Graphene not irritant to skin, study shows
A new study shows that graphene itself, unless produced with the use of irritant chemicals, is not irritant to the skin. The finding is of crucial importance to the development and use of artificial and electronic skin, wound healing dressings and skin sensors based on graphene.
Although worries of potential toxicity of graphene-based materials (GMBs) persist, most studies so far have focused on exposure by inhalation. Since a growing number of applications is based on solid forms of graphene that are in contact with the body, it is of prime importance to analyze the contact toxicity of these materials. A study by researchers in Spain and Italy, recently published in the journal Nanoscale, showed that in most cases graphene is not irritant to the skin.
Figure: Histological analysis, showing no irritation due to graphene (Fusco et al, Nanoscale 2020, 12, 610, CC BY 3.0 license)
The researchers used the formally adopted SkinEthic Reconstructed Human Epidermis (RhE) model to assess toxicity of single- and few-layer graphene produced with various methods, including CVD growth, ball-milling, ultrasonic exfoliation in surfactants, graphene oxide and reduced graphene oxide. The obtained RhE viabilities, a measure of toxicity, were excellent, with values significantly lower than the OECD threshold of 50%, for all types of graphene except that exfoliated in the presence of commonly used surfactants SDS and SDBS. The researchers repeated the same ultrasonic exfoliation method with non-irritant surfactants, such as melamine, which proved that graphene can be made non-toxic even with ultrasonic exfoliation.
These results provide a step forward to define GBMs’ occupational safety as well as their safe use in devices directly applied to the skin, suggesting that the use of non-toxic surfactants as exfoliation agents may improve their safety.