Carbon quantum dots from natural sources as sustainable probes for metal ion sensing: Preparation, characterizations and applications

Carbon Quantum Dots from Natural Sources (NACQDs) is a novel type of carbon-based material that have garnered significant attention due to their remarkable features, including luminescence, photostability, nanoscale size, water solubility, low toxicity, biocompatibility, and cost-effectiveness. The synthesis of NACQDs involves a diverse range of natural sources, such as fruits, foods, beverages, human and animal derivatives, vegetables, leaves, and waste materials. Various synthesis methods, including electrochemical approach, chemical oxidation, hydrothermal carbonization, ultrasonic techniques, microwave-assisted synthesis, solvothermal method, laser ablation technique, thermolysis, and atmospheric plasma-based synthesis, have been explored to tailor the size and properties of NACQDs. Characterization techniques like Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TЕM), ultraviolet absorption, fluorescence properties, and nuclear magnetic resonance (NMR) have provided invaluable insights into the physical and chemical characteristics of NACQDs. This review highlights the immense potential of NACQDs in metal ion sensing applications and underscores the need for further investigation to enhance their reproducibility and precise control over their properties. NACQDs hold great promise as versatile nanomaterials for metal ion sensing and are poised to revolutionize diverse fields, ranging from environmental monitoring to biomedical diagnostics and chemical analysis.