Collagen Coatings on Titanium: Comparative Study of Electrochemical and Chemical Formation

This study investigates the influence of two collagen coating formation approaches, self-assembly and electrochemical formation by cyclic voltammetry, on the surface properties and electrochemical behavior of titanium (Ti). Collagen-modified Ti surfaces were characterized before and after 7 days of immersion in Fusayama artificial saliva using attenuated total reflectance Fourier-transform infrared spectroscopy, field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, X-ray diffraction, and electrochemical impedance spectroscopy. Self-assembly produced a continuous collagen layer, whereas cyclic voltammetry generated a fibrillar coating. During immersion, calcium phosphate (CaP) deposits formed on both collagen-modified surfaces, but with distinctly different spatial organization. The self-assembled coating underwent reorganization, whereas the electrochemically formed coating retained its fibrillar framework closely associated with the CaP deposits. This organic–inorganic architecture was accompanied by enhanced electrochemical barrier properties after 7 days compared with the self-assembled coating. Density functional theory calculations further showed that one-electron oxidation of an adsorbed collagen-model tripeptide induces pronounced structural rearrangement, providing molecular-level insight into the redox response of collagen-derived species at the TiO2 interface. In addition, prolonged exposure of Ti surfaces to cell culture media resulted in negligible Ti release, while the resulting conditioned media did not reduce the metabolic viability of HGF-1 or MG-63 cells under the investigated conditions, supporting favorable indirect in vitro cytocompatibility.