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-Fe3O4) NPs synthesized by a one-step method via 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-1 was obtained (f = 571 kHz and H = 23.87 kA m-1) indicating that the magnetic response plays a crucial role in determining the heating efficiency for future applications.
Bibliographical noteFunding Information:
This work was nancially support by CONCYTEC – FONDECYT within the framework of the call E038-01 [contract no. 07-2019-FONDECYT-BM-INC. INV]. J. A. H. C. thanks to the Brazilian agencies CNPq [grants number 301455/2017-1, 443652/2018-0] and FAPDF [grant number 00193.0000151/2019-20] for the nancial support. The authors would like to thank Dr Gerardo. F. Goya, Dr R. Fernández-Pacheco and Dr A. Ibarra and the Laboratorio de Microscopias Avanzadas for their advices and technical support with the HRTEM analysis, and to the Servi-cios Científco Técnicos CIBA-IACS-UZ for the use of its facilities.
© 2020 The Royal Society of Chemistry.