Zirconia Nanotubes as a Potential Coating on Implant Systems for Controlled Drug Release and Bioactivity

Implant-associated infections and insufficient tissue integration remain central challenges in the development of multifunctional biomaterials. These challenges have driven the need for modern implant systems to evolve from initially bioinert devices into regenerative tools for tissue engineering.
It is well established that the implant surface plays a critical role in addressing these challenges. Consequently, significant research efforts have been directed toward optimizing implant surfaces to improve biological performance. The use of nanostructured metal oxides as coatings on implant surfaces has attracted considerable interest in this regard. Increasing evidence suggests that such nanotopographies can enhance cellular responses and act as reservoirs for controlled drug release.
This thesis aims to develop and investigate zirconia nanotubes (ZrNTs) based surface coatings as multifunctional implant interfaces, with a focus on controlled drug delivery, antibacterial functionality, and host cell response interactions.
ZrNTs with designed morphologies were fabricated via electrochemical anodization by systematically varying anodization parameters. Several simple yet novel structural and chemical modifications were made to the fabricated ZrNT to improve drug-delivery performance, antibacterial properties, and cell-interaction behavior. Structural and chemical characterization was performed using mainly scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and time of flight secondary ion mass spectrometry (ToF-SIMS).
The main results of this dissertation include ZrNT with a modulated diameter (i.e., a bottleneck-like structure), which was successfully developed to mitigate initial burst drug release and enable an extended-release profile. Incorporation of silver nanoparticles via straightforward anodization of Zr-Ag alloys resulted in ZrNTs with broad–spectrum antibacterial activity. Protein adsorption studies revealed that surface chemistry (specifically, functionalization with hydroxyapatite) and morphology influence protein orientation and denaturation, which, in turn, affect cell–surface interactions.
The findings of this thesis demonstrate novel, simple, yet effective approaches toward optimizing the interface between the implant surface and the host environment to meet the critical requirements of biocompatibility and antibacterial properties. This work contributes to the design of smart, multifunctional biomaterials for improved implant performance. It introduces the potential of zirconia nanotubes as a versatile, tunable coating for bioactive, controlled drug-releasing implant surfaces.