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Zirconia is commonly used for manufacturing of dental implants thanks to its excellent mechanical, biological and aesthetic properties. However, its bioinertness inhibits bonding with the surrounding hard tissue and other surface interactions. In our study, we present a method for multifunctionalization of zirconia surface to improve its osseointegration and to minimize the infection risks. For this reason, we introduced antibacterial and bioactive properties to zirconia surfaces by calcium phosphate biomimetic coating. The samples were incubated in vials in horizontal and vertical position in concentrated simulated body fluid (SBF) containing 0.1, 0.5, and 3 g/L of silver nanoparticles (Ag-NPs) and then were tested for their structure, surface properties, cytocompatibility and antibacterial properties. The results demonstrated that our method is suitable to introduce Ag-NPs at different concentrations into the calcium phosphate layer, i.e. from 0.05–26.6 atom% as shown by EDX. According to the results of CFU-assay these coatings exhibited antibacterial properties against S. aureus and E. coli in correlation with the concentration of Ag-NP. The potential cytotoxicity of the coated samples was determined by AlamarBlue® assay and live/dead staining of MG63 osteoblast-like cells in direct contact and by testing the extracts from the materials. Only samples containing 0.05 atom% Ag-NPs, i.e. incubated in vertical position at SBF with 0.01 g/L Ag-NPs, were found cytocompatible in direct contact with MG63 cells. On the contrary in the indirect tests, the extracts from all the materials were found cytocompatible. This method could allow developing the completely new material group, exhibiting not only one but several biological properties, which can improve osseointegration and minimize infection risks. [ABSTRACT FROM AUTHOR]

[Display omitted] • GO can functionalize inert zirconia surfaces by covalent immobilization. • GO nanofilm provides wettability and osteogenic character to zirconia implants. • GO coating on bioinert ceramics improves osteogenic differentiation of MSC. • Novel GO-film is full-covering, homogeneous, hydrophilic, and hydrolytically stable. This study aimed to join the proven osteogenic properties of graphene oxide (GO) with bioinert zirconia implants. The dip-coating technique allows achieving this goal by forming a thin, homogenous, hydrolytically, and mechanically stable GO film onto silanized ceramic-substrates. SEM, AFM, XPS, and contact angle measurements confirmed the presence, transparency, integrity, and homogenous covering character of the GO film. The GO film is hydrolytically stable since it remained intact after a soaking period of 24 days in double-distilled water (ddH 2 O) and phosphate buffered saline and resisted a ten-minute sonication treatment for in ddH 2 O. This strong hydrolytic stability is due to the silanization with 3-amino-propyl-diisopropylethoxy-silane (APDS) enhancing the anchoring of GO flakes onto zirconia surfaces. Besides, the GO film disinfectable in 70% ethanol. Subsequently, we assessed our immobilized GO film as cytocompatible for L929 mouse fibroblast and human mesenchymal stem cells and propitious for the osteogenic differentiation demonstrated by a two times upregulation of the osteogenic transcription factor RunX2. The active hydroxyl and carboxyl groups of the GO film open new perspectives for the functionalization of ceramic implants by immobilization of biological agents, such as growth factors or antibiotics, and thus enhance the osseointegration. [ABSTRACT FROM AUTHOR]