Susumu Tokura

Hyperthermia and chemotherapy using Fe(Salen) nanoparticles might impact glioblastoma treatment

We previously reported that μ-oxo N,N’-bis(salicylidene)ethylenediamine iron [Fe(Salen)], a magnetic organic compound, has direct anti-tumor activity, and generates heat in an alternating magnetic field (AMF). We showed that Fe(Salen) nanoparticles are useful for combined hyperthermia-chemotherapy of tongue cancer. Here, we have examined the effect of Fe(Salen) on human glioblastoma (GB). Fe(Salen) showed in vitro anti-tumor activity towards several human GB cell lines. It inhibited cell proliferation, and its apoptosis-inducing activity was greater than that of clinically used drugs. Fe(Salen) also showed in vivo anti-tumor activity in the mouse brain. We evaluated the drug distribution and systemic side effects of intracerebrally injected Fe(Salen) nanoparticles in rats. Further, to examine whether hyperthermia, which was induced by exposing Fe(Salen) nanoparticles to AMF, enhanced the intrinsic anti-tumor effect of Fe(Salen), we used a mouse model grafted with U251 cells on the left leg. Fe(Salen), BCNU, or normal saline was injected into the tumor in the presence or absence of AMF exposure. The combination of Fe(Salen) injection and AMF exposure showed a greater anti-tumor effect than did either Fe(Salen) or BCNU alone. Our results indicate that hyperthermia and chemotherapy with single-drug nanoparticles could be done for GB treatment.

Parallel-connected bilayer coil for a 3.3-kW electric vehicle wireless charging system

Wireless charging is a key technology for electric vehicles. Owing to strict area limits within a vehicle, low heat generation is important for realizing a thermally plausible coil. We therefore propose a parallel-connected bilayer coil to reduce heat generation. The effectiveness of the proposed coil was demonstrated by experimental continuous operation for more than 8 hours.

The Behavior of Nano- and Micro-Magnetic Particles Under a High Magnetic Field Using a Superconducting Magnet

Magnetic force has been used for drug delivery, magnetic separation, and other kinds of micro- and nano-particle handling. As fundamental studies of these applications, we have investigated the visualization of the motion of micro-magnetic particles under a dynamic magnetic field. We have also studied the contactless grasp of a micro-magnetic particle suspended in a fluid by using coil currents. In the study, we have developed a method for quantitatively estimating the influencing forces. However, these experiments have limitations in the magnetic field strength of normal conducting electromagnets or permanent magnets. Therefore, much higher magnetic force is needed for the application to drug delivery or cell/DNA manipulation. High magnetic field generating high magnetic force saturates the magnetization of magnetic particles during the particle control, and the magnetic saturation influences the particle behavior. However, such behavior of magnetic particles has not been sufficiently studied yet. In this paper, the behavior of the particles nearly or fully saturated under the high magnetic field of a superconducting magnet was visualized successfully, and ferrite and feeble magnetic particles were introduced in order to gain insight into their behavior.