Wang Daming, Poologasundarampillai Gowsihan, van den Bergh Wouter, Chater Richard J, Kasuga Toshihiro, Jones Julian R, McPhail David S
Department of Materials, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.
Biomed Mater. 2014 Feb;9(1):015013. doi: 10.1088/1748-6041/9/1/015013. Epub 2014 Jan 23.
Understanding the distribution of critical elements (e.g. silicon and calcium) within silica-based bone scaffolds synthesized by different methods is central to the optimization of these materials. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used to determine this information due to its very high surface sensitivity and its ability to map all the elements and compounds in the periodic table with high spatial resolution. The SIMS image data can also be combined with depth profiles to construct three-dimensional chemical maps. However, the scaffolds have interconnected pore networks, which are very challenging structures for the SIMS technique. To overcome this problem two experimental methodologies have been developed. The first method involved the use of the focused ion beam technique to obtain clear images of the regions of interest and subsequently mark them by introducing fiducial marks; the samples were then analysed using the ToF-SIMS technique to yield the chemical analyses of the regions of interest. The second method involved impregnating the pores using a suitable reagent so that a flat surface could be achieved, and this was followed by secondary ion mapping and 3D chemical imaging with ToF-SIMS. The samples used in this work were sol-gel 70S30C foam and electrospun fibres and calcium-containing silica/gelatin hybrid scaffolds. The results demonstrate the feasibility of both these experimental methodologies and indicate that these methods can provide an opportunity to compare various artificial bone scaffolds, which will be of help in improving scaffold synthesis and processing routes. The techniques are also transferable to many other types of porous material.
了解通过不同方法合成的二氧化硅基骨支架中关键元素（如硅和钙）的分布情况，对于优化这些材料至关重要。飞行时间二次离子质谱（ToF-SIMS）因其极高的表面灵敏度以及能够以高空间分辨率绘制元素周期表中的所有元素和化合物的能力，已被用于确定此类信息。SIMS图像数据还可与深度剖面相结合，以构建三维化学图谱。然而，这些支架具有相互连接的孔隙网络，这对SIMS技术而言是极具挑战性的结构。为克服这一问题，已开发出两种实验方法。第一种方法是使用聚焦离子束技术获取感兴趣区域的清晰图像，随后通过引入基准标记对其进行标记；然后使用ToF-SIMS技术对样品进行分析，以获得感兴趣区域的化学分析结果。第二种方法是使用合适的试剂浸渍孔隙，从而获得一个平整的表面，随后进行二次离子映射以及使用ToF-SIMS进行三维化学成像。本研究中使用的样品是溶胶-凝胶70S30C泡沫、电纺纤维以及含钙的二氧化硅/明胶混合支架。结果证明了这两种实验方法的可行性，并表明这些方法能够提供一个比较各种人工骨支架的机会，这将有助于改进支架的合成和加工路线。这些技术也可转移应用于许多其他类型的多孔材料。
