超親水性処理チタンへのケモカインCXCL12の吸着特性

抄録

The evaluation of specific binding characteristics for bone-associated cytokines, especially chemokines, on titanium (Ti) surfaces may serve to clarify the mechanism of osseointegration during wound healing in the early stage of implant placement. It was recently reported that CXCL12 (SDF-1 : Stromal cell-derived factor 1) - CXCR4 chemokine signaling is expressed during bone healing and osseointegration of implants, and these chemokines play a critical role in homing and migration of mesenchymal stem cells. Accordingly, the analysis of response and application of these chemokines against titanium implants are becoming increasingly important. This study evaluated the binding behavior of chemokine CXCL12 on surface-modified Ti with superhydrophilicity, because superhydrophilic surface modification is expected to enhance the adsorption of proteins to titanium. In addition, the mechanism of enhancing adsorption of CXCL12 is considered by the surface analysis.

Atmospheric-pressure plasma treatment (Ti-Plasma), ultraviolet treatment (Ti-UV) and sodium hydroxide treatment (Ti-NaOH) as a superhydrophilic treatment were performed on a titanium sensor that was designed for quartz crystal microbalance (QCM) apparatus. Untreated gold (Au-Air) and titanium sensor (Ti-Air) were used as controls. Surface topography, wettability and surface characteristics were evaluated. In addition, adsorption properties of CXCL12 were assessed using the QCM method.

Superhydrophilicity was confirmed for all treatment groups including Ti-Plasma, Ti-UV and Ti-NaOH. Surface analyses showed that oxide was hardly found on Au-Air, whereas both oxide and hydroxide were found on Ti-Air. Furthermore, an apparent decrease of carbon content and increase of hydroxide were found on the superhydrophilic treatment groups compared to Ti-Air. The specific binding of CXCL12 adsorption was increased on the superhydrophilic treatment groups compared with Ti-Air. Possible mechanisms of the increase of CXCL12 adsorption on the superhydrophilic surfaces were considered to be due to the increase in surface energy caused by removal of hydrocarbons and increase in hydrogen bonds by relating the hydroxide. These results suggested that the superhydrophilic modifications may enhance the adsorption of CXCL12 as well as the migration of mesenchymal stem cells to titanium implants in the bone marrow.