Antifouling properties of zinc oxide nanorod coatings

<div><p>In laboratory experiments, the antifouling (AF) properties of zinc oxide (ZnO) nanorod coatings were investigated using the marine bacterium <i>Acinetobacter</i> sp. AZ4C, larvae of the bryozoan <i>Bugula neritina</i> and the microalga <i>Tetraselmis</i> sp. ZnO nanorod coatings were fabricated on microscope glass substrata by a simple hydrothermal technique using two different molar concentrations (5 and 10 mM) of zinc precursors. These coatings were tested for 5 h under artificial sunlight (1060 W m⁻² or 530 W m⁻²) and in the dark (no irradiation). In the presence of light, both the ZnO nanorod coatings significantly reduced the density of <i>Acinetobacter</i> sp. AZ4C and <i>Tetraselmis</i> sp. in comparison to the control (microscope glass substratum without a ZnO coating). High mortality and low settlement of <i>B. neritina</i> larvae was observed on ZnO nanorod coatings subjected to light irradiation. In darkness, neither mortality nor enhanced settlement of larvae was observed. Larvae of <i>B. neritina</i> were not affected by Zn²⁺ ions. The AF effect of the ZnO nanorod coatings was thus attributed to the reactive oxygen species (ROS) produced by photocatalysis. It was concluded that ZnO nanorod coatings effectively prevented marine micro and macrofouling in static conditions.</p>