Water-soluble pillar[5]arene modified amphiphilic graphene quantum dots with excellent penetration for intracellular imaging

Abstract Amphiphilic graphene quantum dots (A-GQDs) reveal prodigious potential application in bioimaging, resulting from their hydrophilic and lipophilic properties, as well as their good biocompatibility and negligible cytotoxicity. Herein, green fluorescent A-GQDs with single-layer graphene structure were prepared by one step of hydrothermal method. The A-GQDs with the average size of 3.5 nm displayed excitation-independent emission due to uniform size. A-GQDs emitted bright fluorescence on the surface of the cell membrane of MCF-7 cells when they were co-cultured with MCF-7 cells, which was similar to that of QSG-7701 cells. The water-soluble pillar[5]arene (WP5) was then incorporated on to the A-GQDs via π-π interaction and electrostatic interaction. There was different labeling imaging effect of MCF-7 and QSG-7701 cells achieved by combining the merits of WP5 and A-GQDs compared with individual A-GQDs. The synthesized composites not only had a certain enhancement in fluorescence, but also constructed a penetrating channel through the cell membrane, so that the entire cell had a distinct imaging. Therefore, these composites might be a potential candidate for applications in visualization of cell membrane and bioimaging.