Mechanistic insight into ROS and neutral lipid alteration induced toxicity in the human model with fins (Danio rerio) by industrially synthesized titanium dioxide nanoparticles.

The toxicological impact of TiO2 nanoparticles on the environment and human health has been extensively studied in the last few decades, but the mechanistic details were unknown. In this study, we evaluated the impact of industrially prepared TiO2 nanoparticles on the biological system using zebrafish embryo as an in vivo model. The industrial synthesis of TiO2 nanoparticles was mimicked on the lab scale using the high energy ball milling (HEBM) method by milling bulk TiO2 particles for 5 h, 10 h, and 15 h in an ambient environment. The physiochemical properties were characterized by standard methods like field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS), X-ray diffraction (XRD) and UV-Visible spectroscopy. In vivo cytotoxicity was assessed on zebrafish embryos by the evaluation of their mortality rate and hatching rate. Experimental and computational analysis of reactive oxygen species (ROS) induction, apoptosis, and neutral lipid alteration was done to study the effects on the cellular level of zebrafish larvae. The analysis depicted the change in size and surface charge of TiO2 nanoparticles with respect to the increase in milling time. In silico investigations revealed the significant role of ROS quenching and altered neutral lipid accumulation functionalised by the molecular interaction of respective metabolic proteins in the cytotoxicity of TiO2 nanoparticles with zebrafish embryos. The results reveal the hidden effect of industrially synthesized TiO2 nanoparticle exposure on the alteration of lipid accumulation and ROS in developing zebrafish embryos. Moreover, the assessment provided a detailed mechanistic analysis of in vivo cytotoxicity at the molecular level.