TiO₂ nanoparticles induce omphalocele in chicken embryo by disrupting Wnt signaling pathway

Titanium dioxide nanoparticles (TiO₂ NPs) are among abundantly used metal oxide NPs but their interactions with biomolecules and subsequent embryonic toxicity in higher vertebrates is not extensively reported. Physicochemical interactions of TiO₂ NPs with egg albumen reveals that lower doses of TiO₂ NPs (10 and 25 µg/ml) accounted for higher friccohesity and activation energy but an increment in molecular radii was recorded at higher doses (50 and 100 µg/ml). FTIR analysis revealed conformational changes in secondary structure of egg albumen as a result of electrostratic interactions between egg albumen and TiO₂ NPs. The morphometric data of chicken embryo recorded a reduction at all the doses of TiO₂ NPs, but toxicity and developmental deformity (omphalocele and flexed limbs) were recorded at lower doses only. Inductively coupled plasma optical emission spectrometry (ICP-OES) confirmed presence of Ti in chicken embryos. mRNA levels of genes involved in canonical and non-canonical Wnt signaling were lowered following TiO₂ NPs treatment resulting in free radical mediated disruption of lateral plate mesoderm and somite myogenesis. Conformational changes in egg albumen and subsequent developmental deformity in chicken embryo following TiO₂ NPs treatment warrants detailed studies of NP toxicity at lower doses prior to their biomedical applications.