A novel thiol-ene click reaction for preparation of graphene quantum dots and their potential for fluorescence imaging

Graphene quantum dots (GQDs), as a kind of carbon dots with the structure of graphene, possess fascinating properties of both carbon dots and graphene have attracted increasing attention for various applications especially in the biomedical fields. It is therefore, many methods for preparation of GQDs have been developed over the last decade. However, most of the previous reports are required tedious experimental procedure and hazardous agents. In this study, we developed an unparalleled preparation method for preparation of GQDs from graphene oxide through a one-step thiol-ene click reaction. More importantly, many carboxyl groups have been introduced on the surface of GQDs during this procedure. The characterization results demonstrated that these GQDs display small size, uniform morphology, high water dispersibility and strong green fluorescence. Biological assays suggested that these GQDs are of low cytotoxicity and efficient cell uptake performance. More importantly, many other GQDs could also been fabricated through the thiol-ene click reaction owing to the universality of thiol-ene click reaction. Therefore, this novel strategy based on thiol-ene click reaction should be of great importance for advancing the preparation and biomedical applications of GQDs.