Good find. Also a good excuse. I'm not convinced changing the GO surface structure renders it harmless. Maybe in the short term under specific lab conditions. Surface treatments don't change the underlying molecular structure.

Graphene oxide (GO), widely employed for the delivery of biomolecules, excels in loading and delivering antigen and shows the potentiality of activating the immune system. However, GO aggregates in biological liquid and induces cell death, and it also exhibits poor biosolubility and biocompatibility. To address these limitations, various surface modification protocols have been employed to integrate aqueous compatible substances with GO to effectively improve its biocompatibility.