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Green Preparation of Fluorescent Carbon Quantum Dots from Cyanobacteria for Biological Imaging
摘要： Biomass-based carbon quantum dots (CQDs) have become a significant carbon materials by their virtues of being cost-effective, easy to fabricate and low in environmental impact. However, there are few reports regarding using cyanobacteria as a carbon source for the synthesis of fluorescent CQDs. In this study, the low-cost biomass of cyanobacteria was used as the sole carbon source to synthesize water-soluble CQDs by a simple hydrothermal method. The synthesized CQDs were mono-dispersed with an average diameter of 2.48 nm and exhibited excitation-dependent emission performance with a quantum yield of 9.24%. Furthermore, the cyanobacteria-derived CQDs had almost no photobleaching under long-time UV irradiation, and exhibited high photostability in the solutions with a wide range of pH and salinity. Since no chemical reagent was involved in the synthesis of CQDs, the as-prepared CQDs were confirmed to have low cytotoxicity for PC12 cells even at a high concentration. Additionally, the CQDs could be efficiently taken up by cells to illuminate the whole cell and create a clear distinction between cytoplasm and nucleus. The combined advantages of green synthesis, cost-effectiveness and low cytotoxicity make synthesized CQDs a significant carbon source and broaden the application of cyanobacteria and provide an economical route to fabricate CQDs on a large scale.
关键词： bioimaging,cyanobacteria,carbon quantum dots,hydrothermal method
更新于2025-11-21 11:08:12
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Facile Synthesis of Luffa Sponge Activated Carbon Fiber Based Carbon Quantum Dots with Green Fluorescence and Their Application in Cr(VI) Determination
摘要： Carbon quantum dots (CQDs) were prepared by a chemical oxidation method using lu?a sponge based activated carbon ?ber as the raw material. The obtained CQDs were well characterized. The ?uorescence quenching e?ect of Cr(VI) ion on CQDs was investigated. The results show that the addition of Cr(VI) changes the intensity of the ultraviolet characteristic absorption peak of CQDs, and causes static quenching of the ?uorescence of CQDs. With the increase in the Cr(VI) concentration, the ?uorescence of CQDs was gradually extinguished linearly.
关键词： Activated carbon ?ber,Lu?a sponge,Cr(VI) determination,Fluorescence quenching,Carbon quantum dots
更新于2025-11-21 11:01:37
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Carbon quantum dots/TiO2 nanosheets with dominant (001) facets for enhanced photocatalytic hydrogen evolution
摘要： Carbon quantum dots/TiO2 nanosheets with a majority of (001) facet (CQDs/TiO2-001) samples are successfully prepared via a facile method. Compared to TiO2-001 and CQDs/P25, the synthesized CQDs/TiO2-001 presents a remarkably higher photocatalytic activity for H2 evolution with a considerable stability. XRD, XPS, HRTEM, FESEM, FTIR, Photoluminescence (PL) spectroscopy, Fluorescence spectroscopy and UV–visible reflectance spectroscopy are adopted to investigate the morphology, structure and properties of synthesized CQDs/TiO2-001. The mechanism of the improved photocatalytic activity over CQDs/TiO2-001 is also investigated. The results show that the improved photocatalytic activity over CQDs/TiO2-001 can be attributed to the synergistic effects of TiO2-001 and CQDs: the highly exposed (001) facets of TiO2-001 promote the transportation of photogenerated electrons and the loading of CQDs restrains the recombination of electrons-holes on (001) facets. Meanwhile, the visible-light absorption is extended because the CQDs serve as a photosensitizer and sensitize TiO2-001 through the newly formed TieOeC bond between the CQDs and TiO2-001.
关键词： Carbon quantum dots,TiO2,Photocatalytic H2 evolution,(001) facet
更新于2025-11-21 11:01:37
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Synthesis of carbon quantum dots from lac dye for silicon dioxide imaging and highly sensitive ethanol detecting
摘要： This study aimed to improve the fluorescence performance of lac dye by preparing carbon quantum dots in an attempt to diversify the applicability of lac dye in fluorescence detection. The highly photoluminescent (PL) ld-CQDs were synthesized for the first time using lac dye as a precursor by a facile, green, one-pot ethanol thermal method. The ld-CQDs were neither soluble nor dispersed in water, but could be dissolved or dispersed in organic solvents. The ld-CQDs were well dispersed in ethanol with a mean diameter of 1.76 nm and were found to emit a bright yellow fluorescence with an emission wavelength of 570 nm. The quantum yield of ld-CQDs was 0.40, which was a significant 20-fold improvement over the lac dye of 0.02. Meanwhile, ld-CQDs exhibited pH-sensitive and excellent affinity for silicon dioxide without further chemical modification. Further, ld-CQDs could be used to image silicon dioxide since the fluorescence intensity of the ld-CQDs/silicon dioxide composites was significantly improved. Furthermore, the ld-CQDs could be used as a highly sensitive fluorescent probe to detect the ethanol content of commercial wines. In conclusion, this study has demonstrated the novel application of the fluorescence properties of the lac dye, which has utility in visual detection applications and in tracking the detection of silicon dioxide and ethanol.
关键词： novel application,carbon quantum dots,photoluminescent,Lac dye
更新于2025-11-20 15:33:11
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Photoluminescence enhancement <i>via</i> microwave irradiation of carbon quantum dots derived from solvothermal synthesis of <scp>l</scp> -arginine
摘要： Photoluminescence enhancement of carbon quantum dots was achieved via solvothermal synthesis followed by microwave irradiation. Nitrogen and phosphorous doped carbon quantum dots were prepared by solvothermal heating of L-arginine with phosphoric acid for 12 hours followed by microwave irradiation for 3 minutes. The photoluminescence enhancement was nearly two fold after microwave irradiation. The morphology, structure, and surface properties were the same for the solvothermal (CQDs-S) as well as after microwave (CQDs-M) irradiation. Thus, the enhancement is attributed to the decrease of surface defects within CQDs, which led to a decrease in the non-radiative transitions. The CQDs were quenched selectively by Fe3+ ions. The quenching led to the fabrication of the fluorescence probe for ferric ion determination. The CQDs-M had a low detection limit of 4.0 nM, while CQDs-S had a limit of 50 nM. This study gives a tool for enhancing photoluminescence quantum yields, which is highly desired for biosensing and bioimaging applications.
关键词： Photoluminescence enhancement,Fluorescence probe,Solvothermal synthesis,Ferric ion determination,Microwave irradiation,Carbon quantum dots
更新于2025-11-19 16:56:42
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Valorization of tire wastes to carbon quantum dots (P-CDs) and photocatalytic degradation enhancement of organic wastes using ZnO-CDs nanocomposites
摘要： Valorization of solid wastes for the production of valuable materials is of great importance for sustainable development. In this paper, removal for solid and liquid wastes via hydrothermal and catalytic degradation was reported. The first removal process is the hydrothermal conversion of solid waste, here solid wastes of tire, to phosphorous and nitrogen doped carbon nanodots (P-CDs). The second removal is the visible-NIR light driven photocatalytic degradation of liquid waste, here methylene blue (MB) solution, using P-CDs loaded on ZnO nanoparticles. Energy-efficient light emitting diode (LED) was used as a weak sufficient irradiation source. Photodegradation rate constants for ZnO-P-CDs were almost 10 times higher (0.08 h?1 for ZnO-P-CDs) comparing to pure ZnO (0.008 h?1), such enhancement is significant for a weak light source. Cyclic voltammetry and optical properties were used to find HOMO and LUMO of P-CDs. Based on the energy levels of ZnO and P-CDs, the catalytic enhancement was attributed to increasing the separation rate of photogenerated electrons and hole due to the transfer of electrons from the conduction bands of P-CDs to the conduction band of ZnO. Up-conversion photoluminescence of P-CDs is another reason for increasing the separation of excitons and harvesting the longer wavelength light. The proposed approach, solid and liquid waste removal via hydrothermal and catalytic degradation combined with weak LED light, would be a powerful approach in solid waste treatment and water purification technology, simultaneously.
关键词： Valorization,Tire wastes,Carbon quantum dots,Photocatalytic degradation,ZnO-P-CDs nanocomposites
更新于2025-11-19 16:56:42
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Facile ultrasonic synthesized NH2-carbon quantum dots for ultrasensitive Co2+ ion detection and cell imaging
摘要： The amine decorated carbon quantum dots (NH2-CQDs) were synthesized through ultrasonic method from graphite rods derived CQDs and ammonia hydroxide and utilized as the sensing probes for cobalt (II) ions and nucleic acids. The sensing technique was investigated to be the fluorescence quenching effect, which demonstrated linear relationship between cobalt (II) ions concentration and the emission intensity deviation ratio in the concentration range of 50 nM to 40 μM with the detection limit of 12 nM. In brief, this sensitive and selective detection method was confirmed to demonstrate high potential in cobalt (II) ions detection in real samples and nucleic acid sensing in biological cells.
关键词： Nucleic acid sensing,Carbon quantum dots (CQDs),Cobalt sensor
更新于2025-11-19 16:56:42
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Facile preparation of boron and nitrogen co-doped green emission carbon quantum dots for detection of permanganate and captopril
摘要： A hydrothermal strategy for preparing boron and nitrogen co-doped carbon quantum dots was studied using the precursors of p-amino salicylic acid, boric acid and ethylene glycol dimethacrylate. The boron and nitrogen co-doped carbon quantum dots have high fluorescence intensity, good monodispersity, high stability, superior water solubility, and a fluorescence quantum yield of 19.6%. Their average size is 5 nm. Their maximum excitation and emission wavelengths are 380 nm and 520 nm, respectively. Permanganate (MnO4-) quenched boron and nitrogen co-doped carbon quantum dots fluorescence through inner filter effect and static quenching effects. The linear relation between quenching efficiency and MnO4- concentration ranged from 0.05 to 60 μmol/L with a detection limit of 13 nmol/L. In the presence of captopril, MnO4- was reduced to Mn2+ and the fluorescence of boron and nitrogen co-doped carbon quantum dots was recovered. The linear range between recovery and captopril concentration was from 0.1 to 60 μmol/L. The limit of detection was 0.03 μmol/L. The developed method can be employed as a sensitive fluorescence sensing platform for MnO4-. It has been successfully used for captopril detection in mouse plasma.
关键词： Captopril,Plasma,Fluorescence,Potassium permanganate,Carbon quantum dots
更新于2025-11-19 16:56:42
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The Application of Green-Synthesis-Derived Carbon Quantum Dots to Bioimaging and the Analysis of Mercury(II)
摘要： Ginkgo leaves were used as precursors for the hydrothermal synthesis of carbon quantum dots (CQDs), which were subsequently characterized by transmission electron microscopy as well as Fourier-transform infrared, X-ray powder di?raction, and X-ray photoelectron spectroscopy. The prepared CQDs exhibited a ?uorescence quantum yield of 11% and superior water solubility and ?uorescence stability, as well as low cytotoxicities and excellent biocompatibilities with A549 and HeLa cells; these CQDs were also used to bioimage HeLa cells. Moreover, owing to the experimental observation that Hg2+ quenches the ?uorescence of the CQDs in a speci?c and sensitive manner, we developed a method for the detection of Hg2+ using this ?uorescence sensor. The sensor exhibited a linear range for Hg2+ of 0.50–20 μM, with an excellent coe?cient of determination (R2 ? 0.9966) and limit of detection (12.4 nM). In practice, the proposed method was shown to be highly selective and sensitive for the monitoring of Hg2+ in lake water and serum samples.
关键词： mercury(II) detection,carbon quantum dots,hydrothermal synthesis,fluorescence quenching,bioimaging
更新于2025-11-19 16:46:39
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Enhancing photoluminescence of carbon quantum dots doped PVA films with randomly dispersed silica microspheres
摘要： As a kind of excellent photoluminescent material, carbon quantum dots have been extensively studied in many fields, including biomedical applications and optoelectronic devices. They have been dispersed in polymer matrices to form luminescent films which can be used in LEDs, displays, sensors, etc. Owing to the total internal reflection at the flat polymer/air interfaces, a significant portion of the emitted light are trapped and dissipated. In this paper, we fabricate free standing flexible PVA films with photoluminescent carbon quantum dots embedded in them. We disperse silica microspheres at the film surfaces to couple out the total internal reflection. The effects of sphere densities and diameters on the enhancement of photoluminescence are experimentally investigated with a homemade microscope. The enhancement of fluorescence intensity is as high as 1.83 when the film is fully covered by spheres of 0.86 μm diameter. It is worth noting that the light extraction originates from rather the scattering of individual spheres than the diffraction of ordered arrays. The mechanism of scattering is confirmed by numerical simulations. The simulated results show that the evanescent wave at the flat PVA/air interface can be effectively scattered out of the film.
关键词： silica microspheres,light extraction,photoluminescence,PVA films,carbon quantum dots
更新于2025-11-19 16:46:39