Difference and association of antibacterial and bacterial anti-adhesive performances between smart Ag/AgCl/TiO2 composite surfaces with switchable wettability

Bacterial adhesion on the Ti-based materials, which can lead to microbial corrosion, pipe blockage, transplant infection and other problems, has attracted considerable attention. Developing superhydrophobic TiO2/Ti composite surface with release-killing and photocatalytic bactericidal performances has been confirmed to be an effective strategy for preventing bacterial adhesion. However, there are certain limitations, such as efficient bactericidal performance only for UV photocatalytic but low efficiency for solar light, and superhydrophobic surface not conducive to release-killing. Herein, a smart bacterial anti-adhesive Ti-based surface with switchable hydrophobicity–hydrophilicity is used to prevent the adhesion of two model bacteria: Escherichia coli and Staphylococcus aureus. The presence of TiO2 nanotube arrays on Ti endows it with hydrophobicity–hydrophilicity switch under ultraviolet radiation. Moreover, decoration with Ag/AgCl nanoparticles (NPs) promotes the solar light photocatalytic release of reactive oxygen species (ROS), greatly improving the bactericidal performance. The experimental results and the molecular dynamics (MD) simulation confirmed that the superhydrophilic surface is more conducive to release-killing compared to the superhydrophobic one. The hydration layer formed endows it with excellent bacterial anti-adhesion. The superhydrophobic surface in a Cassie–Baxter state exhibits additional prominent bacterial anti-adhesion than a superhydrophilic one because of the air layer and low adhesive force. This new material confirmed to be chemical and abrasion resistant, maintaining its excellent performances after cyclic testing. The strategy of designing a solar light photocatalytic bactericidal and constructing bacterial anti-adhesive smart surfaces with switchable wettability opens up a new avenue for research on bacterial anti-adhesion.