X-ray Photoelectron Spectroscopic Studies of the Reactivity of Basic Terminal OH of Titanium towards Tresyl Chloride and Fibronectin

Abstract

The immobilization of cell-adhesive proteins onto titanium implant improves biological responses at the implant-tissue interface. The aim of this study is to investigate how the reaction temperature during tresylation andpretreatment of titanium surface with H 2 O 2 solution influences the reactivity of titanium basic terminal OH group towards 2,2,2-trifluoroethanesulfonyl chloride (tresyl chloride) and fibronectin. Three different titanium surfaces were prepared, i.e., mirror polished, and pretreated either with 0.1 M H 2 O 2 /phosphate-buffered saline (PBS) solution (H 2 O 2 /PBS) or with 0.1 M H 2 O 2 /0.1 M NaOH aqueous solution (H 2 O 2 /NaOH) after mirror polishing. The basic terminal OH groups of titanium were allowed to react with tresyl chloride at 37°C or 70°C for 2 days. The tresylated titanium disk was then immersed into a fibronectin/PBS solution. The reactivity of titanium basic terminal OH group towards tresyl chloride and fibronectin was evaluated by the measurement of X-ray photoelectron spectroscopy (XPS). The reaction of titanium basic terminal OH group towards tresyl chloride at 37°C proceeded more effectively than that at 70°C. The basic OH group on H 2 O 2 /PBS-pretreated titanium showed the highest reactivity towards tresyl chloride by evaluating the F1s intensities in XPS measurement. Fibronectin could easily attach the tresylated titanium, and the attached fibronectin remained after 60 min ultrasonic cleaning regardless the different surfaces. Therefore, we concluded that after pretreatment with 0.1 M H 2 O 2 /PBS, reaction of titanium with tresyl chloride should be performed at 37°C in order to get easy attachment of fibronectin on titanium surface.