Acute ecotoxicity assessment of a covalent organic framework

Covalent organic frameworks (COFs) have recently attracted increasing interest for applications in the environmental field, and to this end, the evaluation of their potential toxicity is of importance prior to deploying these materials in the environment. Herein, we report for the first time the acute toxicity assessment of a COF using a zebrafish embryotoxicity test. We studied a TpBD-Me2 COF, a material that we recently showed to efficiently adsorb water pollutants. The COF induced moderate toxicity in the early developmental stages of zebrafish embryos at low concentrations (0.001 μg mL−1), which can be attributed mainly to its particulate size and shape rather than its chemical nature, as demonstrated in the scanning electron microscopy studies performed on the chorions of exposed eggs and by confocal fluorescence imaging of eggs that were exposed to a fluorescent-labeled TpBD-Me2. This study reinforces the relevance of performing acute toxicity tests in complex organisms to attend to the environmental risk of material exposure, and the necessity of developing supported formulations to prevent significant material release into the water.