Tohoku University · Engineering
Professor Loi Tonthat's research lab specializes in the design and application of functional nanomaterials for biomedical theranostics, with a primary focus on magnetic hyperthermia and point-of-care diagnostics. The lab develops smart, self-regulating magnetic nanoparticles—such as Fe3O4@Au NPs and low-Curie-temperature ferromagnetic implants—for targeted cancer therapy and real-time temperature monitoring. Innovative approaches include wireless thermometry using magnetic field response and rapid, magnetic immunoassay-based detection of oral pathogens. The lab integrates materials synthesis, magnetic characterization, and biomedical evaluation to advance precision medicine solutions.
Figures are computed from collected data and may differ slightly.
Magnetic hyperthermia is very promising cancer therapy in which heating temperature is expected to be a key determinant for its success. Herein, we present a simple, real‐time, and high‐accuracy proportional‐integral‐derivative‐based temperature control system for magnetic hyperthermia using widely‐used induction heater and fiber optic thermometer. Our in vitro result shows that the temperature of clinically‐approved Resovist® (0.5 ml) was accurately controlled with very small overshoot (e.g., 4
Self-controlled heating mediators for magnetic hyperthermia are widely studied. In previous studies, we succeeded in developing a microsize thermosensitive ferromagnetic implant with low Curie temperature (FILCT). The FILCT was then coated with gold (Au-FILCT) to improve its heating efficiency for treating the human body. However, part of the magnetic field was shielded due to the conductive gold coating, thereby decreasing the possibility of our orientable pickup coil system for contactless tem
In this study, we aim to develop gold-coated Fe3O4 nanoparticles (Fe3O4@Au NPs) as theranostic agents for magnetic hyperthermia and CT imaging applications. The Fe3O4 NPs were synthesized via thermal decomposition method, and the gold was then deposited onto the surface of Fe3O4 NPs by reducing gold acetate at 190 °C. The average sizes of Fe3O4 and Fe3O4@Au NPs were 5.2 nm and 6.1 nm, respectively, which are effectively removed by the kidneys. The magnetization of Fe3O4@Au NPs (9.7 emu/g-Fe3O4)
This study describes a user-friendly and rapid detection system of oral bacteria in the liquid phase for point of care testing based on magnetic immunoassay. We focused on the dependence of the strength of external magnetic field required to switch the magnetic moments of nanoparticles bound to bacteria on the bacteria concentration. The results obtained indicate that the required field strength increases linearly as a function of log concentration of Porphyromonas gingivalis cultured in the ran
Recently, self-controlled heating mediators were widely investigated for magnetic hyperthermia. In our previous studies, we succeeded in developing a ferromagnetic implant with low Curie temperature (FILCT). Then, to improve the heating efficiency of FILCT, we coated it with gold. By utilizing the temperature-dependent permeability of FILCT, we proposed a wireless temperature measurement. However, the gold coating layer decreases the change in magnetic flux density caused by FILCT, thus decreasi
We present the synthesis and characterization of ultrasmall iron oxide/gold composite nanoparticles (Fe3O4@Au NPs) with different Fe3O4 sizes, along with an evaluation of their heating efficiency for potential use in magnetic hyperthermia (MH) applications. The Fe3O4 NPs of approximately 5, 10, and 13 nm were synthesized using the thermal decomposition method, followed by gold deposition via the reduction of gold acetate at 190 °C. The morphology, structure, and magnetic properties of as-prepare
In this study, we demonstrated experimental findings on the ultrafast heating capabilities of ultrasmall gold-coated iron oxide magnetic nanoparticles (MNPs) (Fe3O4 @ Au NPs) utilizing the ferromagnetic resonance (FMR) effect. A lab-made setup was employed to evaluate the FMR and temperature increment of NPs under FMR conditions. The resonant frequency of both Fe3O4 @ Au NPs and their uncoated Fe3O4 NPs was several GHz and increased with the strength of the applied dc field as accurately describ
Resovist®, a MRI contrast agent, has been gaining more attention due to its potential as a therapeutic agent in magnetic hyperthermia and a diagnostic agent in magnetic particle imaging. In this study, we examined the dependence of heating property quantified by the specific absorption rate (SAR) by manipulating the applied magnetic field amplitude and frequency ( H = 1.8–7.1 kA/m, f = 500 kHz, and H = 4.8 kA/m, f = 200–1000 kHz). The results indicate that the SAR was linearly proportional to am
Magnetic hyperthermia is a promising cancer therapy gaining great interest in recent years. In this therapy, in addition to magnetic particles, important elements include techniques for detecting the position and temperature of magnetic particles in a tumor region in determining the effectiveness of therapeutic heating. In previous studies, we developed a low invasive heating and wireless temperature measurement system for magnetic hyperthermia using a ferromagnetic implant with low Curie temper
Dumbbell-shaped hybrid nanoparticles, consisting of gold and iron oxide (Au-Fe3O4 NPs), show promise for magnetic hyperthermia cancer therapy. However, conventional synthesis methods using toxic iron pentacarbonyl (Fe(CO)5) raise safety concerns. We propose a safer approach using triiron dodecacarbonyl (Fe3(CO)12) as a precursor. We synthesize these NPs by initially reducing gold (III) chloride trihydrate with a tert-butylamine-borane complex at room temperature, yielding Au NPs. These Au NPs ar
Hyperthermia using magnetic particles is a very promising cancer therapy. In previous studies, we developed a mixture of magnetic micro/nanoparticles with high heating efficiency for tumor treatment and considerable change in permeability around therapeutic temperature for monitoring its temperature and position during heating. In this study, we examined experimentally the effect of applied magnetic field on the heating and permeability properties of the proposed mixture by manipulating the ampl
In magnetic hyperthermia, the temperature and localization of a ferromagnetic implant in a tumor region is vital in determining the effectiveness of therapeutic heating. We have developed a noninvasive wireless temperature measurement method by utilizing the magnetic permeability property of a ferromagnetic implant with low Curie temperature (FILCT) that varies with the temperature. In clinical settings, when the FILCT is injected into a tumor region, the position of the FILCT is expected to dev
Recently, the use of a ferromagnetic material in a soft‐heating method has garnered much attention as a novel method for cancer treatment. By concurrently using this material as a thermal probe, we are currently developing a minimally invasive heating and wireless temperature measurement system. To make the approach feasible in a clinical setting, it is vital to overcome the key challenge of heating the local tumor at a constant temperature. In previous conventional approaches, it was necessary
In this study, we prepared ultrasmall FeCo nanoparticles (NPs) with a high magnetic moment and examined their antigen-antibody reaction for biodetection applications. The FeCo NPs were collected from the FeCo-BaF2 nanogranular film with Fe:Co:Ba:F = 14:11:21:54 at.%, by dissolving the film in water since the BaF2 matrix was deliquescent. The size of FeCo NPs was ∼5 nm and the saturation magnetization was estimated to be ∼15.30 kG (149.0 emu/g). The Candida albicans antibodies (abcam ab53891)-con
In hyperthermia treatment, the accurate temperature measurement of tumor region is vital to determine the therapeutic effectiveness of heating. Conventional methods require thermal probes to be inserted invasively into tumor region. However, by using Ferromagnetic Implant with Low Curie Temperature (FILCT) as thermal probe, we have developed a wireless temperature measurement method that can noninvasively measure the temperature of tumor region from outside of the body. To make the approach feas
Open papers in the app to read, cite, and organize with AI.