Recent progress on electroanalytical sensing of small molecules and biomolecules using carbon dots: A review

The carbon dot (CD) family has gained significant attention due to their tunable photoluminescence, physicochemical properties, low toxicity, high stability, chemical inertness, water solubility, and biocompatibility. These exceptional properties have increased their utilization in electroanalytical sensing applications for various small molecules and biomolecules. Electroanalytical sensing methods are simple techniques that detect or identify target analytes quantitatively or qualitatively by analyzing electrochemical signals such as current or potential in an electrochemical cell. These methods offer several advantages, including operational simplicity, cost-effectiveness, high accuracy, low detection limit, less analysis time, and reproducibility. This review presents a comprehensive summary of recent advancements in the electroanalytical applications of CDs, with a particular focus on their role as sensors for small molecules and biomolecules. CDs are categorized into five subclasses based on their composition, functionality, and applicability. These include CDs with or without heteroatom doping, composite CDs, CDs complexed with metals, CDs doped or supported with metal nanoparticles, and polymer-supported CDs. The review elucidates the underlying principles of electrochemical signal generation and detection mechanisms associated with these molecules. Furthermore, it provides insight into the synthetic pathways to prepare these CDs.