One-pot green synthesis of water-soluble carbon nanodots with multicolor photoluminescence from polyethylene glycol

Water-soluble fluorescent carbon nanodots (CNDs) were fabricated directly from polyethylene glycol (PEG) by a simple one-pot thermal treatment. In the formation of such CNDs, PEG played two essential roles: the carbon source and surface passivating agent. CNDs were used directly without any additional separation or purification procedure and yet have a comparable quantum yield with self-surface passivation CNDs or passivation-absent ones. The products were shown to be soluble in water and common organic solvents, and emitted bright multicolor fluorescence with excitation and pH dependent emission properties. The extensive characterization results likewise gave an insight into the formation and the luminescence mechanism of the CNDs. Cytotoxicity tests and cellular uptake experiments of the CNDs further demonstrated their viability in biochemical applications.