Configurable High-Frequency Alternating Magnetic Field Generator for Nanomedical Magnetic Hyperthermia Applications

Abstract

This article shows the use of a high-frequency Full-Bridge inverter to design an alternating magnetic field generator for experimental studies on anti-cancer treatment with magnetic nanoparticles. In magnetic hyperthermia, nanoparticles are used to raise the pathological cancerous cell's temperature high enough to induce their death by apoptosis, but not as high as to destroy them by thermal ablation of the whole tissue volume, consequently leaving healthy cells alive. Conventionally, sinusoidal alternative magnetic fields are used to heat the nanoparticles, which can be more easily produced than other waveforms. However, there are no theoretical nor experimental reasons to chose the sinusoidal waveform. This work aims to develop an improved power system to study the effect of different waveforms of the magnetic field on the heat production when exciting magnetic nanoparticles, aiming at demonstrating that other waveforms can be much more efficient in producing heat than conventional sinusoids. To prove our hypothesis, we designed an inverter able to generate four waveforms at high frequencies and a fifth sinusoidal signal derived by a resonant capacitor, in the range of 100 kHz to 1 MHz and up to 10 mT of peak intensity. Also, we used SiC devices to process high currents at high switching frequencies efficiently. Additionally, to enhance the system efficiency, Zero-Voltage Switching is used to reduce switching losses and minimize electromagnetic noise and interference. The experimental results obtained with non-sinusoidal waveforms have shown a remarkable performance improvement compared to classical sine wave excitation. The nanoparticles' heat dissipation depends on the applied alternating magnetic field's signal slope, signal frequency, and peak field intensity. We conclude that further work deserves to be done to find the optimum work conditions in function of the used particle and biological environment, to test if this type of magnetic field generator could overcome the conventional system's performance.

Enhancing Magnetic Hyperthermia Nanoparticle Heating Efficiency with Non-Sinusoidal Alternating Magnetic Field Waveforms

“…Furthermore, following the calculation of n%∆P * i,j , the results showed the dependency of the thermal power generated by the NP on the waveform's slope, as it was previously hypothesized in Garcia et al [28], Zeinoun et al [30] and Urbano et al [29]. However, further investigation is required in order to determine the factor that TR and TT are aligned exponentially, while TS, TP and SN are aligned horizontally.…”

“…It is able to generate 4 unconventional signals in addition to a 5th sinusoidal (SN) for comparison (see Figure 2 The initial aim was to generate a pure square signal; however, this proved extremely difficult in inverter applications, so an "almost-square signal" was generated, which is TS. The AMF can generate up to 100 A pk−pk output current and operate at frequencies of 100 kHz to 1 MHz at a 100 kHz frequency step.The design is thoroughly described in Zeinoun et al [30].…”

Fabrication of PEGylated SPIONs-Loaded Niosome for Codelivery of Paclitaxel and Trastuzumab for Breast Cancer Treatment: In Vivo Study

“…Therefore, when the mats were exposed to the AMF, TbNs were affected by AMF too. Hyperthermia by AMF is known as a promising treatment to remove tumors by heating tumor tissues to between 43 and 46 °C for some time without any lethal effect on adjacent tissues . TbNs, due to the presence of Fe 3 O 4, (SPIONs) are affected by AMF, which ends up in thermal energy dissipation in the surrounding medium or tissue.…”

“…Hyperthermia by AMF is known as a promising treatment to remove tumors by heating tumor tissues to between 43 and 46 °C for some time without any lethal effect on adjacent tissues. 48 TbNs, due to the presence of Fe 3 O 4, (SPIONs) are affected by AMF, which ends up in thermal energy dissipation in the surrounding medium or tissue. Finally, by heating the tumor tissue and also targeted PTX delivery (because of the presence of Tmab as an antibody) there is a high chance of tumor removal.…”

Novel candidate theranostic radiopharmaceutical based on strontium hexaferrite nanoparticles conjugated with azacrown ligand

“…Although hyperthermia has shown high efficacy in cancer treatment, 16,27,28 this approach, requiring magnetic fields with frequencies ranging from tens of kHz to MHz, generates eddy currents inside healthy tissues that may cause adverse effects. 29 At the same time, the in vivo anti-tumour effect under a low-frequency magnetic field using hard magnetic particles is insufficiently studied.…”