title: Poly(N,N-dimethylacrylamide)-coated maghemite nanoparticles for stem cell labeling.
abstract: Maghemite (gamma-Fe2O3) nanoparticles were obtained by the coprecipitation of Fe(II) and Fe (III) salts with ammonium hydroxide followed by oxidation with sodium hypochlorite. Solution radical polymerization of N,N-dimethylacrylamide(DMAAm) in the presence of maghemite nanoparticles yielded poly(N,N-dimethylacrylamide)(PDMAAm)-coated maghemite nanoparticles. The presence of PDMAAm on the maghemite particle surface was confirmed by elemental analysis and ATR FTIR spectroscopy. Other methods of nanoparticle characterization involved scanning and transmission electron microscopy, atomic adsorption spectroscopy (AAS), and dynamic light scattering (DLS). The conversion of DMAAm during polymerization and the molecular weight of PDMAAmbound to maghemite were determined by using gas and size-exclusion chromatography, respectively. The effect of ionic 4,4'-azobis(4-cyanovaleric acid) (ACVA) initiator on nanoparticle morphology was elucidated. The nanoparticles exhibited long-term colloidal stability in water or physiological buffer. Rat and human bone marrow mesenchymal stem cells (MSCs) were labeled with uncoated and PDMAAm-coated maghemite nanoparticles and with Endorem as a control. Uptake of the nanoparticles was evaluated by Prussian Blue staining, transmission electron microscopy, T(2)-MR relaxometry, and iron content analysis. Significant differences in labeling efficiency were found for human and rat cells. PDMAAm-modified nanoparticles demonstrated a higher efficiency of intracellular uptake into human cells in comparison with that of dextran-modified (Endorem) and unmodified nanoparticles. In gelatin, even a small number of labeled cells changed the contrast in MR images. PDMAAmcoatednanoparticles provided the highest T(2) relaxivity of all the investigated particles. In vivo MR imaging ofPDMAAm-modified iron oxide-labeled rMSCs implanted in a rat brain confirmed their better resolution compared with Endorem-labeled cells.
authors.affiliation: Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 16206 Prague 6, Czech Republic.
authors.forename: Michal
authors.initials: M
authors.lastname: Babic
authors.forename: Daniel
authors.initials: D
authors.lastname: Horák
authors.forename: Pavla
authors.initials: P
authors.lastname: Jendelová
authors.forename: Katerina
authors.initials: K
authors.lastname: Glogarová
authors.forename: Vít
authors.initials: V
authors.lastname: Herynek
authors.forename: Miroslava
authors.initials: M
authors.lastname: Trchova
authors.forename: Katarína
authors.initials: K
authors.lastname: Likavanová
authors.forename: Petr
authors.initials: P
authors.lastname: Lesný
authors.forename: Emil
authors.initials: E
authors.lastname: Pollert
authors.forename: Milan
authors.initials: M
authors.lastname: Hájek
authors.forename: Eva
authors.initials: E
authors.lastname: Syková
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000818:Animals; D002470:Cell Survival; D005290:Ferric Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*; D005780:Gelatin / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D051381:Rats; D012542:Scattering, Radiation; D017550:Spectroscopy, Fourier Transform Infrared; D013194:Staining and Labeling / Q000379:methods*
chemical_list: D000178:Acrylamides; D005290:Ferric Compounds; C429790:poly(N,N-dimethylacrylamide); C000499:ferric oxide; D005780:Gelatin