Could Iron-Nitrogen Doping Modulate the Cytotoxicity of TiO2 Nanoparticles?

Abstract

Titanium dioxide nanoparticles (TiO2 NPs) are found in several products on the market that include paints, smart textiles, cosmetics and food products. Besides these, TiO2 NPs are intensively researched for their use in biomedicine, agriculture or installations to produce energy. Taking into account that several risks have been associated with the use of TiO2 NPs, our aim was to provide TiO2 NPs with improved qualities and lower toxicity to humans and the environment. Pure TiO2 P25 NPs and the same NPs co-doped with iron (1%) and nitrogen atoms (P25-Fe(1%)-N NPs) by hydrothermal treatment to increase the photocatalytic activity in the visible light spectrum were in vitro evaluated in the presence of human lung cells. After 24 and 72 h of incubation, the oxidative stress was initiated in a time- and dose-dependent manner with major differences between pure P25 and P25-Fe(1%)-N NPs as revealed by malondialdehyde and reactive oxygen species levels. Additionally, a lower dynamic of autophagic vacuoles formation was observed in cells exposed to Fe-N-doped P25 NPs compared to the pure ones. Therefore, our results suggest that Fe-N doping of TiO2 NPs can represent a valuable alternative to the conventional P25 Degussa particles in industrial and medical applications.

MRC-5 Human Lung Fibroblasts Alleviate the Genotoxic Effect of Fe-N Co-Doped Titanium Dioxide Nanoparticles through an OGG1/2-Dependent Reparatory Mechanism

“…The levels of 8-OHdG induced by both doses of P25-Fe(1%)-N NPs and the dose of 10 µg/mL non-doped P25 NPs were generally similar and have not exceeded 130% compared to control after 72 h of exposure. However, the higher dose of P25 NPs caused an increase of the level of 8-OHdG up to 235% compared to the control after MRC-5 cells were exposed for 24 h. Also, 8-OHdG concentration was lowered in the cells as time passed, reaching 166% compared to the control at 72 h. Interestingly, the reduction of 8-OHdG recorded at 72 h at 50 µg/mL P25 NPs contrasts with the high level of ROS measured previously by us in MRC-5 cells [ 76 ].…”

“…The concentrations of NPs, i.e., 10 µg/mL and 50 µg/mL, respectively, used by us were chosen based on our previous work [ 76 ] in which we proved that P25 NPs could cause a significant increase of oxidative stress in MRC-5 cells in a time- and dose-dependent manner while P25-Fe(1%)-N NPs had no influence on ROS level compared to the control group of cells.…”

“…In our previous work [ 76 ], we already showed the significant difference between the ability of P25 and P25-Fe(1%)-N NPs to produce ROS. While P25 NPs could induce high levels of ROS in a time and dose-dependent manner, doping with iron ions totally suppressed the generation of oxidative stress [ 76 ]. Similarly, iron doping inhibited the production of TiO 2 -induced ROS in HaCaT keratinocytes [ 64 ].…”

“…Therefore, we compared the toxicity of P25 TiO 2 NPs doped with iron and nitrogen with the same undoped NPs. The doses used by us were based on our previously published work [ 76 ] as well as on representative papers [ 80 , 81 , 82 , 83 ].…”

“…Moreover, our previous paper [ 76 ] investigated the effect of TiO 2 NPs on the enzymatic antioxidant mechanism of MRC-5 cells. When the ROS level exceeded the neutralizing ability of antioxidant enzymes, some of the free radicals began to impair intracellular biomolecules.…”