The unique economical design of sulfur and nitrogen co-doped carbon dots with high photoluminescence quantum yield and superior performance for environmental Hg²⁺detection.

Due to the excellent biocompatibility, carbon dots (CDs), which are attracting considerable attention as new quantum-sized carbon-containing fluorescent nanoparticles, are becoming both an important class of imaging probes and a versatile platform for biosensors. In the process of transferring carbon dots from proof-of-concept studies to real bioimaging and biosensing applications, major advances have already been made in their synthesis, structure, properties, mechanism of fluorescence, and evaluation of biocompatibility and bio-applications. This review aims to summarize the recent developments and trends in carbon dots. Investigations of preparation methods, fluorescent properties and applications as biosensors and in bioimaging for carbon dots are described. In addition, this review highlights on the design and construct of a carbon dot fluorescent ratiometric biosensing platform for the detection of enzymatic activity, substrate and inhibitor concentrations related to the production or consumption of H2O2. This review provides perspectives on future opportunities and the remaining challenges confronting this research field.

Cu-doped carbon dots were synthesized by a one-step hydrothermal method and used as a “turn-off” fluorescent probe in the detection of Fe³⁺ ions.