The Preparation And Application Of Polydopamine Modified Fe₃O₄ Core-shell Nanocomposites

Recent years,the magnetic Fe₃O₄ core/shell nanocomposites have become a hot research topic due to their great application prospects in biomedical fields such as targeted drug delivery,biomedical imaging,gene therapy vectors,and biomedical sensors.Polydopamine?PDA?is an excellent shell material with a large number of functional groups and good biocompatibility.The core/shell nanocomposites prepared by using polydopamine coated Fe₃O₄ core have various applications such as drug loading,photothermal therapy,noble metal nanoparticle loading,magnetic resonance imaging?MRI?and organic pollutant adsorption.However,due to the magnetic properties of the Fe₃O₄ core and the strong adhesion of the PDA shell,the prepared magnetic Fe₃O₄ core/shell nanocomposites are easily agglomerated,which affects various properties.Therefore,the development of a simple green synthesis method to prepare a polydopamine-coated magnetic Fe₃O₄ nanocomposite with good morphology and monodispersity has been an important task in this field.In order to prepare magnetic Fe₃O₄ nanocomposites with good performance,we have successfully synthesized a variety of Fe₃O₄ core/shell nanocomposites loaded with noble metal nanoparticles.In addition,their performance in catalysis,antibacterial and angiography was also studied.The details are as follow:?2?Firstly,we briefly reviewed the research progress of magnetic Fe₃O₄ core/shell nanocomposites.The synthesis methods and applications of magnetic Fe₃O₄nanoparticles and magnetic Fe₃O₄ core/shell nanocomposites are introduced,and several magnetic Fe₃O₄ core/shell nanocomposites have been listed.?3?The magnetic Fe₃O₄ nanoparticles with good monodispersity were prepared by solvothermalmethod,andtheFe₃O₄@PDA/Au/PDAand Fe₃O₄@PDA/Au/PDA/Au/PDA core/shell nanocomposites were prepared by a layer-by-layermethod.Inaddition,theFe₃O₄@PDA/Au/PDA/Ag/PDAand Fe₃O₄@PDA/Au/PDA/Pd/PDA core/shell nanocomposites containing two noble metal nanoparticles were successfully prepared by changing the noble metal species supported.It was found that these nanocomposites exhibited good catalytic activity in the chemical reaction of degrading the organic pollutant 4-nitrophenol to form the important pharmaceutical intermediate 4-aminophenol.At the same time,due to the presence of the magnetic Fe₃O₄ core,these nanocomposites can be collected from the reaction solution by simple magnetic separation after the reaction.Moreover,due to the protective effect of the PDA shell layer,the precious metal nanoparticles can be effectively prevented from being leached in the reaction,thereby greatly improving the recycling performance of these materials,so that these nanoparticles can still maintain95%catalytic activity after 7 cycles of catalytic reaction.?4?On the basis of the previous work,the synthetic method was improved,and a simpler ultrasonic-assisted one-step coating method was used to load the Au nanoparticles on the Fe₃O₄ core,and the Fe₃O₄@Au/PDA core/shell structure was successfully prepared.The morphology and dispersibility of the nanocomposite are further improved due to fewer synthetic steps.By changing the core material,more core/shell nanocomposites such as?-FeOOH@Au/PDA,SiO₂@Au/PDA,and CNT@Au/PDA were prepared.In addition,the catalytic properties of these materials in the degradation of 4-nitrophenol have also been studied.These nanocomposites also exhibit good catalytic activity and cycle performance.The performance of Fe₃O₄@Au/PDA nanoparticles as MRI contrast agent was also studied.The experimental results showed that the T₂ relaxation rate reaches 101.6 mM^-1S^-1,indicating that it has good contrast ability.?5?Fe₃O₄@PDA/Ag/PDA nanoparticles were prepared by a layer-by-layer method.The PDA shell effectively prevents the Ag nanoparticles from being leached,and also prevents the Ag nanoparticles from agglomerating,allowing the Ag nanoparticles to maintain a small particle size.Therefore,the material exhibits good antibacterial properties and can effectively inhibit the growth of Staphylococcus aureus and Escherichia coli.