Fluorescence mechanism and biomedical applications of graphene quantum dots

Abstract

Graphene quantum dots (GQDs) are fluorescent graphene nanoparticle that have tunable emission wavelength, high emission intensity and biocompatibility. The fluorescence mechanism is still indecisive, yet explanations exist. Surface or edge defects and quantum confinement are two major explanations and they accounted for the florescence properties observed so far. GQDs quantum confinement is applied to change the emission wavelength. Surface functional groups usually improve biocompatibility and solubility. Under several cases, surface defects are also engineered to tune emission wavelength and intensity to serve specific engineering propose. GQDs have found applications in bioimaging, biosensing, and therapy. GQDs can generate high intensity emission in the NIR-II window which is ideal in in vivo bioimaging. GQDs can be generated from folic acid in a one-step procedure. The GQDs generated this way can track folate receptor and help cancer diagnostics. High intensity emission also enables GQDs to be used in photothermal or photodynamic therapy. Future applications will be promoted by a better understanding of GQDs fluorescence mechanisms.