Petr Mikhailovich Vetoshko

Non‐Invasive in vivo Mapping and Long‐Term Monitoring of Magnetic Nanoparticles in Different Organs of Animals

Quantitative detection of magnetic nanoparticles (MP) in vivo is very important for various biomedical applications. Our original detection method based on non‐linear MP magnetization has been modified for non‐invasive in vivo mapping of the MP distribution among different organs of rats. A novel highly sensitive room‐temperature device equipped with an external probe has been designed and tested for quantification of MP within 20‐mm depth from the animal skin. Results obtained by external in vivo scanning of rats by the probe and ex vivo MP quantification in different organs of rats well correlated. The method allows long‐term in vivo study of MP evolution, clearance and redistribution among different organs of the animal. Experiments showed that dynamics in vivo strongly depend on MP characteristics (size, material, coatings, etc.), site of injection and dose. The developed detection method combined with the magnetic nanolabels can substitute the radioactive labeling in many applications.

Modeling of Magnetization Distribution Near Shaped Boundary of Garnet Film Core in Fluxgate Magnetometer

Micromagnetic modeling of magnetization in-plane distribution near shaped boundary of garnet film was made to analyze the possibility to prevent chaotic formation of magnetic flux distortions in a fluxgate disc-like core excited by rotating magnetic field. Calculations made in the limit of zero anisotropy for sinusoidal, rectangular, and cogged (with right angle) boundaries show regular macroscopic vortex formation and annihilation in opposite phases of external magnetic field inside every apex of garnet film shaped boundary. Vortices are formed due to magnetostatic conservation of magnetization initial local direction along smooth or straight boundaries of the film during the whole period of rotation. Vortices near smooth curved boundary exhibit a stability range in the external field that exceeds that near rectangular and cogged shapes by an order of magnitude. Transformations of vortex states and low field saturation near broken line boundary are explained by peculiarities of exchange energy caused by mutually perpendicular spin orientations along adjacent straight sides of right angles. Calculation results show the way for control of magnetization distribution distortions in fluxgate garnet disc core by film boundary shape.