Synthesis of high quality and biocompatible graphene quantum dots by thermal decomposition of silicon carbide

Abstract

Graphene quantum dots (GQDs) are expected to be used in bio-fields due to unique optical properties and low toxicity. However, the conventional synthesis methods have disadvantage such as poor quality of GQD and complicated production process. Therefore, by applying the silicon carbide (SiC), a well-known material in synthesis of epitaxial graphene, GQD was fabricated by heating SiC in a medium vacuum. GQD solution was prepared by detached GQDs from SiC. As prepared GQD was composed of high quality graphene and had a uniform size and thickness. The PL signal of pristine GQD-ethanol solution without any treatment was too weak for using bio-imaging field. However, when additional sonication process for 30minutes was performed to as prepared GQD solution, the intensity of PL was dramatically increased. The surface of the GQD was found to be oxidized after an additional sonication process applied to the GQD through XPS analysis. It was presumed that the surface passivation was the origin of photoluminescence of GQD solution. GQD showed low cytotoxicity and it was observed that cells were maintained in a normal state even after GQD was injected into the cells in the cytotoxicity tests. Thus, it is expected that GQD fabricated by annealed SiC will be used in bio-field at future.