Towards a New Bone Scaffold Material - Exploring Silicon Nanowires as a Biomimetic Environment for Osteoblastic Differentiation
Final Report Abstract
The goal of the present project was the development of a novel nanomaterial as scaffold material for bone tissue engineering. The material consisted of long and very thin silicon fibres that were interwoven in a tissue-like fashion. The material promised to be a suitable scaffolding material to assist bone cell differentiation and bone build-up, as its structure is similar to that of the extracellular matrix. Additionally, the material Si is slowly released into the surrounding environment. This, first, means that the material will eventually be completely degraded and, second, that during this process, silicate will be delivered to the surrounding cells and tissue. Silicate has long been known to be necessary and beneficial for bone cells and is currently implemented in Bioglass products. As these positive effects have been anticipated, the material was improved even further by rolling it up to mimic the hierarchical structure of bone. Additionally, this free-standing nanostructure was stabilised by “nano-welding” neighbouring fibres together. With the successful fabrication of this material, here called silicon nanowire fleeces, the material synthesis goal of the project was realised. When the reaction of the cells to the material was analysed, the material proofed to impair cell viability instead of aiding them in their activity. As silicon as the basic material is not known to be toxic for cells, the question why the cells were harmed on the silicon nanowire material but not on flat silicon samples was intriguing. To analyse the mechanisms by which the cells react and are harmed, a new collaboration was started with experts in the quantitative proteomics of cell death. By analysing the proteome of cells that were treated with cytotoxic drugs and comparing it to the proteome of cells that were with other, equally cytotoxic, drugs, they devised a method to shed light on the cell death mechanism. This principle was applied to the material and the data from this experiment is currently analysed. When the mechanism of interaction and cell death is known, it will greatly inform future material design. Certain structures may be harmful and should consequently be avoided for tissue engineering scaffolds, while on the other hand they may be exploited to act against cancer cells or bacteria.
Publications
- 2019; The electronic properties of silicon nanowires during their dissolution under simulated physiological conditions, Appl. Sci. 9, 804
A.M. Steinbach, T. Sandner, M. Nilsen, X. Hua, R. Sivakumar, D. Geiger, A. Moeinian and S. Strehle
(See online at https://doi.org/10.3390/app9040804)
