Implications of aspect ratio on the uptake and nanotoxicity of gold nanomaterials

Abstract

Colloidally stable gold nanoparticles are commonly used for biomedical and industrial applications due to their unique physicochemical properties. However, the post-application fate of these nanoparticles in the environment requires consideration. In this study, we evaluated how nanoparticle size and shape impact the uptake and toxicity of gold nanoparticles to the filter-feeding bivalve, Corbicula fluminea. Our results indicate that the organismal uptake rate increases with an increase in nanoparticle size and anisotropy. Rate constants for 19 nm and 45 nm BSA-coated gold nanoparticles and aspect ratio (length/width) 4 and aspect ratio 8 BSA coated gold nanorods were 0.020 ± 0.002, 0.045 ± 0.008, 0.025 ± 0.003, and 0.064 ± 0.012 h−1 respectively. Both spherical and elongated gold nanoparticles were readily detected in the digestive glands, gills, (pseudo)feces, and on the shell exterior following exposure. The presence of nanoparticles in non-digestive tissues suggests that the nanoparticles were internalized and consumed by C. fluminea. The toxicity results indicate that for the tested concentration and exposure period that the tested gold nanoparticles were not acutely toxic (i.e., not lethal). However, the nanoparticles significantly inhibited the activity of some antioxidant enzymes within gill and digestive gland tissues, potentially impairing the clams antioxidant system.