Waterborne Antifouling Paints Containing Nanometric Copper and Silver against Marine Bacillus Species

Due to the concern to find an alternative to reduce the colonization (microfouling and macrofouling) or the biocorrosion of surfaces submerged for long periods in water, we evaluated the antifouling activity of a commercial paint added with silver nanoparticles (AgNP's) and copper nanoparticles (CuNP's), beside copper-soybean chelate, by electrolytic synthesis, using them in low concentrations (6.94E - 04 mg Ag g^-1 paint, 9.07E - 03 mg Cu g^-1 paint, and 1.14E - 02 mg Cu g^-1 paint, respectively). The test for paint samples was carried out by JIS Z2801-ISO 22196 for periods of initial time, 6 months, and 12 months, against three bacterial strains of marine origin, Bacillus subtilis, Bacillus pumilus, and Bacillus altitudinis. It was possible to demonstrate, according to the standard, that the sample with the greatest antimicrobial activity was the copper-soybean chelate against two of the three strains studied (B. pumilus with R = 2.11 and B. subtilis with R = 2.41), which represents more than 99% of bacterial inhibition. Therefore, we considered a novel option for inhibiting bacterial growth with nanoparticles as antifouling additives.