Graphene-based antibacterial composite coatings electrodeposited on titanium for biomedical applications

• Novel graphene based composite coating on titanium obtained by electrophoretic deposition.
• Homogenous, non-toxic Ag/HAP/Gr coating with improved mechanical properties.
• New apatite layer formation in SBF has proved the coating bioactivity.
• Diminished bacterial growth of S. aureus and E. coli after only 3 h of exposure.

The graphene based silver/hydroxyapatite/graphene (Ag/HAP/Gr) composite coatings were produced by electrophoretic deposition (EPD) on titanium to assemble porous bioactive homogenous coatings, with improved corrosion stability in simulated body fluid (SBF). Novel composite coatings were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), Raman spectroscopy, X-ray photoelectron analysis (XPS) and electrochemical impedance spectroscopy (EIS). The improved properties of graphene based coatings in respect to the graphene-free coatings, as a consequence of toughening action of graphene, were demonstrated: reduced surface cracks, better mechanical resistance (hardness and elastic modulus increased by 10%) and enhanced thermal stability, while the Ca/P ratio was closer to the stoichiometric value. The bioactivity of Ag/HAP/Gr composite coatings was proved by a newly formed apatite layer in SBF with enhanced corrosion stability, while antibacterial activity against Staphylococcus aureus and Escherichia coli and noncytotoxicity against healthy peripheral blood mononuclear cells (PBMC) indicate the high potential for biomedical applications.