Félix Lizbet León, Rodriguez Martínez Marco Antonio, Pacheco Salazar David Gregorio, Huamani Coaquira José Antonio
Laboratorio de Películas Delgadas, Escuela Profesional de Física, Universidad Nacional de San Agustín de Arequipa Av. Independencia s/n Arequipa Peru
Laboratory of Magnetic Characterization, Instituto de Física, Universidade de Brasília DF 70910-900 Brasília Brazil.
RSC Adv. 2020 Nov 17;10(68):41807-41815. doi: 10.1039/d0ra08872b. eCollection 2020 Nov 11.
Magnetic nanoparticles (NPs) are especially interesting for several biomedical applications due to their chemical surface, especially for targeted cancer imaging and therapeutics. In order to realize these applications, it is important to know their magnetic properties among other complementary properties that help to improve the understanding of the synthesis process. In this work, we report the magnetic properties of polyethyleneimine-coated magnetite (PEI-FeO) NPs synthesized by a one-step method the co-precipitation method and using PEI as a stabilizer. Transmission electron microscopy (TEM) images revealed agglomerated magnetic nanoparticles with an average size of ∼10 nm; meanwhile, the X-ray diffraction (DRX) analysis confirmed a pure magnetite phase. The study of magnetic properties shows a superparamagnetic system with coexistence of non-interacting single NPs with a low blocking temperature (∼35 K) and interacting NPs in the aggregates with a higher blocking temperature (>150 K), in which the interparticle interactions of magnetic cores dominate over surface spin disorder. The interaction between the surface spin-disorder layer and NP core was found to be weak, related to a weak exchange bias effect. A maximum specific loss power (SLP) value of 70 W g was obtained ( = 571 kHz and = 23.87 kA m) indicating that the magnetic response plays a crucial role in determining the heating efficiency for future applications.
磁性纳米颗粒（NPs）因其化学表面特性而在多种生物医学应用中备受关注，特别是在靶向癌症成像和治疗方面。为了实现这些应用，了解它们的磁性以及其他有助于更好理解合成过程的互补特性非常重要。在这项工作中，我们报告了通过一步法——共沉淀法并使用聚乙烯亚胺（PEI）作为稳定剂合成的聚乙烯亚胺包覆磁铁矿（PEI-FeO） NPs的磁性。透射电子显微镜（TEM）图像显示团聚的磁性纳米颗粒，平均尺寸约为10 nm；同时，X射线衍射（DRX）分析证实为纯磁铁矿相。磁性特性研究表明，该体系为超顺磁性体系，存在低阻塞温度（约35 K）的非相互作用单个NPs与高阻塞温度（>150 K）的团聚体中相互作用的NPs共存，其中磁芯间的相互作用在表面自旋无序中占主导。发现表面自旋无序层与NP核之间的相互作用较弱，这与弱交换偏置效应有关。获得了70 W g的最大比损耗功率（SLP）值（ = 571 kHz且 = 23.87 kA m），表明磁响应在决定未来应用的加热效率方面起着关键作用。
