Research On Properties And Applications Of Iron Oxide-based Nanomaterials

Iron oxide nanomaterials,as kind of typical magnetic nanomaterials,have set off a research upsurge in the military,environmental,medical,and other fields due to the dual characteristics of nanomaterials and magnetic materials.However,in practical application,to obtain stable physical and chemical properties,uniform size,good dispersion,and biocompatibility and give them better function,it is necessary to optimize their structure.In this paper,taking iron oxide nanoparticles as the research object,through the design of the iron oxide-based composite nanomaterials,fully analyze material morphology,structure,and surface functional groups,systematically to explore the magnetic separation of materials,electromagnetic shielding,catalytic properties,successfully constructed a high sensitive biological colorimetric sensor,efficient cationic dye adsorbent,efficient and flexible electromagnetic shielding film,and developed a new preparation method of functional hydrogels.The main study contents are as follows:1.Based on magnetic separation and enrichment characteristics of the iron oxide-based magnetic composite nanospheres,a sensor was established for the detection of the Hepatitis B virus marker（HBs Ag）with high sensitivity.Firstly,magnetic composite spheres were prepared by pyrolysis and layer by layer assembly method,and then immunomagnetic spheres（IMNPs）were obtained by combining the composite spheres with antibodies using streptavidin and biotin as bridges.Because streptavidin and biotin molecules have a strong affinity and a single streptavidin can bind to multiple biotins,the obtained IMNPs not only have a strong magnetic ability to achieve simple magnetic separation but also have a high load of antibodies and specific recognition and efficient capture of HBs Ag.Finally,combining IMNPs and the high catalytic activity of horseradish peroxidase to induce colorimetric signal generation,a highly sensitive colorimetric detection of HBs Ag was realized,with a detection limit as low as 0.012ng/m L,far lower than the clinical detection index（0.5 ng/m L）.Moreover,the time of detection was less than 2 h,and it had strong anti-interference and feasibility of actual sample detection.2.Based on the adsorption properties of the iron oxide-based hybrid hydrogel,a magnetic hydrogel adsorbent was developed for selective and high-efficiency adsorption of cationic dyes.First,iron oxide nanoparticles were in-situ prepared in silk fibroin-polyacrylamide hydrogels by co-precipitation method to obtain iron oxide-based hybrid hydrogels（Fe₃O₄@SF-PAAM）using sodium hydroxide as co-precipitation agent and hydrolytic agent.The obtained Fe₃O₄@SF-PAAM had magnetic functions（magnetic saturation induction intensity of 10 emu/g）and high swelling properties（the swelling ratio is as high as 55867%）.In addition,Fe₃O₄@SF-PAAM also had good mechanical properties.It was found that Fe₃O₄@SF-PAAM can selectively adsorb cationic dyes such as methylene blue,but not anionic dyes such as methyl orange.Especially,there was the adsorption ability as high as 2025 mg/g for methylene blue,which almost exceeded all these types of adsorbents.After 5 cycles of adsorption,the efficiency is still not less than90%,which is recyclable.3.Based on the electromagnetic shielding performance of the iron oxide-based composite film,a flexible conductive magnetic composite film was prepared for efficient electromagnetic wave interference shielding.First,the casting and annealing methods were used to build iron oxide-based composite films（MFPs）by mixing iron oxide nanoparticles with titanium carbide nanosheets as conductive magnetic fillers and polyurethane as the flexible substrate.The results show that MFP has good magnetic,high biocompatibility,and high conductivity（439.4-1286.8 S/m）.Secondly,MFP has a tightly stacked layered structure and excellent mechanical properties with a tensile strain of 16.5-30%.Electromagnetic shielding research results show that the MFP has efficient electromagnetic shielding performance（26.11-30.63 d B）,and still maintains effective electromagnetic shielding performance after being bent 5000 times,with reliable stability.4.Based on the catalytic ability of the iron oxide-based mixture,a new preparation method was proposed for the rapid and stable preparation of hydrogel,and the application of a hydrogel-based flexible sensor for real-time monitoring of human movement was explored.First,iron oxide nanoparticles with peroxidase-like catalytic performance were obtained through the solvothermal method,and then iron oxide nanoparticles were combined with titanium carbide nanosheets as conductive filler,crosslinking agent,and catalyst.Subsequently,ammonium persulfate,an initiator,was catalyzed to generate hydroxyl radicals to initiate the rapid polymerization of acrylamide and ultrafast formation of hydrogels at room temperature without additional energy,and the gelation process can be activated in only 7 s.The combination of iron oxide nanoparticles and titanium carbide nanosheets not only makes the gel preparation process simple and fast,but also the obtained hydrogel’s tensile elongation is 803-1660%,and the electrical conductivity is 1.63×10^-2-6.44×10^-2 S/m.The subsequent strain sensing results showed that the hydrogel had a wide range of strain sensing,GF factor was 1.9,3.5,and 6.6 under 0-50%small strain,50-100%,and 100-300%large strain,respectively,and realized the monitoring of changes in human joints and facial expressions with fast response and high sensitivity.