A hybrid coating composed of hydroxyapatite (HA), Ag nanoparticles (NPs), and chitosan (CS) was successfully prepared on a Ti substrate by a layer-by-layer assembly process. A polydopamine-assisted (PDA-assisted) coating showed a good bond with HA. Ag NPs were uniformly distributed into the hybrid coating through a solution method and ultraviolet light reduction. A CS nanofilm was deposited via spin-coating to control the release of Ag from the hybrid coating. The results disclosed that the 3-layer CS coating could efficiently control the release of Ag from the hybrid coating via the Fickian diffusion mechanism and that the PDA/HA/Ag/CS-1 coating exhibited antibacterial ratios of 63.0% and 51.8% against E. coli and S. aureus, respectively. Furthermore, the normal structure of E. coli was obviously destroyed by two types of Ag doped coatings. The cell viability assay showed that CS effectively reduced the cytotoxicity of the hybrid coating after a 7 day incubation. The hybrid coating presented high ALP activities at days 3 and 14. The results reveal that hybrid coatings can endow Ti implants with good antibacterial capability as well as cell viability and osteogenic activity.

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A nanostructured film composed of one-dimensional titanate nanowires (TNWs) was employed as a carrier of Ag nanoparticles and chitosan (CS) to improve the surface antibacterial activity and biocompatibility of titanium implants. A TNWs film was produced on a Ti substrate by an alkali hydrothermal reaction and subsequently doped by Ag nanoparticles through an ultraviolet light chemical reduction. The CS nanofilm was deposited on the Ag nanoparticles through a spin-assisted layer by layer assembly method. The results disclosed that Ag nanoparticles were successfully carried by TNWs and homogeneously distributed on the entire surface. Moreover, a CS nanofilm was also successfully deposited on the Ag nanoparticles. Antibacterial tests showed that the samples modified with a higher initial concentration of AgNO3 solution exhibited better antibacterial activity, and that a CS nanofilm could further improve the antibacterial activity of the TNWs. Cell viability and ALP tests revealed that the release of Ag(+) was detrimental for the growth, proliferation, and differentiation of MC3T3, and that CS could lower the negative effects of Ag gradually as the incubation time increased.

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