Important Factors Affecting Induction of Cell Death, Oxidative Stress and DNA Damage by Nano- and Microplastic Particles In Vitro.

We have described the influence of selected factors that increase the toxicity of nanoplastics (NPs) and microplastics (MPs) with regard to cell viability, various types of cell death, reactive oxygen species (ROS) induction, and genotoxicity. These factors include plastic particle size (NPs/MPs), zeta potential, exposure time, concentration, functionalization, and the influence of environmental factors and cell type. Studies have unequivocally shown that smaller plastic particles are more cytotoxic, penetrate cells more easily, increase ROS formation, and induce oxidative damage to proteins, lipids, and DNA. The toxic effects also increase with concentration and incubation time. NPs with positive zeta potential are also more toxic than those with a negative zeta potential because the cells are negatively charged, inducing stronger interactions. The deleterious effects of NPs and MPs are increased by functionalization with anionic or carboxyl groups, due to greater interaction with cell membrane components. Cationic NPs/MPs are particularly toxic due to their greater cellular uptake and/or their effects on cells and lysosomal membranes. The effects of polystyrene (PS) vary from one cell type to another, and normal cells are more sensitive to NPs than cancerous ones. The toxicity of NPs/MPs can be enhanced by environmental factors, including UV radiation, as they cause the particles to shrink and change their shape, which is a particularly important consideration when working with environmentally-changed NPs/MPs. In summary, the cytotoxicity, oxidative properties, and genotoxicity of plastic particles depends on their concentration, duration of action, and cell type. Also, NPs/MPs with a smaller diameter and positive zeta potential, and those exposed to UV and functionalized with amino groups, demonstrate higher toxicity than larger, non-functionalized and environmentally-unchanged particles with a negative zeta potential.

The effects of non-functionalized polystyrene nanoparticles with different diameters on human erythrocyte membrane and morphology.

In this study, the potential toxicity of non-functionalized polystyrene nanoparticles (PS-NPs) in human erythrocytes has been assessed. The effect of PS-NPs with different diameters (∼30 nm, ∼45 nm, ∼70 nm) on fluidity of erythrocytes membrane, red blood cells shape, as well as haemolysis of these cells has been investigated. Erythrocytes were incubated for 24 h with non-functionalized PS-NPs in concentrations ranging from 0.001 to 200 µg/mL in order to study haemolysis and from 0.001 to 10 µg/mL to determine other parameters. Fluidity was estimated by electron paramagnetic resonance (EPR) and the fluorimetric method. It has been shown that PS-NPs induced haemolysis, caused changes in the fluidity of red blood cells membrane, and altered their shape. Non-functionalized PS-NPs increased the membrane stiffness in the hydrophobic region of hydrocarbon chains of fatty acids. The observed changes in haemolysis and morphology were dependent on the size of the nanoparticles. The smallest PS-NPs of ∼30 nm (with the smallest absolute value of the negative zeta potential -29.68 mV) induced the greatest haemolysis, while the largest PS-NPs of ∼70 nm (with the highest absolute value of the negative zeta potential -42.00 mV) caused the greatest changes in erythrocyte shape and stomatocytes formation.