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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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Orange‐Emissive Carbon Quantum Dots: Toward Application in Wound pH Monitoring Based on Colorimetric and Fluorescent Changing
摘要： Monitoring of wound pH is critical for interpreting wound status, because early identification of wound infection or nonhealing wounds is conducive to administration of therapies at the right time. Here, novel orange-emissive carbon quantum dots (O-CDs) are synthesized via microwave-assisted heating of 1,2,4-triaminobenzene and urea aqueous solution. The as-prepared O-CDs exhibit distinctive colorimetric response to pH changing, and also display pH-sensitive fluorescence. Benefiting from the response of O-CDs over a wound-relevant pH range (5–9), medical cotton cloth is selected to immobilize O-CDs through hydrogen bond interactions, the resultant O-CDs-coated cloth with emission at 560 nm shows a high response to pH variation in the range of 5–9 via both fluorescence and visible colorimetric changes. Moreover, the sensitivity of fluorescence to pH is capable of establishing an analytical mode for determining pH value. Further, the O-CDs-based pH indicator possesses not only superior biocompatibility and drug compatibility but also excellent resistance leachability and high reversibility. Importantly, the usage of O-CDs-coated cloth to detect pH is free from the interference of blood contamination and long-term storage, thus providing a valuable strategy for wound pH monitoring through visual response and quantitative determination.
关键词： fluorescent bandages,wound pH monitoring,carbon quantum dots,colorimetric response,dual-mode
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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Ultrasensitive Fe3+ Ion Detection Based on Carbon Quantum Dot-Functionalized Solution-Gated Graphene Transistors
摘要： An ultrasensitive real-time Fe3+ ion sensor based on carbon quantum dot (CQD)-functionalized solution-gated graphene transistors (SGGTs) is designed. Special functional groups are designed to modify the surface of CQDs, which allows the device to have ultra-high sensitivity and excellent selectivity. More importantly, the components of the sensor except the gate electrode can be repeatedly used.
关键词： carbon quantum dots,ultrasensitive sensor,solution-gated graphene transistors,Fe3+ ion detection
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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A novel carbon quantum dots (CQDs) modified Cs <sub/>4</sub> PW <sub/>11</sub> O <sub/>39</sub> Fe(III)(H <sub/>2</sub> O) material to achieve high photocatalytic property
摘要： Keggin-type polyoxometalates is a kind of promising photocatalyst with adjustable light absorption range. However, the high recombination rate of photogenerated charge carriers hampered its photocatalytic efficiency. To solve this weakness, novel carbon quantum dots (CQDs) modified Cs4PW11O39Fe(Ⅲ)(H2O) photocatalysts (CQDs/Cs4PW11Fe) have been synthesized via a hydrothermal process. Phase structure, morphology, optical and electronic properties of the as prepared photocatalysts were systematically characterized by XRD, SEM, TEM, DRS and surface photovoltage tests. It could be found that CQDs was well deposited on the surface of Cs4PW11Fe, which has broadened the light absorption of Cs4PW11Fe. The photodegradation efficiencies of the CQDs/Cs4PW11Fe composite photocatalysts for RhB under visible light irradiation were clearly enhanced. Trapping experiments were carried out to detect the photocatalytic mechanisms. The charge transfer and separation efficiencies of the samples were confirmed by electrochemical impedance spectroscopy tests.
关键词： Carbon quantum dots,Organic pollutants,Photocatalysis,Solar energy utilization,Cs4PW11O39Fe(Ⅲ)(H2O)
更新于2025-09-19 17:13:59
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New Immunosensing-Fluorescence Detection of Tumor Marker Cytokeratin-19 Fragment (CYFRA 21-1) Via Carbon Quantum Dots/Zinc Oxide Nanocomposite
摘要： The rapid detection of lung cancer in early stages using the antigen cytokeratin-19 fragment (CYFRA 21-1) as a tumor marker in human serum plays an important role in the survival of patients and taking a fast surgical reaction. This study aimed to employ the green synthesized carbon quantum dots conjugated zinc oxide nanocomposite as a highly sensitive fluorescence immunosensing solution for fast determination of CYFRA 21-1 antigen in human serum. The suggested method was conducted by applying a hydrothermal method to prepare carbon quantum dots using Citrus lemon pericarp. The formed carbon quantum dots were used in the reduction and stabilization of zinc acetate to synthesize carbon quantum dots-zinc oxide nanocomposite. To form a sandwich capping antibody-antigen-antibody immunosensing system, a CYFRA 21-1 antigen was trapped by immobilizing a non-conjugated monoclonal antibody BM 19.21 on the surface of carbon quantum dots-zinc oxide nanocomposite and another monoclonal antibody KS 19.1, which was coated on the microtiter well surface. This system has a tunable fluorescence feature recorded at excitation and emission of λex = 470 and λem = 520 nm, respectively. The suggested nanocomposite fluorescence immunosensing system displayed a linear relationship of 0.01–100 ng mL?1 with a limit of detection of 0.008 ng mL?1. The suggested immunosensing system based on carbon quantum dots-zinc oxide nanocomposite provides a promising approach for rapid diagnoses of lung cancer by detecting CYFRA 21-1 in human serum.
关键词： Carbon quantum dots,Fluorescence,Immunoassay,Cytokeratin fragment 21-1 antigen,Zinc oxide nanoparticles
更新于2025-09-19 17:13:59
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FRET study between Carbon Quantum Dots and Malachite Green by Steady State and Time Resolved Fluorescence Spectroscopy
摘要： Background: Understanding the interaction between different organic dyes and carbon quantum dots helps us to understand several photo physical processes like electron transfer, energy transfer, molecular sensing, drug delivery and dye degradation processes etc. Objective: The primary objective of this study is to whether the carbon quantum dots can act as an electron donor and can participate in the different photo physical processes. Methods: In this work, carbon quantum dots (CQDLs) are synthesized in most economical and simple carbonization method where petals of Nelumbo nucifera L. are used as a carbon precursor. The synthesized CQDLs were characterized by using experimental techniques like UV?Vis absorption, FT-IR, transmission electron microscopy (TEM), steady-state and time-resolved fluorescence spectroscopy. Results: The spectral analysis shows that the so synthesized CQDLs are spherical in shape and its diameter is around 4.2 nm. It shows the fluorescence emission maximum at 495 nm with a quantum yield of 4%. In this work the interaction between carbon quantum dots (CQDLs) and an organic dye malachite green (MG) is studied using fluorescence spectroscopic technique under ambient pH condition (At pH 7). The quenching mechanism of CQDLs with MG was investigated using Stern-Volmer equation and time-resolved fluorescence lifetime studies. The results show that the dominant process of fluorescence quenching is attributed to Forster Resonance Energy Transfer (FRET) having a donor acceptor distance of 53 ? where CQDLs act as a donor and MG acts as an acceptor. Conclusion: This work has a consequence that CQDLs can be used as a donor species for different photo physical processes such as photovoltaic cell, Dye sensitized solar cell, and also for antioxidant activity study.
关键词： Carbon quantum dots,stern-volmer plot,Nelumbo nucifera L.,FRET,malachite green
更新于2025-09-19 17:13:59
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Waste to wealth translation of e-waste to plasmonic nanostructures for surface-enhanced Raman scattering
摘要： Here we report, for the first time, a simple one-step recycling of discharged batteries, a major constituent of electronic waste (e-waste), into value-added fluorescent nanomaterials-carbon quantum dots (CQDs). The e-waste derived CQDs (eW-CQDs) were systematically characterized for their optical properties, including absorption, photoluminescence, quantum yield, and emission lifetime. The morphology of these nanomaterials was determined by high-resolution transmission electron microscopy, selected area electron diffraction, and X-ray diffraction, whereas Raman spectroscopy was used to confirm their carbonaceous architecture. To broaden the range of applications, the eW-CQDs were employed in the synthesis of plasmonic nanostructures (eW-Au@CQDs) via a one-step chemical reduction strategy. Both eW-CQDs and eW-Au@CQDs were further tested for their suitability to be used as surface-enhanced Raman (SERS) substrates for the detection of methylene blue (MB), a model dye and Raman reporter. Our results show that while eW-CQDs are not ideal for SERS applications, eW-Au@CQDs, when deposited on a gold-modified screen-printed carbon electrode (SPE), produce strong MB SERS signals. With further optimization, these eW-Au@CQDs-modified SPEs could find applications in SERS-based sensing. This study demonstrates a new, promising, and sustainable approach of converting e-waste such as discharged batteries into value-added products with potential for a wide range of applications.
关键词： E-waste,Discharged batteries,Recycling,SERS,Carbon quantum dots,Methylene blue
更新于2025-09-19 17:13:59
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Photocatalytic activation of peroxymonosulfate by surface-tailored carbon quantum dots
摘要： In this study, carbon quantum dots (CQDs) were synthesized by a low-cost and scalable approach and the oxygen functional groups were fine-tuned by chemical post-treatment. It was found that the CQDs could be applied as visible-light-responsive photocatalysts for activation of peroxymonosulfate (PMS) and remediation of aqueous organic dyes. Phenylhydrazine modified CQDs (CQDs-PH) presented high efficiency for degradation of methylene blue due to selective removal of carboxylic groups and inhibited recombination of photogenerated electron-hole pairs. The effects of catalyst dosage, species and concentrations of dyes, and initial pH values on the photodegradation efficiency were systematically investigated and the alkaline condition facilitates the separation of photoinduced charge carriers and promotes the dye decoloration. The reactive oxygen species produced in the photocatalysis were identified by radical quenching tests and the mechanism was elucidated. Superoxide radicals were generated from PMS activation via electron transfer from CQDs and played the primary role for organic oxidation. In addition, photogenerated holes on the valence band of CQDs also participated in the dye decomposition.
关键词： peroxymonosulfate,superoxide radicals,Photocatalysis,oxygen groups,carbon quantum dots (CQDs)
更新于2025-09-19 17:13:59