Ultrasonic-Assisted Electrodeposition of Cu-TiO₂ Nanocomposite Coatings with Long-Term Antibacterial Activity

Bacterial adhesion, colonization, and spread on aluminum alloy surfaces pose significant risks to human health and public safety. To address these issues, this investigation employed an ultrasonic-assisted electrodeposition method to synthesize long-lasting antibacterial Cu-TiO₂ nanocomposite coatings on porous anodized aluminum oxide (AAO) substrates. Leveraging the cavitation effect of ultrasound, this approach fostered the dispersive incorporation of TiO₂ nanoparticles into the resulting composite coating, thereby expediting the crystallization process of electrodeposition and refining the granular structure. With an optimal concentration of 4 g/L of TiO₂ nanoparticles, the resultant C-4T composite coating displayed a dense and homogeneous microstructure, with TiO₂ nanoparticles predominantly localized at the grain boundaries of Cu grains. Rigorous testing revealed that the surface of the C-4T sample maintained an enduring antibacterial efficacy of 96.8%, even after the outer Cu-TiO₂ layer was worn away. This high level of durability stems from the continuous release of Cu ions and reactive oxygen species (ROS) from the coating's composite region (CR) composed of a porous AAO film and Cu-TiO₂. The porous AAO film, serving as "nanocontainers," offers an ideal deposition carrier for the uniform Cu-TiO₂ composite coating. These agents actively disrupt the integrity and chemical composition of <i>Escherichia coli</i> (<i>E. coli</i>) cells, leading to significant bacterial cell damage and death, thereby conferring superior and persistent antibacterial effects even after specific polishing. This study advances the field of durable antibacterial surface treatments and opens avenues for the sanitary use of nanocomposite coatings in the public health and medical sectors.