Due to the unique physicochemical properties of engineered nanomaterials, they are being used in increasing amounts in consumer products. This increased use of nano-enabled products leads to an increased probability that nanomaterials will be released into the environment at any stage of the product’s lifetime, where the interaction of engineered nanomaterials with organisms is not well understood. This work uses a panel of five Gram-negative bacterial models that occupy diverse habitats and have different environmental roles to assess the impact of polyallylamine hydrochloride-wrapped gold nanoparticles (PAH AuNPs). Due to the diversity of these bacteria, they are more representative of bacteria in the different environments NPs may end up in. Minimum bactericidal concentration data for PAH AuNPs shows that the different bacteria experience a range of toxicities after NP exposure. This is a benefit of the panel, which serves as a platform for screening the toxicity of different nanoparticles. This panel shows which bacteria are experiencing the most toxicity, identifying those that are good candidates for follow-on work to investigate the mechanism of nanoparticle toxicity. PAH AuNP binding to the bacterial surface was visualized with transmission electron microscopy and quantified with flow cytometry. To further probe the interaction of PAH with the bacterial surface, a process mediated by the lipopolysaccharides (LPS) on Gram-negative bacteria, all-atom models using LPS with different characteristics were employed. These models show that overall charge and the number of phosphate groups in LPS impact PAH binding. Simulations were also performed to explore the energy differences in binding of PAH to a model smooth and rough LPS structure. These simulations represent a method with which to further understand the toxicity of colloidal nanoparticles in the environment. This panel can be adapted for a range of nanomaterials beyond AuNPs, which is beneficial since using a varied assortment of environmentally-relevant Gram-negative bacteria introduces biological complexity to obtain more generalizable toxicity results when assessing nanotoxicity.

Using an environmentally-relevant panel of Gram-negative bacteria to assess the toxicity of polyelectrolyte-wrapped gold nanoparticles

255th National Meeting (2018)

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