Antibacterial Activity of Vertically Aligned BaTiO3 Nanopillar Arrays via Contact-Mediated Mechanical Membrane Damage and Sono-piezocatalytic Oxidation.

The intrinsic antibacterial activity of cicada and dragonfly wings, via dense arrays of high-aspect-ratio nanopillars and contact-mediated mechanical damage of bacterial membranes, has inspired the design of antibiotic-free antibacterial materials and surfaces. However, the performance of artificially designed nanopillars needs further improvement for any realistic biomedical applications and introducing piezoelectric properties into those nanopillars can greatly enhance the antibacterial efficiency. Here, we report a vertically aligned piezoelectric BaTiO3 nanopillar array that offers strong antibacterial activity due to contact-mediated mechanical membrane damage as well as piezocatalytic oxidative damage. We show that nanopillar-mediated physical damage can offer an up to 60-70% antibacterial rate but a synergistic effect of physical damage and piezocatalysis offers up to 99% antibacterial rates. While nanopillar-mediated physical damage is independent of material composition and maximum activity can be achieved within 15 min of contact, the piezocatalytic oxidative damage increases with increased exposure time of mechanical stress and thus combined effects can be used to achieve nearly 100% antibacterial rates. The designed materials offer a nonantibiotic approach for infection control with application potential in medical devices, implants, and water purification systems.