Enhanced cellular adhesion on titanium by silk functionalized with titanium binding and RGD peptides.

Soft tissue adhesion on titanium represents a challenge for implantable materials. In order to improve adhesion at the cell/material interface we used a new approach based on the molecular recognition of titanium by specific peptides. Silk fibroin protein was chemically grafted with titanium binding peptide (TiBP) to increase adsorption of these chimeric proteins to the metal surface. A quartz crystal microbalance was used to quantify the specific adsorption of TiBP-functionalized silk and an increase in protein deposition by more than 35% was demonstrated due to the presence of the binding peptide. A silk protein grafted with TiBP and fibronectin-derived arginine-glycine-aspartic acid (RGD) peptide was then prepared. The adherence of fibroblasts on the titanium surface modified with the multifunctional silk coating demonstrated an increase in the number of adhering cells by 60%. The improved adhesion was demonstrated by scanning electron microscopy and immunocytochemical staining of focal contact points. Chick embryo organotypic culture also revealed strong adhesion of endothelial cells expanding on the multifunctional silk peptide coating. These results demonstrated that silk functionalized with TiBP and RGD represents a promising approach to modify cell-biomaterial interfaces, opening new perspectives for implantable medical devices, especially when reendothelialization is required.