Hoskins, C, Cuschieri, A and Wang, L (2012) The cytotoxicity of polycationic iron oxide nanoparticles: Common endpoint assays and alternative approaches for improved understanding of cellular response mechanism. Journal of Nanobiotechnology, 10 (15). ISSN 1477-3155

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Background: Iron oxide magnetic nanoparticles (MNP’s) have an increasing number of biomedical applications. As
such in vitro characterisation is essential to ensure the bio-safety of these particles. Little is known on the cellular interaction or effect on membrane integrity upon exposure to these MNPs. Here we synthesised Fe3O4 and surface coated with poly(ethylenimine) (PEI) and poly(ethylene glycol) (PEG) to achieve particles of varying surface positive charges and used them as model MNP’s to evaluate the relative utility and limitations of cellular assays commonly applied for nanotoxicity assessment. An alternative approach, atomic force microscopy (AFM), was explored for the analysis of membrane structure and cell morphology upon interacting with the MNPs. The particles were tested in vitro on human SH-SY5Y, MCF-7 and U937 cell lines for reactive oxygen species (ROS) production and lipid peroxidation (LPO), LDH leakage and their overall cytotoxic effect. These results were compared with AFM topography imaging carried out on fixed cell lines.

Results: Successful particle synthesis and coating were characterised using FTIR, PCS, TEM and ICP. The particle size
from TEM was 30 nm (−16.9 mV) which increased to 40 nm (+55.6 mV) upon coating with PEI and subsequently
50 nm (+31.2 mV) with PEG coating. Both particles showed excellent stability not only at neutral pH but also in
acidic environment of pH 4.6 in the presence of sodium citrate. The higher surface charge MNP-PEI resulted in
increased cytotoxic effect and ROS production on all cell lines compared with the MNP-PEI-PEG. In general the
effect on the cell membrane integrity was observed only in SH-SY5Y and MCF-7 cells by MNP-PEI determined by
LDH leakage and LPO production. AFM topography images showed consistently that both the highly charged
MNP-PEI and the less charged MNP-PEI-PEG caused cell morphology changes possibly due to membrane
disruption and cytoskeleton remodelling.

Conclusions: Our findings indicate that common in vitro cell endpoint assays do not give detailed and complete
information on cellular state and it is essential to explore novel approaches and carry out more in-depth studies to
elucidate cellular response mechanism to magnetic nanoparticles.

Item Type: Article
Additional Information: This is the final published version of the article (version of record). It first appeared online via [insert publisher name] at BioMed Central at http://dx.doi.org/10.1186/1477-3155-10-15 - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: magnetic nanoparticle, cellular interaction, cell membrane, cytotoxicity, cell viability assay, atomic force microscopy, zeta potential
Subjects: Q Science > Q Science (General)
R Medicine > R Medicine (General)
Divisions: Faculty of Medicine and Health Sciences > Institute for Science and Technology in Medicine
Depositing User: Symplectic
Date Deposited: 01 Sep 2016 13:45
Last Modified: 22 Aug 2018 08:56
URI: https://eprints.keele.ac.uk/id/eprint/2149

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