Graphene oxide (GO) is the most prominent host of magnetic nanoparticle (MNP) composites because its properties make it advantageous for large-scale production. … Graphene-based composites are then obtained by transformation of GO to reduced graphene oxide (RGO).
It's being used in other vaccines. See article: https://www.graphene-info.com/graphene-oxide-gives-boost-new-intranasal-flu-vaccine