Expansion Microscopy Revealed Specific Impacts of Nano Zinc Oxide on Early Organ Development in Fish

Abstract

Nanomaterials exhibit significant advantages in biomedical applications. However, their potential risks to organisms cannot be overlooked, particularly during early development. Traditional methods for assessing organ-specific toxicity are limited by their difficulty in exploring differences between materials at the nanoscale resolution. The novel expansion microscopy technique (ExM) provides an effective solution for high-resolution nanoscale imaging, allowing biological samples to be expanded approximately 4.5 times in three-dimensional space. ExM enables the visualization of proteins and nucleic acid targets in cells and tissues using conventional optical microscopy, achieving nanoscale imaging. The widespread application of nano zinc oxide (nZnO) in the biomedical field has raised concerns regarding toxicity. This study systematically assesses the toxicological changes and sources of nZnO and Zn²⁺ in the visual, skeletal muscle, and digestive systems. Our results indicated that appropriate concentrations of nZnO supported the normal early development in the visual and skeletal muscle systems, while potentially leading to excessive toxicity in the digestive system. Conversely, the concentrations of nZnO suitable for the development of the digestive system may be inadequate for the needs of the visual and skeletal muscle systems. This discrepancy may arise from differences in the solubility and bioaccessibility of nZnO in gastrointestinal fluids. Further RNA sequencing revealed differences in the sensitivity of various organs to nanomaterial exposure, highlighting the necessity of implementing comprehensive risk assessment strategies in toxicology. Overall, we visualized and quantified the subtle developmental toxicities of nZnO and Zn²⁺ across different organs for the first time. The application of expansion microscopy technique offered a novel perspective for evaluating the toxicity of nanomaterials.