Nano titanium exposure induces dose- and size-dependent cytotoxicity on human epithelial lung and colon cells.

The productions as well as use of Titanium dioxide nanoparticles (TNPs) were rapidly increasing in the present nano-world. The TNP becomes an inevitable part our daily life in the form of cosmeceutical, bio-medical, and nano-pharmaceutical applications. The TNPs are either inhaled or ingested into the human body through common routes of exposure like the lungs and the oral-gastrointestinal tract (GIT). Human lung and colon were exposed to test particles, TNP 18 nm (TNP 18), TNP 30 nm (TNP 30), and TNP 87 nm (TNP 87) with a dose range 0.1-100 µg/ml. The effect of exposure was determined using MTT, LDH, and DCFH-DA methods. The TNP 18, TNP 30, and TNP 87 significantly (p < 0.001) reduced cell viability in a dose- and a size-dependent manner in 60 and 100 µg/ml. The lowest IC50 values 21.80 and 24.83 µg/ml were observed in A549 and Caco-2 for the smallest size, TNP 18. Further, for TNP 30, IC50 values were 23.30 and 28.59 µg/ml compared to Nano QTZ 43.82 and 45.86 µg/ml. The EC25 values of LDH leakage were 5.83 and 9.50 µg/ml for TNP 18 in lung and colon cells. Besides, ROS levels increased significantly at doses 60 (p < 0.01) and 100 (p < 0.001) µg/ml in two cells. The smaller size particle, TNP 18 has produced a significant (p < 0.05) toxic effect at the lowest dose i.e., 10 µg/ml. Therefore, we conclude that TNP 18, TNP 30, and TNP 87 induced a dose- and size-dependent cytotoxicity via decreased cell viability, increased LDH and ROS levels by in vitro methods.