Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, C/Mariano Esquillor s/n, CP 50018, Zaragoza, Spain.
Laboratorio de Microscopias Avanzadas (LMA), Universidad de Zaragoza, C/Mariano Esquillor s/n, CP 50018, Zaragoza, Spain.
Sci Rep. 2019 Mar 8;9(1):3992. doi: 10.1038/s41598-019-40341-y.
The Linear Response Theory (LRT) is a widely accepted framework to analyze the power absorption of magnetic nanoparticles for magnetic fluid hyperthermia. Its validity is restricted to low applied fields and/or to highly anisotropic magnetic nanoparticles. Here, we present a systematic experimental analysis and numerical calculations of the specific power absorption for highly anisotropic cobalt ferrite (CoFeO) magnetic nanoparticles with different average sizes and in different viscous media. The predominance of Brownian relaxation as the origin of the magnetic losses in these particles is established, and the changes of the Specific Power Absorption (SPA) with the viscosity of the carrier liquid are consistent with the LRT approximation. The impact of viscosity on SPA is relevant for the design of MNPs to heat the intracellular medium during in vitro and in vivo experiments. The combined numerical and experimental analyses presented here shed light on the underlying mechanisms that make highly anisotropic MNPs unsuitable for magnetic hyperthermia.
线性响应理论（LRT）是一种广泛接受的分析磁性纳米粒子用于磁流体热疗的功率吸收的框架。它的有效性仅限于低应用场和/或高度各向异性的磁性纳米粒子。在这里，我们对具有不同平均尺寸和不同粘性介质的高各向异性钴铁氧体（CoFeO）磁性纳米粒子的比功率吸收进行了系统的实验分析和数值计算。确定了布朗松弛作为这些粒子中磁损耗的起源的主导地位，并且比功率吸收（SPA）随载体液体粘度的变化与 LRT 近似一致。粘度对 SPA 的影响与设计 MNPs 以在体外和体内实验中加热细胞内介质有关。这里呈现的组合数值和实验分析揭示了使高各向异性 MNPs 不适合磁热疗的潜在机制。
