Impact of magnetic field parameters and iron oxide nanoparticle properties on heat generation for use in magnetic hyperthermia

Abstract

Heating of nanoparticles (NPs) using an AC magnetic field depends on several factors, and optimization of these parameters can improve the efficiency of heat generation for effective cancer therapy while administering a low NP treatment dose. This study investigated magnetic field strength and frequency, NP size, NP concentration, and solution viscosity as important parameters that impact the heating efficiency of iron oxide NPs with magnetite (Fe3O4) and maghemite (γ-Fe2O3) crystal structures. Heating efficiencies were determined for each experimental setting, with specific absorption rates (SARs) ranging from 3.7 to 325.9 W/g Fe. Magnetic heating was conducted on iron oxide NPs synthesized in our laboratories (with average core sizes of 8, 11, 13, and 18 nm), as well as commercially-available iron oxides (with average core sizes of 8, 9, and 16 nm). The experimental magnetic coil system made it possible to isolate the effect of magnetic field parameters and independently study the effect on heat generation. The highest SAR values were found for the 18 nm synthesized particles and the maghemite nanopowder. Magnetic field strengths were applied in the range of 15.1 to 47.7 kA/m, with field frequencies ranging from 123 to 430 kHz. The best heating was observed for the highest field strengths and frequencies tested, with results following trends predicted by the Rosensweig equation. An increase in solution viscosity led to lower heating rates in nanoparticle solutions, which can have significant implications for the application of magnetic fluid hyperthermia in vivo.

Magnetic hyperthermia performance of magnetite nanoparticle assemblies under different driving fields

“…Hysteresis loss comes from the movement of domain walls, which is responsible for heating in larger sized ferromagnetic particles. 5 Herein, we are investigating on single domain magnetite NPs where the hysteresis loss is nonexistent. Magnetite NPs with diameters below 50 nm are single domain, and thus we can work within the macrospin approximation.…”

H-Field Contribution to the Electromagnetic Energy Deposition in Tissues Similar to the Brain but Containing Ferrimagnetic Particles, During Use of Face-Held Radio Transceivers

“…It has been very recently proved that the mechanism of heating is highly dependent on multiple factors [32][33][34][35]: a) magnetic particle sizes (and in correlation with field frequency); b) nanoparticles compositions; c) particle concentrations; d) magnetic fluid viscosity; e) particle's surface; f) shape anisotropy; g) interface exchange anisotropy; h) dipolar interactions. It is demonstrated that particles sizes influence the types of relaxation processes that conduct magnetic heating.…”

Nanoparticles in biomedical applications

“…Coating with a shell offers many advantages such as it prevents agglomeration and helps with further functionalisation and conjugation to proteins, enzymes, antibodies and anticancer drugs. Iron oxide nanoparticles have been investigated for use in magnetic hyperthermia treatment [20,21,[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46]55], targeted drug delivery and contrast agents in magnetic resonance imaging (MRI) 34,41,56,62]. The magnetic properties of iron oxide nanoparticles can be improved by doping with magnetically susceptible elements such as manganese (Mn), cobalt (Co) and nickel (Ni) [103] …”

“…A lot of literature have focused on iron oxide nanoparticles because of their superior chemical, biological and magnetic properties including chemical stability, non-toxicity, biocompatibility, high saturation magnetisation and high magnetic susceptibility [5][6][7][8]. These properties allow for its use in many biomedical applications; bioimaging 34,41,56,62], hyperthermia [20,21,[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46]55], drug delivery , cell labelling [26,70] and gene delivery [71][72][73][74][75][76][77]. From our most recent review, it was seen that other magnetic nanomaterials such as Fe-Co, Cu-Ni, Fe-Ni, Co-Fe 2 O 4 and Mn-Fe 2 O 4 , nanoparticles are being investigated for use in bioimaging [78][79][80][81][82][83][84][85][86]…”