Adsorption of proteins on nanoporous Ti surfaces

The cascade of events that regulate cell-substrate interactions is not yet fully understood. However, it is now generally recognized that proteins adsorbed on a substrate prior to its colonization have a major influence on initiating and directing cellular activities. Protein adsorption and the characteristics of the adsorbed layer are determined in part by the physical/chemical properties of the underlying surface. Chemical oxidation can be used to generate nanoscale textures on various metals used as implants in medicine. In this study, we exploit a mixture of H2SO4/H2O2 to etch sputtered titanium, and we evaluate the adsorption of a broad range of proteins on the resulting nanoporous surface. Untreated and nanoporous surfaces were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier-transform infrared spectroscopy (FTIR). Protein adsorption was assessed by using a quartz crystal microbalance in conjunction with dissipation monitoring (QCM-D). Our results demonstrate that the network of nanometric pits resulting from controlled chemical oxidation confers to titanium the capacity to differentially regulate protein adsorption. The observed selectivity in adsorption may have a significant impact on initial molecular events that ultimately dictate cell fate and activity.