Uptake and intracellular localization of submicron and nano-sized SiO2 particles in HeLa cells

Abstract

Engineered amorphous silica nanoparticles (SiO(2)-NPs) are widely used in dyes, varnishes, plastics and glue, as well as in pharmaceuticals, cosmetics and food. Novel composite SiO(2)-NPs are promising multifunctional devices and combine labels for subsequent tracking and are functionalized e.g. to specifically target cells to deliver their cargo. However, biological and potential toxic effects of SiO(2)-NPs are insufficiently understood. The aim of this study was to determine the uptake and fate of SiO(2)-NPs in mammalian cells. Also, silica submicron particles (SiO(2)-SMPs) were included in the studies in order to identify effects, which are only observed for nano-sized SiO(2) particles. Fluorescently labelled SiO(2)-NPs (nominal size 70 nm) and SiO(2)-SMPs (nominal size 200 and 500 nm) were used to examine cytotoxicity, cellular uptake and localization in human cervical carcinoma cells (HeLa). Particle uptake and intracellular localization in mitochondria, endosomes, lysosomes and nuclei were studied by wide field and confocal laser scanning fluorescence microscopy. Physicochemical characterization of SiO(2)-NPs by transmission electron microscopy and dynamic light scattering revealed a spherical morphology and a monodisperse size distribution. In the presence of serum, all SiO(2) particles are non-toxic. However, in the absence of serum SiO(2)-NPs but not SiO(2)-SMPs are highly toxic. SiO(2) particles, irrespective of size, were detected in the cytosol and accumulated in endosomal compartments of HeLa cells. No accumulation of SiO(2) particles in nuclei or mitochondria of HeLa cells could be observed. In contrast to SiO(2)-SMPs, SiO(2)-NPs are preferentially localized in lysosomes.

Lysosomal Dysfunction Caused by Cellular Accumulation of Silica Nanoparticles

“…2, A and B). No colocalization of internalized SiNPs with the Golgi complex, mitochondria, or the endoplasmic reticulum was detected (data not shown), in agreement with Al-Rawi et al (27). The accumulation of SiNPs in late endosomes/lysosomes was also observed in living cells incubated with LysoTracker Red (Fig.…”

Semi‐quantitative estimation of cellular SiO2nanoparticles using flow cytometry combined with X‐ray fluorescence measurements

“…As previously mentioned, this is due to the good colloidal stability the SiO 2 NP dispersion in cell culture media during the exposure periods. Similarly, SiO 2 NPs with core sizes of 70, 200, and 500 nm were reported as nontoxic to HeLa cells in the presence of serum (22,23), which is in good agreement with the observation in this study. Thus, for these (6) SiO 2 30 , (6) SiO 2 200 , and (6) SiO 2 300 NPs, these nontoxic conditions (exposure time: 3 h, dose: 0-500 lg/mL) were chosen for the following FCM, TEM, and XRF experiments.…”

“…In addition, as can be seen in Figures 5 and 6, the SiO 2 NPs were not found in the cell nucleus under any of the conditions tested (i.e., different size and surface charge), which is in good agreement with the previous reports. Al-Rawi et al reported that 300 nm SiO 2 NPs were observed in lysosomes and cytoplasm but not in the nucleus, and fluorescence microscopy study with fluorescent-SiO 2 showed no evidence of nuclear translocalization (22,26).…”

Nanoparticle Technology as a Double-Edged Sword: Cytotoxic, Genotoxic and Epigenetic Effects on Living Cells

“…QDs which could not enter nuclear membrane is localized only inside cytosol membrane [35]. The same nanoparticles such as silica nanoparticles (SiO 2 ) with diverse type of energy transfer cassettes can localize in different organelles [36]. The interactions between specific nanoparticles and organelles and the effect triggered by such interactions are presented in Table 2.…”