Doped Carbon Dots as Promising Fluorescent Nanosensors: Synthesis, Characterization, and Recent Applications

Carbon dots (CDs) have recently attracted attention as a new class of photoluminescent materials with promising optical, chemical, and electrical properties. They have been proposed for various applications, such as pharmaceutical sensing, biomarker detection, and cellular bioimaging, by virtue of their economical synthesis, cheap starting materials, water-solubility, excellent chemical stability, good biocompatibility, and low toxicity. Hetero-atom doping is a reliable and adaptable strategy for enhancing the photoluminescence, electrical, and structural characteristics of CDs. Herein, we present an update on heteroatom-doped CDs. Various modern synthetic routes are highlighted, ranging from synthetic processes to doping components. In addition, the optical and biological properties and the possible applications of heteroatom-doped CDs are discussed. This review will provide an overview of recent advances in doped CDs and their expected future perspectives.