Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) have attracted a great
deal of attention due to their excellent electrical, optical, whitening, UV-adsorbing and bactericidal properties. The extensive production and utilization of these NPs increases their chances of being released into the environment and conferring unintended biological effects upon exposure. With the increasingly prevalent use of the omics technique, new data are burgeoning which provide a global view on the overall changes induced by exposures to NPs. In this review, we provide an account of the biological effects of ZnO and TiO2 NPs arising from transcriptomics in in vivo and in vitro studies. In addition to studies on humans and mice, we also describe findings on ecotoxicology-related species, such as Danio rerio (zebrafish), Caenorhabditis elegans (nematode) or Arabidopsis thaliana (thale cress). Based on evidence from transcriptomics studies, we discuss particle-induced biological effects,
including cytotoxicity, developmental alterations and immune responses, that are ependent on both material-intrinsic and acquired/transformed properties. This review seeks to provide a holistic insight into the global changes induced by ZnO and TiO2 NPs pertinent to human and ecotoxicology.
Transcriptomic studies enable us to better track, compare and conclude the shared and design” of NPs for wider uses in human society. Research on contrasting the differential effects of ZnO or TiO2 NPs in healthy versus immunocompromised organisms is warranted for evaluating the risk of exposures for vulnerable populations particle-specific effects.