Anti-biofouling potential of extremely water-repellent carbon soot coatings immersed in a highly-contaminated seawater swamp

The undesired translocation of marine microorganisms during sailing and the excessive expenditures for ship hull repairment due to biofouling could be circumvented using superhydrophobic coatings. Unfortunately, the combined effect of underwater currents and colonizing activity of multitudinous foulants on the anti-microbial performance of existing non-wettable materials is still at infant stage. The paramount objective here is to evaluate for the first time the potential of two mechanically durable water-repellent soot coatings towards the inhibition of bacterial proliferation in "real-life" outdoor conditions. We demonstrate that upon one-week immersion in a seawater swamp, both specimens lose non-wettability due to dissolution of the trapped gas layer into the water basin, but yet manage to retard the biofilm development, compared to uncoated iron surfaces, and halt the settlement of some Gram-negative and Gram-positive bacterial strains. The noticed selectiveness in the anti-fouling behavior of tested samples is presumably attributed to differences in the cell envelopes, the extent of elicit oxidative stress and soot-mediated formation of toxic ammonia molecules via hydrogen bonding. These unknown so far anti-bacterial mechanisms of the soot expand the horizons of practical applicability beyond the conventional framework and emphasize on its possible future use as a therapeutic agent.