Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland.
Biomaterials. 2012 Nov;33(32):8055-61. doi: 10.1016/j.biomaterials.2012.07.037. Epub 2012 Aug 3.
Surface gradients facilitate rapid, high-throughput, systematic investigations in cell biology, materials science, and other fields. An important surface parameter is the surface roughness on both the micrometer and nanometer scales in the lateral direction. Two approaches have been combined to create two-dimensional roughness gradients by adding a nanoparticle density gradient onto a gradient of micro-featured roughness. All fabricated gradients were extensively characterized by SEM, AFM and optical profilometry to ensure their quality and to determine the roughness parameter Ra along the gradient. Additionally, a Fourier-transform approach was applied that allows a wavelength-dependent analysis of the surface topography. Since cell-culture assays require replicate experiments, a replica technique was used to create copies of the master gradient. Creating a negative replica in an elastomeric material served as a mold for a subsequent ceramic-casting process. A positive replica was then formed from epoxy resin, which was subsequently coated with titanium and used for cell studies. Finally, these gradients were used in cell-culture assays to determine cellular response to surface roughness. The results clearly demonstrate the influence of surface roughness on the production by osteoblasts of markers for osteogenesis. It was shown that high roughness in the micrometer range, combined with an intermediate nanofeature density (30-40 features/μm2), leads to the highest degree of osteopontin production after 14 days.
表面梯度可以促进细胞生物学、材料科学等领域的快速、高通量、系统研究。一个重要的表面参数是横向方向上的微米和纳米尺度的表面粗糙度。通过在微特征粗糙度梯度上添加纳米颗粒密度梯度，已经结合了两种方法来创建二维粗糙度梯度。通过 SEM、AFM 和光学轮廓仪对所有制备的梯度进行了广泛的表征，以确保其质量，并确定沿梯度的粗糙度参数 Ra。此外，还应用了傅里叶变换方法，允许对表面形貌进行波长相关的分析。由于细胞培养实验需要重复实验，因此使用复制技术来创建主梯度的副本。在弹性体材料中制作负模，作为随后的陶瓷铸造过程的模具。然后用环氧树脂形成正模，随后涂钛并用于细胞研究。最后，这些梯度被用于细胞培养实验，以确定细胞对表面粗糙度的反应。结果清楚地表明，表面粗糙度对成骨细胞产生成骨标志物的影响。结果表明，在 14 天内，微米级的高粗糙度与中等纳米特征密度（30-40 个特征/μm2）相结合，导致骨桥蛋白的产生程度最高。
