scispace - formally typeset
Journal ArticleDOI: 10.1016/J.SAA.2020.119282

Hydrothermal synthesis of N-doped carbon quantum dots and their application in ion-detection and cell-imaging

Abstract: Carbon quantum dots (CQDs), owing to their characteristic luminescent properties, have become a new favorite in the field of luminescence. They have been widely used in light emitting diode, ion detection, cell-imaging, ect. Herein a facile synthesis method of nitrogen-doped carbon quantum dots (N-CQDs) has been developed via a one-step hydrothermal of glucose and m-phenylenediamine. The chemical composition, surface functional groups, and crystal structure of so prepared N-CQDs were systematically characterized. The characterizations indicate that nitrogen has been chemically doped in the CQDs and the N-CQDs crystallize in a graphene structure. Photoluminescence (PL) measurements show that the N-CQDs emit strong blue emission under the irradiation of ultraviolet. The emission is excitation-dependent, is resistant to photo bleaching and high ionic strength, and slightly decreases with the increase of temperature. The quantum yield of them is about 17.5%. The PL intensity of N-CQDs quenches linearly with the increase of the concentrations of Fe3+(0.5–1.0 mM) and CrO42−(0.3–0.6 mM), which are a kind of excellent fluorescent probe for the detection of Fe3+ and CrO42−. The quenching mechanism of Fe3+ and CrO42−is verified to be a static quenching mechanism based on inner filter effect. The N-CQDs are also found to be a good cell-imaging reagent of Hela cells.

... read more

Topics: Quantum dot (57%), Photoluminescence (55%), Quantum yield (54%) ... show more

5 results found

Open accessJournal ArticleDOI: 10.3390/CHEMOSENSORS9060138
11 Jun 2021-
Abstract: The fluorescent carbon quantum dots (CQDs) represent an emerging subset of carbonaceous nanomaterials, recently becoming a powerful tool for biosensing, bioimaging, and drug and gene delivery. In general, carbon dots are defined as zero-dimensional (0D), spherical-like nanoparticles with <10 nm in size. Their unique chemical, optical, and electronic properties make CQDs versatile materials for a wide spectrum of applications, mainly for the sensing and biomedical purposes. Due to their good biocompatibility, water solubility, and relatively facile modification, these novel materials have attracted tremendous interest in recent years, which is especially important for nanotechnology and nanoscience expertise. The preparation of the biomass-derived CQDs has attracted growing interest recently due to their low-cost, renewable, and green biomass resources, presenting also the variability of possible modification for the enhancement of CQDs’ properties. This review is primarily focused on the recent developments in carbon dots and their application in the sensing of different chemical species within the last five years. Furthermore, special emphasis has been made regarding the green approaches for obtaining CQDs and nanomaterial characterization toward better understanding the mechanisms of photoluminescent behavior and sensing performance. In addition, some of the challenges and future outlooks in CQDs research have been briefly outlined.

... read more

3 Citations

Journal ArticleDOI: 10.1007/S10895-021-02696-2
Abstract: Carbon quantum dots (CQD) as the result of their exceptional physical and chemical properties show tremendous potential in various field of applications like cell imaging and doping of CQDs with elements like nitrogen and phosphorous increase its fluorescence property. Herein, we have synthesized fluorescent nitrogen and phosphorous codoped carbon quantum dots (NPCQDs) via a one-pot hydrothermal method. Sesame oil, L-Aspartic acid, and phosphoric acid were used as carbon, nitrogen, and phosphorous sources, respectively. UV-Vis spectrophotometer, fluorescence spectrometer, Fourier transform infrared spectrometer (FTIR), X-ray diffraction spectrometer (XRD), field emission scanning microscopy (FESEM), and transmission electron microscopy (TEM) were employed to characterize the synthesized fluorescent NPCQDs. The as-synthesized NPCQDs with a particle size of 4.7 nm possess excellent water solubility, high fluorescence with high quantum yield (46%), high ionic stability, and resistance to photobleaching. MTT assay indicated the biocompatibility of NPCQDs and it was used for multicolor live-cell imaging. Besides, the NPCQDs show an effective probe of iron ions (Fe3+) in an aqueous solution with a high degree of sensitivity and selectivity. The DPPH assay showed its good antioxidant activity.

... read more

Topics: Fourier transform infrared spectroscopy (53%), Photobleaching (51%), Quantum yield (51%) ... show more

2 Citations

Journal ArticleDOI: 10.1088/1361-6528/AC2D07
Chunxing Li1, Wang Yun, Huayan Nong, Hu Xiaoxi1  +5 moreInstitutions (2)
22 Oct 2021-Nanotechnology
Abstract: It has been challenging to integrate various medical imaging modalities into an ultra-small nanoparticle with good biocompatibility to build highly efficient multimodal imaging nanoprobes. A new manganese and dysprosium codoped carbon quantum dots (Mn,Dy-CQDs) with a mean diameter of 1.77 nm was synthesized for fluorescence imaging,T1/T2-weighted magnetic resonance imaging (T1/T2-weighted MRI), and x-ray computed tomography (CT) imaging using a simple one-step hydrothermal approach. The obtained Mn,Dy-CQDs showed good water solubility, long-term stability, strong stable fluorescence property (fluorescence quantum yield of 31.62%), and excellent biocompatibility. The cell imaging verified that the Mn,Dy-CQDs have high efficiency of fluorescence imaging. The Mn,Dy-CQDs, on the other hand, had a superior x-ray absorption performance (47.344 HU l g-1), a higher longitudinal relaxivity (r1 = 7.47 mM-1s-1), a higher transverse relaxivity (r2 = 42.686 mM-1s-1).In vitroT1/T2-weighted MRI and CT imaging showed that Mn,Dy-CQDs can produce a strong contrast enhancement impact. To summarise, the Mn,Dy-CQDs may be used as aT1/T2-weighted MRI/CT/fluorescent quadri-modal imaging nanoprobe, indicating that they have a lot of uses in biomedical multimode imaging and clinics.

... read more

Journal ArticleDOI: 10.1016/J.VACUUM.2021.110648
06 Oct 2021-Vacuum
Abstract: A flexible resistive-type humidity sensor based on N-type nitrogen-doped carbon oxide quantum dots (NCQDs) is presented. The NCQDs were synthesized by using simple hydrothermal method with reactions via citric acid and urea. The UV–vis, FE-TEM and XPS analysis confirm a successful doping of N atoms and existence of oxygen-containing functional groups into carbon quantum dots with the homogeneous spherical structure. The NCQDs humidity sensor exhibits high humidity response, good repeatability, and high stability as well as linear response to humidity in the range of 20–90% RH. The humidity sensing mechanism has been in-depth investigated by self-consistent charge density functional tight-binding (SCC-DFTB) including dispersion interaction. The SCC-DFTB reveals an important role of N doping with physisorption via direct charge transfer sensing mechanism.

... read more

Topics: Quantum dot (51%)

Journal ArticleDOI: 10.1021/ACSNANO.1C03886
24 Sep 2021-ACS Nano
Abstract: Carbon dots have been considered as a solution to the challenges that semiconductor quantum dots have encountered because they are more biocompatible and can be synthesized from abundant and nontoxic materials such as biomass. This review will highlight the advantages of these biomass-based carbon dots in terms of synthesis, properties, and applications in the biomedical field. Furthermore, future applications especially in the biomedical field of biomass-based carbon dots as well as the challenges of semiconductor quantum dots such as biocompatibility, photobleaching, environmental challenges, toxicity, and poor solubility will be discussed in detail. Biomass-derived quantum dots, a subsection of carbon dots that are the most desirable for future research, will be focused upon including from synthesis to applications. Finally, the future development of biomass derived quantum dots in the biomedical field will be discussed and evaluated to unlock the potential for their applications.

... read more

Topics: Quantum dot (51%)

85 results found

Journal ArticleDOI: 10.1021/JA040082H
Xiaoyou Xu1, Robert Ray1, Yunlong Gu1, Harry J. Ploehn1  +3 moreInstitutions (1)
Abstract: Arc-synthesized single-walled carbon nanotubes have been purified through preparative electrophoresis in agarose gel and glass bead matrixes. Two major impurities were isolated: fluorescent carbon and short tubular carbon. Analysis of these two classes of impurities was done. The methods described may be readily extended to the separation of other water-soluble nanoparticles. The separated fluorescent carbon and short tubule carbon species promise to be interesting nanomaterials in their own right.

... read more

Topics: Carbon (56%), Carbon nanotube (55%), Agarose (53%)

2,399 Citations

Journal ArticleDOI: 10.1002/ANIE.201301114
Yongqiang Dong1, Hongchang Pang1, Hongbin Yang1, Chunxian Guo1  +5 moreInstitutions (3)
22 Jul 2013-Angewandte Chemie
Abstract: Helpful elements: A facile bottom-up method using citric acid and L-cysteine as a precursor has been developed to prepare graphene quantum dots (GQDs) co-doped with nitrogen and sulfur. A new type and high density of surface state of GQDs arises, leading to high yields (more than 70 %) and excitation-independent emission. FLQY = fluorescence quantum yield.

... read more

Topics: Quantum yield (56%), Quantum dot (55%), Graphene (53%)

1,563 Citations

Journal ArticleDOI: 10.1021/ACSNANO.5B05406
26 Jan 2016-ACS Nano
Abstract: Carbon dots (CDs) with tunable photoluminescence (PL) and a quantum yield of up to 35% in water were hydrothermally synthesized in one pot and separated via silica column chromatography. These separated CDs emitted bright and stable luminescence in gradient colors from blue to red under a single-wavelength UV light. They exhibited high optical uniformity; that is, every sample showed only one peak in the PL excitation spectrum, only one peak in the excitation-independent PL emission spectrum, and similar monoexponential fluorescence lifetimes. Although these samples had similar distributions of particle size and graphite structure in their carbon cores, the surface state gradually varied among the samples, especially the degree of oxidation. Therefore, the observed red shift in their emission peaks from 440 to 625 nm was ascribed to a gradual reduction in their band gaps with the increasing incorporation of oxygen species into their surface structures. These energy bands were found to depend on the surfac...

... read more

Topics: Luminescence (55%), Emission spectrum (52%), Carbon (50%)

1,230 Citations

Journal ArticleDOI: 10.1002/ANIE.201501193
Kai Jiang1, Shan Sun2, Ling Zhang2, Yue Lu2  +3 moreInstitutions (2)
27 Apr 2015-Angewandte Chemie
Abstract: A facile approach for preparation of photoluminescent (PL) carbon dots (CDs) is reported. The three resulting CDs emit bright and stable red, green and blue (RGB) colors of luminescence, under a single ultraviolet-light excitation. Alterations of PL emission of these CDs are tentatively proposed to result from the difference in their particle size and nitrogen content. Interestingly, up-conversion (UC)PL of these CDs is also observed. Moreover, flexible full-color emissive PVA films can be achieved through mixing two or three CDs in the appropriate ratios. These CDs also show low cytotoxicity and excellent cellular imaging capability. The facile preparation and unique optical features make these CDs potentially useful in numerous applications such as light-emitting diodes, full-color displays, and multiplexed (UC)PL bioimaging.

... read more

Topics: Luminescence (50%)

1,159 Citations

Journal ArticleDOI: 10.1039/C3NR05380F
Zhi Yang1, Xu Minghan1, Liu Yun1, Fengjiao He1  +4 moreInstitutions (1)
16 Jan 2014-Nanoscale
Abstract: The synthesis of water-soluble nitrogen-doped carbon dots has received great attention, due to their wide applications in oxygen reduction reaction, cell imaging, sensors, and drug delivery. Herein, nitrogen-doped, carbon-rich, highly photoluminescent carbon dots have been synthesized for the first time from ammonium citrate under hydrothermal conditions. The obtained nitrogen-doped carbon dots possess bright blue luminescence, short fluorescence lifetime, pH-sensitivity and excellent stability at a high salt concentration. They have potential to be used for pH sensors, cell imaging, solar cells, and photocatalysis.

... read more

Topics: Carbon (55%)

635 Citations