title: Epithelial internalization of superparamagnetic nanoparticles and response to external magnetic field.
abstract: Superparamagnetic magnetite nanoparticles (MNP) coated with silica were synthesized and chronically implanted into the middle ear epithelial tissues of a guinea pig model (n=16) for the generation of force by an external magnetic field. In vivo limitations of biocompatibility include particle morphology, size distribution, composition and mode of internalization. Synthesis of MNP was performed using a modified precipitation technique and they were characterized by transmission electron microscopy, X-ray diffractometry and energy dispersive spectroscopy, which verified size distribution, composition and silica encapsulation. The mechanism for internalizing 16+/-2.3 nm diameter MNP was likely endocytosis, enhanced by magnetically force. Using sterile technique, middle ear epithelia of tympanic membrane or ossicles was exposed and a suspension of particles with fluoroscein isothiocyanate (FITC) label applied to the surface. A rare earth, NdFeBo magnet (0.35 T) placed under the animal, was used to pull the MNP into the tissue. After 8 days, following euthanasia, tissues were harvested and confocal scanning laser interferometry was used to verify intracellular MNP. Displacements of the osscicular chain in response to an external sinusoidal electromagnetic field were also measured using laser Doppler interferometry. We showed for the first time a physiologically relevant, biomechanical function, produced by MNP responding to a magnetic field.
authors.affiliation: Department of Physiology, Oklahoma University Health Sciences Center, 940 S.L. Young Blvd., Room 634, Oklahoma City, OK 73190, USA. ken-dormer@ouhsc.edu
authors.forename: Kenneth
authors.initials: K
authors.lastname: Dormer
authors.forename: Charles
authors.initials: C
authors.lastname: Seeney
authors.forename: Kevin
authors.initials: K
authors.lastname: Lewelling
authors.forename: Guoda
authors.initials: G
authors.lastname: Lian
authors.forename: Donald
authors.initials: D
authors.lastname: Gibson
authors.forename: Matthew
authors.initials: M
authors.lastname: Johnson
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D004432:Ear, Middle / Q000166:cytology / Q000502:physiology / Q000528:radiation effects; D004574:Electromagnetic Fields; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects; D005260:Female; D006168:Guinea Pigs; D008297:Male; D008422:Materials Testing; D008846:Micromanipulation / Q000379:methods*; D043942:Nanotubes / Q000528:radiation effects* / Q000648:ultrastructure; D010316:Particle Size; D010812:Physical Stimulation / Q000379:methods*; D013314:Stress, Mechanical
chemical_list: D001672:Biocompatible Materials