Increasing use of Ti-based blood-interfacing medical devices, along with the rising incidence of postimplant infections and thrombosis, necessitates the development of hemophobic surfaces that reduce thrombosis while offering enhanced antibacterial activity and low protein adsorption. Herein, this study aims to develop a carbon nanofiber-coated Ti6Al4V surface utilizing metal catalysts Ti, Cu, Ag, and Zn. CNF grown with Ag, Ti, Zn, and Cu catalysts resulted in a high degree of graphitization (ID/IG), i.e., 0.71, 0.67, 0.63, and 0.58, which is attributed to their associated sp2 hybridization resulting strong water and blood repellence (contact angles >129°). Ti-CNF, Cu-CNF, Ag-CNF, and Zn-CNF showed higher release of their respective ions (83, 94, 96, and 92 ppb, respectively) compared to uncoated Ti6Al4V (26 ppb), due to sputtering of the metal catalysts. Ti-CNF, Cu-CNF, Ag-CNF, and Zn-CNF exhibited increased contact angles of 135°, 148°, 129°, and 144°, respectively, relative to uncoated Ti6Al4V, indicating enhanced surface hydrophobicity, attributed to air pocket formation. Despite comparable ion release among the coatings, Ag-CNF and Zn-CNF exhibited the highest antibacterial activity against E. coli (40 and 44%) and S. aureus (27 and 38%), respectively, which is attributed to the strong intrinsic antimicrobial effects of Ag+ and Zn2+ ions. Additionally, surface characteristics played an important role: the reduced contact angle of Ag-CNF promotes greater bacterial interaction and ion-mediated cell damage, while an increased hydrophobicity of Cu-CNF and Zn-CNF also contributed to their antibacterial activity by limiting bacterial adhesion and survival compared to Ti-CNF. Furthermore, the CNF-coated surfaces showed reduced protein adsorption and lower hemolysis, indicating improved hemocompatibility. Zn-CNF exhibited the highest cell density, showing a 4-fold (507 cell/mm2) increase compared to that of uncoated Ti6Al4V. Importantly, none of the CNF-coated surfaces exhibited cytotoxic effects. CNF-grown Ti6Al4V surfaces with selected catalysts produced multifunctional coatings with enhanced antibacterial performance and blood compatibility, highlighting their potential for blood interface medical devices.
Singh et al. (Tue,) studied this question.