N.C.S.R. "Demokritos"


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Efficient magnetic heating by highly charged coated Maghemite Nanoparticles for cancer treatment

One of the most significant challenges implementing colloidal magnetic nanoparticles in medicine is the efficient heating of micro litre quantities, by applying a low frequency alternating magnetic field. The ultimate goal is to accomplish non-surgically the treatment of millimeter size tumors. Here, we demonstrate the synthesis, characterization and in vivo efficiency of a dextran coated maghemite ferrofluid, with an exceptional response to magnetic heating. The difference to previous synthetic attempts is the high charge of the dextran coating. Specifically, in vitro 2 μl of the ferrofluid give an outstanding temperature rise of 33 0C within 10 minutes, while in vivo treatment, by infusing 150 μl of the ferrofluid in animal model (rat) glioma tumors, cause an impressive cancer tissue dissolution.
A remarkable property of these colloidal systems is the considerable heating effect due to several loss mechanisms when subjected to an alternating (AC) magnetic field. This has been utilized for applications in cancer therapy. Specifically, ferrofluids are selectively deposited in tumors, and subsequently irradiated with an AC magnetic field, in the radio-frequency range 50 kHz – 1 MHz (magnetic heating). The energy absorption and the respective heat delivery focused on the tumor, without influencing the surrounding healthy tissue. However, by scaling the irradiated volume down to a few millimetres, which is desirable for treating tumors at the limit of the medical diagnosis resolution without affecting the healthy tissue, the efficiency of the method decreases dramatically, due to the extremely small quantity of ferrofluid that can be adsorbed in tumors of such small size. Our initial aim was to find ways to increase the efficiency of the magnetic heating of biocompatible ferrofluids that are produced with standard wet chemistry methods.
To summarize, we have investigated the synthesis, the structural, magnetic properties of highly charged coated maghemite nanoparticles with remarkable absorption of an AC magnetic field at very small quantities and demonstrate their in vivo efficiency for hyperthermia treatment of small size tumors. The exceptional heating performance of the produced ferrofluid is due to (i) the appropriate size and excellent magnetic properties of the core nanoparticles, and (ii) the high surface charge of the dextran coating that produces homogeneous and stable nanoparticle dispersion, resulting to minimal interparticle interactions and maximum energy absorption. To the best of our knowledge the microlitre ferrofluid quantities, used for magnetic heating in both in vitro and in vivo experiments, are the smallest reported in the literature.

(Research performed by the NMR group)

for more information: Ioannis Rabias

Department of Materials Science, N.C.S.R. "Demokritos", 153 10 Aghia Paraskevi, Attiki, phone: +30 210 6503381, fax: +30 210 6519430
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