Antibacterial-renew dual-function anti-biofouling strategy: Self-assembled Schiff-base metal complex coatings built from natural products.

Marine biological fouling has caused huge economic losses and environmental problems. Therefore, it was essential to develop effectively environment-friendly biofouling resistance technology. Here, inspired by the natural module of bacterial secretions, animal and plant extracts, we synthesized Schiff based compounds through Tobramycin (TOB) from Streptomyces and Protocatechualdehyde (PR) from black fern. Furthermore, a dynamic self-renewal Schiff based metal composite coating- (Fe/TOB-PR)n was prepared via layer by layer self-assembly (LBL) method. It was proved to be a versatile coating, which could adhere to different types of substrates. Hydrolytic degradation tests showed that the degradation of the (Fe/TOB-PR)20 coating was regular and controlled. Moreover, compared with the blank glass substrate, the antibacterial rate of (Fe/TOB-PR)20 reached 97 % after 24 h, and the test further shows that the durability of the antibacterial performance benefits from the greater coating thickness. Such coatings displayed excellent anti-bacteria and anti-algae adhesion properties which was attributed to the renewal of the surface and the generation of antibacterial substance (TOB) in the coating. Further, the coating eventually degraded to natural micromolecule monomer, avoiding the occurrence of microplastics. It provides research ideas for fabricating environment-friendly anti-biofouling coatings.