Nanoscale Thermal Effect And The Theranostic Performance For Ferrimagnetic Vortex-Domain Iron Oxide Nanorings

Magnetic nanomaterials can be used as intelligent materials to mediate the megnetic field.The application of magnetothermal effect in the tumor magnetic heat treatment,targeted drug delivery,deep brain nerve regulation and frozen organ recovery have been gained great progress.This method broke the traditional method in the limitations of these applications,provides a new things and new method for solving such scientific problems.However,the understanding of magnetothermal effect at nanometer scale is not profound.In this paper,By skillfully design,the relationship between the nanothermal and magnetic field intensity and the distance between the surface of the magnetic nanomaterials can be quantitatively measured by using florescence intensity,the nana-thermal of the ferrimagnetic vortex-domain iron oxide nanorings and superparamagnetic iron oxide nanoparticles are compared.After that,FVIOs@Ag₂Se Janus nanomatermials was prepared by using ferrimagnetic vortex-domain iron oxide nanorings?FVIOs?with excellent magnetic properties and silver selenide near-infrared quantum dot?Ag₂Se?,providing material basis for the visualization treatment of tumors.The main research contents of this paper are as follows:?1?Preparation and characterization of Fe₃O₄ magnetic nanomaterials.The ferrimagnetic vortex-domain iron oxide nanorings?FVIOs?and superparamagnetic iron oxide nanoparticles?SPIOs?magnetic nanomaterials were synthesized via hydrothermal and high-temperature solution phase reaction and the amine-PEG spacers of different molecular weights?M_w=1000,2000,5000?functionalized magnetic nanoring by ligand exchange.Further,carboxyl and amino groups were activated by EDC/NHS,and thermosensitive molecules?AZO?and fluorescent molecules?FA?were modified by chemical bond coupling to form FVIOs-PEG-AZO-FA/SPIOs-PEG-AZO-FA.TEM images shows that the size of nanorings were about 53nm with a narrow distribution,the size of nanoparticles were about 20 nm.The power X-ray diffraction patterns of as-prepared nanomaterials demonstrated high crystallinity.VSM results showed FVIOs were vortex-domain and the SPIOs were superparamagnetic and saturation magnetization of two nanomaterials were high.DLS results showed that FVIOs and SPIOs had good dispersion in aqueous solution and could keep stable within 12 days.UV and FL results showed that the surface of magnetic nanomaterials were successfully modified with AZO and FA.?2?Nanothermal effect properties of Fe₃O₄ magnetic nanomaterials.The functionalized IONPs bearing FA connected through thermolabile molecule?AZO?to the tails of PEG spacers of different molecular weights.Under an alternating magnetic field results in increased cleavage of the AZO group and release of the dye from the particles.The released FA was separated from the nanoparticles by magnetic separation,and the dye release was monitored by photoluminescence,thus allowing subnanometer spatial resolution of the temperature measurement.the experiment result shows that:nanothermal T_effff plotted as a function of field amplitude reveals linearly increasing values for all M_w?PEG?;T_eff is plotted versus the distance to the surface of the azo-FA end group?R_G?,showing steep exponential decays of T_eff with increasing distance from the surface for all applied magnetic field amplitudes.For these IONPs,significant local temperature differences can be found in the range from 0 to 3 nm;the nanothermal of FVIOs(T_{eff d=0}=60.3?)is higher than SPIOs(T_{eff d=0}=49.5?).?3?Preparation and magnetotheranostic properties of FVIOs@Ag₂Se nanocomposites.The hydrophobic Ag₂Se quantum dots and FVIOs were prepared by thermal injection and hydrothermal respectively.Then The silver selenide was modified to aqueous phase by microemulsion method.At the same time,the amino group exposed on the surface could be further functionalized.Carboxyl functionalized iron oxide nanorings in aqueous phase were prepared by DHCA ligand exchange method.Finally,carboxyl and amino groups were activated by EDC/NHS,and FVIOs@Ag₂Se nanocomposite was prepared by chemical bond coupling method.Finally,the imaging properties,magnetic thermal properties and photothermal properties of the composites were studied.The results show that the composite have high T₂relaxation rate and high fluorescence intensity,and can be used for MRI/FL dual-mode imaging.When exposed to?367kHz,20 A?alternating current field,the nanocomposite solution at 200?g/mL showed about 33oC increase in temperature within 10 min.The results shows that nanocomposite have an excellent magnetothermal conversion efficiency.When under 808 nm laser?0.8 W/cm²?at 200?g/mL showed about 18oC increase in temperature within 10 min.the composite material can be used as a good photothermal agent.Therefore,The nanocomposite nanomaterials were prepared for diagnosis and treatment,providing an important material basis for the treatment of diseases.