Unlocking the Stability of Reduced Graphene Oxide Nanosheets in Biological Media via Use of Sodium Ascorbate

Graphene oxide and reduced graphene oxide (RGO) are carbon bidimensional nanomaterials largely exploited in biomedicine. Their unique interactions with eukaryotic and prokaryotic cells are used to obtain precise intracellular delivery, to create device coatings, and to design theranostic materials for both therapeutic and imaging applications, mainly in the cancer research field. It is known, however, that the hydrophobic behavior of RGO limits its stability in biological media. Here, the employment of sodium ascorbate (NaA) as a reducing agent for the preparation of RGO to provide a nanomaterial with remarkable suitability for applications in cell culture media is proposed. It is demonstrated via a combined experimental and theoretical approach that NaA is able to yield a peculiar RGO derivative, exerting a twofold effect, that is, C sp(2) network restoration upon epoxide reduction and RGO edge functionalization via H-bonding, lending RGO a so far unexampled dispersibility in aqueous-based media. The kinetic stability of the bidimensional layers of RGO obtained from NaA is demonstrated together with its superior biocompatibility for drug delivery, unlocking outstanding potentialities for biological applications.