Polystyrene nanoparticles: the mechanism of their genotoxicity in human peripheral blood mononuclear cells

Figures & data

Figure 1. DLS size distribution by the volume of A, B, and C PS-NPs.

Table 1. The size of PS-NPs obtained by measurement with DLS, AFM, and SEM techniques.

PS NPs	(nm)	(nm)	(nm)
manufacturer	29	44	72
AFM	∼ 24	∼ 41	∼ 72
SEM	26 ± 4	40 ± 5	70 ± 4
DLS in water	30 ± 7	40 ± 9	72 ± 17
DLS in RPMI	95 ± 4	60 ± 5	63 ± 5
Peak 1	179 ± 13	49 ± 3	61 ± 3
Peak 2	28 ± 2	1953 ± 3040	–
Peak 3	4576 ± 759	–	–

Figure 2. AFM images and corresponding cross-sectional profiles of selected PS-NPs.

Figure 3. SEM images of nanostructures built of PS-NPs of different sizes (left column). PS-NPs size distribution (right column).

Table 2. The level of ζ-potential of PS-NPs in water and in cell medium (RPMI), pH 7.4.

PS NPs	(nm)	(nm)	(nm)
manufacturer	29	44	72
ζ-potential in water (mV)	–40 ± 1	–38 ± 1	–36 ± 1
ζ-potential in RPMI (mV)	–41 ± 3	–45 ± 2	–56 ± 2

Figure 4. The level of metabolic activity of human PBMCs incubated with PS-NPs of 29, 44, and 72 nm in diameter in the range of concentrations of 10–1000 µg/mL for 24 h. Statistically significant changes for p < 0.05* (n = 5).

Figure 5. The level of DNA strand-breaks in human PBMCs incubated for 24 h with PS-NPs of 29, 44, and 72 nm in diameter in the range of concentrations of 0.0001-100 µg/mL. Statistically significant changes for p < 0.05* (n = 5).

Figure 6. Selected photos showing the level of single and double strand-breaks (DNA in comet tail) in human PBMCs incubated for 24 h with PS-NPs of 29, 44, and 72 nm in diameter at two selected concentrations of 0.001 and 100 µg/mL versus the control. Photos were taken with a Zeiss Axio Scope. A1 fluorescence microscope.

Figure 7. The level of DNA double strand-breaks in human PBMCs incubated for 24 h with PS-NPs of 29, 44, and 72 nm in diameter in the range of concentrations of 0.0001–100 µg/mL. Statistically significant changes for p < 0.05* (n = 5).

Figure 8. The level of DNA purines oxidation in human PBMCs (analysis by means of alkaline version of the comet assay with formamidopyrimidine-DNA glycosylase). The cells were incubated for 24 h with PS-NPs of 29, 44, and 72 nm in diameter in the range of concentrations of 0.0001–100 µg/mL. The value of comet tail (damaged DNA) in the presence of either enzyme for different concentrations of PS-NPs was reduced by the value obtained in comet assay without the enzyme (value for enzymatic buffer for the appropriate concentration of PS-NPs). Statistically significant changes for p < 0.05* (n = 5).

Figure 9. The level of DNA pyrimidines oxidation in human PBMCs (analysis by means of alkaline version of the comet assay with endonuclease III). PBMCs were incubated for 24 h with PS-NPs of 29, 44, and 72 nm in diameter in the range of concentrations of 0.0001–100 µg/mL. The value of comet tail (damaged DNA) in the presence of either enzyme for different concentrations of PS-NPs was reduced by the value obtained in comet assay without the enzyme (value for enzymatic buffer for the appropriate concentration of PS-NPs). Statistically significant changes for p < 0.05* (n = 5).

Figure 10. The level of 8-oxodG in human PBMCs. PBMCs were incubated for 24 h with PS-NPs of 29, 44, and 72 nm in diameter in the range of concentrations of 0.0001–100 µg/mL. Statistically significant changes for p < 0.05* (n = 3).

Figure 11. Time course of the repair kinetics of DNA damage (SSBs and DSBs), measured as DNA in comet tail of PBMCs treated for 24 h with PS-NPs of 29, 44, and 72 nm in diameter in the concentration of 100 μg/mL, and then post-incubated for 2 h in medium deprived of tested particles. (*) Statistically significant different from control (p < 0.05). (#) Statistically significant different from time "0" for individual PS-NPs size (p < 0.05). Each value represents the mean ± SD (n = 5).