Lanthanide ion-doped carbon dots (Ln-CDs) as fluorescent nanoprobes: a review

Breakthroughs in nanoscale science and engineering have facilitated the design of nanomaterials with exceptional optical behaviors. Over the past decade, numerous fluorescent nanoprobes have been reported for the highly sensitive and selective detection of a wide range of analytes. Among these, doped carbon dots (CDs) have become a major focus of researchers across multiple disciplines due to their exceptional physicochemical and optical properties. Lanthanide ion-doped carbon dots (Ln-CDs) have attracted increasing attention in recent years as specialized nanoprobes for luminescent detection because of their unique optical behavior, chemical stability, and low toxicity. However, most existing studies are limited to luminescence color modulation under different excitation wavelengths, and only a few reports have exploited dual-emission sources for nanoprobe construction. This review summarizes lanthanide-ion-doped carbon dots, highlighting the unique roles of lanthanide ions, doping mechanisms, and their advantages for analytical applications. In addition, the applications of these nanoprobes in various fields, including metal-ion detection, pharmaceutical analysis, contaminant monitoring, anthrax biomarker detection, and biomolecule sensing, are systematically discussed. In summary, Ln-CD-based nanoprobes show potential as promising candidates for future analytical platforms for the detection of multiple analytes.