(420ar) Linking the Electronic Character of Single-Wall Carbon Nanotubes to Their Biological Impacts Using a Model Aquatic Organism

Over the last decade, extensive research has been completed on the potential threat single-walled carbon nanotubes (SWCNTs) cause to living organisms upon release to aquatic systems.  Most studies have focused on the effect of SWCNT length, diameter, and metallic impurities in traditional dose response assays.  However, very little work has been done attempting to elucidate the biological response of test organisms based on the electronic structure or SWCNTs, i.e., metallic (m-) or semiconducting (s-) species, if any.  A commonly used method to produce well separated fractions of these two SWCNT types is column-based, through interaction with agarose gels.  Our previous work describing the driving forces at play during separation, and the source of selectivity of the process has allowed us to create high purity fractions of both m-, and s-SWCNTs appropriate for use in eco-toxicity. Within, we describe our methods for the separation, purification, and stabilization type separated SWCNTs to be used in traditional dose response studies.  Additionally, we report significant differences to the biological response of the test organism P. subcapitata when exposed to these isolated fractions of m- and s-SWCNTs.  Importantly, our results suggest that the observed toxicity of each species is influenced by a variety of factors including electronic type, surfactant concentration, and synthesis method.  Finally, we propose that hydrogel separation of SWCNTs has potential for use as a simple bench scale tool to predict SWCNT toxicity in natural systems.