Enhanced Tribological and Bacterial Resistance of Carbon Nanotube with Ceria- and Silver-Incorporated Hydroxyapatite Biocoating.

Pertaining to real-life applications (by scaling up) of hydroxyapatite (HA)-based materials, herein is a study illustrating the role of carbon nanotube (CNT) reinforcement with ceria (CeO₂) and silver (Ag) in HA on titanium alloy (TiAl6V4) substrate, utilizing the plasma-spraying processing technique, is presented. When compared with pure HA coating enhanced hardness (from 2.5 to 5.8 GPa), elastic modulus (from 110 to 171 GPa), and fracture toughness (from 0.7 to 2.2 MPa·m1/2) elicited a reduced wear rate from 55.3 × 10-5 mm³·N-1·m-1 to 2.1 × 10-5 mm³·N-1·m-1 in HA-CNT-CeO₂-Ag. Besides, an order of magnitude lower Archard's wear constant and a 41% decreased shear stress by for HA-CNT-CeO₂-Ag coating depicted the effect of higher hardness and modulus of a material to control its wear phenomenon. Antibacterial property of 46% (bactericidal) is ascribed to Ag in addition to CNT-CeO₂ in HA. Nonetheless, the composite coating also portrayed exaggerated L929 fibroblast cell growth (4.8 times more than HA), which was visualized as flat and elongated cells with multiple filopodial protrusions. Hence, synthesis of a material with enhanced mechanical integrity resulting in tribological resistance and cytocompatible efficacy was achieved, thereupon making HA-CNT-CeO₂-Ag a scalable potent material for real-life load-bearing implantable bio-coating.