Silica nanoparticles (SiNPs) are one of the most commonly used nanomaterials in various medical applications. However, possible mechanisms of the toxicity caused by SiNPs remain unclear. The study presented here provides novel information on molecular and cellular effects of SiNPs in glioblastoma LBC3 and LN-18 cells. It has been demonstrated that SiNPs of 7 nm, 5–15 nm and 10–20 nm induce time- and dose-dependent cytotoxicity in LBC3 and LN-18 cell lines. In contrast to glioblastoma cells, we observed only weak reduction in viability of normal skin fibroblasts treated with SiNPs. Furthermore, in LBC3 cells treated with 5–15 nm SiNPs we noticed induction of apoptosis and necrosis, while in LN-18 cells only necrosis. The 5–15 nm SiNPs were also found to cause oxidative stress, a loss in mitochondrial membrane potential, and changes in the ultrastructure of the mitochondria in LBC3 cells. Quantitative real-time PCR results showed that in LBC3 cells the mRNA levels of pro-apoptotic genes Bim, Bax, Puma, and Noxa were significantly upregulated. An increase in activity of caspase-9 in these cells was also observed. Moreover, the activation of SiNP-induced autophagy was demonstrated in LBC3 cells as shown by an increase in LC3-II/LC3-I ratio, the upregulation of Atg5 gene and an increase in AVOs-positive cells. In conclusion, this research provides novel information concerning molecular mechanisms of apoptosis and autophagy in LBC3 cells.
The effect has been studied of the adsorption of ions (H(+), Na(+), OH(-), Cl(-)) which are present in solution upon the electric charge of the liposome membrane formed of phosphatidylcholine (PC). The surface charge density of the membrane was determined as a function of pH and electrolyte concentration from electrophoretic mobility measurements. The measurements were carried out by the laser-Doppler microelectrophoresis method. A four-equilibria model has been proposed to describe the phenomena occurring on the membrane surface. The equilibria in which the adsorption of other ions on the liposome membrane surface was involved were assumed to exist beside the equilibria in which the H(+) and OH(-) ions were engaged. The idea was confirmed by mathematical calculations. Association constants of the liposome membrane surface with ions of solution (K(AH), K(ANa), K(BOH), K(BCl)) were determined. The proposed model has been proved to be correct by comparing the resulting theoretic charge variation curves of the lecithin membrane with the experimental data.
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