Abstract Ferrous - ferric ions and surface functional groups on iron oxide nanoparticles (NPs) can be tailored to attain requisite magneto-thermal properties propitious for hyperthermia mediated tumor ablation. We report the synthesis of polyvinylpyrrolidone (PVP) grafted octahedron shaped iron oxide NPs via a facile hydrothermal route for magnetic fluid hyperthermia. PVP grafted nano-octahedrons are being first time used for the morphology dependent hyperthermia study. Physico-chemical, magnetic and thermal properties have been systematically characterised in the present study. Aqueous suspension of nano-octahedrons has displayed excellent colloidal stability with a hydrophilic nature. Magnetic nano-octahedrons are found to possess nearly superparamagnetic behaviour with a saturation magnetisation value of ∼ 82 emu/g and very low coercivity of ∼ 138 Oe pertinent for hyperthermia applications. A high specific absorption rate (SAR) value of ∼ 963 W/g under an AC magnetic field of 600 Oe and 316 kHz has been obtained with concentration of 5 mg/mL which is predominantly attributed to hysteresis and effective relaxation losses. In order to elucidate the role of viscosity on Brownian relaxation, a detailed analysis of the amount of heat dissipation from nano-octahedrons in different aqueous media such as water, ethylene glycol (EG) and agar solution have also been investigated. Viscosity of these ferrofluids has been observed to be strongly dependent on the Brownian relaxation consequently changing the SAR values. Moreover, nano-octahedrons are biocompatible and exhibit non-hemolytic activity.

中文翻译：

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用于磁流体热疗的氧化铁纳米八面体的感应量热评估

摘要 氧化铁纳米颗粒 (NPs) 上的亚铁 - 三价铁离子和表面官能团可以定制以获得有利于热疗介导的肿瘤消融所需的磁热特性。我们报告了聚乙烯吡咯烷酮（PVP）接枝八面体形氧化铁纳米颗粒的合成，通过一种简便的水热途径用于磁流体热疗。PVP 接枝的纳米八面体首次用于形态相关的热疗研究。本研究已经系统地表征了物理化学、磁学和热学性质。纳米八面体的水悬浮液表现出优异的胶体稳定性和亲水性。发现磁性纳米八面体具有近乎超顺磁性的行为，饱和磁化强度值为 82 emu/g，矫顽力非常低，约为 138 Oe，适用于热疗应用。在 600 Oe 和 316 kHz 的交流磁场下，已获得约 963 W/g 的高比吸收率 (SAR) 值，浓度为 5 mg/mL，这主要归因于滞后和有效弛豫损失。为了阐明粘度对布朗弛豫的作用，还研究了纳米八面体在不同水性介质（如水、乙二醇 (EG) 和琼脂溶液）中的散热量的详细分析。已经观察到这些铁磁流体的粘度强烈依赖于布朗弛豫，从而改变了 SAR 值。而且，