Rapid mussel-inspired synthesis of PDA-Zn-Ag nanofilms on TiO 2 nanotubes for optimizing the antibacterial activity and biocompatibility by doping polydopamine with zinc at a higher temperature.

Mussel-inspired deposition of polydopamine (PDA) is a green chemical method that has been used to load silver nanoparticles on titanium oxide nanotubes (TiO2 NTs) to kill bacteria. However, a long reaction time is required for both the polymerization of dopamine and the reaction between PDA and silver nitrate. In addition, the deposition of silver nanoparticles is difficult to control, which may increase the risk of cytotoxicity. In this study, a rapid polymerization of dopamine was achieved by performing the reaction in a water bath at 90 °C (PDA-H). Furthermore, the reduction of Ag+ ions was markedly accelerated by the PDA-Zn film that was formed on the surface of TiO2 NTs from a solution of dopamine and zinc nitrate under the same heating conditions. The reaction between the PDA-Zn film and silver nitrate was dramatically reduced to 10 min, and the silver nanoparticles deposited on the PDA-Zn film were more uniform than those by PDA-H film. This PDA-Zn-Ag-TiO2 NTs material exhibited good antibacterial activity, as evidenced by the inhibition zone. The WST-1 assay indicated that the PDA-Zn-Ag film possessed a lower cell cytotoxicity and better biocompatibility than other Ag containing PDA films.