Pristine graphene quantum dots for detection of copper ions

To selectively detect Cu2+ ions is very important for controlling daily intake of Cu2+ ions and monitoring numerous biological processes. Fluorescence spectroscopic technique is a useful one for detection of copper ions. Previous methods always involve the use of metal Cd-based quantum dots (QDs), which suffer to the photobleaching and subsequent release of toxic metal ions. Herein, a simple method has been developed to detect Cu2+ ions by using pristine graphene QDs. Graphene QDs are synthesized by chemical oxidation of pitch graphite fibers. Our results indicate the photoluminescence (PL) of as-synthesized graphene QDs could be quenched by a group of metal ions while adding biothiol cysteine can only cause the significant recovery of the PL of graphene QDs quenched by Cu2+ ions. Our approach provides an easy and environmental friendly method for detection of Cu2+ ions and has the potential for future practical applications.