Adaptive iron-based magnetic nanomaterials of high performance for biomedical applications

With unique physicochemical properties and biological effects,magnetic nanomaterials(MNMs)play a crucial role in the biomedical field.In particular,magnetic iron oxide nanoparticles(MIONPs)are approved by the United States Food and Drug Administration(FDA)for clinical applications at present due to their low toxicity,biocompatibility,and biodegradability.Despite the unarguable effectiveness,massive space for improving such materials'performance still needs to be filled.Recently,many efforts have been devoted to improving the preparation methods based on the materials'biosafety.Besides,researchers have successfully.regulated the performance of magnetic nanoparticles(MNPs)by changing their sizes,morphologies,compositions;or by.aggregating as-synthesized MNPs in an orderly arrangement to meet various clinical requirements.The rise of cloud computing and artificial intelligence techniques provides novel ways for fast material characterization,automated data analysis,and mechanism demonstration.In this review,we summarized the studies that focused on the preparation routes and performance regulations of high-quality MNPs,and their special properties applied in biomedical detection,diagnosis,and treatment.At the same time,the future.development of MNMs was also discussed.

Self-assembled magnetic nanomaterials:Versatile theranostics nanoplatforms for cancer

Self-assembled magnetic nanomaterials(MNMs)are a class of promising biomaterials possessing excellent physiochemical and biological characteristics,making them highly attractive in biomedical applications.A myriad of magnetic nanosystems can be created by using self-assembly as a synthetic tool.Favorable nano-bio interfacial properties are shown in these promising self-assembled magnetic nanosystems,while still retaining their physical/chemical functionalities.This review aims to provide a systematical overview of the self-assembled MNMs.In addition,this review highlights their implementations in cancer theranostics in detail.Overall,this review points out the direction for the application of self-assembled MNMs in biomedicine,and presents how clinical oncology could benefit from the self-assembled nanotechnology.

Greatly Enhanced Methanol Oxidation Reaction of CoPt Truncated Octahedral Nanoparticles by External Magnetic Fields

Tunable behavior in electrocatalysis by external multifields,such as magnetic field,thermal field,and electric field,is the most promising strategy to expand the theory,design,and synthesis of state-of-the-art catalysts and the cell in the near future.Here,a systematic investigation for the effect of external magnetic field and thermal field on methanol oxidation reactions(MOR)in magnetic nanoparticles is reported.For Co_(42)Pt_(58)truncated octahedral nanoparticles(TONPs),the catalytic performance in MOR is greatly increased to the maximum of 14.1%by applying a magnetic field up to 3000 Oe,and it shows a monotonical increase with increasing working temperature.The magnetic enhanced effect is closely related to the Co content of Co_(x)Pt_(100-x)TONPs.Furthermore,the enhancement effect under a magnetic field is more obvious for Co_(42)Pt_(58)TONPs annealed at 650℃.First-principle calculation points out that the magnetic fields can facilitate the dehydrogenation of both methanol and water by suppression of entropy of the electron spin and lowering of the activation barrier,where OH_(ad)intermediates on Co sites play a more important role.The application of magnetic fields together with thermal fields in MOR provides a new prospect to manipulate the performance of direct methanol fuel cells,which will accelerate their potential applications.

Hydrothermal Synthesis and Characterization of PEG-Mn_3O_4 Nanocomposite

Here, we report on the synthesis of PEG-Mn_3O_4 nanocomposite(NP's) via a hydrothermal route by using Mn(acac)2, ethanol, NH3 and PEG-400. The crystalline phase was identified as Mn_3O_4. The crystallite size of the PEG-Mn_3O_4 nanocomposite was calculated as 12±5 nm from X-ray line profile fitting and the average particle size from TEM was obtained as 200 nm. This reveals polycrystalline character of Mn_3O_4 NP's. The interaction between PEG-400 and the Mn_3O_4 NP's was investigated by FTIR. Temperature independent AC conductivity of PEG-Mn_3O_4 nanocomposite beyond 20 k Hz provides a strong evidence of ionic conduction through the structure. The conductivity and permittivity measurements strongly depend on the secondary thermal transition of nanocomposite beyond 100. Above that temperature, Mn_3O_4 particles may interact with each other yielding a percolated path that will facilitate the conduction. On the other hand, the relatively lower activation energy(Ea=0.172 e V) for relaxation process suggests that polymer segmental motions of PEG and electrons hopping between Mn2+and Mn3+may be coupled in the sample below 100. Room temperature magnetization curve of the sample does not reach to a saturation, which indicates the superparamagnetic character of the particles. As the temperature increases, the frequency at which(ε′′) reaches a maximum shifted towards higher frequencies. The maximum peak was observed at 1.4 k Hz for 20 while the maximum was detected at 23.2 k Hz for 90.

Osteogenesis effects of magnetic nanoparticles modified-porous scaffolds for the reconstruction of bone defect after bone tumor resection

The treatment of bone defect after bone tumor resection is a great challenge for orthopedic surgeons.It should consider that not only to inhibit tumor growth and recurrence,but also to repair the defect and preserve the limb function.Hence,it is necessary to find an ideal functional biomaterial that can repair bone defects and inactivate tumor.Magnetic nanoparticles(MNPs)have its unique advantages to achieve targeted hyperthermia to avoid damage to surrounding normal tissues and promote osteoblastic activity and bone formation.Based on the previous stage,we successfully prepared hydroxyapatite(HAP)composite poly(lactic-co-glycolic acid)(PLGA)scaffolds and verified its good osteogenic properties,in this study,we produced an HAP composite PLGA scaffolds modified with MNPs.The composite scaffold showed appropriate porosity and mechanical characteristics,while MNPs possessed excellent magnetic and thermal properties.The cytological assay indicated that the MNPs have antitumor ability and the composite scaffold possessed good biocompatibility.In vivo bone defect repair experiment revealed that the composite scaffold had good osteogenic capacity.Hence,we could demonstrate that the composite scaffolds have a good effect in bone repair,which could provide a potential approach for repairing bone defect after bone tumor excision.

Mixed-solvent thermal synthesis and magnetic properties of flower-like microstructured nickel

Flower-like microstructured nickel was synthesized by a facile mixed-solvent thermal process. The structure, morphology, and magnetic properties of the reaction products were investigated, respectively, by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and vibrating sample magnetometry （VSM）. The results showed that the products consisted of a face-centered cubic （fcc） structure with lattice constant of u=3.524A. The average diameter of flower-like microstructured nickel was about 5 um and the thickness of a single flake was about 100nm. Magnetic measurement showed that these powders exhibited ferromagnetic characteristics.