Cadmium induced aggregation of orange–red emissive carbon dots with enhanced fluorescence for intracellular imaging

Cadmium is a notorious toxic heavy metal, that poses serious threat to human health. Sensitive and selective detection of cadmium in cells is of great significance in poison screening and disease diagnosis. Orange–red emissive carbon dots (OR-CDs), prepared from the calcination of selected carbon sources 5-amino-1, 10-phenanthroline (Aphen) and salicylic acid (SA), were found to act as a “turn on” type fluorescence probe for Cd2+ detection. The structure and optical properties of OR-CDs were comprehensively investigated by both experimental characterizations and density functional theory (DFT) calculations. The OR-CDs consist of a basic unit of nine aromatic rings, and the N/O binding sites on the OR-CDs can specifically bind with Cd2+, leading to aggregation induced enhanced emission (AIEE). A detection limit of 0.30 μM was achieved for Cd2+ with a linear range of 0.80–100 μM. OR-CDs can not only be used for intracellular Cd2+ imaging but also have the potential to alleviate cadmium poison in living organisms. [Display omitted] •Orange-red emissive carbon dots (CDs) was synthesized by a simple calcination method.•The CDs showed a sensitive and selective turn-on fluorescence response to Cd2+.•The specific fluorescence increment was ascribed to Cd2+ induced aggregation of CDs.•DFT calculation elucidated the perfect match between Cd2+ and rigid structure of CDs.•The CDs was successfully applied for intracellular Cd2+ sensing and imaging.