Cytotoxicity and intracellular dissolution of nickel nanowires

Abstract

The assessment of cytotoxicity of nanostructures is a fundamental step for their development as biomedical tools. As widely used nanostructures, nickel nanowires (Ni NWs) seem promising candidates for such applications. In this work, Ni NWs were synthesized and then characterized using vibrating sample magnetometry, energy dispersive X-Ray analysis, and electron microscopy. After exposure to the NWs, cytotoxicity was evaluated in terms of cell viability, cell membrane damage, and induced apoptosis/necrosis on the model human cell line HCT 116. The influence of NW to cell ratio (10:1 to 1000:1) and exposure times up to 72 hours was analyzed for Ni NWs of 5.4 μm in length, as well as for Ni ions. The results show that cytotoxicity markedly increases past 24 hours of incubation. Cellular uptake of NWs takes place through the phagocytosis pathway, with a fraction of the dose of NWs dissolved inside the cells. Cell death results from a combination of apoptosis and necrosis, where the latter is the outcome of the secondary necrosis pathway. The cytotoxicity of Ni ions and Ni NWs dissolution studies suggest a synergistic toxicity between NW aspect ratio and dissolved Ni, with the cytotoxic effects markedly increasing after 24 hours of incubation.

• Magnetic nanowires
• nanomedicine
• nanoparticles
• nanotoxicology
• particle charactarization

Acknowledgements

The research reported in this publication was supported by the King Abdullah University of Science and Technology (KAUST) and by its Academic Excellence Alliance (AEA) and Academic Partnership Program (APP). JEP would like to thank Tahir Yapici and Bashir Warsama for their extensive help and observations regarding the experimental ICP-MS work. AEP also acknowledges an ERC starting investigator grant #257182 and an Elsie Widdowson Fellowship from Imperial College London. Figures 2(A) and 3(A), as well as their corresponding discussion, have been adapted from an earlier version of this work presented at the 2013 International Conference on Biological, Medical and Chemical Engineering and published by DEStech Publications, Inc.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Supplementary material available online

Supplementary Tables S1–S2 and Figures S1–S6