Graphene and Flavin Mononucleotide Interaction in Aqueous Graphene Dispersions

A fundamental understanding of the interaction between graphene and a stabilizer is needed for the development of stable aqueous graphene dispersions. Here, we studied the interaction of graphene with the flavin mononucleotide (FMN) in water. The UV-vis absorption spectra revealed blue shifts of the FMN absorption bands II (374 nm) and I (445 nm) in the presence of graphene. Furthermore, Fourier transform infrared analysis showed that the graphene also upshifted the FMN vibration modes C-10a=N-1 and C-4a=N-5, which correspond to the FMN isoalloxazine binding sites N(1) and N(5), respectively. In addition, thermogravimetric analysis showed that the thermal stability of graphene was enhanced by the adsorbed FMN, which supports the strong interaction. These results confirm that FMN adsorbs on the graphene surface in parallel conformation and hinders hydrogen bonding at the FMN isoalloxazine binding sites.