Comparison of Carbon Dots Prepared in Deep Eutectic Solvent and Water/Deep Eutectic Solvent: Study of Fluorescent Detection of Fe3+ and Cetirizine and their Photocatalytic Antibacterial Activity

In this study, two solvents (deep eutectic and water/deep eutectic solvents) were used for N-doped carbon dots (N-CDs) preparation by microwave irradiation. The solvent can influence surface chemical composition, quantum yield, morphology, and fluorescence of CDs. N-CDs synthesized in water/deep eutectic solvent (DES) had better quantum yield (24.5%) with respect to N-CDs synthesized in deep eutectic solvent (17.4%). These carbon dots were used as a rapid and high sensitive “off–on” fluorescent probe for the determination of Fe³⁺ ion and cetirizine. Morphology and structure of the N-CDs were characterized by FT-IR, UV–Vis, XRD and TEM. Linear range and detection limit for N-CDs synthesis in deep eutectic solvent for cetirizine were 0.08–48 µM and 15 nM, respectively and for N-CDs synthesis in water/deep eutectic solvent were 0.03–50 µM and 10 nM, respectively. Applicability of this nanoprobe was tested in cetirizine determination in serum sample. Antibacterial activities of the two synthesized N-CDs were also investigated using agar disk diffusion method.