Constrained growth of anisotropic magnetic δ-FeOOH nanoparticles in the presence of humic substances
Constrained growth of anisotropic magnetic δ-FeOOH nanoparticles in the presence of humic substances. Polyakov A.Yu., Goldt A.E., Sorkina T.A., Perminova I.V., Pankratov D.A., Goodilin E.A., Tretyakov Y.D. //CrystEngComm. 2012. V.14. №23. P.8097-8102.
Natural polyelectrolytes, humic substances, are suggested to control in situ growth of feroxyhyte nanoparticles of a highly reduced mean size and with enhanced colloidal stability in salt solutions. The feroxyhyte is formed as 2-5 nm thick and 20 × 20 nm wide nanoflakes due to the blocking of developing facets of feroxyhyte and constraints caused by diffusion limitations of ionic constituents across partially charged branches of humic substances.
Superparamagnetic iron oxide nanoparticles (SPIONs) are known as effective biocompatible agents for various biomedical applications like drug delivery, in vivo magnetic resonance imaging, cell and protein separation, hyperthermia and transfection. At present, synthesis and application of rods, disks, fibers, tubes, sheets, ellipsoids, dumbbell-shaped, acorn-shaped and other anisotropic nanoparticles attract growing attention because of their unique properties. Aggregation is a serious problem in the preparation and storage of such magnetic nanoparticles limiting considerably their practical applications. This problem can be solved by a surface modification of nanoparticles with organic macromolecules, their preparation in the presence of surfactants, application of hydrophilic, surface-active ligands improving biocompatibility and resulting in multifunctional nanoparticles for medical diagnostics.