Nanostructured titanium dioxide has been used in several studies as a surface modifier because it presents high hardness, increased dielectric constant and great chemical stability [1,2]. Furthermore, the surface modification with nanostructured TiO2 can improve in the biocorrosion resistance and increase the oxide bioactivity, presenting promising results in the interaction with the tissue, since the biocompatibility is determined by chemical processes that occur at the interface between the implant and the proteins of the biological fluids .
Chemically, the oxide surface is mainly terminated by -OH groups which can be functionalized by various biofunctional molecules, such as carboxylic acids, and other derivatives like esters, acid chlorides, carboxylate salts, and others forming self-assembled monolayers (SAMs) on the oxide surface . SAMs have well-defined surface properties, such as uniformity, stability and reproducibility. Hence, this chemical functionalization with appropriate physical changes in the material surface can enhance the interaction between the oxide and the biological environment .
In this work, anatase and rutile TiO2 films were grown by reactive sputtering on commercially pure (grade IV) titanium substrates. In the process, argon, oxygen and titanium, all grade VI, were used as working gases and sputtering target, respectively. The film structure was checked using X-ray diffraction. The surfaces of both anatase and rutile the films were functionalized with
3-mercaptopropionic acid (MPA) solution, in a concentration of 3 mM at a pH of 3.0, by immersion for 1 hour. After immersion, the samples were washed with Mili-Q water in order to remove non-adsorbed molecules. X-ray photoelectron analysis indicated the presence of hydroxyl groups for both pristine TiO2 anatase and rutile surfaces. For the rutile phase, it was possible to see a contribution of sulfur attached to oxygen. Interestingly, no contribution of sulfur at all was detected for anatase phase. Further investigations are being performed in order to understand the interactions between rutile and anatase TiO2 surfaces and the functional groups of MPA.
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