Fibronectin silanized titanium alloy: a bioinductive and durable coating to enhance fibroblast attachment in vitro

Long term success of percutaneous implants is dependent on soft tissue attachment to prevent infection and epithelial downgrowth, which leads to failure of the implant. Fibronectin coatings are known to enhance fibroblast attachment in vitro, but are subject to desorption from serum protein competition in vivo. This paper quantifies the binding of fibronectin to titanium alloy by silanization and the durability of this attachment when soaked in protein-rich fluid compared with adsorbed fibronectin. The biological activity of fibronectin bound to silanized titanium alloy was confirmed by analyzing cell area, morphology, immunolocalization of focal contacts, and metabolism of dermal fibroblasts. This was compared with both adsorbed fibronectin and uncoated titanium alloy. Silanized titanium alloy bound over twice the amount of fibronectin compared to untreated titanium alloy. On soaking in fetal calf serum there was no significant loss of fibronectin (p = 0.589) from the silanized surface but a significant 44% loss (p = 0.002) from untreated surfaces. Fibroblasts on silanized fibronectin had significantly larger cell areas and more vinculin focal contact markers when compared to untreated surfaces (p < 0.005). The results confirm the durability of silanized fibronectin from protein competition and bioactive effect on fibroblasts.