Some scientists are concerned that Graphene may be hazardous and toxic - for humans, animals and the natural environment. Researchers from Singapore's A*STAR have published a study on how graphite, graphite oxide, graphene oxide and reduced graphene oxide may effect bacteria (Escherichia coli in the study).
The researchers showed that the graphene-based materials kill substantially more bacteria than graphite-based materials. Graphene Oxide was the most dangerous material. The researchers say that most of the E.coli cells were individually wrapped by layers of graphene oxide. In contrast, E. coli cells were usually embedded in the larger reduced-graphene-oxide aggregates (see image above).
Cell-wrapping kill more cells than cell-trapping, and the researchers believe that this is because the direct contact of cell surface with graphene causes membrane stress and irreversible damage.