Studies
concerning the toxicity of pollutant-loaded nanoplastics
(NPs) toward humans are still in their infancy. Here, we evaluated
the adsorption of microcystins (MCs) by pristine and aged polystyrene
nanoplastics (PSNPs), prepared MCs-loaded aged PSNPS (1, 5, 10, 15,
and 19 μg/mg), and systematically mapped the key molecular changes
induced by aged and MCs-loaded PSNPs to human hepatoblastoma (HepG2)
cells. According to the results, MC-LR adsorption is increased 2.64-fold
by aging, and PSNP accumulation is detected in HepG2 cells. The cytotoxicity
of the MC-LR-loaded aged PSNPs showed a positive relationship with
the MC-LR amount, as the cell viability in the 19 μg/mg loading
treatment (aPS-MC19) was 10.84% lower than aged PSNPs; meanwhile,
more severe oxidative damage was observed. Primary approaches involved
stressing the endoplasmic reticulum and reducing protein synthesis
that the aged PSNPs posed for HepG2 cells, while the aggravated cytotoxicity
in aPS-MC19 treatment was a combined result of the metabolic energy
disorder, oxidative damage, endoplasmic reticulum stress, and downregulation
of the MC-LR target protein. Our results confirm that the aged PSNPs
could bring more MC-LR into the HepG2 cells, significantly interfere
with biological processes, and provide new insight into deciphering
the risk of NPs to humans.