Titanium Dioxide Nanoparticles As Guardian against Environmental Carcinogen Benzo[alpha]Pyrene

Abstract

Polycyclic aromatic hydrocarbons (PAH), like Benzo[alpha]Pyrene (BaP) are known to cause a number of toxic manifestations including lung cancer. As Titanium dioxide Nanoparticles (TiO 2 NPs) have recently been shown to adsorb a number of PAHs from soil and water, we investigated whether TiO 2 NPs could provide protection against the BaP induced toxicity in biological system. A549 cells when co-exposed with BaP (25 mM, 50 mM and 75 mM) along with 0.1 mg/ml,0.5 mg/ml and 1 mg/ml of TiO 2 NPs, showed significant reduction in the toxic effects of BaP, as measured by Micronucleus Assay, MTT Assay and ROS Assay. In order to explore the mechanism of protection by TiO 2 NP against BaP, we performed in silico studies. BaP and other PAHs are known to enter the cell via aromatic hydrocarbon receptor (AHR). TiO 2 NP showed a much higher docking score with AHR (12074) as compared to the docking score of BaP with AHR (4600). This indicates a preferential binding of TiO 2 NP with the AHR, in case if both the TiO 2 NP and BaP are present. Further, we have done the docking of BaP with the TiO 2 NP bound AHR-complex (score 4710), and observed that BaP showed strong adsorption on TiO 2 NP itself, and not at its original binding site (at AHR). TiO 2 NPs thereby prevent the entry of BaP in to the cell via AHR and hence protect cells against the deleterious effects induced by BaP.