A biocompatible SiO2/ZnO coating with enhanced antibiofilm properties for dental applications

Due to its unique properties, yttrium-stabilized tetragonal zirconia (Y-TZP) is well-known as a high-performance material in dental medicine. However, some issues are still open: the interaction of the implant materials with surrounding tissues (osseointegration), the coupling with different biomaterials in the final device assembly (e.g. metal-ceramic dental restorations), and the ability to control bacterial colonization. Herein, we were focused on developing SiO2/ZnO layers deposited by a co-sputtering technique on Y-TZP substrate and investigating the antifouling effects of the layer. The morphological and chemical characterization of the samples was performed using conventional characterization techniques including FESEM, EDS, XPS, FTIR, water contact angle, and release tests. The hardness of the samples was investigated using the nanoindentation test. The results confirmed the successful deposition of the SiO2/ZnO layer on the surface of Y-TZP and an increase in the hardness (19 %) of the SiO2-coated sample by introducing ZnO. The cytocompatibility of the coating was investigated on adipose-derived mesenchymal stem cells (ASCs) evidencing that the developed coating has basic requirements for biological and dentistry applications due to its cytocompatibility. The antibacterial effect of the coating on Y-TZP was investigated against an oral bacterial strain of Enterococcus faecalis of clinical interest, used as a model organism with a significant positive outcome (∼70 % of bacteria biofilm reduction).