Fouling-resistant behavior of silver nanoparticle-modified surfaces against the bioadhesion of microalgae

Unwanted adhesion of microalgae on submerged surfaces is a ubiquitous problem across many maritime operations. We explored the strategy of developing a silver nanoparticle (AgNP) coating for antifouling applications in marine and freshwater environments. In situ growth of AgNPs was achieved by a polydopamine (PDA)-based method. A range of most used industrial materials, including glass, polystyrene, stainless steel, paint surface, and even cobblestone, were employed, on which AgNP coatings were built and characterized. We described the fouling-resistant behavior of these AgNP-modified surfaces against two typical fouling organisms: a marine microalga Dunaliella tertiolecta and a freshwater green alga community. The PDA-mediated AgNP deposition strategy was demonstrated applicable for all the above materials; the resulting AgNP coatings showed a significant surface inhibitory effect against the adhesion of microalgae by above 85% in both seawater and freshwater environments. We observed that contact killing was the predominant antifouling mechanism of AgNP-modified surfaces, and the viability of the microalgae cells in bulk media would not be affected. In addition, silver loss from PDA-mediated AgNPs was relatively slow; it could allow the coating to persist for long-term usage. This study showed the potential of preparing environmentally friendly surfaces that can effectively manage biofouling through the direct deposition of AgNP coatings.