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

Abstract

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 sp2 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.

Multifunctional scaffolds for biomedical applications: Crafting versatile solutions with polycaprolactone enriched by graphene oxide

“…[49][50][51][52] The aforementioned signals of the CH 2 groups of PCL, which were also observed in the FT-IR spectra [Figs. 26,47,53 The mechanical characterization of scaffolds is reported in Fig. 2.…”

“…Reduced graphene oxide (rGO), on the other hand, stands as a deoxygenated iteration of GO. 25,26 While the reduction processes do not fully recover the pristine graphene structure, the removal of oxygen groups results in an increased C/O ratio, a tunable restoration of the sp 2 structure, improved mechanical strength, expanded surface area, enhanced stability, hydrophobic characteristics, and an increase in electrical conductivity. 27,28 Graphene, GO, and rGO possess distinctive bioactive properties due to their surface groups and consequently to their capacity of dissolving in apolar and polar solvents, respectively.…”

The osteoconductive properties of graphene-based material surfaces are finely tuned by the conditioning layer and surface chemistry

“…PCL–GO coatings were prepared using GO samples with tailored surface chemistry and compared with uncoated PCL scaffolds used as controls. Precisely, coatings were made with GO, a GO enriched with additional carboxyl groups (GO–COOH) and a reduced graphene oxide (rGO) depleted in oxygen-based functional groups after the treatment with the mild and green reducing agent sodium ascorbate 44,45 (Fig. S1A, ESI†).…”

“…Reduced GO (rGO) was synthesized from GO by follwing a reported procedure. 45 Briefly, 10 mL of an aqueous dispersion of GO 4.25 mg mL −1 was diluted to 50 mL of volume using Milli-Q water. Then, 425 mg of sodium ascorbate (2.14 mmol) was added to the dispersion and the mixture was stirred at room temperature for 72 h. Subsequently, the mixture was centrifuged at 4000 rpm for 30 min in water (four times) discharging away the supernatant and keeping the solid black precipitate.…”

“…In this paper, we exploited recently developed GO synthesis methods 44,45 to enable the chemical manipulation of GO coatings for 3D-printed PCL scaffolds. Specifically, GO, carboxylated GO (GO–COOH), and reduced GO (rGO) coatings were produced and the effects of the different GO surfaces on cell behaviour were evaluated in simulated in vivo conditions.…”