scholarly journals Green Hydrothermal Synthesis of N-doped Carbon Dots from Biomass Highland Barley for the Detection of Hg2+

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3169 ◽  
Author(s):  
Xie ◽  
Cheng ◽  
Liu ◽  
Han
Keyword(s):  
Carbon Dots ◽  
Limit Of Detection ◽  
Amorphous Structure ◽  
Water Soluble ◽  
Diameter Distribution ◽  
High Quantum Yield ◽  
N Doping ◽  
Ft Ir ◽  
Doped Carbon Dots ◽  
Highland Barley

Totally water-soluble N-doped Carbon dots (N-CDs) were synthesized by a green hydrothermal method from biomass using Highland barley as a carbon source and ethanediamine as nitrogen source. TEM and XRD showed the graphitic amorphous structure and narrow diameter distribution of these N-CDs. N-doping to the crystal lattice and carrying many hydrophilic groups on the surface of N-CDs were verified by XPS and FT-IR. The as-synthesized N-CDs emitted strong blue fluorescence at 480 nm and owned a relatively high quantum yield of 14.4%. The product also could sensitively and selectively detect Hg2+ ions in the range of 10–160 μM and the limit of detection was equal to 0.48 μM.

scholarly journals N-Doped Carbon Dots Derived from Melamine and Triethanolamine for Selective Sensing of Fe3+ Ions

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Sathishkumar Munusamy ◽  
Sathish Sawminathan ◽  
Thanigaivelan Arumugham ◽  
Maura Casales Díaz ◽  
Srinivas Godavarthi ◽  
...  
Keyword(s):  
Water Samples ◽  
Carbon Dots ◽  
Limit Of Detection ◽  
Blue Emission ◽  
World Health ◽  
Selective Determination ◽  
N Doping ◽  
Health Organization ◽  
Doped Carbon Dots ◽  
Nitrogen Doped Carbon

This work reports nitrogen-doped carbon dots (NCDs) as a selective sensing probe to detect Fe3+ in water samples. NCD probes were synthesized via solvothermal method using nitrogen-rich melamine and triethanolamine as precursors. Properties of the resulting NCDs were studied using different characterization techniques, through which N-doping was confirmed. The quantum yield of obtained NCDs was measured to be 21%. When excited at 370 nm, the excellent blue emission property makes this probe adoptable for selectively sensing Fe3+ in practical water samples. The limit of detection (LOD) was identified as 216 nM with a good linear range between the concentrations of 0.2-2 μM. The obtained LOD is far less than the World Health Organization (WHO) permissible limits of Fe3+ in water. Interference studies reveal that the presence of other competing ions did not alter the sensing of Fe3+, even at the presence of 10 equivalents which indicates the high selectivity of NCDs towards Fe3+. The reversibility studies showed that adding a cheap and readily available EDTA ligand to the NCD results in fluorescence regeneration, leading to exceptional reusability for the detection of Fe3+. So, the synthesized NCDs can be used as a suitable probe for the selective determination of Fe3+ in real water samples.

A green one-pot synthesis of nitrogen and sulfur co-doped carbon quantum dots for sensitive and selective detection of cephalexin

2017 ◽  
Vol 95 (6) ◽  
pp. 641-648 ◽  
Author(s):  
Farhad Akhgari ◽  
Naser Samadi ◽  
Khalil Farhadi ◽  
Mehrdad Akhgari
Keyword(s):  
Quantum Dots ◽  
Carbon Dots ◽  
Limit Of Detection ◽  
Carbon Quantum Dots ◽  
Water Soluble ◽  
Soluble Nitrogen ◽  
Selective Detection ◽  
Photoluminescence Intensity ◽  
Doped Carbon Dots ◽  
Co Doped

The article reports a simple, economic, and green method for preparing water-soluble, nitrogen and sulfur co-doped carbon quantum dots via a one-step hydrothermal method. Pomegranate juice served as the carbon source, and the L-cysteine provided nitrogen and sulfur. Co-doped carbon dots were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy techniques. The co-doped carbon dots served as fluorescent probes for sensitive and selective detection of cephalexin. Briefly, the co-doped carbon dot systems showed quenching of photoluminescence intensity in the presence of cephalexin. The decrease of fluorescence intensity made it possible to analyze cephalexin with satisfactory detection limits and linear ranges. The Sterne–Volmer plot showed a linear relationship (R2 = 0.998) between F0/F and the concentration of cephalexin over the range from 0.3 to 10 μmol L−1. The limit of detection (LOD) was estimated to be 1 × 10−7 mol L−1 (at a signal to noise ratio of 3). To validate the applicability, the described method was successfully applied for the detection of cephalexin in human urine and raw milk samples.

Highly Photoluminescent Carbon Dots with pH-Dependent Switchable Fluorescence and Sensitivity to Tetracycline

NANO ◽  
2021 ◽  
pp. 2150036
Author(s):  
Chengwei Wang ◽  
Lei Li ◽  
Yamin Wu ◽  
Jiao Gu ◽  
Chaoqun Ma ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Water Solubility ◽  
Ph Value ◽  
Limit Of Detection ◽  
Temperature Stability ◽  
High Quantum Yield ◽  
Light Stability ◽  
One Step ◽  
Doped Carbon Dots ◽  
Nitrogen Doped Carbon

In this paper, multifunctional nitrogen-doped carbon dots (N-CDs) were synthesized from 3,5-diaminobenzonitrile by a simple one-step hydrothermal method. The N-CDs have a high quantum yield of 67.0% in ethanol with great water solubility, temperature stability, light stability and resistance to ion interference. Experiments showed that pH has an effect on the fluorescence intensity and emission wavelength of N-CDs. Especially, the switchable fluorescence of N-CDs caused by changes of pH value could be distinguished to the naked eye. Additionally, the multifunctional N-CDs also showed a selective response to tetracycline. We studied the influence of tetracycline on the luminescence intensity of N-CDs in the concentration range of 0–1000[Formula: see text][Formula: see text]g/L. A linear equation was established in the range of 10–80[Formula: see text][Formula: see text]g/L with a limit of detection (LOD) of 3.5[Formula: see text][Formula: see text]g/L. Based on the above excellent characteristics, N-CDs are expected to be applied in the field of sensing.

Nitrogen and Sulfur Co-doped Fluorescent Carbon Dots for the Detection of Morin and Cell Imaging

2018 ◽  
Vol 15 (1) ◽  
pp. 47-55
Author(s):  
Xuebing Li ◽  
Haifen Yang ◽  
Ning Wang ◽  
Tijian Sun ◽  
Wei Bian ◽  
...  
Keyword(s):  
Microwave Heating ◽  
Fluorescent Probe ◽  
Fluorescence Intensity ◽  
Carbon Dots ◽  
Cell Imaging ◽  
Water Soluble ◽  
Heating Process ◽  
X Ray ◽  
Doped Carbon Dots ◽  
Co Doped

Background: Morin has many pharmacological functions including antioxidant, anticancer, anti-inflammatory, and antibacterial effects. It is commonly used in the treatment of antiviral infection, gastropathy, coronary heart disease and hepatitis B in clinic. However, researches have shown that morin is likely to show prooxidative effects on the cells when the amount of treatment is at high dose, leading to the decrease of intracellular ATP levels and the increase of necrosis process. Therefore, it is necessary to determine the concentration of morin in biologic samples. Method: Novel water-soluble and green nitrogen and sulfur co-doped carbon dots (NSCDs) were prepared by a microwave heating process with citric acid and L-cysteine. The fluorescence spectra were collected at an excitation wavelength of 350 nm when solutions of NSCDs were mixed with various concentrations of morin. Results: The as-prepared NSCDs were characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The fluorescence intensity of NSCDs decreased significantly with the increase of morin concentration. The fluorescence intensity of NSCDs displayed a linear response to morin in the concentration 0.10-30 μM with a low detection limit of 56 nM. The proposed fluorescent probe was applied to analysis of morin in human body fluids with recoveries of 98.0-102%. Conclusion: NSCDs were prepared by a microwave heating process. The present analytical method is sensitive to morin. The quenching process between NSCDs and morin is attributed to the static quenching. In addition, the cellular toxicity on HeLa cells indicated that the as-prepared NSCDs fluorescent probe does not show obvious cytotoxicity in cell imaging. Our proposed method possibly opens up a rapid and nontoxic way for preparing heteroatom doped carbon dots with a broad application prospect.

scholarly journals TWO-STEP CROSSLINKING OF PVP/GEL NANOFIBERS

2021 ◽  
Vol 2021 ◽  
pp. 164-170
Author(s):  
H.K. Güler ◽  
F.C. Çallıoğlu
Keyword(s):  
Fiber Diameter ◽  
Experimental Studies ◽  
Water Soluble ◽  
Diameter Distribution ◽  
Sem Images ◽  
Crosslinking Process ◽  
Different Temperatures ◽  
Ft Ir ◽  
Ir Analysis ◽  
Gel Polymers

In this study, it was achieved that crosslinking of PVP/GEL nanofibers with two-steps. Crosslinking is a process highly important for water-soluble polymers in terms of application areas and mechanical properties. Firstly, crosslinking of PVP polymers experimental studies were carried out via heat treatment at different temperatures and times. Then, GEL polymers were crosslinked with GTA vapour at different times. Morphological analysis was carried out via SEM images and chemical characteristics were determined via FT-IR analysis. Moreover, after the crosslinking process, SD and WL values were calculated. All results showed that before crosslinking of SEM images, nanofibers were smooth, fine and without beads. The average fiber diameter is 196 nm and the fiber diameter distribution is quite uniform. After crosslinking of SEM images, it is expected that all nanowebs will turn from fibrous surfaces to membranous. Generally, SD and WL values decrease with crosslinking time increase. According to all of the SEM images, SD and WL values, optimum conditions were determined for PVP as 4 hours at 180oC and for GEL as 24 hours. Lastly, the presence of PVP and GEL polymers in the nanofiber structure was verified chemically with FT-IR analysis.

High quantum yield photoluminescent N-doped carbon dots for switch sensing and imaging

Talanta ◽  
2021 ◽  
Vol 222 ◽  
pp. 121663 ◽  
Author(s):  
Zhihui Yi ◽  
Ximing Li ◽  
Hongyu Zhang ◽  
Xiuling Ji ◽  
Wei Sun ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Carbon Dots ◽  
High Quantum Yield ◽  
High Quantum ◽  
Doped Carbon Dots

scholarly journals Highly Photoluminescent and Stable N-Doped Carbon Dots as Nanoprobes for Hg2+ Detection

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 900 ◽  
Author(s):  
Longshi Rao ◽  
Yong Tang ◽  
Hanguang Lu ◽  
Shudong Yu ◽  
Xinrui Ding ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Carbon Dots ◽  
Limit Of Detection ◽  
Energy Levels ◽  
Orbital Energy ◽  
Synthesis Conditions ◽  
Porous Copper ◽  
Different Response ◽  
Doped Carbon Dots ◽  
Nitrogen Doped Carbon

We developed a microreactor with porous copper fibers for synthesizing nitrogen-doped carbon dots (N-CDs) with a high stability and photoluminescence (PL) quantum yield (QY). By optimizing synthesis conditions, including the reaction temperature, flow rate, ethylenediamine dosage, and porosity of copper fibers, the N-CDs with a high PL QY of 73% were achieved. The PL QY of N-CDs was two times higher with copper fibers than without. The interrelations between the copper fibers with different porosities and the N-CDs were investigated using X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR). The results demonstrate that the elemental contents and surface functional groups of N-CDs are significantly influenced by the porosity of copper fibers. The N-CDs can be used to effectively and selectively detect Hg2+ ions with a good linear response in the 0~50 μM Hg2+ ions concentration range, and the lowest limit of detection (LOD) is 2.54 nM, suggesting that the N-CDs have great potential for applications in the fields of environmental and hazard detection. Further studies reveal that the different d orbital energy levels of Hg2+ compared to those of other metal ions can affect the efficiency of electron transfer and thereby result in their different response in fluorescence quenching towards N-CDs.

scholarly journals Green Synthesis of Carbon Dots from Grapefruit and Its Fluorescence Enhancement

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Xinzhu Huo ◽  
Yuxuan He ◽  
Shiqi Ma ◽  
Yingying Jia ◽  
Jiaming Yu ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Carbon Sources ◽  
Carbon Quantum Dots ◽  
One Pot ◽  
Transmission Electron ◽  
Three Samples ◽  
Structure Morphology ◽  
Ir Transmission ◽  
Ft Ir ◽  
Doped Carbon Dots

In this study, undoped carbon quantum dots (UCQDs, UCQDs-peel) and N-doped carbon dots (NCQDs) were prepared by a facile one-pot environmentally friendly hydrothermal method using grapefruit as carbon sources in the absence and presence of area, respectively. The structure, morphology, and fluorescence properties of three samples were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and photoluminescence (PL). It was found that three types of CQDs could emit blue fluorescence with different intensities when irradiated with ultraviolet light. Compared to the luminescence properties of UCQDs, NCQDs, and UCQDs-peel, it can be seen that the fluorescence intensity of NCQDs was strongest due to the presence of NH and C-N bonds.

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