Fluorescent Carbon Dots and their Applications in Sensing of Small Organic Molecules

Background: Fluorescence-based sensing is considered highly sensitive and fluorescent probes with improved properties are always preferred. Fluorescent carbon dots (CDs) are newly emerging quasi-spherical nanoparticles of less than 10 nm in size and belong to the carbon nanomaterial’s family. CDs have great potential as fluorescent probes and currently are under open discussion by the researchers due to their striking properties such as low environmental hazard, high selectivity, greater sensitivity, good biocompatibility, tunable fluorescent properties and excitation dependent multicolor emission behavior. Introduction: This review demonstrates various available methods for fabrication of fluorescent CDs, capping of CDs and characterization with various techniques, including UV-visible, FT-IR, and TEM. Analytical applications using CDs for the sensing of small organic molecules, specifically nitroaromatic compounds in the environmental samples, are complied. Methods: The review covers literature related to synthesis and characterization of carbon dots. It includes around 171 research articles in this field. Results: Carbon dots can be synthesized using numerous routes. In all cases, CDs possess spectral properties with little variation in wavelength maxima. The optical properties of CDs can be tuned by compositing these with metallic quantum dots or by modifying their surface with desired functionalities. HR-TEM is needed to see the morphology and size of particles, whereas UV-Visible and FTIR are indispensable tools for this kind of research. These particles are successfully applied to sense small molecules in some matrices. Conclusion: Carbon dots are bright stars in fluorescent sensing of small molecules. However, more research is needed to determine small organic molecules in diversified areas of analysis.