An adapted Coffey model for studying susceptibility losses in interacting magnetic nanoparticles

作者：Osaci Mihaela; Cacciola Matteo

来源：Beilstein Journal of Nanotechnology, 2015, 6: 2173-2182.

DOI：10.3762/bjnano.6.223

• hyperthermia
• magnetic nanoparticles
• relaxation process
• specific loss power
• susceptibility losses

Background: Nanoparticles can be used in biomedical applications, such as contrast agents for magnetic resonance imaging, in tumor therapy or against cardiovascular diseases. Single-domain nanoparticles dissipate heat through susceptibility losses in two modes: Neel relaxation and Brownian relaxation.
Results: Since a consistent theory for the Neel relaxation time that is applicable to systems of interacting nanoparticles has not yet been developed, we adapted the Coffey theoretical model for the Nel relaxation time in external magnetic fields in order to consider local dipolar magnetic fields. Then, we obtained the effective relaxation time. The effective relaxation time is further used for obtaining values of specific loss power (SLP) through linear response theory (LRT). A comparative analysis between our model and the discrete orientation model, more often used in literature, and a comparison with experimental data from literature have been carried out, in order to choose the optimal magnetic parameters of a nanoparticle system.
Conclusion: In this way, we can study effects of the nanoparticle concentration on SLP in an acceptable range of frequencies and amplitudes of external magnetic fields for biomedical applications, especially for tumor therapy by magnetic hyperthermia.

• 出版日期2015-11-19