Ultrafine titanium dioxide nanoparticles induce cell death in human bronchial epithelial cells

Abstract

Titanium dioxide (TiO2) nanoparticles (TNPs), once perceived as harmless, have been shown to induce cytotoxicity on various cell types under UV radiation. However, whether TNPs elicit cell death in the absence of UV has not been thoroughly studied. This study aims to investigate the TNPs-induced cell death mechanism in UV-absent condition by examining the reduction of cell viability and apoptotic cell death characteristics in the human bronchial epithelial cell line, Chago-K1. The Chago-K1 cells were exposed to TNPs for 24 h at concentrations ranging from 0.1 to 2 mg mL-1. CCK-8 and Live/Dead assays demonstrating diminishing cell viability indicate that peak cell death occurred around 2 mg mL-1 TNPs after 24 h treatment in darkness. Apoptotic related cell death mechanisms were demonstrated by chromatin condensation and translocation of phosphatidylserine with Annexin V staining. Here we demonstrate that ultrafine TNPs (75 nm) in darkness can induce significant cytotoxicity on the Chago-K1 cells possibly through apoptotic pathways.