Is there Toxicity of Graphene in Human Sperm?


Do you want to attract media attention by studying the toxicity of a nanomaterial? Then use graphene and study human sperm.

Carbon Nanotubes with a Carboxyl Group and Reduced Graphene Oxide

There are already several studies that have taken this approach. The new study, published in Scientific Reports, shows that concentrations between 1 and 25 μg/ml do not affect sperm viability. The new work, which may be seeking an Ig Nobel Prize, uses sperm to study cytotoxicity because this is the easiest route in humans.

Previous studies in animal models (intravenous administration to mice at doses up to 1 mg/ml) show that oxidative stress damages DNA and cell membranes, accumulates in the testes, and causes inflammation, nodules and lesions, and decreased sperm motility.

The new work examines two functionalized carbon-based nanomaterials that have been proposed for biomedical applications. Specifically, carbon nanotubes with a carboxyl group (CNT-COOH) and reduced graphene oxide (rGO).

The article is Waseem Asghar, Hadi Shafiee, …, Utkan Demirci, “Toxicology Study of Single-walled Carbon Nanotubes and Reduced Graphene Oxide in Human Sperm,” Scientific Reports 6: 30270 (19 Aug 2016).

 

 

 

Carbon nanotubes and graphene are insoluble in water, so they are functionalized to improve their solubility and binding to certain drugs. Single-layer carbon nanotubes are usually functionalized with a carboxyl group (SWCNT-COOH). To functionalize single-layer graphene sheets, graphene oxide is used, which is partially reduced to improve electrical conductivity, resulting in the so-called RGO.

 

The viability of human spermatozoa in culture with different concentrations of SWCNT-COOH or RGO was quantified after 30 minutes and after 3 hours. No effects on sperm viability are observed at doses below 25 μg/ml.

However, evidence of possible oxidative stress is observed, which could have negative effects on male fertility at higher levels and for longer periods than those studied. For this reason, the authors of the study call for future analyses of the effects of these nanomaterials on sperm.