Application of a Reduced Graphene Oxide Mask to Cells as an Effective Barrier to Cytotoxins

Toxic exposure damages tissues and cells. Deployment of a physical diffusion barrier on cell surfaces provides a simple method for inhibiting these cytotoxic effects. We have previously shown that thin (< 250 nm) films of thermally reduced graphene oxide (rGO) have low permeability to small molecules, and that these rGO films can be integrated with cells in a biocompatible manner using gelatin as a cell protectant. Here we use rGO films as diffusion masks to inhibit exposure of various mammalian cell types to a number of cytotoxins, in an effort to gauge the cytoprotective effect of the films. In separate trials, rGO-masked cells were exposed to 70% ethanol and 2.5% glutaraldehyde to determine the effectiveness of the rGO mask. We also evaluated the impact of mask thickness as well as the incorporation of other polymers with the mask on overall cytoprotective effectiveness. Applying LIVE/DEAD stain to cells exposed to 70% ethanol revealed clearly defined areas of live- and dead-stained cells corresponding to the areas with and without rGO coverage, respectively. LIVE/DEAD staining of glutaraldehyde-exposed cells indicated a significant amount of cell death occurring in cells underneath the mask. Further examination revealed isolated spots where the gelatin cell protectant was heavily crosslinked as a result of glutaraldehyde exposure. These results suggest that rGO masks can be strongly protective against certain cytotoxins such as ethanol, whereas others such as glutaraldehyde might penetrate the mask along defects.