Characterization of nanoparticles in a media using multilevel models of magnetic dynamics

In order to extract quantitative information about characteristics of the magnetic nanoparticles in a media it is necessary to define a model of the magnetic dynamics for treating self-consistently the whole set of the experimental data, particularly, the evolution of Mossbauer spectral shape with temperature and external magnetic field as well as the magnetization curves. We have developed such a model and performed such an analysis of the temperature- and magnetic field-dependent spectra and magnetization curves by the example of nanoparticles injected into laboratory mice. This allowed us to reliably evaluate changes in the characteristics of the residual particles and their chemical transformation to paramagnetic ferritin-like forms in animals organs as a function of time. Actually, the approach makes it possible to quantitatively characterize biotransformation and biodegradation of magnetic nanoparticles delivered in a living organism.