One-step deposition of antibacterial Ag@Pdop hybrid films on an NiTi alloy

In this study, by one-step immersion, silver aggregates enwrapped in a polydopamine (Pdop) film (Ag@Pdop hybrid film) were deposited onto a nickel–titanium (NiTi) surface. The Ag aggregates in the Ag@Pdop hybrid films were formed through burst formation, following the Ostwald ripening and oriented attachment of Ag nanoparticles (NPs). As the coating time was increased, thickening of the Pdop film covered on the Ag aggregates could affect the antibacterial ability and biocompatibility of the Ag@Pdop hybrid films. When comprehensively comparing the experimental results, the film prepared for 12 h (Ag@12Pdop) exhibited excellent antibacterial activity against Staphylococcus aureus (S. aureus) and ideal cytocompatibility with human bone mesenchymal stem cells (hBMSCs). In addition, Ag@12Pdop exhibited better anticorrosion performance than polished NiTi in Hank's solution. Meanwhile, Ag@12Pdop showed sustainable Ag release and effectively inhibited the leaching of nickel (Ni) from the NiTi substrate. In this study, a simple method to fabricate Ag-containing films has been presented. The Ag@Pdop hybrid film may be able to significantly prevent infections induced by implantations.