Bio-conjugation of graphene quantum dots for targeting imaging

Graphene quantum dots (GQDs) with strong photoluminescence (PL) and chemical modification have attracted tremendous interest for fundamental and applied research owing to their special low-cost production and low toxicity. However, most of the research focused on the GQDs without much targeted design, which limited their applications in specific bio-based fields. Inspired by this fascinating conundrum, we demonstrate GQD-based bio-conjugation. Relying on sedimentation coefficient differences for the density gradient ultracentrifuge (DGU) separation of conjugates with different proteins, ultra-purified conjugates were obtained. We demonstrate the first targeted imaging in both cells and tissue models with single or multi color staining, which shows universality for different kinds of biomolecules.