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Comparative evaluation of molecular mechanisms triggered by differently functionalized polystyrene nanoplastics in human colon cell lines
Summary
Researchers compared molecular and cellular mechanisms triggered by differently surface-functionalized micro- and nanoplastics in human intestinal and liver cells, finding that surface chemistry strongly determines biological effects. Functionalized particles elicited distinct patterns of oxidative stress, inflammation, and membrane damage compared to unfunctionalized particles.
The plastic waste can be progressive disintegrated into microscale (MPs; 1 µm-5 mm) and nanoscale particles (NPs; 1 nm-1 µm) through the long-term influence of mechanical forces of water, ultraviolet radiation, and biological degradation. Humans are mainly exposed to MPs and NPs through oral intake. Following their ingestion, particles can penetrate intestinal mucus, be transported to reach the circulatory system, and deposit in various organs, posing a serious risk to health. Polystyrene (PS) is an important thermoplastic found in disposable drinking cups, packaging, and personal care products. In the present study, unmodified PS or differently functionalized NPs (PS-COOH and PS-NH2; 100 nm in size) were selected as experimental models and administered to colorectal adenocarcinoma (Caco-2 and HT-29) and normal colon (CCD-841) cell lines, representing the cells potentially most exposed to microplastics. A comparison of internalization process into cells among differently functionalized NPs was performed by confocal microscopy and cytofluorimetric analysis. Fluorescent PS-COOH and PS-NH2 NPs were detected inside the cells after 2 hour-incubation, and they continued to accumulate within 24 hours. The impact of PS, PS-COOH and PS-NH2 (from 1 to 100 µg/mL) on Caco-2 and CCD-841 cell viability was evaluated after 48 hour- and 96 hour-incubation period by MTT assay: PS-NH2 significantly reduced cell viability in a dose and time-dependent way, while treatments with PS and PS-COOH were well tolerated and only the highest concentrations of PS-COOH were able to decrease cell viability after 96 hours. Western blot analysis revealed an inhibition of MAPK/ERK pathway, one of the main signaling cascades sustaining cell proliferation, by NPs treatment. Similar results were obtained on breast cancer cells, where the effect of protein corona on NPs toxicity was also evaluated. A transcriptome analysis will shed light on molecular mechanisms involved in the cell response to NPs. Funded by "Next Generation EU". Also see: https://micro2024.sciencesconf.org/559557/document