Biofouling in seawater from a molecular perspective

Biofouling is a long-standing issue with tremendous economic and environmental impact. Current scientific research aims at developing novel strategies to design new antifouling surfaces based on protein repellant polymer surface modifications which tackle the initial stages of biofouling. In this regard zwitterionic polymer brushes have shown to be environmentally benign and are promising as ultralow fouling marine coatings. Here the molecular basis for antifouling surfaces was further enhanced. The ability of surface grafted zwitterionic pSBMA brushes to resist biofouling was assessed by (a) atomic force microscopy (AFM) adhesion experiments, and (b) laboratory fouling studies using cyprid larvae of Balanus amphitrite. For chemical functionalization of AFM tips, fibronectin was chosen as well as RGD peptide motifs covalently attached to PMAA brushes on gold colloidal probes. Our results demonstrate the efficient suppression of protein adsorption on zwitterionic pSBMA brushes, pull-off forces were only hardly detected in AFM measurements. In contrast, on surfaces reported to be strongly protein adhering significant pull-off forces were detected. These results were in agreement with the laboratory fouling studies correlating protein adherence as assessed by pull-off forces with the tendency of barnacle settlement. Hence our proposed AFM based approach enables to locally detect biofouling tendency on surfaces.