Silver NanoparticleAlgae Interactions: Oxidative Dissolution, Reactive Oxygen Species Generation and Synergistic Toxic Effects

The short-term toxicity of citrate-stabilized silver nanoparticles (AgNPs) and ionic silver Ag­(I) to the ichthyotoxic marine raphidophyte <i>Chattonella marina</i> has been examined using the fluorometric indicator alamarBlue. Aggregation and dissolution of AgNPs occurred after addition to GSe medium while uptake of dissolved Ag­(I) occurred in the presence of <i>C. marina</i>. Based on total silver mass, toxicity was much higher for Ag­(I) than for AgNPs. Cysteine, a strong Ag­(I) ligand, completely removed the inhibitory effects of Ag­(I) and AgNPs on the metabolic activity of <i>C. marina</i>, suggesting that the toxicity of AgNPs was due to the release of Ag­(I). Synergistic toxic effects of AgNPs/Ag­(I) and <i>C. marina</i> to fish gill cells were observed with these effects possibly attributable to enhancement in the generation of reactive oxygen species by <i>C. marina</i> on exposure of the organism to silver