Synthesis of superior dispersions of reduced graphene oxide

Highly dispersible and biocompatible reduced graphene oxide (rGO) is greatly appealing for its biological applications. Natural L-lysine was employed as a reducing agent and sodium cholate as a stabilizer to synthesize stable suspension of rGO in this work. The effective reduction of graphene oxide by L-lysine was confirmed using X-ray diffraction, transmission electron microscopy, UV-vis, FT-IR, XPS and Raman spectroscopy. More importantly, the dispersibility of the as-made rGO was remarkably enhanced by tip sonication. As a result, the dispersible concentration of rGO was up to 4 mg mL(-1) in water, which is the highest dispersibility so far. In addition, both L-lysine and sodium cholate are biocompatible. Hence this work provided a facile approach to large-scale preparation of biocompatible rGO.