The Preparation And Application In Magnetic Resonance Imaging Of Iron-based Nanocomposites

In this paper,two series of iron-based nanocomposites with different core-shell and inlay-type structures were synthesized with cheap,easily available,non-toxic iron compounds as raw materials,and the iron-based composites may be the effective candidate of theranostic magnetic resonance imaging?MRI?contrast agent.Iron nanoparticles encapsulated by carbon?Fe@C?have been prepared in large scale with the liquid acrylonitrile oligomer?LANO?as the reducing agent and the protective layers and the Fe₂O₃ nanoparticles as the iron source via the synthesized technique of thermal reduction combined with carbonization.The high resolution transmission electron micrograph?HRTEM?results demonstrated that the synthesized nanocomposites exhibited the core-shell structure with the homogeneous body centered cubic iron as core coated by the carbon shell with thickness of 6-23 nm.The XRD pattern confirmed that the carbon encapsulated layers of Fe@C could significantly protect the iron nanoparticles against air oxidation and erosion of acid or base.Moreover,the vibrating sample magnetometer?VSM?tests confirmed that the effective saturation magnetization of Fe@C nanocomposites were estimated to be 184.347 emu/g and the corresponding iron core were soft ferromagnetic behavior.To expanding the application of the Fe@C nanoparticles,these nanoparticles can be solubilized in water by the non-specific physical attachment of sodium dodecylbenzene sulfonate?NaDDBS?under ultrasonication.The NaDBBS-functionalized Fe@C nanoparticles?Fe@C@NaDBBS?have been proved by XRD,SEM,TEM,VSM and MTT,photothermal experiment to have hydrophilicity,ferrimagnetism,chemical stability,good biocompatibility,photothermal effect,and transverse relaxivity?r₂?,which indicated that the nanocomposites might be promising candidate for theranostics MRI contrast agents;The nanocomposites G-Fe₃O₄ with mosaic structure formed by the uniform and extremely small-sized Fe₃O₄ nanoparticles anchoring in graphene have been successfully prepared via a facile coprecipitation method using graphene as the raw material.The amount of Fe₃O₄ loading on graphene was estimated to be 52 wt.%.The obtained G-Fe₃O₄ nanocomposites exhibit excellent chemical and thermal stability,conductivity,supraparamagnetism,good biocompatibility and r₂ relaxivity.In order to improve the hydrophilicity of the nanocomposites furtherly,aniline was added simultaneously during the preparation,the hydrophobic nanocomposites could be easily transformed to hydrophilic functionalized nanocomposites G-Fe₃O₄-PAN with mosaic structure through polymeric and chemical co-precipitated solution-processing.The Fe₃O₄ nanoparticles dispersed homogeneously on the surface of graphene sheets and capped by the formed polyaniline?PAN?in G-Fe₃O₄-PAN nanocomposite.The loading of Fe₃O₄ among the nanocomposite was estimated to be 62 wt.%.The G-Fe₃O₄-PAN nanocomposites exhibit the integrated properties of superior electrical conductivity,superparamagnetism,oxidation resistance,thermal stability,water solubility,magnetic sensitivity and cell compatibility,as well as the obvious photothermal and magnetic resonance imaging contrast effect,which indicates that G-Fe₃O₄-PAN may be used in cancer theranostics.The functionalized hydrosoluble nanocomposites GO-Fe₃O₄-PPy with mosaic structure were successfully fabricated by two-step solution method using synthesized graphene oxide as the raw material.The formed polypyrrole could stack and coordinate with the Fe³⁺on graphene oxide followed by segregation and fixation of Fe₃O₄ nanoparticles.In GO-Fe₃O₄-PPy nanocomposites,Fe₃O₄ nanoparticles dispersed uniformly on the surface of graphene oxides and coated by the formed polypyrrole with the loading capacity of Fe₃O₄ on GO was range from38.20 to 70.62 wt.%.This nanocomposite also exhibits superior hydrophilic,electrical conductivity,superparamagnetism and magnetic response,oxidation resistance,transverse proton relaxivity value,which may be used as MRI contrast agents.The mosaic GO-FeP-Fe₃O₄ nanocomposites with FeP,FeP₂ and Fe₃O₄ nanoparticles loaded on GO were prepared through in-situ phosphidation reaction of pre-prepared GO-Fe₃O₄with phosphine?PH₃?gas at 300?C.The GO-FeP-Fe₃O₄ nanocomposites exhibit magneism and good electrocatalytic performance in hydrogen evolution reaction?HER?that may be further developed as recyclable electrocatalyst for HER.