Dottorato in MORFOGENESI E INGEGNERIA TISSUTALE

Titolo della tesi: Detection of Micro- and Nano- Plastics in Water and Assessment of their Potential Health Effects

Biological Issue: The pervasive contamination of micro- and nano-plastics (MNPs) is of great concern due to their potential impacts on human health and ecosystems. MNPs originate from various sources, from purpose manufacture to the degradation of larger plastic debris and have been detected in human tissues. Their presence in human bodies has raised concerns about toxicity and inflammation. Nanoplastics (NPs) are particularly concerned due to their smaller size and the formation of protein corona in biological fluids, which can alter their effects on biological systems. Despite growing awareness, there are no standardized methods for sampling and analyzing MNPs, and their health impacts remain unclear. This project aims to develop a fast, portable method for detecting and quantifying MNPs in aquatic environments and to investigate their harmful effects on human cells, particularly the role of surface charge and protein corona formation. Results: The Fluorescence Lifetime Analysis (FLA) system developed in this study successfully detected MNPs, including polystyrene (PS), polyethylene terephthalate (PET) and polyvinyl chloride (PVC) at concentrations as low as 0.01 mg/mL. Although differentiating between these plastics was challenging due to similar fluorescence lifetimes, these results enriched the phasor fingerprint database of MNPs and mapped the graphical relationship between MNP concentration and their phasor fingerprints. In vitro studies suggested MNPs with irregular shapes and positive surface charge caused more damage to cells than spherical, negatively charged particles. These particles exerted mechanical stress, disrupted cellular signaling, and deregulated autophagy. The formation of protein corona altered MNP interactions with cells and reduced their toxic effects. However, the influence of protein corona depended on its specific composition, which was in turn determined by MNPs' physicochemical properties. Additionally, the studies revealed that MNPs could modulate immune responses. Conclusions: This project employed a dual approach to address concerns about MNP pollution. On one hand, it advanced the development of a portable, cost-effective tool for detecting MNPs in water, with potential for environmental monitoring. On the other hand, in vitro studies underscored the potential dangers of MNP exposure to human health. Moreover, the results emphasized the importance of considering the protein corona when assessing the potential health risks of MNPs.