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Copper nanoclusters @ nitrogen-doped carbon quantum dots-based ratiometric fluorescence probe for lead (II) ions detection in porphyra
摘要： A novel ratiometric fluorescence probe was proposed for detecting lead (II) ions (Pb2+) in porphyra, the approach was based on copper nanoclusters and nitrogen-doped carbon quantum dots (CuNCs-CNQDs). In this probe, the CuNCs delivered the response signal, the fluorescence of which was enhanced by Pb2+ due to the aggregation-induced emission enhancement (AIEE) between Pb2+ and CuNCs. The CNQDs provided the self-calibration signal, whose fluorescence remained almost unchanged in coexistence with Pb2+. According to the change of fluorescence intensity ratio between the fluorophores, CuNCs–CNQDs nanohybrid was used as ratiometric probes for the sensitive detection of Pb2+ in the range of 0.010 to 2.5 mg L-1, with a detection limit of 0.0031 mg L-1. Finally, the probe was successfully applied to detect Pb2+ in porphyra with relative standard deviations (RSDs) lower than 5%. This study provides a straightforward, stable, and sensitive approach for detecting Pb2+ in porphyra.
关键词： Lead (II) ions,Ratiometric fluorescence probe,Aggregation-induced emission enhancement,Copper nanoclusters,Nitrogen-doped carbon quantum dots
更新于2025-09-23 15:21:01
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Fluorescent-Nitrogen-Doped Carbon Quantum Dots Derived from Citrus Lemon Juice: Green Synthesis, Mercury(II) Ion Sensing, and Live Cell Imaging
摘要： In this study, we report a green and economical hydrothermal synthesis of fluorescent-nitrogen-doped carbon quantum dots (NCQDs) using citrus lemon as a carbon source. The prepared NCQDs possess high water solubility, high ionic stability, resistance to photobleaching, and bright blue color under ultraviolet radiation with a high quantum yield (～31%). High-resolution transmission electron microscopy (HRTEM) results show that the prepared NCQDs have a narrow size distribution (1?6 nm) with an average particle size of 3 nm. The mercury ion (Hg2+) sensing efficiency of the NCQDs was studied, and the result indicated that the material has high sensitivity, high precision, and good selectivity for Hg2+. The limit of detection (LOD) is 5.3 nM and the limit of quantification (LOQ) is 18.3 nM at a 99% confidence level. The cytotoxicity was evaluated using MCF7 cells, and the cell viabilities were determined to be greater than 88% upon the addition of NCQDs over a wide concentration range from 0 to 2 mg/mL. Based on the low cytotoxicity, good biocompatibility, and other revealed interesting merits, we also applied the prepared NCQDs as an effective fluorescent probe for multicolor live cell imaging.
关键词： mercury(II) ion sensing,citrus lemon juice,green synthesis,live cell imaging,fluorescent-nitrogen-doped carbon quantum dots
更新于2025-09-23 15:19:57
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S, N-doped carbon quantum dots enhanced Luminol-Mn(IV) chemiluminescence reaction for detection of uric acid in biological fluids
摘要： Herein, S, N doped carbon quantum dots (S, N- CQDs) were prepared by a simple hydrothermal method and characterized by transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FTIR) analysis. The influence of as-prepared CQDs was studied on the luminol- Mn(IV) CL reaction. The results indicated that S, N-CQDs remarkably increase the CL intensity of this reaction (about 13 fold). Furthermore, it was found that the CL intensity of S,N-CQDs–luminol-Mn(IV) system was significantly declined by uric acid. We exploited the amplified CL system to design a novel probe for the detection of uric acid. The CL intensity of S,N-CQDs–luminol-Mn(IV) reaction was proportional to the logarithm of uric acid concentration in the range of 0.05 to 1.5 μM, with a limit of detection of 17 nM. Based on these results, a sensitive and straightforward CL method was developed for the analysis of uric acid in biological fluids with satisfactory results.
关键词： Uric acid,sulfur-nitrogen doped carbon quantum dots,Chemiluminescence,Mn (IV)
更新于2025-09-23 15:19:57
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Gadolinium-doped carbon quantum dots loaded magnetite nanoparticles as a bimodal nanoprobe for both fluorescence and magnetic resonance imaging
摘要： Nowadays, it is highly desired to develop dual-modal fluorescence and magnetic resonance imaging (FI/MRI) probes in medical imaging because it unites the respective advantages of each imaging modality: high sensitivity of FI and superior spatial resolution of MRI. In this study, a facile strategy to fabricate a new bimodal imaging nanoprobe (Gd-CQDs@N-Fe3O4) was reported by integrating the fluorescence ability of carbon quantum dots (CQDs) and T1 and T2 contrast-enhancing functionality of Gd(Ⅲ) ions and Fe3O4 nanoparticles into a single hybrid nanostructure. The hybrid composites were investigated by FT-IR, XRD, TEM, XPS, VSM, and so on, which confirmed that Gd-CQDs@N-Fe3O4 nanoparticles were successfully obtained and exhibited superparamagnetic property at room temperature. The derived nanoprobes presented an excitation wavelength-independent emission behavior. In addition, r1 and r2 relaxivities of the synthesized imaging nanoprobes were measured to be 5.16 and 115.6 mM-1 s-1, which nominated Gd-CQDs@N-Fe3O4 nanocomposites as a suitable T1-T2 contrast agent. The Gd-CQDs@N-Fe3O4 nanoparticles combining two synergetic imaging modalities showed great potential in FI/MRI dual-modal imaging for a more complementary and accurate detection.
关键词： Gd-doped carbon quantum dots,Fluorescence,Fe3O4,Relaxivity,Dual-modal imaging
更新于2025-09-19 17:13:59
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Precise Surface State Control of Carbon Quantum Dots to Enhance Charge Extraction for Solar Cells
摘要： Dye‐sensitized solar cells are regarded as promising candidates to resolve the energy and environmental issues in recent years, arising from their solution‐processable fabrication technology and high power conversion efficiency. However, there are still several problems regarding how to accelerate the development of this type of photovoltaics, including the limited light‐harvesting ability and high‐production cost of molecular dye. In the current work, we have systematically studied the role of nitrogen‐doped carbon quantum dots (N‐CQDs) as co‐sensitizers in traditional dye sensitized solar cells. A series of N‐CQDs have been prepared by employing chitosan as a precursor via one‐pot hydrothermal technology for various times, demonstrating a maximized efficiency as high as 0.089% for an only N‐CQDs‐based device. Moreover, the co‐sensitized solar cell based on N719 dye (C58H86N8O8RuS2) and optimized N‐CQDs shows significantly enhanced performance, yielding a solar‐to‐electric conversion efficiency of up to 9.15% under one standard sun (AM 1.5G) irradiation, which is much higher than the 8.5%‐efficiency of the controlled device without N‐CQDs. The matched characteristics of energy level, excellent up‐convention, and FRET (F?rster resonance energy transfer) abilities of N‐CQDs are responsible for their improved power conversion efficiency.
关键词： light absorption,up‐convention,nitrogen‐doped carbon quantum dots,co‐sensitized solar cell
更新于2025-09-19 17:13:59
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Novel N/Carbon Quantum Dots-Modified MIL-125(Ti) Composite for Enhanced Visible Light Photocatalytic Removal of NO
摘要： A highly efficient and stable photocatalysts were synthesized at room temperature by modifying MIL-125(Ti) with N-doped carbon quantum dots (N/CM(Ti)). The N/CM(Ti) with 2.5 Vol% N doped carbon quantum dots (N/CQDs) had the best light absorption and visible light photocatalytic nitrogen oxide (NO) removal efficiency (approximately 49%). It was found through X-ray photoelectron spectroscopy analysis that the N-Ti-O bond was formed in the 2.5 Vol% N/CM(Ti), which is more conducive to charge transfer. Photocurrent and electrochemical impedance data also showed that the carrier separation efficiency of 2.5 Vol% N/CM(Ti) was significantly superior to that of MIL-125(Ti). In addition, the TiIII-TiIV of MIL-125(Ti) acts as the active center for photocatalytic removal of NO. Two possible electron migration paths were proposed: electron transfer from N/CQDs to TiIII-TiIV center of MIL-125(Ti) due to the photoinduced electron transfer property of N/CQDs, and absorption of UV light generated from the N/CQDs by the terephthalic acid ligand followed by electron transfer to metal active sites for photocatalytic removal of NO.
关键词： MIL-125(Ti),Visible light,Photocatalysis,NO removal,N-doped carbon quantum dots
更新于2025-09-19 17:13:59
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Layer by Layer Self-Assembly of Hollow Nitrogen-Doped Carbon Quantum Dots on Cationized Textured Crystalline Silicon Solar Cells for Efficient Energy Down-Shift
摘要： Enhancing the efficiency of crystalline silicon solar cell (c-Si SC) by coating the energy shifting layer of quantum dots (QDs) is a recent approach to efficiently utilize the high energy spectrum of light. Carbon QDs are an attractive candidate for such applications, however, small Stokes shift and non-uniform coating due to high aggregation are the bottlenecks to fully utilize their potential. For the purpose, here we propose a layer by layer self-assembled uniform coating of ecofriendly red-emissive hollow nitrogen-doped carbon QDs (NR-CQDs), as an efficient energy-down shifting layer. A unique hollow and conjugated structure of NR-CQDs was designed to achieve a large Stokes shift (UV excited - red emission), with a quantum yield (QY) comparable to Cd/Pb QDs. Highly uniform coating of intrinsically negatively charged NR-CQDs on c-Si SCs was achieved by cationizing the c-Si SC by Bovine serum albumin (BSA), under mildly acidic conditions. By opposite charge assisted self-assembled over-layer, the short-circuit current density (Jsc) and power-conversion efficiency was increased by 5.8%, which is attributed to the large Stokes shift (255 nm) and high QY. Blue-emissive undoped-carbon QDs were synthesized for comparison with the proposed NR-CQDs, to elucidate the significance of the novel proposed structure.
关键词： energy-downshift,crystalline silicon solar cells,layer by layer self-assembly,Nitrogen-doped carbon quantum dots,cationization,photoluminescence
更新于2025-09-19 17:13:59
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Red-emissive nitrogen doped carbon quantum dots for highly selective and sensitive fluorescence detection of the alachlor herbicide in soil samples
摘要： Red-emissive nitrogen doped carbon quantum dots (N-CQDs) were synthesized by a facile and efficient microwave-assisted hydrothermal treatment of p-phenylenediamine (p-PD), and then applied for the highly selective and sensitive fluorescence detection of the alachlor herbicide in soil samples. The synthesized N-CQDs exhibited strong red emission with a 27.6% quantum yield (QY) and high stability. Under the optimized experimental conditions, the as-prepared red-emissive N-CQDs were employed as a fluorescent probe to successfully detect trace alachlor, and their fluorescence presented a good linear decline with the increase of the alachlor concentration from 0.005 to 150 mM with a limit of detection of 0.2 nM. The N-CQDs as a fluorescent probe were used for the detection of alachlor in soil samples with satisfactory recoveries ranging from 86.6–114.3%, indicating that they were a promising fluorescent probe for highly selective and sensitive determination of alachlor.
关键词： soil samples,Red-emissive nitrogen doped carbon quantum dots,fluorescence detection,alachlor herbicide
更新于2025-09-16 10:30:52
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Rapid synthesis of B-N co-doped yellow emissive carbon quantum dots for cellular imaging
摘要： In order to avoid the interference of autofluorescence and improve tissue penetration capability of carbon quantum dots (CQDs) in biological imaging, the synthesis of long-wavelength emission CQDs was achieved in this work. Boron and nitrogen co-doped CQDs (BN-CQDs) were synthesized by one-step microwave assisted hydrothermal method with o-phenylenediamine as carbon and nitrogen source, boric acid as boron source. The BN-CQDs (QY ? 13.79%) synthesized under the optimal conditions exhibit excitation independence, a large Stoke shift, satisfactory fluorescent stability, good biocompatibility and low toxicity, which can meet the basic requirements as cell imaging agent. Cell imaging measurements prove their increased intracellular accumulation with the extension of incubation time with HeLa cells, and clearly observable BN-CQDs imaging for cell morphology. Hence BN-CQDs can be used as a good cell imaging agent.
关键词： Rapidity,Cellular imaging,Yellow emission,B-N co-doped carbon quantum dots
更新于2025-09-16 10:30:52
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Ethanol-Precipitation-Assisted Highly Efficient Synthesis of Nitrogen-Doped Carbon Quantum Dots from Chitosan
摘要： Nitrogen-doped carbon quantum dots (NCQDs) were prepared from chitosan through a hydrothermal reaction. When ethanol precipitation was used as the puri?cation method, a high product yield of 85.3% was obtained. A strong blue ?uorescence emission with a high quantum yield (QY) of 6.6% was observed from the NCQD aqueous solution. Physical and chemical characteristics of the NCQDs were carefully investigated by transmission electron microscopy (TEM), X-ray di?raction (XRD), Fourier transform infrared spectra (FTIR), Raman spectra, X-ray photoelectron spectroscopy (XPS), and transient ?uorescence spectra. Experimental results showed that diameters of the NCQDs were in the range of 2?10 nm. The carbon quantum dots possess good water dispersibility and precipitation by ethanol. When used for metal ion detection, the detection limit of the NCQDs for Fe3+ was as low as 1.57 μM. This work proposed a facile method to synthesize NCQDs from chitosan with high yield and demonstrated that carbon quantum dots derived from chitosan were promising for ion detection.
关键词： ethanol precipitation,metal ion detection,chitosan,hydrothermal reaction,Nitrogen-doped carbon quantum dots
更新于2025-09-12 10:27:22