Combination of humic acid and clay reduce the ecotoxic effect of TiO2 NPs: A combined physico-chemical and genetic study using zebrafish embryo

Abstract The series of breakthroughs that have occurred within the realm of nanotechnology have been the source of several new products and technological interventions. One of the most salient examples in this regard is the widespread employment of titanium dioxide (TiO2) nanoparticles across a range of consumer goods. Given that waste is generated at every stage of the consumer-product cycle (from production to disposal), many items with TiO2 nanoparticles are likely to end up being discarded into water bodies. In order to understand the interaction of TiO2 NPs with aquatic ecosystem, the ecological fate and toxicity of TiO2 NPs was studied by exposing zebrafish embryos to a combination of abiotic factors (humic acid and clay) to assess its effect on the development of zebrafish embryos. The physiological changes were correlated with genetic marker analysis to holistically understand the effect on embryos development. Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was used to analyze the interaction energy between TiO2 NPs and natural organic matter (NOM) for understanding the aggregation behavior of engineered nanoparticles (ENPs) in media. The study revealed that combination of HA and clay stabilized TiO2 NPs compared to bare TiO2 and HA or clay alone. TiO2 NPs and TiO2 NPs + Clay significantly altered the expression of genes involved in development of dorsoventral axis and neural network of zebrafish embryos. However, the presence of HA and HA + clay showed protective effect on zebrafish embryo development. The complete system analysis presented shows the possible ameliorating effects of abiotic factors on the ecotoxicity of ENPs.