engleski

Synthesis and effects of polystyrene nanoplastic exposure on the haemolymph of Mediterranean mussel Mytilus galloprovincialis

Microplastics, deriving from the breakdown of macro-scale polymer-based products, have become the focus of much research over the past number of years due to their ubiquity in the environment and their potentially negative impact on biota. Moreover, the possibility of bioaccumulation and biomagnification in the food chain may ultimately impact upon human health. However, continued environmental weathering of microplastics likely gives rise to increasingly smaller particles, eventually reaching the nano-scale size range. Nanoplastics are particularly interesting as their small size (1 ‒ 1000 nm) overlaps with the size of the particles ingested by filter feeders. However, determining the distribution and fate of such polymer nanoparticles in biota is particularly challenging using instrumental methods of analysis. The aim of the work reported herein was to synthesise labelled polystyrene nanoparticles of tailored diameter and to investigate their uptake, bio-distribution and impact on Mediterranean mussel Mytilus galloprovincialis. Non-surface-functionalised virgin polystyrene nanoparticles with encapsulated ethidium bromide were characterised by scanning electron microscopy and transmission electron microscopy. Subsequently, M. galloprovincialis was treated with the nanoparticles at concentrations in the range of 100 ‒ 1000 mg L-1 with an exposure time of 24 h. The accumulation of nanoplastics on the gills was tracked by epi-fluorescence microscopy with significant quantities agglomerated among the gill filaments. As an indicator of toxicity, the impact of the nanoplastics on the immune system of the mussels was investigated by determining cell viability and changes to the number of circulating haemocytes. Even though the exposure time was short, higher concentrations of nanoplastics were found to reduce both the number and cell viability of mussel haemocytes. Furthermore, the stability of lysosomal membranes in haemocytes was also found to have significantly decreased at higher nanoparticle concentrations. Overall, this work has used a range of microscopy and spectroscopy techniques to demonstrate how M. galloprovincialis rapidly takes up nanoplastics from the water column where they accumulate on gills and pass into the digestive system. The presence of these nanoplastics were found to deleteriously impact on the mussel's immune system, even after a short experimental exposure. Ultimately, this work is a step in the direction of creating tailored polymer nanoparticles that will allow tracking of nanoplastics' pathways through tissues and cells.

nanoplastic ; polystyrene ; mussel ; immune system

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