Interaction of differently functionalized fluorescent silica nanoparticles with neural stem- and tissue-type cells

Abstract

Engineered amorphous silica nanoparticles (SiO₂ NPs), due to simple and low cost production, are increasingly used in commercial products and produced on an industrial scale. Despite the potential benefits, there is a concern that exposure to certain types of SiO₂ NPs may lead to adverse health effects. As some NPs can cross the blood--brain barrier and may, in addition, reach the central nervous system through the nasal epithelium, this study addresses the responses of different neural tissue-type cells including neural stem cells, neurons, astrocytes and microglia cells to increasing doses of 50 nm fluorescent core/shell SiO₂ NPs with different [–NH₂, –SH and polyvinylpyrrolidone (PVP)] surface chemistry. The SiO₂ NPs are characterized using a variety of physicochemical methods. Assays of cytotoxicity and cellular metabolism indicates that SiO₂ NPs cause cell death only at high particle doses, except PVP-coated SiO₂ NPs which do not harm cells even at very high concentrations. All SiO₂ NPs, except those coated with PVP, form large agglomerates in physiological solutions and adsorb a variety of proteins. Except PVP-NPs, all SiO₂ NPs adhere strongly to cell surfaces, but internalization differs depending on neural cell type. Neural stem cells and astrocytes internalize plain SiO₂, SiO₂–NH₂ and SiO₂–SH NPs, while neurons do not take up any NPs. The data indicates that the PVP coat, by lowering the particle–biomolecular component interactions, reduces the biological effects of SiO₂ NPs on the investigated neural cells.

• Fluorescence spectrum analysis
• neural cell types
• silica NP
• toxicity
• uptake

Acknowledgements

The authors wish to thank the Nikon Microscopy Center at IEM, Nikon Austria GmbH and Auro-Science Consulting Ltd for kindly providing microscopy support, and Dr. Matthew Boyles for helpful comments and suggestions.

Declaration of interest

The authors report no conflict of interest. The authors alone are responsible for the content and writing of this article. This study was supported by the EU seventh framework program, Marie Curie Actions, Network for Initial Training NanoTOES (PITN-GA-2010-264506), www.nanotoes.eu.

Supplementary material available online

Supplementary Figures S1–S8