Malignant tumors occur by uncontrolled multiplication of the body's cells. Currently, a promising technique, called magnetic hyperthermia, has been intensively researched. The technique makes it possible to interrupt the growth of tumor cells by the localized application of heat from the magnetization/demagnetization of magnetic nanoparticles (the Joule effect). The amount of heat generated depends on the magnetic material and the characteristics of the external magnetic field. In this work, magnetite Fe3O4 particles (core–shell layer type) were synthesized by the wet coprecipitation method and coated with a polymer blend of polyethylene glycol and polyvinylpyrrolidone (PEG/PVP). The nanoparticles were subjected to a magnetic field of intensity equal to 12 kA m−1 and frequency 202 kHz. Under these conditions, specific absorption rate (SAR) values between 15–48 W g−1 were obtained. The heating curves obtained were adjusted with a proposed mathematical model. The adjustments were satisfactory and showed a good correlation coefficient (at an averaged level of 0.99). In addition, hysteresis curves and FTIR spectra were obtained.

中文翻译：

---

磁铁矿纳米颗粒产生的加热曲线研究在磁热疗中的应用

恶性肿瘤是由于身体细胞不受控制的增殖而发生的。目前，已经深入研究了一种称为磁热疗的有前途的技术。该技术可以通过局部加热磁性纳米粒子的磁化/退磁（焦耳效应）来中断肿瘤细胞的生长。产生的热量取决于磁性材料和外部磁场的特性。在这项工作中，磁铁矿 Fe3O4 颗粒（核壳层型）通过湿法共沉淀法合成，并涂有聚乙二醇和聚乙烯吡咯烷酮（PEG/PVP）的聚合物混合物。纳米粒子受到强度等于 12 kA m-1 和频率 202 kHz 的磁场。在这些条件下，获得了 15-48 W g-1 之间的比吸收率 (SAR) 值。获得的加热曲线用提出的数学模型进行调整。调整结果令人满意，并显示出良好的相关系数（平均水平为 0.99）。此外，还获得了滞后曲线和 FTIR 光谱。