Effect of Albumin and Fibrinogen on Calcium Phosphate Formation on Sol−Gel-Derived Titania Coatings in Vitro

Abstract

The sol-gel technique provides a method to produce porous titania (TiO 2 ) coatings, which are known to induce bone-like hydroxyapatite formation on their surface in vitro. In this study, the calcium phosphate formation (in vitro bioactivity) on a sol-gel-derived titania coating was investigated in vitro in a simulated body fluid in the presence and absence of albumin (BSA) and fibrinogen (Fib) in solution as well as the effect of surface immobilized proteins on the biomineralization process. The effect of proteins on calcium phosphate (CP) formation was followed by ion concentration analysis, XRD, SEM-EDX, and XPS. When BSA and Fib were present in solution, the CP layer growth kinetics were strongly retarded. It is suggested that the bone-like apatite formation on sol-gel-derived titania coatings occurs via continuous dissolution/reprecipitation processes, where the initially formed CP phase(s) recrystallizes into a more thermodynamically stable phase(s), as previously observed for other biomaterials. Inhomogeneous charging was observed in the XPS experiments, which could be used to distinguish between an amorphous CP layer and poorly crystalline CP regions.

Use of sol–gel‐derived titania coating for direct soft tissue attachment

“…Thus, the introduction of proteins into the inorganic media used to study CaP formation gives indirect information on the transformation mechanism of the initially formed CaP phase(s) to the resulting CaP phase(s). In a recent article, 20 it was suggested that the formation of bonelike apatite on sol-gel-derived titania coatings also occurs via the dissolution/reprecipitation mechanism. It was suggested that the presence of proteins (BSA and Fib) does not inhibit the CaP nucleation but rather inhibits the growth stage of the initially formed CaP to bonelike apatite.…”

“…The Ca/P ratio of the uncharged CaP was lower (Ͻ1) than that of the charged CaP (near 1.3), corresponding to amorphous and poorly crystalline CaP phases, respectively. 20 In SBF solutions (SBF ϩ BSA, SBF ϩ Fib, SBF ϩ Plasma, and BSA added after 2 days), in which calcium and phosphate concentrations did not decrease during the observation time of 2 weeks, the calculated Ca/P ratio was closer to 1, and no charging effect was observed, suggesting that amorphous CaP has formed.…”

Osteoblast adhesion and matrix mineralization on sol–gel-derived titanium oxide

“…The sol-gel technique is a wet chemical process used to produce metallic oxide glass, bioceramic and bioactive titania-like surfaces [28][29][30]. Sol-gel coatings have demonstrated good bioactivity due to abundant hydroxyl (OH) groups on the surface that promote nucleation of calcium apatite or formation of mineralized matrix by osteoblasts [31][32][33][34]. Thin film oxide coatings can also be prepared by a stepwise surface sol-gel process (SSP) [35].…”

Formation and Topotactical Orientation of Fibrinogen Nanofibrils on Graphite Nanostructures

“…[1,29] Although the formation and deposition of amyloid-like protein nanofibrils in the human body are generally not desired, protein nanofibrils can play a very important role in the field of tissue engineering, [30] and biomedicine. [31,32] The intrinsic characteristics of the fg such as self assembly, [33] promotion of cell adhesion and the dual role in calcium phosphate formation [34] give fg an important role in the field of biomaterials science, [35] as fg is a potential building block for preparation of advanced biomaterials. [1] Furthermore, some properties of the protein nanofibrils are useful for nanotechnology.…”