Ultrasmall Fe₃O₄@Au Composite Nanoparticles with Different Sizes of Fe₃O₄ for Magnetic Hyperthermia

Abstract

We reported the synthesis and characterization of ultrasmall iron oxide/gold composite nanoparticles (Fe 3 O 4 @Au NPs) with different sizes of Fe 3 O 4 , and the evaluation of their heating efficiency for potential use in magnetic hyperthermia application. The Fe 3 O 4 NPs were synthesized using the thermal decomposition method with three types of sizes of ~5 nm, ~10 nm, and ~13 nm. Gold was then deposited onto the surface of Fe 3 O 4 NPs by reducing gold acetate at 190°C. The synthesized Fe 3 O 4 and their Fe 3 O 4 @Au NPs were characterized using TEM, EDX, XRD, and VSM analyses. The magnetization of Fe 3 O 4 NPs increased with increasing their size with 74.7 emu/g for ~13 nm. The mass percentage of Au in Fe 3 O 4 @Au NPs estimated from the magnetization values were 94.3, 96.3, 77.0wt% for Fe 3 O 4 ~5 nm@Au, Fe 3 O 4 ~10 nm@Au, Fe 3 O 4 ~13 nm@Au, respectively. The specific absorption rate (SAR) increased with increasing size of Fe 3 O 4 with the maximum values of 136.7 and 23,4 W/g under an applied magnetic field of 25.7 kA/m and 267 kHz for Fe 3 O 4 ~13 nm, Fe 3 O 4 ~13 nm@Au NPs, respectively, exhibiting high heating efficient capabilities and indicating potential use for magnetic hyperthermia.