Green synthesis of multifunctional carbon dots from Crataegi Fructus for pH sensing, cell imaging and hemostatic effects

Multifunctional carbon dots with intrinsic biological activity and fluorescent properties exhibit tremendous potential for applications in various fields, especially in the biomedical field. This paper reports a green and facile method for the synthesis of multifunctional carbon dots (CFCDs) via pyrolysis using the herbal medicine Crataegi Fructus as a precursor, and the fluorescent properties and biological activities of CFCDs are investigated, while the corresponding mechanisms are explored. The obtained CFCDs present a graphitic structure with an average particle size of 2.35 nm, abundant functional groups on their surface, and possess high aqueous solubility and excellent stability. Furthermore, under acidic conditions, these CFCDs have pH-dependent fluorescence properties based on protonation and deprotonation, showing a high linear correlation with pH values ranging from 0.5 to 4.5. The low cytotoxicity of CFCDs and their efficient internalization by cells make them ideal for cell imaging. More importantly, CFCDs exert good hemostatic effects through the extrinsic and common pathway and promote platelet aggregation. In conclusion, CFCDs can simultaneously realize pH sensing, cell imaging, and hemorrhagic disease treatment and, thus, have potential for wide application in medical domain.