Magnetic and transport properties of magneto-anisotropic nanocomposites for controlled drug delivery

Biodegradable polymeric film composites consisting of chitosan (Cht) and poly(3-hydroxybutyrate) (PHB) have been produced and used to encapsulate colloidal magnetite nanoparticles (MNPs) and a drug (dipyridamole). The magnetic organization of the MNPs induced by the exposure of the films to external magnetic fields was analyzed using ferromagnetic resonance and electron microscopy. A calculation of the relative abundance of aggregated nanoparticles showed that more than 14% of the particles were aggregated at total particle concentrations ranging from 3 to 8 mass %. Modification of the PHB-Cht composite matrix by nanoparticles has been proven to evoke changes in drug release kinetics, since the particles formed ordered magneto-anisotropic structures when exposed to external magnetic fields. The highest rate of transfer by diffusion was observed in the case of a nonisotropic matrix in which the orientation of particle aggregates coincided with the direction of the diffusion flux; the rate of drug release was the lowest in anisotropic matrices of biodegradable magneto-anisotropic nanocomposites with particle orientation perpendicular to the direction of diffusion. The physical reasons for the dependence of the release kinetics on the magnetic anisotropy of the samples are discussed. The results of the present study are indicative of the possibility of creating a new generation of therapeutic systems for the targeted delivery and sustained release of drugs controlled by a magnetic field.