Engineering bioactive MWCNT-reinforced hydroxyapatite coatings on Ti29Nb5Zr alloy by plasma electrolytic oxidation method: A comprehensive approach to dental implant surface optimization

Titanium-niobium-zirconium (TiNbZr) alloys represent a promising class of newly developed titanium-based biomaterials, engineered to exhibit superior properties for biomedical applications. This study investigates the influence of hydroxylated multi-walled carbon nanotubes (MWCNTs) on the surface properties of hydroxyapatite coatings prepared by the plasma electrolytic oxidation (PEO) method for implant applications. The optimal concentration of MWCNTs in the PEO coating was determined based on the superior surface, electrochemical, and biological properties obtained. The incorporation of MWCNTs led to an enhancement in surface roughness from R-a 0.06 +/- 0.02 to R-a 0.618 +/- 0.03 mu m, improved wettability with a decrease in contact angle from 63.03 degrees +/- 1.1-28.29 degrees +/- 0.07, and a reduction in elastic modulus from 77.20 +/- 2.26 GPa to 54.50 +/- 2.22 GPa. Furthermore, electrochemical corrosion resistance analysis revealed an increase in inner passivation resistance up to 2.24 x 10 x(7) Omega.cm(2) with the addition of MWCNTs. Antibacterial activity analysis demonstrated that the optimal concentration of MWCNTs resulted in a 3.1-fold and 2.7-fold reduction in E. coli and S. aureus bacteria, respectively, compared to uncoated samples. Cell viability against MC3T3-E1 cells showed a 25 % higher viability with MWCNTs than uncoated substrates.