Figure 2.

Morphological changes and normalized IR spectra of primary cultures of astrocytes exposed to SiO₂-NPs. (a) Astrocyte morphology after 24 h of SiO₂-NPs exposure. Images were obtained by light microscopy. Each treatment was performed at least in triplicate (n = 3) with three technical replicates. Subtle morphological changes compared to control culture are appreciated at 1, 10, and 25 µg/mL SiO₂-NPs. At 50 µg/mL and 100 µg/mL SiO₂-NPs, the size and amount of the astrocytes decreased markedly in comparison with the control. Scale bar: 150 µm. (b) Normalized IR spectra of astrocytes exposed to SiO₂-NPs. The spectral region of 960–1280 cm⁻¹ corresponds to PO₂- (nucleic acids) and SiO₂-NPs; 1500–1800 cm⁻¹ is the spectral region that contains the amide I spectral bands and representative bands of the secondary protein structure; 2830–3000 cm⁻¹ includes the spectral bands of symmetric lipid CH₂ and asymmetric CH₂. The spectral images are representative of four independent experiments performed with each treatment, with three technical replicates.