Figure 4.

The effect on NO and ROS production of SiO₂ NPs fed to mice.

Notes: C57BL/6 mice were treated with varying sizes (20 nm, 100 nm) and charges (SiO₂^EN(R); negative, SiO₂^EN(−)) of 750 mg/kg colloidal SiO₂ NPs for 14 days. The supernatant of splenocytes from mice were harvested and (A) NO₂⁻ accumulation was assessed using the Griess colorimetric assay according to manufacturer’s instructions (Promega Corporation, Fitchburg, WI, USA), and (B) intracellular ROS accumulation was detected by fluorescent probe 2′,7′-dichlorodihydrofluorescein diacetate using a fluorescence microplate reader. Data are presented as the mean ± standard deviation; n=5. *P<0.05, and **P<0.01 indicate significant differences when tested with ANOVA. Tukey’s test was used for post hoc tests.

Abbreviations: NC, normal control; SiO₂, silicon dioxide; SiO₂^EN(−), negatively charged silicon dioxide; SiO₂^EN(R), silicon dioxide modified with L-arginine; NP, nanoparticle; NO, nitric oxide; ROS, reactive oxygen species; NO₂⁻, nitrate; n, number; ANOVA, analysis of variance.