Analytical approaches to support current understanding of exposure, uptake and distributions of engineered nanoparticles by aquatic and terrestrial organisms

Abstract

Initiatives to support the sustainable development of the nanotechnology sector have led to rapid growth in research on the environmental fate, hazards and risk of engineered nanoparticles (ENP). As the field has matured over the last 10 years, a detailed picture of the best methods to track potential forms of exposure, their uptake routes and best methods to identify and track internal fate and distributions following assimilation into organisms has begun to emerge. Here we summarise the current state of the field, focussing particularly on metal and metal oxide ENPs. Studies to date have shown that ENPs undergo a range of physical and chemical transformations in the environment to the extent that exposures to pristine well dispersed materials will occur only rarely in nature. Methods to track assimilation and internal distributions must, therefore, be capable of detecting these modified forms. The uptake mechanisms involved in ENP assimilation may include a range of trans-cellular trafficking and distribution pathways, which can be followed by passage to intracellular compartments. To trace toxicokinetics and distributions, analytical and imaging approaches are available to determine rates, states and forms. When used hierarchically, these tools can map ENP distributions to specific target organs, cell types and organelles, such as endosomes, caveolae and lysosomes and assess speciation states. The first decade of ENP ecotoxicology research, thus, points to an emerging paradigm where exposure is to transformed materials transported into tissues and cells via passive and active pathways within which they can be assimilated and therein identified using a tiered analytical and imaging approach.

Nano-sized Al2O3 reduces acute toxic effects of thiacloprid on the non-biting midge Chironomus riparius

“…[25, 26]) contradicts with the absence of effects in our experiments, but can be attributed to differences in endpoints, test setups, test species and life stages. In this context, it must be noted that the transferability of results between different nanoparticle studies must be handled with extreme care, since nanoparticles – even if they are chemically identical–dramatically change their properties and, likely also their ecotoxicity (or mode of action) when characteristics like size or shape differ [1, 9, 24, 27, 28]. In our case, the absence of toxicity is likely caused by the relatively large size of the nano-Al 2 O 3 particles, since larger particles tend to have less toxic impacts than smaller ones of the same chemical composition [6, 24, 26].…”

“…Nanoparticles can change their properties by ageing and biomodification [2, 9, 18]. Consequently, defecated nano-Al 2 O 3 was sampled to test whether sorption properties of defecated particles differ from pristine ones.…”

“…via wastewater, is very likely, little is known about their fate and effects in the environment [1, 6–8]. Due to these reasons, ENPs have the potential to pose a novel threat to the environment and, consequently, come to focus in ecotoxicology [2, 7, 9]. Many factors, like their abundance in nature, transport within biota and their environment, and their possible persistence, all confounded by their unique properties, e.g.…”

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

“…hyperspectral imaging, confocal microscopy, near infrared fluorescence microscopy) typically cannot resolve individual particles and/or the cellular structures where the particle-associated signal is detected, leaving knowledge gaps on the transportation mechanisms employed and on the actual fate of NPs inside cells (Meyer et al, 2010, Unrine et al, 2010, Hull et al, 2011, Kwok et al, 2012, Ambrosone et al, 2014, Schultz et al, 2015. In contrast, the higher resolution transmission electron microscopy (TEM), which enables a detailed view of NP intracellular localization, is generally confined to a limited number of sections or samples, and may lack insight into the magnitude and the overall consistency of the permeation and translocation phenomenon, when applied to whole organism (Renault et al, 2008, Joubert et al, 2013, Schultz et al, 2015, Wray and Klaine, 2015.…”

Spectral insights into the transformation and distribution of CdSe quantum dots in microorganisms during food-chain transport

“…C. elegans is broadly distributed in soil and water ecosystems and has been widely employed as a toxicology test model 16 . Since the uptake of nanoparticles by bacteria have been intensively reported and well known 17, 18 , here we focus on the downstream step, i.e., how the QDs are transported with the S. onedensis cells into C. elegans , To this end, we used in-vivo synthesized QDs by S. onedensis for simplification, In-situ fluorescence microscopy and Raman mapping were used to monitor the QDs distribution dynamics based on the fluorescence and chemical bond properties of QDs, respectively. The μ -XRF spectroscopy was used to localize the Se element distribution.…”