Preparation And Properties Of Magnetic Polydopamine Composite Particles

Polydopamine（PDA）is a polymer that can perform surface functionalization on almost all chemical materials.Its unique surface modification function and good biocompatibility make it an excellent shell material.At the same time,in addition to the strong metal ion chelating ability and reducing activity,PDA also has a wealth of surface functional groups（-OH,-NH2）,so it has a wide range of applications in substance mineralization,pharmaceutical biology,nanomaterial functionalization,biosensor,pollutant degradation and so on.In recent years,magnetic polydopamine nanocomposites have attracted people’s attention.Studies have shown that this kind of composites have great potential applications in biomedical fields due to their unique magnetic effects and physical and chemical functions.PDA has good biocompatibility and photothermal effect.The magnetic polydopamine composite particles produced by the combination of PDA and magnetic nanomaterials not only have magnetic targeting effect,but also can kill harmful cells by photothermal effect.It has very important scientific significance in the research and development of new nanomaterials.According to the research results,this master’s thesis,starting from the structural design of the new magnetic polydopamine composite particles,developed high-performance core-shell composite materials,optimized the physical and chemical properties of the materials,and preliminarily explored its application prospects in drug loading,photothermal therapy,biological antibacterial and other fields.The specific structure of this paper is as follows:（1）The research progress on the preparation and properties of magnetic polydopamine composite particles was summarized by investigating the literature.The preparation methods of hollow Fe₃O₄ magnetic nanoparticles（h-Fe₃O₄）,Fe₃O₄@SiO₂magnetic composite particles and core-shell magnetic polydopamine nanocomposites were described.The structure-activity relationship of these materials was analyzed.The application progress of magnetic dopamine composites in catalysis,antibacterial,drug loading,photothermal therapy and other fields was discussed.At the same time,according to the deficiencies of the existing research,the necessity of this master’s thesis research is analyzed.（2）First,the magnetically separable h-Fe₃O₄@Au/PDA hollow structure nanospheres were developed,and their nano catalytic performance and drug loading capacity were studied.The hollow structure of h-Fe₃O₄ was prepared by solvothermal method,and then the hollow structure h-Fe₃O₄@Au/PDA composite particles were prepared by simple one-step redox polymerization.It is found that the material has excellent catalytic effect in the degradation of nitrophenol.The catalytic activity of h-Fe₃O₄@Au/PDA nanospheres can remain 90%after 7 cycles due to the protection of PDA shell.At the same time,h-Fe₃O₄@Au/PDA hollow composite particles have a strong drug loading capacity,the material of ibuprofen loading capacity can reach 12.4%.Based on the above study of h-Fe₃O₄@Au/PDA,porous h-Fe₃O₄@Au/PDA composite particles with more obvious hollow structure were prepared by nitric acid etching method.The photodynamic drug loading capacity,photothermal effect and antibacterial ability of porous h-Fe₃O₄@Au/PDA composite particles were studied.h-Fe₃O₄@Au/PDA porous hollow composite particles have a larger cavity,and the loading capacity of tetracarboxylic zinc phthalocyanine photosensitizer can reach 44 g/mg.Due to the photothermal effect of both Au and polydopamine,h-Fe₃O₄@Au/PDA porous hollow composite particles show excellent photothermal bactericidal performance.The photothermal properties of h-Fe₃O₄@Au/PDA porous hollow composite particles with different corrosion degrees were studied.It was found that the temperature of the sample could rise to 70℃after 10 minutes of laser irradiation.At the same time,h-Fe₃O₄@Au/PDA porous hollow composite particles showed good photothermal antibacterial properties and could effectively inhibit the growth of Escherichia coli.（3）The chain structure Fe₃O₄@SiO₂/Au/PDA composite particles were developed,and the photothermal sterilization performance of the material was studied.Firstly,magnetic Fe₃O₄ nanoscale chain structure was prepared by magnetic-induced solvothermal method,and then the magnetic chain with Fe₃O₄@SiO₂ core-shell structure was formed by coating Fe₃O₄ with SiO₂ by sol-gel method.Then,using in situ redox polymerization reaction between HAu Cl₄ and dopamine,the surface of the above shell was coated with Au/PDA composite shell,so as to develop Fe₃O₄@SiO₂/Au/PDA magnetic composite nanochain.The material also has excellent photothermal properties,which can be further applied in the field of photothermal antimicrobial.It was found that the antimicrobial properties of the material were further enhanced under the action of external magnetic field.