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

Año: 2020

0957-4484

In this work it is shown a precise way to optimize the heat generation in high viscositymagnetic colloids, by adjusting the Néel relaxation time in core/shell bimagneticnanoparticles, for Magnetic Fluid Hyperthermia applications. To pursue this goal,Fe3O4/ZnxCo1-xFe2O4 core/shell nanoparticles were synthesized with 8.5 nm mean corediameter, encapsulated in a shell of 1.1 nm of thickness, where the Zn atomic ratio(Zn/(Zn+Co) at%) changes from 33 at% to 68 at%. The magnetic measurements areconsistent with a rigid interface coupling between the core and shell phases, where theeffective magnetic anisotropy systematically decreases when the Zn concentrationincreases, without a significant change of the saturation magnetization. Experiments ofmagnetic fluid hyperthermia of 0.1 wt% of these particles dispersed in water, Dulbeccomodified Eagles minimal essential medium and a high viscosity butter oil, result in a largespecific loss power (SLP), up to 150 W/g, when the experiments are performed at 571 kHzand 200 Oe. The SLP was optimized adjusting the shell composition, showing a maximumfor intermediate Zn concentration. This study shows a way to maximize the heat generationin viscous media like cytosol, for those biomedical applications that requiere smallerparticle sizes