Evaluation of Magnetite Nanoparticle-Based Toxicity on Embryo–Larvae Stages of Zebrafish (Danio rerio)

Iron oxide nanoparticles (NPs) are extensively used in various biomedical applications due to their suitability as carriers of diagnostic and therapeutic agents. Herein, we report on the evaluation of concentration-dependent toxicity studies of iron oxide (magnetite) NPs in zebrafish (Danio rerio). To follow the update of iron oxide NPs in the animal model, particles were functionalized by conjugating a fluorescent dye (Congo red) that serves as an efficient probe to track the uptake and accumulations of nanoparticles from the early life stages of zebrafish. As in vivo model organism to study the diffusion an in vivo toxicity, zebrafish embryos and larvae were treated with different concentrations of CR@Fe3O4 conjugates (100–800 μg/mL) for 4–96 h postfertilization (hpf). Monitoring of mortality, hatching rate, and whole-embryo cellular death showed that incubation of low concentrations of the NPs did not exhibit adverse developmental toxicity during embryonic and larval stages of zebrafish. Minimal toxic effects were observed at high concentration (800 μg/mL) of CR@Fe3O4, causing mortality and delay in hatching cycles. However, CR@Fe3O4 exhibited higher toxic effect on zebrafish larvae, suggesting higher bioavailability of the NPs on the tested animal stage. This study provides an investigation on developmental toxicity in zebrafish caused by Fe3O4 NPs and provides innovative insight into CR@Fe3O4 NPs serving as an optical probe to study the potential nanotoxicological effects of NPs in in vivo systems.