Photoluminescent carbon dots directly derived from polyethylene glycol and their application for cellular imaging

Photoluminescent carbon dots (C-dots) were prepared directly by a simple hydrothermal treatment using polyethylene glycol with different molar weight (400–6000 g mol−1) as the sole carbon source. The synthesized C-dots with tunable diameters of 2–4 nm exhibit excitation-dependent photoluminescent behavior. In contrast to previous methods, neither strong acid treatment nor further surface modification is necessary for this one-step process. The C-dots with well-defined surface chemistry and properties were well-dispersed in aqueous media and showed high photostability indicating they are suitable for use in different pH and NaCl aqueous solutions. The C-dots possessed low cytotoxicity, good photostability and can enter the cancer cells, making them suitable candidates for two-photon cellular imaging and labelling.