Biocompatibility and hemocompatibility of hydrothermally derived reduced graphene oxide using soluble starch as a reducing agent.

Graphene-based nanomaterials (GBNs) have many applications as biomedical materials in tissue engineering and regenerative medicine. We report on the preparation of starch-(functionalized) reduced graphene oxide nanosheets (SRGO) using soluble starch as a reducing agent in a hydrothermal method, and their in vitro interactions with human skin fibroblasts and red blood cells (RBCs). Our results indicate that soluble SRGO nanosheets were prepared using graphene oxide (GO) as a raw material. SRGO-1 and -10, which were prepared using different concentrations of soluble starch after hydrothermal treatment, were characterized by ultraviolet-visible spectroscopy and showed a peak shift at 260 nm corresponding to the deoxygenation of GO and restoration of the conjugated aromatic structure. Dynamic light scattering and zeta potential measurements were used to determine Z-average sizes and surface charges of GO and SRGOs. X-ray diffractometry, attenuated total reflectance Fourier-transform infrared spectroscopy, and Raman spectroscopy revealed the progressive elimination of labile oxygen functional groups during hydrothermal treatment and restoration of the π-conjugated network. X-ray photoelectron spectroscopy showed de-oxidation of SRGOs, which had high carbon to oxygen ratios (C/O) as compared with GO. Interactions of SRGO-1 and -10 with skin fibroblasts showed excellent biocompatibility even at a concentration of 200 μg/ml with cell viabilities up to 88% and 90%, respectively, whereas notable cytotoxicity was observed for GO at 20 μg/ml. Similarly, SRGO-1 and -10 did not exhibit toxicity to RBCs compared to GO. Biofilm formation and metabolic activities of biofilm by the bacterium Staphylococcus aureus were also evaluated using a crystal violet and a tetrazolium reduction assay, respectively. The described hydrothermal method used to synthesize SRGO provides a cheap, facile, and environmentally friendly means of producing water-dispersible, biocompatible and hemocompatible reduced GOs for the fabrication of novel GBNs for various biomedical applications.