Facile synthesis of fluorescent carbon dots from Prunus cerasifera fruits for fluorescent ink, Fe(3+) ion detection and cell imaging.

Carbon dots (CDs) synthesized from natural products have drawn numerous attentions due to some unique properties. Here, Prunus cerasifera fruits were used as carbon source to synthesize high luminescent CDs by hydrothermal method. The obtained CDs were characterized by TEM, FTIR and XPS methods, founding the CDs were near-spherical and contained abundant nitrogen element. The CDs aqueous solution exhibited bright blue fluorescence under ultraviolet illumination, with the maximum emission at 450 nm. They could be potentially used as invisible fluorescent ink by written on the paper and irradiated by UV light, due to their fluorescent properties. Moreover, the CDs were found being selectively quenched by Fe3+ ion. The quench of CDs was linearly related to the concentration of Fe3+ ion in the range of 0-0.5 mM, meaning they could be developed as fluorescent probe of Fe3+ ion. At last, the CDs were used for cell imaging, founding they were low toxicity to HepG2 cells and exhibited blue and green fluorescence under a fluorescence microscope. In summary, the CDs prepared from Prunus cerasifera fruits exhibited excellent fluorescence properties, and could be potentially applied in the field of fluorescent ink, Fe3+ ion detection and cell imaging.

Ma H ，Sun C ，Xue G ，Wu G ，Zhang X ，Han X ，Qi X ，Lv X ，Sun H ，Zhang J ... -  《-》

On-off-on fluorescent carbon dots from waste tea: Their properties, antioxidant and selective detection of CrO(4)(2-), Fe(3+), ascorbic acid and L-cysteine in real samples.

In this work, we reported an economical plant-based hydrothermal method for one-pot green synthesis of water-soluble carbon dots (Tea-CDs) by using waste tea extract as a carbon source. The synthesized Tea-CDs were characterized by UV-visible, fluorescence, FT-IR, TEM, XPS and XRD. The Tea-CDs were found to remove hydroxyl and superoxide anion radical in vitro. In addition, the Tea-CDs exhibited bright blue fluorescence under UV-light (λex = 365 nm), and the fluorescence could be effectively quenched by CrO42- and Fe3+ ions. Meanwhile, the fluorescence of Tea-CDs-CrO42- and Tea-CDs-Fe3+ systems could be again easily recovered by ascorbic acid (AA) and L-cysteine (L-Cys). As an on-off-on fluorescent nano-sensor of the Tea-CDs, the sensitive detection of CrO42-, Fe3+, AA and L-Cys were all performed, showing that the good linear relationships between fluorescence intensity of Tea-CDs and concentration of all testing samples. Finally, the sensors successfully detected CrO42-, Fe3+, AA and L-Cys in commercially available real samples with satisfactory recovery ranges. The prepared sensors offer distinct advantages including low cost, simple handling, good sensitivity and high selectivity.

Chen K ，Qing W ，Hu W ，Lu M ，Wang Y ，Liu X ... -  《-》

Green synthesis of carbon dots originated from Lycii Fructus for effective fluorescent sensing of ferric ion and multicolor cell imaging.

Green, economical and effective method was developed for synthesis of fluorescent carbon dots (CDs), using one-pot hydrothermal treatment of Lycii Fructus. Optical and structural properties of the CDs have been extensively studied by UV-visible and fluorescence spectroscopic, x-ray diffraction (XRD) techniques, transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Surface functionality and composition of CDs has been illustrated by Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) spectra and elemental analysis. The fabricated CDs possess stable fluorescent properties. The fluorescent quantum yield of the CDs can reach 17.2%. The prepared CDs emitted a broad fluorescence between 415 and 545nm and their fluorescence was tuned by changing excitation wavelength. Meanwhile, the fluorescence intensity of the CDs could be significantly quenched by Fe3+ (turn-off). The CDs exhibit captivating sensitivity and selectivity toward Fe3+ with a linear range from 0 to 30μM and a detection limit of 21nM. The prepared CDs were successfully applied to the determination of Fe3+ in the urine samples, the water samples from the from the Yellow River and living HeLa (Henrietta Lacks) cells. Moreover, the low-toxicity and excellent biocompatibility of the CDs were evaluated through MTT assay on HeLa cells. The CDs were also employed as fluorescent probes for multicolor imaging of HeLa cells successfully.

Sun X ，He J ，Yang S ，Zheng M ，Wang Y ，Ma S ，Zheng H ... -  《-》

Green Synthesis of Self-Passivated Fluorescent Carbon Dots Derived from Rice Bran for Degradation of Methylene Blue and Fluorescent Ink Applications.

Jothi VK ，Ganesan K ，Natarajan A ，Rajaram A ... -  《-》

Nitrogen-doped carbon dots originating from unripe peach for fluorescent bioimaging and electrocatalytic oxygen reduction reaction.

This paper reports the robust hydrothermal synthesis of nitrogen doped carbon dots (N-CDs) using the unripe fruit of Prunus persica (peach) as the carbon precursor and aqueous ammonia as the nitrogen source. The optical properties of synthesized N-CDs were characterized by ultraviolet visible (UV-Vis) and fluorescence spectroscopy techniques. The synthesized N-CDs were emitted blue light when excitated with a portable UV lamp. The materials with the optical properties were characterized further by high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), Raman, Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The mean size of the N-CDs was approximately 8nm, as calculated from the HRTEM image. The d-spacing of N-CDs, calculated using Bragg law, was approximately 0.21nm, which was consistent with the interlayer distance calculated from the HRTEM image. FT-IR spectroscopy and XPS revealed the presence of the phytoconstituents functionalities of peach fruit over the N-CDs surface and a high level of nitrogen doping on carbon dots (CDs) was confirmed by XPS studies. These results suggest that the unripe fruit extract of peach is an ideal candidate for the preparation of N-CDs. The resulting N-CDs showed excellent optical properties in water. The synthesized N-CDs exhibited a high fluorescence quantum yield and low cytotoxicity, and can be used as fluorescence imaging probes. In addition, the N-CDs were catalytically activite towards the oxygen reduction reaction (ORR). The N-CDs exhibited good catalytic activity in an alkaline medium (0.1M KOH) with a remarkable ORR of approximately 0.72V vs reversible hydrogen electrode (RHE), and O2 reduction follows mainly a 2 electron pathway by being reduced to hydrogen peroxide. The 2-electron reduction pathway is used in industry for H2O2 production.

Atchudan R ，Edison TNJI ，Lee YR 《-》