Protein immobilization on nanostructured surfaces with different wettability

Protein immobilization on solid surfaces is an important phenomenon in many biological processes. Unfortunately this phenomenon is not well understood so far as it is often complicated by the type of proteins involved in the process, surface topography, surface chemistry, and surface wettability. Here we engineer a series of nanostructured surfaces with similar surface topography and chemistry, but varied wettability ranging from superhydrophobicity to superhydrophilicity. The nanostructured surfaces have a microstructure of arrays of vertically aligned carbon nanotubes capped with amorphous carbon nanoparticles. The wettability is tuned through the shape of amorphous carbon nanoparticles. Bone morphogenetic protein-2 (BMP-2) is used as the prototype protein and the amount of immobilized BMP-2 is measured by enzyme-linked immunosorbent assay (ELISA). Our results show that the release of BMP-2 is closely related to the wettability of nanostructured surfaces.