Enhanced osteoblastic cell response on zirconia by bio-inspired surface modification

Excellent esthetic properties and limited plaque adhesion make zirconia ceramics an ideal material for implants in the fields of dentistry and orthopedics. Unfortunately, the physicochemical stability of zirconia makes it difficult to improve biocompatibility through surface modification. The dopamine-derived residue, 3,4-dihydroxy-l-phenylalanine (l-DOPA), has been identified as an important molecule secreted by marine mussels for the formation of adhesive pads. This study coated zirconia with l-DOPA to improve the biocompatibility of ZrO₂. As confirmed by contact angle and X-ray photoelectron spectroscopy (XPS), the formation of l-DOPA film can be controlled by varying the process temperature. Results from scanning electron microscopy (SEM) and atomic force microscopy (AFM) show that the topography of the zirconia substrate was preserved after being coated with a film of l-DOPA. Specifically, the thickness of the coating and initial cell spreading ability were both enhanced by preparing samples at higher temperatures. l-DOPA coated zirconia demonstrated better cyto-compatibility than uncoated specimens, as indicated by cell responses such as cell spreading and proliferation. These preliminary results suggest that l-DOPA film could be used to improve the cyto-compatibility of zirconia and further has the potential to immobilize other biofunctional molecules in biomedical applications.