Magnetic Hyperthermia in the 400–1,100 kHz Frequency Range Using MIONs of Condensed Colloidal Nanocrystal Clusters

Abstract

In the current study, we explored the magnetic hyperthermia performance of condensed–clustered magnetic iron oxide nanoparticles (MIONs) in the range of 400 kHz to 1.1 MHz at low field amplitudes. The strong interparticle interactions, present in such systems, can influence the hyperthermia power produced by MIONs. Herein, the heat dependence, as an increasing function of frequency, with a fixed magnetic field strength of 3 mT is recorded, revealing a direct relationship between the two physical quantities and a high heating efficiency for the condensed–clustered MIONs. In particular, the specific loss power (SLP) (or specific absorption rate [SAR]) parameter, which is the ratio of the heat power in watts produced per nanoparticle mass in grams, is linear to a good degree to the oscillating frequency with a step of roughly 30 W/g per 100 kHz increase. In addition, all the measurements were within the safety limits proposed by Hergt and Dutz criterion of H f ≤ 5 × 109A/ms for clinical application of magnetic fluid hyperthermia (MFH). Finally, the measured data of temperature vs. time at each frequency were interpreted in terms of simple thermodynamic arguments, thus extracting useful thermodynamic parameters for the heat power generated by the condensed–clustered MIONs.

LAPONITE® nanodisk-“decorated” Fe3O4 nanoparticles: a biocompatible nano-hybrid with ultrafast magnetic hyperthermia and MRI contrast agent ability

“…Regarding iron oxide nanomaterials, the SAR values presented here are among the highest compared to the literature (Table S1, ESI†) in terms of magnetic field and frequency conditions and are comparable or even better than the iron oxide cubes, 50,75 rods, 20 tubes, rings/hollow, 49 multicores, 71 assemblies, 76,77 branched, 72 and cube assemblies, 23 which have been recently reported. Among them, some materials reveal extremely high SAR values, in the order of a few thousand W g −1 , but we have to notice, taking into consideration the linear dependence with the frequency 52,78 that this is mainly due to the very high frequency up to 700 kHz. In addition, it should be noted that these frequencies are much higher than the recommended frequency for human exposure (lower than 200 kHz).…”

“…The frequency dependence on the produced power is almost linear in a wide frequency range. 52 However, there are limits of human exposure for both, with the recommended frequency proposed to be about 200 kHz or lower. 53 Selected data associated with the morphology and size effects combined with hyperthermia conditions (magnetic field and frequency) in relation to the SAR values, and therefore magnetic hyperthermia performance, are summarized in Table S1 in the ESI †…”

Water-Dispersible Fe3O4 Nanoparticles Modified with Controlled Numbers of Carboxyl Moieties for Magnetic Induction Heating

“…As can be seen from the results, all SAR values were around 35 W/g Fe, and the maximum SAR value reached at 38.3 W/g Fe in 10 mg/mL of aqueous dispersion. The heating property indicated that it is anticipated to meet application requirements in hyperthermia with optimization of the core particle. − Bao et al reported the size effect on the heating efficiency of PEG-modified Fe 3 O 4 NPs . Their results showed that the SAR values of the particles with mean sizes of 6 and 8 nm were 8.35 and 30.0 W/g Fe, respectively, at the conditions of 20.7 kA/m and 325 kHz.…”

Optimisation of the Flame Spheroidisation Process for the Rapid Manufacture of Fe3O4-Based Porous and Dense Microspheres

“…Moreover, magnetic hyperthermia effects may be achieved through the application of weak magnetic fields (<7.95 kA/m) [ 3 ]; hence, relatively low magnetic fields were used for these Ca 2 Fe 2 O 5 microsphere induction heating studies. Furthermore, the field frequency (204 kHz) used was within the clinically accepted range for magnetic hyperthermia [ 3 , 30 , 50 , 51 , 52 , 53 , 54 , 55 ]. Additionally, in the present induction coil experiments the target temperature was achieved rapidly (~40 s), indicating that these microsphere products are promising candidates for reduced periods of magnetic hyperthermia exposure, thereby preventing and reducing patient discomfort [ 3 ].…”