The design and fabrication of surfaces allowing the control of cell to material interactions is currently a subject of great significance, given its potential impact in the development of implantable medical devices and engineered tissues. Irradiation of materials with MeV ions has been used in the last decades to synthesize new materials and to induce luminescent or magnetic properties [1–3]. In particular, high-dose irradiation increases the resistivity of Si, inhibiting the formation of porous silicon (PS) during the subsequent anodization . In this way, if a high-energy focused ion beam is electromagnetically scanned, or a wide defocused beam is shone through the appropriate mask, bidimensional patterns can be defined in a controlled way .
Bone progenitor cells are within a bone microenvironment replete with growth factors, nutrient, morphologic factor, and mechanical environment in an adequate combination. Cellular developments, such as fate selection, proliferation, differentiation, migration, or apoptosis, are guided by multiple surface cues that are potentially remodeled during cell culture assays . Interactions between cells and the underlying surface control cellular attachment, proliferation, and activity . In fact, cells respond to synthetic topographic surfaces in many different ways, which depend upon many factors including feature size and geometry, cell type, or the physicochemical properties of the particular surface . In this regard, surface micropatterns have been demonstrated to be a useful tool for the control of cell behavior [8, 9]. Moreover, surface nanotopography has been shown to exert influence over cell adhesion, morphology, proliferation, migration, differentiation, alignment, cytoskeleton organization, and gene expression in many cell types, including human mesenchymal stem cells (hMSCs) ; hMSCs are being increasingly used in therapeutic applications for bone, cartilage, and fat transplantation and repair . However, success in the development of useful applications is currently limited due to the complexity of interactions that affect the differentiation and proliferation of stem cells. For many applications, a precise control of issues such as cell adhesion and migration is required. In this regard, it has been shown that mechanically induced focal adhesion amplifies anti-adipogenic pathways in mesenchymal stem cells .
Nanostructured PS can be described as a complex network of Si nanocrystals with large specific surface area . This material shows a wide variety of interesting properties leading to applications in several fields ranging from micro- and optoelectronics to biomedical applications . Regarding this particular area, it is important to note that the biocompatibility of PS strongly depends on its porosity and pore size and can be tailored as a function of the particular application [15–17]. Furthermore, PS presents reputed biocompatibility with epithelium , osteochondral , neuronal , and eye tissues , which opens the way for its use in tissue engineering applications.