title: In situ synthesis and characterization of magnetic nanoparticles in shells of biodegradable polyelectrolyte microcapsules.
abstract: Hollow microcapsules with the shell composed of biodegradable polyelectrolytes modified with the maghemite nanoparticles were fabricated by in situ synthesis. The nanoparticles were synthesized from the iron salt and the base directly on the capsule shells prepared by "layer by layer" technique. An average diameter of the capsule was about 6.7 μm while the average thickness of the capsule shell was 0.9 μm. XRD, HRTEM, Raman and Mössbauer spectroscopy data revealed that the iron oxide nanoparticles have the crystal structure of maghemite γ-Fe2O3. The nanoparticles were highly monodisperse with medium size of 7.5 nm. The Mössbauer spectroscopy data revealed that the nanoparticles have marked superparamagnetic behavior which was retained up to room temperature due to slow spin relaxation. Because of that, the microcapsules can be handled by an external magnetic field. Both these properties are important for target drug delivery. Based on the Mössbauer spectroscopy data, the spin blocking temperatures TB of about 90K was found for the particles with size D≤5 nm and TB≈250 K for particles with D≥6 nm. The anisotropy constants K were determined using the superparamagnetic approximation and in the low temperature approximation of collective magnetic excitation.
authors.affiliation: Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333, Russia.
authors.forename: I S
authors.initials: IS
authors.lastname: Lyubutin
authors.affiliation: Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333, Russia. Electronic address: sergey.s.starchikov@gmail.com.
authors.forename: S S
authors.initials: SS
authors.lastname: Starchikov
authors.affiliation: Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333, Russia.
authors.forename: T V
authors.initials: TV
authors.lastname: Bukreeva
authors.affiliation: National Research Center "Kurchatov Institute", pl. Akademika Kurchatova 1, Moscow 123182, Russia.
authors.forename: I A
authors.initials: IA
authors.lastname: Lysenko
authors.affiliation: Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333, Russia.
authors.forename: S N
authors.initials: SN
authors.lastname: Sulyanov
authors.affiliation: Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333, Russia.
authors.forename: N Yu
authors.initials: NY
authors.lastname: Korotkov
authors.affiliation: Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333, Russia.
authors.forename: S S
authors.initials: SS
authors.lastname: Rumyantseva
authors.affiliation: Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333, Russia.
authors.forename: I V
authors.initials: IV
authors.lastname: Marchenko
authors.affiliation: Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333, Russia.
authors.forename: K O
authors.initials: KO
authors.lastname: Funtov
authors.affiliation: Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333, Russia; National Research Center "Kurchatov Institute", pl. Akademika Kurchatova 1, Moscow 123182, Russia.
authors.forename: A L
authors.initials: AL
authors.lastname: Vasiliev
mesh_terms: D002214:Capsules / Q000138:chemical synthesis* / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D015204:Spectroscopy, Mossbauer; D013059:Spectrum Analysis, Raman; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D002214:Capsules; D005290:Ferric Compounds; D058185:Magnetite Nanoparticles; C000499:ferric oxide
keywords: Magnetic properties; Mössbauer spectroscopy; Nanostructured materials