The Preparation Of Ferrimagnetic Assemblies And Its Application Via Magnetic Heating

Magnetic induction heating(magnetothermal)of magnetic nanomaterials is the local hyperthermia effect after the exposure to an alternating magnetic field.By this noninvasive and depth limitless magnetothermal effect,magnetic nanomaterials exhibit great potential in a series of areas including tumor therapy,tissue cryopreservation,nerve control,energy catalysis,self-healing and behavior control.Notably,assembling magnetic nanomaterials with other functional nanomaterials could result in a large number of multifunctional products.However,the poor heating conversion efficiency of these magnetic assembles under an alternating magnetic field leads to the demand of a high content of magnetic nanomaterials in these composites.Focusing on this challenge,we assembled the high-performance ferrimagnetic cube-like iron oxide nanoparticles(CIONs)into a series of magnetic nanoassemblies with excellent ferrimagnetic properties,including ferrimagnetic micelles,ferrimagnetic sponges and ferrimagnetic elastomers.Furthermore,the magnetothermal effects of these magnetic nanoassemblies had been investigated and optimized.(1)With the using of an amphiphilic block copolymer(PHEP-b-PEG),we prepared the emodin-loaded ferrimagnetic micelle(EMM)with several CIONs in the flowable hydrophobic cores.EMM was uniformly dispersed in water,and its hydrodynamic diameter was about 100 nm with good stability.The saturation magnetization of EMM was 116 emu/g,which is twice of that of the commercial contrast agent(Resovist),and its r2 relaxation rate was as high as 271 m M-1s-1.After the exposure to an alternating magnetic field,EMM showed excellent magnetothermal effect.The heating conversion efficiency(specific absorption rate(SAR)value was 2518 W/g,intrinsic loss power(ILP)value was 6.5n Hm2/kg)was much higher than the magnetic nanomaterials used in clinic.In response to the magnetothermal stimuli,the loaded emodin was released rapidly from the flowable core of EMM,and the release rate was much higher than that of the traditional poly(D,L-lactide)(PLA)micelle with a rigid core.Under the guidance of an external magnetic field,EMM was effectively accumulated at the tumor site,improving the uptake efficiency by tumor cells;and then in synergy with the response to an alternating magnetic field,EMM could kill tumor cells at a low dosage,achieving the synergistic anti-tumor effect of chemotherapy and magnetic hyperthermia.(2)With the using of commercial sponges as the template,a series of superhydrophobic ferrimagnetic sponges(FMS)were prepared by a facile dip-coating method.Owing to the excellent dispersity in dip coating solution,the CIONs were uniformly coated on the skeleton surface of the commercial of sponges.On the basis of the large-scale synthesis of CIONs,a large FMS with the volume of 0.6 L was successfully obtained.FMS showed the superior ferromagnetism,with the saturation magnetization as high as 168 emu/g,leading to the rapid magnetic response.The excellent magnetothermal effect of FMS under an alternating magnetic field was obviously higher than the magnetic sponge prepared by traditional spherical iron oxide nanoparticles.Furthermore,the non-contact heating performances of the magnetically heated FMS and the solar heated polydopamine(PDA)-coated sponge with the same size were investigated and compared.When the surface temperature reached ?105 °C,the central temperature of the FMS was increased 140 °C,while the internal temperature of the PDA-coated sponge sharply decreased.This obvious difference in the thermal distribution revealed the advantages of magnetic heating in the three-dimensional aerogels.(3)With the using of the polydimethylsiloxane based polyurea(PDMS-PUa)as the template and the CIONs as the magnetic building block,a series of ferrimagnetic PDMSPUa elastomers were prepared by the solution-mixing mold forming method.Under an alternating magnetic field,the ferrimagnetic elastomer exhibit excellent magnetothermal performance,which could increase both the surface and internal temperatures in a short period.After exposed to an alternating magnetic field,the damaged ferrimagnetic elastomer with the volume of 1*1*1 cm3 had been healed completely during 30 minutes by the magnetic hyperthermia.In comparison,the preparing graphene elastomer with excellent photothermal effect only realized the healing of the surficial damage.Moreover,the mechanical properties of PDMS-PUa elastomers could be enhanced,which was attributed to the uniform distribution of CIONs in these elastomers.These results indicated this non-contact and depth limitless magnetothermal effect could effective heal the damaged elastomers,leading to the potential application in the long-term use of elastomer based flexible devices.