High intrinsic loss power of multicore magnetic nanoparticles with blood-pooling property for hyperthermia

Abstract

Magnetic hyperthermia is a promising application of magnetic nanoparticles (MNPs) in cancer therapy. It is important to consider and optimize the parameters that affect heat dissipation, such as particle diameters, structures, and surface coatings. In this study, we measured the magnetic properties of two superparamagnetic nanoparticles under DC and AC magnetic fields. Resovist is approved to be used as a magnetic resonance imaging contrast agent. CMEADM-033-02, with the blood-pooling property and biocompatibility, exhibits high magnetization. The blood-pooling property makes it easier for MNPs to accumulate in tumors and tissue. While preparing samples, we aligned the easy axis of the samples using a DC magnetic field to enhance heat dissipation. We discussed the magnetic property in terms of magnetic relaxation associated with anisotropy energy. We observed that the peak frequency of Néel relaxation was considerably shifted owing to effectively changed anisotropy by the alignment of the easy axis. However, the change in the peak frequency of Néel relaxation could not be directly confirmed. Furthermore, we calculated the intrinsic loss power (ILP) and specific loss power (SLP) for heat dissipation from the areas of AC magnetization curves and estimated the SLP at 1 MHz to compare with the high heating characteristic of ILP that has been reported in a conventional study. We achieved equivalent ILP for heat dissipation as that reported in the study by aligning the easy axis of the MNPs with the blood-pooling property under a therapeutic condition.

Embracing Defects and Disorder in Magnetic Nanoparticles

“…[65][66][67][68] Consequently such nanoflowers, and similar dense iron oxide nanoparticle aggregates, excel at magnetic hyperthermia at low field amplitudes. [32][33][34][35][36][80][81][82] We attribute the increased heating to the magnetic softening, which results in increased χ''(ω) at low field amplitudes similar to single-core thermally treated nanocubes discussed before (Figure 2).…”

In Situ EXAFS-Based Nanothermometry of Heterodimer Nanocrystals under Induction Heating

“…In contrast, the local support environment of Pt–Fe 3 O 4 maintains a temperature of 35.25 ± 2.00 °C, resulting in a temperature difference of 73.60 ± 14.50 °C between the heterodimers and their local support environment. This result has significant implications for hyperthermia treatment since the placement of inductively active NCs close to cancer cells may lead to their death more efficiently while preserving the surrounding healthy cells. ,,,,,,, While the product of the applied field and frequency used in this study, which is approximately 6 × 10 10 A/m s, exceeds the maximum limit for safe exposure to humans, known as the Brezovich limit, it remains below the level seen in other studies, therefore maintaining clinical relevance through magnetic short pulse field exposure methods. , We additionally performed EXAFS-based nanothermometry under ambient conditions as seen in Figure S7, observing no changes compared to the samples measured under N 2 in the presence of 1-propanol.…”

“…Unraveling the relationship between induction heating and the working temperature of a material is crucial for the applications discussed previously. In catalysis, the temperature of the catalyst provides the thermal energy needed to overcome the activation barrier of the desired reaction. ,,, Despite the importance of inductive heating of NCs, the understanding of the relationship between nanoscale induction heating and the final temperature remains poor, ,,− with specific examples reported for iron alloys ,,, and iron oxide. , This is especially true in studies that focus on the inductive heating of NCs. ,− ,− Some studies report a uniform temperature distribution between NCs and their local support environment, − ,,,,,,− while others report a thermal difference between the two. − Many of the studies reporting a uniform temperature distribution come from experimental hyperthermia treatments − while those reporting a temperature difference come mainly from theory, especially with arguments for ballistic heat transfer at the nanoscale. − , …”

“…To resolve this contention, we implement thermometry on the scale of several nanometers, or nanothermometry, to understand the thermal properties of NCs. , These techniques have been applied to a variety of materials from Au, , Pt, rare earth elements, , and iron oxide. ,− ,,,, Nanothermometry can be performed using temperature-dependent luminescence − or phosphorescence, ,− high-resolution thermal imaging, , and scanning thermal microscopy . We implement in situ extended X-ray absorption fine structure (EXAFS) spectroscopy as a method of nanothermometry.…”

A Theoretical Analysis of Magnetic Particle Alignment in External Magnetic Fields Affected by Viscosity and Brownian Motion

“…Both magnetic alignment and relaxation are important in, for example, magnetic particle contrast imaging and quantification in magnetic resonance and particle imaging [8,9,[13][14][15], electromagnetic hyperthermia [6,7,16,17], theranostics [18][19][20], magnetorelaxometry [10,21,22], and navigation in the geomagnetic field [23][24][25][26][27]. Magnetic particle alignment at the nano-and micro-scale requires a complex approach for simulating a wide range of possible strengths of an acting external magnetic field.…”