TiO2 Nanotubes Functionalized with Icariin for an Attenuated In Vitro Immune Response and Improved In Vivo Osseointegration.

Due to their superior mechanical and chemical properties, titanium (Ti) and its alloys have been widely used as orthopedic implantable devices. However, their bioinertness represents a limitation, which can be overcome by employing various surface modifications, such as TiO2 nanotube (TNT) fabrication via electrochemical anodization. Anodic TNTs present tunable dimensions and unique structures, turning them into feasible drug delivery platforms. In the present work, TNTs were loaded with icariin (Ica) through an adhesive intermediate layer of polydopamine (DP), and their in vitro and in vivo biological performance was evaluated. The successful fabrication of the modified surfaces was verified by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and contact angle measurements (CA), while the in vitro release of Ica was evaluated via UV-VIS spectrophotometry. In terms of in vitro behaviour, comparative studies on RAW 264.7 macrophages demonstrated that the TNT substrates, especially TNT-DP-Ica, elicited a lower inflammatory response compared to the Ti support. Moreover, the in vivo implantation studies evinced generation of a reduced fibrotic capsule around this implant and increased thickness of the newly formed bone tissue at 1 month and 3 months post-implantation, respectively. Overall, our results indicate that the controlled release of Ica from TNT surfaces could result in an improved osseointegration process.

Nitrodopamine vs dopamine as an intermediate layer for bone regeneration applications.

The aim of this paper was to present a parallel investigation of the poly(dopamine) (DP) and nitrodopamine (NDP) structures deposited on titanium surface (Ti) and titanium oxide nanotubes (NT-TiO2/Ti) and to highlight their advantages and drawbacks to serve as an intermediary layer for bone regeneration applications. This study outlines some hypotheses regarding the manner in which these compounds are able to form a stable film that could serve as bioadhesive. The paper is also a study of structuring and evolution of film architecture for two coatings, polydopamine and nitrodopamine in terms of surface structure, stability, wettability, morphology, adhesion and ability to protect the titanium surface. All investigations are based on the data provided by surface characterization techniques: SEM, RAMAN, XRD, XPS, wettability and flexural strength. The impact of polydopamine and nitrodopamine coatings on the biocompatibility of titanium nanotubes was investigated in vitro. Cell morphology, viability, proliferation and pre-osteoblast differentiation were examined in detail. It was highlighted that both DP and NDP functionalized TiO2 nanotubes display good cell response in terms of cell spreading, formation of focal adhesions, cell viability and proliferation, suggesting their suitability for applications in bone regeneration field. However, NDP coated TiO2 nanotubes demonstrated an enhanced osteogenic potential compared to DP coated substrates.