Differential impact of pure and zinc-doped cerium oxide nanoparticles on mouse embryo development in vitro

Cerium oxide nanoparticles (CeO₂NPs) exhibit redox activity that may influence biological systems, while zinc plays an essential role in reproductive function. However, the combined effects of zinc-doped CeO₂NPs on early embryonic development remain unclear. This study evaluated the effects of pure and zinc-doped CeO₂NPs on in vitro fertilization (IVF) and early embryo development in mice, focusing on cleavage and blastocyst formation. A total of 144 superovulated SWR/J female mice were used to obtain 1833 oocytes for IVF. Fertilized oocytes were cultured in media supplemented with pure CeO₂NPs or Zn-doped CeO₂NPs (5%, 10%, and 20%) at concentrations of (0.01, 0.1, and 1 µg/ml). Embryo development was assessed based on cleavage and blastocyst rates. Cleavage was significantly influenced by nanoparticle formulation in a concentration-dependent manner. Pure CeO₂NPs at 0.1 µg/ml reduced cleavage rates compared with control group, whereas 5% Zn–CeO₂NPs improved cleavage under specific conditions. No consistent improvement was observed at higher zinc doping levels, and 20% Zn–CeO₂NPs showed reduced cleavage at 1 µg/ml. In contrast, blastocyst formation remained unaffected across all treatment groups. The effects of CeO₂NPs on early embryonic development are formulation-dependent rather than concentration-driven. 5% Zn–CeO₂NPs was associated with improved cleavage under specific conditions, whereas higher doping levels did not confer consistent benefit. The absence of differences at the blastocyst stage suggests that embryos successfully progressing through cleavage retain their developmental competence, highlighting the importance of nanoparticle design in assisted reproductive applications.