Silica nanoparticles (SNPs) are one of the most important nanomaterials, and

Silica nanoparticles (SNPs) are one of the most important nanomaterials, and have been widely used in a variety of fields. mitochondrial damage on flow cytometry and confocal microscopy, which might have led to failure of cytokinesis in these cells. Further, SNPs inhibited cell growth and induced apoptosis in uncovered cells. Taken together, our findings demonstrate that multinucleation in L-02 human hepatic cells might Evofosfamide be Evofosfamide a failure to undergo cytokinesis or cell fusion in response to SNPs, and the increase in cellular reactive oxygen species could be responsible for the apoptosis seen in both mononuclear cells and multinucleated cells. < 0.05 was considered to be statistically significant. Results Characterization of SNPs Transmission electron microscopy showed that the amorphous SNPs were uniform in Evofosfamide size and evenly distributed with good monodispersity and a spherical shape (Physique 1). The average size of these nanoparticles was 53 5.1 nm, which was determined by measuring 300 particles with ImageJ software (National Institutes of Health, Bethesda, MD, USA). The purity of the amorphous SNPs was higher than 99.9%. Their hydrodynamic diameter and zeta potential were assessed in distilled water as the stock medium and in RMPI 1640 as the exposure medium at 0, 3, 6, and 24 hours to reflect their dispersion throughout the experiments. As shown in Table 1, the hydrodynamic diameter of these particles was about 90 nm and did not change significantly with time. Zeta potential measurement showed that the SNPs were highly negatively charged (about ?30 mV), indicating a fairly stable suspension in both types of dispersion medium. Physique 1 Transmission electron microscopic image of 53 nm amorphous silica nanoparticles. Table 1 Time evolution of the hydrodynamic diameter and zeta potential of 53 nm silica nanoparticles in different dispersion medium Cell viability After exposure of the cells to various concentrations of SNPs for 24 hours, cytotoxicity was estimated using a CCK-8 kit. As shown in Physique 2, the L-02 cell survival rate decreased with increasing silica exposure. Cell viability in the groups treated with 50, 100, 150, and 200 g/mL SNPs decreased to 71.32%, 54.42%, 40.66%, and 31.89%, respectively. Significant differences in cell viability were seen between the group treated with 50 g/mL SNPs and the control group after exposure (< 0.05). Evofosfamide Physique 2 Viability of L-02 cells treated with different concentrations of silica nanoparticles for 24 hours. The results indicate that viability is usually reduced in a dose-dependent manner. Data are expressed as the mean standard deviation of three impartial … Cell multinucleation Physique 3 shows the results of a representative multinucleation experiment in which L-02 cells were incubated with 100 g/mL SNPs for 24 hours. The use of Hoechst 33258 as a DNA labeling agent enabled determination of the DNA CIT content in all cells by measuring the integrated fluorescence emitted by each nucleus. Cells in the control group were normal with round and homogeneously stained nuclei, with only a few multinucleated cells observed, whereas giant cells made up of more than one nucleus were frequently observed upon exposure to different concentrations of SNPs, suggesting that these cells had become multinucleated. Multinucleation increased in a concentration-dependent manner, increasing from 1.6% in the control group to 19.2% in the group treated with 150 g/mL SNPs, and decreasing slightly to 12.6% in the group treated with 200 g/mL SNPs (Table 2). Physique 3 Multinucleation in L-02 cells induced by silica nanoparticles. (A) Control group and (W) group treated with100 g/mL silica nanoparticles. The cell nucleus and cytoplasm were stained by Hoechst 33258 and fluorescein diacetate, respectively. Binucleated … Table 2 Number of binucleated and multinucleated cells induced by silica nanoparticles Arrest of cell cycle To investigate the basis for multinucleation further, we examined cell cycle progression by flow cytometry. Arrest of the cell cycle was observed in all four treatment groups (Physique 4). As the silica dose increased, the percentage Evofosfamide of cells in G0/G1 phase gradually decreased, whereas the percentage of cells in G2/M phase increased significantly compared with the control group (< 0.05). This arrest of G2/M phase corresponded to an increase in the number of multinucleated cells observed.