Ingestion, fate, and impact of micro-, nano-plastics to living cells

Owing to their small size, MNPs can crossbiological barriers, accumulate in organs, and interact with cellularstructures. This thesis investigates the toxicological effects of MNPs,focusing on the influence of polymer type, particle size, and exposureconcentration, using human intestinal (Caco-2), hepatic (HepG2), and neuronal(SH-SY5Y) cell models.</p><p>Experimental studies withpolystyrene (PS) particles (30 nm, 100 nm, and 1.1 μm) demonstrated clear size-and cell-type-dependent toxicity.

High Content Analysis revealed that smallerPS nanoparticles induced mitochondrial dysfunction, oxidative stress, andapoptotic responses, particularly in HepG2 and SH-SY5Y cells, while Caco-2cells showed limited sensitivity. O-PTIR spectroscopy identified localisedlipid accumulation and structural reorganisation following PS exposure,indicating disruption of cellular homeostasis. Transcriptomic analyses furthershowed alterations in genes involved in mitochondrial function, apoptosis,autophagy, and inflammation, with low-dose exposure eliciting adaptiveresponses and higher doses triggering pro-inflammatory and pro-apoptoticpathways.</p><p>The toxicity of biodegradablepolymers was also assessed using nano-sized polylactic acid (PLA) andpolycaprolactone (PCL).