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Hydrothermal conversion of Magnolia liliiflora into nitrogen-doped carbon dots as an effective turn-off fluorescence sensing, multi-colour cell imaging and fluorescent ink B Biointerfaces

Atchudan, Raji, Edison, Thomas Nesakumar Jebakumar Immanuel, Aseer, Kanikkai Raja, Perumal, Suguna, Lee, Yong Rok
Colloids and surfaces 2018 v.169 pp. 321-328
Magnolia liliiflora, carbon quantum dots, cytoplasm, detection limit, dispersibility, flowers, fluorescence, hepatocytes, hot water treatment, image analysis, industrial effluents, ions, iron, moieties, nitrogen, rats, zeta potential
The present work illustrates the potential uses of nitrogen-doped multi-fluorescent carbon dots (N-CDs) for Fe³⁺ sensing, cellular multi-colour imaging, and fluorescent ink. N-CDs were synthesized using Magnolia liliiflora flower by the simple hydrothermal method. The resulted N-CDs was found to be nearly spherical in shape with the size of about 4 ± 1 nm and showed competitive quantum yield around 11%. The synthesized N-CDs with uniform size distribution and high content of nitrogen and oxygen-bearing functional groups exhibit excellent dispersibility in aqueous media. The N-CDs were able to detect a high concentration of Fe³⁺ ions (1–1000 μM) with a limit of detection is about 1.2 μM by forming N-CDs-Fe³⁺ complex due to the functional groups such as nitrogen, carbonyl and carboxyl on the surface of N-CDs. Thus they could be used to remove pollutants from industrial wastewater. The electronic charge on the surface of the N-CDs and N-CDs-Fe³⁺ complex (zeta potential) is around −36 and 18 mV, respectively. In addition, these N-CDs show excitation-dependent fluorescence that was utilized for multi-colour in vitro cellular imaging in rat liver cells (Clone 9 hepatocytes). The N-CDs are rapidly uptake in the cell cytoplasm and showed high cytocompatibility on cellular morphology. Moreover, as the N-CDs possess strong fluorescence and anti-coagulation they could be utilized in fluorescent ink pens.