Mixed zirconia calcium phosphate coatings for zirconia dental implants: Tailoring coating stability and bioactivity potential

In this study a bioinspired approach to induce self-mineralisation of bone-like material on alumina surfaces is presented. The mineralising enzyme alkaline phosphatase (ALP) is covalently immobilised by a carbodiimide-mediated chemoligation method. The enzymatic activity of immobilised ALP and its mineralisation capability are investigated at acellular conditions as well as in the presence of human bone cells. Analytical, biochemical, immunohistochemical characterisation show that ALP is efficiently immobilised, retains its activity and can trigger calcium phosphate mineralisation on alumina at acellular conditions. In vitro cell tests demonstrate that ALP-functionalised alumina clearly boosts and enhances bone cell mineralisation. Our results underpin the high potential of ALP-functionalised alumina for the development of bioactive surfaces for applications such as orthopaedic and dental implants, enabling potentially a fast and firm implant osseointegration.