Effect of Functional Magnetic Particles on Radiofrequency Capacitive Heating

Abstract

Magnetic particles (magnetite) were used to make radiofrequency (RF) capacitive hyperthermia effective to a specific site. In an agar phantom experiment, a magnetite-containing agar piece was buried in a large agar phantom and heated by an 8 MHz-RF capacitive heating device. The magnetite-containing agar piece was heated more than the magnetite-free agar phantom, and the specific adsorption rate in the phantom was increased 1.5 times by the magnetite particles. The temperature distribution in the large agar phantom showed that the highest temperature was obtained at the center of the magnetite-containing piece. The rate of temperature increase was approximately proportional to the magnetite concentration to the power 0.8. This method was applied to an in vivo experiment using a pig. Magnetite was prepared as a colloidal material dispersed in a carboxymethylcellulose solution (CMC-Mag) and intramuscularly injected in the pig femur. As a result of 8 MHz-RF heating, the temperature at the CMC-Mag-injected point increased to over 43°C after 7 min, while the temperature at a point without magnetite was under 40°C at the same time. The specific adsorption rate in the magnetite-containing tissue was twice that of the magnetite-free tissue. In addition, the time required to reach a temperature of over 43°C was only 7 min, while it was over 15 min in the case without the CMC-Mag.

A review on hyperthermia via nanoparticle-mediated therapy

“…The lower pH within the endosome allows an easy passage for the drug release into the target area. Magnetite cationic liposomes (MCLs), one of the groups of cationic magnetic particles, can be used as carriers to introduce magnetite nanoparticles into target cells since their positively charged surface interacts with the negatively charged cell surface; furthermore, they find applications in diverse hyperthermic treatments [9,11,13]. Magnetite nanoparticles conjugated with antibodies (antibody-conjugated magnetoliposomes, AMLs) have enabled tumour-specific contrast enhancement in MRI via systemic administration.…”

“…al. [11] demonstrated that magnetic nanoparticles serve as a medium that induces efficient heat generation in RFcapacitive heating. In an in-vivo experiment, they observed that heat generation using magnetic nanoparticles was similar to that using inductive heating employing an alternating magnetic field.…”

“…In contrast, other tissues that have not been injected with MCL do not experience an increase in temperature beyond 108:5 o F even if picked up with an electrode. Therefore, magnetic nanoparticles are considered to be a promising heat-generating medium not only for inductive heating but also for capacitive hyperthermia [12].…”

“…A correlation between erysipelas (a streptococcal skin infection) and tumour regression had been observed for over a century before William Coley in 1891 [1] first documented evidence of a relationship between infection and cancer regression in sarcoma patients. Ever-expanding research on the hyperthermic treatment of cancer has been sustained over the past four decades [1][2][3][4][5][6][7][8][9][10][11][12]. In some hyperthermia treatments, the patient's blood is warmed up by an external device before it is re-transfused to the target volume (e.g.…”

Histopathological evaluation of tumor necrosis and volume after cyanogenic chemotherapy

“…The determination of tumor inhibition was performed using the calculating tumor volume according to the following formula 10,11 :…”