Controlled cellular growth by superhydrophobic microstructured surfaces of implantable biodegradable polymer substrate

Biodegradable polymers with elastomeric properties have recently received attention for their potential use in the engineering of soft tissues such as blood vessel, heart valves, cartilage, tendon, and bladder, which exhibit elastic properties [1, 2]. In this paper, microfabrication technology has been applied successfully to biodegradable polymer films to encourage cell growth in designated area. This work is presented with the final goal of fabricating implantable polymer scaffolds to produce blood capillaries in controlled manner spatially by using the concept of superhydrophobic surfaces. There are several methods to control cell growth including patterned chemical cues on the surface. Although successful in patterned cell growth, chemical cues are not suitable for implantation. While the concept of "contact guidance" uses physical cues to guide cell growth [3-5], most of the research has been done on either conventional microelectronics material such as silicon and metals or non-implantable polymers such as PDMS. Besides the materials, the guiding microstructures were limited with mainly 2-D groove patterns. Adhesion and proliferation of cells are main keys for successful cell guidance, however, there are many factors affecting to cell adhesion and proliferation. Wettability of surface is one of the major factors and it is known that cell adhesion can be achieved most successfully in the contact angle window 50°-90°. In addition, it is well studied that surface roughness can alter surface wettability of chemically homogeneous surface [6, 7]. Figure 1 illustrates the roughness effect of surface wettability. So-called 'superhydrophobic' or 'superhydrophilic' surfaces can be achieved by introducing a micro-or nano-scale roughness to the surface. Thus, we have introduced microscale roughness to the biodegradable polymer film surface and achieved superhydrophobic surfaces where the cell adhesion is preferentially much lower than on smooth scaffold surfaces.