Anti-bacterial superhydrophobic silver on diverse substrates based on the mussel-inspired polydopamine

Based on the mussel-inspired polydopamine, superhydrophobic silver on diverse substrates of titanium alloy, silicon and polypropylene was successfully fabricated via a facile silver mirror reaction. The surface morphology, surface chemistry, and surface wettability were evaluated by field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle meter, respectively. The stability of the superhydrophobic state was evaluated by monitoring the contact angle variation for the superhydrophobic sample exposing to air for 60 days or contacting with a water droplet in a saturated vapor atmosphere for 70 h. Anti-bacterial effect was evaluated using a series of assays, such as the anti-bacterial activity assay according to the Japanese Industrial Standard JIS Z 2801: 2010, the bacterial inhibition ring assay, and the visualization of bacteria on samples by scanning electron microscopy. Experimental results showed that the superhydrophobic state could be retained in the stability test, and the superhydrophobic silver exhibited strong anti-bacterial ability against Escherichia coli and Staphylococcus aureus due to the releasing of Ag+ bactericide and the superhydrophobicity.