Using highly characterized gold nanoparticles this study determined that ligand identity, nanoparticle surface charge and aggregation type alters toxicity of gold nanoparticles to Daphnia magna.

Lithium intercalation compounds such as lithium nickel manganese cobalt oxide (NMC) and lithium cobalt oxide (LCO) are used extensively in lithium batteries. Because there is currently little economic incentive for recycling, chances are greater that batteries will end up in landfills or waste in the environment. In addition, the toxicity of these battery materials traditionally has not been part of the design process. Therefore, to determine the environmental impact and the possibility of alternative battery materials, representative complex battery nanomaterials, LCO and NMC, were synthesized, and toxicity was assessed in Daphnia magna. Toxicity was determined by assessing LCO and NMC at concentrations in the range of 0.1 to 25 mg/L. Acute studies (48 h) showed no effect to daphnid survival at 25 mg/L, whereas chronic studies (21 d) show significant impacts to daphnid reproduction and survival at concentrations of 0.25 mg/L for LCO and 1.0 mg/L for NMC. Dissolved metal exposures showed no effect at the amounts measured in suspension, and supernatant controls could not reproduce the effects of the particles, indicating a nanomaterial-specific impact. Genes explored in the present study were actin, glutathione-s-transferase, catalase, 18s, metallothionein, heat shock protein, and vitellogenin. Down-regulation of genes important in metal detoxification, metabolism, and cell maintenance was observed in a dose-dependent manner. The results show that battery material chemical composition can be altered to minimize environmental impacts. Environ Toxicol Chem 2017;36:2493-2502. © 2017 SETAC.

Mechanisms of corona formation around nanomaterials remain enigmatic. Here, we provide evidence for spontaneous lipid corona formation that engenders new particle properties without the need for active mixing upon attachment to stationary and suspended lipid bilayer membranes. The mechanism of lipid corona formation can be used to improve control over nano-bio interactions and to help understand why some nanomaterial-ligand combinations are detrimental to organisms but others are not. SUMMARYAlthough mixing nanoparticles with certain biological molecules can result in coronas that afford some control over how engineered nanomaterials interact with living systems, corona formation mechanisms remain enigmatic. Here, we report results from experiments and computer simulations that provide concrete lines of evidence for spontaneous lipid corona formation without active mixing upon attachment to stationary and suspended lipid bilayer membranes. Experiments show that polycation-wrapped particles disrupt the tails of zwitterionic lipids, increase bilayer fluidity, and leave the membrane with reduced z potentials. Computer simulations suggest that the contact ion pairing between the lipid head groups and the polycations' ammonium groups leads to the formation of stable, albeit fragmented, lipid bilayer coronas. The mechanistic insight regarding lipid corona formation can be used to improve control over nanobio interactions and to help understand why some nanomaterial-ligand combinations are detrimental to organisms but others are not.

Gene expression patterns indicate different impacts of charged nanoparticles across two model species.

The toxicity of nanomaterials depends on the basic interaction of the chemistry of the material with the molecular pathways in an organism. To design safe and sustainable nanomaterials, more detailed information on the molecular interaction and biochemical machinery that is altered in an organism upon contact with a nanomaterial is needed. There are a multitude of papers now on the toxicity of nanomaterials to various model organisms from human to ecological models, but many focus on acute high dose exposures and research on the toxicity of other chemicals has shown that the dose of a chemical can have a tremendous impact on the pathways that are affected within the organism. The most common pathways investigated in nanotoxicity experiments are related to oxidative stress, yet oxidative stress can be a temporary and natural response to an insult without a negative outcome. There are a multitude of other potential mechanisms that may be triggered in response to a toxin at sublethal exposures. Here we present a review documenting the evidence to date on the indicators of the molecular response to nanomaterials from in vitro and in vivo studies. Alternative pathways as indicated by single biomarker, global gene expression studies and next generation sequencing approaches are discussed as well as the impacts of nanomaterial type, dose, and the types of system studied. Specific mechanisms that are impacted by a nanomaterial can be used as the basis of better high-throughput methods for evaluating how nanomaterial chemistry impacts toxicity and support models to predict the toxicity of future nanomaterials.

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<a></a><a>While mixing nanoparticles with certain biological molecules can result in coronas that afford some control over how engineered nanomaterials interact with living systems, corona formation mechanisms remain enigmatic. Here, we report spontaneous lipid corona formation, i.e. without active mixing, upon attachment to stationary lipid bilayer model membranes and bacterial cell envelopes, and present ribosome-specific outcomes for multi-cellular organisms. Experiments show that polycation-wrapped particles disrupt the tails of zwitterionic lipids, increase bilayer fluidity, and leave the membrane with reduced ζ-potentials. Computer simulations show contact ion pairing between the lipid headgroups and the polycations’ ammonium groups leads to the formation of stable, albeit fragmented, lipid bilayer coronas, while microscopy shows fragmented bilayers around nanoparticles after interacting with <i>Shewanella oneidensis</i>. Our mechanistic insight can be used to improve control over nano-bio interactions and to help understand why some nanomaterial/ligand combinations are detrimental to organisms, like <i>Daphnia magna</i>, while others are not. </a>

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