Lasheras Xabier, Insausti Maite, de la Fuente Jesús Martínez, Gil de Muro Izaskun, Castellanos-Rubio Idoia, Marcano Lourdes, Fernández-Gubieda Maria Luisa, Serrano Aida, Martín-Rodríguez Rosa, Garaio Eneko, García Jose Angel, Lezama Luis
BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940 Leioa, Spain.
Instituto de Ciencia de Materiales de Aragón, CSIC/Universidad de Zaragoza & CIBER-BBN, C/ Pedro Cerbuna 12, 50009 Zaragoza, Spain.
Dalton Trans. 2019 Aug 14;48(30):11480-11491. doi: 10.1039/c9dt01620a. Epub 2019 Jul 10.
Manganese/iron ferrite nanoparticles with different Mn doping grades have been prepared by a thermal decomposition optimized approach so as to ascertain the doping effect on magnetic properties and, especially, on the magnetic hyperthermia response. The oxidation state and interstitial position of Mn in the spinel structure is found to be critical. The particle size effect has also been studied by growing one of the prepared samples (from 10 to 15 nm in diameter) by a seed mediated growth mechanism. After analyzing the main structural and chemical parameters such as the Mn/Fe rate, crystalline structure, particle diameter, shape and organic coating, some Mn doping induced changes have been observed, such as the insertion of Mn cations yielded more anisotropic shapes. Magnetic characterization, carried out by DC magnetometry (M(H), M(T)) and electron magnetic resonance (EMR) techniques, has shown interesting differences between samples with varying compositions. Lower Mn doping levels lead to larger saturation magnetization values, while an increase of the Mn content causes the decrease of the effective magnetic anisotropy constant at low T. The homogeneous magnetic response under applied magnetic fields, together with the great effect of nanoparticle size and shape in such a response, has been confirmed by the EMR analysis. Finally, a detailed magnetic hyperthermia analysis has demonstrated the large influence of NP size and shape on the magnetic hyperthermia response. The optimized MnFeO_G sample with a diameter of 15 nm and slightly truncated octahedral shape is presented as an interesting candidate for future magnetic hyperthermia mediated biomedical treatments.
通过热分解优化方法制备了具有不同锰掺杂等级的锰铁氧体纳米颗粒，以确定掺杂对磁性能的影响，特别是对磁热疗响应的影响。发现尖晶石结构中锰的氧化态和间隙位置至关重要。还通过种子介导生长机制使制备的样品之一（直径从10到15纳米）生长，研究了粒径效应。在分析了诸如锰/铁比率、晶体结构、粒径、形状和有机涂层等主要结构和化学参数后，观察到一些锰掺杂引起的变化，例如锰阳离子插入产生了更具各向异性的形状。通过直流磁强计（M(H)，M(T)）和电子磁共振（EMR）技术进行的磁性表征表明，不同组成的样品之间存在有趣的差异。较低的锰掺杂水平导致较大的饱和磁化强度值，而锰含量的增加会导致低温下有效磁各向异性常数的降低。EMR分析证实了外加磁场下的均匀磁响应，以及纳米颗粒尺寸和形状对这种响应的巨大影响。最后，详细的磁热疗分析表明，纳米颗粒尺寸和形状对磁热疗响应有很大影响。直径为15纳米且形状为略截顶八面体形状的优化锰铁氧体（MnFeO_G）样品被认为是未来磁热疗介导生物医学治疗的一个有吸引力的候选材料。
