Dissolution and bandgap paradigms for predicting the toxicity of metal oxide nanoparticles in the marine environment: an in vivo study with oyster embryos

Abstract

Dissolution and bandgap paradigms have been proposed for predicting the ability of metal oxide nanoparticles (NPs) to induce oxidative stress in different in vitro and in vivo models. Here, we addressed the effectiveness of these paradigms in vivo and under conditions typical of the marine environment, a final sink for many NPs released through aquatic systems. We used ZnO and MnO NPs as models for dissolution and bandgap paradigms, respectively, and CeO NPs to assess reactive oxygen radical (ROS) production via Fenton-like reactions in vivo. Oyster embryos were exposed to 0.5-500 μM of each test NP over 24 h and oxidative stress was determined as a primary toxicity pathway across successive levels of biological complexity, with arrested development as the main pathological outcome. NPs were actively ingested by oyster larvae and entered cells. Dissolution was a viable paradigm for predicting the toxicity of NPs in the marine environment, whereas the surface reactivity based paradigms (i.e. bandgap and ROS generation via Fenton-like reaction) were not supported under seawater conditions. Bio-imaging identified potential cellular storage-disposal sites of solid particles that could ameliorate the toxicological behavior of non-dissolving NPs, whilst abiotic screening of surface reactivity suggested that the adsorption-complexation of surface active sites by seawater ions could provide a valuable hypothesis to explain the quenching of the intrinsic oxidation potential of MnO NPs in seawater.

Gold nanoparticles ingested by oyster larvae are internalized by cells through an alimentary endocytic pathway

“…We previously observed endocytotic forms similar to those illustrated here in oyster larvae exposed to manganese dioxide (MnO2) NPs, but were unable to trace them throughout the larval body at this level of resolution due to their lower electron density and irregular shape (Noventa et al, 2018a, Noventa et al, 2018b. By considering the substantial diversity of these two nanomaterials (i.e.…”

“…Early larval stages of bivalves have not been widely used until now to study the uptake and impact of nanoparticles (Ringwood et al, 2009, Kadar et al, 2010, Ringwood et al, 2010, Noventa et al, 2018a, Noventa et al, 2018b, despite their ability to bioconcentrate solid particles and the bioimaging advantage offered by their transparency and small size (approximately 70 µm). Early veliger larvae (alias D-shell shaped larvae, prodissoconch I) actively feed on suspended food particles, processing them through a well developed digestive apparatus (Yonge, 1926b, Millar, 1955, Galtsoff, 1964, Elston, 1980a, Waller, 1981, Bayne, 2017 (Figure 1).…”

A Review of the Synthesis and Applications of Polymer–Nanoclay Composites

“…Several polymer-nanoclay composites are able to remove various pollutants from aqueous solutions and have been shown to be effective in water treatment processes. Safety concerns remain regarding the potential for nanoparticles to be released into the environment and cause harm via chemical transformation, biological transformation, physical transformation or aggregation, and interactions between particles and natural organic matter or biomolecules [219][220][221]. Consequently, the further development of such materials should consider synthesis strategies, modes of application, regeneration potential, as well as environmental and human health implications.…”

Nanomaterial Transformations in the Environment: Effects of Changing Exposure Forms on Bioaccumulation and Toxicity

“…Dissolution is established for many reactive nanomaterials and has been widely linked to the development of toxicity through the release of toxic ions. [ 38,39 ] It has been demonstrated that NMs frequently show lower toxicity than their metal ion equivalents. In a metaanalysis of studies comparing the toxicity of NMs and the corresponding “ionic” form, Notter et al [ 40 ] found that 11 of 269 (4.1%) of Ag; 12 of 72 (20.8%) of ZnO, and 0 of 68 (0%) of CuO aquatic toxicity studies showed higher toxicity for the NM that the ion.…”