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Objective: Nowadays, the use of SiO2-based nanoparticles in the treatment of ocular diseases has significantly increased. Nanoparticles (NPs) can easily penetrate biological membranes and interact with membrane components such as ion channels. SiO2 nanoparticles (SiO2 NPs) are one of the most common used NPs in health field. There are limited studies determining the effects of SiO2 NPs on the retinal cells. In this study, it was aimed to investigate the effect of SiO2 NPs on transient receptor potential canonical 1 (TRPC1) expression and intracellular basal calcium concentration in retinal pigment epithelial (RPE) cells. Methods: Cultured hARPE 19 cells were divided into four groups as control, 50 µg/mL SiO2, 100 µg/mL SiO2, and 150 µg/mL SiO2. All groups except control were incubated for 24 h with SiO2 NPs. Subsequently, the expression level of TRPC1 was assessed utilizing the real-time polymerase chain reaction (PCR) method. Basal intracellular calcium concentration [Ca2+]i was measured using confocal microscopy. Results and Discussion: Relative TRPC1 gene expression levels and basal [Ca2+]i decreased significantly in the SiO2 dose groups compared to control group. There was a significant correlation of relative channel expression level and basal [Ca2+]i. Conclusions: Our results show that SiO2 NPs reduce the expression of TRPC1 channels, leading to a decrease in basal [Ca2+]i. The decrease in [Ca2+]i is likely to affect calcium-related physiological processes in RPE cells. However, more investigations are required regarding this subject. [ABSTRACT FROM AUTHOR]

In recent years, the use of nanotechnology-based methods has become widespread in the treatment of ocular diseases. Silica nanoparticles (SiO 2 NPs) are most common used NPs in medical field due to their physicochemical properties. SiO 2 NPs can easily cross biological membranes and interact with basic biological structures, causing structural and functional changes in cells. In this study, it was aimed to investigate the dose dependent effect of SiO 2 NPs on retinal pigment epithelium (RPE) in vitro using electrobiophysical, biochemical and histological methods. A commercially purchased human RPE (hARPE-19) cell line was used in this study. Cells were divided into four groups as control, 50 μg/mL SiO 2 , 100 μg/mL SiO 2 and 150 μg/mL SiO 2 groups. Cell index, apoptotic activity, cell cycle and oxidative stress markers were measured in all groups. Findings in the present study showed that SiO 2 nanoparticles reduced cell proliferation, increased oxidative stress, apoptosis and arrest in the G 0 /G 1 phase of the cell cycle as dose dependent manner in ARPE-19 cells. In conclusion, SiO 2 exposure can induce cytotoxic effects in RPE cell line. The results of this study provide clues that exposure to SiO 2 nanoparticles may impair visual function and reduce quality of life. However, further studies are needed in this regard., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

In spite of their widespread use, toxicity of silica nanoparticles (SiO 2 NPs) to mammalian has not been extensively investigated. In the present study, it is aimed to investigate the effects and the mechanism of action of 20 nm sized SiO 2 NPs on isolated uterine smooth muscle. A total number of 84 preparations of uterine strips were used in the experiments. Study was designed as four groups: group I (control), group II (0.2 mM SiO 2 NPs), group III (0.4 mM SiO 2 NPs) and group IV (0.8 mM SiO 2 NPs). Spontaneous contractions were recorded using mechanical activity recording system. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA) levels were measured using the spectrophotometric methods. Apoptosis of the cells was detected using immunofluorescence staining assay. SiO 2 NP distribution and ultrastructural changes were determined by transmission electron microscopy. In groups II-IV, the frequency of contraction was significantly lower than that of the group I, whereas the contraction energy significantly decreased only in group IV. SOD and GSH-Px activities were significantly lower in experimental groups compared to the control group. MDA level and apoptotic cells were significantly higher in all SiO 2 groups compared to the control group. Numerous SiO 2 NPs in cytoplasm and connective tissue were observed in all dose groups. These findings showed that 20 nm sized SiO 2 NPs enter the connective tissue and cytoplasm of uterine muscle cells and cause oxidative stress and apoptosis leading to impaired uterine contractile activity.