Titanium dioxide nanoparticles: an in vitro study of DNA binding, chromosome aberration assay, and comet assay

Abstract

Engineered titanium dioxide nanoparticles (TiO NPs) are extensively used in cosmetic, pharmaceutical and other industries globally due to their unique properties, which has raised concern for biosafety. Genotoxicity assessment is an important part of biosafety evaluation; we report in vitro cytogenetic assays for NPs considering their unique physicochemical characteristics to fill the gap of laboratory data regarding biological safety along with mechanistic study for mode of interaction of NP with genetic material. Comet and chromosome aberration assay (CA assay) using short-term human peripheral blood cultures following exposure to TiO NPs; along with physicochemical parameters for stability of nano form in cultures; and DNA binding activity were carried out. The dynamic light scattering and zeta potential measurements revealed mono dispersion in media. The fluorescence spectroscopy for binding affinity of TiO NPs and human genomic DNA showed binding constant (K), 4.158 × 10 M indicating strong binding affinity and negative ΔG value suggesting spontaneous DNA binding supporting its genotoxic potential. Following in vitro exposure to TiO NPs for 24 h, the cultures were analyzed for comet and CA assays, which showed significant results (p < 0.05) for % DNA intensity in tail, Olive Tail Moment and frequency of Chromosomal aberrations (CA) at 75 and 125 μM but not at 25 μM.

Genotoxicity of TiO2 Nanoparticles in Four Different Human Cell Lines (A549, HEPG2, A172 and SH-SY5Y)

“…In vitro, TiO 2 NPs have been shown to accumulate in cells mainly by endocytosis and to distribute in intracytoplasmic compartments [31,33,36,50,[54][55][56][57]. Some reports also indicated their presence in the nucleus of cells [27,29,60], but in small proportion compared with the observed amount in cytoplasmic compartments, making direct interaction between DNA and TiO 2 NPs unlikely. Moreover, Xu et al [61] reported that subcellular localization of nanoparticles plays a critical role in the toxicity profile, with lower toxicity when NPs are localized in the cytoplasm of cells and higher reactivity when nanoparticles are accumulated in nuclei and lysosomes.…”

“…According to a recent review on the genotoxic potential of TiO 2 nanoparticles, seven out of 24 comet assay studies (30%) and four out of 16 micronucleus (MN) test studies (25%) showed no increase in genotoxic damage following exposure to different types of TiO 2 NPs [26]. Positive findings have been associated with direct interaction with the DNA, after reaching the nucleus [7,[27][28][29][30], or indirect mechanisms that include induction of oxidative stress [30][31][32][33][34][35].…”

The Possible Protective Role of N-Acetyl Cysteine against Titanium Dioxide Nanoparticles Intestinal Toxicity in Adult Male Albino Rats

“…By using different cell lines, numerous studies showed the ability of TiO2 NPs in inducing genotoxicity (Landsiedel et al, 2009;Singh et al, 2009;Turkez, 2011;Catalán et al, 2012;Ghosh et al, 2013;Tavares et al, 2014;Khan et al, 2015 andPatel et al, 2017). Also, multiple in vivo studies showed genotoxicity induced by TiO2NPs (Trouiller et al, 2009;Mohamed andHussien, 2016 andEl-Sheikh et al, 2016).…”

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

“…The results of this in vitro study demonstrate that the exposure to TiO 2 NPs induced an increase in DNA strand breaks, a loss of DNA stability and apoptosis, as well as reduced cells viability, whereas the exposure to lincomycin itself had no toxic/genotoxic effects on amniotic cells. The authors suggested that the underlying molecular mechanism of the DNA damage may be the production of ROS by the NPs, notably the ● OH radical [ 50 , 53 ]. To date, researchers usually associate the genotoxicity of TiO 2 NPs with the formation of oxidants [ 54 , 55 , 56 , 57 , 58 , 59 ].…”