification Of Fe₃O₄@MWNTs And Study On Their Cytophagy,Electromagnetic Shielding And Wave Absorption Properties

Carbon nanotubes are widely used in the field of biomedicine,electromagnetic shielding,and microwave absorption due to their easy functionalization,good stability,and high dielectric properties.However,because of mutual physical entanglement and van der Waals forces,the dispersion of tubes is poor,which greatly reduces the application effect in related fields.How to realize the application effectiveness of carbon nanotubes in tumor-targeted therapeutic vectors and electromagnetic shielding and microwave absorption has become a research hotspot in recent years.In this topic,magnetic carbon nanotubes(Fe3O4@MWNTs)filled with Fe3O4 particles were successfully prepared by hydrothermal reflow method,and the surface modification of Fe3O4@MWNTs with fluorescence modification was performed by ATRP method.Two kinds of fluorescent magnetic carbon nanotubes with magnetic response and fluorescent tracer imaging was integrated.On this basis,the phagocytic behavior of Fe3O4@MWNTs-FITC and the influence of Fe3O4@MWNTs-PGMA content and orientation on the electromagnetic shielding and microwave absorbing properties of its composites was studied.The main work was as follows:(1)A carboxylated magnetic carbon nanotubes(Fe3O4@MWNTs-COOH-1)filled with Fe3O4 particles was first prepared based on a hydrothermal refluxing method and an acidifying oxidation method,and then FITC labeled magnetic tubes(Fe3O4@MWNTs-FITC)and RhoB labeled magnetic tubes(Fe3O4@MWNTs-RhoB)were successfully prepared using an ATPP method and a fluorescent labeling method.Fluorescence spectrophotometer(FS),ultraviolet-visible-near-infrared spectroscopy(UV-Vis),laser confocal microscopy(CLSM)and other characterization tests showed that the obtained Fe3O4@MWNTs-FITC-1 and Fe3O4@MWNTs-RhoB-2 has remarkable green fluorescence and red fluorescence,respectively,and has strong magnetic response.Further study found that the carboxylated magnetic carbon tubes(Fe3O4@MWNTs-COOH-2)prepared preferentially by the first acidification oxidation method and then the hydrothermal reflux method showed a higher magnetic response,and it's fluorescent labeled magnetic tubes Fe3O4@MWNTs-FITC-2 and Fe3O4@MWNTs-RhoB-2 had superior fluorescence imaging properties.(2)On the basis of successful preparation of Fe3O4@M WNTs-FITC-1 and Fe3O4@MWNTs-FITC-2 with different magnetic and fluorescence properties,the influence of different organic coating thickness on the dispersion of fluorescent carbon nanotubes was compared.SEM and DLS tests showed that the agglomerates of Fe3O4@MWNTs-FITC-1 and Fe3O4@MWNTs-FITC-2 were small in size and good in dispersibility.Using the above two fluorescence-modified carbon nanotubes as the desired targeting vectors,the biological behavior of tumor cells phagocytosed was explored.Fluorescence microscopy(FM)and CLSM measurements showed that smaller MWNTs aggregates of Fe3O4@MWNTs-FITC-1 and Fe3O4@MWNTs-FITC-2 were phagocytized into cells.Due to magnetic stimulation,the phagocytosis effect of Fe3O4@MWNTs-FITC-2 with higher magnetic content was significantly greater than that of Fe3O4@MWNTs-FITC-1.(3)The influence of Fe3O4@MWNTs-PGMA content on the EMI shielding and wave absorption properties of wax composites and epoxy composites was systematically investigated.The results showed that the increase of Fe3O4@MWNTs-PGMA content would improve the shielding effectiveness of composites.As a dielectric loss type material,MWNTs and a magnetic loss material such as Fe3O4 were combined to achieve a synergy effect of a multi-loss mechanism to obtain higher matching impedance and good absorbing effect.Therefore,the absorbing effect of Fe3O4@MWNTs-PGMA/wax composites was better than that of MWNTs composites.With the increase of Fe3O4@MWNTs-PGMA absorbents,the composites have higher absorption attenuation values and the absorption peaks shifted to low frequencies.