Electropolymerization of functionalized barium titanate reinforced polypyrrole composite coatings on nitinol alloy for biomedical applications

In the current study, the nitinol alloy (NiTi) was electrochemically coated with conductive polypyrrole (PPy) and polypyrrole/polydopamine functionalized barium titanate nanoparticles (PBT). The composite coatings were attained by adding different concentrations of PBT nanoparticles (1–10 wt%) to the electrochemical deposition bath. The results of transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), dynamic laser scanning (DLS), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) confirmed the successful development of a polydopamine (PDA) layer on the surface of barium titanate nanoparticles (BT NPs) and their incorporation into PPy matrix composite coatings. The optimum concentration of PBT was beneficial for coating adhesion strength due to PDA bonding with PPy and metallic substrate via the catechol moieties. Electrochemical examinations demonstrated that PPy/5PBT coating revealed excellent corrosion protection in the Ringer medium. The PBT particles also reduced the overall conductivity of the PPy coating by about tenfold and significantly improved the mineralization of the composite coatings by providing favorable sites for Ca ion adsorption and subsequent hydroxyapatite (HA) formation reactions. The results of osteoblast cell attachment revealed that PBT had a promising effect on the cellular behavior of the composite-coated samples.