Exploring the toxicity of a bismuth-asparagine coordination polymer on the early development of zebrafish embryos

Nanoparticles are widely used in nanomedicine, raising concerns about their toxicity. In this study, the toxicity of bismuth-asparagine coordination polymer spheres (BACP-2) was assessed in zebrafish embryos. Injection of 1-4 cell stage embryos with BACP-2 resulted in smaller head size (particularly smaller eye size), shorter body length, and pericardial edemas. The severity and occurrence of the resulting phenotype were concentration-dependent. The expression of genes such as krox20, orthodenticle homeobox 2 (otx2), and cardiac myosin light chain-2 (cmlc2) indicates that the effects of BACP-2 on the head and heart were related to changes in gene expression patterns. A delay in epiboly was observed, and the expression levels of the no tail (ntl) gene indicated that the delay in epiboly resulted both from the effect of BACP-2 on cell migration during epiboly and from slow growth. These findings indicate that BACP-2 exhibits concentration-dependent developmental toxicity, providing insight into the nanotoxicity of bismuth derivatives, which must be rigorously evaluated with respect to toxicity before their application in nanomedicine.