Pulmonary impact of titanium dioxide nanorods: examination of nanorod-exposed rat lungs and human alveolar cells

Abstract

BackgroundTitanium dioxide nanoparticles have numerous applications, resulting in human exposure. Nonetheless, available toxicological and safety data are insufficient regarding aspherical particles, such as rod-shaped nanoparticles.MethodsIn a combined in vitro–in vivo approach, cultured A549 lung alveolar adenocarcinoma cells were treated with approximately 15×65 nm TiO2 nanorod-containing medium, while young adult rats received the same substance by intratracheal instillation for 28 days in 5 and 18 mg/kg body-weight doses. Nanoparticle accumulation in the lungs and consequent oxidative stress, cell damage, and inflammation were assessed by biochemical and histopathological methods.ResultsTitanium was detected in tissue samples by single-particle inductively coupled plasma mass spectrometry. Nanoparticles were visualized inside cultured A549 cells, within pulmonary macrophages, and in hilar lymph nodes of the rats. A549 cells showed dose-dependent oxidative stress and lethality, and the observed nanoparticle-laden endosomes suggested deranged lysosomal function and possible autophagy. Strongly elevated Ti levels were measured in the lungs of nanorod-treated rats and moderately elevated levels in the blood of the animals. Numerous cytokines, indicating acute and also chronic inflammation, were identified in the lung samples of TiO2-exposed rodents.ConclusionSeveral signs of cell and tissue damage were detected in both the cultured alveolar cells and in treated rats’ lungs. Rod-shaped nanoparticulate TiO2 may consequently be more harmful than has generally been supposed. The occupational health risk suggested by the results calls for improved safety measures.

<p>Presence of Titanium and Toxic Effects Observed in Rat Lungs, Kidneys, and Central Nervous System in vivo and in Cultured Astrocytes in vitro on Exposure by Titanium Dioxide Nanorods</p>

“… 41 TEM and DLS were performed both on freshly made suspension and after 3 months of storage at room temperature to prove suspension stability. Details of preparation of the TiO 2 NPs and the suspension, and the characteristics of them, were published by Horváth et al 15 …”

“…14 In one of our previous studies, rod-shaped TiO 2 NPs induced several inflammatory cytokines in the lungs of rats exposed to the nanorods subacutely via the airways. 15 The kidneys, exerting the function of removing xenobiotics, showed oxidative stress, increased inflammation markers, as well as functional and histological damages due to tubular necrosis in rats treated orally with (unspecified) nano-TiO 2 . 16 In another study, lipid peroxidation, reduced antioxidant activity, and proximal tubular apoptosis has been observed in the kidneys of rats after oral administration of spherical TiO 2 NPs of <100 nm in size for 3 weeks.…”

“… 14 In one of our previous studies, rod-shaped TiO 2 NPs induced several inflammatory cytokines in the lungs of rats exposed to the nanorods subacutely via the airways. 15 …”

Silk Polymers and Nanoparticles: A Powerful Combination for the Design of Versatile Biomaterials

“…To avoid direct use of UV radiation, NP surface modifications can be made, resulting in a shift in light absorption enabling the use of a different light source (Ni et al, 2017 ; Ziental et al, 2020 ). TiO 2 NPs have been the subject of a vast literature regarding their toxicity, sometimes polemical (Horváth et al, 2018 ; Suzuki et al, 2020 ), and their interaction with proteins impacting cell behavior (Jayaram et al, 2017 ; Runa et al, 2017 ).…”

Titanium Dioxide Nanoparticles in Food and Personal Care Products—What Do We Know about Their Safety?

“…A comparison of P25 and food grade titania with TiO 2 -based bipyramids, rods and platelets indicated that only the food grade titania and platelets were genotoxic to human epithelial cells in vitro [ 32 ]. TiO 2 nanorods demonstrated a dose-dependent toxicity in alveolar adenocarcinoma cells in vitro but were not compared to differently shaped TiO 2 nanoparticles [ 33 ]. In the same study, the rats that inhaled the nanorods were found to exhibit tissue damage, acute and chronic lung inflammation, and increased levels of titanium were measured not only in lungs but also in the bloodstream.…”