Intraparticle FRET of Mn(ii)-doped carbon dots and its application in discrimination of volatile organic compounds.

To achieve an energy transfer system in emissive nanoparticles, a conventional strategy is to graft an exterior fluorophore onto the surface of the host. In this paper, we report for the first time an intraparticle Förster resonance energy transfer (IPFRET) system formed intrinsically in Mn(ii)-doped carbon dots (MCDs). In virtue of the small particle size of MCDs and the modified band structure, intraparticle energy transfer from a fluorophore-like donor component to a metal-related acceptor component takes place. The IPFRET of MCDs was found to be sensitive to the chemical environment (e.g., polarity) via the effects of external influences on the metal-to-ligand charge transfer (MLCT). Surface enhanced Raman spectroscopy was employed to verify the MLCT-related metal-coordination conformation, and proved capable of collecting bonding information of metal-doped species of carbon dots. Benefitting from the sensitivity of the IPFRET signal, MCDs exhibited high potential in sensing applications.