Role of particle-intrinsic parameters, experimental conditions and interactions in magnetic fluid hyperthermia.

ROBERTO D. ZYSLER; DANIELA P. VALDÉS; GERARDO F. GOYA; ENIO LIMA JR.; EMILIO DE BIASI

Roma

Conferencia; 3NANO-22 Nano Science/Technology/Biotechnology; 2022

3NANO-22 Nano Science

Many works have provided a deeper insight into the power absorption of single—domain magneticnanoparticles (MNP) in magnetic fluid hyperthermia (MFH), both through experimental andtheoretical approaches. However, the role of all parameters relevant to the magnetic relaxationremains a matter of debate. Particularly, there are contrasting results on the effect of interactionsfor elongated arrangements, reporting beneficial [l] and detrimental [2] effects on the specific powerabsorption (SPA).Through the simulation of MNP systems with different particle—intrinsic parameters (size, anisotropy)and experimental conditions (frequency, interactions), we determined four regions (l-IV) of magneticbehavior as a function of relative anisotropy (anisotropy field with respect to the amplitude of the acfield), that dictate the SPA in MFH experiments [3].The limits between regions change with all of these parameters. We analyzed elongated MNParrangements and found out that, for the low relative anisotropy range, dipolar interactions increasethe SPA while they are detrimental for the range of high relative anisotropy. This resolves seeminglycontradictory results of interaction effects in this kind of aggregates reported in the literature. Weexplained the mechanism involved in the enhancement of the SPA by dipolar interactions at the lowanisotropy regime, which is related to an increase in coercivity caused by the shift between the localand the applied magnetic field [4].We also provided a simple, analytical tool aimed at the design of MNPs and the choice of theexperimental conditions for optimal heating. Through the thermal interpretation of its validity range,we conclude that systems with low-thermal-fluctuation influence are the best candidates for MFHdue to their high SPA values.[1] B. Mehdaoui et al. Phys. Rev. B 87 (2013) 174419[2] LC. Branquinho et al. Sci. Rep. 3 (2013) 2887[3] DP. Valdés et al., Phys. Rev. Applied 15 (2021) 044005[4] DP. Valdés et al., Phys. Rev. Applied 14 (2020) 014023