Impact of Carbon Nano-Onions on Hydra vulgaris as a Model Organism for Nanoecotoxicology

Abstract

The toxicological effects of pristine and chemically modified carbon nano-onions (CNOs) on the development of the freshwater polyp <i>Hydra vulgaris</i> were investigated in order to elucidate the ecotoxicological effects of CNOs. Chemical modifications of the CNOs were accomplished by surface functionalization with benzoic acid, pyridine and pyridinium moieties. thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy confirmed the covalent surface functionalization of CNOs. <i>Hydra</i> specimens were exposed to the carbon nanomaterials by prolonged incubation within their medium. Uptake was monitored by optical microscopy, and the toxicological effects of the CNOs on <i>Hydra</i> behavior, morphology, as well as the long-term effects on the development and reproductive capability were examined. The obtained data revealed the absence of adverse effects of CNOs (in the range 0.05-0.1 mg/L) <i>in vivo</i> at the whole animal level. Together with previously performed <i>in vitro</i> toxicological analyses, our findings indicate the biosafety of CNOs and the feasibility of employing them as materials for biomedical applications.