Surrounding media sensitive photoluminescence of boron-doped graphene quantum dots for highly fluorescent dyed crystals, chemical sensing and bioimaging

We demonstrate that boron-doping of graphene quantum dots (B-GQDs) give rise to rich fluorescence owing to their peculiar interaction with the surrounding media. A B-GQDs borax (Na2B4O7·10H2O) solution was shown to be highly fluorescent in green, and upon evaporation, formed bright green fluorescent crystals. However, removing the borax left behind only blue and yellow luminescent solutions. These intriguing findings are rationalized by the insight that B-GQDs associate in the absence of borax whereas they form dative valence bonds with the bridgehead O atoms of borax in the presence of borax. We further demonstrate the use of the B-GQDs, for example, in chemosensor for detecting Al3+ and biomarker for cellular imaging.