Toxicity evaluation and translocation of carboxyl functionalized graphene in Caenorhabditis elegans

Abstract

Carboxyl functionalized graphene (G-COOH) can be potentially used for biosensing and medical applications. However, little is known about the in vivo behavior and toxicity of G-COOH. To investigate the in vivo translocation and toxicity of G-COOH and the underlying cellular mechanism, we employed Caenorhabditis elegans as a model for toxicological study. Prolonged exposure to 0.01–100 mg L⁻¹ of G-COOH from L1-larvae to adult day-1 did not cause any adverse effects on the lifespan, development, or functions of the intestine, neurons, and reproductive organs in exposed nematodes and their progeny. After prolonged exposure, G-COOH was not translocated into the secondary targeted organs such as reproductive organs and neurons or the body of the progeny of exposed nematodes. In the intestinal cells, G-COOH was mainly deposited in small-vesicle structures such as peroxisomes and lysosomes adjacent to microvilli and moderately deposited in the cytosol. Meanwhile, G-COOH exposed nematodes showed normal development and function of the intestine and normal biological function of the intestinal barrier. Moreover, G-COOH exposed nematodes had normal defection behavior and developmental state of AVL and DVB neurons that control the defecation behavior. Therefore, the G-COOH translocation pattern and functional state of the intestinal barrier and/or the defecation state may contribute greatly to the in vivo behavior and toxicity of G-COOH at concentrations less than 100 mg L⁻¹ in nematodes. Our results provide useful information on the in vivo properties of G-COOH and its future applications.