Raspberry-derived carbon dots for specific detection of intracellular copper ions†

The detection of intracellular copper ions is crucial for advancing biomedical research and enhancing disease diagnosis. In this study, blue emissive carbon dots (B-CDs) were successfully synthesized using raspberry as the carbon source through a simple hydrothermal method. Characterization techniques combined with theoretical calculations confirmed that the fundamental structural unit of B-CDs is a twelve-membered aromatic ring rich in oxygen and nitrogen functional groups. The B-CDs exhibited high selectivity for Cu²⁺, showing a strong linear response in the concentration range of 0 to 150 μM, with a detection limit of 0.39 μM. Zeta potential and hydrodynamic size measurements indicated that the B-CDs interact with Cu²⁺via electrostatic forces. Further studies revealed that the fluorescence quenching of B-CDs in the presence of Cu²⁺ is primarily due to a dynamic quenching process. Moreover, B-CDs were successfully applied to detect intracellular Cu²⁺. These findings not only show significant potential of B-CDs in fluorescence sensing but also provide valuable insights for the design of efficient carbon-based sensors.