Bioinspired zwitterionic dopamine-functionalized liquid-metal nanodroplets for antifouling application

With their low toxicity and unique antibacterial properties, gallium-based liquid metals (GLM) exhibit promising applications as marine antifouling agents. Herein, the zwitterionic molecule-functionalized GLM nanodroplets were successfully prepared via probe-type sonication and self-assembled on-site with zwitterionic dopamine sulfonate (ZDS) ligand. The as-prepared ZDS-modified GLM (ZDS@GLM) nanodroplets manifested fine antibacterial properties attributable to the synergistic effect existing between gallium ions and the quaternary ammonium group in ZDS. Meanwhile, the surface hydration layer formed by ZDS ligand equips the ZDS@GLM nanodroplets with exceptional antifouling and lubrication properties. The as-prepared ZDS@GLM nanodroplets can be effectively blended with the self-polishing coating as a filler to synthesize the functionalized nanocomposite coating. Due to the remarkable antibacterial properties possessed by ZDS@GLM nanodroplets and surface hydration layer generated by zwitterionic dopamine ligand, the ZDS@GLM-based self-polishing coatings demonstrate potent antifouling properties (above 50% E. coli and S. aureus; 65% Porphyridium were removed). Furthermore, the ZDS@GLM nanodroplets can endow the PDMS (Polydimethylsiloxane) coating with self-healing properties by means of crosslinking the uncured vinyl under the exposed GLM initiating polymerization.