Protein Adsorption as a Key Mediator in the Nanotopographical Control of Cell Behavior

Surface nanotopography is widely employed to control cell behavior and in particular controlled disorder has been shown to be important in cell differentiation/maturation. However, extracellular matrix proteins, such as fibronectin (FN), initially adsorbed on a biomaterial surface are known to mediate the interaction of synthetic materials with cells. In this work, we examine the effect of nanotopography on cell behavior through this adsorbed layer of adhesive proteins using a nanostructured polycarbonate surface comprising 150 nm-diameter pits originally defined using electron beam lithography. We address the effect of this nanopitted surface on FN adsorption and subsequently on cell morphology and behavior using C2C12 myoblasts. Wettability measurements and atomic force microscopy imaging showed that protein is adsorbed both within the interpits spaces and inside the nanopits. Cells responded to this coated nanotopography with the formation of fewer but larger focal adhesions and by mimicking the pit patterns within their cytoskeleton, nanoimprinting, ultimately achieving higher levels of myogenic differentiation compared to a flat control. Both focal adhesion assembly and nanoimprinting were found to be dependent on cell contractility and are adversely affected by the use of blebbistatin. Our results demonstrate the central role of the nanoscale protein interface in mediating cell-nanotopographical interactions and implicate this interface as helping control the mechanotransductive cascade.