Testing of Marine Fouling-Inhibiting Enzymes in a Water-Based Methacrylate Polymer Matrix

Commonly used antifouling coatings rely on the continuous release of biocidal ingredients and are becoming increasingly restricted by legislation. The resulting demand for nonbiocidal technologies involves the search for alternative ingredients and in particular enzymes have received increasing attention. While screening of the antifouling activity of active compounds in solution is well established, the analysis of their activity and in particular anti-biofouling activity when embedded into a coating and even more so in an activated leachate layer is very demanding. Among the challenges is the even distribution throughout the coating and retention of the enzymatic activity. Here a water-based HEMA-methacrylate polymer matrix is presented that aims to mimic the leachate layer and to incorporate active compounds. This technology is used to incorporate several hydrolytically active enzymes-cellulase, protease, and lipase-in a grafting-through approach. After immersion, the enzymes are released in a controlled way during several days. The enzyme-loaded polymer films reduced the attachment of fouling organisms through a combination of their hydrophilic nature and activity of the enzymes. The active contribution of the enzymes became visible in a significant suppression of the accumulation of diatoms and green algal spores compared to the enzyme-free and heat-denatured control coatings.