Biomimetic synthesis of Ag, Zn or Co doped HA and coating of Ag, Zn or Co doped HA/fMWCNT composite on functionalized Ti

In this study a novel composite containing fMWCNT and Ag, Zn or Co doped hydroxyapatite (HA) and undoped HA successfully synthesized using biomimetic process and coated on the chemically silane functionalized Ti via facile surface functionalization and deposition approach through the covalent immobilization. In this approach, the properties of Ti pretreated with NaOH and APTES were examined before the composite coating. Functional groups with oxygen were created on the MWCNT surface by acidic treatment. The synthesized powders were characterized using SEM, XRD, EDS, TGA, FTIR, Raman. Surface energies were decreased from 46.03 mN/m (Ti) to 43,79 mN/m (Ti-/fMWCNT/Ag, Zn or Co doped HA). The contact angles of APTES,fMWCNT and undoped or doped HA containing Ti surfaces increased from 40.03 +/- 1.2 to 49.05 +/- 1.6 degrees. The bond strengths between the coatings and Ti substrates were measured using an adhesive strength test which indicates that the crosslinking process increased the adhesion strength (from 14.6 +/- 0.9 to 19.8 +/- 1.2 MPa). The results indicated that the Ag+, Zn2+ or Co2+ added in prepared SBF medium have been located in the HA lattice structure at rate of 1.06, 1.86 and 1.78 at.%, respectively. The biocompatibility of the synthesized composites was evaluated using MTT assays in vitro and no negative effect was observed on cell viability. This work shows that the fMWCNT/Ag, Zn or Co doped HA coating promise for the potential implementation in biomaterial coating fields.