Structural perspective on revealing heat dissipation behavior of CoFe₂O₄–Pd nanohybrids: great promise for magnetic fluid hyperthermia

Abstract

Loss mechanisms in fluid heating of cobalt ferrite (CFO) nanoparticles and CFO-Pd heterodimer colloidal suspensions are investigated as a function of particle size, fluid concentration and magnetic field amplitude. The...

Element-specific contributions to improved magnetic heating of theranostic CoFe2O4 nanoparticles decorated with Pd

“…Magnetometry data reveal a substantial impact of Pd decoration on the magnetic properties, in particular an increase of the magnetization in an external field of 6 T at 300 K (Table 1 ) by a factor of about 4 (2) for the small (large) CFO nanoparticles compared to the bare ones and changes in the magnetic susceptibility 8 . Admittedly, the high-field magnetization values for both bare samples are lower than some reported values in the literature which could be due to the presence of spin-disorder at the surface, different degrees of cation inversion 13 , anti-phase boundaries 14 , aging effects 25 , chelating agents especially citric acid 26 , and agent type for pH value of reaction medium 27 .…”

“…Their functionalities can be synergistically improved in hybrid nanostructures 2 – 4 leading to elaborate designs of theranostic nano-agents with both, therapeutic and diagnostic capabilities 5 – 7 . Since colloidal heterodimers can be efficiently utilized for a wide range of bioapplications, we had already introduced Pd decorated CFO nanoparticles for potential optical and magnetic hyperthermia applications 8 . Although some noble metals like gold and silver provide plasmonic behavior as a significant mechanism of photothermal therapy, they mostly exhibit diamagnetic properties that could lead to substantially reduced magnetization.…”

“…Therefore, it might be considered as a suitable candidate for the simultaneous plasmonic-magnetic hyperthermia bioapplications. Moreover, Pd decorations could improve the performance in photothermal therapeutic applications, the biocompatibility of CFO clusters, and the heat transfer efficiency in magnetic hyperthermia 8 . In particular, it has been recently shown that CFO-Pd heterodimers, i.e.…”

“…In particular, it has been recently shown that CFO-Pd heterodimers, i.e. CFO nanoparticles decorated with Pd nanoparticles, exhibit specific absorption rates in suspension of up to 66–68 W/g (normalized to the mass of magnetic material) that outperform commercially available ferrofluids used for magnetic heating by about a factor of two 8 .…”

“…Coming back to the doubling of the specific absorption rates of suspended CFO nanoparticles used for magnetic heating as mentioned above, the size, cation disorder and magnetic anisotropy have already been excluded as reasons for the enhanced magnetic heating upon decoration with Pd 8 . Moreover, a potentially induced magnetization of Pd clusters, which could be expected because of the Stoner-enhanced magnetic polarizability of Pd, cannot explain the observed changes in the magnetic response either, because the amount of Pd (< 2 wt%) is too small.…”