Coordination-driven antifouling spray coating using a sulfated polysaccharide Fucoidan

Surface contamination and infection caused by bacteria are recognized as acute problems in daily life and human health. To address these issues, surface coatings with antifouling materials to hinder bacterial adhesion and growth on surfaces have been widely used. Although synthetic polymers have their own merits, natural polysaccharides have recently attracted considerable interest for use as antifouling coatings owing to their sustainability and natural abundance. Metal coordination has recently been utilized to achieve stable antifouling polysaccharide coatings. However, there is an unmet need to fabricate antifouling polysaccharide coatings in a direct way without surface primer layer. Herein, fucoidan, a brown algae-derived polysaccharide, was employed as an antifouling surface coating. For efficient coating, fucoidan was conjugated with catechol groups to produce fucoidan catechol (FD-C). Co-spraying FD-C and ferric (FeIII) ions onto surfaces enabled the application of coordination-driven antifouling coatings without any surface primer layer in a thickness-controllable manner. Compared with the control, the FD-C/FeIII coatings achieved 99.2% and 95.6% reduction in E. coli and S. aureus adhesion, respectively, demonstrating the antifouling effects of the coatings. Remarkably, spray-based antifouling coatings have long-term durability, retaining excellent antifouling performance for up to six weeks. Coordination-driven spray coatings can be applied to various substrates including titanium dioxide (a material with medical applications), stainless steel, and seat handles (used in public transportation systems). Given its facile and versatile coating capability, we believe that direct FD-C/FeIII co-spraying can serve as an effective approach to suppress bacterial contamination and resultant infections.