*Article* **Comprehensive Evaluation of the Biological Properties of Surface-Modified Titanium Alloy Implants**

**Piotr Piszczek 1,2,\*, Aleksandra Radtke 1,2,\*, Michalina Ehlert 1,2, Tomasz J ˛edrzejewski 3, Alicja Sznarkowska 4, Beata Sadowska 5, Michał Bartma ´nski 6, Ya¸sar Kemal Erdo ˘gan 7, Batur Ercan 7,8,9 and Waldemar J ˛edrzejczyk 2**


Received: 13 December 2019; Accepted: 22 January 2020; Published: 25 January 2020

**Abstract:** An increasing interest in the fabrication of implants made of titanium and its alloys results from their capacity to be integrated into the bone system. This integration is facilitated by different modifications of the implant surface. Here, we assessed the bioactivity of amorphous titania nanoporous and nanotubular coatings (TNTs), produced by electrochemical oxidation of Ti6Al4V orthopedic implants' surface. The chemical composition and microstructure of TNT layers was analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). To increase their antimicrobial activity, TNT coatings were enriched with silver nanoparticles (AgNPs) with the chemical vapor deposition (CVD) method and tested against various bacterial and fungal strains for their ability to form a biofilm. The biointegrity and anti-inflammatory properties of these layers were assessed with the use of fibroblast, osteoblast, and macrophage cell lines. To assess and exclude potential genotoxicity issues of the fabricated systems, a mutation reversal test was performed (Ames Assay MPF, OECD TG 471), showing that none of the TNT coatings released mutagenic substances in long-term incubation experiments. The thorough analysis performed in this study indicates that the TNT5 and TNT5/AgNPs coatings (TNT5—the layer obtained upon applying a 5 V potential) present the most suitable physicochemical and biological properties for their potential use in the fabrication of implants for orthopedics. For this reason, their mechanical properties were measured to obtain full system characteristics.

**Keywords:** Ti6Al4V implants; anodization process; XPS; antimicrobial activity; genotoxicity assessment; anti-inflammatory properties; mechanical properties
