Evaluation of magnetic nanoparticles for magnetic fluid hyperthermia

Abstract

Background: Magnetic nanoparticles (MNPs) generate heat when exposed to an alternating magnetic field. Consequently, MNPs are used for magnetic fluid hyperthermia (MFH) for cancer treatment, and have been shown to increase the efficacy of chemotherapy and/or radiation treatment in clinical trials. A downfall of current MFH treatment is the inability to deliver sufficient heat to the tumor due to: insufficient amounts of MNPs, unequal distribution of MNPs throughout the tumor, or heat loss to the surrounding environment. Objective: In this study, the objective was to identify MNPs with high heating efficiencies quantified by their specific absorption rate (SAR). Methods: A panel of 31 commercially available MNPs were evaluated for SAR in two different AMFs. Additionally, particle properties including iron content, hydrodynamic diameter, core diameter, magnetic diameter, magnetically dead layer thickness, and saturation mass magnetization were investigated. Results: High SAR MNPs were identified. For SAR calculations, the initial slope, corrected slope, and Box-Lucas methods were used and validated using a graphical residual analysis, and the Box-Lucas method was shown to be the most accurate. Other particle properties were identified and examined for correlations with SAR values. Positive correlations of particle properties with SAR were found, including a strong correlation for the magnetically dead layer thickness. Conclusions: This work identified high SAR MNPs for hyperthermia, and provides insight into properties which correlate with SAR which will be valuable for synthesis of next-generation MNPs. SAR calculation methods must be standardized, and this work provides an in-depth analysis of common calculation methods.

Magnetic Hyperthermia for Cancer Treatment: Main Parameters Affecting the Outcome of In Vitro and In Vivo Studies

“…The size, size distribution, and shape of a particular NM have a clear impact on its magnetic properties [ 31 ]. These parameters should ideally be optimized [ 32 ] so as to exhibit the highest heating power under a selected AMF frequency [ 33 , 34 , 35 ], while displaying minimal toxicity if not subjected to an external magnetic field. This optimization also minimizes the need to revise extrinsic parameters, such as the NM concentration or the AMF power.…”

“…Very distinct types of magnetic materials have been used for MHT purposes, including metal nanoparticles (e.g., Fe, Co, and Ni), metal alloy nanoparticles (e.g., FeCo, FePt, CoPt, and FePd), metal oxide nanoparticles (e.g., Fe 3 O 4 , Fe 2 O 3 , and MnO), ferrite nanoparticles (e.g., MnFe 2 O 4 , NiFe 2 O 4 , and ZnFe 2 O 4 ), metal-doped iron oxide nanoparticles (e.g., Mg, Mn, and Zn doped iron oxide), and core-shell magnetic nanoparticles (e.g., Fe@Fe 3 O 4 , Co@Co 2 P, and CoFe 2 O 4 @MnFe 2 O 4 ) [ 44 ]. Since the magnetic properties of the NMs depend on their size, shape, composition, and structure, these characteristics need to be crucially controlled during NMs synthesis [ 32 ]. As an example, magnesium-doped maghemite superparamagnetic nanoparticles with 100× higher heating power (see Section 2.3.1 ) than the commercial Resovist formulation allowed the induction of complete necrosis of glioblastoma cells by applying a low AMF ( Hf product = 1.22 × 10 9 A m −1 s −1 ) [ 45 ].…”

A High-Throughput Microfluidic Magnetic Separation (µFMS) Platform for Water Quality Monitoring

“…Here, two different kinds of particles were studied, IONs (Sigma-Aldrich < 50 nm) and our custom magnetic microdiscs (1.5 µm in diameter, 80 nm in thickness), which were simulated as spherical particles with three different hydrodynamic diameters (D hd ): 70 nm (lower bound), 618 nm (equivalent magnetic volume of microdisc: 1.24 × 10 −19 m 3 ), and 1.5 µm (upper bound). In the case of the IONs, they were simulated with hydrodynamic diameters of 50 nm as defined by Sigma-Aldrich (< 50 nm) and 124 nm considering the hydrodynamic diameter measured in [37], as well as many other diameters accounting for particle aggregation. In Supplementary Material Figure S4, all D hd simulated for IONs are shown with their respective capture efficiencies.…”

Heating technology for malignant tumors: a review

“…Magnetic nanoparticles (MNPs) were first proposed by Gilchrist et al [58]. Further developments have resulted in intriguing materials for clinical conductive heating [59][60][61]. When exposed to an external magnetic field, the magnetic materials will respond by aligning their atomic moments with the field, thus producing a magnetization that persists for a characteristic duration after the external magnetic field is removed [62,63].…”