TiO2 nanoparticles and TiO2 nanoparticles surface modified with salicylic acid affect neurological functions and oxidative stress markers in the eyes of adult rats

Titanium dioxide nanoparticles (TiO2NPs) are widely used in pharmaceutics, food products and cosmetics. Besides numerous beneficial outcomes, they also induce toxic effects in different organs, including the eyes. The recent findings report that some surface modifications can attenuate TiO2NPs toxicity. Thus, the aim of this study was to compare the effects of acute oral treatment with commercially available, bare TiO2NPs and TiO2NPs surface modified with salicylic acid (SA-TiO2NPs) using adult Wistar rats as model organisms. Control animals were gastrically intubated with vehicle (0.01 M HCl), while others were treated with either TiO2NPs or SA-TiO2NPs (1000mg/kg dissolved in vehicle). Afterward, the mortality rate as the acute toxicity parameter and parameters of neurological function were assessed. Animals were sacrificed on the 14th day following treatment. In the eye crude synaptosomal fraction, the effects of treatments on oxidative stress markers such as prooxidant/antioxidant balance (PAB) and lipid peroxidation (LPO) were compared. According to the obtained results, the mortality was 0 in all experimental groups. TiO2NPs and SA-TiO2NPs treatments displayed mild effects on spontaneous activity and pacing and had no impact on the visual placing reflex. Moreover, TiO2NPs and SA-TiO2NPs exposure significantly elevated PAB levels, when compared to controls. Animals treated with SA-TiO2NPs had similar LPO levels as controls, while in TiO2NPs group LPO levels were significantly increased. The presented data showed that both examined nanoparticles exerted similar outcomes referring to most of the investigated parameters, however, surface binding of SA decreased the level of LPO and thus, mitigated some of TiO2NPs toxicity in the eyes.