Effect of Particle Size of Magnetite Nanoparticles on Heat Generating Ability under Alternating Magnetic Field

Abstract

In this study, magnetite nanoparticles (MNPs) with series of size varying from 8 nm to 103 nm were synthesized by a chemical co-precipitation and an oxidationprecipitation method to aim for finding the optimum particle size which has high heating efficiency in the applied magnetic field (9.6–23.9 kA·m–1, 100 kHz). Their in vitro heating efficiencies in agar phantom, at a MNPs concentration of 58 mg Fe·ml–1, were measured in the applied field. The temperature increase (ΔT) of the agar phantom at 30 s was 9.3 °C for MNPs of 8 nm, exhibiting a high heating efficiency in a field intensity of 9.6 kA·m–1. The ΔT of agar was 55 °C for MNPs of 24 nm and 25 °C for MNPs of 8 nm in a field intensity of 23.9 kA·m–1. The excellent heating efficiency for MNPs of 24 nm might be a combined effect of relaxation loss and hysteresis loss of the magnetic particles.