Properties of nanoparticles prepared from NdFeB-based compound for magnetic hyperthermia application

Abstract

Nanoparticles were prepared from a NdFeB-based alloy using the hydrogen decrepitation process together with high-energy ball milling and tested as heating agent for magnetic hyperthermia. In the milling time range evaluated (up to 10 h), the magnetic moment per mass at H = 1.59 MA m−1 is superior than 70 A m2 kg−1; however, the intrinsic coercivity might be inferior than 20 kA m−1. The material presents both ferromagnetic and superparamagnetic particles constituted by a mixture of phases due to the incomplete disproportionation reaction of Nd2Fe14BHx during milling. Solutions prepared with deionized water and magnetic particles exposed to an AC magnetic field (Hmax ∼ 3.7 kA m−1 and f = 228 kHz) exhibited 26 K ≤ ΔTmax ≤ 44 K with a maximum estimated specific absorption rate (SAR) of 225 W kg−1. For the pure magnetic material milled for the longest period of time (10 h), the SAR was estimated as ∼2500 W kg−1. In vitro tests indicated that the powders have acceptable cytotoxicity over a wide range of concentration (0.1–100 µg ml−1) due to the coating applied during milling.