Adsorption Characteristics of Fibronectin and CXCL12 Onto Super-hydrophilic Titanium

Objectives: The specific binding characteristics for cell adhesion protein and bone-associated cytokine on the titanium surfaces may serve to clarify the mechanism of osseointegration in the early stage of implant placement. In addition to cell adhesion protein, it is recently reported that CXCL12 chemokines play a critical role in homing and migration of mesenchymal stem cells. Accordingly, the adsorption characteristics of these proteins against titanium implants are getting important for enhancing the osseointegration capability. This study aimed to investigate the binding behavior of these proteins on the super-hydrophilic titanium, and enhancing mechanism of protein adsorption using surface analyses.
Methods: The atmospheric-pressure plasma treatment (Ti-Plasma)，ultraviolet treatment (Ti-UV) and sodium hydroxide treatment (Ti-NaOH) as a super-hydrophilic treatment were performed to the titanium sensor that was designed for quartz crystal microbalance (QCM) apparatus. Untreated titanium sensor (Ti-Air) was used as a control. Surface topography, wettability and surface characteristics were evaluated. Adsorption properties of fibronectin and CXCL12 were assessed using a QCM method.
Results: Super-hydrophilicity was confirmed on all treatment groups. Apparent decrease of carbon content and increase of hydroxide were shown on the super-hydrophilic treatment groups. The specific bindings of fibronectin and CXCL12 adsorption increased on the super-hydrophilic treatment groups compared with Ti-Air. Possible mechanisms of increasing adsorption of these proteins on the super-hydrophilic surfaces were consider due to increasing the surface energy caused by removal of hydrocarbon and increasing hydrogen bond relating with hydroxide.
Conclusions: These results suggested that the super-hydrophilic modifications are promising method for enhancing adsorption of fibronectin and CXCL12, expecting that migration of mesenchymal stem cells to titanium implants and facilitating the osseointegration in the early stage of implant placement.