Low-temperature magnetic properties of horse spleen ferritin  

作　　者：TIAN LanXiang 1,2,CAO ChangQian 1,2,LIU QingSong 1,2 &PAN YongXin 1,2 1Key Laboratory of the Earth’s Deep Interior,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China 2Franco-Chinese Biomineralization and Nano-structures Laboratory,Beijing 100029,China 

出　　处：《Chinese Science Bulletin》2010年第27期3174-3180,共7页

基　　金：supported by the National Natural Science Foundation of China(40821091 and 40904017);the CAS/SAFEA International Partnership Program for Creative Research Teams(KZCXZ-YW-T10)

摘　　要：The magnetic properties of the antiferromagnetic cores in ferritin are of importance in the construction and improvement of ferritin-based magnetic resonance imaging systems and their application to environmental magnetism.In this study,we carry out integrated magnetic and transmission electron microscopy analyses of horse spleen ferritin(HoSF)to understand the relationships between the magnetic behavior of HoSF and temperature,applied field and grain-size distributions.The R-value from the Wohlfarth-Cisowski test for the investigated sample at 5 K was 0.46,indicating very weak magnetostatic interactions among the nanoparticles of HoSF.The nanoparticles of HoSF show superparamagnetic properties at room temperature,while below the blocking temperature of Tb≈12 K it has a net magnetic moment that comes from the uncompensated spins of the nanoparticle surface or spin-canting.The thermal relaxation process of HoSF follows the Néel-Arrhenius expression.From low-temperature AC susceptibility data,we calculated the effective magnetic anisotropy energy Ea=(5.52±0.16)×10-21 J;the effective magnetic anisotropy energy constant Keff=(4.65±0.14)×10 4 J/m3 and the pre-exponential frequency factor f0 =(4.52±2.93)×1011 Hz.These values are useful in understanding the magnetic behavior of the antiferromagnetic nanoparticles and their potential application in biomedical technology.The magnetic properties of the antiferromagnetic cores in ferritin are of importance in the construction and improvement of fer- ritin-based magnetic resonance imaging systems and their application to environmental magnetism. In this study, we carry out integrated magnetic and transmission electron microscopy analyses of horse spleen ferritin （HoSF） to understand the relationships between the magnetic behavior of HoSF and temperature, applied field and grain-size distributions. The R-value from the Wohlfarth-Cisowski test for the investigated sample at 5 K was 0.46, indicating very weak magnetostatic interactions among the nanoparticles of HoSF. The nanoparticles of HoSF show superparamagnetic properties at room temperature, while below the blocking temperature of Tb ≈ 12 K it has a net magnetic moment that comes from the uncompensated spins of the nanoparticle surface or spin-canting. The thermal relaxation process of HoSF follows the Neel-Arrhenius expression. From low-temperature AC susceptibility data, we calculated the effective magnetic anisotropy energy Ea=（5.52±0.16）×10-21 J; the effective magnetic anisotropy energy constant Keff =（4.65±0.14）×10 4 J/m3 and the pre-exponential frequency factor f0=（4.52±2.93）×10 11 Hz. These values are useful in understanding the magnetic behavior of the antiferromagnetic nanoparticles and their potential application in biomedical technology.

关 键 词：马脾铁蛋白 低温度 磁性质 透射电子显微镜 磁各向异性常数 纳米粒子 生物医学技术 交流磁化率 

分 类 号：O482.5[理学—固体物理] Q513[理学—物理]