Effect of size and shape on toxicity of ZnO and TiO2 nanomaterials

Abstract

Engineered metal oxide nanomaterials like ZnO and TiO2 are mass produced and widely used in industrial, chemical, biomedical and agricultural applications, which increases people s exposure. Besides chemical composition, the role of other particle parameters like size and shape in toxicity induction has been studied in detailed in the thesis. Four different ZnO NMs (NPs, NRs, MPs, and MRs) and three different TiO2 NMs (NP, NR and NF) were prepared and used in the study. Toxicological studies of ZnO NMs were conducted in HPBL cells. In HPBL larger MPs and MRs were more cytotoxic than smaller NPs and NRs due to more physical insult caused by larger MPs and MRs through ROS. ROS directly or indirectly depletes cellular GSH and promotes free radical species formation and leads to cellular damage proteins and DNA. Smaller NPs and NRs appear to be more genotoxic than larger MPs and MRs. The cytotoxicity and genotoxicity of ZnO NPs are due to dissolution of Zn ions. NPs and NRs induce high level of oxidative potential and ROS generation as indicated by DTT and DCF assays. Larger ZnO MPs and MRs treatment had higher levels of lipid peroxidation markers (TBARs and LOOH) and caused significant damage to cells. Anti-oxidants like Vitamin C or Quercetin reverses DNA damage. The up-regulation of genotoxicity by Apocynin is contrasting to other anti-oxidants used in the study. newline