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Determination of chondroitin sulfate in synovial fluid and drug by ratiometric fluorescence strategy based on carbon dots quenched FAM-labeled ssDNA
摘要： Chondroitin sulfate (CS) plays an increasingly important role in clinical settings and pharmacy quality control. However, sensitive and simple methods for CS detection remain limited. In this work, positively charged nitrogen doped carbon dots (P-NCDs) with internal luminescence and quenching property to FAM-labeled random-sequence ssDNA (F-ssDNA) were prepared by a simple heating method. P-NCDs attached and quenched F-ssDNA through electrostatic interaction to form the system of P-NCDs and F-ssDNA (P-NCDs/F-ssDNA) with retained fluorescence intensity of P-NCDs. The highly negatively charged CS reacted electrostatically with P-NCDs and then replaced F-ssDNA in P-NCDs/F-ssDNA to recover the fluorescence intensity of the original quenched F-ssDNA while retaining the internal fluorescence intensity of P-NCDs. Thus, by using restored F-ssDNA as the signal controlled by adding CS to P-NCDs/F-ssDNA, a ratiometric fluorescence strategy based on the retained fluorescence of P-NCDs as reference signal was fabricated through synchronous fluorescence spectrometry for the sensitive detection of CS. Under the optimal experimental conditions, a linear equation for CS was obtained for CS concentration within the range of 0.05–2.0 μg/mL. The method was also successfully applied for the accurate determination of CS in joint fluid samples of arthritic patients, chondroitin sulfate tablets, and chondroitin sulfate eye drops, suggesting its appreciable application potential in the clinic.
关键词： Positively charged nitrogen doped carbon dots (P-NCDs),Chondroitin sulfate,Synchronous fluorescence spectrometry,Ratiometric fluorescence strategy,Synovial fluid
更新于2025-09-23 15:19:57
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Understanding the Citric Acid-Urea Co-Directed Microwave Assisted Synthesis and Ferric Ion Modulation of Fluorescent Nitrogen Doped Carbon Dots: A Turn On Assay for Ascorbic Acid
摘要： Herein, nitrogen doped carbon dots (NCDs) were synthesised from citric acid and urea via a previously reported microwave assisted route. The NCDs shows emission maximum at 500 nm on excitation at 400 nm. The fluorescence of NCDs decreases slightly with increase in basicity of solution up to pH 7.5 and then increases again after pH 8.5, along with a blue-shift in tested alkaline pH. This pH dependent blue-shift indicates the presence of both carboxyl?carboxylate and phenol?phenolate prototropic equilibrium in NCDs. Due to the special interaction of these phenolates and carboxylates on NCDs surface with di- or tri- valent heavy transition metal ions; it is demonstrated that ferric ion (Fe3 + ion) can quench the fluorescence of NCDs. This Fe3 + induced static quenching of NCDs is a collaborative effect of inner filter effect, aggregation and ferromagnetism. However, Ascorbic acid (AA) can recover the fluorescence of Fe3 + quenched NCD with detection limit as low as 96 μM. This detection strategy has good selectivity towards AA over other antioxidants, saccharides, proteins and neurotransmitters. Furthermore, (spiked) human serum and (spiked) human urine were analysed and found good recovery percentage.
关键词： Fluorescence,Ascorbic Acid,Biosensor,Inner Filter Effect,Iron(III),Carbon Dots
更新于2025-09-19 17:15:36
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Highly selective fluorescence chemosensor based on carbon-dot-aerogel for detection of aniline gas
摘要： Solid-state fluorescence sensing has become a research hotspot because it is simple and convenient in practical operation. In this study, the carbon dots (CDs)-silica aerogel solid fluorescent material was developed for the selective detection of aniline gas. The blue CDs were prepared by one-step simply hydrothermally treating low-cost sawdust, then CDs-silica aerogel composite material with the high specific surface areas and high porosity was prepared by sol-gel method based on abundant hydroxyl groups on the surface of the CDs which can initiate the gelation of tetraethyl orthosilicate. It is capable of selectively distinguishing toxic gaseous aniline with other volatile organic vapors by sensitive fluorescence quenching, and under optimal conditions, the fluorescence quenching efficiency of aniline gas can reach 76.4%. It is expected that our strategy might provide a new approach for developing a low cost, fast and sensitive CDs-based probe for environmental sensing applications.
关键词： Silica aerogel,Fluorescence chemosensor,Aniline gas,Carbon dots
更新于2025-09-19 17:15:36
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Blue, green, and red full-color ultralong afterglow in nitrogen-doped carbon dots
摘要： Carbon dots (CDs) with tunable emission colors and multiple emission modes are highly desirable in advanced optical anti-counterfeiting. Some pioneering efforts to trigger additional long-lived emission modes, nevertheless, did not perfectly solve the issue of printability and color-tunability in practical applications. Herein, we developed an encapsulating-dissolving-recrystallization route for the synthesis of CD-based anti-counterfeiting inks, and accordingly realized blue, green, and red full-color afterglow emissions from these CD-based inks when printed on paper. The printed inks simultaneously possessed triple emission modes including fluorescence (FL), delayed fluorescence (DF), and room-temperature phosphorescence (RTP), among which the long-lived emissions (DF and RTP) could be selectively activated by using different excitation wavelengths. We believe that the proposed synthetic route in this work may promote the development of multicolor-encoded and multiple-mode-integrated optical anti-counterfeiting systems, and will expand the application of CD-based materials to the fields of sensing, photodynamic therapy and bio-imaging.
关键词： afterglow,anti-counterfeiting,carbon dots,full-color,multiple emission modes
更新于2025-09-19 17:15:36
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Rare earth-free composites of carbon dots/metal-organic framework as white light-emitting phosphor
摘要： Over the last few years, numerous efforts have been made to develop white light-emitting metal-organic frameworks (MOFs), due to the useful features of MOFs such as ultrahigh surface areas and tunable pore architecture. However, rare earth (RE) ions are most commonly applied as phosphors in these materials so far, raising device cost and environmental concerns. Here, we designed a new type of RE-free material capable of white light-emission upon excitation at 365 nm, with the photoluminescence quantum yield in solid state reaching 37%, fabricated by compositing carbon dots (CDs) with Zr(IV)-based MOF. WLEDs constructed by depositing the CDs/Zr-MOF nanocomposite on a commercial UV LED chip feature a CIE chromaticity coordinate at (0.31, 0.34), high color rendering index (CRI) of 82, and luminous efficiency of 1.7 lm/W.
关键词： carbon dots,rare-earth-free luminophores,white-light-emission,Zr-MOFs,down-conversion LEDs
更新于2025-09-19 17:15:36
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Amphipathic carbon dots with solvent-dependent optical properties and sensing application
摘要： Carbon dots (CDs) have been regarded as novel heavy-metal-free fluorescent materials because of their prominent optical features. In this work, one type of amphipathic CDs is prepared by facile one-step solvothermal treatment of p-Phenylenediamine. The obtained CDs own numerous surface function groups which endow them prominent dispersibility in different solvents. Absorption, steady-state and time-resolved spectroscopy have been adopted to investigate the mutual influence between the surface groups and different solvent molecules on the optical properties of the CDs. Strong solvatochromic behavior with tunable emission from blue to green and strict excitation-independent emission characteristic can be observed when the as-prepared CDs are dissolved in different solvents, suggesting their feasible sensing applications as an alternative of solvatochromic dye molecules. Furthermore, highly selective detection of Cu2+ ions using the as-synthesized CDs as sensing probes is achieved. It is expected that the investigated CDs with solvent-dependent optical properties as well as selective Cu2+ detection may have broad application prospects in bioimaging and biodetecting.
关键词： Cu2+ detection,Optical properties,Solvent-dependent,Carbon dots
更新于2025-09-19 17:15:36
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On-off-on fluorescent carbon dots from waste tea: Their properties, antioxidant and selective detection of CrO42?, Fe3+, ascorbic acid and L-cysteine in real samples
摘要： In this work, we reported an economical plant-based hydrothermal method for one-pot green synthesis of water-soluble carbon dots (Tea-CDs) by using waste tea extract as a carbon source. The synthesized Tea-CDs were characterized by UV-visible, fluorescence, FT-IR, TEM, XPS and XRD. The Tea-CDs were found to remove hydroxyl and superoxide anion radical in vitro. In addition, the Tea-CDs exhibited bright blue fluorescence under UV-light (λex=365 nm), and the fluorescence could be effectively quenched by CrO4 2- and Fe3+ ions. Meanwhile, the fluorescence of Tea-CDs-CrO4 2- and Tea-CDs-Fe3+ systems could be again easily recovered by ascorbic acid (AA) and L-cysteine (L-Cys). As an on-off-on fluorescent nano-sensor of the Tea-CDs, the sensitive detection of CrO4 2-, Fe3+, AA and L-Cys were all performed, showing that the good linear relationships between fluorescence intensity of Tea-CDs and concentration of all testing samples. Finally, the sensors successfully detected CrO4 2-, Fe3+, AA and L-Cys in commercially available real samples with satisfactory recovery ranges. The prepared sensors offer distinct advantages including low cost, simple handling, good sensitivity and high selectivity.
关键词： carbon dots,waste tea,L-cysteine,ascorbic acid,on-off-on fluorescent nano-sensor,metal ions
更新于2025-09-19 17:15:36
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Identification of Bacteria by a Fluorescence Sensor Array based on Three Kinds of Receptors Functionalized Carbon Dots
摘要： The identification of bacteria is a crucial issue in the field of medical diagnosis, environmental monitoring and food safety. Conventional methods need long culturing times, highly skilled operators, or recognition elements specific to each kind of the bacteria. Alternatively, sensor arrays offer a cost-effective and simple approach using multiple cross-reactive receptors. Here, a facilely constructed fluorescence sensing array was developed for the identification of various bacteria. The sensor array consists of three facile synthesized carbon dots functionalized with different receptors (boronic acid, polymixin and vancomycin), which could bind to all the bacteria with different affinity instead of a specific one. A unique molecular fingerprint of each kind of bacteria was obtain from the fluorescence response pattern generated from three kinds of carbon dots. By using linear discrimination analysis (LDA) of the response pattern, the effective discrimination of six bacteria studied was demonstrated. The proposed sensor array approach may pave the way for the development of simple, rapid and effective identification of multiplex bioactive samples.
关键词： bacterial identification,cross-reactive receptors,carbon dots,pattern recognition,sensor array
更新于2025-09-19 17:15:36
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Ratiometric fluorometric determination of silver(I) by using blue-emitting silicon- and nitrogen-doped carbon quantum dots and red-emitting N-acetyl-L-cysteine-capped CdTe quantum dots
摘要： A ratiometric fluorometric assay for silver(I) is described. The method makes use of a dually emitting quantum dot hybrid, which is composed of (a) blue-fluorescent silicon- and nitrogen-doped carbon quantum dots (CQDs), and (b) of red-emitting CdTe quantum dots (QDs) capped with N-acetyl-L-cysteine. The red-emitting CdTe QDs undergo strong and specific quenching by Ag(I), whereas the blue-emitting N,Si-CQDs are not quenched. The two kinds of QDs are mixed and used as a ratiometric fluorescent probe. A linear relationship is found between the log of intensities [(I608/I441)0/(I608/I441)] and the concentration of Ag(I) in the range from 5.0–1000 nM, and the limit of detection (at S/N = 3) is 1.7 nM. Possible interferents (including 17 general metal ions, 12 anions and fulvic acid) do not interfere with the determination. The assay was successfully used for the determination of Ag(I) in surface water and wastewater samples. The fluorescence quenching mechanism of the ratiometric assay system was also discussed in detailed.
关键词： Fluorescence quenching mechanism,Surface water,Nitrogen-doped carbon dots,Silver ions,Silicon-doped carbon dots,Wastewaters,3-Aminopropyltriethoxysilane functionalized carbon dots,Quenching efficiency,Dual-emission quantum dots hybrid,Fluorescent probe
更新于2025-09-19 17:13:59
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Carbon Allotrope-Based Optical Fibers for Environmental and Biological Sensing: A Review
摘要： Recently, carbon allotropes have received tremendous research interest and paved a new avenue for optical fiber sensing technology. Carbon allotropes exhibit unique sensing properties such as large surface to volume ratios, biocompatibility, and they can serve as molecule enrichers. Meanwhile, optical fibers possess a high degree of surface modification versatility that enables the incorporation of carbon allotropes as the functional coating for a wide range of detection tasks. Moreover, the combination of carbon allotropes and optical fibers also yields high sensitivity and specificity to monitor target molecules in the vicinity of the nanocoating surface. In this review, the development of carbon allotropes-based optical fiber sensors is studied. The first section provides an overview of four different types of carbon allotropes, including carbon nanotubes, carbon dots, graphene, and nanodiamonds. The second section discusses the synthesis approaches used to prepare these carbon allotropes, followed by some deposition techniques to functionalize the surface of the optical fiber, and the associated sensing mechanisms. Numerous applications that have benefitted from carbon allotrope-based optical fiber sensors such as temperature, strain, volatile organic compounds and biosensing applications are reviewed and summarized. Finally, a concluding section highlighting the technological deficiencies, challenges, and suggestions to overcome them is presented.
关键词： carbon nanotubes,graphene,sensors,nanomaterials,carbon dots,optical fiber,nanodiamonds,nanocoating
更新于2025-09-19 17:13:59