title: Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe₃O₄ nanoparticles for biomedical applications.
abstract: In this work, the effect of nanoparticle confinement on the magnetic relaxation of iron oxide (Fe3O4) nanoparticles (NP) was investigated by measuring the hyperthermia heating behavior in high frequency alternating magnetic field. Three different Fe3O4 nanoparticle systems having distinct nanoparticle configurations were studied in terms of magnetic hyperthermia heating rate and DC magnetization. All magnetic nanoparticle (MNP) systems were constructed using equivalent ~10nm diameter NP that were structured differently in terms of configuration, physical confinement, and interparticle spacing. The spatial confinement was achieved by embedding the Fe3O4 nanoparticles in the matrices of the polystyrene spheres of 100 nm, while the unconfined was the free Fe3O4 nanoparticles well-dispersed in the liquid via PAA surface coating. Assuming the identical core MNPs in each system, the heating behavior was analyzed in terms of particle freedom (or confinement), interparticle spacing, and magnetic coupling (or dipole-dipole interaction). DC magnetization data were correlated to the heating behavior with different material properties. Analysis of DC magnetization measurements showed deviation from classical Langevin behavior near saturation due to dipole interaction modification of the MNPs resulting in a high magnetic anisotropy. It was found that the Specific Absorption Rate (SAR) of the unconfined nanoparticle systems were significantly higher than those of confined (the MNPs embedded in the polystyrene matrix). This increase of SAR was found to be attributable to high Néel relaxation rate and hysteresis loss of the unconfined MNPs. It was also found that the dipole-dipole interactions can significantly reduce the global magnetic response of the MNPs and thereby decrease the SAR of the nanoparticle systems.
authors: Department of Physics, University of Cincinnati, Cincinnati, OH 45221, USA.
authors: M E
authors: ME
authors: Sadat
authors: The Materials Science and Engineering Program, Department of Mechanical and Materials Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221, USA.
authors: Ronak
authors: R
authors: Patel
authors: Department of Neuroscience, University of Cincinnati, OH 45221, USA.
authors: Jason
authors: J
authors: Sookoor
authors: Ames Laboratory, Iowa State University, Ames, IA 50011, USA; Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA.
authors: Sergey L
authors: SL
authors: Bud'ko
authors: Department of Geological & Environmental Sciences, Stanford University, Stanford, CA 94305-2115, USA.
authors: Rodney C
authors: RC
authors: Ewing
authors: Department of Geological & Environmental Sciences, Stanford University, Stanford, CA 94305-2115, USA.
authors: Jiaming
authors: J
authors: Zhang
authors: Med-X Institute, Shanghai Jiao Tong University, Shanghai 200030, PR China.
authors: Hong
authors: H
authors: Xu
authors: Shanghai East Hospital, The Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200120, China.
authors: Yilong
authors: Y
authors: Wang
authors: James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH 45267, USA.
authors: Giovanni M
authors: GM
authors: Pauletti
authors: Department of Physics, University of Cincinnati, Cincinnati, OH 45221, USA.
authors: David B
authors: DB
authors: Mast
authors: The Materials Science and Engineering Program, Department of Mechanical and Materials Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221, USA; Med-X Institute, Shanghai Jiao Tong University, Shanghai 200030, PR China; Shanghai East Hospital, The Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai 200120, China. Electronic address: donglu.shi@uc.edu.
authors: Donglu
authors: D
authors: Shi
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D016880:Anisotropy; D006358:Hot Temperature; D060526:Magnetic Fields; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008422:Materials Testing; D011137:Polystyrenes / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D000180:Acrylic Resins; D058185:Magnetite Nanoparticles; D011137:Polystyrenes; C006903:carbopol 940
keywords: Dipole interaction; Fe(3)O(4) nanoparticles; Magnetic anisotropy; Néel relaxation; Superparamagnetism