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Determination of cholic acid in body fluids by β?cyclodextrin-modified N-doped carbon dot fluorescent probes
摘要： An easy, dependable, and sensitive cholic acid activity experiment was designed based on β?cyclodextrin-modi?ed carbon dot (β?CD-CD) nanoprobes with speci?c host–guest recognizing ability and photoelectron transfer capability. The β?CD-CD nanoprobes were characterized by infrared, ultraviolet-visible, and ?uorescence spectroscopy and transmission electron microscopy. The ?uorescence of the probes under optimized conditions linearly responded to cholic acid concentration from 0 to 650 μmol·L?1 with a detection limit of 25 nmol·L?1. The probes also performed well in detecting cholic acid in serum and urine samples with an average recovery rate of 97.1%–103.4%. Thus, this study provides a reliable, rapid, and easy method of cholic acid detection in body ?uids that can be potentially applied in medical studies.
关键词： Host–guest recognition,β?cyclodextrin,Cholic acid,Photoinduced electron transfer,Carbon dots
更新于2025-11-14 17:03:37
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Sensitive surface-enhanced Raman scattering detection of atrazine based on aggregation of silver nanoparticles modified carbon dots
摘要： The development of precise detection methods with simply operation for pesticides in various environmental samples is a particular challenge. Here a highly sensitive surface-enhanced Raman scattering (SERS) approach for the selective detection of trace atrazine was proposed with R6G as a Raman reporter, which was adsorbed on silver nanoparticles modified carbon dots. The latter were prepared by the reduction of Ag+ by carbon dots. In the presence of atrazine, the aggregation of the modified carbon dots due to the interaction between silver nanoparticles and atrazine led to great enhancement of the SERS signal of R6G. Under optimal assay conditions, the limit of quantification was estimated to be 10 nM, which matched with the standard for drinking water quality of China and WHO defined limit. A good linear response to atrazine was found in the concentration range of 10-1000 nM with the relative standard deviations between 1.8% and 5.6%. The determination of atrazine in real water samples was also carried out to confirm the practicability of the proposed method, which showed the recoveries from 95% to 117.5%. The target induced aggregation for enhancing the signal offered great potential for sensitive on-site detection of atrazine in environments.
关键词： Silver nanoparticles,Pesticides,SERS detection,Target induced aggregation,Atrazine,Carbon dots
更新于2025-11-14 17:03:37
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A comparative study on photocatalytic hydrogen evolution activity of synthesis methods of CDs/ZnIn2S4 photocatalysts
摘要： The introduction of carbon materials in photocatalytic systems can significantly enhance the photocatalytic hydrogen evolution activity. Here, we proposed and fabricated carbon nanodots/ZnIn2S4 (CDs/ZIS) samples via three methods. The morphology, chemical elements and valence, and photoelectric properties of CDs/ZIS samples were systematically characterized by SEM, TEM, XPS, UV and PL. The photocatalytic H2 production experiments indicate that the photocatalytic performance of all CDs/ZIS samples has been significantly improved, which could be attributed to the fact that serving as an excellent electron acceptor, CDs can accelerate the separation efficiency of photogenerated electrons and holes. The samples prepared via one-pot hydrothermal method exhibit the optimal photocatalytic activity and the corresponding H2 production rate of 4.15 mmol g?1 h?1 under visible light irradiation (λ > 420 nm), which is about 2.92 times higher than pure ZIS. Our work presented the influence of synthetic method on photoelectric performance and photocatalytic activity of CDs/ZIS nanocomposites, and provided a reliable idea for improving the photocatalytic performance of photocatalyst toward practical applications.
关键词： Synthesis methods,ZnIn2S4,Photocatalytic hydrogen evolution,Carbon dots
更新于2025-11-14 15:29:11
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Rapid preparation of homogeneous carbon dots with yellow fluorescence and formation mechanistic investigation
摘要： In this study, homogeneous carbon dots with yellow fluorescence and high absolute fluorescence quantum yields (78.6%) were firstly prepared through a one-step solvothermal method without complicated process of separation, in which sodium citrate, carbamide, and anhydrous calcium chloride were adopted as precursors, while toluene was selected as solvent. The as-prepared carbon dots with an average size of 5.9 nm have a high degree of crystallinity. According to the discussion of the formation mechanism carbon dots, it is found that the toluene guarantee the formation of crystalline core and Ca2+ promotes the formation of carbonaceous core with high crystallinity, which is responsible for the ultrahigh quantum yield. Furthermore, the fluorescent properties of carbon dots are excellent in organic solvents and could be quenched by water, making them a promising material used without any modification in the detection of water in organic solvents, which has a great influence on organic chemical reaction, and may even determine the resultant, yield, and selectivity of organic reaction.
关键词： Detection of water content,Ultrahigh quantum yield,Yellow fluorescence,Carbon dots,Quantum dot
更新于2025-11-14 15:28:36
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Facile synthesis of yellow emissive carbon dots with high quantum yield and their application in construction of fluorescence-labeled shape memory nanocomposite
摘要： Synthesizing carbon dots (CDs) with efficient long-wavelength emissions (i.e., yellow- to red light) generally suffer from sophisticated approaches, time-consuming process, harsh conditions, and requirement of organic solvent; also, a further limitation of the resulting CDs is relatively low quantum yield (QY) in aqueous solution. Herein, novel yellow emitting CDs (Y-CDs) with a considerable QY of 62.8% were synthesized from a precursor comprising resorcinol and o-phenylenediamine via a facile microwave method. To probe the fluorescence mechanism, another typical resorcinol-derived CDs using ethylenediamine as dopant were fabricated as well, showing strong green emission with an absolute QY of 60.6%. Spectroscopic and structural characterizations indicated that the distinct redshift of green to yellow emission depended on the dimension of conjugated sp2-domain and the content of graphitic N heavily, while the excellent QY was highly related to the low proportion of defective sp2 carbon cluster and high nitrogen content within CDs. Moreover, the Y-CDs were confirmed to be capable of introducing additional crosslinking points in poly(vinyl alcohol) (PVA) polymer, which resulted in the Y-CDs-contained nanocomposite behaving superior and tunable water-induced shape recovery performances. Importantly, since being labeled with long-wavelength emission, the responsiveness of PVA/Y-CDs composite will contribute to its versatile utilization in biology-relevant fields.
关键词： shape recovery,fluorescence mechanism,yellow emission,carbon dots,nanocomposite
更新于2025-11-14 15:23:50
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Full color carbon dots through surface engineering for constructing white light-emitting diodes
摘要： White light-emitting diodes (WLEDs) devices are replacing the filament lamp and they can provide a light close to the natural sunlight, which have thus drawn considerable attention in these recent years. It remains a scientific challenge to develop WLEDs using environmentally friendly, easy-to-process and cost-effective phosphors. Here we synthesized blue-, green- and red-carbon dots (denoted as B-, G- and R-CDs) by a facile solvothermal method with high dispersity both in aqueous and organic solvent. The quantum yield (QY) of the R-CDs achieved up to 24.7%. These CDs can be easily dissolved in polyvinylpyrrolidone (PVP) colloid, leading to the production of ultraviolet (UV)-excited LED devices to avoid the retinal damage caused by blue ray excitation. The fluorescence emission of the WLED has a wide band, covering the whole visible light region. Importantly, the influence of doping that gives rise to the change of emissive colors has been elucidated by X-ray photoelectron spectroscopy (XPS) combined with a computation method in order to provide a systematic controllable tuning on the functionalization of CDs. As such, WLEDs were demonstrated with color coordinates of (0.33, 0.33), a color temperature of 5612 K in the CIE chromaticity diagram with good anti-photobleaching and a color rendering index (CRI) of 89.
关键词： polyvinylpyrrolidone,White light-emitting diodes,solvothermal method,UV-excited LED devices,density functional theory,quantum yield,X-ray photoelectron spectroscopy,carbon dots
更新于2025-11-14 15:18:02
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Non-enzymatic sensing of dopamine by localized surface plasmon resonance using carbon dots-functionalized gold nanoparticles
摘要： A highly selective, sensitive, and rapid colorimetric sensor for the determination of dopamine (DA) was developed using the color change of S-doped carbon dots functionalized gold nanoparticles (S-CDs@Au NPs). The base of the method is the formation of a complex between the amine groups of dopamine with carboxylic groups of S-CDs@Au NPs followed by their aggregation with Fe3+ ions which acts as the linkers causing a red shift from 520 to 670 nm in the localized surface plasmon peak of S-CDs@Au NPs. The ratio of absorbance intensity at 670 nm to 520 nm was monitored as the analytical signal for determination of dopamine. The parameters affecting the analytical signal including reaction time, solution pH, the concentration of Au NPs and concentration of Fe3+ were optimized. At optimized conditions, the calibration curve was linear in the concentration range of 0.81-16.80 μM of dopamine. The detection and quantification limits were 0.23 μM and 0.77 μM, respectively. The intra-day and inter-day relative standard deviation (RSDs) at 5.0 μM of DA were 3.9% and 5.6%, respectively (n = 5). The applicability of the method for determination of DA in dopamine ampoule, urine and serum human samples was investigated.
关键词： Carbon dots,Localized surface plasmon resonance,Colorimetric chemical sensor,Dopamine,Gold nanoparticles
更新于2025-11-14 15:18:02
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Study on heterogeneous photocatalytic ozonation degradation of ciprofloxacin by TiO2/carbon dots: Kinetic, mechanism and pathway investigation
摘要： In this study, the objective was mainly focusing on the mechanism investigation of ciprofloxacin (CIP) degradation by photocatalytic ozonation process which carried out by ozone and TiO2 with a low content of carbon-dots (CDs) under simulated sunlight irradiation. The physicochemical properties of the prepared photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) X-ray photoelectron spectroscopy (XPS) and zeta potential. Comprehensive investigation has proven the process to be efficient in the removal of CIP with high yield of reactive species (?OH, O2 ?—, h+, etc.). Kinetic model on pH investigation found out a repulsive force between the photocatalysts and CIP intensified with the increasing pH, so did the production rate of hydroxyl radicals (?OH), while eventually reached a balance and achieved a maximum degradation rate. The results indicated that the enhancement mechanism was triggered by the photoexcited electron accumulated on CDs and transferred by ozone, resulting in the continuous generation of h+, O3 ? — and O2 ? —. Possible photocatalytic ozonation degradation pathways of CIP were proposed according to the identifications of intermediates using high-resolution accurate-mass spectrometry (HRAM) LC-MS/MS.
关键词： ciprofloxacin,reactive species,carbon-dots,photocatalytic ozonation,transformation pathway
更新于2025-11-14 15:15:56
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In Situ Synthesis of Fluorescent Mesoporous Silica–Carbon Dot Nanohybrids Featuring Folate Receptor-Overexpressing Cancer Cell Targeting and Drug Delivery
摘要： Multifunctional nanocarrier-based theranostics is supposed to overcome some key problems in cancer treatment. In this work, a novel method for the preparation of a fluorescent mesoporous silica–carbon dot nanohybrid was developed. Carbon dots (CDs), from folic acid as the raw material, were prepared in situ and anchored on the surface of amino-modified mesoporous silica nanoparticles (MSNs–NH2) via a microwave-assisted solvothermal reaction. The as-prepared nanohybrid (designated MSNs–CDs) not only exhibited strong and stable yellow emission but also preserved the unique features of MSNs (e.g., mesoporous structure, large specific surface area, and good biocompatibility), demonstrating a potential capability for fluorescence imaging-guided drug delivery. More interestingly, the MSNs–CDs nanohybrid was able to selectively target folate receptor-overexpressing cancer cells (e.g., HeLa), indicating that folic acid still retained its function even after undergoing the solvothermal reaction. Benefited by these excellent properties, the fluorescent MSNs–CDs nanohybrid can be employed as a fluorescence-guided nanocarrier for the targeted delivery of anticancer drugs (e.g., doxorubicin), thereby enhancing chemotherapeutic efficacy and reducing side effects. Our studies may provide a facile strategy for the fabrication of multifunctional MSN-based theranostic platforms, which is beneficial in the diagnosis and therapy of cancers in future.
关键词： Targeted drug delivery,Fluorescence imaging,Mesoporous silica nanoparticles,Carbon dots,Chemotherapy
更新于2025-11-14 14:48:53
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One pot green synthesis of C-dots from groundnuts and its application as Cr(VI) sensor and in vitro bioimaging agent
摘要： The emergence of ?uorescent carbon dots (C-dots) has received special attention due to their distinct characteristics which are advantageous for optical sensing and bioimaging applications. Cr(VI) is considered a hazardous environmental pollutant hence requires a simple and e?ective method for its detection and recovery. Herein, we have synthesized both C-dots and N-doped C-dots from ground nuts employing a cost-e?ective and green hydrothermal method. N-C-dots exhibits a remarkably enhanced quantum yield (17.6%) as compared to undoped C-dots (7.8%). In addition,the N-C-dots showed amazing selectivity towards Cr(VI) in the metal sensing application. Cr (VI) induced quenching of ?uorescence was recovered using Humic acid as well as Glutathione thus exhibiting an o?-on type sensing mechanism. The limit of detection (LOD) for Cr(VI) using N-C-dots was found to be 0.1 mg/L. C-dots possess comparatively low cytotoxicity than N-C-dots at higher concentration thereby making them an e?cient candidate for bioimaging of MCF-7 cells.
关键词： Bioimaging,Carbon dots(C-dots),Cr(VI) sensing,Groundnut,Glutathione,Humic acid
更新于2025-09-23 15:23:52