Nano-size protein at the surface of a Ti–Zr–Ni quasi-crystalline alloy: Fibronectin adsorption on metallic nano-composites

•Fibronectin was adsorbed on Ti45Zr38Ni17 and compared to cp Ti.•Fibronectin surface saturation is reached for Fn solution concentrations greater than 150 μg ml−1.•The equivalent protein thickness is about 1 monolayer (6 nm) for Ti45Zr38Ni17 and cp Ti.•Preferential oxidation of Zr and Ti leads to their segregation in an outer mixed ZrO2/TiO2 oxide layer.

Surface characterisation of alloys before and after their interaction with proteins allows a more rational design of biomaterials. In this work, fibronectin adsorption on a Ti-based quasicrystals-forming alloy was studied by X-ray photoelectron spectroscopy (XPS) and compared to those obtained on pure titanium substrates (cp Ti). Different fibronectin (Fn) solution concentrations were tested in interaction with the quasi-crystalline/amorphous Ti45Zr38Ni17 composite. N 1s, C 1s, Ti 2p, Zr 3d and Ni 2p core level spectra were systematically recorded. The results indicate that fibronectin is chemically adsorbed on Ti45Zr38Ni17 as well as on cp Ti. The alloy surface composition and oxide thickness are not significantly changed in presence of the adsorbed protein. Data on the elemental distribution in the alloy surface obtained by XPS were completed by depth profiling with Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Surface saturation is clearly reached for Fn solution concentrations of 100–150 μg mL−1 for both surfaces. On the plateau, the equivalent protein thickness is 6 nm for Ti45Zr38Ni17 and 8 nm for cp Ti, both corresponding to one fibronectin monolayer. These results are in accordance with previous observations on osteoblasts adhesion, confirming the biocompatibility of Ti45Zr38Ni17. However, quasicrystals do not seem to influence the alloy surface reactivity.

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