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.

Towards understanding of nanoparticle–protein corona

“…These factors may synergistically influence the recognition and uptake by cells (Babič et al 2009;Lunov et al 2011;Mok et al 2008;Shang et al 2014;Yang et al 2011). For example, when nanoparticles are incubated in a serum-free medium (e.g., HBSS), the uptake mechanism is clathrin-mediated endocytosis for COOHgrafted polystyrene (PS-COOH) nanoparticles and macropinocytosis for NH 2 -grafted PS, respectively.…”

“…However, their uptake mechanism is shifted to phagocytosis after incubated in serum-contained medium (Lunov et al 2011). Separately, surface coating of iron oxide nanoparticles with covalently attached highly specific biomolecules can enhance cellular uptake of nanoparticles (Babič et al 2009). By determining the dissociation constant (K d ) of Herceptin-modified gold nanoparticle (GNP) with ErbB2 receptors, the effect of nanoparticle sizes on the protein binding and resulting activation of receptors on membrane and subsequent protein expression were investigated (Fig.…”

Layer-by-layer engineered nanocapsules of curcumin with improved cell activity

“…According to DLS measurement, average diameter of CaCO3 NPs coated with (PDADMAC/PSS)5 films and hollow nanocapsules in water was 435.0±7.4 nm and 619.5±11.9 nm respectively, which are larger than those obtained from TEM measurement. This difference can be attributed to hydrodynamic swelling in aqueous media, and this discrepancy in particle diameter measured by DLS and TEM has been frequently observed when a nanoparticle surface is coated with a hydrophilic moiety (Babic et al, 2009). However, it should be noted that larger hollow nanocapsules (830.2±41.8 nm) was obtained when redispersed in cell media, probably due to aggregation in a presence of serum and sugar.…”

The use of dopamine-hyaluronate associate-coated maghemite nanoparticles to label cells

“…These results are comparable with those from previous studies. 30 When labeling chondrocytes, differences in growth and viability between labeled and unlabeled cells were not observed.…”