Correlative microscopic analysis of uptake, localisation and transformations of nanoscale particles in freshwater foodwebs

The potential for human exposure to manufactured nanoparticles (NPs) has increased in recent years, in part through their incorporation into a wide range of commercial goods and medical applications. Their widespread use is raising concerns regarding their efficacy and safety, and impacts on freshwater ecosystems and the services they provide. Techniques for investigation of NP uptake into freshwater indicator species such as biofilms and Daphnia magna (water flea) are critically important. We have developed correlative methods for use with cells (Guggenheim et al, 2016, Guggenheim et al, 2017), combining the advantages of (1) Transmission Electron Microscopy (TEM), which provides ultrahigh resolution, but involves cumbersome sample preparation rendering the technique incompatible with live cell imaging, (2) Confocal reflectance microscopy which provides optical sectioning and live imaging capabilities, with little sample preparation, but is diffraction limited, thus the X-Y resolution is restricted to ~250 nm, substantially larger than the <100 nm size of NPs; and (3) Super-resolution light microscopy which overcomes the diffraction limit, providing increased X-Y resolution, including automated image alignment and reconstruction. Figure 1 shows an example of the resulting images of NP localisation.
The present CENTA2 PhD project will extend correlative microscopy approaches to unicellular freshwater organisms (algae and diatoms), and their communities (biofilms) and to guts extracted from exposed Daphnia magna (water flea) as important indicator species for toxicity, and keystone species for foodweb analysis. NP uptake and localisation in the freshwater species will be correlated with the nature and evolution of the biomolecule corona acquired by the NPs. The impact of secreted biomolecule on uptake and toxicity of NPs has been demonstrated (Nasser et al, 2016; Briffa et al, 2018), but has not yet been evaluated in the context of NP uptake and localisation, nor in conjunction with super-resolution imaging approaches for biomolecule exchange such as STORM – Stochastic optical reconstruction microscopy (STORM). The approach utilised will utilise simple (2 species) biofilms and extracted daphnia gut which would be exposed under flow conditions. Guts will be extracted pre- and post-exposure to nanoparticles in order to evaluate their function ex vivo.
The project leverages a strong existing collaboration between UoB and CEH, and will align with and benefit from collaboration with the Horizon2020 project RISKGONE.
Sciex will act as a CASE partner specially on the aspects of the acquired corona and its evolution during uptake and transport in cells, and exchange of biomolecules following final localisation.
Please contact Professor Iseult Lynch ([Email Address Removed]) for further details.