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Smartphone-based three-channel ratiometric fluorescent device and application in filed analysis of Hg2+, Fe3+ and Cu2+ in water samples
摘要： Determination of metal ions in water samples, especially harmful heavy metal like mercury or essential elements like iron and copper, is an important work in environmental monitoring. Herein, we report a smartphone-based three-channel ratiometric fluorescence device for simultaneous determination of Hg2+, Fe3+ and Cu2+ in environmental samples on site. It was based on the fluorescence quench mechanism of Hg2+, Fe3+ and Cu2+ to three kinds of doped carbon quantum dots, which were prepared by pyrolysis methods using ammonium citrate, citric acid + 1,10-phenanthroline, and EDTA + thiourea as initial materials, respectively. By using a multivariate calibration method, the mutual interference among Hg2+, Fe3+ and Cu2+ can be corrected. Under the optimized conditions, the limits of detection for Hg2+, Cu2+ and Fe3+ are 3, 0.5, and 30 nM, respectively. The proposed device offers the advantage of portability, sensitivity and reliability for field analysis.
关键词： Smartphone,Heavy ions,Portable device,Carbon quantum dots,Ratiometric fluorescence,Triple-channel
更新于2025-09-11 14:15:04
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Electrochemiluminescent immunoassay for neuron specific enolase by using amino-modified reduced graphene oxide loaded with N-doped carbon quantum dots
摘要： An ultrasensitive electrochemiluminescence based sandwich immunoassay is presented for determination of neuron specific enolase. The method uses silver-cysteine nanowires as the capture probe and a composite made of amino-modified reduced graphene oxide and nitrogen-doped carbon quantum dots as the signal probe. It was synthesized by covalent coupling of amino-modified reduced graphene oxide to the carboxy groups of nitrogen-doped carbon quantum dots. The nanowires possess a large specific surface and abundant functional groups which facilitate immobilizing the primary antibody (Ab1). The amino-modified reduced graphene oxide is employed as a carrier for loading a large number of the quantum dots and secondary antibody (Ab2). This increases the electrochemiluminescence intensity of quantum dots. Response to neuron specific enolase is linear in the 0.55 fg·mL?1 to 5.5 ng·mL?1 concentration range. It has a detection limit of 0.18 fg·mL?1 (at S/N = 3). The relative standard deviation (for n = 6) is less than 2.9%. The assay is highly sensitive, reproducible, selective and stable.
关键词： Silver-cysteine nanowires,Sensor,Neuron specific enolase,Carbon quantum dots,Graphene oxide
更新于2025-09-11 14:15:04
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Red‐Carbon‐Quantum‐Dot‐Doped SnO <sub/>2</sub> Composite with Enhanced Electron Mobility for Efficient and Stable Perovskite Solar Cells
摘要： An efficient electron transport layer (ETL) plays a key role in promoting carrier separation and electron extraction in planar perovskite solar cells (PSCs). An effective composite ETL is fabricated using carboxylic-acid- and hydroxyl-rich red-carbon quantum dots (RCQs) to dope low-temperature solution-processed SnO2, which dramatically increases its electron mobility by ≈20 times from 9.32 × 10?4 to 1.73 × 10?2 cm2 V?1 s?1. The mobility achieved is one of the highest reported electron mobilities for modified SnO2. Fabricated planar PSCs based on this novel SnO2 ETL demonstrate an outstanding improvement in efficiency from 19.15% for PSCs without RCQs up to 22.77% and have enhanced long-term stability against humidity, preserving over 95% of the initial efficiency after 1000 h under 40–60% humidity at 25 °C. These significant achievements are solely attributed to the excellent electron mobility of the novel ETL, which is also proven to help the passivation of traps/defects at the ETL/perovskite interface and to promote the formation of highly crystallized perovskite, with an enhanced phase purity and uniformity over a large area. These results demonstrate that inexpensive RCQs are simple but excellent additives for producing efficient ETLs in stable high-performance PSCs as well as other perovskite-based optoelectronics.
关键词： electron transport layers,SnO2,planar perovskite solar cells,synchrotron-based GIXRD,red-carbon quantum dots
更新于2025-09-11 14:15:04
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Fluorescence ON-OFF switching, Boolean logic gates like behavior of carbon quantum dots and highly sensitive bovine serum albumin sensing
摘要： We demonstrate ?uorescence “ON-OFF” switching and photonic logic gates based on ?uorescence response of carbon quantum dots (CQDs) in the presence of graphene oxide (GO), reduced graphene oxide (RGO), and bovine serum albumin (BSA). We study the excited state electron and energy transfer interactions among the carbon based materials in detail through steady state ?uorescence (SSF) and time resolved ?uorescence (TRF) spectroscopy. CQDs function as donor; GO and RGO function as acceptors. SSF results show the ?uorescence “turn-OFF” behavior of CQDs in the presence of GO and RGO, and the reason is explained through Stern-Volmer plots. TRF results reveal a decrease in the decay time components of CQDs in the presence of GO and RGO. The gradual recovery of quenched ?uorescence of CQDs is observed by the addition of BSA at nanomolar concentrations which shows the highly sensitive “turn-ON” BSA sensing. Single input and two inputs photonic logic gates are implemented based on the ?uorescence response of CQDs in the presence of GO, RGO, and BSA in di?erent input combinations. The NOT, PASS1, NOR, and IMPLICATION gates like behavior of CQDs is demonstrated.
关键词： bovine serum albumin sensing,fluorescence ON-OFF switching,carbon quantum dots,Boolean logic gates
更新于2025-09-11 14:15:04
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Carbon quantum dots derived by direct carbonization of carbonaceous microcrystals in mesophase pitch
摘要： Aggregation of the central aromatic ring system of asphaltene molecules due to π–π interaction can lead to the formation of carbon quantum dots (CQDs). However, to date, such a roadmap has not been demonstrated. Here, we present a simple approach to the synthesis of CQDs by direct carbonization of dispersed carbonaceous microcrystals in mesophase pitch. The size of the as-prepared CQDs is modulated by adjusting the nucleation temperature for mesophase formation. Due to the oxygen-free character, the CQDs exhibit excitation-independent fluorescent behavior with a quantum yield up to 87%. The CQDs were successfully applied to fluorescent detection of Fe3+ ions with good specificity and sensitivity. Our results not only provide a scalable production of CQDs at low cost, but also give valuable clues to understand the solidification of asphaltene at nanoscale.
关键词： Fe3+ ions,carbonization,mesophase pitch,fluorescent detection,carbon quantum dots
更新于2025-09-11 14:15:04
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One-step hydrothermal synthesis of silver-doped carbon quantum dots for highly selective detection of uric acid
摘要： In this paper, a simple and convenient fluorescence method for detection of uric acid (UA) based on Ag-doped carbon quantum dots (Ag-CQDs) is developed. The Ag-CQDs contain Ag species could bond with UA, which promoted the electron and/or energy transfer and produced high quenching extent. Thus, the fluorescence intensity of Ag-CQDs decreased in the presence of UA. Under the optimal condition, the UA sensor exhibited a linear response in the range of 0.005-100 μM with a detection limit of 0.35 nM (S/N=3). Ag-CQDs demonstrated high sensitivity and rapid response to UA over a wide range of concentration indicating their great potential as a fluorescent probe for chemical sensing. Moreover, this method has successfully applied to detect UA in human urine samples.
关键词： silver,doping,carbon quantum dots,uric acid,fluorescence
更新于2025-09-11 14:15:04
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Enhancing Nonradiative Energy Transfer between Nitridized Carbon Quantum Dots and Monolayer WS2
摘要： Two-dimensional (2D) monolayer (1L) transition metal dichalcogenides (TMDs) suffer from a low absorption in the visible light region. Nonradiative energy transfer (NRET) is an effective method to enhance such absorption, which, as shown in this study, can be accomplished by using surface nitridized carbon quantum dots (CQDs). The optical absorption and photoluminescence (PL) of CQDs in the visible light region can be greatly enhanced by increasing the level of nitridization. The nitridized CQDs exhibit weak p-type doping but strong PL quenching in contact with vapor transport (VT)-deposited 1L-WS2. Owing to the good overlap between the fluorescence and absorption spectra for CQDs and 1L-WS2, an interactive NRET process reduces the PL lifetimes of both CQDs and 1L-WS2. The NRET efficiency can be greatly enhanced by up to 73% for samples coated with CQDs of increasing surface nitridization.
关键词： Nonradiative energy transfer,Nitridized carbon quantum dots,Optical absorption,Monolayer WS2,Photoluminescence
更新于2025-09-11 14:15:04
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Highly Selective and Sensitive Sensing of Toxic Mercury Ions Utilizing Carbon Quantum Dot-Modified Glassy Carbon Electrode
摘要： In this paper, a novel synthesis of 1 nm sized metal-free carbon quantum dots (CQDs) and their electrochemical application vis-à-vis mercury (Hg) sensing have been demonstrated. The characterization of synthesized CQDs was done by FT-IR, HR-TEM, XRD and UV–Vis analysis. Furthermore, the CQD-modified electrode shows an excellent sensing ability toward deleterious Hg ion even when 600-fold of excess of interfering ions such as Cu2+, Pb2+, Cd2+, Na+, K+, Mg2+, Ba2+, Bi2+, Fe2+, Zn2+ and Hg2+ are present. A wide linearity range (0.5–300 nM) and the lowest limit of detection (2.5 nM) are exhibited by the proposed sensor with potential scanning from ? 0.7 to + 0.7 V vs Ag/AgCl at a scan rate of 20 mV. In addition, the CQD-modified electrode displays an outstanding recovery results toward Hg in various real water samples. This study promotes new possibilities of designing various electrochemical sensors based on CQD nanocomposite.
关键词： Differential pulse voltammetry,Mercury,Cyclic voltammetry,Carbon quantum dots,Electrochemical Sensing
更新于2025-09-11 14:15:04
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Paper sensor of curcumin by fluorescence resonance energy transfer on nitrogen-doped carbon quantum dot
摘要： Paper Sensor detection methods are attractive in wide analytical applications. Presented herein is a paper sensor and ?uorescence methods that was ?rstly developed to detect curcumin (Cur) based on ?uorescence resonance energy transfer (FRET) between nitrogen-doped carbon quantum dots (NCQDs) and Cur. The facile ?uorescent method was demonstrated to detect Cur in the range of 0e2600 mM with a detection limit of 0.13 mM. And facile paper sensor of Cur was fabricated and displayed at concentration of 0 mM, 100 mM, 200 mM, 300 mM, 400 mM, 500 mM and 600 mM, respectively. In additions, it was realized for determination of Cur in real samples including orange juice and curry solution. Compared with the reported methods, the present method is simple, rapid and sensitive for detecting Cur.
关键词： Nitrogen-doped carbon quantum dots (NCQDs),Curcumin (Cur),Fluorescence resonance energy transfer (FRET),Paper-based sensor
更新于2025-09-11 14:15:04
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Bioinspired Synthesis of Carbon Dots/g-C <sub/>3</sub> N <sub/>4</sub> Nanocomposites for Photocatalytic Application
摘要： This study reports a fast and green preparative strategy to synthesize water soluble and fluorescent carbon quantum dots (CQDs) through hydrothermal method by using low cost organic waste of human fingernails as the carbon precursor for the first time. The coupling of CQD with pure carbon nitride (g-C3N4) was further explored to enhance the latter’s performance in photocatalysis of 2,4-dicholorophenol (2,4-DCP), a toxic and recalcitrant compound mostly released from industrial effluent. Such coupling overcame the weakness of pure g-C3N4 in photocatalysis process by broadening its visible light absorption and promoting the charge separation. As a result, the removal rate of CQD/ g-C3N4(10) was up to 71.53%, which was approximately 1.5 times higher than that of pure g-C3N4 under sunlight irradiation. The morphological structure, optical properties and chemical compositions of CQDs/g-C3N4 composites were characterized using various spectroscopic techniques including field emission scanning electron microscopy (FESEM), Energy Dispersive X-Ray (EDX) and Ultraviolet-visible diffuse reflectance spectra (UV-DRS).
关键词： Photocatalysis,Hydrothermal method,Carbon quantum dots,4-dichlorophenol,2,g-C3N4
更新于2025-09-10 09:29:36