Studies on Cell Compatibility, Antibacterial Behavior, and Zeta Potential of Ag-Containing Polydopamine-Coated Bioactive Glass-Ceramic

Dopamine is a small molecule that mimics the adhesive component (L-DOPA) of marine mussels with a catecholamine structure. Dopamine can spontaneously polymerize to form polydopamine (PDA) in a mild basic environment. PDA binds, in principle, to all types of surfaces and offers a platform for post-modification of surfaces. In this work, a novel Ag-containing polydopamine coating has been developed for the functionalization of bioactive glass-ceramics. In order to study the interactions between the surface of uncoated and coated samples and the environment, we have measured the surface zeta potential. Results confirmed that PDA can interact with the substrate through different chemical groups. A strongly negative surface zeta potential was measured, which is desirable for biocompatibility. The dual function of the material, namely the capability to exhibit bioactive behavior while being antibacterial and not harmful to mammalian cells, was assessed. The biocompatibility of the samples with MG-63 (osteoblast-like) cells was determined, as well as the antibacterial behavior against Gram-positive Staphylococcus carnosus and Gram-negative Escherichia coli bacteria. During cell biology tests, uncoated and PDA-coated samples showed biocompatibility, while cell viability on Ag-containing PDA-coated samples was reduced. On the other hand, antibacterial tests confirmed the strong antimicrobial properties of Ag-containing PDA-coated samples, although tailoring of the silver release will be necessary to modulate the dual effect of PDA and silver.