Adjusting the Néel relaxation time of Fe3O4/ZnxCo1-xFe2O4 core/shell nanoparticles for optimal heat generation in magnetic hyperthermia

FABRIS, FERNANDO; LOHR, JAVIER HERNÁN; LIMA, ENIO; DE ALMEIDA, ADRIELE APARECIDA; TROIANI, HORACIO; RODRÍGUEZ, LUIS M.; VÁSQUEZ MANSILLA, MARCELO; AGUIRRE, MYRIAM; GOYA, GERARDO FABIAN; RINALDI, DANIELE; GHIRRI, ALBERTO; PEDDIS, DAVIDE; FIORANI, DINO; ZYSLER, ROBERTO D; DE BIASI, EMILIO; WINKLER, ELIN

NANOTECHNOLOGY

IOP PUBLISHING LTD

Lugar: Londres; Año: 2020 vol. 32 p. 65703 - 65703

0957-4484

In this work it is shown a precise way to optimize the heat generation in high viscosity magnetic colloids, by adjusting the Néel relaxation time in core/shell bimagnetic nanoparticles, for magnetic fluid hyperthermia (MFH) applications. To pursue this goal, Fe3O4/ZnxCo1−xFe2O4 core/shell nanoparticles were synthesized with 8.5 nm mean core diameter, encapsulated in a shell of ∼1.1 nm of thickness, where the Zn atomic ratio (Zn/(Zn+Co) at%) changes from 33 to 68 at%. The magnetic measurements are consistent with a rigid interface coupling between the core and shell phases, where the effective magnetic anisotropy systematically decreases when the Zn concentration increases, without a significant change of the saturation magnetization. Experiments of MFH of 0.1 wt% of these particles dispersed in water, in Dulbecco modified Eagles minimal essential medium, and a high viscosity butter oil, result in a large specific loss power (SLP), up to 150Wg−1, when the experiments are performed at 571 kHz and 200 Oe. The SLP was optimized adjusting the shell composition, showing a maximum for intermediate Zn concentration. This study shows a way to maximize the heat generation in viscous media like cytosol, for those biomedical applications that require smaller particle sizes.