Influence of cysteine and bovine serum albumin on silver nanoparticle stability, dissolution, and toxicity to Phanerochaete chrysosporium

The transport and environmental persistence of silver nanoparticles (AgNPs) after exposure to dissolved organic matter (DOM) are influenced by their stability and dissolution. In addition, their toxicity to microorganisms is influenced by the release of silver ions (Ag+). Here, we characterize the stability and dissolution of citrate-stabilized AgNPs, and their toxicity to a white-rot fungus, Phanerochaete chrysosporium (P. chrysosporium), following exposure to either cysteine (CYS) or bovine serum albumin (BSA). The results indicated that both CYS and BSA changed the diameter, zeta potential, and Ag+ dissolution of AgNPs. Bacterial viability and intracellular reactive oxygen species (ROS) levels were investigated to determine the toxicity of AgNPs to P. chrysosporium. In this study, CYS decreased the inhibitory effects of 100 μg L−1 Ag+ and 10 mg L−1 AgNPs in a concentration-dependent manner. At higher concentrations of CYS, the toxicity of Ag+ and AgNPs was reduced dramatically. However, cell viability decreased at higher BSA concentrations (≥50 mg L−1), suggesting a more complex reaction than simply binding to the released Ag+. Addition of 10 mg L−1 AgNPs significantly stimulated ROS production, but the addition of CYS and BSA decreased the ROS level in a concentration-dependent manner. In summary, our results provide useful information in understanding the fate, transformation, and toxicity of citrate-stabilized AgNPs in the natural environment.