The Influence of Hydroxyapatite Nanoparticle Morphology on Embryonic Development in a Zebrafish Exposure Model

Nanomaterials are used in many different industries such as cosmetics, food, clothing, and electronics. There is increasing concern that exposure to nanoparticles (NPs) during pregnancy can adversely affect fetal development. It is well known that the size, charge, and chemistry of a nanoparticle can modulate embryological development. The role that particle morphology plays on early development, however, is still widely unknown. The present study aims to investigate the effect of hydroxyapatite nanoparticle (HANP) morphology on embryological development in a zebrafish exposure model. Four distinct HANP morphologies (dots, long rods, sheets, and fibers) were fabricated and characterized. Zebrafish embryos were exposed to HANPs (0-100 mg/L), and viability and developmental deformities were evaluated for up to 5 days post-fertilization (dpf). Malformations such as pericardial edema and axial curvature were apparent in embryos as early as 1 dpf, following exposure to the dot and fiber particles, and developed in embryos by 3 dpf in the sheet and long rod particle groups. Minimal death was observed in response to dot, long rod, and sheet particles (≤25%), while fiber particles induced overwhelming toxicity (≤60%) after 1 dpf, and complete toxicity during all subsequent time points. Collectively, these results suggest that nanoparticle morphology can significantly impact embryological development and should be a required consideration when designing nanomaterials for commercial use.