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Le Touquet – Paris-Plage, France

Alphandery E.,University Pierre and Marie Curie | Faure S.,Nanobacterie SARL | Raison L.,French National Center for Scientific Research | Duguet E.,French National Center for Scientific Research | And 2 more authors.
Journal of Physical Chemistry C | Year: 2011

In this work, we examined mechanisms of heat production by whole intact cells of the magnetotactic bacterium Magnetospirillum magneticum strain AMB-1, as well as by their extracted chains of magnetosomes or extracted individual magnetosomes when exposed to an oscillating magnetic field of frequency 108 kHz and field amplitudes 23 and 88 mT. In this study, magnetosomes did not contain magnetite as the magnetite oxidized to maghemite. For intact bacterial cells that contain chains of magnetosomes, heat is generated through hysteresis losses, yielding specific absorption rates (SARs) of 115 ± 12 W/g Fe at 23 mT and 864 ± 9 W/gFe at 88 mT. When the chains of magnetosomes are extracted from the bacterial cells and exposed to the same magnetic field, the heat-producing mechanism includes an additional contribution that is due to their rotation in the magnetic field. This contribution appeared to result in higher observed SARs of 864 ± 13 W/gFe at 23 mT and 1242 ± 24 W/gFe at 88 mT. SAR values of 529 ± 14 W/gFe at 23 mT and 950 ± 18 W/g Fe at 88 mT were obtained with individual magnetosomes whose membranes had been removed. © 2010 American Chemical Society.


Alphandery E.,Nanobacterie SARL | Alphandery E.,University Pierre and Marie Curie
Journal of Cancer | Year: 2014

In this article, the use of different types of thermotherapies to treat breast cancer is reviewed. While hyperthermia is most commonly used as an adjuvant in combination with radiotherapy, chemotherapy, targeted therapy or cryotherapy to enhance the therapeutic effect of these therapies, thermoablation is usually carried out alone to eradicate small breast tumors. A recently developed thermotherapy, called magnetic hyperthermia, which involves localized heating of nanoparticles under the application of an alternating magnetic field, is also presented. The advantages and drawbacks of these different thermotherapies are highlighted. © Ivyspring International Publisher.


Alphandery E.,University Pierre and Marie Curie | Carvallo C.,University Pierre and Marie Curie | Menguy N.,University Pierre and Marie Curie | Chebbi I.,Nanobacterie SARL
Journal of Physical Chemistry C | Year: 2011

We report the magnetic properties and heating efficiency of cobalt doped chains of magnetosomes extracted from magnetotactic bacteria for applications in alternative magnetic field cancer therapy. The changes of the magnetic properties of the chains of magnetosomes observed in the presence of cobalt are characterized by an enhancement of the magnetocrystalline anisotropy from K eff ∼ 12 KJ/m3 in the absence of cobalt up to K eff ∼ 104 KJ/m3 in the presence of cobalt. We show that these changes are only observed for the magnetosomes organized in chains. Furthermore, the SAR of the extracted chains of magnetosomes mixed in solution and exposed to an oscillating magnetic field of field amplitude 80 mT and frequency 183 kHz is shown to increase from ∼400 W/gFe for the undoped chains of magnetosomes up to ∼500 W/gFe for the cobalt doped chains of magnetosomes. © 2011 American Chemical Society.


Alphandery E.,University Pierre and Marie Curie | Alphandery E.,Nanobacterie SARL | Faure S.,Nanobacterie SARL | Seksek O.,University Pierre and Marie Curie | And 3 more authors.
ACS Nano | Year: 2011

Chains of magnetosomes extracted from AMB-1 magnetotactic bacteria are shown to be highly efficient for cancer therapy when they are exposed to an alternative magnetic field. When a suspension containing MDA-MB-231 breast cancer cells was incubated in the presence of various amounts of extracted chains of magnetosomes, the viability of these cells remained high in the absence of an alternative magnetic field. By contrast, when this suspension was exposed to an alternative magnetic field of frequency 183 kHz and field strengths of 20, 40, or 60 mT, up to 100% of these cells were destroyed. The antitumoral activity of the extracted chains of magnetosomes is demonstrated further by showing that they can be used to fully eradicate a tumor xenografted under the skin of a mouse. For that, a suspension containing ∼1 mg of extracted chains of magnetosomes was administered within the tumor and the mouse was exposed to three heat cycles of 20 min, during which the tumor temperature was raised to ∼43 °C. We also demonstrate the higher efficiency of the extracted chains of magnetosomes compared with various other materials, i.e., whole inactive magnetotactic bacteria, individual magnetosomes not organized in chains, and two different types of chemically synthesized superparamagnetic iron oxide nanoparticles currently tested for alternative magnetic field cancer therapy. The higher efficiency of the extracted chains of magnetosomes compared with that of the other nanoparticles is attributed to three factors: (i) a specific absorption rate higher for the magnetosomes than for the chemically synthesized superparamagnetic iron oxide nanoparticles, (ii) a more uniform heating for the chains of magnetosomes than for the individual magnetosomes and (iii) the ability of the chains of magnetosomes to penetrate within the cancer cells or bind at the cell membrane following the application of the alternative magnetic field, which enables efficient cell destruction. Biodistribution studies revealed that extracted chains of magnetosomes administered directly within xenografted breast tumors progressively left the tumors during the 14 days following their administration and were then eliminated in large proportion in the feces. © 2011 American Chemical Society.


Alphandery E.,University Pierre and Marie Curie | Alphandery E.,Nanobacterie SARL | Amor M.,University Pierre and Marie Curie | Amor M.,CNRS Paris Institute of Global Physics | And 3 more authors.
Applied Microbiology and Biotechnology | Year: 2012

The introduction of various iron-chelating agents to the Magnetospirillum magneticum strain AMB-1 bacterial growth medium stimulated the growth of M. magneticum strain AMB-1 magnetotactic bacteria and enhanced the production of magnetosomes. After 7 days of growth, the number of bacteria and the production of magnetosomes were increased in the presence of iron-chelating agents by factors of up to ∼2 and ∼6, respectively. The presence of iron-chelating agents also produced an increase in magnetosome size and chain length and yielded improved magnetosome heating properties. The specific absorption rate of suspensions of magnetosome chains isolated from M. magneticum strain AMB-1 magnetotactic bacteria, measured under the application of an alternating magnetic field of average field strength ∼20 mT and frequency 198 kHz, increased from ∼222 W/gFe in the absence of iron-chelating agent up to ∼444 W/gFe in the presence of 4 μM rhodamine B and to ∼723 W/gFe in the presence of 4 μM EDTA. These observations were made at an iron concentration of 20 μM and iron-chelating agent concentrations below 40 μM. © Springer-Verlag 2012.

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