Monodisperse Iron Oxides Supraparticles’ Aqueous Fabrication:Surface Functionalization And Catalytic Performance

Iron oxides supraparticles possess unique hierarchical structure,diverse surface modification and excellent magnetic properties.Therefore,the exploration of green and eco-friendly fabrication method is of great significance for both assembly mechanism research and biological applications.In this paper,the monodisperse Fe₂O₃ SPs and Fe₃O₄ SPs can be one-step in situ self-assembled in 100%water solution,and then the surface functionalization and catalytic performance are studied.The dissertation mainly includes the following four chapters:The first chapter is the introduction.Firstly,the properties and main applications of magnetic nanomaterials are summarized.Secondly,the definition,self-assembly mechanism and common fabrication of supraparticles are described in detail.Finally,the performance and application progress of various iron oxide supraparticles are reviewed.Based on the current preparation limitation and single application,we propose the designs of this dissertation.In the second chapter,the preparation,self-assembly mechanism,surface modification and photothermal properties of size-tunable Fe₂O₃ SPs are studied.Firstly,by means of urea as p H modulator,monodisperse Fe₂O₃ SPs with 8 nm,25 nm and 47 nm in diameters can be one-step in situ self-assembled in 100%water solution.Then,the SPs can be reliably fabricated by various carboxyl stabilizers,indicating the versatility of the proposed fabrication system.Thirdly,it is found that the dynamic hydrolysis process of urea is the key to nanoparticles’self-assembly.Finally,by means of gallic acid（GA）modification,the corresponding products（denoted as Fe₂O₃@GA SPs）can be endowed near-infrared light-absorbing properties,and exhibit size-dependent photothermal performances and cellular uptake.In terms of 8 nm sized Fe₂O₃@GA SPs,they possess the highest photothermal conversion efficiency（66.63%）and cellular uptake（8.4 pg Fe/cell）.In the third chapter,the eco-friendly fabrication and catalytic performance of monodisperse superparamagnetic Fe₃O₄ SPs are researched.Firstly,by means of optimizing the reaction conditions（using ascorbic acid as reducing agent,citrate as stabilizer,p H 6.0,reaction temperature 180^oC）,well-defined and monodisperse superparamagnetic Fe₃O₄ SPs with 500 nm in diameter are successfully fabricated in100%water solution.Secondly,Fe₃O₄ SPs exhibit excellent peroxidase activity in the acetic acid buffer solution at p H 3.5.After 10 catalytic cycles,the absorbance at 652nm was 55.2%of the initial value.Finally,Fe₃O₄ SPs can realize the detection of glucose.The fourth chapter summarizes the highlight of this work and looks forward to the potential prospects.